The Role of Type I Interferons in the Pathogenesis and Treatment of COVID-19

Dental Healthcare Amid the COVID-19 Pandemic

The hustle and bustle of the planet Earth have come to a halt thanks to the novel coronavirus. The virus has affected approximately 219 million people globally; taken the lives of 4.55 million patients as of September 2021; and created an ambiance of fear, social distancing, and economic instability. The purpose of this review article is to trace the historical origin and evolution of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). The virus is highly contagious with a unique feature of rapid mutations-the scientific research is paving the way for discoveries regarding novel coronavirus disease (COVID-19) diagnosis, features, prevention, and vaccination. The connections between the coronavirus pandemic and dental practices are essential because COVID-19 is transmitted by aerosols, fomites, and respiratory droplets, which are also produced during dental procedures, putting both the patient and the dentist at risk. The main emphasis of this paper is to highlight the psychological, economic, and social impact of this pandemic on dental practices throughout the world and under what circumstances and guidelines can dental health care be provided. In the current situation of the pandemic, an appropriate screening tool must be established either by using rapid molecular testing or saliva point-of-care technology, which will be effective in identifying as well as isolating the potential contacts and carriers in hopes to contain and mitigate infection. The blessing in disguise is that this virus has united the leaders, scientists, health care providers, and people of all professions from all around the world to fight against a common enemy.

Sex-Related Differences in Innate and Adaptive Immune Responses to SARS-CoV-2

Coronavirus disease 2019 (COVID-19) exhibits a sex bias with males showing signs of more severe disease and hospitalizations compared with females. The mechanisms are not clear but differential immune responses, particularly the initial innate immune response, between sexes may be playing a role. The early innate immune responses to SARS-CoV-2 have not been studied because of the gap in timing between the patient becoming infected, showing symptoms, and getting the treatment. The primary objective of the present study was to compare the response of dendritic cells (DCs) and monocytes from males and females to SARS-CoV-2, 24 h after infection. To investigate this, peripheral blood mononuclear cells (PBMCs) from healthy young individuals were stimulated in vitro with the virus. Our results indicate that PBMCs from females upregulated the expression of HLA-DR and CD86 on pDCs and mDCs after stimulation with the virus, while the activation of these cells was not significant in males. Monocytes from females also displayed increased activation than males. In addition, females secreted significantly higher levels of IFN-α and IL-29 compared with males at 24 h. However, the situation was reversed at 1 week post stimulation and males displayed high levels of IFN-α production compared with females. Further investigations revealed that the secretion of CXCL-10, a chemokine associated with lung complications, was higher in males than females at 24 h. The PBMCs from females also displayed increased induction of CTLs. Altogether, our results suggest that decreased activation of pDCs, mDCs, and monocytes and the delayed and prolonged IFN-α secretion along with increased CXCL-10 secretion may be responsible for the increased morbidity and mortality of males to COVID-19.

Mortality in critically ill patients with coronavirus disease 2019-associated pulmonary aspergillosis: A systematic review and meta-analysis

Reports of COVID-19 associated pulmonary aspergillosis (CAPA) are rising, but the associated mortality and factors affecting it are not well-characterised. We performed a systematic review including 20 peer-reviewed English language studies reporting mortality in CAPA published till 18 February 2021from PubMed, Ovid SP, Web of Science, Embase and CINHAL. The pooled mortality in CAPA was 51.2% (95% CI: 43.1-61.1, I2  = 38%). The leave one out sensitivity analysis and influential case diagnostics revealed one outlier and its exclusion resulted in a mortality estimate of 54% (95% CI: 45-62). Higher odds of mortality: 2.83 (95% CI: 1.8-4.5) were seen in CAPA compared to controls. No significant difference in various subgroups according to the country of study, the continent of study, income category of country and quality of the included study was seen. None of the host risk factors, mycological test results, therapy for COVID-19 and antifungal therapy affected mortality. Thus, patients with CAPA have a high probability of mortality and early diagnosis with prompt therapy must be ensured to optimally manage these patients. However, more prospective studies with global and multi-centre coordination may help to address CAPA in a better way.

