Clinically relevant high levels of human C-reactive protein induces endothelial dysfunction and hypertension by inhibiting the AMPK-eNOS axis

Przewaquinone A inhibits Angiotensin II-induced endothelial diastolic dysfunction activation of AMPK

BACKGROUND

Endothelial dysfunction (ED), characterized by markedly reduced nitric oxide (NO) bioavailability, vasoconstriction, and a shift toward a proinflammatory and prothrombotic state, is an important contributor to hypertension, atherosclerosis, and other cardiovascular diseases. Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is widely involved in cardiovascular development. Przewaquinone A (PA), a lipophilic diterpene quinone extracted from Salvia przewalskii Maxim, inhibits vascular contraction.

PURPOSE

Herein, the goal was to explore the protective effect of PA on ED in vivo and in vitro, as well as the underlying mechanisms.

METHODS

A human umbilical vein endothelial cell (HUVEC) model of ED induced by angiotensin II (AngII) was used for in vitro observations. Levels of AMPK, endothelial nitric oxide synthase (eNOS), vascular cell adhesion molecule-1 (VCAM-1), nitric oxide (NO), and endothelin-1 (ET-1) were detected by western blotting and ELISA. A mouse model of hypertension was established by continuous infusion of AngII (1000 ng/kg/min) for 4 weeks using osmotic pumps. Following PA and/or valsartan administration, NO and ET-1 levels were measured. The levels of AMPK signaling-related proteins in the thoracic aorta were evaluated by immunohistochemistry. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were measured using the tail cuff method. Isolated aortic vascular tone measurements were used to evaluate the vasodilatory function in mice. Molecular docking, molecular dynamics, and surface plasmon resonance imaging (SPRi) were used to confirm AMPK and PA interactions.

RESULTS

PA inhibited AngII-induced vasoconstriction and vascular adhesion as well as activated AMPK signaling in a dose-dependent manner. Moreover, PA markedly suppressed blood pressure, activated vasodilation in mice following AngII stimulation, and promoted the activation of AMPK signaling. Furthermore, molecular simulations and SPRi revealed that PA directly targeted AMPK. AMPK inhibition partly abolished the protective effects of PA against endothelial dysfunction.

CONCLUSION

PA activates AMPK and ameliorates endothelial dysfunction during hypertension.

The Potential Role of C-Reactive Protein in Metabolic-Dysfunction-Associated Fatty Liver Disease and Aging

Nonalcoholic fatty liver disease (NAFLD), recently redefined as metabolic-dysfunction-associated fatty liver disease (MASLD), is liver-metabolism-associated steatohepatitis caused by nonalcoholic factors. NAFLD/MASLD is currently the most prevalent liver disease in the world, affecting one-fourth of the global population, and its prevalence increases with age. Current treatments are limited; one important reason hindering drug development is the insufficient understanding of the onset and pathogenesis of NAFLD/MASLD. C-reactive protein (CRP), a marker of inflammation, has been linked to NAFLD and aging in recent studies. As a conserved acute-phase protein, CRP is widely characterized for its host defense functions, but the link between CRP and NAFLD/MASLD remains unclear. Herein, we discuss the currently available evidence for the involvement of CRP in MASLD to identify areas where further research is needed. We hope this review can provide new insights into the development of aging-associated NAFLD biomarkers and suggest that modulation of CRP signaling is a potential therapeutic target.

Hypertension and renal disease programming: focus on the early postnatal period

The developmental origin of hypertension and renal disease is a concept highly supported by strong evidence coming from both human and animal studies. During development there are periods in which the organs are more vulnerable to stressors. Such periods of susceptibility are also called 'sensitive windows of exposure'. It was shown that as earlier an adverse event occurs; the greater are the consequences for health impairment. However, evidence show that the postnatal period is also quite important for hypertension and renal disease programming, especially in rodents because they complete nephrogenesis postnatally, and it is also important during preterm human birth. Considering that the developing kidney is vulnerable to early-life stressors, renal programming is a key element in the developmental programming of hypertension and renal disease. The purpose of this review is to highlight the great number of studies, most of them performed in animal models, showing the broad range of stressors involved in hypertension and renal disease programming, with a particular focus on the stressors that occur during the early postnatal period. These stressors mainly include undernutrition or specific nutritional deficits, chronic behavioral stress, exposure to environmental chemicals, and pharmacological treatments that affect some important factors involved in renal physiology. We also discuss the common molecular mechanisms that are activated by the mentioned stressors and that promote the appearance of these adult diseases, with a brief description on some reprogramming strategies, which is a relatively new and promising field to treat or to prevent these diseases.

