The role of NO in COVID-19 and potential therapeutic strategies

Potential Mechanisms for Organoprotective Effects of Exogenous Nitric Oxide in an Experimental Study

Performing cardiac surgery under cardiopulmonary bypass (CPB) and circulatory arrest (CA) provokes the development of complications caused by tissue metabolism, microcirculatory disorders, and endogenous nitric oxide (NO) deficiency. This study aimed to investigate the potential mechanisms for systemic organoprotective effects of exogenous NO during CPB and CA based on the assessment of dynamic changes in glycocalyx degradation markers, deformation properties of erythrocytes, and tissue metabolism in the experiment. A single-center prospective randomized controlled study was conducted on sheep, n = 24, comprising four groups of six in each. In two groups, NO was delivered at a dose of 80 ppm during CPB ("CPB + NO" group) or CPB and CA ("CPB + CA + NO"). In the "CPB" and "CPB + CA" groups, NO supply was not carried out. NO therapy prevented the deterioration of erythrocyte deformability. It was associated with improved tissue metabolism, lower lactate levels, and higher ATP levels in myocardial and lung tissues. The degree of glycocalyx degradation and endothelial dysfunction, assessed by the concentration of heparan sulfate proteoglycan and asymmetric dimethylarginine, did not change when exogenous NO was supplied. Intraoperative delivery of NO provides systemic organoprotection, which results in reducing the damaging effects of CPB on erythrocyte deformability and maintaining normal functioning of tissue metabolism.

Evaluation of the relationship between serum BDNF concentration and indicators of oxidative stress and inflammation in COVID-19 patients with neurological disorders - a pilot study

INTRODUCTION

The aim of this study was to determine the effect of serum level of brain-derived neurotrophic factor (BDNF) on the development of neurological disorders in COVID-19 patients and the probable role of oxidative stress and inflammation in this phenomenon.

METHODS

The present case-control study included 42 COVID-19 patients referring to Golestan and Sina hospitals of Ahvaz, Iran, for treatment. Patients with (n = 18) and without (n = 24) neurological disorders were allocated into test and control groups, respectively. Following blood sampling, serum isolation was done, and the serum was stored at -80°C until biochemical assessment for measuring BDNF, oxidative stress indices, and inflammatory factors.

RESULTS

Although no significant brain damage was observed in the COVID-19 patients with neurological disorders, the results showed that the serum level of BDNF in the test group increased compared to that in the control group, and this increment was accompanied with increased Tumor Necrosis Factor-alpha (TNF-α) and decreased Interferon gamma (IFN-γ) levels in the serum. Moreover, compared to the control group, patients in the test group had a decreased level of Thiol and an increased level of Malondialdehyde (MDA) in the serum. Furthermore, there was a significant positive correlation between the serum concentration of BDNF and nitric oxide (NO) in the test group.

CONCLUSION

Using over-the-counter (OTC) medicines which include thiol-group-related agents or any other antioxidants can alleviate oxidative stress and the associated increased inflammation in COVID-19 patients with neurological symptoms.

SARS CoV-2 infection screening via the exhaled breath fingerprint obtained by FTIR spectroscopic gas-phase analysis. A proof of concept

The COVID-19 pandemic remains a global challenge now with the long-COVID arising. Mitigation measures focused on case counting, assessment and determination of variants and their likely targets of infection and transmission, the pursuit of drug treatments, use and enhancement of masks, social distancing, vaccination, post-infection rehabilitation, and mass screening. The latter is of utmost importance given the current scenario of infections, reinfections, and long-term health effects. Research on screening platforms has been developed to provide more sensitive, specific, and reliable tests that are accessible to the entire population and can be used to assess the prognosis of the disease as well as the subsequent health follow-up of patients with sequelae of COVID-19. Therefore, the aim of the present study was the simulation of exhaled breath of COVID-19 patients by evaluation of three identified COVID-19 indicator breath biomarkers (acetone (ACE), acetaldehyde (ACH) and nitric oxide (NO)) by gas-phase infrared spectroscopy as a proof-of-concept principle for the detection of infected patients' exhaled breath fingerprint and subsequent follow-up. The specific fingerprints of each of the compounds and the overall fingerprint were obtained. The synthetic exhaled breath evaluation concept revealed a linearity of r = 0.99 for all compounds, and LODs of 6.42, 13.81, 9.22 ppm, and LOQs of 42.26, 52.57, 69.23 ppm for NO, ACE, and ACH, respectively. This study proves the fundamental feasibility of gas-phase infrared spectroscopy for fingerprinting lung damage biomarkers in exhaled breath of patients with COVID-19. This analysis would allow faster and cheaper screening and follow-up of infected individuals, which could improve mass screening in POC settings.

The Association Between Tobacco Use and Risk of COVID-19 Infection and Clinical Outcomes in Sweden: A Population-Based Study

Background: The association between tobacco use and COVID-19 is controversial. During the early course of the pandemic, limited testing prevented studying a wide spectrum of clinical manifestations. Objective: To examine the potential causal association between tobacco use and COVID-19 during the second wave (1 October 2020-30 June 2021) of the pandemic in Stockholm, Sweden. Methods: A population-based cohort study was conducted in the Stockholm region of Sweden, with information on tobacco use collected prior to the pandemic. Adjusted relative risks (RR) of COVID-19 and 95% confidence intervals (CI) were calculated, contrasting current smokers and snus users to non-users of tobacco. Results: Compared with non-users of tobacco, current smokers had a lower risk of COVID-19 (RR 0.78, 95% CI = 0.75-0.81) and of hospitalisation for the disease. Current snus users had a higher risk of COVID-19. Heavy smokers and snus users had longer hospital stays than non-users of tobacco. Conclusion: Tobacco use may have a different impact on the risk of being infected with SARS-CoV-2 and the risk of developing severe clinical manifestations. Further research is needed to determine the underlying mechanisms.

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.

Unravelling the Mystery of COVID-19 Pathogenesis: Spike Protein and Cu Can Synergize to Trigger ROS Production

The COVID-19 pandemic has had a devastating impact on global health, highlighting the need to understand how the SARS-CoV-2 virus damages the lungs in order to develop effective treatments. Recent research has shown that patients with COVID-19 experience severe oxidative damage to various biomolecules. We propose that the overproduction of reactive oxygen species (ROS) in SARS-CoV-2 infection involves an interaction between copper ions and the virus's spike protein. We tested two peptide fragments, Ac-ELDKYFKNH-NH2 (L1) and Ac-WSHPQFEK-NH2 (L2), derived from the spike protein of the Wuhan strain and the β variant, respectively, and found that they bind Cu(II) ions and form a three-nitrogen complexes at lung pH. Our research demonstrates that these complexes trigger the overproduction of ROS, which can break both DNA strands and transform DNA into its linear form. Using A549 cells, we demonstrated that ROS overproduction occurs in the mitochondria, not in the cytoplasm. Our findings highlight the importance of the interaction between copper ions and the virus's spike protein in the development of lung damage and may aid in the development of therapeutic procedures.

In Situ Noninvasive Observation of Nitric Oxide Fluctuation in SARS-CoV-2 Infection In Vivo by Organic Near-Infrared-II Fluorescent Molecular Nanoprobes

The pathogenesis understanding of SARS-CoV-2 infection is crucial to prevent the rampant spread of COVID-19 and its contribution to deterioration in health, even death. Nitric oxide (NO), a crucial molecule involved in signal transduction and cytotoxicity, is a possible key regulator in the occurrence and development of COVID-19. However, understanding the pathogenesis of NO in SARS-CoV-2 infection is still in its infancy due to the lack of suitable in situ monitoring probes of NO fluctuation in the complex SARS-CoV-2 infection environment in deep lung tissues. Herein, we developed an activatable near-infrared-II fluorescent molecular nanoprobe (OSNP) that uncages high-resolution and deep-tissue-penetrating near-infrared-II fluorescence signal in specific response to NO for in situ and noninvasive visualization of NO fluctuation in a SARS-CoV-2 infection mouse model in lung tissues. In vivo visualization revealed that the NO level is a positive relationship with SARS-CoV-2 infection progress. With the assistance of immuno-histochemical analyses, we uncovered the NO-involved pathological mechanism, that being the improved NO level is associated with an increase in inducible NO synthase rather than endothelial NO synthase. Our study not only provides the example of a near-infrared-II fluorescent imaging of NO in SARS-CoV-2 infection but also provides opportunities to uncover tunderlying pathomechanism of NO for SARS-Cov-2 infections.

