By studying the expression of different genes, it was observed that the probiotic strain L. plantarum Lp91 caused a significant decrease in the levels of TNFα (tumor necrosis factor α) and COX-2 (cyclooxygenase-2) in a mouse model of colitis, and this effect was related to significant increases of IL-10 expression [12]. This evidence concerns the gene PTGS2 and colitis.