Substance P treatment stimulates chemokine synthesis in pancreatic acinar cells via the activation of NF-kappaB

Molecular mechanisms of pain in acute pancreatitis: recent basic research advances and therapeutic implications

Although severe abdominal pain is the main symptom of acute pancreatitis, its mechanisms are poorly understood. An emerging body of literature evidence indicates that neurogenic inflammation might play a major role in modulating the perception of pain from the pancreas. Neurogenic inflammation is the result of a crosstalk between injured pancreatic tissue and activated neurons, which leads to an auto-amplification loop between inflammation and pain during the progression of acute pancreatitis. In this review, we summarize recent findings on the role of neuropeptides, ion channels, and the endocannabinoid system in acute pancreatitis-related pain. We also highlight potential therapeutic strategies that could be applied for managing severe pain in this disease.

Effectiveness of Chengqi-series decoctions in treating severe acute pancreatitis: A Systematic review and meta-analysis

BACKGROUND

Evidence suggests that Dachengqi and its modified decoctions are effective for treating abdominal pain, multiple organ dysfunction syndrome (MODS) and inflammation in various disease conditions. We performed a meta-analysis to ascertain the effectiveness of a series of chengqi decoctions in patients with severe acute pancreatitis (SAP).

METHODS

We searched Pubmed, Embase, Cochrane library, Web of Science, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature, Wanfang database and China Science and Technology Journal Database before August 2022 to identify eligible randomized controlled trials (RCTs). Mortality and MODS were chosen as primary outcomes. Secondary outcomes included time until relief of abdominal pain, APACHE II score, complications, effectiveness, IL-6 and TNF-α levels. The risk ratio (RR) and standardized mean difference (SMD) with a 95% confidence interval (CI) were selected as effect measures. The quality of evidence was independently assessed by two reviewers using Grading of Recommendations Assessment Development and Evaluation (GRADE) system.

RESULTS

Twenty-three RCTs (n = 1865) were finally included. The results showed that, compared with routine therapies, chengqi-series decoctions (CQSDs) treatment groups were associated with lower mortality rate (RR: 0.41, 95%CI: 0.32 to 0.53, p = 0.992) and incidence of MODS (RR: 0.48, 95%CI: 0.36 to 0.63, p = 0.885). They also reduced remission time of abdominal pain (SMD: -1.66, 95%CI: -1.98 to -1.35, p = 0.000), complications (RR: 0.52, 95%CI: 0.39 to 0.68, p = 0.716), APACHE II score (SMD: -1.04, 95%CI:-1.55 to -0.54, p = 0.003), IL-6 (SMD: -1.5, 95%CI: -2.16 to -0.85, p = 0.000), TNF-α (SMD: -1.18, 95%CI: -1.71 to -0.65, p = 0.000), and improved curative effectiveness (RR:1.22, 95%CI: 1.14 to 1.31, p = 0.757). The certainty of the evidence for these outcomes was low to moderate.

CONCLUSION

CQSDs seem to be effective therapy for SAP patients with notable reductions in mortality, MODS and abdominal pain, with low quality evidence. Large-scale, multi-center RCTs that are more meticulous are advised in order to produce superior evidence.

Critical thresholds: key to unlocking the door to the prevention and specific treatments for acute pancreatitis

Acute pancreatitis (AP), an acute inflammatory disorder of the exocrine pancreas, is one of the most common gastrointestinal diseases encountered in emergency departments with no specific treatments. Laboratory-based research has formed the cornerstone of endeavours to decipher the pathophysiology of AP, because of the limitations of such study in human beings. While this has provided us with substantial understanding, we cannot answer several pressing questions. These are: (a) Why is it that only a minority of individuals with gallstones, or who drink alcohol excessively, or are exposed to other causative factors develop AP? (b) Why do only some develop more severe manifestations of AP with necrosis and/or organ failure? (c) Why have we been unable to find an effective therapeutic for AP? This manuscript provides a state-of-the-art review of our current understanding of the pathophysiology of AP providing insights into the unanswered clinical questions. We describe multiple protective factors operating in most people, and multiple stressors that in a minority induce AP, independently or together, via amplification loops. We present testable hypotheses aimed at halting progression of severity for the development of effective treatments for this common unpredictable disease.

Hydrogen Sulfide and its Interaction with Other Players in Inflammation

Hydrogen sulfide (H₂S) plays a vital role in human physiology and in the pathophysiology of several diseases. In addition, a substantial role of H₂S in inflammation has emerged. This chapter will discuss the involvement of H₂S in various inflammatory diseases. Furthermore, the contribution of reactive oxygen species (ROS), adhesion molecules, and leukocyte recruitment in H₂S-mediated inflammation will be discussed. The interrelationship of H₂S with other gasotransmitters in inflammation will also be examined. There is mixed literature on the contribution of H₂S to inflammation due to studies reporting both pro- and anti-inflammatory actions. These apparent discrepancies in the literature could be resolved with further studies.

Protective effect of diallyl disulfide against cerulein-induced acute pancreatitis and associated lung injury in mice

Garlic (Allium sativum) - derived organosulfur compound diallyl disulfide (DADS) possesses antioxidant, anti-inflammatory and anti-cancer effects. This study was aimed to investigate the anti-inflammatory role and the underlying molecular mechanisms of DADS in cerulein-induced acute pancreatitis (AP) and associated lung injury. Administration of DADS significantly attenuated the severity of pancreatic and pulmonary inflammation by inhibiting cerulein induced serum amylase, myeloperoxidase activity (MPO) and histological changes in pancreas and lung. Furthermore, the anti-inflammatory effect of DADS was associated with the decrease in tumor necrosis factor (TNF)-α,cystathionine-γ-lyase (CSE), preprotachykinin A (PPTA), neurokinin-1-receptor (NK1R) expression and hydrogen sulfide (H₂S) production in both pancreas and lung. In addition, DADS reduced caerulein-induced I-κB degradation and subsequent translocation of NF-κB in the pancreas and lung. These results show for the first time that in AP, DADS exhibits an anti-inflammatory effect by inhibiting CSE/H₂S and SP/NK1R signaling and NF-кB pathway.

Myeloid-Derived Suppressor Cells in Sepsis

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells characterized by their immunosuppressive functions. MDSCs expand during chronic and acute inflammatory conditions, the best described being cancer. Recent studies uncovered an important role of MDSCs in the pathogenesis of infectious diseases along with sepsis. Here we discuss the mechanisms underlying the expansion and immunosuppressive functions of MDSCs, and the results of preclinical and clinical studies linking MDSCs to sepsis pathogenesis. Strikingly, all clinical studies to date suggest that high proportions of blood MDSCs are associated with clinical worsening, the incidence of nosocomial infections and/or mortality. Hence, MDSCs are attractive biomarkers and therapeutic targets for sepsis, especially because these cells are barely detectable in healthy subjects. Blocking MDSC-mediated immunosuppression and trafficking or depleting MDSCs might all improve sepsis outcome. While some key aspects of MDSCs biology need in depth investigations, exploring these avenues may participate to pave the way toward the implementation of personalized medicine and precision immunotherapy for patients suffering from sepsis.

