Double-negative B cells and DNASE1L3 colocalise with microbiota in gut-associated lymphoid tissue

Intestinal homeostasis is maintained by the response of gut-associated lymphoid tissue to bacteria transported across the follicle associated epithelium into the subepithelial dome. The initial response to antigens and how bacteria are handled is incompletely understood. By iterative application of spatial transcriptomics and multiplexed single-cell technologies, we identify that the double negative 2 subset of B cells, previously associated with autoimmune diseases, is present in the subepithelial dome in health. We show that in this location double negative 2 B cells interact with dendritic cells co-expressing the lupus autoantigens DNASE1L3 and C1q and microbicides. We observe that in humans, but not in mice, dendritic cells expressing DNASE1L3 are associated with sampled bacteria but not DNA derived from apoptotic cells. We propose that fundamental features of autoimmune diseases are microbiota-associated, interacting components of normal intestinal immunity.

A retrospective cohort study: pre-operative oral enteral nutritional optimisation for Crohn's disease in a UK tertiary IBD centre

BACKGROUND

Low-quality evidence suggests that pre-operative exclusive enteral nutrition (E/EN) can improve postoperative outcomes in patients with Crohn's disease (CD). It is not standard practice in most centres.

AIMS

To test the hypothesis that pre-operative EN in patients undergoing ileal/ileocolonic surgery for CD is associated with improved postoperative outcome.

METHODS

We performed a single centre retrospective observational study comparing surgical outcomes in patients receiving pre-operative EN (≥600 kcal/day for ≥2 weeks) with those who received no nutritional optimisation. Consecutive adult patients undergoing ileal/ileocolonic resection from 2008 to 2020 were included. The primary outcome was postoperative complications <30 days. Secondary outcomes included EN tolerance, specific surgical complications, unplanned stoma formation, length of stay, length of bowel resected, readmission and biochemical/anthropometric changes.

RESULTS

300 surgeries were included comprising 96 without nutritional optimisation and 204 optimised cases: oral EN n = 173, additional PN n = 31 (4 of whom had received nasogastric/nasojejunal EN). 142/204 (69.6%) tolerated EN. 125/204 (61.3%) initiated EN in clinic. Patients in the optimised cohort were younger at operation and diagnosis, with an increased frequency of penetrating disease and exposure to antibiotics or biologics, and were more likely to undergo laparoscopic surgery. The optimised cohort had favourable outcomes on multivariate analysis: all complications [OR 0.29; 0.15-0.57, p < 0.001], surgical complications [OR 0.41; 95% CI 0.20-0.87, p = 0.02], non-surgical complications [OR 0.24 95% CI 0.11-0.52, p < 0.001], infective complications [OR 0.32; 95% CI 0.16-0.66, p = 0.001].

CONCLUSIONS

Oral EN was reasonably well tolerated and associated with a reduction in 30-day postoperative complications. Randomised controlled trials are required to confirm these findings.

Relationship Between Thiopurine S-Methyltransferase Genotype/Phenotype and 6-Thioguanine Nucleotide Levels in 316 Patients With Inflammatory Bowel Disease on 6-Thioguanine

BACKGROUND

In inflammatory bowel disease (IBD), conventional thiopurine users cease treatment in 60% of cases within 5 years, mostly because of adverse events or nonresponse. In this study, the authors aimed to investigate the role of 6-thioguanine nucleotide (TGN) measurements, geno/phenotyping of thiopurine S-methyltransferase (TPMT), and their mutual relationship with TG therapy in IBD.

METHODS

An international retrospective, multicenter cohort study was performed at 4 centers in the Netherlands (Máxima Medical Centre) and the United Kingdom (Guy's and St. Thomas' Hospital, Queen Elizabeth Hospital, and East Surrey Hospital).

RESULTS

Overall, 526 6-TGN measurements were performed in 316 patients with IBD. The median daily dosage of TG was 20 mg/d (range 10-40 mg/d), and the median duration of TG use was 21.1 months (SD, 28.0). In total, 129 patients (40.8%) had a known TPMT status. In the variant-type and wild-type TPMT genotype metabolism groups, median 6-TGN values were 1126 [interquartile range (IQR) 948-1562] and 467.5 pmol/8 × 10E8 red blood cells (RBCs) (IQR 334-593). A significant difference was observed between the 2 groups (P = 0.0001, t test). For TPMT phenotypes, in the slow, fast, and normal metabolism groups, the median 6-TGN values were 772.0 (IQR 459-1724), 296.0 (IQR 200-705), and 774.5 pmol/8 × 10E8 RBCs (IQR 500.5-981.5), with a significant difference observed between groups (P < 0.001, analysis of variance).

CONCLUSIONS

Our findings indicated that TPMT measurements at TG initiation can be useful but are not necessary for daily practice. TPMT genotypes and phenotypes are both associated with significant differences in 6-TGN levels between metabolic groups. However, the advantage of TG remains that RBC 6-TGN measurements are not crucial to monitor treatments in patients with IBD because these measurements did not correlate with laboratory result abnormalities. This presents as a major advantage in countries where patients cannot access these diagnostic tests.

An observational study of switching infliximab biosimilar: no adverse impact on inflammatory bowel disease control or drug levels with first or second switch

BACKGROUND

Biologics account for a significant cost in inflammatory bowel disease (IBD) management; however, switching from infliximab originator to its biosimilars has enabled cost saving without compromising disease control. The effects on IBD activity and infliximab trough levels of a second switch to another biosimilar are, however, uncertain.

AIMS

To assess the effects on disease activity and infliximab trough levels associated with switching from infliximab biosimilar CT-P13 to another biosimilar SB2 and compare outcomes in those switching for the first and second time.

METHODS

IBD patients on CT-P13, including some previously switched from originator, were prospectively followed during a switch to SB2. C-reactive protein (CRP), trough infliximab level and clinical disease activity indices were collected at baseline, Infusion 3 or 4 ('early' after switch), and 1 year.

RESULTS

One hundred eighty-six patients (n = 99 second switch) on stable infliximab dosing underwent switching. Compared with baseline, there was no significant change in CRP, clinical disease activity scores or median trough infliximab level at the early time point among first-switch (baseline vs early: 5.7 vs 6.6 µg/mL, P = 0.05) and second-switch (4.3 vs 4.9 µg/mL, P = 0.07) patients nor at 1 year (median infliximab trough levels, baseline vs 1 year, in first-switch [5.7 vs 5.7 µg/mL, P = 0.37] and second-switch [4.3 vs 4.7 µg/mL, P = 0.06] patients). The proportion of patients in clinical remission did not significantly change at the early (92% vs 91% at baseline, P = 0.75) or 1 year (95% vs 91% at baseline, P = 0.16) time points. There was no significant difference in time to loss of response between patients switching for the first or second time (P = 0.69).

CONCLUSIONS

Switching from one infliximab biosimilar to another had no adverse impact on infliximab trough levels, and clinical and biochemical disease activity, regardless of whether switching for the first or second time.

Human marginal zone B cell development from early T2 progenitors

B cells emerge from the bone marrow as transitional (TS) B cells that differentiate through T1, T2, and T3 stages to become naive B cells. We have identified a bifurcation of human B cell maturation from the T1 stage forming IgMhi and IgMlo developmental trajectories. IgMhi T2 cells have higher expression of α4β7 integrin and lower expression of IL-4 receptor (IL4R) compared with the IgMlo branch and are selectively recruited into gut-associated lymphoid tissue. IgMhi T2 cells also share transcriptomic features with marginal zone B cells (MZBs). Lineage progression from T1 cells to MZBs via an IgMhi trajectory is identified by pseudotime analysis of scRNA-sequencing data. Reduced frequency of IgMhi gut-homing T2 cells is observed in severe SLE and is associated with reduction of MZBs and their putative IgMhi precursors. The collapse of the gut-associated MZB maturational axis in severe SLE affirms its existence in health.

