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• Release of Tumor-derived Exosomes (TDEs) is involved in intercellular information exchange. • Tumor-derived Exosomes (TDEs) can negatively regulate the tumor microenvironment. • Tumor-derived Exosomes (TDEs) inhibit peritumour immune cells and create an immunosuppressive environment. Tumor-derived exosomes (TDEs), as topologies of tumor cells, not only carry biological information from the mother, but also act as messengers for cellular communication. It has been demonstrated that TDEs play a key role in inducing an immunosuppressive tumor microenvironment (TME). They can reprogram immune cells indirectly or directly by delivering inhibitory proteins, cytokines, RNA and other substances. They not only inhibit the maturation and function of dendritic cells (DCs) and natural killer (NK) cells, but also remodel M2 macrophages and inhibit T cell infiltration to promote immunosuppression and create a favorable ecological niche for tumor growth, invasion and metastasis. Based on the specificity of TDEs, targeting TDEs has become a new strategy to monitor tumor progression and enhance treatment efficacy. This paper reviews the intricate molecular mechanisms underlying the immunosuppressive effects induced by TDEs to establish a theoretical foundation for cancer therapy. Additionally, the challenges of TDEs as a novel approach to tumor treatment are discussed. [ABSTRACT FROM AUTHOR]

In a recent paper, Schriek et al. show that, in a complement-dependent reaction, marginal zone B cells (MZBs) steal MHC class II (MHCII) from dendritic cells (DCs). Activation of T cells by stolen MHCII complexes potentially allows MZBs to augment or regulate T cell activation in ways that are distinct from DCs. [ABSTRACT FROM AUTHOR]

This article presents abstracts for various research papers to be presented in the 27th Annual Meeting of the European Society for Dermatological Research. These research papers pertain to subjects like proinflammatory cytokines and prostaglandins' inducing maturation of potent immunostiumlatory dendritic cells, mediators that mobilize langerhans cells, antigens for the activation of T lymphocytes by skin dendritic cells and vaccination of melanoma patients with peptide-pulsed dendritic cells.

Created with BioRender.com [Display omitted] Cancer immunity is dependent on dynamic interactions between T cells and dendritic cells (DCs). Polymer-based nanoparticles target DC receptors to improve anticancer immune responses. In this paper, DC surface receptors and their specific coupling natural ligands and antibodies are reviewed and compared. Moreover, reaction mechanisms are described, and the synergistic effects of immune adjuvants are demonstrated. Also, extracellular-targeting antigen-delivery strategies and intracellular stimulus responses are reviewed to promote the rational design of polymer delivery systems. [ABSTRACT FROM AUTHOR]

• We systematically and in detail summarize the classification and biological characteristics of DC, as well as its development process. We focus on and deeply understand the role of DC in regulating the pathogenesis of different allergic diseases. • We demonstrate for the frist time the role of dendritic cells in various allergic diseases including AR, AA, AD, and FA. • Based on inflammatory response and immune regulation, a better understanding of the role of DC in immunomodulation and Th2 immune response can guide the development of new therapeutic targets for various allergic diseases and provide new ideas for the treatment of patients with allergic diseases. Allergic diseases are important diseases that affect many patients worldwide. Over the past few decades, the incidence of allergic diseases has increased significantly due to social development and increased environmental degradation, which has placed a huge economic burden on public health and even led to an increase in mortality. Substantial progress has been made in the understanding of the mechanisms of allergic diseases, and past studies have shown that the occurrence and development of allergic diseases are closely related to changes in the state of the immune system. With the study and in-depth understanding of innate immune lymphocytes, researchers have gradually discovered that dendritic cells (DC) play an important role in many allergic diseases. DC are the body's main antigen-presenting cells, which ingest, process, and hand allergens, and then secrete chemokines such as chemokine ligands 17(CCL17), CCL22, and upregulate their own surface co-stimulating molecules. Then DC present the antigen peptide to the initial T cells and further differentiate them into helper T cells 2(Th2). As an important part of humoral immunity, Th2 participates in the regulation of type 2 immune response through the secretion of cytokines such as interleukin 4(IL-4), IL-5, and IL-13 and plays a leading role. However, our current research on DC is limited and its status in allergic diseases is unclear.Among them, allergic rhinitis, allergic asthma, atopic dermatitis, and food allergy are DC-mediated Th2 immune-related factor disorder-related allergic diseases, and some progress has been made in recent years in the study of the pathogenesis of these diseases. This paper outlines the common phenotypes and activation pathways of DC in different allergic diseases as well as potential research directions to improve the understanding of its immunomodulatory role in different allergic diseases and ultimately find new ways to treat these diseases. [ABSTRACT FROM AUTHOR]

