Theories, mechanisms, and models of alcoholic chronic pancreatitis

Urolithin A attenuates severity of chronic pancreatitis associated with continued alcohol intake by inhibiting PI3K/AKT/mTOR signaling

Heavy alcohol consumption is the dominant risk factor for chronic pancreatitis (CP); however, treatment and prevention strategies for alcoholic chronic pancreatitis (ACP) remains limited. The present study demonstrates that ACP induction in C57BL/6 mice causes significant acinar cell injury, pancreatic stellate cell (PSC) activation, exocrine function insufficiency, and an increased fibroinflammatory response when compared with alcohol or CP alone. Although the withdrawal of alcohol during ACP recovery led to reversion of pancreatic damage, continued alcohol consumption with established ACP perpetuated pancreatic injury. In addition, phosphokinase array and Western blot analysis of ACP-induced mice pancreata revealed activation of the phosphatidylinositol 3 kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and cyclic AMP response element binding protein (CREB) signaling pathways possibly orchestrating the fibroinflammatory program of ACP pathogenesis. Mice treated with urolithin A (Uro A, a gut-derived microbial metabolite) in the setting of ACP with continued alcohol intake (during the recovery period) showed suppression of AKT and P70S6K activation, and acinar damage was significantly reduced with a parallel reduction in pancreas-infiltrating macrophages and proinflammatory cytokine accumulation. These results collectively provide mechanistic insight into the impact of Uro A on attenuation of ACP severity through suppression of PI3K/AKT/mTOR signaling pathways and can be a useful therapeutic approach in patients with ACP with continuous alcohol intake.NEW & NOTEWORTHY Our novel findings presented here demonstrate the utility of Uro A as an effective therapeutic agent in attenuating alcoholic chronic pancreatitis (ACP) severity with alcohol continuation after established disease, through suppression of the PI3K/AKT/mTOR signaling pathway.

Repeated Stimulation of Toll-Like Receptor 2 and Dectin-1 Induces Chronic Pancreatitis in Mice Through the Participation of Acquired Immunity

BACKGROUND

Stimulation of Toll-like receptor 3 (TLR3) induces autoimmune-mediated pancreatitis in susceptible mice, whereas stimulation of TLR4 causes nonautoimmune-mediated pancreatitis. However, the effects of TLR2 stimulation on the pancreas are unknown.

AIMS

We investigated the role of TLR2 stimulation on pancreatic damage by repeatedly stimulating mice with TLR2 ligands.

METHODS

Wild-type (WT) and interleukin 10-deficient (IL-10-knockout (KO)) mice were administered zymosan and lipoteichoic acid (LTA) intraperitoneally at various doses twice weekly for 4 weeks. Syngeneic T-cell-deficient mice, B-cell-deficient mice, recombination activating gene 2-deficient (RAG2-KO) mice and RAG2-KO mice that had been reconstituted with CD4⁺ or CD8⁺ T cells isolated from WT mice were treated with zymosan similarly. Mice were killed, the severity of pancreatitis was graded histologically, and serum cytokine levels were measured.

RESULTS

Repeated administration of zymosan induced pancreatitis dose dependently in both WT and IL-10-KO mice. Administration of LTA induced pancreatitis only in IL-10-KO mice. Adoptive transfer of splenocytes obtained from IL-10-KO mice with pancreatitis did not cause pancreatitis in recipient RAG2-KO mice. Pancreatitis was scarcely observed in RAG2-KO mice and was attenuated in T-cell-deficient and B-cell-deficient mice compared with WT mice. A single administration of zymosan significantly increased the serum level of monocyte chemoattractant protein 1 (MCP-1) in WT mice.

CONCLUSIONS

Repeated stimulation of TLR2 and dectin-1 induced nonautoimmune-mediated pancreatitis in mice. Participation of acquired immunity seems to play an important role in the pathogenesis of pancreatitis in association with the increase in serum MCP-1 level.

