AT1 Receptor Antagonism Is Proangiogenic in the Brain: BDNF a Novel Mediator

Abstract

Candesartan is an angiotensin II type 1 receptor blocker (ARB) that has been to shown to limit ischemic stroke and improve stroke outcome. In experimental stroke, candesartan induces a proangiogenic effect that is partly attributable to vascular endothelial growth factor. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family that has been reported to have angiogenic effects and play an important role in recovery after stroke. The purpose of this investigation was to determine the role of BDNF in the proangiogenic effect of candesartan in the brain under hypertensive conditions. Accordingly, spontaneously hypertensive rats were treated with candesartan, and brain tissue samples were collected for quantification of BDNF expression. In addition, human cerebromicrovascular endothelial cells were treated with either low-dose (1 ƒM) or high-dose (1 mM) angiotensin II alone or in combination with candesartan (0.16 mM) to assess the effect of candesartan treatment and BDNF involvement in the behavior of endothelial cells. Candesartan significantly increased the expression of BDNF in the SHR (P , 0.05). In addition, candesartan reversed the antiangiogenic effect of the 1-mM dose of AngII (P 5 0.0001). The observed effects of candesartan were ablated by neutralizing the effects of BDNF. Treatment with the AT2 antagonist PD-123319 significantly reduced tube-like formation in endothelial cells. AT2 stimulation induced the BDNF expression and migration (P , 0.05). In conclusion, candesartan exerts a proangiogenic effect on brain microvascular endothelial cells treated with angiotensin II. This response is attributable to increased BDNF expression and is mediated through stimulation of the AT2 receptor.

Candesartan Induces a Prolonged Proangiogenic Effect and Augments Endothelium-Mediated Neuroprotection after Oxygen and Glucose Deprivation: Role of Vascular Endothelial Growth Factors A and B

“…We previously showed an enhanced proangiogenic state in vitro by candesartan treatment with or without exogenous angiotensin II treatment. Our recent work identified brain-derived neurotrophic factor as a mediator of this effect secondary to unopposed angiotensin II type 2 receptor stimulation (Alhusban et al, 2013). This study further supports our previous findings, because VEGF-A and brain-derived neurotrophic factor expression is interrelated (Chen et al, 2005;Li et al, 2006).…”

Clinically Relevant Doses of Candesartan Inhibit Growth of Prostate Tumor Xenografts In Vivo through Modulation of Tumor Angiogenesis

“…Cell migration assay (wound healing assay) was performed as described previously (Goc et al, 2012b;Alhusban et al, 2013). Briefly, PC3 cells were grown on 12-well plates to reach confluence (24 hours), and then scratches were made in the cell monolayers using 1-ml pipette tips followed by treatment with different concentrations of candesartan (0.5, 5, 10, 25, and 200 mM) in serum-free DMEM.…”

“…Mice were divided into two groups. The groups were subjected to intraperitoneal injections of candesartan (CV-11974 [see Alhusban et al, 2013] dissolved in 100 ml of 0.9% saline) at a dose of 6.5 mg/kg body weight every 24 hours for 18 days (treatment started 6 days after subcutaneous tumor injection when tumors of equal size were clearly visible), and the respective controls were injected intraperitoneally with 0.9% saline every 24 hours. CV-11974 is an activated form of candesartan that does not need to be activated by the liver, and hence can be readily used for both in vitro and in vivo experiments.…”

“…Anti-vascular endothelial growth factor (anti-VEGF) antibodies were purchased from Millipore (Billerica, MA). Primary antibodies against b-actin and laminin as well as AT2 receptor agonist (CGP-121141A; see Alhusban et al, 2013) were purchased from Sigma-Aldrich (St. Louis, MO). Primary antibodies against angiotensin II type 1 (AT1) and AT2 receptors were purchased from Abcam (Cambridge, MA).…”

“…This paradigm ignores AngII-independent effects of candesartan as well as the role of locally produced AngII, which has been well characterized in a variety of tissues and cell types (Reid et al, 2011;Angeli et al, 2013;Lu et al, 2013). Recently, candesartan was shown to be proangiogenic in cerebral microvascular endothelial cells via activation of the angiotensin II type 2 (AT2) receptor (Alhusban et al, 2013). This effect occurred even in the absence of exogenous AngII.…”