Heat shock proteins, tumor immunogenicity and antigen presentation: an integrated view

Hyperthermia in Combination with Emerging Targeted and Immunotherapies as a New Approach in Cancer Treatment

Despite significant advancements in the development of novel therapies, cancer continues to stand as a prominent global cause of death. In many cases, the cornerstone of standard-of-care therapy consists of chemotherapy (CT), radiotherapy (RT), or a combination of both. Notably, hyperthermia (HT), which has been in clinical use in the last four decades, has proven to enhance the effectiveness of CT and RT, owing to its recognized potency as a sensitizer. Furthermore, HT exerts effects on all steps of the cancer-immunity cycle and exerts a significant impact on key oncogenic pathways. Most recently, there has been a noticeable expansion of cancer research related to treatment options involving immunotherapy (IT) and targeted therapy (TT), a trend also visible in the research and development pipelines of pharmaceutical companies. However, the potential results arising from the combination of these innovative therapeutic approaches with HT remain largely unexplored. Therefore, this review aims to explore the oncology pipelines of major pharmaceutical companies, with the primary objective of identifying the principal targets of forthcoming therapies that have the potential to be advantageous for patients by specifically targeting molecular pathways involved in HT. The ultimate goal of this review is to pave the way for future research initiatives and clinical trials that harness the synergy between emerging IT and TT medications when used in conjunction with HT.

Vanillic Acid Improves Stress Resistance and Substantially Extends Life Span in Caenorhabditis elegans

Aging is the root cause of several pathologies like neurological and cardiovascular diseases. Identifying compounds that improve health span and extend life span, called geroprotectors, could be crucial to preventing or at least delaying the onset of age-related diseases. In this regard, the nematode Caenorhabditis elegans (C. elegans) is emerging as an easy, efficient, low-cost model system to screen natural products and identify novel geroprotectors. Phenolic acids can be found in a wide range of natural products that are part of the human diet. Vanillic acid (VA) is a phenolic acid that has previously been attributed with antioxidant, anti-inflammatory, and neuroprotective features. To determine whether these beneficial health effects amount to an extension of health span and life span, in this work, we thoroughly explore the effect of VA on C. elegans stress resistance and life span. We found that VA increases thermotolerance (19.4%), reduces protein aggregation (between 30% and 40%), improves motility, and extends life span by almost 50%, an extent hardly ever achieved with a natural compound. The increased thermotolerance induced by VA is independent of the insulin/insulin-like growth factor-1 signaling pathway but requires heat shock factor-1 and is associated with increased heat shock protein-4 (HSP-4) and hsp-16.2 expression. These results provide new insight into understanding the therapeutical properties of VA and warrant further investigation of VA as a novel geroprotector.

HSP70 Expression Signature in Renal Cell Carcinoma: A Clinical and Bioinformatic Analysis Approach

Heat shock proteins (HSPs) are cytoprotective against stressful conditions, as in the case of cancer cell metabolism. Scientists proposed that HSP70 might be implicated in increased cancer cell survival. This study aimed to investigate the HSP70 (HSPA4) gene expression signature in patients with renal cell carcinoma (RCC) in correlation to cancer subtype, stage, grade, and recurrence, combining both clinicopathological and in silico analysis approaches. One hundred and thirty archived formalin-fixed paraffin-embedded samples, including 65 RCC tissue specimens and their paired non-cancerous tissues, were included in the study. Total RNA was extracted from each sample and analyzed using TaqMan quantitative Real-Time Polymerase Chain Reaction. Correlation and validation to the available clinicopathological data and results were executed. Upregulated HSP70 (HSPA4) gene expression was evident in RCC compared to non-cancer tissues in the studied cohort and was validated by in silico analysis. Furthermore, HSP70 expression levels showed significant positive correlations with cancer size, grade, and capsule infiltration, as well as recurrence in RCC patients. The expression levels negatively correlated with the overall survival (r = -0.87, p < 0.001). Kaplan-Meier curves showed lower survival rates in high HSP70 expressor group compared to the low expressors. In conclusion, the HSP70 expression levels are associated with poor RCC prognosis in terms of advanced grade, capsule infiltration, recurrence, and short survival.

Expression Analysis of Molecular Chaperones Hsp70 and Hsp90 on Development and Metabolism of Different Organs and Testis in Cattle (Cattle-yak and Yak)

Hsp70 and Hsp90 play an important role in testis development and spermatogenesis regulation, but the exact connection between Hsp70 and Hsp90 and metabolic stress in cattle is unclear. Here, we focused on the male cattle−yak and yak, investigated the expression and localization of Hsp70 and Hsp90 in their tissues, and explored the influence of these factors on development and metabolism. In our study, a total of 54 cattle (24 cattle−yaks and 30 yaks; aged 1 day to 10 years) were examined. The Hsp90 mRNA of the cattle−yak was first cloned and compared with that of the yak, and variation in the amino acid sequence was found, which led to differences in protein spatial structure. Using real-time quantitative PCR (RT-qPCR) and Western blot (WB) techniques, we investigated whether the expression of Hsp70 and Hsp90 mRNA and protein are different in the cattle−yak and yak. We found a disparity in Hsp70 and Hsp90 mRNA and protein expression in different non-reproductive organs and in testicular tissues at different stages of development, while high expression was observed in the testes of both juveniles and adults. Moreover, it was intriguing to observe that Hsp70 expression was significantly high in the yak, whereas Hsp90 was high in the cattle−yak (p < 0.01). We also examined the location of Hsp70 and Hsp90 in the testis by immunohistochemical (IHC) and immunofluorescence (IF) techniques, and the results showed that Hsp70 and Hsp90 were positive in the epithelial cells, spermatogenic cells, and mesenchymal cells. In summary, our study proved that Hsp70 and Hsp90 expressions were different in different tissues (kidney, heart, cerebellum, liver, lung, spleen, and testis), and Hsp90 expression was high in the testis of the cattle−yak, suggesting that dysplasia of the cattle−yak may correlate with an over-metabolism of Hsp90.

