Coordinate regulation of PSP/reg and PAP isoforms as a family of secretory stress proteins in an animal model of chronic pancreatitis

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.

Diagnostic accuracy of pancreatic stone protein in patients with sepsis: a systematic review and meta-analysis

BACKGROUND

Sepsis is a common syndrome of multiorgan system dysfunction secondary to the dysregulated inflammatory response to infection. The role of pancreatic stone protein (PSP) in diagnosing sepsis has been investigated in previous studies. The meta-analysis aimed to comprehensively investigate the diagnostic value of PSP in identifying sepsis.

METHODS

PubMed, Web of Science, Embase, Cochrane Library, and China National Knowledge Infrastructure (CNKI), were systematically searched. Studies investigating the diagnostic performance of PSP were included. Pooled sensitivity, specificity, positive Likelihood Ratio (+ LR) and negative Likelihood Ratio (-LR), diagnostic odds ratio (DOR), and area under the curve (AUC) of summary receiver operating characteristic (SROC) were calculated.

RESULTS

The sensitivity of PSP was 0.88 (95% CI: 0.77-0.94), and the pooled specificity was 0.78 (95% CI: 0.65-0.87). Pooled + LR, -LR, and DOR were 4.1 (2.3, 7.3), 0.16 (0.07, 0.34), and 26 (7, 98). The AUC value for the SROC of PSP was 0.90 (0.87, 0.92). The pooled sensitivity, specificity, + LR and - LR, and DOR for PSP among neonates were 0.91 (95% CI: 0.84, 0.96), 0.66 (95% CI: 0.58, 0.74), 3.97 (95% CI: 0.53, 29.58), 0.13 (95% CI: 0.02, 1.00), and 31.27 (95% CI: 0.97, 1004.60).

CONCLUSIONS

This study indicates that PSP demonstrated favorable diagnostic accuracy in detecting sepsis. Well-designed studies are warranted to ascertain the value of PSP measurement to guide early empirical antibiotic treatment, particularly in neonates.

Identification of regenerating island-derived protein 3E in dogs

Regenerating islet-derived protein (REG) 1A (aka pancreatic stone protein) and REG3A (aka pancreatitis-associated protein) are upregulated in humans with sepsis, pancreatitis, and gastrointestinal diseases, but little is known about this protein family in dogs. Our aim was to identify REG1 and REG3 family members in dogs. REG-family genes were computationally annotated in the canine genome and proteome, with verification of gene expression using publicly available RNA-seq data. The presence of the protein in canine pancreatic tissue and plasma was investigated with Western blot and immunohistochemistry, using anti-human REG1A and REG3A antibodies. Protein identity was confirmed with mass spectrometry. Two members of the REG3 subfamily were found in the canine genome, REG3E1 and REG3E2, both encoding for the same 176 AA protein, subsequently named REG3E. Anti-human REG3A antibodies demonstrated cross-reactivity with the canine REG3E protein in pancreas homogenates. In canine plasma, a protein band of approximately 17 kDa was apparent. Mass spectrometry confirmed this protein to be the product of the two annotated REG3E genes. Strong immunoreactivity to anti-human REG3A antibodies was found in sections of canine pancreas affected with acute pancreatitis, but it was weak in healthy pancreatic tissue. Recombinant canine REG3E protein underwent a selective trypsin digestion as described in other species. No evidence for the presence of a homolog of REG1A in dogs was found in any of the investigations. In conclusion, dogs express REG3E in the pancreas, whose role as biomarker merits further investigations. Homologs to human REG1A are not likely to exist in dogs.

Incidence and Time Point of Sepsis Detection as Related to Different Sepsis Definitions in Severely Burned Patients and Their Accompanying Time Course of Pro-Inflammatory Biomarkers

Background: Diagnosis of sepsis in burn patients remains difficult for various reasons. One major problem is the definition of sepsis itself. Therefore, previous and current sepsis definitions are a matter of ongoing validation, but a well-defined consensus on which clinical and laboratory parameters to incorporate in such a definition is lacking. The aim of the present study was to compare the incidence and time-related occurrence of septic events according to different definitions as well as their accompanying time course of pro-inflammatory biomarkers. Methods: Across the first 14 days after admission, the incidence and time point of sepsis according to three different definitions (Sepsis-3, Sepsis American Burns Association [ABA] 2007, Sepsis Zurich Burn Center) were assessed on a daily basis in adult burn patients with total body surface area (TBSA) ≥15% admitted to the Zurich Burn Center between May 2015 and October 2018. In order to investigate how well daily drawn proinflammatory biomarkers (white blood cells (WBCs), C-reactive protein (CRP), procalcitonin (PCT), and novel pancreatic stone protein (PSP)) reflect the progression of sepsis depending on its type of definition, a longitudinal mixed model analysis was performed across the first 14 days for septic and non-septic patients. Additionally, the relative increase of biomarker levels 24, 48, and 72 h prior to a septic event was analyzed for each definition used. Results: In our cohort of 90 severely burned patients, Sepsis-3 identified 46 patients (51.1%) as septic, while ABA 2007 and the Zurich Burn Center definition counted 33 patients (36.7%) and 24 patients (26.6%), respectively. Sepsis-3 detected sepsis about 1 day earlier than Sepsis ABA 2007 (p < 0.001) and about 0.5 days earlier than Sepsis Zurich Burn Center (p = 0.04). The course of pro-inflammatory biomarkers was largely unaffected by the type of sepsis definition. Irrespective of the sepsis definition, PSP was the only marker to demonstrate a highly significant interaction between time and group (sepsis versus no sepsis) (p < 0.001) with a 3.3–5.5-fold increase within 72 h before the event of sepsis, whereas CRP, PCT, and WBC showed only mild undulations. Conclusions: Despite the ongoing dilemma of how to define sepsis in burn patients, a continually calculated SOFA score as used in Sepsis-3 is advantageous to early identify a patient’s detrimental progression to sepsis. Inclusion of biomarkers, such as PSP, may help support the burn specialist’s diagnosis of sepsis and could improve the diagnostic performance of current and future definitions in burn patients.