Efficacy, safety and drug survival of thioguanine as maintenance treatment for inflammatory bowel disease: a retrospective multi-centre study in the United Kingdom

BACKGROUND

Thioguanine (TG) is a thiopurine which has been used for patients with inflammatory bowel disease (IBD), who have failed azathioprine (AZA) or mercaptopurine (MP) due to adverse events or suboptimal response. Its widespread use has been hampered due to concerns about nodular regenerative hyperplasia (NRH) of the liver. The aim of this study was to investigate the long-term efficacy and safety of low-dose TG therapy in IBD patients failing AZA and MP.

METHODS

A retrospective multicentre study was performed in IBD patients who failed prior treatment with conventional thiopurines with or without following immunomodulation (thiopurine-allopurinol, biologicals, methotrexate, tacrolimus) and were subsequently treated with TG as rescue monotherapy between 2003 and 2019 at three hospitals in the United Kingdom. Clinical response, adverse events, laboratory results, imaging and liver biopsies were retrospectively collected.

RESULTS

A total of 193 patients (57% female and 64% Crohn's disease) were included, with a median daily TG dose of 20 mg (range: 20-40 mg), a median treatment duration of 23 months (IQR 10-47) and a median follow-up of 36 months (IQR 22-53). The clinical response rate at 12 months was 65 and 54% remained on TG until the end of follow-up. Adverse events consisted primarily of elevated liver tests (6%), myelotoxicity (7%) and rash (5%). NRH was histologically diagnosed in two patients and two other patients (1%) developed non-cirrhotic portal hypertension. The median 6-TGN and TPMT levels were 953 pmol/8 × 10⁵ RBC (IQR 145-1761) and 47 mu/L (IQR 34.5-96).

CONCLUSIONS

Long-term follow-up suggests that TG can be an effective and well-tolerated therapy in more than half of difficult-to-treat and multi-therapy failing IBD patients. Findings of this study indicate that TG can be used safely and the occurrence of hepatotoxicity was low. The incidence rate of NRH was within the background incidence.

Therapeutic thresholds for golimumab serum concentrations during induction and maintenance therapy in ulcerative colitis: results from the GO-LEVEL study

BACKGROUND

Significant associations between serum golimumab concentrations and favourable outcomes have been observed during both induction and maintenance therapy in ulcerative colitis (UC). However, data regarding optimal therapeutic serum golimumab concentration thresholds are limited.

AIMS

To identify optimal serum golimumab concentration thresholds during induction and maintenance treatment with golimumab.

METHODS

GO-LEVEL was an open label, phase IV study that included a prospective cohort of UC patients commencing golimumab, as well as a cross-sectional cohort receiving maintenance treatment. Patients commencing induction for active UC (defined as a simple clinical colitis activity index [SCCAI] >5 in addition to a raised faecal calprotectin [FC] >59μg/g or, raised C-reactive protein [CRP] [>5mg/L] or, Mayo endoscopic disease activity 2 or 3) were evaluated at weeks 6, 10 and 14. Patients receiving maintenance therapy were recruited either at the point of flare or during remission. Combined clinical-biochemical remission was defined as SCCAI ≤2 and FC <250μg/g. Serum golimumab concentrations were measured using a commercially available ELISA (LISATRACKER, Theradiag).

RESULTS

Thirty-nine patients were included in the induction cohort, of whom 15 (38%) achieved combined clinical-biochemical remission at week 6. The median serum golimumab concentration of those in combined clinical-biochemical remission was significantly higher than those who were not (5.0 vs 3.1 μg/mL, respectively, P = 0.03). Receiver operating characteristic (ROC) curve analysis demonstrated 3.8 μg/mL as the optimal threshold (sensitivity 0.71, specificity 0.65, area under curve [AUC] 0.72, positive predictive value [PPV] 0.59 and negative predictive value [NPV] 0.79). Sixty-three patients were included in the maintenance cohort; 31 (49%) were in combined remission, 32 (51%) were not. The median serum golimumab concentration of those in combined remission was significantly higher (2.9 vs 2.1 μg/mL, respectively, P = 0.01). ROC curve analysis demonstrated 2.4 μg/mL as the optimal threshold (sensitivity 0.68, specificity 0.66, AUC 0.68, PPV 0.65 and NPV 0.66).

CONCLUSIONS

GO-LEVEL (NCT03124121) offers further evidence regarding golimumab's exposure-response relationship. Clinicians may consider using therapeutic drug monitoring to optimise golimumab dosing aiming to achieve our suggested therapeutic thresholds of 3.8 μg/mL at week 6 and 2.4 μg/mL during maintenance.

Genetic and Inflammatory Biomarkers Classify Small Intestine Inflammation in Asymptomatic First-degree Relatives of Patients With Crohn's Disease

BACKGROUND & AIMS

Relatives of individuals with Crohn's disease (CD) carry CD-associated genetic variants and are often exposed to environmental factors that increase their risk for this disease. We aimed to estimate the utility of genotype, smoking status, family history, and biomarkers can calculate risk in asymptomatic first-degree relatives of patients with CD.

METHODS

We recruited 480 healthy first-degree relatives (full siblings, offspring or parents) of patients with CD through the Guy's and St Thomas' NHS Foundation Trust and from members of Crohn's and Colitis, United Kingdom. DNA samples were genotyped using the Immunochip. We calculated a risk score for 454 participants, based on 72 genetic variants associated with CD, family history, and smoking history. Participants were assigned to highest and lowest risk score quartiles. We assessed pre-symptomatic inflammation by capsule endoscopy and measured 22 markers of inflammation in stool and serum samples (reference standard). Two machine-learning classifiers (elastic net and random forest) were used to assess the ability of the risk factors and biomarkers to identify participants with small intestinal inflammation in the same dataset.

RESULTS

The machine-learning classifiers identified participants with pre-symptomatic intestinal inflammation: elastic net (area under the curve, 0.80; 95% CI, 0.62-0.98) and random forest (area under the curve, 0.87; 95% CI, 0.75-1.00). The elastic net method identified 3 variables that can be used to calculate odds for intestinal inflammation: combined family history of CD (odds ratio, 1.31), genetic risk score (odds ratio, 1.14), and fecal calprotectin (odds ratio, 1.04). These same 3 variables were among the 5 factors associated with intestinal inflammation in the random forest model.

CONCLUSION

Using machine learning classifiers, we found that genetic variants associated with CD, family history, and fecal calprotectin together identify individuals with pre-symptomatic intestinal inflammation who are therefore at risk for CD. A tool for detecting people at risk for CD before they develop symptoms would help identify the individuals most likely to benefit from early intervention.

Streptococcus Salivarius: A Potential Salivary Biomarker for Orofacial Granulomatosis and Crohn's Disease?

BACKGROUND

Orofacial granulomatosis (OFG) is a rare disease characterised by chronic, noncaseating, granulomatous inflammation primarily affecting the oral cavity. Histologically, it is similar to Crohn's disease (CD), and a proportion of patients have both OFG and CD. The cause of OFG remains elusive, but it has been suggested that microbial interactions may be involved. The aim of this study was to compare the salivary microbial composition of subjects with OFG and/or CD and healthy controls.

METHODS

Two hundred sixty-one subjects were recruited, of whom 78 had OFG only, 40 had both OFG and CD, 97 had CD only with no oral symptoms, and 46 were healthy controls. Bacterial community profiles were obtained by sequencing the V1-V3 region of the 16S rRNA gene.

RESULTS

There were no differences in richness or diversity of the salivary bacterial communities between patient groups and controls. The relative abundance of the Streptococcus salivarius group was raised in patients with OFG or CD only compared with controls, whereas that of the Streptococcus mitis group was lower in CD compared with both OFG and controls. One S. salivarius oligotype made the major contribution to the increased proportions seen in patients with OFG and CD.

CONCLUSIONS

The salivary microbiome of individuals with OFG and CD was similar to that found in health, although the proportions of S. salivarius, a common oral Streptococcus, were raised. One specific strain-level oligotype was found to be primarily responsible for the increased levels seen.