Adamts1 mediates ethanol-induced alterations in collagen and elastin via a FoxO1-sestrin3-AMPK signaling cascade in myocytes

A variety of stressors including alcohol (EtOH) are known to induce collagen production and fibrotic diseases. Matrix metalloproteinases (MMP) play an important role in regulating fibrosis, but little is known regarding the relationship between EtOH and MMPs. In addition, the signaling cascades involved in this process have not been elucidated. We have identified the MMP Adamts1 as a target of EtOH regulation. To characterize the function of Adamts1, we examined EtOH-induced alterations in collagen I and elastin protein levels in C2C12 myocytes. Incubation of myocytes with 100 mM EtOH decreased elastin and increased collagen content, respectively, and these changes were associated with increased O-GLcNAc modification of Adamts1. Conversely, silencing of Adamts1 by siRNA blocked the adverse effects of EtOH on collagen and elastin levels. Similar results were obtained after treatment with a pharmacological inhibitor of MMP. Changes in collagen were due, at least in part, to a decreased interaction of Adamts1 with its endogenous inhibitor TIMP3. The AMPK inhibitor compound C blocked the EtOH-induced stimulation of collagen and O-GLcNAc Adamts1 protein. Changes in AMPK appear linked to FoxO1, since inhibition of FoxO1 blocked the effects of EtOH on AMPK phosphorylation and O-GLcNAc levels. These FoxO-dependent modifications were associated with an upregulation of the FoxO1 transcription target sestrin 3, as well as increased binding of sestrin 3 with AMPK. Collectively, these data indicate that EtOH regulates the collagen I and elastin content in an Adamts1-dependent manner in myocytes. Furthermore, Adamts1 appears to be controlled by the FoxO1-sestrin 3-AMPK signaling cascade.

Acquired immunity plays an important role in the development of murine experimental pancreatitis induced by alcohol and lipopolysaccharide

OBJECTIVE

Although chronic alcohol ingestion is the major cause of chronic pancreatitis, less than 10% of alcohol abusers develop this disease. To address this issue, we created a murine model of pancreatitis induced by alcohol and lipopolysaccharide (LPS) and analyzed its immune responses.

METHODS

C57BL/6 mice were administered 20% ethanol (AL) in their drinking water and then injected intraperitoneally with LPS twice weekly for 4 weeks. Severe combined immunodeficient mice were reconstituted with splenocytes, CD4 cells, or CD8 T cells isolated from wild-type mice and then treated similarly. The severity of pancreatitis was graded histologically, and serum cytokine levels were measured.

RESULTS

Ethanol alone did not cause pancreatitis. However, the administration of AL+LPS or LPS alone induced pancreatitis. The histological scores were higher in the mice treated with AL+LPS than in those treated with LPS. Serum levels of interleukin 1β, interferon-γ, and tumor necrosis factor α were elevated in the AL+LPS-treated mice. The severe combined immunodeficient mice developed pancreatitis only after their reconstitution with splenocytes, CD4 cells, or CD8 T cells.

CONCLUSIONS

Repeated stimulation of the innate immune system is necessary, but not sufficient, to cause pancreatitis. The participation of the acquired immune response is essential for the development of the disease.

Alcohol consumption on pancreatic diseases

Although the association between alcohol and pancreatic diseases has been recognized for a long time, the impact of alcohol consumption on pancreatitis and pancreatic cancer (PC) remains poorly defined. Nowadays there is not consensus about the epidemiology and the beverage type, dose and duration of alcohol consumption causing these diseases. The objective of this study was to review the epidemiology described in the literature for pancreatic diseases as a consequence of alcoholic behavior trying to understand the association between dose, type and frequency of alcohol consumption and risk of pancreatitis and PC. The majority of the studies conclude that high alcohol intake was associated with a higher risk of pancreatitis (around 2.5%-3% between heavy drinkers and 1.3% between non drinkers). About 70% of pancreatitis are due to chronic heavy alcohol consumption. Although this incidence rate differs between countries, it is clear that the risk of developing pancreatitis increases with increasing doses of alcohol and the average of alcohol consumption vary since 80 to 150 g/d for 10-15 years. With regard to PC, the role of alcohol consumption remains less clear, and low to moderate alcohol consumption do not appear to be associated with PC risk, and only chronic heavy drinking increase the risk compared with lightly drinkers. In a population of 10%-15% of heavy drinkers, 2%-5% of all PC cases could be attributed to alcohol consumption. However, as only a minority (less than 10% for pancreatitis and 5% for PC) of heavily drinkers develops these pancreatic diseases, there are other predisposing factors besides alcohol involved. Genetic variability and environmental exposures such as smoking and diet modify the risk and should be considered for further investigations.

