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Updated: Feb 24, 2026
Isolation and Flow Cytometric Assessment of Neuroimmune Interactions in a Mini-Stroke Murine Model
Published on: June 20, 2025
Social interaction modulates the neuroinflammatory response to global cerebral ischemia in male mice
Monica M Gaudier-Diaz1, Ning Zhang1, Adam H Haines2
1Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA; Neuroscience Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.
Abstract:
Social isolation is a risk factor for cardiovascular and cerebrovascular diseases, although the underlying mechanisms remain underspecified. Considering the potential of microglia to become sensitized by stressors and their role in neuroinflammation, we hypothesized that social isolation primes microglia, resulting in an exaggerated neuroimmune response to experimental cerebral ischemia. First, major histocompatibility complex II (MHC II) gene expression, an indicator of microglial priming, was compared between mice that were socially isolated or pair-housed. MHC II increased in the hippocampus and cortex of socially isolated mice, which is suggestive of isolation-induced microglial priming. In experiment 2, isolated and pair-housed mice underwent ∼8min of global cerebral ischemia. Hippocampal mRNA expression of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) was significantly increased among both isolated and pair-housed ischemia groups relative to sham controls. Hippocampal expression of interleukin 1 beta (IL-1β) and cortical TNF-α, IL-1β and IL-6, were significantly increased 24-h post ischemia in isolated mice, but not pair-housed mice, relative to controls. Ischemia-induced increases in microglial cell body area and percent area fraction of ionized calcium binding adaptor molecule 1 (Iba-1) positive staining were also observed in isolated, but not pair-housed mice, relative to controls. For experiment 3, brain sections from socially isolated and pair-housed mice underwent 15min of oxygen glucose deprivation (OGD), an ex vivo model of cerebral ischemia. IL-6 gene expression was significantly elevated following OGD only in hippocampi from mice that had been socially isolated, indicating that isolation prior to ischemia is sufficient to modulate the neuroinflammatory response. Together, these data suggest microglial priming as a possible mechanism underlying the detrimental effects of social isolation on cerebral ischemia outcome.
Insights
Social isolation primes microglia, leading to heightened neuroinflammation and worse outcomes following cerebral ischemia. This priming effect exacerbates the brain's immune response to stroke-like events.
Area of Science:
- Neuroscience
- Immunology
- Cardiovascular Research
Background:
- Social isolation is a known risk factor for cardiovascular and cerebrovascular diseases.
- The precise mechanisms linking social isolation to these conditions are not fully understood.
- Microglia, the brain's immune cells, can be sensitized by stress and play a role in neuroinflammation.
Purpose of the Study:
- To investigate if social isolation primes microglia, causing an exaggerated neuroimmune response to cerebral ischemia.
- To explore the molecular and cellular changes in microglia following social isolation and subsequent ischemic events.
Main Methods:
- Compared major histocompatibility complex II (MHC II) gene expression in socially isolated versus pair-housed mice.
- Induced global cerebral ischemia in mice and assessed inflammatory markers (TNF-α, IL-6, IL-1β) and microglial activation (Iba-1).
- Utilized an ex vivo oxygen-glucose deprivation (OGD) model to examine the direct impact of isolation on ischemic brain tissue.
Main Results:
- Socially isolated mice showed increased MHC II expression, indicating microglial priming.
- Following ischemia, isolated mice exhibited elevated levels of inflammatory cytokines (IL-1β, TNF-α, IL-6) and increased microglial activation (Iba-1) compared to pair-housed mice.
- Ex vivo OGD experiments confirmed that prior social isolation was sufficient to enhance the inflammatory gene expression (IL-6) in response to ischemia.
Conclusions:
- Social isolation primes microglia, making them more reactive to cerebral ischemia.
- This microglial priming is a potential mechanism contributing to the negative effects of social isolation on cerebrovascular health.
- Findings highlight the critical role of social environment in modulating brain's response to injury.