Current Practices in Ileal Pouch Surveillance for Patients With Ulcerative Colitis: A Multinational, Retrospective Cohort Study

BACKGROUND AND AIMS

There are no universally accepted guidelines regarding surveillance of ulcerative colitis [UC] patients after restorative proctocolectomy and ileal pouch-anal anastomosis [IPAA]. There also exists a lack of validated quality assurance standards for performing pouchoscopy. To better understand IPAA surveillance practices in the face of this clinical equipoise, we carried out a retrospective cohort study at five inflammatory bowel disease [IBD] referral centres.

METHODS

Records of patients who underwent IPAA for UC or IBD unclassified [IBDU] were reviewed, and patients with <1-year follow-up after restoration of intestinal continuity were excluded. Criteria for determining the risk of pouch dysplasia formation were collected as well as the use of pouchoscopy, biopsies, and completeness of reports.

RESULTS

We included 272 patients. Median duration of pouch follow-up was 10.5 [3.3-23.6] years; 95/272 [35%] had never undergone pouchoscopy for any indication; 191/272 [70%] had never undergone pouchoscopy with surveillance as the specific indication; and 3/26 [12%] high-risk patients had never undergone pouchoscopy. Two cases of adenocarcinoma were identified, occurring in the rectal cuff of low-risk patients. Patients under the care of surgeons appeared more likely to undergo surveillance, but rates of incomplete reporting were higher among surgeons [78%] than gastroenterologists [54%, p = 0.002].

CONCLUSIONS

We observed wide variation in surveillance of UC/IBDU-IPAA patients. In addition, the rate of neoplasia formation among 'low-risk' patients was higher than may have been expected. We therefore concur with previous recommendations that pouchoscopy be performed at 1 year postoperatively, to refine risk-stratification based on clinical factors alone. Reports should document findings in all regions of the pouch and biopsies should be taken.

Validation and Investigation of the Operating Characteristics of the Ulcerative Colitis Endoscopic Index of Severity

BACKGROUND

The Ulcerative Colitis Endoscopic Index of Severity (UCEIS) is a novel instrument to evaluate endoscopic disease activity. It has been demonstrated to outperform the more widely used Mayo endoscopic score (MES) in predicting long-term prognosis, including the need for colectomy. Despite its potential benefits, many clinicians still prefer to use MES because its operating characteristics are better defined and its grades are more readily applicable to clinical decision-making. The aims of our study were to quantify the UCEIS cutoff most closely associated with the need for treatment escalation and to perform a validation exercise using MES and clinical, biochemical, and histological measures of disease activity.

METHODS

Endoscopies performed in UC patients between November 2016 and January 2018 were retrospectively reviewed. Agreement between the UCEIS and MES was quantified using Kappa (κ) statistics. A UCEIS cutoff for treatment escalation was calculated using chi-square, receiver operating characteristic curve, and area under the curve (AUC) analyses. The Pearson correlation coefficient was used to compare linear relationships between UCEIS and clinical (Simple Clinical Colitis Activity Index [SCCAI]), biochemical (C-reactive protein [CRP]), and histological (Nancy Histological Index [NHI]) activity.

RESULTS

Two hundred one (56%) procedures documented both UCEIS and MES, demonstrating substantial agreement (κ = 0.713; P < 0.001). Treatment was escalated after 199 (56%) procedures. Receiver operating characteristic curve analysis of need for treatment escalation showed the highest sensitivity and specificity for UCEIS ≥4 (0.80 and 0.93, respectively; AUC, 0.93). Of 170 patients with a UCEIS ≥4, treatment was escalated in 159 (94%), but not for 11 (6%). Of 185 patients with a UCEIS ≤3, 40 (22%) were escalated, whereas 145 (78%) were not (P < 0.001). UCEIS correlated strongly with NHI (0.723; P < 0.001), moderately with SCCAI (0.671; P < 0.001), and weakly with CRP (0.279; P < 0.001).

CONCLUSIONS

A UCEIS ≥4 was significantly associated with treatment escalation. This cutoff could therefore be used to support clinical decision-making based on endoscopic findings. Strong and moderate correlations were found between UCEIS and histological and clinical disease activity, respectively, whereas a weak correlation was found with CRP.

10.1093/ibd/izy325_Video_1 izy325.video1 5849933952001.

Validation and Investigation of the Operating Characteristics of the Ulcerative Colitis Endoscopic Index of Severity

BACKGROUND

The Ulcerative Colitis Endoscopic Index of Severity (UCEIS) is a novel instrument to evaluate endoscopic disease activity. It has been demonstrated to outperform the more widely used Mayo endoscopic score (MES) in predicting long-term prognosis, including the need for colectomy. Despite its potential benefits, many clinicians still prefer to use MES because its operating characteristics are better defined and its grades are more readily applicable to clinical decision-making. The aims of our study were to quantify the UCEIS cutoff most closely associated with the need for treatment escalation and to perform a validation exercise using MES and clinical, biochemical, and histological measures of disease activity.

METHODS

Endoscopies performed in UC patients between November 2016 and January 2018 were retrospectively reviewed. Agreement between the UCEIS and MES was quantified using Kappa (κ) statistics. A UCEIS cutoff for treatment escalation was calculated using chi-square, receiver operating characteristic curve, and area under the curve (AUC) analyses. The Pearson correlation coefficient was used to compare linear relationships between UCEIS and clinical (Simple Clinical Colitis Activity Index [SCCAI]), biochemical (C-reactive protein [CRP]), and histological (Nancy Histological Index [NHI]) activity.

RESULTS

Two hundred one (56%) procedures documented both UCEIS and MES, demonstrating substantial agreement (κ = 0.713; P < 0.001). Treatment was escalated after 199 (56%) procedures. Receiver operating characteristic curve analysis of need for treatment escalation showed the highest sensitivity and specificity for UCEIS ≥4 (0.80 and 0.93, respectively; AUC, 0.93). Of 170 patients with a UCEIS ≥4, treatment was escalated in 159 (94%), but not for 11 (6%). Of 185 patients with a UCEIS ≤3, 40 (22%) were escalated, whereas 145 (78%) were not (P < 0.001). UCEIS correlated strongly with NHI (0.723; P < 0.001), moderately with SCCAI (0.671; P < 0.001), and weakly with CRP (0.279; P < 0.001).

CONCLUSIONS

A UCEIS ≥4 was significantly associated with treatment escalation. This cutoff could therefore be used to support clinical decision-making based on endoscopic findings. Strong and moderate correlations were found between UCEIS and histological and clinical disease activity, respectively, whereas a weak correlation was found with CRP.

10.1093/ibd/izy325_Video_1 izy325.video1 5849933952001.

Reduced CD27-IgD- B Cells in Blood and Raised CD27-IgD- B Cells in Gut-Associated Lymphoid Tissue in Inflammatory Bowel Disease

The intestinal mucosa in inflammatory bowel disease (IBD) contains increased frequencies of lymphocytes and a disproportionate increase in plasma cells secreting immunoglobulin (Ig)G relative to other isotypes compared to healthy controls. Despite consistent evidence of B lineage cells in the mucosa in IBD, little is known of B cell recruitment to the gut in IBD. Here we analyzed B cells in blood of patients with Crohn's disease (CD) and ulcerative colitis (UC) with a range of disease activities. We analyzed the frequencies of known B cell subsets in blood and observed a consistent reduction in the proportion of CD27^-IgD^- B cells expressing all Ig isotypes in the blood in IBD (independent of severity of disease and treatment) compared to healthy controls. Successful treatment of patients with biologic therapies did not change the profile of B cell subsets in blood. By mass cytometry we demonstrated that CD27^-IgD^- B cells were proportionately enriched in the gut-associated lymphoid tissue (GALT) in IBD. Since production of TNFα is a feature of IBD relevant to therapies, we sought to determine whether B cells in GALT or the CD27^-IgD^- subset in particular could contribute to pathology by secretion of TNFα or IL-10. We found that donor matched GALT and blood B cells are capable of producing TNFα as well as IL-10, but we saw no evidence that CD27^-IgD^- B cells from blood expressed more TNFα compared to other subsets. The reduced proportion of CD27^-IgD^- B cells in blood and the increased proportion in the gut implies that CD27^-IgD^- B cells are recruited from the blood to the gut in IBD. CD27^-IgD^- B cells have been implicated in immune responses to intestinal bacteria and recruitment to GALT, and may contribute to the intestinal inflammatory milieu in IBD.

