ABSTRACT
OBJECTIVE: IL-10 is a pleiotropic cytokine involved in the regulation of innate and cell-mediated immunity and a key mediator within the disturbed SLE immune system. IL-10 binds to IL10R1, which is expressed on a variety of immune cells and activates the JAK-STAT pathway. Two (out of several known) genetic IL10R1 variants may alter IL-10 binding or signal transduction. Here we investigate the differential activity of these IL10R1 variants and their possible association with RA or SLE susceptibility. METHODS: IL10R1-wt, IL10R1-S138G, IL10R1-G330R, or IL10R1- S138G +G330R were cloned into pIRESpuro3 and transfected into HeLa cells. Single cell clones were tested for IL-10-induced SOCS3- and SLAM gene expression by real-time PCR. DNA from 182 RA patients, 222 SLE patients, and 250 healthy controls was genotyped by allele-specific PCR. RESULTS: A biphasic increase of SOCS3 mRNA was observed that peaked at 15 minutes and 4 hours after IL-10 stimulation. The presence of IL10R1 S138G and G330R showed a weaker induction of both SOCS3 and SLAM upon stimulation with IL-10. In RA a homozygous G330R genotype was more commonly present than in controls (15.4% vs. 7.6%; p<0.05). In SLE the G330R allele frequency was also increased (36.3% vs. 30.0%; p<0.05) without showing a gene-dose relationship at the genotype level. CONCLUSIONS: Based on these results, both variants of the IL10R1 gene are loss-of-function alleles. IL10R1 G330R may possibly contribute to RA or SLE disease susceptibility in Caucasian populations.
Subject(s)
Arthritis, Rheumatoid/genetics , Gene Silencing , Genetic Predisposition to Disease , Interleukin-10/genetics , Lupus Erythematosus, Systemic/genetics , Antigens, CD/genetics , Antigens, CD/metabolism , Arthritis, Rheumatoid/immunology , Clone Cells , Female , Gene Expression , HeLa Cells , Humans , Lupus Erythematosus, Systemic/immunology , Male , Middle Aged , Polymorphism, Single Nucleotide , Receptors, Cell Surface/genetics , Receptors, Cell Surface/metabolism , Signaling Lymphocytic Activation Molecule Family Member 1 , Suppressor of Cytokine Signaling 3 Protein , Suppressor of Cytokine Signaling Proteins/genetics , Suppressor of Cytokine Signaling Proteins/metabolism , TransfectionABSTRACT
Immune response to viral infection is an important determinant of liver injury in chronic hepatitis C (CHC). Experimental and clinical data suggest a protective role of interleukin-10 (IL-10) in hepatic fibrogenesis. The significance of two SNPs of the interleukin-10 receptor 1 (IL-10R1), S138G (SNP3) and G330R (SNP4) was investigated on (i) susceptibility to CHC, (ii) progression of hepatic fibrosis and (iii) response to interferon/ribavirin therapy. DNA and liver biopsies were obtained from 212 patients with HCV (hepatitis C virus)-genotype-1 infection. The allele frequencies were 0.17 for SNP3 and 0.33 for SNP4, both of which were indifferent from healthy controls (0.17 and 0.32, respectively). Stage 1 liver fibrosis was found in 22 cases (10.4%), stage 2 in 108 (50.9%), stage 3 in 27 (12.8%), and stage 4 (cirrhosis) in 55 (25.9%). An association was found between the SNP4 allele and the presence of cirrhosis (P=0.01). Homozygous SNP4 individual variants segregated within the cirrhosis group (P=0.03). We found neither an association with SNP3 nor with the necroinflammatory disease activity (as measured by ALT levels) nor with the response to antiviral therapy. Our work implies that IL-10R1 SNP4 is a recessively inherited risk factor for hepatic cirrhosis in HCV genotype-1 infection.
