Tolerogenic dendritic cells

Exosomal Non-coding RNA Derived from Mesenchymal Stem Cells (MSCs) in Autoimmune Diseases Progression and Therapy; an Updated Review

Inflammation and autoimmune diseases (AD) are common outcomes of an overactive immune system. Inflammation occurs due to the immune system reacting to damaging stimuli. Exosomes are being recognized as an advanced therapeutic approach for addressing an overactive immune system, positioning them as a promising option for treating AD. Mesenchymal stem cells (MSCs) release exosomes that have strong immunomodulatory effects, influenced by their cell of origin. MSCs-exosomes, being a cell-free therapy, exhibit less toxicity and provoke a diminished immune response compared to cell-based therapies. Exosomal non-coding RNAs (ncRNA), particularly microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are intricately linked to various biological and functional aspects of human health. Exosomal ncRNAs can lead to tissue malfunction, aging, and illnesses when they experience tissue-specific alterations as a result of various internal or external problems. In this study, we will examine current trends in exosomal ncRNA researches regarding AD. Then, therapeutic uses of MSCs-exosomal ncRNA will be outlined, with a particle focus on the underlying molecular mechanisms.

TolDC Restores the Balance of Th17/Treg via Aryl Hydrocarbon Receptor to Attenuate Colitis

BACKGROUND

Tolerogenic dendritic cells (TolDCs) have been evidenced to trigger regulatory T cell's (Treg's) differentiation and be involved in the pathogenesis of Crohn's disease (CD). Aryl hydrocarbon receptor (AhR) plays a crucial role in the differentiation of TolDCs, although the mechanism remains vague. This study aimed to evaluate the role of AhR in TolDCs formation, which may affect Th17/Treg balance in CD.

METHODS

Colon biopsy specimens were obtained from healthy controls and patients with CD. Wild type (WT) and AhR-/- mice were induced colitis by drinking dextran sulphate sodium (DSS) with or without 6-formylindolo 3,2-b carbazole (FICZ) treatment. Wild type and AhR-/- bone marrow-derived cells (BMDCs) were cultured under TolDCs polarization condition. Ratios of DCs surface markers were determined by flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was performed to quantify the levels of interleukin (IL)-1β, transforming growth factor (TGF)-β and IL-10. Tolerogenic dendritic cells differentiated from BMDCs of WT or AhR-/- mice were adoptively transferred to DSS-induced WT colitis mice.

RESULTS

Patients with CD showed less AhR expression and activation in their inflamed colon regions. Compared with WT mice, AhR-/- mice experienced more severe colitis. Tolerogenic dendritic cells and Tregs were both decreased in the colon of AhR-/- colitis mice, while Th17 cells were upregulated. In vitro, compared with WT DCs, AhR-deficient DCs led to less TolDC formation. Furthermore, intestinal inflammation in WT colitis mice, which transferred with AhR-/- TolDCs, showed no obvious improvement compared with those transferred with WT TolDCs, as evidenced by no rescues of Th17/Treg balance.

CONCLUSIONS

Activation of AhR attenuates experimental colitis by modulating the balance of TolDCs and Th17/Treg. The AhR modulation of TolDCs may be a viable therapeutic approach for CD.

Magnesium Ions Promote the Induction of Immunosuppressive Bone Microenvironment and Bone Repair through HIF-1α-TGF-β Axis in Dendritic Cells

The effect of immunoinflammation on bone repair during the recovery process of bone defects needs to be further explored. It is reported that Mg2+ can promote bone repair with immunoregulatory effect, but the underlying mechanism on adaptive immunity is still unclear. Here, by using chitosan and hyaluronic acid-coated Mg2+ (CSHA-Mg) in bone-deficient mice, it is shown that Mg2+ can inhibit the activation of CD4+ T cells and increase regulatory T cell formation by inducing immunosuppressive dendritic cells (imDCs). Mechanistically, Mg2+ initiates the activation of the MAPK signaling pathway through TRPM7 channels on DCs. This process subsequently induces the downstream HIF-1α expression, a transcription factor that amplifies TGF-β production and inhibits the effective T cell function. In vivo, knock-out of HIF-1α in DCs or using a HIF-1α inhibitor PX-478 reverses inhibition of bone inflammation and repair promotion upon Mg2+-treatment. Moreover, roxadustat, which stabilizes HIF-1α protein expression, can significantly promote immunosuppression and bone repair in synergism with CSHA-Mg. Thus, the findings identify a key mechanism for DCs and its HIF-1α-TGF-β axis in the induction of immunosuppressive bone microenvironment, providing potential targets for bone regeneration.

