The aim of our study was to simulate in rats all aspects and techniques used in our new clinical program of cryopreserved alloarterial transplantation and investigate the influence of two immunosuppressive protocols with tacrolimus on acute rejection of these allografts. Cryopreserved abdominal aortic grafts were transplanted between Brown-Norway and Lewis rats. Tacrolimus (0,2 mg/kg daily) was administered from day 1 to day 30 (TAC1) or from day 7 to day 30 (TAC7), respectively. No immunosuppressed isogeneic (ISO) and allogeneic (ALO) rats combination served as control. Aortal wall destruction and infiltration by immunocompetent cells (MHC II+ cells of recipient origin) was studied on day 30 after transplantation. Flow cytometry was used for the analysis of day 30 sera for the presence of donor specific anti-MHC class I and II antibodies. The aortal allografts in both immunosuppressed groups showed regular morphology of aortal wall with no depositions of immunoglobulin G on day 30. The adventitial infiltration of non-immunosuppressed aortal allografts by MHC class II positive cells of recipient origin was significantly higher (ALO 20,7±6,7 cells, P <0,001) compared to both immunosuppressed groups (TAC1 5,9±5,5 cells, TAC7 6,1±5,1 cells). Anti-MHC antibodies class I and II level in peripheral blood...

Immunologic self-tolerance is maintained by both central and peripheral mechanisms. Furthermore, regulation of mature lymphocyte responses is governed by inhibitory as well as stimulatory signals. TCR recognition of cognate peptide bound to MHC molecules provides the initial stimulus leading to T lymphocyte activation and determines the antigen specificity of any subsequent response. However, lymphocytes must discriminate between foreign and self antigens presented by self-MHC molecules to maintain self tolerance and avoid pathological autoimmunity. Consequently, TCR ligation alone is reported to result in abortive activation, T cell anergy, apoptosis, and tolerance. Under normal physiological conditions, costimulatory signals modify lymphocyte responsiveness to TCR ligation to prevent autoimmunity while enabling robust responses to foreign antigen. Members of the CD28/B7 superfamily provide the critical secondary signals essential for normal immune cell function. CD28 is an essential positive costimulatory molecule with critical functions in thymic development, lineage commitment, and regulation of peripheral lymphocyte responses to antigenic stimuli. CD28 ligation by APC-expressed B7 molecules alters proximal signaling events subsequent to MHC/TCR interactions, and initiates unique signaling pathways that alter mRNA stability and gene transcription. Furthermore, CD28 signaling is required for regulatory T cell development and function. Thus, CD28 has a central role in both potentiating lymphocyte activation mediated by TCR engagement and regulating peripheral tolerance. In contrast, Ctla-4 mediates an inhibitory signal upon binding B7 molecules on an antigen-presenting cell. Its importance in governing lymphocyte responses is manifested in the fatal lymphoproliferative disorder seen in Ctla-4-/- mice. The lymphocyte proliferation is polyclonal, antigen and CD28 dependent, and arises from defects in peripheral CD4+T cell regulation. The high percentage of peripheral T lymphocytes expressing activation markers is accompanied by lymphocyte infiltration into numerous non-lymphoid tissues and results in death by 3-4 weeks. While still controversial, Ctla-4 signaling has been reported to be essential for induction of peripheral T lymphocyte tolerance in vivo and in some model systems is proposed to regulate both T lymphocyte anergy induction and the immune suppressive effects of some regulatory T cells in the prevention of autoimmunity. Signaling pathways activated by TCR ligation and CD28 costimulation have been extensively characterized. In contrast, the mechanisms mediating Ctla-4 maintenance of tolerance remain largely unknown. Ctla-4 gene expression is tightly controlled during T cell development and activation, and its intracellular localization and expression on the cell surface is regulated by numerous pathways and intermediates. While a tailless Ctla-4 mutant is capable of inhibiting T cell activation, recent studies have shown that a ligand independent form of Ctla-4 is also capable of providing an inhibitory signal to T lymphocytes. In conjunction with the strictly controlled expression kinetics and the perfect amino acid homology between the intracellular domains of mouse and human Ctla-4, this data suggests that Ctla-4 may participate in the modulation or initiation of intracellular signaling pathways. Positive and negative costimulatory receptors on the T cell modify lymphocyte responses by altering both quantitative and qualitative aspects of the lymphocyte response including threshold of activation, cytokine secretion, and memory responses. Positive costimulation augments T cell responses, in part, by downregulating the expression of genes that actively maintain the quiescent phenotype. This study was initiated to determine the role of Ctla-4 ligation in modifying the global gene expression profile of stimulated T cells and to determine if the Ctla-4 mediated maintenance of T cell tolerance was achieved, in part, by altering the transcription of quiescence genes necessary for the prevention of T cell activation subsequent to TCR and CD28 stimulation. Previous studies investigating the influence of Ctla-4 ligation on transcriptional profiles of activated lymphocytes detected only quantitative alterations in the transcriptional regulation initiated by CD28 signaling. In contrast, our data suggests that quantitative effects of Ctla-4 ligation that differentially influence pathways acting downstream of stimulatory receptors results in a stable and qualitatively unique phenotype detectable at the level of the transcriptome. Thus, the cumulative effect of Ctla-4 signaling is unique and not constrained to reversing alterations in expression initiated by CD28. In addition, Ctla-4 ligation can be shown to influence T lymphocyte responsiveness and the resulting global expression profile within 4 hours after stimulation and prior to detectable Ctla-4 surface expression. In a subpopulation of T cells, TCR stimulation activates pathways that result in commitment to activation with 2-6 hours. In contrast, CD28 signaling must be maintained for 12-16 hours to ensure maximal responses at the population level. The period of sensitivity to Ctla-4 inhibition of activation is more constrained and does not extend beyond 12 hours. Together, these data support a potential role for Ctla-4 in modification of the early transcriptional response and may explain various alterations in phenotype resulting from Ctla-4 ligation that have been reported in secondary responses. Identification of genes involved in lymphocyte activation, maintenance of selftolerance, and attenuation of immune responses opens the door to therapeutic manipulation of the pathways implicated. CD28 costimulation results in general amplification of TCR-initiated transcriptional responses, and specifically alters the expression profile of a subset of genes. In contrast, Ctla-4 ligation directly and specifically alters the expression of a select group of genes when ligated, and results in minimal suppression of the global CD28-mediated costimulatory transcriptional response. Ctla-4 regulated genes comprise a heterogeneous family, but include known quiescence factors, transcriptional regulators, and various determinants of cell cycle progression and senescence. The role of Ctla-4 in maintaining self-tolerance indicates that targeted manipulation of these gene products presents a novel therapeutic opportunity, and suggests that the mechanisms involved in Ctla-4-mediated maintenance of peripheral T cell tolerance and regulation of immune responsiveness is more nuanced than previously thought. In addition, this study provides the most comprehensive description of global gene expression during primary lymphocyte activation yet available. The integration of statistical and bioinfomatics analyses with large scale data mining tools identifies genes not previously characterized in lymphocytes and can direct future work by predicting potentially interacting gene products and pathways.

