Effects of Bacterial Translocation and Autophagy on Acute Lung Injury Induced by Severe Acute Pancreatitis

Abstract

Aim. To reveal the role of bacterial translocation (BT) and autophagy in severe acute pancreatitis-induced acute lung injury (SAP-ALI). Methods. Rats were separated into a control (sham-operation) group (n=10) and a SAP group (n=30). Sodium taurocholate (5%) was retrogradely injected into the cholangiopancreatic duct to induce SAP-ALI in rats. Then, 16S rDNA sequencing was used to detect bacterial translocation (BT). Hematoxylin eosin staining (HE) was used to detect morphological changes to the pancreas, intestine, and lung. And lung tissue wet/dry weight ratio (W/D ratio) was used to assess the extent of pulmonary edema. The expressions of LC3II and Beclin1 proteins were analyzed by western blot and immunofluorescence. Glutathione peroxidase (GPx), malondialdehyde (MDA), and superoxide dismutase (SOD) were used to assess oxidative stress in lung tissue. Results. Levels of TNF-α, IL-6, lipase, and amylase in the SAP group were significantly higher than those in the control group (P<0.01). Histopathological score and W/D ratio of the lung in the SAP-BT(+) group were significantly higher than that in the SAP-BT(-) group (P<0.01). LC3II expression was higher in the SAP-BT(-) group than that in the SAP-BT(+) group (P<0.01). The results were consistent with those of LC3II immunofluorescence assay. The expression of Beclin1 was similar to that of LC3II (P<0.01). MDA content in the SAP-BT(+) group was significantly higher than that in the SAP-BT(-) group (P<0.01), whereas SOD and GPX activities were opposite (P<0.01). Conclusions. BT can aggravate SAP-ALI with the increasing oxidative stress level, which may be related to the decrease of autophagy level.