Administration of ROS-Scavenging Cerium Oxide Nanoparticles Simply Mixed with Autoantigenic Peptides Induce Antigen-Specific Immune Tolerance against Autoimmune Encephalomyelitis

The scavenging ability of cerium oxide nanoparticles (CeNPs) for reactive oxygen species has been intensively studied in the field of catalysis. However, the immunological impact of these particles has not yet been thoroughly investigated, despite intensive research indicating that modulation of the reactive oxygen species could potentially regulate cell fate and adaptive immune responses. In this study, we examined the intrinsic capability of CeNPs to induce tolerogenic dendritic cells via their reactive oxygen species-scavenging effect when the autoantigenic peptides were simply mixed with CeNPs. CeNPs effectively reduced the intracellular reactive oxygen species levels in dendritic cells in vitro, leading to the suppression of costimulatory molecules as well as NLRP3 inflammasome activation, even in the presence of pro-inflammatory stimuli. Subcutaneously administrated PEGylated CeNPs were predominantly taken up by antigen-presenting cells in lymph nodes and to suppress cell maturation in vivo. The administration of a mixture of PEGylated CeNPs and myelin oligodendrocyte glycoprotein peptides, a well-identified autoantigen associated with antimyelin autoimmunity, resulted in the generation of antigen-specific Foxp3+ regulatory T cells in mouse spleens. The induced peripheral regulatory T cells actively inhibited the infiltration of autoreactive T cells and antigen-presenting cells into the central nervous system, ultimately protecting animals from experimental autoimmune encephalomyelitis when tested using a mouse model mimicking human multiple sclerosis. Overall, our findings reveal the potential of CeNPs for generating antigen-specific immune tolerance to prevent multiple sclerosis, opening an avenue to restore immune tolerance against specific antigens by simply mixing the well-identified autoantigens with the immunosuppressive CeNPs.

Recombinant human IL-37 attenuates acute cardiac allograft rejection in mice

BACKGROUND

Allograft rejection remains a major obstacle to long-term graft survival. Although previous studies have demonstrated that IL-37 exhibited significant immunomodulatory effects in various diseases, research on its role in solid organ transplantation has not been fully elucidated. In this study, the therapeutic effect of recombinant human IL-37 (rhIL-37) was evaluated in a mouse cardiac allotransplantation model.

METHODS

The C57BL/6 recipients mouse receiving BALB/c donor hearts were treated with rhIL-37. Graft pathological and immunohistology changes, immune cell populations, and cytokine profiles were analyzed on postoperative day (POD) 7. The proliferative capacities of Th1, Th17, and Treg subpopulations were assessed in vitro. Furthermore, the role of the p-mTOR pathway in rhIL-37-induced CD4+ cell inhibition was also elucidated.

RESULTS

Compared to untreated groups, treatment of rhIL-37 achieved long-term cardiac allograft survival and effectively alleviated allograft rejection indicated by markedly reduced infiltration of CD4+ and CD11c+ cells and ameliorated graft pathological changes. rhIL-37 displayed significantly less splenic populations of Th1 and Th17 cells, as well as matured dendritic cells. The percentages of Tregs in splenocytes were significantly increased in the therapy group. Furthermore, rhIL-37 markedly decreased the levels of TNF-α and IFN-γ, but increased the level of IL-10 in the recipients. In addition, rhIL-37 inhibited the expression of p-mTOR in CD4+ cells of splenocytes. In vitro, similar to the in vivo experiments, rhIL-37 caused a decrease in the proportion of Th1 and Th17, as well as an increase in the proportion of Treg and a reduction in p-mTOR expression in CD4+ cells.

CONCLUSIONS

We demonstrated that rhIL-37 effectively suppress acute rejection and induce long-term allograft acceptance. The results highlight that IL-37 could be novel and promising candidate for prevention of allograft rejection.

Redefining Immune Dynamics in Acute Pancreatitis: The Protective Role of Galectin-3 Deletion and Treg Cell Enhancement

Acute pancreatitis (AP) is a complex inflammatory condition that can lead to systemic inflammatory responses and multiple organ dysfunction. This study investigates the role of Galectin-3 (Gal-3), a β-galactoside-binding lectin, in modulating acquired immune responses in AP. Acute pancreatitis was induced by ligation of the bile-pancreatic duct in wild-type and Galectin-3-deficient C57BL/6 mice. We determined the phenotypic and molecular features of inflammatory cells, serum concentrations of amylase, pancreatic trypsin activity, and pancreatic and lung pathology. Galectin-3 deficiency decreased the total number of CD3+CD49- T cells and CD4+ T helper cells, downregulated the production of inflammatory cytokine and IFN-γ, and increased the accumulation of IL-10-producing Foxp3+ T regulatory cells and regulatory CD4+ T cells in the pancreata of diseased animals. The deletion of Galectin-3 ameliorates acute pancreatitis characterized by lowering serum amylase concentration and pancreatic trypsin activity, and attenuating of the histopathology of the lung. These findings shed light on the role of Galectin-3 in acquired immune response in acute pancreatitis and identify Galectin-3 as an attractive target for investigation of the immunopathogenesis of disease and for consideration as a potential therapeutic target for patients with acute inflammatory disease of the pancreas.

