Renal protective effects of N-acetyl-Ser-Asp-Lys-Pro in deoxycorticosterone acetate-salt hypertensive mice

Background Hypertension-induced renal injury is characterized by inflammation, fibrosis and proteinuria. Previous studies have demonstrated that N-acetyl-Ser-Asp-Lys-Pro (Ac-SDKP) inhibits renal damage following diabetes mellitus and antiglomerular basement membrane nephritis. However, its effects on low-renin hypertensive nephropathy are not known. Thus, we hypothesized that AcSDKP has renal protective effects on deoxycorticosterone acetate (DOCA)-salt hypertensive mice, decreasing inflammatory cell infiltration, matrix deposition and albuminuria. Method We uninephrectomized 16-week-old C57BL/6J mice and treated them with either placebo, DCOA (10 mg/10 g body weight subcutaneous) and 1% sodium chloride with 0.2% potassium chloride in drinking water (DOCA-salt) or DOCA-salt with Ac-SDKP (800 mu g/kg per day) for 12 weeks. We measured blood pressure, urine albumin, glomerular matrix, renal collagen content, monocyte/macrophage infiltration and glomerular nephrin expression. Results Treatment with DOCA-salt significantly increased blood pressure (P<0.01), which remained unaltered by AcSDKP. Ac-SDKP decreased DOCA-salt-induced renal collagen deposition, glomerular matrix expansion and monocyte/macrophage infiltration. Moreover, DOCA-salt-induced increase in albuminuria was normalized by AcSDKP (controls, 10.8 +/- 1.7; DOCA-salt, 41 +/- 5; DOCA-salt+Ac-SDKP, 13 +/- 3 mu g/10 g body weight per 24 h; P<0.001, DOCA-salt vs. DOCA-salt+Ac-SDKP). Loss of nephrin reportedly causes excess urinary protein excretion; therefore, we determined whether Ac-SDKP inhibits proteinuria by restoring nephrin expression in the glomerulus of hypertensive mice. DOCA-salt significantly downregulated glomerular nephrin expression (controls, 37 +/- 8; DOCA-salt, 10 +/- 1.5% of glomerular area; P<0.01), which was partially reversed by Ac-SDKP (23 +/- 4.0% of glomerular area; P=0.065, DOCA-salt vs. DOCA-salt+Ac-SDKP). Conclusion We concluded that Ac-SDKP prevents hypertension-induced inflammatory cell infiltration, collagen deposition, nephrin downregulation and albuminuria, which could lead to renoprotection in hypertensive mice. J Hypertens 29:330-338 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.