Brain cell-released Cyclophilin A induces neuroinflammation and exacerbates blood–brain barrier injury in acute ischemic stroke

 What research are you initiating to prevent this from happening? DOING NOTHING, LIKE USUAL?

With NO leadership anywhere in stroke NOTHING IS EVER ACCOMPLISHED!

Our fucking failures of a stroke associations are completely useless in getting stroke solved to 100% recovery. I'll be a bad person and hope every single employee in them get blasted hard by their stroke when they are the 1 in 4 per WHO that has a stroke! 

Brain cell-released Cyclophilin A induces neuroinflammation and exacerbates blood–brain barrier injury in acute ischemic stroke

• 

  Enyue Chen 1

• 

  Qihui Wu 2

• Y

  Yunwen Xue 2

• 

  Shixiong Huang 1*

• 

  Yong Gu 2*

• 1. Department of Neurology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou, China

• 2. Clinical Research Center, Affiliated Chinese Medicine, Hainan Medical University, Haikou, China

Abstract

Background: 

Excessive neuroinflammation mediates blood–brain barrier (BBB) disruption and poor outcomes after acute ischemic stroke (AIS). Cyclophilin A (CypA), when released into the extracellular space (designated as eCypA), may participate in inflammatory reactions and vascular dysfunction. However, its role in regulating neuroinflammation and BBB injury in AIS, as well as the therapeutic potential of targeting eCypA remain unclear.

Methods: 

ELISA was used to detect eCypA release in serum from 22 AIS patients (17 mild, 5 severe; 13 males, 9 females; mild: age 65.41 ± 10.20 years, NIHSS 2.88 ± 1.45; severe: age 64.00 ± 5.04 years, NIHSS 9.40 ± 3.29; blood sampled within 48 h of onset), in serum/cerebrospinal fluid (CSF) from transient middle cerebral artery occlusion (tMCAO) rats, and in supernatants from BV2 (microglia) or bEnd.3 (brain microvascular endothelial cells) exposed to oxygen–glucose deprivation/reoxygenation (OGD/R) or lipopolysaccharide (LPS). Nine-week-old male Sprague–Dawley rats (n = 5 per group) underwent 1.5 h of tMCAO via the intraluminal suture method followed by 24 h of reperfusion before sampling. These rats received intracerebroventricular injection of cyclophilin A-binding heptameric peptide (C46) before tMCAO establishment. Cerebral infarct volume was measured via TTC staining. BBB permeability was assessed by Evans blue extravasation. Western blot was employed to determine protein levels of tight junction (TJ) proteins, matrix metalloproteinases (MMPs) and proinflammatory mediators. Microglial activation was evaluated by immunofluorescence.

Results: 

eCypA levels were significantly elevated in AIS patient serum (1.74 ± 0.23 ng/mL in mild, 2.39 ± 0.09 ng/mL in severe vs. 1.30 ± 0.19 ng/mL in healthy controls, p < 0.001), in tMCAO rat serum (2.57 ± 0.14 vs. 1.62 ± 0.07 ng/mL, p < 0.001) and CSF (2.14 ± 0.23 vs. 1.47 ± 0.19 ng/mL, p < 0.001), as well as in the supernatants of OGD/R-challenged BV2 (0.92 ± 0.01 vs. 0.55 ± 0.03 ng/mL, p < 0.001) and bEnd.3 cells (1.10 ± 0.05 vs. 0.52 ± 0.03 ng/mL, p < 0.001) and LPS-induced BV2 cells (1.12 ± 0.08 vs. 0.56 ± 0.13 ng/mL, p < 0.001) compared with their respective control groups. The eCypA inhibitory peptide C46 effectively improved neurological function, reduced cerebral infarct volume and edema in tMCAO rats. Moreover, C46 mitigated BBB permeability, preserved the expression levels of TJ proteins, and suppressed the activation of MMPs in tMCAO rats and OGD/R-treated bEnd.3 cells. Meanwhile, C46 administration inhibited microglial activation and downregulated the expression of proinflammatory mediators both in vivo (tMCAO rats) and in vitro (OGD/R- or LPS-induced BV2 microglia).

Conclusion: 

eCypA, released by microglia and brain microvascular endothelial cells under ischemic–hypoxic and inflammatory conditions, serves as a critical pathogenic mediator that drives neuroinflammation and BBB disruption in AIS. Targeting eCypA with C46 peptide effectively abrogates these pathological cascades, thereby supporting eCypA as a novel therapeutic target for AIS.

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