Induction of cellular immunity by immunization with novel hybrid peptides complexed to heat shock protein 70

PA28γ, the ring that makes tumors invisible to the immune system?

PA28γ is a proteasomal interactor whose main and most known function is to stimulate the hydrolytic activity of the 20 S proteasome independently of ubiquitin and ATP. Unlike its two paralogues, PA28α and PA28β, PA28γ is largely present in the nuclear compartment and plays pivotal functions in important pathways such as cellular division, apoptosis, neoplastic transformation, chromatin structure and organization, fertility, lipid metabolism, and DNA repair mechanisms. Although it is known that a substantial fraction of PA28γ is found in the cell in a free form (i.e. not associated with 20 S), almost all of the studies so far have focused on its ability to modulate proteasomal enzymatic activities. In this respect, the ability of PA28γ to strongly stimulate degradation of proteins, especially if intrinsically disordered and therefore devoid of three-dimensional tightly folded structure, appears to be the main molecular mechanism underlying its multiple biological effects. Initial studies, conducted more than 20 years ago, came to the conclusion that among the many biological functions of PA28γ, the immunological ones were rather limited and circumscribed. In this review, we focus on recent evidence showing that PA28γ fulfills significant functions in cell-mediated acquired immunity, with a particular role in attenuating MHC class I antigen presentation, especially in relation to neoplastic transformation and autoimmune diseases.

Microbes mediated immunogenic cell death in cancer immunotherapy

Immunogenic cell death (ICD) is one of the 12 distinct cell death forms, which can trigger immune system to fight against cancer cells. During ICD, a number of cellular changes occur that can stimulate an immune response, including the release of molecules called damage-associated molecular patterns (DAMPs), signaling to immune cells to recognize and attack cancer cells. By virtue of their pivotal role in immune surveillance, ICD-based drug development has been a new approach to explore novel therapeutic combinations and personalized strategies in cancer therapy. Several small molecules and microbes can induce ICD-relevant signals and cause cancer cell death. In this review, we highlighted the role of microbe-mediate ICD in cancer immunotherapy and described the mechanisms through which microbes might serve as ICD inducers in cancer treatment. We also discussed current attempts to combine microbes with chemotherapy regimens or immune checkpoint inhibitors (ICIs) in the treatment of cancer patients. We surmise that manipulation of microbes may guide personalized therapeutic interventions to facilitate anticancer immune response.

Biomimetic nanoparticles for DC vaccination: a versatile approach to boost cancer immunotherapy

Cancer immunotherapy, which harnesses the immune system to fight cancer, has begun to make a breakthrough in clinical applications. Dendritic cells (DCs) are the bridge linking innate and adaptive immunity and the trigger of tumor immune response. Considering the cumbersome process and poor efficacy of classic DC vaccines, there has been interest in transferring the field of in vitro-generated DC vaccines to nanovaccines. Conventional nanoparticles have insufficient targeting ability and are easily cleared by the reticuloendothelial system. Biological components have evolved very specific functions, which are difficult to fully reproduce with synthetic materials, making people interested in using the further understanding of biological systems to prepare nanoparticles with new and enhanced functions. Biomimetic nanoparticles are semi-biological or nature-derived delivery systems comprising one or more natural materials, which have a long circulation time in vivo and excellent performance of targeting DCs, and can mimic the antigen-presenting behavior of DCs. In this review, we introduce the classification, design, preparation, and challenges of different biomimetic nanoparticles, and discuss their application in activating DCs in vivo and stimulating T cell antitumor immunity. Incorporating biomimetic nanoparticles into cancer immunotherapy has shown outstanding advantages in precisely coaxing the immune system against cancer.

Advances in the Development of Anticancer HSP-based Vaccines

Current advances in cancer treatment are based on the recent discoveries of molecular mechanisms of tumour maintenance. It was shown that heat shock proteins (HSPs) play a crucial role in the development of immune response against tumours. Thus, HSPs represent multifunctional agents not only with chaperone functions, but also possessing immunomodulatory properties. These properties are exploited for the development of HSP-based anticancer vaccines aimed to induce cytotoxic responses against tumours. To date, a number of strategies have been suggested to facilitate HSP-based vaccine production and to increase its effectiveness. The present review focuses on the current trend for the development of HSPbased vaccines aimed at inducing strong immunological tumour-specific responses against cancer cells of distinct etiology and localization.

Heat shock proteins 70 and 90 from Clonorchis sinensis induce Th1 response and stimulate antibody production

Background

Heat shock proteins (HSPs) are found in all prokaryotes and most compartments of eukaryotic cells. Members of the HSP family mediate immune responses to tissue damage or cellular stress. However, little is known about the immune response induced by the oriental liver fluke, Clonorchis sinensis, even though this organism is carcinogenic to humans. We address this issue in the present study in mouse bone marrow dendritic cells (mBMDCs), using recombinant HSP70 and 90 from C. sinensis (rCsHSP70 and rCsHSP90).

Methods

rCsHSP70 and rCsHSP90 were produced in an E. coli system. Purified recombinant proteins were treated in BMDCs isolated from C57BL/6 mice. T cells were isolated from Balb/c mice and co-cultured with activated mBMDCs. Expression of surface molecules was measured by flow cytometry and cytokine secretion was quantified using ELISA. C57BL/6 mice were divided into four groups, including peptide alone, peptide/Freund’s adjuvant, peptide/CsHSP70, peptide/CsHSP90, and were immunized intraperitoneally three times. Two weeks after final immunization, antibodies against peptide were measured using ELISA.

Results

Both proteins induced a dose-dependent upregulation in major histocompatibility complex and co-stimulatory molecule expression and increased secretion of pro-inflammatory cytokines including interleukin (IL)-1β, -6, and -12p70 and tumor necrosis factor-α in mBMDCs. Furthermore, when allogenic T cells were incubated with mBMDCs activated by rCsHSP70 and rCsHSP90, the helper T cell (Th)1 cytokine interferon-γ was up-regulated whereas the level of the Th2 cytokine IL-4 was unchanged. These results indicate that rCsHSPs predominantly induce a Th1 response. Over and above these results, we also demonstrated that the production of peptide-specific antibodies can be activated after immunization via in vitro peptide binding with rCsHSP70 or rCsHSP90.

Conclusion

This study showed for the first time that the HSP or HSP/peptide complexes of C. sinensis could be considered as a more effective vaccine against C. sinensis infection as results of the activator of host immune response as well as the adjuvant for antigenic peptide conjugate to induce peptide-specific antibody response in mice.

