Polymorphisms within the interleukin-10 receptor cDNA gene (IL10R) in Japanese patients with systemic lupus erythematosus

Role of interleukin-10 and interleukin-10 receptor in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by excessive production of a variety of autoantibodies, accumulation of immune complexes, and multiple organ systems involvement. Interleukin-10 (IL-10) has an important role in the growth, survival, differentiation, and function of B cells. Abnormally increased IL-10 synthesis seems contributing to the spontaneous hyperactivity of the B cell compartment, so that it can directly result in autoantibody production by committed plasma cells, circulating immune complexes formation, and eventually in tissue and organ damage, suggesting it might associate with the development of SLE. A better understanding of the regulation of IL-10 and its receptors (IL-10R) can likely provide more valuable clues to the pathogenic mechanisms underlying specific forms of SLE, so as to pave the way toward more effective therapeutics.

Missense polymorphisms within IL-10R1 exons are not associated with systemic lupus erythematosus in Chinese

OBJECTIVE

Studies have suggested that interleukin-10 receptor1 (IL-10R1) is involved in genetic susceptibility to systemic lupus erythematosus (SLE) in animal models and Caucasians. Therefore, the current study was designed to determine whether the IL-10R1 gene plays a role in the pathogenesis of human SLE in the Chinese Han population.

METHODS

The seven exons of the IL-10R1 gene were amplified and sequenced using a BigDye Terminator v1.1 Cycle Sequencing kit and an ABI 3100 DNA Analyzer. A missense single nucleotide polymorphism (SNP) locus with a minor allele frequency of at least 0.1 was chosen to evaluate the correlation with the incidence of SLE.

RESULTS

Seven SNPs were found to reside in the exons of the IL-10R1 gene. Among the SNPs, A744G was evaluated for a correlation with the incidence of SLE because A744G was the only missense SNP with a minor allele frequency of at least 0.1. There was no significant difference in the distribution of the A and G alleles between the SLE patient group and the healthy control group (P = 0.693). Furthermore, the genotype frequencies of A744A, A744G and G744G did not differ significantly between the two groups (P = 0.906).

CONCLUSION

In the Chinese Han population, missense SNPs within the exons of the IL-10R1 gene do not contribute to the development of SLE.

Correlation between some Th1 and Th2 cytokine receptor gene polymorphisms and systemic lupus erythematosus in Chinese patients

BACKGROUND

Genetic factors seem to play a significant role in the susceptibility to systemic lupus erythematosus (SLE). Some researchers have described amino acid polymorphisms within the interleukin-4 receptor (IL-4R) [isoleucine50valine (Ile50Val), arginine576glutamine (Arg576Gln), etc.], the IL-10R (G241A and G520A), and the interferon-gamma receptor (IFN-gammaR) [valine14methionine (Val14Met) and glutamine64arginine (Gln64Arg)].

METHODS

The Ile50Val genotypes were examined by the reverse transcription-polymerase chain reaction-single-strand conformation polymorphism (RT-PCR-SSCP) method and DNA sequencing. The RT-PCR-restriction fragment length polymorphism (RT-PCR-RFLP) method was used to detect the Arg576Gln, G241A, G520A, Val14Met, and Gln64Arg genotypes.

RESULTS

There were significant differences in the genotype frequencies of Ile50/Ile50, G520/G520, and G520/A520 between the SLE group and healthy control group. There was a positive correlation between the IL-4R Ile50/Ile50 genotype and the susceptibility to SLE (P = 0.022). This was also found for the IL-10R G520/G520 (P = 0.004) and G520/A520 (P = 0.055) genotypes. The risk of SLE susceptibility was increased in individuals with the genotype combinations Ile50/Ile50 and Gln576/Arg576 (P = 0.056) and G241/G241 and G520/G520 (P = 0.004). The IFN-gammaR2 Arg64/Arg64 genotype decreased the risk of SLE (P = 0.047). A decreased risk of development of SLE was detected in individuals with the genotype combination IFN-gammaR2 Arg64/Arg64 and IFN-gammaR1 Val14/Val14 (P = 0.004).

CONCLUSIONS

The IL-4R Ile50/Ile50 and IL-10R2 G520/G520 and G520/A520 genotypes were shown to determine the susceptibility to SLE in a Chinese population, as were the combinations Ile50/Ile50 and Gln576/Arg576, and G241/G241 and G520/G520.

