Vasculopathy and Coagulopathy Associated with SARS-CoV-2 Infection

Vascular Alterations Following COVID-19 Infection: A Comprehensive Literature Review

SARS-CoV-2, the causative agent of the ongoing COVID-19 pandemic, has revealed a broader impact beyond the respiratory system, predominantly affecting the vascular system with various adverse manifestations. The infection induces endothelial dysfunction and immune system dysregulation, creating an inflammatory and hypercoagulable state. It affects both microvasculature and macrovasculature, leading to thromboembolic events, cardiovascular manifestations, impaired arterial stiffness, cerebrovascular complications, and nephropathy, as well as retinopathy-frequently observed in cases of severe illness. Evidence suggests that SARS-CoV-2 infection may result in persistent effects on the vascular system, identified as long-term COVID-19. This is characterized by prolonged inflammation, endotheliopathy, and an increased risk of vascular complications. Various imaging modalities, histopathological studies, and diagnostic tools such as video capillaroscopy and magnetic resonance imaging have been employed to visualize vascular alterations. This review aims to comprehensively summarize the evidence concerning short and long-term vascular alterations following COVID-19 infection, investigating their impact on patients' prognosis, and providing an overview of preventive strategies to mitigate associated vascular complications.

The Effect of Coronavirus Disease 2019 on the Quality of Associated Care in Patients with Gastric Cancer

Coronavirus is a new virus that has affected human life on a large scale; it has infected millions of people and killed hundreds of thousands of people. In contrast, among cancers, stomach neoplasia is the most common cancer of the upper gastrointestinal (UGI) tract. COVID-19 disease has disrupted the optimal management of patients with cancer. Metastasis, deterioration of the patient's nutritional status, UGI bleeding, and increased surgical complications are all consequences of delayed treatment of patients with gastric cancer. However, there is still insufficient evidence on the immunogenicity of the vaccine and the protection provided by coronavirus vaccines in patients with cancer, especially those with immunodeficiency or those who are treated for certain types of cancers. Also, as part of the prevention and control of COVID-19 disease, nutritional support for patients with gastrointestinal cancer is particularly important, and the psychological and physiological limitations caused by the disease duration are hurting the well-being of patients. Therefore, the assessment of the impact of the coronavirus on cancer should be treated as an important issue, and healthcare professionals should be prepared to deal with the long-term effects of the coronavirus disease.

The impact of COVID-19 on clinical outcomes of burn patients

Background

Multiple studies have shown the SARS-CoV-2 virus (COVID-19) to be associated with deleterious outcomes in a wide range of patients. The impact of COVID-19 has not been well investigated among burned patients. We suspect that patients will have worsened respiratory and thrombotic complications, ultimately leading to increased mortality. The objective of this study is to determine the impact a concurrent infection of COVID-19 has on clinical outcomes after a burn injury.

Methods

This is a retrospective, propensity matched, cohort study. We examined a de-identified database of electronic medical records of over 75 million patients across 75 health care associations in the United States for patients treated for thermal burns from 1 January 2020, to 31 July 2021, and those who also were diagnosed with COVID-19 infection within one day before or after injury based on International Classification of Disease, tenth revision (ICD-10) codes. Study participants included adults who were treated for a burn injury during the study period.

Results

We included 736 patients with burn injury and concomitant COVID-19 infection matched to 736 patients with burn injury and no concurrent COVID-19 infection (total 1472 patients, mean age 36.3 ± 24.3). We found no significant increase in mortality observed for patients with concurrent COVID-19 (OR 1.203, 95% CI 0.517-2.803; p = 0.6675). We did observe significant increase in infections (OR 3.537, 95% CI 2.798-4.471; p = 0.0001), thrombotic complications (OR 2.342, 95% CI 1.351-4.058; p = 0.0018), as was the incidence of hypertrophic scarring (OR 3.368, 95% CI 2.326-4.877; p = 0.0001).

Conclusions

We observed that concurrent COVID-19 infection was associated with an increase in infections, thrombosis and hypertrophic scarring but no increase in mortality in our cohort of burn patients.

Epidemiology, pathogenesis, and management of Coronavirus disease 2019-associated stroke

The Coronavirus disease 2019 (COVID-19) epidemic has triggered a huge impact on healthcare, socioeconomics, and other aspects of the world over the past three years. An increasing number of studies have identified a complex relationship between COVID-19 and stroke, although active measures are being implemented to prevent disease transmission. Severe COVID-19 may be associated with an increased risk of stroke and increase the rates of disability and mortality, posing a serious challenge to acute stroke diagnosis, treatment, and care. This review aims to provide an update on the influence of COVID-19 itself or vaccines on stroke, including arterial stroke (ischemic stroke and hemorrhagic stroke) and venous stroke (cerebral venous thrombosis). Additionally, the neurovascular mechanisms involved in SARS-CoV-2 infection and the clinical characteristics of stroke in the COVID-19 setting are presented. Evidence on vaccinations, potential therapeutic approaches, and effective strategies for stroke management has been highlighted.

Guillain-Barre syndrome and pulmonary embolism in an adult female with COVID-19 infection in Ghana: A case report

INTRODUCTION

The coronavirus disease 2019 (COVID-19) pandemic began at the end of 2019 in Wuhan, the capital of Hubei Province, China. This novel coronavirus is classified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Neurological manifestations are commonly associated with moderate to severe COVID-19 infection. Guillain-Barré syndrome (GBS) is a rare immune-mediated postinfectious neuropathy but there has been an increase in the number of cases of GBS associated with COVID-19, supporting the present body of global evidence of the notable association between the 2 conditions. We present the first proven case of GBS and pulmonary embolism associated with COVID-19 infection in Ghana, West Africa.

CASE PRESENTATION

A 60-year-old apparently healthy female presented in August 2020 to the COVID-19 treatment center of the Korle-Bu Teaching Hospital in Accra, Ghana from a referral facility following a week's history of low-grade fever, chills, rhinorrhoea, and generalized flaccid limb weakness. A positive SARS-CoV-2 test result was recorded 3 days after the onset of symptoms and the patient had no known chronic medical condition. Following cerebrospinal fluid analysis, neurophysiological studies and a chest computed tomography pulmonary angiogram, Guillain-Barre syndrome and pulmonary embolism were confirmed. The patient was however managed supportively and then discharged after 12 days on admission, as he made mild improvement in muscular power and function.

CONCLUSION

This case report adds to the body of evidence of the association between GBS and SARS-CoV-2 infection, particularly from West Africa. It further highlights the need to anticipate potential neurological complications of SARS-CoV-2, particularly GBS even in mild respiratory symptoms for prompt diagnosis and initiation of appropriate therapy to improve outcomes and avert long-term deficits.