Immune landscape and redox imbalance during neurological disorders in COVID-19

The outbreak of Coronavirus Disease 2019 (COVID-19) has prompted the scientific community to explore potential treatments or vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the illness. While SARS-CoV-2 is mostly considered a respiratory pathogen, several neurological complications have been reported, raising questions about how it may enter the Central Nervous System (CNS). Receptors such as ACE2, CD147, TMPRSS2, and NRP1 have been identified in brain cells and may be involved in facilitating SARS-CoV-2 entry into the CNS. Moreover, proteins like P2X7 and Panx-1 may contribute to the pathogenesis of COVID-19. Additionally, the role of the immune system in the gravity of COVID-19 has been investigated with respect to both innate and adaptive immune responses caused by SARS-CoV-2 infection, which can lead to a cytokine storm, tissue damage, and neurological manifestations. A redox imbalance has also been linked to the pathogenesis of COVID-19, potentially causing mitochondrial dysfunction, and generating proinflammatory cytokines. This review summarizes different mechanisms of reactive oxygen species and neuro-inflammation that may contribute to the development of severe COVID-19, and recent progress in the study of immunological events and redox imbalance in neurological complications of COVID-19, and the role of bioinformatics in the study of neurological implications of COVID-19.

Clinically Evaluated COVID-19 Drugs with Therapeutic Potential for Biological Warfare Agents

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak resulted in hundreds of millions of coronavirus cases, as well as millions of deaths worldwide. Coronavirus Disease 2019 (COVID-19), the disease resulting from exposure to this pathogen, is characterized, among other features, by a pulmonary pathology, which can progress to "cytokine storm", acute respiratory distress syndrome (ARDS), respiratory failure and death. Vaccines are the unsurpassed strategy for prevention and protection against the SARS-CoV-2 infection. However, there is still an extremely high number of severely ill people from at-risk populations. This may be attributed to waning immune response, variant-induced breakthrough infections, unvaccinated population, etc. It is therefore of high importance to utilize pharmacological-based treatments, despite the progression of the global vaccination campaign. Until the approval of Paxlovid, an efficient and highly selective anti-SARS-CoV-2 drug, and the broad-spectrum antiviral agent Lagevrio, many pharmacological-based countermeasures were, and still are, being evaluated in clinical trials. Some of these are host-directed therapies (HDTs), which modulate the endogenic response against the virus, and therefore may confer efficient protection against a wide array of pathogens. These could potentially include Biological Warfare Agents (BWAs), exposure to which may lead to mass casualties due to disease severity and a possible lack of efficient treatment. In this review, we assessed the recent literature on drugs under advanced clinical evaluation for COVID-19 with broad spectrum activity, including antiviral agents and HDTs, which may be relevant for future coping with BWAs, as well as with other agents, in particular respiratory infections.

A novel insight on SARS-CoV-2 S-derived fragments in the control of the host immunity

Despite all efforts to combat the pandemic of COVID-19, we are still living with high numbers of infected persons, an overburdened health care system, and the lack of an effective and definitive treatment. Understanding the pathophysiology of the disease is crucial for the development of new technologies and therapies for the best clinical management of patients. Since the manipulation of the whole virus requires a structure with an adequate level of biosafety, the development of alternative technologies, such as the synthesis of peptides from viral proteins, is a possible solution to circumvent this problem. In addition, the use and validation of animal models is of extreme importance to screen new drugs and to compress the organism's response to the disease. Peptides derived from recombinant S protein from SARS-CoV-2 were synthesized and validated by in silico, in vitro and in vivo methodologies. Macrophages and neutrophils were challenged with the peptides and the production of inflammatory mediators and activation profile were evaluated. These peptides were also inoculated into the swim bladder of transgenic zebrafish larvae at 6 days post fertilization (dpf) to mimic the inflammatory process triggered by the virus, which was evaluated by confocal microscopy. In addition, toxicity and oxidative stress assays were also developed. In silico and molecular dynamics assays revealed that the peptides bind to the ACE2 receptor stably and interact with receptors and adhesion molecules, such as MHC and TCR, from humans and zebrafish. Macrophages stimulated with one of the peptides showed increased production of NO, TNF-α and CXCL2. Inoculation of the peptides in zebrafish larvae triggered an inflammatory process marked by macrophage recruitment and increased mortality, as well as histopathological changes, similarly to what is observed in individuals with COVID-19. The use of peptides is a valuable alternative for the study of host immune response in the context of COVID-19. The use of zebrafish as an animal model also proved to be appropriate and effective in evaluating the inflammatory process, comparable to humans.

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.

Glutamine Deficiency Promotes Immune and Endothelial Cell Dysfunction in COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has caused the death of almost 7 million people worldwide. While vaccinations and new antiviral drugs have greatly reduced the number of COVID-19 cases, there remains a need for additional therapeutic strategies to combat this deadly disease. Accumulating clinical data have discovered a deficiency of circulating glutamine in patients with COVID-19 that associates with disease severity. Glutamine is a semi-essential amino acid that is metabolized to a plethora of metabolites that serve as central modulators of immune and endothelial cell function. A majority of glutamine is metabolized to glutamate and ammonia by the mitochondrial enzyme glutaminase (GLS). Notably, GLS activity is upregulated in COVID-19, favoring the catabolism of glutamine. This disturbance in glutamine metabolism may provoke immune and endothelial cell dysfunction that contributes to the development of severe infection, inflammation, oxidative stress, vasospasm, and coagulopathy, which leads to vascular occlusion, multi-organ failure, and death. Strategies that restore the plasma concentration of glutamine, its metabolites, and/or its downstream effectors, in conjunction with antiviral drugs, represent a promising therapeutic approach that may restore immune and endothelial cell function and prevent the development of occlusive vascular disease in patients stricken with COVID-19.

Endothelial dysfunction in COVID-19: an overview of evidence, biomarkers, mechanisms and potential therapies

The fight against coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection is still raging. However, the pathophysiology of acute and post-acute manifestations of COVID-19 (long COVID-19) is understudied. Endothelial cells are sentinels lining the innermost layer of blood vessel that gatekeep micro- and macro-vascular health by sensing pathogen/danger signals and secreting vasoactive molecules. SARS-CoV-2 infection primarily affects the pulmonary system, but accumulating evidence suggests that it also affects the pan-vasculature in the extrapulmonary systems by directly (via virus infection) or indirectly (via cytokine storm), causing endothelial dysfunction (endotheliitis, endothelialitis and endotheliopathy) and multi-organ injury. Mounting evidence suggests that SARS-CoV-2 infection leads to multiple instances of endothelial dysfunction, including reduced nitric oxide (NO) bioavailability, oxidative stress, endothelial injury, glycocalyx/barrier disruption, hyperpermeability, inflammation/leukocyte adhesion, senescence, endothelial-to-mesenchymal transition (EndoMT), hypercoagulability, thrombosis and many others. Thus, COVID-19 is deemed as a (micro)vascular and endothelial disease. Of translational relevance, several candidate drugs which are endothelial protective have been shown to improve clinical manifestations of COVID-19 patients. The purpose of this review is to provide a latest summary of biomarkers associated with endothelial cell activation in COVID-19 and offer mechanistic insights into the molecular basis of endothelial activation/dysfunction in macro- and micro-vasculature of COVID-19 patients. We envisage further development of cellular models and suitable animal models mimicking endothelial dysfunction aspect of COVID-19 being able to accelerate the discovery of new drugs targeting endothelial dysfunction in pan-vasculature from COVID-19 patients.

Hematological, Inflammatory, Coagulation, and Oxidative/Antioxidant Biomarkers as Predictors for Severity and Mortality in COVID-19: A Prospective Cohort-Study

Purpose

Oxidative stress (OS) and inflammation are pivotal points in the pathophysiology of coronavirus disease-2019 (COVID-19). This study aims to use routine laboratory and oxidative stress/antioxidative biomarkers as predictors for the mortality of the disease.

Patients and Methods

This prospective cohort study, made up of 120 COVID-19 patients from emergency units in Erbil, Duhok, Kirkuk, and Sulaymaniyah cities in Iraq, from May the 1^st to May the 30^th, 2021, and 60 healthy controls (HCs) (n = 60). The patients were re-categorized into mild (n = 54), severe (n = 40), and critical (n = 26) groups based on the clinical criteria. Following admission to the hospital, blood was directly collected for measuring routine laboratory biomarkers.

