Mitochondrial Isolevuglandins Contribute to Vascular Oxidative Stress and Mitochondria-Targeted Scavenger of Isolevuglandins Reduces Mitochondrial Dysfunction and Hypertension

Deacetylation mimetic mutation of mitochondrial SOD2 attenuates ANG II-induced hypertension by protecting against oxidative stress and inflammation

Almost one-half of adults have hypertension, and blood pressure is poorly controlled in a third of patients despite the use of multiple drugs, likely because of mechanisms that are not affected by current treatments. Hypertension is linked to oxidative stress; however, common antioxidants are ineffective. Hypertension is associated with inactivation of key intrinsic mitochondrial antioxidant, superoxide dismutase 2 (SOD2), due to hyperacetylation, but the role of specific SOD2 lysine residues has not been defined. Hypertension is associated with SOD2 acetylation at lysine 68, and we suggested that deacetylation mimetic mutation of K68 to arginine in SOD2 inhibits vascular oxidative stress and attenuates hypertension. To test this hypothesis, we have developed a new deacetylation mimetic SOD2-K68R mice. We performed in vivo studies in SOD2-K68R mice using angiotensin II (ANG II) model of vascular dysfunction and hypertension. ANG II infusion in wild-type mice induced vascular inflammation and oxidative stress and increased blood pressure to 160 mmHg. SOD2-K68R mutation completely prevented increase in mitochondrial superoxide, abrogated vascular oxidative stress, preserved endothelial nitric oxide production, protected vasorelaxation, and attenuated ANG II-induced hypertension. ANG II and cytokines contribute to vascular oxidative stress and hypertension. Treatment of wild-type aortas with ANG II and cytokines in organoid culture increased mitochondrial superoxide twofold, which was completely prevented in aortas isolated from SOD2-K68R mice. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and pathogenesis of hypertension. We conclude that strategies to reduce SOD2 acetylation may have therapeutic potential in the treatment of vascular dysfunction and hypertension.NEW & NOTEWORTHY Essential hypertension is associated with hyperacetylation of key mitochondrial antioxidant SOD2; however, the pathophysiological role of SOD2 acetylation has not been defined. Our animal study of angiotensin II hypertension model shows that deacetylation mimetic SOD2-K68R mutation prevents pathogenic increase in vascular mitochondrial superoxide, abrogates vascular oxidative stress, preserves endothelial nitric oxide, protects endothelial-dependent vasorelaxation, and attenuates hypertension. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and the pathogenesis of hypertension.

Reactive oxygen species in hypertension

Hypertension is a leading risk factor for stroke, heart disease and chronic kidney disease. Multiple interacting factors and organ systems increase blood pressure and cause target-organ damage. Among the many molecular elements involved in the development of hypertension are reactive oxygen species (ROS), which influence cellular processes in systems that contribute to blood pressure elevation (such as the cardiovascular, renal, immune and central nervous systems, or the renin-angiotensin-aldosterone system). Dysregulated ROS production (oxidative stress) is a hallmark of hypertension in humans and experimental models. Of the many ROS-generating enzymes, NADPH oxidases are the most important in the development of hypertension. At the cellular level, ROS influence signalling pathways that define cell fate and function. Oxidative stress promotes aberrant redox signalling and cell injury, causing endothelial dysfunction, vascular damage, cardiovascular remodelling, inflammation and renal injury, which are all important in both the causes and consequences of hypertension. ROS scavengers reduce blood pressure in almost all experimental models of hypertension; however, clinical trials of antioxidants have yielded mixed results. In this Review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in hypertension. We focus on cellular sources of ROS, molecular mechanisms of oxidative stress and alterations in redox signalling in organ systems, and their contributions to hypertension.

LNK/SH2B3 loss of function increases susceptibility to murine and human atrial fibrillation

AIMS

The lymphocyte adaptor protein (LNK) is a negative regulator of cytokine and growth factor signalling. The rs3184504 variant in SH2B3 reduces LNK function and is linked to cardiovascular, inflammatory, and haematologic disorders, including stroke. In mice, deletion of Lnk causes inflammation and oxidative stress. We hypothesized that Lnk-/- mice are susceptible to atrial fibrillation (AF) and that rs3184504 is associated with AF and AF-related stroke in humans. During inflammation, reactive lipid dicarbonyls are the major components of oxidative injury, and we further hypothesized that these mediators are critical drivers of the AF substrate in Lnk-/- mice.

