Suppression of host adaptive immune responses by Neisseria gonorrhoeae: role of interleukin 10 and type 1 regulatory T cells

Infection with Neisseria gonorrhoeae triggers an intense inflammatory response characterized by an influx of neutrophils in the genital tract, yet natural gonococcal infection does not induce a state of protective immunity. Our previous studies in a mouse model of N. gonorrhoeae infection demonstrated that transforming growth factor-beta (TGF-beta) is involved in the suppression of adaptive immunity by this organism, but complete inhibition of TGF-beta activity only partially reverses N. gonorrhoeae-mediated suppression of T helper type 1 (Th1) and Th2 responses. In this study, we show that N. gonorrhoeae strongly induced the production of interleukin (IL)-10 and type 1 regulatory T (Tr1) cells. Blockade of IL-10 and Tr1 cell activity enhanced both Th1/Th2-dependent adaptive immune responses and Th17-governed innate responses to N. gonorrhoeae. Treatment of mice with anti-IL-10 antibody during gonococcal challenge led to faster clearance of infection and induced protection against secondary infection, with the generation of circulating and vaginal anti-gonococcal antibodies. Our results suggest that inhibition of IL-10 and Tr1 cells affords a new approach to the treatment of gonorrhea and facilitates the development of specific protective immunity.