C3 Gene Functional Polymorphisms and C3 Serum Levels in Patients with Rheumatoid Arthritis.

The complement system is a key component of the innate immunity that plays a significant role in the development and clinical presentation of Rheumatoid arthritis (RA). Complement protein C3 is a central molecule in the activation of complement with a significant role in the inflammatory processes of RA. Nevertheless, the impact of C3 gene polymorphisms in the development of RA is still unknown. The current study aimed to investigate the possible influence of C3 gene polymorphisms in the susceptibility and clinical expression of RA. Three C3 polymorphisms (rs2250656:A > G, intron 2; rs2230199:C > G [p.Arg102Gly], exon 3 and rs1047286:C > T [p.Pro314Leu], exon 9) were assessed by sequence-specific PCR in a total of 156 RA patients and 270 healthy controls from Southern Brazil. In addition, C3 levels were measured in 60 patients and 60 controls by immunoturbidimetry and clinical features were collected from medical records. The frequency of rs2230199 G allele and GG genotype was significantly higher in RA patients than controls (padj = 0.012 OR = 1.57 [1.11-2.31]; padj = 0.008, OR = 1.60 [1.35-2.33]) as well as the rs1047286 T and TT (padj = 0.010, OR = 1.67 [1.12-2.40]; padj = 0.001, OR = 1.83 [1.27-2.65] and the C3 AGT haplotype (padj = 0.0007 OR = 1.92 [1.32-2.80]). Moreover, C3 serum levels were higher in patients than controls (median: 169 mg/dl vs.155 mg/dl; padj = 0.022), as well as in RF seronegative compared with seropositive patients (172 mg/dl vs. 165 mg/dl; padj = 0.007). Our results suggest that the rs2230199 G (p.102Gly) and rs1047286 T (p.314Leu) alleles play a role in the pathophysiology of RA, possibly impacting complement activation by the alternative pathway.

Genetic Polymorphisms of Toll-like receptors 2 and 9 as Susceptibility Factors for the Development of Ankylosing Spondylitis and Psoriatic Arthritis.

INTRODUCTION: Ankylosing spondylitis (AS) and psoriatic arthritis (PsA) are classified as spondyloarthritis (SpA), a group of inflammatory rheumatic diseases with complex genetic etiology. Toll-like receptors (TLRs) have an important role in the mechanism of innate immunity and may influence inflammatory responses. Polymorphisms in TLR genes that lead to changes in these receptors or that interfere with the transcription rates of mRNA TLR may be involved in the chronic inflammatory immune response observed in SpA. Currently, there is a lack of studies associating genetic polymorphisms in TLRs and SpA. OBJECTIVE: Therefore, this case-control study is aimed at analyzing the influence of the respective SNPs on TLR2 rs5743708, TLR6 rs5743810, and TLR9 rs5743836 and rs187084 in the immunopathogenesis of SpA. METHODS: The polymorphisms genotyped by PCR-RFLP were TLR2 rs5743708, TLR6 rs5743810, and TLR9 rs5743836 and rs187084. The HLA-B ∗ 27 was performed by PCR-SSP. RESULTS: Logistic regression analysis showed a strong association between SNPs in TLR2 and TLR9 and susceptibility to SpA (OR = 12.56; CI = 6.5-25.9 and OR = 1.62; CI = 1.20-2.21, respectively). No association was observed among HLA-B ∗ 27 and TLR polymorphisms (p = 0.72), nor among BASDAI and TLR polymorphisms (p = 0.85). DISCUSSION: Our findings suggest that polymorphisms in TLR2 and TLR9 genes may contribute to the immunopathogenesis of the SpA. The rs187084, rs5743836, and rs5743708 polymorphisms were associated with the risk of SpA development, in this study, and lead to significant changes in the innate and adaptive immune response profile, as well as the maintenance of the regulation of immunological mechanisms. CONCLUSION: The polymorphism rs5743708 for the TLR2 and the rs187084_rs5743836 TLR9 haplotypes appear to be involved in the development of clinical forms of SpA and can be a possible therapeutic target for the spondyloarthritis.