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Updated: Sep 14, 2025
Identifying Microglia and Peripheral Infiltrating Macrophages in the Injured Spinal Cords Using Flow Cytometry
Published on: June 24, 2025
Targeting RelA/NLRP3/CCL3 axis mitigates microglia inflammatory response and promotes recovery after spinal cord
Wei Song1, Runhan Fu1, Zhongze Yuan2
1Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, Shandong, China; Orthopedic Research Center of Shandong University &Advanced Medical Research Institute, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China.
Abstract:
Spinal cord injury (SCI) leads to loss of motor and sensory function below the lesion site, presenting a lifelong burden of disability. During the acute phase of SCI, microglia develop an inflammatory phenotype, characterized by the NLR family pyrin domain containing 3 (NLRP3) inflammasome signaling activation, exacerbating tissue damage and impeding trauma recovery. However, the molecular mechanisms underlying this process remain unclear. Here we show that conditional knockout of Nlrp3 in microglia using Nlrp3fl/fl; Cx3cr1-CreERT; Rosa26-tdTomato mice (Nlrp3ΔMG) confers neuroprotection by preserving neuron survival and mitigating tissue damage during the acute phase of SCI. Mechanistically, Nlrp3 ablation in microglia attenuates the activation of pyroptosis-related signaling pathways in microglia and suppresses the production of inflammatory cytokines (IL-1β, IL-18, CCL3, and CCL5). Furthermore, we identify RelA as a transcriptional regulator of Nlrp3, binding to its promoter and upregulating its expression in activated microglia. Inhibition of RelA using pyrrolidine dithiocarbamate ammonium (PDTC), a blood-brain barrier permeable drug, effectively downregulates NLRP3 expression and suppresses spinal cord inflammation, thereby contributing to neuroprotection. Our findings demonstrate the crucial role of RelA/NLRP3/CCL3 axis in modulating microglial inflammation and highlight its potential as a therapeutic target to promote recovery post SCI.
Insights
Targeting the RelA/NLRP3/CCL3 axis in microglia offers neuroprotection after spinal cord injury (SCI). Inhibiting NLRP3 inflammasome activation reduces inflammation and promotes recovery from SCI.
Area of Science:
- Neuroscience
- Immunology
- Molecular Biology
Background:
- Spinal cord injury (SCI) causes significant motor and sensory deficits.
- Microglia activation and NLRP3 inflammasome signaling exacerbate SCI-induced damage.
- Molecular mechanisms linking microglial activation to SCI pathology are not fully understood.
Purpose of the Study:
- To investigate the role of NLRP3 inflammasome in microglial activation following SCI.
- To identify molecular regulators of NLRP3 in microglia during SCI.
- To explore therapeutic strategies targeting microglial inflammation for SCI recovery.
Main Methods:
- Conditional knockout of Nlrp3 in microglia (Nlrp3ΔMG mice).
- Assessment of neuroprotection, tissue damage, and inflammatory markers post-SCI.
- Analysis of pyroptosis pathways and cytokine production in microglia.
- Identification and validation of RelA as an NLRP3 transcriptional regulator.
- Pharmacological inhibition of RelA using PDTC.
Main Results:
- Nlrp3 deletion in microglia conferred neuroprotection and reduced tissue damage in SCI.
- NLRP3 ablation attenuated pyroptosis and suppressed inflammatory cytokine release (IL-1β, IL-18, CCL3, CCL5).
- RelA was identified as a transcriptional activator of Nlrp3 in activated microglia.
- PDTC treatment inhibited RelA/NLRP3 signaling, reduced spinal cord inflammation, and promoted neuroprotection.
Conclusions:
- The RelA/NLRP3/CCL3 axis is critical for microglial inflammatory responses in SCI.
- Targeting microglial NLRP3 inflammasome activation presents a promising therapeutic avenue for SCI.
- Inhibition of RelA offers a potential strategy to mitigate SCI-induced neuroinflammation and enhance recovery.
