Introduction

Irritable Bowel Syndrome (IBS) is a prevalent and chronic gastrointestinal disorder that affects approximately 85 million Europeans. It predominantly impacts women and significantly impairs quality of life, presenting with recurrent abdominal pain and altered bowel habits in the absence of identifiable structural abnormalities. Beyond its gastrointestinal symptoms, IBS frequently co-occurs with mental and somatic conditions such as anxiety, depression, fibromyalgia (32.5%), and chronic fatigue syndrome (14%). Up to 60% of IBS patients experience mental comorbidities, highlighting the complex interplay between gut and brain—often referred to as dysregulation of the gut–brain axis. This dysregulation manifests in altered intestinal motility, increased gut permeability, visceral hypersensitivity, and significant shifts in gut microbiota composition.

Aims & Methods

We present the DISCOVERIE project (Development, dIagnostic and prevention of gender-related Somatic and mental COmorbitiEs in iRritable bowel syndrome In Europe), an international, multi-centre initiative aimed at characterizing IBS and its associated comorbidities, with a particular focus on sex- and gender-related differences. To this end, we generated a comprehensive multi-omics dataset from 743 individuals, including shotgun quantitative microbiome profiling and untargeted metabolomics. These molecular data were complemented by in-depth clinical phenotyping, capturing information on anxiety, depression, fibromyalgia, and chronic fatigue syndrome. Particular attention was given to age, sex/gender, lifestyle factors, and systemic inflammatory markers. Multivariate statistical models were applied, correcting for common microbiome confounders, to analyze the multi-omics layers and identify microbiome-related signatures and mechanistic links across IBS and its comorbid subgroups.

Results

Our microbiome analysis revealed that IBS subjects exhibit features of a dysbiotic bacterial community, characterized by an increased prevalence of the Bacteroides 2 enterotype (17–26% in IBS participants across comorbid groups vs. 17% in the general population and only 2% in the healthy control group; chi-squared test, FDR < 0.05), a reduced butyrate synthesis capacity, and increased levels of opportunistic taxa compared to non-IBS controls.
Interestingly, IBS individuals—regardless of comorbidities—showed enrichment of bacterial metabolic modules involved in the degradation of amino acids that serve as precursors for neurotransmitters. Specifically, we observed an increase in pathways associated with GABA degradation and a decrease in modules responsible for glutamate biosynthesis. This dysregulation of gut neurotransmitter metabolism may contribute to hallmark IBS symptoms.
Strikingly, pro-inflammatory IL-6 levels were strongly associated with specific bacterial genus (FDR < 0.05), as well as with a metabolic module responsible for the degradation of gamma-hydroxybutyric acid (GHB), a neurotransmitter and central nervous system depressant, suggesting a potential mechanistic link between low-grade inflammation and depressive symptoms in IBS.

Conclusion

The results from this large-scale, multi-center international study reveal a dysregulation of gut neurotransmitter metabolism that may contribute to IBS symptoms and associated comorbidities. These findings underscore a potential link between elevated IL-6 levels, microbial metabolism, and the gut–brain axis, offering new insights into the complex interplay between microbiota composition, host physiology, and IBS-related comorbidities.

Introduction

Immune checkpoint inhibitors (ICIs) have marked a breakthrough in the management of a wide range of cancer types, leading to increased overall survival. However, this treatment is frequently associated with the onset of various immune-related adverse events (irAEs), including ICI-related diarrhea and colitis.¹ Current recommendations for patients with diarrhea or colitis grade 2 or higher (graded via CTCAE)² include the discontinuation of ICI and administration of immune suppressants (e.g. steroids or biologics), which may lead to worse outcomes in these patients.³ Therefore, alternative therapeutic strategies to manage irAEs are needed. The gut microbiota plays a pivotal role in the onset of gastrointestinal irAEs, but the role of its therapeutic modulation on these disorders is mostly unknown. ^4,5

Aims & Methods

Our aim was to evaluate the efficacy and safety of therapeutic microbiome modulation for gastrointestinal irAEs in cancer patients. We enrolled cancer patients affected by ICI-related diarrhea/colitis referred to our Microbiome Clinic from January 2023 to March 2025. After clinical evaluation, patients were stratified according to severity of diarrhea (graded via CTCAE)² and then received a microbiome-modulating therapy. Patients were followed-up for at least 8 week after the initiation of therapy. We collected data about patient demographics (age and gender), patient’s overall health status as assessed by the the Charlson Comorbidity Index (CCI)⁶, type of cancer, oncological therapy and its suspension, time in weeks from initiation of cancer therapy to onset of diarrhea, severity of diarrhea (graded via CTCAE)², time in weeks until resolution of diarrhea and resumption of oncological therapy

