Monocytes and γδ T cells control the acute-phase response to intravenous zoledronate: insights from a phase IV safety trial

Correlations between Immune Response and Etiopathogenic Factors of Medication-Related Osteonecrosis of the Jaw in Cancer Patients Treated with Zoledronic Acid

Impairment of the immune response in MRONJ (medication-related osteonecrosis of the jaws) is one of the still unclear etiopathogenic mechanisms of this condition encountered in cancer patients treated with bisphosphonates, with negative effects on the patient's quality of life. The aim of the present study was to correlate the immune response with etiopathogenic factors via immunohistochemical evaluation of the maxillary tissues in zoledronic acid osteonecrosis. The retrospective study included a group of 51 patients with various types of cancers, diagnosed with stage 2 or 3 MRONJ at zoledronic acid and treated surgically. Immunohistochemical expressions of αSMA, CD3, CD4, CD8, CD20, CD79α, CD68, CD204, and tryptase were evaluated. Immunohistochemical markers expressions were statistically analyzed according to the duration of the treatment, the trigger factor, the location of the MRONJ, and the healing status. Analysis of the immune response included T lymphocytes, B lymphocytes, plasma cells, macrophages, and mast cells. The duration of treatment significantly influenced the immunohistochemical expression of most markers (p < 0.05). For an increasing trend in treatment duration, a decreasing trend in marker score was observed, suggesting an inverse correlation. The expression of the markers was different depending on the trigger factor, on MRONJ localization (maxilla/mandible), and the healing status, being more intense in patients cured per primam compared to those who had relapses. The patient's immune response was negatively influenced by the duration of the treatment, the trigger factor, the location of the lesion in the mandible, and the recurrence of MRONJ.

Immune Dysfunction in Medication-Related Osteonecrosis of the Jaw

The pathogenesis of medication-related osteonecrosis of the jaw (MRONJ) is multifactorial and there is a substantial consensus on the role of antiresorptive drugs (ARDs), including bisphosphonates (BPs) and denosumab (Dmab), as one of the main determinants. The time exposure, cumulative dose and administration intensity of these drugs are critical parameters to be considered in the treatment of patients, as cancer patients show the highest incidence of MRONJ. BPs and Dmab have distinct mechanisms of action on bone, but they also exert different effects on immune subsets which interact with bone cells, thus contributing to the onset of MRONJ. Here, we summarized the main effects of ARDs on the different immune cell subsets, which consequently affect bone cells, particularly osteoclasts and osteoblasts. Data from animal models and MRONJ patients showed a deep interference of ARDs in modulating immune cells, even though a large part of the literature concerns the effects of BPs and there is a lack of data on Dmab, demonstrating the need to further studies.

Effect of a Three-Day Course of Dexamethasone on Acute Phase Response Following Treatment With Zoledronate: A Randomized Controlled Trial

Zoledronate is a potent intravenous bisphosphonate effective in the management of osteoporosis, Paget's disease and skeletal-related events in malignancy. Its most frequent adverse effect is the acute phase response (APR), an inflammatory reaction characterized by fever, musculoskeletal pain, headache, and nausea. This randomized, placebo-controlled, double-blind study investigated the efficacy of a three-day course of dexamethasone 4 mg daily in reducing incidence of APR. Participants (n = 60) were randomized to receive either 4 mg of oral dexamethasone 1.5 hours before zoledronate and once a day for the following 2 days, or placebo. Oral temperature was measured at baseline and three times a day for the following 3 days, and questionnaires assessing symptoms of the APR were completed at baseline and for 3 days following zoledronate. Use of anti-inflammatory medication in the 3 days following zoledronate was recorded. The primary outcome was the temperature change from baseline. There was a significant difference in the primary outcome between the dexamethasone and placebo groups (p < 0.0001), with a mean decrease in temperature of 0.10°C (95% confidence interval [CI], -0.34 to 0.14) in the dexamethasone group compared with a mean increase in temperature of 0.84°C (95% CI, 0.53-1.16) in the placebo group on the evening following zoledronate. There was also a difference in APR-related symptom score over time between the two groups (p = 0.0005), with a median change in symptom score in the dexamethasone group 1 day after zoledronate of 0 (95% CI, 0-1) compared with 3 (95% CI, 0-5) in the placebo group. An increase in temperature of ≥1°C to a temperature of >37.5°C occurred in two of 30 (6.7%) participants in the dexamethasone group compared with 14 of 30 participants (46.7%) in the placebo group (p = 0.0005). This study demonstrates that a 3-day course of dexamethasone substantially reduces the APR following zoledronate infusion. © 2023 American Society for Bone and Mineral Research (ASBMR).

Effect of oral zoledronate administration on bone turnover in older women

AIM

The aim of this work is to assess the safety and efficacy of two oral zoledronate preparations by determining their effects on bone resorption in healthy postmenopausal women.

METHODS

The preparations studied were zoledronic acid in enteric-coated capsules or a microparticle preparation of zoledronic acid in these capsules. Bone resorption was measured as β-C-telopeptideof type I collagen (CTX) in fasting serum. Separate cohorts, each of five women, were recruited and allocated in sequence to single doses of 20 mg, 40 mg, or 60 mg of oral zoledronate.

RESULTS

Zoledronate 20 mg enteric capsules were well tolerated, reduced serum CTX by a median 51% at 1 week, but by only 17% at 1 month. Doses of 40 or 60 mg of this preparation produced APR and/or gastrointestinal symptoms in more than half of participants. With these doses, median CTX reduction at 1 week was >80%, ~70% at 1 month, but only ~30% at 6 months. Enteric capsules containing microparticles of zoledronate 20 mg reduced CTX by a median 53% at 1 week, with offset over 3 months. Two or three of these capsules dosed weekly reduced CTX by ~50% at 1 month, and by ~30% at 3 and 6 months.

CONCLUSIONS

Oral zoledronate 20 mg circumvents the problem of APR symptoms but, even with multiple doses, the anti-resorptive effect is smaller and less sustained than with intravenous zoledronate. Probably a viable oral regimen of zoledronate dosing at intervals of weeks to months could be developed, but the advantage of infrequent dosing would be lost.

Reduction effect of oral pravastatin on the acute phase response to intravenous zoledronic acid: protocol for a real-world prospective, placebo-controlled trial

INTRODUCTION

Zoledronic acid (ZA) has been used as a first-line treatment in patients with osteoporosis (OP) who receive an annual injection of 5 mg. However, side effects of bone pain and fever, known as the acute phase response (APR), have often been observed after clinical usage. A meta-analysis reported that the incidence of APR was 49.4% among patients with OP who received ZA for the first time and that 30% of patients with these adverse effects refused treatment in the following year. As a clinically used hypolipidaemic drug, statins can inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase to block the pathway upstream of farnesyl pyrophosphate synthase. This process can decrease the accumulation of isopentenyl pyrophosphate to prevent γδT-cell activation and inflammatory factor production, blocking APR occurrence. The aim of this study is to determine the reduction effect of oral pravastatin on APR and investigate the possible mechanisms underlying the effect in vivo.

METHODS AND ANALYSIS

This will be a single-centre, placebo-controlled trial. Female participants will be allocated at a 1:1 ratio to receive either oral pravastatin or a placebo at 1-hour predose and 24 and 48 hours post-administration of ZA. The primary outcome will be the incidence of APR within 72 hours after ZA infusion. The secondary outcomes will include the occurrence time and severity of APR and the frequency and amount of acetaminophen usage within 72 hours after ZA infusion. This study will determine the preventive effect of oral pravastatin on APR in Chinese patients with OP, supporting the clinical application of ZA to alleviate concerns regarding safety and increase patient compliance.

ETHICS AND DISSEMINATION

This study protocol has been registered with ClinicalTrials.gov. This study protocol was reviewed and approved by the Peking University Third Hospital Medical Science Research Ethics Committee. The results will be published in scientific peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04719481.

