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Ulcerative colitis and irritable bowel syndrome are multifactorial disorders with genetic predisposition. Recent studies suggest that the mucosal immune activation, increased intestinal permeability, and altered host-microbiota interactions may modulate innate immune response, thus contributing to immunopathogenesis of these diseases. Toll-like receptors (TLR) are considered to play the main role in genetic susceptibility to the conditions. The mechanisms for regulating activity of Toll-like receptors are represented by single-nucleotide gene polymorphisms (SNPs), thus producing allelotypes with different biological effects. Among all known TLRs, TLR2 is the most actively studied. The TLR2 gene is located on the long arm of the chromosome 4 and contains the genetic variant leading to the substitution of arginine for glutamine (Arg753Gln) in TLR2 protein. Meanwhile, the most studied SNP of TLR6 is located at the C745T position causing Pro249Ser amino acid substitution in the protein. The present work aimed for analysis of distribution of alleles, genotypes and haplotype combinations of the TLR2 and TLR6 SNPs, and their associations with predisposal for ulcerative colitis and irritable bowel syndrome in Russians from Chelyabinsk Region. The following methods were used in the study: isolation of DNA samples from whole blood, genotyping of the studied gene polymorphisms using PCR with electrophoretic detection. The frequencies of two-locus haplotypes formed by SNPs TLR2 TLR6 were calculated with Arlequin ver 3.5 software. Comparison of two populational samples for predisposition to UC and IBS was carried out using standard immunogenetic criteria. Significance of differences was set at p 0.05. Results: Analysis of the data showed the association of specific alleles and genotypes, but not TLR2 TLR6 haplotypes, with predisposition to the studied diseases. The Arg753Gln gene polymorphism of TLR2 was shown to be significant for a predisposition to ulcerative colitis, and SNP Pro249Ser TLR6 is associated with susceptibility to irritable bowel syndrome in Russians from the Chelyabinsk Region.

Rheumatoid arthritis (RA) is a multifactorial disease, with genetic component based on intergenic interactions leading to the formation of gene networks. The current trend in RA immunogenetic studies is to assess the gene-to-gene interactions. Among possible genetic factors contributing to RA development, the genes of main histocompatibility complex (HLA class II) play a fundamental role. TNFA gene is among possible candidate genes providing susceptibility to this disorder and contributing to its immune pathogenesis. The special location of this gene suggests arrangement of extended TNFA – HLA haplotypes. This work analyzed the distribution features of two-locus SNP haplotypes (TNFA and HLA DRB1) for their association with rheumatoid arthritis in Russians. The following methods were used: DNA isolation, PCR-based genotyping, RFLP analysis with electrophoretic detection. Calculation of two-locus haplotypes frequencies and linkage disequilibrium (D’; χ2; p) was carried out using the EM algorithm in the Arlequin ver 3.5 program. Comparison of paired samples was carried out using standard immunogenetic criteria. The significance level was 0.05. Analysis of the data showed that the two-locus haplotypes -1031T/C and -863C/A TNFA were not associated with predisposal for rheumatoid arthritis in Russian population sample. The haplotypes associated with predisposition for RA were TNFA -863*a – HLA DRB1*03, TNFA -1031*t – HLA DRB1*04, TNFA -1031*t – HLA DRB1*04. Meanwhile, TNFA -1031*t – HLA DRB1*15; TNFA -1031*t -HLA DRB1*11 proved to be protective haplotypes. Our study showed that, in addition to individual HLA II alleles, the predisposal or resistance to rheumatoid arthritis may be promoted by haplotypes of rare SNPs at positions -1031, -863 C/A of TNFA gene, and HLA DRB1.

Interleukin 17 plays a key role in the immunopathogenesis of rheumatoid arthritis (RA) and serves as a link between activation of innate and adaptive immune cells, whereas its increased expression may represent one of the causes for uncontrolled inflammation and formation of immunopathological reactions. Among members of the interleukin 17 family, most studied is IL-17A, which is characterized by peak biological activity. IL-17A is one of the important immune mediators able to induce production of other pro-inflammatory cytokines and chemokines and promote recruitment of inflammatory cells, such as monocytes and neutrophils, into inflamed organs. IL17A gene contains a number of polymorphic sites, wherein single-nucleotide substitutions particularly at position the -197G/A may affect its expression level. Here in case-control study we retrospectively examined contribution of genetic polymorphism at the -197G/A position within the IL17A gene. Allele-specific PCR was used to iderntify the -197G/A polymorphism in IL17A gene in groups of patients with rheumatoid arthritis and healthy donors of the Russian ethnic group. Our study was made within a framework on assessing immunogenetic component for rheumatoid arthritis in ethnic Russian subjects in the Chelyabinsk Region. Prevalence of IL17A gene alleles and genotypes obtained in the work is in agreement with the Hardy– Weinberg equilibrium, and is characterized by rather high frequency of allele replacement (40%), which is typical for Caucasoid populations. Thus, it was found that interpopulation differences are characteristic of such gene polymorphism shown not to be associated with predisposition to rheumatoid arthritis in ethnic Russian subjects in the Chelyabinsk Region. Women with RA in our study were found to display certain changfes in frequencies of alleles and genotypes formed due to single-nucleotide substitution in IL17A gene at position -197G/A. However, in women such features cannot be considered as additional risk factors for developing RA. Allele -197*G, homozygous genotype -197G/G may be considered as markers of late-onset for the first RA attack in women. Analysis on distribution of SNP -197G/A alleles and genotypes within the IL17A gene showed that such polymorphism is of low value predictor likely being more associated with some RA clinical variants, but not with predisposition to RA development.

A total of 112 Nagaybaks, a Turkic ethnoconfessional group living mainly in the Nagaybak district of the Chelyabinsk Region of Russian South Urals, were genotyped for HLA-A, -B, -DRB1, -DQA1 and -DQB1 loci using PCR-SSP (low-resolution) and HLA-A29 (high-resolution). All loci were in Hardy-Weinberg equilibrium (all p values >0.1 thus showing no locus-level deviations. The genotype data are available in the Allele Frequencies Net Database under the population name ''Russia, South Ural, Chelyabinsk Region, Nagaybaks" and the identifier AFND0003397.