Immune asynchrony in COVID-19 pathogenesis and potential immunotherapies

HERV-W ENV transcription in B cells predicting symptomatic COVID-19 and risk for long COVID can express a full-length protein despite stop codon in mRNA from chromosome X via a ribosome readthrough

The human genome comprises 8 % of endogenous retroviruses (HERVs). Though HERVS contribute to physiological functions, copies retained pathogenic potential. The HERV-W ENV protein was shown expressed in patients with worse COVID-19 symptoms and post-COVID syndrome. A significant detection of the mRNA encoding HERV-W ENV from patients with COVID-19 in B cells from RNAseq reads obtained from peripheral blond mononuclear cells. This data stratified with increased COVID-19 symptoms or with post-acute sequelae of COVID-19 (long COVID) after 3 months. The HERV-W ENV-U3R RNA was confirmed to display the best alignment with chromosome X ERVWE2 locus. However, a stop codon precluding its translation was re-addressed after recent understandings of ribosome readthrough mechanisms. Experimental results evidenced that this HERV gene can effectively express a full-length protein in the presence of molecules allowing translation via a readthrough mechanism at the ribosome level. Results not only confirm HERV-W ENV RNA origin in these patients but show for the first time how a defective HERV copy can be translated into a complete protein when specific factors make it possible at the ribosome level. The present proof of concept now requires further studies to identify the factors involved in this newly understood mechanism, following SARS-CoV-2 exposure.

A murine model of DC-SIGN humanization exhibits increased susceptibility against SARS-CoV-2

To generate a new murine model for virus, DC-SIGN gene in murine was humanized. In this study, we successfully generated a humanized C57BL/6N mouse model expressing human DC-SIGN (hDC-SIGN) using CRISPR/Cas9 technology, and evaluated its characters and susceptibility to virus. The humanized mice could survival as usual, and with normal physiological index just like the wild-type mice. Whereas, we found significant differences in the intestinal flora and metabolic profiles between wild-type mice and humanized mice. Following intranasal infection with SARS-CoV-2, hDC-SIGN mice exhibited significantly increased viral loads in the lungs and nasal turbinates, along with more severe lung damage. This phenomenon may be associated with differential lipid metabolism and Fcγ receptor-mediated phagocytosis in two mouse models. This study provides a useful tool for investigating the mechanisms of coronavirus infection and potential drug therapies against novel coronavirus.

Mapping the vast landscape of multisystem complications of COVID-19: Bibliometric analysis

Background

With the rapid global spread of COVID-19, it has become evident that the virus can lead to multisystem complications, leading to a significant increase in related publications. Bibliometrics serves as a valuable tool for identifying highly cited literature and research hotspots within specific areas.

Objective

The aim of this study is to identify current research hotspots and future trends in COVID-19 complications.

Methods

The dataset was obtained from the Web of Science Core Collection, covering COVID-19 complications from December 8, 2019, to October 31, 2022. Various aspects, including publication general information, authors, journals, co-cited authors, co-cited references, research hotspots, and future trends, were subjected to analysis. Visual analysis was conducted using VOSviewer, The Online Analysis Platform of Literature Metrology, and Charticulator.

Results

There were 4597 articles in the study. The top three countries with the most published articles are the USA (n = 1350, 29.4 %), China (n = 765, 16.6 %), and Italy (n = 623, 13.6 %). USA and China have the closest collaborative relationship. The institute with the largest number of publications is Huazhong University of Science and Technology, followed by Harvard Medical School. Nevertheless, half of the top 10 institutes belong to the USA. "Rezaei, Nima" published 13 articles and ranked first, followed by "Yaghi, Shadi" with 12 articles and "Frontera, Jennifer" with 12 articles. The journal with the largest number of publications is "Journal of Clinical Medicine". The top 3 co-cited authors are "Zhou, Fei", "Guan, Wei-Jie", "Huang, Chaolin". The top 3 co-cited references addressed COVID-19's clinical features in China and noticed that COVID-19 patients had a wide range of complications. We also list four research hotspots.

Conclusions

This study conducted a bibliometric visual analysis of the literature on COVID-19 complications and summarized the current research hotspots. This study may provide valuable insights into the complications of COVID-19.

IFN-γ decreases PD-1 in T lymphocytes from convalescent COVID-19 patients via the AKT/GSK3β signaling pathway

Post-COVID-19 syndrome may be associated with the abnormal immune status. Compared with the unexposed age-matched elder group, PD-1 in the CD8+ T cells from recovered COVID-19 patients was significantly lower. IFN-γ in the plasma of COVID-19 convalescent patients was increased, which inhibited PD-1 expression in CD8+ T cells from COVID-19 convalescent patients. scRNA-seq bioinformatics analysis revealed that AKT/GSK3β may regulate the INF-γ/PD-1 axis in CD8+ T cells from COVID-19 convalescent patients. In parallel, an IFN-γ neutralizing antibody reduced AKT and increased GSK3β in PBMCs. An AKT agonist (SC79) significantly decreased p-GSK3β. Moreover, AKT decreased PD-1 on CD8+ T cells, and GSK3β increased PD-1 on CD8+ T cells according to flow cytometry analysis. Collectively, we demonstrated that recovered COVID-19 patients may develop long COVID. Increased IFN-γ in the plasma of recovered Wuhan COVID-19 patients contributed to PD-1 downregulation on CD8+ T cells by regulating the AKT/GSK3β signaling pathway.

Immune and cytokine alterations and RNA-sequencing analysis in gestational tissues from pregnant women after recovery from COVID-19

BACKGROUND

COVID-19 is a global pandemic. Understanding the immune responses in pregnant women recovering from COVID-19 may suggest new therapeutic approaches.

METHODS

We performed a cross-sectional study between March 1, 2020, and September 1, 2020. Participants were assigned into the convalescent COVID-19 group if they had a previous COVID-19 infection during pregnancy or the healthy control group. RNA-Seq was performed on human umbilical cord mesenchymal stem cells (hUMSCs) and human amniotic mesenchymal stem cells (hAMSCs). Immunohistochemical staining, cytokine testing, lymphocyte subset analysis, RNA-Seq, and functional analyses were performed on the placental and umbilical cord blood (UCB) and compared between the two groups.

RESULTS

A total of 40 pregnant women were enrolled, with 13 in the convalescent group and 27 in the control group. There were 1024, 46, and 32 differentially expressed genes (DEGs) identified in the placental tissue, hUMSCs, and hAMSCs between the convalescent and control groups, respectively. Enrichment analysis showed those DEGs were associated with immune homeostasis, antiviral activity, cell proliferation, and tissue repair. Levels of IL-6, TNF-α, total lymphocyte counts, B lymphocytes, Tregs percentages, and IFN-γ expressing CD4+ and CD8+ T cells were statistically different between two groups (p ≤ 0.05). ACE2 and TMPRSS2 expressed on the placenta were not different between the two groups (p > 0.05).

CONCLUSION

Multiple changes in immune responses occurred in the placental tissue, hUMSCs, and hAMSCs after maternal recovery from COVID-19, which might imply their protective roles against COVID-19 infection.

A Review: The Potential Involvement of Growth Arrest-Specific 6 and Its Receptors in the Pathogenesis of Lung Damage and in Coronavirus Disease 2019

The tyrosine kinase receptors of the TAM family-Tyro3, Axl and Mer-and their main ligand Gas6 (growth arrest-specific 6) have been implicated in several human diseases, having a particularly important role in the regulation of innate immunity and inflammatory response. The Gas6/TAM system is involved in the recognition of apoptotic debris by immune cells and this mechanism has been exploited by viruses for cell entry and infection. Coronavirus disease 2019 (COVID-19) is a multi-systemic disease, but the lungs are particularly affected during the acute phase and some patients may suffer persistent lung damage. Among the manifestations of the disease, fibrotic abnormalities have been observed among the survivors of COVID-19. The mechanisms of COVID-related fibrosis remain elusive, even though some parallels may be drawn with other fibrotic diseases, such as idiopathic pulmonary fibrosis. Due to the still limited number of scientific studies addressing this question, in this review we aimed to integrate the current knowledge of the Gas6/TAM axis with the pathophysiological mechanisms underlying COVID-19, with emphasis on the development of a fibrotic phenotype.

