Stimulation of stellate cells by injured acinar cells: a model of acute pancreatitis induced by alcohol and fat (VLDL)

Abstract

MG. Stimulation of stellate cells by injured acinar cells: a model of acute pancreatitis induced by alcohol and fat (VLDL). Am J Physiol Gastrointest Liver Physiol 297: G1163-G1171, 2009. First published September 24, 2009 doi:10.1152/ajpgi.90468.2008.-Mechanisms leading to acute pancreatitis after a fat-enriched meal combined with excess alcohol are incompletely understood. We have studied the effects of alcohol and fat (VLDL) on pancreatic acinar cell (PAC) function, oxidative stress, and repair mechanisms by pancreatic stellate cells (PSC) leading to fibrogenesis. To do so, PAC (rat) were isolated and cultured up to 24 h. Ethanol and/or VLDL were added to PAC. We measured PAC function (amylase, lipase), injury (lactic dehydrogenase), apoptosis (TUNEL, Apo2.7, annexin V binding), oxidative stress, and lipid peroxidation (conjugated dienes, malondialdehyde, chemoluminescence); we also measured PSC proliferation (bromodeoxyuridine incorporation), matrix synthesis (immunofluorescence of collagens and fibronectin, fibronectin immunoassay), and fatty acids in PAC supernatants (gas chromatography). Within 6 h, cultured PAC degraded and hydrolyzed VLDL completely. VLDL alone (50 g/ml) and in combination with alcohol (0.2, 0.5, and 1% vol/vol) induced PAC injury (LDL, amylase, and lipase release) within 2 h through generation of oxidative stress. Depending on the dose of VLDL and alcohol, apoptosis and/or necrosis were induced. Antioxidants (Trolox, Probucol) reduced the cytotoxic effect of alcohol and VLDL. Supernatants of alcohol/VLDL-treated PAC stimulated stellate cell proliferation and extracellular matrix synthesis. We concluded that, in the presence of lipoproteins, alcohol induces acinar cell injury. Our results provide a biochemical pathway for the clinical observation that a fat-enriched meal combined with excess alcohol consumption can induce acinar cell injury (acute pancreatitis) followed by repair mechanisms (proliferation and increased matrix synthesis in PSC).ethanol; free radicals; pancreas THE MECHANISM OF ALCOHOLIC PANCREATITIS is incompletely understood. Despite the fact that about 40% of acute pancreatitis and 70% of chronic pancreatitis in humans are induced by alcohol, most alcoholics will never be affected by any of these diseases. As calculated by Ammann et al. (1), only 5% of all alcohol abusers will develop alcoholic pancreatitis. Interestingly enough, this can also be observed in setups with animals where acute pancreatitis cannot be induced by alcohol itself (8,15,25). Therefore, additional factors accompanying alcohol intake must be coresponsible for the induction of the disease. Some of these cofactors such as stimulation of pancreatic secretion and/or obstruction of pancreatic outflow have been experimentally observed by us and others (8,12,25,26).Clinical experience has taught us that a large number of patients presenting an acute event of alcoholic pancreatitis have drunk lots of alcohol together with an opulent (fat enriched) meal the day before onset of the disease. In the present ...

Pancreatic Fat Accumulation, Fibrosis, and Acinar Cell Injury in the Zucker Diabetic Fatty Rat Fed a Chronic High-Fat Diet

“…It is known that pancreatic stellate cells (PSCs) are activated by ethanol and its metabolites, and also by cytokines and oxidant stress, in the process of pancreatic fibrosis 45. Only a few detailed studies of pancreatic fibrosis using obesity models or high-fat–fed animals have been reported 46,47.…”

“…However, no previous study of either animal models or human patients has evaluated the histological changes that occur during the transition from pancreatic fat accumulation to fibrosis. In the only study to have used acinar cells isolated from Wistar rats, very low-density lipoprotein was shown to induce acinar cell injury in the absence of alcohol, with subsequent PSC proliferation and synthesis of extracellular matrix 45. In the present study, temporal histological changes in the pancreatic tissue of ZDF rats were evaluated for the first time, and it was found that fat accumulation in acinar cells and subsequent pancreatic fibrosis appeared to increase upon chronic exposure to a high-fat diet.…”

Isolation and characterization of islet stellate cells in rat

“…5 Since the first identification of PSCs, numerous in vivo and in vitro studies have provided strong evidence of a central role of PSCs in pancreatic fibrogenesis associated with chronic pancreatitis and pancreatic cancer. [5][6][7][8][9][10][11][12] Fibrotic responses to inflammatory insults may also be important in pathological responses in the endocrine portion of the pancreas, the islets of Langerhans. Islet fibrosis has been demonstrated in the pancreas of humans with T2DM, and in a number of animal models of diabetes, [13][14][15][16][17][18] where it is associated with the late stage of β cell failure during the progression to T2DM.…”

Role of pancreatic fat in the outcomes of pancreatitis

“…Apart from alcohol, animal models have shown that chronic high fat diets in rats induce fibrogenesis too [76, 77]. In vitro studies [78], rodent models using high fat diets [76, 79] and studies on tissue from patients with chronic pancreatitis support lipid peroxidation products to play a role in stellate cell activation and fibrogenesis. The predominant collagen present in fibrous tissue, produced by the PSC is type I collagen [80–82], with other components of the ECM being mainly proteoglycans.…”