PCSK9, A Promising Novel Target for Age-Related Cardiovascular Dysfunction

PCSK9 in Vascular Aging and Age-Related Diseases

The aging process significantly contributes to human disease, and as worldwide life expectancy increases, addressing the challenges of aging and age-related cardiovascular diseases is becoming increasingly urgent. Vascular aging is a key link between aging and the development of age-related diseases. Recent studies indicate that proprotein convertase subtilisin/kexin type 9 (PCSK9), a type of protein involved in the metabolism of lipids, is crucial in modulating vascular aging by affecting the physiological functioning of vascular cells. PCSK9 is linked to lipid metabolism and chronic inflammation and is involved in regulating senescence-related activities, including migration, proliferation, apoptosis, and differentiation. These factors contribute to the aging of vascular cells and age-related vascular diseases, including atherosclerosis, hypertension, coronary artery disease, and cerebrovascular diseases. Given its involvement in these processes, this article provides a comprehensive summary of PCSK9's regulatory functions in vascular aging, highlighting potential therapeutic targets for combating age-related cardiovascular diseases.

Exploring the Pleiotropy of PCSK9: A Wide Range of Influences from Lipid Regulation to Extrahepatic Function

In cardiovascular disease, the discovery of the proprotein convertase subtilisin/kexin type 9 (PCSK9) has undoubtedly opened a new chapter in regulating blood lipids. Since its first identification as a key regulator of low-density lipoprotein receptor (LDLR) degradation in 2003, the role of PCSK9 in cholesterol metabolism has been extensively studied. However, with further research, the pleiotropy of PCSK9 has gradually emerged, and its impact extends far beyond cholesterol metabolism in the liver. The purpose of this review is to systematically explore the pleiotropy of PCSK9, extending from its important role in lipid regulation to its extensive effects in extrahepatic tissues, and to reveal its potential role in cardiovascular health, nervous system function, and tumor biology. By integrating the latest research findings, this paper summarizes the complex mechanisms of action of PCSK9 in different biological processes and explores its potential and challenges as a therapeutic target.

Chronic alcohol consumption accelerates cardiovascular aging and decreases cardiovascular reserve capacity

The pathology of cardiovascular aging is complex, involving mitochondrial dysfunction, oxidative and nitrative stress, oxidative DNA injury, impaired lipid metabolism, cell death, senescence, and chronic inflammation. These processes lead to remodeling and structural changes in the cardiovascular system, resulting in a progressive decline in cardiovascular reserve capacity and health, and an increased risk of diseases and mortality. Excessive alcohol consumption exacerbates these risks by promoting hypertension, stroke, arrhythmias, coronary artery disease, cardiomyopathy, and sudden cardiac death, yet the effects of chronic alcohol consumption on cardiovascular aging remain unclear. Herein, we explored the impact of a 6-month 5% Lieber-DeCarli alcohol diet in young (3 months old) and aging (24-26 months old) Fisher F344BNF1 rats. We assessed detailed hemodynamics, mitochondrial function, oxidative/nitrative stress, lipid metabolism, inflammation, cell death, senescence, and myocardial fibrosis using the pressure-volume system, isolated vascular rings, and various histological, biochemical, and molecular biology methods. Alcohol consumption in both young and aging rats impaired mitochondrial function, disrupted cholesterol and triglyceride metabolism, and increased oxidative/nitrative stress, inflammation, cell death, and senescence, leading to a decline in systolic contractile function. In aging rats, alcohol further exacerbated diastolic dysfunction and myocardial fibrosis. Alcohol also increased oxidative/nitrative stress, apoptosis, and senescence in the vasculature, contributing to endothelial dysfunction and increased total peripheral resistance. Additionally, alcohol exacerbated the aging-related ventriculo-arterial uncoupling and diminished cardiac efficiency, further reducing cardiovascular reserve capacity. In conclusion, chronic alcohol consumption promotes cardiovascular aging and further diminishes the already impaired cardiac and vascular reserve capacity associated with aging.

