Yin–Yang regulation of autoimmunity by DCs

Graft-versus-host disease prophylaxis: Pathophysiology-based review on current approaches and future directions

Graft-versus-host disease (GvHD) was first described in 1959, since then major efforts have been made in order to understand its physiopathology and animal models have played a key role. Three steps, involving different pathways, have been recognised in either acute and chronic GvHD, identifying them as two distinct entities. In order to reduce GvHD incidence and severity, prophylactic measures were added to transplant protocols. The combination of a calcineurin inhibitor (CNI) plus an antimetabolite remains the standard of care. Better knowledge of GvHD pathophysiology has moved this field forward and nowadays different drugs are being used on a daily basis. Improving GvHD prophylaxis is a major goal as it would translate into less non-relapse mortality and better overall survival. As compared to CNI plus methotrexate the combination of CNI plus mycophenolate mophetil (MMF) allows us to obtain similar results in terms of GvHD incidence but a lower toxicity rate in terms of neutropenia or mucositis. The use of ATG has been related to a lower risk of acute and chronic GvHD in prospective randomized trials as well as the use of posttransplant Cyclophosphamide, with no or marginal impact on overall survival but with an improvement in GvHD-relapse free survival (GRFS). The use of sirolimus has been related to a lower risk of acute GvHD and significantly influenced overall survival in one prospective randomized trial. Other prospective trials have evaluated the use of receptors such as CCR5 or α4β7 to avoid T-cells trafficking into GvHD target organs, cytokine blockers or immune check point agonists. Also, epigenetic modifiers have shown promising results in phase II trials. Attention should be paid to graft-versus-leukemia, infections and immune recovery before bringing new prophylactic strategies to clinical practice. Although the list of novel agents for GvHD prophylaxis is growing, randomized trials are still lacking for many of them.

Experimental autoimmune encephalomyelitis in the common marmoset: a translationally relevant model for the cause and course of multiple sclerosis

Aging Western societies are facing an increasing prevalence of chronic autoimmune-mediated inflammatory disorders (AIMIDs) for which treatments that are safe and effective are scarce. One of the main reasons for this situation is the lack of animal models, which accurately replicate clinical and pathological aspects of the human diseases. One important AIMID is the neuroinflammatory disease multiple sclerosis (MS), for which the mouse experimental autoimmune encephalomyelitis (EAE) model has been frequently used in preclinical research. Despite some successes, there is a long list of experimental treatments that have failed to reproduce promising effects observed in murine EAE models when they were tested in the clinic. This frustrating situation indicates a wide validity gap between mouse EAE and MS. This monography describes the development of an EAE model in nonhuman primates, which may help to bridge the gap.

Merits and complexities of modeling multiple sclerosis in non-human primates: implications for drug discovery

INTRODUCTION

The translation of scientific discoveries made in animal models into effective treatments for patients often fails, indicating that currently used disease models in preclinical research are insufficiently predictive for clinical success. An often-used model in the preclinical research of autoimmune neurological diseases, multiple sclerosis in particular, is experimental autoimmune encephalomyelitis (EAE). Most EAE models are based on genetically susceptible inbred/SPF mouse strains used at adolescent age (10-12 weeks), which lack exposure to genetic and microbial factors which shape the human immune system. Areas covered: Herein, the authors ask whether an EAE model in adult non-human primates from an outbred conventionally-housed colony could help bridge the translational gap between rodent EAE models and MS patients. Particularly, the authors discuss a novel and translationally relevant EAE model in common marmosets (Callithrix jacchus) that shares remarkable pathological similarity with MS. Expert opinion: The MS-like pathology in this model is caused by the interaction of effector memory T cells with B cells infected with the γ1-herpesvirus (CalHV3), both present in the pathogen-educated marmoset immune repertoire. The authors postulate that depletion of only the small subset (<0.05%) of CalHV3-infected B cells may be sufficient to limit chronic inflammatory demyelination.

