The induction of tolerance by dendritic cells that have captured apoptotic cells

Langerhans Cells in Sentinel Lymph Nodes from Melanoma Patients

BACKGROUND

Langerhans cells (LCs) are professional Dendritic Cells (DCs) involved in immunoregulatory functions. At the skin level, LCs are immature. In response to tissue injuries, they migrate to regional Lymph Nodes (LNs), reaching a full maturation state. Then, they become effective antigen-presenting cells (APCs) that induce anti-cancer responses. Notably, melanoma patients present several DC alterations in the Sentinel Lymph Node (SLN), where primary antitumoral immunity is generated. LCs are the most represented DCs subset in melanoma SLNs and are expected to play a key role in the anti-melanoma response. With this paper, we aim to review the current knowledge and future perspectives regarding LCs and melanoma.

METHODS

A systematic review was carried out according to the PRISMA statement using the PubMed (MEDLINE) library from January 2004 to January 2024, searching for original studies discussing LC in melanoma.

RESULTS

The final synthesis included 15 articles. Several papers revealed significant LCs-melanoma interactions.

CONCLUSIONS

Melanoma immune escape mechanisms include SLN LC alterations, favoring LN metastasis arrival/homing and melanoma proliferation. The SLN LCs of melanoma patients are defective but not irreversibly, and their function may be restored by appropriate stimuli. Thus, LCs represent a promising target for future immunotherapeutic strategies and cancer vaccines.

Determinants for Antitumor and Protumor Effects of Programmed Cell Death

Cytotoxic anticancer therapies activate programmed cell death in the context of underlying stress and inflammatory signaling to elicit the emission of danger signals, cytokines, and chemokines. In a concerted manner, these immunomodulatory secretomes stimulate antigen presentation and T cell-mediated anticancer immune responses. In some instances, cell death-associated secretomes attract immunosuppressive cells to promote tumor progression. As it stands, cancer cell death-induced changes in the tumor microenvironment that contribute to antitumor or protumor effects remain largely unknown. This is complicated to examine because cell death is often subverted by tumors to circumvent natural, and therapy-induced, immunosurveillance. Here, we provide insights into important but understudied aspects of assessing the contribution of cell death to tumor elimination or cancer progression, including the role of tumor-associated genetics, epigenetics, and oncogenic factors in subverting immunogenic cell death. This perspective will also provide insights on how future studies may address the complex antitumor and protumor immunologic effects of cell death, while accounting for variations in tumor genetics and underlying microenvironment.

Anti-Gene IGF-I Vaccines in Cancer Gene Therapy: A Review of a Case of Glioblastoma

OBJECTIVE

Vaccines for the deadliest brain tumor - glioblastoma (GBM) - are generally based on targeting growth factors or their receptors, often using antibodies. The vaccines described in the review were prepared to suppress the principal cancer growth factor - IGF-I, using anti-gene approaches either of antisense (AS) or of triple helix (TH) type. Our objective was to increase the median survival of patients treated with AS and TH cell vaccines.

METHODOLOGY

The cells were transfected in vitro by both constructed IGF-I AS and IGF-I TH expression episomal vectors; part of these cells was co-cultured with plant phytochemicals, modulating IGF-I expression. Both AS and TH approaches completely suppressed IGF-I expression and induced MHC-1 / B7 immunogenicity related to the IGF-I receptor signal.

RESULTS

This immunogenicity proved to be stronger in IGF-I TH than in IGF-I AS-prepared cell vaccines, especially in TH / phytochemical cells. The AS and TH vaccines generated an important TCD8+ and TCD8+CD11b- immune response in treated GBM patients and increased the median survival of patients up to 17-18 months, particularly using TH vaccines; in some cases, 2- and 3-year survival was reported. These clinical results were compared with those obtained in therapies targeting other growth factors.

CONCLUSION

The anti-gene IGF-I vaccines continue to be applied in current GBM personalized medicine. Technical improvements in the preparation of AS and TH vaccines to increase MHC-1 and B7 immunogenicity have, in parallel, allowed to increase in the median survival of patients.

Decoding immunogenic cell death from a dendritic cell perspective

Dendritic cells (DCs) are myeloid cells bridging the innate and adaptive immune system. By cross-presenting tumor-associated antigens (TAAs) liberated upon spontaneous or therapy-induced tumor cell death to T cells, DCs occupy a pivotal position in the cancer immunity cycle. Over the last decades, the mechanisms linking cancer cell death to DC maturation, have been the focus of intense research. Growing evidence supports the concept that the mere transfer of TAAs during the process of cell death is insufficient to drive immunogenic DC maturation unless this process is coupled with the release of immunomodulatory signals by dying cancer cells. Malignant cells succumbing to a regulated cell death variant called immunogenic cell death (ICD), foster a proficient interface with DCs, enabling their immunogenic maturation and engagement of adaptive immunity against cancer. This property relies on the ability of ICD to exhibit pathogen-mimicry hallmarks and orchestrate the emission of a spectrum of constitutively present or de novo-induced danger signals, collectively known as damage-associated molecular patterns (DAMPs). In this review, we discuss how DCs perceive and decode danger signals emanating from malignant cells undergoing ICD and provide an outlook of the major signaling and functional consequences of this interaction for DCs and antitumor immunity.

Efferocytosis: An accomplice of cancer immune escape

The clearance of apoptotic cells by efferocytes such as macrophages and dendritic cells is termed as "efferocytosis", it plays critical roles in maintaining tissue homeostasis in multicellular organisms. Currently, available studies indicate that efferocytosis-related molecules and pathways are tightly associated with cancer development, metastasis and treatment resistance, efferocytosis also induces an immunosuppressive tumor microenvironment and assists cancer cells escape from immune surveillance. In this study, we reviewed the underlying mechanisms of efferocytosis in mediating the occurrence of cancer immune escape, and then emphatically summarized the strategies of using efferocytosis as therapeutic target to enhance the anti-tumor efficacies of immune checkpoint inhibitors, hoping to provide powerful evidences for more effective therapeutic regimens of malignant tumors.

The cancer-immunity cycle: Indication, genotype, and immunotype

The cancer-immunity cycle provides a framework to understand the series of events that generate anti-cancer immune responses. It emphasizes the iterative nature of the response where the killing of tumor cells by T cells initiates subsequent rounds of antigen presentation and T cell stimulation, maintaining active immunity and adapting it to tumor evolution. Any step of the cycle can become rate-limiting, rendering the immune system unable to control tumor growth. Here, we update the cancer-immunity cycle based on the remarkable progress of the past decade. Understanding the mechanism of checkpoint inhibition has evolved, as has our view of dendritic cells in sustaining anti-tumor immunity. We additionally account for the role of the tumor microenvironment in facilitating, not just suppressing, the anti-cancer response, and discuss the importance of considering a tumor's immunological phenotype, the "immunotype". While these new insights add some complexity to the cycle, they also provide new targets for research and therapeutic intervention.

Controlling Antigen Fate in Therapeutic Cancer Vaccines by Targeting Dendritic Cell Receptors

Antigen-presenting cells (APCs) orchestrate immune responses and are therefore of interest for the targeted delivery of therapeutic vaccines. Dendritic cells (DCs) are professional APCs that excel in presentation of exogenous antigens toward CD4+ T helper cells, as well as cytotoxic CD8+ T cells. DCs are highly heterogeneous and can be divided into subpopulations that differ in abundance, function, and phenotype, such as differential expression of endocytic receptor molecules. It is firmly established that targeting antigens to DC receptors enhances the efficacy of therapeutic vaccines. While most studies emphasize the importance of targeting a specific DC subset, we argue that the differential intracellular routing downstream of the targeted receptors within the DC subset should also be considered. Here, we review the mouse and human receptors studied as target for therapeutic vaccines, focusing on antibody and ligand conjugates and how their targeting affects antigen presentation. We aim to delineate how targeting distinct receptors affects antigen presentation and vaccine efficacy, which will guide target selection for future therapeutic vaccine development.

