bluuebunny/crossref_metadata_2025 huggingface dataset:
P0060 GPR15L counteracts chronic colitis by shaping the intestinal microbiota
Authors: Leggio M , Schramm S , Ocón B , Wirtz S , Puertolas Balint F , Dietz L , Schröder B , Butcher E , Müller T , Neurath M F , Zundler S
Published: January 2025

Background

The G protein-coupled receptor 15 (GPR15) is expressed on gut-homing T cells and the interaction of the GPR15 ligand GPR15L with GPR15 has recently been shown to crucially control integrin-dependent adhesion to the endothelium. However, the impact of GPR15L, which is predominantly expressed by colonic epithelial cells, on experimental colitis and inflammatory bowel disease (IBD) is currently not clear.

Methods

We studied GPR15L in experimental colitis with Gpr15l-deficient and -overexpressing mice as well as with rectal application of recombinant GPR15L. We performed phenotypical and molecular disease characterization using endoscopy, IVIS in vivo imaging, histology, immunofluorescence, FISH, qPCR, and multiplex ELISA. We also performed bulk RNA and metagenomic sequencing. We analyzed the expression of GPR15L in samples from IBD patients and non-IBD controls using qPCR and immunofluorescence and correlated it with clinical information. We explored the function of GPR15L in vitro using radial diffusion assays and antimicrobial assays.

Results

Acute DSS colitis was aggravated in Gpr15l-deficient mice compared to Gpr15l-proficient mice, while it was attenuated in Gpr15l-transgenic mice. This was T cell-independent, since the phenotype was conserved in Rag-/-Gpr15l-/- mice. Moreover, it was independent of Gpr15 in T cell transfer colitis with Gpr15-deficient and -proficient donor cells. RNA sequencing of colon tissue from Gpr15l-/- and Gpr15l+/+ mice with DSS colitis showed differential regulation in genes related to mucosal barrier function and host-microbiota crosstalk. Accordingly, 16S rRNA sequencing revealed a substantial difference in the intestinal microbial diversity of Gpr15l-/- and Gpr15l+/+ mice. Shotgun metagenomics and radial diffusion assays revealed that GPR15L acts as a selective anti-microbial peptide on community and single strain level, respectively, that predominantly restrains the growth of pathogenic bacteria. Rectal supplementation of recombinant GPR15L in Gpr15l-/- mice rescued increased disease severity in acute DSS colitis and reduced bacterial abundance and translocation. Patients with IBD showed reduced expression of GPR15L compared to controls. Furthermore, the expression of GPR15L was lower in patients with high disease severity compared to those with low severity. Finally, flare-free survival in patients with high GPR15L expression was substantially longer than in patients with low GPR15L expression.

Conclusion

GPR15L counteracts experimental colitis and seems beneficial in human IBD. Mechanically, it acts as an anti-microbial peptide to promote the homeostasis of the intestinal microbiota. Thus, GPR15L emerges as a potential future therapeutic approach for IBD.
P0064 Investigating a pathogenic role for IL-18 in Inflammatory Bowel Disease beyond the classical type 1 immunity paradigm
Authors: Grillmaier M , Barendregt D , Calado B , Heredia M , Smits W , Tuk B , van Berkel L , Hulleman-van Haaften D , Klomberg R , Vuijk S , Camman A , Doukas M , de Ridder L , Escher J , Samsom J
Published: January 2025

Background

Crohn’s disease (CD) and ulcerative colitis (UC) are intestinal diseases driven by chronic reactivation of memory T helper (Thm) 1-like and Th17m cells, respectively. Disease remission remains difficult to achieve and maintain due to inter-patient heterogeneity in disease severity and underlying immune responses. Moreover, variations in the pathogenic Thm responses, the treatment target, are understudied. The proinflammatory cytokine IL-18 enhances IL-12-induced IFN-γ production by Th1 cells, as seen in Th1-driven inflammatory diseases. However, its potential pathogenic role in immune-mediated diseases, like CD and UC, is unclear. Upon investigating immune responses in therapy-naïve pediatric CD and UC patients, we detected increased IL-18 plasma concentrations that were correctable by therapy. We hypothesized that IL-18 plays a role in both CD and UC by stimulating Th1m but also Th17m cells, worsening disease.

Methods

We examined therapy-naïve pediatric CD and UC patient plasma proteomics (92 proteins, Proximity Extension Assay technology; CD: n=85, UC: n =31, control: n=25), circulating gut-homing Thm populations, transcriptomes of intestinal biopsies (CD: n=57, UC: n =21, control: n=12), and clinical disease parameters. Further, we assessed cytokine responses by healthy donor-derived Th1m and Th17m cells after IL-18 and IL-12 stimulation in vitro.

Results

Plasma IL-18 concentrations correlated to concentrations of Th1-associated proteins (IFN-γ, CXCL9, CXCL11, CXCL10, PDL1) in CD and UC. Interestingly, in UC patients, IL-18 concentrations also correlated to Th17-associated proteins (IL-12B, IL-17A, IL-24). In agreement, preliminary in vitro data showed that IL-18 + IL-12 stimulation increases IL-17A- and IFN-γ-secreting cell frequencies in CCR6+ Th17m cells. In CD, plasma IL-18 concentrations correlated to frequencies of circulating gut-homing CCR6+CXCR3+CCR4+ Th17m, a pathogenic population known to acquire Th1 features and IFN-γ production. Ileal and colonic mRNA expression of IL-18 pathway genes associated with degree of histological inflammation. Higher IL-18 plasma concentrations at diagnosis associated with moderate to severe disease and worse endoscopic scores in both CD and UC and greater disease extent in UC, suggesting a relationship between IL-18 and disease severity. In line with its preferential production in the ileum, plasma IL-18 concentrations were significantly higher in CD patients with ileal involvement compared to CD patients with colonic disease.