Cell-Based Biomaterials for Coronavirus Disease 2019 Prevention and Therapy

Coronavirus disease 2019 (COVID-19) continues to threaten human health, economic development, and national security. Although many vaccines and drugs have been explored to fight against the major pandemic, their efficacy and safety still need to be improved. Cell-based biomaterials, especially living cells, extracellular vesicles, and cell membranes, offer great potential in preventing and treating COVID-19 owing to their versatility and unique biological functions. In this review, the characteristics and functions of cell-based biomaterials and their biological applications in COVID-19 prevention and therapy are described. First the pathological features of COVID-19 are summarized, providing enlightenment on how to fight against COVID-19. Next, the classification, organization structure, characteristics, and functions of cell-based biomaterials are focused on. Finally, the progress of cell-based biomaterials in overcoming COVID-19 in different aspects, including the prevention of viral infection, inhibition of viral proliferation, anti-inflammation, tissue repair, and alleviation of lymphopenia are comprehensively described. At the end of this review, a look forward to the challenges of this aspect is presented.

Serum proteomics hint at an early T-cell response and modulation of SARS-CoV-2-related pathogenic pathways in COVID-19-ARDS treated with Ruxolitinib

Background

Acute respiratory distress syndrome (ARDS) in corona virus disease 19 (COVID-19) is triggered by hyperinflammation, thus providing a rationale for immunosuppressive treatments. The Janus kinase inhibitor Ruxolitinib (Ruxo) has shown efficacy in severe and critical COVID-19. In this study, we hypothesized that Ruxo's mode of action in this condition is reflected by changes in the peripheral blood proteome.

Methods

This study included 11 COVID-19 patients, who were treated at our center's Intensive Care Unit (ICU). All patients received standard-of-care treatment and n = 8 patients with ARDS received Ruxo in addition. Blood samples were collected before (day 0) and on days 1, 6, and 10 of Ruxo treatment or, respectively, ICU admission. Serum proteomes were analyzed by mass spectrometry (MS) and cytometric bead array.

Results

Linear modeling of MS data yielded 27 significantly differentially regulated proteins on day 1, 69 on day 6 and 72 on day 10. Only five factors (IGLV10-54, PSMB1, PGLYRP1, APOA5, WARS1) were regulated both concordantly and significantly over time. Overrepresentation analysis revealed biological processes involving T-cells only on day 1, while a humoral immune response and complement activation were detected at day 6 and day 10. Pathway enrichment analysis identified the NRF2-pathway early under Ruxo treatment and Network map of SARS-CoV-2 signaling and Statin inhibition of cholesterol production at later time points.

Conclusion

Our results indicate that the mechanism of action of Ruxo in COVID-19-ARDS can be related to both known effects of this drug as a modulator of T-cells and the SARS-CoV-2-infection.

Defective antifungal immunity in patients with COVID-19

The COVID-19 pandemic has placed a huge strain on global healthcare and been a significant cause of increased morbidity and mortality, particularly in at-risk populations. This disease attacks the respiratory systems and causes significant immune dysregulation in affected patients creating a perfect opportunity for the development of invasive fungal disease (IFD). COVID-19 infection can instill a significant, poorly regulated pro-inflammatory response. Clinically induced immunosuppression or pro-inflammatory damage to mucosa facilitate the development of IFD and Aspergillus, Mucorales, and Candida infections have been regularly reported throughout the COVID-19 pandemic. Corticosteroids and immune modulators are used in the treatment of COVID-19. Corticosteroid use is also a risk factor for IFD, but not the only reason for IFD in COVID -19 patients. Specific dysregulation of the immune system through functional exhaustion of Natural killer (NK) cells and T cells has been observed in COVID-19 through the expression of the exhaustion markers NK-G2A and PD-1. Reduced fungicidal activity of neutrophils from COVID-19 patients indicates that immune dysfunction/imbalance are important risk factors for IFD. The COVID-19 pandemic has significantly increased the at-risk population for IFD. Even if the incidence of IFD is relatively low, the size of this new at-risk population will result in a substantial increase in the overall, annual number of IFD cases. It is important to understand how and why certain patients with COVID-19 developed increased susceptibility to IFD, as this will improve our understanding of risk of IFD in the face of future pandemics but also in a clinical era of increased clinical immuno-suppression/modulation.

Infection and chronic disease activate a brain-muscle signaling axis that regulates muscle performance

Infections and neurodegenerative diseases induce neuroinflammation, but affected individuals often show a number of non-neural symptoms including muscle pain and muscle fatigue. The molecular pathways by which neuroinflammation causes pathologies outside the central nervous system (CNS) are poorly understood, so we developed three models to investigate the impact of neuroinflammation on muscle performance. We found that bacterial infection, COVID-like viral infection, and expression of a neurotoxic protein associated with Alzheimer' s disease promoted the accumulation of reactive oxygen species (ROS) in the brain. Excessive ROS induces the expression of the cytokine Unpaired 3 (Upd3) in insects, or its orthologue IL-6 in mammals, and CNS-derived Upd3/IL-6 activates the JAK/Stat pathway in skeletal muscle. In response to JAK/Stat signaling, mitochondrial function is impaired and muscle performance is reduced. Our work uncovers a brain-muscle signaling axis in which infections and chronic diseases induce cytokine-dependent changes in muscle performance, suggesting IL-6 could be a therapeutic target to treat muscle weakness caused by neuroinflammation.

COVID-19: imbalanced cell-mediated immune response drives to immunopathology

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses an imminent threat to humanity. SARS-CoV-2 invades host cells, causing a failure of host immune recognition. Instead of an effective antiviral immunological response after SARS-CoV-2 invasion, the cascading pathological syndrome of COVID-19, especially in severe disease, is exacerbated by an overt inflammatory response and the suppression of SARS-CoV-2–specific immune responses. As is known, excessive inflammation leads to pathophysiological changes in virus-infected tissues or organs, manifested by imbalanced immune responses, cytokine storm, and aggressive neutrophil activation, ultimately leading to lung damage, such as alveolar damage, endotheliitis, and fluid overload. However, the triggers and consequences of a disruption to immune system homeostasis and the underlying mechanisms of uncontrolled immunopathology following viral infection remain unclear. Here, we review the dynamic and systemic immune progression from an imbalance in cell-mediated immune responses to COVID-19 lung injury. Our understanding of key mechanisms involved in pathogenesis is critical for the development of therapeutic agents and to optimize therapeutic strategies.

Colchicine for the treatment of COVID-19: short path from theory to practice

Colchicine is an alkaloid isolated from plants of the Colchicum genus. Colchicine has been used for thousands of years and remains one of the few drugs whose use remains relevant today. The therapeutic use of colchicine is widely known for gout, familial Mediterranean fever, Behcet’s disease, cardiovascular diseases (pericarditis, coronary heart disease, pericarditis, after coronary artery bypass grafting, etc.) and other diseases and is due to anti-inflammatory effects, which are based, including , inhibition of NLRP3 inflammasome and interleukin (IL)-1β production. The mechanisms of anti-inflammatory action of colchicine are diverse. It is primarily an inhibitor of mitosis and microtubule assembly. Colchicine destroys the structure of microtubules and reduces the elasticity and relaxation of neutrophils, thereby preventing the extravasation of neutrophils from blood vessels to the site of inflammation. Systemic inflammation is also a hallmark of coronavirus disease (COVID-19), which develops immunological disorders accompanied by the  production of  a large number of  pro-inflammatory cytokines, including interleukin-1. Coronavirus disease 2019 (COVID-19), which has become the most urgent medical problem in the world in the last 2 years, given the mechanisms of inflammation similar to rheumatic diseases, is also considered a disease with the potential effectiveness of colchicine treatment. SARS-CoV-2 vaccines also have a trigger factor for the development of an exacerbation of arthritis. On average, colchicine use was associated with a 47% reduction in post-vaccination arthritis. This article provides an update on the mechanisms of action and current experience with colchicine in COVID-19, including in patients with microcrystalline arthritis.

