Harnessing nitric oxide for preventing, limiting and treating the severe pulmonary consequences of COVID-19

Prognostic significance of hypertension history and blood pressure on admission in Japanese patients with coronavirus disease 2019: integrative analysis from the Japan COVID-19 Task Force

The effect of preexisting hypertension on coronavirus disease 2019 (COVID-19) prognosis remains controversial. Additionally, no studies have compared the association between blood pressure (BP) indices on admission and COVID-19 outcomes using preexisting hypertension status. Therefore, this study aimed to investigate the association between preexisting hypertension and COVID-19 outcomes in Japanese patients with COVID-19 and assess the impact of BP indices on admission on clinical outcomes in patients with and without preexisting hypertension. Preexisting hypertension presence was confirmed based on the patient's clinical history. Critical outcomes were defined as high-flow oxygen use, non-invasive and invasive positive-pressure ventilation, extracorporeal membrane oxygenation, or death during hospitalization. Preexisting hypertension was observed in 64.6% of the patients. Multivariable logistic regression analysis of severe COVID-19 risk factors indicated that preexisting hypertension was independently associated with critical outcomes [adjusted odds ratio (OR): 1.35; 95% confidence interval (CI): 1.05-1.73]. Low or high BP and high pulse pressure on admission were associated with critical outcomes in patients without preexisting hypertension [OR for systolic BP < 100 mmHg: 2.13, 95% CI: 1.21-3.75; OR for high BP stage 2 (160-179 systolic and/or 100-109 mmHg diastolic BP): 2.13, 95% CI: 1.27-3.58; OR for pulse pressure ≥60 mmHg: 1.68, 95% CI: 1.14-2.48]. Preexisting hypertension is a risk factor for critical outcomes in Japanese patients with COVID-19. BP indices are useful biomarkers for predicting COVID-19 outcomes, particularly in patients without preexisting hypertension. Thus, hypertension history, systolic BP, and pulse pressure should be assessed to predict severe COVID-19 outcomes.

IFN-γ-mediated control of SARS-CoV-2 infection through nitric oxide

Introduction

The COVID-19 pandemic has highlighted the need to identify mechanisms of antiviral host defense against SARS-CoV-2. One such mediator is interferon-g (IFN-γ), which, when administered to infected patients, is reported to result in viral clearance and resolution of pulmonary symptoms. IFN-γ treatment of a human lung epithelial cell line triggered an antiviral activity against SARS-CoV-2, yet the mechanism for this antiviral response was not identified.

Methods

Given that IFN-γ has been shown to trigger antiviral activity via the generation of nitric oxide (NO), we investigated whether IFN-γ induction of antiviral activity against SARS-CoV-2 infection is dependent upon the generation of NO in human pulmonary epithelial cells. We treated the simian epithelial cell line Vero E6 and human pulmonary epithelial cell lines, including A549-ACE2, and Calu-3, with IFN-γ and observed the resulting induction of NO and its effects on SARS-CoV-2 replication. Pharmacological inhibition of inducible nitric oxide synthase (iNOS) was employed to assess the dependency on NO production. Additionally, the study examined the effect of interleukin-1b (IL-1β) on the IFN-g-induced NO production and its antiviral efficacy.

Results

Treatment of Vero E6 cells with IFN-γ resulted in a dose-responsive induction of NO and an inhibitory effect on SARS-CoV-2 replication. This antiviral activity was blocked by pharmacologic inhibition of iNOS. IFN-γ also triggered a NO-mediated antiviral activity in SARS-CoV-2 infected human lung epithelial cell lines A549-ACE2 and Calu-3. IL-1β enhanced IFN-γ induction of NO, but it had little effect on antiviral activity.

Discussion

Given that IFN-g has been shown to be produced by CD8+ T cells in the early response to SARS-CoV-2, our findings in human lung epithelial cell lines, of an IFN-γ-triggered, NO-dependent, links the adaptive immune response to an innate antiviral pathway in host defense against SARS-CoV-2. These results underscore the importance of IFN-γ and NO in the antiviral response and provide insights into potential therapeutic strategies for COVID-19.

Inhaled nitric oxide: can it serve as a savior for COVID-19 and related respiratory and cardiovascular diseases?

Nitric oxide (NO), as an important gaseous medium, plays a pivotal role in the human body, such as maintaining vascular homeostasis, regulating immune-inflammatory responses, inhibiting platelet aggregation, and inhibiting leukocyte adhesion. In recent years, the rapid prevalence of coronavirus disease 2019 (COVID-19) has greatly affected the daily lives and physical and mental health of people all over the world, and the therapeutic efficacy and resuscitation strategies for critically ill patients need to be further improved and perfected. Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator, and some studies have demonstrated its potential therapeutic use for COVID-19, severe respiratory distress syndrome, pulmonary infections, and pulmonary hypertension. In this article, we describe the biochemistry and basic characteristics of NO and discuss whether iNO can act as a "savior" for COVID-19 and related respiratory and cardiovascular disorders to exert a potent clinical protective effect.

Gasotransmitters in non-alcoholic fatty liver disease: just the tip of the iceberg

Non-alcoholic fatty liver disease (NAFLD) is a clinicopathological syndrome characterized by fatty lesions and fat accumulation in hepatic parenchymal cells, which is in the absence of excessive alcohol consumption or definite liver damage factors. The exact pathogenesis of NAFLD is not fully understood, but it is now recognized that oxidative stress, insulin resistance, and inflammation are essential mechanisms involved in the development and treatment of NAFLD. NAFLD therapy aims to stop, delay or reverse disease progressions, as well as improve the quality of life and clinical outcomes of patients with NAFLD. Gasotransmitters are produced by enzymatic reactions, regulated through metabolic pathways in vivo, which can freely penetrate cell membranes with specific physiological functions and targets. Three gasotransmitters, nitric oxide, carbon monoxide, and hydrogen sulfide have been discovered. Gasotransmitters exhibit the effects of anti-inflammatory, anti-oxidant, vasodilatory, and cardioprotective agents. Gasotransmitters and their donors can be used as new gas-derived drugs and provide new approaches to the clinical treatment of NAFLD. Gasotransmitters can modulate inflammation, oxidative stress, and numerous signaling pathways to protect against NAFLD. In this paper, we mainly review the status of gasotransmitters research on NAFLD. It provides clinical applications for the future use of exogenous and endogenous gasotransmitters for the treatment of NAFLD.

An update on vaccine status and the role of nanomedicine against SARS-CoV-2: A narrative review

Background and Aims

Coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 novel coronavirus, is a highly communicable disease that gave rise to the ongoing pandemic. Despite prompt action across many laboratories in many countries, effective management of this disease is still out of reach. The focus of this review is to describe various vaccination approaches and nanomedicine-based delivery systems against COVID-19.

Methods

The articles included in this study were searched and added from different electronic databases, including PubMed, Scopus, Cochrane, Embase, and preprint databases.

Results

Mass immunization with vaccines is currently at the forefront of COVID-19 infection control. Such vaccines are live attenuated vaccines, inactivated vaccines, nucleic acid-based vaccines, protein subunit vaccines, viral-vector vaccines, and virus-like particle platforms. However, many promising avenues are currently being explored in laboratory and clinical settings, including treatment options, prevention, diagnosis, and management of the disease. Soft nanoparticles like lipid nanoparticles (solid lipid nanoparticles (SLNPs), liposomes, nanostructured lipid carriers, nanoemulsions, and protein nanoparticles play an essential role in nanomedicine. Because of their unique and excellent properties, nanomedicines have potential applications in treating COVID-19 disease.

Conclusions

This review work provides an overview of the therapeutic aspects of COVID-19, including vaccination and the role of nanomedicines in the diagnosis, treatment, and prevention of COVID-19.

