Vascular Disease and Thrombosis in SARS-CoV-2-Infected Rhesus Macaques

Extraction of naturally occurring peptides versus the tryptic digestion of proteins from fetal versus adult bovine serum for LC-ESI-MS/MS

The naturally occurring peptides and digested proteins of fetal versus adult bovine serum were compared by LC-ESI-MS/MS after correction against noise from blank injections and random MS/MS spectra as statistical controls. Serum peptides were extracted by differential precipitation with mixtures of acetonitrile and water. Serum proteins were separated by partition chromatography over quaternary amine resin followed by tryptic digestion. The rigorous X!TANDEM goodness of fit algorithm that has a low error rate as demonstrated by low FDR q-values (q ≤ 0.01) showed qualitative and quantitative agreement with the SEQUEST cross correlation algorithm on 12,052 protein gene symbols. Tryptic digestion provided a quantitative identification of the serum proteins where observation frequency reflected known high abundance. In contrast, the naturally occurring peptides reflected the cleavage of common serum proteins such as C4A, C3, FGB, HPX, A2M but also proteins in lower concentration such as F13A1, IK, collagens and protocadherins. Proteins associated with cellular growth and development such as actins (ACT), ribosomal proteins like Ribosomal protein S6 (RPS6), synthetic enzymes and extracellular matrix factors were enriched in fetal calf serum. In contrast to the large literature from cord blood, IgG light chains were absent from fetal serum as observed by LC-ESI-MS/MS and confirmed by ELISA.

The regulation of cGAS-STING signaling by RNA virus-derived components

The Cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) serves as a key innate immune signaling axis involved in the regulation of various human diseases. It has been found that cGAS-STING pathway can recognize a variety of cytosolic double-stranded DNA (dsDNA), contributing to cause a robust type I interferon response thereby affecting the occurrence and progression of viral infection. Accumulating evidence indicates RNA virus-derived components play an important role in regulating cGAS-STING signaling, either as protective or pathogenic factors in the pathogenesis of diseases. Thus, a comprehensive understanding of the function of RNA virus-derived components in regulating cGAS-STING signaling will provide insights into developing novel therapies. Here, we review the existing literature on cGAS-STING pathway regulated by RNA virus-derived components to propose insights into pharmacologic strategies targeting the cGAS-STING pathway.

Role of the RAAS in mediating the pathophysiology of COVID-19

The renin-angiotensin-aldosterone system (RAAS) holds a position of paramount importance as enzymatic and endocrine homeostatic regulator concerning the water-electrolyte and acid-base balance. Nevertheless, its intricacy is influenced by the presence of various complementary angiotensins and their specific receptors, thereby modifying the primary RAAS actions. Angiotensin-converting enzyme 2 (ACE2) acts as a surface receptor for SARS-CoV-2, establishing an essential connection between RAAS and COVID-19 infection. Despite the recurring exploration of the RAAS impact on the trajectory of COVID-19 along with the successful resolution of many inquiries, its complete role in the genesis of delayed consequences encompassing long COVID and cardiovascular thrombotic outcomes during the post-COVID phase as well as post-vaccination, remains not fully comprehended. Particularly noteworthy is the involvement of the RAAS in the molecular mechanisms underpinning procoagulant processes throughout COVID-19. These processes significantly contribute to the pathogenesis of organ complications as well as determine clinical outcomes and are discussed in this manuscript.

Interferons prime the endothelium for toll-like receptor-mediated thrombin generation

BACKGROUND

Respiratory infection is associated with microvascular thrombus formation and marked elevation in cytokine levels. The role of cytokines elaborated by the pulmonary epithelium in thrombotic responses is poorly understood.

OBJECTIVES

Our goal was to identify cytokines of pulmonary epithelial cell origin that enhance thrombin generation in the endothelium at concentrations equal to or less than those found in the circulation during infection.

METHODS

We screened multiple cytokines produced by the pulmonary epithelium for the ability to enhance toll-like receptor (TLR)-mediated endothelial thrombin generation. Effects of cytokines on tissue factor and thrombomodulin expression, cytokine selectivity for different TLRs, and prothrombotic activity of endogenous cytokines in conditioned medium from pulmonary human epithelial cells were evaluated.

RESULTS

MIP-1β, MCP-1, IL-10, IL-6, IL-1β, TNFα, IFNα, IFNβ, and IFNγ were tested for their ability to enhance TLR3-mediated thrombin generation on endothelial cells. Only interferons (IFNs) and TNFα promoted TLR3-mediated thrombin generation at levels that circulate during infection. IFNs robustly enhanced tissue factor expression when used in conjunction with TLR agonists and reduced thrombomodulin expression in the endothelium independently of TLRs. IFNα, which is typically elevated with viral infection, only synergized with TLR3 agonists mimicking viral pathogen-associated molecular patterns. In contrast, IFNγ, which is typically observed in bacterial infection, synergized more effectively with TLR4 agonists released by bacteria. Conditioned media from inflamed pulmonary epithelial cells primed the endothelium for TLR-mediated thrombin generation. Anti-IFN type I antibodies blocked this effect, indicating that endogenous IFNs prime the endothelium for TLR-mediated thrombin generation.

CONCLUSION

IFNs elaborated by the pulmonary epithelium are necessary and sufficient to enhance TLR-mediated thrombin generation.

Dual-targeting fucoidan-based microvesicle for arterial thrombolysis and re-occlusion inhibition

Arterial thrombosis is a critical thrombotic disease that poses a significant threat to human health. However, the existing clinical treatment of arterial thrombosis lacks effective targeting and precise drug release capability. In this study, we developed a system for targeted delivery and on-demand release in arterial thrombosis treatment. The carrier was constructed using chitosan (CS) and fucoidan (Fu) through layer-by-layer assembly, with subsequent surface modification using cRGD peptide. Upon encapsulation of urokinase-type plasminogen activator (uPA), the resulting therapeutic drug delivery system, uPA-CS/Fu@cRGD, demonstrated dual-targeting abilities towards P-selectin and αIIbβ3, as well as pH and platelet-responsive release properties. Importantly, we have demonstrated that the dual targeting effect exhibits higher targeting efficiency at shear rates simulating thrombosed arterial conditions (1800 s-1) compared to single targeting for the first time. In the mouse common iliac artery model, uPA-CS/Fu@cRGD exhibited great thrombolytic capability while promoting the down-regulation of coagulation factors (FXa and PAI-1) and inflammatory factors (TNF-α and IL-6), thus improving the thrombus microenvironment and exerting potential in preventing re-occlusion. Our dual-target and dual-responsive, fucoidan-based macrovesicle represent a promising platform for advanced drug target delivery applications, with potential to prevent coagulation tendencies as well as improving thrombolytic and reducing the risk of re-occlusion.

Coagulation profile in hospitalized children with COVID-19: pediatric age dependency and its impact on long COVID development

Introduction

Pulmonary endotheliopathy and microvascular immunothrombosis play a key role in acute COVID-19. Moreover, persistent endotheliopathy and heightened coagulability frequently occur in individuals recovering from COVID-19, suggesting the intriguing possibility of their role in the development of long COVID. The aim of our study was to investigate the coagulation profile in patients with COVID-19 based on age and their role in the development of long COVID.

Methods

We conducted a prospective single-center cohort study from September 2022 to August 2023. The study involved 190 patients younger than 18 years who were hospitalized at the Ternopil City Children's Hospital, Ukraine due to COVID-19. Patients underwent determination of coagulation profile in addition to the general clinical examination. After discharge from the hospital, patients were monitored for the presence of long COVID symptoms. Among the 157 participants who consented for follow-up, 62 patients (39.5%) had long COVID symptoms according to the WHO definition, while the rest (95 patients) did not have symptoms of long COVID (fully recovered).

Results

The study revealed the normal count of platelets in the majority of patients (86.8%), whereas abnormalities in the coagulation profile were revealed in 94.5% of children with COVID-19, and these changes were age-dependent. The patients were mostly presented with increased activated partial thromboplastin time (69.1%), prothrombin time (PT) (39.8%) and D-dimer (45.0%). There was no significant difference between the median of platelet levels and coagulation profile indicators between the groups with long COVID and recovered. Among children who developed persistent long COVID symptoms there was a statistically higher percentage of abnormal PT values (53% versus 36.1%, p=0.0432), with no significant differences in other coagulation profile indicators. Abnormal PT along with female gender, comorbidities, especially allergic pathology, nutritional disorder, including obesity, were determined as potential risk factors of the long COVID development (Odds ratio - 2.0611; 95% 1.0179-4.1737, p=0.0445).