Treatment of in vitro generated Langerhans cells with JAK-STAT inhibitor reduces their inflammatory potential

Alopecia areata (AA) is a condition in which hair is lost in small regions or over the entire body. It has a prevalence of 1 in 1000 and has a great impact on psychological wellbeing. AA is generally considered an autoimmune disease in which a collapse of the immune privilege system of the hair follicle has shown to play an important role, potentially driven by interferon gamma (IFN-γ). The most prominent cells located in or around the hair follicle in AA are Langerhans cells, CD4+ or CD8+ T cells, macrophages and mast cells. Langerhans cells, specialized dendritic cells, are resident in the epidermis and are known to associate with hair follicles. Therefore, we aimed to develop in vitro generated Langerhans cells contributing as an in vitro model of disease. In vitro models provide insight into the behaviour of cells and are a valuable tool before being in need of an animal model or patient samples. For this, Langerhans-like cells were generated from CD14+ monocytes in the presence of GM-CSF and TGF-β. After 10 days of cell culture, Langerhans-like cells express CD207 and CD1a but lack CD209 expression as well as Birbeck granules. Next, Langerhans-like cells were exposed to inflammatory conditions and the effect of different AA treatments was investigated. All treatments-diphencyprone contact immunotherapy, UV-B light therapy and JAK-STAT inhibition-affect the expression of costimulatory and skin-homing markers on Langerhans-like cells. Importantly, also the T cell stimulatory capacity of Langerhans-like cells was significantly reduced following treatment under inflammatory conditions. Noteworthy, JAK-STAT inhibition outperformed conventional AA treatments. In conclusion, our findings demonstrate that in vitro generated Langerhans-like cells can be used as a model of disease. Moreover, JAK-STAT inhibition may become a valuable new approach for the treatment of AA.

Unlocking the power of NOX2: A comprehensive review on its role in immune regulation

Reactive oxygen species (ROS) are a family of highly reactive molecules with numerous, often pleiotropic functions within the cell and the organism. Due to their potential to destroy biological structures such as membranes, enzymes and organelles, ROS have long been recognized as harmful yet unavoidable by-products of cellular metabolism leading to "oxidative stress" unless counterbalanced by cellular anti-oxidative defense mechanisms. Phagocytes utilize this destructive potential of ROS released in high amounts to defend against invading pathogens. In contrast, a regulated and fine-tuned release of "signaling ROS" (sROS) provides essential intracellular second messengers to modulate central aspects of immunity, including antigen presentation, activation of antigen presenting cells (APC) as well as the APC:T cell interaction during T cell activation. This regulated release of sROS is foremost attributed to the specialized enzyme NADPH-oxidase (NOX) 2 expressed mainly in myeloid cells such as neutrophils, macrophages and dendritic cells (DC). NOX-2-derived sROS are primarily involved in immune regulation and mediate protection against autoimmunity as well as maintenance of self-tolerance. Consequently, deficiencies in NOX2 not only result in primary immune-deficiencies such as Chronic Granulomatous Disease (CGD) but also lead to auto-inflammatory diseases and autoimmunity. A comprehensive understanding of NOX2 activation and regulation will be key for successful pharmaceutical interventions of such ROS-related diseases in the future. In this review, we summarize recent progress regarding immune regulation by NOX2-derived ROS and the consequences of its deregulation on the development of immune disorders.

LXR signaling controls homeostatic dendritic cell maturation

Dendritic cells (DCs) mature in an immunogenic or tolerogenic manner depending on the context in which an antigen is perceived, preserving the balance between immunity and tolerance. Whereas the pathways driving immunogenic maturation in response to infectious insults are well-characterized, the signals that drive tolerogenic maturation during homeostasis are still poorly understood. We found that the engulfment of apoptotic cells triggered homeostatic maturation of type 1 conventional DCs (cDC1s) within the spleen. This maturation process could be mimicked by engulfment of empty, nonadjuvanted lipid nanoparticles (LNPs), was marked by intracellular accumulation of cholesterol, and was highly specific to cDC1s. Engulfment of either apoptotic cells or cholesterol-rich LNPs led to the activation of the liver X receptor (LXR) pathway, which promotes the efflux of cellular cholesterol, and repressed genes associated with immunogenic maturation. In contrast, simultaneous engagement of TLR3 to mimic viral infection via administration of poly(I:C)-adjuvanted LNPs repressed the LXR pathway, thus delaying cellular cholesterol efflux and inducing genes that promote T cell-mediated immunity. These data demonstrate that conserved cellular cholesterol efflux pathways are differentially regulated in tolerogenic versus immunogenic cDC1s and suggest that administration of nonadjuvanted cholesterol-rich LNPs may be an approach for inducing tolerogenic DC maturation.

Regulation of immunological tolerance by the p53-inhibitor iASPP

Maintenance of immunological homeostasis between tolerance and autoimmunity is essential for the prevention of human diseases ranging from autoimmune disease to cancer. Accumulating evidence suggests that p53 can mitigate phagocytosis-induced adjuvanticity thereby promoting immunological tolerance following programmed cell death. Here we identify Inhibitor of Apoptosis Stimulating p53 Protein (iASPP), a negative regulator of p53 transcriptional activity, as a regulator of immunological tolerance. iASPP-deficiency promoted lung adenocarcinoma and pancreatic cancer tumorigenesis, while iASPP-deficient mice were less susceptible to autoimmune disease. Immune responses to iASPP-deficient tumors exhibited hallmarks of immunosuppression, including activated regulatory T cells and exhausted CD8+ T cells. Interestingly, iASPP-deficient tumor cells and tumor-infiltrating myeloid cells, CD4+, and γδ T cells expressed elevated levels of PD-1H, a recently identified transcriptional target of p53 that promotes tolerogenic phagocytosis. Identification of an iASPP/p53 axis of immune homeostasis provides a therapeutic opportunity for both autoimmune disease and cancer.

A new platform for autoimmune diseases. Inducing tolerance with liposomes encapsulating autoantigens

Autoimmune diseases (AIDs) are caused by the loss of self-tolerance and destruction of tissues by the host's immune system. Several antigen-specific immunotherapies, focused on arresting the autoimmune attack, have been tested in clinical trials with discouraging results. Therefore, there is a need for innovative strategies to restore self-tolerance safely and definitively in AIDs. We previously demonstrated the therapeutic efficacy of phosphatidylserine (PS)-liposomes encapsulating autoantigens in experimental type 1 diabetes and multiple sclerosis. Here, we show that PS-liposomes can be adapted to other autoimmune diseases by simply replacing the encapsulated autoantigen. After administration, they are distributed to target organs, captured by phagocytes and interact with several immune cells, thus exerting a tolerogenic and immunoregulatory effect. Specific PS-liposomes demonstrate great preventive and therapeutic efficacy in rheumatoid arthritis and myasthenia gravis. Thus, this work highlights the therapeutic potential of a platform for several autoimmunity settings, which is specific, safe, and with long-term effects.

Concomitant pharmacologic medications influence the clinical outcomes of granulocyte and monocyte adsorptive apheresis in patients with ulcerative colitis: A multicenter retrospective cohort study

BACKGROUND

Granulocyte and monocyte adsorptive apheresis (GMA) with Adacolumn has been used as a remission induction therapy for patients with active ulcerative colitis (UC). Herein, we investigated the influence of concomitant medications in the remission induction of GMA in patients with active UC.

METHODS

This multicenter retrospective cohort study included patients with UC underwent GMA in five independent institutions in Japan from January 2011 to July 2021. Factors including concomitant medications associated with clinical remission (CR) were analyzed statistically.

RESULT

A total of 133 patients were included. Seventy-four patients achieved a CR after GMA. The multivariable analysis revealed that concomitant medication with 5-aminosalicylic acid, Mayo endoscopic subscore (MES), and concomitant medication with immunosuppressors (IMs) remained as predictors of CR after GMA. In the subgroup analysis in patients with MES of 2, concomitant medication with IMs was demonstrated as a significant negative factor of CR after GMA (P = .042, OR 0.354). Seventy-four patients who achieved CR after GMA were followed up for 52 weeks. In the multivariable analysis, the maintenance therapy with IMs was demonstrated as a significant positive factor of sustained CR up to 52 weeks (P = .038, OR 2.214). Furthermore, the rate of sustained CR in patients with biologics and IMs was significantly higher than that in patients with biologics only (P = .002).

CONCLUSION

GMA was more effective for patients with active UC that relapsed under treatment without IMs. Furthermore, the addition of IMs should be considered in patients on maintenance therapy with biologics after GMA.

