Understanding the heart-brain axis response in COVID-19 patients: A suggestive perspective for therapeutic development

Cognitive Impairment and Synaptic Dysfunction in Cardiovascular Disorders: The New Frontiers of the Heart-Brain Axis

Within the central nervous system, synaptic plasticity, fundamental to processes like learning and memory, is largely driven by activity-dependent changes in synaptic strength. This plasticity often manifests as long-term potentiation (LTP) and long-term depression (LTD), which are bidirectional modulations of synaptic efficacy. Strong epidemiological and experimental evidence show that the heart-brain axis could be severely compromised by both neurological and cardiovascular disorders. Particularly, cardiovascular disorders, such as heart failure, hypertension, obesity, diabetes and insulin resistance, and arrhythmias, may lead to cognitive impairment, a condition known as cardiogenic dementia. Herein, we review the available knowledge on the synaptic and molecular mechanisms by which cardiogenic dementia may arise and describe how LTP and/or LTD induction and maintenance may be compromised in the CA1 region of the hippocampus by heart failure, metabolic syndrome, and arrhythmias. We also discuss the emerging evidence that endothelial dysfunction may contribute to directly altering hippocampal LTP by impairing the synaptically induced activation of the endothelial nitric oxide synthase. A better understanding of how CV disorders impact on the proper function of central synapses will shed novel light on the molecular underpinnings of cardiogenic dementia, thereby providing a new perspective for more specific pharmacological treatments.

Impact of healthcare system strain on the implementation of ICU sedation practices and encephalopathy burden during the early COVID-19 pandemic

The COVID-19 pandemic posed unprecedented challenges to healthcare systems worldwide, particularly in managing critically ill patients requiring mechanical ventilation early in the pandemic. Surging patient volumes strained hospital resources and complicated the implementation of standard-of-care intensive care unit (ICU) practices, including sedation management. The objective of this study was to evaluate the impact of an evidence-based ICU sedation bundle during the early COVID-19 pandemic. The bundle was designed by a multi-disciplinary collaborative to reinforce best clinical practices related to ICU sedation. The bundle was implemented prospectively with retrospective analysis of electronic medical record data. The setting was the ICUs of a single-center tertiary hospital. The patients were the ICU patients requiring mechanical ventilation for confirmed COVID-19 between March and June 2020. A learning health collaborative developed a sedation bundle encouraging goal-directed sedation and use of adjunctive strategies to avoid excessive sedative administration. Implementation strategies included structured in-service training, audit and feedback, and continuous improvement. Sedative utilization and clinical outcomes were compared between patients admitted before and after the sedation bundle implementation. Quasi-experimental interrupted time-series analyses of pre and post intervention sedative utilization, hospital length of stay, and number of days free of delirium, coma, or death in 21 days (as a quantitative measure of encephalopathy burden). The analysis used the time duration between start of the COVID-19 wave and ICU admission to identify a "breakpoint" indicating a change in observed trends. A total of 183 patients (age 59.0 ± 15.9 years) were included, with 83 (45%) admitted before the intervention began. Benzodiazepine utilization increased for patients admitted after the bundle implementation, while agents intended to reduce benzodiazepine use showed no greater utilization. No "breakpoint" was identified to suggest the bundle impacted any endpoint measure. However, increasing time between COVID-19 wave start and ICU admission was associated with fewer delirium, coma, and death-free days (β =  - 0.044 [95% CI - 0.085, - 0.003] days/wave day); more days of benzodiazepine infusion (β = 0.056 [95% CI 0.025, 0.088] days/wave day); and a higher maximum benzodiazepine infusion rate (β = 0.079 [95% CI 0.037, 0.120] mg/h/wave day). The evidence-based practice bundle did not significantly alter sedation utilization patterns during the first COVID-19 wave. Sedation practices deteriorated and encephalopathy burden increased over time, highlighting that strategies to reinforce clinical practices may be hindered under conditions of extreme healthcare system strain.

Comparative analysis of health status and health service utilization patterns among rural and urban elderly populations in Hungary: a study on the challenges of unhealthy aging

