Jean Paul Achkar

Ulcerative colitis-risk loci on chromosomes 1p36 and 12q15 found by genome-wide association study

Ulcerative colitis is a chronic inflammatory disease of the colon that presents as diarrhea and gastrointestinal bleeding. We performed a genome-wide association study using DNA samples from 1,052 individuals with ulcerative colitis and preexisting data from 2,571 controls, all of European ancestry. In an analysis that controlled for gender and population structure, ulcerative colitis loci attaining genome-wide significance and subsequent replication in two independent populations were identified on chromosomes 1p36 (rs6426833, combined P = 5.1 × 10−13, combined odds ratio OR = 0.73) and 12q15 (rs1558744, combined P = 2.5 × 10−12, combined OR = 1.35). In addition, combined genome-wide significant evidence for association was found in a region spanning BTNL2 to HLA-DQB1 on chromosome 6p21 (rs2395185, combined P = 1.0 × 10−16, combined OR = 0.66) and at the IL23R locus on chromosome 1p31 (rs11209026, combined P = 1.3 × 10−8, combined OR = 0.56; rs10889677, combined P = 1.3 × 10−8, combined OR = 1.29).

ATG16L1 and NOD2 Interact in an Autophagy-Dependent Antibacterial Pathway Implicated in Crohn's Disease Pathogenesis

BACKGROUND & AIMS The identification of numerous genes that confer susceptibility to Crohns disease (CD) indicates that this complex disease might arise from alterations in several genes with related functions. We examined the functional interaction between the CD risk genes ATG16L1 and NOD2 to identify an autophagy-dependent pathway that is altered by disease-associated variants. METHODS We assessed Nod2 signaling and autophagy activation in response to muramyl dipeptide (MDP) by immunoblot, confocal microscopy, flow cytometry, reporter gene, and gentamicin protection assays in human epithelial cell lines and primary human macrophages and dendritic cells from healthy individuals. The requirement of Nod2 and ATG16L1 expression and the effects of CD-associated variants in MDP-stimulated autophagy and Nod2-dependent signaling were assessed in cell lines manipulated by RNA interference, inhibitors, or ATG16L1 or NOD2 variants and in primary macrophages and dendritic cells from healthy genotyped donors. RESULTS MDP stimulation of epithelial cells, macrophages, and dendritic cells activated autophagy and nuclear factor κB and mitogen-activated protein kinase signaling; it also increased killing of Salmonella. These responses depended on ATG16L1 and Nod2 expression and were impaired by CD-associated NOD2 variants. Nod2-dependent signaling was not impaired in cells with the ATG16L1 T300A genotype, which is associated with CD. However, the ATG16L1 T300A variant blocked the increase in MDP-mediated killing of Salmonella only in epithelial cell lines and not primary macrophages or dendritic cells. CONCLUSIONS ATG16L1 and NOD2 are components of an autophagy-mediated antibacterial pathway that is altered in a cell- and function-specific manner by CD-associated mutations.

A Randomized Clinical Trial of Ciprofloxacin and Metronidazole to Treat Acute Pouchitis

Metronidazole is effective for the treatment of acute pouchitis after ileal pouch–anal anastomosis, but it has not been directly compared with other antibiotics. This randomized clinical trial was designed to compare the effectiveness and side effects of ciprofloxacin and metronidazole for treating acute pouchitis. Acute pouchitis was defined as a score of 7 or higher on the 18-point Pouchitis Disease Activity Index (PDAI) and symptom duration of 4 weeks or less. Sixteen patients were randomized to a 2-week course of ciprofloxacin 1,000 mg/d (n = 7) or metronidazole 20 mg/kg/d (n = 9). Clinical symptoms, endoscopic findings, and histologic features were assessed before and after therapy. Both ciprofloxacin and metronidazole produced a significant reduction in the total PDAI score as well as in the symptom, endoscopy, and histology subscores. Ciprofloxacin lowered the PDAI score from 10.1 ± 2.3 to 3.3 ± 1.7 (p = 0.0001), whereas metronidazole reduced the PDAI score from 9.7 ± 2.3 to 5.8 ± 1.7 (p = 0.0002). There was a significantly greater reduction in the ciprofloxacin group than in the metronidazole group in terms of the total PDAI (6.9 ± 1.2 versus 3.8 ± 1.7; p = 0.002), symptom score (2.4 ± 0.9 versus 1.3 ± 0.9; p = 0.03), and endoscopic score (3.6 ± 1.3 versus 1.9 ± 1.5; p = 0.03). None of patients in the ciprofloxacin group experienced adverse effects, whereas three patients in the metronidazole group (33%) developed vomiting, dysgeusia, or transient peripheral neuropathy. Both ciprofloxacin and metronidazole are effective in treating acute pouchitis with significant reduction of the PDAI scores. Ciprofloxacin produces a greater reduction in the PDAI and a greater improvement in symptom and endoscopy scores, and is better tolerated than metronidazole. Ciprofloxacin should be considered as one of the first-line therapies for acute pouchitis.

