Solute carriers (SLC) in inflammatory bowel disease: a potential target of probiotics?

Transporter proteins of the solute carriers (SLCs) family play a role in epithelial permeability and barrier function in the intestine, and polymorphisms in SLC genes are associated with inflammatory bowel disease. Many SLCs also mediate the bioavailability of pharmaceutical compounds, and the modulation of such transport systems to increase drug efficacy is, therefore, of great interest. We have undertaken a large-scale project to evaluate whether bacteria can modulate the expression of SLCs in the intestine. Here we report the effect of VSL[sharp]3 (a high-potency probiotic preparation) on the expression of 3 large solute carrier families, SLC4, SLC21, and SLC22, which are involved in the transport of bicarbonates, organic anions and cations, and affect the bioavailability of several pharmaceutical compounds. Two groups of animals (VSL[sharp]3 and phosphate-buffered saline controls) were studied for SLC expression in the intestine by Real-Time PCR at the beginning (day 1) and at the end (day 20) of the treatment, and 7 days after the interruption of the treatment. An effect of VSL[sharp]3 administration was detected on the expression of 10% of the studied genes. This reached statistical significance (P=0.01) for the poorly characterized sodium-borate cotransporter SLC4A11, which showed a 5-times lower expression in VSL[sharp]3 than in control mice on day 1 of probiotic treatment. VSL[sharp]3-driven changes in the expression levels of SLC transporters might contribute to its reported effects on intestinal permeability. The elucidation of SLC4A11 function in the intestine will be the key to fully evaluate the relevance of specific findings.