Co-stimulation in T cell responses

Profiling of Tumor-Infiltrating Immune Cells and Their Impact on Survival in Glioblastoma Patients Undergoing Immunotherapy with Dendritic Cells

Glioblastomas (GBM) are the most common primary malignant brain tumors, comprising 2% of all cancers in adults. Their location and cellular and molecular heterogeneity, along with their highly infiltrative nature, make their treatment challenging. Recently, our research group reported promising results from a prospective phase II clinical trial involving allogeneic vaccination with dendritic cells (DCs). To date, six out of the thirty-seven reported cases remain alive without tumor recurrence. In this study, we focused on the characterization of infiltrating immune cells observed at the time of surgical resection. An analytical model employing a neural network-based predictive algorithm was used to ascertain the potential prognostic implications of immunological variables on patients' overall survival. Counterintuitively, immune phenotyping of tumor-associated macrophages (TAMs) has revealed the extracellular marker PD-L1 to be a positive predictor of overall survival. In contrast, the elevated expression of CD86 within this cellular subset emerged as a negative prognostic indicator. Fundamentally, the neural network algorithm outlined here allows a prediction of the responsiveness of patients undergoing dendritic cell vaccination in terms of overall survival based on clinical parameters and the profile of infiltrated TAMs observed at the time of tumor excision.

Analysis of Immune Resistance Mechanisms in TNBC: Dual Effects Inside and Outside the Tumor

Triple-negative breast cancer (TNBC) is a unique subtype of breast cancer characterized by the lack of expression of the estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. TNBC exhibits a high degree of aggressiveness, metastatic potential, and a poor prognosis. Despite the limited success of conventional treatments, immune checkpoint inhibitors (ICIs) have emerged as promising therapeutics for TNBC. Therefore, understanding the mechanisms underlying innate and acquired resistance to ICIs in TNBC is essential. Numerous studies suggest that intrinsic and extrinsic factors significantly contribute to the development of ICI resistance in TNBC. Intrinsic resistance may result from alterations in tumor-intrinsic signaling pathways, such as dysregulation of interferon (IFN) signaling or other signaling pathways. In contrast, extratumoral mechanisms may develop due to alterations in the tumor microenvironment, changes in T cell-related factors or adaptations within the immune system itself. In this paper, we endeavor to elucidate the underlying mechanisms of immune resistance by systematically examining immune mechanisms, the present state of immunotherapy, and the processes of immune resistance. Nonetheless, enhancing our understanding of the mechanisms underlying intratumoral and extratumoral resistance to ICIs in TNBC is crucial for optimizing patient outcomes in this challenging disease. Persistent efforts to identify novel targets for combination therapies, biomarkers that can predict the response to immunotherapy, and resistance mechanisms will be instrumental in achieving this objective.

Cancer Nano-Immunotherapy: The Novel and Promising Weapon to Fight Cancer

Cancer is a complex disease that, despite advances in treatment and the greater understanding of the tumor biology until today, continues to be a prevalent and lethal disease. Chemotherapy, radiotherapy, and surgery are the conventional treatments, which have increased the survival for cancer patients. However, the complexity of this disease together with the persistent problems due to tumor progression and recurrence, drug resistance, or side effects of therapy make it necessary to explore new strategies that address the challenges to obtain a positive response. One important point is that tumor cells can interact with the microenvironment, promoting proliferation, dissemination, and immune evasion. Therefore, immunotherapy has emerged as a novel therapy based on the modulation of the immune system for combating cancer, as reflected in the promising results both in preclinical studies and clinical trials obtained. In order to enhance the immune response, the combination of immunotherapy with nanoparticles has been conducted, improving the access of immune cells to the tumor, antigen presentation, as well as the induction of persistent immune responses. Therefore, nanomedicine holds an enormous potential to enhance the efficacy of cancer immunotherapy. Here, we review the most recent advances in specific molecular and cellular immunotherapy and in nano-immunotherapy against cancer in the light of the latest published preclinical studies and clinical trials.

CD80-Fc fusion protein as a potential cancer immunotherapy strategy

The activation of T lymphocytes is a crucial component of the immune response, and the presence of CD80, a membrane antigen, is necessary for T-cell activation. CD80 is usually expressed on antigen-presenting cells (APCs), which can interact with cluster of differentiation 28 (CD28) or programmed cell death ligand 1 (PD-L1) to promote T-cell proliferation, differentiation and function by activating costimulatory signal or blocking inhibitory signal. Simultaneously, CD80 on the APCs also interacts with cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) on the surface of T cells to suppress the response of specific effector T cells, particularly in the context of persistent antigenic stimulation. Due to the pivotal role of CD80 in the immune response, the CD80-Fc fusion protein has emerged as a promising approach for cancer immunotherapy. This review primarily focused on the crucial role of CD80 in the cancer immunotherapy. We also reviewed the current advancements in the research of CD80-Fc fusion proteins. Finally, we deliberated on the challenges encountered by CD80-Fc fusion proteins and proposed the potential strategies that could yield the benefits for patients.

Preconditioning with immunogenic cell death-inducing treatments for subsequent immunotherapy

Since the dawn of anticancer immunotherapy, the clinical use of immune checkpoint inhibitors (ICI) has increased exponentially. Monoclonal antibodies targeting CTLA-4 and the PD-1/PD-L1 interaction were first introduced for the treatment of patients with unresectable melanoma. In melanoma, ICI lead to durable regression in a significant number of patients and have thus been clinically approved as a first-line treatment of advanced disease. Over the past years an increasing number of regulatory approvals have been granted for the use of ICI in patients affected by a large range of distinct carcinomas. In retrospect surprisingly, it has been discovered that particularly successful chemotherapeutic treatments are able to trigger anticancer immune responses because they induce immunogenic cell death (ICD), hence killing cancer cells in a way that they elicit an immune response against tumor-associated antigens. Logically, preclinical studies as well as clinical trials are currently exploring the possibility to combine ICD inducers with ICI to obtain optimal therapeutic effects. Here, we provide a broad overview of current strategies for the implementation of combinatorial approaches involving ICD induction followed by ICI in anticancer therapy.

Immune Checkpoint Inhibitor Associated Myocarditis and Cardiomyopathy: A Translational Review

Immune checkpoint inhibitors (ICIs) have revolutionized oncology and transformed the treatment of various malignancies. By unleashing the natural immunological brake of the immune system, ICIs were initially considered an effective, gentle therapy with few side effects. However, accumulated clinical knowledge reveals that ICIs are associated with inflammation and tissue damage in multiple organs, leading to immune-related adverse effects (irAEs). Most irAEs involve the skin and gastrointestinal tract; however, cardiovascular involvement is associated with very high mortality rates, and its underlying pathomechanisms are poorly understood. Ranging from acute myocarditis to chronic cardiomyopathies, ICI-induced cardiotoxicity can present in various forms and entities. Revealing the inciting factors, understanding the pathogenesis, and identifying effective treatment strategies are needed to improve the care of tumor patients and our understanding of the immune and cardiovascular systems.

