Role of Bile Acids and Bile Salts in Acute Pancreatitis: From the Experimental to Clinical Studies

Longitudinal Pancreatojejunostomy for Pancreaticodigestive Reconstruction in the Resection of Pancreatic Head Malignancy with Chronic Pancreatitis: A Case Report

INTRODUCTION

With progress in pancreatic surgery, a preservation of residual organ function has become more important. Pancreatic malignancies are occasionally accompanied by chronic pancreatitis (CP) and pancreatolithiasis (PL). Longitudinal pancreatojejunostomy (LPJ) is reportedly a useful method of surgical management in cases of CP with PL. We describe a patient with pancreatic head intraductal papillary mucinous carcinoma (IPMC) concomitant with PL, who underwent subtotal stomach-preserving pancreaticoduodenectomy (SSPPD) and LPJ for reconstruction.

CASE PRESENTATION

A man in his 70s was referred to our hospital with a pancreatic head tumor. He had been treated for CP, diabetes mellitus, and chronic kidney disease. Imaging revealed a cystic pancreatic head tumor with a solid component that was histologically confirmed as IPMC. In addition, multiple calcifications suggestive of PL were observed in the pancreatic body and tail. SSPPD and LPJ were performed to excise the PL as much as possible and preserve the residual pancreatic function. The postoperative course was uneventful, and no abdominal symptoms or tumor recurrences were observed for approximately 8 months after surgery.

CONCLUSION

This patient with IPMC with residual pancreatic PL was treated with SSPPD and LPJ to maximize the residual pancreatic function and reduce the occurrence of postoperative pancreatitis.

Broccoli (Brassica oleracea L. var. italica Planch) alleviates metabolic-associated fatty liver disease through regulating gut flora and lipid metabolism via the FXR/LXR signaling pathway

The increased consumption of dietary fats contributes to the development of MAFLD (metabolic fatty liver disease). The ability of broccoli to enhance lipid metabolism has attracted researchers' attention. Researchers fed C57BL/6 mice a 12-week HFD to ensure the induction of MAFLD. The findings indicated that broccoli floret juice could effectively relieve MAFLD. Broccoli is helpful for reducing weight, blood glucose levels, fat accumulation, and insulin resistance associated with MAFLD and reduces the concentrations of TC, TG, LDL-C, GOT, GPT, IL-1β, IL-6, CCL4, and MCP1. Broccoli can increase the concentration of HDL-C, CAT, GSH-Px, SOD, and T-AOC, relieve inflammation and hepatic and ileum damage, and improve the antioxidant capacity of the body. Also, broccoli can optimize the structure of intestinal flora, promote the growth of Allobaculum, Muribaculaceae, Akkermansia, Eubacterium, and Bacteroides, and reduce bile acid deposition. In addition, the FXR/LXRα signaling system is impacted by broccoli, which is capable of raising the average levels of expression of the Fxr, SHP, and Cyp7a1 genes and proteins and reducing those of the genes for Fasn, Lpin 1, Dgat 2, Scd1, LXRα, and SREBP-1c.

Mitochondrial dysfunction in the pathogenesis of acute pancreatitis

The mechanism of cell damage during acute pancreatitis (AP) has not been fully elucidated, and there is still a lack of specific or effective treatments. Increasing evidence has implicated mitochondrial dysfunction as a key event in the pathophysiology of AP. Mitochondrial dysfunction is closely related to calcium (Ca2+) overload, intracellular adenosine triphosphate depletion, mitochondrial permeability transition pore openings, loss of mitochondrial membrane potential, mitophagy damage and inflammatory responses. Mitochondrial dysfunction is an early triggering event in the initiation and development of AP, and this organelle damage may precede the release of inflammatory cytokines, intracellular trypsin activation and vacuole formation of pancreatic acinar cells. This review provides further insight into the role of mitochondria in both physiological and pathophysiological aspects of AP, aiming to improve our understanding of the underlying mechanism which may lead to the development of therapeutic and preventive strategies for AP.

