Association of diet and outdoor time with inflammatory bowel disease: a multicenter case-control study using propensity matching analysis in China.

Objective: To investigate the association between dietary and some other environmental factors and the risk of inflammatory bowel diseases (IBD) in Chinese population. Materials and methods: A multicenter case-control study was conducted involving 11 hospitals across China. A total of 1,230 subjects were enrolled consecutively, and diet and environmental factor questionnaires were collected. IBD patients were matched with healthy controls (HC) using propensity-score matching (PSM) at a 1:1 ratio with a caliper value of 0.02. Multivariate conditional logistic regression analyses were performed to evaluate the associations between diet, environmental factors, and IBD. Results: Moderate alcohol and milk consumption, as well as daily intake of fresh fruit, were protective factors for both Crohn's disease (CD) and ulcerative colitis (UC). Conversely, the consumption of eggs and chocolate increased the risk of IBD. Outdoor time for more than 25% of the day was a protective factor only for CD. In eastern regions of China, CD patients had higher egg consumption and less outdoor time, while UC patients consumed more chocolate. IBD patients from urban areas or with higher per capita monthly income consumed more fruit, eggs, and chocolate. Conclusions: This study reveals an association between specific foods, outdoor time, and the emergence of IBD in the Chinese population. The findings emphasize the importance of a balanced diet, sufficient outdoor time and activities, and tailored prevention strategies considering regional variations.

Vitamin D and CRP are associated in hospitalized inflammatory bowel disease (IBD) patients in Shanghai.

BACKGROUND AND OBJECTIVES: Patients with inflammatory bowel disease (IBD) are more likely to be confirmed with vitamin D deficiency. However, the association between inflammation and vitamin D remains unclear. The purpose of this study was to evaluate the association between inflammation and vitamin D in hospitalized patients with IBD. METHODS AND STUDY DESIGN: All the participants were recruited from one teaching hospital from June 2018 to October 2022. Inflammation was evaluated by serum concentration of C-reactive protein (CRP), using an immunoturbidimetric method at admission. We further divided the participants into five groups based on serum CRP levels: <5, 5-9.9, 10-19.9, 20-39.9, and >40mg/L. Serum 25-hydroxy-vitamin D (25-(OH)-D) was assessed by liquid chromatography tandem mass spectrometry. Addi-tional information, including age, sex, body mass index (BMI), IBD (ulcerative colitis vs. Crohn's disease) subtype, was abstracted from medical records. RESULTS: This study included 1,989 patients with IBD (average age was 39.4 years, 33.8% of them were women, 1,365 CD and 624 UC patients). The median CRP was 5.49 mg/L (range of quartiles: 1.64~19.5 mg/L) and the prevalence of 25-(OH)-D deficiency was 69.8%. CRP was significantly associated with serum level of 25-(OH)-D. The difference in 25-(OH)-D was -4.28 ng/ml (-5.27 ng/ml, -3.31 ng/ml) between two extremist CRP groups after adjustment of potential covariates (age, sex, BMI, type of IBD, dietary type, season, and lymphocyte count). Subgroup analysis in sex, type of IBD, and age, were similar to the main analysis results. CONCLUSIONS: There was a negative association between CRP levels and vitamin D in hospitalized patients with IBD.

Association of selected adipokines with vitamin D deficiency in children with inflammatory bowel disease.

