Lactobacillus acidophilus counteracts enteropathogenic E. coli-induced inhibition of butyrate uptake in intestinal epithelial cells

Regulation of colonic epithelial butyrate transport: Focus on colorectal cancer

Highlights

Fermentation of the dietary fiber by intestinal microflora results in production of butyrate.Butyrate possesses anticarcinogenic effect at the colonic level.Three transporters (MCT1, SMCT1 and BCRP) regulate the intracellular concentration of BT in colonic epithelial cells.Changes in the expression of these transporters occur in colorectal cancer.

Abstract

Colorectal cancer (CRC) is one of the most common solid tumors worldwide. Consumption of dietary fiber is associated with a low risk of developing CRC. The fermentation of the dietary fiber by intestinal microflora results in production of butyrate (BT). This short-chain fatty acid is an important metabolic substrate in normal colonic epithelial cells and has important homeostatic functions at the colonic level. Because the cellular effects of BT (e.g. inhibition of histone deacetylases) are dependent on its intracellular concentration, knowledge on the mechanisms involved in BT membrane transport and its regulation seems particularly relevant. In this review, we will present the carrier-mediated mechanisms involved in BT membrane transport at the colonic epithelial level and their regulation, with an emphasis on CRC. Several xenobiotics known to modulate the risk for developing CRC are able to interfere with BT transport at the intestinal level. Thus, interference with BT transport certainly contributes to the anticarcinogenic or procarcinogenic effect of these compounds and these compounds may interfere with the anticarcinogenic effect of BT. Finally, we suggest that differences in BT transport between normal colonocytes and tumoral cells contribute to the "BT paradox" (the apparent opposing effect of BT in CRC cells and normal colonocytes).

Probiotics and Innate and Adaptive Immune Responses in Premature Infants

Premature infants are at increased risk for morbidity and mortality due to necrotizing enterocolitis (NEC) and sepsis. Probiotics decrease the risk of NEC and death in premature infants; however, mechanisms of action are unclear. A wide variety of probiotic species have been evaluated for potential beneficial properties in vitro, in animal models, and in clinical trials of premature infants. Although there is variation by species and even strain, common mechanisms of protection include attenuation of intestinal inflammation, apoptosis, dysmotility, permeability, supplanting other gut microbes through production of bacteriocins, and more effective use of available nutrients. Here, we review the most promising probiotics and what is known about their impact on the innate and adaptive immune response.

Short chain fatty acids mediated flora-host interaction and irritable bowel syndrome

Intestinal flora has proved to be closely related to the onset of irritable bowel syndrome (IBS). Short chain fatty acids (SCFAs) are the main product of flora metabolism as well as important messenger molecules in the gut, playing a role in maintaining the stability of microorganism community structure and in regulating intestinal immune response, motility and the epithelial barrier. Flora imbalance in IBS patients has a direct impact on the microbiota-SCFAs-intestinal epithelial cells signal pathway, which results in low-grade inflammation, increased intestinal permeability and abnormality of motility. Studying the role SCFA plays in the pathogenesis of IBS can expand our understanding of this disease and provide a new strategy for therapy.