Chlamydia trachomatis and Chlamydophila abortus induce the expression of secretory leukocyte protease inhibitor in cells of the human female reproductive tract.

C. trachomatis and C. abortus are related Gram-negative intracellular bacteria that cause reproductive failure due to infertility (C. trachomatis) or abortion (C. abortus). These organisms target epithelial cells in the reproductive tract and/or placenta, but the innate immune mechanisms that lead to protection or pathology and disease are poorly understood. SLPI is an innate immune molecule which protects mucosal surfaces from infection and injury. C. trachomatis and C. abortus were found to induce SLPI mRNA and peptide expression in HeLa (cervical epithelium) and JEG-3 cells (trophoblast) respectively. Both cell lines constitutively expressed SLPI and, although infection enhanced this expression, killed organisms did not. These data demonstrate that Chlamydia/Chlamydophila grow in cells that express SLPI, suggesting that SLPI does not exert antimicrobial effects against these organisms. However, SLPI has multiple functions, and we speculate that it may play a role in controlling tissue inflammation and pathology.