Myeloid, but not pancreatic, RelA/p65 is required for fibrosis in a mouse model of chronic pancreatitis

Dysfunctional astrocyte glutamate uptake in the hypothalamic paraventricular nucleus contributes to visceral pain and anxiety-like behavior in mice with chronic pancreatitis

Abdominal visceral pain is a predominant symptom in patients with chronic pancreatitis (CP); however, the underlying mechanism of pain in CP remains elusive. We hypothesized that astrocytes in the hypothalamic paraventricular nucleus (PVH) contribute to CP pain pathogenesis. A mouse model of CP was established by repeated intraperitoneal administration of caerulein to induce abdominal visceral pain. Abdominal mechanical stimulation, open field and elevated plus maze tests were performed to assess visceral pain and anxiety-like behavior. Fiber photometry, brain slice Ca2+ imaging, electrophysiology, and immunohistochemistry were used to investigate the underlying mechanisms. Mice with CP displayed long-term abdominal mechanical allodynia and comorbid anxiety, which was accompanied by astrocyte glial fibrillary acidic protein reactivity, elevated Ca2+ signaling, and astroglial glutamate transporter-1 (GLT-1) deficits in the PVH. Specifically, reducing astrocyte Ca2+ signaling in the PVH via chemogenetics significantly rescued GLT-1 deficits and alleviated mechanical allodynia and anxiety in mice with CP. Furthermore, we found that GLT-1 deficits directly contributed to the hyperexcitability of VGLUT2PVH neurons in mice with CP, and that pharmacological activation of GLT-1 alleviated the hyperexcitability of VGLUT2PVH neurons, abdominal visceral pain, and anxiety in these mice. Taken together, our data suggest that dysfunctional astrocyte glutamate uptake in the PVH contributes to visceral pain and anxiety in mice with CP, highlighting GLT-1 as a potential therapeutic target for chronic pain in patients experiencing CP.

Metformin instigates cellular autophagy to ameliorate high-fat diet-induced pancreatic inflammation and fibrosis/EMT in mice

BACKGROUND

Chronic pancreatic dysfunction is frequently observed as a consequence of prolonged high-fat diet consumption and is a serious public health concern. This pro-diabetic insult aggravates inflammation-influenced fibrotic lesions and is associated with deregulated autophagy. Metformin, a conventional anti-hyperglycemic drug, might be beneficial for pancreatic health, but the complex molecular regulations are not clarified. Considering the worldwide prevalence of chronic pancreatic dysfunction in obese individuals, we aimed to unwind the molecular intricacies explaining the involvement of oxidative stress, inflammation and fibrosis and to approbate metformin as a plausible intervention in this crossroad.

MAIN METHODS

Age-matched Swiss Albino mice were exposed to high-fat diet (60 kcal%) against control diet (10 kcal%) to establish diet-induced stress model. Metformin treatment was introduced after 4 weeks to metformin-control and HFD-exposed metformin groups. After 8 weeks, metabolic and molecular outcomes were assessed to establish the impact of metformin on chronic consequences of HFD-mediated injury.

KEY FINDINGS

High-fat diet administration to healthy mice primes oxidative stress-mediated chronic inflammation through Nrf2/Keap1/NF-κB interplay. Besides, pro-inflammatory cytokine bias leading to fibrotic (increased TGF-β, α-SMA, and MMP9) and pro-EMT (Twist1, Slug, Vimentin, E-cadherin) repercussions in pancreatic lobules were evident. Metformin distinctly rescues high-fat diet-induced remodeling of pancreatic pro-diabetic alterations and cellular survival/death switch. Further, metformin abrogates the p62-Twist1 crosstalk in an autophagy-dependent manner (elevated beclin1, LC3-II/I, Lamp2) to restore pancreatic homeostasis.

CONCLUSION

Our research validates the therapeutic potential of metformin in the inflammation-fibrosis nexus to ameliorate high-fat diet-induced pancreatic dysfunction and related metabolic alterations.

Target NF-κB p65 for preventing posttraumatic joint contracture in rats

RelA/p65 is as a crucial component of the nuclear factor κB (NF-κB) signaling pathway that has a significant impact on various fibrotic diseases. However, its role in the fibrosis of tissues surrounding the joint after traumatic injury remains unclear. In this study, rats were divided into three groups: non-operated control (NC) group, p65-siRNA treated (siRNA-p65) group, and negative siRNA treated (siRNA-neg) group. Then, 10 μL (10 nmol) of p65-siRNA was injected into the joint of the siRNA-p65 group. Meanwhile, 10 μL of negative siRNA was administered to the knee joint of the operated siRNA-neg group for comparison. The rats in the NC group did not receive surgery or drug intervention. After 4 weeks of right knee fixation in each group, X-ray measurements revealed significantly reduced degree of knee flexion contracture following p65-siRNA treatment (siRNA-neg: 77.73° ± 2.799°; siRNA-p65: 105.7° ± 2.629°, p < 0.0001). Histopathological examination revealed that the number of dense fibrous connective tissues decreased following p65-siRNA inhibition. Western blot analysis revealed significantly different expression levels of fibrosis-related proteins between the siRNA-p65 and siRNA-neg groups. Immunohistochemical analysis revealed a reduction in the average number of myofibroblasts in the siRNA-p65 group compared with that in the siRNA-neg group. Thus, intra-articular p65-siRNA injection could attenuate fibroblast activation and fibrosis-related protein production, suppress periarticular tissue fibrosis, and prevent joint contracture by downregulating the NF-κB p65 pathway. Statement of clinical significance: Intra-articular injection of p65-siRNA could reduce myofibroblast proliferation and fibrosis-related protein expression by downregulating the NF-κB p65 pathway, inhibit periarticular tissue fibrosis, and prevent joint adhesion, which represents a potential therapy in the prevention of joint fibrosis following traumatic injury.

Anti-Inflammatory Properties of the Citrus Flavonoid Diosmetin: An Updated Review of Experimental Models

Inflammation is an essential contributor to various human diseases. Diosmetin (3',5,7-trihydroxy-4'-methoxyflavone), a citrus flavonoid, can be used as an anti-inflammatory agent. All the information in this article was collected from various research papers from online scientific databases such as PubMed and Web of Science. These studies have demonstrated that diosmetin can slow down the progression of inflammation by inhibiting the production of inflammatory mediators through modulating related pathways, predominantly the nuclear factor-κB (NF-κB) signaling pathway. In this review, we discuss the anti-inflammatory properties of diosmetin in cellular and animal models of various inflammatory diseases for the first time. We have identified some deficiencies in current research and offer suggestions for further advancement. In conclusion, accumulating evidence so far suggests a very important role for diosmetin in the treatment of various inflammatory disorders and suggests it is a candidate worthy of in-depth investigation.

Acinar cells and the development of pancreatic fibrosis

Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.

Immune cells and immune cell-targeted therapy in chronic pancreatitis

In recent years, studies have attempted to understand the immune cells and mechanisms underlying the pathogenesis of chronic pancreatitis (CP) by constructing a model of CP. Based on these studies, the innate immune response is a key factor in disease pathogenesis and inflammation severity. Novel mechanisms of crosstalk between immune and non-immune pancreatic cells, such as pancreatic stellate cells (PSC), have also been explored. Immune cells, immune responses, and signaling pathways in CP are important factors in the development and progression of pancreatitis. Based on these mechanisms, targeted therapy may provide a feasible scheme to stop or reverse the progression of the disease in the future and provide a new direction for the treatment of CP. This review summarizes the recent advances in research on immune mechanisms in CP and the new advances in treatment based on these mechanisms.

Defining the spatial-molecular map of fibrotic tendon healing and the drivers of Scleraxis-lineage cell fate and function

Tendon injuries heal via a scar-mediated response, and there are no biological approaches to promote more regenerative healing. Mouse flexor tendons heal through the formation of spatially distinct tissue areas: a highly aligned tissue bridge between the native tendon stubs that is enriched for adult Scleraxis-lineage cells and a disorganized outer shell associated with peri-tendinous scar formation. However, the specific molecular programs that underpin these spatially distinct tissue profiles are poorly defined. In the present study, we combine lineage tracing of adult Scleraxis-lineage cells with spatial transcriptomic profiling to define the overarching molecular programs that govern tendon healing and cell-fate decisions. Pseudotime analysis identified three fibroblast trajectories (synthetic, fibrotic, and reactive) and key transcription factors regulating these fate-switching decisions, including the progression of adult Scleraxis-lineage cells through the reactive trajectory. Collectively, this resource defines the molecular mechanisms that coordinate the temporo-spatial healing phenotype, which can be leveraged to inform therapeutic candidate selection.