Pathways of Coagulopathy and Inflammatory Response in SARS-CoV-2 Infection among Type 2 Diabetic Patients

Chronic inflammation and endothelium dysfunction are present in diabetic patients. COVID-19 has a high mortality rate in association with diabetes, partially due to the development of thromboembolic events in the context of coronavirus infection. The purpose of this review is to present the most important underlying pathomechanisms in the development of COVID-19-related coagulopathy in diabetic patients. The methodology consisted of data collection and synthesis from the recent scientific literature by accessing different databases (Cochrane, PubMed, Embase). The main results are the comprehensive and detailed presentation of the very complex interrelations between different factors and pathways involved in the development of arteriopathy and thrombosis in COVID-19-infected diabetic patients. Several genetic and metabolic factors influence the course of COVID-19 within the background of diabetes mellitus. Extensive knowledge of the underlying pathomechanisms of SARS-CoV-2-related vasculopathy and coagulopathy in diabetic subjects contributes to a better understanding of the manifestations in this highly vulnerable group of patients; thus, they can benefit from a modern, more efficient approach regarding diagnostic and therapeutic management.

The Effect of COVID-19 Vaccines on Stroke Outcomes: A Single-Center Study

BACKGROUND

One of the defining narratives of the COVID-19 pandemic has been the acceptance and distribution of vaccine. To compare the outcomes of COVID-19 positive vaccinated and unvaccinated stroke patients.

METHODS

This is a single-center retrospective study of COVID-19-vaccinated and unvaccinated stroke patients between April 2020 and March 2022. All patients presenting with stroke regardless of treatment modalities were included. National Institutes of Health Stroke Scale was used to assess stroke severity. The primary outcome was functional capacity of the patients at discharge.

RESULTS

The study cohort comprised 203 COVID-19 positive stroke patients divided into 139 unvaccinated and 64 fully vaccinated patients. At discharge, the modified Rankin scale score was significantly lower in the vaccinated cohort (3[1-4] vs. 4[2-5], odds ratio = 0.508, P = 0.011). At 3 months of follow-up, the median modified Rankin scale score was comparable between both cohorts.

CONCLUSIONS

Although vaccination did not show any significant difference in stroke patient outcomes on follow-up, vaccines were associated with lower rates of morbidity and mortality at discharge among stroke patients during the pandemic.

SARS-CoV-2 Possible Etiology of Cerebral Venous Thrombosis in a Teenager: Case Report and Review of Literature

Cerebral venous thrombosis in pediatric patient has a varied etiology. The authors present the case of a teenager who, since the debut of SARS-CoV-2 infection, has accused intermittent right side hemicrania, which has become persistent in association with nausea and vomiting since the 5th day of quarantine. She was hospitalized in the 9th day since the debut. Neuroimaging revealed extended venous cerebral thrombosis affecting the right sigmoid sinus, the transverse sinus bilaterally, the confluence of the transverse sinuses and the right internal jugular vein. The evolution was favorable under anticoagulant and symptomatic treatment. Laboratory tests excluded other etiological causes for the cerebral venous thrombosis, thus the authors consider that cerebral thrombosis is a possible complication of SARS-CoV-2 infection in teenagers.

International Controlled Study of Revascularization and Outcomes Following COVID-Positive Mechanical Thrombectomy

Background and purpose

Previous studies suggest that mechanisms and outcomes in patients with COVID‐19‐associated stroke differ from those in patients with non‐COVID‐19‐associated strokes, but there is limited comparative evidence focusing on these populations. The aim of this study, therefore, was to determine if a significant association exists between COVID‐19 status with revascularization and functional outcomes following thrombectomy for large vessel occlusion (LVO), after adjustment for potential confounding factors.

Methods

A cross‐sectional, international multicenter retrospective study was conducted in consecutively admitted COVID‐19 patients with concomitant acute LVO, compared to a control group without COVID‐19. Data collected included age, gender, comorbidities, clinical characteristics, details of the involved vessels, procedural technique, and various outcomes. A multivariable‐adjusted analysis was conducted.

Results

In this cohort of 697 patients with acute LVO, 302 had COVID‐19 while 395 patients did not. There was a significant difference (p < 0.001) in the mean age (in years) and gender of patients, with younger patients and more males in the COVID‐19 group. In terms of favorable revascularization (modified Thrombolysis in Cerebral Infarction [mTICI] grade 3), COVID‐19 was associated with lower odds of complete revascularization (odds ratio 0.33, 95% confidence interval [CI] 0.23–0.48; p < 0.001), which persisted on multivariable modeling with adjustment for other predictors (adjusted odds ratio 0.30, 95% CI 0.12–0.77; p = 0.012). Moreover, endovascular complications, in‐hospital mortality, and length of hospital stay were significantly higher among COVID‐19 patients (p < 0.001).

Conclusion

COVID‐19 was an independent predictor of incomplete revascularization and poor functional outcome in patients with stroke due to LVO. Furthermore, COVID‐19 patients with LVO were more often younger and had higher morbidity/mortality rates.

Neurological effects of COVID-19 in infants and children

Neurological manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in children are becoming increasingly apparent as the coronavirus disease (COVID-19) pandemic continues. While children manifest relatively milder features of the disease, accumulating evidence warrants concern that COVID-19 exacts both acute- and long-term effects on the developing central and peripheral nervous systems. This review focuses on the relatively underinvestigated topic of the effects of SARS-CoV-2 on the brain in infancy and childhood, concluding that clinicians should be attentive to both the acute effects and long-term consequences of COVID-19 from a neurological perspective.

Characteristics of a COVID-19 Cohort With Large Vessel Occlusion: A Multicenter International Study

BACKGROUND

The mechanisms and outcomes in coronavirus disease (COVID-19)-associated stroke are unique from those of non-COVID-19 stroke.

OBJECTIVE

To describe the efficacy and outcomes of acute revascularization of large vessel occlusion (LVO) in the setting of COVID-19 in an international cohort.

METHODS

We conducted an international multicenter retrospective study of consecutively admitted patients with COVID-19 with concomitant acute LVO across 50 comprehensive stroke centers. Our control group constituted historical controls of patients presenting with LVO and receiving a mechanical thrombectomy between January 2018 and December 2020.

RESULTS

The total cohort was 575 patients with acute LVO; 194 patients had COVID-19 while 381 patients did not. Patients in the COVID-19 group were younger (62.5 vs 71.2; P < .001) and lacked vascular risk factors (49, 25.3% vs 54, 14.2%; P = .001). Modified thrombolysis in cerebral infarction 3 revascularization was less common in the COVID-19 group (74, 39.2% vs 252, 67.2%; P < .001). Poor functional outcome at discharge (defined as modified Ranklin Scale 3-6) was more common in the COVID-19 group (150, 79.8% vs 132, 66.7%; P = .004). COVID-19 was independently associated with a lower likelihood of achieving modified thrombolysis in cerebral infarction 3 (odds ratio [OR]: 0.4, 95% CI: 0.2-0.7; P < .001) and unfavorable outcomes (OR: 2.5, 95% CI: 1.4-4.5; P = .002).

CONCLUSION

COVID-19 was an independent predictor of incomplete revascularization and poor outcomes in patients with stroke due to LVO. Patients with COVID-19 with LVO were younger, had fewer cerebrovascular risk factors, and suffered from higher morbidity/mortality rates.