Conclusion

We identify IL-18 as a potential enhancer of both Th1-like and Th17-driven inflammation. High plasma IL-18 is detectable in subgroups of CD and UC patients, raising the question whether IL-18 acts on a specific disease-associated Thm cell population.
P0070 Distinct Serum Proteome Alterations Following Vedolizumab and Ustekinumab Therapy in IBD Patients
Authors: Saliutina M , Cancino C , Juhran K S , Fritz K , Eleftheriadou A M , Velasco Blazquez L , Konopka A , Luo Y , Weidinger C , Sonnenberg E , Siegmund B , Hegazy A N ,   Charité IBD Group
Published: January 2025

Background

Inflammatory bowel disease (IBD) is a chronic intestinal disorder characterized by relapse and remission. Dysregulated cytokine networks and excessive immune activation drive intestinal inflammation. Therapies targeting cytokines (e.g., TNF, IL-12/23) and immune cell trafficking (e.g., integrin inhibitors) have been effective. However, the impact of anti-integrin (vedolizumab) and anti-IL-12/23 (ustekinumab) therapies on systemic inflammation is poorly understood. This study compares serum proteome profiles of patients treated with vedolizumab or ustekinumab to elucidate their distinct effects on inflammatory pathways.

Methods

This study included patients with Crohn’s disease (CD), ulcerative colitis (UC), and age- and sex-matched healthy donors (HD), who received either ustekinumab or vedolizumab treatment. The ustekinumab cohort comprised 23 CD and 10 UC patients, while the vedolizumab cohort included 7 CD and 27 UC patients. Serum samples were collected from ustekinumab-treated patients at baseline (week 0) and 8 weeks post-treatment, and from vedolizumab-treated patients at baseline (week 0) and 6 weeks post-treatment. Additionally, serum samples were collected from 32 healthy donors. Proteomic analysis was performed using the Olink Inflammation Panel, measuring 92 inflammation-related proteins. Differential protein expression analysis was conducted to compare baseline and post-treatment samples within each cohort.

Results

Serum proteomic analysis using the Olink Inflammation panel revealed significant alterations in the levels of 15 proteins in IBD patients compared to healthy controls. Pro-inflammatory markers, including 4E-BP1, SIRT2 and TNF were significantly upregulated, indicating immune activation in IBD. Conversely, anti-inflammatory regulators, such as LIF-R and SCF, were significantly downregulated. Ustekinumab treatment led to upregulation of IL-12B and downregulation of 4E-BP1, SIRT2. Notably, IL-12B was upregulated in both CD and UC, while 4E-BP1 and SIRT2 were downregulated in CD (week 8 vs week 0). Conversely, vedolizumab treatment induced robust proteomic changes over time. Between week 0 and week 6, majority of proteins showed significant differential expression, more than the differences observed between IBD and HD groups.

Conclusion

Serum proteomic profiles of IBD patients differ from healthy donors. Ustekinumab induced minimal serum changes, indicating a limited systemic effect, while vedolizumab led to substantial proteomic shifts, suggesting broader modulation of inflammation. These distinct effects highlight the differing mechanisms of ustekinumab and vedolizumab on systemic inflammation in IBD, prompting further investigation to optimize therapeutic strategies.
P0071 Host fecal proteolytic activity is increased following antibiotic treatment in healthy individuals, but not patients with pouchitis
Authors: Werner L , Nissenbaum T , Izhar R , Hirsch A , Fibelman M , Leibovitzh H , Cohen N , Lobel L , Maharshak N
Published: January 2025

Background

Antibiotics (Abx) are crucial for treating infections but significantly disrupt the gut microbiome. While fecal metagenomic studies explored microbial taxa affected by Abx, metaproteomic analyses are lacking. This study investigates how Abx treatment influences host and bacterial activities in healthy individuals and in patients with pouch inflammation (pouchitis).

Methods

We conducted label-free quantitative LC-MS/MS analyses on stool samples from 7 controls and 6 patients with pouchitis, before and after Abx treatment.

Proteins were identified using the unified human gut proteome database. Proteolytic activity was measured in fecal extracts, using a fluorescence kit. Statistical analyses were performed using MSstats in R. p-value<0.05 and Log2fold-change>1 were considered significant after adjustment for multiple comparisons.

Results

Principal component analysis showed that metaproteomes clustered according to disease state and Abx treatment. Before Abx, there was distinct expression of host immune proteins and proteases; as well as of hundreds of microbial proteins, when comparing patients with pouchitis to controls.

In healthy individuals, Abx treatment resulted in diminished protein abundance, (e.g., MUC12) and enrichment of several proteases (CELA2A and CTRC). Concurrently, hundreds of microbial proteins were not expressed after Abx. Pouchitis proteins expression was less affected by Abx, possibly due to a pre-existing dysbiosis.

Comparison of healthy and pouchitis metaproteomes post-Abx treatment revealed enrichment in immunoglobulins and immune proteins (REG1) among pouchitis patients. Conversely, healthy show enrichment in host proteases (CELA3A, TMPRSS15) and serine protease inhibitors. Microbial proteins were also enriched in healthy compared to patients with pouchitis after Abx, though the effect was less pronounced than in pre-Abx samples.

Last, measurements of proteolytic activity in stool extracts, demonstrated that Abx treatment increased proteolytic activity in healthy individuals to levels resembling patients with pouchitis at baseline and post-Abx. Intriguingly, patients with pouchitis showed no further increase in proteolytic activity after Abx treatment.

