Loss of Intestinal Epithelial AMPK Does Not Alter Susceptibility to Acute Chemical Colitis or Bacterial Infection
Authors: King Stephanie J , Batugedara Hashini M , Jones Russell G , Nair Meera G , McCole Declan F 
Published: June 2021

AMP‐Activated Protein Kinase (AMPK) is a master regulator of cellular energy status. Its primary actions are mediated by its alpha catalytic subunit, which has two isoforms. Previous evidence in mice has suggested that loss of an individual AMPK‐α isoform compromises critical functions of the intestinal epithelium such as tight junction permeability while intact AMPK activity is protective against mucosal inflammation. These processes are essential to maintain the intestinal barrier and prevent chronic inflammation. However, AMPK‐dependent effects under cellular stress conditions have not been consistent and appear context‐dependent. Additionally, published studies have not confirmed whether AMPK is necessary and sufficient for these effects. The goals of this study were to determine if AMPK is required to protect from mouse models of acute colitis.

Methods

Deletion of AMPKα specifically in intestinal epithelial cells was accomplished by crossing Prkaa1/2 floxed mice with Villin‐Cre mice. Dextran sulfate sodium (DSS) colitis was induced in conventionally housed intestinal epithelial cell‐specific AMPK knockout (AMPKαΔIEC KO) and AMPK floxed (AMPKαfl/fl) mice. 40kDa DSS was administered at 2.5% in drinking water ad libitum for 5 days followed by 3 days of water. Disease activity index was calculated from daily measures of body weight, stool consistency, and presence of hemaoccult. On the day of sacrifice mice were orally gavaged with 4kDa FITC‐dextran and blood was collected after 4 hours to determine intestinal permeability. Mice were sacrificed and intestinal tissues were flash frozen. Citrobacter rodentium infection was performed in mice housed under specific pathogen‐free (SPF) conditions following overnight treatment of 50ng/mL streptomycin. Mice were orally gavaged with ~108 CFU of C. rodentium (DBS100 streptomycin‐resistant strain). Fecal bacterial load was determined regularly until sacrifice on day 10 post‐infection. Colon and extra‐intestinal tissues (mesenteric lymph nodes, spleen, and liver) were excised to determine bacterial burden.

Results

AMPKαΔIEC KO mice did not exhibit increased susceptibility to 2.5% DSS compared to AMPKαfl/fl mice as determined by similar changes in body weight and disease activity index throughout the course of disease. In addition, there were no significant differences in colon weight or length after DSS (n = 4 – 15). AMPKαΔIEC KO mice do not appear to have significantly increased intestinal permeability after DSS treatment. To test if AMPK is important for responses to enteric infection, mice were infected with Citrobacter rodentium, a mouse model of enteropathogenic (EPEC) and enterohemorrhagic E. coli (EHEC) infection in humans. Infected mice had identical increases in fecal bacterial burden over time (~107 CFU/g, n = 3–6) and loss of AMPK did not affect disease progression. In addition, AMPK deficiency did not increase bacterial invasion of extra‐intestinal tissues (n = 3–4).

Conclusions

These data suggest that AMPK plays only a minor role in intestinal epithelial function and suggests that protection from colitis is mediated by AMPK‐independent pathways.

Support or Funding Information

NIH 2R01DK091281 (DFM)

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.