SARS-CoV-2 Entry Receptor ACE2 Is Expressed on Very Small CD45- Precursors of Hematopoietic and Endothelial Cells and in Response to Virus Spike Protein Activates the Nlrp3 Inflammasome

Extracellular Adenosine Triphosphate (eATP) and Its Metabolite, Extracellular Adenosine (eAdo), as Opposing "Yin-Yang" Regulators of Nlrp3 Inflammasome in the Trafficking of Hematopoietic Stem/Progenitor Cells

Nlrp3 inflammasome plays a pleiotropic role in hematopoietic cells. On the one hand, physiological activation of this intracellular protein complex is crucial to maintaining normal hematopoiesis and the trafficking of hematopoietic stem progenitor cells (HSPCs). On the other hand, its hyperactivation may lead to cell death by pyroptosis, and prolonged activity is associated with sterile inflammation of the BM and, as a consequence, with the HSPCs aging and origination of myelodysplasia and leukemia. Thus, we need to understand better this protein complex’s actions to define the boundaries of its safety window and study the transition from being beneficial to being detrimental. As demonstrated, the Nlrp3 inflammasome is expressed and active both in HSPCs and in the non-hematopoietic cells that are constituents of the bone marrow (BM) microenvironment. Importantly, the Nlrp3 inflammasome responds to mediators of purinergic signaling, and while extracellular adenosine triphosphate (eATP) activates this protein complex, its metabolite extracellular adenosine (eAdo) has the opposite effect. In this review, we will discuss and focus on the physiological consequences of the balance between eATP and eAdo in regulating the trafficking of HSPCs in an Nlrp3 inflammasome-dependent manner, as seen during pharmacological mobilization from BM into peripheral blood (PB) and in the reverse mechanism of homing from PB to BM and engraftment. We propose that both mediators of purinergic signaling and the Nlrp3 inflammasome itself may become important therapeutic targets in optimizing the trafficking of HSPCs in clinical settings.

SARS-CoV-2 and endothelial cell interaction in COVID-19: molecular perspectives

SARS-CoV-2 is the agent responsible for the coronavirus disease (COVID-19), which has been declared a pandemic by the World Health Organization. The clinical evolution of COVID-19 ranges from asymptomatic infection to death. Older people and patients with underlying medical conditions, particularly diabetes, cardiovascular and chronic respiratory diseases are more susceptible to develop severe forms of COVID-19. Significant endothelial damage has been reported in COVID-19 and growing evidence supports the key pathophysiological role of this alteration in the onset and the progression of the disease. In particular, the impaired vascular homeostasis secondary to the structural and functional damage of the endothelium and its main component, the endothelial cells, contributes to the systemic proinflammatory state and the multiorgan involvement observed in COVID-19 patients. This review summarizes the current evidence supporting the proposition that the endothelium is a key target of SARS-CoV-2, with a focus on the molecular mechanisms involved in the interaction between SARS-CoV-2 and endothelial cells.

Human Hematopoietic Stem, Progenitor, and Immune Cells Respond Ex Vivo to SARS-CoV-2 Spike Protein

Despite evidence that SARS-CoV-2 infection is systemic in nature, there is little known about the effects that SARS-CoV-2 infection or exposure has on many host cell types, including primitive and mature hematopoietic cells. The hematopoietic system is responsible for giving rise to the very immune cells that defend against viral infection and is a source of hematopoietic stem cells (HSCs) and progenitor cells (HPCs) which are used for hematopoietic cell transplantation (HCT) to treat hematologic disorders, thus there is a strong need to understand how exposure to the virus may affect hematopoietic cell functions. We examined the expression of ACE2, to which SARS-CoV-2 Spike (S) protein binds to facilitate viral entry, in cord blood derived HSCs/HPCs and in peripheral blood derived immune cell subtypes. ACE2 is expressed in low numbers of immune cells, higher numbers of HPCs, and up to 65% of rigorously defined HSCs. We also examined effects of exposing HSCs/HPCs and immune cells to SARS-CoV-2 S protein ex vivo. HSCs and HPCs expand less effectively and have less functional colony forming capacity when grown with S protein, while peripheral blood monocytes upregulate CD14 expression and show distinct changes in size and granularity. That these effects are induced by recombinant S protein alone and not the infectious viral particle suggests that simple exposure to SARS-CoV-2 may impact HSCs/HPCs and immune cells via S protein interactions with the cells, regardless of whether they can be infected. These data have implications for immune response to SARS-CoV-2 and for HCT. Graphical Abstract • Human HSCs, HPCs, and immune cells express ACE2 on the cell surface, making them potentially susceptible to SARS-CoV-2 infection. • SARS-CoV-2 S protein, which binds to ACE2, induces defects in the colony forming capacity of human HPC and inhibits the expansion of HSC/HPC subpopulations ex vivo. These effects can be at least partially neutralized by treatment with SARS-CoV-2 targeting antibody, recombinant human ACE2, or Angiotensin1-7. • S protein also induces aberrant morphological changes in peripheral blood derived monocytes ex vivo. • Thus, there are many different manners in which SARS-CoV-2 virus may impact the functional hematopoietic system, which has important implications for hematological manifestations of COVID-19 (i.e. thrombocytopenia and lymphopenia), immune response, and hematopoietic stem cell transplant in the era of COVID-19.

