IL-10 high producing genotype predisposes HIV infected individuals to TB infection

Interleukin (IL-10), an anti-inflammatory cytokine, is known to have dual effect on the host immune system. One of these roles is that it provides an effective autoregulatory mechanism which protects the host from excessive inflammation and tissue damage which is in part initiated by the Th1 driven pro-inflammatory immune responses during infections (such as TB, HIV and malaria). However, though beneficial, this autoregulatory mechanism is at times exploited by pathogens which evade elimination by Th1 driven immune response leading to chronic infections. The main aim of this study therefore was to study the influence of IL-10 polymorphism in relation to its levels with respect to HIV-TB co-infection. A total of 452 participants were categorized into HIV (121), active tuberculosis (TB) (118), HIV-TB (HT) (106) groups and healthy control group (107). Polymorphism for IL-10 gene (positions -1082, -819, -592) was studied using ARMS-PCR, RFLP. IL-10 and IFN-γ levels in antigen stimulated cultures were measured using ELISA. Statistical analysis was performed using Chi-Square (χ(2)) test, One-way ANOVA and t-tests. IL-10 (-1082) GG genotype was positively associated with HIV-TB, whereas AG with HIV and AA with TB. The cohort with GG genotype also had significantly high stimulated levels of IL-10 compared to AG and AA. AC genotype was significantly frequent in HIV-TB group at IL-10 (-592) position when compared with controls. HIV positive individuals with GG genotype at IL-10 (-1082) position and high IL-10 levels may have a high risk of developing TB co-infection.