Effects of synthetic serine protease inhibitors on proliferation and collagen synthesis of human pancreatic periacinar fibroblast-like cells

A New Insight into Chronic Pancreatitis

Chronic pancreatitis (CP) is a pancreatic disease with poor prognosis characterized clinically by abdominal pain, morphologically by pancreatic stones/calcification, duct dilatation and atrophy, and functionally by pancreatic exocrine and endocrine insufficiency. CP is also known as a risk factor for the development of pancreatic cancer. CP has long been understood based on a fixed disease concept deduced from the clinical and morphological features of the end-stage disease. However, identification of causal genes for hereditary pancreatitis and success in the isolation and culture of pancreatic stellate cells have advanced the understanding of the underlying pathological mechanisms, the early-stage pathophysiology, and the mechanisms behind pancreatic fibrosis. These advances have led to moves aimed at improving patient prognosis through prevention of disease progression by early diagnosis and early therapeutic intervention. The strategy for preventing disease progression has included a proposal for diagnostic criteria for early CP and introduction of a new definition of CP in consideration of the pathological mechanisms. Our group has been committed deeply to these studies and has provided a large amount of information to the world.

Pancreatic stellate cell: Pandora's box for pancreatic disease biology

Pancreatic stellate cells (PSCs) were identified in the early 1980s, but received much attention after 1998 when the methods to isolate and culture them from murine and human sources were developed. PSCs contribute to a small proportion of all pancreatic cells under physiological condition, but are essential for maintaining the normal pancreatic architecture. Quiescent PSCs are characterized by the presence of vitamin A laden lipid droplets. Upon PSC activation, these perinuclear lipid droplets disappear from the cytosol, attain a myofibroblast like phenotype and expresses the activation marker, alpha smooth muscle actin. PSCs maintain their activated phenotype via an autocrine loop involving different cytokines and contribute to progressive fibrosis in chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC). Several pathways (e.g., JAK-STAT, Smad, Wnt signaling, Hedgehog etc.), transcription factors and miRNAs have been implicated in the inflammatory and profibrogenic function of PSCs. The role of PSCs goes much beyond fibrosis/desmoplasia in PDAC. It is now shown that PSCs are involved in significant crosstalk between the pancreatic cancer cells and the cancer stroma. These interactions result in tumour progression, metastasis, tumour hypoxia, immune evasion and drug resistance. This is the rationale for therapeutic preclinical and clinical trials that have targeted PSCs and the cancer stroma.

Effect of antioxidant supplementation on surrogate markers of fibrosis in chronic pancreatitis: a randomized, placebo-controlled trial

OBJECTIVES

This study aimed to determine the effect of antioxidant (AO) supplementation on surrogate markers of fibrosis in patients with chronic pancreatitis (CP).

METHODS

In a randomized, placebo (PL)-controlled trial, patients with CP were randomized to groups that were given PL or AO for 3 months. Outcome measures were change in serum levels of transforming growth factor β1 and platelet-derived growth factor AA (PDGF-AA) (primary outcome) as well as blood markers of oxidative stress (thiobarbituric acid-reactive substances) and AO status (ferric-reducing ability of plasma) (secondary outcome). Pain relief and analgesic requirement was also recorded.

RESULTS

Patients (n = 61; mean [SD] age, 35.2 [10.0]; male patients, 43) were assigned to AO (n = 31) and PL (n = 30) groups. The median (range) percent reduction from baseline to 3 months in levels of PDGF-AA (17.1% [-25.3% to 88.7%] vs 2.8% [-243.1% to 30.2%]; P = 0.001), transforming growth factor β1 (P = 0.573), and thiobarbituric acid-reactive substances (P = 0.207) as well as percent increment from baseline to 3 months in ferric-reducing ability of plasma (P = 0.003) were higher in the AO group compared with the PL group. Proportion of patients who had both reduced PDGF-AA and reduced pain was greater in AO as compared with PL group (17/31 vs 9/30, P = 0.05)

CONCLUSIONS

Reduction in markers of fibrosis (PDGF-AA) translated into clinical outcome (reduction in pain and analgesic requirements) in those supplemented with AOs in CP (trial registration, CTRI/2011/05/001747).

Increased serum chemerin concentration in patients with chronic pancreatitis

BACKGROUND

Chemerin is a potent chemoattractant for chemokine-like receptor 1 expressing cells and is involved in inflammatory and immune processes that play an important role in chronic pancreatitis.