Autoimmune Aspects of Neurodegenerative and Psychiatric Diseases: A Template for Innovative Therapy

Neurodegenerative and psychiatric diseases (NPDs) are today's most important group of diseases, surpassing both atherosclerotic cardiovascular disease and cancer in morbidity incidence. Although NPDs have a dramatic impact on our society because of their high incidence, mortality, and severe debilitating character, remarkably few effective interventions have become available. The current treatments, if available, comprise the lifelong intake of general immunosuppressants to delay disease progression or neurotransmitter antagonists/agonists to dampen undesired behaviors. The long-term usage of such medication, however, coincides with often severe adverse side effects. There is, therefore, an urgent need for safe and effective treatments for these diseases. Here, we discuss that many NPDs coincide with subtle chronic or flaring brain inflammation sometimes escalating with infiltrations of lymphocytes in the inflamed brain parts causing mild to severe or even lethal brain damage. Thus, NPDs show all features of autoimmune diseases. In this review, we postulate that NPDs resemble autoimmune-driven inflammatory diseases in many aspects and may belong to the same disease spectrum. Just like in autoimmune diseases, NPD symptoms basically are manifestations of a chronic self-sustaining inflammatory process with detrimental consequences for the patient. Specific inhibition of the destructive immune responses in the brain, leaving the patient's immune system intact, would be the ultimate solution to cure patients from the disease. To reach this goal, the primary targets, e.g., the primary self-antigens (pSAgs) of the patient's chronic (auto)immune response, need to be identified. For a few major NPDs, immunological studies led to the identification of the pSAgs involved in the autoimmune damage of specific brain parts. However, further research is needed to complete the list of pSAgs for all NPDs. Such immunological studies will not only provide crucial insights into NPD pathogenesis but also ultimately enable the development of a new generation of safe and effective immunotherapies for NPDs. Interventions that will dramatically improve the life expectancy and quality of life of individual patients and, moreover, will significantly reduce the health-care costs of the society in general.

Lessons for lupus from tumour necrosis factor blockade

Systemic lupus erythematosus (SLE) is a systemic non-organ specific autoimmune disease associated with multiple autoantibodies targeting autoantigens from the nucleus. Given the complex pathophysiology of SLE and the role of TNF alpha in that disease, modulation of TNF alpha (in SLE or non-SLE patients) using TNF blockers could either be detrimental or beneficial in some patients. In this review we will focus on lupus autoantibodies and clinical manifestations after TNF blockade in SLE patients and conversely on drug-induced-SLE in non-SLE patients. Some hypotheses regarding the mechanism of induction of autoantibodies in RA patients treated with TNF blockers are proposed.

Myelin oligodendrocyte glycoprotein has a dual role in T cell autoimmunity against central nervous system myelin

Background

Myelin oligodendrocyte glycoprotein (MOG) is a candidate primary target of the autoimmune attack on the central nervous system (CNS) in multiple sclerosis (MS). However, the physiological function of MOG has been unclear for a long time.

Objective

We propose that MOG has a central role in the regulation of tolerance and autoimmunity.

Conclusion

The interaction of MOG with DC-SIGN, an innate antigen receptor of myeloid antigen-presenting cells (m-APCs), present inside the CNS (microglia) or in draining lymph nodes (dendritic cells; DCs), keeps these cells in an immature/tolerogenic state. We postulate that this tolerogenic mechanism may be disturbed in MS by unknown factors.

Immune profile of an atypical EAE model in marmoset monkeys immunized with recombinant human myelin oligodendrocyte glycoprotein in incomplete Freund's adjuvant

Background

Experimental autoimmune encephalomyelitis (EAE) in the common marmoset monkey (Callithrix jacchus) is a relevant preclinical model for translational research into immunopathogenic mechanisms operating in multiple sclerosis (MS). Prior studies showed a core pathogenic role of T and B cells specific for myelin oligodendrocyte glycoprotein (MOG). However, in those studies, the quality of the response against MOG epitopes was strongly biased by bacterial antigens in the complete Freund’s adjuvant (CFA), in which the immunizing recombinant human (rh) MOG protein had been formulated. In response to the need of a more refined EAE model, we have tested whether disease could also be induced with rhMOG in incomplete Freund’s adjuvant (IFA).

Method

Marmosets were immunized with rhMOG emulsified in IFA in the dorsal skin. Monkeys that did not develop neurological deficit were given booster immunizations at 28-day interval with the same antigen preparation. In a second experiment, three marmoset twin pairs were sensitized against MOG peptides in IFA to study a possibility for suppressive activity towards pathogenic T cells directed against the encephalitogenic epitope MOG40-48.

