Extracellular heat shock protein 70 levels in tumour-bearing dogs and cats treated with radiation therapy and hyperthermia

Hyperthermia is a form of a cancer treatment which is frequently applied in combination with radiotherapy (RT) to improve therapy responses and radiosensitivity. The mode of action of hyperthermia is multifactorial; the one hand by altering the amount of the blood circulation in the treated tissue, on the other hand by modulating molecular pathways involved in cell survival processes and immunogenic interactions. One of the most dominant proteins induced by hyperthermia is the major stress-inducible heat shock protein 70 (Hsp70). Hsp70 can be found in the blood either as a free-protein (free HSP70) derived from necrotic cells, or lipid-bound (liposomal Hsp70) when it is actively released in extracellular vesicles (EVs) by living cells. The aim of the study was to evaluate the levels of free and liposomal Hsp70 before and after treatment with RT alone or hyperthermia combined with radiotherapy (HTRT) in dogs and cats to evaluate therapy responses. Peripheral blood was collected from feline and canine patients before and at 2, 4, 6 and 24 h after treatment with RT or HTRT. Hsp70 enzyme-linked immunosorbent assays (ELISAs) were performed to determine the free and liposomal Hsp70 concentrations in the serum. The levels were analysed after the first fraction of radiation to study immediate effects and after all applied fractions to study cumulative effects. The levels of free and liposomal Hsp70 levels in the circulation were not affected by the first singular treatment and cumulative effects of RT in cats however, after finalizing all treatment cycles with HTRT free and liposomal Hsp70 levels significantly increased. In dogs, HTRT, but not treatment with RT alone, significantly affected liposomal Hsp70 levels during the first fraction. Free Hsp70 levels were significantly increased after RT, but not HTRT, during the first fraction in dogs. In dogs, on the other hand, RT alone resulted in a significant increase in liposomal Hsp70, but HTRT did not significantly affect the liposomal Hsp70 when cumulative effects were analysed. Free Hsp70 was significantly induced in dogs after both, RT and HTRT when cumulative effects were analysed. RT and HTRT treatments differentially affect the levels of free and liposomal Hsp70 in dogs and cats. Both forms of Hsp70 could potentially be further investigated as potential liquid biopsy markers to study responses to RT and HTRT treatment in companion animals.

Intercomparison of dose enhancement ratio and secondary electron spectra for gold nanoparticles irradiated by X-rays calculated using multiple Monte Carlo simulation codes

PURPOSE

Targeted radiation therapy has seen an increased interest in the past decade. In vitro and in vivo experiments showed enhanced radiation doses due to gold nanoparticles (GNPs) to tumors in mice and demonstrated a high potential for clinical application. However, finding a functionalized molecular formulation for actively targeting GNPs in tumor cells is challenging. Furthermore, the enhanced energy deposition by secondary electrons around GNPs, particularly by short-ranged Auger electrons is difficult to measure. Computational models, such as Monte Carlo (MC) radiation transport codes, have been used to estimate the physical quantities and effects of GNPs. However, as these codes differ from one to another, the reliability of physical and dosimetric quantities needs to be established at cellular and molecular levels, so that the subsequent biological effects can be assessed quantitatively.

METHODS

In this work, irradiation of single GNPs of 50 nm and 100 nm diameter by X-ray spectra generated by 50 and 100 peak kilovoltages was simulated for a defined geometry setup, by applying multiple MC codes in the EURADOS framework.

RESULTS

The mean dose enhancement ratio of the first 10 nm-thick water shell around a 100 nm GNP ranges from 400 for 100 kVp X-rays to 600 for 50 kVp X-rays with large uncertainty factors up to 2.3.

CONCLUSIONS

It is concluded that the absolute dose enhancement effects have large uncertainties and need an inter-code intercomparison for a high quality assurance; relative properties may be a better measure until more experimental data is available to constrain the models.

P11.42 Magnetic targeting of the granzyme B functionalized nanoparticles for therapy of glioblastoma

BACKGROUND

Magnetic drug targeting by employing external magnetic fields represents a promising approach for treatment of glioblastoma. To increase the anti-tumor therapeutic effect magnetic nanocarriers could be functionalized with tumor-targeting bioligands such as granzyme B (GrB). The serine protease GrB that is produced as an effector molecule by activated NK and T cells can induce specific tumor cell apoptosis.

