End-organ protection in hypertension by the novel and selective Rho-kinase inhibitor, SAR407899

Abstract

Aim: To compare the therapeutic efficacy of SAR407899 with the current standard treatment for hypertension [an angiotensin converting enzyme (ACE)-inhibitor and a calcium channel blocker] and compare the frequency and severity of the hypertension-related end-organ damage.

Methods: Long-term pharmacological characte-rization of SAR407899 has been performed in two animal models of hypertension, of which one is sensitive to ACE-inhibition (LNAME) and the other is insensitive [deoxycorticosterone acetate (DOCA)]. SAR407899 efficiently lowered high blood pressure and significantly reduced late-stage end organ damage as indicated by improved heart, kidney and endothelial function and reduced heart and kidney fibrosis in both models of chronic hypertension.

Results: Long term treatment with SAR407899 has been well tolerated and dose-dependently reduced elevated blood pressure in both models with no signs of tachyphylaxia. Blood pressure lowering effects and protective effects on hypertension related end organ damage of SAR407899 were superior to ramipril and amlodipine in the DOCA rat. Typical end-organ damage was significantly reduced in the SAR407899-treated animals. Chronic administration of SAR407899 significantly reduced albuminuria in both models. The beneficial effect of SAR407899 was associated with a reduction in leukocyte/macrophage tissue infiltration. The overall protective effect of SAR407899 was superior or comparable to that of ACE-inhibition or calcium channel blockade. Chronic application of SAR407899 protects against hypertension and hypertension-induced end organ damage, regardless of the pathophysiological mechanism of hypertension.

Conclusion: Rho-kinases-inhibition by the SAR407899 represents a new therapeutic option for the treatment of hypertension and its complications.

Keywords: Angiotensin converting enzyme-inhibition; End organ damage; Hypertension; Rho-kinase.

Figure 1

Effect of SAR407899 on body weight in deoxycorticosterone acetate and Nω-Nitro-L-arginine methyl ester hydrochloride hypertensive animals. A and B: Body weight of deoxycorticosterone acetate (DOCA) rats. A significant decrease in body weight was observed after 28 d; A: Effect of SAR407899 at 3 mg/kg and 10 mg/kg on body weight. Both doses protected DOCA rats against body weight loss; B: Effect of ramipril at 1 mg/kg and amlodipine at 3 mg/kg on body weight. Only amlodipine showed protective effects on body weight loss; C and D: Body weight of Nω-Nitro-L-arginine methyl ester hydrochloride (LNAME) rats. A significant decrease in body weight was observed after 22 d. C: SAR407899 at 10 mg/kg significantly protected LNAME rats from body weight loss; D: Effect of ramipril at 1 mg/kg and amlodipine at 3 mg/kg on body weight. Only ramipril showed significant protective effects on body weight loss.

Figure 2

SAR407899 efficiently lowers blood pressure, proteinuria and mortality in hypertensive rats. Invasive measurement of blood pressure in deoxycorticosterone acetate (DOCA) (A) and in Nω-Nitro-L-arginine methyl ester hydrochloride (LNAME) (B) rats. At the given dose, SAR407899 showed superior blood pressure lowering effect in comparison to ramipril and amlodipine in both animal models; C and D: Assessment of kidney function in DOCA and LNAME rats. SAR407899 showed significant protective effects on the kidneys in both models, whereas ramipril reduced albuminuria only in the LNAME model. Amlodipine had no therapeutic effect on kidney in either model.

Figure 3

Effect of SAR407899 on heart and endothelial function. Measurement of heart function of isolated hearts of deoxycorticosterone acetate (DOCA) (A) and Nω-Nitro-L-arginine methyl ester hydrochloride (LNAME)-treated rats (B). SAR407899 showed a significant improvement of heart function compared to reference substances at both doses and in both models; C and D: Measurement of endothelial function of aortas of DOCA rats treated with SAR407899 (C) or with reference substances (D). Ramipril treatment had no effect on endothelial function. Long-term treatment with SAR407899 improved endothelial function in a dose-dependent fashion. Amlodipine had similar protective effects as SAR407899.

Figure 4

Histological examination of the effect of SAR407899 on the heart. Sirius red staining of hearts of deoxycorticosterone acetate (DOCA) (A-C) and Nω-Nitro-L-arginine methyl ester hydrochloride (LNAME) rats (G-I) showed a strong induction of myocardial fibrosis. Upon treatment with SAR407899 at 10 mg/kg, significant protective effects were observed. Haematoxylin eosin staining of hearts of DOCA (D-F) and LNAME rats (J-L) showed perivascular fibrosis, massive infiltration of leukocytes into the interstitium and sclerotic changes. SAR407899 treatment at 10 mg/kg attenuated multifocal fibrosis, perivascular fibrosis and leukocyte infiltration. M and N: Summary of heart lesions and the effect of SAR407899 and reference substances in DOCA (M) and LNAME rats (N). A, D, G, J: Control; B, E: DOCA; H, K: LNAME; C, F, I, L: SAR407899 10 mg/kg.

Figure 5

Histological examination of the effect of SAR407899 on the kidney. A-C: Haematoxylin eosin staining of normal glomeruli in control rats (left), sclerotic changes, dilation and hypertrophy of glomeruli of deoxycorticosterone acetate (DOCA) rats (center) and protective effects of SAR407899 at 10 mg/kg (right); D-F: Podocin staining in kidneys. Upon DOCA treatment, massive loss of podocytes can be detected. SAR407899 at 10 mg/kg exerts a protective effect in the kidneys of DOCA rats and rescues podocytes; G-I: Haematoxylin eosin staining of normal glomeruli in control rats (left), severe fibrotic changes, infiltration of leukocytes, and hypertrophy of glomeruli of Nω-Nitro-L-arginine methyl ester hydrochloride (LNAME) rats (center), protective effects of SAR407899 at 10 mg/kg (right); J-L: Loss of podocytes upon LNAME treatment. SAR407899 at 10 mg/kg protected against loss of podocytes. Summary of kidney lesions and effect of SAR407899 and reference substances in DOCA (M) and LNAME rats (N). A, D, G, J: Control; B, E: DOCA; H, K: LNAME; C, F, I, L: SAR407899 10 mg/kg.

Figure 6

Effect of SAR407899 on the expression of fibrotic and leukocyte genes in the kidney. Determination of collagen, T cell (CD3) and macrophage (CD68) expression in the kidneys of deoxycorticosterone acetate (DOCA) (A, C and E) and Nω-Nitro-L-arginine methyl ester hydrochloride (LNAME) (B, D and F) rats. Expression of collagen was significantly increased upon DOCA and LNAME treatment. Upon DOCA or LNAME treatment, CD3 and CD68 abundance was induced, indicating that leukocytes infiltrated into the kidneys. SAR407899 treatment reduced expression of collagen and leukocyte genes in both models.