Results

Despite the absence of strong danger signals in the rhMOG/IFA inoculum, all monkeys developed clinically evident EAE symptoms. Moreover, in all monkeys, demyelinated lesions were present in the white matter and in two cases also in the cortical grey matter. Immune profiling at height of the disease showed a dominant T cell response against the overlapping peptides 14–36 and 24–46, but reactivity against the pathogenically most relevant peptide 34–56 was conspicuously absent. In the second experiment, there was an indication for a possible suppressive mechanism.

Conclusions

Immunization of marmoset monkeys with rhMOG in IFA elicits clinical EAE in all animals. Moreover, rhMOG contains pathogenic and regulatory epitopes, but the pathogenic hierarchy of rhMOG epitopes is strongly influenced by the adjuvant in which the protein is formulated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0378-5) contains supplementary material, which is available to authorized users.

The primate autoimmune encephalomyelitis model; a bridge between mouse and man

Introduction

Multiple sclerosis (MS) is an enigmatic autoimmune-driven inflammatory/demyelinating disease of the human central nervous system (CNS), affecting brain, spinal cord, and optic nerves. The cause of the disease is not known and the number of effective treatments is limited. Despite some clear successes, translation of immunological discoveries in the mouse experimental autoimmune encephalomyelitis (EAE) model into effective therapies for MS patients has been difficult. This translation gap between MS and its elected EAE animal model reflects the phylogenetic distance between humans and their experimental counterpart, the inbred/specific pathogen free (SPF) laboratory mouse.

Objective

Here, we discuss that important new insights can be obtained into the mechanistic basis of the therapy paradox from the study of nonhuman primate EAE (NHP-EAE) models, the well-validated EAE model in common marmosets (Callithrix jacchus) in particular.

Interpretation

Data presented in this review demonstrate that due to a considerable immunological and pathological overlap with mouse EAE on one side and MS on the other, the NHP EAE model can help us bridge the translation gap.

Detection of anti-cytokine antibodies and their clinical relevance

Cytokines regulate many aspects of cell growth and differentiation and play pivotal roles in the orchestration of immune defence against invading pathogens. Though 'self' proteins, they are potentially immunogenic and can give rise to anti-cytokine autoantibodies (aCA). The main foci of the article are a critical summary of the various methodologies applied for detecting and measuring aCA and a broad review of studies of the occurrence, characterization and clinical relevance of aCA in normal healthy individuals, patients with autoimmune diseases or microbial infections and aCA in patients whose disease is treated with recombinant cytokine products. The need for technical and methodological improvement of assays, including validation and standardization, together with approaches to harmonize calculation and reporting of results is also discussed.

Analytical tools for the study of cellular glycosylation in the immune system

It is becoming increasingly clear that glycosylation plays important role in intercellular communication within the immune system. Glycosylation-dependent interactions are crucial for the innate and adaptive immune system and regulate immune cell trafficking, synapse formation, activation, and survival. These functions take place by the cis or trans interaction of lectins with glycans. Classical immunological and biochemical methods have been used for the study of lectin function; however, the investigation of their counterparts, glycans, requires very specialized methodologies that have been extensively developed in the past decade within the Glycobiology scientific community. This mini-review intends to summarize the available technology for the study of glycan biosynthesis, its regulation and characterization for their application to the study of glycans in immunology.

Bridging innate and adaptive antitumor immunity targeting glycans

Effective immunotherapy for cancer depends on cellular responses to tumor antigens. The role of major histocompatibility complex (MHC) in T-cell recognition and T-cell receptor repertoire selection has become a central tenet in immunology. Structurally, this does not contradict earlier findings that T-cells can differentiate between small hapten structures like simple glycans. Understanding T-cell recognition of antigens as defined genetically by MHC and combinatorially by T cell receptors led to the “altered self” hypothesis. This notion reflects a more fundamental principle underlying immune surveillance and integrating evolutionarily and mechanistically diverse elements of the immune system. Danger associated molecular patterns, including those generated by glycan remodeling, represent an instance of altered self. A prominent example is the modification of the tumor-associated antigen MUC1. Similar examples emphasize glycan reactivity patterns of antigen receptors as a phenomenon bridging innate and adaptive but also humoral and cellular immunity and providing templates for immunotherapies.

Dendritic cells pulsed with malondialdehyde modified low density lipoprotein aggravate atherosclerosis in Apoe(-/-) mice

OBJECTIVE

Atherosclerosis is an inflammatory disease involving activation of adaptive and innate immune responses to modified lipoproteins. Dendritic cells (DCs), which are professional antigen-presenting cells that activate T cells, are present in atherosclerotic lesions but their role for atherosclerosis-related immunity is unclear.

