Dendritic cell lineage, plasticity and cross-regulation

Dendritic Cells: A Bridge between Tolerance Induction and Cancer Development in Transplantation Setting

Dendritic cells (DCs) are a heterogeneous group of antigen-presenting cells crucial for fostering allograft tolerance while simultaneously supporting host defense against infections and cancer. Within the tumor microenvironment, DCs can either mount an immune response against cancer cells or foster immunotolerance, presenting a dual role. In immunocompromised individuals, posttransplant malignancies pose a significant health concern, with DCs serving as vital players in immune responses against cancer cells. Both recipient- and donor-derived DCs play a critical role in the rejection process, infiltrating the transplanted organ and sustaining T-cell responses. The use of immunosuppressive drugs represents the predominant approach to control this immunological barrier in transplanted organs. Evidence has shed light on the immunopharmacology of these drugs and novel strategies for manipulating DCs to promote allograft survival. Therefore, comprehending the mechanisms underlying this intricate microenvironment and the effects of immunosuppressive therapy on DCs is crucial for developing targeted therapies to reduce graft failure rates. This review will delve into the fundamental immunobiology of DCs and provide a detailed exploration of their clinical significance concerning alloimmune responses and posttransplant malignancies.

Dendritic Cells in Cancer Immunology and Immunotherapy

Cancer immunotherapy modulates the immune system, overcomes immune escape and stimulates immune defenses against tumors. Dendritic cells (DCs) are professional promoters of immune responses against tumor antigens with the outstanding ability to coordinate the innate and adaptive immune systems. Evidence suggests that there is a decrease in both the number and function of DCs in cancer patients. Therefore, they represent a strong scaffold for therapeutic interventions. DC vaccination (DCV) is safe, and the antitumoral responses induced are well established in solid tumors. Although the addition of checkpoint inhibitors (CPIs) to chemotherapy has provided new options in the treatment of cancer, they have shown no clinical benefit in immune desert tumors or in those tumors with dysfunctional or exhausted T-cells. In this way, DC-based therapy has demonstrated the ability to modify the tumor microenvironment for immune enriched tumors and to potentiate systemic host immune responses as an active approach to treating cancer patients. Application of DCV in cancer seeks to obtain long-term antitumor responses through an improved T-cell priming by enhancing previous or generating de novo immune responses. To date, DCV has induced immune responses in the peripheral blood of patients without a significant clinical impact on outcome. Thus, improvements in vaccines formulations, selection of patients based on biomarkers and combinations with other antitumoral therapies are needed to enhance patient survival. In this work, we review the role of DCV in different solid tumors with their strengths and weaknesses, and we finally mention new trends to improve the efficacy of this immune strategy.

Unveiling the immune symphony: decoding colorectal cancer metastasis through immune interactions

Colorectal cancer (CRC), known for its high metastatic potential, remains a leading cause of cancer-related death. This review emphasizes the critical role of immune responses in CRC metastasis, focusing on the interaction between immune cells and tumor microenvironment. We explore how immune cells, through cytokines, chemokines, and growth factors, contribute to the CRC metastasis cascade, underlining the tumor microenvironment's role in shaping immune responses. The review addresses CRC's immune evasion tactics, especially the upregulation of checkpoint inhibitors like PD-1 and CTLA-4, highlighting their potential as therapeutic targets. We also examine advanced immunotherapies, including checkpoint inhibitors and immune cell transplantation, to modify immune responses and enhance treatment outcomes in CRC metastasis. Overall, our analysis offers insights into the interplay between immune molecules and the tumor environment, crucial for developing new treatments to control CRC metastasis and improve patient prognosis, with a specific focus on overcoming immune evasion, a key aspect of this special issue.

ICAM2 is related to good prognosis in dendritic cell immunotherapy for cancer

Objective: To evaluate the behavior of adhesion molecules ICAM-1 and ICAM-2 in dendritic cell (DC) immunotherapy. Materials & methods: 88 female Balb/c mice were divided into experimental groups. Tumors and lymph nodes were evaluated 7 and 14 days after immunotherapy. Results: Higher mean fluorescence intensity of ICAM-1 in the lymph nodes and tumors in the tumor group at 14 days was observed. Higher mean fluorescence intensity of ICAM-2 in the tumor DC vaccine group was observed after 14 days. A positive correlation was observed in the lymph nodes with ICAM-1 against tumoral volume in the tumor group. A negative correlation was found between ICAM-2 and tumoral volume in the lymph nodes of the tumor group. Conclusion: An increase in ICAM-2 in tumor DC vaccine and a decrease in ICAM-1 suggests the DC vaccine positively influences the immune system and that ICAM-2 could be a marker of good prognosis.

Mechanoregulatory Cholesterol Oxidase-Functionalized Nanoscale Metal-Organic Framework Stimulates Pyroptosis and Reinvigorates T Cells

Cancer cells alter mechanical tension in their cell membranes. New interventions to regulate cell membrane tension present a potential strategy for cancer therapy. Herein, the increase of cell membrane tension by cholesterol oxidase (COD) via cholesterol depletion in vitro and the design of a COD-functionalized nanoscale metal-organic framework, Hf-TBP/COD, for cholesterol depletion and mechanoregulation of tumors in vivo, are reported. COD is found to deplete cholesterol and disrupt the mechanical properties of lipid bilayers, leading to decreased cell proliferation, migration, and tolerance to oxidative stress. Hf-TBP/COD increases mechanical tension of plasma membranes and osmotic fragility of cancer cells, which induces influx of calcium ions, inhibits cell migration, increases rupturing propensity for effective caspase-1 mediated pyroptosis, and decreases tolerance to oxidative stress. In the tumor microenvironment, Hf-TBP/COD downregulates multiple immunosuppressive checkpoints to reinvigorate T cells and enhance T cell infiltration. Compared to Hf-TBP, Hf-TBP/COD improves anti-tumor immune response and tumor growth inhibition from 54.3% and 79.8% to 91.7% and 95% in a subcutaneous triple-negative breast cancer model and a colon cancer model, respectively.

Polysaccharides and Bioactive Phenolics from Aconitum septentrionale Roots

Aconitum septentrionale is known to contain toxic diterpene alkaloids, while other bioactive compounds in the plant remain unclear. The aim of this study was to explore the phenolic compounds and polysaccharides from the water extract of A. septentrionale roots. Fifteen phenolic compounds were isolated and identified by NMR and MS, including fourteen known and one new dianthramide glucoside (2-[[2-(β-D-glucopyranosyloxy)-5-hydroxybenzoyl]amino]-4,5-dihydroxybenzoic acid methyl ester, 14). One neutral (complex of glucans with minor amounts of mannans) and two acidic polysaccharide fractions (complexes of pectic polysaccharides and glucans) were also obtained. Hydroxytyrosol (1), hydroxytyrosol-1-O-β-glucoside (2) and bracteanolide A (7) inhibited the release of nitric oxide by dendritic cells. Magnoflorine (8) and 2-[[2-(β-D-glucopyranosyloxy)-5-hydroxybenzoyl]amino]-5-hydroxybenzoic acid methyl ester (12) inhibited 15-lipoxygenase, and bracteanolide A (7) was a moderate inhibitor of xanthine oxidase. This study is the first to describe the diversity of phenolics and polysaccharides from A. septentrionale and their anti-inflammatory and anti-oxidant activities.