Cholic acid activation of GPBAR1 does not induce or exacerbate acute pancreatitis but promotes exocrine pancreatic secretion

Obstruction of bile ducts due to gallstones can lead to biliary acute pancreatitis (BAP). According to Perides et al., G protein-coupled bile acid receptor-1 (GPBAR1) mediates BAP. However, Zi's findings suggest that GPR39, rather than GPBAR1, mediates TLCAS-induced increases in cytosolic calcium and acinar cell necrosis, casting doubt on the role of GPBAR1 in BAP. Numerous G protein-coupled receptors on pancreatic acinar cells utilize Ca2+ and cyclic adenosine monophosphate (cAMP) as second messengers to manage pancreatic exocrine secretion, with significant cross-talk between these signals. The primary bile acid cholic acid (CA) and its conjugated forms are predominant in the human gallbladder. This study aimed to clarify the role and physiological significance of GPBAR1 by investigating the physiological and pathological effects of CA activation on GPBAR1 in pancreatic acinar cells. Isolated rat pancreatic acinar cells were treated with CA and CCK in vitro to observe the effect of CA-induced cAMP signaling on CCK-induced physiological and pathological calcium signaling. In vivo evaluations involved reverse biliopancreatic duct injections of 5 % sodium taurocholate (STC) or 5 % CA in rats. CA induced intracellular cAMP signaling in a concentration-dependent manner without increasing the intracellular Ca2+ concentration. CA did not independently cause calcium overload or enzyme activation, nor did it exacerbate calcium overload or enzyme activation from high-dose CCK. Reverse biliopancreatic duct injections of 5 % CA did not cause acute pancreatitis in the rats. Transcriptomic analysis revealed that 50 μM CA induced changes in gene expression related to protein synthesis in the endoplasmic reticulum and ribosomes. Furthermore, 50 μM CA accelerated the calcium waves and increased the enzyme secretion induced by CCK. GPBAR1 was found on the basolateral membrane in rat pancreatic tissue rather than near the apical region of acinar cells. GPBAR1 activation is not crucial for BAP activity but may play a role in bile acid regulation of pancreatic exocrine secretion, suggesting that GPBAR1 is a potential therapeutic target for pancreatic exocrine insufficiency.

Integrated global and unique metabolic characteristics to reveal the intervention effect of Yiyi decoction on acute pancreatitis

Yiyi decoction is a Chinese herbal formula for the treatment of acute pancreatitis that has been used in clinical practice for decades. A previous study has suggested that resveratrol, emodin, rhein and their derivatives might be the potential pharmacodynamic components in Yiyi decoction, and researchers have proposed that resveratrol, emodin and rhein are candidate markers for quality control. The present study investigated the intervention effect of Yiyi decoction and its effective components on murine acute pancreatitis using metabolomic approach that integrated global and unique metabolic characteristics. First, serum metabolomics based on the platform of ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was performed to assess metabolic changes in experimental acute pancreatitis. Second, an in-depth analysis of bile acid metabolism was performed based on an in-house database. Finally, an integrated analysis of the intervention effect of Yiyi decoction and its effective components in response to these metabolic perturbations was performed. As a result, 39 potential biomarkers for the pathogenesis of acute pancreatitis, mainly phospholipids, fatty acids, bile acids and lipoylcarnitines, were screened and annotated. Integrated analysis revealed that the metabolic disorders in acute pancreatitis mice were reversed by Yiyi decoction primarily via regulating glycerophospholipid metabolism, bile acid biosynthesis, carnitine synthesis and fatty acid metabolism. Yiyi decoction components may effectively target the migratory metabolome. Histopathological and biochemical analyses suggested that Yiyi decoction maintained the gut barrier function and inhibited inflammatory cytokines, thus exert anti-acute pancreatitis effects. The present study utilized an approach that integrated global and unique metabolic characteristics to elucidate the underlying mechanisms of Chinese herbal formulas from a metabolomics perspective.

Intestinal microflora and metabolites affect the progression of acute pancreatitis (AP)

Specific intestinal metabolites are closely associated with the classification, severity, and necrosis of acute pancreatitis (AP) and provide novel insights for in-depth clinical investigations. In this study, the gut microbiota and metabolites of 49 AP patients at different treatment stages and severities were analysed via 16S rDNA sequencing and untargeted metabolomics to investigate the trends in gut microbiota composition and metabolome profiles observed in patients with severe AP. These findings revealed an imbalance in intestinal flora homeostasis among AP patients characterized by a decrease in probiotics and an increase in opportunistic pathogens, which leads to damage to the intestinal mucosal barrier through reduced short-chain fatty acid (SCFA) secretion and disruption of the intestinal epithelium. This dysbiosis influences energy metabolism, anti-inflammatory responses, and immune regulation, and these results highlight significant differences in energy metabolism pathways. These findings suggest that the differential composition of intestinal flora, along with alterations in intestinal metabolites and metabolic pathways, contribute to the compromised integrity of the intestinal mucosal barrier and disturbances in energy metabolism in patients with severe AP.

