Investigating the association of toll-like receptor 9 rs5743836, rs352140, and rs187084 gene polymorphisms and their mRNA levels with different hepatic fibrosis stages of non-alcoholic fatty liver patients compared to healthy controls

Recent studies have shown that the level of hepatocyte-derived mitochondrial DNA is elevated in plasma samples obtained from mice and NASH patients, and it has the ability to toll- like receptor 9 (TLR9) activation resulting in steatosis, hepatocyte injury, and fibrosis. In this study, we explored the association between TLR9 rs5743836, rs352140, and rs187084 polymorphism and its plasma mRNA level in non-alcoholic fatty liver (NAFL) patients with different liver fibrosis scores compared to healthy controls. Seventy Iranian patients diagnosed with NAFL, based on fibroscan testing results, were divided into F0-F1 (N=33), F2-F3 (N=19), and F4 (N=18) hepatic fibrosis groups and compared to 22 healthy controls. Genotyping was done using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the mRNA expression level of TLR9 was determined using Real-Time PCR analysis. Results showed no significant association between allelic and genotypic distribution frequency of TLR9 rs5743836, rs352140, and rs187084 polymorphisms in NAFL patients with hepatic fibrosis compared to healthy controls (P>0.05). However, the mRNA level of TLR9 was significantly elevated in correlation with hepatic fibrosis progression in NAFL patients compared to healthy controls (P<0.05). As a preliminary study, our data showed a correlative overexpression of TLR9 mRNA with hepatic fibrosis progression in NAFL patients without the effectiveness of TLR9 gene polymorphisms.