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Updated: Mar 19, 2026
Isolation and Flow Cytometric Assessment of Neuroimmune Interactions in a Mini-Stroke Murine Model
Published on: June 20, 2025
mTORC1 pathway disruption ameliorates brain inflammation following stroke via a shift in microglia phenotype from M1
Daojing Li1, Chunjiong Wang2, Yang Yao1
1Department of Neurology and Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, China.
Abstract:
Inflammatory factors secreted by microglia play an important role in focal ischemic stroke. The mammalian target of rapamycin (mTOR) pathway is a known regulator of immune responses, but the role that mTORC1 signaling plays in poststroke neuroinflammation is not clear. To explore the relationship between microglial action in the mTORC1 pathway and the impact on stroke, we administered the mTORC1 inhibitors sirolimus and everolimus to mice. Presumably, disrupting the mTORC1 pathway after focal ischemic stroke should clarify the subsequent activity of microglia. For that purpose, we generated mice deficient in the regulatory associated protein of mTOR (Raptor) in microglia, whose mTORC1 signaling was blocked, by crossing Raptor loxed (Raptorflox/flox) mice with CX3CR1CreER mice, which express Cre recombinase under the control of the CX3C chemokine receptor 1 promoter. mTORC1 blockade reduced lesion size, improved motor function, dramatically decreased production of proinflammatory cytokines and chemokines, and reduced the number of M1 type microglia. Thus, mTORC1 blockade apparently attenuated behavioral deficits and poststroke inflammation after middle cerebral artery occlusion by preventing microglia polarization toward the M1 type.-Li, D., Wang, C., Yao, Y., Chen, L., Liu, G., Zhang, R., Liu, Q., Shi, F.-D., Hao, J. mTORC1 pathway disruption ameliorates brain inflammation following stroke via a shift in microglia phenotype from M1 type to M2 type.
Insights
Disrupting the mTORC1 pathway in microglia reduces brain inflammation and improves motor function after ischemic stroke by shifting microglia from M1 to M2 types.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Microglia-secreted inflammatory factors are crucial in focal ischemic stroke.
- The mammalian target of rapamycin (mTOR) pathway regulates immune responses, but its role in poststroke neuroinflammation is unclear.
Purpose of the Study:
- To investigate the role of mTORC1 signaling in microglial activation and its impact on stroke outcomes.
- To determine if blocking mTORC1 signaling can mitigate neuroinflammation and improve functional recovery after ischemic stroke.
Main Methods:
- Administered mTORC1 inhibitors (sirolimus, everolimus) to mice post-stroke.
- Generated microglia-specific mTORC1-deficient mice (Raptor knockout in microglia) by crossing Raptor loxed and CX3CR1CreER mice.
- Evaluated lesion size, motor function, cytokine/chemokine production, and microglial phenotype (M1/M2).
Main Results:
- mTORC1 blockade significantly reduced lesion size and improved motor function.
- Proinflammatory cytokine and chemokine production was dramatically decreased.
- The number of M1-type microglia was reduced, indicating a shift away from the pro-inflammatory phenotype.
Conclusions:
- mTORC1 pathway disruption attenuates behavioral deficits and neuroinflammation after ischemic stroke.
- Blocking mTORC1 signaling prevents microglia polarization towards the M1 type, promoting a shift to the M2 phenotype.
- Targeting the mTORC1 pathway in microglia represents a potential therapeutic strategy for stroke recovery.