Unfolding the Role of Large Heat Shock Proteins: New Insights and Therapeutic Implications

Heat shock proteins (HSPs) of eukaryotes are evolutionarily conserved molecules present in all the major intracellular organelles. They mainly function as molecular chaperones and participate in maintenance of protein homeostasis in physiological state and under stressful conditions. Despite their relative abundance, the large HSPs, i.e., Hsp110 and glucose-regulated protein 170 (Grp170), have received less attention compared to other conventional HSPs. These proteins are distantly related to the Hsp70 and belong to Hsp70 superfamily. Increased sizes of Hsp110 and Grp170, due to the presence of a loop structure, result in their exceptional capability in binding to polypeptide substrates or non-protein ligands, such as pathogen-associated molecules. These interactions that occur in the extracellular environment during tissue injury or microbial infection may lead to amplification of an immune response engaging both innate and adaptive immune components. Here, we review the current advances in understanding these large HSPs as molecular chaperones in proteostasis control and immune modulation as well as their therapeutic implications in treatment of cancer and neurodegeneration. Given their unique immunoregulatory activities, we also discuss the emerging evidence of their potential involvement in inflammatory and immune-related diseases.

Activation of acid-sensing ion channels by localized proton transient reveals their role in proton signaling

Extracellular transients of pH alterations likely mediate signal transduction in the nervous system. Neuronal acid-sensing ion channels (ASICs) act as sensors for extracellular protons, but the mechanism underlying ASIC activation remains largely unknown. Here, we show that, following activation of a light-activated proton pump, Archaerhodopsin-3 (Arch), proton transients induced ASIC currents in both neurons and HEK293T cells co-expressing ASIC1a channels. Using chimera proteins that bridge Arch and ASIC1a by a glycine/serine linker, we found that successful coupling occurred within 15 nm distance. Furthermore, two-cell sniffer patch recording revealed that regulated release of protons through either Arch or voltage-gated proton channel Hv1 activated neighbouring cells expressing ASIC1a channels. Finally, computational modelling predicted the peak proton concentration at the intercellular interface to be at pH 6.7, which is acidic enough to activate ASICs in vivo. Our results highlight the pathophysiological role of proton signalling in the nervous system.

In Vivo Suppression of Heat Shock Protein (HSP)27 and HSP70 Accelerates DMBA-Induced Skin Carcinogenesis by Inducing Antigenic Unresponsiveness to the Initiating Carcinogenic Chemical

Heat shock proteins (HSPs) are constitutively expressed in murine skin. HSP27 is present in the epidermis, and HSP70 can be found in both the epidermis and dermis. The purpose of this study was to investigate the role of these proteins in cutaneous chemical carcinogenesis and to determine whether their effects on cell-mediated immune function were a contributing factor. In vivo inhibition of HSP27 and HSP70 produced a reduction in the T cell-mediated immune response to 7,12-dimethylbenz(a)anthracene (DMBA) and benzo(a)pyrene in C3H/HeN mice and resulted in a state of Ag-specific tolerance. When mice were pretreated with anti-HSP27 and anti-HSP70 Abs in vivo prior to subjecting them to a standard two-stage DMBA/12-O-tetradecanoylphorbol-13-acetate cutaneous carcinogenesis protocol, the percentage of mice with tumors was much greater (p < 0.05) in anti-HSP27- and HSP70-pretreated animals compared with mice pretreated with control Ab. Similar results were obtained when the data were evaluated as the cumulative number of tumors per group. Mice pretreated with HSP27 and HSP70 Abs developed more H-ras mutations and fewer DMBA-specific cytotoxic T lymphocytes. These findings indicate that in mice HSP27 and HSP70 play a key role in the induction of cell-mediated immunity to carcinogenic polyaromatic hydrocarbons. Bolstering the immune response to carcinogenic polyaromatic hydrocarbons may be an effective method for prevention of the tumors that they produce.

Exogenously delivered heat shock protein 70 displaces its endogenous analogue and sensitizes cancer cells to lymphocytes-mediated cytotoxicity

Hsp70 chaperone is known to stimulate anti-tumour immunity in a variety of cancer models. Here we demonstrated that the addition of purified recombinant Hsp70 to the culture medium facilitated cancer cell cytolysis by lymphocytes. Importantly, exogenous Hsp70 triggered secretion of the intracellular Hsp70 to a cell surface and extracellular milieu, which played a role in cytolysis because down-regulation of the endogenous Hsp70 reduced both its presence at the cell surface and the lymphocyte-mediated cytolysis. Inhibitors that target both the ATPase and the peptide-binding domains of Hsp70 molecule potently decreased its anti-tumor effect. Using a variety of cell transport markers and inhibitors, we showed that the exchange of exogenous and intracellular Hsp70 is supported by classical and non-classical transport pathways, with a particular role of lipid rafts in the chaperone's intracellular transport. In conclusion, exogenous Hsp70 can eject endogenous Hsp70, thus exerting anticancer activity.

Effects of L-proline on the Growth Performance, and Blood Parameters in Weaned Lipopolysaccharide (LPS)-challenged Pigs

This trail was conducted to study the effect of L-proline on the growth performance, and blood parameter in the weaned lipopolysaccharide (LPS)-challenged pigs. Thirty six pigs (9.13±0.85 kg) were assigned randomly to dietary treatments in a 2×3 factorial arrangement in a 20-d growth assay. Factors were intraperitoneal injection with saline or LPS, and three dietary L-proline supplement levels (0%, 0.5%, or 1.0%). On d 10, blood samples were collected at 3 h after LPS (100 μg LPS/kg body weight [BW]) or saline injection. On d 20 of the trial, all pigs were orally administrated D-xylose (0.1 g/kg BW) at 2 h, and blood samples were collected at 3 h after LPS or saline injection. As a result, dietary supplementation with 0.5% proline had a tendency to increase average daily gain (ADG) in piglets during d 10 to 20 (p = 0.088). Without LPS challenge, dietary supplementation with 1.0% proline had no effect on growth hormone (GH) concentrations on d 10 (p>0.05), but decreased it after LPS challenge (p<0.05). There was LPS challenge×proline interaction for GH concentrations on d 10 (p<0.05). Dietary supplementation with 1.0% proline decreased glucagon concentration on d 10 after LPS challenge (p<0.05). In addition, dietary supplementation with proline increased superoxide dismutase (SOD) activity significantly on d 10 and 20 (p<0.05), and 1.0% proline increased heat shock proteins-70 concentration on d 10 (p<0.05). Moreover, proline supplementation increased diamine oxidase (DAO) concentrations after LPS challenge (p<0.05). There was LPS challenge×proline interaction for DAO (p<0.05). Furthermore, dietary supplementation with 1.0% proline increased the D-xylose level when no LPS challenge (p<0.05). These results indicate that proline supplementation could improve growth performance, increase SOD activities, and has a positive effect on the gastrointestinal tract digestibility in early weaned pigs.

