Parkinson's disease: does it all start with gut inflammation?

Project Information

PD-GUT

Grant agreement ID: 101003329

DOI

10.3030/101003329

EC signature date 2 April 2021

Start date 1 December 2021

End date 31 May 2028

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 999 722,50

EU contribution

€ 1 999 722,50

Coordinated by

INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE
France

Periodic Reporting for period 3 - PD-GUT (Parkinson's disease: does it all start with gut inflammation?)

Reporting period: 2024-07-01 to 2025-12-31

Summary of the context and overall objectives of the project

The PD-GUT project is concerned with the origin of Parkinson's disease (PD), in particular whether PD begins in the gut. Traditionally, PD is considered a brain-only disease, but recent observations suggest that gastrointestinal (GI) tract involvement precedes motor symptoms. This project explores the hypothesis that gut inflammation is the initial trigger for PD. Understanding the early mechanisms of PD could lead to groundbreaking diagnostic, preventive, and therapeutic strategies. As PD affects millions of people worldwide, identifying its intestinal origins may transform disease management, improve patient outcomes, and reduce the societal and economic burden. The overall goal is to unravel the role of gut inflammation as the first insult in the development of PD, with the ultimate goal of identifying novel mediators involved in immune cell contributions to neurodegeneration. The project uses interdisciplinary approaches combining neuroscience, immunology and microbiology with advanced methodologies such as human induced pluripotent stem cells, three-dimensional model systems, organ-on-a-chip and single cell analysis. In addition to its potential to transform the understanding and treatment of PD, findings from the PD-GUT project could have significant implications for the study of other enteric diseases and microbial biology. Insights into the role of the gut in PD may influence treatment strategies for several conditions associated with gut inflammation and microbiome dysbiosis, highlighting the broader relevance of this groundbreaking research.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Achievements which have been made in the PD-GUT project including the following:

- To understand how LRRK2 shapes the host environment, we used RNA sequencing on infected macrophage subpopulations to simultaneously analyze host and pathogen transcriptomes.
- We have successfully developed human-induced pluripotent stem cell (iPSC)-derived intestinal organoids (HIOs) that integrate isogenic macrophages and enteric neurons. To characterize the HIOs, we employed immunohistochemical techniques. These organoids closely mimic the cellular composition and functionality of the human intestine. Infection models in HIOs have been successfully established. These models provide a valuable tool to analyze the role of inflammation in intestinal proteinophaty.
- We developed midbrain organoids containing isogenic iPSC-derived microglia and characterized them using immunohistochemistry and scRNAseq. To improve reproducibility and promote long-term neuronal maturation and microglial integration, we implemented a bioreactor-based method to generate midbrain organoids. Results indicate increased survival of dopaminergic neurons, improved tissue morphology and integrity for long-term culture. Immunohistochemical analysis showed an increase in cells positive for mature dopaminergic markers and a decrease in apoptotic signals in bioreactor-grown organoids. We performed high-performance liquid chromatography (HPLC) measurements of neurotransmitters and single-cell RNA sequencing to compare functionality and neuroelectric activity.
- We fabricated an intestinal microchip that will allow the analysis of inflammatory responses to proteotoxic stress.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

One of the major milestones of the PD-GUT project was the successful development of human intestinal organoids (HIOs) using an innovative 3D mechanically active gut-on-chip platform (in an international collaboration). This cutting-edge technology represents a significant advance in our ability to accurately model the human intestinal environment. The gut-on-chip platform mimics the physiological conditions of the human gut, including peristaltic motion and fluid flow, providing a dynamic and realistic environment for the growth and function of HIOs. This development enables more precise study of the interactions between intestinal epithelial cells, the microbiome and immune cells, which are critical to understanding the early stages of PD pathogenesis associated with intestinal inflammation.

In addition to advances in gut modeling, the PD-GUT project has also pioneered a novel bioreactor-based method for generating midbrain organoids. This method greatly enhances the maturation of midbrain organoids in a three-dimensional (3D) environment that closely mimics the in vivo conditions of human brain development. The bioreactor system facilitates the efficient exchange of nutrients and waste products, promoting the growth and differentiation of stem cells into mature, functional neuronal tissue. This breakthrough allows us to study the complex interactions between the gut and the brain at a higher level of sophistication, providing critical insights into how gut-derived signals may contribute to neurodegenerative processes in Parkinson's disease.

Dissemination of our results is expected to stimulate further research and collaboration, accelerating the discovery of novel diagnostic and therapeutic strategies for PD and other related neurodegenerative diseases and inflammatory bowel diseases.

Parkinson's disease Intestinal and Brain Organoids