Glucose consumption of vascular cell types in culture: toward optimization of experimental conditions

Mitochondrial CypD Acetylation Promotes Endothelial Dysfunction and Hypertension

BACKGROUND

Nearly half of adults have hypertension, a major risk factor for cardiovascular disease. Mitochondrial hyperacetylation is linked to hypertension, but the role of acetylation of specific proteins is not clear. We hypothesized that acetylation of mitochondrial CypD (cyclophilin D) at K166 contributes to endothelial dysfunction and hypertension.

METHODS

To test this hypothesis, we studied CypD acetylation in patients with essential hypertension, defined a pathogenic role of CypD acetylation in deacetylation mimetic CypD-K166R mutant mice and endothelial-specific GCN5L1 (general control of amino acid synthesis 5 like 1)-deficient mice using an Ang II (angiotensin II) model of hypertension.

RESULTS

Arterioles from hypertensive patients had 280% higher CypD acetylation coupled with reduced Sirt3 (sirtuin 3) and increased GCN5L1 levels. GCN5L1 regulates mitochondrial protein acetylation and promotes CypD acetylation, which is counteracted by mitochondrial deacetylase Sirt3. In human aortic endothelial cells, GCN5L1 depletion prevents superoxide overproduction. Deacetylation mimetic CypD-K166R mice were protected from vascular oxidative stress, endothelial dysfunction, and Ang II-induced hypertension. Ang II-induced hypertension increased mitochondrial GCN5L1 and reduced Sirt3 levels resulting in a 250% increase in GCN5L1/Sirt3 ratio promoting CypD acetylation. Treatment with mitochondria-targeted scavenger of cytotoxic isolevuglandins (mito2HOBA) normalized GCN5L1/Sirt3 ratio, reduced CypD acetylation, and attenuated hypertension. The role of mitochondrial acetyltransferase GCN5L1 in the endothelial function was tested in endothelial-specific GCN5L1 knockout mice. Depletion of endothelial GCN5L1 prevented Ang II-induced mitochondrial oxidative stress, reduced the maladaptive switch of vascular metabolism to glycolysis, prevented inactivation of endothelial nitric oxide, preserved endothelial-dependent relaxation, and attenuated hypertension.

CONCLUSIONS

These data support the pathogenic role of CypD acetylation in endothelial dysfunction and hypertension. We suggest that targeting cytotoxic mitochondrial isolevuglandins and GCN5L1 reduces CypD acetylation, which may be beneficial in cardiovascular disease.

Mitochondrial fission inhibition protects against hypertension induced by angiotensin II

Mitochondrial dysfunction has been implicated in various types of cardiovascular disease including hypertension. Mitochondrial fission fusion balance is critical to mitochondrial quality control, whereas enhanced fission has been reported in several models of cardiovascular disease. However, limited information is available regarding the contribution of mitochondrial fission in hypertension. Here, we have tested the hypothesis that inhibition of mitochondrial fission attenuates the development of hypertension and associated vascular remodeling. In C57BL6 mice infused with angiotensin II for 2 weeks, co-treatment of mitochondrial fission inhibitor, mdivi1, significantly inhibited angiotensin II-induced development of hypertension assessed by radiotelemetry. Histological assessment of hearts and aortas showed that mdivi1 inhibited vessel fibrosis and hypertrophy induced by angiotensin II. This was associated with attenuation of angiotensin II-induced decline in mitochondrial aspect ratio seen in both the endothelial and medial layers of aortas. Mdivi1 also mitigated angiotensin II-induced cardiac hypertrophy assessed by heart weight-to-body weight ratio as well as by echocardiography. In ex vivo experiments, mdivi1 inhibited vasoconstriction and abolished the enhanced vascular reactivity by angiotensin II in small mesenteric arteries. Proteomic analysis on endothelial cell culture media with angiotensin II and/or mdivi1 treatment revealed that mdivi1 inhibited endothelial cell hypersecretory phenotype induced by angiotensin II. In addition, mdivi1 attenuated angiotensin II-induced protein induction of periostin, a myofibroblast marker in cultured vascular fibroblasts. In conclusion, these data suggest that mdivi1 prevented angiotensin II-induced hypertension and cardiovascular remodeling via multicellular mechanisms in the vasculature.