METHODS AND RESULTS

Lnk-/- or wild-type (WT) mice were treated with vehicle or 2-hydroxybenzylamine (2-HOBA), a dicarbonyl scavenger, for 3 months. Compared with WT, Lnk-/- mice displayed increased AF duration that was prevented by 2-HOBA. In the Lnk-/- atria, action potentials were prolonged with reduced transient outward K+ current, increased late Na+ current, and reduced peak Na+ current, pro-arrhythmic effects that were inhibited by 2-HOBA. Mitochondrial dysfunction, especially for Complex I, was evident in Lnk-/- atria, while scavenging lipid dicarbonyls prevented this abnormality. Tumour necrosis factor-α (TNF-α) and interleukin-1 beta (IL-1β) were elevated in Lnk-/- plasma and atrial tissue, respectively, both of which caused electrical and bioenergetic remodelling in vitro. Inhibition of soluble TNF-α prevented electrical remodelling and AF susceptibility, while IL-1β inhibition improved mitochondrial respiration but had no effect on AF susceptibility. In a large database of genotyped patients, rs3184504 was associated with AF, as well as AF-related stroke.

CONCLUSION

These findings identify a novel role for LNK in the pathophysiology of AF in both experimental mice and humans. Moreover, reactive lipid dicarbonyls are critical to the inflammatory AF substrate in Lnk-/- mice and mediate the pro-arrhythmic effects of pro-inflammatory cytokines, primarily through electrical remodelling.

Critical Role of Mitochondrial Fatty Acid Metabolism in Normal Cell Function and Pathological Conditions

There is a "popular" belief that a fat-free diet is beneficial, supported by the scientific dogma indicating that high levels of fatty acids promote many pathological metabolic, cardiovascular, and neurodegenerative conditions. This dogma pressured scientists not to recognize the essential role of fatty acids in cellular metabolism and focus on the detrimental effects of fatty acids. In this work, we critically review several decades of studies and recent publications supporting the critical role of mitochondrial fatty acid metabolism in cellular homeostasis and many pathological conditions. Fatty acids are the primary fuel source and essential cell membrane building blocks from the origin of life. The essential cell membranes phospholipids were evolutionarily preserved from the earlier bacteria in human subjects. In the past century, the discovery of fatty acid metabolism was superseded by the epidemic growth of metabolic conditions and cardiovascular diseases. The association of fatty acids and pathological conditions is not due to their "harmful" effects but rather the result of impaired fatty acid metabolism and abnormal lifestyle. Mitochondrial dysfunction is linked to impaired metabolism and drives multiple pathological conditions. Despite metabolic flexibility, the loss of mitochondrial fatty acid oxidation cannot be fully compensated for by other sources of mitochondrial substrates, such as carbohydrates and amino acids, resulting in a pathogenic accumulation of long-chain fatty acids and a deficiency of medium-chain fatty acids. Despite popular belief, mitochondrial fatty acid oxidation is essential not only for energy-demanding organs such as the heart, skeletal muscle, and kidneys but also for metabolically "inactive" organs such as endothelial and epithelial cells. Recent studies indicate that the accumulation of long-chain fatty acids in specific organs and tissues support the impaired fatty acid oxidation in cell- and tissue-specific fashion. This work, therefore, provides a basis to challenge these established dogmas and articulate the need for a paradigm shift from the "pathogenic" role of fatty acids to the critical role of fatty acid oxidation. This is important to define the causative role of impaired mitochondrial fatty acid oxidation in specific pathological conditions and develop novel therapeutic approaches targeting mitochondrial fatty acid metabolism.

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.

Isolevuglandins Promote Mitochondrial Dysfunction and Electrophysiologic Abnormalities in Atrial Cardiomyocytes