Promoter orientation of the immunomodulatory Bacteroides fragilis capsular polysaccharide A (PSA) is off in individuals with inflammatory bowel disease (IBD)

Bacteroides fragilis is a member of the normal microbiota of the lower gastrointestinal tract, but some strains produce the putative tumourigenic B. fragilis toxin (BFT). In addition, B. fragilis can produce multiple capsular polysaccharides that comprise a microcapsule layer, including an immunomodulatory, zwitterionic, polysaccharide A (PSA) capable of stimulating anti-inflammatory interleukin-10 (IL-10) production. It is known that the PSA promoter can undergo inversion, thereby regulating the expression of PSA. A PCR digestion technique was used to investigate B. fragilis capsular PSA promoter orientation using human samples for the first time. It was found that approximately half of the B. fragilis population in a healthy patient population had PSA orientated in the 'ON' position. However, individuals with inflammatory bowel disease (IBD) had a significantly lower percentage of the B. fragilis population with PSA orientated 'ON' in comparison with the other patient cohorts studied. Similarly, the putative tumourigenic bft-positive B. fragilis populations were significantly associated with a lower proportion of the PSA promoter orientated 'ON'. These results suggest that the proportion of the B. fragilis population with the PSA promoter 'ON' may be an indicator of gastrointestinal health.

Spatiotemporal segregation of human marginal zone and memory B cell populations in lymphoid tissue

Human memory B cells and marginal zone (MZ) B cells share common features such as the expression of CD27 and somatic mutations in their IGHV and BCL6 genes, but the relationship between them is controversial. Here, we show phenotypic progression within lymphoid tissues as MZ B cells emerge from the mature naïve B cell pool via a precursor CD27-CD45RBMEM55+ population distant from memory cells. By imaging mass cytometry, we find that MZ B cells and memory B cells occupy different microanatomical niches in organised gut lymphoid tissues. Both populations disseminate widely between distant lymphoid tissues and blood, and both diversify their IGHV repertoire in gut germinal centres (GC), but nevertheless remain largely clonally separate. MZ B cells are therefore not developmentally contiguous with or analogous to classical memory B cells despite their shared ability to transit through GC, where somatic mutations are acquired.

Exome array analysis of adverse reactions to fluoropyrimidine-based therapy for gastrointestinal cancer

Fluoropyrimidines, including 5-fluororacil (5FU) and its pro-drug Capecitabine, are the common treatment for colorectal, breast, neck and head cancers—either as monotherapy or in combination therapy. Adverse reactions (ADRs) to the treatment are common and often result in treatment discontinuation or dose reduction. Factors contributing to ADRs, including genetic variation, are poorly characterized. We performed exome array analysis to identify genetic variants that contribute to adverse reactions. Our final dataset consisted of 504 European ancestry individuals undergoing fluoropyrimidine-based therapy for gastrointestinal cancer. A subset of 254 of these were treated with Capecitabine. All individuals were genotyped on the Illumina HumanExome Array. Firstly, we performed SNP and gene-level analyses of protein-altering variants on the array to identify novel associations the following ADRs, which were grouped into four phenotypes based on symptoms of diarrhea, mucositis, and neutropenia and hand-and-foot syndrome. Secondly, we performed detailed analyses of the HLA region on the same phenotypes after imputing the HLA alleles and amino acids. No protein-altering variants, or sets of protein-altering variants collapsed into genes, were associated with the main outcomes after Bonferroni correction. We found evidence that the HLA region was enriched for associations with Hand-and-Foot syndrome (p = 0.023), but no specific SNPs or HLA alleles were significant after Bonferroni correction. Larger studies will be required to characterize the genetic contribution to ADRs to 5FU. Future studies that focus on the HLA region are likely to be fruitful.

Thiopurines in Inflammatory Bowel Disease: New Findings and Perspectives

Thiopurines, available as azathioprine, mercaptopurine, and thioguanine, are immunomodulating agents primarily used to maintain corticosteroid-free remission in patients with inflammatory bowel disease. To provide a state-of-the-art overview of thiopurine treatment in inflammatory bowel disease, this clinical review critically summarises the available literature, as assessed by several experts in the field of thiopurine treatment and research in inflammatory bowel disease.

Metabolic retroconversion of trimethylamine N-oxide and the gut microbiota

BACKGROUND

The dietary methylamines choline, carnitine, and phosphatidylcholine are used by the gut microbiota to produce a range of metabolites, including trimethylamine (TMA). However, little is known about the use of trimethylamine N-oxide (TMAO) by this consortium of microbes.

RESULTS

A feeding study using deuterated TMAO in C57BL6/J mice demonstrated microbial conversion of TMAO to TMA, with uptake of TMA into the bloodstream and its conversion to TMAO. Microbial activity necessary to convert TMAO to TMA was suppressed in antibiotic-treated mice, with deuterated TMAO being taken up directly into the bloodstream. In batch-culture fermentation systems inoculated with human faeces, growth of Enterobacteriaceae was stimulated in the presence of TMAO. Human-derived faecal and caecal bacteria (n = 66 isolates) were screened on solid and liquid media for their ability to use TMAO, with metabolites in spent media analysed by ¹H-NMR. As with the in vitro fermentation experiments, TMAO stimulated the growth of Enterobacteriaceae; these bacteria produced most TMA from TMAO. Caecal/small intestinal isolates of Escherichia coli produced more TMA from TMAO than their faecal counterparts. Lactic acid bacteria produced increased amounts of lactate when grown in the presence of TMAO but did not produce large amounts of TMA. Clostridia (sensu stricto), bifidobacteria, and coriobacteria were significantly correlated with TMA production in the mixed fermentation system but did not produce notable quantities of TMA from TMAO in pure culture.

CONCLUSIONS

Reduction of TMAO by the gut microbiota (predominantly Enterobacteriaceae) to TMA followed by host uptake of TMA into the bloodstream from the intestine and its conversion back to TMAO by host hepatic enzymes is an example of metabolic retroconversion. TMAO influences microbial metabolism depending on isolation source and taxon of gut bacterium. Correlation of metabolomic and abundance data from mixed microbiota fermentation systems did not give a true picture of which members of the gut microbiota were responsible for converting TMAO to TMA; only by supplementing the study with pure culture work and additional metabolomics was it possible to increase our understanding of TMAO bioconversions by the human gut microbiota.

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.

Infliximab and adalimumab drug levels in Crohn's disease: contrasting associations with disease activity and influencing factors

BACKGROUND

Discriminative drug level thresholds for disease activity endpoints in patients with Crohn's disease. have been consistently demonstrated with infliximab, but not adalimumab.

AIMS

To identify threshold concentrations for infliximab and adalimumab in Crohn's disease according to different disease endpoints, and factors that influence drug levels.

METHODS

We performed a cross-sectional service evaluation of patients receiving maintenance infliximab or adalimumab for Crohn's disease. Serum drug levels were at trough for infliximab and at any time point for adalimumab. Endpoints included Harvey-Bradshaw index, C-reactive protein and faecal calprotectin. 6-tioguanine nucleotide (TGN) concentrations were measured in patients treated with thiopurines.

RESULTS

A total of 191 patients (96 infliximab, 95 adalimumab) were included. Differences in infliximab levels were observed for clinical (P=.081) and biochemical remission (P=.003) and faecal calprotectin normalisation (P<.0001) with corresponding thresholds identified on ROC analysis of 1.5, 3.4 and 5.7 μg/mL. Adalimumab levels were similar between active disease and remission regardless of the endpoint assessed. Modelling identified that higher infliximab dose, body mass index and colonic disease independently accounted for 31% of the variation in infliximab levels, and weekly dosing, albumin and weight accounted for 23% of variation in adalimumab levels. TGN levels did not correlate with drug levels.

CONCLUSIONS

Infliximab drug levels are associated with the depth of response/remission in patients with Crohn's disease, but no such relationship was observed for adalimumab. More data are needed to explain the variation in drug levels.