BACKGROUND: Adipose tissue is significantly involved in inflammatory bowel disease (IBD). Vitamin D can affect both adipogenesis and inflammation. The aim of this study was to compare the production of selected adipokines, potentially involved in the pathogenesis of IBD - adiponectin, resistin, retinol binding protein 4 (RBP-4), adipocyte fatty acid binding protein and nesfatin-1 in children with IBD according to the presence of 25-hydroxyvitamin D (25(OH)D) deficiency. METHODS: The study was conducted as a case-control study in pediatric patients with IBD and healthy children of the same sex and age. In addition to adipokines and 25(OH)D, anthropometric parameters, markers of inflammation and disease activity were assessed in all participants. RESULTS: Children with IBD had significantly higher resistin levels regardless of 25(OH)D levels. IBD patients with 25(OH)D deficiency only had significantly lower RBP-4 compared to healthy controls and also compared to IBD patients without 25(OH)D deficiency. No other significant differences in adipokines were found in children with IBD with or without 25(OH)D deficiency. 25(OH)D levels in IBD patients corelated with RBP-4 only, and did not correlate with other adipokines. CONCLUSIONS: Whether the lower RBP-4 levels in the 25(OH)D-deficient group of IBD patients directly reflect vitamin D deficiency remains uncertain. The production of other adipokines does not appear to be directly related to vitamin D deficiency.

Association between tunneled catheter placement and catheter-associated deep venous thrombosis in adults with inflammatory bowel disease receiving home parenteral nutrition: A retrospective cohort study.

BACKGROUND: Patients with inflammatory bowel disease (IBD) are at increased risk of thrombosis. They often need parenteral nutrition (PN) requiring intravenous access for prolonged periods. We assessed the risk of deep vein thrombosis (DVT) associated with peripherally inserted central catheters (PICCs) and tunneled catheters for patients with IBD receiving home PN (HPN). METHODS: Using the Cleveland Clinic HPN Registry, we retrospectively studied a cohort of adults with IBD who received HPN between June 30, 2019 and January 1, 2023. We collected demographics, catheter type, and catheter-associated DVT (CADVT) data. We performed descriptive statistics and Poisson tests to compare CADVT rates among parameters of interest. We generated Kaplan-Meier graphs to illustrate longevity of CADVT-free survival and a Cox proportional hazard model to calculate the hazard ratio associated with CADVT. RESULTS: We collected data on 407 patients, of which, 276 (68%) received tunneled catheters and 131 (32%) received PICCs as their initial catheter. There were 17 CADVTs with an overall rate of 0.08 per 1000 catheter days, whereas individual rates of DVT for PICCs and tunneled catheters were 0.16 and 0.05 per 1000 catheter days, respectively (P = 0.03). After adjusting for age, sex, and comorbidity, CADVT risk was significantly higher for PICCs compared with tunneled catheters, with an adjusted hazard ratio of 2.962 (95% CI=1.140-7.698; P = 0.025) and adjusted incidence rate ratio of 3.66 (95% CI=2.637-4.696; P = 0.013). CONCLUSION: Our study shows that CADVT risk is nearly three times higher with PICCs compared with tunneled catheters. We recommend tunneled catheter placement for patients with IBD who require HPN infusion greater than 30 days.

Taxonomic and phenotypic analysis of bifidobacteria isolated from IBD patients as potential probiotic strains.

