Time-dependent disruption of oviduct pacemaker cells by Chlamydia infection in mice

Chlamydia trachomatis is the most commonly reported infectious disease in the United States. In women, this infection can lead to pelvic inflammatory disease and cause ectopic pregnancy and tubal factor infertility. Oviduct interstitial cells of Cajal (ICC-OVI) have been identified as pacemakers, responsible for generating slow waves that underlie myosalpinx contractions that are critical for egg transport. ICC-OVI are damaged in mice by the host inflammatory response to Chlamydia, leading to loss of pacemaker activity and associated contractions. However the inflammatory mediator(s) that causes this damage has not been identified. Mice resolve C. muridarum 3-4 wk postinfection but it remains unexplored whether ICC-OVI and pacemaker activity recovers. We have investigated the time dependence of C. muridarum infection with respect to ICC-OVI loss and examined the inflammatory mediator(s) that may be responsible for this damage. Intracellular recordings from the myosalpinx were made at 1, 2, 4 and 7 wk postinfection with Chlamydia. Immunohistochemistry was performed at similar time points to examine changes in ICC-OVI networks and expression of nitric oxide synthase 2 (NOS2) and prostaglandin synthase 2 (PTGS2). Chlamydia-induced expression of NOS2 occurred in stellate-shaped, macrophage-like cells, and damage to ICC-OVI and pacemaker activity occurred as NOS2 expression increased. Immunohistochemistry revealed that macrophages were in close proximity to ICC-OVI. Changes to ICC-OVI were not correlated with PTGS2 expression. These data suggest that ICC-OVI networks and pacemaker activity may be damaged by nitric oxide produced in NOS2-expressing macrophages in response to C. muridarum infection. As the infection resolves, NOS2 expression decreases, ICC-OVI networks recover, and pacemaker activity resumes.