Toll-like receptor 2 (TLR2) gene polymorphisms are not associated with sarcoidosis in the Japanese population

Abstract

Purpose: Sarcoidosis is a systemic inflammatory disease characterized by the formation of non-caseating granulomas, with varied clinical manifestations. The common etiology of sarcoidosis is uncertain, but it is thought to be triggered by an exogenous antigenic stimulus, such as some bacterial proteins. Toll-like receptors (TLRs) recognize microbial components and elicit innate as well as adaptive immune responses. It has been reported that polymorphisms in TLR2 might be important in a small group of Caucasian sarcoidosis patients. The present study aimed to establish whether these findings are relevant to the Japanese population.

Methods: We genotyped 5 single-nucleotide polymorphisms (SNPs) in TLR2 and assessed the allelic diversity between 257 Japanese sarcoidosis patients and 193 Japanese healthy controls.

Results: No significant differences in the frequency of TLR2 alleles and haplotypes in the sarcoidosis cases were found in comparison with the controls. However, marginal associations were observed for TLR2 at rs3804099 and rs3804100 in sarcoidosis patients with cutaneous manifestations.

Conclusions: Our results suggest that TLR2 polymorphisms are not significantly related to the pathogenesis of sarcoidosis in the Japanese population.

Figure 1

Linkage disequilibrium plot of five SNPs of TLR2 in sarcoidosis patients and healthy controls. The schematic of the TLR2 gene is shown as a black line, with boxes representing its three exons. The locations of the selected SNPs are indicated by the dotted lines. The Haplotype blocks were determined using the Haploview 4.2 software. Each box provides estimated statistics of the coefficient of determination, with brighter red representing a stronger Linkage disequilibrium. Values in squares represent pairwise D’ values.