Phage-display immunoprecipitation sequencing of the antibody epitope repertoire in inflammatory bowel disease reveals distinct antibody signatures.

Inflammatory bowel diseases (IBDs), e.g., Crohn's disease (CD) and ulcerative colitis (UC), are chronic immune-mediated inflammatory diseases. A comprehensive overview of an IBD-specific antibody epitope repertoire is, however, lacking. Using high-throughput phage-display immunoprecipitation sequencing (PhIP-Seq), we identified antibodies against 344,000 antimicrobial, immune, and food antigens in 497 individuals with IBD compared with 1,326 controls. IBD was characterized by 373 differentially abundant antibody responses (202 overrepresented and 171 underrepresented), with 17% shared by both IBDs, 55% unique to CD, and 28% unique to UC. Antibody reactivities against bacterial flagellins dominated in CD and were associated with ileal involvement, fibrostenotic disease, and anti-Saccharomyces cerevisiae antibody positivity, but not with fecal microbiome composition. Antibody epitope repertoires accurately discriminated CD from controls (area under the curve [AUC] = 0.89), and similar discrimination was achieved when using only ten antibodies (AUC = 0.87). Individuals with IBD thus show a distinct antibody repertoire against selected peptides, allowing clinical stratification and discovery of immunological targets.

Interobserver agreement of current and new proposed endoscopic scores for postoperative recurrence in Crohn's disease.

BACKGROUND AND AIMS: The modified Rutgeerts score (mRS) is widely used for the assessment of endoscopic postoperative recurrence (ePOR) in Crohn's disease (CD) after ileocolic resection to guide therapeutic decisions. To improve the validity and prognostic value of this endoscopic assessment, 2 new scores have been proposed. This study assessed the interobserver agreement of the current score (mRS) and the new endoscopic score for ePOR in CD. METHODS: Sixteen Dutch academic and nonacademic inflammatory bowel disease specialists assessed endoscopic videos (n = 71) of postoperative CD patients (n = 66) retrieved from 9 Dutch centers. Each video was assessed for degree of inflammation by 4 gastroenterologists using the mRS and the new proposed endoscopic score: the REMIND score (separate score of anastomosis and neoterminal ileum) and the updated Rutgeerts score (assessment of lesions at the anastomotic line, ileal inlet, ileal body, and neoterminal ileum). In addition, lesions at the ileal body, ileal inlet, neoterminal ileum, and colonic and/or ileal blind loop were separately assessed. Interobserver agreement was assessed by using Fleiss' weighted kappa. RESULTS: Fleiss' weighted kappa for the mRS was .67 (95% confidence interval [CI], .59-.74). The weighted kappa for the REMIND score was .73 (95% CI, .65-.80) for lesions in the neoterminal ileum and .46 (95% CI, .35-.58) for anastomotic lesions. The weighted kappa for the updated Rutgeerts score was .69 (95% CI, .62-.77). The weighted kappa for lesions in the ileal body, ileal inlet, neoterminal ileum, and colonic and ileal blind loop was .61 (95% CI, .49-.73), .63 (95% CI, .54-.72), .61 (95% CI, .49-.74), .83 (95% CI, .62-1.00) and .68 (95% CI, .46-.89), respectively. CONCLUSIONS: The interobserver agreement of the mRS is substantial. Similarly, the interobserver agreement is substantial for the updated Rutgeerts score. According to the REMIND score, the interobserver agreement was substantial for lesions in the neoterminal ileum, although only moderate for anastomotic lesions. Because therapeutic decisions in clinical practice are based on these assessments, and these scores are used as outcome measure in clinical studies, further improvement of the interobserver agreement is essential.

Superior Effectiveness of Tofacitinib Compared to Vedolizumab in Anti-TNF-experienced Ulcerative Colitis Patients: A Nationwide Dutch Registry Study.

