HUMAN INTESTINAL EPITHELIAL CELL LINES AS IN VITRO TOOLS FOR STUDYING THE SECRETORY CHANGES IN RESPONSE TO ENTEROPATHOGENIC ESCHERICHIA COLI INFECTION

Abstract

111 Infections with Enteropathogenic Escherichia Coli (EPEC) are common in infants and children in developing countries. They also play an important role in the immune compromised host. The pathogenesis of the resulting diarrhea remains unclear. EPEC adhere to the enterocytes and produce the characteristic "attaching and effacing" A/E lesions of the brush border membrane. The goal of this study is to characterize the in-vitro secretory changes in the different intestinal epithelial cell models in response to EPEC infection. Several intestinal epithelial cell monolayers were used in this study. HT-29 cells, which are colon cancer cells known to differentiate in the absence of glucose, were used in this study. In addition, two clones of the HT-29 cells namely HT-29 C119A; which are suitable for studying electrolyte transport, HT-29 16E; which contain active mucus secreting cells, and finally CaCo2; which are another type of colon cancer cells, were also used. The cells were allowed to become confluent on a transwell insert, then were rapidly infected with EPEC E2348/69. Another set of transwell inserts served as the control group. The short circuit current (Isc) and the transepithelial conductivity were measured at 5 minutes, then at 10-60 minutes in 10-minute intervals. Comparisons between the control group and the EPEC infected cells (n=8) were made using two-way analysis of variance with repeated measures over time periods. A significant increase in the Isc as well as the transepithelial conductivity was noted in response to EPEC infection with the CaCo2 cells (Isc overall mean±S.D. = 3.2±1.1uA/cm2 for the control group, versus 14.1±3.6 for the EPEC group, p <0.0001; conductivity=6.2±1.9 mS versus 8.0±1.8, p<0.05). The differentiated as well as the undifferentialed HT-29 cells with its clones did not mount a significant secretory response to EPEC. In conclusion, CaCo2 cells can serve as an important in vitro model for further future studies of the secretory changes resulting from EPEC infection.