The demographic transition poses a significant challenge for health systems, especially in Central and Eastern European (CEE) countries, where the healthcare needs of aging populations are on the rise. This study aimed to describe and compare the health status and utilization of health services among the elderly residing in urban and rural areas of the most deprived region in Hungary. A comprehensive health survey was conducted in 2022, involving a randomly selected sample of 443 older adults (≥ 65 years) in Northeast Hungary. Multivariable logistic regression models adjusting for age, sex, education, financial status, chronic diseases, and activity limitations were used to investigate the association between type of residence and health service use. Among the study participants, 62.3% were female, 38.3% attained primary education, 12.5% reported a bad or very bad financial situation and 52.6% lived in urban areas. Overall, 24% of the elderly rated their health as very good or good (27.8% in urban and 19.7% in rural areas), while 57.8% (52.6% and 63.5% in urban and rural areas) reported limitations in daily activities. Compared to urban residents, rural residents reported lower rates of dentist visits (p = 0.006), specialist visits (p = 0.028), faecal occult blood testing (p < 0.001), colorectal cancer screening with colonoscopy (p = 0.014), and breast cancer screening (p = 0.035), and a higher rate of blood pressure measurement (p = 0.042). Multivariable models indicated that urban residence was positively associated with faecal occult blood testing (OR = 2.32, p = 0.014), but negatively associated with blood pressure (OR = 0.42, p = 0.017) and blood glucose measurements (OR = 0.48, p = 0.009). These findings highlight the influence of residence on health service utilization among older adults in Hungary. Further comprehensive studies are needed to better understand the health needs of the elderly population and to develop policies aimed at promoting healthy aging in CEE countries.

The interplay between Sars-Cov-2 infection related cardiovascular diseases and depression. Common mechanisms, shared symptoms

In 2020 the World Health organization announced a pandemic due to the outbreak of the Coronavirus disease 19. Pneumonia was the most common manifestation of the Sars-Cov-2 infection, however, clinical papers describe Sars-Cov-2 associated cardiovascular pathologies, such as ACS, myopericarditis, cardiomyopathies, dysrhythmias, as leading causes of increased morbidity and mortality. The short and long term prognosis of Sars-Cov-2-related cardiovascular diseases was defined not only by the disease severity itself but also by associated conditions and complications, among which mental health issues (stress, depression and anxiety) have a negative impact. The interplay between Sars-Cov-2 infection, cardiovascular disease and depression may be explained by hyperinflammation, unhealthy lifestyle and inter-organ communication, mediated by extracellular vesicles (EV) and non-coding MicroRNA (miRNA). The long Covid syndrome is characterized with orthostatic hypotension, impaired cardiac and cerebral perfusion, postural orthostatic tachycardia syndrome (POTS), syncope, chest pain, dyspnea, palpitation, chronic fatigue syndrome, 'brain fog', memory, cognitive and sleep difficulties, depression and anxiety. From a clinical point of view these symptoms may be considered as common symptoms representing not only a cardiac but also a neurological/psychiatric problem. Consequently assessment of these symptoms are of paramount importance. Due to their complexity, management of these patients requires multidisciplinary care.

Landscape of molecular crosstalk between SARS-CoV-2 infection and cardiovascular diseases: emphasis on mitochondrial dysfunction and immune-inflammation

BACKGROUND

SARS-CoV-2, the pathogen of COVID-19, is a worldwide threat to human health and causes a long-term burden on the cardiovascular system. Individuals with pre-existing cardiovascular diseases are at higher risk for SARS-CoV-2 infection and tend to have a worse prognosis. However, the relevance and pathogenic mechanisms between COVID-19 and cardiovascular diseases are not yet completely comprehended.

METHODS

Common differentially expressed genes (DEGs) were obtained in datasets of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) infected with SARS-CoV-2 and myocardial tissues from heart failure patients. Further GO and KEGG pathway analysis, protein-protein interaction (PPI) network construction, hub genes identification, immune microenvironment analysis, and drug candidate predication were performed. Then, an isoproterenol-stimulated myocardial hypertrophy cell model and a transverse aortic constriction-induced mouse heart failure model were employed to validate the expression of hub genes.

RESULTS

A total of 315 up-regulated and 78 down-regulated common DEGs were identified. Functional enrichment analysis revealed mitochondrial metabolic disorders and extensive immune inflammation as the most prominent shared features of COVID-19 and cardiovascular diseases. Then, hub DEGs, as well as hub immune-related and mitochondria-related DEGs, were screened. Additionally, nine potential therapeutic agents for COVID-19-related cardiovascular diseases were proposed. Furthermore, the expression patterns of most of the hub genes related to cardiovascular diseases in the validation dataset along with cellular and mouse myocardial damage models, were consistent with the findings of bioinformatics analysis.

CONCLUSIONS

The study unveiled the molecular networks and signaling pathways connecting COVID-19 and cardiovascular diseases, which may provide novel targets for intervention of COVID-19-related cardiovascular diseases.

