CD40, an extracellular receptor for binding and uptake of Hsp70-peptide complexes

DAMPening Tumor Immune Escape: The Role of Endoplasmic Reticulum Chaperones in Immunogenic Chemotherapy

Significance: Preclinical and clinical research in the past two decades has redefined the mechanism of action of some chemotherapeutics that are able to activate the immune system against cancer when cell death is perceived by the immune cells. This immunogenic cell death (ICD) activates antigen-presenting cells (APCs) and T cells to induce immune-mediated tumor clearance. One of the key requirements to achieve this effect is the externalization of the damage-associated molecular patterns (DAMPs), molecules released or exposed by cancer cells during ICD that increase the visibility of the cancer cells by the immune system. Recent Advances: In this review, we focus on the role of calreticulin (CRT) and other endoplasmic reticulum (ER) chaperones, such as the heat-shock proteins (HSPs) and the protein disulfide isomerases (PDIs), as surface-exposed DAMPs. Once exposed on the cell membrane, these proteins shift their role from that of ER chaperone and regulator of Ca2+ and protein homeostasis to act as an immunogenic signal for APCs, driving dendritic cell (DC)-mediated phagocytosis and T-mediated antitumor response. Critical Issues: However, cancer cells exploit several mechanisms of resistance to immune attack, including subverting the exposure of ER chaperones on their surface to avoid immune recognition. Future Directions: Overcoming these mechanisms of resistance represents a potential therapeutic opportunity to improve cancer treatment effectiveness and patient outcomes.

Diversity of extracellular HSP70 in cancer: advancing from a molecular biomarker to a novel therapeutic target

Heat shock protein 70 (HSP70) is a highly conserved protein functioning as a "molecular chaperone", which is integral to protein folding and maturation. In addition to its high expression within cells upon stressful challenges, HSP70 can be translocated to the cell membrane or released from cells in free form or within extracellular vesicles (EVs). Such trafficking of HSP70 is also present in cancer cells, as HSP70 is overexpressed in various types of patient samples across a range of common malignancies, signifying that extracellular HSP70 (eHSP70) can serve as a tumor biomarker. eHSP70 is involved in a broad range of cancer-related events, including cell proliferation and apoptosis, extracellular matrix (ECM) remodeling, epithelial-mesenchymal transition (EMT), angiogenesis, and immune response. eHSP70 can also induce cancer cell resistance to various treatments, such as chemotherapy, radiotherapy, and anti-programmed death-1 (PD-1) immunotherapy. Though the role of eHSP70 in tumors is contradictory, characterized by both pro-tumor and anti-tumor effects, eHSP70 serves as a promising target in cancer treatment. In this review, we comprehensively summarized the current knowledge about the role of eHSP70 in cancer progression and treatment resistance and discussed the feasibility of eHSP70 as a cancer biomarker and therapeutic target.

Cytotoxicity as a form of immunogenic cell death leading to efficient tumor antigen cross-priming

Antigen cross-priming of CD8+ T cells is a critical process necessary for the effective expansion and activation of CD8+ T cells endowed with the ability to recognize and destroy tumor cells. The cross-presentation of tumor antigens to cross-prime CD8+ T cells is mainly mediated, if not only, by a subset of professional antigen-presenting cells termed type-1 conventional dendritic cells (cDC1). The demise of malignant cells can be immunogenic if it occurs in the context of premortem stress. These ways of dying are termed immunogenic cell death (ICD) and are associated with biochemical features favoring cDC1 for the efficient cross-priming of tumor antigens. Immunosurveillance and the success of immunotherapies heavily rely on the ability of cytotoxic immune cells, primarily CD8+ T cells and NK cells, to detect and eliminate tumor cells through mechanisms collectively known as cytotoxicity. Recent studies have revealed the significance of NK- and CTL-mediated cytotoxicity as a prominent form of immunogenic cell death, resulting in mechanisms that promote and sustain antigen-specific immune responses. This review focuses on the mechanisms underlying the cross-presentation of antigens released during tumor cell killing by cytotoxic immune cells, with an emphasis on the role of cDC1 cells. Indeed, cDC1s are instrumental in the effectiveness of most immunotherapies, underscoring the significance of tumor antigen cross-priming in contexts of immunogenic cell death. The notion of the potent immunogenicity of cell death resulting from NK or cytotoxic T lymphocyte (CTL)-mediated cytotoxicity has far-reaching implications for cancer immunotherapy.

Pseudomonas aeruginosa-Derived DnaJ Induces the Expression of IL-1β by Engaging the Interplay of p38 and ERK Signaling Pathways in Macrophages

As members of pathogen-associated molecular patterns, bacterial heat shock proteins (HSPs) are widely recognized for their role in initiating innate immune responses. This study aimed to examine the impact of DnaJ, a homolog of HSP40 derived from Pseudomonas aeruginosa (P. aeruginosa), on the regulation of IL-1β expression in macrophages. We demonstrated that DnaJ modulates macrophages to secrete IL-1β by activating NF-κB and MAPK signaling pathways. Specifically, ERK was identified as a positive mediator for IL-1β expression, while p38 acted as a negative mediator. These results suggest that the reciprocal actions of these two crucial MAPKs play a vital role in controlling IL-1β expression. Additionally, the reciprocal actions of MAPKs were found to regulate the activation of inflammasome-related molecules, including vimentin, NLRP3, caspase-1, and GSDMD. Furthermore, our investigation explored the involvement of CD91/CD40 in ERK signaling-mediated IL-1β production from DnaJ-treated macrophages. These findings emphasize the importance of understanding the signaling mechanisms underlying IL-1β induction and suggest the potential utility of DnaJ as an adjuvant for stimulating inflammasome activation.

DnaJ-induced miRNA-146a negatively regulates the expression of IL-8 in macrophages

As a member of the damage-associated molecular patterns, heat shock proteins (HSPs) are widely recognized for their role in initiating innate immune responses. These highly conserved proteins are expressed ubiquitously in both prokaryotes and eukaryotes. In this study, our aim was to investigate how DnaJ, a HSP40 homolog derived from Pseudomonas aeruginosa (P. aeruginosa), influences the regulation of IL-8 expression in macrophages. Treatment with DnaJ served as a stimulus, inducing a more robust expression of IL-8 compared to other HSP homologs, including DnaK, GroEL, and HtpG. This effect was achieved through the activation of the NF-κB signaling pathway. Interestingly, DnaJ treatment also significantly increased the expression of microRNA-146a (miR-146a), which appears to play a role in modulating the expression of innate defense genes. As a consequence, pre-treatment with DnaJ led to a reduction in the extent of IL-8 induction in response to P. aeruginosa treatment. Notably, this reduction was counteracted by transfection of a miR-146a inhibitor, highlighting the involvement of miR-146a in P. aeruginosa-mediated induction of IL-8 expression. Therefore, this study uncovers the role of DnaJ in triggering the expression of miR-146a, which, in turn, modulates the excessive expression of IL-8 induced by P. aeruginosa infection.

Dendritic cell subsets in cancer immunity and tumor antigen sensing

Dendritic cells (DCs) exhibit a specialized antigen-presenting function and play crucial roles in both innate and adaptive immune responses. Due to their ability to cross-present tumor cell-associated antigens to naïve T cells, DCs are instrumental in the generation of specific T-cell-mediated antitumor effector responses in the control of tumor growth and tumor cell dissemination. Within an immunosuppressive tumor microenvironment, DC antitumor functions can, however, be severely impaired. In this review, we focus on the mechanisms of DC capture and activation by tumor cell antigens and the role of the tumor microenvironment in shaping DC functions, taking advantage of recent studies showing the phenotype acquisition, transcriptional state and functional programs revealed by scRNA-seq analysis. The therapeutic potential of DC-mediated tumor antigen sensing in priming antitumor immunity is also discussed.

