A recombined allele of the lipase gene CEL and its pseudogene CELP confers susceptibility to chronic pancreatitis

Carboxyl-ester lipase is a digestive pancreatic enzyme encoded by the highly polymorphic CEL gene¹. Mutations in CEL cause maturity-onset diabetes of the young (MODY) with pancreatic exocrine dysfunction². Here we identified a hybrid allele (CEL-HYB), originating from a crossover between CEL and its neighboring pseudogene CELP. In a discovery cohort of familial chronic pancreatitis cases, the carrier frequency of CEL-HYB was 14.1% (10/71) compared with 1.0% (5/478) in controls (odds ratio [OR] = 15.5, 95% confidence interval [CI] = 5.1-46.9, P = 1.3 × 10⁻⁶). Three replication studies in non-alcoholic chronic pancreatitis cohorts identified CEL-HYB in a total of 3.7% (42/1,122) cases and 0.7% (30/4,152) controls (OR = 5.2, 95% CI = 3.2-8.5, P = 1.2 × 10⁻¹¹; formal meta-analysis). The allele was also enriched in alcoholic chronic pancreatitis. Expression of CEL-HYB in cellular models revealed reduced lipolytic activity, impaired secretion, prominent intracellular accumulation and induced autophagy. The hybrid variant of CEL is the first chronic pancreatitis gene identified outside the protease/antiprotease system of pancreatic acinar cells.

Noninvasive characterization of graft steatosis after liver transplantation

OBJECTIVE

Liver graft steatosis has not been noninvasively evaluated yet. We therefore characterized liver transplant recipients by transient elastography (TE) and controlled attenuation parameter (CAP) and correlated the results with clinical and genetic risk factors.

METHODS

A total of 204 patients (pretransplant disease: n = 102 nonalcoholic etiology, nonalcoholic liver cirrhosis (non-ALC); n = 102 alcoholic liver disease, ALC; 42% female; median age 57.8 years; median time since transplantation 66 months) underwent ultrasound, TE, CAP, and nonalcoholic fatty liver disease (NAFLD) fibrosis score. Recipient DNA samples were genotyped for patatin-like phospholipase domain-containing protein 3 (PNPLA3) (rs738409) and IL28B (rs8099917, rs12979860) polymorphisms.

RESULTS

Increased hepatic echogenicity at ultrasound was observed in 36% of patients, CAP values >252 and >300 dB/m indicated steatosis and advanced steatosis in 44% and 24% of individuals. Advanced fibrosis (TE >7.9 kPa) was associated with increased CAP results (266 vs. 229 dB/m, p = 0.012). PNPLA3 G-allele carriers had increased CAP values (257 vs. 222 dB/m, p = 0.032), higher liver stiffness (TE 6.4 vs. 5.5 kPa, p = 0.005), and prevalence of diabetes mellitus (40% vs. 22%, p = 0.016). No such association was observed for IL28B polymorphisms. ALC compared to non-ALC patients had higher body mass index (28.1 vs. 25.5 kg/m², p < 0.001), higher prevalence of diabetes mellitus (41% vs. 25%, p = 0.017), and PNPLA3 CG + GG genotype (73% vs. 47%, p = 0.006), and had elevated TE (6.3 vs. 5.4 kPa, p = 0.022), CAP (266 vs. 221 dB/m, p = 0.001), and NAFLD fibrosis score (score -0.5 vs. -1.3, p < 0.001).

CONCLUSION

Modern noninvasive liver graft assessment frequently detects hepatic steatosis, which is associated with graft fibrosis, components of the metabolic syndrome and recipient PNPLA3 rs738409 genotype, especially in ALC patients.

A common polymorphism in the NCAN gene is associated with hepatocellular carcinoma in alcoholic liver disease

BACKGROUND & AIMS

The genetic background of alcoholic liver diseases and their complications are increasingly recognized. A common polymorphism in the neurocan (NCAN) gene, which is known to be expressed in neuronal tissue, has been identified as a risk factor for non-alcoholic fatty liver disease (NAFLD). We investigated if this polymorphism may also be related to alcoholic liver disease (ALD) and hepatocellular carcinoma (HCC).

