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.

Rapid progression of a splenic aneurysm due to segmental arterial mediolysis: a rare cause of acute pancreatitis

BACKGROUND

The etiology of acute pancreatitis can be manifold, beside the usual causes. We are reporting an unusual cause that triggered acute pancreatitis.

PATIENT & RESULTS

A 50 year-old male experienced attacks of acute pancreatitis (abdominal pain and elevated amylase and lipase) during sexual arousal. Serial imaging showed a rapidly-progressing, partly-thrombosed splenic artery aneurysm, with local compression of the pancreas. After angiographic coiling, the attacks subsided. Further angiography revealed additional aneurysms consistent with segmental arterial mediolysis at other sites of the body. Molecular analysis regarding Ehlers-Danlos-syndrome and genetic factors for pancreatitis, autoantibodies and Syphilis serology was negative.

CONCLUSIONS

Acute pancreatitis was triggered by a transient rise in blood pressure during sexual stimulation, which caused rapid progression of a splenic artery aneurysm as part of systemic segmental arterial mediolysis.

The effect of third-party reporting on adoption of evidence-based mesalazine regimens in ulcerative colitis: an observational study

BACKGROUND AND AIMS

The optimal mesalazine dosing strategy for ulcerative colitis (UC) continues to evolve. The current study aimed to explore whether documenting drug use could prompt changes in prescribing habits.

METHODS

In a multicenter, prospective, observational study, outpatients with active or quiescent UC were enrolled if they were receiving, or were planned to receive, sustained release mesalazine microgranules (Pentasa). Clinical and prescribing data were collected at study entry, after 2 and 8 weeks. Physician-reported influences on prescribing decisions were recorded at study entry.

RESULTS

360 patients were analyzed (203 active UC, 157 remission). Prior to study entry, the range of oral mesalazine doses was 0.50-6.00 g/day in active UC patients, and 0.50-4.00 g/day for patients in remission. These changed to 1.50-5.00 g/day and 1.00-4.00 g/day, respectively, at study entry with little change thereafter. Use of a single daily mesalazine dose increased from 16.7% to 58.0% of active cases during the study, and from 5.9% to 46.8% in remission cases. Gastroenterologists reported that their basis for prescription decision-making was most frequently medical experience (80.8%), followed by guidelines (67.2%), further education or colleagues' recommendations (50.0%) and current study results (20.0%).

CONCLUSION

In this analysis of mesalazine dosing in routine clinical practice, there was an improvement in adherence to European Crohn's and Colitis Organisation (ECCO) guidelines and in use of once-daily dosing, consistent with recent trial results, following documentation of dosing regimens. Written reporting of drug dosing schedules should be considered fundamental for chronic, complex diseases such as UC.

Conservative management

Treatment of diverticulitis comprises at least two options: conservative or surgical management. There is a recent trend to limit surgical treatment of acute diverticulitis and to favor conservative management. This review addresses general aspects of conservative patient care with special focus on the treatment of patients with a first attack of diverticulitis. The presentation does not include a discussion of specific drugs which is given in other sections of this issue.

Mesalazine granules are superior to Eudragit-L-coated mesalazine tablets for induction of remission in distal ulcerative colitis - a pooled analysis

BACKGROUND

Different oral formulations of 'mesalazine (mesalamine)' may have different efficacy in distal ulcerative colitis.

AIM

To evaluate the efficacy of mesalazine granules (Salofalk granules) vs. mesalazine tablets (Salofalk tablets) as induction therapy in patients with distinct extensions of ulcerative colitis.

METHODS

A pooled analysis of 705 patients from four prospective, randomised, double-blind phase III trials was performed. The efficacy of 8 weeks' induction with 3 g/day mesalazine granules [3 g once daily (o.d.) or 1 g three times daily (t.d.s)] vs. 3 g/day mesalazine tablets (1 g t.d.s.) was compared in terms of clinical remission (CR: CAI ≤ 4) and endoscopic remission (ER: EI ≤ 3) (both according to Rachmilewitz) in subgroups with pancolitis, left-sided colitis, or proctosigmoiditis.

