ObjectivePatients 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.DesignStool 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.ResultsStrikingly, 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).ConclusionsWe 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.

The prevalence of GI complaints during and after running was low compared with that reported in other studies, which is partly due to the definition of "symptomatic" used in our study. The risk factors associated with becoming symptomatic were identical to those in other studies. The relationship between complaints during the run and the type of complaints afterwards suggests a role of GI ischaemia in the pathophysiology of running-induced GI symptoms.

Summary Background The prevalence of exercise‐induced gastrointestinal (GI) symptoms has been reported up to 70%. The pathophysiology largely remains unknown. Aim To review the physiological and pathophysiological changes of the GI‐tract during physical exercise and the management of the most common gastrointestinal symptoms. Methods Search of the literature published in the English and Dutch languages using the Pubmed database to review the literature that focused on the relation between splanchnic blood flow (SBF), development of ischaemia, postischaemic endotoxinemia and motility. Results During physical exercise, the increased activity of the sympathetic nervous system (SNS) redistributes blood flow from the splanchnic organs to the working muscles. With prolonged duration and/or intensity, the SBF may be decreased by 80% or more. Most studies point in the direction of increased SNS‐activity as central driving force for reduction in SBF. A severely reduced SBF may frequently cause GI ischaemia. GI‐ischaemia combined with reduced vagal activity probably triggers changes in GI‐motility and GI absorption derangements. GI‐symptoms during physical exercise may be prevented by lowering the exercise intensity, preventing dehydration and avoiding the ingestion of hypertonic fluids. Conclusions Literature on the pathophysiology of exercise‐induced GI‐symptoms is scarce. Increased sympathetic nervous system activity and decreased splanchnic blood flow during physical exercise seems to be the key factor in the pathogenesis of exercise‐induced GI‐symptoms, and this should be the target for symptom reduction.

Introduction: Blood C-reactive protein (CRP) and fecal calprotectin levels are routinely measured as surrogate markers of disease activity in Inflammatory Bowel Disease (IBD), but often do not correlate well with the degree of mucosal inflammation in the intestine as established by endoscopy. Therefore, novel predictive biomarkers are urgently needed that better reflect mucosal disease activity in IBD. The aim of this study was to identify a combination of serum inflammatory biomarkers predictive for endoscopic disease activity.Methods: Serum concentrations of 10 inflammatory biomarkers were analyzed in 118 IBD patients [64 Crohn's disease (CD), 54 ulcerative colitis (UC)] and 20 healthy controls. In a subset of 71 IBD patients, endoscopic disease activity was established. Non-parametric ROC estimation with bootstrap inference was used to establish the best combination of inflammatory biomarkers predicting endoscopic disease activity.Results: Six (6) inflammatory biomarkers (serum amyloid A (SAA), Eotaxin-1, IL-6, IL-8, IL-17A, and TNF-α) showed better prediction of IBD disease activity than routine measures (CRP, fecal calprotectin and HBI/SCCAI scores). The best combination of predictive inflammatory biomarkers consisted of serum SAA, IL-6, IL-8, and Eotaxin-1, showing an optimism-adjusted area under the ROC (AuROC) curve of 0.84 (95% CI: 0.73–0.94, P < 0.0001), which predicted significantly better (P = 0.002) than serum CRP levels with an AuROC of 0.57 (95% CI: 0.43–0.72, P = 0.32).Conclusion: The combination of SAA, IL-6, IL-8, and Eotaxin-1 reliably predicts endoscopic disease activity in IBD and might be valuable for monitoring disease activity and management of the disease.

