Potential role of NADPH oxidase 5 (NOX 5) in arterial hypertensiondevelopment of a new animal model and a recombinant adenovirus

Resumen

Oxidative stress, created by an imbalance between reactive oxygen species (ROS) production and antioxidant capacity, is a critical mechanism that underlies the pathophysiology of cardiovascular diseases, including arterial hypertension. Superoxide anion is a second messenger in redox signalling and necessary for antimicrobial defence, however in pathological situations can induce tissue damage by the oxidation of macromolecules, the depletion of nitric oxide bioavailability and peroxynitrites production. The NADPH oxidase (Nox) enzyme family is the main source of superoxide anion in the vascular wall and its enhanced expression and ROS production have been shown to play a critical role in the onset and/or development of hypertension. Nox 5 expression has been found to be increased in several cardiovascular pathologies, including hypertension. However, there are many aspects of Nox 5 function and relevance in the vascular pathophysiology that still remain unknown. This lack of knowledge can be explained because Nox 5 was the last homolog of NADPH oxidase family to be discovered and specially due to the loss of Nox 5 gene in rodents during evolution. In the present study we developed two experimental tools to gain further knowledge in Nox 5 role in redox signal transduction in endothelial cells and its contribution to hypertension initiation and/or progression: a recombinant Nox 5β adenovirus and a transgenic mice model that overexpress Nox 5β in endothelial cells. Nox 5β overexpression after adenoviral infection in human aortic endothelial cells resulted in a significant enhancement of extracellular superoxide and hydrogen peroxide production and led to a significant increase in cellular apoptosis by caspases 3 and 7. Nox 5β overexpression significantly reduced Nox 4 and NOS3 mRNA expression; and significantly increased COX2, SOD1 and SOD2 mRNA expression. Infection of human aortic endothelial cells with Nox 5β adenovirus activated the UPR pathway, increasing Ire1α and CHOP mRNA expression, GRP78 protein expression and reducing calnexin protein expression. The transgenic mouse model generated in this project specifically overexpressed Nox 5β in endothelial cells after induction with tamoxifen, but Nox 5β expression in the endothelium did not affect systolic, diastolic, mean blood pressure, heart rate or mouse weight in an ageing mouse model or in a hypertensive angiotensin II-infused mouse model.