Objective: To observe the indexes of liver injury and the expression of inflammation-related factor interleukin-10 (IL-10) in rats with severe acute pancreatitis (SAP), and to discuss the correlation between the expression of IL-10 and the related factors of liver injury in SAP rats at different altitudes.
Methods: 280 male Wistar rats with SPF grade aged 5 to 6 months were divided into four groups according to random number table with 70 rats in each group, and the rats were placed in different altitudes such as Xi'an (at an altitude of 1 027 m), Xining (at an altitude of 2 260 m), Xinghai (at an altitude of 3 300 m) and Wenquan (at an altitude of 3 950 m). The rats in each altitude were randomly divided into sham operation group (Sham group, n = 10) and SAP 1, 6, 12, 24 hours groups (all n = 15). SAP rat model was reproduced by injecting sodium cholate into the posterior membrane of pancreas, and the rats of Sham group were only turned pancreas over several times after opening the abdomen and then closed the abdomen. The rats were sacrificed at the corresponding time points after model reproduction in SAP groups, and rats in Sham group were sacrificed at 6 hours after sham operation. At the same time, the abdominal aorta blood was harvested, and the contents of serum amylase (AMY), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined by automatic biochemical analyzer. Liver tissues were harvested, and the expression level of IL-10 was determined by immunohistochemistry. Pancreatic tissues were harvested, and hematoxylin-eosin (HE) staining was performed to observe the pathological changes under light microscopy. The correlations among the indicators were analyzed by Pearson correlation.
Results: At different altitudes, no significant abnormality was found in the pancreas of Sham group, but significant pathological changes were found in the pancreas of all SAP groups, mainly manifested as pancreatic acinar swelling, inflammatory cell infiltration, vascular congestion and hemorrhage, acinar cell degeneration and dissolution, changes in glandular lobule structure, peri-pancreatic fat necrosis, and continuous aggravation with the increasing of time and altitude. At the same altitude, the pancreatic pathology score, the serum AMY, ALT and AST levels, and the hepatic IL-10 expression were all significantly increased in all the SAP groups as compared with those in Sham group, and they were continuously increased with time. In Sham group, there was no statistically significant difference in pancreatic pathology score, AMY, ALT, AST, or IL-10 level among different altitudes. At the corresponding time point after model reproduction, the pancreatic pathology score, AMY, ALT, AST and IL-10 levels in the SAP groups were also shown a continuous rising tendency with altitude increase, and the differences in above parameters of SAP 24 hours group in Wenquan area were statistically significant as compared with those of Sham group [pathology score: 11.06±0.94 vs. 0.23±0.15, AMY (mmol/L): 2 706.6±208.3 vs. 336.5±94.3, ALT (U/L): 267.00±5.37 vs. 52.00±4.84, AST (U/L): 465.88±11.02 vs. 139.00±11.61, IL-10 (A value): 0.579±0.006 vs. 0.281±0.006, all P < 0.05]. It was shown by correlation analysis that IL-10 of SAP rats at different altitudes was positively correlated with pancreatic pathology score, AMY, ALT and AST, the correlation coefficient (r value) between IL-10 and the above indicators in the Wenquan area with the highest altitude was 0.959, 0.928, 0.977, 0.983, respectively (all P < 0.01).
Conclusions: The severity of SAP rats was positively correlated with altitude. IL-10 was involved in the pathological expression process of SAP liver damage, and its expression level was positively correlated with altitude and the degree of SAP liver damage.