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, yet the cellular and molecular mechanisms underlying the AF substrate remain unclear. Isolevuglandins (IsoLGs) are highly reactive lipid dicarbonyl products that mediate oxidative stress-related injury. In murine hypertension, the lipid dicarbonyl scavenger 2-hydroxybenzylamine (2-HOBA) reduced IsoLGs and AF susceptibility. We hypothesized that IsoLGs mediate detrimental pathophysiologic effects in atrial cardiomyocytes that promote the AF substrate. Using Seahorse XFp extracellular flux analysis and a luminescence assay, IsoLG exposure suppressed intracellular ATP production in atrial HL-1 cardiomyocytes. IsoLGs caused mitochondrial dysfunction, with reduced mitochondrial membrane potential, increased mitochondrial reactive oxygen species (ROS) with protein carbonylation, and mitochondrial DNA damage. Moreover, they generated cytosolic preamyloid oligomers previously shown to cause similar detrimental effects in atrial cells. In mouse atrial and HL-1 cells, patch clamp experiments demonstrated that IsoLGs rapidly altered action potentials (AP), implying a direct effect independent of oligomer formation by reducing the maximum Phase 0 upstroke slope and shortening AP duration due to ionic current modifications. IsoLG-mediated mitochondrial and electrophysiologic abnormalities were blunted or totally prevented by 2-HOBA. These findings identify IsoLGs as novel mediators of oxidative stress-dependent atrial pathophysiology and support the investigation of dicarbonyl scavengers as a novel therapeutic approach to prevent AF.

Empowering mitochondrial metabolism: Exploring L-lactate supplementation as a promising therapeutic approach for metabolic syndrome

Mitochondrial dysfunction plays a critical role in the pathogenesis of metabolic syndrome (MetS), affecting various cell types and organs. In MetS animal models, mitochondria exhibit decreased quality control, characterized by abnormal morphological structure, impaired metabolic activity, reduced energy production, disrupted signaling cascades, and oxidative stress. The aberrant changes in mitochondrial function exacerbate the progression of metabolic syndrome, setting in motion a pernicious cycle. From this perspective, reversing mitochondrial dysfunction is likely to become a novel and powerful approach for treating MetS. Unfortunately, there are currently no effective drugs available in clinical practice to improve mitochondrial function. Recently, L-lactate has garnered significant attention as a valuable metabolite due to its ability to regulate mitochondrial metabolic processes and function. It is highly likely that treating MetS and its related complications can be achieved by correcting mitochondrial homeostasis disorders. In this review, we comprehensively discuss the complex relationship between mitochondrial function and MetS and the involvement of L-lactate in regulating mitochondrial metabolism and associated signaling pathways. Furthermore, it highlights recent findings on the involvement of L-lactate in common pathologies of MetS and explores its potential clinical application and further prospects, thus providing new insights into treatment possibilities for MetS.

Associations between plasma metal/metalloid mixtures and the risk of central obesity: A prospective cohort study of Chinese adults

Central obesity has increased rapidly over the past decade and posed a substantial disease burden worldwide. Exposure to metals/metalloids has been acknowledged to be involved in the development of central obesity through regulation of cortisol, insulin resistance, and glucocorticoid receptor reduction. Despite the importance, it is lack of prospective study which comprehensively evaluate the relations between multiple metals exposure and central obesity. We explored the prospective associations of plasma metal concentrations with central obesity in a prospective study of the Dongfeng-Tongji cohort. The present study included 2127 participants with a 6.87-year mean follow-up duration. We measured 23 plasma metal/metalloid concentrations at baseline. The associations between metals and incident central obesity were examined utilizing the Cox proportional hazard regression in single and multiple metals models. Additionally, we applied elastic net (ENET), Bayesian kernel machine regression (BKMR), plasma metal score (PMS), and quantile-based g-computation (Qgcomp) models to explore the joint associations of metal mixtures with central obesity. After adjusting potential confounders, we found significant associations of plasma manganese (Mn) and thallium (Tl) concentrations with a higher risk of central obesity, whereas plasma rubidium (Rb) concentration was associated with a lower risk of central obesity both in single and multiple metals models (all FDR <0.05). The ENET and Qqcomp models verified similar metals (Mn, Rb, and Tl) as important predictors for central obesity. The results of both BKMR model and PMS suggested cumulative exposure to metal mixtures was associated with a higher risk of central obesity. Our findings suggested that co-exposure to metals was associated with a higher risk of central obesity. This study expands our knowledge that the management of metals/metalloids exposure may be beneficial for the prevention of new-onset central obesity, which may subsequently alleviate the disease burden of late-life health outcomes.