The Role of Autophagy and Related MicroRNAs in Inflammatory Bowel Disease

Accumulating evidence demonstrates that microRNA- (miR-) mediated posttranscriptional regulation plays an important role in autophagy in inflammatory bowel disease (IBD), a disease that is difficult to manage clinically because of the associated chronic recurrent nonspecific inflammation. Research indicates that microRNAs regulate autophagy via different pathways, playing an important role in the IBD process and providing a new perspective for IBD research. Related studies have shown that miR-142-3p, miR-320, miR-192, and miR-122 target NOD2, an IBD-relevant autophagy gene, to modulate autophagy in IBD. miR-142-3p, miR-93, miR-106B, miR-30C, miR-130a, miR-346, and miR-20a regulate autophagy by targeting ATG16L1 through several different pathways. miR-196 can downregulate IRGM and suppress autophagy by inhibiting the accumulation of LC3II. During the endoplasmic reticulum stress response, miR-665, miR-375, and miR-150 modulate autophagy by regulating the unfolded protein response, which may play an important role in IBD intestinal fibrosis. Regarding autophagy-related pathways, miR-146b, miR-221-5p, miR-132, miR-223, miR-155, and miR-21 regulate NF-κB or mTOR signaling to induce or inhibit autophagy in intestinal cells by releasing anti- or proinflammatory factors, respectively.

The Role of Neurogenic Inflammation in Blood-Brain Barrier Disruption and Development of Cerebral Oedema Following Acute Central Nervous System (CNS) Injury

Acute central nervous system (CNS) injury, encompassing traumatic brain injury (TBI) and stroke, accounts for a significant burden of morbidity and mortality worldwide, largely attributable to the development of cerebral oedema and elevated intracranial pressure (ICP). Despite this, clinical treatments are limited and new therapies are urgently required to improve patient outcomes and survival. Originally characterised in peripheral tissues, such as the skin and lungs as a neurally-elicited inflammatory process that contributes to increased microvascular permeability and tissue swelling, neurogenic inflammation has now been described in acute injury to the brain where it may play a key role in the secondary injury cascades that evolve following both TBI and stroke. In particular, release of the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) appear to be critically involved. In particular, increased SP expression is observed in perivascular tissue following acute CNS injury, with the magnitude of SP release being related to both the frequency and degree of the insult. SP release is associated with profound blood-brain barrier disruption and the subsequent development of vasogenic oedema, as well as neuronal injury and poor functional outcomes. Inhibition of SP through use of a neurokinin 1 (NK1) antagonist is highly beneficial following both TBI and ischaemic stroke in pre-clinical models. The role of CGRP is more unclear, especially with respect to TBI, with both elevations and reductions in CGRP levels reported following trauma. However, a beneficial role has been delineated in stroke, given its potent vasodilatory effects. Thus, modulating neuropeptides represents a novel therapeutic target in the treatment of cerebral oedema following acute CNS injury.

Neurogenic inflammation after traumatic brain injury and its potentiation of classical inflammation

Background

The neuroinflammatory response following traumatic brain injury (TBI) is known to be a key secondary injury factor that can drive ongoing neuronal injury. Despite this, treatments that have targeted aspects of the inflammatory pathway have not shown significant efficacy in clinical trials.

Main body

We suggest that this may be because classical inflammation only represents part of the story, with activation of neurogenic inflammation potentially one of the key initiating inflammatory events following TBI. Indeed, evidence suggests that the transient receptor potential cation channels (TRP channels), TRPV1 and TRPA1, are polymodal receptors that are activated by a variety of stimuli associated with TBI, including mechanical shear stress, leading to the release of neuropeptides such as substance P (SP). SP augments many aspects of the classical inflammatory response via activation of microglia and astrocytes, degranulation of mast cells, and promoting leukocyte migration. Furthermore, SP may initiate the earliest changes seen in blood-brain barrier (BBB) permeability, namely the increased transcellular transport of plasma proteins via activation of caveolae. This is in line with reports that alterations in transcellular transport are seen first following TBI, prior to decreases in expression of tight-junction proteins such as claudin-5 and occludin. Indeed, the receptor for SP, the tachykinin NK1 receptor, is found in caveolae and its activation following TBI may allow influx of albumin and other plasma proteins which directly augment the inflammatory response by activating astrocytes and microglia.

Conclusions

As such, the neurogenic inflammatory response can exacerbate classical inflammation via a positive feedback loop, with classical inflammatory mediators such as bradykinin and prostaglandins then further stimulating TRP receptors. Accordingly, complete inhibition of neuroinflammation following TBI may require the inhibition of both classical and neurogenic inflammatory pathways.

Src as the link between inflammation and cancer

Although a causal link between chronic inflammation and cancer has been established, the exact molecular mechanism linking inflammation to cancer remains largely unknown. It was previously postulated that molecular switches responsible for cancer cell development, and for infiltration of inflammatory cells into cancer, were divided into a distinct set of intracellular proteins and signaling pathways. However, recent evidence suggests that both tumor cells and tumor-infiltrating immune cells utilize the same kinases, mostly that of Src family, to facilitate cancer development and progression. In the past few years several groups have found that Src activation both in cancer and inflammatory cells is mainly driven by pro-inflammatory cytokines within the tumor microenvironment. Here we evaluate the cross talks between Src kinase pathways in immune cells and cancer cells. We conclude that Src might serve as a critical mechanistic link between inflammation and cancer, mediating and propagating a cycle between immune and tissue cells that can ultimately lead to the development and progression of cancer.

The effect of CSE gene deletion in caerulein-induced acute pancreatitis in the mouse

Hydrogen sulfide (H2S) has been reported to be involved in the signaling of the inflammatory response; however, there are differing views as to whether it is pro- or anti-inflammatory. In this study, we sought to determine whether endogenously synthesized H2S via cystathionine-γ-lyase (CSE) plays a pro- or anti-inflammatory role in caerulein-induced pancreatitis. To investigate this, we used mice genetically deficient in CSE to elucidate the function of CSE in caerulein-induced acute pancreatitis. We compared the inflammatory response and tissue damage of wild-type (WT) and CSE knockout (KO) mice following 10 hourly administrations of 50 μg/kg caerulein or saline control. From this, we found that the CSE KO mice showed significantly less local pancreatic damage as well as acute pancreatitis-associated lung injury compared with the WT mice. There were also lower levels of pancreatic eicosanoid and cytokines, as well as reduced acinar cell NF-κB activation in the CSE KO mice compared with WT mice. Additionally, in WT mice, there was a greater level of pancreatic CSE expression and sulfide-synthesizing activity in caerulein-induced pancreatitis compared with the saline control. When comparing the two saline-treated control groups, we noted that the CSE KO mice showed significantly less pancreatic H2S-synthesizing activity relative to the WT mice. These results indicate that endogenous H2S generated by CSE plays a key proinflammatory role via NF-κB activation in caerulein-induced pancreatitis, and its genetic deletion affords significant protection against acute pancreatitis and associated lung injury.