The role of gut microbiome and its metabolites in pancreatitis

Gut microbiome plays a vital role in the intestinal ecosystem and has close association with metabolites. Due to the development of metabolomics and microbiomics, recent studies have observed that alteration of either the gut microbiome or metabolites may have effects on the progression of pancreatitis. Several new treatments based on the gut microbiome or metabolites have been studied extensively in recent years. Gut microbes, such as Bifidobacterium, Akkermansia, and Lactobacillus, and metabolites, such as short-chain fatty acids, bile acids, vitamin, hydrogen sulfide, and alcohol, have different effects on pancreatitis. Some preliminary studies about new intervention measures were based on the gut microbiome and metabolites such as diet, prebiotic, herbal medicine, and fecal microbiota transplantation. This review aims to summarize the recent advances about the gut microbiome, metabolites, and pancreatitis in order to determine the potential beneficial role of the gut microbiome and metabolites in pancreatitis.

Integrative metagenomic and metabolomic analyses reveal the potential of gut microbiota to exacerbate acute pancreatitis

Early dysbiosis in the gut microbiota may contribute to the severity of acute pancreatitis (AP), however, a comprehensive understanding of the gut microbiome, potential pathobionts, and host metabolome in individuals with AP remains elusive. Hence, we employed fecal whole-metagenome shotgun sequencing in 82 AP patients and 115 matched healthy controls, complemented by untargeted serum metabolome and lipidome profiling in a subset of participants. Analyses of the gut microbiome in AP patients revealed reduced diversity, disrupted microbial functions, and altered abundance of 77 species, influenced by both etiology and severity. AP-enriched species, mostly potential pathobionts, correlated positively with host liver function and serum lipid indicators. Conversely, many AP-depleted species were short-chain fatty acid producers. Gut microflora changes were accompanied by shifts in the serum metabolome and lipidome. Specifically, certain gut species, like enriched Bilophila wadsworthia and depleted Bifidobacterium spp., appeared to contribute to elevated triglyceride levels in biliary or hyperlipidemic AP patients. Through culturing and whole-genome sequencing of bacterial isolates, we identified virulence factors and clinically relevant antibiotic resistance in patient-derived strains, suggesting a predisposition to opportunistic infections. Finally, our study demonstrated that gavage of specific pathobionts could exacerbate pancreatitis in a caerulein-treated mouse model. In conclusion, our comprehensive analysis sheds light on the gut microbiome and serum metabolome in AP, elucidating the role of pathobionts in disease progression. These insights offer valuable perspectives for etiologic diagnosis, prevention, and intervention in AP and related conditions.

Discoveries of GPR39 as an evolutionarily conserved receptor for bile acids and of its involvement in biliary acute pancreatitis

Acute pancreatitis (AP) is one of the most common gastrointestinal diseases. Bile acids (BAs) were proposed to be a cause of AP nearly 170 years ago, though the underlying mechanisms remain unclear. Here, we report that two G protein-coupled receptors, GPR39 and GHSR, mediated cellular responses to BAs. Our results revealed GPR39 as an evolutionarily conserved receptor for BAs, particularly 3-O-sulfated lithocholic acids. In cultured cell lines, GPR39 is sufficient for BA-induced Ca2+ elevation. In pancreatic acinar cells, GPR39 mediated BA-induced Ca2+ elevation and necrosis. Furthermore, AP induced by BAs was significantly reduced in GPR39 knockout mice. Our findings provide in vitro and in vivo evidence demonstrating that GPR39 is necessary and sufficient to mediate BA signaling, highlighting its involvement in biliary AP pathogenesis, and suggesting it as a promising therapeutic target for biliary AP.

The Role of Bile Acids in Pancreatic Cancer

Bile acids are well known to promote the digestion and absorption of fat, and at the same time, they play an important role in lipid and glucose metabolism. More studies have found that bile acids such as ursodeoxycholic acid also have anti-inflammatory and immune-regulating effects. Bile acids have been extensively studied in biliary and intestinal tumors but less in pancreatic cancer. Patients with pancreatic cancer, especially pancreatic head cancer, are often accompanied by biliary obstruction and elevated bile acids caused by tumors. Elevated total bile acid levels in pancreatic cancer patients usually have a poor prognosis. There has been controversy over whether elevated bile acids are harmful or beneficial to pancreatic cancer. Still, there is no doubt that bile acids are important for the occurrence and development of pancreatic cancer. This article summarizes the research on bile acid as a biomarker and regulation of the occurrence, development and chemoresistance of pancreatic cancer, hoping to provide some inspiration for future research.

