HMGB1 and necrotizing enterocolitis: It has been shown that Claudin-3 is a potential diagnostic biomarker for intestinal permeability and it increases in the intestinal tissues of NEC rats (10, 14).HMGB-1 in the nucleus is actively secreted by intestinal epithelial cells or inflammatory cells stimulated by inflammatory response signals or released into the intestinal lumen by necrotic cells.