The role of asymmetric dimethylarginine (ADMA) in COVID-19: association with respiratory failure and predictive role for outcome

We aimed to assess the potential role of Asymmetric dimethylarginine (ADMA) in conditioning respiratory function and pulmonary vasoregulation during Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) infection. Within 72 h from admission, samples from 90 COVID-19 patients were assessed for ADMA, SDMA, L-arginine concentrations. In addition to classical statistics, patients were also clustered by a machine learning approach according to similar features. Multivariable analysis showed that C-reactive protein (OR 1.012), serum ADMA (OR 4.652), white blood cells (OR = 1.118) and SOFA (OR = 1.495) were significantly associated with negative outcomes. Machine learning-based clustering showed three distinct clusters: (1) patients with low severity not requiring invasive mechanical ventilation (IMV), (2) patients with moderate severity and respiratory failure whilst not requiring IMV, and (3) patients with highest severity requiring IMV. Serum ADMA concentration was significantly associated with disease severity and need for IMV although less pulmonary vasodilation was observed by CT scan. High serum levels of ADMA are indicative of high disease severity and requirement of mechanical ventilation. Serum ADMA at the time of hospital admission may therefore help to identify COVID-19 patients at high risk of deterioration and negative outcome.

Comparison of Vitamin D and Resveratrol Performances in COVID-19

Over the last few years, we have experienced the infection generated by severe respiratory syndrome coronavirus 2 (SARS-CoV-2) often resulting in an exaggerated immune reaction and systemic inflammation. The preferred treatments against SARS-CoV-2 were those that mitigated immunological/inflammatory dysfunction. A variety of observational epidemiological studies have reported that vitamin D deficiency is often a crucial factor in many inflammatory diseases and autoimmune diseases, as well as the susceptibility to contract infectious diseases, including acute respiratory infections. Similarly, resveratrol regulates immunity, modifying the gene expression and the release of proinflammatory cytokines in the immune cells. Therefore, it plays an immunomodulatory role that can be beneficial in the prevention and development of non-communicable diseases associated with inflammation. Since both vitamin D and resveratrol also act as immunomodulators in inflammatory pathologies, many studies have paid particular attention to an integrated treatment of either vitamin D or resveratrol in the immune reaction against SARS-CoV-2 infections. This article offers a critical evaluation of published clinical trials that have examined the use of vitamin D or resveratrol as adjuncts in COVID-19 management. Furthermore, we aimed to compare the anti-inflammatory and antioxidant properties linked to the modulation of the immune system, along with antiviral properties of both vitamin D and resveratrol.

Advanced Nitric Oxide Generating Nanomedicine for Therapeutic Applications

Nitric oxide (NO), a gaseous transmitter extensively present in the human body, regulates vascular relaxation, immune response, inflammation, neurotransmission, and other crucial functions. Nitrite donors have been used clinically to treat angina, heart failure, pulmonary hypertension, and erectile dysfunction. Based on NO's vast biological functions, it further can treat tumors, bacteria/biofilms and other infections, wound healing, eye diseases, and osteoporosis. However, delivering NO is challenging due to uncontrolled blood circulation release and a half-life of under five seconds. With advanced biotechnology and the development of nanomedicine, NO donors packaged with multifunctional nanocarriers by physically embedding or chemically conjugating have been reported to show improved therapeutic efficacy and reduced side effects. Herein, we review and discuss recent applications of NO nanomedicines, their therapeutic mechanisms, and the challenges of NO nanomedicines for future scientific studies and clinical applications. As NO enables the inhibition of the replication of DNA and RNA in infectious microbes, including COVID-19 coronaviruses and malaria parasites, we highlight the potential of NO nanomedicines for antipandemic efforts. This review aims to provide deep insights and practical hints into design strategies and applications of NO nanomedicines.

Hydroxytyrosol and Arginine as Antioxidant, Anti-Inflammatory and Immunostimulant Dietary Supplements for COVID-19 and Long COVID

Phytochemicals from plant extracts are becoming increasingly popular in the world of food science and technology because they have positive effects on human health. In particular, several bioactive foods and dietary supplements are being investigated as potential treatments for chronic COVID. Hydroxytyrosol (HXT) is a natural antioxidant, found in olive oil, with antioxidant anti-inflammatory properties that has been consumed by humans for centuries without reported adverse effects. Its use was approved by the European Food Safety Authority as a protective agent for the cardiovascular system. Similarly, arginine is a natural amino acid with anti-inflammatory properties that can modulate the activity of immune cells, reducing the production of pro-inflammatory cytokines such as IL-6 and TNF-α. The properties of both substances may be particularly beneficial in the context of COVID-19 and long COVID, which are characterised by inflammation and oxidative stress. While l-arginine promotes the formation of ^•NO, HXT prevents oxidative stress and inflammation in infected cells. This combination could prevent the formation of harmful peroxynitrite, a potent pro-inflammatory substance implicated in pneumonia and COVID-19-associated organ dysfunction, as well as reduce inflammation, improve immune function, protect against free radical damage and prevent blood vessel injury. Further research is needed to fully understand the potential benefits of HXT and arginine in the context of COVID-19.

Canine Coronavirus Infection Modulates the Biogenesis and Composition of Cell-Derived Extracellular Vesicles

Coronavirus (CoV) has persistently become a global health concern causing various diseases in a wide variety of hosts, including humans, birds, and companion animals. However, the virus-mediated responses in animal hosts have not been studied extensively due to pathogenesis complexity and disease developments. Extracellular vesicles (EVs) are widely explored in viral infections for their intercellular communication, nanocarrier, and immunomodulatory properties. We proposed that coronavirus hijacks the host exosomal pathway and modulates the EV biogenesis, composition, and protein trafficking in the host. In the present study, Crandell-Rees feline kidney (CRFK) cells were infected with canine coronavirus (CCoV) in an exosome-free medium at the multiplicity of infection (MOI) of 400 infectious units (IFU) at various time points. The cell viability was significantly decreased over time, as determined by the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Post-infection EVs were isolated, and transmission electron microscopy (TEM) showed the presence of small EVs (sEVs) after infection. NanoSight particle tracking analysis (NTA) revealed that EV sizes averaged between 100 and 200 nm at both incubation times; however, the mean size of infection-derived EVs was significantly decreased at 48 h when compared to uninfected control EVs. Quantitative analysis of protein levels performed by dot blot scanning showed that the expression levels of ACE-2, annexin-V, flotillin-1, TLR-7, LAMP, TNF-α, caspase-1, caspase-8, and others were altered in EVs after infection. Our findings suggested that coronavirus infection impacts cell viability, modulates EV biogenesis, and alters cargo composition and protein trafficking in the host, which could impact viral progression and disease development. Future experiments with different animal CoVs will provide a detailed understanding of host EV biology in infection pathogenesis and progression. Hence, EVs could offer a diagnostic and therapeutic tool to study virus-mediated host responses that could be extended to study the interspecies jump of animal CoVs to cause infection in humans.

Potential for Early Noninvasive COVID-19 Detection Using Electronic-Nose Technologies and Disease-Specific VOC Metabolic Biomarkers

The established efficacy of electronic volatile organic compound (VOC) detection technologies as diagnostic tools for noninvasive early detection of COVID-19 and related coronaviruses has been demonstrated from multiple studies using a variety of experimental and commercial electronic devices capable of detecting precise mixtures of VOC emissions in human breath. The activities of numerous global research teams, developing novel electronic-nose (e-nose) devices and diagnostic methods, have generated empirical laboratory and clinical trial test results based on the detection of different types of host VOC-biomarker metabolites from specific chemical classes. COVID-19-specific volatile biomarkers are derived from disease-induced changes in host metabolic pathways by SARS-CoV-2 viral pathogenesis. The unique mechanisms proposed from recent researchers to explain how COVID-19 causes damage to multiple organ systems throughout the body are associated with unique symptom combinations, cytokine storms and physiological cascades that disrupt normal biochemical processes through gene dysregulation to generate disease-specific VOC metabolites targeted for e-nose detection. This paper reviewed recent methods and applications of e-nose and related VOC-detection devices for early, noninvasive diagnosis of SARS-CoV-2 infections. In addition, metabolomic (quantitative) COVID-19 disease-specific chemical biomarkers, consisting of host-derived VOCs identified from exhaled breath of patients, were summarized as possible sources of volatile metabolic biomarkers useful for confirming and supporting e-nose diagnoses.