Intranasal type I interferon treatment is beneficial only when administered before clinical signs onset in the SARS-CoV-2 hamster model

Impaired type I interferons (IFNs) production or signaling have been associated with severe COVID-19, further promoting the evaluation of recombinant type I IFNs as therapeutics against SARS-CoV-2 infection. In the Syrian hamster model, we show that intranasal administration of IFN-α starting one day pre-infection or one day post-infection limited weight loss and decreased viral lung titers. By contrast, intranasal administration of IFN-α starting at the onset of symptoms three days post-infection had no impact on the clinical course of SARS-CoV-2 infection. Our results provide evidence that early type I IFN treatment is beneficial, while late interventions are ineffective, although not associated with signs of enhanced disease.

Type I interferons are major antiviral effectors produced by the host in response to viral infections. Importantly, delayed or impaired type I IFN signalling response has been shown to correlate with severe COVID-19. These observations provided further impetus to test the administration of exogenous type I IFN as a treatment against SARS-CoV-2 infection in patients. However, studies using MERS-CoV or SARS-CoV infected mice demonstrated that type I interferon treatment was beneficial when administered early, but was ineffective and even caused deleterious immunopathology when administered at later stages of infection. It is therefore crucial to understand how the timing of the type I IFN treatments modulates their efficacy and safety against SARS-CoV-2. In this preclinical study using the SARS-CoV-2-infected Syrian hamster model, we showed that intranasal type I IFN treatment was beneficial only when administered before the onset of symptoms. Importantly, late treatment was ineffective but was not associated with deleterious effects. This study provides important information to interpret clinical trials showing no to modest effects of type I IFNs in COVID-19 patients.

SARS-CoV-2 suppresses IFNβ production mediated by NSP1, 5, 6, 15, ORF6 and ORF7b but does not suppress the effects of added interferon

Type I Interferons (IFN-Is) are a family of cytokines which play a major role in inhibiting viral infection. Resultantly, many viruses have evolved mechanisms in which to evade the IFN-I response. Here we tested the impact of expression of 27 different SARS-CoV-2 genes in relation to their effect on IFN production and activity using three independent experimental methods. We identified six gene products; NSP6, ORF6, ORF7b, NSP1, NSP5 and NSP15, which strongly (>10-fold) blocked MAVS-induced (but not TRIF-induced) IFNβ production. Expression of the first three of these SARS-CoV-2 genes specifically blocked MAVS-induced IFNβ-promoter activity, whereas all six genes induced a collapse in IFNβ mRNA levels, corresponding with suppressed IFNβ protein secretion. Five of these six genes furthermore suppressed MAVS-induced activation of IFNλs, however with no effect on IFNα or IFNγ production. In sharp contrast, SARS-CoV-2 infected cells remained extremely sensitive to anti-viral activity exerted by added IFN-Is. None of the SARS-CoV-2 genes were able to block IFN-I signaling, as demonstrated by robust activation of Interferon Stimulated Genes (ISGs) by added interferon. This, despite the reduced levels of STAT1 and phospho-STAT1, was likely caused by broad translation inhibition mediated by NSP1. Finally, we found that a truncated ORF7b variant that has arisen from a mutant SARS-CoV-2 strain harboring a 382-nucleotide deletion associating with mild disease (Δ382 strain identified in Singapore & Taiwan in 2020) lost its ability to suppress type I and type III IFN production. In summary, our findings support a multi-gene process in which SARS-CoV-2 blocks IFN-production, with ORF7b as a major player, presumably facilitating evasion of host detection during early infection. However, SARS-CoV-2 fails to suppress IFN-I signaling thus providing an opportunity to exploit IFN-Is as potential therapeutic antiviral drugs.

Predisposition of COVID-19 patients to secondary infections: set in stone or subject to change?

PURPOSE OF REVIEW

There likely are several predisposing factors to secondary infections in patients with Coronavirus disease 2019 (COVID-19), some of which may be preventable. The aim of this review is to explore the literature, summarize potential predisposing factors to secondary infections and their incidence. It also summarizes a variety of healthcare scenarios in which different kinds of secondary infections occur.

RECENT FINDINGS

Apart from immune dysregulation, severe resource limitations in healthcare settings have made COVID-19 units conducive to a variety of secondary infections. Long-term effect of excess antibiotic use in COVID-19 patients is yet to be studied. Very few studies have assessed secondary infections as the primary outcome measure making it difficult to know the true incidence. Mortality attributable to secondary infections in COVID-19 patients is also unclear.

