Healthy First-degree Relatives Research Articles

Single-value brain activity scores reflect both severity and risk across the Alzheimer's continuum.

Single-value scores reflecting the deviation from (FADE score) or similarity with (SAME score) prototypical novelty-related and memory-related functional magnetic resonance imaging (fMRI) activation patterns in young adults have been proposed as imaging biomarkers of healthy neurocognitive aging. Here, we tested the utility of these scores as potential diagnostic and prognostic markers in Alzheimer's disease (AD) and risk states like mild cognitive impairment (MCI) or subjective cognitive decline (SCD). To this end, we analyzed subsequent memory fMRI data from individuals with SCD, MCI, and AD dementia as well as healthy controls (HC) and first-degree relatives of AD dementia patients (AD-rel) who participated in the multi-center DELCODE study (N = 468). Based on the individual participants' whole-brain fMRI novelty and subsequent memory responses, we calculated the FADE and SAME scores and assessed their association with AD risk stage, neuropsychological test scores, CSF amyloid positivity, and ApoE genotype. Memory-based FADE and SAME scores showed a considerably larger deviation from a reference sample of young adults in the MCI and AD dementia groups compared to HC, SCD and AD-rel. In addition, novelty-based scores significantly differed between the MCI and AD dementia groups. Across the entire sample, single-value scores correlated with neuropsychological test performance. The novelty-based SAME score further differed between Aβ-positive and Aβ-negative individuals in SCD and AD-rel, and between ApoE ε4 carriers and non-carriers in AD-rel. Hence, FADE and SAME scores are associated with both cognitive performance and individual risk factors for AD. Their potential utility as diagnostic and prognostic biomarkers warrants further exploration, particularly in individuals with SCD and healthy relatives of AD dementia patients.

Environmental Factors Associated with Risk of Crohn’s Disease Development in the CCC-GEM Project

To date, it is unclear how environmental factors influence Crohn's Disease (CD) risk and how they interact with biological processes. This study investigates the association between environmental exposures and CD risk and evaluates their association with pre-disease biomarkers. We studied 4,289 healthy first-degree relatives (FDRs) of CD patients from the Crohn's and Colitis Canada - Genetic, Environmental, Microbial (CCC-GEM) project. Regression models identified environmental factors associated with future CD onset and their association with pre-disease biological factors, including altered intestinal permeability measured by urinary fractional excretion of lactulose to mannitol ratio(LMR); gut inflammation via fecal calprotectin(FCP) levels; and fecal microbiome composition through 16S rRNA sequencing. Over a 5.62-year median follow-up, 86 FDRs developed CD. Living with a dog between ages 5-15 (HR=0.62; 95% CI=0.40-0.96; P = .034), and living with a large family size in the first year of life (HR=0.43; 95% CI=0.21-0.85; P = .016) were associated with decreased CD risk; whereas having a bird at the time of recruitment (HR=2.78; CI=1.36-5.68; P = .005) was associated with an increased CD risk. Furthermore, living with a dog was associated with reduced LMR, altered relative abundance of multiple bacterial genera, and increased Chao1 diversity; while bird owners had higher FCP levels. Large family during participants' first year of life was associated with altered microbiota composition without affecting FCP or LMR. This study identifies environmental variables associated with CD risk. These variables were also associated with altered barrier function, subclinical inflammation, and gut microbiome composition shifts, suggesting potential roles in CD pathogenesis.

A1 PRE-CLINICAL CROHN’S DISEASE MICROBIOME PROMOTES INFLAMMATION IN GNOTOBIOTIC RECIPIENT MICE

Abstract Background Crohn’s disease (CD) is a chronic disorder of unknow etiology. We recently demonstrated that microbiome composition is associated with the risk of CD development; however, its potential causal effect remains unknown. Aims Given the fact that first-degree relatives (FDRs) that are sibling likely to share similar environmental and genetic makeup, we selected pairs of discordant siblings (one remaining healthy referred to as healthy matched control-HMC, and the other who developed CD later on referred to as pre-CD) to investigate whether the microbiome contributes to or triggers dysregulated immune response by transplanting microbiome from them into germ-free mice (GFM). Methods Faecal samples from discordant siblings, recruited as part of the CCC-GEM project, a cohort of prospectively followed healthy first-degree relatives, were transplanted into RAG1-/- GFM before T-cell transfer-induced colitis. Fecal Lipocalin-2 (LCN-2) was measured by ELISA to assess gut inflammation. Body weight was monitored for 6 weeks after T-cell transfer. Intestinal tissue damage was assessed by histology scoring (PMID: 8623920). Pro-inflammatory cytokine gene profile of ileum and colon tissue was measured by qPCR. R-software was used for statistical analysis. Results Our results showed that mouse recipients of pre-CD microbiota experienced more weight loss than HMC group, with a greater difference observed in the second week after inducing colitis (p=0.0019). LCN-2 of pre-CD mice was significantly higher after T-cell transfer for 3 weeks. Intriguingly, pre-CD stool recipient mice had higher histological damage score in the ileum (p=0.025). Histological analysis revealed that granulomatous inflammation, mucin depletion, crypt loss were greater in pre-CD group (p≤0.05). Pre-CD stool promoted the expression of selected pro-inflammatory cytokine genes in the ileum with significant increases of TNFα, IL-1β, IFNγ, IL10 and TGFβ compared to mice that received HMC microbiome. Colonic tissue showed significant increases in TNFα and TGFβ in the mice recipient of the pre-CD microbiome. Conclusions These results suggests that pre-CD microbiome can worsen T cell transfer colitis in mice compared to HMC microbiome. This suggests that microbiome or other constituents of stool from pre-CD subjects are major contributors to the onset of disease. Modulating pre-CD microbiome composition could lead to novel methods to prevent CD onset. Funding Agencies CCC, CIHRWeston Family Foundation, Helmsley, Biocodex