Conclusion

Proteolytic activity is increased following Abx treatment in healthy individuals, opposed to patients with pouchitis, who exhibit increased proteolytic activity at baseline and post-Abx. The finding that microbial proteins were enriched in healthy compared to pouchitis, before and after Abx, underscores the importance of the microbiome for the homeostasis of the luminal proteolytic activity. Further research is needed to understand how microbial dysbiosis enriches host protease abundance.
P0076 A novel CXCR7 agonist inhibits the intestinal inflammation in Dextran sulfate sodium(DSS)-induced colitis animal model
Authors: Kim Y , Lee Y S , Eun Hee C
Published: January 2025

Background

Inflammatory Bowel Disease (IBD), comprising Ulcerative Colitis (UC) and Crohn's Disease (CD), is a chronic inflammatory disorder characterized by dysregulated immune responses. Chemokines, which play crucial roles in immune regulation, have been implicated in the pathogenesis of IBD. However, the specific function of CXCR7 in IBD pathology remains largely unexplored. In this study, we investigated the therapeutic potential of our newly developed CXCR7 agonist in a preclinical IBD animal model.

Methods

Female C57BL/6J mice were divided into normal, model vehicle, 2 doses of IL21120033 (30, 60 mg/kg), and a positive control group (Cyclosporine A), each with 8-10 mice. Colitis was induced by 2% DSS administration in drinking water for 6 days followed by regular water for 3 days. Vehicle or test compound were administered orally once daily from Day 0-9. The disease activity index (DAI) was measured every day. Following the 9-day treatment period, animals were euthanized and colons were harvested for gross anatomical measurements. Longitudinally bisected colon specimens were either fixed for histopathological evaluation or cryopreserved at -80°c for subsequent IL-6 gene expression analysis.

Results

IL21120033 treatment significantly reduced DAI by 25% and 39% at 30 and 60 mg/kg, respectively. Both colon weight and length showed significant improvement compared to the model vehicle group. Histopathological analysis revealed decreased inflammation scores in IL21120033-treated groups. IL-6 mRNA expression demonstrated dose-dependent reduction following IL21120033 treatment.

Conclusion

IL21120033 demonstrated significant therapeutic efficacy in DSS-induced colitis, representing the first CXCR7 agonist showing beneficial effects in IBD. These findings suggest CXCR7 as a potential therapeutic target for IBD treatment.
P0077 Identification of symbiote candidates for pouchitis in patients with ulcerative colitis
Authors: Uchino M , Son A , Kato T , Nakanishi Y , Hanawa S , Matsuo Y , Ogura H , Ohno H , Ishido S , Nomura K , Tomoo Y , Kusunoki K , Horio Y , Kuwahara R , Ikeuchi H
Published: January 2025

Background

Ulcerative colitis (UC) has been recognized as a life-long inflammatory disease. Although several novel treatments for UC has been developed, medication-uncontrollable UC patients require the surgical treatment. The surgical operation could improve the quality of life of the patients, but requires intensive medical following, because more than 40% develop to pouchitis. We have explored the symbiote candidates for Ileoanal pouch through comprehensive microbiome and metabolome analysis to prove the mechanism of pouchitis.

Methods

The fecal samples in patients with or without pouchitis were collected. 16S rRNA amplicon meta-analysis and metabolome analysis for 170 patients were performed.

Results

The alfa diversity in microbiome was significantly decreased with developing pouchitis. Several bacterial genera which include Lachnospiraceae, Bifidobacteriaceae, Prevotellaceae, Clostridiaceae, Ruminococcaceae, and Veillonellaceae were statistically reduced in correlation with inflammatory clinical score and were shown having significant relation with protective metabolites. In addition, the extent of decrease in these candidates was strikingly prominent in medication-refractory pouchitis. Additionally, some pouchitis revealed the increasing of Enterobacteriaceae, unclassified Lactobacillas, or Propionibacteriaceae.

Conclusion

Thus, our data show these bacterial taxa as symbiote candidates and could be attractive targets for maintenance of Ileal pouch in UC.
P0090 Synergistic reduction of inflammatory cytokines with obefazimod and etrasimod in combination treatment vs. either monotherapy in a mouse model of inflammatory bowel disease
Authors: Garcel A , Cataldi F , Scherrer D
Published: January 2025

Background

Obefazimod (Obe) is an investigational, oral, once-daily small molecule that enhances expression of microRNA-124 and has shown both efficacy and safety in Phase 2 studies in patients with moderately to severely active ulcerative colitis (UC) [1, 2]. Due to a therapeutic ceiling of 10-20% placebo adjusted remission rates among available monotherapy strategies, combination therapies are gaining interest as a treatment strategy [3]. We present early preclinical data on the combination of Obe and the sphingosine-1-phosphate receptor modulator etrasimod (Etra) in a mouse model of inflammatory bowel disease.

Methods

The efficacy of Obe and Etra, as monotherapies and in combination, in preventing colitis was assessed using the mouse T-cell adoptive transfer (TCT) model. CD4+CD45high T-cells from immunocompetent C57BI/6J mice were transferred into RAG2 knockout mice.

Treatments were administered daily (10 ml/kg, p.o.) from Day 0 (1h before cell transfer) until Day 55: vehicle (0.5% methylcellulose), Obe (40 or 100 mg/kg, Obe40, Obe100), Etra (3 mg/kg), Obe40 + Etra, Obe100 + Etra.

Body weight (BW), disease activity index (DAI, based on BW loss, fecal consistency, and fecal blood), and levels of inflammatory cytokines in the colon and blood were measured to assess disease severity and inflammation.

