Protective Effects of Lithospermum erythrorhizon Against Cerulein-Induced Acute Pancreatitis

Ehmt2 inactivation in pancreatic epithelial cells shapes the transcriptional landscape and inflammation response of the whole pancreas

Introduction: The Euchromatic Histone Methyl Transferase Protein 2 (EHMT2), also known as G9a, deposits transcriptionally repressive chromatin marks that play pivotal roles in the maturation and homeostasis of multiple organs. Recently, we have shown that Ehmt2 inactivation in the mouse pancreas alters growth and immune gene expression networks, antagonizing Kras-mediated pancreatic cancer initiation and promotion. Here, we elucidate the essential role of Ehmt2 in maintaining a transcriptional landscape that protects organs from inflammation. Methods: Comparative RNA-seq studies between normal postnatal and young adult pancreatic tissue from Ehmt2 conditional knockout animals (Ehmt2 fl/fl ) targeted to the exocrine pancreatic epithelial cells (Pdx1-Cre and P48 Cre/+ ), reveal alterations in gene expression networks in the whole organ related to injury-inflammation-repair, suggesting an increased predisposition to damage. Thus, we induced an inflammation repair response in the Ehmt2 fl/fl pancreas and used a data science-based approach to integrate RNA-seq-derived pathways and networks, deconvolution digital cytology, and spatial transcriptomics. We also analyzed the tissue response to damage at the morphological, biochemical, and molecular pathology levels. Results and discussion: The Ehmt2 fl/fl pancreas displays an enhanced injury-inflammation-repair response, offering insights into fundamental molecular and cellular mechanisms involved in this process. More importantly, these data show that conditional Ehmt2 inactivation in exocrine cells reprograms the local environment to recruit mesenchymal and immunological cells needed to mount an increased inflammatory response. Mechanistically, this response is an enhanced injury-inflammation-repair reaction with a small contribution of specific Ehmt2-regulated transcripts. Thus, this new knowledge extends the mechanisms underlying the role of the Ehmt2-mediated pathway in suppressing pancreatic cancer initiation and modulating inflammatory pancreatic diseases.

Protective effects of Coenzyme Q10 against acute pancreatitis

Acute pancreatitis (AP) refers to inflammation in the pancreas, which may lead to death in severe cases. Coenzyme Q10 (Q10), generally known to generate energy, plays an important role as an anti-oxidant and anti-inflammatory effector. Here, we showed the effect of Q10 on inflammatory response in murine AP model. For this study, we induced AP by injection of cerulein intraperitoneally or pancreatic duct ligation (PDL) in mice. The level of cytokines and digestive enzymes were measured in pancreas, and blood. All pancreatic tissues were excised for investigation such as histological changes, infiltration of immune cells. Administration of Q10 attenuated the severity of AP and its associated pulmonary complication as shown by reduction of acinar cell death, parenchymal edema, inflammatory cell infiltration and alveolar thickening in both cerulein-induced AP and PDL-induced AP. Moreover, reduction of the cytokines such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α were observed in pancreas and pancreatic acinar cells by Q10. Furthermore, Q10 reduced the infiltration of immune cells such as monocytes and neutrophils and augmentation of chemokines such as CC chemokine-2 (CCL2) and C-X-C chemokine-2 (CXCL2) in pancreas of AP mice. In addition, Q10 deactivates the phosphorylation of extracellular signal-regulated kinase (ERK) and c-jun NH₂-terminal kinase (JNK) in pancreas. In conclusion, these observations suggest that Q10 could attenuate the pancreatic damage and its associated pulmonary complications via inhibition of inflammatory cytokines and inflammatory cell infiltration and that the deactivation of ERK and JNK by Q10 might contribute to the attenuation of AP.

Ceruloplasmin and hephaestin jointly protect the exocrine pancreas against oxidative damage by facilitating iron efflux

Little is known about the iron efflux from the pancreas, but it is likely that multicopper ferroxidases (MCFs) are involved in this process. We thus used hephaestin (Heph) and ceruloplasmin (Cp) single-knockout mice and Heph/Cp double-knockout mice to investigate the roles of MCFs in pancreatic iron homeostasis. We found that both HEPH and CP were expressed in the mouse pancreas, and that ablation of either MCF had limited effect on the pancreatic iron levels. However, ablation of both MCFs together led to extensive pancreatic iron deposition and severe oxidative damage. Perls’ Prussian blue staining revealed that this iron deposition was predominantly in the exocrine pancreas, while the islets were spared. Consistent with these results, plasma lipase and trypsin were elevated in Heph/Cp knockout mice, indicating damage to the exocrine pancreas, while insulin secretion was not affected. These data indicate that HEPH and CP play mutually compensatory roles in facilitating iron efflux from the exocrine pancreas, and show that MCFs are able to protect the pancreas against iron-induced oxidative damage.

