Substrate specificity of human chymotrypsin-like protease (CTRL) characterized by phage display-selected small-protein inhibitors

Chymotrypsin-like protease (CTRL) is one of the four chymotrypsin isoforms expressed in the human exocrine pancreas. Human genetic and experimental evidence indicate that chymotrypsins B1, B2, and C (CTRB1, CTRB2 and CTRC) are important not only for protein digestion but also for protecting the pancreas against pancreatitis by degrading potentially harmful trypsinogen. CTRL has not been reported to play a similar role, possibly due to its low abundance and/or different substrate specificity. To address this problem, we investigated the specificity of the substrate-binding groove of CTRL by evolving the substrate-like canonical loop of the Schistocerca gregaria proteinase inhibitor 2 (SGPI-2), a small-protein reversible chymotrypsin inhibitor to bind CTRL. We found that phage-associated SGPI-2 variants with strong affinity to CTRL were similar to those evolved previously against CTRB1, CTRB2 or bovine chymotrypsin A (bCTRA), indicating comparable substrate specificity. When tested as recombinant proteins, SGPI-2 variants inhibited CTRL with similar or slightly weaker affinity than bCTRA, confirming that CTRL is a typical chymotrypsin. Interestingly, an SGPI-2 variant selected with a Thr29His mutation in its reactive loop was found to inhibit CTRL strongly, but it was digested rapidly by bCTRA. Finally, CTRL was shown to degrade human anionic trypsinogen, however, at a much slower rate than CTRB2, suggesting that CTRL may not have a significant role in the pancreatic defense mechanisms against inappropriate trypsinogen activation and pancreatitis.

Risk of chronic pancreatitis in carriers of the c.180C>T (p.Gly60=) CTRC variant: case-control studies and meta-analysis

Chymotrypsin C (CTRC) is a digestive serine protease produced by the pancreas that regulates intrapancreatic trypsin activity and provides a defensive mechanism against chronic pancreatitis (CP). CTRC exerts its protective effect by promoting degradation of trypsinogen, the precursor to trypsin. Loss-of-function missense and microdeletion variants of CTRC are found in around 4% of CP cases and increase disease risk by approximately 3-7-fold. In addition, a commonly occurring synonymous CTRC variant c.180C>T (p.Gly60=) was reported to increase CP risk in various cohorts but a global analysis of its impact has been lacking. Here, we analyzed the frequency and effect size of variant c.180C>T in Hungarian and pan-European cohorts, and performed meta-analysis of the new and published genetic association data. When allele frequency was considered, meta-analysis revealed an overall frequency of 14.2% in patients and 8.7% in controls (allelic odds ratio (OR) 2.18, 95% confidence interval (CI) 1.72-2.75). When genotypes were examined, c.180TT homozygosity was observed in 3.9% of CP patients and in 1.2% of controls, and c.180CT heterozygosity was present in 22.9% of CP patients and in 15.5% of controls. Relative to the c.180CC genotype, the genotypic OR values were 5.29 (95% CI 2.63-10.64), and 1.94 (95% CI 1.57-2.38), respectively, indicating stronger CP risk in homozygous carriers. Finally, we obtained preliminary evidence that the variant is associated with reduced CTRC mRNA levels in the pancreas. Taken together, the results indicate that CTRC variant c.180C>T is a clinically relevant risk factor, and should be considered when genetic etiology of CP is investigated.

Arg236 in human chymotrypsin B2 (CTRB2) is a key determinant of high enzyme activity, trypsinogen degradation capacity, and protection against pancreatitis

Pancreatic chymotrypsins (CTRs) are digestive proteases that in humans include CTRB1, CTRB2, CTRC, and CTRL. The highly similar CTRB1 and CTRB2 are the products of gene duplication. A common inversion at the CTRB1-CTRB2 locus reverses the expression ratio of these isoforms in favor of CTRB2. Carriers of the inversion allele are protected against the inflammatory disorder pancreatitis presumably via their increased capacity for CTRB2-mediated degradation of harmful trypsinogen. To reveal the protective molecular determinants of CTRB2, we compared enzymatic properties of CTRB1, CTRB2, and bovine CTRA (bCTRA). By evolving substrate-like Schistocerca gregaria proteinase inhibitor 2 (SGPI-2) inhibitory loop variants against the chymotrypsins, we found that the substrate binding groove of the three enzymes had overlapping specificities. Based on the selected sequences, we produced eight SGPI-2 variants. Remarkably, CTRB2 and bCTRA bound these inhibitors with significantly higher affinity than CTRB1. Moreover, digestion of peptide substrates, beta casein, and human anionic trypsinogen unequivocally confirmed that CTRB2 is a generally better enzyme than CTRB1 while the potency of bCTRA lies between those of the human isoforms. Unexpectedly, mutation D236R alone converted CTRB1 to a CTRB2-like high activity protease. Modeling indicated that in CTRB1 Met210 partially obstructed the substrate binding groove, which was relieved by the D236R mutation. Taken together, we identify CTRB2 Arg236 as a key positive determinant, while CTRB1 Asp236 as a negative determinant for chymotrypsin activity. These findings strongly support the concept that in carriers of the CTRB1-CTRB2 inversion allele, the superior trypsinogen degradation capacity of CTRB2 protects against pancreatitis.

Loss-of-function variant in chymotrypsin like elastase 3B (CELA3B) is associated with non-alcoholic chronic pancreatitis

BACKGROUND

Genetic alterations in digestive enzymes have been associated with chronic pancreatitis (CP). Recently, chymotrypsin like elastase 3B (CELA3B) emerged as a novel risk gene. Thus, we evaluated CELA3B in two European cohorts with CP.