Mast Cell and Innate Immune Cell Communication in Cholestatic Liver Disease

Mast cells (MCs) contribute to the pathogenesis of cholestatic liver diseases (primary sclerosing cholangitis [PSC] and primary biliary cholangitis [PBC]). PSC and PBC are immune-mediated, chronic inflammatory diseases, characterized by bile duct inflammation and stricturing, advancing to hepatobiliary cirrhosis. MCs are tissue resident immune cells that may promote hepatic injury, inflammation, and fibrosis formation by either direct or indirect interactions with other innate immune cells (neutrophils, macrophages/Kupffer cells, dendritic cells, natural killer, and innate lymphoid cells). The activation of these innate immune cells, usually through the degranulation of MCs, promotes antigen uptake and presentation to adaptive immune cells, exacerbating liver injury. In conclusion, dysregulation of MC-innate immune cell communications during liver injury and inflammation can lead to chronic liver injury and cancer.

The Phylogeny, Ontogeny, and Organ-specific Differentiation of Macrophages in the Developing Intestine

Macrophages are large highly motile phagocytic leukocytes that appear early during embryonic development and have been conserved during evolution. The developmental roles of macrophages were first described nearly a century ago, at about the time these cells were being identified as central effectors in phagocytosis and elimination of microbes. Since then, we have made considerable progress in understanding the development of various subsets of macrophages and the diverse roles these cells play in both physiology and disease. This article reviews the phylogeny and the ontogeny of macrophages with a particular focus on the gastrointestinal tract, and the role of these mucosal macrophages in immune surveillance, innate immunity, homeostasis, tissue remodeling, angiogenesis, and repair of damaged tissues. We also discuss the importance of these macrophages in the inflammatory changes in neonatal necrotizing enterocolitis (NEC). This article presents a combination of our own peer-reviewed clinical and preclinical studies, with an extensive review of the literature using the databases PubMed, EMBASE, and Scopus.

Transcriptional programming of immunoregulatory responses in human Langerhans cells

Human epidermal Langerhans cells (LCs) maintain immune homeostasis in the skin. To examine transcriptional programming of human primary LCs during homeostasis, we performed scRNA-seq analysis of LCs before and after migration from the epidermis, coupled with functional assessment of their regulatory T cell priming capabilities. The analysis revealed that steady-state LCs exist in a continuum of maturation states and upregulate antigen presentation genes along with an immunoregulatory module including the genes IDO1, LGALS1, LAMTOR1, IL4I, upon their migration. The migration-induced transition in genomic state is accompanied by the ability of LCs to more efficiently prime regulatory T cell responses in co-culture assays. Computational analyses of the scRNAseq datasets using SCENIC and Partial Information Decomposition in Context identified a set of migration-induced transcription factors including IRF4, KLF6 and RelB as key nodes within a immunoregulatory gene regulatory network. These findings support a model in which efficient priming of immunoregulatory responses by LCs is dependent on coordinated upregulation of a migration-coupled maturation program with a immunoregulation-promoting genomic module.

Mechanobiology of immune cells: Messengers, receivers and followers in leishmaniasis aiding synthetic devices

Cytokines are influential molecules which can direct cells behavior. In this review, cytokines are referred as messengers, immune cells which respond to cytokine stimulus are referred as receivers and the immune cells which gets modulated due to their plasticity induced by infectious pathogen leishmania, are referred as followers. The advantage of plasticity of cells is taken by the parasite to switch them from parasite eliminating form to parasite survival favoring form through a process called as reciprocity which is undergone by cytokines, wherein pro-inflammatory to anti-inflammatory switch occur rendering immune cell population to switch their phenotype. Detailed study of this switch can help in identification of important targets which can help in restoring the phenotype to parasite eliminating form and this can be done through synthetic circuit, finding its wider applicability in therapeutics.

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Cytokines as messengers for governing reciprocity in infection.

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Leishmania induces reciprocity modulating the immune cells plasticity.

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Reciprocity of cytokines identifies important target for therapeutics.

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Therapeutic targets aiding the design of synthetic devices to combat infection.

Sterilizing Immunity against COVID-19: Developing Helper T cells I and II activating vaccines is imperative

Six months after the publication of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) sequence, a record number of vaccine candidates were listed, and quite a number of them have since been approved for emergency use against the novel coronavirus disease 2019 (COVID-19). This unprecedented pharmaceutical feat did not only show commitment, creativity and collaboration of the scientific community, but also provided a swift solution that prevented global healthcare system breakdown. Notwithstanding, the available data show that most of the approved COVID-19 vaccines protect only a proportion of recipients against severe disease but do not prevent clinical manifestation of COVID-19. There is therefore the need to probe further to establish whether these vaccines can induce sterilizing immunity, otherwise, COVID-19 vaccination would have to become a regular phenomenon. The emergence of SARS-CoV-2 variants could further affect the capability of the available COVID-19 vaccines to prevent infection and protect recipients from a severe form of the disease. These notwithstanding, data about which vaccine(s), if any, can confer sterilizing immunity are unavailable. Here, we discuss the immune responses to viral infection with emphasis on COVID-19, and the specific adaptive immune response to SARS-CoV-2 and how it can be harnessed to develop COVID-19 vaccines capable of conferring sterilizing immunity. We further propose factors that could be considered in the development of COVID-19 vaccines capable of stimulating sterilizing immunity. Also, an old, but effective vaccine development technology that can be applied in the development of COVID-19 vaccines with sterilizing immunity potential is reviewed.

The Liver and the Hepatic Immune Response in Trypanosoma cruzi Infection, a Historical and Updated View

Chagas disease was described more than a century ago and, despite great efforts to understand the underlying mechanisms that lead to cardiac and digestive manifestations in chronic patients, much remains to be clarified. The disease is found beyond Latin America, including Japan, the USA, France, Spain, and Australia, and is caused by the protozoan Trypanosoma cruzi. Dr. Carlos Chagas described Chagas disease in 1909 in Brazil, and hepatomegaly was among the clinical signs observed. Currently, hepatomegaly is cited in most papers published which either study acutely infected patients or experimental models, and we know that the parasite can infect multiple cell types in the liver, especially Kupffer cells and dendritic cells. Moreover, liver damage is more pronounced in cases of oral infection, which is mainly found in the Amazon region. However, the importance of liver involvement, including the hepatic immune response, in disease progression does not receive much attention. In this review, we present the very first paper published approaching the liver's participation in the infection, as well as subsequent papers published in the last century, up to and including our recently published results. We propose that, after infection, activated peripheral T lymphocytes reach the liver and induce a shift to a pro-inflammatory ambient environment. Thus, there is an immunological integration and cooperation between peripheral and hepatic immunity, contributing to disease control.

Complement and Chlamydia psittaci: Early Complement-Dependent Events Are Important for DC Migration and Protection During Mouse Lung Infection

The zoonotic intracellular bacterium Chlamydia psittaci causes life-threatening pneumonia in humans. During mouse lung infection, complement factor C3 and the anaphylatoxin C3a augment protection against C. psittaci by a so far unknown mechanism. To clarify how complement contributes to the early, innate and the late, specific immune response and resulting protection, this study addresses the amount of C3, the timing when its presence is required as well as the anaphylatoxin receptor(s) mediating its effects and the complement-dependent migration of dendritic cells. Challenge experiments with C. psittaci on various complement KO mice were combined with transient decomplementation by pharmacological treatment, as well as the analysis of in vivo dendritic cells migration. Our findings reveal that a plasma concentration of C3 close to wildtype levels was required to achieve full protection. The diminished levels of C3 of heterozygote C3+/- mice permitted already relative effective protection and improved survival as compared to C3-/- mice, but overall recovery of these animals was delayed. Complement was in particular required during the first days of infection. However, additionally, it seems to support protection at later stages. Migration of CD103+ dendritic cells from the infected lung to the draining lymph node-as prerequisite of antigen presentation-depended on C3 and C3aR and/or C5aR. Our results provide unique mechanistic insight in various aspects of complement-dependent immune responses under almost identical, rather physiological experimental conditions. Our study contributes to an improved understanding of the role of complement, and C3a in particular, in infections by intracellular bacteria.

