Periodic Reporting for period 1 - INFLEMT (Functional role of Epithelial–to–Mesenchymal Transition in the pathogenesis of Inflammatory Bowel Disease)
Période du rapport: 2021-07-01 au 2023-06-30
The INFLEMT project aims to address the functional role of the process termed Epithelial–to–Mesenchymal Transition (EMT) in the pathogenesis of Inflammatory Bowel Disease (IBD).
IBD (with its two major manifestations: ulcerative colitis and Crohn’s disease) defines a group of chronic inflammatory disorders of the digestive tract representing a chronic idiopathic disease affecting 2.5 million people in Europe, with considerable costs for the health care system. Loss of work productivity and reduced quality of life are estimated to account for even higher costs than those associated with hospitalization, treatments and surgery.
Compromised barrier functionality, chronic inflammation and persistent injury of the intestinal mucosa represent central drivers of IBD. This chronic tissue damage, with its recurring cycles of inflammation, remission and flare ups, triggers the development of intestinal fibrosis which is responsible for common IBD complications such as strictures and fistulae, all requiring surgical intervention. The global rise of IBD prevalence together with the challenges associated with the development of complications and the unresponsiveness to the new biological therapies are posing an urgent need to better understand the mechanisms underpinning IBD pathogenesis.
The term EMT defines is a cellular trans-differentiation program by which epithelial cells lose their identity and acquire phenotypic and functional features typical of fibroblasts. EMT has been recently shown to represent an epithelial injury-induced damage response impairing cell functionality and regenerative capacity, and to be a fuel of fibrosis by modulating the immune response.
The process of EMT has been implicated in the pathogenesis of IBD, but its precise functional role is currently unknown.
The overall objective of the INFLEMT project was to determine the functional consequences the activation of the EMT program has in terms of epithelial injury response and modulation of inflammation and fibrogenic, pursuing the central hypothesis that EMT is a major functional driver in the pathogenesis of IBD.
Specific objectives were the following:
1. Profile EMT in human IBD.
2. Elucidate the functional impact of EMT on the integrity and functionality of the intestinal epithelial barrier.
3. Explore the effects of EMT on the development of fibrosis and modulation of the immune cell response.
The ultimate goal of INFLEMT was to provide a novel understanding of the epithelial-driven mechanisms supporting persistent damage and inflammation, which could allow to design innovative approaches to protect the intestinal mucosa in IBD patients. Since Europe has the highest global IBD prevalence, INFLEMT provides novel insights into the pathogenesis of a disease having a huge socio-economic impact in Europe.
IBD (with its two major manifestations: ulcerative colitis and Crohn’s disease) defines a group of chronic inflammatory disorders of the digestive tract representing a chronic idiopathic disease affecting 2.5 million people in Europe, with considerable costs for the health care system. Loss of work productivity and reduced quality of life are estimated to account for even higher costs than those associated with hospitalization, treatments and surgery.
Compromised barrier functionality, chronic inflammation and persistent injury of the intestinal mucosa represent central drivers of IBD. This chronic tissue damage, with its recurring cycles of inflammation, remission and flare ups, triggers the development of intestinal fibrosis which is responsible for common IBD complications such as strictures and fistulae, all requiring surgical intervention. The global rise of IBD prevalence together with the challenges associated with the development of complications and the unresponsiveness to the new biological therapies are posing an urgent need to better understand the mechanisms underpinning IBD pathogenesis.
The term EMT defines is a cellular trans-differentiation program by which epithelial cells lose their identity and acquire phenotypic and functional features typical of fibroblasts. EMT has been recently shown to represent an epithelial injury-induced damage response impairing cell functionality and regenerative capacity, and to be a fuel of fibrosis by modulating the immune response.
The process of EMT has been implicated in the pathogenesis of IBD, but its precise functional role is currently unknown.
The overall objective of the INFLEMT project was to determine the functional consequences the activation of the EMT program has in terms of epithelial injury response and modulation of inflammation and fibrogenic, pursuing the central hypothesis that EMT is a major functional driver in the pathogenesis of IBD.