METHODS AND RESULTS

To evaluate the role of DC in atherosclerosis, DCs pulsed with malondialdehyde modified low density lipoprotein (MDA-LDL) were transferred into Apoe(-/-) mice. The extent of disease was measured in the aortic root and was compared to that in animals treated with Keyhole Limpet Hemocyanin (KLH) pulsed DCs and to untreated animals. Mice receiving MDA-LDL pulsed DCs showed significantly larger atherosclerotic lesions compared to controls, with increased inflammation in the lesions and antigen-specific immune responses. Furthermore, MDA-LDL administration in complete Freund's adjuvant, which is atheroprotective, led to the induction of regulatory T cells whereas MDA-LDL-DCs treatment did not, suggesting that modulation of immune properties can result in different effects on atherosclerosis.

CONCLUSIONS

DCs presenting components of LDL promote specific immunity to their antigen, increase lesion inflammation and accelerate atherosclerosis.

Clinical, pathological, and immunologic aspects of the multiple sclerosis model in common marmosets (Callithrix jacchus)

The efficacy of many new immunomodulatory therapies for multiple sclerosis (MS) patients has often been disappointing, reflecting our incomplete understanding of this enigmatic disease. There is a growing awareness that, at least in part, there may be limited applicability to the human disease of results obtained in the widely studied MS model experimental autoimmune encephalomyelitis in rodents. This review describes the experimental autoimmune encephalomyelitis model developed in a small neotropical primate, the common marmoset (Callithrix jacchus). The model has features including clinicopathologic correlation patterns, lesion heterogeneity, immunologic mechanisms, and disease markers that more closely mimic the human disease. Several unique features of experimental autoimmune encephalomyelitis in marmosets, together with their outbred nature and close genetic and immunologic similarities to humans, create an attractive experimental model for translational research into MS, particularly for the preclinical evaluation of new biologic therapeutic molecules that cannot be investigated in rodents because of their species specificity. Moreover, this model provides new insights into possible pathogenetic mechanisms in MS.

Abundant extracellular myelin in the meninges of patients with multiple sclerosis

BACKGROUND

In multiple sclerosis (MS) myelin debris has been observed within MS lesions, in cerebrospinal fluid and cervical lymph nodes, but the route of myelin transport out of the brain is unknown. Drainage of interstitial fluid from the brain parenchyma involves the perivascular spaces and leptomeninges, but the presence of myelin debris in these compartments has not been described.

AIMS

To determine whether myelin products are present in the meninges and perivascular spaces of MS patients.

METHODS

Formalin-fixed brain tissue containing meninges from 29 MS patients, 9 non-neurological controls, 6 Alzheimer's disease, 5 stroke, 5 meningitis and 7 leucodystrophy patients was investigated, and immunohistochemically stained for several myelin proteins [proteolipid protein (PLP), myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)]. On brain material from MS patients and (non)neurological controls, PLP immunostaining was used to systematically investigate the presence of myelin debris in the meninges, using a semiquantitative scale.

RESULTS

Extensive extracellular presence of myelin particles, positive for PLP, MBP, MOG and CNPase in the leptomeninges of MS patients, was observed. Myelin particles were also observed in perivascular spaces of MS patients. Immunohistochemical double-labelling for macrophage and dendritic cell markers and PLP confirmed that the vast majority of myelin particles were located extracellularly. Extracellular myelin particles were virtually absent in meningeal tissue of non-neurological controls, Alzheimer's disease, stroke, meningitis and leucodystrophy cases.

CONCLUSIONS

In MS leptomeninges and perivascular spaces, abundant extracellular myelin can be found, whereas this is not the case for controls and other neurological disease. This may be relevant for understanding sustained immunogenicity or, alternatively, tolerogenicity in MS.

Preclinical assessment of therapeutic antibodies against human CD40 and human interleukin-12/23p40 in a nonhuman primate model of multiple sclerosis

BACKGROUND

Proinflammatory cytokines, such as interleukin (IL)-12 and IL-23, and costimulatory molecules on antigen-presenting cells (APC), such as CD40, are critical to autoreactive T cell activation by APC, and hence, are considered relevant targets of therapy for immune-mediated inflammatory diseases (IMID).