MATERIAL AND METHODS

The targeting potential of the dextran-coated superparamagnetic iron oxide nanoparticles conjugated with GrB (GrB-SPIONs) was assessed in glioblastoma cells (U87, C6, GL261) by flow cytometry, confocal and electron microscopies. Magnetic field strength (320 mT) in the models of U87 glioblastoma in NMRI nu/nu mice and C6 glioma in Wistar rats was achieved by employing NdFeB cylindrical ferromagnet. The irradiation of the implanted tumors was performed using the CT-image guided Small Animal Radiation Research Platform (SARRP). Accumulation of the nanoparticles was assessed in paraffine-embedded specimens employing Prussian blues staining. Sections were additionally analyzed by IHC for apoptosis (caspase 3).

RESULTS

Synthesized GrB-SPIONs incorporated into the cytoplasm of tumor cells via the endolysosomal pathway and induced apoptosis in a dose-dependent manner. Intravenous injection of GrB-SPIONs resulted in the glioma-specific retention of the nanoparticles as was shown by high-field (11 T) magnetic resonance imaging and biodistribution studies (NLR-M2 measurements). Magnetic targeting of the nanoparticles in vivo drastically enhanced the accumulation of nanoparticles to the location of the magnet. Thus the local retention of nanoparticles was 12.3-fold higher as compared to application of GrB-SPIONs without external magnetic field. The presence of granzyme B on SPIONs has been shown to promote tumor cells death (IHC staining for caspase 3) and significantly increased overall survival. A combination of nanoparticle treatment with a single radiation dose (10 Gy) significantly prolonged the survival of rats as compared to animals treated only with magnetic targeting of GrB-SPIONs or radiotherapy alone (P<0.001).

CONCLUSION

Single-agent therapy with GrB-SPIONs demonstrated an impressive increase in overall survival of tumor-bearing animals. Combinatorial regimen employing magnetic targeting and stereotactic radiotherapy further enhanced the therapeutic potential of magnetic conjugates.

Zero-valent Fe confined mesoporous silica nanocarriers (Fe(0) @ MCM-41) for targeting experimental orthotopic glioma in rats

Mesoporous silica nanoparticles (MSNs) impregnated with zero-valent Fe (Fe(0) @ MCM-41) represent an attractive nanocarrier system for drug delivery into tumor cells. The major goal of this work was to assess whether MSNs can penetrate the blood-brain barrier in a glioblastoma rat model. Synthesized MSNs nanomaterials were characterized by energy dispersive X-ray spectroscopy, measurements of X-ray diffraction, scanning electron microscopy and Mössbauer spectroscopy. For the detection of the MSNs by MR and for biodistribution studies MSNs were labeled with zero-valent Fe. Subsequent magnetometry and nonlinear-longitudinal-response-M2 (NLR-M2) measurements confirmed the MR negative contrast enhancement properties of the nanoparticles. After incubation of different tumor (C6 glioma, U87 glioma, K562 erythroleukemia, HeLa cervix carcinoma) and normal cells such as fibroblasts and peripheral blood mononuclear cells (PBMCs) MSNs rapidly get internalized into the cytosol. Intracellular residing MSNs result in an enhanced cytotoxicity as Fe(0) @ MCM-41 promote the reactive oxygen species production. MRI and histological studies indicated an accumulation of intravenously injected Fe(0) @ MCM-41 MSNs in orthotopic C6 glioma model. Biodistribution studies with measurements of second harmonic of magnetization demonstrated an increased and dose-dependent retention of MSNs in tumor tissues. Taken together, this study demonstrates that MSNs can enter the blood-brain barrier and accumulate in tumorous tissues.

Sub-micrometer 20MeV protons or 45MeV lithium spot irradiation enhances yields of dicentric chromosomes due to clustering of DNA double-strand breaks

In conventional experiments on biological effects of radiation types of diverse quality, micrometer-scale double-strand break (DSB) clustering is inherently interlinked with clustering of energy deposition events on nanometer scale relevant for DSB induction. Due to this limitation, the role of the micrometer and nanometer scales in diverse biological endpoints cannot be fully separated. To address this issue, hybrid human-hamster AL cells have been irradiated with 45MeV (60keV/μm) lithium ions or 20MeV (2.6keV/μm) protons quasi-homogeneously distributed or focused to 0.5×1μm(2) spots on regular matrix patterns (point distances up to 10.6×10.6μm), with pre-defined particle numbers per spot to provide the same mean dose of 1.7Gy. The yields of dicentrics and their distribution among cells have been scored. In parallel, track-structure based simulations of DSB induction and chromosome aberration formation with PARTRAC have been performed. The results show that the sub-micrometer beam focusing does not enhance DSB yields, but significantly affects the DSB distribution within the nucleus and increases the chance to form DSB pairs in close proximity, which may lead to increased yields of chromosome aberrations. Indeed, the experiments show that focusing 20 lithium ions or 451 protons per spot on a 10.6μm grid induces two or three times more dicentrics, respectively, than a quasi-homogenous irradiation. The simulations reproduce the data in part, but in part suggest more complex behavior such as saturation or overkill not seen in the experiments. The direct experimental demonstration that sub-micrometer clustering of DSB plays a critical role in the induction of dicentrics improves the knowledge on the mechanisms by which these lethal lesions arise, and indicates how the assumptions of the biophysical model could be improved. It also provides a better understanding of the increased biological effectiveness of high-LET radiation.

