Dissertations / Theses on the topic 'CD84'

TESI:

L'objecte d'estudi d'aquesta tesi és el receptor CD84, que pertany a la Família del CD150, alhora englobada dins la superfamília de les immunoglobulines. La família del CD150 està composta per nou receptors que comparteixen una elevada homologia estructural, i que poden presentar interacció homotípica o heterotípica. Sis dels membres d'aquesta família presenten a la seva cua citoplasmàtica almenys un motiu d'unió a les proteïnes adaptadores SAP i EAT-2. La deficiència del gen que codifica per la proteïna SAP (SH2D1A), és la causant de l'aparició d'una immunodeficiència lligada al cromosoma X, la Síndrome XLP, corresponent a un desordre de baixa incidència, que es caracteritza per una elevada susceptibilitat al virus del Epstein-Barr. El CD84 es troba àmpliament expressat a la superfície dels leucòcits i és l'únic membre de la família que es troba expressat a nivells elevats en mastòcits en estat basal. Els mastòcits són les principals cèl·lules efectores de les reaccions al·lèrgiques, tot i que es troben implicats en molts altres processos, inclosos la immunitat innata i l'autoimmunitat. La via clàssica d'activació dels mastòcits s'inicia amb la unió de la IgE al receptor d'alta afinitat per la IgE (FcepsilonRI) i dóna lloc a l'alliberació d'histamina i molts altres mediadors. Les respostes mastocitàries requereixen una regulació molt precisa que està mitjançada per un ampli ventall de factors i molècules. L'objectiu d'estudi d'aquesta tesi ha estat determinar la funció del receptor CD84 en l'activació mastocitària, donada l'elevada expressió d'aquest immunoreceptor en mastòcits, i les implicacions d'aquest tipus cel·lular en la regulació de les respostes del sistema immunitari.
Mitjançant estudis de sobre-expressió del receptor CD84 en una línia mastocitària de rata, RBL-2H3, vam caracteritzar el CD84 com un nou receptor inhibidor de la cascada de senyalització iniciada pel receptor d'alta afinitat per la IgE. Vam demostrar que el receptor CD84 inhibeix tant esdeveniments primerencs (com la senyalització de calci, la reorganització del citoesquelet, la desgranulació i la fosforilació de MAPKs), com esdeveniments tardans (síntesi de citocines), mitjançant la interacció homotípica, on el receptor actua com el seu propi lligand. Mitjançant la generació de mutants puntuals per a les quatre tirosines que el receptor CD84 presenta a la seva cua citoplasmàtica, vam disseccionar la implicació de cadascuna d'elles en el mecanisme inhibitori del CD84, i vam comprovar que les tirosines responsables de la inhibició del CD84 són les que es troben a les posicions 279 i 324. Per altra banda, les tirosines 262 i 299, que es troben englobades en motius d'unió a les proteïnes adaptadores SAP i EAT-2, no participen en el mecanisme inhibitori del CD84, determinant que la funció negativa del receptor és independent de SAP. Mitjançant estudis bioquímics, vam determinar que les molècules adaptadores c-CBL i DOK-1 participen en el mecanisme inhibitori del CD84. Vam fer també estudis de transfecció en cèl·lules COS, amb la finalitat d'establir les cinases implicades en la fosforilació del receptor CD84 i vam determinar LYN i FPS/FES com les cinases principals en la fosforilació de les tirosines 279 i 324, respectivament. Finalment, vam utilitzar una línia mastocitària humana, LAD-2, que ens ha permès corroborar els efectes observats amb la línia RBL-2H3 en un sistema fisiològicament més proper a l'humà. Vam comprovar que l'efecte inhibitori del CD84, es manté en els esdeveniments primerencs estudiats en LAD-2, i vam confirmar també, en aquesta línia cel·lular, la implicació de DOK-1 en la senyalització negativa del CD84. Les dades obtingudes en aquesta tesi perfilen el receptor CD84 com un molècula important en la funció dels mastòcits i una possible diana terapèutica en al·lèrgies inflamatòries.
CD84 belongs to the CD150 family of receptors. This family is a subset of the CD2 cell-surface receptor Ig superfamily and it is defined by its binding to the cytoplasmic adaptors SAP and EAT-2. SAP/SH2D1A is the product of the gene mutation in X-linked lymphoproliferative disease (XLP), a rare immune disorder commonly triggered by Epstein-Barr virus. CD84 is a homophilic adhesion molecule expressed in a broad range of leukocytes. The CD84 is the only member of the CD150 family expressed in resting mast cells. Mast cells are currently recognized as effector cells in many settings other than mere allergic reactions, including innate immunity and autoimmunity. The classic and most studied activation pathway of these cells starts with the binding of IgE to the high-affinity Fc receptor for IgE (FcepsilonRI); and the release of histamine and other mediators after crosslinking of surface-bound IgE by allergen. Appropriate activation and fine tuning of mast cell responses is mediated by a complex array of factors and molecules. The aim of this work was to determine the function of CD84 in mast cells.
The CD84 receptor was transfected and overexpressed in the rat mast cell line RBL-2H3. We found that this receptor has an inhibitory effect in early events (degranulation, cytoskeleton arrangement, calcium influx, MAPKs phosphorylation and PI3K phosphorylation) and late events (cytokines synthesis). Generation of mutants for each of the four tyrosines present in the cytoplasmic tail of the CD84, demonstrates that this inhibitory effect is related with Y279 and Y324. Interestingly, Y262 and Y299, which are part of a consensus motif for SAP or EAT-2 binding, do not participate in CD84-mediated inhibition. Thus, we postulate that the inhibitory effect of the CD84 is not mediated by SAP or EAT-2 in mast cells. We performed transfection studies with COS cells and we determined that LYN and FPS/FES kinases are the main kinases in Y279 and Y324 phosphorylation, respectively. Finally we used a human mast cell line, LAD-2, to corroborate the effects observed in RBL-2H3. We found that CD84 receptor has also an inhibitory effect in IgE-dependent early events in LAD-2, whereas no inhibitory effect was seen using non-immunological stimuli. These data suggest that CD84 may play a role in modulating FcepsilonRI-mediated signaling in mast cells and it could have a protective role against undesired allergic and inflammatory responses.