γδ T Cells in the Tumor Microenvironment-Interactions With Other Immune Cells

A growing number of studies have shown that γδ T cells play a pivotal role in mediating the clearance of tumors and pathogen-infected cells with their potent cytotoxic, cytolytic, and unique immune-modulating functions. Unlike the more abundant αβ T cells, γδ T cells can recognize a broad range of tumors and infected cells without the requirement of antigen presentation via major histocompatibility complex (MHC) molecules. Our group has recently demonstrated parts of the mechanisms of T-cell receptor (TCR)-dependent activation of Vγ9Vδ2+ T cells by tumors following the presentation of phosphoantigens, intermediates of the mevalonate pathway. This process is mediated through the B7 immunoglobulin family-like butyrophilin 2A1 (BTN2A1) and BTN3A1 complexes. Such recognition results in activation, a robust immunosurveillance process, and elicits rapid γδ T-cell immune responses. These include targeted cell killing, and the ability to produce copious quantities of cytokines and chemokines to exert immune-modulating properties and to interact with other immune cells. This immune cell network includes αβ T cells, B cells, dendritic cells, macrophages, monocytes, natural killer cells, and neutrophils, hence heavily influencing the outcome of immune responses. This key role in orchestrating immune cells and their natural tropism for tumor microenvironment makes γδ T cells an attractive target for cancer immunotherapy. Here, we review the current understanding of these important interactions and highlight the implications of the crosstalk between γδ T cells and other immune cells in the context of anti-tumor immunity.

Tolerability of the first infusion of once-yearly zoledronic acid within one to two weeks after hip fracture surgery

OBJECTIVE

Once-yearly infusions of zoledronic acid (ZA) 5 mg may be optimal for secondary fracture prevention after hip fracture (HF), but there are crucial side effects of ZA. This study assessed the tolerability of the first infusion of once-yearly ZA within one to two weeks after HF surgery and to identify risk factors for acute-phase reactions (APRs) and the decrease in serum calcium (Ca) concentration.

METHODS

We analyzed 84 patients (average age: 83 years, 18 men and 66 women) who met the inclusion criteria. The patients underwent the first infusion of ZA one to two weeks after HF surgery and received antipyretic analgesics and active vitamin D analog.

RESULTS

APRs occurred in ten patients (11.9%) and all these patients had pyrexia (>37.5 °C) and/or other symptoms. The asymptomatic hypocalcemia (serum Ca < 8.3 mg/dL) incidence was 6.0% at 7 days after ZA infusion. Compared with female patients without APRs, female patients with APRs had significantly higher levels of serum 25-dihydroxyvitamin D at baseline and serum C-reactive protein on the day ZA was administered (day 0). Multiple linear regression analyses showed that serum level of tartrate-resistant acid phosphatase-5b were significantly associated with an absolute decrease in serum corrected Ca from day 0 to day 7.

CONCLUSIONS

The first infusion of ZA within one to two weeks after HF surgery was well tolerated with the combined use of antipyretic analgesics and active vitamin D analog. Higher inflammatory condition after surgery which is more likely sensitized by ZA administration may increase the risk of APRs, and high bone turnover may increase hypocalcemia risk.

Acute Phase Reactions After Intravenous Infusion of Zoledronic Acid in Japanese Patients with Osteoporosis: Sub-analyses of the Phase III ZONE Study

In a clinical trial involving Japanese patients with osteoporosis, post hoc analyses were performed to evaluate the incidence of acute phase reactions (APRs) after infusion of zoledronic acid (ZOL). The results highlighted differences in baseline factors between patients with vs without APRs. Changes in efficacy indicators such as bone turnover markers (BTMs) also showed significant differences. We, therefore, investigated the factors involved in the development of APRs in Japanese patients treated with a once-yearly intravenous infusion of ZOL 5 mg for 2 years by assessing the relation between APRs and efficacy. APRs reported in patients with primary osteoporosis from the ZONE study were analyzed post hoc. Baseline factors were compared in patients with vs without APRs, and changes in BTMs and bone mineral density (BMD) were also investigated. In the ZOL group, 51.2% (169/330) of patients developed APRs after the first infusion and 12.3% (33/268) after the second infusion. Comparison of baseline factors showed that patients without APRs in the ZOL group had a significantly higher neutrophil/lymphocyte ratio, lower serum levels of procollagen type I N-terminal propeptide, older age, and higher likelihood of prior bisphosphonate use vs patients with APRs. Patients with APRs showed significantly higher increases in total hip BMD at 6 and 12 months and larger reductions in BTMs vs patients without APRs. Patient profiles differed significantly between patients with vs without APRs, with APRs after the first infusion of ZOL being related to increases in total hip BMD and suppression of BTMs.This study is registered with ClinicalTrials.gov (identifier: NCT01522521; January 31, 2012).

Austalide K from the Fungus Penicillium rudallense Prevents LPS-Induced Bone Loss in Mice by Inhibiting Osteoclast Differentiation and Promoting Osteoblast Differentiation

Osteoporosis is a chronic disease that has become a serious public health problem due to the associated reduction in quality of life and its increasing financial burden. It is known that inhibiting osteoclast differentiation and promoting osteoblast formation prevents osteoporosis. As there is no drug with this dual activity without clinical side effects, new alternatives are needed. Here, we demonstrate that austalide K, isolated from the marine fungus Penicillium rudallenes, has dual activities in bone remodeling. Austalide K inhibits the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and improves bone morphogenetic protein (BMP)-2-mediated osteoblast differentiation in vitro without cytotoxicity. The nuclear factor of activated T cells c1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), dendritic cell-specific transmembrane protein (DC-STAMP), and cathepsin K (CTSK) osteoclast-formation-related genes were reduced and alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and osteopontin (OPN) (osteoblast activation-related genes) were simultaneously upregulated by treatment with austalide K. Furthermore, austalide K showed good efficacy in an LPS-induced bone loss in vivo model. Bone volume, trabecular separation, trabecular thickness, and bone mineral density were recovered by austalide K. On the basis of these results, austalide K may lead to new drug treatments for bone diseases such as osteoporosis.

Addition of dexamethasone to manage acute phase responses following initial zoledronic acid infusion

Acute phase response (APR), including myalgia, influenza-like symptoms, headache, arthralgia, and pyrexia, is the most common adverse reaction to initial zoledronic acid infusion. Dexamethasone plus acetaminophen is effective in significantly reducing the incidence and severity of APR.

INTRODUCTION

Acute phase response (APR), including myalgia, influenza-like symptoms, headache, arthralgia, and pyrexia, is due to immunomodulatory actions and is the most common adverse reaction to zoledronic acid (ZOL). The aims of our study were to compare the differences between acetaminophen and dexamethasone plus acetaminophen on the incidence and severity of APRs and to clarify the clinical factors related to APR with initial ZOL infusion.

METHODS

Patients with osteoporosis receiving their first ZOL infusion (N = 96) were assigned into two groups and given either acetaminophen (58 patients, control group) or acetaminophen plus dexamethasone (38 patients, study group). APRs were assessed through telephone interviews 2 weeks later post-infusion. Clinical, demographic, and serologic data were recorded.

RESULTS

There was a significant increase in the incidence and severity of any APR in the control group than the study group (67% vs. 34%, p = 0.003; 0.69 ± 0.50 vs. 0.34 ± 0.48, p = 0.001). Among the APRs, only myalgia incidence and score were significantly higher in the control group than in the study group. Multivariate analysis demonstrated that previous use of osteoporosis medication and participation in the study group was negatively related to the occurrence of any APR or myalgia. Advanced age was shown to significantly increase myalgia. Study group participants had significantly reduced severity of myalgia. The adherence for redosing ZOL was significantly higher in the study group.

CONCLUSION

Dexamethasone plus acetaminophen is effective in significantly reducing the incidence and severity of APR, especially myalgia, and increasing adherence following initial ZOL infusion.