Emerging strategies for treating autoimmune disease with genetically modified dendritic cells

Gene editing of living cells has become a crucial tool in medical research, enabling scientists to address fundamental biological questions and develop novel strategies for disease treatment. This technology has particularly revolutionized adoptive transfer cell therapy products, leading to significant advancements in tumor treatment and offering promising outcomes in managing transplant rejection, autoimmune disorders, and inflammatory diseases. While recent clinical trials have demonstrated the safety of tolerogenic dendritic cell (TolDC) immunotherapy, concerns remain regarding its effectiveness. This review aims to discuss the application of gene editing techniques to enhance the tolerance function of dendritic cells (DCs), with a particular focus on preclinical strategies that are currently being investigated to optimize the tolerogenic phenotype and function of DCs. We explore potential approaches for in vitro generation of TolDCs and provide an overview of emerging strategies for modifying DCs. Additionally, we highlight the primary challenges hindering the clinical adoption of TolDC therapeutics and propose future research directions in this field.

Role of sulfatide-reactive vNKT cells in promoting lung Treg cells via dendritic cell modulation in asthma models

Our previous studies have showed that sulfatide-reactive type II NKT (i.e. variant NKT, vNKT) cells inhibit the immunogenic maturation during the development of mature lung dendritic cells (LDCs), leading todeclined allergic airway inflammation in asthma. Nonetheless, the specific immunoregulatory roles of vNKT cells in LDC-mediated Th2 cell responses remain incompletely understood. Herein, we found that administration of sulfatide facilitated the generation of CD4+FoxP3+ regulatory T (Treg) cells in the lungs of wild-type mice, but not in CD1d-/- and Jα18-/- mice, after ovalbumin or house dust mite exposure. This finding implies that the enhancement of lung Treg cells by sulfatide requires vNKT cells, which dependent on invariant NKT (iNKT) cells. Furthermore, the CD4+FoxP3+ Treg cells induced by sulfatide-reactive vNKT cells were found to be associated with PD-L1 molecules expressed on LDCs, and this association was dependent on iNKT cells. Collectively, our findings suggest that in asthma-mimicking murine models, sulfatide-reactive vNKT cells facilitate the generation of lung Treg cells through inducing tolerogenic properties in LDCs, and this process is dependent on the presence of lung iNKT cells. These results may provide a potential therapeutic approach to treat allergic asthma.

Immunomodulatory and Anti-Inflammatory Effects of Vitamin A and Tryptophan on Monocyte-Derived Dendritic Cells Stimulated with Gliadin in Celiac Disease Patients

Celiac Disease (CeD) is an autoimmune disorder with various symptoms upon gluten exposure. Dendritic cells (DCs) play a crucial role in gliadin-induced inflammation. Vitamin A (retinol; Ret) and its metabolite, retinoic acid (RA), along with tryptophan (Trp) and its metabolite, kynurenic acid (KYNA), are known to influence the immune function of DCs and enhance their tolerogenicity. This research aims to assess the impact of gliadin on DC maturation and the potential of vitamin A and tryptophan to induce immune tolerance in DCs. The monocyte cells obtained from peripheral blood mononuclear cells (PBMCs) of celiac disease patients were differentiated into DCs in the absence or presence of Ret, RA, Trp, KYNA, and then stimulated with peptic and tryptic (PT) digested of gliadin. We used flow cytometry to analyze CD11c, CD14, HLA-DR, CD83, CD86, and CD103 expression. ELISA was carried out to measure TGF-β, IL-10, IL-12, and TNF-α levels. qRT-PCR was used to assess the mRNA expression of retinaldehyde dehydrogenase 2 (RALDH2) and integrin αE (CD103). The mRNA and protein levels of Indoleamine 2, 3-dioxygenase (IDO) was analyzed by qRT-PCR and Western blot assays, respectively. Our findings demonstrate that PT-gliadin enhances the expression of maturation markers, i.e. CD83, CD86 and HLA-DR and promote the secretion of TNF-α and IL-12 in DCs. Interestingly, vitamin A, tryptophan, and their metabolites increase the expression of CD103, while limiting the expression of HLA-DR, CD83, and CD86. They also enhance RALDH2 and IDO expression and promote the secretion of TGF-β and IL-10, while limiting IL-12 and TNF-α secretion. These findings suggest that vitamin A and tryptophan have beneficial effects on PT-gliadin-stimulated DCs, highlighting their potential as therapeutic agents for celiac disease. However, further research is needed to fully understand their underlying mechanisms of action in these cells.

Role of dendritic cells in spinal cord injury

BACKGROUND

Inflammation can worsen spinal cord injury (SCI), with dendritic cells (DCs) playing a crucial role in the inflammatory response. They mediate T lymphocyte differentiation, activate microglia, and release cytokines like NT-3. Moreover, DCs can promote neural stem cell survival and guide them toward neuron differentiation, positively impacting SCI outcomes.

OBJECTIVE

This review aims to summarize the role of DCs in SCI-related inflammation and identify potential therapeutic targets for treating SCI.

METHODS

Literature in PubMed and Web of Science was reviewed using critical terms related to DCs and SCI.

