COVID-19-induced endotheliitis: emerging evidence and possible therapeutic strategies

Endothelial injury and dysfunction with emerging immunotherapies in multiple myeloma, the impact of COVID-19, and endothelial protection with a focus on the evolving role of defibrotide

Patients with multiple myeloma (MM) were among the groups impacted more severely by the COVID-19 pandemic, with higher rates of severe disease and COVID-19-related mortality. MM and COVID-19, plus post-acute sequelae of SARS-CoV-2 infection, are associated with endothelial dysfunction and injury, with overlapping inflammatory pathways and coagulopathies. Existing treatment options for MM, notably high-dose therapy with autologous stem cell transplantation and novel chimeric antigen receptor (CAR) T-cell therapies and bispecific T-cell engaging antibodies, are also associated with endothelial cell injury and mechanism-related toxicities. These pathologies include cytokine release syndrome (CRS) and neurotoxicity that may be exacerbated by underlying endotheliopathies. In the context of these overlapping risks, prophylaxis and treatment approaches mitigating the inflammatory and pro-coagulant effects of endothelial injury are important considerations for patient management, including cytokine receptor antagonists, thromboprophylaxis with low-molecular-weight heparin and direct oral anticoagulants, and direct endothelial protection with defibrotide in the appropriate clinical settings.

Acute Myocardial Infarction in COVID-19 Patients-A Review of Literature Data and Two-Case Report Series

Background/Objectives: The newly emergent COVID-19 pandemic involved primarily the respiratory system and had also major cardiovascular system (CVS) implications, revealed by acute myocardial infarction (AMI), arrhythmias, myocardial injury, and thromboembolism. CVS involvement is done through main mechanisms-direct and indirect heart muscle injury, with high mortality rates, worse short-term outcomes, and severe complications. AMI is the echo of myocardial injury (revealed by increases in CK, CK-MB, and troponin serum markers-which are taken into consideration as possible COVID-19 risk stratification markers). When studying myocardial injury, physicians can make use of imaging studies, such as cardiac MRI, transthoracic (or transesophageal) echocardiography, coronary angiography, cardiac computed tomography, and nuclear imaging (which have been used in cases where angiography was not possible), or even endomyocardial biopsy (which is not always available or feasible). Two-case-series presentations: We present the cases of two COVID-19 positive male patients who were admitted into the Clinical Department of Cardiology in "Sfântul Apostol Andrei" Emergency Clinical Hospital of Galați (Romania), who presented with acute cardiac distress symptoms and have been diagnosed with ST elevation AMI. The patients were 82 and 57 years old, respectively, with moderate and severe forms of COVID-19, and were diagnosed with anteroseptal left ventricular AMI and extensive anterior transmural left ventricular AMI (with ventricular fibrillation at presentation), respectively. The first patient was a non-smoker and non-drinker with no associated comorbidities, and was later discharged, while the second one died due to AMI complications. Conclusions: From this two-case series, we extract the following: old age alone is not a significant risk factor for adverse outcomes in COVID-19-related CVS events, and that the cumulative effects of several patient-associated risk factors (be it either for severe forms of COVID-19 and/or acute cardiac injury) will most probably lead to poor patient prognosis (death). At the same time, serum cardiac enzymes, dynamic ECG changes, along with newly developed echocardiographic modifications are indicators for poor prognosis in acute cardiac injury in COVID-19 patients with acute myocardial injury, regardless of the presence of right ventricular dysfunction (due to pulmonary hypertension).

The Role of Heparin in Postural Orthostatic Tachycardia Syndrome and Other Post-Acute Sequelae of COVID-19

The therapeutic management and short-term consequences of the coronavirus disease 2019 (COVID-19) are well known. However, COVID-19 post-acute sequelae are less known and represent a public health problem worldwide. Patients with COVID-19 who present post-acute sequelae may display immune dysregulation, a procoagulant state, and persistent microvascular endotheliopathy that could trigger microvascular thrombosis. These elements have also been implicated in the physiopathology of postural orthostatic tachycardia syndrome, a frequent sequela in post-COVID-19 patients. These mechanisms, directly associated with post-acute sequelae, might determine the thrombotic consequences of COVID-19 and the need for early anticoagulation therapy. In this context, heparin has several potential benefits, including immunomodulatory, anticoagulant, antiviral, pro-endothelial, and vascular effects, that could be helpful in the treatment of COVID-19 post-acute sequelae. In this article, we review the evidence surrounding the post-acute sequelae of COVID-19 and the potential benefits of the use of heparin, with a special focus on the treatment of postural orthostatic tachycardia syndrome.

Effect of polyphenols against complications of COVID-19: current evidence and potential efficacy

The COVID-19 pandemic that started in 2019 and resulted in significant morbidity and mortality continues to be a significant global health challenge, characterized by inflammation, oxidative stress, and immune system dysfunction.. Developing therapies for preventing or treating COVID-19 remains an important goal for pharmacology and drug development research. Polyphenols are effective against various viral infections and can be extracted and isolated from plants without losing their therapeutic potential. Researchers have developed methods for separating and isolating polyphenols from complex matrices. Polyphenols are effective in treating common viral infections, including COVID-19, and can also boost immunity. Polyphenolic-based antiviral medications can mitigate SARS-CoV-2 enzymes vital to virus replication and infection. Individual polyphenolic triterpenoids, flavonoids, anthraquinonoids, and tannins may also inhibit the SARS-CoV-2 protease. Polyphenol pharmacophore structures identified to date can explain their action and lead to the design of novel anti-COVID-19 compounds. Polyphenol-containing mixtures offer the advantages of a well-recognized safety profile with few known severe side effects. However, studies to date are limited, and further animal studies and randomized controlled trials are needed in future studies. The purpose of this study was to review and present the latest findings on the therapeutic impact of plant-derived polyphenols on COVID-19 infection and its complications. Exploring alternative approaches to traditional therapies could aid in developing novel drugs and remedies against coronavirus infection.

Vascular Endothelial Growth Factor as Potential Biomarker for COVID-19 Severity

INTRODUCTION

COVID-19 is characterized by immunological responses to viral replication and coherent with endothelitis, microvascular disturbance of lung vasculature and coagulopathy. Vascular Endothelial Growth Factor (VEGF) is a proangiogenic mediator regulating endothelial changes. It is induced by proinflammatory signaling and hypoxia. We sought to determine whether VEGF levels differ between SARS-CoV-2-positive patients of different disease severity and whether VEGF might be useful in risk stratification.

METHODS

After retrospective screening of all SARS-CoV-2-positive patients treated in Unfallkrankenhaus Berlin in 2020, we included those with documented VEGF measurement. We extracted laboratory values and clinical parameters. An exploratory data analysis was performed to detect possible relations between VEGF level and clinical disease features.

RESULTS

We included 167 SARS-CoV-2-positive patients of which 139 suffered from COVID-19. Seventy-one of the COVID-19 patients had to be treated in the intensive care unit (ICU), those patients exhibited higher VEGF levels than those being admitted to normal wards (535 vs 279 pg/L, P < .001). APACHE-2 (Acute Physiology And Chronic Health Evaluation Score) correlated with mortality and patients with high values showed higher VEGF concentrations on admission (456 vs 875 pg/L, p = 0.006). Receiver operating characteristic analytic revealed that the occurrence of organ dysfunctions like acute respiratory distress syndrome (ARDS), shock, or acute kidney injury could be predicted by VEGF. It was significantly higher in patients who later died compared to survivors (637 vs 389 pg/mL, P = 0.041) and predicted mortality with same accuracy as established markers. In our cohort, association of VEGF above 277 pg/L on admission with risk of ARDS could be confirmed in logistic regression adjusting for possible confounding factors (odds ratio 3.1, 95% confidence interval: 1.34-7.7).