Results

Obe40 alone did not protect against BW loss and colitis (as measured by DAI), while Etra alone prevented BW loss but did not fully prevent colitis. Instead, the combination Obe40 + Etra improved BW and the response on DAI. Obe100 alone protected against BW loss and colitis. The combination Obe100 + Etra did not improve BW and DAI compared to Obe100 alone.

At day 55, in the colon tissue, Obe100 induced a statistically significant decrease in TNFα, IL-17 and IFNγ, while Etra did not. The combination of Obe100 + Etra increased the reduction of these cytokines in the colon.

At day 55, in the blood, Obe100 induced a statistically significant reduction in IL-17 levels, while Etra induced a significant decrease in TNFα levels. The combination therapy induced a synergistic reduction of TNFα, IL-17, IL-6 and IFNγ.

Conclusion: In the mouse TCT model, the combination of Obe and Etra improved BW and DAI and reduced CD4+ cell numbers and inflammatory cytokines in both colon and blood, showing a synergistic reduction of cytokine levels in the blood. These promising findings suggest that this combination could provide enhanced therapeutic potential for treating inflammatory conditions like UC.

References

1. Vermeire S, et al. J Crohns Colitis 2023

2. Vermeire S, et al. The Lancet Gastroenterol & Hepatol 2022

3. Solitano V, et al. Gastroenterol & Hepatol 2023.
P0096 Impaired fatty acid oxidation is a hallmark of Ulcerative Colitis: evidence from multi-cohort transcriptomics analysis
Authors: Piernik M , Eder P
Published: January 2025

Background

Ulcerative colitis (UC) is characterized by persistent colonic mucosal inflammation. Despite available treatments, most patients experience only temporary remission. The lack of universally effective treatments results from our incomplete understanding of UC pathophysiology. While many gene expression studies have provided valuable insights into UC mechanisms, the growing availability of transcriptomics datasets offers a unique opportunity for large-scale, cross-validating analyses. Here, we used multiple independent datasets to identify the most consistently dysregulated pathways in UC mucosal biopsies.

Methods

We performed an integrative analysis of 10 open transcriptomics datasets from human UC and healthy mucosal biopsies (n=710 samples after selection). Each dataset underwent a separate differential expression analysis followed by gene set enrichment. We used 6 different gene set databases to make the analysis as broad as possible (9962 pathways). The results were aggregated across all datasets to identify consistently altered genes and pathways. Since each dataset has a different number of samples and a different sample distribution between the groups, the aggregation was done purely on the ranking level. The complete workflow of the experiment is in Figure 1.

Results

Mitochondrial fatty acid oxidation emerged as the most significantly dysregulated pathway with a mean rank 4 (median 2.5) across 6 datasets. The analysis revealed a coordinated pattern of metabolic rewiring: systematic downregulation of the entire mitochondrial transport machinery (CPT1A, SLC25A20, CPT2) and the carnitine transporter SLC22A5, accompanied by decreased expression of β-oxidation enzymes (ACADS, ACADM, ACADVL, HADHA, HADHB, HADH, EHHADH) and consistent downregulation of the medium-chain fatty acid activating enzyme ACSF2. In contrast, ACSL4, which specifically activates polyunsaturated fatty acids, showed consistent upregulation. This metabolic disruption was coupled with coordinated changes in membrane remodeling enzymes, with upregulation of LPCAT1 and downregulation of LPCAT3, suggesting systematic alterations in membrane phospholipid composition.

Conclusion

Our multi-cohort analysis reveals a specific pattern of metabolic disruption in UC that extends beyond pathway inhibition. The coordinated upregulation of the ferroptosis mediator ACSL4 together with systematic changes in membrane remodeling enzymes suggests active metabolic rewiring that could promote ferroptotic cell death through altered membrane phospholipid composition and increased susceptibility to lipid peroxidation. These findings highlight potential new therapeutic targets in UC focused on specific aspects of lipid metabolism and ferroptosis regulation.
P0099 Histone H4 lysine 12 lactylation in CD4+ T cells promotes the progression of Ulcerative Colitis through PKM2/glycolysis loop and PKM2/STAT3 signaling pathway
Authors: Xu S , Ye L , Wu J , Tao H , Li L , Lu H , Wang F
Published: January 2025

Background

Immune dysfunction- the imbalance of Th17/Treg ratio is the main pathogenic factor of ulcerative colitis (UC). Histone lactylation is a new protein modification and could regulate immune function. However, the roles of histone lactylation in the naïve CD4+ T cell differentiation and UC progression remain unclear.

Methods

We employed a mouse model to elucidate the mechanism by which lactic acid facilitates the progression of ulcerative colitis through the inhibition of PKM2 and targeted knockout of Pkm2 in CD4+ T cells.

Results

Our study shows a high level of H4K12la in CD4+ T cells at the intestinal inflammatory sites in UC, which is specifically enriched at the promoters of glycolytic genes including pyruvate kinase 2 (PKM2). Then PKM2 can activate the transcriptional activation protein 3 (STAT3) signaling pathway, thereby inducing the differentiation of naïve CD4+ T cells into Th17 cells and inhibiting Treg cell differentiation, and cause sustained release of pro-inflammatory cytokines, which finally exacerbates intestinal inflammation. In addition, as a key glycolysis enzyme, the upregulation of PKM2 expression could accelerate more lactate production in a positive feedback way. Both pharmacologic inhibition of PKM2 and CD4+ T cell-specific ablation of Pkm2 could block lactate production and then downregulate the ratio of Th17/Treg to alleviate colitis.