Substance P participates in immune-mediated hepatic injury induced by concanavalin A in mice and stimulates cytokine synthesis in Kupffer cells

Studies have indicated that the immune system plays a pivotal role in hepatitis. Substance P (SP) has been shown to modulate the immune response. In order to investigate the role of SP in liver injury and to determine whether it leads to pro-inflammatory signaling, we established a mouse model of hepatic injury induced by concanavalin A (ConA). We also exposed mouse Kupffer cells (KCs) to SP in vitro. Cytokine and SP levels in liver homogenates were detected using enzyme-linked immunosorbent assay (ELISA) and the protective effects of L-703,606 were evaluated through serological and histological assessments. Neurokinin-1 receptor (NK-1R) expression was evaluated by immunofluorescence and quantitative polymerase chain reaction (PCR). The levels of SP, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly increased in the ConA-treated mice and the levels of ALT and AST were markedly reduced by L-703,606-pretreatment. Liver injury was significantly reduced by treatment with L-703,606. The mouse KCs expressed NK-1R and SP increased NK-1R mRNA expression. Furthermore, NK-1R blockade eliminated the effect of SP on NK-1R mRNA expression. The cytokine levels exhibited a substantial increase in the SP-pretreated KCs compared with the KCs that were cultured in control medium. The inter-leukin (IL)-6 and tumor necrosis factor (TNF)-α levels in the L-703,606-pretreated KCs were significantly lower compared with those in the SP-pretreated KCs. Our study suggests that neurogenic inflammation induced by SP plays an important role in hepatitis. Mouse KCs express NK-1R and SP increases NK-1R mRNA expression. SP enhances IL-6 and TNF-α secretion and an NK-1R antagonist inhibits this secretion.

Substance P decreases fat storage and increases adipocytokine production in 3T3-L1 adipocytes

Obesity, inflammation, and insulin resistance are closely linked. Substance P (SP), via its neurokinin 1 receptor (NK1R), mediates inflammatory and, possibly, neuroendocrine processes. We examined SP effects on lipid storage and cytokine production in 3T3-L1 adipocytes and adipose tissues. 3T3-L1 adipocytes and preadipocytes express NK1R, and 8 days of SP supplementation during differentiation to 3T3-L1 preadipocytes decreased lipid droplet accumulation. SP (10 nM, 24 h) increased lipolysis in primary adipocytes (138 ± 7%, P < 0.05) and reduced fatty acid uptake (-31 ± 7%, P < 0.05) and mRNA expression of the differentiation-related transcription factors peroxisome proliferator-activated receptor-γ type 2 (-64 ± 2%, P < 0.001) and CCAAT enhancer-binding protein (CEBP)-α (-65 ± 2%, P < 0.001) and the lipid storage genes fatty acid-binding protein type 4 (-59 ± 2%, P < 0.001) and diacylglycerol O-acyltransferase-1 (-45 ± 2%, P < 0.01) in 3T3-L1 adipocytes, while CD36, a fatty acid transporter (+82 ± 19%, P < 0.01), was augmented. SP increased secretion of complement C3 (148 ± 15%, P < 0.04), monocyte chemoattractant protein-1 (156 ± 16%, P < 0.03), and keratinocyte-derived chemokine (148 ± 18%, P = 0.045) in 3T3-L1 adipocytes and monocyte chemoattractant protein-1 (496 ± 142%, P < 0.02) and complement C3 (152 ± 25%, P < 0.04) in adipose tissue and primary adipocytes, respectively. These SP effects were accompanied by downregulation of insulin receptor substrate 1 (-82 ± 2%, P < 0.01) and GLUT4 (-76 ± 2%, P < 0.01) mRNA expression, and SP acutely blocked insulin-mediated stimulation of fatty acid uptake and Akt phosphorylation. Although adiponectin secretion was unchanged, mRNA expression was decreased (-86 ± 8%, P < 0.001). In humans, NK1R expression correlates positively with plasma insulin, fatty acid, and complement C3 and negatively with adiponectin, CEBPα, CEBPβ, and peroxisome proliferator-activated receptor-γ mRNA expression in omental, but not subcutaneous, adipose tissue. Our results suggest that, beyond its neuroendocrine and inflammatory effects, SP could also be involved in targeting adipose tissue and influencing insulin resistance.

Activation of neurokinin-1 receptors up-regulates substance P and neurokinin-1 receptor expression in murine pancreatic acinar cells

Acute pancreatitis (AP) has been associated with an up-regulation of substance P (SP) and neurokinin-1 receptor (NK1R) in the pancreas. Increased SP-NK1R interaction was suggested to be pro-inflammatory during AP. Previously, we showed that caerulein treatment increased SP/NK1R expression in mouse pancreatic acinar cells, but the effect of SP treatment was not evaluated. Pancreatic acinar cells were obtained from pancreas of male swiss mice (25–30 g). We measured mRNA expression of preprotachykinin-A (PPTA) and NK1R following treatment of SP (10⁻⁶M). SP treatment increased PPTA and NK1R expression in isolated pancreatic acinar cells, which was abolished by pretreatment of a selective NK1R antagonist, CP96,345. SP also time dependently increased protein expression of NK1R. Treatment of cells with a specific NK1R agonist, GR73,632, up-regulated SP protein levels in the cells. Using previously established concentrations, pre-treatment of pancreatic acinar cells with Gö6976 (10 nM), rottlerin (5 μM), PD98059 (30 μM), SP600125 (30 μM) or Bay11-7082 (30 μM) significantly inhibited up-regulation of SP and NK1R. These observations suggested that the PKC-ERK/JNK-NF-κB pathway is necessary for the modulation of expression levels. In comparison, pre-treatment of CP96,345 reversed gene expression in SP-induced cells, but not in caerulein-treated cells. Overall, the findings in this study suggested a possible auto-regulatory mechanism of SP/NK1R expression in mouse pancreatic acinar cells, via activation of NK1R. Elevated SP levels during AP might increase the occurrence of a positive feedback loop that contributes to abnormally high expression of SP and NK1R.

Role of hydrogen sulfide in the pathology of inflammation

Hydrogen sulfide (H2S) is a well-known toxic gas that is synthesized in the human body from the amino acids cystathionine, homocysteine, and cysteine by the action of at least two distinct enzymes: cystathionine-γ-lyase and cystathionine-β-synthase. In the past few years, H2S has emerged as a novel and increasingly important biological mediator. Imbalances in H2S have also been shown to be associated with various disease conditions. However, defining the precise pathophysiology of H2S is proving to be a complex challenge. Recent research in our laboratory has shown H2S as a novel mediator of inflammation and work in several groups worldwide is currently focused on determining the role of H2S in inflammation. H2S has been implicated in different inflammatory conditions, such as acute pancreatitis, sepsis, joint inflammation, and chronic obstructive pulmonary disease (COPD). Active research on the role of H2S in inflammation will unravel the pathophysiology of its actions in inflammatory conditions and may help develop novel therapeutic approaches for several, as yet incurable, disease conditions.

