Chapter 16 - Regulation of Mucosal Immunity in the Genital Tract: Balancing Reproduction and Protective Immunity

Abstract

More than 100 million new sexually transmitted infections (STIs) are acquired every day, with 357 million new infections each year caused by chlamydia, gonorrhea, syphilis, and trichomoniasis. At least 500 million people are estimated to have a genital herpes infection. Bacterial STIs are currently treatable with antibiotics, although antibiotic-resistant gonorrhea is becoming a major problem. Antivirals can be used to reduce symptoms and shedding of genital herpes but cannot cure latent infections. To date, vaccines have been developed only against human papillomavirus and hepatitis B, despite the recognition that vaccines represent the best means of halting this hidden STI epidemic. To facilitate successful reproduction, immunity in both the female and male reproductive tracts must be regulated. In females reproductive tract, immunity is regulated by sex hormones during pregnancy to allow successful implantation and growth to term of a semiallogeneic fetus. In males, sperm development begins at puberty, well after tolerance to self has developed. Therefore immune responses in the testes and epididymides must be suppressed to prevent autoimmunity against developing sperm and male infertility. These restraints on reproductive tract immune responses not only may provide opportunities for many sexually transmitted pathogens to establish chronic infections but also represent major challenges to the development of successful vaccines to target the major STIs. In this chapter, we describe how immunity in the female and male reproductive tracts is regulated to facilitate reproduction and discuss current research progress toward the development of vaccines for chlamydia and genital herpes.