JAK Inhibition as a New Treatment Strategy for Patients with COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic continues to spread globally. The rapid dispersion of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 drives an urgent need for effective treatments, especially for patients who develop severe pneumonia. The excessive and uncontrolled release of pro-inflammatory cytokines has proved to be an essential factor in the rapidity of disease progression, and some cytokines are significantly associated with adverse outcomes. Most of the upregulated cytokines signal through the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway. Therefore, blocking the exaggerated release of cytokines, including IL-2, IL-6, TNF-α, and IFNα/β/γ, by inhibiting JAK/STAT signaling will, presumably, offer favorable pharmacodynamics and present an attractive prospect. JAK inhibitors (JAKi) can also inhibit members of the numb-associated kinase (NAK) family, including AP2-associated kinase 1 (AAK1) and cyclin G-associated kinase (GAK), which regulate the angiotensin-converting enzyme 2 (ACE-2) transmembrane protein and are involved in host viral endocytosis. According to the data released from current clinical trials, JAKi treatment can effectively control the dysregulated cytokine storm and improve clinical outcomes regarding mortality, ICU admission, and discharge. There are still some concerns surrounding thromboembolic events, opportunistic infection such as herpes zoster virus reactivation, and repression of the host's type-I IFN-dependent immune repair for both viral and bacterial infection. However, the current JAKi clinical trials of COVID-19 raised no new safety concerns except a slightly increased risk of herpes virus infection. In the updated WHO guideline, Baricitinb is strongly recommended as an alternative to IL-6 receptor blockers, particularly in combination with corticosteroids, in patients with severe or critical COVID-19. Future studies will explore the application of JAKi to COVID-19 treatment in greater detail, such as the optimal timing and course of JAKi treatment, individualized medication strategies based on pharmacogenomics, and the effect of combined medications.

The role of IL-1 family of cytokines and receptors in pathogenesis of COVID-19

A global pandemic has erupted as a result of the new brand coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This pandemic has been consociated with widespread mortality worldwide. The antiviral immune response is an imperative factor in confronting the recent coronavirus disease 2019 (COVID-19) infections. Meantime, cytokines recognize as crucial components in guiding the appropriate immune pathways in the restraining and eradication of the virus. Moreover, SARS-CoV-2 can induce uncontrolled inflammatory responses characterized by hyper-inflammatory cytokine production, which causes cytokine storm and acute respiratory distress syndrome (ARDS). As excessive inflammatory responses are contributed to the severe stage of the COVID-19 disease, therefore, the pro-inflammatory cytokines are regarded as the Achilles heel during COVID-19 infection. Among these cytokines, interleukin (IL-) 1 family cytokines (IL-1, IL-18, IL-33, IL-36, IL-37, and IL-38) appear to have a strong inflammatory role in severe COVID-19. Hence, understanding the underlying inflammatory mechanism of these cytokines during infection is critical for reducing the symptoms and severity of the disease. Here, the possible mechanisms and pathways involved in inflammatory immune responses are discussed.

Myeloid-derived suppressor cells in COVID-19: A review

Coronavirus disease 2019 (COVID-19) is a potentially life-threatening infection characterized by excessive inflammation, coagulation disorders and organ damage. A dysregulated myeloid cell compartment is one of the most striking immunopathologic signatures of this newly emerged infection. A growing number of studies are reporting on the expansion of myeloid cells with immunoregulatory activities in the periphery and airways of COVID-19 patients. These cells share phenotypic and functional similarities with myeloid-derived suppressor cells (MDSCs), which were first described in cancer patients. MDSCs are a heterogeneous population of pathologically activated myeloid cells that exert immunosuppressive activities against mainly effector T cells. The increased frequency of these cells in COVID-19 patients suggests that they are involved in immune regulation during this infection. In this article, we review the current findings on MDSCs in COVID-19 and discuss the complex role of these cells in the immunopathology of COVID-19.

The S1 Subunit of the SARS-CoV-2 Spike Protein Activates Human Monocytes to Produce Cytokines Linked to COVID-19: Relevance to Galectin-3

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rapidly evolved into a pandemic –the likes of which has not been experienced in 100 years. While novel vaccines show great efficacy, and therapeutics continue to be developed, the persistence of disease, with the concomitant threat of emergent variants, continues to impose massive health and socioeconomic issues worldwide. Studies show that in susceptible individuals, SARS-CoV-2 infection can rapidly progress toward lung injury and acute respiratory distress syndrome (ARDS), with evidence for an underlying dysregulated innate immune response or cytokine release syndrome (CRS). The mechanisms responsible for this CRS remain poorly understood, yet hyper-inflammatory features were also evident with predecessor viruses within the β-coronaviridae family, namely SARS-CoV-1 and the Middle East Respiratory Syndrome (MERS)-CoV. It is further known that the spike protein (S) of SARS-CoV-2 (as first reported for other β-coronaviruses) possesses a so-called galectin-fold within the N-terminal domain of the S1 subunit (S1-NTD). This fold (or pocket) shows structural homology nearly identical to that of human galectin-3 (Gal-3). In this respect, we have recently shown that Gal-3, when associated with epithelial cells or anchored to a solid phase matrix, facilitates the activation of innate immune cells, including basophils, DC, and monocytes. A synthesis of these findings prompted us to test whether segments of the SARS-CoV-2 spike protein might also activate innate immune cells in a manner similar to that observed in our Gal-3 studies. Indeed, by immobilizing S components onto microtiter wells, we show that only the S1 subunit (with the NTD) activates human monocytes to produce a near identical pattern of cytokines as those reported in COVID-19-related CRS. In contrast, both the S1-CTD/RBD, which binds ACE2, and the S2 subunit (stalk), failed to mediate the same effect. Overall, these findings provide evidence that the SARS-CoV-2 spike protein can activate monocytes for cytokines central to COVID-19, thus providing insight into the innate immune mechanisms underlying the CRS and the potential for therapeutic interventions.

D-dimer and CoV-2 spike-immune complexes contribute to the production of PGE2 and proinflammatory cytokines in monocytes

An overreactive inflammatory response and coagulopathy are observed in patients with severe form of COVID-19. Since increased levels of D-dimer (DD) are associated with coagulopathy in COVID-19, we explored whether DD contributes to the aberrant cytokine responses. Here we show that treatment of healthy human monocytes with DD induced a dose dependent increase in production of pyrogenic mediator, Prostaglandin E2 (PGE2) and inflammatory cytokines, IL-6 and IL-8. The DD-induced PGE2 and inflammatory cytokines were enhanced significantly by co-treatment with immune complexes (IC) of SARS CoV-2 recombinant S protein or of pseudovirus containing SARS CoV-2 S protein (PVCoV-2) coated with spike-specific chimeric monoclonal antibody (MAb) containing mouse variable and human Fc regions. The production of PGE2 and cytokines in monocytes activated with DD and ICs was sensitive to the inhibitors of β2 integrin and FcγRIIa, and to the inhibitors of calcium signaling, Mitogen-Activated Protein Kinase (MAPK) pathway, and tyrosine-protein kinase. Importantly, strong increase in PGE2 and in IL-6/IL-8/IL-1β cytokines was observed in monocytes activated with DD in the presence of IC of PVCoV-2 coated with plasma from hospitalized COVID-19 patients but not from healthy donors. The IC of PVCoV-2 with convalescent plasma induced much lower levels of PGE2 and cytokines compared with plasma from hospitalized COVID-19 patients. PGE2 and IL-6/IL-8 cytokines produced in monocytes activated with plasma-containing IC, correlated well with the levels of spike binding antibodies and not with neutralizing antibody titers. Our study suggests that a combination of high levels of DD and high titers of spike-binding antibodies that can form IC with SARS CoV-2 viral particles might accelerate the inflammatory status of lung infiltrating monocytes leading to increased lung pathology in patients with severe form of COVID-19.

