TLR-2 Germ Line Variants as a Risk for Obesity in Local Pakistani Population

Background: Obesity is increasing rapidly affecting half billion adult's population. Pathophysiology of obesity involves low grade inflammation sustained by Toll like receptor 2 (TLR-2) the innate immune adapters. This study was conducted for detection and association of TLR-2 gene mutations with obesity.

Methods: In this case-control study 228 individuals with obesity and 228 controls were enrolled based on Body Mass Index (BMI) ≥25 and 18-24 kg/m² respectively. The variations in TLR-2 gene were detected by Sanger sequencing. These identified TLR-2 variants were further analyzed in silico for change in miRNA binding and mRNA strucutre.

Results: Four novel single base substitutions (153688371 T >C, 153702295 T >C, 153703504 T >C and 153705074 C >A) were identified in exon 3 and 4 of TLR-2 gene affecting splice site and poly-A tail. The genotypic and allelic frequencies of the variants were strongly associated with increasing obesity susceptibility. Only variant 153703504 T >C was significantly associated with preobesity. Despite variations in gene sequence, no change in miRNA binding except for variant 153688371 T >C of Exon 3 where a novel binding site for hsa-miR-4523 was created. Furthermore, mRNA stability and secondary structure were also compromised in identified variants.

Conclusion: All detected variants of TLR-2 gene were significantly associated with and posed risk for development of obesity. Furthermore, in silico analysis revealed generation of new miRNA (hsa-miR-4523) binding site and change in mRNA structure/stability which needs to be further investigated for possible role in altering TLR-2 gene regulation/expression in obesity.