BACKGROUND & AIMS: Clinicians face difficulty in when and in what order to position biologics and Janus kinase inhibitors in patients with anti-tumor necrosis factor-alpha (TNF) refractory ulcerative colitis (UC). We aimed to compare the effectiveness and safety of vedolizumab and tofacitinib in anti-TNF-exposed patients with UC in our prospective nationwide Initiative on Crohn and Colitis Registry. METHODS: Patients with UC who failed anti-TNF treatment and initiated vedolizumab or tofacitinib treatment were identified in the Initiative on Crohn and Colitis Registry in the Netherlands. We selected patients with both clinical as well as biochemical or endoscopic disease activity at initiation of therapy. Patients previously treated with vedolizumab or tofacitinib were excluded. Corticosteroid-free clinical remission (Simple Clinical Colitis Activity Index ≤2), biochemical remission (C-reactive protein ≤5 mg/L or fecal calprotectin ≤250 µg/g), and safety outcomes were compared after 52 weeks of treatment. Inverse propensity score-weighted comparison was used to adjust for confounding and selection bias. RESULTS: Overall, 83 vedolizumab- and 65 tofacitinib-treated patients were included. Propensity score-weighted analysis showed that tofacitinib-treated patients were more likely to achieve corticosteroid-free clinical remission and biochemical remission at weeks 12, 24, and 52 compared with vedolizumab-treated patients (odds ratio [OR], 6.33; 95% confidence interval [CI], 3.81-10.50; P < .01; OR, 3.02; 95% CI, 1.89-4.84; P < .01; and OR, 1.86; 95% CI, 1.15-2.99; P = .01; and OR, 3.27; 95% CI, 1.96-5.45; P < .01; OR, 1.87; 95% CI, 1.14-3.07; P = .01; and OR, 1.81; 95% CI, 1.06-3.09; P = .03, respectively). There was no difference in infection rate or severe adverse events. CONCLUSIONS: Tofacitinib was associated with superior effectiveness outcomes compared with vedolizumab in anti-TNF-experienced patients with UC along with comparable safety outcomes.

Cigarette Smoke Increases Risk for Colorectal Neoplasia in Inflammatory Bowel Disease.

BACKGROUND & AIMS: Patients with inflammatory bowel disease are at increased risk of colorectal neoplasia (CRN) due to mucosal inflammation. As current surveillance guidelines form a burden on patients and healthcare costs, stratification of high-risk patients is crucial. Cigarette smoke reduces inflammation in ulcerative colitis (UC) but not Crohn's disease (CD) and forms a known risk factor for CRN in the general population. Due to this divergent association, the effect of smoking on CRN in IBD is unclear and subject of this study. METHODS: In this retrospective cohort study, 1,386 IBD patients with previous biopsies analyzed and reported in the PALGA register were screened for development of CRN. Clinical factors and cigarette smoke were evaluated. Patients were stratified for guideline-based risk of CRN. Cox-regression modeling was used to estimate the effect of cigarette smoke and its additive effect within the current risk stratification for prediction of CRN. RESULTS: 153 (11.5%) patients developed CRN. Previously described risk factors, i.e. first-degree family member with CRN in CD (p-value=.001), presence of post-inflammatory polyps in UC (p-value=.005), were replicated. Former smoking increased risk of CRN in UC (HR 1.73; 1.05-2.85), whereas passive smoke exposure yielded no effect. For CD, active smoking (2.20; 1.02-4.76) and passive smoke exposure (1.87; 1.09-3.20) significantly increased CRN risk. Addition of smoke exposure to the current risk-stratification model significantly improved model fit for CD. CONCLUSIONS: This study is the first to describe the important role of cigarette smoke in CRN development in IBD patients. Adding this risk factor improves the current risk stratification for CRN surveillance strategies.

Serological Biomarkers of Extracellular Matrix Turnover and Neutrophil Activity Are Associated with Long-Term Use of Vedolizumab in Patients with Crohn's Disease.

Crohn's disease (CD) is a relapsing-remitting inflammatory disease of the gastrointestinal (GI) tract characterized by increased extracellular matrix (ECM) remodeling. The introduction of the α4ß7-integrin inhibitor vedolizumab (VEDO) has improved disease management, although there is a high rate of primary non-response in patients with CD. We studied whether ECM biomarkers of neutrophil activity and mucosal damage could predict long-term response to VEDO in patients with CD. Serum levels of human neutrophil elastase (HNE)-derived fragments of calprotectin (CPa9-HNE), and matrix metalloproteinase (MMP)-derived fragments of type I (C1M), III (C3M), IV (C4M), and VI (C6Ma3) collagen, type III collagen formation (PRO-C3), basement membrane turnover (PRO-C4) and T-cell activity (C4G), were measured using protein fingerprint assays in patients with CD (n = 32) before VEDO therapy. Long-term response was defined as VEDO treatment of at least 12 months. CPa9-HNE was significantly increased at baseline in non-responders compared with responders (p < 0.05). C1M, C3M, C4M, C6Ma3, and PRO-C4 were also significantly increased at baseline in non-responders compared with responders (all p < 0.05). All biomarkers were associated with response to VEDO (all p < 0.05). To conclude, baseline levels of serum biomarkers for neutrophil activity and mucosal damage are linked to the pathology of CD, and are associated with long-term use of VEDO in patients with CD. Therefore, these biomarkers warrant further validation and could aid in therapeutic decision-making concerning vedolizumab therapy.