Targeting Farnesoid X Receptor in Tumor and the Tumor Microenvironment: Implication for Therapy

The farnesoid-X receptor (FXR), a member of the nuclear hormone receptor superfamily, can be activated by bile acids (BAs). BAs binding to FXR activates BA signaling which is important for maintaining BA homeostasis. FXR is differentially expressed in human organs and exists in immune cells. The dysregulation of FXR is associated with a wide range of diseases including metabolic disorders, inflammatory diseases, immune disorders, and malignant neoplasm. Recent studies have demonstrated that FXR influences tumor cell progression and development through regulating oncogenic and tumor-suppressive pathways, and, moreover, it affects the tumor microenvironment (TME) by modulating TME components. These characteristics provide a new perspective on the FXR-targeted therapeutic strategy in cancer. In this review, we have summarized the recent research data on the functions of FXR in solid tumors and its influence on the TME, and discussed the mechanisms underlying the distinct function of FXR in various types of tumors. Additionally, the impacts on the TME by other BA receptors such as takeda G protein-coupled receptor 5 (TGR5), sphingosine-1-phosphate receptor 2 (S1PR2), and muscarinic receptors (CHRM2 and CHRM3), have been depicted. Finally, the effects of FXR agonists/antagonists in a combination therapy with PD1/PD-L1 immune checkpoint inhibitors and other anti-cancer drugs have been addressed.

Farnesoid X receptor activation inhibits pancreatic carcinogenesis

Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily that controls bile acid (BA) homeostasis, has also been proposed as a tumor suppressor for breast and liver cancer. However, its role in pancreatic ductal adenocarcinoma (PDAC) tumorigenesis remains controversial. We recently found that FXR attenuates acinar cell autophagy in chronic pancreatitis resulting in reduced autophagy and promotion of pancreatic carcinogenesis. Feeding Kras-p48-Cre (KC) mice with the BA chenodeoxycholic acid (CDCA), an FXR agonist, attenuated pancreatic intraepithelial neoplasia (PanIN) progression, reduced cell proliferation, neoplastic cells and autophagic activity, and increased acinar cells, elevated pro-inflammatory cytokines and chemokines, with a compensatory increase in the anti-inflammatory response. Surprisingly, FXR-deficient KC mice did not show any response to CDCA, suggesting that CDCA attenuates PanIN progression and decelerate tumorigenesis in KC mice through activating pancreatic FXR. FXR is activated in pancreatic cancer cell lines in response to CDCA in vitro. FXR levels were highly increased in adjuvant and neoadjuvant PDAC tissue compared to healthy pancreatic tissue, indicating that FXR is expressed and potentially activated in human PDAC. These results suggest that BA exposure activates inflammation and suppresses autophagy in KC mice, resulting in reduced PanIN lesion progression. These data suggest that activation of pancreatic FXR has a protective role by reducing the growth of pre-cancerous PDAC lesions in response to CDCA and possibly other FXR agonists.

How do different bile acid derivatives affect rat macrophage function - Friends or foes?

Due to an increased need for new immunomodulatory agents, many previously known molecules have been structurally modified in order to obtain new drugs, preserving at the same time some of the benevolent characteristics of the parent molecule. This study aimed to evaluate the immunomodulatory potential of a selected library of bile acid derivatives (BAD) using a broad spectrum of assays, evaluating rat peritoneal macrophages viability, cell membrane damage, lysosomal and adhesion function, and nitric oxide and cytokine production as a response to lipopolysaccharide stimulation. Also, in silico studies on two bile acid-activated receptors were conducted and the results were related to the observed in vitro effects. All tested BAD exerted significant toxicity in concentrations higher than 10 μM, which was determined based on mitochondria and cell membrane damage in a panel of assays. On the other hand, at lower concentrations, the tested BAD proved to be immunomodulatory since they affected lysosomal function, cell adhesion capacities and the ability to produce inflammatory cytokines in response to a stimulus. One of the compounds proved to exhibit significant toxicity toward macrophages, but also caused a concentration-dependent decrease in nitric oxide levels and was identified as a potential farnesoid X receptor agonist.

