Genetic Polymorphisms of IL6-174G/C, TNF-308G/A, and TNF-238G/A and Risk of Pleural Tuberculosis in Venezuelan Patients

Tuberculosis (TB) has various clinical presentations; pulmonary TB (PTB) affects only the lungs, whereas extrapulmonary TB involves other organs, including pleural TB (PLTB). Immunological studies of patients with extrapulmonary TB primarily focus on the cellular Th1 response, which produces key cytokines, including IFN-γ, TNF, IL-12, and IL-6. TNF and IL-6 play functional roles in host resistance to Mycobacterium tuberculosis (Mtb) infection. Findings suggest that TNF facilitates macrophage containment of Mtb, whereas IL-6 increases macrophage apoptosis induced by Mtb. Studies of the human genome have identified single-nucleotide polymorphisms (SNPs) in genes encoding cytokines associated with TB susceptibility. This study aimed to assess the potential of the IL6-174G/C (rs1800795), TNF-308G/A (rs1800629), and TNF-238G/A (rs361525) SNPs as genetic biomarkers of susceptibility to PLTB in the Venezuelan mestizo population. A total of 269 individuals were included: 69 patients with PLTB and 200 healthy individuals. The IL6-174G/C, TNF-308G/A, and TNF-238G/A polymorphisms were determined by sequence-specific primer polymerase chain reaction (SSP-PCR). Results showed significantly higher frequencies of the G/C, G/A, and G/A genotypes in patients with PLTB (94.0%, 94.2%, and 83.3%) than in controls (40.0%, 19.0%, and 13.4%) for the IL6-174G/C, TNF-308G/A, and TNF-238G/A polymorphisms, respectively. Logistic regression analysis showed significant associations between the G/C, G/A, and G/A genotypes and susceptibility to PLTB. The IL6-174G/C, TNF-308G/A, and TNF-238G/A gene polymorphisms may serve as genetic biomarkers of susceptibility to PLTB in the Venezuelan mestizo population.