Gastrointestinal neuromuscular apparatus: An underestimated target of gut microbiota

Figure 2 Role of toll-like receptors on human colonic smooth muscle cells. LPS affects intestinal contractility by activating oxidative stress in the mucosa and, once translocated, by activating TLR4 expressed in colonic muscle cells. Activation of muscular TLR4 impairs cell contractility by activation of the nuclear factor kB transcription with intracellular increase of oxidative stress and by prostaglandin E2 (PGE2) that block intracellular calcium release. The oxygen free radicals, produced in the mucosa, impair cell contractility with a similar mechanism and also by de-regulation of contractile receptors. The activation of TLR2, whose ligands are the components of the outer membrane of Gram-positive bacteria, such Lactobacillus rhamnosus GG (LGG), prevents LPS-induced muscular alterations. TLR4: Toll-like receptor 4; LPS: Lipopolysaccharide.