Conclusion

The study demonstrate the pro-inflammatory role of H4K12la in CD4+ T cells, and PKM2 may be a potential target for the treatment of UC.
P0100 Intestinal adaptation in a mouse model of Crohn’s- like ileitis under short bowel conditions
Authors: Jadzewski E , Reiner J , Lamprecht G , Witte M , Berlin P
Published: January 2025

Background

Short bowel syndrome (SBS) is a rare and complex condition that can occur after ileo caecal resection (ICR), which is often performed in Crohn’s disease (CD) patients. The disease outcome depends on the postsurgical anatomy as well as individual risk factors that may impede intestinal adaptation. The objective of this study was to investigate intestinal adaptation following ICR in a CD mouse model.

Methods

SAMP1/YitFc (SAMP1, n=37) mice with histologically manifest ileitis and parental controls (AKR, n=34) of both sexes were subjected to 40% ICR or transection (sham) at the age of 14-20 weeks. Intestinal continuity was established by end-to-end jejunocolic anastomosis. Clinical data and stool samples were collected for either 7 or 14 days. Histomorphological adaptation and intestinal inflammation were examined by histological evaluation of residual jejunal and colonic sections as well as by analysis of blood parameters and cytokine mRNA expression in mesenteric lymph nodes (MLN).

Results

This study was the first to examine adaptation in a CD mouse model. At the age of 14 weeks SAMP1 mice exhibited spontaneous ileitis, with characteristics similar to CD (hypertrophy of muscularis, dysplasia of paneth cells, transmural infiltration, villus blunting). Following surgery, SAMP1 mice showed higher mortality after surgery in ICR and sham groups (both 33%) compared to AKR (21% ICR, 0% sham). ICR resulted in the manifestation of SBS, displayed by body weight loss and diarrhea in both strains. SAMP1 mice exhibited a higher food intake and demonstrated less weight loss than AKR mice. However, the level of wellbeing was significantly lower in comparison to AKR after ICR (p<0.0001 d7, d14). Histomorphological adaptation of the remnant jejunum was worse in SAMP1 mice (villus height SAMP1 229 µm vs. AKR 376 µm, p<0.01). Following ICR, SAMP1 mice exhibited normalization of preoperatively increased inflammatory values in the blood (neutropenia, lymphocytosis) and a reduction of Il4 and Infγ mRNA expression in MLN after ICR (p<0.05 SAMP1 vs. AKR).

Conclusion

The SAMP1/YitFc mouse is a suitable model for investigating the mechanisms of intestinal adaptation under the influence of experimental chronic ileitis. Subsequent research will focus on the alteration of the inflammatory environment and mucus barrier of the remaining bowel following resection in this model.
P0105 Evaluation of Stimuli Driving Oncostatin M Expression in Bone Marrow-Derived Macrophages
Authors: Velasco Blázquez L , Cancino C , Luo Y , Konopka A , Hegazy A N
Published: January 2025

Background

Oncostatin M (OSM) is a cytokine linked to inflammatory diseases, including inflammatory bowel disease (IBD), where it contributes to inflammation, tissue remodeling, and fibrosis. Despite its established role, the specific signals driving OSM expression in colitis remain unclear.

Methods

Bone marrow-derived macrophages (BMDMs) were differentiated using M-CSF and stimulated for 36 hours with a range of Toll-like receptor (TLR) agonists, damage-associated molecular patterns (DAMPs), cytokines, and bacterial lysates. OSM secretion was quantified using enzyme-linked immunosorbent assays (ELISA). To dissect key signaling pathways, we applied chemical inhibitors and utilized macrophages derived from gene-deficient mice.

Results

Myd88-dependent stimuli, including TLR1/2 (Pam3CSK4), TLR4 (LPS), TLR2/6 (FSL-1), TLR7/8 (R848), IL-1α, and IL-33, significantly increased OSM expression in BMDMs. Gram-negative (E. coli, C. rodentium) and Gram-positive (S. aureus) bacterial lysates also enhanced OSM secretion. Pro-inflammatory cytokine IFN-γ further boosted OSM levels, consistent with in vivo findings of OSM upregulation in inflammatory monocytes. Additionally, IL-4, which induces a tissue repair phenotype in macrophages, markedly increased OSM secretion.

Conclusion

OSM expression in BMDMs is driven by multiple signaling pathways, indicating a synergistic effect of diverse stimuli. Identifying key stimulatory and inhibitory molecules, alongside macrophage-specific knockout analyses, will help clarify the upstream regulators of OSM. Understanding these drivers may uncover new therapeutic targets in IBD and offer insights into the onset of fibrotic processes.
P0109 SEMA3B is related to anti-TNF therapy response in Ulcerative Colitis patients but shows no relevant outcomes in modulating intestinal inflammation in vivo
Authors: Arosa García L , Malvar-Fernández B , García S , Conde-Aranda J ,   Molecular and Cellular Gastroenterology Group
Published: January 2025

Background

Semaphorins are a large family of proteins originally linked to the development of the nervous system. Recently, class 3 semaphorins (SEMA3A-3G) have been identified as potential regulators of various biological processes underlying inflammation, including the modulation of immune cell activation and migration. However, the relationship between SEMA3B and Ulcerative Colitis (UC), as well as its contribution to intestinal inflammation, remains poorly understood. To address these knowledge gaps, we conducted a comprehensive transcriptomic analysis using publicly available datasets containing expression profiles of colonic tissue, complemented by in vivo experiments.