Stimulating antitumor immunity with nanoparticles

A variety of strategies, have been applied to cancer treatment and the most recent one to become prominent is immunotherapy. This interest has been fostered by the demonstration that the immune system does recognize and often eliminate small tumors but tumors that become clinical problems block antitumor immune responses with immunosuppression orchestrated by the tumor cells. Methods to reverse this tumor-mediated immunosuppression will improve cancer immunotherapy outcomes. The immunostimulatory potential of nanoparticles (NPs), holds promise for cancer treatment. Phagocytes of various types are an important component of both immunosuppression and immunostimulation and phagocytes actively take up NPs of various sorts, so NPs are a natural system to manipulate these key immune regulatory cells. NPs can be engineered with multiple useful therapeutic features, such as various payloads such as antigens and/or immunomodulatory agents including cytokines, ligands for immunostimulatory receptors or antagonists for immunosuppressive receptors. As more is learned about how tumors suppress antitumor immune responses the payload options expand further. Here we review multiple approaches of NP-based cancer therapies to modify the tumor microenvironment and stimulate innate and adaptive immune systems to obtain effective antitumor immune responses.

The double-edged sword: conserved functions of extracellular hsp90 in wound healing and cancer

Heat shock proteins (Hsps) represent a diverse group of chaperones that play a vital role in the protection of cells against numerous environmental stresses. Although our understanding of chaperone biology has deepened over the last decade, the “atypical” extracellular functions of Hsps have remained somewhat enigmatic and comparatively understudied. The heat shock protein 90 (Hsp90) chaperone is a prototypic model for an Hsp family member exhibiting a duality of intracellular and extracellular functions. Intracellular Hsp90 is best known as a master regulator of protein folding. Cancers are particularly adept at exploiting this function of Hsp90, providing the impetus for the robust clinical development of small molecule Hsp90 inhibitors. However, in addition to its maintenance of protein homeostasis, Hsp90 has also been identified as an extracellular protein. Although early reports ascribed immunoregulatory functions to extracellular Hsp90 (eHsp90), recent studies have illuminated expanded functions for eHsp90 in wound healing and cancer. While the intended physiological role of eHsp90 remains enigmatic, its evolutionarily conserved functions in wound healing are easily co-opted during malignancy, a pathology sharing many properties of wounded tissue. This review will highlight the emerging functions of eHsp90 and shed light on its seemingly dichotomous roles as a benevolent facilitator of wound healing and as a sinister effector of tumor progression.

Heat shock protein profiles on the protein and gene expression levels in olive flounder kidney infected with Streptococcus parauberis

Heat shock proteins (HSPs) have been observed in cells exposed to a variety of stresses, including infectious pathogens. This study used a label-free, quantitative proteomic approach and transcriptional gene expression analysis to investigate infection-related HSP proteins and their encoding genes in whole kidneys from olive flounder (Paralichthys olivaceus). During Streptococcus parauberis infection in the flounder, the genes encoding Hsp10, Hsp40A4, Hsp40B6, Hsp40B11, Hsp60, Hsp70, glucose regulated protein 78 (Grp78), Hsp90α, Hsp90β and Grp94 were induced, and the protein levels of Hsp60, Hsp70, Hsp90α, Hsp90β and Grp94 were differentially regulated over time. Subsequent results also revealed that Hsp60, Hsp70, Hsp90α, Hsp90β and Grp94 appear to be the dominant and critical HSPs in olive flounder during bacterial infection. This is the first estimation of the differential involvement of HSPs in the immune response of olive flounder exposed to bacterial infection.

The 'peptidome' of tumour-derived chaperone-rich cell lysate anti-cancer vaccines reveals potential tumour antigens that stimulate tumour immunity

Tumour-derived chaperone-rich cell lysate (CRCL) when isolated from tumour tissue or when embedded with peptide antigens is a potent anti-cancer vaccine consisting of numerous chaperone/heat shock proteins, including the highly immunogenic Hsp70, Hsp90, glucose regulated protein 94, and calreticulin. We have previously documented that CRCL provides both a source of tumour antigens and danger signals triggering antigen presenting cell activation. In this report we describe the 'peptidome' of potential antigens extracted from CRCL prepared from a murine tumour. Using mass spectrometry techniques we identify almost 60 different proteins of origin for the CRCL peptides; we determine that the parental proteins come from essentially all parts of the cell, and are involved in a broad range of functions. Further in silico analysis demonstrates that the parental proteins are components of major signalling networks of vital importance for cancer cell survival, proliferation, and migration. In many instances the peptides identified possess amino acid sequences that would allow their putative binding and display by murine major histocompatibility complex class I and II molecules, and there are also predicted binding motifs for Hsp70-type chaperones. By mixing fractionated pools of peptides with antigen-free (normal liver) CRCL, we were able to reconstitute effective anti-tumour activity of the vaccine, showing that the peptides are indeed the major purveyors of CRCL vaccines' efficacy.

[Analysis of complex formation of human recombinant HSP70 with tumor-associated peptides]

Molecular chaperones of HSP70 family assists presentation of exogenous antigenic peptides by antigen-presenting cells (APC). HSP70-peptide complexes are powerful immunotherapeutic agents, which enhance cross-presentation of captured antigen in dendritic cells and macrophages. Several clinical trials have shown that HSP-based cancer vaccines possess good efficacy and safety. However, sometime it is impossible to isolate sufficient amount of vaccine. These make us to pay attention for recombinant HSP70-based vaccines and to optimize in vitro complex formation mechanism. Here we have investigated two human recombinant proteins HSP70(HYB) and HSC70. Optimal values of ADP concentration, pH, temperature and peptides excess are determined in this work. We have also shown that proposed complex formation method enriches eluted from HSP70-complexes peptide repertoire compared to in vivo assembled ones.

An anti-nucleic acid antibody delivers antigen to the cross-presentation pathway in dendritic cells and potentiates therapeutic antitumor effects

Cross-presentation is important for initiating CTL responses against tumors. Delivery of exogenous Ags to the cross-presentation pathway in dendritic cells (DCs), using a number of different carriers, has been attempted to further understand the mechanisms underlying cross-presentation and to develop therapeutic tumor vaccines. The present study reports a new antigenic carrier molecule: a single-chain V region fragment (scFv) of a nucleic acid-hydrolyzing Ab, 3D8. A fusion protein comprising 3D8 scFv and the CTL epitope OVA(250-264) (chicken OVA aa 250-264) was internalized by DC2.4 DCs and processed via a proteasome-dependent, brefeldin- and cycloheximide-sensitive, chloroquine- and primaquine-insensitive pathway, resulting in loading of the CTL epitope onto H-2K(b). In vivo cross-presentation and cross-priming were efficient, even without adjuvant; injection of mice with 3D8 scFv-OVA(250-264) induced cross-presentation of the CTL epitope by draining lymph node CD11c(+) B7.1(+) MHC class II(high) DCs, elicited a CTL response, and suppressed the growth of tumors expressing the OVA epitope. This report shows that an anti-nucleic acid Ab is used to deliver exogenous Ag to the cross-presentation pathway and inhibit in vivo tumor growth.

