Shift of lung macrophage composition is associated with COVID-19 disease severity and recovery

H2 inhalation therapy in patients with moderate COVID-19 (H2COVID): a prospective ascending-dose phase I clinical trial

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has triggered a serious global health crisis, resulting in millions of reported deaths since its initial identification in China in November 2019. The global disparities in immunization access emphasize the urgent need for ongoing research into therapeutic interventions. This study focuses on the potential use of molecular dihydrogen (H2) inhalation as an adjunctive treatment for COVID-19. H2 therapy shows promise in inhibiting intracellular signaling pathways associated with inflammation, particularly when administered early in conjunction with nasal oxygen therapy. This phase I study, characterized by an open-label, prospective, monocentric, and single ascending-dose design, seeks to assess the safety and tolerability of the procedure in individuals with confirmed SARS-CoV-2 infection. Employing a 3 + 3 design, the study includes three exposure durations (target durations): 1 day (D1), 3 days (D2), and 6 days (D3). We concluded that the maximum tolerated duration is at least 3 days. Every patient showed clinical improvement and excellent tolerance to H2 therapy. To the best of our knowledge, this phase I clinical trial is the first to establish the safety of inhaling a mixture of H2 (3.6%) and N2 (96.4%) in hospitalized COVID-19 patients. The original device and method employed ensure the absence of explosion risk. The encouraging outcomes observed in the 12 patients included in the study justify further exploration through larger, controlled clinical trials.

CLINICAL TRIALS

This study is registered with ClinicalTrials.gov as NCT04633980.

The IL-4/13-induced production of M2 chemokines by human lung macrophages is enhanced by adenosine and PGE2

BACKGROUND AND PURPOSE

Lung macrophages (LMs) are critically involved in respiratory diseases. The primary objective of the present study was to determine whether or not an adenosine analog (NECA) and prostaglandin E2 (PGE2) affected the interleukin (IL)-4- and IL-13-induced release of M2a chemokines (CCL13, CCL17, CCL18, and CCL22) by human LMs.

EXPERIMENTAL APPROACH

Primary macrophages isolated from resected human lungs were incubated with NECA, PGE2, roflumilast, or vehicle and stimulated with IL-4 or IL-13 for 24 h. The levels of chemokines and PGE2 in the culture supernatants were measured using ELISAs and enzyme immunoassays.

KEY RESULTS

Exposure to IL-4 (10 ng/mL) and IL-13 (50 ng/mL) was associated with greater M2a chemokine production but not PGE2 production. PGE2 (10 ng/mL) and NECA (10-6 M) induced the production of M2a chemokines to a lesser extent but significantly enhanced the IL-4/IL-13-induced production of these chemokines. At either a clinically relevant concentration (10-9 M) or at a concentration (10-7 M) that fully inhibited phosphodiesterase 4 (PDE4) activity, roflumilast did not increase the production of M2a chemokines and did not modulate their IL-13-induced production, regardless of the presence or absence of PGE2.

CONCLUSIONS

NECA and PGE2 enhanced the IL-4/IL-13-induced production of M2a chemokines. The inhibition of PDE4 by roflumilast did not alter the production of these chemokines. These results contrast totally with the previously reported inhibitory effects of NECA, PGE2, and PDE4 inhibitors on the lipopolysaccharide-induced release of tumor necrosis factor alpha and M1 chemokines in human LMs.

Proteomic profiling identifies biomarkers of COVID-19 severity

SARS-CoV-2 infection remains a major public health concern, particularly for the aged and those individuals with co-morbidities at risk for developing severe COVID-19. Understanding the pathogenesis and biomarkers associated with responses to SARS-CoV-2 infection remain critical components in developing effective therapeutic approaches, especially in cases of severe and long-COVID-19. In this study blood plasma protein expression was compared in subjects with mild, moderate, and severe COVID-19 disease. Evaluation of an inflammatory protein panel confirms upregulation of proteins including TNFβ, IL-6, IL-8, IL-12, already associated with severe cytokine storm and progression to severe COVID-19. Importantly, we identify several proteins not yet associated with COVID-19 disease, including mesothelin (MSLN), that are expressed at significantly higher levels in severe COVID-19 subjects. In addition, we find a subset of markers associated with T-cell and dendritic cell responses to viral infection that are significantly higher in mild cases and decrease in expression as severity of COVID-19 increases, suggesting that an immediate and effective activation of T-cells is critical in modulating disease progression. Together, our findings identify new targets for further investigation as therapeutic approaches for the treatment of SARS-CoV-2 infection and prevention of complications of severe 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.

GPR183 antagonism reduces macrophage infiltration in influenza and SARS-CoV-2 infection

RATIONALE

Severe viral respiratory infections are often characterised by extensive myeloid cell infiltration and activation and persistent lung tissue injury. However, the immunological mechanisms driving excessive inflammation in the lung remain poorly understood.

OBJECTIVES

To identify the mechanisms that drive immune cell recruitment in the lung during viral respiratory infections and identify novel drug targets to reduce inflammation and disease severity.

