A family of 16-kDa pancreatic secretory stress proteins form highly organized fibrillar structures upon tryptic activation

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.

Reg3A Overexpression Facilitates Hepatic Metastasis by Altering Cell Adhesion in LoVo Colon Cancer Cells

Reg3A is upregulated in various cancers and considered a potential target for antitumor treatments. However, the effect of Reg3A in metastasis has been elusive. This study aims to disclose the role of Reg3A overexpression in hepatic metastasis of LoVo colon cancer cells. A stable cell line of LoVo cells overexpressing Reg3A (LoVo-luc-Reg3A), labeled with luc reporter gene, was constructed. Cell proliferation, apoptosis, migration, and invasion were determined using MTT, EdU, Hoechst's staining, flow cytometry, and transwell assays, respectively. Hepatic metastasis of LoVo-luc-Reg3A cells was investigated in BALB/c nude mice. Living bioluminescence imaging, histological examination, and mRNA sequencing (mRNA-seq) were performed to assess the metastatic efficiency and gene expression alteration. Reg3A content was determined by Western blotting and Enzyme-Linked Immunosorbent Assay. Cell attachment capacity was determined in the Matrigel culture. Reg3A overexpression did not promote LoVo cell proliferation or apoptosis, but facilitated cell migration and invasion. In the hepatic metastasis model, Reg3A overexpression increased the number of metastatic colonies. The result of mRNA-seq suggested 349 differentially expressed genes (DEGs) by Reg3A upregulation, many of which were related to colon adenocarcinoma tumorigenesis compared to normal colon tissue. Gene ontology enrichment assay indicated that the DEGs are mainly associated with cell adhesion, leukocyte regulation, extracellular matrix (ECM) remodeling, integrin binding, and STAT protein binding. Reg3A overexpression led to an enrichment of Reg3A protein in local tumor tissue of liver metastasis and ECM/intracellular space in ex vivo cultured cells. However, Reg3A concentration in serum and culture medium was relatively low. Reg3A overexpression also resulted in an increased number of cells that attach to Matrigel, which was attenuated by treatments of siRNA-Reg3A and single-chain variable fragment against Reg3A. Endogenous Reg3A overexpression facilitates hepatic metastasis of LoVo colon cancer cells. The prometastatic effect could be contributed by Reg3A enrichment in ECM, which alters the cell adhesion behavior.

Antimicrobial protein REG3A regulates glucose homeostasis and insulin resistance in obese diabetic mice

Innate immune mediators of pathogen clearance, including the secreted C-type lectins REG3 of the antimicrobial peptide (AMP) family, are known to be involved in the regulation of tissue repair and homeostasis. Their role in metabolic homeostasis remains unknown. Here we show that an increase in human REG3A improves glucose and lipid homeostasis in nutritional and genetic mouse models of obesity and type 2 diabetes. Mice overexpressing REG3A in the liver show improved glucose homeostasis, which is reflected in better insulin sensitivity in normal weight and obese states. Delivery of recombinant REG3A protein to leptin-deficient ob/ob mice or wild-type mice on a high-fat diet also improves glucose homeostasis. This is accompanied by reduced oxidative protein damage, increased AMPK phosphorylation and insulin-stimulated glucose uptake in skeletal muscle tissue. Oxidative damage in differentiated C2C12 myotubes is greatly attenuated by REG3A, as is the increase in gp130-mediated AMPK activation. In contrast, Akt-mediated insulin action, which is impaired by oxidative stress, is not restored by REG3A. These data highlight the importance of REG3A in controlling oxidative protein damage involved in energy and metabolic pathways during obesity and diabetes, and provide additional insight into the dual function of host-immune defense and metabolic regulation for AMP.

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.

Recombinant Reg3α Prevents Islet β-Cell Apoptosis and Promotes β-Cell Regeneration

Progressive loss and dysfunction of islet β-cells has not yet been solved in the treatment of diabetes. Regenerating protein (Reg) has been identified as a trophic factor which is demonstrated to be associated with pancreatic tissue regeneration. We previously produced recombinant Reg3α protein (rReg3α) and proved that it protects against acute pancreatitis in mice. Whether rReg3α protects islet β-cells in diabetes has been elusive. In the present study, rReg3α stimulated MIN6 cell proliferation and resisted STZ-caused cell death. The protective effect of rReg3α was also found in mouse primary islets. In BALB/c mice, rReg3α administration largely alleviated STZ-induced diabetes by the preservation of β-cell mass. The protective mechanism could be attributed to Akt/Bcl-2/-xL activation and GRP78 upregulation. Scattered insulin-expressing cells and clusters with small size, low insulin density, and exocrine distribution were observed and considered to be neogenic. In isolated acinar cells with wheat germ agglutinin (WGA) labeling, rReg3α treatment generated insulin-producing cells through Stat3/Ngn3 signaling, but these cells were not fully functional in response to glucose stimulation. Our results demonstrated that rReg3α resists STZ-induced β-cell death and promotes β-cell regeneration. rReg3α could serve as a potential drug for β-cell maintenance in anti-diabetic treatment.