Targeting extracellular CIRP with an X-aptamer shows therapeutic potential in acute pancreatitis

Severe acute pancreatitis (AP) is associated with a high mortality rate. Cold-inducible RNA binding protein (CIRP) can be released from cells in inflammatory conditions and extracellular CIRP acts as a damage-associated molecular pattern. This study aims to explore the role of CIRP in the pathogenesis of AP and evaluate the therapeutic potential of targeting extracellular CIRP with X-aptamers. Our results showed that serum CIRP concentrations were significantly increased in AP mice. Recombinant CIRP triggered mitochondrial injury and ER stress in pancreatic acinar cells. CIRP-/- mice suffered less severe pancreatic injury and inflammatory responses. Using a bead-based X-aptamer library, we identified an X-aptamer that specifically binds to CIRP (XA-CIRP). Structurally, XA-CIRP blocked the interaction between CIRP and TLR4. Functionally, it reduced CIRP-induced pancreatic acinar cell injury in vitro and L-arginine-induced pancreatic injury and inflammation in vivo. Thus, targeting extracellular CIRP with X-aptamers may be a promising strategy to treat AP.

Bile Acids and Microbiota Interplay in Pancreatic Cancer

Evidence suggests the involvement of the microbiota, including oral, intra-tumoral and gut, in pancreatic cancer progression and response to therapy. The gut microbiota modulates the bile acid pool and is associated with maintaining host physiology. Studies have shown that the bile acid/gut microbiota axis is dysregulated in pancreatic cancer. Bile acid receptor expression and bile acid levels are dysregulated in pancreatic cancer as well. Studies have also shown that bile acids can cause pancreatic cell injury and facilitate cancer cell proliferation. The microbiota and its metabolites, including bile acids, are also altered in other conditions considered risk factors for pancreatic cancer development and can alter responses to chemotherapeutic treatments, thus affecting patient outcomes. Altogether, these findings suggest that the gut microbial and/or bile acid profiles could also serve as biomarkers for pancreatic cancer detection. This review will discuss the current knowledge on the interaction between gut microbiota interaction and bile acid metabolism in pancreatic cancer.

Systemic Bile Acids Affect the Severity of Acute Pancreatitis in Mice Depending on Their Hydrophobicity and the Disease Pathogenesis

Acute pancreatitis (AP) is a major, globally increasing gastrointestinal disease and a biliary origin is the most common cause. However, the effects of bile acids (BAs), given systemically, on the pancreas and on disease severity remains elusive. In this study, we have investigated the roles of different circulating BAs in animal models for AP to elucidate their impact on disease severity and the underlying pathomechanisms. BAs were incubated on isolated acini and AP was induced through repetitive injections of caerulein or L-arginine; pancreatic duct ligation (PDL); or combined biliopancreatic duct ligation (BPDL). Disease severity was assessed using biochemical and histological parameters. Serum cholecystokinin (CCK) concentrations were determined via enzyme immunoassay. The binding of the CCK1 receptor was measured using fluorescence-labeled CCK. In isolated acini, hydrophobic BAs mitigated the damaging effects of CCK. The same BAs further enhanced pancreatitis in L-arginine- and PDL-based pancreatitis, whereas they ameliorated pancreatic damage in the caerulein and BPDL models. Mechanistically, the binding affinity of the CCK1 receptor was significantly reduced by hydrophobic BAs. The hydrophobicity of BAs and the involvement of CCK seem to be relevant in the course of AP. Systemic BAs may affect the severity of AP by interfering with the CCK1 receptor.

The association between parenteral nutrition and pancreatic injury in adult patients: a retrospective observational study

BACKGROUND AND OBJECTIVE

Patients on parenteral nutrition (PN) are at high risk of both liver and pancreatic injury. More efforts were focused on liver, however, limited data is available to evaluate the effects of PN on pancreas. Thus, we performed a retrospective observational study to evaluate the association between PN and pancreatic injury in Chinese adult patients.

METHODS

Adult patients (18-80 years), who received PN for a week or longer, and with repeated measurements of pancreatic enzymes, were included in the analysis. Pancreatic injury was confirmed by serum level of pancreatic amylase (P-AMYwas 53 U/L or higher) or lipase (LP was 63 U/L or higher), which were evaluated at baseline and following every week during PN duration. Age, sex, body weight, height, diagnosis of diseases, history of diseases, surgery, white blood cell, c-reactive protein, liver and renal function, fasting blood glucose, lipid profile, and daily energy supplied by PN and enteral nutrition were abstracted from medical records.