METHODS

We analysed the distribution of the NCAN rs2228603 genotypes in 356 patients with alcoholic liver cirrhosis, 126 patients with alcoholic HCC, 382 persons with alcohol abuse without liver damage, 362 healthy controls and in 171 patients with hepatitis C virus (HCV) associated HCC. Furthermore, a validation cohort of 229 patients with alcoholic cirrhosis (83 with HCC) was analysed. The genotypes were determined by LightSNiP assays. The expression of NCAN was studied by RT-PCR and immunofluorescence microscopy.

RESULTS

The frequency of the NCAN rs2228603 T allele was significantly increased in patients with HCC due to ALD (15.1%) compared to alcoholic cirrhosis without HCC (9.3%), alcoholic controls (7.2%), healthy controls (7.9%), and HCV associated HCC (9.1%). This finding was confirmed in the validation cohort (15.7% vs. 6.8%, OR=2.53; 95%CI: 1.36-4.68; p=0.0025) and by multivariate analysis (OR=1.840; 95%CI: 1.22-2.78; p=0.004 for carriage of the rs2228603 T allele). In addition, we identified and localised NCAN expression in human liver.

CONCLUSIONS

NCAN is not only expressed in neuronal tissue, but also in the liver. Its rs2228603 polymorphism is a risk factor for HCC in ALD, but not in HCV infection.

[Intraductal papillary mucinous neoplasm of the pancreas]

The diagnosis of cystic pancreatic lesions is raised more often within the last years. This is due to the fact that diagnostic opportunities and modalities such as endosonography (EUS), magnetic resonance imaging (MRI), magnetic resonance cholangio-pancreatography (MRCP), and computertomography (CT) have both improved and are more widely used. As such new recommendations were needed, since the knowledge on cystic pancreatic lesions has increased after the last consensus statement published in 2006.  In this review the main aspects of the recent consensus statements for diagnosis and therapy or in some cases the surveillance strategy of intraductal papillary mucinous neoplasm will be summarized. Main duct IPMN will in most cases in surgically "fit" patients be resected, since the risk of malignancy is high in this entity. In patients with branch duct IPMN a careful "watch and wait" strategy can be applied if no "worrisome features" or "high-risk stigmata" can be detected. MRI is the imaging modality of choice, while EUS should be applied in centers with expertise.

Genetic and biochemical evidence for a functional role of BACE1 in the regulation of insulin mRNA expression

OBJECTIVE

Beta-site amyloid precursor protein cleaving enzyme (BACE1) is highly expressed in pancreatic β-cells. The BACE1 gene is located in a region associated with a high diabetes risk in PIMA Indians.

DESIGN AND METHODS

INS-1E cells were used to study the impact of siRNA-mediated BACE1 knockdown and glucose metabolism was characterized in Bace1(-/-) mice. BACE1 gene was sequenced in DNA samples from 48 subjects and 13 representative single nucleotide polymorphisms (SNPs) were then genotyped for association studies in 1,527 Caucasians.

RESULTS

Reduction of Bace1 expression results in a significant decrease in insulin mRNA expression in INS-1E cells. Bace1(-/-) mice display significantly lower body weight, lower plasma insulin concentrations, but normal glucose tolerance and insulin sensitivity. In a case-control study including 538 healthy controls and 989 patients with type 2 diabetes (T2D), one SNP (rs535860) was significantly associated with T2D (P < 3.5 × 10(-5) , adjusted for age, sex, and BMI).

CONCLUSIONS

Reduced Bace1 expression causes impaired insulin expression in pancreatic β-cells of Bace1(-/-) mice, suggesting that BACE1 plays a role in the regulation of insulin biogenesis. The functionally relevant rs535860 SNP may decrease BACE1 expression by creating a new miR-661 binding site and could therefore contribute to T2D development.

Influence of the CXCL1 rs4074 A allele on alcohol induced cirrhosis and HCC in patients of European descent

BACKGROUND AND AIMS

CXCL1 (CXC chemokine-ligand-1) is a ligand for CXC chemokine receptor 2 expressed on hepatic stellate cells (HSC). Thus, CXCL1 might contribute to HSC activation and fibrogenesis. In the present study, we investigated the influence of the CXCL1 rs4074 polymorphism on the occurrence of alcohol induced liver cirrhosis and hepatocellular carcinoma (HCC).

METHODS

The study involved 458 patients with alcoholic cirrhosis (170 with HCC), 115 alcoholics without liver disease and 342 healthy controls. All subjects were genotyped for the CXCL1 rs4074 polymorphism and CXCL1 serum levels of 132 patients were measured. In vitro CXCL1 secretion in TLR-transfected cell lines were studied by ELISA.