RESULTS

Mesalazine granules were equipotent to mesalazine tablets in pancolitis regarding CR (72% vs. 71%, P = 0.909) and ER (58% vs. 49%, P = 0.338). In left-sided colitis, both mesalazine formulations were equipotent regarding CR (66% vs. 67%; P = 0.843) but mesalazine granules were superior regarding ER (56% vs. 37%; P = 0.025). In proctosigmoiditis, mesalazine granules were significantly more effective than mesalazine tablets regarding CR (78% vs. 55% P < 0.001) and ER (67% vs. 43% P < 0.001). Furthermore, o.d. application of mesalazine granules was more effective than t.d.s. dosing in left-sided colitis (CR 73% vs. 62%, P = 0.181; ER 71% vs. 48% P = 0.005) and proctosigmoiditis (CR 86% vs. 73%, P = 0.020; ER 75% vs. 61%, P = 0.021), but not in pancolitis.

CONCLUSION

This pooled analysis supports the hypothesis that mesalazine granules are superior to mesalazine tablets in induction of remission in distal colitis and should be taken once daily.

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.

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.

A degradation-sensitive anionic trypsinogen (PRSS2) variant protects against chronic pancreatitis

Chronic pancreatitis is a common inflammatory disease of the pancreas. Mutations in the genes encoding cationic trypsinogen (PRSS1) and the pancreatic secretory trypsin inhibitor (SPINK1) are associated with chronic pancreatitis. Because increased proteolytic activity owing to mutated PRSS1 enhances the risk for chronic pancreatitis, mutations in the gene encoding anionic trypsinogen (PRSS2) may also predispose to disease. Here we analyzed PRSS2 in individuals with chronic pancreatitis and controls and found, to our surprise, that a variant of codon 191 (G191R) is overrepresented in control subjects: G191R was present in 220/6,459 (3.4%) controls but in only 32/2,466 (1.3%) affected individuals (odds ratio 0.37; P = 1.1 x 10(-8)). Upon activation by enterokinase or trypsin, purified recombinant G191R protein showed a complete loss of trypsin activity owing to the introduction of a new tryptic cleavage site that renders the enzyme hypersensitive to autocatalytic proteolysis. In conclusion, the G191R variant of PRSS2 mitigates intrapancreatic trypsin activity and thereby protects against chronic pancreatitis.

Genetics and pancreatic disease

The recognition that variations in the DNA sequence of key genes predispose individuals to acute pancreatitis, chronic pancreatitis, and pancreatic cancer represents one of the greatest breakthroughs in pancreas research. This review highlights recent progress in understanding mutations in the cationic trypsinogen gene, the pancreatic secretory trypsin inhibitor gene, and the cystic fibrosis transmembrane conductance regulator gene with respect to pancreatitis. It also notes progress in the use of microarray technology, classification of chronic pancreatitis, and predisposition to pancreatic cancer.

A new susceptibility locus for autosomal dominant pancreatic cancer maps to chromosome 4q32-34

Pancreatic cancer is the fifth leading cause of cancer death in the United States. Nearly every person diagnosed with pancreatic cancer will die from it, usually in <6 mo. Familial clustering of pancreatic cancers is commonly recognized, with an autosomal dominant inheritance pattern in approximately 10% of all cases. However, the late age at disease onset and rapid demise of affected individuals markedly hamper collection of biological samples. We report a genetic linkage scan of family X with an autosomal dominant pancreatic cancer with early onset and high penetrance. For the study of this family, we have developed an endoscopic surveillance program that allows the early detection of cancer and its precursor, before family members have died of the disease. In a genomewide screening of 373 microsatellite markers, we found significant linkage (maximum LOD score 4.56 in two-point analysis and 5.36 in three-point analysis) on chromosome 4q32-34, providing evidence for a major locus for pancreatic cancer.

Novel cationic trypsinogen (PRSS1) N29T and R122C mutations cause autosomal dominant hereditary pancreatitis

Hereditary pancreatitis (HP) is usually caused by mutations in the cationic trypsinogen (PRSS1) gene, especially R122H or N29I. We sequenced the PRSS1 gene in the proband of families without these common mutations. Novel R122C and N29T mutations were detected in independent families that segregated with the disease in an autosomal dominant fashion. The R122C mutation eliminates the arginine autolysis site as with R122H mutations. The N29T mutation may also enhance intrapancreatic trypsin activity as has been demonstrated in vitro. Identification of these new mutations requires special attention as commonly used detection methods may fail.

