Autophagy gene polymorphism is associated with susceptibility to leprosy by affecting inflammatory cytokines

Autophagy and inflammation closely interact with each other, and together, they play critical roles in bacterial infection. Leprosy is caused by the infection of Mycobacterium leprae (M. leprae). The objective of the study was to investigate the association between polymorphisms in IRGM, an autophagy gene, and susceptibility to leprosy, and identify possible functions of the polymorphism in the infection of M. leprae. Two polymorphisms in IRGM, rs4958842 and rs13361189, were tested in 412 leprosy cases and 432 healthy controls. Levels of inflammatory cytokines including interleukin 1 beta, IL-4, IL-6, and interferon gamma (INF-γ) were measured after the infection of M. leprae in the peripheral blood mononuclear cell (PBMC) of subjects with different genotypes of rs13361189. Data showed that prevalence of rs13361189TC and CC genotypes were significantly higher in leprosy patients than in healthy controls (odds ratio (OR) = 1.49, 95 % confidence interval (CI) 1.09-2.04, P = 0.012; OR = 2.58, 95 % CI 1.65-4.05, P < 0.001; respectively). Furthermore, the frequency of rs13361189CC genotype was increased in patients with complications than those without complications (P = 0.011). When analyzing the effect of rs13361189 polymorphism on M. leprae infection, we identified that M. leprae-infected PBMC with rs13361189CC genotype expressed significantly elevated levels of INF-γ and IL-4 than those with TT genotype. Our results suggested autophagy gene polymorphism was associated with the increased risk of leprosy by affecting inflammatory cytokines.