Results

Neutrophils and neutrophil/lymphocyte ratio (NLR) were higher in the critical group, while lymphocytes were lower in the severe and critical groups compared to the mild group. The CRP, ferritin, and D-dimer values were more elevated in severe and critical cases than in mild COVID-19 cases. The levels of malondialdehyde (MDA), nitric oxide (NO), and copper were elevated, while the superoxide dismutase (SOD) activity level and total antioxidant capacity (TAC) level were lower. However, vitamin C, glutathione peroxidase (GPx), and catalase activity levels were not changed in the COVID-19 groups compared to the HCs. NO and ferritin were predictors of ICU hospitalization; D-dimer, MDA, and NLR were predictors of mortality. NO, and NLR were predictors of SpO₂ depression. Moreover, NO, and copper have both good diagnostic values, their cutoffs were 39.01 and 11.93, respectively.

Conclusion

There is an association between immune dysregulation and oxidative imbalance. The biomarkers, that could be considered as predictors for the severity and mortality of COVID-19, are the NLR, NO, ferritin, and D-dimer. The age equal to and older than 50 has a poor prognosis in the Kurdish population.

Regulation of pleiotropic physiological roles of nitric oxide signaling

Nitric Oxide (NO) is a highly diffusible, ubiquitous signaling molecule and a free radical that is naturally synthesized by our body. The pleiotropic effects of NO in biological systems are due to its reactivity with different molecules, such as molecular oxygen (O₂), superoxide anion, DNA, lipids, and proteins. There are several contradictory findings in the literature pertaining to its role in oncology. NO is a Janus-faced molecule shown to have both tumor promoting and tumoricidal effects, which depend on its concentration, duration of exposure, and location. A high concentration is shown to have cytotoxic effects by triggering apoptosis, and at a low concentration, NO promotes angiogenesis, metastasis, and tumor progression. Upregulated NO synthesis has been implicated as a causal factor in several pathophysiological conditions including cancer. This dichotomous effect makes it highly challenging to discover its true potential in cancer biology. Understanding the mechanisms by which NO acts in different cancers helps to develop NO based therapeutic strategies for cancer treatment. This review addresses the physiological role of this molecule, with a focus on its bimodal action in various types of cancers.

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.

Molecular signatures in the progression of COVID-19 severity

SARS-CoV-2 is the causative agent of COVID-19 that has infected over 642 million and killed over 6.6 million people around the globe. Underlying a wide range of clinical manifestations of this disease, from moderate to extremely severe systemic conditions, could be genes or pathways differentially expressing in the hosts. It is therefore important to gain insights into pathways involved in COVID-19 pathogenesis and host defense and thus understand the host response to this pathogen at the physiological and molecular level. To uncover genes and pathways involved in the differential clinical manifestations of this disease, we developed a novel gene co-expression network based pipeline that uses gene expression obtained from different SARS-CoV-2 infected human tissues. We leveraged the network to identify novel genes or pathways that likely differentially express and could be physiologically significant in the COVID-19 pathogenesis and progression but were deemed statistically non-significant and therefore not further investigated in the original studies. Our network-based approach aided in the identification of co-expression modules enriched in differentially expressing genes (DEGs) during different stages of COVID-19 and enabled discovery of novel genes involved in the COVID-19 pathogenesis, by virtue of their transcript abundance and association with genes expressing differentially in modules enriched in DEGs. We further prioritized by considering only those enriched gene modules that have most of their genes differentially expressed, inferred by the original studies or this study, and document here 7 novel genes potentially involved in moderate, 2 in severe, 48 in extremely severe COVID-19, and 96 novel genes involved in the progression of COVID-19 from severe to extremely severe conditions. Our study shines a new light on genes and their networks (modules) that drive the progression of COVID-19 from moderate to extremely severe condition. These findings could aid development of new therapeutics to combat COVID-19.

Nitric Oxide and its Derivatives Containing Nasal Spray and Inhalation Therapy for the Treatment of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a major health concern worldwide and has evolved into different variants. SARS-CoV-2 possesses a spike glycoprotein on its envelope that binds to the angiotensin-converting enzyme 2 (ACE-2) receptor of the host cell via the receptor-binding domain (RBD) in the upper respiratory tract. Since the SARS-CoV-2 virus variants change the severity of the diesease and treatment scenarios, repurposing current medicines may provide a quick and appealing method with established safety features. The efficacy and safety of antiviral medicines against the coronavirus disease 2019 (COVID-19) have been investigated, and several of them are now undergoing clinical studies. Recently, it has been found that nitric oxide (NO) shows antiviral properties against SARS-CoV-2 and prevents the virus from binding to a host cell. In addition, NO is a well-known vasodilator and acts as an important coagulation mediator. With the fast-track development of COVID-19 treatments and vaccines, one avenue of research aimed at improving therapeutics is exploring different forms of drug delivery, including intranasal sprays and inhalation therapy. The nasal mucosa is more prone to be the site of infection as it is in more direct contact with the physical environment via air during inhalation and exhalation. Thus, the use of exogenous nasal NO therapy via the intranasal route displays a distinct advantage. Therefore, the objective of this review is to summarize the relevant actions of NO via the intranasal spray and inhalation delivery, its mechanism of action, and its use in the treatment of COVID-19.

Effects of rescue inhaled nitric oxide on right ventricle and pulmonary circulation in severe COVID-related acute respiratory distress syndrome

PURPOSES

To assess the effects of inhaled Nitric Oxide (iNO) on right ventricle dimension and function and systolic pulmonary arterial pressures in severe Acute Respiratory Distress (ARDS) due to Sars-Cov2 (COVID) infection.

MATERIALS AND METHODS

We assessed the effects of iNO on right ventricle dimension and function and systolic pulmonary arterial pressures in 12 consecutive COVID-related ARDS patients by means of serial echocardiographic exams (baseline, 12 and 24 h since iNO start).

RESULTS

Inhaled NO administration did not influence systolic pulmonary arterial pressures nor RV dimension and function. No changes were detectable in ventilatory data with iNO administration. Considering the negligible effect on oxygenation, iNO use was discontinued in all cases.

CONCLUSIONS

In COVID-related severe ARDS iNO administrated as rescue therapy is not able to ameliorate oxygenation nor pulmonary hypertension, as assessed by serial echocardiograms. This finding may be explained by the diffuse loss of hypoxic pulmonary vasoconstriction with increased perfusion around alveolar consolidations which characterizes COVID-related severe ARDS.

Utility of NO and H2S donating platforms in managing COVID-19: Rationale and promise

Viral infections are a continuing global burden on the human population, underscored by the ramifications of the COVID-19 pandemic. Current treatment options and supportive therapies for many viral infections are relatively limited, indicating a need for alternative therapeutic approaches. Virus-induced damage occurs through direct infection of host cells and inflammation-related changes. Severe cases of certain viral infections, including COVID-19, can lead to a hyperinflammatory response termed cytokine storm, resulting in extensive endothelial damage, thrombosis, respiratory failure, and death. Therapies targeting these complications are crucial in addition to antiviral therapies. Nitric oxide and hydrogen sulfide are two endogenous gasotransmitters that have emerged as key signaling molecules with a broad range of antiviral actions in addition to having anti-inflammatory properties and protective functions in the vasculature and respiratory system. The enhancement of endogenous nitric oxide and hydrogen sulfide levels thus holds promise for managing both early-stage and later-stage viral infections, including SARS-CoV-2. Using SARS-CoV-2 as a model for similar viral infections, here we explore the current evidence regarding nitric oxide and hydrogen sulfide's use to limit viral infection, resolve inflammation, and reduce vascular and pulmonary damage.

Ginkgo biloba in the management of the COVID-19 severity

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is linked with inflammatory disorders and the development of oxidative stress in extreme cases. Therefore, anti-inflammatory and antioxidant drugs may alleviate these complications. Ginkgo biloba L. folium extract (EGb) is a herbal medicine containing various active constituents. This review aims to provide a critical discussion on the potential role of EGb in the management of coronavirus disease 2019 (COVID-19). The antiviral effect of EGb is mediated by different mechanisms, including blocking SARS-CoV-2 3-chymotrypsin-like protease that provides trans-variant effectiveness. Moreover, EGb impedes the development of pulmonary inflammatory disorders through the diminution of neutrophil elastase activity, the release of proinflammatory cytokines, platelet aggregation, and thrombosis. Thus, EGb can attenuate the acute lung injury and acute respiratory distress syndrome in COVID-19. In conclusion, EGb offers the potential of being used as adjuvant antiviral and symptomatic therapy. Nanosystems enabling targeted delivery, personalization, and booster of effects provide the opportunity for the use of EGb in modern phytotherapy.

