ABSTRACT
BACKGROUND & AIMS: Heat shock protein (Hsp) 27 regulates actin cytoskeletal dynamics, and overexpression of Hsp27 in fibroblasts protects against stress in a phosphorylation-dependent manner. Induction of Hsps occurs in acute pancreatitis, but Hsp27 has not been ascribed a specific role. To examine whether Hsp27 would ameliorate acute pancreatitis, we generated transgenic mice overexpressing human Hsp27 (huHsp27) or Hsp27 with the phosphorylatable residues Ser(15,78,82) mutated to aspartic acid (huHsp27-3D) to mimic phosphorylation or to alanine (huHsp27-3A), which is nonphosphorylatable. METHODS: huHsp27 was expressed at high levels in the exocrine pancreas by use of a cytomegalovirus promoter. Protein expression was analyzed by Western blotting and immunofluorescence. Acute pancreatitis was induced with 6 or 12 hourly cerulein injections (50 microg/kg intraperitoneally) and its severity assessed by measuring serum amylase and lipase levels, pancreatic trypsin activity, edema, and morphologic changes by quantitative scoring of multiple histologic sections and visualization of filamentous actin. Systemic inflammatory effects were monitored by measuring lung myeloperoxidase activity (a marker of neutrophil infiltration). RESULTS: huHsp27 protein was overexpressed in the pancreas and localized to pancreatic acini. Acute pancreatitis was ameliorated by overexpression of huHsp27 and the huHsp27-3D mutant, which were associated with suppression of pancreatic trypsin activity and acinar cell injury and preservation of the actin cytoskeleton. In contrast, these changes were unaffected by overexpression of the nonphosphorylatable huHsp27-3A mutant. CONCLUSIONS: Pancreatic overexpression of huHsp27 protects against cerulein-induced acute pancreatitis in a specific phosphorylation-dependent manner and is associated with preservation of the actin cytoskeleton.
Subject(s)
Ceruletide/adverse effects , Gastrointestinal Agents/adverse effects , Heat-Shock Proteins/biosynthesis , Neoplasm Proteins/biosynthesis , Pancreatitis/immunology , Actins/drug effects , Actins/immunology , Acute Disease , Animals , Cytoskeleton/drug effects , Cytoskeleton/immunology , Female , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Models, Animal , Molecular Chaperones , Pancreatitis/chemically induced , Phosphorylation/drug effects , Severity of Illness IndexABSTRACT
BACKGROUND: Evidence indicates that hyperthermia preconditioning (HP) can be protective in kidney transplantation, possibly through increased heat shock protein (HSP) expression. A detailed study about individual HSPs and functional preservation is lacking, however. Therefore, we studied the effects of HP on kidney graft survival, function and HSP expression. METHODS: Male Lewis rats were or were not subjected to whole-body hyperthermia 24 h prior to kidney procurement. Kidneys were stored in UW solution at 4 degrees C for 32, 40 or 45 h. Recipient kidneys were both removed and single isografts transplanted orthotopically. RESULTS: HP strongly induced HSP72 and HSP32 expression. Following 32-hour cold ischemia, most animals survived even without prior HP. However, HP strongly reduced functional impairment induced by cold ischemia. Following 40-hour cold ischemia, kidneys from donors without HP did not recover function and all animals died within 3 days. In contrast, HP-exposed kidneys tolerated 40-hour storage significantly better, with 44% of rats surviving until sacrifice on day 7. In these animals, renal function was still better compared to animals with 32-hour-stored kidneys without HP. Histological alterations were also diminished following HP. CONCLUSION: Our data show that HP induces renal HSP72 and, for the first time, HSP32. HP increases survival following transplantation and acts by improving several parameters of kidney function including proteinuria, volume output and creatinine clearance.
Subject(s)
Cold Temperature , Heat-Shock Proteins/metabolism , Hot Temperature , Ischemic Preconditioning , Kidney Transplantation , Kidney/metabolism , Organ Preservation , Animals , Graft Survival , Kidney/blood supply , Kidney/cytology , Male , Rats , Survival Rate , Time FactorsABSTRACT
INTRODUCTION: Calpains, cytosolic Ca(2+)-dependent cysteine proteases, are expressed in a variety of mammalian cells and have been found to participate in stimulus-secretion coupling in platelets and alveolar cells. AIMS: In pancreatic acinar cells, expression of calpains and their role in the secretory process have not yet been elucidated. Both subjects, therefore, were examined in the current study. METHODOLOGY: mu-calpain and m-calpain were detected immunochemically. Calpain activation was measured by fluorescence spectrophotometry and single-cell fluorometry using Suc-Leu-Leu-Val-Tyr-AMC as substrate. Amylase secretion and cell damage, characterized by lactate dehydrogenase release, were measured by colorimetric assays. RESULTS: Immunochemistry revealed cytoplasmic localization of both calpain isoforms. Immediately after increasing the cytosolic Ca(2+) concentration with ionomycin, a marked dose-dependent protease activation and cellular damage were observed. Inhibition of ionomycin-mediated enzyme activation through preincubation of cells with Ca(2+)-free medium, BAPTA-AM, or Z-Leu-Leu-Tyr-CHN(2) significantly reduced cell injury. Cholecystokinin (100 pM) also induced proteolytic activity, preceding cholecystokinin-stimulated amylase secretion. Protease activity and amylase release were significantly inhibited by Z-Leu-Leu-Tyr-CHN(2 ) retreatment. CONCLUSION: Calpains are expressed in pancreatic acinar cells and may participate in stimulus-secretion coupling. In addition, our study indicates that pathologic calpain activation may contribute to Ca(2+)-mediated acinar cell damage.
