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Heat shock proteins (HSP) like Hsp60, Hsp70 and gp96 act directly on antigen-presenting cells (APC), e.g. by inducing the secretion of cytokines. Here we analyzed the impact of Hsp60 on the antigen-specific activation of CD8+ T cells in a TCR transgenic system. Hsp60 induced low amounts of IFN-γ in the absence of antigenic peptide; however, the release of IFN-γ is increased by a factor of 3–10 following the addition of Hsp60 to purified populations of OT-1 [ovalbumin (OVA)257–264/H2-Kb-restricted] T cells and antigen-pulsed peritoneal exudate cells (PEC) as APC. This effect is strictly correlated with the PEC ability to produce IL-12. In contrast, antigen-specific IL-2 secretion and T cell proliferation was not changed in the presence of Hsp60. Hsp60-containing OT-1 T cell cultures produced IFN-γ even when the number of antigenic MHC class I complexes was too low to be stimulatory and could not be detected with specific mAb. Hsp60, thus, acts as a catalyzing molecule to initiate both innate and adaptive immune responses, and its presence (e.g. during an infection with cellular destruction) has direct consequences for the activation of otherwise `ignorant' antigen-specific T cells. [ABSTRACT FROM PUBLISHER]

Naked DNA vaccines represent an attractive approach for generating antigen-specific immunity because of their stability and simplicity of delivery. There are particular concerns with DNA vaccines however, such as potential integration into the host genome, cell transformation, and limited potency. The usage of DNA-based alphaviral RNA replicons (suicidal DNA vectors) may alleviate the concerns of integration or transformation since suicidal DNA vectors eventually cause lysis of transfected cells. To improve further the potency of suicidal DNA vaccines, we evaluated the effect of linking Mycobacterium tuberculosis heat shock protein 70 (Hsp70) to human papillomavirus type 16 (HPV-16) E7 as a model antigen on antigen-specific immunity generated by a DNA-based Semliki Forest virus (SFV) RNA vector, pSCA1. Our results indicated that this suicidal DNA vaccine containing E7/Hsp70 fusion genes generated significantly higher E7-specific T cell-mediated immune responses than vaccines containing the wild-type E7 gene in vaccinated mice. More importantly, this fusion converted a less effective vaccine into one with significant potency against established E7expressing metastatic tumors. The antitumor effect was predominantly CD8-dependent. These results indicate that linkage of Hsp70 to the antigen may greatly enhance the potency of suicidal DNA vaccines. [ABSTRACT FROM AUTHOR]

Major histocompatibility complex (MHC) class I molecules bind antigenic peptides that are translocated from the cytosol into the endoplasmic reticulum by the transporter associated with antigen processing. MHC class I loading independent of this transporter also exists and involves peptides derived from exogenously acquired antigens. Thus far, a detailed characterization of the intracellular compartments involved in this pathway is lacking. In the present study, we have used the model system in which peptides derived from measles virus protein F are presented to cytotoxic T cells by Blymphoblastoid cells that lack the peptide transporter. Inhibition of T cell activation by the lysosomotropic drug ammoniumchloride indicated that endocytic compartments were involved in the class I presentation of this antigen. Using immunoelectron microscopy, we demonstrate that class I molecules and virus protein F co-localized in multivesicular endosomes and lysosomes. Surprisingly, these compartments expressed high levels of class II molecules, and further characterization identified them as MHC class II compartments. In addition, we show that class I molecules co-localized with class II molecules on purified exosomes, the internal vesicles of multivesicular endosomes that are secreted upon fusion of these endosomes with the plasma membrane. Finally, dendritic cells, crucial for the induction of primary immune responses, also displayed class I in endosomes and on exosomes. [ABSTRACT FROM AUTHOR]

The Trypanosoma cruzi HSP70 recombinant protein has the capacity to stimulate splenocytes or lymph node cells from naive mice in a non-haplotype-restricted way. The proliferative response is abolished by proteinase K digestion and by specific anti-HSP70 antibodies. The induced stimulation index was maximal after 24 h of incubation with the protein. This stimulation leads to cell death in a Fas–Fas ligand-independent way. The phenotype of the expanded cells was CD3+ TCRαβ+ CD4+. HSP70-responsive cells express a broad range of cytokines including IFN-γ, IL-2 and tumor necrosis factor-α. After 48 h of incubation with HSP70 there was a significant increase in relative intracellular levels of CD3 TCRαβ receptors. The expanded CD4+ cell population expressed CD25; however, in contrast to concanavalin A-treated culture, delayed CD44 expression was observed. [ABSTRACT FROM PUBLISHER]