Dendritic cells in COVID-19 immunopathogenesis: insights for a possible role in determining disease outcome

SARS-CoV-2 is the causative agent of the COVID-19 pandemic. This novel coronavirus emerged in China, quickly spreading to more than 200 countries worldwide. Although most patients are only mildly ill or even asymptomatic, some develop severe pneumonia and become critically ill. One of the biggest unanswered questions is why some develop severe disease, whilst others do not. Insight on the interaction between SARS-CoV-2 and the immune system and the contribution of dysfunctional immune responses to disease progression will be instrumental to the understanding of COVID-19 pathogenesis, risk factors for worst outcome, and rational design of effective therapies and vaccines. In this review we have gathered the knowledge available thus far on the epidemiology of SARS-COV-2 infection, focusing on the susceptibility of older individuals, SARS-CoV-2-host cell interaction during infection and the immune response directed at SARS-CoV-2. Dendritic cells act as crucial messengers linking innate and adaptative immunity against viral infections. Thus, this review also brings a focused discussion on the role of dendritic cells and their immune functions during SARS-CoV-2 infection and how immune evasion strategies of SARS-CoV-2 and advancing age mediate dendritic cell dysfunctions that contribute to COVID-19 pathogenesis and increased susceptibility to worst outcomes. This review brings to light the hypothesis that concomitant occurrence of dendritic cell dysfunction/cytopathic effects induced by SARS-CoV-2 and/or aging may influence disease outcome in the elderly. Lastly, a detailed discussion on the effects and mechanisms of action of drugs currently being tested for COVID-19 on the function of dendritic cells is also provided.

Role of γδ T cells in controlling viral infections with a focus on influenza virus: implications for designing novel therapeutic approaches

BACKGROUND

Influenza virus infection is among the most detrimental threats to the health of humans and some animals, infecting millions of people annually all around the world and in many thousands of cases giving rise to pneumonia and death. All those health crises happen despite previous and recent developments in anti-influenza vaccination, suggesting the need for employing more sophisticated methods to control this malign infection. Main body The innate immunity modules are at the forefront of combating against influenza infection in the respiratory tract, among which, innate T cells, particularly gamma-delta (γδ) T cells, play a critical role in filling the gap needed for adaptive immune cells maturation, linking the innate and adaptive immunity together. Upon infection with influenza virus, production of cytokines and chemokines including CCL3, CCL4, and CCL5 from respiratory epithelium recruits γδ T cells at the site of infection in a CCR5 receptor-dependent fashion. Next, γδ T cells become activated in response to influenza virus infection and produce large amounts of proinflammatory cytokines, especially IL-17A. Regardless of γδ T cells' roles in triggering the adaptive arm of the immune system, they also protect the respiratory epithelium by cytolytic and non-cytolytic antiviral mechanisms, as well as by enhancing neutrophils and natural killer cells recruitment to the infection site.

CONCLUSION

In this review, we explored varied strategies of γδ T cells in defense to influenza virus infection and how they can potentially provide balanced protective immune responses against infected cells. The results may provide a potential window for the incorporation of intact or engineered γδ T cells for developing novel antiviral approaches or for immunotherapeutic purposes.

Galactosylated chitosan-modified ethosomes combined with silk fibroin nanofibers is useful in transcutaneous immunization

Transcutaneous immunization (TCI) has the advantages of avoiding the liver first-pass effect, good compliance and convenient use compared with the traditional oral or injection vaccination. However, the stratum corneum (SC) of the skin is the main obstacle that limits the entry of antigen molecules into the epidermis for activating dendritic cells (DCs). In the present study, the hyaluronic acid (HA) and galactosylated chitosan (GC) modified ethosome (Eth-HA-GC) was prepared through layer-by-layer self-assembly method. Eth-HA-GC has good stability and can be effectively phagocytosed by the bone-marrow-derived DCs (BMDCs) in vitro. The ovalbumin (OVA) loaded Eth-HA-GC (OVA@Eth-HA-GC) can promote BMDCs' expression of CD80, CD86 (DCs maturation-associated marker molecules), TNF-α, IL-2 and IL-6. Subsequently, a novel OVA@Eth-HA-GC-loaded silk fibroin (OVA@Eth-HA-GC/SF) nanofibrous mats were fabricated through green electrospinning. The OVA@Eth-HA-GC/SF mats exhibit good transdermal performance in vitro. Transdermal administration with OVA@Eth-HA-GC/SF mats induced the serum anti-OVA-specific IgG and increased the expression of IFN-γ, IL-2 and IL-6 by spleen cells in vivo. Furthermore, the use of OVA@Eth-HA-GC/SF mats evidently inhibited the growth of EG7 tumor in the murine model. These results demonstrate the OVA@Eth-HA-GC/SF mats can effectively stimulate the immune response to OVA through transdermal administration. In conclusion, the antigens@Eth-HA-GC/SF mats is a promising TCI system.

A Quantitative Multivariate Model of Human Dendritic Cell-T Helper Cell Communication

Cell-cell communication involves a large number of molecular signals that function as words of a complex language whose grammar remains mostly unknown. Here, we describe an integrative approach involving (1) protein-level measurement of multiple communication signals coupled to output responses in receiving cells and (2) mathematical modeling to uncover input-output relationships and interactions between signals. Using human dendritic cell (DC)-T helper (Th) cell communication as a model, we measured 36 DC-derived signals and 17 Th cytokines broadly covering Th diversity in 428 observations. We developed a data-driven, computationally validated model capturing 56 already described and 290 potentially novel mechanisms of Th cell specification. By predicting context-dependent behaviors, we demonstrate a new function for IL-12p70 as an inducer of Th17 in an IL-1 signaling context. This work provides a unique resource to decipher the complex combinatorial rules governing DC-Th cell communication and guide their manipulation for vaccine design and immunotherapies.

Acupoint Catgut Embedding Improves the Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome in Rats

Background

This study investigated the potential therapeutic effects of acupoint catgut embedding (ACE) at ST36 and BL13 on lipopolysaccharide- (LPS-) induced acute respiratory distress syndrome (ARDS) in rats.

Materials and Methods

Male Sprague-Dawley rats were randomized into the normal saline (NS group with a sham procedure), lipopolysaccharide (LPS group with a sham procedure), and LPS plus ACE (LPS+ACE with ACE at bilateral BL13 and ST36 acupoints one day before LPS injection) groups. After intratracheal instillation of normal saline or LPS (0.5 mg/kg), all rats were subjected to mechanical ventilation for 4 h. Their blood gas was analyzed before and after lung injury, and their lung pressure-volumes were measured longitudinally. The levels of TNF-α, IL-6, IL-10, and phosphatidylcholine (PC) and total proteins (TP) in bronchial alveolar lavage fluid (BALF) were assessed. Their wet to dry lung weight ratios, histology, myeloperoxidase (MPO), superoxide dismutase (SOD) activity, and malondialdehyde (MDA) levels were measured. Their lung aquaporin 1 (AQP1) and Occludin protein levels were analyzed.

