Introduction

Management of perianal fistulas in Crohn’s disease (CD) is challenging and requires a multidisciplinary approach, combining surgical drainage and biologic therapies, such as infliximab (IFX). Higher IFX trough concentrations have been associated with improved fistula healing rates. The subcutaneous (SC) formulation of IFX achieves 2–3 times higher and more stable trough levels compared to intravenous (IV) formulation. This study hypothesizes that SC IFX could enhance perianal fistula healing rates in CD patients.

Aims & Methods

REMSILAP study is part of the 3TLAP cohort, a French prospective multicenter observational study evaluating optimal therapeutic strategies for achieving clinical and radiological remission of perianal fistulas in CD at 12 months post-surgical drainage. The REMSILAP substudy focuses specifically on patients receiving SC IFX. Patients who received SC IFX after or within six months prior to surgical drainage were included. Baseline was defined as the day of surgical drainage. The primary outcome was the proportion of patients achieving complete clinical remission defined as Perianal Disease Activity Index (PDAI) fistula drainage subscore = 0 associated with PDAI activity restriction subscore <3 and absence of seton, and radiological remission at 12 months. Here, we present preliminary findings from REMSILAP.

Results

Among the 353 patients enrolled in the 3TLAP cohort, 54 were included in REMSILAP. The cohort consisted of 61.1% male patients, with a median age of 36 years and a median disease duration of 4.5 years. Penetrating disease (B3 phenotype) was present in 40.7%, and 33.3% had a history of surgical resection. At baseline, 40.7% of patients had quiescent disease regarding Harvey-Bradshaw index, while 5.6% had severe disease activity. Biologic exposure prior to inclusion was noted in 42.6%. Surgical drainage, with seton placement, was performed in 74.1% of patients. Forty-eight patients (88%) initiated SC IFX treatment after surgical drainage. Of the patients receiving SC IFX, 50% transitioned to SC IFX after less than three IV infusions. Among those on IV IFX at baseline, 20.4% were receiving a 10 mg/kg dose. Forty-three patients (79.6%) received SC IFX in combination with immunomodulators (azathioprine, methotrexate, or 6-mercaptopurine). The median duration of SC IFX treatment was 13.1 months, with treatment maintained for 67.5% of the follow-up period (mean: 19.3 ± 11.3 months). Forty-three patients (79.6%) were treated with a stable dose of 120 mg/14 days and 6 patients (11.1%) had an intensification of SC IFX dosage to 120mg / 7 days. At 12 months, 42 patients were evaluable for clinical outcomes. Complete clinical healing at 12 months was achieved in 11 patients (27.5%) and association of PDAI restriction subscore <3 and drainage subscore = 0 was found in 18 patients (42.9%). Thirteen patients (34.2%) from the 25 patients who had received at least 6 months of SC IFX treatment showed clinical healing at 6 months. Out of the 26 patients treated with at least 12 months of SC IFX treatment, clinical healing was achieved in 16 patients (61.5%) at 12 months. Among the 11 patients with clinical healing at 12 months, 8 (72.2%) were treated with SC IFX treatment following more than three IFX IV infusions. None of the 11 patients with available MRI date showed radiological healing at 12 months.

Conclusion

Subcutaneous infliximab following surgical drainage of Crohn’s disease perianal fistula demonstrates high treatment persistence and promising rates of fistula healing.

Disclosure

This study was funded by Celltrion Healthcare France

Introduction

Very early onset inflammatory bowel disease (VEO-IBD) is often associated with a severe disease course and unique characteristics including an underlying monogenic defect. In this study, we identified new pathogenic mutations in CGNL1 associated with VEO-IBD and other inflammatory GI disease. CGNL1 (Cingulin Like 1) encodes an epithelial junctional protein whose function was previously unknown in the gastrointestinal tract.

Aims & Methods

Whole exome sequencing (WES) was performed on the affected patient with VEO-IBD and all first-degree relatives with IBD and other inflammatory disease. Intestinal epithelial organoids (IEOs) were generated from the affected patient and were characterized by transepithelial electrical resistance (TEER), FITC-dextran permeability assay on epithelial cell monolayer, immunostaining, RNA sequencing, and transmission electron microscopy (TEM). In addition, we generated a new Cgnl1^-/- mouse model, which was characterized using FITC-dextran permeability assay, TEM, dextran-sodium sulfate (DSS)-induced colitis, and infections by Citrobacter rodentium and Clostridioides difficile. Single-cell datasets were analyzed to determine CGNL1 expression in IBD, primary sclerosing cholangitis (PSC), and autoimmune hepatitis (AIH).

