Interleukin-10 gene promoter polymorphism as a potential host susceptibility factor in Pakistani patients with pulmonary tuberculosis

Tuberculosis (TB) is an infectious disease, which causes the death of nearly three million humans and eight million cases worldwide annually. Pakistan ranks the seventh position globally in terms of mycobacterium tuberculosis infection. TB susceptibility has been associated with cytokines polymorphism in different populations. Single nucleotide polymorphisms within the promoter region of interleukin-10 (IL-10) gene have been associated with altered levels of circulating IL-10, a Th2 cytokine that plays a key role in the pathogenesis of TB. We analyzed the frequencies of IL-10 promoter polymorphisms in 82 TB patients and 99 healthy Pakistani subjects using amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and results indicate that the allelic frequencies for the IL-10 -1,082 G/A, -819 C/T and -592 C/A did not differ significantly between the two groups. However, an association was found between TB occurrence and the IL-10 -1,082 GG genotype (p = 0.006, OR = 6.03), while the -1,082GA was predominant in healthy subjects (p = 0.013, OR = 0.29). Haplotype frequencies were similar in sick and health people. The diplotype GCC/ATA (intermediate IL-10 producer) predominates in Pakistani population, while the GCC/GTA (high) was associated with TB (p = 0.03, OR = 6.7) and GTA/ATA (intermediate) with healthy subjects (p = 0.03, OR = 0.23). Our findings therefore corroborates that the polymorphisms in IL-10 gene affect susceptibility to TB and increase risk of developing the disease.