We analyzed the interaction between a bacterial cell wall protein and dendritic cells (DCs). Outer membrane protein A from Klebsiella pneumoniae (kpOmpA) specifically bound to professional antigen presenting cells and was endocytosed by immature DCs via a receptor-dependent mechanism. kpOmpA signaled through Toll-like receptor 2, induced DCs to produce interleukin 12 and induced maturation of DCs. Whole antigen that was coupled to kpOmpA and injected into mice was taken up by DCs and delivered to the conventional cytosolic MHC class I presentation pathway. kpOmpA also primed antigen-specific CD8+ CTLs in the absence of CD4+ T cell help or adjuvant and elicited therapeutic immunity to antigen-expressing tumors. Thus, OmpA belongs to a class of proteins that are able to elicit CTL responses to exogenous antigen. [ABSTRACT FROM AUTHOR]

Coexpression of cytokine genes together with antigen-encoding genes in DNA vaccination vectors can increase humoral and cellular immune responses and may steer them in a Th1 or Th2 direction. In this study, the modulatory effect of interleukin (IL)-2, IL-4, and interferon (IFN)-γ coexpressed with the 60-kDa heat shock protein (Hsp60) of Yersinia enterocolitica O:8 (Y-Hsp60) was studied. DNA vaccination with y-hsp60 evoked specific humoral and cellular immune responses as well as reduction of the splenic bacterial load upon challenge with Y. enterocolitica in a mouse infection model. Coexpression of IL-2 or IFN-γ enhanced Y. enterocolitica-specific total IgG ( P < 0.05) and IgG2a antibody responses. Coexpression of IFN-γ also improved the proliferative T cell responses upon stimulation with Y-Hsp60. A reduction of the splenic bacterial load as compared with the plasmid encoding Y-Hsp60 only was found for the IFN-γ coexpressing vector. Thus, coexpression of cytokine genes such as IFN-γ in DNA vaccination vectors might improve immunity and help to overcome the side effects of standard adjuvants. [ABSTRACT FROM AUTHOR]

We have utilized a free-solution/isoelectric focusing technique (FS-IEF) to obtain fractions rich in multiple chaperone proteins from clarified A20 tumor lysates. Vaccines prepared from chaperone-rich fractions are capable of providing protective immunity in mice subsequently challenged intravenously with the same A20 B cell leukemia cells. This protection is at least equal to that provided by purified, tumor-derived heat-shock protein 70, which was the best chaperone immunogen in our hands against this aggressive murine leukemia model. Dosage escalation studies, however, revealed that increasing vaccine dosages actually abrogated the protective effects. The physical nature of the enriched chaperones indicates that they are associated in complexes, which may have implications for their function. FS-IEF is relatively simple, rapid, and efficient, thus making combined multi-chaperone therapy feasible. [ABSTRACT FROM AUTHOR]

CD40 and CD40 ligand (CD40L) have been implicated as important molecules for the transformation of nonactivated antigen-presenting cells (APC) into cells that are potent inducers of cytotoxic T lymphocyte (CTL) immunity. The onset of a successful immune response lies within the control of the CD4+ T helper cells which, after specific antigen recognition, can up-regulate CD40L and subsequently activate APC through CD40 signaling. Triggering of CD40 with antibodies in vivo can replace the need for CD40L-expressing CD4+ T helper cells for cross-priming of CTL. Blocking of CD40–CD40L interactions can also have profound effects on the generation of T cell immunity. Interestingly, differential involvement of CD40/CD40L in immune responses can be observed between various immunological sites in the body. In most sites of the periphery interruption of CD40-CD40L interactions can lead to the induction of T cell tolerance whereas in mucosal tissues this interruption can lead to abrogation of T cell tolerance. Furthermore, in vivo CD40 activation can convert specific T cell tolerance following peptide vaccination into efficient T cell priming. Thus intervention of CD40–CD40L interactions can result in enhancement or down-modulation of T cell reactivity and therefore modulation of these interactions may form the foundation of new treatment modalities directed against malignancies, allergies, organ rejections and autoimmunity. [ABSTRACT FROM AUTHOR]

Antigen presenting cells (APCs) can take up exogenous antigenic peptides chaperoned by heat shock protein gp96 and re-present them through the endogenous pathway on their major histocompatibility class I molecules. The high efficiency of this process has been attributed previously to a receptor for gp96 on APCs. The CD91 molecule (also called α2-macroglobulin receptor or the low density lipoprotein?related protein) is shown here to be a cell surface receptor for the heat shock protein gp96. CD91 binds gp96 directly, rather than through another ligand for CD91. The previously known CD91 ligand, α2-macroglobulin, inhibits re-presentation of gp96-chaperoned antigenic peptides by macrophages, as do antibodies to CD91. As gp96 is exclusively intracellular and is released as a result of necrotic but not apoptotic cell death, we propose that CD91 acts as a sensor for necrotic cell death. [ABSTRACT FROM AUTHOR]