Molecular Chaperone Receptors: An Update

Extracellular heat shock proteins (HSP) play important roles in cell signaling and immunity. Many of these effects are mediated by surface receptors expressed on a wide range of cell types, including immune cells. We have investigated the nature of such proteins by cloning candidate receptors into cells (CHO-K1) with the rare property of being null for HSP binding. Using this approach, we have discovered that mammalian and eukaryotic Hsp70 binds avidly to at least three classes of receptor including: (1) c-type lectin receptors (CLR), (2) scavenger receptors (SR) and (3) lectins. However, the structural nature of the receptor-ligand interactions is not currently clear. Hsp70 can bind to LOX-1 (a member of both the CLR and SR), with the c-type lectin binding domain (CTLD), to the SR family members SREC-I and FEEL-1/CLEVER-1/STABILIN-1, which by contrast have arrays of EGF-like repeats in their extracellular domains as well. In this chapter, we will discuss: (1) methods for the discovery of HSP receptors, (2) approaches to the study of individual receptors in cells that contain multiple such receptors and (3) methods for investigating HSP receptor function in vivo.

Characterization of the interactome profiling of Mycoplasma fermentans DnaK in cancer cells reveals interference with key cellular pathways

Chaperone proteins are redundant in nature and, to achieve their function, they bind a large repertoire of client proteins. DnaK is a bacterial chaperone protein that recognizes misfolded and aggregated proteins and drives their folding and intracellular trafficking. Some Mycoplasmas are associated with cancers, and we demonstrated that infection with a strain of Mycoplasma fermentans isolated in our lab promoted lymphoma in a mouse model. Its DnaK is expressed intracellularly in infected cells, it interacts with key proteins to hamper essential pathways related to DNA repair and p53 functions and uninfected cells can take-up extracellular DnaK. We profile here for the first time the eukaryotic proteins interacting with DnaK transiently expressed in five cancer cell lines. A total of 520 eukaryotic proteins were isolated by immunoprecipitation and identified by Liquid Chromatography Mass Spectrometry (LC-MS) analysis. Among the cellular DnaK-binding partners, 49 were shared between the five analyzed cell lines, corroborating the specificity of the interaction of DnaK with these proteins. Enrichment analysis revealed multiple RNA biological processes, DNA repair, chromatin remodeling, DNA conformational changes, protein-DNA complex subunit organization, telomere organization and cell cycle as the most significant ontology terms. This is the first study to show that a bacterial chaperone protein interacts with key eukaryotic components thus suggesting DnaK could become a perturbing hub for the functions of important cellular pathways. Given the close interactions between bacteria and host cells in the local microenvironment, these results provide a foundation for future mechanistic studies on how bacteria interfere with essential cellular processes.

Design of Smart Nanomedicines for Effective Cancer Treatment

Nanomedicine is a novel field of study that involves the use of nanomaterials to address challenges and issues that are associated with conventional therapeutics for cancer treatment including, but not limited to, low bioavailability, low water-solubility, narrow therapeutic window, nonspecific distribution, and multiple side effects of the drugs. Multiple strategies have been exploited to reduce the nonspecific distribution, and thus the side effect of the active pharmaceutical ingredients (API), including active and passive targeting strategies and externally controllable release of the therapeutic cargo. Site-specific release of the drug prevents it from impacting healthy cells, thereby significantly reducing side effects. API release triggers can be either externally applied, as in ultrasound-mediated activation, or induced by the tumor. To rationally design such nanomedicines, a thorough understanding of the differences between the tumor microenvironment versus that of healthy tissues must be pared with extensive knowledge of stimuli-responsive biomaterials. Herein, we describe the characteristics that differentiate tumor tissues from normal tissues. Then, we introduce smart materials that are commonly used for the development of smart nanomedicines to be triggered by stimuli such as changes in pH, temperature, and enzymatic activity. The most recent advances and their impact on the field of cancer therapy are further discussed.

Agents of cancer immunosurveillance: HSPs and dsDNA

Tumor immunosurveillance requires tumor cell-derived molecules to initiate responses through corresponding receptors on antigen presenting cells (APCs) and a specific effector response designed to eliminate the emerging tumor cells. This is supported by evidence from immunodeficient individuals and experimental animals. Recent discoveries suggest that adjuvanticity of tumor-derived heat shock proteins (HSPs) and double-stranded DNA (dsDNA) are necessary for tumor-specific immunity. There is also the obligatory early transfer of tumor antigens to APCs. We argue that tumor-derived HSPs deliver sufficient chaperoned antigen for cross-priming within the quantitative limits set by nascent tumors. In contrast to late-stage tumors, we are only just beginning to understand the unique interactions of the immune system with precancerous/nascent neoplastic cells, which is important for improved cancer prevention measures.

HSP70 Ameliorates Septic Lung Injury via Inhibition of Apoptosis by Interacting with KANK2

Acute lung injury is the most common type of organ damage with high incidence and mortality in sepsis, which is a poorly understood syndrome of disordered inflammation. The aims of this study are to explore whether heat shock protein 70 (HSP70), as a molecular chaperone, attenuates the septic lung injury, and to understand the underlying mechanisms. In our study, treatment with HSP70 ameliorated the survival rate, dysfunction of lung, inflammation, and apoptosis in cecal ligation and puncture (CLP)-treated mice as well as in LPS-treated human alveolar epithelial cells. Furthermore, HSP70 interacted with KANK2, leading to reversed cell viability and reduced apoptosis-inducing factor (AIF) and apoptosis. Additionally, knockdown of KANK2 in epithelial cells and deletion of hsp70.1 gene in CLP mice aggravated apoptosis and tissue damage, suggesting that interaction of KANK2 and HSP70 is critical for protecting lung injury induced by sepsis. HSP70 plays an important role in protection of acute lung injury caused by sepsis through interaction with KANK2 to reduce AIF release and apoptotic cell. HSP70 is a novel potential therapeutic approach for attenuation of septic lung injury.

DnaJ-induced TLR7 mediates an increase in interferons through the TLR4-engaged AKT/NF-κB and JNK signaling pathways in macrophages

Toll-like receptor 7 (TLR7) signaling plays pivotal roles in innate immunity by sensing viral single-stranded RNA thereby triggering inflammatory signaling cascades and eliciting protective antiviral responses. In this study, we found that TLR7 expression is highly induced in response to Pseudomonas aeruginosa (P. aeruginosa) infection in a dose- and time-dependent manner. P. aeruginosa-derived DnaJ, a homolog of HSP40, was identified as a related inducing agent for TLR7 expression, and expression of DnaJ was stimulated when host cells were infected with P. aeruginosa. Interestingly, DnaJ was not involved in mediating an increase in the expression levels of TLR3 and TLR8, other well-known antiviral receptors. The induction of TLR7 in response to DnaJ was mediated by the activation of the AKT (Thr308 and Ser473)/NF-κB and p38/JNK MAPKs signaling pathways, consequently transmitting related signals for the expression of interferons (IFNs). Of note, these antiviral responses were regulated, at least in part, by TLR4, which senses the presence of DnaJ and then promotes downstream activation of the AKT (Ser473)/NF-κB and JNK signaling cascades. Taken together, these results suggest that P. aeruginosa-derived DnaJ is sufficient to promote an increase in TLR7 expression in the TLR4-engaged AKT/NF-κB and JNK signaling pathways, thereby promoting an increased antiviral response through the elevated expression of IFNs.

Heat Shock Protein 70 in Penile Neurovascular Regeneration Requires Cystathionine Gamma-Lyase

Purpose

Diabetes mellitus, one of the major causes of erectile dysfunction, leads to a poor response to phosphodiesterase-5 inhibitors. Heat shock protein 70 (Hsp70), a ubiquitous molecular chaperone, is known to play a role in cell survival and neuroprotection. Here, we aimed to assess whether and how Hsp70 improves erectile function in diabetic mice.

Materials and Methods

Eight-week-old male C57BL/6 mice and Hsp70-Tg mice were used in this study. We injected Hsp70 protein into the penis of streptozotocin (STZ)-induced diabetic mice. Detailed mechanisms were evaluated in WT or Hsp70-Tg mice under normal and diabetic conditions. Primary MCECs, and MPG and DRG tissues were cultivated under normal-glucose and high-glucose conditions.