Utilisation of anti-TNF levels in a UK tertiary IBD centre

OBJECTIVE

To ascertain how anti-tumour necrosis factor (TNF) drug and anti-drug antibody levels testing is used in a 'real-world' setting to optimise inflammatory bowel disease (IBD) treatment.

DESIGN

Retrospective cohort study of prospectively collected patient data.

SETTING

Tertiary IBD centre in London, UK.

PATIENTS

All patients at Guy's and St Thomas' Hospitals on anti-TNF who had levels measured between the start of testing in 2012 and October 2014.

INTERVENTIONS

Anti-TNF drug and anti-drug antibody levels as part of routine monitoring.

MAIN OUTCOME MEASURES

Indication for measuring levels and changes in management made as a result of the levels.

RESULTS

330 infliximab levels were carried out in 199 patients and 143 adalimumab levels were carried out in 103 patients. Levels were primarily done in those with evidence of loss of response; 37% of infliximab levels and 52% of adalimumab levels. Levels resulted in a change in management in 26% of patients in infliximab group and 25% of patients in adalimumab group; however, this was greater in those with loss of response, 62% and 61% respectively. Anti-drug antibodies were detected in 7% of patients.

CONCLUSIONS

Our early experience has demonstrated that measuring anti-TNF drug and anti-drug antibody levels can be useful in the optimisation of IBD management. In an increasing number of patients, particularly those with evidence of loss of response, it allows early decisions to be made regarding changing therapy. It also offers the potential for significant cost-saving by preventing pointless dose escalation in the context of therapeutic levels or when high-level anti-drug antibodies are present.

Thioguanine in inflammatory bowel disease: Long-term efficacy and safety

BACKGROUND

Thioguanine (TG) is efficacious in inflammatory bowel disease (IBD), but its toxicity, particularly nodular regenerative hyperplasia (NRH) of the liver, has limited its use. We assessed the long-term clinical outcomes and safety of TG in patients whom were intolerant or refractory to conventional immunomodulators.

METHODS

This is a retrospective, single-centre study of IBD patients treated with TG from 2001-2013. Response was defined as clinical remission (Harvey-Bradshaw Index < 5 for Crohn's disease (CD), Simple Clinical Colitis Activity Index < 4 for ulcerative colitis (UC)) without corticosteroids or, if receiving anti-tumour-necrosis-factor (anti-TNF) therapy, absence of dose escalation. We recorded TG failure, withdrawal and adverse events. Patients were monitored with biochemistry, liver biopsy and/or magnetic resonance imaging (MRI).

RESULTS

54 patients (47 CD and 7 UC) whom received TG (mean dose: 27 mg/d (range: 20-40 mg/d)) as monotherapy (n = 36) or concomitantly with anti-TNF (n = 18) for a median inter-quartile range of 16 (5-37) months (126 patient-years of follow-up). 32 (59%) patients responded to TG at 6 months and 23 (43%) at 12 months. Pancreatitis did not recur amongst the 19 patients with prior thiopurine-induced pancreatitis. 16 (30%) patients ceased TG due to intolerance or toxicity (four serious); NRH was not observed. 6-thioguanine nucleotide concentrations did not correlate with efficacy nor with toxicity.

CONCLUSIONS

TG was efficacious and well tolerated in one out of two patients who had previously failed conventional immunomodulators. NRH did not occur.

Developing in vitro expanded CD45RA+ regulatory T cells as an adoptive cell therapy for Crohn's disease

BACKGROUND AND AIM

Thymus-derived regulatory T cells (Tregs) mediate dominant peripheral tolerance and treat experimental colitis. Tregs can be expanded from patient blood and were safely used in recent phase 1 studies in graft versus host disease and type 1 diabetes. Treg cell therapy is also conceptually attractive for Crohn's disease (CD). However, barriers exist to this approach. The stability of Tregs expanded from Crohn's blood is unknown. The potential for adoptively transferred Tregs to express interleukin-17 and exacerbate Crohn's lesions is of concern. Mucosal T cells are resistant to Treg-mediated suppression in active CD. The capacity for expanded Tregs to home to gut and lymphoid tissue is unknown.

METHODS

To define the optimum population for Treg cell therapy in CD, CD4(+)CD25(+)CD127(lo)CD45RA(+) and CD4(+)CD25(+)CD127(lo)CD45RA(-) Treg subsets were isolated from patients' blood and expanded in vitro using a workflow that can be readily transferred to a good manufacturing practice background.

RESULTS

Tregs can be expanded from the blood of patients with CD to potential target dose within 22-24 days. Expanded CD45RA(+) Tregs have an epigenetically stable FOXP3 locus and do not convert to a Th17 phenotype in vitro, in contrast to CD45RA(-) Tregs. CD45RA(+) Tregs highly express α4β7 integrin, CD62L and CC motif receptor 7 (CCR7). CD45RA(+) Tregs also home to human small bowel in a C.B-17 severe combined immune deficiency (SCID) xenotransplant model. Importantly, in vitro expansion enhances the suppressive ability of CD45RA(+) Tregs. These cells also suppress activation of lamina propria and mesenteric lymph node lymphocytes isolated from inflamed Crohn's mucosa.

CONCLUSIONS

CD4(+)CD25(+)CD127(lo)CD45RA(+) Tregs may be the most appropriate population from which to expand Tregs for autologous Treg therapy for CD, paving the way for future clinical trials.

Clinical relevance of DPYD variants c.1679T>G, c.1236G>A/HapB3, and c.1601G>A as predictors of severe fluoropyrimidine-associated toxicity: a systematic review and meta-analysis of individual patient data

BACKGROUND

The best-known cause of intolerance to fluoropyrimidines is dihydropyrimidine dehydrogenase (DPD) deficiency, which can result from deleterious polymorphisms in the gene encoding DPD (DPYD), including DPYD*2A and c.2846A>T. Three other variants-DPYD c.1679T>G, c.1236G>A/HapB3, and c.1601G>A-have been associated with DPD deficiency, but no definitive evidence for the clinical validity of these variants is available. The primary objective of this systematic review and meta-analysis was to assess the clinical validity of c.1679T>G, c.1236G>A/HapB3, and c.1601G>A as predictors of severe fluoropyrimidine-associated toxicity.

METHODS

We did a systematic review of the literature published before Dec 17, 2014, to identify cohort studies investigating associations between DPYD c.1679T>G, c.1236G>A/HapB3, and c.1601G>A and severe (grade ≥3) fluoropyrimidine-associated toxicity in patients treated with fluoropyrimidines (fluorouracil, capecitabine, or tegafur-uracil as single agents, in combination with other anticancer drugs, or with radiotherapy). Individual patient data were retrieved and analysed in a multivariable analysis to obtain an adjusted relative risk (RR). Effect estimates were pooled by use of a random-effects meta-analysis. The threshold for significance was set at a p value of less than 0·0167 (Bonferroni correction).

FINDINGS

7365 patients from eight studies were included in the meta-analysis. DPYD c.1679T>G was significantly associated with fluoropyrimidine-associated toxicity (adjusted RR 4·40, 95% CI 2·08-9·30, p<0·0001), as was c.1236G>A/HapB3 (1·59, 1·29-1·97, p<0·0001). The association between c.1601G>A and fluoropyrimidine-associated toxicity was not significant (adjusted RR 1·52, 95% CI 0·86-2·70, p=0·15). Analysis of individual types of toxicity showed consistent associations of c.1679T>G and c.1236G>A/HapB3 with gastrointestinal toxicity (adjusted RR 5·72, 95% CI 1·40-23·33, p=0·015; and 2·04, 1·49-2·78, p<0·0001, respectively) and haematological toxicity (adjusted RR 9·76, 95% CI 3·03-31·48, p=0·00014; and 2·07, 1·17-3·68, p=0·013, respectively), but not with hand-foot syndrome. DPYD*2A and c.2846A>T were also significantly associated with severe fluoropyrimidine-associated toxicity (adjusted RR 2·85, 95% CI 1·75-4·62, p<0·0001; and 3·02, 2·22-4·10, p<0·0001, respectively).

