Introduction

Primary sclerosing cholangitis (PSC) is a progressive autoimmune cholestatic liver disease often associated with inflammatory bowel disease (IBD), particularly ulcerative colitis [1]. In PSC, reduced expression and function of the bile acid receptor GPBAR1 (TGR5) in cholangiocytes is associated with a dysfunctional gut–liver immune axis and impaired resolution of inflammation [2,3]. Parallelly, the transcription factor RORγt in Th17 cells sustains IL-17 perpetuating IL-23-driven intestinal [4] and liver inflammation [5]. While GPBAR1 mediates anti-inflammatory responses to secondary bile acids, RORγt governs Th17 differentiation and cytokine secretion. Recent clinical studies have demonstrated that IL-23 inhibitors, such as risankizumab [6] and mirikizumab [7], are effective in treating IBD, highlighting the significance of the IL-23/IL-17 axis. GPBAR1/RORγt dual simultaneous modulation represents a novel strategy to counteract the fibrotic and inflammatory environment characteristic of PSC.

Aims & Methods

We evaluated the therapeutic efficacy of PBT002, a dual GPBAR1 agonist and RORγt inverse agonist, in modulating immune and fibrotic pathways in PSC. Transcriptomic distribution of target genes was assessed using publicly available single-cell RNA-sequencing datasets from healthy human livers [8]. Differential gene expression was validated in two independent cohorts of patients with PSC and PBC, and further confirmed in an external validation cohort (GSE159676). Functional studies were performed in vitro using primary human cholangiocytes (NHC), immortalized hepatic stellate cells (LX-2), primary monocyte-derived macrophages and CD4+ T lymphocytes. In vivo efficacy was assessed in Abcb4^⁻/⁻ mice treated with PBT002 (10 mg/kg/day) for 12 weeks.

Results

Single-cell transcriptomic analysis revealed that IL-17 and IL-23 cytokines are predominantly expressed by immune cells, whereas their receptors (IL23R, IL17RA, IL17RC, IL17RE) are enriched in epithelial cells, including hepatocytes and cholangiocytes. Deconvolution analysis of liver bulk transcriptomes from PSC and PBC cohorts showed features of immune exhaustion, with a mild upregulation of pro-inflammatory markers and IL-17 receptor subunits, along with prominent overexpression of PD-L1, a known pro-fibrotic mediator. In vitro, exposure of hepatic stellate cells, macrophages, and CD4+ T cells to supernatants from inflamed cholangiocytes induced strong activation, which was reversed by PBT002 treatment. In vivo, PBT002 significantly reduced hepatocellular damage, as shown by decreased serum ALT, AST, ALP, and bilirubin levels. Histological analyses revealed marked reductions in periductal inflammation and liver fibrosis. Gene expression profiling confirmed significant downregulation of M1 and Th17-associated genes (Rorc, Il17f, Il22, Il23a) in colon and liver. Bile acid profiling showed restoration of key GPBAR1 agonists and RORγt antagonists (DCA, 3-oxo-DCA, allo-LCA), while microbiota analysis demonstrated increased abundance of protective taxa (e.g., Blautia, Sutterellaceae), inversely associated with disease severity.

Conclusion

PBT002 exerts potent immunomodulatory effects in experimental PSC by rebalancing M1/M2 and Th17/Treg homeostasis through dual GPBAR1 activation and RORγt inhibition. These effects correlate with restoration of bile acid and microbiota profiles, confirming the key role of the microbiota–bile acid–immune axis in PSC and supporting PBT002’s clinical development for immune-mediated cholangiopathies, particularly in PSC-IBD overlap.

References

1. Fiorucci, S. et al. Bile Acids-Based Therapies for Primary Sclerosing Cholangitis: Current Landscape and Future Developments. Cells 13, (2024).
2. Di Giorgio, C. et al. Liver GPBAR1 Associates With Immune Dysfunction in Primary Sclerosing Cholangitis and Its Activation Attenuates Cholestasis in Abcb4-/- Mice. Liver Int. Off. J. Int. Assoc. Study Liver 45, e16235 (2025).
3. Reich, M. et al. Downregulation of TGR5 (GPBAR1) in biliary epithelial cells contributes to the pathogenesis of sclerosing cholangitis. J. Hepatol. 75, 634–646 (2021).
4. Biagioli, M. et al. Development of dual GPBAR1 agonist and RORγt inverse agonist for the treatment of inflammatory bowel diseases. Pharmacol. Res. 208, 107403 (2024).
5. Garcia Moreno, A. S. et al. IL-17 signaling in primary sclerosing cholangitis patient-derived organoids. Hepatol. Commun. 8, (2024).
6. Louis, E. et al. Risankizumab for Ulcerative Colitis: Two Randomized Clinical Trials. JAMA 332, 881–897 (2024).
7. D’Haens, G. et al. Mirikizumab as Induction and Maintenance Therapy for Ulcerative Colitis. N. Engl. J. Med. 388, 2444–2455 (2023).
8. Andrews, T. S. et al. Single-Cell, Single-Nucleus, and Spatial RNA Sequencing of the Human Liver Identifies Cholangiocyte and Mesenchymal Heterogeneity. Hepatol. Commun. 6, 821–840 (2022).