Specific objectives were the following:
1. Profile EMT in human IBD.
2. Elucidate the functional impact of EMT on the integrity and functionality of the intestinal epithelial barrier.
3. Explore the effects of EMT on the development of fibrosis and modulation of the immune cell response.
The ultimate goal of INFLEMT was to provide a novel understanding of the epithelial-driven mechanisms supporting persistent damage and inflammation, which could allow to design innovative approaches to protect the intestinal mucosa in IBD patients. Since Europe has the highest global IBD prevalence, INFLEMT provides novel insights into the pathogenesis of a disease having a huge socio-economic impact in Europe.
Novel mouse models to conditionally delete EMT in intestinal epithelial cells were generated and confirmed to be born according to the expected mendelian inheritance, therefore indicating that EMT is dispensable during intestinal embryonic development. Mice were observed up to one year of age and confirmed to be healthy and not displaying any overt phenotype. A conditional lineage-tracing tdTomato allele was successfully included in the colony in order to fate map the intestinal epithelium. Fidelity of this intestinal system was confirmed and successful deletion of the EMT transcription factors was proved.
These WT and EMT-cKO mice were subjected to experimental models of both acute and chronic colitis and comprehensive recording of the clinical signs of colitis was performed, as well as histological analysis. EMT-cKO revealed alterations in the colitic phenotype, evident especially in the regenerative phase after induction of the injury. Moreover they displayed a differential integrity of the intestinal barrier compared to the WT mice observed in an in vivo permeability assay. Time course analysis of damage-regeneration phases and EMT induction were also included to temporally map the activation of EMT, and to define the underlying molecular mechanisms by RNAseq.
In a closely related collaborative project, where the expertise matured during the INFLEMT project was instrumental, we discovered a mechanical basis for the involvement of EMT in the generation of another IBD complication, called perianal fistula, consisting in the formation of tunnel-like structures in the intestinal wall which require surgical intervention. In fact, the dysfunctional extracellular matrix composition observed in the fistula triggers the EMT process through the activation of mechano-sensitive proteins. EMT activation in this context has been shown to be the driver mechanisms of the formation of this tunnel-like structures. The finding of a mechano-regulated induction of EMT has important implications in terms of therapy design, indicating that the use of anti-inflammatory medications must be integrated with the use of therapeutic strategies targeting the tissue mechanical properties.
These WT and EMT-cKO mice were subjected to experimental models of both acute and chronic colitis and comprehensive recording of the clinical signs of colitis was performed, as well as histological analysis. EMT-cKO revealed alterations in the colitic phenotype, evident especially in the regenerative phase after induction of the injury. Moreover they displayed a differential integrity of the intestinal barrier compared to the WT mice observed in an in vivo permeability assay. Time course analysis of damage-regeneration phases and EMT induction were also included to temporally map the activation of EMT, and to define the underlying molecular mechanisms by RNAseq.
In a closely related collaborative project, where the expertise matured during the INFLEMT project was instrumental, we discovered a mechanical basis for the involvement of EMT in the generation of another IBD complication, called perianal fistula, consisting in the formation of tunnel-like structures in the intestinal wall which require surgical intervention. In fact, the dysfunctional extracellular matrix composition observed in the fistula triggers the EMT process through the activation of mechano-sensitive proteins. EMT activation in this context has been shown to be the driver mechanisms of the formation of this tunnel-like structures. The finding of a mechano-regulated induction of EMT has important implications in terms of therapy design, indicating that the use of anti-inflammatory medications must be integrated with the use of therapeutic strategies targeting the tissue mechanical properties.
The global rise of IBD prevalence, especially in European countries, the challenges associated with the development of complications such as fibrosis, and the significant unresponsiveness to the novel biological therapies clearly demonstrate that there is an urgent need to gain a deeper understanding of the mechanisms underpinning IBD pathogenesis. The INFLEMT project contributes to this mission, investigating a cellular process affecting the injured intestinal epithelium and providing a novel functional perspective in its contribution to this disease. Moreover, it opens to the possibility that this cellular process could be implicated in other types of injuries inflicted to the intestinal mucosa, such as radiation- and immunecheckpoint blockade-induced acute and chronic colitis which affect oncological patients. Therefore, the findings of the INFLEMT project have the potential to be additionally exploited to other types of intestinal diseases.