Infection of polarized primary epithelial cells from rat uterus with Chlamydia trachomatis: Cell-cell interaction and cytokine secretion

PROBLEM: The objective of this study was to examine the susceptibility of r at uterine epithelial cells (UEC) to infection with Chlamydia trachomatis a nd to study the epithelial-stromal interactions following infection. METHOD OF STUDY: UEC were isolated from adult rats and grown in culture. Po larized, confluent monolayers of UEC were infected with 10(6) IFU/well C. t rachomatis (MoPn). In order to confirm infection, MoPn was labeled with a. fluorescent tracking dye, PKH-26, and then used in epithelial cell infectio ns. Transepithelial resistances were measured prior to and following infect ion to test the effect of Chlamydia on the integrity of the epithelial mono layers. In other experiments, polarized epithelial cultures were infected i n the presence and absence of stromal cells. Media was collected from the a pical and basolateral compartments of the cultures before and after infecti on and analyzed for cytokines IL-1 alpha and TNF-alpha. RESULTS: Epithelial cell cultures infected with PKH-26 labeled MoPn were ex amined 4-5 days later. Bacterial inclusions were detected inside epithelial cells indicating infection had occurred. Co-localization of PKH-26 labeled bacteria with FITC-labelled anti-Chlamydia antibody on the epithelial cell s confirmed infection. No changes were found in resistance across the monol ayers of epithelial cells in the presence or absence of infection. ELISA re sults indicate that UEC secrete IL-1 alpha constitutively in vitro. Stromal cells secrete very little IL-1 alpha. When stromal cells were co-incubated with epithelial cells there was a decrease in the amount of IL-1 alpha sec reted by epithelial cells 48 hr post-infection. On the other hand, maximum TNF-alpha was found in stromal cells, both with and without infection. Epit helial cells, in these studies made very little TNF-alpha. CONCLUSIONS: These results show that primary rat epithelial cells can be in fected with Chlamydia in vitro. Epithelial and stromal cells from uteri of adult rats make IL-1 alpha and TNF-alpha in vitro both prior to and followi ng infection with Chlamydia. This system can be used to analyze the role pl ayed by epithelial-stromal interactions in providing protection on this muc osal surface.