Treatment with bindarit, a blocker of MCP-1 synthesis, protects mice against acute pancreatitis

Overexpression of redox-active protein thioredoxin-1 prevents development of chronic pancreatitis in mice

Chronic pancreatitis (CP) is considered to result from repetitive pancreatic injury, and sustained production of various proinflammatory cytokines and chemokines are closely involved in its pathogenesis. Monocyte chemoattractant protein 1 (MCP-1), a member of the CC chemokine family, is believed to contribute to the progression of CP through monocyte/macrophage recruitment. This study aimed to clarify the protective role of thioredoxin-1 (TRX-1), a redox-regulating protein with antioxidative activity, in MCP-1 production and pancreatic fibrosis using a CP model in transgenic mice overexpressing TRX-1 (TRX-1-TG mice) and wildtype C57BL/6 mice. Experimental CP was induced by repeated administration of cerulein and lipopolysaccharide for 6 weeks. In TRX-1-TG mice, pancreatic atrophy was ameliorated, and histologically detectable inflammatory cell infiltration, glandular atrophy, and pseudotubular complex formation were suppressed. Overexpression of TRX-1 also attenuated pancreatic fibrosis and suppressed the activation of pancreatic stellate cells. Serum levels of MCP-1 and pancreatic expression of transforming growth factor-beta, platelet-derived growth factor, and MCP-1 were reduced in TRX-1-TG mice compared with levels in wild-type mice. Overexpression of TRX-1 also reduced H(2)O(2)-induced MCP-1 production in isolated pancreatic acinar cells. These results indicate that TRX-1 can potentially attenuate pancreatic fibrosis via the suppression of oxidative stress and MCP-1-mediated chronic inflammation.

Acute pancreatitis

PURPOSE OF REVIEW

This review presents advances in our understanding of the pathobiologic responses of acute pancreatitis from studies using animal models of experimental pancreatitis as well as results of key clinical trials and observations.

RECENT FINDINGS

The reports during the past year show significant advances in our understanding of the pathobiology of acute pancreatitis. In particular, there are findings presented that are relevant to our further understanding of pancreatic intracellular digestive enzyme activation; the pancreatic inflammatory response; and cell death responses such as necrosis as apoptosis. Other reports add to understanding of the control of microcirculatory disturbances in acute pancreatitis, and of the role of the pancreatic neural system in regulating the microcirculation as well as the pain associated with the disorder. Finally, there are clinical trials showing benefits of enteral feeding on outcome of acute pancreatitis as well as the finding that diclofenac prevents endoscopic retrograde cholangiopancreatography-induced pancreatitis.

SUMMARY

Our understanding of the mechanistic processes that mediate the pathobiologic responses of pancreatitis is rapidly evolving. In addition, we now have initial evidence for potential treatment strategies for this disorder. Testing treatment strategies will lead to improved therapies and outcomes for patients with acute pancreatitis.

Bile-pancreatic juice exclusion promotes Akt/NF-kappaB activation and chemokine production in ligation-induced acute pancreatitis

Using a unique surgical model (the donor rat model), we showed previously that duodenal replacement of bile-pancreatic juice, obtained fresh from a donor rat, ameliorates ligation-induced acute pancreatitis. We hypothesize that bile-pancreatic juice exclusion from gut exacerbates Akt/nuclear factor-kappaB (NF-kappaB) pathway activation and induces chemokine production in ligation-induced acute pancreatitis. We compared rats with bile-pancreatic duct ligation to those with duodenal bile-pancreatic juice replacement fresh from a donor rat beginning immediately before duct ligation. Sham control rats had ducts dissected but not ligated. Rats were killed 1 or 3 hours after operation (n = 7/group). Akt activation (immunoblotting, immune-complex kinase assay, and ELISA), inhibitory protein I-kappaB (IkappaB) activation (immunoblotting), and production of chemokines MCP-1 and RANTES (ELISA) were measured in pancreatic homogenates. NF-kappaB was quantitated in nuclear fractions using electrophoretic mobility shift assay. Duct ligation produced significant increases in pancreatic Akt, IkappaB, and NF-kappaB activation and production of MCP-1 and RANTES. Activation of the Akt/NF-kappaB pathway and increased MCP-1 and RANTES production in response to duct ligation were significantly reduced by bile-pancreatic juice replacement (ANOVA, P < 0.05). Bile-pancreatic juice exclusion stimulates Akt/NF-kappaB pathway activation and increases chemokine production in ligation-induced acute pancreatitis.

Protein kinase C modulates the pulmonary inflammatory response in acute pancreatitis

The present study aims at evaluating the role of protein kinase C (PKC) in the development of acute lung injury, production of inflammatory mediators and expression of adhesion molecules on leukocytes after induction of acute pancreatitis (AP). AP was induced by the intraductal infusion of 5% sodium taurodeoxycholate in the rat. The animals had the PKC inhibitor polymyxin B administered intraperitoneally 30min prior to induction of AP. Levels of protein content, protease activity, cytokines and chemokines in bronchoalveolar lavage fluid (BALF) were assessed 1 and 6h after AP induction. Adhesion molecule expression on leukocytes were measured by flowcytometry. Pretreatment with polymyxin B prevented against acute pancreatitis-induced lung injury and the otherwise occurring increases in TNF-alpha, IL-1beta, MCP-1 and IL-10, as well as against the decreases in IL-2, IFNgamma and TIMP-1, decreased protease activity and down-regulation of CD31, CD54 and CD62L on recruited neutrophils and macrophages in BALF. The results indicate that the leukocyte response in acute pancreatitis vary depending on leukocyte subpopulation. It seems that activation of the PKC signalling pathway may play an important role in pancreatitis-associated lung injury.

Protective roles of redox-active protein thioredoxin-1 for severe acute pancreatitis

Severe acute pancreatitis is a disease with high mortality, and infiltration of inflammatory cells and reactive oxygen species have a crucial role in the pathophysiology of this disease. Thioredoxin-1 (TRX-1) is an endogenous redox-active multifunctional protein with antioxidant and anti-inflammatory effects. TRX-1 is induced in various inflammatory conditions and shows cytoprotective effects. The aim of the present study was to clarify the protective roles of TRX-1 in the host defense mechanism against severe acute pancreatitis. Experimental acute pancreatitis was induced by intraperitoneal administration of cerulein, a CCK analog, and aggravated by lipopolysaccharide injection in transgenic mice overexpressing human TRX-1 (hTRX-1) and control C57BL/6 mice. Transgenic overexpression of hTRX-1 strikingly attenuated the severity of experimental acute pancreatitis. TRX-1 overexpression suppressed neutrophil infiltration as determined by myeloperoxidase activity, oxidative stress as determined by malondialdehyde concentration, and cytoplasmic degradation of inhibitor of kappaB-alpha, thereby suppressing proinflammatory cytokines, tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6; a neutrophil chemoattractant, keratinocyte-derived chemokine; and inducible nitric oxide synthase in the pancreas. Administration of recombinant hTRX-1 also suppressed neutrophil infiltration, reduced the inflammation of the pancreas and the lung, and improved the mortality rate. The present study suggests that TRX-1 has potent antioxidant and anti-inflammatory actions in experimental acute pancreatitis and might be a new therapeutic strategy to improve the prognosis of severe acute pancreatitis.