OBJECTIVE

The current review discusses the preclinical evaluation of two novel immunotherapeutic monoclonal antibodies (mAbs), one directed against human IL-12/23p40 and the other against CD40. As the antibodies only recognize their target molecule in primates, the efficacy could not be tested in rodent models.

RESULTS

As a preclinical IMID model for the in vivo evaluation of both mAbs, we have used the experimental autoimmune/allergic encephalomyelitis (EAE) model in common marmoset monkeys (Callithrix jacchus). Both mAbs show beneficial activities in the EAE model when administered early in disease development as well as after the onset of brain inflammation. The treatment effects were evaluated using a combination of quantitative magnetic resonance imaging and a series of ex vivo and immunopathological evaluations.

CONCLUSION

The promising effects during ongoing disease in a relevant preclinical IMID model illustrate the potential of these two antibodies as treatment of IMID, in particular for multiple sclerosis on which disease EAE has been modeled.

Insulin administration confers diabetes-preventive properties to NOD mice derived dendritic cells

Administration of autoantigen can be of value for prevention of autoimmune diabetes and it has been speculated that the control point of dendritic cells (DC) for the induction of peripheral tolerance may be highly relevant. We examined the properties of DC associated with immune suppression in NOD mice by insulin injection subcutaneously and the ability of which to suppress diabetes transfer by diabetogenic effector cells in secondary NOD-SCID recipients. Our data showed that the surface expressions of MHC II and CD86 on NOD-derived DC were increased after insulin treatment compared with those on PBS controlled mice. The dendritic cells with a mature phenotype and increased MLR stimulation adoptively transferred immune tolerogenic effects in secondary NOD-SCID mice, which were associated with significant greater IL-10, TGF-beta production and CD4(+)CD25(+)T differentiation from splenocytes compared with NOD-SCID control recipients. Moreover, treatment with DC remarkably decreased the incidence of diabetes in secondary recipients. These results suggest that a subtype of DC generated by insulin subcutaneous treated NOD mice confers potential protection from diabetes through polarizing the immune response towards a Th2 regulatory pathway.

The perfect mix: recent progress in adjuvant research

Developing efficient and safe adjuvants for use in human vaccines remains both a challenge and a necessity. Past approaches have been largely empirical and generally used a single type of adjuvant, such as aluminium salts or emulsions. However, new vaccine targets often require the induction of well-defined cell-mediated responses in addition to antibodies, and thus new immunostimulants are required. Recent advances in basic immunology have elucidated how early innate immune signals can shape subsequent adaptive responses and this, coupled with improvements in biochemical techniques, has led to the design and development of more specific and focused adjuvants. In this Review, I discuss the research that has made it possible for vaccinologists to now be able to choose between a large panel of adjuvants, which potentially can act synergistically, and combine them in formulations that are specifically adapted to each target and to the relevant correlate(s) of protection.

C3d binding to the myelin oligodendrocyte glycoprotein results in an exacerbated experimental autoimmune encephalomyelitis

The complement system is known to contribute to demyelination in multiple sclerosis and experimental autoimmune encephalomyelitis. However, there are few data concerning the natural adjuvant effect of C3d on the humoral response when it binds to myelin Ags. This study addresses the effect of C3d binding to the myelin oligodendrocyte glycoprotein (MOG) in the induction of experimental autoimmune encephalomyelitis in C57BL/6J mice. Immunization with human MOG coupled to C3d was found to accelerate the appearance of clinical signs of the disease and to enhance its severity compared with MOG-immunized mice. This finding was correlated with an increased infiltration of leukocytes into the central nervous system accompanied by increased complement activation and associated with areas of demyelination and axonal loss. Furthermore, B cell participation in the pathogenesis of the disease was determined by their increased capacity to act as APCs and to form germinal centers. Consistent with this, the production of MOG-specific Abs was found to be enhanced following MOG/C3d immunization. These results suggest that binding of C3d to self-Ags could increase the severity of an autoimmune disease by enhancing the adaptive autoimmune response.