Islet organogenesis, angiogenesis and innervation

The pancreas is characterized by a major component, an exocrine and ductal system involved in digestion, and a minor component, the endocrine islets represented by islet micro-organs that tightly regulate glucose homoeostasis. Pancreatic organogenesis is strictly co-ordinated by transcription factors that are expressed sequentially to yield functional islets capable of maintaining glucose homoeostasis. Angiogenesis and innervation complete islet development, equipping islets to respond to metabolic demands. Proper regulation of this triad of processes during development is critical for establishing functional islets.

Substance P in the corneal stroma regulates the severity of herpetic stromal keratitis lesions

PURPOSE

To determine whether substance P (SP) in herpes simplex virus-1 (HSV-1) infected cornea regulates the severity of herpetic stromal keratitis (HSK) lesions in a mouse model.

METHODS

C57BL/6 mice were infected ocularly with HSV-1 (RE). The corneas with HSK lesions, on Day 15 postinfection, were grouped on the basis of the corneal opacity as mild (≤2) or severe (>2). The amount of SP was determined in the corneas with mild or severe HSK lesions by enzyme immunosorbent assay (EIA) and confocal microscopy. Subconjunctival inoculation of spantide I, SP receptor antagonist, was carried out during the clinical phase of HSK. ELISA and flow cytometry were used to determine the level of cytokines, chemokines, and influx of immune cell types in the corneal lesions.

RESULTS

The authors determined a significantly higher level of SP in the corneas with severe HSK lesions in comparison with mild lesions. The corneas with a higher level of SP also exhibited higher amounts of proinflammatory cytokines (IL-6, IFN-γ) and chemokines (CCL3, CXCL2) when compared with the corneas with a lower level of SP. SP receptor NK1R expression was determined in CD45- and CD45+ cells in infected cornea. SP present in the corneal stroma of the eyes with severe HSK lesions colocalized with β-III tubulin(+) and IA(b+) cell types. Subconjunctival inoculation of spantide I during the clinical phase of HSK resulted in significant reduction in the corneal opacity and angiogenesis.

CONCLUSIONS

Collectively, these results demonstrate the relative contribution of substance P in regulating the clinical severity of HSK lesions in a mouse model.

The role of neutral endopeptidase in caerulein-induced acute pancreatitis

Substance P (SP) is well known to promote inflammation in acute pancreatitis (AP) by interacting with neurokinin-1 receptor. However, mechanisms that terminate SP-mediated responses are unclear. Neutral endopeptidase (NEP) is a cell-surface enzyme that degrades SP in the extracellular fluid. In this study, we examined the expression and the role of NEP in caerulein-induced AP. Male BALB/c mice (20-25 g) subjected to 3-10 hourly injections of caerulein (50 μg/kg) exhibited reduced NEP activity and protein expression in the pancreas and lungs. Additionally, caerulein (10(-7) M) also downregulated NEP activity and mRNA expression in isolated pancreatic acinar cells. The role of NEP in AP was examined in two opposite ways: inhibition of NEP (phosphoramidon [5 mg/kg] or thiorphan [10 mg/kg]) followed by 6 hourly caerulein injections) or supplementation with exogenous NEP (10 hourly caerulein injections, treatment of recombinant mouse NEP [1 mg/kg] during second caerulein injection). Inhibition of NEP raised SP levels and exacerbated inflammatory conditions in mice. Meanwhile, the severity of AP, determined by histological examination, tissue water content, myeloperoxidase activity, and plasma amylase activity, was markedly better in mice that received exogenous NEP treatment. Our results suggest that NEP is anti-inflammatory in caerulein-induced AP. Acute inhibition of NEP contributes to increased SP levels in caerulein-induced AP, which leads to augmented inflammatory responses in the pancreas and associated lung injury.

Role of platelets in experimental acute pancreatitis

BACKGROUND

Platelets not only control thrombosis and haemostasis but may also regulate inflammatory processes. Acute pancreatitis (AP) is characterized by changes in both coagulation and proinflammatory activities. The role of platelets in AP is not yet known.

METHODS

AP was induced in C57BL/6 mice by repeated caerulein administration (50 µg/kg intraperitoneally). Mice received a platelet-depleting or control antibody before caerulein challenge. Neutrophil infiltration, myeloperoxidase (MPO) and macrophage inflammatory protein (MIP) 2 levels, acinar cell necrosis and haemorrhage in the pancreas, as well as serum amylase activity, were determined 24 h after caerulein injection. In an alternative model of pancreatitis, L-arginine (4 g/kg intraperitoneally) was given twice with an interval of 1 h and tissue samples were taken after 72 h [Correction added after online publication 29 September 2010: in the preceding sentence, 4 mg/kg was corrected to 4 g/kg].

RESULTS

Caerulein administration increased acinar cell necrosis, neutrophil infiltration, focal haemorrhage and serum amylase levels. Platelet depletion reduced acinar cell necrosis, haemorrhage and serum amylase levels in AP. Depletion of platelets decreased caerulein-induced MPO levels and neutrophil recruitment in the pancreas. Platelet depletion abolished caerulein-induced MIP-2 generation in the pancreas and circulation. The effects of platelet depletion on necrosis, neutrophils and MPO levels were confirmed in L-arginine-induced pancreatitis.

CONCLUSION

Platelets play a crucial role in AP by regulating neutrophil infiltration, most likely mediated by MIP-2 production in the pancreas.

The islet-acinar axis of the pancreas: more than just insulin

Although the role of the islets in the regulation of acinar cell function seemed a mystery to investigators who observed their dispersion among pancreatic acini, over time an appreciation for this intricate and unique structural arrangement has developed. The last three decades have witnessed a steadily growing understanding of the interrelationship of the endocrine and the exocrine pancreas. The islet innervation and vascular anatomy have been more fully characterized and provide an appropriate background for our current understanding. The interrelationship between the endocrine and exocrine pancreas is mediated by islet-derived hormones such as insulin and somatostatin, other humoral factors including pancreastatin and ghrelin, and also neurotransmitters (nitric oxide, peptide YY, substance P, and galanin) released by the nerves innervating the pancreas. Although considerable progress has been achieved, further work is required to fully delineate the complex interplay of the numerous mechanisms involved. This review aims to provide a comprehensive update of the current literature available, bringing together data gleaned from studies addressing the actions of individual hormones, humoral factors, and neurotransmitters on the regulation of amylase secretion from the acinar cell. This comprehensive view of the islet-acinar axis of the pancreas while acknowledging the dominant role played by insulin and somatostatin on exocrine secretion sheds light on the influence of the various neuropeptides on amylase secretion.