Les malalties autoimmunes es caracteritzen per una pèrdua de la tolerància als antígens propis que dóna lloc a l'aparició de limfòcits autoreactius. La susceptibilitat genètica és un factor determinant en el desenvolupament de l'autoimmunitat i és el resultat de l’acció combinada de diversos gens. S'han identificat diferents locus de susceptibilitat i polimorfismes dels gens que contribueixen al desenvolupament de l'autoimmunitat sistèmica. Entre d'altres, s’ha trobat un locus principal de susceptibilitat al lupus eritematós sistèmic (LES) en ratolins (Sle1b) i humans (1q23) localitzat en el cromosoma 1 (Wang et al) que conté els gens de la família SLAM (Signaling Lymphocyte Activation Molecule), un grup de receptors de membrana amb importants funcions immunoreguladores. Els membres de la família SLAM han estat identificats, en els últims anys, com un grup de receptors que modulen l'activació i la diferenciació d'una àmplia gamma de tipus cel·lulars involucrats en la resposta immune innata i adaptativa. La família SLAM està constituïda per nou molècules de membrana pertanyents a la superfamília de les immunoglobulines (IgSF): SLAMF1, SLAMF2 (CD48), SLAMF3 (CD229 o LY9)), SLAMF4 (CD244 o 2B4), SLAMF5 (CD84), SLAMF6 (CD352 o NTB-a), SLAMF7 (CD319 o Cracco), SLAMF8 (CD353 o BLAME) i SLAMF9, que s'expressen diferencialment en les cèl·lules del sistema hematopoètic. La regió extracel·lular d'aquests receptors conté típicament un domini immunoglobulina (Ig) variable (IgV) en l'extrem N-terminal i un domini Ig constant (IgC2) a l'extrem C-terminal, excepte SLAMF3 (CD229), que està format per dos sèries de IgV / IgC2. A través d'aquests dominis estableixen interaccions específiques amb els seus lligands, la majoria dels casos de tipus homofílic, excepte la proteïna CD48 que és el receptor de CD224. Els lligands de SLAMF8 i 9 no s'han descrit fins ara. Sis dels receptors SLAM contenen un o més motius ITSM (Immunoreceptors Tyrosine-based switch motif) en la seva cua citoplasmàtica, que serveixen com a llocs d'unió per a molècules adaptadores i enzims amb dominis SH2 (Src homology 2 domains). Les molècules adaptadores SAP (SLAM-associated protein), EAT-2 (EWS / FLI activated transcript-2) i ERT (EAT-2 related Transducer) tenen una gran afinitat per aquest motiu. Estudis amb ratolins mostren l'expressió diferencial de dues isoformes de Ly108 (SLAMF6), que difereixen en la seva regió citoplasmàtica, entre ratolins normals i ratolins susceptibles al lupus. L'expressió de la isoforma Ly108-1, amb dos dominis ITSM, es troba incrementada respecte a l'altra isoforma Ly108-2, amb tres motius ITSM, a les cèl·lules B i T de ratolins susceptibles al lupus en comparació amb ratolins normals. Darrers estudis d'aquesta proteïna demostren l'existència d'una nova isoforma (Ly108-H1), absent en ratolins susceptibles al lupus i que protegeix d'aquesta malaltia als ratolins transgènics. Recentment, s’ha descrit una expressió alterada de dos receptors SLAM, CD244 i CD319, i una expressió diferencial d'isoformes d'aquestes molècules en pacients amb LES. Per tant, un concepte emergent derivat d'aquest i d'altres estudis, és que l'expressió diferencial d'isoformes dels receptors SLAM pot contribuir a la susceptibilitat a trencar l’autotolerància. Un dels membres d'aquesta família és la proteïna CD84, la qual ha estat caracteritzada i estudiada àmpliament en el nostre grup durant els últims anys. Es tracta d'una proteïna d'uns 50-80 kDa depenent del seu grau de glicosilació, amb un ectodomini format per un domini IgV en el seu extrem N-terminal al que li falta el pont disulfur; i un domini IgC2 en el seu extrem C-terminal amb dos ponts disulfur. La seva cua citoplasmàtica conté dos dominis ITSM mitjançant els quals s'uneix al domini SH2 de diferents molècules adaptadores, entre elles SAP. La interacció homofílica té lloc a través del domini IgV. RESULTATS 1. CD84 té almenys quatre ARN missatgers diferents La base de dades ECgene descriu set isoformes de la proteïna CD84. Només en quatre d'aquestes isoformes s'han localitzat seqüències d’ARN missatger i d'ESTs (Expressed Sequence Tag), que juntament amb una estructura proteica compatible, farien possible que aquestes isoformes expressessin a nivell de proteïna. Els estudis in silico realitzats van demostrar que el transcrit H1C22218.5, amb dues seqüències d'ARNm i 91 ESTs correspondria al gen íntegre o full length (CD84_FL); amb una regió codificant de 1017 pb formada per vuit exons. El transcrit H1C22218.2, amb una seqüència d'ARNm i 66 ESTs té una regió codificant de 642 pb a la qual li falten els exons 2 i 5 (CD84_Delta2, 5). En canvi el transcrit H1C22218.3, amb 5 seqüències d'ARNm i 93 ESTs està format per 984 pb i li falta l'exó 5 (CD84_Delta5). Finalment, el transcrit H1C22218.4, amb una seqüència d'ARNm i 88 ESTs està format per 816 pb i li falten els exons 5 i 6 (CD84_Delta5, 6). Estudis previs del grup van demostrar que CD84 s'expressa a nivell de proteïna en diverses línies cel·lulars del sistema immune. Per aquesta raó, i amb la intenció d'esbrinar si les isoformes descrites en les bases de dades eren presents en aquestes línies cel·lulars, es van dur a terme diferents PCR amb oligonucleòtids específics per CD84 dissenyats a les unions dels exons per aconseguir una major especificitat. La primera PCR correspon a una amplificació de la cua citoplasmàtica i dóna lloc a tres bandes de 341 pb, 308 pb i 210 pb. La seqüenciació de les bandes obtingudes demostrar que la banda de 341 pb corresponia a la proteïna íntegra (CD84_FL), mentre que la banda de 308 pb corresponia a una cua citoplasmàtica amb un exó menys, que coincidia amb les seqüències dels transcrits CD84_ Delta2, 5 i CD84_Delta5. Finalment, la banda de 272 pb amplificar una seqüència coincident amb CD84_Delta5, 6. Una segona PCR amb els oligonucleòtids dissenyats a la unió dels exons 1-3, unió present únicament en la possible isoforma CD84_ Delta2,5, va permetre diferenciar entre aquest transcrit i el CD84_Delta5. La seqüenciació de la banda obtinguda va confirmar que es corresponia amb el transcrit CD84_ Delta2,5. L'amplificació de la cua citoplasmàtica en les diferents línies cel·lulars va demostrar que almenys tres de les quatre isoformes esmentades s'expressen en diferents línies cel·lulars com cèl·lules B (Ramos, Namalwa, Raji, Daudi i Cess), cèl·lules T (Jurkat, Hsb2 i Molt4), cèl·lules mieloides (Hl60, U937, K562 i THP-1) i NK (Yt i Nkl). Les isoformes esmentades també es troben expressades en cèl·lules de sang perifèrica de voluntaris sans, en melsa i en amígdala amb una expressió de CD84_Delta5, 6 molt marcada a melsa. La PCR específica per al transcrit CD84_Delta2, 5 demostrar que aquest es troba lleugerament expressat en algunes cèl·lules T i B, però no en NK, PBMC, melsa i amígdala. 2. La isoforma CD84_Delta2, 5 no s'expressa en la membrana Diversos assajos per FACS en cèl·lules · cèl·lules COS-7 transfectades transitòriament amb la construcció pCDNA3.1 CD84_Delta2, 5 i amb l’anticòs a-CD84 2151, el qual reconeix el segon domini immunoglobulina de la proteïna, no van permetre identificar la isoforma. El marcatge intracel·lular per comprovar la presència de la isoforma al citoplasma, també va ser negatiu. Es va decidir doncs utilitzar una construcció de la isoforma que contingués el tag fluorescent GFP, per estudiar la localització de la proteïna. Es van transfectar transitòriament cèl·lules COS-7 i es va observar el resultat en el microscopi de fluorescència, indicant que la proteïna no es troba localitzada a la membrana. A causa de que el nostre interès per aquesta isoforma es centra en el possible paper funcional que podria tenir en faltar-li el domini responsable de l'adhesió, es va decidir seguir amb els assajos funcionals sense estudiar aquesta isoforma. 3. L'anticòs 688.1 contra la cua citoplasmàtica de CD84_Delta5, 6 reconeix específicament aquesta isoforma Aprofitant que la isoforma CD84_Delta5, 6 té en la seqüència de nucleòtids de la seva cua citoplasmàtica un canvi en la pauta de lectura que genera una seqüència d'aminoàcids única, es va generar un anticòs que reconegués específicament aquesta cua. La validació de l'anticòs demostrar que aquest no reconeix la resta d'isoformes de CD84 en transfectants transitoris de cèl·lules COS-7 per FACS, però sí que reconeix la isoforma d'interès. També es va demostrar que l'anticòs 688.1 immunoprecipita específicament la isoforma CD84_Delta5, 6 a transfectants transitoris de cèl·lules COS-7. La immunofluorescència en cèl·lules adherents transfectades transitòriament també mostra l’especificitat d'aquest anticòs enfront de la proteïna íntegra. 4. La isoforma CD84_Delta5, 6 s'expressa diferencialment en les línies cel·lulars testades Un cop identificades les isoformes i analitzada la seva expressió a nivell gènic, l'anticòs generat permetre analitzar l'expressió de l’isoforma CD84_Delta5, 6 a nivell de proteïna. Els estudis per FACS demostren que aquesta està present en totes les línies cel·lulars testades, i els nivells d'expressió es correlacionen amb els resultats obtinguts a nivell gènic, indicant que l'anticòs és sensible a l'expressió diferencial en cadascuna de les línies. D'aquesta manera, mentre que la proteïna CD84 total s'expressa de manera important en les línies de cèl·lules B, els nivells de isoforma CD84_Delta5,6 són baixos en aquest tipus cel·lular. En canvi, en línies de cèl·lules T, on generalment CD84 es troba expressada en un nivell més baix, la isoforma CD84_Delta5, 6 té una expressió relativa més elevada. Els nivells més alts d'expressió de la isoforma es troben en les línies de llinatge mieloide, on l'expressió de CD84 total també és alta. En el cas de les línies de cèl·lules NK gairebé la totalitat del CD84 trobat correspon a la isoforma. 5. La isoforma CD84 Delta5, 6 es detecta en les diferents subpoblacions de PBMC estudiades L'anàlisi per citometria de flux en les diferents subpoblacions de PBMC va permetre conèixer l'expressió diferencial de CD84_Delta5, 6 en individus sans. La subpoblació B1 de cèl·lules B (IgM + CD19 + CD5 +), la qual està involucrada en la immunitat humoral, té una expressió de la isoforma més elevada que la resta de cèl·lules B (IgM + CD19 + CD5-). En les cèl·lules T CD4 +, les cèl·lules memòria expressen més la proteïna total que les cèl·lules verges (CD3 + CD4 + CD45ROlow), mentre que la isoforma s'expressa de manera similar en ambdues poblacions. Pel que fa a les cèl·lules · cèl·lules T reguladores (CD4 + CD25 + FoxP3 +), tant el nivell de CD84 total com el de la isoforma és significatiu. En les cèl·lules T CD8 +, l'expressió de CD84 és considerablement més important en cèl·lules efectores memòria (CD8 + CD45RA-CCR7-) que en cèl·lules centrals memòria (CD8 + CD45RA-CCR7 +), com també ho és l'expressió de la isoforma. En canvi, les cèl·lules naïve (CD8 + CD45RA + CCR7 +), tot i tenir una expressió de CD84 total similar a les cèl·lules efectores (CD8 + CD45RA + CCR7-), tenen una expressió de CD84_Delta5, 6 més elevada que aquesta. En cèl·lules NK (CD3-CD16 + CD56 +), l'expressió de la isoforma és elevada en relació a l'expressió de CD84 total. Els monòcits tenen una expressió significativa tant de CD84 com de CD84_Delta5, 6. 6. La isoforma CD84 Delta5, 6 s'internalitza deficientment respecte la proteïna CD84 Estudis d'activació de cèl·lules Jurkat transfectades amb els ADNc de les diferents isoformes van demostrar que la isoforma CD84_Delta5, 6 té una expressió més alta després de l'activació que la resta d’isoformes. Això va fer pensar que probablement el fet de no tenir la cua citoplasmàtica amb les quatre tirosines, donaria lloc a un reciclatge deficient de la proteïna i en conseqüència, d'una acumulació en la membrana. Per demostrar si això era cert, es van fer diversos estudis d'internalització amb diferents procediments de citometria, com l’ús de l'aparell Amnis, que combina la citometria de flux amb la microscòpia de fluorescència i permet veure la localització de la proteïna marcada en una cèl·lula. El resultat obtingut va demostrar que les cèl·lules Jurkat transfectades amb la isoforma CD84_Delta5, 6 tenen una internalització més baixa que les transfectades amb CD84_FL, en condicions normals, el que incrementa amb l'activació. 7. Estudi de l'expressió de CD84 i de la isoforma CD84_Delta5, 6 a malalties autoimmunes Deu pacients de LES i dotze d'AR van participar en l'estudi de l’expressió de CD84 i de la isoforma CD84_Delta5, 6 a les diferents subpoblacions de PBMC analitzades en l'apartat 5. Els resultats obtinguts van ser comparats amb els valors d'expressió dels mateixos paràmetres de dotze voluntaris sans. D'altra banda, es comparar l'expressió de CD84 amb un altre membre de la família SLAM, NTBA, el qual ha estat assenyalat com una proteïna implicada en algunes malalties autoimmunes. En termes generals, es va veure un augment de l'expressió de CD84_Delta5, 6 a totes les subpoblacions estudiades de malalts de LES, resultat que coincideix en un estat d'activació en els estudis in vitro. En AR en canvi, els resultats assenyalen una tendència contrària en algunes subpoblacions. CONCLUSIONS Les isoformes de CD84 d'estudi han estat identificades per PCR en les línies cel·lulars d'interès. S'ha vist que aquestes isoformes es troben expressades de forma diferencial tant en les línies cel·lulars com en cultius primaris. Inicialment la isoforma CD84_Delta2, 5 ens va semblar interessant perquè en faltar el primer domini immunoglobulina, a través del qual té lloc la interacció homofílica, donaria lloc a importants deficiències en la interacció amb altres cèl·lules. Però els resultats observats mostren que la isoforma no transloca a la membrana, el que pot ser degut al fet que part del pèptid líder forma part del segon exó, absent en aquesta isoforma. La manca d'aquest fragment de pèptid líder podria fer que la proteïna no tingués la capacitat de translocar a la membrana. La isoforma CD84_Delta5, 6 té una deficient internalització causa probablement a la manca dels motius tirosina de la seva cua citoplasmàtica. La generació dels anticossos específics per a la isoforma CD84_Delta5, 6 ens va permetre estudiar l'expressió d'aquesta isoforma tant en línies cel·lulars com en les diferents subpoblacions de sang perifèrica. S'ha vist una expressió diferencial en les diferents subpoblacions estudiades, la qual cosa pot estar indicant un paper funcional important d'aquesta isoforma. Una possible explicació que es desprèn dels resultats amb pacients de LES i AR podria ser que la presència de més CD84_Delta5, 6 a la membrana fa que, encara que la proteïna no sigui funcionalment activa a nivell de senyalització intracel·lular, produeixi més adhesió i per tant afavoreixi la senyalització d'altres molècules coestimuladores, donant lloc a una hiperactivació del sistema immune. La conclusió final que es pot extreure d'aquest treball és que hi ha indicis que demostren que CD84 i els seus isoformes podrien tenir un paper important en la ruptura de la tolerància i el desenvolupament de la autoimmunitat. Les dues malalties estudiades, LES i AR, han donat resultats oposats. D'una banda, sembla ser que en el LES ha lloc una activació cel·lular. L'expressió més elevada de la isoforma en cèl·lules naïve podria indicar que CD84 és un factor de susceptibilitat al desenvolupament d'aquesta malaltia. D'altra banda, en AR no s'observa diferència d'expressió en els malalts sense tractament, mentre que el grup tractat presenta un increment de la proporció entre la proteïna total i la isoforma, suggerint que CD84 podria ser un biomarcador en el tractament de l’artritis.
The membrane protein CD84 belongs to SLAM family, in the immunoglobulins superfamily. It was established as a molecule CD (cluster of differentiation) in 1995 in the 6th International Workshop on Human Leukocyte Differentiation Antigens (HLDA). In recent years, the SLAM family members have been identified as a group receptors that modulate the activation and differentiation of various cell types involved in the innate and adaptive immune response. In addition, many studies indicate that the genetic region where SLAM family genes are located is a susceptibility locus for Systemic lupus erythematosus (SLE). In the last years, it has been demonstrated some evidences that shows a clear implication of polymorphisms and alternative splicing isoforms generated by different members SLAM family in the development of certain autoimmune diseases, especially in SLE. Following this way, an emerging concept is that the differential expression of isoforms of SLAM receptors may contribute to susceptibility to break self-tolerance. Moreover, studies in our group showed that CD84 is a costimulatory protein widely expressed in the hematopoietic system, both human and mouse. It is in this context that we characterized different isoforms of CD84 and its study possible involvement in the development of autoimmunity.