Mitophagy in hypertension-mediated organ damage

Hypertension constitutes a pervasive chronic ailment on a global scale, frequently inflicting damage upon vital organs, such as the heart, blood vessels, kidneys, brain, and others. And this is a complex clinical dilemma that requires immediate attention. The mitochondria assume a crucial function in the generation of energy, and it is of utmost importance to eliminate any malfunctioning or surplus mitochondria to uphold intracellular homeostasis. Mitophagy is considered a classic example of selective autophagy, an important component of mitochondrial quality control, and is closely associated with many physiological and pathological processes. The ubiquitin-dependent pathway, facilitated by PINK1/Parkin, along with the ubiquitin-independent pathway, orchestrated by receptor proteins such as BNIP3, NIX, and FUNDC1, represent the extensively investigated mechanisms underlying mitophagy. In recent years, research has increasingly shown that mitophagy plays an important role in organ damage associated with hypertension. Exploring the molecular mechanisms of mitophagy in hypertension-mediated organ damage could represent a critical avenue for future research in the development of innovative therapeutic modalities. Therefore, this article provides a comprehensive review of the impact of mitophagy on organ damage due to hypertension.

Cellular mechanisms and molecular pathways linking bitter taste receptor signalling to cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction in heart diseases

Heart diseases and related complications constitute a leading cause of death and socioeconomic threat worldwide. Despite intense efforts and research on the pathogenetic mechanisms of these diseases, the underlying cellular and molecular mechanisms are yet to be completely understood. Several lines of evidence indicate a critical role of inflammatory and oxidative stress responses in the development and progression of heart diseases. Nevertheless, the molecular machinery that drives cardiac inflammation and oxidative stress is not completely known. Recent data suggest an important role of cardiac bitter taste receptors (TAS2Rs) in the pathogenetic mechanism of heart diseases. Independent groups of researchers have demonstrated a central role of TAS2Rs in mediating inflammatory, oxidative stress responses, autophagy, impulse generation/propagation and contractile activities in the heart, suggesting that dysfunctional TAS2R signalling may predispose to cardiac inflammatory and oxidative stress disorders, characterised by contractile dysfunction and arrhythmia. Moreover, cardiac TAS2Rs act as gateway surveillance units that monitor and detect toxigenic or pathogenic molecules, including microbial components, and initiate responses that ultimately culminate in protection of the host against the aggression. Unfortunately, however, the molecular mechanisms that link TAS2R sensing of the cardiac milieu to inflammatory and oxidative stress responses are not clearly known. Therefore, we sought to review the possible role of TAS2R signalling in the pathophysiology of cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction in heart diseases. Potential therapeutic significance of targeting TAS2R or its downstream signalling molecules in cardiac inflammation, oxidative stress, arrhythmia and contractile dysfunction is also discussed.

Molecular Mechanisms of Mitochondrial Quality Control in Ischemic Cardiomyopathy

Ischemic cardiomyopathy (ICM) is a special type of coronary heart disease or an advanced stage of the disease, which is related to the pathological mechanism of primary dilated cardiomyopathy. Ischemic cardiomyopathy mainly occurs in the long-term myocardial ischemia, resulting in diffuse myocardial fibrosis. This in turn affects the cardiac ejection function, resulting in a significant impact on myocardial systolic and diastolic function, resulting in a decrease in the cardiac ejection fraction. The pathogenesis of ICM is closely related to coronary heart disease. Mainly due to coronary atherosclerosis caused by coronary stenosis or vascular occlusion, causing vascular inflammatory lesions and thrombosis. As the disease progresses, it leads to long-term myocardial ischemia and eventually ICM. The pathological mechanism is mainly related to the mechanisms of inflammation, myocardial hypertrophy, fibrosis and vascular remodeling. Mitochondria are organelles with a double-membrane structure, so the composition of the mitochondrial outer compartment is basically similar to that of the cytoplasm. When ischemia-reperfusion induces a large influx of calcium into the cell, the concentration of calcium ions in the mitochondrial outer compartment also increases. The subsequent opening of the membrane permeability transition pore in the inner mitochondrial membrane and the resulting calcium overload induces the homeostasis of cardiomyocytes and activates the mitochondrial pathway of apoptosis. Mitochondrial Quality Control (MQC), as an important mechanism for regulating mitochondrial function in cardiomyocytes, affects the morphological structure/function and lifespan of mitochondria. In this review, we discuss the role of MQC (including mitophagy, mitochondrial dynamics, and mitochondrial biosynthesis) in the pathogenesis of ICM and provide important evidence for targeting MQC for ICM.

