scRNA-seq reveals the landscape of immune repertoire of PBMNCs in iMCD.

The etiology of idiopathic multicentric Castleman disease (iMCD) is poorly understood, and the identification of targetable disease mediators remains an unmet clinical need. Thus, we firstly employed single-cell RNA sequencing (scRNA-seq) to elucidate the landscape of the immune repertoire of peripheral blood mononuclear cells (PBMNCs) in iMCD and to identify additional driver cytokines/cells/pathways to address IL-6 blockade-refractory cases. We revealed that the inflammatory cytokine storm observed in iMCD was a significant phenomenon pervasive across all immune cells. B-plasma cell subsets was the main source of IL-6. The IL-6 signaling pathway was significantly activated across a spectrum of immune cells. Systemic upregulation of CXCL13 is mainly driven by peripheral helper T (Tph) and regulatory T (Treg) cells. Notably, a significant positive interaction was observed between CXCL13-expressing T cells and IL-6 signaling-activated B cells. This study provides an immune perspective on PBMNCs in iMCD at the single-cell level, unveiling pathways or targets characterized by atypical inflammatory expression that could potentially serve as promising candidates for therapeutic intervention in iMCD.