Predicting the Severity of Disease Progression in COVID-19 at the Individual and Population Level: A Mathematical Model

The impact of COVID-19 disease on health and economy has been global, and the magnitude of devastation is unparalleled in modern history. Any potential course of action to manage this complex disease requires the systematic and efficient analysis of data that can delineate the underlying pathogenesis. We have developed a mathematical model of disease progression to predict the clinical outcome, utilizing a set of causal factors known to contribute to COVID-19 pathology such as age, comorbidities, and certain viral and immunological parameters. Viral load and selected indicators of a dysfunctional immune response, such as cytokines IL-6 and IFNα which contribute to the cytokine storm and fever, parameters of inflammation D-Dimer and Ferritin, aberrations in lymphocyte number, lymphopenia, and neutralizing antibodies were included for the analysis. The model provides a framework to unravel the multi-factorial complexities of the immune response manifested in SARS-CoV-2 infected individuals. Further, this model can be valuable to predict clinical outcome at an individual level, and to develop strategies for allocating appropriate resources to manage severe cases at a population level.

Safety and efficacy of autologous non-hematopoietic enriched stem cell nebulization in COVID-19 patients: a randomized clinical trial, Abu Dhabi 2020

BACKGROUND

The novel SARS-CoV-2 has caused the coronavirus disease 2019 (COVID-19) pandemic. Currently, with insufficient worldwide vaccination rates, identifying treatment solutions to reduce the impact of the virus is urgently needed.

METHOD

An adaptive, multicentric, open-label, and randomized controlled phase I/II clinical trial entitled the "SENTAD-COVID Study" was conducted by the Abu Dhabi Stem Cells Center under exceptional conditional approval by the Emirates Institutional Review Board (IRB) for COVID-19 Research Committee from April 4th to July 31st, 2020, using an autologous peripheral blood non-hematopoietic enriched stem cell cocktail (PB-NHESC-C) administered by compressor (jet) nebulization as a complement to standard care therapy. The primary endpoints include safety and efficacy assessments, adverse events, the mortality rate within 28 days, and the time to clinical improvement as measured by a 2-point reduction on a seven-category ordinal scale or discharge from the hospital whichever occurred first.

RESULTS

The study included a total of 139 randomized COVID-19 patients, with 69 in the experimental group and 70 in the control group (standard care). Overall survival was 94.20% for the cocktail-treated group vs. 90.27% for the control group. Adverse events were reported in 50 (72.46%) patients receiving PB-NHESC-C and 51 (72.85%) in the control group (p = 0.9590), with signs and symptoms commonly found in COVID-19. After the first 9 days of the intervention, 67.3% of cocktail-treated patients recovered and were released from hospitals compared to 53.1% (RR = 0.84; 95% CI, 0.56-1.28) in the control group. Improvement, i.e., at least a 2-point reduction in the severity scale, was more frequently observed in cocktail-treated patients (42.0%) than in controls (17.0%) (RR = 0.69; 95% CI, 0.56-0.88).

CONCLUSIONS

Cocktail treatment improved clinical outcomes without increasing adverse events. Thus, the nebulization of PB-NHESC-C was safe and effective for treatment in most of these patients.

TRIAL REGISTRATION

ClinicalTrials.gov. NCT04473170. It was retrospectively registered on July 16th, 2020.

