Development and evaluation of in vitro intestinal epithelial models to study ameliorative effects of probiotics on inflammation induced barrier dysfunction

Abstract

The human intestinal epithelium constitutes major component of the body’s interaction with the external environment. In addition to performing physiological functions such as digestion and absorption of nutrients, this epithelium provides a defensive barrier from the microflora colonizing the lumen. Inhabitation of the lumen with pathogenic bacteria causes inflammtion and compromise in integrity of this barrier. A compromised intestinal barrier is observed in numerous patho-physiological disorders such as Crohn’s disease, Inflammatory Bowel Disease, Type 2 Diabetes, etc. and in addition, alteration in the profile of the microflora is observed in various diseases. To understand the role of these bacteria in modulating inflammations and barrier function we aimed to develop an in vitro model. CaCO2 cell line based 5 day and 21-day monolayers are used to study the permeability characteristics of the intestine with good correlation to intestinal epithelium. Using these 5-day and 21-day monolayers we tried to study the effect of inflammations on the integrity of the barrier. Although it is reported in the literature that short term monolayers are suitable to study the permeability in the intestine, they are unsuitable for studying inflammation induced barrier dysfunction in the epithelium as explored by us. The 21-day CaCO2 monolayers remain a stable option for studying intestinal barrier characteristics and inflammations from cytokines and immune system can affect the barrier integrity. These compromised barriers can be restored by using metabolites of probiotics Bifidobacterium lactis Bb12; however supernatant of commercially available L casei shirota did not alleviate the inflammation induced barrier dysfunction indicating that this is a species specific phenomenon.