Loss of endothelial cell-specific autophagy-related protein 7 exacerbates doxorubicin-induced cardiotoxicity.

Doxorubicin (DOX) is an effective, broad-spectrum antineoplastic agent with serious cardiotoxic side effects, which may lead to the development of heart failure. Current strategies to diagnose, prevent, and treat DOX-induced cardiotoxicity (DIC) are inadequate. Recent evidence has linked the dysregulation and destruction of the vascular endothelium to the development of DIC. Autophagy is a conserved pro-survival mechanism that recycles and removes damaged sub-cellular components. Autophagy-related protein 7 (ATG7) catalyzes autophagosome formation, a critical step in autophagy. In this study, we used endothelial cell-specific Atg7 knockout (EC-Atg7 -/- ) mice to characterize the role of endothelial cell-specific autophagy in DIC. DOX-treated EC-Atg7 -/- mice showed reduced survival and a greater decline in cardiac function compared to wild-type controls. Histological assessments revealed increased cardiac fibrosis in DOX-treated EC-Atg7 -/- mice. Furthermore, DOX-treated EC-Atg7 -/- mice had elevated serum levels of creatine kinase-myocardial band, a biomarker for cardiac damage. Thus, the lack of EC-specific autophagy exacerbated DIC. Future studies on the relationship between EC-specific autophagy and DIC could establish the importance of endothelium protection in preventing DIC.

Disruption of endothelial cell intraflagellar transport protein 88 exacerbates doxorubicin-induced cardiotoxicity.

AIMS: Doxorubicin (DOX) is a potent anticancer drug with severe dose-dependent cardiotoxicity. To address this issue, previous research primarily focused on DOX-induced toxicity on cardiomyocytes. However, more recent research has looked into the endothelium as a therapeutic target due to the emerging role of endothelial cells in the support of cardiomyocyte survival and function. MAIN METHODS: We investigated a novel role of endothelial cell (EC) primary cilia in the prevention of DOX-mediated cardiotoxicity. Mice lacking EC primary cilia, via the deletion of EC-specific intraflagellar protein 88 (IFT88) expression, were administered DOX (20 mg/kg i.p.), and assessed for survival, cardiac function, cardiac structure changes, and indices of cardiomyocyte injury. KEY FINDINGS: DOX-treatment resulted in reduced survival and cardiac function (ejection fraction and fractional shortening) in EC-IFT88-/- mice vs. their similarly treated wild-type littermates. Cardiomyocyte vacuolization, cardiac fibrosis, and serum CK-MB levels were also increased in DOX-treated mice compared to saline-treated controls. However, these parameters were not significantly different when comparing WT and EC-IFT88-/- mice after DOX treatment. SIGNIFICANCE: The loss of EC primary cilia accelerated DOX-mediated mortality and reduced cardiac function, suggesting pathways downstream of ciliary-mediated signal transduction as potential targets to promote EC support of cardiomyocyte function during DOX treatment.

The SGLT2 inhibitor empagliflozin reduces mortality and prevents progression in experimental pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a rare, but progressive and devastating vascular disease with few treatment options to prevent the advancement to right ventricular dysfunction hypertrophy and failure. Empagliflozin, a sodium-glucose cotransporter 2 (SGLT2) inhibitor, enhances urinary glucose excretion as well as reduces cardiovascular events and mortality in individuals with type 2 diabetes. While empagliflozin has been reported to lower systemic hypertension due to increased diuresis, the effect of empagliflozin on PAH is unknown. We used monocrotaline (MCT)-treated Sprague-Dawley rats to determine if empagliflozin alters PAH-associated outcomes. Compared to vehicle control, daily empagliflozin administration significantly improved survival in rats with severe MCT-induced PAH. Hemodynamic assessments showed that empagliflozin treatment significantly reduced mean pulmonary artery pressure, right ventricular systolic pressure, and increased pulmonary acceleration time. Empagliflozin treatment resulted in reduced right ventricular hypertrophy and fibrosis. Histological and molecular assessments of lung vasculature revealed significantly reduced medial wall thickening and decreased muscularization of pulmonary arterioles after empagliflozin treatment compared to vehicle-treated rats. In summary, SGLT2 inhibition with empagliflozin lowered mortality, reduced right ventricle systolic pressure, and attenuated maladaptive pulmonary remodeling in MCT-induced PAH. Clinical studies evaluating the efficacy of SGLT-2 inhibition should be considered for patients with PAH.

Role of endothelial primary cilia as fluid mechanosensors on vascular health.

Primary cilia are microtubule-based organelles that protrude from the cell surface of many mammalian cell types, including endothelial and epithelial cells, osteoblasts, and neurons. These antennal-like projections enable cells to detect extracellular stimuli and elicit responses via intracellular signaling mechanisms. Primary cilia on endothelial cells lining blood vessels function as calcium-dependent mechanosensors that sense blood flow. In doing so, they facilitate the regulation of hemodynamic parameters within the vascular system. Defects in endothelial primary cilia result in inappropriate blood flow-induced responses and contribute to the development of vascular dysfunctions, including atherosclerosis, hypertension, and aneurysms. This review examines the current understanding of vascular endothelial cilia structure and function and their role in the vascular system. Future directions for primary cilia research and treatments for ciliary-based pathologies are discussed.