A275 THE POTENTIAL MECHANISTIC ROLES OF SPHINGOLIPIDS IN HEALTHY FIRST-DEGREE RELATIVES OF PATIENTS WITH CROHN'S DISEASE

Abstract Background Crohn's Disease(CD) features a complex etiology intertwining genetic, environmental, and immunological dimensions. Sphingolipids (SPs) are pivotal lipid molecules within cell membranes and various biological processes, including cell growth, apoptosis, and inflammatory responses. While our prior research identified SPs as significant risk factors for CD onset, their pre-clinical influence on CD risk biomarkers and potential role in pathogenesis remains unclear Aims To identify the relationship between SPs and established CD risk factors Methods We used samples from healthy first-degree relatives(FDRs), followed in a nested case-control cohort from the Crohn's Colitis Canada- Genes, Environment, Microbial(GEM) project, matching those who developed CD(n=77) with control FDRs(n=303) based on age, sex, follow-up time, and geographic location. 59 SPs were selected from serum metabolites measured via an untargeted metabolomics platform. We used partial Spearman correlation to identify relationships between SPs and CD risk factors: i)intestinal permeability via the urinary fractional excretion ratio of lactulose to mannitol(LMR); ii)gut subclinical inflammation using fecal calprotectin(FCP); iii)systemic inflammation with C-reactive protein(CRP); iv)microbiome composition through fecal 16S rRNA sequencing and v)serum protein profile using the Olink® Proximity Extension Assay platform. A two-sided qampersand:003C0.05 was considered significant Results We identified 38 positive correlations between CRP and SPs across various sub-pathways, including Ceramides, Sphingomyelins and Hexosylceramides(0.117≤rho≤0.342, 1.37×10−09≤q≤0.042). One SP Ceramide(d18:1/16:0) correlated positively with FCP(rho=0.201, q=0.012). Moreover, two SPs, N-palmitoyl-sphingosine (d18:1/16:0) and glycosyl-N-(2-hydroxynervonoyl)-sphingosine (d18:1/24:1(2OH)), correlationed with Peptoclostridium genus (rho=0.465 and -0.245, q=1.47×10−16 and 0.028 respectively). All SPs correlated with one or more proteins, most positively between Sphingosine-1-phosphate and non-receptor tyrosine kinase(rho=0.637, q=1.98 ×10−36) and most negatively between sphingadienine and Chymotrypsin-C protein(rho=-0.334, q=4.11×10−8). No significant correlations emerged between SPs and LMR Conclusions We identified correlations between SPs and CD risk factors. The correlation with CRP suggests SPs might contribute to systemic inflammatory pathways related to CD. Moreover, correlations with the bacterial taxa highlight SPs' potential role in regulating microbial composition. Extensive correlations with proteins emphasize the pivotal impact of SPs on their function. This study may offer new insights into CD prevention Funding Agencies CCC, CIHR

A261 INVESTIGATING THE RELATIONSHIP BETWEEN AIR POLLUTION AND BIOMARKERS OF CROHN’S DISEASE IN CANADA

Abstract Background The cause of Crohn's disease (CD) remains unclear. Studies suggest a potential connection between CD and air pollution, with a higher occurrence of CD found in areas with higher pollution levels. Aims Our study sought to explore this potential connection by investigating the relationship between components of air pollution and biomarkers indicative of CD risk. Methods In total, 2,256 healthy first-degree relatives of patients with CD were recruited as part of the CCC-GEM Project. We assessed baseline samples of gut permeability using the urinary fractional excretion ratio of lactulose-to-mannitol (LMR), subclinical inflammation via fecal calprotectin (FCP), and stool microbiome using 16S-rRNA sequencing. Air pollutant (n=8) concentrations were obtained from the National Air Pollution Surveillance Database. We used postal code to estimate air pollutant exposure via inverse distance weighting, averaging data for one (pollutant1-month), three (pollutant3-months), and twelve months (pollutant12-months) prior to recruitment. We used generalized estimating equation models to find associations between pollutant exposure and LMR, FCP, and microbiome composition, adjusting for age, sex, air pollutant seasonality, familial income, and familial relationships. Significance was set at pampersand:003C0.05, and false discovery rate (q) correction was applied to microbiome analysis. Results We observed a negative association between particulate matter (PMµg/m3), PM101-month, and PM103-months and LMR (β=-0.06[-0.09, -0.01], p=6.0×10-3 and β=-0.05[-0.07, -0.01], p=7.6×10-4), and a positive association between PM103-months and FCP (β=0.05[0.001, 0.10], p=0.04). 12-month pollutant exposure was associated with seven microbial taxa in a logit model. Notably, Carbon monoxide (CO)12-months was associated with Oscillospiraceae UCG_003 (β=3.49[1.53, 5.46], q=0.03). PM2512-months was associated with Marvinbryantia (β=0.12[0.06, 0.18], q=0.02). PM1012-months was associated with Moryella (β=0.07[0.03, 0.10], q=0.02). Nitrogen dioxide (NO)12-months was associated with Coprobacter and Ruminococcaceae UBA1819 (β=0.05[0.02, 0.07], q=0.03 and β=0.05[0.02, 0.08], q=0.04). NOX12-months was also associated with Ruminococcaceae_UBA1819 as well as Intestinimonas (β=0.03[0.01, 0.04], q=0.04 and β=0.03[0.01, 0.04], q=0.02). Conclusions Air pollutant exposure was associated with biomarkers of gut inflammation, barrier function, and microbiome composition. A shorter exposure (1/3 months) primarily affected FCP and LMR, while longer-term exposure (12 months) exerted a discernible impact on the microbiome. These findings suggest that exposure to air pollution may modulate the gut barrier function, inflammation, and the gut microbiome, biomarkers that are associated with the development of CD. Funding Agencies Crohn’s and Colitis Canada Genetics Environment Microbial (CCC-GEM) III, Leona M. and Harry B. Helmsley Charitable Trust, Dr. Croitoru is the recipient of the Canada Research Chair in Inflammatory Bowel Diseases

Loss of symbiotic and increase of virulent bacteria through microbial networks in Lynch syndrome colon carcinogenesis.

