Acute pancreatitis in aging animals:Loss of pancreatitis-associated protein protection?

AIM:To investigate the effect of age on severity of acute pancreatitis(AP) using biochemical markers,histology and expression of the protective pancreatitisassociated proteins(PAPs).METHODS:AP was induced via intraductal injection of 4% sodium taurocholate in young and old rats.Sera and pancreata were assayed at 24 h for the parameters listed above;we also employed a novel molecular technique to assess bacterial infiltration using polymerase chain reaction to measure bacterial genomic ribosomal RNA.RESULTS:At 24 h after induction of AP,the pancreata of older animals had less edema(mean ± SE histologic score of young vs old:3.11 ± 0.16 vs 2.50 ±-0.11,P < 0.05),decreased local inflammatory response(histologic score of stromal infiltrate:3.11 ± 0.27 vs 2.00 ± 0.17,P < 0.05) and increased bacterial infiltration(174% ± 52% increase from sham vs 377% ± 4%,P < 0.05).A decreased expression of PAP1 and PAP2 was demonstrated by Western blotting analysis and immunohistochemical staining.There were no differences in serum amylase and lipase activity,or tissue myeloperoxidase or monocyte chemotactic protein-1 levels.However,in the most-aged group,serum C-reactive protein levels were higher(young vs old:0.249 ± 0.04 mg/dL vs 2.45 ± 0.68 mg/dL,P < 0.05).CONCLUSION:In older animals,there is depressed PAP expression related to a blunted inflammatory response in AP which is associated with worsened bacterial infiltration and higher C-reactive protein level;this may explain the more aggressive clinical course.