Methods

We analysed publicly available microarray and RNAseq datasets of colon biopsies [GSE38713, GSE59071, GSE12251, GSE16879, GSE73661 (Gene Expression Omnibus), and E-MTAB-7875 (European Bioinformatics Institute)]. Furthermore, ten to twelve-week-old female C57BL/6 mice (n=18) were subjected to DSS-induced acute colitis by administering 1.5% DSS in the drinking water for 7 days. Mice were treated daily with either IgG2A (50 µg/day/mouse) or SEMA3B (50 µg/day/mouse). After euthanization, we performed histology studies and analysed the inflammatory cell infiltrate using flow cytometry. Also, colonic gene expression was measured by RT-qPCR, and the integrity of the epithelial barrier was assessed by western blot.

Results

Transcriptomic analyses revealed that SEMA3B expression was downregulated in UC patients compared to healthy controls. Several receptors related to SEMA3B also exhibited dysregulated expression between UC and non-IBD controls. In the same way, UC patients who did not respond to infliximab showed reduced baseline transcript levels of that class-3 semaphorin. These patient-derived data suggest that SEMA3B could be an interesting biomarker in the context of intestinal inflammation. However, we also decided to study whether SEMA3B had a functional impact on the onset of colitis. Contrary to the human data, administering recombinant SEMA3B to mice subjected to DSS-induced acute colitis did not modify the course of the disease, epithelial barrier integrity or the expression of inflammatory markers. We only found a significant reduction in neutrophil abundance in the colonic lamina propria after recombinant SEMA3B administration.

Conclusion

Overall, our findings demonstrate that SEMA3B expression is altered in the inflamed colonic mucosa of patients with UC and may serve as a biomarker for response to anti-TNF therapy. However, the direct impact of this class-3 semaphorin on disease progression in vivo appears to be limited.
P0110 Effect of Tofacitinib on Hemostasis in Patients with Ulcerative Colitis: a Comparative Ex Vivo Study
Authors: Baldan-Martin M , Sanchez Sanchez C , Suarez Trujillo F , Ramírez C , Soleto I , Mercado J , Orejudo M , Martínez P J , Rubio Collado C , Orts M , Rubio Franco M J , Planas A , Acedo N , Butta N , Chaparro M , Gisbert J P ,   *Authors share co-senior authorship
Published: January 2025

Background

Tofacitinib, a small-molecule Janus kinase inhibitor (JAKi), has been shown to be effective in the treatment of ulcerative colitis (UC). Despite its benefits, a higher incidence of thromboembolic events has been reported in patients treated with tofacitinib. It has been suggested that this effect might be a class effect and could affect other JAKi. Consequently, the regulatory agencies warned about its risks and restricted its conditions of use. Therefore, it would be highly relevant to understand the pathophysiological mechanism involved in this potential increase in thromboembolic events to determine the consequences in clinical practice.

Methods

In this study, we analyzed the effect of tofacitinib on platelet function and global hemostasis in 10 patients with active UC (aUC), 10 patients with quiescent UC (qUC), and 10 healthy controls (HC), under experimental conditions that minimized inter-individual variability as a result of the treatment. To know the specific effect of tofacitinib, we included an anti-TNF drug as a comparator. We performed platelet aggregometry, platelet activation assays, and rotational thromboelastometry (ROTEM).

Results

ROTEM results did not reveal significant differences between the tofacitinib and anti-TNF groups across different study groups of patients (Table 1). Platelet aggregation analysis showed no statistically significant differences between platetel-rich plasma samples incubated with tofacitinib, anti-TNF or sterile water (control group) in aUC, qUC and HC groups (Figure 1). Flow cytometry analysis of platelet activation demonstrated increased expression of activation markers CD62P and CD63 and of the binding of PAC-1 in platelets from both aUC and qUC patients incubated with tofacitinib and anti-TNF, compared to the control group. There were no differences in these parameters between the two drugs. Additionally, an increase in CD63 expression was also observed in the HC group (Figure 2).

Conclusion

The results of this study suggest that tofacitinib does not significantly alter platelet function in platelet-rich plasma or affect global coagulation in whole blood. However, future in vivo studies are necessary to corroborate these findings in patients treated with tofacitinib and to assess the long-term effects of tofacitinib on hemostasis.
P0111 Patient reported outcome measures (PROM) in patients scheduled to undergo bowel resection for Crohn’s disease
Authors: Schmitz A , Bercher M , Iesalnieks I , Hinrichs N
Published: January 2025

Background

Indication for surgery in Crohn’s disease patients is a matter of ongoing debate. Increasing number of available medical treatments can lead to significant postponement of surgery in many patients. Later first abdominal surgery for Crohn’s disease is commonly seen as significant achievement of modern biological treatment. However, later surgery is not necessarily a success since it might only prolong unnecessary suffering. Thus, it is of a paramount importance to understand whether patients are “losing” or “winning” time by avoiding abdominal surgery. Patient reported outcome measurement – various indices, scores and Quality-of-Life measurement tools – are used to assess the degree of suffering and to calculate the treatment success. In present prospective study, we assessed the value of commonly used PROM tools to characterize disease severity in patients scheduled for bowel resection for Crohn’s disease.

Methods

Consecutive patients scheduled for bowel resection were assessed preoperatively using CDAI (Crohn’s disease activity index), IBD-DI (IBD Disability index) and the IBDQ (IBD questionnaire to assess quality of life). Also, patients were asked to rate their global health (GH) from 1 (unbearable) to 10 (perfectly good).

Worse scoring was expected to be found in patients with disease complications which are frequent in surgical population: severe anemia (HB <10g/dl) weight loss of >10%, penetrating disease, intraabdominal abscess and emergency hospitalization before surgery.

Results

109 patients were assessed.

