Microparticle-associated endothelial protein C receptor and the induction of cytoprotective and anti-inflammatory effects

Abstract

The online version of this article contains a supplementary appendix. BackgroundThe endothelial protein C receptor plays an important role within the protein C pathway in regulating coagulation and inflammation. Recently, we described that endothelial protein C receptor can be released in vitro in microparticulate form from primary endothelial cells by exogenous activated protein C. Activated protein C bound to this endothelial protein C receptor retains anticoagulant activity and we hypothesize that this microparticulate endothelial protein C receptor-activated protein C complex can also cleave endothelial protease-activated receptor 1 to modulate inflammation and increase cell survival. Our main objective was, therefore, to study the effect that microparticle-associated endothelial protein C receptor-activated protein C has on endothelial function. Design and MethodsMini-arrays were used and probed with cDNA obtained from endothelial cells after treatment with microparticle-associated endothelial protein C receptor-activated protein C and results were confirmed by real time polymerase chain reaction. The functional relevance of changes at gene level were further analyzed by endothelial apoptosis and permeability assays, in the presence and absence of specific blockade of endothelial protein C receptor, protein C and protease-activated receptor 1. ResultsGene profiling of endothelial cells stimulated by 40 nmol/L activated protein C on microparticles showed significant changes in anti-apoptotic and inflammatory pathways. This was accompanied by protease-activated receptor 1-dependent anti-apoptotic and barrier protective effects, the latter of which also involved sphingosine 1-phosphate receptor and vascular endothelial growth factor receptor-2/ kinase insert domain receptor. Protein C blockade reversed these effects showing specificity for activated protein C on microparticles. Furthermore, confocal microscopy and enzyme-linked immunosorbent assay of plasma obtained from septic patients during recombinant activated protein C treatment showed evidence of their presence in vivo. ConclusionsActivated protein C on microparticle-associated endothelial protein C receptor release can induce protease-activated receptor 1-dependent endothelial effects. The mechanisms underlying barrier protection involve sphingosine 1-phosphate receptor and kinase insert domain receptor.Key words: activated protein C, endothelial protein C receptor, microparticles, protease activated receptor, vascular endothelial growth factor receptor-2.Citation: Pérez-Casal M, Downey C, Cutillas-Moreno B, Zuzel M, Fukudome K, and Toh CH. Microparticle-associated endothelial protein C receptor and the induction of cytoprotective and antiinflammatory effects. Haematologica 2009; 94:387-394. doi:10.3324/haematol.13547 ©2009 Ferrata Storti Foundation. This is an open-access paper. Microparticle-associated endothelial protein C receptor and the induction of cytoprotective and anti-inflammatory effects

Altered profile of circulating microparticles in rheumatoid arthritis patients

“…Actually, some groups revealed anticoagulant and protective effects of some MP subsets [50][51][52], in contrast with the procoagulant and deleterious results reported by others [10,27,45,48,53]. Interestingly, these diverse effects could be attributed to the exposure of different mediators, such as activated protein C, tissue factor or von Willebrand factor among MP subsets.…”

Microparticles in endothelial cell and vascular homeostasis: are they really noxious?

“…The detection of elevated circulating APC + -microparticles levels measured by Pérez-Cazal et al in patients with sepsis after treatment by rhAPC reinforces this hypothesis. 3 Other confirmation was provided by Bouchama et al, using a baboon heatstroke model. 31 They investigated whether the antithrombotic and cytoprotective effect of rhAPC could protect baboons from fatal heatstroke.…”

“…30 Altogether, these data underline the paradigm of microparticles as potent conveyors of APC exerting cytoprotective activities. 3 Although results obtained from in vitro models are difficult to translate/extrapolate to clinical settings, these observations shed new light on the pathophysiological relevance of microparticles as modulators of the pro-to anti-inflammatory balance. The detection of elevated circulating APC + -microparticles levels measured by Pérez-Cazal et al in patients with sepsis after treatment by rhAPC reinforces this hypothesis.…”

“…16 In this issue of the journal, Pérez-Casal et al provide evidence that part of the cytoprotective effects of APC are mediated by microparticles harboring EPCR, therefore able to bind APC, termed APC + -microparticles. 3 A variety of cytoprotective properties of APC, namely: (i) alteration of genes profiles, (ii) modulation of cytokine or cytoadhesin transcription levels, (iii) anti-apoptotic activity, and (iv) endothelial barrier stabilization, could be mimicked in vitro by APC + -microparticles. 30 Gene profiling of endothelial cells stimulated by APC + -microparticles showed significant changes in anti-apoptotic and anti-inflammatory patterns.…”

Coagulation and the Vessel Wall in Pulmonary Embolism

“…34 EMPs from activated cells triggered TF-dependent thrombin formation in vitro and thrombus formation in vivo in a rat venous stasis model. 35 However, EMPs can also expose endothelial protein C receptor and exhibit anticoagulant properties, 36,37 suggesting that EMPs participate in the tuning of the pro-/anticoagulant equilibrium. EMPs induce proliferation of ECs and inhibit apoptosis of ECs, presenting vascular protective effects.…”