Single-cell transcriptomics reveal heat shock protein dysregulation in severe SARS-CoV-2-associated pediatric encephalopathy.

Severe acute encephalopathy/encephalitis (AE) associated with SARS-CoV-2 has been increasingly reported since the emergence of the Omicron variant. Several pediatric cases have shown the development of acute fulminant cerebral edema (AFCE) or hemorrhagic shock encephalopathy syndrome (HSES), which are linked to high morbidity and mortality. However, the underlying pathogenic mechanisms remain unclear. We performed single-cell RNA sequencing of peripheral blood mononuclear cells from a pediatric patient with SARS-CoV-2-associated AE presenting with AFCE/HSES and compared the data with those from two patients with mild AE, one patient with febrile seizures due to non-SARS-CoV-2 pathogens, and publicly available pediatric COVID-19 datasets without neurological complications. During the acute phase, we observed a prominent expansion of B-cell populations, including distinct activated B-cell clusters. Cell-cell communication analysis identified macrophage migration inhibitory factor signaling, although it was not specific to SARS-CoV-2-associated AE. Notably, heat shock protein genes, particularly HSPA1A and HSPB1, were selectively upregulated across multiple immune cell types only in severe SARS-CoV-2-associated AE. Enzyme-linked immunosorbent assay confirmed significantly elevated plasma and serum protein levels of HSPA1A and HSPB1 during the acute phase. These findings highlight HSPA1A and HSPB1 as potential biomarkers of severe SARS-CoV-2-associated AE and suggest a pathogenic possible role for stress-response pathways.