CCL2 knockdown attenuates post-traumatic external cerebral herniation by suppressing JAK-STAT signaling following traumatic brain injury.

BACKGROUND

C-C motif chemokine ligand 2 (CCL2) contributes to post-traumatic neuroinflammation and blood-brain barrier (BBB) disruption, but its role in post-traumatic external cerebral herniation and endothelial JAK-STAT signaling remains unclear.

METHODS

CCL2-knockdown BEND3 cells were subjected to 4 h oxygen-glucose deprivation and 24 h reoxygenation. Recombinant CCL2 rescue and the JAK-STAT inhibitor SC99 were used to assess pathway directionality. Cell injury, apoptosis, JAK2/STAT1/STAT3 phosphorylation, transendothelial electrical resistance, permeability and tight junction proteins were evaluated. In mice, sh-CCL2 was delivered before traumatic brain injury (TBI). Neurological function, inflammatory mediators, BBB integrity, intracranial pressure, cerebral perfusion, venous morphology, external cerebral herniation and histological injury were assessed.

RESULTS

CCL2 knockdown reduced LDH release and apoptosis, suppressed JAK2, STAT1 and STAT3 phosphorylation, increased transendothelial electrical resistance, reduced permeability and restored ZO-1, Occludin and Claudin-5. Recombinant CCL2 partially reversed these effects, supporting an upstream contribution of CCL2 to JAK-STAT activation. In vivo, sh-CCL2 improved mNSS but not Garcia score or brain water content (85.29 ± 3.50% in TBI vs. 84.73 ± 3.23% in TBI + sh-CCL2; P = 0.829). It also reduced inflammatory mediators and Evans blue extravasation, decreased mean intracranial pressure from 20.60 ± 0.76 to 12.19 ± 0.44 mmHg, increased cerebral blood flow from 62.10 ± 3.13 to 83.43 ± 4.65 mL/100 g/min and reduced external cerebral herniation volume from 18.70 ± 0.55 to 7.94 ± 0.38 mm3.

CONCLUSION

CCL2 promotes OGD/R-induced endothelial injury partly through JAK-STAT activation. CCL2 knockdown may alleviate TBI-related neurovascular dysfunction and post-traumatic external cerebral herniation by preserving endothelial barrier integrity and improving cerebral venous and perfusion abnormalities.