Pancreatitis-associated protein 2 modulates inflammatory responses in macrophages

Development and validation of an ELISA to measure regenerating island-derived protein 3E in canine blood

BACKGROUND

Regenerating island-derived proteins (REG) are upregulated in people with sepsis, pancreatitis, and gastrointestinal diseases. One member of the REG family, namely REG3E, was recently identified in pancreatic tissue and plasma of dogs, with high expression in pancreatitis and sepsis.

OBJECTIVES

We aimed to develop and validate an ELISA to measure REG3E concentrations in canine blood.

METHODS

An indirect sandwich ELISA was developed using recombinant canine REG3E protein and polyclonal anti-canine REG3E antibodies raised in guinea pigs and rabbits. Antibody specificity was assessed using western blot and mass spectrometric analysis of protein purified from canine plasma. Assay validation included evaluation of dilutional linearity, parallelism, spiking recovery, repeatability and reproducibility, stability, interferences, and comparison of serum and heparinized plasma.

RESULTS

Antibodies bound specifically to REG3E with no evidence of cross-reactivity with other proteins. The limit of detection of the ELISA was 15 ng/mL, and the lower limit of quantification was 30 ng/mL. The assay demonstrated good to excellent linearity, dilutional and mixing parallelism, and recovery, with mean observed-to-expected ratios of 104%, 107%, 102%, and 92%, respectively, and no evidence of a hook effect. Coefficients of variation were ≤8.5% for repeatability and ≤14.3% for reproducibility at three different levels. Measurements of REG3E in plasma were not significantly influenced by different storage conditions, freeze-thawing cycles, hemolysis, lipemia, or icterus. There was no significant difference between REG3E concentrations in heparinized plasma and serum samples.

CONCLUSIONS

The canine REG3E ELISA has acceptable precision, accuracy, linearity, and reproducibility for the measurement of REG3E in canine plasma and serum.

Antimicrobial protein REG3A and signaling networks are predictive of stroke outcomes

Regenerating Family Member 3 Alpha (REG3A) is a multifunctional protein with antimicrobial activity, and primarily secreted by the intestine and pancreas. Studies have shown an increased expression of REG3A in systemic inflammatory responses to acute injury and infection, but studies investigating REG3A during the pathogenesis of ischemic stroke are limited. The aims of this study were to examine the associations between arterial expression of REG3A and other arterial inflammatory proteins implicated in stroke pathogenesis, as well as associations between REG3A and markers of poor outcome for ischemic stroke. The University of Kentucky Blood and Clot Thrombectomy Registry and Collaboration (BACTRAC) protocol (clinicaltrials.gov NCT03153683) utilizes thrombectomy to isolate intracranial arterial blood (i.e. distal to thrombus) and systemic arterial blood (i.e. carotid). Samples were analyzed by Olink Proteomics for N = 42 subjects. Statistical analyses of plasma proteins included 2-sample t-tests, spearman and biserial correlations, and robust regression models to elucidate network signaling and association to clinical outcomes. Results indicated that levels of systemic REG3A were positively correlated with inflammatory proteins interleukin IL6 (R = 0.344, p = 0.030) and IL17C (R = 0.468, p = 0.002). 2-sided t- tests examining differences of systemic REG3A within quartiles of NIHSS admission score depicted significant differences between quartiles. Those with NIHSS scores corresponding to moderate and moderate-severe neurofunctional deficits had significantly higher levels of systemic REG3A compared to those with NIHSS scores corresponding to mild and mild-moderate neurofunctional deficits (p = 0.016). STRING analyses of proteins in each robust regression model demonstrated substantial networking between REG3A and other systemic proteins highly relevant to ischemic stroke. The present study provides novel data on systemic REG3A in the context of ischemic stroke. These results demonstrate the influential role of REG3A regarding surrogate functional and radiographic outcomes of stroke severity. Additionally, they provide novel insight into the role of REG3A and related proteins during the complex neuroinflammatory process of ischemic stroke. These data provide a foundation for future studies to investigate REG3A and related networking proteins as potential biomarkers with prognostic potential, as well as potential therapeutic targets.

