Administration of Antibiotics Downregulates the Expression of MicroRNA-200 Family Members in Lamina Propria T Cells of the Murine Large Intestine.

By comparing germ-free mice and specific pathogen-free mice, we previously demonstrated that gut commensals upregulate the expression of microRNA-200 family members, i.e., miR-200a, miR-200b, miR-200c, miR-141, and miR-429, in lamina propria leukocytes (LPLs) of the murine large intestine, and that it results in decreased production of interleukin-2, which is mainly produced by activated CD4⁺ T cells. In the present study, we investigated whether depletion of the gut microbiota by antibiotic treatment reduces the expression of miR-200 family members in T cells of the large intestinal lamina propria in mice. Supplementation of drinking water with antibiotics for 1 wk reduced the number of cecal bacteria in male C57BL/6J mice. LPLs of the large intestine were isolated and separated into T-cell and non-T-cell fractions by magnetic-activated cell sorting. Reverse transcription-quantitative polymerase chain reaction results showed that the expression levels of miR-200 family members were higher in the T-cell fraction than in the non-T-cell fraction, and were lower in the T-cell fraction of the antibiotic-treated mice than in that of the control mice. These results suggest that antibiotic-sensitive gut commensals upregulate the expression of miR-200 family members primarily in the T cells of the large intestinal lamina propria in mice.