The Role of Photodynamic Therapy in Triggering Cell Death and Facilitating Antitumor Immunology

Cancer is a major threat to human health because of its high mortality, easy recurrence, strong invasion, and metastasis. Photodynamic therapy (PDT) is a promising minimally invasive treatment for tumor. Compared with traditional treatment methods, PDT is less invasive and does not easily damage normal tissues. Most of the effects of this treatment are due to the direct effects of singlet oxygen together with reactive oxygen species. PDT can provide the source of active oxygen for the Fenton reaction, which enhances ferroptosis and also improves the efficacy of PDT in antitumor therapy. Additionally, in contrast to chemotherapy and radiotherapy, PDT has the effect of stimulating the immune response, which can effectively induce immunogenic cell death (ICD) and stimulate immunity. PDT is an ideal minimally invasive treatment method for tumors. In this paper, according to the characteristics of anti-tumor immunity of PDT, some tumor treatment strategies of PDT combined with anti-tumor immunotherapy are reviewed.

Immunosurveillance of cancer cell stress

Cancer development is tightly controlled by effector immune responses that recognize and eliminate malignantly transformed cells. Nonetheless, certain immune subsets, such as tumor-associated macrophages, have been described to promote tumor growth, unraveling a double-edge role of the immune system in cancer. Cell stress can modulate the crosstalk between immune cells and tumor cells, reshaping tumor immunogenicity and/or immune function and phenotype. Infiltrating immune cells are exposed to the challenging conditions typically present in the tumor microenvironment. In return, the myriad of signaling pathways activated in response to stress conditions may tip the balance toward stimulation of antitumor responses or immune-mediated tumor progression. Here, we explore how distinct situations of cellular stress influence innate and adaptive immunity and the consequent impact on cancer establishment and progression.

Proteomic analysis of the response of porcine adrenal gland to heat stress

Heat stress (HS) and its associated pathologies are major challenges facing the pig industry in southern China, and are responsible for large economic losses. However, the molecular mechanisms governing the abnormal secretion of HS-responsive hormones, such as glucocorticoids, are not fully understood. The goal of this study was to investigate differentially expressed proteins (DEPs) in the adrenal glands of pigs, and to elucidate changes in the immune neuroendocrine system in pigs following HS. Through a functional proteomics approach, we identified 1202 peptides, corresponding to 415 proteins. Of these, we found 226 DEPs between heat-stressed and control porcine adrenal gland tissue; 99 of these were up-regulated and 127 were down-regulated in response to HS. These DEPs included proteins involved in substrate transport, cytoskeletal changes, and stress responses. Ingenuity Pathway Analysis was used to identify the subcellular characterization, functional pathway involvement, regulatory networks, and upstream regulators of the identified proteins. Functional network and pathway analyses may provide insights into the complexity and dynamics of HS-host interactions, and may accelerate our understanding of the mechanisms of HS.

Effect of embryonic thermal manipulation on heat shock protein 70 expression and immune system development in Pekin duck embryos

Two experiments were conducted to study the effects of thermal manipulation on heat shock protein 70 (HSP70) transcription and immune cell characteristics' in Pekin duck embryos. In experiments I and II, fertile duck eggs were incubated at either a standard (S; 37°C) or high (H; 38.0°C) temperature from embryonic day (ED) 1 to 10. At ED11, half the eggs incubated at 37.5°C or 38.0°C were either kept at 37.5°C (SS) or 38.0°C (HH) respectively, or moved to the opposite incubator/temperature of either 38.0°C (SH) or 37.5°C (HS). Beginning on ED 21, all eggs (embryos) were incubated at 37.5°C. In experiments I and II, the mean egg shell temperature (EST) of eggs incubated at 38.0°C was higher than that from 37.5°C at ED10 (P < 0.01). In both experiments, the yolk free wet embryo body weight (YFWEBW) of embryos from the HS treatment was increased while that in the HH treatments was decreased compared with the SS treatment at ED25 (P < 0.01). In experiment II, embryos from the HH treatment had increased HSP70 mRNA compared with the SS treatment in the liver, thymus, and bursa (P < 0.05). The thymus and bursa from embryos in the SH treatment had increased MHCI mRNA when compared with the SS treatment (P < 0.05). The thymus from HH and SH treatments had increased MHCII mRNA while the bursa from the HH and SH treatments had decreased MHCII mRNA when compared with the SS treatment (P < 0.05). The spleen and bursa from the HH treatment had increased IL-6, IFNγ, and IL-10 mRNA when compared with the SS treatment (P < 0.05). The thymus and spleen from embryos in the HH treatment had increased CD8+/CD4+ ratios and CD4+CD25+ cell percentages compared with the SS treatment (P < 0.05). In conclusion, embryos incubated at 0.5°C higher than the standard incubation temperature from ED1 to 21 had increased HSP70 mRNA, MHCI, and inflammatory cytokines, and the immune response was skewed toward cell-mediated immunity.

Immunological considerations underlying heat shock protein-mediated cancer vaccine strategies

The success of active immunotherapies in the prevention of many infectious diseases over the course of over 200 years has lead scientists to wonder if the same principles could be applied to cancer. Antigen-specific active immunotherapies for the treatment of cancer have been researched for over two decades, however, the overwhelming majority of these studies have failed to stimulate robust clinical responses. It is clear that current active immunotherapy research should incorporate methods to increase the immunostimulatory capacity of these therapies. To directly address this need, we propose the addition of the immunostimulatory heat shock proteins (HSPs) to active immunotherapeutic strategies to augment their efficacy. Heat shock proteins are a family of highly conserved intracellular chaperone proteins, and are the most abundant family proteins inside cells. This ubiquity, and their robust immunostimulatory capacity, points to their importance in regulation of intracellular processes and, therefore, indicators of loss of cellular integrity if found extracellularly. Thus, we emphasize the importance of taking into consideration the location of vaccine-derived HSP/tumor-antigen complexes when designing active immunotheraputic strategies.

Cloning of HSP90, expression and localization of HSP70/90 in different tissues including lactating/non-lactating yak (Bos grunniens) breast tissue

The aim of this study is to investigate the expression and localization of HSP70/90 in different tissues and explore the regulation effects of HSP70/90 at lactation period of female yaks. HSP90 mRNA was cloned from the heart samples of female yaks, Quantitative real-time (qRT-PCR), Western blotting (WB), immunohistochemistry and immunofluorescence assays were utilized to analyze the expressions of HSP70/90 mRNA and protein in different tissues. Sequence analysis showed that HSP90 is a conserved molecular chaperone of female yaks. The qRT-PCR, WB results showed that the expressions of HSP70/90 mRNA and protein were significantly different in different tissues, and 3-fold higher expression during the lactation period than the non-lactation period of breast tissue (P < 0.01). Immunohistochemistry and immunofluorescence assays results showed that HSP70/90 were located in the cardiac muscle cells, cerebellar medulla, theca cells lining at the reproductive system, and the mammary epithelia of the breasts. In addition, the expression level of HSP70 was higher than those of HSP90 in all examined tissues. Therefore, our results strongly suggest that the expression and localization of HSP70/90 could provide significant evidence to further research in tissue specific expression, and lactation function of female yaks.

