Bisphosphonate-induced differential modulation of immune cell function in gingiva and bone marrowin vivo: Role in osteoclast-mediated NK cell activation

Abstract

The aim of this study is to establish osteoclasts as key immune effectors capable of activating the function of Natural Killer (NK) cells, and expanding their numbers, and to determine in vivo and in vitro effect of bisphosphonates (BPs) during NK cell interaction with osteoclasts and on systemic and local immune function. The profiles of 27 cytokines, chemokines and growth factors released from osteoclasts were found to be different from dendritic cells and M1 macrophages but resembling to untreated monocytes and M2 macrophages. Nitrogen-containing BPs Zoledronate (ZOL) and Alendronate (ALN), but not non-nitrogen-containing BPs Etidronate (ETI), triggered increased release of pro-inflammatory mediators from osteoclasts while all three BPs decreased pit formation by osteoclasts. ZOL and ALN mediated significant release of IL-6, TNF-` and IL-1β, whereas they inhibited IL-10 secretion by osteoclasts. Treatment of osteoclasts with ZOL inhibited NK cell mediated cytotoxicity whereas it induced significant secretion of cytokines and chemokines. NK cells lysed osteoclasts much more than their precursor cells monocytes, and this correlated with the decreased expression of MHC class I expression on osteoclasts. Intravenous injection of ZOL in mice induced pro-inflammatory microenvironment in bone marrow and demonstrated significant immune activation. By contrast, tooth extraction wound of gingival tissues exhibited profound immune suppressive microenvironment associated with dysregulated wound healing due to the effect of ZOL which could potentially be responsible for the pathogenesis of Osteonecrosis of the Jaw (ONJ). Finally, based on the data obtained in this paper we demonstrate that osteoclasts can be used as targets for the expansion of NK cells with superior function for immunotherapy of cancer.

Plasticity of Myeloid Cells during Oral Barrier Wound Healing and the Development of Bisphosphonate-related Osteonecrosis of the Jaw

“…The multiplex assay of cultured oral barrier cells suggested the significant reduction in secretion of cytokines and chemokines in the ZOL group at week 2 ( Fig. 2C), which was consistent with the previously reported microarraybased transcriptome assay of the mouse oral barrier tissue (50). The oral barrier microenvironment of ZOL mice may be less effective for wound healing and inflammatory resolution.…”

“…We previously reported that bisphosphonate-affected osteoclasts secreted proinflammatory cytokines (50), which appeared to locate adjacent to the osteonecrosis area (31) (Fig. 1).…”

“…tor (50). The treatment with nitrogen-containing bisphosphonates, but not with non-nitrogen-containing bisphosphonate, significantly up-regulated the synthesis of proinflammatory cytokines by osteoclasts.…”

“…The development of ONJ-like lesion occurred in the second week of tooth extraction in our ZOL-treated mouse model, characterized by the increased area of osteonecrosis interfacing the inflamed oral barrier tissue and abnormal oral epithelial hyperplasia (31,50) (Fig. 1).…”

Adoptive transfer of osteoclast-expanded natural killer cells for immunotherapy targeting cancer stem-like cells in humanized mice

“…We have previously shown that this myeloid subset is a potent activator of NK cells, and their effect on the induction of cytotoxicity and secretion of cytokines and chemokines by NK cells is much stronger than when using monocytes or DCs [62]. Human osteoclasts produce IL-15, IL-12, IL-18 and IFN-α, but not IFN-γ; they express low levels of MHC class I and II, CD14, CD11b and CD54, and they do not upregulate MHC class I surface expression when treated with either the combination of TNF-α and IFN-γ or with activated NK supernatants known to increase MHC class I expression [62]. Low expression of MHC class I together with increased release of IL-15, IL-12, IL-18 and IFN-α may be the main mechanisms by which osteoclasts are able to expand functionally potent NK cells ([62], manuscript in preparation).…”