Mitochondrial dysfunction at the crossroad of cardiovascular diseases and cancer

A large body of evidence indicates the existence of a complex pathophysiological relationship between cardiovascular diseases and cancer. Mitochondria are crucial organelles whose optimal activity is determined by quality control systems, which regulate critical cellular events, ranging from intermediary metabolism and calcium signaling to mitochondrial dynamics, cell death and mitophagy. Emerging data indicate that impaired mitochondrial quality control drives myocardial dysfunction occurring in several heart diseases, including cardiac hypertrophy, myocardial infarction, ischaemia/reperfusion damage and metabolic cardiomyopathies. On the other hand, diverse human cancers also dysregulate mitochondrial quality control to promote their initiation and progression, suggesting that modulating mitochondrial homeostasis may represent a promising therapeutic strategy both in cardiology and oncology. In this review, first we briefly introduce the physiological mechanisms underlying the mitochondrial quality control system, and then summarize the current understanding about the impact of dysregulated mitochondrial functions in cardiovascular diseases and cancer. We also discuss key mitochondrial mechanisms underlying the increased risk of cardiovascular complications secondary to the main current anticancer strategies, highlighting the potential of strategies aimed at alleviating mitochondrial impairment-related cardiac dysfunction and tumorigenesis. It is hoped that this summary can provide novel insights into precision medicine approaches to reduce cardiovascular and cancer morbidities and mortalities.

Gene silencing of endothelial von Willebrand factor reduces the susceptibility of human endothelial cells to SARS-CoV-2 infection

Mechanisms underlying vascular endothelial susceptibility to infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are not fully understood. Emerging evidence indicates that patients lacking von Willebrand factor (vWF), an endothelial hallmark, are less severely affected by SARS-CoV-2 infection, yet the precise role of endothelial vWF in modulating coronavirus entry into endothelial cells is unknown. In the present study, we demonstrated that effective gene silencing by short interfering RNA (siRNA) for vWF expression in resting human umbilical vein endothelial cells (HUVECs) significantly reduced by 56% the cellular levels of SARS-CoV-2 genomic RNA. Similar reduction in intracellular SARS-CoV-2 genomic RNA levels was observed in non-activated HUVECs treated with siRNA targeting angiotensin-converting enzyme 2 (ACE2), the cellular gateway to coronavirus. By integrating quantitative information from real-time PCR and high-resolution confocal imaging, we demonstrated that ACE2 gene expression and its plasma membrane localization in HUVECs were both markedly reduced after treatment with siRNA anti-vWF or anti-ACE2. Conversely, siRNA anti-ACE2 did not reduce endothelial vWF gene expression and protein levels. Finally, SARS-CoV-2 infection of viable HUVECs was enhanced by overexpression of vWF, which increased ACE2 levels. Of note, we found a similar increase in interferon-β mRNA levels following transfection with untargeted, anti-vWF or anti-ACE2 siRNA and pcDNA3.1-WT-VWF. We envision that siRNA targeting endothelial vWF will protect against productive endothelial infection by SARS-CoV-2 through downregulation of ACE2 expression and might serve as a novel tool to induce disease resistance by modulating the regulatory role of vWF on ACE2 expression.

A critical review on brain and heart axis response in COVID-19 patients: Molecular mechanisms, mediators, biomarkers, and therapeutics

Since the outbreak of highly virulent coronaviruses, significant interest was assessed to the brain and heart axis (BHA) in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-affected patients. The majority of clinical reports accounted for unusual symptoms associated with SARS-CoV-2 infections which are of the neurological type, such as headache, nausea, dysgeusia, anosmia, and cerebral infarction. The SARS-CoV-2 enters the cells through the angiotensin-converting enzyme (ACE-2) receptor. Patients with prior cardiovascular disease (CVD) have a higher risk of COVID-19 infection and it has related to various cardiovascular (CV) complications. Infected patients with pre-existing CVDs are also particularly exposed to critical health outcomes. Overall, COVID-19 affected patients admitted to intensive care units (ICU) and exposed to stressful environmental constraints, featured with a cluster of neurological and CV complications. In this review, we summarized the main contributions in the literature on how SARS-CoV-2 could interfere with the BHA and its role in affecting multiorgan disorders. Specifically, the central nervous system involvement, mainly in relation to CV alterations in COVID-19-affected patients, is considered. This review also emphasizes the biomarkers and therapy options for COVID-19 patients presenting with CV problems.

Post-acute sequelae of COVID-19: understanding and addressing the burden of multisystem manifestations

Individuals with SARS-CoV-2 infection can develop symptoms that persist well beyond the acute phase of COVID-19 or emerge after the acute phase, lasting for weeks or months after the initial acute illness. The post-acute sequelae of COVID-19, which include physical, cognitive, and mental health impairments, are known collectively as long COVID or post-COVID-19 condition. The substantial burden of this multisystem condition is felt at individual, health-care system, and socioeconomic levels, on an unprecedented scale. Survivors of COVID-19-related critical illness are at risk of the well known sequelae of acute respiratory distress syndrome, sepsis, and chronic critical illness, and these multidimensional morbidities might be difficult to differentiate from the specific effects of SARS-CoV-2 and COVID-19. We provide an overview of the manifestations of post-COVID-19 condition after critical illness in adults. We explore the effects on various organ systems, describe potential pathophysiological mechanisms, and consider the challenges of providing clinical care and support for survivors of critical illness with multisystem manifestations. Research is needed to reduce the incidence of post-acute sequelae of COVID-19-related critical illness and to optimise therapeutic and rehabilitative care and support for patients.

