Arterial remodeling: the role of mitochondrial metabolism in vascular smooth muscle cells

Platelet bioenergetic profiling uncovers a metabolic pattern of high dependency on mitochondrial fatty acid oxidation in type 2 diabetic patients who developed in-stent restenosis

Although platelet bioenergetic dysfunction is evident early in the pathogenesis of diabetic macrovascular complications, the bioenergetic characteristics in type 2 diabetic patients who developed coronary in-stent restenosis (ISR) and their effects on platelet function remain unclear. Here, we performed platelet bioenergetic profiling to characterize the bioenergetic alterations in 28 type 2 diabetic patients with ISR compared with 28 type 2 diabetic patients without ISR (non-ISR) and 28 healthy individuals. Generally, platelets from type 2 diabetic patients with ISR exhibited a specific bioenergetic alteration characterized by high dependency on fatty acid (FA) oxidation, which subsequently induced complex III deficiency, causing decreased mitochondrial respiration, increased mitochondrial oxidant production, and low efficiency of mitochondrial ATP generation. This pattern of bioenergetic dysfunction showed close relationships with both α-granule and dense granule secretion as measured by surface P-selectin expression, ATP release, and profiles of granule cargo proteins in platelet releasates. Importantly, ex vivo reproduction of high dependency on FA oxidation by exposing non-ISR platelets to its agonist mimicked the bioenergetic dysfunction observed in ISR platelets and enhanced platelet secretion, whereas pharmaceutical inhibition of FA oxidation normalized the respiratory and redox states of ISR platelets and diminished platelet secretion. Further, causal mediation analyses identified a strong association between high dependency on FA oxidation and increased angiographical severity of ISR, which was significantly mediated by the status of platelet secretion. Our findings, for the first time, uncover a pattern of bioenergetic dysfunction in ISR and enhance current understanding of the mechanistic link of high dependency on FA oxidation to platelet abnormalities in the context of diabetes.

Association between metabolic dysfunction-associated fatty liver disease and abdominal aortic aneurysm

BACKGROUND AND AIMS

Abdominal aortic aneurysm (AAA) is the second most common aortic pathological manifestation. Metabolic dysfunction-associated fatty liver disease (MAFLD) has a wide impact on the cardiovascular system and may be a risk factor for AAA. The aim of this study was to investigate whether MAFLD is associated with the risk of AAA.

METHODS AND RESULTS

We used data from the prospective UK Biobank cohort study. MAFLD is defined as hepatic steatosis plus metabolic abnormality, type 2 diabetes, or overweight/obesity. AAA is collected by ICD-10 code. Cox regression was established to analyze the association between MAFLD and AAA. A total of 370203 participants were included; the average age of the participants was 56.7 ± 8.0 years, and 134649 (36.4 %) were diagnosed with MAFLD. During the 12.5 years of follow-up, 1561 (0.4 %) participants developed AAA. After fully adjusting for confounding factors, individuals with MAFLD had a significantly increased risk of AAA (HR 1.521, 95 % CI 1.351-1.712, p < 0.001). Importantly, the risk of AAA increases with the severity of MAFLD as assessed by fibrosis scores. These associations were consistent according to sex, weight, and alcohol consumption but weaker in elderly or diabetics (P for interaction <0.05). The association between the MAFLD phenotype and AAA was independent of the polygenic risk score. Additionally, MAFLD was not associated with thoracic aortic aneurysm or aortic dissection events.

CONCLUSIONS

There was a significant relationship between MAFLD and AAA. These findings strongly recommend early prevention of AAA by intervening in MAFLD.

Transketolase drives the development of aortic dissection by impairing mitochondrial bioenergetics

AIM

Aortic dissection (AD) is a disease with rapid onset but with no effective therapeutic drugs yet. Previous studies have suggested that glucose metabolism plays a critical role in the progression of AD. Transketolase (TKT) is an essential bridge between glycolysis and the pentose phosphate pathway. However, its role in the development of AD has not yet been elucidated. In this study, we aimed to explore the role of TKT in AD.

METHODS

We collected AD patients' aortic tissues and used high-throughput proteome sequencing to analyze the main factors influencing AD development. We generated an AD model using BAPN in combination with angiotensin II (Ang II) and pharmacological inhibitors to reduce TKT expression. The effects of TKT and its downstream mediators on AD were elucidated using human aortic vascular smooth muscle cells (HAVSMCs).

RESULTS

We found that glucose metabolism plays an important role in the development of AD and that TKT is upregulated in patients with AD. Western blot and immunohistochemistry confirmed that TKT expression was upregulated in mice with AD. Reduced TKT expression attenuated AD incidence and mortality, maintained the structural integrity of the aorta, aligned elastic fibers, and reduced collagen deposition. Mechanistically, TKT was positively associated with impaired mitochondrial bioenergetics by upregulating AKT/MDM2 expression, ultimately contributing to NDUFS1 downregulation.