Rationale of hyperthermia for radio(chemo)therapy and immune responses in patients with bladder cancer: Biological concepts, clinical data, interdisciplinary treatment decisions and biological tumour imaging

Bladder cancer, the most common tumour of the urinary tract, ranks fifth among all tumour entities. While local treatment or intravesical instillation of bacillus Calmette-Guerin (BCG) provides a treatment option for non-muscle invasive bladder cancer of low grade, surgery or radio(chemo)therapy (RT) are frequently applied in high grade tumours. It remains a matter of debate whether surgery or RT is superior with respect to clinical outcome and quality of life. Surgical resection of bladder cancer can be limited by acute side effects, whereas, RT, which offers a non-invasive treatment option with organ- and functional conservation, can cause long-term side effects. Bladder toxicity by RT mainly depends on the total irradiation dose, fraction size and tumour volume. Therefore, novel approaches are needed to improve clinical outcome. Local tumour hyperthermia is currently used either as an ablation therapy or in combination with RT to enhance anti-tumour effects. In combination with RT an increase of the temperature in the bladder stimulates the local blood flow and as a result can improve the oxygenation state of the tumour, which in turn enhances radiation-induced DNA damage and drug toxicity. Hyperthermia at high temperatures can also directly kill cells, particularly in tumour areas which are poorly perfused, hypoxic or have a low tissue pH. This review summarises current knowledge relating to the role of hyperthermia in RT to treat bladder cancer, the induction and manifestation of immunological responses induced by hyperthermia, and the utilisation of the stress proteins as tumour-specific targets for tumour detection and monitoring of therapeutic outcome.

Bacterial membranes enhance the immunogenicity and protective capacity of the surface exposed tick Subolesin-Anaplasma marginale MSP1a chimeric antigen

Ticks are vectors of diseases that affect humans and animals worldwide. Tick vaccines have been proposed as a cost-effective and environmentally sound alternative for tick control. Recently, the Rhipicephalus microplus Subolesin (SUB)-Anaplasma marginale MSP1a chimeric antigen was produced in Escherichia coli as membrane-bound and exposed protein and used to protect vaccinated cattle against tick infestations. In this research, lipidomics and proteomics characterization of the E. coli membrane-bound SUB-MSP1a antigen showed the presence of components with potential adjuvant effect. Furthermore, vaccination with membrane-free SUB-MSP1a and bacterial membranes containing SUB-MSP1a showed that bacterial membranes enhance the immunogenicity of the SUB-MSP1a antigen in animal models. R. microplus female ticks were capillary-fed with sera from pigs orally immunized with membrane-free SUB, membrane bound SUB-MSP1a and saline control. Ticks ingested antibodies added to the blood meal and the effect of these antibodies on reduction of tick weight was shown for membrane bound SUB-MSP1a but not SUB when compared to control. Using the simple and cost-effective process developed for the purification of membrane-bound SUB-MSP1a, endotoxin levels were within limits accepted for recombinant vaccines. These results provide further support for the development of tick vaccines using E. coli membranes exposing chimeric antigens such as SUB-MSP1a.

Positive or negative involvement of heat shock proteins in multiple sclerosis pathogenesis: an overview

Multiple sclerosis (MS) is the most diffuse chronic inflammatory disease of the central nervous system. Both immune-mediated and neurodegenerative processes apparently play roles in the pathogenesis of this disease. Heat shock proteins (HSPs) are a family of highly evolutionarily conserved proteins; their expression in the nervous system is induced in a variety of pathologic states, including cerebral ischemia, neurodegenerative diseases, epilepsy, and trauma. To date, investigators have observed protective effects of HSPs in a variety of brain disease models (e.g. of Alzheimer disease and Parkinson disease). In contrast, unequivocal data have been obtained for their roles in MS that depend on the HSP family and particularly on their localization (i.e. intracellular or extracellular). This article reviews our current understanding of the involvement of the principal HSP families in MS.

Abscopal antitumor immune effects of magnet-mediated hyperthermia at a high therapeutic temperature on Walker-256 carcinosarcomas in rats

The abscopal effect has previously been described in various tumors and is associated with radiation therapy and hyperthermia, with possible underlying mechanisms explaining each observed case. In the present study, we aimed to investigate the antitumor effects of magnet-mediated hyperthermia on Walker-256 carcinosarcomas in rats at two different temperature ranges (42–46°C and 50–55°C). We also aimed to identify whether a higher therapeutic temperature of magnetic-mediated hyperthermia improves the abscopal antitumor effects, where localised irradiation of the tumor causes not only the irradiated tumor to shrink, but also tumors located far from the area of irradiation. Following induction of carcinosarcoma in both sides of the body, magnet-mediated hyperthermia was applied to one side only, leaving the other side as a control. The changes in tumor growth were observed. Our results demonstrated that magnet-mediated hyperthermia at a higher temperature inhibited the growth of carcinosarcoma at the site of treatment. Furthermore, the growth of the carcinosarcoma on the untreated side was also inhibited. The expression levels of proliferating cell nuclear antigen were decreased in the hyperthermia group, which was more significant in the higher temperature test group. Flow cytometric analysis showed an increased number of CD4- and CD8-positive T cells, and enzyme-linked immunosorbent assay showed increased levels of interferon-γ and interleukin-2 in the higher temperature group. These results suggested that magnet-mediated hyperthermia at a higher temperature (50–55°C) can improve the abscopal antitumor effects and stimulate a greater endogenous immune response in carcinosarcoma-bearing rats.

