Single-cell profiling reveals the importance of CXCL13/CXCR5 axis biology in lymphocyte-rich classic Hodgkin lymphoma
Menée à partir du séquençage, à l'échelle de la cellule, de l'ARN d'échantillons tissulaires prélevés sur des patients atteints d'un lymphome hodgkinien, cette étude examine les caractéristiques fonctionnelles et spatiales des cellules immunitaires du microenvironnement des lymphomes hodgkiniens riches en lymphocytes puis met en évidence l'importance du ligand CXCL13 et du récepteur CXCR5 dans le caractère pathogène de la maladie
Our study provides detailed functional and spatial characteristics of immune cells in the LR-CHL microenvironment at single-cell resolution. We describe detailed T cell subset definitions and importantly identified a unique CD4+PD-1+CXCL13+CXCR5− TFH-like subset that surrounds HRS cells, appears in close proximity to CXCR5+ B cells, and is associated with poor clinical outcome. We also uncovered unique PD-1/PD-L1 axis biology in LR-CHL, namely a negative correlation between PD-L1 genetic alterations on HRS cells and PD-1 protein expression in the tumor microenvironment. Importantly, our findings contribute to a deeper understanding of cellular cross-talk in LR-CHL, which may aid in the development of novel biomarkers and targeted treatment strategies.Lymphocyte-rich classic Hodgkin lymphoma (LR-CHL) is a rare subtype of Hodgkin lymphoma. Recent technical advances have allowed for the characterization of specific cross-talk mechanisms between malignant Hodgkin Reed-Sternberg (HRS) cells and different normal immune cells in the tumor microenvironment (TME) of CHL. However, the TME of LR-CHL has not yet been characterized at single-cell resolution. Here, using single-cell RNA sequencing (scRNA-seq), we examined the immune cell profile of 8 cell suspension samples of LR-CHL in comparison to 20 samples of the mixed cellularity (MC, 9 cases) and nodular sclerosis (NS, 11 cases) subtypes of CHL, as well as 5 reactive lymph node controls. We also performed multicolor immunofluorescence (MC-IF) on tissue microarrays from the same patients and an independent validation cohort of 31 pretreatment LR-CHL samples. ScRNA-seq analysis identified a unique CD4+ helper T cell subset in LR-CHL characterized by high expression of Chemokine C-X-C motif ligand 13 (CXCL13) and PD-1. PD-1+CXCL13+ T cells were significantly enriched in LR-CHL compared to other CHL subtypes, and spatial analyses revealed that in 46% of the LR-CHL cases these cells formed rosettes surrounding HRS cells. MC-IF analysis revealed CXCR5+ normal B cells in close proximity to CXCL13+ T cells at significantly higher levels in LR-CHL. Moreover, the abundance of PD-1+CXCL13+ T cells in the TME was significantly associated with shorter progression-free survival in LR-CHL (P = 0.032). Taken together, our findings strongly suggest the pathogenic importance of the CXCL13/CXCR5 axis and PD-1+CXCL13+ T cells as a treatment target in LR-CHL.Single cell RNA-seq counts (generated with CellRanger v2.1.0) and a merged ‘SingleCellExperiment’ R object is available in the European Genome-phenome Archive (EGA) (EGAS00001005541) via controlled access.
Proceedings of the National Academy of Sciences , article en libre accès, 2020