Coagulation factor V is a T-cell inhibitor expressed by leukocytes in COVID-19

Clotting Factor V (FV) is primarily synthesized in the liver and when cleaved by thrombin forms pro-coagulant Factor Va (FVa). Using whole blood RNAseq and scRNAseq of peripheral blood mononuclear cells, we find that FV mRNA is expressed in leukocytes, and identify neutrophils, monocytes, and T regulatory cells as sources of increased FV in hospitalized patients with COVID-19. Proteomic analysis confirms increased FV in circulating neutrophils in severe COVID-19, and immunofluorescence microscopy identifies FV in lung-infiltrating leukocytes in COVID-19 lung disease. Increased leukocyte FV expression in severe disease correlates with T-cell lymphopenia. Both plasma-derived and a cleavage resistant recombinant FV, but not thrombin cleaved FVa, suppress T-cell proliferation in vitro. Anticoagulants that reduce FV conversion to FVa, including heparin, may have the unintended consequence of suppressing the adaptive immune system.

Cancer Occurrence as the Upcoming Complications of COVID-19

Previous studies suggested that patients with comorbidities including cancer had a higher risk of mortality or developing more severe forms of COVID-19. The interaction of cancer and COVID-19 is unrecognized and potential long-term effects of COVID-19 on cancer outcome remain to be explored. Furthermore, whether COVID-19 increases the risk of cancer in those without previous history of malignancies, has not yet been studied. Cancer progression, recurrence and metastasis depend on the complex interaction between the tumor and the host inflammatory response. Extreme proinflammatory cytokine release (cytokine storm) and multi-organ failure are hallmarks of severe COVID-19. Besides impaired T-Cell response, elevated levels of cytokines, growth factors and also chemokines in the plasma of patients in the acute phase of COVID-19 as well as tissue damage and chronic low-grade inflammation in "long COVID-19" syndrome may facilitate cancer progression and recurrence. Following a systemic inflammatory response syndrome, some counterbalancing compensatory anti-inflammatory mechanisms will be activated to restore immune homeostasis. On the other hand, there remains the possibility of the integration of SARS- CoV-2 into the host genome, which potentially may cause cancer. These mechanisms have also been shown to be implicated in both tumorigenesis and metastasis. In this review, we are going to focus on potential mechanisms and the molecular interplay, which connect COVID-19, inflammation, and immune-mediated tumor progression that may propose a framework to understand the possible role of COVID-19 infection in tumorgenesis and cancer progression.

Scoping insight on antiviral drugs against COVID-19

Background

COVID-19 is an ongoing viral pandemic produced by SARS-CoV-2. In light of in vitro efficacy, several medications were repurposed for its management. During clinical use, many of these medications produced inconsistent results or had varying limitations.

Objective

The purpose of this literature review is to explain the variable efficacy or limitations of Lopinavir/Ritonavir, Remdesivir, Hydroxychloroquine, and Favipiravir in clinical settings.

Method

A study of the literature on the pharmacodynamics (PD), pharmacokinetics (PK), safety profile, and clinical trials through academic databases using relevant search terms.

Results & discussion

The efficacy of an antiviral drug against COVID-19 is associated with its ability to achieve therapeutic concentration in the lung and intestinal tissues. This efficacy depends on the PK properties, particularly protein binding, volume of distribution, and half-life. The PK and PD of the model drugs need to be integrated to predict their limitations.

Conclusion

Current antiviral drugs have varying pharmacological constraints that may associate with limited efficacy, especially in severe COVID-19 patients, or safety concerns.

Clinical features and predictors of mortality among hospitalized patients with COVID-19 in Niger

Introduction

COVID-19 has spread across the African continent, including Niger. Yet very little is known about the phenotype of people who tested positive for COVID-19. In this humanitarian crises region, we aimed at characterizing variation in clinical features among hospitalized patients with COVID-19-like syndrome and to determine predictors associated with COVID-19 mortality among those with confirmed COVID-19.

Methods

The study was a retrospective nationwide cohort of hospitalized patients isolated for COVID-19 infection, using the health data of the National Health Information System from 19 March 2020 (onset of the pandemic) to 17 November 2020. All hospitalized patients with COVID-19-like syndrome at admission were included. A Cox-proportional regression model was built to identify predictors of in-hospital death among patients with confirmed COVID-19.

Results

Sixty-five percent (472/729) of patients hospitalized with COVID-19 like syndrome tested positive for SARS-CoV-2 among which, 70 (15%) died. Among the patients with confirmed COVID-19 infection, age was significantly associated with increased odds of reporting cough (adjusted odds ratio [aOR] 1.02; 95% confidence interval [CI] 1.01–1.03) and fever/chills (aOR 1.02; 95% CI 1.02–1.04). Comorbidity was associated with increased odds of presenting with cough (aOR 1.59; 95% CI 1.03–2.45) and shortness of breath (aOR 2.03; 95% CI 1.27–3.26) at admission. In addition, comorbidity (adjusted hazards ratio [aHR] 2.04; 95% CI 2.38–6.35), shortness of breath at baseline (aHR 2.04; 95% CI 2.38–6.35) and being 60 years or older (aHR 5.34; 95% CI 3.25–8.75) increased the risk of COVID-19 mortality two to five folds.

Conclusion

Comorbidity, shortness of breath on admission, and being aged 60 years or older are associated with a higher risk of death among patients hospitalized with COVID-19 in a humanitarian crisis setting. While robust prospective data are needed to guide evidence, our data might aid intensive care resource allocation in Niger.

Platelets contribute to disease severity in COVID-19

OBJECTIVE

Heightened inflammation, dysregulated immunity, and thrombotic events are characteristic of hospitalized COVID-19 patients. Given that platelets are key regulators of thrombosis, inflammation, and immunity they represent prime candidates as mediators of COVID-19-associated pathogenesis. The objective of this study was to understand the contribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to the platelet phenotype via phenotypic (activation, aggregation) and transcriptomic characterization.

APPROACH AND RESULTS

In a cohort of 3915 hospitalized COVID-19 patients, we analyzed blood platelet indices collected at hospital admission. Following adjustment for demographics, clinical risk factors, medication, and biomarkers of inflammation and thrombosis, we find platelet count, size, and immaturity are associated with increased critical illness and all-cause mortality. Bone marrow, lung tissue, and blood from COVID-19 patients revealed the presence of SARS-CoV-2 virions in megakaryocytes and platelets. Characterization of COVID-19 platelets found them to be hyperreactive (increased aggregation, and expression of P-selectin and CD40) and to have a distinct transcriptomic profile characteristic of prothrombotic large and immature platelets. In vitro mechanistic studies highlight that the interaction of SARS-CoV-2 with megakaryocytes alters the platelet transcriptome, and its effects are distinct from the coronavirus responsible for the common cold (CoV-OC43).

CONCLUSIONS

Platelet count, size, and maturity associate with increased critical illness and all-cause mortality among hospitalized COVID-19 patients. Profiling tissues and blood from COVID-19 patients revealed that SARS-CoV-2 virions enter megakaryocytes and platelets and associate with alterations to the platelet transcriptome and activation profile.

SARS-CoV-2 Spike Protein and Its Receptor Binding Domain Promote a Proinflammatory Activation Profile on Human Dendritic Cells

Dendritic cells (DCs) are the most potent antigen-presenting cells, and their function is essential to configure adaptative immunity and avoid excessive inflammation. DCs are predicted to play a crucial role in the clinical evolution of the infection by the severe acute respiratory syndrome (SARS) coronavirus (CoV)-2. DCs interaction with the SARS-CoV-2 Spike protein, which mediates cell receptor binding and subsequent fusion of the viral particle with host cell, is a key step to induce effective immunity against this virus and in the S protein-based vaccination protocols. Here we evaluated human DCs in response to SARS-CoV-2 S protein, or to a fragment encompassing the receptor binding domain (RBD) challenge. Both proteins increased the expression of maturation markers, including MHC molecules and costimulatory receptors. DCs interaction with the SARS-CoV-2 S protein promotes activation of key signaling molecules involved in inflammation, including MAPK, AKT, STAT1, and NFκB, which correlates with the expression and secretion of distinctive proinflammatory cytokines. Differences in the expression of ACE2 along the differentiation of human monocytes to mature DCs and inter-donor were found. Our results show that SARS-CoV-2 S protein promotes inflammatory response and provides molecular links between individual variations and the degree of response against this virus.