Through a pilot study, we performed whole gut metagenomic analysis in 17 Lynch syndrome (LS) families, including colorectal cancer (CRC) patients and their healthy first-degree relatives. In a second asymptomatic LS cohort (n=150) undergoing colonoscopy-screening program, individuals with early precancerous lesions were compared to those with a normal colonoscopy. Since bacteria are organized into different networks within the microbiota, we compared related network structures in patients and controls. Fecal prokaryote DNA was extracted prior to colonoscopy for whole metagenome (n=34, pilot study) or 16s rRNA sequencing (validation study). We characterized bacteria taxonomy using Diamond/MEGAN6 and DADA2 pipelines and performed differential abundances using Shaman website. We constructed networks using SparCC inference tools and validated the construction's accuracy by performing qPCR on selected bacteria. Significant differences in bacterial communities in LS-CRC patients were identified, with an enrichment of virulent bacteria and a depletion of symbionts compared to their first-degree relatives. Bacteria taxa in LS asymptomatic individuals with colonic precancerous lesions (n=79) were significantly different compared to healthy individuals (n=71). The main bacterial network structures, constructed based on bacteria-bacteria correlations in CRC (pilot study) and in asymptomatic precancerous patients (validation-study), showed a different pattern than in controls. It was characterized by virulent/symbiotic co-exclusion in both studies and illustrated (validation study) by a higher Escherichia/Bifidobacterium ratio, as assessed by qPCR. Enhanced fecal virulent/symbiotic bacteria ratios influence bacterial network structures. As an early event in colon carcinogenesis, these ratios can be used to identify asymptomatic LS individual with a higher risk of CRC.

FIBER-DEFICIENT DIET INHIBITS COLITIS THROUGH REGULATION OF THE NICHE AND METABOLISM OF A GUT PATHOBIONT

Abstract Fiber free exclusive enteral nutrition (EEN) is an effective steroid-sparing treatment used to induce clinical remission in children with Crohn’s disease (CD). However, the mechanism underlying the beneficial effects of EEN remains obscure. We have generated a novel mouse strain that harbors mutations in two CD susceptibility genes (i.e, NOD2 and CYBB) and found that these mice spontaneously develop an early-onset (4 weeks of age), TH1-type gut inflammation, that closely recapitulates the human disease when exposed to a specific murine microbiota. Disease in Nod2/Cybb (DKO) mutants was triggered by a single mucus-dwelling anaerobe, Mucispirillum schaedleri, which markedly accumulates in the intestinal lumen and mucus layer prior to disease development. Given that our mouse model resembles early-onset CD, we have established a novel humanized mouse model of early-onset CD in which germ-free Nod2/Cybb mutants were colonized with microbiotas from early-onset-CD patients and their healthy first-degree relatives. We have found that the early-onset-CD-associated microbiota triggered intestinal inflammation in gnotobiotic DKO mice with all the hallmarks of the human disease. Using the murine and humanized models of early-onset CD we have found that administration of a fiber-free diet prevents the development of colitis and inhibits intestinal inflammation in colitic animals. Furthermore, identification of Mucispirillum as a trigger in our mouse model has allowed us to study the effects of dietary interventions on disease-causing microbes. Remarkably, we have found that a fiber-free diet alters the intestinal localization of Mucispirillum. Mechanistically, the absence of dietary fiber reduces the availability of nutrients and impairs Mucispirillum’s unique metabolic pathway in the intestinal mucus. Thus, appropriate localization of the pathobiont in the mucus layer is critical for the onset of disease, which can be disrupted by fiber exclusion. These results suggest that probing the intestinal niche and metabolism of disease-causing microbes will likely lead to the discovery of novel, more targeted therapies for the treatment of CD.

P321 Development and validation of an Integrated Risk Score for future risk of Crohn’s disease in healthy first-degree relatives: The CCC-GEM Project, a multicentre prospective cohort study