Zoledronate promotes inflammatory cytokine expression in human CD14-positive monocytes among peripheral mononuclear cells in the presence of γδ T cells

Bisphosphonates distributed to bone exert toxic effects specifically towards osteoclasts. On the other hand, intravenous administration of a nitrogen-containing bisphosphonate (N-BP) such as zoledronate induces acute-phase reactions (APRs), including influenza-like fever 1 day later, indicating an interaction with immunocompetent cells circulating blood. Although it has been reported that activation of γδ T cells is pivotal to induce an APR following treatment with zoledronate, downstream events, including the production of inflammatory cytokines after activation of γδ T cells, remain obscure. We investigated the effects of zoledronate on inflammatory cytokine expression in human peripheral blood mononuclear cells (PBMCs) in vitro. While zoledronate induced mRNA expressions of tumour necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and interferon-γ (IFN-γ) in PBMC, depletion of γδ T cells abolished that zoledronate-induced expression of those cytokines, indicating the necessity of γδ T cells for expression induction by zoledronate. However, which types of cells were responsible for the production of those cytokines in blood remained unclear. As it is generally accepted that monocytes and macrophages are primary sources of inflammatory cytokines, CD14⁺ cells from PBMC were exposed to zoledronate in the presence of PBMC, which resulted in induced expression of mRNAs for IL-1β, IL-6 and IFN-γ, but not for TNF-α. These results indicate that CD14⁺ cells are responsible, at least in part, for the production of IL-1β, IL-6 and IFN-γ in blood exposed to zoledronate. This suggests that CD14⁺ cells play an essential role in the occurrence of APRs following N-BP administration.

Benefits of Bisphosphonate Therapy: Beyond the Skeleton

PURPOSE OF REVIEW

Recent evidence from clinical trials and observational studies raises the possibility that bisphosphonate use might confer a lower risk of cardiovascular disease and cancer, resulting in a mortality benefit. This review summarizes clinical and preclinical studies examining the non-skeletal effects of bisphosphonates.

RECENT FINDINGS

Data from clinical trials are conflicting regarding whether or not bisphosphonates have beneficial effects on mortality, cardiovascular events, or cancer incidence. No clinical trials have assessed these outcomes as primary endpoints, and most trials were shorter than 4 years. Observational data suggest that bisphosphonate users may have lower mortality, delayed progression of vascular calcification and atherosclerotic burden, and reduced incidence of breast and colorectal cancer compared to non-users. Preclinical studies confirm that bisphosphonates can be taken up by macrophages and monocytes, and nitrogen-containing bisphosphonates have the ability to disrupt the mevalonate pathway within these cells. In this manner, bisphosphonates exert anti-atherogenic and anti-cancer effects. Bisphosphonates also appear to exert protective effects on vascular smooth muscle cells and endothelial cells and may have direct cytotoxic effects on cancer cells. The balance of evidence does not support bisphosphonate treatment for the primary purpose of improving non-skeletal outcomes, although appropriately designed controlled trials that further explore this possibility are both justified and required. Patients with skeletal indications for bisphosphonate therapy can be reassured that these agents are not associated with increased mortality, cardiovascular disease, or cancer incidence.

Zoledronate decreases CTLA-4 in vivo and in vitro independently of its action on bone resorption

Acute phase response (APR) following intravenous zoledronate (ZOL) administration is related to activation and increased proliferation of γδ T cells, attributed to the molecular mechanism of action of nitrogen-containing bisphosphonates (N-BPs). ZOL, however, has also been reported to inhibit the proliferation of regulatory T cells in vitro and to reduce the expression of Cytotoxic T-Lymphocyte Antigen-4 (CTLA-4), a negative regulator of T cell activation that is increased in patients with autoimmune diseases. There are, however, no data on the relationship between ZOL treatment and soluble(s)CTLA-4 either in vivo in relevant patient populations or in vitro with the use of assays relevant to the mechanism of action of N-BPs. The objectives of the present study were firstly, to characterize the ZOL-induced APR in patients with inflammatory rheumatic diseases (IRDs) and its relationship with changes in circulating sCTLA-4 and secondly, to investigate the effects of ZOL on CTLA-4 production and expression by peripheral blood mononuclear cells (PBMCs). We studied 10 postmenopausal women with IRDs treated with intravenous ZOL 5 mg. Five women experienced APR (APR+) associated with significant decreases in blood lymphocytes and increases in granulocytes and serum CRP. Serum sCTLA-4 values were increased in all patients before ZOL administration and decreased significantly 72 h after the ZOL infusion (from 30.0 ± 2.9 to 6.3 ± 1.8 ng/ml; p < 0.001) with no differences between APR+ and APR- patients. Consistent with the results of the in vivo study, ZOL (1 μM) decreased the production of sCTLA-4 by 87% and 57% after 3 and 5 days in cultures of peripheral blood mononuclear cells (PBMCs) in vitro, respectively, and inhibited the expression of both cytoplasmic and membrane-bound CTLA-4. Our results reveal a novel immunoregulatory action of ZOL that is not related to its action on bone resorption but might be associated with reported clinically significant extraskeletal outcomes of ZOL treatment.

Preventive Role of Vitamin D Supplementation for Acute Phase Reaction after Bisphosphonate Infusion in Paget's Disease

CONTEXT

Intravenous aminobisphosphonates (N-BPs) can induce an acute phase reaction (APR) in up to 40% to 70% of first infusions, causing discomfort and often requiring intervention with analgesics or antipyretics.

OBJECTIVE

Our aim was to explore the risk factors of APR in a large sample of patients with Paget's disease of bone (PDB) and to assess the possible preventive effects of vitamin D administration.

METHODS

An observational analysis was performed in 330 patients with PDB at the time of N-BP infusion. Then, an interventional study was performed in 66 patients with active, untreated PDB to evaluate if vitamin D administration (oral cholecalciferol 50 000 IU/weekly for 8 weeks before infusion) may prevent APR.

RESULTS

In a retrospective study, APR occurred in 47.6% and 18.3% of naive or previously treated patients, respectively. Its prevalence progressively increased in relation to the severity of vitamin D deficiency, reaching 80.0% in patients with 25-hydroxyvitamin D (25OHD) levels below 10 ng/mL (relative risk (RR) = 3.7; 95% confidence interval (CI) 2.8-4.7, P < .0001), even in cases previously treated with N-BPs. Moreover, APR occurred more frequently in patients who experienced a previous APR (RR = 2.8; 95% CI 1.5-5.2; P < .001) or in carriers of SQSTM1 mutation (RR = 2.3; 95% CI 1.3-4.2; P = .005). In the interventional study, vitamin D supplementation prevented APR in most cases, equivalent to a RR of 0.31 (95% CI 0.14-0.67; P < .005) with respect to prevalence rates of the observational cohort. A similar trend was observed concerning the occurrence of hypocalcemia.

CONCLUSIONS

The achievement of adequate 25OHD levels is recommended before N-BP infusion in order to minimize the risk of APR or hypocalcemia in PDB.

Zoledronate rescues immunosuppressed monocytes in sepsis patients

Severe sepsis is often accompanied by a transient immune paralysis, which is associated with enhanced susceptibility to secondary infections and poor clinical outcomes. The functional impairment of antigen‐presenting cells is considered to be a major hallmark of this septic immunosuppression, with reduced HLA‐DR expression on circulating monocytes serving as predictor of mortality. Unconventional lymphocytes like γδ T‐cells have the potential to restore immune defects in a variety of pathologies including cancer, but their use to rescue sepsis‐induced immunosuppression has not been investigated. Our own previous work showed that Vγ9/Vδ2⁺ γδ T‐cells are potent activators of monocytes from healthy volunteers in vitro, and in individuals with osteoporosis after first‐time administration of the anti‐bone resorption drug zoledronate in vivo. We show here that zoledronate readily induces upregulation of HLA‐DR, CD40 and CD64 on monocytes from both healthy controls and sepsis patients, which could be abrogated by neutralising the pro‐inflammatory cytokines interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α in the cultures. In healthy controls, the upregulation of HLA‐DR on monocytes was proportional to the baseline percentage of Vγ9/Vδ2 T‐cells in the peripheral blood mononuclear cell population. Of note, a proportion of sepsis patients studied here did not show a demonstrable response to zoledronate, predominantly patients with microbiologically confirmed bloodstream infections, compared with sepsis patients with more localised infections marked by negative blood cultures. Taken together, our results suggest that zoledronate can, at least in some individuals, rescue immunosuppressed monocytes during acute sepsis and thus may help improve clinical outcomes during severe infection.

