Multidimensional single-cell analysis reveals immune dysfunction and inflammatory response in Lymphatic malformations

Abstract Lymphatic malformations (LMs) are debilitating and potentially life-threatening diseases. However, the immune phenotype of circulating cells and underlying molecular mechanisms in LMs remain poorly understood. Here, we performed integrated single-cell RNA, T-cell receptor, and B-cell receptor sequencing (scRNA-seq, scTCR-seq, and scBCR-seq) of peripheral blood and pleural effusion from patients with LMs to delineate their immune landscape. We identified an expansion of pro-inflammatory CD14+CD16+ monocytes and atypical memory B cells, accompanied by reduced cytotoxic CD8+ T and NK cells. Functional analysis revealed impaired antigen processing and presentation in CD14+ monocytes, and dysregulated transcription factor activity, potentially driving immune dysfunction. Additionally, LMs exhibited substantial remodeling of TCR and BCR repertoires, with shifts in clonality and diversity. Moreover, the CXCL16–CXCR6 interaction was associated with inflammatory responses, while upregulation of the inhibitory checkpoint HLA-E: CD94-NKG2A potentially contributed to impaired NK cell activity. Finally, we constructed a shared pro-inflammatory monocyte program and revealed S100A8 as a potential therapeutic target for LMs. We further demonstrated that S100A8 pharmacological inhibition could ameliorate the pathological lymphatic malformation phenotype. Collectively, our findings delineate cell type-specific immune dysregulation in LMs, offering insights for therapeutic development.