Redox imbalance in COVID-19 pathophysiology

Background

The pathophysiologic significance of redox imbalance is unquestionable as numerous reports and topic reviews indicate alterations in redox parameters during corona virus disease 2019 (COVID-19). However, a more comprehensive understanding of redox-related parameters in the context of COVID-19-mediated inflammation and pathophysiology is required.

Methods

COVID-19 subjects (n = 64) and control subjects (n = 19) were enrolled, and blood was drawn within 72 h of diagnosis. Serum multiplex assays and peripheral blood mRNA sequencing was performed. Oxidant/free radical (electron paramagnetic resonance (EPR) spectroscopy, nitrite-nitrate assay) and antioxidant (ferrous reducing ability of serum assay and high-performance liquid chromatography) were performed. Multivariate analyses were performed to evaluate potential of indicated parameters to predict clinical outcome.

Results

Significantly greater levels of multiple inflammatory and vascular markers were quantified in the subjects admitted to the ICU compared to non-ICU subjects. Gene set enrichment analyses indicated significant enhancement of oxidant related pathways and biochemical assays confirmed a significant increase in free radical production and uric acid reduction in COVID-19 subjects. Multivariate analyses confirmed a positive association between serum levels of VCAM-1, ICAM-1 and a negative association between the abundance of one electron oxidants (detected by ascorbate radical formation) and mortality in COVID subjects while IL-17c and TSLP levels predicted need for intensive care in COVID-19 subjects.

Conclusion

Herein we demonstrate a significant redox imbalance during COVID-19 infection affirming the potential for manipulation of oxidative stress pathways as a new therapeutic strategy COVID-19. However, further work is requisite for detailed identification of oxidants (O₂^•-, H₂O₂ and/or circulating transition metals such as Fe or Cu) contributing to this imbalance to avoid the repetition of failures using non-specific antioxidant supplementation.

The role of platelets, neutrophils and endothelium in COVID-19 infection

INTRODUCTION

COVID-19 is associated to an increased risk of thrombosis, as a result of a complex process that involves the activation of vascular and circulating cells, the release of soluble inflammatory and thrombotic mediators and blood clotting activation.

AREAS COVERED

This article reviews the pathophysiological role of platelets, neutrophils and the endothelium, and of their interactions, in the thrombotic complications of COVID-19 patients, and the current and future therapeutic approaches targeting these cell types.

EXPERT OPINION

Virus-induced platelet, neutrophil and endothelial cell changes are crucial triggers of the thrombotic complications and of the adverse evolution of COVID-19. Both the direct interaction with the virus and the associated cytokine storm concur to trigger cell activation in a classical thromboinflammatory vicious circle. Although heparin has proven to be an effective prophylactic and therapeutic weapon for the prevention and treatment of COVID-19-associated thrombosis, it acts downstream of the cascade of events triggered by SARS-CoV-2. The identification of specific molecular targets interrupting the thromboinflammatory cascade upstream, and more specifically acting either on the interaction of SARS-CoV-2 with blood and vascular cells or on the specific signalling mechanisms associated with their COVID-19-associated activation, might theoretically offer greater protection with potentially lesser side effects.

An anti-inflammatory and anti-fibrotic proprietary Chinese medicine nasal spray designated as Allergic Rhinitis Nose Drops (ARND) with potential to prevent SARS-CoV-2 coronavirus infection by targeting RBD (Delta)- angiotensin converting enzyme 2 (ACE2) binding

BACKGROUND

Since the outbreak of COVID-19 has resulted in over 313,000,000 confirmed cases of infection and over 5,500,000 deaths, substantial research work has been conducted to discover agents/ vaccines against COVID-19. Undesired adverse effects were observed in clinical practice and common vaccines do not protect the nasal tissue. An increasing volume of direct evidence based on clinical studies of traditional Chinese medicines (TCM) in the treatment of COVID-19 has been reported. However, the safe anti-inflammatory and anti-fibrotic proprietary Chinese medicines nasal spray, designated as Allergic Rhinitis Nose Drops (ARND), and its potential of re-purposing for suppressing viral infection via SARS-CoV-2 RBD (Delta)- angiotensin converting enzyme 2 (ACE2) binding have not been elucidated.

PURPOSE

To characterize ARND as a potential SARS-CoV-2 entry inhibitor for its possible preventive application in anti-virus hygienic agent.

METHODS

Network pharmacology analysis of ARND was adopted to asacertain gene targets which were commonly affected by COVID-19. The inhibitory effect of ARND on viral infection was determined by an in vitro pseudovirus assay. Furthermore, ARND was confirmed to have a strong binding affinity with ACE2 and SARS-CoV-2 spike-RBD (Delta) by ELISA. Finally, inflammatory and fibrotic cell models were used in conjunction in this study.

RESULTS

The results suggested ARND not only inhibited pseudovirus infection and undermined the binding affinity between ACE2 and the Spike protein (Delta), but also attenuated the inflammatory response upon infection and may lead to a better prognosis with a lower risk of pulmonary fibrosis. The data in this study also provide a basis for further development of ARND as an antiviral hygienic product and further investigations on ARND in the live virus, in vivo and COVID-19 patients. ARND holds promise for use in the current COVID-19 outbreak as well as in future pandemics.

CONCLUSION

ARND could be considered as a safe anti-SARS-CoV-2 agent with potential to prevent SARS-CoV-2 coronavirus infection.

Synthesis and Biological Evaluation of Novel Phthalide Analogs-1,2,4-Oxadiazole Hybrids as Potential Anti-Inflammatory Agents

A series of novel pathalide-1,2,4-oxadiazole analogs were synthesized for discovering novel anti-inflammatory agents. After the assessment of their cytotoxicity in vitro, all compounds had been screened for their anti-inflammatory activity by evaluating their inhibitory effect on LPS-induced NO production in RAW 264.7 macrophages. SARs had been concluded, and finally compound E13 was found to be the most potent compound. This compound could also significantly decrease the production of iNOS and COX-2. Preliminary mechanism studies indicated that compound E13 could inhibit the TLR4/NF-κB and ERK/p38 signaling pathways. These findings indicate that E13 holds great potential to be a lead compound for discovering novel anti-inflammatory drugs.

More questions than answers for the use of inhaled nitric oxide in COVID-19

Inhaled nitric oxide (iNO) is a potent vasodilator approved for use in term and near-term neonates, but with broad off-label use in settings including acute respiratory distress syndrome (ARDS). As an inhaled therapy, iNO reaches well ventilated portions of the lung and selectively vasodilates the pulmonary vascular bed, with little systemic effect due to its rapid inactivation in the bloodstream. iNO is well documented to improve oxygenation in a variety of pathological conditions, but in ARDS, these transient improvements in oxygenation have not translated into meaningful clinical outcomes. In coronavirus disease 2019 (COVID-19) related ARDS, iNO has been proposed as a potential treatment due to a variety of mechanisms, including its vasodilatory effect, antiviral properties, as well as anti-thrombotic and anti-inflammatory actions. Presently however, no randomized controlled data are available evaluating iNO in COVID-19, and published data are largely derived from retrospective and cohort studies. It is therefore important to interpret these limited findings with caution, as many questions remain around factors such as patient selection, optimal dosing, timing of administration, duration of administration, and delivery method. Each of these factors may influence whether iNO is indeed an efficacious therapy - or not - in this context. As such, until randomized controlled trial data are available, use of iNO in the treatment of patients with COVID-19 related ARDS should be considered on an individual basis with sound clinical judgement from the attending physician.

Impaired skin microvascular endothelial reactivity in critically ill COVID-19 patients

Background

Some clinical and histological studies have reported that SARS-CoV-2 infection may damage the endothelium. However, the impact of this virus on endothelial function in vivo remains poorly characterized. In this single-center pilot observational study, we performed iontophoresis of acetylcholine coupled with Laser doppler to investigate microvascular endothelial reactivity in COVID-19 patients compared to patients with non-COVID-19 bacterial pneumonia (NCBP) patients.