Results

LPS administration significantly decreased the ratios of PaO₂/FiO₂ and pressure-volumes and induced lung inflammation and injury by increased concentrations of TNF-α, IL-6, IL-10, and TP in BALF and MPO and MDA in the lung but decreased PC in BALF and SOD activity in the lungs. LPS also reduced AQP1 and Occludin protein levels in the lung of rats. In contrast, ACE significantly mitigated the LPS-induced lung injury, inflammation, and oxidative stress and preserved the AQP1 and Occludin contents in the lung of rats.

Conclusions

ACE significantly improved respiratory function by mitigating inflammation and oxidative stress and preserving AQP1 and Occludin expression in the lung in a rat model of LPS-induced ARDS.

Immunoregulatory properties of mesenchymal stem cells: Micro-RNAs

Mesenchymal stem cells (MSCs) are multipotent cells that are excellent candidates for different cellular therapies due to their physiological properties such as immunoregulatory function. whetheare currently utilized for regenerative medication and treatment of a number of inflammatory illnesses given their ability to considerably impact tissue microenvironments via extracellular vesicles or toll-like receptor pathway modulation. MicroRNAs (miRNAs) are small noncoding RNAs that target the messenger RNA and play a critical role in different biological procedures, such as the development and reaction of the immune system. Moreover, miRNAs have recently been revealed to have serious functions in MSCs to regulate immunomodulatory properties. In this review, we study how the miRNAs pathway can modulate the immunoregulatory activity of MSCs by counting their interactions with immune cells and also discuss the possibility of using miRNA-based implications for MSC-based therapies.

Neurokinin-1 Receptor Antagonism Ameliorates Dry Eye Disease by Inhibiting Antigen-Presenting Cell Maturation and T Helper 17 Cell Activation

Neuroinflammation plays an important role in the pathogenesis of ocular surface disease, including dry eye disease (DED), but little is known about the contribution of substance P (SP) to DED. In this study, we investigated the expression of SP at the ocular surface and evaluated its effect on maturation of antigen-presenting cells (APCs), the key cell component involved in the induction of type 17 helper T-cell (Th17) response in DED. The effect of topical blockade of SP signaling was further investigated using neurokinin-1 receptor (NK1R) inhibitors on APC maturation, Th17 cell activation, and disease severity in a mouse model of DED. The results demonstrate that SP is constitutively expressed at the ocular surface, and trigeminal ganglion neurons are the major source of SP in DED. SP derived from trigeminal ganglion enhanced the expression of major histocompatibility complex class II maturation marker by bone marrow-derived dendritic cells, an effect that is abrogated by blockade of SP signaling using NK1R antagonist spantide. Finally, using a well-established murine model of DED, topical treatment of DED mice with NK1R antagonists CP-99,994 and L-733,060 suppressed APC acquisition of major histocompatibility complex class II, reduced Th17 cell activity, and ameliorated DED severity. These findings are of translational value, as they suggest that antagonizing NK1R-mediated SP signaling may be an effective strategy in suppressing Th17-mediated ocular surface disease.

Decellularized Lymph Node Scaffolding as a Carrier for Dendritic Cells to Induce Anti-Tumor Immunity

In recent decades, the decellularized extracellular matrix (ECM) has shown potential as a promising scaffold for tissue regeneration. In this study, an organic acid decellularized lymph node (dLN) was developed as a carrier for dendritic cells (DCs) to induce antitumor immunity. The dLNs were prepared by formic acid, acetic acid, or citric acid treatment. The results showed highly efficient removal of cell debris from the lymph node and great preservation of ECM architecture and biomolecules. In addition, bone marrow dendritic cells (BMDCs) grown preferably inside the dLN displayed the maturation markers CD80, CD86, and major histocompatibility complex (MHC)-II, and they produced high levels of interleukin (IL)-1β, IL-6, and IL-12 cytokines when stimulated with ovalbumin (OVA) and CpG oligodeoxynucleotides (CPG-ODN). In an animal model, the BMDC-dLN completely rejected the E.G7-OVA tumor. Furthermore, the splenocytes from BMDC-dLN-immunized mice produced more interferon gamma, IL-4, IL-6, and IL-2, and they had a higher proliferation rate than other groups when re-stimulated with OVA. Hence, BMDC-dLN could be a promising DC-based scaffold for in vivo delivery to induce potent antitumor immunity.

The Role of Innate Leukocytes during Influenza Virus Infection

Influenza virus infection is a serious threat to humans and animals, with the potential to cause severe pneumonia and death. Annual vaccination strategies are a mainstay to prevent complications related to influenza. However, protection from the emerging subtypes of influenza A viruses (IAV) even in vaccinated individuals is challenging. Innate immune cells are the first cells to respond to IAV infection in the respiratory tract. Virus replication-induced production of cytokines from airway epithelium recruits innate immune cells to the site of infection. These leukocytes, namely, neutrophils, monocytes, macrophages, dendritic cells, eosinophils, natural killer cells, innate lymphoid cells, and γδ T cells, become activated in response to IAV, to contain the virus and protect the airway epithelium while triggering the adaptive arm of the immune system. This review addresses different anti-influenza virus schemes of innate immune cells and how these cells fine-tune the balance between immunoprotection and immunopathology during IAV infection. Detailed understanding on how these innate responders execute anti-influenza activity will help to identify novel therapeutic targets to halt IAV replication and associated immunopathology.

Mst1-Deficiency Induces Hyperactivation of Monocyte-Derived Dendritic Cells via Akt1/c-myc Pathway

Mst1 is a multifunctional serine/threonine kinase that is highly expressed in several immune organs. The role of Mst1 in the activation of dendritic cells (DCs), a key player of adaptive immunity, is poorly understood. In this study, we investigated the role of Mst1 in GM-CSF-induced bone marrow-derived DCs and the underlying mechanisms. Mst1^−/− DCs in response to GM-CSF expressed higher levels of activation/maturation-related cell surface molecules, such as B7 and MHC class II than Mst1^+/+ DCs. Furthermore, the expression of proinflammatory cytokines, such as IL-23, TNF-α, and IL-12p40, was increased in Mst1^−/− DCs, indicating that Mst1-deficiency may induce the hyperactivation of DCs. Additionally, Mst1^−/− DCs exhibited a stronger capacity to activate allogeneic T cells than Mst1^+/+ DCs. Silencing of Mst1 in DCs promoted their hyperactivation, similar to the phenotypes of Mst1^−/− DCs. Mst1^−/− DCs exhibited an increase in Akt1 phosphorylation and c-myc protein levels. In addition, treatment with an Akt1 inhibitor downregulated the protein level of c-myc increased in Mst1-deficient DCs, indicating that Akt1 acts as an upstream inducer of the de novo synthesis of c-myc. Finally, Akt1 and c-myc inhibitors downregulated the increased expression of IL-23p19 observed in Mst1-knockdown DCs. Taken together, these data demonstrate that Mst1 negatively regulates the hyperactivation of DCs through downregulation of the Akt1/c-myc axis in response to GM-CSF, and suggest that Mst1 is one of the endogenous factors that determine the activation status of GM-CSF-stimulated inflammatory DCs.