CONCLUSION

Our results provide new insights into the role of TKT in mitochondrial bioenergetics and AD progression. These findings provide new intervention options for the treatment of AD.

Mitochondrial influences on smooth muscle phenotype

Smooth muscle cells transition reversibly between contractile and noncontractile phenotypes in response to diverse influences, including many from mitochondria. Numerous molecules including myocardin, procontractile miRNAs, and the mitochondrial protein prohibitin-2 promote contractile differentiation; this is opposed by mitochondrial reactive oxygen species (mtROS), high lactate concentrations, and metabolic reprogramming induced by mitophagy and/or mitochondrial fission. A major pathway through which vascular pathologies such as oncogenic transformation, pulmonary hypertension, and atherosclerosis cause loss of vascular contractility is by enhancing mitophagy and mitochondrial fission with secondary effects on smooth muscle phenotype. Proproliferative miRNAs and the mitochondrial translocase TOMM40 also attenuate contractile differentiation. Hypoxia can initiate loss of contractility by enhancing mtROS and lactate production while simultaneously depressing mitochondrial respiration. Mitochondria can reduce cytosolic calcium by moving it across the inner mitochondrial membrane via the mitochondrial calcium uniporter, and then through mitochondria-associated membranes to and from calcium stores in the sarcoplasmic/endoplasmic reticulum. Through these effects on calcium, mitochondria can influence multiple calcium-sensitive nuclear transcription factors and genes, some of which govern smooth muscle phenotype, and possibly also the production of genomically encoded mitochondrial proteins and miRNAs (mitoMirs) that target the mitochondria. In turn, mitochondria also can influence nuclear transcription and mRNA processing through mitochondrial retrograde signaling, which is currently a topic of intensive investigation. Mitochondria also can signal to adjacent cells by contributing to the content of exosomes. Considering these and other mechanisms, it is becoming increasingly clear that mitochondria contribute significantly to the regulation of smooth muscle phenotype and differentiation.

Wnt16 Promotes Vascular Smooth Muscle Contractile Phenotype and Function via Taz (Wwtr1) Activation in Male LDLR-/- Mice

Wnt16 is expressed in bone and arteries, and maintains bone mass in mice and humans, but its role in cardiovascular physiology is unknown. We show that Wnt16 protein accumulates in murine and human vascular smooth muscle (VSM). WNT16 genotypes that convey risk for bone frailty also convey risk for cardiovascular events in the Dallas Heart Study. Murine Wnt16 deficiency, which causes postnatal bone loss, also reduced systolic blood pressure. Electron microscopy demonstrated abnormal VSM mitochondrial morphology in Wnt16-null mice, with reductions in mitochondrial respiration. Following angiotensin-II (AngII) infusion, thoracic ascending aorta (TAA) dilatation was greater in Wnt16-/- vs Wnt16+/+ mice (LDLR-/- background). Acta2 (vascular smooth muscle alpha actin) deficiency has been shown to impair contractile phenotype and worsen TAA aneurysm with concomitant reductions in blood pressure. Wnt16 deficiency reduced expression of Acta2, SM22 (transgelin), and other contractile genes, and reduced VSM contraction induced by TGFβ. Acta2 and SM22 proteins were reduced in Wnt16-/- VSM as was Ankrd1, a prototypic contractile target of Yap1 and Taz activation via TEA domain (TEAD)-directed transcription. Wnt16-/- VSM exhibited reduced nuclear Taz and Yap1 protein accumulation. SiRNA targeting Wnt16 or Taz, but not Yap1, phenocopied Wnt16 deficiency, and Taz siRNA inhibited contractile gene upregulation by Wnt16. Wnt16 incubation stimulated mitochondrial respiration and contraction (reversed by verteporfin, a Yap/Taz inhibitor). SiRNA targeting Taz inhibitors Ccm2 and Lats1/2 mimicked Wnt16 treatment. Wnt16 stimulated Taz binding to Acta2 chromatin and H3K4me3 methylation. TEAD cognates in the Acta2 promoter conveyed transcriptional responses to Wnt16 and Taz. Wnt16 regulates cardiovascular physiology and VSM contractile phenotype, mediated via Taz signaling.