METHODS

We analyzed all 8 CELA3B exons in 550 German non-alcoholic CP (NACP) patients and in 241 German controls by targeted DNA sequencing. In addition, we analyzed exons 6 and 7 by Sanger sequencing and the c.129+1G>A variant by melting curve analysis in 1078 further German controls. As replication cohort, we investigated up to 243 non-German European NACP patients and up to 1665 controls originating from Poland, Hungary, and Sweden. We assessed the cellular secretion and the elastase activity of recombinant CELA3B variants.

RESULTS

In the German discovery cohort, we detected a splice-site variant in intron 2, c.129+1G>A, in 9/550 (1.64%) CP patients and in 5/1319 (0.38%) controls (P=0.007, OR=4.4, 95% CI=1.5-13.0). In the European replication cohort, this variant was also enriched in patients (9/178 [5.06%]) versus controls (13/1247 [1.04%]) (P=0.001, OR=5.1, 95% CI=2.1-12.0). We did not find the two previously reported codon 90 variants, p.R90C and p.R90L.

CONCLUSIONS

Our data indicate that CELA3B is a susceptibility gene for CP. In contrast to previous reports suggesting that increased CELA3B activity is associated with CP risk, the splice-site variant identified here is predicted to cause diminished CELA3B expression. How reduced CELA3B function predisposes to pancreatitis remains to be elucidated.

Variants in the pancreatic CUB and zona pellucida-like domains 1 (CUZD1) gene in early-onset chronic pancreatitis - A possible new susceptibility gene

OBJECTIVE

Non-alcoholic chronic pancreatitis (NACP) frequently develops in the setting of genetic susceptibility associated with alterations in genes that are highly expressed in the pancreas. However, the genetic basis of NACP remains unresolved in a significant number of patients warranting a search for further risk genes.

DESIGN

We analyzed CUZD1, which encodes the CUB and zona pellucida-like domains 1 protein that is found in high levels in pancreatic acinar cells. We sequenced the coding region in 1163 European patients and 2018 European controls. In addition, we analyzed 297 patients and 1070 controls from Japan. We analyzed secretion of wild-type and mutant CUZD1 from transfected cells using Western blotting.

RESULTS

In the European cohort, we detected 30 non-synonymous variants. Using different prediction tools (SIFT, CADD, PROVEAN, PredictSNP) or the combination of these tools, we found accumulation of predicted deleterious variants in patients (p-value range 0.002-0.013; OR range 3.1-5.2). No association was found in the Japanese cohort, in which 13 non-synonymous variants were detected. Functional studies revealed >50% reduced secretion of 7 variants, however, these variants were not significantly enriched in European CP patients.

CONCLUSION

Our data indicate that CUZD1 might be a novel susceptibility gene for NACP. How these variants predispose to pancreatitis remains to be elucidated.

Common calcium-sensing receptor (CASR) gene variants do not modify risk for chronic pancreatitis in a Hungarian cohort

The calcium-sensing receptor (CASR) is expressed in the pancreas where it might regulate calcium concentrations in pancreatic secretions. Two independent studies reported conflicting results claiming that commonly occurring missense variants of the CASR gene are risk factors for chronic pancreatitis (CP). Here, we attempted to replicate the association between CASR variants and CP. We analyzed 337 patients and 840 controls from the Hungarian National Pancreas Registry either by direct sequencing of exon 7 and the flanking noncoding regions or by TaqMan SNP genotyping assays. We identified two common missense variants, c.2956G>T (p.A986S), and c.2968A>G (p.R990G), three low-frequency variants, c.3031C>G (p.Q1011E), c.2610G>A (p.E870=) and c.∗60T>A, and 8 rare variants including the novel variant c.1895G>A (p.G632D). When allelic or genotype distributions were considered, none of the CASR variants associated with CP. Subgroup analysis of nonalcoholic versus alcoholic patients revealed no disease association either. Our results demonstrate that common CASR variants do not modify the risk for CP and should not be considered as genetic risk factors in the clinical setting.

Oral Proton Pump Inhibitors May Be as Effective as Intravenous in Peptic Ulcer Bleeding: A Systematic Review and Meta-analysis

INTRODUCTION

Current guidelines recommend intravenous (IV) proton pump inhibitor (PPI) therapy in peptic ulcer bleeding (PUB). We aimed to compare the efficacy of oral and IV administration of PPIs in PUB.

METHODS

We performed a systematic search in 4 databases for randomized controlled trials, which compared the outcomes of oral PPI therapy with IV PPI therapy for PUB. The primary outcomes were 30-day recurrent bleeding and 30-day mortality. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for dichotomous outcomes, while weighted mean differences (WMDs) with CI were calculated for continuous outcomes in meta-analysis. The protocol was registered a priori onto PROSPERO (CRD42020155852).

RESULTS

A total of 14 randomized controlled trials reported 1,951 peptic ulcer patients, 977 and 974 of which were in the control and intervention groups, respectively. There were no statistically significant differences between oral and IV administration regarding 30-day rebleeding rate (OR = 0.96, CI: 0.65-1.44); 30-day mortality (OR = 0.70, CI: 0.35-1.40); length of hospital stay (WMD = -0.25, CI: -0.93 to -0.42); transfusion requirements (WMD = -0.09, CI: -0.07 to 0.24); need for surgery (OR = 0.91, CI: 0.40-2.07); further endoscopic therapy (OR = 1.04, CI: 0.56-1.93); and need for re-endoscopy (OR = 0.81, CI: 0.52-1.28). Heterogeneity was negligible in all analysis, except for the analysis on the length of hospitalization (I2 = 82.3%, P = 0.001).