INTERPRETATION

DPYD variants c.1679T>G and c.1236G>A/HapB3 are clinically relevant predictors of fluoropyrimidine-associated toxicity. Upfront screening for these variants, in addition to the established variants DPYD*2A and c.2846A>T, is recommended to improve the safety of patients with cancer treated with fluoropyrimidines.

FUNDING

None.

Interleukin 6 Increases Production of Cytokines by Colonic Innate Lymphoid Cells in Mice and Patients With Chronic Intestinal Inflammation

BACKGROUND & AIMS

Innate lymphoid cells (ILCs) are a heterogeneous group of mucosal inflammatory cells that participate in chronic intestinal inflammation. We investigated the role of interleukin 6 (IL6) in inducing activation of ILCs in mice and in human beings with chronic intestinal inflammation.

METHODS

ILCs were isolated from colons of Tbx21(-/-) × Rag2(-/-) mice (TRUC), which develop colitis; patients with inflammatory bowel disease (IBD); and patients without colon inflammation (controls). ILCs were characterized by flow cytometry; cytokine production was measured by enzyme-linked immunosorbent assay and cytokine bead arrays. Mice were given intraperitoneal injections of depleting (CD4, CD90), neutralizing (IL6), or control antibodies. Isolated colon tissues were analyzed by histology, explant organ culture, and cell culture. Bacterial DNA was extracted from mouse fecal samples to assess the intestinal microbiota.

RESULTS

IL17A- and IL22-producing, natural cytotoxicity receptor-negative, ILC3 were the major subset of ILCs detected in colons of TRUC mice. Combinations of IL23 and IL1α induced production of cytokines by these cells, which increased further after administration of IL6. Antibodies against IL6 reduced colitis in TRUC mice without significantly affecting the structure of their intestinal microbiota. Addition of IL6 increased production of IL17A, IL22, and interferon-γ by human intestinal CD3-negative, IL7-receptor-positive cells, in a dose-dependent manner.

CONCLUSIONS

IL6 contributes to activation of colonic natural cytotoxicity receptor-negative, CD4-negative, ILC3s in mice with chronic intestinal inflammation (TRUC mice) by increasing IL23- and IL1α-induced production of IL17A and IL22. This pathway might be targeted to treat patients with IBD because IL6, which is highly produced in colonic tissue by some IBD patients, also increased the production of IL17A, IL22, and interferon-γ by cultured human colon CD3-negative, IL7-receptor-positive cells.

Defective macrophage handling of Escherichia coli in Crohn's disease

BACKGROUND AND AIM

Escherichia coli can be isolated from lamina propria macrophages in Crohn's disease (CD), and their intramacrophage persistence may provide a stimulus for inflammation. To further determine the contributions of macrophage dysfunction and E. coli pathogenicity to this, we aimed to compare in vitro functioning of macrophages from patients with CD and healthy controls (HC) in response to infection with CD-derived adherent-invasive E. coli (AIEC) and less pathogenic E. coli strains.

METHODS

Monocyte-derived macrophages were cultured from patients with CD and HC. Intramacrophage survival of E. coli strains (CD-derived adherent-invasive [AI] and non-AI strains and laboratory strain K-12) was compared. Macrophage cytokine release (tumor necrosis factor alpha [TNFα], interleukin [IL]-23, IL-8 and IL-10) and monocyte phagoctyosis and respiratory burst function were measured after E. coli infection. For CD patients, laboratory data were correlated with clinical phenotype, use of immunomodulation, and CD risk alleles (NOD2, IL-23R, ATG16L1 and IRGM).

RESULTS

Attenuated TNFα and IL-23 release from CD macrophages was found after infection with all E. coli strains. There was prolonged survival of CD-derived AIEC, CD-derived non-AIEC and E. coli K-12 in macrophages from CD patients compared to within those from HC. No abnormality of monocyte phagocytosis or respiratory burst function was detected in CD. Macrophage dysfunction in CD was not influenced by phenotype, use of immunomodulation or genotype.

CONCLUSIONS

CD macrophage responses to infection with E. coli are deficient, regardless of clinical phenotype, CD genotype or E. coli pathogenicity. This suggests host immunodeficiency is an important contributor to intramacrophage E. coli persistence in CD.

Klebsiella pneumoniae subsp. pneumoniae-bacteriophage combination from the caecal effluent of a healthy woman

A sample of caecal effluent was obtained from a female patient who had undergone a routine colonoscopic examination. Bacteria were isolated anaerobically from the sample, and screened against the remaining filtered caecal effluent in an attempt to isolate bacteriophages (phages). A lytic phage, named KLPN1, was isolated on a strain identified as Klebsiella pneumoniae subsp. pneumoniae (capsular type K2, rmpA (+)). This Siphoviridae phage presents a rosette-like tail tip and exhibits depolymerase activity, as demonstrated by the formation of plaque-surrounding haloes that increased in size over the course of incubation. When screened against a panel of clinical isolates of K. pneumoniae subsp. pneumoniae, phage KLPN1 was shown to infect and lyse capsular type K2 strains, though it did not exhibit depolymerase activity on such hosts. The genome of KLPN1 was determined to be 49,037 bp (50.53 %GC) in length, encompassing 73 predicted ORFs, of which 23 represented genes associated with structure, host recognition, packaging, DNA replication and cell lysis. On the basis of sequence analyses, phages KLPN1 (GenBank: KR262148) and 1513 (a member of the family Siphoviridae, GenBank: KP658157) were found to be two new members of the genus "Kp36likevirus."

A guide to oral ulceration for the medical physician

Oral ulceration is a common finding yet its classification, diagnosis and management remain a challenge for many hospital physicians. This article discusses the different types of oral ulceration and how to investigate and manage them.

Optimizing the use of thiopurines in inflammatory bowel disease

Immunomodulator drugs, of which thiopurines can be considered the backbone, are widely used in the treatment of inflammatory bowel disease. They have been shown to be highly effective and safe; however, a significant proportion of patients are deemed to have a poor response or suffer adverse reactions. Knowing how to monitor and optimize thiopurine therapy in these scenarios is crucial to effective management. We discuss the metabolism of thiopurines, the use of enzyme/metabolite testing to guide treatment, as well as strategies to circumvent toxicity and side effects, such as allopurinol coprescription. The indications, use in pregnancy, safety profile and duration of thiopurine therapy are also discussed.

A practical guide to the use of thiopurines in oral medicine

Thiopurines are widely used as first-line immunosuppressive therapies in the management of chronic inflammatory oral disease. However, despite over half a century of clinical experience, the evidence base for their use is limited. The aims of this paper were to review the evidence for the use of thiopurines in oral medicine and provide a contemporary model of thiopurine metabolism and mechanism of action and a rationale for clinical use and safe practice.

A role for gut-associated lymphoid tissue in shaping the human B cell repertoire

Transitional 2 B cells home to gut-associated lymphoid tissue and present an activated phenotype in healthy subjects, but gut immune compartments are depleted in SLE.

We have tracked the fate of immature human B cells at a critical stage in their development when the mature B cell repertoire is shaped. We show that a major subset of bone marrow emigrant immature human B cells, the transitional 2 (T2) B cells, homes to gut-associated lymphoid tissue (GALT) and that most T2 B cells isolated from human GALT are activated. Activation in GALT is a previously unknown potential fate for immature human B cells. The process of maturation from immature transitional B cell through to mature naive B cell includes the removal of autoreactive cells from the developing repertoire, a process which is known to fail in systemic lupus erythematosus (SLE). We observe that immature B cells in SLE are poorly equipped to access the gut and that gut immune compartments are depleted in SLE. Thus, activation of immature B cells in GALT may function as a checkpoint that protects against autoimmunity. In healthy individuals, this pathway may be involved in generating the vast population of IgA plasma cells and also the enigmatic marginal zone B cell subset that is poorly understood in humans.