PCSK9 Enhances Cardiac Fibrogenesis via the Activation of Toll-like Receptor and NLRP3 Inflammasome Signaling

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a novel target for reducing low-density lipoprotein cholesterol. PCSK9 activates the atherosclerosis process through pro-inflammation signaling. Furthermore, the serum level of PCSK9 is positively correlated with mortality in patients with heart failure (HF). Cardiac fibrosis plays a crucial role in the pathophysiology of HF. In this study, we intended to examine whether PCSK9 can increase fibroblast activities and explore what its underlying mechanisms are. Migration, proliferation analyses, and Western blotting were used on human cardiac fibroblasts with and without PCSK9. Alirocumab (a PCSK9 inhibitor, 10 mg/kg/week intra-peritoneally for 28 consecutive days) was treated in isoproterenol (100 mg/kg, subcutaneous injection)-induced HF rats. PCSK9 (50, 100 ng/mL) increased proliferation, myofibroblast differentiation capability, and collagen type I production. Compared with control cells, PCSK9 (100 ng/mL)-treated cardiac fibroblasts showed higher nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3), interleukin (IL)-1, myofibroblast differentiation, and collagen production capabilities, which were attenuated by MCC950 (an NLRP3 inhibitor, 100 μmol/L). PCSK9 upregulated Myd88 and NF-κB signaling, which were reduced by TAK242 (a toll-like receptor (TLR) 4 inhibitor, 10 μmol/L). Moreover, alirocumab significantly improved left ventricular systolic function and attenuated fibrosis in HF rats. In conclusion, PCSK9 upregulates NLRP3 signaling and the profibrotic activities of cardiac fibroblasts through the activation of TLR4/Myd88/NF-κB signaling.

The functions of apolipoproteins and lipoproteins in health and disease

Lipoproteins and apolipoproteins are crucial in lipid metabolism, functioning as essential mediators in the transport of cholesterol and triglycerides and being closely related to the pathogenesis of multiple systems, including cardiovascular. Lipoproteins a (Lp(a)), as a unique subclass of lipoproteins, is a low-density lipoprotein(LDL)-like particle with pro-atherosclerotic and pro-inflammatory properties, displaying high heritability. More and more strong evidence points to a possible link between high amounts of Lp(a) and cardiac conditions like atherosclerotic cardiovascular disease (ASCVD) and aortic stenosis (AS), making it a risk factor for heart diseases. In recent years, Lp(a)'s role in other diseases, including neurological disorders and cancer, has been increasingly recognized. Although therapies aimed at low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) have achieved significant success, elevated Lp(a) levels remain a significant clinical management problem. Despite the limited efficacy of current lipid-lowering therapies, major clinical advances in new Lp(a)-lowering therapies have significantly advanced the field. This review, grounded in the pathophysiology of lipoproteins, seeks to summarize the wide-ranging connections between lipoproteins (such as LDL-C and HDL-C) and various diseases, alongside the latest clinical developments, special emphasis is placed on the pivotal role of Lp(a) in cardiovascular disease, while also examining its future potential and mechanisms in other conditions. Furthermore, this review discusses Lp(a)-lowering therapies and highlights significant recent advances in emerging treatments, advocates for further exploration into Lp(a)'s pathogenic mechanisms and its potential as a therapeutic target, proposing new secondary prevention strategies for high-risk individuals.

Sex differences in pathogenesis and treatment of dyslipidemia in patients with type 2 diabetes and steatotic liver disease

Previously published studies have shown that women with type 2 diabetes have a higher risk of atherosclerotic cardiovascular disease than men with type 2 diabetes. The exact reason for this is not yet known. The association between metabolic dysfunction-associated steatotic liver disease and type 2 diabetes appears to be bidirectional, meaning that the onset of one may increase the risk of the onset and progression of the other. Dyslipidemia is common in both diseases. Our aim was therefore to investigate whether there is a sex difference in the pathogenesis and management of dyslipidemia in patients with type 2 diabetes and steatotic liver disease with metabolic dysfunction. While the majority of published studies to date have found no difference between men and women in statin treatment, some studies have shown reduced effectiveness in women compared to men. Statin treatment is under-prescribed for both type 2 diabetics and patients with dysfunction-associated steatotic liver disease. No sex differences were found for ezetimibe treatment. However, to the best of our knowledge, no such study was found for fibrate treatment. Conflicting results on the efficacy of newer cholesterol-lowering PCSK9 inhibitors have been reported in women and men. Results from two real-world studies suggest that up-titration of statin dose improves the efficacy of PCSK9 inhibitors in women. Bempedoic acid treatment has been shown to be effective and safe in patients with type 2 diabetes and more effective in lipid lowering in women compared to men, based on phase 3 results published to date. Further research is needed to clarify whether the sex difference in dyslipidemia management shown in some studies plays a role in the risk of ASCVD in patients with type 2 diabetes and steatotic liver disease with metabolic dysfunction.