While the cytoskeletal protein talin binds to the β-chain of LFA-1, the immune cell adaptor SKAP1 (SKAP-55) binds to the α-chain of the same integrin via RapL. Whereas calpain protease cleavage of talin is important for LFA-1 activation, it has been unclear whether SKAP1 can alter the function of talin or its associated adaptor RIAM in T-cells. In this paper, we report that Skap1−/− T-cells showed a reduction in the translocation of talin and RIAM to the contact interface of T-cells with antigenic beads or dendritic cells (DCs) presenting OVA peptide to OT-1 T-cells. In addition, Skap1 − / − T-cells show an altered pattern of talin cleavage, while the expression of a cleavage resistant form of talin (L432G) restored the impaired adhesion of OT1 transgenic Skap1 − / − T-cells with DCs. SKAP1 therefore can affect the function of talin in T-cells needed for optimal T-cell/DC conjugation. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Traditional Chinese herbal medicine (CHM) has a long-history for treatment of various human diseases including tumors, infection, autoimmune diseases in Asian countries, especially in China, Japan, Korea and India. CHM was traditionally used as water extracts and many Chinese herbs were considered to be good for health, which can regulate immune system to protect host from diseases. With the progress of technology, the components of CHM were identified and purified, which included polysaccharides, saponins, phenolic compounds, flavonoids and so on. Recently, accumulating evidence indicates that CHM and its components can regulate immune system through targeting dendritic cells (DCs). We hereby reviewed the immunoregulatory effects of CHM on the maturation, cytokine production and function of DCs. This should help to shed light on the potential mechanism of CHM to improve the usage and clinical efficacy of CHM. Materials and methods Literatures about the effects of CHM on DCs were searched in electronic databases such as Pubmed, Google Scholar and Scopus from 2000 to 2014. ‘CHM’, ‘DC’ or ‘immune’ were used as keywords for the searches. We only reviewed literatures published in English. Results Over 600 publications were found about ‘CHM&immune’ and around 120 literatures about ‘CHM&DC’ were selected and reviewed in this paper. All publications are backed by preclinical or clinical evidences both in vitro and in vivo . Some CHM and its components promote the maturation, pro-inflammatory cytokine production and function of DCs and as the adjuvant enhance immune responses against tumor and infection. In contrast, other CHM and its components suppress the activation status of DCs to induce regulatory T cells, inhibit allergic and inflammatory responses, ameliorate autoimmune diseases, and prolong the allograft survival. A large body of evidence shows that CHM and its components regulate the activation status of DCs through TLRs, NF-κB, MAPK signaling pathways. Conclusion This review provides useful information for understanding the mechanism of CHM on the treatment of diseases, which facilitates to improve the efficacy of CHM. Based on the immunoregulatory effects of CHM on DCs, it indicated that some CHM and its components could be use to develop adjuvant to enhance antigen-specific immune responses or tolerogenic adjuvant to generate antigen-specific immune tolerance. [ABSTRACT FROM AUTHOR]

