ABSTRACT
BACKGROUND: Deaths attributed to Coronavirus Disease 2019 (COVID-19) are mainly due to severe hypoxemic respiratory failure. Although the inflammatory storm has been considered the main pathogenesis of severe COVID-19, hypersensitivity may be another important mechanism involved in severe cases, which have a perfect response to corticosteroids (CS). METHOD: We detected the serum level of anti-SARS-CoV-2-spike S1 protein-specific IgE (SP-IgE) and anti-SARS-CoV-2 nucleocapsid protein-specific IgE (NP-IgE) in COVID-19. Correlation of levels of specific IgE and clinical severity were analysed. Pulmonary function test and bronchial provocation test were conducted in early convalescence of COVID-19. We also obtained histological samples via endoscopy to detect the evidence of mast cell activation. RESULT: The levels of serum SP-IgE and NP-IgE were significantly higher in severe cases, and were correlated with the total lung severity scores (TLSS) and the PaO2 /FiO2 ratio. Nucleocapsid protein could be detected in both airway and intestinal tissues, which was stained positive together with activated mast cells, binded with IgE. Airway hyperresponsiveness (AHR) exists in the early convalescence of COVID-19. After the application of CS in severe COVID-19, SP-IgE and NP-IgE decreased, but maintained at a high level. CONCLUSION: Hypersensitivity may be involved in severe COVID-19.
Subject(s)
Bronchi/immunology , COVID-19/immunology , Coronavirus Nucleocapsid Proteins/immunology , Duodenum/immunology , Hypersensitivity/immunology , Immunoglobulin E/immunology , Mast Cells/immunology , Spike Glycoprotein, Coronavirus/immunology , Adolescent , Adult , Aged , Aged, 80 and over , Bronchi/metabolism , Bronchi/pathology , COVID-19/metabolism , COVID-19/pathology , COVID-19/physiopathology , Case-Control Studies , Coronavirus Nucleocapsid Proteins/metabolism , Duodenum/metabolism , Duodenum/pathology , Female , Humans , Hypersensitivity/metabolism , Hypersensitivity/pathology , Hypersensitivity/physiopathology , Lung/physiopathology , Male , Mast Cells/metabolism , Mast Cells/pathology , Middle Aged , Mucous Membrane/immunology , Mucous Membrane/metabolism , Mucous Membrane/pathology , Phosphoproteins/immunology , Phosphoproteins/metabolism , Recovery of Function , Respiratory Hypersensitivity/physiopathology , Retrospective Studies , SARS-CoV-2 , Severity of Illness Index , Spike Glycoprotein, Coronavirus/metabolism , Young AdultABSTRACT
The SARS-CoV-2 pandemic has so far claimed over three and a half million lives worldwide. Though the SARS-CoV-2 mediated disease COVID-19 has first been characterized by an infection of the upper airways and the lung, recent evidence suggests a complex disease including gastrointestinal symptoms. Even if a direct viral tropism of intestinal cells has recently been demonstrated, it remains unclear, whether gastrointestinal symptoms are caused by direct infection of the gastrointestinal tract by SARS-CoV-2 or whether they are a consequence of a systemic immune activation and subsequent modulation of the mucosal immune system. To better understand the cause of intestinal symptoms we analyzed biopsies of the small intestine from SARS-CoV-2 infected individuals. Applying qRT-PCR and immunohistochemistry, we detected SARS-CoV-2 RNA and nucleocapsid protein in duodenal mucosa. In addition, applying imaging mass cytometry and immunohistochemistry, we identified histomorphological changes of the epithelium, which were characterized by an accumulation of activated intraepithelial CD8+ T cells as well as epithelial apoptosis and subsequent regenerative proliferation in the small intestine of COVID-19 patients. In summary, our findings indicate that intraepithelial CD8+ T cells are activated upon infection of intestinal epithelial cells with SARS-CoV-2, providing one possible explanation for gastrointestinal symptoms associated with COVID-19.