Gut Immunity – Homeostasis and Dysregulation in Sepsis

Abstract

The mucosal immune system plays a central role in the pathophysiology of health and disease. As the home to the largest population of lymphocytes in the body, the mucosal immune system closely communicates within other elements of the intestine, with constant cross talk with the gut microbiome and epithelial layer. Further, the gut's immune system plays a central role in communicating with remote organs. The mucosal immune system is critical in preventing autoimmunity, while simultaneously retaining the capacity to respond vigorously to mucosal invaders. This results in a state where the mucosal immune system not only can help restore homeostasis in critical illness but can also worsen inflammation and organ injury in sepsis. The purpose of this minireview is to provide an overview of mucosal immunity in health and in sepsis, with a focus on intraepithelial lymphocytes. Understanding the role of the mucosal immune system in both controlling and propagating sepsis is vital for future efforts designed to target it for therapeutic gain in the intensive care unit.