Targeting Oxidative Stress in Neurodegenerative Disorders: A Novel Role for PCSK9 Inhibition?

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein that regulates cholesterol levels by lysosomal low-density lipoprotein receptor (LDLR) degradation and has recently been associated with the production of neuronal oxidative stress and age-associated cardiovascular dysfunction. Since increased oxidative stress and vascular dysfunction are implicated in the pathology of aging and various neurodegenerative disorders, targeting PCSK9 may offer a promising therapeutic avenue for addressing these conditions. While the precise mechanisms through which PCSK9 contributes to vascular and neuronal oxidative stress in the brain remain elusive, preclinical studies have highlighted a neuroprotective effect linked to PCSK9 inhibition. This inhibition has shown promise in reducing oxidative stress, mitigating neuroinflammation, and alleviating neuropathological changes, thus underscoring the therapeutic potential of this approach in addressing neurodegenerative conditions.

Construction and Validation of a Predictive Model for Coronary Artery Disease Using Extreme Gradient Boosting

Purpose

Early recognition of coronary artery disease (CAD) could delay its progress and significantly reduce mortality. Sensitive, specific, cost-efficient and non-invasive indicators for assessing individual CAD risk in community population screening are urgently needed.

Patients and Methods

3112 patients with CAD and 3182 controls were recruited from three clinical centers in China, and differences in baseline and clinical characteristics were compared. For the discovery cohort, the least absolute shrinkage and selection operator (LASSO) regression was used to identify significant features and four machine learning algorithms (logistic regression, support vector machine (SVM), random forest (RF) and extreme gradient boosting (XGBoost)) were applied to construct models for CAD risk assessment, the receiver operating characteristics (ROC) curve and precision-recall (PR) curve were conducted to evaluate their predictive accuracy. The optimal model was interpreted by Shapley additive explanations (SHAP) analysis and assessed by the ROC curve, calibration curve, and decision curve analysis (DCA) and validated by two external cohorts.

Results

Using LASSO filtration, all included variables were considered to be statistically significant. Four machine learning models were constructed based on these features and the results of ROC and PR curve implied that the XGBoost model exhibited the highest predictive performance, which yielded a high area of ROC curve (AUC) of 0.988 (95% CI: 0.986-0.991) to distinguish CAD patients from controls with a sensitivity of 94.6% and a specificity of 94.6%. The calibration curve showed that the predicted results were in good agreement with actual observations, and DCA exhibited a better net benefit across a wide range of threshold probabilities. External validation of the model also exhibited favorable discriminatory performance, with an AUC, sensitivity, and specificity of 0.953 (95% CI: 0.945-0.960), 89.9%, and 87.1% in the validation cohort, and 0.935 (95% CI: 0.915-0.955), 82.0%, and 90.3% in the replication cohort.

Conclusion

Our model is highly informative for clinical practice and will be conducive to primary prevention and tailoring the precise management for CAD patients.

Pharmacotherapy for Coronary Artery Disease and Acute Coronary Syndrome in the Aging Population

PURPOSE OF REVIEW

To provide a comprehensive summary of relevant studies and evidence concerning the utilization of different pharmacotherapeutic and revascularization strategies in managing coronary artery disease and acute coronary syndrome specifically in the older adult population.

RECENT FINDINGS

Approximately 30% to 40% of hospitalized patients with acute coronary syndrome are older adults, among whom the majority of cardiovascular-related deaths occur. When compared to younger patients, these individuals generally experience inferior clinical outcomes. Most clinical trials assessing the efficacy and safety of various therapeutics have primarily enrolled patients under the age of 75, in addition to excluding those with geriatric complexities. In this review, we emphasize the need for a personalized and comprehensive approach to pharmacotherapy for coronary heart disease and acute coronary syndrome in older adults, considering concomitant geriatric syndromes and age-related factors to optimize treatment outcomes while minimizing potential risks and complications. In the realm of clinical practice, cardiovascular and geriatric risks are closely intertwined, with both being significant factors in determining treatments aimed at reducing negative outcomes and attaining health conditions most valued by older adults.