This thesis is comprised of studies of proteins involved in class I and class II major histocompatibility complex (MHC) antigen procressing. In class I MHC processing, structural and functional studies were conducted of an aminopeptidase, ERAP1, that mediates the final step in antigen processing to understand how it is particularly suitable for cleavage of antigenic peptides for class I MHC presentation. In the class II MHC antigen presentation pathway, structural studies were conducted to characterize a fluorogenic peptide that can be used to understand peptide loading events in vivo and in real time. Also structural studies of class II MHC and peptide complexes were conducted to understand the nature of an unique C-terminal secondary structure element exhibited by an HIV derived peptide in the peptide binding groove of class II MHC. The studies discussed in this thesis provide insights into the proteins involved in the class I and class II MHC antigen presentation pathway. The endoplasmic reticulum (ER) aminopeptidase, ERAP1, is a 941 amino acid member of the M1 family of zinc metalloaminopeptidases. Unlike other aminopeptidases, ERAP1 has a length and C-terminal preference for its substrates. Interestingly, ERAP1 has been shown to trim antigenic peptides to lengths of 8 or 9 amino acids long. This length matches the length required to bind into the peptide binding groove of class I MHC molecules. In addition, ERAP1 is upregulated in the ER of cells treated with interferon gamma (IFN-γ). Knock-down of ERAP1 by siRNA results in less overall antigenic presentation during IFN-γ treatment, although the knock-down does not affect all class I MHC epitopes equally. Knock-out studies show that ERAP1 effects the antigen repertoire at the cell surface. These and other data implicate ERAP1 as an important player in class I MHC antigen presentation. A chapter of this thesis will describe the crystallographic work describing the structures of ERAP1 with an aminopeptidase inhibitor, bestatin, and ERAP1 without an inhibitor that suggest possible peptide binding site in ERAP1 that will allow it to generate suitable substrates for a subset of class I MHC alleles. Class II MHC plays a key role in the immune response by presenting antigenic peptides on CD4+ cytotoxic cell surfaces for T-cell response. The binding of peptides onto the MHC is an important step in creating an immune response. Structures of peptide bound MHC class II show conserved side chain binding pockets within the overall peptide-binding groove. In HLA-DR1, a common human class II MHC, the P1 pocket shows a preference for large hydrophobic side chains. Development of environmentally sensitive peptide analogs, that can bind into the class II MHC the same way as native peptides, can assist in visualizing the antigen binding process. A chapter in this thesis describes the crystallographic work showing that (4-DAPA)-HA can be used to study antigen-presenting processes in a cell by visualizing the changes in fluorescence of the synthesized peptide upon antigen loading. Crystallographic analysis of MHC class II, HLA-DR1, in complex with HIV gag-derived peptide, GagP16(PEVIPMFSALSEGATP), and superantigen, SEC3- 3B2, reveals the conventional polyproline conformation up to MHC binding pocket residue, P9, while the C-terminus of GagP16 adopts an unusual β- hairpin loop structure. Additionally, interactions between the leucine at P8 (LeuP8) and other residues on the loop such as ThrP16 and AlaP14 of the hairpin loop, was observed. Importantly, GagP16 requires the last 4 amino acids (P13-P16), which is part of the hairpin loop, for T-cell recognition. Understanding what dictates the C-terminal hairpin loop and the interaction motif of HLA-DR1/GagP16 complex with its TCR will provide insights on why it is important for T cell activation. A chapter in this thesis discusses the structural investigation conducted to understand the determinants of the loop at the C-terminus of GagP16 using designed peptides. It will also discuss work involving HLA-DR1 with the T cell receptor, AC25, that was cloned from T cells that are specific to HLA-DR1 in complex with the GagP16 peptide.