Heat shock protein 70: roles in multiple sclerosis

Heat shock proteins (HSP) have long been considered intracellular chaperones that possess housekeeping and cytoprotective functions. Consequently, HSP overexpression was proposed as a potential therapy for neurodegenerative diseases characterized by the accumulation or aggregation of abnormal proteins. Recently, the discovery that cells release HSP with the capacity to trigger proinflammatory as well as immunoregulatory responses has focused attention on investigating the role of HSP in chronic inflammatory autoimmune diseases such as multiple sclerosis (MS). To date, the most relevant HSP is the inducible Hsp70, which exhibits both cytoprotectant and immunoregulatory functions. Several studies have presented contradictory evidence concerning the involvement of Hsp70 in MS or experimental autoimmune encephalomyelitis (EAE), the MS animal model. In this review, we dissect the functions of Hsp70 and discuss the controversial data concerning the role of Hsp70 in MS and EAE.

Membrane-bound HSP70-engineered myeloma cell-derived exosomes stimulate more efficient CD8(+) CTL- and NK-mediated antitumour immunity than exosomes released from heat-shocked tumour cells expressing cytoplasmic HSP70

Exosomes (EXO) derived from tumour cells have been used to stimulate antitumour immune responses, but only resulting in prophylatic immunity. Tumour-derived heat shock protein 70 (HSP70) molecules are molecular chaperones with a broad repertoire of tumour antigen peptides capable of stimulating dendritic cell (DC) maturation and T-cell immune responses. To enhance EXO-based antitumour immunity, we generated an engineered myeloma cell line J558_HSP expressing endogenous P1A tumour antigen and transgenic form of membrane-bound HSP70 and heat-shocked J558_HS expressing cytoplasmic HSP70, and purified EXO_HSP and EXO_HS from J558_HSP and J558_HS tumour cell culture supernatants by ultracentrifugation. We found that EXO_HSP were able to more efficiently stimulate maturation of DCs with up-regulation of Ia^b, CD40, CD80 and inflammatory cytokines than EXO_HS after overnight incubation of immature bone-marrow-derived DCs (5 × 10⁶ cells) with EXO (100 μg), respectively. We also i.v. immunized BALB/c mice with EXO (30 μg/mouse) and assessed P1A-specific T-cell responses after immunization. We demonstrate that EXO_HSP are able to stimulate type 1 CD4⁺ helper T (Th1) cell responses, and more efficient P1A-specific CD8⁺ cytotoxic T lymphocyte (CTL) responses and antitumour immunity than EXO_HS. In addition, we further elucidate that EXO_HSP-stimulated antitumour immunity is mediated by both P1A-specific CD8⁺ CTL and non-P1A-specific natural killer (NK) responses. Therefore, membrane-bound HSP70-expressing tumour cell-released EXO may represent a more effective EXO-based vaccine in induction of antitumour immunity.

Extracellular heat shock protein 90 plays a role in translocating chaperoned antigen from endosome to proteasome for generating antigenic peptide to be cross-presented by dendritic cells

Extracellular heat shock protein can deliver associated antigens into the MHC class I presentation pathway of antigen-presenting cells, a process called cross-presentation, thus inducing antigen-specific CD8(+) T-cell responses; however, the precise mechanism for intracellular antigen translocation and the processing pathway has not been fully elucidated. Here we demonstrate that cross-presentation of extracellular Hsp90-ovalbumin (OVA) protein complexes to specific CD8(+) T cells involves both classical proteasome-transporter-associated antigen processing (TAP)-dependent and TAP-independent-endosomal pathways. Using confocal microscopy, we found that the internalized extracellular Hsp90 and OVA co-localized with cytosolic proteasomes. When anti-Hsp90 mAb was introduced to dendritic cells (DCs), we observed that the co-localization of internalized Hsp90-chaperoned OVA and proteasomes was abolished, resulting in the inhibition of TAP-dependent cross-presentation of OVA. Thus, extracellular Hsp90 may play a pivotal role for the translocation of chaperoned antigens for proteasomal degradation in the cytosol. In contrast, OVA chaperoned by Hsp90 was not presented by MHC class II molecules in vitro or in vivo, although the antigen was exogenously loaded onto DCs. Our data indicate that extracellular Hsp90 might be essential for the translocation of chaperoned antigens from the extracellular milieu into cytosol, resulting in proteasomal degradation for cross-presentation.

Heat shock protein 70 (Hsp70)-stimulated deoxycytidine deaminases from a human lymphoma cell but not the activation-induced cytidine deaminase (AID) from Ramos 6.4 human Burkitt's lymphoma cells

Deoxycytidine deaminase enzyme activity was reduced in lysates of human leukemic THP1 cells 24 h after transfection with siRNA designed to inhibit cell synthesis of heat shock protein 70 (Hsp70)1a and Hsp701b. The cytidine deaminase enzyme activity from the cell lysates was purified from an affinity column which contained bound single-stranded oligodeoxycytidylic acid. Deficient enzyme activity in certain elution fractions from the siRNA-transfected cells was restored by including recombinant HSP 70 in the assays. Enzyme activity in some other fractions was increased after siRNA transfection. Activation-induced cytidine deaminase (AID) is a central factor in the immune response. A more specific assay for AID was used to study the influence of Hsp70 on AID activity. Unlike Hsp70's ability to stimulate certain enzymes of DNA base excision repair and other cytidine deaminases, it had little effect on AID activity in vitro, or was weakly inhibitory.

Superior antitumor response induced by large stress protein chaperoned protein antigen compared with peptide antigen

Our previous studies have demonstrated that the natural chaperone complexes of full-length tumor protein Ags (e.g., gp100) and large stress proteins (e.g., hsp110 and grp170) with exceptional Ag-holding capabilities augment potent tumor protective immunity. In this study, we assess the peptide-interacting property of these large chaperones and, for the first time, compare the immunogenicity of the recombinant chaperone vaccines targeting two forms of Ags (protein versus peptide). Both hsp110 and grp170 readily formed complexes with antigenic peptides under physiologic conditions, and the peptide association could be further stimulated by heat shock. The large chaperones displayed similar but distinct peptide-binding features compared with hsp70 and grp94/gp96. Immunization with hsp110- or grp170-tyrosinase-related protein 2 (TRP2(175-192)) peptide complexes effectively primed CD8(+) T cells reactive with TRP2-derived, MHC class I-restricted epitope. However, the tumor protective effect elicited by the TRP2(175-192) peptide vaccine was much weaker than that achieved by full-length TRP2 protein Ag chaperoned by grp170. Furthermore, immunization with combined chaperone vaccines directed against two melanoma protein Ags (i.e., gp100 and TRP2) significantly improved overall anti-tumor efficacy when compared with either of the single Ag vaccine. Lastly, treatment of tumor-bearing mice with these dual Ag-targeted chaperone complexes resulted in an immune activation involving epitope spreading, which was associated with a strong growth inhibition of the established tumors. Our results suggest that high m.w. chaperones are superior to conventional chaperones as a vaccine platform to deliver large protein Ags, and provide a rationale for translating this recombinant chaperoning-based vaccine to future clinical investigation.