Abstract Background Although the cause of Crohn’s disease (CD) is unknown, recent studies have identified a number of biomarkers associated with the risk of developing CD in healthy at-risk individuals. Establishing a combined prediction model that stratifies the future risk of CD in healthy at-risk individuals is the first step towards disease prevention and a better understanding of the preclinical phase of CD. Methods We recruited healthy first-degree relatives (FDRs) of persons with CD from 2008-2017 as part of the global multicenter prospective Crohn’s and Colitis Canada Genetic Environmental Microbial (CCC-GEM) Project. After collecting demographic information, blood, urine, and stool samples at recruitment, participants were followed for the development of CD. A GEM-integrative risk score (GEM-IRS), using random survival forest modeling that combined the baseline variables (demographics, measures of gut inflammation – fecal calprotectin, intestinal barrier function – urinary fractional excretion ratio of lactulose to mannitol, and fecal microbiome composition and predicted functional capacities – based upon 16S rDNA sequencing and PICRUSt2) to estimate time-to-CD onset, was derived and subsequently validated in two independent testing cohorts. Results Among 2,619 FDRs followed for a median of 6.8 years, 61 (2.3%) developed CD. The GEM-IRS, developed on the training cohort (n= 1,170), upon validation, showed a c-statistic of 0.789 in the pooled-testing cohorts (0.786 in the North American Testing cohort (n=1,141) and 0.804 in the Israeli Cohort (n=308)). The 4th quartile group compared to the rest had significantly increased risk of CD (hazard ratio [HR] 6.42, 95% confidence interval [CI], 3.10-13.30) in the pooled-testing cohorts (HR 5.89, 95% CI, 2.70-12.85 in North American Testing cohort; HR 10.7, 95% CI 1.24-92.65 in Israeli cohort). Furthermore, the GEM-IRS predicted CD in pre-specified subgroups of FDRs with minimal subclinical inflammation (fecal calprotectin<50 ug/g) or normal barrier function measures (lactulose/mannitol ratio<0.025), and up to 7 years before diagnosis in the pooled-testing cohort. Conclusion The GEM-IRS, which includes biomarkers of gut inflammation, intestinal barrier function, and the gut microbiome, is a valid risk stratification tool for predicting future development of CD in healthy first-degree relatives of persons with CD. The score may be used to guide preventative care for healthy first-degree relatives.

P244 The first step to IBD prevention exploring rate of pre-clinical inflammation in subset of asymptomatic subjects at risk of IBD: screening stage of the PIONIR trial

Abstract Background With the increasing prevalence of inflammatory bowel diseases (IBD) globally, it is necessary to start focusing efforts on prevention of the diseases. The Genetic, Environmental, Microbial (GEM) study identified biological signatures predictive of developing IBD in first degree relatives (FDR) of patients with Crohn’s disease (CD). The ongoing PIONIR (Preventing IBD ONset in Individuals at Risk) study is a randomized controlled trial aimed to explore whether the Tasty & Healthy diet can change the CD-risk associated biomarkers of healthy FDRs who are particularly high risk of developing CD, originally followed in the GEM cohort. We report here the rate of IBD and pre-IBD inflammation in a subset cohort. Methods Subjects, 6-35 years of age from the GEM cohort who were identified by a combination of predictors at recruitment to GEM to have an increased risk for persistently elevated fecal calprotectin (FC) (i.e. Microbiome Risk Score (MRS), increased gut permeability and/or multiplex family of CD) were approached to perform a new FC test. Subjects who had FC>70µg/g, confirmed by a second sample, were offered a panenteric video capsule endoscopy (VCE), but some elected to proceed to ileocolonoscopy instead. Results For the PIONIR recruitment, a total of 450 subjects were approached from 7 sites in Israel and Canada, of whom 183 consented and provided a stool sample for FC (Figure). FC was elevated in 57 (31%) subjects, confirmed by re-testing in 36 (20%); 25/36 underwent VCE/ileocolonoscopy (Figure). In total, 8 (4.4% of the screened cohort) had normal-appearing mucosa, in 10 (5.5%) there were non-specific mucosal changes (e.g. several erosions or erythema), 6 (3.3%) had ulcers compatible with CD and 1 (0.6%) was inconclusive. The median FC of those eventually diagnosed with CD (816 [IQR 361-1123) was higher than the remaining 30 without IBD with elevated FC (175 [111-281], p=0.003). FC>275µg/g was highly predictive of CD in the entire cohort (AUROC 0.97 (95%CI 0.93-0.99); sensitivity 83%, specificity 94%). Conclusion Preclinical mucosal inflammation in VCE/ileocolonoscopy was found in 18 of 183 (9.8%) screened subjects (i.e. elevated FC with either normal or nonspecific mucosal findings), 134 (73%) had normal FC and 11 (6%) with elevated FC had missing VCE/ileocolonoscopy data. Six had CD (3.3%, or 17% of the 36 with elevated FC). Detecting subjects at risk at their preclinical stages, possibly with FC>275µg/g, is the first necessary step in developing preventive strategies for IBD.

Understanding Predictors of Crohn’s Disease: Determinants of Altered Barrier Function in Pre-Disease Phase of Crohn’s Disease

Abstract The pathogenesis of Crohn’s disease (CD) remains unknown. The current working theory is that genetic susceptibility influences host–microbe interactions, resulting in chronic inflammation. Case–control studies fail to explain the triggers or pathogenesis of the disease, notably due to confounding factors in patients with established disease. Investigating the pre-disease phase of CD improves the capacity to assess these confounding factors and enables us to identify biomarkers associated with increased risk of CD. The Crohn’s Colitis Canada-Genes, Environment, Microbial (CCC-GEM) project is a prospective cohort of healthy first-degree relatives of patients with CD, allowing us to interrogate the pre-disease phase of CD. The CCC-GEM Project has led to the identification of several demographic, serological, and microbiome composition markers associated with an increased risk of disease in pre-clinical participants. Notably, altered intestinal barrier function, as measured by the fractional urinary excretion of lactulose mannitol ratio, is associated with a significantly increased risk of CD. We review the intrinsic and external factors that are associated with altered intestinal barrier integrity, including genetic risk, subclinical inflammation, serum proteomics, intestinal microbiome composition, and environmental components, such as diet and lifestyle. Providing insights into the factors and mechanisms of altered barrier function contributes to our understanding of the pathogenic mechanisms of CD. These advances may aid in developing strategies for preventing disease in high-risk individuals. Further research and personalized strategies are needed to optimize these mitigation strategies for individuals at-risk for CD.

Gut microbial signatures of patients with primary hepatocellular carcinoma and their healthy first-degree relatives.