BACKGROUND: Inflammatory Bowel Diseases (IBD) are a major public health issue with unclear aetiology. Changes in the composition and functionality of the intestinal microbiota are associated with these pathologies, including the depletion of strict anaerobes such as Feacalibacterium prausnitzii. Less evidence is observed for depletion in other anaerobes, among which bifidobacteria. This study characterized the taxonomic and functional diversity of bifidobacteria isolated from the human intestinal microbiota in active and non-active IBD patients by a culturomics approach and evaluated if these bifidobacteria might be used as probiotics for gut health. RESULTS: A total of 341 bifidobacteria were isolated from the intestinal microbiota of IBD patients (52 Crohn's disease and 26 ulcerative colitis patients), with a high proportion of Bifidobacterium dentium strains (28% of isolated bifidobacteria). In ulcerative colitis, the major species identified was B. dentium (39% of isolated bifidobacteria), in active and non-active ulcerative colitis. In Crohn's disease, B. adolescentis was the major species isolated from non-active patients (40%), while similar amounts of B. dentium and B. adolescentis were found in active Crohn's disease patients. The relative abundance of B. dentium was increased with age, both in Crohn's disease and ulcerative colitis and active and non-active IBD patients. Antibacterial capacities of bifidobacteria isolated from non-active ulcerative colitis against Escherichia coli LF82 and Salmonella enterica ATCC 14028 were observed more often compared to strains isolated from active ulcerative colitis. Finally, B. longum were retained as strains with the highest probiotic potential as they were the major strains presenting exopolysaccharide synthesis, antibacterial activity, and anti-inflammatory capacities. Antimicrobial activity and EPS synthesis were further correlated to the presence of antimicrobial and EPS gene clusters by in silico analysis. CONCLUSIONS: Different bifidobacterial taxonomic profiles were identified in the microbiota of IBD patients. The most abundant species were B. dentium, mainly associated to the microbiota of ulcerative colitis patients and B. adolescentis, in the intestinal microbiota of Crohn's disease patients. Additionally, the relative abundance of B. dentium significantly increased with age. Furthermore, this study evidenced that bifidobacteria with probiotic potential (antipathogenic activity, exopolysaccharide production and anti-inflammatory activity), especially B. longum strains, can be isolated from the intestinal microbiota of both active and non-active Crohn's disease and ulcerative colitis patients.

Recent Immigrants With Inflammatory Bowel Disease Have Significant Healthcare Utilization From Preconception to Postpartum: A Population Cohort Study.

INTRODUCTION: Immigrants with inflammatory bowel disease (IBD) may have increased healthcare utilization during pregnancy compared with non-immigrants, although this remains to be confirmed. We aimed to characterize this between these groups. METHODS: We accessed administrative databases to identify women (aged 18-55 years) with IBD with a singleton pregnancy between 2003 and 2018. Immigration status was defined as recent (<5 years of the date of conception), remote (≥5 years since the date of conception), and none. Differences in ambulatory, emergency department, hospitalization, endoscopic, and prenatal visits during 12 months preconception, pregnancy, and 12 months postpartum were characterized. Region of immigration origin was ascertained. Multivariable negative binomial regression was performed for adjusted incidence rate ratios (aIRRs) with 95% confidence intervals (CIs). RESULTS: A total of 8,880 pregnancies were included, 8,304 in non-immigrants, 96 in recent immigrants, 480 in remote immigrants. Compared with non-immigrants, recent immigrants had the highest rates of IBD-specific ambulatory visits during preconception (aIRR 3.06, 95% CI 1.93-4.85), pregnancy (aIRR 2.15, 95% CI 1.35-3.42), and postpartum (aIRR 2.21, 1.37-3.57) and the highest rates of endoscopy visits during preconception (aIRR 2.69, 95% CI 1.64-4.41) and postpartum (aIRR 2.01, 95% CI 1.09-3.70). There were no differences in emergency department and hospitalization visits between groups, although those arriving from the Americas were the most likely to be hospitalized for any reason. All immigrants with IBD were less likely to have a first trimester prenatal visit. DISCUSSION: Recent immigrants were more likely to have IBD-specific ambulatory care but less likely to receive adequate prenatal care during pregnancy.

Histopathology imaging and clinical data including remission status in pediatric inflammatory bowel disease.

The incidence of inflammatory bowel disease (IBD) is increasing annually. Children with IBD often suffer significant morbidity due to physical and emotional effects of the disease and treatment. Corticosteroids, often a component of therapy, carry undesirable side effects with long term use. Steroid-free remission has become a standard for care-quality improvement. Anticipating therapeutic outcomes is difficult, with treatments often leveraged in a trial-and-error fashion. Artificial intelligence (AI) has demonstrated success in medical imaging classification tasks. Predicting patients who will attain remission will help inform treatment decisions. The provided dataset comprises 951 tissue section scans (167 whole-slides) obtained from 18 pediatric IBD patients. Patient level structured data include IBD diagnosis, 12- and 52-week steroid use and name, and remission status. Each slide is labelled with biopsy site and normal or abnormal classification per the surgical pathology report. Each tissue section scan from an abnormal slide is further classified by an experienced pathologist. Researchers utilizing this dataset may select from the provided outcomes or add labels and annotations from their own institutions.