The emerging role of noncoding RNAs in systemic lupus erythematosus: new insights into the master regulators of disease pathogenesis

Auto-immune diseases are a form of chronic disorders in which the immune system destroys the body's cells due to a loss of tolerance to self-antigens. Systemic lupus erythematosus (SLE), identified by the production of autoantibodies in different body parts, is one of the most well-known examples of these diseases. Although the etiology of SLE is unclear, the disease's progression may be affected by genetic and environmental factors. As studies in twins provide adequate evidence for genetic involvement in the SLE, other phenomena such as metallization, histone modifications, and alterations in the expression of noncoding RNAs (ncRNAs) also indicate the involvement of epigenetic factors in this disease. Among all the epigenetic alterations, ncRNAs appear to have the most crucial contribution to the pathogenesis of SLE. The ncRNAs' length and size are divided into three main classes: micro RNAs, long noncoding RNAs (LncRNA), and circular RNAs (circRNAs). Accumulating evidence suggests that dysregulations in these ncRNAs contributed to the pathogenesis of SLE. Hence, clarifying the function of these groups of ncRNAs in the pathophysiology of SLE provides a deeper understanding of the disease. It also opens up new opportunities to develop targeted therapies for this disease.

Immunogenic cell death triggered by impaired deubiquitination in multiple myeloma relies on dysregulated type I interferon signaling

Introduction

Proteasome inhibition is first line therapy in multiple myeloma (MM). The immunological potential of cell death triggered by defects of the ubiquitin-proteasome system (UPS) and subsequent perturbations of protein homeostasis is, however, less well defined.

Methods

In this paper, we applied the protein homeostasis disruptors bortezomib (BTZ), ONX0914, RA190 and PR619 to various MM cell lines and primary patient samples to investigate their ability to induce immunogenic cell death (ICD).

Results

Our data show that while BTZ treatment triggers sterile type I interferon (IFN) responses, exposure of the cells to ONX0914 or RA190 was mostly immunologically silent. Interestingly, inhibition of protein de-ubiquitination by PR619 was associated with the acquisition of a strong type I IFN gene signature which relied on key components of the unfolded protein and integrated stress responses including inositol-requiring enzyme 1 (IRE1), protein kinase R (PKR) and general control nonderepressible 2 (GCN2). The immunological relevance of blocking de-ubiquitination in MM was further reflected by the ability of PR619-induced apoptotic cells to facilitate dendritic cell (DC) maturation via type I IFN-dependent mechanisms.

Conclusion

Altogether, our findings identify de-ubiquitination inhibition as a promising strategy for inducing ICD of MM to expand current available treatments.

Induction of immunogenic cell death by novel platinum-based anticancer agents

Traditional platinum-based anticancer drugs, led by cisplatin, play an important role in chemotherapy. However, the development of platinum compounds is limited due to serious toxicity and side effects. In recent years, studies have showed that immunogenic cell death (ICD) may be one of the potential action mechanisms of classical platinum drugs, such as oxaliplatin. This strategy combining chemotherapy and immunotherapy can effectively utilize the body's immune system to help platinum compounds to fight against tumors, and the dose can be appropriately reduced to limit toxic side effects. The induction of ICD by platinum compounds has become a research hotspot and one of the future development directions of metal drugs. Here, the progress of platinum compounds were collected and comprehensively summarized, their capacity of ICD induction and mechanism of action are exposed, providing reference for the design and synthesis of new anticancer platinum ICD inducers.

Antigen targeting to dendritic cells: Still a place in future immunotherapy?

The hallmark of DCs is their potent and outstanding capacity to activate naive resting T cells. As such, DCs are the sentinels of the immune system and instrumental for the induction of immune responses. This is one of the reasons, why DCs became the focus of immunotherapeutical strategies to fight infections, cancer, and autoimmunity. Besides the exploration of adoptive DC-therapy for which DCs are generated from monocytes or purified in large numbers from the blood, alternative approaches were developed such as antigen targeting of DCs. The idea behind this strategy is that DCs resident in patients' lymphoid organs or peripheral tissues can be directly loaded with antigens in situ. The proof of principle came from mouse models; subsequent translational studies confirmed the potential of this therapy. The first clinical trials demonstrated feasibility and the induction of T-cell immunity in patients. This review will cover: (i) the historical aspects of antigen targeting, (ii) briefly summarize the biology of DCs and the immunological functions upon which this concept rests, (iii) give an overview on attempts to target DC receptors with antibodies or (glycosylated) ligands, and finally, (iv) discuss the translation of antigen targeting into clinical therapy.

The role of dendritic cells in the immunomodulation to implanted biomaterials

Considering the substantial role played by dendritic cells (DCs) in the immune system to bridge innate and adaptive immunity, studies on DC-mediated immunity toward biomaterials principally center on their adjuvant effects in facilitating the adaptive immunity of codelivered antigens. However, the effect of the intrinsic properties of biomaterials on dendritic cells has not been clarified. Recently, researchers have begun to investigate and found that biomaterials that are nonadjuvant could also regulate the immune function of DCs and thus affect subsequent tissue regeneration. In the case of proteins adsorbed onto biomaterial surfaces, their intrinsic properties can direct their orientation and conformation, forming “biomaterial-associated molecular patterns (BAMPs)”. Thus, in this review, we focused on the intrinsic physiochemical properties of biomaterials in the absence of antigens that affect DC immune function and summarized the underlying signaling pathways. Moreover, we preliminarily clarified the specific composition of BAMPs and the interplay between some key molecules and DCs, such as heat shock proteins (HSPs) and high mobility group box 1 (HMGB1). This review provides a new direction for future biomaterial design, through which modulation of host immune responses is applicable to tissue engineering and immunotherapy.

Emerging roles of neutrophils in immune homeostasis

Neutrophils, the most abundant innate immune cells, play essential roles in the innate immune system. As key innate immune cells, neutrophils detect intrusion of pathogens and initiate immune cascades with their functions; swarming (arresting), cytokine production, degranulation, phagocytosis, and projection of neutrophil extracellular trap. Because of their short lifespan and consumption during immune response, neutrophils need to be generated consistently, and generation of newborn neutrophils (granulopoiesis) should fulfill the environmental/systemic demands for training in cases of infection. Accumulating evidence suggests that neutrophils also play important roles in the regulation of adaptive immunity. Neutrophil-mediated immune responses end with apoptosis of the cells, and proper phagocytosis of the apoptotic body (efferocytosis) is crucial for initial and post resolution by producing tolerogenic innate/adaptive immune cells. However, inflammatory cues can impair these cascades, resulting in systemic immune activation; necrotic/pyroptotic neutrophil bodies can aggravate the excessive inflammation, increasing inflammatory macrophage and dendritic cell activation and subsequent T_H1/T_H17 responses contributing to the regulation of the pathogenesis of autoimmune disease. In this review, we briefly introduce recent studies of neutrophil function as players of immune response.

Novel Radiation Therapy Paradigms and Immunomodulation: Heresies and Hope

Radiation therapy benefits the majority of patients across the spectrum of cancer types. However, both local and distant tumor recurrences limit its clinical success. While departing from the established tenet of fractionation in clinical radiotherapy, ablative-intensity hypofractionated radiotherapy, especially stereotactic radiosurgery and stereotactic ablative radiotherapy, has emerged as an alternative paradigm achieving unprecedented rates of local tumor control. Direct tumor cell killing has been assumed to be the primary therapeutic mode of action of such ablative radiation. But with increasing recognition that tumor responses also depend on the immunostimulatory or immunosuppressive status of the tumor microenvironment, the immunologic effect of ablative radiotherapy is emerging as a key contributor to antitumor response. More recently, novel radiation modalities, such as spatially fractionated radiotherapy and ultrahigh dose rate FLASH irradiation, that venture even further from conventional paradigms have shown promise of increasing the therapeutic index of radiation therapy with the potential of immunomodulation. Here, we review the immunomodulatory impact of novel radiation therapy paradigms, heretofore considered radiobiological heresies, a deeper understanding of which is imperative to realizing fully their potential for more curative cancer therapy.