Pharmacological inhibition of Mint3 attenuates tumour growth, metastasis, and endotoxic shock

Hypoxia-inducible factor-1 (HIF-1) plays essential roles in human diseases, though its central role in oxygen homoeostasis hinders the development of direct HIF-1-targeted pharmacological approaches. Here, we surveyed small-molecule compounds that efficiently inhibit the transcriptional activity of HIF-1 without affecting body homoeostasis. We focused on Mint3, which activates HIF-1 transcriptional activity in limited types of cells, such as cancer cells and macrophages, by suppressing the factor inhibiting HIF-1 (FIH-1). We identified naphthofluorescein, which inhibited the Mint3–FIH-1 interaction in vitro and suppressed Mint3-dependent HIF-1 activity and glycolysis in cancer cells and macrophages without evidence of cytotoxicity in vitro. In vivo naphthofluorescein administration suppressed tumour growth and metastasis without adverse effects, similar to the genetic depletion of Mint3. Naphthofluorescein attenuated inflammatory cytokine production and endotoxic shock in mice. Thus, Mint3 inhibitors may present a new targeted therapeutic option for cancer and inflammatory diseases by avoiding severe adverse effects.

Sakomoto et al. identify naphthofluorescein as a mint3 inhibitor that disrupts the Mint3–FIH-1 interaction and attenuates HIF-1 activity. In vivo experiments in mice reveal a reduction in tumor growth with attenuated inflammatory cytokine production and endotoxic shock, presenting an option for targeted therapies for cancer and inflammatory diseases that avoid severe adverse effects.

COVID-19 Lung Pathogenesis in SARS-CoV-2 Autopsy Cases

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major public health issue. COVID-19 is considered an airway/multi-systemic disease, and demise has been associated with an uncontrolled immune response and a cytokine storm in response to the virus. However, the lung pathology, immune response, and tissue damage associated with COVID-19 demise are poorly described and understood due to safety concerns. Using post-mortem lung tissues from uninfected and COVID-19 deadly cases as well as an unbiased combined analysis of histology, multi-viral and host markers staining, correlative microscopy, confocal, and image analysis, we identified three distinct phenotypes of COVID-19-induced lung damage. First, a COVID-19-induced hemorrhage characterized by minimal immune infiltration and large thrombus; Second, a COVID-19-induced immune infiltration with excessive immune cell infiltration but no hemorrhagic events. The third phenotype correspond to the combination of the two previous ones. We observed the loss of alveolar wall integrity, detachment of lung tissue pieces, fibroblast proliferation, and extensive fibrosis in all three phenotypes. Although lung tissues studied were from lethal COVID-19, a strong immune response was observed in all cases analyzed with significant B cell and poor T cell infiltrations, suggesting an exhausted or compromised immune cellular response in these patients. Overall, our data show that SARS-CoV-2-induced lung damage is highly heterogeneous. These individual differences need to be considered to understand the acute and long-term COVID-19 consequences.

Alterations in Phenotypes and Responses of T Cells Within 6 Months of Recovery from COVID-19: A Cohort Study

The COVID-19 pandemic, caused by the SARS-CoV-2 infection, is a global health crisis. While many patients have clinically recovered, little is known about long-term alterations in T cell responses of COVID-19 convalescents. In this study, T cell responses in peripheral blood mononuclear cells of a long-time COVID-19 clinically recovered (20-26 weeks) cohort (LCR) were measured via flow cytometry and ELISpot. The T cell responses of LCR were comparatively analyzed against an age and sex matched short-time clinically recovered (4-9 weeks) cohort (SCR) and a healthy donor cohort (HD). All volunteers were recruited from Wuhan Jinyintan Hospital, China. Phenotypic analysis showed that activation marker PD-1 expressing on CD4+ T cells of LCR was still significantly lower than that of HD. Functional analysis indicated that frequencies of Tc2, Th2 and Th17 in LCR were comparable to those of HD, but Tc17 was higher than that of HD. In LCR, compared to the HD, there were fewer IFN-γ producing T cells but more IL-2 secreting T cells. In addition, the circulating Tfh cells in LCR were still slightly lower compared to HD, though the subsets composition had recovered. Remarkably, SARS-CoV-2 specific T cell responses in LCR were comparable to that of SCR. Collectively, T cell responses experienced long-term alterations in phenotype and functional potential of LCR cohort. However, after clinical recovery, SARS-CoV-2 specific T cell responses could be sustained at least for six months, which may be helpful in resisting re-infection.

Single-cell transcriptome identifies FCGR3B upregulated subtype of alveolar macrophages in patients with critical COVID-19

Understanding host cell heterogeneity is critical for unraveling disease mechanism. Utilizing large-scale single-cell transcriptomics, we analyzed multiple tissue specimens from patients with life-threatening COVID-19 pneumonia, compared with healthy controls. We identified a subtype of monocyte-derived alveolar macrophages (MoAMs) where genes associated with severe COVID-19 comorbidities are significantly upregulated in bronchoalveolar lavage fluid of critical cases. FCGR3B consistently demarcated MoAM subset in different samples from severe COVID-19 cohorts and in CCL3L1-upregulated cells from nasopharyngeal swabs. In silico findings were validated by upregulation of FCGR3B in nasopharyngeal swabs of severe ICU COVID-19 cases, particularly in older patients and those with comorbidities. Additional lines of evidence from transcriptomic data and in vivo of severe COVID-19 cases suggest that FCGR3B may identify a specific subtype of MoAM in patients with severe COVID-19 that may present a novel biomarker for screening and prognosis, as well as a potential therapeutic target.

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Association of MoAM subtype with severe COVID-19 cases presented with comorbidities

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Upregulated FCGR3B in CCL3L1 positive MoAM cells in severe COVID-19 cases

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Upregulated FCGR3B within MoAM subtype as a potential marker for COVID-19 severity

Host gene variability and SARS-CoV-2 infection: A review article

SARS-CoV-2 is a global threat that influenced healthcare systems around the world. This virus caused an infection in humans with different clinical signs and syndromes, severity, and mortality. The key components of the COVID-19 molecular pathogenesis are coronavirus entry and replication, antigen presentation, humoral and cellular immunity, cytokine storm, coronavirus immune evasion. The analysis of recent literature displayed possible molecular targets in the key components of the COVID-19 pathogenesis. Some of these targets might have gene polymorphisms that influenced the COVID-19 course. Unfortunately, several findings are still putative or extrapolated from SARS and MERS experimental investigations or clinical trials. We systematised original data about gene polymorphisms of possible molecular targets and associations with the COVID-19 course. Most data were obtained for angiotensin-converting enzymes 1 and 2, TMPRSS2 gene polymorphisms. Only a few results were found for gene polymorphisms of adhesion molecules, interferon system components, cytokines, and transcriptional factors, oxidative stress and metabolic molecules, as well as haemocoagulation. Understanding the host gene variability and its associations with COVID-19 can provide insights into the disease pathogenesis, individual susceptibility to SARS-CoV-2 infection, severity, complications, and mortality prognosis for the disease. Besides, these data might help in the identification of appropriate targets for intervention.

Could Immunonutrition Help in the Fight against COVID-19 in Cancer Patient?

The rapid and widespread global pandemic of 2019 coronavirus disease (COVID-19) has had unprecedented negative health and economic impacts. Immune responses play a key role in the development of COVID-19, including the disruption of immune balance and cytokine storms caused by excessive inflammatory responses. Due to the effects of cancer itself and treatment, patients often accompanied by immunosuppression appear to be a susceptible population for COVID-19. Worryingly, COVID-19 with cancer is associated with a poor prognosis. Cancer patients are a vulnerable group, threatened by COVID-19, finding a way to combat COVID-19 for them is urgent. Immunonutrition is closely related to balance and strong immune function. Supplementary immunonutrition can improve the immune function and inflammatory response of cancer patients after surgery, which provides evidence for the role of immunonutrition in combating COVID-19. We reviewed possible mechanisms of immunonutrition against COVID-19, including enhancing immune cell function, increasing immune cell count, ameliorating excessive inflammatory response, and regulating gut microbiota. Immunonutrition supplementation in cancer patients may be beneficial to enhance immune function in the early stage of COVID-19 infection and control excessive inflammatory response in the late stage. Therefore, immunonutrition is a potential strategy for the prevention and treatment of COVID-19 in cancer.

