Polygenic and multifactorial scores for pancreatic ductal adenocarcinoma risk prediction.

BACKGROUND: Most cases of pancreatic ductal adenocarcinoma (PDAC) are asymptomatic in early stages, and the disease is typically diagnosed in advanced phases, resulting in very high mortality. Tools to identify individuals at high risk of developing PDAC would be useful to improve chances of early detection. OBJECTIVE: We generated a polygenic risk score (PRS) for PDAC risk prediction, combining the effect of known risk SNPs, and carried out an exploratory analysis of a multifactorial score. METHODS: We tested the associations of the individual known risk SNPs on up to 2851 PDAC cases and 4810 controls of European origin from the PANcreatic Disease ReseArch (PANDoRA) consortium. Thirty risk SNPs were included in a PRS, which was computed on the subset of subjects that had 100% call rate, consisting of 839 cases and 2040 controls in PANDoRA and 6420 cases and 4889 controls from the previously published Pancreatic Cancer Cohort Consortium I-III and Pancreatic Cancer Case-Control Consortium genome-wide association studies. Additional exploratory multifactorial scores were constructed by complementing the genetic score with smoking and diabetes. RESULTS: The scores were associated with increased PDAC risk and reached high statistical significance (OR=2.70, 95% CI 1.99 to 3.68, p=2.54×10-10 highest vs lowest quintile of the weighted PRS, and OR=14.37, 95% CI 5.57 to 37.09, p=3.64×10-8, highest vs lowest quintile of the weighted multifactorial score). CONCLUSION: We found a highly significant association between a PRS and PDAC risk, which explains more than individual SNPs and is a step forward in the direction of the construction of a tool for risk stratification in the population.

Genetic analysis of the bicarbonate secreting anion exchanger SLC26A6 in chronic pancreatitis.

BACKGROUND: Pancreatic ductal HCO3(-) secretion is critically dependent on the cystic fibrosis transmembrane conductance regulator chloride channel (CFTR) and the solute-linked carrier 26 member 6 anion transporter (SLC26A6). Deterioration of HCO3(-) secretion is observed in chronic pancreatitis (CP), and CFTR mutations increase CP risk. Therefore, SLC26A6 is a reasonable candidate for a CP susceptibility gene, which has not been investigated in CP patients so far. METHODS: As a first screening cohort, 106 subjects with CP and 99 control subjects with no pancreatic disease were recruited from the Hungarian National Pancreas Registry. In 60 non-alcoholic CP cases the entire SLC26A6 coding region was sequenced. In the Hungarian cohort variants c.616G > A (p.V206M) and c.1191C > A (p.P397=) were further genotyped by restriction fragment length polymorphism analysis. In a German replication cohort all exons were sequenced in 40 non-alcoholic CP cases and variant c.616G > A (p.V206M) was further analyzed by sequencing in 321 CP cases and 171 controls. RESULTS: Sequencing of the entire coding region revealed four common variants: intronic variants c.23 + 78_110del, c.183-4C > A, c.1134 + 32C > A, and missense variant c.616G > A (p.V206M) which were found in linkage disequilibrium indicating a conserved haplotype. The distribution of the haplotype did not show a significant difference between patients and controls in the two cohorts. A synonymous variant c.1191C > A (p.P397=) and two intronic variants c.1248 + 9_20del and c.-10C > T were detected in single cases. CONCLUSION: Our data show that SLC26A6 variants do not alter the risk for the development of CP.

[Autoimmune pancreatitis. Evidence based management guidelines of the Hungarian Pancreatic Study Group]. / Autoimmun pancreatitis. A Magyar Hasnyálmirigy Munkacsoport bizonyítékon alapuló kezelési irányelvei.