γδ cell-based immunotherapy for cancer

Introduction: Cancer immunotherapy relies on the development of an efficient and long-lasting anti-tumor response, generally mediated by cytotoxic T cells. γδ T cells possess distinctive features that justify their use in cancer immunotherapy. Areas covered: Here we will review our current knowledge on the functions of human γδ T cells that may be relevant in tumor immunity and the most recent advances in our understanding of how these functions are regulated in the tumor microenvironment. We will also discuss the major achievements and limitations of γδ T cell-based immunotherapy of cancer. Expert opinion: Several small-scale clinical trials have been conducted in cancer patients using either in vivo activation of γδ T cells or adoptive transfer of ex vivo-expanded γδ T cells. Both strategies are safe and give some clinical benefit to patients, thus providing a proof of principle for their utilization in addition to conventional therapies. However, low objective response rates have been obtained in both settings and therefore larger and well-controlled trials are needed. Discovering the factors which influence the success of γδ T cell-based immunotherapy will lead to a better understanding of their mechanism of action and to harness these cells for effective and durable anti-tumor responses.

Tissue Adaptations of Memory and Tissue-Resident Gamma Delta T Cells

Epithelial and mucosal barriers are critical interfaces physically separating the body from the outside environment and are the tissues most exposed to microorganisms and potential inflammatory agents. The integrity of these tissues requires fine tuning of the local immune system to enable the efficient elimination of invasive pathogens while simultaneously preserving a beneficial relationship with commensal organisms and preventing autoimmunity. Although they only represent a small fraction of circulating and lymphoid T cells, γδ T cells form a substantial population at barrier sites and even outnumber conventional αβ T cells in some tissues. After their egress from the thymus, several γδ T cell subsets naturally establish residency in predetermined mucosal and epithelial locations, as exemplified by the restricted location of murine Vγ5⁺ and Vγ3Vδ1⁺ T cell subsets to the intestinal epithelium and epidermis, respectively. Because of their preferential location in barrier sites, γδ T cells are often directly or indirectly influenced by the microbiota or the pathogens that invade these sites. More recently, a growing body of studies have shown that γδ T cells form long-lived memory populations upon local inflammation or bacterial infection, some of which permanently populate the affected tissues after pathogen clearance or resolution of inflammation. Natural and induced resident γδ T cells have been implicated in many beneficial processes such as tissue homeostasis and pathogen control, but their presence may also exacerbate local inflammation under certain circumstances. Further understanding of the biology and role of these unconventional resident T cells in homeostasis and disease may shed light on potentially novel vaccines and therapies.

CRISPR-mediated TCR replacement generates superior anticancer transgenic T cells

Adoptive transfer of T cells genetically modified to express a cancer-specific T-cell receptor (TCR) has shown significant therapeutic potential for both hematological and solid tumors. However, a major issue of transducing T cells with a transgenic TCR is the preexisting expression of TCRs in the recipient cells. These endogenous TCRs compete with the transgenic TCR for surface expression and allow mixed dimer formation. Mixed dimers, formed by mispairing between the endogenous and transgenic TCRs, may harbor autoreactive specificities. To circumvent these problems, we designed a system where the endogenous TCR-β is knocked out from the recipient cells using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9) technology, simultaneously with transduction with a cancer-reactive receptor of choice. This TCR replacement strategy resulted in markedly increased surface expression of transgenic αβ and γδ TCRs, which in turn translated to a stronger, and more polyfunctional, response of engineered T cells to their target cancer cell lines. Additionally, the TCR-plus-CRISPR-modified T cells were up to a thousandfold more sensitive to antigen than standard TCR-transduced T cells or conventional model proxy systems used for studying TCR activity. Finally, transduction with a pan-cancer-reactive γδ TCR used in conjunction with CRISPR/Cas9 knockout of the endogenous αβ TCR resulted in more efficient redirection of CD4+ and CD8+ T cells against a panel of established blood cancers and primary, patient-derived B-cell acute lymphoblastic leukemia blasts compared with standard TCR transfer. Our results suggest that TCR transfer combined with genome editing could lead to new, improved generations of cancer immunotherapies.

Current Advances in γδ T Cell-Based Tumor Immunotherapy

γδ T cells are a minor population (~5%) of CD3 T cells in the peripheral blood, but abound in other anatomic sites such as the intestine or the skin. There are two major subsets of γδ T cells: those that express Vδ1 gene, paired with different Vγ elements, abound in the intestine and the skin, and recognize the major histocompatibility complex (MHC) class I-related molecules such as MHC class I-related molecule A, MHC class I-related molecule B, and UL16-binding protein expressed on many stressed and tumor cells. Conversely, γδ T cells expressing the Vδ2 gene paired with the Vγ9 chain are the predominant (50-90%) γδ T cell population in the peripheral blood and recognize phosphoantigens (PAgs) derived from the mevalonate pathway of mammalian cells, which is highly active upon infection or tumor transformation. Aminobisphosphonates (n-BPs), which inhibit farnesyl pyrophosphate synthase, a downstream enzyme of the mevalonate pathway, cause accumulation of upstream PAgs and therefore promote γδ T cell activation. γδ T cells have distinctive features that justify their utilization in antitumor immunotherapy: they do not require MHC restriction and are less dependent that αβ T cells on co-stimulatory signals, produce cytokines with known antitumor effects as interferon-γ and tumor necrosis factor-α and display cytotoxic and antitumor activities in vitro and in mouse models in vivo. Thus, there is interest in the potential application of γδ T cells in tumor immunotherapy, and several small-sized clinical trials have been conducted of γδ T cell-based immunotherapy in different types of cancer after the application of PAgs or n-BPs plus interleukin-2 in vivo or after adoptive transfer of ex vivo-expanded γδ T cells, particularly the Vγ9Vδ2 subset. Results from clinical trials testing the efficacy of any of these two strategies have shown that γδ T cell-based therapy is safe, but long-term clinical results to date are inconsistent. In this review, we will discuss the major achievements and pitfalls of the γδ T cell-based immunotherapy of cancer.

Synergistic targeting of breast cancer stem-like cells by human γδ T cells and CD8+ T cells

The inherent resistance of cancer stem cells (CSCs) to existing therapies has largely hampered the development of effective treatments for advanced malignancy. To help develop novel immunotherapy approaches that efficiently target CSCs, an experimental model allowing reliable distinction of CSCs and non-CSCs was set up to study their interaction with non-MHC-restricted γδ T cells and antigen-specific CD8+ T cells. Stable lines with characteristics of breast CSC-like cells were generated from ras-transformed human mammary epithelial (HMLER) cells as confirmed by their CD44hi CD24lo GD2+ phenotype, their mesenchymal morphology in culture and their capacity to form mammospheres under non-adherent conditions, as well as their potent tumorigenicity, self-renewal and differentiation in xenografted mice. The resistance of CSC-like cells to γδ T cells could be overcome by inhibition of farnesyl pyrophosphate synthase (FPPS) through pretreatment with zoledronate or with FPPS-targeting short hairpin RNA. γδ T cells induced upregulation of MHC class I and CD54/ICAM-1 on CSC-like cells and thereby increased the susceptibility to antigen-specific killing by CD8+ T cells. Alternatively, γδ T-cell responses could be specifically directed against CSC-like cells using the humanised anti-GD2 monoclonal antibody hu14.18K322A. Our findings identify a powerful synergism between MHC-restricted and non-MHC-restricted T cells in the eradication of cancer cells including breast CSCs. Our research suggests that novel immunotherapies may benefit from a two-pronged approach combining γδ T-cell and CD8+ T-cell targeting strategies that triggers effective innate-like and tumour-specific adaptive responses.