Results

We enrolled 42 patients in the study period (8 males, 34 females, mean age 58,3 years-old, mean CCI-index 5.8). All patients were treated with ICI (Pembrolizumab: n=25 , Dostarlimab: n=4, Nivolumab: n=4; Atezolizumab: n=3; Novulumab and Ipilumab: n=2, Cemiplimab: n=2; Mogamulizumab: n=1; Pertuzumab: n=1). Ten patients experienced G1 diarrhea (23,8%), 16 (38,1) G2, 15 (35,7%) G3 and one G4 (2,4%). As indicated by current European Guidelines³, 30 patients (71,4%) had to interrupt ICI due to diarrhea. Multi-strain probiotics were administered to 27 (64.3% ) patients, rifaximin to 22 (52,4%). Overall, 21 patients (50%) needed therapy with systemic steroids. Seven patients who experienced ICI-related colitis refractory to steroids and biologics were successfully treated with FMT. Twenty-eight patients (66.7% ) had a resolution of the diarrhea (G0) and 11 patients (26.2%) had diarrhea G1 at a mean time of 8 weeks. Upon resolution of diarrhea, nine of the 30 patients who had interrupted ICI (30%) were able to resume the treatment. None of the patients experienced any adverse event related to gut microbiota modulation as defined by CTCAE².

Conclusion

Therapeutic modulation of gut microbiota appears to be a promising safe and effective approach for treating ICI-related diarrhea and colitis. However, these preliminary findings need confirmation through more consolidated and well-designed studies.

References

1. Dougan M, Wang Y, Rubio-Tapia A, Lim JK. AGA Clinical Practice Update on Diagnosis and Management of Immune Checkpoint Inhibitor Colitis and Hepatitis: Expert Review. Gastroenterology. 2021;160(4):1384-1393. doi:10.1053/j.gastro.2020.08.063
2. Freites-Martinez A, Santana N, Arias-Santiago S, Viera A. Using the Common Terminology Criteria for Adverse Events (CTCAE - Version 5.0) to Evaluate the Severity of Adverse Events of Anticancer Therapies. Actas Dermosifiliogr. 2021;112(1):90-92. doi:10.1016/j.ad.2019.05.009
3. Haanen J, Obeid M, Spain L, et al. Management of toxicities from immunotherapy: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Ann Oncol. 2022;33(12):1217-1238. doi:10.1016/j.annonc.2022.10.001
4. Wang Y, Wiesnoski DH, Helmink BA, et al. Fecal microbiota transplantation for refractory immune checkpoint inhibitor-associated colitis. Nat Med. 2018;24(12):1804-1808. doi:10.1038/s41591-018-0238-9
5. Wang T, Zheng N, Luo Q, et al. Probiotics Lactobacillus reuteri Abrogates Immune Checkpoint Blockade-Associated Colitis by Inhibiting Group 3 Innate Lymphoid Cells. Front Immunol. 2019;10. doi:10.3389/fimmu.2019.01235
6. Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: Development and validation. J Chronic Dis. 1987;40(5):373-383. doi:10.1016/0021-9681(87)90171-8

Disclosure

G.I. has received personal fees for acting as speaker for Biocodex, Danone, Sofar, Malesci, Metagenics and Tillotts Pharma, and for acting as consultant and/or advisor for Ferring Therapeutics, Giuliani, Malesci and Tillotts Pharma. A.G. reports personal fees for consultancy from Eisai Srl, 3PSolutions, Real Time Meeting, Fondazione Istituto Danone, SinergieSrl, Board MRGE and Sanofi SpA personal fees for acting as a speaker for Takeda SpA, AbbVie and Sandoz SpA and personal fees for acting on advisory boards for VSL3 and Eisai. G.C. has received personal fees for acting as advisor for Ferring Therapeutics. All other authors have no conflicts of interest to disclose.