Abstract: Establishment of a leukemia plasmacytoid dendritic cell line (PMDC05) and intra-lineage transformation from pDCs to mDCs in PMDC05 has been reported. In this paper, we show the applicability of PMDC05 for cellular immunotherapy. By stimulation with LPS, PMDC05 showed enhancement in expression of antigen presentation-associated surface molecules and production of cytokines (IL-12p70 and TNF-α). The antigen presenting ability was markedly increased in PMDC05 stimulated with LPS. By co-culturing of CD8+ T cells with LPS-stimulated and WT1/CMVpp65 peptide-pulsed PMDC05, WT1/CMVpp65 tetramer+ cytotoxic T lymphocytes were efficiently generated. These findings reveal the applicability of PMDC05 in cellular immunotherapy for tumor and severe viral infections. [Copyright &y& Elsevier]

Abstract: The immune system has evolved to coordinate responses against numerous invading pathogens and simultaneously remain silent facing self-antigens and those derived from commensal organisms. But, if both processes are not maintained in strict balance, a potential threat can emerge due to the risk of chronic inflammation and/or autoimmunity development. Therefore, there is a negative immune regulation where tolerogenic dendritic cells (tDCs) participate actively. Under steady-state conditions, tDC are notably involved in the elimination of autoreactive T cells at the thymus, and in the control of T cells specific to self and harmless antigens in the periphery. But in the presence of foreign antigens in an inflammatory milieu, dendritic cells (DCs) mature and induce T cells activation and their migration to B cell areas to assist in antibody production. Additionally, there are other factors such as infections, anti tumoral immune responses, trauma-mediated disruption, etc. that may induce alterations in the balance between tolerogenic and immunogenic functions of DCs and instigate the development of autoimmune diseases (ADs). Therefore, in recent years, DCs have emerged as therapeutic targets to control of ADs. Diverse strategies in vitro and/or in animal models of ADs have explored the tolerogenic functions of DCs and demonstrated their feasibility to prevent or control an autoimmune process, but still leaving a void in their application in clinical assays. The purpose of this paper is to give a general overview of the current literature on the significance of tDCs in tolerance maintenance to self and innocuous antigens, the most relevant alterations involved in the pathophysiology of ADs, the cellular and molecular mechanisms involved in their tolerogenic function and the current strategies used to exploit their tolerogenic potential. [Copyright &y& Elsevier]

Abstract: Multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE) have long been regarded as primarily T helper cell type 1-mediated diseases. However, recent evidence suggests that TH17 cells, a mostly unexplored subset of T helper cells, may be even more pathogenic than TH1 cells. In the EAE model, this cell type is crucial for the recruitment of leukocytes into the CNS and for triggering parenchymal inflammation. In humans, TH17 cells are found in acutely active and on the borders of chronically active lesions. Overall, CD4+ T cells only recognize antigens presented on MHC class II complexes, and these are seldom found in the CNS. MHC class I, in contrast, can be induced on neurons and myelin. This also makes CD8+ T cells promising candidates as effector cell types. Indeed, CD8+ T cells outnumber CD4+ T cells in the lesions of MS patients, and can induce axonal pathology. New data on B cells have likewise stimulated unconventional paths of reasoning about the disease. B cells can contribute to the pathogenesis by secreting autoantibodies and presenting antigens to T cells. By the formation of ectopic B cell aggregates in the CNS, B cell differentiation and response can take place remote from the periphery, thus autonomously fueling pathology. In addition, cells of the innate immune system including macrophages, dendritic cells and mast cells are present in the inflamed CNS. On the one hand, these cells can recognize pathogen-associated molecular patterns via Toll-like receptors (TLRs), generating proinflammatory signals that trigger adaptive immune responses. On the other hand, these cells support the autoimmune process by the secretion of effector molecules such as nitric oxide (NO). Apart from a solely pathogenic autoimmune role, regulatory T cells, NK cells and NKT cells can suppress autoreactive cells. In this paper, we review data on how a complex network of immune mechanisms is involved in the pathogenesis of MS and EAE. We also critically reevaluate the traditional CD4/TH1 paradigm. [Copyright &y& Elsevier]

