MAIT cell activation and dynamics associated with COVID-19 disease severity

Area of Science:

• Immunology
• Virology
• Respiratory Medicine

Background:

• Severe COVID-19 involves excessive airway inflammation, with immune response balance poorly understood.
• Mucosa-associated invariant T (MAIT) cells are T cells recognizing bacterial metabolites and mediating antiviral responses.

Purpose of the Study:

• To investigate the role and dynamics of MAIT cells in COVID-19 patients with moderate and severe disease.
• To explore MAIT cell involvement in SARS-CoV-2 immunopathogenesis.

Main Methods:

• Analysis of MAIT cell populations in circulation and airways of COVID-19 patients.
• Transcriptomic analysis to identify MAIT cell characteristics and airway enrichment.
• Correlation of MAIT cell immunotypes with clinical outcomes.

Main Results:

• Profound decline and activation of circulating MAIT cells in active COVID-19.
• Enrichment of MAIT cells with a pro-inflammatory IL-17A bias in the airways.
• Identification of MAIT cell immunotypes (CD69high, CXCR3low) linked to poor clinical outcomes.
• Normalization of MAIT cell levels during convalescence.

Conclusions:

• MAIT cells are dynamically recruited to tissues during SARS-CoV-2 infection and return to circulation upon resolution.
• MAIT cells are significantly engaged in the immune response to SARS-CoV-2.
• MAIT cells may play a role in the immunopathogenesis of COVID-19.