The Nexus Between Telomere Length and Lymphocyte Count in Seniors Hospitalized With COVID-19

Profound T-cell lymphopenia is the hallmark of severe coronavirus disease 2019 (COVID-19). T-cell proliferation is telomere length (TL) dependent and telomeres shorten with age. Older COVID-19 patients, we hypothesize, are, therefore, at a higher risk of having TL-dependent lymphopenia. We measured TL by the novel Telomere Shortest Length Assay (TeSLA), and by Southern blotting (SB) of the terminal restriction fragments in peripheral blood mononuclear cells of 17 COVID-19 and 21 non-COVID-19 patients, aged 87 ± 8 (mean ± SD) and 87 ± 9 years, respectively. TeSLA tallies and measures single telomeres, including short telomeres undetected by SB. Such telomeres are relevant to TL-mediated biological processes, including cell viability and senescence. TeSLA yields 2 key metrics: the proportions of telomeres with different lengths (expressed in %) and their mean (TeSLA mTL), (expressed in kb). Lymphocyte count (109/L) was 0.91 ± 0.42 in COVID-19 patients and 1.50 ± 0.50 in non-COVID-19 patients (p < .001). In COVID-19 patients, but not in non-COVID-19 patients, lymphocyte count was inversely correlated with the proportion of telomeres shorter than 2 kb (p = .005) and positively correlated with TeSLA mTL (p = .03). Lymphocyte count was not significantly correlated with SB mTL in either COVID-19 or non-COVID-19 patients. We propose that compromised TL-dependent T-cell proliferative response, driven by short telomere in the TL distribution, contributes to COVID-19 lymphopenia among old adults. We infer that infection with SARS-CoV-2 uncovers the limits of the TL reserves of older persons. Clinical Trials Registration Number: NCT04325646.

Immune Signature Linked to COVID-19 Severity: A SARS-Score for Personalized Medicine

SARS-CoV-2 infection leads to a highly variable clinical evolution, ranging from asymptomatic to severe disease with acute respiratory distress syndrome, requiring intensive care units (ICU) admission. The optimal management of hospitalized patients has become a worldwide concern and identification of immune biomarkers predictive of the clinical outcome for hospitalized patients remains a major challenge. Immunophenotyping and transcriptomic analysis of hospitalized COVID-19 patients at admission allow identifying the two categories of patients. Inflammation, high neutrophil activation, dysfunctional monocytic response and a strongly impaired adaptive immune response was observed in patients who will experience the more severe form of the disease. This observation was validated in an independent cohort of patients. Using in silico analysis on drug signature database, we identify differential therapeutics that specifically correspond to each group of patients. From this signature, we propose a score-the SARS-Score-composed of easily quantifiable biomarkers, to classify hospitalized patients upon arrival to adapt treatment according to their immune profile.

Endothelial Senescence and Chronic Fatigue Syndrome, a COVID-19 Based Hypothesis

Myalgic encephalomyelitis/chronic fatigue syndrome is a serious illness of unknown etiology, characterized by debilitating exhaustion, memory impairment, pain and sleep abnormalities. Viral infections are believed to initiate the pathogenesis of this syndrome although the definite proof remains elusive. With the unfolding of COVID-19 pandemic, the interest in this condition has resurfaced as excessive tiredness, a major complaint of patients infected with the SARS-CoV-2 virus, often lingers for a long time, resulting in disability, and poor life quality. In a previous article, we hypothesized that COVID-19-upregulated angiotensin II triggered premature endothelial cell senescence, disrupting the intestinal and blood brain barriers. Here, we hypothesize further that post-viral sequelae, including myalgic encephalomyelitis/chronic fatigue syndrome, are promoted by the gut microbes or toxin translocation from the gastrointestinal tract into other tissues, including the brain. This model is supported by the SARS-CoV-2 interaction with host proteins and bacterial lipopolysaccharide. Conversely, targeting microbial translocation and cellular senescence may ameliorate the symptoms of this disabling illness.

SARS-CoV-2 exacerbates proinflammatory responses in myeloid cells through C-type lectin receptors and Tweety family member 2

Despite mounting evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) engagement with immune cells, most express little, if any, of the canonical receptor of SARS-CoV-2, angiotensin-converting enzyme 2 (ACE2). Here, using a myeloid cell receptor-focused ectopic expression screen, we identified several C-type lectins (DC-SIGN, L-SIGN, LSECtin, ASGR1, and CLEC10A) and Tweety family member 2 (TTYH2) as glycan-dependent binding partners of the SARS-CoV-2 spike. Except for TTYH2, these molecules primarily interacted with spike via regions outside of the receptor-binding domain. Single-cell RNA sequencing analysis of pulmonary cells from individuals with coronavirus disease 2019 (COVID-19) indicated predominant expression of these molecules on myeloid cells. Although these receptors do not support active replication of SARS-CoV-2, their engagement with the virus induced robust proinflammatory responses in myeloid cells that correlated with COVID-19 severity. We also generated a bispecific anti-spike nanobody that not only blocked ACE2-mediated infection but also the myeloid receptor-mediated proinflammatory responses. Our findings suggest that SARS-CoV-2-myeloid receptor interactions promote immune hyperactivation, which represents potential targets for COVID-19 therapy.

COVID-19 vaccines and nanomedicine

Background

The COVID‐19 virus‐induced pandemic has been the deadliest pandemic to have occurred in two generations, besides HIV/AIDS. Epidemiologists predicted that the SARS‐Cov 2 pandemic would not be able to be brought under control until a majority of the world’s population had been inoculated with safe and effective vaccines. A world‐wide effort to expedite vaccine development was successful. Previous research for vaccines to prevent SARS and MERS, also coronaviruses, was vital to this success. Nanotechnology was essential to this vaccine development. Key elements are presented here to better understand the relationship between nanomedicine and the COVID‐19 vaccine development.

Methods

NLM PubMed searches for COVID‐19 vaccines, nanotechnology and nanomedicine were done. There were 6911 articles screened, 235 of which were deemed appropriate to this subject and utilized here, together with two landmark nanomedicine texts used to expand understanding of the basic science of nanotechnology.

Results

SARS‐Cov 2, caused by the COVID‐19 virus, was first recognized in China in December of 2019 and was declared as a pandemic in March of 2020. The RNA sequence was identified in January of 2020. Within 4 months of the viral genome being released, over 259 vaccines had been in development. The World Health Organization (WHO) anticipated a vaccine with a 50‐80% efficacy to be developed within 1‐2 years. Ahead of schedule, the Food and Drug Administration (FDA) announced the emergency authorization approval for two mRNA vaccines within 11 month’s time. Nanotechnology was the key to the success of these rapidly developed, safe and effective vaccines. A brief review of pertinent basic science principles of nanomedicine are presented. The development of COVID vaccines is reviewed. Future considerations are discussed.

Conclusions

Control of the COVID‐19 SARS‐Cov2 pandemic benefitted from nanomedicine principles used to develop highly effective, yet very safe and relatively inexpensive vaccines. These nanovaccines can be much more easily altered to adjust for viral variants than traditional live or inactivated legacy‐type whole virus vaccines.

