Extracellular vesicles from microglial cells activated by abnormal heparan sulfate oligosaccharides from Sanfilippo
Chloé Dias1, Nissrine Ballout1, Guillaume Morla1
1Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), Inserm U1291, CNRS U5051, University of Toulouse, Toulouse, France.
Background:
In mucopolysaccharidosis type III (MPS III, also known as Sanfilippo syndrome), a pediatric neurodegenerative disorder, accumulation of abnormal glycosaminoglycans (GAGs) induces severe neuroinflammation by triggering the microglial pro-inflammatory cytokines production via a TLR4-dependent pathway. But the extent of the microglia contribution to the MPS III neuropathology remains unclear. Extracellular vesicles (EVs) mediate intercellular communication and are known to participate in the pathogenesis of adult neurodegenerative diseases. However, characterization of the molecular profiles of EVs released by MPS III microglia and their effects on neuronal functions have not been described.
Methods:
Here, we isolated EVs secreted by the microglial cells after treatment with GAGs purified from urines of Sanfilippo patients (sfGAGs-EVs) or from age-matched healthy subjects (nGAGs-EVs) to explore the EVs' proteins and small RNA profiles using LC-MS/MS and RNA sequencing. We next performed a functional assay by immunofluorescence following nGAGs- or sfGAGs-EVs uptake by WT primary cortical neurons and analyzed their extensions metrics after staining of βIII-tubulin and MAP2 by confocal microscopy.
Results:
Functional enrichment analysis for both proteomics and RNA sequencing data from sfGAGs-EVs revealed a specific content involved in neuroinflammation and neurodevelopment pathways. Treatment of cortical neurons with sfGAGs-EVs induced a disease-associated phenotype demonstrated by a lower total neurite surface area, an impaired somatodendritic compartment, and a higher number of immature dendritic spines.
Conclusions:
This study shows, for the first time, that GAGs from patients with Sanfilippo syndrome can induce microglial secretion of EVs that deliver a specific molecular message to recipient naive neurons, while promoting the neuroinflammation, and depriving neurons of neurodevelopmental factors. This work provides a framework for further studies of biomarkers to evaluate efficiency of emerging therapies.
Insights
Sanfilippo syndrome (MPS III) microglia release extracellular vesicles (EVs) carrying disease-associated molecules. These EVs impair neuronal development and promote neuroinflammation, offering new therapeutic targets.
Area of Science:
- Neuroscience
- Cell Biology
- Genetics
Background:
- Mucopolysaccharidosis type III (MPS III), or Sanfilippo syndrome, is a pediatric neurodegenerative disorder.
- Abnormal glycosaminoglycans (GAGs) in MPS III trigger microglial pro-inflammatory cytokine production, but microglia's role in neuropathology is unclear.
- Extracellular vesicles (EVs) mediate intercellular communication and are implicated in adult neurodegenerative diseases.
Purpose of the Study:
- To characterize the molecular profiles of EVs released by MPS III microglia.
- To investigate the effects of these EVs on neuronal functions.
- To understand the contribution of microglial EVs to MPS III neuropathology.
Main Methods:
- Isolated EVs from microglial cells treated with patient-derived GAGs (sfGAGs-EVs) or healthy controls (nGAGs-EVs).
- Analyzed EV protein and small RNA content using LC-MS/MS and RNA sequencing.
- Assessed functional effects of EVs on primary cortical neurons via immunofluorescence and confocal microscopy.
Main Results:
- Proteomic and RNA sequencing of sfGAGs-EVs revealed pathways linked to neuroinflammation and neurodevelopment.
- sfGAGs-EVs induced a disease-associated phenotype in neurons, including reduced neurite surface area and impaired dendritic spines.
- Neurons treated with sfGAGs-EVs showed deficits in somatodendritic compartments and immature dendritic spines.
Conclusions:
- Microglial EVs from Sanfilippo syndrome patients carry specific molecular cargo that impacts neuronal health.
- These EVs promote neuroinflammation and hinder neurodevelopmental processes in recipient neurons.
- This study provides a foundation for developing EV-based biomarkers for MPS III therapies.