Nutraceutical Strategies for Suppressing NLRP3 Inflammasome Activation: Pertinence to the Management of COVID-19 and Beyond

Inflammasomes are intracellular protein complexes that form in response to a variety of stress signals and that serve to catalyze the proteolytic conversion of pro-interleukin-1β and pro-interleukin-18 to active interleukin-1β and interleukin-18, central mediators of the inflammatory response; inflammasomes can also promote a type of cell death known as pyroptosis. The NLRP3 inflammasome has received the most study and plays an important pathogenic role in a vast range of pathologies associated with inflammation-including atherosclerosis, myocardial infarction, the complications of diabetes, neurological and autoimmune disorders, dry macular degeneration, gout, and the cytokine storm phase of COVID-19. A consideration of the molecular biology underlying inflammasome priming and activation enables the prediction that a range of nutraceuticals may have clinical potential for suppressing inflammasome activity-antioxidants including phycocyanobilin, phase 2 inducers, melatonin, and N-acetylcysteine, the AMPK activator berberine, glucosamine, zinc, and various nutraceuticals that support generation of hydrogen sulfide. Complex nutraceuticals or functional foods featuring a number of these agents may find utility in the prevention and control of a wide range of medical disorders.

ACE2 in the renin-angiotensin system

In 2020 we are celebrating the 20th anniversary of the angiotensin-converting enzyme 2 (ACE2) discovery. This event was a landmark that shaped the way that we see the renin-angiotensin system (RAS) today. ACE2 is an important molecular hub that connects the RAS classical arm, formed mainly by the octapeptide angiotensin II (Ang II) and its receptor AT1, with the RAS alternative or protective arm, formed mainly by the heptapeptides Ang-(1-7) and alamandine, and their receptors, Mas and MrgD, respectively. In this work we reviewed classical and modern literature to describe how ACE2 is a critical component of the protective arm, particularly in the context of the cardiac function, coagulation homeostasis and immune system. We also review recent literature to present a critical view of the role of ACE2 and RAS in the SARS-CoV-2 pandemic.

Pandemic Perspective: Commonalities Between COVID-19 and Cardio-Oncology

Overlapping commonalities between coronavirus disease of 2019 (COVID-19) and cardio-oncology regarding cardiovascular toxicities (CVT), pathophysiology, and pharmacology are special topics emerging during the pandemic. In this perspective, we consider an array of CVT common to both COVID-19 and cardio-oncology, including cardiomyopathy, ischemia, conduction abnormalities, myopericarditis, and right ventricular (RV) failure. We also emphasize the higher risk of severe COVID-19 illness in patients with cardiovascular disease (CVD) or its risk factors or cancer. We explore commonalities in the underlying pathophysiology observed in COVID-19 and cardio-oncology, including inflammation, cytokine release, the renin-angiotensin-aldosterone-system, coagulopathy, microthrombosis, and endothelial dysfunction. In addition, we examine common pharmacologic management strategies that have been elucidated for CVT from COVID-19 and various cancer therapies. The use of corticosteroids, as well as antibodies and inhibitors of various molecules mediating inflammation and cytokine release syndrome, are discussed. The impact of angiotensin converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) is also addressed, since these drugs are used in cardio-oncology and have received considerable attention during the COVID-19 pandemic, since the culprit virus enters human cells via the angiotensin converting enzyme 2 (ACE2) receptor. There are therefore several areas of overlap, similarity, and interaction in the toxicity, pathophysiology, and pharmacology profiles in COVID-19 and cardio-oncology syndromes. Learning more about either will likely provide some level of insight into both. We discuss each of these topics in this viewpoint, as well as what we foresee as evolving future directions to consider in cardio-oncology during the pandemic and beyond. Finally, we highlight commonalities in health disparities in COVID-19 and cardio-oncology and encourage continued development and implementation of innovative solutions to improve equity in health and healing.

Fate of Hematopoiesis During Aging. What Do We Really Know, and What are its Implications?

There is an ongoing shift in demographics such that older persons will outnumber young persons in the coming years, and with it age-associated tissue attrition and increased diseases and disorders. There has been increased information on the association of the aging process with dysregulation of hematopoietic stem (HSC) and progenitor (HPC) cells, and hematopoiesis. This review provides an extensive up-to date summary on the literature of aged hematopoiesis and HSCs placed in context of potential artifacts of the collection and processing procedure, that may not be totally representative of the status of HSCs in their in vivo bone marrow microenvironment, and what the implications of this are for understanding aged hematopoiesis. This review covers a number of interactive areas, many of which have not been adequately explored. There are still many unknowns and mechanistic insights to be elucidated to better understand effects of aging on the hematopoietic system, efforts that will take multidisciplinary approaches, and that could lead to means to ameliorate at least some of the dysregulation of HSCs and HPCs associated with the aging process. Graphical Abstract.

