Toll-Like Receptor (TLR)-9 rs352140 Polymorphism is an Immunopathology Protective Factor in Parkinson's Disease in the Northern Iranian Population

Neuroinflammation and immunopathology in Parkinson's disease (PD) are believed to be associated with genetic and environmental factors. We conducted the current study to evaluate the Toll-like receptors (TLR4 and TLR9) genes polymorphism in patients with Parkinson's disease in northern Iran. We extracted DNA from peripheral blood samples of 100 sporadic cases of Parkinson's disease and 100 healthy-matched controls with the mean age of 69.98 and 71.94 years, respectively. Subsequently, single-nucleotide polymorphisms (SNPs) of TLR4 and TLR9 were genotyped using restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). Results were confirmed employing Sanger sequencing. For the analysis of our data, we used SNPStats and SPSS 22 software. Our findings indicated that the allele distribution for rs352140 of TLR9 gene was significantly different in the PD group compared with the healthy controls (p=0.02). Moreover, rs352140 T allele was observed to be correlated with PD reduced risk (TT + TC vs. CC). The dominant rs352140 model was approved as the most acceptable inheritance model for fitting the data (OR 0.41, 95% CI 0.23-0.75, p=0.0031). Additionally, haplotype analysis revealed a significant correlation between TLR9 polymorphisms and Parkinson's disease. The results of this study indicated that rs352140T of TLR9 gene was a protective factor in Parkinson's disease. Furthermore, this SNP could be regarded as a prognostic factor. However, this conclusion should be confirmed by further investigations.