Activation of the TLR2 signaling pathway by GAPDH from bacterial strain RD055328.

We characterized the membrane vesicle fraction (RD MV fraction) from bacterial strain RD055328, which is related to members of the genus Companilactobacillus and Lactiplantibacillus plantarum. RD MVs and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were detected in the RD MV fraction. Immunoglobulin A (IgA) was produced by Peyer's patches cells following the addition of the RD MV fraction. In the presence of the RD MV fraction, RAW264 cells produced the pro-inflammatory cytokine IL-6. Recombinant GAPDH probably induced the production of IL-6 by RAW264 cells via superficial Toll-like receptor 2 (TLR2) recognition. A confocal laser scanning microscopy image analysis indicated that RD MVs and GAPDH were taken up by RAW264 cells. GAPDH wrapped around RAW264 cells. We suggest that GAPDH from strain RD055328 enhanced the production of IgA by acquired immune cells via the production of IL-6 by innate immune cells through TLR2 signal transduction.