On the genetics and immunopathogenesis of COVID-19

Association between cyclin-dependent kinase inhibitor 2B antisense RNA 1 and zinc finger homeobox 3 gene polymorphisms and COVID-19 severity

BACKGROUND

There is no doubt about the cardiovascular complications of coronavirus disease 2019 (COVID-19). Several genetic studies have demonstrated an association between genetic variants in a region on chromosome 9p21 and in a region on chromosome 16q22 with myocardial infarction (MI) and atrial fibrillation (AF) accompanied by cerebral infarction (CI), respectively.

OBJECTIVES

MI and CI susceptibility in patients with CDKN2B-AS1 and ZFHX3 polymorphisms, respectively, may have an effect on COVID-19 severity. We aimed to investigate whether there is an association between the cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1) rs1333049 and zinc finger homeobox 3 (ZFHX3) rs2106261 single nucleotide polymorphisms (SNPs) and the degree of COVID-19 severity.

SUBJECTS AND METHODS

This current work was carried out on 360 subjects. They were classified into three groups: 90 severe COVID-19 cases, 90 moderate COVID-19 cases and 180 age- and gender-matched healthy controls. All subjects underwent genotyping of CDKN2B-AS1 (rs1333049) and ZFHX3 (rs2106261) by real-time PCR.

RESULTS

The frequency of G/C in CDKN2B-AS1 (rs1333049) was higher in severe and moderate COVID-19 patients than in controls (71.1% and 53.3% vs. 37.8%). The frequency of the C/C of CDKN2B-AS1 (rs1333049) was higher in moderate COVID-19 patients than in controls (26.7% vs. 13.3%). There were no significant differences regarding genotype frequency and allelic distribution of ZFHX3 (rs2106261) between COVID-19 patients and healthy controls.

CONCLUSION

CDKN2B-AS1 (rs1333049) gene polymorphism may play a role in determining the degree of COVID-19 severity. Further studies on its effect on cyclins and cyclin-dependent kinases (CDKs) [not measured in our study] may shed light on new treatment options for COVID-19.

Antiviral Nanobiologic Therapy Remodulates Innate Immune Responses to Highly Pathogenic Coronavirus

Highly pathogenic coronavirus (CoV) infection induces a defective innate antiviral immune response coupled with the dysregulated release of proinflammatory cytokines and finally results in acute respiratory distress syndrome (ARDS). A timely and appropriate triggering of innate antiviral response is crucial to inhibit viral replication and prevent ARDS. However, current medical countermeasures can rarely meet this urgent demand. Here, an antiviral nanobiologic named CoVR-MV is developed, which is polymerized of CoVs receptors based on a biomimetic membrane vesicle system. The designed CoVR-MV interferes with the viral infection by absorbing the viruses with maximized viral spike target interface, and mediates the clearance of the virus through its inherent interaction with macrophages. Furthermore, CoVR-MV coupled with the virus promotes a swift production and signaling of endogenous type I interferon via deregulating 7-dehydrocholesterol reductase (DHCR7) inhibition of interferon regulatory factor 3 (IRF3) activation in macrophages. These sequential processes re-modulate the innate immune responses to the virus, trigger spontaneous innate antiviral defenses, and rescue infected Syrian hamsters from ARDS caused by SARS-CoV-2 and all tested variants.

Role of T cells in severe COVID-19 disease, protection, and long term immunity

Infection with SARS-CoV-2 causes wide range of disease severities from asymptomatic to life-threatening disease. Understanding the contribution of immunological traits in immunity against SARS-CoV-2 and in protection against severe COVID-19 could result in effective measures to prevent development of severe disease. While the role of cytokines and antibodies has been thoroughly studied, this is not the case for T cells. In this review, the association between T cells and COVID-19 disease severity and protection upon reexposure is discussed. While infiltration of overactivated cytotoxic T cells might be harmful in the infected tissue, fast responding T cells are important in the protection against severe COVID-19. This protection could even be viable in the long term as long-living memory T cells seem to be stabilized and mutations do not appear to have a large impact on T cell responses. Thus, after vaccination and infections, memory T cells should be able to help prevent onset of severe disease for most cases. Considering this, it would be useful to add N or M proteins in vaccinations, alongside the S protein which is currently used, as this results in a broader T cell response.

