C/EBP homologous protein deficiency aggravates acute pancreatitis and associated lung injury

Misfolding-induced chronic pancreatitis in CPA1 N256K mutant mice is unaffected by global deletion of Ddit3/Chop

Genetic mutations in pancreatic digestive enzymes may cause protein misfolding, endoplasmic reticulum (ER) stress and chronic pancreatitis. The CPA1 N256K mouse model carries the human p.N256K carboxypeptidase A1 (CPA1) mutation, a classic example of a pancreatitis-associated misfolding variant. CPA1 N256K mice develop spontaneous, progressive chronic pancreatitis with moderate acinar atrophy, acinar-to-ductal metaplasia, fibrosis, and macrophage infiltration. Upregulation of the ER-stress associated pro-apoptotic transcription factor Ddit3/Chop mRNA was observed in the pancreas of CPA1 N256K mice suggesting that acinar cell death might be mediated through this mechanism. Here, we crossed the CPA1 N256K strain with mice containing a global deletion of the Ddit3/Chop gene (Ddit3-KO mice) and evaluated the effect of DDIT3/CHOP deficiency on the course of chronic pancreatitis. Surprisingly, CPA1 N256K x Ddit3-KO mice developed chronic pancreatitis with a similar time course and features as the CPA1 N256K parent strain. In contrast, Ddit3-KO mice showed no pancreas pathology. The observations indicate that DDIT3/CHOP plays no significant role in the development of misfolding-induced chronic pancreatitis in CPA1 N256K mice and this transcription factor is not a viable target for therapeutic intervention in this disease.

The unfolded protein response: An emerging therapeutic target for pancreatitis and pancreatic ductal adenocarcinoma

Pancreatitis is a debilitating disease involving inflammation and fibrosis of the exocrine pancreas. Recurrent or chronic forms of pancreatitis are a significant risk factor for pancreatic ductal adenocarcinoma. While genetic factors have been identified for both pathologies, environmental stresses play a large role in their etiology. All cells have adapted mechanisms to handle acute environmental stress that alters energy demands. A common pathway involved in the stress response involves endoplasmic reticulum stress and the unfolded protein response (UPR). While rapidly activated by many external stressors, in the pancreas the UPR plays a fundamental biological role, likely due to the high protein demands in acinar cells. Despite this, increased UPR activity is observed in response to acute injury or following exposure to risk factors associated with pancreatitis and pancreatic cancer. Studies in animal and cell cultures models show the importance of affecting the UPR in the context of both diseases, and inhibitors have been developed for several specific mediators of the UPR. Given the importance of the UPR to normal acinar cell function, efforts to affect the UPR in the context of disease must be able to specifically target pathology vs. physiology. In this review, we highlight the importance of the UPR to normal and pathological conditions of the exocrine pancreas. We discuss recent studies suggesting the UPR may be involved in the initiation and progression of pancreatitis and PDAC, as well as contributing to chemoresistance that occurs in pancreatic cancer. Finally, we discuss the potential of targeting the UPR for treatment.

Oroxylin A alleviates immunoparalysis of CLP mice by degrading CHOP through interacting with FBXO15

Clinical reports have found that with the improvement of treatment, most septic patients are able to survive the severe systemic inflammatory response and to enter the immunoparalysis stage. Considering that immunoparalysis leads to numerous deaths of clinical sepsis patients, alleviation of the occurrence and development of immunoparalysis has become a top priority in the treatment of sepsis. In our study, we investigate the effects of oroxylin A on sepsis in cecal ligation and puncture (CLP) mice. We find that the 60 h + 84 h (30 mg/kg) injection scheme of oroxylin A induce the production of pro-inflammatory factors, and further significantly improves the survival of CLP mice during the middle or late stages of sepsis. Mechanistically, C/EBP-homologous protein (CHOP) is upregulated and plays anti-inflammatory roles to facilitate the development of immunoparalysis in CLP mice. Oroxylin A induces the transcription of E3 ligase F-box only protein 15 gene (fbxo15), and activated FBXO15 protein binds to CHOP and further mediates the degradation of CHOP through the proteasome pathway, which eventually relieves the immunoparalysis of CLP mice. Taken together, these findings suggest oroxylin A relieves the immunoparalysis of CLP mice by degrading CHOP through interacting with FBXO15.

Murine Models of Acute Pancreatitis: A Critical Appraisal of Clinical Relevance

Acute pancreatitis (AP) is a severe disease associated with high morbidity and mortality. Clinical studies can provide some data concerning the etiology, pathophysiology, and outcomes of this disease. However, the study of early events and new targeted therapies cannot be performed on humans due to ethical reasons. Experimental murine models can be used in the understanding of the pancreatic inflammation, because they are able to closely mimic the main features of human AP, namely their histologic glandular changes and distant organ failure. These models continue to be important research tools for the reproduction of the etiological, environmental, and genetic factors associated with the pathogenesis of this inflammatory pathology and the exploration of novel therapeutic options. This review provides an overview of several murine models of AP. Furthermore, special focus is made on the most frequently carried out models, the protocols used, and their advantages and limitations. Finally, examples are provided of the use of these models to improve knowledge of the mechanisms involved in the pathogenesis, identify new biomarkers of severity, and develop new targeted therapies.

