Marcel Janse

Extended analysis of a genome-wide association study in primary sclerosing cholangitis detects multiple novel risk loci

BACKGROUND & AIMS A limited number of genetic risk factors have been reported in primary sclerosing cholangitis (PSC). To discover further genetic susceptibility factors for PSC, we followed up on a second tier of single nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS). METHODS We analyzed 45 SNPs in 1221 PSC cases and 3508 controls. The association results from the replication analysis and the original GWAS (715 PSC cases and 2962 controls) were combined in a meta-analysis comprising 1936 PSC cases and 6470 controls. We performed an analysis of bile microbial community composition in 39 PSC patients by 16S rRNA sequencing. RESULTS Seventeen SNPs representing 12 distinct genetic loci achieved nominal significance (p(replication) <0.05) in the replication. The most robust novel association was detected at chromosome 1p36 (rs3748816; p(combined)=2.1 × 10(-8)) where the MMEL1 and TNFRSF14 genes represent potential disease genes. Eight additional novel loci showed suggestive evidence of association (p(repl) <0.05). FUT2 at chromosome 19q13 (rs602662; p(comb)=1.9 × 10(-6), rs281377; p(comb)=2.1 × 10(-6) and rs601338; p(comb)=2.7 × 10(-6)) is notable due to its implication in altered susceptibility to infectious agents. We found that FUT2 secretor status and genotype defined by rs601338 significantly influence biliary microbial community composition in PSC patients. CONCLUSIONS We identify multiple new PSC risk loci by extended analysis of a PSC GWAS. FUT2 genotype needs to be taken into account when assessing the influence of microbiota on biliary pathology in PSC.

Three ulcerative colitis susceptibility loci are associated with primary sclerosing cholangitis and indicate a role for IL2, REL and CARD9

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by inflammation and fibrosis of the bile ducts. Both environmental and genetic factors contribute to its pathogenesis. To further clarify its genetic background, we investigated susceptibility loci recently identified for ulcerative colitis (UC) in a large cohort of 1,186 PSC patients and 1,748 controls. Single nucleotide polymorphisms (SNPs) tagging 13 UC susceptibility loci were initially genotyped in 854 PSC patients and 1,491 controls from Benelux (331 cases, 735 controls), Germany (265 cases, 368 controls), and Scandinavia (258 cases, 388 controls). Subsequently, a joint analysis was performed with an independent second Scandinavian cohort (332 cases, 257 controls). SNPs at chromosomes 2p16 (P‐value 4.12 × 10−4), 4q27 (P‐value 4.10 × 10−5), and 9q34 (P‐value 8.41 × 10−4) were associated with PSC in the joint analysis after correcting for multiple testing. In PSC patients without inflammatory bowel disease (IBD), SNPs at 4q27 and 9q34 were nominally associated (P < 0.05). We applied additional in silico analyses to identify likely candidate genes at PSC susceptibility loci. To identify nonrandom, evidence‐based links we used GRAIL (Gene Relationships Across Implicated Loci) analysis showing interconnectivity between genes in six out of in total nine PSC‐associated regions. Expression quantitative trait analysis from 1,469 Dutch and UK individuals demonstrated that five out of nine SNPs had an effect on cis‐gene expression. These analyses prioritized IL2, CARD9, and REL as novel candidates. Conclusion: We have identified three UC susceptibility loci to be associated with PSC, harboring the putative candidate genes REL, IL2, and CARD9. These results add to the scarce knowledge on the genetic background of PSC and imply an important role for both innate and adaptive immunological factors. (HEPATOLOGY 2011;)

Immune-mediated diseases in primary sclerosing cholangitis

BACKGROUND Primary sclerosing cholangitis is a chronic cholestatic liver disease. An immune aetiology is suggested by associations between PSC and inflammatory bowel disease. Data on concomitant prevalence of other immune-mediated diseases is limited. AIM To assess the prevalence of concomitant immune-mediated diseases and the impact on disease outcome in PSC. METHODS We included 241 patients and retrospectively reviewed medical charts. RESULTS Altogether 172 (71.4%) patients had concomitant immune-mediated disease, including IBD (149, 61.8%), autoimmune hepatitis (15, 6.2%) and other immune-mediated diseases (47, 19.5%). Thirty nine patients (22.7%) had more than one immune-mediated disease other than PSC. Most frequent extrahepatic non-IBD immune-mediated diseases were sarcoidosis, thyroid disease, and type I diabetes mellitus. Age at PSC diagnosis was lower in patients with IBD. In patients with other immune-mediated diseases than autoimmune hepatitis or IBD, age at PSC diagnosis was higher. Younger age at diagnosis and concomitant IBD related to longer survival till death or liver transplantation. CONCLUSIONS In a large PSC population, a high prevalence of concomitant immune-mediated diseases was found. IBD occurred more often in early-acquired PSC, and the other immune-mediated diseases more often in later-acquired PSC. No effect on outcome was found for non-IBD immune mediated disease.