Results

In the affected patient with VEO-IBD who required early total colectomy and pouch formation with coexistent PSC and celiac disease, WES identified two rare, new, pathogenic variants in the CGNL1 gene. Both pathogenic variants were also present in the patient’s younger sister, who has a similar history including early-onset, fulminant ulcerative colitis requiring total colectomy with ileostomy and PSC-AIH overlap syndrome. Furthermore, multiple relatives of the patient suffer from IBD and other inflammatory conditions including celiac disease, eosinophilic esophagitis, and type-1 diabetes. The RNA and protein levels of CGNL1 were significantly diminished in the patient’s intestinal epithelial cells compared to that of healthy individuals and other IBD patients by RNA-seq, immunoblotting, and immunostaining. The patient’s IEOs from pouch body and pre-pouch ileum formed smaller 3D spheroids with altered cell composition and significantly impaired barrier function compared to those from healthy controls and other IBD patients. Immunofluorescence and TEM demonstrated that CGNL1 is required for the assembly of junctional complexes in human IEOs and an epithelial cell line. Similarly to findings from the patient, impaired junctional complexes in intestinal epithelial cells and elevated intestinal permeability were present in Cgnl1^-/- mice at steady state. Cgnl1^-/- mice showed substantial vulnerability to DSS-induced colitis and bacterial infections that directly compromise the epithelial barrier. In addition, 6-month-old Cgnl1^-/- mice exhibited spontaneous inflammation in the colon and terminal ileum due to disrupted intestinal barrier, which was microbiome-dependent. Furthermore, single-cell analysis revealed diminished expression of CGNL1 in the intestinal and hepatic epithelial cells from patients with IBD or PSC/AIH, respectively.

Conclusion

The pathogenic CGNL1 variants contribute to VEO-IBD by disrupting gut barrier integrity, as demonstrated by patient’s cells and novel murine models. This study expands our understanding of epithelial barrier impairment in the pathogenesis of VEO-IBD, and highlights intestinal epithelium as a therapeutic target in some IBD patients.

Introduction

A dysfunctional intestinal mucosal barrier is a key pathophysiological hallmark and driver of a broad range of gastrointestinal diseases including celiac disease and inflammatory bowel disease. To date, there are no adequate treatment strategies to ameliorate impaired barrier function.
IMU-856 is an orally available and systemically acting small molecule modulator of sirtuin 6 (SIRT6), a histone/non-histone protein deacetylase which serves as a transcriptional regulator of intestinal barrier function and regeneration of bowel epithelium. IMU-856 may represent a new approach to treat gastrointestinal diseases with compromised barrier function.

Aims & Methods

This was a first-in-human, double-blind, randomized, placebo-controlled clinical trial of IMU-856 in healthy volunteers and patients with celiac disease. In the multiple ascending dose part, healthy human subjects were dosed once-daily for 14 consecutive days with IMU-856 at three different dose levels or placebo. Additionally, the Phase 1/1b study was designed to assess safety and tolerability of IMU-856 at two different dose levels in patients with celiac disease during periods of gluten-free diet and a 15-day gluten challenge. Further objectives included pharmacokinetics and the assessment of histological changes. Biomarkers reflecting intestinal enterocyte mass and function, nutrient absorption, and enteroendocrine hormones like GLP-1 were analyzed to assess potential effects on gut health.

Results

IMU-856 was safe and well-tolerated with a benign adverse event profile and pharmacokinetics that allow once-daily dosing. Treatment with IMU-856 protected against gluten-induced histologic deterioration, improved the health and metabolic function of intestinal enterocytes as measured by nutrient uptake and citrulline [1], and had positive effects on enteroendocrine cells increasing endogenous GLP-1 levels in a dose-dependent manner.

Conclusion

IMU-856 is a safe, highly selective and potent epigenetic modulator, improving the intestinal barrier function in patients with celiac disease undergoing a gluten challenge.
Positive effects of IMU-856 on gut hormones and various biomarkers for overall gut health including intestinal function and integrity were observed. Therefore, IMU-856 may offer extensive potential for treatment of gastrointestinal diseases with compromised intestinal barrier function and metabolic diseases.

References

1. Daveson AJM, Stubbs R, Polasek TM, Isola J, Anderson R, Tye-Din JA, et al. Safety, clinical activity, pharmacodynamics, and pharmacokinetics of IMU-856, a SIRT6 modulator, in coeliac disease: a first-in-human, randomised, double-blind, placebo-controlled, phase 1 trial.

