Denis Franchimont

Genome-wide association defines more than 30 distinct susceptibility loci for Crohn's disease

Several risk factors for Crohns disease have been identified in recent genome-wide association studies. To advance gene discovery further, we combined data from three studies on Crohns disease (a total of 3,230 cases and 4,829 controls) and carried out replication in 3,664 independent cases with a mixture of population-based and family-based controls. The results strongly confirm 11 previously reported loci and provide genome-wide significant evidence for 21 additional loci, including the regions containing STAT3, JAK2, ICOSLG, CDKAL1 and ITLN1. The expanded molecular understanding of the basis of this disease offers promise for informed therapeutic development.

Genome-wide meta-analysis increases to 71 the number of confirmed Crohn's disease susceptibility loci

We undertook a meta-analysis of six Crohns disease genome-wide association studies (GWAS) comprising 6,333 affected individuals (cases) and 15,056 controls and followed up the top association signals in 15,694 cases, 14,026 controls and 414 parent-offspring trios. We identified 30 new susceptibility loci meeting genome-wide significance (P < 5 × 10−8). A series of in silico analyses highlighted particular genes within these loci and, together with manual curation, implicated functionally interesting candidate genes including SMAD3, ERAP2, IL10, IL2RA, TYK2, FUT2, DNMT3A, DENND1B, BACH2 and TAGAP. Combined with previously confirmed loci, these results identify 71 distinct loci with genome-wide significant evidence for association with Crohns disease.

Deficient host-bacteria interactions in inflammatory bowel disease? The toll-like receptor (TLR)-4 Asp299gly polymorphism is associated with Crohn’s disease and ulcerative colitis

Background and aims: Elicitation of an innate immune response to bacterial products is mediated through pattern recognition receptors (PRRs) such as the toll-like receptors (TLRs) and the NODs. The recently characterised Asp299Gly polymorphism in the lipopolysaccharide (LPS) receptor TLR4 is associated with impaired LPS signalling and increased susceptibility to Gram negative infections. We sought to determine whether this polymorphism was associated with Crohn’s disease (CD) and/or ulcerative colitis (UC). Methods: Allele frequencies of the TLR4 Asp299Gly polymorphism and the three NOD2/CARD15 polymorphisms (Arg702Trp, Gly908Arg, and Leu1007fsinsC) were assessed in two independent cohorts of CD patients (cohort 1, n = 334; cohort 2, n = 114), in 163 UC patients, and in 140 controls. A transmission disequilibrium test (TDT) was then performed on 318 inflammatory bowel disease (IBD) trios. Results: The allele frequency of the TLR4 Asp299Gly polymorphism was significantly higher in CD (cohort 1: 11% v 5%, odds ratio (OR) 2.31 (95% confidence interval (CI) 1.28–4.17), p = 0.004; and cohort 2: 12% v 5%, OR 2.45 (95% CI 1.24–4.81), p = 0.007) and UC patients (10% v 5%, OR 2.05 (95% CI 1.07–3.93), p = 0.027) compared with the control population. A TDT on 318 IBD trios demonstrated preferential transmission of the TLR4 Asp299Gly polymorphism from heterozygous parents to affected children (T/U: 68/34, p = 0.01). Carrying polymorphisms in both TLR4 and NOD2 was associated with a genotype relative risk (RR) of 4.7 compared with a RR of 2.6 and 2.5 for TLR4 and NOD2 variants separately. Conclusion: We have reported on a novel association of the TLR4 Asp299Gly polymorphism with both CD and UC. This finding further supports the genetic influence of PRRs in triggering IBD.

Tumour necrosis factor (TNF) gene polymorphism influences TNF-α production in lipopolysaccharide (LPS)-stimulated whole blood cell culture in healthy humans

TNF‐α is involved in infectious and immuno‐inflammatory diseases. Different individuals may have different capacities for TNF‐α production. This might determine a predisposition to develop some complications or phenotypes of these diseases. The aims of our study were to assess the inter‐individual variability of TNF‐α production and to correlate this variability to a single base pair polymorphism located at position −308 in TNF gene. We studied 62 healthy individuals. TNF‐α production after LPS stimulation was evaluated using a whole blood cell culture model. The TNF gene polymorphism was studied by an allele‐specific polymerase chain reaction. Other cytokines produced in the culture, soluble CD14 concentrations and expression of CD14 on blood cells were also measured. Among the 62 individuals, 57 were successfully genotyped. There were 41 TNF1 homozygotes and 16 TNF1/TNF2 heterozygotes. TNF‐α production after LPS stimulation of whole blood cell culture was higher among TNF2 carriers than among TNF1 homozygotes (929 pg/ml (480–1473 pg/ml) versus 521 pg/ml (178–1307 pg/ml); P < 0.05). This difference was even more significant after correction of TNF‐α production for CD14 expression on blood cells. In conclusion, the single base pair polymorphism at position −308 in the TNF gene may influence TNF‐α production in healthy individuals.

