Evaluation of secretory activity in carp pancreatocytes (Cyprinus carpio L.) when using lactobacillus-based chelate and probiotic supplemental feed complexes

The experimental research was carried out on the juvenile carp (Cyprinus carpio L.). The impact from supplemental feeds consisting of variable concentrations of chelate compounds, biogenic trace elements and probiotic lactobacillus-based product Bacillus subtilis VKPM B-2335 was evaluated. Optical and qualitative parameters of the lactobacillus base were studied in order to identify the major group of substances potentially able to influence the end result. The purpose of this research was to identify changes in the structure of the zymogen granules and their dimensions at which supplemental feeds produce a stimulating effect on the synthesis of zymogens in exogenous cells of the secretory part of pancreas. At the outcome of the study, for the first time, it was possible to prove that the integrated action of chelates and lactobacillus-based probiotics complemented each other. Metal chelate compounds contributed to enlargement of the zymogen granules, if compared to the control values. The bacterial products accelerated production of the zymogen granules in acinar cells diffusely located in carp hepatopancreas.

A Severe Acute Pancreatitis Mouse Model Transited from Mild Symptoms Induced by a “Two-Hit” Strategy with L-Arginine

To develop a severe acute pancreatitis (SAP) model transited from mild symptoms, we investigated a “two-hit” strategy with L-arginine in mice. The mice were intraperitoneally injected with ice-cold L-arginine (4 g/kg) twice at an interval of 1 h on the first day and subjected to the repeated operation 72 h afterwards. The results showed the “two-hit” strategy resulted in the destructive damage and extensive necrosis of acinar cells in the pancreas compared with the “one-hit” model. Meanwhile, excessive levels of pro-inflammatory mediators, namely IL-6 and TNF-α, were released in the serum. Remarkably, additional deleterious effects on multiple organs were observed, including high intestinal permeability, kidney injury, and severe acute lung injury. Therefore, we confirmed that the SAP animal model triggered by a “two-hit” strategy with L-arginine was successfully established, providing a solid foundation for a deeper understanding of SAP initiation and therapy research to prevent worsening of the disease.

MFG-E8 Maintains Cellular Homeostasis by Suppressing Endoplasmic Reticulum Stress in Pancreatic Exocrine Acinar Cells

Excessive endoplasmic reticulum (ER) stress contributes significantly to the pathogenesis of exocrine acinar damage in acute pancreatitis. Our previous study found that milk fat globule EGF factor 8 (MFG-E8), a lipophilic glycoprotein, alleviates acinar cell damage during AP via binding to αvβ3/5 integrins. Ligand-dependent integrin-FAK activation of STAT3 was reported to be of great importance for maintaining cellular homeostasis. However, MFG-E8’s role in ER stress in pancreatic exocrine acinar cells has not been evaluated. To study this, thapsigargin, brefeldin A, tunicamycin and cerulein + LPS were used to induce ER stress in rat pancreatic acinar cells in vitro. L-arginine- and cerulein + LPS-induced acute pancreatitis in mice were used to study ER stress in vivo. The results showed that MFG-E8 dose-dependently inhibited ER stress under both in vitro and in vivo conditions. MFG-E8 knockout mice suffered more severe ER stress and greater inflammatory response after L-arginine administration. Mechanistically, MFG-E8 increased phosphorylation of FAK and STAT3 in cerulein + LPS-treated pancreatic acinar cells. The presence of specific inhibitors of αvβ3/5 integrin, FAK or STAT3 abolished MFG-E8’s effect on cerulein + LPS-induced ER stress in pancreatic acinar cells. In conclusion, MFG-E8 maintains cellular homeostasis by alleviating ER stress in pancreatic exocrine acinar cells.