Carbohydrate recognition systems in autoimmunity

The immune system is a complex functional network of diverse cells and soluble molecules orchestrating innate and adaptive immunity. Biological information, to run these intricate interactions, is not only stored in protein sequences but also in the structure of the glycan part of the glycoconjugates. The spatially accessible carbohydrate structures that contribute to the cell's glycome are decoded by versatile recognition systems in order to maintain the immune homeostasis of an organism. Microbial carbohydrate structures are recognized by pathogen associated molecular pattern (PAMP) receptors of innate immunity including C-type lectins such as MBL, the tandem-repeat-type macrophage mannose receptor, DC-SIGN or dectin-1 of dendritic cells, certain TLRS or the TCR of NKT cells. Natural autoantibodies, a long known effector branch of this network-based operation, are effective to home in on non-self and self-glycosylation also. The recirculating pool of mammalian immune cells is recruited to inflammatory sites by a reaction pathway involving the self-carbohydrate-binding selectins as initial recognition step. Galectins, further key sensors reading the high-density sugar code, exert regulatory functions on activated T cells, among other activities. Autoimmune diseases are being associated with defined changes of glycosylation. This correlation deserves to be thoroughly studied on the levels of structural mimicry and dysregulation as well as effector molecules to devise innovative anti-inflammatory strategies. This review briefly summarizes data on sensor systems for carbohydrate epitopes and implications for autoimmunity.

Liposomal vaccines--targeting the delivery of antigen

Vaccines that can prime the adaptive immune system for a quick and effective response against a pathogen or tumor cells, require the generation of antigen (Ag)-specific memory T and B cells. The unique ability of dendritic cells (DCs) to activate naïve T cells, implies a key role for DCs in this process. The generation of tumor-specific CD8(+) cytotoxic T cells (CTLs) is dependent on both T cell stimulation with Ag (peptide-MHC-complexes) and costimulation. Interestingly, tumor cells that lack expression of T cell costimulatory molecules become highly immunogenic when transfected to express such molecules on their surface. Adoptive immunotherapy with Ag-pulsed DCs also is a strategy showing promise as a treatment for cancer. The use of such cell-based vaccines, however, is cumbersome and expensive to use clinically, and/or may carry risks due to genetic manipulations. Liposomes are particulate vesicular lipid structures that can incorporate Ag, immunomodulatory factors and targeting molecules, and hence can serve as potent vaccines. Similarly, Ag-containing plasma membrane vesicles (PMV) derived from tumor cells can be modified to incorporate a T cell costimulatory molecule to provide both TCR stimulation, and costimulation. PMVs also can be modified to contain IFN-gamma and molecules for targeting DCs, permitting delivery of both Ag and a DC maturation signal for initiating an effective immune response. Our results show that use of such agents as vaccines can induce potent anti-tumor immune responses and immunotherapeutic effects in tumor models, and provide a strategy for the development of effective vaccines and immunotherapies for cancer and infectious diseases.

Role of Dendritic Cells in Sjogren's Syndrome

Sjögren's syndrome (SS) is a chronic inflammatory and lymphoproliferative autoimmune disease of unknown aetiology. It is characterised by progressive mononuclear cell infiltration of the salivary and lacrimal glands and a decreased glandular secretion, resulting in dryness of the mouth and eyes (xerostomia and keratoconjunctivitis sicca, respectively). Dendritic cells (DC) are considered to be the most potent antigen-presenting cells. Because of their central role in initiating an immune response while maintaining tolerance, impaired function of these cells might lead to the break of peripheral tolerance and initiation of immune responses to self-antigens. This review will focus on the possible role of DC in SS.

Emerging evidence indicates that physiologically relevant thermal stress regulates dendritic cell function

Elevations in temperature that are associated with inflammation or fever have been linked to improved survival from infections, enhanced immunological functions, and increased control of tumor growth. Over the past few years, several groups have begun to explore the possible linkage among these observations and have tested the hypothesis that various immune cells are especially sensitive to thermal stimulation. However, relatively little is known regarding the effects of thermal stimulation on antigen presenting cells (APCs), such as dendritic cells (DCs). Very recently, several groups have begun to examine the ability of thermal stimuli to regulate the function of these cells which are known to play a pivotal role in the efficacy of vaccines and other immunotherapies. In this review, we summarize what has been discovered about the role of mild thermal stress in regulating various Dendritic cell (DC) activities. Excitingly, it appears that mild elevations of temperature have the potential to enhance antigen uptake, activation associated migration, maturation, cytokine expression and T cell stimulatory activity of DCs. While these studies reveal that the timing, temperature and duration of heating is important, they also set the stage for essential questions that now need to be investigated regarding the molecular mechanisms by which elevated temperatures regulate DC function. With this information, we may soon be able to maximize the strategic use of thermal therapy as an adjuvant, i.e., combining its use with cancer immunotherapies such as vaccines, which depend upon the function of DCs. Several possible strategies and timepoints involving the clinical application of hyperthermia in combination with immunotherapy are presented.

