Submitted on June 19, 2007
Accepted on November 27, 2007
Lymphocytic microparticles inhibit angiogenesis by stimulating oxidative stress and negatively regulating VEGF-induced pathways
Chun Yang1, Bupe Rose Mwaikambo2, Tang Zhu3, Carmen Gagnon3, Josiane Lafleur4, Swathi Seshadri2, Pierre Lachapelle2, Jean-Claude Lavoie5, Sylvain Chemtob2, and Pierre Hardy3*
1 Biochemistry, university de montreal, montreal, Canada
2 Pharmacology and Therapeutics, McGill university, montreal, Canada
3 pharmacology, university de montreal, montreal, Canada
4 pharmacology, University de Montreal, Montreal, Canada
5 Laboratoire d'innovations biotechnologiques, University de Montreal, Montreal, Canada
* To whom correspondence should be addressed. E-mail: pierre.hardy{at}recherche-ste-justine.qc.ca.
Recent studies have demonstrated that lymphocyte-derived microparticles (LMPs) impair endothelial cell function. However, no data currently exists regarding the contribution of LMPs in the regulation of angiogenesis. In the present study, we investigated the effects of LMPs on angiogenesis in vivo and in vitro and demonstrate that LMPs strongly suppressed aortic ring microvessel sprouting and in vivo corneal neovascularization. In vitro, LMPs considerably diminished human umbilical vein endothelial cell (HUVEC) survival and proliferation in a concentration dependent manner. Mechanistically, the antioxidants U74389G and U83836E, were partially protective against the anti-proliferative effects of LMPs, while the NOX inhibitors, apocynin and diphenyleneiodonium (DPI), significantly abrogated these effects. Moreover, LMPs increased not only the expression of the NADPH oxidase (NOX) subunits gp91phox, p22phox, and p47phox, but also the production of reactive oxygen species (ROS) and NOX-derived superoxide (O2-). Of importance, LMPs caused a pronounced augmentation in the protein expression of the CD36 anti-angiogenic receptor, while significantly downregulating the protein levels of VEGFR2 and its downstream signaling mediator phosphorylated ERK 1/2. In summary, LMPs potently suppress neovascularization in vivo and in vitro by augmenting ROS generation via NOX and interfering with the VEGF signaling pathway.