The Potential Role of REG Family Proteins in Inflammatory and Inflammation-Associated Diseases of the Gastrointestinal Tract

Regenerating gene (REG) family proteins serve as multifunctional secretory molecules with trophic, antiapoptotic, anti-inflammatory, antimicrobial and probably immuno-regulatory effects. Since their discovery, accumulating evidence has clarified the potential roles of the REG family in the occurrence, progression and development of a wide range of inflammatory and inflammation-associated diseases of the gastrointestinal (GI) tract. However, significant gaps still exist due to the undefined nature of certain receptors, regulatory signaling pathways and possible interactions among distinct Reg members. In this narrative review, we first describe the structural features, distribution pattern and purported regulatory mechanisms of REG family proteins. Furthermore, we summarize the established and proposed roles of REG proteins in the pathogenesis of various inflammation-associated pathologies of the GI tract and the body as a whole, focusing particularly on carcinogenesis in the ulcerative colitis—colitic cancer sequence and gastric cancer. Finally, the clinical relevance of REG products in the context of diagnosis, treatment and prognostication are also discussed in detail. The current evidence suggests a need to better understanding the versatile roles of Reg family proteins in the pathogenesis of inflammatory-associated diseases, and their broadened future usage as therapeutic targets and prognostic biomarkers is anticipated.

Pancreatic stone protein - sepsis and the riddles of the exocrine pancreas

Pancreatic stone protein (PSP), discovered in the 1970ies, was first associated with stone formation during chronic pancreatitis. Later, the same protein was independently detected in islet preparations and named regenerating protein 1 (REG1). Additional isoforms of PSP, including pancreatitis-associated protein (PAP), belong to the same protein family. Although the names indicate a potential function in stone formation or islet regeneration, involvements in cellular processes were only suggestive and never unequivocally proven. We established an association between PSP levels in patient blood samples and the development of sepsis. In this review, written in connection with receiving the Lifetime Achievement Award of the European Pancreatic Club, the evolution of the sepsis aspect of PSP is described. We conclude that the true functional properties of this fascinating pancreatic protein still remain an enigma.

Four Decades After the Discovery of Regenerating Islet-Derived (Reg) Proteins: Current Understanding and Challenges

Regenerating islet-derived (Reg) proteins have emerged as multifunctional agents with pro-proliferative, anti-apoptotic, differentiation-inducing and bactericidal properties. Over the last 40 years since first discovered, Reg proteins have been implicated in a gamut of maladies including diabetes, various types of cancer of the digestive tract, and Alzheimer disease. Surprisingly though, a consensus is still absent on the regulation of their expression, and molecular underpinning of their function. Here, we provide a critical appraisal of recent findings in the field of Reg protein biology. Specifically, the structural characteristics are reviewed particularly in connection with established or purported functions of different members of the Reg family. Moreover, Reg expression patterns in different tissues both under normal and pathophysiological conditions are summarized. Putative receptors and cascades reported to relay Reg signaling inciting cellular responses are presented aiming at a better appreciation of the biological activities of the distinct Reg moieties. Challenges are also discussed that have hampered thus far the rapid progress in this field such as the use of non-standard nomenclature for Reg molecules among various research groups, the existence of multiple Reg members with significant degree of homology and possibly compensatory modes of action, and the need for common assays with robust readouts of Reg activity. Coordinated research is warranted going forward, given that several research groups have independently linked Reg proteins to diseased states and raised the possibility that these biomolecules can serve as therapeutic targets and biomarkers.

The pancreas responds to remote damage and systemic stress by secretion of the pancreatic secretory proteins PSP/regI and PAP/regIII

INTRODUCTION

In patients with infection and sepsis serum levels of Pancreatic Stone protein/regenerating protein I (PSP) are highly elevated. The origin of PSP during these conditions is presumably the pancreas, however, an intestinal origin cannot be excluded. Similarly, pancreatitis-associated protein (PAP) was identified in the pancreas. These proteins were also localized in intestinal organs. Here we aim to elucidate the bio-distribution of PSP and PAP in animal models of sepsis and in healthy humans.

RESULTS

PSP and PAP responded to remote lesions in rats although the pancreatic response was much more pronounced than the intestinal. Tissue distribution of PSP demonstrated a 100-fold higher content in the pancreas compared to any other organ while PAP was most abundant in the small intestine. Both proteins responded to CLP or sham operation in the pancreas. PSP also increased in the intestine during CLP. The distribution of PSP and PAP in human tissue mirrored the distribution in the murine models.

MATERIALS AND METHODS

Distribution of PSP and PAP was visualized by immunohistochemistry. Rats and mice underwent midline laparotomies followed by mobilization of tissue and incision of the pancreatic duct or duodenum. Standard cecum-ligation-puncture (CLP) procedures or sham laparotomies were performed. Human tissue extracts were analyzed for PSP and PAP.

CONCLUSIONS

The pancreas reacts to remote lesions and septic insults in mice and rats with increased PSP synthesis, while PAP is selectively responsive to septic events. Furthermore, our results suggest that serum PSP in septic patients is predominantly derived through an acute phase response of the pancreas.

Pancreatic stone protein/regenerating protein (PSP/reg): a novel secreted protein up-regulated in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) has insulin resistance (IR) or reduced β-cell mass, partially due to an increased β-cell apoptosis rate. Pancreatic stone protein/regenerating protein (PSP/reg) is a secretory protein produced in the pancreas and up-regulated dramatically during pancreatic disease. Recent studies revealed that β-cells undergoing apoptosis induce PSP/reg expression in surviving neighboring cells. Further experiments demonstrated that PSP/reg was elevated during disease progression in type 1 diabetes mellitus (T1DM). However, the association between PSP/reg and T2DM patients is unknown. The aim of this pilot study was to investigate PSP/reg in different clinical stages of T2DM and evaluate its correlation with chronic complications of diabetes. A total of 1,121 participants (479 males, 642 females; age range 23-80 years) were enrolled in this study. PSP/reg serum values were measured by a newly developed enzyme-linked immunosorbent assay (ELISA). We analyzed its correlation with clinical and biochemical parameters in subjects with T2DM at different clinical phases. Statistical analyses were conducted using SPSS 17.0 software. Correlations of PSP/reg and clinical parameters were performed using Spearman's rank correlation coefficient. Differences between groups were determined by Nemenyi test. PSP/reg was elevated in high-risk and impaired glucose regulation (IGR) patients (p<0.05). PSP/reg was significantly up-regulated in newly diagnosed T2DM patients and long-term diabetes patients with complications (p<0.001). PSP/reg levels correlated with the duration of diabetes (p<0.001). The area under the curve (AUC) for presence of diabetes-onset and its chronic complications was 0.640 and 0.754, respectively. PSP/reg is significantly up-regulated in T2DM patients, and PSP/reg levels are related to the duration of diabetes. Therefore, PSP/reg might be useful as a predictor of T2DM and disease progression.