The survival of patients with cancer has improved steadily but incrementally over the last century, with the advent of effective anticancer treatments such as chemotherapy and radiotherapy. However, the majority of patients with metastatic disease will not be cured by these measures and will eventually die of their disease. New and more effective methods of treating these patients are required urgently. The immune system is a potent force for rejecting transplanted organs or microbial pathogens, but effective spontaneous immunologically induced cancer remissions are very rare. In recent years, much has been discovered about the mechanisms by which the immune system recognizes and responds to cancers. The specific antigens involved have now been defined in many cases. Improved adjuvants are available. Means by which cancer cells overcome immunological attack can be exploited and overcome. Most importantly, the immunological control mechanisms responsible for initiating and maintaining an effective immune response are now much better understood. It is now possible to manipulate immunological effector cells or antigen-presenting cells ex vivo in order to induce an effective antitumour response. At the same time, it is possible to recruit other aspects of the immune system, both specific (e.g. antibody responses) and innate (natural killer cells and granulocytes). [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are potent antigen-presenting cells specialized to initiate T-cell immunity. The development of methods to generate large numbers of DCs has facilitated their application for immunotherapy. Recent studies have demonstrated the safety and immunogenicity of DCs in humans and have begun to outline the durability, kinetics, and nature of the elicited T-cell responses. However, DC-based immunotherapy remains a challenge and several parameters need to be examined to optimize immune responses, in order to maximize clinical efficacy against cancer and infectious diseases. [ABSTRACT FROM AUTHOR]

Focuses on the application of bone marrow-derived dendritic cells (DC) in cancer immunotherapy. Definition and function of DC; Sources of DC; Discussion on DC life cycle; Approaches to antigen delivery of DC.

Discusses the development and immunoregulatory functions of dendritic cells. Heterogeneity of dendritic cell subsets; Link between antigen capture, migration and maturation; Information on major histocompatibility complex; Discussion on antigen presentation and T cell activation; Regulation of B lymphocytes.

Focuses on the physiologic implications of heat shock proteins (hsp). Level of control of antigen-specific immune responses; Effects of hsp on antigen processing and presentation; Immune modulation by heat shock proteins.

Radiation therapy (RT) can induce an immunogenic variant of regulated cell death that can initiate clinically relevant tumor-targeting immune responses. Immunogenic cell death (ICD) is accompanied by the exposure and release of damage-associated molecular patterns (DAMPs), chemokine release, and stimulation of type I interferon (IFN-I) responses. In recent years, intensive research has unraveled major mechanistic aspects of RT-induced ICD and has resulted in the identification of immunogenic factors that are released by irradiated tumor cells. However, so far, only a limited number of studies have searched for potential biomarkers that can be used to predict if irradiated tumor cells undergo ICD that can elicit an effective immunogenic anti-tumor response. In this article, we summarize the available literature on potential biomarkers of RT-induced ICD that have been evaluated in cancer patients. Additionally, we discuss the clinical relevance of these findings and important aspects that should be considered in future studies. [ABSTRACT FROM AUTHOR]

The 70 kDa heat shock protein (HSP70) is a stress-inducible protein that has been shown to protect the brain from various nervous system injuries. It allows cells to withstand potentially lethal insults through its chaperone functions. Its chaperone properties can assist in protein folding and prevent protein aggregation following several of these insults. Although its neuroprotective properties have been largely attributed to its chaperone functions, HSP70 may interact directly with proteins involved in cell death and inflammatory pathways following injury. Through the use of mutant animal models, gene transfer, or heat stress, a number of studies have now reported positive outcomes of HSP70 induction. However, these approaches are not practical for clinical translation. Thus, pharmaceutical compounds that can induce HSP70, mostly by inhibiting HSP90, have been investigated as potential therapies to mitigate neurological disease and lead to neuroprotection. This review summarizes the neuroprotective mechanisms of HSP70 and discusses potential ways in which this endogenous therapeutic molecule could be practically induced by pharmacological means to ultimately improve neurological outcomes in acute neurological disease. [ABSTRACT FROM AUTHOR]

The discovery of inflammasomes has enriched our knowledge in the pathogenesis of multiple inflammatory diseases. The NLR pyrin domain-containing protein 3 (NLRP3) has emerged as the most versatile and well-characterized inflammasome, consisting of an intracellular multi-protein complex that acts as a central driver of inflammation. Its activation depends on a tightly regulated two-step process, which includes a wide variety of unrelated stimuli. It is therefore not surprising that the specific regulatory mechanisms of NLRP3 inflammasome activation remain unclear. Inflammasome-mediated inflammation has become increasingly important in acute pancreatitis, an inflammatory disorder of the pancreas that is one of the fatal diseases of the gastrointestinal tract. This review presents an update on the progress of research into the contribution of the NLRP3 inflammasome to acute pancreatic injury, examining the mechanisms of NLRP3 activation by multiple signaling events, the downstream interleukin 1 family of cytokines involved and the current state of the literature on NLRP3 inflammasome-specific inhibitors. [ABSTRACT FROM AUTHOR]

