Lipoteichoic acid from Lactobacillus plantarum inhibits Pam2CSK4-induced IL-8 production in human intestinal epithelial cells

Lactobacilli are probiotic bacteria that are considered to be beneficial in the gastrointestinal tract of humans. Although lactobacilli are well known to alleviate intestinal inflammation, the molecular basis of this phenomenon is poorly understood. In this study, we investigated the effect of Lactobacillus plantarum lipoteichoic acid (Lp.LTA), which is a major cell wall component of this species, on the production of interleukin (IL)-8 in human intestinal epithelial Caco-2 cells. Treatment with Pam2CSK4, a synthetic lipopeptide that is known to mimic Gram-positive bacterial lipoproteins as an important virulence factor, significantly induced IL-8 expression in Caco-2 cells. However, neither heat-inactivated L. plantarum nor L. plantarum peptidoglycan inhibited Pam2CSK4-induced IL-8 mRNA expression. In addition, both a deacylated form and a dealanylated form of Lp.LTA failed to inhibit Pam2CSK4-induced IL-8 expression, indicating that the lipid and D-alanine moieties are critical for Lp.LTA-mediated inhibition. Moreover, Lp.LTA inhibited Pam2CSK4-induced activation of p38 kinase, JNK, and NF-κB transcription factor by suppressing toll-like receptor 2 activation. Collectively, these results suggest that Lp.LTA exerts anti-inflammatory effects on human intestinal epithelial cells by blocking IL-8 production.