Conclusions

The study highlights the need for more extensive research into the coagulation profiles of pediatric populations, considering age-specific factors. This could enhance our understanding of thromboinflammation in COVID-19 and its potential contribution to the development of persistent symptoms.

Systems immunology of transcriptional responses to viral infection identifies conserved antiviral pathways across macaques and humans

Viral pandemics and epidemics pose a significant global threat. While macaque models of viral disease are routinely used, it remains unclear how conserved antiviral responses are between macaques and humans. Therefore, we conducted a cross-species analysis of transcriptomic data from over 6,088 blood samples from macaques and humans infected with one of 31 viruses. Our findings demonstrate that irrespective of primate or viral species, there are conserved antiviral responses that are consistent across infection phase (acute, chronic, or latent) and viral genome type (DNA or RNA viruses). Leveraging longitudinal data from experimental challenges, we identify virus-specific response kinetics such as host responses to Coronaviridae and Orthomyxoviridae infections peaking 1-3 days earlier than responses to Filoviridae and Arenaviridae viral infections. Our results underscore macaque studies as a powerful tool for understanding viral pathogenesis and immune responses that translate to humans, with implications for viral therapeutic development and pandemic preparedness.

SARS-CoV-2 immunity in animal models

The COVID-19 pandemic, which was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a worldwide health crisis due to its transmissibility. SARS-CoV-2 infection results in severe respiratory illness and can lead to significant complications in affected individuals. These complications encompass symptoms such as coughing, respiratory distress, fever, infectious shock, acute respiratory distress syndrome (ARDS), and even multiple-organ failure. Animal models serve as crucial tools for investigating pathogenic mechanisms, immune responses, immune escape mechanisms, antiviral drug development, and vaccines against SARS-CoV-2. Currently, various animal models for SARS-CoV-2 infection, such as nonhuman primates (NHPs), ferrets, hamsters, and many different mouse models, have been developed. Each model possesses distinctive features and applications. In this review, we elucidate the immune response elicited by SARS-CoV-2 infection in patients and provide an overview of the characteristics of various animal models mainly used for SARS-CoV-2 infection, as well as the corresponding immune responses and applications of these models. A comparative analysis of transcriptomic alterations in the lungs from different animal models revealed that the K18-hACE2 and mouse-adapted virus mouse models exhibited the highest similarity with the deceased COVID-19 patients. Finally, we highlighted the current gaps in related research between animal model studies and clinical investigations, underscoring lingering scientific questions that demand further clarification.

Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles

The SARS-CoV-2 pandemic not only resulted in millions of acute infections worldwide, but also in many cases of post-infectious syndromes, colloquially referred to as "long COVID". Due to the heterogeneous nature of symptoms and scarcity of available tissue samples, little is known about the underlying mechanisms. We present an in-depth analysis of skeletal muscle biopsies obtained from eleven patients suffering from enduring fatigue and post-exertional malaise after an infection with SARS-CoV-2. Compared to two independent historical control cohorts, patients with post-COVID exertion intolerance had fewer capillaries, thicker capillary basement membranes and increased numbers of CD169+ macrophages. SARS-CoV-2 RNA could not be detected in the muscle tissues. In addition, complement system related proteins were more abundant in the serum of patients with PCS, matching observations on the transcriptomic level in the muscle tissue. We hypothesize that the initial viral infection may have caused immune-mediated structural changes of the microvasculature, potentially explaining the exercise-dependent fatigue and muscle pain.

Pathogenesis of severe acute respiratory syndrome coronavirus-2 in nonhuman primates

The continued pressure of COVID-19 on public health worldwide underlines the need for a better understanding of the mechanisms of disease caused by severe acute respiratory syndrome coronavirus-2. Though many animal models are readily available for use, the nonhuman primate (NHP) models are considered the gold standard in recapitulating disease progression in humans. In this review, we highlight the relevant research since the beginning of the pandemic to critically evaluate the importance of this model. We characterize the disease's clinical manifestations, aspects of viral replication and shedding, induction of the host's immune response, and pathological findings that broaden our understanding of the importance of NHPs in research to strengthen our public health approach to the pandemic.

Aerosol delivery of SARS-CoV-2 human monoclonal antibodies in macaques limits viral replication and lung pathology

Passively administered monoclonal antibodies (mAbs) given before or after viral infection can prevent or blunt disease. Here, we examine the efficacy of aerosol mAb delivery to prevent infection and disease in rhesus macaques inoculated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant via intranasal and intratracheal routes. SARS-CoV-2 human mAbs or a human mAb directed to respiratory syncytial virus (RSV) are nebulized and delivered using positive airflow via facemask to sedated macaques pre- and post-infection. Nebulized human mAbs are detectable in nasal, oropharyngeal, and bronchoalveolar lavage (BAL) samples. SARS-CoV-2 mAb treatment significantly reduces levels of SARS-CoV-2 viral RNA and infectious virus in the upper and lower respiratory tracts relative to controls. Reductions in lung and BAL virus levels correspond to reduced BAL inflammatory cytokines and lung pathology. Aerosolized antibody therapy for SARS-CoV-2 could be effective for reducing viral burden and limiting disease severity.

Complement factor D targeting protects endotheliopathy in organoid and monkey models of COVID-19

COVID-19 is linked to endotheliopathy and coagulopathy, which can result in multi-organ failure. The mechanisms causing endothelial damage due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain elusive. Here, we developed an infection-competent human vascular organoid from pluripotent stem cells for modeling endotheliopathy. Longitudinal serum proteome analysis identified aberrant complement signature in critically ill patients driven by the amplification cycle regulated by complement factor B and D (CFD). This deviant complement pattern initiates endothelial damage, neutrophil activation, and thrombosis specific to organoid-derived human blood vessels, as verified through intravital imaging. We examined a new long-acting, pH-sensitive (acid-switched) antibody targeting CFD. In both human and macaque COVID-19 models, this long-acting anti-CFD monoclonal antibody mitigated abnormal complement activation, protected endothelial cells, and curtailed the innate immune response post-viral exposure. Collectively, our findings suggest that the complement alternative pathway exacerbates endothelial injury and inflammation. This underscores the potential of CFD-targeted therapeutics against severe viral-induced inflammathrombotic outcomes.

Fishing for "complements" with vascular organoid models of microvascular disease

In this issue of Cell Stem Cell, Kawakami et al. develop a SARS-CoV-2 infection-competent, progenitor-derived, human vascular organoid model and uncover a role for complement factor D (CFD) in mediating microvascular immunothrombosis. This model may be applied to conditions where microvascular disease plays a major pathogenic role.

Impact of Environmental Factors on Hypertension and Associated Cardiovascular Disease

Hypertension is the primary cause of cardiovascular diseases and is responsible for nearly 9 million deaths worldwide annually. Increasing evidence indicates that in addition to pathophysiologic processes, numerous environmental factors, such as geographic location, lifestyle choices, socioeconomic status, and cultural practices, influence the risk, progression, and severity of hypertension, even in the absence of genetic risk factors. In this review, we discuss the impact of some environmental determinants on hypertension. We focus on clinical data from large population studies and discuss some potential molecular and cellular mechanisms. We highlight how these environmental determinants are interconnected, as small changes in one factor might affect others, and further affect cardiovascular health. In addition, we discuss the crucial impact of socioeconomic factors and how these determinants influence diverse communities with economic disparities. Finally, we address opportunities and challenges for new research to address gaps in knowledge on understanding molecular mechanisms whereby environmental factors influence development of hypertension and associated cardiovascular disease.

Thrombotic complications in children with Coronavirus disease 2019 and Multisystem Inflammatory Syndrome of Childhood

Coronavirus disease 2019 (COVID-19) associated coagulopathy is multifactorial and involves inflammation driven hypercoagulability, endothelial dysfunction, platelet activation, and impaired fibrinolysis. Hospitalized adults with COVID-19 are at an increased risk of both venous thromboembolism and ischemic stroke, resulting in adverse outcomes, including increased mortality. Although COVID-19 in children follows a less severe course, both arterial and venous thromboses have been reported in hospitalized children with COVID-19. Additionally, some children develop a postinfectious, hyperinflammatory illness termed multisystem inflammatory syndrome of childhood (MIS-C), which is also associated with hypercoagulability and thrombosis. Several randomized trials have evaluated the safety and efficacy of antithrombotic therapy in adults with COVID-19, although similar pediatric data are lacking. In this narrative review, we discuss the postulated pathophysiology of COVID-19 coagulopathy and summarize principal findings of the recently completed adult trials of antithrombotic therapy. We provide an up-to-date summary of pediatric studies investigating the rate of venous thromboembolism and ischemic stroke in COVID-19 and multisystem inflammatory syndrome of childhood in addition to reviewing the findings of the single, nonrandomized pediatric trial investigating the safety of prophylactic anticoagulation. Lastly, we outline adult and pediatric consensus guidelines on the use of antithrombotic therapy in this cohort. A detailed discussion of the practical implementation and current limitations of published data will hopefully address the knowledge deficits surrounding the use of antithrombotic therapy in children with COVID-19 and generate hypotheses for future research.