The Role of Mesenchymal Stem Cells in Atherosclerosis: Prospects for Therapy via the Modulation of Inflammatory Milieu

Atherosclerosis is a chronic, inflammatory disease that mainly affects the arterial intima. The disease is more prevalent in middle-age and older individuals with one or more cardiovascular risk factors, including dyslipidemia, hypertension, diabetes, smoking, obesity, and others. The beginning and development of atherosclerosis has been associated with several immune components, including infiltration of inflammatory cells, monocyte/macrophage-derived foam cells, and inflammatory cytokines and chemokines. Mesenchymal stem cells (MSCs) originate from several tissue sources of the body and have self-renewal and multipotent differentiation characteristics. They also have immunomodulatory and anti-inflammatory properties. Recently, it was shown that MSCs have a regulatory role in plasma lipid levels. In addition, MSCs have shown to have promising potential in terms of treatment strategies for several diseases, including those with an inflammatory component. In this regard, transplantation of MSCs to patients with atherosclerosis has been proposed as a novel strategy in the treatment of this disease. In this review, we summarize the current advancements regarding MSCs for the treatment of atherosclerosis.

Interleukin-36 alpha levels are elevated in the serum and cerebrospinal fluid of patients with neuromyelitis optica spectrum disorder and correlate with disease activity

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory neurological disease characterized by longitudinally extensive transverse myelitis (LETM) and optic neuritis. Interleukin (IL)-36 is a novel cytokine of the IL-1 family that is involved in the development of inflammatory diseases. The aim of this study was to investigate the role of IL-36α in NMOSD. We retrospectively collected 73 patients, who fulfilled the 2015 criteria for NMOSD diagnosis and were admitted to the Department of Neurology of the First Hospital of Jilin University from 2015 to 2016. Fifty age and gender matched patients with non-inflammatory neurological disorders (ONNDs) were collected in the same period and served as controls. Neurological function was evaluated by the expanded disability status scale (EDSS). All participants were assessed for the annual relapse rate (ARR). Blood and cerebrospinal fluid (CSF) samples were obtained and the levels of IL-36α in the serum and CSF were analyzed by enzyme-linked immunosorbent assay (ELISA). IL-36α levels in serum and CSF were found to be significantly increased in patients with NMOSD compared to those in the controls. Furthermore, IL-36α levels in both serum and CSF were positively correlated with the EDSS score. CSF IL-36α levels were positively correlated with CSF leukocyte counts, protein concentration and immunoglobulin IgG. Our results suggest that IL-36α may be a novel biomarker for monitoring disease severity in NMOSD.

Skin sensitization: Uncertainties, challenges, and opportunities for improved risk assessment

At the ESCD congress held in Manchester in 2016, a session was organized to encourage more dialogue between clinicians with expertise in skin sensitization and toxicologists seeking to provide effective risk assessment to prevent human health issues. That session focused on the remaining uncertainties regarding the induction and regulation of skin sensitization in humans, and the opportunities and challenges associated with the refinement and improvement of risk assessment methodologies. This short article, prompted by those discussions, debates what the authors regard as being among the most important and most intriguing uncertainties about skin sensitization and allergic contact dermatitis in humans, and the most significant opportunities for improving risk assessment. The aim has been to provide a basis for mapping out the areas that might benefit from a closer alignment between the relevant clinical community and toxicologists charged with the responsibility of ensuring that skin sensitization risks are understood and managed.

Tolerogenic Dendritic Cells and T-Regulatory Cells at the Clinical Trials Crossroad for the Treatment of Autoimmune Disease; Emphasis on Type 1 Diabetes Therapy

Tolerogenic dendritic cells and T-regulatory cells are two immune cell populations with the potential to prevent the onset of clinical stage type 1 diabetes, and manage the beginning of underlying autoimmunity, at the time-at-onset and onwards. Initial phase I trials demonstrated that the administration of a number of these cell populations, generated ex vivo from peripheral blood leukocytes, was safe. Outcomes of some of these trials also suggested some level of autoimmunity regulation, by the increase in the numbers of regulatory cells at different points in a network of immune regulation in vivo. As these cell populations come to the cusp of pivotal phase II efficacy trials, a number of questions still need to be addressed. At least one mechanism of action needs to be verified as operational, and through this mechanism biomarkers predictive of the underlying autoimmunity need to be identified. Efficacy in the regulation of the underlying autoimmunity also need to be monitored. At the same time, the absence of a common phenotype core among the different dendritic cell and T-regulatory cell populations, that have completed phase I and early phase II trials, necessitates a better understanding of what makes these cells tolerogenic, especially if a uniform phenotypic core cannot be identified. Finally, the inter-relationship of tolerogenic dendritic cells and T-regulatory cells for survival, induction, and maintenance of a tolerogenic state that manages the underlying diabetes autoimmunity, raises the possibility to co-administer, or even to serially-administer tolerogenic dendritic cells together with T-regulatory cells as a cellular co-therapy, enabling the best possible outcome. This is currently a knowledge gap that this review aims to address.

Surface assembly of poly(I:C) on polyethyleneimine-modified gelatin nanoparticles as immunostimulatory carriers for mucosal antigen delivery

The mucosal immune system is the host's first line of defense against invasion by foreign pathogens. Gelatin nanoparticles (GNPs) are suitable carriers for the delivery of antigens via various routes of administration. In the present study, GNPs were modified with polyethyleneimine (PEI), a positively charged polymer. Then, ovalbumin (OVA) and polyinosinic:polycytidylic acid (poly(I:C)), an immunostimulant, were adsorbed onto the surface of the positively charged GNPs. We assessed whether GNPs could act as an effective mucosal vaccine that is capable of inducing both mucosal and systemic immune responses. The results showed that GNPs effectively adsorbed OVA/poly(I:C), facilitated cellular uptake by RAW 264.7 macrophage cells and murine bone marrow-derived dendritic cells (BMDCs) in vitro, and led to increased expression of the maturation markers CD80 and CD86 on BMDCs. Furthermore, GNPs induced increased secretion of proinflammatory cytokines in both RAW 264.7 and BMDCs. C57BL/6 mice that were intranasally twice-immunized with OVA/poly(I:C)-loaded GNPs produced high levels of serum OVA-specific IgG antibodies and secretory IgA in nasal and lung lavage. Spleen cells from immunized mice were collected and re-stimulated with OVA, and results showed significantly augmented production of IFN-γ, IL-4, IL-5, and IL-6 in mice that received OVA/poly(I:C)-loaded GNPs. Moreover, intranasal immunization with OVA/poly(I:C)-loaded GNPs resulted in the inhibition of EG7 tumor growth in C57BL/6 mice. Taken together, these results indicate that nasal administration of OVA/poly(I:C)-loaded GNPs elicited effective mucosal and systemic immune responses, which might be useful for further applications of antigen delivery. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1228-1237, 2019.

Skin and respiratory chemical allergy: confluence and divergence in a hybrid adverse outcome pathway

Sensitisation of the respiratory tract to chemicals resulting in respiratory allergy and allergic asthma is an important occupational health problem, and presents toxicologists with no shortage of challenges. A major issue is that there are no validated or, even widely recognised, methods available for the identification and characterisation of chemical respiratory allergens, or for distinguishing respiratory allergens from contact allergens. The first objective here has been review what is known (and what is not known) of the mechanisms through which chemicals induce sensitisation of the respiratory tract, and to use this information to construct a hybrid Adverse Outcome Pathway (AOP) that combines consideration of both skin and respiratory sensitisation. The intention then has been to use the construction of this hybrid AOP to identify areas of commonality/confluence, and areas of departure/divergence, between skin sensitisation and sensitisation of the respiratory tract. The hybrid AOP not only provides a mechanistic understanding of how the processes of skin and respiratory sensitisation differ, buy also a means of identifying areas of uncertainty about chemical respiratory allergy that benefit from a further investment in research.

