Transcriptomic landscape of circulating mononuclear phagocytes in Langerhans cell histiocytosis at the single-cell
1State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing, China.
Insights
Langerhans cell histiocytosis (LCH) involves MAPK pathway activation. Single-cell analysis reveals key gene expression changes in myeloid cells, offering insights for improved LCH diagnostics and treatments.
Area of Science:
- Immunology
- Oncology
- Molecular Biology
Background:
- Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm driven by aberrant mitogen-activated protein kinase (MAPK) pathway activation.
- Detailed immune-phenotypic and molecular profiles of circulating myeloid cells in LCH patients are lacking.
- Understanding these profiles can provide crucial insights into LCH disease biology.
Purpose of the Study:
- To investigate the immune-phenotypic and molecular characteristics of circulating myeloid cells in pediatric LCH patients.
- To identify molecular alterations associated with the BRAFV600E mutation in LCH.
- To evaluate the effects of BRAF inhibitor treatment on MAPK signaling and cellular metabolism in LCH.
Main Methods:
- Recruitment of 217 pediatric LCH patients for sample collection and BRAFV600E analysis.
- Immune-phenotyping of circulating Lin-HLA-DR+ immune cells in 49 patients.
- Single-cell RNA sequencing of samples from 14 patients to analyze gene expression profiles.
- Analysis of RAS-MAPK-ERK signaling-related genes and transcription factors.
Main Results:
- Decreased frequency of plasmacytoid dendritic cells correlated significantly with LCH disease severity.
- Single-cell RNA sequencing identified key changes in RAS-MAPK-ERK signaling genes and transcription factors in mononuclear phagocytes.
- Treatment with dabrafenib inhibited the MAPK cascade, reduced inflammation, and modulated mononuclear phagocyte metabolism.
- Elevated RAS-MAPK-ERK signaling genes were observed in CD207+CD1a+ cells in skin lesions.
Conclusions:
- This study provides a single-cell resolution molecular understanding of LCH biology.
- Findings highlight the role of MAPK pathway dysregulation in LCH pathogenesis.
- The results may aid in improving clinical diagnostics, therapeutics, and personalized medicine for LCH.
Abstract:
Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm caused by aberrant activation of the mitogen-activated protein kinase (MAPK) pathway. Circulating myeloid cells from patients often carry disease-associated mutations and can be differentiated into langerinhigh LCH-like cells in vitro, but their detailed immune-phenotypic and molecular profiles are lacking and could shed key insights into disease biology. Here we recruited 217 pediatric LCH patients and took blood and tissue samples for BRAFV600E analysis. Immune-phenotyping of the circulating Lin-HLA-DR+ immune population in 49 of these patients revealed that decreased frequency of plasmacytoid dendritic cells was significantly linked to disease severity. By single-cell RNA sequencing of samples from 14 patients, we identified key changes in expression of RAS-MAPK-extracellular signal-regulated kinase (ERK) signaling-related genes and transcription factors in distinct members of the mononuclear phagocyte system in the presence of BRAFV600E. Moreover, treatment of patients with the BRAF inhibitor dabrafenib resulted in MAPK cascade inhibition, inflammation prevention, and regulation of cellular metabolism within mononuclear phagocytes. Finally, we also observed elevated expression of RAS-MAPK-ERK signaling-related genes in a CD207+CD1a+ cell subcluster in skin. Taken together, our data extend the molecular understanding of LCH biology at single-cell resolution, which might contribute to improvement of clinical diagnostics and therapeutics, and aid in the development of personalized medicine approaches.