Cell death signalling in virus infection

Apoptosis, necroptosis and pyroptosis represent three major regulated cell death modalities. Apoptosis features cell shrinkage, nuclear fragmentation and cytoplasm-blebbing. Necroptosis and pyroptosis exhibit osmotic imbalances in the cell accompanied by early membrane ruptures, which morphologically resembles necrosis. Importantly, these two lytic cell death forms facilitate the release of damage associated molecular patterns into the extracellular space leading to inflammatory response. Whereas, during apoptosis, the membrane integrity is preserved and the apoptotic cell is removed by neighbouring cells ensuring the avoidance of immune-stimulation. Viruses comprise a versatile group of intracellular pathogens, which elicit various strategies to infect and to propagate. Viruses are recognized by a myriad of pathogen recognition receptors in the human cells, which consequently lead to activation of the immune system and in certain circumstances cell-autonomous cell death. Importantly, the long-standing view that a cell death inducing capacity of a virus is equal to its pathogenic potential seems to be only partially valid. The altruistic cell death of an infected cell may serve the whole organism by ultimately curbing the way of virus manufacturing. In fact, several viruses express "anti-cell death" proteins to avoid this viral-defence mechanism. Conversely, some viruses hijack cell death pathways to selectively destroy cell populations in order to compromise the immune system of the host. This review discusses the pros and cons of virus induced cell death from the perspective of the host cells and attempts to provide a comprehensive overview of the complex network of cell death signalling in virus infection.

Inflammasomes and Childhood Autoimmune Diseases: A Review of Current Knowledge

Inflammasomes are multiprotein complexes capable of sensing pathogen-associated molecular patterns (PAMPs), danger-associated molecular patterns (DAMPs), and cellular perturbations. Upon stimulation, the inflammasomes activate the production of the pro-inflammatory cytokines IL-1β and IL-18 and induce gasdermin D-mediated pyroptosis. Dysregulated inflammasome signaling could lead to hyperinflammation in response to environmental triggers, thus contributing to the pathogenesis of childhood autoimmune/autoinflammatory diseases. In this review, we group childhood rheumatic diseases into the autoinflammation to autoimmunity spectrum and discuss about the involvement of inflammasomes in disease mechanisms. Genetic mutations in inflammasome components cause monogenic autoinflammatory diseases, while inflammasome-related genetic variants have been implicated in polygenic childhood rheumatic diseases. We highlight the reported associations of inflammasome signaling-related genetic polymorphisms/protein levels with pediatric autoimmune disease susceptibility and disease course. Furthermore, we discuss about the use of IL-1 receptor antagonist as an adjunctive therapy in several childhood autoimmune diseases, including macrophage activation syndrome (MAS) and multisystem inflammatory syndrome in children (MIS-C) related to COVID-19. A comprehensive multi-cohort comparison on inflammasome gene expression profile in different pediatric rheumatic diseases is needed to identify patient subsets that might benefit from the adjunctive therapy of IL-1β inhibitors.

SARS-CoV-2 and mitochondrial health: implications of lifestyle and ageing

Infection with SARs-COV-2 displays increasing fatality with age and underlying co-morbidity, in particular, with markers of the metabolic syndrome and diabetes, which seems to be associated with a "cytokine storm" and an altered immune response. This suggests that a key contributory factor could be immunosenescence that is both age-related and lifestyle-induced. As the immune system itself is heavily reliant on mitochondrial function, then maintaining a healthy mitochondrial system may play a key role in resisting the virus, both directly, and indirectly by ensuring a good vaccine response. Furthermore, as viruses in general, and quite possibly this new virus, have also evolved to modulate immunometabolism and thus mitochondrial function to ensure their replication, this could further stress cellular bioenergetics. Unlike most sedentary modern humans, one of the natural hosts for the virus, the bat, has to "exercise" regularly to find food, which continually provides a powerful adaptive stimulus to maintain functional muscle and mitochondria. In effect the bat is exposed to regular hormetic stimuli, which could provide clues on how to resist this virus. In this paper we review the data that might support the idea that mitochondrial health, induced by a healthy lifestyle, could be a key factor in resisting the virus, and for those people who are perhaps not in optimal health, treatments that could support mitochondrial function might be pivotal to their long-term recovery.

