Although high-mobility group box-1 (HMGB1) is related to the persistent intestinal inflammation in the development of necrotizing enterocolitis (NEC), the role of HMGB1 in the regulation of the intestinal microcirculation in NEC is not well understood. Therefore, we investigated the mechanism(s) by which HMGB1 regulates the generation of the following vasodilatory signals during the development of NEC: endothelial nitric oxide synthase (eNOS) and nitric oxide (NO). Experimental NEC was induced in full-term C57BL/6 mouse pups through the formula gavage and hypoxia technique. The blockade of HMGB1 was achieved with a subcutaneous injection of anti-HMGB1 antibody. Intestinal tissues and blood samples were collected at predetermined time points for the assessment of intestinal microcirculation, lipid peroxidation levels, and evaluation of eNOS activation. We found elevations in HMGB1 expression as early as 12 h after induction of NEC stress, which preceded intestinal injury. Treatment of mouse pups with HMGB1 neutralizing antibody attenuated the intestinal microvascular features and symptoms of NEC, but this improvement was not found in the eNOS knockout mice, suggesting that HMGB1 inhibition increased intestinal microcirculatory perfusion in an eNOS-dependent manner. Moreover, HMGB1 inhibition rescued NO production and eliminated O2•- production in experimental NEC mice through eNOS activation. These data indicate that excessive HMGB1 signaling is associated with the pathogenesis of NEC, suggesting that HMGB1 inhibition might be a promising strategy for NEC treatment.
Keywords: endothelial nitric oxide synthase; high-mobility group box-1; intestinal microcirculation; necrotizing enterocolitis.