[Anticoagulation in coronavirus disease 2019 (COVID-19): confirmed and controversial aspects]

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with a high risk of microvascular immunothrombosis as well as symptomatic and incidental thromboembolisms, predominantly in the venous system but also in the arterial system. This explains among other things the high cardiovascular morbidity and mortality of the patients. The present state of knowledge on the pathophysiology of immunothrombosis and the strategies of anticoagulation in patients with coronavirus disease 2019 (COVID-19) are summarized and illuminated in this article. According to the current guidelines moderately to severely ill patients who are being treated in hospital should receive thrombosis prophylaxis with low molecular weight or unfractionated heparin or alternatively with fondaparinux, as long as there is no clearly increased risk of bleeding. Apart from the established indications for treatment, an intensified or therapeutic dose prophylaxis should be considered very cautiously in these critically ill patients, also due to the increased bleeding complications. The routine continuation of prophylactic anticoagulation after discharge from hospital is currently not recommended.

Does COVID-19 infection increase the risk of pressure injury in critically ill patients?: A narrative review

ABSTRACT

Patients with severe COVID-19 may have endothelial dysfunction and a hypercoagulable state that can cause skin damage. In the presence of external pressure on the tissues, the local inflammatory process regulated by inflammatory cytokines can increase and prolong itself, contributing to the formation of pressure injury (PI). PI is defined as localized damage to the skin or underlying tissues. It usually occurs as a result of intense and/or prolonged pressure in combination with shear. The aim of the study is to perform a narrative review on the physiological evidence of increased risk in the development of PI in critically ill patients with COVID-19.In patients with severe COVID-19 a pattern of tissue damage consistent with complement-mediated microvascular injury was found in the lungs and skin of critically ill COVID-19 patients, suggesting sustained systemic activation of complement pathways. Theoretically, the same thrombogenic vascular changes related to COVID-19 that occur in the skin also occur in the underlying tissues, making patients less tolerant to the harmful effects of pressure and shear. Unlike the syndromes typical of acute respiratory illnesses and other pathologies that commonly lead to intensive care unit admission, COVID-19 and systemic viral spread show that local and systemic factors overlap. This fact may be justified by current epidemiological data showing that the prevalence of PI among intensive care unit patients with COVID-19 was 3 times higher than in those without COVID-19. This narrative review presents physiological evidence to suggesting an increased risk of developing PI in critically ill patients with COVID-19.

Vitamin D Inhibits IL-6 Pro-Atherothrombotic Effects in Human Endothelial Cells: A Potential Mechanism for Protection against COVID-19 Infection?

Background: Thrombosis with cardiovascular involvement is a crucial complication in COVID-19 infection. COVID-19 infects the host by the angiotensin converting enzyme-2 receptor (ACE2r), which is expressed in endothelial cells too. Thus, COVID-related thrombotic events might be due to endothelial dysfunction. IL-6 is one of the main cytokines involved in the COVID-19 inflammatory storm. Some evidence indicates that Vitamin D (VitD) has a protective role in COVID-19 patients, but the molecular mechanisms involved are still debated. Thus, we investigated the effect of VitD on Tissue Factor and adhesion molecules (CAMs) in IL-6-stimulated endothelial cells (HUVEC). Moreover, we evaluated levels of the ACE2r gene and proteins. Finally, we studied the modulation of NF-kB and STAT3 pathways. Methods: HUVEC cultivated in VitD-enriched medium were stimulated with IL-6 (0.5 ng/mL). The TF gene (RT-PCR), protein (Western blot), surface expression (FACS) and procoagulant activity (FXa generation assay) were measured. Similarly, CAMs soluble values (ELISA) and ACE2r (RT-PCR and Western blot) levels were assessed. NF-kB and STAT3 modulation (Western blot) were also investigated. Results: VitD significantly reduced TF expression at both gene and protein levels as well as TF-procoagulant activity in IL-6-treated HUVEC. Similar effects were observed for CAMs and ACE2r expression. IL-6 modulates these effects by regulating NF-κB and STAT3 pathways. Conclusions: IL-6 induces endothelial dysfunction with TF and CAMs expression via upregulation of ACE2r. VitD prevented these IL-6 deleterious effects. Thus, it might be speculated that this is one of the hypothetical mechanism(s) by which VitD exerts its beneficial effects in COVID-19 infection.

Neurological Aspects of the Sequelae of COVID-19 in Children

It has now been established that neurological and neuropsychiatric disorders persist for prolonged periods in a significant proportion of adult patients who have had COVID-19, though there is much less information about the manifestations of post-COVID syndrome (PCS) in children and adolescents. This review presents data on the features of the course of PCS in young patients, and considers the options for treating these patients. The results of studies on the use of Cortexin for correcting cognitive and emotional disorders are analyzed.

RHINOSINUSITIS IN PATIENTS IN POST-COVID-19 PERIOD: ETIOLOGY, CLINICAL AND MORPHOLOGICAL CHARACTERISTICS

OBJECTIVE

The aim is to identify the etiology, clinical and morphological features of rhinosinusitis in patients in post-COVID-19 period.

PATIENTS AND METHODS

Materials and methods: In the present study, it was carried out the analysis of 11 cases of rhinosinusitis, which developed after COVID-19 infection. The diagnosis of rhi¬nosinusitis was established on the basis of anamnesis, clinical and laboratory examination, specialized instrumental examination (rhinoendoscopy, X-ray, magnetic resonance imaging, spiral and 3D computed tomography). All patients underwent endoscopic sanitation of the nasal cavity, expansion of the maxillary anastomosis, maxillary sinusotomy, sanitation of the maxillary sinuses and removal of pathologically altered tissues. Microbiological examination of the swab from the nasal cavity was carried out in all patients. Histological and morphometric research methods were used during the morphological study of surgical material. The nonparametric Mann-Whitney U test was used to compare the means in the groups.

RESULTS

Results: The conducted comprehensive study made it possible to identify chronic atrophic rhinosinusitis at the stage of exacerbation caused by associations of bacteria and fungi in patients in post-COVID-19 period. Among bacteria, the authors most often noted Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumonia, Streptococcus pneumonia and Enterococcus faecalis. Among fungi, there were Aspergillus, Candida, Mucor and Coccidioides. Fungal infection was characterized by invasion into the mucous membrane of the nose and paranasal sinuses. In patients in post-COVID-19 period the invasive bacterial-fungal chronic atrophic rhinosinusitis at the stage of exacerbation was predominantly bilateral, characterized by the involvement of several or all paranasal sinuses in the process. Patients with such pathology complained of periodic fever, headaches and malaise; nasal congestion and constant difficulty in nasal breathing; yellowish-greenish-reddish discharge from the nasal cavity, sometimes with a fetid odor; discomfort and pain in the area of paranasal sinuses; immobility of the eyeball, hyposmia or anosmia; reduction or complete loss of vision. Frequent risk factors for the development of invasive bacterial-fungal chronic atrophic rhinosinusitis at the stage of exacerbation in patients in post-COVID-19 period were the information about moderate or severe course of this infection in anamnesis; comorbidities (predominantly diabetes mellitus, hypertensive disease and ischemic heart disease).