Whole exome sequencing analyses reveal gene-microbiota interactions in the context of IBD.

OBJECTIVE: Both the gut microbiome and host genetics are known to play significant roles in the pathogenesis of IBD. However, the interaction between these two factors and its implications in the aetiology of IBD remain underexplored. Here, we report on the influence of host genetics on the gut microbiome in IBD. DESIGN: To evaluate the impact of host genetics on the gut microbiota of patients with IBD, we combined whole exome sequencing of the host genome and whole genome shotgun sequencing of 1464 faecal samples from 525 patients with IBD and 939 population-based controls. We followed a four-step analysis: (1) exome-wide microbial quantitative trait loci (mbQTL) analyses, (2) a targeted approach focusing on IBD-associated genomic regions and protein truncating variants (PTVs, minor allele frequency (MAF) >5%), (3) gene-based burden tests on PTVs with MAF <5% and exome copy number variations (CNVs) with site frequency <1%, (4) joint analysis of both cohorts to identify the interactions between disease and host genetics. RESULTS: We identified 12 mbQTLs, including variants in the IBD-associated genes IL17REL, MYRF, SEC16A and WDR78. For example, the decrease of the pathway acetyl-coenzyme A biosynthesis, which is involved in short chain fatty acids production, was associated with variants in the gene MYRF (false discovery rate <0.05). Changes in functional pathways involved in the metabolic potential were also observed in participants carrying rare PTVs or CNVs in CYP2D6, GPR151 and CD160 genes. These genes are known for their function in the immune system. Moreover, interaction analyses confirmed previously known IBD disease-specific mbQTLs in TNFSF15. CONCLUSION: This study highlights that both common and rare genetic variants affecting the immune system are key factors in shaping the gut microbiota in the context of IBD and pinpoints towards potential mechanisms for disease treatment.

Exome sequencing in patient-parent trios suggests new candidate genes for early-onset primary sclerosing cholangitis.

BACKGROUND & AIMS: Primary sclerosing cholangitis (PSC) is a rare bile duct disease strongly associated with inflammatory bowel disease (IBD). Whole-exome sequencing (WES) has contributed to understanding the molecular basis of very early-onset IBD, but rare protein-altering genetic variants have not been identified for early-onset PSC. We performed WES in patients diagnosed with PSC ≤ 12 years to investigate the contribution of rare genetic variants to early-onset PSC. METHODS: In this multicentre study, WES was performed on 87 DNA samples from 29 patient-parent trios with early-onset PSC. We selected rare (minor allele frequency < 2%) coding and splice-site variants that matched recessive (homozygous and compound heterozygous variants) and dominant (de novo) inheritance in the index patients. Variant pathogenicity was predicted by an in-house developed algorithm (GAVIN), and PSC-relevant variants were selected using gene expression data and gene function. RESULTS: In 22 of 29 trios we identified at least 1 possibly pathogenic variant. We prioritized 36 genes, harbouring a total of 54 variants with predicted pathogenic effects. In 18 genes, we identified 36 compound heterozygous variants, whereas in the other 18 genes we identified 18 de novo variants. Twelve of 36 candidate risk genes are known to play a role in transmembrane transport, adaptive and innate immunity, and epithelial barrier function. CONCLUSIONS: The 36 candidate genes for early-onset PSC need further verification in other patient cohorts and evaluation of gene function before a causal role can be attributed to its variants.

Environmental factors associated with biological use and surgery in inflammatory bowel disease.

