Sulforaphane exhibits antiviral activity against pandemic SARS-CoV-2 and seasonal HCoV-OC43 coronaviruses in vitro and in mice.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), has incited a global health crisis. Currently, there are limited therapeutic options for the prevention and treatment of SARS-CoV-2 infections. We evaluated the antiviral activity of sulforaphane (SFN), the principal biologically active phytochemical derived from glucoraphanin, the naturally occurring precursor present in high concentrations in cruciferous vegetables. SFN inhibited in vitro replication of six strains of SARS-CoV-2, including Delta and Omicron, as well as that of the seasonal coronavirus HCoV-OC43. Further, SFN and remdesivir interacted synergistically to inhibit coronavirus infection in vitro. Prophylactic administration of SFN to K18-hACE2 mice prior to intranasal SARS-CoV-2 infection significantly decreased the viral load in the lungs and upper respiratory tract and reduced lung injury and pulmonary pathology compared to untreated infected mice. SFN treatment diminished immune cell activation in the lungs, including significantly lower recruitment of myeloid cells and a reduction in T cell activation and cytokine production. Our results suggest that SFN should be explored as a potential agent for the prevention or treatment of coronavirus infections.

Sex Differences in Lung Imaging and SARS-CoV-2 Antibody Responses in a COVID-19 Golden Syrian Hamster Model.

In the coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more severe outcomes are reported in males than in females, including hospitalizations and deaths. Animal models can provide an opportunity to mechanistically interrogate causes of sex differences in the pathogenesis of SARS-CoV-2. Adult male and female golden Syrian hamsters (8 to 10 weeks of age) were inoculated intranasally with 105 50% tissue culture infective dose (TCID50) of SARS-CoV-2/USA-WA1/2020 and euthanized at several time points during the acute (i.e., virus actively replicating) and recovery (i.e., after the infectious virus has been cleared) phases of infection. There was no mortality, but infected male hamsters experienced greater morbidity, losing a greater percentage of body mass, developed more extensive pneumonia as noted on chest computed tomography, and recovered more slowly than females. Treatment of male hamsters with estradiol did not alter pulmonary damage. Virus titers in respiratory tissues, including nasal turbinates, trachea, and lungs, and pulmonary cytokine concentrations, including interferon-ß (IFN-ß) and tumor necrosis factor-α (TNF-α), were comparable between the sexes. However, during the recovery phase of infection, females mounted 2-fold greater IgM, IgG, and IgA responses against the receptor-binding domain of the spike protein (S-RBD) in both plasma and respiratory tissues. Female hamsters also had significantly greater IgG antibodies against whole-inactivated SARS-CoV-2 and mutant S-RBDs as well as virus-neutralizing antibodies in plasma. The development of an animal model to study COVID-19 sex differences will allow for a greater mechanistic understanding of the SARS-CoV-2-associated sex differences seen in the human population. IMPORTANCE Men experience more severe outcomes from coronavirus disease 2019 (COVID-19) than women. Golden Syrian hamsters were used to explore sex differences in the pathogenesis of a human isolate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). After inoculation, male hamsters experienced greater sickness, developed more severe lung pathology, and recovered more slowly than females. Sex differences in disease could not be reversed by estradiol treatment in males and were not explained by either virus replication kinetics or the concentrations of inflammatory cytokines in the lungs. During the recovery period, antiviral antibody responses in the respiratory tract and plasma, including to newly emerging SARS-CoV-2 variants, were greater in female than in male hamsters. Greater lung pathology during the acute phase combined with lower antiviral antibody responses during the recovery phase of infection in males than in females illustrate the utility of golden Syrian hamsters as a model to explore sex differences in the pathogenesis of SARS-CoV-2 and vaccine-induced immunity and protection.

Functional characterization of CD4+ T cell receptors crossreactive for SARS-CoV-2 and endemic coronaviruses.