PCSK9 inhibition attenuates alcohol-associated neuronal oxidative stress and cellular injury

Alcohol Use Disorder (AUD) is a persistent condition linked to neuroinflammation, neuronal oxidative stress, and neurodegenerative processes. While the inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) has demonstrated effectiveness in reducing liver inflammation associated with alcohol, its impact on the brain remains largely unexplored. This study aimed to assess the effects of alirocumab, a monoclonal antibody targeting PCSK9 to lower systemic low-density lipoprotein cholesterol (LDL-C), on central nervous system (CNS) pathology in a rat model of chronic alcohol exposure. Alirocumab (50 mg/kg) or vehicle was administered weekly for six weeks in 32 male rats subjected to a 35 % ethanol liquid diet or a control liquid diet (n = 8 per group). The study evaluated PCSK9 expression, LDL receptor (LDLR) expression, oxidative stress, and neuroinflammatory markers in brain tissues. Chronic ethanol exposure increased PCSK9 expression in the brain, while alirocumab treatment significantly upregulated neuronal LDLR and reduced oxidative stress in neurons and brain vasculature (3-NT, p22phox). Alirocumab also mitigated ethanol-induced microglia recruitment in the cortex and hippocampus (Iba1). Additionally, alirocumab decreased the expression of pro-inflammatory cytokines and chemokines (TNF, CCL2, CXCL3) in whole brain tissue and attenuated the upregulation of adhesion molecules in brain vasculature (ICAM1, VCAM1, eSelectin). This study presents novel evidence that alirocumab diminishes oxidative stress and modifies neuroimmune interactions in the brain elicited by chronic ethanol exposure. Further investigation is needed to elucidate the mechanisms by which PCSK9 signaling influences the brain in the context of chronic ethanol exposure.

PCSK9: an emerging player in cardiometabolic aging and its potential as a therapeutic target and biomarker

Proprotein convertase subtilisin/kexin type 9 (PCSK9), renowned for its pivotal role in low-density lipoprotein (LDL) regulation, has emerged as a compelling regulator of cardiometabolic aging. Beyond its well-established involvement in cholesterol metabolism, PCSK9's multifaceted influence on the aging processes of the cardiovascular and metabolic systems is garnering increasing attention. This review delves into the evolving landscape of PCSK9 in the context of cardiometabolic aging, offering fresh insights into its potential implications. Drawing inspiration from pioneering research conducted by the Pacher laboratory (Arif et al., Geroscience, 2023, PMID: 37726433), we delve into the intricate interplay of PCSK9 within the aging heart and liver, shedding light on its newfound significance. Recent studies underscore PCSK9's pivotal role in liver aging, suggesting intriguing connections between hepatic aging, lipid metabolism, and cardiovascular health. Additionally, we explore the therapeutic potential of PCSK9 as both a target and a biomarker, within the context of age-related cardiovascular disease.

Data-driven transcriptomics analysis identifies PCSK9 as a novel key regulator in liver aging

The liver, as a crucial metabolic organ, undergoes significant pathological changes during the aging process, which can have a profound impact on overall health. To gain a comprehensive understanding of these alterations, we employed data-driven approaches, along with biochemical methods, histology, and immunohistochemistry techniques, to systematically investigate the effects of aging on the liver. Our study utilized a well-established rat aging model provided by the National Institute of Aging. Systems biology approaches were used to analyze genome-wide transcriptomics data from liver samples obtained from young (4-5 months old) and aging (20-21 months old) Fischer 344 rats. Our findings revealed pathological changes occurring in various essential biological processes in aging livers. These included mitochondrial dysfunction, increased oxidative/nitrative stress, decreased NAD + content, impaired amino acid and protein synthesis, heightened inflammation, disrupted lipid metabolism, enhanced apoptosis, senescence, and fibrosis. These results were validated using independent datasets from both human and rat aging studies. Furthermore, by employing co-expression network analysis, we identified novel driver genes responsible for liver aging, confirmed our findings in human aging subjects, and pointed out the cellular localization of the driver genes using single-cell RNA-sequencing human data. Our study led to the discovery and validation of a liver-specific gene, proprotein convertase subtilisin/kexin type 9 (PCSK9), as a potential therapeutic target for mitigating the pathological processes associated with aging in the liver. This finding envisions new possibilities for developing interventions aimed to improve liver health during the aging process.