Figure 1.

Immune Manifestations in NEC. Schematic illustrating immune signaling involving toll-like receptor 4 (TRL4) in necrotizing enterocolitis (NEC) pathogenesis. The premature immune system leaves the neonate prone to infectious and inflammatory diseases such as NEC. Mediated by exaggerated TLR4 signaling on the intestinal epithelium, the onset of NEC leads to mobilization of an endogenous TLR4 ligand, high mobility group box 1 (HMGB1) from the intestine to the lungs and brain where TLR4 activation on the pulmonary epithelium and microglia respectively leads to phenomena such as neutrophil infiltration, reactive oxygen species (ROS) buildup, and other downstream effects that exacerbate pathology in the lungs, brain and other organ systems.