CONCLUSION

Conclusions: The study conducted by the authors made it possible to identify the etiological, clinical and morphological features, as well as risk factors of rhinosinusitis in patients in post-COVID-19 period. This information will contribute to a better understanding of such pathology by the doctors and improve the diagnostic and treatment process.

Unusual pattern of thrombotic events in young adult non-critically ill patients with COVID-19 may result from an undiagnosed inherited and acquired form of thrombophilia

In 145 previously healthy non-critically ill young adults, coronavirus disease 2019 (COVID-19)-related symptoms, risk factors for thrombosis, coagulation and inflammatory parameters were compared, with 29 patients reporting unusual thrombotic events (UTEs) and 116 not having thrombotic events. The inflammatory indices, coagulation and prothrombotic platelet phenotype (PTPP) were significantly higher in patients with UTEs versus those without. Patients with UTEs were categorised according to detection of thrombophilic genes (TGs), coagulation and inflammatory markers to the non-TG and TG subcohort. A total of 38 UTEs were identified, which included splanchnic vein thrombosis (SVT; 11), stroke (six), cerebral vein thrombosis (five), thrombotic microangiopathy (four), limb ischaemia and inferior vena cava thrombosis (three each), ST-segment elevation myocardial infarction (two), superior vena cava thrombosis (two), upper limb deep venous thrombosis and retinal vein thrombosis, one each. We found a 55% prevalence of TGs mainly heterozygous coagulation factor II, thrombin (FII)-G20210A, Janus kinase 2 (JAK2)-V617F, protein-S, and antithrombin III deficiency with a high (76·9%) prevalence of venous UTEs, multiple vessels thrombosis, and recurrence rate among the TG versus non-TG subcohort. The presence of JAK2-V617F, and FII-G20210A mutations was linked with SVT. Thrombosis in the non-TG subcohort was associated with more haemorrhagic problems, thrombosis progression and a significantly higher level of inflammatory markers, PTPP, mean platelet volume, von Willebrand factor, and factor VIII, which remained high for up to 6 months, as well as elevated D-dimer. Acquired and inherited thrombophilia with endotheliopathy appeared to be a relevant mechanism to explain the occurrence of UTEs that are not correlated to COVID-19 severity.

A review of ischemic stroke in COVID-19: currently known pathophysiological mechanisms

Coronavirus disease 2019 (COVID-19), the third type of coronavirus pneumonia after severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), is spreading widely worldwide now. This pneumonia causes not only respiratory symptoms but also multiple organ dysfunction, including thrombotic diseases such as ischemic stroke. The purpose of this review is to explore whether COVID-19 is a risk factor for ischemic stroke and its related pathophysiological mechanisms. Based on the high thrombosis rate and frequent strokes of COVID-19 patients, combined with related laboratory indicators and pathological results, the discussion is mainly from two aspects: nerve invasion and endothelial dysfunction. SARS-CoV-2 can directly invade the CNS through blood-borne and neuronal retrograde pathways, causing cerebrovascular diseases. In addition, the endothelial dysfunction in COVID-19 is almost certain. Cytokine storm causes thromboinflammation, and downregulation of ACE2 leads to RAS imbalance, which eventually lead to ischemic stroke.

SARS-CoV-2: Current trends in emerging variants, pathogenesis, immune responses, potential therapeutic, and vaccine development strategies

More than a year after the SARS-CoV-2 pandemic, the Coronavirus disease 19 (COVID-19) is still a major global challenge for scientists to understand the different dimensions of infection and find ways to prevent, treat, and develop a vaccine. On January 30, 2020, the world health organization (WHO) officially announced this new virus as an international health emergency. While many biological and mechanisms of pathogenicity of this virus are still unclear, it seems that cytokine storm resulting from an immune response against the virus is considered the main culprit of the severity of the disease. Despite many global efforts to control the SARS-CoV-2, several problems and challenges have been posed in controlling the COVID-19 infection. These problems include the various mutations, the emergence of variants with high transmissibility, the short period of immunity against the virus, the possibility of reinfection in people improved, lack of specific drugs, and problems in the development of highly sensitive and specific vaccines. In this review, we summarized the results of the current trend and the latest research studies on the characteristics of the structure and genome of the SARS-CoV- 2, new mutations and variants of SARS-CoV-2, pathogenicity, immune response, virus diagnostic tests, potential treatment, and vaccine candidate.

Coagulation abnormalities & thromboprophylaxis in COVID-19

The ongoing pandemic of novel coronavirus 2019 is rapidly evolving, and newer organ- and system-specific manifestations are being observed. Thrombotic complications and coagulopathy are frequent manifestations of the disease, especially in sick patients, which appear to be unique and distinct from sepsis-induced coagulopathy, disseminated intravascular coagulation and other viral infection-induced coagulation abnormalities. Elevated D-dimers and fibrinogen in the early stage of the disease with minimally deranged prothrombin time and platelet counts are prominent and distinguishing features. Venous and arterial thromboses, as opposed to bleeding events, are the major clinical correlates. There is much to be known about the pathogenesis of COVID-associated coagulopathy; however, the mechanisms overlap with thrombotic microangiopathy, haemophagocytic syndrome and antiphospholipid syndrome compounded by the diffuse endothelial damage. The recommendations regarding the treatment are still evolving, but antithrombotic therapy has a definite role in positive outcomes of sick patients.

Bioactive Molecules Derived from Snake Venoms with Therapeutic Potential for the Treatment of Thrombo-Cardiovascular Disorders Associated with COVID-19

As expected, several new variants of Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2) emerged and have been detected around the world throughout this Coronavirus Disease of 2019 (COVID-19) pandemic. Currently, there is no specific developed drug against COVID-19 and the challenge of developing effective antiviral strategies based on natural agents with different mechanisms of action becomes an urgent need and requires identification of genetic differences among variants. Such data is used to improve therapeutics to combat SARS-CoV-2 variants. Nature is known to offer many biotherapeutics from animal venoms, algae and plant that have been historically used in traditional medicine. Among these bioresources, snake venom displays many bioactivities of interest such as antiviral, antiplatelet, antithrombotic, anti-inflammatory, antimicrobial and antitumoral. COVID-19 is a viral respiratory sickness due to SARS-CoV-2 which induces thrombotic disorders due to cytokine storm, platelet hyperactivation and endothelial dysfunction. This review aims to: (1) present an overview on the infection, the developed thrombo-inflammatory responses and mechanisms of induced thrombosis of COVID-19 compared to other similar pathogenesis; (2) underline the role of natural compounds such as anticoagulant, antiplatelet and thrombolytic agents; (3) investigate the management of coagulopathy related to COVID-19 and provide insight on therapeutic such as venom compounds. We also summarize the updated advances on antiviral proteins and peptides derived from snake venoms that could weaken coagulopathy characterizing COVID-19.