Results

During three consecutive months, 32 COVID-19 patients and 11 control NCBP patients with acute respiratory failure were included. The median age was 59 [50–68] and 69 [57–75] years in COVID-19 and NCBP groups, respectively (P = 0.11). There was no significant difference in comorbidities or medications between the two groups, except for body mass index, which was higher in COVID-19 patients. NCBP patients had a higher SAPS II score compared to COVID-19 patients (P < 0.0001), but SOFA score was not different between groups (P = 0.51). Global hemodynamic and peripheral tissue perfusion parameters were not different between groups. COVID-19 patients had significantly lower skin microvascular basal blood flow than NCBP patients (P = 0.02). In addition, endothelium-dependent microvascular reactivity was threefold lower in COVID-19 patients than NCBP patients (P = 0.008).

Conclusions

Both baseline skin microvascular blood flow and skin endothelial-dependent microvascular reactivity were impaired in critically ill COVID-19 patients compared to NCBP patients, despite a lower disease severity score supporting a specific pathogenic role of SARS-CoV-2 on the endothelium.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01027-3.

Disengaging the COVID-19 Clutch as a Discerning Eye Over the Inflammatory Circuit During SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the cytokine release syndrome (CRS) and leads to multiorgan dysfunction. Mitochondrial dynamics are fundamental to protect against environmental insults, but they are highly susceptible to viral infections. Defective mitochondria are potential sources of reactive oxygen species (ROS). Infection with SARS-CoV-2 damages mitochondria, alters autophagy, reduces nitric oxide (NO), and increases both nicotinamide adenine dinucleotide phosphate oxidases (NOX) and ROS. Patients with coronavirus disease 2019 (COVID-19) exhibited activated toll-like receptors (TLRs) and the Nucleotide-binding and oligomerization domain (NOD-), leucine-rich repeat (LRR-), pyrin domain-containing protein 3 (NLRP3) inflammasome. The activation of TLRs and NLRP3 by SARS‐CoV‐2 induces interleukin 6 (IL-6), IL-1β, IL-18, and lactate dehydrogenase (LDH). Herein, we outline the inflammatory circuit of COVID-19 and what occurs behind the scene, the interplay of NOX/ROS and their role in hypoxia and thrombosis, and the important role of ROS scavengers to reduce COVID-19-related inflammation.

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.

Compassionate use of Pulmonary Vasodilators in Acute Severe Hypoxic Respiratory Failure due to COVID-19

Background

There have been over 200 million cases and 4.4 million deaths from COVID-19 worldwide. Despite the lack of robust evidence one potential treatment for COVID-19 associated severe hypoxaemia is inhaled pulmonary vasodilator (IPVD) therapy, using either nitric oxide (iNO) or prostaglandins. We describe the implementation of, and outcomes from, a protocol using IPVDs in a cohort of patients with severe COVID-19 associated respiratory failure receiving maximal conventional support.

Methods

Prospectively collected data from adult patients with SARS-CoV-2 admitted to the intensive care unit (ICU) at a large teaching hospital were analysed for the period 14^th March 2020 - 11^th February 2021. An IPVD was considered if the PaO₂/FiO₂ (PF) ratio was less than 13.3kPa despite maximal conventional therapy. Nitric oxide was commenced at 20ppm and titrated to response. If oxygenation improved Iloprost nebulisers were commenced and iNO weaned. The primary outcome was percentage changes in PF ratio and Alveolar-arterial (A-a) gradient.

Results

Fifty-nine patients received IPVD therapy during the study period. The median PF ratio before IPVD therapy was commenced was 11.33kPa (9.93-12.91). Patients receiving an IPVD had a lower PF ratio (14.37 vs. 16.37kPa, p = 0.002) and higher APACHE-II score (17 vs. 13, p = 0.028) at ICU admission. At 72 hours after initiating an IPVD the median improvement in PF ratio was 33.9% (-4.3-84.1). At 72 hours changes in PF ratio (70.8 vs. −4.1%, p < 0.001) and reduction in A-a gradient (44.7 vs. 14.8%, p < 0.001) differed significantly between survivors (n = 33) and non-survivors (n = 26).

Conclusions

The response to IPVDs in patients with COVID-19 associated acute hypoxic respiratory failure differed significantly between survivors and non-survivors. Both iNO and prostaglandins may offer therapeutic options for patients with severe refractory hypoxaemia due to COVID-19. The use of inhaled prostaglandins, and iNO where feasible, should be studied in adequately powered prospective randomised trials.

The relationship between peripheral immune response and disease severity in SARS-CoV-2-infected subjects: A cross-sectional study

Coronavirus disease 2019 (COVID-19) is a respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and marked by an intense inflammatory response and immune dysregulation in the most severe cases. In order to better clarify the relationship between peripheral immune system changes and the severity of COVID-19, this study aimed to evaluate the frequencies and absolute numbers of peripheral subsets of neutrophils, monocytes, and dendritic cells (DCs), in addition to quantifying the levels of inflammatory mediators. One hundred fifty-seven COVID-19 patients were stratified into mild, moderate, severe, and critical disease categories. The cellular components and circulating cytokines were assessed by flow cytometry. Nitric oxide (NOx) and myeloperoxidase (MPO) levels were measured by colourimetric tests. COVID-19 patients presented neutrophilia, with signs of emergency myelopoiesis. Alterations in the monocytic component were observed in patients with moderate to critical illness, with an increase in classical monocytes and a reduction in nonclassical monocytes, in addition to a reduction in the expression of HLA-DR in all subtypes of monocytes, indicating immunosuppression. DCs, especially plasmacytoid DCs, also showed a large reduction in moderate to critical patients. COVID-19 patients showed an increase in MPO, interleukin (IL)-12, IL-6, IL-10, and IL-8, accompanied by a reduction in IL-17A and NOx. IL-10 levels ≥14 pg/ml were strongly related to the worst outcome, with a sensitivity of 78·3% and a specificity of 79·1%. The results of this study indicate the presence of systemic effects induced by COVID-19, which appear to be related to the pathophysiology of the disease, highlighting the potential of IL-10 as a possible prognostic biomarker for COVID-19.

Management of severe neonatal respiratory distress due to vertical transmission of severe acute respiratory syndrome coronavirus 2: a case report

Background

Neonates with severe acute respiratory syndrome coronavirus 2 infection are usually asymptomatic or have mild to moderate symptoms. Acute respiratory distress syndrome due to severe acute respiratory syndrome coronavirus 2 with respiratory insufficiency is rare. Therefore, information about the best intensive care strategy for neonates requiring mechanical ventilation is lacking. We report a neonatal case of severe acute respiratory distress syndrome, probably due to vertical transmission of severe acute respiratory syndrome coronavirus 2, complicated by Staphylococcus aureus sepsis. We aim to inform pediatric providers on the clinical course and acute management considerations in coronavirus disease-related neonatal acute respiratory distress syndrome.

Case presentation

A late preterm (gestational age 36 0/7 weeks) Caucasian girl was born from a severe acute respiratory syndrome coronavirus 2-positive mother and tested positive for severe acute respiratory syndrome coronavirus 2 at 19 hours after birth. She developed acute respiratory distress syndrome requiring intensive care admission and mechanical ventilation. The clinical course was complicated by S. aureus pneumonia and bacteremia. Multimodal management included well-established interventions for respiratory distress syndrome such as surfactant therapy, high-frequency oscillatory ventilation, and inhaled nitric oxide, combined with therapies extrapolated from adult care for severe acute respiratory syndrome coronavirus 2 patients such as dexamethasone, coronavirus disease 2019-specific immunoglobins, and prophylactic low-molecular-weight heparin. The neonate was successfully weaned from the ventilator and improved clinically.

Conclusion

This case shows a rare but serious neonatal severe acute respiratory syndrome coronavirus 2 infection, leading to severe acute respiratory distress syndrome. Because of limited therapy guidelines for neonates, we suggest multimodal management with awareness of the possibility of S. aureus coinfection, to treat this age group successful.