Convection enhanced delivery of light responsive antigen capturing oxygen generators for chemo-phototherapy triggered adaptive immunity

In recent years, combination therapy has emerged as the cornerstone of clinical practice in treating glioblastoma multiforme. However, their ability to trigger and leverage the body's adaptive immunity has rarely been studied. Tumour heterogeneity, the presence of the blood-brain barrier, and an immunosuppressive tumor microenvironment play a crucial role in the 90% local tumor recurrence post-treatment. Herein, we report an improved combination therapy approach capable of stimulating an immune response that utilizes Light responsive antigen-capturing oxygen generators (LAGs). The engineered LAGs loaded with a non-genotoxic molecule, Nutlin-3a, and a photosensitizer, Protoporphyrin IX, can release the payload on-demand when exposed to light of a specific wavelength. The in-situ oxygen generation capability of LAGs enables tumor oxygenation enhancement, thereby alleviating the tumor hypoxia and enhancing the efficacy of chemo-photodynamic therapy. Furthermore, by modulating the surface properties of LAGs, we demonstrated that the tumor-derived protein antigens released can be captured and retained in-situ, which improves antigen uptake and presentation by the antigen-presenting cells. Dual drug-loaded LAGs (DD-LAGs) upregulated the expression of cell surface CD83 maturation and CD86 costimulatory markers on monocyte-derived-dendritic cells, suggesting intrinsic immune adjuvancy. In the presence of 3D printed hypoxic U87 spheroids (h-U87), DD-LAGs induced cancer cell death, upregulated IL-1β, and downregulated IL-10 resulting in CD3⁺, helper CD4⁺, and cytotoxic CD8⁺ proliferation. Finally, we have investigated convection-enhanced delivery as a potential route of administration for DD-LAGs. Our work presents a novel strategy to induce tumor cell death both during and post-treatment, thereby reducing the possibility of recurrence.

Harnessing Tolerogenic Histone Peptide Epitopes From Nucleosomes for Selective Down-Regulation of Pathogenic Autoimmune Response in Lupus (Past, Present, and Future)

Autoantigen-directed tolerance can be induced by certain nucleosomal histone peptide epitope/s in nanomolar dosage leading to sustained remission of disease in mice with spontaneous SLE. By contrast, lupus is accelerated by administration of intact (whole) histones, or whole nucleosomes in microparticles from apoptotic cells, or by post-translationally acetylated histone-peptides. Low-dose therapy with the histone-peptide epitopes simultaneously induces TGFβ and inhibits IL-6 production by DC in vivo, especially pDC, which then induce CD4+CD25+ Treg and CD8+ Treg cells that suppress pathogenic autoimmune response. Both types of induced Treg cells are FoxP3+ and act by producing TGFβ at close cell-to-cell range. No anaphylactic adverse reactions, or generalized immunosuppression have been detected in mice injected with the peptides, because the epitopes are derived from evolutionarily conserved histones in the chromatin; and the peptides are expressed in the thymus during ontogeny, and their native sequences have not been altered. The peptide-induced Treg cells can block severe lupus on adoptive transfer reducing inflammatory cell reaction and infiltration in the kidney. In Humans, similar potent Treg cells are generated by the histone peptide epitopes in vitro in lupus patients’ PBMC, inhibiting anti-dsDNA autoantibody and interferon production. Furthermore, the same types of Treg cells are generated in lupus patients who are in very long-term remission (2-8 years) after undergoing autologous hematopoietic stem cell transplantation. These Treg cells are not found in lupus patients treated conventionally into clinical remission (SLEDAI of 0); and consequently they still harbor pathogenic autoimmune cells, causing subclinical damage. Although antigen-specific therapy with pinpoint accuracy is suitable for straight-forward organ-specific autoimmune diseases, Systemic Lupus is much more complex. The histone peptide epitopes have unique tolerogenic properties for inhibiting Innate immune cells (DC), T cells and B cell populations that are both antigen-specifically and cross-reactively involved in the pathogenic autoimmune response in lupus. The histone peptide tolerance is a natural and non-toxic therapy suitable for treating early lupus, and also maintaining lupus patients after toxic drug therapy. The experimental steps, challenges and possible solutions for successful therapy with these peptide epitopes are discussed in this highly focused review on Systemic Lupus.

The synergistic strategies for the immuno-oncotherapy with photothermal nanoagents

Immuno-oncotherapy has shown great promise for the cure of late-stage and metastatic cancer. Great efforts have tried to improve the overall response rate (ORR) and to reduce the immune-related adverse events (irAEs). Antigen presentation, T cell activation and killing are interlocking and distinct steps to initiate effective anti-tumor immune responses. Aiming to overcome the tumor immune evasion whose mechanisms include limited release of neoantigen, suppressed infiltration of antigen-presenting cells (APCs) and T cells, and the expression of immune checkpoints (ICPs), combinational therapeutic strategies have shown great potential by activating the anti-tumor immune responses together with deactivating immunosuppressive conditions simultaneously. In this direction, photothermal therapy (PTT) has attracted attention due to the efficient ablation of tumor cells, of which the released immunogenic tumor debris can activate host immune responses. The combination of immunoadjuvants and/or ICP inhibitors can boost the anti-tumor immune responses, realizing PTT-synergized immuno-oncotherapy. In this regard, numerous multifunctional nanomaterials have been designed with integration of photothermal and immuno-oncotherapeutic agents into one package via well-designed surface modification and functionalization. This review summarizes the recent studies on the synergistic strategies for the immuno-oncotherapy based on photothermal nanoagents and the mechanisms that trigger the systemic anti-tumor immune responses and PTT-synergized immuno-oncotherapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Immune Milieu Established by Postpartum Liver Involution Promotes Breast Cancer Liver Metastasis

In rodents, we identified a physiologic process within the normal liver that creates a pre-metastatic niche. This physiology is weaning-induced liver involution, characterized by hepatocyte cell death, immune influx, and extracellular matrix remodeling. Here, using weaning-induced liver involution as a model of a physiologically regulated pro-metastatic niche, we investigate how liver involution supports breast cancer metastasis. Liver metastases were induced in BALB/c immune competent hosts by portal vein injection of D2OR (low metastatic) or D2A1 (high metastatic) mouse mammary tumor cells. Tumor incidence and multiplicity increased in involution hosts with no evidence of a proliferation advantage. D2OR tumor cell extravasation, seeding, and early survival were not enhanced in the involuting group compared to the nulliparous group. Rather, the involution metastatic advantage was observed at 14 days post tumor cell injection. This metastatic advantage associated with induction of immune tolerance in the involution host liver, reproductive state dependent intra-tumoral immune composition, and CD8-dependent suppression of metastases in nulliparous hosts. Our findings suggest that the normal postpartum liver is in an immune suppressed state, which can provide a pro-metastatic advantage to circulating breast cancer cells. Potential relevance to women is suggested as a postpartum diagnosis of breast cancer is an independent predictor of liver metastasis.

Hepatic Dendritic Cells in the Development and Progression of Metabolic Steatohepatitis

Metabolic Associated Fatty liver disease (MAFLD) is a global health problem and represents the most common cause of chronic liver disease in the world. MAFLD spectrum goes from simple steatosis to cirrhosis, in between metabolic steatohepatitis with progressive fibrosis, which pathogenesis is not completely understood. Hence, the role of the immune system has become an important fact in the trigger of inflammatory cascades in metabolic steatohepatitis and in the activation of hepatic stellate cells (HSCs). Among, the more studied immune cells in the pathogenesis of MAFLD are macrophages, T cells, natural killer and dendritic cells. In particular, hepatic dendritic cells had recently attracted a special attention, with a dual role in the pathogenesis of MAFLD. These cells have the capacity to switch from a tolerant state to active state inducing an inflammatory cascade. Furthermore, these cells play a role in the lipid storage within the liver, having, thus providing a crucial nexus between inflammation and lipid metabolism. In this review, we will discuss the current knowledge on the dual role of dendritic cells in lipid accumulation, as wells as in the triggering of hepatic inflammation and hepatocytes cell death in metabolic steatohepatitis.

