Polysaccharide A can bind with MHC-II and the TLR2 receptor in plasmacytoid dendritic cells and then stimulate CD4+ Treg cells to secrete anti-inflammatory cytokine IL-10, which helps to protect against colitis.154 A previous study found that polysaccharide A stimulated the suppressive CD4(+)CD45RB(low) effector/memory T cells by forming polysaccharide A-MHCII complex, which induced anti-inflammatory responses.155 Sphingolipids are another group of bacterial membrane components that play a role in the functional interaction between gut microbiota and host metabolism. The gene discussed is CD4; the disease is colitis.