Selective activation of peroxisome proliferator-activated receptor (PPAR)alpha and PPAR gamma induces neoangiogenesis through a vascular endothelial growth factor-dependent mechanism.
OBJECTIVE
Peroxisome proliferator-activated receptors (PPARs) are therapeutic targets for fibrates and thiazolidinediones, which are commonly used to ameliorate hyperlipidemia and hyperglycemia in type 2 diabetes. In this study, we evaluated whether activation of PPAR alpha and PPAR gamma stimulates neoangiogenesis.


METHODS
We used selective synthetic PPAR alpha and PPAR gamma agonists and investigated their angiogenic potentials in vitro and in vivo.


RESULTS
Activation of PPAR alpha and PPAR gamma leads to endothelial tube formation in an endothelial/interstitial cell co-culture assay. This effect is associated with increased production of the angiogenic cytokine vascular endothelial growth factor (VEGF). Neovascularization also occurs in vivo, when PPAR alpha and PPAR gamma agonists are used in the murine corneal angiogenic model. No vascular growth is detectable when PPAR alpha and PPAR gamma agonists are respectively used in PPAR alpha knockout mice and mice treated with a specific PPAR gamma inhibitor, demonstrating that this angiogenic response is PPAR mediated. PPAR alpha- and PPAR gamma-induced angiogenesis is associated with local VEGF production and does not differ in extent and morphology from that induced by VEGF. In addition, PPAR alpha- and PPAR gamma-induced in vitro and in vivo angiogenesis may be significantly decreased by inhibiting VEGF activity. Finally, in corneas treated with PPAR alpha and PPAR gamma agonists, there is increased phosphorylation of endothelial nitric oxide synthase and Akt.


CONCLUSIONS
These findings demonstrate that PPAR alpha and PPAR gamma activation stimulates neoangiogenesis through a VEGF-dependent mechanism. Neoangiogenesis is a crucial pathological event in type 2 diabetes. The ability of PPAR alpha and PPAR gamma agonists to induce neoangiogenesis might have important implications for the clinical and therapeutic management of type 2 diabetes.
Biscetti
Federico
F
Laboratory of Vascular Biology and Genetics, Department of Medicine, A. Gemelli University Hospital, Catholic University School of Medicine, Rome, Italy.
Gaetani
Eleonora
E
Flex
Andrea
A
Aprahamian
Tamar
T
Hopkins
Teresa
T
Straface
Giuseppe
G
Pecorini
Giovanni
G
Stigliano
Egidio
E
Smith
Roy C
RC
Angelini
Flavia
F
Castellot
John J
JJ
Pola
Roberto
R
D002455:Cell Division / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D018920:Coculture Techniques; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D018919:Neovascularization, Physiologic / Q000187:drug effects; D047493:PPAR alpha / Q000502:physiology*; D047495:PPAR gamma / Q000502:physiology*; D013498:Suramin / Q000494:pharmacology; D014471:Umbilical Veins / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
D047493:PPAR alpha; D047495:PPAR gamma; D042461:Vascular Endothelial Growth Factor A; D013498:Suramin