Understanding Necroptosis in Pancreatic Diseases

Intermediate between apoptosis and necrosis, necroptosis is a regulated caspase-independent programmed cell death that induces an inflammatory response and mediates cancer development. As our understanding improves, its role in the physiopathology of numerous diseases, including pancreatic diseases, has been reconsidered, and especially in pancreatitis and pancreatic cancer. However, the exact pathogenesis remains elusive, even though some studies have been conducted on these diseases. Its unique mechanisms of action in diseases are expected to bring prospects for the treatment of pancreatic diseases. Therefore, it is imperative to further explore its molecular mechanism in pancreatic diseases in order to identify novel therapeutic options. This article introduces recent related research on necroptosis and pancreatic diseases, explores necroptosis-related molecular pathways, and provides a theoretical foundation for new therapeutic targets for pancreatic diseases.

Pirfenidone ameliorates chronic pancreatitis in mouse models through immune and cytokine modulation

Chronic pancreatitis (CP) is an irreversible fibro-inflammatory disease of the pancreas with no current targeted therapy. Pirfenidone, an anti-fibrotic and anti-inflammatory drug, is FDA approved for treatment of Idiopathic Pulmonary Fibrosis (IPF). Its efficacy in ameliorating CP has never been evaluated before. We recently reported that pirfenidone improves acute pancreatitis in mouse models. The aim of the current study was to evaluate the therapeutic efficacy of pirfenidone in mouse models of CP. We used caerulein and L-arginine models of CP and administered pirfenidone with ongoing injury, or in well-established disease. We evaluated for fibrosis by Sirius-red staining for collagen, immunohistochemistry, western blotting, and qPCR for fibrosis markers to show the salutary effects of pirfenidone in CP. Our results suggest that treatment with pirfenidone ameliorated CP related changes in the pancreas (i.e., atrophy, acinar cell loss, fibrosis, and inflammation) not only when administered with ongoing injury, but also in well-established models of caerulein as well as L-arginine induced CP. It reduces the pro-fibrotic phenotype of macrophages (in-vivo and in-vitro), reduces macrophage infiltration into the pancreas and alters the intra-pancreatic cytokine milieu preceding changes in histology. The therapeutic effect of pirfenidone is abrogated in absence of macrophages. Furthermore, it reduces collagen secretion, cytokine levels and fibrosis markers in pancreatic stellate cells in-vitro. As it is FDA approved, our findings in mouse models simulating clinical presentation of patients to the clinic, can be used as the basis of a clinical trial evaluating the efficacy of this drug as a therapeutic agent for CP.

Functional IKK/NF-κB signaling in pancreatic stellate cells is essential to prevent autoimmune pancreatitis

Pancreatic stellate cells (PSCs) are resident cells in the exocrine pancreas which contribute to pancreatic fibrogenesis and inflammation. Studies on NF-κB in pancreatitis so far focused mainly on the parenchymal and myeloid compartments. Here we show a protective immunomodulatory function of NF-κB in PSCs. Conditional deletion of NEMO (IKKγ) in PSCs leads to spontaneous pancreatitis with elevated circulating IgM, IgG and antinuclear autoantibodies (ANA) within 18 weeks. When further challenged with caerulein, NEMO^ΔCol1a2 mice show an exacerbated autoimmune phenotype characterized by increased infiltration of eosinophils, B and T lymphocytes with reduced latency period. Transcriptomic profiling shows that NEMO^ΔCol1a2 mice display molecular signatures resembling autoimmune pancreatitis patients. Mechanistically, we show that PSC^ΔNEMO cells produce high levels of CCL24 ex vivo which contributes to eosinophil recruitment, as neutralization with a CCL24 antibody abolishes the transwell migration of eosinophils. Our findings uncover an unexpected immunomodulatory role specifically of NF-κB in PSCs during pancreatitis.

A model of autoimmune pancreatitis is developed by blocking the activation of NF-κB in pancreatic stellate cells, via conditional deletion of NEMO (IKKγ), which presents strong pancreatic inflammation with eosinophilia after the induction of chronic pancreatitis by repeated caerulein challenges.

Murine Chronic Pancreatitis Model Induced by Partial Ligation of the Pancreatic Duct Encapsulates the Profile of Macrophage in Human Chronic Pancreatitis

Immune responses are an integral part of the pathogenesis of pancreatitis. Studies applying the mouse model of pancreatitis induced by partial ligation of the pancreatic duct to explore the pancreatic immune microenvironment are still lacking. The aim of the present study is to explore the macrophage profile and associated regulatory mechanisms in mouse pancreatitis, as well as the correlation with human chronic pancreatitis (CP). In the present study, the mouse model of pancreatitis was induced by partial ligation of the pancreatic duct. Mice in the acute phase were sacrificed at 0, 4, 8, 16, 32, 72 h after ligation, while mice in the chronic phase were sacrificed at 7, 14, 21, 28 days after ligation. We found that the pancreatic pathological score, expression of TNF-α and IL-6 were elevated over time and peaked at 72h in the acute phase, while in the chronic phase, the degree of pancreatic fibrosis peaked at day 21 after ligation. Pancreatic M1 macrophages and pyroptotic macrophages showed a decreasing trend over time, whereas M2 macrophages gradually rose and peaked at day 21. IL-4 is involved in the development of CP and is mainly derived from pancreatic stellate cells (PSCs). The murine pancreatitis model constructed by partial ligation of the pancreatic duct, especially the CP model, can ideally simulate human CP caused by obstructive etiologies in terms of morphological alterations and immune microenvironment characteristics.

Resveratrol inhibits the progression of premature senescence partially by regulating v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA) and sirtuin 1 (SIRT1)

Objective

To explore the effect of resveratrol in premature senescence and reveal its anti-premature senescence mechanisms through network pharmacology.

Methods

In this study, the H₂O₂-induced bone marrow mesenchymal stem cells (BMMSCs) premature senescence model is applied. Cell counting kit-8 assay, β-galactosidase staining and flow cytometry are conducted to detect the proliferation, senescence and apoptosis of BMMSCs. Bioinformatics analyses are used to screen and validate molecular targets of resveratrol acting on premature senescence. Dual-luciferase reporter assay is conducted to verify the interaction between v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA) and sirtuin 1 (SIRT1). RT-qPCR and western blot are adopted to detect mRNA and protein levels of RELA, SIRT1, senescence-related genes and apoptosis-related genes.

Results

First, we proved that resveratrol alleviated the H₂O₂-induced senescence of BMMSCs. Then, bioinformatics analysis revealed that RELA was the downstream target of resveratrol and SIRT1 was the downstream target of RELA, respectively, involved in premature aging. RELA/SIRT1 may be the potential target of resveratrol for premature senescence. Notably, rescue experiments indicated that resveratrol inhibited premature senescence partially through targeting regulation RELA/SIRT1.

Conclusion

In our study, we confirm the functional role of the resveratrol-RELA- SIRT1 axis in the progression of premature senescence, which provides a latent target for premature senescence treatment.

NF-κB and Pancreatic Cancer; Chapter and Verse

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the world's most lethal cancers. An increase in occurrence, coupled with, presently limited treatment options, necessitates the pursuit of new therapeutic approaches. Many human cancers, including PDAC are initiated by unresolved inflammation. The transcription factor NF-κB coordinates many signals that drive cellular activation and proliferation during immunity but also those involved in inflammation and autophagy which may instigate tumorigenesis. It is not surprising therefore, that activation of canonical and non-canonical NF-κB pathways is increasingly recognized as an important driver of pancreatic injury, progression to tumorigenesis and drug resistance. Paradoxically, NF-κB dysregulation has also been shown to inhibit pancreatic inflammation and pancreatic cancer, depending on the context. A pro-oncogenic or pro-suppressive role for individual components of the NF-κB pathway appears to be cell type, microenvironment and even stage dependent. This review provides an outline of NF-κB signaling, focusing on the role of the various NF-κB family members in the evolving inflammatory PDAC microenvironment. Finally, we discuss pharmacological control of NF-κB to curb inflammation, focussing on novel anti-cancer agents which reinstate the process of cancer cell death, the Smac mimetics and their pre-clinical and early clinical trials.