La chaîne invariante (Ii) agit à titre de chaperon dans l’assemblage et le trafic des molécules du complexe majeur d’histocompatibilité de classe II (CMHII). Chez l’humain, les deux isoformes prédominantes, p33 et p35, diffèrent par la présence d’un motif di-arginine (RXR). Ce dernier permet la rétention de p35 au réticulum endoplasmique (RE) jusqu’à son masquage par une molécule de CMHII. La chaîne invariante forme des trimères auxquels s’associent successivement jusqu’à trois dimères αß de CMHII résultant en la formation de pentamères, heptamères et nonamères. Toutefois, la stœchiométrie exacte des complexes Ii-CMHII qui quittent le RE et le mécanisme permettant le masquage du motif RXR demeurent un sujet de débats. Dans un premier temps, nous avons examiné par une approche fonctionnelle la stœchiométrie des complexes formés autour de p33 et de p35. Nous avons observé que p35 engendre la formation de complexes nonamériques (αßIi)3 et permet l’incorporation de différents isotypes de CMHII autour d’un même trimère de p35 alors que p33 facilite la formation de pentamères (αß)1Ii3. Lors de l’étude du masquage du motif RxR par les CMHII, nous avons montré que son inactivation requiert une interaction directe (en cis) entre les sous-unités p35 et CMHII, résultant en une rétention des trimères de p35 insaturés au RE. Aussi, nous avons observé que contrairement aux complexes p33-CMHII, les complexes p35-CMHII sont retenus au RE lorsque coexprimés avec la protéine NleA de la bactérie Escherichia coli entérohémorragique. Comme l’expression de NleA interfère avec la formation des vésicules COPII responsable de l’export du RE, nous supposons que la sortie du RE des complexes p35-CMHII dépend des vésicules COPII alors que la sortie des complexes formés autour de l’isoforme p33 est indépendante de la formation de ces vésicules. La trimérisation d’Ii représente la toute première étape dans la formation des complexes Ii-CMHII. Deux domaines d’Ii permettent la formation de trimères; le domaine de trimérisation (TRIM) et le domaine transmembranaire (TM). Nous nous sommes intéressés à la nécessité de ces domaines dans la trimérisation de la chaîne et la formation subséquente de complexes avec les CMHII. Nous avons démontré que le domaine TRIM n’est pas essentiel à la trimérisation de la chaîne, à la formation de pentamères et de nonamères ainsi qu’au trafic adéquat de ces complexes Ii-CMHII dans la cellule. En absence des domaines TM d’Ii et des CMHII, nous avons observé la formation de complexes pseudo-nonamériques. Ceci suppose que la présence de ce domaine n’est pas un prérequis à la formation de nonamères. En conséquence, la présence d’un seul domaine de trimérisation de Ii est requise pour la formation de trimères et de complexes nonamériques. L’ensemble de nos résultats démontrent que la fonction de p35 n’est pas redondante à celle de p33. p35 influence de manière distincte le trafic des CMHII puisqu’il affecte la stœchiométrie des sous-unités incorporées aux complexes Ii- CMHII. / The invariant chain (Ii) assists in the folding and trafficking of MHC class II molecules (MHCII). Four different isoforms of the human Ii have been described (p33, p35, p41 and p43). The main isoforms, p33 and p35, differ by the presence of a di-arginine (RXR) endoplasmic reticulum (ER) retention motif in p35. This motif is inactivated upon binding of MHCII. In the ER, p33 and p35 assemble into trimers before associating with MHCII. The sequential binding of up to three MHCII αß dimers to Ii trimers results in the formation of pentamers, heptamers and nonamers. However, the exact stoichiometry of the Ii-MHCII complex and the mechanism allowing shielding of the ER retention motif remain a matter of debate. To shed light on these issues, we chose a functional approach to examine the stoichiometry of complexes formed around the p33 and p35 isoforms. We showed that p35 promotes formation of nonameric complexes (αßIi)3 while formation of pentameric complexes (αß)1Ii3 was observed for p33. We then showed that formation of nonameric complexes can result in the inclusion of distinct MHCII isotypes around a single trimeric p35 scaffold. When answering the question wetter masking of the p35 RXR motif by MHCII results in the formation of nonamers, we showed that the actual inactivation of motif requires a direct cis-interaction between p35 and the MHCII, precluding ER egress of unsaturated p35 trimers. Interestingly, as opposed to p33-MHCII complexes, p35-MHCII complexes remained in the ER when co-expressed with the NleA protein of enterohaemorrhagic Escherichia coli. Expression of this bacterial protein is thought to interfere with the formation of COPII vesicles, leading to the conjecture that p35-MHCII and p33-MHCII complexes exit the ER in a COPII-dependant and COPII-independent manner, respectively. The trimerization of Ii represents the very first step in the formation of Ii-MHCII complex. Two domains of Ii, the trimerization domain (TRIM) and the transmembrane (TM) domain have been shown to trigger the trimerization of the chain. We focused our attention on the requirement of the two trimerization domains in Ii self-association and in the formation of pentameric and nonameric complexes. We showed that the TRIM domain of Ii is not essential for the chain’s trimerization, formation of pentamers and nonamers and for proper traffic with MHCII molecules. In absence of the Ii and MHCII TM domains, we observed the formation of a nonamer-like structure hereby suggesting that the presence of this domain is not a prerequisite for nomamer complex formation. Consequently, our results showed that either Ii trimerization domains are sufficient for Ii trimer formation and nonameric complex trafficking. Taken together, our results demonstrate that the function of the p35 isoform is not redundant, influencing distinctively MHCII trafficking as the subunit stoichiometry of oligomeric Ii/MHCII complexes is affected by p35.

