S1786 Enteric Glial Cells Through a NOS-Dependent Pathway Regulate the Intestinal Barrier Function in an Acute Ischemia/Reperfusion Rat Model

Abstract

G A A b st ra ct s gut permeability. Methods: The protocol for the use of mice was approved by the Animal Care and Use Committee. We measured PM induced cell death and mitochondrial ROS generation in CaCo2 cells stably expressing oxidant sensitive GFP localized to mitochondria in the absence or presence of an antioxidant (a combined catalase/SOD mimetic). C57Bl6 mice were exposed to PM less than 2.5μ (PM2.5) from Washington, DC or saline via gastric gavage and small bowel and colonic tissue were harvested for histologic evaluation, and RNA isolation at 24 and 48 hours. Permeability to 4kD dextran was measured at 48 hours. Results: Exposure of CaCo2 cells to PM induced dose-dependent mitochondrial ROS generation and cell death, which were both reversible with antioxidant. Exposure to PM also caused oxidant-dependent NF-κB activation, increased permeability (measured by transepithelial resistance), and disruption of tight junctions (with ZO-1 staining) in CaCo2 monolayers. Mice exposed to PM had normal small bowel and colonic histology, but an 8fold increase in colonic cell apoptosis by TUNEL staining, a 40% increase in intestinal permeability, time dependent increase IL-6 mRNA and in contrast a time-dependent reduction in ZO-1 mRNA in the colon compared to control mice treated with saline. Conclusions: This is the first report demonstrating that exposure to PM causes oxidant dependent GI epithelial cell death, disruption of tight junctional proteins, inflammation and increased permeability in the gut In Vitro and In Vivo. These PM-induced changes may be may be responsible for exacerbations of inflammatory disorders of the gut.