Association of COVID-19 with Comorbidities: An Update

Coronavirus disease (COVID-19) is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) which was identified in Wuhan, China in December 2019 and jeopardized human lives. It spreads at an unprecedented rate worldwide, with serious and still-unfolding health conditions and economic ramifications. Based on the clinical investigations, the severity of COVID-19 appears to be highly variable, ranging from mild to severe infections including the death of an infected individual. To add to this, patients with comorbid conditions such as age or concomitant illnesses are significant predictors of the disease's severity and progression. SARS-CoV-2 enters inside the host cells through ACE2 (angiotensin converting enzyme2) receptor expression; therefore, comorbidities associated with higher ACE2 expression may enhance the virus entry and the severity of COVID-19 infection. It has already been recognized that age-related comorbidities such as Parkinson's disease, cancer, diabetes, and cardiovascular diseases may lead to life-threatening illnesses in COVID-19-infected patients. COVID-19 infection results in the excessive release of cytokines, called "cytokine storm", which causes the worsening of comorbid disease conditions. Different mechanisms of COVID-19 infections leading to intensive care unit (ICU) admissions or deaths have been hypothesized. This review provides insights into the relationship between various comorbidities and COVID-19 infection. We further discuss the potential pathophysiological correlation between COVID-19 disease and comorbidities with the medical interventions for comorbid patients. Toward the end, different therapeutic options have been discussed for COVID-19-infected comorbid patients.

INTRACARDIAC HEMODYNAMICS, CEREBRAL BLOOD FLOW AND MICROEMBOLIC SIGNAL BURDEN IN STABLE CORONARY ARTERY DISEASE PATIENTS WITH CONCOMITANT COVID-19

OBJECTIVE

The aim: To estimate the changes in intracardiac hemodynamics, cerebral blood flow (CBF), and microembolic signals` (MES) burden in stable coronary artery disease (SCAD) patients with concomitant COVID-19.

PATIENTS AND METHODS

Materials and methods: The cross-sectional study analyzed the data from 80 patients, being subdivided as follows: group 1 (G1) - SCAD without COVID-19 (n=30); group 2 (G2) - SCAD with concomitant COVID-19 (n=25); group 3 (G3) - COVID-19 without SCAD (n=25). The control group (CG) included 30 relatively healthy volunteers. CBF and total MES count were assessed by transcranial Doppler ultrasound.

RESULTS

Results: Transthoracic echocardiography data from G2 revealed the most pronounced left ventricular (LV) dilation and its contractility decline (the rise of end-systolic volume (ESV) and ejection fraction decrease), as compared to G1 and G3. G1-G3 patients (vs. CG) presented with lower peak systolic velocities in all the studied intracranial arteries (middle and posterior cerebral arteries bilaterally, and basilar artery), along with the higher MES count. Such a drop in CBF was the most pronounced in G2. Both G2 and G3 demonstrated the highest amount of MES, with slightly higher count in G2. We built a linear neural network, discriminating the pattern of both higher LV ESV and MES count, being inherent to G2.

CONCLUSION

Conclusions: G2 patients demonstrated the LV dilation and its systolic function impairment, and presented with CBF drop and MES burden increase, being more advanced in contrast to G1 and G3. LV contractility decrease was associated with the higher MES load in the case of SCAD and COVID-19 constellation.

Common Biomarkers Associated with Delirium in Hospitalized Patients with COVID-19 at the Epicentre of Turkish Coronavirus Outbreak: A Case-Control Study

Introduction

To investigate the differences in biochemical characteristics between Coronavirus Disease 2019 (COVID-19) patients with and without delirium in non-intensive care (IC) COVID-19 units was aimed.

Methods

This study was designed as an observational, single-centered, and case-control study consisting of 43 delirious patients and matched 45 non-delirious patients admitted to non-IC COVID-19 units. Delirium was diagnosed by a consultant psychiatrist according to the DSM-5 delirium diagnostic criteria. Independent variables such as laboratory tests at the time of admission, clinical features, and patient characteristics were obtained from electronic medical records by researchers. In the primary analyses, binomial logistic regression models were used to investigate the factors associated with delirium, which was identified as the outcome variable. Multivariate logistic models were then adjusted for potential confounding factors, including age, gender, history of neurocognitive disorders and Charlson Comorbidity Index (CCI).