DISCUSSION

Even though there are several limitations to this retrospective study it revealed that in COVID-19 patients VEGF can contribute to the prediction of necessity of ICU, mortality and the prediction of ARDS, kidney injury or shock. Its use in risk stratification and potential pathogenetic involvement should be further investigated.

Endothelial activation and damage as a common pathological substrate in different pathologies and cell therapy complications

The endothelium is a biologically active interface with multiple functions, some of them common throughout the vascular tree, and others that depend on its anatomical location. Endothelial cells are continually exposed to cellular and humoral factors, and to all those elements (biological, chemical, or hemodynamic) that circulate in blood at a certain time. It can adapt to different stimuli but this capability may be lost if the stimuli are strong enough and/or persistent in time. If the endothelium loses its adaptability it may become dysfunctional, becoming a potential real danger to the host. Endothelial dysfunction is present in multiple clinical conditions, such as chronic kidney disease, obesity, major depression, pregnancy-related complications, septic syndromes, COVID-19, and thrombotic microangiopathies, among other pathologies, but also in association with cell therapies, such as hematopoietic stem cell transplantation and treatment with chimeric antigen receptor T cells. In these diverse conditions, evidence suggests that the presence and severity of endothelial dysfunction correlate with the severity of the associated disease. More importantly, endothelial dysfunction has a strong diagnostic and prognostic value for the development of critical complications that, although may differ according to the underlying disease, have a vascular background in common. Our multidisciplinary team of women has devoted many years to exploring the role of the endothelium in association with the mentioned diseases and conditions. Our research group has characterized some of the mechanisms and also proposed biomarkers of endothelial damage. A better knowledge would provide therapeutic strategies either to prevent or to treat endothelial dysfunction.

Glucose metabolism disorder: a potential accomplice of SARS-CoV-2

Globally, 265,713,467 confirmed cases of SARS-CoV-2 (CoV-2), including 5,260,888 deaths, have been reported by the WHO. It is important to study the mechanism of this infectious disease. A variety of evidences show the potential association between CoV-2 and glucose metabolism. Notably, people with type 2 diabetes mellitus (T2DM) and other metabolic complications were prone to have a higher risk of developing a more severe infection course than people who were metabolically normal. The correlations between glucose metabolism and CoV-2 progression have been widely revealed. This review will discuss the association between glucose metabolism disorders and CoV-2 progression, showing the promoting effect of diabetes and other diseases related to glucose metabolism disorders on the progression of CoV-2. We will further conclude the effects of key proteins and pathways in glucose metabolism regulation on CoV-2 progression and potential interventions by targeting glucose metabolism disorders for CoV-2 treatment. Therefore, this review will provide systematic insight into the treatment of CoV-2 from the perspective of glucose metabolism.

Rationale for combined therapies in severe-to-critical COVID-19 patients

An unprecedented global social and economic impact as well as a significant number of fatalities have been brought on by the coronavirus disease 2019 (COVID-19), produced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Acute SARS-CoV-2 infection can, in certain situations, cause immunological abnormalities, leading to an anomalous innate and adaptive immune response. While most patients only experience mild symptoms and recover without the need for mechanical ventilation, a substantial percentage of those who are affected develop severe respiratory illness, which can be fatal. The absence of effective therapies when disease progresses to a very severe condition coupled with the incomplete understanding of COVID-19's pathogenesis triggers the need to develop innovative therapeutic approaches for patients at high risk of mortality. As a result, we investigate the potential contribution of promising combinatorial cell therapy to prevent death in critical patients.

Immune responses of patients on maintenance hemodialysis after infection by SARS-CoV-2: a prospective observational cohort study

BACKGROUND

Immune dysregulation in patients with acute COVID-19 under chronic hemodialysis (CHD) is fully not elucidated. The changes of mononuclear counts and mediators before and after HD and associations with final outcome were studied.

METHOD

In this prospective study, hospitalized patients with moderate-to-severe COVID-19 under CHD and matched comparators under HD were analyzed for their absolute counts of lymphoid cells and circulating inflammatory mediators. Blood samples were collected before start and at the end of the first HD session; dialysate samples were also collected.

RESULT

Fifty-nine patients with acute COVID-19 under CHD and 20 uninfected comparators under CHD were enrolled. Circulating concentrations of tumor necrosis factor-alpha (TNFα), interleukin (IL)-10, interferon-γ and platelet-derived growth factor-A were increased in patients. Concentrations of mediators did not differ before and after HD. Significant decreases of CD4-lymphocytes and CD19-lymphocytes were found in patients. The decrease of the expression of HLA-DR on CD14-monocytes was associated with unfavorable outcome (defined as WHO-CPS 6 or more by day 28); increased counts of CD19-lymphocytes were associated with better outcomes.

CONCLUSION

Patients under CHD develop an inflammatory reaction to SARS-CoV-2 characterized by increase of inflammatory mediators, decrease of circulating T-lymphocytes and decrease of the expression of HLA-DR on CD14-monocytes.

TCM "medicine and food homology" in the management of post-COVID disorders

Background

The World Health Organization declared that COVID-19 is no longer a public health emergency of global concern on May 5, 2023. Post-COVID disorders are, however, becoming more common. Hence, there lies a growing need to develop safe and effective treatment measures to manage post-COVID disorders. Investigating the use of TCM medicinal foods in the long-term therapy of post-COVID illnesses may be beneficial given contemporary research's emphasis on the development of medicinal foods.

Scope and approach

The use of medicinal foods for the long-term treatment of post-COVID disorders is highlighted in this review. Following a discussion of the history of the TCM "Medicine and Food Homology" theory, the pathophysiological effects of post-COVID disorders will be briefly reviewed. An analysis of TCM medicinal foods and their functions in treating post-COVID disorders will then be provided before offering some insight into potential directions for future research and application.

Key findings and discussion

TCM medicinal foods can manage different aspects of post-COVID disorders. The use of medicinal foods in the long-term management of post-COVID illnesses may be a safe and efficient therapy choice because they are typically milder in nature than chronic drug use. These findings may also be applied in the long-term post-disease treatment of similar respiratory disorders.

Refueling the post COVID-19 brain: potential role of ketogenic medium chain triglyceride supplementation: an hypothesis

COVID-19 infection causes cognitive changes in the acute phase, but also after apparent recovery. Over fifty post (long)-COVID symptoms are described, including cognitive dysfunction ("brain fog") precluding return to pre-COVID level of function, with rates twice as high in females. Additionally, the predominant demographic affected by these symptoms is younger and still in the workforce. Lack of ability to work, even for six months, has significant socio-economic consequences. This cognitive dysfunction is associated with impaired cerebral glucose metabolism, assessed using 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET), showing brain regions that are abnormal compared to age and sex matched controls. In other cognitive conditions such as Alzheimer's disease (AD), typical patterns of cerebral glucose hypometabolism, frontal hypometabolism and cerebellar hypermetabolism are common. Similar FDG-PET changes have also been observed in post-COVID-19, raising the possibility of a similar etiology. Ketone bodies (B-hydroxybutyrate, acetoacetate and acetone) are produced endogenously with very low carbohydrate intake or fasting. They improve brain energy metabolism in the face of cerebral glucose hypometabolism in other conditions [mild cognitive impairment (MCI) and AD]. Long-term low carbohydrate intake or prolonged fasting is not usually feasible. Medium chain triglyceride (MCT) is an exogenous route to nutritional ketosis. Research has supported their efficacy in managing intractable seizures, and cognitive impairment in MCI and AD. We hypothesize that cerebral glucose hypometabolism associated with post COVID-19 infection can be mitigated with MCT supplementation, with the prediction that cognitive function would also improve. Although there is some suggestion that post COVID-19 cognitive symptoms may diminish over time, in many individuals this may take more than six months. If MCT supplementation is able to speed the cognitive recovery, this will impact importantly on quality of life. MCT is readily available and, compared to pharmaceutical interventions, is cost-effective. Research shows general tolerability with dose titration. MCT is a component of enteral and parenteral nutrition supplements, including in pediatrics, so has a long record of safety in vulnerable populations. It is not associated with weight gain or adverse changes in lipid profiles. This hypothesis serves to encourage the development of clinical trials evaluating the impact of MCT supplementation on the duration and severity of post COVID-19 cognitive symptoms.

