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Angiotensin-converting enzyme inhibitors (ACEi) are part of the indicated treatment in hypertensive African Americans. ACEi have blood pressure-independent effects that may make them preferred for certain patients. We aimed to evaluate the impact of ACEi on anti-fibrotic biomarkers in African American hypertensive patients with left ventricular hypertrophy (LVH). We conducted a post hoc analysis of a randomized controlled trial in which hypertensive African American patients with LVH and vitamin D deficiency were randomized to receive intensive antihypertensive therapy plus vitamin D supplementation or placebo. We selected patients who had detectable lisinopril (lisinopril group) in plasma using liquid-chromatography/mass spectrometry analysis and compared them to subjects who did not (comparison group) at the one-year follow-up. The pro-fibrotic marker type 1 procollagen C-terminal propeptide (PICP) and the anti-fibrotic markers matrix metalloproteinase-1 (MMP-1), tissue inhibitor of metalloproteinases 1 (TIMP-1), telopeptide of collagen type I (CITP), and N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) peptide were measured. Sixty-six patients were included, and the mean age was 46.2 ± 8 years. No difference was observed in the number and intensity of antihypertensive medications prescribed in each group. Patients with detectable lisinopril had lower blood pressure than those in the comparison group. The anti-fibrotic markers Ac-SDKP, MMP-1, and MMP-1/TIMP-1 ratio were higher in patients with detectable ACEi (all p < .05). In a model adjusted for systolic blood pressure, MMP-1/TIMP-1 (p = .02) and Ac-SDKP (p < .001) levels were associated with lisinopril. We conclude that ACEi increase anti-fibrotic biomarkers in hypertensive African Americans with LVH, suggesting that they may offer added benefit over other agents in such patients. [ABSTRACT FROM AUTHOR]

The antifibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is released from thymosin-β4 (Tβ4) by the meprin-α and prolyl oligopeptidase (POP) enzymes and is hydrolyzed by angiotensin-converting enzyme (ACE). Ac-SDKP is present in urine; however, it is not clear whether de novo tubular release occurs or if glomerular filtration is the main source. We hypothesized that Ac-SDKP is released into the lumen of the nephrons and that it exerts an antifibrotic effect. We determined the presence of Tβ4, meprin-α, and POP in the kidneys of Sprague-Dawley rats. The stop-flow technique was used to evaluate Ac-SDKP formation in different nephron segments. Finally, we decreased Ac-SDKP formation by inhibiting the POP enzyme and evaluated the long-term effect in renal fibrosis. The Tβ4 precursor and the releasing enzymes meprin-α and POP were expressed in the kidneys. POP enzyme activity was almost double that in the renal medulla compared with the renal cortex. With the use of the stop-flow technique, we detected the highest Ac-SDKP concentrations in the distal nephron. The infusion of a POP inhibitor into the kidney decreased the amount of Ac-SDKP in distal nephron segments and in the proximal nephron to a minor extent. An ACE inhibitor increased the Ac-SDKP content in all nephron segments, but the increase was highest in the distal portion. The chronic infusion of a POP inhibitor increased kidney medullary fibrosis, which was prevented by Ac-SDKP. We conclude that Ac-SDKP is released by the nephron and is part of an important antifibrotic system in the kidney. [ABSTRACT FROM AUTHOR]

Systemic lupus erythematosus (SLE) is an autoimmune disease with a high prevalence of hypertension. NZBWF1 (SLE-Hyp) mice develop hypertension that can be prevented by modulating T cells. The peptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) decreases renal damage and improves renal function in a model of SLE without hypertension (MRL/lpr). However, it is not known whether Ac-SDKP prevents hypertension in NZBWF1 mice. We hypothesized that in SLE-Hyp, Ac-SDKP prevents hypertension and renal damage by modulating T cells. Animals were divided into four groups: (1) control + vehicle, (2) control + Ac-SDKP, (3) SLE + vehicle, and (4) SLE + Ac-SDKP. Systolic blood pressure (SBP), albuminuria, renal fibrosis, and T-cell phenotype were analyzed. SBP was higher in SLE compared to control mice and was not decreased by Ac-SDKP treatment. Half of SLE mice developed an acute and severe form of hypertension accompanied by albuminuria followed by death. Ac-SDKP delayed development of severe hypertension, albuminuria, and early mortality, but this delay did not reach statistical significance. Ac-SDKP prevented glomerulosclerosis, but not interstitial fibrosis in SLE-Hyp mice. SLE-Hyp mice showed a decrease in helper and cytotoxic T cells as well as an increase in double negative lymphocytes and T helper 17 cells, but these cells were unaffected by Ac-SDKP. In conclusion, Ac-SDKP prevents kidney damage, without affecting blood pressure in an SLE animal model. However, during the acute relapse of SLE, Ac-SDKP might also delay the manifestation of an acute and severe form of hypertension leading to early mortality. Ac-SDKP is a potential tool to treat renal damage in SLEHyp mice. [ABSTRACT FROM AUTHOR]