SUMMARY

Incidence of secondary infections in COVID-19 patients is likely higher than what is reported in the literature. Well designed studies are needed to understand the incidence and impact of secondary infections in this patient population. Many of these may be preventable especially now, as personal protective equipment and other healthcare resources are recovering. Infection prevention and control (IPC) and antimicrobial stewardship programmes (ASP) must reassess current situation to correct any breaches that could potentially cause more harm in these already vulnerable patients as we brace for a future surge with another pandemic wave.

Successful management of post-COVID-19 acanthamoebic encephalitis

Acanthamoebic encephalitis is a rare and highly fatal disease that has no standard management protocol. Coronavirus disease 2019 (COVID-19) causes immune dysfunction and may predispose patients to this infection.

The present study describes successful management of acanthamoebic encephalitis in a young male who recently recovered from COVID-19 using a combination of medical and surgical approaches.

A combination of miltefosine with other agents with trophicidal and cysticidal activities should be used in the regimen. Surgical excision of the abscess should be undertaken whenever feasible.

Loss-of-function mutations in IFNAR2 in COVID-19 severe infection susceptibility

Recent COVID-19 (coronavirus disease 2019) host genetics studies suggest enrichment of mutations in genes involved in the regulation of type I and type III interferon (IFN) immunity in patients with severe COVID-19 infection. We performed whole-genome sequencing analysis of samples obtained from patients participating in the ongoing ODYSSEY phase 3 study of hospitalised patients with severe COVID-19 infection receiving supplemental oxygen support. We focused on burden testing of categories of rare and common loss-of-function (LOF) variants in all of the IFN pathway genes, specifically with MAF < 0.1% and MAF < 1%. In a model including LOF and missense variants (MAF < 1%), we report a significant signal in both INFAR1 and IFNAR2. We report carriers of rare variants in our COVID-19 cohort, including a stop-gain IFNAR2 (NM_000874:exon9:c.C966A:p.Y322X) amongst carriers of several other IFNAR rare nonsynonymous variants. Furthermore, we report an increased allelic frequency of common IFNAR2 variants in our data, reported also by the COVID-19 Host Genetics Initiative.

COVID-19: Failure of the DisCoVeRy Clinical Trial, and Now-New Hopes?

The DisCoVeRy clinical trial aimed at the evaluation of four treatments for patients suffering from severe to critical COVID-19: Hydroxychloroquine, eventually associated with azithromycin; the combination lopinavir/ritonavir; the combination with the addition of interferon β-1a; remdesivir. The trial was discontinued due to the lack of positive results. Meanwhile, many other potential options have been considered either to target the virus itself, the interactions with the host cells, or the cytokine storm frequently observed during the infection. Several of those options are briefly reviewed. They include vaccines, small molecules, antibodies, and stem cells.

SARS-CoV-2 infection in the Syrian hamster model causes inflammation as well as type I interferon dysregulation in both respiratory and non-respiratory tissues including the heart and kidney

COVID-19 (coronavirus disease 2019) caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection is a disease affecting several organ systems. A model that captures all clinical symptoms of COVID-19 as well as long-haulers disease is needed. We investigated the host responses associated with infection in several major organ systems including the respiratory tract, the heart, and the kidneys after SARS-CoV-2 infection in Syrian hamsters. We found significant increases in inflammatory cytokines (IL-6, IL-1beta, and TNF) and type II interferons whereas type I interferons were inhibited. Examination of extrapulmonary tissue indicated inflammation in the kidney, liver, and heart which also lacked type I interferon upregulation. Histologically, the heart had evidence of myocarditis and microthrombi while the kidney had tubular inflammation. These results give insight into the multiorgan disease experienced by people with COVID-19 and possibly the prolonged disease in people with post-acute sequelae of SARS-CoV-2 (PASC).

COVID-19 vaccine side effects: The positives about feeling bad

Side effects of SARS-CoV-2 vaccines are often troubling but may merely reflect transient production of type I interferons, a normal immune reaction to contact with pathogens.