Roles of STAT3 in leukemia (Review)

Leukemia is a type of hematopoietic malignancy, and the incidence rate in the United States and European Union increases by an average of 0.6 to 0.7% annually. The incidence rate in China is approximately 5.17/100,000 individuals, and the mortality rate is 3.94/100,000 individuals. Leukemia is the most common tumor affecting children and adults under 35 years of age, and is one of the major diseases leading to the death of adolescents. Signal transducer and activator of transcription 3 (STAT3) is a vital regulatory factor of signal transduction and transcriptional activation, and once activated, the phosphorylated form of STAT3 (p-STAT3) is transferred into the nucleus to regulate the transcription of target genes, and plays important roles in cell proliferation, differentiation, apoptosis and other physiological processes. An increasing number of studies have confirmed that the abnormal activation of STAT3 is involved in the development of tumors. In this review, the roles of STAT3 in the pathogenesis, diagnosis, treatment and prognosis of leukemia are discussed in the aspects of cell proliferation, differentiation and apoptosis, with the aim to further clarify the roles of STAT3 in leukemia, and shed light into possible novel targets and strategies for clinical diagnosis and treatment.

Dysfunction of antigen processing and presentation by dendritic cells in cancer

The ability to mount an effective anti-tumor immune response requires coordinate control of CD4 T cell and CD8 T cell function by antigen presenting cells (APCs). Unfortunately, tumors create an immunosuppressive microenvironment that helps protect tumor cells from immune recognition. In many cases this defect can be traced back to a failure of APCs (most importantly dendritic cells (DCs)) to recognize, process, and present tumor antigens to T cells. In this review, we will summarize work addressing the role of different DC subsets in anti-tumor immunity and the various mechanisms used by tumor cells to suppress the ability of APCs to stimulate potent anti-tumor T cell responses.

Alterations in natural killer and dendritic cell subsets in individuals with HIV-associated neurotuberculosis

One of the commonest HIV-associated opportunistic infections of the central nervous system is neurotuberculosis. Interaction between HIV, Mycobacterium tuberculosis and host immune system in co-infected individuals may result in altered frequencies of immune cells, thereby modulating dissemination and disease progression. We examined the frequencies of natural killer (NK) cell and dendritic cell (DC) subsets in HIV infected individuals with neurotuberculosis (HIVNTB) as compared to individuals with HIV associated systemic TB (HIVSTB), asymptomatic HIV, non-HIV NTB, non-HIV STB, and healthy controls. Peripheral blood mononuclear cells (PBMC) were stained with fluorochrome-conjugated monoclonal antibodies- Lineage cocktail (containing CD3, CD14, CD19, and CD20), HLA-DR, CD16, CD56, CD11c, and CD123, fixed with 2% paraformaldehyde and analyzed on the flow cytometer. The pDCs were significantly reduced in all HIV infected groups, with a marked reduction in HIVNTB cases as compared to healthy controls. While the CD56^- CD16^bt NK cell subset displayed a significant increase in frequency in all three HIV infected groups compared the three HIV negative groups, the CD56^dim CD16^bt subset was significantly lower in frequency in the HIVNTB compared to healthy controls. The decreased frequencies of plasmacytoid DCs and cytotoxic NK cells, which are crucial for innate immune defence against HIV, may result in ineffective virus control and lead to an exacerbated course of disease in HIVNTB individuals.

Diversification of human plasmacytoid predendritic cells in response to a single stimulus

Innate immune cells adjust to microbial and inflammatory stimuli through a process termed environmental plasticity, which links a given individual stimulus to a unique activated state. Here, we report that activation of human plasmacytoid predendritic cells (pDCs) with a single microbial or cytokine stimulus triggers cell diversification into three stable subpopulations (P1-P3). P1-pDCs (PD-L1⁺CD80^-) displayed a plasmacytoid morphology and specialization for type I interferon production. P3-pDCs (PD-L1^-CD80⁺) adopted a dendritic morphology and adaptive immune functions. P2-pDCs (PD-L1⁺CD80⁺) displayed both innate and adaptive functions. Each subpopulation expressed a specific coding- and long-noncoding-RNA signature and was stable after secondary stimulation. P1-pDCs were detected in samples from patients with lupus or psoriasis. pDC diversification was independent of cell divisions or preexisting heterogeneity within steady-state pDCs but was controlled by a TNF autocrine and/or paracrine communication loop. Our findings reveal a novel mechanism for diversity and division of labor in innate immune cells.

Identification and molecular profiling of DC-SIGN-like from big belly seahorse (Hippocampus abdominalis) inferring its potential relevancy in host immunity

Dendritic-cell-specific ICAM-3-grabbing non-integrin (DC-SIGN) is a C-type lectin that functions as a pattern recognition receptor by recognizing pathogen-associated molecular patterns (PAMPs). It is also involved in various events of the dendritic cell (DC) life cycle, such as DC migration, antigen capture and presentation, and T cell priming. In this study, a DC-SIGN-like gene from the big belly seahorse Hippocampus abdominalis (designated as ShDCS-like) was identified and molecularly characterized. The putative, complete ORF was found to be 1368 bp in length, encoding a protein of 462 amino acids with a molecular mass of 52.6 kDa and a theoretical isoelectric point of 8.26. The deduced amino acid sequence contains a single carbohydrate recognition domain (CRD), in which six conserved cysteine residues and two Ca²⁺-binding site motifs (QPN, WND) were identified. Based on pairwise sequence analysis, ShDCS-like exhibits the highest amino acid identity (94.6%) and similarity (97.4%) with DC-SIGN-like counterpart from tiger tail seahorse Hippocampus comes. Quantitative real-time PCR revealed that ShDCS-like mRNA is transcribed universally in all tissues examined, but with abundance in kidney and gill tissues. The basal mRNA expression of ShDCS-like was modulated in blood cell, kidney, gill and liver tissues in response to the stimulation of healthy fish with lipopolysaccharides (LPS), Edwardsiella tarda, or Streptococcus iniae. Moreover, recombinant ShDCS-like-CRD domain exhibited detectable agglutination activity against different bacteria. Collectively, these results suggest that ShDCS-like may potentially involve in immune function in big belly seahorses.

The genetically determined production of the alarmin eosinophil-derived neurotoxin is reduced in visceral leishmaniasis

Visceral leishmaniasis (VL) is the most severe form of leishmaniasis. Recent findings indicate that dendritic cells have a key role in the defense against the Leishmania parasite and that the activity of this cell may be modified by the eosinophil secretory protein eosinophil-derived neurotoxin (EDN). We hypothesized that the interactions between dendritic cells and EDN might be of importance in the disease development. Cellular content of EDN was analyzed by ELISA. The single-nucleotide polymorphisms at positions 405, 416, and 1122 in the EDN gene were analyzed by real-time PCR with TaqMan^® reagents. The study cohorts comprised 239 Sudanese subjects (65 healthy controls and 174 with VL) and 300 healthy Swedish controls. The eosinophil content of EDN was lower in VL as compared with controls (p < 0.0001). The EDN405 (G>C) genotype distribution was similar among Swedish and Sudanese controls, whereas VL subjects had a higher prevalence of the EDN405-GG genotype (p < 0.0001). The content of EDN in the eosinophils was closely linked to the EDN405 polymorphism (p = 0.0002). Our findings suggest that the predisposition to acquire VL is related to the genetic polymorphism of the EDN gene and the reduced production by the eosinophil of this gene product.