La família del CD150 es troba constituïda per nou proteïnes expressades en la superficie dels leucòcits implicades en l'activació dels limfòcits i que pertanyen a la superfamília de les immunoglobulines. Els receptors CD84, CD150 (SLAM), CD229 (Ly9), CD244 (2B4), NTB-A i CS1 s'associen amb els adaptadors SAP (SLAM-associated protein) i EAT-2. L'adaptador SAP és una proteïna intracel·lular que es troba mutada en malalts amb el síndrome d'immunodeficiència lligat al cromosoma X (XLP).

Aquest estudi s'ha analizat l'expressió de CD84, CD150, CD229 i CD244 en diferents leucòcits i poblacions limfocitàries mitjançant citometria de fluxe. El CD84 i el CD150 estaven presents en timòcits, cèl·lules T madures i cèl·lules presentadores d'antígen. L'expressió de CD84 i CD150 era elevada en cél·lules T memòria. L'expressió de CD150 s'incrementava molt després de l'activació. Al contrari que el CD84, el CD150 es trobava absent en monòcits en repòs i en cèl·lules dendrítiques immadures. El CD229 presentava un patró d'expressió restringit a limfòcits. El CD244 s'expressava de forma preferencial en cèl·lules NK, limfòcits CD8+ efectors, monòcits en repòs, basòfils i eosinòfils. Nosaltres hem descrit una distribució de CD84, CD150, CD229 i CD244 més àmplia que la prèviament descrita i hem demostrat que aquestes molècules s'expressen de forma diferencial en les cèl·lules hematopoiètiques. L'expressió heterogènea d'aquests receptors indica que deuen tenir funcions no redundants en la regulació tant del sistema immune adaptatiu com de l'innat.

Amb la finalitat d'identificar el lligand de CD84, es va generar una proteïna de fusió soluble constituïda pels dominis extracel·lulars de CD84 i dos dominis immunoglobulina constants de la IgG humana (CD84-Ig). Degut a que ja havien estat descrites diverses interaccions entre membres de la mateixa família CD2 / CD150, es va assajar la interacció de la proteïna de fusió CD84-Ig amb cèl·lules COS transfectades amb els cDNAs de diferents membres de la família CD2 / CD150. La proteïna de fusió CD84-Ig interaccionava amb cèl·lules transfectades amb el cDNA de CD84, però no s'observava cap interacció amb la resta de membres de la família del CD2 / CD150. Així doncs, el CD84 interaccionava amb ell mateix. Els anticossos contra CD84 que reconeixien el primer domini V-like, bloquejaven la interacció de la proteïna de fusió de CD84 en les cèl·lules transfectades amb el cDNA de CD84 i en plaquetes. A més a més, els resultats obtinguts amb quimeres humà / murí dels dominis extracel·lulars de CD84, demostren que únicament el primer domini extracel·lular N-terminal és el responsable de la interacció homofílica. La interacció CD84-CD84 és independent de la seva cua citoplasmàtica. Finalment, la co-lligació del CD84 amb anticossos contra CD84 o la proteïna de fusió CD84-Ig i anticossos contra CD3, incrementen la secreció de IFN-gamma en limfòcits humans. Així, CD84 interacciona de manera homotípica i actua com a molècula coestimuladora.

Amb l'objectiu d'indentificar el lligand de CD229, es va generar una proteïna de fusió soluble que contenia els dos dominis Ig N-terminals del receptor CD229 (CD229-Ig). La proteïna de fusió CD229-Ig s'unia a les cèl·lules transfectades amb el cDNA de CD229 però no es va detectar cap interacció amb les cèl·lules que expressaven la resta dels membres de la família del CD150, demostrant així que CD229 interaccionava de manera homofílica. Tant el CD229 humà com el de ratolí interaccionen amb ells mateixos. Amb mutants en que es deleccionaven els dominis Ig es va demostrar que el domini immunoglobulina N-terminal mitjançava l'adhesió homofílica. La interacció CD229-CD229 es veia severament compromesa quan es mutaven tres aminoàcids carregats del domini Ig N-terminal: E27 i E29 en el "loop" B-C i R89 en el "loop" F-G, localitzacions predites mitjançant anàlisi computacional. De manera sorprenent, la mutació R44A augmentava la interacció homofílica. Imatges obtingudes per microscopia confocal revelaven que el CD229 es relocalizava en les zones de contacte entre les cèl·lules B i T durant la formació de la sinapsi immunològica. Per tant, CD229 interacciona de forma homotípica i participa en la sinapsi immunològica.

Background: It is well established that adverse experiences during childhood increase the chances of developing emotional psychopathology in adulthood, particularly during vulnerable times, such as pregnancy. Furthermore, research has also demonstrated an association between maternal depression in pregnancy and poorer offspring developmental outcomes. The primary aim of this thesis is to investigate the pathways by which maternal history of abuse during childhood interacts with depression during pregnancy, and how both conditions affect offspring development at six days, eight weeks and one year after birth. The second aim of this study is to explore the alterations in maternal hypothalamic-pituitary-adrenal (HPA) axis functioning during pregnancy among women who are depressed and/or have experienced childhood abuse, and whether these are related to offspring behavioural and physiological regulation as well as to offspring HPA axis response to stress. Methods: The sample comprises 125 pregnant women recruited in the area of South London. Women were assessed in pregnancy for maternal depression and history of abuse in childhood in a one-to-one clinical interviews (25 weeks gestation), and for maternal HPA axis (25 and 32 weeks gestation) through the collection of salivary samples. Infants were administered the Neonatal Behavioural Assessment Scale (NBAS) at six days, with an assessment of the HPA axis functioning before and after the NBAS. Infant HPA axis response was reassessed at eight weeks and one year before and after routine immunization. Results: Women who have been abused in their childhood were 7 times more likely to develop depression in pregnancy than non-abused women. Furthermore, women who were depressed in pregnancy and especially those with both childhood abuse and antenatal depression, showed an increase in the evening cortisol levels at 32 weeks gestation compared with the other women. Neonates of depressed women had poorer behavioural regulation at 6 days, with an increase in their HPA axis stress response following the NBAS compared with neonates of non-depressed mothers, irrespective of maternal history of childhood abuse. At one year, infants of mothers with childhood abuse and depression exhibited greater stress following the immunization compared with infants of non-depressed mothers, but this difference was not seen at 8 weeks. Conclusions: The effects of exposure to childhood abuse and depression in pregnancy can be seen in the mothers’ high level of stress hormone circulating in the evening in the 3rd trimester of pregnancy. Moreover, the effects are also seen in the next generation during the first year of life, as observed in the persistent biological and behavioural changes in the offspring. These findings have implications for clinical practice: doctors and midwives in antenatal clinics should be aware of the importance of asking about women’s own childhood histories and their mental health during pregnancy in order to offer support during their transition to motherhood.

