TMU Study Reveals CCL5/CCR5 Signaling as a Vital Neuroprotective Axis After Mild Traumatic Brain Injury

Summary

A study led by researchers at Taipei Medical University (TMU) has identified the signaling molecule CCL5 (RANTES) as a critical factor in restoring immune homeostasis and mitigating oxidative stress following mild traumatic brain injury (mTBI). The findings reveal that CCL5 signaling is essential for activating the brain’s antioxidant defenses; its absence, rather than its presence, leads to prolonged neuroinflammation and impaired recovery. Using experimental models, the researchers demonstrated that supplementing this pathway through intranasal administration of recombinant CCL5 can effectively reduce neuronal damage and promote tissue repair.

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When CCL5 Deficiency Triggers Lasting Damage

Mild traumatic brain injury is often clinically manageable, yet many patients suffer from persistent cognitive and mood disturbances. While conventional views often label chemokines as purely detrimental, this study highlights a protective role for CCL5.

Following mTBI, the brain requires specific molecular signals to balance the immune response and clear reactive oxygen species (ROS). The TMU team found that without sufficient CCL5 signaling, the brain fails to activate key antioxidant enzymes, leading to a “lethal” cycle of oxidative stress and chronic neurodegeneration. Therefore, understanding how CCL5 orchestrates this repair process is critical for improving long-term recovery outcomes.

Key Findings: CCL5 Coordinates Neurorepair and Immune Balance

The study detailed several mechanisms through which CCL5/CCR5 signaling facilitates recovery after mild brain injury:

• Activation of Antioxidant Defenses: CCL5 is required to trigger essential enzymes, specifically GPX1 and SOD1, which neutralize harmful ROS in the injured cortex
  
  

  Figure. CCL5 deficiency is associated with greater oxidative stress and neuronal damage after mild traumatic brain injury. After mild traumatic brain injury (mTBI), mice lacking CCL5 showed more severe neuronal damage and higher oxidative stress in the cortex compared with normal mice. The data also show reduced antioxidant defense markers in CCL5-deficient mice, supporting the protective role of CCL5 signaling in brain recovery after injury.

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• Promotion of M2 Microglial Polarization: Through a CCR5-dependent mechanism involving NFATc2 signaling, CCL5 directs microglia toward a reparative “M2-like” phenotype. This state suppresses pro-inflammatory cytokines while enhancing the phagocytic clearance of cellular debris.
• Restoration of the Neural Environment: By fostering a protective microenvironment, CCL5 supports axonal regeneration and remyelination, which are vital for restoring sensory and motor functions.

“Our findings suggest that CCL5 is not a driver of damage, but rather a central orchestrator of the brain’s self-repair mechanism after mild injury,” said Szu-Yi Chou, professor in the Ph.D. Program for Neural Regenerative Medicine at Taipei Medical University and a member of the TMU Research Center of Neuroscience.

Study Design: Linking Molecular Signals to Post-Injury Inflammation

The TMU research team conducted molecular and cellular analyses to examine inflammatory responses following mild traumatic brain injury. The study investigated changes in chemokine signaling, with a particular focus on CCL5 expression and its downstream effects on immune regulation.

By integrating experimental data with pathway analysis, the researchers were able to characterize how CCL5 contributes to inflammation modulation and identify its potential as a therapeutic target.

Implications for Treating Post-Traumatic Brain Injury

Current mTBI therapies primarily address symptoms rather than the underlying molecular failure. By identifying the CCL5-CCR5 axis as a key driver of immune resolution, this study provides a new therapeutic strategy.

Targeting this pathway—not by inhibiting it, but by exogenously supplementing CCL5—offers a promising approach to mitigate chronic neuroinflammation and improve functional outcomes for patients experiencing the lasting effects of mTBI. This research underscores the necessity of temporal and spatial specificity in neuroimmune interventions.

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• Reference
  Original research article: CCL5/RANTES signaling in inflammation dysregulation after mild traumatic brain injuryJournal of Biomedical Science (2026).