Innate Immune Response to SARS-CoV-2 Infection: From Cells to Soluble Mediators

The vulnerability of humankind to SARS-CoV-2 in the absence of a pre-existing immunity, the unpredictability of the infection outcome, and the high transmissibility, broad tissue tropism, and ability to exploit and subvert the immune response pose a major challenge and are likely perpetuating the COVID-19 pandemic. Nevertheless, this peculiar infectious scenario provides researchers with a unique opportunity for studying, with the latest immunological techniques and understandings, the immune response in SARS-CoV-2 naïve versus recovered subjects as well as in SARS-CoV-2 vaccinees. Interestingly, the current understanding of COVID-19 indicates that the combined action of innate immune cells, cytokines, and chemokines fine-tunes the outcome of SARS-CoV-2 infection and the related immunopathogenesis. Indeed, the emerging picture clearly shows that the excessive inflammatory response against this virus is among the main causes of disease severity in COVID-19 patients. In this review, the innate immune response to SARS-CoV-2 infection is described not only in light of its capacity to influence the adaptive immune response towards a protective phenotype but also with the intent to point out the multiple strategies exploited by SARS-CoV-2 to antagonize host antiviral response and, finally, to outline inborn errors predisposing individuals to COVID-19 disease severity.

Discovery of Cyclic Peptide Ligands to the SARS-CoV-2 Spike Protein Using mRNA Display

The COVID-19 pandemic, caused by SARS-CoV-2, has led to substantial morbidity, mortality, and disruption globally. Cellular entry of SARS-CoV-2 is mediated by the viral spike protein, and affinity ligands to this surface protein have the potential for applications as antivirals and diagnostic reagents. Here, we describe the affinity selection of cyclic peptide ligands to the SARS-CoV-2 spike protein receptor binding domain (RBD) from three distinct libraries (in excess of a trillion molecules each) by mRNA display. We identified six high affinity molecules with dissociation constants (K D) in the nanomolar range (15-550 nM) to the RBD. The highest affinity ligand could be used as an affinity reagent to detect the spike protein in solution by ELISA, and the cocrystal structure of this molecule bound to the RBD demonstrated that it binds to a cryptic binding site, displacing a β-strand near the C-terminus. Our findings provide key mechanistic insight into the binding of peptide ligands to the SARS-CoV-2 spike RBD, and the ligands discovered in this work may find future use as reagents for diagnostic applications.

Inflammasome regulation in driving COVID-19 severity in humans and immune tolerance in bats

Coronaviruses (CoVs) are RNA viruses that cause human respiratory infections. Zoonotic transmission of the SARS‐CoV‐2 virus caused the recent COVID‐19 pandemic, which led to over 2 million deaths worldwide. Elevated inflammatory responses and cytotoxicity in the lungs are associated with COVID‐19 severity in SARS‐CoV‐2‐infected individuals. Bats, which host pathogenic CoVs, operate dampened inflammatory responses and show tolerance to these viruses with mild clinical symptoms. Delineating the mechanisms governing these host‐specific inflammatory responses is essential to understand host–virus interactions determining the outcome of pathogenic CoV infections. Here, we describe the essential role of inflammasome activation in determining COVID‐19 severity in humans and innate immune tolerance in bats that host several pathogenic CoVs. We further discuss mechanisms leading to inflammasome activation in human SARS‐CoV‐2 infection and how bats are molecularly adapted to suppress these inflammasome responses. We also report an analysis of functionally important residues of inflammasome components that provide new clues of bat strategies to suppress inflammasome signaling and innate immune responses. As spillover of bat viruses may cause the emergence of new human disease outbreaks, the inflammasome regulation in bats and humans likely provides specific strategies to combat the pathogenic CoV infections.

Circulating Type I Interferon Levels and COVID-19 Severity: A Systematic Review and Meta-Analysis

Introduction

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, resulting in a range of clinical manifestations and outcomes. Laboratory and immunological alterations have been considered as potential markers of disease severity and clinical evolution. Type I interferons (IFN-I), mainly represented by IFN-α and β, are a group of cytokines with an important function in antiviral responses and have played a complex role in COVID-19. Some studies have demonstrated that IFN-I levels and interferon response is elevated in mild cases, while other studies have noted this in severe cases. The involvement of IFN-I on the pathogenesis and outcomes of SARS-CoV-2 infection remains unclear. In this study, we summarize the available evidence of the association of plasma protein levels of type I IFN with the severity of COVID-19.