Introduction

Current therapies for inflammatory bowel disease (IBD) suppress inflammation rather than inhibiting underlying microbial drivers. Treatment failures of frontline interventions, including corticosteroids, can lead to dose escalation and risk of adverse effects.^1,2 Bacteria with pro-inflammatory potential, like adherent-invasive Escherichia coli (AIEC), have been postulated as a possible microbial driver in Crohn’s disease (CD), however, targeting these bacteria with precision in IBD remains challenging.^3,4 Most antibiotics have broad-spectrum activity and disturb the background microbiome, which may exacerbate inflammation.⁵ Attention has shifted towards bacteriophages, yet their underlying mechanisms of treating IBD, and how they may work as an adjunctive therapy, remains elusive.

Aims & Methods

We aimed to assess whether and how phage therapy, specific for a CD-associated bacterium, reduces colitis severity using gnotobiotic mouse models.
In vitro kill curves and biofilm challenges were used to identify lytic phage candidates. Adult germ-free C57BL/6 mice were colonized with altered Schaedler-flora (ASF) and E. coli NRG857c (NRG), a CD-associated isolate. After 3 weeks, mice were treated with an NRG-specific lytic phage (1x10⁹ PFU/dose; daily or TIW) or vehicle (PBS) for 2 weeks (n=6/group) and then exposed to 1 cycle of dextran sulfate sodium (2%; DSS) in drinking water. PBS-treated mice (n=6) not exposed to DSS served as controls. Phage treatment was also tested in a spontaneous model of colitis using C57BL/6NTac-Il10^em8Tac (IL-10^-/-) mice, treated weekly. Mice were monitored daily for weight, stool consistency, and occult blood. Fecal contents were cultured to determine bacterial load, and the expression of NRG fimS was quantified using qPCR as an assessment of virulence. At endpoint, colon tissues were collected for histological and immunohistochemistry analysis to quantify colitis severity and NRG infiltration, respectively. Additional C57BL/6 mice were colonized and treated as previously described. During colitis induction, mice received a low-dose of budesonide (2μg/day)⁶ (n=5) or vehicle (n=5) until endpoint. Mice were monitored daily for disease activity and colon tissues were collected for histological analysis. HPLC was used to determine active budesonide levels.

Results

HER259 was identified as a lytic phage against CD-associated AIEC NRG. In ASF and NRG colonized mice, HER259 reduced clinical symptoms (p< 0.001, p< 0.001) and histological scores (p< 0.0001, p< 0.001) in chemical induced and spontaneous colitis, respectively. A 1-log reduction in NRG bacterial load was observed in HER259-treated mice (p< 0.001). Reisolated NRG exhibited a reduced FimS ON/OFF ratio (p-value < 0.01). Immunohistochemistry revealed reduced infiltration of NRG into the lamina propria following HER259 treatment, with greater accumulation in the epithelium. HER259 treatment increased the efficacy of a sub-therapeutic dosing regimen of budesonide (p< 0.001), which was independent of microbial-based drug metabolism as determined by HPLC.

Conclusion

Our results demonstrate that lytic phage targeting a CD-associated bacterium attenuates colitis in two gnotobiotic mouse models. The intervention did not lead to complete eradication of the disease-driving agent, but instead modulated bacterial virulence mechanisms and enhanced responses to corticosteroid therapy. The data suggests that alternative mechanisms should be considered when translating phage therapy to treat IBD in clinical trials.

References

1. Yan, Y. et al. Commensal bacteria promote azathioprine therapy failure in inflammatory bowel disease via decreasing 6-mercaptopurine bioavailability. Cell Rep Med 4, 101153 (2023).
2. Nagayama, M., Gogokhia, L. & Longman, R. S. Precision microbiota therapy for IBD: premise and promise. Gut Microbes 17, 2489067 (2025).
3. Darfeuille-Michaud, A. et al. High prevalence of adherent-invasive Escherichia coli associated with ileal mucosa in Crohn’s disease. Gastroenterology 127, 412–421 (2004).
4. A, D.-M. et al. Presence of adherent Escherichia coli strains in ileal mucosa of patients with Crohn’s disease. Gastroenterology 115, 1405–1413 (1998).
5. Nelson, R. L., Suda, K. J. & Evans, C. T. Antibiotic treatment for Clostridium difficile-associated diarrhoea in adults. Cochrane Database Syst Rev 3, (2017).
6. Bercik, P. et al. Chronic gastrointestinal inflammation induces anxiety-like behavior and alters central nervous system biochemistry in mice. Gastroenterology 139, (2010).