Introduction

Portal hypertension (PHT) most commonly due to cirrhosis, but non-cirrhotic portal hypertension (NCPH) related to metabolic dysfunction, specifically metabolic dysfunction-associated steatotic liver disease (MASLD), necessitates further clarification of its mechanisms and identification of therapeutic targets.

PHT may precede the development of hepatic fibrosis in MASLD, and even serve as a driving factor in the pathogenesis of MASLD. Consequently, metabolic dysfunction-associated PHT might not depend on structural alterations such as hepatic fibrosis or pseudolobule formation, but rather correlate with other factors such as endothelial dysfunction, which has been demonstrated to play a pivotal role in NCPH. Endothelial dysfunction encompasses endothelial injury and endothelial-to-mesenchymal transition (EndMT), the latter being a specific type of epithelial-to-mesenchymal transition (EMT). As reported, the JAK/STAT3 signaling pathway plays a pivotal role in the initiation and progression of EMT. Similarly, patients with NCPH induced by myeloproliferative neoplasms (MPN) often lack pathological features such as hepatic fibrosis or pseudolobule formation. The Janus kinase 2 (JAK2) V617F mutation is highly prevalent in MPN patients. Therefore, targeted inhibition of JAK2 serves as an effective therapeutic strategy for MPN.

Given the shared pathological features between MPN-associated portal hypertension and MASLD-associated portal hypertension, as well as the vital​ role of JAK2 in both disease, the application of JAK2 inhibitor holds significant therapeutic potential for metabolic dysfunction-associated portal hypertension.

Aims & Methods

This study aims to verify the therapeutic efficacy of JAK2 inhibition in attenuating MASLD-associated PHT, with particular focus on its modulation of EndMT. Mice were fed with a high-fat diet (HFD) diet for 12 weeks to induce MASLD-associated PHT and divided into two groups, the treatment group (Rux) and control (Ctr) group. Ruxolitinib (JAK2 inhibitor) was given as a suspension by gavage (60 mg/kg in 0.2 ml) every two days for 3 weeks, while controls received the same volume of saline, from week 10-12 of feeding. Portal pressure was measured, serological analysis and histopathological staining were performed. RT-PCR and Western Blot were conducted to measure EndMT-related genes expression.

Results

The treatment group (Rux) demonstrated a significant reduction in directly measured portal pressure, with concordant changes observed in the spleen-to-body weight ratio, which served as an indirect indicator of portal pressure. Concurrent improvement was noted in ALT, AST and TC. H&E, Masson and Sirius red staining showed decreased perisinusoidal and perivascular fibrosis in the Rux group. Electron microscopy revealed restoration of endothelial fenestration. Additionally, ruxolitinib treatment led to downregulation of endothelial damage markers, mesenchymal cell markers as well as EndMT-related regulatory factors, indicating an alleviation of EndMT and endothelial dysfunction.

Conclusion

The JAK2 inhibitor demonstrates therapeutic potential for MASLD-associated PHT through modulation of endothelial dysfunction and EndMT. These mechanistic insights position ruxolitinib as a promising candidate for clinical management of NCPH, particularly in the MASLD-associated PHT.

References

[1] European Association for the Study of the Liver; European Association for the Study of Diabetes; European Association for the Study of Obesity. EASL-EASD-EASO Clinical Practice Guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD): Executive Summary. Diabetologia. 2024 Jun 13. [2] Song Z, Liu X, Zhang W, et al. Ruxolitinib suppresses liver fibrosis progression and accelerates fibrosis reversal via selectively targeting Janus kinase 1/2. Journal of Translational Medicine. 2022, 20(1): 157.
[3] Zhang XL, Zhang XY, Ge XQ, et al. Mangiferin prevents hepatocyte epithelial-mesenchymal transition in liver fibrosis via targeting HSP27-mediated JAK2/STAT3 and TGF-β1/Smad pathway. Phytotherapy Research. 2022, 36(11): 4167-4182.
[4] Jin W. Role of JAK/STAT3 Signaling in the Regulation of Metastasis, the Transition of Cancer Stem Cells, and Chemoresistance of Cancer by Epithelial-Mesenchymal Transition. Cells. 2020;9(1):217.
[5] Hammoutene A, Rautou PE. Role of liver sinusoidal endothelial cells in non-alcoholic fatty liver disease. Journal of Hepatology. 2019, 70(6): 1278–1291.