Results

Using Hsp70-Tg mice or Hsp70 protein administration, we demonstrate that elevated levels of Hsp70 restores erectile function in diabetic mice. We found that cystathionine gamma-lyase (Cse) is a novel target of Hsp70 in this process, showing that Hsp70-Cse acts through the SDF1/HO-1/PI3K/Akt/eNOS/NF-κB p65 pathway to exert its neurovascular regeneration-promoting effects. Coimmunoprecipitation and pull-down assays using mouse cavernous endothelial cells treated with Hsp70 demonstrated physical interactions between Hsp70 and Cse with a dissociation constant of 1.8 nmol/L.

Conclusions

Our findings provide novel and solid evidence that Hsp70 acts through a Cse-dependent mechanism to mediate neurovascular regeneration and restoration of erectile function under diabetic conditions.

The Role of Extracellular HSP70 in the Function of Tumor-Associated Immune Cells

Simple Summary

The intracellular heat shock protein 70 (HSP70) is essential for cells to respond to stress, for instance, by refolding damaged proteins or inhibiting apoptosis. However, in cancer, HSP70 is overexpressed and can translocate to the extracellular milieu, where it emerged as an important modulator of tumor-associated immune cells. By targeting the tumor microenvironment (TME) through different mechanisms, extracellular HSP70 can trigger pro- or anti-tumorigenic responses. Therefore, understanding the pathways and their consequences is crucial for therapeutically targeting cancer and its surrounding microenvironment. In this review, we summarize current knowledge on the translocation of extracellular HSP70. We further elucidate its functions within the TME and provide an overview of potential therapeutic options.

Abstract

Extracellular vesicles released by tumor cells (T-EVs) are known to contain danger-associated molecular patterns (DAMPs), which are released in response to cellular stress to alert the immune system to the dangerous cell. Part of this defense mechanism is the heat shock protein 70 (HSP70), and HSP70-positive T-EVs are known to trigger anti-tumor immune responses. Moreover, extracellular HSP70 acts as an immunogen that contributes to the cross-presentation of major histocompatibility complex (MHC) class I molecules. However, the release of DAMPs, including HSP70, may also induce chronic inflammation or suppress immune cell activity, promoting tumor growth. Here, we summarize the current knowledge on soluble, membrane-bound, and EV-associated HSP70 regarding their functions in regulating tumor-associated immune cells in the tumor microenvironment. The molecular mechanisms involved in the translocation of HSP70 to the plasma membrane of tumor cells and its release via exosomes or soluble proteins are summarized. Furthermore, perspectives for immunotherapies aimed to target HSP70 and its receptors for cancer treatment are discussed and presented.

Recent Advances in the Roles of Autophagy and Autophagy Proteins in Host Cells During Toxoplasma gondii Infection and Potential Therapeutic Implications

Toxoplasma gondii is an obligate intracellular protozoan that can cause encephalitis and retinitis in humans. The success of T. gondii as a pathogen depends in part on its ability to form an intracellular niche (parasitophorous vacuole) that allows protection from lysosomal degradation and parasite replication. The parasitophorous vacuole can be targeted by autophagy or by autophagosome-independent processes triggered by autophagy proteins. However, T. gondii has developed many strategies to preserve the integrity of the parasitophorous vacuole. Here, we review the interaction between T. gondii, autophagy, and autophagy proteins and expand on recent advances in the field, including the importance of autophagy in the regulation of invasion of the brain and retina by the parasite. We discuss studies that have begun to explore the potential therapeutic applications of the knowledge gained thus far.

Diversity of Rainbow Trout Blood B Cells Revealed by Single Cell RNA Sequencing

Simple Summary

Although evolutionarily jawed fish constitute the first group of animals in which a complete adaptive immune system based on immunoglobulins (Igs) is present, many structural immune differences between fish and mammals predict important functional and phenotypical differences between B cells in these two animal groups. However, to date, very few tools are available to study B cell heterogeneity and functionality in fish. Hence, thus far, antibodies targeting the different Igs have been almost exclusively applied as tools to investigate B cell functionality in fish. In the current study, we used the newly developed 10× Genomics single cell RNA sequencing technology and used it to analyze the transcriptional pattern of single B cells from peripheral blood. The results obtained provide us with a transcriptional profile at single cell level of what seem to correspond to different B cell subsets or B cells in different stages of maturation or differentiation. The information provided will not only help us understand the biology of teleost B cells, but also provides us with a repertoire of potential markers that could be used in the future to differentiate trout B cell subsets.

Abstract

Single-cell sequencing technologies capable of providing us with immune information from dozens to thousands of individual cells simultaneously have revolutionized the field of immunology these past years. However, to date, most of these novel technologies have not been broadly applied to non-model organisms such as teleost fish. In this study, we used the 10× Genomics single cell RNA sequencing technology and used it to analyze for the first time in teleost fish the transcriptional pattern of single B cells from peripheral blood. The analysis of the data obtained in rainbow trout revealed ten distinct cell clusters that seem to be associated with different subsets and/or maturation/differentiation stages of circulating B cells. The potential characteristics and functions of these different B cell subpopulations are discussed on the basis of their transcriptomic profile. The results obtained provide us with valuable information to understand the biology of teleost B cells and offer us a repertoire of potential markers that could be used in the future to differentiate trout B cell subsets.

A DM1-doped porous gold nanoshell system for NIR accelerated redox-responsive release and triple modal imaging guided photothermal synergistic chemotherapy

Background

Although many treatments for breast cancer are available, poor tumour targeting limits the effectiveness of most approaches. Consequently, it is difficult to achieve satisfactory results with monotherapies. The lack of accurate diagnostic and monitoring methods also limit the benefits of cancer treatment. The aim of this study was to design a nanocarrier comprising porous gold nanoshells (PGNSs) co-decorated with methoxy polyethylene glycol (mPEG) and trastuzumab (Herceptin®, HER), a therapeutic monoclonal antibody that binds specifically to human epidermal receptor-2 (HER2)-overexpressing breast cancer cells. Furthermore, a derivative of the microtubule-targeting drug maytansine (DM1) was incorporated in the PGNSs.

Methods

Prepared PGNSs were coated with mPEG, DM1 and HER via electrostatic interactions and Au–S bonds to yield DM1-mPEG/HER-PGNSs. SK-BR-3 (high HER2 expression) and MCF-7 (low HER2) breast cancer cells were treated with DM1-mPEG/HER-PGNSs, and cytotoxicity was evaluated in terms of cell viability and apoptosis. The selective uptake of the coated PGNSs by cancer cells and subsequent intracellular accumulation were studied in vitro and in vivo using inductively coupled plasma mass spectrometry and fluorescence imaging. The multimodal imaging feasibility and synergistic chemo-photothermal therapeutic efficacy of the DM1-mPEG/HER-PGNSs were investigated in breast cancer tumour-bearing mice. The molecular mechanisms associated with the anti-tumour therapeutic use of the nanoparticles were also elucidated.

Result

The prepared DM1-mPEG/HER-PGNSs had a size of 78.6 nm and displayed excellent colloidal stability, photothermal conversion ability and redox-sensitive drug release. These DM1-mPEG/HER-PGNSs were taken up selectively by cancer cells in vitro and accumulated at tumour sites in vivo. Moreover, the DM1-mPEG/HER-PGNSs enhanced the performance of multimodal computed tomography (CT), photoacoustic (PA) and photothermal (PT) imaging and enabled chemo-thermal combination therapy. The therapeutic mechanism involved the induction of tumour cell apoptosis via the activation of tubulin, caspase-3 and the heat shock protein 70 pathway. M2 macrophage suppression and anti-metastatic functions were also observed.