Autoimmune pancreatitis is a rare disease which can even mimic pancreatic tumor, however, unlike the latter, it requires not surgical but conservative management. Correct diagnosis and differential diagnosis of autoimmune pancreatitis and treatment of these patients requires up-to-date and evidence based management guidelines. The Hungarian Pancreatic Study Group proposed to prepare an evidence based guideline based on the available international guidelines and evidences. The preparatory and consultation task force appointed by the Hungarian Pancreatic Study Group translated and complemented and/or modified the international guidelines if it was necessary. 29 relevant clinical questions in 4 topics were defined (Basics; Diagnosis; Differential diagnostics; Therapy). Evidence was classified according to the UpToDate(®) grading system. The draft of the guidelines was presented and discussed at the consensus meeting on September 12, 2014. All clinial questions were accepted with almost total (more than 95%) agreement. The present guideline is the first evidence based autoimmune pancreatitis guideline in Hungary. The guideline may provide very important and helpful data for tuition of autoimmune pancreatitis, for everyday practice and for establishing proper finance. Therefore, the authors believe that these guidelines will widely become a basic reference in Hungary.

[Pediatric pancreatitis. Evidence based management guidelines of the Hungarian Pancreatic Study Group]. / Gyermekkori pancreatitis. A Magyar Hasnyálmirigy Munkacsoport bizonyítékon alapuló kezelési irányelvei.

Pediatric pancreatitis is a rare disease with variable etiology. In the past 10-15 years the incidence of pediatric pancreatitis has been increased. The management of pediatric pancreatitis requires up-to-date and evidence based management guidelines. The Hungarian Pancreatic Study Group proposed to prepare an evidence based guideline based on the available international guidelines and evidences. The preparatory and consultation task force appointed by the Hungarian Pancreatic Study Group translated and complemented and/or modified the international guidelines if it was necessary. In 8 clinical topics (diagnosis; etiology; prognosis; imaging; therapy; biliary tract management; complications; chronic pancreatitis) 50 relevant questions were defined. Evidence was classified according to the UpToDate(®) grading system. The draft of the guidelines was presented and discussed at the consensus meeting on September 12, 2014. All clinical statements were accepted with total (more than 95%) agreement. The present Hungarian Pancreatic Study Group guideline is the first evidence based pediatric pancreatitis guideline in Hungary. The present guideline is the first evidence-based pancreatic cancer guideline in Hungary that provides a solid ground for teaching purposes, offers quick reference for daily patient care in pediatric pancreatitis and guides financing options. The authors strongly believe that these guidelines will become a standard reference for pancreatic cancer treatment in Hungary.

[Pancreatic cancer. Evidence based management guidelines of the Hungarian Pancreatic Study Group]. / Pancreasrák. A Magyar Hasnyálmirigy Munkacsoport bizonyítékon alapuló kezelési irányelvei.

Pancreatic cancer is a disease with a poor prognosis usually diagnosed at a late stage. Therefore, screening, diagnosis, treatment and palliation of pancreatic cancer patients require up-to-date and evidence based management guidelines. The Hungarian Pancreatic Study Group proposed to prepare an evidence based guideline based on the available scientific evidence and international guidelines. The preparatory and consultation board appointed by the Hungarian Pancreatic Study Group translated and complemented/modified the recent international guidelines. 37 clinical statements in 10 major topics were defined (Risk factors and genetics, Screening, Diagnosis, Staging, Surgical care, Pathology, Systemic treatment, Radiation therapy, Palliation and supportive care, Follow-up and recurrence). Evidence was graded according to the National Comprehensive Cancer Network (NCCN) grading system. The draft of the guideline was presented and discussed at the consensus meeting in September 12, 2014. Statements were accepted with either total (more than 95% of votes, n = 15) or strong agreement (more than 70% of votes, n = 22). The present guideline is the first evidence-based pancreatic cancer guideline in Hungary that provides a solid ground for teaching purposes, offers quick reference for daily patient care and guides financing options. The authors strongly believe that these guidelines will become a standard reference for pancreatic cancer treatment in Hungary.

[Acute pancreatitis. Evidence-based practice guidelines, prepared by the Hungarian Pancreatic Study Group]. / Akut pancreatitis. A Magyar Hasnyálmirigy Munkacsoport bizonyítékon alapuló kezelési irányelvei.