MiR-590-3p Promotes the Phenotypic Switching of Vascular Smooth Muscle Cells by Targeting Lysyl Oxidase

ABSTRACT

We investigated the clinical characteristics of patients with acute aortic dissection (AAD) and miR-590-3p levels in serum, tissue, and vascular smooth muscle cells. The effect of miR-590-3p on the vascular smooth muscle cell phenotype was assessed, and the regulation of lysyl oxidase by miR-5903p was determined. C57BL/6 mice were used to investigate the incidence of AAD and effects of miR-5903p on AAD. The miR-590-3p levels were measured in the aortae of mice, and hematoxylin and eosin staining and Masson staining were performed to identify the morphological features of the aorta. Comparative analysis revealed significant differences in clinical characteristics between patients with AAD and healthy control subjects, with most patients with AAD exhibiting concomitant hypertension and nearly 50% having atherosclerosis. Lysyl oxidase was a direct target of miR-590-3p. Lysyl oxidase overexpression inhibited switching of the vascular smooth muscle cell phenotype from contractile to synthetic, but miR-590-3p overexpression significantly reversed this change. In the mouse model, miR-590-3p upregulation increased the incidence of AAD to 93.3%, and its incidence decreased to 13.3% after miR-590-3p inhibition. Hematoxylin and eosin and Masson staining revealed that the miR-590-3p agomiR group had a greater loss of the contractile phenotype in the dissected aortic wall and an increased number of muscle fibers in the aortic wall, which contributed to thickening of the aortic wall and the formation of a false lumen in aortic dissection. miR-590-3p might be pivotal in the pathogenesis of AAD. Thus, targeting miR-590-3p or its downstream pathways could represent a therapeutic approach for AAD.

Adjusted vascular contractility relies on integrity of progranulin pathway: Insights into mitochondrial function

Objective

Cardiovascular disease (CVD) is a global health crisis and a leading cause of mortality. The intricate interplay between vascular contractility and mitochondrial function is central to CVD pathogenesis. The progranulin gene (GRN) encodes glycoprotein progranulin (PGRN), a ubiquitous molecule with known anti-inflammatory property. However, the role of PGRN in CVD remains enigmatic. In this study, we sought to dissect the significance of PGRN in the regulation vascular contractility and investigate the interface between PGRN and mitochondrial quality.

Method

Our investigation utilized aortae from male and female C57BL6/J wild-type (PGRN+/+) and B6(Cg)-Grntm1.1Aidi/J (PGRN-/-) mice, encompassing wire myograph assays to assess vascular contractility and primary aortic vascular smooth muscle cells (VSMCs) for mechanistic insights.

Results

Our results showed suppression of contractile activity in PGRN-/- VSMCs and aorta, followed by reduced α-smooth muscle actin expression. Mechanistically, PGRN deficiency impaired mitochondrial oxygen consumption rate (OCR), complex I activity, mitochondrial turnover, and mitochondrial redox signaling, while restoration of PGRN levels in aortae from PGRN-/- mice via lentivirus delivery ameliorated contractility and boosted OCR. In addition, VSMC overexpressing PGRN displayed higher mitochondrial respiration and complex I activity accompanied by cellular hypercontractility. Furthermore, increased PGRN triggered lysosome biogenesis by regulating transcription factor EB and accelerated mitophagy flux in VSMC, while treatment with spermidine, an autophagy inducer, improved mitochondrial phenotype and enhanced vascular contractility. Finally, angiotensin II failed to induce vascular contractility in PGRN-/- suggesting a key role of PGRN to maintain the vascular tone.

Conclusion

Our findings suggest that PGRN preserves the vascular contractility via regulating mitophagy flux, mitochondrial complex I activity, and redox signaling. Therefore, loss of PGRN function appears as a pivotal risk factor in CVD development.

Vascular Biology of arterial aneurysms

OBJECTIVE

This review aims to analyze biomolecular and cellular events responsible for arterial aneurysm formation with particular attention to vascular remodeling that determines the initiation and the progression of arterial aneurysm, till rupture.

METHODS

This review was conducted searching libraries such as Web of Science, Scopus, ScienceDirect and Medline. Used keywords with various combinations were: "arterial aneurysms", "biology", "genetics", "proteomics", "molecular", "pathophysiology" and extracellular matrix" RESULTS: There are several genetic alterations responsible of syndromic and non-syndromic disease that predispose to aneurysm formation. ECM imbalance, mainly due to the alteration of vascular smooth muscle cells (VSMCs) homeostasis, overexpression of metalloproteinases (MPs) and cytokines activation, determines weakness of the arterial wall that dilates thus causing aneurysmal disease. Altered mechanotransduction in the ECM may also trigger and sustain anomalous cellular and biochemical signaling. Different cell population such as VSMCs, macrophages, perivascular adipose tissue (PVAT) cells, vascular wall resident stem cells (VWRSCs) are all involved at different levels CONCLUSIONS: Improving knowledge in vascular biology may help researchers and physicians in better targeting aneurysmal disease in order to better prevent and better treat such important disease.