Transcriptome analysis to elucidate the toxicity mechanisms of fenvalerate, sulfide gatifloxacin, and ridomil on the hepatopancreas of Procambarus clarkii

Most antibiotics, insecticides, and other chemicals used in agricultural and fishery production tend to persist in the environment. Fenvalerate, sulfide gatifloxacin, and ridomil are widely used in aquaculture as antibacterial, antifungal, and antiparasitic drugs; however, their toxicity mechanism remains unclear. Thus, we herein analyzed the effects of these three drugs on the hepatopancreas of Procambarus clarkii at the transcriptome level. Twelve normalized cDNA libraries were constructed using RNA extracted from P. clarkii after treatment with fenvalerate, sulfide gatifloxacin, or ridomil and from an untreated control group, followed by Kyoto Encyclopedia of Genes and Genomes pathway analysis. In the control vs fenvalerate and control vs sulfide gatifloxacin groups, 14 and seven pathways were significantly enriched, respectively. Further, the effects of fenvalerate and sulfide gatifloxacin were similar on the hepatopancreas of P. clarkii. We also found that the expression level of genes encoding senescence marker protein-30 and arylsulfatase A was downregulated in the sulfide gatifloxacin group, indicating that sulfide gatifloxacin accelerated the apoptosis of hepatopancreatocytes. The expression level of major facilitator superfamily domain containing 10 was downregulated, implying that it interferes with the ability of the hepatopancreas to metabolize drugs. Interestingly, we found that Niemann pick type C1 and glucosylceramidase-β potentially interact with each other, consequently decreasing the antioxidant capacity of P. clarkii hepatopancreas. In the fenvalerate group, the downregulation of the expression level of xanthine dehydrogenase indicated that fenvalerate affected the immune system of P. clarkii; moreover, the upregulation of the expression level of pancreatitis-associated protein-2 and cathepsin C indicated that fenvalerate caused possible inflammatory pathological injury to P. clarkii hepatopancreas. In the ridomil group, no pathway was significantly enriched. In total, 21 genes showed significant differences in all three groups. To conclude, although there appears to be some overlap in the toxicity mechanisms of fenvalerate, sulfide gatifloxacin, and ridomil, further studies are warranted.

Role of regenerating islet-derived proteins in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an inflammatory disorder of the gastrointestinal tract that affects millions of patients worldwide. It has a complex and multifactorial etiology leading to excessive exposure of intestinal epithelium to microbial antigens, inappropriate activation of the immune system and ultimately to the damage of intestinal tissues. Although numerous efforts have been made to improve the disease management, IBD remains persistently recurring and beyond cure. This is due largely to the gaps in our understanding of the pathogenesis of IBD that hamper the development of timely diagnoses and effective treatment. However, some recent discoveries, including the beneficial effects of interleukin-22 (IL-22) on the inflamed intestine, have shed light on a self-protective mechanism in IBD. Regenerating islet-derived (REG/Reg) proteins are small secretory proteins which function as IL-22's downstream effectors. Mounting studies have demonstrated that IBD patients have significantly increased REG expressions in the injured intestine, but with undefined mechanisms and roles. The reported functions of REG/Reg proteins in intestinal homeostasis, such as those of antibacterial, anti-inflammatory and tissue repair, lead us to discuss their potential mechanisms and clinical relevance in IBD in order to advance IBD research and management.