Virus-Induced Membrane Fusion in Neurodegenerative Disorders

A growing body of epidemiological and research data has associated neurotropic viruses with accelerated brain aging and increased risk of neurodegenerative disorders. Many viruses replicate optimally in senescent cells, as they offer a hospitable microenvironment with persistently elevated cytosolic calcium, abundant intracellular iron, and low interferon type I. As cell-cell fusion is a major driver of cellular senescence, many viruses have developed the ability to promote this phenotype by forming syncytia. Cell-cell fusion is associated with immunosuppression mediated by phosphatidylserine externalization that enable viruses to evade host defenses. In hosts, virus-induced immune dysfunction and premature cellular senescence may predispose to neurodegenerative disorders. This concept is supported by novel studies that found postinfectious cognitive dysfunction in several viral illnesses, including human immunodeficiency virus-1, herpes simplex virus-1, and SARS-CoV-2. Virus-induced pathological syncytia may provide a unified framework for conceptualizing neuronal cell cycle reentry, aneuploidy, somatic mosaicism, viral spreading of pathological Tau and elimination of viable synapses and neurons by neurotoxic astrocytes and microglia. In this narrative review, we take a closer look at cell-cell fusion and vesicular merger in the pathogenesis of neurodegenerative disorders. We present a "decentralized" information processing model that conceptualizes neurodegeneration as a systemic illness, triggered by cytoskeletal pathology. We also discuss strategies for reversing cell-cell fusion, including, TMEM16F inhibitors, calcium channel blockers, senolytics, and tubulin stabilizing agents. Finally, going beyond neurodegeneration, we examine the potential benefit of harnessing fusion as a therapeutic strategy in regenerative medicine.

Targeting Arginine in COVID-19-Induced Immunopathology and Vasculopathy

Coronavirus disease 2019 (COVID-19) represents a major public health crisis that has caused the death of nearly six million people worldwide. Emerging data have identified a deficiency of circulating arginine in patients with COVID-19. Arginine is a semi-essential amino acid that serves as key regulator of immune and vascular cell function. Arginine is metabolized by nitric oxide (NO) synthase to NO which plays a pivotal role in host defense and vascular health, whereas the catabolism of arginine by arginase to ornithine contributes to immune suppression and vascular disease. Notably, arginase activity is upregulated in COVID-19 patients in a disease-dependent fashion, favoring the production of ornithine and its metabolites from arginine over the synthesis of NO. This rewiring of arginine metabolism in COVID-19 promotes immune and endothelial cell dysfunction, vascular smooth muscle cell proliferation and migration, inflammation, vasoconstriction, thrombosis, and arterial thickening, fibrosis, and stiffening, which can lead to vascular occlusion, muti-organ failure, and death. Strategies that restore the plasma concentration of arginine, inhibit arginase activity, and/or enhance the bioavailability and potency of NO represent promising therapeutic approaches that may preserve immune function and prevent the development of severe vascular disease in patients with COVID-19.

Implication of COVID-19 on Erythrocytes Functionality: Red Blood Cell Biochemical Implications and Morpho-Functional Aspects

Several diseases (such as diabetes, cancer, and neurodegenerative disorders) affect the morpho-functional aspects of red blood cells, sometimes altering their normal metabolism. In this review, the hematological changes are evaluated, with particular focus on the morphology and metabolic aspects of erythrocytes. Changes in the functionality of such cells may, in fact, help provide important information about disease severity and progression. The viral infection causes significant damage to the blood cells that are altered in size, rigidity, and distribution width. Lower levels of hemoglobin and anemia have been reported in several studies, and an alteration in the concentration of antioxidant enzymes has been shown to promote a dangerous state of oxidative stress in red blood cells. Patients with severe COVID-19 showed an increase in hematological changes, indicating a progressive worsening as COVID-19 severity progressed. Therefore, monitored hematological alterations in patients with COVID-19 may play an important role in the management of the disease and prevent the risk of a severe course of the disease. Finally, monitored changes in erythrocytes and blood, in general, may be one of the causes of the condition known as Long COVID.

Application of multivariate statistical analysis and network pharmacology to explore the mechanism of Danggui Liuhuang Tang in treating perimenopausal syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Danggui Liuhuang Tang (DGLHT), first recorded in "Lan-Shi-Mi-Cang" (written in 1276 AD), is a famous classical formula. In 2018, it was listed in the Catalogue of Ancient Classic and Famous Prescriptions (First Batch) formulated by the National Administration of Traditional Chinese Medicine and the National Medical Products Administration. Perimenopausal syndrome (PMS) refers to a series of syndromes with autonomic nervous system dysfunction and neuropsychological symptoms. The treatment of PMS demands non-hormonal drugs. Natural products are considered to be effective substitutes for the treatment of PMS. It is reported that DGLHT has not only good therapeutic effects but also higher safety and fewer side effects in the treatment of PMS. However, the mechanism of DGLHT in treating PMS is not clear.

AIM OF THE STUDY

To explore the chemical basis and the mechanism of DGLHT in treating PMS.

MATERIALS AND METHODS

Multivariate statistical analysis was used to analyze the difference of components in supernatant before and after compatibility of DGLHT based on LC-MS data. The qualitative analysis was performed on the precipitate formed in the decocting process using LC-MS while the quantitative analysis on the potential markers using LC-UV. Then, the potential markers were analyzed by network pharmacology. The regulatory effect of DGLHT on FSH, P and E₂ were carried out in PMS rats.

RESULTS

Five potential markers, epiberberine, coptisine, palmatine, berberine and baicalin, were screened from the analysis of compounds in the supernatant. Four complexes, composed of potential marker monomers, were identified in the sediment, including two that have not been reported. The key targets of potential markers include TNF, NOS3, EGFR, ESR1, PTGS2, AR, CDC42 and RPS6KB1. The top signaling pathways include the cGMP-PKG signaling pathway, PI3K-Akt signaling pathway and estrogen signaling pathway. DGLHT could call back the hormone levels of P and E₂ in PMS rats.

CONCLUSION

DGLHT active ingredients, epiberberine, coptisine, palmatine, berberine and baicalin contribute a lot to the therapeutic effect. And DGLHT takes effect by regulating hormones secreted by the ovary.

Therapeutic Effects of Inhaled Nitric Oxide Therapy in COVID-19 Patients

The global COVID-19 pandemic has become the largest public health challenge of recent years. The incidence of COVID-19-related acute hypoxemic respiratory failure (AHRF) occurs in up to 15% of hospitalized patients. Antiviral drugs currently available to clinicians have little to no effect on mortality, length of in-hospital stay, the need for mechanical ventilation, or long-term effects. Inhaled nitric oxide (iNO) administration is a promising new non-standard approach to directly treat viral burden while enhancing oxygenation. Along with its putative antiviral affect in COVID-19 patients, iNO can reduce inflammatory cell-mediated lung injury by inhibiting neutrophil activation, lowering pulmonary vascular resistance and decreasing edema in the alveolar spaces, collectively enhancing ventilation/perfusion matching. This narrative review article presents recent literature on the iNO therapy use for COVID-19 patients. The authors suggest that early administration of the iNO therapy may be a safe and promising approach for the treatment of COVID-19 patients. The authors also discuss unconventional approaches to treatment, continuous versus intermittent high-dose iNO therapy, timing of initiation of therapy (early versus late), and novel delivery systems. Future laboratory and clinical research is required to define the role of iNO as an adjunct therapy against bacterial, viral, and fungal infections.

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.

Vascular Damage, Thromboinflammation, Plasmablast Activation, T-Cell Dysregulation and Pathological Histiocytic Response in Pulmonary Draining Lymph Nodes of COVID-19

Although initial immunophenotypical studies on peripheral blood and bronchoalveolar lavage samples have provided a glimpse into the immunopathology of COVID-19, analyses of pulmonary draining lymph nodes are currently scarce. 22 lethal COVID-19 cases and 28 controls were enrolled in this study. Pulmonary draining lymph nodes (mediastinal, tracheal, peribronchial) were collected at autopsy. Control lymph nodes were selected from a range of histomorphological sequelae [unremarkable histology, infectious mononucleosis, follicular hyperplasia, non-SARS related HLH, extrafollicular plasmablast activation, non-SARS related diffuse alveolar damage (DAD), pneumonia]. Samples were mounted on a tissue microarray and underwent immunohistochemical staining for a selection of immunological markers and in-situ hybridization for Epstein Barr Virus (EBV) and SARS-CoV-2. Gene expression profiling was performed using the HTG EdgeSeq Immune Response Panel. Characteristic patterns of a dysregulated immune response were detected in COVID-19: 1. An accumulation of extrafollicular plasmablasts with a relative paucity or depletion of germinal centers. 2. Evidence of T-cell dysregulation demonstrated by immunohistochemical paucity of FOXP3+, Tbet+ and LEF1+ positive T-cells and a downregulation of key genes responsible for T-cell crosstalk, maturation and migration as well as a reactivation of herpes viruses in 6 COVID-19 lymph nodes (EBV, HSV). 3. Macrophage activation by a M2-polarized, CD163+ phenotype and increased incidence of hemophagocytic activity. 4. Microvascular dysfunction, evidenced by an upregulation of hemostatic (CD36, PROCR, VWF) and proangiogenic (FLT1, TEK) genes and an increase of fibrin microthrombi and CD105+ microvessels. Taken together, these findings imply widespread dysregulation of both innate and adoptive pathways with concordant microvascular dysfunction in severe COVID-19.

