Periodic Reporting for period 1 - IMPACT (Imidazole propionate and fibrosis in cardiometabolic diseases)
Okres sprawozdawczy: 2023-08-01 do 2026-01-31
Fibrosis, caused by excessive deposition of extracellular matrix, leads to tissue stiffening, scarring, and loss of organ function. It is a major pathological feature of both heart failure and metabolic dysfunction–associated steatohepatitis (MASH), contributing significantly to morbidity and mortality worldwide. Despite its clinical importance, the mechanisms driving fibrosis remain poorly understood, limiting the development of effective therapies.
Recent research has revealed that gut microbiota and their metabolites play critical roles in cardiometabolic diseases. Building on this concept, our work identified the microbial metabolite imidazole propionate (ImP) as a pathogenic factor in type 2 diabetes, where it impairs insulin signalling via activation of p38γ. More recently, we found that ImP levels are elevated in patients with heart failure and that ImP treatment induces both cardiac and hepatic fibrosis in animal models, implicating the microbiota–ImP–p38γ axis in fibrotic disease development. We also resolved the crystal structure of urocanate reductase (UrdA), the bacterial enzyme responsible for ImP production.
The IMPACT project aims to uncover how microbial metabolites, particularly ImP, contribute to fibrosis and to identify new therapeutic strategies. Specifically, IMPACT will (1) determine how circulating ImP levels correlate with heart and liver fibrosis in humans; (2) investigate how ImP drives fibrotic changes and immune activation in mice; (3) dissect the molecular mechanisms involved; and (4) develop inhibitors of UrdA to block ImP production at its microbial source.
By establishing a mechanistic link between gut microbial metabolism and fibrosis, IMPACT has the potential to transform our understanding and treatment of fibrotic diseases. The project is expected to identify ImP as a biomarker for fibrosis progression, reveal key molecular targets for intervention, and develop microbial enzyme inhibitors with therapeutic potential. These advances could lead to novel, microbiota-targeted approaches for preventing or treating fibrosis in heart failure and MASH—conditions with urgent unmet clinical needs.
Recent research has revealed that gut microbiota and their metabolites play critical roles in cardiometabolic diseases. Building on this concept, our work identified the microbial metabolite imidazole propionate (ImP) as a pathogenic factor in type 2 diabetes, where it impairs insulin signalling via activation of p38γ. More recently, we found that ImP levels are elevated in patients with heart failure and that ImP treatment induces both cardiac and hepatic fibrosis in animal models, implicating the microbiota–ImP–p38γ axis in fibrotic disease development. We also resolved the crystal structure of urocanate reductase (UrdA), the bacterial enzyme responsible for ImP production.
The IMPACT project aims to uncover how microbial metabolites, particularly ImP, contribute to fibrosis and to identify new therapeutic strategies. Specifically, IMPACT will (1) determine how circulating ImP levels correlate with heart and liver fibrosis in humans; (2) investigate how ImP drives fibrotic changes and immune activation in mice; (3) dissect the molecular mechanisms involved; and (4) develop inhibitors of UrdA to block ImP production at its microbial source.
By establishing a mechanistic link between gut microbial metabolism and fibrosis, IMPACT has the potential to transform our understanding and treatment of fibrotic diseases. The project is expected to identify ImP as a biomarker for fibrosis progression, reveal key molecular targets for intervention, and develop microbial enzyme inhibitors with therapeutic potential. These advances could lead to novel, microbiota-targeted approaches for preventing or treating fibrosis in heart failure and MASH—conditions with urgent unmet clinical needs.
WP1 – Cardiac Fibrosis
During the first reporting period, efforts focused primarily on the cardiac effects of imidazole propionate (ImP). Circulating ImP levels were quantified in large cohorts of patients with coronary artery disease (CAD) and heart failure (HF). High ImP concentrations were independently associated with major adverse cardiovascular events (MACE), mortality, and cardiac fibrosis, identifying ImP as a novel prognostic biomarker for cardiovascular risk.
In experimental models, kinetic studies revealed that 8 weeks of ImP treatment induces robust myocardial fibrosis, establishing this as the optimal duration for mechanistic studies. Functional experiments demonstrated that ImP activates cardiac fibroblasts via p38γ-dependent signalling, promoting proliferation and fibrotic remodelling. This mechanism was confirmed in vitro, where a p38γ inhibitor completely blocked ImP-induced fibroblast activation. Preliminary single-cell RNA sequencing identified distinct fibroblast subpopulations emerging after ImP exposure, supporting cellular heterogeneity in the fibrotic response.
Together, these studies provide compelling evidence that the ImP–p38γ axis links gut microbial metabolism to cardiac fibrosis. The findings have generated multiple manuscripts (submitted and published) and form a strong mechanistic basis for subsequent translational studies.
