Mitogenesis in human lymphocytes following brief exposure to hyperthermia

Combined Photothermal Therapy and Cancer Immunotherapy by Immunogenic Hollow Mesoporous Silicon-Shelled Gold Nanorods

Hyperthermia can be integrated with tumor-killing chemotherapy, radiotherapy and immunotherapy to give rise to an anti-tumor response. To this end, a nano-delivery system is built, which can connect hyperthermia and immunotherapy. On this basis, the impact of such a combination on the immune function of dendritic cells (DCs) is explored. The core of this system is the photothermal material gold nanorod (GNR), and its surface is covered with a silica shell. Additionally, it also forms a hollow mesoporous structure using the thermal etching approach, followed by modification of targeted molecule folic acid (FA) on its surface, and eventually forms a hollow mesoporous silica gold nanorod (GNR@void@mSiO2) modified by FA. GNR@void@mSiO2-PEG-FA (GVS-FA) performs well in photothermal properties, drug carriage and release and tumor targeting performance. Furthermore, the thermotherapy of tumor cells through in vitro NIR irradiation can directly kill tumor cells by inhibiting proliferation and inducing apoptosis. GVS-FA loaded with imiquimod (R837) can be used as a adjuvant to enhance the immune function of DCs through hyperthermia.

DNA damage response and apoptosis induced by hyperthermia in human umbilical cord blood lymphocytes

While hyperthermia (HT) is a promising modality for cancer treatment, the knowledge on mechanisms of its effect on cells is still limited. We have investigated DNA double-strand break (DSB) and apoptosis induced by HT. Umbilical cord blood lymphocytes (UCBL) were subjected to HT at 43 °C. We have treated cells for 1 h (1 h HT), 2 h (2 h HT) and by combined HT and ice treatment (both lasting 1 h). Enumeration of DSB by 53BP1/γH2AX DNA repair focus formation and early apoptosis by γH2AX pan-staining was conducted by automated fluorescent microscopy. Apoptotic stages and viability were assessed by the annexin/propidium iodide (PI) assay using flow cytometry 0, 18, and 42 h post-treatment. HT induced either immediate (2 h HT) or postponed (1 h HT) DNA damage. The levels of 53BP1 and γH2AX foci differed under the same treatment conditions, suggesting that the ratio of co-localized γH2AX/53BP1 foci to all γH2AX and also to all 53BP1 foci could be a valuable marker. The ratio of co-localized foci increased immediately after 2 h HT regardless the way of assessment. For the first time we show, by both annexin/PI and γH2AX pan-staining assay that apoptosis can be induced during or immediately after the 2 h HT treatment. Our results suggest that HT may induce DSB in dependence on treatment duration and post-treatment time due to inhibition of DNA repair pathways and that HT-induced apoptosis might be dependent or associated with DSB formation in human lymphocytes. Assessment of γH2AX pan-staining in lymphocytes affected by HT may represent a valuable marker of HT treatment side effects.

Old and new facts about hyperthermia-induced modulations of the immune system

Hyperthermia (HT) is a potent sensitiser for radiotherapy (RT) and chemotherapy (CT) and has been proven to modulate directly or indirectly cells of the innate and adaptive immune system. We will focus in this article on how anti-tumour immunity can be induced by HT. In contrast to some in vitro assays, in vivo examinations showed that natural killer cells and phagocytes like granulocytes are directly activated against the tumour by HT. Since heat also activates dendritic cells (DCs), HT should be combined with further death stimuli (RT, CT or immune therapy) to allocate tumour antigen, derived from, for example, necrotic tumour cells, for uptake by DCs. We will outline that induction of immunogenic tumour cells and direct tumour cell killing by HT in combination with other therapies contributes to immune activation against the tumour. Studies will be presented showing that non-beneficial effects of HT on immune cells are mostly timely restricted. A special focus is set on immune activation mediated by extracellular present heat shock proteins (HSPs) carrying tumour antigens and further danger signals released by dying tumour cells. Local HT treatment in addition to further stress stimuli exerts abscopal effects and might be considered as in situ tumour vaccination. An increased natural killer (NK) cell activity, lymphocyte infiltration and HSP-mediated induction of immunogenic tumour cells have been observed in patients. Treatments with the addition of HT therefore can be considered as a personalised cancer treatment approach by specifically activating the immune system against the individual unique tumour.