Dendritic-cell-associated C-type lectin 2 (DCAL-2) alters dendritic-cell maturation and cytokine production

Dendritic-cell (DC)-associated C-type lectin receptors (CLRs) take up antigens to present to T cells and regulate DC functions. DCAL-2 is a CLR with a cytosolic immunoreceptor tyrosine-based inhibitory motif (ITIM), which is restricted to immature DCs (iDCs), monocytes, and CD1a+ DCs. Cross-linking DCAL-2 on iDCs induced protein tyrosine phosphorylation and MAPK activation as well as receptor internalization. To test if DCAL-2 is involved in DC maturation and cytokine expression, we stimulated iDCs with anti-DCAL-2 mAb with or without LPS, zymosan, or CD40L. While anti-DCAL-2 did not induce iDCs to mature, it did up-regulate CCR7 expression and IL-6 and IL-10 production. DCAL-2 signals augmented DC maturation induced by LPS or zymosan, increasing both CCR7 and DC-LAMP expression. Of interest, DCAL-2 ligation had the opposite effects on TLR versus CD40L signaling: anti-DCAL-2 suppressed TLR-induced IL-12 expression, but significantly enhanced CD40L-induced IL-12 production. DCAL-2 ligation also suppressed the ability of TLR-matured DCs to induce IFN-gamma-secreting Th1 cells but augmented the capacity of CD40L-matured DCs to polarize naive T cells into Th1 cells. Thus, DCAL-2 may program DCs differently depending on whether DCs are signaled via TLRs or by T cells. DCAL-2 may be a potential immunotherapeutic target for modulating autoimmune diseases or for developing vaccines.

Non-human primate models of experimental autoimmune encephalomyelitis: Variations on a theme

Despite years of intensive research into multiple sclerosis (MS) scientists have not yet succeeded in developing an absolute therapy for the treatment of this disabling disease of the human central nervous system. The wide immunological gap between inbred rodent strains and the heterogeneous human population is probably the single most important factor that hampers the translation of scientific principles developed in rodents into effective therapies for MS. Because of the closer immunological proximity to humans, non-human primates provide useful experimental models that may help to bridge this gap. Here we review the models of experimental autoimmune encephalomyelitis in rhesus macaques and common marmosets. We will discuss the salient points of the models and suggest how these may represent the spectrum of inflammatory demyelinating diseases of the central nervous system in humans.

Modeling human arthritic diseases in nonhuman primates

Models of rheumatoid arthritis (RA) in laboratory animals are important tools for research into pathogenic mechanisms and the development of effective, safe therapies. Rodent models (rats and mice) have provided important information about the pathogenic mechanisms. However, the evolutionary distance between rodents and humans hampers the translation of scientific principles into effective therapies. The impact of the genetic distance between the species is especially seen with treatments based on biological molecules, which are usually species-specific. The outbred nature and the closer anatomical, genetic, microbiological, physiological, and immunological similarity of nonhuman primates to humans may help to bridge the wide gap between inbred rodent strain models and the heterogeneous RA patient population. Here we review clinical, immunological and pathological aspects of the rhesus monkey model of collagen-induced arthritis, which has emerged as a reproducible model of human RA in nonhuman primates.

A live and inactivated Chlamydia trachomatis mouse pneumonitis strain induces the maturation of dendritic cells that are phenotypically and immunologically distinct