Response of routine inflammatory biomarkers and novel Pancreatic Stone Protein to inhalation injury and its interference with sepsis detection in severely burned patients

BACKGROUND

Inhalation of thermal and chemical products of combustion evokes an immune response measurable at a systemic level. Inhalation injury related kinetics of currently available inflammatory biomarkers and novel Pancreatic Stone Protein (PSP) as well as their interference with septic events has not been addressed to literature yet.

METHODS

Analysis of the influence of inhalation injury and ARDS on biomarker kinetics (PSP, procalcitonin (PCT), C-reactive Protein (CRP), white blood cells (WBC)) in 90 patients admitted to Zurich Burn Center between May 2015 and October 2018 with burns ≥15% total body surface area (TBSA) over 14 days.

RESULTS

Twenty-five (27%) of 90 included patients presented with inhalation injury (median age 52 years [IQR 27], median TBSA 31.5% [IQR 21], mean ABSI-Score 7±3). At admission, only WBC demonstrated significantly higher values in the inhalation injury group (p=0.011). Acute respiratory distress syndrome (ARDS) was present in 32% without association to the severity of inhalation injury (p=0.11). WBC, CRP and PCT failed to delineate inhalation injury related inflammation from septic progression at most time points. PSP was the strongest marker to identify septic patients both by its higher values and steeper increase over time (p<0.001).

CONCLUSION

Inhalation injury leads to an inflammatory response at a systemic level with alterations of biomarkers. While routine inflammatory markers demonstrated strong interferences between inhalation injury with its associated ARDS and evolving sepsis, PSP reliably identified septic patients in a setting of inflammatory turbulences secondary to inhalation injury.

Pancreatic Stone Protein Predicts Sepsis in Severely Burned Patients Irrespective of Trauma Severity: A Monocentric Observational Study

OBJECTIVE

The burn victim's inherent state of hyperinflammation frequently camouflages septic events delaying the initiation of targeted intensive care therapy. Accurate biomarkers are urgently needed to support sepsis detection before patients' clinical deterioration.

SUMMARY OF BACKGROUND DATA

Evidence on the usefulness of pancreatic stone protein (PSP) as a powerful diagnostic and prognostic marker in critically ill patients has recently accumulated.

METHODS

Analysis of biomarker kinetics (PSP, routine markers) was performed on 90 patients admitted to the Zurich Burn Center between May 2015 and October 2018 with burns ≥15% total body surface area with regard to infection and sepsis (Sepsis-3) over a 14-day time course.

RESULTS

PSP differentiated between sepsis, infection and sterile inflammation from day 3 onward with an area under the curve of up to 0.89 (P < 0.001), therefore, competing with procalcitonin (area under the curve = 0.86, P < 0.001). Compared to routine inflammatory biomarkers, only PSP demonstrated a significant interaction between time and presence of sepsis - signifying a steeper increase in PSP levels in septic patients as opposed to those exhibiting a nonseptic course (interaction P < 0.001). Event-related analysis demonstrated tripled PSP serum levels within 72 hours and doubled levels within 48 hours before a clinically apparent sepsis.

CONCLUSION

PSP is able to differentiate between septic and nonseptic patients during acute burn care. Its steep rise up to 72 hours before clinically overt deterioration has the potential for physicians to timely initiate treatment with reduced mortality and costs.

MicroRNA-7 directly targets Reg1 in pancreatic cells

Regenerating islet-derived (Reg) proteins, which were first discovered in the pancreas, are associated with increased proliferation, prevention of apoptosis, and enhanced differentiation in normal and disease states, but very little is known about the regulation of their expression. We hypothesized that Reg expression is influenced by microRNAs. Bioinformatic analysis predicted Reg1 to be a target of microRNA-7 (miR-7), which influences pancreatic β-cell function. To this end, we investigated the effects of miR-7 on Reg1 expression in pancreatic acinar and islet β-cells. High levels of Reg1 were noted by immunostaining and Western blotting in acinar cells in contrast to islet cells. A reciprocal expression pattern was observed for miR-7. Overexpression of miR-7 resulted in Reg1 mRNA suppression and reduction of secreted Reg1 protein. Conversely, miR-7 knockdown led to increases in Reg1. Targeting of Reg1 by miR-7 was confirmed via luciferase activity assays. In contrast, miR-7 did not directly repress the human ortholog of Reg1 REG1A as well as REG1B indicating species differences in the regulation of Reg expression. This is the first account of microRNA modulation of any Reg member warranting studies to fill gaps in our knowledge of Reg protein biology, particularly in disease contexts.