Soluble N-Acetylgalactosamine-Modified Antigens Enhance Hepatocyte-Dependent Antigen Cross-Presentation and Result in Antigen-Specific CD8+ T Cell Tolerance Development

Hepatocytes compose up to 80% of the total liver and have been indicated as important players in the induction of immunologic tolerance in this organ. We show that hepatocytes possess the molecular machinery required for the cross-presentation of extracellular antigens. Using a derivative of the model antigen ovalbumin (OVA) covalently modified with a polymer containing multiple N-acetylgalactosamine residues (pGal-OVA) that enhance extracellular antigen uptake by mimicking the glycome of apoptotic debris, we show efficient hepatocyte-dependent induction of cross-tolerance of both adoptively transferred OT-I cells and endogenous OVA-specific CD8+ T lymphocytes, for example inducing tolerance to OVA-expressing skin transplants. Our study confirms that hepatocytes are capable of inducing peripheral tolerogenesis and provides proof of concept that they may be a valuable candidate for in vivo targeted tolerogenic treatments.

Granulocyte and monocyte adsorptive apheresis induces apoptosis of neutrophils and release of a novel chemoattractant for desensitization of interleukin-8 response - In vitro and in vivo results

OBJECTIVE

Apoptotic cells participate in maintenance of homeostasis of the adaptive immune system. Granulocyte/monocyte adsorptive apheresis (GMA) performed with an Adacolumn has been shown to have clinical efficacy together with immunomodulatory effects for immune-mediated disorder cases, such as inflammatory bowel disease (IBD) or psoriatic arthritis. Although induction of apoptosis in neutrophils by GMA has been observed, the detailed mechanism remains unclear.

METHODS

To focus on phagocytosis-induced cell death (PICD) that induces apoptotic neutrophils, a comparative study utilizing a GMA-carrier (leukocyte adsorbing carrier for Adacolumn) and yeast particles was performed with in vitro and in vivo examinations.

RESULTS

L-selectin was significantly (P = 0.0133) shed, reactive oxygen species (ROS) production was promoted (P = 0.0019), and apoptosis induction was enhanced (P = 0.0087) by peripheral blood co-cultured with the GMA-carrier or yeast particles as compared to incubated blood alone. Furthermore, degranulation of myeloperoxidase, elastase, and lactoferrin was increased by both treatments, while the highest level of interleukin-1 receptor antagonist release was found with GMA-carrier treatment (P = 0.0087) as compared to the yeast particles. Plasma from blood treated with the GMA-carrier showed chemotactic activity, and suppressed neutrophil migration to IL-8 and LTB₄. In vivo results demonstrated that neutrophil chemotaxis to IL-8 was desensitized (P = 0.0078) in rabbits following GMA apheresis, while CXCR1 and CXCR2 expressions in neutrophils were reduced by exposing peripheral blood to the GMA-carrier.

CONCLUSIONS

GMA may regulate the immune system in patients with an immune-mediated disorder by inducing a biological response of neutrophils with a PICD-like reaction.

Immunologic evaluation and genetic defects of apoptosis in patients with autoimmune lymphoproliferative syndrome (ALPS)

Apoptosis plays an important role in controlling the adaptive immune response and general homeostasis of the immune cells, and impaired apoptosis in the immune system results in autoimmunity and immune dysregulation. In the last 25 years, inherited human diseases of the Fas-FasL pathway have been recognized. Autoimmune lymphoproliferative syndrome (ALPS) is an inborn error of immunity, characterized clinically by nonmalignant and noninfectious lymphoproliferation, autoimmunity, and increased risk of lymphoma due to a defect in lymphocyte apoptosis. The laboratory hallmarks of ALPS are an elevated percentage of T-cell receptor αβ double negative T cells (DNTs), elevated levels of vitamin B12, soluble FasL, IL-10, IL-18 and IgG, and defective in vitro Fas-mediated apoptosis. In order of frequency, the genetic defects associated with ALPS are germinal and somatic ALPS-FAS, ALPS-FASLG, ALPS-CASP10, ALPS-FADD, and ALPS-CASP8. Partial disease penetrance and severity suggest the combination of germline and somatic FAS mutations as well as other risk factor genes. In this report, we summarize human defects of apoptosis leading to ALPS and defects that are known as ALPS-like syndromes that can be clinically similar to, but are genetically distinct from, ALPS. An efficient genetic and immunological diagnostic approach to patients suspected of having ALPS or ALPS-like syndromes is essential because this enables the establishment of specific therapeutic strategies for improving the prognosis and quality of life of patients.

Autoantigen-specific immune tolerance in pathological and physiological cell death: Nanotechnology comes into view

Apoptotic cells are tolerogenic and can present self-antigens in the absence of inflammation, to antigen-presenting cells by the process of efferocytosis, resulting in anergy and depletion of immune effector cells. This tolerance is essential to maintain immune homeostasis and prevent systemic autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Consequently, effective efferocytosis can result in the induction of immune tolerance mediated via triggering modulatory lymphocytes and anti-inflammatory responses. Furthermore, several distinct soluble factors, receptors and pathways have been found to be involved in the efferocytosis, which are able to regulate immune tolerance by lessening antigen presentation, inhibition of T-cell proliferation and induction of regulatory T-cells. Some newly developed nanotechnology-based approaches can induce antigen-specific immunological tolerance without any systemic immunosuppression. These strategies have been explored to reverse autoimmune responses induced against various protein antigens in different diseases. In this review, we describe some nanotechnology-based approaches for the maintenance of self-tolerance using the apoptotic cell clearance process (efferocytosis) that may be able to induce immune tolerance and treat autoimmune diseases.

Sensing Tissue Damage by Myeloid C-Type Lectin Receptors

After both sterile and infectious insults, damage is inflicted on tissues leading to accidental or programmed cell death. In addition, events of programmed cell death also take place under homeostatic conditions, such as in embryo development or in the turnover of hematopoietic cells. Mammalian tissues are seeded with myeloid immune cells, which harbor a plethora of receptors that allow the detection of cell death, modulating immune responses. The myeloid C-type lectin receptors (CLRs) are one of the most prominent families of receptors involved in tailoring immunity after sensing dead cells. In this chapter, we will cover a diversity of signals arising from different forms of cell death and how they are recognized by myeloid CLRs. We will also explore how myeloid cells develop their sentinel function, exploring how some of these CLRs identify cell death and the type of responses triggered thereof. In particular, we will focus on DNGR-1 (CLEC9A), Mincle (CLEC4E), CLL-1 (CLEC12A), LOX-1 (OLR1), CD301 (CLEC10A) and DEC-205 (LY75) as paradigmatic death-sensing CLRs expressed by myeloid cells. The molecular processes triggered after cell death recognition by myeloid CLRs contribute to the regulation of immune responses in pathologies associated with tissue damage, such as infection, autoimmunity and cancer. A better understanding of these processes may help to improve the current approaches for therapeutic intervention.

Efficacy of Granulocyte and Monocyte Adsorptive Apheresis in Patients With Inflammatory Bowel Disease Showing Lost Response to Infliximab

BACKGROUND AND AIMS

In inflammatory bowel disease [IBD] patients, antibody-to-infliximab [ATI] generation is responsible for loss of response [LOR] and infusion reaction [IR] to infliximab. An immuno-therapeutic approach is considered an option to overcome LOR. Granulocyte/monocyte adsorptive apheresis [GMA] using an Adacolumn has been shown to have clinical efficacy together with immunomodulatory effects in IBD patients.

METHODS

We developed an ATI-CAI assay utilizing a C1q immobilized plate and applied it to measure ATI in patients who were receiving infliximab, including 56 with sustained response, 76 with LOR and six with IR. Furthermore, 14 patients with LOR and two with paradoxical skin reactions who received infliximab + GMA combination therapy were analysed.

RESULTS

Fourteen patients with LOR, seven with Crohn's disease and seven with ulcerative colitis, showed significantly improved clinical indices [p = 0.0009], and decreased ATI [p = 0.0171] and interleukin-6 [p = 0.0537] levels at week 8 following initiation of infliximab + GMA therapy. Nine patients who received combination therapy achieved remission, which was maintained to week 24 with infliximab alone. Additionally, cutaneous lesions in two patients with IR were improved. ATI-CAI assay efficiency was not influenced by infliximab concentration during the test. Pre- and post-infliximab infusion ATI levels were not different. Patients with ATI greater than the 0.153 μg/mL cut-off value were likely to experience LOR [odds ratio 3.0].

CONCLUSIONS

Patients who received infliximab + GMA therapy appeared to regain clinical response to infliximab by a decrease in ATI level. Furthermore, the concentration of infliximab in the test did not influence ATI measurement, but was associated with clinical response.