AIM

To test the hypothesis that serum chemerin concentration may be affected in chronic pancreatitis patients and that chemerin can influence the course of chronic pancreatitis by increasing profibrotic cytokine production.

METHODS

Serum concentrations of chemerin and the major cytokines involved in pancreatic fibrosis such as platelet-derived growth factor BB and transforming growth factor β-1 were determined by ELISA in samples from 40 nondiabetic and 28 diabetic male patients with chronic pancreatitis of alcoholic origin and 40 age-matched healthy controls.

RESULTS

Serum concentrations of chemerin were increased both in nondiabetic and diabetic chronic pancreatitis patients compared to controls. Moreover, in chronic pancreatitis patients a positive correlation was found between serum chemerin and platelet-derived growth factor BB as well as transforming growth factor β-1 concentrations.

CONCLUSIONS

The results indicate for the first time that: (a) chronic pancreatitis in humans is associated with an increased serum chemerin concentration and (b) serum chemerin concentration correlates with serum concentrations of the major profibrotic cytokines. Elevated level of chemerin, by stimulating macrophage infiltration of the pancreas, might lead to overproduction of platelet-derived growth factor BB and transforming growth factor β-1 and, consequently, to pancreatic fibrosis.

Coordinated increase in serum platelet-derived growth factor-BB and transforming growth factor-β1 in patients with chronic pancreatitis

BACKGROUND

In vitro studies suggest that platelet-derived growth factor-BB (PDGF-BB) and transforming growth factor-β1 (TGF-β1) play an important role in pancreatic fibrosis. The aim of this study was to evaluate serum PDGF-BB and TGF-β1 concentrations in patients with chronic pancreatitis (CP).

METHODS

Forty male patients with a history of alcoholic CP and 35 age-matched healthy subjects were examined. Serum concentrations of PDGF-BB, TGF-β1, laminin and hyaluronic acid were determined by ELISA assay. Additionally, we determined serum concentrations of PDGF-BB and TGF-β1 in patients with functional dyspepsia, ulcerative colitis and Crohn's disease.

RESULTS

Patients with advanced CP had significantly higher serum PDGF-BB and TGF-β1 concentrations compared to control subjects. A strong positive correlation between serum PDGF-BB and TGF-β1 concentrations was found in patients with CP. Serum laminin and hyaluronic acid were also elevated in patients with CP. No increase in serum PDGF-BB and TGF-β1 concentrations was found in patients with functional dyspepsia, ulcerative colitis or Crohn's disease.

CONCLUSION

The obtained results indicate for the first time that serum levels of PDGF-BB are elevated in patients with CP. However, ROC curve analysis suggests that PDGF-BB is not superior to laminin as a potential marker of advanced CP.

Role of stellate cells in pancreatic fibrogenesis associated with acute and chronic pancreatitis

Pancreas fibrosis is the result of a dynamic cascade of mechanisms beginning with acinar cell (AC) injury and necrosis and followed by inflammation, activation of macrophages, aggregation of platelets, release of growth factors and reactive oxygen species (ROS), activation of pancreatic stellate cells (PSC), stimulated synthesis of extracellular matrix and reduced matrix degradation. The result is a net matrix accumulation. Numerous in vivo and in vitro studies have provided strong evidence of a central role for PSC in fibrogenesis associated with acute and chronic pancreatitis. The PSC share homologies with hepatic stellate cells (HSC). In normal pancreas, the fat-storing phenotype of PSC is found in low numbers (approx. 4% of the cells) in the periacinar and interlobular space. Similar to the stellate cell-activating mechanisms in the liver, in pancreas injury PSC change their phenotype from the fat-storing to a highly active matrix-producing cell type (activated PSC). The induction of the activated phenotype of PSC has been shown to involve a number of diverse extra- and intracellular effector molecules, including inflammatory cytokines, growth factors, ethanol, acetaldehyde, and oxidative stress.

Camostat, an oral trypsin inhibitor, reduces pancreatic fibrosis induced by repeated administration of a superoxide dismutase inhibitor in rats

BACKGROUND AND AIM

An oral trypsin inhibitor, camostat (CM), has a beneficial effect on chronic pancreatitis, but its mechanism is not yet fully understood. Recently, pancreatic stellate cells (PSC) have been reported to play an essential role in pancreatic fibrosis. An experimental model of pancreatic fibrosis induced by a superoxide dismutase (SOD) inhibitor (diethyldithiocarbamate [DDC]) was developed in rats. Thus, the effect of an oral trypsin inhibitor on pancreatic fibrosis and PSC was investigated.