Methods

The PRISMA checklist guided the reporting of the data. A systematic search of the MEDLINE (PubMed), EMBASE, and Web of Science databases was performed up to March of 2021, looking for articles that evaluated plasma protein levels of IFN-I in mild, severe, or critical COVID-19 patients. Comparative meta-analyses with random effects were performed to compare the standardized mean differences in plasma protein levels of IFN-I of mild versus severe and mild versus critical patients. Meta-regressions were performed to test the moderating role of age, sex, time that the IFN-I was measured, and limit of detection of the assay used in the difference between the means.

Results

There was no significant difference in plasma levels of IFN-α when comparing between mild and severe patients (SMD = -0.236, 95% CI -0.645 to 0.173, p = 0.258, I2 = 82.11), nor when comparing between patients mild and critical (SMD = 0.203, 95% CI -0.363 to 0.770, p = 0.481, I2 = 64.06). However, there was a significant difference between healthy individuals and patients with mild disease (SMD = 0.447, 95% CI 0.085 to 0.810, p = 0.016, I2 = 62.89).

Conclusions

Peripheral IFN-α cannot be used as a severity marker as it does not determine the clinical status presented by COVID-19 patients.

Cellular Immune Response to COVID-19 and Potential Immune Modulators

Coronavirus disease 2019 (COVID-19) is a respiratory infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Droplets and contacts serve as the main route of transmission of SARS-CoV-2. The characteristic of the disease is rather heterogeneous, ranging from no symptoms to critical illness. The factors associated with the outcome of COVID-19 have not been completely characterized to date. Inspired by previous studies on the relevance of infectious diseases, viral and host factors related to clinical outcomes have been identified. The severity of COVID-19 is mainly related to host factors, especially cellular immune responses in patients. Patients with mild COVID-19 and improved patients with severe COVID-19 exhibit a normal immune response to effectively eliminate the virus. The immune response in patients with fatal severe COVID-19 includes three stages: normal or hypofunction, hyperactivation, and anergy. Eventually, the patients were unable to resist viral infection and died. Based on our understanding of the kinetics of immune responses during COVID-19, we suggest that type I interferon (IFN) could be administered to patients with severe COVID-19 in the hypofunctional stage, intravenous immunoglobulin (IVIG) and glucocorticoid therapy could be administered in the immune hyperactivation stage. In addition, low molecular weight heparin (LMWH) anticoagulation therapy and anti-infective therapy with antibiotics are recommended in the hyperactivation stage.

Type I Interferon Production of Plasmacytoid Dendritic Cells under Control

One of the most powerful and multifaceted cytokines produced by immune cells are type I interferons (IFNs), the basal secretion of which contributes to the maintenance of immune homeostasis, while their activation-induced production is essential to effective immune responses. Although, each cell is capable of producing type I IFNs, plasmacytoid dendritic cells (pDCs) possess a unique ability to rapidly produce large amounts of them. Importantly, type I IFNs have a prominent role in the pathomechanism of various pDC-associated diseases. Deficiency in type I IFN production increases the risk of more severe viral infections and the development of certain allergic reactions, and supports tumor resistance; nevertheless, its overproduction promotes autoimmune reactions. Therefore, the tight regulation of type I IFN responses of pDCs is essential to maintain an adequate level of immune response without causing adverse effects. Here, our goal was to summarize those endogenous factors that can influence the type I IFN responses of pDCs, and thus might serve as possible therapeutic targets in pDC-associated diseases. Furthermore, we briefly discuss the current therapeutic approaches targeting the pDC-type I IFN axis in viral infections, cancer, autoimmunity, and allergy, together with their limitations defined by the Janus-faced nature of pDC-derived type I IFNs.

