Summary: Researchers have developed a new method to pinpoint a subset of astrocytes that appear to play a role in the development and progression of multiple sclerosis.
Source: Brigham and Women’s Hospital
Rare cell types can have an undue influence on human health. Previous research has suggested that a subset of astrocytes—star-shaped cells in the brain and spinal cord—may be responsible for multiple sclerosis (MS), a disease in which the immune system attacks the covering that protects nerves.
But finding these rare cells is no easy task—to pinpoint them, investigators need to identify unique surface markers that can distinguish these culprit cells from others. Single-cell RNA sequencing can help find them, even in the absence of distinguishing surface marker, but this technique can become extremely expensive.
To address this problem, a team led by investigators from Brigham and Women’s Hospital, a founding member of the Mass General Brigham health care system, developed FIND-seq, which combines nucleic acid cytometry, microfluidics, and droplet sorting to isolate and analyze rare cells of interest based on the expression of mRNA biomarkers detected by digital droplet PCR.
Using this method, the team analyzed in great detail a population of astrocytes that drives central nervous system inflammation and neurodegeneration. When used in combination with other tools, FIND-seq identified signaling pathways controlled by the mineralocorticoid receptor NR3C2 and the nuclear receptor corepressor 2 that play important roles in the development of pathogenic astrocytes in mice and humans.
In another study, researchers used FIND-seq to identify mechanisms used by HIV to “hide” in immune cells in patients treated with anti-retroviral therapies.
“These findings identify novel targets for therapeutic intervention in neurologic diseases such as MS,” said corresponding author Francisco Quintana, Ph.D., of the BWH Department of Neurology. The team is working to develop novel small molecules which could be used to target this pathway therapeutically.
About this multiple sclerosis research news
Author: Press Office
Source: Brigham and Women’s Hospital
Contact: Press Office – Brigham and Women’s Hospital
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Original Research: Closed access.
“Identification of astrocyte regulators by nucleic acid cytometry” by Francisco Quintana et al. Nature
Identification of astrocyte regulators by nucleic acid cytometry
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Astrocytes are heterogeneous CNS-resident glial cells that participate in the pathogenesis of MS and its model experimental autoimmune encephalomyelitis (EAE).
However, few unique surface markers are available for the isolation of astrocyte subsets, preventing their analysis and the identification of candidate therapeutic targets; these limitations are further amplified by the rarity of pathogenic astrocytes.
To address these challenges, we developed FIND-seq (Focused Interrogation of cells by Nucleic acid Detection and Sequencing), a high-throughput microfluidic cytometry method that combines encapsulation of cells in droplets, PCR-based detection of target nucleic acids, and droplet sorting to enable in-depth transcriptomic analyses of cells of interest at single-cell resolution.
We applied FIND-seq to study the regulation of astrocytes characterized by the splicing-driven activation of the transcription factor XBP1, which promotes disease pathology in MS and EAE.
Using FIND-seq in combination with conditional knock-out mice, in vivo CRISPR/Cas9-driven genetic perturbation studies, and bulk and single-cell RNA-seq analyses of mouse EAE and human MS samples, we identified a new role for the nuclear receptor NR3C2 and its corepressor NCOR2 in limiting XBP1-driven pathogenic astrocyte responses. In summary, FIND-seq enabled the identification of a therapeutically targetable mechanism that limits XBP1-driven pathogenic astrocyte responses.
FIND-seq allows the investigation of previously inaccessible cells, including rare cell subsets defined by unique gene expression signatures or other nucleic acid markers.