Spatial transcriptome atlas reveals pulmonary microstructure-specific COVID-19 gene signatures in cynomolgus macaques

Characterizing the host response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the molecular level is necessary to understand viral pathogenesis and identify clinically relevant biomarkers. However, in humans, the pulmonary host response during disease onset remains poorly understood. Herein, we utilized a spatial transcriptome atlas to identify pulmonary microstructure-specific COVID-19 gene signatures during the acute phase of lung infection in cynomolgus macaques. The innate immune response to virus-induced cell death was primarily active in the alveolar regions involving activated macrophage infiltration. Inflamed vascular regions exhibited prominent upregulation of interferon and complement pathway genes that mediate antiviral activity and tissue damage response. Furthermore, known biomarker genes were significantly expressed in specific microstructures, and some of them were universally expressed across all microstructures. These findings underscore the importance of identifying key drivers of disease progression and clinically applicable biomarkers by focusing on pulmonary microstructures appearing during SARS-CoV-2 infection.

Endothelial Damage, Neutrophil Extracellular Traps and Platelet Activation in COVID-19 vs. Community-Acquired Pneumonia: A Case-Control Study

COVID-19 has been a diagnostic and therapeutic challenge. It has marked a paradigm shift when considering other types of pneumonia etiology. We analyzed the biomarkers related to endothelial damage and immunothrombosis in COVID-19 in comparison to community-acquired pneumonia (CAP) through a case-control study of 358 patients with pneumonia (179 hospitalized with COVID-19 vs. 179 matched hospitalized with CAP). Endothelial damage markers (endothelin and proadrenomedullin), neutrophil extracellular traps (NETs) (citrullinated-3 histone, cell-free DNA), and platelet activation (soluble P-selectin) were measured. In-hospital and 1-year follow-up outcomes were evaluated. Endothelial damage, platelet activation, and NET biomarkers are significantly higher in CAP compared to COVID-19. In-hospital mortality in COVID-19 was higher compared to CAP whereas 1-year mortality and cardiovascular complications were higher in CAP. In the univariate analysis (OR 95% CIs), proADM and endothelin were associated with in-hospital mortality (proADM: CAP 3.210 [1.698-6.070], COVID-19 8.977 [3.413-23.609]; endothelin: CAP 1.014 [1.006-1.022], COVID-19 1.024 [1.014-1.034]), in-hospital CVE (proADM: CAP 1.623 [1.080-2.439], COVID-19 2.146 [1.186-3.882]; endothelin: CAP 1.005 [1.000-1.010], COVID-19 1.010 [1.003-1.018]), and 1-year mortality (proADM: CAP 2.590 [1.644-4.080], COVID-19 13.562 [4.872-37.751]; endothelin: CAP 1.008 [1.003-1.013], COVID-19 1.026 [1.016-1.037]). In conclusion, COVID-19 and CAP showed different expressions of endothelial damage and NETs. ProADM and endothelin are associated with short- and long-term mortality.

Animal models for COVID-19 and tuberculosis

Respiratory infections cause tremendous morbidity and mortality worldwide. Amongst these diseases, tuberculosis (TB), a bacterial illness caused by Mycobacterium tuberculosis which often affects the lung, and coronavirus disease 2019 (COVID-19) caused by the Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2), stand out as major drivers of epidemics of global concern. Despite their unrelated etiology and distinct pathology, these infections affect the same vital organ and share immunopathogenesis traits and an imperative demand to model the diseases at their various progression stages and localizations. Due to the clinical spectrum and heterogeneity of both diseases experimental infections were pursued in a variety of animal models. We summarize mammalian models employed in TB and COVID-19 experimental investigations, highlighting the diversity of rodent models and species peculiarities for each infection. We discuss the utility of non-human primates for translational research and emphasize on the benefits of non-conventional experimental models such as livestock. We epitomize advances facilitated by animal models with regard to understanding disease pathophysiology and immune responses. Finally, we highlight research areas necessitating optimized models and advocate that research of pulmonary infectious diseases could benefit from cross-fertilization between studies of apparently unrelated diseases, such as TB and COVID-19.

Modulation of type I interferon responses potently inhibits SARS-CoV-2 replication and inflammation in rhesus macaques

Type I interferons (IFN-I) are critical mediators of innate control of viral infections but also drive the recruitment of inflammatory cells to sites of infection, a key feature of severe coronavirus disease 2019. Here, IFN-I signaling was modulated in rhesus macaques (RMs) before and during acute SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection using a mutated IFN-α2 (IFN-modulator; IFNmod), which has previously been shown to reduce the binding and signaling of endogenous IFN-I. IFNmod treatment in uninfected RMs was observed to induce a modest up-regulation of only antiviral IFN-stimulated genes (ISGs); however, in SARS-CoV-2-infected RMs, IFNmod reduced both antiviral and inflammatory ISGs. IFNmod treatment resulted in a potent reduction in SARS-CoV-2 viral loads both in vitro in Calu-3 cells and in vivo in bronchoalveolar lavage (BAL), upper airways, lung, and hilar lymph nodes of RMs. Furthermore, in SARS-CoV-2-infected RMs, IFNmod treatment potently reduced inflammatory cytokines, chemokines, and CD163+ MRC1- inflammatory macrophages in BAL and expression of Siglec-1 on circulating monocytes. In the lung, IFNmod also reduced pathogenesis and attenuated pathways of inflammasome activation and stress response during acute SARS-CoV-2 infection. Using an intervention targeting both IFN-α and IFN-β pathways, this study shows that, whereas early IFN-I restrains SARS-CoV-2 replication, uncontrolled IFN-I signaling critically contributes to SARS-CoV-2 inflammation and pathogenesis in the moderate disease model of RMs.

The Stereotypic Response of the Pulmonary Vasculature to Respiratory Viral Infections: Findings in Mouse Models of SARS-CoV-2, Influenza A and Gammaherpesvirus Infections

The respiratory system is the main target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 19 (COVID-19) where acute respiratory distress syndrome is considered the leading cause of death. Changes in pulmonary blood vessels, among which an endothelialitis/endotheliitis has been particularly emphasized, have been suggested to play a central role in the development of acute lung injury. Similar vascular changes are also observed in animal models of COVID-19. The present study aimed to determine whether the latter are specific for SARS-CoV-2 infection, investigating the vascular response in the lungs of mice infected with SARS-CoV-2 and other respiratory viruses (influenza A and murine gammaherpesvirus) by in situ approaches (histology, immunohistology, morphometry) combined with RNA sequencing and bioinformatic analysis. Non-selective recruitment of monocytes and T and B cells from larger muscular veins and arteries was observed with all viruses, matched by a comparable transcriptional response. There was no evidence of endothelial cell infection in any of the models. Both the morphological investigation and the transcriptomics approach support the interpretation that the lung vasculature in mice mounts a stereotypic response to alveolar and respiratory epithelial damage. This may have implications for the treatment and management of respiratory disease in humans.

Neutrophil Activation and Immune Thrombosis Profiles Persist in Convalescent COVID-19

PURPOSE

Following a severe COVID-19 infection, a proportion of individuals develop prolonged symptoms. We investigated the immunological dysfunction that underlies the persistence of symptoms months after the resolution of acute COVID-19.

METHODS

We analyzed cytokines, cell phenotypes, SARS-CoV-2 spike-specific and neutralizing antibodies, and whole blood gene expression profiles in convalescent severe COVID-19 patients 1, 3, and 6 months following hospital discharge.

RESULTS

We observed persistent abnormalities until month 6 marked by (i) high serum levels of monocyte/macrophage and endothelial activation markers, chemotaxis, and hematopoietic cytokines; (ii) a high frequency of central memory CD4+ and effector CD8+ T cells; (iii) a decrease in anti-SARS-CoV-2 spike and neutralizing antibodies; and (iv) an upregulation of genes related to platelet, neutrophil activation, erythrocytes, myeloid cell differentiation, and RUNX1 signaling. We identified a "core gene signature" associated with a history of thrombotic events, with upregulation of a set of genes involved in neutrophil activation, platelet, hematopoiesis, and blood coagulation.