Ethanol administration impairs pancreatic repair after injury

OBJECTIVES

Alcohol abuse is one of the most common factors associated with acute and chronic pancreatitis. Although it is evident that alcohol abuse can have an important role in the development of pancreatitis, it does not seem that alcohol abuse alone is responsible for this disease. We investigated the involvement of ethanol in the impairment of pancreatic repair after induction of pancreatitis.

METHODS

A biologically relevant mouse model of alcoholic pancreatitis, combining long-term ethanol consumption and coxsackievirus infection, was used to investigate the effects of ethanol on pancreatic regeneration. Tissues were harvested and analyzed by reverse transcription-polymerase chain reaction and immunoblot.

RESULTS

These studies demonstrate that long-term ethanol consumption impairs the structural repair of the exocrine pancreas. This is accompanied by a delay in the restitution of lipase expression. In addition, impaired expression of the critical pancreatic transcription factors, PDX1 and PTF1, and the mediator of Notch signaling, HES1, was observed.

CONCLUSIONS

Long-term ethanol consumption impairs the structural repair and functional restitution of the pancreas after severe injury. These impairments may, in part, be explained by the impaired expression of factors important in the development and maintenance of the exocrine pancreas. Impaired pancreatic regeneration may have a role in the pathogenesis of alcoholic pancreatitis.

Investigating the pathobiology of alcoholic pancreatitis

Alcohol abuse is one of the most common causes of pancreatitis. The risk of developing alcohol-induced pancreatitis is related to the amount and duration of drinking. However, only a small portion of heavy drinkers develop disease, indicating that other factors (genetic, environmental, or dietary) contribute to disease initiation. Epidemiologic studies suggest roles for cigarette smoking and dietary factors in the development of alcoholic pancreatitis. The mechanisms underlying alcoholic pancreatitis are starting to be understood. Studies from animal models reveal that alcohol sensitizes the pancreas to key pathobiologic processes that are involved in pancreatitis. Current studies are focussed on the mechanisms responsible for the sensitizing effect of alcohol; recent findings reveal disordering of key cellular organelles including endoplasmic reticulum, mitochondria, and lysosomes. As our understanding of alcohol's effects continue to advance to the level of molecular mechanisms, insights into potential therapeutic strategies will emerge providing opportunities for clinical benefit.

Connective tissue growth factor production by activated pancreatic stellate cells in mouse alcoholic chronic pancreatitis

Alcoholic chronic pancreatitis (ACP) is characterized by pancreatic necrosis, inflammation, and scarring, the latter of which is due to excessive collagen deposition by activated pancreatic stellate cells (PSC). The aim of this study was to establish a model of ACP in mice, a species that is usually resistant to the toxic effects of alcohol, and to identify the cell type(s) responsible for production of connective tissue growth factor (CTGF), a pro-fibrotic molecule. C57Bl/6 male mice received intraperitoneal ethanol injections for 3 weeks against a background of cerulein-induced acute pancreatitis. Peak blood alcohol levels remained consistently high in ethanol-treated mice as compared with control mice. In mice receiving ethanol plus cerulein, there was increased collagen deposition as compared with other treatment groups as well as increased frequency of alpha-smooth muscle actin and desmin-positive PSC, which also showed significantly enhanced CTGF protein production. Expression of mRNA for collagen alpha1(I), alpha-smooth muscle actin or CTGF were all increased and co-localized exclusively to activated PSC in ACP. Pancreatic expression of mRNA for key profibrotic markers were all increased in ACP. In conclusion, a mouse model of ACP has been developed that mimics key pathophysiological features of the disease in humans and which shows that activated PSC are the principal producers of collagen and CTGF. PSC-derived CTGF is thus a candidate therapeutic target in anti-fibrotic strategies for ACP.