Development and characterization of a novel human CD137 agonistic antibody with anti-tumor activity and a good safety profile in non-human primates

CD137 (4-1BB, TNFRSF9), an inducible T-cell costimulatory receptor, is expressed on activated T cells, activated NK cells, Treg cells, and several innate immune cells, including DCs, monocytes, neutrophils, mast cells, and eosinophils. In animal models and clinical trials, anti-CD137 agonistic monoclonal antibodies have shown anti-tumor potential, but balancing the efficacy and toxicity of anti-CD137 agonistic monoclonal antibodies is a considerable hindrance for clinical applications. Here, we describe a novel fully human CD137 agonistic antibody (PE0116) generated from immunized harbor H2L2 human transgenic mice. PE0116 is a ligand blocker, which is also the case for Utomilumab (one of the leading CD137 agonistic drugs); PE0116 partially overlaps with Urelumab's recognized epitope. In vitro, PE0116 activates NF-κB signaling, significantly promotes T-cell proliferation, and increases cytokine secretion in the presence of cross-linking. Importantly, PE0116 possesses robust anti-tumor activity in the MC38 tumor model. In vivo, PE0116 exhibits a good safety profile and has typical pharmacokinetic characteristics of an IgG antibody in preclinical studies of non-human primates. In summary, PE0116 is a promising anti-CD137 antibody with a good safety profile in preclinical studies.

Bifidobacterium animalis KV9 and Lactobacillus vaginalis FN3 alleviated β-lactoglobulin-induced allergy by modulating dendritic cells in mice

Food allergy is a serious public health problem because of its high incidence and risk. Probiotics can induce immune regulation in patients with allergic diseases, but its mechanism is not fully clear. In this paper, β-lactoglobulin (β-LG)-sensitized mice were used as models to explore the mechanism of Bifidobacterium animalis KV9 (KV9) and Lactobacillus vaginalis FN3 (FN3) on reducing allergic reactions and regulating immune cell function. The results showed that oral administration of KV9 and FN3 significantly reduced the scores of allergic symptoms, hypothermia symptoms, and serum levels of β-LG-specific immunoglobulins E (β-LG-sIgE), histamine, and mast cell protease in allergic mice. Flow cytometry analysis of intestinal dendritic cells (DCs) showed that the proportion of CD11c+major histocompatibility complex (MHC)-II+DCs, CD11c+CD80+DCs, and CD11c+ CD86+DCs increased after KV9 and FN3 intervention, indicating that the strains induced immature DCs and decreased the antigen-presenting capacity of DCs. Meanwhile, the toll-like receptor 4 (TLR4)-NF-κB signaling pathway was activated in DCs. The secretion of interleukin-12 (IL-12) was significantly increased, while interleukin-4 (IL-4) was decreased by DCs after KV9 and FN3 intervention, indicating that DCs have the potential to promote T-cell differentiation into T helper type 1 (Th1) cells. Furthermore, the proportion of CD3+CD8−IFN-γ+ T cells in the spleen increased, while CD3+CD8−IL-4+T cells decreased after oral administration of KV9 and FN3, correcting the T helper type 2 (Th2)-skewed immune responses. These results indicate that KV9 and FN3 reduce β-LG-induced allergic symptoms in mice, and suggest that the two potential probiotics might be used as an alternative therapeutic agent for mitigating food allergy.

Tumor immunotherapies by immune checkpoint inhibitors (ICIs); the pros and cons

The main breakthrough in tumor immunotherapy was the discovery of immune checkpoint (IC) proteins, which act as a potent suppressor of the immune system by a myriad of mechanisms. After that, scientists focused on the immune checkpoint molecules mainly. Thereby, much effort was spent to progress novel strategies for suppressing these inhibitory axes, resulting in the evolution of immune checkpoint inhibitors (ICIs). Then, ICIs have become a promising approach and shaped a paradigm shift in tumor immunotherapies. CTLA-4 plays an influential role in attenuation of the induction of naïve and memory T cells by engagement with its responding ligands like B7-1 (CD80) and B7-2 (CD86). Besides, PD-1 is predominantly implicated in adjusting T cell function in peripheral tissues through its interaction with programmed death-ligand 1 (PD-L1) and PD-L2. Given their suppressive effects on anti-tumor immunity, it has firmly been documented that ICIs based therapies can be practical and rational therapeutic approaches to treat cancer patients. Nonetheless, tumor inherent or acquired resistance to ICI and some treatment-related toxicities restrict their application in the clinic. The current review will deliver a comprehensive overview of the ICI application to treat human tumors alone or in combination with other modalities to support more desired outcomes and lower toxicities in cancer patients. Video Abstract.

Combination therapy with immune checkpoint inhibitors (ICIs); a new frontier

Recently, immune checkpoint inhibitors (ICIs) therapy has become a promising therapeutic strategy with encouraging therapeutic outcomes due to their durable anti-tumor effects. Though, tumor inherent or acquired resistance to ICIs accompanied with treatment-related toxicities hamper their clinical utility. Overall, about 60-70% of patients (e.g., melanoma and lung cancer) who received ICIs show no objective response to intervention. The resistance to ICIs mainly caused by alterations in the tumor microenvironment (TME), which in turn, supports angiogenesis and also blocks immune cell antitumor activities, facilitating tumor cells' evasion from host immunosurveillance. Thereby, it has been supposed and also validated that combination therapy with ICIs and other therapeutic means, ranging from chemoradiotherapy to targeted therapies as well as cancer vaccines, can capably compromise tumor resistance to immune checkpoint blocked therapy. Herein, we have focused on the therapeutic benefits of ICIs as a groundbreaking approach in the context of tumor immunotherapy and also deliver an overview concerning the therapeutic influences of the addition of ICIs to other modalities to circumvent tumor resistance to ICIs.

Cancer immunotherapy: Challenges and limitations

Although cancer immunotherapy has taken center stage in mainstream oncology inducing complete and long-lasting tumor regression, only a subset of patients receiving treatment respond and others relapse after an initial response. Different tumor types respond differently, and even in cancer types that respond (hot tumors), we still observe tumors that are unresponsive (cold tumors), suggesting the presence of resistance. Hence, the development of intrinsic or acquired resistance is a big challenge for the cancer immunotherapy field. Resistance to immunotherapy, including checkpoint inhibitors, CAR-T cell therapy, oncolytic viruses, and recombinant cytokines arises due to cancer cells employing several mechanisms to evade immunosurveillance.