RESULTS

Distribution of the CXCL1 genotypes (GG/GA/AA) was 159/219/80 in patients with alcoholic cirrhosis, 52/44/19 in alcoholic controls and 158/140/44 in healthy controls. Patients with alcohol-induced cirrhosis were significantly more often carriers of the CXCL1 rs4074 A allele (65.3%) than alcoholics without liver disease (54.8%, OR=1.55; 95%CI=1.025-2.350; p=0.04) and healthy controls (53.8%, OR=1.62; 95%CI=1.212-2.151; p=0.001). Accordingly, the frequency of the CXCL1 rs4074 A allele was significantly higher in the cirrhotic patients than in the subjects without cirrhosis (41.4% vs. 33.9%, OR=1.38, 95% CI:1.14-1.66, p=0.001). Furthermore cirrhotic carriers of the CXCL1 rs4074 A allele had significantly higher CXCL1 serum levels than carriers of the GG genotype. In contrast to sera from healthy controls, sera from patients with alcoholic cirrhosis induced CXCL1 secretion in TLR2- (p=0.016) and TLR4- (p=0.008) transfected HEK293 cells. This finding indicates that sera from patients with alcoholic cirrhosis contain soluble ligands that can induce CXCL1 production via stimulation of TLRs.

CONCLUSION

The enhanced CXCL1 serum levels in carriers of the rs4074 A allele together with their increased frequency in patients with alcohol induced cirrhosis suggest the CXCL1 rs4074 A allele as a genetic risk factor for alcoholic cirrhosis.

When in doubt, take it out? Cholestasis and obstructive gastric outlet syndrome in a patient with suspected chronic pancreatitis

In some patients with tumors located in the pancreas or in the periampullary region, the decision to perform a surgical resection can be difficult. In patients with concomitant chronic pancreatitis this decision can be even more challenging, since a definitive preoperative differentiation between non-malignant and malignant tumors in many cases is not possible. Clinical symptoms or complications from the tumor often direct a rational treatment strategy. For therapeutic decisions, an interdisciplinary discussion of all diagnostic findings by experienced clinicians is needed. However, in rare cases, like the one presented here, an uncommon non-malignant entity like a periampullary hamartoma may be only diagnosed after surgical resection.

CFTR, SPINK1, CTRC and PRSS1 variants in chronic pancreatitis: is the role of mutated CFTR overestimated?

OBJECTIVE

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.

Pre-study protocol MagPEP: a multicentre randomized controlled trial of magnesium sulphate in the prevention of post-ERCP pancreatitis

Background

Acute pancreatitis is the most common complication of diagnostic and therapeutic endoscopic retrograde cholangiopancreatography (ERCP). In spite of continuing research, no pharmacologic agent capable of effectively reducing the incidence of ERCP-induced pancreatitis has found its way into clinical practise. A number of experimental studies suggest that intrapancreatic calcium concentrations play an important role in the initiation of intracellular protease activation, an initiating step in the course of acute pancreatitis. Magnesium can act as a calcium-antagonist and counteracts effects in calcium signalling. It can thereby attenuate the intracellular activation of proteolytic digestive enzymes in the pancreas and reduces the severity of experimental pancreatitis when administered either intravenously or as a food supplement.

Methods

We designed a randomized, double-blind, placebo-controlled phase III study to test whether the administration of intravenous magnesium sulphate before and after ERCP reduces the incidence and the severity of post-ERCP pancreatitis. A total of 502 adult patients with a medical indication for ERCP are to be randomized to receive either 4930 mg magnesium sulphate (= 20 mmol magnesium) or placebo 60 min before and 6 hours after ERCP. The incidence of clinical post-ERCP pancreatitis, hyperlipasemia, pain levels, use of analgetics and length of hospital stay will be evaluated.

Conclusions

If magnesium sulphate is found to be effective in preventing post-ERCP pancreatitis, this inexpensive agent with limited adverse effects could be used as a routine pharmacological prophylaxis.

Trial registration

Current Controlled Trials ISRCTN46556454

Genetic analyses of heme oxygenase 1 (HMOX1) in different forms of pancreatitis

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.

A common variant of PNPLA3 (p.I148M) is not associated with alcoholic chronic pancreatitis

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.

