Regulatory T cells are locally induced during intravaginal infection of mice with Neisseria gonorrhoeae

Neisseria gonorrhoeae is a gram-negative diplococcus that in human beings produces gonorrhea. Much clinical evidence has led to the conclusion that gonococcus has important mechanisms to evade host immune functions; however, these mechanisms are only now beginning to be elucidated. In this study, we determined that the BALB/c mouse is a good animal model to study gonococcus infection and examined the immune response against the bacteria. We determined that after intravaginal inoculation of mice with Neisseria gonorrhoeae, the bacteria reached and invaded the upper female reproductive tissues and elicited a T-cell-specific immune response associated with a very weak humoral response, altogether resembling gonococcus infection and disease in women. Remarkably, in the draining lymph nodes of the genital tracts of infected mice, we found an increase of regulatory T lymphocytes, namely, transforming growth factor β1-positive CD4⁺ T cells and CD4⁺ CD25⁺ Foxp3⁺ T cells. Altogether, results indicate that N. gonorrhoeae induces regulatory T cells, which might be related to the local survival of the pathogen and the establishment of a chronic asymptomatic infection.