Effect of single-dose dexamethasone on acute phase response following zoledronic acid: a randomized controlled trial

Zoledronic acid provokes an inflammatory reaction, or acute phase response, in some individuals. We examined whether treatment with dexamethasone could prevent this response. A single dose of dexamethasone 4 mg, given at the time of zoledronic acid infusion, did not influence the incidence or severity of the acute phase response.

INTRODUCTION

The potent bisphosphonate zoledronic acid (ZOL) is used to treat osteoporosis, Paget's disease, and hypercalcemia of malignancy. This medication can provoke an inflammatory reaction, known as the acute phase response (APR). We examined whether glucocorticoid treatment at the time of first exposure to ZOL prevents the development of APR.

METHODS

This double-blind, randomized, controlled trial assessed 40 adults receiving ZOL 5 mg intravenously for the first time. Participants received oral dexamethasone 4 mg (n = 20) or placebo (n = 20) at the time of ZOL infusion. Oral temperature was measured at baseline and three times a day for 3 days following infusion. Symptoms of APR were assessed via questionnaire at baseline then daily for 3 days and again at day 15 post-infusion. Use of rescue medications (paracetamol or ibuprofen) in the 3 days following infusion was evaluated. Primary outcome was between-group difference in temperature change from baseline.

RESULTS

There was no significant difference in temperature change (p = 0.95) or symptom score (p = 0.42) in the 3 days following ZOL between dexamethasone and placebo recipients. Eleven (55%) in the dexamethasone group and 10 (50%) placebo recipients experienced a temperature increase of ≥1 °C (p = 0.99). Seven (35%) in the dexamethasone group and 9 (45%) in the placebo group experienced an increase in symptom score of ≥3 points (p = 0.75). Thirteen (65%) dexamethasone recipients and 12 (60%) in the placebo group required rescue medications (p = 0.99). Dexamethasone was well-tolerated.

CONCLUSIONS

A single dose of dexamethasone 4 mg does not influence the incidence or severity of APR following first exposure to ZOL.

TRIAL REGISTRATION

ACTRN12615000794505.

Immune-mediated syndromes following intravenous bisphosphonate therapy

OBJECTIVES

Intravenous (IV) infusion of aminobisphosphonates (ABP) induces cytokine release by peripheral blood Vγ9δ2 T cells, resulting in an immediate short-term inflammatory response in up to 50% of patients. We evaluated possible long-term pro-inflammatory effects of IV ABP.

METHODS

Retrospective case-series study from one rheumatology specialist's clinic. 2261 electronic charts were reviewed for administration of 'zoledronate' or different brand names of zoledronic acid, and relevant clinical data was retrieved for patients who had received the infusion.

RESULTS

Thirteen patients had recieved zoledronate. In six, new-onset or exacerbation of a previous inflammatory/autoimmune disorder was diagnosed within 3 months following infusion. Of these, one patient developed new-onset rheumatoid arthritis (RA), two polymyalgia rheumatica (PMR), two suffered a flare of Crohn's disease-related and aromatase inhibitor-induced arthralgias, and one patient acquired autoimmune hemophilia. Pre-existing malignancy and immediate inflammatory response following zoledronate were more frequent in patients experiencing new or worsening immunologic manifestations (3/6 vs. 0/7, and 5/6 vs. 2/7, respectively).

CONCLUSIONS

Intravenous ABP may trigger induction of persistent autoimmune syndromes, especially when accompanied by an immediate adverse reaction or pre-existing malignancy.

Immune cell profile of dental pulp tissue treated with zoledronic acid

AIM

To characterize the pulp immune cell profile in the teeth of rats treated with zoledronic acid (ZA).

METHODOLOGY

Male Wistar rats (n = 6 per group) received four intravenous infusions of ZA at doses of 0.04, 0.20 or 1.00 mg kg^-1 ZA or saline (control). On the 70th experimental day, they were euthanized. The first right molar was examined microscopically and submitted to toluidine blue reaction and immunohistochemical for CD68, tumour necrosis Factor (TNF)-α, interleukin (IL)-1β, inducible nitric oxide synthase (iNOS), nuclear factor kappa B (NF-kB) and IL-18 binding protein (IL-18 bp). The presence of ectasic/dilated vessels and inflammatory cells was analysed, and mast cells and mononuclear CD68-positive cells were counted along with the intensity of immunostaining (0-3) for inflammatory markers in odontoblasts and nonodontoblasts pulp cells. The Kruskal-Wallis/Dunn's test (scores or quantitative data) and the chi-squared test (categorical data) were used (GraphPad Prism 5.0, P < 0.05).

RESULTS

There was no differences in the number of animals exhibiting dilated/ectasic blood vessels (P = 0.242) and inflammatory cells (P = 0.489) or in the number of mast cells (P = 1.000). However, there was an increase in mononuclear CD68-positive cells (P = 0.026), immunostaining of TNF-α (P = 0.020), IL-1β (P = 0.027) and iNOS (P = 0.001) in odontoblasts, and IL-1β (P = 0.013) in nonodontoblast pulp cells dose-dependently. NFkB (nucleus and cytoplasm) and IL-18 bp did not differ between groups.

CONCLUSION

ZA modified the immune cell profile in the dental pulp, increasing the number of macrophages and expression of pro-inflammatory markers independent of NFkB.

Prevention of Vγ9Vδ2 T Cell Activation by a Vγ9Vδ2 TCR Nanobody

Vγ9Vδ2 T cell activation plays an important role in antitumor and antimicrobial immune responses. However, there are conditions in which Vγ9Vδ2 T cell activation can be considered inappropriate for the host. Patients treated with aminobisphosphonates for hypercalcemia or metastatic bone disease often present with a debilitating acute phase response as a result of Vγ9Vδ2 T cell activation. To date, no agents are available that can clinically inhibit Vγ9Vδ2 T cell activation. In this study, we describe the identification of a single domain Ab fragment directed to the TCR of Vγ9Vδ2 T cells with neutralizing properties. This variable domain of an H chain-only Ab (VHH or nanobody) significantly inhibited both phosphoantigen-dependent and -independent activation of Vγ9Vδ2 T cells and, importantly, strongly reduced the production of inflammatory cytokines upon stimulation with aminobisphosphonate-treated cells. Additionally, in silico modeling suggests that the neutralizing VHH binds the same residues on the Vγ9Vδ2 TCR as the Vγ9Vδ2 T cell Ag-presenting transmembrane protein butyrophilin 3A1, providing information on critical residues involved in this interaction. The neutralizing Vγ9Vδ2 TCR VHH identified in this study might provide a novel approach to inhibit the unintentional Vγ9Vδ2 T cell activation as a consequence of aminobisphosphonate administration.

Immune cellular profile of bisphosphonate-related osteonecrosis of the jaw

OBJECTIVES

Characterize the cell profile and immunostaining of proinflammatory markers in an experimental model of bisphosphonate-related osteonecrosis of the jaw (BRONJ).

MATERIALS AND METHODS

Male Wistar rats (n = 6-7) were treated chronically with saline solution or zoledronic acid (ZA) at 0.04, 0.20, and 1.00 mg kg(-1) (1.4 × 10(-7) , 6.9 × 10(-6) , and 3.4 × 10(-5)  mol kg(-1) ), and subsequently, the first left inferior molar was extracted. Were performed counting of viable and empty osteocyte lacunae, viable and apoptotic osteoclasts, polymorphonuclear neutrophil, mast cells (toluidine blue), and the positive presence cells for CD68, tumor necrosis factor-alpha (TNF-α), IL (interleukin)-1β, inducible nitric oxide synthase (iNOS), nuclear factor-kappa B (NF-kB) and IL-18 binding protein (IL-18 bp).

RESULTS

BRONJ was showed in ZA treated with 0.20 and 1.00 mg kg(-1) . There is a dose dependent increase in percentage of empty osteocyte lacunae (P < 0.001) and apoptotic osteoclasts (P < 0.001), counting of total osteoclasts (P = 0.003), polymorphonuclear neutrophil cells (P = 0.009), cytoplasmic-positive cells of CD68 (P < 0.001), TNF-α (P = 0.001), IL-1β (P = 0.001), iNOS (P < 0.001), NF-kB (P = 0.006), and nuclear-positive cells of NF-kB (P = 0.011). Consequently, there is no difference in mast cells (P = 0.957), and IL-18 bp immunostaining decreases dose dependently (P = 0.005).

