Alpha‐ketoglutarate promotes goblet cell differentiation and alters metabolome in a mouse model of colitis

Abstract

BackgroundAlpha‐ketoglutarate (aKG) is a key intermediate of the tricarboxylic acid (TCA) cycle. Previously, we demonstrated that aKG supplementation mitigates inflammation, enhances epithelial barrier integrity, and promotes oxidative phosphorylation in dextran sulfate sodium (DSS)‐induced colitis of mice. Intestinal epithelial homeostasis is regulated by cell energetics and metabolites from the microbiome. Given the importance of the mucosal layer in maintaining gut epithelial barrier function and microbiome composition, we hypothesized that dietary aKG facilitates the differentiation of secretory lineage epithelial cells and improves the gut metabolome.MethodsC57BL/6 male mice received drinking water with or without 1% aKG for three weeks, when mice were subjected to DSS induction for 7 days followed by 7 days recovery. The GC‐MS analysis was used to profile the cecal metabolomic changes due to aKG supplementation. In addition, colonic tissues were sampled for both biological and histochemical analyses.ResultsGC‐MS metabolomics revealed separation of the cecal metabolites between control (CON) and aKG supplemented (aKG) mice. In total, the contents of 40 metabolites were found to be different between CON and aKG groups. These metabolites include amino acids, fatty acids, and the B vitamin, niacin, succinic acid (butanedioic acid), the conjugate acid of succinate. Putrescine, a polyamine produced by intestinal microbiota and methysuccinic acid were among the metabolites with the largest fold change increased by dietary aKG. Amino acids including essential amino acids and those involved in the TCA cycle such as threonine and aspartic acid were elevated in the aKG group, of which, glycine displayed a 10‐fold increase. On the other hand, ornithine, an intermediate of the urea cycle, and amide products such as oleamide and urea were significantly decreased in aKG group. Pathway analysis revealed that the urea cycle, along with and arginine and proline metabolism and glutathione metabolism were altered due to aKG supplementation. Furthermore, aKG supplementation increased goblet cells based on Alcian blue staining, associated with increased mRNA expression of Mucin 2 and goblet cell differentiation markers Trefoil factor 3 and Krüppel‐like factor 4.ConclusionTogether, dietary aKG enhances intestinal epithelial differentiation to favor goblet cell differentiation, which correlates with improvement in metabolome.