Targeted protein S-nitrosylation of ACE2 inhibits SARS-CoV-2 infection

Prevention of infection and propagation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a high priority in the Coronavirus Disease 2019 (COVID-19) pandemic. Here we describe S-nitrosylation of multiple proteins involved in SARS-CoV-2 infection, including angiotensin-converting enzyme 2 (ACE2), the receptor for viral entry. This reaction prevents binding of ACE2 to the SARS-CoV-2 spike protein, thereby inhibiting viral entry, infectivity and cytotoxicity. Aminoadamantane compounds also inhibit coronavirus ion channels formed by envelope (E) protein. Accordingly, we developed dual-mechanism aminoadamantane nitrate compounds that inhibit viral entry and, thus, the spread of infection by S-nitrosylating ACE2 via targeted delivery of the drug after E protein channel blockade. These non-toxic compounds are active in vitro and in vivo in the Syrian hamster COVID-19 model and, thus, provide a novel avenue to pursue therapy.

The role of arginine and endothelial nitric oxide synthase in the pathogenesis of Covid-19 complicated by metabolic syndrome

This literature review presents the role of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO), as well as arginine, the enzyme substrate, in the disease of metabolic syndrome and COVID-19 (SARS-CoV-2 virus). Metabolic syndrome is a combination of obesity, insulin resistance, hyperglycemia, dyslipidemia and hypertension. It has been shown that in elderly people, patients with obesity, metabolic syndrome, type 2 diabetes mellitus (DM2), and patients with COVID-19, endothelial dysfunction (ED) and vascular endothelial activation are detected. ED is the main cause of a number of pathological conditions during the development of COVID-19 and earlier in patients with metabolic syndrome, while a sharp drop in the level of nitric oxide (NO) is detected due to a decrease in the expression and activity of eNO synthase and enzyme depletion, which leads to a violation of the integrity of bloodvessels, that is, to vasoconstrictive, inflammatory and thrombotic conditions, followed by ischemia of organs and edema of tissues. It should be noted that metabolic syndrome, DM2, hypertension and obesity, in particular, are age-related diseases, and it is known that blood glucose levels increase with age, which reduces the bioavailability of NO in endothelial cells. Defects in the metabolism of NO cause dysfunction in the pulmonary blood vessels, the level of NO decreases, which leads to impaired lung function and coagulopathy. The review presents possible mechanisms of these disorders associated with ED, the release of eNO synthase, changes in phosphorylation and regulation of enzyme activity, as well as insulin resistance. A modern view of the role of the polymorphism of the eNO synthase gene in the development of these pathologies is presented. To increase the level of endothelial NO, drugs are offered that regulate the bioavailability of NO. These include arginine, agonist NO – minoxidil, steroid hormones, statins, metformin. However, further research and clinical trials are needed to develop treatment strategies that increase NO levels in the endothelium.

The Renin-Angiotensin-Aldosterone System, Nitric Oxide, and Hydrogen Sulfide at the Crossroads of Hypertension and COVID-19: Racial Disparities and Outcomes

Coronavirus disease 2019 is caused by SARS-CoV-2 and is more severe in the elderly, racial minorities, and those with comorbidities such as hypertension and diabetes. These pathologies are often controlled with medications involving the renin-angiotensin-aldosterone system (RAAS). RAAS is an endocrine system involved in maintaining blood pressure and blood volume through components of the system. SARS-CoV-2 enters the cells through ACE2, a membrane-bound protein related to RAAS. Therefore, the use of RAAS inhibitors could worsen the severity of COVID-19's symptoms, especially amongst those with pre-existing comorbidities. Although a vaccine is currently available to prevent and reduce the symptom severity of COVID-19, other options, such as nitric oxide and hydrogen sulfide, may also have utility to prevent and treat this virus.

Endothelial Dysfunction in COVID-19: Potential Mechanisms and Possible Therapeutic Options

SARS-CoV-2, a novel coronavirus found in Wuhan (China) at the end of 2019, is the etiological agent of the current pandemic that is a heterogeneous disease, named coronavirus disease 2019 (COVID-19). SARS-CoV-2 affects primarily the lungs, but it can induce multi-organ involvement such as acute myocardial injury, myocarditis, thromboembolic eventsandrenal failure. Hypertension, chronic kidney disease, diabetes mellitus and obesity increase the risk of severe complications of COVID-19. There is no certain explanation for this systemic COVID-19 involvement, but it could be related to endothelial dysfunction, due to direct (endothelial cells are infected by the virus) and indirect damage (systemic inflammation) factors. Angiotensin-converting enzyme 2 (ACE2), expressed in human endothelium, has a fundamental role in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In fact, ACE2 is used as a receptor by SARS-CoV-2, leading to the downregulation of these receptors on endothelial cells; once inside, this virus reduces the integrity of endothelial tissue, with exposure of prothrombotic molecules, platelet adhesion, activation of coagulation cascades and, consequently, vascular damage. Systemic microangiopathy and thromboembolism can lead to multi-organ failure with an elevated risk of death. Considering the crucial role of the immunological response and endothelial damage in developing the severe form of COVID-19, in this review, we will attempt to clarify the underlying pathophysiological mechanisms.

Selenium deficiency aggravates bisphenol A-induced autophagy in chicken kidney through regulation of nitric oxide and adenosine monophosphate activated protein kinase/mammalian target of rapamycin signaling pathway

Bisphenol A (BPA), a phenolic compound, is harmful to humans and animals as its residue in the water threatens multiple organs, especially the kidney. Low selenium (Se) diets are consumed in many regions of the world, and poor Se status has exacerbating effect on toxicity of several environmental chemicals. Here, we described the discovery path of Se deficiency aggravation on autophagy in BPA treated chicken kidney through regulating nitric oxide (NO) and adenosine monophosphate activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathways. The actual dietary Se intake for chickens was 0.30 mg/kg in control group and 0.03 mg/kg in Low-Se group, and BPA exposure concentration for chickens was 0.05 g/kg. Chicken embryo kidney (CEK) cells were used in vitro and the BPA exposure concentration for CEK cells was 150 nM. We found that BPA significantly increased levels of NO and inducible nitric oxide synthase, activated AMPK/mTOR signaling pathways, thereby triggering p62/LC3/Beclin1 signaling, resulting in formations of autophagosome and autolysosome, and finally stimulating autophagy in the chicken kidney. Additionally, Se deficiency promoted the occurrence of autophagy in BPA-treated kidneys. Altogether, our findings showed that Se deficiency exacerbates BPA-induced renal autophagy in chickens via regulation of NO and AMPK/mTOR signaling pathways. These findings will improve our understandings of the mechanisms of nephrotoxicity of BPA and detoxification by Se in chickens. In addition, further work is required to determine if Se status of exposed populations needs to be considered in future epidemiological assessments.