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.

N-terminal cleaved pancreatitis-associated protein-III (PAP-III) serves as a scaffold for neurites and promotes neurite outgrowth

Pancreatitis-associated protein (PAP)-III, also known as regenerating gene/regenerating islet-derived (Reg)-IIIγ, is a small secretory protein whose expression is substantially induced in injured nerves. Here, we found that PAP-III protein underwent proteolytic N-terminal processing by trypsin-like protease(s) in injured sciatic nerves after axotomy. In vitro studies demonstrated that the N terminus-truncated PAP-III (ΔN-PAP-III) polymerized into a filament with a relatively uniform diameter of 10-20 nm, and the filaments formed higher order structures in a Na(+) concentration-dependent manner. When the ΔN-PAP-III fibers were added to the culture media, the ΔN-PAP-III fibers were tightly attached to neurites and somata of primary cortical neurons in vitro. In contrast, little association with glial cells was observed. When dense matrices of ΔN-PAP-III fibers were sheeted on a culture dish, neurites preferentially adhered to the fibers, and neurite extension was enhanced. This neurite outgrowth activity was significantly suppressed by preincubation with antibodies against PAP-III. These results imply that the released PAP-III might be cleaved and forms ΔN-PAP-III fibers at the nerve injury sites. Consequently, these resulting fibers would provide regenerating axons with a platform for extension.

Expression of pancreatitis-associated protein after traumatic brain injury: a mechanism potentially contributing to neuroprotection in human brain

Neuronal cell death after severe traumatic brain injury (TBI) is caused by a complex interplay of pathological mechanisms including excitotoxicity, oxidative stress, mitochondrial dysfunction, extensive neuroinflammation, and ischemia-reperfusion injury. Pancreatitis-associated protein I (PAP I/reg2) was reported to be a survival factor for peripheral neurons, particularly sensory and motor neurons. In rat brains, by experimental TBI as well as by kainic acid induced brain seizure, PAP I and PAP III were found to be up-regulated in central neurons. In this study, we performed immunohistochemical staining in postmortem human brain from patients who died after severe TBI to demonstrate PAP expression on protein level in cerebellar Purkinje cells, pyramidal and granular neurons in cerebral cortex, and cortical neurons in the fore- and mid-brain. In primary cultures of rat brain cortical, hippocampal, and cerebellar neurons, we found neuroprotective effects for PAP I on H(2)O(2)-induced oxidative stress. Moreover, serum K(+)-deprivation induces apoptotic cell death in 55% of cerebellar granule neurons (CGN), whereas upon treatment with PAP I only 32% of CGN are apoptotic. Using Western blot analyses, we compared protein phosphorylation in neuronal signaling pathways activated by PAP I versus Interleukin-6 (IL-6). We found a rapid activation of Akt-kinase phosphorylation by PAP I with a peak at 15 min, whereas IL-6 induces Akt-phosphorylation lasting longer than 30 min. Phosphorylation of MAP-42/44 kinases is stimulated in a comparable fashion. Both, IL-6 and PAP I increase phosphorylation of NFκB for activation of gene transcription, whereas only IL-6 recruits STAT3 phosphorylation, indicating that STAT3 is not a target of PAP I transcription activation in brain neurons. Application of the Akt-inhibitor Wortmanin reveals only a partial inhibition of PAP I-dependent protection of CGN from H(2)O(2)-induced oxidative stress. Based on our findings, we suggest that PAP I is a long lasting neurotrophic signal for central neurons. The neuroprotective effects parallel those that have been described for effects of PAP I in ciliary neurotrophic factor (CNTF)-mediated survival of sensory and motor neurons. PAP I may act in autocrine and/or paracrine fashion and thus may contribute to endogenous protective mechanisms relevant under harmful conditions like oxidative stress, brain injury, or neurodegeneration.

Pancreatic stone protein/regenerating protein family in pancreatic and gastrointestinal diseases

Pancreatic stone protein (PSP; reported in 1979), pancreatitis-associated protein (PAP; 1984) and regenerating protein (Reg I; 1988) were discovered independently in the fields of the exocrine (pancreatitis) and endocrine (diabetes) pancreas. Subsequent analysis revealed that PSP and Reg I are identical and PAP belongs to the same protein family. PSP/Reg I and PAP share a selective and specific trypsin cleavage site and result in insoluble fibrils (PTP, PATP). Search for a functional role of PSP had led to the idea that it might serve as an inhibitor in pancreatic stone formation and PSP was renamed lithostathine. Inhibitory effects of lithostathine in stone formation have been questioned. Evidence so far obtained can support a lithogenic role rather than a lithostatic role of PSP. PAP and its isoforms have been investigated mainly regarding responses to inflammation and stress. Reg I and its isoforms have been examined on regeneration, growth and mitogenesis in gastrointestinal neoplastic diseases as well as diabetes. Evidence obtained can be applied in the prediction of prognosis and therapy for inflammatory and neoplastic diseases.

