RESUMO
iPA is a naturally occurring nucleoside with an isopentenyl moiety derived from the mevalonate pathway and a well-established anti-tumor activity. In analogy to the unique specificity for phosphoantigens, such as IPP, shown by human Vγ9Vδ2 T cells, here, we report for the first time the ability of iPA to selectively expand and directly target human NK cells. Interestingly, submicromolar doses of iPA stimulate resting human NK cells and synergize with IL-2 to induce a robust activation ex vivo with significant secretion of CCL5 and CCL3 and a large increase in TNF-α and IFN-γ production when compared with IL-2 single cytokine treatment. Moreover, iPA promotes NK cell proliferation and up-regulates the expression of specific NK cell-activating receptors, as well as CD69 and CD107a expression. Accordingly, this phenotype correlates with significantly greater cytotoxicity against tumor targets. At the molecular level, iPA leads to a selective, potent activation of MAPK signaling intermediaries downstream of the IL-2R. The effect results, at least in part, from the fine modulation of the FDPS activity, the same enzyme implicated in the stimulation of the human γδ T cells. The iPA-driven modulation of FDPS can cause an enhancement of post-translational prenylation essential for the biological activity of key proteins in NK signaling and effector functions, such as Ras. These unanticipated properties of iPA provide an additional piece of evidence of the immunoregulatory role of the intermediates of the mevalonate pathway and open novel therapeutic perspectives for this molecule as an immune-modulatory drug.
Assuntos
Geraniltranstransferase/imunologia , Imunidade Celular/fisiologia , Isopenteniladenosina/imunologia , Células Matadoras Naturais/imunologia , Sistema de Sinalização das MAP Quinases/fisiologia , Antígenos CD/imunologia , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/imunologia , Antígenos de Diferenciação de Linfócitos T/metabolismo , Quimiocina CCL3/biossíntese , Quimiocina CCL3/imunologia , Quimiocina CCL5/biossíntese , Quimiocina CCL5/imunologia , Feminino , Regulação da Expressão Gênica/fisiologia , Geraniltranstransferase/metabolismo , Humanos , Fatores Imunológicos/imunologia , Fatores Imunológicos/farmacologia , Interferon gama/biossíntese , Interferon gama/imunologia , Interleucina-2/imunologia , Isopenteniladenosina/metabolismo , Isopenteniladenosina/farmacologia , Células K562 , Células Matadoras Naturais/citologia , Células Matadoras Naturais/enzimologia , Lectinas Tipo C/imunologia , Lectinas Tipo C/metabolismo , Proteína 1 de Membrana Associada ao Lisossomo/imunologia , Proteína 1 de Membrana Associada ao Lisossomo/metabolismo , Masculino , Reguladores de Crescimento de Plantas/imunologia , Reguladores de Crescimento de Plantas/farmacologia , Prenilação de Proteína/fisiologia , Receptores de Antígenos de Linfócitos T gama-delta , Terpenos/imunologia , Terpenos/metabolismo , Fator de Necrose Tumoral alfa/biossíntese , Fator de Necrose Tumoral alfa/imunologiaRESUMO
Exposing human tumor cells to nitrogen-containing bisphosphonates, such as zoledronic acid (Zol), greatly increases their susceptibility to killing by γδ T cells. Based on this finding and other studies, cancer immunotherapy using γδ T cells and nitrogen-containing bisphosphonates has been studied in pilot clinical trials and has shown benefits. Although Zol treatment can render a wide variety of human tumor cells susceptible to γδ T cell killing, there has not been a systematic investigation to determine which types of tumor cells are the most susceptible to γδ T cell-mediated cytotoxicity. In this study, we determined the Zol concentrations required to stimulate half maximal tumor necrosis factor-α production by γδ T cells cultured with various tumor cell lines pretreated with Zol and compared these concentrations with those required for half maximal inhibition of farnesyl diphosphate synthase (FPPS) in the same tumor cell lines. The inhibition of tumor cell growth by Zol was also assessed. We found that FPPS inhibition strongly correlated with γδ T cell activation, confirming that the mechanism underlying γδ T cell activation by Zol is isopentenyl diphosphate (IPP) accumulation due to FPPS blockade. In addition, we showed that γδ T-cell receptor-mediated signaling correlated with γδ T cell tumor necrosis factor-α production and cytotoxicity. Some lymphoma, myeloid leukemia, and mammary carcinoma cell lines were relatively resistant to Zol treatment, suggesting that assessing tumor sensitivity to Zol may help select those patients most likely to benefit from immunotherapy with γδ T cells.
Assuntos
Difosfonatos/farmacologia , Geraniltranstransferase/antagonistas & inibidores , Imidazóis/farmacologia , Leucemia Mieloide/tratamento farmacológico , Linfoma/tratamento farmacológico , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , Linfócitos T/efeitos dos fármacos , Linhagem Celular Tumoral , Citotoxicidade Imunológica/efeitos dos fármacos , Citotoxicidade Imunológica/imunologia , Difosfonatos/imunologia , Geraniltranstransferase/imunologia , Geraniltranstransferase/metabolismo , Células HL-60 , Hemiterpenos/imunologia , Hemiterpenos/metabolismo , Humanos , Imidazóis/imunologia , Células K562 , Leucemia Mieloide/imunologia , Leucemia Mieloide/metabolismo , Linfoma/imunologia , Linfoma/metabolismo , Células MCF-7 , Compostos Organofosforados/imunologia , Compostos Organofosforados/metabolismo , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Linfócitos T/imunologia , Fator de Necrose Tumoral alfa/imunologia , Fator de Necrose Tumoral alfa/metabolismo , Células U937 , Ácido ZoledrônicoRESUMO
The pathogenesis of juvenile idiopathic arthritis (JIA) is thought to involve multiple components of the cellular immune system, including subsets of γδ T cells. In this study, we conducted experiments to define the functional roles of one of the major synovial fluid (SF) T cell subsets, Vγ9(+)Vδ2(+) (Vγ9(+)) T cells, in JIA. We found that as opposed to CD4(+) T cells, equally high percentages (â¼35%) of Vγ9(+) T cells in SF and peripheral blood (PB) produced TNF-α and IFN-γ. Furthermore, stimulation with isopentenyl pyrophosphate (IPP), a metabolite in the mevalonate pathway, which is a specific potent Ag for Vγ9Jγ1.2(+) T cells, similarly amplified cytokine secretion by SF and PB Vγ9(+) T cells. Significantly, the SF subset expressed higher levels of CD69 in situ, suggesting their recent activation. Furthermore, 24-h coculturing with SF-derived fibroblasts enhanced CD69 on the SF > PB Vγ9(+) T cells, a phenomenon strongly augmented by zoledronate, a farnesyl pyrophosphate synthase inhibitor that increases endogenous intracellular IPP. Importantly, although Vγ9(+) T cell proliferation in response to IPP was significantly lower in SF than PBMC cultures, it could be enhanced by depleting SF CD4(+)CD25(+)FOXP3(+) cells (regulatory T cells). Furthermore, coculture with the Vγ9(+) T cells in medium containing zoledronate or IPP strongly increased SF-derived fibroblasts' apoptosis. The findings that IPP-responsive proinflammatory synovial Vγ9(+) T cells for which proliferation is partly controlled by regulatory T cells can recognize and become activated by SF fibroblasts and then induce their apoptosis suggest their crucial role in the pathogenesis and control of synovial inflammation.