The role of keratins in the digestive system: lessons from transgenic mouse models

Keratins are the largest subfamily of intermediate filament proteins. They are either type I acidic or type II basic keratins. Keratins form obligate heteropolymer in epithelial cells and their expression patterns are tissue-specific. Studies have shown that keratin mutations are the cause of many diseases in humans or predispose humans to acquiring them. Using mouse models to study keratin-associated human diseases is critical, because they allow researchers to get a better understanding of these diseases and their progressions, and so many such studies have been conducted. Acknowledging the importance, researches with genetically modified mice expressing human disease-associated keratin mutants have been widely done. Numerous studies using keratin knockout mice, keratin-overexpressed mice, or transgenic mice expressing keratin mutants have been conducted. This review summarizes the mouse models that have been used to study type I and type II keratin expression in the digestive organs, namely, the liver, pancreas, and colon.

Pancreatic stone protein (PSP) and pancreatitis-associated protein (PAP): a protocol of a cohort study on the diagnostic efficacy and prognostic value of PSP and PAP as postoperative markers of septic complications in patients undergoing abdominal surgery (PSP study)

INTRODUCTION

Major abdominal surgery leads to a postoperative systemic inflammatory response, making it difficult to discriminate patients with systemic inflammatory response syndrome from those with a beginning postoperative infectious complication. At present, physicians have to rely on their clinical experience to differentiate between the two. Pancreatic stone protein (PSP) and pancreatitis-associated protein (PAP), both secretory proteins produced by the pancreas, are dramatically increased during pancreatic disease and have been shown to act as acute-phase proteins. Increased levels of PSP have been detected in polytrauma patients developing sepsis and PSP has shown a high diagnostic accuracy in discriminating the severity of peritonitis and in predicting death in intensive care unit patients. However, the prognostic value of PSP/PAP for infectious complications among patients undergoing major abdominal surgery is unknown.

METHODS AND ANALYSIS

160 patients undergoing major abdominal surgery will be recruited preoperatively. On the day before surgery, baseline blood values are attained. Following surgery, daily blood samples for measuring regular inflammatory markers (c-reactive protein, procalcitonin, interleukin-6, tumour necrosis factor-α and leucocyte counts) and PSP/PAP will be acquired. PSP/PAP will be measured using a validated ELISA developed in our research laboratory. Patient's discharge marks the end of his/her trial participation. Complication grade including mortality and occurrence of infectious postoperative complications according to validated diagnostic criteria will be correlated with PSP/PAP values. Total intensive care unit days and total length of stay will be recorded as further outcome parameters.

ETHICS AND DISSEMINATION

The PSP trial is a prospective monocentric cohort study evaluating the prognostic value of PSP and PAP for postoperative infectious complications. In addition, a comparison with established inflammatory markers in patients undergoing major abdominal surgery will be performed to help evaluate the role of these proteins in predicting and diagnosing infectious and other postoperative complications.

INSTITUTION ETHICS BOARD APPROVAL ID

KEKZH-Nr. STV 11-2009.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01258179.

Regenerating 1 and 3b gene expression in the pancreas of type 2 diabetic Goto-Kakizaki (GK) rats

Regenerating (REG) proteins are associated with islet development, β-cell damage, diabetes and pancreatitis. Particularly, REG-1 and REG-3-beta are involved in cell growth/survival and/or inflammation and the Reg1 promoter contains interleukin-6 (IL-6)-responsive elements. We showed by transcriptome analysis that islets of Goto-Kakizaki (GK) rats, a model of spontaneous type 2 diabetes, overexpress Reg1, 3α, 3β and 3γ, vs Wistar islets. Goto-Kakizaki rat islets also exhibit increased cytokine/chemokine expression/release, particularly IL-6. Here we analyzed Reg1 and Reg3β expression and REG-1 immuno-localization in the GK rat pancreas in relationship with inflammation. Isolated pancreatic islets and acinar tissue from male adult Wistar and diabetic GK rats were used for quantitative RT-PCR analysis. REG-1 immunohistochemistry was performed on paraffin sections with a monoclonal anti-rat REG-1 antibody. Islet cytokine/chemokine release was measured after 48 h-culture. Islet macrophage-positive area was quantified on cryostat sections using anti-CD68 and major histocompatibility complex (MHC) class II antibodies. Pancreatic exocrine-to-endocrine Reg1 and Reg3β mRNA ratios were markedly increased in Wistar vs GK rats. Conversely, both genes were upregulated in isolated GK rat islets. These findings were unexpected, because Reg genes are expressed in the pancreatic acinar tissue. However, we observed REG-1 protein labeling in acinar peri-ductal tissue close to islets and around large, often disorganized, GK rat islets, which may retain acinar cells due to their irregular shape. These large islets also showed peri-islet macrophage infiltration and increased release of various cytokines/chemokines, particularly IL-6. Thus, IL-6 might potentially trigger acinar REG-1 expression and secretion in the vicinity of large diabetic GK rat islets. This increased acinar REG-1 expression might reflect an adaptive though unsuccessful response to deleterious microenvironment.