CONCLUSION

The lack of restoration of gene expression to a normal profile after up to 6 months of follow-up, even in asymptomatic patients who experienced severe COVID-19, signals the need to carefully extend their clinical follow-up and propose preventive measures.

A SARS-CoV-2 and influenza double hit vaccine based on RBD-conjugated inactivated influenza A virus

The circulating flu viruses merging with the ongoing COVID-19 pandemic raises a more severe threat that promotes the infectivity of SARS-CoV-2 associated with higher mortality rates. Here, we conjugated recombinant receptor binding domain (RBD) of SARS-CoV-2 spike protein onto inactivated influenza A virus (Flu) to develop a SARS-CoV-2 virus-like particle (VLP) vaccine with two-hit protection. This double-hit vaccine (Flu-RBD) not only induced protective immunities against SARS-CoV-2 but also remained functional as a flu vaccine. The Flu core improved the retention and distribution of Flu-RBD vaccine in the draining lymph nodes, with enhanced immunogenicity. In a hamster model of live SARS-CoV-2 infection, two doses of Flu-RBD efficiently protected animals against viral infection. Furthermore, Flu-RBD VLP elicited a strong neutralization activity against both SARS-CoV-2 Delta pseudovirus and wild-type influenza A H1N1 inactivated virus in mice. Overall, the Flu-RBD VLP vaccine is a promising candidate for combating COVID-19, influenza A, and coinfection.

Pulmonary embolism and deep venous thrombosis after COVID-19: long-term risk in a population-based cohort study

Background

Venous thromboembolism (VTE) (pulmonary embolism (PE) or deep venous thrombosis (DVT)) is common during acute COVID-19. Long-term excess risk has not yet been established.

Objective

To study long-term VTE risk after COVID-19.

Methods

Swedish citizens aged 18-84 years, hospitalized and/or testing positive for COVID-19 between January 1, 2020, and September 11, 2021 (exposed), stratified by initial hospitalization, were compared to matched (1:5) non-exposed population-derived subjects without COVID-19. Outcomes were incident VTE, PE or DVT recorded within 60, 60-<180, and ≥180 days. Cox regression was used for evaluation and a model adjusted for age, sex, comorbidities and socioeconomic markers developed to control for confounders.

Results

Among exposed patients, 48,861 were hospitalized for COVID-19 (mean age 60.6 years) and 894,121 were without hospitalization (mean age 41.4 years). Among patients hospitalized for COVID-19, fully adjusted hazard ratios (HRs) during 60-<180 days were 6.05 (95% confidence interval (CI) 4.80─7.62) for PE and 3.97 (CI 2.96─5.33) for DVT, compared to non-exposed with corresponding estimates among COVID-19 without hospitalization 1.17 (CI 1.01─1.35) and 0.99 (CI 0.86─1.15), based on 475 and 2,311 VTE events, respectively. Long-term (≥180 days) HRs in patients hospitalized for COVID-19 were 2.01 (CI 1.51─2.68) for PE and 1.46 (CI 1.05─2.01) for DVT while non-hospitalized had similar risk to non-exposed, based on 467 and 2,030 VTE events, respectively.

Conclusions

Patients hospitalized for COVID-19 retained an elevated excess risk of VTE, mainly PE, after 180 days, while long-term risk of VTE in individuals with COVID-19 without hospitalization was similar to the non-exposed.

Von Willebrand factor and the thrombophilia of severe COVID-19: in situ evidence from autopsies

Background

COVID-19 is accompanied by a hypercoagulable state and characterized by microvascular and macrovascular thrombotic complications. In plasma samples from patients with COVID-19, von Willebrand factor (VWF) levels are highly elevated and predictive of adverse outcomes, especially mortality. Yet, VWF is usually not included in routine coagulation analyses, and histologic evidence of its involvement in thrombus formation is lacking.

Objectives

To determine whether VWF, an acute-phase protein, is a bystander, ie, a biomarker of endothelial dysfunction, or a causal factor in the pathogenesis of COVID-19.

Methods

We compared autopsy samples from 28 patients with lethal COVID-19 to those from matched controls and systematically assessed for VWF and platelets by immunohistochemistry. The control group comprised 24 lungs, 23 lymph nodes, and 9 hearts and did not differ significantly from the COVID-19 group in age, sex, body mass index (BMI), blood group, or anticoagulant use.

Results

In lungs, assessed for platelets by immunohistochemistry for CD42b, microthrombi were more frequent in patients with COVID-19 (10/28 [36%] vs 2/24 [8%]; P = .02). A completely normal pattern of VWF was rare in both groups. Accentuated endothelial staining was found in controls, while VWF-rich thrombi were only found in patients with COVID-19 (11/28 [39%] vs 0/24 [0%], respectively; P < .01), as were NETosis thrombi enriched with VWF (7/28 [25%] vs 0/24 [0%], respectively; P < .01). Forty-six percent of the patients with COVID-19 had VWF-rich thrombi, NETosis thrombi, or both. Trends were also seen in pulmonary draining lymph nodes (7/20 [35%] vs 4/24 [17%]; P = .147), where the overall presence of VWF was very high.

Conclusion

We provide in situ evidence of VWF-rich thrombi, likely attributable to COVID-19, and suggest that VWF may be a therapeutic target in severe COVID-19.

TREM2+ and interstitial-like macrophages orchestrate airway inflammation in SARS-CoV-2 infection in rhesus macaques

The immunopathological mechanisms driving the development of severe COVID-19 remain poorly defined. Here, we utilize a rhesus macaque model of acute SARS-CoV-2 infection to delineate perturbations in the innate immune system. SARS-CoV-2 initiates a rapid infiltration of plasmacytoid dendritic cells into the lower airway, commensurate with IFNA production, natural killer cell activation, and a significant increase of blood CD14-CD16+ monocytes. To dissect the contribution of lung myeloid subsets to airway inflammation, we generate a longitudinal scRNA-Seq dataset of airway cells, and map these subsets to corresponding populations in the human lung. SARS-CoV-2 infection elicits a rapid recruitment of two macrophage subsets: CD163+MRC1-, and TREM2+ populations that are the predominant source of inflammatory cytokines. Treatment with baricitinib (Olumiant®), a JAK1/2 inhibitor is effective in eliminating the influx of non-alveolar macrophages, with a reduction of inflammatory cytokines. This study delineates the major lung macrophage subsets driving airway inflammation during SARS-CoV-2 infection.

A review of cytokine-based pathophysiology of Long COVID symptoms

The Long COVID/Post Acute Sequelae of COVID-19 (PASC) group includes patients with initial mild-to-moderate symptoms during the acute phase of the illness, in whom recovery is prolonged, or new symptoms are developed over months. Here, we propose a description of the pathophysiology of the Long COVID presentation based on inflammatory cytokine cascades and the p38 MAP kinase signaling pathways that regulate cytokine production. In this model, the SARS-CoV-2 viral infection is hypothesized to trigger a dysregulated peripheral immune system activation with subsequent cytokine release. Chronic low-grade inflammation leads to dysregulated brain microglia with an exaggerated release of central cytokines, producing neuroinflammation. Immunothrombosis linked to chronic inflammation with microclot formation leads to decreased tissue perfusion and ischemia. Intermittent fatigue, Post Exertional Malaise (PEM), CNS symptoms with "brain fog," arthralgias, paresthesias, dysautonomia, and GI and ophthalmic problems can consequently arise as result of the elevated peripheral and central cytokines. There are abundant similarities between symptoms in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). DNA polymorphisms and viral-induced epigenetic changes to cytokine gene expression may lead to chronic inflammation in Long COVID patients, predisposing some to develop autoimmunity, which may be the gateway to ME/CFS.

Molecular Analysis of SARS-CoV-2 Spike Protein-Induced Endothelial Cell Permeability and vWF Secretion

Coronavirus disease COVID-19, which is caused by severe acute respiratory syndrome coronavirus SARS-CoV-2, has become a worldwide pandemic in recent years. In addition to being a respiratory disease, COVID-19 is a ‘vascular disease’ since it causes a leaky vascular barrier and increases blood clotting by elevating von Willebrand factor (vWF) levels in the blood. In this study, we analyzed in vitro how the SARS-CoV-2 spike protein S1 induces endothelial cell (EC) permeability and its vWF secretion, and the underlying molecular mechanism for it. We showed that the SARS-CoV-2 spike protein S1 receptor-binding domain (RBD) is sufficient to induce endothelial permeability and vWF-secretion through the angiotensin-converting enzyme (ACE)2 in an ADP-ribosylation factor (ARF)6 activation-dependent manner. However, the mutants, including those in South African and South Californian variants of SARS-CoV-2, in the spike protein did not affect its induced EC permeability and vWF secretion. In addition, we have identified a signaling cascade downstream of ACE2 for the SARS-CoV-2 spike protein-induced EC permeability and its vWF secretion by using pharmacological inhibitors. The knowledge gained from this study could be useful in developing novel drugs or repurposing existing drugs for treating infections of SARS-CoV-2, particularly those strains that respond poorly to the existing vaccines.