Ca2+-Dependent Processes of Innate Immunity in IBD.

IBD is an uncontrolled inflammatory condition of the gastrointestinal tract, which mainly manifests in two forms: ulcerative colitis (UC) and Crohn's disease (CD). The pathogenesis of IBD appears to be associated with an abnormal response of innate and adaptive immune cells. Innate immunity cells, such as macrophages, mast cells, and granulocytes, can produce proinflammatory (e.g., TNF-α) and oxidative stress (ROS) mediators promoting intestinal damage, and their abnormal responses can induce an imbalance in adaptive immunity, leading to the production of inflammatory cytokines that increase innate immune damage, abate intestinal barrier functions, and aggravate inflammation. Considering that Ca2+ signalling plays a key role in a plethora of cellular functions, this review has the purpose of deepening the potential Ca2+ involvement in IBD pathogenesis.

Orally administrated liquid metal agents for inflammation-targeted alleviation of inflammatory bowel diseases.

Rapid drug clearance and off-target effects of therapeutic drugs can induce low bioavailability and systemic side effects and gravely restrict the therapeutic effects of inflammatory bowel diseases (IBDs). Here, we propose an amplifying targeting strategy based on orally administered gallium (Ga)-based liquid metal (LM) nano-agents to efficiently eliminate reactive oxygen and nitrogen species (RONS) and modulate the dysregulated microbiome for remission of IBDs. Taking advantage of the favorable adhesive activity and coordination ability of polyphenol structure, epigallocatechin gallate (EGCG) is applied to encapsulate LM to construct the formulations (LM-EGCG). After adhering to the inflamed tissue, EGCG not only eliminates RONS but also captures the dissociated Ga to form EGCG-Ga complexes for enhancive accumulation. The detained composites protect the intestinal barrier and modulate gut microbiota for restoring the disordered enteral microenvironment, thereby relieving IBDs. Unexpectedly, LM-EGCG markedly decreases the Escherichia_Shigella populations while augmenting the abundance of Akkermansia and Bifidobacterium, resulting in favorable therapeutic effects against the dextran sulfate sodium-induced colitis.

Body-wide genetic deficiency of poly(ADP-ribose) polymerase 14 sensitizes mice to colitis.

Inflammatory bowel disease (IBD) is a chronic disease of the gastrointestinal tract affecting millions of people. Here, we investigated the expression and functions of poly(ADP-ribose) polymerase 14 (Parp14), an important regulatory protein in immune cells, with an IBD patient cohort as well as two mouse colitis models, that is, IBD-mimicking oral dextran sulfate sodium (DSS) exposure and oral Salmonella infection. Parp14 was expressed in the human colon by cells in the lamina propria, but, in particular, by the epithelial cells with a granular staining pattern in the cytosol. The same expression pattern was evidenced in both mouse models. Parp14-deficiency caused increased rectal bleeding as well as stronger epithelial erosion, Goblet cell loss, and immune cell infiltration in DSS-exposed mice. The absence of Parp14 did not affect the mouse colon bacterial microbiota. Also, the colon leukocyte populations of Parp14-deficient mice were normal. In contrast, bulk tissue RNA-Seq demonstrated that the colon transcriptomes of Parp14-deficient mice were dominated by abnormalities in inflammation and infection responses both prior and after the DSS exposure. Overall, the data indicate that Parp14 has an important role in the maintenance of colon epithelial barrier integrity. The prognostic and predictive biomarker potential of Parp14 in IBD merits further investigation.

Ribonuclease 4 functions as an intestinal antimicrobial protein to maintain gut microbiota and metabolite homeostasis.