IRAG2 Interacts with IP3-Receptor Types 1, 2, and 3 and Regulates Intracellular Ca2+ in Murine Pancreatic Acinar Cells

The inositol 1,4,5-triphosphate receptor-associated 2 (IRAG2) is also known as Jaw1 or lymphoid-restricted membrane protein (LRMP) and shares homology with the inositol 1,4,5-triphosphate receptor-associated cGMP kinase substrate 1 (IRAG1). IRAG1 interacts with inositol trisphosphate receptors (IP3 receptors /IP3R) via its coiled-coil domain and modulates Ca2+ release from intracellular stores. Due to the homology of IRAG1 and IRAG2, especially in its coiled-coil domain, it is possible that IRAG2 has similar interaction partners like IRAG1 and that IRAG2 also modulates intracellular Ca2+ signaling. In our study, we localized IRAG2 in pancreatic acinar cells of the exocrine pancreas, and we investigated the interaction of IRAG2 with IP3 receptors and its impact on intracellular Ca2+ signaling and exocrine pancreatic function, like amylase secretion. We detected the interaction of IRAG2 with different subtypes of IP3R and altered Ca2+ release in pancreatic acinar cells from mice lacking IRAG2. IRAG2 deficiency decreased basal levels of intracellular Ca2+, suggesting that IRAG2 leads to activation of IP3R under unstimulated basal conditions. Moreover, we observed that loss of IRAG2 impacts the secretion of amylase. Our data, therefore, suggest that IRAG2 modulates intracellular Ca2+ signaling, which regulates exocrine pancreatic function.

Glycoprotein 2 in health and disease: lifting the veil

In 2020, we discovered glycoprotein 2 (GP2) variants associated with pancreatic cancer susceptibility in a genome-wide association study involving the Japanese population. Individuals carrying a missense coding variant (rs78193826) in the GP2 gene resulting in a p.V432M substitution had an approximately 1.5-fold higher risk of developing pancreatic cancer than those without this variant. GP2 is expressed on the inner surface of zymogen granules in pancreatic acinar cells, which are responsible for the sorting, storage and secretion of digestive enzymes. Upon neuronal, hormonal, or other stimulation, GP2 is cleaved from the membrane of zymogen granules and then secreted into the pancreatic duct and intestinal lumen. While the functions of GP2 remain poorly understood, emerging evidence suggests that it plays an antibacterial role in the gastrointestinal tract after being secreted from pancreatic acinar cells. Impaired GP2 functions may facilitate the adhesion of bacteria to the intestinal mucosa. In this review article, we summarize the role of GP2 in health and disease, emphasizing its functions in the gastrointestinal tract, as well as genetic variations in the GP2 gene and their associations with disease susceptibility. We hope that its robust genetic associations with pancreatic cancer, coupled with its emerging role in gastrointestinal mucosal immunity, will spur renewed research interest in GP2, which has been understudied over the past 30 years compared with its paralog uromodulin (UMOD).

Counter effects of Vitamin E against Outcomes of Alcohol Toxicity in Pancreatic Acini: Histomorphometric Study

Aim: To evaluate the effects of alcohol on the microscopic morphology of the exocrine pancreas and blood serum amylase and to explored that if vitamin E has a protective role against alcohol-induced damage in the pancreas of rabbits. Study design: Analytical experimental study Place and duration of study: Departments of Anatomy, Pathology and Pharmacology in Peshawar Medical College Pakistan from 1st January 2019 to 30th June 2019. Methodology: Eighteen healthy adult male domestic rabbits weighing 1-1.5 kg were chosen (oryctolaguscuniculus). The control group A received proper food and normal saline as drinking water, experimental group B received proper diet and 30 percent ethanol solution (30ml/kg/day) orally daily with normal saline, and experimental group C received proper diet, 30 percent ethanol solution (30ml/kg/day), vitamin E (50mg/kg/day) orally daily with normal saline. Each rabbit's blood was taken for serum amylase. Morphology of acinar cells included: 1) number of cells, (10 acini/field, 2) size of acini, 3) size of acinar cells, and 4) size of acinar nuclei. Results: Normal value of serum amylase in rabbits was found. The difference in serum amylase levels between the control and experimental groups for both E4 and E8 animals was not statistically significant. There was no significant difference in the number of pancreatic acinar cells, size of pancreatic acini, the pancreatic acinar cell size, and pancreatic acinar cells nuclear size in the control and experimental groups for both E4 and E8 animals. Conclusion: Alcohol consumption had no influence on the histomorphology of the rabbits' pancreatic acini in a short period (4-8 weeks). No significant variation was noted in the pancreatic acinar cells count & size, pancreatic acinar cells nuclear count and size, and pancreatic acini size. Therefore, protective role of vitamin E was not usefully identified. Keywords: Alcohol, Pancreas, Histomorphology, Vitamin E, Serum amylase