METHODS

Preclinical murine models of influenza A virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

RESULTS

Oxidised cholesterols and the oxysterol-sensing receptor GPR183 were identified as drivers of monocyte/macrophage infiltration to the lung during influenza A virus (IAV) and SARS-CoV-2 infection. Both IAV and SARS-CoV-2 infection upregulated the enzymes cholesterol 25-hydroxylase (CH25H) and cytochrome P450 family 7 subfamily member B1 (CYP7B1) in the lung, resulting in local production of the oxidised cholesterols 25-hydroxycholesterol (25-OHC) and 7α,25-dihydroxycholesterol (7α,25-OHC). Loss-of-function mutation of Gpr183 or treatment with a GPR183 antagonist reduced macrophage infiltration and inflammatory cytokine production in the lungs of IAV- or SARS-CoV-2-infected mice. The GPR183 antagonist significantly attenuated the severity of SARS-CoV-2 infection and viral loads. Analysis of single-cell RNA-sequencing data on bronchoalveolar lavage samples from healthy controls and COVID-19 patients with moderate and severe disease revealed that CH25H, CYP7B1 and GPR183 are significantly upregulated in macrophages during COVID-19.

CONCLUSION

This study demonstrates that oxysterols drive inflammation in the lung via GPR183 and provides the first preclinical evidence for the therapeutic benefit of targeting GPR183 during severe viral respiratory infections.

Comprehensive analysis of SARS-CoV-2 receptor proteins in human respiratory tissues identifies alveolar macrophages as potential virus entry site

AIMS

COVID-19 has had enormous consequences on global health-care and has resulted in millions of fatalities. The exact mechanism and site of SARS-CoV-2 entry into the body remains insufficiently understood. Recently, novel virus receptors were identified, and alveolar macrophages were suggested as a potential viral entry cell type and vector for intra-alveolar virus transmission. Here, we investigated the protein expression of 10 well-known and novel virus entry molecules along potential entry sites in humans using immunohistochemistry.

METHODS AND RESULTS

Samples of different anatomical sites from up to 93 patients were incorporated into tissue microarrays. Protein expression of ACE2, TMPRSS2, furin, CD147, C-type lectin receptors (CD169, CD209, CD299), neuropilin-1, ASGR1 and KREMEN1 were analysed. In lung tissues, at least one of the three receptors ACE2, ASGR1 or KREMEN1 was expressed in the majority of cases. Moreover, all the investigated molecules were found to be expressed in alveolar macrophages, and co-localisation with SARS-CoV-2 N-protein was demonstrated using dual immunohistochemistry in lung tissue from a COVID-19 autopsy. While CD169 and CD209 showed consistent protein expression in sinonasal, conjunctival and bronchiolar tissues, neuropilin-1 and ASGR1 were mostly absent, suggesting a minor relevance of these two molecules at these specific sites.

CONCLUSION

Our results extend recent discoveries indicating a role for these molecules in virus entry at different anatomical sites. Moreover, they support the notion of alveolar macrophages being a potential entry cell for SARS-CoV-2.

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.

Heterogeneity in IgG-CD16 signaling in infectious disease outcomes

In this review, we discuss how IgG antibodies can modulate inflammatory signaling during viral infections with a focus on CD16a-mediated functions. We describe the structural heterogeneity of IgG antibody ligands, including subclass and glycosylation that impact binding by and downstream activity of CD16a, as well as the heterogeneity of CD16a itself, including allele and expression density. While inflammation is a mechanism required for immune homeostasis and resolution of acute infections, we focus here on two infectious diseases that are driven by pathogenic inflammatory responses during infection. Specifically, we review and discuss the evolving body of literature showing that afucosylated IgG immune complex signaling through CD16a contributes to the overwhelming inflammatory response that is central to the pathogenesis of severe forms of dengue disease and coronavirus disease 2019 (COVID-19).

Cellular and Molecular Mechanism of Pulmonary Fibrosis Post-COVID-19: Focus on Galectin-1, -3, -8, -9

Pulmonary fibrosis is a consequence of the pathological accumulation of extracellular matrix (ECM), which finally leads to lung scarring. Although the pulmonary fibrogenesis is almost known, the last two years of the COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its post effects added new particularities which need to be explored. Many questions remain about how pulmonary fibrotic changes occur within the lungs of COVID-19 patients, and whether the changes will persist long term or are capable of resolving. This review brings together existing knowledge on both COVID-19 and pulmonary fibrosis, starting with the main key players in promoting pulmonary fibrosis, such as alveolar and endothelial cells, fibroblasts, lipofibroblasts, and macrophages. Further, we provide an overview of the main molecular mechanisms driving the fibrotic process in connection with Galactin-1, -3, -8, and -9, together with the currently approved and newly proposed clinical therapeutic solutions given for the treatment of fibrosis, based on their inhibition. The work underlines the particular pathways and processes that may be implicated in pulmonary fibrosis pathogenesis post-SARS-CoV-2 viral infection. The recent data suggest that galectin-1, -3, -8, and -9 could become valuable biomarkers for the diagnosis and prognosis of lung fibrosis post-COVID-19 and promising molecular targets for the development of new and original therapeutic tools to treat the disease.