The intracellular bacterial pathogen Chlamydia trachomatis is a major cause of sexually transmitted disease worldwide. While protective immunity does appear to develop following natural chlamydial infection in humans, early vaccine trials using heat-killed C. trachomatis resulted in limited and transient protection with possible enhanced disease during follow-up. Thus, immunity following natural infection with live chlamydia may differ from immune responses induced by immunization with inactivated chlamydia. To study this differing immunology, we used murine bone marrow-derived dendritic cells (DC) to examine DC maturation and immune effector function induced by live and UV-irradiated C. trachomatis elementary bodies (live EBs and UV-EB, respectively). DC exposed to live EBs acquired a mature DC morphology; expressed high levels of major histocompatibility complex (MHC) class II, CD80, CD86, CD40, and ICAM-1; produced elevated amounts of interleukin-12 and tumor necrosis factor alpha; and were efficiently recognized by Chlamydia-specific CD4+ T cells. In contrast, UV-EB-pulsed DC expressed low levels of CD40 and CD86 but displayed high levels of MHC class II, ICAM-1, and CD80; secreted low levels of proinflammatory cytokines; and exhibited reduced recognition by Chlamydia-specific CD4+ T cells. Adoptive transfer of live EB-pulsed DC was more effective than that of UV-EB-pulsed DC at protecting mice against challenge with live C. trachomatis. The expression of DC maturation markers and immune protection induced by UV-EB could be significantly enhanced by costimulation of DC ex vivo with UV-EB and oligodeoxynucleotides containing cytosine phosphate guanosine; however, the level of protection was significantly less than that achieved by using DC pulsed ex vivo with viable EBs. Thus, exposure of DC to live EBs results in a mature DC phenotype which is able to promote protective immunity, while exposure to UV-EB generates a semimature DC phenotype with less protective potential. This result may explain in part the differences in protective immunity induced by natural infection and immunization with whole inactivated organisms and is relevant to rational chlamydia vaccine design strategies.

Coming of age: carbohydrates and immunity

Adaptive immune responses have long been considered the "territory" of antigenic proteins, whereas carbohydrates are characterized as T-cell-independent antigens that are not typically recognized by the complete adaptive machinery. The current modus operandi when searching for dominant epitopes is the use of synthetic peptides designed from the primary structure of interesting target proteins; however, there is growing evidence that sugars can also play a critical role in immune recognition. Findings reported in this issue of the European Journal of Immunology begin to shed light on the differences in protein glycosylation that can occur in association with disorders like rheumatoid arthritis and the effect these changes have on collagen recognition by the immune system. Other recent studies have shown that immunodominant glycopeptide "remnant" epitopes as well as glycosylation changes on self-proteins can generate autoimmunity. Finally, some types of carbohydrates are now known to be processed and presented to T cells by class II MHC. Taken together, these advances illustrate a clear importance for carbohydrate recognition in foreign and self antigens by the adaptive immune system. With the common presence of carbohydrate molecules on eukaryotic, prokaryotic, and viral surfaces, the impact of carbohydrates on adaptive immunity is now indisputable.

Modelling of multiple sclerosis: lessons learned in a non-human primate

The many, highly specific, biological therapies for immune-based diseases create a need for valid preclinical animal models. The wide immunological gap between human beings and laboratory mouse or rat models makes many disease models in these species invalid. In this review, we report a non-human-primate model of chronic multiple sclerosis (MS)-experimental autoimmune encephalitis (EAE) in the common marmoset (Callithrix jacchus)-that can help bridge this wide gap. The genetic and immunological similarity of marmosets and human beings and the clinical and neuropathological similarity of the EAE model to MS provide a unique experimental platform for research into basic immunopathogenetic mechanisms and for the development of more effective treatments for MS.

Andrographolide interferes with T cell activation and reduces experimental autoimmune encephalomyelitis in the mouse

Andrographolide is a bicyclic diterpenoid lactone derived from extracts of Andrographis paniculata, a plant indigenous to South Asian countries that shows anti-inflammatory properties. The molecular and cellular bases for this immunomodulatory capacity remain unknown. Here, we show that andrographolide is able to down-modulate both humoral and cellular adaptive immune responses. In vitro, this molecule was able to interfere with T cell proliferation and cytokine release in response to allogenic stimulation. These results were consistent with the observation that T cell activation by dendritic cells (DCs) was completely abolished by exposing DCs to andrographolide during antigen pulse. This molecule was able to interfere with maturation of DCs and with their ability to present antigens to T cells. Furthermore, in vivo immune responses such as antibody response to a thymus-dependent antigen and delayed-type hypersensitivity were drastically diminished in mice by andrographolide treatment. Finally, the ability of andrographolide to inhibit T cell activation was applied to interfere with the onset of experimental autoimmune encephalomyelitis (EAE), an inflammatory demyelinating disease of the central nervous system that is primarily mediated by CD4(+) T cells and serves as an animal model for human multiple sclerosis. Treatment with andrographolide was able to significantly reduce EAE symptoms in mice by inhibiting T cell and antibody responses directed to myelin antigens. Our data suggest that andrographolide is able to efficiently block T cell activation in vitro, as well as in vivo, a feature that could be useful for interfering with detrimental T cell responses.