RESULTS

The study indicates that DCs can activate microglia and astrocytes, promote T-cell differentiation, increase neurotrophin release at the injury site, and subsequently reduce secondary brain injury and enhance functional recovery in the spinal cord.

CONCLUSIONS

This review highlights the repair mechanisms of DCs and their potential therapeutic potential for SCI.

GENERATION OF TOLEROGENIC DENDRITIC CELLS UNDER THE PERSISTENT INFLAMMATION STIMULATION

ABSTRACT

Immunosuppression, commonly accompanied by persistent inflammation, is a key feature in the later phase of sepsis. However, the pathophysiological mechanisms underlying this phenomenon remain unclear. Dendritic cells (DCs), specifically tolerogenic DCs (tolDCs), play a crucial role in this process by regulating immune responses through inducing T cell anergy and releasing anti-inflammatory cytokines. Nevertheless, the existing cell models are inadequate for investigating tolDCs during the immunosuppressive phase of sepsis. Therefore, this study aimed to develop a novel in vitro model to generate tolDCs under chronic inflammatory conditions. We have successfully generated tolDCs by exposing them to sublethal lipopolysaccharide (LPS) for 72 h while preserving cell viability. Considering that IL-10-induced tolDCs (IL-10-tolDCs) are well-established models, we compared the immunological tolerance between LPS-tolDCs and IL-10-tolDCs. Our findings indicated that both LPS-tolDCs and IL-10-tolDCs exhibited reduced expression of maturation markers, whereas their levels of inhibitory markers were elevated. Furthermore, the immunoregulatory activities of LPS-tolDCs and IL-10-tolDCs were found to be comparable. These dysfunctions include impaired antigen presenting capacity and suppression of T cell activation, proliferation, and differentiation. Notably, compared with IL-10-tolDCs, LPS-tolDCs showed a reduced response in maturation and cytokine production upon stimulation, indicating their potential as a better model for research. Overall, in comparison with IL-10-tolDCs, our data suggest that the immunological dysfunctions shown in LPS-tolDCs could more effectively elucidate the increased susceptibility to secondary infections during sepsis. Consequently, LPS-tolDCs have emerged as promising therapeutic targets for ameliorating the immunosuppressed state in septic patients.

Exosomes: a promising avenue for cancer diagnosis beyond treatment

Exosomes, extracellular vesicles secreted by cells, have garnered significant attention in recent years for their remarkable therapeutic potential. These nanoscale carriers can be harnessed for the targeted delivery of therapeutic agents, such as pharmaceuticals, proteins, and nucleic acids, across biological barriers. This versatile attribute of exosomes is a promising modality for precision medicine applications, notably in the realm of cancer therapy. However, despite their substantial therapeutic potential, exosomes still confront challenges tied to standardization and scalability that impede their practice in clinical applications. Moreover, heterogeneity in isolation methodologies and limited cargo loading mechanisms pose obstacles to ensuring consistent outcomes, thereby constraining their therapeutic utility. In contrast, exosomes exhibit a distinct advantage in cancer diagnosis, as they harbor specific signatures reflective of the tumor's genetic and proteomic profile. This characteristic endows them with the potential to serve as valuable liquid biopsies for non-invasive and real-time monitoring, making possible early cancer detection for the development of personalized treatment strategies. In this review, we provide an extensive evaluation of the advancements in exosome research, critically examining their advantages and limitations in the context of cancer therapy and early diagnosis. Furthermore, we present a curated overview of the most recent technological innovations utilizing exosomes, with a focus on enhancing the efficacy of early cancer detection.

The Role of the Microbiome in the Etiopathogenesis of Colon Cancer

Studies in preclinical models support that the gut microbiota play a critical role in the development and progression of colorectal cancer (CRC). Specific microbial species and their corresponding virulence factors or associated small molecules can contribute to CRC development and progression either via direct effects on the neoplastic transformation of epithelial cells or through interactions with the host immune system. Induction of DNA damage, activation of Wnt/β-catenin and NF-κB proinflammatory pathways, and alteration of the nutrient's availability and the metabolic activity of cancer cells are the main mechanisms by which the microbiota contribute to CRC. Within the tumor microenvironment, the gut microbiota alter the recruitment, activation, and function of various immune cells, such as T cells, macrophages, and dendritic cells. Additionally, the microbiota shape the function and composition of cancer-associated fibroblasts and extracellular matrix components, fashioning an immunosuppressive and pro-tumorigenic niche for CRC. Understanding the complex interplay between gut microbiota and tumorigenesis can provide therapeutic opportunities for the prevention and treatment of CRC.

Role of immune cells in the pathogenesis of myocarditis

Myocarditis is an inflammatory heart disease that mostly affects young people. Myocarditis involves a complex immune network; however, its detailed pathogenesis is currently unclear. The diversity and plasticity of immune cells, either in the peripheral blood or in the heart, have been partially revealed in a number of previous studies involving patients and several kinds of animal models with myocarditis. It is the complexity of immune cells, rather than one cell type that is the culprit. Thus, recognizing the individual intricacies within immune cells in the context of myocarditis pathogenesis and finding the key intersection of the immune network may help in the diagnosis and treatment of this condition. With the vast amount of cell data gained on myocarditis and the recent application of single-cell sequencing, we summarize the multiple functions of currently recognized key immune cells in the pathogenesis of myocarditis to provide an immune background for subsequent investigations.

