Association of Nod-like receptor protein-1 (rs2670660) and Toll-like receptor-4 (rs4986790) with non-segmental vitiligo: A case-control study in South Indian population.

Non-segmental vitiligo (NSV) is an autoimmune skin disease. Genetics plays a predominant part in disease pathogenesis. Nucleotide-binding and oligomerization domain (NOD)-like receptors and pyrin-containing protein (NLRP) and Toll-like receptors (TLR) are pattern recognition receptors in mediating innate immunity. They participate in presenting pathogens and mediating the immune responses. NLRP and TLRs are involved in mediating immune response in various dermatological diseases. Understanding the influence of genetic polymorphisms of NLRP and TLRs associated with immune homeostasis might help us to understand the complex etiopathogenesis of NSV. Thus, we aimed to study the association of NLRP-1 (rs2670660) and TLR-4 (rs4986790) and the synergistic effects on disease spectrum, disease activity of NSV in South Indian population. This research was designed as a case-control genetic study with 264 patients and 264 controls. Genotyping of NLRP-1 (rs2670660) and TLR-4 (rs4986790) was performed by Taqman 5' allele discrimination assay and ARMS-PCR. Plasma levels of proteins were measured by enzyme-linked immunosorbent assay (ELISA). A statistically significant difference was observed with the frequency of homozygous GG genotype of NLRP-1 (rs2670660) (17.8% in cases vs. 5.3% in controls) (p < 0.0001; OR-3.73; 95% CI-1.94-7.14). Allele G was significantly frequent in 38% of the cases than in controls with 30% (p = 0.004; OR-1.46; 95% CI-1.13-1.89). Plasma NLRP-1 level was significantly higher in patients compared to controls (p < 0.05). Amongst cases, the plasma NLRP-1 levels did not show any difference with respect to their genotypes (p > 0.05). In TLR-4 (rs4986790), no significant difference in the frequency of genotypes and allele between cases and controls (p = 0.80) was observed; nevertheless, plasma TLR-4 was analogous between cases and controls (p > 0.05). Influence of genotype on plasma TLR-4 showed no significant difference in TLR-4 levels between GG and ancestral genotype AA, whilst heterozygous AG genotype showed a significant increase of TLR-4 compared to AA and GG (p = 0.02) amongst NSV cases. The obtained results suggest that NLRP-1 (rs2670660), and not TLR-4 ((rs4986790), is associated with increased risk of NSV in South Indian population.