Endothelial dysfunction in long-COVID: New insights from the nationwide multicenter LINCOLN Study

Cerebromicrovascular mechanisms contributing to long COVID: implications for neurocognitive health

Long COVID (also known as post-acute sequelae of SARS-CoV-2 infection [PASC] or post-COVID syndrome) is characterized by persistent symptoms that extend beyond the acute phase of SARS-CoV-2 infection, affecting approximately 10% to over 30% of those infected. It presents a significant clinical challenge, notably due to pronounced neurocognitive symptoms such as brain fog. The mechanisms underlying these effects are multifactorial, with mounting evidence pointing to a central role of cerebromicrovascular dysfunction. This review investigates key pathophysiological mechanisms contributing to cerebrovascular dysfunction in long COVID and their impacts on brain health. We discuss how endothelial tropism of SARS-CoV-2 and direct vascular infection trigger endothelial dysfunction, impaired neurovascular coupling, and blood-brain barrier disruption, resulting in compromised cerebral perfusion. Furthermore, the infection appears to induce mitochondrial dysfunction, enhancing oxidative stress and inflammation within cerebral endothelial cells. Autoantibody formation following infection also potentially exacerbates neurovascular injury, contributing to chronic vascular inflammation and ongoing blood-brain barrier compromise. These factors collectively contribute to the emergence of white matter hyperintensities, promote amyloid pathology, and may accelerate neurodegenerative processes, including Alzheimer's disease. This review also emphasizes the critical role of advanced imaging techniques in assessing cerebromicrovascular health and the need for targeted interventions to address these cerebrovascular complications. A deeper understanding of the cerebrovascular mechanisms of long COVID is essential to advance targeted treatments and mitigate its long-term neurocognitive consequences.

Increased prevalence of cardiovascular-kidney-metabolic syndrome during COVID-19: A propensity score-matched study

A recent presidential advisory from the American Heart Association (AHA) has introduced the term cardiovascular-kidney-metabolic (CKM) syndrome to describe the complex interplay among health conditions linking heart, kidney, and metabolism. The aim of our study was to compare the prevalence of concurrent CKM syndrome components before and during the COVID-19 pandemic and identify associated risk factors. We conducted a study utilizing data from a real-world population obtained from a primary care database. The study cohort comprised a closed group followed over a 6-year period (2017-2022). A total of 81,051 individuals were included: 32,650 in the pre-pandemic period and 48,401 in the 2020-2022 triennium. After propensity-score matching for sex, age, and BMI, the study included 30,511 participants for each period. 3554 individuals were diagnosed with type 2 diabetes in the pre-pandemic period, compared to 7430 during the pandemic. Hypertension, dyslipidemia, and obesity displayed significant increases in prevalence during the pandemic, and prediabetes had a particularly sharp rise of 170%. Age-stratified analyses revealed a higher burden of CKM conditions with advancing age. Our findings indicate a substantial increase in the prevalence of CKM syndrome during the COVID-19 pandemic, with nearly half of the patients exhibiting one or more CKM syndrome components.

The relationship between COVID-19 and hyperglycemia: screening and monitoring hospitalized patients

BACKGROUND

Elevated blood glucose concentration, also known as hyperglycemia, has been identified as a significant factor influencing the prognosis of COVID-19, alongside the impact of the SARS-CoV-2 infection itself.

METHODS

This research is a cross-sectional investigation that examined the relationship between COVID-19 and hyperglycemia in patients admitted to Afzalipour Hospital in Kerman, Iran, from July to September 2021. A standardized data sheet was used to capture demographic data (age, gender) and laboratory information (blood sugar, arterial blood oxygen saturation, and C-reactive protein (CRP)) upon admission.

RESULTS

The present research evaluated a total of 300 individuals diagnosed with COVID-19, with an average age of 50.19 ± 15.55 years. Among these patients, the majority were male, accounting for 51.67% of the total. Hyperglycemia was seen in 21.67% of patients, but less than 20% had new-onset diabetes. Individuals exhibiting hyperglycemia were typical of advanced age (P < 0.001). Furthermore, there was a slight but statistically significant association between advanced age and elevated blood glucose concentration (R = 0.254, P < 0.001). Gender had no significant impact on the occurrence of hyperglycemia (P = 0.199). There was no significant association between CRP levels and blood glucose concentration (P = 0.524) or the incidence of hyperglycemia (P = 0.473). Although there was no significant disparity in blood oxygen saturation between individuals with or without hyperglycemia (P = 0.06), higher blood glucose concentration was correlated with lower blood oxygen saturation (R = -0.151, P < 0.001).