Lung T cell response in COVID-19

The COVID-19 pandemic has shown the potentially devastating impact of novel respiratory infections worldwide. Insightful data obtained in the last years have shed light on the pathophysiology of SARS-CoV-2 infection and the role of the inflammatory response in driving both the resolution of the disease and uncontrolled deleterious inflammatory status in severe cases. In this mini-review, we cover some important aspects of the role of T cells in COVID-19 with a special focus on the local response in the lung. We focus on the reported T cell phenotypes in mild, moderate, and severe COVID-19, focusing on lung inflammation and on both the protective and damaging roles of the T cell response, also highlighting the open questions in the field.

Analysis of Gene Single Nucleotide Polymorphisms in COVID-19 Disease Highlighting the Susceptibility and the Severity towards the Infection

Many factors may influence the risk of being infected by SARS-CoV-2, the coronavirus responsible for coronavirus disease 2019 (COVID-19). Exposure to the virus cannot explain the variety of an individual's responses to the virus and the high differences of effect that the virus may cause to some. While a person's preexisting condition and their immune defenses have been confirmed to play a major role in the disease progression, there is still much to learn about hosts' genetic makeup towards COVID-19 susceptibility and risk. The host genetic makeup may have direct influence on the grade of predisposition and outcomes of COVID-19. In this study, we aimed to investigate the presence of relevant genetic single nucleotide polymorphisms (SNPs), the peripheral blood level of IL6, vitamin D and arterial blood gas (ABG) markers (pH, oxygen-SpO₂ and carbon dioxide-SpCO₂) on two groups, COVID-19 (n = 41, study), and the healthy (n = 43, control). We analyzed cytokine and interleukin genes in charge of both pro-inflammatory and immune-modulating responses and those genes that are considered involved in the COVID-19 progression and complications. Thus, we selected major genes, such as IL1β, IL1RN (IL-1 β and α receptor) IL6, IL6R (IL-6 receptor), IL10, IFNγ (interferon gamma), TNFα (tumor necrosis factor alpha), ACE2 (angiotensin converting enzyme), SERPINA3 (Alpha-1-Antiproteinase, Antitrypsin member of Serpin 3 family), VDR (vitamin D receptor Tak1, Bsm1 and Fok1), and CRP (c-reactive protein). Though more research is needed, these findings may give a better representation of virus pleiotropic activity and its relation to the immune system.

Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework

Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.

COVID-19 and neurological sequelae: Vitamin D as a possible neuroprotective and/or neuroreparative agent

SARS-CoV-2, the etiological agent of the current COVID-19 pandemic, belongs to a broad family of coronaviruses that also affect humans. SARS-CoV-2 infection usually leads to bilateral atypical pneumonia with significant impairment of respiratory function. However, the infectious capacity of SARS-CoV-2 is not limited to the respiratory system, but may also affect other vital organs such as the brain. The central nervous system is vulnerable to cell damage via direct invasion or indirect virus-related effects leading to a neuroinflammatory response, processes possibly associated with a decrease in the activity of angiotensin II converting enzyme (ACE2), the canonical cell-surface receptor for SARS-CoV-2. This enzyme regulates neuroprotective and neuroimmunomodulatory functions and can neutralize both inflammation and oxidative stress generated at the cellular level. Furthermore, there is evidence of an association between vitamin D deficiency and predisposition to the development of severe forms of COVID-19, with its possible neurological and neuropsychiatric sequelae: vitamin D has the ability to down-modulate the effects of neuroinflammatory cytokines, among other anti-inflammatory/immunomodulatory effects, thus attenuating harmful consequences of COVID-19. This review critically analyzes current evidence supporting the notion that vitamin D may act as a neuroprotective and neuroreparative agent against the neurological sequelae of COVID-19.

Probing the Immune System Dynamics of the COVID-19 Disease for Vaccine Designing and Drug Repurposing Using Bioinformatics Tools

The pathogenesis of COVID-19 is complicated by immune dysfunction. The impact of immune-based therapy in COVID-19 patients has been well documented, with some notable studies on the use of anti-cytokine medicines. However, the complexity of disease phenotypes, patient heterogeneity and the varying quality of evidence from immunotherapy studies provide problems in clinical decision-making. This review seeks to aid therapeutic decision-making by giving an overview of the immunological responses against COVID-19 disease that may contribute to the severity of the disease. We have extensively discussed theranostic methods for COVID-19 detection. With advancements in technology, bioinformatics has taken studies to a higher level. The paper also discusses the application of bioinformatics and machine learning tools for the diagnosis, vaccine design and drug repurposing against SARS-CoV-2.