The effects of nuclear factor-kappa B in pancreatic stellate cells on inflammation and fibrosis of chronic pancreatitis

The activation of pancreatic stellate cells (PSCs) plays a critical role in the progression of pancreatic fibrosis. Nuclear factor‐kappa B (NF‐κB) is associated with chronic pancreatitis (CP). Previous evidence indicated that NF‐κB in acinar cells played a double‐edged role upon pancreatic injury, whereas NF‐κB in inflammatory cells promoted the progression of CP. However, the effects of NF‐κB in PSCs have not been studied. In the present study, using two CP models and RNAi strategy of p65 in cultured PSCs, we found that the macrophage infiltration and MCP‐1 expression were increased, and the NF‐κBp65 protein level was elevated. NF‐κBp65 was co‐expressed with PSCs. In vitro, TGF‐β1 induced overexpression of the TGF‐β receptor 1, phosphorylated TGF‐β1–activated kinase 1 (p‐TAK1) and NF‐κB in the PSCs. Moreover, the concentration of MCP‐1 in the supernatant of activated PSCs was elevated. The migration of BMDMs was promoted by the supernatant of activated PSCs. Further knockdown of NF‐κBp65 in PSCs resulted in a decline of BMDM migration, accompanied by a lower production of MCP‐1. These findings indicate that TGF‐β1 can induce the activation of NF‐κB pathway in PSCs by regulating p‐TAK1, and the NF‐κB pathway in PSCs may be a target of chronic inflammation and fibrosis.

Macrophages in pancreatitis: Mechanisms and therapeutic potential

Macrophages play a crucial role in the pathogenesis of pancreatitis that is a common gastrointestinal disease. Particularly, macrophages differentiate into different phenotypes and exert diverse functions in acute pancreatitis (AP) and chronic pancreatitis (CP), respectively. In AP, macrophages in the pancreas and other related organs are mainly activated and differentiated into a pro-inflammatory M1 phenotype, and furthermore secrete inflammatory cytokines and mediators, causing local inflammation of the pancreas, and even intractable systemic inflammatory response or multiple organ failure. In CP, macrophages often exhibit a M2 polarisation and interact with pancreatic stellate cells (PSCs) in an autocrine and paracrine cytokine-dependent manner to promote the progression of pancreatic fibrosis. As the severity of pancreatic fibrosis aggravates, the proportion of M2/M1 macrophage cytokines in the pancreas increases. The discovery of macrophages in the pathogenesis of pancreatitis has promoted the research of targeted drugs, which provides great potential for the effective treatment of pancreatitis. This paper provides an overview of the roles of various macrophages in the pathogenesis of pancreatitis and the current research status of pancreatitis immunotherapy targeting macrophages. The findings addressed in this review are of considerable significance for understanding the pivotal role of macrophages in pancreatitis.

MicroRNA-21-3p Engineered Umbilical Cord Stem Cell-Derived Exosomes Inhibit Tendon Adhesion

Purpose

As a common complication of tendon injury, tendon adhesion is an unresolved problem in clinical work. The aim of this study was to investigate whether human umbilical cord mesenchymal stem cell-derived exosomes (HUMSC-Exos), one of the most promising new-generation cell-free therapeutic agents, can improve tendon adhesion and explore potential-related mechanisms.

Methods

The rat Achilles tendon injury adhesion model was constructed in vivo, and the localization of HUMSC-Exos was used to evaluate the tendon adhesion. Rat fibroblast cell lines were treated with transforming growth factor β1 (TGF-β1) and/or HUMSC-Exos in vitro, and cell proliferation, apoptosis and gene expression were measured. MicroRNA (miRNA) sequencing and quantitative PCR (qPCR) analysis confirmed differential miRNAs. A specific miRNA antagonist (antagomir-21a-5p) was used to transform HUMSC-Exos and obtain modified exosomes to verify its efficacy and related mechanism of action.

Results

In this study, we found HUMSC-Exos reduced rat fibroblast proliferation and inhibited the expression of fibrosis genes: collagen III (COL III) and α-smooth muscle actin (α-SMA) in vitro. In the rat tendon adhesion model, topical application of HUMSC-Exos contributed to relief of tendon adhesion. Specifically, the fibrosis and inflammation-related genes were simultaneously inhibited by HUMSC-Exos. Further, miRNA sequencing of HUMSCs and HUMSC-Exos showed that miR-21a-3p was expressed at low abundance in HUMSC-Exos. The antagonist targeting miR-21a-3p was recruited for treatment of HUMSCs, and harvested HUMSC-Exos, which expressed low levels of miR-21a-3p, and expanded the inhibition of tendon adhesion in subsequent in vitro experiments.

Conclusion

Our results indicate that HUMSC-Exos may manipulate p65 activity by delivering low-abundance miR-21a-3p, ultimately inhibiting tendon adhesion. The findings may be promising for dealing with tendon adhesion.

Docosahexaenoic Acid Inhibits Expression of Fibrotic Mediators in Mice With Chronic Pancreatitis

Background

Chronic pancreatitis (CP) is an irreversible progressive disease that destroys exocrine parenchyma, which are replaced by fibrous tissue. As pancreatic fibrosis is a key feature of CP, reducing fibrotic protein content in the pancreas is crucial for preventing CP. Studies suggest that NF-κB facilitates the expression of fibrotic mediators in pancreas and protein kinase C-δ (PKC-δ) regulates NF-κB activation in stimulated pancreatic acinar cells. Docosahexaenoic acid (DHA) is an omega-3 fatty acid having anti-inflammatory and anti-fibrotic effects. It has been shown to inhibit NF-κB activity in cerulein-stimulated pancreatic acinar cells which is a cellular model of CP. In the present study, we investigated if DHA inhibits expression of fibrotic mediators by reducing PKC-δ and NF-κB expression in mouse pancreatic tissues with CP.

Methods

For six weeks, mice were weekly induced for acute pancreatitis to develop CP. Furthermore, acute pancreatitis was induced by hourly intraperitoneal injections of cerulein (50 μg/kg × 7). Mice were administered DHA (10 μM) via drinking water before and after CP induction.

Results

Cerulein-induced pancreatic damages like decreased pancreatic weight/total body weight, leukocyte infiltration, necrosis of acinar cells, and vacuolization were found to be inhibited by DHA. Additionally, DHA inhibited cerulein-induced fibrotic mediators like alpha-smooth muscle actin and fibronectin in pancreas. DHA reduced expression of PKC-δ and NF-κB p65 in pancreatic tissues of cerulein-treated mice.

Conclusions

DHA may be beneficial in preventing CP by suppressing pancreatic expression of fibrotic mediators.

Baicalin Ameliorates Pancreatic Fibrosis by Inhibiting the Activation of Pancreatic Stellate Cells in Mice with Chronic Pancreatitis

Pancreatic inflammation and fibrosis are typical pathological features in chronic pancreatitis (CP). Activated pancreatic stellate cells (PSCs) have been regarded as the core event in the development of pancreatic fibrosis and are considered to be the key target for treatment of CP. Baicalin (C₂₁H₁₈O₁₁), the main chemical composition of Baikal skullcap in the traditional Chinese medicines Dachaihu decoction (DCHD) and Xiaochaihu decoction (XCHD), has shown significant effects in the treatment of pancreatic fibrosis in CP mice; however, whether baicalin can inhibit the activation of PSCs and its underlying mechanism remain unclear. In this study, the influence of baicalin on activated PSCs in vitro and in vivo was investigated, and the results showed that Baicalin could significantly ameliorate the degree of pancreatic inflammation and fibrosis, while decreasing the levels of alpha-smooth muscle actin (α-SMA), F4/80 (surface markers of mouse macrophages), nuclear factor kappa-B (NF-κB), monocyte chemotactic protein 1 (MCP-1), and collagen type I alpha 1 (COL1A1)in the pancreas. Moreover, NF-κB and α-SMA were co-expressed in the pancreas of CP mice. Baicalin treatment markedly reduced the expression of co-location of α-SMA and NF-κB. In vitro, the protein expression levels of transforming growth factor-β receptor 1 (TGF-βR1), phosphorylated TGF-β activated kinase 1 p-TAK 1, and NF-κBp65 in PSCs were all remarkably reduced after treatment with baicalin. In addition, baicalin could inhibit MCP-1 mRNA expression in supernatant of activated PSCs, as well as the excessive migration of macrophages. Taken together, our findings indicated that baicalin could inhibit the TGF-β1/TGF-βR1/TAK1/NF-κB signaling pathway of activated PSCs, reduce the secretion of MCP-1, and further decrease the infiltration of macrophages and inflammation cells of the local microenvironment of the pancreas. Thus, this study provides a reliable experimental basis for baicalin in the prevention and treatment of CP.