Conclusion

PROM’s alone are not sufficient to guide the decision toward or against the potential surgery since “good” scores still miss some significant disease complications. Also, PROM’s are dynamic tools with scores differing significantly over time. Indication for surgery should be rather guided by expected risks and prognosis than by mere “disease activity”.

Table 1 illustrates preoperative results of PROM’s assessment. An incongruence of all scores can be observed. While 34% of patients have a quiescent disease according to the CDAI, only 13.5 % according to IBD-Q.

Table 2 demonstrates great inconsistency between the tools regarding their ability to predict severe disease (as illustrated by emergency hospitalization, significant weight loss, presence of intraabdominal abscess and penetrating disease). Only severe anemia led to significant worsening in all calculated tools.
P0115 Selective immune responses to Lachnospiraceae flagellins discriminate therapy-naive pediatric Crohn’s disease patients with distinct host-microbial interaction
Authors: Barendregt D , Joosse M E , Hulleman-van Haaften D H , Costes L M M , Gacesa R , Plomp N , Duck L W , Klomberg R C W , Vuijk S A , Doukas M , Escher J C , Harmsen H J M , Elson C O , de Ridder L , Samsom J N
Published: January 2025

Background

Pathogenic CD4+ T-cell responses to commensal microbial antigens drive intestinal inflammation in Crohn’s disease (CD). Both hypo- or hyperactive anti-microbial innate immunity could underlie these aberrant T-cell responses. CD patients have increased IgG and T cell responses against commensal Lachnospiraceae-derived flagellins, which associate with disease complications. We investigated whether CD patients with high anti-Lachnospiraceae flagellin responses at diagnosis have underlying innate hypo- or hyperresponsiveness and high IgG responses to other dysbiotic commensals.

Methods

IgG reactivity to 19 recombinant flagellins from Lachnospiraceae species colonizing mouse and human gut, was measured in plasma of therapy-naïve pediatric CD patients (n=49) and controls (n=29). In addition, we measured plasma IgG responses to 1 recombinant flagellin and 71 microbial lysates of dysbiotic commensal species in therapy-naive pediatric CD patients (n=103) and controls (n=61). IgG responses were related to immunological and clinicopathological parameters.

Results

CD patients had significantly higher IgG responses to 12/19 Lachnospiraceae-derived flagellins compared to controls. Multi-reactivity to more than 10 flagellins was common in CD (41%) and associated with increased circulating flagellin-specific memory CD4+ T-cell frequencies. Multi-reactivity, and even single-reactivity to recombinant flagellin, correlated with reduced immune cell infiltration and epithelial damage, and fewer calprotectin-positive neutrophils in colonic lesional tissue, based on histological severity scoring and immune histochemistry, respectively. As these data may argue that high anti-flagellin IgG reactivity relates to innate hyporesponsiveness, we next assessed whether patients had a generalized high IgG response to lysates of dysbiotic intestinal bacteria. Hierarchical clustering identified subgroups of CD patients with different patterns of significantly increased anti-commensal IgG responses. Patients with high anti-Lachnospiraceae flagellin IgG also had high IgG responses against lysate of Roseburia inulinivorans, a Lachnospiraceae species. Of these anti-flagellin high responders, two-thirds responded to many commensals while one-third did not, arguing against a generalized high anti-commensal IgG response.

Conclusion

In conclusion, high IgG responses to Lachnospiraceae-derived flagellins identify a subgroup of pediatric therapy-naive CD patients with features of innate hyporesponsiveness. These patients do not have uniformly high IgG responses to other dysbiotic commensals, arguing that disturbed host-microbiota responses in CD are highly personalized and do not stem from an overall failure in microbiota-host crosstalk.
P0117 Exploring the role and mechanism of leukotriene D4 in fistulizing Crohn's disease based on multi-omics research
Authors: Zhang C
Published: January 2025

Background

Alterations in the gut microbiota and its metabolites are involved in the pathogenesis of Crohn's disease (CD). In a study targeting patients with different phenotypes of CD, we investigated the characteristics of the gut microbiota and metabolites between Crohn's disease with fistula and Crohn's disease without fistula.

Methods

We divided the research subjects into three groups, including 11 CD patients with fistulas, 9 CD patients without fistulas, and 5 healthy individuals (control group). Stool samples from patients were collected and sequenced. The fecal microflora was analyzed by 16S ribosomal RNA gene amplification sequence, and the metabolites were quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS). Bioinformatics analysis was employed to explore the microbial and metabolite characteristics of CD fistulas. Then, we further verified through mouse experiments and cell experiments.

Results

Compared with healthy controls, CD patients mainly showed a reduction in the Firmicutes phylum and an increase in the Proteobacteria phylum. The reduction of these short-chain fatty acid-producing bacteria and the increase in harmful bacteria are likely important factors leading to CD. Compared with non-fistula patients, the beneficial bacteria such as the genus Romboutsia in fistula patients were significantly reduced. In addition, we also found structural disruption and functional dysregulation of microorganisms in fistula patients. Metabolomics analysis indicated that the increase in pro-inflammatory metabolites such as leukotriene D4 is a specific change in fistula. Spearman correlation analysis showed that the reduction of beneficial bacteria was significantly negatively correlated with the increase in leukotriene D4, suggesting that the reduction of beneficial bacteria may lead to an increase in leukotriene D4 and thus promote the formation of fistulas. In vitro experiments further demonstrated that leukotriene D4 can delay the healing of fistula in mice. Cell experiments also proved that leukotriene D4 can reduce the expression of E-cadherin and upregulate the expression of EMT-related genes (snail, vimentin). Transcriptome analysis revealed that leukotriene D4 may lead to the formation of fistulas by activating the AGE-RAGE signaling pathway in diabetic complications.