RESULTS

A total number of 190 adult patients (125 men, 65 women) were included in the study. The average age and BMI were 61.8 ± 13.0 years and 21.7±3.3 kg/m2, while medium serum level of P-AMY and LP were 29.0 U/L (quartile range: 18.0, 47.0) and 33.0 U/L (quartile range: 19.0, 58.0), respectively at baseline. The median duration of PN was 15 days (quartile range: 11.0, 21.0). The prevalence of pancreatic injury was 42.1% (80/190) while it was 28.4% (54/190), 43.3% (77/178), 47.8% (44/92) after one-, two-, and three-week or longer PN adminstration. The proportion of daily energy supplement by PN (OR = 3.77, 95%CI: 1.87, 7.61) and history of infection were positively (OR = 3.00, 95%CI: 1.23, 7.36), while disease history for diabetes mellitus (OR = 0.38, 95%CI: 0.15, 0.98) and cancer (OR = 0.46, 95%CI: 0.23, 0.95), were negetively associated with pancreatic injury. Total bile acids were associated with the increment of P-AMY (beta = 0.98, 95%CI: 0.39, 1.56) and LP (beta = 2.55, 95%CI: 0.98, 4.12) by multi-variate linear regression.

CONCLUSION

PN was associated with pancreatic injury, as demonstrated by the increase of both serum P-AMY and LP.

Investigation of the potential role of TGR5 in pancreatic cancer by a comprehensive molecular experiments and the liquid chromatography mass spectrometry (LC-MS) based metabolomics

BACKGROUND

Takeda G protein receptor 5 (TGR5) is widely recognized as a potential drug target for the treatment of metabolic diseases. TGR5 is not only a metabolic regulator, but also has a potential role that participating in developing and progressing of gastrointestinal cancer. We aimed to investigate the potential role of TGR5 in pancreatic cancer by utilizing molecular experiments and the liquid chromatography mass spectrometry (LC-MS) based metabolomics.

METHODS

Herein, we assessed pancreatic cancer proliferation, migration and invasion in response to TGR5 antagonist SBI-115 in vitro experiments. Cell death was examined by using TUNEL assay on agarose-embedded sections. Then we investigated the effects of TGR5 on PANC-1 and BXPC3 cells via transmission electron microscopy (TEM). Moreover, LC-MS-based metabolomics was performed to explore the potential underlying mechanisms of TGR5 in pancreatic cancer. The correlations between TGR5 and the metabolism-related genes were further analysed by GEPIA 2 database.

RESULTS

We found the proliferation capacities were decreased significantly in PANC-1 and BXPC3 cells after the treatment of SBI-115 for 48 h. The results of TUNEL assay showed that antagonism of TGR5 by SBI-115 had a remarkable effect on inducing cell death. Analysis of TEM demonstrated that SBI-115 treatment could impair the morphology of mitochondria in most PANC-1 and BXPC3 cells. The LC-MS-based analyses revealed that antagonism of TGR5 could alter the metabolic profiles of PANC-1 cells in vitro. Moreover, TGR5 was associated with some metabolism-related genes in pancreatic cancer.

CONCLUSION

Our data suggests that antagonism of TGR5 may suppress cell proliferation and induce apoptosis in pancreatic cancer cells. TGR5 may affect the metabolism of pancreatic cancer, and TGR5 would be an attractive target for pancreatic cancer treatment.

The roles of calcium and ATP in the physiology and pathology of the exocrine pancreas

This review deals with the roles of calcium ions and ATP in the control of the normal functions of the different cell types in the exocrine pancreas as well as the roles of these molecules in the pathophysiology of acute pancreatitis. Repetitive rises in the local cytosolic calcium ion concentration in the apical part of the acinar cells not only activate exocytosis but also, via an increase in the intramitochondrial calcium ion concentration, stimulate the ATP formation that is needed to fuel the energy-requiring secretion process. However, intracellular calcium overload, resulting in a global sustained elevation of the cytosolic calcium ion concentration, has the opposite effect of decreasing mitochondrial ATP production, and this initiates processes that lead to necrosis. In the last few years it has become possible to image calcium signaling events simultaneously in acinar, stellate, and immune cells in intact lobules of the exocrine pancreas. This has disclosed processes by which these cells interact with each other, particularly in relation to the initiation and development of acute pancreatitis. By unraveling the molecular mechanisms underlying this disease, several promising therapeutic intervention sites have been identified. This provides hope that we may soon be able to effectively treat this often fatal disease.