INS-1 cells undergoing caspase-dependent apoptosis enhance the regenerative capacity of neighboring cells

OBJECTIVE

In diabetes, β-cell mass is not static but in a constant process of cell death and renewal. Inactivating mutations in transcription factor 1 (tcf-1)/hepatocyte nuclear factor1a (hnf1a) result in decreased β-cell mass and HNF1A-maturity onset diabetes of the young (HNF1A-MODY). Here, we investigated the effect of a dominant-negative HNF1A mutant (DN-HNF1A) induced apoptosis on the regenerative capacity of INS-1 cells.

RESEARCH DESIGN AND METHODS

DN-HNF1A was expressed in INS-1 cells using a reverse tetracycline-dependent transactivator system. Gene(s)/protein(s) involved in β-cell regeneration were investigated by real-time quantitative RT-PCR, Western blotting, and immunohistochemistry. Pancreatic stone protein/regenerating protein (PSP/reg) serum levels in human subjects were detected by enzyme-linked immunosorbent assay.

RESULTS

We detected a prominent induction of PSP/reg at the gene and protein level during DN-HNF1A-induced apoptosis. Elevated PSP/reg levels were also detected in islets of transgenic HNF1A-MODY mice and in the serum of HNF1A-MODY patients. The induction of PSP/reg was glucose dependent and mediated by caspase activation during apoptosis. Interestingly, the supernatant from DN-HNF1A-expressing cells, but not DN-HNF1A-expressing cells treated with zVAD.fmk, was sufficient to induce PSP/reg gene expression and increase cell proliferation in naïve, untreated INS-1 cells. Further experiments demonstrated that annexin-V-positive microparticles originating from apoptosing INS-1 cells mediated the induction of PSP/reg. Treatment with recombinant PSP/reg reversed the phenotype of DN-HNF1A-induced cells by stimulating cell proliferation and increasing insulin gene expression.

CONCLUSIONS

Our results suggest that apoptosing INS-1 cells shed microparticles that may stimulate PSP/reg induction in neighboring cells, a mechanism that may facilitate the recovery of β-cell mass in HNF1A-MODY.

Altered gene expression in cerulein-stimulated pancreatic acinar cells: pathologic mechanism of acute pancreatitis

Acute pancreatitis is a multifactorial disease associated with the premature activation of digestive enzymes. The genes expressed in pancreatic acinar cells determine the severity of the disease. The present study determined the differentially expressed genes in pancreatic acinar cells treated with cerulein as an in vitro model of acute pancreatitis. Pancreatic acinar AR42J cells were stimulated with 10(-8) M cerulein for 4 h, and genes with altered expression were identified using a cDNA microarray for 4,000 rat genes and validated by real-time PCR. These genes showed a 2.5-fold or higher increase with cerulein: lithostatin, guanylate cyclase, myosin light chain kinase 2, cathepsin C, progestin-induced protein, and pancreatic trypsin 2. Stathin 1 and ribosomal protein S13 showed a 2.5-fold or higher decreases in expression. Real-time PCR analysis showed time-dependent alterations of these genes. Using commercially available antibodies specific for guanylate cyclase, myosin light chain kinase 2, and cathepsin C, a time-dependent increase in these proteins were observed by Western blotting. Thus, disturbances in proliferation, differentiation, cytoskeleton arrangement, enzyme activity, and secretion may be underlying mechanisms of acute pancreatitis.

Ileal mucosal and fecal pancreatitis associated protein levels reflect severity of salmonella infection in rats

BACKGROUND

Microbial infections induce ileal pancreatitis-associated protein/regenerating gene III (PAP/RegIII) mRNA expression. Despite increasing interest, little is known about the PAP/RegIII protein. Therefore, ileal mucosal PAP/RegIII protein expression, localization, and fecal excretion were studied in rats upon Salmonella infection.

RESULTS

Salmonella infection increased ileal mucosal PAP/RegIII protein levels in enterocytes located at the crypt-villus junction. Increased colonization and translocation of Salmonella was associated with higher ileal mucosal PAP/RegIII levels and secretion of this protein in feces.

CONCLUSIONS

PAP/RegIII protein is increased in enterocytes of the ileal mucosa during Salmonella infection and is associated with infection severity. PAP/RegIII is excreted in feces and might be used as a new and non-invasive infection marker.

Acidic and basic solutions dissolve protein plugs made of lithostathine complicating choledochal cyst/pancreaticobiliary maljunction

BACKGROUND

Symptoms of choledochal cysts are caused by protein plugs made of lithostathine, which block the long common channel and increase pancreaticobiliary ductal pressure. Agents that dissolve protein plugs can provide relief from or prevent symptoms. In the present study, drugs reportedly effective for pancreatic and biliary stones were used in dissolution tests.

METHODS

Protein plugs were obtained from choledochal cysts during surgery in two children (5- and 6-year-old girls). Plugs approximately 2 mm in diameter were immersed in citric acid, tartaric acid, dimethadione, bromhexine, dehydrocholic acid, sodium citrate, hydrochloric acid, and sodium hydroxide solutions under observation with a digital microscope. The pH of each solution was measured using a pH meter.

