Circulating extracellular vesicles drive innate immune dysregulation in MIS-C

Area of Science:

• Immunology
• Virology
• Pediatrics

Background:

• Multisystem inflammatory syndrome in children (MIS-C) is a severe post-SARS-CoV-2 hyperinflammatory condition affecting multiple organs.
• The precise role of extracellular vesicles (EVs) in MIS-C immunopathology is not fully understood.

Purpose of the Study:

• To compare humoral and cytokine responses in MIS-C patients versus pediatric COVID-19.
• To investigate EV-associated viral and inflammatory signatures in MIS-C and pediatric COVID-19.

Main Methods:

• Prospective cohort study classifying patients with PCR-confirmed SARS-CoV-2 infection into asymptomatic, mild/moderate, severe COVID-19, or MIS-C groups.
• Longitudinal quantification of anti-SARS-CoV-2 antibodies (Spike, RBD, nucleocapsid) using ELISA.
• Measurement of 19 cytokines via multiplex bead assays and plasma EV analysis (isolation, characterization, Spike/RBD detection, reporter cell activation, proteomics).

Main Results:

• MIS-C patients exhibited higher and sustained anti-Spike/RBD IgG responses, indicating prolonged antigen exposure.
• MIS-C displayed a unique inflammatory profile with elevated IL-17A and IL-22 compared to severe COVID-19.
• Extracellular vesicles (EVs) from MIS-C patients showed preferential IRF pathway activation and a distinct proteomic cargo enriched in innate immune pathways and neutrophil degranulation markers.

Conclusions:

• MIS-C is characterized by sustained humoral immunity, Th17-skewed cytokines, and antigen-bearing EVs with specific immunostimulatory and proteomic profiles.
• Profiling of EVs and associated pathways (IL-17, adhesion/integrin networks) holds promise for developing MIS-C biomarkers and targeted immunomodulatory therapies.