Pathophysiological effects of SARS-CoV-2 infection on the cardiovascular system and its clinical manifestations-a mini review

Coronavirus disease 2019 (COVID-19) is a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 may have a mild presentation, with few symptoms, or progress to a severe condition, characterized by generalized inflammation, systemic microvascular involvement, coagulopathy, and pulmonary and cardiovascular complications. Men present with more severe symptoms than women, especially men who are older and who present with comorbidities such as hypertension, diabetes mellitus, and a history of atherosclerotic diseases. Owing to its association with endothelial dysfunction, inflammation, thrombosis, and microvascular obstruction, SARS-CoV-2 infection can cause lesions in several organs, including the myocardium and the coronary arterial bed, which can result in clinical manifestations involving the cardiovascular system. In this mini review, we summarize the effects of SARS-CoV-2 infection on the cardiovascular system in both children and adults and characterize the various clinical manifestations associated with this disease.

TLRs: Innate Immune Sentries against SARS-CoV-2 Infection

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been responsible for a devastating pandemic since March 2020. Toll-like receptors (TLRs), crucial components in the initiation of innate immune responses to different pathogens, trigger the downstream production of pro-inflammatory cytokines, interferons, and other mediators. It has been demonstrated that they contribute to the dysregulated immune response observed in patients with severe COVID-19. TLR2, TLR3, TLR4 and TLR7 have been associated with COVID-19 severity. Here, we review the role of TLRs in the etiology and pathogenesis of COVID-19, including TLR7 and TLR3 rare variants, the L412F polymorphism in TLR3 that negatively regulates anti-SARS-CoV-2 immune responses, the TLR3-related cellular senescence, the interaction of TLR2 and TLR4 with SARS-CoV-2 proteins and implication of TLR2 in NET formation by SARS-CoV-2. The activation of TLRs contributes to viral clearance and disease resolution. However, TLRs may represent a double-edged sword which may elicit dysregulated immune signaling, leading to the production of proinflammatory mediators, resulting in severe disease. TLR-dependent excessive inflammation and TLR-dependent antiviral response may tip the balance towards the former or the latter, altering the equilibrium that drives the severity of disease.

Cholinergic dysfunction in COVID-19: frantic search and hoping for the best

A novel coronavirus known as severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is a potential cause of acute respiratory infection called coronavirus disease 2019 (COVID-19). The binding of SARS-CoV-2 with angiotensin-converting enzyme 2 (ACE2) induces a series of inflammatory cellular events with cytopathic effects leading to cell injury and hyperinflammation. Severe SARS-CoV-2 infection may lead to dysautonomia and sympathetic storm due to dysfunction of the autonomic nervous system (ANS). Therefore, this review aimed to elucidate the critical role of the cholinergic system (CS) in SARS-CoV-2 infection. The CS forms a multi-faceted network performing diverse functions in the body due to its distribution in the neuronal and non-neuronal cells. Acetylcholine (ACh) acts on two main types of receptors which are nicotinic receptors (NRs) and muscarinic receptors (MRs). NRs induce T cell anergy with impairment of antigen-mediated signal transduction. Nicotine through activation of T cell NRs inhibits the expression and release of the pro-inflammatory cytokines. NRs play important anti-inflammatory effects while MRs promote inflammation by inducing the release of pro-inflammatory cytokines. SARS-CoV-2 infection can affect the morphological and functional stability of CS through the disruption of cholinergic receptors. SARS-CoV-2 spike protein is similar to neurotoxins, which can bind to nicotinic acetylcholine receptors (nAChR) in the ANS and brain. Therefore, cholinergic receptors mainly nAChR and related cholinergic agonists may affect the pathogenesis of SARS-CoV-2 infection. Cholinergic dysfunction in COVID-19 is due to dysregulation of nAChR by SARS-CoV-2 promoting the central sympathetic drive with the development of the sympathetic storm. As well, nAChR activators through interaction with diverse signaling pathways can reduce the risk of inflammatory disorders in COVID-19. In addition, nAChR activators may mitigate endothelial dysfunction (ED), oxidative stress (OS), and associated coagulopathy in COVID-19. Similarly, nAChR activators may improve OS, inflammatory changes, and cytokine storm in COVID-19. Therefore, nAChR activators like varenicline in virtue of its anti-inflammatory and anti-oxidant effects with direct anti-SARS-CoV-2 effect could be effective in the management of COVID-19.

Long COVID could become a widespread post-pandemic disease? A debate on the organs most affected

Long COVID is an emerging problem in the current health care scenario. It is a syndrome with common symptoms of shortness of breath, fatigue, cognitive dysfunction, and other conditions that have a high impact on daily life. They are fluctuating or relapsing states that occur in patients with a history of SARS-CoV-2 infection for at least 2 months. They are usually conditions that at 3 months after onset cannot be explained by an alternative diagnosis. Currently very little is known about this syndrome. A thorough review of the literature highlights that the cause is attributable to deposits of tau protein. Massive phosphorylation of tau protein in response to SARS-CoV-2 infection occurred in brain samples from autopsies of people previously affected with COVID-19. The neurological disorders resulting from this clinical condition are termed tauopathies and can give different pathological symptoms depending on the involved anatomical region of the brain. Peripheral small-fiber neuropathies are also evident among patients with Long COVID leading to fatigue, which is the main symptom of this syndrome. Certainly more research studies could confirm the association between tau protein and Long COVID by defining the main role of tau protein as a biomarker for the diagnosis of this syndrome that is widespread in the post-pandemic period.

Heparin, Heparan Sulphate and Sepsis: Potential New Options for Treatment

Sepsis is a life-threatening hyperreaction to infection in which excessive inflammatory and immune responses cause damage to host tissues and organs. The glycosaminoglycan heparan sulphate (HS) is a major component of the cell surface glycocalyx. Cell surface HS modulates several of the mechanisms involved in sepsis such as pathogen interactions with the host cell and neutrophil recruitment and is a target for the pro-inflammatory enzyme heparanase. Heparin, a close structural relative of HS, is used in medicine as a powerful anticoagulant and antithrombotic. Many studies have shown that heparin can influence the course of sepsis-related processes as a result of its structural similarity to HS, including its strong negative charge. The anticoagulant activity of heparin, however, limits its potential in treatment of inflammatory conditions by introducing the risk of bleeding and other adverse side-effects. As the anticoagulant potency of heparin is largely determined by a single well-defined structural feature, it has been possible to develop heparin derivatives and mimetic compounds with reduced anticoagulant activity. Such heparin mimetics may have potential for use as therapeutic agents in the context of sepsis.

Prior COVID-19 infection may increase risk for developing endothelial dysfunction following hematopoietic cell transplantation

Endothelial dysfunction underlies many of the major complications following hematopoietic cell transplantation (HCT), including transplant-associated thrombotic microangiopathy (TA-TMA), veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), and engraftment syndrome (ES). Emerging evidence similarly implicates endothelitis and microangiopathy in severe COVID-19-related multi-system organ dysfunction. Given the overlap in these two illness states, we hypothesize that prior COVID-19 infection may increase risk for HCT-related endotheliopathies. This retrospective, multicenter study included patients aged 0-25 years who underwent autologous or allogeneic HCT for any indication between January 1, 2020 and September 21, 2021, with close attention to those infected with COVID-19 in either the six months prior to transplant or twelve months following transplant. Incidences of TA-TMA, VOD/SOS, and ES were compared among patients with COVID-19 infection pre-HCT and post-HCT, as well as with historical controls who were never infected with SARS-CoV-2. Those who underwent HCT following COVID-19 infection displayed significantly increased rates of TA-TMA compared to those who were never infected. Additionally, our data suggests a similar trend for increased VOD/SOS and ES rates, although this did not reach statistical significance. Therefore, a history of COVID-19 infection prior to undergoing HCT may be a nonmodifiable risk factor for endothelial-related complications following HCT. Further studies are warranted to better clarify this relationship among larger cohorts and in the era of the Omicron SARS-CoV-2 variants.