RESULTS

Plugs dissolved in citric acid (5.2 mM; pH 2.64), tartaric acid (6.7 mM; pH 2.51), dimethadione (75 mM; pH 3.70), hydrochloric acid (0.5 mM; pH 3.13), and sodium hydroxide (75 mM; pH 12.75) solutions. Plugs did not dissolve in dimethadione (7.5 mM; pH 4.31), bromhexine (0.1%; pH 4.68), dehydrocholic acid (5%; pH 7.45), and sodium citrate (75 mM; pH 7.23) solutions.

CONCLUSION

Protein plugs in choledochal cysts are dissolved in acidic and basic solutions, which may eliminate longitudinal electrostatic interactions of the lithostathine protofibrils.

Proteolytic activation of human pancreatitis-associated protein is required for peptidoglycan binding and bacterial aggregation

PAP (pancreatitis-associated protein) is a 16 kDa lectin-like protein, which becomes robustly up-regulated in the pancreatic juice during acute pancreatitis. Trypsin cleaves the N-terminus of PAP, which in turn forms insoluble fibrils. PAP and its paralogue, the pancreatic stone protein, induce bacterial aggregation and, more recently, PAP was shown to bind to the peptidoglycan of Gram-positive bacteria and exert a direct bactericidal effect. However, the role of N-terminal processing in the antibacterial function of PAP has remained unclear. In the present study, we demonstrate that N-terminal cleavage of PAP by trypsin at the Arg37-Ile38 peptide bond or by elastase at the Ser35-Ala36 peptide bond is a prerequisite for binding to the peptidoglycan of the Gram-positive bacterium Bacillus subtilis. The tryptic site in PAP was also efficiently cleaved by nprE (extracellular neutral metalloprotease) secreted from B. subtilis. Trypsin-mediated processing of PAP resulted in the formation of the characteristic insoluble PAP species, whereas elastase-processed PAP remained soluble. N-terminally processed PAP induced rapid aggregation of B. subtilis without significant bacterial killing. The bacteria-aggregating activities of trypsin-processed and elastase-processed PAP were comparable. In contrast with previous reports, the Gram-negative Escherichia coli bacterium was not aggregated. We conclude that N-terminal processing is necessary for the peptidoglycan binding and bacteria-aggregating activity of PAP and that trypsin-processed and elastase-processed forms are functionally equivalent. The observations also extend the complement of proteases capable of PAP processing, which now includes trypsins, pancreatic elastases and bacterial zinc metalloproteases of the thermolysin type.

Regulation of C-type lectin antimicrobial activity by a flexible N-terminal prosegment

Members of the RegIII family of intestinal C-type lectins are directly antibacterial proteins that play a vital role in maintaining host-bacterial homeostasis in the mammalian gut, yet little is known about the mechanisms that regulate their biological activity. Here we show that the antibacterial activities of mouse RegIIIgamma and its human ortholog, HIP/PAP, are tightly controlled by an inhibitory N-terminal prosegment that is removed by trypsin in vivo. NMR spectroscopy revealed a high degree of conformational flexibility in the HIP/PAP inhibitory prosegment, and mutation of either acidic prosegment residues or basic core protein residues disrupted prosegment inhibitory activity. NMR analyses of pro-HIP/PAP variants revealed distinctive colinear backbone amide chemical shift changes that correlated with antibacterial activity, suggesting that prosegment-HIP/PAP interactions are linked to a two-state conformational switch between biologically active and inactive protein states. These findings reveal a novel regulatory mechanism governing C-type lectin biological function and yield new insight into the control of intestinal innate immunity.

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.

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.

Small-interference RNA gene knockdown of pancreatitis-associated proteins in rat acute pancreatitis

OBJECTIVES

Pancreatitis-associated proteins (PAPs) are induced in acute pancreatitis and antisense-mediated gene knockdown of PAP decreased PAP gene expression and worsened pancreatitis. Here, we investigated the effect of a more stable inhibition of PAP using small-interference RNA gene knockdown in vitro and in an in vivo model of experimental pancreatitis.

METHODS

Pancreatitis-associated protein-specific siRNA was administered to AR42J cell cultures or rats induced with pancreatitis. Controls included administration of scrambled siRNA or vehicle alone. After 24 hours, cells and pancreata were harvested and assessed for PAP (PAP 1, PAP 2, PAP 3) gene expression and pancreatitis severity.

RESULTS

In vitro, PAP protein, and mRNA levels were reduced (PAP 1, 76%; PAP 2, 8%; PAP 3, 24%) in cells treated with PAP siRNA. In vivo, PAP 1, and PAP 3 expressions were reduced (PAP 1, 36%; PAP 3, 66%) in siRNA-treated rats; there was no difference in PAP 2 isoform mRNA expression and serum protein levels. Serum amylase and lipase levels decreased (> or =50%) after administration of siRNA; interleukin (IL) 1beta, IL-4, and IL-6 increased, whereas C-reactive protein and tumor necrosis factor-alpha decreased when compared with vehicle control. Administration of PAP siRNA correlated with worsening histopathology.

CONCLUSIONS

siRNA-mediated gene knockdown of PAP worsens pancreatitis. Differences in gene knockdown technology may provide different approaches to study gene function.

Endoscopic sphincterotomy is a useful preoperative management for refractory pancreatitis associated with pancreaticobiliary maljunction

BACKGROUND

Pancreatitis associated with pancreaticobiliary maljunction (PBM) is commonly treated nonoperatively before surgery. It is, however, sometimes uncontrollable, and little has been reported about the management.

METHODS

Focusing on the preoperative management, we reviewed clinical courses of 4 PBM cases (ages 1 to 7 years old). Each had pancreatitis that was totally resistant to medical treatment and was applied endoscopic sphincterotomy (ES).