Results

We observed higher levels of urea, d-dimer, troponin-T, proB-type natriuretic peptide, and CCI in patients with delirium compared to patients without delirium. We also observed lower levels of estimated glomerular filtration rate (eGFR), serum albumin, and O₂ saturation and a decrease in the length of stay at the hospital. After adjusting for confounding factors such as gender, age, and comorbidity, we found that urea (adjusted estimate=0.015; 95% Confidence Interval [CI]=0.058-0.032, P=0.039), urea/creatinine ratio (adjusted estimate=0.008; 95% CI=0.002-0.013, P=0.011), and troponin-T (adjusted estimate=0.066; 95% CI=0.014-0.118, P=0.014) were independent biomarkers associated with delirium.

Conclusion

Delirium is associated with higher urea levels and urea/creatinine ratios in COVID-19 patients. In addition, the relationship between troponin-T and delirium may help understand the potential link between the brain and the heart in COVID-19. Additional multi-centred studies with larger sample sizes are needed to generalise these results.

Different patterns of excess all-cause mortality by age and sex in Hungary during the 2nd and 3rd waves of the COVID-19 pandemic

It is well accepted that COVID-19-related mortality shows a strong age dependency. However, temporal changes in the age distribution of excess relative mortality between waves of the pandemic are less frequently investigated. We aimed to assess excess absolute mortality and the age-distribution of all-cause mortality during the second and third waves of the COVID-19 pandemic in Hungary compared to the same periods of non-pandemic years. Rate ratios for excess all-cause mortality with 95% confidence intervals and the number of excess deaths for the second (week 41 of 2020 through week 4 of 2021) and third waves (weeks 7-21 of 2021) of the COVID pandemic for the whole of Hungary compared to the same periods of the pre-pandemic years were estimated for 10-year age strata using Poisson regression. Altogether, 9771 (95% CI: 9554-9988) excess deaths were recorded during the second wave of the pandemic, while it was lower, 8143 (95% CI: 7953-8333) during the third wave. During the second wave, relative mortality peaked for ages 65-74 and 75-84 (RR 1.37, 95%CI 1.33-1.41, RR 1.38, 95%CI 1.34-1.42). Conversely, during the third wave, relative mortality peaked for ages 35-44 (RR 1.43, 95%CI 1.33-1.55), while those ≥65 had substantially lower relative risks compared to the second wave. The reduced relative mortality among the elderly during the third wave is likely a consequence of the rapidly increasing vaccination coverage of the elderly coinciding with the third wave. The hugely increased relative mortality of those 35-44 could point to non-biological causes, such as less stringent adherence to non-pharmaceutical measures in this population.

Tissue repair strategies: What we have learned from COVID-19 in the application of MSCs therapy

Coronavirus disease 2019 (COVID-19) infection evokes severe proinflammatory storm and pulmonary infection with the number of confirmed cases (more than 200 million) and mortality (5 million) continue to surge globally. A number of vaccines (e.g., Moderna, Pfizer, Johnson/Janssen and AstraZeneca vaccines) have been developed over the past two years to restrain the rapid spread of COVID-19. However, without much of effective drug therapies, COVID-19 continues to cause multiple irreversible organ injuries and is drawing intensive attention for cell therapy in the management of organ damage in this devastating COVID-19 pandemic. For example, mesenchymal stem cells (MSCs) have exhibited promising results in COVID-19 patients. Preclinical and clinical findings have favored the utility of stem cells in the management of COVID-19-induced adverse outcomes via inhibition of cytokine storm and hyperinflammatory syndrome with coinstantaneous tissue regeneration capacity. In this review, we will discuss the existing data with regards to application of stem cells for COVID-19.

Risk stratification of patients with SARS-CoV-2 by tissue factor expression in circulating extracellular vesicles

Inflammatory response following SARS-CoV-2 infection results in substantial increase of amounts of intravascular pro-coagulant extracellular vesicles (EVs) expressing tissue factor (CD142) on their surface. CD142-EV turned out to be useful as diagnostic biomarker in COVID-19 patients. Here we aimed at studying the prognostic capacity of CD142-EV in SARS-CoV-2 infection.

Expression of CD142-EV was evaluated in 261 subjects admitted to hospital for pneumonia and with a positive molecular test for SARS-CoV-2. The study population consisted of a discovery cohort of selected patients (n = 60) and an independent validation cohort including unselected consecutive enrolled patients (n = 201). CD142-EV levels were correlated with post-hospitalization course of the disease and compared to the clinically available 4C Mortality Score as referral.

CD142-EV showed a reliable performance to predict patient prognosis in the discovery cohort (AUC = 0.906) with an accuracy of 81.7%, that was confirmed in the validation cohort (AUC = 0.736). Kaplan-Meier curves highlighted a high discrimination power in unselected subjects with CD142-EV being able to stratify the majority of patients according to their prognosis. We obtained a comparable accuracy, being not inferior in terms of prediction of patients' prognosis and risk of mortality, with 4C Mortality Score. The expression of surface vesicular CD142 and its reliability as prognostic marker was technically validated using different immunocapture strategies and assays.

