Therapeutic Effects of Hyaluronic Acid in Peritonitis-Induced Sepsis in Mice.

Intra-abdominal infection is the second most common cause of sepsis, and the mortality rate from abdominal sepsis remains high. High molecular weight (HMW) hyaluronic acid (HA) has been studied in sterile injury models as an anti-inflammatory and anti-permeability agent. This study evaluated the therapeutic effects of intraperitoneal HMW HA administration in mice with peritonitis-induced sepsis. Sepsis was induced in C57BL/6 mice by cecal ligation and puncture (CLP), followed 4 h later by an intraperitoneal injection of HMW HA (20 mg/kg) solution or phosphate buffered saline (PBS). Survival, physiological data, organ injury, bacterial burden, and inflammatory cytokine levels were assessed in the CLP mice. To assess the effect of HA on macrophage phagocytosis activity, RAW264.7 cells, primed with lipopolysaccharide, were exposed with either PBS or HMW HA (500 μg/mL) prior to exposure to 10 CFU of E coli bacteria. HMW HA instillation significantly improved blood oxygenation, lung histology, and survival in CLP mice. Inflammatory cytokine levels in the plasma and bacterial burdens in the lung and spleen were significantly decreased by HA administration at 24 h after CLP. At 6 h after CLP, HA significantly decreased bacterial burden in the peritoneal lavage fluid. HMW HA administration significantly increased E coli bacterial phagocytosis by RAW264.7 cells in part through increased phosphorylation of ezrin/radixin/moesin, a known downstream target of CD44 (a HA receptor); ezrin inhibition abolished the enhanced phagocytosis by RAW264.7 cells induced by HA. Intraperitoneal administration of HMW HA had therapeutic effects against CLP-induced sepsis in terms of suppressing inflammation and increasing antimicrobial activity.