RESUMO
Epigenetic deregulation of genes encoded on the X chromosome as reported for CD40L in lupus could explain the female predominance of autoimmune diseases. We compared CD40L expression on CD4(+) T cells from primary Sjögren's syndrome (pSS) women and healthy controls and investigated DNA methylation patterns of the promoter and enhancer regions of CD40L. The expression of CD40L on activated CD4(+) T cells was higher in patients with pSS than controls after phorbolmyristate acetate and ionomycin activation (P = 0.02). CD40L mRNA level in CD4(+) T cells did not differ between patients with pSS and controls and was similar in both groups in cultures treated with the demethylating agent 5-azacytidine C. Pyrosequencing analysis revealed no significant differences in methylation profiles between patients and controls. Inducible membrane-bound CD40L on CD4(+) T cells is increased in patients with pSS but was not related to epigenetic deregulation by demethylation patterns of the regulatory regions of CD40L.
Assuntos
Ligante de CD40/imunologia , Proteínas de Membrana/imunologia , Síndrome de Sjogren/imunologia , Regulação para Cima/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Azacitidina/farmacologia , Ligante de CD40/genética , Células Cultivadas , Metilação de DNA/efeitos dos fármacos , Metilação de DNA/imunologia , Feminino , Expressão Gênica/imunologia , Humanos , Ionomicina/farmacologia , Ativação Linfocitária/efeitos dos fármacos , Ativação Linfocitária/imunologia , Proteínas de Membrana/genética , Pessoa de Meia-Idade , Regiões Promotoras Genéticas/genética , Regiões Promotoras Genéticas/imunologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA/métodos , Síndrome de Sjogren/genética , Síndrome de Sjogren/patologia , Linfócitos T/imunologia , Linfócitos T/metabolismo , Acetato de Tetradecanoilforbol/análogos & derivados , Acetato de Tetradecanoilforbol/farmacologia , Adulto JovemRESUMO
Signal transducer and activator of transcription 4 (STAT4) is a transcription factor mainly activated by interleukin 12, which promotes the secretion of type 2 interferon (IFN) by T-helper 1 cells. We assessed the association of STAT4 gene polymorphism and primary Sjögren's syndrome (pSS) and its functional relevance. We analyzed STAT4 rs7582694 polymorphism in an exploratory cohort of 186 pSS patients and 152 controls, and in a replication cohort of 192 pSS patients and 483 controls, all Caucasian. mRNA levels of STAT4alpha, STAT4beta, STAT1, and the type 1 IFN-induced genes PKR, MX1 and IFITM1 were assessed in peripheral blood mononuclear cells (PBMCs) from 30 pSS patients. STAT4 rs7582694 C allele was associated with pSS in both cohorts (odds ratio (OR) 1.57, 95% confidence interval (CI) 1.27-1.93, P=2.3 x 10(-5)). The association was increased for homozygous subjects, which suggests a recessive effect of the STAT4 at-risk allele. STAT4alpha, STAT4beta and STAT1 mRNA levels in PBMCs were not significantly associated with rs7582694 genotypes, however the mRNA levels of STAT4alpha and type 1 IFN-induced genes were strongly correlated: PKR (P=4 x 10(-3), r=0.51), MX1 (P=2 x 10(-4), r=0.63) and IFITM1 (P=8 x 10(-3), r=0.47), suggesting that STAT4 might be involved in not only type 2 IFN production but also in type 1 IFN-mediated effects.
Assuntos
Predisposição Genética para Doença/genética , Fator de Transcrição STAT4/genética , Transdução de Sinais/genética , Síndrome de Sjogren/genética , Antígenos de Diferenciação , Estudos de Casos e Controles , Estudos de Coortes , Proteínas de Ligação ao GTP/metabolismo , Estudo de Associação Genômica Ampla , Humanos , Leucócitos Mononucleares/imunologia , Proteínas de Membrana/metabolismo , Proteínas de Resistência a Myxovirus , Razão de Chances , Polimorfismo de Nucleotídeo Único/genética , Transdução de Sinais/imunologia , eIF-2 Quinase/metabolismoRESUMO
LL37 exerts a dual pathogenic role in psoriasis. Bound to self-DNA/RNA, LL37 licenses autoreactivity by stimulating plasmacytoid dendritic cells-(pDCs)-Type I interferon (IFN-I) and acts as autoantigen for pathogenic Th17-cells. In systemic lupus erythematosus (SLE), LL37 also triggers IFN-I in pDCs and is target of pathogenic autoantibodies. However, whether LL37 activates T-cells in SLE and how the latter differ from psoriasis LL37-specific T-cells is unknown. Here we found that 45% SLE patients had circulating T-cells strongly responding to LL37, which correlate with anti-LL37 antibodies/disease activity. In contrast to psoriatic Th17-cells, these LL37-specific SLE T-cells displayed a T-follicular helper-(TFH)-like phenotype, with CXCR5/Bcl-6 and IL-21 expression, implicating a role in stimulation of pathogenic autoantibodies. Accordingly, SLE LL37-specific T-cells promoted B-cell secretion of pathogenic anti-LL37 antibodies in vitro. Importantly, we identified abundant citrullinated LL37 (cit-LL37) in SLE tissues (skin and kidney) and observed very pronounced reactivity of LL37-specific SLE T-cells to cit-LL37, compared to native-LL37, which was much more occasional in psoriasis. Thus, in SLE, we identified LL37-specific T-cells with a distinct functional specialization and antigenic specificity. This suggests that autoantigenic specificity is independent from the nature of the autoantigen, but rather relies on the disease-specific milieu driving T-cell subset polarization and autoantigen modifications.