Nerve Injury-Induced Neuronal PAP-I Maintains Neuropathic Pain by Activating Spinal Microglia

Pancreatitis-associated proteins (PAPs) display multiple functions in visceral diseases. Previous studies showed that the expression level of PAP-I was low in the DRG of naive rats but was de novo expressed after peripheral nerve injury. However, its role in neuropathic pain remains unknown. We found that PAP-I expression was continuously upregulated in the DRG neurons from rat spared nerve injury models, and transported toward the spinal dorsal horn to act as a proinflammatory factor. Intrathecal delivery of PAP-I enhanced sensory hyperalgesia, whereas PAP-I deficiency by either gene knockout or antibody application alleviated tactile allodynia at the maintenance phase after spared nerve injury. Furthermore, PAP-I functioned by activating the spinal microglia via C-C chemokine receptor Type 2 that participated in neuropathic pain. Inhibition of either microglial activation or C-C chemokine receptor Type 2 abolished the PAP-I-induced hyperalgesia. Thus, PAP-I mediates the neuron-microglial crosstalk after peripheral nerve injury and contributes to the maintenance of neuropathic pain.SIGNIFICANCE STATEMENT Neuropathic pain is maladaptive pain condition, and the maintaining mechanism is largely unclear. Here we reveal that, after peripheral nerve injury, PAP-I can be transported to the spinal dorsal horn and is crucial in the progression of neuropathic pain. Importantly, we prove that PAP-I mainly functions through activating the spinal microglia via the CCR2-p38 MAPK pathway. Furthermore, we confirm that the proinflammatory effect of PAP-I is more prominent after the establishment of neuropathic pain, thus indicating that microglia also participate in the maintenance phase of neuropathic pain.

Protective effects of HTD4010, a Reg3α/PAP-derived peptide, in mouse model of acute pancreatitis via toll-like receptor 4 pathway

Acute pancreatitis (AP) is one of the most common digestive tract diseases, but effective drug therapy is still lack. Regenerating gene protein 3α (Reg3α) administration significantly reduced the severity of AP in mice. HTD4010 is a new 15 amino acid long synthetic peptide and its biological activities are similar to Reg3α. This study aimed to explore whether HTD4010 could protect pancreatic acinar cells against necrosis and decrease the inflammatory response in AP, and thus to explore underlying mechanisms. It was shown that administration of HTD4010 alleviated significantly the severity of biliary AP (BAP), characterized as less degree of pancreatic histological damage and acinar cell injury (both apoptosis and necroptosis), lower levels of serum amylase and pro-inflammatory cytokines. Moreover, HTD4010 down-regulated the expression of toll-like receptor 4 (TLR4) protein, and TLR4 deficiency eliminated the protective effect of HTD4010 on BAP in mice. In conclusion, these results showed that HTD4010 could alleviate the severity of pancreatitis, reduce the acinar cells necrosis and inflammatory response possibly by TLR4 signaling pathway in AP.

PAPep Inhibits Secretion of Poly(I:C)-Induced Inflammatory Cytokines and ICAM-1 Expression in Corneal Fibroblasts by Suppressing the NF-κB/p38 Pathway

PURPOSE

To assess the anti-inflammatory effect and mechanism of a novel peptide, PAPep, in poly(I:C)-stimulated corneal fibroblasts.

METHODS

Corneal fibroblasts were treated with poly(I:C) to elicit inflammation. Real-time polymerase chain reaction (PCR) and ELISA were used to measure the mRNA and protein levels of interleukin (IL)-6, monocyte chemotactic factor (MCP)-1, and interferon gamma (IFN-γ). Real-time PCR, immunofluorescence, and immunoblot were performed to determine ICAM-1 expression. Translocation of NF-κB p65 was observed by immunofluorescence. Phosphorylation of IκBα, NF-κB, and mitogen-activated protein kinase (MAPK) (p38, JNK and ERK) were detected by western blot.

RESULTS

The results showed that PAPep effectively decreased mRNA and protein expression of IL-6, MCP-1, and IFN-γ in corneal fibroblasts exposed to poly(I:C). In addition, PAPep reduced mRNA and protein levels of ICAM-1. The NF-κB and MAPK(p38) pathway were inhibited by PAPep treatment, as indicated by suppression of p65 nuclear translocation, and IκBα, NF-κB, and p38 activation. PAPep showed no effect on JNK or ERK activity.