Critical role of nitric oxide in impeding COVID-19 transmission and prevention: a promising possibility

COVID-19 is a serious respiratory infection caused by a beta-coronavirus that is closely linked to SARS. Hypoxemia is a symptom of infection, which is accompanied by acute respiratory distress syndrome (ARDS). Augmenting supplementary oxygen may not always improve oxygen saturation; reversing hypoxemia in COVID-19 necessitates sophisticated means to promote oxygen transfer from alveoli to blood. Inhaled nitric oxide (iNO) has been shown to inhibit the multiplication of the respiratory coronavirus, a property that distinguishes it from other vasodilators. These findings imply that NO may have a crucial role in the therapy of COVID-19, indicating research into optimal methods to restore pulmonary physiology. According to clinical and experimental data, NO is a selective vasodilator proven to restore oxygenation by helping to normalize shunts and ventilation/perfusion mismatches. This study examines the role of NO in COVID-19 in terms of its specific physiological and biochemical properties, as well as the possibility of using inhaled NO as a standard therapy. We have also discussed how NO could be used to prevent and cure COVID-19, in addition to the limitations of NO.

Targeted protein S-nitrosylation of ACE2 as potential treatment to prevent spread of SARS-CoV-2 infection

Prevention of infection and propagation of SARS-CoV-2 is of high priority in the COVID-19 pandemic. Here, we describe S-nitrosylation of multiple proteins involved in SARS-CoV-2 infection, including angiotensin converting enzyme 2 (ACE2), the receptor for viral entry. This reaction prevents binding of ACE2 to the SARS-CoV-2 Spike protein, thereby inhibiting viral entry, infectivity, and cytotoxicity. Aminoadamantane compounds also inhibit coronavirus ion channels formed by envelope (E) protein. Accordingly, we developed dual-mechanism aminoadamantane nitrate compounds that inhibit viral entry and thus spread of infection by S-nitrosylating ACE2 via targeted delivery of the drug after E-protein channel blockade. These non-toxic compounds are active in vitro and in vivo in the Syrian hamster COVID-19 model, and thus provide a novel avenue for therapy.

NO in Viral Infections: Role and Development of Antiviral Therapies

Nitric oxide is a ubiquitous signaling radical that influences critical body functions. Its importance in the cardiovascular system and the innate immune response to bacterial and viral infections has been extensively investigated. The overproduction of NO is an early component of viral infections, including those affecting the respiratory tract. The production of high levels of NO is due to the overexpression of NO biosynthesis by inducible NO synthase (iNOS), which is involved in viral clearance. The development of NO-based antiviral therapies, particularly gaseous NO inhalation and NO-donors, has proven to be an excellent antiviral therapeutic strategy. The aim of this review is to systematically examine the multiple research studies that have been carried out to elucidate the role of NO in viral infections and to comprehensively describe the NO-based antiviral strategies that have been developed thus far. Particular attention has been paid to the potential mechanisms of NO and its clinical use in the prevention and therapy of COVID-19.

Implications of microvascular dysfunction and nitric oxide mediated inflammation in severe COVID-19 infection

Infection with COVID-19 has resulted in over 276,000 deaths in the United States and over 1.5 million deaths globally, with upwards of 15% of patients requiring hospitalization. Severe COVID-19 infection is, in essence, a microvascular disease. This contention has been emphasized throughout the course of the pandemic, particularly due to the clinical manifestation of severe infection. In fact, it has been hypothesized and shown in particular instances that microvascular function is a significant prognosticator for morbidity and mortality. Initially thought to be isolated to the pulmonary system and resulting in ARDS, patients with COVID-19 have been observed to have acute cardiac, renal, and thrombolytic complications. Therefore, severe COVID-19 is a vascular disease that has systemic implications. The objective of this review is to provide a mechanistic background for the microvascular nature of severe COVID-19 infection, with a particular emphasis on dysfunction of the endothelial glycocalyx and nitric oxide mediated pathogenesis.

Nitric Oxide in the Management of Respiratory Consequences in COVID-19: A Scoping Review of a Different Treatment Approach

The severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) virus causing COVID-19 significantly affects the respiratory functions of infected individuals by massively disrupting the pulmonary oxygenation and activating the synthesis of proinflammatory cytokines, inducing severe oxidative stress, enhanced vascular permeability, and endothelial dysfunction which have rendered researchers and clinicians to depend on prophylactic treatment due to the unavailability of proper disease management approaches. Previous studies have indicated that nitric oxide (NO) application appears to be significant concerning the antiviral activities, antioxidant, and anti-inflammatory properties in relieving disease-related symptoms. To identify, explore, and map the literature on the role of nitric oxide in the management of respiratory consequences in COVID-19 through this scoping review, Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed during the search to answer the focal question: "What are the potential uses of nitric oxide in the management of respiratory failure in COVID-19?" Administering exogenous NO in the form of inhaled gas or stimulating the system to produce NO appears to be a suitable option to manage COVID-19-induced pneumonia and respiratory illness. This treatment modality seems to attenuate respiratory distress among patients suffering from severe infections or patients with comorbidities. Exogenous NO at different doses effectively reduces systemic hyperinflammation and oxidative stress, improves arterial oxygenation, and restores pulmonary alveolar cellular integrity to prevent the lungs and other organs from further damage. This therapy could pave the way for better management of COVID-19 before the onset of disease-related complications.

Inducible Nitric Oxide Synthase (iNOS): Why a Different Production in COVID-19 Patients of the Two Waves?

Profound clinical differences between the first and second waves of COVID-19 were observed in Europe. Nitric oxide (NO) may positively impact patients with Severe Acute Respiratory Syndrome CoronaVirus-2 (SARS-CoV-2) infection. It is mainly generated by inducible nitric oxide synthase (iNOS). We studied serum iNOS levels together with serum interleukin (IL)-6 and IL-10 in patients with SARS-CoV-2 infection in the first wave (n = 35) and second wave (n = 153). In the first wave, serum iNOS, IL-6, IL-10 levels increased significantly, in line with the World Health Organization (WHO) score severity, while in the second wave, iNOS did not change with the severity. The patients of the second wave showed lower levels of iNOS, IL-6, and IL-10, as compared to the corresponding subgroup of the first wave, suggesting a less severe outcome of COVID-19 in these patients. However, in the severe patients of the second wave, iNOS levels were significantly lower in patients treated with steroids or azithromycin before the hospitalization, as compared to the untreated patients. This suggests an impairment of the defense mechanism against the virus and NO-based therapies as a potential therapy in patients with low iNOS levels.

SARS-CoV-2 3CLpro whole human proteome cleavage prediction and enrichment/depletion analysis

A novel coronavirus (SARS-CoV-2) has devastated the globe as a pandemic that has killed millions of people. Widespread vaccination is still uncertain, so many scientific efforts have been directed toward discovering antiviral treatments. Many drugs are being investigated to inhibit the coronavirus main protease, 3CLpro, from cleaving its viral polyprotein, but few publications have addressed this protease’s interactions with the host proteome or their probable contribution to virulence. Too few host protein cleavages have been experimentally verified to fully understand 3CLpro’s global effects on relevant cellular pathways and tissues. Here, I set out to determine this protease’s targets and corresponding potential drug targets. Using a neural network trained on cleavages from 392 coronavirus proteomes with a Matthews correlation coefficient of 0.985, I predict that a large proportion of the human proteome is vulnerable to 3CLpro, with 4898 out of approximately 20,000 human proteins containing at least one putative cleavage site. These cleavages are nonrandomly distributed and are enriched in the epithelium along the respiratory tract, brain, testis, plasma, and immune tissues and depleted in olfactory and gustatory receptors despite the prevalence of anosmia and ageusia in COVID-19 patients. Affected cellular pathways include cytoskeleton/motor/cell adhesion proteins, nuclear condensation and other epigenetics, host transcription and RNAi, ribosomal stoichiometry and nascent-chain detection and degradation, ubiquitination, pattern recognition receptors, coagulation, lipoproteins, redox, and apoptosis. This whole proteome cleavage prediction demonstrates the importance of 3CLpro in expected and nontrivial pathways affecting virulence, lead me to propose more than a dozen potential therapeutic targets against coronaviruses, and should therefore be applied to all viral proteases and subsequently experimentally verified.