Dendritic Cells and the Establishment of Fetomaternal Tolerance for Successful Human Pregnancy

Pregnancy is a remarkable event where the semi-allogeneic fetus develops in the mother's uterus, despite genetic and immunological differences. The antigen handling and processing at the maternal-fetal interface during pregnancy appear to be crucial for the adaptation of the maternal immune system and for tolerance to the developing fetus and placenta. Maternal antigen-presenting cells (APCs), such as macrophages (Mφs) and dendritic cells (DCs), are present at the maternal-fetal interface throughout pregnancy and are believed to play a crucial role in this process. Despite numerous studies focusing on the significance of Mφs, there is limited knowledge regarding the contribution of DCs in fetomaternal tolerance during pregnancy, making it a relatively new and growing field of research. This review focuses on how the behavior of DCs at the maternal-fetal interface adapts to pregnancy's unique demands. Moreover, it discusses how DCs interact with other cells in the decidual leukocyte network to regulate uterine and placental homeostasis and the local maternal immune responses to the fetus. The review particularly examines the different cell lineages of DCs with specific surface markers, which have not been critically reviewed in previous publications. Additionally, it emphasizes the impact that even minor disruptions in DC functions can have on pregnancy-related complications and proposes further research into the potential therapeutic benefits of targeting DCs to manage these complications.

Tolerogenic dendritic cells and TLR4/IRAK4/NF-κB signaling pathway in allergic rhinitis

Dendritic cells (DCs), central participants in the allergic immune response, can capture and present allergens leading to allergic inflammation in the immunopathogenesis of allergic rhinitis (AR). In addition to initiating antigen-specific immune responses, DCs induce tolerance and modulate immune homeostasis. As a special type of DCs, tolerogenic DCs (tolDCs) achieve immune tolerance mainly by suppressing effector T cell responses and inducing regulatory T cells (Tregs). TolDCs suppress allergic inflammation by modulating immune tolerance, thereby reducing symptoms of AR. Activation of the TLR4/IRAK4/NF-κB signaling pathway contributes to the release of inflammatory cytokines, and inhibitors of this signaling pathway induce the production of tolDCs to alleviate allergic inflammatory responses. This review focuses on the relationship between tolDCs and TLR4/IRAK4/NF-κB signaling pathway with AR.

Protective Effect and Mechanisms of Eckol on Chronic Ulcerative Colitis Induced by Dextran Sulfate Sodium in Mice

The use of functional foods and their bioactive components is receiving increasing attention as a complementary and alternative therapy for chronic ulcerative colitis (UC). This study explored the protective effect and mechanisms of Eckol, a seaweed-derived bioactive phlorotannin, on the dextran sodium sulfate (DSS)-induced chronic UC in mice. Eckol (0.5-1.0 mg/kg) reduced DSS-enhanced disease activity indexes, and alleviated the shortening of colon length and colonic tissue damage in chronic UC mice. The contents of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were significantly decreased, and the level of anti-inflammatory IL-10 was enhanced in the serum and colonic tissues collected from Eckol-treated mice compared with the DSS controls. Eckol administration significantly reduced the number of apoptotic cells and the expression of cleaved Caspase-3, and increased the B-cell lymphoma-2 (Bcl-2)/B-cell lymphoma-2- associated X (Bax) ratio in DSS-challenged colons. There were more cluster of differentiation (CD)11c⁺ dendritic cells and CD8⁺ T cells, and less CD4⁺ T cells infiltrated to inflamed colonic tissues in the Eckol-treated groups. Expression of colonic Toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB) p65, phosphorylated-signal transducer and activator of transcription (pSTAT)3 was significantly down-regulated by Eckol compared with the DSS-challenged group. In conclusion, our data suggest that Eckol appeared to be a potential functional food ingredient for protection against chronic UC. The anti-colitis mechanisms of Eckol might be attributed to the down-regulation of the TLR4/NF-κB/STAT3 pathway, inhibition of inflammation and apoptosis, as well as its immunoregulatory activity.

Tolerogenic dendritic cells in type 1 diabetes: no longer a concept

Tolerogenic dendritic cells (tDC) arrest the progression of autoimmune-driven dysglycemia into clinical, insulin-requiring type 1 diabetes (T1D) and preserve a critical mass of β cells able to restore some degree of normoglycemia in new-onset clinical disease. The safety of tDC, generated ex vivo from peripheral blood leukocytes, has been demonstrated in phase I clinical studies. Accumulating evidence shows that tDC act via multiple layers of immune regulation arresting the action of pancreatic β cell-targeting effector lymphocytes. tDC share a number of phenotypes and mechanisms of action, independent of the method by which they are generated ex vivo. In the context of safety, this yields confidence that the time has come to test the best characterized tDC in phase II clinical trials in T1D, especially given that tDC are already being tested for other autoimmune conditions. The time is also now to refine purity markers and to "universalize" the methods by which tDC are generated. This review summarizes the current state of tDC therapy for T1D, presents points of intersection of the mechanisms of action that the different embodiments use to induce tolerance, and offers insights into outstanding matters to address as phase II studies are imminent. Finally, we present a proposal for co-administration and serially-alternating administration of tDC and T-regulatory cells (Tregs) as a synergistic and complementary approach to prevent and treat T1D.