MDR1 Ala893 Polymorphism Is Associated with Inflammatory Bowel Disease

Crohn disease (CD) and ulcerative colitis (UC) are overlapping chronic inflammatory bowel diseases (IBDs). Suggestive evidence for linkage at chromosome 7q has been reported for both CD and UC. Contained within this region is the gene for MDR1 (multidrug resistance), a membrane transport protein for which human polymorphisms have been reported in Ala893Ser/Thr and C3435T that alter pharmacokinetic profiles for a variety of drugs. Because mdr1 knockout mice spontaneously develop colitis, exonic regions were resequenced and tested for IBD association in a large, multicenter North American cohort. Two missense mutations, Asn21Asp and Ala893Ser/Thr, as well as the expression-associated polymorphism C3435T, described elsewhere, were genotyped in the entire cohort. Significant association of Ala893 with IBD was observed by both case-control analysis (P=.002) and the pedigree disequilibrium test (PDT [P=.00020-.00030]) but not for the Asn21Asp or C3435T polymorphisms. Significant association by PDT was observed within the subset with CD (P=.0014-.00090), with similar, nonsignificant trends in a smaller subset with UC. The Ala893Ser/Thr variant is triallelic, and the associated, common allele is Ala893, with undertransmission of the 893Ser (common) and the 893Thr (rare) variants. The Ala893 variant has decreased activity compared with the 893Ser variant; therefore, the association with human IBD is consistent with the murine model of mdr1 deficiency. Taken together, these data support the association of the common Ala893 polymorphism with IBD specifically and, more broadly, provides additional support for its contribution to interindividual pharmacogenetic variation.

An evidence-based systematic review on medical therapies for inflammatory bowel disease.

Crohn ’ s disease (CD) and ulcerative colitis (UC) are chronic infl ammatory disorders of the gastrointestinal tract. Collectively they are termed infl ammatory bowel disease (IBD) and it is estimated that 1.5 million Americans ( 1 ) suff er from UC and CD. Th eir etiologies are unknown, although both are thought to arise from a disordered immune response to the gut contents in genetically predisposed individuals ( 1 ). Th e characteristics of the infl ammatory response are diff erent, with CD typically causing transmural infl ammation and occasionally associated with granulomas, whereas in UC the infl ammation is usually confi ned to the mucosa. Both UC and CD exhibit a relapsing and remitting course and there is a signifi cant, oft en dramatic, reduction in quality of life during exacerbations of the disease ( 2 ). Th is has an impact on psychological health, with active IBD patients experiencing greater levels of distress and feelings of lack of sense of self-control compared with the normal population and patients with inactive IBD ( 3,4 ).

Defining complex contributions of NOD2/CARD15 gene mutations, age at onset, and tobacco use on Crohn's disease phenotypes

BackgroundMultiple factors, particularly IBD family history, tobacco use, age at diagnosis and recently, NOD2 mutant genotypes may influence Crohns disease (CD) heterogeneity. MethodsWe performed a multicenter retrospective record analysis of 275 unrelated patients with CD. Age at diagnosis, IBD family history, Jewish ethnicity, tobacco use at diagnosis, surgical history, disease site and clinical behavior were correlated with genotypes for NOD2 mutations, and all risk factors were assessed for independent influence on outcomes of disease site, behavior and surgery free survival. ResultsRisk of ileal disease was increased for CD patients with two NOD2 mutations (Odds Ratio, O.R. 10.1), a smoking history (O.R. 2.25 per pack per day at diagnosis) or a younger age at diagnosis (O.R. 0.97 per each increased year). Presence of ileal disease (O.R. 4.8) and carrying one or two NOD2 mutations (O.R. 1.9 and 3.5, respectively) were independent risk factors for stricturing or non-perianal fistulizing behavior. Ileal disease, youthful onset and smoking at diagnosis (but not NOD2 mutations) were risk factors for early surgery. ConclusionsCarrying two NOD2 mutations predicts youthful onset, ileal disease involvement, and development of stricturing or non-perianal fistulizing complications. Smoking and early onset independently influence ileal site and time to surgery.