DISCUSSION

Recent evidence suggests that the oral administration of PPI is not inferior to the IV PPI treatment in PUB after endoscopic management, but further studies are warranted.

Personalised health education against health damage of COVID-19 epidemic in the elderly Hungarian population (PROACTIVE-19): protocol of an adaptive randomised controlled clinical trial

BACKGROUND

Early reports indicate that COVID-19 may require intensive care unit (ICU) admission in 5-26% and overall mortality can rise to 11% of the recognised cases, particularly affecting the elderly. There is a lack of evidence-based targeted pharmacological therapy for its prevention and treatment. We aim to compare the effects of a World Health Organization recommendation-based education and a personalised complex preventive lifestyle intervention package (based on the same WHO recommendation) on the outcomes of the COVID-19.

METHODS

PROACTIVE-19 is a pragmatic, randomised controlled clinical trial with adaptive "sample size re-estimation" design. Hungarian population over the age of 60 years without confirmed COVID-19 will be approached to participate in a telephone health assessment and lifestyle counselling voluntarily. Volunteers will be randomised into two groups: (A) general health education and (B) personalised health education. Participants will go through questioning and recommendation in 5 fields: (1) mental health, (2) smoking habits, (3) physical activity, (4) dietary habits, and (5) alcohol consumption. Both groups A and B will receive the same line of questioning to assess habits concerning these topics. Assessment will be done weekly during the first month, every second week in the second month, then monthly. The composite primary endpoint will include the rate of ICU admission, hospital admission (longer than 48 h), and mortality in COVID-19-positive cases. The estimated sample size is 3788 subjects per study arm. The planned duration of the follow-up is a minimum of 1 year.

DISCUSSION

These interventions may boost the body's cardiovascular and pulmonary reserve capacities, leading to improved resistance against the damage caused by COVID-19. Consequently, lifestyle changes can reduce the incidence of life-threatening conditions and attenuate the detrimental effects of the pandemic seriously affecting the older population.

TRIAL REGISTRATION

The study has been approved by the Scientific and Research Ethics Committee of the Hungarian Medical Research Council (IV/2428- 2 /2020/EKU) and has been registered at clinicaltrials.gov ( NCT04321928 ) on 25 March 2020.

Chronic pancreatitis with polycystic kidney disease: A rare coincidence?

INTRODUCTION

In children, chronic pancreatitis (CP) is usually associated with anatomical anomalies of the pancreas and biliary tract or is genetically determined. Autosomal dominant polycystic kidney disease (ADPKD) may present with extrarenal cyst formation, sometimes involving the pancreas. Large enough, these cysts may cause pancreatitis in ADPKD patients.

CASE PRESENTATION

Herein, we present a case of a 12-year-old Caucasian girl with recurrent pancreatitis with no identifiable traumatic, metabolic, infectious, drug, or immunologic causes. Structural anomalies of the pancreas, including cysts, were ruled out by imaging. However, bilateral cystic kidneys were found as an incidental finding. Her family history was negative for pancreatitis, but positive for polycystic kidney disease. Molecular analysis of ADPKD-causing mutations revealed a novel c.9659C>A (p.Ser3220*) mutation in the PKD1 gene confirming the clinical suspicion of ADPKD. Although CP may rarely occur as an extrarenal manifestation of ADPKD with pancreatic cysts, it is unusual in their absence. Thus, molecular analysis of pancreatitis susceptibility genes was performed and a homozygous pathologic c.180C>T (p.G60=) variant of the CTRC gene, known to increase the risk of CP, was confirmed.

CONCLUSION

This is the first reported case of a pediatric patient with coincidence of genetically determined CP and ADPKD. Occurrence of pancreatitis in children with ADPKD without pancreatic cysts warrants further investigation of CP causing mutations.

Observational longitudinal multicentre investigation of acute pancreatitis (GOULASH PLUS): follow-up of the GOULASH study, protocol

BACKGROUND

Acute pancreatitis (AP) is an inflammatory condition that can lead to late consequences. Recurrent AP (RAP) develops in 20% of patients and chronic pancreatitis (CP) occurs in 7%-12.8%. However, we do not have sufficient information to establish an evidence-based statement to define early CP, or how to prevent its development.

AIM

The aim of this study was to understand the influencing factors and to determine which parameters should be measured or used as a biomarker to detect the early phase of CP.

METHODS/DESIGN

This is an observational prospective follow-up study of the GOULASH-trial (ISRTCN 63827758) in which (1) all severity of pancreatitis are included; (2) patients receive only therapeutic modalities which are accepted by the evidence based medicine (EBM) guideline; (3) whole blood, serum and plasma samples are stored in our biobank; and (4) large amount of variables are collected and kept in our electronic database including anamnestic data, physical examination, laboratory parameters, imaging, therapy and complications. Therefore, this fully characterised patient cohort are well suitable for this longitudinal follow-up study. Patients' selection: patients enrolled in the GOULASH study will be offered to join to the longitudinal study. The follow-up will be at 1, 2, 3, 4, 5 and 6 years after the episode of AP. Anamnestic data will be collected by questionnaires: (1) diet history questionnaire, (2) 36-Item Short-Form Health Survey, (3) physical activity questionnaire and (4) stress questionnaire. Genetic tests will be performed for the genes associated with CP. The exocrine and endocrine pancreatic, liver and kidney functions will be determined by laboratory tests, stool sample analyses and imaging. Cost-effectiveness will be analysed to examine the relationship between events of interest and health-related quality of life or to explore subgroup differences.