CONCLUSIONS

BRONJ is characterized by increases in immunostaining for proinflammatory markers and NF-kB and inversely associated with cells exhibiting IL-18 bp.

Severe non-infective systemic inflammatory response syndrome, shock, and end-organ dysfunction after zoledronic acid administration in a child

INTRODUCTION

Zoledronic acid is an intravenous bisphosphonate used to increase bone mineral density and reduce the risk of fractures. Its safety profile compares well with pamidronate in pediatric patients. We describe an acute, severe, life-threatening, inflammatory reaction in a child.

METHODS

A 7-year-old boy with complex medical problems and chronic ventilator requirements was admitted to the pediatric intensive care unit (due to ventilator needs) for zoledronic acid infusion and subsequent monitoring. His history was significant for osteoporosis secondary to immobilization with multiple fractures since 2 years of age, hypoxic-ischemic encephalopathy, quadriplegic cerebral palsy, seizure disorder, ventilator dependence, and pulmonary hypertension. He had previously been treated with four cycles of pamidronate without adverse events. He received 0.013 mg/kg of zoledronic acid infused over 30 minutes. Beginning 3 hours after completion of the infusion, he developed progressive tachycardia, fever, hypotension requiring vasopressor infusion, and increasing oxygen requirements. Laboratory studies revealed leukopenia, thrombocytopenia, elevated C-reactive protein, abnormal coagulation profile, metabolic acidosis, and negative cultures. The following day, he developed moderate acute respiratory distress syndrome and pulmonary hemorrhage requiring higher ventilatory settings, and subsequently diarrhea and abdominal distension. Initial clinical resolution was noted from the third day onward, and he was discharged on the sixth day after zoledronate administration.

RESULTS

Our pediatric patient demonstrated an acute, severe, life-threatening reaction to zoledronic acid requiring intensive cardiorespiratory support without an underlying pre-existing inflammatory disorder.

CONCLUSION

Our case highlights the importance of careful monitoring of children following zoledronic acid therapy. We recommend inpatient observation after an initial infusion of zoledronic acid in medically complex children. Children and their parents should be thoroughly counseled on the potential risks of bisphosphonate treatment, which can sometimes be severe and life threatening.

Highly specific and potently activating Vγ9Vδ2-T cell specific nanobodies for diagnostic and therapeutic applications

Vγ9Vδ2-T cells constitute the predominant subset of γδ-T cells in human peripheral blood and have been shown to play an important role in antimicrobial and antitumor immune responses. Several efforts have been initiated to exploit these cells for cancer immunotherapy, e.g. by using phosphoantigens, adoptive cell transfer, and by a bispecific monoclonal antibody based approach. Here, we report the generation of a novel set of Vγ9Vδ2-T cell specific VHH (or nanobody). VHH have several advantages compared to conventional antibodies related to their small size, stability, ease of generating multispecific molecules and low immunogenicity. With high specificity and affinity, the anti-Vγ9Vδ2-T cell receptor VHHs are shown to be useful for FACS, MACS and immunocytochemistry. In addition, some VHH were found to specifically activate Vγ9Vδ2-T cells. Besides being of possible immunotherapeutic value, these single domain antibodies will be of great value in the further study of this important immune effector cell subset.

Do measurements of inflammatory mediators in blood predict recurrence in patients with bisphosphonate-related osteonecrosis of the jaws?

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is well-recognised, difficult to manage, and often recurs. The aim of this study was to examine the value of preoperative measurements of inflammatory mediators in blood in 212 patients with BRONJ who were studied prospectively. Multiple logistic regression analysis was used to assess the importance of the amounts of substances in the blood that are independently associated with the dependent variable "recurrence of BRONJ". The only factor that significantly influenced the development of recurrent BRONJ was reduction in the white cell count (p<0.0001; hazard ratio 5.324; 95% CI 2.373 to 11.945). Neither white cell counts nor C-reactive protein concentrations within or above the reference ranges were significantly associated with recurrent BRONJ. Patients whose white cell counts were lower than the reference range were at increased risk of recurrent BRONJ. This may be a marker of reduced immunocompetence, and additional prophylactic measures or treatment should be considered for these patients.

The best of both worlds - managing the cancer, saving the bone

In the context of breast cancer, the importance of the skeleton in the regulation of primary tumour development and as a site for subsequent metastasis is well characterized. Our understanding of the contributions made by the host bone and bone marrow cells increasingly demonstrates the extent of the interaction between tumour cells and normal host cells. As a result, the need to develop and utilize therapies that can impede the growth and/or function of tumour cells while sparing normal host bone and bone marrow cells is immense and expanding. The need for these new treatments is, however, superimposed on the orthopaedic management of patients' quality of life, where pain control and continued locomotion are paramount. Indeed, the majority of the anticancer therapies used to date often result in direct or indirect damage to bone. Thus, although the bone microenvironment regulates tumour cell growth in bone, cells within the bone marrow niche also mediate many of the orthopaedic consequences of tumour progression as well as resistance to the antitumour effects of existing therapies. In this Review, we highlight the effects of existing cancer treatments on bone and the bone marrow microenvironment as well as the mechanisms mediating these effects and the current utility of modern orthopaedic interventions.

The promise of γδ T cells and the γδ T cell receptor for cancer immunotherapy

γδ T cells form an important part of adaptive immune responses against infections and malignant transformation. The molecular targets of human γδ T cell receptors (TCRs) remain largely unknown, but recent studies have confirmed the recognition of phosphorylated prenyl metabolites, lipids in complex with CD1 molecules and markers of cellular stress. All of these molecules are upregulated on various cancer types, highlighting the potential importance of the γδ T cell compartment in cancer immunosurveillance and paving the way for the use of γδ TCRs in cancer therapy. Ligand recognition by the γδ TCR often requires accessory/co-stimulatory stress molecules on both T cells and target cells; this cellular stress context therefore provides a failsafe against harmful self-reactivity. Unlike αβ T cells, γδ T cells recognise their targets irrespective of HLA haplotype and therefore offer exciting possibilities for off-the-shelf, pan-population cancer immunotherapies. Here, we present a review of known ligands of human γδ T cells and discuss the promise of harnessing these cells for cancer treatment.

The safety and tolerability profile of therapies for the prevention and treatment of osteoporosis in postmenopausal women

At a time when the prevalence of osteoporosis and related fractures is increasing, initiation and continuation of pharmacologic therapies for prevention and treatment of postmenopausal osteoporosis have declined. This decline has been at least in part attributable to concerns about safety of these agents, such as atypical fractures with bisphosphonates and breast cancer with estrogen/progestin therapy, particularly when they are used long term by older women. However, in many cases, absolute risk of serious adverse effects is small and should be balanced against the larger potential for fracture reduction. Here, we review the safety and tolerability of available therapies for postmenopausal osteoporosis. Taking into consideration their relative efficacy, we also provide strategies for optimization of the risk:benefit ratio.

Effect of different doses of zoledronic acid in establishing of bisphosphonate-related osteonecrosis

OBJECTIVES

To establish osteonecrosis of the jaws in rats treated with different doses of zoledronic acid (ZA).

METHODS

Male Wistar rats (n=6-7) received three consecutive weekly intravenous ZA infusions at doses of 0.04, 0.20 or 1.00mg/kg ZA or saline (control). Four weeks after the last administration, the animals were submitted to simple extraction of the lower left first molar. An additional dose of ZA was administered seven days later, and the animals were sacrificed 28 days after exodontia. Weight was measured and blood was collected weekly for analysis. The jaw was radiographically and microscopically examined along with the liver, spleen, kidney and stomach.