Efficacy and safety of two heparin regimens for prevention of venous thromboembolism in hospitalized patients with COVID-19: a meta-analysis

Venous thromboembolism (VTE) is common in patients with coronavirus disease-2019 (COVID-19). The optimal heparin regimen remains unknown and should balance thromboembolic and bleeding risks. The aim of this study was to evaluate the efficacy and safety of standard or higher heparin regimens for the prevention of VTE in patients hospitalized due to COVID-19. We performed a systematic literature search; studies reporting on hospitalized patients with COVID-19 who received standard heparin prophylaxis vs. high (intermediate or therapeutic) heparin regimens were included if outcome events were reported by treatment group and more than 10 patients were included. Primary study outcome was in-hospital VTE. Secondary study outcomes were major bleeding (MB), all-cause death, fatal bleeding and fatal pulmonary embolism. Overall, 33 studies (11,387 patients) were included. Venous thromboembolic events occurred in 5.2% and in 8.2% of patients who received heparin prophylaxis with at high-dose or standard-dose, respectively (RR 0.71, 95% CI 0.55-0.90, I2 48.8%). MB was significantly higher in patients who received high- compared to the standard-dose (4.2% vs 2.2%, RR 1.94, 95% CI 1.47-2.56, I2 18.1%). Sub-analyses showed a slight benefit associated with high-dose heparin in patients admitted to non-intensive care unit (ICU) but not in those to ICU. No significant differences were observed for mortality outcomes. Heparin prophylaxis at high-dose reduces the risk of VTE, but increased the risk of MB compared to the standard-dose. No clinical benefit for heparin high-dose was observed for ICU setting, but its role in the non-ICU deserves further evaluation. PROSPERO registration number: CRD42021252550.

Clinical assessment of endothelial function in convalescent COVID-19 patients: a meta-analysis with meta-regressions

BACKGROUND

Endothelial dysfunction has been proposed to play a key role in the pathogenesis of coronavirus disease 2019 (COVID-19) and its post-acute sequelae. Flow-mediated dilation (FMD) is recognized as an accurate clinical method to assess endothelial function. Thus, we performed a meta-analysis of the studies evaluating FMD in convalescent COVID-19 patients and controls with no history of COVID-19.

METHODS

A systematic literature search was conducted in the main scientific databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Using the random effects method, differences between cases and controls were expressed as mean difference (MD) with 95% confidence intervals (95% CI). The protocol was registered on PROSPERO with reference number CRD42021289684.

RESULTS

Twelve studies were included in the final analysis. A total of 644 convalescent COVID-19 patients showed significantly lower FMD values as compared to 662 controls (MD: -2.31%; 95% CI: -3.19, -1.44; p < 0.0001). Similar results were obtained in the sensitivity analysis of the studies that involved participants in either group with no cardiovascular risk factors or history of coronary artery disease (MD: -1.73%; 95% CI: -3.04, -0.41; p = 0.010). Interestingly, when considering studies separately based on enrolment within or after 3 months of symptom onset, results were further confirmed in both short- (MD: -2.20%; 95% CI: -3.35, -1.05; p < 0.0001) and long-term follow-up (MD: -2.53%; 95% CI: -4.19, -0.86; p = 0.003). Meta-regression models showed that an increasing prevalence of post-acute sequelae of COVID-19 was linked to a higher difference in FMD between cases and controls (Z-score: -2.09; p = 0.037).

CONCLUSIONS

Impaired endothelial function can be documented in convalescent COVID-19 patients, especially when residual clinical manifestations persist. Targeting endothelial dysfunction through pharmacological and rehabilitation strategies may represent an attractive therapeutic option.Key messagesThe mechanisms underlying the post-acute sequelae of coronavirus disease 2019 (COVID-19) have not been fully elucidated.Impaired endothelial function can be documented in convalescent COVID-19 patients for up to 1 year after infection, especially when residual clinical manifestations persist.Targeting endothelial dysfunction may represent an attractive therapeutic option in the post-acute phase of COVID-19.

3D Lung Tissue Models for Studies on SARS-CoV-2 Pathophysiology and Therapeutics

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing the coronavirus disease 2019 (COVID-19), has provoked more than six million deaths worldwide and continues to pose a major threat to global health. Enormous efforts have been made by researchers around the world to elucidate COVID-19 pathophysiology, design efficacious therapy and develop new vaccines to control the pandemic. To this end, experimental models are essential. While animal models and conventional cell cultures have been widely utilized during these research endeavors, they often do not adequately reflect the human responses to SARS-CoV-2 infection. Therefore, models that emulate with high fidelity the SARS-CoV-2 infection in human organs are needed for discovering new antiviral drugs and vaccines against COVID-19. Three-dimensional (3D) cell cultures, such as lung organoids and bioengineered organs-on-chips, are emerging as crucial tools for research on respiratory diseases. The lung airway, small airway and alveolus organ chips have been successfully used for studies on lung response to infection by various pathogens, including corona and influenza A viruses. In this review, we provide an overview of these new tools and their use in studies on COVID-19 pathogenesis and drug testing. We also discuss the limitations of the existing models and indicate some improvements for their use in research against COVID-19 as well as future emerging epidemics.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia–reperfusion (I–R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I–R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.

Mid-Regional Pro-Adrenomedullin as a Prognostic Factor for Severe COVID-19 ARDS

Mid-regional proadrenomedullin (MR-proADM) protects against endothelial permeability and has been associated with prognosis in bacterial sepsis. As endothelial dysfunction is central in the pathophysiology of severe SARS-CoV-2 infection, we sought to evaluate MR-proADM both as a prognostic biomarker and as a marker of bacterial superinfection. Consecutive patients admitted to the ICU for severe SARS-CoV-2 pneumonia were prospectively included and serum was bio-banked on days 1, 3, and 7. MR-proADM levels were measured blindly from clinical outcomes in batches at the end of follow-up. Among the 135 patients included between April 2020 and May 2021, 46 (34.1%) had died at day 60. MR-proADM levels on days 1, 3, and 7 were significantly higher in day-60 non-survivors. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve (0.744, p < 0.001) of day-1 MR-proADM compared favorably with the AUC ROC curve of day-1 procalcitonin (0.691, p < 0.001). Serial MR-proADM measurements on days 3 and 7 may add prognostic information. After adjusting for CRP, LDH, and lymphocyte values, day-1 MR-proADM remained significantly associated with day-60 mortality. MR-proADM concentrations were significantly higher in patients with respiratory superinfections (on days 3 and 7) and bloodstream infections (on days 1, 3, and 7) than in patients without infection. Our results suggest that MR-proADM is a good predictor of outcome in severe SARS-CoV-2 infection and could be a useful tool to assess bacterial superinfection in COVID-19 patients.

Defibrotide Therapy for SARS-CoV-2 ARDS

BACKGROUND

SARS-CoV-2-related ARDS is associated with endothelial dysfunction and profound dysregulation of the thrombotic-fibrinolytic pathway. Defibrotide is a polyanionic compound with fibrinolytic, antithrombotic, and antiinflammatory properties.

RESEARCH QUESTION

What is the safety and tolerability of defibrotide in patients with severe SARS-CoV-2 infections?

STUDY DESIGN AND METHODS

We report a prospective, open-label, single-center safety trial of defibrotide for the management of SARS-CoV-2-related ARDS. Eligible participants were 18 years of age or older with clinical and radiographic signs of ARDS, no signs of active bleeding, a serum D-dimer of more than twice upper limit of normal, and positive polymerase chain reaction-based results for SARS-CoV-2. Defibrotide (6.25 mg/kg/dose IV q6h) was administered for a planned 7-day course, with serum D-dimer levels and respiratory function monitored daily during therapy.