The detection of CD142 on EV surface gains considerable interest as risk stratification tool to support clinical decision making in COVID-19.

A close-up view of dynamic biomarkers in the setting of COVID-19: Striking focus on cardiovascular system

Based on the recent reports, cardiovascular events encompass a large portion of the mortality caused by the COVID-19 pandemic, which drawn cardiologists into the management of the admitted ill patients. Given that common laboratory values may provide key insights into the illness caused by the life-threatening SARS-CoV-2 virus, it would be more helpful for screening, clinical management and on-time therapeutic strategies. Commensurate with these issues, this review article aimed to discuss the dynamic changes of the common laboratory parameters during COVID-19 and their association with cardiovascular diseases. Besides, the values that changed in the early stage of the disease were considered and monitored during the recovery process. The time required for returning biomarkers to basal levels was also discussed. Finally, of particular interest, we tended to abridge the latest updates regarding the cardiovascular biomarkers as prognostic and diagnostic criteria to determine the severity of COVID-19.

Angiotensin-converting enzyme 2: a key enzyme in key organs

2020 marked the 20th anniversary of the discovery of the angiotensin-converting enzyme 2 (ACE2). This major event that changed the way we see the renin-angiotensin system today could have passed quietly. Instead, the discovery that ACE2 is a major player in the severe acute respiratory syndrome coronavirus 2 pandemic has blown up the literature regarding this enzyme. ACE2 connects the classical arm renin-angiotensin system, consisting mainly of angiotensin II peptide and its AT1 receptor, with a protective arm, consisting mainly of the angiotensin 1-7 peptide and its Mas receptor. In this brief article, we have reviewed the literature to describe how ACE2 is a key protective arm enzyme in the function of many organs, particularly in the context of brain and cardiovascular function, as well as in renal, pulmonary and digestive homeostasis. We also very briefly review and refer to recent literature to present an insight into the role of ACE2 in determining the course of coronavirus diseases 2019.

Sex-related susceptibility in coronavirus disease 2019 (COVID-19): Proposed mechanisms

The importance of sex differences is increasingly acknowledged in the incidence and treatment of disease. Accumulating clinical evidence demonstrates that sex differences are noticeable in COVID-19, and the prevalence, severity, and mortality rate of COVID-19 are higher among males than females. Sex-related genetic and hormonal factors and immunological responses may underlie the sex bias in COVID-19 patients. Angiotensin-converting enzyme 2 (ACE2) and transmembrane protease/serine subfamily member 2 (TMPRSS2) are essential proteins involved in the cell entry of SARS-CoV-2. Since ACE2 is encoded on the X-chromosome, a double copy of ACE2 in females may compensate for virus-mediated downregulation of ACE2, and thus ACE2-mediated cellular protection is greater in females. The X chromosome also contains the largest immune-related genes leading females to develop more robust immune responses than males. Toll-like receptor-7 (TLR-7), one of the key players in innate immunity, is linked to sex differences in autoimmunity and vaccine efficacy, and its expression is greater in females. Sex steroids also affect immune cell function. Estrogen contributes to higher CD4⁺ and CD8⁺ T cell activation levels, and females have more B cells than males. Sex differences not only affect the severity and progression of the disease, but also alter the efficacy of pharmacological treatment and adverse events related to the drugs/vaccines used against COVID-19. Administration of different drugs/vaccines in different doses or intervals may be useful to eliminate sex differences in efficacy and side/adverse effects. It should be noted that studies should include sex-specific analyses to develop further sex-specific treatments for COVID-19.

Conjugated polymers mediate intracellular Ca2+ signals in circulating endothelial colony forming cells through the reactive oxygen species-dependent activation of Transient Receptor Potential Vanilloid 1 (TRPV1)

Endothelial colony forming cells (ECFCs) represent the most suitable cellular substrate to induce revascularization of ischemic tissues. Recently, optical excitation of the light-sensitive conjugated polymer, regioregular Poly (3-hexyl-thiophene), rr-P3HT, was found to stimulate ECFC proliferation and tube formation by activating the non-selective cation channel, Transient Receptor Potential Vanilloid 1 (TRPV1). Herein, we adopted a multidisciplinary approach, ranging from intracellular Ca²⁺ imaging to pharmacological manipulation and genetic suppression of TRPV1 expression, to investigate the effects of photoexcitation on intracellular Ca²⁺ concentration ([Ca²⁺]_i) in circulating ECFCs plated on rr-P3HT thin films. Polymer-mediated optical excitation induced a long-lasting increase in [Ca²⁺]_i that could display an oscillatory pattern at shorter light stimuli. Pharmacological and genetic manipulation revealed that the Ca²⁺ response to light was triggered by extracellular Ca²⁺ entry through TRPV1, whose activation required the production of reactive oxygen species at the interface between rr-P3HT and the cell membrane. Light-induced TRPV1-mediated Ca²⁺ entry was able to evoke intracellular Ca²⁺ release from the endoplasmic reticulum through inositol-1,4,5-trisphosphate receptors, followed by store-operated Ca²⁺ entry on the plasma membrane. These data show that TRPV1 may serve as a decoder at the interface between rr-P3HT thin films and ECFCs to translate optical excitation in pro-angiogenic Ca²⁺ signals.