RESULTS

All ZA doses showed a higher radiolucent area than the control (p<0.0001), but the dose of 0.04mg/kg did not show BRONJ. Doses of 0.20 and 1.00mg/kg ZA showed histological evidence of bone necrosis (p=0.0004). Anaemia (p<0.0001, r(2)=0.8073) and leucocytosis (p<0.0001, r(2)=0.9699) are seen with an increase of lymphocytes (p<0.0001, r(2)=0.6431) and neutrophils and monocytes (p=0.0218, r(2)=0.8724) in all the animals treated with an increasing dose of ZA. Haemorrhage and ectasia were observed in the spleen (p=0.0004) and stomach (p=0.0168) in a dose-dependent manner, and the animals treated with ZA showed a lower rate of weight gain (p<0.0001).

CONCLUSIONS

We designed a bisphosphonate-related osteonecrosis of the jaw model that reproduces radiographic and histological parameters and mimics clinical alterations such as leucocytosis, anaemia and idiosyncratic inflammatory post infusion reactions.

Gamma-delta T lymphocytes and 25-hydroxy vitamin D levels as key factors in autoimmunity and inflammation: the case of zoledronic acid-induced acute phase reaction

Zoledronic acid (ZA) infusion for osteoporosis is frequently associated with the onset of an acute phase reaction (APR) secondary to the activation of γδ T cell receptor (TCR) lymphocytes (γδ T cells) and to low vitamin D levels, similar to what is observed in chronic inflammation and autoimmunity. In this study we investigated whether the phenotype of γδ T cells is associated with APR and 25-OH vitamin D (25-OHvD) levels. For flow-cytometry analysis, peripheral blood samples were obtained from 52 osteoporotic women prior to 5 mg ZA intravenous infusion and from nine women (five with APR) one week later. Twenty-six/52 (50%) patients reported APR and APR+ cases had a higher percentage of central memory Th1-like γδ T cells. One week after ZA infusion, APR was associated with a decreased percentage of central memory Th1-like γδ T cells, an increase in the percentage and activation of effector memory Th1-like γδ T cells, and an increase in Th17-like γδ T cells. Lower 25-OHvD levels were significantly associated with APR, but no correlation was found between 25-OHvD level and γδ T cell percentage or subsets. In conclusion, patients experiencing APR related to ZA infusion have lower 25-OHvD levels and we suggest that the higher percentage of central memory Th1-like γδ T cells and the expansion of effector memory Th1-like and Th17-like γδ T cells are associated with the occurrence of APR.

Human Vγ9/Vδ2 T cells: Innate adaptors of the immune system

Unconventional T cells are gaining center stage as important effector and regulatory cells that orchestrate innate and adaptive immune responses. Human Vγ9/Vδ2 T cells are amongst the best understood unconventional T cells, as they are easily accessible in peripheral blood, can readily be expanded and manipulated in vitro, respond to microbial infections in vivo and can be exploited for novel tumor immunotherapies. We here review findings that suggest that Vγ9/Vδ2 T cells, and possibly other unconventional human T cells, play an important role in bridging innate and adaptive immunity by promoting the activation and differentiation of various types of antigen-presenting cells (APCs) and even turning into APCs themselves, and thereby pave the way for antigen-specific effector responses and long-term immunological memory. Although the direct physiological relevance for most of these mechanisms still needs to be demonstrated in vivo, these findings may have implications for novel therapies, diagnostic tests and vaccines.

Zoledronic acid causes γδ T cells to target monocytes and down-modulate inflammatory homing

Zoledronic acid (ZA) is a potential immunotherapy for cancer because it can induce potent γδ T-cell-mediated anti-tumour responses. Clinical trials are testing the efficacy of intravenous ZA in cancer patients; however, the effects of systemic ZA on the activation and migration of peripheral γδ T cells remain poorly understood. We found that γδ T cells within ZA-treated peripheral blood mononuclear cells were degranulating, as shown by up-regulated expression of CD107a/b. Degranulation was monocyte dependent because CD107a/b expression was markedly reduced in the absence of CD14(+) cells. Consistent with monocyte-induced degranulation, we observed γδ T-cell-dependent induction of monocyte apoptosis, as shown by phosphatidylserine expression on monocytes and decreased percentages of monocytes in culture. Despite the prevailing paradigm that ZA promotes tumour homing in γδ T cells, we observed down-modulation of their tumour homing capacity, as shown by decreased expression of the inflammatory chemokine receptors CCR5 and CXCR3, and reduced migration towards the inflammatory chemokine CCL5. Taken together our data suggest that ZA causes γδ T cells to target monocytes and down-modulate the migratory programme required for inflammatory homing. This study provides novel insight into how γδ T cells interact with monocytes and the possible implications of systemic use of ZA in cancer.

Crosstalk between bone niche and immune system: osteoimmunology signaling as a potential target for cancer treatment

There is a well recognized link between the bone and the immune system and in recent years there has been a major effort to elucidate the multiple functions of the molecules expressed in both bone and immune cells. Several molecules that were initially identified and studied in the immune system have been shown to have essential functions also in the bone. An interdisciplinary field embracing immune and bone biology has been brought together and called "osteoimmunology". The co-regulation of the skeletal and immune systems strikingly exemplifies the extreme complexity of such an interaction. Their interdependency must be considered in designing therapeutic approaches for either of the two systems. In other words, it is necessary to think of the osteoimmune system as a complex physiological unit. Denosumab was originally introduced to specifically target bone resorption, but it is now under evaluation for its effect on the long term immune response. Similarly, our current and still growing knowledge of the intimate link between the immune system and bone will be beneficial for the safety of drugs targeting either of these integrated systems. Given the large number of molecules exerting functions on both the skeletal and immune systems, osteoimmunological understanding is becoming increasingly important. Both bone and immune systems are frequently disrupted in cancer; and they may be crucial in regulating tumor growth and progression. Some therapies - such as bisphosphonates and receptor activator of NF-κB ligand (RANKL) targeted drugs - that aim at reducing pathologic osteolysis in cancer may interact with the immune system, thus providing potential favorable effects on survival.

A Novel Prothrombotic Pathway in Systemic Sclerosis Patients: Possible Role of Bisphosphonate-Activated γδ T Cells

Objectives: Infusions of aminobisphonates (ABP) activate Vγ9δ2T cells in vivo and induce an acute inflammatory response in 30% of patients treated for osteoporosis. Following the observation of digital thrombosis in a systemic sclerosis (SSc) patient after treatment with an intravenous ABP, zoledronate (Zol), we evaluated whether patient and control peripheral blood (PB) mononuclear cell (MC, PBMC) acquire a prothrombotic phenotype in response to Zol.

Results: Vγ9δ2T cells of both patients and healthy donors (HD) upregulated the CD69 activation antigen and secreted tumor necrosis factor (TNF)α in response to Zol in vitro. In addition, exposure to either Zol or lipopolysaccharide (LPS), or to both additively, induced expression of the highly procoagulant, tissue factor (TF)-1 on CD14+ monocytes. Importantly, only Zol-induced TF-1 was blocked by a monoclonal antibody to TNFα. Interestingly, we found that SSc, but not HD, Vδ1+ T cells were concurrently activated by Zol to produce interleukin (IL)-4. Addition of plasma from the blood of the SSc patient who developed critical digital ischemia after infusion of Zol, but neither plasma from a second patient with no adverse clinical response to Zol infusion nor of a HD, strongly enhanced Zol-induced monocyte TF-1, which could still be blocked by anti-TNFα.

Conclusion: Aminobisphonates induced secretion of TNFα by Vγ9δ2+ T cells may lead to TNFα-dependent induction of procoagulant TF-1 induction on monocytes. In certain clinical settings, e.g., SSc, TF-1+ monocytes could play a role in triggering clinically relevant thrombosis.