CONCLUSION

This study will provide information about the risk and influencing factors leading to CP and identify the most useful measurable parameters.

TRIAL REGISTRATION NUMBER

ISRCTN63396106.

Natural single-nucleotide deletion in chymotrypsinogen C gene increases severity of secretagogue-induced pancreatitis in C57BL/6 mice

Genetic susceptibility to chronic pancreatitis in humans is frequently associated with mutations that increase activation of the digestive protease trypsin. Intrapancreatic trypsin activation is an early event in experimental acute pancreatitis in rodents, suggesting that trypsin is a key driver of pathology. In contrast to trypsin, the pancreatic protease chymotrypsin serves a protective function by mitigating trypsin activation through degradation. In humans, loss-of-function mutations in chymotrypsin C (CTRC) are common risk factors for chronic pancreatitis; however, the pathogenic effect of CTRC deficiency has not been corroborated in animal models yet. Here we report that C57BL/6 mice that are widely used for genetic manipulations do not express functional CTRC due to a single-nucleotide deletion in exon 2 of the Ctrc gene. We restored a functional Ctrc locus in C57BL/6N mice and demonstrated that in the novel Ctrc+ strain the severity of cerulein-induced experimental acute and chronic pancreatitis was significantly ameliorated. Improved disease parameters were associated with reduced intrapancreatic trypsin activation suggesting a causal link between CTRC-mediated trypsinogen degradation and protection against pancreatitis. Taken together with prior human genetic and biochemical studies, the observations provide conclusive evidence for the protective role of CTRC against pancreatitis.

Genetics, Cell Biology, and Pathophysiology of Pancreatitis

Since the discovery of the first trypsinogen mutation in families with hereditary pancreatitis, pancreatic genetics has made rapid progress. The identification of mutations in genes involved in the digestive protease-antiprotease pathway has lent additional support to the notion that pancreatitis is a disease of autodigestion. Clinical and experimental observations have provided compelling evidence that premature intrapancreatic activation of digestive proteases is critical in pancreatitis onset. However, disease course and severity are mostly governed by inflammatory cells that drive local and systemic immune responses. In this article, we review the genetics, cell biology, and immunology of pancreatitis with a focus on protease activation pathways and other early events.

Human CPA1 mutation causes digestive enzyme misfolding and chronic pancreatitis in mice

OBJECTIVE

Chronic pancreatitis is a progressive, relapsing inflammatory disorder of the pancreas, which often develops in the background of genetic susceptibility. Recently, loss-of-function mutations in CPA1, which encodes the digestive enzyme carboxypeptidase A1, were described in sporadic early onset cases and in hereditary pancreatitis. Mutation-induced misfolding of CPA1 and associated endoplasmic reticulum (ER) stress was suggested as potential disease mechanism; however, in vivo evidence has been lacking. The objective of the present study was to create a mouse model that recapitulates features of CPA1-associated chronic pancreatitis.

DESIGN

We knocked-in the most frequently occurring p.N256K human CPA1 mutation to the mouse Cpa1 locus. Mutant mice were characterised with respect to pancreas pathology and ER stress and compared with C57BL/6N and CPA1 null control mice.

RESULTS

In the CPA1 N256K mutant mice, we observed hallmarks of chronic pancreatitis that included progressive acinar cell atrophy, inflammatory cell infiltration, fibrosis and acinar-ductal metaplasia. In contrast, similarly to the C57BL/6N mice, the CPA1 null control strain exhibited no signs of pancreatic disease. Mutation p.N256K induced misfolding of mouse CPA1 and resulted in elevated expression of ER stress markers Hspa5 (BiP) and Ddit3 (CHOP) both in cell culture and mutant mice.

CONCLUSION

The results offer categorical evidence that CPA1 mutations elicit enzyme misfolding and cause chronic pancreatitis via an ER stress-related mechanism.

Chymotrypsin Reduces the Severity of Secretagogue-Induced Pancreatitis in Mice

Intrapancreatic activation of the digestive proteases trypsin and chymotrypsin is an early event in the development of pancreatitis. Human genetic studies indicate that chymotrypsin controls trypsin activity via degradation, but there is no evidence of this from animal models. We used CRISPR-Cas9 to disrupt the chymotrypsinogen B1 gene (Ctrb1) in C57BL/6N mice and induced pancreatitis in CTRB1-deficient and C57BL/6N (control) mice by administration of cerulein. CTRB1-deficient mice given cerulein had significant increases in intrapancreatic trypsin activity and developed more severe pancreatitis compared with control mice. CTRB1 therefore protects against secretagogue-induced pancreatitis by reducing trypsin activity. Protease inhibitors developed for treatment of pancreatitis should be designed to target trypsin but not chymotrypsin.

Genome-wide association study identifies inversion in the CTRB1-CTRB2 locus to modify risk for alcoholic and non-alcoholic chronic pancreatitis

OBJECTIVE

Alcohol-related pancreatitis is associated with a disproportionately large number of hospitalisations among GI disorders. Despite its clinical importance, genetic susceptibility to alcoholic chronic pancreatitis (CP) is poorly characterised. To identify risk genes for alcoholic CP and to evaluate their relevance in non-alcoholic CP, we performed a genome-wide association study and functional characterisation of a new pancreatitis locus.