Cationic phosphorus dendron nanomicelles deliver microRNA mimics and microRNA inhibitors for enhanced anti-inflammatory therapy of acute lung injury

The development of efficient nanomedicines to repress the repolarization of M1 phenotype macrophages and therefore inhibit pro-inflammatory cytokine overexpression for anti-inflammatory therapy is still a challenging task. We report here an original gene delivery nanoplatform based on pyrrolidinium-modified amphiphilic generation 1 phosphorus dendron (C12G1) nanomicelles with a rigid phosphorous dendron structure. The nanomicelles display higher gene delivery efficiency than the counterpart materials of pyrrolidinium-modified G1 phosphorus dendrimers, and meanwhile exhibit excellent cytocompatibility. The C12G1 nanomicelles can be employed to co-deliver the miRNA-146a mimic (miR-146a mimic) and miRNA-429 inhibitor (miR-429i) to inhibit the Toll-like receptor-4 signaling pathway and p38 mitogen-activated protein kinase signaling pathway, respectively, thus causing repression of M1 phenotype alveolar macrophage polarization. The developed C12G1/miR-mixture polyplexes enable efficient therapy of lipopolysaccharide-activated alveolar macrophages in vitro and an acute lung injury mouse model in vivo. The generated cationic phosphorus dendron nanomicelles may hold promising potential for anti-inflammatory gene therapy of other inflammatory diseases.

Induced Pluripotent Stem Cell-Derived Organoids: Their Implication in COVID-19 Modeling

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a significant global health issue. This novel virus's high morbidity and mortality rates have prompted the scientific community to quickly find the best COVID-19 model to investigate all pathological processes underlining its activity and, more importantly, search for optimal drug therapy with minimal toxicity risk. The gold standard in disease modeling involves animal and monolayer culture models; however, these models do not fully reflect the response to human tissues affected by the virus. However, more physiological 3D in vitro culture models, such as spheroids and organoids derived from induced pluripotent stem cells (iPSCs), could serve as promising alternatives. Different iPSC-derived organoids, such as lung, cardiac, brain, intestinal, kidney, liver, nasal, retinal, skin, and pancreatic organoids, have already shown immense potential in COVID-19 modeling. In the present comprehensive review article, we summarize the current knowledge on COVID-19 modeling and drug screening using selected iPSC-derived 3D culture models, including lung, brain, intestinal, cardiac, blood vessels, liver, kidney, and inner ear organoids. Undoubtedly, according to reviewed studies, organoids are the state-of-the-art approach to COVID-19 modeling.

Animal Models for the Study of SARS-CoV-2-Induced Respiratory Disease and Pathology

Emergence of the betacoronavirus SARS-CoV-2 has resulted in a historic pandemic, with millions of deaths worldwide. An unprecedented effort has been made by the medical, scientific, and public health communities to rapidly develop and implement vaccines and therapeutics to prevent and reduce hospitalizations and deaths. Although SARS-CoV-2 infection can lead to disease in many organ systems, the respiratory system is its main target, with pneumonia and acute respiratory distress syndrome as the hallmark features of severe disease. The large number of patients who have contracted COVID-19 infections since 2019 has permitted a detailed characterization of the clinical and pathologic features of the disease in humans. However, continued progress in the development of effective preventatives and therapies requires a deeper understanding of the pathogenesis of infection. Studies using animal models are necessary to complement in vitro findings and human clinical data. Multiple animal species have been evaluated as potential models for studying the respiratory disease caused by SARSCoV-2 infection. Knowing the similarities and differences between animal and human responses to infection is critical for effective translation of animal data into human medicine. This review provides a detailed summary of the respiratory disease and associated pathology induced by SARS-CoV-2 infection in humans and compares them with the disease that develops in 3 commonly used models: NHP, hamsters, and mice. The effective use of animals to study SARS-CoV-2-induced respiratory disease will enhance our understanding of SARS-CoV-2 pathogenesis, allow the development of novel preventatives and therapeutics, and aid in the preparation for the next emerging virus with pandemic potential.

Animal Models for the Study of Neurologic Manifestations Of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of the worldwide coronavirus (COVID-19) pandemic, has infected an estimated 525 million people with over 6 million deaths. Although COVID-19 is primarily a respiratory disease, an escalating number of neurologic symptoms have been reported in humans. Some neurologic symptoms, such as loss of smell or taste, are mild. However, other symptoms, such as meningoencephalitis or stroke, are potentially fatal. Along with surveys and postmortem evaluations on humans, scientists worked with several animal species to try to elucidate the causes of neurologic symptoms. Neurologic sequelae remain challenging to study due to the complexity of the nervous system and difficulties in identification and quantification of neurologic signs. We reviewed animal models used in the study of neurologic COVID-19, specifically research in mice, hamsters, ferrets, and nonhuman primates. We summarized findings on the presence and pathologic effects of SARS-CoV-2 on the nervous system. Given the need to increase understanding of COVID-19 and its effects on the nervous system, scientists must strive to obtain new information from animals to reduce mortality and morbidity with neurologic complications in humans.

Comparison of Cardiovascular Pathology In Animal Models of SARS-CoV-2 Infection: Recommendations Regarding Standardization of Research Methods

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged as the viral pathogen that led to the global COVID-19 pandemic that began in late 2019. Because SARS-CoV-2 primarily causes a respiratory disease, much research conducted to date has focused on the respiratory system. However, SARS-CoV-2 infection also affects other organ systems, including the cardiovascular system. In this critical analysis of published data, we evaluate the evidence of cardiovascular pathology in human patients and animals. Overall, we find that the presence or absence of cardiovascular pathology is reported infrequently in both human autopsy studies and animal models of SARS-CoV-2 infection. Moreover, in those studies that have reported cardiovascular pathology, we identified issues in their design and execution that reduce confidence in the conclusions regarding SARS-CoV-2 infection as a cause of significant cardiovascular pathology. Throughout this overview, we expand on these limitations and provide recommendations to ensure a high level of scientific rigor and reproducibility.

The D405N Mutation in the Spike Protein of SARS-CoV-2 Omicron BA.5 Inhibits Spike/Integrins Interaction and Viral Infection of Human Lung Microvascular Endothelial Cells

Severe COVID-19 is characterized by angiogenic features, such as intussusceptive angiogenesis, endothelialitis, and activation of procoagulant pathways. This pathological state can be ascribed to a direct SARS-CoV-2 infection of human lung ECs. Recently, we showed the capability of SARS-CoV-2 to infect ACE2-negative primary human lung microvascular endothelial cells (HL-mECs). This occurred through the interaction of an Arg-Gly-Asp (RGD) motif, endowed on the Spike protein at position 403-405, with α_vβ₃ integrin expressed on HL-mECs. HL-mEC infection promoted the remodeling of cells toward a pro-inflammatory and pro-angiogenic phenotype. The RGD motif is distinctive of SARS-CoV-2 Spike proteins up to the Omicron BA.1 subvariant. Suddenly, a dominant D405N mutation was expressed on the Spike of the most recently emerged Omicron BA.2, BA.4, and BA.5 subvariants. Here we demonstrate that the D405N mutation inhibits Omicron BA.5 infection of HL-mECs and their dysfunction because of the lack of Spike/integrins interaction. The key role of ECs in SARS-CoV-2 pathogenesis has been definitively proven. Evidence of mutations retrieving the capability of SARS-CoV-2 to infect HL-mECs highlights a new scenario for patients infected with the newly emerged SARS-CoV-2 Omicron subvariants, suggesting that they may display less severe disease manifestations than those observed with previous variants.

