Defining predictors of responsiveness to advanced therapies in Crohn's disease and ulcerative colitis: protocol for the IBD-RESPONSE and nested CD-metaRESPONSE prospective, multicentre, observational cohort study in precision medicine

INTRODUCTION

Characterised by chronic inflammation of the gastrointestinal tract, inflammatory bowel disease (IBD) symptoms including diarrhoea, abdominal pain and fatigue can significantly impact patient's quality of life. Therapeutic developments in the last 20 years have revolutionised treatment. However, clinical trials and real-world data show primary non-response rates up to 40%. A significant challenge is an inability to predict which treatment will benefit individual patients.Current understanding of IBD pathogenesis implicates complex interactions between host genetics and the gut microbiome. Most cohorts studying the gut microbiota to date have been underpowered, examined single treatments and produced heterogeneous results. Lack of cross-treatment comparisons and well-powered independent replication cohorts hampers the ability to infer real-world utility of predictive signatures.IBD-RESPONSE will use multi-omic data to create a predictive tool for treatment response. Future patient benefit may include development of biomarker-based treatment stratification or manipulation of intestinal microbial targets. IBD-RESPONSE and downstream studies have the potential to improve quality of life, reduce patient risk and reduce expenditure on ineffective treatments.

METHODS AND ANALYSIS

This prospective, multicentre, observational study will identify and validate a predictive model for response to advanced IBD therapies, incorporating gut microbiome, metabolome, single-cell transcriptome, human genome, dietary and clinical data. 1325 participants commencing advanced therapies will be recruited from ~40 UK sites. Data will be collected at baseline, week 14 and week 54. The primary outcome is week 14 clinical response. Secondary outcomes include clinical remission, loss of response in week 14 responders, corticosteroid-free response/remission, time to treatment escalation and change in patient-reported outcome measures.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Wales Research Ethics Committee 5 (ref: 21/WA/0228). Recruitment is ongoing. Following study completion, results will be submitted for publication in peer-reviewed journals and presented at scientific meetings. Publications will be summarised at www.ibd-response.co.uk.

TRIAL REGISTRATION NUMBER

ISRCTN96296121.

Conserved γδ T cell selection by BTNL proteins limits progression of human inflammatory bowel disease

Murine intraepithelial γδ T cells include distinct tissue-protective cells selected by epithelial butyrophilin-like (BTNL) heteromers. To determine whether this biology is conserved in humans, we characterized the colonic γδ T cell compartment, identifying a diverse repertoire that includes a phenotypically distinct subset coexpressing T cell receptor Vγ4 and the epithelium-binding integrin CD103. This subset was disproportionately diminished and dysregulated in inflammatory bowel disease, whereas on-treatment CD103+γδ T cell restoration was associated with sustained inflammatory bowel disease remission. Moreover, CD103+Vγ4+cell dysregulation and loss were also displayed by humans with germline BTNL3/BTNL8 hypomorphism, which we identified as a risk factor for penetrating Crohn's disease (CD). Thus, BTNL-dependent selection and/or maintenance of distinct tissue-intrinsic γδ T cells appears to be an evolutionarily conserved axis limiting the progression of a complex, multifactorial, tissue-damaging disease of increasing global incidence.

Dose escalation randomised study of efmarodocokin alfa in healthy volunteers and patients with ulcerative colitis

BACKGROUND

The interleukin-22 cytokine (IL-22) has demonstrated efficacy in preclinical colitis models with non-immunosuppressive mechanism of action. Efmarodocokin alfa (UTTR1147A) is a fusion protein agonist that links IL-22 to the crystallisable fragment (Fc) of human IgG4 for improved pharmacokinetic characteristics, but with a mutation to minimise Fc effector functions.

METHODS

This randomised, phase 1b study evaluated the safety, tolerability, pharmacokinetics and pharmacodynamics of repeat intravenous dosing of efmarodocokin alfa in healthy volunteers (HVs; n=32) and patients with ulcerative colitis (n=24) at 30-90 µg/kg doses given once every 2 weeks or monthly (every 4 weeks) for 12 weeks (6:2 active:placebo per cohort).

RESULTS

The most common adverse events (AEs) were on-target, reversible, dermatological effects (dry skin, erythema and pruritus). Dose-limiting non-serious dermatological AEs (severe dry skin, erythema, exfoliation and discomfort) were seen at 90 μg/kg once every 2 weeks (HVs, n=2; patients, n=1). Pharmacokinetics were generally dose-proportional across the dose levels, but patients demonstrated lower drug exposures relative to HVs at the same dose. IL-22 serum biomarkers and IL-22-responsive genes in colon biopsies were induced with active treatment, and microbiota composition changed consistent with a reversal in baseline dysbiosis. As a phase 1b study, efficacy endpoints were exploratory only. Clinical response was observed in 7/18 active-treated and 1/6 placebo-treated patients; clinical remission was observed in 5/18 active-treated and 0/6 placebo-treated patients.

CONCLUSION

Efmarodocokin alfa had an adequate safety and pharmacokinetic profile in HVs and patients. Biomarker data confirmed IL-22R pathway activation in the colonic epithelium. Results support further investigation of this non-immunosuppressive potential inflammatory bowel disease therapeutic.

TRIAL REGISTRATION NUMBER

NCT02749630.

Regulation and Role of αE Integrin and Gut Homing Integrins in Migration and Retention of Intestinal Lymphocytes during Inflammatory Bowel Disease

Adhesion molecules are upregulated in inflamed intestinal mucosa in IBD patients.

Baseline β7 expression does not impact αE induction or gene expression in T cells.

Phospho-SMAD3 is increased in inflamed mucosa in IBD.

Targeting interactions between α4β7 integrin and endothelial adhesion molecule MAdCAM-1 to inhibit lymphocyte migration to the gastrointestinal tract is an effective therapy in inflammatory bowel disease (IBD). Following lymphocyte entry into the mucosa, a subset of these cells expresses αEβ7 integrin, which is expressed on proinflammatory lymphocytes, to increase cell retention. The factors governing lymphocyte migration into the intestinal mucosa and αE integrin expression in healthy subjects and IBD patients remain incompletely understood. We evaluated changes in factors involved in lymphocyte migration and differentiation within tissues. Both ileal and colonic tissue from active IBD patients showed upregulation of ICAM-1, VCAM-1, and MAdCAM-1 at the gene and protein levels compared with healthy subjects and/or inactive IBD patients. β1 and β7 integrin expression on circulating lymphocytes was similar across groups. TGF-β1 treatment induced expression of αE on both β7⁺ and β7⁻ T cells, suggesting that cells entering the mucosa independently of MAdCAM-1/α4β7 can become αEβ7⁺. ITGAE gene polymorphisms did not alter protein induction following TGF-β1 stimulation. Increased phospho-SMAD3, which is directly downstream of TGF-β, and increased TGF-β–responsive gene expression were observed in the colonic mucosa of IBD patients. Finally, in vitro stimulation experiments showed that baseline β7 expression had little effect on cytokine, chemokine, transcription factor, and effector molecule gene expression in αE⁺ and αE⁻ T cells. These findings suggest cell migration to the gut mucosa may be altered in IBD and α4β7⁻, and α4β7⁺ T cells may upregulate αEβ7 in response to TGF-β once within the gut mucosa.

Oral Ferric Maltol Does Not Adversely Affect the Intestinal Microbiome of Patients or Mice, But Ferrous Sulphate Does

BACKGROUND AND AIMS

Altering dietary ferrous sulphate (FS) consumption exacerbates a murine model of colitis and alters the intestinal microbiome. We investigated the impact of oral ferric maltol (FM) and FS on mice with dextran sodium sulphate (DSS) induced colitis, and the microbiome of patients with iron deficiency.