The "Magic Bullet" Is Here? Cell-Based Immunotherapies for Hematological Malignancies in the Twilight of the Chemotherapy Era

Despite the introduction of a plethora of different anti-neoplastic approaches including standard chemotherapy, molecularly targeted small-molecule inhibitors, monoclonal antibodies, and finally hematopoietic stem cell transplantation (HSCT), there is still a need for novel therapeutic options with the potential to cure hematological malignancies. Although nowadays HSCT already offers a curative effect, its implementation is largely limited by the age and frailty of the patient. Moreover, its efficacy in combating the malignancy with graft-versus-tumor effect frequently coexists with undesirable graft-versus-host disease (GvHD). Therefore, it seems that cell-based adoptive immunotherapies may constitute optimal strategies to be successfully incorporated into the standard therapeutic protocols. Thus, modern cell-based immunotherapy may finally represent the long-awaited "magic bullet" against cancer. However, enhancing the safety and efficacy of this treatment regimen still presents many challenges. In this review, we summarize the up-to-date state of the art concerning the use of CAR-T cells and NK-cell-based immunotherapies in hemato-oncology, identify possible obstacles, and delineate further perspectives.

T cell co-stimulation and co-inhibition in cardiovascular disease: a double-edged sword

The role of inflammation in cardiovascular disease (CVD) is now widely accepted. Immune cells, including T cells, are influenced by inflammatory signals and contribute to the onset and progression of CVD. T cell activation is modulated by T cell co-stimulation and co-inhibition pathways. Immune checkpoint inhibitors (ICIs) targeting T cell inhibition pathways have revolutionized cancer treatment and improved survival in patients with cancer. However, ICIs might induce cardiovascular toxicity via T cell re-invigoration. With the rising use of ICIs for cancer treatment, a timely overview of the role of T cell co-stimulation and inhibition molecules in CVD is desirable. In this Review, the importance of these molecules in the pathogenesis of CVD is highlighted in preclinical studies on models of CVD such as vein graft disease, myocarditis, graft arterial disease, post-ischaemic neovascularization and atherosclerosis. This Review also discusses the therapeutic potential of targeting T cell co-stimulation and inhibition pathways to treat CVD, as well as the possible cardiovascular benefits and adverse events after treatment. Finally, the Review emphasizes that patients with cancer who are treated with ICIs should be monitored for CVD given the reported association between the use of ICIs and the risk of cardiovascular toxicity.

Molecular and Cellular Functions of CTLA-4

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is an inhibitory receptor belonging to the CD28 immunoglobulin subfamily, expressed primarily by T-cells. Its ligands, CD80 and CD86, are typically found on the surface of antigen-presenting cells and can either bind CD28 or CTLA-4, resulting in a costimulatory or a co-inhibitory response, respectively. Because of its dampening effect, CTLA-4 is a crucial regulator of T-cell homeostasis and self-tolerance. The mechanisms by which CTLA-4 exerts its inhibitory function can be categorized as either cell-intrinsic (affects the CTLA-4 expressing T-cell) or cell-extrinsic (affects secondary cells). Research from the last decade has shown that CTLA-4 mainly acts in a cell-extrinsic manner via its competition with CD28, CTLA-4-mediated trans-endocytosis of CD80 and CD86, and its direct tolerogenic effects on the interacting cell. Nonetheless, intrinsic CTLA-4 signaling has been implicated in T-cell motility and the regulation of CTLA-4 its subcellular localization amongst others. CTLA-4 is well recognized as a key immune checkpoint and has gained significant momentum as a therapeutic target in the field of autoimmunity and cancer. In this chapter, we describe the role of costimulation in immune response induction as well as the main mechanisms by which CTLA-4 can inhibit this process.

Metabolism and Autoimmune Responses: The microRNA Connection

Distinct metabolic pathways are known to regulate growth, differentiation, survival, and activation of immune cells by providing energy and specific biosynthetic precursors. Compelling experimental evidence demonstrates that effector T cell functions are coupled with profound changes in cellular metabolism. Importantly, the effector T cell-dependent “anti-self” response characterizing the autoimmune diseases is accompanied by significant metabolic alterations. MicroRNAs (miRNAs), evolutionary conserved small non-coding RNA molecules that affect gene expression by binding to target messenger RNAs, are now known to regulate multiple functions of effector T cells, including the strength of their activation, thus contributing to immune homeostasis. In this review, we will examine the most recent studies that describe miRNA direct involvement in the metabolic reprogramming that marks effector T cell functions. In particular, we will focus on the work showing a connection between miRNA regulatory function and the molecular network dysregulation that leads to metabolic pathway derangement in autoimmunity. Finally, we will also speculate on the possibility that the interplay between miRNAs and metabolism in T cells may help identify novel miRNA-based therapeutic strategies to treat effector T cell immunometabolic alterations in pathological conditions such as autoimmunity and chronic inflammation.

Recent perspective on CAR and Fcγ-CR T cell immunotherapy for cancers: Preclinical evidence versus clinical outcomes

The chimeric antigen receptor T cell (CAR-T cell) immunotherapy currently represents a hot research trend and it is expected to revolutionize the field of cancer therapy. Promising outcomes have been achieved using CAR-T cell therapy for haematological malignancies. Despite encouraging results, several challenges still pose eminent hurdles before being fully recognized. Directing CAR-T cells to target a single tumour associated antigen (TAA) as the case in haematological malignancies might be much simpler than targeting the extensive inhibitory microenvironments associated with solid tumours. This review focuses on the basic principles involved in development of CAR-T cells, emphasizing the differences between humoral IgG, T-cell receptors, CAR and Fcγ-CR constructs. It also highlights the complex inhibitory network that is usually associated with solid tumours, and tackles recent advances in the clinical studies that have provided great hope for the future use of CAR-T cell immunotherapy. While current Fcγ-CR T cell immunotherapy is in pre-clinical stage, is expected to provide a sound therapeutic approach to add to existing classical chemo- and radio-therapeutic modalities.

Association between Increased Inducible Costimulator/Inducible Costimulator Ligand Expression with Bone Destruction in Apical Periodontitis

INTRODUCTION

The aim was to assess the association of inducible costimulator (ICOS) and ICOS ligand with bone destruction in apical periodontitis (AP).

METHODS

Specimens from patients presenting with AP were obtained during apicoectomy and subjected to histopathologic analysis and molecular assessment of ICOS/ICOS ligand. In addition, the experimental AP was induced by exposing the pulp of first mandibular molars of rats. Histologic and radiographic examinations were performed to validate the periapical lesions. The immunolocalization and messenger RNA expression of ICOS/ICOS ligand were evaluated by immunofluorescence staining and quantitative real-time polymerase chain reaction. The osteoclastic activities in periapical lesions, including the lesion size and the expression of tartrate-resistant acid phosphatase and the receptor activator of nuclear factor kappa B ligand, were recorded and followed by correlation analysis with ICOS/ICOS ligand expression.

RESULTS

In excisional specimens from AP patients, a significantly increased expression of ICOS/ICOS ligand was found compared with the healthy control. In the experimental AP samples, the expression of ICOS/ICOS ligand, tartrate-resistant acid phosphatase, and receptor activator of nuclear factor kappa B ligand was significantly elevated in inflamed periapical tissues (AP group) when compared with the healthy control. The number of ICOS⁺/ICOS ligand⁺ cells was highly correlated with the periapical lesion size (r = 0.892, P < .01 and r = 0.930, P < .01, respectively).