FoxO3 Regulates the Progress and Development of Aging and Aging-Related Diseases

Aging is an inevitable risk factor for many diseases, including cardiovascular diseases, neurodegenerative diseases, cancer, and diabetes. Investigation into the molecular mechanisms involved in aging and longevity will benefit the treatment of age-dependent diseases and the development of preventative medicine for agingrelated diseases. Current evidence has revealed that FoxO3, encoding the transcription factor (FoxO)3, a key transcription factor that integrates different stimuli in the intrinsic and extrinsic pathways and is involved in cell differentiation, protein homeostasis, stress resistance and stem cell status, plays a regulatory role in longevity and in age-related diseases. However, the precise mechanisms by which the FoxO3 transcription factor modulates aging and promotes longevity have been unclear until now. Here, we provide a brief overview of the mechanisms by which FoxO3 mediates signaling in pathways involved in aging and aging-related diseases, as well as the current knowledge on the role of the FoxO3 transcription factor in the human lifespan and its clinical prospects. Ultimately, we conclude that FoxO3 signaling pathways, including upstream and downstream molecules, may be underlying therapeutic targets in aging and age-related diseases.

Oxidative Regulation of Vascular Cav1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders

Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca²⁺ (Ca_v1.2) channel in small arteries and arterioles plays an essential role in regulating Ca²⁺ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Ca_v1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Ca_v1.2 and potential roles of ROS-mediated Ca_v1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.

Dicarbonyl-modified lipoproteins contribute to proteinuric kidney injury

Lipoprotein modification by reactive dicarbonyls, including isolevuglandin (IsoLG), produces dysfunctional particles. Kidneys participate in lipoprotein metabolism, including tubular uptake. However, the process beyond the proximal tubule is unclear, as is the effect of kidney injury on this pathway. We found that patients and animals with proteinuric injury have increased urinary apolipoprotein AI (apoAI), IsoLG, and IsoLG adduct enrichment of the urinary apoAI fraction compared with other proteins. Proteinuric mice, induced by podocyte-specific injury, showed more tubular absorption of IsoLG-apoAI and increased expression of lipoprotein transporters in proximal tubular cells compared with uninjured animals. Renal lymph reflects composition of the interstitial compartment and showed increased apoAI and IsoLG in proteinuric animals, supporting a tubular cell-interstitium-lymph pathway for renal handling of lipoproteins. IsoLG-modified apoAI was not only a marker of renal injury but also directly damaged renal cells. IsoLG-apoAI increased inflammatory cytokines in cultured tubular epithelial cells (TECs), activated lymphatic endothelial cells (LECs), and caused greater contractility of renal lymphatic vessels than unmodified apoAI. In vivo, inhibition of IsoLG by a dicarbonyl scavenger reduced both albuminuria and urinary apoAI and decreased TEC and LEC injury, lymphangiogenesis, and interstitial fibrosis. Our results indicate that IsoLG-modified apoAI is, to our knowledge, a novel pathogenic mediator and therapeutic target in kidney disease.

Regulation of mitochondrial dysfunction induced cell apoptosis is a potential therapeutic strategy for herbal medicine to treat neurodegenerative diseases

Neurodegenerative disease is a progressive neurodegeneration caused by genetic and environmental factors. Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD) are the three most common neurodegenerative diseases clinically. Unfortunately, the incidence of neurodegenerative diseases is increasing year by year. However, the current available drugs have poor efficacy and large side effects, which brings a great burden to the patients and the society. Increasing evidence suggests that occurrence and development of the neurodegenerative diseases is closely related to the mitochondrial dysfunction, which can affect mitochondrial biogenesis, mitochondrial dynamics, as well as mitochondrial mitophagy. Through the disruption of mitochondrial homeostasis, nerve cells undergo varying degrees of apoptosis. Interestingly, it has been shown in recent years that the natural agents derived from herbal medicines are beneficial for prevention/treatment of neurodegenerative diseases via regulation of mitochondrial dysfunction. Therefore, in this review, we will focus on the potential therapeutic agents from herbal medicines for treating neurodegenerative diseases via suppressing apoptosis through regulation of mitochondrial dysfunction, in order to provide a foundation for the development of more candidate drugs for neurodegenerative diseases from herbal medicine.