BACKGROUND AND AIM: While major efforts were made studying the complex etiology of inflammatory bowel disease (IBD) including environmental factors, less is known about underlying causes leading to the heterogeneous and highly variable course of disease. As cigarette smoking cessation is the best-known environmental factor with beneficial effect in Crohn's disease (CD), more exposome factors are likely involved. Further insights into the role of the exposome in heterogeneity of disease might not only further knowledge of underlying pathways, but also allow for better risk stratification. METHODS: Seven hundred twenty-eight IBD patients completed the validated Groningen IBD Environmental Questionnaire, collecting exposome data for 93 exposome factors. Associations with disease course, that is, for need for surgery or biological therapy, were evaluated using univariate and multivariate-adjusted logistic regression modeling. RESULTS: No significant associations were seen after Bonferroni correction. However, 11 novel exposome factors were identified with P < 0.05. Two factors were associated with course of CD and ulcerative colitis (UC): beer (CD OR0.3/UC OR0.3) and cannabis (0.5/2.2). While in CD, carpet flooring (0.5) was associated with biological use, and four factors were associated with surgery: working shifts (1.8), appendectomy (2.4), frequent tooth brushing (2.8), and large household size (0.1). For UC, migrants more often required biologicals (10.2). Childhood underweight (3.4), amphetamine use (6.2), and cocaine use (4.8) were associated with surgery. Five factors were replicated. CONCLUSIONS: We identified 16 environmental factors nominally associated with biological use and surgery in established IBD. These new insights form an important stepping stone to guide research on biological pathways involved, risk stratification, tailor-made interventions, and preventive strategies in IBD.

A Combined mRNA- and miRNA-Sequencing Approach Reveals miRNAs as Potential Regulators of the Small Intestinal Transcriptome in Celiac Disease.

Celiac disease (CeD) is triggered by gluten and results in inflammation and villous atrophy of the small intestine. We aimed to explore the role of miRNA-mediated deregulation of the transcriptome in CeD. Duodenal biopsies of CeD patients (n = 33) and control subjects (n = 10) were available for miRNA-sequencing, with RNA-sequencing also available for controls (n = 5) and CeD (n = 6). Differential expression analysis was performed to select CeD-associated miRNAs and genes. MiRNA‒target transcript pairs selected from public databases that also displayed a strong negative expression correlation in the current dataset (R < -0.7) were used to construct a CeD miRNA‒target transcript interaction network. The network includes 2030 miRNA‒target transcript interactions, including 423 experimentally validated pairs. Pathway analysis found that interactions are involved in immune-related pathways (e.g., interferon signaling) and metabolic pathways (e.g., lipid metabolism). The network includes 13 genes previously prioritized to be causally deregulated by CeD-associated genomic variants, including STAT1. CeD-associated miRNAs might play a role in promoting inflammation and decreasing lipid metabolism in the small intestine, thereby contributing unbalanced cell turnover in the intestinal crypt. Some CeD-associated miRNAs deregulate genes that are also affected by genomic CeD-risk variants, adding an additional layer of complexity to the deregulated transcriptome in CeD.

Latent cytomegalovirus infection does not influence long-term disease outcomes in inflammatory bowel disease, but is associated with later onset of disease.

OBJECTIVES: Cytomegalovirus (CMV) infection is common in the general population. CMV infection negatively affects disease course in transplant recipients and HIV patients. Whereas primary CMV infections may occur sporadically in seronegative patients, all seropositive patients with inflammatory bowel syndrome (IBD) are at risk for CMV reactivation due to the inflammatory mucosal and use of immunosuppressive medication. It is unclear whether latent CMV infection, and risk of reactivations, influences long-term disease outcomes. In this study, we aim to explore whether CMV infection affects disease outcomes in IBD patients. METHODS: We performed a cross-sectional cohort study with 1404 patients with IBD from a single center. Clinical characteristics and disease outcomes were prospectively collected. We scrutinized CMV serology test results and performed additional CMV serology testing if serum was available. RESULTS: Out of 699 IBD patients with CMV serology, 303 (43.3%) were seropositive, comparable to the general Dutch population. CMV seropositivity was associated with older age, longer IBD disease duration, non-Western origin, birth outside the Netherlands and a lower educational level (p-values ≤ .004). CMV seropositivity was not associated with more complicated long-term disease outcomes of IBD (p-values > .05). Seropositive patients presented with symptoms and were diagnosed at an older age compared to seronegative patients (p-values < .01). CONCLUSIONS: CMV seropositivity does not influence disease outcomes of IBD patients and seems to be associated with a delay in IBD onset. Guidelines regarding CMV screening in patients with IBD are currently based on a low level of evidence. These data support the recommendation that routine CMV serology measurement is not necessary in the clinical care of IBD.

Molecular Biomarkers for Celiac Disease: Past, Present and Future.