Melatonin attenuated inflammatory reaction by inhibiting the activation of p38 and NF‑κB in taurocholate‑induced acute pancreatitis

The aim of the present study was to investigate the protective mechanism underlying of melatonin in severe acute pancreatitis (SAP). A total of 64 male Sprague‑Dawley rats were randomly divided into four groups: The sham operation (SO) group, SAP group, melatonin treatment (MLT) group and p38 inhibitor (SB203580) treatment (SB) group. Acute pancreatitis was induced by 5% taurocholate through retrograde infusion into the biliopancreatic ducts. The melatonin and SB203580 treatment groups were administered with MLT and SB 30 min before operation the induction of SAP. Rats in each group were euthanized at 6 and 12 h following SAP induction. Blood and pancreatic tissues were removed for inflammatory examination. Peripheral blood mononuclear cells (PBMCs) were isolated following sacrifice to measure the phosphorylation of p38 and nuclear factor‑κB (NF‑κB was measured as p65 and phosphorylation of p65). The pretreatment of melatonin significantly attenuated the severity of pancreatitis. In addition, melatonin also reduced serum amylase and proinflammatory cytokine levels, including tumor necrosis factor‑α, interleukin (IL)‑1 and IL‑6. The mean pathological scores for pancreatic tissues in the MLT group were higher than those for samples in the SO group, but were lower than those for samples in the SAP group at each time-point. Phosphorylation of p38 and p65 levels in the melatonin treatment group were lower than that in the SAP group, and higher in the SAP group than in the SO group, and the SB203580 treatment group. Furthermore, melatonin significantly inhibited the activation of p38 and NF‑κB in PBMCs. The authors revealed that melatonin may attenuate inflammatory reactions by inhibiting the activation of p38 MAPK and NF‑κB in both acute pancreatitis rats and PBMCs. SAP is a severe disease with a high risk of morbidity and mortality. It is important to attenuated inflammatory reaction in acute pancreatitis. Thus, the authors studied melatonin, which is synthesized by the pineal gland and released into the blood. Previous studies have shown that melatonin serves a protective role in the early course of human acute pancreatitis, and melatonin concentration variations are closely related to the severity of acute pancreatitis. It may be concluded that melatonin may attenuates inflammatory reactions by inhibiting the activation of p38 MAPK and NF‑κB in both acute pancreatitis rats and PBMCs.

Differential susceptibility of mouse strains on pancreatic injury and regeneration in cerulein-induced pancreatitis

Acute pancreatitis (AP), a common disease, causes significant morbidity and mortality in clinical practice. Our objective of this study was to establish an experimental mouse AP model with cerulein treatment and to explore the susceptibility of mouse strains on the severity of pancreatic injury and the subsequent repair and regeneration. C57BL/6 and FVB/N mouse strains were used in this study. AP model was induced by six hourly intraperitoneal (i.p.) injections of cerulein dissolved in saline (100 μg/kg) administered on four consecutive days. Animals were sacrificed on 1, 3 and 7 days after last cerulein treatment, and then pancreas tissues were harvested and subjected to various histological, cellular and molecular analysis. Analyses of pancreatic injury and pancreatic amylase expression indicated that this cerulein-induced AP model was established successfully and that FVB/N mice showed more severe pancreatic injury and poor recovery compared to C57BL/6 strain. Analyses of myeloperoxidase (MPO), IL-1β and NF-κB showed that FVB/N strain exhibited more severe inflammation in the pancreas compared to C57BL/6 mice. Immunofluorescence analysis of activated caspase-3 and TUNEL assay indicated that the pancreas of FVB/N strain had more apoptosis compared to C57BL/6 mice. Analysis of Ki67 indicated FVB/N mice experienced more active proliferation compared to C57BL/6 strain. Collectively, these results demonstrated that there exists differential susceptibility on pancreatic injury and regeneration between FVB/N and C57BL/6 mice in the cerulein-induced AP.

Therapeutic implications of innate immune system in acute pancreatitis

INTRODUCTION

Acute pancreatitis (AP) is an inflammatory disorder of the pancreas encompassing a cascade of cellular and molecular events. It starts from premature activation of zymogens with the involvement of innate immune system to a potential systemic inflammatory response and multiple organ failure. Leukocytes are the major cell population that participate in the propagation of the disease. Current understanding of the course of AP is still far from complete, limiting treatment options mostly to conservative supportive care. Emerging evidence has pointed to modulation of the immune system for strategic therapeutic development, by mitigating the inflammatory response and severity of AP. In the current review, we have focused on the role of innate immunity in the condition and highlighted therapeutics targeting it for treatment of this challenging disease.

AREAS COVERED

The current review has aimed to elaborate in-depth understanding of specific roles of innate immune cells, derived mediators and inflammatory pathways that are involved in AP. Summarizing the recent therapeutics and approaches applied experimentally that target immune responses to attenuate AP.

EXPERT OPINION

The current state of knowledge on AP, limitations of presently available therapeutic approaches and the promise of therapeutic implications of innate immune system in AP are discussed.