CONCLUSIONS

The increased expression of ICOS/ICOS ligand in periapical lesions was associated with the inflammatory infiltration and alveolar bone destruction of AP.

Isolation of B-cells using Miltenyi MACS bead isolation kits

This article describes the procedures used to isolate pure B-cell populations from whole blood using various Miltenyi magnetic-activated cell sorting (MACS) bead Isolation kits. Such populations are vital for studies investigating the functional capacity of B-cells, as the presence of other cell types may have indirect effects on B-cell function through cell-cell interactions or by secretion of several soluble molecules. B-cells can be isolated by two main approaches: 1) Negative selection—in which B-cells remain “untouched” in their native state; this is advantageous as it is likely that B-cells remain functionally unaltered by this process. 2) Positive selection–in which B-cells are labelled and actively removed from the sample. We used three Negative B-cell isolation kits as well as the Positive B-cell isolation kit from Miltenyi and compared the purity of each of the resulting B-cells fractions. Contamination of isolated B-cell fractions with platelets was the conclusive finding for all of the isolation techniques tested. These results illustrate the inefficiency of current available MACS B-cell isolation kits to produce pure B-cell populations, from which concrete findings can be made. As such we suggest cell sorting as the preferred method for isolating pure B-cells to be used for downstream functional assays.

Structures of Immune Checkpoints: An Overview on the CD28-B7 Family

The co-stimulation and co-inhibition signal pathways, immune checkpoints, are among the central mechanisms to regulate the T-cell immunity. Optimal signals involve intricate interactions of numerous ligands and receptors. Manipulation of these signals offers great clinical opportunities and has revolutionized the cancer treatment therapies. The 2018 Nobel Prize in Physiology or Medicine was awarded to James P. Allison and Tasuku Honjo in recognition of their discovery of cancer immunotherapy by inhibition of immune checkpoint molecules. Despite the landmark discovery in cancer immunotherapy, the efforts to harness immunity against cancer are also restricted by the limited knowledge on the co-stimulation and co-inhibition signaling networks. Understanding the structures of these molecules, in particular, tackling the interaction paradigms from the structural perspective, help to provide more accurate insights into the signaling mechanisms, which may further facilitate the development of novel biologics and improve the efficacy of the existing biologics against these targets. Here we review our current understanding on the structures of these co-stimulatory and co-inhibitory molecules. Specifically, we focus on the structural basis of several checkpoint molecules among the CD28-B7 family and discuss the therapeutic drugs against these targets for the treatment of human cancers, autoimmune disorders, and transplantation.

Immunotherapies for malignant glioma

Glioblastoma multiforme (GBM) is a highly malignant primary brain cancer with a dreadful overall survival and for which treatment options are limited. Recent breakthroughs in novel immune-related treatment strategies for cancer have spurred interests in usurping the power of the patient's immune system to recognize and eliminate GBM. Here, we discuss the unique properties of GBM's tumor microenvironment, the effects of GBM standard on care therapy on tumor-associated immune cells, and review several approaches aimed at therapeutically targeting the immune system for GBM treatment. We believe that a comprehensive understanding of the intricate micro-environmental landscape of GBM will abound into the development of novel immunotherapy strategies for GBM patients.

Adoptive T-Cell Therapy for Solid Tumors

Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of immunotherapy wherein autologous T cells are genetically modified to express chimeric receptors encoding an antigen-specific single-chain variable fragment and various costimulatory molecules. Upon administration, these modified T cells traffic to, and recognize, cancer cells in an HLA-independent manner. CAR T-cell therapy has shown remarkable success in the treatment of CD-19-expressing B-cell acute lymphocytic leukemia. However, clinical gains to the same magnitude have not been reported in solid tumors. Several known obstacles to CAR T-cell therapy for solid tumors include target antigen identification, effective trafficking to the tumor, robust activation, proliferation, and in vivo cytotoxicity. Beyond these T-cell intrinsic properties, a complex and dynamic immunosuppressive tumor microenvironment in solid tumors hinders T-cell efficacy. Notable advancements in CAR design to include multiple costimulatory molecules, ligands, and soluble cytokines have shown promise in preclinical models, and some of these are currently in early-phase clinical trials. In this review, we discuss selected solid tumor malignancies and relevant preclinical data and highlight clinical trial results that are available. Furthermore, we outline some obstacles to CAR T-cell therapy for each tumor and propose strategies to overcome some of these limitations.

Adoptive T-Cell Therapy for Solid Tumors

Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of immunotherapy wherein autologous T cells are genetically modified to express chimeric receptors encoding an antigen-specific single-chain variable fragment and various costimulatory molecules. Upon administration, these modified T cells traffic to, and recognize, cancer cells in an HLA-independent manner. CAR T-cell therapy has shown remarkable success in the treatment of CD-19-expressing B-cell acute lymphocytic leukemia. However, clinical gains to the same magnitude have not been reported in solid tumors. Several known obstacles to CAR T-cell therapy for solid tumors include target antigen identification, effective trafficking to the tumor, robust activation, proliferation, and in vivo cytotoxicity. Beyond these T-cell intrinsic properties, a complex and dynamic immunosuppressive tumor microenvironment in solid tumors hinders T-cell efficacy. Notable advancements in CAR design to include multiple costimulatory molecules, ligands, and soluble cytokines have shown promise in preclinical models, and some of these are currently in early-phase clinical trials. In this review, we discuss selected solid tumor malignancies and relevant preclinical data and highlight clinical trial results that are available. Furthermore, we outline some obstacles to CAR T-cell therapy for each tumor and propose strategies to overcome some of these limitations.

Inducible T-cell costimulator (ICOS) and CD28 polymorphisms possibly play a role in the pathogenesis of chronic autoreactive urticaria

BACKGROUND

Clinical experience emphasizes the coexistence of chronic spontaneous urticaria (CSU) and autoimmune disturbances. In chromosome 2q33-34, there is a cluster of homologous genes that are considered promising candidate genes for susceptibility to autoimmune diseases.

AIM

To examine the possible role of polymorphisms in the genes for CD28 and inducible T-cell costimulator (ICOS) in the background of CSU.

METHODS

In total, 149 patients with CSU with positive autologous serum skin test were enrolled in the study. The healthy control (HC) group consisted of 100 healthy volunteers. In all subjects, the CD28 rs2140148 and rs3116496 and the ICOS rs6726035 polymorphisms were analysed. Disease severity was assessed by means of Urticaria Activity Score.

RESULTS

We found a statistically significantly lower prevalence of the ICOS rs6726035 TT genotype among patients with CSU compared with HCs. Furthermore, the haplotype rs2140148A, rs3116496T and rs6726035C presented a possible association with CSU. We did not find any association between the examined polymorphisms and either urticaria severity or age of disease onset.