Hyperthermia on skin immune system and its application in the treatment of human papillomavirus-infected skin diseases

Hyperthermia is a condition characterized by increased body temperature as a consequence of failed thermoregulation. Hyperthermia occurs when a body produces or absorbs more heat than it dissipates. Hyperthermia also elicits various effects on the physiology of living cells. For instance, fever-range temperature (39°C to 40°C) can modulate the activities of immune cells, including antigen-presenting cells, Tcells, and natural killer cells. Heat shock temperature (41°C to 43°C) can increase the immunogenicity of tumor cells. Cytotoxic temperature (> 43°C) can create an antigen source to induce an anti-tumor immune response. The immunomodulatory effect of hyperthermia has promoted an interest in hyperthermia-aided immunotherapy, particularly against tumors. Hyperthermia has also been used to treat deep fungal, bacterial, and viral skin infections. We conducted a series of open or controlled trials to treat skin human papillomavirus infection by inducing local hyperthermia. More than half of the patients were significantly cured compared with those in the control trial. A series of challenging clinical cases, such as large lesions in pregnant patients or patients with diabetes mellitus, were also successfully and safely managed using the proposed method. However, further studies should be conducted to clarify the underlying mechanisms and promote the clinical applications of hyperthermia.

Prognostic significance of heat shock proteins in urothelial carcinoma of the urinary bladder

AIMS

Heat shock proteins (HSPs) are a group of molecules induced by a variety of environmental and pathophysiological stresses, including cancer. The expression of HSPs has been implicated in the regulation of apoptosis and immunity in neoplasia. The purpose of this study was to evaluate the expression and clinicopathological relevance of several HSPs in urothelial carcinomas of the urinary bladder.

METHODS AND RESULTS

Immunohistochemical staining for HSP27, HSP60, HSP70 and HSP90 was performed on samples collected from 744 clinical cases. The results were correlated with clinicopathological characteristics using univariate and multivariate analyses. High expression of HSP70 predicted recurrence of non-muscle-invasive urothelial carcinoma treated by transurethral resection, and low expression of HSP27 correlated with progression and cancer-specific mortality for non-muscle-invasive cancers treated by transurethral resection. Low expression of HSP27 also predicted cancer-specific mortality for patients who underwent cystectomy.

CONCLUSIONS

Both HSP27 and HSP70 impact on the biological behaviour of urothelial carcinomas of the urinary bladder. Immunohistochemical assessment of HSPs can provide useful prognostic information that could ultimately help to develop individualized surveillance programmes.

Radio frequency induced hyperthermia mediated by dextran stabilized LSMO nanoparticles: in vitro evaluation of heat shock protein response

Dextran stabilized La(0.7)Sr(0.3)MnO(3) (Dex-LSMO) is an alternative cancer hyperthermia agent holding considerable promise. Here, we have carried out a comparative study on radio frequency (~264 kHz) induced Dex-LSMO mediated heating and extraneous heating (mimicking generalized hyperthermia) in terms of changes in the morphology, proliferation pattern and induction of heat shock proteins in a human melanoma cell line (A375). Our results clearly show that the cellular effects seen with extraneous heating (60 min at 43 °C) could be reproduced by just six minutes of radio frequency induced Dex-LSMO mediated heating. More importantly, the observed enhanced levels of HSP 70 and 90 (molecular markers of heat shock that trigger favorable immunological reactions) seen with Dex-LSMO mediated heating were comparable to extraneous heating. These results suggest the possible utility of Dex-LSMO as a cancer hyperthermia agent.

DNA Vaccines for Prostate Cancer

Delivery of plasmid DNA encoding an antigen of interest has been demonstrated to be an effective means of immunization, capable of eliciting antigen-specific T cells. Plasmid DNA vaccines offer advantages over other anti-tumor vaccine approaches in terms of simplicity, manufacturing, and possibly safety. The primary disadvantage is their poor transfection efficiency and subsequent lower immunogenicity relative to other genetic vaccine approaches. However, multiple preclinical models demonstrate anti-tumor efficacy, and many efforts are underway to improve the immunogenicity and anti-tumor effect of these vaccines. Clinical trials using DNA vaccines as treatments for prostate cancer have begun, and to date have demonstrated safety and immunological effect. This review will focus on DNA vaccines as a specific means of antigen delivery, advantages and disadvantages of this type of immunization, previous experience in preclinical models and human trials specifically conducted for the treatment of prostate cancer, and future directions for the application of DNA vaccines to prostate cancer immunotherapy.

Hsp70 and its molecular role in nervous system diseases

Heat shock proteins (HSPs) are induced in response to many injuries including stroke, neurodegenerative disease, epilepsy, and trauma. The overexpression of one HSP in particular, Hsp70, serves a protective role in several different models of nervous system injury, but has also been linked to a deleterious role in some diseases. Hsp70 functions as a chaperone and protects neurons from protein aggregation and toxicity (Parkinson disease, Alzheimer disease, polyglutamine diseases, and amyotrophic lateral sclerosis), protects cells from apoptosis (Parkinson disease), is a stress marker (temporal lobe epilepsy), protects cells from inflammation (cerebral ischemic injury), has an adjuvant role in antigen presentation and is involved in the immune response in autoimmune disease (multiple sclerosis). The worldwide incidence of neurodegenerative diseases is high. As neurodegenerative diseases disproportionately affect older individuals, disease-related morbidity has increased along with the general increase in longevity. An understanding of the underlying mechanisms that lead to neurodegeneration is key to identifying methods of prevention and treatment. Investigators have observed protective effects of HSPs induced by preconditioning, overexpression, or drugs in a variety of models of brain disease. Experimental data suggest that manipulation of the cellular stress response may offer strategies to protect the brain during progression of neurodegenerative disease.

Hsp70: anti-apoptotic and tumorigenic protein

Heat shock protein 70 (Hsp70) is a powerful chaperone whose expression is induced in response to a wide variety of physiological and environmental insults, including anticancer chemotherapy, thus allowing the cell to survive to lethal conditions. Hsp70 cytoprotective properties may be explained by its anti-apoptotic function. Indeed, this protein can inhibit key effectors of the apoptotic machinery at the pre- and postmitochondrial level. In cancer cells, the expression of Hsp70 is abnormally high, and Hsp70 may participate in oncogenesis and in resistance to chemotherapy. In rodent models, Hsp70 overexpression increases tumor growth and metastatic potential. Depletion or inhibition of Hsp70 frequently reduces the size of the tumors and even can cause their complete involution. But Hsp70 can also be found in the extracellular medium. Its role is then immunogenic and the term chaperokine to define the extracellular chaperones has been advanced. Hsp70 tumorigenic functions as well as the strategies that are being developed in cancer therapy in order to inhibit Hsp70 are commented in this chapter.