Improved normal tissue protection by proton and X-ray microchannels compared to homogeneous field irradiation

The risk of developing normal tissue injuries often limits the radiation dose that can be applied to the tumour in radiation therapy. Microbeam Radiation Therapy (MRT), a spatially fractionated photon radiotherapy is currently tested at the European Synchrotron Radiation Facility (ESRF) to improve normal tissue protection. MRT utilizes an array of microscopically thin and nearly parallel X-ray beams that are generated by a synchrotron. At the ion microprobe SNAKE in Munich focused proton microbeams ("proton microchannels") are studied to improve normal tissue protection. Here, we comparatively investigate microbeam/microchannel irradiations with sub-millimetre X-ray versus proton beams to minimize the risk of normal tissue damage in a human skin model, in vitro. Skin tissues were irradiated with a mean dose of 2 Gy over the irradiated area either with parallel synchrotron-generated X-ray beams at the ESRF or with 20 MeV protons at SNAKE using four different irradiation modes: homogeneous field, parallel lines and microchannel applications using two different channel sizes. Normal tissue viability as determined in an MTT test was significantly higher after proton or X-ray microchannel irradiation compared to a homogeneous field irradiation. In line with these findings genetic damage, as determined by the measurement of micronuclei in keratinocytes, was significantly reduced after proton or X-ray microchannel compared to a homogeneous field irradiation. Our data show that skin irradiation using either X-ray or proton microchannels maintain a higher cell viability and DNA integrity compared to a homogeneous irradiation, and thus might improve normal tissue protection after radiation therapy.

Magnetic heating properties and neutron activation of tungsten-oxide coated biocompatible FePt core-shell nanoparticles

Magnetic nanoparticles are highly desirable for biomedical research and treatment of cancer especially when combined with hyperthermia. The efficacy of nanoparticle-based therapies could be improved by generating radioactive nanoparticles with a convenient decay time and which simultaneously have the capability to be used for locally confined heating. The core-shell morphology of such novel nanoparticles presented in this work involves a polysilico-tungstate molecule of the polyoxometalate family as a precursor coating material, which transforms into an amorphous tungsten oxide coating upon annealing of the FePt core-shell nanoparticles. The content of tungsten atoms in the nanoparticle shell is neutron activated using cold neutrons at the Heinz Maier-Leibnitz (FRMII) neutron facility and thereby transformed into the radioisotope W-187. The sizeable natural abundance of 28% for the W-186 precursor isotope, a radiopharmaceutically advantageous gamma-beta ratio of γβ≈30% and a range of approximately 1mm in biological tissue for the 1.3MeV β-radiation are promising features of the nanoparticles' potential for cancer therapy. Moreover, a high temperature annealing treatment enhances the magnetic moment of nanoparticles in such a way that a magnetic heating effect of several degrees Celsius in liquid suspension - a prerequisite for hyperthermia treatment of cancer - was observed. A rise in temperature of approximately 3°C in aqueous suspension is shown for a moderate nanoparticle concentration of 0.5mg/ml after 15min in an 831kHz high-frequency alternating magnetic field of 250Gauss field strength (25mT). The biocompatibility based on a low cytotoxicity in the non-neutron-activated state in combination with the hydrophilic nature of the tungsten oxide shell makes the coated magnetic FePt nanoparticles ideal candidates for advanced radiopharmaceutical applications.

Dual role of heat shock proteins (HSPs) in anti-tumor immunity

Although surgery and radiotherapy are highly efficient in local tumor control, distal metastases and tumor recurrence often limit therapeutic outcome. It is becoming progressively more evident that curative tumor therapy depends on the presence and maintenance of an intact immune system which has the capacity to elicit cytotoxic effector functions against circulating tumor cells and distant metastases. Heat shock proteins (HSPs, also termed stress proteins) are involved in antigen processing and presentation and can act as "danger signals" for the adaptive and innate immune systems. This article reviews current knowledge relating to the induction and manifestation of stress protein-related immunological responses that are pertinent to the development and maintenance of protective anti-tumor immunity.