Pancreatic stone protein predicts positive sputum bacteriology in exacerbations of COPD

BACKGROUND

Pancreatic stone protein/regenerating protein (PSP/reg) serum levels are supposed to be increased in bacterial inflammation. PSP/reg levels also might be useful, therefore, as a predictor of bacterial infection in COPD.

METHODS

Two hundred consecutive patients presenting to the ED due to acute exacerbation of COPD were prospectively assessed. Patients were evaluated based on clinical, laboratory, and lung functional parameters at admission (exacerbation) and after short-term follow-up (14-21 days). PSP/reg serum values were measured by a newly developed enzyme-linked immunosorbent assay.

RESULTS

PSP/reg levels were elevated in subjects with COPD exacerbation (23.8 ng/mL; 95% CI, 17.1-32.7) when compared with those with stable disease (19.1 ng/mL; 95% CI, 14.1-30.4; P 5 .03) and healthy control subjects (14.0 ng/mL; 95% CI , 12.0-19.0; P , .01). Higher PSP/reg values were observed in exacerbations with positive sputum bacteriology compared with those with negative sputum bacteriology (26.1 ng/mL [95% CI, 19.2-38.1] vs 20.8 ng/mL [95% CI , 15.6-27.2]; P , .01). Multivariate regression analysis revealed PSP/reg level as an independent predictor of positive sputum bacteriology. A combination of a PSP/reg cutoff value of . 33.9 ng/mL and presence of discolored sputum had a specificity of 97% to identify patients with pathogenic bacteria on sputum culture. In contrast, PSP/reg levels , 18.4 ng/mL and nonpurulent sputum ruled out positive bacterial sputum culture (sensitivity, 92%). In survival analysis, high PSP/reg levels at hospital admission were associated with increased 2-year mortality.

CONCLUSIONS

Serum PSP/reg level might represent a promising new biomarker to identify bacterial etiology of COPD exacerbation.

Regenerating proteins and their expression, regulation and signaling

The regenerating (Reg) protein family comprises C-type lectin-like proteins discovered independently during pancreatitis and pancreatic islet regeneration. However, an increasing number of studies provide evidence of participation of Reg proteins in the proliferation and differentiation of diverse cell types. Moreover, Reg family members are associated with various pathologies, including diabetes and forms of gastrointestinal cancer. These findings have led to the emergence of key roles for Reg proteins as anti-inflammatory, antiapoptotic and mitogenic agents in multiple physiologic and disease contexts. Yet, there are significant gaps in our knowledge regarding the regulation of expression of different Reg genes. In addition, the pathways relaying Reg-triggered signals, their targets and potential cross-talk with other cascades are still largely unknown. In this review, the expression patterns of different Reg members in the pancreas and extrapancreatic tissues are described. Moreover, factors known to modulate Reg levels in different cell types are discussed. Several signaling pathways, which have been implicated in conferring the effects of Reg ligands to date, are also delineated. Further efforts are necessary for elucidating the biological processes underlying the action of Reg proteins and their involvement in various maladies. Better understanding of the function of Reg genes and proteins will be beneficial in the design and development of therapies utilizing or targeting this protein group.

Pancreatic stone protein: a marker of organ failure and outcome in ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) is the most common hospital-acquired, life-threatening infection. Poor outcome and health-care costs of nosocomial pneumonia remain a global burden. Currently, physicians rely on their experience to discriminate patients with good and poor outcome. However, standardized prognostic measures might guide medical decisions in the future. Pancreatic stone protein (PSP)/regenerating protein (reg) is associated with inflammation, infection, and other disease-related stimuli. The prognostic value of PSP/reg among critically ill patients is unknown. The aim of this pilot study was to evaluate PSP/reg in VAP.

METHODS

One hundred one patients with clinically diagnosed VAP were assessed. PSP/reg was retrospectively analyzed using deep-frozen serum samples from VAP onset up to day 7. The main end point was death within 28 days after VAP onset.

RESULTS

Serum PSP/reg was associated with the sequential organ failure assessment score from VAP onset (Spearman rank correlation coefficient 0.49 P < .001) up to day 7. PSP/reg levels at VAP onset were elevated in nonsurvivors (n = 20) as compared with survivors (117.0 ng/mL [36.1-295.3] vs 36.3 ng/mL [21.0-124.0] P = .011). The areas under the receiver operating characteristic curves of PSP/reg to predict mortality/survival were 0.69 at VAP onset and 0.76 at day 7. Two PSP/reg cutoffs potentially allow for identification of individuals with a particularly good and poor outcome. Whereas PSP/reg levels below 24 ng/mL at VAP onset were associated with a good chance of survival, levels above 177 ng/mL at day 7 were present in patients with a very poor outcome.

CONCLUSIONS

Serum PSP/reg is a biomarker related to organ failure and outcome in patients with VAP.

TRIAL REGISTRY

ISRCTN.org; No.: ISRCTN61015974; URL: www.isrctn.org.