Endothelial PDGF-BB/PDGFR-β signaling promotes osteoarthritis by enhancing angiogenesis-dependent abnormal subchondral bone formation

The mechanisms that coordinate the shift from joint homeostasis to osteoarthritis (OA) remain unknown. No pharmacological intervention can currently prevent the progression of osteoarthritis. Accumulating evidence has shown that subchondral bone deterioration is a primary trigger for overlying cartilage degeneration. We previously found that H-type vessels modulate aberrant subchondral bone formation during the pathogenesis of OA. However, the mechanism responsible for the elevation of H-type vessels in OA is still unclear. Here, we found that PDGFR-β expression, predominantly in the CD31^hiEmcn^hi endothelium, was substantially elevated in subchondral bones from OA patients and rodent OA models. A mouse model of OA with deletion of PDGFR-β in endothelial cells (ECs) exhibited fewer H-type vessels, ameliorated subchondral bone deterioration and alleviated overlying cartilage degeneration. Endothelial PDGFR-β promotes angiogenesis through the formation of the PDGFR-β/talin1/FAK complex. Notably, endothelium-specific inhibition of PDGFR-β by local injection of AAV9 in subchondral bone effectively attenuated the pathogenesis of OA compared with that of the vehicle-treated controls. Based on the results from this study, targeting PDGFR-β is a novel and promising approach for the prevention or early treatment of OA.

SIRT3-AMPK signaling pathway as a protective target in endothelial dysfunction of early sepsis

Extensive vascular endothelial dysfunction usually occurs in sepsis, resulting in high mortality. The purpose of this study was therefore to investigate the role of AMP-dependent protein kinase (AMPK) in the aortic endothelial dysfunction of early sepsis in mice, and the relationship between AMPK and Sirtuin3 (SIRT3). Cecal ligation and puncture (CLP) surgery was performed to establish a mouse sepsis model, and human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) to mimic a sepsis model in vitro. We suppressed and increased the activities of AMPK with Dorsomorphin (CC) and Acadesine (AICAR), respectively. 3-TYP (SIRT3 inhibitor) and Honokiol (SIRT3 agonist) were used to alter SIRT3 activity. Then, the inflammatory and endothelial function parameters of the vascular tissue and survival rate were determined. In vivo, the expression of Ser1177 phosphorylation of endothelial nitric oxide synthase (p-eNOS), endothelium-dependent relaxation function, and survival decreased (P < 0.05), while NF-κB and NLRP3 pathways were activated in CLP-induced early sepsis (P < 0.05). Moreover, activation of AMPK significantly reversed the reduction of p-eNOS expression (P < 0.05), prevented endothelial dysfunction (P < 0.05), deactivated NF-κB and NLRP3 pathways (P < 0.05), and improved survival (P < 0.05) in septic mice. However, AMPK inhibition led to opposite effects (P < 0.05). In addition, changing the activity of AMPK had little effect on SIRT3 expression (P > 0.05), while the expression of p-AMPK varied with the inhibition or activation of SIRT3 (P < 0.05), which was further demonstrated using in vitro experiments. Together, the results showed that the SIRT3-AMPK signaling pathway played an important role in inhibiting vascular inflammation and endothelial dysfunction during early sepsis.