DESIGN

1959 European alcoholic CP patients and population-based controls from the KORA, LIFE and INCIPE studies (n=4708) as well as chronic alcoholics from the GESGA consortium (n=1332) were screened with Illumina technology. For replication, three European cohorts comprising 1650 patients with non-alcoholic CP and 6695 controls originating from the same countries were used.

RESULTS

We replicated previously reported risk loci CLDN2-MORC4, CTRC, PRSS1-PRSS2 and SPINK1 in alcoholic CP patients. We identified CTRB1-CTRB2 (chymotrypsin B1 and B2) as a new risk locus with lead single-nucleotide polymorphism (SNP) rs8055167 (OR 1.35, 95% CI 1.23 to 1.6). We found that a 16.6 kb inversion in the CTRB1-CTRB2 locus was in linkage disequilibrium with the CP-associated SNPs and was best tagged by rs8048956. The association was replicated in three independent European non-alcoholic CP cohorts of 1650 patients and 6695 controls (OR 1.62, 95% CI 1.42 to 1.86). The inversion changes the expression ratio of the CTRB1 and CTRB2 isoforms and thereby affects protective trypsinogen degradation and ultimately pancreatitis risk.

CONCLUSION

An inversion in the CTRB1-CTRB2 locus modifies risk for alcoholic and non-alcoholic CP indicating that common pathomechanisms are involved in these inflammatory disorders.

Endotoxin Removal from Whole Blood by a Novel Adsorption Resin: Efficiency and Hemocompatibility

The structural component of Gram- bacteria, endotoxin (ET), induces the release of endogenous mediators of sepsis. Attempts to remove these downstream molecules in vivo, have not improved survival. However, extracorporeal strategies such as continuous renal replacement therapy or therapeutic plasmapheresis have shown benefit. We are presenting an affinity-based extracorporeal technology for the removal of ET from whole blood. The small-scale device contains an adsorbent that removed 75% of ET present in whole blood. This affinity resin displayed good hemocompatibility regarding the coagulation pathway. Minimal platelet, neutrophil and complement activation were observed. There was also no evidence of consumption of coagulation factors or cell loss. In as much as ET participates in both the inflammatory and coagulation abnormalities in sepsis, this method represents an efficient and hemocompatible way to remove ET from whole blood, which, in an extracorporeal setting, may improve the outcome of sepsis.

Detection of human elastase isoforms by the ScheBo Pancreatic Elastase 1 Test

Determination of fecal pancreatic elastase content by ELISA is a reliable, noninvasive clinical test for assessing exocrine pancreatic function. Despite the widespread use of commercial tests, their exact molecular targets remain poorly characterized. This study was undertaken to clarify which human pancreatic elastase isoforms are detected by the ScheBo Pancreatic Elastase 1 Stool Test and whether naturally occurring genetic variants influence the performance of this test. Using recombinantly expressed and purified human pancreatic proteinases, we found that the test specifically measured chymotrypsin-like elastases (CELA) 3A and 3B (CELA3A and CELA3B), while CELA2A was not detected. Inactive proelastases, active elastases, and autolyzed forms were detected with identical efficiency. CELA3B elicited approximately four times higher ELISA signal than CELA3A, and we identified Glu¹⁵⁴ in CELA3B as the critical determinant of detection. Common genetic variants of CELA3A and CELA3B had no effect on test performance, with the exception of the CELA3B variant W79R, which increased detection by 1.4-fold. Finally, none of the human trypsin and chymotrypsin isoforms were detected. We conclude that the ScheBo Pancreatic Elastase 1 Stool Test is specific for human CELA3A and CELA3B, with most of the ELISA signal attributable to CELA3B.NEW & NOTEWORTHY The ScheBo Pancreatic Elastase 1 Stool Test is widely used to assess pancreatic exocrine function, yet its molecular targets have been poorly defined. We demonstrate that, among the human pancreatic proteinases, the test measures the elastase isoform CELA3B and, to a lesser extent, CELA3A. Genetic variants of the human CELA3 isoforms have no significant effect on test performance.

Genetic Risk in Chronic Pancreatitis: The Trypsin-Dependent Pathway

Genetic investigations have provided unique insight into the mechanism of chronic pancreatitis in humans and firmly established that uncontrolled trypsin activity is a central pathogenic factor. Mutations in the PRSS1, SPINK1, and CTRC genes promote increased activation of trypsinogen to trypsin by stimulation of autoactivation or by impairing protective trypsinogen degradation and/or trypsin inhibition. Here we review key genetic and biochemical features of the trypsin-dependent pathological pathway in chronic pancreatitis.

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.