ETS1 est un facteur de transcription (FT) spécifique transposé dans les leucémies aigües. Le rôle essentiel d'ETS1 a été décrit au cours de l'hématopoïèse, plus particulièrement dans la différenciation lymphocytaire T. Son expression temporelle coordonnée participe au contrôle des transitions du stade double négatif (DN) CD4-/CD8- au stade double positif (DP) CD4+/CD8+jusqu'au stade simple positif (SP) CD4+ ou CD8+. Au cours de l'ontogenèse T, ETS1 transactive notamment l'expression des chaînes β et α du récepteur des cellules T (TCR). Nous avons criblé à grande échelle les cibles d'ETS1 aux stades DN et DP en ChIP-Seq, ainsi que desmarques histone et de l'ARN polymérase II (Pol II). Afin de faciliter nos analyses bioinformatiques, nous avons développé deux logiciels, CoCAS et AmaMineReg, qui permettent d'identifier plus facilement les cibles à partir de données brutes et de discriminer les vrais des faux positifs. Nous avons trouvé 5900 cibles en DN et 3400 en DP, principalement intergéniques dont 2000 sont communes, non caractérisées et correspondent aux gènes induits par la réponse immédiate à la signalisation TCR. Parmi les cibles différentiellement exprimées entre les deux stades, ETS1 active les gènes thymus-spécifiques et réprime les gènes hématopoïétiques non T spécifiques,en fonction de la co-occurrence avec le motif RUNX1. Nous avons également caractérisé très clairement le site de fixation en conditions natives, qui se révèle être CTTCCT.De plus, ETS1 co-localise avec des marques chromatines permissives aux régions inter- et intragéniques,caractérisées par un contenu GC, densité de motifs de fixation de FT (SFFT) et conservation inter-espèces accrus
ETS1 is a specific transcription factor (TF) transposed in acute leukemias. key role of ETS1 wasdescribed during hematopoiesis, especially in T lymphocyte differentiation. Its temporal expression participates in the coordinated control of phase transitions from the CD4-/CD8-double negative (DN) stage to CD4+/CD8+ double positive (DP) up to CD4 or CD8 single positivestage (SP). During ontogenesis T ETS1 notably transactivates the expression of the alpha and beta chains of the T-Cell receptor (TCR). We performed genome-wide screening of ETS1 at both DN and DP stages via ChIP-Seq, as well as histone hallmarks and RNA polymerase II (PolII). To facilitate computational analysis we developed two new software suites, and COCASAmaMineReg, which allow easier identification of targets from raw data and to discriminate between true and false positives. We found 5900 targets in 3400 in DN and DP, mostly intergenic, out of which 2000 are common, and correspond to uncharacterized genes induced bythe immediate response to TCR signaling. Among targets differentially expressed between thetwo stages, Ets1 activates thymus-specific genes and represses non T-specific haematopoietic genes depending on the co-occurrence with the RUNX1 motif. We also very clearly characterized the binding site in native conditions, which proved to be CTTCCT. Furthermore, Ets1 colocalizes with permissive chromatin marks in inter-and intra-genic regions, characterized byincreased GC content, TF binding motifs (TFBS) density as well as inter-species conservation

Orientadora : Profa. Dra. Maria Luiza Petzl-Erler
Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Genética. Defesa: Curitiba, 28/02/2012
Bibliografia: fls. 60-63
Resumo: CD80 e CD86, também denominados B7.1 e B7.2, são genes proximamente ligados no cromossomo 3 que codificam glicoproteinas da superfamília das imunoglobulinas, expressas na superfície das células apresentadoras de antígeno. Essas moléculas participam na ativação e inibição das células T através da ligação aos receptores CD28 e CTLA-4. Nesse estudo foram analizados polimorfismos dos genes CD80 e CD86 com o objetivo de investigar a diversidade genética, microevolução e relevância funcional. Foram genotipados 1.124 indivíduos, incluindo brasileiros de ancestralidade predominantemente européia, mista africana e européia e japonesa, 5 populações ameríndias e africanos. As regiões promotoras de CD80 e CD86 foram sequenciadas e utilizadas em ensaios de gene repórter com luciferase em células HEK293T. As proteínas foram quantificadas por citometria de fluxo em monócitos, estimulados com quatro ligantes de TLR, de indivíduos com diferentes genótipos. Sítios de ligação de fatores de transcrição foram inferidos in silico. Todos os alelos analisados foram encontrados em africanos, o que sugere sua origem na África antes das migrações humanas para fora do continente. Cinco novos alelos da região promotora de CD80 foram identificados e confirmados por clonagem e sequenciamento, sendo o promotor 2 o mais provável alelo ancestral. Foi encontrado um efeito de seleção balanceadora em descendentes de japoneses, nos quais todos os alelos apresentam frequências elevadas. O nucleotídeo -79 é monomórfico em 4 populações ameríndias, nas quais a presença do alelo -79G é provavelmente resultado de fluxo gênico. O haplótipo 4 de CD80 apresentou expressão significativamente menor do que os demais devido ao SNP g.-7T>C (rs16829980), g.5C>A (rs41271391) e/ou 287A>T (rs56124423). O SNP g.-7T>C está localizado no sítio de ligação da proteína ativadora AP-1 e de acordo com inferências in silico interfere na ligação. No gene CD86, dois SNPs foram analisados em 2.4 kb incluindo o promotor e a 5'UTR. O SNP CD86 -298T>C não interfere na expressão gênica segundo os experimentos com a luciferase. A quantidade das proteínas em monócitos diferiu significativamente entre os haplótipo de CD80 e os alelos -819T>C (rs11575855) de CD86 e também entre idosos e jovens e entre os quatro diferentes estímulos utilizados. Concluímos que polimorfismos na região 3' do promotor de CD80 alteram significativamente a atividade do promotor. O SNP CD86 -819T>C altera os níveis proteicos de CD86 na membrana de monócitos estimulados. As diferenças encontradas são provavelmente devidas a alterações na capacidade de ligação de fatores de transcrição.
Abstract: CD80 and CD86, also called B7.1 and B7.2, are closely linked genes on chromosome 3 that code for glycoproteins of the immunoglobulin superfamily, expressed on the surface of antigen-presenting cells. These costimulatory molecules play essential roles for stimulation and inhibition of T cells through binding to CD28 and CTLA-4 receptors. In this study, CD80 and CD86 polymorphisms were analyzed to investigate the genetic diversity, microevolution, and the functional relevance of CD80 and CD86 promoter polymorphisms. We genotyped 1,124 individuals, including Brazilians of predominantly European, mixed African and European, and Japanese ancestry, 5 Amerindian populations, and an African sample. The CD80 and CD86 promoter regions were sequenced and functional studies were done using luciferase reporter assays in HEK293T cells, flow cytometry measurements of protein on TLR stimulated monocytes (using four different stimuli) of individuals with different genotypes, and in silico inferences of transcription factor binding. All variants were observed in Africans, which suggests their origin in Africa before the human migrations out of that continent. Five new CD80 promoter alleles were identified and confirmed by cloning and sequencing, and promoter 2 is most likely the ancestral allele. There is evidence of an effect of balancing selection in Japanese-brazilians, where all alleles present high frequencies. Nucleotide-79 is monomorphic in 4 Amerindian populations, where the presence of the -79G allele is probably the result of gene flow from non-Amerindians. CD80 haplotype 4 showed significantly lower promoter activity, caused by SNPs g.-7T>C (rs16829980), g.5C>A (rs41271391) and/or 287A>T (rs56124423). The SNP g.-7T>C is located in the previously reported binding site of activating protein 1 (AP-1) and is predicted to interfere with AP-1 binding. In CD86, two SNPs were analyzed in the 2.4 kb including the promoter and 5'UTR of the gene. Luciferase measurements showed that the CD86 -298T>C SNP did not interfere in gene expression. The protein expression on monocytes differed significantly among CD80 haplotypes and CD86 -819T>C (rs11575855) alleles, and also between age groups and the different stimuli given to the cells. We conclude that polymorphisms within the 3' end of the CD80 promoter significantly affect the activity of the promoter. Further, the CD86 -819T>C SNP has a significant effect on protein levels on the membrane of stimulated monocytes. These differences are most likely caused by differential binding of transcription factors.

Identification of patients with suboptimal nutritional status allows for early treatment intervention. Currently, no definitive test of nutritional status exists. Therefore, this study was conducted to identify possible functional indicators of acute nutritional deprivation. The effects of total nutritional deprivation and subsequent refeeding on lymphocyte functions and subpopulations were examined in 23 healthy cats. Peripheral blood samples were analyzed at various times during fasting and refeeding periods. During the fasting period, decreases were observed in leukocyte number (day 4; p < 0.04), lymphocyte number (p < 0.02), CD4+ cells (day 4; p < 0.06), CD4:CD8 ratio (0 hours; p < 0.004), and mitogen stimulated CD4:CD8 ratio (72 hours; p < 0.15) during the fasting period as compared to baseline. Increases were seen in CD4+ cells (day 7; p < 0.09), CD8+ cells (day 7; p < 0.04) and intracellular calcium (day 4; p < 0.02) as compared to baseline. During the refeeding period increases (p < 0.05) were observed in leukocyte number, CD4+ cells, CD8+ cells, lymphocyte proliferation (p < 0.07) and lymphocyte number (p < 0.004) as compared to day 7. These findings suggest that 7 days starvation had immunosuppressive effects on cats which were alleviated during 7 days refeeding. The use of CD4:CD8 ratio in conjunction with intracellular calcium flux may be useful as indices of nutritional status.
Master of Science

The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
Science, Faculty of
Microbiology and Immunology, Department of
Graduate

