Estevao C, Bowers CE, Luo D, Sarker M, Hoeh AE, Frudd K, Turowski P, Greenwood J. CCL4 induces inflammatory signalling and barrier disruption in the neurovascular endothelium.
Brain Behav Immun Health 2021;
18:100370. [PMID:
34755124 DOI:
10.1016/j.bbih.2021.100370]
[Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 10/13/2021] [Indexed: 12/27/2022] Open
Abstract
Background
During neuroinflammation many chemokines alter the function of the blood-brain barrier (BBB) that regulates the entry of macromolecules and immune cells into the brain. As the milieu of the brain is altered, biochemical and structural changes contribute to the pathogenesis of neuroinflammation and may impact on neurogenesis. The chemokine CCL4, previously known as MIP-1β, is upregulated in a wide variety of central nervous system disorders, including multiple sclerosis, where it is thought to play a key role in the neuroinflammatory process. However, the effect of CCL4 on BBB endothelial cells (ECs) is unknown.
Materials and methods
Expression and distribution of CCR5, phosphorylated p38, F-actin, zonula occludens-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin) were analysed in the human BBB EC line hCMEC/D3 by Western blot and/or immunofluorescence in the presence and absence of CCL4. Barrier modulation in response to CCL4 using hCMEC/D3 monolayers was assessed by measuring molecular flux of 70 kDa RITC-dextran and transendothelial lymphocyte migration. Permeability changes in response to CCL4 in vivo were measured by an occlusion technique in pial microvessels of Wistar rats and by fluorescein angiography in mouse retinae.
Results
CCR5, the receptor for CCL4, was expressed in hCMEC/D3 cells. CCL4 stimulation led to phosphorylation of p38 and the formation of actin stress fibres, both indicative of intracellular chemokine signalling. The distribution of junctional proteins was also altered in response to CCL4: junctional ZO-1 was reduced by circa 60% within 60 min. In addition, surface VE-cadherin was redistributed through internalisation. Consistent with these changes, CCL4 induced hyperpermeability in vitro and in vivo and increased transmigration of lymphocytes across monolayers of hCMEC/D3 cells.
Conclusion
These results show that CCL4 can modify BBB function and may contribute to disease pathogenesis.
The chemokine CCL4 induced phosphorylation of P38 in an in vitro model of the blood-brain barrier (BBB).
CCL4 treatment resulted in reduction of plasma membrane VE-cadherin and junctional ZO-1.
CCL4 induced neurovascular barrier breakdown in vitro and in vivo.
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