Hic-5 deficiency protects cerulein-induced chronic pancreatitis via down-regulation of the NF-κB (p65)/IL-6 signalling pathway

Chronic pancreatitis (CP), characterized by pancreatic fibrosis, is a recurrent, progressive and irreversible disease. Activation of the pancreatic stellate cells (PSCs) is considered a core event in pancreatic fibrosis. In this study, we investigated the role of hydrogen peroxide-inducible clone-5 (Hic-5) in CP. Analysis of the human pancreatic tissue samples revealed that Hic-5 was overexpressed in patients with CP and was extremely low in healthy pancreas. Hic-5 was significant up-regulated in the activated primary PSCs independently from transforming growth factor beta stimulation. CP induced by cerulein injection was ameliorated in Hic-5 knockout (KO) mice, as shown by staining of tissue level. Simultaneously, the activation ability of the primary PSCs from Hic-5 KO mice was significantly attenuated. We also found that the Hic-5 up-regulation by cerulein activated the NF-κB (p65)/IL-6 signalling pathway and regulated the downstream extracellular matrix (ECM) genes such as α-SMA and Col1a1. Therefore, we determined whether suppressing NF-κB/p65 alleviated CP by treating mice with the NF-κB/p65 inhibitor triptolide in the cerulein-induced CP model and found that pancreatic fibrosis was alleviated by NF-κB/p65 inhibition. These findings provide evidence for Hic-5 as a therapeutic target that plays a crucial role in regulating PSCs activation and pancreatic fibrosis.

Induction of Pancreatic Inflammation Accelerates Pancreatic Tumorigenesis in Mice

Pancreatitis is a major risk factor for the development of pancreatic cancer. In genetically engineered mouse models, induction of pancreatic inflammation dramatically accelerates oncogenic KRas-induced fibrosis, precancerous PanIN formation, and tumorigenesis. Here we describe simple methods of secretagogue-induced experimental acute and chronic pancreatitis, the most commonly used pancreatitis models, and their applications in pancreatic cancer research. Additionally, the preparation of primary pancreatic acinar cells is introduced. Primary acinar cells can be used to study the early events of pancreatic inflammation and pancreatic acinar-to-ductal (ADM) metaplasia.

Genetically induced vs. classical animal models of chronic pancreatitis: a critical comparison

Chronic pancreatitis (CP) is an utmost complex disease that is pathogenetically linked to pancreas-intrinsic ( e.g., duct obstruction), environmental-toxic ( e.g., alcohol, smoking), and genetic factors. Studying such a complex disease naturally requires validated experimental models. In the past 2 decades, the various animal models of CP usually addressed either the pancreas-intrinsic ( e.g., the caerulein model), the environmental-toxic ( e.g., diet-induced models), or the genetic component of CP. As such, these models were far from mirroring CP in its full spectrum, and the correct choice of models was vital for valid scientific conclusions on CP. The quest for mechanistic, genetic models gave rise to models based on gene modification and transgene insertion, such as the PRSS1 and the IL-1β/IL-1β models. Recently, we witnessed the development of highly exciting models that rely on the importance of autophagy in CP, that is, the murine pancreas-specific Atg5 and LAMP2 knockout models. Today, critical comparison of these several models is more important than ever for guiding research on CP in an efficient direction. The present review outlines the characteristics of the new genetic models in comparison with the well-known classic models for CP, notes the caveats in the choice of models, and also indicates novel directions for model development.-Klauss, S., Schorn, S., Teller, S., Steenfadt, H., Friess, H., Ceyhan, G. O., Demir, I. K. Genetically induced vs. classical animal models of chronic pancreatitis: a critical comparison.

Therapeutic effect and potential mechanism of pioglitazone in rats with severe acute pancreatitis

Caspase recruitment domain-containing protein 9 (Card9) is located upstream of the nuclear factor kappa B (NF-κB) and p38 mitogen-activated protein kinase (MAPK) inflammatory pathways. This study investigated the therapeutic effect and potential mechanism of pioglitazone in rats with severe acute pancreatitis (SAP). SAP was induced by a retrograde infusion of 5.0% sodium taurocholate into the biliopancreatic duct of Sprague Dawley rats (n=54), which were then treated with pioglitazone. Blood and pancreatic tissues were harvested at 3, 6, and 12 h after SAP induction. Pancreatic pathological damage was evaluated by hematoxylin and eosin staining. Serum amylase, serum pro-inflammatory cytokines, and pancreatic myeloperoxidase (MPO) activities were determined by enzyme-linked immunosorbent assay. The expression of Card9 mRNA and protein in pancreatic tissues was detected by real-time polymerase chain reaction and western blotting. Pioglitazone had a therapeutic effect in treating rats with SAP by decreasing the level of amylase activity, ameliorating pancreatic histological damage, decreasing serum pro-inflammatory cytokine levels and tissue MPO activity, and downregulating the expression of NF-κB, p38MAPK, and Card9 mRNAs and proteins (P<0.05). The present study demonstrated that the inhibition of Card9 expression could reduce the severity of SAP. Card9 has a role in the pathogenic mechanism of SAP.

Autophagy, Inflammation, and Immune Dysfunction in the Pathogenesis of Pancreatitis

Pancreatitis is a common disorder with significant morbidity and mortality, yet little is known about its pathogenesis, and there is no specific or effective treatment. Its development involves dysregulated autophagy and unresolved inflammation, demonstrated by studies in genetic and experimental mouse models. Disease severity depends on whether the inflammatory response resolves or amplifies, leading to multi-organ failure. Dysregulated autophagy might promote the inflammatory response in the pancreas. We discuss the roles of autophagy and inflammation in pancreatitis, mechanisms of deregulation, and connections among disordered pathways. We identify gaps in our knowledge and delineate perspective directions for research. Elucidation of pathogenic mechanisms could lead to new targets for treating or reducing the severity of pancreatitis.

Altered hydroxymethylation is seen at regulatory regions in pancreatic cancer and regulates oncogenic pathways

Transcriptional deregulation of oncogenic pathways is a hallmark of cancer and can be due to epigenetic alterations. 5-Hydroxymethylcytosine (5-hmC) is an epigenetic modification that has not been studied in pancreatic cancer. Genome-wide analysis of 5-hmC-enriched loci with hmC-seal was conducted in a cohort of low-passage pancreatic cancer cell lines, primary patient-derived xenografts, and pancreatic controls and revealed strikingly altered patterns in neoplastic tissues. Differentially hydroxymethylated regions preferentially affected known regulatory regions of the genome, specifically overlapping with known H3K4me1 enhancers. Furthermore, base pair resolution analysis of cytosine methylation and hydroxymethylation with oxidative bisulfite sequencing was conducted and correlated with chromatin accessibility by ATAC-seq and gene expression by RNA-seq in pancreatic cancer and control samples. 5-hmC was specifically enriched at open regions of chromatin, and gain of 5-hmC was correlated with up-regulation of the cognate transcripts, including many oncogenic pathways implicated in pancreatic neoplasia, such as MYC, KRAS, VEGFA, and BRD4 Specifically, BRD4 was overexpressed and acquired 5-hmC at enhancer regions in the majority of neoplastic samples. Functionally, acquisition of 5-hmC at BRD4 promoter was associated with increase in transcript expression in reporter assays and primary samples. Furthermore, blockade of BRD4 inhibited pancreatic cancer growth in vivo. In summary, redistribution of 5-hmC and preferential enrichment at oncogenic enhancers is a novel regulatory mechanism in human pancreatic cancer.

Epithelial NEMO/IKKγ limits fibrosis and promotes regeneration during pancreatitis

OBJECTIVE

Inhibitory κB kinase (IKK)/nuclear factor κB (NF-κB) signalling has been implicated in the pathogenesis of pancreatitis, but its precise function has remained controversial. Here, we analyse the contribution of IKK/NF-κB signalling in epithelial cells to the pathogenesis of pancreatitis by targeting the IKK subunit NF-κB essential modulator (NEMO) (IKKγ), which is essential for canonical NF-κB activation.