Sabemos hoje que os tumores sólidos apresentam uma composição celular heterogênia e que apenas uma pequena parcela dessas células apresenta capacidade de se proliferar e gerar novos tumores. Estudos prévios sobre a formação do câncer de mama têm sido realizados com base na combinação dos marcadores de superfície celular CD44 e CD24. Já foi demonstrado que uma subpopulação de células do câncer de mama com alta expressão de CD44 e baixa expressão de CD24 (CD44+/CD24-) tem maior capacidade de gerar tumores, quando comparadas com a subpopulação de células CD44-/CD24+. O objetivo do estudo foi identificar a taxa de células com fenótipo CD44+/CD24- presentes nos tumores mamários e relaciona-la com a taxa de comprometimento dos linfonodos axilares ipsilaterais por neoplasia, além de avaliar também sua relação com outros fatores sabidamente relacionados com mal prognóstico da paciente. Pacientes e métodos: avaliamos prospectivamente 53 amostras cirúrgicas provenientes de 42 pacientes com diagnóstico histopatológico de carcinoma de mama, quantificando as células CD44+/CD24- por citometria de fluxo. Relacionamos a porcentagem destas células encontrada em cada amostra com o comprometimento axilar, os receptores hormonais e Her-2, a idade da paciente, o grau histológico do tumor, o diâmetro patológico do tumor e o tipo histológico. Resultados: verificamos um significante aumento da população de células CD44+/CD24- no grupo de carcinomas ductais invasivos em pacientes que apresentavam metástase axilar [mediana 8,53% (3,6 71,2%)] em relação ao grupo de pacientes sem linfonodos comprometidos pela neoplasia [mediana 1,49% (0,3 17,1%)] (p=0,0002). Conclusão: concluímos então que quando estudamos vários tumores mamários invasivos de mesma classificação histológica, podemos notar que existe uma variação na quantidade de células CD44+/CD24- entre eles. Nosso estudo mostrou que essa variação está relacionada à agressividade tumoral e à sua capacidade de gerar metástases já que, tumores com maior quantidade de células CD44+/CD24- apresentam maior taxa de comprometimento dos linfonodos axilares.
It is known that solid tumors are composed by a heterogeneous combination of cells and only a small portion of these cells has the capacity to proliferate and generate new tumors. Previous studies about the breast cancer initiation have been based on a combination of CD44 and CD24cell surface markers. It has been shown that this subpopulation of breast cancer cells with high expression of CD44 and low expression of CD24 (CD44+/CD24-) has a greater capacity to generate tumors when compared with the subpopulation of cells CD44- /CD24+. The study objective was to identify whether the rate of cells with CD44+/CD24- phenotype present in breast tumors is related with the rate of ipsilateral lymph node metastasis, in addition to evaluate its relationship with other risk factors known to be related with worst prognosis. Patients and methods: we prospectively evaluated 53 surgical specimens from 42 patients with histological diagnosis of breast cancer, quantifying CD44+/CD24- cells through flow cytometry. We list the percentage of these cells found in each sample with axillary lymph node status, hormone receptors and Her-2, patient age, histological grade, pathological tumor diameter and histological tumorclassification. Results: we find a significant increase of CD44+/CD24- population in the invasive ductal carcinomas, in patients with axillary metastasis [median 8.53% (3.6 - 71.2%)] than in the group of patients without lymph nodes metastasis [median 1.49% (0.3 - 17.1%)] (p = 0.0002). Conclusion: when we studied several invasive breast tumors of same histological classification, we note that there is variation in the number of CD44+/CD24- cells. Our study showed that this variation is related to tumor aggressiveness and their ability to generate metastasis, because tumors with high rate of CD44+/CD24- cells have a higher rate of lymph node metastasis.

Dans une première partie, nous nous sommes concentrés sur l’homéostasie des lymphocytes T CD4+. Nous montrons que le pourcentage de cellules T CD4+CD25+ parmi les cellules T CD4+ est indexé au nombre de cellules IL-2+. Nous avons découvert que la conversion des cellules T CD4+CD25- en cellules T CD4+CD25+ était possible mais inhibé par la présence de cellules T CD4+CD25+. Enfin, dans deuxième partie, nous avons étudié le rôle des lmphocytes T CD4+ dans l’homéostasie des lymphocytes T CD8+. Le co-transfert de cellules T CD4+ naïves accroît la prolifération dûe à la lymphopénie des cellules T CD8+ augmentant de 10 à 20 fois le nombre de cellules T CD8+CD44+CD62Llow récupérées en périphérie sans modifier le nombre de cellules T CD8+CD44+CD62Lhigh. Nous montrons que l’effet auxiliaire est dépendant de l'expression de la molécule CD40 par les cellules non-B de l'hôte et de l’expression de l’IL-2 par les cellules T CD4+ naïves.

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FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas
Leprosy is a chronic infectious disease caused by Mycobacterium leprae that is influenced by host genetic. The poles of the leprosy are occupied by spectrum immunological opposite of the tuberculoid one hand, predominantly of the Th1 immune response and the other by the lepromatous, with predominant Th2 immune response. During the development of immune response, beyond antigen-specific signal is necessary a second signal for activation of T lymphocytes, termed costimulation. This signal can be delivered by costimulatory molecules CD80 and CD86 present on cell surfaces of antigen presented. The binding of these molecules to the receptors CD28 and CTLA-4 T lymphocytes present in the leads to the activation or inhibition of immune response, respectively. The down-regulation of CD80 and CD28 in patients with lepromatous leprosy, and lepromatous borderline can be responsible for defective signaling T cell specific for the antigens of M. leprae through CD80/CD28. This can lead to clonal inactivation of T cells reactive to antigens of M. leprae, and consequently, the bacillus grows without restraint in macrophages. In this work we investigated the possible relationship between this polymorphism in the CD80 and CD86 genes with susceptibility to leprosy and/or clinical forms of the disease. Genotyping of polymorphisms was performed by direct sequencing. CD80 were analyzed six gene SNPs located in the gene promoter region (-454 C/A, -387 T/C, -232 G/A, -79 C/G,-7 T/C and +5 C/A) and Polymorphism insertion/deletion (-557_-561 CATGA) and the CD86 gene was analyzed a SNP in exon 8, position +1057 G/A. For the CD86 gene was observed a similar genotype distribution among leprosy patients and control subjects, and the genotypes G/G and G/A the most prevalent in both populations. There were also no significant differences between the allelic and genotypic frequencies among leprosy patients and healthy controls regarding the polymorphisms of the CD80 gene. Although CD80 and CD86 have important functions in the immune response data obtained in this study demonstrate that the analyzed polymorphisms do not influence the susceptibility to leprosy and/or different clinical forms of leprosy.
A hanseníase é uma doença infecciosa crônica causada pelo Mycobacterium leprae que é influenciada por aspectos genéticos do hospedeiro. Os pólos da hanseníase são ocupados por espectros imunológicos opostos, de um lado pela forma tuberculoide, com predominante resposta imunológica Th1 e do outro pela forma virchowiana, com predominante resposta Th2. Durante o desenvolvimento da resposta imune, além do sinal antígeno-específico é necessário um segundo sinal para ativação dos linfócitos T, denominado coestimulação. Este sinal pode ser fornecido pelas moléculas CD80 e CD86 presentes nas superfícies das células apresentadoras de antígenos. A ligação destas moléculas aos receptores CD28 e CTLA-4 presentes nos linfócitos T conduz à ativação ou à inibição da resposta imune, respectivamente. A baixa regulação de CD80 e CD28 em pacientes com hanseníase borderline virchowiana ou virchowiana pode ser responsável pela defeituosa sinalização de células T específicas para os antígenos de M. leprae pela via CD80/CD28. Isto pode levar à inativação clonal de células T reativas aos antígenos de M. leprae e, consequentemente, o bacilo cresceria sem restrição nos macrófagos. No presente trabalho foi investigada a possível relação entre polimorfismos presentes nos genes CD80 e CD86 com a susceptibilidade à hanseníase e/ou às formas clínicas da doença. A genotipagem dos polimorfismos foi realizada pelo método de sequenciamento direto. Foram analisados no gene CD80 seis SNP localizados na região promotora (-454 C/A, -387 T/C, -232 G/A, -79 C/G, -7T/C e +5C/A) e um polimorfismo de inserção/deleção (-557_-561 CATGA) e no gene CD86 foi analisado um SNP no éxon 8, posição +1057G/A. Quanto ao gene CD86 foi observada distribuição genotípica semelhante entre os pacientes e indivíduos controles, sendo os genótipos G/G e G/A os mais prevalentes em ambas as populações. Também não foram observadas diferenças significativas entre as frequências alélicas e genotípicas entre os pacientes com hanseníase e indivíduos controles referentes aos polimorfismos do gene CD80. Embora CD80 e CD86 tenham funções importantes na resposta imune os dados obtidos neste estudo demonstram que os polimorfismos analisados não têm influência na susceptibilidade à hanseníase e/ou diferentes formas clínicas da hanseníase.

The binding of CD80/CD86 on the APC to CD28 on the T cell surface provides a second signal for T cell activation. While it was once believed that this interaction represented a one-way signal, resulting in T cell activation, recently, it has been investigated as a bidirectional signaling process. CD80/86 activation produces IL-6 in DCs, but its role in macrophage activation is unknown. Dysregulation of CD80/86 expression has been observed in autoimmune disorders and cancer, and may also influence the development of immune responses including production of cytokines in response to stimulation with TLR-4 ligand, LPS. Therefore, the focus of my project was twofold: 1) to investigate the role of CD80/86 as signaling receptors capable of transmitting extracellular signals, and 2) to determine the TLR-4 activated pathways that regulate CD80/86 expression in human monocyte-derived macrophages (MDMs). Since I demonstrated that activation of CD80/86 alone did not induce expression of the four cytokines investigated, I hypothesized that CD80/86 synergizes with other signaling pathways. I show for the first time that CD80/86 activation synergizes with TLR-4 signaling to produce IL-27 and IL-10 in human MDMs. Since cIAPs play a key role in TLR-4-mediated signaling, I investigated their role in TLR-4- and CD80/86-activated production of IL-10 and IL-27. Degradation of IAPs by SMAC mimetics inhibited LPS-induced IL-10 and IL-27 production in MDMs. However, it did not alter the TLR-4 and CD80/86 synergistic effect on IL-10 and IL-27 production suggesting that IAPs may not play a role in CD80/86 activation of macrophages. Since I have demonstrated this role for IAPs, I extended my studies by examining the involvement of IAPs and other upstream signaling molecules such as SHP-1, RIP1, TRAF2, in modulating the LPS-induced CD80/86 expression. I showed that cIAP2, SHP-1, RIP1, TRAF2 co-localize to form a complex that regulates the LPS-induced CD80 and CD86 expression through AKT-activated p38 MAPK in human macrophages. These findings may lead to the development of novel therapeutic interventions in the treatment of autoimmune diseases.