Antimicrobial proteins contribute to host-microbiota interactions and are associated with inflammatory bowel disease (IBD), but our understanding on antimicrobial protein diversity and functions remains incomplete. Ribonuclease 4 (Rnase4) is a potential antimicrobial protein with no known function in the intestines. Here we find that RNASE4 is expressed in intestinal epithelial cells (IEC) including Paneth and goblet cells, and is detectable in human and mouse stool. Results from Rnase4-deficient mice and recombinant protein suggest that Rnase4 kills Parasutterella to modulate intestinal microbiome, thereby enhancing indoleamine-2,3-dioxygenase 1 (IDO1) expression and subsequently kynurenic and xanthurenic acid production in IECs to reduce colitis susceptibility. Furthermore, deceased RNASE4 levels are observed in the intestinal tissues and stool from patients with IBD, correlating with increased stool Parasutterella. Our results thus implicate Rnase4 as an intestinal antimicrobial protein regulating gut microbiota and metabolite homeostasis, and as a potential diagnostic biomarker and therapeutic target for IBD.

Non-destructive diagnosis of Inflammatory Bowel Disease by near-infrared spectroscopy and aquaphotomics.

Inflammatory Bowel Disease includes Crohn's Disease and Ulcerative Colitis. Currently, diagnosing involves a series of current diagnostic methods that are invasive, time-consuming, and expensive. Near-infrared spectroscopy and aquaphotomics can detect changes in biofluids and thus have the potential to diagnose disease. This study aimed to investigate the diagnostic ability of near infrared spectroscopy and aquaphotomics for Inflammatory Bowel Disease and its types. This method used blood plasma and saliva samples absorbance spectrum and multivariate analysis with the Principal Component Analysis and, Linear Discriminant Analysis, Quadratic Discriminant Analysis, and Support Vector Machine in the range 1300-1600 nm and 12 water absorbance bands in this range, separately. In the near-infrared range, total accuracy of 100% led to the separation of the healthy group and Inflammatory Bowel Disease and then the separation of the healthy group and patients with Ulcerative Colitis and Crohn's Disease. The aquaphotomics approach was used to investigate the changes in the 12 water absorbance bands and their impact on the accuracy of the diagnostic method. Aquaphotomics also detected 100% of the mentioned samples. We achieved a fast, accurate, non-invasive method based on near-infrared spectroscopy and aquaphotomics to diagnose Inflammatory Bowel Disease and its types using blood plasma or saliva samples. The current study found that monitoring blood plasma or saliva using near-infrared spectra offers an opportunity to thoroughly investigate biofluids and changes in their water spectral patterns caused by complex physiological changes due to Inflammatory Bowel Disease and its types, and to visualize these changes using aquagram.

Helicobacter Pylori infection in children with inflammatory bowel disease: a prospective multicenter study.

BACKGROUND: The relationship between Helicobacter-pylori(Hp)infection and inflammatory-bowel-disease(IBD) in pediatric-patients remains controversial. We aimed to assess the Hp-infection occurrence in newly-diagnosed pediatric-patients with IBD compared to no-IBD patients. Additionally, we aimed to examine differences in clinical-activity-index(CAI) and endoscopic-severity-score(ESS)between IBD-patients with and without Hp-infection, at baseline and at 1-year-follow-up(FU), after eradication-therapy(ET). METHODS: IBD diagnosis was based on Porto-criteria, and all patients underwent gastroscopy at baseline and 1-year FU. For Crohn's-disease(CD) and ulcerative colitis(UC), IBD-CAI and -ESS were classified using PCDAI/SES-CD and PUCAI/UCEIS, respectively. RESULTS: 76 IBD-patients were included in the study[35 F(46.1%),median-age 12(range 2-17)]. CD and UC were diagnosed in 29(38.2%) and 45(59.2%)patients, respectively, and unclassified-IBD in two(2.6%)patients. Non-IBD patients were 148[71 F(48.0%),median-age 12(range 1-17)]. Hp-infection at baseline was reported in 7(9.2%) and 18(12.2%)IBD and non-IBD patients, respectively(p = 0.5065). The 7 IBD patients with Hp infection were compared to 69 IBD patients without Hp-infection at baseline evaluation, and no significant differences were reported considering CAI and ESS in these two groups. At 1-year FU, after ET, IBD patients with Hp infection improved, both for CAI and ESS, but statistical significance was not reached. CONCLUSION: The occurrence of Hp-infection did not differ between IBD and no-IBD patients. No differences in CAI or ESS were observed at the diagnosis, and after ET no worsening of CAI or ESS was noted at one-year FU, between Hp-positive and -negative IBD patients.