Conclusion

The prepared DM1-mPEG/HER-PGNSs enabled nanodart-like tumour targeting, visibility by CT, PA and PT imaging in vivo and powerful tumour inhibition mediated by chemo-thermal combination therapy in vivo. In summary, these unique gold nanocarriers appear to have good potential as theranostic nanoagents that can serve both as a probe for enhanced multimodal imaging and as a novel targeted anti-tumour drug delivery system to achieve precision nanomedicine for cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00824-5.

A single dose of eHSP72 attenuates sepsis severity in mice

High levels of extracellular 72 kDa heat shock protein (eHSP72) can be detected in the serum of septic patients and are associated with increased oxidative profiles and elevated rates of mortality among these patients. However, a possible immunomodulatory role for this protein, resulting in tissue protection during sepsis, has never been assessed. In this study, we investigated whether eHSP72 administration could attenuate the severity of sepsis in a mouse peritonitis model. Animals (90-day-old male C57BL/6J mice) were divided into Sepsis (n = 8) and Sepsis + eHSP72 (n = 9) groups, which both received injections of 20% fecal solution [1 mg/g body weight (wt), intraperitoneal (i.p.)], to trigger peritonitis induced-sepsis, whereas a Control group (n = 7) received a saline injection. eHSP72 was administered (1.33 ng/g body wt) to the Sepsis+eHSP72 group, 12 h after sepsis induction. All animals were evaluated for murine sepsis score (MSS), hemogram, core temperature, and glycemia (before and 4, 12, and 24 h after sepsis induction). Treatment with eHSP72 promoted reduced sepsis severity 24 h after sepsis induction, based on MSS scores (Control = 1.14 ± 1.02; Sepsis = 11.07 ± 7.24, and Sepsis + eHSP72 = 5.62 ± 1.72, P < 0.001) and core temperatures (°C; Control = 37.48 ± 0.58; Sepsis = 35.17 ± 2.88, and Sepsis + eHSP72 = 36.94 ± 2.02; P = 0.006). eHSP72 treatment also limited the oxidative profile and respiratory dysfunction in mice with sepsis. Although sepsis modified glycemic levels and white and red blood cell counts, these variables were not influenced by eHSP72 treatment (P > 0.05). Finally, eHSP72 improved the survival rate after sepsis (P = 0.0371). Together, our results indicated that eHSP72 may ameliorate sepsis severity and possibly improve some sepsis indices in mice.

Astrocyte-derived extracellular vesicles: Neuroreparative properties and role in the pathogenesis of neurodegenerative disorders

Extracellular vesicles (EVs) released by neural cells play an essential role in brain homeostasis and the crosstalk between neural cells and the periphery. EVs are diverse, nano-sized vesicles, which transport proteins, nucleic acids, and lipids between cells over short and long expanses and hence are proficient for modulating the target cells. EVs released from neural cells are implicated in synaptic plasticity, neuron-glia interface, neuroprotection, neuroregeneration, and the dissemination of neuropathological molecules. This review confers the various properties of EVs secreted by astrocytes and their potential role in health and disease with a focus on evolving concepts. Naïve astrocytes shed EVs containing a host of neuroprotective compounds, which include fibroblast growth factor-2, vascular endothelial growth factor, and apolipoprotein-D. Stimulated astrocytes secrete EVs with neuroprotective molecules including heat shock proteins, synapsin 1, unique microRNAs, and glutamate transporters. Well-characterized astrocyte-derived EVs (ADEVs) generated in specific culture conditions and ADEVs that are engineered to carry the desired miRNAs or proteins are likely useful for treating brain injury and neurogenerative diseases. On the other hand, in conditions such as Alzheimer's disease (AD), stroke, Parkinson's disease, Amyotrophic lateral sclerosis (ALS), and other neuroinflammatory conditions, EVs released by activated astrocytes appear to mediate or exacerbate the pathological processes. The examples include ADEVs spreading the dysregulated complement system in AD, mediating motoneuron toxicity in ALS, and stimulating peripheral leukocyte migration into the brain in inflammatory conditions. Strategies restraining the release of EVs by activated astrocytes or modulating the composition of ADEVs are likely beneficial for treating neurodegenerative diseases. Also, periodic analyses of ADEVs in the blood is useful for detecting astrocyte-specific biomarkers in different neurological conditions and for monitoring disease progression and remission with distinct therapeutic approaches.

HSP70 Multi-Functionality in Cancer

The 70-kDa heat shock proteins (HSP70s) are abundantly present in cancer, providing malignant cells selective advantage by suppressing multiple apoptotic pathways, regulating necrosis, bypassing cellular senescence program, interfering with tumor immunity, promoting angiogenesis and supporting metastasis. This direct involvement of HSP70 in most of the cancer hallmarks explains the phenomenon of cancer "addiction" to HSP70, tightly linking tumor survival and growth to the HSP70 expression. HSP70 operates in different states through its catalytic cycle, suggesting that it can multi-function in malignant cells in any of these states. Clinically, tumor cells intensively release HSP70 in extracellular microenvironment, resulting in diverse outcomes for patient survival. Given its clinical significance, small molecule inhibitors were developed to target different sites of the HSP70 machinery. Furthermore, several HSP70-based immunotherapy approaches were assessed in clinical trials. This review will explore different roles of HSP70 on cancer progression and emphasize the importance of understanding the flexibility of HSP70 nature for future development of anti-cancer therapies.

MTBHsp70-exFPR1-pulsed Dendritic Cells Enhance the Immune Response against Cervical Cancer

Cervical cancer is the most common malignancy of the female reproductive system. Dendritic cell (DC)-based immunological therapy is a novel treatment for this cancer. DCs are specialized antigen-presenting cells (APCs) in the human immune system, and they can activate the T cells used in tumor immunological therapy. In this study, we developed a novel immunotherapeutic peptide by linking the Mycobacterium tuberculosis (MTB) heat shock protein 70 (Hsp70) functional peptide to the extracellular domain of FPR1, a protein overexpressed in cervical cancer, to obtain an MTBHsp70-exFPR1 fusion protein. Our experiments confirmed that the MTBHsp70-exFPR1 protein could promote DC maturation and induce the secretion of IL-12p70, IL-1β, and TNF-α. The antitumor effect of human cytotoxic T lymphocytes (CTLs) activated by autologous DCs was assessed in NOG mice. These results indicate that DCs pulsed with MTBHsp70-exFPR1 can enhance antitumor immunity against cervical cancer, providing a novel immune therapeutic strategy.

CD40 forward signalling is a physiological regulator of early sensory axon growth

Multiple members of the tumour necrosis factor superfamily (TNFSF) regulate the growth and branching of neural processes late in development, when neurons are establishing and refining connections. Here, we present the first evidence that a TNFSF member acts much earlier in development, when axons are growing to their targets. CD40L transiently enhanced axon growth from embryonic mouse DRG neurons cultured at this early stage. Early spinal nerves of embryos lacking the CD40L receptor (Cd40^−/− mice) were significantly shorter in vivo than those of Cd40^+/+ littermates. CD40L was synthesized in early DRG targets and was co-expressed with CD40 in early DRG neurons. Whereas CD40L enhanced early axon growth independently of neurotrophins, disruption of a CD40L/CD40 autocrine loop impaired early neurotrophin-promoted axon growth. In marked contrast to the widespread regulation of axon and dendrite growth by CD40L reverse signalling later in development, CD40-Fc, which activates reverse signalling, had no effect on early sensory axon growth. These results suggest that CD40 forward signalling is a novel physiological regulator of early axon growth that acts by target-derived and autocrine mechanisms.

Summary: CD40L, a novel physiological regulator of early sensory axon growth at the stage when sensory axons are growing to their targets, activates CD40 forward signalling by target-derived and autocrine mechanisms.