Alcoholic pancreatitis: pathogenesis, incidence and treatment with special reference to the associated pain

Alcoholic pancreatitis continues to stir up controversy. One of the most debated points is whether from onset it is a chronic disease or whether it progresses to a chronic form after repeated episodes of acute pancreatitis. Histological studies on patients with alcoholic pancreatitis have shown that the disease is chronic from onset and that alcoholic acute pancreatitis occurs in a pancreas already damaged by chronic lesions. Genetic factors may also play a role in the pathogenesis of alcoholic disease. The incidence of chronic alcoholic pancreatitis seems to have decreased in the last twenty years. Finally, recent therapeutic studies which have shown medical or surgical approaches capable of reducing the pain episodes in chronic pancreatitis patients will be described.

Alcohol use and risk of pancreatic cancer: the NIH-AARP Diet and Health Study

The epidemiologic evidence for the role of alcohol use in pancreatic cancer development is equivocal. The authors prospectively examined the relation between alcohol use and risk of pancreatic cancer among 470,681 participants who were aged 50-71 years in 1995-1996 in the US National Institutes of Health-AARP Diet and Health Study. The authors identified 1,149 eligible exocrine pancreatic cancer cases through December 2003. Multivariate Cox proportional hazards regression models were used to calculate relative risks and 95% confidence intervals with the referent group being light drinkers (<1 drink/day). The relative risks of developing pancreatic cancer were 1.45 (95% confidence interval (CI): 1.17, 1.80; P(trend) = 0.002) for heavy total alcohol use (>or=3 drinks/day, approximately 40 g of alcohol/day) and 1.62 (95% CI: 1.24, 2.10; P(trend) = 0.001) for heavy liquor use, compared with the respective referent group. The increased risk with heavy total alcohol use was seen in never smokers (relative risk = 1.35, 95% CI: 0.79, 2.30) and participants who quit smoking 10 or more years ago before baseline (relative risk = 1.41, 95% CI: 1.01, 2.00). These findings suggest a moderately increased pancreatic cancer risk with heavy alcohol use, particularly liquor; however, residual confounding by cigarette smoking cannot be completely excluded.

Relationship between hs-CRP and cardiac efficiency in chronic alcoholics

High sensitive C-reactive protein (hs-CRP), a non-specific marker of inflammatory status has considerable interest focused due to its ability to predict myocardial infarction, stroke, peripheral arterial disease and sudden cardiac death. Alcoholics are known to be associated with inflammation of heart. This study was taken up to look for an association between consumption of alcoholic beverages over 10 years and serum concentration of hs-CRP. 3 groups were studied, 30 age matched control, 30 non-drinkers with cardio vascular complications and 30 alcoholics with history of cardio-vascular disease. Blood was analyzed for hs-CRP. Results indicated that the level of hs-CRP was 0.17 ± 0.16 mg/lit in group 1; 0.79 ± 0.41 mg/lit in group 2 and 1.67 ± 0.16 mg/lit in group 3. A correlation was also obtained between the hs-CRP levels and cardiac efficiency in chronic alcoholics. The elevated hs-CRP levels in chronic alcoholic with heart disease could probably be due to enhanced damaging effect of alcohol on the heart and other organs.

A rat model reproducing key pathological responses of alcoholic chronic pancreatitis

