Pharmacological restoration of autophagy reduces hypertension-related stroke occurrence

Autophagy. 2020 Aug;16(8):1468-1481. doi: 10.1080/15548627.2019.1687215. Epub 2019 Nov 12.

Abstract

The identification of the mechanisms predisposing to stroke may improve its preventive and therapeutic strategies in patients with essential hypertension. The role of macroautophagy/autophagy in the development of hypertension-related stroke needs to be clarified. We hypothesized that a defective autophagy may favor hypertension-related spontaneous stroke by promoting mitochondrial dysfunction. We studied autophagy in the stroke-prone spontaneously hypertensive (SHRSP) rat, which represents a clinically relevant model of stroke associated with high blood pressure. We assessed autophagy, mitophagy and NAD+:NADH levels in brains of SHRSP and stroke-resistant SHR fed with high salt diet. Vascular smooth muscle cells silenced for the mitochondrial complex I subunit Ndufc2 gene (NADH:ubiquinone oxidoreductase subunit C2) and cerebral endothelial cells isolated from SHRSP were also used to assess autophagy/mitophagy and mitochondrial function in response to high salt levels. We found a reduction of autophagy in brains of high salt-fed SHRSP. Autophagy impairment was associated with NDUFC2 downregulation, mitochondrial dysfunction and NAD+ depletion. Restoration of NAD+ levels by nicotinamide administration reactivated autophagy and reduced stroke development in SHRSP. A selective reactivation of autophagy/mitophagy by Tat-Beclin 1 also reduced stroke occurrence, restored autophagy/mitophagy and improved mitochondrial function. Endothelial progenitor cells (EPCs) from subjects homozygous for the thymine allele variant at NDUFC2/rs11237379, which is associated with NDUFC2 deficiency and increased stroke risk, displayed an impairment of autophagy and increased senescence in response to high salt levels. EPC senescence was rescued by Tat-Beclin 1. Pharmacological activation of autophagy may represent a novel therapeutic strategy to reduce stroke occurrence in hypertension.

Abbreviations: 10 VSMCs: aortic vascular smooth muscle cells; COX4I1/COX IV: cytochrome c oxidase subunit 4I1; ECs: endothelial cells; EPCs: endothelial progenitor cells; JD: Japanese-style diet; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NAD: nicotinamide adenine dinucleotide; NDUFC2: NADH:ubiquinone oxidoreductase subunit C2; NMN: nicotinamide mononucleotide; RD: regular diet; SHRSP: stroke-prone spontaneously hypertensive rat; SHRSR: stroke-resistant spontaneously hypertensive rat.

Keywords: Animal model; NDUFC2; autophagy; human EPCs; mitochondria; stroke.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy*
  • Beclin-1 / metabolism
  • Brain / pathology
  • Cell Survival
  • Down-Regulation
  • Endothelial Progenitor Cells / metabolism
  • Hypertension / complications*
  • Male
  • Mitochondria / metabolism
  • Mitochondria / ultrastructure
  • Mitophagy
  • NAD / metabolism
  • Nicotinamide Mononucleotide / metabolism
  • Rats, Inbred SHR
  • Stroke / etiology*

Substances

  • Beclin-1
  • NAD
  • Nicotinamide Mononucleotide

Grant support

This work was supported by grants from the Italian Ministry of Health and the “5 per mille” grant to SR and MV, and by a grant from the Italian Ministry of Health to SS [GR-2013-02355401].