Cell death resistance is a key feature of tumor cells. One of the main anticancer therapies is increasing the susceptibility of cells to death. Cancer cells have developed a capability of tumor immune escape. Hence, restoring the immunogenicity of cancer cells can be suggested as an effective approach against cancer. Accumulating evidence proposes that several anticancer agents provoke the release of danger-associated molecular patterns (DAMPs) that are determinants of immunogenicity and stimulate immunogenic cell death (ICD). It has been suggested that ICD inducers are two different types according to their various activities. Here, we review the well-characterized DAMPs and focus on the different types of ICD inducers and recent combination therapies that can augment the immunogenicity of cancer cells. [ABSTRACT FROM AUTHOR]

The safety and feasibility of dendritic cell (DC)-based immunotherapies in cancer management have been well documented after more than twenty-five years of experimentation, and, by now, undeniably accepted. On the other hand, it is equally evident that DC-based vaccination as monotherapy did not achieve the clinical benefits that were predicted in a number of promising preclinical studies. The current availability of several immune modulatory and targeting approaches opens the way to many potential therapeutic combinations. In particular, the evidence that the immune-related effects that are elicited by immunogenic cell death (ICD)-inducing therapies are strictly associated with DC engagement and activation strongly support the combination of ICD-inducing and DC-based immunotherapies. In this review, we examine the data in recent studies employing tumor cells, killed through ICD induction, in the formulation of anticancer DC-based vaccines. In addition, we discuss the opportunity to combine pharmacologic or physical therapeutic approaches that can promote ICD in vivo with in situ DC vaccination. [ABSTRACT FROM AUTHOR]

The article focuses on the role of CD91 and heat shock proteins in psoriasis. Heat shock proteins (HSPs) have an enormous significance in the dynamic interplay between innate and adaptive immunity and provides new insights into mechanisms underlying chronic inflammation, including the necrotic response to infection and cancer. The history of this particular story began with chance events in 1962 when the temperature on an incubator full of fruit flies was inadvertently turned up to 60 degrees Celsius. Under light microscopy, the salivary gland chromosomes of the fruit flies, thus 'heat-shocked', showed dilated puffs indicative of transcriptional activity at discrete loci.

Heat shock proteins interact with antigen-presenting cells through their receptor, CD91, eliciting a cascade of events including maturation, activation and representation of chaperoned foreign peptides with class I molecules on their surface. In turn, this facilitates recognition of non-self leading to induction of a cytotoxic T cell response. The abundance of heat shock proteins in tumours and their presence in virion coats makes them attractive propositions for use in antitumour and antiviral strategies. [ABSTRACT FROM AUTHOR]

National cancer databases document that melanoma is the most aggressive and deadly cutaneous malignancy with worldwide increasing incidence in the Caucasian population. Around 10% of melanomas occur in families. Several germline mutations were identified that might help to indicate individuals at risk for preventive interventions and early disease detection. More than 50% of sporadic melanomas carry mutations in Ras/Raf/mitogen-activated protein kinase (MAPK/MEK) pathway, which may represent aims of novel targeted therapies. Despite advances in targeted therapies and immunotherapies, the outcomes in metastatic tumor are still unsatisfactory. Here, we review animal models that help our understanding of melanoma development and treatment, including non-vertebrate, mouse, swine, and other mammal models, with an emphasis on those with spontaneously developing melanoma. Special attention is paid to the melanoma-bearing Libechov minipig (MeLiM). This original swine model of hereditary metastatic melanoma enables studying biological processes underlying melanoma progression, as well as spontaneous regression. Current histological, immunohistochemical, biochemical, genetic, hematological, immunological, and skin microbiome findings in the MeLiM model are summarized, together with development of new therapeutic approaches based on tumor devitalization. The ongoing study of molecular and immunological base of spontaneous regression in MeLiM model has potential to bring new knowledge of clinical importance. [ABSTRACT FROM AUTHOR]

Infection is restrained by the concerted activation of tissue-resident and circulating immune cells. Recent discoveries have demonstrated that tissue-resident lymphocyte subsets, comprised of innate lymphoid cells (ILCs) and unconventional T cells, have vital roles in the initiation of primary antiviral responses. Via direct and indirect mechanisms, ILCs and unconventional T cell subsets play a critical role in the ability of the immune system to mount an effective antiviral response through potent early cytokine production. In this review, we will summarize the current knowledge of tissue-resident lymphocytes during initial viral infection and evaluate their redundant or nonredundant contributions to host protection or virus-induced pathology. [ABSTRACT FROM AUTHOR]