Brain Endothelial Cells Release Apical and Basolateral Microparticles in Response to Inflammatory Cytokine Stimulation: Relevance to Neuroinflammatory Stress?

Abstract

Microparticles (MP) are regarded both as biomarkers and mediators of many forms of pathology, including neurovascular inflammation. Here, we characterized vectorial release of apical and basolateral MPs (AMPs and BMPs) from control and TNF-α/IFN-γ treated human brain endothelial monolayers, studied molecular composition of AMPs and BMPs and characterized molecular pathways regulating AMP and BMP release. The effects of AMPs and BMPs on blood-brain barrier properties and human brain microvascular smooth muscle tonic contractility in vitro were also evaluated. We report that human brain microvascular endothelial cells release MPs both apically and basolaterally with both AMP and BMP release significantly increased following inflammatory cytokine challenge (3.5-fold and 3.9-fold vs. control, respectively). AMPs and BMPs both carry proteins derived from parent cells including those in BBB junctions (Claudin−1, −3, −5, occludin, VE-cadherin). AMPs and BMPs represent distinct populations whose release appears to be regulated by distinctly separate molecular pathways, which depend on signaling from Rho-associated, coiled-coil containing protein kinase (ROCK), calpain as well as cholesterol depletion. AMPs and BMPs modulate functions of neighboring cells including BBB endothelial solute permeability and brain vascular smooth muscle contractility. While control AMPs enhanced brain endothelial barrier, cytokine-induced AMPs impaired BBB. Cytokine-induced but not control BMPs significantly impaired human brain smooth muscle contractility as early as day 1. Taken together these results indicate that AMPs and BMPs may contribute to neurovascular inflammatory disease progression both within the circulation (AMP) and in the brain parenchyma (BMP).

Human placental mesenchymal stem cells improve stroke outcomes via extracellular vesicles-mediated preservation of cerebral blood flow

“…This agrees with studies suggesting that stem cell derived EVs account for paracrine benefits of SCT in stroke [ 12 , [51] , [52] , [53] ]. By depleting membrane cholesterol and disrupting lipid rafts [ 22 , 23 , 25 ], MβCD inhibits formation and release of EVs. Consequently, cholesterol availability may be an important co-factor needed to generate hPMSC-EVs in stroke protection [55] .…”

“…EVs were isolated as described [25] . Briefly, culture media were collected from confluent hPMSCs 48 h after applying fresh medium.…”

Pathophysiology of blood brain barrier dysfunction during chronic cerebral hypoperfusion in vascular cognitive impairment

“…These cytokines bind to their receptors on endothelial cells to induce various signaling cascades including the recruitment of extracellular signal-regulated kinases (Erk1/2) 188 . TNF and IFN-γ synergistically increase chemokine secretion in CNS inflammation 189 , and also stimulate the release of microparticles, cell membrane-derived particles generated by budding from the endothelial cell surface 190 . These microparticles export TJs and AJs away from the transendothelial surface following cytokine stimulation, thus contributing to the loss of the barrier property of the BBB 190 .…”

Amyloid Beta Peptides and Th1 Cytokines Modulate Human Brain Vascular Smooth Muscle Tonic Contractile Capacity In Vitro: Relevance to Alzheimer’s Disease?

“…Further, cerebrovascular dysfunction has been shown to occur in AD long before the onset of AD symptoms [ 16 ]. Changes in cerebral blood flow have been implicated as a strong predictive factor in AD [ 12 , 17 , 18 ]. A novel model of decreased cerebral blood flow in mice recently demonstrated the increased production and deposition of Aβ on cerebral blood vessels and in the brain [ 19 ], suggesting that cerebrovascular disturbances play an important role in the progression of AD.…”