Tumour infiltrating host cells and their significance for hyperthermia

Much information can be gained by investigating the consequences of hyperthermia on individual cell populations in vitro, however the precise effects of such a therapeutic modality in vivo depend on the tumour microenvironment and the cellular composition therein. Although the direct cytotoxic effects of hyperthermia on tumour tissue can lead to an immediate reduction in tumour volume, long-term benefits to local and distal tumour recurrence will very much depend on the induction of immunity and the capacity of effector cells to traffic to tumours and elicit their cytotoxic functions. The immunological sequelae to hyperthermia are even more important in those instances when large tumour volumes preclude the delivery of appropriate thermal damage. The development of protective anti-tumour immunity requires a plethora of interactions and responses, the vast majority of which can be influenced by temperatures that are consistent with fever-like temperatures (39 degrees -40 degrees C), as well as hyperthermia treatment (<41 degrees C). This article reviews current knowledge relating to the effects of hyperthermia treatment on aspects of the induction and manifestation of immunological responses that are most pertinent to the development and maintenance of protective anti-tumour immunity.

Clinical correlation of circulating heat shock protein 70 in acute leukemia

The heat shock protein 70 (HSP70) is one of the molecular chaperone family involved in the protection of cells upon exposure to various types of stresses. Plasma circulating HSP70 (cHSP70) is believed to play a role in the anti-tumor immune responses and its levels may reflect the levels of severity or the disease condition. Using electrochemiluminescence protein detection immunoassay, we measured the cHSP70 levels in the plasma of patients with acute myeloid leukemia (AML) (n=96), myelodysplastic syndrome (MDS) (n=28), and acute lymphoblastic leukemia (ALL) (n=40) and compared with those in normal individuals (n=99). cHSP70 levels were significantly higher in AML (median: 10.71 ng/mL, range: 1.93-79.0 ng/mL) and ALL (median: 27.59 ng/mL, range: 5.09-129.6 ng/mL) as compared to those in MDS (median: 4.54 ng/mL, range: 1.35-58.3 ng/mL) or healthy controls (median: 4.13 ng/mL, range: 1.75-13.6 ng/mL). Levels of cHSP70 showed significant positive correlation with lactate dehydrogenase (LDH) and white blood cells (WBC) in AML and ALL patients, which may reflect overall tumor load. Furthermore, patients with higher levels of cHSP70 had significantly shorter survival in AML (P=0.04) and ALL (P=0.05), suggesting that in these two acute diseases, cHSP70 is an indicator for poor prognosis. Our data support the potential of using free cHSP70 as a biomarker in leukemias and potentially other types of cancers.

Signaling pathways induced by a tumor-derived vaccine in antigen presenting cells

We have previously reported on the anti-tumoral potential of a chaperone-rich cell lysate (CRCL) vaccine. Immunization with CRCL generated from tumors elicits specific T and NK cell-dependent immune responses leading to protective immunity in numerous mouse tumor models. CRCL provides both a source of tumor antigens and danger signals leading to dendritic cell activation. In humans, tumor-derived CRCL induces dendritic cell activation and CRCL-loaded dendritic cells promote the generation of cytotoxic T lymphocytes in vitro. The current study was designed to identify the signaling events and modifications triggered by CRCL in antigen presenting cells. Our results indicate that tumor-derived CRCL not only promotes the activation of dendritic cells, but also significantly fosters the function of macrophages that thus appear as major targets of this vaccine. Activation of both cell types is associated with the induction of the MAP kinase pathway, the phosphorylation of STAT1, STAT5 and AKT and with transcription factor NF-kappaB activation in vitro and in vivo. These results thus provide important insights into the mechanisms by which CRCL-based vaccines exert their adjuvant effects on antigen presenting cells.

Immunologic response induced by synergistic effect of alternating cooling and heating of breast cancer

In this study, the therapeutic effect and the induced anti-tumor immunity through the alternating cooling and heating was investigated using 4T1 murine mammary carcinoma, a common model of human metastatic breast cancer. While fifteen of seventeen regular mice were cured, primary recurrence and metastasis caused death of all the nude mice within one month after the same treatment. Histological analyses showed that viable cells existed in the tumor debris after the treatment, indicating that the direct killing effect was not the only therapeutic mechanism. Further investigation found rejection of tumor upon re-challenge, and anti-tumor immune response was studied. Stronger cytotoxicity T-lymphocyte (CTL) and Th1 cytokines response as well as infiltration of immunocytes were observed in the treated mice in comparison to those after the surgical resection. The results showed that the alternating cooling and heat could stimulate anti-tumor immunologic response in vivo and the underlying mechanisms will be further investigated in the near future.

Petiveria alliacea extracts uses multiple mechanisms to inhibit growth of human and mouse tumoral cells

BACKGROUND

There is ethnopharmacological evidence that Petiveria alliacea can have antitumor activity; however, the mechanism of its cytotoxic activity is not well understood. We assessed multiple in vitro biological activities of an ethyl acetate soluble plant fraction over several tumor cell lines.

METHODS

Tumor cell lines were evaluated using the following tests: trypan blue exclusion test, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide], flow cytometry, cytoskeleton organization analysis, cell cycle, mitochondria membrane depolarization, clonogenicity test, DNA fragmentation test and differential protein expression by HPLC-Chip/MS analysis. F4 fraction characterization was made by HPLC-MS.

RESULTS

Petiveria alliacea fraction characterized by de-replication was found to alter actin cytoskeleton organization, induce G2 cell cycle arrest and cause apoptotic cell death in a mitochondria independent way. In addition, we found down regulation of cytoskeleton, chaperone, signal transduction proteins, and proteins involved in metabolic pathways. Finally up regulation of proteins involved in translation and intracellular degradation was also observed.

CONCLUSION

The results of this study indicate that Petiveria alliacea exerts multiple biological activities in vitro consistent with cytotoxicity. Further studies in animal models are needed but Petiveria alliacea appears to be a good candidate to be used as an antitumor agent.