Mesotrypsin Signature Mutation in a Chymotrypsin C (CTRC) Variant Associated with Chronic Pancreatitis

Human chymotrypsin C (CTRC) protects against pancreatitis by degrading trypsinogen and thereby curtailing harmful intra-pancreatic trypsinogen activation. Loss-of-function mutations in CTRC increase the risk for chronic pancreatitis. Here we describe functional analysis of eight previously uncharacterized natural CTRC variants tested for potential defects in secretion, proteolytic stability, and catalytic activity. We found that all variants were secreted from transfected cells normally, and none suffered proteolytic degradation by trypsin. Five variants had normal enzymatic activity, whereas variant p.R29Q was catalytically inactive due to loss of activation by trypsin and variant p.S239C exhibited impaired activity possibly caused by disulfide mispairing. Surprisingly, variant p.G214R had increased activity on a small chromogenic peptide substrate but was markedly defective in cleaving bovine β-casein or the natural CTRC substrates human cationic trypsinogen and procarboxypeptidase A1. Mutation p.G214R is analogous to the evolutionary mutation in human mesotrypsin, which rendered this trypsin isoform resistant to proteinaceous inhibitors and conferred its ability to cleave these inhibitors. Similarly to the mesotrypsin phenotype, CTRC variant p.G214R was inhibited poorly by eglin C, ecotin, or a CTRC-specific variant of SGPI-2, and it readily cleaved the reactive-site peptide bonds in eglin C and ecotin. We conclude that CTRC variants p.R29Q, p.G214R, and p.S239C are risk factors for chronic pancreatitis. Furthermore, the mesotrypsin-like CTRC variant highlights how the same natural mutation in homologous pancreatic serine proteases can evolve a new physiological role or lead to pathology, determined by the biological context of protease function.

Chronic pancreatitis associated with the p.G208A variant of PRSS1 gene in a European patient

CONTEXT

The major etiologic factor of chronic pancreatitis in adults is excessive alcohol consumption, whereas among children structural anomalies, systemic and metabolic disorders, and genetic factors are prevalent. Mutations in the cationic trypsinogen gene (PRSS1) cause hereditary pancreatitis, while mutations in serine protease inhibitor Kazal type 1 (SPINK1), cystic fibrosis transmembrane conductance regulator (CFTR) and chymotrypsin C (CTRC) genes have been shown to associate with chronic pancreatitis as independent risk factors.

CASE REPORT

We present a case of 13-year-old boy with idiopathic chronic pancreatitis. Given the unexplained attacks of pancreatitis since early childhood and despite the negative family history, molecular-genetic analysis of four pancreatitis susceptibility genes (PRSS1, SPINK1, CTRC and CFTR) was performed. The boy was found to carry the c.623G>C (p.G208A) mutation of the PRSS1 gene and the c.180C>T (p.G60G) mutation of the CTRC gene, both in heterozygous state. These mutations are considered as contributing risk factors for chronic pancreatitis.

CONCLUSIONS

In children with idiopathic chronic pancreatitis genetic causes should be considered, even in absence of positive family history. To the best of our knowledge, this is the first description of a European patient with chronic pancreatitis associated with the p.G208A mutation of PRSS1 gene. This mutation was previously reported only in Asian subjects and is thought to be a unique genetic cause of pancreatitis in Asia.

HLA alleles and susceptibility to dermatological disorders associated with Helicobacter pylori infection: a significant association to HLA-Cw*06

The occurrence rate of HLA class I and class II alleles was established in 24 patients suffering from dermatological disorders associated with the Helicobacter pylori infection. The increased frequency of HLA-C*0602, 4 was found to be 0.1875 compared to 0.0733 in the control group (odds ratio: 2.913; two-sided P value: P = 0.0251). Our data suggest that the HLA-Cw6 molecule play a role in the susceptibility to the Helicobacter pylori infection.

[Trends in occupational skin diseases in the Slovak Republic]

The authors present the onsets of occupational dermatoses abroad and in the Slovak Republic, organizational measures, the so-called consulting days of commissions which co-operate with medical centres of occupational hygiene. They analyse the principles of diagnosis, relevance of epicutaneous tests, criteria of professionality, claims service, judgement and compensations of admitted claims. They analyse the developmental trends of claimed occupational skin diseases and skin infections which occurred within 1973-1998 according to their individual inducers divided into 20 classes, as well as to number of claims. They review the order of inducers according to their significance: oil products, plastic materials, rubber and rubber chemicals. The 4th class includes "other chemicals" which are to be divided according to their individual chemical composition. The proportion of occupational skin diseases in relation to all occupational diseases has gradually decreased from 51.7% in 1973 to 16.3% in 1998, in absolute figures from 382 cases in 1973 decreased to 60 cases in 1998. The authors analyse the reasons of this decrease. (Tab. 4, Ref. 39.)

Occurrence rates of HLA-DRB1, HLA-DQB1, and HLA-DPB1 alleles in patients suffering from vitiligo

By investigating a group of 39 unrelated adults suffering from vitiligo it was found that alleles HLA-DRB1*0701, -DQB1*0201, and -DPB1*1601 differed in their frequencies in comparison to those observed in the healthy population. The allele HLA-DRB1*0701 was found in 26.5% of patients compared to 14.2% in the healthy group (p < 0,01, RR = 2.17). The allele HLA-DQB1*0201 was present in 33.8% of patients compared to 21.2% (p < 0,025, RR = 1.89). The allele HLA-DPB1*1601 was found in 6.41% of patients compared to 2.05% in the healthy group (p < 0.05, RR = 3.3). No other significant deviations in the frequencies of investigated alleles were observed.