CONCLUSIONS

Our results underline the role of autoimmune components in the pathogenesis of chronic autoreactive urticaria, and indicate it as a potentially genetically related disorder.

CD28 days later: Resurrecting costimulation for CD8(+) memory T cells

Rapid activation and proliferative expansion of specific CD8(+) memory T (CD8(+) TM ) cells upon antigen re-encounter is a critical component of the adaptive immune response that confers enhanced immune protection. In this context, however, the requirements for costimulation in general, and CD28 signaling in particular, remain incompletely defined. In the current issue of the European Journal of Immunology, Fröhlich et al. [Eur. J. Immunol. 2016. 46: 1644-1655] provide definitive evidence that optimal elaboration of CD8(+) TM -cell recall responses is indeed contingent on CD28 expressed by these cells. Here, we discuss the "CD28 costimulation paradigm" in its historical context and highlight some of the unresolved complexities pertaining to CD28-dependent interactions that shape CD8(+) T-cell phenotypes, functionalities, and recall reactivity.

Peptide-Conjugated Nanoparticles Reduce Positive Co-stimulatory Expression and T Cell Activity to Induce Tolerance

Targeted approaches to treat autoimmune diseases would improve upon current therapies that broadly suppress the immune system and lead to detrimental side effects. Antigen-specific tolerance was induced using poly(lactide-co-glycolide) nanoparticles conjugated with disease-relevant antigen to treat a model of multiple sclerosis. Increasing the nanoparticle dose and amount of conjugated antigen both resulted in more durable immune tolerance. To identify active tolerance mechanisms, we investigated downstream cellular and molecular events following nanoparticle internalization by antigen-presenting cells. The initial cell response to nanoparticles indicated suppression of inflammatory signaling pathways. Direct and functional measurement of surface MHC-restricted antigen showed positive correlation with both increasing particle dose from 1 to 100 μg/mL and increasing peptide conjugation by 2-fold. Co-stimulatory analysis of cells expressing MHC-restricted antigen revealed most significant decreases in positive co-stimulatory molecules (CD86, CD80, and CD40) following high doses of nanoparticles with higher peptide conjugation, whereas expression of a negative co-stimulatory molecule (PD-L1) remained high. T cells isolated from mice immunized against myelin proteolipid protein (PLP139-151) were co-cultured with antigen-presenting cells administered PLP139-151-conjugated nanoparticles, which resulted in reduced T cell proliferation, increased T cell apoptosis, and a stronger anti-inflammatory response. These findings indicate several potential mechanisms used by peptide-conjugated nanoparticles to induce antigen-specific tolerance.

Gene therapy: advances, challenges and perspectives

The ability to make site-specific modifications to the human genome has been an objective in medicine since the recognition of the gene as the basic unit of heredity. Thus, gene therapy is understood as the ability of genetic improvement through the correction of altered (mutated) genes or site-specific modifications that target therapeutic treatment. This therapy became possible through the advances of genetics and bioengineering that enabled manipulating vectors for delivery of extrachromosomal material to target cells. One of the main focuses of this technique is the optimization of delivery vehicles (vectors) that are mostly plasmids, nanostructured or viruses. The viruses are more often investigated due to their excellence of invading cells and inserting their genetic material. However, there is great concern regarding exacerbated immune responses and genome manipulation, especially in germ line cells. In vivo studies in in somatic cell showed satisfactory results with approved protocols in clinical trials. These trials have been conducted in the United States, Europe, Australia and China. Recent biotechnological advances, such as induced pluripotent stem cells in patients with liver diseases, chimeric antigen receptor T-cell immunotherapy, and genomic editing by CRISPR/Cas9, are addressed in this review.

CAR T-Cell Therapy: Progress and Prospects

Lentivirus-mediated transduction of autologous T cells with a chimeric antigen receptor (CAR) to confer a desired epitope specificity as a targeted immunotherapy for cancer has been among the first human gene therapy techniques to demonstrate widespread therapeutic efficacy. Other approaches to using gene therapy to enhance antitumor immunity have been less specific and less effective. These have included amplification, marking, and cytokine transduction of tumor infiltrating lymphocytes, recombinant virus-based expression of tumor antigens as a tumor vaccine, and transduction of antigen-presenting cells with tumor antigens. Unlike any of those methods, the engineering of CAR T cells combine specific monoclonal antibody gene sequences to confer epitope specificity and other T-cell receptor and activation domains to create a self-contained single vector approach to produce a very specific antitumor response, as is seen with CD19-directed CAR T cells used to treat CD19-expressing B-cell malignancies. Recent success with these therapies is the culmination of a long step-wise iterative process of improvement in the design of CAR vectors. This review aims to summarize this long series of advances in the development of effective CAR vector since their initial development in the 1990s, and to describe emerging approaches to design that promise to enhance and widen the human gene therapy relevance of CAR T-cell therapy in the future.

Immunometabolic Regulations Mediated by Coinhibitory Receptors and Their Impact on T Cell Immune Responses

Host immunity provides wide spectrum protection that serves to eradicate pathogens and cancer cells, while maintaining self-tolerance and immunological homeostasis. Ligation of the T cell receptor (TCR) by antigen activates signaling pathways that coordinately induce aerobic glycolysis, mitochondrial activity, anabolic metabolism, and T effector cell differentiation. Activation of PI3K, Akt, and mTOR triggers the switch to anabolic metabolism by inducing transcription factors such as Myc and HIF1, and the glucose transporter Glut1, which is pivotal for the increase of glucose uptake after T cell activation. Activation of MAPK signaling is required for glucose and glutamine utilization, whereas activation of AMPK is critical for energy balance and metabolic fitness of T effector and memory cells. Coinhibitory receptors target TCR-proximal signaling and generation of second messengers. Imbalanced activation of such signaling pathways leads to diminished rates of aerobic glycolysis and impaired mitochondrial function resulting in defective anabolic metabolism and altered T cell differentiation. The coinhibitory receptors mediate distinct and synergistic effects on the activation of signaling pathways thereby modifying metabolic programs of activated T cells and resulting in altered immune functions. Understanding and therapeutic targeting of metabolic programs impacted by coinhibitory receptors might have significant clinical implications for the treatment of chronic infections, cancer, and autoimmune diseases.