Cortical F-actin plays important roles during HIV-1 infection. A recent paper in Cell highlights the involvement of F-actin in enhancing dendritic cell (DC)-mediated HIV-1 infection of T cells. Such a critical mechanism of HIV-1 trans -enhancement between human DCs and T cells had not been analyzed in molecular detail before this work. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) play a pivotal role in initiating antigen-specific tumor immunity. However, the abnormal function of DCs owing to the immunosuppressive tumor microenvironment (TME) and the insufficient number of tumor infiltrating DCs could promote immune tolerance and tumor immune escape. Thus, there is great potential to employ DCs to induce efficient antitumor immunity. In this paper, we developed intelligent DCs (iDCs), which consist of nanoparticles loaded with photothermal agents (IR-797) and coated with a mature DC membrane. The DC cell membrane on the surface of iDCs preserves the ability to present antigens and prime T cells. The iDCs can also enter the lymph node and stimulate T cells. The activated T cells reduced the expression of heat shock proteins (HSPs) in tumor cells, rendering them more sensitive to heat stress. Subsequently, we used mild photothermal therapy (42–45 °C) to induce immunogenic cell death and contribute to a synergistic antitumor effect. iDCs as a refined and precise system in combination with DC-based immunotherapy and thermal therapy can be stored long-term and on a large scale, so they can be applied in many patients. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the histopathological features and cellular distribution of T lymphocytes (CD3), B cells (CD79), follicular dendritic cells (FDC) and macrophages (alpha-1-antitrypsin, lysozyme) in lymphoid aggregates (Kisselev nodules) found in the lung, kidney and liver of wild boar (Sus scrofa L.). The distribution of immunoreactive cells, tested for antibodies, was similar to that found in the cortex of lymph nodes: lymphoid follicles with germinal centers mainly consisting of CD79+ B cells with sparse interfollicular tissue (CD3+ T lymphocytes). This finding and the association of these structures with helminthic infections suggests that local humoral immunity is central to the organism’s response to parasitic challenge. The presence of follicular dendritic cells confirms the high degree of organization of these lymphoid-like structures. The role of other pathogenic factors and the induction of chronic inflammatory reaction in these ectopic lymphoid sites is also discussed. [Copyright &y& Elsevier]

Dendritic cells (DCs) are recognized as the sole professional antigen-presenting cells capable of priming naive T cells of the helper and cytotoxic phenotypes. This property is presently exploited with success in vaccinal strategies against pathogens or tumor cells that otherwise escape immune recognition, but the repeated infusions of ex vivo expanded and sensitized DCs are usually required to achieve protection. In this paper, we demonstrate that liposomal antigens can efficiently relay and propagate the action of DCs, inducing a strong long-term response against their associated antigen. Their effect is mainly achieved by improving the ex vivo loading of DCs and by efficiently channeling the activation stimulus into the induction of effector function. This is demonstrated by the sustained immunoglobulin production as well as by the sustained lymphoproliferation and the increased cytokine secretion that can be achieved upon restimulation of DC-primed immune cells with limited amount of liposomal antigenic material. Being well-tolerated and easily prepared, liposomal antigens could therefore be expected to significantly contribute to the efficiency and to a more general utilization of the highly promising but rather cumbersome DC-based immunotherapies. [ABSTRACT FROM AUTHOR]

The mechanisms through which tumor antigen-specific T cells are elicited in natural or chemotherapy-induced immunosurveillance have been elusive. In this issue of Cancer Cell , two papers by Broz and colleagues and Ruffell and colleagues delineate an important role for a specific dendritic cell subset characterized by CD103 expression, dependence on transcription factors Batf3 and Irf8, and interleukin-12 production. [ABSTRACT FROM AUTHOR]

Epidermal Langerhans cells are dendritic bone marrow-derived cells which synthesize and express Ia antigens. During the past decade, in vitro studies have demonstrated that they play a critical role in the induction of many types of T-cell responses. Specifically, Langerhans cells are effective antigen-presenting cells in allogeneic and antigen specific proliferative and cytotoxic T-cell responses. This paper reviews these functions and suggests areas of future investigations into the mechanisms involved in T-cell activation by Langerhans cells. [ABSTRACT FROM AUTHOR]