Acinar cell injury induced by inadequate unfolded protein response in acute pancreatitis

Acute pancreatitis (AP) is an inflammatory disorder of pancreatic tissue initiated in injured acinar cells. Severe AP remains a significant challenge due to the lack of effective treatment. The widely-accepted autodigestion theory of AP is now facing challenges, since inhibiting protease activation has negligible effectiveness for AP treatment despite numerous efforts. Furthermore, accumulating evidence supports a new concept that malfunction of a self-protective mechanism, the unfolded protein response (UPR), is the driving force behind the pathogenesis of AP. The UPR is induced by endoplasmic reticulum (ER) stress, a disturbance frequently found in acinar cells, to prevent the aggravation of ER stress that can otherwise lead to cell injury. In addition, the UPR’s signaling pathways control NFκB activation and autophagy flux, and these dysregulations cause acinar cell inflammatory injury in AP, but with poorly understood mechanisms. We therefore summarize the protective role of the UPR in AP, propose mechanistic models of how inadequate UPR could promote NFκB’s pro-inflammatory activity and impair autophagy’s protective function in acinar cells, and discuss its relevance to current AP treatment. We hope that insight provided in this review will help facilitate the research and management of AP.

Effects of Toll‑like receptor 9 and CpG oligodeoxynucleotides 1826 on sodium taurocholate‑induced acute pancreatitis rats

The aim of the present study was to investigate the effects of Toll-like receptor (TLR) 9 and CpG oligodeoxynucleotide (CpG-ODN)1826 on sodium taurocholate-induced acute pancreatitis (AP) rats at different time points. Pathological examination indicated that the severity of pancreatic tissue damage following AP increased with time. Additionally, TLR9 protein levels were upregulated after AP, and were higher at 6 h compared with at 3 h. Subsequently, the TLR9 protein levels were downregulated at 12 h, but remained higher than the control group. In rats subjected to AP, tumor necrosis factor (TNF-α protein expression levels and serum amylase (AMS) in the serum were increased until 12 h. The expression level of TNF-α protein in the AP 12 h group was higher than that in the AP 3 and 6 h groups. In addition, following CpG-ODN1826 administration, the morphology of pancreatic tissue appeared worse compared with that in the AP only groups. Furthermore, CpG-ODN1826 administration induced an increase in TLR9 expression levels compared with the AP alone group at 0, 3, 6 and 12 h. TNF-α in the CpG + AP 12 h group was upregulated compared with that in the CpG + AP 3 and 6 h groups; however, no change was observed between 3 and 6 h. Thus, these data indicate that CpG-ODN1826 aggravates sodium taurocholate-induced pancreas damage in rats.

Gadd153 deficiency attenuates abdominal aortic aneurysm formation in mice

Abdominal aortic aneurysms (AAAs) are a chronic inflammatory vascular disease for which pharmacological treatments are not available. Gadd153 is closely associated with the onset of vascular smooth muscle cells (VSMCs) apoptosis. However, a role for Gadd153 in AngII-induced AAA formation is currently unknown. In our study, lentiviral-mediated silencing of Gadd153 through small RNA interference was performed in mice, which was further used for the establishment of mouse experimental AAA induced by infusion of angiotensin II (AngII). We found that Gadd153 deficiency prevented AngII-induced AAA formation in mice 14 days post perfusion compared with wild-type control mice. Moreover, Gadd153 deficiency significantly reduced lesion macrophage and CD4+ T-cell content, T-cell proliferation, SMC apoptosis, and matrix metalloproteinase expression. In vitro studies revealed that Gadd153 deficiency regulated microvessel growth and monocyte migration. In addition, Gadd153 deficiency also affected AAA lesion Mac-3 macrophage accumulation or CD31 microvessel numbers. In conclusion, our study demonstrates that Gadd153 plays an essential role in AngII-induced AAA formation by promoting inflammatory cells proliferation and vascular SMC apoptosis affecting MMPs expression.

Indomethacin inhabits the NLRP3 inflammasome pathway and protects severe acute pancreatitis in mice

Clinical studies have confirmed that indomethacin (Indo) can reduce the incidence and severity of post-endoscopicretrogradecholangio-pancreatography pancreatitis (PEP) effectively. However, the role of Indo on severe acute pancreatitis (SAP) is not clear. In the present study, we aimed to explore the effects of Indo treatment on SAP model induced by caerulein combined with lipopolysaccharide. After intraperitoneal injection of Indo in mice, both the severity of SAP and the serum levels of amylase, lipase, and proinflammatory cytokines were decreased. Furthermore, the mRNA and protein levels of NLRP3 inflammasome pathway (NLRP3,ASC and IL-1β) in pancreatic tissues were down-regulated. In vitro experiments, by isolating the pancreatic acinar cells (PACs) from mice, we found that Indo significantly reduced lactate dehydrogenase(LDH) excretion, increased the cell activity, and inhibited the NLRP3 inflammasome pathway of PACs. Taken together, our data showed that Indo could protect pancreatic acinar cell from injury by inhabiting NLRP3 pathway and decreased the severity of SAP accordingly.

Study on acute recent stage pancreatitis

Acute pancreatitis (AP) is an inflammatory disease of the pancreas which involves the pancreas and surrounding tissue, and systemic inflammation with a characteristic systemic increase of vascular permeability and increased risk of multiple organ dysfunction. Currently, the pathogenesis of AP is fuzzy, and the diagnosis and treatment need to be standardized. Nevertheless, increased knowledge of AP may achieve more thorough understanding of the pathogenesis. The use of further advanced diagnostic tools and superior treatment, potentially will help clinicians to manage AP at an appropriate stage. However, in view of the multi factorial disease and the complex clinical manifestations, the management of patients with AP is also remaining areas for improvement.