Radiation-induced stress proteins - the role of heat shock proteins (HSP) in anti- tumor responses

Together with surgery and chemotherapy, ionizing irradiation is one of the key therapeutic approaches to treat cancer. More than 50 percent of all cancer patients will receive radiotherapeutic intervention at some stage of their disease. The more precise instrumentation for delivery of radiotherapy and the emphasis on hypofractionation technologies have drastically improved loco-regional tumor control within the last decades. However, the appearance of distant metastases often requires additional systemic treatment modalities such as chemotherapy. High dose chemotherapy is generally considered as immunosuppressive and can cause severe adverse effects. Therefore, we want to elucidate the effects of ionizing irradiation on the immune system and provide immunological treatment strategies which are induced by the host's stress response. Similar to other stressors, ionizing irradiation is known to enhance the synthesis of a variety of immune-stimulatory and -modulating molecules such as heat shock proteins (HSP), high mobility group box 1 (HMGB1) and survivin. Herein, we focus on HSP that exhibit an unusual cell membrane localization and release mechanism in tumor cells. These tumor-specific characteristics render HSP as ideal targets for therapeutic interventions. Depending on their intra/membrane and extracellular localization HSP have the ability to protect tumor cells from stress-induced lethal damage by interfering with antiapoptotic pathways or to elicit anti-cancer immunity.

Induction and repair of DNA double-strand breaks assessed by gamma-H2AX foci after irradiation with pulsed or continuous proton beams

In particle tumor therapy including beam scanning at accelerators, the dose per voxel is delivered within about 100 ms. In contrast, the new technology of laser plasma acceleration will produce ultimately shorter particle packages that deliver the dose within a nanosecond. Here, possible differences for relative biological effectiveness in creating DNA double-strand breaks in pulsed or continuous irradiation mode are studied. HeLa cells were irradiated with 1 or 5 Gy of 20-MeV protons at the Munich tandem accelerator, either at continuous mode (100 ms), or applying a single pulse of 1-ns duration. Cells were fixed 1 h after 1-Gy irradiation and 24 h after 5-Gy irradiation, respectively. A dose-effect curve based on five doses of X-rays was taken as reference. The total number of phosphorylated histone H2AX (gamma-H2AX) foci per cell was determined using a custom-made software macro for gamma-H2AX foci counting. For 1 h after 1-Gy 20-MeV proton exposures, values for the relative biological effectiveness (RBE) of 0.97 ± 0.19 for pulsed and 1.13 ± 0.21 for continuous irradiations were obtained in the first experiment 1.13 ± 0.09 and 1.16 ± 0.09 in the second experiment. After 5 Gy and 24 h, RBE values of 0.99 ± 0.29 and 0.91 ± 0.23 were calculated, respectively. Based on the gamma-H2AX foci numbers obtained, no significant differences in RBE between pulsed and continuous proton irradiation in HeLa cells were detected. These results are well in line with our data on micronucleus induction in HeLa cells.

Interleukin-10 promotes NK cell killing of autologous macrophages by stimulating expression of NKG2D ligands

Under inflammatory conditions, the pleiotropic cytokine interleukin-10 (IL-10) is released in many tissues. It mediates anti-inflammatory effects in particular by inhibiting the release of T helper type 1 (Th1) cytokines. In contrast, we show here that NK cell cytotoxicity against autologous macrophages is elevated if both cell types are cultured with IL-10. The expression of most activatory NK receptors is increased after culture in the presence of IL-10. On the other hand, macrophages cultured in the presence of IL-10 show elevated expression of the NKG2D ligands major histocompatibility complex (MHC) class 1-like molecules (MIC) - A and - B, as well as UL-16 binding proteins (ULBP) - ULBP-1, ULBP-2 and ULBP-3. By masking the interaction of NK cells with macrophages through interruption of the NKG2D receptor with its ligands, we could reverse the IL-10-induced lysis of macrophages. Our data therefore reveal that IL-10 may exert a novel immunomodulatory role by stimulating NKG2D ligand expression on macrophages, thereby rendering them susceptible to NK cell elimination. This suggests that NK cells would delete macrophages and potentially other immature antigen-presenting cells (APC) or their precursors under inflammatory conditions as a feedback mechanism to shut off uncontrolled immune responses.