DESIGN

Mice with a targeted deletion of NEMO in the pancreas were subjected to caerulein pancreatitis. Pancreata were examined at several time points and analysed for inflammation, fibrosis, cell death, cell proliferation, as well as cellular differentiation. Human samples were used to corroborate findings established in mice.

RESULTS

In acute pancreatitis, NEMO deletion in the pancreatic parenchyma resulted in minor changes during the early phase but led to the persistence of inflammatory and fibrotic foci in the recovery phase. In chronic pancreatitis, NEMO deletion aggravated inflammation and fibrosis, inhibited compensatory acinar cell proliferation, and enhanced acinar atrophy and acinar-ductal metaplasia. Gene expression analysis revealed sustained activation of profibrogenic genes and the CXCL12/CXCR4 axis in the absence of epithelial NEMO. In human chronic pancreatitis samples, the CXCL12/CXCR4 axis was activated as well, with CXCR4 expression correlating with the degree of fibrosis. The aggravating effects of NEMO deletion were attenuated by the administration of the CXCR4 antagonist AMD3100.

CONCLUSIONS

Our results suggest that NEMO in epithelial cells exerts a protective effect during pancreatitis by limiting inflammation and fibrosis and improving acinar cell regeneration. The CXCL12/CXCR4 axis is an important mediator of that effect and may also be of importance in human chronic pancreatitis.

Dachaihu decoction ameliorates pancreatic fibrosis by inhibiting macrophage infiltration in chronic pancreatitis

AIM

To explore the role of macrophages in chronic pancreatitis (CP) and the effect of Dachaihu decoction (DCHD) on pancreatic fibrosis in mice.

METHODS

KunMing mice were randomly divided into a control group, CP group, and DCHD group. In the CP and DCHD groups, mice were intraperitoneally injected with 20% L-arginine (3 g/kg twice 1 d/wk for 6 wk). Mice in the DCHD group were administered DCHD intragastrically at a dose of 14 g/kg/d 1 wk after CP induction. At 2 wk, 4 wk and 6 wk post-modeling, the morphology of the pancreas was observed using hematoxylin and eosin, and Masson staining. Interleukin-6 (IL-6) serum levels were assayed using an enzyme-linked immunosorbent assay. Double immunofluorescence staining was performed to observe the co-expression of F4/80 and IL-6 in the pancreas. Inflammatory factors including monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1α (MIP-1α) and IL-6 were determined using real time-polymerase chain reaction. Western blot analysis was used to detect fibronectin levels in the pancreas.

RESULTS

Compared with the control group, mice with 20% L-arginine-induced CP had obvious macrophage infiltration and a higher level of fibrosis. IL-6 serum concentrations were significantly increased. Double immunofluorescence staining showed that IL-6 and F4/80 were co-expressed in the pancreas. With the administration of DCHD, the infiltration of macrophages and degree of fibrosis in the pancreas were significantly attenuated; IL-6, MCP-1 and MIP-1α mRNA, and fibronectin levels were reduced.

CONCLUSION

The dominant role of macrophages in the development of CP was mainly related to IL-6 production. DCHD was effective in ameliorating pancreatic fibrosis by inhibiting macrophage infiltration and inflammatory factor secretion in the pancreas.

Immunology of pancreatitis and environmental factors

PURPOSE OF REVIEW

This report reviews recent aspects of pancreatitis immunology and environmental factors that link to development and progression of disease.

RECENT FINDINGS

Limited human and animal model studies have recently attempted to understand immune mechanisms that lead to the pathogenesis of acute and chronic pancreatitis. Based on these studies innate immune responses emerge as critical elements in disease pathogenesis and severity of inflammation. The immune basis for environmental factors such as smoking, which are highly associated with disease progression highlight novel cross talk mechanisms between immune and nonimmune pancreatic cells such as the pancreatic stellate cells.

SUMMARY

Better understanding of immune responses and signaling pathways are emerging as important contributors in pancreatitis development and progression. Such mechanisms are likely to offer future targetable therapies that can either halt or reverse disease progression.

RelA/p65 inhibition prevents tendon adhesion by modulating inflammation, cell proliferation, and apoptosis

Peritendinous tissue fibrosis which leads to poor tendon function is a worldwide clinical problem; however, its mechanism remains unclear. Transcription factor RelA/p65, an important subunit in the NF-κB complex, is known to have a critical role in many fibrotic diseases. Here, we show that RelA/p65 functions as a core fibrogenic regulator in tendon adhesion and that its inhibition exerts an anti-fibrogenic effect on peritendinous adhesion. We detected the upregulation of the NF-κB pathway in human tendon adhesion using a gene chip microarray assay and revealed the overexpression of p65 and extracellular matrix (ECM) proteins Collagen I, Collagen III, and α-smooth muscle actin (α-SMA) in human fibrotic tissues by immunohistochemistry and western blotting. We also found that in a rat model of tendon injury, p65 expression correlated with tendon adhesion, whereas its inhibition by small interfering (si)RNA prevented fibrous tissue formation and inflammatory reaction as evidenced by macroscopic, biomechanical, histological, immunohistochemical, and western blotting analyses. Furthermore, in cultured fibroblasts, p65-siRNA, p65-specific inhibitor, Helenalin and JSH23 suppressed cell proliferation and promoted apoptosis, whereas inhibiting the mRNA and protein expression of ECM components and cyclo-oxygenase-2, an inflammatory factor involved in tendon adhesion. Our findings indicate that p65 has a critical role in peritendinous tissue fibrosis and suggest that p65 knockdown may be a promising therapeutic approach to prevent tendon adhesion.

Animal models of gastrointestinal and liver diseases. Animal models of acute and chronic pancreatitis

Animal models of pancreatitis are useful for elucidating the pathogenesis of pancreatitis and developing and testing novel interventions. In this review, we aim to summarize the most commonly used animal models, overview their pathophysiology, and discuss their strengths and limitations. We will also briefly describe common animal study procedures and refer readers to more detailed protocols in the literature. Although animal models include pigs, dogs, opossums, and other animals, we will mainly focus on rodent models because of their popularity. Autoimmune pancreatitis and genetically engineered animal models will be reviewed elsewhere.

Differential role of Hedgehog signaling in human pancreatic (patho-) physiology: An up to date review

Since the discovery of the Hedgehog (Hh) pathway in drosophila melanogaster, our knowledge of the role of Hh in embryonic development, inflammation, and cancerogenesis in humans has dramatically increased over the last decades. This is the case especially concerning the pancreas, however, real therapeutic breakthroughs are missing until now. In general, Hh signaling is essential for pancreatic organogenesis, development, and tissue maturation. In the case of acute pancreatitis, Hh has a protective role, whereas in chronic pancreatitis, Hh interacts with pancreatic stellate cells, leading to destructive parenchym fibrosis and atrophy, as well as to irregular tissue remodeling with potency of initiating cancerogenesis. In vitro and in situ analysis of Hh in pancreatic cancer revealed that the Hh pathway participates in the development of pancreatic precursor lesions and ductal adenocarcinoma including critical interactions with the tumor microenvironment. The application of specific inhibitors of components of the Hh pathway is currently subject of ongoing clinical trials (phases 1 and 2). Furthermore, a combination of Hh pathway inhibitors and established chemotherapeutic drugs could also represent a promising therapeutic approach. In this review, we give a structured survey of the role of the Hh pathway in pancreatic development, pancreatitis, pancreatic carcinogenesis and pancreatic cancer as well as an overview of current clinical trials concerning Hh pathway inhibitors and pancreas cancer.

