Lactobacillus plantarum consumption increases PepT1-mediated amino acid absorption by enhancing protein kinase C activity in spontaneously colitic mice.

Abstract

Although probiotic consumption has generally been shown to have many beneficial effects for the prevention and treatment of inflammatory bowel disease, the effects of Lactobacillus plantarum (LP) on intestinal nutrient absorption, particularly oligopeptide transporter 1 (PepT1)-mediated absorption of dietary protein under inflammatory conditions, has not yet been characterized. In this study, we first investigated the effects of LP consumption on plasma amino acid concentrations and PepT1-mediated absorption of cephalexin in the small intestine of wild-type (WT) mice and interleukin-10 knockout (IL-10(-/-)) mice, a model of spontaneous colitis. We then analyzed expression and distribution of PepT1 and protein kinase C (PKC) activity in the jejunum of these mice. LP consumption (10(9) colony-forming units/0.5 mL) delivered by gavage once per day for 4 wk increased the total plasma amino acid concentration and the concentration of plasma cephalexin through enhancement of PepT1-mediated uptake in LP treated IL-10(-/-) mice compared with IL-10(-/-) mice. However, Western blotting and quantitative PCR analysis revealed no significant differences in PepT1 protein and mRNA expression between LP-treated and untreated mice. Additionally, immunofluorescence analysis showed that PepT1 did not appear to be mislocalized in IL-10(-/-) mice. Interestingly, IL-10(-/-) mice had significantly lower PKC activity and expression of phosphorylated PKC compared with WT mice, and these decreases could be prevented by LP treatment. These data suggest that consumption of LP enhances PepT1-mediated amino acid absorption, likely through alterations in PKC activity, as opposed to changes in expression or distribution of PepT1 in the small intestine of IL-10(-/-) mice.