Association of toll-interacting protein (TOLLIP), il-1β and il-10 gene polymorphisms and expression of negative regulators of human innate immune response with susceptibility to tuberculosis

Tuberculosis (TB) is one of the leading causes of infectious death in humans worldwide, yet its immune pathogenesis remains incompletely understood. The innate immune response is critical for the initial host defense against mycobacteria. which regulate host immune response host immunogenetic risk factors. In this context, it has been proposed in few molecular studies that various polymorphisms of genes encoding the effectors such as IL-1β, a pro-inflammatory cytokine, and IL-10, an anti-inflammatory cytokine, and Toll-interacting protein (TOLLIP), one of mediators negatively regulating inflammatory response by interacting with Toll-Like Receptors (TLRs), and gene expression levels of negative regulators of immune response play an important role in the pathophysiology of TB and susceptibility to TB as well as in many chronic infections in different human populations. In our study, we aimed to research the association of these host risk factors with susceptibility to tuberculosis. After the examination of sputum samples sent from Adana province to CU THAUM Regional Tuberculosis Laboratory between December, 2015 and December, 2017, 8 ml venous blood samples were collected in EDTA-containing tubes from the consecutive 50 TB patients and 50 TB-negative healthy controls. After the DNA extraction from 2 ml of the samples, the rs5743899A/G and rs3750920C/T polymorphisms of the TOLLIP gene and the IL-1β +3954C/T polymorphism were investigated by using Polymerase Chain Reaction - Restriction Fragment Length Polymorphism (PCR-RFLP) assay, whereas the IL-10 -1082G/A polymorphism was examined by using Amplification Refractory Mutation System - Polymerase Chain Reaction (ARMS-PCR) assay. After the isolation of mononuclear cells from the remaining 6 ml of the samples, RNA was extracted, and the gene expression levels of negative regulators of immune response such as A20, SOCS1, SOCS3, SIGIRR, ST2, TOLLIP, MKP1, IRAK-M were investigated by using quantitative Real-Time PCR assay. The study will further reveal the importance of these markers for tuberculosis, and obtained data will shed light on the design of new vaccines and drugs. Besides, by genotyping the MTBC isolates, association of host factors with reactivation/reinfection will have been examined at the end of our study. The expression of negative regulators significantly increased in ST2, TOLLIP ve SIGIR, while decreased in IRAK-M ve MKP1. Although the polymorphisms were not separately associated with TB, even more significant relationships were determined when evaluated together with the expressions of negative regulators. As far as we know, our research is the first study in which these immune mediators are evaluated together and associated with sensitivity to TB. In conclusion, we assumed that, immunopathogenesis of TB will be better understood owing to the overall evaluation of these host biomarkers together in addition to the rapid diagnosis, therefore, our study will contribute to the reorganisation of control and treatment protocols and shed light on surveillance studies with wider populations.