Periodic Reporting for period 3 - INVADERS (Mucus-Penetrating Microbiota: Characterization, Mechanism and Therapeutic in Metabolic Disease)
Reporting period: 2022-10-01 to 2024-03-31
Humanity is facing an epidemic of inter-related metabolic disorders, including obesity, insulin resistance, hyperglycemia, hyperlipidemia, and hepatic steatosis, that altogether have major impact on the promotion of cardiovascular diseases. The increasing incidence of these complex metabolic disorders and their highly morbid, chronic and costly downstream diseases threatens to overwhelm the world’s health care systems and economies, making it a top public health priority in dire need of investigation.
The intestinal tract is inhabited by a large and diverse community of bacteria, collectively referred to as the intestinal microbiota. When stably maintained at an appropriately safe distance from the epithelial cell monolayer, the microbiota provides important benefits to its host. However, disturbance of the microbiota-host relationship, promoted by genetic or non-genetic factors, can alter intestinal homeostasis and drive chronic low-grade intestinal inflammation, ultimately leading to metabolic abnormalities. We previously reported that a ubiquitous class of food additives, emulsifiers, detrimentally impact the microbiota resulting in its encroachment into the mucus layer that associated with low-grade inflammation and development of metabolic disorders.
The central goal of this proposal is to investigate the hypothesis that bacteria that penetrate the inner part of the mucus layer, referred as invaders, promote development of metabolic alterations.
We herein propose to identify mucus-invaders, in preclinical models and clinical conditions, and investigate mechanisms by which they promote inflammatory and metabolic abnormalities. Furthermore, we propose to define original approaches to modulate the intestinal microbiota in order to counteract microbiota encroachment and protect against associated metabolic abnormalities.
The intestinal tract is inhabited by a large and diverse community of bacteria, collectively referred to as the intestinal microbiota. When stably maintained at an appropriately safe distance from the epithelial cell monolayer, the microbiota provides important benefits to its host. However, disturbance of the microbiota-host relationship, promoted by genetic or non-genetic factors, can alter intestinal homeostasis and drive chronic low-grade intestinal inflammation, ultimately leading to metabolic abnormalities. We previously reported that a ubiquitous class of food additives, emulsifiers, detrimentally impact the microbiota resulting in its encroachment into the mucus layer that associated with low-grade inflammation and development of metabolic disorders.
The central goal of this proposal is to investigate the hypothesis that bacteria that penetrate the inner part of the mucus layer, referred as invaders, promote development of metabolic alterations.
We herein propose to identify mucus-invaders, in preclinical models and clinical conditions, and investigate mechanisms by which they promote inflammatory and metabolic abnormalities. Furthermore, we propose to define original approaches to modulate the intestinal microbiota in order to counteract microbiota encroachment and protect against associated metabolic abnormalities.
During the first half of this project, significant progresses were made on all of the proposed scientific aims.
Aim 1. Identify microbiota invaders of the mucus layer and investigate their ability to promotes metabolic disorders. We and others have previously demonstrated that microbiota encroachment and hte presence of invaders within the normally sterile inner mucus layer lining the gastro-intestinal tract is associated with the development of chronic inflammatory diseases, in both pre-clinical models and in humans. However, the identity of mucus invaders, as well as the extent to which they can directly promote chronic inflammatory diseases both remained unknown when this INVADERS project started. During the first half of this project, we
- Examined the extent to which dietary emulsifiers directly impact a series of human microbiotas ex vivo, allowing us to define consistent patterns of alteration in microbiotas from healthy hosts and patients at various metabolic disease stages. Such approaches allowed us to identified resistant and susceptible microbiota to disturbance, and the molecular drivers are currently being identified.
- Used laser capture microdissection to isolate and identify mucus-infiltrating bacteria in various conditions and using both pre-clinical and human-derived samples. Such approaches allowed us to identified, for the first time, invaders identity that we are now planning test for their ability to promote inflammation and metabolic disorders upon transfer to new hosts.
Aim 2. Develop approaches to exclude bacteria from the inner mucus layer and thus protect against metabolic disorders. Our hypothesis here is that mucus-penetrating bacteria play a central role in driving metabolic disorders holds that prevention of microbiota encroachment will protect against metabolic disorders that resulted from a variety of initiating causes. During the first half of this project, we
- investigated the ability of probiotic Akkermansia muciniphila (Akm) to protect against microbiota encroachment and associated detrimental consequences. The impact of Akm on host and microbiota were investigated, leading to a work recently published in Gut.
- Investigated the ability of flagellin-targeted immunization to drive mucosal anti-flagellin antibodies, decrease bacterial encroachment and protect against dietary emulsifier-induced metabolic abnormalities. We observed that such immunization protects against emulsifier-induced metabolic disorders and alters microbiota composition and/or gene expression. While these initial findings are currently being prepared for submission for publication, mechanistic investigations are ongoing in order to better understand anti-flagellin immunization impact on the host-microbiota interaction at the mucosal surface.
Aim 3. Examine metabolic disease- and emulsifier consumption-associated mucus-penetrating bacteria in humans. While tractable mouse models provide a powerful platform of discovery and mechanistic investigation, it is essential that conclusions obtained from such models be proven relevant to human health and diseases. We for exemple previously demonstrated that microbiota encroachment is a feature of metabolic disorders in humans. During the first half of this project, we
- obtained all authorizations needed for these clinical work. Future years of this research will now identify, in these samples, mucus associated bacteria as well as test their ability to drive chronic intestinal inflammation and associated metabolic deregulations.
