Hypersensitivity may be involved in severe COVID-19

Area of Science:

• Immunology
• Pulmonology
• Infectious Diseases

Background:

• Severe Coronavirus Disease 2019 (COVID-19) deaths are primarily linked to hypoxemic respiratory failure.
• While the inflammatory storm is a known factor, hypersensitivity reactions may also drive severe COVID-19 pathogenesis.
• Corticosteroids (CS) show efficacy in severe COVID-19 cases, suggesting a role for hypersensitivity.

Purpose of the Study:

• To investigate the role of specific IgE antibodies against SARS-CoV-2 proteins in COVID-19.
• To correlate IgE levels with clinical severity and pulmonary function.
• To explore mast cell activation and airway hyperresponsiveness in COVID-19 patients.

Main Methods:

• Measured serum levels of anti-SARS-CoV-2 spike S1 protein-specific IgE (SP-IgE) and anti-SARS-CoV-2 nucleocapsid protein-specific IgE (NP-IgE).
• Analyzed correlations between IgE levels and clinical severity, including lung severity scores and oxygenation.
• Conducted pulmonary function tests, bronchial provocation tests, and histological analysis for mast cell activation.

Main Results:

• Significantly higher SP-IgE and NP-IgE levels were found in severe COVID-19 cases.
• IgE levels correlated with total lung severity scores and PaO2/FiO2 ratio.
• Nucleocapsid protein, IgE, and activated mast cells were detected in airway and intestinal tissues, indicating airway hyperresponsiveness (AHR) in early convalescence. Corticosteroid treatment reduced IgE levels, but they remained elevated.

Conclusions:

• Hypersensitivity, indicated by specific IgE antibodies and mast cell activation, may play a significant role in severe COVID-19.
• Airway hyperresponsiveness is present in the early convalescent phase of COVID-19.
• Further research into hypersensitivity mechanisms could inform novel therapeutic strategies for severe COVID-19.