Dendritic Cells as a Nexus for the Development of Multiple Sclerosis and Models of Disease

Multiple sclerosis (MS) results from an autoimmune attack on the central nervous system (CNS). Dysregulated immune cells invade the CNS, causing demyelination, neuronal and axonal damage, and subsequent neurological disorders. Although antigen-specific T cells mediate the immunopathology of MS, innate myeloid cells have essential contributions to CNS tissue damage. Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that promote inflammation and modulate adaptive immune responses. This review focuses on DCs as critical components of CNS inflammation. Here, evidence from studies is summarized with animal models of MS and MS patients that support the critical role of DCs in orchestrating CNS inflammation.

Innate immune cellular therapeutics in transplantation

Successful organ transplantation provides an opportunity to extend the lives of patients with end-stage organ failure. Selectively suppressing the donor-specific alloimmune response, however, remains challenging without the continuous use of non-specific immunosuppressive medications, which have multiple adverse effects including elevated risks of infection, chronic kidney injury, cardiovascular disease, and cancer. Efforts to promote allograft tolerance have focused on manipulating the adaptive immune response, but long-term allograft survival rates remain disappointing. In recent years, the innate immune system has become an attractive therapeutic target for the prevention and treatment of transplant organ rejection. Indeed, contemporary studies demonstrate that innate immune cells participate in both the initial alloimmune response and chronic allograft rejection and undergo non-permanent functional reprogramming in a phenomenon termed "trained immunity." Several types of innate immune cells are currently under investigation as potential therapeutics in transplantation, including myeloid-derived suppressor cells, dendritic cells, regulatory macrophages, natural killer cells, and innate lymphoid cells. In this review, we discuss the features and functions of these cell types, with a focus on their role in the alloimmune response. We examine their potential application as therapeutics to prevent or treat allograft rejection, as well as challenges in their clinical translation and future directions for investigation.

Donor Batf3 inhibits murine lung allograft rejection and airway fibrosis

Chronic lung allograft dysfunction (CLAD) limits survival after lung transplantation. Noxious stimuli entering the airways foster CLAD development. Classical dendritic cells (cDCs) link innate and adaptive immunity and exhibit regional and functional specialization in the lung. The transcription factor basic leucine zipper ATF-like 3 (BATF3) is absolutely required for the development of type 1 cDCs (cDC1s), which reside in the airway epithelium and have variable responses depending on the context. We studied the role of BATF3 in a mouse minor alloantigen-mismatched orthotopic lung transplant model of CLAD with and without airway inflammation triggered by repeated administration of intratracheal lipopolysaccharide (LPS). We found that cDC1s accumulated in allografts compared with isografts and that donor cDC1s were gradually replaced by recipient cDC1s. LPS administration increased the number of cDC1s and enhanced their state of activation. We found that Batf3^-/- recipient mice experienced reduced acute rejection in response to LPS; in contrast, Batf3^-/- donor grafts underwent enhanced lung and skin allograft rejection and drove augmented recipient cluster of differentiation 8⁺ T-cell expansion in the absence of LPS. Our findings suggest that donor and recipient cDC1s have differing and context-dependent roles and may represent a therapeutic target in lung transplantation.

Effects of Aire on perforin expression in BMDCs via TLR7/8 and its therapeutic effect on type 1 diabetes

AIMS

Type 1 diabetes, as a kind of autoimmune diseases, usually results from the broken-down of self-tolerance. Autoimmune regulator (Aire), as a transcription factor, induces peripheral tolerance by regulating Toll-like receptor (TLR) expression in dendritic cells (DCs). Several studies have recently identified a small population of perforin-expressing DCs, which is an important population of tolerogenic DCs (tolDCs) that restricts autoreactive T cells in vivo through a perforin-mediated mechanism. Thus, the present study explored the specific relationship among Aire, perforin-expressing DCs and immune tolerance, as well as their roles in type 1 diabetes.

METHODS

We conducted studies based on the Aire-overexpressing bone marrow-derived dendritic cell (BMDC) model. And through in vitro and in vivo experiments to observe that Aire-overexpressing BMDCs which express perforin induce immune tolerance and treat type 1 diabetes via TLR7/8.

RESULTS

Aire enhances the expression of perforin in BMDCs after treatment with the TLR7/8 ligand as well as promotes the expression of TLR7/8 and myeloid differentiation primary response gene 88 (MyD88)-dependent pathway molecules. Aire-overexpressing BMDCs mediate apoptosis of allogeneic CD8⁺ T cells via perforin in vitro. Moreover, Aire-overexpressing BMDCs enhance the therapeutic effect of type 1 diabetes in non-obese diabetic (NOD) mice via perforin and induce apoptosis of autoreactive CD8⁺ T cells in vivo.