Infused juice concentrate of Japanese plum Prunus mume attenuates inflammatory vascular remodeling in a mouse model of hypertension induced by angiotensin II

Fruit from the Prunus mume tree is a traditional food in Japan. Recently, bainiku-ekisu, an infused juice concentrate of Japanese Prunus mume, is attracting attention as a health promoting supplement. Angiotensin II (Ang II) plays a central role in development of hypertension. It has been reported that bainiku-ekisu treatment attenuates the growth-promoting signaling induced by Ang II in vascular smooth muscle cells. However, whether bainiku-ekisu has any effect on an animal model of hypertension remains unknown. Therefore, this study was designed to explore the potential anti-hypertensive benefit of bainiku-ekisu utilizing a mouse model of hypertension with Ang II infusion. Male C57BL/6 mice were infused with Ang II for 2 weeks and given 0.1% bainiku-ekisu containing water or normal water for 2 weeks with blood pressure evaluation. After 2 weeks, mice were euthanized, and the aortas were collected for evaluation of remodeling. Aortic medial hypertrophy was observed in control mice after Ang II infusion, which was attenuated in bainiku-ekisu group with Ang II infusion. Bainiku-ekisu further attenuated aortic induction of collagen producing cells and immune cell infiltration. Development of hypertension induced by Ang II was also prevented by bainiku-ekisu. Echocardiograph indicated protection of Ang II-induced cardiac hypertrophy by bainiku-ekisu. In vascular fibroblasts, bainiku-ekisu attenuated vascular cell adhesion molecule-1 induction, an endoplasmic reticulum stress marker, inositol requiring enzyme-1α phosphorylation, and enhancement in glucose consumption in response to Ang II. In conclusion, Bainiku-ekisu prevented Ang II-induced hypertension and inflammatory vascular remodeling. Potential cardiovascular health benefit to taking bainiku-ekisu should be further studied.

Endoplasmic Reticulum Chemical Chaperone 3-Hydroxy-2-Naphthoic Acid Reduces Angiotensin II-Induced Vascular Remodeling and Hypertension In Vivo and Protein Synthesis In Vitro

Background Investigations into alternative treatments for hypertension are necessary because current treatments cannot fully reduce the risk for the development of cardiovascular diseases. Chronic activation of unfolded protein response attributable to the endoplasmic reticulum stress has been proposed as a potential therapeutic target for hypertension and associated vascular remodeling. Triggered by the accumulation of misfolded proteins, chronic unfolded protein response leads to downstream signaling of cellular inflammation and dysfunction. Here, we have tested our hypothesis that a novel chemical chaperone, 3-hydroxy-2-naphthoic acid (3HNA) can attenuate angiotensin II (AngII)-induced vascular remodeling and hypertension. Methods and Results Mice were infused with AngII for 2 weeks to induce vascular remodeling and hypertension with or without 3HNA treatment. We found that injections of 3HNA prevented hypertension and increase in heart weight body weight ratio induced by AngII infusion. Histological assessment revealed that 3HNA treatment prevented vascular medial thickening as well as perivascular fibrosis in response to AngII infusion. In cultured vascular smooth muscle cells, 3HNA attenuated enhancement in protein synthesis induced by AngII. In vascular adventitial fibroblasts, 3HNA prevented induction of unfolded protein response markers. Conclusions We present evidence that a chemical chaperone 3HNA prevents vascular remodeling and hypertension in mice with AngII infusion, and 3HNA further prevents increase in protein synthesis in AngII-stimulated vascular smooth muscle cells. Using 3HNA may represent a novel therapy for hypertension with multiple benefits by preserving protein homeostasis under cardiovascular stress.

Tri-Layered Vascular Grafts Guide Vascular Cells’ Native-like Arrangement

Bionic grafts hold great promise for directing tissue regeneration. In vascular tissue engineering, although a large number of synthetic grafts have been constructed, these substitutes only partially recapitulated the tri-layered structure of native arteries. Synthetic polymers such as poly(l-lactide-co-ε-caprolactone) (PLCL) possess good biocompatibility, controllable degradation, remarkable processability, and sufficient mechanical strength. These properties of PLCL show great promise for fabricating synthetic vascular substitutes. Here, tri-layered PLCL vascular grafts (TVGs) composed of a smooth inner layer, circumferentially aligned fibrous middle layer, and randomly distributed fibrous outer layer were prepared by sequentially using ink printing, wet spinning, and electrospinning techniques. TVGs possessed kink resistance and sufficient mechanical properties (tensile strength, elastic modulus, suture retention strength, and burst pressure) equivalent to the gold standard conduits of clinical application, i.e., human saphenous veins and human internal mammary arteries. The stratified structure of TVGs exhibited a visible guiding effect on specific vascular cells including enhancing endothelial cell (EC) monolayer formation, favoring vascular smooth muscle cells’ (VSMCs) arrangement and elongation, and facilitating fibroblasts’ proliferation and junction establishment. Our research provides a new avenue for designing synthetic vascular grafts with polymers.