Autoimmunity in systemic lupus erythematosus: integrating genes and biology

Susceptibility to the autoimmune phenotype of systemic lupus erythematosus (SLE) is heritable. Linkage analysis and recent advances in the field of single nucleotide polymorphisms (SNPs) have resulted in the identification of several genetic loci and functional allelic variants of signaling proteins which have become the mainstay of understanding disease susceptibility and exploring the basis of autoimmunity in SLE. However, genetic heterogeneity and possible epistatic interactions among genetic elements have precluded replication of these findings in multiple population groups and thus complicated their interpretation. In this regard, the discovery that a plethora of normal signaling proteins are expressed in abnormal amounts in immune cells from patients with SLE has gained significance. Thus, the key to precise elucidation of the pathologic basis of autoimmunity in SLE lies in tying genetics and disease biology. This review highlights recent discoveries of important functional genetic variants and altered expression of normal signaling proteins that network together to disrupt peripheral tolerance and initiate the autoimmune process in SLE.

Interleukin-10 therapy--review of a new approach

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Its main biological function seems to be the limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells such as T cells, B cells, natural killer cells, antigen-presenting cells, mast cells, and granulocytes. However, very recent data suggest IL-10 also mediates immunostimulatory properties that help to eliminate infectious and noninfectious particles with limited inflammation. Numerous investigations, including expression analyses in patients, in vitro and animal experiments suggest a major impact of IL-10 in inflammatory, malignant, and autoimmune diseases. So IL-10 overexpression was found in certain tumors as melanoma and several lymphomas and is considered to promote further tumor development. Systemic IL-10 release is a powerful tool of the central nervous system to prevent hyperinflammatory processes by activation of the neuro-endocrine axis following acute stress reactions. In contrast, a relative IL-10 deficiency has been observed and is regarded to be of pathophysiological relevance in certain inflammatory disorders characterized by a type 1 cytokine pattern such as psoriasis. Recombinant human IL-10 has been produced and is currently being tested in clinical trials. This includes rheumatoid arthritis, inflammatory bowel disease, psoriasis, organ transplantation, and chronic hepatitis C. The results are heterogeneous. They give new insight into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Novel variants of the IL-10 receptor 1 affect inhibition of monocyte TNF-alpha production

IL-10-deficient mice exhibit spontaneous enterocolitis and other symptoms akin to Crohn's disease, indicating that IL-10 might regulate normal physiology in the gut. However, clinical trials with IL-10 in Crohn's disease were disappointing, although some patients showed healing of intestinal mucosa. This study searched for genetic polymorphisms within the IL-10 pathway. We decided to screen for mutations of the IL-10R1 cDNA in healthy volunteers and Crohn's disease patients and identified two novel variants: a serine 138-to-glycine (S138G) and a glycine 330-to-arginine (G330R) substitution. The allelic frequency in a European cohort was relatively high (16% for the S138G and 33% for the G330R), and S138G was in strong linkage disequilibrium with G330R. A similar allele frequency was found in a group of Crohn's patients. In IL-10R1 G330R-expressing monocytes, the inhibitory effect of IL-10 on TNF-alpha production was diminished, indicating that this variant may be a loss-of-function allele. No such difference was observed between haplotypes 4 (G330R only) and 7 (S138G and G330R). In addition, these IL-10R1 variants had no influence on the IL-10R1 expression density. Structural analysis of the S138G variant revealed that the substitution of S138G may interfere with binding of IL-10 to IL-10R1.

Analysis of genetic polymorphisms at the interleukin-10 loci in aggressive and chronic periodontitis

BACKGROUND/AIMS

Different cytokine genotypes have been described in periodontal disease. The aim of the present study was to investigate the genetic association of two previously described interleukin-10 (IL-10) polymorphisms in patients with aggressive (AP) and chronic periodontitis (CP) and to investigate possible associations with clinical manifestations.

METHODS

Based on clinical parameters and radiographs, 23 patients with CP and 18 patients with AP were included in the study. Additionally, 21 age-matched healthy subjects served as a control group. Genomic DNA was isolated from whole blood samples and the IL-10 promoter sequences from positions - 597 to - 824 were amplified by polymerase chain reaction (PCR). Polymorphisms were detected by restriction-enzyme cleavage. The A and C alleles at the - 597 position were associated with the T and C alleles at the - 824 position, respectively. Fisher's exact test was used for the statistical analysis.

RESULTS

No significant differences were observed in the allele frequencies between controls and AP patients (p = 0.70) or CP patients (p = 0.43), although the previously reported association between allele A at position - 597 and allele T at position - 824 was observed in our population.

CONCLUSION

We conclude that the investigated polymorphisms are not associated with periodontal disease.

Cytokine polymorphisms in systemic lupus erythematosus and Sjögren's syndrome

Systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS) are defined genetically as complex diseases where multiple genes are involved in their pathogenesis. Among the genes of interest are those coding for the cytokines, molecules involved in immunoregulation that have been shown to play important roles in these diseases. Whether abnormalities in cytokine production are owing to genetic polymorphisms within the genes themselves is a matter of intensive study. The finding of functional polymorphisms within cytokine genes and their potential association with disease will open new avenues in their treatment.