The gut microbiome has been recognized as a significant contributor to primary hepatocellular carcinoma (HCC), with mounting evidence indicating associations between bacterial components and cancers of the digestive system. Here, to characterize gut bacterial signature in patients with primary HCC and to assess the diagnostic potential of bacterial taxa for primary HCC, 21 HCC patients and 21 healthy first-degree relatives (control group) were enrolled in this study. Bacterial DNA in the fecal samples was quantified by 16S rRNA gene sequencing. We found that 743 operational taxonomic units (OTUs) were shared between patients with primary HCC and healthy controls. Of these, 197 OTUs were unique to patients with primary HCC, while 95 OTUs were unique to healthy subjects. Additionally, we observed significant differences in the abundance of Ruminococcaceae_UCG-014 and Romboutsia between patients with primary HCC and their healthy first-degree relatives. Besides, the relative abundance of Ruminococcaceae_UCG-014 and Prevotella_9 was positively correlated with physiological indicators including AST, ALT, ALB, or TBIL. Signature bacterial taxa could serve as non-invasive biomarkers, of which Romboutsia and Veillonella were identified as differential taxa in fecal samples from patients with HCC compared to healthy controls. Romboutsia showed a strong association with HCC (AUC=0.802). Additionally, the combination of Romboutsia and Veillonella (AUC=0.812) or the grouping of Fusobacterium, Faccalibacterium, and Peptostreptococcacae together (AUC=0.762) exhibited promising outcomes for the diagnosis of HCC. The composition of gut microbes in patients with HCC was found to be significantly altered. Differential taxa Romboutsia, Veillonella, and Peptostreptococcacae could be tested for identification of HCC.

Altered Heart Rate Variability During Rest in Schizophrenia: A State Marker.

Autonomic nervous system (ANS) imbalance has been reported in a number of psychiatric disorders such as depression, schizophrenia, panic disorder, etc. Autonomic dysfunction in schizophrenia has been associated with the symptoms and manifestation of psychosis. Heart rate variability (HRV) as a tool has been widely used to assess ANS activity and the effect of disease on the sympathovagal balance. Therefore, in the present study, HRV derived from electrocardiogram (ECG) lead II at rest was investigated in order to understand the changes in frequency domain measures in patients with schizophrenia and their first-degree relatives compared to healthy controls. Twenty-five patients with schizophrenia, 24 first-degree relatives of patients, and 24 healthy controls (Diagnostic and Statistical Manual of Mental Disorders (DSM)-5; 18-45 years) were included in the study. HRV of the subjects was measured after five minutes of rest. ECG lead II was recorded for five minutes and HRV was analysed in the frequency domain: low frequency (LF), high frequency (HF), total power, and LF/HF ratio. HRV parameters and heart rate were statistically analysed for group comparisons using general linear model multivariate analysis. Patients had significantly higher minimum heart rate and lower HF (normalized units (nu)) compared to their first-degree relatives. A trend was observed in HF (nu) with the lowest in patients followed by healthy controls and first-degree relatives and LF/HF ratio was the highest in patients followed by healthy controls and first-degree relatives, although not statistically significant. No significant difference was found between first-degree relatives and healthy controls. The alteration of HRV in schizophrenia could be attributed to reduction in vagal tone and sympathetic dominance, which in turn could serve as state markers of schizophrenia.

Dysregulation of adipokines levels among healthy first-degree relatives of type 2 diabetes patients

BackgroundLeptin, adiponectin and its ratio (L/A), as well as adipocyte fatty acid binding protein (A-FABP) have shown association to type 2 diabetes and atherosclerosis. Since first degree relatives (FDR) of type 2 diabetes are known to have higher risks of developing aforementioned diseases, this study aimed to see differences in adipokines profiles between FDR of type 2 diabetes and non-FDR counterpart. MethodsAge, sex and body mass index (BMI)-matched normotensive-normoglycemic subjects, aged 19–39 years with BMI<30 kg/m2, were included in this cross-sectional study. Serum adiponectin, leptin, and A-FABP levels were measured by sandwich ELISA while HOMA-IR was calculated from fasting blood glucose and insulin levels. ResultsOf 116 subjects recruited, there were significant difference of insulin level (6.00 vs 5.00 μIU/mL, P = 0.029) and HOMA-IR (1.27 vs 1.10, P = 0.028). Adiponectin, leptin, L/A ratio, and A-FABP levels were not statistically different between FDR and non-FDR groups. Stratified by BMI, non-obese FDR had higher L/A ratio (0.83 vs 0.49, P = 0.020) compared to those of corresponding non-FDR. In multivariate analysis, after adjusting for age, sex, waist circumference, BMI, and metabolic profiles (HbA1C, HOMA-IR, LDL-C, HDL-C, and triglyceride levels), FDR status became significantly associated with adiponectin level, and in non-obese subgroup, remained its significance with L/A ratio. ConclusionThe FDR status was independently associated with adiponectin level. Furthermore, higher L/A ratio was more pronounced in non-obese FDR than those of non-FDR subjects, suggesting that FDR status may already contribute to the development of adipokines dysregulation before obesity occurs.