Disclosure

AS, MW, EP: employees of Immunic AG, option and shareholders of Immunic, Inc.
IPO, JF, IK, SE: employees of Immunic AG, option and/or shareholders of Immunic, Inc.
HK: employee of Immunic AG, shareholder of Immunic, Inc., co-inventor of patents for the drug in investigation
DP: option holder of Immunic, Inc.
DV, AM: employees of Immunic AG and Immunic, Inc., shareholders of Immunic, Inc., co-inventors of patents for the drug in investigation

Introduction

Microplastic particles (MPs), defined as plastic fragments smaller than 5 mm, are pervasive pollutants that accumulate in ecosystems and the human food chain (1). Literature points at various health risks, including the induction of carcinogenesis (2). Emerging evidence from animal models (3) suggests that MPs may influence the gut microbiome, but the impact on the human gut microbiome remains poorly understood.

Aims & Methods

This study aimed to evaluate how various MP types influence gut microbial composition and metabolism using an ex vivo bioreactor model, with a focus on exploring potential carcinogenic effects arising from MP–microbiome interactions.
Stool samples from healthy donors were used to inoculate bioreactor cultures, which were maintained under anaerobic conditions for five days with daily nutrient feeding. These cultures were exposed to five common MP types—polystyrene (PS), polypropylene (PP), low-density polyethylene (LDPE), poly(methyl methacrylate) (PMMA), and polyethylene terephthalate (PET)—at concentrations mimicking both estimated human exposure (4) and higher doses to assess dose-dependence. Cell viability and total bacterial counts, as well as culture pH, were measured throughout the experiment. To further explore potential microbiome and metabolic alterations, 16S rRNA gene sequencing and targeted metabolomics were performed.

Results

MP exposure did not lead to significant changes in total or viable bacterial cell counts. However, MP-treated cultures exhibited a consistent and significant decrease in pH compared to controls, suggesting changes in microbial metabolic activity. Microbiome sequencing revealed plastic-type-dependent alterations in microbial composition, with certain bacterial taxa increasing or decreasing in abundance depending on the MP type. These shifts occurred across multiple genera within diverse families, including Lachnospiraceae, Oscillospiraceae, Enterobacteriaceae, and Ruminococcaceae, with the majority of changes occurring withing the phylum Bacillota. These compositional changes were accompanied by shifts in the metabolomic profiles, some of which correlated with the observed pH changes. Several plastic types induced changes in valeric acid levels, while individual MP types were associated with alterations in distinct metabolites such as uracil, lactic acid, and acetic acid.

Conclusion

This study demonstrates that MPs can affect gut microbial activity and metabolism without significantly altering overall bacterial abundance in the short term. The variation in microbiome response across plastic types highlights the complexity of MP-microbiome interactions. Changes in faecal pH are known to be associated with various gastrointestinal diseases (5). Interestingly, some of the MP-induced changes in microbial composition resembled patterns linked to diseases such as depression and colorectal cancer. In contrast, other changes showed patterns that differed from those typically associated with conditions like Parkinson’s disease and irritable bowel syndrome, highlighting the complexity of these associations and the dependency on the context. The bioreactor model provided a controlled environment for identifying direct MP-microbiome interactions; however, in humans, additional factors like diet, immune response, and individual microbiome variations play a role in determining long-term effects. Exposure duration may also play a critical role in shaping the extent and nature of microbiome alterations (6), underscoring the need for further research into the effects of chronic MP exposure and associated health risks.