Initiation of Inhaled Nitric Oxide by Air Transport Team in Adult COVID-19 Respiratory Failure

The coronavirus disease 2019 (COVID-19) pandemic has caused a significant increase in the volume of critical care flight transports between outlying referral hospitals and tertiary care facilities. Because of the tropism of severe acute respiratory syndrome coronavirus 2, flight crews are often asked to transport mechanically ventilated patients in refractory hypoxemic respiratory failure. The authors present a case series of 5 patients with COVID-19 acute respiratory distress syndrome (ARDS) who were initiated on inhaled nitric oxide (iNO) by the transport team before rotor wing transport and survived the journey in stable or improved condition upon arrival. Previously, no case reports have described adults with COVID-19 ARDS transported after iNO initiation by the transport team. This case series shows the feasibility of iNO initiation by trained air medical transport teams and suggests a short-term stabilizing effect of iNO in patients with ARDS from COVID-19.

Modulation of Macrophage Polarization by Viruses: Turning Off/On Host Antiviral Responses

Macrophages are professional antigen-presenting cells and serve as the first line of defense against invading pathogens. Macrophages are polarized toward the proinflammatory classical (M1) or anti-inflammatory alternative (M2) phenotype upon viral infections. M1-polarized macrophages exert critical roles in antiviral responses via different mechanisms. Within the long competitive history between viruses and hosts, viruses have evolved various immune evasion strategies, inhibiting macrophage acquisition of an antiviral phenotype, impairing the antiviral responses of activated macrophages, and/or exploiting macrophage phenotypes for efficient replication. This review focuses on the sophisticated regulation of macrophage polarization utilized by viruses and is expected to provide systematic insights into the regulatory mechanisms of macrophage polarization by viruses and further facilitate the design of therapeutic targets for antivirals.

Polyphosphate in Antiviral Protection: A Polyanionic Inorganic Polymer in the Fight Against Coronavirus SARS-CoV-2 Infection

Polyanions as polymers carrying multiple negative charges have been extensively studied with regard to their potential antiviral activity. Most studies to date focused on organic polyanionic polymers, both natural and synthetic. The inorganic polymer, polyphosphate (polyP), despite the ubiquitous presence of this molecule from bacteria to man, has attracted much less attention. More recently, and accelerated by the search for potential antiviral agents in the fight against the pandemic caused by the coronavirus SARS-CoV-2, it turned out that polyP disrupts the first step of the viral replication cycle, the interaction of the proteins in the virus envelope and in the cell membrane that are involved in the docking process of the virus with the target host cell. Experiments on a molecular level using the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and the cellular angiotensin converting enzyme 2 (ACE2) receptor revealed that polyP strongly inhibits the binding reaction through an electrostatic interaction between the negatively charged centers of the polyP molecule and a cationic groove, which is formed by positively charged amino acids on the RBD surface. In addition, it was found that polyP, due to its morphogenetic and energy delivering activities, enhances the antiviral host innate immunity defense of the respiratory epithelium. The underlying mechanisms and envisaged application of polyP in the therapy and prevention of COVID-19 are discussed.

Repurposing of Hydroxyurea Against COVID-19: A Promising Immunomodulatory Role

Cytokine release syndrome, a prominent mechanism of morbidity and mortality in patients with coronavirus disease 2019 (COVID-19), can cause multiple bodily reactions, including excessive release of proinflammatory mediators, with tumor necrosis factor-α (TNF-α) being the most prevalent cytokine combined with persistently elevated D-dimer levels that are indicative of potential thrombotic events, low levels of endogenous nitric oxide (NO) generation, and progressive decrease in hemoglobin production. In our argument, the conceptual repurposing of hydroxyurea (HU) for managing COVID-19 can provide a promising therapeutic option originating from a rich history of investigational antiviral activity. HU as a proposed supportive therapeutic agent for treating COVID-19 can exemplify a successful remedial choice through its anti-inflammatory activity along with an intrinsic propensity to control the circulatory levels of key cytokines including TNF-α. HU has the ability to undergo in vivo NO conversion acting as NO donor together with being a prominent inducer of fetal hemoglobin (HbF) production. The combination of the mentioned two properties allows HU to possess evident capability of protecting against thrombotic events by controlling D-dimer levels. The implication of our hypothetical argument sheds light on the curative potential of HU, which can be strategically harnessed against COVID-19.

Photoinduced linkage isomers in a model ruthenium nitrosyl complex: Identification and assignment of vibrational modes

Photoinduced NO-linkage isomers were investigated in the solid state of labelled trans-[Ru(^14/15NO)(py₄)F](ClO₄)₂ complex by combined IR-spectroscopy and DFT calculations. Based on the experimental data and the DFT calculations of this isotopically labelled ^14/15NO nitrosyl compound, we present a complete assignment of the vibrational bands of three nitrosyl linkage isomers in a range from 4000 to 200 cm^-1. The calculated IR-spectra match well with the experimental data allowing reliable assignment of the vibrational bands. The structural change from the Ru-NO (GS) to the Ru-ON (MS1) and Ru-η²-(NO) (MS2) linkage configuration leads to the downshift of the ν(NO) and ν(Ru-(NO)) bands, and a corresponding increase of the energy of the ν(Ru-F) band. The shift of the bands corresponds to the change of the Ru-(NO) and Ru-F bond lengths: increase of the Ru-(NO) bond length leads to the decrease of the energy of the ν(Ru-(NO)) band; decrease of the Ru-F bond length leads to the increase of the energy of the ν(Ru-F) band. These observations can be extrapolated to the family of related nitrosyl complexes and therefore be used for the qualitative prediction of the Ru-(NO) and Ru-L_trans-to-NO bond lengths of different linkage isomers in the framework of one complex. While the formation of linkage isomers is a reversible process, long-time irradiation sometimes induces irreversible reactions such as the release of NO. Here, we show that the photolysis of trans-[Ru(^14/15NO)(py₄)F](ClO₄)₂ in KBr pellets may lead to the release of nitrous oxide N₂O, conceivably through the formation of a {Ru-(κ²-ONNO)} intermediate.

Roles of Nitric Oxide in the Regulation of Reproduction: A Review

Nitric oxide (NO) has attracted significant attention as a stellar molecule. Presently, the study of NO has penetrated every field of life science, and NO is widely distributed in various tissues and organs. This review demonstrates the importance of NO in both male and female reproductive processes in numerous ways, such as in neuromodulation, follicular and oocyte maturation, ovulation, corpus luteum degeneration, fertilization, implantation, pregnancy maintenance, labor and menstrual cycle regulation, spermatogenesis, sperm maturation, and reproduction. However, the mechanism of action of some NO is still unknown, and understanding its mechanism may contribute to the clinical treatment of some reproductive diseases.

The nano-based theranostics for respiratory complications of COVID-19

High morbidity and mortality caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has made coronavirus disease 2019 (COVID-19) the leading challenge for health experts all over the world. Currently, there is no specific treatment for COVID-19; however, thanks to worldwide intense attempts, novel vaccines such as mRNA-1273 (Moderna TX, Inc.) and BNT162b2 (Biontech/Pfizer) were developed very fast and FDA approved them for emergency use. Nanomedicine-based drug delivery can be an advanced therapeutic strategy to deal with clinical complications of COVID-19. Given the fact that SARS-CoV-2 typically affects the respiratory tract, application of inhalable nanoparticles (NPs) for targeted drug delivery to the alveolar space appears to be an effective and promising therapeutic strategy. Loading the medicinal components into NPs enhances the stability, bioavailability, solubility and sustained release of them. This approach can circumvent major challenges in efficient drug delivery such as solubility and any adverse impact of medicinal components due to off-targeted delivery and resulting systemic complications. Inhalable NPs could be delivered through nasal sprays, inhalers, and nebulizers. NPs also could interfere in virus attachment to host cells and prevent infection. Moreover, nanomedicine-based technologies can facilitate accurate and rapid detection of virus compared to the conventional methods. In this review, the nano-based theranostics modalities for the management of respiratory complications of COVID-19 were discussed.