Coordinated age-dependent and pancreatic-specific expression of mouse Reg2Reg3α, and Reg3β genes

Reg family proteins such as Reg1 and islet neogenesis-associated protein (INGAP) have long been implicated in the growth and/or neogenesis of pancreatic islet cells. Recent reports further suggest similar roles to be played by new members such as Reg2, Reg3α, and Reg3β. We have studied their age-, isoform-, and tissue-specific expressions. RNA and protein were isolated from C57BL/6 mice aged 7, 30, and 90 days. Using real-time polymerase chain reaction, the levels of Reg gene expression in the pancreas were 20-600-fold higher than that in other tissues (≫duodenum>stomach>liver); gene expression of Reg2, Reg3α, and Reg3β was age dependent as it was hardly detectable at day 7, increased drastically at day 30, and significantly decreased at day 90; the levels of pancreatic proteins displayed similar age-dependent variations. Using dual-labeled immunofluorescence, Reg2, Reg3α, and Reg3β were abundantly expressed in most acinar cells of the pancreas, in contrast to INGAP which exhibited stepwise increases from day 7 to day 90 and colocalized with the α-cells. These new Reg genes were mainly expressed in the pancreas, with clear age-dependent and isoform-specific patterns.

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.

Inflammation-dependent expression of SPARC during development of chronic pancreatitis in WBN/Kob rats and a microarray gene expression analysis

The pathophysiology of human chronic pancreatitis is not well understood and difficult to follow on a molecular basis. Therefore, we used a rat model [Wistar-Bonn/Kobori (WBN/Kob)] that exhibits spontaneous chronic inflammation and fibrosis in the pancreas. Using microarrays we compared gene expression patterns in the pancreas during development of inflammation and fibrosis of WBN/Kob rats with age-matched healthy Wistar rats. The extracellular matrix protein SPARC (secreted protein, acidic, and rich in cysteines) and other transcripts of inflammatory genes were quantified by real-time PCR, and some were localized by immunohistochemistry. When pancreatic inflammation becomes obvious at the age of 16 wk, several hundred genes are increased between 3- and 50-fold in WBN/Kob rats compared with healthy Wistar rats. Proteins produced by acinar cells and characteristic for inflammation, e.g., pancreatitis-associated protein, are highly upregulated. Other proteins, derived from infiltrating inflammatory cells and from activated stellate cells (fibrosis) such as collagens and fibronectins are also significantly upregulated. SPARC was localized to acinar cells where it increased in the vicinity of inflammatory foci. However, acinar expression of SPARC was lost during destruction of acinar cells. In human pancreatic specimens with chronic pancreatitis, SPARC exhibited a similar expression profile. During chronic inflammation and fibrosis in the WBN/Kob rat, inflammatory genes, growth factors, and structural genes exhibit a high increase of expression. A temporal profile including pre- and postinflammatory phases indicates a concurrent activation of inflammatory and fibrotic changes. Inflammation dependent expression of SPARC appears to be lost during acinar-to-duct metaplasia both in rat and human pancreas.

Ellagic acid inhibits pancreatic fibrosis in male Wistar Bonn/Kobori rats

The key pathological features of chronic pancreatitis are chronic inflammation, acinar atrophy, and pancreatic fibrosis. We have previously shown that ellagic acid, a plant-derived polyphenol found in fruits and nuts, inhibited activation of pancreatic stellate cells, a major profibrogenic cell type in the pancreas, in vitro. Here we examined whether ellagic acid inhibited the development of pancreatic fibrosis in vivo. Ellagic acid was administered orally in the diet to ten-week-old male Wistar Bonn/Kobori rats, an experimental model of spontaneous chronic pancreatitis, for ten weeks. Ellagic acid (100 mg/kg body weight/day) attenuated pancreatic inflammation and fibrosis. The protective effects were confirmed by an increase in pancreatic weight and decreases in myeloperoxidase activity (an index of neutrophil infiltration), collagen content, transforming growth factor-beta1 expression, and the number of alpha-smooth muscle actin-positive cells (activated pancreatic stellate cells) and ED-1-positive cells (macrophages/monocytes). Ellagic acid inhibited the production of reactive oxygen species in pancreatic stellate cells in response to transforming growth factor-beta1 or platelet-derived growth factor. Our results suggest that ellagic acid might be a candidate for treatment of chronic pancreatitis.

Pancreatitis-associated protein inhibits human pancreatic stellate cell MMP-1 and -2, TIMP-1 and -2 secretion and RECK expression

BACKGROUND/AIMS

Pancreatic stellate cells (PSCs) play a key role in fibrogenesis associated with acute and chronic pancreatitis. Pancreatitis-associated protein (PAP), an acute-phase protein, is dramatically upregulated during acute and chronic pancreatitis. Assuming a protective role of PAP, we investigated its effects on human PSCs.

METHODS

PSCs were obtained by outgrowth from fibrotic human pancreas tissue. PAP was expressed in the yeast Pichia pastoris. PAP was added at 10 ng/ml to cultured PSCs. Cell proliferation was determined by bromodeoxyuridine incorporation. PSC migration was assessed by a wound healing assay. Collagen types I and III, fibronectin, matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs) and reversion-inducing cysteine-rich protein with Kazal motifs (RECK) were demonstrated on protein and mRNA level.