DNA aptamers masking angiotensin converting enzyme 2 as an innovative way to treat SARS-CoV-2 pandemic

All the different coronavirus SARS-CoV-2 variants isolated so far share the same mechanism of infection mediated by the interaction of their spike (S) glycoprotein with specific residues on their cellular receptor: the angiotensin converting enzyme 2 (ACE2). Therefore, the steric hindrance on this cellular receptor created by a bulk macromolecule may represent an effective strategy for the prevention of the viral spreading and the onset of severe forms of Corona Virus disease 19 (COVID-19). Here, we applied a systematic evolution of ligands by exponential enrichment (SELEX) procedure to identify two single strand DNA molecules (aptamers) binding specifically to the region surrounding the K353, the key residue in human ACE2 interacting with the N501 amino acid of the SARS-CoV-2 S. 3D docking in silico experiments and biochemical assays demonstrated that these aptamers bind to this region, efficiently prevent the SARS-CoV-2 S/human ACE2 interaction and the viral infection in the nanomolar range, regardless of the viral variant, thus suggesting the possible clinical development of these aptamers as SARS-CoV-2 infection inhibitors. Our approach brings a significant innovation to the therapeutic paradigm of the SARS-CoV-2 pandemic by protecting the target cell instead of focusing on the virus; this is particularly attractive in light of the increasing number of viral mutants that may potentially escape the currently developed immune-mediated neutralization strategies.

Post-Acute Sequelae of COVID-19 and Cardiovascular Autonomic Dysfunction: What Do We Know?

Post-acute sequelae of SARS-CoV-2 (PASC), or long COVID syndrome, is emerging as a major health issue in patients with previous SARS-CoV-2 infection. Symptoms commonly experienced by patients include fatigue, palpitations, chest pain, dyspnea, reduced exercise tolerance, and “brain fog”. Additionally, symptoms of orthostatic intolerance and syncope suggest the involvement of the autonomic nervous system. Signs of cardiovascular autonomic dysfunction appear to be common in PASC and are similar to those observed in postural orthostatic tachycardia syndrome and inappropriate sinus tachycardia. In this review, we report on the epidemiology of PASC, discuss current evidence and possible mechanisms underpinning the dysregulation of the autonomic nervous system, and suggest nonpharmacological and pharmacological interventions to treat and relieve symptoms of PASC-associated dysautonomia.

Nanocarriers Loaded with Oxygen to Improve the Protection of the Heart to be Transplanted

In the case of serious cardiovascular diseases, such as refractory heart failure, heart transplantation is the only possible intervention. Currently, the modes of organ transport in hypothermic cardioplegic solution do not allow the implantation of the heart beyond 4-5 hours from the explant. The heart being an organ with a greater consumption of oxygen and high metabolism than the brain, its transport in hypothermic cardioplegic solutions presents critical issues in terms of time and conservation. An ambitious goal of many researchers and clinicians is to minimize the hypoxia of the explanted heart and extend the permanence time in cardioplegic solution without damage from hypoxia. Adequately oxygenating the explanted organs may extend the usability time of the explanted organ. This challenge has been pursued for years with approaches that are often expensive, risky, and/or difficult to use. We propose to consider oxygenated nanocarriers realizing oxygen for a long time. In this way, it will also be possible to use organs from distant countries with respect to the recipient, thus exceeding the canonical 4-5 hours tolerated up to now. In addition to the lack of oxygen, the transplanted organ can undergo the accumulation of catabolites due to the lack of perfusion during transport. Therefore, nanocarriers can also be perfused in adequate solution during organ transportation. A better oxygenation improving the postoperative recovery of the transplanted heart will improve the recipient's quality of life.

Reactive Oxygen Species and Endothelial Ca2+ Signaling: Brothers in Arms or Partners in Crime?

An increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) controls virtually all endothelial cell functions and is, therefore, crucial to maintain cardiovascular homeostasis. An aberrant elevation in endothelial can indeed lead to severe cardiovascular disorders. Likewise, moderate amounts of reactive oxygen species (ROS) induce intracellular Ca²⁺ signals to regulate vascular functions, while excessive ROS production may exploit dysregulated Ca²⁺ dynamics to induce endothelial injury. Herein, we survey how ROS induce endothelial Ca²⁺ signals to regulate vascular functions and, vice versa, how aberrant ROS generation may exploit the Ca²⁺ handling machinery to promote endothelial dysfunction. ROS elicit endothelial Ca²⁺ signals by regulating inositol-1,4,5-trisphosphate receptors, sarco-endoplasmic reticulum Ca²⁺-ATPase 2B, two-pore channels, store-operated Ca²⁺ entry (SOCE), and multiple isoforms of transient receptor potential (TRP) channels. ROS-induced endothelial Ca²⁺ signals regulate endothelial permeability, angiogenesis, and generation of vasorelaxing mediators and can be exploited to induce therapeutic angiogenesis, rescue neurovascular coupling, and induce cancer regression. However, an increase in endothelial [Ca²⁺]_i induced by aberrant ROS formation may result in endothelial dysfunction, inflammatory diseases, metabolic disorders, and pulmonary artery hypertension. This information could pave the way to design alternative treatments to interfere with the life-threatening interconnection between endothelial ROS and Ca²⁺ signaling under multiple pathological conditions.

Posttraumatic Stress Disorder and Cardiovascular Disease: State of the Science, Knowledge Gaps, and Research Opportunities

Posttraumatic stress disorder (PTSD) is characterized by a persistent maladaptive reaction after exposure to severe psychological trauma. Traumatic events that may precipitate PTSD include violent personal assaults, natural and human-made disasters, and exposure to military combat or warfare. There is a growing body of evidence for associations of PTSD with major risk factors for cardiovascular disease (CVD), such as hypertension and diabetes, as well as with major CVD outcomes, such as myocardial infarction and heart failure. However, it is unclear whether these associations are causal or confounded. Furthermore, the biological and behavioral mechanisms underlying these associations are poorly understood. Here, the available evidence on the association of PTSD with CVD from population, basic, and genomic research as well as from clinical and translational research are reviewed, seeking to identify major research gaps, barriers, and opportunities in knowledge acquisition and technology as well as research tools to support and accelerate critical research for near-term and longer-term translational research directions. Large-scale, well-designed prospective studies, capturing diverse and high-risk populations, are warranted that include uniform phenotyping of PTSD as well as broad assessment of biological and behavioral risk factors and CVD outcomes. Available evidence from functional brain imaging studies demonstrates that PTSD pathophysiology includes changes in specific anatomical brain regions and circuits, and studies of immune system function in individuals with PTSD suggest its association with enhanced immune inflammatory activity. However, establishment of animal models and human tissue biobanks is also warranted to elucidate the potential causal connection of PTSD-induced brain changes and/or inflammation with CVD pathophysiology. Emerging large-scale genome-wide association studies of PTSD will provide an opportunity to conduct mendelian randomization studies that test hypotheses regarding the presence, magnitude, and direction of causal associations between PTSD and CVD outcomes. By identifying research gaps in epidemiology and genomics, animal, and human translational research, opportunities to better justify and design future interventional trials are highlighted that may test whether treatment of PTSD or underlying neurobiological or immune dysregulation may improve or prevent CVD risk or outcomes.

Sinus bradycardia is associated with poor outcome in critically ill patients with COVID-19 due to the B.1.1.7 Lineage

The progress of COVID-19 from moderate to severe may be precipitous, while the characteristics of the disease are heterogenous. The aim of this study was to describe the development of sinus bradycardia in critically ill patients with COVID-19 and its association with outcome in outbreak due to the SARS-CoV-2 B.1.1.7 Lineage. We leveraged the multi-center SuPAR in Adult Patients With COVID-19 (SPARCOL) study and identified patients who required admission to intensive care unit (ICU). Inclusion criteria were: (a) adult (≥18 years old) patients hospitalized primarily for COVID-19; (b) a confirmed SARS-CoV-2 infection diagnosed through reverse transcriptase polymerase chain reaction test of nasopharyngeal or oropharyngeal samples; and (c) at least one blood sample collected at admission and stored for suPAR, hs-CRP, and ferritin testing. All patients had continuous heart rate monitoring during hospitalization. In total, 81 patients were included. Of them, 17 (21 %) and 64 (79 %) were intubated and admitted to the ICU during the first and second wave, respectively. Two (12 %) and 62 (97 %) developed bradycardia before ICU admission, respectively (p < 0.001). Patients with bradycardia had increased suPAR (p < 0.001) and hs-CRP level (p < 0.001). Infusion of isoprenaline and/or noradrenaline was necessary to maintain an adequate rate and peripheral perfusion in all patients. Mortality was significantly higher in patients with bradycardia (p < 0.001). In conclusion, bradycardia was associated with poor outcome. As B.1.1.7 variant strain is spreading more rapidly in many countries, our findings help in the identification of patients who may require early admission to ICU.