Emerging nanomaterials applied for tackling the COVID-19 cytokine storm

During the global outbreak of coronavirus disease 2019 (COVID-19), a hyperinflammatory state called the cytokine storm was recognized as a major contributor to multiple organ failure and mortality. However, to date, the diagnosis and treatment of the cytokine storm remain major challenges for the clinical prognosis of COVID-19. In this review, we outline various nanomaterial-based strategies for preventing the COVID-19 cytokine storm. We highlight the contribution of nanomaterials to directly inhibit cytokine release. We then discuss how nanomaterials can be used to deliver anti-inflammatory drugs to calm the cytokine storm. Nanomaterials also play crucial roles in diagnostics. Nanomaterial-based biosensors with improved sensitivity and specificity can be used to detect cytokines. In summary, emerging nanomaterials offer platforms and tools for the detection and treatment of the COVID-19 cytokine storm and future pandemic.

Organosilica colloids as nitric oxide carriers: Pharmacokinetics and biocompatibility

Nitric oxide (NO) is a potential therapeutic agent for various diseases. However, it is challenging to deliver this unstable, free-radical gaseous molecule in the body. Various nanoparticle-based drug delivery systems have been investigated as promising NO carriers without detailed characterization of their biological fate. The purpose of this study is to investigate the pharmacokinetics and biocompatibility of organosilica-based NO-delivering nanocarriers. Two distinct NO nanoformulations, namely NO-SiNP-1 and NO-SiNP-2, were prepared from a thiol-functionalized organosilane using nanoprecipitation and direct aqueous synthesis, respectively. During the preparation, the thiol group was converted to S-nitrosothiol (SNO) under a nitrosation condition. The final products contain SNO-loaded organosilica particles of similar sizes (~130 nm), but of different morphologies and surface charges (between the two formulations). In the in vitro release kinetics study, NO-SiNP-1 exhibited a much slower NO release rate than NO-SiNP-2 (by 5-fold); therefore, the former is considered as a slow NO releaser, and the latter a fast NO releaser. However, in the rat pharmacokinetic study (IV bolus of 50 μmol/kg), NO-SiNP-1 was rapidly eliminated from the blood (within 20 min); in contrast, NO-SiNP-2 was slowly eliminated with an extended circulation time of 12 h for plasma SNO, along with markedly higher plasma levels of nitrite and nitrate. The two formulations are generally biocompatible. In conclusion, the paper presents contrast biological fates of two organosilica colloidal formulations for nitric oxide delivery.

Nitric oxide release and related light-induced cytotoxicity of ruthenium nitrosyls with coordinated nicotinate derivatives

The synthetic approaches for the preparation of trans(NO,OH)-cis(NO₂,NO₂)-[RuNO(L)₂(NO₂)₂OH], where L = ethyl nicotinate (I) and methyl nicotinate (II), are reported. The structures of the complexes are characterized by X-ray diffraction and analyzed by Hirshfeld surface analysis. Both compounds show a nitric oxide release reaction under 445 or 532 nm irradiation of dimethyl sulfoxide (DMSO) solutions, which is studied by combined ultraviolet-visible- (UV-vis), infrared- (IR), and electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations. The charge transfer from the OH-Ru-NO chain and nitrite ligands to the antibonding orbitals of Ru-NO is responsible for the photo-cleavage of the ruthenium-nitrosyl bond. The elimination of NO leads to a side reaction, namely the protonation of the parent hydroxyl compound. The cytotoxicity and photo-induced cytotoxicity investigations of both compounds on the breast adenocarcinoma cell line MCF-7 reveal that (I) and (II) are cytotoxic with IC₅₀ values of 27.5 ± 2.8 μM and 23.3 ± 0.3 μM, respectively. Moreover, (I) shows an increase of the toxicity after light irradiation by 7 times (IC₅₀ = 4.1 ± 0.1), which makes it a prominent target for deeper biological investigations.

Emerging nanotechnology role in the development of innovative solutions against COVID-19 pandemic

The COVID-19 outbreak is creating severe impressions on all facets of the global community. Despite strong measures worldwide to try and re-achieve normalcy, the ability of SARS-CoV-2 to survive sturdy ecological settings may contribute to its rapid spread. Scientists from different aspects of life are working together to develop effective treatment strategies against SARS-CoV-2. Apart from using clinical devices for patient recovery, the key focus is on developing antiviral drugs and vaccines. Given the physical size of the SARS-CoV-2 pathogen and with the vaccine delivery platform currently undergoing clinical trials, the link between nanotechnology is clear, and previous antiviral research using nanomaterials confirms this link. Nanotechnology based products can effectively suppress various pathogens, including viruses, regardless of drug resistance, biological structure, or physiology. Thus, nanotechnology is opening up new dimensions for developing new strategies for diagnosing, preventing, treating COVID-19 and other viral ailments. This article describes the application of nanotechnology against the COVID-19 virus in terms of therapeutic purposes and vaccine development through the invention of nanomaterial based substances such as sanitizers (handwashing agents and surface disinfectants), masks and gowns, amongst other personal protective equipment, diagnostic tools, and nanocarrier systems, as well as the drawbacks and challenges of nanotechnology that need to be addressed.

Therapeutic approaches in COVID-19 followed before arrival of any vaccine

In present times covid-19 is spreading and is showing very destructive effects. It does not only affected the physical health but mental health as well as the economy of the major affected countries. Corona viruses are group of related RNA viruses. The first case of this virus was observed in China and then this virus got spread in the many countries and different strategies were made to stop the spread of this virus. Since no particular vaccine was available to cure this so different strategies were made. Due to the emergence of pandemic diseases, drug development and control strategies have been re-examined. One of the most important factors that scientists have to consider is the effectiveness of their drugs. This virus causes the respiratory tract infections which can range from mild to lethal. COVID-19 is a major cause of death in advanced countries. It is due to the absence of any particular vaccine that can effectively treat this condition. So in this review we will discuss about the therapeutic approaches followed to combat this deadly virus. Ayurveda, nitric oxide, nanoparticles and enzymes played a very important role in boosting the immunity and treatment of corona. Many herbs and some tips of using a combination of herbs proved to be very efficient while facing problems in breathing. Giving the dose of nitric oxide at some particular level and chloroquine the drug showed the antiviral activity against the virus. Developing methods to identify and contain COVID-19 is essential to successfully manage the virus. Various strains of the SARS-COV-2 were detected and were found more dangerous. The therapeutic approaches followed actually were efficient and can be used to combat the other variants also. This review focuses on the latest developments in the field of therapeutics and the strategies which were followed before any vaccine.

Persistent Right Ventricle Dilatation in SARS-CoV-2-Related Acute Respiratory Distress Syndrome on Extracorporeal Membrane Oxygenation Support

Objectives

Venovenous extracorporeal membrane oxygenation (ECMO) support may be considered in experienced centers for patients with acute respiratory distress syndrome (ARDS) due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection refractory to conventional treatment. In ECMO patients, echocardiography has emerged as a clinical tool for implantation and clinical management; but to date, little data are available on COVID-related ARDS patients requiring ECMO. The authors assessed the incidence of right ventricular dilatation and dysfunction (RvDys) in patients with COVID-related ARDS requiring ECMO.

Design

Single-center investigation.

Setting

Intensive care unit (ICU).