Heat-Shock Proteins in Neuroinflammation

The heat-shock response, one of the main pro-survival mechanisms of a living organism, has evolved as the biochemical response of cells to cope with heat stress. The most well-characterized aspect of the heat-shock response is the accumulation of a conserved set of proteins termed heat-shock proteins (HSPs). HSPs are key players in protein homeostasis acting as chaperones by aiding the folding and assembly of nascent proteins and protecting against protein aggregation. HSPs have been associated with neurological diseases in the context of their chaperone activity, as they were found to suppress the aggregation of misfolded toxic proteins. In recent times, HSPs have proven to have functions apart from the classical molecular chaperoning in that they play a role in a wider scale of neurological disorders by modulating neuronal survival, inflammation, and disease-specific signaling processes. HSPs are gaining importance based on their ability to fine-tune inflammation and act as immune modulators in various bodily fluids. However, their effect on neuroinflammation processes is not yet fully understood. In this review, we summarize the role of neuroinflammation in acute and chronic pathological conditions affecting the brain. Moreover, we seek to explore the existing literature on HSP-mediated inflammatory function within the central nervous system and compare the function of these proteins when they are localized intracellularly compared to being present in the extracellular milieu.

CD40 in Endothelial Cells Restricts Neural Tissue Invasion by Toxoplasma gondii

Little is known about whether pathogen invasion of neural tissue is affected by immune-based mechanisms in endothelial cells. We examined the effects of endothelial cell CD40 on Toxoplasma gondii invasion of the retina and brain, organs seeded hematogenously. T. gondii circulates in the bloodstream within infected leukocytes (including monocytes and dendritic cells) and as extracellular tachyzoites. After T. gondii infection, mice that expressed CD40 restricted to endothelial cells exhibited diminished parasite loads and histopathology in the retina and brain. These mice also had lower parasite loads in the retina and brain after intravenous (i.v.) injection of infected monocytes or dendritic cells. The protective effect of endothelial cell CD40 was not explained by changes in cellular or humoral immunity, reduced transmigration of leukocytes into neural tissue, or reduced invasion by extracellular parasites. Circulating T. gondii-infected leukocytes (dendritic cells used as a model) led to infection of neural endothelial cells. The number of foci of infection in these cells were reduced if endothelial cells expressed CD40. Infected dendritic cells and macrophages expressed membrane-associated inducible Hsp70. Infected leukocytes triggered Hsp70-dependent autophagy in CD40⁺ endothelial cells and anti-T. gondii activity dependent on ULK1 and beclin 1. Reduced parasite load in the retina and brain not only required CD40 expression in endothelial cells but was also dependent on beclin 1 and the expression of inducible Hsp70 in dendritic cells. These studies suggest that during endothelial cell-leukocyte interaction, CD40 restricts T. gondii invasion of neural tissue through a mechanism that appears mediated by endothelial cell anti-parasitic activity stimulated by Hsp70.

Improving the Clinical Application of Natural Killer Cells by Modulating Signals Signal from Target Cells

Relapsed acute myeloid leukemia (AML) is a significant post-transplant complication lacking standard treatment and associated with a poor prognosis. Cellular therapy, which is already widely used as a treatment for several hematological malignancies, could be a potential treatment alternative. Natural killer (NK) cells play an important role in relapse control but can be inhibited by the leukemia cells highly positive for HLA class I. In order to restore NK cell activity after their ex vivo activation, NK cells can be combined with conditioning target cells. In this study, we tested NK cell activity against KG1a (AML cell line) with and without two types of pretreatment—Ara-C treatment that induced NKG2D ligands (increased activating signal) and/or blocking of HLA–KIR (killer-immunoglobulin-like receptors) interaction (decreased inhibitory signal). Both treatments improved NK cell killing activity. Compared with target cell killing of NK cells alone (38%), co-culture with Ara-C treated KG1a target cells increased the killing to 80%. Anti-HLA blocking antibody treatment increased the proportion of dead KG1a cells to 53%. Interestingly, the use of the combination treatment improved the killing potential to led to the death of 85% of KG1a cells. The combination of Ara-C and ex vivo activation of NK cells has the potential to be a feasible approach to treat relapsed AML after hematopoietic stem cell transplantation.

Early Proteome Shift and Serum Bioactivity Precede Diesel Exhaust-induced Impairment of Cardiovascular Recovery in Spontaneously Hypertensive Rats

Single circulating factors are often investigated to explain air pollution-induced cardiovascular dysfunction, yet broader examinations of the identity and bioactivity of the entire circulating milieu remain understudied. The purpose of this study was to determine if exposure-induced cardiovascular dysfunction can be coupled with alterations in both serum bioactivity and the circulating proteome. Two cohorts of Spontaneously Hypertensive Rats (SHRs) were exposed to 150 or 500 μg/m³ diesel exhaust (DE) or filtered air (FA). In Cohort 1, we collected serum 1 hour after exposure for proteomics analysis and bioactivity measurements in rat aortic endothelial cells (RAECs). In Cohort 2, we assessed left ventricular pressure (LVP) during stimulation and recovery from the sympathomimetic dobutamine HCl, one day after exposure. Serum from DE-exposed rats had significant changes in 66 serum proteins and caused decreased NOS activity and increased VCAM-1 expression in RAECs. While rats exposed to DE demonstrated increased heart rate at the start of LVP assessments, heart rate, systolic pressure, and double product fell below baseline in DE-exposed rats compared to FA during recovery from dobutamine, indicating dysregulation of post-exertional cardiovascular function. Taken together, a complex and bioactive circulating milieu may underlie air pollution-induced cardiovascular dysfunction.

Effect of binding immunoglobulin protein on induction of regulatory B cells with killer phenotype during inflammation and disease

Immune responses result from different immune cells acting in synergy to successfully fight infections. This requires a high degree of regulation to prevent excessive production of inflammatory products leading to other disease forms. Regulatory B cells are classified based on surface immunoglobulin expression. These cells are reported to resolve inflammation during chronic or autoimmune diseases. However, during chronic inflammation, their frequencies have been shown to be affected, and they can be induced by exposure to extracellular binding immunoglobulin protein (BiP). This review focuses on the effects on immune cells by extracellular or secreted BiP during various chronic inflammatory responses. For example, cell stress associated with Mycobacterium tuberculosis infection leads to accumulation of unfolded proteins that subsequently activate BiP and its three signal transducers intracellularly. Furthermore, BiP can be translocated from the endoplasmic reticulum to the extracellular environment where it binds immune cells as an autoantigen and leads to functional changes.

Immune responses during tuberculosis disease require balanced cell interactions. These include antigen-presenting cells, effector cells and regulatory cells. B lymphocytes can mediate regulatory function during chronic diseases and lead to better disease outcome. These specialized cells mediate this function through both surface and soluble protein expression. Their development can be facilitated by different stimuli including binding immunoglobulin protein. This protein resides in the endoplasmic reticulum where it functions in proper protein folding; however, it can escape this location to the extracellular phase, where it affects immune cell function leading to development of regulatory traits on B cells.

Human Mesenchymal Stem Cell Secretome from Bone Marrow or Adipose-Derived Tissue Sources for Treatment of Hypoxia-Induced Pulmonary Epithelial Injury

Alveolar epithelial dysfunction induced by hypoxic stress plays a significant role in the pathological process of lung ischemia-reperfusion injury (IRI). Mesenchymal stem cell (MSC) therapies have demonstrated efficacy in exerting protective immunomodulatory effects, thereby reducing airway inflammation in several pulmonary diseases. Aim: This study assesses the protective effects of MSC secretome from different cell sources, human bone marrow (BMSC) and adipose tissue (ADSC), in attenuating hypoxia-induced cellular stress and inflammation in pulmonary epithelial cells. Methods: Pulmonary epithelial cells, primary rat alveolar epithelial cells (AEC) and A549 cell line were pre-treated with BMSC, or ADSC conditioned medium (CM) and subjected to hypoxia for 24 h. Results: Both MSC-CM improved cell viability, reduced secretion of pro-inflammatory mediators and enhanced IL-10 anti-inflammatory cytokine production in hypoxic injured primary rat AECs. ADSC-CM reduced hypoxic cellular injury by mechanisms which include: inhibition of p38 MAPK phosphorylation and nuclear translocation of subunits in primary AECs. Both MSC-CM enhanced translocation of Bcl-2 to the nucleus, expression of cytoprotective glucose-regulated proteins (GRP) and restored matrix metalloproteinases (MMP) function, thereby promoting repair and cellular homeostasis, whereas inhibition of GRP chaperones was detrimental to cell survival. Conclusions: Elucidation of the protective mechanisms exerted by the MSC secretome is an essential step for maximizing the therapeutic effects, in addition to developing therapeutic targets-specific strategies for various pulmonary syndromes.

