Periodic Reporting for period 1 - MULTIMOYA (Multi-omics characterization of immune triggers in Moyamoya disease)
Berichtszeitraum: 2023-08-01 bis 2026-01-31
The MULTIMOYA project focuses on a rare disorder called Moyamoya, with the overall ambitious aim to solve the etiology of this mysterious disease. Moyamoya is characterized by progressive narrowing of arteries at the base of the brain leading to stroke. While genetic mutations in ring finger protein 213 (RNF213) are a risk factor for Moyamoya, further underlying mechanisms remain elusive. Recently, we and others discovered RNF213 as a novel antimicrobial protein, strongly suggesting a role for the immune response to infection in the development of Moyamoya. Building on these findings, MULTIMOYA will carry out advanced multi-omics analyses on Moyamoya patient-derived cells to investigate the link between RNF213, infection, immunity and arterial occlusion. In this way, MULTIMOYA will provide unprecedented insight into fundamental processes that link cellular immunity with vascular disease that might lead to novel treatment strategies for Moyamoya patients and millions of people carrying founder mutations in RNF213.
A first main achievement comprises the genetic diagnosis of Moyamoya patients included in the project. Blood samples were collected for twelve patients and whole exosome sequencing resulted in a genetic diagnosis for eight patients. Variants in the major susceptibility gene RNF213 were found in three patients, while five patients had other underlying genetic conditions, including pathogenic variants in ACTA2, SAMHD1 and NFIA. Second, we conducted an in-depth single cell spatial proteomics analysis on an occluded artery retrieved post-mortem from one idiopathic patient. Using two different spatial techniques, this analysis revealed contractile-to-synthetic phenotypic switching of vascular smooth muscle cells associated with proliferation of these cells in the intima. Most interestingly, increased expression of cellular fibronectin in the occluded lesion was associated with increased levels in patients’ plasma, providing a rational for cellular fibronectin as potential tissue leakage biomarker for Moyamoya disease. Along with the genetic data, the results of these spatial and plasma proteomics analyses have been described in a first manuscript that is currently under review for publication. Finally, we generated induced pluripotent stem cells (iPSCs) from skin fibroblasts of two Moyamoya patients. These cells are now available to differentiate into various vascular and immune cell types relevant for the disease. These cells constitute an important research tool for this and future projects.
The present project aims to investigate the exciting hypothesis that a rare cerebrovascular disease might originate from an aberrant immune response to infection in genetically predisposed individuals. The disease in scope is called Moyamoya, a Japanese name pointing to the fact that incidence is highest in East Asia. The latter results from the fact that predisposing mutations in RNF213 are widespread in the Asian population. Our discovery of RNF213 as a key antimicrobial protein and its function as a binding platform for proteins modified by ISG15 sheds new light on the potential involvement of infection diseases and associated immune responses in the development of Moyamoya. While the main goal is to investigate the above hypothesis from a fundamental point of view, our results could still impact the life of millions of people carrying the p.R4810K RNF213 susceptibility variant in East Asia (including ~2% of the Japanese population). If certain (childhood) infections indeed trigger Moyamoya disease onset in these patients, prophylactic vaccination, therapy or reduced exposure to the culprit pathogen(s) could be considered. In addition, a better understanding of the molecular events driving the pathogenic proliferation of vascular smooth muscle cells in occlusive lesions could lead to novel diagnostic tests or therapies for Moyamoya disease. The potential plasma biomarker already identified in the project exemplifies this, but needs further validation in larger patient cohorts. To gain molecular insight into Moyamoya disease mechanisms, an animal model would be a tremendous breakthrough, along with knowledge on dysregulated pathways mapped by (spatial) omics characterization of patient samples, two focus areas of MULTIMOYA. In this way, the project will gain fundamental insight into processes that link cellular immunity with vascular remodeling, knowledge that is also highly relevant beyond Moyamoya disease.