RESULTS

PAP had no significant effect on PSC proliferation and migration. Cell-associated fibrillar collagen types I and III and fibronectin increased after addition of PAP to PSCs. PAP diminished the expression of MMP-1 and -2 and TIMP-1 and -2 and their concentrations in PSC supernatants. RECK was detected on the surface of PSCs and its expression was reduced after PAP application.

CONCLUSIONS

Our data offer new insights into the biological functions of PAP, which may play an important role in wound healing response and cell-matrix interactions.

Pancreatitis-associated protein 2 modulates inflammatory responses in macrophages

Pancreatitis-associated proteins (PAP) are stress-induced secretory proteins that are implicated in immunoregulation. Previous studies have demonstrated that PAP is up-regulated in acute pancreatitis and that gene knockdown of PAP correlated with worsening severity of pancreatitis, suggesting a protective effect for PAP. In the present study, we investigated the effect of PAP2 in the regulation of macrophage physiology. rPAP2 administration to clonal (NR8383) and primary macrophages were followed by an assessment of cell morphology, inflammatory cytokine expression, and studies of cell-signaling pathways. NR8383 macrophages which were cultured in the presence of PAP2 aggregated and exhibited increased expression of IL-1, IL-6, TNF-alpha, and IL-10; no significant change was observed in IL-12, IL-15, and IL-18 when compared with controls. Chemical inhibition of the NFkappaB pathway abolished cytokine production and PAP facilitated nuclear translocation of NF-kappaB and phosphorylation of IkappaB alpha inhibitory protein suggesting that PAP2 signaling involves this pathway. Cytokine responses were dose dependent. Interestingly, similar findings were observed with primary macrophages derived from lung, peritoneum, and blood but not spleen. Furthermore, PAP2 activity was inhibited by the presence of serum, inhibition which was overcome with increased PAP2. Our results demonstrate a new function for PAP2: it stimulates macrophage activity and likely modulates the inflammatory environment of pancreatitis.

Reg genes are CCK2 receptor targets in ElasCCK2 mice pancreas

We previously demonstrated that expression of the gastrin receptor, CCK2R, in pancreatic acini of transgenic ElasCCK2 mice induced alteration of acinar morphology and differentiation, increased sensitivity to a carcinogen and development of preneoplastic lesions and tumours. Reg proteins are suggested to be involved in pancreatic cancer and in regeneration of endocrine pancreas. Reg I gene is a known target of gastrin. We examined whether an expression of CCK2R in the pancreatic acini of ElasCCK2 mice is linked to induction of Reg proteins expression. We analyzed Reg expression by Western-blot and immunohistochemistry in pancreas from ElasCCK2 and control mice. Islet neogenesis, glucose homeostasis, insulin secretion and content were also evaluated. Reg I is exclusively produced in acini in ElasCCK2 and control mice. In tumoral pancreas, Reg I and Reg III proteins are expressed in duct-like cells in preneoplastic lesions or in the periphery of tumours and in adjacent acini. The expression of Reg III proteins is increased in ElasCCK2 pancreas before the development of preneoplastic lesions in a subpopulation of islet cells and in small islet-like cell clusters dispersed within the acinar tissue. Several criteria of an enhanced neogenesis are fulfilled in ElasCCK2 pancreas. Moreover, ElasCCK2 mice have an improved response to glucose load, an increased insulin secretion and a doubling of insulin content compared to control mice. We show that Reg proteins are targets of CCK2R activation and are induced during early steps of carcinogenesis in ElasCCK2 mice pancreas. Alterations of exocrine tissue homeostasis in ElasCCK2 pancreas concomitantly activate regenerative responses of the endocrine pancreas possibly linked to paracrine actions of Reg III proteins.

Prostaglandin E2 modulates TNF-alpha-induced MCP-1 synthesis in pancreatic acinar cells in a PKA-dependent manner

Cyclooxygenase (COX)-2 is increased in human chronic pancreatitis. We recently demonstrated in a model of chronic pancreatitis (WBN/Kob rat) that inhibition of COX-2 activity reduces and delays pancreatic inflammation and fibrosis. Monocyte chemoattractant protein (MCP)-1 mRNA and PGE(2) were significantly reduced, correlating with a decreased infiltration of macrophages. MCP-1 plays an important role in the recruitment of macrophages to the site of tissue injury. The aim of our study is to identify mechanisms by which macrophages and acinar cells maintain an inflammatory reaction. The expression profile of E prostanoid receptors EP(1-4) and MCP-1 was analyzed by RT-PCR from pancreatic specimens and AR42J cells. MCP-1 secretion was detected by ELISA from rat pancreatic lobuli. We determined EP(1-4) mRNA levels in WBN/Kob rats with chronic pancreatic inflammation. Individual isoforms were highly increased in rat pancreas, concurrent with MCP-1 mRNA expression. In supernatants of pancreatic lobuli and AR42J cells, MCP-1 was detectable by ELISA. In the presence of TNF-alpha, MCP-1 was upregulated. Coincubation with PGE(2) enhanced the TNF-alpha-induced MCP-1 synthesis significantly. Similarly, TNF-alpha mRNA was synergistically upregulated by TNF-alpha and PGE(2). Furthermore, the synergistic effect of TNF-alpha and PGE(2) was abolished by inhibition of PKA but not of PKC. We conclude that EP receptors are upregulated during chronic pancreatic inflammation. PGE(2) modulates the TNF-alpha-induced MCP-1 synthesis and secretion from acinar cells. This synergistic effect is controlled by PKA. This mechanism might explain the COX-2-dependent propagation of pancreatic inflammation.

