Transcriptional profiles of the Hodgkin lymphoma tumor-associated macrophage in vitro models

Tumor-associated macrophages (TAMs) of classic Hodgkin Lymphoma (cHL) contribute to the development of immunosuppressive tumor microenvironment (TME) and are associated with worse treatment outcome. However, detailed features and functions of cHL TAMs and their therapeutic vulnerabilities remain largely unknown. To gain deeper insight into the biology of TAMs in cHL, we analyzed diagnostic biopsies by Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq) and assessed transcriptional, proteomic and metabolic profiles of the in vitro TAM models. We show that Reed-Sternberg (RS) cells of cHL induce disease-specific TAM phenotype, characterized by elevated expression of factors involved in chemotaxis, angiogenesis, extracellular matrix remodeling and tumor immune escape. Importantly, RS cell-conditioned TAMs expressed TGFβ, CCL17 and tryptophan catabolizing enzymes, IDO1 and IL4I1, facilitating induction or and/or recruitment of Tregs. In addition, we identified PIM1/2/3 kinases in cHL TAMs. We characterized PIMs as important hubs orchestrating RS-macrophage interactions. Pharmacological PIM blockade attenuated development of TAM transcriptional profile and phenotype induced by RS cells. In established TAMs, PIM inhibition or PROTAC-mediated degradation decreased expression of multiple factors associated with pro-tumoral TAM functions, including IL8, MMP9, CHI3L1/2, CD206, CD209, PD-L1, CCL17, TGFβ, IL4I1 and IDO1. PIM blockade attenuated TAM-dependent eosinophil chemoattraction, extracellular matrix remodelling, angiogenesis and regulatory T cell development. Taken together, our study highlights the role of PIMs in regulation of TAM activities involved in cHL pathogenesis and potentially relevant for response of cHL patients to immunotherapies.