Multiple Sclerosis (MS) is a chronic inflammatory and demyelinating disease of the central nervous system. The etiology of MS is unknown but many researchers believe that it is autoimmune mediated. This study investigated naive CD4+ and naive CD8+ T-cell homeostasis in patients with Primary Progressive Multiple Sclerosis and Relapsing Remitting Multiple Sclerosis. The naive T-cell compartment involves a balance between thymic production of naive T-cells, homeostatic proliferation and the delivery of death and survival signals. Naive T-cell production was quantified by measuring signal joint T-cell receptor excision circles (sj-TRECs); episomal byproducts formed during V(D)J T-cell receptor rearrangement.
Homeostatic proliferation was quantified by flow cytometry analysis of % expression of CD31 and Ki-67. CD31 is a marker found on CD4+ recent thymic emigrants (RTE) but not on naive T-cells that have undergone homeostatic proliferation. CD31 can be used as a marker of the proliferation history of naive CD4+ T-cells. Ki-67 is a nuclear and nucleolar antigen found in actively cycling cells. It can be used as a marker of cell proliferation at the moment of isolation. Cell survival was measured by quantifying plasma IL-7 levels and by measuring Bcl-2 expressions. IL-7 plays an important role in maintaining and restoring peripheral naive T-cell homeostasis. It stimulates naive T-cell proliferation and prevents the reduction of Bcl-2, an antiapoptotic protein.
In this study, PPMS patients had significantly reduced naive CD4 + T-cell sj-TRECs compared to healthy controls (p = 0.0007) and compared to RRMS patients (p = 0.0010). RRMS patients had fewer sj-TRECs than healthy controls but this difference was not significant (p = 0.4652). Similarly, in PPMS, naive CD4+ T-cells had significantly lower CD31 expression than healthy controls (p = 0.0017) and RRMS patients (p = 0.0032). This finding indicates increased homeostatic proliferation in naive CD4 + T-cells in PPMS, most probably a response to decreased thymic export as marked by the decreased naive CD4+ T-cell sj-TRECs. % CD31 expression in naive CD4+ T-cells did not differ significantly in RRMS compared to healthy controls (p = 0.7455) which is consistent with their naive CD4+ sj-TREC levels.
Naive CD8+ T-cell sj-TRECs were significantly reduced in PPMS patients compared to healthy controls (p = 0.0212) but not compared to RRMS patients (p = 0.2379). RRMS patients had fewer naive CD8 + T-cell sj-TRECs compared to healthy controls but this difference was not significant (p = 0.1517). PPMS patients expressed increased Bcl-2 levels in their naive CD8+ T-cells. This finding indicates upregulation of survival signals, most probably a consequence of reduced thymic export of naive CD8+ T-cells.
The data from this study indicate that PPMS is different from RRMS in their naive CD4+ T-cell sj-TRECs and naive CD4 + T-cell % CD31 expression but is similar to RRMS in their naive CD8+ T-cell sj-TRECs. This study concludes, therefore, that both PPMS and RRMS patients have altered naive T-cell homeostasis.

IL-6 is an inflammatory cytokine that contributes to the pathogenesis of many immunological diseases including rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, allergic asthma, as well as the protection against infections caused by various pathogens. These are linked to its role in regulating CD4 T cell differentiation and effector function. Most of these functions are dependent on the IL-6-mediated signaling through the transcription factor Stat3. In this thesis, we identify a novel molecular mechanism by which IL-6 regulates CD4 T cell effector function. We show that IL-6-dependent signal raises the levels of mitochondrial Ca2+ late during activation of CD4 T cells. This is further used to prolong the expression of effector cytokines IL-4 and IL-21. The modulation of mitochondrial Ca2+ is mediated by the regulation of mitochondrial Stat3 and the formation of respiratory supercomplexes. Thus, in addition to the canonical signaling of IL-6 through Stat3 as a transcription factor, IL-6 also modulates mitochondrial Stat3 to regulate mitochondrial function in CD4 T cells. This could be an alternative pathway by which IL-6 regulates effector function of CD4 T cells and it could contribute to the pathogenesis of inflammatory disease. Little is known about the effects of IL-6 on CD8 T cells. In this thesis, we reveal a paradigm-shifting mechanism by which IL-6 regulates antibody production by converting CD8 T cells into B cell helpers through IL-21. Briefly, IL-6 promotes the differentiation of a subset of naïve CD8 T cells into a unique population of effector CD8 T cells characterized by the production of high levels of IL-21. IL-21-producing CD8 T cells provide help to B cells to induce isotype switching and protective antibody production during infection. In summary, this thesis provides new insights into both mechanistic and functional aspects of IL-6 in regulating T cell function. These findings may shed light on the development of new therapeutic approaches in treating autoimmune disorders and preventing infectious diseases.

Mycobacterium tuberculosis (Mtb) causes human tuberculosis, and more people die of it than of any other pathogen in the world. Immunodominant antigens elicit the large majority of T cells during an infection, making them logical vaccine candidates. Yet, it is still unknown whether these immunodominant antigen-specific T cells recognize Mtb-infected cells. Two immunodominant antigens, TB10.4 and Ag85b, have been incorporated into vaccine strategies. Surprisingly, mice vaccinated with TB10.4 generate TB10.4-specific memory CD8+ T cells but do not lead to additional protection compared to unvaccinated mice during TB. Ag85b-specific CD4+ T cells are also generated during vaccination, but the literature on whether these cells recognize Mtb-infected cells is also inconsistent. We demonstrate that TB10.4-specific CD8+ T cells do not recognize Mtb-infected cells. However, under the same conditions, Ag85b-specific CD4+ T cells recognize Mtb-infected macrophages and inhibit bacterial growth. In contrast, polyclonal CD4+ and CD8+ T cells from the lungs of infected mice can specifically recognize Mtb-infected macrophages, suggesting macrophages present antigens other than the immunodominant TB10.4. The antigen location may also be critical for presentation to CD8+ T cells, and live Mtb may inhibit antigen presentation of TB10.4. Finally, we propose that TB10.4 is a decoy antigen as it elicits a robust CD8+ T cell response that poorly recognizes Mtb-infected macrophages, allowing Mtb to evade host immunity.

The initiation of adaptive immune responses requires the interactions of T cells with antigen presenting cells (APC) in the context of an immunological synapse (IS). Naive T cell responses are dependent on the engagement of CD28 and CTLA-4 by CD86 and CD80, respectively amplifying and dampening the antigen specific signal. CD80 and CD86 cosignaling molecules display three major domains: a membrane distal IgV-like domain, a membrane proximal IgC-like domain and an intracellular domain. Crystallographic data has shown that only the IgV domain of CD80 and CD86 physically interacts with CTLA-4. However, extensive mutational analyses have also implicated the IgC domain in receptor binding and in the overall function of these molecules. The role of CD80 and CD86 within the IS and their exact molecular structure remains to be elucidated. The work presented in this thesis employs wild type, mutant, deleted and chimeric forms of CD80 and CD86 to characterize the role of their domains in molecular structure, receptor binding and overall cosignaling function in an antigen specific cellular interaction system. CD80 and CD86 are shown to be associated to the AFC cytoskeleton. A highly conserved K4 motif within CD86 is shown to be a cytoskeletal association motif. Moreover, CD86 is shown to physically interact with ERM proteins. Only cytoskeleton-linked CD86 localizes at the IS and induce IL-2 production. CD80 and CD86 molecular organization is clearly established using cytometry-based fluorescence resonance energy transfer (FCET) and biochemical approaches. CD80 exists as a mixed monomeric and dimeric population and CD86 as a monomer in live cells. The crucial role of CD80 and CD86 IgC domain in multimerization is revealed. Importantly, the molecular structure of these molecules correlates with their binding properties and cosignaling function. A functional picture of CD80 and CD86 domains emerges where the IgV is responsible for receptor binding, the IgC domain impacts dimerization, and the intracellular domain functionally links these proteins to the cytoskeleton. The findings presented in this thesis certainly contribute to the general understanding of cosignaling protein interactions and functions and may facilitate the design of structure-based immunotherapeutics.

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INTRODUCTION:The Acquired Immunodeficiency Syndrome (Aids) comes along the years promoting inversion of the relation men/women in the age group of 13 to 19 years, committing mainly the reproductive life phase women. The sexuality, inherent upon human being, has in the expression of satisfaction of the sexual performance the possibility of providing several benefits in the quality of life of people, such as increase of the longevity, among others. In women living with Aids the main marker of immunity are the CD4+ T lymphocytes used for evaluating the need of antiretroviral therapy (ARVT). OBJECTIVE: Showing up the association between the CD4 count and the sexual performance of women living with Aids in Imperatriz city. METHODOLOGY: cross-sectional study, carried out in the period of march, 2014 to december, 2014, in which it was selected women with diagnosis of Aids, using ARVT at least six months before interview, originating from the Specialized Aids Service (SAS), registered in the Medicines Logistic Control System - SICLOM, of Imperatriz town. They were included those women older than 18, who related having sexual practice before the diagnosis of Aids, capable of communicating, without any cognitive deficit. The facts about the socio-demographic and behavioral variables, clinical factors related to co-morbidities were recorded in own form, right away they answered the Female Sexual Function Index (FSFI) questionnaire. The sample was based in the quantitative of women registered in the SICLOM of Imperatriz Town, sampling error of 5%, confidence interval (CI) of 95%, alpha value ≤ 5%. The chisquare test was used to evaluate the association between the variables, so the Kruskal- Wallis test when necessary. The test of Spearman was utilized for showing the correlation between the relation CD4/CD8 and FSFI. RESULT: the sample included 149 women, it was noted that the larger FSFI score means and medians coincided with the highest means of CD4 T- lymphocyte count from the 2rd quartile (Kruskal Wallis test, p = 0.0347), and there was a positive association between FSFI and the CD4 / CD8 ratio (p = 0.0264), confirming the alternative hypothesis (Spearman correlation). CONCLUSION: It was concluded there is a positive association between the sexual performance and CD4 count.
INTRODUÇÃO: A Síndrome da Imunodeficiência Adquirida (Aids) vem ao longo dos anos promovendo inversão da relação homem/mulher na faixa etária de 13 a 19 anos, comprometendo principalmente as mulheres na fase de vida reprodutiva. A expressão de satisfação no desempenho sexual possibilita proporcionar vários benefícios na qualidade de vida como o aumento da longevidade. Na Aids o principal marcador de imunidade são os linfócitos T-CD4, usados para avaliar a necessidade de terapia antirretroviral (TARV). OBJETIVO: identificar associação da concentração dos linfócitos T-CD4 e o desempenho sexual das mulheres com Aids do município de Imperatriz. METODOLOGIA: estudo transversal realizado de março a dezembro de 2014 com mulheres provenientes do Serviço de Assistência Especializada (SAE) cadastradas no Sistema de Controle Logístico de Medicamentos (SISCLOM) com diagnóstico de Aids no município de Imperatriz. Foram selecionadas aquelas em TARV há pelo menos seis meses, com 18 anos ou mais, que relataram prática sexual antes do diagnóstico de Aids e capazes de se comunicar. As variáveis sócio demográficas e comportamentais de interesse, fatores clínicos relacionados à presença de comorbidades foram registrados em formulário próprio. A seguir para avaliação do desempenho sexual responderam o questionário Female Sexual Function Index (FSFI). Ambos foram respondidos concomitantemente à coleta de sangue para contagem de linfócitos T, realizada no laboratório do SAE duas vezes por semana. A amostra representativa baseou-se no quantitativo de mulheres cadastradas no SICLOM, com erro amostral de 5%, intervalo de confiança de 95% e valor de alfa ≤ 5%. Foram utilizados os testes Qui-Quadrado para avaliar a associação entre as variáveis, e quando necessário o de Kruskal- Wallis, o teste de Spearman para avaliar a correlação entre CD4/CD8 e FSFI. RESULTADOS: a amostra constou 149 mulheres incluídas, notou-se que as maiores média e mediana do escore do FSFI coincidiram com as maiores médias da contagem de Linfócitos T- CD4 a partir do 2º quartil (Teste de Kruskal Wallis p=0,0347), e houve associação positiva entre FSFI e a relação CD4/CD8 (p=0,0264), confirmando a hipótese alternativa (Correlação de Spearman). CONCLUSÃO: houve associação positiva entre o desempenho sexual ou atividade sexual, com ou sem camisinha, com a contagem de linfócitos T-CD4 e relação CD4/CD8.