Reg-II is an exocrine pancreas injury-response product that is up-regulated by keratin absence or mutation

The major keratins in the pancreas and liver are keratins 8 and 18 (K8/K18), but their function seemingly differs in that liver K8/K18 are essential cytoprotective proteins, whereas pancreatic K8/K18 are dispensable. This functional dichotomy raises the hypothesis that K8-null pancreata may undergo compensatory cytoprotective gene expression. We tested this hypothesis by comparing the gene expression profile in pancreata of wild-type and K8-null mice. Most prominent among the up-regulated genes in K8-null pancreas was mRNA for regenerating islet-derived (Reg)-II, which was confirmed by quantitative reverse transcription-polymerase chain reaction and by an anti-Reg-II peptide antibody we generated. Both K8-null and wild-type mice express Reg-II predominantly in acinar cells as determined by in situ hybridization and immunostaining. Analysis of Reg-II expression in various keratin-related transgenic mouse models showed that its induction also occurs in response to keratin cytoplasmic filament collapse, absence, or ablation of K18 Ser52 but not Ser33 phosphorylation via Ser-to-Ala mutation, which represent situations associated with predisposition to liver but not pancreatic injury. In wild-type mice, Reg-II is markedly up-regulated in two established pancreatitis models in response to injury and during the recovery phase. Thus, Reg-II is a likely mouse exocrine pancreas cytoprotective candidate protein whose expression is regulated by keratin filament organization and phosphorylation.

Exocrine Meets Endocrine: Pancreatic Stone Protein and Regenerating Protein—Two Sides of the Same Coin

BACKGROUND

Regenerating protein (reg) and pancreatic stone protein (PSP) have been discovered independently in the fields of diabetes and pancreatitis.

MATERIALS AND METHODS

These proteins are identical; however, because of the gap between the endocrine and exocrine field, there was never a consensus and the nomenclature has not been rectified. Since the time of the initial discovery, more isoforms have been unified. Historically, PSP was discovered long before reg, yet, in many areas outside of the pancreatitis research field, reg is being used.

RESULTS

For PSP/reg, a role in proliferation and regeneration of islet cells has been postulated. A hitherto insufficiently understood phenomenon is the massive up-regulation of PSP/reg in pancreatic tissue and juice under conditions of stress. Similarly, PAP (pancreatitis-associated protein)/reg III has been attributed various functional roles. Structurally, the ability to form fibrils after tryptic cleavage is a striking common features of both proteins. However, this biochemical transformation is in itself not enough to gain functional insight. Thus, physiological and genetic approaches are required to further characterize the role of these proteins in the pancreas. Recently, more evidence has been presented in support of the theory that PSP/reg plays a key role in islet neogenesis/regeneration.

CONCLUSIONS

In this review we discuss the debate on the localization and functional roles of PSP/reg and PAP/regIII. Therefore, we have summarized hypotheses and experimental results supporting such hypotheses.

Caerulein-induced acute pancreatitis in mice that constitutively overexpress Reg/PAP genes

BACKGROUND

The cystic fibrosis (CF) mouse pancreas has constitutively elevated expression of the Reg/PAP cell stress genes (60-fold greater Reg3alpha, and 10-fold greater PAP/Reg3beta and Reg3gamma). These genes are suggested to be involved in protection or recovery from pancreatic injury.

METHODS

To test this idea the supramaximal caerulein model was used to induce acute pancreatitis in wild type and CF mice. Serum amylase, pancreatic water content (as a measure of edema), pancreatic myeloperoxidase activity, and Reg/PAP expression were quantified.

RESULTS

In both wild type and CF mice caerulein induced similar elevations in serum amylase (maximal at 12 h), pancreatic edema (maximal at 7 h), and pancreatic myeloperoxidase activity (MPO, a marker of neutrophil infiltration; maximal at 7 h). By immunohistochemistry, Reg3alpha was strongly expressed in the untreated CF pancreas but not in wild type. During pancreatitis, Reg3alpha was intensely expressed in foci of inflamed tissue in both wild type and CF.

CONCLUSION

These data demonstrate that the severity of caerulein-induced pancreatitis is not ameliorated in the CF mouse even though the Reg/PAP stress genes are already highly upregulated. While Reg/PAP may be protective they may also have a negative effect during pancreatitis due to their anti-apoptotic activity, which has been shown to increase the severity of pancreatitis.