Association between variants of PRDM1 and NDP52 and Crohn's disease, based on exome sequencing and functional studies

BACKGROUND & AIMS

Genome-wide association studies (GWAS) have identified 140 Crohn's disease (CD) susceptibility loci. For most loci, the variants that cause disease are not known and the genes affected by these variants have not been identified. We aimed to identify variants that cause CD through detailed sequencing, genetic association, expression, and functional studies.

METHODS

We sequenced whole exomes of 42 unrelated subjects with CD and 5 healthy subjects (controls) and then filtered single nucleotide variants by incorporating association results from meta-analyses of CD GWAS and in silico mutation effect prediction algorithms. We then genotyped 9348 subjects with CD, 2868 subjects with ulcerative colitis, and 14,567 control subjects and associated variants analyzed in functional studies using materials from subjects and controls and in vitro model systems.

RESULTS

We identified rare missense mutations in PR domain-containing 1 (PRDM1) and associated these with CD. These mutations increased proliferation of T cells and secretion of cytokines on activation and increased expression of the adhesion molecule L-selectin. A common CD risk allele, identified in GWAS, correlated with reduced expression of PRDM1 in ileal biopsy specimens and peripheral blood mononuclear cells (combined P = 1.6 × 10(-8)). We identified an association between CD and a common missense variant, Val248Ala, in nuclear domain 10 protein 52 (NDP52) (P = 4.83 × 10(-9)). We found that this variant impairs the regulatory functions of NDP52 to inhibit nuclear factor κB activation of genes that regulate inflammation and affect the stability of proteins in Toll-like receptor pathways.

CONCLUSIONS

We have extended the results of GWAS and provide evidence that variants in PRDM1 and NDP52 determine susceptibility to CD. PRDM1 maps adjacent to a CD interval identified in GWAS and encodes a transcription factor expressed by T and B cells. NDP52 is an adaptor protein that functions in selective autophagy of intracellular bacteria and signaling molecules, supporting the role of autophagy in the pathogenesis of CD.

Mechanism of allopurinol induced TPMT inhibition

Up to 1/5 of patients with wildtype thiopurine-S-methyltransferase (TPMT) activity prescribed azathioprine (AZA) or mercaptopurine (MP) demonstrate a skewed drug metabolism in which MP is preferentially methylated to yield methylmercaptopurine (MeMP). This is known as thiopurine hypermethylation and is associated with drug toxicity and treatment non-response. Co-prescription of allopurinol with low dose AZA/MP (25-33%) circumvents this phenotype and leads to a dramatic reduction in methylated metabolites; however, the biochemical mechanism remains unclear. Using intact and lysate red cell models we propose a novel pathway of allopurinol mediated TPMT inhibition, through the production of thioxanthine (TX, 2-hydroxymercaptopurine). In red blood cells pre-incubated with 250 μM MP for 2h prior to the addition of 250 μM TX or an equivalent volume of Earle's balanced salt solution, there was a significant reduction in the concentration of MeMP detected at 4h and 6h in cells exposed to TX (4 h, 1.68, p=0.0005, t-test). TX acts as a direct TPMT inhibitor with an apparent Ki of 0.329 mM. In addition we have confirmed that the mechanism is relevant to in vivo metabolism by demonstrating raised urinary TX levels in patients receiving combination therapy. We conclude that the formation of TX in patients receiving combination therapy with AZA/MP and allopurinol, likely explains the significant reduction of methylated metabolites due to direct TPMT inhibition.

Development of a low phenolic acid diet for the management of orofacial granulomatosis

BACKGROUND

Orofacial granulomatosis (OFG) is a rare disease of unknown cause. A cinnamon- and benzoate-free diet is successful in up to 72% of patients. Phenolic acids are among the chemical constituents restricted in this diet, which avoids some but not all of these structurally similar compounds. The present study aimed to: (i) develop a novel diet low in phenolic acids; (ii) implement this in a small clinical trial; and (iii) assess its nutritional adequacy.

METHODS

A literature review identified 10 papers quantifying phenolic acids from which 91 10-mg phenolic acid exchanges were devised. A phenolic acid exclusion diet with precautionary micronutrient supplementation was designed and implemented in 10 patients. Phenolic acids were excluded for 6 weeks and were reintroduced at a rate of one exchange every second day for 6 weeks. Wilcoxon matched pairs tests analysed disease outcomes measured by an oral disease severity scoring tool at weeks 0, 6 and 12. Nutritional adequacy was assessed, excluding micronutrient supplementation, at weeks 0 and 6, and compared intakes with dietary reference values.

RESULTS

The diet was nutritionally inadequate for a range of micronutrients. Seven of 10 patients responded. Mean [standard deviation (SD)] severity scores improved from week 0-6 [20.8 (9.39) and 10.1 (5.72); P = 0.009] and were maintained in five patients who completed the reintroduction [6.6 (3.13) and 7.2 (5.54); P = 0.713].

CONCLUSIONS

A low phenolic acid diet with micronutrient supplementation holds promise of a novel dietary treatment for OFG. Further work is required in larger studies to determine long-term outcomes.

Host-microbe interactions have shaped the genetic architecture of inflammatory bowel disease

Crohn’s disease (CD) and ulcerative colitis (UC), the two common forms of inflammatory bowel disease (IBD), affect over 2.5 million people of European ancestry with rising prevalence in other populations¹. Genome-wide association studies (GWAS) and subsequent meta-analyses of CD and UC^2,3 as separate phenotypes implicated previously unsuspected mechanisms, such as autophagy⁴, in pathogenesis and showed that some IBD loci are shared with other inflammatory diseases⁵. Here we expand knowledge of relevant pathways by undertaking a meta-analysis of CD and UC genome-wide association scans, with validation of significant findings in more than 75,000 cases and controls. We identify 71 new associations, for a total of 163 IBD loci that meet genome-wide significance thresholds. Most loci contribute to both phenotypes, and both directional and balancing selection effects are evident. Many IBD loci are also implicated in other immune-mediated disorders, most notably with ankylosing spondylitis and psoriasis. We also observe striking overlap between susceptibility loci for IBD and mycobacterial infection. Gene co-expression network analysis emphasizes this relationship, with pathways shared between host responses to mycobacteria and those predisposing to IBD.

Optimising outcome on thiopurines in inflammatory bowel disease by co-prescription of allopurinol

BACKGROUND AND AIMS

Azathioprine and mercaptopurine remain first line immunomodulatory treatments for inflammatory bowel disease. Toxicity and non-response are significant issues. Co-prescription of allopurinol with reduced-dose (25-33%) azathioprine or mercaptopurine may overcome these problems. We present the outcome of co-prescription in a large single-centre cohort.

METHOD

Patients on thiopurine/allopurinol co-prescription were identified. Indication for and outcome on combination treatment were established. Blood parameters and metabolite results were compared on single agent and combination treatment. Toxicity associated with combination treatment was sought.

RESULTS

110 patients on combination treatment were identified. Clinical remission was achieved in 60/79 (76%) of patients in whom the effect of thiopurine could be studied in isolation. 20/25 patients with hepatotoxicity tolerated combination treatment and normalised their liver function tests. 24/28 patients with atypical side effects tolerated co-therapy. 13/20 non-responders responded to combination treatment. In patients started on combination treatment as first line therapy, 15/23 achieved clinical remission. Thioguanine nucleotides were significantly higher and methylated metabolites significantly lower on combination therapy. Mean cell volume was higher and total white cell and neutrophil counts lower on combination treatment. 13 adverse events occurred, including 6 specific to co-therapy (3 rash, 2 abnormal liver function tests, 1 dosing error). All were minor and self-limiting.

CONCLUSION

This is the largest published experience of the use of allopurinol to optimise outcomes on thiopurine treatment. Combination therapy permitted successful treatment of a significant number of patients who would otherwise have been labelled as thiopurine failures. A few self-limiting side effects were encountered.

Granulomatosis with polyangiitis involves sustained mucosal inflammation that is rich in B-cell survival factors and autoantigen

OBJECTIVE

Granulomatosis with polyangiitis (GPA) is a rare chronic autoimmune disease that may be triggered by upper airway infection. ANCAs specific for PR3 that is expressed by activated neutrophils and macrophages are associated with GPA. Our aim was to investigate regional immune mechanisms that might induce or support the autoimmune response in GPA.