RESULTS

Twelve patients (median age, 63 years) were treated, with 10 patients receiving mechanical ventilation and 6 receiving vasopressor support at study entry. The median D-dimer was 3.25 μg/ml (range, 1.33-12.3) at study entry. The median duration of therapy was 7 days. No hemorrhagic or thrombotic complications occurred during therapy. No other adverse events attributable to defibrotide were noted. Four patients met the day 7 pulmonary response parameter, all four showing a decrease in serum D-dimer levels within the initial 72 h of defibrotide therapy. Three patients died of progressive pulmonary disease 11, 17, and 34 days after study entry. Nine patients (75%) remain alive 64 to 174 days after initiation of defibrotide. Day 30 all-cause mortality was 17% (95% CI, 0%-35%). All patients with a baseline Pao₂ to Fio₂ ratio of ≥ 125 mm Hg survived, whereas the three patients with a baseline Pao₂ to Fio₂ ratio of < 125 mm Hg died.

INTERPRETATION

The use of defibrotide for management of SARS-CoV-2-related ARDS proved safe and tolerable. No hemorrhagic or thrombotic complications were reported during therapy, with promising outcomes in a patient population with a historically high mortality rate.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT04530604; URL: www.

CLINICALTRIALS

gov.

COVID-19 presenting with persistent hiccup and myocardial infarction in a peritoneal dialysis patient: A case report

BACKGROUND

Persistent hiccups, lasting more than 48 h, have been described as an atypical presentation of coronavirus disease 19 (COVID-19) in the general population. To the best of our knowledge, this is the first report of persistent hiccups and non-ST elevation myocardial injury (NSTEMI) as an atypical presentation of COVID-19 in a peritoneal dialysis (PD) patient.

CASE SUMMARY

A 70-year old man, who had been on PD for 3 years with a history of ischemic heart failure and reduced ejection fraction, presented for a scheduled radionuclide myocardial scan. Upon arrival, he complained of anorexia, nausea for 5 d, and unremitting hiccups for the previous 48 h. Clinical and laboratory examinations revealed an NSTEMI plus a positive nasopharyngeal reverse transcriptase polymerase chain reaction testing for severe acute respiratory syndrome coronavirus 2. COVID-19 lung involvement was mild and was resolved without specific treatment. Myocardial injury was managed by coronary catheterization and stenting, while hiccups responded only to baclofen per os.

CONCLUSION

Persistent hiccups and NSTEMI can be atypical presentations of COVID-19 in peritoneal dialysis patients, which may be due to involvement of the central nervous system and myocardial injuries.

Endothelin-1 is increased in the plasma of patients hospitalised with Covid-19

Virus induced endothelial dysregulation is a well-recognised feature of severe Covid-19 infection. Endothelin-1 (ET-1) is the most highly expressed peptide in endothelial cells and a potent vasoconstrictor, thus representing a potential therapeutic target. ET-1 plasma levels were measured in a cohort of 194 Covid-19 patients stratified according to the clinical severity of their illness. Hospitalised patients, including those who died and those developing acute myocardial or kidney injury, had significantly elevated ET-1 plasma levels during the acute phase of infection. The results support the hypothesis that endothelin receptor antagonists may provide clinical benefit for certain Covid-19 patients.

Cardiopulmonary Exercise Performance and Endothelial Function in Convalescent COVID-19 Patients

Background: Endothelial dysfunction has been proposed as the common pathogenic background of most manifestations of coronavirus disease 2019 (COVID-19). Among these, some authors also reported an impaired exercise response during cardiopulmonary exercise testing (CPET). We aimed to explore the potential association between endothelial dysfunction and the reduced CPET performance in COVID-19 survivors. Methods: 36 consecutive COVID-19 survivors underwent symptom-limited incremental CPET and assessment of endothelium-dependent flow-mediate dilation (FMD) according to standardized protocols. Results: A significantly higher FMD was documented in patients with a preserved, as compared to those with a reduced, exercise capacity (4.11% ± 2.08 vs. 2.54% ± 1.85, p = 0.048), confirmed in a multivariate analysis (β = 0.899, p = 0.038). In the overall study population, FMD values showed a significant Pearson’s correlation with two primary CPET parameters, namely ventilation/carbon dioxide production (VE/VCO₂) slope (r = −0.371, p = 0.026) and end-tidal carbon dioxide tension (P_ETCO₂) at peak (r = 0.439, p = 0.007). In multiple linear regressions, FMD was the only independent predictor of VE/VCO₂ slope (β = −1.308, p = 0.029) and peak P_ETCO₂ values (β = 0.779, p = 0.021). Accordingly, when stratifying our study population based on their ventilatory efficiency, patients with a ventilatory class III-IV (VE/VCO₂ slope ≥ 36) exhibited significantly lower FMD values as compared to those with a ventilatory class I-II. Conclusions: The alteration of endothelial barrier properties in systemic and pulmonary circulation may represent a key pathogenic mechanism of the reduced CPET performance in COVID-19 survivors. Personalized pharmacological and rehabilitation strategies targeting endothelial function may represent an attractive therapeutic option.

Clinicopathologic characteristics of severe COVID-19 patients in Mexico City: A post-mortem analysis using a minimally invasive autopsy approach

OBJECTIVE

Describe the histological findings of minimally ultrasound-guided invasive autopsies in deceased patients with severe SARS-CoV-2 and compare the diagnostic yield with open autopsies.

DESIGN

Observational post-mortem cohort study. Minimally invasive ultrasound-guided autopsies were performed in fourteen deceased patients with a confirmed diagnosis of SARS-CoV-2 pneumonia. Histological and clinical findings of lung, kidney, and liver tissue are described and contrasted with those previously reported in the literature.

SETTING

Single-center COVID-19 reference center in Mexico City.

RESULTS

Fourteen minimally invasive autopsies revealed a gross correlation with open autopsies reports: 1) Lung histology was characterized mainly by early diffuse alveolar damage (12/13). Despite low lung compliances and prolonged mechanical ventilation, the fibrotic phase was rarely observed (2/13). 2) Kidney histopathology demonstrated acute tubular injury (12/13), interstitial nephritis (11/13), and glomerulitis (11/13) as the predominant features 3) Liver histology was characterized by neutrophilic inflammation in all of the cases, as well as hepatic necrosis (8/14) despite minimal alterations in liver function testing. Hepatic steatosis was observed in most cases (12/14). SARS-CoV-2 positivity was widely observed throughout the immunohistochemical analysis. However, endothelitis and micro thrombosis, two of the hallmark features of the disease, were not observed.

CONCLUSION

Our data represents the largest minimally invasive, ultrasound-guided autopsy report. We demonstrate a gross histological correlation with large open autopsy cohorts. However, this approach might overlook major histologic features of the disease, such as endothelitis and micro-thrombosis. Whether this represents sampling bias is unclear.

Vascular endotheliitis associated with infections: Its pathogenetic role and therapeutic implication

Vascular endothelial cells are major participants in and regulators of immune responses and inflammation. Vascular endotheliitis is regarded as a host immune-inflammatory response of the endothelium forming the inner surface of blood vessels in association with a direct consequence of infectious pathogen invasion. Vascular endotheliitis and consequent endothelial dysfunction can be a principle determinant of microvascular failure, which would favor impaired perfusion, tissue hypoxia, and subsequent organ failure. Emerging evidence suggests the role of vascular endotheliitis in the pathogenesis of coronavirus disease 2019 (COVID-19) and its related complications. Thus, once initiated, vascular endotheliitis and resultant cytokine storm cause systemic hyperinflammation and a thrombotic phenomenon in COVID-19, leading to acute respiratory distress syndrome and widespread organ damage. Vascular endotheliitis also appears to be a contributory factor to vasculopathy and coagulopathy in sepsis that is defined as life-threatening organ dysfunction due to a dysregulated response of the host to infection. Therefore, protecting endothelial cells and reversing vascular endotheliitis may be a leading therapeutic goal for these diseases associated with vascular endotheliitis. In this review, we outline the etiological and pathogenic importance of vascular endotheliitis in infection-related inflammatory diseases, including COVID-19, and possible mechanisms leading to vascular endotheliitis. We also discuss pharmacological agents which may be now considered as potential endotheliitis-based treatment modalities for those diseases.