Acute pancreatitis is one of the most common diseases of the gastrointestinal tract associated with significant morbidity and mortality that requires up-to-date and evidence based treatment guidelines. The Hungarian Pancreatic Study Group proposed to prepare evidence based guideline for the medical and surgical management of acute pancreatitis based on the available international guidelines and evidence. The preparatory and consultation task force appointed by the Hungarian Pancreatic Study Group translated and, if it was necessary, complemented and/or modified the international guidelines. All together 42 relevant clinical questions were defined in 11 topics (Diagnosis and etiology, Prognosis, Imaging, Fluid therapy, Intensive care management, Prevention of infectious complications, Nutrition, Biliary interventions, Post-endoscopic retrograde cholangio-pancreatography pancreatitis, Indication, timing and strategy for intervention in necrotizing pancreatitis, Timing of cholecystectomy [or endoscopic sphincterotomy]). Evidence was classified according to the UpToDate® grading system. The draft of the guideline was presented and discussed at the consensus meeting on September 12, 2014. 25 clinical questions with almost total (more than 95%) and 17 clinical questions with strong (more than 70%) agreement were accepted. The present guideline is the first evidence based acute pancreatitis guideline in Hungary. The guideline may provide important help for tuition, everyday practice and for establishment of proper finance of acute pancreatitis. Therefore, the authors believe that these guidelines will widely become as basic reference in Hungary.

[Chronic pancreatitis. Evidence based management guidelines of the Hungarian Pancreatic Study Group]. / Krónikus pancreatitis. A Magyar Hasnyálmirigy Munkacsoport bizonyítékon alapuló kezelési irányelvei.

Chronic pancreatitis is an inflammatory disease associated with structural and functional damage of the pancreas. In most cases pain, maldigestion and weight loss are the leading symptoms, which significantly worsen the quality of life. Correct diagnosis and differential diagnosis of chronic pancreatitis and treatment of these patients requires up-to-date and evidence based treatment guidelines. The Hungarian Pancreatic Study Group proposed to prepare an evidence based guideline based on the available international guidelines and evidence. The preparatory and consultation task force appointed by the Hungarian Pancreatic Study Group translated and complemented and/or modified the international guidelines if it was necessary. 123 relevant clinical questions in 11 topics were defined. Evidence was classified according to the UpToDate® grading system. The draft of the guidelines were presented and discussed at the consensus meeting in September 12, 2014. All clinical questions were accepted with total or strong agreement. The present guideline is the first evidence based guideline for chronic pancreatitis in Hungary. This guideline provides very important and helpful data for tuition, everyday practice and proper financing of chronic pancreatitis. Therefore, the authors believe that these guidelines will widely become a basic reference in Hungary.

Chymotrypsin C is a co-activator of human pancreatic procarboxypeptidases A1 and A2.

Human digestive carboxypeptidases CPA1, CPA2, and CPB1 are secreted by the pancreas as inactive proenzymes containing a 94-96-amino acid-long propeptide. Activation of procarboxypeptidases is initiated by proteolytic cleavage at the C-terminal end of the propeptide by trypsin. Here, we demonstrate that subsequent cleavage of the propeptide by chymotrypsin C (CTRC) induces a nearly 10-fold increase in the activity of trypsin-activated CPA1 and CPA2, whereas CPB1 activity is unaffected. Other human pancreatic proteases such as chymotrypsin B1, chymotrypsin B2, chymotrypsin-like enzyme-1, elastase 2A, elastase 3A, or elastase 3B are inactive or markedly less effective at promoting procarboxypeptidase activation. On the basis of these observations, we propose that CTRC is a physiological co-activator of proCPA1 and proCPA2. Furthermore, the results confirm and extend the notion that CTRC is a key regulator of digestive zymogen activation.

Uncertainties in the classification of human cationic trypsinogen (PRSS1) variants as hereditary pancreatitis-associated mutations.