Effect of tiron on remote organ injury in rats with severe acute pancreatitis induced by L-arginine

Acute pancreatitis (AP) is an acute inflammatory disorder of the pancreas that can be complicated by involvement of other remote organs. Oxidative stress is known to have a crucial role in the development of pancreatic acinar damage and one of the main causes in multisystem organ failure in experimental AP. The aim of the study was to determine the effect of tiron on pancreas and remote organ damage in L-arginine (L-Arg) induced AP rat model. Thirty-two male rats were divided in random into four groups: control, tiron, L-Arg, and tiron with L-Arg. At the end of the experiment, blood samples were withdrawn for biochemical analysis. The pancreas, lung, kidney, and liver were collected for histopathological examination. Estimation of pancreatic water content was done. Analysis of pulmonary, hepatic, renal, and pancreatic lipid peroxide levels (MDA), superoxide dismutase (SOD), and reduced glutathione (GSH) were carried out. Finally, nuclear factor kappa B (NF-κB) and transforming growth factor β1 (TGF-β1) expression in pancreatic tissue was determined. Results indicated that treatment with tiron significantly decreased lipid peroxide levels and markedly increased both SOD activity and GSH level. Moreover, histopathological analysis further confirmed that administration of tiron relatively ameliorates pancreatic acinar cells and remote organ damage. Increased immunoreactivity of NF-κB and TGF-β1 were reduced also by tiron treatment. These findings pointed out the protective role of the mitochondrial antioxidant, tiron against AP induced by L-Arg.

Pathophysiology of chronic pancreatitis induced by dibutyltin dichloride joint ethanol in mice

AIM: To search for a new chronic pancreatitis model in mice suitable for investigating the pathophysiological processes leading to pancreatic fibrosis.

METHODS: The mice were randomly divided into 2 groups (n = 50), control group and model group. The mice in model group were given ethanol (10%) in drinking water after injection of dibutyltin dichloride (DBTC) (8 mg/kg BW) in tail vein. The mice in control group were injected with only solvent into tail vein (60% ethanol, 20% glycerine and 20% normal saline) and drank common water. At days 1, 7, 14, 28, and 56 after application of DBTC or solvent, 10 mice in one group were killed at each time point respectively. Blood was obtained by inferior vena cava puncture. The activity of amylase, concentration of bilirubin and hyaluronic acid in serum were assayed. The pancreas was taken to observe the pancreatic morphology by HE staining, and to characterize the pancreatic fibrosis by Masson staining. The expression of F4/80, CD3 and fibronectin (FN) were assayed by immuno-histochemistry or Immunofluorescence technique. Collagen type I (COL1A1) in pancreas were detected by Western blot. The expression of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinases-1 (TIMP-1) mRNA in the pancreas was assessed by real time PCR.

RESULTS: DBTC induced an acute edematous pancreatitis within 1 d. The dilated acini, scattered acinar cell necrosis, and inflammatory cells were found at day 7. Extensive infiltration with inflammatory cells following deposition of connective tissue was observed at day 14. At day 28, level of pancreatic fibrosis was aggravated. The pancreatic tissue was replaced by an extended interstitial fibrosis at the end of 2 mo. There was significant difference in the level of amylase, bilirubin and hyaluronic acid in serum between control group and model group (P < 0.05). The level of COL1A1 and FN in pancreas increased. The expression of MMP-1 mRNA in pancreas decreased, but TIMP-1 mRNA increased at model group.

CONCLUSION: DBTC joint Ethanol drinking can induce chronic pancreatitis in accordance with the pathophysiological modification of human. DBTC joint Ethanol-induced pancreatitis in mice is an effective and handy experimental method. The model is suitable to study the mechanism of pancreatic fibrosis in chronic pancreatitis.

Role of histone deacetylases in pancreas: Implications for pathogenesis and therapy

In the last years, our knowledge of the pathogenesis in acute and chronic pancreatitis (AP/CP) as well as in pancreatic cancerogenesis has significantly diversified. Nevertheless, the medicinal therapeutic options are still limited and therapeutic success and patient outcome are poor. Epigenetic deregulation of gene expression is known to contribute to development and progression of AP and CP as well as of pancreatic cancer. Therefore, the selective inhibition of aberrantly active epigenetic regulators can be an effective option for future therapies. Histone deacetylases (HDACs) are enzymes that remove an acetyl group from histone tails, thereby causing chromatin compaction and repression of transcription. In this review we present an overview of the currently available literature addressing the role of HDACs in the pancreas and in pancreatic diseases. In pancreatic cancerogenesis, HDACs play a role in the important process of epithelial-mesenchymal-transition, ubiquitin-proteasome pathway and, hypoxia-inducible-factor-1-angiogenesis. Finally, we focus on HDACs as potential therapeutic targets by summarizing currently available histone deacetylase inhibitors.

Association of claudin2 and PRSS1-PRSS2 polymorphisms with idiopathic recurrent acute and chronic pancreatitis: A case-control study from India

BACKGROUND

Gene polymorphisms, including those recently described in the claudin2 gene, have been implicated in recurrent acute (RAP) and chronic pancreatitis (CP). In India, RAP and CP have been associated with SPINK1 polymorphism. In this study, we evaluated the association of claudin2 and PRSS1-PRSS2 polymorphisms with idiopathic RAP and CP.

METHODS

We included 101 prospectively followed patients with documented idiopathic RAP (IRAP) and 96 patients who presented with idiopathic chronic pancreatitis (ICP) without previous history of AP. Controls were 156 unrelated individuals undergoing master health check or with non-specific symptoms. All the samples were genotyped for the SNPs rs7057398 in the claudin2 (CLDN2) gene and rs10273639 in the PRSS1 gene on Realtime polymerase chain reaction platform. Clinical data pertaining to patient and disease characteristics were recorded.

RESULTS

Claudin2 and PRSS1 polymorphisms were seen in a significantly higher proportion of female patients (P = 0.01 and 0.039, respectively). Thirty-three (32.7%) patients with IRAP developed features of early CP during follow-up (mean [95% confidence interval, CI] duration of 11.3 [8.9-13.7] months). Female patients with claudin2 (rs7057398) CC genotype were at significantly higher risk for IRAP (odds ratio [OR] [95% CI] 6.75 [1.82-23.67]; P = 0.004) and progression from IRAP to CP (OR [95% CI] 7.05 [1.51-33.01]; P = 0.007). CT genotype of PRSS1 (rs10273639) was associated IRAP (OR [95% CI] 2.59 [1.1-6.13]; P = 0.030), and both CT and CC genotypes with ICP in women (OR [95% CI] 2.86 [1.12-7.31]; P = 0.033 and 3.73 [1.03-13.59]; P = 0.048, respectively).

CONCLUSION

In this study, we have demonstrated the association of claudin2 (rs7057398) polymorphism with IRAP and progression of IRAP to CP, and PRSS1 (rs10273639) polymorphism with IRAP and ICP.

Induction of chronic pancreatitis by pancreatic duct ligation activates BMP2, apelin, and PTHrP expression in mice

Chronic pancreatitis (CP) is a devastating disease with no treatments. Experimental models have been developed to reproduce the parenchyma and inflammatory responses typical of human CP. For the present study, one objective was to assess and compare the effects of pancreatic duct ligation (PDL) to those of repetitive cerulein (Cer)-induced CP in mice on pancreatic production of bone morphogenetic protein-2 (BMP2), apelin, and parathyroid hormone-related protein (PTHrP). A second objective was to determine the extent of cross talk among pancreatic BMP2, apelin, and PTHrP signaling systems. We focused on BMP2, apelin, and PTHrP since these factors regulate the inflammation-fibrosis cascade during pancreatitis. Findings showed that PDL- and Cer-induced CP resulted in significant elevations in expression and peptide/protein levels of pancreatic BMP2, apelin, and PTHrP. In vivo mouse and in vitro pancreatic cell culture experiments demonstrated that BMP2 stimulated pancreatic apelin expression whereas apelin expression was inhibited by PTHrP exposure. Apelin or BMP2 exposure inhibited PTHrP expression, and PTHrP stimulated upregulation of gremlin, an endogenous inhibitor of BMP2 activity. Transforming growth factor-β (TGF-β) stimulated PTHrP expression. Together, findings demonstrated that PDL- and Cer-induced CP resulted in increased production of the pancreatic BMP2, apelin, and PTHrP signaling systems and that significant cross talk occurred among pancreatic BMP2, apelin, and PTHrP. These results together with previous findings imply that these factors interact via a pancreatic network to regulate the inflammation-fibrosis cascade during CP. More importantly, this network communicated with TGF-β, a key effector of pancreatic pathophysiology. This novel network may be amenable to pharmacologic manipulations during CP in humans.