Insights into the immune responses of SARS-CoV-2 in relation to COVID-19 vaccines

The three types of approved coronavirus disease 2019 (COVID-19) vaccines that have been emergency-use listed (EUL) by the World Health Organization are mRNA vaccines, adenovirus-vectored vaccines, and inactivated vaccines. Canonical vaccine developments usually take years or decades to be completed to commercialization; however, the EUL vaccines being used in the current situation comprise several COVID-19 vaccine candidates applied in studies and clinical settings across the world. The extraordinary circumstances of the COVID-19 pandemic have necessitated the emergency authorization of these EUL vaccines, which have been rapidly developed. Although the benefits of the EUL vaccines outweigh their adverse effects, there have been reports of rare but fatal cases directly associated with COVID-19 vaccinations. Thus, a reassessment of the immunological rationale underlying EUL vaccines in relation to COVID-19 caused by SARSCOV-2 virus infection is now required. In this review, we discuss the manifestations of COVID-19, immunologically projected effects of EUL vaccines, reported immune responses, informed issues related to COVID-19 vaccination, and the potential strategies for future vaccine use against antigenic variants.

An Update on the Status of Vaccine Development for SARS-CoV-2 Including Variants. Practical Considerations for COVID-19 Special Populations

The progress in the development of various vaccine platforms against SARS-CoV-2 have been rather remarkable owing to advancement in molecular and biologic sciences. Most of the current vaccines and those in development focus on targeting the viral spike proteins by generating antibodies of varying spectrum. These vaccines represent a variety of platforms including whole virus vaccines, viral vector vaccines, nucleic acid vaccines representing RNA, DNA, and their hybrid forms.The therapeutic efficacy of these vaccines varies owing to their pharmacodynamic individualities. COVID-19 variants are capable of inducing different pathologic responses and some of which may be resistant to antibodies generated by current vaccines. The current clinical use of these vaccines has been through emergency use authorization until recently. Moreover, the efficacy and safety of these vaccines have been tested in substantial numbers of individuals but studies in special populations that better reflect the global population are pending results. These specialized populations include young children, immunocompromised patients, pregnant individuals, and other specialized groups. Combination approaches, molecularly modified vaccination approaches, and vaccines conferring longer periods of immunity are being currently being investigated, as well as pharmacovigilance studies.The continual transformation of SARS-CoV-2 and its variants are of concern along with the breakthrough infections. These considerations pose new challenges for the development of vaccination platforms. For this purpose, booster doses, combination vaccine approaches, and other modalities are being discussed. This review provides an updated account of currently available vaccines and those in advanced development with reference to their composition and mechanisms of action.A discussion on the use of vaccines in special populations including immunocompromised patients, pregnant women and other specialized populations are also included.

Opposing roles for sMAdCAM and IL‐15 in COVID‐19 associated cellular immune pathology

Immune cell dysregulation and lymphopenia characterize COVID‐19 pathology in moderate to severe disease. While underlying inflammatory factors have been extensively studied, homeostatic and mucosal migratory signatures remain largely unexplored as causative factors. In this study, we evaluated the association of circulating IL‐6, soluble mucosal addressin cell adhesion molecule (sMAdCAM), and IL‐15 with cellular dysfunction characterizing mild and hypoxemic stages of COVID‐19. A cohort of SARS‐CoV‐2 infected individuals (n = 130) at various stages of disease progression together with healthy controls (n = 16) were recruited from COVID Care Centres (CCCs) across Mumbai, India. Multiparametric flow cytometry was used to perform in‐depth immune subset characterization and to measure plasma IL‐6 levels. sMAdCAM, IL‐15 levels were quantified using ELISA. Distinct depletion profiles, with relative sparing of CD8 effector memory and CD4+ regulatory T cells, were observed in hypoxemic disease within the lymphocyte compartment. An apparent increase in the frequency of intermediate monocytes characterized both mild as well as hypoxemic disease. IL‐6 levels inversely correlated with those of sMAdCAM and both markers showed converse associations with observed lympho‐depletion suggesting opposing roles in pathogenesis. Interestingly, IL‐15, a key cytokine involved in lymphocyte activation and homeostasis, was detected in symptomatic individuals but not in healthy controls or asymptomatic cases. Further, plasma IL‐15 levels negatively correlated with T, B, and NK count suggesting a compensatory production of this cytokine in response to the profound lymphopenia. Finally, higher levels of plasma IL‐15 and IL‐6, but not sMAdCAM, were associated with a longer duration of hospitalization.

Endothelial Dysfunction in Covid-19

COVID-19 is an evolving systemic inflammatory pandemic disease, predominantly affecting the respiratory system. Associated cardiovascular comorbid conditions result in severe to critical illness with mortality up to 14.8 % in octogenarians. The role of endothelial dysfunction in its pathogenesis has been proposed with laboratory and autopsy data, though initially it was thought of as only acute respiratory distress syndrome (ARDS). The current study on endothelial dysfunction in SARS CoV-2 infection highlights its pathophysiology through the effects of direct viral-induced endothelial injury, uncontrolled immune & inflammatory response, imbalanced coagulation homeostasis, and their interactions resulting in a vicious cycle aggravating the disease process. This review may provide further light on proper laboratory tests and therapeutic implications needed for better management of patients. The main objective of the study is to understand the pathophysiology of COVID-19 with respect to the role of endothelium so that more additional relevant treatment may be incorporated in the management protocol.

Effects of Human Nucleolus Upon Guest Viral-Life, Focusing in COVID-19 Infection: A Mini- Review

The nucleolus is a subcellular membrane-less structure of eukaryotic cells. In 1965, in a world's southern summer summit in Uruguay, the role of the nucleolus as the site of ribosome synthesis, biogenesis, and processing of tRNA was conclusively established. Today, accumulating evidence confirm the multiple functions of the nucleolus, including tRNA precursor processing, cell stress sensing, as well as being influential in gene silencing, senescence, lifespan, DNA damage response (DDR), and cell cycle regulation. Therefore, nucleolopathy is observed in various human diseases. Modern advances have provided fundamental insights concerning how and why the nucleolus is targeted by different pathogenic organisms. Viruses are major organisms that disrupt the normal function of the nucleus and produce nucleoli proteins for facilitating the replication of viruses causing viral infections. In this review, we focus on the possible role of nucleoli upon coronavirus infections, particularly in coronavirus disease 2019.

Use of novel antithrombotic agents for COVID-19: Systematic summary of ongoing randomized controlled trials

BACKGROUND

Coronavirus disease 2019 (COVID-19) is associated with macro- and micro-thromboses, which are triggered by endothelial cell activation, coagulopathy, and uncontrolled inflammatory response. Conventional antithrombotic agents are under assessment in dozens of randomized controlled trials (RCTs) in patients with COVID-19, with preliminary results not demonstrating benefit in several studies.

OBJECTIVES

Given the possibility that more novel agents with antithrombotic effects may have a potential utility for management of patients with COVID-19, we assessed ongoing RCTs including these agents with their potential mechanism of action in this population.

METHODS

We searched clinicaltrials.gov and the World Health Organization International Clinical Trials Registry Platform to identify RCTs of novel antithrombotic agents in patients with COVID-19.

