Role of anaerobic bacteria in the metabolic welfare of the colonic mucosa in man.

TLDR

The study hypothesizes that anaerobic bacterial fatty acids, particularly n‑butyrate, are a major energy source for colonic mucosa, especially in the distal colon. Colonocyte suspensions from seven ascending and seven descending colon specimens were incubated with n‑butyrate, glucose, and glutamine to measure oxygen consumption. Oxygen consumption was dominated by n‑butyrate (73–75%) but fell to 59–72% when 10 mM glucose was added, while glucose oxidation comprised 85% of respiration in the ascending colon and 30% in the descending colon, dropping to 41% and 16% with 10 mM n‑butyrate, and aerobic glycolysis was noted in both segments.

Abstract

Suspensions of isolated epithelial cells (colonocytes) from the human colon were used to assess utilisation of respiratory fuels which are normally available to the colonic mucosa in vivo. Cells were prepared from operative specimens of the ascending colon (seven) and descending colon (seven). The fuels that were used were the short chain fatty acid n-butyrate, produced only by anaerobic bacteria in the colonic lumen, together with glucose and glutamine, normally present in the circulation. The percentage oxygen consumption attributable to n-butyrate, when this was the only substrate, was 73% in the ascending colon and 75% in the descending colon. In the presence of 10 mM glucose these proportions changed to 59% and 72%. Aerobic glycolysis was observed in both the ascending and descending colon. Glucose oxidation accounted for 85% of the oxygen consumption in the ascending colon and 30% in the descending colon. In the presence of 10 mM n-butyrate these proportions decreased to 41% in the ascending colon and 16% in the descending colon. Based on the assumption that events in the isolated colonocytes reflect utilization of fuels in vivo, the hypothesis is put forward that fatty acids of anaerobic bacteria are a major source of energy for the colonic mucosa, particularly of the distal colon.