Zoledronic acid renders human M1 and M2 macrophages susceptible to Vδ2+ γδ T cell cytotoxicity in a perforin-dependent manner

Abstract

Vδ2+ T cells are a subpopulation of γδ T cells in humans that are cytotoxic towards cells which accumulate isopentenyl pyrophosphate. The nitrogen-containing bisphosphonate, zoledronic acid (ZA), can induce tumour cell lines to accumulate isopentenyl pyrophosphate, thus rendering them more susceptible to Vδ2+ T cell cytotoxicity. However, little is known about whether ZA renders other, non-malignant cell types susceptible. In this study we focussed on macrophages (Mϕs), as these cells have been shown to take up ZA. We differentiated peripheral blood monocytes from healthy donors into Mϕs and then treated them with IFN-γ or IL-4 to generate M1 and M2 Mϕs, respectively. We characterised these Mϕs based on their phenotype and cytokine production and then tested whether ZA rendered them susceptible to Vδ2+ T cell cytotoxicity. Consistent with the literature, IFN-γ-treated Mϕs expressed higher levels of the M1 markers CD64 and IL-12p70, whereas IL-4-treated Mϕs expressed higher levels of the M2 markers CD206 and chemokine (C–C motif) ligand 18. When treated with ZA, both M1 and M2 Mϕs became susceptible to Vδ2+ T cell cytotoxicity. Vδ2+ T cells expressed perforin and degranulated in response to ZA-treated Mϕs as shown by mobilisation of CD107a and CD107b to the cell surface. Furthermore, cytotoxicity towards ZA-treated Mϕs was sensitive—at least in part—to the perforin inhibitor concanamycin A. These findings suggest that ZA can render M1 and M2 Mϕs susceptible to Vδ2+ T cell cytotoxicity in a perforin-dependent manner, which has important implications regarding the use of ZA in cancer immunotherapy.Electronic supplementary materialThe online version of this article (doi:10.1007/s00262-017-2011-1) contains supplementary material, which is available to authorized users.

Zoledronic acid promotes TLR‐4‐mediated M1 macrophage polarization in bisphosphonate‐related osteonecrosis of the jaw

“…Considering the complex oral environment in mice, M2 macrophages could be affected by other cells, such as mesenchymal stem cells (38, 39) and tissue‐resident macrophages (37). Moreover, even human peripheral blood‐derived macrophage phenotypes were not altered by the ZA treatment (40), which indicated that the environment where the macrophages exist could also mediate cell polarization (37, 41). Nevertheless, in this study, we demonstrate that ZA‐induced M1 macrophage polarization was attributed at least partly to TLR‐4 signaling activation, but whether TLR‐4 participates in M2 polarization needs to be further investigated.…”

Oestrogen and zoledronic acid driven changes to the bone and immune environments: Potential mechanisms underlying the differential anti-tumour effects of zoledronic acid in pre- and post-menopausal conditions

“…Human monocytes were differentiated into either anti-tumour macrophages or TAMs before being treated with ZOL in vitro . ZOL treatment rendered the macrophages susceptible to γδ T cell cytotoxicity in a perforin dependent manner, independently of macrophage polarisation [89] . This could go some way to explaining a mechanism whereby TAMs are cleared from the tumour microenvironment.…”

Improving the Efficiency of Vγ9Vδ2 T-Cell Immunotherapy in Cancer

“…It is established that monocytes/macrophage type cells take up N-BPs via fluid endocytosis and induce activation of Vγ9Vδ2 T-cells ( 129 , 130 ). Unfortunately ZOL also induces killing of human macrophages ( 131 ) and, additionally, uptake of N-BP by neutrophils impairs γδ T-cell proliferation via production of reactive oxygen species ( 132 ). Indeed treatment with N-BP can decrease circulating γδ T-cell count ( 133 ) and repetitive stimulation with BrHPP lead to progressive exhaustion of γδ T-cell activation and expansion in vivo ( 22 ).…”