Bovine viral diarrhea virus infection affects the expression of proteins related to professional antigen presentation in bovine monocytes

The complete annotation of the cattle genome allows reliable protein identification by tandem mass spectrometry (MS(2)) and greatly facilitates proteomics. Previously, we reported that differential detergent fractionation (DDF) analysis of bovine monocytes reveals proteins related to antigen pattern recognition, uptake and presentation to immunocompetent lymphocytes. Here we have identified 47 bovine proteins, involved in immune function of professional antigen-presenting cells (APC) that have been significantly altered after cytopathic (cp) Bovine Viral Diarrhea Virus (BVDV) infection. In particular, proteins related to immune responses such as cell adhesion, apoptosis, antigen uptake, processing and presentation, acute phase response proteins, MHC class I- and II-related proteins and other molecules involved in immune function of professional antigen presentation have been significantly altered after BVDV infection. Our data suggest that cp BVDV, while promoting monocyte activation and differentiation, is inhibiting their antigen presentation to immunocompetent T cells, thus resulting in the uncontrolled inflammation mediated by activated macrophages, enhanced viral spread, and impaired anti-viral defense mechanisms in the host.

Hyperthermia on immune regulation: a temperature's story

Over the last decade the linkage between hyperthermia, heat shock proteins and fever with the body's immune system has been well investigated. The immunomodulatory function of hyperthermia has been found to be quite sensitively regulated by temperature, as different levels of heating can bring different modulatory effect on different sensitive targets. Understanding these intrinsic mechanisms could bring new inspirations on the design of clinical trials combining local tumor hyperthermia with immunotherapy in cancer patients. This review will attempt to tell the story about the effect of temperature on immune regulation, with special emphasis on the clinical application of hyperthermia and the feasibility of combining it with immunotherapy in the clinic.

Heat shock protein 70 (Hsp70): membrane location, export and immunological relevance

Stress or heat shock proteins (HSPs) are remarkably conserved in all living organisms. Their expression is induced in response to a variety of physiological and environmental insults. In the cytosol these proteins play an essential role as molecular chaperones by assisting the correct folding of nascent and stress-accumulated misfolded proteins, preventing protein aggregation, transport of proteins, and supporting antigen processing and presentation. Following stress, intracellularly located HSPs fulfill protective functions and thus prevent lethal damage. In contrast, membrane-bound or extracellularly located HSPs act as danger signals and elicit immune responses mediated either by the adaptive or innate immune system. Here, HSPs act as carriers for immunogenic peptides, induce cytokine release or provide recognition sites for natural killer (NK) cells. This article will discuss methods for the detection of membrane-bound and extracellular HSPs and methods for determining their immunological functions.

Hsp27 (HspB1) and alphaB-crystallin (HspB5) as therapeutic targets

Hsp27 and alphaB-crystallin are molecular chaperones that are constitutively expressed in several mammalian cells, particularly in pathological conditions. These proteins share functions as diverse as protection against toxicity mediated by aberrantly folded proteins or oxidative-inflammation conditions. In addition, these proteins share anti-apoptotic properties and are tumorigenic when expressed in cancer cells. This review summarizes the current knowledge about Hsp27 and alphaB-crystallin and the implications, either positive or deleterious, of these proteins in pathologies such as neurodegenerative diseases, myopathies, asthma, cataracts and cancers. Approaches towards therapeutic strategies aimed at modulating the expression and/or the activities of Hsp27 and alphaB-crystallin are presented.

Chaperone‐rich cell lysate embedded with BCR‐ABL peptide demonstrates enhanced anti‐tumor activity against a murine BCR‐ABL positive leukemia

Chaperone proteins are effective antitumor vaccines when purified from a tumor source, some of which are in clinical trials. Such vaccines culminate in tumor-specific T cell responses, implicating the role of adaptive immunity. We have developed a rapid and efficient procedure utilizing an isoelectric focusing technique to obtain vaccines from tumor or normal tissues called chaperone-rich cell lysate (CRCL). Tumor-associated peptides, the currency of T cell-mediated anticancer immunity, are believed to be purveyed by chaperone vaccines. Our purpose was to demonstrate our ability to manipulate the peptide antigen repertoire of CRCL vaccines as a novel anticancer strategy. Our methods allow us to prepare "designer" CRCL, utilizing the immunostimulation activity and the carrying capacity of CRCL to quantitatively acquire and deliver exogenous antigenic peptides (e.g., derived from the oncogenic BCR/ABL protein in chronic myelogenous leukemia). Using fluorescence-based and antigen-presentation assays, we determined that significant quantities of exogenously added peptide could accumulate in "designer" CRCL and could stimulate T cell activation. Further, we concluded that peptide-embedded CRCL, devoid of other antigens, could generate potent immunity against pre-established murine leukemia. Designer CRCL allows for the development of personalized vaccines against cancers expressing known antigens, by embedding antigens into CRCL derived from normal tissue.

Preparation of apoptotic tumor cells with replication-incompetent HSV augments the efficacy of dendritic cell vaccines

The use of dendritic cells (DCs) loaded with apoptotic tumor cells is an attractive approach to tumor vaccination in the absence of well-characterized tumor antigens. Apoptotic tumor cells are a convenient source of polyvalent tumor antigen, but may induce only weak immunization. We tested the role of replication-incompetent recombinant herpes simplex virus (HSV) d106 lacking all immediate early genes except ICP0 in the generation of apoptotic cells for tumor vaccination, using ID8-VEGF, a syngeneic mouse model of ovarian carcinoma expressing high levels of VEGF, and TC-1, a human papillomavirus (HPV) 16 E6- and E7-transformed adenocarcinoma. HSVd106 killed tumor cells by apoptosis. Tumor cells infected by HSVd106 were engulfed more avidly by immature DCs, and induced DC maturation more efficiently than tumor cells killed by ultraviolet B (UVB) radiation. HSVd106 infection induced stronger upregulation of heat shock protein (Hsp) 70 and glucose-related protein (GRP) 94 than UVB in cells undergoing apoptosis. Immunization of mice with DCs loaded with HSVd106-killed cells elicited stronger antitumor T-cell response, including tumor-reactive interferon-gamma-secreting and cytotoxic T cells, and resulted in significantly stronger delay in tumor growth than immunization with DCs loaded with UVB-killed tumor cells. Moreover, in the TC-1 model, a protective effect of vaccination (40% tumor free animals) was observed only after immunization with DCs loaded with HSVd106-killed cells. Thus, the use of replication-incompetent HSV strains lacking immediate early genes except ICP0 offers possible advantages in the preparation of whole tumor cell antigen for DC-based tumor vaccination.