Enhanced antigen uptake by dendritic cells induced by the B pentamer of the type II heat-labile enterotoxin LT-IIa requires engagement of TLR2

The potent mucosal adjuvant properties of the type II heat-labile enterotoxin LT-IIa of Escherichia coli are dependent upon binding of the B pentamer of the enterotoxin (LT-IIa-B(5)) to ganglioside receptors on immunocompetent cells. To evaluate the immunomodulatory activities of LT-IIa-B(5), in vitro experiments employing bone marrow-derived dendritic cells (BMDC) were performed. Uptake of OVA-FITC, a model antigen (Ag), was enhanced by treatment of BMDC with LT-IIa-B5, but not by treatment of cells with the B pentamer of cholera toxin (CTB). Expression of co-stimulatory molecules (CD40, CD80, CD86, and MHC-II) and cytokines (IL-12p40, TNF-alpha, and IFN-gamma) was increased in BMDC treated with LT-IIa-B(5). The capacity of LT-IIa-B(5) to enhance Ag uptake and to induce expression of co-stimulatory receptors and cytokines by BMDC was dependent upon expression of TLR2 by the cell. Increased Ag uptake induced by LT-IIa-B(5) was correlated with increased Ag-specific proliferation of CD4(+) T cells in an in vitro syngeneic DO11.10 CD4(+) T cell proliferation assay. These experiments confirm that LT-IIa-B(5) exhibits potent immunomodulatory properties which may be exploitable as a non-toxic mucosal adjuvant.

Induction of tumor-specific immune response by gene transfer of Hsp70-cell-penetrating peptide fusion protein to tumors in mice

To induce a tumor-specific immune response by delivering tumor-associated antigens in tumor cells to antigen-presenting cells (APCs), we designed a fusion protein which consists of heat-shock protein 70 (Hsp70) and the C-terminal 34 amino acids of herpes simplex virus VP22 protein (VP22(268-301)), the former having a peptide binding domain and an ability to be recognized by APCs, and the latter able to achieve cell penetration. Hsp70-VP22(268-301), the fusion protein, was efficiently taken up by mouse dendritic cell (DC) line DC2.4. Major histocompatibility complex (MHC) class I-restricted presentation of an epitope peptide of ovalbumin (OVA) was examined in DC2.4, and Hsp70-VP22(268-301) significantly increased the presentation of the peptide compared with Hsp70. Electroporation-assisted injection of naked plasmid vector expressing Hsp70-VP22(268-301) (pHsp70-VP22(268-301)) into subcutaneous tumors of EG7-OVA, a mouse lymphoma-expressing OVA, significantly increased the survival of mice compared with the same treatment with pHSp70, a plasmid expressing Hsp70. Splenocytes from the pHsp70-VP22(268-301)-treated mice exhibited cytolytic activity against both EG7-OVA and the parent EL4, but not against mouse melanoma B16-F10, suggesting that not only OVA-derived antigens but those common to EG7-OVA and EL4 are delivered to APCs. These results provide a new therapeutic method to induce tumor-specific antitumor immunity without identifying nor isolating tumor-associated antigens.

Current ideas about applications of heat shock proteins in vaccine design and immunotherapy

Heat shock proteins (HSPs), as molecular chaperones, perform critical functions in maintaining cell homeostasis. Certain HSPs in extra-cellular milieu are capable of modulating innate and adaptive immunity due to their ability to chaperone polypeptides and to interact with the host's immune system, particularly professional antigen presenting cells (APCs). This review summarizes the immunomodulating functions of HSPs and their potential applications in cancer immunotherapy.

Molecular or pharmacologic inhibition of the CD14 signaling pathway protects against burn-related myocardial inflammation and dysfunction

Signaling through toll-like receptor 4 (TLR4) plays an obligate role in burn-related myocardial dysfunction. We hypothesized that signaling through CD14, a cellular receptor for endotoxin that lacks a transmembrane domain but is coupled to TLR4, also plays a role in postburn myocardial inflammation and dysfunction. Burn covering 40% total body surface area (or sham burn for controls) was produced in wild-type (WT) and CD14 knockout (KO) as well as vehicle-treated and geldanamycin-treated WT mice (1 microg/g body weight) to inhibit CD14 signaling. Groups included (1) WT shams, (2) CD14 KO sham, (3) WT burns, (4) CD14 KO burns, (5) vehicle-treated WT shams, (6) geldanamycin-treated WT shams, (7) vehicle-treated WT burns, and (8) geldanamycin-treated WT burns. Twenty-four hours after burn, cardiac function (Langendorff) and cardiomyocyte secretion of inflammatory cytokines TNF-alpha, IL-1 beta, and IL-6 (in pg/mL; 5 x 10(4) myocytes) were studied in all groups. Relative to sham WT controls, burn trauma in increased cardiac myocyte secretion of inflammatory cytokines (TNF-alpha, IL-1 beta, and IL-6 rose from 59 +/- 10 to 171 +/- 8; 6 +/- 0.2 to 78 +/- 1; and 88 +/- 3 to 170 +/- 12 pg/mL, respectively; P < 0.05) and produced robust cardiac contractile dysfunction (left ventricular pressure and +dP/dt fell from 105 +/- 4 to 73 +/- 5 mmHg and 2,400 +/- 73 to 1,803 +/- 90 mmHg/s; P < 0.05). Inability to signal through the CD14/TLR4 pathway (induced by CD14/KO or inhibition of CD14 expression by administration of geldanamycin) attenuated TNF-alpha, IL-1 beta, and IL-6 production in response to burn injury and improved postburn myocardial contractile function. Our data suggest that signaling through the CD14 pathway plays an obligate role in cardiac inflammation/dysfunction which occurs after major burn injury.