METHODS

Mice had acute colitis induced, with 2% DSS for 5 days, followed by water. During this period, groups of mice were fed standard chow (200 ppm iron, SC, n = 8), or SC with 200ppm FS supplementation (n = 16, FSS), or SC with 200 ppm FM supplementation (n = 16, FMS). Clinical, pathological and microbiome assessments were compared at days 1 and 10. Fecal bacterial gDNA was extracted and the microbiome assessed by sequencing. Statistical inferences were made using MacQIIME. Principal Coordinates Analysis were used to visualize beta-diversity cluster analysis. Ten patients with IDA were treated with FS, and six with inactive inflammatory bowel disease received FM, supplements for four weeks: pre- and mid-treatment fecal samples were collected: the microbiome was assessed (see above).

RESULTS

In mice, after DSS treatment, there was a decrease in many genera in the SC and FSS groups: Lactobacillales increased in mice that received FMS. In humans, FS treatment led to an increase in five genera, but FM was not associated with any measurable change. The severity of DSS-induced colitis was greater with FSS than FMS.

CONCLUSIONS

This study demonstrates differential and unique influences of ferric maltol and ferrous sulphate supplements on intestinal microbiota. These differences might contribute to the different side effects associated with these preparations.

The Impact of NOD2 Genetic Variants on the Gut Mycobiota in Crohn's Disease Patients in Remission and in Individuals Without Gastrointestinal Inflammation

BACKGROUND AND AIMS

Historical and emerging data implicate fungi in Crohn's disease [CD] pathogenesis. However, a causal link between mycobiota, dysregulated immunity, and any impact of NOD2 variants remains elusive. This study aims to evaluate associations between NOD2 variants and faecal mycobiota in CD patients and non-CD subjects.

METHODS

Faecal samples were obtained from 34 CD patients [18 NOD2 mutant, 16 NOD2 wild-type] identified from the UK IBD Genetics Consortium. To avoid confounding influence of mucosal inflammation, CD patients were in clinical remission and had a faecal calprotectin <250 μg/g; 47 non-CD subjects were included as comparator groups, including 22 matched household [four NOD2 mutant] and 25 non-household subjects with known NOD2 genotype [14 NOD2 mutant] identified by the NIHR BioResource Cambridge. Faecal mycobiota composition was determined using internal transcribed spacer 1 [ITS1] sequencing and was compared with 16S rRNA gene sequences and volatile organic compounds.

RESULTS

CD was associated with higher numbers of fungal observed taxonomic units [OTUs] [p = 0.033]. Principal coordinates analysis using Jaccard index [p = 0.018] and weighted Bray-Curtis dissimilarities [p = 0.01] showed Candida spp. clustered closer to CD patients whereas Cryptococcus spp. clustered closer to non-CD. In CD, we found higher relative abundance of Ascomycota [p = 0.001] and lower relative abundance Basidiomycota [p = 0.019] phyla. An inverse relationship was found between bacterial and fungal Shannon diversity in NOD2 wild-type which was independent of CD [r = -0.349; p = 0.029].

CONCLUSIONS

This study confirms compositional changes in the gut mycobiota in CD and provides evidence that fungi may play a role in CD pathogenesis. No NOD2 genotype-specific differences were observed in the faecal mycobiota.

Micro-mechanical damage of needle puncture on bovine annulus fibrosus fibrils studied using polarization-resolved Second Harmonic Generation(P-SHG) microscopy

Needle injection has been widely used in spinal therapeutic or diagnostic processes, such as discography. The use of needles has been suspected in causing mild disc degeneration which can lead to long-term back pain. However, the localised microscopic damage caused by needles has not been well studied. The local progressive damage on a microscopic level caused by needle punctures on the surface of bovine annulus fibrosus was investigated. Four different sizes of needle were used for the puncture and twenty-nine bovine intervertebral discs were studied. Polarization-resolved second harmonic generation and fluorescent microscopy were used to study the local microscopic structural changes in collagen and cell nuclei due to needle damage. Repeated 70 cyclic loadings at ±5% of axial strain were applied after the needle puncture in order to assess progressive damage caused by the needle. Puncture damage on annulus fibrosus were observed either collagen fibre bundles being pushed aside, being cut through or combination of both with part being lift or pushed in. The progressive damage was found less relevant to the needle size and more progressive damage was only observed using the larger needle. Two distinct populations of collagen, in which one was relatively more organised than the other population, were observed especially after the puncture from skewed distribution of polarization-SHG analysis. Cell shape was found rounder near the puncture site where collagen fibres were damaged.

HLA-DQA1*05 Carriage Associated With Development of Anti-Drug Antibodies to Infliximab and Adalimumab in Patients With Crohn's Disease

BACKGROUND & AIMS

Anti-tumor necrosis factor (anti-TNF) therapies are the most widely used biologic drugs for treating immune-mediated diseases, but repeated administration can induce the formation of anti-drug antibodies. The ability to identify patients at increased risk for development of anti-drug antibodies would facilitate selection of therapy and use of preventative strategies.

METHODS

We performed a genome-wide association study to identify variants associated with time to development of anti-drug antibodies in a discovery cohort of 1240 biologic-naïve patients with Crohn's disease starting infliximab or adalimumab therapy. Immunogenicity was defined as an anti-drug antibody titer ≥10 AU/mL using a drug-tolerant enzyme-linked immunosorbent assay. Significant association signals were confirmed in a replication cohort of 178 patients with inflammatory bowel disease.

RESULTS

The HLA-DQA1*05 allele, carried by approximately 40% of Europeans, significantly increased the rate of immunogenicity (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.60-2.25; P = 5.88 × 10-13). The highest rates of immunogenicity, 92% at 1 year, were observed in patients treated with infliximab monotherapy who carried HLA-DQA1*05; conversely the lowest rates of immunogenicity, 10% at 1 year, were observed in patients treated with adalimumab combination therapy who did not carry HLA-DQA1*05. We confirmed this finding in the replication cohort (HR, 2.00; 95% CI, 1.35-2.98; P = 6.60 × 10-4). This association was consistent for patients treated with adalimumab (HR, 1.89; 95% CI, 1.32-2.70) or infliximab (HR, 1.92; 95% CI, 1.57-2.33), and for patients treated with anti-TNF therapy alone (HR, 1.75; 95% CI, 1.37-2.22) or in combination with an immunomodulator (HR, 2.01; 95% CI, 1.57-2.58).

CONCLUSIONS

In an observational study, we found a genome-wide significant association between HLA-DQA1*05 and the development of antibodies against anti-TNF agents. A randomized controlled biomarker trial is required to determine whether pretreatment testing for HLA-DQA1*05 improves patient outcomes by helping physicians select anti-TNF and combination therapies. ClinicalTrials.gov ID: NCT03088449.

Predictors of anti-TNF treatment failure in anti-TNF-naive patients with active luminal Crohn's disease: a prospective, multicentre, cohort study

BACKGROUND

Anti-TNF drugs are effective treatments for the management of Crohn's disease but treatment failure is common. We aimed to identify clinical and pharmacokinetic factors that predict primary non-response at week 14 after starting treatment, non-remission at week 54, and adverse events leading to drug withdrawal.

METHODS

The personalised anti-TNF therapy in Crohn's disease study (PANTS) is a prospective observational UK-wide study. We enrolled anti-TNF-naive patients (aged ≥6 years) with active luminal Crohn's disease at the time of first exposure to infliximab or adalimumab between March 7, 2013, and July 15, 2016. Patients were evaluated for 12 months or until drug withdrawal. Demographic data, smoking status, age at diagnosis, disease duration, location, and behaviour, previous medical and drug history, and previous Crohn's disease-related surgeries were recorded at baseline. At every visit, disease activity score, weight, therapy, and adverse events were recorded; drug and total anti-drug antibody concentrations were also measured. Treatment failure endpoints were primary non-response at week 14, non-remission at week 54, and adverse events leading to drug withdrawal. We used regression analyses to identify which factors were associated with treatment failure.