NK cell-based immunotherapies against tumors

Natural killer (NK) cells provide the first line of defence against pathogens and tumors. Their activation status is regulated by pro-inflammatory cytokines and by ligands that either target inhibitory or activating cell surface receptors belonging to the immunoglobulin-like, C-type lectin or natural cytotoxicity receptor families. Apart from non-classical HLA-E, membrane-bound heat shock protein 70 (Hsp70) has been identified as a tumor-specific recognition structure for NK cells expressing high amounts of the C-type lectin receptor CD94, acting as one component of an activating heterodimeric receptor complex. Full-length Hsp70 protein (Hsp70) or the 14-mer Hsp70 peptide T-K-D-N-N-L-L-G-R-F-E-L-S-G (TKD) in combination with pro-inflammatory cytokines enhances the cytolytic activity of NK cells towards Hsp70 membrane-positive tumors. Based on these findings cytokine/TKD-activated NK cells were adoptively transferred in tumor patients. These findings were compared to results of clinical trials using cytokine-activated NK cells.

Intracellular and extracellular functions of heat shock proteins: repercussions in cancer therapy

Stress or heat shock proteins (HSPs) are the most conserved proteins present in both prokaryotes and eukaryotes. Their expression is induced in response to a wide variety of physiological and environmental insults. These proteins play an essential role as molecular chaperones by assisting the correct folding of nascent and stress-accumulated misfolded proteins, and preventing their aggregation. HSPs have a dual function depending on their intracellular or extracellular location. Intracellular HSPs have a protective function. They allow the cells to survive lethal conditions. Various mechanisms have been proposed to account for the cytoprotective functions of HSPs. Several HSPs have also been demonstrated to directly interact with various components of the tightly regulated programmed cell death machinery, upstream and downstream of the mitochondrial events. On the other hand, extracellular located or membrane-bound HSPs mediate immunological functions. They can elicit an immune response modulated either by the adaptive or innate immune system. This review will focus on HSP27, HSP70, and HSP90. We will discuss the dual role of these HSPs, protective vs. immunogenic properties, making a special emphasis in their utility as targets in cancer therapy.

HSP90 expression: a new predictive factor for BCG response in stage Ta-T1 grade 3 bladder tumours

OBJECTIVES

Although Bacillus Calmette-Guérin (BCG) instillations are considered as the adjuvant treatment of choice for stage Ta-T1 grade G3 bladder tumours, there is no consensus for a predictive factor to assess BCG success. This study attempted to evaluate if heat shock proteins (HSPs) could be useful predictive markers in BCG responses.

METHODS

Thirty-three primary resected G3 superficial bladder tumours were included in the study. All patients received adjuvant BCG instillations. The mean follow-up was 56 mo (range: 24-132 mo). HSP expression was evaluated by immunochemistry.

RESULTS

In the 33 patients, 18 had no recurrence (group 1), 9 had recurrence with no muscular invasion (group 2), and 6 had an invasive recurrence (group 3). A significant correlation was found between lack of expression of HSP90 and BCG response: the mean HSP expression was 92.7%, 84.4%, and 26.7% for groups 1, 2 and 3 tumours, respectively (p<0.0001). For the 6 patients who did not positively respond to BCG, HSP expression was <40%. All the tumours with a HSP90 expression >40% positively responded to BCG, corresponding to group 1 or 2 patients. In contrast, HSP60 expression was not correlated to the BCG response.

CONCLUSIONS

HSP90 could be considered as a very promising marker to assess BCG treatment response. Low HSP90 expression (<40%) could be useful to predict BCG failure and early stage cystectomy could be proposed for these selected patients with primary high-risk grade 3 superficial bladder tumours.

Cancer immunotherapy based on intracellular hyperthermia using magnetite nanoparticles: a novel concept of "heat-controlled necrosis" with heat shock protein expression

Heat shock proteins (HSPs) are highly conserved proteins whose syntheses are induced by a variety of stresses, including heat stress. Since the expression of HSPs, including HSP70, protects cells from heat-induced apoptosis, HSP expression has been considered to be a complicating factor in hyperthermia. On the other hand, recent reports have shown the importance of HSPs, such as HSP70, HSP90 and glucose-regulated protein 96 (gp96), in immune reactions. If HSP expression induced by hyperthermia is involved in tumor immunity, novel cancer immunotherapy based on this novel concept can be developed. In such a strategy, a tumor-specific hyperthermia system, which can heat the local tumor region to the intended temperature without damaging normal tissue, would be highly advantageous. To achieve tumor-specific hyperthermia, we have developed an intracellular hyperthermia system using magnetite nanoparticles. This novel hyperthermia system can induce necrotic cell death via HSP expression, which induces antitumor immunity. In the present article, cancer immunology and immunotherapy based on hyperthermia, and HSP expression are reviewed and discussed.

Effects of thermal stress on tumor antigenicity and recognition by immune effector cells

The primary rationale for the application of clinical hyperthermia in the therapy of cancer is based on the direct cytotoxic effect of heat and the radio-chemosensitization of tumor cells. More recently, additional attention is given to the observation that heat and heat-shock proteins can activate the host's immune system. The expression of heat-shock genes and proteins provides an adaptive mechanism for stress tolerance, allowing cells to survive non-physiologic conditions. However, the same adaptive mechanism can ultimately favor malignant transformation by interfering with pathways that regulate cell growth and apoptosis. Cytoprotection and thermotolerance raised the concern that heat-treated tumor cells might also be resistant to attack by immune effector mechanisms. Many studies, including those from our group, address this concern and document that heat-exposure, although transiently modulating sensitivity to CTL, do not hinder CTL attack. Moreover, there are promising reports of heat-related upregulation of NK-activating ligands, rendering those tumors which have lost MHC class I molecules target for NK cell attack. Heat-induced cytoprotection, therefore, does not necessarily extend protection from cytotoxic immune mechanisms. When interpreting the effects of heat, it is important to keep in mind that thermal effects on cell physiology are strongly dependent on the thermal dose, which is a function of the magnitude of change in temperature and the duration of heat exposure. The thermal dose required to induce cell death in vitro strongly varies from cell type to cell type and depends on microenvironmental factors (Dewey 1994). Therefore, to dissect the immunological behaviour of a given tumor and its micro-environment at different thermal doses, it is essential to characterize the thermosensitivity of every single tumor type and assess the proportion of cells surviving a given heat treatment. In this review, we summarize the pleiotropic effects that heat exposure has on tumor cells. In particular, we focus on the effects of heat on the antigen presentation of tumor cells and their susceptibility to immune effector mechanisms. We emphasize that the response to thermal stress is not a one-time point event, but rather a time period starting with the heat exposure and extending over several days of recovery. In addition, the response of tumor cells and their susceptibility to immune effector cells is strongly dependent on the model system, on the magnitude and duration of the thermal stress and on the time of recovery after heat exposure. Consideration of these aspects might help to explain some of the conflicting results that are reported in the field of thermal stress response.