METHODS

Biopsy samples from 77 patients including 8 with GPA were studied by immunohistochemistry. B-cell homing subsets in blood samples from 16 patients with GPA and 11 healthy controls were studied by FACS. The distribution of B-cell clones was searched in paired biopsies and blood samples from one patient by analysing immunoglobulin heavy chain gene (IGH) junctional sequences.

RESULTS

Activated B cells were located alongside PR3-expressing cells and B-cell survival factors BAFF and APRIL in mucosa from patients with GPA. We detected APRIL production by the granulomas and giant cells. B cells were proliferating in all cases and persistent for 5 years in biopsies obtained from one patient. However, there was no evidence of B-cell clones from the mucosal biopsies circulating in peripheral blood in GPA or any numerical or proportional change in B-cell subsets expressing markers of regional homing in blood in GPA.

CONCLUSIONS

Our study illustrates chronically activated B cells alongside autoantigens and B-cell survival factors in the mucosa in GPA.

Distinct microbial populations exist in the mucosa-associated microbiota of sub-groups of irritable bowel syndrome

BACKGROUND

There is increasing evidence to support a role for the gastrointestinal microbiota in the etiology of irritable bowel syndrome (IBS). Given the evidence of an inflammatory component to IBS, the mucosa-associated microbiota potentially play a key role in its pathogenesis. The objectives were to compare the mucosa-associated microbiota between patients with diarrhea predominant IBS (IBS-D), constipation predominant IBS (IBS-C) and controls using fluorescent in situ hybridization and to correlate specific bacteria groups with individual IBS symptoms.

METHODS

Forty-seven patients with IBS (27 IBS-D and 20 IBS-C) and 26 healthy controls were recruited to the study. Snap-frozen rectal biopsies were taken at colonoscopy and bacterial quantification performed by hybridizing frozen sections with bacterial-group specific oligonucleotide probes.

KEY RESULTS

Patients with IBS had significantly greater numbers of total mucosa-associated bacteria per mm of rectal epithelium than controls [median 218 (IQR - 209) vs 128 (121) P = 0.007], and this was chiefly comprised of bacteroides IBS [69 (67) vs 14 (41) P = 0.001] and Eubacterium rectale-Clostridium coccoides [52 (58) vs 25 (35) P = 0.03]. Analysis of IBS sub-groups demonstrated that bifidobacteria were lower in the IBS-D group than in the IBS-C group and controls [24 (32) vs 54 (88) vs 32 (35) P = 0.011]. Finally, amongst patients with IBS, the maximum number of stools per day negatively correlated with the number of mucosa-associated bifidobacteria (P < 0.001) and lactobacilli (P = 0.002).

CONCLUSIONS & INFERENCES

The mucosa-associated microbiota in patients with IBS is significantly different from healthy controls with increases in bacteroides and clostridia and a reduction in bifidobacteria in patients with IBS-D.

Review article: cinnamon- and benzoate-free diet as a primary treatment for orofacial granulomatosis

BACKGROUND

Orofacial granulomatosis is a rare chronic granulomatous inflammatory disease of the lips, face and mouth. The aetiology remains unclear but may involve an allergic component. Improvements have been reported with cinnamon- and benzoate-free diets.

AIMS

To explore the prevalence of compound and food sensitivity and examine the dietary treatments used in orofacial granulomatosis.

METHODS

A comprehensive literature search was carried out and relevant studies from January 1933 to January 2010 were identified using the electronic database search engines; AGRIS 1991-2008, AMED 1985-2008, British Nursing and Index archive 1985-2008, EMBASE 1980-2008, evidence based medicine review databases (e.g. Cochrane DSR), International Pharmaceutical and Medline 1950-2008.

RESULTS

Common sensitivities identified, predominantly through patch testing, were to benzoic acid (36%) food additives (33%), perfumes and flavourings (28%), cinnamaldehyde (27%), cinnamon (17%), benzoates (17%) and chocolate (11%). The cinnamon- and benzoate-free diet has been shown to provide benefit in 54-78% of patients with 23% requiring no adjunctive therapies. A negative or positive patch test result to cinnamaldehyde, and benzoates did not predict dietary outcome. The most concentrated source of benzoate exposure is from food preservatives. Use of liquid enteral formulas can offer a further dietary therapy, particularly in children with orofacial granulomatosis.

CONCLUSION

Management of orofacial granulomatosis is challenging but cinnamon- and benzoate-free diets appear to have a definite role to play.

Distinguishing orofacial granulomatosis from crohn's disease: two separate disease entities?

BACKGROUND

Orofacial granulomatosis (OFG) is a rare chronic inflammatory disease of unknown etiology sharing histological features with Crohn's disease (CD). This study aimed to 1) define the clinical presentation of OFG, 2) establish differentiating features for those with CD, 3) examine if onset of OFG is predictive of CD, and 4) establish differentiating features for children.

METHODS

Data were extracted from medical notes (n = 207) for demographics, clinical features, blood parameters, diagnosis of CD, and treatment's for patients with OFG.

RESULTS

Ninety-seven patients (47%) were female. The lips (184/203; 91%) and buccal mucosa (151/203; 74%) were mainly affected. Forty-six (22%) had intestinal CD. Ulcers (24/46; 46% versus 29/159; 15%, P = <0.001) were more common in patients with CD as was a raised C-reactive protein (24/33; 73% versus 60/122; 49%, P = 0.016) and abnormal full blood count (19/41; 46% versus 35/150; 23%). The buccal-sulcus (12/44; 27% versus 20/158; 13%, P = 0.019) was more often affected in those with CD. Half the patients with CD were diagnosed prior to onset of OFG. The remainder were diagnosed after. The incidence of CD is similar for children (16/69; 23%) and adults (29/132; 22%), although oral onset in childhood is more likely to occur prior to diagnosis of CD.

CONCLUSIONS

OFG mainly presents in young adults with lip and buccal involvement. Abnormalities in inflammatory markers, hematology and oral features of ulceration, and buccal-sulcal involvement are factors more commonly associated with CD. Initial presentation of OFG does not necessarily predict development of CD, although this is more likely in childhood.

Randomised, double-blind, placebo-controlled trial of fructo-oligosaccharides in active Crohn's disease

INTRODUCTION

The commensal intestinal microbiota drive the inflammation associated with Crohn's disease. However, bacteria such as bifidobacteria and Faecalibacterium prausnitzii appear to be immunoregulatory. In healthy subjects the intestinal microbiota are influenced by prebiotic carbohydrates such as fructo-oligosaccharides (FOS). Preliminary data suggest that FOS increase faecal bifidobacteria, induce immunoregulatory dendritic cell (DC) responses and reduce disease activity in patients with Crohn's disease.

AIMS AND METHODS

To assess the impact of FOS in patients with active Crohn's disease using an adequately powered randomised double-blind placebo-controlled trial with predefined clinical, microbiological and immunological end points. Patients with active Crohn's disease were randomised to 15 g/day FOS or non-prebiotic placebo for 4 weeks. The primary end point was clinical response at week 4 (fall in Crohn's Disease Activity Index of ≥ 70 points) in the intention-to-treat (ITT) population.

RESULTS

103 patients were randomised to receive FOS (n = 54) or placebo (n = 49). More patients receiving FOS (14 (26%) vs 4 (8%); p = 0.018) withdrew before the 4-week end point. There was no significant difference in the number of patients achieving a clinical response between the FOS and placebo groups in the ITT analysis (12 (22%) vs 19 (39%), p = 0.067). Patients receiving FOS had reduced proportions of interleukin (IL)-6-positive lamina propria DC and increased DC staining of IL-10 (p < 0.05) but no change in IL-12p40 production. There were no significant differences in the faecal concentration of bifidobacteria and F prausnitzii between the groups at baseline or after the 4-week intervention.

CONCLUSION

An adequately powered placebo-controlled trial of FOS showed no clinical benefit in patients with active Crohn's disease, despite impacting on DC function. ISRCTN50422530.