CONCLUSION

Considering the correlation between blood glucose concentration, advanced age, and disease severity, it is recommended to carefully screen and monitor all COVID-19 patients for hyperglycemia and new-onset diabetes. Effective management of these complications could enhance the control of patients' overall prognosis and subsequent complications.

Human herpesvirus reactivation and its potential role in the pathogenesis of post-acute sequelae of SARS-CoV-2 infection

The emergence of SARS-CoV-2 has precipitated a global pandemic with substantial long-term health implications, including the condition known as post-acute sequelae of SARS-CoV-2 infection (PASC), commonly referred to as Long COVID. PASC is marked by persistent symptoms such as fatigue, neurological issues, and autonomic dysfunction that persist for months beyond the acute phase of COVID-19. This review examines the potential role of herpesvirus reactivation, specifically Epstein-Barr virus (EBV) and cytomegalovirus (CMV), in the pathogenesis of PASC. Elevated antibody titers and specific T cell responses suggest recent herpesvirus reactivation in some PASC patients, although viremia is not consistently detected. SARS-CoV-2 exhibits endothelial trophism, directly affecting the vascular endothelium and contributing to microvascular pathologies. These pathologies are significant in PASC, where microvascular dysfunction may underlie various chronic symptoms. Similarly, herpesviruses like CMV also exhibit endothelial trophism, which may exacerbate endothelial damage when reactivated. Evidence suggests that EBV and CMV reactivation could indirectly contribute to the immune dysregulation, immunosenescence, and autoimmune responses observed in PASC. Additionally, EBV may play a role in the genesis of neurological symptoms through creating mitochondrial dysfunction, though direct confirmation remains elusive. The reviewed evidence suggests that while herpesviruses may not play a direct role in the pathogenesis of PASC, their potential indirect effects, especially in the context of endothelial involvement, warrant further investigation.

Dietary Supplements in Cardiovascular and Metabolic Diseases

Recent research has sparked increasing interest in the effects of dietary supplements on cardiovascular and metabolic disorders [...].

Endothelial Extracellular Vesicles Enriched in microRNA-34a Predict New-Onset Diabetes in Coronavirus Disease 2019 (COVID-19) Patients: Novel Insights for Long COVID Metabolic Sequelae

Emerging evidence indicates that the relationship between coronavirus disease 2019 (COVID-19) and diabetes is 2-fold: 1) it is known that the presence of diabetes and other metabolic alterations poses a considerably high risk to develop a severe COVID-19; 2) patients who survived a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have an increased risk of developing new-onset diabetes. However, the mechanisms underlying this association are mostly unknown, and there are no reliable biomarkers to predict the development of new-onset diabetes. In the present study, we demonstrate that a specific microRNA (miR-34a) contained in circulating extracellular vesicles released by endothelial cells reliably predicts the risk of developing new-onset diabetes in COVID-19. This association was independent of age, sex, body mass index (BMI), hypertension, dyslipidemia, smoking status, and D-dimer. SIGNIFICANCE STATEMENT: We demonstrate for the first time that a specific microRNA (miR-34a) contained in circulating extracellular vesicles released by endothelial cells is able to reliably predict the risk of developing diabetes after having contracted coronavirus disease 2019 (COVID-19). This association was independent of age, sex, body mass index (BMI), hypertension, dyslipidemia, smoking status, and D-dimer. Our findings are also relevant when considering the emerging importance of post-acute sequelae of COVID-19, with systemic manifestations observed even months after viral negativization (long COVID).

Low-dose Naltrexone Improves post-COVID-19 condition Symptoms

PURPOSE

Treatments for myalgic encephalomyelitis and chronic fatigue syndrome can be adapted for post-COVID-19 condition. Our aim was to compare treatments in patients from our post-COVID-19 clinic.

METHODS

We conducted a retrospective cohort study and included consecutive patients enrolled in our post-COVID-19 clinic. We included patients who received low-dose naltrexone, amitriptyline, duloxetine, and physical therapy, and evaluated improvements in fatigue, pain, dyspnea, and brain fog recorded in the electronic health record. We calculated the adjusted relative hazard of improvement using Cox proportional models. We adjusted for demographic characteristics, comorbidities, and prior COVID-19 hospitalization.

FINDINGS

We included the first 108 patients with post-COVID-19 enrolled in the clinic. Most of the patients received amitriptyline. The relative hazard of improvement for those taking low-dose naltrexone was 5.04 (95% CI, 1.22-20.77; P = 0.02) compared with physical therapy alone. Both fatigue and pain were improved in patients taking low-dose naltrexone; only fatigue was improved in patients taking amitriptyline.