Long-term trends of the incidence of syphilis and gonorrhoea in the Slovak Republic during 1947-1994, with special regard to young age groups

During the Second World War and after the War venereal diseases (Syphilis and Gonorrhoea) were wide-spread. By a single census in October 1947 were notified 2960 syphilitic patients. In the years 1949-1951 intensive and effective preventive measures were introduced as compulsatory notification system of venereal diseases, sexual contact-tracing investigations, correct and rapid diagnosis of venereal diseases, rapid and efficient therapy of patients with syphilis, followup (post-treatment observations) for all patients, routine serological tests for syphilis, in expectant mothers at ante-natal clinics, periodical screening of high-risk groups, patients in each calendar year at their hospitalization, to taking up a post and a special drive against syphilis ("PN-action"). The results of these measures are manifested by substantial fall in the number of cases of syphilis and gonorrhoea. In the years 1948-1955 18,151 patients suffering from syphilis were notified. The changes of the incidence of syphilis and gonorrhoea are illustrated by statistical data (Tab. 1-9). Syphilis congenita occurs sporadicly, there is a substantial fall in the number of syphilitic pregnant. After 1989 there has been a greater group mobility and a substantial rise in active and passive tourisms and occupational travel activity, especially abroad. Changes of the sexual behaviour were expressed, especially a greater tolerance whether heterosexual or homosexual, sexual freedom, sexual promiscuity and especially prostitution.

[Adverse effects and side-effects of antimycotic agents]

The study lays emphasis on the significance and actuality of infections, especially in coincidence with immunodeficient states. Candidosis, mycotic diseases caused by moulds, systemic mycoses, and onychomycoses represent the major problems of modern mycology. They require usually a long-term therapy by means of highly active antimycotics. Consequently, an entire series of undesirable side-effects supervene. External applications result most frequently in contact eczemas and therefore often require preventive patch tests. Oral administration results in general hepatic, renal, hematologic and other impairments which require the monitoring of the latter parameters during therapy. Finally a considerable significance is ascribed to interaction with other simultaneously applied drugs with the antimycotics. (Tab. 1, Ref. 83.)

[Vitiligo--an enigmatic disease. II. Therapy of vitiligo]

The work gives a review of therapeutic methods of vitiligo. PUVA therapy, application of cortisonoids, khellin (including UVA), phenylalanine (including UVA), melagenina, and laser therapy represent non-surgical methods. Surgical methods include application of fluorouracil following dermabrasion, of autologous epidermal grafting transplantation of in vitro cultured epidermis, in vitro cultured melanocytes and micropigmentation by pigment. Auxiliary methods are represented by administration of carotene, using sunscreens and if necessary cosmetic treatment. Entire depigmentation is done in accordance with the extent of vitiligo, unsuccessful repigmentation and the age of the patient. The conclusion points out psychosocial aspects and the necessity of mutual cooperation of both, physician and patient. (Ref. 53.)

In vitro effects of hematopoietic growth factors on the proliferation, endoreplication, and maturation of human megakaryocytes

A liquid culture technique was used to study regulation of human megakaryocytopoiesis in vitro. Low-density cells from adult bone marrow were cultured in the presence of normal plasma, plasma from patients with aplastic marrows (AP), recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) and interleukin-3 (IL-3). Megakaryocytes (MK) were studied at day 10 of culture by a two-color staining technique using a pool of monoclonal antibodies for their identification and propidium iodide to label DNA. Their ploidy distribution was analyzed by flow cytometry. In some experiments cytoplasmic maturation was also studied by ultrastructural techniques. Normal plasma provides a low number of MK with a ploidy distribution including 8 N and 16 N MK. AP promoted in a dose-dependent manner proliferation of MK and some batches favored endoreplication. This effect was clearly demonstrated when ploidy distribution was compared between normal plasma and AP on parallel marrow cultures. However, ploidy distribution was shifted toward low values compared with uncultured MK. rhGM-CSF had no significant effect on these two parameters. In contrast, rhIL-3 from 0.1 U/mL to 100 U/mL had a proliferative effect but was unable to induce endoreplication. Furthermore, when associated with AP it totally abrogated the effect of AP on endoreplication because in most experiments more than 90% of MK were 2 N and 4 N. This effect was also observed when rhIL-3 was added after 7 days of culture (when it has little proliferative effects). Studies of the maturation of MK grown with rhIL-3 indicate that the majority were small mature cells synthesizing alpha-granules and demarcation membranes. The effect of AP on MK proliferation and endoreplication was not related to IL-6 because its IL-6 content was identical to that of normal plasma and its neutralization did not modify these parameters. In conclusion, this study indicates that liquid culture technique in association with flow cytometry could be a powerful tool in identifying the humoral regulators of human megakaryocytopoiesis.

Developmental changes in human megakaryocyte ploidy

Megakaryocytes (MK) obtained from the differentiation of MK colony-forming units (CFU-MK) were grown from fetal liver, cord blood, and adult marrow in liquid culture containing aplastic plasma. Ploidy distribution was studied by a double-staining technique and flow cytometry and MK maturation by ultrastructural techniques. Cultured MK from fetuses and neonates were small sized (about 10 microns) in comparison to adult MK. They were mature cells that contained large membrane complexes as previously found in vivo. Only 2N and 4N MK were usually present in 8- to 10-week-old fetus cultures; 8N MK were detected at 20 weeks of gestation and in neonates. Higher ploidy classes were present in culture from adults but with a much lower frequency than in marrow. Therefore, a progressive shift to higher ploidy and an increase in MK size were observed simultaneously during development. Interleukin 3 (IL-3) increased MK proliferation as in adults but abrogated MK ploidization of 20-week-old fetus culture. The present results suggest that the changes occurring during ontogenesis are related to intrinsic MK modifications because no inhibitor of MK ploidization could be detected in fetal cultures.