Novel Crohn disease locus identified by genome-wide association maps to a gene desert on 5p13.1 and modulates expression of PTGER4

To identify novel susceptibility loci for Crohn disease (CD), we undertook a genome-wide association study with more than 300,000 SNPs characterized in 547 patients and 928 controls. We found three chromosome regions that provided evidence of disease association with p-values between 10−6 and 10−9. Two of these (IL23R on Chromosome 1 and CARD15 on Chromosome 16) correspond to genes previously reported to be associated with CD. In addition, a 250-kb region of Chromosome 5p13.1 was found to contain multiple markers with strongly suggestive evidence of disease association (including four markers with p < 10−7). We replicated the results for 5p13.1 by studying 1,266 additional CD patients, 559 additional controls, and 428 trios. Significant evidence of association (p < 4 × 10−4) was found in case/control comparisons with the replication data, while associated alleles were over-transmitted to affected offspring (p < 0.05), thus confirming that the 5p13.1 locus contributes to CD susceptibility. The CD-associated 250-kb region was saturated with 111 SNP markers. Haplotype analysis supports a complex locus architecture with multiple variants contributing to disease susceptibility. The novel 5p13.1 CD locus is contained within a 1.25-Mb gene desert. We present evidence that disease-associated alleles correlate with quantitative expression levels of the prostaglandin receptor EP4, PTGER4, the gene that resides closest to the associated region. Our results identify a major new susceptibility locus for CD, and suggest that genetic variants associated with disease risk at this locus could modulate cis-acting regulatory elements of PTGER4.

Gene profiling reveals unknown enhancing and suppressive actions of glucocorticoids on immune cells

Glucocorticoids continue to be the ma‐jor immunomodulatory agents used in clinical medicine today. However, their actions as anti‐inflammatory and immunosuppressive drugs are both beneficial and del‐eterious. We analyzed the effect of glucocorticoids on the gene expression profile of peripheral blood mono‐nuclear cells from healthy donors. DNA microarray analysis combined with quantitative TaqMan PCR and flow cytometry revealed that glucocorticoids induced the expression of chemokine, cytokine, and comple‐ment family members as well as of newly discovered innate immune‐related genes, including scavenger and Toll‐like receptors. In contrast, glucocorticoids re‐pressed the expression of adaptive immune‐related genes. Simultaneous inhibitory and stimulatory effects of glucocorticoids were found on inflammatory T helper subsets and apoptosis‐related gene clusters. In cells activated by T cell receptor cross‐linking, glucocor‐ticoids down‐regulated the expression of specific genes that were previously up‐regulated in resting cells, sug‐gesting a potential new mechanism by which they exert positive and negative effects. Considering the broad and continuously renewed interest in glucocorticoid therapy, the profiles we describe here will be useful in designing more specific and efficient treatment strate‐gies.— Galon, J., Franchimont, D., Hiroi, N., Frey, G., Boettner, A., Ehrhart‐Bornstein, M., O’Shea, J. J., Chrousos, G. P., Bornstein, S. R. Gene profiling reveals unknown enhancing and suppressive actions of glucocorticoids on immune cells. FASEB J. 16, 61–71 (2002)

Common variants in the NLRP3 region contribute to Crohn's disease susceptibility

We used a candidate gene approach to identify a set of SNPs, located in a predicted regulatory region on chromosome 1q44 downstream of NLRP3 (previously known as CIAS1 and NALP3) that are associated with Crohns disease. The associations were consistently replicated in four sample sets from individuals of European descent. In the combined analysis of all samples (710 father-mother-child trios, 239 cases and 107 controls), these SNPs were strongly associated with risk of Crohns disease (Pcombined = 3.49 × 10−9, odds ratio = 1.78, confidence interval = 1.47–2.16 for rs10733113), reaching a level consistent with the stringent significance thresholds imposed by whole-genome association studies. In addition, we observed significant associations between SNPs in the associated regions and NLRP3 expression and IL-1β production. Mutations in NLRP3 are known to be responsible for three rare autoinflammatory disorders. These results suggest that the NLRP3 region is also implicated in the susceptibility of more common inflammatory diseases such as Crohns disease.

Overview of the Actions of Glucocorticoids on the Immune Response: A Good Model to Characterize New Pathways of Immunosuppression for New Treatment Strategies

Abstract: Glucocorticoids have been used for over 50 years in the treatment of inflammatory and autoimmune diseases and in preventing graft rejection. Today, knowledge of their molecular, cellular, and pharmacological properties allows a better understanding of glucocorticoid‐mediated immunosuppression. Glucocorticoids exert both negative and positive effects with a dynamic and bi‐directional spectrum of activities on various limbs and components of the immune response. They modulate genes involved in the priming of the innate immune response, while their actions on the adaptive immune response are to suppress cellular (Th1) immunity and promote humoral (Th2) immunity. Interestingly, glucocorticoids can also induce tolerance to specific antigens by influencing dendritic cell maturation and function and promoting the development of regulatory high IL‐10‐producing T cells. The ex vivo therapeutic use of glucocorticoids could therefore represent an adjuvant treatment to cell therapy in autoimmune diseases, avoiding the long‐term deleterious adverse effects of glucocorticoids. Thus, the panoramic view of glucocorticoid actions on the immune system provides an interesting model for characterizing important biological pathways of immunosuppression.