Potential Physiological and Cellular Mechanisms of Exercise That Decrease the Risk of Severe Complications and Mortality Following SARS-CoV-2 Infection

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has unmasked mankind's vulnerability to biological threats. Although higher age is a major risk factor for disease severity in COVID-19, several predisposing risk factors for mortality are related to low cardiorespiratory and metabolic fitness, including obesity, cardiovascular disease, diabetes, and hypertension. Reaching physical activity (PA) guideline goals contribute to protect against numerous immune and inflammatory disorders, in addition to multi-morbidities and mortality. Elevated levels of cardiorespiratory fitness, being non-obese, and regular PA improves immunological function, mitigating sustained low-grade systemic inflammation and age-related deterioration of the immune system, or immunosenescence. Regular PA and being non-obese also improve the antibody response to vaccination. In this review, we highlight potential physiological, cellular, and molecular mechanisms that are affected by regular PA, increase the host antiviral defense, and may determine the course and outcome of COVID-19. Not only are the immune system and regular PA in relation to COVID-19 discussed, but also the cardiovascular, respiratory, renal, and hormonal systems, as well as skeletal muscle, epigenetics, and mitochondrial function.

Classical and Counter-Regulatory Renin-Angiotensin System: Potential Key Roles in COVID-19 Pathophysiology

In the current COVID-19 pandemic, severe acute respiratory syndrome coronavirus 2 uses angiotensin-converting enzyme-2 (ACE-2) receptors for cell entry, leading to ACE-2 dysfunction and downregulation, which disturb the balance between the classical and counter-regulatory renin-angiotensin system (RAS) in favor of the classical RAS. RAS dysregulation is one of the major characteristics of several cardiovascular diseases; thus, adjustment of this system is the main therapeutic target. RAS inhibitors-particularly angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor blockers (ARBs)-are commonly used for treatment of hypertension and cardiovascular disease. Patients with cardiovascular diseases are the group most commonly seen among those with COVID-19 comorbidity. At the beginning of this pandemic, a dilemma occurred regarding the use of ACEIs and ARBs, potentially aggravating cardiovascular and pulmonary dysfunction in COVID-19 patients. Urgent clinical trials from different countries and hospitals reported that there is no association between RAS inhibitor treatment and COVID-19 infection or comorbidity complication. Nevertheless, the disturbance of the RAS that is associated with COVID-19 infection and the potential treatment targeting this area have yet to be resolved. In this review, the link between the dysregulation of classical RAS and counter-regulatory RAS activities in COVID-19 patients with cardiovascular metabolic diseases is investigated. In addition, the latest findings based on ACEI and ARB administration and ACE-2 availability in relation to COVID-19, which may provide a better understanding of the RAS contribution to COVID-19 pathology, are discussed, as they are of the utmost importance amid the current pandemic.

SARS-CoV-2 Poorly Replicates in Cells of the Human Blood-Brain Barrier Without Associated Deleterious Effects

Various neurological symptoms have been associated to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection including headache, fever, anosmia, ageusia, but also, encephalitis, Guillain-Barre syndrome and ischemic stroke. Responsible for the current coronavirus disease (COVID-19) pandemic, SARS-CoV-2 may access and affect the central nervous system (CNS) by several pathways such as axonal retrograde transport or through interaction with the blood-brain barrier (BBB) or blood-cerebrospinal fluid (CSF) barrier. Here, we explored the molecular and cellular effects of direct SARS-CoV-2 infection of human BBB cells. We observed low replication of SARS-CoV-2 that was accompanied by very moderate inflammatory response. Using a human in vitro BBB model, we also described low replication levels without strong inflammatory response or modulation of endothelium integrity. Finally, using serum samples from COVID-19 patients, we highlighted strong concentrations of pro-inflammatory factors that did not perturb BBB integrity after short term exposure. Altogether, our results show that the main mechanism of brain access following SARS-CoV-2 infection does not seem to be directed by brain infection through endothelial cells.

ACE2 Down-Regulation May Act as a Transient Molecular Disease Causing RAAS Dysregulation and Tissue Damage in the Microcirculatory Environment Among COVID-19 Patients

Severe acute respiratory syndrome coronavirus 2, the etiologic agent of coronavirus disease 2019 (COVID-19) and the cause of the current pandemic, produces multiform manifestations throughout the body, causing indiscriminate damage to multiple organ systems, particularly the lungs, heart, brain, kidney, and vasculature. The aim of this review is to provide a new assessment of the data already available for COVID-19, exploring it as a transient molecular disease that causes negative regulation of angiotensin-converting enzyme 2, and consequently, deregulates the renin-angiotensin-aldosterone system, promoting important changes in the microcirculatory environment. Another goal of the article is to show how these microcirculatory changes may be responsible for the wide variety of injury mechanisms observed in different organs in this disease. The new concept of COVID-19 provides a unifying pathophysiological picture of this infection and offers fresh insights for a rational treatment strategy to combat this ongoing pandemic.

SARS-CoV-2 infection as a potential triggering factor for urticarial vasculitis during pregnancy: A case report

During the COVID-19 pandemic, physicians must maintain a high index of suspicion for COVID-19 in cases of urticarial vasculitis or other forms of urticaria. This is particularly important for acute presentations in otherwise asymptomatic individuals and pregnant women, where a prompt approach to the patient can prevent undesirable complications.

Acute Viral Illnesses and Ischemic Stroke: Pathophysiological Considerations in the Era of the COVID-19 Pandemic

The severe acute respiratory syndrome coronavirus 2 or coronavirus disease 2019 (COVID-19) pandemic has raised concerns about the correlation with this viral illness and increased risk of stroke. Although it is too early in the pandemic to know the strength of the association between COVID-19 and stroke, it is an opportune time to review the relationship between acute viral illnesses and stroke. Here, we summarize pathophysiological principles and available literature to guide understanding of how viruses may contribute to ischemic stroke. After a review of inflammatory mechanisms, we summarize relevant pathophysiological principles of vasculopathy, hypercoagulability, and hemodynamic instability. We will end by discussing mechanisms by which several well-known viruses may cause stroke in an effort to inform our understanding of the relationship between COVID-19 and stroke.

Thrombose und COVID-19

Die Prävalenz der venösen thromboembolischen (VTE) Ereignisse ist bei Coronavirus diesease 2019 (COVID-19) -Patienten hoch, insbesondere bei schwer Erkrankten. Patienten mit schwerer COVID-19 und VTE haben eine signifikant höhere Mortalität im Vergleich zu Patienten ohne VTE. Die Manifestation einer schweren Infektion mit Severe acute respiratory syndrome coronavirus-2 (SARS-CoV‑2) entspricht einem systemischen proinflammatorischen und prokoagulatorischen Phänotyp, der mit vaskulären Thrombosen nicht nur in den Venen, sondern auch in den Arterien, Kapillaren sowie mit einer Inflammation der Gefäße assoziiert ist. Ein erhöhter D‑Dimer-Spiegel kann als Indikator für VTE bei Patienten mit COVID-19 verwendet werden. Die meisten medizinischen Gesellschaften empfehlen eine VTE-Prophylaxe vorzugsweise mit niedermolekularen Heparinen (LMWH) bei allen stationären Patienten. Weitere Daten von randomisierten kontrollierten Studien (RCTs) über die optimale Antikoagulation und antithrombotische Therapie werden in der nahen Zukunft erwartet.