Armored CAR T-cells: utilizing cytokines and pro-inflammatory ligands to enhance CAR T-cell anti-tumour efficacy

Chimaeric antigen receptor (CAR) T-cells are T-cells that have been genetically modified to express an artificial construct consisting of a synthetic T-cell receptor (TCR) targeted to a predetermined antigen expressed on a tumour. Coupling the T-cell receptor to a CD3ζ signalling domain paved the way for first generation CAR T-cells that were efficacious against cluster of differentiation (CD)19-expressing B-cell malignancies. Optimization with additional signalling domains such as CD28 or 4-1BB in addition to CD3ζ provided T-cell activation signal 2 and further improved the efficacy and persistence of these second generation CAR T-cells. Third generation CAR T-cells which utilize two tandem costimulatory domains have also been reported. In this review, we discuss a different approach to optimization of CAR T-cells. Through additional genetic modifications, these resultant armored CAR T-cells are typically modified second generation CAR T-cells that have been further optimized to inducibly or constitutively secrete active cytokines or express ligands that further armor CAR T-cells to improve efficacy and persistence. The choice of the 'armor' agent is based on knowledge of the tumour microenvironment and the roles of other elements of the innate and adaptive immune system. Although there are several variants of armored CAR T-cells under investigation, here we focus on three unique approaches using interleukin-12 (IL-12), CD40L and 4-1BBL. These agents have been shown to further enhance CAR T-cell efficacy and persistence in the face of a hostile tumour microenvironment via different mechanisms.

Status of and prospects for cancer vaccines against hepatocellular carcinoma in clinical trials

Current therapies to treat advanced hepatocellular carcinoma (HCC) are not satisfactory because of the high rate of recurrence after treatment and because of severe complications after surgery. Cancer vaccines have been studied for decades to achieve effective, micro-invasive, long-lasting anti-tumor action. Cancer vaccines are designed to promote tumor-specific immune responses and increase specific cytotoxic CD8-positive T cells. This review summarizes 16 phase I clinical trials of cancer vaccines against HCC that have been conducted over the past 10 years. According to those trials, the Alpha fetoprotein (AFP), Glypican-3 (GPC3), and Multidrug resistance-associated protein 3 (MRP3) vaccines were well tolerated and safe. Some early clinical trials have shown that vaccination resulted in a large number of T cells activated by a specific tumor-associated antigen in the circulation, but clinical outcomes were not satisfactory. This may be because targets for immunosuppressive agents have yet to be clearly determined in HCC. Therapeutic regimens that combine activative agents and suppressive agents may profoundly improve clinical outcomes for patients with HCC in the future.

CAR-modified T-cell therapy for cancer: an updated review

The use of chimeric antigen receptor (CAR)-modified T cells is a promising approach for cancer immunotherapy. These genetically modified receptors contain an antigen-binding moiety, a hinge region, a transmembrane domain, and an intracellular costimulatory domain resulting in T-cell activation subsequent to antigen binding. Optimal tumor removal through CAR-modified T cells requires suitable target antigen selection, co-stimulatory signaling domain, and the ability of CAR T cells to traffic, persist, and retain antitumor function after adoptive transfer. There are several elements which can improve antitumor function of CAR T cells, including signaling, conditioning chemotherapy and irradiation, tumor burden of the disease, T-cell phenotype, and supplementary cytokine usage. This review outlines four generations of CAR. The pre-clinical and clinical studies showed that this technique has a great potential for treatment of solid and hematological malignancies. The main purpose of the current review is to focus on the pre-clinical and clinical developments of CAR-based immunotherapy.

Fusion protein of mutant B7-DC and Fc enhances the antitumor immune effect of GM-CSF-secreting whole-cell vaccine

B7-DC [also known as programmed death ligand 2 (PD-L2)] is a costimulatory molecule expressed predominantly on dendritic cells (DCs) and macrophages. In addition to its coinhibitory receptor, programmed death receptor 1 (PD-1), evidence suggests that B7-DC interacts with an unidentified costimulatory receptor on T cells. B7-DC mutants with selective binding capacity for the costimulatory receptor may be effective in stimulating antitumor immune responses, while avoiding the inhibitory effects of PD-1. In this study, we concomitantly administered a GM-CSF-secreting whole-cell vaccine together with a fusion protein of mutant B7-DC and Fc portion (mB7-DC-Fc), which binds selectively to the costimulatory receptor. This lead to an increased number of tumor antigen-specific cytotoxic T lymphocytes both in the spleen and at the tumor site and complete elimination of established tumors in vivo. In addition, mB7-DC-Fc increased IFN-γ and IL-2 production and decreased IL-4 and IL-10 production in vitro, indicating that mB7-DC-Fc tips the Th1/Th2 balance toward Th1 dominance, which is more favorable for antitumor immunity. Furthermore, mB7-DC-Fc decreased the PD-1(+) proportion of CD8(+) T cells in vitro and tumor-infiltrating CD8(+) T cells in vivo, suggesting that mB7-DC-Fc may maintain tumor-infiltrating CD8(+) T cells in a nonexhausted state. In conclusion, mB7-DC-Fc administration during the T-cell priming phase enhances antitumor effects of vaccine by generating more tumor antigen-specific cytotoxic T lymphocytes and leading to their accumulation at the tumor site. We suggest that this combination approach may be a promising strategy for antitumor immunotherapy.

Curing mice with large tumors by locally delivering combinations of immunomodulatory antibodies

PURPOSE

Immunomodulatory mAbs can treat cancer, but cures are rare except for small tumors. Our objective was to explore whether the therapeutic window increases by combining mAbs with different modes of action and injecting them into tumors.

EXPERIMENTAL DESIGN

Combinations of mAbs to CD137/PD-1/CTLA-4 or CD137/PD-1/CTLA-4/CD19 were administrated intratumorally to mice with syngeneic tumors (B16 and SW1 melanoma, TC1 lung carcinoma), including tumors with a mean surface of approximately 80 mm(2). Survival and tumor growth were assessed. Immunologic responses were evaluated using flow cytometry and qRT-PCR.

RESULTS

More than 50% of tumor-bearing mice had complete regression and long-term survival after tumor injection with mAbs recognizing CD137/PD-1/CTLA-4/CD19 with similar responses in three models. Intratumoral injection was more efficacious than intraperitoneal injection in causing rejection also of untreated tumors in the same mice. The three-mAb combination could also induce regression, but was less efficacious. There were few side effects, and therapy-resistant tumors were not observed. Transplanted tumor cells rapidly caused a Th2 response with increased CD19 cells. Successful therapy shifted this response to the Th1 phenotype with decreased CD19 cells and increased numbers of long-term memory CD8 effector cells and T cells making IFNγ and TNFα.

CONCLUSIONS

Intratumoral injection of mAbs recognizing CD137/PD-1/CTLA-4/CD19 can eradicate established tumors and reverse a Th2 response with tumor-associated CD19 cells to Th1 immunity, whereas a combination lacking anti-CD19 is less effective. There are several human cancers for which a similar approach may provide clinical benefit.

Polyomavirus BK viremia in kidney transplant recipients after desensitization with IVIG and rituximab

BACKGROUND

Desensitization with intravenous immune globulin (IVIG) and rituximab improves transplantation rates. It is unclear if desensitization increases the risk of polyomavirus BK (BKV) viremia. Here, BKV viremia in HLA-sensitized patients after desensitization with IVIG and rituximab was analyzed.

METHODS

Baseline characteristics and outcomes were compared in the desensitized group (N=187) and the non-desensitized group (N=284). Surveillance for BKV viremia was done at 1, 2, 3, 6, 9, and 12 months posttransplant. Univariable and multivariable analyses were performed.

