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Aim: Protein disulfide isomerases (PDIs) are involved in platelet aggregation and intravascular thrombosis, but their role in regulating endothelial function is unclear. Here, we characterized the involvement of vascular PDIA1 in angiotensin II (Ang II)‐induced endothelial dysfunction in mice. Methods: Endothelial dysfunction was induced in C57BL/6JCmd male mice via Ang II subcutaneous infusion, and PDIA1 was inhibited with bepristat. Endothelial function was assessed in vivo with magnetic resonance imaging and ex vivo with a myography, while arterial stiffness was measured as pulse wave velocity. Nitric oxide (NO) bioavailability was measured in the aorta (spin‐trapping electron paramagnetic resonance) and plasma (NO2− and NO3− levels). Oxidative stress, eNOS uncoupling (DHE‐based aorta staining), and thrombin activity (thrombin–antithrombin complex; calibrated automated thrombography) were evaluated. Results: The inhibition of PDIA1 by bepristat in Ang II‐treated mice prevented the impairment of NO‐dependent vasodilation in the aorta as evidenced by the response to acetylcholine in vivo, increased systemic NO bioavailability and the aortic NO production, and decreased vascular stiffness. Bepristat's effect on NO‐dependent function was recapitulated ex vivo in Ang II‐induced endothelial dysfunction in isolated aorta. Furthermore, bepristat diminished the Ang II‐induced eNOS uncoupling and overproduction of ROS without affecting thrombin activity. Conclusion: In Ang II‐treated mice, the inhibition of PDIA1 normalized the NO‐ROS balance, prevented endothelial eNOS uncoupling, and, thereby, improved vascular function. These results indicate the importance of vascular PDIA1 in regulating endothelial function, but further studies are needed to elucidate the details of the mechanisms involved. [ABSTRACT FROM AUTHOR]

Aims Endothelial dysfunction (ED) and red blood cell distribution width (RDW) are both prognostic factors in heart failure (HF), but the relationship between them is not clear. In this study, we used a unique mouse model of chronic HF driven by cardiomyocyte-specific overexpression of activated Gαq protein (Tgαq*44 mice) to characterize the relationship between the development of peripheral ED and the occurrence of structural nanomechanical and biochemical changes in red blood cells (RBCs). Methods and results Systemic ED was detected in vivo in 8-month-old Tgαq*44 mice, as evidenced by impaired acetylcholine-induced vasodilation in the aorta and increased endothelial permeability in the brachiocephalic artery. ED in the aorta was associated with impaired nitric oxide (NO) production in the aorta and diminished systemic NO bioavailability. ED in the aorta was also characterized by increased superoxide and eicosanoid production. In 4- to 6-month-old Tgαq*44 mice, RBC size and membrane composition displayed alterations that did not result in significant changes in their nanomechanical and functional properties. However, 8-month-old Tgαq*44 mice presented greatly accentuated structural and size changes and increased RBC stiffness. In 12-month-old Tgαq*44 mice, the erythropathy was featured by severely altered RBC shape and elasticity, increased RDW, impaired RBC deformability, and increased oxidative stress (gluthatione (GSH)/glutathione disulfide (GSSG) ratio). Moreover, RBCs taken from 12-month-old Tgαq*44 mice, but not from 12-month-old FVB mice, coincubated with aortic rings from FVB mice, induced impaired endothelium-dependent vasodilation and this effect was partially reversed by an arginase inhibitor [2(S)-amino-6-boronohexanoic acid]. Conclusion In the Tgαq*44 murine model of HF, systemic ED accelerates erythropathy and, conversely, erythropathy may contribute to ED. These results suggest that erythropathy may be regarded as a marker and a mediator of systemic ED in HF. RBC arginase and possibly other RBC-mediated mechanisms may represent novel therapeutic targets for systemic ED in HF. [ABSTRACT FROM AUTHOR]

Abstract Endothelial dysfunction is recognized as a critical condition in the development of cardiovascular disorders. This multifactorial process involves changes in the biochemical and mechanical properties of endothelial cells leading to disturbed release of vasoprotective mediators. Hypercholesterolemia and increased stiffness of the endothelial cortex are independently shown to result in reduced release of nitric oxide and thus endothelial dysfunction. However, direct evidence linking these parameters to each other is missing. Here, a novel method combining Raman spectroscopy for biochemical analysis and Atomic Force Microscopy (AFM) for analyzing the endothelial nanomechanics was established. Using this dual approach, the same areas of native ex vivo aortas were investigated, either derived from mice with endothelial dysfunction (ApoE/LDLR−/−) or wild type mice. In particular an increased intracellular lipid content and elevated cortical stiffness/elasticity were shown in ApoE/LDLR−/− aortas, demonstrating a direct link between endothelial dysfunction, the biochemical composition and the nanomechanical properties of endothelial cells. Graphical Abstract In the present work, a combined method of Raman spectroscopy and Atomic Force Microscopy (AFM) was established to analyze the biochemical and nanomechanical properties of endothelial cells ex vivo. By that, increased amounts of intracellular lipids and elevated cortical stiffness values were detected in a mouse model for endothelial dysfunction (ApoE/LDLR−/− mice). Both parameters decrease endothelial nitric oxide production and can thus be regarded as independent markers for endothelial dysfunction. Hence, applying our novel method, we demonstrate an interdependency between intracellular lipid contents and cortical nanomechanics contributing to the development of endothelial dysfunction and cardiovascular diseases. Unlabelled Image [ABSTRACT FROM AUTHOR]