A busca por uma construção vacinal contra o HIV-1 é urgente. Os linfócitos T CD4+ têm assumido um papel de destaque no campo de vacinas por participar no controle da replicação do HIV-1, seja auxiliando as funções efetoras de linfócitos T CD8+ e a produção de anticorpos por linfócitos B ou mesmo agindo de forma citotóxica sobre macrófagos infectados. A utilização de sequências consenso do grupo M do HIV-1 é apontada como uma das maneiras de se contornar os problemas relacionados à diversidade viral. Além disso, é preciso construir vacinas que apresentem potencial de induzir respostas imunes com grande cobertura populacional. Com o intuito de induzir respostas amplas de linfócitos T CD4+ contra diversos subtipos do HIV-1 em uma população geneticamente diversa para moléculas HLA-DR, identificamos em nosso trabalho prévio 34 peptídeos promíscuos (previstos de se ligarem a múltiplas moléculas HLA-DR) e conservados da sequência consenso do grupo M do HIV-1. Desenvolvemos uma vacina de DNA codificando 7 peptídeos de Env (HIVenv7) e outra vacina (HIVBr27) codificando os demais 27 peptídeos. A vacina HIVBr27 foi imunogênica em camundongos BALB/c, induzindo uma resposta ampla e polifuncional de linfócitos T CD4+ e CD8+. A vacina HIVenv7 foi pouco imunogênica e mostrou-se capaz de suprimir a resposta induzida pela HIVBr27 em regime de co-imunização. No presente trabalho demonstramos que a imunização com HIVBr27 induz uma resposta imune celular mediada por linfócitos T CD4+ e CD8+ contra peptídeos de diferentes subtipos do HIV-1. Além disso, a imunização com HIVBr27 mostrou-se parcialmente protetora contra a infecção pelo vírus Vaccinia recombinante codificando as proteínas Gag e Pol do HIV-1. Ensaios in vitro demonstraram que os peptídeos codificados pela HIVBr27 se ligam a múltiplas moléculas HLA de classe II e são reconhecidos por células de pacientes infectados pelo HIV-1. Demonstramos também que a vacina HIVenv7 não possui propriedades imunossupressoras consistentes, contrariando os resultados obtidos previamente. Os peptídeos codificados pela HIVenv7 se ligaram a múltiplas moléculas HLA de classe II, mas apresentaram baixa frequência de reconhecimento por células de pacientes infectados pelo HIV-1. Acreditamos que a vacina HIVBr27 possui potencial de induzir uma resposta imune de grande cobertura populacional e direcionada a diferentes variantes do HIV-1. Por outro lado, a vacina HIVenv7 se mostrou pouco imunogênica e não deve ser utilizada em estudos futuros / The search for an HIV-1 vaccine construct is urgent. The CD4+ T cells have assumed a prominent role in the vaccine field participating in the control of HIV-1 replication either by helping CD8+ T cell effector function and B cell-mediated antibody production or by acting as citotoxic cells on infected macrophages. The use of HIV-1 M-group consensus sequences is pointed as an alternative to overcome viral diversity. Besides, it is necessary to construct vaccines that would potentially induce immune responses with broad population coverage. Intending to induce a broad CD4+ T-cell immune response against different HIV-1 subtypes in a population bearing diverse HLA-DR molecules we have previously identified 34 promiscuous peptides (potentially binding to multiple HLA-DR molecules) and conserved within the HIV-1 M-group consensus sequence. We construct a DNA vaccine encoding 7 Env peptides (HIVenv7) and another vaccine (HIVBr27) encoding 27 peptides. The HIVBr27 vaccine was immunogenic in BALB/c mice, inducing a broad and polyfunctional CD4+ and CD8+ T-cell response. The HIVenv7 vaccine was much less immunogenic and suppressed HIVBr27-induced immune responses when co-immunized. Here, we have shown that HIVBr27 immunization leads to a cross-clade CD4+ and CD8+ T-cell immune response. Besides, HIVBr27 immunization has partially protected mice challenged with a recombinant Vaccinia virus encoding HIV-1 Gag e Pol. In vitro assays have shown that HIVBr27- encoded peptides bind to multiple HLA class II molecules and are recognized by HIV- 1-infected patients. We have also shown that HIVenv7 has no consistent immunosuppressive properties, contradicting our previous results. The HIVenv7- encoded peptides bound to multiple HLA class II molecules but were recognized by a low number of HIV-1-infected patients. We believe that our vaccine HIVBr27 has potential to induce an immune response with broad population coverage, towards different HIV-1 variants. On the other hand, the HIVenv7 vaccine was poorly immunogenic and should not be used in future studies

INTRODUÇÃO: O Pênfigo Vulgar é uma doença bolhosa crônica que acomente pele e mucosas. A perda de adesão epitelial ocorre por agressão autoimune às desmogleínas presentes nos desmossomos, mediada por anticorpos IgG. Estudos sobre a gênese da autoimunidade no pênfigo indicam associação entre alelos do sistema HLA, especialmente dos loci DR e DQ. A população brasileira apresenta características favoráveis a estudos exploratórios em genética decorrente de sua origem mista e intensa miscigenação. PACIENTES E MÉTODO: O grupo em estudo incluiu trinta e seis pacientes não consanguíneos com diagnóstico de Pênfigo Vulgar comprovado por imunopatologia provenientes do estado de São Paulo, Brasil. Foram tipados para os loci HLA-A, HLA-B e HLA-DR utilizando-se oligonucleotídeos sequência-específica (PCR-SSO). As frequências alélicas e fenotípicas