BACKGROUNDRecent studies have reported T cell immunity to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in unexposed donors, possibly due to crossrecognition by T cells specific for common cold coronaviruses (CCCs). True T cell crossreactivity, defined as the recognition by a single TCR of more than one distinct peptide-MHC ligand, has never been shown in the context of SARS-CoV-2.METHODSWe used the viral functional expansion of specific T cells (ViraFEST) platform to identify T cell responses crossreactive for the spike (S) glycoproteins of SARS-CoV-2 and CCCs at the T cell receptor (TCR) clonotype level in convalescent COVID-19 patients (CCPs) and SARS-CoV-2-unexposed donors. Confirmation of SARS-CoV-2/CCC crossreactivity and assessments of functional avidity were performed using a TCR cloning and transfection system.RESULTSMemory CD4+ T cell clonotypes that crossrecognized the S proteins of SARS-CoV-2 and at least one other CCC were detected in 65% of CCPs and unexposed donors. Several of these TCRs were shared among multiple donors. Crossreactive T cells demonstrated significantly impaired SARS-CoV-2-specific proliferation in vitro relative to monospecific CD4+ T cells, which was consistent with lower functional avidity of their TCRs for SARS-CoV-2 relative to CCC.CONCLUSIONSOur data confirm, for what we believe is the first time, the existence of unique memory CD4+ T cell clonotypes crossrecognizing SARS-CoV-2 and CCCs. The lower avidity of crossreactive TCRs for SARS-CoV-2 may be the result of antigenic imprinting, such that preexisting CCC-specific memory T cells have reduced expansive capacity upon SARS-CoV-2 infection. Further studies are needed to determine how these crossreactive T cell responses affect clinical outcomes in COVID-19 patients.FUNDINGNIH funding (U54CA260492, P30CA006973, P41EB028239, R01AI153349, R01AI145435-A1, R21AI149760, and U19A1088791) was provided by the National Institute of Allergy and Infectious Diseases, the National Cancer Institute, and the National Institute of Biomedical Imaging and Bioengineering. The Bloomberg~Kimmel Institute for Cancer Immunotherapy, The Johns Hopkins University Provost, and The Bill and Melinda Gates Foundation provided funding for this study.

Imaging Enterobacterales infections in patients using pathogen-specific positron emission tomography.

Enterobacterales represent the largest group of bacterial pathogens in humans and are responsible for severe, deep-seated infections, often resulting in sepsis or death. They are also a prominent cause of multidrug-resistant (MDR) infections, and some species are recognized as biothreat pathogens. Tools for noninvasive, whole-body analysis that can localize a pathogen with specificity are needed, but no such technology currently exists. We previously demonstrated that positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-d-sorbitol (18F-FDS) can selectively detect Enterobacterales infections in murine models. Here, we demonstrate that uptake of 18F-FDS by bacteria occurs via a metabolically conserved sorbitol-specific pathway with rapid in vitro 18F-FDS uptake noted in clinical strains, including MDR isolates. Whole-body 18F-FDS PET/computerized tomography (CT) in 26 prospectively enrolled patients with either microbiologically confirmed Enterobacterales infection or other pathologies demonstrated that 18F-FDS PET/CT was safe, could rapidly detect and localize Enterobacterales infections due to drug-susceptible or MDR strains, and differentiated them from sterile inflammation or cancerous lesions. Repeat imaging in the same patients monitored antibiotic efficacy with decreases in PET signal correlating with clinical improvement. To facilitate the use of 18F-FDS, we developed a self-contained, solid-phase cartridge to rapidly (<10 min) formulate ready-to-use 18F-FDS from commercially available 2-deoxy-2-[18F]fluoro-d-glucose (18F-FDG) at room temperature. In a hamster model, 18F-FDS PET/CT also differentiated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia from secondary Klebsiella pneumoniae pneumonia-a leading cause of complications in hospitalized patients with COVID-19. These data support 18F-FDS as an innovative and readily available, pathogen-specific PET technology with clinical applications.