Pancreatitis-associated protein I suppresses NF-kappa B activation through a JAK/STAT-mediated mechanism in epithelial cells

Pancreatitis-associated protein I (PAP I), also known as HIP, p23, or Reg2 protein, has recently been implicated in the endogenous regulation of inflammation. Although it was initially characterized as a protein that is overexpressed in acute pancreatitis, PAP I has also been associated with a number of inflammatory diseases, such as Crohn's disease. Knowing that PAP I and IL-10 responses share several features, we have used a pancreatic acinar cell line (AR42J) to assess the extent to which their expression is reciprocally regulated, and whether the JAK/STAT and NF-kappaB signaling pathways are involved in the suppression of inflammation mediated by PAP I. We observed that PAP I is induced in epithelial cells by IL-10 and by PAP I itself. In contrast, we found phosphorylation and nuclear translocation of STAT3 and induction of suppressor of cytokine signaling 3 in response to PAP I exposure. Finally, a JAK-specific inhibitor, tyrphostin AG490, markedly prevented PAP I-induced NF-kappaB inhibition, pointing to a cross-talk between JAK/STAT3 and NF-kappaB signaling pathways. Together, these findings indicate that PAP I inhibits the inflammatory response by blocking NF-kappaB activation through a STAT3-dependent mechanism. Important functional similarities to the anti-inflammatory cytokine IL-10 suggest that PAP I could play a role similar to that of IL-10 in epithelial cells.

Pancreatic response to endotoxin after chronic alcohol exposure: switch from apoptosis to necrosis?

Chronic alcohol consumption is known to increase the susceptibility to acute and chronic pancreatitis, and it is likely that a cofactor is required to initiate the progression to alcoholic pancreatitis. The severity and complications of alcoholic and nonalcoholic acute pancreatitis may be influenced by a number of cofactors, including endotoxemia. To explore the effect of a possible cofactor, we used endotoxin [lipopolysaccharide (LPS)] as a tool to induce cellular injury in the alcoholic pancreas. Single, increasing doses of endotoxin were injected in rats fed an alcohol or control diet and killed 24 h after the injection. We examined the mechanism by which LPS exacerbates pancreatic injury in alcohol-fed rats and whether the injury is associated with apoptosis or necrosis. We showed that chronic alcohol exposure alone inhibits apoptosis through the intrinsic pathway and the downstream apoptosis executor caspase-3 compared with the controls. Pancreatic necrosis and inflammation increased after LPS injection in control and alcohol-fed rats in a dose-dependent fashion but with a significantly greater response in the alcohol-fed animals. Caspase activities and TdT-mediated dUTP nick-end labeling positivity were lower in the alcoholic pancreas injected with LPS, whereas the histopathology and inflammation were more severe compared with the control-fed animals. Assessment of a putative indicator of necrosis, the ratio of ADP to ATP, indicated that alcohol exposure accelerates pancreatic necrosis in response to endotoxin. These findings suggest that the pancreas exposed to alcohol is more sensitive to LPS-induced damage because of increased sensitivity to necrotic cell death rather than apoptotic cell death. Similar to the liver, the pancreas is capable of responding to LPS with a more severe response in alcohol-fed animals, favoring pancreatic necrosis rather than apoptosis. We speculate that this mechanism may occur in acute alcoholic pancreatitis patients.

Gene expression profiling in murine obliterative airway disease

Lung and heart-lung transplantation are effective treatments for many diseases unresponsive to other therapy. However, long-term survival of recipients is limited by the development of obliterative bronchiolitis (OB). In this study, microarray analysis of a heterotopic mouse model of obliterative airway disease (OAD) was used to test the hypothesis that the expression and patterns of genes will correlate with specific changes in tracheal tissue developing a response to allotransplantation and the infiltrating cells manifesting these changes. Expression profiles observed were in accordance with the current paradigm of a predictable sequence of events, beginning with airway injury; an innate immune response followed by an adaptive immune response, including both cell-mediated and humoral components; and eventual loss of airway epithelial cells. These observations confirm and expand the list of genes and molecular processes that can be studied as potential surrogate markers or targets for intervention of OB.

Binding of the Golgi sorting receptor muclin to pancreatic zymogens through sulfated O-linked oligosaccharides

Sorting and packaging of regulated secretory proteins involves protein aggregation in the trans-Golgi network and secretory granules. In this work, we characterized the pH-dependent interactions of pancreatic acinar cell-regulated secretory proteins (zymogens) with Muclin, a putative Golgi cargo receptor. In solution, purified Muclin co-aggregated with isolated zymogens at mildly acidic pH. In an overlay assay, [35S]sulfate biosynthetically labeled Muclin bound directly at mildly acidic pH to the zymogen granule content proteins amylase, prolipase, pro-carboxypeptidase A1, pro-elastase II, chymotrypsinogen B, and Reg1. Denaturation of Muclin with reducing agents to break the numerous intrachain disulfide bonds in Muclin's scavenger receptor cysteine-rich and CUB domains did not interfere with binding. Non-sulfated [35S]Met/Cys-labeled Muclin showed decreased binding in the overlay assay. Extensive Pronase E digestion of unlabeled Muclin was used to produce glycopeptides, which competed for binding of [35S]sulfate-labeled Muclin to zymogens. The results demonstrate that the sulfated, O-glycosylated groups are responsible for the pH-dependent interactions of Muclin with the zymogens. The behavior of Muclin fulfils the requirement of a Golgi cargo receptor to bind to regulated secretory proteins under the mildly acidic pH conditions that exist in the trans-Golgi network.