Involvement of NLRP3 Inflammasome in SARS-Cov-2-Induced Multiorgan Dysfunction in Patients with COVID-19: A Review of Molecular Mechanisms

Nucleotide-binding domain and leucine-rich repeat protein- 3 (NLRP3) inflammasome is a critical component of the innate immune system. The inflammasome activation is correlated with the COVID- 19 severity. Furthermore, the underlying conditions are accompanied by hyperactivation of NLRP3 inflammasome and poor outcomes. Herein, we presented the involvement of NLRP3 inflammasome in the pathogenies of SARS-CoV-2-induced multiorgan dysfunction and potential therapeutics. Overexpression of NLRP3 inflammasome components and subsequently increased levels of cytokines following viral infection leads to the cytokine storm and indirectly affects the organ functions. Besides, invading host cells via SARS-CoV-2 further activates the NLRP3 inflammasome and induces pyroptosis in immune cells, resulting in the secretion of higher levels of proinflammatory cytokines into the extracellular matrix. These events continued by induction of fibrosis and organ dysfunction following infection with SARS-CoV-2 in critically ill patients. This condition can be observed in individuals with comorbidities (e.g., diabetes, obesity, etc.) due to a primed state of immunity, which can cause severe disease or death in this population. Therefore, understanding the mechanisms underlying host-SARS-CoV-2 interaction may help to clarify the pathophysiology of SARS-CoV-2- induced multiorgan dysfunction and introduce potential therapeutic strategies.

SARS-CoV-2 induces "cytokine storm" hyperinflammatory responses in RA patients through pyroptosis

Background

The coronavirus disease (COVID-19) is a pandemic disease that threatens worldwide public health, and rheumatoid arthritis (RA) is the most common autoimmune disease. COVID-19 and RA are each strong risk factors for the other, but their molecular mechanisms are unclear. This study aims to investigate the biomarkers between COVID-19 and RA from the mechanism of pyroptosis and find effective disease-targeting drugs.

Methods

We obtained the common gene shared by COVID-19, RA (GSE55235), and pyroptosis using bioinformatics analysis and then did the principal component analysis(PCA). The Co-genes were evaluated by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and ClueGO for functional enrichment, the protein-protein interaction (PPI) network was built by STRING, and the k-means machine learning algorithm was employed for cluster analysis. Modular analysis utilizing Cytoscape to identify hub genes, functional enrichment analysis with Metascape and GeneMANIA, and NetworkAnalyst for gene-drug prediction. Network pharmacology analysis was performed to identify target drug-related genes intersecting with COVID-19, RA, and pyroptosis to acquire Co-hub genes and construct transcription factor (TF)-hub genes and miRNA-hub genes networks by NetworkAnalyst. The Co-hub genes were validated using GSE55457 and GSE93272 to acquire the Key gene, and their efficacy was assessed using receiver operating curves (ROC); SPEED2 was then used to determine the upstream pathway. Immune cell infiltration was analyzed using CIBERSORT and validated by the HPA database. Molecular docking, molecular dynamics simulation, and molecular mechanics-generalized born surface area (MM-GBSA) were used to explore and validate drug-gene relationships through computer-aided drug design.

Results

COVID-19, RA, and pyroptosis-related genes were enriched in pyroptosis and pro-inflammatory pathways(the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome complex, death-inducing signaling complex, regulation of interleukin production), natural immune pathways (Network map of SARS-CoV-2 signaling pathway, activation of NLRP3 inflammasome by SARS-CoV-2) and COVID-19-and RA-related cytokine storm pathways (IL, nuclear factor-kappa B (NF-κB), TNF signaling pathway and regulation of cytokine-mediated signaling). Of these, CASP1 is the most involved pathway and is closely related to minocycline. YY1, hsa-mir-429, and hsa-mir-34a-5p play an important role in the expression of CASP1. Monocytes are high-caspase-1-expressing sentinel cells. Minocycline can generate a highly stable state for biochemical activity by docking closely with the active region of caspase-1.

Conclusions

Caspase-1 is a common biomarker for COVID-19, RA, and pyroptosis, and it may be an important mediator of the excessive inflammatory response induced by SARS-CoV-2 in RA patients through pyroptosis. Minocycline may counteract cytokine storm inflammation in patients with COVID-19 combined with RA by inhibiting caspase-1 expression.

The role of berberine in Covid-19: potential adjunct therapy

Coronavirus disease 2019 (Covid-19) is a global diastrophic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Covid-19 leads to inflammatory, immunological, and oxidative changes, by which SARS-CoV-2 leads to endothelial dysfunction (ED), acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and multi-organ failure (MOF). Despite evidence illustrating that some drugs and vaccines effectively manage and prevent Covid-19, complementary herbal medicines are urgently needed to control this pandemic disease. One of the most used herbal medicines is berberine (BBR), which has anti-inflammatory, antioxidant, antiviral, and immune-regulatory effects; thus, BBR may be a prospective candidate against SARS-CoV-2 infection. This review found that BBR has anti-SARS-CoV-2 effects with mitigation of associated inflammatory changes. BBR also reduces the risk of ALI/ARDS in Covid-19 patients by inhibiting the release of pro-inflammatory cytokines and inflammatory signaling pathways. In conclusion, BBR has potent anti-inflammatory, antioxidant, and antiviral effects. Therefore, it can be utilized as a possible anti-SARS-CoV-2 agent. BBR inhibits the proliferation of SARS-CoV-2 and attenuates the associated inflammatory disorders linked by the activation of inflammatory signaling pathways. Indeed, BBR can alleviate ALI/ARDS in patients with severe Covid-19. In this sense, clinical trials and prospective studies are suggested to illustrate the potential role of BBR in treating Covid-19.

Inflammatory platelet production stimulated by tyrosyl-tRNA synthetase mimicking viral infection

Platelets play a role not only in hemostasis and thrombosis, but also in inflammation and innate immunity. We previously reported that an activated form of tyrosyl-tRNA synthetase (YRSACT) has an extratranslational activity that enhances megakaryopoiesis and platelet production in mice. Here, we report that YRSACT mimics inflammatory stress inducing a unique megakaryocyte (MK) population with stem cell (Sca1) and myeloid (F4/80) markers through a mechanism dependent on Toll-like receptor (TLR) activation and type I interferon (IFN-I) signaling. This mimicry of inflammatory stress by YRSACT was studied in mice infected by lymphocytic choriomeningitis virus (LCMV). Using Sca1/EGFP transgenic mice, we demonstrated that IFN-I induced by YRSACT or LCMV infection suppressed normal hematopoiesis while activating an alternative pathway of thrombopoiesis. Platelets of inflammatory origin (Sca1/EGFP+) were a relevant proportion of those circulating during recovery from thrombocytopenia. Analysis of these "inflammatory" MKs and platelets suggested their origin in myeloid/MK-biased hematopoietic stem cells (HSCs) that bypassed the classical MK-erythroid progenitor (MEP) pathway to replenish platelets and promote recovery from thrombocytopenia. Notably, inflammatory platelets displayed enhanced agonist-induced activation and procoagulant activities. Moreover, myeloid/MK-biased progenitors and MKs were mobilized from the bone marrow, as evidenced by their presence in the lung microvasculature within fibrin-containing microthrombi. Our results define the function of YRSACT in platelet generation and contribute to elucidate platelet alterations in number and function during viral infection.

Platelet in thrombo-inflammation: Unraveling new therapeutic targets

In the broad range of human diseases, thrombo-inflammation appears as a clinical manifestation. Clinically, it is well characterized in context of superficial thrombophlebitis that is recognized as thrombosis and inflammation of superficial veins. However, it is more hazardous when developed in the microvasculature of injured/inflamed/infected tissues and organs. Several diseases like sepsis and ischemia-reperfusion can cause formation of microvascular thrombosis subsequently leading to thrombo-inflammation. Thrombo-inflammation can also occur in cases of antiphospholipid syndrome, preeclampsia, sickle cell disease, bacterial and viral infection. One of the major contributors to thrombo-inflammation is the loss of normal anti-thrombotic and anti-inflammatory potential of the endothelial cells of vasculature. This manifest itself in the form of dysregulation of the coagulation pathway and complement system, pathologic platelet activation, and increased recruitment of leukocyte within the microvasculature. The role of platelets in hemostasis and formation of thrombi under pathologic and non-pathologic conditions is well established. Platelets are anucleate cells known for their essential role in primary hemostasis and the coagulation pathway. In recent years, studies provide strong evidence for the critical involvement of platelets in inflammatory processes like acute ischemic stroke, and viral infections like Coronavirus disease 2019 (COVID-19). This has encouraged the researchers to investigate the contribution of platelets in the pathology of various thrombo-inflammatory diseases. The inhibition of platelet surface receptors or their intracellular signaling which mediate initial platelet activation and adhesion might prove to be suitable targets in thrombo-inflammatory disorders. Thus, the present review summarizes the concept and mechanism of platelet signaling and briefly discuss their role in sterile and non-sterile thrombo-inflammation, with the emphasis on role of platelets in COVID-19 induced thrombo-inflammation. The aim of this review is to summarize the recent developments in deciphering the role of the platelets in thrombo-inflammation and discuss their potential as pharmaceutical targets.