BACKGROUND: Autosomal dominant hereditary pancreatitis has been conclusively linked with cationic trypsinogen (PRSS1) mutations p.R122H and p.N29I, which can be found in approximately 90% of mutation-positive cases. To date, 35 additional rare or private PRSS1 variants have been identified in subjects with hereditary or sporadic, idiopathic chronic pancreatitis. Despite the lack of sufficient genetic and functional evidence, many of these rare variants have been labelled as pancreatitis associated. This problematic trend is notably illustrated by two recent studies that classified the p.A121T PRSS1 variant as pancreatitis associated, in large part owing to its intimate proximity to arginine-122, the residue affected by the disease causing p.R122H mutation. METHODS AND RESULTS: Here we demonstrate that the p.A121T variant is functionally innocuous and shows no verifiable association with hereditary pancreatitis, on the basis of the available inconclusive data. CONCLUSION: This case cautions that assignment of clinical relevance to rare PRSS1 variants should not be based on a perceived analogy with genuine disease causing PRSS1 mutations, and further studies are required to prove or rule out possible low penetrance causality of rare PRSS1 variants.

[Clinical importance of pancreas divisum]. / A pancreas divisum klinikai jelentosége.

Pancreas divisum, the most common congenital pancreatic anomaly, is associated with three main duct abnormalities: type I, with total failure of fusion; type II, with dorsal duct dominant drainage; and type III, incomplete divisum where a small communication branch is present. Three clinical conditions are associated with pancreas divisum: (1) acute recurrent pancreatitis; (2) chronic pancreatitis with the chronic inflammation in the dorsal bed; (3) abdominal "pancreatic-type" obstructive pain. Endoscopic retrograde cholangiopancreatography is the primary method for diagnosing pancreas divisum, but magnetic resonance cholangiopancreatography is becoming a first choice for non-invasive evaluation. Pancreas divisum per se does not require medical intervention. Patients who experience mild episodic acute pancreatitis should be managed medically. Surgical or endoscopic interventions relieve the obstruction by improving dorsal duct drainage via the minor papilla.

Pancreatitis-associated chymotrypsinogen C (CTRC) mutant elicits endoplasmic reticulum stress in pancreatic acinar cells.

OBJECTIVE: Chronic pancreatitis is a progressive inflammatory disorder of the pancreas characterised by permanent destruction of acinar cells. Mutations in the chymotrypsinogen C (CTRC) gene have been linked to the development of chronic pancreatitis. The aim of the present study was to explore whether CTRC mutants induce endoplasmic reticulum (ER) stress in pancreatic acinar cells. DESIGN: Dexamethasone-differentiated AR42J rat acinar cells and freshly isolated mouse acini were transfected with recombinant adenovirus carrying wild-type CTRC or the p.A73T pancreatitis-associated mutant. ER stress markers were assessed by reverse transcription-PCR and western blotting. Apoptosis was characterised by caspase-3/7 activity and the TUNEL assay. RESULTS: Acinar cells transfected with the p.A73T mutant, but not those with wild-type CTRC, developed significant ER stress as judged by elevated mRNA and protein levels of the ER chaperone immunoglobulin-binding protein (BiP), increased splicing of the X-box binding protein-1 (XBP1) mRNA and marked induction of the transcription factor C/EBP-homologous protein (CHOP), a mediator of ER stress-associated apoptosis. Consistent with higher CHOP expression, AR42J cells expressing the p.A73T mutant became detached over time and showed considerably increased caspase-3/7 activity and TUNEL staining. CONCLUSIONS: Pancreatitis-associated CTRC mutations can markedly increase the propensity of chymotrypsinogen C to elicit ER stress in pancreatic acinar cells. Thus, carriers of CTRC mutations may be at a higher risk of developing ER stress in the exocrine pancreas, which may contribute to parenchymal damage through acinar cell apoptosis.

Complete analysis of the human mesotrypsinogen gene (PRSS3) in patients with chronic pancreatitis.

BACKGROUND/AIMS: A sustained imbalance of pancreatic proteases and their inhibitors seems to be important for the development of chronic pancreatitis (CP). Mesotrypsin (PRSS3) can degrade intrapancreatic trypsin inhibitors that protect against CP. Genetic variants that cause higher mesotrypsin activity might increase the risk for CP. METHODS: We analyzed all 5 exons and the adjacent non-coding sequences of PRSS3 by direct sequencing of 313 CP patients and 327 controls. Additionally, exon 4 was investigated in 855 patients and 1,294 controls and a c.454+191G>A variant in 855 patients and 1,467 controls. The c.499A>G (p.T167A) variant was analyzed functionally using transiently transfected HEK 293T cells. RESULTS: In the exonic regions, the previously described common c.94_96delGAG (p.E32del) variant and a novel p.T167A non-synonymous alteration were identified. Extended analysis of the p.T167A variant revealed no association to CP and in functional assays p.T167A showed normal secretion and activity. Variants of the intronic regions, including the extensively analyzed c.454+191G>A alteration, were not associated with the disease. Haplotype reconstruction using variants with a minor allele frequency of >1% revealed no CP-associated haplotype. CONCLUSIONS: Although the trypsin inhibitor-degrading activity qualified PRSS3 as a candidate for a novel CP susceptibility gene, we found no association between a specific variant or haplotype and CP in our cohort with a high suspicion of genetically determined disease.