FINDINGS

We enrolled 955 patients treated with infliximab (753 with originator; 202 with biosimilar) and 655 treated with adalimumab. Primary non-response occurred in 295 (23·8%, 95% CI 21·4-26·2) of 1241 patients who were assessable at week 14. Non-remission at week 54 occurred in 764 (63·1%, 60·3-65·8) of 1211 patients who were assessable, and adverse events curtailed treatment in 126 (7·8%, 6·6-9·2) of 1610 patients. In multivariable analysis, the only factor independently associated with primary non-response was low drug concentration at week 14 (infliximab: odds ratio 0·35 [95% CI 0·20-0·62], p=0·00038; adalimumab: 0·13 [0·06-0·28], p<0·0001); the optimal week 14 drug concentrations associated with remission at both week 14 and week 54 were 7 mg/L for infliximab and 12 mg/L for adalimumab. Continuing standard dosing regimens after primary non-response was rarely helpful; only 14 (12·4% [95% CI 6·9-19·9]) of 113 patients entered remission by week 54. Similarly, week 14 drug concentration was also independently associated with non-remission at week 54 (0·29 [0·16-0·52] for infliximab; 0·03 [0·01-0·12] for adalimumab; p<0·0001 for both). The proportion of patients who developed anti-drug antibodies (immunogenicity) was 62·8% (95% CI 59·0-66·3) for infliximab and 28·5% (24·0-32·7) for adalimumab. For both drugs, suboptimal week 14 drug concentrations predicted immunogenicity, and the development of anti-drug antibodies predicted subsequent low drug concentrations. Combination immunomodulator (thiopurine or methotrexate) therapy mitigated the risk of developing anti-drug antibodies (hazard ratio 0·39 [95% CI 0·32-0·46] for infliximab; 0·44 [0·31-0·64] for adalimumab; p<0·0001 for both). For infliximab, multivariable analysis of immunododulator use, and week 14 drug and anti-drug antibody concentrations showed an independent effect of immunomodulator use on week 54 non-remission (odds ratio 0·56 [95% CI 0·38-0·83], p=0·004).

INTERPRETATION

Anti-TNF treatment failure is common and is predicted by low drug concentrations, mediated in part by immunogenicity. Clinical trials are required to investigate whether personalised induction regimens and treatment-to-target dose intensification improve outcomes.

FUNDING

Guts UK, Crohn's and Colitis UK, Cure Crohn's Colitis, AbbVie, Merck Sharp and Dohme, Napp Pharmaceuticals, Pfizer, and Celltrion.

Association of Genetic Variants in NUDT15 With Thiopurine-Induced Myelosuppression in Patients With Inflammatory Bowel Disease

IMPORTANCE

Use of thiopurines may be limited by myelosuppression. TPMT pharmacogenetic testing identifies only 25% of at-risk patients of European ancestry. Among patients of East Asian ancestry, NUDT15 variants are associated with thiopurine-induced myelosuppression (TIM).

OBJECTIVE

To identify genetic variants associated with TIM among patients of European ancestry with inflammatory bowel disease (IBD).

DESIGN, SETTING, AND PARTICIPANTS

Case-control study of 491 patients affected by TIM and 679 thiopurine-tolerant unaffected patients who were recruited from 89 international sites between March 2012 and November 2015. Genome-wide association studies (GWAS) and exome-wide association studies (EWAS) were conducted in patients of European ancestry. The replication cohort comprised 73 patients affected by TIM and 840 thiopurine-tolerant unaffected patients.

EXPOSURES

Genetic variants associated with TIM.

MAIN OUTCOMES AND MEASURES

Thiopurine-induced myelosuppression, defined as a decline in absolute white blood cell count to 2.5 × 109/L or less or a decline in absolute neutrophil cell count to 1.0 × 109/L or less leading to a dose reduction or drug withdrawal.

RESULTS

Among 1077 patients (398 affected and 679 unaffected; median age at IBD diagnosis, 31.0 years [interquartile range, 21.2 to 44.1 years]; 540 [50%] women; 602 [56%] diagnosed as having Crohn disease), 919 (311 affected and 608 unaffected) were included in the GWAS analysis and 961 (328 affected and 633 unaffected) in the EWAS analysis. The GWAS analysis confirmed association of TPMT (chromosome 6, rs11969064) with TIM (30.5% [95/311] affected vs 16.4% [100/608] unaffected patients; odds ratio [OR], 2.3 [95% CI, 1.7 to 3.1], P = 5.2 × 10-9). The EWAS analysis demonstrated an association with an in-frame deletion in NUDT15 (chromosome 13, rs746071566) and TIM (5.8% [19/328] affected vs 0.2% [1/633] unaffected patients; OR, 38.2 [95% CI, 5.1 to 286.1], P = 1.3 × 10-8), which was replicated in a different cohort (2.7% [2/73] affected vs 0.2% [2/840] unaffected patients; OR, 11.8 [95% CI, 1.6 to 85.0], P = .03). Carriage of any of 3 coding NUDT15 variants was associated with an increased risk (OR, 27.3 [95% CI, 9.3 to 116.7], P = 1.1 × 10-7) of TIM, independent of TPMT genotype and thiopurine dose.

CONCLUSIONS AND RELEVANCE

Among patients of European ancestry with IBD, variants in NUDT15 were associated with increased risk of TIM. These findings suggest that NUDT15 genotyping may be considered prior to initiation of thiopurine therapy; however, further study including additional validation in independent cohorts is required.

AlphaE Integrin Expression Is Increased in the Ileum Relative to the Colon and Unaffected by Inflammation

BACKGROUND

Recent findings suggest that αE expression is enriched on effector T cells and that intestinal αE+ T cells have increased expression of inflammatory cytokines. αE integrin expression is a potential predictive biomarker for response to etrolizumab, a monoclonal antibody against β7 integrin that targets both α4β7 and αEβ7. We evaluated the prevalence and localization of αE+ cells as well as total αE gene expression in healthy and inflammatory bowel disease patients.

METHODS

αE+ cells were identified in ileal and colonic biopsies by immunohistochemistry and counted using an automated algorithm. Gene expression was assessed by quantitative reverse-transcriptase polymerase chain reaction.

RESULTS

In both healthy and inflammatory bowel disease patients, significantly more αE+ cells were present in the epithelium and lamina propria of ileal compared with colonic biopsies. αE gene expression levels were also significantly higher in ileal compared with colonic biopsies. Paired biopsies from the same patient showed moderate correlation of αE expression between the ileum and colon. Inflammation did not affect αE expression, and neither endoscopy nor histology scores correlated with αE gene expression. αE expression was not different between patients based on concomitant medication use except 5-aminosalicylic acid.

CONCLUSION

αE+ cells, which have been shown to have inflammatory potential, are increased in the ileum in comparison with the colon in both Crohn's disease and ulcerative colitis, as well as in healthy subjects. In inflammatory bowel disease patients, αE levels are stable, regardless of inflammatory status or most concomitant medications, which could support its use as a biomarker for etrolizumab.

Exome Sequencing and Genotyping Identify a Rare Variant in NLRP7 Gene Associated With Ulcerative Colitis

BACKGROUND AND AIMS

Although genome-wide association studies [GWAS] in inflammatory bowel disease [IBD] have identified a large number of common disease susceptibility alleles for both Crohn's disease [CD] and ulcerative colitis [UC], a substantial fraction of IBD heritability remains unexplained, suggesting that rare coding genetic variants may also have a role in pathogenesis. We used high-throughput sequencing in families with multiple cases of IBD, followed by genotyping of cases and controls, to investigate whether rare protein-altering genetic variants are associated with susceptibility to IBD.

METHODS

Whole-exome sequencing was carried out in 10 families in whom three or more individuals were affected with IBD. A stepwise filtering approach was applied to exome variants, to identify potential causal variants. Follow-up genotyping was performed in 6025 IBD cases [2948 CD; 3077 UC] and 7238 controls.

RESULTS

Our exome variant analysis revealed coding variants in the NLRP7 gene that were present in affected individuals in two distinct families. Genotyping of the two variants, p.S361L and p.R801H, in IBD cases and controls showed that the p.S361L variant was significantly associated with an increased risk of ulcerative colitis [odds ratio 4.79, p = 0.0039] and IBD [odds ratio 3.17, p = 0.037]. A combined analysis of both variants showed suggestive association with an increased risk of IBD [odds ratio 2.77, p = 0.018].

CONCLUSIONS

The results suggest that NLRP7 signalling and inflammasome formation may be a significant component in the pathogenesis of IBD.

