Niacin Pretreatment Attenuates Ischemia and Reperfusion of Pancreas-induced Acute Pancreatitis and Remote Lung Injury Through Suppressing Oxidative Stress and Inflammation and Activation of SIRT1.

BACKGROUND

Lung injury subsequent to pancreatic ischemia and reperfusion (PIR) due to shock, revascularization, and pancreas transplantation is a major clinical problem. In addition to proteases, massive production and release of reactive oxygen species (ROS) and induction of inflammatory cytokines have been implicated in remote lung injury. Niacin, also known as vitamin B, is both antioxidative and anti-inflammatory. In this study, we examined the protective effectiveness of niacin pretreatment against PIR-induced pancreatic and remote lung injury.

METHODS

Male Sprague-Dawley rats were divided into a sham-operated group, a PIR group, and a PIR group pretreated with niacin; the niacin (300 mg/kg per day) was given on 4 consecutive days before the study. Pancreatic ischemia was established by occluding both the gastroduodenal and splenic arteries for 120 minutes, followed by 240 minutes of reperfusion. Lung injury was assessed by pulmonary barrier function via pulmonary filtration coefficient, K, using an isolated-perfused rat lung preparation. Alveolar protein leakage was assessed by protein concentration in the bronchoalveolar lavage fluid (PCBAL). Lung water content was assessed by both wet-weight/dry-weight ratio (W/D) and lung-weight/body-weight ratio (LW/BW). Lung inflammation was evaluated by the lavage differential neutrophil cell count and tissue tumor necrosis-alpha (TNF-α) level. Oxidative stress was assessed by tissue malondialdehyde (MDA) level. Serum lactate dehydrogenase (LDH) and amylase were examined for lung and pancreas injury. We also evaluated lung tissue SIRT1 mRNA expression.

RESULTS

Compared with the sham group, the PIR group had increased serum amylase and LDH, and impaired the pulmonary barrier dysfunction with marked increases in K, PCBAL, W/D, and LW/BW, and augumented oxidative stress and inflammation with elevated tissue MDA and TNF-α and lavage neutrophil count, which correlated with decreased SIRT1 mRNA expression. Conversely, niacin pretreatment reduced pancreatic and remote lung injury and attenuated pulmonary oxidative stress and inflammation, and also protected against PIR-induced pulmonary barrier dysfunction while restoring SIRT1 mRNA expression.

CONCLUSION

Niacin pretreatment reduced PIR-induced pancreatic and lung injury and protected against pulmonary barrier function impairment, which was associated with niacin's antioxidative and anti-inflammatory activity and its capacity to increase SIRT1 mRNA expression.