Fibronectin aggregates promote features of a classically and alternatively activated phenotype in macrophages

BACKGROUND

Means to promote endogenous remyelination in multiple sclerosis (MS) benefit from insights into the role of inhibitory molecules that preclude remyelination. Fibronectin assembles into aggregates in MS, which impair oligodendrocyte differentiation and remyelination. Microglia and macrophages are required for complete remyelination and normally switch from a pro-inflammatory classical phenotype upon demyelination to a supportive alternative phenotype during remyelination. Here, we investigated the role of fibronectin aggregates in modulating microglia and macrophage behavior and phenotypes.

METHODS

Bone marrow-derived macrophages and microglia from newborn rats were exposed to (a) plasma fibronectin coatings; (b) coatings of deoxycholate-insoluble fibronectin aggregates; (c) interferon-γ (IFNγ) treatment, as an inducer of the pro-inflammatory classically activated phenotype; (d) interleukin-4 (IL-4) treatment, to promote the pro-regenerative anti-inflammatory alternatively activated phenotype; or (e) left unstimulated on uncoated plastic. To examine the in vitro effects of the different stimulations on cell behavior and phenotype, proliferation, phagocytosis, morphology, and pro- and anti-inflammatory features were assessed.

RESULTS

In line with a classically activated phenotype, exposure of microglia and macrophages to both plasma fibronectin and fibronectin aggregates induced an amoeboid morphology and stimulated phagocytosis by macrophages. Furthermore, as observed upon IFNγ treatment, coatings of aggregated, but not plasma fibronectin, promoted nitric oxide release by microglia and macrophages. Remarkably, fibronectin aggregates induced nitric oxide release in an integrin-independent manner. In addition, fibronectin aggregates, but not plasma fibronectin, increased the expression of arginase-1, similarly as observed upon treatment with IL-4. Proteomic analysis revealed that aggregates of fibronectin act as a scaffold for other proteins, including Hsp70 and thrombospondin-1, which may clarify the induction of both pro-inflammatory and anti-inflammatory features in macrophages cultured on fibronectin aggregate, but not plasma fibronectin coatings.

CONCLUSIONS

Macrophages and microglia grown on aggregated fibronectin coatings adopt a distinct phenotype compared to plasma fibronectin coatings, showing pro-inflammatory and anti-inflammatory features. Therefore, the pathological fibronectin aggregates in MS lesions may impair remyelination by promoting and/or retaining several classically activated phenotypic features in microglia and macrophages.

Dendritic Cells in the Cross Hair for the Generation of Tailored Vaccines

Vaccines represent the discovery of utmost importance for global health, due to both prophylactic action to prevent infections and therapeutic intervention in neoplastic diseases. Despite this, current vaccination strategies need to be refined to successfully generate robust protective antigen-specific memory immune responses. To address this issue, one possibility is to exploit the high efficiency of dendritic cells (DCs) as antigen-presenting cells for T cell priming. DCs functional plasticity allows shaping the outcome of immune responses to achieve the required type of immunity. Therefore, the choice of adjuvants to guide and sustain DCs maturation, the design of multifaceted vehicles, and the choice of surface molecules to specifically target DCs represent the key issues currently explored in both preclinical and clinical settings. Here, we review advances in DCs-based vaccination approaches, which exploit direct in vivo DCs targeting and activation options. We also discuss the recent findings for efficient antitumor DCs-based vaccinations and combination strategies to reduce the immune tolerance promoted by the tumor microenvironment.

Korean ginseng extract ameliorates abnormal immune response through the regulation of inflammatory constituents in Sprague Dawley rat subjected to environmental heat stress

Background

Increases in the average global temperature cause heat stress–induced disorders by disrupting homeostasis. Excessive heat stress triggers an imbalance in the immune system; thus protection against heat stress is important to maintain immune homeostasis. Korean ginseng (Panax ginseng Meyer) has been used as a herbal medicine and displays beneficial biological properties.

Methods

We investigated the protective effects of Korean ginseng extracts (KGEs) against heat stress in a rat model. Following acclimatization for 1 week, rats were housed at room temperature for 2 weeks and then exposed to heat stress (40°C/2 h/day) for 4 weeks. Rats were treated with three KGEs from the beginning of the second week to the end of the experiment.

Results

Heat stress dramatically increased secretion of inflammatory factors, and this was significantly reduced in the KGE-treated groups. Levels of inflammatory factors such as heat shock protein 70, interleukin 6, inducible nitric oxide synthase, and tumor necrosis factor-alpha were increased in the spleen and muscle upon heat stress. KGEs inhibited these increases by down-regulating heat shock protein 70 and the associated nuclear factor-κB and mitogen-activated protein kinase signaling pathways. Consequently, KGEs suppressed activation of T-cells and B-cells.

Conclusion

KGEs suppress the immune response upon heat stress and decrease the production of inflammatory cytokines in muscle and spleen. We suggest that KGEs protect against heat stress by inhibiting inflammation and maintaining immune homeostasis.

Molecular Chaperone Receptors

Extracellular heat shock proteins (HSP) play important roles in cell signaling and immunity. Many of these effects are mediated by surface receptors expressed on a wide range of cell types. We have investigated the nature of such proteins by cloning candidate receptors into cells (CHO-K1) with the rare property of being null for HSP binding. Using this approach we have discovered that Hsp70 binds avidly to at least two classes of receptors including: (1) c-type lectin receptors (CLR) and (2) scavenger receptors (SR). However, the structural nature of the receptor-ligand interactions is not clear at this time. Hsp70 can bind to LOX-1 (a member of both the CLR and SR), with the c-type lectin binding domain (CTLD) as well as the SR family members SREC-I and FEEL-1/CLEVER-1/STABILIN-1, which by contrast have arrays of EGF-like repeats in their extracellular domains. In this chapter we will discuss: (1) methods for discovery of HSP receptors, (2) approaches to the study of individual receptors in cells that contain multiple such receptors, and (3) methods for investigating HSP receptor function in vivo.

Endogenous DAMPs, Category I: Constitutively Expressed, Native Molecules (Cat. I DAMPs)

This chapter provides the reader with a collection of endogenous DAMPs in terms of constitutively expressed native molecules. The first class of this category refers to DAMPs, which are passively released from necrotic cells, and includes the most prominent subclasses of high mobility group box I and heat shock proteins. Further subclasses of DAMPs that are passively released from necrotic cells include S100 proteins, nucleic acids, histones, pro-forms of interleukin-1-family members, mitochondria-derived N-formylated peptides, F-actin, and heme. A particular subclass of these passively released DAMPs are molecules, which indirectly activate the inflammasome, including adenosine-5′-triphosphate, monosodium urate crystals, cholesterol crystals, some lipolytic species, and beta-amyloid. All these passively released DAMPs are characterized by their capability to promote necroinflammatory responses. The second class of this Category I refers to molecules, which are exposed on the surface of stressed cells. They include the subclass of phagocytosis-facilitating molecules such as calreticulin, as well as the subclass of MHC-I-related molecules such as MHC-I-related molecule A and B. These DAMPs are capable of inducing the activation of innate lymphoid cells and unconventional T cells. One of these DAMPs, the major histocompatibility complex I-related molecule A, is shown to act as a bona fide transplantation antigen. In sum, the endogenous constitutively expressed native molecules represent an impressive category of DAMPs with extraordinary properties, which play a critical role in the pathogenesis of many human diseases.