Aim 1. Identify microbiota invaders of the mucus layer and investigate their ability to promotes metabolic disorders. We and others have previously demonstrated that microbiota encroachment and hte presence of invaders within the normally sterile inner mucus layer lining the gastro-intestinal tract is associated with the development of chronic inflammatory diseases, in both pre-clinical models and in humans. However, the identity of mucus invaders, as well as the extent to which they can directly promote chronic inflammatory diseases both remained unknown when this INVADERS project started. During the first half of this project, we
- Examined the extent to which dietary emulsifiers directly impact a series of human microbiotas ex vivo, allowing us to define consistent patterns of alteration in microbiotas from healthy hosts and patients at various metabolic disease stages. Such approaches allowed us to identified resistant and susceptible microbiota to disturbance, and the molecular drivers are currently being identified.
- Used laser capture microdissection to isolate and identify mucus-infiltrating bacteria in various conditions and using both pre-clinical and human-derived samples. Such approaches allowed us to identified, for the first time, invaders identity that we are now planning test for their ability to promote inflammation and metabolic disorders upon transfer to new hosts.
Aim 2. Develop approaches to exclude bacteria from the inner mucus layer and thus protect against metabolic disorders. Our hypothesis here is that mucus-penetrating bacteria play a central role in driving metabolic disorders holds that prevention of microbiota encroachment will protect against metabolic disorders that resulted from a variety of initiating causes. During the first half of this project, we
- investigated the ability of probiotic Akkermansia muciniphila (Akm) to protect against microbiota encroachment and associated detrimental consequences. The impact of Akm on host and microbiota were investigated, leading to a work recently published in Gut.
- Investigated the ability of flagellin-targeted immunization to drive mucosal anti-flagellin antibodies, decrease bacterial encroachment and protect against dietary emulsifier-induced metabolic abnormalities. We observed that such immunization protects against emulsifier-induced metabolic disorders and alters microbiota composition and/or gene expression. While these initial findings are currently being prepared for submission for publication, mechanistic investigations are ongoing in order to better understand anti-flagellin immunization impact on the host-microbiota interaction at the mucosal surface.
Aim 3. Examine metabolic disease- and emulsifier consumption-associated mucus-penetrating bacteria in humans. While tractable mouse models provide a powerful platform of discovery and mechanistic investigation, it is essential that conclusions obtained from such models be proven relevant to human health and diseases. We for exemple previously demonstrated that microbiota encroachment is a feature of metabolic disorders in humans. During the first half of this project, we
- obtained all authorizations needed for these clinical work. Future years of this research will now identify, in these samples, mucus associated bacteria as well as test their ability to drive chronic intestinal inflammation and associated metabolic deregulations.
By the end of the project, we expect the following progresses to be made.
Aim 1. Identify microbiota invaders of the mucus layer and investigate their ability to promotes metabolic disorders. This aim will yield the identities of specific species and/or classes of bacteria, present in many humans, that are enriched by direct exposure of microbiotas to emulsifiers. Moreover, we anticipate that some of these enriched species will penetrate the mucus to encroach upon host epithelial cells, possibly in a manner facilitated by direct effects that emulsifiers may have on mucus integrity. Lastly my hypothesis predicts that such mucus-penetrating bacterial will exhibit an inherently increased capacity to promote inflammation that will manifest as obesity and/or its associated metabolic disorders in mice transplanted with such bacteria.
Aim 2. Develop approaches to exclude bacteria from the inner mucus layer and thus protect against metabolic disorders. Here, we expect that both Akkermansia muciniphila supplementation and flagellin immunization will promote a healthy stable host-microbiota relationship by keeping the intestinal microbiota at a safe distance and may offer protection against emulsifier-induced metabolic alterations.
Aim 3. Examine metabolic disease- and emulsifier consumption-associated mucus-penetrating bacteria in humans. Here, we predict that we will confirm an altered microbiota localization in the mucosa of patients with metabolic abnormalities, associated with enrichment of select bacteria members. We predict that there will be bacterial members that positively correlate with the severity of metabolic alterations, supporting the notion that mucus-infiltrating microbiota plays a direct role in promoting metabolic alterations. The isolation of invaders will also enable to identify human-derived bacteria able to confer metabolic alterations, and we predict that encroached bacteria isolated from patients with metabolic disorders will have the ability to instigate inflammation, obesity and associated metabolic disorders.
Aim 1. Identify microbiota invaders of the mucus layer and investigate their ability to promotes metabolic disorders. This aim will yield the identities of specific species and/or classes of bacteria, present in many humans, that are enriched by direct exposure of microbiotas to emulsifiers. Moreover, we anticipate that some of these enriched species will penetrate the mucus to encroach upon host epithelial cells, possibly in a manner facilitated by direct effects that emulsifiers may have on mucus integrity. Lastly my hypothesis predicts that such mucus-penetrating bacterial will exhibit an inherently increased capacity to promote inflammation that will manifest as obesity and/or its associated metabolic disorders in mice transplanted with such bacteria.
Aim 2. Develop approaches to exclude bacteria from the inner mucus layer and thus protect against metabolic disorders. Here, we expect that both Akkermansia muciniphila supplementation and flagellin immunization will promote a healthy stable host-microbiota relationship by keeping the intestinal microbiota at a safe distance and may offer protection against emulsifier-induced metabolic alterations.
Aim 3. Examine metabolic disease- and emulsifier consumption-associated mucus-penetrating bacteria in humans. Here, we predict that we will confirm an altered microbiota localization in the mucosa of patients with metabolic abnormalities, associated with enrichment of select bacteria members. We predict that there will be bacterial members that positively correlate with the severity of metabolic alterations, supporting the notion that mucus-infiltrating microbiota plays a direct role in promoting metabolic alterations. The isolation of invaders will also enable to identify human-derived bacteria able to confer metabolic alterations, and we predict that encroached bacteria isolated from patients with metabolic disorders will have the ability to instigate inflammation, obesity and associated metabolic disorders.