Ciclosporin versus infliximab in patients with severe ulcerative colitis refractory to intravenous steroids: a parallel, open-label randomised controlled trial

BACKGROUND Ciclosporin and infliximab are potential rescue treatments to avoid colectomy in patients with acute severe ulcerative colitis refractory to intravenous corticosteroids. We compared the efficacy and safety of these drugs for this indication. METHODS In this parallel, open-label, randomised controlled trial, patients were aged at least 18 years, had an acute severe flare of ulcerative colitis defined by a Lichtiger score greater than 10 points, and had been given an unsuccessful course of high-dose intravenous steroids. None of the patients had previously received ciclosporin or infliximab. Between June 1, 2007, and Aug 31, 2010, patients at 27 European centres were randomly assigned (via computer-derived permutation tables; 1:1) to receive either intravenous ciclosporin (2 mg/kg per day for 1 week, followed by oral drug until day 98) or infliximab (5 mg/kg on days 0, 14, and 42). In both groups, azathioprine was started at day 7 in patients with a clinical response. Neither patients nor investigators were masked to study treatment. The primary efficacy outcome was treatment failure defined by absence of a clinical response at day 7, a relapse between day 7 and day 98, absence of steroid-free remission at day 98, a severe adverse event leading to treatment interruption, colectomy, or death. Analysis was by intention to treat. This trial is registered with EudraCT (2006-005299-42) and ClinicalTrials.gov (NCT00542152). FINDINGS 115 patients were randomly assigned; 58 patients were allocated to receive ciclosporin and 57 to receive infliximab. Treatment failure occurred in 35 (60%) patients given ciclosporin and 31 (54%) given infliximab (absolute risk difference 6%; 95% CI -7 to 19; p=0·52). Nine (16%) patients in the ciclosporin group and 14 (25%) in the infliximab group had severe adverse events. INTERPRETATION Ciclosporin was not more effective than infliximab in patients with acute severe ulcerative colitis refractory to intravenous steroids. In clinical practice, treatment choice should be guided by physician and centre experience. FUNDING Association François Aupetit, Société Nationale Française de Gastroentérologie, and the International Organization for the study of Inflammatory Bowel Disease.

Multicenter randomized-control led clinical trial of probiotics (Lactobacillus johnsonii, LA1) on early endoscopic recurrence of Crohn's disease after ileo-caecal resection

Background Seventy percent of Crohns disease (CD) patients exhibit anastomotic recurrence within 1 year after ileo‐caecal surgery. Recent clinical trials suggest the beneficial use of probiotics in the control of intestinal inflammation in pouchitis and ulcerative colitis. This study is a multicenter clinical trial evaluating the efficacy of an oral administration of the probiotic LA1 on early postoperative endoscopic recurrence of CD. Methods Seventy patients with CD were enrolled prior to elective ileo‐caecal resection and randomly assigned after surgery to daily treatment with either Lactobacillus johnsonii, LA1, Nestlé (1010 colony‐forming units, CFU) (group A, n = 34) or placebo (group B, n = 36) for 12 weeks. The primary objective was to assess the effect of LA1 on the endoscopic recurrence rate at 12 weeks. Stratification was performed according to smoking status at randomization. Results Seven and 14 patients were excluded in the LA1 and placebo groups, respectively. In intention‐to‐treat analysis, the mean endoscopic score was not significantly different between the two treatment groups at 3 months (LA1 versus placebo: 1.50 ± 1.32 versus 1.22 ± 1.37, treatment effect: P = 0.48, smoke effect: P = 0.72). The percentage of patients with severe recurrence (i3 + i4) was 21% and 15% in the LA1 and placebo groups, respectively (P = 0.33). Using a per‐protocol (PP) analysis, the mean endoscopic score was not significantly different between the two treatment groups (LA1 versus placebo groups: 1.44 ± 1.31 versus 1.05 ± 1.21, P = 0.32). The percentage of patients with severe recurrence (i3 + i4) was 19% and 9% in the LA1 and placebo groups, respectively (P = 0.054). Clinical relapse rate (CDAI [CD activity index] > 150, with an increase of CDAI > 70 points or greater from baseline) in the LA1 and placebo groups was 15% (4/27) and 13.5% (3/22), respectively (PP analysis: chi‐square test, P = 0.91 and log‐rank test: P = 0.79). Conclusion Oral administration of the probiotic LA1 in patients with CD failed to prevent early endoscopic recurrence at 12 weeks after ileo‐caecal resection. (Inflamm Bowel Dis 2007)