Lymphatic malformations (LMs) are congenital vascular anomalies characterized by abnormal lymphatic development, leading to disfigurement and severe clinical complications. However, the immunopathological mechanisms underlying LMs remain poorly defined. Here, we provide a comprehensive single-cell immune landscape of LMs by integrating single-cell RNA, T-cell receptor, and B-cell receptor sequencing (scRNA-seq, scTCR-seq, and scBCR-seq) on peripheral blood and pleural effusion samples, uncovering profound immune dysregulation and chronic inflammation.
We identified a marked expansion of pro-inflammatory CD14⁺CD16⁺ monocytes and atypical memory B cells, alongside a reduction in cytotoxic GZMB⁺ CD8⁺ T cells and CD16⁺ NK cells. CD14⁺ monocytes exhibited impaired antigen processing and presentation, associated with reduced activity of transcription factors (TFs) REL and RFX5. Clonotype profiling uncovered increased clonality and decreased diversity of TCR and BCR repertoires, indicating immune exhaustion. Additionally, transcriptional dysregulation disrupted the effector differentiation trajectories of CD8⁺ T cells and NK cells in LMs, leading to impaired cytotoxic function and diminished immune surveillance. Furthermore, intercellular communication analysis highlighted the involvement of the CXCL16-CXCR6 axis in promoting inflammation and the upregulation of the inhibitory checkpoint HLA-E:CD94-NKG2A, potentially contributing to NK cell dysfunction.
A critical discovery was the identification of a Shared CD14⁺CD16⁺ Monocyte Expression Program (SMEP), a conserved pro-inflammatory transcriptional signature across blood and pleural effusion. Through drug-gene interaction screening, S100A8 was pinpointed as a key druggable target within the SMEP. Importantly, pharmacological inhibition of S100A8 with paquinimod significantly ameliorated lymphatic malformation phenotypes in a Vegfr3^+/- mouse model, validating its therapeutic potential.
In conclusion, this study delineates the cellular and molecular immune dysregulation underlying LMs, revealing key mechanistic insights into the coordinated inflammatory signaling and impaired cytotoxic immunity. It identifies specific transcription factors, immune checkpoints, and the S100A8 inhibitor paquinimod as promising biomarkers and therapeutic avenues for this debilitating disease.
DOI：10.1093/procel/pwaf103