Hospital mortality in COVID-19 patients in Belgium treated with statins, ACE inhibitors and/or ARBs

The COVID-19 pandemic has disrupted life throughout the world. Newly developed vaccines promise relief to people who live in high-income countries, although vaccines and expensive new treatments are unlikely to arrive in time to help people who live in low-and middle-income countries. The pathogenesis of COVID-19 is characterized by endothelial dysfunction. Several widely available drugs like statins, ACE inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) have immunometabolic activities that (among other things) maintain or restore endothelial cell function. For this reason, we undertook an observational study in four Belgian hospitals to determine whether in-hospital treatment with these drugs could improve survival in 959 COVID-19 patients. We found that treatment with statins and ACEIs/ARBs reduced 28-day mortality in hospitalized COVID-19 patients. Moreover, combination treatment with these drugs resulted in a 3-fold reduction in the odds of hospital mortality (OR = 0.33; 95% CI 0.17–0.69). These findings were in general agreement with other published studies. Additional observational studies and clinical trials are needed to convincingly show that in-hospital treatment with statins, ACEIs/ARBs, and especially their combination saves lives.

COVID-19-associated Aspergillus tracheobronchitis: the interplay between viral tropism, host defence, and fungal invasion

Invasive pulmonary aspergillosis is emerging as a secondary infection in patients with COVID-19, which can present as alveolar disease, airway disease (ie, invasive Aspergillus tracheobronchitis), or both. Histopathology of invasive Aspergillus tracheobronchitis in patients with severe COVID-19 confirms tracheal ulcers with tissue invasion of Aspergillus hyphae but without angioinvasion, which differs from patients with severe influenza, where early angioinvasion is observed. We argue that aggregation of predisposing factors (eg, factors that are defined by the European Organisation for Research and Treatment of Cancer and Mycoses Study Group Education and Research Consortium or genetic polymorphisms), viral factors (eg, tropism and lytic effects), immune defence factors, and effects of concomitant therapies will determine whether and when the angioinvasion threshold is reached. Management of invasive Aspergillus tracheobronchitis should include reducing viral lytic effects, rebalancing immune dysregulation, and systemic and local antifungal therapy. Future study designs should involve approaches that aim to develop improved diagnostics for tissue invasion and airways involvement and identify the immune status of the patient to guide personalised immunotherapy.

2019 Coronavirus disease (COVID-19): contribution of rheumatology

The 2019 coronavirus disease (COVID-19) pandemic become a major challenge for humanity and a unique opportunity to get an idea of the real achievements of modern biology and medicine. In the course of the pandemic, a large number of new fundamental and medical issues have been revealed regarding the relationship between viral infection and many common chronic non-infectious diseases, among which immune-mediated rheumatic diseases (IMRD) occupy an important position. It is now well known that SARS-CoV-2 infection is accompanied by a wide range of extrapulmonary clinical and laboratory disorders, some of which are characteristic of IMRD and other autoimmune and autoinflammatory diseases in humans. The most severe consequence of alterations in regulation of the immunity in COVID-19 and IMRD is the so-called cytokine storm syndrome, which is defined as COVID-19-associated hyperinflammatory syndrome in COVID-19, and as macrophage activation syndrome in IMRD. The COVID-19-associated hyperinflammatory syndrome was used as a reason for drug repurposing and off-label use of a wide range of anti-inflammatory drugs, which have been specially developed for the treatment of IMRD over the past 20 years. Common immunopathological mechanisms and approaches to pharmacotherapy in COVID-19 and IMRD determined the unique place of rheumatology among medical specialties contributing to combat the COVID-19 pandemic. The article provides the basic provisions of the International and National Association of Rheumatologists and the Association of Rheumatologists of Russia (ARR) recommendations for management of patients with IMRD during the COVID-19 pandemic.

Increased complement activation is a distinctive feature of severe SARS-CoV-2 infection

Complement activation has been implicated in the pathogenesis of severe SARS-CoV-2 infection. However, it remains to be determined whether increased complement activation is a broad indicator of critical illness (and thus, no different in COVID-19). It is also unclear which pathways are contributing to complement activation in COVID-19, and if complement activation is associated with certain features of severe SARS-CoV-2 infection, such as endothelial injury and hypercoagulability. To address these questions, we investigated complement activation in the plasma from patients with COVID-19 prospectively enrolled at two tertiary care centers: Washington University School of Medicine (n=134) and Yale School of Medicine (n=49). We compared our patients to two non-COVID cohorts: (a) patients hospitalized with influenza (n=54), and (b) patients admitted to the intensive care unit (ICU) with acute respiratory failure requiring invasive mechanical ventilation (IMV, n=22). We demonstrate that circulating markers of complement activation are elevated in patients with COVID-19 compared to those with influenza and to patients with non-COVID-19 respiratory failure. Further, the results facilitate distinguishing those who are at higher risk of worse outcomes such as requiring ICU admission, or IMV. Moreover, the results indicate enhanced activation of the alternative complement pathway is most prevalent in patients with severe COVID-19 and is associated with markers of endothelial injury (i.e., angiopoietin-2) as well as hypercoagulability (i.e., thrombomodulin and von Willebrand factor). Our findings identify complement activation to be a distinctive feature of COVID-19, and provide specific targets that may be utilized for risk prognostication, drug discovery and personalized clinical trials.

Acute and chronic exposure to air pollution in relation with incidence, prevalence, severity and mortality of COVID-19: a rapid systematic review

BACKGROUND

Air pollution is one of the world's leading mortality risk factors contributing to seven million deaths annually. COVID-19 pandemic has claimed about one million deaths in less than a year. However, it is unclear whether exposure to acute and chronic air pollution influences the COVID-19 epidemiologic curve.

METHODS

We searched for relevant studies listed in six electronic databases between December 2019 and September 2020. We applied no language or publication status limits. Studies presented as original articles, studies that assessed risk, incidence, prevalence, or lethality of COVID-19 in relation with exposure to either short-term or long-term exposure to ambient air pollution were included. All patients regardless of age, sex and location diagnosed as having COVID-19 of any severity were taken into consideration. We synthesised results using harvest plots based on effect direction.

RESULTS

Included studies were cross-sectional (n = 10), retrospective cohorts (n = 9), ecological (n = 6 of which two were time-series) and hypothesis (n = 1). Of these studies, 52 and 48% assessed the effect of short-term and long-term pollutant exposure, respectively and one evaluated both. Pollutants mostly studied were PM2.5 (64%), NO2 (50%), PM10 (43%) and O3 (29%) for acute effects and PM2.5 (85%), NO2 (39%) and O3 (23%) then PM10 (15%) for chronic effects. Most assessed COVID-19 outcomes were incidence and mortality rate. Acutely, pollutants independently associated with COVID-19 incidence and mortality were first PM2.5 then PM10, NO2 and O3 (only for incident cases). Chronically, similar relationships were found for PM2.5 and NO2. High overall risk of bias judgments (86 and 39% in short-term and long-term exposure studies, respectively) was predominantly due to a failure to adjust aggregated data for important confounders, and to a lesser extent because of a lack of comparative analysis.

CONCLUSION

The body of evidence indicates that both acute and chronic exposure to air pollution can affect COVID-19 epidemiology. The evidence is unclear for acute exposure due to a higher level of bias in existing studies as compared to moderate evidence with chronic exposure. Public health interventions that help minimize anthropogenic pollutant source and socio-economic injustice/disparities may reduce the planetary threat posed by both COVID-19 and air pollution pandemics.

Coronavirus disease 2019 (COVID-19) and autoimmunity

The coronavirus 2019 pandemic (coronavirus disease, COVID-19), etiologically related to the SARS-CoV-2 virus (severe acute respiratory syndrome coronavirus-2), has once again reawakened healthcare professionals’ interest towards new clinical and conceptual issues of human immunology and immunopathology. An unprecedented number of clinical trials and fundamental studies of epidemiology, virology, immunology and molecular biology, of the COVID-19 clinical course polymorphism and pharmacotherapy have been conducted within one year since the outbreak of 2019 pandemic, bringing together scientists of almost all biological and physicians of almost all medical specialties. Their joint efforts have resulted in elaboration of several types of vaccines against SARS-CoV-2 infection and, in general, fashioning of more rational approaches to patient management. Also important for COVID-19 management were all clinical trials of biologics and “targeted” anti-inflammatory drugs modulating intracellular cytokine signaling, which have been specifically developed for treatment immune-mediated inflammatory rheumatic disease (IMIRDs) over the past 20 years. It became obvious after a comprehensive analysis of the entire spectrum of clinical manifestations and immunopathological disorders in COVID-19 is accompanied by a wide range of extrapulmonary clinical and laboratory disorders, some of which are characteristic of IMIRDs and other autoimmune and auto-in-flammatory human diseases. All these phenomena substantiated the practice of anti-inflammatory drugs repurposing with off-label use of specific antirheumatic agents for treatment of COVID-19. This paper discusses potential use of glucocorticoids, biologics, JAK inhibitors, etc., blocking the effects of pro-inflammatory cytokines for treatment of COVID-19.