RESULTS

BKV viremia was observed in 20% of the desensitized and 10% of the non-desensitized (P<0.001) groups by 2 years posttransplant. The desensitized group had more lymphocyte depleting induction and more rejection. They also had a greater degree of viremia with more patients having a peak viral load greater than 10,000 copies per milliliter (P<0.001). However, there was no significant difference in BKV-associated nephropathy or graft loss in the two groups. There was an association of BKV viremia with desensitization and lymphocyte induction. Only desensitization remained a significant predictor in the multivariable model with an adjusted HR of 2.13 (95% CI 1.21-3.77, P=0.009).

CONCLUSIONS

Desensitization with IVIG and rituximab is associated with a higher incidence of BKV viremia with high viral copies and was the major predictor of BKV viremia in the multivariable model. More frequent surveillance for BKV viremia and an early, aggressive treatment strategy are essential for preventing high BKV viral loads in this patient population.

CTLA-4 polymorphism in the pathogenesis of chronic spontaneous autoreactive urticaria

BACKGROUND

Autoimmune mechanisms are considered to play a significant role in chronic urticaria pathophysiology. Additionally, clinical experience emphasises the coexistence of chronic urticaria manifestation with thyroid autoimmunity. As the role of CTLA-4 polymorphism in autoimmune thyroid diseases is well proven we speculated on the possible role of this polymorphism in the background of chronic urticaria.

MATERIALS AND METHODS

We included 128 chronic spontaneous autoreactive urticaria patients (87 females and 41 males) and 101 healthy volunteers (71 females and 30 males). In all examined subjects CTLA-4 A49G polymorphism was analysed. Disease severity with Urticaria Activity Score as well as age of disease onset was also studied.

RESULTS

No statistically significant differences in the allele or genotype distribution between urticaria patients and controls were observed. Furthermore, we found no association between CTLA4 polymorphism and urticaria severity as well as the age of disease onset.

CONCLUSIONS

Our data suggest that there is no contribution of CTLA-4 A49G polymorphism to chronic spontaneous autoreactive urticaria susceptibility. We recommend further research on other polymorphisms in chronic urticaria patients to explore in detail the potent role of the genetic background in the pathogenesis of this disorder.

New Approaches in Immunotherapy for the Treatment of Lung Cancer

Despite the several advances in the last few years into treatment of advanced lung cancer, the 5-year survival remains extremely low. New therapeutic strategies are currently under investigation, and immunotherapy seems to offer a promising treatment alternative. In the last decade, therapeutic cancer vaccines in lung cancer have been rather disappointing, mainly due to the lack of efficient predictive biomarkers. A better refinement of the patient population that might respond to treatment might finally lead to a success story. For the first time, the immune checkpoint inhibitors are demonstrating sustained antitumor response and improved survival and they may be the first immunotherapeutics available for patients with lung cancer.

T cell co-stimulatory molecules: a co-conspirator in the pathogenesis of eosinophilic esophagitis?

Eosinophilic esophagitis (EoE) has become a common gastrointestinal disease. It is characterized by severe eosinophil infiltration in the esophagus. EoE is strongly associated with food allergy, asthma, atopic dermatitis, and other allergic diseases. T lymphocytes, especially Th2 cells, play an instrumental role in the development of allergic inflammation. Recent studies have shown that the ligation of co-stimulatory molecules contributes to the activation, differentiation, and proliferation of T cells. In this review, we will discuss the growing evidence of co-stimulatory molecules including OX40, Light, and HVEM in the pathogenesis of Th2-driven EoE. Our goal is to provide the rationale for the development of novel therapy therapies that target co-stimulatory molecules.

Peripheral blood CD40-CD40L expression in human breast cancer

BACKGROUND

Breast cancer is the most common cancer in women. T cell-based immunotherapy for cancer has attracted much attention recently. CD40 and CD40L occupy an important position of specific immune response. In this paper, we want to study the role of co-stimulatory molecules CD40/CD40L and their clinical significance in peripheral blood of patients with breast cancer.

METHODS

Thirty breast cancer patients served as observation group, who were diagnosed as having infiltrating ductal breast cancer histopathologically, and 30 healthy as control group. Flow cytometric analysis was conducted to detect the expression of CD40 and CD40L on B and T lymphocytes in peripheral blood. The relationship between the CD40/CD40L expression levels and pathological grades was analyzed.

RESULTS

The expression levels of CD40/CD40L on B cells and T cells in breast cancer patients were significantly higher than those in the controls (all P < 0.001), and CD40/CD40L levels had a significant positive relationship with pathological grades (all P < 0.001).

CONCLUSIONS

The upregulated levels of co-stimulators CD40/CD40L on B cells and T cells may play an important role in the immune pathogenesis of breast cancer.

Maternal protein deficiency during a gastrointestinal nematode infection alters developmental profile of lymphocyte populations and selected cytokines in neonatal mice

Neonatal immune development begins in pregnancy and continues into lactation and may be affected by maternal diet. We investigated the possibility that maternal protein deficiency (PD) during a chronic gastrointestinal (GI) nematode infection could impair neonatal immune development. Beginning on d 14 of pregnancy, mice were fed protein-sufficient (PS; 24%) or protein-deficient (PD; 6%) isoenergetic diets and were infected weekly with either 0 (sham) or 100 Heligmosomoides bakeri larvae. Pups were killed on d 2, 7, 14, and d 21 and dams on d 20 of lactation. Lymphoid organs were weighed. Cytokine concentration in maternal and pup serum and in milk from pup stomachs and lymphoid cell populations in pup spleen and thymus were determined using luminex and flow cytometry, respectively. GI nematode infection increased Th2 cytokines (IL-4, IL-5, IL-13), IL-2, IL-10, and eotaxin in serum of dams whereas PD reduced IL-4 and IL-13. The lower IL-13 in PD dams was associated with increased fecal egg output and worm burdens. Maternal PD increased vascular endothelial growth factor in pup milk and eotaxin in pup serum. Maternal infection increased eotaxin in pup serum. Evidence of impaired neonatal immune development included reduced lymphoid organ mass in pups associated with both maternal infection and PD and increased percentage of T cells and T:B cell ratio in the spleen associated with maternal PD. Findings suggest that increases in specific proinflammatory cytokines as a result of the combination of infection and dietary PD in dams can impair splenic immune development in offspring.

Chimeric antigen receptors for T cell immunotherapy: current understanding and future directions

BACKGROUND

The genetic engineering of T cells through the introduction of a chimeric antigen receptor (CAR) allows for generation of tumor-targeted T cells. Once expressed by T cells, CARs combine antigen-specificity with T cell activation in a single fusion molecule. Most CARs are comprised of an antigen-binding domain, an extracellular spacer/hinge region, a trans-membrane domain and an intracellular signaling domain resulting in T cell activation after antigen binding.

METHODS

We performed a search of the literature regarding tumor immunotherapy using CAR-modified T cells to provide a concise review of this topic.