Biomaterials as Local Niches for Immunomodulation

A major function of the immune system is to detect threat from foreign invaders, tissue damage, or cancer and to mount a counter response that resolves the threat, restores homeostasis, and supplies immunological memory to prevent a second assault. Our increasing understanding of the immune system has opened up numerous avenues for modulating immune responses against infections, cancer, and autoimmunity. However, agents used for immunomodulation have been traditionally administered systemically via bolus injection, leading to unintended consequences by disrupting homeostasis at nontarget sites. Consequently, systemic hyperactivation and hypoactivation can result from bolus administration of immune-activators and immunosuppressants, respectively. Macroscale biomaterial scaffolds can instead be placed at the intended target site to provide both localized, controlled release of immunomodulatory agents and control over local immune cell trafficking and function, potentially maximizing therapeutic efficacy and limiting systemic exposure. These scaffolds have found utility in the area of cancer immunotherapy, especially in situ cancer vaccination where controlled release of factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and the local presentation of tumor antigen and danger signals lead to the recruitment of immature dendritic cells and facilitate their activation and antigen presentation. These cells eventually migrate into secondary lymphoid organs where they prime tumor specific T cells for downstream tumor clearance. Scaffolds can also be used in adoptive T cell therapy to generate large numbers of potent antigen specific T cells or chimeric antigen receptor (CAR) T cells in vitro for subsequent delivery to patients. Macroscale biomaterial scaffolds have also found utility beyond cancer immunotherapy and have been developed to promote immune tolerance by regulatory T cell induction and to expedite tissue regeneration. The design of these macroscale biomaterial scaffolds considers their biocompatibility, biodegradability, mode of delivery, porosity, and kinetics of therapeutic cargo release. Consequently, the numerous approaches that have been developed to fabricate biomaterial scaffolds are aimed at tuning these parameters to achieve the desired therapeutic outcome. This Account will discuss the use of biomaterial scaffolds as niches for immunomodulation and will focus on (1) approaches that have been used to fabricate various biomaterial systems being employed as niches for immunomodulation and (2) how these biomaterial systems have been used to modulate immune responses, specifically in area of cancer immunotherapy, where we will discuss the role of macroscale biomaterial scaffolds for in situ vaccination and in vitro T cell expansion. We will also briefly discuss the utility of biomaterial scaffolds beyond cancer, drawing examples from tolerance and tissue regeneration.

Tethering Innate Surface Receptors on Dendritic Cells: A New Avenue for Immune Tolerance Induction?

Dendritic cells (DCs) play a key role in immunity and are highly potent at presenting antigens and orienting the immune response. Depending on the environmental signals, DCs could turn the immune response toward immunity or immune tolerance. Several subsets of DCs have been described, with each expressing various surface receptors and all participating in DC-associated immune functions according to their specific skills. DC subsets could also contribute to the vicious circle of inflammation in immune diseases and establishment of immune tolerance in cancer. They appear to be appropriate targets in the control of inflammatory diseases or regulation of autoimmune responses. For all these reasons, in situ DC targeting with therapeutic antibodies seems to be a suitable way of modulating the entire immune system. At present, the field of antibody-based therapies has mainly been developed in oncology, but it is undergoing remarkable expansion thanks to a wide variety of antibody formats and their related functions. Moreover, current knowledge of DC biology may open new avenues for targeting and modulating the different DC subsets. Based on an update of pathogen recognition receptor expression profiles in human DC subsets, this review evaluates the possibility of inducing tolerant DCs using antibody-based therapeutic agents.

ASGR1 and Its Enigmatic Relative, CLEC10A

The large family of C-type lectin (CLEC) receptors comprises carbohydrate-binding proteins that require Ca²⁺ to bind a ligand. The prototypic receptor is the asialoglycoprotein receptor-1 (ASGR1, CLEC4H1) that is expressed primarily by hepatocytes. The early work on ASGR1, which is highly specific for N-acetylgalactosamine (GalNAc), established the foundation for understanding the overall function of CLEC receptors. Cells of the immune system generally express more than one CLEC receptor that serve diverse functions such as pathogen-recognition, initiation of cellular signaling, cellular adhesion, glycoprotein turnover, inflammation and immune responses. The receptor CLEC10A (C-type lectin domain family 10 member A, CD301; also called the macrophage galactose-type lectin, MGL) contains a carbohydrate-recognition domain (CRD) that is homologous to the CRD of ASGR1, and thus, is also specific for GalNAc. CLEC10A is most highly expressed on immature DCs, monocyte-derived DCs, and alternatively activated macrophages (subtype M2a) as well as oocytes and progenitor cells at several stages of embryonic development. This receptor is involved in initiation of T_H1, T_H2, and T_H17 immune responses and induction of tolerance in naïve T cells. Ligand-mediated endocytosis of CLEC receptors initiates a Ca²⁺ signal that interestingly has different outcomes depending on ligand properties, concentration, and frequency of administration. This review summarizes studies that have been carried out on these receptors.

Systemic lupus erythematosus favors the generation of IL-17 producing double negative T cells

Mature double negative (DN) T cells are a population of αβ T cells that lack CD4 and CD8 coreceptors and contribute to systemic lupus erythematosus (SLE). The splenic marginal zone macrophages (MZMs) are important for establishing immune tolerance, and loss of their number or function contributes to the progression of SLE. Here we show that loss of MZMs impairs the tolerogenic clearance of apoptotic cells and alters the serum cytokine profile, which in turn provokes the generation of DN T cells from self-reactive CD8⁺ T cells. Increased Ki67 expression, narrowed TCR V-beta repertoire usage and diluted T-cell receptor excision circles confirm that DN T cells from lupus-prone mice and patients with SLE undergo clonal proliferation and expansion in a self-antigen dependent manner, which supports the shared mechanisms for their generation. Collectively, our results provide a link between the loss of MZMs and the expansion of DN T cells, and indicate possible strategies to prevent the development of SLE.

Splenic marginal zone macrophages can establish immune tolerance and limit the development of systemic lupus erythematosus (SLE). Here the authors show that these cells do this by clearing apoptotic cells, and defects in these cells result in the generation of self-reactive double negative T cells that are known to contribute to SLE pathogenesis.

Bone marrow dendritic cells deficient for CD40 and IL-23p19 are tolerogenic in vitro

Objective(s):

In addition to pro-inflammatory role, dendritic cells (DCs) can also be anti-inflammatory when they acquire tolerogenic phenotype. In this study we tested the role of CD40 and IL-23p19 in antigen presenting function of bone marrow-derived DCs (BMDCs) by comparing BMDCs derived from CD40 knockout (CD40KO-DCs) and IL-23p19 (IL-23p19KO-DCs) knockout mice with those from C57BL/6 mice (Cont-DCs). We have focused on CD40 and IL-23, as these molecules have well established pro-inflammatory roles in a number of autoimmune and inflammatory diseases.

Materials and Methods:

The expression of maturation markers MHC II and co-stimulatory molecules CD40, CD80, and CD86 was analyzed by flow cytometry, while the expression of CD40 and IL-23p19 was measured by RT-PCR. The capacity of BMDCs to activate CD4+ T cells was evaluated by 3H-thymidine incorporation, and the capacity of BMDCs to uptake antigen was evaluated using fluorescent OVA and flow cytometry.

Results:

The lack of CD40 or IL-23p19 had no effect on uptake of FITC-OVA by the DCs, confirming their immature phenotype. Moreover, CD40KO-DCs had significantly reduced capacity to stimulate proliferation of CD4+ T cells. CD4+ T cells activated by CD40KO-DCs and IL-23p19KO-DCs produced significantly less IFN-γ (P-value ≤0.05), while CD4+ T cells stimulated by IL-23p19KO-DCs produced less GM-CSF and more IL-10 than Cont-DCs.

Conclusion:

This study shows that CD40KO-DCs and IL-23p19KO-DCs have a marked tolerogenic potency in vitro. Future in vivo studies should determine if and to what extent DCs lacking CD40 or IL-23 have a potential to be useful in therapy of autoimmune inflammation.