Drugs used in the treatment of multiple sclerosis during COVID-19 pandemic: a critical viewpoint

Since COVID-19 has emerged as a word public health problem, attention has been focused on how immune-suppressive drugs used for the treatment of autoimmune disorders influence the risk for SARS-CoV-2 infection and the development of acute respiratory distress syndrome (ARDS). Here, we discuss the disease-modifying agents approved for the treatment of multiple sclerosis (MS) within this context. Interferon (IFN)-β1a and -1b, which display antiviral activity, could be protective in the early stage of COVID-19 infection, although SARS-CoV-2 may have developed resistance to IFNs. However, in the hyperinflammation stage, IFNs may become detrimental by facilitating macrophage invasion in the lung and other organs. Glatiramer acetate and its analogues should not interfere with the development of COVID-19 and may be considered safe. Teriflunomide, a first-line oral drug used in the treatment of relapsing-remitting MS (RRMS), may display antiviral activity by depleting cellular nucleotides necessary for viral replication. The other first-line drug, dimethyl fumarate, may afford protection against SARS-CoV-2 by activating the Nrf-2 pathway and reinforcing the cellular defenses against oxidative stress. Concern has been raised regarding the use of second-line treatments for MS during the COVID-19 pandemic. However, this concern is not always justified. For example, fingolimod might be highly beneficial during the hyperinflammatory stage of COVID-19 for a number of mechanisms, including the reinforcement of the endothelial barrier. Caution is suggested for the use of natalizumab, cladribine, alemtuzumab, and ocrelizumab, although MS disease recurrence after discontinuation of these drugs may overcome a potential risk for COVID-19 infection.

Serum Protein Profiling Reveals a Specific Upregulation of the Immunomodulatory Protein Progranulin in Coronavirus Disease 2019

Background

Severe courses of COVID-19 are associated with elevated levels of interleukin 6. However, there is a growing body of evidence pointing to a broad and more complex disorder of pro-inflammatory and anti-viral responses with disturbed interferon signaling in COVID-19.

Methods

In this prospective single-center registry, we included SARS-CoV-2 positive patients and patients with similar symptoms and severity of disease but negative for SARS-CoV-2 admitted to the emergency department and compared their serum protein expression profiles.

Results

Interleukin-6 abundance was similar in SARS-CoV-2 positive patients (n = 24) compared to SARS-CoV-2 negative control (n = 61). In contrast, we observed a specific upregulation of the immunomodulatory protein progranulin (GRN). High GRN abundance was associated with adverse outcomes and increased expression of interleukin-6 in COVID-19.

Conclusion

The data from this registry reveals that GRN is specifically upregulated in SARS-CoV-2 positive patients while interleukin-6 may serve as marker for disease severity. The potential of GRN as a biomarker and a possible impact of increased GRN expression on interferon signaling, virus elimination, and virus-induced lung tissue damage in COVID-19 should be further explored.

Blood Interferon-α Levels and Severity, Outcomes, and Inflammatory Profiles in Hospitalized COVID-19 Patients

Background: Deficient interferon responses have been proposed as one of the relevant mechanisms prompting severe manifestations of COVID-19.

Objective: To evaluate the interferon (IFN)-α levels in a cohort of COVID-19 patients in relation to severity, evolution of the clinical manifestations and immune/inflammatory profile.

Methods: This is prospective study recruiting consecutive hospitalized patients with respiratory failure associated with SARS-COV-2 infection and matched controls. After enrollment, patients were assessed every 7 ± 2 days for additional 2 consecutive visits, for a total of 21 days. The severity of the clinical condition was ranked based on the level of respiratory support required. At each time-point blood samples were obtained to assess immune cells and mediators by multiplex immunoassay.

Results: Fifty-four COVD-19 and 11 control patients matched for severity were enrolled. At recruitment, lower levels of blood IFN-α were found in COVID-19 patients compared to controls (3.8-fold difference, p < 0.01). Improvements in COVID-19 severity were paralleled by a significant increase of blood IFN-α levels. A significant increase in blood IFN-α was found over the study period in survivors (70% of the study population). A similar trend was found for blood IFN-β with IFN-β levels below the threshold of detectability in a substantial proportion of subjects. Significantly higher values of blood lymphocytes and lower levels of IL-10 were found at each time point in patients who survived compared to patients who died. In patients who clinically improved and survived during the study, we found an inverse association between IL-10 and IFN-α levels.

Conclusion: The study identifies a blood immune profile defined by deficient IFN-α levels associated with increased IL-10 expression in patients progressing to severe/life threatening COVID-19 conditions, suggesting the involvement of immunological pathways that could be target of pharmacological intervention.