Modified Pouchitis Disease Activity Index A Simplified Approach to the Diagnosis of Pouchitis

AbstractPURPOSE: Pouchitis is the most common complication of ileal pouch-anal anastomosis for ulcerative colitis. Our previous study suggested that symptoms alone are not reliable for the diagnosis of pouchitis. The most commonly used diagnostic instrument is the 18-point pouchitis disease activity index consisting of three principal component scores: symptom, endoscopy, and histology. Despite its popularity, the pouchitis disease activity index has mainly been a research tool because of costs of endoscopy (especially with histology), complexity in calculation, and time delay in determining histology scores. It is not known whether pouch endoscopy without biopsy can reliably diagnose pouchitis in symptomatic patients. The aim of the present study was to determine whether omitting histologic evaluation from the pouchitis disease activity index significantly affects the sensitivity and specificity of diagnostic criteria for pouchitis. METHODS: Ulcerative colitis patients with an ileal pouch-anal anastomosis and symptoms suggestive of pouchitis were evaluated. Patients with chronic refractory pouchitis and Crohn’s disease were excluded. Patients with pouchitis disease activity index scores of seven or more were diagnosed as having pouchitis. Different diagnostic criteria were compared on the basis of the pouchitis disease activity index component scores. Nonparametric receiver-operating-characteristic curves were used to measure proposed pouchitis scores’ diagnostic accuracy compared with diagnosis from the pouchitis disease activity index. The receiver-operating-characteristic area under the curve measured how much these diagnostic strategies differed from each other. RESULTS: Fifty-eight consecutive symptomatic patients were enrolled; 32 (55 percent) patients were diagnosed with pouchitis. With the use of the pouchitis disease activity index as a criterion standard, the use of only symptom and endoscopy scores (modified pouchitis disease activity index) produced an area under the curve of 0.995. Establishing a cut-point of five or more for diseased patients resulted in a sensitivity equal to 97 percent and specificity equal to 100 percent. CONCLUSIONS: Diagnosis based on the modified pouchitis disease activity index offers similar sensitivity and specificity when compared with the pouchitis disease activity index for patients with acute or acute relapsing pouchitis. Omission of endoscopic biopsy and histology from the standard pouchitis disease activity index would simplify pouchitis diagnostic criteria, reduce the cost of diagnosis, and avoid delay associated with determining histology score, while providing equivalent sensitivity and specificity.

Irritable pouch syndrome: a new category of diagnosis for symptomatic patients with ileal pouch-anal anastomosis

OBJECTIVE: Pouchitis often is diagnosed based on symptoms alone. However, increased stool frequency, urgency, and abdominal pain could be due to a condition resembling irritable bowel syndrome. This study was designed to assess the etiology of bowel symptoms using the Pouchitis Disease Activity Index (PDAI). METHODS: Symptoms, endoscopy, and histology were assessed in 61 consecutive symptomatic patients with ulcerative colitis after ileal pouch–anal anastomosis. Pouchitis was defined as a PDAI score of 7, cuffitis was defined as endoscopic and histological inflammation of the rectal cuff and no inflammation of the pouch, and irritable pouch syndrome (IPS) was defined as symptoms with a PDAI of 7 and the absence of cuffitis. RESULTS: Thirty-one patients (50.8%) had pouchitis, four (6.5%) had cuffitis, and 26 (42.6%) had IPS. Demographics were similar in the three groups. Increased stool frequency, urgency, and abdominal cramps were the most common symptoms in the three groups. Rectal bleeding was seen only in cuffitis ( p 0.001). No patient in the three groups had fever. Twenty-seven patients (87.1%) with pouchitis responded to a 2-wk course of ciprofloxacin or metronidazole with a reduction in PDAI scores of 3. All four patients with cuffitis responded to topical hydrocortisone or mesalamine with a reduction in the PDAI symptom component score of 1. Twelve patients with IPS (46.2%) responded to antidiarrheal, anticholinergic, and/or antidepressant therapies with a reduction in the PDAI symptom component score of 1, whereas the remaining patients had persistent symptoms despite therapy. CONCLUSIONS: A substantial number of symptomatic patients after ileal pouch–anal anastomosis do not meet the diagnostic criteria for either pouchitis or cuffitis and have been classified as having IPS. There is an overlap of symptoms among patients with pouchitis, cuffitis, and IPS, and endoscopic evaluation can differentiate among these groups. Distinction between these three groups has therapeutic implications. (Am J Gastroenterol 2002;97:972–977.