Hematologic neoplasms: Dendritic cells vaccines in motion

Dendritic cells (DCs) are bone-marrow-derived immune cells accounted for a key role in cancer vaccination as potent antigen-presenting cells within the immune system. Cancer microenvironment can modulate DCs maturation resulting in their accumulation into functional states associated with a reduced antitumor immune response. In this regard, a successful cancer vaccine needs to mount a potent antitumor immune response able to overcome the immunosuppressive tumor milieu. As a consequence, DCs-based approaches are a safe and promising strategy for improving the therapeutic efficacy in hematological malignancies, particularly in combinations with additional treatments. This review summarizes the most significant evidence about the immunotherapeutic strategies performed to target hematologic neoplasms including the tumoral associated antigens (TAA) pulsed on DCs, whole tumor cell vaccines or leukemia-derived DCs.

Function and Therapeutic Potential of Mesenchymal Stem Cells in Atherosclerosis

Atherosclerosis is a complicated disorder and largely attributable to dyslipidaemia and chronic inflammation. Despite therapeutic advances over past decades, atherosclerosis remains the leading cause of mortality worldwide. Due to their capability of immunomodulation and tissue regeneration, mesenchymal stem cells (MSCs) have evolved as an attractive therapeutic agent in various diseases including atherosclerosis. Accumulating evidences support the protective role of MSCs in all stages of atherosclerosis. In this review, we highlight the current understanding of MSCs including their characteristics such as molecular markers, tissue distribution, migratory property, immune-modulatory competence, etc. We also summarize MSC functions in animal models of atherosclerosis. MSC transplantation is able to modulate cytokine and chemokine secretion, reduce endothelial dysfunction, promote regulatory T cell function, decrease dyslipidemia, and stabilize vulnerable plaques during atherosclerosis development. In addition, MSCs may migrate to lesions where they develop into functional cells during atherosclerosis formation. Finally, the perspectives of MSCs in clinical atherosclerosis therapy are discussed.

Trans-dissemination of exosomes from HIV-1-infected cells fosters both HIV-1 trans-infection in resting CD4+ T lymphocytes and reactivation of the HIV-1 reservoir

Intact HIV-1 and exosomes can be internalized by dendritic cells (DCs) through a common pathway leading to their transmission to CD4⁺ T lymphocytes by means of mechanisms defined as trans-infection and trans-dissemination, respectively. We previously reported that exosomes from HIV-1-infected cells activate both uninfected quiescent CD4⁺ T lymphocytes, which become permissive to HIV-1, and latently infected cells, with release of HIV-1 particles. However, nothing is known about the effects of trans-dissemination of exosomes produced by HIV-1-infected cells on uninfected or latently HIV-1-infected CD4⁺ T lymphocytes. Here, we report that trans-dissemination of exosomes from HIV-1-infected cells induces cell activation in resting CD4⁺ T lymphocytes, which appears stronger with mature than immature DCs. Using purified preparations of both HIV-1 and exosomes, we observed that mDC-mediated trans-dissemination of exosomes from HIV-1-infected cells to resting CD4⁺ T lymphocytes induces efficient trans-infection and HIV-1 expression in target cells. Most relevant, when both mDCs and CD4⁺ T lymphocytes were isolated from combination anti-retroviral therapy (ART)-treated HIV-1-infected patients, trans-dissemination of exosomes from HIV-1-infected cells led to HIV-1 reactivation from the viral reservoir. In sum, our data suggest a role of exosome trans-dissemination in both HIV-1 spread in the infected host and reactivation of the HIV-1 reservoir.

Immunomodulation by Mesenchymal Stromal Cells and Their Clinical Applications

Mesenchymal stromal cells (MSCs) are multipotent progenitor cells that can be isolated and expanded from various sources. MSCs modulate the function of immune cells, including T and B lymphocytes, dendritic cells, and natural killer cells. An understanding of the interaction between MSCs and the inflammatory microenvironment will provide critical information in revealing the precise in vivo mechanisms involved in MSCs-mediated therapeutic effects, and for designing more practical protocols for the clinical use of these cells. In this review we describe the current knowledge of the unique biological properties of MSCs, the immunosuppressive effects on immune-competent cells and the paracrine role of soluble factors. A summary of the participation of MSCs in preclinical and clinical studies in treating autoimmune diseases and other diseases is described. We also discuss the current challenges of their use and their potential roles in cell therapies.

Participation of mesenchymal stem cells in the regulation of immune response and cancer development

The relevance of the microenvironment in the initiation, promotion, and progression of cancer has been postulated. Mesenchymal stem cells (MSCs) have been identified as important components of the tumor stroma, which are capable of affecting the development of cancer through various mechanisms. In particular, MSCs immunosuppressive properties play an important role. It has been shown that bone marrow-derived and other healthy tissues-derived MSCs are capable of regulating the immune response by affecting the activation, maturation, proliferation, differentiation, and effector function of cells of the immune system, such as neutrophils, macrophages, dendritic cells, natural killer cells (NK) and T-lymphocytes. Similar mechanisms have been identified in MSCs associated with different types of tumors, where they generate an immunosuppressive microenvironment by decreasing the cytotoxic activity of T-lymphocytes and NK cells, skew macrophage differentiation towards an M2 phenotype, and decrease the secretion of Th1-type cytokines. Also, the cytokines, chemokines, and factors secreted by the transformed cells or other cells from the tumor stroma are capable of modulating the functions of MSCs.

Functionally aberrant dendritic cell subsets and expression of DC-SIGN differentiate acute from chronic HBV infection

BACKGROUND

Dendritic cells (DCs) promote pathogen recognition, uptake and presentation of antigen through DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN) and toll-like receptors (TLRs).

AIMS AND OBJECTIVES

We aimed to study temporal changes in DCs, TLRs and DC-SIGN during acute viral hepatitis B (AVHB) infection and compare them to chronic (CHB) and to investigate the earliest time point of activated pathogen recognition receptors in hepatitis B viral infection.

METHODS

We measured the frequencies of circulating myeloid (mDC) and plasmacytoid (pDC) dendritic cells and IFN-α production along with the expression of DC-SIGN and Toll Like Receptors (TLR's) in HBV patients at different time points. Also investigated in healthy volunteers, the dynamic changes in TLRs expression after receiving hepatitis B vaccine.

RESULTS

On follow-up of AVHB patients, we found the mDC population was significantly higher at week 4 and 6 (p < 0.02, 0.01), whereas the pDC population was unchanged at week 6 compared with week 0. Whereas frequencies of mDCs and pDCs were found to be elevated in AVHB and CHB patients than HC (p < 0.00 and 0.01, respectively) but was comparable among AVHB vs CHB. The DCs in CHB patients were functionally impaired with significantly low IFN-α production and low DCSIGN expression (p < 0.04 and 0.00, respectively). Even after stimulation by TLR agonists, no change was found in IFN-α production in CHB patients. MyD88 and IL-6, IFN-α mRNA levels were also found down-regulated. Interestingly, on follow-up after HBV vaccine, TLRs expression was found high at day 3 after vaccination.

DISCUSSION

The initial events of immune activation might be responsible for modulating immune response. These novel observations would pave the way for the development of antiviral strategies for chronic HBV infection.