Clinical Trial Registration:ClinicalTrials.gov identifier NCT04343053.

The Role of Immunogenetics in COVID-19

Coronavirus disease 2019 (COVID-19) is induced by SARS-CoV-2 and may arise as a variety of clinical manifestations, ranging from an asymptomatic condition to a life-threatening disease associated with cytokine storm, multiorgan and respiratory failure. The molecular mechanism behind such variability is still under investigation. Several pieces of experimental evidence suggest that genetic variants influencing the onset, maintenance and resolution of the immune response may be fundamental in predicting the evolution of the disease. The identification of genetic variants behind immune system reactivity and function in COVID-19 may help in the elaboration of personalized therapeutic strategies. In the frenetic look for universally shared treatment plans, those genetic variants that are common to other diseases/models may also help in addressing future research in terms of drug repurposing. In this paper, we discuss the most recent updates about the role of immunogenetics in determining the susceptibility to and the history of SARS-CoV-2 infection. We propose a narrative review of available data, speculating about lessons that we have learnt from other viral infections and immunosenescence, and discussing what kind of aspects of research should be deepened in order to improve our knowledge of how host genetic variability impacts the outcome for COVID-19 patients.

At the Crossroads: COVID-19 and Immune-Checkpoint Blockade for Cancer

The immunomodulatory effects of immune-checkpoint blockade (ICB) therapy for cancer may act at the crossroads between the need to increase antiviral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and to decrease the inflammatory responses in severe cases of coronavirus disease 2019 (COVID-19). There is evidence from preclinical models that blocking programmed death receptor 1 (PD1) protects against RNA virus infections, which suggests that patients with cancer receiving ICB may have lower rates of viral infection. However, given the heterogeneity of patient characteristics, this would be difficult to demonstrate using population-based registries or in clinical trials. Most studies of the impact of ICB therapy on the course of COVID-19 have centered on studying its potential detrimental impact on the course of the COVID-19 infection, in particular on the development of the most severe inflammatory complications. This is a logical concern as it is becoming clear that complications of COVID-19 such as severe respiratory distress syndrome are related to interferon signaling, which is the pathway that leads to expression of the PD1 ligand PD-L1. Therefore, PD1/PD-L1 ICB could potentially increase inflammatory processes, worsening the disease course for patients. However, review of the current evidence does not support the notion that ICB therapy worsens complications from COVID-19, and we conclude that it supports the continued use of ICB therapy during the COVID-19 pandemic provided that we now collect data on the effects of such therapy on COVID-19 vaccination.

COVID-19 and Dentistry in 72 Questions: An Overview of the Literature

The outbreak of Coronavirus Disease 2019 (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has significantly affected the dental care sector. Dental professionals are at high risk of being infected, and therefore transmitting SARS-CoV-2, due to the nature of their profession, with close proximity to the patient's oropharyngeal and nasal regions and the use of aerosol-generating procedures. The aim of this article is to provide an update on different issues regarding SARS-CoV-2 and COVID-19 that may be relevant for dentists. Members of the French National College of Oral Biology Lecturers ("Collège National des EnseignantS en Biologie Orale"; CNESBO-COVID19 Task Force) answered seventy-two questions related to various topics, including epidemiology, virology, immunology, diagnosis and testing, SARS-CoV-2 transmission and oral cavity, COVID-19 clinical presentation, current treatment options, vaccine strategies, as well as infection prevention and control in dental practice. The questions were selected based on their relevance for dental practitioners. Authors independently extracted and gathered scientific data related to COVID-19, SARS-CoV-2 and the specific topics using scientific databases. With this review, the dental practitioners will have a general overview of the COVID-19 pandemic and its impact on their practice.