RESULTS

Based on a systematic literature search, 27 RCTs with 10 novel antithrombotic agents (including nafamostat, dociparstat, rNAPc2, and defibrotide) were identified. The results from these trials have not been disseminated yet. The studied drugs in the ongoing or completed RCTs include agents affecting the coagulation cascade, drugs affecting endothelial activation, and mixed acting agents. Their postulated antithrombotic mechanisms of action and their potential impact on patient management are summarized.

CONCLUSION

Some novel antithrombotic agents have pleiotropic anti-inflammatory and antiviral effects, which may help reduce the viral load or fibrosis, and improve oxygenation. Results from ongoing RCTs will elucidate their actual role in the management of patients with COVID-19.

Proof-of-concept trial of an amniotic fluid-derived extracellular vesicle biologic for treating high risk patients with mild-to-moderate acute COVID-19 infection

A pandemic brought on by COVID-19 has created a scalable health crisis. The search to help alleviate COVID-19-related complications through therapeutics has become a necessity. Zofin is an investigational, acellular biologic derived from full-term perinatal amniotic fluid that contains extracellular vesicles. Extracellular nanoparticles as such have been studied for their immunomodulatory benefits via cellular therapeutics and, if applied to COVID-19-related inflammation, could benefit patient outcome. Subjects (n = 8) experiencing mild-to-moderate COVID-19 symptoms were treated with the experimental intervention. Complete blood count, complete metabolic panel, inflammatory biomarkers, and absolute lymphocyte counts were recorded prior to and on days 4, 8, 14, 21, and 30 as markers of disease progression. Additionally, chest x-rays were taken of the patients prior to and on days 8 and 30. Patients experienced no serious adverse events. All COVID-19-associated symptoms resolved or became stable with no indication of disease worsening as found by patient and chest x-ray reports. Inflammatory biomarkers (CRP, IL-6, TNF- α ) and absolute lymphocyte counts improved throughout the study period. Findings from a proof-of-concept, expanded access trial for COVID-19 patients prove the acellular biologic is safe and potentially effective to prevent disease progression in a high-risk COVID-19 population with mild-to-moderate symptoms.

Neurological update: COVID-19

Coronavirus Disease 2019 is predominantly a disorder of the respiratory system, but neurological complications have been recognised since early in the pandemic. The major pathophysiological processes leading to neurological damage in COVID-19 are cerebrovascular disease, immunologically mediated neurological disorders and the detrimental effects of critical illness on the nervous system. It is still unclear whether direct invasion of the nervous system by the Severe Acute Respiratory Syndrome Coronavirus 2 occurs; given the vast numbers of people infected at this point, this uncertainty suggests that nervous system infection is unlikely to represent a significant issue if it occurs at all. In this review, we explore what has been learnt about the neurological complications of COVID-19 over the course of the pandemic, and by which mechanisms these complications most commonly occur.

The role of endotheliitis in COVID-19: Real-world experience of 11 190 patients and literature review for a pathophysiological map to clinical categorisation

OBJECTIVE

COVID-19 may yield a variety of clinical pictures, differing from pneumonitis to Acute Respiratory Distress Syndrome along with vascular damage in the lung tissue, named endotheliitis. To date, no specific treatment strategy was approved for the prevention or treatment of COVID-19 in terms of endotheliitis-related comorbidities. Here, we presented our treatment strategies for 11 190 COVID-19 patients depending on categorisation by the severity of both the respiratory and vascular distress and presented the manifestations of endotheliitis in skin, lung and brain tissues according to the different phases of COVID-19.

METHODS

After a retrospective examination, patients were divided into three groups according to their repercussions of vascular distress, which were represented by radiological, histopathological and clinical findings. We presented the characteristics and courses of seven representative and complicated cases which demonstrate different phases of the disease and discussed the treatment strategies in each group.

RESULTS

Among 11 190 patients, 9294 patients met the criteria for Group A, and 1376 patients were presented to our clinics with Group B characteristics. Among these patients, 1896 individuals (Group B and Group C) were hospitalised. While 1220 inpatients were hospitalised within the first 10 days after the diagnosis, 676 of them were worsened and hospitalised 10 days after their diagnosis. Among hospitalised patients, 520 of them did not respond to group A and B treatments and developed hypoxemic respiratory failure (Group C) and 146 individuals needed ventilator support and were followed in the intensive care unit, and 43 (2.2%) patients died.

CONCLUSION

Distinctive manifestations in each COVID-19 patient, including non-respiratory conditions in the acute phase and the emerging risk of long-lasting complications, suggest that COVID-19 has endotheliitis-centred thrombo-inflammatory pathophysiology. Daily evaluation of clinical, laboratory and radiological findings of patients and deciding appropriate pathophysiological treatment would help to reduce the mortality rate of COVID-19.

Adverse Outcome in Non-Severe COVID-19: Potential Diagnostic Coagulation Tests

COVID-19-associated coagulopathy (CAC) identifies the coagulation changes in coronavirus disease 2019 (COVID-19) and is responsible for thrombosis. CAC has been studied in critical and severe stage COVID-19 disease through tests including the D-Dimer (DD), prothrombin time (PT), thromboplastin partial time (PTT), platelet count, fibrinogen (Fib), and platelet factor 4 (PF4) tests. However, these tests have some limitations. The aim of this study was to identify more accurate warning tests for early recognition of CAC and to prevent its deterioration to disseminated intravascular coagulation (DIC). First, we measured Interleukin-1α (IL-1α) and IL-8, and tissue factor pathway inhibitor (TFPI) as inflammation and endothelial damage markers, respectively. Second, we measured thrombin antithrombin complex (TAT), β-Thromboglobulin (β-TG), and thromboelastometric parameters including clotting time (CT), clot formation time (CFT), clot firmness (MCF), and clot lysis at 30 min (LY-30), as markers of coagulation and platelet activation. This study included 100 non-severe patients with COVID-19 that developed pulmonary embolism (PE) compared to 80 healthy patients. IL-1α and IL-8, and TFPI were higher as well as TAT and β-TG and thromboelastometric parameters, indicating hypercoagulability. If confirmed in other studies, these results could help in predicting the deterioration of non-severe COVID-19 disease, thereby reducing hospitalizations and health costs.

Upregulation of pulmonary tissue factor, loss of thrombomodulin and immunothrombosis in SARS-CoV-2 infection

BACKGROUND

SARS-CoV-2 infection is associated with thrombotic and microvascular complications. The cause of coagulopathy in the disease is incompletely understood.

METHODS

A single-center cross-sectional study including 66 adult COVID-19 patients (40 moderate, 26 severe disease), and 9 controls, performed between 04/2020 and 10/2020. Markers of coagulation, endothelial cell function [angiopoietin-1,-2, P-selectin, von Willebrand Factor Antigen (WF:Ag), von Willebrand Factor Ristocetin Cofactor, ADAMTS13, thrombomodulin, soluble Endothelial cell Protein C Receptor (sEPCR), Tissue Factor Pathway Inhibitor], neutrophil activation (elastase, citrullinated histones) and fibrinolysis (tissue-type plasminogen activator, plasminogen activator inhibitor-1) were evaluated using ELISA. Tissue Factor (TF) was estimated by antithrombin-FVIIa complex (AT/FVIIa) and microparticles-TF (MP-TF). We correlated each marker and determined its association with severity. Expression of pulmonary TF, thrombomodulin and EPCR was determined by immunohistochemistry in 9 autopsies.

FINDINGS

Comorbidities were frequent in both groups, with older age associated with severe disease. All patients were on prophylactic anticoagulants. Three patients (4.5%) developed pulmonary embolism. Mortality was 7.5%. Patients presented with mild alterations in the coagulogram (compensated state). Biomarkers of endothelial cell, neutrophil activation and fibrinolysis were elevated in severe vs moderate disease; AT/FVIIa and MP-TF levels were higher in severe patients. Logistic regression revealed an association of D-dimers, angiopoietin-1, vWF:Ag, thrombomodulin, white blood cells, absolute neutrophil count (ANC) and hemoglobin levels with severity, with ANC and vWF:Ag identified as independent factors. Notably, postmortem specimens demonstrated epithelial expression of TF in the lung of fatal COVID-19 cases with loss of thrombomodulin staining, implying in a shift towards a procoagulant state.