The histone demethylase inhibitor GSK-J4 limits inflammation through the induction of a tolerogenic phenotype on DCs

As it has been established that demethylation of lysine 27 of histone H3 by the lysine-specific demethylase JMJD3 increases immune responses and thus elicits inflammation, we hypothesize that inhibition of JMJD3 may attenuate autoimmune disorders. We found that in vivo administration of GSK-J4, a selective inhibitor of JMJD3 and UTX, ameliorates the severity of experimental autoimmune encephalomyelitis (EAE). In vitro experiments revealed that the anti-inflammatory effect of GSK-J4 was exerted through an effect on dendritic cells (DCs), promoting a tolerogenic profile characterized by reduced expression of costimulatory molecules CD80/CD86, an increased expression of tolerogenic molecules CD103 and TGF-β1, and reduced secretion of proinflammatory cytokines IL-6, IFN-γ, and TNF. Adoptive transfer of GSK-J4-treated DCs into EAE mice reduced the clinical manifestation of the disease and decreased the extent of inflammatory CD4+ T cells infiltrating the central nervous system. Notably, Treg generation, stability, and suppressive activity were all exacerbated by GSK-J4-treated DCs without affecting Th1 and Th17 cell production. Our data show that GSK-J4-mediated modulation of inflammation is achieved by a direct effect on DCs and that systemic treatment with GSK-J4 or adoptive transfer of GSK-J4-treated DCs ex vivo may be promising approaches for the treatment of inflammatory and autoimmune disorders.

Regulation of differentiation and functional properties of monocytes and monocyte-derived dendritic cells by interferon beta in multiple sclerosis

Interferon beta (IFN beta) has complex immune regulatory properties that contribute to its treatment effect on multiple sclerosis (MS). In this study, we investigated the role of IFN beta in differentiation and functional properties of monocytes and monocyte-derived dendritic cells that are critical to the inflammatory process in MS. The results revealed that IFN beta inhibited intracellular production of interleukin (IL)-1b (PB/0.01) in both monocytes exposed toin vitro treatment of IFN beta and monocytes analysedex vivo from MS patients treated with IFN beta. IFN beta was shown to modulate differentiation of monocytes into dendritic cells in the presence of IL-4 and GM-CSF, which resulted in a delayed differentiation process. Furthermore, it characteristically altered the phenotypic features of differentiated dendritic cells by inhibiting the expression of CD1a, CD11b, CD11c, CD123 and CD209 while upregulating costimulatory molecules, such as CD86. The selective regulatory properties of IFN beta appeared to render the function of differentiated dendritic cells to produce an increased amount (PB/0.01) while their ability to secrete proinflammatory IL-12 and TGF beta was significantly reduced. The observed collective effects of IFN beta seemed to correlate with Th2 immune deviation. The study has provided new insights into the regulatory mechanisms of IFN beta in the treatment of MS.

Human Chorionic Villous Mesenchymal Stem Cells Modify the Functions of Human Dendritic Cells, and Induce an Anti-Inflammatory Phenotype in CD1+ Dendritic Cells

BACKGROUND

Mesenchymal stem cells derived from the chorionic villi of human term placenta (pMSCs) have drawn considerable interest because of their multipotent differentiation potential and their immunomodulatory capacity. These properties are the foundation for their clinical application in the fields of stem cell transplantation and regenerative medicine. Previously, we showed that pMSCs induce an anti-inflammatory phenotype in human macrophages. In this study, we determined whether pMSCs modify the differentiation and maturation of human monocytes into dendritic cells (DCs). The consequences on dendritic function and on T cell proliferation were also investigated.

METHODS

Interleukin-4 (IL-4) and granulocyte-macrophage colony stimulating factor (GM-CSF) were used to stimulate the differentiation of monocytes into immature dendritic cells (iDCs), which were subsequently co-cultured with pMSCs. Lipopolysaccharide (LPS) was used to induce maturation of iDCs into mature dendritic cells (mDCs). Flow cytometry and enzyme-linked immunosorbent assays (ELISA) were used to quantify the effect pMSC co-culturing on DC differentiation using CD1a, a distinctive marker of DCs, as well as other molecules important in the immune functions of DCs. The phagocytic activity of iDCs co-cultured with pMSCs, and the effects of iDCs and mDC stimulation on T cell proliferation, were also investigated.

RESULTS

Monocyte differentiation into iDCs was inhibited when co-cultured with pMSCs and maturation of iDCs by LPS treatment was also prevented in the presence of pMSCs as demonstrated by reduced expression of CD1a and CD83, respectively. The inhibitory effect of pMSCs on iDC differentiation was dose dependent. In addition, pMSC co-culture with iDCs and mDCs resulted in both phenotypic and functional changes as shown by reduced expression of costimulatory molecules (CD40, CD80, CD83 and CD86) and reduced capacity to stimulate CD4(+) T cell proliferation. In addition, pMSC co-culture increased the surface expression of major histocompatibility complex (MHC-II) molecules on iDCs but decreased MHC-II expression on mDCs. Moreover, pMSC co-culture with iDCs or mDCs increased the expression of immunosuppressive molecules [B7H3, B7H4, CD273, CD274 and indoleamine-pyrrole 2,3-dioxygenase (IDO). Additionally, the secretion of IL-12 and IL-23 by iDCs and mDCs co-cultured with pMSCs was decreased. Furthermore, pMSC co-culture with mDCs decreased the secretion of IL-12 and INF-γ whilst increasing the secretion of IL-10 in a T cell proliferation experiment. Finally, pMSC co-culture with iDCs induced the phagocytic activity of iDCs.

CONCLUSIONS

We have shown that pMSCs have an inhibitory effect on the differentiation, maturation and function of DCs, as well as on the proliferation of T cells, suggesting that pMSCs can control the immune responses at multiple levels.

TLR5 mediates CD172α(+) intestinal lamina propria dendritic cell induction of Th17 cells

Multiple mechanisms exist in regulation of host responses to massive challenges from microbiota to maintain immune homeostasis in the intestines. Among these is the enriched Th17 cells in the intestines, which regulates intestinal homeostasis through induction of antimicrobial peptides and secretory IgA among others. However, the means by which Th17 cells develop in response to microbiota is still not completely understood. Although both TLR5 and CD172α(+) lamina propria dendritic cells (LPDC) have been shown to promote Th17 cell development, it is still unclear whether TLR5 mediates the CD172α(+)LPDC induction of Th17 cells. By using a microbiota antigen-specific T cell reporter mouse system, we demonstrated that microbiota antigen-specific T cells developed into Th17 cells in the intestinal LP, but not in the spleen when transferred into TCRβxδ(-/-) mice. LPDCs expressed high levels of TLR5, and most CD172α(+)LPDCs also co-expressed TLR5. LPDCs produced high levels of IL-23, IL-6 and TGFβ when stimulated with commensal flagellin and promoted Th17 cell development when cultured with full-length CBir1 flagellin but not CBir1 peptide. Wild-type CD172α(+), but not CD172α(-), LPDCs induced Th17 cells, whereas TLR5-deficient LPDC did not induce Th17 cells. Our data thereby demonstrated that TLR5 mediates CD172α(+)LPDC induction of Th17 cells in the intestines.

In vitro controlled release of antigen in dendritic cells using pH-sensitive liposome-polymeric hybrid nanoparticles

A hybrid nanoparticle (NP) consisting of a pH sensitive lipid shell and a poly(lactic-co-glycolic) acid (PLGA) core was constructed. This hybrid NP has a mean size of 120.1 ± 8.8 nm and positively charged surface (zeta potential of 14.2 ± 1.4 mV). The lipid shell of the hybrid NP was quickly disintegrated in buffer with a pH of 5.5, which resembles the acidic environment of endosomes in dendritic cell (DC). Less than 20% of the antigen enclosed in pH-sensitive hybrid NP was released into human serum at physiological pH within 24 h, but more than 40% of the enclosed antigen was released within 8 h after pH was adjusted to 5.5. Fast uptake of the pH sensitive hybrid NP by DC was also observed. It was found that pH sensitive hybrid NP displayed faster degradation and antigen release compared to regular hybrid NPs after uptake by DC.