Grammatical evolution-based design of SARS-CoV-2 main protease inhibitors

A series of SARS-CoV-2 main protease (SARS-CoV-2-M^pro) inhibitors were modeled using evolutive grammar algorithms. We have generated an automated program that finds the best candidate to inhibit the main protease, M^pro, of SARS-CoV-2. The candidates were constructed based on a pharmacophore model of the above-mentioned target; relevant moieties of such molecules were modified using data-basis sets with similar chemical behavior to the reference moieties. Additionally, we used the SMILES language to translate 3D chemical structures to 1D words; then, an evolutive grammar algorithm was used to explore the chemical space and obtain new candidates, which were evaluated via the binding energy of molecular coupling assays as an evaluation function. Finally, sixteen molecules were obtained in 3 runs of our program, three of which show promising binding properties as SARS-CoV-2-M^pro inhibitors. One of them, TTO, maintained its relevant binding properties during 100 ns molecular dynamics experiments. For this reason, TTO is the best candidate to inhibit SARS-CoV-2-M^pro. The software we developed for this contribution is available at the following URL: https://github.com/masotelof/GEMolecularDesign.

Complement activation induces excessive T cell cytotoxicity in severe COVID-19

Severe COVID-19 is linked to both dysfunctional immune response and unrestrained immunopathology, and it remains unclear whether T cells contribute to disease pathology. Here, we combined single-cell transcriptomics and single-cell proteomics with mechanistic studies to assess pathogenic T cell functions and inducing signals. We identified highly activated CD16+ T cells with increased cytotoxic functions in severe COVID-19. CD16 expression enabled immune-complex-mediated, T cell receptor-independent degranulation and cytotoxicity not found in other diseases. CD16+ T cells from COVID-19 patients promoted microvascular endothelial cell injury and release of neutrophil and monocyte chemoattractants. CD16+ T cell clones persisted beyond acute disease maintaining their cytotoxic phenotype. Increased generation of C3a in severe COVID-19 induced activated CD16+ cytotoxic T cells. Proportions of activated CD16+ T cells and plasma levels of complement proteins upstream of C3a were associated with fatal outcome of COVID-19, supporting a pathological role of exacerbated cytotoxicity and complement activation in COVID-19.

The Pathogenetic Dilemma of Post-COVID-19 Mucormycosis in India

There has been a surge of mucormycosis cases in India in the wake of the second wave of COVID-19 with more than 40000 cases reported. Mucormycosis in patients of COVID-19 in India is at variance to other countries where Aspergillus, Pneumocystis, and Candida have been reported to be the major secondary fungal pathogens. We discuss the probable causes of the mucormycosis epidemic in India. Whereas dysglycaemia and inappropriate steroid use have been widely suggested as tentative reasons, we explore other biological, iatrogenic, and environmental factors. The likelihood of a two-hit pathogenesis remains strong. We propose that COVID-19 itself provides the predisposition to invasive mucormycosis (first hit), through upregulation of GRP78 and downregulation of spleen tyrosine kinase involved in anti-fungal defense, as also through inhibition of CD8+ T-cell mediated immunity. The other iatrogenic and environmental factors may provide the second hit which may have resulted in the surge.

Potential long-term effects of SARS-CoV-2 infection on the pulmonary vasculature: a global perspective

The lungs are the primary target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, with severe hypoxia being the cause of death in the most critical cases. Coronavirus disease 2019 (COVID-19) is extremely heterogeneous in terms of severity, clinical phenotype and, importantly, global distribution. Although the majority of affected patients recover from the acute infection, many continue to suffer from late sequelae affecting various organs, including the lungs. The role of the pulmonary vascular system during the acute and chronic stages of COVID-19 has not been adequately studied. A thorough understanding of the origins and dynamic behaviour of the SARS-CoV-2 virus and the potential causes of heterogeneity in COVID-19 is essential for anticipating and treating the disease, in both the acute and the chronic stages, including the development of chronic pulmonary hypertension. Both COVID-19 and chronic pulmonary hypertension have assumed global dimensions, with potential complex interactions. In this Review, we present an update on the origins and behaviour of the SARS-CoV-2 virus and discuss the potential causes of the heterogeneity of COVID-19. In addition, we summarize the pathobiology of COVID-19, with an emphasis on the role of the pulmonary vasculature, both in the acute stage and in terms of the potential for developing chronic pulmonary hypertension. We hope that the information presented in this Review will help in the development of strategies for the prevention and treatment of the continuing COVID-19 pandemic.