Disparate Roles of Oxidative Stress in Rostral Ventrolateral Medulla in Age-Dependent Susceptibility to Hypertension Induced by Systemic l-NAME Treatment in Rats

This study aims to investigate whether tissue oxidative stress in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons reside, plays an active role in age-dependent susceptibility to hypertension in response to nitric oxide (NO) deficiency induced by systemic l-NAME treatment, and to decipher the underlying molecular mechanisms. Systolic blood pressure (SBP) and heart rate (HR) in conscious rats were recorded, along with measurements of plasma and RVLM level of NO and reactive oxygen species (ROS), and expression of mRNA and protein involved in ROS production and clearance, in both young and adult rats subjected to intraperitoneal (i.p.) infusion of l-NAME. Pharmacological treatments were administered by oral gavage or intracisternal infusion. Gene silencing of target mRNA was made by bilateral microinjection into RVLM of lentivirus that encodes a short hairpin RNA (shRNA) to knock down gene expression of NADPH oxidase activator 1 (Noxa1). We found that i.p. infusion of l-NAME resulted in increases in SBP, sympathetic neurogenic vasomotor activity, and plasma norepinephrine levels in an age-dependent manner. Systemic l-NAME also evoked oxidative stress in RVLM of adult, but not young rats, accompanied by augmented enzyme activity of NADPH oxidase and reduced mitochondrial electron transport enzyme activities. Treatment with L-arginine via oral gavage or infusion into the cistern magna (i.c.), but not i.c. tempol or mitoQ₁₀, significantly offset the l-NAME-induced hypertension in young rats. On the other hand, all treatments appreciably reduced l-NAME-induced hypertension in adult rats. The mRNA microarray analysis revealed that four genes involved in ROS production and clearance were differentially expressed in RVLM in an age-related manner. Of them, Noxa1, and GPx2 were upregulated and Duox2 and Ucp3 were downregulated. Systemic l-NAME treatment caused greater upregulation of Noxa1, but not Ucp3, mRNA expression in RVLM of adult rats. Gene silencing of Noxa1 in RVLM effectively alleviated oxidative stress and protected adult rats against l-NAME-induced hypertension. These data together suggest that hypertension induced by systemic l-NAME treatment in young rats is mediated primarily by NO deficiency that occurs both in vascular smooth muscle cells and RVLM. On the other hand, enhanced augmentation of oxidative stress in RVLM may contribute to the heightened susceptibility of adult rats to hypertension induced by systemic l-NAME treatment.

Association of circulating branched-chain amino acids with risk of moyamoya disease

Objective

Branched-Chain Amino Acids (BCAAs) has been identified as a risk factor for circulatory disease. Nevertheless, the effects and mechanisms of BCAAs on the risk of moyamoya disease (MMD) remain unrecognized. Hence, we aimed to elucidate the association between circulating BCAAs and the risk of MMD and clinical subtypes.

Methods

We conducted a case-control study of 360 adult MMD patients and 89 matched healthy controls consecutively recruited between September 2020 and December 2021. Serum level of BCAAs was quantified by liquid chromatography-mass spectrometry. The associations between BCAAs and risk of MMD were evaluated.

Results

Increased level of serum BCAAs was observed in MMD patients (P < 0.001). After adjusting for traditional confounders, the elevated BCAAs level was significantly associated with the risk of MMD (Q4 vs. Q1: odds ratio, 3.10 [95% CI, 1.29–7.50]). The risk of subtypes in MMD also increased with each increment in the quartiles of BCAAs. Furthermore, BCAAs offered substantial improvement in risk reclassification and discrimination for MMD and subtypes.

Conclusion

Higher level of circulating BCAAs was associated with increased risk of MMD and clinical subtypes. This study will help to elucidate the pathogenesis of MMD, which may provide the support for facilitating the treatments and preventions.

Association between Quantitative Classification of Renal Surface Nodularity and Early Renal Injury in Patients with Arterial Hypertension

Background

This study sought to explore the association between quantitative classification of renal surface nodularity (qRSN) based on computed tomography (CT) imaging and early renal injury (ERI) in patients with arterial hypertension.

Methods

A total of 143 patients with a history of hypertension were retrospectively enrolled; clinical information (age, sex, hypertension grade, and hypertension course), laboratory tests, and qRSN were collected or assessed. The subjects were divided into an ERI group (n = 60) or a control group (CP, n = 83) according to ERI diagnosis based on the following criteria: cystatin C > 1.02 mg/L. Univariate analysis and multiple logistic regression were used to assess the association between ERI and qRSN. A receiver operating characteristic curve (ROC) was performed to compare multiple logistic regression models with or without qRSN for differentiating the ERI group from the control group.