Alternatively activated macrophages promote pancreatic fibrosis in chronic pancreatitis

Chronic pancreatitis (CP) is a progressive and irreversible inflammatory and fibrotic disease with no cure. Unlike acute pancreatitis (AP), we find that alternatively activated macrophages (AAMs) are dominant in mouse and human CP. AAMs are dependent on interleukin (IL)-4 and IL-13 signalling, and we show that mice lacking IL-4Rα, myeloid-specific IL-4Rα and IL-4/IL-13 were less susceptible to pancreatic fibrosis. Furthermore, we demonstrate that mouse and human pancreatic stellate cells (PSCs) are a source of IL-4/IL-13. Notably, we show that pharmacologic inhibition of IL-4/IL-13 in human ex vivo studies as well as in established mouse CP decreases pancreatic AAMs and fibrosis. We identify a critical role for macrophages in pancreatic fibrosis and in turn PSCs as important inducers of macrophage-alternative activation. Our study challenges and identifies pathways involved in crosstalk between macrophages and PSCs that can be targeted to reverse or halt pancreatic fibrosis progression.

Vitamin D receptor-mediated stromal reprogramming suppresses pancreatitis and enhances pancreatic cancer therapy

The poor clinical outcome in pancreatic ductal adenocarcinoma (PDA) is attributed to intrinsic chemoresistance and a growth-permissive tumor microenvironment. Conversion of quiescent to activated pancreatic stellate cells (PSCs) drives the severe stromal reaction that characterizes PDA. Here, we reveal that the vitamin D receptor (VDR) is expressed in stroma from human pancreatic tumors and that treatment with the VDR ligand calcipotriol markedly reduced markers of inflammation and fibrosis in pancreatitis and human tumor stroma. We show that VDR acts as a master transcriptional regulator of PSCs to reprise the quiescent state, resulting in induced stromal remodeling, increased intratumoral gemcitabine, reduced tumor volume, and a 57% increase in survival compared to chemotherapy alone. This work describes a molecular strategy through which transcriptional reprogramming of tumor stroma enables chemotherapeutic response and suggests vitamin D priming as an adjunct in PDA therapy. PAPERFLICK:

Effect of oxymatrine on lipopolysaccharide induced expression of NF-κB in pancreatic stellate cells

AIM: To investigate the effect of oxymatrine (OM) on lipopolysaccharide (LPS) induced expression of nuclear factor κB (NF-κB) in pancreatic stellate cells (LTC-14).

METHODS: LTC-14 cells were cultured with suitable concentrations of LPS as well as the corresponding concentrations of OM. Cell proliferation was detected by MTT assay. The expression of cytoplasmic and nuclear NF-κB was detected by immunohistochemistry. The expression of NF-κB mRNA was evaluated by Q-PCR. The protein expression of NF-κB was measured by Western blot.

RESULTS: OM inhibited the proliferation of LTC-14 cells in a time- and dose-dependent manner. The expression of NF-κB mRNA and protein was significantly increased in LTC-14 cells incubated with LPS (10 μg/mL), which could be down-regulated by OM. The nuclear translocation of NF-κB could also be inhibited by OM.

CONCLUSION: The reduction of NF-κB mRNA and protein as well as the inhibition of NF-κB nuclear translocation might be involved in the therapeutic effects of OM on pancreatic fibrosis.

Astragaloside IV ameliorates acute pancreatitis in rats by inhibiting the activation of nuclear factor-κB

This study aimed to investigate the effects of astragaloside IV (AS-IV; 3-O-β-D-xylopyranosyl-6-O-β-D-glucopyranosylcycloastragenol), which has been reported to have comprehensive pharmacological functions, on sodium taurocholate (NaTc)/L-arginine (L-Arg)-induced acute pancreatitis (AP) in rats in vivo and in rat pancreatic acinar cells in vitro. NaTc-induced experimental AP was induced in rats by injecting 4% NaTc (0.1 ml/100 g) in the retrograde direction of the biliopancreatic duct. L-Arg-induced experimental AP was induced in rats by 2 intraperitoneal injections of 20% L-arg (3 g/kg), with an interval of 1 h between the injections. The rats were pre-treated AS-IV (50 mg/kg) or the vehicle (DMSO) 2 h prior to the induction of AP. Enzyme-linked immunosorbent assay, H&E staining, myeloperoxidase (MPO) activity, reverse transcription-quantitative PCR, western blot analysis and immunohistochemistry were used to evaluate the effects of AS-IV on AP. The results revealed that treatment with AS-IV significantly reduced serum amylase and lipase levels, pancreatic pathological alterations, the secretion of pro-inflammatory cytokines, MPO activity, and the protein expression of nuclear factor-κB (NF-κB) in vivo. Moreover, pre-treatment with AS-IV significantly increased the expression levels of manganese superoxide dismutase and cuprum/zinc superoxide dismutase. In the in vitro experiment, treatment of the cells with AS-IV aslo reduced rat pancreatic acinar cell necrosis and nuclear NF-κB activity, and enhanced the protein expression of superoxide dismutase. In conclusion, this study indicates that the protective effects of AS-IV on experimental AP in rats may be closely related to the inhibition of NF-κB. In addition, our results indicate that AS-IV may exert potential antioxidant effects on AP. Therefore, AS-IV may be an effective therapeutic agent for AP.

Immune cells and immune-based therapy in pancreatitis

Alcohol and gallstones are the most common etiologic factors in acute pancreatitis (AP). Recurrent AP can lead to chronic pancreatitis (CP). Although the underlying pathophysiology of the disease is complex, immune cells are critical in the pathogenesis of pancreatitis and determining disease severity. In this review, we discuss the role of innate and adaptive immune cells in both AP and CP, potential immune-based therapeutic targets, and animal models used to understand our knowledge of the disease. The relative difficulty of obtaining human pancreatic tissue during pancreatitis makes animal models necessary. Animal models of pancreatitis have been generated to understand disease pathogenesis, test therapeutic interventions, and investigate immune responses. Although current animal models do not recapitulate all aspects of human disease, until better models can be developed available models are useful in addressing key research questions. Differences between experimental and clinical pancreatitis need consideration, and when therapies are tested, models with established disease ought to be included.

Recombinant interleukin-1 receptor antagonist attenuates the severity of chronic pancreatitis induced by TNBS in rats

Chronic pancreatitis (CP) is a common disease in the department of gastroenterology, with the main symptoms of exocrine and/or endocrine insufficiency and abdominal pain. The pathogenic mechanism of CP is still not fully clarified and the aims of treatment now are to relieve symptoms. In this study, we attempted to find a connection between interleukin-1β (IL-1β) and interleukin-1 receptor antagonist (IL-1Ra) in trinitrobenzene sulfonic acid (TNBS)-induced chronic pancreatitis, and then the therapeutic effect of recombinant IL-1Ra was also detected in the CP model. Chronic pancreatitis was induced by intraductal infusion of TNBS in SD rats followed by a consecutive administration of rIL-1Ra, and the histological changes and collagen content in the pancreas were measured, as well as the abdominal hypersensitivity. We found that rhIL-1Ra could attenuate the severity of chronic pancreatic injury, modulate the extracellular matrix secretion, focal proliferation and apoptosis, and cellular immunity in TNBS-induced CP. Interestingly, rIL-1Ra could also block the pancreatitis-induced referred abdominal hypersensitivity. In conclusion, IL-1Ra may play a protective role in CP and rIL-1Ra would be a potential therapeutic target for the treatment of CP, while its possible mechanisms and clinical usage still need further investigation.

Regeneration and repair of the exocrine pancreas

Pancreatitis is caused by inflammatory injury to the exocrine pancreas, from which both humans and animal models appear to recover via regeneration of digestive enzyme-producing acinar cells. This regenerative process involves transient phases of inflammation, metaplasia, and redifferentiation, driven by cell-cell interactions between acinar cells, leukocytes, and resident fibroblasts. The NFκB signaling pathway is a critical determinant of pancreatic inflammation and metaplasia, whereas a number of developmental signals and transcription factors are devoted to promoting acinar redifferentiation after injury. Imbalances between these proinflammatory and prodifferentiation pathways contribute to chronic pancreatitis, characterized by persistent inflammation, fibrosis, and acinar dedifferentiation. Loss of acinar cell differentiation also drives pancreatic cancer initiation, providing a mechanistic link between pancreatitis and cancer risk. Unraveling the molecular bases of exocrine regeneration may identify new therapeutic targets for treatment and prevention of both of these deadly diseases.