Celiac disease (CeD) is a complex immune-mediated disorder that is triggered by dietary gluten in genetically predisposed individuals. CeD is characterized by inflammation and villous atrophy of the small intestine, which can lead to gastrointestinal complaints, malnutrition, and malignancies. Currently, diagnosis of CeD relies on serology (antibodies against transglutaminase and endomysium) and small-intestinal biopsies. Since small-intestinal biopsies require invasive upper-endoscopy, and serology cannot predict CeD in an early stage or be used for monitoring disease after initiation of a gluten-free diet, the search for non-invasive biomarkers is ongoing. Here, we summarize current and up-and-coming non-invasive biomarkers that may be able to predict, diagnose, and monitor the progression of CeD. We further discuss how current and emerging techniques, such as (single-cell) transcriptomics and genomics, can be used to uncover the pathophysiology of CeD and identify non-invasive biomarkers.

Interplay of host genetics and gut microbiota underlying the onset and clinical presentation of inflammatory bowel disease.

OBJECTIVE: Patients with IBD display substantial heterogeneity in clinical characteristics. We hypothesise that individual differences in the complex interaction of the host genome and the gut microbiota can explain the onset and the heterogeneous presentation of IBD. Therefore, we performed a case-control analysis of the gut microbiota, the host genome and the clinical phenotypes of IBD. DESIGN: Stool samples, peripheral blood and extensive phenotype data were collected from 313 patients with IBD and 582 truly healthy controls, selected from a population cohort. The gut microbiota composition was assessed by tag-sequencing the 16S rRNA gene. All participants were genotyped. We composed genetic risk scores from 11 functional genetic variants proven to be associated with IBD in genes that are directly involved in the bacterial handling in the gut: NOD2, CARD9, ATG16L1, IRGM and FUT2. RESULTS: Strikingly, we observed significant alterations of the gut microbiota of healthy individuals with a high genetic risk for IBD: the IBD genetic risk score was significantly associated with a decrease in the genus Roseburia in healthy controls (false discovery rate 0.017). Moreover, disease location was a major determinant of the gut microbiota: the gut microbiota of patients with colonic Crohn's disease (CD) is different from that of patients with ileal CD, with a decrease in alpha diversity associated to ileal disease (p=3.28×10-13). CONCLUSIONS: We show for the first time that genetic risk variants associated with IBD influence the gut microbiota in healthy individuals. Roseburia spp are acetate-to-butyrate converters, and a decrease has already been observed in patients with IBD.

Cell Specific eQTL Analysis without Sorting Cells.

The functional consequences of trait associated SNPs are often investigated using expression quantitative trait locus (eQTL) mapping. While trait-associated variants may operate in a cell-type specific manner, eQTL datasets for such cell-types may not always be available. We performed a genome-environment interaction (GxE) meta-analysis on data from 5,683 samples to infer the cell type specificity of whole blood cis-eQTLs. We demonstrate that this method is able to predict neutrophil and lymphocyte specific cis-eQTLs and replicate these predictions in independent cell-type specific datasets. Finally, we show that SNPs associated with Crohn's disease preferentially affect gene expression within neutrophils, including the archetypal NOD2 locus.

Vaginal delivery in women with perianal Crohn's disease: why not?

BACKGROUND: Pregnant women with active perianal Crohn's disease indicate a cesarean delivery according to the current European Crohn's and Colitis Organisation guidelines. This advice is based on the assumption that vaginal delivery leads to exacerbation of perianal disease and worsening of fecal continence. However, there is no strong evidence to support this. OBJECTIVE: This study aims to examine the effects of the delivery method on perianal disease progression and fecal incontinence in women with perianal Crohn's disease. STUDY DESIGN: In this retrospective cohort study, 102 women were selected from the 1000 inflammatory bowel disease cohort of a tertiary hospital in the Netherlands. All women are aged >18 years, have perianal Crohn's disease, and have given birth. In addition, all women completed a questionnaire. Fecal continence was scored using the Vaizey score. Using SPSS, descriptive analysis and linear regression analysis were performed, and P values <.05 were considered statistically significant. RESULTS: The cesarean delivery rate within our cohort was 19.5%. Within the group of women who delivered at least one child vaginally (n=84), 25.5% reported alteration of fecal continence, compared with 13.1% in women who only had cesarean delivery (n=18). After a mean follow-up of 15 years, the median Vaizey score within the cesarean delivery group was 5, compared with 7 in the vaginal delivery group. Within the vaginal delivery group, 18.8% reported perianal disease progression, compared with 22.2% in the cesarean delivery group. No significant relation between mode of delivery and fecal continence or perianal disease progression was found (B, 0,97 [-1,19 to 3,14], P=.38). CONCLUSION: Fecal incontinence and perianal disease progression after vaginal delivery in Crohn's disease women with active perianal fistula is not significantly increased in this retrospective cohort. This study opens the discussion for more tailored obstetric advice in women with perianal Crohn's disease.