Implementation and evaluation of a nurse-centered computerized potassium regulation protocol in the intensive care unit - a before and after analysis

BackgroundPotassium disorders can cause major complications and must be avoided in critically ill patients. Regulation of potassium in the intensive care unit (ICU) requires potassium administration with frequent blood potassium measurements and subsequent adjustments of the amount of potassium administrated. The use of a potassium replacement protocol can improve potassium regulation. For safety and efficiency, computerized protocols appear to be superior over paper protocols. The aim of this study was to evaluate if a computerized potassium regulation protocol in the ICU improved potassium regulation.MethodsIn our surgical ICU (12 beds) and cardiothoracic ICU (14 beds) at a tertiary academic center, we implemented a nurse-centered computerized potassium protocol integrated with the pre-existent glucose control program called GRIP (Glucose Regulation in Intensive Care patients). Before implementation of the computerized protocol, potassium replacement was physician-driven. Potassium was delivered continuously either by central venous catheter or by gastric, duodenal or jejunal tube. After every potassium measurement, nurses received a recommendation for the potassium administration rate and the time to the next measurement. In this before-after study we evaluated potassium regulation with GRIP. The attitude of the nursing staff towards potassium regulation with computer support was measured with questionnaires.ResultsThe patient cohort consisted of 775 patients before and 1435 after the implementation of computerized potassium control. The number of patients with hypokalemia (<3.5 mmol/L) and hyperkalemia (>5.0 mmol/L) were recorded, as well as the time course of potassium levels after ICU admission. The incidence of hypokalemia and hyperkalemia was calculated. Median potassium-levels were similar in both study periods, but the level of potassium control improved: the incidence of hypokalemia decreased from 2.4% to 1.7% (P < 0.001) and hyperkalemia from 7.4% to 4.8% (P < 0.001). Nurses indicated that they considered computerized potassium control an improvement over previous practice.ConclusionsComputerized potassium control, integrated with the nurse-centered GRIP program for glucose regulation, is effective and reduces the prevalence of hypo- and hyperkalemia in the ICU compared with physician-driven potassium regulation.

Extraintestinal manifestations and complications in inflammatory bowel disease: from shared genetics to shared biological pathways.

Background:The clinical presentation of the inflammatory bowel diseases (IBD) is extremely heterogenous and is characterized by various extraintestinal manifestations and complications (EIM). Increasing genetic insight for IBD and EIM shows multiple shared susceptibility loci. We hypothesize that, next to these overlapping genetic risk loci, distinct disease pathways are shared between IBD and EIM. Methods:The overlapping genetic risk loci for IBD and its EIM were searched in literature. We assessed shared disease pathways by performing an extensive pathway analysis by protein–protein interaction and cotranscriptional analysis, using both publicly available and newly developed databases. Results:Reliable genetic data were available for primary sclerosing cholangitis, ankylosing spondylitis, decreased bone mineral density, colorectal carcinoma, gallstones, kidney stones, and deep venous thrombosis. We found an extensive overlap in genetic risk loci, especially for IBD and primary sclerosing cholangitis and ankylosing spondylitis. We identified 370 protein–protein interactions, of which 108 are statistically specific. We identified 446 statistically specific cotranscribed gene pairs. The interactions are shown to cluster in specific biological pathways. Conclusions:We show that the pathogenetic overlap between IBD and its EIM extends beyond shared risk genes to distinctive shared biological pathways. We define genetic background as a risk factor for IBD-EIM alongside known mechanisms such as malabsorption and medication. Clustering patients based on distinctive pathways may enable stratification of patients to predict development of EIM.

Association of Crohn's disease-associated NOD2 variants with intestinal failure requiring small bowel transplantation and clinical outcomes

In the past decade intestinal transplantation has evolved to a viable option in the treatment of short bowel syndrome, especially for patients who have developed life-threatening complications attributable to their intestinal failure and/or long-term total parental nutrition therapy.1 Technical improvements, novel immunosuppressive agents and increased clinical experience have contributed to an improvement in intestineal transplant graft and patient survival. One-year graft and patient survival are nowadays both estimated at 80%.2 3 Despite these recent advances, rejection resulting in failure of the graft still remains a problem causing significant patient morbidity and mortality. Identifying involved pathogenetic mechanisms might make it possible to predict or eventually prevent intestinal graft failure or rejection. We would like to respond to the interesting study by Fishbein et al recently published in this journal.4 The authors point out the …

MMP-2 is a disease-modifying gene in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disease of the bile ducts, frequently necessitating orthotopic liver transplantation (OLT), often accompanied by inflammatory bowel disease (IBD). Matrix metalloproteinases (MMPs) are associated with fibrotic diseases caused by the involvement in tissue remodelling.