Can faecal calprotectin predict relapse in inflammatory bowel disease: a mini review

Crohn's disease and ulcerative colitis are chronic inflammatory disorders affecting the gastrointestinal tract. Faecal calprotectin is a protein complex of the S-100 family of calcium-binding proteins present in inflammatory cells that can be measured in stool samples, which act as a biomarker for bowel inflammation. Elevated faecal calprotectin has been shown to reflect the presence of ongoing mucosal inflammation, which improves with mucosal healing. The aim of this review was to evaluate the available evidence on the ability of faecal calprotectin to predict a relapse in inflammatory bowel disease. Multiple retrospective studies have shown that patients who relapse have significantly higher levels of calprotectin in their stool compared with non-relapsers, especially in ulcerative colitis. Elevated faecal calprotectin postoperatively in Crohn's disease was also shown to be indicative of a relapse. However, the association of a raised faecal calprotectin and relapse is not universal and may be explained by the different patterns of mucosal inflammatory activity that exist. In conclusion, we put forward our hypothesis that changes such as a rise in faecal calprotectin levels may be more predictive of a relapse than absolute values.

αEβ7 Integrin Identifies Subsets of Pro-Inflammatory Colonic CD4+ T Lymphocytes in Ulcerative Colitis

BACKGROUND AND AIMS

The αEβ7 integrin is crucial for retention of T lymphocytes at mucosal surfaces through its interaction with E-cadherin. Pathogenic or protective functions of these cells during human intestinal inflammation, such as ulcerative colitis [UC], have not previously been defined, with understanding largely derived from animal model data. Defining this phenotype in human samples is important for understanding UC pathogenesis and is of translational importance for therapeutic targeting of αEβ7-E-cadherin interactions.

METHODS

αEβ7+ and αEβ7- colonic T cell localization, inflammatory cytokine production and expression of regulatory T cell-associated markers were evaluated in cohorts of control subjects and patients with active UC by immunohistochemistry, flow cytometry and real-time PCR of FACS-purified cell populations.

RESULTS

CD4+αEβ7+ T lymphocytes from both healthy controls and UC patients had lower expression of regulatory T cell-associated genes, including FOXP3, IL-10, CTLA-4 and ICOS in comparison with CD4+αEβ7- T lymphocytes. In UC, CD4+αEβ7+ lymphocytes expressed higher levels of IFNγ and TNFα in comparison with CD4+αEβ7- lymphocytes. Additionally the CD4+αEβ7+ subset was enriched for Th17 cells and the recently described Th17/Th1 subset co-expressing both IL-17A and IFNγ, both of which were found at higher frequencies in UC compared to control.

CONCLUSION

αEβ7 integrin expression on human colonic CD4+ T cells was associated with increased production of pro-inflammatory Th1, Th17 and Th17/Th1 cytokines, with reduced expression of regulatory T cell-associated markers. These data suggest colonic CD4+αEβ7+ T cells are pro-inflammatory and may play a role in UC pathobiology.

Exploring the genetic architecture of inflammatory bowel disease by whole-genome sequencing identifies association at ADCY7

To further resolve the genetic architecture of the inflammatory bowel diseases ulcerative colitis and Crohn's disease, we sequenced the whole genomes of 4,280 patients at low coverage and compared them to 3,652 previously sequenced population controls across 73.5 million variants. We then imputed from these sequences into new and existing genome-wide association study cohorts and tested for association at ∼12 million variants in a total of 16,432 cases and 18,843 controls. We discovered a 0.6% frequency missense variant in ADCY7 that doubles the risk of ulcerative colitis. Despite good statistical power, we did not identify any other new low-frequency risk variants and found that such variants explained little heritability. We detected a burden of very rare, damaging missense variants in known Crohn's disease risk genes, suggesting that more comprehensive sequencing studies will continue to improve understanding of the biology of complex diseases.

Genome-wide association study implicates immune activation of multiple integrin genes in inflammatory bowel disease

Genetic association studies have identified 215 risk loci for inflammatory bowel disease, thereby uncovering fundamental aspects of its molecular biology. We performed a genome-wide association study of 25,305 individuals and conducted a meta-analysis with published summary statistics, yielding a total sample size of 59,957 subjects. We identified 25 new susceptibility loci, 3 of which contain integrin genes that encode proteins in pathways that have been identified as important therapeutic targets in inflammatory bowel disease. The associated variants are correlated with expression changes in response to immune stimulus at two of these genes (ITGA4 and ITGB8) and at previously implicated loci (ITGAL and ICAM1). In all four cases, the expression-increasing allele also increases disease risk. We also identified likely causal missense variants in a gene implicated in primary immune deficiency, PLCG2, and a negative regulator of inflammation, SLAMF8. Our results demonstrate that new associations at common variants continue to identify genes relevant to therapeutic target identification and prioritization.

Genome-wide association study identifies distinct genetic contributions to prognosis and susceptibility in Crohn's disease

For most immune-mediated diseases, the main determinant of patient well-being is not the diagnosis itself but instead the course that the disease takes over time (prognosis). Prognosis may vary substantially between patients for reasons that are poorly understood. Familial studies support a genetic contribution to prognosis, but little evidence has been found for a proposed association between prognosis and the burden of susceptibility variants. To better characterize how genetic variation influences disease prognosis, we performed a within-cases genome-wide association study in two cohorts of patients with Crohn's disease. We identified four genome-wide significant loci, none of which showed any association with disease susceptibility. Conversely, the aggregated effect of all 170 disease susceptibility loci was not associated with disease prognosis. Together, these data suggest that the genetic contribution to prognosis in Crohn's disease is largely independent of the contribution to disease susceptibility and point to a biology of prognosis that could provide new therapeutic opportunities.

Association Between Response to Etrolizumab and Expression of Integrin αE and Granzyme A in Colon Biopsies of Patients With Ulcerative Colitis

BACKGROUND & AIMS

Etrolizumab is a humanized monoclonal antibody against the β7 integrin subunit that has shown efficacy vs placebo in patients with moderate to severely active ulcerative colitis (UC). Patients with colon tissues that expressed high levels of the integrin αE gene (ITGAE) appeared to have the best response. We compared differences in colonic expression of ITGAE and other genes between patients who achieved clinical remission with etrolizumab vs those who did.

METHODS

We performed a retrospective analysis of data collected from 110 patients with UC who participated in a phase 2 placebo-controlled trial of etrolizumab, as well as from 21 patients with UC or without inflammatory bowel disease (controls) enrolled in an observational study at a separate site. Colon biopsies were collected from patients in both studies and analyzed by immunohistochemistry and gene expression profiling. Mononuclear cells were isolated and analyzed by flow cytometry. We identified biomarkers associated with response to etrolizumab. In the placebo-controlled trial, clinical remission was defined as total Mayo Clinic Score ≤2, with no individual subscore >1, and mucosal healing was defined as endoscopic score ≤1.

RESULTS

Colon tissues collected at baseline from patients who had a clinical response to etrolizumab expressed higher levels of T-cell-associated genes than patients who did not respond (P < .05). Colonic CD4(+) integrin αE(+) cells from patients with UC expressed higher levels of granzyme A messenger RNA (GZMA mRNA) than CD4(+) αE(-) cells (P < .0001); granzyme A and integrin αE protein were detected in the same cells. Of patients receiving 100 mg etrolizumab, a higher proportion of those with high levels of GZMA mRNA (41%) or ITGAE mRNA (38%) than those with low levels of GZMA (6%) or ITGAE mRNA (13%) achieved clinical remission (P < .05) and mucosal healing (41% GZMA(high) vs 19% GZMA(low) and 44% ITGAE(high) vs 19% ITGAE(low)). Compared with ITGAE(low) and GZMA(low) patients, patients with ITGAE(high) and GZMA(high) had higher baseline numbers of epithelial crypt-associated integrin αE(+) cells (P < .01 for both), but a smaller number of crypt-associated integrin αE(+) cells after etrolizumab treatment (P < .05 for both). After 10 weeks of etrolizumab treatment, expression of genes associated with T-cell activation and genes encoding inflammatory cytokines decreased by 40%-80% from baseline (P < .05) in patients with colon tissues expressing high levels of GZMA at baseline.