Mitochondrial heat shock protein (HSP) 70 synergizes with HSP60 in transducing endothelial cell apoptosis induced by anti-HSP60 autoantibody

Heat shock protein (HSP) 60, up-regulated by endothelial cells (ECs) to resist stress, is the target of a subgroup of apoptosis-inducing anti-EC autoantibodies (Abs) in human vasculitides. Given that HSP60 is not a transmembrane protein, the mechanism by which these auto-Abs induces apoptosis is unclear. EC membrane proteins were analyzed using bidimensional electrophoresis and Far Western blot, and the HSP60 receptor was identified by mass spectrometry. Heat stress-dependent synthesis of HSP60 and receptor was examined by semiquantitative RT-PCR, and expression was examined by flow cytometry and indirect immunofluorescence. Interaction was demonstrated by coimmunoprecipitations. Lipid rafts were purified to evaluate specific localization, and the apoptotic response was investigated by blocking monoclonal Ab. Mitochondrial HSP70 (mtHSP70) was identified as an HSP60 receptor. Stress was required for ECs to up-regulate mRNA and express mtHSP70 on their surface. HSP60 and mtHSP70 colocalized and interacted within lipid rafts. They were associated with chemokine CC motif receptor 5 (CCR5), also induced at the mRNA and protein levels in stressed ECs. CCR5 was involved in the anti-HSP60-triggered apoptosis of ECs. These results provide new insights into the mechanism by which anti-EC auto-Abs from vasculitides induce apoptosis of ECs.

Interaction of human heat shock protein 70 with tumor-associated peptides

Molecular chaperones of the heat shock protein 70 (Hsp70) family play a crucial role in the presentation of exogenous antigenic peptides by antigen-presenting cells (APCs). In a combined biochemical and immunological approach, we characterize the biochemical interaction of tumor-associated peptides with human Hsp70 and show that the strength of this interaction determines the efficacy of immunological cross-presentation of the antigenic sequences by APCs. A fluorescein-labeled cytosolic mammalian Hsc70 binding peptide is shown to interact with human Hsp70 molecules with high affinity (Kd=0.58 μm at 25°C). Competition experiments demonstrate weaker binding by Hsp70 of antigenic peptides derived from the tumor-associated proteins tyrosinase (Kd=32 μm) and melanoma antigen recognized by T cells (MART-1) (Kd=2.4 μm). Adding a peptide sequence (pep70) with high Hsp70 binding affinity (Kd=0.04 μm) to the tumor-associated peptides enables them to strongly interact with Hsp70. Presentation of tumor-associated peptides by B cells resulting in T cell activation in vitro is enhanced by Hsp70 when the tumor-associated peptides contain the Hsp70 binding sequence. This observation has relevance for vaccine design, as augmented transfer of tumor-associated antigens to APCs is closely linked to the vaccine's efficacy of T cell stimulation.

Secretion of stress protein grp170 promotes immune-mediated inhibition of murine prostate tumor

It is well established that certain stress proteins or molecular chaperones are highly efficient in cross-presenting tumor-derived antigens, resulting in a potent antitumor immune response. In this study we demonstrate that genetic modification of weakly immunogenic murine prostate tumor cells (TRAMP-C2) by stable transfection with a secretable form of endoplasmic reticulum resident chaperone grp170 significantly enhances its immunogenicity in vivo. Generation of systemic antitumor immunity is indicated by the growth suppression of distant parental tumors, which is associated with increased tumor infiltration, elevated effector functions of CD8(+) T-cells. Immunization with inactivated grp170-secreting C2 cells augments a CD8(+) T-cell dependent, tumor-protective effect. Furthermore, infection of C2 tumor cells with a nonreplicating adenoviral vectors encoding secretable grp170 promotes tumor immunogenicity more effectively than plasmid transduction, as shown by the increased production of pro-inflammatory cytokine TNF-alpha by dendritice cells and enhanced therapeutic efficacy in treating pre-established tumors. Given a repertoire of undefined antigens in prostate tumor, manipulation of cellular compartmentalization of immuno-stimulatory chaperone grp170 to elicit systemic tumor immunity may be used to improve treatment outcomes for prostate cancer when combined with other treatment modalities.

Recombinant complexes of antigen with stress proteins are potent CD8 T-cell-stimulating immunogens

Heat shock proteins (Hsp) of the Hsp70/90 families facilitate cellular immune responses to antigenic peptides or proteins bound to them and have therefore been used as vaccine vehicles. We developed an expression system in which chimeric proteins with an Hsp-capturing, viral J domain fused to diverse antigen-encoding sequences form stable complexes with eukaryotic (Hsp70, Hsp73) or bacterial (DnaK) stress proteins and accumulate to high steady-state levels. J domains from different species (viruses/SV40, bacteria/Chlamydia trachomatis or plants/Arabidopsis thaliana) efficiently capture murine or human stress proteins in this system, thus making different J domains available for vaccine production. A novel expression and purification method was developed to produce native Hsp/antigen complexes in transfectants. These purified Hsp/antigen complexes efficiently elicited antigen-specific CD8 T cell responses in mice when delivered as vaccines without adjuvants. In situ complex formation of antigen with Hsp was critical for CD8 T cell priming. Because the described expression system supports the flexible design of multivalent vaccines, it is an attractive strategy to elicit CD8 T cell responses either to recombinant proteins or to selected antigenic domains of these molecules.

Human recombinant heat shock protein 70 affects the maturation pathways of dendritic cells in vitro and has an in vivo adjuvant activity

Heat shock proteins (HSPs) are potent inducers of an antigen-specific immunological response. A role of chaperon of immunogenic peptides and a direct effect on APC activation and function have been described. However, the signal transduction events involved in the activation of human APCs are poorly characterized. We investigated, using human monocyte-derived dendritic cells (DCs), the signal transduction pathways activated by a human recombinant HSP70 (r)HSP70 purified from eukaryotic cells. rHSP70 effectively induced a partial maturation of DCs in vitro and a significant increase in the titers of antigen-specific IgG when used as a vaccine adjuvant in vivo. rHSP70 did not desensitize human DCs to LPS stimulation and retained its adjuvant properties in C3H/HeJ mice, which are LPS-resistant as a result of a mutation in TLR-4, ruling out the potential interference of LPS contamination. Effects on DC maturation and in vivo functions correlate to the ability of rHSP70 to activate IkappaB-alpha/NF-kappaB and ERK1/2 pathways in human DCs. No activation of p38 was induced in the same experimental conditions. Our data suggest that the IkappaB-alpha/NF-kappaB pathway has a critical role in the partial maturation of DCs induced by rHSP70.

Human heat shock protein 70 enhances tumor antigen presentation through complex formation and intracellular antigen delivery without innate immune signaling

Heat shock proteins (HSPs) have shown promise for the optimization of protein-based vaccines because they can transfer exogenous antigens to dendritic cells and at the same time induce their maturation. Great care must be exercised in interpretating HSP-driven studies, as by-products linked to the recombinant generation of these proteins have been shown to mediate immunological effects. We generated highly purified human recombinant Hsp70 and demonstrated that it strongly enhances the cross-presentation of exogenous antigens resulting in better antigen-specific T cell stimulation. Augmentation of T cell stimulation was a direct function of the degree of complex formation between Hsp70 and peptides and correlated with improved antigen delivery to endosomal compartments. The Hsp70 activity was independent of TAP proteins and was not inhibited by exotoxin A or endosomal acidification. Consequently, Hsp70 enhanced cross-presentation of various antigenic sequences, even when they required different post-uptake processing and trafficking, as exemplified by the tumor antigens tyrosinase and Melan-A/MART-1. Furthermore, Hsp70 enhanced cross-presentation by different antigen-presenting cells (APCs), including dendritic cells and B cells. Importantly, enhanced cross-presentation and antigen-specific T cell activation were observed in the absence of innate signals transmitted by Hsp70. As Hsp70 supports the cross-presentation of different antigens and APCs and is inert to APC function, it may show efficacy in various settings of immune modulation, including induction of antigen-specific immunity or tolerance.

