Nuclear factor-kappa B directs carcinoembryonic antigen-related cellular adhesion molecule 1 receptor expression in Neisseria gonorrhoeae-infected epithelial cells.

Abstract

The human-specific pathogen Neisseria gonorrhoeae expresses opacity-associated (Opa) protein adhesins that bind to various members of the carcinoembryonic antigen-related cellular adhesion molecule (CEACAM) family. In this study, we have analyzed the mechanism underlying N. gonorrhoeae-induced CEACAM up-regulation in epithelial cells. Epithelial cells represent the first barrier for the microbial pathogen. We therefore characterized CEACAM expression in primary human ovarian surface epithelial (HOSE) cells and found that CEACAM1-3 (L, S) and CEACAM1-4 (L, S) splice variants mediate an increased Opa(52)-dependent gonoccocal binding to HOSE cells. Up-regulation of these CEACAM molecules in HOSE cells is a direct process that takes place within 2 h postinfection and depends on close contact between microbial pathogen and HOSE cells. N. gonorrhoeae-triggered CEACAM1 up-regulation involves activation of the transcription factor nuclear factor kappaB (NF-kappaB), which translocates as a p50/p65 heterodimer into the nucleus, and an NF-kappaB-specific inhibitory peptide inhibited CEACAM1-receptor up-regulation in N. gonorrhoeae-infected HOSE cells. Bacterial lipopolysaccharides did not induce NF-kappaB and CEACAM up-regulation, which corresponds to our findings that HOSE cells do not express toll-like receptor 4. The ability of N. gonorrhoeae to up-regulate its epithelial receptor CEACAM1 through NF-kappaB suggests an important mechanism allowing efficient bacterial colonization during the initial infection process.