Investigation of social cognition and cognitive impairment among patients with bipolar disorder, their healthy first-degree relatives, and the control group

Evidence regarding cognitive function in relatives of patients with bipolar disorder (BP) is controversial. This study aims to investigate social cognition and cognitive impairment among patients with BP, their healthy relatives (BP-Rel), and the healthy control group (HCs). A total of 180 participants in this study participated in three groups of 60 people, BP, BP-Rel, and HCs. All subjects were examined by the Bar-On emotional quotient inventory (Bar-On EQ-i), Gross Emotion Regulation Questionnaire (Gross -ERQ), and Screen for Cognitive Impairment in Psychiatry (SCIP) scale. In addition, the clinical and demographic data of the participants were also collected and analyzed by appropriate statistical methods (one-way analysis of variance, chi-square test, and correlation coefficient). Compared to BP-Rel and HCs, BP patients had lower overall emotional intelligence (EI) and emotion regulation (ER) scores. The overall scores of these sales were lower in BP-Rel compared to the control group. In addition, we also studied the correlation of the mentioned scales with SCIP subscales. Except for the working memory test and verbal fluency test, other SCIP subscales had a positive and significant correlation with the EI scale (p<.05). Regarding ER scale, all subscales of SCIP had a positive and significant correlation with the emotion regulation scale (p<.05). Healthy relatives of BP patients may also have maladaptive emotion regulation strategies. More studies are needed to confirm the above evidence on this issue.

Gut Microbiome Composition Is Associated With Future Onset of Crohn’s Disease in Healthy First-Degree Relatives

The cause of Crohn's disease (CD) is unknown, but the current hypothesis is that microbial or environmental factors induce gut inflammation in genetically susceptible individuals, leading to chronic intestinal inflammation. Case-control studies of patients with CD have cataloged alterations in the gut microbiome composition; however, these studies fail to distinguish whether the altered gut microbiome composition is associated with initiation of CD or is the result of inflammation or drug treatment. In this prospective cohort study, 3483 healthy first-degree relatives (FDRs) of patients with CD were recruited to identify the gut microbiome composition that precedes the onset of CD and to what extent this composition predicts the risk of developing CD. We applied a machine learning approach to the analysis of the gut microbiome composition (based on 16S ribosomal RNA sequencing) to define a microbial signature that associates with future development of CD. The performance of the model was assessed in an independent validation cohort. In the validation cohort, the microbiome risk score (MRS) model yielded a hazard ratio of 2.24 (95% confidence interval, 1.03-4.84; P= .04), using the median of the MRS from the discovery cohort as the threshold. The MRS demonstrated a temporal validity by capturing individuals that developed CD up to 5 years before disease onset (area under the curve > 0.65). The 5 most important taxa contributing to the MRS included Ruminococcus torques, Blautia, Colidextribacter, an uncultured genus-level group from Oscillospiraceae, and Roseburia. This study is the first to demonstrate that gut microbiome composition is associated with future onset of CD and suggests that gut microbiome is a contributor in the pathogenesis of CD.

The natural history study of preclinical genetic Creutzfeldt-Jakob Disease (CJD): a prospective longitudinal study protocol

BackgroundCreutzfeldt-Jakob Disease (CJD) is the most common prion disease in humans causing a rapidly progressive neurological decline and dementia and is invariably fatal. The familial forms (genetic CJD, gCJD) are caused by mutations in the PRNP gene encoding for the prion protein (PrP). In Israel, there is a large cluster of gCJD cases, carriers of an E200K mutation in the PRNP gene, and therefore the largest population of at-risk individuals in the world. The mutation is not necessarily sufficient for the formation and accumulation of the pathological prion protein (PrPsc), suggesting that other, genetic and non-genetic factors affect the age at symptoms onset. Here we present the protocol of a cross-sectional and longitudinal natural history study of gCJD patients and first-degree relatives of gCJD patients, aiming to identify biological markers of preclinical CJD and risk factors for phenoconversion.MethodsThe study has two groups: Patients diagnosed with gCJD, and first-degree healthy relatives (HR) (both carriers and non-carriers of the E200K mutation in the PRNP gene) of patients diagnosed with gCJD. At baseline, and at the end of every year, healthy participants are invited for an “in-depth” visit, which includes a clinical evaluation, blood and urine collection, gait assessment, brain MRI, lumbar puncture (LP), and Polysomnography (PSG). At 6 months from baseline, and then halfway through each year, participants are invited for a “brief” visit, which includes a clinical evaluation, short cognitive assessment, and blood and urine collection. gCJD patients will be invited for one “in-depth” visit, similar to the baseline visit of healthy relatives.DiscussionThis continuous follow-up of the participants and the frequent assessments will allow early identification and diagnosis in case of conversion into disease. The knowledge generated from this study is likely to advance the understanding of the underlying clinicopathological processes that occur at the very beginning of CJD, as well as potential genetic and environmental risk factors for the development of the disease, therefore advancing the development of safe and efficient interventions.Trial registrationThe study is an observational study. It has registered retrospectively in https://clinicaltrials.gov/ and has been assigned an identification number NCT05746715.