CONCLUSIONS

Levels of GZMA and ITGAE mRNAs in colon tissues can identify patients with UC who are most likely to benefit from etrolizumab; expression levels decrease with etrolizumab administration in biomarker(high) patients. Larger, prospective studies of markers are needed to assess their clinical value.

The micromechanics of the superficial zone of articular cartilage

OBJECTIVE

To investigate the relationships between the unique mechanical and structural properties of the superficial zone of articular cartilage on the microscopic scale.

DESIGN

Fresh unstained equine metacarpophalangeal cartilage samples were mounted on tensile and compressive loading rigs on the stage of a multiphoton microscope. Sequential image stacks were acquired under incremental loads together with simultaneous measurements of the applied stress and strain. Second harmonic generation was used to visualise the collagen fibre network, while two photon fluorescence was used to visualise elastin fibres and cells. The changes visualised by each modality were tracked between successive loads.

RESULTS

The deformation of the cartilage matrix was heterogeneous on the microscopic length scale. This was evident from local strain maps, which showed shearing between different regions of collagen under tensile strain, corrugations in the articular surface at higher tensile strains and a non-uniform distribution of compressive strain in the axial direction. Chondrocytes elongated and rotated under tensile strain and were compressed in the axial direction under compressive load. The magnitude of deformation varied between cells, indicating differences in either load transmission through the matrix or the mechanical properties of individual cells. Under tensile loading the reorganisation of the elastin network differed from a homogeneous elastic response, indicating that it forms a functional structure.

CONCLUSIONS

This study highlights the complexity of superficial zone mechanics and demonstrates that the response of the collagen matrix, elastin fibres and chondrocytes are all heterogeneous on the microscopic scale.

Etrolizumab as induction therapy for ulcerative colitis: a randomised, controlled, phase 2 trial

BACKGROUND

Etrolizumab is a humanised monoclonal antibody that selectively binds the β7 subunit of the heterodimeric integrins α4β7 and αEβ7. We aimed to assess etrolizumab in patients with moderately-to-severely active ulcerative colitis.

METHODS

In this double-blind, placebo-controlled, randomised, phase 2 study, patients with moderately-to-severely active ulcerative colitis who had not responded to conventional therapy were recruited from 40 referral centres in 11 countries. Eligible patients (aged 18-75 years; Mayo Clinic Score [MCS] of 5 of higher [or ≥6 in USA]; and disease extending 25 cm or more from anal verge) were randomised (1:1:1) to one of two dose levels of subcutaneous etrolizumab (100 mg at weeks 0, 4, and 8, with placebo at week 2; or 420 mg loading dose [LD] at week 0 followed by 300 mg at weeks 2, 4, and 8), or matching placebo. The primary endpoint was clinical remission at week 10, defined as MCS of 2 or less (with no individual subscore of >1), analysed in the modified intention-to-treat population (mITT; all randomly assigned patients who had received at least one dose of study drug, had at least one post-baseline disease-activity assessment, and had a centrally read screening endoscopic subscore of ≥2). This study is registered with ClinicalTrials.gov, number NCT01336465.

FINDINGS

Between Sept 2, 2011, and July 11, 2012, 124 patients were randomly assigned, of whom five had a endoscopic subscore of 0 or 1 and were excluded from the mITT population, leaving 39 patients in the etrolizumab 100 mg group, 39 in the etrolizumab 300 mg plus LD group, and 41 in the placebo group for the primary analyses. No patients in the placebo group had clinical remission at week 10, compared with eight (21% [95% CI 7-36]) patients in the etrolizumab 100 mg group (p=0·0040) and four (10% [0·2-24]) patients in the 300 mg plus LD group (p=0·048). Adverse events occurred in 25 (61%) of 41 patients in the etrolizumab 100 mg group (five [12%] of which were regarded as serious), 19 (48%) of 40 patients in the etrolizumab 300 mg plus LD group (two [5%] serious), and 31 (72%) of 43 patients in the placebo group (five [12%] serious).

INTERPRETATION

Etrolizumab was more likely to lead to clinical remission at week 10 than was placebo. Therefore, blockade of both α4β7 and αEβ7 might provide a unique therapeutic approach for the treatment of ulcerative colitis, and phase 3 studies have been planned.

FUNDING

Genentech.

Micromechanical response of articular cartilage to tensile load measured using nonlinear microscopy

Articular cartilage (AC) is a highly anisotropic biomaterial, and its complex mechanical properties have been a topic of intense investigation for over 60 years. Recent advances in the field of nonlinear optics allow the individual constituents of AC to be imaged in living tissue without the need for exogenous contrast agents. Combining mechanical testing with nonlinear microscopy provides a wealth of information about microscopic responses to load. This work investigates the inhomogeneous distribution of strain in loaded AC by tracking the movement and morphological changes of individual chondrocytes using point pattern matching and Bayesian modeling. This information can be used to inform models of mechanotransduction and pathogenesis, and is readily extendable to various other connective tissues.

Drug advances in inflammatory bowel disease

The pathogenesis of inflammatory bowel disease (IBD) remains incompletely understood, but is thought to be a consequence of immune dysregulation, impaired mucosal integrity, enteric bacterial dysbiosis and genetic susceptibility factors. Recent drug advances in the treatment of IBD have clarified the role of existing medication, including 5-amino-salicylic acids (5-ASAs) and has seen a burgeoning use of treatment with biologicals. With recent advances in our understanding of these debilitating diseases, it is hoped that novel therapeutic targets can be identified.

A randomised phase I study of etrolizumab (rhuMAb β7) in moderate to severe ulcerative colitis

OBJECTIVE

Etrolizumab (rhuMAb β7, anti-β7, PRO145223) is a humanised monoclonal antibody targeting the β7 subunit of the heterodimeric integrins α4β7 and αEβ7, which are implicated in leucocyte migration and retention in ulcerative colitis (UC). This randomised phase I study evaluated the safety and pharmacology of etrolizumab in patients with moderate to severe UC.

DESIGN

In the single ascending dose (SAD) stage, etrolizumab (0.3, 1.0, 3.0, 10 mg/kg intravenous, 3.0 mg/kg subcutaneous (SC) or placebo) was administered 4:1 (n=25) in each cohort. In the multiple dose (MD) stage, new patients received monthly etrolizumab (0.5 mg/kg SC (n=4), 1.5 mg/kg SC (n=5), 3.0 mg/kg SC (n=4), 4.0 mg/kg intravenous (n=5)) or placebo (n=5). The pharmacokinetics was studied and Mayo Clinic Score evaluated at baseline, day 29 (SAD), and days 43 and 71 (MD).

RESULTS

In the SAD stage, there were no dose limiting toxicities, infusion or injection site reactions. Two impaired wound healing serious adverse events occurred in two patients receiving etrolizumab. In the MD stage, there were no dose limiting toxicities, and no infusion or injection site reactions. Headache was the most common adverse event, occurring more often in etrolizumab patients. Antietrolizumab antibodies were detected in two subjects. The duration of β7 receptor full occupancy was dose related. A clinical response was observed in 12/18 patients, and clinical remission in 3/18 patients treated with etrolizumab in the MD stage, compared with 4/5 and 1/5 placebo patients, respectively.

CONCLUSION

Etrolizumab is well tolerated in moderate to severe UC. Further investigation is warranted.

Sexually transmitted infections manifesting as proctitis

There is a rising incidence of several sexually transmitted infections (STIs), many of which can present with proctitis. Causative organisms include Neisseria gonorrhoeae, Chlamydia trachomatis, herpes simplex virus, Treponema pallidum (syphilis), Giardia lamblia (giardiasis) and Entamoeba histolytica (amoebiasis). This paper outlines important clinical discriminators and key investigations to distinguish these organisms from non-infective pathology that include inflammatory bowel disease, solitary rectal ulcer syndrome and Behçet's syndrome. Management of these infections is described and suggestions are made for successful gastroenterology clinical consultation when an STI is suspected.