Abnormal platelet parameters in inflammatory bowel disease: a systematic review and meta-analysis.

BACKGROUND: Platelet dysfunction plays a critical role in the pathogenesis of inflammatory bowel disease (IBD). Despite clinical observations indicating abnormalities in platelet parameters among IBD patients, inconsistencies persist, and these parameters lack standardization for diagnosis or clinical assessment. METHODS: A comprehensive search was conducted in the PubMed, Embase, Web of Science, and Cochrane Library databases for relevant articles published up to December 16th, 2023. A random-effects model was employed to pool the weighted mean difference (WMD) and 95% confidence interval (95% CI) of platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT) between IBD patients and healthy controls, and subgroup analyses were performed. RESULTS: The meta-analysis included 79 articles with 8,350 IBD patients and 13,181 healthy individuals. The results revealed significantly increased PLT and PCT levels (WMD: 69.910, 95% CI: 62.177, 77.643 109/L; WMD: 0.046%, 95% CI: 0.031%, 0.061%), and decreased MPV levels (WMD: -0.912, 95% CI: -1.086, -0.739 fL) in IBD patients compared to healthy individuals. No significant difference was found in PDW between the IBD and control groups (WMD: -0.207%, 95% CI: -0.655%, 0.241%). Subgroup analysis by disease type and disease activity showed no change in the differences for PLT, PCT, and MPV in the ulcerative colitis and Crohn's disease groups, as well as the active and inactive groups. Notably, the active group exhibited significantly lower PDW levels than the control group (WMD: -1.138%, 95% CI: -1.535%, -0.741%). CONCLUSIONS: Compared with healthy individuals, IBD patients display significantly higher PLT and PCT and significantly lower MPV. Monitoring the clinical manifestations of platelet abnormalities serves as a valuable means to obtain diagnostic and prognostic information. Conversely, proactive measures should be taken to prevent the consequences of platelet abnormalities in individuals with IBD. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42023493848.

Serum calgranulin C as a non-invasive predictor of activity among inflammatory bowel disease.

Inflammatory bowel disease is a chronic immune-mediated disorder with a relapsing and remitting course. It leads to disabling gastrointestinal symptoms, low quality of life, and a significant burden for healthcare utilization and associated costs. Therefore, non-invasive biomarkers are needed for early diagnosis and follow up to avoid the complications of invasive diagnostic procedures. Calgranulin C is a calcium binding protein with proinflammatory properties. The aim of this study was to evaluate the role of serum calgranulin C as a non-invasive biomarker for diagnosis and prediction of activity in comparison to different biomarkers and endoscopic activity scores in inflammatory bowel disease. The study included 80 inflammatory bowel disease patients (50 Ulcerative colitis and 30 Chron's patients) and 20 normal controls. Complete blood picture, C-reactive protein, erythrocyte sedimentation rate, fecal calprotectin and serum calgranulin C were measured. Colonoscopies with histopathological examination were done and different activity scoring systems assessed. Among ulcerative colitis group, serum calgranulin C was statistically significantly higher in comparison to control group [723.640±529.055 ng/ml versus 80.850±24.416 ng/ml]. Depending on the American college of gastroenterology ulcerative colitis activity index, fecal calprotectin and serum calgranulin C were statistically significantly higher among moderate to severe ulcerative colitis than those with mild activity and those in remission (p < 0.001, for both). Regarding Crohn's disease group, serum calgranulin C was statistically significantly higher in comparison to control group [759.233±797.963 ng/ml versus 80.850±24.416 ng/mL]. Depending on Crohn's disease activity index, both serum calgranulin C and fecal calprotectin were statistically significantly higher among active disease than those in remission (p < 0.001, for both). In conclusion, serum calgranulin C could be used as a non-invasive marker to predict activity and severity and to ensure remission among inflammatory bowel disease patients.