Background Single-operator peroral cholangioscopy (sPOCS) is considered a valuable diagnostic modality for indeterminate biliary strictures. Nevertheless, studies show large variation in its characteristics and measures of diagnostic accuracy. Our aim was to estimate the diagnostic accuracy of sPOCS visual assessment and targeted biopsies for indeterminate biliary strictures. Additional aims were: estimation of the clinical impact of sPOCS and comparison of diagnostic accuracy with brush cytology. Methods A retrospective single-center study of adult patients who underwent sPOCS for indeterminate biliary strictures was performed. Diagnostic accuracy was defined as sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The clinical impact of sPOCS was assessed by review of medical records, and classified according to its influence on patient management. Results 80 patients were included, with 40 % having primary sclerosing cholangitis (PSC). Prior ERCP was performed in 88 %, with removal of a biliary stent prior to sPOCS in 55 %. The sensitivity, specificity, PPV, and NPV for sPOCS visual impression and targeted biopsies were 64 %, 62 %, 41 %, and 84 %, and 15 %, 65 %, 75 %, and 69 %, respectively. The clinical impact of sPOCS was limited; outcome changed management in 17 % of patients. Sequential brush cytology sensitivity, specificity, PPV, and NPV were 47 %, 95 %, 80 %, and 83 %. Conclusions The diagnostic accuracy of sPOCS for indeterminate biliary strictures was found to be inferior to brush cytology, with a low impact on patient management. These findings are obtained from a select patient population with a high prevalence of PSC and plastic stents in situ prior to sPOCS.

BackgroundSplanchnic artery stenosis is common and mostly asymptomatic and may lead to gastrointestinal ischemia (chronic splanchnic syndrome, CSS). This study was designed to assess risk factors for CSS in the medical history of patients with splanchnic artery stenosis and whether these risk factors can be used to identify patients with high and low risk of CSS.MethodsAll patients referred for suspected CSS underwent a standardized workup, including a medical history with questionnaire, duplex ultrasound, gastrointestinal tonometry, and angiography. Definitive diagnosis and treatment advice was made in a multidisciplinary team. Patients with confirmed CSS were compared with no-CSS patients.ResultsA total of 270 patients (102 M, 168 F; mean age, 53 years) with splanchnic artery stenosis were analyzed, of whom 109 (40%) had CSS and 161 no CSS. CSS-patients more often reported postprandial pain (87% vs. 72%, p = 0.007), weight loss (85% vs. 70%, p = 0.006), adapted eating pattern (90% vs. 79%, p = 0.005) and diarrhea (35% vs. 22%, p = 0.023). If none of these risk factors were present, the probability of CSS was 13%; if all were present, the probability was 60%. Adapted eating pattern (odds ratio (OR) 3.1; 95% confidence interval (CI) 1.08–8.88) and diarrhea (OR 2.6; 95% CI 1.31–5.3) were statistically significant in multivariate analysis.ConclusionsIn patients with splanchnic artery stenosis, the clinical history is of limited value for detection of CSS. A diagnostic test to detect ischemia is indispensable for proper selection of patients with splanchnic artery stenosis who might benefit from treatment.

GI ischaemia was present in all athletes during maximum intensity exercise and in 50% during submaximal exercise. Athletes with GI symptoms had higher gastric gradients per mmol/l increase in lactate, suggesting an increased susceptibility for the development of ischaemia during exercise. Treatment advice aimed at limiting GI ischaemia helped the majority of the referred athletes to reduce their complaints. Our results suggest an important role for GI ischaemia in the pathophysiology of their complaints.

Background Though a single nonmedical switch from the originator infliximab (IFX) to a biosimilar is considered effective and safe for most patients with inflammatory bowel disease (IBD), very limited data are available on multiple successive switches. Methods We performed a prospective multicenter cohort study of adult IBD patients who underwent 2 switches from the originator IFX to CT-P13 to SB2 (group 1), 1 switch from CT-P13 to SB2 (group 2), and 1 switch from the originator IFX to CT-P13 (group 3). Patients were assessed at 4 and 12 months since the most recent switch for remission using clinical (physician’s assessment) and biochemical (C-reactive protein [CRP], and fecal calprotectin [FC]) measures. Patients discontinuing treatment for ineffectiveness or adverse events before month 12 were imputed as nonremitters. Results One hundred seventy-six patients (Crohn’s disease 71%, ulcerative colitis 27.8%, IBD unclassified 1.2%; group 1, 69; group 2, 80; group 3, 27) were included. At 12 months after the most recent switch 76.9% (40 of 52, group 1), 65.7% (46 of 70, group 2) and 76.9% (20 of 26, group 3) of patients were in clinical remission. Treatment persistence at 12 months was 85.0%, 87.0%, and 70.1%, respectively. There were no significant differences in the rate of clinical, CRP, FC remission, or treatment persistence at 12 months between the 3 groups. Infusion reactions occurred in 1.7% of patients (3/176), all in patients with antidrug antibodies from group 2. Conclusions Multiple successive switching and switching between biosimilars of IFX seemed to be effective and safe.