Evaluation of renal cell carcinoma vaccines targeting carbonic anhydrase IX using heat shock protein 110

Carbonic anhydrase IX (CA9) is a renal cell carcinoma (RCC)-specific tumor protein that is targeted using heat shock protein 110 (hsp110). The chaperoning ability of hsp110 can be utilized to form a complex with CA9 (hsp110 + CA9) in vitro, which can be administered as a highly concentrated tumor vaccine. In a tumor prevention model, hsp110 + CA9 prevented the growth of RENCA tumors in BALB/c mice, and produced IFN-gamma response measured using ELISPOT and an antibody response measured using ELISA. To test a second vaccine strategy, hsp110 complexed to a previously described CA9 peptide prevented tumor growth and produced a very weak IFN-gamma response, but no antibody response. A plasmid vector containing grp170, a member of the hsp110 family, linked to CA9 did not produce an antitumor response and produced no IFN-gamma response or antibodies. In a model of metastatic RCC, RENCA cells were injected intradermally prior to vaccination. Hsp110 + CA9 decreased tumor growth compared to control vaccinations. These studies suggest that recombinant hsp110 complexed to CA9 should be evaluated for treatment of RCC.

[Development of heat shock proteins with controlled distribution properties and their application to vaccine delivery]

Antigen delivery to antigen-presenting cells (APCs) is a key issue in developing effective cancer vaccines. Controlling the tissue distribution of antigens, which are administered in a peptide/protein or DNA form, can increase antigen-specific immune responses, including the induction of cytotoxic T lymphocytes. Heat-shock protein 70 (Hsp70), a member of a highly conserved family of molecular chaperones, forms complexes with a variety of tumor-related antigens via its polypeptide binding domain. Because Hsp70 is taken up by APCs through the recognition by Hsp receptors, such as CD91 and LOX-1, its application to antigen delivery systems has been examined both in experimental and clinical settings. A tissue distribution study revealed that Hsp70 is mainly taken up by the liver, especially by hepatocytes, after intravenous injection in mice. A significant amount of Hsp70 was also delivered to regional lymph nodes when it was injected subcutaneously, supporting the hypothesis that Hsp70 is a natural targeting system to APCs. Model antigens were complexed with or conjugated to Hsp70, by which greater antigen-specific immune responses were achieved. Cytoplasmic delivery of Hsp70-antigen further increased the efficacy of the Hsp70-based vaccines. These findings indicate that effective cancer therapy can be achieved by developing Hsp70-based anticancer vaccines when their tissue and intracellular distribution is properly controlled.

Heat Shock Protein–Based Cancer Vaccines

The ability to duplicate the remarkable success of infectious disease vaccines in cancer, with durably robust and highly specific antitumor immune responses, has been long held as one of the keys in developing true "magic bullet" cancer therapies. This article attempts to explain why cancer vaccines have failed (so far), delineate the increasingly complex barriers that prevent the eliciting of effective antitumor immunity and examines the ability of heat shock protein-based vaccines to overcome these barriers. This article is not a definitive compendium of the huge body of relevant literature but rather focuses on the major concepts underlying active specific immunotherapy in general and heat shock protein vaccines in particular.

HSP70 vaccine in combination with gene therapy with plasmid DNA encoding sPD-1 overcomes immune resistance and suppresses the progression of pulmonary metastatic melanoma

Many tumor immunotherapy efforts are focused on the generation of strong T-cell response against tumor antigens. However, strong T-cell response does not always coincide with tumor rejection, for which upregulated expression of immunoinhibitory molecules may be responsible. In this study, the treatment with heat shock protein 70 (HSP70) vaccine induced an infiltration of T cells into the tumor site as well as the expression of IFN-gamma and IL-2, and delayed lung metastases of tumor, but the tumor progression nonetheless occur finally. We demonstrated that B7-H1 expressed by residual tumor cells was responsible for the resistance of tumor to the therapy with HSP70 vaccine. Blockade of B7-H1 by i.v. injection pPD-1A, a plasmid encoding the extracellular domain of PD-1 (sPD-1), could reverse this resistance and enhance the therapeutic efficacy. To complement these findings, we investigated the gene expression of tumor-infiltrating lymphocytes (TILs) by Real-time PCR analysis, which revealed that the expression of TH1 cytokines IFN-gamma and IL-2 by TIL in the mice treated with HSP70 vaccine in combination with sPD-1 was increased and the expression of negative regulatory molecules IL-10, TGF-beta and foxp3 was decreased, demonstrating that multifunctional properties afforded by the combination therapy can effectively overcome tumor resistance and promote effective antitumor immunity. The in vivo transfection with pPD-1A could be performed as infrequently as once a week and still produce a significant antitumor effect. These findings suggest that the treatment with HSP70 vaccine followed by blockade of tumor-B7-H1 with sPD-1 may provide a promising approach for tumor immunotherapy.

Heat shock proteins HSP70 and GP96: structural insights

Several heat shock proteins (HSPs) act as potent adjuvants for eliciting anti-tumor immunity. HSP-based tumor vaccine strategies have been highly successful in animal models and are undergoing testing in clinical trials. It is generally accepted that HSPs, functioning as chaperones for tumor antigens, elicit tumor-specific adaptive immune responses. HSPs also appear to induce innate immune responses in an antigen-independent fashion. Innate responses generated by HSPs may contribute to anti-tumor immunity. Immunologically active chaperones with anti-tumor activity are referred to as "immunochaperones". Here, we review the studies that address the role of structural domains or regions of the immunochaperones HSP70 and GP96 that may be involved in the induction of adaptive or innate immune responses.

More efficient induction of HLA-A*0201-restricted and carcinoembryonic antigen (CEA)-specific CTL response by immunization with exosomes prepared from heat-stressed CEA-positive tumor cells

PURPOSE

Tumor-derived exosomes are proposed as a new type of cancer vaccine. Heat shock proteins are potent Th1 adjuvant, and heat stress can induce heat shock protein and MHC-I expression in tumor cells, leading to the increased immunogenicity of tumor cells. To improve the immunogenicity of exosomes as cancer vaccine, we prepared exosomes from heat-stressed carcinoembryonic antigen (CEA)-positive tumor cells (CEA+/HS-Exo) and tested the efficacy of these exosomes in the induction of CEA-specific antitumor immunity.