Clinical Validation of a Capillary Blood Home-Based Self-Sampling Technique for Monitoring of Infliximab, Vedolizumab, and C-Reactive Protein Concentrations in Patients With Inflammatory Bowel Disease.

BACKGROUND: Therapeutic drug monitoring provides important guidance for treatment of patients with inflammatory bowel disease (IBD) and could help to early identify treatment failure. This study aimed to validate a finger prick-based capillary blood sampling technique to measure biological trough levels and C-reactive protein (CRP) and evaluate patient performance and -support. METHODS: In this prospective cohort study, patients with IBD receiving infliximab (IFX) or vedolizumab (VEDO) therapy performed finger prick-based capillary blood sampling at home. Additionally, blood was collected through routinely performed in-hospital venepuncture prior to biological infusion. IFX, VEDO, and CRP concentrations were measured by enzyme-linked immunosorbent assay. The concordance between methods was statistically evaluated and a survey was conducted to assess practicality and patient support. RESULTS: In total, 81 patients (46 IFX, 35 VEDO) were enrolled. Mean differences between both methods were 0.42 (95% confidence interval, -1.74 to 2.58) µg/mL for IFX and 0.72 (95% confidence interval, -5.50 to 6.94) µg/mL for VEDO. Passing-Bablok regressions demonstrated no evidence for systematic or proportional biases. Venous and capillary IFX (ρ = 0.96, P < .001) and VEDO (ρ = 0.97, P < .001) levels strongly correlated and showed high intermethod agreement (Cohen's kappa: IFX = 0.82; VEDO = 0.94). Similarly, venous and capillary CRP levels were strongly correlated (ρ = 0.99, P < .001). Most patients (>95%) were able to successfully perform the self-sampling at home without prior instructions. CONCLUSIONS: This study clinically validated a finger prick-based capillary blood self-sampling technique allowing concomitant home monitoring of biological levels and CRP for patients with IBD, who reported substantial support, tolerability, and practicality.

Mucosal host-microbe interactions associate with clinical phenotypes in inflammatory bowel disease.

Disrupted host-microbe interactions at the mucosal level are key to the pathophysiology of IBD. This study aimed to comprehensively examine crosstalk between mucosal gene expression and microbiota in patients with IBD. To study tissue-specific interactions, we perform transcriptomic (RNA-seq) and microbial (16S-rRNA-seq) profiling of 697 intestinal biopsies (645 derived from 335 patients with IBD and 52 from 16 non-IBD controls). Mucosal gene expression patterns in IBD are mainly determined by tissue location and inflammation, whereas the mucosal microbiota composition shows a high degree of individual specificity. Analysis of transcript-bacteria interactions identifies six distinct groups of inflammation-related pathways that are associated with intestinal microbiota (adjusted P < 0.05). An increased abundance of Bifidobacterium is associated with higher expression of genes involved in fatty acid metabolism, while Bacteroides correlates with increased metallothionein signaling. In patients with fibrostenosis, a transcriptional network dominated by immunoregulatory genes is associated with Lachnoclostridium bacteria in non-stenotic tissue (adjusted P < 0.05), while being absent in CD without fibrostenosis. In patients using TNF-α-antagonists, a transcriptional network dominated by fatty acid metabolism genes is linked to Ruminococcaceae (adjusted P < 0.05). Mucosal microbiota composition correlates with enrichment of intestinal epithelial cells, macrophages, and NK-cells. Overall, these data demonstrate the presence of context-specific mucosal host-microbe interactions in IBD, revealing significantly altered inflammation-associated gene-taxa modules, particularly in patients with fibrostenotic CD and patients using TNF-α-antagonists. This study provides compelling insights into host-microbe interactions that may guide microbiota-directed precision medicine and fuels the rationale for microbiota-targeted therapeutics as a strategy to alter disease course in IBD.

Limited predictive value of the gut microbiome and metabolome for response to biological therapy in inflammatory bowel disease.