In this Review, the authors discuss the potential causes of the heterogeneity of COVID-19 and summarize the pathobiology of the disease, with an emphasis on the role of the pulmonary vasculature in the acute stage and the potential for developing chronic pulmonary hypertension.

A thorough understanding of the dynamic behaviour of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential to understanding its heterogeneous effects on the pulmonary vasculature in patients with coronavirus disease 2019 (COVID-19).

The severity and clinical phenotype of COVID-19 are influenced by host factors, including socioeconomic factors and genetics.

Silent hypoxia is a major and independent cause of lung damage in COVID-19; the use of modern imaging techniques is proving to be very valuable in identifying silent hypoxia.

The pulmonary vascular system has a major role in the pathobiology of COVID-19.

Both COVID-19 and chronic pulmonary hypertension are global diseases with a complex interaction.

Small Extracellular Vesicles and COVID19-Using the "Trojan Horse" to Tackle the Giant

The COVID-19 pandemic is a global challenge, demanding researchers address different approaches in relation to prevention, diagnostics and therapeutics. Amongst the many tactics of tackling these therapeutic challenges, small extracellular vesicles (sEVs) or exosomes are emerging as a new frontier in the field of ameliorating viral infections. Exosomes are part of extracellular vesicles (EVs)-spherical biological structures with a lipid bilayer of a diameter of up to 5000 nm, which are released into the intercellular space by most types of eukaryotic cells, both in physiological and pathological states. EVs share structural similarities to viruses, such as small size, common mechanisms of biogenesis and mechanisms for cell entry. The role of EVs in promoting the viral spread by evading the immune response of the host, which is exhibited by retroviruses, indicates the potential for further investigation and possible manipulation of these processes when tackling the spread and treatment of COVID-19. The following paper introduces the topic of the use of exosomes in the treatment of viral infections, and presents the future prospects for the use of these EVs.

The D614G Virus Mutation Enhances Anosmia in COVID-19 Patients: Evidence from a Systematic Review and Meta-analysis of Studies from South Asia

The prevalence of chemosensory dysfunction in patients with COVID-19 varies greatly between populations. It is unclear whether such differences are due to factors at the level of the human host, or at the level of the coronavirus, or both. At the host level, the entry proteins which allow virus binding and entry have variants with distinct properties, and the frequency of such variants differs between ethnicities. At the level of the virus, the D614G mutation enhances virus entry to the host cell. Since the two virus strains (D614 and G614) coexisted in the first six months of the pandemic in most populations, it has been difficult to distinguish between contributions of the virus and contributions of the host for anosmia. To answer this question, we conducted a systematic review and meta-analysis of studies in South Asian populations when either the D614 or the G614 virus was dominant. We show that populations infected predominantly with the G614 virus had a much higher prevalence of anosmia (pooled prevalence of 31.8%) compared with the same ethnic populations infected mostly with the D614 virus strain (pooled anosmia prevalence of 5.3%). We conclude that the D614G mutation is a major contributing factor that increases the prevalence of anosmia in COVID-19, and that this enhanced effect on olfaction constitutes a previously unrecognized phenotype of the D614G mutation. The new virus strains that have additional mutations on the background of the D614G mutation can be expected to cause a similarly increased prevalence of chemosensory dysfunctions.

Public Health Interventions for COVID-19 Reduce Kawasaki Disease in Taiwan

Background: Kawasaki disease (KD) is a syndrome of unknown cause that results in high fever and coronary vasculitis in children. The incidence of KD increased in Taiwan over the past few decades. Taiwanese government executed domains of early screening, effective methods for isolation or quarantine, and digital technologies for identifying potential cases for the early elimination strategy for coronavirus disease 2019 (COVID-19) and public health interventions for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 pandemic, leading to an effective reduction of the risk of airway infections in children. The purpose of this study is to analyze whether those public health interventions reduce the incidence of KD in 2020. Methods: Patients with KD who visited Chang Gung Memorial Hospital (CGMH) between 1 January, 2018, and 31 December, 2020 were included for trend analysis. This is a retrospective case series study conducted at the CGMH, which consists of a network of seven hospital branches equipped with more than 10,000 beds in different areas of Taiwan. Results: Compared with the 2018 and 2019 databases, the incidence of KD decreased significantly by 30% and 31%, respectively (p < 0.05) in 2020, when public health interventions were comprehensively implemented in Taiwan. This result shows that the incidence of KD decreased during the COVID-19 pandemic in Taiwan without change of the presentation KD (typical or incomplete) and percentage of IVIG resistance in 2020. Conclusion: As public health interventions were carried out for the SARS-CoV-2 pandemic, the incidence of KD was significantly reduced in Taiwan. Is KD a preventable disease?