INTERPRETATION

Coagulation dysregulation has multifactorial etiology in SARS-Cov-2 infection. Upregulation of pulmonary TF with loss of thrombomodulin emerge as a potential link to immunothrombosis, and therapeutic targets in the disease.

FUNDING

John Hopkins University School of Medicine.

Lifestyle-mediated nitric oxide boost to prevent SARS-CoV-2 infection: A perspective

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide and has seriously threatened public health by causing significant morbidity and mortality. Patients with coronavirus disease (COVID-19) with preexisting endothelial dysfunction caused by aging, diabetes, hypertension, and obesity are at high risk for life-threatening thromboembolic complications. This suggests a possibility that reduced endothelial nitric oxide (NO) production and NO bioavailability could be a common underlying pathology for the progression of COVID-19. Increasingly, evidence from experimental and clinical studies of SARS-CoV-2 infection shows that NO inhibits the pathogenesis of COVID-19, including virus entry into host cells, viral replication, host immune response, and subsequent thromboembolic complications. Restoring NO bioavailability may have the potential to be a preventive or early-treatment option for COVID-19. This review aims to provide in-depth discussion of NO bioavailability to prevent SARS-CoV-2 infection, particularly by focusing on lifestyle factors such as nitrate-rich diets, physical exercise, and nasal breathing, which could be easily performed on a daily basis to boost NO bioavailability.

Persistent Endothelial Dysfunction in Post-Acute COVID-19 Syndrome: A Case-Control Study

Background: Endothelial dysfunction has a key role in the pathogenesis of coronavirus disease 2019 (COVID-19) and its disabling complications. We designed a case-control study to assess the alterations of endothelium-dependent flow-mediated dilation (FMD) among convalescent COVID-19 patients. Methods: COVID-19 patients referred to a Pulmonary Rehabilitation Unit within 2 months from swab test negativization were consecutively evaluated for inclusion and compared to controls matched for age, gender, and cardiovascular risk factors. Results: A total of 133 convalescent COVID-19 patients (81.2% males, mean age 61.6 years) and 133 matched controls (80.5% males, mean age 60.4 years) were included. A significantly lower FMD was documented in convalescent COVID-19 patients as compared to controls (3.2% ± 2.6 vs. 6.4% ± 4.1 p < 0.001), confirmed when stratifying the study population according to age and major clinical variables. Among cases, females exhibited significantly higher FMD values as compared to males (6.1% ± 2.9 vs. 2.5% ± 1.9, p < 0.001). Thus, no significant difference was observed between cases and controls in the subgroup analysis on females (6.1% ± 2.9 vs. 5.3% ± 3.4, p = 0.362). Among convalescent COVID-19 patients, FMD showed a direct correlation with arterial oxygen tension (rho = 0.247, p = 0.004), forced expiratory volume in 1 s (rho = 0.436, p < 0.001), forced vital capacity (rho = 0.406, p < 0.001), and diffusing capacity for carbon monoxide (rho = 0.280, p = 0.008). Overall, after adjusting for major confounders, a recent COVID-19 was a major and independent predictor of FMD values (β = −0.427, p < 0.001). Conclusions: Post-acute COVID-19 syndrome is associated with a persistent and sex-biased endothelial dysfunction, directly correlated with the severity of pulmonary impairment.

Connecting the Dots: Interplay of Pathogenic Mechanisms between COVID-19 Disease and Mucormycosis

Coronavirus disease (COVID-19)-associated mucormycosis (CAM) is an emerging threat globally, especially in India. More than 40,000 CAM cases have been reported in India. The emergence of CAM cases in India has been attributed to environmental, host, and iatrogenic factors. Mucorales spore burden has been reported globally; however, their presence is higher in tropical countries such as India, contributing to the emergence of CAM. Before the COVID-19 pandemic, patients with diabetes mellitus, haematological malignancies, solid organ transplants, corticosteroid therapy and neutropenia were more prone to mucormycosis, whereas in COVID-19 patients, virus-induced endothelial dysfunction, hyperglycaemia, and immune dysfunction following corticosteroid use increase the risk of acquiring mucormycosis. The interaction of Mucorales spores with the epithelial cells, followed by endothelial invasion, is a crucial step in the pathogenesis of mucormycosis. Endothelial damage and increased endothelial receptor expression induced by COVID-19 infection may predispose patients to CAM. COVID-19 infection may directly induce hyperglycaemia by damaging beta cells of the pancreas or by corticosteroid therapy, which may contribute to CAM pathogenesis. Iron acquisition from the host, especially in diabetic ketoacidosis (DKA) or deferoxamine therapy, is an important virulence trait of Mucorales. Similarly, the hyperferritinaemia caused by COVID-19 may act as a source of iron for Mucorales growth and invasion. In addition, corticosteroid treatment reduces or abolishes the innate immune functions of phagocytic cells contributing to the pathogenesis of CAM. This review aims to discuss primarily the host and iatrogenic factors shared between COVID-19 and mucormycosis that could explain the emergence of CAM.

Clinical Assessment of Endothelial Function in Convalescent COVID-19 Patients Undergoing Multidisciplinary Pulmonary Rehabilitation

Background: Growing evidence points to a key role of endothelial dysfunction in the pathogenesis of COVID-19. In this study, we evaluated changes in endothelium-dependent flow-mediated dilation (FMD) in a cohort of convalescent COVID-19 patients undergoing pulmonary rehabilitation (PR). Methods: After swab test negativization, convalescent COVID-19 patients referring to a post-acute care facility for PR were consecutively screened for inclusion. Study procedures were performed at the time of hospitalization and discharge. Results: We enrolled 82 convalescent COVID-19 patients (85.4% males, mean age 60.4 years). After PR, a significant improvement in most pulmonary function tests and exercise capacity was documented. FMD changed from 2.48% ± 2.01 to 4.24% ± 2.81 (p < 0.001), corresponding to a 70.9% increase. Significantly higher changes in FMD were found in patients without a history of vascular events as compared to those with (+2.04% ± 2.30 vs. +0.61% ± 1.83, p = 0.013). Values of forced expiratory volume in 1 s (FEV₁%), forced vital capacity (FVC%) and diffusion capacity for carbon monoxide (DLCO%) significantly and directly correlated with FMD both at baseline and after PR. Patients with normal FEV₁% (≥80% predicted) during the overall study period or those normalizing FEV₁% after PR showed a more significant FMD change as compared to patients with persistently impaired FEV₁% (<80% predicted) (p for trend = 0.029). This finding was confirmed in a multivariate analysis. Conclusions: Clinically evaluated endothelial function improves after PR in convalescent COVID-19 patients. A direct and persistent association between the severity of pulmonary and vascular disease can be hypothesized. Endothelial function testing may be useful in the follow-up of convalescent COVID-19 patients.

An Update on the Pathogenesis of COVID-19 and the Reportedly Rare Thrombotic Events Following Vaccination

Today the coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has become a global health problem. After more than a year with the pandemic, although our knowledge has progressed on COVID-19, there are still many unknowns in virological, pathophysiological and immunological aspects. It is obvious that the most efficient solution to end this pandemic are safe and efficient vaccines. This manuscript summarizes the pathophysiological and thrombotic features of COVID-19 and the safety and efficacy of currently approved COVID-19 vaccines with an aim to clarify the recent concerns of thromboembolic events after COVID-19 vaccination. The influx of newer information is rapid, requiring periodic updates and objective assessment of the data on the pathogenesis of COVID-19 variants and the safety and efficacy of currently available vaccines.