Mitochondrial Dynamics in SARS-COV2 Spike Protein Treated Human Microglia: Implications for Neuro-COVID

Emerging clinical data from the current COVID-19 pandemic suggests that ~ 40% of COVID-19 patients develop neurological symptoms attributed to viral encephalitis while in COVID long haulers chronic neuro-inflammation and neuronal damage result in a syndrome described as Neuro-COVID. We hypothesize that SAR-COV2 induces mitochondrial dysfunction and activation of the mitochondrial-dependent intrinsic apoptotic pathway, resulting in microglial and neuronal apoptosis. The goal of our study was to determine the effect of SARS-COV2 on mitochondrial biogenesis and to monitor cell apoptosis in human microglia non-invasively in real time using Raman spectroscopy, providing a unique spatio-temporal information on mitochondrial function in live cells. We treated human microglia with SARS-COV2 spike protein and examined the levels of cytokines and reactive oxygen species (ROS) production, determined the effect of SARS-COV2 on mitochondrial biogenesis and examined the changes in molecular composition of phospholipids. Our results show that SARS- COV2 spike protein increases the levels of pro-inflammatory cytokines and ROS production, increases apoptosis and increases the oxygen consumption rate (OCR) in microglial cells. Increases in OCR are indicative of increased ROS production and oxidative stress suggesting that SARS-COV2 induced cell death. Raman spectroscopy yielded significant differences in phospholipids such as Phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC), which account for ~ 80% of mitochondrial membrane lipids between SARS-COV2 treated and untreated microglial cells. These data provide important mechanistic insights into SARS-COV2 induced mitochondrial dysfunction which underlies neuropathology associated with Neuro-COVID.

COVID-19: A Redox Disease-What a Stress Pandemic Can Teach Us About Resilience and What We May Learn from the Reactive Species Interactome About Its Treatment

Significance: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19), affects every aspect of human life by challenging bodily, socioeconomic, and political systems at unprecedented levels. As vaccines become available, their distribution, safety, and efficacy against emerging variants remain uncertain, and specific treatments are lacking. Recent Advances: Initially affecting the lungs, COVID-19 is a complex multisystems disease that disturbs the whole-body redox balance and can be long-lasting (Long-COVID). Numerous risk factors have been identified, but the reasons for variations in susceptibility to infection, disease severity, and outcome are poorly understood. The reactive species interactome (RSI) was recently introduced as a framework to conceptualize how cells and whole organisms sense, integrate, and accommodate stress. Critical Issues: We here consider COVID-19 as a redox disease, offering a holistic perspective of its effects on the human body, considering the vulnerability of complex interconnected systems with multiorgan/multilevel interdependencies. Host/viral glycan interactions underpin SARS-CoV-2's extraordinary efficiency in gaining cellular access, crossing the epithelial/endothelial barrier to spread along the vascular/lymphatic endothelium, and evading antiviral/antioxidant defences. An inflammation-driven "oxidative storm" alters the redox landscape, eliciting epithelial, endothelial, mitochondrial, metabolic, and immune dysfunction, and coagulopathy. Concomitantly reduced nitric oxide availability renders the sulfur-based redox circuitry vulnerable to oxidation, with eventual catastrophic failure in redox communication/regulation. Host nutrient limitations are crucial determinants of resilience at the individual and population level. Future Directions: While inflicting considerable damage to health and well-being, COVID-19 may provide the ultimate testing ground to improve the diagnosis and treatment of redox-related stress diseases. "Redox phenotyping" of patients to characterize whole-body RSI status as the disease progresses may inform new therapeutic approaches to regain redox balance, reduce mortality in COVID-19 and other redox diseases, and provide opportunities to tackle Long-COVID. Antioxid. Redox Signal. 35, 1226-1268.

BPC 157 as Potential Treatment for COVID-19

The emergence of coronavirus disease (COVID-19) in China at the end of 2019 has caused a large global outbreak. COVID-19 is largely seen as a thrombotic and vascular disease targeting endothelial cells (ECs) throughout the body that can provoke the breakdown of central vascular functions. This explains the complications and multi-organ failure seen in COVID-19 patients including acute respiratory distress syndrome, cardiovascular complications, liver damage, and neurological damage. Acknowledging the comorbidities and potential organ injuries throughout the course of COVID-19 is therefore crucial in the clinical management of patients. Here we discuss BPC 157, based primarily on animal model data, as a novel agent that can improve the clinical management of COVID-19. BPC 157 is a peptide that has demonstrated anti-inflammatory, cytoprotective, and endothelial-protective effects in different organ systems in different species. BPC 157 activated endothelial nitric oxide synthase (eNOS) is associated with nitric oxide (NO) release, tissue repair and angiomodulatory properties which can lead to improved vascular integrity and immune response, reduced proinflammatory profile, and reduced critical levels of the disease. As a result, discussion of its use as a potential prophylactic and complementary treatment is critical. All examined treatments, although potentiality effective against COVID-19, need either appropriate drug development or clinical trials in humans to be suitable for clinical use.

Serum nitrite and nitrate: A potential biomarker for post-covid-19 complications?

Nitric oxide (NO) plays an important role in cardiovascular and immune systems. Quantification of blood nitrite and nitrate, two relatively stable metabolites of NO (generally as NO_x), has been acknowledged, in part, representing NO bioactivity. Dysregulation of NO_x had been reported in SARS-CoV-2 infected populations, but whether patients recovered from COVID-19 disease present with restored NO_x is unknown. In this study, serum NO₂^- and NO₃^- were quantified and analyzed among 109 recovered adults in comparison to a control group of 166 uninfected adults. Nitrite or nitrate levels were not significantly different among mild-, common-, severe- and critical-type patients. However, these recovered patients had dramatically lower NO₂^- and NO₂^-/NO₃^- than the uninfected group (p < 0.0001), with significantly higher NO₃^- levels (p = 0.0023) than the uninfected group. Nitrate and nitrite/nitrate were positively and negatively correlated with patient age, respectively, with age 65 being a turning point among recovered patients. These results indicate that low NO₂^-, low NO₂^-/NO₃^- and high NO₃^- may be potential biomarkers of long-term poor or irreversible outcomes after SARS-CoV-2 infection. It suggests that NO metabolites might serve as a predictor to track the health status of recovered COVID-19 patients, highlighting the need to elucidate the role of NO after SARS-CoV-2 infection.

Nrf2 activator PB125® as a carnosic acid-based therapeutic agent against respiratory viral diseases, including COVID-19

PB125® is a phytochemical composition providing potent Nrf2 activation as well as a number of direct actions that do not involve Nrf2. Nrf2 is a transcription actor that helps maintain metabolic balance by providing redox-sensitive expression of numerous genes controlling normal day-to-day metabolic pathways. When ordinary metabolism is upset by extraordinary events such as injury, pathogenic infection, air or water pollution, ingestion of toxins, or simply by the slow but incessant changes brought about by aging and genetic variations, Nrf2 may also be called into action by the redox changes resulting from these events, whether acute or chronic. A complicating factor in all of this is that Nrf2 levels decline with aging, leaving the elderly less able to maintain proper redox balance. The dysregulated gene expression that results can cause or exacerbate a wide variety of pathological conditions, including susceptibility to viral infections. This review examines the characteristics desirable in Nrf2 activators that have therapeutic potential, as well as some of the patterns of dysregulated gene expression commonly observed during pulmonary infections and the normalizing effects possible by judicious use of phytochemicals to increase the activation level of available Nrf2.