RESULTS

The first case underwent percutaneous transhepatic catheter drainage (PTCD) primarily. In spite of daily lavage using the drainage tube for a week, plugs located in the common channel were not removed, and clinical findings were not improved. Therefore, ES followed by removal of protein plugs was performed to improve pancreatitis dramatically. Through this experience, 3 subsequent cases with refractory pancreatitis all underwent successful ES primarily soon after the medical treatments turned out to be ineffective. In all 4 cases, protein plugs were impacted in common channels, and ES could successfully remove the plugs that were impossible to remove by using PTCD. Improved preoperative pancreaticobiliary decompression by ES shortens the duration of recalcitrant acute pancreatitis associated with PBM allowing for a subsequent safe operation.

CONCLUSIONS

Endoscopic sphincterotomy is one of the useful preoperative managements for refractory pancreatitis associated with PBM.

Proteomic analysis of protein plugs: causative agent of symptoms in patients with choledochal cyst

Symptoms of choledochal cysts are caused by protein plugs. We performed proteomic analysis of protein plugs to elucidate formation mechanism. Protein plugs were obtained from three pediatric patients with choledochal cyst. Proteins were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Gel bands common to the samples were excised for mass spectrometry. Mass spectra were compared with the NCBI database for protein identification. Gel bands of protein plug samples were predominant at 14 kilodaltons (kDa), followed by 29 kDa. Four other thin bands were common to the plug samples. Four bands (including 14 and 29 kDa) were identified as lithostathine, and one band as serum albumin. Plugs consisted mostly of lithostathine, a protein secreted by pancreatic acinar cells into pancreatic juice. The mechanism involves trypsinogen and lithostathine regurgitating into the cyst through an aberrant union of pancreaticobiliary ducts. Activated trypsin cleaves soluble lithostathine into insoluble forms that aggregate to form plugs.

Is genetic analysis helpful for diagnosing chronic pancreatitis in its early stage?

Diagnosis of chronic pancreatitis in its early stage is an extremely difficult task. If the genetic predispositions are identified, it may help make possible the earlier diagnosis of chronic pancreatitis or the detection of patients at risk. There are two major hypotheses about the pathogenesis of chronic pancreatitis known as the "necrosis-fibrosis" and "pancreatic stone protein" hypotheses. Recent molecular and genetic evidence suggests that both pathways contribute to the pathogenesis of chronic pancreatitis. Chronic pancreatitis may be caused by either increased proteolytic activity [the cationic trypsinogen (PRSS1) gene] or decreased protease inhibition (the pancreatic secretory trypsin inhibitor (PSTI) gene]. The impaired pancreatic duct function [cystic fibrosis transmembrane conductance regulator (CFTR) gene] may also be involved in the pathogenesis of the disease. Except for PRSS1 mutations, the known genetic risk for chronic pancreatitis is not high. The high individual variability and low incidence of chronic pancreatitis suggest that yet unidentified genetic and environmental factors are important. Further genetic analysis is necessary for understanding the pathogenesis of chronic pancreatitis, which may be helpful for the earlier diagnosis of the juvenile- or young-onset disease.

Human pancreatitis-associated protein forms fibrillar aggregates with a native-like conformation

Human pancreatitis-associated protein was identified in pathognomonic lesions of Alzheimer disease, a disease characterized by the presence of filamentous protein aggregates. Here, we showed that at physiological pH, human pancreatitis-associated protein forms non-Congo Red-binding, proteinase K-resistant fibrillar aggregates with diameters from 6 up to as large as 68 nm. Interestingly, circular dichroism and Fourier transform infrared spectra showed that, unlike typical amyloid fibrils, which have a cross-beta-sheet structure, these aggregates have a very similar secondary structure to that of the native protein, which is composed of two alpha-helices and eight beta-strands, as determined by NMR techniques. Surface structure analysis showed that the positively charged and negatively charged residues were clustered on opposite sides, and strong electrostatic interactions between molecules were therefore very likely, which was confirmed by cross-linking experiments. In addition, several hydrophobic residues were found to constitute a continuous hydrophobic surface. These results and protein aggregation prediction using the TANGO algorithm led us to synthesize peptide Thr(84) to Ser(116), which, very interestingly, was found to form amyloid-like fibrils with a cross-beta structure. Thus, our data suggested that human pancreatitis-associated protein fibrillization is initiated by protein aggregation primarily because of electrostatic interactions, and the loop from residues 84 to 116 may play an important role in the formation of fibrillar aggregates with a native-like conformation.

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 Reg3α, and 10-fold greater PAP/Reg3β and Reg3γ). 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, Reg3α was strongly expressed in the untreated CF pancreas but not in wild type. During pancreatitis, Reg3α 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.

Potential protein markers for nutritional health effects on colorectal cancer in the mouse as revealed by proteomics analysis

It is suggested that colorectal cancer might be prevented by changes in diet, and vegetable consumption has been demonstrated to have a protective effect. Until now, little is known about the effects of vegetable consumption at the proteome level. Therefore, the effect of increased vegetable intake on the protein expression in the colonic mucosa of healthy mice was studied. Aim was to identify the proteins that are differentially expressed by increased vegetable consumption and to discriminate their possible role in the protection against colorectal cancer. Mice were fed four different vegetable diets, which was followed by analysis of total cellular protein from colonic mucosal cells by a combination of 2-DE and MS. We found 30 proteins that were differentially expressed in one or more diets as compared to the control diet. Six could be identified by MALDI-TOF MS: myosin regulatory light chain 2, carbonic anhydrase I, high-mobility group protein 1, pancreatitis-associated protein 3, glyceraldehyde-3-phosphate dehydrogenase and ATP synthase oligomycin sensitivity conferral protein. Alterations in the levels of these proteins agree with a role in the protection against colon cancer. We conclude that these proteins are suitable markers for the health effect of food on cancer. The observed altered protein levels therefore provide support for the protective effects of vegetables against colorectal cancer.

