Systematic review and meta-analysis of human Toll-like receptors genetic polymorphisms for susceptibility to tuberculosis infection

Epidemiological data from the world health organization (WHO) show that Globally an estimated 10 million (range, 8.9-11.0 million) people around the world were infected with TB in 2019. M.tuberculosis (M.tb) is the major cause of tuberculosis. Infection with M.tb has varied host immune responses because of the host genetic factor and its response to the infection. Genetic polymorphism in TLRs imparts susceptibility or resistance to the host against several diseases. In the present study, a systematic review and meta-analysis were performed to describe the relationship among various TLRs and SNPs involved in M.tb infection and their association with susceptibility to pulmonary tuberculosis in various populations of the world. PubMed and Scihub databases from 2008 to 2019 were searched and 58 articles were shortlisted for the present study to explore the association between TLRs gene polymorphisms and susceptibility to tuberculosis infection. The combined analysis showed that the polymorphisms TLR1 (rs5743618), TLR1 (rs4833095), TLR2 (-196 to -174) del, TLR2 (rs3804099), TLR4 (rs4986790), TLR4 (rs4986791), TLR4 (rs7873784), TLR6 (rs5743810), TLR8 (rs3764880), TLR9 (rs5743836), TLR9 (rs352139) were significantly associated with TB disease in certain ethnic population. In our meta-analysis study, we have also found variations between studies in some polymorphism, for example. The TLR1 (rs 5743618), TLR2 (rs5743708), TLR4 Asp299Gly, TLR4 Thr399Ile, TLR4 (rs7873784), TLR6 (rs5743810), TLR9 (rs5743836) was associated with the protection against TB. Meta-analysis was performed between polymorphisms and pulmonary tuberculosis to define increase or decrease in susceptibility to tuberculosis in various populations, which indicated that a relationship exists between SNPs/host genetic factors and susceptibility or resistance in patients suffering from pulmonary tuberculosis our finding concludes that this gene polymorphism may be associated with susceptibility to TB. The present study adds value to the various researches and studies going on various populations of the world in better understanding the role of TLR polymorphism in TB.