Effect of ex vivo hyperthermia on radiation-induced micronuclei in lymphocytes of cancer patients before and during radiotherapy

To investigate the effect of ex vivo hyperthermia (HT) and 137Cs-irradiation on micronucleus (MN) production in cytokinesis-blocked lymphocytes, we obtained the peripheral blood samples from the same cancer patients (n=6) before and during fractionated partial-body radiotherapy (xRT). The whole blood cultures were heated at 43.5 degrees C for 60 min, followed by 137Cs irradiation (0-4 Gy). The control cultures from the same patients were incubated at 37 degreesC after being exposed to radiation. The lymphocytes were then stimulated with PHA. Cytochalasin B was applied at 44 h, and lymphocytes were harvested at 72 h. MN frequency was determined on Giemsa-stained slides. We found that in patients before xRT, HT (43.5 degrees C) significantly increased the MN yield (mean+/-SEM) in unirradiated lymphocytes from 15.6+/-2.8 (37 degrees C) to 39.7+/-10.9. Further, in patients either before or during xRT, when the lymphocytes were treated with HT (43.5 degrees C) and combined with ex vivo irradiation, the MN yield (Y) could be estimated by a linear equation Y=C+alphaD. Our findings indicate that as measured by the MN production in cytokinesis-blocked lymphocytes, HT alone at 43.5 degrees C++ induced DNA damage. Moreover, it enhanced the radiation-induced cytogenetic damage. Therefore, the application of HT may impair the T-cell function in cancer patients who are receiving radiotherapy. 1998 Elsevier Science B.V.

Radiant heat-induced hyperthermia in mice: in vivo effects on the immune system

Whole-body hyperthermia (WBH) in mice was induced by 2-4-h exposure to radiant heat resulting in core body temperatures of 38.5-40.4 degrees C, and correlated directly with the magnitude and duration of heat treatment. Two-hour heat treatments in this temperature range did not consistently affect generation of antibody-forming cells in vivo, while 4-h treatments at temperatures greater than or equal to 40 degrees C significantly suppressed the antibody-forming cell response. The capacity of lymphocytes from similarly heated mice to generate antibody-forming cells in vitro was not affected, suggesting that the observed in vivo suppression may be mediated by circulating factors rather than by some heat-induced alteration in the cells themselves. In vivo treatment did not alter T-cell responsiveness to the mitogen Con-A or delayed-type hypersensitivity responses to sheep red blood cells. Quantitative and flow cytometric assessment of splenic and thymic lymphocyte numbers showed that WBH did not alter absolute numbers of lymphocytes but did temporarily change the proportions of lymphocyte subsets. An immediate increase in splenic L3T4+ cells was observed, followed within 18 h by an overall decrease in Lyt 2+ and Thy 1.2+ T-cells. In the thymus the percentages of mature T cells increased. In general, only minimal effects of heat on the immune responses of normal mice could be demonstrated.

Hyperthermic effects on viability and growth kinetics of human lymphoblastoid cells

During clinical hyperthermia, various blood elements may be exposed to elevated temperatures. The effect of heat on human lymphocyte viability and human lymphoblastoid cell viability and growth was therefore measured. In the viability studies, cells were heated for different times and temperatures and stained with fluorescein diacetate either immediately of at various times after treatment; dye uptake was then analysed using fluorescence microscopy. There was no significant decrease in lymphocyte viability when assayed at 0 and 24 h after heating at 42-43 degrees C for varying times. Similarly, when proliferating lymphoblastoid cells were heated at 42-43 degrees C, there was no decrease measured in viability immediately after heating. However, in contrast to the lymphocyte results, a progressive decrease of lymphoblastoid cell viability was observed with increasing time after treatment. A nadir in viability was observed 48-72 h after heating, followed by a subsequent apparent recovery. This recovery showed a correlation with cell growth, as well as lysis of non-viable cells. The cell population doubling time was also lengthened, with longer doubling times observed for more severe heat treatments.