Melatonin interferes with COVID-19 at several distinct ROS-related steps

Recent studies have shown a correlation between COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and the distinct, exaggerated immune response titled "cytokine storm". This immune response leads to excessive production and accumulation of reactive oxygen species (ROS) that cause clinical signs characteristic of COVID-19 such as decreased oxygen saturation, alteration of hemoglobin properties, decreased nitric oxide (NO) bioavailability, vasoconstriction, elevated cytokines, cardiac and/or renal injury, enhanced D-dimer, leukocytosis, and an increased neutrophil to lymphocyte ratio. Particularly, neutrophil myeloperoxidase (MPO) is thought to be especially abundant and, as a result, contributes substantially to oxidative stress and the pathophysiology of COVID-19. Conversely, melatonin, a potent MPO inhibitor, has been noted for its anti-inflammatory, anti-oxidative, anti-apoptotic, and neuroprotective actions. Melatonin has been proposed as a safe therapeutic agent for COVID-19 recently, having been given with a US Food and Drug Administration emergency authorized cocktail, REGEN-COV2, for management of COVID-19 progression. This review distinctly highlights both how the destructive interactions of HOCl with tetrapyrrole rings may contribute to oxygen deficiency and hypoxia, vitamin B12 deficiency, NO deficiency, increased oxidative stress, and sleep disturbance, as well as how melatonin acts to prevent these events, thereby improving COVID-19 prognosis.

Coronavirus infection: An immunologists' perspective

Coronavirus infections are frequent viral infections in several species. As soon as the severe acute respiratory syndrome (SARS) appeared in the early 2000s, most of the research focused on pulmonary disease. However, disorders in immune response and organ dysfunctions have been documented. Elderly individuals with comorbidities exhibit worse outcomes in all the coronavirus that cause SARS. Disease severity in SARS-CoV-2 infection is related to severe inflammation and tissue injury, and effective immune response against the virus is still under analysis. ACE2 receptor expression and polymorphism, age, gender and immune genetics are factors that also play an essential role in patients' clinical features and immune responses and have been partially discussed. The present report aims to review the physiopathology of SARS-CoV-2 infection and propose new research topics to understand the complex mechanisms of viral infection and viral clearance.

Personality correlates of COVID-19 infection proclivity: Extraversion kills

The current research sought to shed light on the behavioral science that underlies the spread of SARS-CoV-2. We tested the extraversion hypothesis, which suggests that the sociability facet of extraversion may predispose people to becoming infected with the coronavirus via greater human-to-human contact. Since extraverts seek out social opportunities and seem less likely to follow containment measures related to social distancing, we hypothesized that people who have previously become infected would exhibit greater extraversion than would those who have not contracted the virus. We measured overall extraversion and three of its facets-sociability, assertiveness, and energy levels-as well as political orientation. We collected data from 217 adults, aged 40 and older, from the US and the UK, of whom 53 had had the virus at some point prior to the study, and 164 had not. Participants who had had COVID-19 were more dispositionally sociable and were also more conservative-leaning compared to participants who had never had COVID-19. Implications regarding the behavioral science underlying the current pandemic are discussed.