Hypercoagulopathy, acquired coagulation disorders and anticoagulation before, during and after extracorporeal membrane oxygenation in COVID-19: a case series

BACKGROUND

Thromboembolism and bleeding contribute to Coronavirus disease 2019 (COVID-19)'s morbidity and mortality and are also frequent complications of venovenous extracorporeal membrane oxygenation (vvECMO). As the interaction of the underlying pathologies caused by vvECMO in COVID-19 is barely understood, we designed this study to better differentiate coagulation disorders in COVID-19 patients before, during and after vvECMO-support.

METHODS

Observational case series, six consecutive patients with Coronavirus acute respiratory distress syndrome supported with vvECMO treated in the anaesthesiologic ICU in a third level University ECMO-centre. We measured routine coagulation parameters and assessed coagulation factors. We also conducted advanced von Willebrand factor (VWF) multimer analysis, platelet aggregometry and immunological screening.

RESULTS

We identified various phases of coagulation disorders: Initially, intensely activated coagulation with highly increased VWF and factor VIII activity in acute COVID-19, then severe acquired von Willebrand syndrome and platelet dysfunction during vvECMO leading to spontaneous bleeding and finally, hypercoagulopathy after vvECMO explantation. Five of six patients developed immunological abnormalities enhancing coagulation.

CONCLUSIONS

Coronavirus-induced coagulopathy and bleeding disorders during vvECMO cannot be discriminated via 'routine' coagulation tests. Precise and specific analyses followed by the appropriate treatment of coagulation disorders may help us develop tailored therapeutic concepts to better manage the phases described above.

Low ADAMTS13 Activity Correlates with Increased Mortality in COVID-19 Patients

The causes of coagulopathy associated with coronavirus disease 2019 (COVID-19) are poorly understood. We aimed to investigate the relationship between von Willebrand factor (VWF) biomarkers, intravascular hemolysis, coagulation, and organ damage in COVID-19 patients and study their association with disease severity and mortality. We conducted a retrospective study of 181 hospitalized COVID-19 patients randomly selected with balanced distribution of survivors and nonsurvivors. Patients who died had significantly lower ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity, significantly elevated lactate dehydrogenase levels, significantly increased shistocyte/RBC fragment counts, and significantly elevated VWF antigen and activity levels compared with patients discharged alive. These biomarkers correlate with markedly elevated D-dimers. Additionally, only 30% of patients who had an ADAMTS13 activity level of less than 43% on admission survived, yet 60% of patients survived who had an ADAMTS13 activity level of greater than 43% on admission. In conclusion, COVID-19 may present with low ADAMTS13 activity in a subset of hospitalized patients. Presence of schistocytes/RBC fragment and elevated D-dimer on admission may warrant a work-up for ADAMTS13 activity and VWF antigen and activity levels. These findings indicate the need for future investigation to study the relationship between endothelial and coagulation activation and the efficacy of treatments aimed at prevention and/or amelioration of microangiopathy in COVID-19.

Development of the Neuro-Immune-Vascular Plexus in the Ventricular Zone of the Prenatal Rat Neocortex

Microglial cells make extensive contacts with neural precursor cells (NPCs) and affiliate with vasculature in the developing cerebral cortex. But how vasculature contributes to cortical histogenesis is not yet fully understood. To better understand functional roles of developing vasculature in the embryonic rat cerebral cortex, we investigated the temporal and spatial relationships between vessels, microglia, and NPCs in the ventricular zone. Our results show that endothelial cells in developing cortical vessels extend numerous fine processes that directly contact mitotic NPCs and microglia; that these processes protrude from vessel walls and are distinct from tip cell processes; and that microglia, NPCs, and vessels are highly interconnected near the ventricle. These findings demonstrate the complex environment in which NPCs are embedded in cortical proliferative zones and suggest that developing vasculature represents a source of signaling with the potential to broadly influence cortical development. In summary, cortical histogenesis arises from the interplay among NPCs, microglia, and developing vasculature. Thus, factors that impinge on any single component have the potential to change the trajectory of cortical development and increase susceptibility for altered neurodevelopmental outcomes.

Anti-Infective, Anti-Inflammatory, and Immunomodulatory Properties of Breast Milk Factors for the Protection of Infants in the Pandemic From COVID-19

COVID-19 pandemic since the end of 2019 spreads worldwide, counting millions of victims. The viral invasion, systemic inflammation, and consequent organ failure are the gravest features of coronavirus disease 2019 (COVID-19), and they are associated with a high mortality rate. The aim of this study is to evaluate the role of breast milk in the COVID-19 pandemic, analyzing its antiviral, anti-inflammatory, and immunoregulatory effects due to its bioactive components, so numerous and important for the protection of infants. The study tried to demonstrate that all the components of human milk are capable of performing functions on all the pathogenic events recognized and described in COVID-19 disease. Those human milk factors are well-tolerated and practically free of side effects, so breast milk should become a research topic to discover therapies even in this epidemic. In the first part, the mechanisms of protection and defense of the breast milk elements will be delineated; in the second section, it will describe the human milk effects in viral infections and it will be hypothesized how the known mechanisms could act in COVID infection.

Acute Limb Ischemia in Critically ill COVID-19 Patients: a Case Series and Literature Review

Background: The vascular burden increased by COVID-19 infection and including acute limb ischemia (ALI) quickly emerged as a major medical challenge with devastating consequences such as limb loss, multiorgan dysfunction and death. We report a case series of COVID-19 infection associated with ALI to raise awareness and knowledge towards this life-threatening association. Methods: COVIDS-19 patients with acute limb ischemia (ALI) managed in a Moroccan 14 beds COVID-19 ICU between March 2020 and January 2021, were reviewed. Data collected included demographics, clinical presentation, treatments and outcomes. Results: Over the 10-month period, our ICU cared for 407 hospitalized patients with confirmed COVID-19. A total of 6 COVID-19 patients with ALI were identified. The mean age was 61 years (52 - 70) and 5 were men. The most common preexisting condition was diabetes (50%). The mean CRP level was 219 mg/L. Five patients had thrombus in multiple locations. No concomitant deep vein thrombosis was identified. Four patients presented with signs of acute No arterial ischemia with or without respiratory symptoms and were subsequently diagnosed with COVID-19. The remaining two patients developed ischemia during hospitalization. Mean SOFA score was 5 (2 -9). Respiratory support, corticosteroids and heparin therapies were used in all patients. Intubation and vasopressors were required in four patients. Revascularization was performed in five patients and reintervention was necessary in three cases. Four patients died in the ICU while two were successfully discharged. Conclusion: ALI in COVID-19 patients is a challenging life-threatening vascular emergency that requires appropriate multidisciplinary management (intensivists, anesthesiologists, vascular surgeons and interventionists, radiologists, haematologists…) and further studies focused on anticoagulation. Keywords: Acute Limb ischemia, Coagulopathy, COVID-19, SARS-CoV-2, Thrombosis