Common CFTR haplotypes and susceptibility to chronic pancreatitis and congenital bilateral absence of the vas deferens

CFTR mutations enhance susceptibility for idiopathic chronic pancreatitis (ICP) and congenital bilateral absence of the vas deferens (CBAVD); however, it is unknown why CFTR heterozygotes are at increased disease risk. We recently showed that common CFTR variants are associated with aberrantly spliced transcripts. Here, we genotyped for common CFTR variants and tested for associations in two ICP (ICP-A: 126 patients, 319 controls; ICP-B: 666 patients, 1,181 controls) and a CBAVD population (305 patients, 319 controls). Haplotype H10 (TG11-T7-470V) conferred protection (ICP-A: OR 0.19, P<0.0001; ICP-B: OR 0.78, P = 0.06; CBAVD OR 0.08, P<0.001), whereas haplotype H3 (TG10-T7-470M) increased disease risk (ICP-A: OR 8.34, P = 0.003; ICP-B: OR 1.88, P = 0.007; CBAVD: OR 5.67, P = 0.01). The risk of heterozygous CFTR mutations carriers for ICP (OR 2.44, P<0.001) and CBAVD (OR 14.73, P<0.001) was fully abrogated by the H10/H10 genotype. Similarly, ICP risk of heterozygous p.Asn34Ser SPINK1 mutation carriers (OR 10.34, P<0.001) was compensated by H10/H10. Thus, common CFTR haplotypes modulate ICP and CBAVD susceptibility alone and in heterozygous CFTR and p.Asn34Ser mutation carriers. Determination of these haplotypes helps to stratify carriers into high- and low-risk subjects, providing helpful information for genetic counseling.

Acoustic radiation force impulse (ARFI) elastography in acute liver failure: necrosis mimics cirrhosis

Acoustic radiation force Impulse (ARFI) technology correlates shear-wave velocity with fibrosis. It can differentiate between advanced fibrosis and normal tissue in chronic liver disease. However, specificity is impaired by cholestasis, inflammation or oedema in acute hepatitis. In patients with acute liver failure (ALF) necessitating liver transplantation ARFI has not been evaluated yet. We investigated 3 patients with ALF and compared their ARFI results to those of healthy controls (n = 33) and cases with liver cirrhosis (n = 21). In the 3 ALF patients shear-wave velocities were 3.0, 2.5, and 2.7 m/s, respectively. These results were significantly increased compared to those of healthy controls (median: 1.13 m/s; p < 0.001) and similar to those of cirrhotic individuals (median: 2.93 m/s). Two individuals underwent liver transplantation. Explants showed massive necrosis, but no signs of chronic liver disease. Patient 3 recovered spontaneously and showed decreasing ARFI results during follow-up. In conclusion, hepatic necrosis can mimic liver cirrhosis at ARFI evaluation in ALF patients and this impairs the specificity of ARFI.

Sequence analysis of the human tyrosylprotein sulfotransferase-2 gene in subjects with chronic pancreatitis

BACKGROUND/AIMS

Human trypsinogens are post-translationally sulfated on Tyr154 by the Golgi resident enzyme tyrosylprotein sulfotransferase-2 (TPST2). Tyrosine sulfation stimulates the autoactivation of human cationic trypsinogen. Because increased trypsinogen autoactivation has been implicated as a pathogenic mechanism in chronic pancreatitis, we hypothesized that genetic variants of TPST2 might alter the risk for the disease.

METHODS

We sequenced the 4 protein-coding exons and the adjacent intronic sequences of TPST2 in 151 subjects with chronic pancreatitis and in 169 healthy controls. The functional effect of TPST2 variants on trypsinogen sulfation was analyzed in transfected HEK 293T cells.

RESULTS

We detected 10 common polymorphic variants, including 6 synonymous variants and 4 intronic variants, with similar frequencies in patients and controls. None of the 8 common haplotypes reconstructed from the frequent variants showed an association with chronic pancreatitis. In addition, we identified 5 rare TPST2 variants, which included 3 synonymous alterations, the c.458G>A (p.R153H) nonsynonymous variant and the c.-9C>T variant in the 5' untranslated region. The p.R153H variant was found in a family with hereditary pancreatitis; however, it did not segregate with the disease. In functional assays, both the p.R153H and c.-9C>T TPST2 variants catalyzed trypsinogen sulfation as well as wild-type TPST2.

CONCLUSION

Genetic variants of human TPST2 exert no influence on the risk of chronic pancreatitis.