Meta-analysis identifies 29 additional ulcerative colitis risk loci, increasing the number of confirmed associations to 47

Genome-wide association studies and candidate gene studies in ulcerative colitis have identified 18 susceptibility loci. We conducted a meta-analysis of six ulcerative colitis genome-wide association study datasets, comprising 6,687 cases and 19,718 controls, and followed up the top association signals in 9,628 cases and 12,917 controls. We identified 29 additional risk loci (P < 5 × 10(-8)), increasing the number of ulcerative colitis-associated loci to 47. After annotating associated regions using GRAIL, expression quantitative trait loci data and correlations with non-synonymous SNPs, we identified many candidate genes that provide potentially important insights into disease pathogenesis, including IL1R2, IL8RA-IL8RB, IL7R, IL12B, DAP, PRDM1, JAK2, IRF5, GNA12 and LSP1. The total number of confirmed inflammatory bowel disease risk loci is now 99, including a minimum of 28 shared association signals between Crohn's disease and ulcerative colitis.

Meta-analysis identifies 29 additional ulcerative colitis risk loci, increasing the number of confirmed associations to 47

Genome-wide association studies and candidate gene studies in ulcerative colitis have identified 18 susceptibility loci. We conducted a meta-analysis of six ulcerative colitis genome-wide association study datasets, comprising 6,687 cases and 19,718 controls, and followed up the top association signals in 9,628 cases and 12,917 controls. We identified 29 additional risk loci (P < 5 × 10(-8)), increasing the number of ulcerative colitis-associated loci to 47. After annotating associated regions using GRAIL, expression quantitative trait loci data and correlations with non-synonymous SNPs, we identified many candidate genes that provide potentially important insights into disease pathogenesis, including IL1R2, IL8RA-IL8RB, IL7R, IL12B, DAP, PRDM1, JAK2, IRF5, GNA12 and LSP1. The total number of confirmed inflammatory bowel disease risk loci is now 99, including a minimum of 28 shared association signals between Crohn's disease and ulcerative colitis.

Measurement of faecal calprotectin and lactoferrin in inflammatory bowel disease

Crohn's disease and ulcerative colitis are chronic relapsing gastrointestinal conditions characterised by an influx of inflammatory cells to the affected gut mucosa. The mainstay of diagnosing and re-evaluating these conditions in clinical practice and research is by invasive serological, radiological, endoscopic and histological assessment. In clinical trials, disease activity is often evaluated using a combination of the above tests plus clinical indices such as the Crohn's Disease Activity Index and Ulcerative Colitis Activity Index. These tools rely on subjective assessment of symptoms and so, often, do not correlate with mucosal inflammation or mucosal healing, which may be the preferred therapeutic end point for long-term inflammatory bowel disease (IBD) management. The faecal biomarkers calprotectin and lactoferrin are neutrophil derived proteins that are stable in faeces and can be detected by quantitative ELISA in small stool samples. Concentrations of both are raised in patients with gastrointestinal mucosal inflammation. They provide a unique, inexpensive, non-invasive method of testing for active inflammatory disease. They can be used to screen for IBD and as a surrogate marker of mucosal healing they are useful in monitoring the response to therapeutic intervention or surgery. They may also predict the clinical course of the disease. This clinical review aims to discuss the current evidence, limitations and potential future uses of these biomarkers in IBD.

Measurement methods and accuracy in copy number variation: failure to replicate associations of beta-defensin copy number with Crohn's disease

The copy number variation in beta-defensin genes on human chromosome 8 has been proposed to underlie susceptibility to inflammatory disorders, but presents considerable challenges for accurate typing on the scale required for adequately powered case-control studies. In this work, we have used accurate methods of copy number typing based on the paralogue ratio test (PRT) to assess beta-defensin copy number in more than 1500 UK DNA samples including more than 1000 cases of Crohn's disease. A subset of 625 samples was typed using both PRT-based methods and standard real-time PCR methods, from which direct comparisons highlight potentially serious shortcomings of a real-time PCR assay for typing this variant. Comparing our PRT-based results with two previous studies based only on real-time PCR, we find no evidence to support the reported association of Crohn's disease with either low or high beta-defensin copy number; furthermore, it is noteworthy that there are disagreements between different studies on the observed frequency distribution of copy number states among European controls. We suggest safeguards to be adopted in assessing and reporting the accuracy of copy number measurement, with particular emphasis on integer clustering of results, to avoid reporting of spurious associations in future case-control studies.

Independent and population-specific association of risk variants at the IRGM locus with Crohn's disease

DNA polymorphisms in a region on chromosome 5q33.1 which contains two genes, immunity related GTPase related family, M (IRGM) and zinc finger protein 300 (ZNF300), are associated with Crohn's disease (CD). The deleted allele of a 20 kb copy number variation (CNV) upstream of IRGM was recently shown to be in strong linkage disequilibrium (LD) with the CD-associated single nucleotide polymorphisms and is itself associated with CD (P < 0.01). The deletion was correlated with increased or reduced expression of IRGM in transformed cells in a cell line-dependent manner, and has been proposed as a likely causal variant. We report here that small insertion/deletion polymorphisms in the promoter and 5' untranslated region of IRGM are, together with the CNV, strongly associated with CD (P = 1.37 x 10(-5) to 1.40 x 10(-9)), and that the CNV and the 5'-untranslated region variant -308(GTTT)(5) contribute independently to CD susceptibility (P = 2.6 x 10(-7) and P = 2 x 10(-5), respectively). We also show that the CD risk haplotype is associated with a significant decrease in IRGM expression (P < 10(-12)) in untransformed lymphocytes from CD patients. Further analysis of these variants in a Japanese CD case-control sample and of IRGM expression in HapMap populations revealed that neither the IRGM insertion/deletion polymorphisms nor the CNV was associated with CD or with altered IRGM expression in the Asian population. This suggests that the involvement of the IRGM risk haplotype in the pathogenesis of CD requires gene-gene or gene-environment interactions which are absent in Asian populations, or that none of the variants analysed are causal, and that the true causal variants arose after the European-Asian split.

Anti-tissue transglutaminase antibodies in the follow-up of adult coeliac disease

BACKGROUND

The detection of auto antibodies directed against tissue transglutaminase (anti-tTG antibodies) has a well-established role in the diagnosis of coeliac disease, but the value of these antibodies in long-term follow-up is controversial.

AIMS

To determine if serial anti-tTG antibody measurements could confirm adherence to a gluten-free diet (GFD) and identify patients at risk of disease complications.

METHODS

In a 54-month cohort follow-up study, 182 adult patients were assessed. Data recorded included self-assessment of GFD adherence; anti-tTG antibody concentration and serum ferritin, vitamin B12 and folate. Where available, bone mineral density (BMD) and duodenal histology data were retrieved.

RESULTS

Persistently elevated anti-tTG antibody levels were significantly associated with abnormal duodenal histology (P < 0.001), low ferritin (P < 0.01) and poor adherence to the GFD (P < 0.001). The specificity was >85% while the sensitivity was 39-60%. Anti-tTG antibody concentrations fell rapidly following successful initiation of a GFD, and maintenance of normalization identified those who continued to be adherent to the diet.

CONCLUSIONS

This study supports a strategy of using anti-tTG antibody concentrations to monitor newly diagnosed and established patients with coeliac disease, and to target dietetic intervention to reduce the risk of complication.

Faecal calprotectin or lactoferrin can identify postoperative recurrence in Crohn's disease

BACKGROUND

Identifying Crohn's disease recurrence in symptomatic patients after ileocaecal resection is difficult. The aim of this study was to evaluate faecal concentrations of granulocyte degradation products in this setting.

METHODS

A postoperative cohort of 13 patients was followed prospectively for 1 year with regular faecal calprotectin (FC) and lactoferrin (FL) measurements. A second postoperative cohort (median 24 months after resection) of 104 patients provided a single stool sample. Faecal measurements were compared with symptom diaries, the Harvey Bradshaw Index, endoscopic examination, C-reactive protein and platelet measurement.

