ABSTRACT
The coronavirus disease 2019 (COVID-19) pandemic threatens human species with mortality rate of roughly 2%. We can hardly predict the time of herd immunity against and end of COVID-19 with or without success of vaccine. One way to overcome the situation is to define what delineates disease severity and serves as a molecular target. The most successful analogy is found in BCR-ABL in chronic myeloid leukemia, which is the golden biomarker, and simultaneously, the most effective molecular target. We hypothesize that S100 calcium-binding protein A8 (S100A8) is one such molecule. The underlying evidence includes accumulating clinical information that S100A8 is upregulated in severe forms of COVID-19, pathological similarities of the affected lungs between COVID-19 and S100A8-induced acute respiratory distress syndrome (ARDS) model, homeostatic inflammation theory in which S100A8 is an endogenous ligand for endotoxin sensor Toll-like receptor 4/Myeloid differentiation protein-2 (TLR4/MD-2) and mediates hyper-inflammation even after elimination of endotoxin-producing extrinsic pathogens, analogous findings between COVID-19-associated ARDS and pre-metastatic lungs such as S100A8 upregulation, pulmonary recruitment of myeloid cells, increased vascular permeability, and activation coagulation cascade. A successful treatment in an animal COVID-19 model is given with a reagent capable of abrogating interaction between S100A8/S100A9 and TLR4. In this paper, we try to verify our hypothesis that S100A8 governs COVID-19-associated ARDS.
Subject(s)
COVID-19/complications , Calgranulin A/physiology , Cytokine Release Syndrome/etiology , Inflammation/etiology , Pandemics , Respiratory Distress Syndrome/etiology , SARS-CoV-2/genetics , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/physiology , Animals , Antiviral Agents/pharmacology , COVID-19/genetics , COVID-19/pathology , Calgranulin A/blood , Calgranulin A/genetics , Chemokine CXCL11/blood , Cytokine Release Syndrome/genetics , Cytokine Release Syndrome/pathology , Disaccharides/pharmacology , Disaccharides/therapeutic use , Disease Models, Animal , Drug Discovery , Epithelial Cells/metabolism , Epithelial Cells/virology , Humans , Inflammation/genetics , Inflammation/pathology , Lung/metabolism , Lung/pathology , Lung/virology , Lung Neoplasms/drug therapy , Lung Neoplasms/secondary , Lymphocyte Antigen 96/physiology , Macaca mulatta , Mice , Mice, Transgenic , Models, Biological , Mutation , Respiratory Distress Syndrome/genetics , Respiratory Distress Syndrome/metabolism , Species Specificity , Sugar Phosphates/pharmacology , Sugar Phosphates/therapeutic use , Toll-Like Receptor 4/physiology , Up-Regulation , Virus InternalizationABSTRACT
Severe cases of coronavirus disease 2019 (COVID-19) are regularly complicated by respiratory failure. Although it has been suggested that elevated levels of blood neutrophils associate with worsening oxygenation in COVID-19, it is unknown whether neutrophils are drivers of the thrombo-inflammatory storm or simple bystanders. To better understand the potential role of neutrophils in COVID-19, we measured levels of the neutrophil activation marker S100A8/A9 (calprotectin) in hospitalized patients and determined its relationship to severity of illness and respiratory status. Patients with COVID-19 (n = 172) had markedly elevated levels of calprotectin in their blood. Calprotectin tracked with other acute phase reactants including C-reactive protein, ferritin, lactate dehydrogenase, and absolute neutrophil count, but was superior in identifying patients requiring mechanical ventilation. In longitudinal samples, calprotectin rose as oxygenation worsened. When tested on day 1 or 2 of hospitalization (n = 94 patients), calprotectin levels were significantly higher in patients who progressed to severe COVID-19 requiring mechanical ventilation (8039 ± 7031 ng/ml, n = 32) as compared to those who remained free of intubation (3365 ± 3146, P < 0.0001). In summary, serum calprotectin levels track closely with current and future COVID-19 severity, implicating neutrophils as potential perpetuators of inflammation and respiratory compromise in COVID-19.