CONCLUSIONS

These results provide an experimental basis for comprehensively elucidating the role and significance of Aire expression in peripheral DCs, thereby providing new ideas for the treatment of autoimmune diseases by using Aire as a target to induce the production of perforin-expressing DCs.

T cell receptor signaling in the differentiation and plasticity of CD4+ T cells

CD4⁺ T cells are critical components of the adaptive immune system. The T cell receptor (TCR) and co-receptor signaling cascades shape the phenotype and functions of CD4⁺ T cells. TCR signaling plays a crucial role in T cell development, antigen recognition, activation, and differentiation upon recognition of foreign- or auto-antigens. In specific autoimmune conditions, altered TCR repertoire is reported and can predispose autoimmunity with organ-specific inflammation and tissue damage. TCR signaling modulates various signaling cascades and regulates epigenetic and transcriptional regulation during homeostasis and disease conditions. Understanding the mechanism by which coreceptors and cytokine signals control the magnitude of TCR signal amplification will aid in developing therapeutic strategies to treat inflammation and autoimmune diseases. This review focuses on the role of the TCR signaling cascade and its components in the activation, differentiation, and plasticity of various CD4⁺ T cell subsets.

Recent insight into autophagy and immunity at the maternal-fetal interface

Autophagy is a lysosomal degradation pathway that supports metabolic adaptation and energy cycling. It is essential for cell homeostasis, differentiation, development, and survival. Recent studies have shown that autophagy could influence immune responses by regulating immune cell functions. Reciprocally, immune cells strongly influence autophagy. Immune cells at the maternal-fetal interface are thought to play essential roles in pregnancy. Here, we review the induction of autophagy at the maternal-fetal interface and its role in decidualization and placental development. Additionally, we emphasize the role of autophagy in the immune microenvironment at the maternal-fetal interface, including innate immunity, adaptive immunity, and immune tolerance molecules. It also suggests new research directions and prospects.

The emerging role of exosomes in innate immunity, diagnosis and therapy

Exosomes, which are nano-sized transport bio-vehicles, play a pivotal role in maintaining homeostasis by exchanging genetic or metabolic information between different cells. Exosomes can also play a vital role in transferring virulent factors between the host and parasite, thereby regulating host gene expression and the immune interphase. The association of inflammation with disease development and the potential of exosomes to enhance or mitigate inflammatory pathways support the notion that exosomes have the potential to alter the course of a disease. Clinical trials exploring the role of exosomes in cancer, osteoporosis, and renal, neurological, and pulmonary disorders are currently underway. Notably, the information available on the signatory efficacy of exosomes in immune-related disorders remains elusive and sporadic. In this review, we discuss immune cell-derived exosomes and their application in immunotherapy, including those against autoimmune connective tissue diseases. Further, we have elucidated our views on the major issues in immune-related pathophysiological processes. Therefore, the information presented in this review highlights the role of exosomes as promising strategies and clinical tools for immune regulation.

Atorvastatin-induced tolerogenic dendritic cells improve cardiac remodeling by suppressing TLR-4/NF-κB activation after myocardial infarction

OBJECTIVE

Myocardial infarction (MI) caused by ischemic cardiomyocyte necrosis induces inflammatory responses that strongly affect ventricular remodeling. Tolerogenic dendritic cells (tDCs) can suppress this effect on inflammatory responses. However, the precise role of atorvastatin-induced tDCs in ventricular remodeling after MI remains unclear.

METHODS

To explore the effect of necrotic cardiomyocytes (SNC) and/or atorvastatin on DC function, the expression of CD40, CD80, CD86, and MHC-II was determined using flow cytometry. The protein levels of TLR-4/NF-κB-related molecules were evaluated using western blotting. The infarct area after MI was determined via 2,3,5-triphenyltetrazolium chloride staining. The TUNEL assay was employed to evaluate the apoptosis of cardiomyocytes in heart sections. Masson's trichrome method was used to determine the extent of fibrosis.

RESULTS

Compared to the DCs co-cultured with PBS (control), cells co-cultured with Supernatant-IM or Supernatant-NH produced higher levels of inflammatory cytokines, including TNF-α, IL-1, IL-6, IL-12P40, and IL-8. This cytokine production was impaired by atorvastatin treatment. SNC treatment induced DC maturation and enhanced inflammatory cytokine secretion and oxidative stress through TLR-4/NF-κB pathway activation. Compared to that in the PBS-treated group, the left ventricular ejection fraction was significantly improved after tDC treatment. Additionally, compared to that in the PBS-treated group, tDC treatment reduced the left ventricular end-diastolic and end-systolic diameters in mice. Furthermore, treatment with tDCs improved the left ventricular systolic function, attenuated inflammatory cell infiltration, and reduced cardiomyocyte apoptosis, myocardial fibrosis, and infarct size compared to those in the control group.