Role of the SphK-S1P-S1PRs pathway in invasion of the nervous system by SARS-CoV-2 infection

Global spread of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is still ongoing. Before an effective vaccine is available, the development of potential treatments for resultant coronavirus disease 2019 (COVID‐19) is crucial. One of the disease hallmarks is hyper‐inflammatory responses, which usually leads to a severe lung disease. Patients with COVID‐19 also frequently suffer from neurological symptoms such as acute diffuse encephalomyelitis, brain injury and psychiatric complications. The metabolic pathway of sphingosine‐1‐phosphate (S1P) is a dynamic regulator of various cell types and disease processes, including the nervous system. It has been demonstrated that S1P and its metabolic enzymes, regulating neuroinflammation and neurogenesis, exhibit important functions during viral infection. S1P receptor 1 (S1PR1) analogues including AAL‐R and RP‐002 inhibit pathophysiological responses at the early stage of H1N1 virus infection and then play a protective role. Fingolimod (FTY720) is an S1P receptor modulator and is being tested for treating COVID‐19. Our review provides an overview of SARS‐CoV‐2 infection and critical role of the SphK‐S1P‐SIPR pathway in invasion of SARS‐CoV‐2 infection, particularly in the central nervous system (CNS). This may help design therapeutic strategies based on the S1P‐mediated signal transduction, and the adjuvant therapeutic effects of S1P analogues to limit or prevent the interaction between the host and SARS‐CoV‐2, block the spread of the SARS‐CoV‐2, and consequently treat related complications in the CNS.

Long-Lasting Cognitive Abnormalities after COVID-19

Considering the mechanisms capable of causing brain alterations in COVID-19, we aimed to study the occurrence of cognitive abnormalities in the months following hospital discharge. We recruited 38 (aged 22-74 years; 27 males) patients hospitalized for complications of SARS-CoV-2 infection in nonintensive COVID units. Participants underwent neuropsychological testing about 5 months after hospital discharge. Of all patients, 42.1% had processing speed deficits, while 26.3% showed delayed verbal recall deficits. Twenty-one percent presented with deficits in both processing speed and verbal memory. Bivariate analysis revealed a positive correlation between the lowest arterial oxygen partial pressure (PaO2) to fractional inspired oxygen (FiO2) (P/F) ratio during hospitalization and verbal memory consolidation performance (SRT-LTS score, r = 0.404, p = 0.027), as well as a positive correlation between SpO2 levels upon hospital arrival and delayed verbal recall performance (SRT-D score, rs = 0.373, p = 0.042). Acute respiratory distress syndrome (ARDS) during hospitalization was associated with worse verbal memory performance (ARDS vs. no ARDS: SRT-LTS mean score = 30.63 ± 13.33 vs. 44.50 ± 13.16, p = 0.007; SRT-D mean score = 5.95 ± 2.56 vs. 8.10 ± 2.62, p = 0.029). Cognitive abnormalities can frequently be found in COVID-19 patients 5 months after hospital discharge. Increased fatigability, deficits of concentration and memory, and overall decreased cognitive speed months after hospital discharge can interfere with work and daily activities.

Thymoquinone: A Tie-Breaker in SARS-CoV2-Infected Cancer Patients?

Since the beginning of the SARS-CoV-2(severe acute respiratory syndrome-coronavirus-2) pandemic, arace to develop a vaccine has been initiated, considering the massive and rather significant economic and healthcare hits that this virus has caused. The pathophysiology occurring following COVID-19(coronavirus disease-2019) infection has givenhints regarding the supportive and symptomatic treatments to establish for patients, as no specific anti-SARS-CoV-2 is available yet. Patient symptoms vary greatly and range from mild symptoms to severe fatal complications. Supportive treatments include antipyretics, antiviral therapies, different combinations of broad-spectrum antibiotics, hydroxychloroquine and plasma transfusion. Unfortunately, cancer patients are at higher risk of viral infection and more likely to develop serious complications due to their immunocompromised state, the fact that they are already administering multiple medications, as well as combined comorbidity compared to the general population. It may seem impossible to find a drug that possesses both potent antiviral and anticancer effects specifically against COVID-19 infection and its complications and the existing malignancy, respectively. Thymoquinone (TQ) is the most pharmacologically active ingredient in Nigella sativa seeds (black seeds); it is reported to have anticancer, anti-inflammatory and antioxidant effects in various settings. In this review, we will discuss the multiple effects of TQ specifically against COVID-19, its beneficial effects against COVID-19 pathophysiology and multiple-organ complications, its use as an adjuvant for supportive COVID-19 therapy and cancer therapy, and finally, its anticancer effects.

Case Report: Multiple Strokes and Digital Ischemia in a Young COVID-19 Patient

COVID-19 is an infectious disease caused by SARS-CoV-2. This enveloped RNA coronavirus primarily has tropism for the respiratory tract. However, it has also been shown to have various extrapulmonary manifestations such as pulmonary embolism, ischemic strokes, deep venous thrombosis, or arterial thrombosis. We present a case of a 34-year-old woman who had severe COVID-19 infection with no respiratory symptoms and developed strokes in multiple vascular territories and digital ischemia due to thrombosis formation in the brachial circulation of her arm despite receiving therapeutic anticoagulation.

Neurological issues in children with COVID-19

Coronavirus disease 2019 (COVID-19) usually leads to a mild infectious disease course in children, but serious complications may occur in conjunction with both acute infection and associated phenomena such as the multisystem inflammatory syndrome in children (MIS-C). Neurological symptoms, which have been predominantly reported in adults, range from mild headache to seizure, peripheral neuropathy, stroke, demyelinating disorders, and encephalopathy. Similar to respiratory and cardiac manifestations of COVID-19, neurological complications present differently based on age and underlying comorbidities. This review provides a concise overview of the neurological conditions seen in the context of COVID-19, as well as potential mechanisms and long-term implications of COVID-19 in the pediatric population from literature reviews and primary data collected at NewYork-Presbyterian Morgan Stanley Children's Hospital.

Angiotensin-converting enzyme 2 and COVID-19 in cardiorenal diseases

The rapid spread of the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has brought into focus the key role of angiotensin-converting enzyme 2 (ACE2), which serves as a cell surface receptor required for the virus to enter cells. SARS-CoV-2 can decrease cell surface ACE2 directly by internalization of ACE2 bound to the virus and indirectly by increased ADAM17 (a disintegrin and metalloproteinase 17)-mediated shedding of ACE2. ACE2 is widely expressed in the heart, lungs, vasculature, kidney and the gastrointestinal (GI) tract, where it counteracts the deleterious effects of angiotensin II (AngII) by catalyzing the conversion of AngII into the vasodilator peptide angiotensin-(1-7) (Ang-(1-7)). The down-regulation of ACE2 by SARS-CoV-2 can be detrimental to the cardiovascular system and kidneys. Further, decreased ACE2 can cause gut dysbiosis, inflammation and potentially worsen the systemic inflammatory response and coagulopathy associated with SARS-CoV-2. This review aims to elucidate the crucial role of ACE2 both as a regulator of the renin-angiotensin system and a receptor for SARS-CoV-2 as well as the implications for Coronavirus disease 19 and its associated cardiovascular and renal complications.