Activation of Nrf2 by Lithospermic Acid Ameliorates Myocardial Ischemia and Reperfusion Injury by Promoting Phosphorylation of AMP-Activated Protein Kinase α (AMPKα)

Background: As a plant-derived polycyclic phenolic carboxylic acid isolated from Salvia miltiorrhiza, lithospermic acid (LA) has been identified as the pharmacological management for neuroprotection and hepatoprotection. However, the role and mechanism of lithospermic acid in the pathological process of myocardial ischemia-reperfusion injury are not fully revealed. Methods: C57BL/6 mice were subjected to myocardial ischemia and reperfusion (MI/R) surgery and pretreated by LA (50 mg/kg, oral gavage) for six consecutive days before operation. The in vitro model of hypoxia reoxygenation (HR) was induced by hypoxia for 24 h and reoxygenation for 6 h in H9C2 cells, which were subsequently administrated with lithospermic acid (100 μM). Nrf2 siRNA and dorsomorphin (DM), an inhibitor of AMPKα, were used to explore the function of AMPKα/Nrf2 in LA-mediated effects. Results: LA pretreatment attenuates infarct area and decreases levels of TnT and CK-MB in plasm following MI/R surgery in mice. Echocardiography and hemodynamics indicate that LA suppresses MI/R-induced cardiac dysfunction. Moreover, LA ameliorates oxidative stress and cardiomyocytes apoptosis following MI/R operation or HR in vivo and in vitro. In terms of mechanism, LA selectively activates eNOS, simultaneously increases nuclear translocation and phosphorylation of Nrf2 and promotes Nrf2/HO-1 pathway in vivo and in vitro, while cardioprotection of LA is abolished by pharmacological inhibitor of AMPK or Nrf2 siRNA in H9C2 cells. Conclusion: LA protects against MI/R-induced cardiac injury by promoting eNOS and Nrf2/HO-1 signaling via phosphorylation of AMPKα.

Metformin in cardiovascular diabetology: a focused review of its impact on endothelial function

As a first-line treatment for diabetes, the insulin-sensitizing biguanide, metformin, regulates glucose levels and positively affects cardiovascular function in patients with diabetes and cardiovascular complications. Endothelial dysfunction (ED) represents the primary pathological change of multiple vascular diseases, because it causes decreased arterial plasticity, increased vascular resistance, reduced tissue perfusion and atherosclerosis. Caused by “biochemical injury”, ED is also an independent predictor of cardiovascular events. Accumulating evidence shows that metformin improves ED through liver kinase B1 (LKB1)/5'-adenosine monophosphat-activated protein kinase (AMPK) and AMPK-independent targets, including nuclear factor-kappa B (NF-κB), phosphatidylinositol 3 kinase-protein kinase B (PI3K-Akt), endothelial nitric oxide synthase (eNOS), sirtuin 1 (SIRT1), forkhead box O1 (FOXO1), krüppel-like factor 4 (KLF4) and krüppel-like factor 2 (KLF2). Evaluating the effects of metformin on endothelial cell functions would facilitate our understanding of the therapeutic potential of metformin in cardiovascular diabetology (including diabetes and its cardiovascular complications). This article reviews the physiological and pathological functions of endothelial cells and the intact endothelium, reviews the latest research of metformin in the treatment of diabetes and related cardiovascular complications, and focuses on the mechanism of action of metformin in regulating endothelial cell functions.

Inflammation, Nitro-Oxidative Stress, Impaired Autophagy, and Insulin Resistance as a Mechanistic Convergence Between Arterial Stiffness and Alzheimer's Disease

The average age of the world's elderly population is steadily increasing. This unprecedented rise in the aged world population will increase the prevalence of age-related disorders such as cardiovascular disease (CVD) and neurodegeneration. In recent years, there has been an increased interest in the potential interplay between CVDs and neurodegenerative syndromes, as several vascular risk factors have been associated with Alzheimer's disease (AD). Along these lines, arterial stiffness is an independent risk factor for both CVD and AD. In this review, we discuss several inflammaging-related disease mechanisms including acute tissue-specific inflammation, nitro-oxidative stress, impaired autophagy, and insulin resistance which may contribute to the proposed synergism between arterial stiffness and AD.