Participants

A total of 35 patients with COVID-related ARDS requiring ECMO, consecutively admitted to the ICU (March 1, 2020, to February 28, 2021).

Interventions

Serial echocardiographic examinations. RvDys was defined as RV end-diastolic area/LV end-diastolic area >0.6 and tricuspid annular plane excursion <15 mm.

Measurements and Main Results

The incidence of RvDys was 15/35 (42%). RvDys patients underwent ECMO support after a longer period of mechanical ventilation (p = 0.006) and exhibited a higher mortality rate (p = 0.024) than those without RvDys. In nonsurvivors, RvDys was observed in all patients (n = nine) who died with unfavorable progression of COVID-related ARDS. In survivors, weaned from ECMO, a significant reduction in systolic pulmonary arterial pressures was detectable.

Conclusions

According to the authors’ data, in COVID-related ARDS requiring ECMO support, RvDys is common, associated with increased ICU mortality. Overall, the data underscored the clinical role of echocardiography in COVID-related ARDS supported by venovenous ECMO, because serial echocardiographic assessments (especially focused on RV changes) are able to reflect pulmonary COVID disease severity.

Cardiovascular Disease Complicating COVID-19 in the Elderly

SARS-CoV-2, a single-stranded RNA coronavirus, causes an illness known as coronavirus disease 2019 (COVID-19). The highly transmissible virus gains entry into human cells primarily by the binding of its spike protein to the angiotensin-converting enzyme 2 receptor, which is expressed not only in lung tissue but also in cardiac myocytes and the vascular endothelium. Cardiovascular complications are frequent in patients with COVID-19 and may be a result of viral-associated systemic and cardiac inflammation or may arise from a virus-induced hypercoagulable state. This prothrombotic state is marked by endothelial dysfunction and platelet activation in both macrovasculature and microvasculature. In patients with subclinical atherosclerosis, COVID-19 may incite atherosclerotic plaque disruption and coronary thrombosis. Hypertension and obesity are common comorbidities in COVID-19 patients that may significantly raise the risk of mortality. Sedentary behaviors, poor diet, and increased use of tobacco and alcohol, associated with prolonged stay-at-home restrictions, may promote thrombosis, while depressed mood due to social isolation can exacerbate poor self-care. Telehealth interventions via smartphone applications and other technologies that document nutrition and offer exercise programs and social connections can be used to mitigate some of the potential damage to heart health.

The Role of Alveolar Edema in COVID-19

The coronavirus disease 2019 (COVID-19) has spread over the world for more than one year. COVID-19 often develops life-threatening hypoxemia. Endothelial injury caused by the viral infection leads to intravascular coagulation and ventilation-perfusion mismatch. However, besides above pathogenic mechanisms, the role of alveolar edema in the disease progression has not been discussed comprehensively. Since the exudation of pulmonary edema fluid was extremely serious in COVID-19 patients, we bring out a hypothesis that severity of alveolar edema may determine the size of poorly-ventilated area and the blood oxygen content. Treatments to pulmonary edema (conservative fluid management, exogenous surfactant replacements and ethanol–oxygen vapor therapy hypothetically) may be greatly helpful for reducing the occurrences of severe cases. Given that late mechanical ventilation may cause mucus (edema fluid) to be blown deep into the small airways, oxygen therapy should be given at the early stages. The optimal time and blood oxygen saturation (SpO₂) threshold for oxygen therapy are also discussed.

Efficacy and safety of inhaled nitric oxide in the treatment of severe/critical COVID-19 patients: A systematic review

OBJECTIVE:

Present systematic review aimed to analyze the effect of inhaled nitric oxide (iNO) in the treatment of severe COVID-19 and to compare it to standard of care (SOC), antiviral medications, and other medicines.

MATERIALS AND METHODS:

Medline (PubMed), Scopus, Embase, Ovid, Web of Science, Science Direct, Wiley Online Library, BioRxiv and MedRxiv, and Cochrane (up to April 20, 2021) were the search databases. Two reviewers (SK and CK) independently selected the electronic published literature that studied the effect of nitric oxide with SOC or control. The clinical and physiological outcomes such as prevention of progressive systemic de-oxygenation/clinical improvement, mortality, duration of mechanical ventilation, improvement in pulmonary arterial pressure, and adverse events were assessed.

RESULTS:

The 14 retrospective/protective studies randomly assigning 423 patients met the inclusion criteria. Cumulative study of the selected articles showed that iNO has a mild impact on ventilation time or ventilator-free days. iNO has increased the partial pressure of oxygen/fraction of inspired oxygen ratio of fraction of inspired oxygen in a few patients as compared to baseline. However, in most of the studies, it does not have better outcome when compared to the baseline improvement.

CONCLUSIONS:

In patients with COVID-19 with acute respiratory distress syndrome, nitric oxide is linked to a slight increase in oxygenation but has no effect on mortality.

Kynurenic acid may underlie sex-specific immune responses to COVID-19

Males and females have different immune responses to SARS-CoV-2 infection, with male sex being a risk factor for mortality, particularly among older individuals. Cai et al. performed metabolomics analysis of serum from COVID-19 patients and uninfected health care workers and identified 17 metabolites that were associated with the disease. However, in male COVID-19 patients only, the amount of the tryptophan metabolite kynurenic acid (KA) correlated with age, inflammation, and disease outcome. KA inhibits glutamate release, and glutamate abundance was reduced in patients who deteriorated. Together, these findings indicate that KA is associated with sex-specific differences in immune responses to COVID-19, suggesting that it might be targeted in male patients.

Coronavirus disease 2019 (COVID-19) has poorer clinical outcomes in males than in females, and immune responses underlie these sex-related differences. Because immune responses are, in part, regulated by metabolites, we examined the serum metabolomes of COVID-19 patients. In male patients, kynurenic acid (KA) and a high KA–to–kynurenine (K) ratio (KA:K) positively correlated with age and with inflammatory cytokines and chemokines and negatively correlated with T cell responses. Males that clinically deteriorated had a higher KA:K than those that stabilized. KA inhibits glutamate release, and glutamate abundance was lower in patients that clinically deteriorated and correlated with immune responses. Analysis of data from the Genotype-Tissue Expression (GTEx) project revealed that the expression of the gene encoding the enzyme that produces KA, kynurenine aminotransferase, correlated with cytokine abundance and activation of immune responses in older males. This study reveals that KA has a sex-specific link to immune responses and clinical outcomes in COVID-19, suggesting a positive feedback between metabolites and immune responses in males.

Boosting nitric oxide in stress and respiratory infection: Potential relevance for asthma and COVID-19

Nitric oxide (NO) is a ubiquitous signaling molecule that is critical for supporting a plethora of processes in biological organisms. Among these, its role in the innate immune system as a first line of defense against pathogens has received less attention. In asthma, levels of exhaled NO have been utilized as a window into airway inflammation caused by allergic processes. However, respiratory infections count among the most important triggers of disease exacerbations. Among the multitude of factors that affect NO levels are psychological processes. In particular, longer lasting states of psychological stress and depression have been shown to attenuate NO production. The novel SARS-CoV-2 virus, which has caused a pandemic, and with that, sustained levels of psychological stress globally, also adversely affects NO signaling. We review evidence on the role of NO in respiratory infection, including COVID-19, and stress, and argue that boosting NO bioavailability may be beneficial in protection from infections, thus benefitting individuals who suffer from stress in asthma or SARS-CoV-2 infection.