Microbe-specific unconventional T cells induce human neutrophil differentiation into antigen cross-presenting cells

The early immune response to microbes is dominated by the recruitment of neutrophils whose primary function is to clear invading pathogens. However, there is emerging evidence that neutrophils play additional effector and regulatory roles. The present study demonstrates that human neutrophils assume Ag cross-presenting functions and suggests a plausible scenario for the local generation of APC-like neutrophils through the mobilization of unconventional T cells in response to microbial metabolites. Vγ9/Vδ2 T cells and mucosal-associated invariant T cells are abundant in blood, inflamed tissues, and mucosal barriers. In this study, both human cell types responded rapidly to neutrophils after phagocytosis of Gram-positive and Gram-negative bacteria producing the corresponding ligands, and in turn mediated the differentiation of neutrophils into APCs for both CD4(+) and CD8(+) T cells through secretion of GM-CSF, IFN-γ, and TNF-α. In patients with acute sepsis, circulating neutrophils displayed a similar APC-like phenotype and readily processed soluble proteins for cross-presentation of antigenic peptides to CD8(+) T cells, at a time when peripheral Vγ9/Vδ2 T cells were highly activated. Our findings indicate that unconventional T cells represent key controllers of neutrophil-driven innate and adaptive responses to a broad range of pathogens.

Neutrophil uptake of nitrogen-bisphosphonates leads to the suppression of human peripheral blood γδ T cells

Nitrogen-bisphosphonates (n-BP), such as zoledronate, are the main class of drugs used for the prevention of osteoporotic fractures and the management of cancer-associated bone disease. However, long-term or high-dose use has been associated with certain adverse drug effects, such as osteonecrosis of the jaw and the loss of peripheral of blood Vγ9Vδ2 T cells, which appear to be linked to drug-induced immune dysfunction. In this report we show that neutrophils present in human peripheral blood readily take up zoledronate, and this phenomenon is associated with the potent immune suppression of human peripheral blood Vγ9Vδ2 T cells. Furthermore, we found this zoledronate-mediated inhibition by neutrophils could be overcome to fully reconstitute Vγ9Vδ2 T cell proliferation by concomitantly targeting neutrophil-derived hydrogen peroxide, serine proteases, and arginase I activity. These findings will enable the development of targeted strategies to mitigate some of the adverse effects of n-BP treatment on immune homeostasis and to improve the success of immunotherapy trials based on harnessing the anticancer potential of peripheral blood γδ T cells in the context of n-BP treatment.

Gamma delta T cells in non-immune patients during primary schistosomal infection

The mevalonate pathway is critical for the survival of Schistosoma. γδ T cells, a small subset of peripheral blood (PB) T cells, recognize low molecular weight phosphorylated antigens in the mevalonate pathway, which drive their expansion to exert protective and immunoregulatory effects. To evaluate their role in schistosomiasis, we measured γδ T cells in the PB of non-immune travelers who contracted Schistosoma hematobium or Schistosoma mansoni in Africa. The maximal level of γδ T-cells following infection was 5.78 ± 2.19% of the total T cells, versus 3.72 ± 3.15% in 16 healthy controls [P = 0.09] with no difference between S. hematobium and S. mansoni in this regard. However, among the nine patients in the cohort who presented with acute schistosomiasis syndrome (AS), the level (3.5 ± 1.9%) was significantly lower than in those who did not (8.6 ± 6.4%, P < 0.05), both before and after therapy. Furthermore, γδ T cells increased significantly in response to praziquantel therapy. In a patient with marked expansion of γδ T cells, most expressed the Vδ2 gene segment, a hallmark of cells responding to cognate antigens in the mevalonate pathways of the parasite or the human host. These results suggest an immunoregulatory role of antigen responsive γδ T cells in the clinical manifestations of early schistosomal infection.

Activated γδ T cells inhibit osteoclast differentiation and resorptive activity in vitro

Extensive evidence suggests that the immune system exerts powerful effects on bone cells, particularly in chronic disease pathologies such as rheumatoid arthritis (RA). The chronic inflammatory state in RA, particularly the excessive production of T cell-derived proinflammatory cytokines such as tumour necrosis factor (TNF)-α and interleukin (IL)-17, triggers bone erosions through the increased stimulation of osteoclast formation and activity. While evidence supports a role for IL-17 and TNF-α secreted by conventional CD4⁺ T cells in RA, recent evidence in animal models of RA have implicated γδ T cells as a major producer of pathogenic IL-17. However, the capacity of γδ T cells to influence osteoclast formation and activity in humans has not yet been investigated widely. To address this issue we investigated the effects of γδ T cells on osteoclast differentiation and resorptive activity. We have demonstrated that anti-CD3/CD28-stimulated γδ T cells or CD4⁺ T cells inhibit human osteoclast formation and resorptive activity in vitro. Furthermore, we assessed cytokine production by CD3/CD28-stimulated γδ T cells and observed a lack of IL-17 production, with activated γδ T cells producing abundant interferon (IFN)-γ. The neutralization of IFN-γ markedly restored the formation of osteoclasts from precursor cells and the resorptive activity of mature osteoclasts, suggesting that IFN-γ is the major factor responsible for the inhibitory role of activated γδ T cells on osteoclastogenesis and resorptive activity of mature osteoclasts. Our work therefore provides new insights on the interactions between γδ T cells and osteoclasts in humans.

Zoledronic acid to prevent and treat cancer metastasis: new prospects for an old drug

Zoledronic acid (zoledronate, Zometa™; Novartis Pharmaceuticals, Basel, Switzerland) is a nitrogen-containing bisphosphonate. Zoledronate rapidly binds to bone mineral where it is then ingested by osteoclasts. Once internalized, zoledronate inhibits the mevalonate pathway, which stops osteoclast function, and thus slows bone resorption. Zoledronate is approved for the prevention of skeletal morbidity in metastatic bone disease from solid tumors and multiple myeloma. Zoledronate is also recommended as an option for the treatment of cancer therapy-induced bone loss. In recent large Phase III studies in early breast cancer, zoledronate reduced both local and distant recurrences in women with induced or established natural menopause. Postulated mechanisms underlying the anticancer properties of zoledronate include antiangiogenic and immunomodulatory effects. A clearer understanding of these mechanisms will enable the full potential of zoledronate to be realized.

Acute phase response after zoledronic acid is associated with long-term effects on white blood cells

We have recently reported a long-lasting decrease in circulating γδ T cells in osteoporotic patients on oral amino-bisphosphonates (N-BPs). Here we verify whether these changes are associated with the occurrence of acute phase response (APR) to intravenous (IV) zoledronic acid (ZOL) or changes of other circulating white blood cells (WBC). WBC count was obtained before and 1 year after a single IV administration of 5 mg ZOL in 36 osteoporotic patients (mean age 72 ± 9, range 45-86 years) without other relevant diseases; 12 of 36 patients developed the classical APR. After 1 year in the patients who experienced an APR, but not in the others, a significant decrease not only of γδ T cells (-30 %), but also of total lymphocytes (-11 %) and eosinophils (-27 %), was observed. The mechanism leading to the observed decrease of circulating lymphocytes and eosinophils remains unclear, but our observation opens a new frontier for the understanding of the immunoeffects of N-BPs.

Osteoporosis - a current view of pharmacological prevention and treatment

Postmenopausal osteoporosis is the most common bone disease, associated with low bone mineral density (BMD) and pathological fractures which lead to significant morbidity. It is defined clinically by a BMD of 2.5 standard deviations or more below the young female adult mean (T-score =−2.5). Osteoporosis was a huge global problem both socially and economically – in the UK alone, in 2011 £6 million per day was spent on treatment and social care of the 230,000 osteoporotic fracture patients – and therefore viable preventative and therapeutic approaches are key to managing this problem within the aging population of today. One of the main issues surrounding the potential of osteoporosis management is diagnosing patients at risk before they develop a fracture. We discuss the current and future possibilities for identifying susceptible patients, from fracture risk assessment to shape modeling and in relation to the high heritability of osteoporosis now that a plethora of genes have been associated with low BMD and osteoporotic fracture. This review highlights the current therapeutics in clinical use (including bisphosphonates, anti-RANKL [receptor activator of NF-κB ligand], intermittent low dose parathyroid hormone, and strontium ranelate) and some of those in development (anti-sclerostin antibodies and cathepsin K inhibitors). By highlighting the intimate relationship between the activities of bone forming (osteoblasts) and bone-resorbing (osteoclasts) cells, we include an overview and comparison of the molecular mechanisms exploited in each therapy.