PKC δ mediates pro-inflammatory responses in a mouse model of caerulein-induced acute pancreatitis

Acute pancreatitis is an inflammatory disorder of the pancreas. Protein kinase C (PKC) δ plays an important role in mediating chemokine production in mouse pancreatic acinar cells. This study aims to investigate the role of PKC δ in the pathogenesis of acute pancreatitis and to explore the mechanisms through which PKC δ mediates pro-inflammatory signaling. Acute pancreatitis was induced in mice by ten hourly intraperitoneal injections of caerulein. PKC δ translocation inhibitor peptide (δV1-1) at a dose of 1.0 mg/kg or Tat (carrier peptide) at a dose of 1.0 mg/kg was administered to mice either 1 h before or 1 h after the first caerulein injection. One hour after the last caerulein injection, the mice were killed and pancreas, lungs, and blood were collected. Prophylactic and therapeutic treatment with δV1-1 attenuated caerulein-induced plasma amylase levels and pancreatic edema. Treatment with δV1-1 decreased myeloperoxidase activity and monocyte chemotactic protein-1 levels in both pancreas and plasma. PKC δ mediated acute pancreatitis by activating pancreatic nuclear factor κB, activator protein-1, and mitogen-activated protein kinases. Moreover, blockade of PKC δ attenuated lung myeloperoxidase activity and edema. Histological examination of pancreatic and lung sections confirmed protection against acute pancreatitis. Treatment with Tat had no protective effect on acute pancreatitis. Blockade of PKC δ represents a promising prophylactic and/or therapeutic tool for the treatment of acute pancreatitis.

Hydrogen sulfide and substance P in inflammation

Hydrogen sulfide (H(2)S) plays an important role in cardiovascular, central nervous, and gastrointestinal systems. Being the third gaseous mediator, H(2)S has been shown to act as a vasodilator. In recent times, more and more attention has been paid to the biological functions of H(2)S in inflammation. Substance P is an 11 amino acid neuropeptide that is released from nerve endings in many tissues. Subsequent to its release, substance P binds to neurokinin-1 (NK-1) receptors on the surface of effector cells and, in addition to being a mediator of pain, it plays an important role in many inflammatory states including asthma, immune-complex-mediated lung injury, experimental arthritis, and inflammatory bowel disease. Substance P has been shown to increase microvascular permeability and promote plasma extravasation. Using animal models of inflammation of different etiologies such as acute pancreatitis, sepsis, and burns, studies in our laboratory have recently shown an important role of the pro-inflammatory action of H(2)S and substance P.

Inflammatory role of the acinar cells during acute pancreatitis

Pancreatic acinar cells are secretory cells whose main function is to synthesize, store and finally release digestive enzymes into the duodenum. However, in response to noxious stimuli, acinar cells behave like real inflammatory cells because of their ability to activate signalling transduction pathways involved in the expression of inflammatory mediators. Mediated by the kinase cascade, activation of Nuclear factor-κB, Activating factor-1 and Signal transducers and activators of transcription transcription factors has been demonstrated in acinar cells, resulting in overexpression of inflammatory genes. In turn, kinase activity is down-regulated by protein phosphatases and the final balance between kinase and phosphatase activity will determine the capability of the acinar cells to produce inflammatory factors. The kinase/phosphatase pair is a redox-sensitive system in which kinase activation overwhelms phosphatase activity under oxidant conditions. Thus, the oxidative stress developed within acinar cells at early stages of acute pancreatitis triggers the activation of signalling pathways involved in the up-regulation of cytokines, chemokines and adhesion molecules. In this way, acinar cells trigger the release of the first inflammatory signals which can mediate the activation and recruitment of circulating inflammatory cells into the injured pancreas. Accordingly, the role of acinar cells as promoters of the inflammatory response in acute pancreatitis may be considered. This concept leads to amplifying the focus from leukocyte to acinar cells themselves, to explain the local inflammation in early pancreatitis.

The combination of neurokinin-1 and galanin receptor antagonists ameliorates caerulein-induced acute pancreatitis in mice

Both galanin and substance P have been separately implicated in the pathogenesis of acute pancreatitis. We compared the efficacy of the combination of the galanin antagonist galantide and the neurokinin-1 receptor antagonist L703,606 with that of either alone in the treatment of acute pancreatitis. Acute pancreatitis was induced in mice with 7-hourly caerulein injections. Galantide was co-administered with each caerulein injection commencing with the first injection (prophylactic) or 2h after the first injection (therapeutic). L703,606 was administered either 30 min before (prophylactic), or 2h after the first caerulein injection (therapeutic). Combination of the two agents was also administered. Control groups received galantide, L703,606, or saline, without caerulein. Pancreata were harvested for histological examination and estimation of myeloperoxidase activity. Plasma amylase activity was measured. Prophylactic and therapeutic administration of galantide reduced the hyperamylasemia by 37% and 30% respectively whereas only prophylactic L703,606 reduced hyperamylasemia (by 34%). Prophylactic administration of the combined antagonists reduced the hyperamylasemia by 44%. In contrast, therapeutic administration of the combination significantly increased plasma amylase levels by 27%. The plasma amylase activity in the control groups was similar to basal levels. Prophylactic and therapeutic administration of either antagonist or the combination significantly reduced myeloperoxidase activity. Galantide and L703,606 individually, and in combination, significantly reduced the acute pancreatitis-induced necrosis score. The administration of the combined antagonists does not offer any further benefit as compared to galantide alone. An interaction between neurokinin-1 and galanin receptors may occur to modulate amylase secretion.

Extracellular signal-regulated kinase 1/2 and c-Jun NH2-terminal kinase, through nuclear factor-kappaB and activator protein-1, contribute to caerulein-induced expression of substance P and neurokinin-1 receptors in pancreatic acinar cells

The neuropeptide substance P (SP) has emerged to be an important proinflammatory mediator in acute pancreatitis (AP). The presence of substance P and its receptor, neurokinin-1 receptor (NK1R) has been shown in the pancreas and the pancreatic acinar cells. In this study, we investigated the unexplored mechanisms that mediate SP and NK1R expression using an in vitro AP model. Pancreatic acinar cells were obtained from pancreas of male Swiss mice. Isolated cells were treated with caerulein to mimic secretagogue pancreatitis. A concentration-dependent study that subjected the cells to 60 min of stimulation by caerulein showed that SP and the transcript from its gene preprotachykinin-A (PPT-A), and NK1R were up-regulated at a supraphysiological concentration of 10(-7) M. A concentration-dependent study on intracellular kinases, extracellular signal-regulated kinase (ERK1/2), and c-Jun N-terminal kinase (JNK) and also transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) showed that they were activated when the caerulein concentration was 10(-7) M. Inhibition of JNK reversed the up-regulation of PPT-A, SP, and NK1R. However, inhibition of ERK1/2 reversed the up-regulation of NK1R but not of PPT-A and SP. Furthermore, we found that specific ERK1/2 and JNK inhibitors reduce NF-kappaB and AP-1 activity. Taken together, our results suggest that supraphysiological concentrations of caerulein up-regulate the expression of SP and NK1R in pancreatic acinar cells, and the signaling molecules that are involved in this up-regulation include ERK1/2, JNK, NF-kappaB, and AP-1.