CONCLUSIONS

PAPep attenuates the expression of inflammatory cytokines and ICAM-1 in corneal fibroblasts induced by poly(I:C) through blocking the NF-κB and MAPK(p38) pathway. PAPep may be considered a promising therapeutic agent for treating viral keratitis.

NF-κB in acute pancreatitis: Mechanisms and therapeutic potential

The incidence of acute pancreatitis (AP) is increasing globally and mortality could be high among patients with organ failure and infected necrosis. The predominant factors responsible for the morbidity and mortality of AP are systemic inflammatory response syndrome and multiorgan dysfunction. Even though preclinical studies have shown antisecretory agents (somatostatin), antioxidants (S-adenosyl methionine [SAM], selenium), protease inhibitors, platelet activating factor inhibitor (Lexipafant), and anti-inflammatory immunomodulators (eg. prostaglandin E, indomethacin) to benefit AP in terms of reducing the severity and/or mortality, most of these agents have shown heterogeneous results in clinical studies. Several years of experimental studies have implicated nuclear factor-kappa B (NF-κB) activation as an early and central event in the progression of inflammation in AP. In this manuscript, we review the literature on the role of NF-κB in the pathogenesis of AP, its early intraacinar activation, and how it results in progression of the disease. We also discuss why anti-protease, antisecretory, and anti-inflammatory agents are unlikely to be effective in clinical acute pancreatitis. NF-κB, being a central molecule that links the initial acinar injury to systemic inflammation and perpetuate the inflammation, we propose that more studies be focussed towards targeted inhibition of NF-κB activity. Direct NF-κB inhibition strategies have already been attempted in patients with various cancers. So far, peroxisome proliferator activator receptor gamma (PPAR-γ) ligand, pyrrolidine dithiocarbamate (PDTC), proteasome inhibitor and calpain I inhibitor have been shown to have direct inhibitory effects on NF-κB activation in experimental AP.

Regenerating gene (REG) product and its potential clinical usage

INTRODUCTION

The regenerating gene (Reg) was identified in regenerating islets and its related genes were revealed to constitute the Reg gene family. Reg family proteins act as growth factors for several cells. Recently, autoimmunity against the Reg family proteins has been reported in several diseases. In addition, the Reg family genes were found to be expressed in a large number of cancers and to influence prognosis.

AREAS COVERED

The historical background and current view of the structure, function, and expression of Reg family genes/proteins and their physiological/pathological significance in several diseases are described. Based on the findings, the diagnostic/therapeutic potential of Reg family genes/proteins is also discussed.

EXPERT OPINION

Autoimmunity against Reg family proteins may be a new diagnostic marker and/or therapeutic target for immune-mediated diseases. Treatment aimed at the expansion of the β-cell mass by the Reg genes/proteins, combined with the abrogation of autoimmunity, constitutes a potential approach for the treatment of diabetes. Conversely, some cancer cells have gained the ability to overexpress the Reg genes/proteins, thereby enhancing their proliferative capacities, resulting in these cells having a considerable growth advantage. Thus, the Reg genes/proteins are expected to be a new prognostic marker in cancer and/or a future therapeutic target.

Reg3α Overexpression Protects Pancreatic β Cells from Cytokine-Induced Damage and Improves Islet Transplant Outcome

