Despite delays caused by COVID-19, the consortium successfully recruited more tha 800 participants—including IBS patients with and without comorbidities, disease controls, and healthy controls—exceeding initial recruitment targets. Demographic analyses revealed a higher prevalence of females in comorbid groups and increased use of antidepressants among multicomorbid patients. Questionnaire’s data indicated a progressive increase in somatic and psychological symptom severity correlating with the number of comorbidities. Biological sample collection protocols were standardized; samples (blood, feces, urine, colonic biopsies) were collected, stored, and shipped for analysis. Initial assessments of intestinal permeability via LMS test in urine samples did not show group differences, although ex vivo studies on colonic biopsies indicated a trend toward reduced transepithelial electrical resistance, suggesting increased permeability in IBS patients. Additionally, two animal models explored brain–gut bidirectional influences, with results highlighting alterations in epithelial and blood-brain barrier permeability, neuroinflammation, and anxiety behaviors.
Neurophysiological assessments involved stress induction via the Montreal Imaging Stress Test and daily life stress via the Maastricht Acute Stress Task. While neural activation patterns did not significantly differ between groups, patients with comorbidities reported higher negative affect and exhibited exaggerated cortisol responses to stress, although these measures lacked sufficient specificity as biomarkers. Preclinical gut-to-brain models demonstrated that early-life epithelial barrier disruptions contributed to neuroinflammation and anxiety, with microbiota transfers from IBS donors inducing visceral hypersensitivity and sex-specific stress axis alterations. Metagenomic and metabolomic analyses of fecal samples revealed microbial dysbiosis characterized by increased Bacteroides 2 enterotype prevalence, decreased butyrate-producing bacteria, and altered microbial metabolites, such as tiropramide and glutarate. Microbial immune markers linked dysbiosis to immune activation and gut-brain interactions. Genetic and epigenetic investigations identified overlapping loci between IBS and mental health disorders, indicating complex regulatory mechanisms. The project achieved validation of biomarker signatures capable of differentiating IBS subtypes and comorbidity profiles. The fully developed ELISA assay has been validated and is commercially available, providing a tool for clinical research. Additional immunoassays for markers have been tested, and point-of-care lateral flow formats are under exploration to facilitate rapid diagnostics. Development of assays suitable for preclinical models is progressing, enabling translational research bridging human findings with mechanistic animal studies. Digital health platforms have been employed to monitor symptom triggers and patient phenotypes in real-time. ESM-based PROM studies identified associations between psychosocial factors, environmental triggers, and symptom fluctuations, revealing significant heterogeneity across patients. The Vitalera platform collected activity, sleep, and physiological data via Fitbit devices; analyses showed minor differences between patients with and without comorbidities, with subjective symptom burden and mental health scores more strongly associated with multi-morbidity than objective metrics. Longitudinal data suggest stability in physical activity and sleep patterns, emphasizing the importance of integrating subjective reports to capture disease heterogeneity. Finally, the project delivered recommendations on clinical guidelines focusing on sex- and age-specific management strategies aimed at improving patient outcomes and quality of life. The project’s strategic dissemination activities include open-access publications, a dedicated website (
https://discoverie.eu/(s’ouvre dans une nouvelle fenêtre)) newsletters, social media channels, stakeholder seminars, and an exploitation plan with the establishment of an Innovation and Exploitation Advisory Panel. Despite pandemic-related delays, the project successfully completed recruitment, biological sample collection, and cross -WP analyses, laying a solid foundation for future translational applications.