Langerhans Cells From Mice at Birth Express Endocytic- and Pattern Recognition-Receptors, Migrate to Draining Lymph Nodes Ferrying Antigen and Activate Neonatal T Cells in vivo

Antigen capturing at the periphery is one of the earliest, crucial functions of antigen-presenting cells (APCs) to initiate immune responses. Langerhans cells (LCs), the epidermal APCs migrate to draining lymph nodes (DLNs) upon acquiring antigens. An arsenal of endocytic molecules is available to this end, including lectins and pathogen recognition receptors (PRRs). However, cutaneous LCs are poorly defined in the early neonatal period. We assessed endocytic molecules expression in situ: Mannose (CD206)-, Scavenger (SRA/CD204)-, Complement (CD2l, CDllb)-, and Fc-Receptors (CD16/32, CD23) as well as CD1d, CD14, CD205, Langerin (CD207), MHCII, and TLR4 in unperturbed epidermal LCs from both adult and early neonatal mice. As most of these markers were negative at birth (day 0), LC presence was revealed with the conspicuous, epidermal LC-restricted ADPase (and confirmed with CD45) staining detecting that they were as numerous as adult ones. Unexpectedly, most LCs at day 0 expressed CD14 and CD204 while very few were MHCII+ and TLR4+. In contrast, adult LCs lacked all these markers except Langerin, CD205, CD11b, MHCII and TLR4. Intriguingly, the CD204+ and CD14+ LCs predominant at day 0, apparently disappeared by day 4. Upon cutaneous FITC application, LCs were reduced in the skin and a CD204+MHCII+FITC+ population with high levels of CD86 subsequently appeared in DLNs, with a concomitant increased percentage of CD3+CD69+ T cells, strongly suggesting that neonatal LCs were able both to ferry the cutaneous antigen into DLNs and to activate neonatal T cells in vivo. Cell cycle analysis indicated that neonatal T cells in DLNs responded with proliferation. Our study reveals that epidermal LCs are present at birth, but their repertoire of endocytic molecules and PRRs differs to that of adult ones. We believe this to be the first description of CDl4, CD204 and TLR4 in neonatal epidermal LCs in situ. Newborns' LCs express molecules to detect antigens during early postnatal periods, are able to take up local antigens and to ferry them into DLNs conveying the information to responsive neonatal T cells.

Glucose metabolism pattern of peripheral blood immune cells in myasthenia gravis patients

Background

We investigated the correlation between glucose metabolism patterns of different immune cells and the metabolic regulatory signaling pathways in myasthenia gravis (MG) and aimed to identify therapeutic targets for MG.

Methods

We isolated peripheral blood mononuclear cells (PBMCs) and sorted CD19⁺B cells, dendritic cells (DCs), CD4⁺ T cells, CD8⁺ T cells, CD4⁺CD25⁺ regulatory T cells (Tregs), CD4⁺CD25^-T cells, and T helper (Th) cells such as Th1, Th2, and Th17 cells. Then, we detected the expression levels of PI3K/AKT/mTOR-HIF-1α, GLUT1, hexokinase (HK), phosphofructokinase (PFK), and pyruvate kinase (PK) by RT-PCR, measured the oxygen consumption rate and extracellular acidification rate of ex vivo freshly sorted cells using the Seahorse XF^e96 Analyzer. In addition, we compared the glycolysis levels using these cells from the same MG patients. By performing in vitro experiments, we measured, the mRNA expression levels of mTOR, HIF-1α, B cell activating factor receptor (BAFF-R), GLUT1, HK, PFK, and PK, in addition to ECAR profiles, frequency of CD80 and CD86, and IgG levels from the culture supernatant of B cells (isolated from MG patients) treated with rapamycin and PX-478 (selective mTOR and HIF-1α inhibitor, respectively) from.

Results

Except PBMCs, Th2 and CD8⁺ T cells, the expression levels of the key enzymes involved in glycolysis and HIF-1α were significantly higher in B cells, DCs, Tregs, CD4⁺CD25^-T cells, and Th1 and Th17 cells in MG patients, and the measurement of ECAR and OCR confirmed the metabolic status. In MG patients, B cells and DCs showed significantly higher levels of glycolysis and glycolytic capacity than CD8⁺ T cells, CD4⁺ T cells and its subsets. In vitro, except IgG levels, the increased glycolysis levels, expression of key glycolytic enzymes, BAFF-R and frequency of CD80 and CD86 of B cells, could be inhibited by rapamycin and PX-478.

Conclusions

Different subtypes of immune cells in MG exhibit different glucose metabolism patterns. The mTOR-HIF-1α signaling pathway might be the immunometabolism reprogramming checkpoint of glycolysis-dependent activated B cells in MG.

Recent discoveries in dendritic cell tolerance-inducing pharmacological molecules

Dendritic cells (DCs) represent one of the most important biological tools for cellular immunotherapy purposes. There are an increasing number of phase I and II studies, where regulatory or tolerogenic DCs (TolDCs) are utilized as negative vaccines, with the aim of inducing tolerogenic outcomes in patients with various autoimmune or chronic-inflammatory diseases, as well as in transplant settings. The induction of tolerogenic properties in DCs can be achieved by altering their activation state toward expression of immunosuppressive elements and/or by achieving resistance to maturation, which leads to insufficient co-stimulatory signal delivery and inability to efficiently present antigens. In the past, one of the most efficient ways to induce DC tolerance has been the application of selected pharmacological agents which actively induce a tolerogenic transcription program or inhibit major pro-inflammatory transcription factors such as Nf-κB. Important examples include immunosuppressants such as different corticosteroids, vitamin D₃, rapamycin and others. The quality of TolDCs induced by different approaches is becoming a vital issue and recent evidence suggests substantial heterogeneity between variously-generated TolDCs as evidenced by their transcriptomic profile and function. The possibility of various "flavors" of TolDCs encourages future research in discovery of Tol-DC inducing agents to enrich various ways of DC manipulation. This would enable a broader range of tools to manipulate DC toward specific characteristics desirable in different disease settings. In recent years, several novel small molecules have been identified with the capacity to promote DC tolerogenic characteristics. In this review, we will present and discuss these novel findings and also highlight novel understandings of tolerogenic mechanisms by which DC tolerogenicity is induced by already established agents.

Genetically stable poliovirus vectors activate dendritic cells and prime antitumor CD8 T cell immunity

Viruses naturally engage innate immunity, induce antigen presentation, and mediate CD8 T cell priming against foreign antigens. Polioviruses can provide a context optimal for generating antigen-specific CD8 T cells, as they have natural tropism for dendritic cells, preeminent inducers of CD8 T cell immunity; elicit Th1-promoting inflammation; and lack interference with innate or adaptive immunity. However, notorious genetic instability and underlying neuropathogenicity has hampered poliovirus-based vector applications. Here we devised a strategy based on the polio:rhinovirus chimera PVSRIPO, devoid of viral neuropathogenicity after intracerebral inoculation in human subjects, for stable expression of exogenous antigens. PVSRIPO vectors infect, activate, and induce epitope presentation in DCs in vitro; they recruit and activate DCs with Th1-dominant cytokine profiles at the injection site in vivo. They efficiently prime tumor antigen-specific CD8 T cells in vivo, induce CD8 T cell migration to the tumor site, delay tumor growth and enhance survival in murine tumor models.

Experimental PVSRIPO oncolytic virus therapy of glioblastoma has shown long-term efficacy in a subset of patients. Here the authors engineer the virus to enable incorporation of tumor-specific antigens, and show proof-of-principle evidence that this modification increases anti-tumor immunity and extends survival in mice.

Annexin-coated particles induce antigen-specific immunosuppression

Apoptotic cells mediate the development of tolerogenic dendritic cells (DC) and thus facilitate induction and maintenance of peripheral tolerance. Following the identification of the evolutionary conserved annexin core domain (Anx) as a specific signal on apoptotic cells which antagonises Toll-like receptor (TLR) signalling, we examined whether the tolerogenic capacity of Anx can be exploited to downregulate antigen-specific immune responses. The treatment of bone marrow-derived dendritic cells (BMDC) with particles harbouring Anx as well as the model antigen ovalbumin (OVA) attenuated the response of OVA-specific OT-II T cells. The co-culture of Anx-particle-treated DC and T cells resulted in an anergy-like phenotype characterized by reduced proliferation and cytokine secretion. Here we demonstrate that the anti-inflammatory effects of Anx which are mediated through DC can be used as a tool to generate a particle-based antigen delivery system that promotes antigen-specific immunosuppression. Such Anx-particles may be a new therapeutic approach for the treatment of autoimmune diseases.

