OBJECTIVES: Premature activation of the digestive protease trypsin within the pancreatic parenchyma is a critical factor in the pathogenesis of pancreatitis. Alterations in genes that affect intrapancreatic trypsin activity are associated with chronic pancreatitis (CP). Recently, carboxyl ester lipase emerged as a trypsin-independent risk gene. Here, we evaluated pancreatic lipase ( PNLIP ) as a potential novel susceptibility gene for CP. METHODS: We analyzed all 13 PNLIP exons in 429 nonalcoholic patients with CP and 600 control subjects from Germany, in 632 patients and 957 controls from France, and in 223 patients and 1,070 controls from Japan by DNA sequencing. Additionally, we analyzed selected exons in further 545 patients with CP and 1,849 controls originating from Germany, United States, and India. We assessed the cellular secretion, lipase activity, and proteolytic stability of recombinant PNLIP variants. RESULTS: In the German discovery cohort, 8/429 (1.9%) patients and 2/600 (0.3%) controls carried a PNLIP missense variant ( P = 0.02, odds ratio [OR] = 5.7, 95% confidence interval [CI] = 1.1–38.9). Variants detected in patients were prone to proteolytic degradation by trypsin and chymotrypsin. In the French replication cohort, protease-sensitive variants were also enriched in patients with early-onset CP (5/632 [0.8%]) vs controls (1/957 [0.1%]) ( P = 0.04, OR = 7.6, 95% CI = 0.9–172.9). In contrast, we detected no protease-sensitive variants in the non-European populations. In the combined European data, protease-sensitive variants were found in 13/1,163 cases (1.1%) and in 3/3,000 controls (0.1%) (OR = 11.3, 95% CI = 3.0–49.9, P < 0.0001). CONCLUSIONS: Our data indicate that protease-sensitive PNLIP variants are novel genetic risk factors for the development of CP.
Einleitung: Eine relevante Nebenwirkung der Therapie einer PAH mit Bosentan ist die Erhöhung der Transaminasen. Bosentan wird über das Cytochrom CYP2C9 metabolisiert. Die Stoffwechselprodukte werden über die Gallensalzexportpumpe („bile salt export pump„, BSEP, kodiert durch das ABCB11 Gen) aus der Leberzelle transportiert. Genetische Varianten von CYP2C9 (Allele CYP2C9*2 und CYP2C9*3) treten bei Kaukasiern mit hoher Frequenz auf und sind mit einer verminderten Enzymaktivität assoziiert. Eine häufige Variante des ABCB11 Gens, rs2287622, führt zu einem Aminosäureaustausch p.V444A und ist mit einer verminderten BSEP Expression und dem Risiko eines medikamentös-induzierten Leberschadens assoziiert.
In chronic pancreatitis (CP), alterations in several genes have so far been described, but only small cohorts have been extensively investigated for all predisposing genes.
Design
660 patients with idiopathic or hereditary CP and up to 1758 controls were enrolled. PRSS1, SPINK1 and CTRC were analysed by DNA sequencing, and cystic fibrosis transmembrane conductance regulator (CFTR) by melting curve analysis.
Results
Frequencies of CFTR variants p.R75Q, p.I148T, 5T-allele and p.E528E were comparable in patients and controls. We identified 103 CFTR variants, which represents a 2.7-fold risk increase (p<0.0001). Severe cystic fibrosis (CF)-causing variants increased the risk of developing CP 2.9-fold, and mild CF-causing variants 4.5-fold (p<0.0001 for both). Combined CF-causing variants increased CP risk 3.4-fold (p<0.0001), while non-CF-causing variants displayed a 1.5-fold over-representation in patients (p=0.14). CFTR compound heterozygous status with variant classes CF-causing severe and mild represented an OR of 16.1 (p<0.0001). Notably, only 9/660 (1.4%) patients were compound heterozygotes in this category. Trans-heterozygosity increased CP risk, with an OR of 38.7, with 43/660 (6.5%) patients and 3/1667 (0.2%) controls being trans-heterozygous (p<0.0001).
Conclusions
Accumulation of CFTR variants in CP is less pronounced than reported previously, with ORs between 2.7 and 4.5. Only CF-causing variants reached statistical significance. Compound and trans-heterozygosity is an overt risk factor for the development of CP, but the number of CFTR compound heterozygotes in particular is rather low. In summary, the study demonstrates the complexity of genetic interactions in CP and a minor influence of CFTR alterations in CP development.
Introduction: Quantitative trait locus mapping in the inbred mouse model of cholesterol cholelithiasis identified a gallstone-susceptibility (Lith) locus on mouse chromosome 11, which co-localizes with the Il4 gene. In addition, ablation of Il4 promoted cholesterol gallstone formation in the mouse model of cholelithiasis rendering IL4 an interesting LITH-candidate gene. Methods: To systematically explore the IL4 gene as a LITH gene in humans, we performed a genetic association study in gallstone carriers (N=184) and control subjects without evidence for gallstones (N=833) from a self-contained population of Sorbs from Saxony. Based on the HapMap database, three haplotype-tagging single nucleotide polymorphisms (SNPs) (rs2243290, rs2227284 and rs2243263) capturing the genetic variation of IL4 (r2 cut-off 0.8; minor allele frequency >0.05) were genotyped in cases and controls employing the TaqMan method. Data were analyzed in the additive model using logistic regression including age, sex and body mass index as covariates. Results: Two of the three SNPs were associated with cholelithiasis, rs2243290 (P=0.06) and rs2227284 (P=0.02). In addition, when only cases with a previous history of a cholecystectomy were considered, both SNPs were significantly associated with symptomatic gallstone disease (rs2243290 (P=0.009); rs2227284 (P=0.002)). For both SNPs, an increase in gallstone susceptibility was associated with the variant minor allele. Conclusion: Our results indicate an increased gallstone risk from frequent variants of IL4. Anti-inflammatory effects might explain a protective effect of IL4 on cholelithiasis by up-regulation of PPARgamma and a reduction of leukotriene production by inhibition of the arachodinate-5-lipoxygenase leading to a diminished production of mucin glycoproteins. Accordingly, our findings suggest that IL4 could be a target for prevention and non-surgical management of cholelithiasis in genetically predisposed patients.
Einleitung: Voraussetzungen für die Bildung von Cholesteringallensteinen sind die Übersättigung der Galle mit Cholesterol, ein Muzingel in der Gallenblase sowie eine gestörte Gallenblasenmotilität. GPBAR1 (auch als TGR5 bezeichnet) kodiert für einen G-Protein gekoppelten Rezeptor, der u.a. auf den Gallenblasenepithelzellen exprimiert wird. GPBAR1 defiziente Mäuse sind als gallensteinresistent beschrieben. Weiterhin ist GPBAR1 auf enteroendokrinen Zellen exprimiert und reguliert die Expression von GLP-1, das als Sättigungshormon wirkt und die Insulinsekretion stimuliert.