Efficacy of 5-Aminosalicylates in Ulcerative Colitis: Systematic Review and Meta-Analysis

OBJECTIVES:The efficacy of 5-aminosalicylic acids (5-ASAs) in ulcerative colitis (UC) has been studied previously in meta-analyses. However, several randomized controlled trials (RCTs) have been published recently, and no previous meta-analysis has studied the effect of 5-ASA dosage used.METHODS:MEDLINE, EMBASE, and the Cochrane central register of controlled trials were searched (through December 2010). Eligible trials recruited adults with active or quiescent UC, comparing different doses of 5-ASAs with themselves or placebo. Dichotomous data were pooled to obtain relative risk (RR) of failure to achieve remission in active UC, and RR of relapse of disease activity in quiescent UC, with a 95% confidence interval (CI). The number needed to treat (NNT) was calculated from the reciprocal of the risk difference.RESULTS:The search identified 3,061 citations, and 37 RCTs were eligible. Of these, 11 compared 5-ASA with placebo in active UC remission, with the RR of no remission with 5-ASAs of 0.79 (95% CI 0.73–0.85; NNT=6). Doses of ≥2.0 g/day were more effective than <2.0 g/day for remission (RR=0.91; 95% CI 0.85–0.98). There were 11 RCTs comparing 5-ASAs with placebo in preventing relapse of quiescent UC, with the RR of relapse of 0.65 (95% CI 0.55–0.76; NNT=4). Doses of ≥2.0 g/day appeared more effective than <2.0 g/day for preventing relapse (RR=0.79; 95% CI 0.64–0.97).CONCLUSIONS:5-ASAs are highly effective for inducing remission and preventing relapse in UC. Evidence suggests that doses of ≥2.0 g/day have greater efficacy, although doses >2.5 g/day do not appear to lead to higher remission rates.

Efficacy of 5-Aminosalicylates in Crohn's Disease: Systematic Review and Meta-Analysis

OBJECTIVES:Crohns disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract. Evidence for treatment with 5-aminosalicylic acid (5-ASA) drugs is conflicting. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to examine this issue.METHODS:MEDLINE, EMBASE, and the Cochrane central register of controlled trials were searched (through December 2010). Authors of studies were contacted to provide additional information on trials where required, and experts in the field were contacted to identify unpublished studies. Eligible trials recruited adults with active or quiescent CD and compared 5-ASAs with placebo, or no treatment. Dichotomous data were pooled to obtain relative risk (RR) of failure to achieve remission in active CD, and RR of relapse of disease activity in quiescent CD, with a 95% confidence interval (CI). The number needed to treat (NNT) was calculated from the reciprocal of the risk difference.RESULTS:The search identified 3,061 citations. Twenty-two RCTs were eligible. Six RCTs compared 5-ASA with placebo in active CD remission. There was a trend towards a benefit with sulfasalazine over placebo (two RCTs, RR of failure to achieve remission=0.83; 95% CI=0.69–1.00), but no definite benefit of mesalamine over placebo (four RCTs, RR=0.91; 95% CI=0.77–1.06). Neither sulfasalazine nor mesalamine were effective in preventing quiescent CD relapse, but in a per protocol analysis mesalamine appeared to reduce risk of relapse (RR=0.79; 95% CI=0.66–0.95, NNT=13).CONCLUSIONS:The role of 5-ASAs in inducing remission of active CD and preventing relapse of quiescent CD remains uncertain, and more RCTs are required.