EXPERIMENTAL DESIGN

First, we identified the composition of CEA+/HS-Exo and observed their effects on human dendritic cell maturation. Then, we evaluated their ability to induce a CEA-specific immune response in vivo in HLA-A2.1/Kb transgenic mice and CEA-specific CTL response in vitro in HLA-A*0201+ healthy donors and HLA-A*0201+CEA+ cancer patients.

RESULTS

CEA+/HS-Exo contained CEA and more heat shock protein 70 and MHC-I and significantly induced dendritic cell maturation. Immunization of HLA-A2.1/Kb transgenic mice with CEA+/HS-Exo was more efficient in priming a CEA-specific CTL, and the CTL showed antitumor effect when adoptively transferred to SW480-bearing nude mice. Moreover, in vitro incubation of lymphocytes from HLA-A*0201+ healthy donors and HLA-A*0201+CEA+ cancer patients with CEA+/HS-Exo-pulsed autologous dendritic cells induces HLA-A*0201-restricted and CEA-specific CTL response.

CONCLUSIONS

Our results show that CEA+/HS-Exo has superior immunogenicity than CEA+/Exo in inducing CEA-specific CTL response and suggest that exosomes derived from heat-stressed tumor cells may be used as efficient vaccine for cancer immunotherapy.

Histogram Analysis of Pharmacokinetic Parameters by Bootstrap Resampling from One-point Sampling Data in Animal Experiments

A bootstrap method is proposed for assessing statistical histograms of pharmacokinetic parameters (AUC, MRT, CL and V(ss)) from one-point sampling data in animal experiments. A computer program, MOMENT(BS), written in Visual Basic on Microsoft Excel, was developed for the bootstrap calculation and the construction of histograms. MOMENT(BS) was applied to one-point sampling data of the blood concentration of three physiologically active proteins ((111)In labeled Hsp70, Suc(20)-BSA and Suc(40)-BSA) administered in different doses to mice. The histograms of AUC, MRT, CL and V(ss) were close to a normal (Gaussian) distribution with the bootstrap resampling number (200), or more, considering the skewness and kurtosis of the histograms. A good agreement of means and SD was obtained between the bootstrap and Bailer's approaches. The hypothesis test based on the normal distribution clearly demonstrated that the disposition of (111)In-Hsp70 and Suc(20)-BSA was almost independent of dose, whereas that of (111)In-Suc(40)-BSA was definitely dose-dependent. In conclusion, the bootstrap method was found to be an efficient method for assessing the histogram of pharmacokinetic parameters of blood or tissue disposition data by one-point sampling.

Heat shock protein 70/MAGE-3 fusion protein vaccine can enhance cellular and humoral immune responses to MAGE-3 in vivo

MAGE-3, a member of melanoma antigen (MAGE) gene family, is recognized as an ideal candidate for tumor vaccine because it is expressed in a significant proportion of tumors of various histological types and can induce antigen-specific immune response in vivo. There is now substantial evidence that heat shock proteins HSPs isolated from cancer cells and virus-infected cells can be used as vaccines to produce cancer-specific or virus-specific immunity. In this research, we investigated whether M. tuberculosis HSP70 can be used as vehicle to elicit immune response to its accompanying MAGE-3 protein. A recombinant protein expression vector was constructed that permitted the production of fusion protein linking amino acids 195-314 of MAGE-3 to the C terminus of HSP70. We found that HSP70-MAGE-3 fusion protein can elicit stronger cellular and humoral immune responses against MAGE-3 expressing murine tumor than those elicited by MAGE-3 protein in vivo, which resulted in potent antitumor immunity against MAGE-3-expressing tumors. Covalent linkage of HSP70 to MAGE-3 was necessary to elicit immune response to MAGE-3. These results indicate that linkage of HSP70 to MAGE-3 enhanced immune responses to MAGE-3 in vivo and HSP70 can be exploited to enhance the cellular and humoral immune responses against any attached tumor-specific antigens.

Hsp70-like protein 1 fusion protein enhances induction of carcinoembryonic antigen-specific CD8+ CTL response by dendritic cell vaccine

Heat shock proteins (HSP) have been revealed to interact with antigen-presenting cells and have potent adjuvant capability to induce antigen-specific CD8+ CTL and Th1 responses. Our previous work shows how Hsp70-like protein 1 (Hsp70L1), as a new member of the Hsp70 subfamily, acts as potent Th1 adjuvant. Here, we report the efficient induction of tumor antigen-specific immune response by dendritic cells pulsed with recombinant fusion protein of Hsp70L1 and CEA(576-669) fragment of the carcinoembryonic antigen (CEA) containing CAP-1 (a HLA-A2-restricted CTL epitope). Fusion protein CEA(576-669)-Hsp70L1 can promote dendritic cell maturation and activate dendritic cells to produce cytokines, such as interleukin-12, interleukin-1beta, and tumor necrosis factor-alpha, and chemokines, such as macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, and regulated on activation, normal T expressed and secreted, indicating the adjuvant ability of Hsp70L1 in the fusion protein. CEA-specific HLA-A2.1-restricted CD8+ CTLs either from patients with CEA+/HLA-A2.1+ colon carcinoma or from splenocytes of immunized HLA-A2.1/Kb transgenic mice can be generated more efficiently after stimulations or immunizations with dendritic cells pulsed by CEA(576-669)-Hsp70L1 than with dendritic cells pulsed by CEA(576-669) alone, resulting in secreting more Th1 cytokine IFN-gamma and killing target cells more potently in an antigen-specific and HLA-A2.1-restricted manner. Adoptive transfer of splenocytes from transgenic mice immunized with CEA(576-669)-Hsp70L1-pulsed dendritic cells can inhibit tumor growth and prolong survival in nude mice bearing CEA+/HLA-A2.1+ human colon carcinoma more markedly. Therefore, Hsp70L1 has potent adjuvant effect in form of fusion protein, indicating that Hsp70L1 may be widely used as Th1 adjuvant to prepare antigenic fusion protein for the therapeutics of cancer or infectious diseases.

SUMO wrestling with type 1 diabetes

Post-translational modification of proteins by phosphorylation, methylation, acetylation, or ubiquitylation represent central mechanisms through which various biological processes are regulated. Reversible covalent modification (i.e., sumoylation) of proteins by the small ubiquitin-like modifier (SUMO) has also emerged as an important mechanism contributing to the dynamic regulation of protein function. Sumoylation has been linked to the pathogenesis of a variety of disorders including Alzheimer's disease (AD), Huntington's disease (HD), and type 1 diabetes (T1D). Advances in our understanding of the role of sumoylation suggested a novel regulatory mechanism for the regulation of immune responsive gene expression. In this review, we first update recent advances in the field of sumoylation, then specifically evaluate its regulatory role in several key signaling pathways for immune response and discuss its possible implication in T1D pathogenesis.