Conclusion

In CD patients, the reduction of beneficial bacteria may promote the upregulation of leukotriene D4, thus promoting the formation of fistula.
P0129 Distinct involvement of plasma cells and monocytes/macrophages in ileal and colonic ulcer formation in patients with Crohn's disease
Authors: Pierre Dr. N , Jacobs N , Fernández-Verdejo R , Louis E , Vieujean S
Published: January 2025

Background

Despite its interest for the development of personalised medicine, the pathophysiological distinctions between ileal and colonic Crohn’s disease (CD) have been poorly characterised. This study aims to search for immunological differences between ileal and colonic CD.

Methods

We reanalysed our proteomic dataset1 to extract non-exploited immunological information. Using mass spectrometry-based proteomics, we previously compared the proteome of ulcer edges and adjacent normal mucosa (paired design) in the ileum (n=16 biopsies) and colon (n=16 biopsies) of 16 CD patients (Figure 1). A total of 4,428 and 5,204 proteins were screened in the ileum and colon, respectively. To identify proteins specific to particular immune cell populations, we searched in the Human Proteome Atlas and literature.

Results

We identified markers specific to plasma cells (IgA1, IgM, IgG1, IgG2, IgG3, IgG4, immunoglobulin J chain [IGJ], and immunoglobulin lambda-like polypeptide 5 [IGLL5]), monocytes/macrophages (cluster of differentiation 14 [CD14]), and mast cells (chymase [CMA1], mast cell carboxypeptidase A [CPA3], and tryptase alpha/beta-1 [TPSAB1]). No specific markers were identified for the other immune cells. The number of increased plasma cell markers (ulcer edges vs adjacent normal mucosa) was higher in the ileum (IgA1, IgM, IgG1, IgG2, IgG3, IGLL5, and IGJ) than in the colon (IgG3) (Figure 2). Of note, immune exclusion markers (IgM, IgA1, IGJ) were increased in the ileum, but not the colon (ulcer edges vs adjacent normal mucosa). The marker of monocytes/macrophages CD14 was increased in the colon, but not in the ileum (ulcer edges vs adjacent normal mucosa) (Figure 2). Mast cells markers (CMA1, CPA3, and TPSAB1) showed no significant change in the ileum or colon (ulcer edges vs adjacent normal mucosa) (Figure 2).

Conclusion

Plasma cells and monocytes/macrophages may play distinct roles in the formation of ileal and colonic ulcers in patients with CD, suggesting further investigations.

References

1.Pierre N, Salée C, Massot C, Blétard N, Mazzucchelli G, Smargiasso N, et al. Proteomics Highlights Common and Distinct Pathophysiological Processes Associated with Ileal and Colonic Ulcers in Crohn’s Disease. J Crohns Colitis 2020;14(2):205–15.
P0130 Assessment of macrophage types in the intestinal tissue of treatment naïve Inflammatory Bowel Disease patients in relation to their disease and activation of the CCL2/CCR2 pathway
Authors: Begum J , Fatima A , Rimmer P , Iqbal T , Stoica V , Owusu M , Lelios I , McGettrick H , Welford R , Iqbal A
Published: January 2025

Background

Resident intestinal macrophages play a key role in maintaining gut homeostasis and exhibit a hypoactive tolerogenic phenotype. Recently, several subsets of intestinal macrophages have been identified based on CD11c expression which differ in their inflammatory and functional profiles. Notably, pro-inflammatory CD11c+ monocyte-like macrophages are found elevated in patients with inflammatory bowel disease (IBD), specifically Ulcerative colitis (UC) and Crohn’s disease (CD). These cells are recruited from blood monocytes via the CCR2/CCL2 chemokine pathway. Our study is focused on observing the patterns of CCL2-driven blood monocyte migration and their translation into subsets of intestinal tissue macrophages that can determine the degree of gut inflammation in newly diagnosed patients.

Methods

Patients referred with suspected IBD were seen in an inception clinic. Intestinal biopsies and matched blood samples were obtained from pre-treatment UC and CD patients during their index colonoscopy. Those with inflammation excluded during this procedure formed a ‘non-IBD’ control group. Biopsy segments were cultured to generate conditioned media and also digested for flow cytometry analysis. Plasma concentrations of CCL2 and intestinal secretome were measured using ELISA or Olink proteomic analysis respectively. Efficacy of blood monocyte chemotaxis towards CCL2 was assessed in the presence or absence of CCL2/CCR2 antagonists and the profile of monocyte subsets in whole blood were determined using whole blood flow cytometry analysis.

Results

As previously described, we observed distinct CD11c+ and CD11c- macrophage populations in IBD intestinal tissue, with expansion of the CD11c+ subset within inflamed regions which expressed higher levels of the chemokine receptors CCR2 and CX3CR1. Higher concentrations of CCL2 were observed in conditioned media from inflamed IBD tissue compared to non-inflamed regions and this correlated with elevated numbers of circulating blood monocytes. Chemotaxis assays revealed a corresponding increase in CCL2-induced monocyte migration in patients with IBD compared to the ‘non-IBD’ control group.

Conclusion

Our study provides further insights into the role of the CCL2/CCR2 chemokine axis in driving monocyte recruitment and their differentiation into pro-inflammatory intestinal macrophages in IBD. We demonstrate that inflamed intestinal regions exhibit elevated levels of CCL2 correlating with an expansion of the CD11c⁺ macrophage subset and increased CCL2-driven monocyte migration in these subjects. These findings underscore the significance of targeting the CCL2/CCR2 pathway and that it might be an important driver in the development IBD.