title: C5a induces caspase-dependent apoptosis in brain vascular endothelial cells in experimental lupus.
abstract: Blood-brain barrier (BBB) dysfunction complicates central nervous system lupus, an important aspect of systemic lupus erythematosus. To gain insight into the underlying mechanism, vascular corrosion casts of brain were generated from the lupus mouse model, MRL/lpr mice and the MRL/MpJ congenic controls. Scanning electron microscopy of the casts showed loss of vascular endothelial cells in lupus mice compared with controls. Immunostaining revealed a significant increase in caspase 3 expression in the brain vascular endothelial cells, which suggests that apoptosis could be an important mechanism causing cell loss, and thereby loss of BBB integrity. Complement activation occurs in lupus resulting in increased generation of circulating C5a, which caused the endothelial layer to become 'leaky'. In this study, we show that C5a and lupus serum induced apoptosis in cultured human brain microvascular endothelial cells (HBMVECs), whereas selective C5a receptor 1 (C5aR1) antagonist reduced apoptosis in these cells, demonstrating C5a/C5aR1-dependence. Gene expression of initiator caspases, caspase 1 and caspase 8, and pro-apoptotic proteins death-associated protein kinase 1, Fas-associated protein (FADD), cell death-inducing DNA fragmentation factor 45 000 MW subunit A-like effector B (CIDEB) and BCL2-associated X protein were increased in HBMVECs treated with lupus serum or C5a, indicating that both the intrinsic and extrinsic apoptotic pathways could be critical mediators of brain endothelial cell apoptosis in this setting. Overall, our findings suggest that C5a/C5aR1 signalling induces apoptosis through activation of FADD, caspase 8/3 and CIDEB in brain endothelial cells in lupus. Further elucidation of the underlying apoptotic mechanisms mediating the reduced endothelial cell number is important in establishing the potential therapeutic effectiveness of C5aR1 inhibition that could prevent and/or reduce BBB alterations and preserve the physiological function of BBB in central nervous system lupus.
authors.affiliation: Department of Medicine, University at Buffalo, Buffalo, NY, USA.
authors.forename: Supriya D
authors.initials: SD
authors.lastname: Mahajan
authors.affiliation: Toshiba Vascular Stroke Center, Biomedical Engineering Department, University at Buffalo, Buffalo, NY, USA.
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Tutino
authors.affiliation: Department of Medicine, University at Buffalo, Buffalo, NY, USA.
authors.forename: Yonas
authors.initials: Y
authors.lastname: Redae
authors.affiliation: Toshiba Vascular Stroke Center, Biomedical Engineering Department, University at Buffalo, Buffalo, NY, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Meng
authors.affiliation: Toshiba Vascular Stroke Center, Biomedical Engineering Department, University at Buffalo, Buffalo, NY, USA.
authors.forename: Adnan
authors.initials: A
authors.lastname: Siddiqui
authors.affiliation: School of Biomedical Sciences, University of Queensland, St Lucia, QLD, Australia.
authors.forename: Trent M
authors.initials: TM
authors.lastname: Woodruff
authors.affiliation: Department of Pediatrics, University at Buffalo, Buffalo, NY, USA.
authors.forename: James N
authors.initials: JN
authors.lastname: Jarvis
authors.affiliation: Department of Pediatrics, University at Buffalo, Buffalo, NY, USA.
authors.forename: Teresa
authors.initials: T
authors.lastname: Hennon
authors.affiliation: Department of Medicine, University at Buffalo, Buffalo, NY, USA.
authors.forename: Stanley
authors.initials: S
authors.lastname: Schwartz
authors.affiliation: Department of Medicine, University at Buffalo, Buffalo, NY, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Quigg
authors.affiliation: Department of Medicine, University at Buffalo, Buffalo, NY, USA.
authors.forename: Jessy J
authors.initials: JJ
authors.lastname: Alexander
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D015936:Complement C5a / Q000378:metabolism*; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism*; D006801:Humans; D020945:Lupus Vasculitis, Central Nervous System / Q000276:immunology*; D051379:Mice; D019463:Mice, Inbred MRL lpr; D010456:Peptides, Cyclic / Q000494:pharmacology; D044087:Receptor, Anaphylatoxin C5a / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C438957:AcPhe(ornithine-Pro-cyclohexylamine-Trp-Arg); D051017:Apoptosis Regulatory Proteins; C488033:C5AR1 protein, human; C112511:CIDEB protein, human; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D010456:Peptides, Cyclic; D044087:Receptor, Anaphylatoxin C5a; D015936:Complement C5a; D053148:Caspase 3
keywords: apoptosis; blood-brain barrier; complement; endothelial cells; neurodegeneration