VISTA drives macrophages towards a pro-tumoral phenotype that promotes cancer cell phagocytosis yet down-regulates T cell responses

• Published in: Experimental hematology & oncology Vol. 13; no. 1; p. 35
• Main Authors: Lin, Yusheng, Choukrani, Ghizlane, Dubbel, Lena, Rockstein, Lena, Freile, Jimena Alvarez, Qi, Yuzhu, Wiersma, Valerie, Zhang, Hao, Koch, Karl-Wilhelm, Ammatuna, Emanuele, Schuringa, Jan Jacob, van Meerten, Tom, Huls, Gerwin, Bremer, Edwin
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 29.03.2024; BioMed Central; BMC
• Subjects: Analysis; Antigens; B cells; Cancer; Care and treatment; Cells; Cytokines; Enzyme-linked immunosorbent assay; Enzymes; Gene expression; Genes; Genetic aspects; Genotype & phenotype; Immune checkpoint; Innate immunity; Ligands; Lymphocytes; Lymphoma; Macrophage biology; Macrophages; Morphology; Non-Hodgkin's lymphomas; Phagocytosis; T cells; VISTA; Netherlands; Innate immunity; Immune checkpoint; VISTA; Macrophage biology; Phagocytosis
• ISSN: 2162-3619; 2162-3619
• DOI: 10.1186/s40164-024-00501-x

VISTA is a well-known immune checkpoint in T cell biology, but its role in innate immunity is less established. Here, we investigated the role of VISTA on anticancer macrophage immunity, with a focus on phagocytosis, macrophage polarization and concomitant T cell activation. Macrophages, differentiated from VISTA overexpressed THP-1 cells and cord blood CD34 cell-derived monocytes, were used in phagocytosis assay using B lymphoma target cells opsonized with Rituximab. PBMC-derived macrophages were used to assess the correlation between phagocytosis and VISTA expression. qRT-PCR, flow cytometry, and enzyme-linked immunosorbent assay were performed to analyze the impact of VISTA on other checkpoints and M1/M2-like macrophage biology. Additionally, flow cytometry was used to assess the frequency of CD14 monocytes expressing VISTA in PBMCs from 65 lymphoma patients and 37 healthy donors. Ectopic expression of VISTA in the monocytic model cell line THP-1 or in primary monocytes triggered differentiation towards the macrophage lineage, with a marked increase in M2-like macrophage-related gene expression and decrease in M1-like macrophage-related gene expression. VISTA expression in THP-1 and monocyte-derived macrophages strongly downregulated expression of SIRPα, a prominent 'don't eat me' signal, and augmented phagocytic activity of macrophages against cancer cells. Intriguingly, expression of VISTA's extracellular domain alone sufficed to trigger phagocytosis in ∼ 50% of cell lines, with those cell lines also directly binding to recombinant human VISTA, indicating ligand-dependent and -independent mechanisms. Endogenous VISTA expression was predominantly higher in M2-like macrophages compared to M0- or M1-like macrophages, with a positive correlation observed between VISTA expression in M2c macrophages and their phagocytic activity. VISTA-expressing macrophages demonstrated a unique cytokine profile, characterized by reduced IL-1β and elevated IL-10 secretion. Furthermore, VISTA interacted with MHC-I and downregulated its surface expression, leading to diminished T cell activation. Notably, VISTA surface expression was identified in monocytes from all lymphoma patients but was less prevalent in healthy donors. Collectively, VISTA expression associates with and drives M2-like activation of macrophages with a high phagocytic capacity yet a decrease in antigen presentation capability to T cells. Therefore, VISTA is a negative immune checkpoint regulator in macrophage-mediated immune suppression.