Results

In univariate analysis, hypertension grade, hypertension course, triglycerides (TG), and qRSN were related to ERI in patients with arterial hypertension (all P < 0.1), with strong interrater agreement of qRSN. Multiple logistic regression analysis showed an area under the ROC curve of 0.697 in the model without qRSN and 0.790 in the model with qRSN, which was significantly different (Z = 2.314, P=0.021).

Conclusion

CT imaging-based qRSN was associated with ERI in patients with arterial hypertension and may be an imaging biomarker of early renal injury.

Mitochondrial deacetylase Sirt3 in vascular dysfunction and hypertension

PURPOSE OF REVIEW

Hypertension is a multifactorial disorder involving perturbations of the vasculature, the kidney, and the central nervous system. Hypertension represents a major risk factor for stroke, myocardial infarction, and heart failure. Despite treatment with multiple drugs, 37% of hypertensive patients remain hypertensive, likely due to the mechanisms contributing to blood pressure elevation that are not affected by current treatments. This review focuses on recently described novel role of mitochondrial deacetylase Sirt3 in vascular dysfunction and hypertension.

RECENT FINDINGS

In the past several years, we have shown that the mitochondria are dysfunctional in hypertension; however, the role of mitochondria in the pathogenesis of hypertension remains elusive. We recently showed that patients with essential hypertension have decreased levels of the mitochondrial deacetylase Sirt3 leading to hyperacetylation of mitochondrial proteins. There is likely a causative role. Indeed, genetic deletion of Sirt3 in mice promotes vascular dysfunction and hypertension. Sirt3 depletion promotes endothelial dysfunction, increases smooth muscle cell hypertrophy, instigates vascular inflammation, and induces age-dependent hypertension.

SUMMARY

Sirt3 is critical for vascular cell homeostasis, however, multiple risk factors impair Sirt3 leading to mitochondrial dysfunction and vascular dysregulation which contribute to hypertension and end-organ injury. Targeting Sirt3 may represent novel therapeutic approach to improve treatment of vascular dysfunction and reduce hypertension.

Oxidative Stress and Hypertension

A link between oxidative stress and hypertension has been firmly established in multiple animal models of hypertension but remains elusive in humans. While initial studies focused on inactivation of nitric oxide by superoxide, our understanding of relevant reactive oxygen species (superoxide, hydrogen peroxide, and peroxynitrite) and how they modify complex signaling pathways to promote hypertension has expanded significantly. In this review, we summarize recent advances in delineating the primary and secondary sources of reactive oxygen species (nicotinamide adenine dinucleotide phosphate oxidases, uncoupled endothelial nitric oxide synthase, endoplasmic reticulum, and mitochondria), the posttranslational oxidative modifications they induce on protein targets important for redox signaling, their interplay with endogenous antioxidant systems, and the role of inflammasome activation and endoplasmic reticular stress in the development of hypertension. We highlight how oxidative stress in different organ systems contributes to hypertension, describe new animal models that have clarified the importance of specific proteins, and discuss clinical studies that shed light on how these processes and pathways are altered in human hypertension. Finally, we focus on the promise of redox proteomics and systems biology to help us fully understand the relationship between ROS and hypertension and their potential for designing and evaluating novel antihypertensive therapies.

Vascular Stress Signaling in Hypertension

Cells respond to stress by activating a variety of defense signaling pathways, including cell survival and cell death pathways. Although cell survival signaling helps the cell to recover from acute insults, cell death or senescence pathways induced by chronic insults can lead to unresolved pathologies. Arterial hypertension results from chronic physiological maladaptation against various stressors represented by abnormal circulating or local neurohormonal factors, mechanical stress, intracellular accumulation of toxic molecules, and dysfunctional organelles. Hypertension and aging share common mechanisms that mediate or prolong chronic cell stress, such as endoplasmic reticulum stress and accumulation of protein aggregates, oxidative stress, metabolic mitochondrial stress, DNA damage, stress-induced senescence, and proinflammatory processes. This review discusses common adaptive signaling mechanisms against these stresses including unfolded protein responses, antioxidant response element signaling, autophagy, mitophagy, and mitochondrial fission/fusion, STING (signaling effector stimulator of interferon genes)-mediated responses, and activation of pattern recognition receptors. The main molecular mechanisms by which the vasculature copes with hypertensive and aging stressors are presented and recent advancements in stress-adaptive signaling mechanisms as well as potential therapeutic targets are discussed.