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.

Hereditary pancreatitis caused by mutation-induced misfolding of human cationic trypsinogen: a novel disease mechanism.

We investigated the biochemical properties and cellular expression of the c.346C>T (p.R116C) human cationic trypsinogen (PRSS1) mutant, which we identified in a German family with autosomal dominant hereditary pancreatitis. This mutation leads to an unpaired Cys residue with the potential to interfere with protein folding via incorrect disulfide bond formation. Recombinantly expressed p.R116C trypsinogen exhibited a tendency for misfolding in vitro. Biochemical analysis of the correctly folded, purified p.R116C mutant revealed unchanged activation and degradation characteristics compared to wild type trypsinogen. Secretion of mutant p.R116C from transfected 293T cells was reduced to approximately 20% of wild type. A similar secretion defect was observed with another rare PRSS1 variant, p.C139S, whereas mutants p.A16V, p.N29I, p.N29T, p.E79K, p.R122C, and p.R122H were secreted normally. All mutants were detected in cell extracts at comparable levels but a large portion of mutant p.R116C was present in an insoluble, protease-sensitive form. Consistent with intracellular retention of misfolded trypsinogen, the endoplasmic reticulum (ER) stress markers immunoglobulin-binding protein (BiP) and the spliced form of the X-box binding protein-1 (XBP1s) were elevated in cells expressing mutant p.R116C. The results indicate that mutation-induced misfolding and intracellular retention of human cationic trypsinogen causes hereditary pancreatitis in carriers of the p.R116C mutation. ER stress triggered by trypsinogen misfolding represents a new potential disease mechanism for chronic pancreatitis.

Chronic pancreatitis: Multicentre prospective data collection and analysis by the Hungarian Pancreatic Study Group.

INTRODUCTION: Chronic pancreatitis is an inflammatory disease associated with structural and functional damage to the pancreas, causing pain, maldigestion and weight loss and thus worsening the quality of life. AIMS AND METHODS: Our aim was to find correlations from a multicentre database representing the epidemiological traits, diagnosis and treatment of the disease in Hungary. The Hungarian Pancreatic Study Group collected data prospectively from 2012 to 2014 on patients suffering from chronic pancreatitis. Statistical analysis was performed on different questions. RESULTS: Data on 229 patients (74% male and 26% female) were uploaded from 14 centres. Daily alcohol consumption was present in the aetiology of 56% of the patients. 66% of the patients were previously treated for acute exacerbation. One third of the patients had had previous endoscopic or surgical interventions. Pain was present in 69% of the cases, endocrine insufficiency in 33%, diarrhoea in 13% and weight loss in 39%. Diagnosis was confirmed with US (80%), CT scan (52%), MRI-MRCP (6%), ERCP (39%), and EUS (7,4%). A functional test was carried out in 5% of the patients. In 31% of the cases, an endoscopic intervention was performed with the need for re-intervention in 5%. Further elective surgical intervention was necessitated in 44% of endoscopies. 20% of the registered patients were primarily treated with surgery. The biliary complication rate for surgery was significantly smaller (2%) than endoscopy (27%); however, pancreatic complications were higher in the patients treated with surgery. Patients who smoked regularly needed significantly more surgical intervention following endoscopy (66.7% vs. 26.9%, p = 0.002) than non-smokers, and the ratio of surgical intervention alone was also significantly higher (27.3% vs. 10.8%, p = 0.004). The ratio of surgery in patients who smoked and drank was significantly higher (30.09% vs. 12.5%, p = 0.012) than in abstinent and non-smoking patients, similarly to the need for further surgical intervention after endoscopic treatment (71.43% vs. 27.78%, p = 0.004). CONCLUSIONS: According to the data analysed, the epidemiological data and the aetiological factors in our cohort differ little from European trends. The study highlighted the overuse of ERCP as a diagnostic modality and the low ratio of use of endoscopic ultrasonography. The results proved that alcohol consumption and smoking represent risk factors for the increased need for surgical intervention. Chronic pancreatitis should be treated by multidisciplinary consensus grounded in evidence-based medicine.