Heat shock protein-based therapy as a potential candidate for treating the sphingolipidoses

Lysosomal storage diseases (LSDs) often manifest with severe systemic and central nervous system (CNS) symptoms. The existing treatment options are limited and have no or only modest efficacy against neurological manifestations of disease. We demonstrate that recombinant human heat shock protein 70 (HSP70) improves the binding of several sphingolipid-degrading enzymes to their essential cofactor bis(monoacyl)glycerophosphate in vitro. HSP70 treatment reversed lysosomal pathology in primary fibroblasts from 14 patients with eight different LSDs. HSP70 penetrated effectively into murine tissues including the CNS and inhibited glycosphingolipid accumulation in murine models of Fabry disease (Gla(-/-)), Sandhoff disease (Hexb(-/-)), and Niemann-Pick disease type C (Npc1(-/-)) and attenuated a wide spectrum of disease-associated neurological symptoms in Hexb(-/-) and Npc1(-/-) mice. Oral administration of arimoclomol, a small-molecule coinducer of HSPs that is currently in clinical trials for Niemann-Pick disease type C (NPC), recapitulated the effects of recombinant human HSP70, suggesting that heat shock protein-based therapies merit clinical evaluation for treating LSDs.

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.

New insights to structure and immunological features of Leishmania lipophosphoglycan3

Leishmaniasis is a major public infectious disease caused by the genus Leishmania. No effective drug or vaccination strategy for leishmaniasis has been designed yet. Several intracellular Leishmania antigens have been recognized to serve in vaccination, ensuring long-lasting protection against Leishmania infection. Lipophosphoglican 3 (LPG3) as a member of the heat shock protein 90 family involves in the synthesis of lipophosphoglycan (LPG) and implicates in parasite virulence. Regarding the immunological properties of LPG3 particularly its N-terminal fragment, it would be considered as a favourable adjuvant in Leishmania vaccination.

Heat shock protein 70 potentiates interferon alpha production by plasmacytoid dendritic cells: relevance for cutaneous lupus and vitiligo pathogenesis

BACKGROUND

Plasmacytoid dendritic cells (pDCs) are a subset of dendritic cells specialized in the production of type I interferon (IFN-α/β) and involved in various cutaneous inflammatory and autoimmune disorders, such as cutaneous lupus erythematosus (CLE) and vitiligo. Heat shock proteins (HSPs) are molecular chaperones essential for maintaining cellular functions, but they can act as a danger signal during inflammation.

OBJECTIVES

To decipher the role of HSP70 in the production of IFN-α by pDCs in CLE and vitiligo.

METHODS

Expression of HSP70 and CD123⁺ pDCs was analysed by immunohistochemistry or immunofluorescence in CLE and vitiligo skin samples. Flow cytometry was performed to analyse expression of HSP70 receptors, activation markers on pDCs and DNA uptake by pDCs in the presence of HSP70. The impact of HSP70 on DNA-induced IFN-α secretion by pDCs was evaluated by enzyme-linked immunosorbent assay (ELISA). The effect of IFN-α on chemokine (C-X-C motif) ligand 9 (CXCL9)/10 gene and protein expression by keratinocytes was determined by real-time polymerase chain reaction and ELISA.

RESULTS

Infiltration of pDCs in CLE and progressive vitiligo was primarily located in the epidermis, close to keratinocytes expressing HSP70. In vitro experiments revealed that the pDCs expressing HSP70 receptor Lox-1 (lectin-like oxidized low-density lipoprotein-receptor-1) were able to aggregate HSP70. Exogenous HSP70 induced activation of pDCs and increased the uptake of exogenous DNA. Furthermore, HSP70 potentiated DNA-induced IFN-α production by pDCs. Finally, IFN-α induced expression of CXCL9 and CXCL10 by keratinocytes.

CONCLUSIONS

These data demonstrate that interaction between HSP70 and pDCs in CLE and vitiligo is a prerequisite for the enhancement of IFN-α production, and could be an interesting target.

Protein Folding Mediated by Trigger Factor and Hsp70: New Insights from Single-Molecule Approaches

Chaperones assist in protein folding, but what this common phrase means in concrete terms has remained surprisingly poorly understood. We can readily measure chaperone binding to unfolded proteins, but how they bind and affect proteins along folding trajectories has remained obscure. Here we review recent efforts by our labs and others that are beginning to pry into this issue, with a focus on the chaperones trigger factor and Hsp70. Single-molecule methods are central, as they allow the stepwise process of folding to be followed directly. First results have already revealed contrasts with long-standing paradigms: rather than acting only "early" by stabilizing unfolded chain segments, these chaperones can bind and stabilize partially folded structures as they grow to their native state. The findings suggest a fundamental redefinition of the protein folding problem and a more extensive functional repertoire of chaperones than previously assumed.

Biotechnology approaches to produce potent, self-adjuvanting antigen-adjuvant fusion protein subunit vaccines

Traditional vaccination approaches (e.g. live attenuated or killed microorganisms) are among the most effective means to prevent the spread of infectious diseases. These approaches, nevertheless, have failed to yield successful vaccines against many important pathogens. To overcome this problem, methods have been developed to identify microbial components, against which protective immune responses can be elicited. Subunit antigens identified by these approaches enable the production of defined vaccines, with improved safety profiles. However, they are generally poorly immunogenic, necessitating their administration with potent immunostimulatory adjuvants. Since few safe and effective adjuvants are currently used in vaccines approved for human use, with those available displaying poor potency, or an inability to stimulate the types of immune responses required for vaccines against specific diseases (e.g. cytotoxic lymphocytes (CTLs) to treat cancers), the development of new vaccines will be aided by the availability of characterized platforms of new adjuvants, improving our capacity to rationally select adjuvants for different applications. One such approach, involves the addition of microbial components (pathogen-associated molecular patterns; PAMPs), that can stimulate strong immune responses, into subunit vaccine formulations. The conjugation of PAMPs to subunit antigens provides a means to greatly increase vaccine potency, by targeting immunostimulation and antigen to the same antigen presenting cell. Thus, methods that enable the efficient, and inexpensive production of antigen-adjuvant fusions represent an exciting mean to improve immunity towards subunit antigens. Herein we review four protein-based adjuvants (flagellin, bacterial lipoproteins, the extra domain A of fibronectin (EDA), and heat shock proteins (Hsps)), which can be genetically fused to antigens to enable recombinant production of antigen-adjuvant fusion proteins, with a focus on their mechanisms of action, structural or sequence requirements for activity, sequence modifications to enhance their activity or simplify production, adverse effects, and examples of vaccines in preclinical or human clinical trials.

Influence of Escherichia coli chaperone DnaK on protein immunogenicity

The production of anti-drug antibodies can impact significantly upon the safety and efficacy of biotherapeutics. It is known that various factors, including aggregation and the presence of process-related impurities, can modify and augment the immunogenic potential of proteins. The purpose of the investigations reported here was to characterize in mice the influence of aggregation and host cell protein impurities on the immunogenicity of a humanized single-chain antibody variable fragment (scFv), and mouse albumin. Host cell protein impurities within an scFv preparation purified from Escherichia coli displayed adjuvant-like activity for responses to the scFv in BALB/c strain mice. The 70 000 MW E. coli chaperone protein DnaK was identified as a key contaminant of scFv by mass spectrometric analysis. Preparations of scFv lacking detectable DnaK were spiked with recombinant E. coli DnaK to mimic the process-related impurity. Mice were immunized with monomeric and aggregated preparations, with and without 0·1% DnaK by mass. Aggregation alone enhanced IgM and IgG2a antibody responses, but had no significant effect on total IgG or IgG1 responses. The addition of DnaK further enhanced IgG and IgG2a antibody responses, but only in the presence of aggregated protein. DnaK was shown to be associated with the aggregated scFv by Western blot analysis. Experiments with mouse albumin showed an overall increase in immunogenicity with protein aggregation alone, and the presence of DnaK increased the vigour of the IgG2a antibody response further. Collectively these data reveal that DnaK has the potential to modify and enhance immunogenicity when associated with aggregated protein.