Mechanisms of dexamethasone-mediated chemokine down-regulation in mild and severe acute pancreatitis

This study aimed to investigate the role of therapeutic dexamethasone (Dex) treatment on the mechanisms underlying chemokine expression during mild and severe acute pancreatitis (AP) experimentally induced in rats. Regardless of the AP severity, Dex (1 mg/kg), administered 1 h after AP, reduced the acinar cell activation of extracellular signal-regulated kinase (ERK) and c-Jun-NH(2)-terminal kinase (JNK) but failed to reduce p38-mitogen-activated protein kinase (MAPK) in severe AP. In both AP models, Dex inhibited the activation of nuclear factor-kappaB (NF-kappaB) and signal transducers and activators of transcription (STAT) factors. All of this resulted in pancreatic down-regulation of the chemokines monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant (CINC). Lower plasma chemokine levels as well as decreased amylasemia, hematocrit and plasma interleukin-1beta (Il-1beta) levels were found either in mild or severe AP treated with Dex. Pancreatic neutrophil infiltration was attenuated by Dex in mild but not in severe AP. In conclusion, by targeting MAPKs, NF-kappaB and STAT3 pathways, Dex treatment down-regulated the chemokine expression in different cell sources during mild and severe AP, resulting in decreased severity of the disease.

Involvement of SRC family kinases in substance P-induced chemokine production in mouse pancreatic acinar cells and its significance in acute pancreatitis

Substance P is known to play a key role in the pathogenesis of acute pancreatitis. Src family kinases (SFKs) are known to be involved in cytokine signaling. However, the involvement of SFKs in substance P-induced chemokine production and its role in acute pancreatitis have not been investigated yet. To that end, we have used primary preparations of mouse pancreatic acinar cells as our model to show that substance P/neurokinin 1 receptor (NK1R) induced activation of SFKs. SFKs mediated the activation of mitogen-activated protein kinases [extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK)], transcription factors [signal transducer and activator of transcription (STAT) 3, nuclear factor (NF) kappaB, activator protein-1 (AP-1)], and production of chemokines in pancreatic acinar cells. We further tested the significance of the SFK signaling pathway in acute pancreatitis. Our results show, for the first time, that treatment of mice with the potent and selective SFK inhibitor PP2 [4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo [3,4-D] pyrimidine], but not its negative inhibitor PP3 (4-amino-7-phenylpyrazol [3,4-D] pyrimidine), reduced the severity of pancreatitis. This was proven by significant attenuation of hyperamylasemia, pancreatic myeloperoxidase activity, chemokines, and water content. Histological evidence of diminished pancreatic injury also confirmed the protective effect of the inhibition of SFKs. Moreover, treatment with the substance P receptor antagonist CP96345 [(2S,3S)-cis-2-(diphenylmethyl)-N-((2-methoxyphenyl)-methyl)-1-azabicyclo(2.2.2.)-octan-3-amine] attenuated acute pancreatitis-induced activation of SFKs, ERK, JNK, STAT3, NFkappaB, and AP-1. The proposed signaling pathway through which substance P mediates acute pancreatitis is through substance P/NK1R-SFKs-(ERK, JNK)-(STAT3, NFkappaB, AP-1) chemokines. In light of our study, we propose that drugs targeting the substance P-mediated signaling pathways could prove beneficial in improving treatment efficacy in acute pancreatitis.

The role of redox status on chemokine expression in acute pancreatitis

This study focused on the involvement of oxidative stress in the mechanisms mediating chemokine production in different cell sources during mild and severe acute pancreatitis (AP) induced by bile-pancreatic duct obstruction (BPDO) and 3.5% NaTc, respectively. N-Acetylcysteine (NAC) was used as antioxidant treatment. Pancreatic glutathione depletion, acinar overexpression of monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant (CINC), and activation of p38MAPK, NF-kappaB and STAT3 were found in both AP models. NAC reduced the depletion of glutathione in BPDO- but not in NaTc-induced AP, in which oxidative stress overwhelmed the antioxidant capability of NAC. As a result, inhibition of the acinar chemokine expression and signalling pathways occurs in mild, but not in severe AP. However, MCP-1 and CINC expressions in whole pancreas and plasma chemokine levels were not reduced by NAC, even in BPDO-induced AP, suggesting that in addition to acini, other pancreatic cells produced chemokines by antioxidant resistant mechanisms. The high Il-6 plasma levels found during AP, both in NAC-treated and non-treated rats, pointed out cytokines as activating factors of chemokine expression in non-acinar cells. In conclusion, from early AP oxidant-mediated MAPK, NF-kappaB and STAT3 activation triggers the chemokine expression in acini but not in non-acinar cells.

Cell penetrating peptide inhibitors of nuclear factor-kappa B

The nuclear factor kappa B (NF-kappaB) transcription factors are activated by a range of stimuli including pro-inflammatory cytokines. Active NF-kappaB regulates the expression of genes involved in inflammation and cell survival and aberrant NF-kappaB activity plays pathological roles in certain types of cancer and diseases characterized by chronic inflammation. NF-kappaB signaling is an attractive target for the development of novel anti-inflammatory or anti-cancer drugs and we discuss here how the method of peptide transduction has been used to specifically target NF-kappaB. Peptide transduction relies on the ability of certain small cell-penetrating peptides (CPPs) to enter cells, and a panel of CPP-linked inhibitors (CPP-Is) has been developed to directly inhibit NF-kappaB signaling. Remarkably, several of these NF-kappaB-targeting CPP-Is are effective in vivo and therefore offer exciting potential in the clinical setting.

Pro-inflammatory effects of hydrogen sulphide on substance P in caerulein-induced acute pancreatitis

Hydrogen sulphide (H₂S), a novel gasotransmitter, has been recognized to play an important role in inflammation. Cystathionine-γ-lyase (CSE) is a major H₂S synthesizing enzyme in the cardiovascular system and DL-propargylglycine (PAG) is an irreversible inhibitor of CSE. Substance P (SP), a product of preprotachykinin-A (PPT-A) gene, is a well-known pro-inflammatory mediator which acts principally through the neurokinin-1 receptor (NK-1R). We have shown an association between H₂S and SP in pulmonary inflammation as well as a pro-inflammatory role of H₂S and SP in acute pancreatitis. The present study was aimed to investigate the interplay between pro-inflammatory effects of H₂S and SP in a murine model of caerulein-induced acute pancreatitis. Acute pancreatitis was induced in mice by 10 hourly intraperitoneal injections of caerulein (50 (g/kg). PAG (100 mg/kg, i.p.) was administered either 1 hr before (prophylactic) or 1 hr after (therapeutic) the first caerulein injection. PAG, given prophylactically as well as therapeutically, significantly reduced plasma H₂S levels and pancreatic H₂S synthesizing activities as well as SP concentrations in plasma, pancreas and lung compared with caerulein-induced acute pancreatitis. Furthermore, prophylactic as well as therapeutic administration of PAG significantly reduced PPT-A mRNA expression and NK-1R mRNA expression in both pancreas and lung when compared with caerulein-induced acute pancreatitis. These results suggest that the pro-inflammatory effects of H₂S may be mediated by SP-NK-1R pathway in acute pancreatitis.