COVID-19 in Immunosuppressed Children

Following the spread of the SARS-CoV-2 infection and coronavirus disease 2019 (COVID-19) to a global pandemic, concerns have arisen for the disease impact in at-risk populations, especially in immunocompromised hosts. On the other hand, clinical studies have clarified that the COVID-19 clinical burden is mostly due to over-inflammation and immune-mediated multiorgan injury. This has led to downsizing the role of immunosuppression as a determinant of outcome, and early reports confirm the hypothesis that patients undergoing immunosuppressive treatments do not have an increased risk of severe COVID-19 with respect to the general population. Intriguingly, SARS-CoV-2 natural reservoirs, such as bats and mice, have evolved mechanisms of tolerance involving selection of genes optimizing viral clearance through interferon type I and III responses and also dampening inflammasome response and cytokine expression. Children exhibit resistance to COVID-19 severe manifestations, and age-related features in innate and adaptive response possibly explaining this difference are discussed. A competent recognition by the innate immune system and controlled pro-inflammatory signaling seem to be the pillars of an effective response and the premise for pathogen clearance in SARS-CoV-2 infection. Immunosuppression-if not associated with other elements of fragility-do not represent per se an obstacle to this competent/tolerant phenotype in children. Several reports confirm that children receiving immunosuppressive medications have similar clinical involvement and outcomes as the pediatric general population, indicating that maintenance treatments should not be interrupted in suspect or confirmed SARS-CoV-2 infection.

Will a little change do you good? A putative role of polymorphisms in COVID-19

An alarming disease caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) named COVID-19 has emerged as an unprecedented public health problem and ignited a world health crisis. As opposed to what was believed at the beginning of the pandemic, the virus has not only spread but persevere causing secondary waves and challenging the concept of herd immunity against viral infections. While the majority of SARS-CoV-2-infected individuals may remain asymptomatic, a fraction of individuals may develop low to high-grade severity signs and symptoms of COVID-19. The disease is multifactorial and can progress quickly, leading to severe complications and even death in a few days. Therefore, understanding the pre-existing factors for disease development has never been so pressing. In this scenario, the insights on the mechanisms underlying disease allied to the immune response developed during the viral invasion could shed light on novel predictive factors and prognostic tools for COVID-19 management and interventions. A recent genome-wide association study (GWAS) revealed several molecules that significantly impacted critically ill COVID-19 patients, leading to the core mechanisms of COVID-19 pathogenesis. Considering these findings and the fact that ACE-2 polymorphisms alone cannot explain disease progress and severity, this review aims at summarizing the most important and recent findings of the research and expert consensus of possible cytokine-related polymorphisms existing in the differential expression of paramount immune molecules that could be crucial for providing guidelines for decision-making and appropriate clinical management of COVID-19.

Coronavirus disease 2019 and the revival of passive immunization: Antibody therapy for inhibiting severe acute respiratory syndrome coronavirus 2 and preventing host cell infection: IUPHAR review: 31

The coronavirus disease 2019 (COVID-19) pandemic stimulated both the scientific community and healthcare companies to undertake an unprecedented effort with the aim of understanding the molecular mechanisms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and developing effective therapeutic solutions. The peculiar immune response triggered by this virus, which seems to last only few months, led to a search for alternatives such as passive immunization in addition to conventional vaccinations. Convalescent sera, monoclonal antibodies selected from the most potent neutralizing binders induced by the virus infection, recombinant human single-domain antibodies, and binders of variable scaffold and different origin have been tested alone or in combination exploiting monovalent, multivalent and multispecific formats. In this review, we analyse the state of the research in this field and present a summary of the ongoing projects finalized to identify suitable molecules for therapies based on passive immunization.

Prolonged humoral and cellular immunity in COVID-19-recovered patients

By the beginning of 2021, the battle against coronavirus disease 2019 (COVID-19) remains ongoing. Investigating the adaptive immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, in patients who have recovered from this disease could contribute to our understanding of the natural host immune response. We enrolled 38 participants in this study. 7 healthy participants and 31 COVID-19 patients who had recovered from COVID-19 and categorized them into 3 groups according to their previous clinical presentations: 10 moderate, 9 mild, and 12 asymptomatic. Flow cytometry analysis of peripheral lymphocyte counts in recovered patients showed significantly increased levels of CD4⁺ T cells in patients with a history of mild and moderate COVID-19 symptoms compared with those healthy individuals (p < 0.05 and p < 0.0001 respectively). whereas no significant difference was observed in the CD8⁺ T cell percentage in COVID-19-recovered patients compared with healthy individuals. Our study demonstrated that antibodies against the SARS-CoV-2 spike protein (anti-S) IgG antibody production could be observed in all recovered COVID-19 patients, regardless of whether they were asymptomatic (p < 0.05)or presented with mild (p < 0.0001) or moderate symptoms (p < 0.01). Anti-S IgG antibodies could be detected in participants up to 90 days post-infection. In conclusion, the lymphocyte levels in recovered patients were associated with the clinical presentation of the disease, and further analysis is required to investigate relationships between different clinical presentations and lymphocyte activation and function.