A gengivite crônica e intratável observada em gatos infectados pelo vírus da imunodeficiência felina (FIV) é um problema bastante freqüente na clínica de pequenos animais. O papel do FIV na etiologia da estomatite persistente ainda está por ser determinado. As manifestações orais são freqüentemente os primeiros sintomas observados em pacientes humanos infectados pelo HIV e podem ser usadas como indicadores da progressão da doença. O objetivo do presente estudo foi quantificar os linfócitos T CD4+, T CD8+ e a razão CD4+/CD8+ em uma colônia de gatos com gengivite crônica e naturalmente infectados pelo FIV. Para tanto, foram utilizados 20 gatos, todos apresentando gengivite com graus variando de 1 a 4. Desse total, 10 gatos não eram infectados pelo FIV e os outros 10 felinos eram infectados pelo FIV. Utilizou-se como controle 20 gatos sem gengivite, sendo 10 infectados pelo FIV e outros 10 não infectados pelo Retrovírus. As contagens dos linfócitos T CD4+ e CD8+ foram realizadas utilizando-se a técnica de citometria de fluxo. Os resultados obtidos demonstraram que os gatos com gengivite e infectados pelo FIV apresentaram uma contagem significativamente menor de linfócitos T CD4+ quando comparado aos gatos com gengivite e não infectados pelo FIV. Não houve diferença significativa na contagem de linfócitos T CD8+ entre os gatos com gengivite, infectados ou não pelo FIV. A razão CD4+/CD8+ também se mostrou em declínio nos gatos com gengivite e infectados pelo FIV. Concluiu-se que nas condições do presente estudo, a infecção pelo FIV compromete a resposta imunológica de felino diante da inflamação gengival.
Chronic and intractable gingivitis in FIV-infected cats is a relatively common clinical problem in veterinary practice. The role of FIV in the etiology of persistent stomatitis is still undetermined. Oral manifestations often found in HIV-infected people are frequently the first clinical sign of the infection and can be considered as an indicator of the progression of the HIV infection. The purpose of this study was to evaluate the CD4+ and CD8+ T-lymphocytes count and CD4+:CD8+ ratio in a colony of cats with chronic gingivitis. To achieve these goals, a colony of twenty domestic shorthair cats was used. All cats had some degree of gingival inflammation with scores ranging from 1 through 4. Ten cats were FIV-positive and ten were FIV-negative. As a control, twenty cats without gingivitis were used (ten cats were FIV-positive and ten were FIV-negative). CD4+ and CD8+ T-lymphocytes counts were performed by means of flow cytometry in all forty cats and results compared. The results showed that cats with gingivitis and FIV-infected had a lower CD4+ T cells count than cats with gingivitis but not FIV-infected. There was no difference in CD8+ T lymphocytes count among the cats with gingivitis infected or not with the FIV. The CD4+:CD8+ ratio was lower in cats with gingivitis and FIV-infected. One can conclude that FIV infection induces immunological disorders in cats with gingival inflammation.

A cromoblastomicose é uma infecção fúngica subcutânea causada por fungos da família Dematiceae sendo o principal agente etiológico o fungo Fonsecaea pedrosoi (F. pedrosoi). Estes fungos induzem uma lesão crônica na pele de freqüente recidivas. O objetivo do trabalho foi avaliar alguns aspectos imunológicos na cromoblastomicose experimental através de dois modelos de infecção pelas vias: intraperitoneal (i.p.) e subcutânea (s.c.). No primeiro modelo de infecção pela via s.c. em camundongos BALB/c infectados com 106 conídios de F. pedrosoi, ocorreu a cura espontânea da infecção em aproximadamente 4 semanas. Na subtipagem de linfócitos T em linfonodos regionais ocorreu um predomínio de células T CD4+ que foi constante até a 4ª semana de infecção, no entanto, observamos aumento significativo de linfócitos T CD8+ ao longo da infecção sugerindo que essa população tenha também uma importante participação no controle da doença. Os ensaios de linfoproliferação demonstraram, na 1ª semana de infecção, elevado índice de proliferação celular quando as células de linfonodos foram estimuladas in vitro com antígenos de F. pedrosoi, além da liberação principalmente da citocina IFN-γ, já na 4ª semana de infecção não foi detectado proliferação celular. Esses resultados sugerem que no início da infecção a resposta celular seja mediada principalmente por linfócitos T CD4+ produtores de IFN-γ, o que nos sugere, que neste modelo experimental, polarize uma resposta de células T do tipo Th1. No segundo modelo de infecção, via intraperitoneal (i.p.), camundongos BALB/c infectados com 106 conídios de F. pedrosoi mostraram desenvolvimento de infecção crônica com preservação da imunidade celular mesmo após a 8ª semana. Ainda pela via i.p., os camundongos C57BL/6 nocautes de T CD4+ apresentaram uma maior carga fúngica no início da infecção e em tempos mais tardios a carga fúngica foi semelhante aos camundongos controles (C57BL/6); esses mesmos animais nocautes não apresentaram uma ativação da resposta celular medida pelo teste de HTT (Hipersensibilidade do Tipo Tardio). Quando avaliamos o padrão de citocinas, a citocina IFN-γ produzida pelos órgãos baço e fígado apresentou menores níveis no início da infecção quando comparado ao camundongos controle. Já os níveis de IL-10 aumentaram gradativamente ao longo da infecção e IL-4 não apresentou diferenças em relação ao controle. Nos camundongos nocautes para coa (C57BL/6 CD8 \"KO\"), a carga fúngica, os níveis de citocinas e o teste de HTT foram semelhantes aos animais controle. Esses resultados mostraram que pela via i.p. os linfócitos T, principalmente células T CD4+ são importantes no controle inicial da infecção. Em tempos mais tardios a infecção foi controlada mesmo em camundongos deficientes de linfócitos TCD 4+ ou T CD8+, sugerido que outras células como macrófagos ou NK, estariam atuando de forma mais efetiva no controle da infecção.
Abstract not available.

CD4+ and CD8+ T cells, the essential mediators of cellular immune responses, are produced in the thymus following sequential maturation stages. Hematopoietic progenitors first seed the thymus and make T cell lineage specification and commitment decisions within the CD4−CD8− double negative (DN) compartment. Thymocytes then mature to the CD4+CD8+ double positive (DP) stage, followed by vigorous negative and positive selection processes. The positively selected DP thymocytes first give rise to CD4+CD8lo intermediate (IM) cells which then differentiate into MHC class II-restricted CD4+ and MHC class I-restricted CD8+ T cells, a crucial decision known as CD4+ vs. CD8+ lineage choice. The lineage choice decision is influenced by the timing, intensity, and duration of signals derived from the TCR and cytokines, and recent studies have identified a number of transcriptional factors that intrinsically regulate this critical fate decision. Among these, Th-POK (encoded by Zbtb7b, called Thpok here for simplicity and consistency with the literature) is specifically required for CD4+ differentiation while Runx factors promote CD8+ T cell production and repress Cd4 in CD8+ lineage committed cells. Upregulation of Thpok is most evident in the CD4+8lo IM cells and is required to antagonize Runx3 activity and expression to promote CD4+ lineage commitment. Collectively, the Th-POK-Runx3 axis appears to be a critical convergence point in the CD4+ vs. CD8+ lineage choice. After committing to either CD4+ or CD8+ thymocytes, lineage-inappropriate genes are silenced to ensure the distinct identity and functional divergence between these two cell types. Repression of the Cd4 gene on CD8+ lineage committed cells is mediated by a ~430 bp silencer sequence in its first intron. Likewise, Thpok is repressed in CD8+ T cells by a ~560 bp sequence upstream of the Thpok exon 1a, and both Cd4 and Thpok silencers contain consensus binding motifs for Runx factors, which are necessary for CD8+ lineage commitment. T cell factor 1 (TCF-1) and lymphoid enhancer binding factor 1 (LEF-1) are members of the TCF-LEF family transcription factors and abundantly expressed in T lineage cells, and known to be necessary for the maturation of DN T cells to the DP stage. However, because germline deletion of TCF-1 and LEF-1 causes severe early T cell developmental block and embryonic lethality, respectively, their roles beyond the DP stage are unknown. In my thesis work, I overcame these obstacles by conditionally ablating both TCF-1 and LEF-1 in DP thymocytes using CD4-Cre. We observed impaired differentiation of CD4+ T cells from the bipotent DP precursors in the absence of TCF-1 and LEF-1. Mechanistically, TCF-1 promotes CD4+ T cell development by positively regulating the expression of Thpok. TCF-1 and LEF-1 deficiency also results in derepression of the CD4 co-receptor in CD8+ lineage committed cells. In CD8+ T cells, TCF-1 interacts with Runx3 to repress expression of Cd4. These findings not only broaden the spectra of TCF-LEF-mediated regulatory activities in late stages of T cell development, but also reveal new paradigms in T cell fate decision and identity maintenance.