The process of islet transplantation for treating type 1 diabetes has been limited by the high level of graft failure. This may be overcome by locally delivering trophic factors to enhance engraftment. Regenerating islet-derived protein 3α (Reg3α) is a pancreatic secretory protein which functions as an antimicrobial peptide in control of inflammation and cell proliferation. In this study, to investigate whether Reg3α could improve islet engraftment, a marginal mass of syngeneic islets pretransduced with adenoviruses expressing Reg3α or control EGFP were transplanted under the renal capsule of streptozotocin-induced diabetic mice. Mice receiving islets with elevated Reg3α production exhibited significantly lower blood glucose levels (9.057 ± 0.59 mmol/L versus 13.48 ± 0.35 mmol/L, P < 0.05) and improved glucose-stimulated insulin secretion (1.80 ± 0.17 ng/mL versus 1.16 ± 0.16 ng/mL, P < 0.05) compared with the control group. The decline of apoptotic events (0.57% ± 0.15% versus 1.06% ± 0.07%, P < 0.05) and increased β-cell proliferation (0.70% ± 0.10% versus 0.36% ± 0.14%, P < 0.05) were confirmed in islet grafts overexpressing Reg3α by morphometric analysis. Further experiments showed that Reg3α production dramatically protected cultured islets and pancreatic β cells from cytokine-induced apoptosis and the impairment of glucose-stimulated insulin secretion. Moreover, exposure to cytokines led to the activation of MAPKs in pancreatic β cells, which was reversed by Reg3α overexpression in contrast to control group. These results strongly suggest that Reg3α could enhance islet engraftments through its cytoprotective effect and advance the therapeutic efficacy of islet transplantation.

Protective effects and mechanisms of G5 PAMAM dendrimers against acute pancreatitis induced by caerulein in mice

In this study, generation 5 (G5) polyamidoamine (PAMAM) dendrimers with two different surface groups, G4.5-COOH and G5-OH, were investigated for their protective effects on pancreas injury in a caerulein-induced acute pancreatitis (AP) mouse model. Both dendrimers significantly decreased pathological changes in the pancreas and reduced the inflammatory infiltration of macrophages in pancreatic tissues. In addition, the expression of pro-inflammatory cytokines was significantly inhibited by the two dendrimers, not only in pancreatic tissues from AP mice but also in vitro in mouse peritoneal macrophages with LPS-induced inflammation. G4.5-COOH, which had better in vivo protective effects for AP than G5-OH, led to a significant reduction in the total number of plasma white blood cells (WBCs) and monocytes in AP mice, and its anti-inflammatory mechanism was related to inhibition of the nuclear translocation of NF-κB in macrophages.

HIP/PAP prevents excitotoxic neuronal death and promotes plasticity

Objectives

Excitotoxicity plays a significant role in the pathogenesis of perinatal brain injuries. Among the consequences of excessive activation of the N-methyl-d-aspartate (NMDA)-type glutamate are oxidative stress caused by free radical release from damaged mitochondria, neuronal death and subsequent loss of connectivity. Drugs that could protect nervous tissue and support regeneration are attractive therapeutic options. The hepatocarcinoma intestine pancreas protein/pancreatitis-associated protein I (HIP/PAP) or Reg3α, which is approved for clinical testing for the protection and regeneration of the liver, is upregulated in the central nervous system following injury or disease. Here, we examined the neuroprotective/neuroregenerative potential of HIP/PAP following excitotoxic brain injury.

Methods

We studied the expression of HIP/PAP and two of its putative effectors, cAMP-regulated phosphoprotein 19 (ARPP19) and growth-associated protein 43 (GAP-43), in the neonatal brain, and the protective/regenerative properties of HIP/PAP in three paradigms of perinatal excitotoxicity: intracerebral injection of the NMDA agonist ibotenate in newborn pups, a pediatric model of traumatic brain injury, and cultured primary cortical neurons.

Results

HIP/PAP, ARPP19, and GAP-43 were expressed in the neonatal mouse brain. HIP/PAP prevented the formation of cortical and white matter lesions and reduced neuronal death and glial activation following excitotoxic insults in vivo. In vitro, HIP/PAP promoted neuronal survival, preserved neurite complexity and fasciculation, and protected cell contents from reactive oxygen species (ROS)-induced damage.

Interpretation

HIP/PAP has strong neuroprotective/neuroregenerative potential following excitotoxic injury to the developing brain, and could represent an interesting therapeutic strategy in perinatal brain injury.