Integrating plasma proteomics with genome-wide association data to identify novel drug targets for inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic disease that includes Crohn's disease (CD) and ulcerative colitis (UC). Although genome-wide association studies (GWASs) have identified many relevant genetic risk loci, the impact of these loci on protein abundance and their potential utility as clinical therapeutic targets remain uncertain. Therefore, this study aimed to investigate the pathogenesis of IBD and identify effective therapeutic targets through a comprehensive and integrated analysis. We systematically integrated GWAS data related to IBD, UC and CD (N = 25,305) by the study of de Lange KM with the human blood proteome (N = 7213) by the Atherosclerosis Risk in Communities (ARIC) study. Proteome-wide association study (PWAS), mendelian randomisation (MR) and Bayesian colocalisation analysis were used to identify proteins contributing to the risk of IBD. Integrative analysis revealed that genetic variations in IBD, UC and CD affected the abundance of five (ERAP2, RIPK2, TALDO1, CADM2 and RHOC), three (VSIR, HGFAC and CADM2) and two (MST1 and FLRT3) cis-regulated plasma proteins, respectively (P < 0.05). Among the proteins identified via Bayesian colocalisation analysis, CADM2 was found to be an important common protein between IBD and UC. A drug and five druggable target genes were identified from DGIdb after Bayesian colocalisation analysis. Our study's findings from genetic and proteomic approaches have identified compelling proteins that may serve as important leads for future functional studies and potential drug targets for IBD (UC and CD).

Causality of genetically determined blood metabolites on inflammatory bowel disease: a two-sample Mendelian randomization study.

Inflammatory bowel disease (IBD) is a chronic and recurrent inflammatory disease of the gastrointestinal tract, including two subtypes: Crohn's disease (CD) and ulcerative colitis (UC). Metabolic disorders are important factors in the development of IBD. However, the evidence for the causal relationship between blood metabolites and IBD remains limited. A two-sample MR analysis was applied to evaluate relationships between 486 blood metabolites and IBD. The inverse variance weighted method was chosen as the primary MR analysis method. False discovery rate correction was used to control for false positives in multiple testing. Following complementary and sensitivity analyses were conducted using methods such as weight median, MR-egger, weighted mode, simple mode, Cochran Q test, and MR-PRESSO. Moreover, we performed replication, meta-analysis, Steiger test, and linkage disequilibrium score regression to enhance the robustness of the results. Additionally, we performed metabolic pathway analysis to identify potential metabolic pathways. As a result, we identified four significant causal associations between four blood metabolites and two IBD subtypes. Specifically, one metabolite was identified as being associated with the development of CD (mannose: odds ratio (OR) = 0.19, 95% confidence interval (CI) 0.08-0.43, P = 8.54 × 10-5). Three metabolites were identified as being associated with the development of UC (arachidonate (20:4n6): OR = 0.18, 95% CI 0.11-0.30, P = 2.09 × 10-11; 1, 5-anhydroglucitol: OR = 2.21, 95% CI 1.47-3.34, P = 1.50 × 10-4; 2-stearoylglycerophosphocholine: OR = 2.66, 95% CI 1.53-4.63, P = 5.30 × 10-4). The findings of our study suggested that the identified metabolites and metabolic pathways can be considered as useful circulating metabolic biomarkers for the screening and prevention of IBD in clinical practice, as well as candidate molecules for future mechanism exploration and drug target selection.