Emerging evidence suggests the gut microbiome's potential in predicting response to biologic treatments in patients with inflammatory bowel disease (IBD). In this prospective study, we aimed to predict treatment response to vedolizumab and ustekinumab, integrating clinical data, gut microbiome profiles based on metagenomic sequencing, and untargeted fecal metabolomics. We aimed to identify predictive biomarkers and attempted to replicate microbiome-based signals from previous studies. We found that the predictive utility of the gut microbiome and fecal metabolites for treatment response was marginal compared to clinical features alone. Testing our identified microbial ratios in an external cohort reinforced the lack of predictive power of the microbiome. Additionally, we could not confirm previously published predictive signals observed in similar sized cohorts. Overall, these findings highlight the importance of external validation and larger sample sizes, to better understand the microbiome's impact on therapy outcomes in the setting of biologicals in IBD before potential clinical implementation.

Immune Checkpoint Inhibitor-related Pancreatitis: A Case Series, Review of the Literature and an Expert Opinion.

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of various malignancies, but are associated with serious adverse events like pancreatitis. Current guidelines are limited to the first step in treating acute ICI-related pancreatitis with steroids but lack treatment advices for steroid dependent pancreatitis. We describe a case series of 3 patients who developed ICI-related pancreatitis with chronic features such as exocrine insufficiency and pancreatic atrophy at imaging. Our first case developed after treatment with pembrolizumab. The pancreatitis responded well after discontinuation of immunotherapy but imaging showed pancreatic atrophy and exocrine pancreatic insufficiency persisted. Cases 2 and 3 developed after treatment with nivolumab. In both, pancreatitis responded well to steroids. However during steroid tapering, pancreatitis recurred and the latter developed exocrine pancreatic insufficiency and pancreatic atrophy at imaging. Our cases demonstrate resemblances with autoimmune pancreatitis based on clinical and imaging findings. In line, both diseases are T-cell mediated and for autoimmune pancreatitis azathioprine is considered as maintenance therapy. Guidelines of other T-cell mediated diseases like ICI-related hepatitis suggest tacrolimus. After adding tacrolimus in case 2 and azathioprine in case 3, steroids could be completely tapered and no new episodes of pancreatitis have occurred. These findings support the idea that the treatment modalities for other T-cell mediated diseases are worthwhile options for steroid dependent ICI-related pancreatitis.

Hepcidin and Iron Status in Patients With Inflammatory Bowel Disease Undergoing Induction Therapy With Vedolizumab or Infliximab.

BACKGROUND: Hepcidin, the systemic iron regulator, could be critical in differentiating iron deficiency (ID) from functional iron restriction in inflammatory bowel disease (IBD). We assessed hepcidin as a diagnostic ID marker and explored the relationship between hepcidin and its regulators in patients with IBD undergoing induction therapy with infliximab (IFX) or vedolizumab (VEDO). METHODS: Patients with active IBD receiving induction therapy with IFX or VEDO were included. Serum samples at baseline and after 6 weeks of induction therapy were analyzed for hepcidin, inflammation- and hypoxia-associated cytokines, and oxidative stress. Data were analyzed by stratifying based on the response at week 14. Results were compared with samples from age- and sex-matched healthy control subjects. RESULTS: Patients receiving induction therapy with IFX (n = 71) or VEDO (n = 51) and healthy control subjects (n = 50) were included. At baseline, hepcidin correlated positively with ferritin and negatively with soluble transferrin receptor/log ferritin index (P < .001). ID was prevalent in 96.7% of patients who had hepcidin levels below the median. Hepcidin accurately identified ID: the area under the curve (hepcidin) was 0.89 (95% confidence interval, 0.82-0.95; P < .001). In total, 75.4% of patients responded to induction therapy; inflammation, hepcidin, and ferritin decreased significantly, while transferrin increased during induction therapy. These changes were observed only in patients who responded to the therapy. CONCLUSIONS: Hepcidin levels in IBD are primarily determined by ID, even in an inflammatory state. In addition, induction therapy can decrease hepcidin levels, which might lead to better bioavailability of iron supplements. Therefore, hepcidin is a potential diagnostic ID biomarker that could assist therapeutic decision making.

Absolute iron deficiency is the primary determinant of hepcidin levels, even in an inflammatory state. Induction therapy can decrease hepcidin levels, which might improve iron bioavailability. Hence, hepcidin is a potential diagnostic iron deficiency biomarker that could assist therapeutic decision making.