CaMK II Inhibition Attenuates ROS Dependent Necroptosis in Acinar Cells and Protects against Acute Pancreatitis in Mice

As a calcium-regulated protein, CaMK II is closely related to cell death, and it participates in the development of pathological processes such as reperfusion injury, myocardial infarction, and oligodendrocyte death. The function of CaMK II activation in acute pancreatitis (AP) remains unclear. In our study, we confirmed that the expression of p-CaMK II was increased significantly and consistently in injured pancreatic tissues after caerulein-induced AP. Then, we found that KN93, an inhibitor of CaMK II, could mitigate the histopathological manifestations in pancreatic tissues, reduce serum levels of enzymology, and decrease oxidative stress products. Accordingly, we elucidated the effect of KN93 in vitro and found that KN93 had a protective effect on the pancreatic acinar cell necroptosis pathway by inhibiting the production of ROS and decreasing the expression of RIP3 and p-MLKL. In addition, we identified the protective effect of KN93 on AP through another mouse model induced by pancreatic duct ligation (PDL). Together, these data demonstrated that CaMK II participates in the development of AP and that inhibiting CaMK II activation could protect against AP by reducing acinar cell necroptosis, which may provide a new idea target for the prevention and treatment of AP in the clinic.

Saikosaponin D Attenuates Pancreatic Injury Through Suppressing the Apoptosis of Acinar Cell via Modulation of the MAPK Signaling Pathway

Chronic pancreatitis (CP) is a progressive fibro-inflammatory syndrome. The damage of acinar cells is the main cause of inflammation and the activation of pancreatic stellate cells (PSCs), which can thereby possibly further aggravate the apoptosis of more acinar cells. Saikosaponind (SSd), a major active ingredient derived from Chinese medicinal herb bupleurum falcatum, which exerted multiple pharmacological effects. However, it is not clear whether SSd protects pancreatic injury of CP via regulating the apoptosis of pancreatic acinar cells. This study systematically investigated the effect of SSd on pancreatic injury of CP in vivo and in vitro. The results revealed that SSd attenuate pancreatic damage, decrease the apoptosis and suppress the phosphorylation level of MAPK family proteins (JNK1/2, ERK1/2, and p38 MAPK) significantly in the pancreas of CP rats. In addition, SSd markedly reduced the apoptosis and inflammation of pancreatic acinar AR42J cells induced by cerulein, a drug induced CP, or Conditioned Medium from PSCs (PSCs-CM) or the combination of PSCs-CM and cerulein. Moreover, SSd significantly inhibited the activated phosphorylation of JNK1/2, ERK1/2, and p38 MAPK induced by cerulein or the combination of PSCs-CM and cerulein in AR42J cells. Furthermore, SSd treatment markedly decreased the protein levels of p-JNK and p-p38 MAPK caused by PSCs-CM alone. In conclusion, SSd ameliorated pancreatic injury, suppressed AR42J inflammation and apoptosis induced by cerulein, interrupted the effect of PSCs-CM on AR42J cells inflammation and apoptosis, possibly through MAPK pathway.