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Updated: Sep 14, 2025
Isolation and Flow Cytometric Assessment of Neuroimmune Interactions in a Mini-Stroke Murine Model
Published on: June 20, 2025
Lars2 Deficiency-Induced Mitochondrial Dysfunction Drives the Emergence of a Pro-Inflammatory Stroke-Specific
Qing Zou1, Jianxin Zhou1, Ying Li1
1School of Life Sciences, Shanghai University, Shanghai, China.
Abstract:
Stroke significantly alters microglial immune status beyond the traditional M1/M2 classification. We analyzed single-cell RNA sequencing data from the striatum of hemorrhagic, ischemic, and control mice, revealing activation of mitochondrial autophagy and assembly processes after stroke. Gene Ontology functional enrichment analysis indicated that stroke-associated genes predominantly regulate mitochondrial maintenance, with leucyl-tRNA synthetase 2 (Lars2) markedly upregulated in post-stroke microglia. A distinct microglial subset (Mc) was identified with notably low Lars2 expression. In vitro, Lars2 overexpression enhanced mitochondrial function, reduced pro-inflammatory cytokine release, and suppressed Mc marker gene expression. Cell-cell communication analysis revealed Mc as the most interactive microglial subset following stroke, particularly engaging with neurons. Among neuron-Mc signaling pairs, the neurotrophic factor pleiotrophin-syndecan-4 (PTN-SDC4) ligand-receptor pair emerged as a key mediator. Conditioned media from stressed microglia upregulated neuronal Ptn expression, likely recruiting microglia, as exogenous PTN promoted microglial migration. These findings identify Mc as a stroke-induced microglial population with low Lars2 expression and pro-inflammatory features. The lack of compensatory mitochondrial repair in Mc contributes to pro-inflammatory polarization, positioning Lars2 as a mitochondrial checkpoint linking stroke-induced microglial reprogramming to neuroinflammation.
Insights
Stroke triggers a distinct microglial subset (Mc) with low leucyl-tRNA synthetase 2 (Lars2) expression and pro-inflammatory features. Lars2 deficiency impairs mitochondrial repair, driving neuroinflammation post-stroke.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglial immune status is altered post-stroke, extending beyond M1/M2 classifications.
- Stroke induces changes in mitochondrial autophagy and assembly processes in microglia.
Purpose of the Study:
- To identify novel microglial subsets and molecular mechanisms involved in post-stroke neuroinflammation.
- To investigate the role of leucyl-tRNA synthetase 2 (Lars2) in microglial function and response to stroke.
Main Methods:
- Single-cell RNA sequencing of mouse striatal microglia after hemorrhagic and ischemic stroke.
- Gene Ontology functional enrichment analysis and cell-cell communication analysis.
- In vitro experiments involving Lars2 overexpression and conditioned media treatments.
Main Results:
- A distinct microglial subset (Mc) with low Lars2 expression was identified post-stroke.
- Lars2 deficiency correlated with impaired mitochondrial function and increased pro-inflammatory cytokine release.
- The pleiotrophin-syndecan-4 (PTN-SDC4) pathway was identified as a key mediator in neuron-Mc communication.
Conclusions:
- Mc represents a stroke-induced pro-inflammatory microglial population characterized by low Lars2 expression.
- Lars2 acts as a mitochondrial checkpoint, linking microglial reprogramming to neuroinflammation after stroke.
- Targeting Lars2 or the PTN-SDC4 pathway may offer therapeutic strategies for stroke recovery.