Relationship between Reg proteins and intestinal mucosa barrier damage in rats with severe acute pancreatitis

AIM: To detect the expression of regenerating islet-derived proteins (Reg)Ⅰand Ⅲ in the intestinal mucosa of rats with severe acute pancreatitis (SAP), and to evaluate the relationship between the levels of RegⅠand Ⅲ and intestinal mucosal barrier damage.

METHODS: Seventy-two adult SD rats were randomly divided into three groups: a normal control (N) group, an SAP (S) group, and a pyrrolidine dithiocarbamate (PDTC, 10 mg/kg) pretreatment (P) group. Each group was further divided into two subgroups for testing at different time points (12 and 24 h), with 12 rats in each subgroup. The rats in the S group were given 20% L-arginine (L-Arg, 2.5 g/kg) by intraperitoneal injection twice at one-hour interval to induce SAP. The N group was given equal volume of normal saline. The P group was given PDTC 10 mg/kg by intraperitoneal injection 1 h before the first injection of L-Arg. All rats were killed 12 h or 24 h after L-Arg injection to collect blood, pancreatic and intestinal tissue samples. The pathological changes in pancreatic and intestinal tissues were observed and graded under an optical microscope. ELISA was used to detect the levels of serum interleukin 22 (IL-22), tumor necrosis factor-α (TNF-α) and intestinal fatty acid binding protein (I-FABP). The expression of RegⅠand Ⅲ mRNAs in intestinal tissue was evaluated by RT-PCR. The levels of RegⅠ, Ⅲ and nuclear-factor κB (NF-κB) proteins in intestinal tissue were detected by Western blot.

RESULTS: In the SAP group, the scores of pancreatic changes (12 h: 8.92 ± 1.130; 24 h: 11.31 ± 1.609) and intestinal mucosal changes (12 h: 3.79 ± 0.689, 24 h: 4.33 ± 0.354), and the levels of IL-22 (12 h: 712.46 ng/mL ± 81.549 ng/mL, 24 h: 751.02 ng/mL ± 104.054 ng/mL), TNF-α (12 h: 138.08 ng/mL ± 20.369 ng/mL, 24 h: 159.43 ng/mL ± 24.46 ng/mL), I-FABP (12 h: 338.04 IU/mL ± 61.876 IU/mL, 24 h: 395.26 IU/mL ± 58.547 IU/mL), intestinal NF-κB p65 (12 h: 0.51 ± 0.065, 24 h: 0.60 ± 0.066), RegⅠprotein (12 h: 0.45 ± 0.047, 24 h: 0.56 ± 0.033), and Reg Ⅲ protein (12 h: 0.70 ± 0.084, 24 h: 0.92 ± 0.163) were significantly higher (P < 0.05) than those in the control group. Compared with the S group, pretreatment with different doses of PDTC significantly decreased the above parameters (P < 0.05), although the levels of these parameters were still significantly higher than those in the N group (P < 0.05). There were positive correlations among RegⅠand Ⅲ protein expression, intestinal mucosal pathological score, IL-22, I-FABP, TNF-α, and NF-κB p65 expression.

CONCLUSION: RegⅠand Ⅲ protein expression is upregulated in SAP, which is possibly associated with intestinal mucosa damage and NF-κB signaling pathway activation.

Acute pancreatitis in aging animals: Loss of pancreatitis-associated protein protection?

AIM: To investigate the effect of age on severity of acute pancreatitis (AP) using biochemical markers, histology and expression of the protective pancreatitis-associated proteins (PAPs).

METHODS: AP was induced via intraductal injection of 4% sodium taurocholate in young and old rats. Sera and pancreata were assayed at 24 h for the parameters listed above; we also employed a novel molecular technique to assess bacterial infiltration using polymerase chain reaction to measure bacterial genomic ribosomal RNA.

