Interferon stimulated gene 15 pathway is a novel mediator of endothelial dysfunction and aneurysms development in angiotensin II infused mice through increased oxidative stress.

Aims Interferon-stimulated gene 15 (ISG15) encodes an ubiquitin-like protein that induces a reversible post-translational modification (ISGylation) and can also be secreted as a free form. ISG15 plays an essential role as host-defense response to microbial infection; however, its contribution to vascular damage associated to hypertension is unknown. Methods and results Bioinformatics identified ISG15 as a mediator of hypertension-associated vascular damage. ISG15 expression positively correlated with systolic and diastolic blood pressure and carotid intima-media thickness in human peripheral blood mononuclear cells. Consistently, Isg15 expression was enhanced in aorta from hypertension models and in angiotensinII (AngII)-treated vascular cells and macrophages. Proteomics revealed differential expression of proteins implicated in cardiovascular function, extracellular matrix and remodeling, and vascular redox state in aorta from AngII-infused ISG15-/- mice. Moreover, ISG15-/- mice were protected against AngII-induced hypertension, vascular stiffness, elastin remodeling, endothelial dysfunction, and expression of inflammatory and oxidative stress markers. Conversely, mice with excessive ISGylation (USP18C61A) show enhanced AngII-induced hypertension, vascular fibrosis, inflammation and reactive oxygen species (ROS) generation along with elastin breaks, aortic dilation and rupture. Accordingly, human and murine abdominal aortic aneurysms showed augmented ISG15 expression. Mechanistically, ISG15 induces vascular ROS production, while antioxidant treatment prevented ISG15-induced endothelial dysfunction and vascular remodeling. Conclusion ISG15 is a novel mediator of vascular damage in hypertension through oxidative stress and inflammation. Translational perspective Recent evidence from randomized clinical trials demonstrate the effectiveness of specific anti-inflammatory treatments in cardiovascular prevention. In this study we have identified a new inflammatory mediator involved in vascular damage in experimental and human hypertension and aneurysms. We found that interferon stimulated gene 15 (ISG15) is increased at the vascular level in animal models of hypertension and aneurysms. More importantly, ISG15 correlates with human hypertension, vascular remodeling, and aneurysms presence. Underlying mechanisms responsible for vascular damage induced by ISG15 include oxidative and inflammation. Our results further support the role of inflammation in vascular damage in different cardiovascular pathologies.