[Propolis allergy]

The incidence of propolis contact sensitivity was 1.2-3.3% among 7483 hospital patients during the period 1981-1987, while the prevalence among 1,558 healthy volunteers was 0.64%. A group of 26 patients with contact allergy to propolis was challenged with identified substances isolated from propolis. The mixture of 3-methyl-2-butenylester (3M2B) and 3-methyl-3-butenylester (3M3B) from caffeic acid caused a positive reaction in 7 patients, and in 5 of 9 patients there was a positive reaction to the mixture of 3M2B and 3M3B from diacetyl-caffeic acid. Among the 19 patients challenged with the flavonoid group, 3 had positive reactions, and individual derivatives of cinnamic acid caused positive reactions in 3 and 4 patients each. When five components taken from poplar buds were tested, the one that provoked the largest number of positive reactions was the methanol component (15 of 19 patients). The results show that propolis contact allergy is not caused by one main allergen, but by several allergens varying in chemical composition; the presence of these in propolis depends on the nature of the source plant and the place and time of collection by the bees.

Immunogold probing of platelet factor 4 in different ploidy classes of rat megakaryocytes sorted by flow cytometry

Different ploidy classes of rat megakaryocytes were sorted by flow cytometry from highly purified perfusion-fixed megakaryocyte cell suspensions prepared by sequential centrifugal elutriation and Percoll gradient centrifugation. Sorted cell populations were studied for the localization of platelet factor 4 (PF-4) probed with the monoclonal antibody 2E7 in order to clarify the relevance of PF-4 localization to the cytoplasmic and nuclear development of megakaryocytes. The relative numbers of labeled alpha granules and labeled alpha granule-related small vesicular structures (AGR-SVS) were quantitated using the gold-labeled antibody detection method and correlated with DNA content and cytoplasmic maturation in individual megakaryocytes. We determined that the stage of cytoplasmic maturation exerted a significant effect on the proportion of labeled alpha granules and labeled AGR-SVS. A significant interaction effect of stage and ploidy class resulted in the stage effect on proportion of labeled alpha granules being significant only in two of the three ploidy classes. The least mature cells present within each ploidy group exhibited PF-4 labeling mostly in SVS that were not related to alpha granules. During subsequent cytoplasmic maturation, more of the labeled SVS were seen related to alpha granules, with more of the mature alpha granules themselves becoming labeled. Polyploidization also affected the proportion of labeled AGR-SVS. Our data suggest that SVS play a role in the intramegakaryocytic transport of PF-4 into alpha granules. These data provide evidence of the complexity of megakaryocytic differentiation involving both cytoplasmic maturation and nuclear endoreduplication as reflected in PF-4 expression.

Regulation of human megakaryocytopoiesis: analysis of proliferation, ploidy and maturation in liquid cultures

A liquid culture technique associated with either double staining and flow cytometry or electron microscopy was used to study human megakaryocytopoiesis. During development from the embryo to the adult, a progressive increase in ploidy classes associated with an enhancement of megakaryocyte (meg) size was observed. Granulocyte-macrophage colony-stimulating factor had no effects on adult marrow cultures. In contrast, interleukin (IL) 3 induced a marked proliferation, but was unable to promote polyploidization. Furthermore, it abrogated the effects on endomitosis of aplastic plasma (AP). This negative effect on polyploidization of IL-3 could be partially dissociated from its effects on proliferation by a delayed addition in culture. AP acted on both proliferation and endoreplication, which was not due to the main hematopoietic growth factors, including IL-6. A synthesis of IL-6 was detected by in situ hybridization in cultured cells including megs which also express receptors for IL-6. These results suggest that terminal meg differentiation may be regulated by an autocrine IL-6 loop, and that megakaryocytopoiesis may be independently regulated at early and late stages of differentiation.

Ultrastructural localization of platelet factor 4 in rat megakaryocytes and platelets by gold-labeled antibody detection

The pattern of distribution of platelet factor 4 (PF-4) was studied in rat platelets and megakaryocytes following immunohistochemical labeling with a monoclonal antibody (2E7) specific for PF-4 and visualization by a protein A-gold complex. We observed a heterogeneity in PF-4 expression among alpha granules with a minority of them being unlabeled by immunoelectron microscopy, a pattern similar in both mature, circulating platelets and developing megakaryocytes. Furthermore, the majority of the labeled alpha granules in both cell types displayed a unique, eccentric localization of the PF-4 that was mainly over the nucleoid region within each granule. This localization is similar to the microtubular localization in alpha granules reported previously for von Willebrand factor and yet distinct from the reported random distribution of fibrinogen. We also observed significant labeling of small vesicular structures in developing megakaryocytes that may be involved in the transport of PF-4 and its packaging in platelet alpha granules. This new information is important in relating patterns of PF-4 biogenesis in megakaryocytes to conditions of alpha granular dysfunction in platelets.

Epidemiology of nickel allergy

In 2400 consecutive patients at 8 clinics in 5 countries, nickel hypersensitivity was found in 176 cases (7.3%), 19 male (2.1%) and 157 female (10.5%). The incidence ranged from 15 to 38 cases in 300 patients of every department (5.0% Sofia to 12.7% Erfurt). 60.6% of the nickel positives were schoolgirls or younger than 25 years. The exposure time was 3 years, in 49% 1 year or shorter. Most cases (75%) are not occupationally acquired, but due to costume jewelry (31.8%), wrist watches (23.3%), metal clothing buckles (3.4%) including jeans buttons. Job dependent nickel dermatitis is often (36/51 cases) linked with wet work. Atopic dermatitis was found in 8.3% of female nickel allergy. Nickel positivity without a dermatitis history was seen in 9/176 cases (5%). Nickel allergy will become a sex-indifferent phenomenon in Europe, because of the changing customs of adornment.