RNA-Based Anti-Inflammatory Effects of Membrane Vesicles Derived from Lactiplantibacillus plantarum .

Bacteria generally release extracellular membrane vesicles (MVs), which are nanoparticles that play important roles in bacterial-bacterial and bacterial-host communication. As probiotics, lactic acid bacteria provide diverse health benefits to their hosts. In this study, we found that the Gram-positive lactic acid bacteria Lactiplantibacillus plantarum subsp. plantarum NBRC 15891 produce high amounts of MVs ( Lp MVs), and that Lp MVs inhibit interleukin (IL)-8 production induced by lipopolysaccharide in intestinal epithelial HT29 cells. Heat- or UV-killed bacterial cells did not exhibit anti-inflammatory effects, and there was no uptake of these bacterial cells; contrarily, Lp MVs were taken up into the cytoplasm of HT29 cells. Small RNAs extracted from Lp MVs also suppressed IL-8 production in HT29 cells, suggesting that RNAs in the cytoplasm of bacterial cells are encapsulated in the MVs and released from the cells, which may be delivered to HT29 cells to exert their anti-inflammatory effects. In addition, administration of Lp MVs to mice with dextran sodium sulfate-induced colitis alleviated colitis-induced weight loss and colon length shortening, indicating that Lp MV intake is likely to be effective in preventing or ameliorating colitis.