ACE2: the molecular doorway to SARS-CoV-2

The angiotensin-converting enzyme 2 (ACE2) is the host functional receptor for the new virus SARS-CoV-2 causing Coronavirus Disease 2019. ACE2 is expressed in 72 different cell types. Some factors that can affect the expression of the ACE2 are: sex, environment, comorbidities, medications (e.g. anti-hypertensives) and its interaction with other genes of the renin-angiotensin system and other pathways. Different factors can affect the risk of infection of SARS-CoV-2 and determine the severity of the symptoms. The ACE2 enzyme is a negative regulator of RAS expressed in various organ systems. It is with immunity, inflammation, increased coagulopathy, and cardiovascular disease. In this review, we describe the genetic and molecular functions of the ACE2 receptor and its relation with the physiological and pathological conditions to better understand how this receptor is involved in the pathogenesis of COVID-19. In addition, it reviews the different comorbidities that interact with SARS-CoV-2 in which also ACE2 plays an important role. It also describes the different factors that interact with the virus that have an influence in the expression and functional activities of the receptor. The goal is to provide the reader with an understanding of the complexity and importance of this receptor.

Extracellular RNA as a Versatile DAMP and Alarm Signal That Influences Leukocyte Recruitment in Inflammation and Infection

Upon vascular injury, tissue damage, ischemia, or microbial infection, intracellular material such as nucleic acids and histones is liberated and comes into contact with the vessel wall and circulating blood cells. Such "Danger-associated molecular patterns" (DAMPs) may thus have an enduring influence on the inflammatory defense process that involves leukocyte recruitment and wound healing reactions. While different species of extracellular RNA (exRNA), including microRNAs and long non-coding RNAs, have been implicated to influence inflammatory processes at different levels, recent in vitro and in vivo work has demonstrated a major impact of ribosomal exRNA as a prominent DAMP on various steps of leukocyte recruitment within the innate immune response. This includes the induction of vascular hyper-permeability and vasogenic edema by exRNA via the activation of the "vascular endothelial growth factor" (VEGF) receptor-2 system, as well as the recruitment of leukocytes to the inflamed endothelium, the M1-type polarization of inflammatory macrophages, or the role of exRNA as a pro-thrombotic cofactor to promote thrombosis. Beyond sterile inflammation, exRNA also augments the docking of bacteria to host cells and the subsequent microbial invasion. Moreover, upon vessel occlusion and ischemia, the shear stress-induced release of exRNA initiates arteriogenesis (i.e., formation of natural vessel bypasses) in a multistep process that resembles leukocyte recruitment. Although exRNA can be counteracted for by natural circulating RNase1, under the conditions mentioned, only the administration of exogenous, thermostable, non-toxic RNase1 provides an effective and safe therapeutic regimen for treating the damaging activities of exRNA. It remains to be investigated whether exRNA may also influence viral infections (including COVID-19), e.g., by supporting the interaction of host cells with viral particles and their subsequent invasion. In fact, as a consequence of the viral infection cycle, massive amounts of exRNA are liberated, which can provoke further tissue damage and enhance virus dissemination. Whether the application of RNase1 in this scenario may help to limit the extent of viral infections like COVID-19 and impact on leukocyte recruitment and emigration steps in immune defense in order to limit the extent of associated cardiovascular diseases remains to be studied.

The Contribution of Endothelial Dysfunction in Systemic Injury Subsequent to SARS-Cov-2 Infection

SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) infection is associated, alongside with lung infection and respiratory disease, to cardiovascular dysfunction that occurs at any stage of the disease. This includes ischemic heart disease, arrhythmias, and cardiomyopathies. The common pathophysiological link between SARS-CoV-2 infection and the cardiovascular events is represented by coagulation abnormalities and disruption of factors released by endothelial cells, which contribute in maintaining the blood vessels into an anti-thrombotic state. Thus, early alteration of the functionality of endothelial cells, which may be found soon after SARS-CoV-2 infection, seems to represent the major target of a SARS CoV-2 disease state and accounts for the systemic vascular dysfunction that leads to a detrimental effect in terms of hospitalization and death accompanying the disease. In particular, the molecular interaction of SARS-CoV-2 with the ACE2 receptor located in the endothelial cell surface, either at the pulmonary and systemic level, leads to early impairment of endothelial function, which, in turn, is followed by vascular inflammation and thrombosis of peripheral blood vessels. This highlights systemic hypoxia and further aggravates the vicious circle that compromises the development of the disease, leading to irreversible tissue damage and death of people with SARS CoV-2 infection. The review aims to assess some recent advances to define the crucial role of endothelial dysfunction in the pathogenesis of vascular complications accompanying SARS-CoV-2 infection. In particular, the molecular mechanisms associated with the interaction of SARS CoV-2 with the ACE2 receptor located on the endothelial cells are highlighted to support its role in compromising endothelial cell functionality. Finally, the consequences of endothelial dysfunction in enhancing pro-inflammatory and pro-thrombotic effects of SARS-CoV-2 infection are assessed in order to identify early therapeutic interventions able to reduce the impact of the disease in high-risk patients.

Pharmacological and cardiovascular perspectives on the treatment of COVID-19 with chloroquine derivatives

The novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) and an ongoing severe pandemic. Curative drugs specific for COVID-19 are currently lacking. Chloroquine phosphate and its derivative hydroxychloroquine, which have been used in the treatment and prevention of malaria and autoimmune diseases for decades, were found to inhibit SARS-CoV-2 infection with high potency in vitro and have shown clinical and virologic benefits in COVID-19 patients. Therefore, chloroquine phosphate was first used in the treatment of COVID-19 in China. Later, under a limited emergency-use authorization from the FDA, hydroxychloroquine in combination with azithromycin was used to treat COVID-19 patients in the USA, although the mechanisms of the anti-COVID-19 effects remain unclear. Preliminary outcomes from clinical trials in several countries have generated controversial results. The desperation to control the pandemic overrode the concerns regarding the serious adverse effects of chloroquine derivatives and combination drugs, including lethal arrhythmias and cardiomyopathy. The risks of these treatments have become more complex as a result of findings that COVID-19 is actually a multisystem disease. While respiratory symptoms are the major clinical manifestations, cardiovascular abnormalities, including arrhythmias, myocarditis, heart failure, and ischemic stroke, have been reported in a significant number of COVID-19 patients. Patients with preexisting cardiovascular conditions (hypertension, arrhythmias, etc.) are at increased risk of severe COVID-19 and death. From pharmacological and cardiovascular perspectives, therefore, the treatment of COVID-19 with chloroquine and its derivatives should be systematically evaluated, and patients should be routinely monitored for cardiovascular conditions to prevent lethal adverse events.