Introduction

Inflammatory Bowel Disease (IBD)^1,2 requires close monitoring to detect flare ups early and guide treatment. While endoscopy is the gold standard, it is invasive, costly, and uncomfortable^1,2. Intestinal Ultrasound (IUS) is a non-invasive alternative with strong correlation to endoscopic findings—especially bowel wall thickness (BWT), a marker of disease activity³. Nevertheless, IUS remains limited due to operator dependence and a steep learning curve⁴.
AI has improved consistency in other domains, e.g. endoscopic evaluation, but its application to IUS in IBD remains underexplored. Prior models lack interpretability and require manual image cropping, or are trained on ideal, selected data, limiting clinical use^5,6.

Aims & Methods

We aim to develop a deep-learning model that automatically identifies and paints the bowel wall and measures BWT directly from raw clinical IUS images.
A training dataset of 570 images from 144 IUS videos and a testing dataset of 55 images from 55 separate exams were created. All images were extracted from previously performed IUS examinations reflecting real-world variation, including e.g. unclear boundaries and artefacts.
All images were annotated by International Bowel Ultrasound Group (IBUS) certified experts, including outline-paintings of the inner and outer bowel wall and two BWT measurements.
The AI consists of a combination of Convolutional neural networks and other image processing algorithms.
Evaluation included BWT error against the expert mean, classification accuracy using the standard IBUS 3 mm threshold³, and a leave-one-out comparison with individual doctors.

Results

The model produced predictions on 54 of 55 test images.
The model deviated from the gold standard mean by 0.98 mm (SD 1.1 mm) per image on the regression task. The average distance to expert-defined bounds was 0.44 mm (SD 0.89 mm), with 59% of predictions inside this range.
For classification (using a 3 mm threshold), the model reached an accuracy of 0.77, sensitivity of 0.69, specificity of 0.94, and Cohen’s Kappa of 0.56.
In the leave-one-out analysis, expert performance ranged from 0.89–0.93 accuracy and 0.79–0.83 Kappa. Depending on which expert was excluded from the gold standard, the model achieved 0.74–0.80 accuracy and 0.49–0.60 Kappa. Experts stayed within expert-defined bounds in 72–81% of cases, while the model did so in 46–55%.

Conclusion

Clinically, the model performed well. An error of 0.5–1 mm is negligible in practice and matches typical variation in manual measurements. Many real-world test images had BWT values near the 3 mm threshold, so small deviations led to misclassifications. In practice, a 2.5 mm reading could still raise concerns based on symptoms³.
While the system alone cannot provide expert-level BWT measurements, it could provide assistance to experts as well as non-expert and junior doctors, especially in locating the bowel, which is an essential part of IUS.
The model works on unprocessed clinical data, with the only selection criteria being that there is an identifiable bowel segment, measurable by an IBUS-certified doctor. Allowing the images to reflect realistic conditions
In summary, we developed an AI model that identifies the bowel and measures BWT with acceptable accuracy. We have already started the processes of collecting video data, to extend the AI’s functionality to a fully clinical setting.

References

1. Torres J, Mehandru S, Colombel JF, Peyrin-Biroulet L. Crohn’s disease. The Lancet. 2017;389(10080):1741-1755. doi:10.1016/S0140-6736(16)31711-1
2. Ungaro R, Mehandru S, Allen PB, Peyrin-Biroulet L, Colombel JF. Ulcerative colitis. Lancet. 2017;389(10080):1756-1770. doi:10.1016/S0140-6736(16)32126-2
3. Novak KL, Group I, Nylund K, et al. Expert Consensus on Optimal Acquisition and Development of the International Bowel Ultrasound Segmental Activity Score [IBUS-SAS]: A Reliability and Inter-rater Variability Study on Intestinal Ultrasonography in Crohn’s Disease. J Crohns Colitis. 2021;15(4):609-616. doi:10.1093/ECCO-JCC/JJAA216
4 Bove L, Meyer J, Collins M, Frampas E, Bourreille A, Le Berre C. Understanding the learning curve of intestinal ultrasound in inflammatory bowel disease: A comparative study between novice, regular, and expert. Clin Res Hepatol Gastroenterol. 2025;49(3):102548. doi:10.1016/J.CLINRE.2025.102548
5. Kumaralingam L, Le May K, Dang VB, Alavi J, Huynh HQ, Le LH. Artificial intelligence-assisted approach to assessing bowel wall thickness in pediatric inflammatory bowel disease using intestinal ultrasound images. J Crohns Colitis. 2025;19(4). doi:10.1093/ECCO-JCC/JJAF037
6. Carter D, Albshesh A, Shimon C, et al. Automatized Detection of Crohn’s Disease in Intestinal Ultrasound Using Convolutional Neural Network. Inflamm Bowel Dis. February 2023:1-6. doi:10.1093/IBD/IZAD014