Expression of Reg/PAP family members during motor nerve regeneration in rat

In this study, we examined the expression of mRNAs for Regenerating gene (Reg)/pancreatitis-associated protein (PAP) family members following hypoglossal nerve injury in rats. In addition to four rat family members (RegI, Reg-2/PAP I, PAP II, and PAP III) that had been identified, we newly cloned and sequenced a type-IV Reg gene in rats. Among these five family members, the expression of Reg-2/PAP I mRNA was predominantly enhanced in injured motor neurons after axotomy. Furthermore, a marked induction of PAP III mRNA was observed in the distal part of the injured nerve. A polyclonal antibody was raised against PAP III, and a Western blotting analysis using this antibody confirmed an increased level of PAP III protein in the injured nerve. These results suggest that Reg family members would be new mediators among injured neurons and glial cells, and may play pivotal roles during nerve regeneration.

The multifunctional family of secreted proteins containing a C-type lectin-like domain linked to a short N-terminal peptide

PSP/Lithostathine/PTP/regI, PAP/p23/HIP, reg1L, regIV and "similar to PAP" are the members of a multifunctional family of secreted proteins containing a C-type lectin-like domain linked to a short N-terminal peptide. The expression of this group of proteins is controlled by complex mechanisms, some members being constitutively expressed in certain tissues while, in others, they require activation by several factors. These members have several apparently unrelated biological effects, depending on the member studied and the target cell. These proteins may act as mitogenic, antiapoptotic or anti-inflammatory factors, can regulate cellular adhesion, promote bacterial aggregation, inhibit CaCO3 crystal growth or increase resistance to antitumoral agents. The presence of specific receptors for these proteins is suggested because biological effects were observed after the addition of purified protein to culture media or after systemic administration to animals, whereas other biological effects could be explained by their biochemical capacity to form homo or heteromers or to form insoluble fibrils at physiological pH.

Activated pancreatic enzyme and pancreatic stone protein (PSP/reg) in bile of patients with pancreaticobiliary maljunction/ choledochal cysts

Symptoms of pancreaticobiliary maljunction/choledochal cysts are caused by the obstruction of bile and pancreatic ducts due to protein plugs compacted in the common channel. However, the mechanism of protein plug formation remains unknown. Pancreatic stone protein (PSP) is reported to be a key protein to form protein plugs in chronic pancreatitis. Bile from 13 patients with pancreaticobiliary maljunction and bile from two normal controls were analyzed. Activity of pancreatic enzymes and the concentration of PSP were measured. The mean concentrations of PSP were 76.9+/-30.9 ng/mL in the bile-duct bile, and 76.9+/-29.8 ng/mL in the gallbladder bile. PSP was not detected in the controls (P < 0.05). In the bile-duct bile of the patients, trypsin(ogen) was detectable in nine patients, of which seven patients had activated trypsin. In the gallbladder bile, trypsin(ogen) was detectable in 12 patients, of which 9 patients had activated trypsin. Neither activated trypsin nor trypsinogen was detected in the controls. Bile in pancreaticobiliary maljunction patients contained both activated trypsin and PSP. Activated trypsin cleaves soluble PSP and creates insoluble PSP. Protein plugs in pancreaticobiliary maljunction may be formed by assembled insoluble PSP.

Pathogenesis of chronic pancreatitis: an evidence-based review of past theories and recent developments

In the past several decades, four prominent theories of chronic pancreatitis pathogenesis have emerged: the toxic-metabolic theory, the oxidative stress hypothesis, the stone and duct obstruction theory, and the necrosis-fibrosis hypothesis. Although these traditional theories are formulated based on compelling scientific observations, substantial contradictory data also exist for each. Furthermore, the basic premises of some of these theories are directly contradictory. Because of the recent scientific progress in the underlying genetic, cellular, and molecular pathophysiology, there have been substantial advances in the understanding of chronic pancreatitis pathogenesis. This paper will provide an evidence-based review and critique of the traditional pathogenic theories, followed by a discussion of the new advances in pancreatic fibrogenesis. Moreover, we will discuss plausible pathogenic sequences applied to each of the known etiologies.

Control of expression of the lectin-like protein Reg-1 by gastrin: role of the Rho family GTPase RhoA and a C-rich promoter element

The expression of members of the Reg family of secreted lectin-like proteins is increased in response to stress, inflammation and damage in many tissues. In the stomach, Reg is located in enterochromaffin-like cells, where its expression is stimulated by the gastric hormone gastrin. We have examined the mechanisms by which gastrin stimulates expression of Reg-1. Deletional mutations of 2.1 to 0.1 kb of the rat Reg-1 promoter in a luciferase reporter vector were transiently transfected into gastric cancer AGS-G(R) cells. All promoter fragments tested showed similar relative increases in luciferase expression in response to gastrin (1 nM). The response to gastrin of the smallest (104 bp) construct was 4.2+/-0.4-fold over basal. These responses were reduced by Ro-32-0432, a protein kinase C inhibitor, by C3-transferase, a Clostridium botulinum toxin and a selective inhibitor of the Rho family GTPase RhoA, and by co-transfection with a dominant negative form of RhoA. Co-transfection with a constitutively active form of RhoA stimulated expression 11.6+/-1.7-fold over basal. Mutations through the 104 bp construct identified a C-rich element (C-79CCCTCCC-72) required for responses to gastrin, PKC (protein kinase C) and L63RhoA (the constitutively active form of human RhoA protein containing a glutamine-to-leucine substitution at position 63). EMSAs (electrophoretic-mobility-shift assays) using nuclear extracts of control and gastrin-stimulated AGS-G(R) cells and a probe spanning -86 to -64 bp revealed multiple binding proteins. There was no effect of gastrin on the pattern of binding. Supershift assays indicated that transcription factors Sp1 and Sp3 bound the C-rich sequence. We conclude that gastrin stimulates Reg expression via activation of PKC and RhoA, that a C-rich region (-79 to -72) is critical for the response and that Sp-family transcription factors bind to this region of the promoter.