Orientador : Prof. Dr. Silvio Marques Zanata
Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Ciencias Biológicas (Microbiologia, Parasitologia e Patologia Básica). Defesa: Curitiba, 14/08/2015
Inclui referências : f. 81-95
Área de concentração
Resumo: Em um ramo novo da ciência como a imunologia, poucos modelos são capazes de resistir por tanto tempo quanto o modelo de sinalização dupla, proposto por Bretcher e Cohn em 1970. Atualmente, entende-se que a dupla sinalização atua de forma sinérgica para a ativação dos linfócitos T e que a via do CD28 é apenas uma parte de uma grande rede de controle incluindo diversas outras vias que atuam em conjunto para controlar a ativação de linfócitos. Tanto do ponto de vista funcional, assim como do ponto de vista estrutural, a abordagem da via de CD28-CD80/86 na maioria dos casos tem um enfoque sobre a via de ativação de linfócitos, a qual é bastante descrita enquanto as APCs aparecem apenas como coadjuvantes nessa interação. Essa perspectiva começou a mudar em 2004 quando foi descrito que células dendríticas de camundongo, quando estimuladas com LPS e CD28 sofrem uma ativação e iniciam a secreção de interleucinas. Num contexto no qual o efeito das vias de sinalização sobre os APCs começa a ser compreendido, torna-se importante o estabelecimento de modelos adequados a esse estudo. Frangos são um modelo clássico para o estudo em imunologia, desde o início do desenvolvimento desse campo de conhecimento. Não foi descrita na literatura, até o momento, a sinalização CD28-CD80/86 em macrófagos de aves, as quais podem apresentar diferenças fisiológicas e funcionais quando comparadas às de mamíferos. Desta forma, este estudo pretende estabelecer se os mecanismos de sinalização reversa presentes em mamíferos e aves foi conservado durante a evolução, avaliando ainda a hipótese de que macrófagos possam ser artífices da sinalização reversa, fato observado apenas para células dendríticas. Este trabalho tem como objetivo avaliar a ativação de macrófagos de frango frente ao estímulo com CD28 recombinante. Às células previamente estimuladas com LPS, foram adicionados meios de cultivo com LPS, CD28 e CD28 deletada (com uma deleção em seu sítio MYPPPY de ligação com CD80/86) e os estímulos mensurados através de qPCR para diversas citocinas em diferentes tempos experimentais. Para o primeiro estimulo com LPS, houve uma redução na produção de IL-4, IL-2 e IFN-? e uma alteração sugerida para a expressão reduzida de IL-6, IL-12, IL-1? e aumentada de TNF?. Na segunda estimulação apenas com LPS, pode-se concluir que o ambiente resultante é pró-inflamatório, uma vez que a expressão das interleucinas com características anti-inflamatórias, IL-4 e IL-10, está diminuída ou ausente, enquanto IL-2, IL-18 e IL-12 estão aumentadas. Sugere-se que o estimulo com CD28 produz uma ativação de macrófagos que tem característica pró-inflamatória, porém sem direcionamento M1 ou M2. Essa polarização provavelmente advém de uma interação com os outros atores do sistema imune por diversos mecanismos de troca de informação, como citocinas, quimiocinas e outras moléculas sinalizadoras. Este trabalho mostrou pela primeira vez o mecanismo de sinalização reversa mediado por células apresentadoras de antígeno profissionais em macrófagos de aves. Palavras-chave: imunologia; aves; gallus; macrófago; CD28; sinalização reversa; citocinas.
Abstract: In a new branch of science such as immunology, just a few models are able to resist for as long as the dual signaling model proposed by Bretcher and Cohn in 1970. Currently, it is known that the double signaling acts synergistically to activate T lymphocytes and that the path of CD28 is only one part of a large network control including several other ways that work together to control the activation of lymphocytes. In a functional point of view as well as from a structural point of view, the approach of CD28-CD80 / 86 in most cases has a focus on the activation pathway of lymphocytes, which is detailed described as the APCs appear only with a secondary role in this interaction. This perspective started to change in 2004 when it was reported that mouse dendritic cells when stimulated with LPS and CD28 undergoes activation and start to secrete interleukins. In a context that the effect of signaling pathways on APCs begins to be understood, it is important to establish suitable models in this study. Chickens are a classic model for the study in immunology, since the beginning of development of this field of knowledge. It has not been described in so far, CD28-CD80/86 signaling in avian macrophage, which may have physiological and functional differences compared to mammal ones. Thus, this study aims to establish if the mechanisms of reverse signaling present in mammals has been conserved during evolution and is similar in birds, also evaluating the hypothesis that macrophages can be passive of reverse signaling, which was observed only for dendritic cells. This project aims to evaluate the activation of chicken macrophages front of the stimulation with recombinant CD28. The cells previously stimulated with LPS, received culture media containing LPS, CD28 and deleted CD28 (with a deletion on the MYPPY CD80/86 binding site) the stimuli was measured by qPCR for different cytokines under different experimental times. For the first stimulation with LPS, there was a reduction in the production of IL4, IL2 and IFN-? and a modification on the expression was suggested with an increase for IL6, IL12, IL-1? and decreased for TNF. In the second stimulation with LPS, one may conclude that the resulting environment was pro-inflammatory, since the expression of interleukins with anti-inflammatory characteristics, IL-4 and IL-10, is decreased or absent, while IL-2 IL-18 and IL-12 are increased. It is suggested that CD28 stimulation generate an activation of macrophages that has pro-inflammatory characteristic but without polarization M1 or M2. This bias probably comes from an interaction with other actors of the immune system through several mechanisms of signaling such as cytokines, chemokines, and other signaling molecules. This study showed for the first time the reverse signaling mechanism mediated by professional antigen presenting cells in avian macrophage. Key words: immunology; birds; gallus; macrophage; CD28; reverse signaling; cytokines.

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Eosinophils are a hematopoietic cell originated from precursor cells found in bone marrow, whose differentiation and proliferation is regulated by cytokines such as GM-CSF, IL-3 and IL-5. When activated, eosinophils are capable of phagocytosis of small particles and bacteria, but their main form of activity in the inflammatory process is the release of toxic proteins, cytokines, enzymes, lipid mediators and reactive oxygen products. The increase in eosinophil is an important feature in many diseases such as allergy and parasitic infections. Provided APC (Antigen-Presenting Cells), eosinophils are considered similar to the CD (Dendritic Cells) in its potential to activate naïve T cells and may have potential as efficient as the CD in stimulating lung T cells in the upper airways in the model inflammation. The APC are defined by being able to take, processing and presenting antigen such as CD, macrophages, B lymphocytes and possibly eosinophils. The surface expression of APC is characterized by coestimatórias molecules CD80 (B7-1) and CD86 (B7-2) and also by MHCII. The proposed model for this evaluation was to Visceral Larva Migrans syndrome (VLMS) caused by Toxocara canis, one of the most frequent helminth in young dogs. One of the main consequences of this infection is the marked increase in circulating and tissue eosinophils. Eosinophilia has been associated with parasitic diseases particularly when the parasite invades or promotes tissue damage at mucosal surfaces In the present study we evaluated the expression of MHC II and CD80 and CD86 molecules coestimulatórias in eosinophils in VLMS. Our results showed that the molecules studied were expressed in eosinophils in the blood of mice infected with Toxocara canis compared with the control group. Correlating an intense eosinophil still during the course of the disease with increased IL-5 in the infected group. Suggests that during the course of Toxocara canis, eosinophils can exhibit behavior of an APC, increasing the expression of MHCII molecules coestimulatorias and possibily amplifyng the immune response in this model.
O eosinófilo é uma célula hematopoiética, originada a partir de células precursoras presentes na medula óssea, cuja diferenciação e proliferação são reguladas por citocinas como GMCSF, IL-3 e IL-5. Quando ativados, os eosinófilos são capazes de realizar fagocitose de pequenas partículas e bactérias, mas sua principal forma de atuação no processo inflamatório consiste na liberação de proteínas tóxicas, citocinas, enzimas, mediadores lipídicos e produtos reativos de oxigênio. O aumento no número de eosinófilos é uma característica importante em diversas doenças como a alergia e as infecções parasitárias. Na condição de APC (Células Apresentadoras de Antígenos), os eosinófilos são considerados similares as CD (Células Dendríticas) em seu potencial para ativar células T naïve, podendo ter potencial tão eficiente quanto as CD pulmonares em estimular células T nas vias aéreas superiores no modelo da inflamação. As APC são definidas por serem capazes de ingerir, processar e apresentar o antígeno como: CD, macrófagos, linfócitos B e possivelmente os eosinófilos. A expressão na superfície da APC é caracterizada por moléculas coestimatórias CD80 (B7-1) e CD86 (B7-2) e ainda pelo MHCII. O modelo proposto para esta avaliação foi a Síndrome da Larva Migrans Visceral (SLMV) causada pelo Toxocara canis, um dos helmintos mais freqüentes em cães jovens. Uma das principais consequências desta infecção é o aumento marcante de eosinófilos circulantes e teciduais. A eosinofilia tem sido associada com doenças parasitárias particularmente quando o parasita invade os tecidos ou promove danos na superfície das mucosas. No presente estudo avaliamos a expressão de MHC II e moléculas coestimulatórias CD80 e CD86 em eosinófilos na SLMV. Nossos resultados mostraram que as moléculas analisadas foram expressas em eosinófilos no sangue de camundongos infectados com Toxocara canis quando comparado com o grupo controle. Correlacionando ainda uma intensa eosinofilia durante o curso da doença com o aumento de IL-5 no grupo infectado. Sugere que, durante o curso da infecção pelo Toxocara canis, eosinófilos podem apresentar comportamento de uma APC, aumentando a expressão de moléculas coestimulatórias e MHCII e possivelmente amplificando a resposta imune nesse modelo.