Living on the Edge: Efferocytosis at the Interface of Homeostasis and Pathology

Nearly every tissue in the body undergoes routine turnover of cells as part of normal healthy living. The majority of these cells undergoing turnover die via apoptosis, and then are rapidly removed by phagocytes by the process of efferocytosis that is anti-inflammatory. However, a number of pathologies have recently been linked to defective clearance of apoptotic cells. Perturbed clearance arises for many reasons, including overwhelming of the clearance machinery, disruptions at different stages of efferocytosis, and responses of phagocytes during efferocytosis, all of which can alter the homeostatic tissue environment. This review covers linkages of molecules involved in the different phases of efferocytosis to disease pathologies that can arise due to their loss or altered function.

The Role of Tumor-Derived Vesicles in the Regulation of Antitumor Immunity

In this article, we present a comprehensive, updated, and elucidative review of the current knowledge on the function played by tumor-derived vesicles (TDVs) in the crosstalk between tumor and immune cells. Characterization of the structure, biogenesis, and the major functions of TDVs is reported. The review focuses on particular ways of suppression or activation of CD4+/CD8+ T cells by tumor-derived vesicles. Tumor-derived vesicles play an important role in the suppression of antitumor immunity. During the last 15 years, vesicle research has elucidated and improved our knowledge about the role of the vesicles in intercellular communication. Nevertheless, there are still blinds spots concerning vesicle heterogeneity and isolation methods, their uptake by target cells, and the role of mRNA in T-cell transformation or suppression. Along with the substantial progress in understanding of the role of tumor-derived vesicles in intercellular communication, novel antitumor therapy strategies based on vesicle inhibition in a tumor microenvironment are likely to appear very soon.

A Mathematical Model for DC Vaccine Treatment of Type I Diabetes

Type I diabetes (T1D) is an autoimmune disease that can be managed, but for which there is currently no cure. Recent discoveries, particularly in mouse models, indicate that targeted modulation of the immune response has the potential to move an individual from a diabetic to a long-term, if not permanent, healthy state. In this paper we develop a single compartment mathematical model that captures the dynamics of dendritic cells (DC and tDC), T cells (effector and regulatory), and macrophages in the development of type I diabetes. The model supports the hypothesis that differences in macrophage clearance rates play a significant role in determining whether or not an individual is likely to become diabetic subsequent to a significant immune challenge. With this model we are able to explore the effects of strengthening the anti-inflammatory component of the immune system in a vulnerable individual. Simulations indicate that there are windows of opportunity in which treatment intervention is more likely to be beneficial in protecting an individual from entering a diabetic state. This model framework can be used as a foundation for modeling future T1D treatments as they are developed.

Therapeutic effects of curcumin on sepsis and mechanisms of action: A systematic review of preclinical studies

Sepsis is a complex disease that begins with an infectious disorder and causes excessive immune responses. Curcumin is considered as an active component of turmeric that can improve the condition in sepsis due to its anti-inflammatory and antioxidant properties. PubMed, Embase, Google Scholar, Web of Science, and Scopus databases were searched. Searching was not limited to a specific publication period. Only English-language original articles, which had examined the effect of curcumin on sepsis, were included. At first, 1,098 articles were totally found, and 209 articles were selected after excluding duplicated data; 46 articles were remained due to the curcumin effects on sepsis. These included 23 in vitro studies and 23 animal studies. Our results showed that curcumin and various analogs of curcumin can have an inhibitory effect on sepsis-induced complications. Curcumin has the ability to inhibit the inflammatory, oxidative coagulation factors, and regulation of immune responses in sepsis. Despite the promising evidence of the therapeutic effects of curcumin on the sepsis complication, further studies seem necessary to investigate its effect and possible mechanisms of action in human studies.

A Model for Apoptotic-Cell-Mediated Adaptive Immune Evasion via CD80-CTLA-4 Signaling

Apoptotic cells carry a plethora of self-antigens but they suppress eliciting of innate and adaptive immune responses to them. How apoptotic cells evade and subvert adaptive immune responses has been elusive. Here, we propose a novel model to understand how apoptotic cells regulate T cell activation in different contexts, leading mostly to tolerogenic responses, mainly via taking control of the CD80-CTLA-4 coinhibitory signal delivered to T cells. This model may facilitate understanding of the molecular mechanisms of autoimmune diseases associated with dysregulation of apoptosis or apoptotic cell clearance, and it highlights potential therapeutic targets or strategies for treatment of multiple immunological disorders.

mTOR Inhibitors Can Enhance the Anti-Tumor Effects of DNA Vaccines through Modulating Dendritic Cell Function in the Tumor Microenvironment

The life span of dendritic cells (DCs) can become short following induced activation, which is associated with metabolic transition due to the regulation of mechanistic target of rapamycin (mTOR). The purpose of this study was to investigate the potential of inhibiting mTOR to modulate DC functions for elevating the anti-tumor effects of DNA vaccines. Therefore, the influences of various inhibitors of mTOR (mTORi) on the expressions of DC maturation markers, the abilities of antigen presenting and processing of BMM-derived DCs and the tumor killing effects of E7-specific CD8⁺ T lymphocytes activated by BMM-derived DCs were in vitro examined. The anti-tumor effects of connective tissue growth factor (CTGF)/E7 DNA vaccine and/or mTORi were also in vivo analyzed. In our study, suppressive effects of mTORi on the DC maturation markers expressed on BMMCs could be reversed. The mTORi-treated mature BMM-derived DCs tended to be non-apoptotic. These mTORi-treated BMM-derived DCs could have better antigen presenting and processing abilities. The E7-specific cytotoxic CD8+ T lymphocytes could have more potent tumoricidal activity following activation of mTORi-treated BMM-derived DCs. For tumor-bearing mice, those treated with CTGF/E7 DNA vaccine and mTORi indeed can have higher percentages of mature DCs in the TME, better disease control and longer survivals. Consequently, application of mTORi can be a pharmacological approach for temporally increasing life span, antigen presenting and antigen processing of DCs to strengthen the therapeutic outcome of cancer immunotherapy.

Role of Exosomes in the Regulation of T-cell Mediated Immune Responses and in Autoimmune Disease

: T-cell mediated immune responses should be regulated to avoid the development of autoimmune or chronic inflammatory diseases. Several mechanisms have been described to regulate this process, namely death of overactivated T cells by cytokine deprivation, suppression by T regulatory cells (Treg), induction of expression of immune checkpoint molecules such as CTLA-4 and PD-1, or activation-induced cell death (AICD). In addition, activated T cells release membrane microvesicles called exosomes during these regulatory processes. In this review, we revise the role of exosome secretion in the different pathways of immune regulation described to date and its importance in the prevention or development of autoimmune disease. The expression of membrane-bound death ligands on the surface of exosomes during AICD or the more recently described transfer of miRNA or even DNA inside T-cell exosomes is a molecular mechanism that will be analyzed.

Tocopherol Emulsions as Functional Autoantigen Delivery Vehicles Evoke Therapeutic Efficacy in Experimental Autoimmune Encephalomyelitis

Contemporary approaches to treating autoimmune diseases like multiple sclerosis broadly modulate the immune system and leave patients susceptible to severe adverse effects. Antigen-specific immunotherapies (ASIT) offer a unique opportunity to selectively suppress autoreactive cell populations but have suffered from marginal efficacy even when employing traditional adjuvants to improve delivery. The development of immunologically active antigen delivery vehicles could potentially increase the clinical success of antigen-specific immunotherapies. An emulsion of the antioxidant tocopherol delivering an epitope of proteolipid protein autoantigen (PLP139-151) yielded significant efficacy in mice with experimental autoimmune encephalomyelitis (EAE). In vitro studies indicated tocopherol emulsions reduced oxidative stress in antigen-presenting cells. Ex vivo analysis revealed that tocopherol emulsions shifted cytokine responses in EAE splenocytes. In addition, IgG responses against PLP139-151 were increased in mice treated with tocopherol emulsions delivering the antigen, suggesting a possible skew in immunity. Overall, tocopherol emulsions provide a functional delivery vehicle for ASIT capable of ameliorating autoimmunity in a murine model.