Lipopolysaccharide induces expression of genes encoding pro-inflammatory cytokines and the elastin-degrading enzyme, cathepsin S, in human cervical smooth-muscle cells

OBJECTIVE: Vaginal and amniotic infection with gram-negative bacteria is as sociated with preterm birth. We previously reported that human cervical smo oth-muscle cells (CSMC) respond to pro-inflammatory cytokines by expressing enzymes that degrade the extracellular matrix. Our objective was to charac terize the effects of lipopolysaccharide (LPS) from Escherichia coli (E col i), Bacteroides fragilis, (B frag) and Fusobacterium nucleatum (F nuc) on t he expression of pro-inflammatory cytokines and the elastin-degrading enzym e, cathepsin S, in human CSMC. METHODS: Human CSMC were exposed to LPS and the expression of mRNAs encodin g pro-inflammatory cytokines and cathepsin S, and selected matrix metallopr oteinases (MMPs) was analyzed by Northern blotting. The effect of cytokine- neutralizing antibodies on LPS-induced cathepsin S mRNA expression also was determined. RESULTS: E coli LPS increased expression of cathepsin S 12.5-fold after 12 hours; MMP-1 and MMP-3 mRNAs also were increased 2.9- and 3.5-fold, respect ively. Tumor necrosis factor (TNF)-alpha, interleukin (IL-1)alpha, and IL-1 beta RNAs were markedly up-regulated after 3 hours of LPS treatment. B fra g and F nuc LPS also induced TNF-alpha and cathepsin S mRNAs. E coli LPS ca used a sevenfold increase in TNF-alpha secretion after 5 to 8 hours. Antihu man TNF-alpha monoclonal antibody, but not a monoclonal antibody to the low -density lipoprotein receptor, reduced the LPS-induced increase in cathepsi n S mRNA by 27%, whereas neutralizing antibodies against IL-1 alpha and IL- 1 beta did not suppress the response. Human CSMC were shown ro express the toll-like receptor (TLR-2) and TLR-4 genes, which mediate the action of LPS . TLR-2 mRNA was up-regulated by TNF-alpha. CONCLUSION: CSMC respond to LPS with increased expression of pro-inflammato ry cytokines and cathepsin S. Increases in cathepsin S mRNA result only in part from the rapid induction of TNF-alpha gene expression. TNF-alpha may a lso augment the CSMC response to LPS by increasing expression of the LPS si gnaling receptor, TLR-2, which probably directly mediates LPS action. These observations provide a mechanism by which gram-negative bacteria can preci pitate cervical changes associated with preterm birth. Copyright (C) 2000 b y the Society for Gynecologic Investigation.