Pancreatic Cancer: Multicenter Prospective Data Collection and Analysis by the Hungarian Pancreatic Study Group.

BACKGROUND AND AIMS: Pancreatic cancer is a devastating disease with poor prognosis. There is very limited information available regarding the epidemiology and treatment strategies of pancreatic cancer in Central Europe. The purpose of the study was to prospectively collect and analyze data of pancreatic cancer in the Hungarian population. METHODS: The Hungarian Pancreatic Study Group (HPSG) organized prospective, uniform data collection. Altogether 354 patients were enrolled from 14 Hungarian centers. RESULTS: Chronic pancreatitis was present in 3.7% of the cases, while 33.7% of the patients had diabetes. Family history for pancreatic cancer was positive in 4.8%. The most frequent presenting symptoms included pain (63.8%), weight loss (63%) and jaundice (52.5%). The reported frequency of smoking and alcohol consumption was lower than expected (28.5% and 27.4%, respectively). The majority of patients (75.6%) were diagnosed with advanced disease. Most patients (83.6%) had a primary tumor located in the pancreatic head. The histological diagnosis was ductal adenocarcinoma in 90.7% of the cases, while neuroendocrine tumor was present in 5.3%. Biliary stent implantation was performed in 166 patients, 59.2% of them received metal stents. Primary tumor resection was performed in 60 (16.9%) patients. Enteral or biliary bypass was done in 35 and 49 patients, respectively. In a multivariate Cox-regression model, smoking status and presence of gemcitabine-based chemotherapy were identified as independent predictors for overall survival. CONCLUSION: We report the first data from a large cohort of Hungarian pancreatic cancer patients. We identified smoking status and chemotherapy as independent predictors in this cohort.

Variants in CPA1 are strongly associated with early onset chronic pancreatitis.

Chronic pancreatitis is an inflammatory disorder of the pancreas. We analyzed CPA1, encoding carboxypeptidase A1, in subjects with nonalcoholic chronic pancreatitis (cases) and controls in a German discovery set and three replication sets. Functionally impaired variants were present in 29/944 (3.1%) German cases and 5/3,938 (0.1%) controls (odds ratio (OR) = 24.9, P = 1.5 × 10(-16)). The association was strongest in subjects aged ≤ 10 years (9.7%; OR = 84.0, P = 4.1 × 10(-24)). In the replication sets, defective CPA1 variants were present in 8/600 (1.3%) cases and 9/2,432 (0.4%) controls from Europe (P = 0.01), 5/230 (2.2%) cases and 0/264 controls from India (P = 0.02) and 5/247 (2.0%) cases and 0/341 controls from Japan (P = 0.013). The mechanism by which CPA1 variants confer increased pancreatitis risk may involve misfolding-induced endoplasmic reticulum stress rather than elevated trypsin activity, as is seen with other genetic risk factors for this disease.

Tropical calcific pancreatitis and its association with CTRC and SPINK1 (p.N34S) variants.