IMPLICATIONS

Post-COVID-19 condition symptoms may improve in patients taking medications adapted from myalgic encephalomyelitis and chronic fatigue syndrome. Randomized controlled trials should evaluate these medications and translational studies should further evaluate their mechanisms of action.

Visual analysis of hotspots and trends in long COVID research based on bibliometric

After severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, a series of symptoms may persist for a long time, which is now called long COVID. It was found that long COVID can affect all patients with COVID-19. Therefore, long COVID has become a hot topic. In this study, we used the WOS database as a sample data source to conduct a bibliometric and visual analysis of 1765 long COVID articles over the past three years through VOSviewer and R package. The results show that countries/authors in Europe and The United States of America contribute most of the articles, and their cooperation is also the most active. Keyword co-occurrence identified four clusters, with important topics including the mechanism, clinical symptoms, epidemiological characteristics, and management/treatment of long COVID. Themes such as "cognitive impairment", "endothelial dysfunction", "diagnosis", and "biomarkers" are likely to be the focus of new attention in the coming period. In addition, we put forward the possible research opportunities on long COVID for researchers and practitioners to facilitate future research.

The long-term health outcomes, pathophysiological mechanisms and multidisciplinary management of long COVID

There have been hundreds of millions of cases of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the growing population of recovered patients, it is crucial to understand the long-term consequences of the disease and management strategies. Although COVID-19 was initially considered an acute respiratory illness, recent evidence suggests that manifestations including but not limited to those of the cardiovascular, respiratory, neuropsychiatric, gastrointestinal, reproductive, and musculoskeletal systems may persist long after the acute phase. These persistent manifestations, also referred to as long COVID, could impact all patients with COVID-19 across the full spectrum of illness severity. Herein, we comprehensively review the current literature on long COVID, highlighting its epidemiological understanding, the impact of vaccinations, organ-specific sequelae, pathophysiological mechanisms, and multidisciplinary management strategies. In addition, the impact of psychological and psychosomatic factors is also underscored. Despite these crucial findings on long COVID, the current diagnostic and therapeutic strategies based on previous experience and pilot studies remain inadequate, and well-designed clinical trials should be prioritized to validate existing hypotheses. Thus, we propose the primary challenges concerning biological knowledge gaps and efficient remedies as well as discuss the corresponding recommendations.

Beneficial Effects of L-Arginine in Patients Hospitalized for COVID-19: New Insights from a Randomized Clinical Trial

We have recently demonstrated in a double-blind randomized trial the beneficial effects of L-Arginine in patients hospitalized for COVID-19. We hypothesize that one of the mechanisms underlying the favorable effects of L-Arginine is its action on inflammatory cytokines. To verify our hypothesis, we measured longitudinal plasma levels of pro-inflammatory and anti-inflammatory cytokines implied in the pathophysiology of COVID-19 in patients randomized to receive oral L-Arginine or placebo. The study was successfully completed by 169 patients. Patients in the L-Arginine arm had a reduced respiratory support evaluated at 10 and 20 days; moreover, the time to hospital discharge was significantly shorter in the L-Arginine group. The assessment of circulating cytokines revealed that L-Arginine significantly reduced the circulating levels of pro-inflammatory IL-2, IL-6, and IFN-γ and increased the levels of the anti-inflammatory IL-10. Taken together, these findings indicate that adding L-Arginine to standard therapy in COVID-19 patients markedly reduces the need of respiratory support and the duration of in-hospital stay; moreover, L-Arginine significantly regulates circulating levels of pro-inflammatory and anti-inflammatory cytokines.

COVID-19 Causes Ferroptosis and Oxidative Stress in Human Endothelial Cells

Oxidative stress and endothelial dysfunction have been shown to play crucial roles in the pathophysiology of COVID-19 (coronavirus disease 2019). On these grounds, we sought to investigate the impact of COVID-19 on lipid peroxidation and ferroptosis in human endothelial cells. We hypothesized that oxidative stress and lipid peroxidation induced by COVID-19 in endothelial cells could be linked to the disease outcome. Thus, we collected serum from COVID-19 patients on hospital admission, and we incubated these sera with human endothelial cells, comparing the effects on the generation of reactive oxygen species (ROS) and lipid peroxidation between patients who survived and patients who did not survive. We found that the serum from non-survivors significantly increased lipid peroxidation. Moreover, serum from non-survivors markedly regulated the expression levels of the main markers of ferroptosis, including GPX4, SLC7A11, FTH1, and SAT1, a response that was rescued by silencing TNFR1 on endothelial cells. Taken together, our data indicate that serum from patients who did not survive COVID-19 triggers lipid peroxidation in human endothelial cells.