RESULTS

In the uncomplicated course, both markers normalized within 2 months. Both FC and FL correlated significantly with Harvey Bradshaw Index (P < 0.001). Twenty-eight patients with severely clinically active disease had high mean(s.e.) levels of FC (661.1(119.1) microg/g) and FL (116.6(32.2) microg/g); and 43 with clinically inactive disease had low levels of FC (70.2(27.1) microg/g) and FL (5.9(2.4) microg/g). In patients with mild to moderately clinically active disease, FC and FL identified individuals with and without recurrent inflammatory disease. Faecal markers were more accurate at predicting clinical disease activity than C-reactive protein, platelet count or endoscopic appearance.

CONCLUSION

FC and FL are non-invasive tests that can help to identify disease recurrence in symptomatic postoperative patients.

Searching for genotype-phenotype structure: using hierarchical log-linear models in Crohn disease

There has been considerable recent success in the detection of gene-disease associations. We consider here the development of tools that facilitate the more detailed characterization of the effect of a genetic variant on disease. We replace the simplistic classification of individuals according to a single binary disease indicator with classification according to a number of subphenotypes. This more accurately reflects the underlying biological complexity of the disease process, but it poses additional analytical difficulties. Notably, the subphenotypes that make up a particular disease are typically highly associated, and it becomes difficult to distinguish which genes might be causing which subphenotypes. Such problems arise in many complex diseases. Here, we concentrate on an application to Crohn disease (CD). We consider this problem as one of model selection based upon log-linear models, fitted in a Bayesian framework via reversible-jump Metropolis-Hastings approach. We evaluate the performance of our suggested approach with a simple simulation study and then apply the method to a real data example in CD, revealing a sparse disease structure. Most notably, the associated NOD2.908G-->R mutation appears to be directly related to more severe disease behaviors, whereas the other two associated NOD2 variants, 1007L-->FS and 702R-->W, are more generally related to disease in the small bowel (ileum and jejenum). The ATG16L1.300T-->A variant appears to be directly associated with only disease of the small bowel.

Genetic determinants of ulcerative colitis include the ECM1 locus and five loci implicated in Crohn's disease

We report results of a nonsynonymous SNP scan for ulcerative colitis and identify a previously unknown susceptibility locus at ECM1. We also show that several risk loci are common to ulcerative colitis and Crohn's disease (IL23R, IL12B, HLA, NKX2-3 and MST1), whereas autophagy genes ATG16L1 and IRGM, along with NOD2 (also known as CARD15), are specific for Crohn's disease. These data provide the first detailed illustration of the genetic relationship between these common inflammatory bowel diseases.

A randomized, double-blind, placebo-controlled trial of lenalidomide in the treatment of moderately severe active Crohn's disease

BACKGROUND

Therapy targeted at tumour necrosis factor-alpha has an established role in Crohn's disease. Lenalidomide, an analogue of thalidomide, is an oral immunomodulatory agent with powerful antitumour necrosis factor-alpha properties. It is licensed for myeloma and myelodysplastic syndrome. Based upon reports of thalidomide efficacy, lenalidomide was evaluated in Crohn's disease.

AIM

To evaluate the efficacy and safety of lenalidomide in subjects with moderately severe active Crohn's disease.

METHODS

In a multicentre, double-blind, placebo-controlled parallel group study 89 subjects were randomized to lenalidomide 25 mg daily, 5 mg daily or placebo. Subjects were treated for 12 weeks. The primary end point was a 70-point reduction in Crohn's Disease Activity Index.

RESULTS

The overall clinical response rate was not significantly different between the three groups: lenalidomide 25 mg 26%, lenalidomide 5 mg 48% and placebo 39%. Lenalidomide was generally well tolerated with only one serious adverse event, a deep vein thrombosis, being attributed to treatment.

CONCLUSION

Lenalidomide, an oral agent with antitumour necrosis factor-alpha properties, was not effective in active Crohn's disease in contrast to reports of benefit from thalidomide. The reasons for this lack of efficacy are speculative, other physiological activities may offset its action on inflammatory cytokines, or its antitumour necrosis factor-alpha action without apoptosis may be insufficient for activity in Crohn's disease.

Sequence variants in the autophagy gene IRGM and multiple other replicating loci contribute to Crohn's disease susceptibility

A genome-wide association scan in individuals with Crohn's disease by the Wellcome Trust Case Control Consortium detected strong association at four novel loci. We tested 37 SNPs from these and other loci for association in an independent case-control sample. We obtained replication for the autophagy-inducing IRGM gene on chromosome 5q33.1 (replication P = 6.6 x 10(-4), combined P = 2.1 x 10(-10)) and for nine other loci, including NKX2-3, PTPN2 and gene deserts on chromosomes 1q and 5p13.

A nonsynonymous SNP in ATG16L1 predisposes to ileal Crohn's disease and is independent of CARD15 and IBD5

BACKGROUND & AIMS

A genome-wide association scan of nonsynonymous DNA polymorphisms identified association of a threonine-to-alanine substitution (T300A) in the autophagy-related 16-like gene ATG16L1 with Crohn's disease. We investigated this association in independent U.K. cohorts of Crohn's disease and ulcerative colitis.

METHODS

The T300A variant (rs2241880) was genotyped in an independent sample of 727 Crohn's disease and 877 ulcerative colitis cases, and in 579 controls. We then performed an extension analysis combining these data with the U.K. data from the initial study to give a total of 1236 U.K. Crohn's disease cases and 1235 controls to estimate disease risk and test for interaction with the CARD15 and IBD5 risk loci and for association with disease subtypes.

RESULTS

The association of T300A was replicated in the independent sample of 727 Crohn's disease cases (P = .001), and was strongly associated in the extended analysis of 1236 Crohn's cases (P = 2.4 x 10(-6)). The 300A/A genotype conferred a 1.65-fold risk of Crohn's disease, with a 2.2-fold risk of ileal disease. Analysis of the interaction of ATG16L1 with CARD15 and IBD5 indicated that all 3 loci contribute independently to disease risk. Homozygosity for the risk allele at all 3 loci conferred a combined risk of 20.4 (95% confidence interval: 8.71, 47.7) for Crohn's disease. The ATG16L1 risk genotype showed a modest but significant association with ulcerative colitis (P = .026).

CONCLUSIONS

The association of ATG16L1 with Crohn's disease and possibly with ulcerative colitis supports a role for autophagy in the pathogenesis of inflammatory bowel disease.

How important is onset of action in ulcerative colitis therapy?

Pharmacotherapy is the cornerstone of management in ulcerative colitis. However, controversy remains over optimal medical strategies. Specifically, differences in the onset of action of various drug therapies are thought to influence the achievement and maintenance of remission of disease, yet this is poorly characterised. There is a wide range of recent data concerning aminosalicylates, with much debate as to the relative merits of the various formulations and delivery systems. Meta-analyses confirm the efficacy of aminosalicylates for the induction and maintenance of remission and suggest that the newer agents are comparable in efficacy to sulfasalazine. Among aminosalicylates, data from clinical trials reveal that the onset of action is earlier with balsalazide than mesalazine. Although the efficacy of the newer 5-aminosalicylate agents is no greater than that of sulfasalazine, they have better adverse effect profiles. Factors such as tolerability and adherence appear more important than onset of action in long-term maintenance. Corticosteroids have long been used in the treatment of ulcerative colitis, yet there is a paucity of data regarding this. They have a rapid onset of action but considerable systemic adverse effects. Therefore, corticosteroids are reserved for disease that fails to respond to other agents or for primary therapy in patients with severe disease, although there is no universal acceptance of a threshold at which to initiate corticosteroid treatment.Rectal preparations of both aminosalicylates and corticosteroids have been developed in an attempt to exert a more rapid and direct onset of action while minimising adverse systemic effects. In clinical trials, topical preparations of both aminosalicylates and corticosteroids are effective in inducing remission. However, patient acceptability and proximal extent of disease dictate selection of a topical agent more than concern with rate of onset.A wide range of immunomodulators have been investigated in patients with steroid-refractory ulcerative colitis. The thioguanine derivatives are the most widely used but have a limited evidence base to support this use with controlled trials providing equivocal results regarding efficacy in severe ulcerative colitis. In addition, the thioguanine derivatives have a protracted onset of action and a considerable serious adverse effect profile. Calcineurin inhibitors and methotrexate have a more rapid onset of action than the thiopurines but have even less data to support their widespread use. They are widely regarded as salvage therapy and further data are required. Regarding biological agents, infliximab revolutionised the treatment of Crohn's disease, yet results in ulcerative colitis have been disappointing. Further trials are ongoing with great anticipation for more favourable data. The practical clinical implications of any differences between the agents depend on patient satisfaction with various therapies. Noncompliance is a major concern in maintenance therapy and is probably associated with relapse. Dose administration schedules and acceptability of therapy appear to be important factors in adherence. Overall, it is not clear that onset of action has a major influence on patient adherence and addressing issues of compliance may have more direct clinical impact.