Lymphocyte subsets early predict mortality in a large series of hospitalized COVID-19 patients in Spain

The role of lymphocytes and their main subsets as prognostic factors of death in SARS-CoV-2-infected patients remains unclear, with no information obtained from patients outside China. We aimed to assess whether measuring lymphocyte subpopulations added clinical value to the total lymphocyte counting regarding mortality when they were simultaneously tested at hospital admission. Peripheral blood was analysed in 701 polymerase chain reaction (PCR)-confirmed consecutive patients by lysed-no washed flow cytometry. Demographic and clinical features were registered in electronic medical records. Statistical analysis was performed after a 3-month follow-up. The 112 patients who died were older and had significantly higher frequencies of known co-morbidities than survivor COVID-19 patients. A significant reduction in total lymphocytes, CD3+ , CD4+ , CD8+ and CD19+ counts and CD3+ percentage was found in the group of deceased patients (P < 0·001), while the percentage of CD56+ /CD16+ natural killer (NK) cells was significantly higher (P < 0·001). Multivariate logistic regression analysis showed a significantly increased risk of in-hospital death associated to age [odds ratio (OR) = 2·36, 95% confidence interval (CI) = 1·9-3·0 P < 0·001]; CD4+  T counts ≤ 500 cells/μl, (OR = 2·79, 95% CI = 1·1-6·7, P = 0·021); CD8+  T counts ≤ 100 cells/μl, (OR = 1·98, 95% CI = 1·2-3·3) P = 0·009) and CD56+ /CD16+ NK ≥ 30%, (OR = 1·97, 95% CI = 1·1-3·1, P = 0·002) at admission, independent of total lymphocyte numbers and co-morbidities, with area under the curve 0·85 (95% CI = 0·81-0·88). Reduced counts of CD4+ and CD8+ T cells with proportional expansion of NK lymphocytes at admission were prognostic factors of death in this Spanish series. In COVID-19 patients with normal levels of lymphocytes or mild lymphopenia, imbalanced lymphocyte subpopulations were early markers of in-hospital mortality.

Increased complement activation is a distinctive feature of severe SARS-CoV-2 infection

Complement activation has been implicated in the pathogenesis of severe SARS-CoV-2 infection. However, it remains to be determined whether increased complement activation is a broad indicator of critical illness (and thus, no different in COVID-19). It is also unclear which pathways are contributing to complement activation in COVID-19, and, if complement activation is associated with certain features of severe SARS-CoV-2 infection, such as endothelial injury and hypercoagulability. To address these questions, we investigated complement activation in the plasma from patients with COVID-19 prospectively enrolled at two tertiary care centers. We compared our patients to two non-COVID cohorts: (a) patients hospitalized with influenza, and (b) patients admitted to the intensive care unit (ICU) with acute respiratory failure requiring invasive mechanical ventilation (IMV). We demonstrate that circulating markers of complement activation (i.e., sC5b-9) are elevated in patients with COVID-19 compared to those with influenza and to patients with non-COVID-19 respiratory failure. Further, the results facilitate distinguishing those who are at higher risk of worse outcomes such as requiring ICU admission, or IMV. Moreover, the results indicate enhanced activation of the alternative complement pathway is most prevalent in patients with severe COVID-19 and is associated with markers of endothelial injury (i.e., Ang2) as well as hypercoagulability (i.e., thrombomodulin and von Willebrand factor). Our findings identify complement activation to be a distinctive feature of COVID-19, and provide specific targets that may be utilized for risk prognostication, drug discovery and personalized clinical trials.

Interferons and other cytokines, genetics and beyond in COVID-19 and autoimmunity

Interferons are the best antiviral agents in vitro against SARS-CoV-2 so far and genetic defects in their signaling cascade or neutralization of alfa-interferons by autoantibodies come with more severe COVID-19. However, there is more, as the SARS-CoV-2 dysregulates not only innate immune mechanisms but also T and B cell repertoires. Most genetic, hematological and immunological studies in COVID-19 are at present phenomenological. However, these and antecedent studies contain the seed grains to resolve many unanswered questions and a whole range of testable hypotheses. What are the links, if existing, between genetics and the occurrence of interferon-neutralizing antibodies? Are NAGGED (neutralizing and generated by gene defect) antibodies involved or not? Is the autoimmune process cause or consequence of virus infection? What are the roles played by cytokine posttranslational modifications, such as proteolysis, glycosylation, citrullination and others? How is systemic autoimmunity linked with type 1 interferons? These questions place cytokines and growth factors at pole positions as keys to unlock basic mechanisms of infection and (auto)immunity. Related to cytokine research, (1) COVID-19 patients develop neutralizing autoantibodies, mainly against alpha interferons and it is not yet established whether this is the consequence or cause of virus replication. (2) The glycosylation of recombinant interferon-beta protects against breaking tolerance and the development of neutralizing antibodies. (3) SARS-CoV-2 induces severe inflammation and release of extracellular proteases leading to remnant epitopes, e.g. of cytokines. (4) In the rare event of homozygous cytokine gene segment deletions, observed neutralizing antibodies may be named NAGGED antibodies. (5) Severe cytolysis releases intracellular content into the extracellular milieu and leads to regulated degradation of intracellular proteins and selection of antibody repertoires, similar to those observed in patients with systemic lupus erythematosus. (6) Systematic studies of novel autoimmune diseases on single cytokines will complement the present picture about interferons. (7) Interferon neutralization in COVID-19 constitutes a preamble of more studies about cytokine-regulated proteolysis in the control of autoimmunity. Here we reformulate these seven conjectures into testable questions for future research.

High-dimensional single-cell analysis reveals the immune characteristics of COVID-19

Coronavirus disease 2019 (COVID-19), driven by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was declared a global pandemic in March 2020. Pathogenic T cells and inflammatory monocytes are regarded as the central drivers of the cytokine storm associated with the severity of COVID-19. In this study, we explored the characteristic peripheral cellular profiles of patients with COVID-19 in both acute and convalescent phases by single-cell mass cytometry (CyTOF). Using a combination of algorithm-guided data analyses, we identified peripheral immune cell subsets in COVID-19 and revealed CD4+ T-cell depletion, T-cell differentiation, plasma cell expansion, and the reduced antigen presentation capacity of innate immunity. Notably, COVID-19 induces a dysregulation in the balance of monocyte populations by the expansion of the monocyte subsets. Collectively, our results represent a high-dimensional, single-cell profile of the peripheral immune response to SARS-CoV-2 infection.

Covid-19-Associated Pulmonary Aspergillosis: The Other Side of the Coin

The immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a critical factor in the clinical presentation of COVID-19, which may range from asymptomatic to a fatal, multi-organ disease. A dysregulated immune response not only compromises the ability of the host to resolve the viral infection, but may also predispose the individual to secondary bacterial and fungal infections, a risk to which the current therapeutic immunomodulatory approaches significantly contribute. Among the secondary infections that may occur in COVID-19 patients, coronavirus-associated pulmonary aspergillosis (CAPA) is emerging as a potential cause of morbidity and mortality, although many aspects of the disease still remain unresolved. With this opinion, we present the current view of CAPA and discuss how the same mechanisms that underlie the dysregulated immune response in COVID-19 increase susceptibility to Aspergillus infection. Likewise, resorting to endogenous pathways of immunomodulation may not only restore immune homeostasis in COVID-19 patients, but also reduce the risk for aspergillosis. Therefore, CAPA represents the other side of the coin in COVID-19 and our advances in the understanding and treatment of the immune response in COVID-19 should represent the framework for the study of CAPA.