Genetische Grundlagen der chronischen Pankreatitis

Die in den letzten Jahren erhobenen genetischen Befunden untermauern das Konzept, daß ein Ungleichgewicht von Proteasen und ihren Inhibitoren wesentlich an der Pathogenese der chronischen Pankreatitis beteiligt ist. Die Identifizierung von Mutationen im kationischen Trypsinogen bei Patienten mit hereditärer Pankreatitis hat das Verständnis der Erkrankung entscheidend beeinflußt. Der Nachweis von SPINK1-, CFTR- und PRSS1-Mutationen bei Patienten ohne Familienanamnese für eine Pankreatitis deutet darauf hin, daß auch die idiopathische Pankreatitis genetisch determiniert ist. Die bisher durchgeführten Studien legen nahe, daß die erblich bedingte chronische Pankreatitis eine genetisch heterogene Erkrankung ist, die in Abhängigkeit von den defekten Genen bzw. den zugrundeliegenden Mutationen einem autosomal dominanten, einem autosomal rezessiven oder einem komplexen Erbgang folgt. Das gehäufte Auftreten von SPINK1-Mutationen bei alkoholischer chronischer Pankreatitis ist ein Hinweis darauf, daß genetische Faktoren auch zur Suszeptibilität von primär nicht erblichen Formen der chronischen Pankreatitis beitragen. Im weiteren konnte gezeigt werden, daß genetische Dispositionsfaktoren auch bei der Pathogenese der tropischen Pankreatitis einen wesentlichen Stellenwert besitzen. Diese Daten stellen das Konzept der tropischen Pankreatitis als eigene, tropenspezifische Krankheitsentität in Frage. In der vorliegenden Arbeit wurde die Bedeutung genetischer Faktoren bei der Entstehung der hereditären und idiopathischen wie der alkoholischen Pankreatitis untersucht. Die vollständige Aufklärung der genetischen Ursachen wird vermutlich die Unterscheidung zwischen hereditärer und idiopathischer bzw. tropischer chronischer Pankreatitis obsolet werden lassen. Nach Ausschluß sekundärer Ursachen sollte auch bei Patienten ohne Familienanamnese eine Genanalyse auf Mutationen in den obengenannten Genen veranlaßt werden.The recent discoveries of trypsinogen (PRSS1) and trypsin inhibitor (SPINK1) mutations in patients with hereditary and idiopathic chronic pancreatitis support the hypothesis that an inappropriate activation of pancreatic zymogens to active enzymes within the pancreatic parenchyma initiates the inflammatory process. Thus, pancreatitis may be the result of an imbalance of proteases and their inhibitors within the pancreatic parenchyma. Since the first description of inherited pancreatitis reported an autosomal dominant trait, hereditary CP was defined as an rare dominant inherited disease. Subsequently, the fact of familial clustering in one generation only, which indicates other inheritance pattern such as recessive or complex trait, was blinded out in the disease concept of hereditary CP for a long time. The Identification of PRSS1, SPINK1 and CFTR mutations in patients with so-called idiopathic chronic pancreatitis, however, shows that inherited cases of CP are much more frequent and that different mutations in different genes might lead to different inheritance pattern. Evaluation of patients with CP without an obvious predisposing factor should include genetic testing for mutations in the above mentioned genes even in the absence of a family history of pancreatitis. The finding of SPINK1 mutations in alcohol-induced pancreatitis indicates that genetic factors genetic factors may increase disease susceptibility to primary non-hereditary CP types. This work summarises the significance of genetic factors in the pathogenesis of hereditary and idiopathic as well as alcoholic chronic pancreatitis. Thus, the identification of further genes involved into the pathogenesis of inherited CP probably will also enhance our knowledge about more common types of CP such as alcoholic or tropical 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

Risk of chronic pancreatitis in carriers of loss-of-function CTRC variants: A meta-analysis

The digestive protease chymotrypsin C (CTRC) protects the pancreas against pancreatitis by degrading potentially harmful trypsinogen. Loss-of-function genetic variants in CTRC increase risk for chronic pancreatitis (CP) with variable effect size, as judged by the reported odds ratio (OR) values. Here, we performed a meta-analysis of published studies on four variants that alter the CTRC amino-acid sequence, are clinically relatively common (global carrier frequency in CP >1%), reproducibly showed association with CP and their loss of function phenotype was verified experimentally. We found strong enrichment of CTRC variants p.A73T, p.V235I, p.K247_R254del, and p.R245W in CP cases versus controls, yielding OR values of 6.5 (95% confidence interval (CI) 2.4-17.8), 4.5 (CI 2.2-9.1), 5.4 (CI 2.6-11.0), and 2.6 (CI 1.6-4.2), respectively. Subgroup analysis demonstrated disease association of variants p.K247_R254del and p.R245W in alcoholic CP with similar effect sizes as seen in the overall CP group. Homozygosity or compound heterozygosity were rare and seemed to be associated with higher risk. We also identified a so far unreported linkage disequilibrium between variant p.K247_R254del and the common c.180C>T (p.G60 =) haplotype. Taken together, the results indicate that heterozygous loss-of-function CTRC variants increase the risk for CP approximately 3-7-fold. This meta-analysis confirms the clinical significance of CTRC variants and provides further justification for the genetic screening of CP patients