Adenocarcinoma as a complication of small bowel Crohn's disease

Carcinoma is a recognized but rare complication of small bowel Crohn's disease. This case series emphasizes the importance of considering this diagnosis in patients with small bowel Crohn's disease. We report three cases in which patients were treated for presumed exacerbations of Crohn's, but were subsequently found to have underlying small bowel adenocarcinoma. This case series will demonstrate the need for the surgical assessment of patients with long-standing symptomatic Crohn's disease that fails to settle with conservative management.

Influence of IL-6, COL1A1, and VDR gene polymorphisms on bone mineral density in Crohn's disease

BACKGROUND

Osteoporosis is an important cause of morbidity in patients with Crohn's disease. The pathogenesis of reduced bone mineral density (BMD) is multifactorial. A range of genetic factors have been implicated in other populations of patients with osteoporosis.

AIM

To investigate the influence of interleukin 6 (IL-6), collagen type 1alpha1 (COL1A1), and vitamin D receptor gene (VDR) single nucleotide polymorphisms (SNP) on BMD in patients with Crohn's disease.

PATIENTS

A cohort of 245 well characterised patients with Crohn's disease were recruited from the inflammatory bowel disease register at the Freeman Hospital and Royal Victoria Infirmary, Newcastle upon Tyne, and the Queen Elizabeth Hospital, Gateshead, UK.

METHODS

Patients were genotyped for IL-6 C-174G SNP, COL1A1 Sp1 binding site G T SNP, VDR Taq1, and Fok1 SNPs, and CARD15 R702W, G908R, and L1007fs SNPs. BMD was measured at the lumbar spine (LSP) and hip using dual energy x ray absorptiometry.

RESULTS

A total of 158 female and 87 male patients, aged 24-70 years (mean 44), were recruited. There were no significant differences in the distribution of the tested SNPs when analysed for age, body mass index, pre/post-menopausal status, smoking, or steroid use. Two hundred and thirteen patients were genotyped for the IL-6 SNP. LSP and total hip BMD was significantly lower in patients with the GG genotype (48%) than the CC genotype (15%) (p = 0.041, p = 0.014). One hundred and eighty patients were genotyped for the COL1A1 SNP. There was no significant difference in BMD at LSP. Hip BMD was significantly lower in heterozygous patients compared with homozygous wild-types (p = 0.034). There were no significant differences in BMD between genotypes for the two VDR SNPs or the CARD15 genotypes examined.

CONCLUSION

IL-6 and COL1A1 gene polymorphisms influence BMD in patients with Crohn's disease but the particular VDR gene polymorphisms studied do not have a major effect.

Review article: smoking cessation as primary therapy to modify the course of Crohn's disease

This article aims to offer an updated review of the effects of smoking on inflammatory bowel disease, and provide a review of the methods of achieving smoking cessation. A systematic review of Embase and Medline databases was conducted. Smoking causes opposing effects on ulcerative colitis and Crohn's disease. The odds ratio of developing ulcerative colitis for smokers compared with lifetime non-smokers is 0.41. Conversely, smokers with Crohn's disease have a more aggressive disease requiring more therapeutic intervention. Smoking cessation is associated with a 65% reduction in the risk of a relapse as compared with continued smokers, a similar magnitude to that obtained with immunosuppressive therapy. Although difficult to achieve smoking cessation can best be encouraged by accessing appropriate counselling services, nicotine replacement therapy and bupropion. Using a combination of these treatments there is an improved chance of success of up to 20% compared with an unassisted quit attempt. Smoking cessation unequivocally improves the course of Crohn's disease and should be a primary therapeutic aim in smokers with Crohn's disease.

Combined percutaneous and endoscopic procedures for bile duct obstruction: simultaneous and delayed techniques compared

BACKGROUND/AIMS

In patients with obstructive jaundice, when the endoscopic approach fails to achieve biliary drainage, percutaneous cannulation and combined endoscopic/percutaneous endoprosthesis insertion can be performed simultaneously or in stages. This study compared these two approaches.

METHODOLOGY

Over a three-year period 41 patients were studied. All had obstructive jaundice for which endoscopic drainage had failed. In 22 patients (group 1) percutaneous transhepatic drainage was followed a few days later by combined endoscopic and percutaneous procedure. In 19 patients (group 2) the percutaneous transhepatic drainage and combined drainage were performed at the same session. In the multiple stage group the mean interval between the first endoscopic retrograde cholangiopancreatography and final combined procedure was 9 days (SD 5.2). The groups were similar for sex, underlying pathology and reasons for failure of endoscopic approach. Group 1 patients were older 73 vs. 65 years (p < 0.05).

RESULTS

Patients in group 2 had a more rapid recovery and discharge home: mean 6 days, compared to mean 18 days from the initial procedure for group 1 (p < 0.001). Five patients died of their disease without leaving hospital (4 in group 1, 1 in group 2). In each group drainage failed in 1 patient. Complications were more common in group 1: 73% vs. 37% (p < 0.05). Pancreatitis (3 vs. 2) and septicemia (4 in group 1, 3 in group 2) were similar but group 1 had complications from the external drain: cholangitis and pyrexia in 4 patients, 3 bile leaks, and 1 catheter displacement.

CONCLUSIONS

When endoscopic drainage alone fails, a combined percutaneous/endoscopic procedure should only be performed if it can be carried out simultaneously.

Management of irritable bowel syndrome

The diagnosis of irritable bowel syndrome (IBS) is made on clinical grounds with appropriate limited investigations to exclude organic disease. IBS is common and may have a significant impact on a patient's quality of life. Psychological symptoms are common. IBS may benefit from pharmacological and non-pharmacological management. Specific measures should be directed towards the dominant symptoms of constipation or diarrhoea. Several new drugs are currently under evaluation and may prove valuable for subgroups of patients with IBS. Successful management requires a combination of reassurance and explanation about the natural history of the condition.

A double-blind comparison of balsalazide, 6.75 g daily, and sulfasalazine, 3 g daily, in patients with newly diagnosed or relapsed active ulcerative colitis

BACKGROUND

Sulfasalazine is well established in the treatment of active ulcerative colitis. Intolerance to sulfasalazine, however, is a common problem. Balsalazide has been designed to deliver 5-aminosalicylic acid to the colon without the poor tolerability of sulfasalazine.

AIM

To compare the safety and efficacy of balsalazide, 6.75 g daily, with sulfasalazine, 3 g daily, in the treatment of active ulcerative colitis of all grades of severity.

METHODS

Balsalazide and sulfasalazine were compared in a multicentre, double-blind, parallel group study over 12 weeks. Patients were stratified for disease severity and topical and/or oral steroids were co-administered where clinically necessary.

RESULTS

Fifty-seven patients were randomized: 28 to receive balsalazide and 29 to receive sulfasalazine. Significantly fewer patients withdrew from the balsalazide group due to adverse events (2/28 vs. 9/29, P=0.041). These data confirm that balsalazide is better tolerated than sulfasalazine. In patients able to tolerate the treatment, similar improvements were recorded in clinical, sigmoidoscopic and histological assessments in both treatment groups.

CONCLUSIONS

This study confirms the better tolerability of balsalazide compared to sulfasalazine, and supports the use of balsalazide in ulcerative colitis of all grades of severity.