Understanding the complexities of SARS-CoV2 infection and its immunology: A road to immune-based therapeutics

Emerging infectious diseases always pose a threat to humans along with plant and animal life. SARS-CoV2 is the recently emerged viral infection that originated from Wuhan city of the Republic of China in December 2019. Now, it has become a pandemic. Currently, SARS-CoV2 has infected more than 27.74 million people worldwide, and taken 901,928 human lives. It was named first 'WH 1 Human CoV' and later changed to 2019 novel CoV (2019-nCoV). Scientists have established it as a zoonotic viral disease emerged from Chinese horseshoe bats, which do not develop a severe infection. For example, Rhinolophus Chinese horseshoe bats harboring severe acute respiratory syndrome-related coronavirus (SARSr-CoV) or SARSr-Rh-BatCoV appear healthy and clear the virus within 2-4 months period. The article introduces first the concept of EIDs and some past EIDs, which have affected human life. Next section discusses mysteries regarding SARS-CoV2 origin, its evolution, and human transfer. Third section describes COVID-19 clinical symptoms and factors affecting susceptibility or resistance. The fourth section introduces the SARS-CoV2 entry in the host cell, its replication, and the establishment of productive infection. Section five describes the host's immune response associated with asymptomatic, symptomatic, mild to moderate, and severe COVID-19. The subsequent seventh and eighth sections mention the immune status in COVID-19 convalescent patients and re-emergence of COVID-19 in them. Thereafter, the eighth section describes viral strategies to hijack the host antiviral immune response and generate the "cytokine storm". The ninth section describes about transgenic humane ACE2 (hACE2) receptor expressing mice to study immunity, drugs, and vaccines. The article ends with the development of different immunomodulatory and immunotherapeutics strategies, including vaccines waiting for their approval in humans as prophylaxis or treatment measures.

miR-98 Regulates TMPRSS2 Expression in Human Endothelial Cells: Key Implications for COVID-19

The two main co-factors needed by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to enter human cells are angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2). Here, we focused on the study of microRNAs that specifically target TMPRSS2. Through a bioinformatic approach, we identified miR-98-5p as a suitable candidate. Since we and others have shown that endothelial cells play a pivotal role in the pathogenesis of the coronavirus disease 2019 (COVID-19), we mechanistically validated miR-98-5p as a regulator of TMPRSS2 transcription in two different human endothelial cell types, derived from the lung and from the umbilical vein. Taken together, our findings indicate that TMPRSS2 represents a valid target in COVID-19 treatment, which may be achieved by specific non-coding-RNA approaches.

A Comprehensive Overview of the COVID-19 Literature: Machine Learning–Based Bibliometric Analysis (Preprint).. [DOI: 10.2196/preprints.23703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

BACKGROUND

Shortly after the emergence of COVID-19, researchers rapidly mobilized to study numerous aspects of the disease such as its evolution, clinical manifestations, effects, treatments, and vaccinations. This led to a rapid increase in the number of COVID-19–related publications. Identifying trends and areas of interest using traditional review methods (eg, scoping and systematic reviews) for such a large domain area is challenging.

OBJECTIVE

We aimed to conduct an extensive bibliometric analysis to provide a comprehensive overview of the COVID-19 literature.

METHODS

We used the COVID-19 Open Research Dataset (CORD-19) that consists of a large number of research articles related to all coronaviruses. We used a machine learning–based method to analyze the most relevant COVID-19–related articles and extracted the most prominent topics. Specifically, we used a clustering algorithm to group published articles based on the similarity of their abstracts to identify research hotspots and current research directions. We have made our software accessible to the community via GitHub.

RESULTS

Of the 196,630 publications retrieved from the database, we included 28,904 in our analysis. The mean number of weekly publications was 990 (SD 789.3). The country that published the highest number of COVID-19–related articles was China (2950/17,270, 17.08%). The highest number of articles were published in bioRxiv. Lei Liu affiliated with the Southern University of Science and Technology in China published the highest number of articles (n=46). Based on titles and abstracts alone, we were able to identify 1515 surveys, 733 systematic reviews, 512 cohort studies, 480 meta-analyses, and 362 randomized control trials. We identified 19 different topics covered among the publications reviewed. The most dominant topic was public health response, followed by clinical care practices during the COVID-19 pandemic, clinical characteristics and risk factors, and epidemic models for its spread.

CONCLUSIONS

We provide an overview of the COVID-19 literature and have identified current hotspots and research directions. Our findings can be useful for the research community to help prioritize research needs and recognize leading COVID-19 researchers, institutes, countries, and publishers. Our study shows that an AI-based bibliometric analysis has the potential to rapidly explore a large corpus of academic publications during a public health crisis. We believe that this work can be used to analyze other eHealth-related literature to help clinicians, administrators, and policy makers to obtain a holistic view of the literature and be able to categorize different topics of the existing research for further analyses. It can be further scaled (for instance, in time) to clinical summary documentation. Publishers should avoid noise in the data by developing a way to trace the evolution of individual publications and unique authors.