Neurokinin A engages neurokinin-1 receptor to induce NF-κB-dependent gene expression in murine macrophages: implications of ERK1/2 and PI 3-kinase/Akt pathways

Neurokinin A (NKA) belongs to the tachykinin neuropeptide family. Its biological functions are primarily mediated by the neurokinin (NK)-2 receptor. NKA has been implicated in several inflammatory conditions. However, there are limited data about the mechanism of its pathogenetic action. Here, we investigated proinflammatory effects of NKA on peripheral immune cells using the mouse macrophage/monocyte cell line RAW 264.7 and primary peritoneal macrophages. The signaling mechanistic pathways involved were also studied. In mouse macrophages with no detectable NK-2 receptors, NKA induces the upregulation of NK-1 but not NK-2 receptor expression. Furthermore, NKA engages this NK-1 receptor, resulting in inflammatory-like responses involving activation of the transcription factor nuclear factor (NF)-κB and induction of NF-κB-responsive proinflammatory chemokine expression. NKA activates NF-κB as evidenced by induced phosphorylation (leading to degradation) of its inhibitory protein IκBα, increased cellular levels of the transactivation-active phospho(Ser276)-p65 and its nuclear translocation, as well as enhanced DNA-binding activity of NF-κB. These responses are specifically inhibited by selective NK-1 receptor antagonists but not NK-2 receptor antagonists, thereby excluding the role of NK-2 receptor. Further investigation on the upstream signaling mechanisms suggests that two NF-κB-activating pathways (extracellular signal-regulated kinase 1/2 and phosphatidylinositol 3-kinase/protein kinase B) are activated by NKA. Specific inhibitors of the two pathways block NF-κB-dependent chemokine expression. The inhibitory effects are mediated through regulation of nuclear translocation, DNA-binding activity, and/or transactivation activity of NF-κB. Together, we provide novel evidence that NKA engages NK-1 receptors on mouse macrophages to elicit NF-κB-dependent cellular responses. The findings reveal cellular mechanisms that may underlie NKA-mediated inflammatory and immunological conditions.

Effect of mitogen-activated protein kinases on chemokine synthesis induced by substance P in mouse pancreatic acinar cells

Substance P, acting via its neurokinin 1 receptor (NK1 R), plays an important role in mediating a variety of inflammatory processes. Its interaction with chemokines is known to play a crucial role in the pathogenesis of acute pancreatitis. In pancreatic acinar cells, substance P stimulates the release of NFκB-driven chemokines. However, the signal transduction pathways by which substance P-NK1 R interaction induces chemokine production are still unclear. To that end, we went on to examine the participation of mitogen-activated protein kinases (MAPKs) in substance P-induced synthesis of pro-inflammatory chemokines, monocyte chemoanractant protein-1 (MCP-I), macrophage inflammatory protein-lα (MIP-lα) and macrophage inflammatory protein-2 (MIP-2), in pancreatic acini. In this study, we observed a time-dependent activation of ERK1/2, c-Jun N-terminal kinase (JNK), NFκB and activator protein-1 (AP-1) when pancreatic acini were stimulated with substance P. Moreover, substance P-induced ERK 1/2, JNK, NFκB and AP-1 activation as well as chemokine synthesis were blocked by pre-treatment with either extracellular signal-regulated protein kinase kinase 1 (MEK1) inhibitor or JNK inhibitor. In addition, substance P-induced activation of ERK 112, JNK, NFκB and AP-1-driven chemokine production were attenuated by CP96345, a selective NK1 R antagonist, in pancreatic acinar cells. Taken together, these results suggest that substance P-NK1 R induced chemokine production depends on the activation of MAPKs-mediated NFκB and AP-1 signalling pathways in mouse pancreatic acini.

Role of calcium in substance P-induced chemokine synthesis in mouse pancreatic acinar cells

BACKGROUND AND PURPOSE

Substance P (SP) and chemokines play critical roles in acute pancreatitis. SP elevates cytosolic calcium in pancreatic acinar cells and elevated cytosolic calcium is thought to be an early event in the pathogenesis of acute pancreatitis. SP induces production of chemokines MCP-1, MIP-1alpha and MIP-2 in pancreatic acinar cells, however the exact mechanism by which SP stimulates the production of these pro-inflammatory mediators remain undetermined. The aim of the present study is to investigate the role of calcium in SP-induced chemokine production in pancreatic acinar cells and to establish the signal transduction mechanisms involved.

EXPERIMENTAL APPROACH

An in vitro model of isolated mouse pancreatic acinar cells was used. Western blotting analysis, ELISA and calcium measurement were performed.

KEY RESULTS

SP increased chemokine secretion through the activation of PKCalpha/betaII, MAPKinases (ERK and JNK), NFkappaB and AP-1 in pancreatic acinar cells. These effects were blocked by pretreatment of the cells with the specific calcium chelator BAPTA-AM. Moreover, SP-induced activation of PKCalpha/betaII, ERK, JNK, NF-kappaB, AP-1 and chemokine production was inhibited by the specific phospholipase C inhibitor U73122.

CONCLUSIONS AND IMPLICATIONS

SP-induced chemokine production in pancreatic acinar cells resulted from PLC-induced elevated intracellular calcium and PKCalpha/betaII activation, subsequently leading to the activation of MAPKinases (ERK and JNK) and transcription factors NF-kappaB and AP-1. The present study demonstrates the critical role of calcium in SP-induced chemokine production in pancreatic acinar cells. Drugs targeting the SP-calcium mediated signaling pathways could prove beneficial in improving the treatment of acute pancreatitis.

Inhibition of hydrogen sulfide synthesis attenuates chemokine production and protects mice against acute pancreatitis and associated lung injury

OBJECTIVES

The present study investigated whether chemokines are involved in hydrogen sulfide (H2S)-associated pathogenesis of acute pancreatitis and associated lung injury.

METHODS

We have examined the effect of DL-propargylglycine, a cystathionine gamma-lyase inhibitor, on the synthesis of CC chemokine monocyte chemotactic protein 1, Regulated upon Activation, Normal T-cell Expressed, and Secreted, and macrophage inflammatory protein-1alpha (MIP-1alpha), and CXC chemokine MIP-2 in an in vitro and in vivo model of cerulein-induced acute pancreatitis and associated lung injury. In addition, the pancreatic acinar cells were treated with H2S donor drug, sodium hydrosulfide. The expression of these chemokines in the pancreatic acini, pancreas, and lungs was determined by quantitative real-time reverse transcriptase polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemistry.