Putative model for heat shock protein 70 complexation with receptor of advanced glycation end products through fluorescence proximity assays and normal mode analyses

Extracellular heat shock protein 70 (HSP70) is recognized by receptors on the plasma membrane, such as Toll-like receptor 4 (TLR4), TLR2, CD14, and CD40. This leads to activation of nuclear factor-kappa B (NF-κB), release of pro-inflammatory cytokines, enhancement of the phagocytic activity of innate immune cells, and stimulation of antigen-specific responses. However, the specific characteristics of HSP70 binding are still unknown, and all HSP70 receptors have not yet been described. Putative models for HSP70 complexation to the receptor for advanced glycation endproducts (RAGEs), considering both ADP- and ATP-bound states of HSP70, were obtained through molecular docking and interaction energy calculations. This interaction was detected and visualized by a proximity fluorescence-based assay in A549 cells and further analyzed by normal mode analyses of the docking complexes. The interacting energy of the complexes showed that the most favored docking situation occurs between HSP70 ATP-bound and RAGE in its monomeric state. The fluorescence proximity assay presented a higher number of detected spots in the HSP70 ATP treatment, corroborating with the computational result. Normal-mode analyses showed no conformational deformability in the interacting interface of the complexes. Results were compared with previous findings in which oxidized HSP70 was shown to be responsible for the differential modulation of macrophage activation, which could result from a signaling pathway triggered by RAGE binding. Our data provide important insights into the characteristics of HSP70 binding and receptor interactions, as well as putative models with conserved residues on the interface area, which could be useful for future site-directed mutagenesis studies.

Recombinant heat shock protein 70 functional peptide and alpha-fetoprotein epitope peptide vaccine elicits specific anti-tumor immunity

Alpha-fetoprotein (AFP) is a marker of hepatocellular carcinoma (HCC) and serves as a target for immunotherapy. However, current treatments targeting AFP are not reproducible and do not provide complete protection against cancer. This issue may be solved by developing novel therapeutic vaccines with enhanced immunogenicity that could effectively target AFP-expressing tumors. In this study, we report construction of a therapeutic peptide vaccine by linking heat shock protein 70 (HSP70) functional peptide to the AFP epitope to obtain HSP70-P/AFP-P. This novel peptide was administered into BALB/c mice to observe the effects. Quantification of AFP-specific CD8 + T cells that secrete IFN-γ in these mice via ELISPOT revealed the synergistic effects of HSP70-P/AFP-P with increased numbers of AFP-specific CD8 + T cells. Similarly, ELISA analysis showed increased granzyme B and perforin released by natural killer cells. Moreover, in vitro cytotoxic T-lymphocyte assays and in vivo tumor preventive experiments clearly showed the higher antitumor effects of HSP70-P/AFP-P against AFP-expressing tumors. These results show that treatment of BALB/c mice with HSP70-P/AFP-P induced stronger T-cells responses and improved protective immunity. Our data suggest that HSP70-P/AFP-P may be used as a therapeutic approach in the treatment of AFP-expressing cancers.

Heat Shock Proteins (HSP): Future Trends in Cancer Immunotherapy

Heat Shock Proteins (HSPs) are a large family of highly conserved proteins involved in assisting protein folding and unfolding in the cells. HSPs are expressed constitutively as well as inducibly and, interacting with antigen presenting cells, induce the expression of various cytokines and chemokines as well as the maturation and migration of dendritic cells, thus acting themselves as cytokines. HSP-chaperoned antigenic peptides are also generated within the tumor cells. Such chaperoned peptides are released in the extra cellular medium with an association of HSPs by cell stress, death or tumor cell lyses. HSP-peptide complexes from extra cellular medium are taken up by antigen presenting cells through CD91 receptor and are represented or cross-presented by their MHC class I molecules for specific anti-tumor immune response. In addition, HSPs expressed on the cell surface of tumor cells stimulate αβ T-cells and γδ T-cells as well as natural killer (NK) cells that are first-line defense mechanisms. In this manner, HSPs have the ability to stimulate both arms of the effecter mechanism of the immune system. These unique immunological attributes of HSPs are presently becoming the basis for tumor immunotherapy. Tumor-derived HSP-peptide complexes have been demonstrated to serve as anti-tumor vaccines. To date various approaches of vaccination using HSPs have been developed and tested clinically. These HSP-based vaccine approaches can be combined with hyperthermia and CTLA-4 blockade to enhance their anti-tumor potentiality.

Heat Shock Protein-Peptide and HSP-Based Immunotherapies for the Treatment of Cancer

Intracellular residing heat shock proteins (HSPs) with a molecular weight of approximately 70 and 90 kDa function as molecular chaperones that assist folding/unfolding and transport of proteins across membranes and prevent protein aggregation after environmental stress. In contrast to normal cells, tumor cells have higher cytosolic heat shock protein 70 and Hsp90 levels, which contribute to tumor cell propagation, metastasis, and protection against apoptosis. In addition to their intracellular chaperoning functions, extracellular localized and membrane-bound HSPs have been found to play key roles in eliciting antitumor immune responses by acting as carriers for tumor-derived immunogenic peptides, as adjuvants for antigen presentation, or as targets for the innate immune system. The interaction of HSP–peptide complexes or peptide-free HSPs with receptors on antigen-presenting cells promotes the maturation of dendritic cells, results in an upregulation of major histocompatibility complex class I and class II molecules, induces secretion of pro- and anti-inflammatory cytokines, chemokines, and immune modulatory nitric oxides, and thus integrates adaptive and innate immune phenomena. Herein, we aim to recapitulate the history and current status of HSP-based immunotherapies and vaccination strategies in the treatment of cancer.

Promoting Neuronal Tolerance of Diabetic Stress: Modulating Molecular Chaperones

The etiology of diabetic peripheral neuropathy (DPN) involves an interrelated series of metabolic and vascular insults that ultimately contribute to sensory neuron degeneration. In the quest to pharmacologically manage DPN, small-molecule inhibitors have targeted proteins and pathways regarded as "diabetes specific" as well as others whose activity are altered in numerous disease states. These efforts have not yielded any significant therapies, due in part to the complicating issue that the biochemical contribution of these targets/pathways to the progression of DPN does not occur with temporal and/or biochemical uniformity between individuals. In a complex, chronic neurodegenerative disease such as DPN, it is increasingly appreciated that effective disease management may not necessarily require targeting a pathway or protein considered to contribute to disease progression. Alternatively, it may prove sufficiently beneficial to pharmacologically enhance the activity of endogenous cytoprotective pathways to aid neuronal tolerance to and recovery from glucotoxic stress. In pursuing this paradigm shift, we have shown that modulating the activity and expression of molecular chaperones such as heat shock protein 70 (Hsp70) may provide translational potential for the effective medical management of insensate DPN. Considerable evidence supports that modulating Hsp70 has beneficial effects in improving inflammation, oxidative stress, and glucose sensitivity. Given the emerging potential of modulating Hsp70 to manage DPN, the current review discusses efforts to characterize the cytoprotective effects of this protein and the benefits and limitations that may arise in drug development efforts that exploit its cytoprotective activity.

Fever and the thermal regulation of immunity: the immune system feels the heat

Fever is a cardinal response to infection that has been conserved in warm-blooded and cold-blooded vertebrates for more than 600 million years of evolution. The fever response is executed by integrated physiological and neuronal circuitry and confers a survival benefit during infection. In this Review, we discuss our current understanding of how the inflammatory cues delivered by the thermal element of fever stimulate innate and adaptive immune responses. We further highlight the unexpected multiplicity of roles of the pyrogenic cytokine interleukin-6 (IL-6), both during fever induction and during the mobilization of lymphocytes to the lymphoid organs that are the staging ground for immune defence. We also discuss the emerging evidence suggesting that the adrenergic signalling pathways associated with thermogenesis shape immune cell function.