Single-Cell RNA Sequencing Analysis Unveils Highly Active Yet Diminished CD14+CD16- Circulating Monocytes, Independent of Alopecia Areata Severity

This study investigates the role of circulating monocytes in Alopecia Areata (AA) using single-cell RNA sequencing of peripheral blood mononuclear cells from individuals with mild and severe AA, as well as healthy controls. The analysis reveals a significant depletion of highly active CD14+CD16- monocytes in AA patients, regardless of disease severity, compared to healthy controls. Despite their reduced numbers, these monocytes exhibit heightened metabolic activity and diverse immune responses, including enriched pathways for TLR signaling and interferon-gamma-mediated signaling. The study highlights the paradoxical nature of these monocytes, suggesting their pivotal role in systemic inflammation and potential as therapeutic targets in AA pathogenesis.