RESULTS

After treatment with DL-propargylglycine, reverse transcriptase polymerase chain reaction, and enzyme-linked immunosorbent assay demonstrated down-regulation of cerulein-induced increase in monocyte chemotactic protein 1, MIP-1alpha, and MIP-2 expression but had no apparent effect on Regulated upon Activation, Normal T-cell Expressed, and Secreted expression.

CONCLUSIONS

These results suggest that the proinflammatory effect of H2S may be mediated by chemokines.

Relation of circulating concentrations of chemokine receptor CCR5 ligands to C-peptide, proinsulin and HbA1c and disease progression in type 1 diabetes

Th1 related chemokines CCL3 and CCL5 and Th2 related CCL4 as ligands of the receptor CCR5 contribute to disease development in animal models of type 1 diabetes. In humans, no data are available addressing the role of these chemokines regarding disease progression and remission. We investigated longitudinally circulating concentrations of CCR5 ligands of 256 newly diagnosed patients with type 1 diabetes. CCR5 ligands were differentially associated with beta-cell function and clinical remission. CCL5 was decreased in remitters and positively associated with HbA1c suggestive of a Th1 associated progression of the disease. Likewise, CCL3 was negatively related to C-peptide and positively associated with the beta-cell stress marker proinsulin but increased in remitters. CCL4 associated with decreased beta-cell stress shown by negative association with proinsulin. Blockage of chemokines or antagonism of CCR5 by therapeutic agents such as maraviroc may provide a new therapeutic target to ameliorate disease progression in type 1 diabetes.

Role of PKC-delta on substance P-induced chemokine synthesis in pancreatic acinar cells

Interaction of the neuropeptide substance P (SP) with its high-affinity neurokinin-1 receptor (NK1R) plays an important role in the pathophysiology of acute pancreatitis. SP is known to stimulate the production of chemokines monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1 alpha, and MIP-2 in pancreatic acinar cells via the activation of NF-kappaB. However, the signaling mechanisms by which the SP-NK1R interaction induces NF-kappaB activation and chemokine production remain unclear. To that end, in the present study, we investigated the participation of PKC in SP-induced chemokine production in pancreatic acinar cells. In this study, we showed that SP stimulated an early phosphorylation of PKC isoform PKC-delta followed by increased activation of MAPKKK MEKK1 and MAPK ERK and JNK as well as transcription factor NF-kappaB and activator protein-1 driven chemokine production. Depletion of PKC-delta with its inhibitor rottlerin or the specific PKC-delta translocation inhibitor peptide dose dependently decreased SP-induced PKC-delta, MEKK1, ERK, JNK, NF-kappaB, and AP-1 activation. Moreover, rottlerin as well as PKC-delta translocation inhibitor inhibited SP-induced chemokine production in a concentration-dependent manner. We also demonstrated that PKC-delta activation was attenuated by CP96345, a selective NK1R antagonist, thus showing that PKC-delta activation was indeed mediated by SP in pancreatic acinar cells. These results show that PKC-delta is an important proinflammatory signal transducer for SP-NK1R-induced chemokine production in pancreatic acinar cells.

Neuropeptide substance P upregulates chemokine and chemokine receptor expression in primary mouse neutrophils

Neuropeptides play an important role in the active communication between the nervous and immune systems. Substance P (SP) is a prominent neuropeptide involved in neurogenic inflammation and has been reported to exert various proinflammatory actions on inflammatory leukocytes including neutrophils. The present study further investigated the modulatory effect of SP (1 muM) on chemokine production and chemokine receptor expression in primary mouse neutrophils. Our results showed that SP primed neutrophils for chemotactic responses not only to the CXC chemokine macrophage inflammatory protein (MIP)-2/CXCL2 but also to the CC chemokine MIP-1alpha/CCL3. The activating effect of SP on neutrophils was further evidenced by upregulation of the CD11b integrin, the activation marker of neutrophils. SP induced both the mRNA and protein expression of the chemokines MIP-1alpha/CCL3 and MIP-2/CXCL2 in neutrophils and upregulated the chemokine receptors CC chemokine receptor (CCR)-1 and CXC chemokine receptor (CXCR)-2. This stimulatory effect on chemokine and chemokine receptor expression in neutrophils was further found to be neurokinin-1 receptor (NK-1R) specific. Pretreatment with selective NK-1R antagonists inhibited SP-triggered activation of neutrophils and chemokine and chemokine receptor upregulation. Moreover, SP-induced chemokine upregulation was NF-kappaB dependent. SP time dependently induced NF-kappaB p65 binding activity, IkappaBalpha degradation, and NF-kappaB p65 nuclear translocation in neutrophils. Inhibition of NF-kappaB activation with its inhibitor Bay11-7082 (10 muM) abolished SP-induced NF-kappaB binding activity and upregulation of MIP-1alpha/CCL3 and MIP-2/CXCL2 in neutrophils. Together, these results suggest that SP exerts a direct stimulatory effect on the expression of chemokines and chemokine receptors in mouse neutrophils. The effect is NK-1R mediated, involving NF-kappaB activation.

Loss of exocrine pancreatic stimulation during parenteral feeding suppresses digestive enzyme expression and induces Hsp70 expression

Luminal nutrients are essential for the growth and maintenance of digestive tissue including the pancreas and small intestinal mucosa. Long-term loss of luminal nutrients such as during animal hibernation has been shown to result in mucosal atrophy and a corresponding stress response characterized by the induction of heat shock protein (Hsp)70 expression. This study was conducted to determine if the loss of luminal nutrients during total parenteral nutrition (TPN) would result in atrophy of the exocrine pancreas and small intestinal mucosa as well as an induction of Hsp70 expression in rats. In experiment 1, the treatment groups included an orally fed control, a saline-infused surgical control, or TPN treatment for 7 days. In experiment 2, the treatment groups included an orally fed control and TPN alone or coinfused with varying doses of glucagon-like peptide (GLP)-2, a mucosal proliferation agent, for 7 days. In experiment 1, TPN resulted in a 40% reduction in pancreatic mass that was associated with a dramatic reduction in digestive enzyme expression, enhanced apoptosis, and a 200% increase in Hsp70 expression. Conversely, heat shock cognate 70, Hsp27, and Hsp60 expression was not changed in the pancreas. In experiment 2, TPN resulted in a 30% reduction in jejunal mucosa mass and a similar induction of Hsp70 expression. The inclusion of GLP-2 during TPN attenuated jejunal mucosal atrophy and inhibited Hsp70 expression, suggesting that Hsp70 induction is sensitive to cell growth. These data indicate that pancreatic and intestinal mucosal atrophy caused by a loss of luminal nutrient stimulation is accompanied by a compensatory response involving Hsp70.