Probiotics Stimulate DRA Expression in Human Intestinal Caco‐2 Cells

Abstract

DRA (Down Regulated in Adenoma) plays a major role in apical Cl−/OH− (HCO3−) exchange process in the human intestine. Dysregulation of DRA has been implicated in diarrheal conditions, such as congenital chloride diarrhea and enteropathogenic infections. However, little is known about the regulation of DRA by probiotics, currently used as an alternative treatment for diarrhea. Therefore, the present studies were undertaken to determine the regulation of DRA expression and function by Lactobacilli in human intestinal Caco2 cells. Culture supernatant (CS) from an overnight grown Lactobacilli culture of ~1.5X107 CFU/ml was obtained and used at 1:50 dilution. L. rhamnosus or L. acidophilus CS treatment of Caco2 cells for 24h significantly increased (~2 fold) the relative abundance of DRA mRNA. To determine whether Lactobacilli alter the rate of DRA gene transcription, DRA promoter activity was assessed. Parallel to the increased mRNA expression, luciferase reporter gene assays showed ~2.5 fold increase in DRA promoter activity. Both L. rhamnosus or L. acidophilus stimulated Cl−/OH− exchange activity as measured by DIDS‐sensitive 36Cl− uptake (~ 50 %, P<0.05). These findings suggest that the soluble factors from Lactobacilli stimulate DRA expression and Cl− absorption and may aid in the development of novel therapeutic interventions for treatment of diarrheal disorders. (Supported by NIDDK and Dept of Veteran Affairs).