| Summary: | Orientadora : Profa. Dra. Shirley Ramos da Rosa Utiyama === Coorientadora : Profa. Dra. Iara Taborda de Messias-Reason === Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências da Saúde, Programa de Pós-Graduação em Ciências Farmacêuticas. Defesa: Curitiba, 30/09/2014 === Inclui referências === Área de concentração: Análises Clínicas === Resumo: A artrite reumatoide (AR) e uma doenca autoimune inflamatoria cronica, com distribuicao familiar, fortemente associada ao aparecimento precoce de autoanticorpos, cuja concomitancia se relaciona a um pior prognostico da doenca. A via alternativa (VA) do sistema complemento tem importante participacao no processo inflamatorio da AR e o fator B (BF) constitui a proteina central de ativacao dessa via. Neste estudo, investigou-se a variabilidade alotipica de BF em pacientes com AR e familiares, visando associa-la com biomarcadores sorologicos e aspectos clinicos da doenca. Foram estudados 210 pacientes com AR (178 Š; 32 ‰; 18-84 anos) e 198 familiares (121 Š; 77 ‰; 7-91 anos). O grupo controle incluiu 98 individuos sadios (81 Š; 17 ‰; 23-81 anos) da mesma area geografica. Os alotipos de BF foram determinados por eletroforese em gel de agarose, sob alta voltagem e refrigeracao constante, seguida de imunofixacao com anticorpo anti-BF humano. Investigou-se a presenca dos autoanticorpos anti-peptideo ciclico citrulinado (anti-CCP), anti-vimentina mutada citrulinada (anti-MCV) e fator reumatoide IgA (FR-IgA) por ensaio imunoenzimatico (ELISA) e o FR-IgM por aglutinacao em latex. A positividade total dos anticorpos foi maior nos pacientes comparado a familiares e controles (p<0,0001). O anti-CCP foi o biomarcador mais comum nos pacientes (75,7%) e o FR-IgA nos familiares (14,6%), diferindo significativamente dos individuos sadios (5,4%; p=0,030; OR=2,98). A positividade concomitante para os quatro biomarcadores predominou entre os pacientes (46,2%; p<0,0001), enquanto nos familiares e controles predominou apenas um autoanticorpo (p<0,0001; p=0,016, respectivamente). Nao ocorreu associacao entre o numero de biomarcadores positivos e idade de diagnostico, classe funcional e tabagismo nos pacientes. A Sindrome de Sjogren secundaria (SS) foi mais frequente entre pacientes com tres biomarcadores positivos simultaneamente (p=0,018; OR=2,73), enquanto pacientes soronegativos apresentaram diminuicao de manifestacoes extra-articulares (MEA; p=0,017; OR=0,28). Nos familiares, a ocorrencia de artralgia esteve significativamente associada a positividade dos biomarcadores. A ausencia de associacao na distribuicao dos fenotipos e alotipos de BF entre pacientes/controles e familiares/controles mostrou que nao houve relacao entre as variantes alotipicas de BF e o desenvolvimento da doenca nos individuos em estudo, assim como nao houve relacao entre tais variantes e o genero dos pacientes, idade de inicio e classe funcional da AR. O fenotipo BF FS07 e alotipo BF*S07 associaram-se significativamente as MEA nos pacientes (p=0,0487; p=0,021; OR=6,62, respectivamente). Uma diminuicao significativa na positividade do anti-MCV nos pacientes com fenotipo BF F (p=0,021; OR=0,22), e aumento naqueles com alotipo BF*S (p=0,017; OR=3,77), caracterizou uma possivel relacao dessas variantes com a presenca do anti-MCV. A maior frequencia de FR-IgA nos familiares com BF FS07 (p=0,018; OR=7,78), e a associacao deste fenotipo e do alotipo BF*S07 com as MEA nos pacientes (p=0,021; OR=6,62), sugerem esta variante de BF como um marcador de mau prognostico na doenca e, aliado aos demais resultados, reforcam a importante participacao da VA na fisiopatogenia da AR.
Palavras chave: artrite reumatoide, via alternativa do complemento, fator B, autoanticorpos, doencas autoimunes. === Abstract: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease with familiar distribution and strong correlation with early development of autoantibodies, whose coexistence is associated with a worse prognosis. The alternative pathway of the complement system plays an important role in the inflammatory process of RA. Factor B (BF) is a protein that exerts a central role in the activation of this pathway. This study investigated the allotypic variability of BF in RA patients and relatives, aiming to associate it with serological biomarkers and clinical aspects of the disease. Serum samples of 210 patients with RA (178 Š; 32 ‰; 18-84 years) and 198 relatives (121 Š, 77 ‰, 7-91 years) were evaluated. The control group included 98 healthy individuals (81 Š, 17 ‰, 23-81 years) from the same geographic area. The BF allotypes were determined by high-voltage agarose gel electrophoresis, under constant cooling, followed by immunofixation with anti-human BF antibody. Anti-cyclic citrullinated peptide (anti-CCP), anti-mutated citrullinated vimentin (anti-MCV) and IgA-rheumatoid factor (RF) were determined by ELISA and IgM-RF by latex agglutination. Total positivity of antibodies was higher in patients compared to relatives and controls (p<0.0001). Anti-CCP was the most common biomarker in patients (75.7%) and RF-IgA the most common in relatives (14.6%) differing significantly from controls (5.4%, p=0.030, OR=2.98). Concomitant positivity for the four biomarkers was more common in patients (46.2%, p<0.0001), while most relatives and controls were positive for just one of them (p<0.0001; p=0.016, respectively). No association was observed between the number of positive biomarkers and age of disease onset, functional class and tobacco exposure in patients. Secondary Sjogren syndrome was more frequent in patients with 3 simultaneous positive biomarkers (p=0.018, OR=2.73), while seronegative patients presented less extra articular manifestations (EAM, p=0.017, OR=0.28). In relatives, the occurrence of arthralgia was significantly associated with positive biomarkers. There was no difference in the distribution of BF phenotypes and allotypes between patients and controls and relatives and controls, as well as in relation to gender, age of onset and functional class of RA. The increase of BF S (p=0.0391) in patients compared to relatives turned not significant after logistic regression correction. The BF FS07 phenotype and allotype BF*S07 were significantly associated with EAM in patients (p=0.0487, p=0.021, OR=6.62, respectively). A significant decrease in positivity of anti-MCV in patients BF F (p=0.021, OR=0.22), and increased in those with allotype BF*S (p=0.017, OR=3.77), characterized a possible relationship of these variants with anti-MCV. The highest frequency of RF-IgA in relatives BF FS07 (p=0.018, OR=7.78), and the association of this phenotype and allotype BF*S07 in patients with EAM (p=0.021; OR=6.62), suggests that this BF variant is a marker of poor prognosis in disease and, in addition with the other results, stresses the important role of the alternative pathway in RA pathogenesis.
Keywords: rheumatoid arthritis, alternative pathway of complement, factor B autoantibodies, autoimmune diseases.
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