A198 THE LONG-TERM IMPACT OF ENVIRONMENTAL EXPOSURES ON HOST HEALTH AND THE RISK FACTORS OF CROHN'S DISEASE

Abstract Background Several environmental factors are associated with Crohn’s disease (CD) in large case-control studies; however, it is not clear how these factors maybe be influenced by age of exposure and if they are related to alterations in pre-disease biological markers of CD risk. Purpose To investigate the association between environmental factors in different age groups with future risk of CD onset and assess their relation to other pre-disease biomarkers. Method We used an environmental risk assessment questionnaire (ERA) to collect information from healthy first-degree relatives(FDR) of CD enrolled in the CCC-GEM project. ERA was a multi-item questionnaire querying 69 questions under 7 section headings: background, cultural/ethnic, smoking history, medical history, family history, environmental history and pet history. For the environmental and pet sections, current and historical (&amp;lt;1, 2-4, 5-15 years old) data was captured at the time of recruitment. We used Cox proportional hazard models to identify exposures associated with future CD onset. Next, we used regression models to identify the relationship of exposures with biological factors associated with CD risk previously identified by our group i.e.: i) intestinal permeability using urinary fractional excretion of lactulose to mannitol ratio (LMR) with LMR≥0.025 defined as abnormal; ii) subclinical inflammation using fecal calprotectin (FCP) with FCP≥100µg/g; and iii) fecal microbiome composition and diversity using 16S rDNA sequencing. Two-sided p&amp;lt;0.05 (or false discovery rate corrected p&amp;lt;0.05) were considered significant. Result(s) A total of 4289 FDRs were recruited, 47% were male, median recruitment age was 17.0 years[6-35]. After a median follow-up of 5.6-years (IQR=3.42-8.67), 86 FDRs developed CD. Living with a dog between age 5-15 (Hazard Ratio (HR)=0.61; 95% confidence interval (CI)=0.39-0.95), and a large family size (&amp;gt;3) in the first year of life (HR=0.41; 95% CI=0.22-0.89) were protective against CD onset. Conversely, having a bird at time of survey (HR=2.84; CI=1.37-5.90), and having a sibling with CD (HR=2.07; 95% CI=1.18-3.63) were risk factors for CD onset. We found that owning a dog between age of 5-15 (Odd Ratio(OR)=0.77, 95% CI=0.65-0.90) was significantly associated with LMR, nine taxa bacterial and higher chao1 diversity index. Having a bird at time of survey was significantly associated with FCP (OR=2.04, 95% CI=1.33-3.11). There was no association between large family size and having a CD sibling with gut microbiome, FCP or LMR. Conclusion(s) The study identified four environmental factors associated with future development of CD. Among them, exposure to dogs during early life was protective against CD onset and might be explained by its association with normal gut permeability and microbiome. We also identified that having a bird at recruitment increased risk of CD onset which might be mediated by an increase in subclinical inflammation. Submitted on behalf of the CCC-GEM consortium Disclosure of Interest None Declared

A238 BILE ACID COMPOSITION AND DIETARY FAT: IMPLICATIONS FOR CROHN’S DISEASE IN A COHORT OF HEALTHY FIRST-DEGREE RELATIVES

Abstract Background Crohn’s disease (CD) is a chronic relapsing inflammatory disease of the gastrointestinal tract. The etiology of CD may arise from complex interactions including host genetics, diet, and the intestinal microbiome. Increased consumption of saturated fats, characteristic of the Western diet, is a known risk factor for CD. Dietary fat (DF) is absorbed by the host through the release of primary bile acids (PBAs) and bio-transformed by the microbiome into secondary bile acids (SBAs). Altogether, bile acids (BAs) can act as signaling molecules involved in host immune regulation and potentially in CD onset. Purpose To investigate the relationship between CD risk, BAs, and DF, and evaluate the predictive performance of CD onset of these factors by developing machine learning models. Method We used samples healthy first-degree relatives (FDRs) recruited as part of the Crohn’s Colitis Canada- Genes, Environment, Microbial (GEM) project. Those who developed CD (n=87) were matched 1:4 by age, sex, follow-up time, and geographic location with control FDRs remaining healthy (n=347). Serum, urine, and stool BA were measured using ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy. DF types were derived from food frequency questionnaire data. We used conditional logistic regressions to identify associations between CD onset, BAs (n=93), and DFs (n=9). We further explored the relationships of significant CD-related BAs and DF via Generalized Estimation Equations. Finally, we used a tree-based machine-learning algorithm (XGBoost) with 5-fold cross-validation to assess the prediction performance of CD onset using BA from all sources as well as DF. Two-sided p&amp;lt;0.05 was considered significant. Result(s) In total, 10 of 93 BAs, and two of nine DFs were significantly associated with increased odds of CD onset (p&amp;lt;0.05). Additionally, five BAs were significantly associated with DF (p&amp;lt;0.05). Serum-derived BAs had the best predictive performance for CD, with a mean AUC of 0.70 [95% CI: 0.63;0.76], followed by stool derived BAs with a mean AUC= 0.65 [0.55;0.75], and followed by urine derived Bas with a mean AUC= 0.57 [0.48;0.66]. Lastly DF was not a predictive marker of CD onset with a mean AUC= 0.50 [0.41;0.60]. Conclusion(s) This study suggests that BAs are associated with the pathogenesis of CD and the effects may be influenced by DF. Serum-derived BAs may be able to better predict the risk of CD than other stool or urine derived BA, while DF is not directly implicated in CD risk. Submitted on behalf of the CCC-GEM consortium. Funding Crohn’s and Colitis Canada Genetics Environment Microbial (CCC-GEM) III The Leona M. and Harry B. Helmsley Charitable Trust Kenneth Croitoru is the recipient of the Canada Research Chair in Inflammatory Bowel Diseases The International Organization for the Study of Inflammatory Bowel Diseases (IOIBD) Jingcheng Shao is the recipient of a Data Science Institute Summer Undergraduate Data Science award Disclosure of Interest None Declared

A218 ASSOCIATIONS BETWEEN ADHERENCE TO LITERATURE-DERIVED DIETARY INDICES AND PRE-DISEASE BIOMARKERS: IMPLICATIONS FOR CROHN’S DISEASE PREVENTION

