CLEC14A deficiency exacerbates neuronal loss by increasing blood-brain barrier permeability and inflammation

Abstract

Background: Ischemic stroke is a main cause of mortality. Blood-brain barrier (BBB) breakdown appears to play a critical role in inflammation in patients with ischemic stroke and acceleration of brain injury. The BBB has a protective function and is composed of endothelial cells, pericytes, and astrocytes. In ischemic stroke treatments, regulation of vascular endothelial growth factor (VEGF)-A and vascular endothelial growth factor receptor (VEGFR)-2 is a crucial target despite adverse effects. Our previous study found that loss of C-type lectin family 14 member A (CLEC14A) activated VEGF-A/VEGFR-2 signaling in developmental and tumoral angiogenesis. Here, we evaluate the effects of BBB impairment caused by CLEC14A deficiency in ischemia-reperfusion injury. Methods: In vitro fluorescein isothiocyanate (FITC)-dextran permeability, transendothelial electrical resistance (TEER) assay, and immunostaining were used to evaluate endothelial integrity. BBB permeability was assessed using Evans blue dye and FITC-dextran injection in Clec14a −/− (CLEC14A-KO) mice and wild-type mice. Middle cerebral artery occlusion surgery and behavioral assessments were performed to evaluate the neurologic damage. The change of tight junctional proteins, adhesion molecules, pro-inflammatory cytokines, and microglial were confirmed by immunofluorescence staining, Western blotting, and quantitative reverse transcription polymerase chain reaction of brain samples. Results: In endothelial cells, knockdown of CLEC14A increased FITC-dextran permeability and decreased transendothelial electrical resistance; the severity of this effect increased with VEGF treatment. Immunofluorescence staining revealed that tight junctional proteins were attenuated in the CLEC14A knockdown endothelial cells. Consistent with the in vitro results, CLEC14A-KO mice that were injected with Evans blue dye had cerebral vascular leakage at postnatal day 8; wild-type mice had no leakage. We used a middle cerebral artery occlusion model and found that CLEC14A-KO mice had severe infarcted brain and neurological deficits with upregulated VEGFR-2 expression. FITC-dextran leakage was present in CLEC14A-KO mice after ischemia-reperfusion, and the numbers of tight junctional molecules were significantly decreased. Loss of CLEC14A increased the pro-inflammatory response through adhesion molecule expression, and glial cells were activated. Conclusions: These results suggest that activation of VEGFR-2 in CLEC14A-KO mice aggravates ischemic stroke by exacerbating cerebral vascular leakage and increasing neuronal inflammation after ischemia-reperfusion injury.

CLEC14A protects against podocyte injury in mice with adriamycin nephropathy

“…We found that podocyte injury was further exacerbated in Clec14a knockout mice than those in control mice with ADR nephropathy. Moreover, CLEC14A deficiency exacerbated macrophage infiltration and inflammatory responses in the kidney from mice with ADR nephropathy in consistent with previous studies showing that the loss of CLEC14A increased inflammatory responses through adhesion molecule expression and glial cells activation in cerebral ischemia‐reperfusion injury 24 . Collectively, we conclude that CLEC14A as a central target molecule protects against podocyte injury.…”

Inflammation and Rho-Associated Protein Kinase-Induced Brain Changes in Vascular Dementia

“…The BBB is required for the structural stabilization of TJ proteins as structural com-ponents that maintain cerebrovascular integrity and BBB function [ 54 , 55 ]. Activated ROCK and pro-inflammatory cytokines correspond to vascular endothelial damage [ 51 , 56 ]. We found an inflammatory response that was upregulated by higher vascular permeability in the ischemic-injured brains of the VD group ( Figure 8 A–E).…”

Coicis semen protects against focal cerebral ischemia-reperfusion injury by inhibiting oxidative stress and promoting angiogenesis via the TGFβ/ALK1/Smad1/5 signaling pathway

“…Stroke is a major cause of disability and death worldwide, but the agents currently used to treat stroke are not sufficient to effectively improve the recovery of stroke patients [ 25 , 26 ]. Coicis Semen, a traditional Chinese medicine, exerts antioxidant and anti-inflammatory effects in many diseases, including coronary heart disease [ 27 ], systemic inflammatory disease [ 28 ], and cancer [ 9 , 29 ].…”