encontradas foram comparadas com as de um grupo controle composto de dados de 712 indivíduos doadores voluntários cadastrados no Registro Nacional de Doadores de Medula Óssea (REDOME) provenientes de São Paulo e tipados pelo mesmo método. O valor de P crítico foi corrigido utilizando-se o método False Discovery Rate. RESULTADOS: Os alelos HLA-DRB1*04:02, DRB1*08:04 e DRB1*14 estiveram associados à doença com riscos relativos de 44,6, 18,6 e 4,8, respectivamente (p<0,001). Não houve diferença estatisticamente significante entre as frequências de nenhum alelo dos loci HLA-A ou HLA-B entre os grupos. DISCUSSÃO: O alelo DRB1*04:02, diretamente, e o alelo DRB1*14, indiretamente por desequilíbrio de ligação com DQB1*05:03, estão associados com Pênfigo Vulgar em diversas populações ao redor do mundo, porém nenhum estudo semelhante observou associação com o alelo DRB1*08:04 em tamanha magnitude. Acreditamos que as associações encontradas em nosso estudo não sejam decorrentes de viés de estratificação populacional. É necessária, no entanto, a tipagem de loci adjascentes ao HLA-DR dos indivíduos do grupo em estudo para diferenciar se o risco à doença é inerente a estes alelos ou a algum outro nas proximidades, com o qual estariam em desequilíbrio de ligação. CONCLUSÕES: Os alelos HLA-DRB1*04:02, DRB1*08:04 e DRB1*14 estiveram associados ao Pênfigo Vulgar em pacientes brasileiros. / BACKGROUND: Pemphigus vulgaris is a chronic blistering disease affecting skin and mucous membranes. Autoimmune aggression to desmoglein in desmosomes, mediated by IgG antibodies, leads to loss of epithelial cell adhesion. Studies indicate association between some alleles of the HLA system and pemphigus vulgaris, mainly at the DR and DQ loci. Brazilian population characteristics are conducive to genetic exploratory studies because of its various origins and intense ethnically admixture. PATIENTS AND METHODS: The study group consisted of thirty-six unrelated patients with clinical and immunopathological diagnosis of pemphigus vulgaris from a tertiary hospital in Sao Paulo - Brazil. HLA allele typing at the A, B and DR loci was performed after DNA extraction using polymerase chain reaction and sequence-specific oligonucleotide probes (PCR-SSO). Allele and phenotypic frequencies were compared to those from a control group composed by 712 individuals volunteer donors registered in a national registry of bone marrow donors (REDOME) from Sao Paulo, typed using the same method. False Discovery Rate method was used to adjust level of critical P values. RESULTS: The HLADRB1* 04:02, DRB1*08:04 and DRB1*14 were associated with pemphigus vulgaris with relative risks of 44.6, 18.6 and 4.8, respectively (p <0.001). There was no significant difference between the frequencies of any allele of loci HLAA or HLA-B among the groups. DISCUSSION: The alleles DRB1*04:02 and DRB1*14 (indirectly through linkage disequilibrium with the DQB1*05:03) are associated with pemphigus vulgaris in several populations worldwide, however, no similar study reported such magnitude of association between pemphigus vulgaris and DRB1*08:04 allele. We consider that the association is not secondary to population stratification bias. HLA typing of nearby loci is required to differentiate if the association with pemphigus vulgaris is inherent to the HLA-DRB1*08:04 allele or to another gene which is in linkage disequilibrium. CONCLUSIONS: The HLA-DRB1*04:02, DRB1*08:04 and DRB1*14 were associated with pemphigus vulgaris in Brazilian patients

INTRODUÇÃO: Pênfigo Vulgar é uma doença bolhosa mucocutânea autoimune caracterizada pela formação de bolhas ou ulcerações dolorosas que afetam as superfícies cutâneas e/ou mucosas. A perda do contato célulacélula entre os queratinócitos do epitélio (acantólise) resulta na manifestação clínica do Pênfigo Vulgar. Autoanticorpos IgG se ligam às desmogleínas - anti-desmogleína 3 (Dsg3) e/ou anti-desmogleína 1 (Dsg1) -e são críticos na patogênese da doença. A predisposição genética ao PV, principalmente com alelos HLA DR e DQ, foi revelada desde a década de 80 e foi comprovada por análises genéticas e sorológicas, repetidas vezes. As características singulares da população brasileira favorecem estudos genéticos exploratórios. PACIENTES E MÉTODO: O grupo em estudo incluiu 51 pacientes com diagnóstico confirmado de Pênfigo Vulgar de um hospital terciário da cidade de São Paulo, estado de São Paulo, sudeste do Brasil. Foi realizada a extração de DNA e a tipificação de HLA A, B, C, DR e DQ por meio de kits QIagen (QIAamp DNA Mini Kit®). O grupo controle foi composto a partir de um banco de dados de 297 doadores falecidos não relacionados da cidade de São Paulo, que foram tipados pelo mesmo método. Este banco faz parte do Sistema Estadual de Transplantes da Secretaria de Saúde do Governo do Estado de São Paulo e contém a idade do paciente na coleta. O nível de significância dos testes estatísticos foi ajustado pela correção de Bonferroni, dependendo da quantidade de frequências fenotípicas avaliadas para o HLA A, HLA B, HLA C, HLA DRB1 e HLA DQB1. RESULTADOS: Os alelos HLAB* 57, HLA-C*15, HLA-DRB1*04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 e o DQB1*05:03 estiveram associados com a susceptibilidade. Ambos os alelos HLA DRB1*04:02 e HLA-DRB1*14:01 e seus respectivos haplótipos DRB1*04-DQA1*03:01-DQB1*03:02 e DRB1*14- DQA1*01:01-DQB1*05:03 conferiram risco à