Differential roles of RIG-I-like receptors in SARS-CoV-2 infection

The retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated protein 5 (MDA5) are the major viral RNA sensors that are essential for activation of antiviral immune responses. However, their roles in severe acute respiratory syndrome (SARS)-causing coronavirus (CoV) infection are largely unknown. Herein we investigate their functions in human epithelial cells, the primary and initial target of SARS-CoV-2, and the first line of host defense. A deficiency in MDA5 ( MDA5 -/- ), RIG-I or mitochondrial antiviral signaling protein (MAVS) greatly enhanced viral replication. Expression of the type I/III interferons (IFN) was upregulated following infection in wild-type cells, while this upregulation was severely abolished in MDA5 -/- and MAVS -/- , but not in RIG-I -/- cells. Of note, ACE2 expression was ~2.5 fold higher in RIG-I -/- than WT cells. These data demonstrate a dominant role of MDA5 in activating the type I/III IFN response to SARS-CoV-2, and an IFN-independent anti-SARS-CoV-2 role of RIG-I.

Shared and Unique Features of Human Interferon-Beta and Interferon-Alpha Subtypes

Type I interferons (IFN-I) were first discovered as an antiviral factor by Isaacs and Lindenmann in 1957, but they are now known to also modulate innate and adaptive immunity and suppress proliferation of cancer cells. While much has been revealed about IFN-I, it remains a mystery as to why there are 16 different IFN-I gene products, including IFNβ, IFNω, and 12 subtypes of IFNα. Here, we discuss shared and unique aspects of these IFN-I in the context of their evolution, expression patterns, and signaling through their shared heterodimeric receptor. We propose that rather than investigating responses to individual IFN-I, these contexts can serve as an alternative approach toward investigating roles for IFNα subtypes. Finally, we review uses of IFNα and IFNβ as therapeutic agents to suppress chronic viral infections or to treat multiple sclerosis.

Understanding the implications of SARS-CoV-2 re-infections on immune response milieu, laboratory tests and control measures against COVID-19

Several months after the emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), cases of re-infection after recovery were reported. The extent and duration of protective immunity after SARS-CoV-2 infection is not fully understood. As such, the possibility of re-infection with SARS-CoV-2. Furthermore, cases of re-infection were mainly due to different variants or mutant SARS-CoV-2. Following the fast and pandemic-scale spread of COVID-19, mutations in SARS-CoV-2 have raised new diagnostic challenges which include the redesign of the oligonucleotide sequences used in RT-PCR assays to avoid potential primer-sample mismatches, and decrease sensitivities. Since the initial wave of the pandemic, some regions had experienced fresh outbreaks, predisposing people to be susceptible to SARS-CoV-2 re-infection. Hence, this article sought to offer detailed biology of SARS-CoV-2 re-infections and their implications on immune response milieu, diagnostic laboratory tests and control measures against COVID-19.

Potential Risks and Benefits of Multiple Sclerosis Immune Therapies in the COVID-19 Era: Clinical and Immunological Perspectives

Coronavirus SARS-CoV2 has emerged as one of the greatest infectious disease health challenges in a century. Patients with multiple sclerosis (MS) have a particular vulnerability to infections through their use of immunosuppressive disease-modifying therapies (DMTs). Specific DMTs pose particular risk based on their mechanisms of action (MOA). As a result, patients require individualized approaches to starting new treatments and continuation of therapy. Additionally, vaccinations must be considered carefully, and individuals on long-term B cell-depleting therapies may have diminished immune responses to vaccination, based on preserved T cells and diminished but present antibody titers to influenza vaccines. We review the immunology behind these treatments and their impact on COVID-19, as well as the current recommendations for best practices for use of DMTs in patients with MS.

Potent in vitro anti-SARS-CoV-2 activity by gallinamide A and analogues via inhibition of cathepsin L

The emergence of SARS-CoV-2 in late 2019, and the subsequent COVID-19 pandemic, has led to substantial mortality, together with mass global disruption. There is an urgent need for novel antiviral drugs for therapeutic or prophylactic application. Cathepsin L is a key host cysteine protease utilized by coronaviruses for cell entry and is recognized as a promising drug target. The marine natural product, gallinamide A and several synthetic analogues, were identified as potent inhibitors of cathepsin L activity with IC ₅₀ values in the picomolar range. Lead molecules possessed selectivity over cathepsin B and other related human cathepsin proteases and did not exhibit inhibitory activity against viral proteases Mpro and PLpro. We demonstrate that gallinamide A and two lead analogues potently inhibit SARS-CoV-2 infection in vitro , with EC ₅₀ values in the nanomolar range, thus further highlighting the potential of cathepsin L as a COVID-19 antiviral drug target.