Abstract Background The incidence of Crohn’s disease (CD) is increasing globally, indicating a significant environmental influence such as diet. A plethora of dietary adherence (DA) patterns exist in the literature: the Mediterranean Diet (MD), Empirical Dietary Inflammatory Pattern (EDIP), Specific Carbohydrate Diet (SCD), and low Fermentable Oligosaccharide, Disaccharide, Monosaccharide, or Polyol diet (FODMAP) are all potential candidates to maintain a reduced level of inflammation, improving gastrointestinal function. Contrary, the Westernized diet (WD) is generally reported as a diet promoting inflammation in humans. Purpose To determine if DA to literature-derived dietary indices in a cohort of first-degree relatives (FDRs) of CD patients can modulate pre-disease biomarkers. Method We used food frequency questionnaire (FFQ) data from 2,696 healthy FDR subjects of the Crohn’s Colitis Canada- Genes, Environment, Microbial (CCC-GEM) project. We rederived each of the following scores using our FFQ data, utilizing originally described methods for the MD, EDIP, SCD, low FODMAP, and WD to obtain DA. Each diet was correlated pairwise via Kendall’s Tau. We fit multivariable regression models to identify the association of DA (top quintile vs remaining) and: i) intestinal permeability using urinary fractional excretion of lactulose to mannitol ratio (LMR), LMR≥0.03 defined abnormal; ii) subclinical inflammation using fecal calprotectin (FCP) measured with BÜHLMANN fCAL® ELISA, FCP≥250µg/g defined inflammation; and iii) fecal microbiome richness and composition using 16S rRNA sequencing. Two-sided p&amp;lt;0.05 for primary and q&amp;lt;0.05 for secondary analysis defined significance. Result(s) There were positive correlations between the MD, SCD, and low FODMAP, these diets negatively correlated with the WD. The EDIP negatively correlated with the SCD and low FODMAP, did not correlate with the MD, and positively correlated with the WD. No diet was associated with abnormal LMR or FCP. Only the SCD was associated with increased microbial richness (q=0.03). All diets were associated with microbial genera: the MD (n=18 taxa, (2.0-7&amp;lt;q-values&amp;lt; 0.04), EDIP (n=9, [2.8-4-0.05]), SCD (n=13, [3.7-11-0.05]), low FODMAP (n=14, [1.3-7-0.05]), and WD (n=1, [0.03]). Conclusion(s) This study shows that literature-derived dietary indices correlate generally with each other, yet none were not associated with abnormal LMR or FCP. However, we found that diet can impact microbiome richness and composition. Thus, it is tempting to speculate that diet is a possible intervention capable of maintain microbiome homeostasis to reduce future risk of CD. Submitted on behalf of the CCC-GEM consortium. Funding Crohn’s and Colitis Canada Genetics Environment Microbial (CCC-GEM) III The Leona M. and Harry B. Helmsley Charitable Trust Kenneth Croitoru is the recipient of the Canada Research Chair in Inflammatory Bowel Disease Disclosure of Interest None Declared

A39 HEALTHY FIRST-DEGREE RELATIVES FROM MULTIPLEX FAMILIES VERSUS SIMPLEX HARBOR A HIGHER RISK OF DEVELOPING CROHN'S DISEASE AND ARE ASSOCIATED WITH SUBCLINICAL INFLAMMATION AND ALTERED MICROBIOME COMPOSITION

Abstract Background Healthy individuals within families with multiple affected members (multiplex families) with Crohn’s disease (CD) have a notably high risk of developing CD. No large prospective pre-disease cohort has assessed differences in preclinical intestinal inflammation, permeability, fecal microbiome, and genetics in healthy at-risk subjects from multiplex families. Purpose We aimed to assess differences in subclinical gut inflammation, genetic risk, gut barrier function, and fecal microbiota composition between first-degree relatives (FDRs) from families with 2 or more affected members (multiplex) and families with only one affected member (simplex). Also, we aimed to assess the risk of future CD onset in subjects from multiplex versus simplex families. Method We utilized the GEM Project cohort of healthy FDRs of CD patients. Subclinical gut inflammation was assessed using fecal calprotectin (FCP) at recruitment. Gut barrier function was assessed using the lactulose-to-mannitol ratio (LMR). For assessment of the CD-related genetic risk, CD-polygenic risk scores (CD-PRS) were calculated. Microbiome composition was assessed by sequencing fecal 16S ribosomal RNA. Generalized estimating equations logistic regression and LEfSe (PMID: 21702898) were used to assess the associations between multiplex status and different outcomes. A Cox proportional hazards model was used to assess time-related risk of future onset of CD. Result(s) 4385 subjects were included. Median age was 17 [IQR 12-24] years, 52.9% were female, 69.4% were siblings and 30.6% were offspring. 4052 (92.4%) and 333 (7.6 %) were simplex and multiplex subjects, respectively. After adjusting for age, sex, family size, and relation to proband, multiplex status was significantly associated with higher baseline FCP (p=0.038), but was not associated with either baseline LMR or CD-PRS (p=0.19 and p=0.33, respectively). We found no significant differences in alpha diversity (Shannon index) (p=0.57) between simplex and multiplex subjects. Beta diversity analysis assessed by the Bray-Curtis dissimilarity index did not reveal significant differences (R2=3e-04, p=0.607). The genera Eisenbergiella, Eggerthellaceae uncultured, and Morganella, were significantly more abundant in multiplex subjects, whereas Lachnospira, Sutterella, Lachnospiraceae_NK4A136_group, and Lachnospiraceae_UCG_004 less abundant. The risk of CD onset was significantly higher in multiplex subjects. In multivariable analysis, multiplex status at recruitment was associated with increased risk of CD onset (adjusted HR 3.41, 95% CI 1.70-6.87, p=0.00055), after adjusting for demographics, FCP, LMR, and CD-PRS. Conclusion(s) Multiplex status compared to simplex is associated with a 3.4-fold increased risk of CD onset, a higher FCP, and fecal bacterial composition. A comprehensive assessment of environmental factors that increase CD risk in multiplex families remains to be elucidated in future studies. Disclosure of Interest None Declared