Acinar cell-specific knockout of the PTHrP gene decreases the proinflammatory and profibrotic responses in pancreatitis

Pancreatitis is a necroinflammatory disease with acute and chronic manifestations. Accumulated damage incurred during repeated bouts of acute pancreatitis (AP) can lead to chronic pancreatitis (CP). Pancreatic parathyroid hormone-related protein (PTHrP) levels are elevated in a mouse model of cerulein-induced AP. Here, we show elevated PTHrP levels in mouse models of pancreatitis induced by chronic cerulein administration and pancreatic duct ligation. Because acinar cells play a major role in the pathophysiology of pancreatitis, mice with acinar cell-specific targeted disruption of the Pthrp gene (PTHrP(Δacinar)) were generated to assess the role of acinar cell-secreted PTHrP in pancreatitis. These mice were generated using Cre-LoxP technology and the acinar cell-specific elastase promoter. PTHrP(Δacinar) exerted protective effects in cerulein and pancreatic duct ligation models, evident as decreased edema, histological damage, amylase secretion, pancreatic stellate cell (PSC) activation, and extracellular matrix deposition. Treating acinar cells in vitro with cerulein increased IL-6 expression and NF-κB activity; these effects were attenuated in PTHrP(Δacinar) cells, as were the cerulein- and carbachol-induced elevations in amylase secretion. The cerulein-induced upregulation of procollagen I expression was lost in PSCs from PTHrP(Δacinar) mice. PTHrP immunostaining was elevated in human CP sections. The cerulein-induced upregulation of IL-6 and ICAM-1 (human acinar cells) and procollagen I (human PSCs) was suppressed by pretreatment with the PTH1R antagonist, PTHrP (7-34). These findings establish PTHrP as a novel mediator of inflammation and fibrosis associated with CP. Acinar cell-secreted PTHrP modulates acinar cell function via its effects on proinflammatory cytokine release and functions via a paracrine pathway to activate PSCs.

Matrix metalloproteinase-10 expression is induced during hepatic injury and plays a fundamental role in liver tissue repair

BACKGROUND & AIMS

Upon tissue injury, the liver mounts a potent reparative and regenerative response. A role for proteases, including serine and matrix metalloproteinases (MMPs), in this process is increasingly recognized. We have evaluated the expression and function of MMP10 (stromelysin-2) in liver wound healing and regeneration.

METHODS

The hepatic expression of MMP10 was examined in two murine models: liver regeneration after two-thirds partial hepatectomy (PH) and bile duct ligation (BDL). MMP10 was detected in liver tissues by qPCR, western blotting and immunohistochemistry. The effect of growth factors and toll-like receptor 4 (TLR4) agonists on MMP10 expression was studied in cultured parenchymal and biliary epithelial cells and macrophages respectively. The role of MMP10 was evaluated by comparing the response of Mmp10+/+ and Mmp10-/- mice to PH and BDL. The intrahepatic turnover of the extracellular matrix proteins fibrin (ogen) and fibronectin was examined.

RESULTS

MMP10 mRNA was readily induced after PH and BDL. MMP10 protein was detected in hepatocytes, cholangiocytes and macrophages. In cultured liver epithelial cells, MMP10 expression was additively induced by transforming growth factor-β and epidermal growth factor receptor ligands. TLR4 ligands also stimulated MMP10 expression in macrophages. Lack of MMP10 resulted in increased liver injury upon PH and BDL. Resolution of necrotic areas was impaired, and Mmp10-/- mice showed increased fibrogenesis and defective turnover of fibrin (ogen) and fibronectin.

CONCLUSIONS

MMP10 expression is induced during mouse liver injury and participates in the hepatic wound healing response. The profibrinolytic activity of MMP10 may be essential in this novel hepatoprotective role.

Risk factors for pancreatic cancer: underlying mechanisms and potential targets

PURPOSE OF THE REVIEW

Pancreatic cancer is extremely aggressive, forming highly chemo-resistant tumors, and has one of the worst prognoses. The evolution of this cancer is multi-factorial. Repeated acute pancreatic injury and inflammation are important contributing factors in the development of pancreatic cancer. This article attempts to understand the common pathways linking pancreatitis to pancreatic cancer.

RECENT FINDINGS

Intracellular activation of both pancreatic enzymes and the transcription factor NF-κB are important mechanisms that induce acute pancreatitis (AP). Recurrent pancreatic injury due to genetic susceptibility, environmental factors such as smoking, alcohol intake, and conditions such as obesity lead to increases in oxidative stress, impaired autophagy and constitutive activation of inflammatory pathways. These processes can stimulate pancreatic stellate cells, thereby increasing fibrosis and encouraging chronic disease development. Activation of oncogenic Kras mutations through inflammation, coupled with altered levels of tumor suppressor proteins (p53 and p16) can ultimately lead to development of pancreatic cancer.

SUMMARY

Although our understanding of pancreatitis and pancreatic cancer has tremendously increased over many years, much remains to be elucidated in terms of common pathways linking these conditions.

Necro-inflammatory response of pancreatic acinar cells in the pathogenesis of acute alcoholic pancreatitis

The role of pancreatic acinar cells in initiating necro-inflammatory responses during the early onset of alcoholic acute pancreatitis (AP) has not been fully evaluated. We investigated the ability of acinar cells to generate pro- and anti-inflammatory mediators, including inflammasome-associated IL-18/caspase-1, and evaluated acinar cell necrosis in an animal model of AP and human samples. Rats were fed either an ethanol-containing or control diet for 14 weeks and killed 3 or 24 h after a single lipopolysaccharide (LPS) injection. Inflammasome components and necro-inflammation were evaluated in acinar cells by immunofluorescence (IF), histology, and biochemical approaches. Alcohol exposure enhanced acinar cell-specific production of TNFα, IL-6, MCP-1 and IL-10, as early as 3 h after LPS, whereas IL-18 and caspase-1 were evident 24 h later. Alcohol enhanced LPS-induced TNFα expression, whereas blockade of LPS signaling diminished TNFα production in vitro, indicating that the response of pancreatic acinar cells to LPS is similar to that of immune cells. Similar results were observed from acinar cells in samples from patients with acute/recurrent pancreatitis. Although morphologic examination of sub-clinical AP showed no visible signs of necrosis, early loss of pancreatic HMGB1 and increased systemic levels of HMGB1 and LDH were observed, indicating that this strong systemic inflammatory response is associated with little pancreatic necrosis. These results suggest that TLR-4-positive acinar cells respond to LPS by activating the inflammasome and producing pro- and anti-inflammatory mediators during the development of mild, sub-clinical AP, and that these effects are exacerbated by alcohol injury.

Pancreatitis activates pancreatic apelin-APJ axis in mice

Pancreatitis is classified into acute pancreatitis (AP) and chronic pancreatitis (CP). Apelin, a small regulatory peptide, is the endogenous ligand for the APJ receptor. Apelin and APJ are expressed in the pancreas. The aims of this study were to examine whether apelin influences the inflammatory and fibrosis responses to pancreatitis in mice and to identify mechanisms behind apelin's activities. Supramaximal cerulein induction of AP or CP caused significant (P < 0.05) elevations in pancreatic apelin and APJ expression. Levels declined during the recovery phases. In apelin gene-knockout mice with pancreatitis, pancreatic neutrophil invasion and myeloperoxidase activity were enhanced significantly, and apelin treatment suppressed both. Apelin exposure reduced CP-induced elevations of extracellular matrix-associated proteins. Apelin inhibited PDGF-simulated connective tissue growth factor production and proliferation of pancreatic stellate cells (PSCs). Serum granulocyte colony-stimulating factor and keratinocyte cytokine levels were higher in apelin gene-knockout than wild-type mice with pancreatitis. Apelin reduced AP- and CP-induced elevations in pancreatic NF-κB activation. Together, these findings imply that the pancreatic apelin-APJ system functions to curb the inflammatory and fibrosis responses during pancreatitis. Furthermore, findings suggest that apelin reduces inflammation and fibrosis by reducing neutrophil recruitment and PSC activity. Inhibition of neutrophil invasion may be mediated by reduced keratinocyte cytokine and granulocyte colony-stimulating factor secretion. Apelin-induced reductions in PSC proliferation and connective tissue growth factor production are putative mechanisms underlying apelin's inhibition of extracellular matrix production. The apelin-associated changes in NF-κB binding may be linked to apelin's regulation of pancreatic inflammatory and fibrosis responses during pancreatitis.