Metabolic programs define dysfunctional immune responses in severe COVID-19 patients.

It is unclear why some SARS-CoV-2 patients readily resolve infection while others develop severe disease. By interrogating metabolic programs of immune cells in severe and recovered coronavirus disease 2019 (COVID-19) patients compared with other viral infections, we identify a unique population of T cells. These T cells express increased Voltage-Dependent Anion Channel 1 (VDAC1), accompanied by gene programs and functional characteristics linked to mitochondrial dysfunction and apoptosis. The percentage of these cells increases in elderly patients and correlates with lymphopenia. Importantly, T cell apoptosis is inhibited in vitro by targeting the oligomerization of VDAC1 or blocking caspase activity. We also observe an expansion of myeloid-derived suppressor cells with unique metabolic phenotypes specific to COVID-19, and their presence distinguishes severe from mild disease. Overall, the identification of these metabolic phenotypes provides insight into the dysfunctional immune response in acutely ill COVID-19 patients and provides a means to predict and track disease severity and/or design metabolic therapeutic regimens.

COVID-19 and myeloid cells: complex interplay correlates with lung severity.

COVID-19 spans a wide range of symptoms, sometimes with profound immune system involvement. How immune cell subsets change during the disease course and with disease severity needs further study. While myeloid cells have been shown to initiate and maintain responses to pneumonia and lung inflammation, often playing a role in resolution, their involvement with COVID-19 remains unknown. In this issue of the JCI, Sánchez-Cerrillo and Landete et al. investigated DCs and monocytes from blood and bronchial secretions of patients with varying COVID-19 severity and with healthy controls. The authors conclude that circulating monocytes and DCs migrate from the blood into the inflamed lungs. While sampling differences in sex, collection timing, bacteria/fungal infection, and corticosteroid treatment limit interpretation, we believe that reprogramming monocyte or macrophages by targeting immunometabolism, epigenetics, or the cytokine milieu holds promise in resolving lung inflammation associated with COVID-19.

Metabolic programs define dysfunctional immune responses in severe COVID-19 patients.

It remains unclear why some patients infected with SARS-CoV-2 readily resolve infection while others develop severe disease. To address this question, we employed a novel assay to interrogate immune-metabolic programs of T cells and myeloid cells in severe and recovered COVID-19 patients. Using this approach, we identified a unique population of T cells expressing high H3K27me3 and the mitochondrial membrane protein voltage-dependent anion channel (VDAC), which were expanded in acutely ill COVID-19 patients and distinct from T cells found in patients infected with hepatitis c or influenza and in recovered COVID-19. Increased VDAC was associated with gene programs linked to mitochondrial dysfunction and apoptosis. High-resolution fluorescence and electron microscopy imaging of the cells revealed dysmorphic mitochondria and release of cytochrome c into the cytoplasm, indicative of apoptosis activation. The percentage of these cells was markedly increased in elderly patients and correlated with lymphopenia. Importantly, T cell apoptosis could be inhibited in vitro by targeting the oligomerization of VDAC or blocking caspase activity. In addition to these T cell findings, we also observed a robust population of Hexokinase II+ polymorphonuclear-myeloid derived suppressor cells (PMN-MDSC), exclusively found in the acutely ill COVID-19 patients and not the other viral diseases. Finally, we revealed a unique population of monocytic MDSC (M-MDSC) expressing high levels of carnitine palmitoyltransferase 1a (CPT1a) and VDAC. The metabolic phenotype of these cells was not only highly specific to COVID-19 patients but the presence of these cells was able to distinguish severe from mild disease. Overall, the identification of these novel metabolic phenotypes not only provides insight into the dysfunctional immune response in acutely ill COVID-19 patients but also provide a means to predict and track disease severity as well as an opportunity to design and evaluate novel metabolic therapeutic regimens.