METHODS

Pancreatic fibrosis was induced in rats using DDC (DDC rats). DDC + CM rats were administered DDC, and subsequently were fed a diet containing CM. Immunohistochemistry of the pancreas was performed with monoclonal anti-alpha-smooth muscle actin (alpha-SMA) antibody and anti-desmin antibody.

RESULTS

The DDC rats showed a significant increase in alpha-SMA-positive cells or desmin-positive cells compared with control rats. These significant increases in the fibrotic area improved after treatment with CM. The level of prolyl hydroxylase in the pancreas, which significantly increased as a result of DDC, decreased after treatment with CM.

CONCLUSION

Camostat has a beneficial effect on pancreatic fibrosis induced by the administration of a SOD inhibitor, which inhibits the proliferation and activation of PSC.

Synthetic protease inhibitor camostat prevents and reverses dyslipidemia, insulin secretory defects, and histological abnormalities of the pancreas in genetically obese and diabetic rats

BACKGROUND

Otsuka Long-Evans Tokushima Fatty (OLETF) rat, a model of type 2 diabetes, lacks the expression of cholecystokinin-1 receptor mRNA and exhibits inflammation and degeneration of the pancreas and eventually develops insulinopenic diabetes. Protease inhibitors are known to modulate inflammatory response and fibrosis as well as inhibit proteases activity.

AIM

To examine the effects of long-term treatment with camostat, a synthetic protease inhibitor, on metabolic and histopathological changes in the islets of OLETF rats.

METHOD

OLETF rats were fed either camostat-containing food (200 mg/100 g) from 12 or 28 weeks of age to 72 weeks of age, or fed standard rat diet.

RESULTS

Camostat-fed rats gained less weight or lost weight, although they consumed more food than the control rat when food intake was adjusted for body weight. Camostat reduced visceral adipose depots and fasting serum concentrations of triglyceride, free fatty acids, cholesterol, glucose, and insulin. Pancreatic insulin content in camostat-treated rats was significantly higher than in control rats. Immunohistochemistry revealed marked suppression of expressions of tumor necrosis factor alpha , interleukin 1 beta , interleukin 6, and alpha-smooth muscle actin in the islets of camostat-treated rats, compared with control rats. Histologically, disruption of the islets and pancreatic fibrosis were noted in control rats but not in camostat-fed rats.

CONCLUSION

Our findings suggest that camostat prevents and reverses obesity, hyperinsulinemia, hyperglycemia, and hyperlipidemia and markedly inhibits inflammation, fibrosis, and disruption of the islets in the genetically obese diabetic OLETF rats.

Pro-inflammatory cytokine-induced matrix metalloproteinase-1 (MMP-1) secretion in human pancreatic periacinar myofibroblasts

Matrix metalloproteinases (MMPs) are the proteases involved in the degradation of the extracellular matrix. MMP-1 is thought to be one of the key enzymes in fibrolysis, a process closely related to tissue remodeling. In the present study, we investigated MMP-1 secretion from human pancreatic periacinar myofibroblasts in response to pro-inflammatory cytokines IL-1beta and TNF-alpha. We also attempted to clarify the intracellular signaling pathways mediating the cytokine-induced MMP-1 secretion. MMP-1 secretion was measured by an enzyme-linked immunosorbent assay. MMP-1 molecules were analyzed by Western blotting. MMP-1 mRNA expression was evaluated by Northern blotting. IL-1l and TNF-alpha stimulated the MMP-1 secretion in a dose- and time-dependent manner. Ninety percent of MMP-1 was secreted as inactive form (pro-MMP-1). The effects of IL-1beta and TNF-alpha were significantly inhibited by PD98059 MEK/ERK inhibitor). In contrast, SB203580 (p38 MAPK inhibitor), GF109203X (PKC inhibitor), and PDTC (NF-kappaB inhibitor) did not alter the MMP-1 secretion induced by IL-1beta and TNF-alpha. These effects were also observed at them RNA level. In conclusion, in human pancreatic periacinar myofibroblasts, MMP-1 secretion was regulated by the pro-inflammatory cytokines via the MEK/ERK cascade. Thus, human pancreatic periacinar myofibroblasts may play an important role in the remodeling of damaged pancreatic tissue in chronic pancreatitis via MMP-1 secretion.