Atherosclerosis, Cardiovascular Disease, and COVID-19: A Narrative Review

Synergy Between NK Cells and Monocytes in Potentiating Cardiovascular Disease Risk in Severe COVID-19

BACKGROUND

Evidence suggests that COVID-19 predisposes to cardiovascular diseases (CVDs). While monocytes/macrophages play a central role in the immunopathogenesis of atherosclerosis, less is known about their immunopathogenic mechanisms that lead to CVDs during COVID-19. Natural killer (NK) cells, which play an intermediary role during pathologies like atherosclerosis, are dysregulated during COVID-19. Here, we sought to investigate altered immune cells and their associations with CVD risk during severe COVID-19.

METHODS

We measured plasma biomarkers of CVDs and determined phenotypes of circulating immune subsets using spectral flow cytometry. We compared these between patients with severe COVID-19 (severe, n=31), those who recovered from severe COVID-19 (recovered, n=29), and SARS-CoV-2-uninfected controls (controls, n=17). In vivo observations were supported using in vitro assays to highlight possible mechanistic links between dysregulated immune subsets and biomarkers during and after COVID-19. We performed multidimensional analyses of published single-cell transcriptome data of monocytes and NK cells during severe COVID-19 to substantiate in vivo findings.

RESULTS

During severe COVID-19, we observed alterations in cardiometabolic biomarkers including oxidized-low-density lipoprotein, which showed decreased levels in severe and recovered groups. Severe patients exhibited dysregulated monocyte subsets, including increased frequencies of proinflammatory intermediate monocytes (also observed in the recovered) and decreased nonclassical monocytes. All identified NK-cell subsets in the severe COVID-19 group displayed increased expression of activation and tissue-resident markers, such as CD69 (cluster of differentiation 69). We observed significant correlations between altered immune subsets and plasma oxidized-low-density lipoprotein levels. In vitro assays revealed increased uptake of oxidized-low-density lipoprotein into monocyte-derived macrophages in the presence of NK cells activated by plasma of patients with severe COVID-19. Transcriptome analyses confirmed enriched proinflammatory responses and lipid dysregulation associated with epigenetic modifications in monocytes and NK cells during severe COVID-19.

CONCLUSIONS

Our study provides new insights into the involvement of monocytes and NK cells in the increased CVD risk observed during and after COVID-19.

The Impact of Long COVID on the Quality of Life

Background and Objectives: The term long COVID refers to patients with a history of confirmed COVID-19 infection, who present symptoms that last for at least 2 months and cannot be explained by another diagnosis. Objectives: The present study aims to determine the most common symptoms of the long COVID syndrome and their impact on the quality of life. Materials and Methods: A prospective observational study was conducted on patients diagnosed with mild and moderate COVID-19 (based on a positive SARS-CoV-2 molecular diagnostic or rapid antigen test and severity form definition) at the Clinical Hospital of Infectious Diseases, Cluj-Napoca, Romania. Clinical examinations with detailed questions about symptoms were performed at the time of the diagnosis of COVID-19 and the six-month follow-up. Two years after COVID-19 infection, patients were invited to complete an online quality-of-life questionnaire regarding long COVID symptoms. Results: A total of 103 patients (35.92% males) with a mean age of 41.56 ± 11.77 were included in this study. Of the total number of patients, 65.04% presented mild forms of COVID-19. Data regarding the vaccination status showed that 83.5% were vaccinated against SARS-CoV-2. The most common symptoms at diagnosis were cough (80.6%), fatigue (80.4%), odynophagia (76.7%), and headaches (67.6%), with female patients being statistically more likely to experience it (p = 0.014). Patients with moderate forms of the disease had higher levels of both systolic (p = 0.008) and diastolic (p = 0.037) blood pressure at diagnosis, but no statistical difference was observed in the 6-month follow-up. The most common symptoms at 2 years (in 29 respondent subjects) were represented by asthenia (51.7%), headache (34.5%), memory disorders (27.6%), abdominal meteorism (27.6%), and arthralgia (27.6%). In terms of cardiovascular symptoms, fluctuating blood pressure values (20.7%), palpitations (17.2%), and increased heart rate values (17.2%) were recorded. Conclusions: If at the time of diagnosis, the most frequent manifestations of the disease were respiratory, together with headache and fatigue, at re-evaluation, asthenia, decreased effort tolerance, and neuropsychiatric symptoms prevailed. Regarding the cardiovascular changes as part of the long COVID clinical picture, some patients developed prehypertension, palpitations, and tachycardia.