Lead-Free Halide Cs2PtI6 Perovskite Favoring Pt-N Bonding for Trace NO Detection

In recent years, the performance research of perovskite materials is not only concentrated in the field of solar cells or optics, but the field of gas sensing has gradually entered the public view. However, the detection of nitric oxide (NO) by lead-free halide perovskites has not yet been reported. Herein, we use Cs₂PtI₆ to realize the first example of a halide perovskite applied to NO sensing. Due to favoring Pt-N binding, the material has some excellent properties such as a NO detection limit as low as 100 parts-per-billion (ppb), ultrahigh selectivity to NO, and can work at room temperature for more than 2 months. In situ sum frequency generation (SFG) spectra and crystal orbital Hamilton population (COHP) analysis reveal that the strong bonding interaction between Pt 5s and N 2s ensure the high adsorption energy, and Pt 5d electron back donation to N 2p_x, N 2p_z antibonding causes the conductive change of the sensors. In addition, its flexible wearable technology shows the application potential of the device and promotes the further development of perovskite materials.

A novel pre-clinical strategy to deliver antimicrobial doses of inhaled nitric oxide

Effective treatment of respiratory infections continues to be a major challenge. In high doses (≥160 ppm), inhaled Nitric Oxide (iNO) has been shown to act as a broad-spectrum antimicrobial agent, including its efficacy in vitro for coronavirus family. However, the safety of prolonged in vivo implementation of high-dose iNO therapy has not been studied. Herein we aim to explore the feasibility and safety of delivering continuous high-dose iNO over an extended period of time using an in vivo animal model. Yorkshire pigs were randomized to one of the following two groups: group 1, standard ventilation; and group 2, standard ventilation + continuous iNO 160 ppm + methylene blue (MB) as intravenous bolus, whenever required, to maintain metHb <6%. Both groups were ventilated continuously for 6 hours, then the animals were weaned from sedation, mechanical ventilation and followed for 3 days. During treatment, and on the third post-operative day, physiologic assessments were performed to monitor lung function and other significative markers were assessed for potential pulmonary or systemic injury. No significant change in lung function, or inflammatory markers were observed during the study period. Both gas exchange function, lung tissue cytokine analysis and histology were similar between treated and control animals. During treatment, levels of metHb were maintained <6% by administration of MB, and NO2 remained <5 ppm. Additionally, considering extrapulmonary effects, no significant changes were observed in biochemistry markers. Our findings showed that high-dose iNO delivered continuously over 6 hours with adjuvant MB is clinically feasible and safe. These findings support the development of investigations of continuous high-dose iNO treatment of respiratory tract infections, including SARS-CoV-2.

Impairment of hypoxic pulmonary vasoconstriction in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a serious complication of severe systemic or local pulmonary inflammation, such as caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. ARDS is characterised by diffuse alveolar damage that leads to protein-rich pulmonary oedema, local alveolar hypoventilation and atelectasis. Inadequate perfusion of these areas is the main cause of hypoxaemia in ARDS. High perfusion in relation to ventilation (V/Q<1) and shunting (V/Q=0) is not only caused by impaired hypoxic pulmonary vasoconstriction but also redistribution of perfusion from obstructed lung vessels. Rebalancing the pulmonary vascular tone is a therapeutic challenge. Previous clinical trials on inhaled vasodilators (nitric oxide and prostacyclin) to enhance perfusion to high V/Q areas showed beneficial effects on hypoxaemia but not on mortality. However, specific patient populations with pulmonary hypertension may profit from treatment with inhaled vasodilators. Novel treatment targets to decrease perfusion in low V/Q areas include epoxyeicosatrienoic acids and specific leukotriene receptors. Still, lung protective ventilation and prone positioning are the best available standard of care. This review focuses on disturbed perfusion in ARDS and aims to provide basic scientists and clinicians with an overview of the vascular alterations and mechanisms of V/Q mismatch, current therapeutic strategies, and experimental approaches.

Inhaled Nitric Oxide via High-Flow Nasal Cannula in Patients with Acute Respiratory Failure Related to COVID-19

INTRODUCTION

Limited evidence exists regarding use of inhaled nitric oxide (iNO) in spontaneously breathing patients. We evaluated the effectiveness of continuous iNO via high-flow nasal cannula (HFNC) in COVID-19 respiratory failure.

METHODS

We performed a multicenter cohort study of patients with respiratory failure from COVID-19 managed with HFNC. Patients were stratified by administration of iNO via HFNC. Regression analysis was used to compare the need for mechanical ventilation and secondary endpoints including hospital mortality, length of stay, acute kidney injury, need for renal replacement therapy, and need for extracorporeal life support.

RESULTS

A total of 272 patients were identified and 66 (24.3%) of these patients received iNO via HFNC for a median of 88 h (interquartile range: 44, 135). After 12 h of iNO, supplemental oxygen requirement was unchanged or increased in 52.7% of patients. Twenty-nine (43.9%) patients treated with iNO compared to 79 (38.3%) patients without iNO therapy required endotracheal intubation (P = .47). After multivariable adjustment, there was no difference in need for mechanical ventilation between groups (odds ratio: 1.53; 95% confidence interval [CI]: 0.74-3.17), however, iNO administration was associated with longer hospital length of stay (incidence rate ratio: 1.41; 95% CI: 1.31-1.51). No difference was found for mortality, acute kidney injury, need for renal replacement therapy, or need for extracorporeal life support.

CONCLUSION

In patients with COVID-19 respiratory failure, iNO delivered via HFNC did not reduce oxygen requirements in the majority of patients or improve clinical outcomes. Given the observed association with increased length of stay, judicious selection of those likely to benefit from this therapy is warranted.

Age-Associated Increase in Thrombogenicity and Its Correlation with von Willebrand Factor

Endothelial cells that cover the lumen of all blood vessels have the inherent capacity to express both pro and anticoagulant molecules. However, under normal physiological condition, they generally function to maintain a non-thrombogenic surface for unobstructed blood flow. In response to injury, certain stimuli, or as a result of dysfunction, endothelial cells release a highly adhesive procoagulant protein, von Willebrand factor (VWF), which plays a central role in formation of platelet aggregates and thrombus generation. Since VWF expression is highly restricted to endothelial cells, regulation of its levels is among the most important functions of endothelial cells for maintaining hemostasis. However, with aging, there is a significant increase in VWF levels, which is concomitant with a significant rise in thrombotic events. It is not yet clear why and how aging results in increased VWF levels. In this review, we have aimed to discuss the age-related increase in VWF, its potential mechanisms, and associated coagulopathies as probable consequences.

Laboratory and Imaging Evaluation of Cardiac Involvement in Patients with Post-Acute COVID-19

Background

In the post-acute COVID-19 syndrome, many patients suffer from palpitations, effort-associated fatigue, and even sudden death. The mechanism of heart involvement in this syndrome is uncertain. The main purpose of the study was to identify possible cardiac involvement causes in patients with post-acute COVID-19 by using biomarkers such as NT-proBNP and nitric oxide (NO) and cardiac imaging modalities.

Methods

In this cross-sectional study, a total of 105 participants were included according to the existence of symptoms, and 40 of these participants were asymptomatic patients. The ages of the participants ranged from 20 to 50 years. All patients were healthy before COVID-19. The symptoms were defined as palpitations and/or fatigue association with exercise in post-acute COVID-19 term. The comparison of the two groups was made by using biochemical parameters (NT-proBNP, Troponin I, NO) and imaging techniques (echocardiography, cardiovascular magnetic resonance (CMR) and cardiac positron emission tomography (PET)).

Results

The symptomatic patients had higher NT-proBNP levels compared with asymptomatic patients (132.30±35.15; 76.86±16.79, respectively; p < 0.001). Interestingly, the symptomatic patients had lower NO levels than asymptomatic patients (9.20±3.08; 16.15±6.02, respectively; p < 0.001). Echocardiography and CMR were normal. However, we found regional increased 18F-FDG uptake on cardiac PET to be compatible with myocardial fatigue.

Conclusion

We found elevated NT-proNBP levels, low serum NO levels, and increased 18F-FDG uptake on cardiac PET in post-acute COVID syndrome. Cardiac PET could replace or be added to CMR for detecting subtle subacute/chronic myocarditis. The follow-up of patients with post-acute COVID-19 could target the possibility of risk of heart failure.