RESULTS: At 24 h after induction of AP, the pancreata of older animals had less edema (mean ± SE histologic score of young vs old: 3.11 ± 0.16 vs 2.50 ± -0.11, P < 0.05), decreased local inflammatory response (histologic score of stromal infiltrate: 3.11 ± 0.27 vs 2.00 ± 0.17, P < 0.05) and increased bacterial infiltration (174% ± 52% increase from sham vs 377% ± 4%, P < 0.05). A decreased expression of PAP1 and PAP2 was demonstrated by Western blotting analysis and immunohistochemical staining. There were no differences in serum amylase and lipase activity, or tissue myeloperoxidase or monocyte chemotactic protein-1 levels. However, in the most-aged group, serum C-reactive protein levels were higher (young vs old: 0.249 ± 0.04 mg/dL vs 2.45 ± 0.68 mg/dL, P < 0.05).

CONCLUSION: In older animals, there is depressed PAP expression related to a blunted inflammatory response in AP which is associated with worsened bacterial infiltration and higher C-reactive protein level; this may explain the more aggressive clinical course.

Gene expression of the endolymphatic sac

CONCLUSION

The endolymphatic sac is part of the membranous inner ear and is thought to play a role in the fluid homeostasis and immune defense of the inner ear; however, the exact function of the endolymphatic sac is not fully known. Many of the detected mRNAs in this study suggest that the endolymphatic sac has multiple and diverse functions in the inner ear.

OBJECTIVES

The objective of this study was to provide a comprehensive review of the genes expressed in the endolymphatic sac in the rat and perform a functional characterization based on measured mRNA abundance.

METHODS

Microarray technology was used to investigate the gene expression of the endolymphatic sac with the surrounding dura. Characteristic and novel endolymphatic sac genes were determined by comparing with expressions in pure dura.

RESULTS

In all, 463 genes were identified specific for the endolymphatic sac. Functional annotation clustering revealed 29 functional clusters.

Essential role of monocytes and macrophages in the progression of acute pancreatitis

Acute pancreatitis (AP) is an inflammatory condition of the pancreas caused by an imbalance in factors involved in maintaining cellular homeostasis. Earliest events in AP occur within acinar cells accompanied by other principal contributors to the inflammatory response i.e. the endothelial cells, immunocytes (granulocytes, monocytes/macrophages, lymphocytes) and neutrophils. Monocytes/macrophages are important inflammatory mediators, involved in the pathophysiology of AP, known to reside in the peritoneal cavity (in the vicinity of the pancreas) and in peripancreatic tissue. Recent studies suggested that impaired clearance of injured acini by macrophages is associated with an altered cytokine reaction which may constitute a basis for progression of AP. This review focuses on the role of monocytes/macrophages in progression of AP and discusses findings on the inflammatory process involved.

Inflammation and nerve injury induce expression of pancreatitis-associated protein-II in primary sensory neurons

Pancreatitis-associated protein (PAP)-I and -II, lectin-related secretory proteins, are members of the regenerating gene (Reg) family. Although expression of PAP-I was found in the dorsal root ganglion (DRG) neurons following peripheral nerve injury and cystitis, whether PAP-II could be expressed in DRG neurons in chronic pain models remains unclear. The present study shows an inflammation- and nerve injury-triggered expression of PAP-II in rat DRG neurons. In situ hybridization showed that only a few DRG neurons normally contained PAP-I and -II mRNAs. After peripheral inflammation, PAP-I and -II mRNAs were present in over half of small DRG neurons. Such an elevated expression of PAP-I and -II reached the peak level on the second day. Immunostaining showed that the expression of PAP-II was mostly increased in the isolectin B4-positive subset of small DRG neurons after inflammation. Furthermore, the expression of PAP-II was also induced in DRG neurons after peripheral nerve injury. Interestingly, PAP-II expression was shifted from small neurons on day 2 to large DRG neurons that expressed neuropeptide Y during the later post-injury days. These results suggest that PAP-II may play potential roles in the modulation of spinal sensory pathways in pathological pain states.