Introduction

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are characterized by dysregulated T-cell responses, causing chronic intestinal inflammation.¹ While anti-TNF therapy is established in IBD, targeting additional pathways may improve outcomes for patients who do not respond adequately to current treatments.² OX40L, an immune co-stimulator, has been implicated in the pathogenesis of several inflammatory conditions.³ Our study provides a comprehensive analysis of the effects of combined TNF and OX40L blockade in a murine adoptive T cell transfer (ATC) model of colitis, examining body weight, detailed histopathological parameters, and a broad range of inflammatory cytokines in colon tissue.

Aims & Methods

Colitis was induced in severe combined immunodeficiency (SCID) mice by intraperitoneal transfer of CD4⁺CD45RB^high T cells isolated from healthy BALB/c donor mice. We established five treatment groups (n=8-10): 1) CD45RB^low transfer “healthy control”, 2) CD45RB^high transfer with isotype antibodies “disease control group”, 3) CD45RB^high transfer with anti-TNF antibody (XT3.11, 250 μg/mouse), 4) CD45RB^high transfer with anti-OX40L antibody (RM134L, 250 μg/mouse), and 5) CD45RB^high transfer with both antibodies at 250 µg/mouse, each. Body weight was monitored for 46 days as a measure of disease progression and normalized to baseline weight at day 1. At study termination, we collected colon tissue for analysis of inflammatory cytokines using multiplex immunoassays and conducted histopathological examination. Histopathological scoring was performed blinded using a validated scoring system for colonic inflammation.⁴

Results

Overall, combined anti-TNF/anti-OX40L therapy was most effective in preventing body weight loss compared to the isotype disease control group, followed by anti-TNF monotherapy and anti-OX40L monotherapy (p<0.0001, p=0.0009, and p=0.03, respectively). Mean normalized body weight (MNBW) of the CD45RB^low healthy control group at termination on day 46 was 115.2 %, while CD45RB^high cell transfer in the disease control group triggered disease induction and body weight loss, with a MNBW of 93.8 % at day 46. The CD45RB^high groups treated with anti-TNF or anti OX40L monotherapy reached a MNBW of 107.6 % and 102.9%, respectively. The CD45RB^high group treated with combination therapy reached 112.6%, closest to the CD45RB^low healthy control group. Notably, only combination therapy led to a significant improvement in histopathological scoring (p=0.0176) compared to the isotype disease control. Similarly, combination treatment consistently resulted in the strongest downregulation of several inflammatory cytokines including IFNg, IL-4, or TNFa, which are increased in colon tissue in the CD45RB^high disease group compared to the CD45RB^low healthy control group.

Conclusion

Combined blockade of TNF and OX40L demonstrated significantly greater efficacy in the ATC preclinical model of IBD in prevention of weight loss, downregulation of key inflammatory cytokines, and reduction of histological damage compared to either monotherapy. These data suggest potential additive efficacy for TNF and OX40L inhibition in controlling intestinal inflammation, and warrant further exploration of dual TNF/OX40L inhibition in clinical trials, particularly among those with inadequate response to anti-TNF monotherapy.

References

1. Kaser A, Zeissig S, Blumberg RS. Inflammatory bowel disease. Annu Rev Immunol. 2010;28:573-621.
2. Vermeire S. Combination biologic therapy for ulcerative colitis. Lancet Gastroenterol Hepatol. 2023;8:288-90.
3. Fu Y, Lin Q, Zhang Z, Zhang L. Therapeutic strategies for the costimulatory molecule OX40 in T-cell-mediated immunity. Acta Pharm Sin B. 2020;10:414-33.
4. Erben U, Loddenkemper C, Doerfel K, Spieckermann S, Haller D, Heimesaat MM, Zeitz M, Siegmund B, Kühl AA. A guide to histomorphological evaluation of intestinal inflammation in mouse models. Int J Clin Exp Pathol. 2014;7:4557-76.

Disclosure

Thomas Leeuw, Rolf Keiffer, Danping Ding-Pfennigdorff, Christian Asbrand, Raaj Mehta, Matthias Herrmann are employees of Sanofi and may hold stock or equity options in Sanofi