RESULTS

This review aims to focus on the elements of CAR design required for successful application of this technology in cancer immunotherapy. Most notably, proper target antigen selection, co-stimulatory signaling, and the ability of CAR-modified T cells to traffic, persist and retain function after adoptive transfer are required for optimal tumor eradication. Furthermore, recent clinical trials have demonstrated tumor burden and chemotherapy conditioning before adoptive transfer as being critically important for this therapy. Future research into counteracting the suppressive tumor microenvironment and the ability to activate an endogenous anti-tumor response by CAR-modified T cells may enhance the therapeutic potential of this treatment.

CONCLUSIONS

In conclusion, CAR-modified T cell therapy is a highly promising treatment for cancer, having already demonstrated both promising preclinical and clinical results. However, further modification and additional clinical trials will need to be conducted to ultimately optimize the anti-tumor efficacy of this approach.

Do MHCII-presented neoantigens drive type 1 diabetes and other autoimmune diseases?

The strong association between particular MHCII alleles and type 1 diabetes is not fully understood. Two ideas that have been considered for many years are that autoimmunity is driven by (1) low-affinity CD4(+) T cells that escape thymic negative selection and respond to certain autoantigen peptides that are particularly well presented by particular MHCII molecules, or (2) CD4(+) T cells responding to neoantigens that are absent in the thymus, but uniquely created in the target tissue in the periphery and presented by particular MHCII alleles. Here we discuss the recent structural data in favor of the second idea. We review studies suggesting that peptide antigens recognized by autoimmune T cells are uniquely proteolytically processed and/or posttranslationally modified in the target tissue, thus allowing these T cells to escape deletion in the thymus during T-cell development. We postulate that an encounter with these tissue-specific neoantigenic peptides presented by the particular susceptible MHCII alleles in the peripheral tissues when accompanied by the appropriate inflammatory milieu activates these T-cell escapees leading to the onset of autoimmune disease.

Increased production of circulating soluble co-stimulatory molecules CTLA-4, CD28 and CD80 in patients with rheumatoid arthritis

Co-stimulatory molecules are key immunoregulatory mediators in regulating T lymphocyte-mediated immune responses and inflammatory reactions. Here we investigated whether there is altered expression and the clinical significance of circulating soluble co-stimulatory molecules in rheumatoid arthritis (RA) patients. Serum concentrations of sCTLA-4, sCD28, sCD80 and sCD86 in 56 RA patients, and 32 sex- and age-matched control subjects were measured by enzyme-linked immunosorbent assay (ELISA). Results showed that serum sCTLA-4, sCD28, and CD80 but not CD86 concentrations in all RA patients were significantly higher than concentrations in healthy control subjects. And there was significant and positive correlation between serum CTLA-4 and sCD28, sCD28 and sCD80, or sCTLA-4 and sCD80 in all RA patients. Serum sCTLA-4 concentration in all RA patients correlated significantly with disease activity score in 28 joints (DAS28). Moreover, immunosuppressant treatment with leflunomide could downregulate the increased levels of sCTLA-4, sCD28, and CD80 in RA patients. Therefore, the elevated production of circulating soluble T-cell co-stimulatory molecules should contribute to the pathogenesis of RA, and serum sCTLA-4 could potentially serve as a new marker of RA disease activity.

Canine leishmaniosis. Modulation of macrophage/lymphocyte interactions by L. infantum

Canine leishmaniosis, caused by Leishmania infantum, is a systemic disease with variable clinical signs and a progressive evolution. This disease is characterized by impaired T cell-mediated immune response, which has been associated with disease chronicity and high mortality. Protective immunity against leishmaniosis is thought to be mediated by T cell and cytokine production. The T cell activation requires a primary signal delivered by the major histocompatibility complex (MHC) molecules present on the surface of antigen presenting cells, and a non-specific signal generated by co-stimulatory molecules. To characterize canine immune responses in the presence of L. infantum parasites or their antigens, in vitro cell cultures of canine macrophages and lymphocytes were established, and the macrophages presenting MHC class II molecules were evaluated as well as the expression of IL-12 and CD80-86 co-stimulatory molecules and nitric oxide production. The results showed for the first time the up-regulation of MHC class II molecules on the surface in canine peripheral blood monocyte-derived macrophages during L. infantum infection in the presence of lymphocytes. In addition, a lack of co-stimulatory expression and a reduced release of nitric oxide were observed, suggesting a loss of T cell function and consequently an inactivation of the macrophage oxidative burst which, in turn, favors the survival of Leishmania. These results constitute a new contribution for the understanding of the interactions between L. infantum and the canine immune system.

Genetic polymorphisms and surface expression of CTLA-4 and PD-1 on T cells of silica-exposed workers

Exposure to silica dust has been examined as a possible risk factor for autoimmune diseases, including scleroderma, rheumatoid arthritis and systemic lupus erythematosus. Since CTLA-4 [CD152] and PD-1 [CD279] are important for the maintenance of peripheral tolerance by regulating T cell responsiveness, we evaluated the expression of these molecules on the surface of CD4 and CD8 T cells, as well as single nucleotide polymorphisms (SNP) in CTLA-4 and PDCD1 genes, of 70 silica-exposed workers and 30 non-exposed, age-, ethnically- and sex-matched controls. Expression of CTLA-4 was significantly (P<0.05) reduced in CD4 T cells of exposed individuals [median=0.1% and interquartile range, IQR 0.0-0.1% (exposed), median=0.20%, IQR 0.0-0.4% (control)]. Also the expression of PD-1 was significantly (P<0.0001) reduced in both CD4 [median=0.9%, IQR 0.4-2.3% (exposed), median=5.7%, IQR 1.4-13.3% (control)] and CD8 T cells [median=0.9%, IQR 0.3-1.9% (exposed), median=5.0%, IQR 3.4-8.9% (control)]. The study of polymorphisms demonstrated a lower frequency of the A allele in the analysis of the PD1.3 SNP in the exposed group, which might be associated with the lower expression of PD-1 on the surface of CD4 T cells. Our findings provide evidence for the association of silica exposure and the maintenance of self-tolerance, i.e., the susceptibility to autoimmune disorders.

Choice of resident costimulatory molecule can influence cell fate in human naïve CD4+ T cell differentiation

With antigen stimulation, naïve CD4+ T cells differentiate to several effector or memory cell populations, and cytokines contribute to differentiation outcome. Several proteins on these cells receive costimulatory signals, but a systematic comparison of their differential effects on naïve T cell differentiation has not been conducted. Two costimulatory proteins, CD28 and ICAM-1, resident on human naïve CD4+ T cells were compared for participation in differentiation. Under controlled conditions, and with no added cytokines, costimulation through either CD3+CD28 or CD3+CAM-1 induced differentiation to T effector and T memory cells. In contrast, costimulation through CD3+ICAM-1 induced differentiation to Treg cells whereas costimulation through CD3+CD28 did not.