Nutrition and autophagy deficiency in critical illness.

PURPOSE OF REVIEW: Critical illness imposes a severe insult on the body, with various stressors triggering pronounced cell damage. This compromises cellular function, leading to a high risk of multiple organ failure. Autophagy can remove damaged molecules and organelles but appears insufficiently activated during critical illness. This review discusses insight into the role of autophagy in critical illness and the involvement of artificial feeding in insufficient autophagy activation in critical illness.

RECENT FINDINGS: Animal studies manipulating autophagy have shown its protective effects against kidney, lung, liver, and intestinal injury after several critical insults. Autophagy activation also protected peripheral, respiratory, and cardiac muscle function, despite aggravated muscle atrophy. Its role in acute brain injury is more equivocal. Animal and patient studies showed that artificial feeding suppressed autophagy activation in critical illness, particularly with high protein/amino acid doses. Feeding-suppressed autophagy may explain short and long-term harm by early enhanced calorie/protein feeding in large randomized controlled trials.

SUMMARY: Insufficient autophagy during critical illness is at least partly explained by feeding-induced suppression. This may explain why early enhanced nutrition failed to benefit critically ill patients or even induced harm. Safe, specific activation of autophagy avoiding prolonged starvation opens perspectives for improving outcomes of critical illness.