TRPV6 deficient mice are resistant to ethanol-induced disruption of colonic epithelial tight junctions, mucosal barrier dysfunction and liver damage (original) (raw)

Disruption of intestinal epithelial tight junctions (TJ), gut barrier dysfunction and endotoxemia play important role in the pathogenesis of alcoholic liver disease (ALD). Our previous study showed that Ca2+ influx and TRPV6 channel play crucial role in ethanol (EtOH) and acetaldehyde induced TJ disruption and barrier dysfunction in Caco-2 cell monolayers. In the present study, we evaluated the effect of EtOH feeding on gut and liver injury in TRPV6 knockout (TRPV6-/-) mice. Wild type (WT) and TRPV6-/mice were fed 1e6% EtOH (0% 2d, 1% 2d, 2% 2d, 4% 1 wk, 5% 1 wk and 6% 1 wk) in Lieber-DeCarli liquid diet; control mice were pair fed iso-caloric maltodextrin. Colon length was slightly, but significantly, increased by EtOH feeding in WT mice, but not in TRPV6-/-mice. EtOH feeding elevated inulin permeability in the distal colon in vivo in WT mice, which was associated with redistribution of TJ proteins from the junctions. EtOH failed to alter colonic epithelial permeability and TJ disruption in TRPV6-/mice. Plasma endotoxin level was increased by EtOH feeding in WT mice, but not in TRPV6-/-mice. Actin cytoskeletal architecture in the colonic epithelium was disrupted by EtOH feeding in WT mice, which was associated with activation of cofilin. EtOH feeding increased liver triglyceride level, which was associated with histological lesions and elevated plasma AST/ALT in WT mice. EtOH-induced liver injury and plasma AST/ALT elevation were minimal in TRPV6-/-mice. In WT mice, EtOH depleted reduced protein thiols and elevated oxidized protein thiols in colonic epithelium and liver, which was associated with down regulation of antioxidant genes (SOD1, SOD2, Trx1, catalase, GPX1 & Nrf2); these effects of EtOH were minimal in TRPV6-/-mice. EtOH feeding up regulated inflammatory cytokine (IL-1b & TNFa) and chemokine (MCP-1, CCL5, CXCL1 & CXCL2) gene expression in WT mice, but not in TRPV6-/-mice. These data demonstrate that TRPV6 plays an important role in EtOH-induced colonic epithelial TJ disruption, mucosal barrier dysfunction, endotoxemia and liver damage, and that TRPV6 channel blockers may bear therapeutic value in the treatment of ALD and other alcohol-related diseases. (Supported by NIH R01 AA12307 (RKR) and R01 DK55532 (RKR).) 20. Impact of repeated binge drinking on resistance to bacterial pneumonia