François Blachier

In this review, we present the main luminal fuels that are responsible for energy production in colonocytes, namely the bacterial metabolites short-chain fatty acids and lactate, which are produced from undigestible polysaccharides and proteins, and hydrogen sulfide that is mainly produced from undigested proteins. In addition to these luminal fuels, colonocytes can use glutamine, and to a lower extent glucose, as energy substrates provided by arterial capillaries. The effects of excessive concentrations of bacterial metabolites within the colonic luminal fluid (including butyrate, hydrogen sulfide, p-cresol, indole derivatives, ammonia, 4-hydroxyphenylacetic acid, and acetaldehyde) on the mitochondrial energy metabolism in colonic epithelial cells and the consequences of altered ATP production on the colonic epithelium renewal and barrier function are detailed, as well as consequences for water and electrolyte absorption. The relationships between modifications of these latter processes and development of colitis are then discussed. Finally, several mechanisms that are considered as adaptive against deleterious effects of bacterial metabolites on colonic epithelial cell energy metabolism are presented.