Subject(s)
COVID-19 , Calgranulin A , Calgranulin B , Neutrophil Activation , Neutrophils , SARS-CoV-2 , COVID-19/blood , COVID-19/immunology , COVID-19/pathology , COVID-19/therapy , Calgranulin A/blood , Calgranulin A/immunology , Calgranulin B/blood , Calgranulin B/immunology , Female , Hospitalization , Humans , Male , Middle Aged , Neutrophils/immunology , Neutrophils/metabolism , Neutrophils/pathology , SARS-CoV-2/immunology , SARS-CoV-2/metabolism , Severity of Illness Index , Time FactorsABSTRACT
INTRODUCTION: Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although demographic and clinical parameters such as sex, age, comorbidities, genetic background and various biomarkers have been identified as risk factors, there is an unmet need to predict the risk and onset of severe inflammatory disease leading to poor clinical outcomes. In addition, very few mechanistic biomarkers are available to inform targeted treatment of severe (auto)-inflammatory conditions associated with COVID-19. Calprotectin, also known as S100A8/S100A9, MRP8/14 (Myeloid-Related Protein) or L1, is a heterodimer involved in neutrophil-related inflammatory processes. In COVID-19 patients, calprotectin levels were reported to be associated with poor clinical outcomes such as significantly reduced survival time, especially in patients with severe pulmonary disease. AREAS COVERED: Pubmed was searched using the following keywords: Calprotectin + COVID19, S100A8/A9 + COVID19, S100A8 + COVID-19, S100A9 + COVID-19, MRP8/14 + COVID19; L1 + COVID-19 between May 2020 and 8 March 2021. The results summarized in this review provide supporting evidence and propose future directions that define calprotectin as an important biomarker in COVID-19. EXPERT OPINION: Calprotectin represents a promising serological biomarker for the risk assessment of COVID-19 patients.
Subject(s)
ATP-Binding Cassette Transporters , COVID-19 , Calgranulin A , Calgranulin B , Severity of Illness Index , ATP-Binding Cassette Transporters/blood , ATP-Binding Cassette Transporters/immunology , Biomarkers/blood , COVID-19/blood , COVID-19/immunology , Calgranulin A/blood , Calgranulin A/immunology , Calgranulin B/blood , Calgranulin B/immunology , HumansABSTRACT
Coronavirus disease 2019 (COVID-19) is associated with immune dysregulation and cytokine storm. Exploring the immune-inflammatory characteristics of COVID-19 patients is essential to reveal pathogenesis and predict progression. In this study, COVID-19 patients showed decreased CD3+, CD4+, and CD8+ T cells but increased neutrophils in circulation, exhibiting upregulated neutrophil-to-lymphocyte and neutrophil-to-CD8+ T cell ratio. IL-6, TNF-α, IL-1ß, IL-18, IL-12/IL-23p40, IL-10, Tim-3, IL-8, neutrophil extracellular trap-related proteinase 3, and S100A8/A9 were elevated, whereas IFN-γ and C-type lectin domain family 9 member A (clec9A) were decreased in COVID-19 patients compared with healthy controls. When compared with influenza patients, the expressions of TNF-α, IL-18, IL-12/IL-23p40, IL-8, S100A8/A9 and Tim-3 were significantly increased in critical COVID-19 patients, and carcinoembryonic Ag, IL-8, and S100A8/A9 could serve as clinically available hematologic indexes for identifying COVID-19 from influenza. Moreover, IL-6, IL-8, IL-1ß, TNF-α, proteinase 3, and S100A8/A9 were increased in bronchoalveolar lavage fluid of severe/critical patients compared with moderate patients, despite decreased CD4+ T cells, CD8+ T cells, B cells, and NK cells. Interestingly, bronchoalveolar IL-6, carcinoembryonic Ag, IL-8, S100A8/A9, and proteinase 3 were found to be predictive of COVID-19 severity and may serve as potential biomarkers for predicting COVID-19 progression and potential targets in therapeutic intervention of COVID-19.