Assessment of the Concentrations of Selected Aminothiols in Patients after COVID-19

Background: Data show that due to endothelial damage and thrombogenic effects, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection may accelerate the development of atherosclerosis and increase the risk of cardiovascular diseases (CVDs). The impaired metabolism of aminothiols increases oxidative stress, as these molecules are involved in antioxidant defense as well as in thiol redox control. In this study, total levels of selected aminothiols (i.e., cysteine (Cys), homocysteine (HCy), and glutathione) in convalescents after coronavirus disease of 2019 (COVID-19) were evaluated. The analyses were made according to the sex of the patients, time from COVID-19 onset, and COVID-19 severity. Methods: The study group consisted of 212 patients after COVID-19. Levels of total aminothiols were assessed in the blood plasma using high-performance liquid chromatography (HPLC). Results: The mean Cys concentrations were higher in men than in women (229.92 µmol/L ± 51.54 vs. 210.35 µmol/L ± 41.90, respectively; p = 0.003). Differences in Cys levels were also noticed in the total study group between patients distinguished due to time from disease onset (226.82 µmol/L ± 40.57 in <12 weeks, 232.23 µmol/L ± 47.99 in patients 12-24 weeks, and 208.08 µmol/L ± 48.43 in patients >24 weeks; p = 0.005). In addition, over 11% of total patients 12-24 weeks from disease onset had Cys levels above 300 µmol/L compared to almost 4% of patients <12 weeks and 2% of patients >24 weeks (p = 0.046). In sex-adjusted subgroups, significant differences due to time from COVID-19 were found in Cys levels in women (p = 0.004) and in glutathione levels in men (p = 0.024). None of the aminothiol levels differed between the subgroups based on the severity of COVID-19. Conclusions: Men had overall higher Cys levels than women. Cys levels were lower >24 weeks after COVID-19 onset than in the earlier period after disease onset. A partial elevation in Cys levels 12-24 weeks after the disease onset may contribute to the increase in CVD risk in the post-COVID-19 period.

Interactive effects of Composite Dietary Antioxidant Index with Body Mass Index for the risk of stroke among U.S. adults: insight from NHANES 2001-2018

Background

This cross-sectional study aims to explore the interactive effects of the Composite Dietary Antioxidant Index (CDAI) and Body Mass Index (BMI) on stroke risk among U.S. adults, utilizing data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2001 and 2018.

Methods

The analysis involved 42,042 participants from a representative sample of non-institutionalized U.S. civilians, selected through a stratified, multistage probability sampling method. Dietary intake data were collected over two 24-h periods using the Automated Multiple-Pass Method. The study calculated a modified CDAI to assess dietary antioxidant intake, excluding supplements and water sources. Statistical methods included multivariable logistic regression and Generalized Additive Models (GAM) to evaluate the interaction between CDAI scores and BMI in relation to stroke risk, adjusting for a wide range of demographic, lifestyle, and health covariates.

Results

The research identified a significant interaction between CDAI scores and BMI categories in stroke risk assessment. While a negative correlation was observed between CDAI scores and stroke risk across the total population (OR 0.97, 95% CI 0.96-0.99), this relationship varied notably across different BMI groups. In participants with a BMI ≥25, a statistically significant negative association persisted, displaying a non-linear pattern. The study also revealed an inflection point in the CDAI score, indicating a shift in the relationship between dietary antioxidants and stroke risk.

Conclusion

This study underscores the complex interaction between dietary antioxidant intake and BMI in determining stroke risk among U.S. adults. The findings suggest that individuals with higher BMI may experience more pronounced benefits from dietary antioxidants in stroke prevention. These insights could inform targeted dietary recommendations and public health strategies aimed at reducing stroke risk, particularly in populations with higher BMI. Further research is needed to fully understand these interactions and their implications for stroke prevention guidelines.

Natural products in atherosclerosis therapy by targeting PPARs: a review focusing on lipid metabolism and inflammation

Inflammation and dyslipidemia are critical inducing factors of atherosclerosis. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors and control the expression of multiple genes that are involved in lipid metabolism and inflammatory responses. However, synthesized PPAR agonists exhibit contrary therapeutic effects and various side effects in atherosclerosis therapy. Natural products are structural diversity and have a good safety. Recent studies find that natural herbs and compounds exhibit attractive therapeutic effects on atherosclerosis by alleviating hyperlipidemia and inflammation through modulation of PPARs. Importantly, the preparation of natural products generally causes significantly lower environmental pollution compared to that of synthesized chemical compounds. Therefore, it is interesting to discover novel PPAR modulator and develop alternative strategies for atherosclerosis therapy based on natural herbs and compounds. This article reviews recent findings, mainly from the year of 2020 to present, about the roles of natural herbs and compounds in regulation of PPARs and their therapeutic effects on atherosclerosis. This article provides alternative strategies and theoretical basis for atherosclerosis therapy using natural herbs and compounds by targeting PPARs, and offers valuable information for researchers that are interested in developing novel PPAR modulators.