High-density genome scan in Crohn disease shows confirmed linkage to chromosome 14q11-12

Epidemiological studies have shown that genetic factors contribute to the pathogenesis of the idiopathic inflammatory bowel diseases (IBD), Crohn disease (CD) and ulcerative colitis (UC). Recent genome scans and replication studies have identified replicated linkage between CD and a locus on chromosome 16 (the IBD1 locus), replicated linkage between IBD (especially UC) and a locus on chromosome 12q (the IBD2 locus), and replicated linkage between IBD (especially CD) and a locus on chromosome 6p (the IBD3 locus). Since the estimated locus-specific lambdas values for the regions of replicated linkage do not account for the overall lambdas in CD, and since the published genome scans in IBD show at least nominal evidence for linkage to regions on all but two chromosomes, we performed an independent genome scan using 751 microsatellite loci in 127 CD-affected relative pairs from 62 families. Single-point nonparametric linkage analysis using the GENEHUNTER-PLUS program shows evidence for linkage to the adjacent D14S261 and D14S283 loci on chromosome 14q11-12 (LOD = 3.00 and 1.70, respectively), and the maximal multipoint LOD score is observed at D14S261 (LOD = 3.60). In the multipoint analysis, nominal evidence for linkage (P<.05) is observed near D2S117 (LOD = 1.25), near D3S3045 (LOD = 1.31), between D7S40 and D7S648 (LOD = 0.91), and near D18S61 (LOD = 1.15). Our finding of significant linkage to D14S261 and the finding of suggestive linkage to the same locus in an independent study (multipoint LOD = 2.8) satisfies criteria for confirmed linkage, so we propose that the region of interest on chromosome 14q11-12 should be designated the IBD4 locus.

Effect of 7-day therapy with different doses of the proton pump inhibitor lansoprazole on the intragastric pH in healthy human subjects

BACKGROUND

Systematic, randomized, and controlled studies on the effect of low to high doses of the proton pump inhibitor lansoprazole on intragastric acidity and plasma gastrin levels have not previously been performed.

METHODS

We investigated the effect of 7-day therapy with different doses of lansoprazole (15 mg once or twice daily, 30 mg once or twice daily, and 15 mg three times daily) on intragastric acidity and meal-stimulated daytime plasma gastrin levels in 12 healthy Helicobacter pylori-negative human subjects in a randomized, double-blind, placebo-controlled, 6-way crossover study. On days 1, 2, and 7 of the study 24-h intragastric pH-metry and 12-h integrated daytime plasma gastrin determinations were done.

RESULTS

Lansoprazole in a dose regimen of 1 x 30 mg/day, 3 x 15 mg/daily, and 2 x 30 mg/day significantly (P < 0.05) increased the intragastric 24-h median pH on days 1, 2, and 7 of therapy as compared with placebo. Lansoprazole in doses of 1 x 15 mg/day and 2 x 15 mg/day significantly increased the intragastric 24-h median pH on days 2 and 7 but not on day 1 of therapy. Doses of 3 x 15 mg and 2 x 30 mg lansoprazole daily significantly increased the intragastric 24-h median pH on days 2 and 7 of treatment as compared with 1 x 30 mg lansoprazole daily. Except for 1 x 15 mg lansoprazole on day 1 of therapy, all given dose regimens of lansoprazole (15-60 mg/day) significantly (P < 0.05) stimulated the 12-h integrated meal-stimulated daytime plasma gastrin response (pM x min) on days 1, 2, and 7 of therapy as compared with placebo.

CONCLUSION

A dose of 1 x 30 mg/day is nearly as potent as higher dose regimens of lansoprazole. Thus it most likely is the optimum dose for therapy of gastric and duodenal peptic lesions. A dose of 1 x 15 mg lansoprazole daily is a potent inhibitor of gastric acid output and could be a therapeutic dose for prevention of peptic lesions (that is, reflux oesophagitis or ulcers).