Although alcohol abuse is the major cause of chronic pancreatitis, the pathogenesis of alcoholic chronic pancreatitis (ACP) remains obscure. A critical obstacle to understanding the mechanism of ACP is lack of animal models. Our objective was to develop one such model. Rats were pair-fed for 8 wk ethanol or control Lieber-DeCarli liquid diet. For the last 2 wk, they received cyclosporin A (CsA; 20 mg/kg once daily) or vehicle. After 1 wk on CsA, one episode of acute pancreatitis was induced by four 20 microg/kg injections of cerulein (Cer); controls received saline. Pancreas was analyzed 1 wk after the acute pancreatitis. CsA or Cer treatments alone did not result in pancreatic injury in either control (C)- or ethanol (E)-fed rats. We found, however, that alcohol dramatically aggravated pathological effect of the combined CsA+Cer treatment on pancreas, resulting in massive loss of acinar cells, persistent inflammatory infiltration, and fibrosis. Macrophages were prominent in the inflammatory infiltrate. Compared with control-fed C+CsA+Cer rats, their ethanol-fed E+CsA+Cer counterparts showed marked increases in pancreatic NF-kappaB activation and cytokine/chemokine mRNA expression, collagen and fibronectin, the expression and activities of matrix metalloproteinase-2 and -9, and activation of pancreatic stellate cells. Thus we have developed a model of alcohol-mediated postacute pancreatitis that reproduces three key responses of human ACP: loss of parenchyma, sustained inflammation, and fibrosis. The results indicate that alcohol impairs recovery from acute pancreatitis, suggesting a mechanism by which alcohol sensitizes pancreas to chronic injury.

[Inflammatory pancreatic disease due to enzyme autodigestion: an exceptional model of glandular crinophagy]

The exocrine pancreas is a functionally dangerous structure since it is exposed to digestion by its most aggressive enzymes (proteases, etc) despite self-protective measures such as the synthesis of some of these enzymes in the form of inactive zymogens (trypsinogen, etc.). We review inflammatory pancreatic disease by separately analyzing its classical forms of onset: acute and chronic pancreatitis (AP and CP). There is general consensus that the initial pathogenic event in AP is intraacinar activation of trypsinogen into trypsin, followed by that of the remaining proenzymes, giving rise to an unusual model of autophagic inflammation. In contrast, consensus is lacking on the initial pathogenic event in CP (toxic-metabolic lesion, oxidative stress, ductal hypertension, etc.?), although in some cases a <<necrosis-fibrosis>> sequence due to recurrent episodes of AP seems evident. The pathogenic features shared by both forms of the disease and which justify some recent attempts to formulate an overall explanation of the pathogenesis of pancreatitis are discussed. Such an explanation would place both forms of pancreatitis within the conceptual framework of an <<inflammatory pancreatic disease due to enzyme autodigestion>>.

Pathobiology of alcoholic pancreatitis

This paper provides a summary of the effects of alcohol abuse on the pathobiologic responses that occur during acute and chronic pancreatitis considering both the human disease and animal/tissue models. The effects are multiple and include ones on cell death leading to necrosis; on inflammation resulting in a sensitized response to pancreatic stress; and fibrosis through effects of ethanol on pancreatic stellate cells and the plasminogen system. Although the effects of alcohol are multiple and complex, it is likely that a combination of a few key effects on these pathobiologic responses drive the increased sensitivity of the pancreas to acute pancreatitis with pancreatic stress and the promotion of chronic pancreatitis with pancreatic injury occurring during acute pancreatitis.

A search for acute necrotic pancreatitis in early stages of alcoholic chronic pancreatitis

OBJECTIVES

Various investigators believe that alcoholic chronic pancreatitis is the result of recurrent episodes of acute necrotic pancreatitis. The aim of this work is to study pancreatic histology in early stages of the disease to search for evidence of these acute episodes.

STUDY

Of about 650 patients with alcoholic pancreatitis seen during the 30-year period from 1972 to 2002, 45 underwent surgery for this disease, all within 2 years of clinical onset. Of these 45, tissue samples adequate for study were obtained from 42, and this was the study material. Tissue samples were prepared for histologic examination by standard procedures.

RESULTS

Areas of pancreatic necrosis were seen in tissue samples of only three (7%) of the 42 patients, and in all three cases chronic lesions were also present. No evidence of localized scarring that could be attributed to prior episodes of focal necrotic pancreatitis was found. A typical feature was the patchy distribution of the lesions in largely normal pancreatic tissue. The main lesions observed were perilobular and intralobular fibrosis, dilation of acini and ducts, and protein plugs in dilated ducts surrounded by periductal fibrosis.

CONCLUSIONS

This study shows that, in the early stages of alcoholic chronic pancreatitis, signs of acute necrotic pancreatitis are very infrequent and, when present, they are associated with chronic lesions. These findings suggest that alcoholic pancreatitis begins as a chronic disease.