The impact of a reduced dose of dexamethasone on glucose control after coronary artery bypass surgery

BackgroundIntensive insulin therapy to maintain normoglycemia after cardiac surgery reduces morbidity and mortality. We investigated the magnitude and duration of hyperglycemia caused by dexamethasone administered after cardiopulmonary bypass.MethodsA single-center before-after cohort study was performed. All consecutive patients undergoing coronary artery bypass grafting with cardiopulmonary bypass during a 6-month period were included. Insulin administration was guided by a sliding scale protocol. Halfway the observation period, the dexamethasone protocol was changed. The single dose (1D) group received a pre-operative dose of dexamethasone of 1 mg/kg. The double dose group (2D) received an additional dose of 0.5 mg/kg of dexamethasone post-operatively at ICU admission.ResultsWe included 116 patients in the 1D group and 158 patients in the 2D group. There were no significant baseline differences between the groups. Median Euroscore was 5. In univariable analysis, the glucose level was different between groups 1D and 2D at 4, 6, 9, 12 and 24 hours after ICU admission (all p < 0.001). Insulin infusion was higher in the 1D group. Corrected for insulin dose in multivariable linear analysis, the difference in glucose between the 1D and 2D groups was 1.5 mmol/L (95% confidence interval 1.0–2.0, p < 0.001) 12 hours after ICU admission.ConclusionDexamethasone exerts a hyperglycemic effect in cardiac surgery patients. Patients receiving high-dose corticosteroid therapy should be monitored and treated more intensively for hyperglycemic episodes.

Recipient's Genetic R702W NOD2 Variant Is Associated with an Increased Risk of Bacterial Infections after Orthotopic Liver Transplantation

Introduction Orthotopic liver transplantation (OLT) is accompanied by a significant postoperative infection risk. Immunosuppression to prevent rejection increases the susceptibility to infections, mainly by impairing the adaptive immune system. Genetic polymorphisms in the lectin complement pathway of the donor have recently been identified as important risk determinants of clinically significant bacterial infection (CSI) after OLT. Another genetic factor involved in innate immunity is NOD2, which was reported to be associated with increased risk of spontaneous bacterial peritonitis in cirrhotic patients. Methods We assessed association of three genetic NOD2 variants (R702W, G908R and 3020insC) with increased risk of CSI after OLT. 288 OLT recipient-donor pairs from two tertiary referral centers were genotyped for the three NOD2 variants. The probability of CSI in relation to NOD2 gene variants was determined with cumulative incidence curves and log-rank analysis. Results The R702W NOD2 variant in the recipient was associated with CSI after OLT. Eight out of 15 (53.3%) individuals with a mutated genotype compared to 80/273 (29.3%) with wild type genotype developed CSI (p=0.027, univariate cox regression), illustrated by a higher frequency of CSI after OLT over time (p=0.0003, log rank analysis). Multivariate analysis (including the donor lectin complement pathway profile) showed independence of this R702W NOD2 association from other risk factors (HR 2.0; p=0.04). The other NOD2 variants, G908R and 3020insC, in the recipient were not associated with CSI. There was no association with CSI after OLT for any of the NOD2 variants in the donor. Conclusion The mutated NOD2 R702W genotype in the recipient is independently associated with an increased risk of bacterial infections after liver transplantation, indicating a predisposing role for this genetic factor impairing the recipient’s innate immune system.

Novel Susceptibility Loci for Primary Sclerosing Cholangitis Identified by Genome-Wide Association and Replication Analysis

Idiosyncratic drug-induced liver injury (DILI) is a leading cause of morbidity and mortality due to medication use yet is poorly studied, in part, due to its low incidence in the general population. Identification of genetic variants associated with these uncommon and difficult to diagnose adverse events could provide clues to underlying mechanisms. Hypothesis: Common genetic variants exist that contribute to DILI susceptibility from multiple drugs. Methods: DNA obtained from 783 individuals of European ancestry who experienced DILI attributed to >200 individual drugs were genotypedwith the Illumina 1Mor 1Mduo beadchip. Source of DNA samples included the following DILI registries: DILIN (401), DILIGEN (242), EUDRAGENE (89), and Malaga (51). Genome Wide Association (GWA) was performed using population controls (n=3001). Potential associations were tested for replication in 190 independent cases from DILIN. Results: GWA revealed a strong association within the MHC region (p 108), which did not replicate in validation cohorts composed of sufficient cases due to the same drug or class. Conclusion: Our replicated association between hepatocellular DILI and STAT4 supports the emerging role of the immune system in DILI susceptibility and suggests that common genetic variation may contribute to DILI susceptibility from multiple drugs. However, the generally negative GWA results suggest that there may be a preponderance of drug-specific genetic risk factors and/or rare genetic variation underlying DILI susceptibility. Therefore, we have begun whole exome and whole genome sequencing of DILI cases caused by the most frequent drugs in our cohorts in search of rarer, high-penetrance drug-specific risk factors.