Neutrophil–microglia communication through the C3–C3aR1 axis contributes to secondary neuroinflammation after traumatic brain injury
5 affiliations
- 1Department of Neurosurgery, Tianjin Neurological Institute, State Key Laboratory of Experimental Hematology, Laboratory of Post-Neuroinjury Neurorepair and Regeneration in Central Nervous System Tianjin and Ministry of Education, Tianjin Medical University General Hospital
- 2Department of Physical and Rehabilitation Medicine, Tianjin Medical University General Hospital
- 3Department of Neurology and Institute of Neurology of First Affiliated Hospital, Institute of Neuroscience, and Fujian Key Laboratory of Molecular Neurology, Fujian Medical University
- 4Department of Neurosurgery, Tianjin HuanHu Hospital
- 5Precision Medicine Center, Tianjin Medical University General Hospital
Abstract
Background: Traumatic brain injury (TBI) triggers a rapidly evolving neuroinflammatory response that contributes to secondary brain injury. Although infiltrating leukocytes and resident microglia are both prominent components of this response, the cellular signals that connect peripheral immune-cell recruitment to microglial state remodeling remain incompletely defined.
Methods: We integrated and reanalyzed publicly available single-cell RNA-sequencing datasets from mouse TBI models to define temporal changes in brain-cell composition and transcriptional states. CellChat and NicheNet were used to prioritize candidate neutrophil-to-microglia signaling pathways. The predicted cellular distribution of C3 and C3aR1 was evaluated by immunofluorescence and flow cytometry. The effects of JR14a treatment on microglial inflammatory responses, blood–brain barrier (BBB) integrity, and neurological outcomes were examined in a mouse TBI model. Single-Cell rEgulatory Network Inference and Clustering (SCENIC), CellOracle, a gene regulatory network inference and in silico transcription-factor perturbation framework, and scTenifoldKnk, a single-cell gene regulatory network-based virtual knockout framework, were used for gene regulatory network inference and in silico transcription-factor perturbation analyses in C3ar1 -high microglia.
Results: Analysis of 254,512 cells revealed a transient increase in infiltrating neutrophils during the acute phase of TBI and the emergence of inflammatory microglial states. CellChat and NicheNet independently prioritized C3-associated signaling between neutrophils and Microglia4. C3 expression was enriched in infiltrating neutrophils, whereas C3ar1 was preferentially expressed by inflammatory microglia. Flow cytometry showed that C3aR1-positive microglia expressed higher levels of IL-1β and TNF-α than C3aR1-negative microglia. JR14a treatment reduced microglial inflammatory cytokine production, preserved Claudin-5 expression, limited Evans blue extravasation, and improved neurological and cognitive outcomes after TBI. Exploratory regulatory analyses further prioritized Ets2, Fosl2, and Irf7 as candidate regulators of the C3ar1 -high microglial program.
Conclusions: These findings implicate a neutrophil-associated C3/C3a–C3aR1 communication pathway in inflammatory microglial remodeling after TBI and support further investigation of C3aR1-associated signaling as a therapeutic target for secondary neuroinflammation.
Related
- CHBP-loaded mesoporous polydopamine nanoparticles attenuate neuroinflammation and reprogram microglia-neuron crosstalk for spinal cord injury repair
- Microglia and neuroinflammation: function, heterogeneity, and crosstalk
- Microglia-targeted delivery of MCC950 suppresses NLRP3–IL-18-mediated neuroinflammation and retinal injury in retinal vein occlusion
- Benzene metabolite catechol promotes microglia-mediated neuroinflammation in Alzheimer’s disease via regulating NF-κB signaling
- NEMO (IKKγ) citrullination in microglia promotes neuroinflammation in the post-ischemic brain
BibTeX
@article{ma2026neutrophilmicroglia,
title = {{Neutrophil–microglia communication through the C3–C3aR1 axis contributes to secondary neuroinflammation after traumatic brain injury}},
author = {Tianrui Ma and Yichi Zhang and Xiran Wang and Xiangru Ren and Linan Jiao and Kaifeng Pang and Chenyang Liu and Zijian Zhou and Pengbo Zhao and Hao Zhang and Ying Fu and Lei Li and Yang Li and Zilong Zhao},
journal = {Frontiers in Immunology},
year = {2026},
month = oct,
doi = {10.3389/fimmu.2026.1979527},
url = {https://www.frontiersin.org/articles/10.3389/fimmu.2026.1979527/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Neutrophil–microglia communication through the C3–C3aR1 axis contributes to secondary neuroinflammation after traumatic brain injury
AU - Tianrui Ma
AU - Yichi Zhang
AU - Xiran Wang
AU - Xiangru Ren
AU - Linan Jiao
AU - Kaifeng Pang
AU - Chenyang Liu
AU - Zijian Zhou
AU - Pengbo Zhao
AU - Hao Zhang
AU - Ying Fu
AU - Lei Li
AU - Yang Li
AU - Zilong Zhao
PY - 2026
DA - 2026/10/23
JO - Frontiers in Immunology
DO - 10.3389/fimmu.2026.1979527
UR - https://www.frontiersin.org/articles/10.3389/fimmu.2026.1979527/full
AB - Background: Traumatic brain injury (TBI) triggers a rapidly evolving neuroinflammatory response that contributes to secondary brain injury. Although infiltrating leukocytes and resident microglia are both prominent components of this response, the cellular signals that connect peripheral immune-cell recruitment to microglial state remodeling remain incompletely defined. Methods: We integrated and reanalyzed publicly available single-cell RNA-sequencing datasets from mouse TBI models to define temporal changes in brain-cell composition and transcriptional states. CellChat and NicheNet were used to prioritize candidate neutrophil-to-microglia signaling pathways. The predicted cellular distribution of C3 and C3aR1 was evaluated by immunofluorescence and flow cytometry. The effects of JR14a treatment on microglial inflammatory responses, blood–brain barrier (BBB) integrity, and neurological outcomes were examined in a mouse TBI model. Single-Cell rEgulatory Network Inference and Clustering (SCENIC), CellOracle, a gene regulatory network inference and in silico transcription-factor perturbation framework, and scTenifoldKnk, a single-cell gene regulatory network-based virtual knockout framework, were used for gene regulatory network inference and in silico transcription-factor perturbation analyses in C3ar1 -high microglia. Results: Analysis of 254,512 cells revealed a transient increase in infiltrating neutrophils during the acute phase of TBI and the emergence of inflammatory microglial states. CellChat and NicheNet independently prioritized C3-associated signaling between neutrophils and Microglia4. C3 expression was enriched in infiltrating neutrophils, whereas C3ar1 was preferentially expressed by inflammatory microglia. Flow cytometry showed that C3aR1-positive microglia expressed higher levels of IL-1β and TNF-α than C3aR1-negative microglia. JR14a treatment reduced microglial inflammatory cytokine production, preserved Claudin-5 expression, limited Evans blue extravasation, and improved neurological and cognitive outcomes after TBI. Exploratory regulatory analyses further prioritized Ets2, Fosl2, and Irf7 as candidate regulators of the C3ar1 -high microglial program. Conclusions: These findings implicate a neutrophil-associated C3/C3a–C3aR1 communication pathway in inflammatory microglial remodeling after TBI and support further investigation of C3aR1-associated signaling as a therapeutic target for secondary neuroinflammation.
SN - 1664-3224
ER -