Renal arcuate vein thrombosis-induced acute kidney injury: a rare multiple-Hit-mediated disease

Background

Renal arcuate vein thrombosis (RAVT) is a rare and recently recognized cause of acute kidney injury (AKI) in young adults. However, the precise incidence and underlying pathophysiologic mechanisms leading to AKI in these patients remain elusive.

Methods

This study included all patients who underwent a kidney biopsy over a 40-month period sent to the pathology department of Necker-Enfants Malades Hospital, with evidence of RAVT. We performed coagulation tests, genetic testing for thrombophilia, complete urine toxicologic screening and kidney metagenomic sequencing to identify an underlying cause of thrombosis.

Results

We report five pediatric cases of RAVT discovered on kidney biopsy performed in the setting of unexplained AKI. Investigations did not reveal an underlying cause of thrombosis but only a significant nonsteroidal anti-inflammatory drugs (NSAIDs) use was reported in 4/5 patients, supporting a potential link between NSAIDs use and RAVT. By performing metagenomic sequencing on kidney biopsy samples, we detected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in the kidney of one patient. These results suggest that systemic SARS-CoV-2 infection may also be a key contributing factor of renal thrombosis, particularly by inducing potential endothelial disruption.

Conclusions

In conclusion, RAVT-induced AKI appears to be a multiple hit-mediated disease in which NSAIDs consumption and viral infection such as SARS-CoV-2 may be crucial contributing factors. These findings may have significant public health implications given the prevalence of NSAIDs use in the general population. Increased awareness and additional study of future cases may lead to a better understanding of this rare cause of AKI in children and young adults.

Role of SARS-CoV-2-induced Cytokine Storm in Multi-Organ Failure: Molecular Pathways and Potential Therapeutic Options

Coronavirus disease 2019 (COVID-19) outbreak has become a global public health emergency and has led to devastating results. Mounting evidence proposes that the disease causes severe pulmonary involvement and influences different organs, leading to a critical situation named multi-organ failure. It is yet to be fully clarified how the disease becomes so deadly in some patients. However, it is proven that a condition called “cytokine storm” is involved in the deterioration of COVID-19. Although beneficial, sustained production of cytokines and overabundance of inflammatory mediators causing cytokine storm can lead to collateral vital organ damages. Furthermore, cytokine storm can cause post-COVID-19 syndrome (PCS), an important cause of morbidity after the acute phase of COVID-19. Herein, we aim to explain the possible pathophysiology mechanisms involved in COVID-19-related cytokine storm and its association with multi-organ failure and PCS. We also discuss the latest advances in finding the potential therapeutic targets to control cytokine storm wishing to answer unmet clinical demands for treatment of COVID-19.

Characteristics of animal models for COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19), the most consequential pandemic of this century, threatening human health and public safety. SARS-CoV-2 has been continuously evolving through mutation of its genome and variants of concern have emerged. The World Health Organization R&D Blueprint plan convened a range of expert groups to develop animal models for COVID-19, a core requirement for the prevention and control of SARS-CoV-2 pandemic. The animal model construction techniques developed during the SARS-CoV and MERS-CoV pandemics were rapidly deployed and applied in the establishment of COVID-19 animal models. To date, a large number of animal models for COVID-19, including mice, hamsters, minks and nonhuman primates, have been established. Infectious diseases produce unique manifestations according to the characteristics of the pathogen and modes of infection. Here we classified animal model resources around the infection route of SARS-CoV-2, and summarized the characteristics of the animal models constructed via transnasal, localized, and simulated transmission routes of infection.

Modulation of type I interferon responses potently inhibits SARS-CoV-2 replication and inflammation in rhesus macaques

Type-I interferons (IFN-I) are critical mediators of innate control of viral infections, but also drive recruitment of inflammatory cells to sites of infection, a key feature of severe COVID-19. Here, and for the first time, IFN-I signaling was modulated in rhesus macaques (RMs) prior to and during acute SARS-CoV-2 infection using a mutated IFNα2 (IFN-modulator; IFNmod), which has previously been shown to reduce the binding and signaling of endogenous IFN-I. In SARS-CoV-2-infected RMs, IFNmod reduced both antiviral and inflammatory ISGs. Notably, IFNmod treatment resulted in a potent reduction in (i) SARS-CoV-2 viral load in Bronchoalveolar lavage (BAL), upper airways, lung, and hilar lymph nodes; (ii) inflammatory cytokines, chemokines, and CD163+MRC1-inflammatory macrophages in BAL; and (iii) expression of Siglec-1, which enhances SARS-CoV-2 infection and predicts disease severity, on circulating monocytes. In the lung, IFNmod also reduced pathogenesis and attenuated pathways of inflammasome activation and stress response during acute SARS-CoV-2 infection. This study, using an intervention targeting both IFN-α and IFN-β pathways, shows that excessive inflammation driven by type 1 IFN critically contributes to SARS-CoV-2 pathogenesis in RMs, and demonstrates the potential of IFNmod to limit viral replication, SARS-CoV-2 induced inflammation, and COVID-19 severity.

An Immune Response to Heterologous ChAdOx1/BNT162b2 Vaccination against COVID-19: Evaluation of the anti-RBD Specific IgG Antibodies Titers and Interferon Gamma Release Assay (IGRA) Test Results

This study aimed to assess the magnitude of anti-SARS-CoV-2 immunoglobulin G (IgG) titers and Interferon-Gamma Release Assay (IGRA) test results following administration of booster BNT162b2 in 48 ChAd-primed participants (vaccination schedule: ChAd/ChAd/BNT). Whole blood samples were collected: first, before and second, 21 days after the booster dose. The IgG level was measured using chemiluminescent immunoassay; the intensity of the T-cell response—IFNγ concentration—was assessed using IGRA test. At 21 days after the booster, all subjects achieved reactive/positive anti-SARS-CoV-2 IgG, and IGRA test results showed a significant increase compared to the results before booster administration. We compared the results before and after the booster between participants with and without prior history of COVID-19. The IFNγ concentrations in both cohorts were higher in convalescents (both before booster and 21 days after). The IgG titers were subtly lower in COVID-19 convalescents than in naïve but without statistical significance. Data on cell-mediated immunity are scarce, especially with regard to the general population. A better understanding of the complexity of the immune response to SARS-CoV-2 could contribute to developing more effective vaccination strategies.

Vandetanib Blocks the Cytokine Storm in SARS-CoV-2-Infected Mice

The portfolio of SARS-CoV-2 small molecule drugs is currently limited to a handful that are either approved (remdesivir), emergency approved (dexamethasone, baricitinib, paxlovid, and molnupiravir), or in advanced clinical trials. Vandetanib is a kinase inhibitor which targets the vascular endothelial growth factor receptor (VEGFR), the epidermal growth factor receptor (EGFR), as well as the RET-tyrosine kinase. In the current study, it was tested in different cell lines and showed promising results on inhibition versus the toxic effect on A549-hACE2 cells (IC50 0.79 μM) while also showing a reduction of >3 log TCID50/mL for HCoV-229E. The in vivo efficacy of vandetanib was assessed in a mouse model of SARS-CoV-2 infection and statistically significantly reduced the levels of IL-6, IL-10, and TNF-α and mitigated inflammatory cell infiltrates in the lungs of infected animals but did not reduce viral load. Vandetanib also decreased CCL2, CCL3, and CCL4 compared to the infected animals. Vandetanib additionally rescued the decreased IFN-1β caused by SARS-CoV-2 infection in mice to levels similar to that in uninfected animals. Our results indicate that the FDA-approved anticancer drug vandetanib is worthy of further assessment as a potential therapeutic candidate to block the COVID-19 cytokine storm.