WP2 – Liver Fibrosis
In parallel, the hepatic arm of the project progressed as planned. Preliminary clinical data show a trend toward elevated ImP levels in patients with metabolic dysfunction–associated steatohepatitis (MASH), and cohort expansion is ongoing. Experimental work demonstrated that 8 weeks of ImP exposure similarly induces hepatic fibrosis in western diet–fed mice, mirroring cardiac findings. Transcriptomic profiling experiments are completed, with sequencing analyses pending. These results establish robust conditions for upcoming tissue-specific studies on ImP-driven liver fibrosis.
WP3 – Microbial Inhibitor Development
Significant progress has been made in developing inhibitors of urocanate reductase (UrdA), the bacterial enzyme responsible for ImP synthesis. A nanomolar-range inhibitor was identified and shown to effectively suppress ImP production across several bacterial species expressing functional UrdA. In bioreactor systems modelling the gut microbiota, the inhibitor markedly reduced ImP generation without affecting overall microbial growth, indicating strong selectivity and safety. Preparations are underway to test these inhibitors in vivo.
Summary of Outcomes
After 24 months, IMPACT has:
Identified ImP as an independent biomarker and causal mediator of cardiac fibrosis and cardiovascular events.
Defined the p38γ signalling pathway as central to ImP-induced fibrotic remodelling.
Established 8-week treatment protocols as optimal for fibrosis induction in both cardiac and hepatic models.
Discovered a potent, selective UrdA inhibitor that blocks microbial ImP production in vitro and ex vivo.
Collectively, these results provide the first experimental evidence linking gut microbial metabolism to fibrotic disease and lay the groundwork for microbiome-targeted therapeutic strategies in heart failure and MASH.
During the first reporting period, efforts focused primarily on the cardiac effects of imidazole propionate (ImP). Circulating ImP levels were quantified in large cohorts of patients with coronary artery disease (CAD) and heart failure (HF). High ImP concentrations were independently associated with major adverse cardiovascular events (MACE), mortality, and cardiac fibrosis, identifying ImP as a novel prognostic biomarker for cardiovascular risk.
In experimental models, kinetic studies revealed that 8 weeks of ImP treatment induces robust myocardial fibrosis, establishing this as the optimal duration for mechanistic studies. Functional experiments demonstrated that ImP activates cardiac fibroblasts via p38γ-dependent signalling, promoting proliferation and fibrotic remodelling. This mechanism was confirmed in vitro, where a p38γ inhibitor completely blocked ImP-induced fibroblast activation. Preliminary single-cell RNA sequencing identified distinct fibroblast subpopulations emerging after ImP exposure, supporting cellular heterogeneity in the fibrotic response.
Together, these studies provide compelling evidence that the ImP–p38γ axis links gut microbial metabolism to cardiac fibrosis. The findings have generated multiple manuscripts (submitted and published) and form a strong mechanistic basis for subsequent translational studies.
WP2 – Liver Fibrosis
In parallel, the hepatic arm of the project progressed as planned. Preliminary clinical data show a trend toward elevated ImP levels in patients with metabolic dysfunction–associated steatohepatitis (MASH), and cohort expansion is ongoing. Experimental work demonstrated that 8 weeks of ImP exposure similarly induces hepatic fibrosis in western diet–fed mice, mirroring cardiac findings. Transcriptomic profiling experiments are completed, with sequencing analyses pending. These results establish robust conditions for upcoming tissue-specific studies on ImP-driven liver fibrosis.
WP3 – Microbial Inhibitor Development
Significant progress has been made in developing inhibitors of urocanate reductase (UrdA), the bacterial enzyme responsible for ImP synthesis. A nanomolar-range inhibitor was identified and shown to effectively suppress ImP production across several bacterial species expressing functional UrdA. In bioreactor systems modelling the gut microbiota, the inhibitor markedly reduced ImP generation without affecting overall microbial growth, indicating strong selectivity and safety. Preparations are underway to test these inhibitors in vivo.
Summary of Outcomes
After 24 months, IMPACT has:
Identified ImP as an independent biomarker and causal mediator of cardiac fibrosis and cardiovascular events.
Defined the p38γ signalling pathway as central to ImP-induced fibrotic remodelling.
Established 8-week treatment protocols as optimal for fibrosis induction in both cardiac and hepatic models.
Discovered a potent, selective UrdA inhibitor that blocks microbial ImP production in vitro and ex vivo.
Collectively, these results provide the first experimental evidence linking gut microbial metabolism to fibrotic disease and lay the groundwork for microbiome-targeted therapeutic strategies in heart failure and MASH.
The results indicate that ImP could be both a marker and target of fibrotic diseases in both the heart and liver. To further elaborate on this we would need to define normal values for use as biomarker and further investigate how levels of the metabolite predicts risk of disease. Second, our work on identifying and developing inhibitors holds promise to develop a treatment based on inhibiting UrdA.