Carbon monoxide-bound hemoglobin vesicles ameliorate multiorgan injuries induced by severe acute pancreatitis in mice by their anti-inflammatory and antioxidant properties

Saori Nagao,1,2 Kazuaki Taguchi,3 Hiromi Sakai,4 Keishi Yamasaki,3,5 Hiroshi Watanabe,1,6 Masaki Otagiri,3,5 Toru Maruyama1,6 1Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, 2Research Fellow of Japan Society for the Promotion of Science, Tokyo, 3Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, 4Department of Chemistry, Nara Medical University, Kashihara, 5DDS Research Institute, Sojo University, 6Center for Clinical Pharmaceutical Sciences, School of Pharmacy, Kumamoto University, Kumamoto, Japan Abstract: Carbon monoxide (CO) has attracted attention as a possible therapeutic agent for affecting anti-inflammatory and antioxidant activities. Previously, CO-bound hemoglobin vesicle (CO-HbV) was developed as a nanotechnology-based CO donor, and its safety profile and therapeutic potential as a clinically applicable carrier of CO were examined in vitro and in vivo. In the present study, the therapeutic efficacy of CO-HbV against severe acute pancreatitis was examined with secondary distal organ-injured model mice that were fed with a choline-deficient ethionine-supplemented diet. A CO-HbV treatment significantly reduced the mortality of the acute pancreatitis model mice compared to saline and HbV. Biochemical and histological evaluations clearly showed that CO-HbV suppressed acute pancreatitis by inhibiting the production of systemic proinflammatory cytokines, neutrophil infiltration, and oxidative injuries in pancreatic tissue. Interestingly, CO-HbV also diminished the subsequent damage to distal organs including liver, kidneys, and lungs. This could be due to the suppression of neutrophil infiltration into tissues and the subsequently enhanced oxidative injuries. In contrast, O2-bound HbV, the inactive form of CO-HbV, was ineffective against both pancreatitis and distal organ injuries, confirming that CO was directly responsible for the protective effects of CO-HbV in acute pancreatitis. These findings suggest that CO-HbV has anti-inflammatory and antioxidant characteristics of CO and consequently exerts a superior protective effect against acute pancreatitis-induced multiorgan damage. Keywords: acute pancreatitis, carbon monoxide, CDE diet, liposome, oxidative stress, inflammatio