Premortem Skin Biopsy Assessing Microthrombi, Interferon Type I Antiviral and Regulatory Proteins, and Complement Deposition Correlates with Coronavirus Disease 2019 Clinical Stage

Apart from autopsy, tissue correlates of coronavirus disease 2019 (COVID-19) clinical stage are lacking. In the current study, cutaneous punch biopsy specimens of 15 individuals with severe/critical COVID-19 and six with mild/moderate COVID-19 were examined. Evidence for arterial and venous microthrombi, deposition of C5b-9 and MASP2 (representative of alternative and lectin complement pathways, respectively), and differential expression of interferon type I-driven antiviral protein MxA (myxovirus resistance A) versus SIN3A, a promoter of interferon type I-based proinflammatory signaling, were assessed. Control subjects included nine patients with sepsis-related acute respiratory distress syndrome (ARDS) and/or acute kidney injury (AKI) pre-COVID-19. Microthrombi were detected in 13 (87%) of 15 patients with severe/critical COVID-19 versus zero of six patients with mild/moderate COVID-19 (P < 0.001) and none of the nine patients with pre-COVID-19 ARDS/AKI (P < 0.001). Cells lining the microvasculature staining for spike protein of severe acute respiratory syndrome coronavirus 2, the etiologic agent of COVID-19, also expressed tissue factor. C5b-9 deposition occurred in 13 (87%) of 15 patients with severe/critical COVID-19 versus zero of six patients with mild/moderate COVID-19 (P < 0.001) and none of the nine patients with pre-COVID-19 ARDS/AKI (P < 0.001). MASP2 deposition was also restricted to severe/critical COVID-19 cases. MxA expression occurred in all six mild/moderate versus two (15%) of 13 severe/critical cases (P < 0.001) of COVID-19. In contrast, SIN3A was restricted to severe/critical COVID-19 cases co-localizing with severe acute respiratory syndrome coronavirus 2 spike protein. SIN3A was also elevated in plasma of patients with severe/critical COVID-19 versus control subjects (P ≤ 0.02). In conclusion, the study identified premortem tissue correlates of COVID-19 clinical stage using skin. If validated in a longitudinal cohort, this approach could identify individuals at risk for disease progression and enable targeted interventions.

Impact of Immunotherapies on SARS-CoV-2-Infections and Other Respiratory Tract Infections during the COVID-19 Winter Season in IBD Patients

BACKGROUND

COVID-19 represents one of the most significant medical problems of our time.

AIMS

This study is focused on the question whether patients with inflammatory bowel disease (IBD) who receive immunotherapies are more vulnerable to respiratory tract infections and SARS-CoV-2 infections in comparison to medical staff, as a cohort with an increased infection risk, and to the general population in a COVID-19 hotspot.

METHODS

We analysed data regarding respiratory tract infections that were collected in our IBD registry and compared them with corresponding data from medical employees in our associated Isarklinikum hospital and from the healthy general population in Munich, Germany, over the same time frame in April and June 2020. Patients were tested for SARS-CoV-2 immunoglobulins (Ig).

RESULTS

Symptoms of respiratory tract infections occurred equally frequent in IBD patients with immunotherapies as compared to those without. Older age (>49 years), TNF-inhibitor, and ustekinumab treatment showed a significantly protective role in preventing respiratory tract symptomatic COVID-19 infections that occurred in 0.45% of all our 1.091 IBD patients. Of those, 1.8% were positive for SARS-CoV-2 Ig, identically to the general population of Munich with also 1.8% positivity. Whilst more than 3% of all COVID-19 subjects of the general population died during the first wave, none of our IBD patients died or needed referral to the ICU or oxygen treatment.

CONCLUSIONS

In our study, IBD patients are as susceptible to respiratory tract infections or SARS-CoV-2 as the normal population. There is no evidence of an association between IBD therapies and increased risk of COVID-19. Interestingly, a reduced rate of COVID-19 deaths in IBD patients, the majority on immunomodulator therapy, was observed, compared to the general population. Therefore, no evidence was found to suggest that IBD medication should be withheld, and adherence should be encouraged to prevent flares. In addition to older age (>49 years), TNF inhibitors and ustekinumab show a protective role in preventing respiratory tract infections. In addition, these results add to the growing evidence that supports further investigation of TNF inhibitors as a possible treatment in the early course of severe COVID-19.

Targeting thromboinflammation in COVID-19 - A narrative review of the potential of C1 inhibitor to prevent disease progression

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 is associated with a clinical spectrum ranging from asymptomatic carriers to critically ill patients with complications including thromboembolic events, myocardial injury, multisystemic inflammatory syndromes and death. Since the beginning of the pandemic several therapeutic options emerged, with a multitude of randomized trials, changing the medical landscape of COVID-19. The effect of various monoclonal antibodies, antiviral, anti-inflammatory and anticoagulation drugs have been studied, and to some extent, implemented into clinical practice. In addition, a multitude of trials improved the understanding of the disease and emerging evidence points towards a significant role of the complement system, kallikrein-kinin, and contact activation system as drivers of disease in severe COVID-19. Despite their involvement in COVID-19, treatments targeting these plasmatic cascades have neither been systematically studied nor introduced into clinical practice, and randomized studies with regards to these treatments are scarce. Given the multiple-action, multiple-target nature of C1 inhibitor (C1-INH), the natural inhibitor of these cascades, this drug may be an interesting candidate to prevent disease progression and combat thromboinflammation in COVID-19. This narrative review will discuss the current evidence with regards to the involvement of these plasmatic cascades as well as endothelial cells in COVID-19. Furthermore, we summarize the evidence of C1-INH in COVID-19 and potential benefits and pitfalls of C1-INH treatment in COVID-19.

Impaired tryptophan metabolism in the gastrointestinal tract of patients with critical coronavirus disease 2019

Introduction

Coronavirus disease 2019 (COVID-19) is still causing a global pandemic. But the mechanism of COVID-19 severity is not well elucidated.

Materials and methods

We conducted two single-center observational studies of patients with COVID-19. In the first study, the enrolled patients were distinguished based on critical vs. non-critical COVID-19. We collected blood samples from the patients at admission to measure markers related to inflammation and thrombosis and stool samples to analyze the fecal microbiome, metabolome, and calprotectin level. In the second study, we collected ileum and colon tissue samples from patients with critical COVID-19 who required colonoscopy due to severe gastrointestinal symptoms and analyzed mucosal gene expression.

Results

A total of 19 blood samples and 10 stool samples were collected. Interleukin (IL)-6 was the only serum inflammatory marker with significantly higher levels in the critical group than in the non-critical group. The fecal calprotectin level in the critical group was significantly higher than that in the non-critical group (P = 0.03), regardless of the presence of gastrointestinal symptoms. Stool metabolomic analysis showed that the level of indole-3-propionic acid, a ligand for aryl hydrocarbon receptor (AhR), was markedly decreased in the critical group compared to that in the non-critical group (P = 0.01). The expression of genes involved in tryptophan metabolism, including ACE2, AHR, CARD9, and IL22, was downregulated in the ileum of critical COVID-19 patients who required a colonoscopy.

Discussion

Critical COVID-19 patients have gastrointestinal inflammation potentially caused by impaired tryptophan metabolism in the small intestine due to decreased expression of genes involved in tryptophan metabolism.

Coordinated innate and T-cell immune responses in mild COVID-19 patients from household contacts of COVID-19 cases during the first pandemic wave

Objective

To better define the immunopathogenesis of COVID-19, the present study aims to characterize the early immune responses to SARS-CoV-2 infection in household contacts of COVID-19 cases. In particular, innate, T- and B-cell specific responses were evaluated over time.

Methods

Household contacts of COVID-19 cases screened for SARS−CoV−2 infection by nasopharyngeal swab for surveillance purposes were enrolled (T0, n=42). Of these, 28 subjects returned for a follow-up test (T1). The innate response was assessed by detecting a panel of soluble factors by multiplex-technology in plasma samples. Cell-mediated response was evaluated by measuring interferon (IFN)-γ levels by ELISA in plasma harvested from whole-blood stimulated with SARS−CoV−2 peptide pools, including spike (S), nucleocapsid (N) and membrane (M) proteins. The serological response was assessed by quantifying anti-Receptor-Binding-Domain (RBD), anti-Nucleocapsid (N), whole virus indirect immunofluorescence, and neutralizing antibodies.

Results

At T0, higher levels of plasmatic IFN-α, IL-1ra, MCP-1 and IP-10, and lower levels of IL-1β, IL-9, MIP-1β and RANTES were observed in subjects with positive swab compared to individuals with a negative one (p<0.05). Plasmatic IFN-α was the only cytokine detectable in subjects with positive SARS-CoV-2 swabs with high accuracy for swab score positivity (0.93, p<0.0001). Among subjects with positive swabs, significant negative correlations were found among the RT-PCR cycle threshold values reported for genes S and N and IFN-α or IP-10 levels. At T0, the IFN-γ T-cell specific response was detected in 50% (5/10) of subjects with positive swab, while anti-RBD/anti-N antibodies showed a positivity rate of 10% (1/10).

At T1, the IFN-γ T-cell specific response was detected in most of the confirmed-infection subjects (77.8%, 7/9), whereas the serological response was still observed in a minority of them (44.4%, 4/9). Overall, the swab test showed a moderate concordance with the T-cell response (78.6%, k=0.467), and a scarce concordance with the serological one (72.9%, k=0.194).

Conclusions

Plasmatic IFN-α and the IFN-γ T-cell specific response appear early even in the absence of seroconversion, and show a greater positivity rate than the serological response in household contacts with positive swab.