BACKGROUND: Tropical calcific pancreatitis (TCP) is a relatively common form of chronic pancreatitis in parts of Asia and Africa. The SPINK1 variant p.N34S is strongly associated with TCP, but other genetic factors remain to be defined. Chymotrypsinogen C (CTRC) degrades trypsinogen and loss-of-function variants have been found in European patients with chronic pancreatitis. Preliminary data indicate that CTRC might increase the risk for TCP. MATERIALS AND METHODS: We selected 150 Indian TCP patients and 150 Indian controls to perform mutational screening of the complete coding region of CTRC and exon 3 of SPINK1. We performed in-silico analysis and functional studies of novel CTRC variants. RESULTS: We identified eight variants among this sample. Three were synonymous and c.180 C>T was significantly enriched in patients (odds ratio=2.09; 95% confidence interval=1.19-3.67; P=0.03). We identified a novel nonsynonymous CTRC (p.G61R) variant in one of 146 patients (0.7%), but absent from controls. In-silico analysis showed that this variant affected a conserved residue, and functional analysis showed that p.G61R results in a complete loss of CTRC secretion from transiently transfected human embryonic kidney 293T cells. SPINK1 p.N34S was present in 31.8% of patients compared with 4.7% in controls, there was no significant cosegregation with CTRC variants. CONCLUSION: The contribution of CTRC variants to TCP is relatively small, but the identification of novel loss-of-function variants (p.G61R) underscores the importance of the trypsinogen pathway in causing TCP.

Chymotrypsin C (CTRC) variants that diminish activity or secretion are associated with chronic pancreatitis.

Chronic pancreatitis is a persistent inflammatory disease of the pancreas, in which the digestive protease trypsin has a fundamental pathogenetic role. Here we have analyzed the gene encoding the trypsin-degrading enzyme chymotrypsin C (CTRC) in German subjects with idiopathic or hereditary chronic pancreatitis. Two alterations in this gene, p.R254W and p.K247_R254del, were significantly overrepresented in the pancreatitis group, being present in 30 of 901 (3.3%) affected individuals but only 21 of 2,804 (0.7%) controls (odds ratio (OR) = 4.6; confidence interval (CI) = 2.6-8.0; P = 1.3 x 10(-7)). A replication study identified these two variants in 10 of 348 (2.9%) individuals with alcoholic chronic pancreatitis but only 3 of 432 (0.7%) subjects with alcoholic liver disease (OR = 4.2; CI = 1.2-15.5; P = 0.02). CTRC variants were also found in 10 of 71 (14.1%) Indian subjects with tropical pancreatitis but only 1 of 84 (1.2%) healthy controls (OR = 13.6; CI = 1.7-109.2; P = 0.0028). Functional analysis of the CTRC variants showed impaired activity and/or reduced secretion. The results indicate that loss-of-function alterations in CTRC predispose to pancreatitis by diminishing its protective trypsin-degrading activity.

Chymotrypsin C (caldecrin) promotes degradation of human cationic trypsin: identity with Rinderknecht's enzyme Y.

Digestive trypsins undergo proteolytic breakdown during their transit in the human alimentary tract, which has been assumed to occur through trypsin-mediated cleavages, termed autolysis. Autolysis was also postulated to play a protective role against pancreatitis by eliminating prematurely activated intrapancreatic trypsin. However, autolysis of human cationic trypsin is very slow in vitro, which is inconsistent with the documented intestinal trypsin degradation or a putative protective role. Here we report that degradation of human cationic trypsin is triggered by chymotrypsin C, which selectively cleaves the Leu(81)-Glu(82) peptide bond within the Ca(2+) binding loop. Further degradation and inactivation of cationic trypsin is then achieved through tryptic cleavage of the Arg(122)-Val(123) peptide bond. Consequently, mutation of either Leu(81) or Arg(122) blocks chymotrypsin C-mediated trypsin degradation. Calcium affords protection against chymotrypsin C-mediated cleavage, with complete stabilization observed at 1 mM concentration. Chymotrypsin C is highly specific in promoting trypsin degradation, because chymotrypsin B1, chymotrypsin B2, elastase 2A, elastase 3A, or elastase 3B are ineffective. Chymotrypsin C also rapidly degrades all three human trypsinogen isoforms and appears identical to enzyme Y, the enigmatic trypsinogen-degrading activity described by Heinrich Rinderknecht in 1988. Taken together with previous observations, the results identify chymotrypsin C as a key regulator of activation and degradation of cationic trypsin. Thus, in the high Ca(2+) environment of the duodenum, chymotrypsin C facilitates trypsinogen activation, whereas in the lower intestines, chymotrypsin C promotes trypsin degradation as a function of decreasing luminal Ca(2+) concentrations.