Differential expression of the trypsin inhibitor SPINK3 mRNA and the mouse ortholog of secretory granule protein ZG-16p mRNA in the mouse pancreas after repetitive injury

A mouse model using repetitive acinar cell injury caused by supraphysiologic doses of cerulein to induce the characteristic fibrosis and loss of acinar cell mass found in human chronic pancreatitis was employed to identify early changes in gene expression. A gene array was used to detect changes in 18,000 expressed sequence tags; changes in specific transcripts were confirmed by RNase protection assays. These methods identified SPINK3, the mouse homologue of human and rat protease inhibitor genes, as being highly expressed in the pancreas and induced after pancreatic injury. Because SPINK3 may be an important serine protease inhibitor, its up-regulation may reflect an important endogenous cytoprotective mechanism in preventing further injury. The up-regulation of SPINK3 was specific; the mouse homologue of the zymogen-processing protein ZG-16p was also highly expressed in the pancreas but sharply down-regulated early in the course of injury. These findings suggest that the pancreatic acinar cell may respond to injury with a program of self-preservation and loss of normal function.

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

BACKGROUND

PSP/reg and PAP are secretory stress proteins (SSP) and may be part of a protective mechanism. They share structural homologies and form insoluble fibrils after tryptic activation. To further explore the regulation of these proteins, we investigated the male WBN/Kob rat, a model of pancreatic inflammatory and fibrotic disease similar to chronic pancreatitis.

MATERIALS AND METHODS

Expression of PSP/reg and PAP I, II and III in the WBN/Kob rat pancreas was evaluated on the mRNA and protein level, by immunohistochemistry and by highly sensitive isoform specific ELISAs.

RESULTS

The SSPs are constitutively secreted, PAP in nanomolar, PSP/reg in micromolar concentrations. Before conventional morphological changes are detectable in the WBN/Kob rat, focally increased expression of secretory stress protein is visible. SSP levels in pancreatic juice of WBN/Kob rats reach peak values 10- to 50-fold higher than in Wistar control rats. The highest expression was localized to acini with inflammatory infiltration.

CONCLUSIONS

There is a tight spatial and temporal association between pre-inflammatory changes or inflammation and SSP-expression. These results support our concept that PSP/reg and PAP are coordinately regulated SSP.

Coordinate regulation of secretory stress proteins (PSP/reg, PAP I, PAP II, and PAP III) in the rat exocrine pancreas during experimental acute pancreatitis

BACKGROUND

Pancreatic stone protein (PSP/reg) is a constitutively secreted protein in pancreatic juice. Pancreatitis-associated protein (PAP) belongs to the same family of proteins. PAP is highly increased during acute pancreatitis, while no exact data exist regarding PSP/reg protein synthesis and secretion. Recently, an attempt to determine PSP/reg and PAP levels in sera of rats with acute pancreatitis showed a significant increase in PAP but failed to demonstrate changes in PSP/reg. Others reported that surgical manipulation of the pancreas, including sham controls, affected mRNA levels of PSP/reg. Neither report determined protein levels of PSP/reg.

METHODS

Rats were treated intraperitoneally with a supramaximal dose of caerulein to induce pancreatitis, a physiological dose of caerulein, or a saline injection. Pancreata were analyzed for PAP and PSP/reg using ELISAs. RNA was extracted for Northern blot analysis of PAP I, II, and III and PSP/reg mRNA.

RESULTS

Experimental induction of acute pancreatitis caused a coordinate increase in both PSP/reg and PAP. PAP showed an acute response and returned to low levels within 48 h while PSP/reg exhibited a more sustained response. Intraperitoneal application of a physiological dose of caerulein and even a saline injection caused an increase in PSP/reg.

CONCLUSION

PSP/reg and PAP levels are increased through similar mechanisms by physiological and supramaximal doses of caerulein. However, PSP/reg regulation appears to sustain high levels while PAP levels are more transient. Since the regulation of this protein family is affected even under mild stress, we define them as secretory stress proteins.

Hereditary pancreatitis: a model for inflammatory diseases of the pancreas

Acute and chronic pancreatitis remain among the most recalcitrant of all diseases to investigation and intervention. In the majority of patients, excessive alcohol consumption is associated with development of the disease. Therefore, several theories have been proposed seeking to explain the relationship between alcohol and the development of acute and chronic pancreatitis. However, recent investigations in hereditary pancreatitis provided important insights into chronic pancreatitis pathogenesis and offer an important model for understanding pancreatic inflammation. This article highlights several advances gained from investigating hereditary pancreatitis kindreds, and reviews the TIGAR-O risk/aetiology classification system. Finally, the major independent theories on development of chronic pancreatitis are reviewed with respect to the SAPE hypothesis of chronic pancreatitis pathogenesis.