References

(1) Mamun, A. A., Prasetya, T. A. E., Dewi, I. R., & Ahmad, M. (2023). Microplastics in human food chains: Food becoming a threat to health safety. The Science of the total environment, 858(Pt 1), 159834. https://doi.org/10.1016/j.scitotenv.2022.159834
(2) Kumar, R., Manna, C., Padha, S., Verma, A., Sharma, P., Dhar, A., Ghosh, A., & Bhattacharya, P. (2022). Micro(nano)plastics pollution and human health: How plastics can induce carcinogenesis to humans?. Chemosphere, 298, 134267. https://doi.org/10.1016/j.chemosphere.2022.134267
(3) Hirt, N., & Body-Malapel, M. (2020). Immunotoxicity and intestinal effects of nano- and microplastics: a review of the literature. Particle and fibre toxicology, 17(1), 57. https://doi.org/10.1186/s12989-020-00387-7
(4) Senathirajah, K., Attwood, S., Bhagwat, G., Carbery, M., Wilson, S., & Palanisami, T. (2021). Estimation of the mass of microplastics ingested - A pivotal first step towards human health risk assessment. Journal of hazardous materials, 404(Pt B), 124004. https://doi.org/10.1016/j.jhazmat.2020.124004
(5) Yamamura, R., Inoue, K. Y., Nishino, K., & Yamasaki, S. (2023). Intestinal and fecal pH in human health. Frontiers in Microbiomes, 2, 1192316.
(6) Yin, L., Yang, M., Teng, A., Ni, C., Wang, P., & Tang, S. (2025). Unraveling Microplastic Effects on Gut Microbiota across Various Animals Using Machine Learning. ACS nano, 19(1), 369–380. https://doi.org/10.1021/acsnano.4c07885

Introduction

Inflammatory bowel disease (IBD) is a growing global health problem with increasing prevalence. Current therapeutic strategies for IBD are mainly aimed at modulating the dysregulated immune activity in the intestinal mucosa. Targeting the JAK/STAT signalling pathway has been shown to be highly effective in ulcerative colitis, but not in Crohn's disease (CD), where efficacy was found to be insufficient in the initiation phase of a clinical trial [1]. Failure of the therapeutic response in Crohn’s disease may be influenced by the unique immune microenvironments in the small and large intestine and their characteristic cytokine profiles and immune cell compositions.

Aims & Methods

To gain deeper insight into region-specific efficacy in the inflamed ileum versus colon, this study investigates the immunomodulatory effects of filgotinib, a Jak1 inhibitor, using precision-cut intestinal slices (PCIS) from patients with Crohn's diseases. PCIS are viable, ultra-thin human tissue slices that retain the original intestinal architecture ex vivo and contain important cell types, including resident immune cells.
PCIS were prepared from resected ileal and colonic tissue of CD patients. The slices were cultured ex vivo and stimulated with concanavalin A or anti-CD3/CD28 antibodies to induce T cell-driven inflammatory responses. Filgotinib (1-100 µM) was applied to assess the immunomodulatory effects of JAK1 inhibition following Concanavalin A preactivation. To exclude treatment-related toxicity, cellular integrity was evaluated using an LDH release assay. Tissue morphology was examined by H&E staining and immunofluorescence. The immune response was assessed by multiplex ELISA of 20 cytokines.

Results

After filgotinib treatment, primary tissue slices from the ileum and colon of CD patients remained viable. Regional morphological characteristics of ileum and colon tissue were preserved after ex vivo cultivation, with prominent villi and smaller crypts in the ileum, and larger, more frequent crypts and flattened villi in the colon. Compared to non-CD tissue slices, Crohn’s disease-related changes, such as immune cell accumulation, were also observed in CD tissue slices ex vivo. Upon T cell-specific stimulation with anti-CD3/CD28 antibodies, region-specific immune reactivity was observed. Colonic PCIS showed an increased release of IL-2 (~3-fold), IL-10 (~2‑fold) and TRAIL (~4-fold) compared to ileal PCIS, indicating a stronger involvement of Th and regulatory T cells in the colon. In contrast, ileal PCIS showed higher levels of MIP-3α (2-fold) and granzyme A (~8-fold) after stimulation, suggesting increased cytotoxic T cell activity in this region. Filgotinib treatment showed region-specific differences in its ability to modulate cytokine release in PCIS of CD patients. In colonic PCIS, filgotinib reduced the induced secretion of Th17-associated cytokines such as IL-17F and IL-22 by up to 95%, whereas in ileal PCIS it showed no effect on the same cytokines.

Conclusion

In conclusion, filgotinib exhibited more potent anti‑inflammatory effect on Th17 cells in the colon, and a markedly reduced efficacy in the ileum. This study demonstrates for the first time that precision-cut intestinal slices can be used to predict region-specific drug response in inflamed intestinal tissue ex vivo, underscoring the critical importance of region-specific immune profiling in IBD and highlight the limited efficacy of JAK1 inhibition in ileum. This ex vivo, patient-derived model represents a valuable platform for evaluating localised treatment efficacy and advancing personalised therapeutic strategies in IBD.

References

[1] Rogler G. Efficacy of JAK inhibitors in Crohn's Disease. J Crohns Colitis. 2020 Aug 1;14(Supplement_2):S746-S754. doi: 10.1093/ecco-jcc/jjz186