Single-cell profiling identifies clinically relevant interactions between tumor associated macrophages and blood endothelial cells in diffuse large B cell lymphoma

Abstract

Diffuse large B cell lymphoma (DLBCL) and follicular lymphoma (FL) are the two most common B-cell lymphomas and are characterized by a dynamic crosstalk between tumor B cells and a heterogeneous tumor-supportive microenvironment, including immune, endothelial, and stromal components. Although their impact on the pathogenesis and prognosis of B-cell lymphoma has been acknowledged for years, tumor-associated macrophages (TAM) have not been extensively explored in DLBCL and FL. Herein, we investigate mononuclear phagocytes (MNP) heterogeneity at the single cell level and their potential co-regulation with the stromal and endothelial compartments in B-cell lymphoma lymph nodes compared to reactive secondary lymphoid organs, using a combination of mass cytometry, single cell RNA sequencing, and in silico approaches. We reveal a co-regulation between TAM and blood endothelial cells (BEC) in lymphoma. Moreover, we identify a specific interaction between Annexin A1 (ANXA1)-expressing BEC and formyl-peptide receptors (FPR1/2)-expressing monocytes/macrophages in DLBCL, which we confirm in situ by multiplex immunofluorescence and imaging mass cytometry. This crosstalk is associated to an immunosuppressive tumor microenvironment and an adverse prognosis in DLBCL.

Characterization of Human B Cell Hematological Malignancies Using Protein-Based Approaches

“…Assessment of the healthy B cell pool of patients to find disease mechanisms [128] DLBCL Evaluation of the intertumoral and intratumoral heterogeneity [129] Identification of clinically relevant interactions between tumor-associated macrophages and blood endothelial cells [130] Finding proteins overexpressed in relapsed and refractory patients [131] Comparison of major immune subsets in DLBCL and double-hit lymphoma [132] Identification of differences in immune cell compartments across various stages of MM and healthy individuals [133] Description of the immune tumor microenvironment in patients with MGUS and MM at diagnosis and post-initial therapies [134] Analysis of the immune checkpoint signature and regulation [135] Characterization of NK cells in newly diagnosed cases [136] Understanding of the molecular and cellular complexities underlying disease heterogeneity and prognosis [137] Provision of insights into the mechanism of action of daratumumab and the anti-PD-L1 monoclonal antibody atezolizumab [138] MM Employment of protein profiling as a tool for prognosis and treatment stratification [139] Other Tools RRPA CLL Prediction of survival outcomes based on the proteomic signature [140] Protein Microarrays FL Identification of antibodies that distinguish lymphoid follicles in FL and benign follicular hyperplasia [141] MCL Monitoring of patient serum proteomes to identify treatment-modulated proteins linked to the presence of minimal residual disease [142] Western Blot MCL Definition of the pathologic hallmark of MCL as a tool for the diagnosis [143] araCTP, Next, we describe the basis of the main protein-based strategies employed for studying B cell malignancies.…”

“…Other myeloid cells not extensively investigated in DLBCL disease are the tumor-associated macrophages (TAM). Using mass cytometry, Ferrant et al [130] reported a co-regulation between TAMs and the activation status of blood endothelial cells in lymphoma via an alteration of the annexin A1 and the formyl-peptide receptor axis.…”