Comparison of His and GST tagged versions of recombinant pancreatitis associated protein 2 in modulation of inflammatory responses

OBJECTIVE AND DESIGN

Pancreatitis associated proteins (PAP) are highly upregulated in acute pancreatitis and other inflammatory states and have been shown to possess immunomodulatory properties. However, continued study of PAP has been hampered by the ability to effectively isolate appropriate amounts of protein from pancreatic juice or efficient generation of recombinant proteins. Here we describe two different methods for generating recombinant PAP2 protein (rPAP2), using either His or GST tagged bacterial methodology with comparison of function.

METHODS

His or GST tagged rPAP2 were generated, cultured with clonal (NR8383) macrophages and compared with respect to inflammatory cytokine expression (IL-1alpha, IL-1beta, IL-6, and TNF-alpha) and bacterial (E. coli) agglutination. Significance was determined by student's t test (P<0.05).

RESULTS

PAP2His treatment induced a 3.6, 2.8, 13.0, 3.5 fold induction of IL-1alpha, IL-1beta, TNF-alpha and IL-6, respectively; similar cytokine expression changes were observed with PAP2GST treatment (3.9, 2.6, 12.2, and 3.0 fold induction of IL-1alpha, IL-1beta, TNF-alpha and IL-6, respectively) (P<0.05). Further, incubation with recombinant PAP2 led to a time dependent increase in bacterial aggregates which was absent in controls.

CONCLUSIONS

These data demonstrate that both methods maintain functional immunomodulatory integrity for PAP2 and provide the ability to generate sufficient quantities to further study structure and function.

PAP1 signaling involves MAPK signal transduction

Pancreatitis-associated protein 1 (PAP1) belongs to the Reg family of secretory proteins. Several important biological roles have been attributed to PAP1 but the signaling pathways activated by this protein remain only partially understood. Here, we describe the intracellular pathways triggered by PAP1 in a pancreatic acinar cell line. Taking advantage of the fact that PAP1 induces its own transcription, we performed ChIP assays to analyze the recruitment of transcriptional factors on its promoter. Our results show that PAP1 increased the transactivation activity of pap1 and the binding on its promoter of the nuclear factors C/EBPbeta, P-CREB, P-ELK1, EGR1, STAT3, and ETS2, which are downstream targets of MAPK signaling. p44/42, p38, and JNK MAPKs activity increased after PAP1 treatment. In addition, pharmacological inhibition of these kinases markedly inhibited the induction of pap1 mRNA. Taken together, these results indicated that the mechanism of PAP1 action involves the activation of the MAPK superfamily.

Mutational characterization of pancreatitis-associated protein 2 domains involved in mediating cytokine secretion in macrophages and the NF-kappaB pathway

Pancreatitis-associated protein 2 (PAP2) is a member of the Reg3 gene family and is classified as a group 7 C-type lectin-like protein. In rats, each of the three PAP isoforms has independent immunologic functional effects on macrophages. We have previously shown that PAP2 up-regulates inflammatory cytokines in macrophages in a dose-dependent manner and acts through NF-kappaB mechanisms. In this study, we aimed to determine protein domains that are essential for the immunologic function of PAP2 by mutational or chemical analysis. The protein activity for each mutant was determined by measuring TNF-alpha, IL-6, or IL-1 production in macrophages. Truncation of the first 25 residues on the N terminus of PAP2 did not affect protein activity whereas truncation of the last 30 residues of the C terminus of PAP2 completely inactivated the function of PAP2. Additionally, reduction of three disulfide bonds proved to be important for the activity of this protein. Further investigation revealed two invariant disulfide bonds were important for activity of PAP2 while the disulfide bond that is observed in long-form C-type lectin proteins was not essential for activity. Coupling the ability of PAP2 to up-regulate inflammatory cytokines via NF-kappaB with its associated expression in acute pancreatitis, a condition with aberrant concentrations of inflammatory cytokines, we investigated whether PAP2 mutants mechanistically activate the NF-kappaB-signaling pathway and demonstrate that preincubation with select rPAP2 mutant proteins affect translocation of this transcription factor into the nucleus.