doença. DISCUSSÃO: Os alelos DRB1*04:02 e DQB1*05:03 estão associados com o Pênfigo Vulgar no presente estudo, bem como a diversas populações do mundo. A associação aqui estudada com o DRB1*08:04 foi confirmada por causa deste alelo específico e não do desequilíbrio de ligação a algum gene adjacente. A associação do alelo HLA-B*57 ao pênfigo vulgar é reportada pela primeira vez pelo presente estudo. CONCLUSÕES: Os alelos HLA-B*57, HLA-C*15, HLADRB1* 04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 e DQB1*05:03 estão associados ao Pênfigo Vulgar em pacientes brasileiros / BACKGROUND: Pemphigus vulgaris is a mucocutaneous blistering autoimune disease that manifests as painful blisters or ulcerations on the skin and/or mucosal surfaces. The loss of cell-cell adhesion among the epithelial keratinocytes (acantholisis) leads to pemphigus vulgaris clinical findings. IgG autoantibodies target desmoglein - anti-Desmoglein 3 (Dsg3) and/or 1 (Dsg1) - play a major role in the disease pathogenesis. Genetic predisposal to pemphigus vulgaris, especially the HLA DR and DQ alleles, was revealed since the 80s and has been proven through genetic and serologic analysis repeatedly. The unique constitution of the Brazilian population favours genetics exploratory studies. PATIENTS AND METHODS: The study group included fifty-one patients with confirmed diagnosis of Pemphigus Vulgaris from a tertiary hospital in Sao Paulo\'s city and state, southeast Brazil. DNA extraction and HLA A, B, C, DR and DQ typing using Qiagen kits (QIAamp DNA Mini Kit®). The control group was composed by a database of 297 unrelated deceased donors from the city of São Paulo that were typed through the same method. This database is a part of the Transplants State System of the Government\'s Health Secretary from the State of Sao Paulo. The statistical significance level was adjusted by using the Bonferroni correction depending on the phenotypic frequencies evaluated to HLA A, HLA B, HLA C, HLA DRB1 e HLA DQB1. RESULTS: The alleles HLA-B*57, HLA-C*15, HLADRB1* 04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 and DQB1*05:03 were associated with susceptibility. Both alleles HLA DRB1*04:02 and HLA-DRB1*14:01 and their respective haplotypes DRB1*04-DQA1*03:01-DQB1*03:02 and DRB1*14-DQA1*01:01-DQB1*05:03 conferred risk to the disease. DISCUSSION: The DRB1*04:02 and DQB1*05:03 alleles are associated with Pemphigus Vulgaris in our study, as well in various populations. The association in our study with HLA-DRB1*08:04 was confirmed to be specific to this allele and not to linkage disequilibrium to any adjacent gene. The association between HLA-B*57 and pemphigus vulgaris is being reported for the first time at the present study. CONCLUSIONS: The alleles HLA-B*57, HLA-C*15, HLA-DRB1*04:02, HLADRB1* 08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 and DQB1*05:03 were associated with Pemphigus Vulgaris in Brazilian patients

A presença de uma inflamação crônica no músculo, a associação com outras doenças e a presença de auto-anticorpos, sugere o envolvimento de um mecanismo autoimune na patogênese da DMJ. Trinta e sete fragmentos musculares de pacientes com o diagnóstico de DMJ foram estudados com o objetivo de avaliar a expressão de MHC classes I e II, C5b-9 e fenotipagem das células inflamatórias CD4, CD8, CD20 e CD68 em tecido muscular e correlacionar com os principais parâmetros clínicos, laboratoriais, histológicos e terapêuticos desta doença. Os achados foram comparados à expressão em oito fragmentos musculares de pacientes com polimiosite (PM), cinco de dermatomiosite (DM) e quatro de distrofia. As expressões de MHC-I, MHC-II e C5b-9 foram identificadas por imunohistoquímica, através da técnica de imunoperoxidase StreptABComplex/HRP; as células CD20 e CD68, pelo sistema LSAB+ e CD4 e CD8, pela técnica EnVision-AP. A expressão de MHC-I apresentou positividade em 97,2% dos casos, enquanto que a expressão de MHC-II foi observada em apenas 21,6% dos casos. C5b-9 (83,8% de positividade), correlacionou-se com a presença de calcinose e envolvimento cardíaco. A presença de linfócitos CD4 (81,1% de positividade), CD8 (86,5% de positividade) e CD20 (62,2 % de positividade), e CD68 (97,2% de positividade) correlacionaram-se com o grau de inflamação observada na histologia muscular. A presença de CD4 e CD68, e marcação de C5b-9 também se correlacionaram com a intensidade de fraqueza muscular, e laboratorialmente, CD4 correlacionou-se com níveis elevados de CK e CD20 com DHL. Na DMJ observou-se maior expressão de C5b-9, CD4 e CD8 e menor expressão de MHC-I e II em comparação à DM e PM. A expressão destes marcadores foi sempre menor na distrofia. A expressão de MHC-I, adjuvante ao envolvimento dos linfócitos CD4 e CD8, sugere um mecanismo inicial celular citotóxico relacionado a maior gravidade do envolvimento muscular. A concomitância da maior expressão de C5b-9 foi um fator preditivo de comprometimento sistêmico e demanda de terapêutica imunossupresssora. Os resultados deste estudo apontam para o papel do MHC-I e II, C5b-9, CD4, CD8, CD20 e CD68 na patogênese da DMJ / The presence of chronic muscle inflammation, in association with other diseases and seric autoantibodies in JDM patients, suggest the involvement of an autoimmune mechanism in the pathogenesis of this inflammatory myopathy. Thirty seven muscle biopsy specimens from patients with JDM were analyzed in order to assess