Role of Intestinal Circadian Genes in Alcohol-Induced Gut Leakiness

Abstract

Background Several studies have indicated that endotoxemia is the required co-factor for alcoholic steatohepatitis (ASH) that is seen in only about 30% of alcoholics. Recent studies have shown that gut leakiness that occurs in a subset of alcoholics is the primary cause of endotoxemia in ASH. The reasons for this differential susceptibility are not known. Since disruption of circadian rhythms occurs in some alcoholics and circadian genes control the expression of several genes that are involved in regulation of intestinal permeability, we hypothesized that alcohol induces intestinal hyperpermeability by stimulating expression of circadian clock gene proteins in the intestinal epithelial cells. Methods We used Caco-2 monolayers grown on culture inserts as an in vitro model of intestinal permeability and performed western blotting, permeability, and siRNA inhibition studies to examine the role of Clock and Per2 circadian genes in alcohol-induced hyperpermeability. We also measured PER2 protein levels in intestinal mucosa of alcohol fed rats with intestinal hyperpermeability. Results Alcohol, as low as 0.2%, induced time dependent increases in both Caco-2 cell monolayer permeability and in CLOCK and PER2 proteins. SiRNA specific inhibition of either Clock or Per2 significantly inhibited alcohol-induced monolayer hyperpermeability. Alcohol-fed rats with increased total gut permeability, assessed by urinary sucralose, also had significantly higher levels of PER2 protein in their duodenum and proximal colon than control rats. Conclusions Our studies: (1) demonstrate a novel mechanism for alcohol-induced intestinal hyperpermeability through stimulation of intestinal circadian clock gene expression, and (2) provide direct evidence for a central role of circadian genes in regulation of intestinal permeability.

Short-Chain Fatty Acids Activate AMP-Activated Protein Kinase and Ameliorate Ethanol-Induced Intestinal Barrier Dysfunction in Caco-2 Cell Monolayers

“…The concentration of ethanol used in our study is not cytotoxic as shown previously that ethanol at a concentration of 0.2% v:v (;40 mmol/L), which can be achieved in blood after moderate (2-4 drinks; 1 standard drink, ;14 g of ethanol) consumption (30,31), can disrupt epithelial TJ integrity in a Caco-2 3-dimensional cell culture model without compromising cell viability (3). Our findings are also in agreement with previous observations by others showing that ethanol can disrupt the TJ integrity, resulting in increased paracellular permeability (30,(32)(33)(34).…”

High C-Reactive Protein Is Associated with Poor Sleep Quality Independent of Nocturnal Symptoms in Patients with Inflammatory Bowel Disease

“…In a different cohort, while disease related symptoms was a key determinant of impaired sleep quality, poor sleep even during remission was associated with an increased risk of symptomatic disease flares at 6 months 10 . Experimentally, interleukin-6 (IL-6), interleukin-1 (IL-1), and tumor necrosis factor (TNF) directly induces fatigue and sleep 22–24, 38–40 . Intravenous or intra-cerebroventricular injections of recombinant TNF suppresses rapid-eye-movement (REM sleep) 34 .…”

Decreased melatonin secretion is associated with increased intestinal permeability and marker of endotoxemia in alcoholics

“…A method of assessing integrity of peripheral circadian homeostasis is the measurement of core circadian genes such as CLOCK and PER genes in circulating blood monocytes or tissue clock genes in intestine or liver. Our recent work showed that alcohol in-creased circadian clock genes, CLOCK and PER2, in intestinal epithelial cells, CaCo-2 cells, and blocking CLOCK or PER2 with small-interfering RNA prevented alcohol-induced hyperpermeability (44). Our subsequent studies in mice have shown that circadian disruption, either environmental or genetic, increases alcohol-induced intestinal permeability and liver injury (43).…”