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Chemokine receptors as novel pharmacological targets to reduce blood pressure during experimental hypertension in mice

C.T. Chan, J.P. Moore, K. Budzyn, A. Vinh, T.M. De Silva, E.S. Jones, C.G. Sobey and G.R. Drummond, Vascular Biology & Immunopharmacology Group, Department of Pharmacology, Monash University, Clayton, VIC 3800, Australia.

Introduction: Leukocyte infiltration into the artery wall plays a pathophysiological role in hypertension by promoting vascular inflammation and endothelial dysfunction (Guzik et al., 2007). Chemokines are chemoattractant cytokines that bind to receptors expressed on leukocytes and thereby promote their migration into tissues.

Aims: To identify chemokine receptors that are upregulated in the vascular wall during deoxycorticosterone acetate (DOCA)/salt-induced hypertension in mice and to evaluate the impact of pharmacological inhibition of these receptors on systolic BP.

Methods: Hypertension was induced in C57Bl6/J mice by DOCA/salt treatment as previously described (Guzik et al., 2007). Some DOCA/salt-treated animals received daily i.p. injections of either the CCR2 antagonist, INCB3344 (30 mg/kg/d) or vehicle (10% DMSO/0.9% carboxymethylcellulose) from days 10-21. Systolic BP was monitored by tail cuff and aortas were removed after 21 d for measurement of chemokine receptor expression by real-time RT-PCR.

Results: DOCA/salt-treated mice had markedly higher systolic BP (158±2 mmHg) than sham-treated animals (114±5 mmHg; P<0.0001; n11). A preliminary RT-PCR screen of a gene panel containing 20 chemokine receptors indicated an increase in mRNA expression of CCR2 in aortas from DOCA/salt-treated mice (n=3). Taqman® real-time PCR confirmed this increase in CCR2 expression (by 2.2-fold), and also revealed elevated expression of the CCR2 ligands CCL2 (2.3-fold), CCL7 (4.0-fold), CCL8 (2.8-fold) and CCL12 (4.2-fold) in DOCA/salt-treated mice (n=7 for all genes; P<0.05). INCB3344-treatment blunted DOCA/salt-induced increases in aortic expression of CCR2 and CCL2 by 55% and 45%, respectively (n=6-8, P<0.05) but did not alter CCL7, CCL8 and CCL12 levels. DOCA/salt-induced elevations in systolic BP were also reversed by INCB3344 (by 15 mmHg; n=11, P<0.01) whereas the vehicle had no effect (n=10).

Discussion: Thus CCR2 represents a promising therapeutic target to reduce BP in hypertension. Future studies will examine if the anti-hypertensive effects of INCB3344 involve inhibition of pro-inflammatory leukocyte migration into the vascular wall.

Guzik TJ, Hoch NE, Brown KA, McCann LA, Rahman A, Dikalov S, Goronzy J, Weyand C, Harrison DG. (2007) Journal of Experimantal Medicine 204: 2449-2460.