the expression of MHC-I and II, C5b-9, CD4, CD8, CD20 and CD68 and to correlate with the clinical, laboratorial, histological and therapeutical parameters. These findings were compared to the expression in five dermatomyositis (DM), eight polymyositis (PM) and four dystrophy cases. Immunohistochemical reactions for MHC-I and II and C5b-9 (StreptABCcomplex/HRP), CD4, CD8 (EnVision-AP) and CD20, CD68 (LSAB+) were evaluated. MHC-I expression was positive in 97.2% of the cases, whilst MHC-II was positive in only 21.6% of the cases. C5b-9 expression (positivity of 83.8%) correlated with calcinosis and cardiac involvement. The presence of lymphocytes CD4 (positivity of 81.1%), CD8 (positivity of 86.5%), CD20 (positivity of 62.2%), and CD68 (positivity of 97.2%) correlated with inflammation in muscular histology. The presence of CD4 and CD8 and expression of C5b-9 also correlated with the severity of muscle weakness, and CD4 expression correlated with serum levels of CK and CD20 with LDH. In JDM, the expressions of C5b-9, CD4 and CD8 were statistically more significant when compared to PM and DM, while expressions of MHC-I and II were lower in JDM. All expressions were lower in dystrophy. MHC-I expression, adjuvant to the presence of CD4 and CD8 lymphocytes, corroborates the involvement of the cytotoxic cellular mechanism of muscular lesion in JDM, which correlates to severity. Concomitantly, C5b-9 expression was a predictive factor of systemic involvement and of the need for imunossupressive treatment. The results of this study indicate for the function of MHC-I and II, C5b-9, CD4, CD8, CD20 e CD68 at JDM pathogenesis

INTRODUÇÃO: Pênfigo Vulgar é uma doença bolhosa mucocutânea autoimune caracterizada pela formação de bolhas ou ulcerações dolorosas que afetam as superfícies cutâneas e/ou mucosas. A perda do contato célulacélula entre os queratinócitos do epitélio (acantólise) resulta na manifestação clínica do Pênfigo Vulgar. Autoanticorpos IgG se ligam às desmogleínas - anti-desmogleína 3 (Dsg3) e/ou anti-desmogleína 1 (Dsg1) -e são críticos na patogênese da doença. A predisposição genética ao PV, principalmente com alelos HLA DR e DQ, foi revelada desde a década de 80 e foi comprovada por análises genéticas e sorológicas, repetidas vezes. As características singulares da população brasileira favorecem estudos genéticos exploratórios. PACIENTES E MÉTODO: O grupo em estudo incluiu 51 pacientes com diagnóstico confirmado de Pênfigo Vulgar de um hospital terciário da cidade de São Paulo, estado de São Paulo, sudeste do Brasil. Foi realizada a extração de DNA e a tipificação de HLA A, B, C, DR e DQ por meio de kits QIagen (QIAamp DNA Mini Kit®). O grupo controle foi composto a partir de um banco de dados de 297 doadores falecidos não relacionados da cidade de São Paulo, que foram tipados pelo mesmo método. Este banco faz parte do Sistema Estadual de Transplantes da Secretaria de Saúde do Governo do Estado de São Paulo e contém a idade do paciente na coleta. O nível de significância dos testes estatísticos foi ajustado pela correção de Bonferroni, dependendo da quantidade de frequências fenotípicas avaliadas para o HLA A, HLA B, HLA C, HLA DRB1 e HLA DQB1. RESULTADOS: Os alelos HLAB* 57, HLA-C*15, HLA-DRB1*04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 e o DQB1*05:03 estiveram associados com a susceptibilidade. Ambos os alelos HLA DRB1*04:02 e HLA-DRB1*14:01 e seus respectivos haplótipos DRB1*04-DQA1*03:01-DQB1*03:02 e DRB1*14- DQA1*01:01-DQB1*05:03 conferiram risco à doença. DISCUSSÃO: Os alelos DRB1*04:02 e DQB1*05:03 estão associados com o Pênfigo Vulgar no presente estudo, bem como a diversas populações do mundo. A associação aqui estudada com o DRB1*08:04 foi confirmada por causa deste alelo específico e não do desequilíbrio de ligação a algum gene adjacente. A associação do alelo HLA-B*57 ao pênfigo vulgar é reportada pela primeira vez pelo presente estudo. CONCLUSÕES: Os alelos HLA-B*57, HLA-C*15, HLADRB1* 04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 e DQB1*05:03 estão associados ao Pênfigo Vulgar em pacientes brasileiros / BACKGROUND: Pemphigus vulgaris is a mucocutaneous blistering autoimune disease that manifests as painful blisters or ulcerations on the skin and/or mucosal surfaces. The loss of cell-cell adhesion among the epithelial keratinocytes (acantholisis) leads to pemphigus vulgaris clinical findings. IgG autoantibodies target desmoglein - anti-Desmoglein 3 (Dsg3) and/or 1 (Dsg1) - play a major role in the disease pathogenesis. Genetic predisposal to pemphigus vulgaris, especially the HLA DR and DQ alleles, was revealed since the 80s and has been proven through genetic and serologic analysis repeatedly. The unique constitution of the Brazilian population favours genetics exploratory studies. PATIENTS AND METHODS: The study group included fifty-one patients with confirmed diagnosis of Pemphigus Vulgaris from a tertiary hospital in Sao Paulo\'s city and state, southeast Brazil. DNA extraction and HLA A, B, C, DR and DQ typing using Qiagen kits (QIAamp DNA Mini Kit®). The control group was composed by a database of 297 unrelated deceased donors from the city of São Paulo that were typed through the same method. This database is a part of the Transplants State System of the Government\'s Health Secretary from the State of Sao Paulo. The statistical significance level was adjusted by using the