Promoter polymorphisms in the IRF3 gene confer protection against systemic lupus erythematosus.

In order to identify a novel candidate gene in systemic lupus erythematosus (SLE), we analysed a panel of six genes encoding molecules involved in the type I interferon (IFN) system. We first identified variants in the five genes related to type I IFN pathway by sequencing. Genotyping of a panel of eight selected single-nucleotide polymorphisms (SNPs) in six candidate genes (TLR9, MYD88, IRF3, IRF7, IFNB1, IFNA17) was performed in 137 patients with SLE and matched with 152 healthy controls using polymerase chain reaction-restriction fragment length polymorphism analysis. In functional assay, quantitative real-time polymerase chain reaction was performed to assess constitutive IRF3 mRNA expression in peripheral blood mononuclear cells from healthy subjects with different IRF3 promoter haplotypes. Among eight SNPs genotyped, an IRF3 SNP at -925 was found to be associated with SLE after correction for multiple tests (corrected P=0.016). Of total five IRF3 SNPs genotyped, the promoter IRF3 SNPs -925A/G and -776C/T showed the most significant association with SLE. With regard to -925A/G, the frequency of GG genotype was significantly decreased among SLE patients compared with the control group (1.5% vs. 9.9%; chi(2)=10.0, P=0.0015, odds ratio 0.12, 95% confidence interval 0.027-0.554). Our experimental data indicated that constitutive IRF3 mRNA expression was significantly lower in cells carrying the minor G-T/G-T haplotype pair compared with those carrying the major A-C haplotype. In conclusion, we showed that the promoter SNPs of the IRF3 gene were significantly associated with resistance against SLE.

Amelioration of human lupus-like phenotypes in MRL/lpr mice by overexpression of interleukin 27 receptor alpha (WSX-1).

OBJECTIVE: In the present work, we investigate the role of interleukin (IL)27/IL27 receptor alpha (Ralpha) (WSX-1) in the development of autoimmune disorders in the MRL/lpr mouse, which is considered as an experimental model of systemic lupus erythaematosus (SLE) in humans. METHODS: We generated two strains of WSX-1 transgenic mice in the MRL/lpr background with different expression levels of WSX-1, and investigated the effect of WSX-1 overexpression on survival, glomerulonephritis and immunological properties. RESULTS: In comparison with wild type (WT) MRL/lpr and transgenic (Tg) low (TgL) mice, Tg high (TgH) mice exhibited a prolonged lifespan and no apparent development of autoimmune nephritis. Production of anti-dsDNA antibody and total IgG and IgG2a were significantly lower in TgH mice than those of TgL and WT mice. The expressed amounts of interferon (IFN)gamma and IL4 mRNA by CD4+ T cells from Tg mice decreased in a dose-dependent fashion. CD4+ splenic lymphocytes in TgH mice were more subject to the IL27-mediated suppression of cytokine production. In vitro stimulation of CD4+ T cells by IL27 resulted in over phosphorylation of STAT3 in TgH cells than in WT cells. CONCLUSION: WSX-1 overexpression in the MRL/lpr background rendered the autoimmune prone mice protected from the development of autoimmune diseases. Our results suggest that IL27 signalling may be a therapeutic target against autoimmune diseases, including human SLE.

Absence of association between the MCP-1 gene polymorphism and histological phenotype of lupus nephritis.

Lupus nephritis presents two polar histological patterns, diffuse proliferative glomerulonephritis (DPGN) and membranous glomerulonephritis (MGN). In the kidney tissue of DPGN, numerous mononuclear cells were seen in the interstitium and glomeruli; on the other hand in MGN, infiltrating cells were less frequent. Monocyte chemoattractant protein-1 (MCP-1) is a potent chemoattractant for monocytes, T-cells, and natural killer cells. In this study we assessed the significance of the MCP-1 gene in determination of the histological phenotype in lupus nephritis. There was no association between the risk of DPGN and the MCP-1 gene genotype.