O0034 RECTAL PROBIOTIC ENEMAS INDUCE COLONIC MUCIN EXPRESSION WITH REDUCTION OF DSS-INDUCED COLITIS IN RATS

Abstract

Introduction: Mucins produced by intestinal epithelial cells function to protect the underlying intestinal mucosa from noxious substances. In in vitro cell culture systems probiotics upregulate mucin expression. The aim of this study was to evaluate the expression of colonic mucins and monitor the clinical course of rats following the rectal administration of a probiotic in the dextran-sulfate sodium (DSS) model of colitis. Methods: Pathogen-free Sprague-Dawley rats had access to a standard diet. Lactobacillus plantarum 299v (Lp299v) enemas of 3x109 colony forming units were administered for up to 7 days. At the time of enema administration, rats were offered water supplemented with 5% DSS to induce a distal colitis. The clinical course was recorded and following sacrifice, distal colonic segments were resected. Excised colons were washed, opened and their mucosal surfaces were scraped. Scrapings were placed in a solution containing 4M guanidine isothiocyante, 50mM sodium acetate and 250mM 2-mercaptoethanol. Total RNA was recovered by centrifugation through a 5.7M cesium chloride, 0.25M sodium acetate cushion and its integrity was verified by 1.2% agarose gel electrophoresis. Rat colonic mucin mRNA levels were analyzed by quantitative multiplex RT-PCR using a ABI Prism sequence detection system with primers and probes generated to rat Muc2 mucin. Mucin levels were normalized to simultaneously analyzed GAPDH mRNA levels and expressed relative to mRNA levels in control rats not receiving DSS water or Lp299v. Results: Colonic Muc2 mucin mRNA expression 2 days following Lp299v rectal enemas in rats drinking untreated water (160±21%, n=6) and in animals given both DSS water and Lp299v enemas for 2 days (241±27%, n=6) were both greater than control rats not receiving enemas or DSS water (p<0.05). Following 7 days exposure to DSS treated water only, Muc2 mRNA levels were also greater than in controls (177±29%, p<0.05). Only animals drinking DSS water but not receiving pro-biotic enemas that had clinical evidence of colitis. Conclusion: Probiotic enemas moderate the induction of DSS-induced colitis and upregulate Muc2 colonic mucin expression. Mucin upregulation is a mechanism whereby probiotics can reduce initiating events in the development of colitis from luminal factors responsible for its development.