Structural and Photodynamic Studies on Nitrosylruthenium-Complexed Serum Albumin as a Delivery System for Controlled Nitric Oxide Release

How to deliver nitric oxide (NO) to a physiological target and control its release quantitatively is a key issue for biomedical applications. Here, a water-soluble nitrosylruthenium complex, [(CH₃)₄N][RuCl₃(5cqn)(NO)] (H5cqn = 5-chloro-8-quinoline), was synthesized, and its structure was confirmed with ¹H NMR and X-ray crystal diffraction. Photoinduced NO release was investigated with time-resolved Fourier transform infrared and electron paramagnetic resonance (EPR) spectroscopies. The binding constant of the [RuCl₃(5cqn)(NO)]^- complex with human serum albumin (HSA) was determined by fluorescence spectroscopy, and the binding mode was identified by X-ray crystallography of the HSA and Ru-NO complex adduct. The crystal structure reveals that two molecules of the Ru-NO complex are located in the subdomain IB, which is one of the major drug binding regions of HSA. The chemical structures of the Ru complexes were [RuCl₃(5cqn)(NO)]^- and [RuCl₃(Glycerin)NO]^-, in which the electron densities for all ligands to Ru are unambiguously identified. EPR spin-trapping data showed that photoirradiation triggered NO radical generation from the HSA complex adduct. Moreover, the near-infrared image of exogenous NO from the nitrosylruthenium complex in living cells was observed using a NO-selective fluorescent probe. This study provides a strategy to design an appropriate delivery system to transport NO and metallodrugs in vivo for potential applications.

The Notch Pathway: A Link Between COVID-19 Pathophysiology and Its Cardiovascular Complications

COVID-19 is associated with a large number of cardiovascular sequelae, including dysrhythmias, myocardial injury, myocarditis and thrombosis. The Notch pathway is one likely culprit leading to these complications due to its direct role in viral entry, inflammation and coagulation processes, all shown to be key parts of COVID-19 pathogenesis. This review highlights links between the pathophysiology of SARS-CoV2 and the Notch signaling pathway that serve as primary drivers of the cardiovascular complications seen in COVID-19 patients.

Endothelial cell dysfunction, coagulation, and angiogenesis in coronavirus disease 2019 (COVID-19)

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been led to a pandemic emergency. So far, different pathological pathways for SARS-CoV-2 infection have been introduced in which the excess release of pro-inflammatory cytokines (such as interleukin 1 β [IL-1β], IL-6, and tumor necrosis factor α [TNFα]) has earned most of the attentions. However, recent studies have identified new pathways with at least the same level of importance as cytokine storm in which endothelial cell (EC) dysfunction is one of them. In COVID-19, two main pathologic phenomena have been seen as a result of EC dysfunction: hyper-coagulation state and pathologic angiogenesis. The EC dysfunction-induced hypercoagulation state seems to be caused by alteration in the levels of different factors such as plasminogen activator inhibitor 1 (PAI-1), von Willebrand factor (vWF) antigen, soluble thrombomodulin, and tissue factor pathway inhibitor (TFPI). As data have shown, these thromboembolic events are associated with severity of disease severity or even death in COVID-19 patients. Other than thromboembolic events, pathologic angiogenesis is among the recent findings. Furthermore, over-expression/higher levels of different proangiogenic factors such as vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1 α (HIF-1α), IL-6, TNF receptor super family 1A and 12, and angiotensin-converting enzyme 2 (ACE2) have been found in the lung biopsies/sera of both survived and non-survived COVID-19 patients. Also, there are some hypotheses regarding the role of nitric oxide in EC dysfunction and acute respiratory distress syndrome (ARDS) in SARS-CoV-2 infection. It has been demonstrated that different pathways involved in inflammation are generally common with EC dysfunction and angiogenesis. Altogether, considering the common possible upstream pathways in cytokine storm, pathologic angiogenesis, and EC dysfunction, it seems that targeting these molecules (such as nuclear factor κB) could be more effective in the management of patients with COVID-19.

Systemic Perturbations in Amine and Kynurenine Metabolism Associated with Acute SARS-CoV-2 Infection and Inflammatory Cytokine Responses

We performed quantitative metabolic phenotyping of blood plasma in parallel with cytokine/chemokine analysis from participants who were either SARS-CoV-2 (+) (n = 10) or SARS-CoV-2 (-) (n = 49). SARS-CoV-2 positivity was associated with a unique metabolic phenotype and demonstrated a complex systemic response to infection, including severe perturbations in amino acid and kynurenine metabolic pathways. Nine metabolites were elevated in plasma and strongly associated with infection (quinolinic acid, glutamic acid, nicotinic acid, aspartic acid, neopterin, kynurenine, phenylalanine, 3-hydroxykynurenine, and taurine; p < 0.05), while four metabolites were lower in infection (tryptophan, histidine, indole-3-acetic acid, and citrulline; p < 0.05). This signature supports a systemic metabolic phenoconversion following infection, indicating possible neurotoxicity and neurological disruption (elevations of 3-hydroxykynurenine and quinolinic acid) and liver dysfunction (reduction in Fischer's ratio and elevation of taurine). Finally, we report correlations between the key metabolite changes observed in the disease with concentrations of proinflammatory cytokines and chemokines showing strong immunometabolic disorder in response to SARS-CoV-2 infection.

A strange case of severe but fleeting hypoxemia in patient with COVID-19 infection: maybe virus-induced pulmonary Raynaud's phenomenon?

This case-report describes severe acute respiratory failure in a patient with a COVID-19 positive nasopharyngeal swab that spontaneously resolved within a few hours. It is speculated that the virus may have caused a fleeting pulmonary vasospasm.

Novel and Evolving Therapies for COVID-19 Related Pulmonary Complications. Am J Med Sci 2021;361:557-566. [PMID: 33640363 PMCID: PMC7906517 DOI: 10.1016/j.amjms.2021.02.019]

Coronaviruses disease 2019 (COVID-19) is the most crucial threat, the world has ever witnessed. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of this disease pandemic. The World Health Organization has confirmed the continuing epidemic as a worldwide public health crisis. Presently, the research on COVID-19 is even in the primitive stage. Studies on unveiling the natural route of COVID-19 infection and related pathophysiology, the biology of pulmonary airways pose a more rational restorative approach in the management of COVID-19. Thus, based on the existing facts, we methodically reviewed the efforts put forth by various research institutes, pharmaceutical companies and biotechnology firms in pulmonary delivery to prevent and control the COVID-19. This article would be valuable for the healthcare community, which is efficiently dealing with the SARS-CoV-2 crisis.

Therapeutic Potential of Resveratrol in COVID-19-Associated Hemostatic Disorders

Coagulation disorders, endotheliopathy and inflammation are the most common hallmarks in SARS-CoV-2 infection, largely determining COVID-19's outcome and severity. Dysfunctions of endothelial cells and platelets are tightly linked in contributing to the systemic inflammatory response that appears to be both a cause and a consequence of COVID-19-associated coagulation disorders and thrombotic events. Indeed, elevated levels of circulating inflammatory cytokines are often associated with abnormal coagulation parameters in COVID-19 patients. Although treatments with low molecular weight heparin (LMWH) have shown beneficial effects in decreasing patient mortality with severe COVID-19, additional therapeutic strategies are urgently needed. Utilizing the anti-inflammatory and anti-thrombotic properties of natural compounds may provide alternative therapeutic approaches to prevent or reduce the risk factors associated with pre-existing conditions and comorbidities that can worsen COVID-19 patients' outcomes. In this regard, resveratrol, a natural compound found in several plants and fruits such as grapes, blueberries and cranberries, may represent a promising coadjuvant for the prevention and treatment of COVID-19. By virtue of its anti-thrombotic and anti-inflammatory properties, resveratrol would be expected to lower COVID-19-associated mortality, which is well known to be increased by thrombosis and inflammation. This review analyzes and discusses resveratrol's ability to modulate vascular hemostasis at different levels targeting both primary hemostasis (interfering with platelet activation and aggregation) and secondary hemostasis (modulating factors involved in coagulation cascade).