Vasoactive factors, Nox isoforms and redox biology in pulmonary arterial hypertension

Hood, Katie Yates (2016) Vasoactive factors, Nox isoforms and redox biology in pulmonary arterial hypertension. PhD thesis, University of Glasgow.

Abstract

Pulmonary arterial hypertension (PAH) is characterised by elevated pulmonary arterial pressures and obstructive lesions in the distal vasculature. As a result, the right ventricle is placed under excessive strain resulting in adaptive hypertrophy, progressing to maladaptive hypertrophy and failure. Women develop PAH more frequently than men. It is postulated that 17β-estradiol (E2) plays a role in disease pathogenesis and/or the E2 metabolic axis may be dysregulated in PAH. Growing evidence also implicates a role for ROS and oxidative stress in PAH, yet mechanisms linking these systems are elusive. We hypothesised that either E2 or the E2 metabolite, 16α-hydroxyestrone (16αOHE1), stimulates Nox-induced ROS generation and proliferative responses in human pulmonary artery smooth muscle cells (hPASMC) and that, in PAH, aberrant growth signaling promotes vascular remodeling. The pathophysiological significance of E2-Nox-dependent processes was studied in female Nox1-/- and Nox4-/- mice exposed to chronic hypoxia. HPASMCs from female non-PAH individuals (control hPASMC) and female PAH patients (PAH-hPASMC) were exposed to E2 and 16αOHE1 in the presence/absence of inhibitors of Nox1, Nox2 and Nox4, cytochrome P450 1B1 (CYP1B1) and estrogen receptors (ER), ERα, ERβ and G-protein coupled estrogen receptor (GPER). E2, through ERβ, increased Nox1 and Nox4-derived O2- and redox-sensitive growth in control hPASMCs. 16αOHE1, through ERα activation, stimulated O2- production in control hPASMCs and PAH-hPASMCs. E2- -stimulated O2- production was inhibited by CYP1B1 blockade. Basal expression of Nox1 and Nox4 was potentiated in PAH-hPASMCs. In control hPASMCs, 16αOHE1 increased p47phox and poldip2 and Nox1 expression. In PAH-hPASMCs, 16αOHE1 decreased nuclear factor erythroid-2-related factor-2 (Nrf-2) activity and expression of Nrf-2-regulated antioxidant genes in PAH-hPASMCs. Female Nox1-/-, but not Nox4-/- mice were protected against chronic hypoxia-induced pulmonary hypertension and vascular remodeling. Expression of CYP1B1 was increased in pulmonary arteries of wild-type and Nox4-/- mice exposed to hypoxia, yet this induction in CYP1B1 expression was absent in those arteries from hypoxic Nox1-/- mice. Findings detailed in Chapter 3 show that in PAH-hPASMCs, 16αOHE1 stimulates redox-sensitive cell growth through both Nox1 and Nox4. In vivo studies exhibited protection against pulmonary hypertension specifically in Nox1-/- mice. This study provides new insights through Nox1/ROS and Nrf-2 whereby 16αOHE1 influences hPASMC function, which when upregulated may contribute to vascular injury in PAH.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: R Medicine > RM Therapeutics. Pharmacology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Supervisor's Name: MacLean, Professor Margaret R and Touyz, Professor Rhian M
• Date of Award: 2016
• Embargo Date: 27 February 2020
• Depositing User: Katie Y Hood
• Unique ID: glathesis:2016-7973
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 28 Feb 2017 10:35
• Last Modified: 09 May 2017 15:43
• URI: https://theses.gla.ac.uk/id/eprint/7973