Neurovascular coupling impairment as a mechanism for cognitive deficits in COVID-19

Components that comprise our brain parenchymal and cerebrovascular structures provide a homeostatic environment for proper neuronal function to ensure normal cognition. Cerebral insults (e.g. ischaemia, microbleeds and infection) alter cellular structures and physiologic processes within the neurovascular unit and contribute to cognitive dysfunction. COVID-19 has posed significant complications during acute and convalescent stages in multiple organ systems, including the brain. Cognitive impairment is a prevalent complication in COVID-19 patients, irrespective of severity of acute SARS-CoV-2 infection. Moreover, overwhelming evidence from in vitro, preclinical and clinical studies has reported SARS-CoV-2-induced pathologies in components of the neurovascular unit that are associated with cognitive impairment. Neurovascular unit disruption alters the neurovascular coupling response, a critical mechanism that regulates cerebromicrovascular blood flow to meet the energetic demands of locally active neurons. Normal cognitive processing is achieved through the neurovascular coupling response and involves the coordinated action of brain parenchymal cells (i.e. neurons and glia) and cerebrovascular cell types (i.e. endothelia, smooth muscle cells and pericytes). However, current work on COVID-19-induced cognitive impairment has yet to investigate disruption of neurovascular coupling as a causal factor. Hence, in this review, we aim to describe SARS-CoV-2's effects on the neurovascular unit and how they can impact neurovascular coupling and contribute to cognitive decline in acute and convalescent stages of the disease. Additionally, we explore potential therapeutic interventions to mitigate COVID-19-induced cognitive impairment. Given the great impact of cognitive impairment associated with COVID-19 on both individuals and public health, the necessity for a coordinated effort from fundamental scientific research to clinical application becomes imperative. This integrated endeavour is crucial for mitigating the cognitive deficits induced by COVID-19 and its subsequent burden in this especially vulnerable population.

Role of PCSK9 inhibition during the inflammatory stage of SARS-COV-2: an updated review

The potential role of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition in the management of COVID-19 and other medical conditions has emerged as an intriguing area of research. PCSK9 is primarily known for its impact on cholesterol metabolism, but recent studies have unveiled its involvement in various physiological processes, including inflammation, immune regulation, and thrombosis. In this abstract, the authors review the rationale and potential implications of PCSK9 inhibition during the inflammatory stage of SARS-CoV-2 infection. Severe cases of COVID-19 are characterized by an uncontrolled inflammatory response, often referred to as the cytokine storm, which can lead to widespread tissue damage and organ failure. Preclinical studies suggest that PCSK9 inhibition could dampen this inflammatory cascade by reducing the production of pro-inflammatory cytokines. Additionally, PCSK9 inhibition may protect against acute respiratory distress syndrome (ARDS) through its effects on lung injury and inflammation. COVID-19 has been linked to an increased risk of cardiovascular complications, especially in patients with pre-existing cardiovascular conditions or dyslipidemia. PCSK9 inhibitors are known for their ability to lower low-density lipoprotein (LDL) cholesterol levels by enhancing the recycling of LDL receptors in the liver. By reducing LDL cholesterol, PCSK9 inhibition might protect blood vessels from further damage and lower the risk of atherosclerotic plaque formation. Moreover, PCSK9 inhibitors have shown potential antithrombotic effects in preclinical studies, making them a potential avenue to mitigate the increased risk of coagulation disorders and thrombotic events observed in COVID-19. While the potential implications of PCSK9 inhibition are promising, safety considerations and possible risks need careful evaluation. Hypocholesterolemia, drug interactions, and long-term safety are some of the key concerns that should be addressed. Clinical trials are needed to establish the efficacy and safety of PCSK9 inhibitors in COVID-19 patients and to determine the optimal timing and dosing for treatment. Future research opportunities encompass investigating the immune response, evaluating long-term safety, exploring combination therapy possibilities, and advancing personalized medicine approaches. Collaborative efforts from researchers, clinicians, and policymakers are essential to fully harness the therapeutic potential of PCSK9 inhibition and translate these findings into meaningful clinical outcomes.

Synergistic Role of NK Cells and Monocytes in Promoting Atherogenesis in Severe COVID-19 Patients

Clinical data demonstrate an increased predisposition to cardiovascular disease (CVD) following severe COVID-19 infection. This may be driven by a dysregulated immune response associated with severe disease. Monocytes and vascular tissue resident macrophages play a critical role in atherosclerosis, the main pathology leading to ischemic CVD. Natural killer (NK) cells are a heterogenous group of cells that are critical during viral pathogenesis and are known to be dysregulated during severe COVID-19 infection. Their role in atherosclerotic cardiovascular disease has recently been described. However, the contribution of their altered phenotypes to atherogenesis following severe COVID-19 infection is unknown. We demonstrate for the first time that during and after severe COVID-19, circulating proinflammatory monocytes and activated NK cells act synergistically to increase uptake of oxidized low-density lipoprotein (Ox-LDL) into vascular tissue with subsequent foam cell generation leading to atherogenesis despite recovery from acute infection. Our data provide new insights, revealing the roles of monocytes/macrophages, and NK cells in COVID-19-related atherogenesis.

Molecular Linkage between Immune System Disorders and Atherosclerosis

A strong relationship exists between immune dysfunction and cardiovascular disease. Immune dysregulation can promote the development of cardiovascular diseases as well as exacerbate their course. The disorders may occur due to the presence of primary immune defects (currently known as inborn errors of immunity) and the more common secondary immune deficiencies. Secondary immune deficiencies can be caused by certain chronic conditions (such as diabetes, chronic kidney disease, obesity, autoimmune diseases, or cancer), nutritional deficiencies (including both lack of nutrients and bioactive non-nutrient compounds), and medical treatments and addictive substances. This article unravels the molecular linkage between the aforementioned immune system disorders and atherosclerosis.