A Common Variant of PNPLA3 (p.I148M) Is Not Associated with Alcoholic Chronic Pancreatitis

Contains fulltext : 110441.pdf (publisher's version ) (Open Access)BACKGROUND: Chronic pancreatitis (CP) is an inflammatory disease that in some patients leads to exocrine and endocrine dysfunction. In industrialized countries the most common aetiology is chronic alcohol abuse. Descriptions of associated genetic alterations in alcoholic CP are rare. However, a common PNPLA3 variant (p.I148M) is associated with the development of alcoholic liver cirrhosis (ALC). Since, alcoholic CP and ALC share the same aetiology PNPLA3 variant (p.I148M) possibly influences the development of alcoholic CP. METHODS: Using melting curve analysis we genotyped the variant in 1510 patients with pancreatitis or liver disease (961 German and Dutch alcoholic CP patients, 414 German patients with idiopathic or hereditary CP, and 135 patients with ALC). In addition, we included in total 2781 healthy controls in the study. RESULTS: The previously published overrepresentation of GG-genotype was replicated in our cohort of ALC (p-value <0.0001, OR 2.3, 95% CI 1.6-3.3). Distributions of genotype and allele frequencies of the p.I148M variant were comparable in patients with alcoholic CP, idiopathic and hereditary CP and in healthy controls. CONCLUSIONS: The absence of an association of PNPLA3 p.I148M with alcoholic CP seems not to point to a common pathway in the development of alcoholic CP and alcoholic liver cirrhosis

Genetic Analyses of Heme Oxygenase 1 (HMOX1) in Different Forms of Pancreatitis

Contains fulltext : 107993.pdf (publisher's version ) (Open Access)BACKGROUND: Heme oxygenase 1 (HMOX1) is the rate limiting enzyme in heme degradation and a key regulator of inflammatory processes. In animal models the course of pancreatitis was ameliorated by up-regulation of HMOX1 expression. Additionally, carbon monoxide released during heme breakdown inhibited proliferation of pancreatic stellate cells and might thereby prevent the development of chronic pancreatitis (CP). Transcription of HMOX1 in humans is influenced by a GT-repeat located in the promoter. As such, HMOX1 variants might be of importance in the pathogenesis of pancreatitis. METHODS: The GT-repeat and SNP rs2071746 were investigated with fluorescence labelled primers and by melting curve analysis in 285 patients with acute pancreatitis, 208 patients with alcoholic CP, 207 patients with idiopathic/hereditary CP, 147 patients with alcoholic liver cirrhosis, and in 289 controls, respectively. GT-repeat analysis was extended to a total of 446 alcoholic CP patients. In addition, we performed DNA sequencing in 145 patients with alcoholic CP, 138 patients with idiopathic/hereditary CP, 147 patients with alcoholic liver cirrhosis, and 151 controls. Exon 3 screening was extended to additional patients and controls. RESULTS: S- and L-alleles of the GT-repeat, genotypes and alleles of SNP rs2071746 and non-synonymous variants detected by sequencing were found with similar frequencies in all groups. CONCLUSIONS: Although functional data implicate a potential influence of HMOX1 variants on the pathogenesis of pancreatitis, we did not find any association. As rare non-synonymous HMOX1 variants were found in patients and controls, it is rather unlikely that they will have functional consequences essential for pancreatitis development

Mobile Air Quality Studies (MAQS) - an international project

Due to an increasing awareness of the potential hazardousness of air pollutants, new laws, rules and guidelines have recently been implemented globally. In this respect, numerous studies have addressed traffic-related exposure to particulate matter using stationary technology so far. By contrast, only few studies used the advanced technology of mobile exposure analysis. The Mobile Air Quality Study (MAQS) addresses the issue of air pollutant exposure by combining advanced high-granularity spatial-temporal analysis with vehicle-mounted, person-mounted and roadside sensors. The MAQS-platform will be used by international collaborators in order 1) to assess air pollutant exposure in relation to road structure, 2) to assess air pollutant exposure in relation to traffic density, 3) to assess air pollutant exposure in relation to weather conditions, 4) to compare exposure within vehicles between front and back seat (children) positions, and 5) to evaluate "traffic zone"- exposure in relation to non-"traffic zone"-exposure. Primarily, the MAQS-platform will focus on particulate matter. With the establishment of advanced mobile analysis tools, it is planed to extend the analysis to other pollutants including including NO2, SO2, nanoparticles, and ozone