Noradrenaline increases the expression and release of Hsp72 by human neutrophils

The blood concentration of extracellular 72kDa heat shock protein (eHsp72) increases under conditions of stress, including intense exercise. However, the signal(s), source(s), and secretory pathways in its release into the bloodstream have yet to be clarified. The aim of the present study was to evaluate the role of noradrenaline (NA) as a stress signal on the expression and release of Hsp72 by circulating neutrophils (as a source), all within a context of the immunophysiological regulation during exercise-induced stress in sedentary and healthy young (21-26years) women. The expression of Hsp72 on the surface of isolated neutrophils was determined by flow cytometry, and its release by cultured isolated neutrophils was determined by ELISA. Incubation with cmHsp70-FITC showed that neutrophils express Hsp72 on their surface under basal conditions. In addition, cultured isolated neutrophils (37 degrees C and 5% CO(2)) also released Hsp72 under basal conditions, with this release increasing from 10min to 24h in the absence of cell damage. NA at 10(-9)-10(-5)M doubled the percentage of neutrophils expressing Hsp72 after 60min and 24h incubation. NA also stimulated (by about 20%) the release of Hsp72 after 10min of incubation.

IN CONCLUSION

(1) Hsp72 is expressed on the surface of isolated neutrophils under basal conditions, and this expression is augmented by NA. (2) Isolated neutrophils can also release Hsp72 under cultured basal conditions in the absence of cell death, and NA can increase this release. These results may contribute to confirming the hypothesis that NA can act as a "stress signal" for the increased eHsp72 in the context of exercise stress, with a role for neutrophils as a source for the expression and, to a lesser degree, the release of Hsp72 after activation by NA.

NKG2D-dependent effector function of bronchial epithelium-activated alloreactive T-cells

Allogeneic haematopoietic stem cell transplantation (SCT) has emerged as a curative therapeutic option. However, the role of graft-versus-host disease in lung injury after SCT has yet to be determined. In the present study, primary bronchial epithelial cells and the bronchial epithelial cell line BEAS-2B were used to investigate immune responses of allogeneic CD8+ T-cells directed against respiratory epithelial cells. Following stimulation with irradiated bronchial epithelial cells, CD8+ T-cells produced significant amounts of interferon-gamma, upregulated alloantigen activation markers and proliferated highly compared with T-cells stimulated with interleukin-2 alone. Furthermore, cytotoxicity assays demonstrated that bronchial epithelial cell-specific and granzyme B-mediated cytolytic activity was induced in CD8+ T-cells. Generation of natural killer (NK) T-cells, NK-like T-cells, cytokine-induced killer cells or lymphokine-activated killer cells could be excluded by phenotyping, culture conditions and neglectable lytic activity following stimulation with interleukin-2 alone. Inhibition experiments showed that lysis of bronchial epithelial cells was not major histocompatibility complex-I restricted, but depended on NK group 2 member D signalling; a stimulatory receptor initially shown to be expressed on NK cells. The present data imply that the respiratory epithelium has an antigen presenting function and directly alloactivates cytotoxic CD8+ T-cells that show nonclassical effector function.

Heat shock protein 70 membrane expression on fibroblast-like synovial cells derived from synovial tissue of patients with rheumatoid and juvenile idiopathic arthritis

OBJECTIVE

To screen fibroblast-like synovial cells derived from synovial tissue of rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) patients for the membrane expression of the heat shock protein Hsp70.

METHODS

We performed flow cytometric (fluorescence-activated cell sorting, or FACS) analysis on fibroblast-like synovial cells of 15 RA patients and three JIA patients to investigate Hsp70 membrane expression. Skin fibroblasts derived from the operation wound (n = 4) and peripheral blood mononuclear cells (PBMC) of seven RA and three JIA patients were also tested. Peripheral blood lymphocytes (PBL) and skin fibroblasts of 10 healthy individuals were used as negative controls.

RESULTS

A significantly higher percentage of Hsp70 membrane expression was found on fibroblast-like synovial cells derived from arthritis-affected joints in RA patients (mean 47.7%) when compared with autologous skin fibroblasts (mean 9.5%, p < 0.001) and control skin fibroblasts (mean 5.6%, p < 0.001) or autologous PBL (mean CD45/Hsp70-positive 10.4%, p < 0.001) and control PBL (mean CD45/Hsp70-positive 7.7%, p < 0.001). A high percentage of Hsp70 membrane expression was also observed on fibroblast-like synovial cells derived from three patients with JIA (mean 35.2%) when compared with autologous PBL (mean CD45/Hsp70-positive 10.4%). Synovial cells derived from non-affected joints in a patient with RA who underwent synovectomy for trauma showed low expression of Hsp70 (10.9%).

CONCLUSION

Fibroblast-like synovial cells derived from patients with severe course of RA and JIA are strongly positive for membrane-expressed Hsp70.