Fusion proteins of Hsp70 with tumor-associated antigen acting as a potent tumor vaccine and the C-terminal peptide-binding domain of Hsp70 being essential in inducing antigen-independent anti-tumor response in vivo

Hsp70s are a family of ATP-dependent chaperones of relative molecular mass around 70 kDa. Immunization of mice with Hsp70 isolated from tumor tissues has been proved to elicit specific protective immunity against the original tumor challenge. In this work, we investigated whether Hsp70 can be used as vehicle to elicit immune response to its covalence-accompanying antigen. A recombinant protein expression vector was constructed that permitted the production of recombinant protein fusing tumor-associated antigen (eg, Mela) to the C terminus of Hsp70. We found that the Hsp70-Mela fusion protein can elicit strong cellular immune responses against murine tumor B16, which expresses protein Mela. The Hsp70 peptide-binding domain deletion mutant of the fusion protein was sufficient for inducing Mela-specific cytotoxic T lymphocyte but was not sufficient for engendering potent anti-tumor immunity against B16. We also found that host natural killer (NK) cells were stimulated in vivo by C-terminal domain of Hsp70. We thus presume that Hsp70 fusion proteins suppress tumor growth via at least 2 distinct pathways: one is covalence-accompanying antigen dependent; another is antigen independent. The C-terminal domain of Hsp70 seemed to be the crucial part in eliciting antigen-independent responses, including NK cell stimulation, against tumor challenges. Furthermore, we found that immunization with multiple Hsp70 fusion proteins resulted in a better anti-tumor effect.

Antibodies against heat shock proteins in environmental stresses and diseases: friend or foe?

Heat shock proteins (Hsps) can be found in two forms, intracellular and extracellular. The intracellular Hsps are induced as a result of stress and have been found to be cytoprotective in many instances due to their chaperone functions in protein folding and in protein degradation. The origin and role of extracellular Hsps is less clear. Although they were suspected originally to be released from damaged cells (necrosis), their presence in most normal individuals rather suggests that they have regulatory functions in circulation. As immunodominant molecules, Hsps can stimulate the immune system, leading to the production of autoantibodies recognizing epitopes shared by microbial and human Hsps. Thus, extracellular Hsps can influence the inflammatory response as evidenced by the production of inflammatory cytokines. Antibodies to Hsps have been found under normal conditions but seem to be increased in certain stresses and diseases. Such antibodies could regulate the inflammatory response positively or negatively. Here, we review the literature on the findings of antibodies to Hsps in situations of environmental or occupational stress and in a number of diseases and discuss their possible significance for the diagnosis, prognosis, or pathogenesis of these diseases.

Heat shock proteins in immunity

This chapter focuses on immunological effects of eukaryotic and microbial heat shock proteins (HSPs), with molecular weights of about 60, 70, and 90 kDa. The search for tumor-specific antigens resulted in the identification of HSPs. They have been found to elicit a potent anti-cancer immune response mediated by the adoptive and innate immune system. Following receptor-mediated uptake of HSP (HSP70 and gp96) peptide complexes by antigen-presenting cells and representation of HSP-chaperoned peptides by MHC class I molecules, a CD8-specific T cell response is induced. Apart from chaperoning immunogenic peptides derived from tumors, bacterial and virally infected cells, they by themselves provide activatory signals for antigen-presenting cells and natural killer (NK) cells. After binding of peptide-free HSP70 to Toll-like receptors, the secretion of pro-inflammatory cytokines is initiated by antigen-presenting cells and thus results in a nonspecific stimulation of the immune system. Moreover, soluble as well as cell membrane-bound HSP70 on tumor cells can directly activate the cytolytic and migratory capacity of NK cells. Apart form cancer, HSPs of different origins, with a molecular weight of about 60, 70, and 90 kDa, also play a pivotal role in viral infections, including human and simian immunodeficiency virus (HIV, SIV), measles, and choriomeningitis. Moreover, HSPs have been found to induce tolerance against autoimmune diseases. In summary, depending on their mode of induction, intracellular/extracellular location, cellular origin (eukaryote/prokaryote), peptide loading status, intracellular ADP/ATP content, concentration, and route of application, HSPs either exert immune activation as danger signals in cancer immunity and mediate protection against infectious diseases or exhibit regulatory activities in controlling and preventing autoimmunity.

Medical application of functionalized magnetic nanoparticles

Since magnetic particles have unique features, the development of a variety of medical applications has been possible. The most unique feature of magnetic particles is their reaction to a magnetic force, and this feature has been utilized in applications such as drug targeting and bioseparation including cell sorting. Recently, magnetic nanoparticles have attracted attention because of their potential as contrast agents for magnetic resonance imaging (MRI) and heating mediators for cancer therapy (hyperthermia). Magnetite cationic liposomes (MCLs), one of the groups of cationic magnetic particles, can be used as carriers to introduce magnetite nanoparticles into target cells since their positively charged surface interacts with the negatively charged cell surface; furthermore, they find applications to hyperthermic treatments. Magnetite nanoparticles conjugated with antibodies (antibody-conjugated magnetoliposomes, AMLs) are also applied to hyperthermia and have enabled tumor-specific contrast enhancement in MRI via systemic administration. Since magnetic nanoparticles are attracted to a high magnetic flux density, it is possible to manipulate cells labeled with magnetic nanoparticles using magnets; this feature has been applied in tissue engineering. Magnetic force and MCLs were used to construct multilayered cell structures and a heterotypic layered 3D coculture system. Thus, the applications of these functionalized magnetic nanoparticles with their unique features will further improve medical techniques.