HDL Cholesterol Story Is Dead: Long Live HDL!

VEGFR2 is activated by high-density lipoproteins and plays a key role in the proangiogenic action of HDL in ischemia

High-density lipoproteins augment hypoxia-induced angiogenesis by inducing the key angiogenic vascular endothelial growth factor A (VEGFA) and total protein levels of its receptor 2 (VEGFR2). The activation/phosphorylation of VEGFR2 is critical for mediating downstream, angiogenic signaling events. This study aimed to determine whether reconstituted high-density lipoprotein (rHDL) activates VEGFR2 phosphorylation and the downstream signaling events and the importance of VEGFR2 in the proangiogenic effects of rHDL in hypoxia. In vitro, rHDL increased VEGFR2 activation and enhanced phosphorylation of downstream, angiogenic signaling proteins ERK1/2 and p38 MAPK in hypoxia. Incubation with a VEGFR2-neutralizing antibody attenuated rHDL-induced phosphorylation of VEGFR2, ERK1/2, p38 MAPK, and tubule formation. In a murine model of ischemia-driven neovascularization, rHDL infusions enhanced blood perfusion and augmented capillary and arteriolar density. Infusion of a VEGFR2-neutralizing antibody ablated those proangiogenic effects of rHDL. Circulating Sca1⁺/CXCR4⁺ angiogenic progenitor cell levels, important for neovascularization in response to ischemia, were higher in rHDL-infused mice 3 d after ischemic induction, but that did not occur in mice that also received the VEGFR2-neutralizing antibody. In summary, VEGFR2 has a key role in the proangiogenic effects of rHDL in hypoxia/ischemia. These findings have therapeutic implications for angiogenic diseases associated with an impaired response to tissue ischemia.-Cannizzo, C. M., Adonopulos, A. A., Solly, E. L., Ridiandries, A., Vanags, L. Z., Mulangala, J., Yuen, S. C. G., Tsatralis, T., Henriquez, R., Robertson, S., Nicholls, S. J., Di Bartolo, B. A., Ng, M. K. C., Lam, Y. T., Bursill, C. A., Tan, J. T. M. VEGFR2 is activated by high-density lipoproteins and plays a key role in the proangiogenic action of HDL in ischemia.

Diabetes and dyslipidemia: characterizing lipoprotein metabolism

Premature atherosclerosis in diabetes accounts for much of the decreased life span. New treatments have reduced this risk considerably. This review explores the relationship among the disturbances in glucose, lipid, and bile salt metabolic pathways that occur in diabetes. In particular, excess nutrient intake and starvation have major metabolic effects, which have allowed us new insights into the disturbance that occurs in diabetes. Metabolic regulators such as the forkhead transcription factors, the farnesyl X transcription factors, and the fibroblast growth factors have become important players in our understanding of the dysregulation of metabolism in diabetes and overnutrition. The disturbed regulation of lipoprotein metabolism in both the intestine and the liver has been more clearly defined over the past few years, and the atherogenicity of the triglyceride-rich lipoproteins, and - in tandem - low levels of high-density lipoproteins, is seen now as very important. New information on the apolipoproteins that control lipoprotein lipase activity has been obtained. This is an exciting time in the battle to defeat diabetic atherosclerosis.