Bonferroni correction depending on the phenotypic frequencies evaluated to HLA A, HLA B, HLA C, HLA DRB1 e HLA DQB1. RESULTS: The alleles HLA-B*57, HLA-C*15, HLADRB1* 04:02, HLA-DRB1*08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 and DQB1*05:03 were associated with susceptibility. Both alleles HLA DRB1*04:02 and HLA-DRB1*14:01 and their respective haplotypes DRB1*04-DQA1*03:01-DQB1*03:02 and DRB1*14-DQA1*01:01-DQB1*05:03 conferred risk to the disease. DISCUSSION: The DRB1*04:02 and DQB1*05:03 alleles are associated with Pemphigus Vulgaris in our study, as well in various populations. The association in our study with HLA-DRB1*08:04 was confirmed to be specific to this allele and not to linkage disequilibrium to any adjacent gene. The association between HLA-B*57 and pemphigus vulgaris is being reported for the first time at the present study. CONCLUSIONS: The alleles HLA-B*57, HLA-C*15, HLA-DRB1*04:02, HLADRB1* 08:04, HLA-DRB1*14:01, DQA1*03:01, DQB1*03:02 and DQB1*05:03 were associated with Pemphigus Vulgaris in Brazilian patients

INTRODUÇÃO: O Pênfigo Vulgar é uma doença bolhosa crônica que acomente pele e mucosas. A perda de adesão epitelial ocorre por agressão autoimune às desmogleínas presentes nos desmossomos, mediada por anticorpos IgG. Estudos sobre a gênese da autoimunidade no pênfigo indicam associação entre alelos do sistema HLA, especialmente dos loci DR e DQ. A população brasileira apresenta características favoráveis a estudos exploratórios em genética decorrente de sua origem mista e intensa miscigenação. PACIENTES E MÉTODO: O grupo em estudo incluiu trinta e seis pacientes não consanguíneos com diagnóstico de Pênfigo Vulgar comprovado por imunopatologia provenientes do estado de São Paulo, Brasil. Foram tipados para os loci HLA-A, HLA-B e HLA-DR utilizando-se oligonucleotídeos sequência-específica (PCR-SSO). As frequências alélicas e fenotípicas encontradas foram comparadas com as de um grupo controle composto de dados de 712 indivíduos doadores voluntários cadastrados no Registro Nacional de Doadores de Medula Óssea (REDOME) provenientes de São Paulo e tipados pelo mesmo método. O valor de P crítico foi corrigido utilizando-se o método False Discovery Rate. RESULTADOS: Os alelos HLA-DRB1*04:02, DRB1*08:04 e DRB1*14 estiveram associados à doença com riscos relativos de 44,6, 18,6 e 4,8, respectivamente (p<0,001). Não houve diferença estatisticamente significante entre as frequências de nenhum alelo dos loci HLA-A ou HLA-B entre os grupos. DISCUSSÃO: O alelo DRB1*04:02, diretamente, e o alelo DRB1*14, indiretamente por desequilíbrio de ligação com DQB1*05:03, estão associados com Pênfigo Vulgar em diversas populações ao redor do mundo, porém nenhum estudo semelhante observou associação com o alelo DRB1*08:04 em tamanha magnitude. Acreditamos que as associações encontradas em nosso estudo não sejam decorrentes de viés de estratificação populacional. É necessária, no entanto, a tipagem de loci adjascentes ao HLA-DR dos indivíduos do grupo em estudo para diferenciar se o risco à doença é inerente a estes alelos ou a algum outro nas proximidades, com o qual estariam em desequilíbrio de ligação. CONCLUSÕES: Os alelos HLA-DRB1*04:02, DRB1*08:04 e DRB1*14 estiveram associados ao Pênfigo Vulgar em pacientes brasileiros. / BACKGROUND: Pemphigus vulgaris is a chronic blistering disease affecting skin and mucous membranes. Autoimmune aggression to desmoglein in desmosomes, mediated by IgG antibodies, leads to loss of epithelial cell adhesion. Studies indicate association between some alleles of the HLA system and pemphigus vulgaris, mainly at the DR and DQ loci. Brazilian population characteristics are conducive to genetic exploratory studies because of its various origins and intense ethnically admixture. PATIENTS AND METHODS: The study group consisted of thirty-six unrelated patients with clinical and immunopathological diagnosis of pemphigus vulgaris from a tertiary hospital in Sao Paulo - Brazil. HLA allele typing at the A, B and DR loci was performed after DNA extraction using polymerase chain reaction and sequence-specific oligonucleotide probes (PCR-SSO). Allele and phenotypic frequencies were compared to those from a control group composed by 712 individuals volunteer donors registered in a national registry of bone marrow donors (REDOME) from Sao Paulo, typed using the same method. False Discovery Rate method was used to adjust level of critical P values. RESULTS: The HLADRB1* 04:02, DRB1*08:04 and DRB1*14 were associated with pemphigus vulgaris with relative risks of 44.6, 18.6 and 4.8, respectively (p <0.001). There was no significant difference between the frequencies of any allele of loci HLAA or HLA-B among the groups. DISCUSSION: The alleles DRB1*04:02 and DRB1*14 (indirectly through linkage disequilibrium with the DQB1*05:03) are associated with pemphigus vulgaris in several populations worldwide, however, no similar study reported such magnitude of association between pemphigus vulgaris and DRB1*08:04 allele. We consider that the association is not secondary to population stratification bias. HLA typing of nearby loci is required to differentiate if the association with pemphigus vulgaris is inherent to the HLA-DRB1*08:04 allele or to another gene which is in linkage disequilibrium. CONCLUSIONS: The HLA-DRB1*04:02, DRB1*08:04 and DRB1*14 were associated with pemphigus vulgaris in Brazilian patients