Tumour necrosis factor-α-mediated disruption of cerebrovascular endothelial barrier integrity in vitro involves the production of proinflammatory interleukin-6.
The co-involvement of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) during blood-brain barrier (BBB) injury has been reported in various models of neuroinflammation, although the precise functional interplay between these archetypal proinflammatory cytokines remains largely undefined within this context. In the current paper, we tested the hypothesis that TNF-α-mediated BBB disruption is measurably attributable in-part to induction of microvascular endothelial IL-6 production. In initial experiments, we observed that treatment of human brain microvascular endothelial cells (HBMvECs) with TNF-α (0-100 ng/mL, 0-24 h) robustly elicited both time- and dose-dependent induction of IL-6 expression and release, as well as expression of the IL-6 family receptor, GP130. Further experiments demonstrated that the TNF-α-dependent generation of reactive oxygen species, down-regulation of adherens/tight junction proteins, and concomitant elevation of HBMvEC permeability, were all significantly attenuated by blockade of IL-6 signalling using either an anti-IL-6 neutralizing antibody or an IL-6 siRNA. Based on these observations, we conclude that TNF-α treatment of HBMvECs in vitro activates IL-6 production and signalling, events that were shown to synergize with TNF-α actions to elicit HBMvEC permeabilization. These novel findings offer a constructive insight into the specific contribution of downstream cytokine induction to the injurious actions of TNF-α at the BBB microvascular endothelium interface. The co-involvement of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) during blood-brain barrier (BBB) injury has been widely reported. Using human brain microvascular endothelial cells (HBMvEC), we show that TNF-α-mediated BBB disruption is measurably attributable in-part to induction of endothelial IL-6 production and signalling. We demonstrate that the TNF-α-dependent generation of reactive oxygen species (ROS), down-regulation of interendothelial junctions, and concomitant elevation of HBMvEC permeability, could be significantly attenuated by using either an IL-6 neutralizing antibody or an IL-6-specific siRNA. These findings provide insight into the complex nature of proinflammatory cytokine injury at the BBB microvascular endothelium interface.
School of Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.
Keith D
KD
Rochfort
School of Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.
Laura E
LE
Collins
School of Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.
Alisha
A
McLoughlin
School of Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland.|Centre for Preventive Medicine, Dublin City University, Glasnevin, Dublin, Ireland.
Philip M
PM
Cummins
D000704:Analysis of Variance; D000906:Antibodies / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D002199:Capillary Permeability / Q000187:drug effects*; D062507:Claudin-5 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects*; D004727:Endothelium / Q000166:cytology; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015850:Interleukin-6 / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*; D062826:Zonula Occludens-1 Protein / Q000378:metabolism; D000099152:Cadherin 5
D000906:Antibodies; D015703:Antigens, CD; D015820:Cadherins; D062507:Claudin-5; D015850:Interleukin-6; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D062826:Zonula Occludens-1 Protein; D000099152:Cadherin 5; C569042:TJP1 protein, human
IL-6; TNF-α; blood-brain barrier; endothelial; reactive oxygen species