Ultramicronized Palmitoylethanolamide (um-PEA): A New Possible Adjuvant Treatment in COVID-19 patients

The Coronavirus Disease-19 (COVID-19) pandemic has caused more than 100,000,000 cases of coronavirus infection in the world in just a year, of which there were 2 million deaths. Its clinical picture is characterized by pulmonary involvement that culminates, in the most severe cases, in acute respiratory distress syndrome (ARDS). However, COVID-19 affects other organs and systems, including cardiovascular, urinary, gastrointestinal, and nervous systems. Currently, unique-drug therapy is not supported by international guidelines. In this context, it is important to resort to adjuvant therapies in combination with traditional pharmacological treatments. Among natural bioactive compounds, palmitoylethanolamide (PEA) seems to have potentially beneficial effects. In fact, the Food and Drug Administration (FDA) authorized an ongoing clinical trial with ultramicronized (um)-PEA as an add-on therapy in the treatment of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection. In support of this hypothesis, in vitro and in vivo studies have highlighted the immunomodulatory, anti-inflammatory, neuroprotective and pain-relieving effects of PEA, especially in its um form. The purpose of this review is to highlight the potential use of um-PEA as an adjuvant treatment in SARS-CoV-2 infection.

On the SARS-CoV-2 "Variolation Hypothesis": No Association Between Viral Load of Index Cases and COVID-19 Severity of Secondary Cases

Background: Emerging evidence supports the “variolation hypothesis” in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), but the derivative idea that the viral load of index cases may predict disease severity in secondary cases could be unsubstantiated. We assessed whether the prevalence of symptomatic infections, hospitalization, and deaths in household contacts of 2019 novel coronavirus disease (COVID-19) cases differed according to the SARS-CoV-2 PCR cycle threshold (Ct) from nasal-pharyngeal swab at diagnosis of linked index cases.

Methods: Cross-sectional study on household contacts of COVID-19 cases randomly sampled from all the infections diagnosed in March at our Microbiology Laboratory (Amedeo di Savoia, Turin). Data were retrospectively collected by phone interviews and from the Piedmont regional platform for COVID-19 emergency. Index cases were classified as high (HVl) and low viral load (LVl) according to two exploratory cut-offs of RdRp gene Ct value. Secondary cases were defined as swab confirmed or symptom based likely when not tested but presenting compatible clinical picture.

Results: One hundred thirty-two index cases of whom 87.9% symptomatic and 289 household contacts were included. The latter were male and Caucasian in 44.3 and 95.8% of cases, with a median age of 34 years (19–57). Seventy-four were swab confirmed and other 28 were symptom based likely secondary cases. Considering both, the contacts of HVl and LVl did not differ in the prevalence of symptomatic infections nor COVID-19-related hospitalization and death. No difference in median Ct of index cases between symptomatic and asymptomatic, hospitalized and not hospitalized, or deceased and survived secondary cases was found. Negative findings were confirmed after adjusting for differences in time between COVID-19 onset and swab collection of index cases (median 5 days) and after removing pediatric secondary cases.

Conclusions: The amount of SARS-CoV-2 of the source at diagnosis does not predict clinical outcomes of linked secondary cases. Considering the impelling release of assays for SARS-CoV-2 RNA exact quantification, these negative findings should inform clinical and public health strategies on how to interpret and use the data.

Kawasaki or Kawasaki-like disease? A debate on COVID-19 infection in children

Kawasaki disease (KD) is an inflammatory syndrome which is generally observed among children. Considering the significant number of COVID-19-positive children presenting with the manifestations of typical/atypical KD, it has been mentioned as a possible complication of COVID-19 infection among the children. However, many of the reported cases do not completely fill the clinical diagnostic criteria, which has made some researchers use the term “Kawasaki-like disease” instead of KD for this state. The current manuscript aims to review the key studies in the field, address the ongoing conflict, and indicate the objective requirements of the further studies.

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Kawasaki disease (KD) is a form of vasculitis, usually observed among children.

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Several COVID-19-positive children have presented typical/atypical KD.

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Many of the reported cases do not completely fill the clinical diagnostic criteria of KD.

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There is ongoing controversy on whether this is a form of KD or a novel inflammatory syndrome.