CONCLUSIONS

Adoptive transfer of atorvastatin-induced tDCs alleviated post-infarction cardiomyocyte apoptosis and myocardial fibrosis in association with decreased inflammatory cell infiltration and inhibited oxidative stress, likely by suppressing TLR-4/NF-κB activation after myocardial infarction.

Aberrant tolerogenic functions and proinflammatory skew of dendritic cells in STAT1 gain-of-function patients may contribute to autoimmunity and fungal susceptibility

STAT1 gain-of-function (GOF) mutations underlie an inborn error of immunity hallmarked by chronic mucocutaneous candidiasis (CMC). Beyond the fungal susceptibility, attributed to Th17 failure, over half of the reported patients suffer from autoimmune manifestations, mechanism of which has not been explained yet. We hypothesized that the STAT1 mutations would affect dendritic cells' (DCs) properties and alter their inflammatory and tolerogenic functions. To test the hypothesis, we generated monocyte-derived DCs (moDCs) and tolerogenic DCs (tDCs). Functional and signaling studies, co-culture experiments and RNA sequencing demonstrated that STAT1 GOF DCs were profoundly altered in their phenotype and functions, characterized by loss of tolerogenic functions, proinflammatory skew and decreased capacity to induce Th17. Cytokine signaling, autophagy and metabolic processes were identified as the most prominently altered cellular processes. The results suggest that DCs are directly involved in STAT1 GOF-associated immune pathology, possibly contributing to both autoimmune manifestations and the failure of antifungal defense.

NCoR1 controls immune tolerance in conventional dendritic cells by fine-tuning glycolysis and fatty acid oxidation

Dendritic cells (DCs) undergo rapid metabolic reprogramming to generate signal-specific immune responses. The fine control of cellular metabolism underlying DC immune tolerance remains elusive. We have recently reported that NCoR1 ablation generates immune-tolerant DCs through enhanced IL-10, IL-27 and SOCS3 expression. In this study, we did comprehensive metabolic profiling of these tolerogenic DCs and identified that they meet their energy requirements through enhanced glycolysis and oxidative phosphorylation (OXPHOS), supported by fatty acid oxidation-driven oxygen consumption. In addition, the reduced pyruvate and glutamine oxidation with a broken TCA cycle maintains the tolerogenic state of the cells. Mechanistically, the AKT-mTOR-HIF-1α-axis mediated glycolysis and CPT1a-driven β-oxidation were enhanced in these tolerogenic DCs. To confirm these observations, we used synthetic metabolic inhibitors and found that the combined inhibition of HIF-1α and CPT1a using KC7F2 and etomoxir, respectively, compromised the overall transcriptional signature of immunological tolerance including the regulatory cytokines IL-10 and IL-27. Functionally, treatment of tolerogenic DCs with dual KC7F2 and etomoxir treatment perturbed the polarization of co-cultured naïve CD4⁺ T helper (Th) cells towards Th1 than Tregs, ex vivo and in vivo. Physiologically, the Mycobacterium tuberculosis (Mtb) infection model depicted significantly reduced bacterial burden in BMcDC1 ex vivo and in CD103⁺ lung DCs in Mtb infected NCoR1^DC-/-mice. The spleen of these infected animals also showed increased Th1-mediated responses in the inhibitor-treated group. These findings suggested strong involvement of NCoR1 in immune tolerance. Our validation in primary human monocyte-derived DCs (moDCs) showed diminished NCOR1 expression in dexamethasone-derived tolerogenic moDCs along with suppression of CD4⁺T cell proliferation and Th1 polarization. Furthermore, the combined KC7F2 and etomoxir treatment rescued the decreased T cell proliferative capacity and the Th1 phenotype. Overall, for the first time, we demonstrated here that NCoR1 mediated control of glycolysis and fatty acid oxidation fine-tunes immune tolerance versus inflammation balance in murine and human DCs.

Derivation and external validation of dendritic cell-related gene signatures for predicting prognosis and immunotherapy efficacy in bladder urothelial carcinoma

Background

In the regulation of tumor-related immunity, dendritic cells (DCs) are crucial sentinel cells; they are powerful to present antigens and initiate immune responses. Therefore, we concentrated on investigating the DC-related gene profile, prognosis, and gene mutations in bladder urothelial carcinoma (BLCA) patients to identify sensitivity to immunotherapy of patients.

Methods

According to DC infiltration, BLCA patients were divided into two subgroups, and differentially expressed genes (DEGs) were obtained. Patients were classified by unsupervised clustering into new subgroups. The least absolute shrinkage and selection operator (LASSO) regression analysis and Cox regression were used to develop a DC-related risk model. CIBERSORT, xCell, and GSEA were used to infer immune cells' relative abundance separately and enriched immune pathways.

Results

A total of 29 prognosis-related DEGs were identified from the unsupervised cluster. Among them, 22 genes were selected for constructing the DC-related risk model. The dendritic cell-related risk score (DCRS) can accurately distinguish patients with different sensitive responses to immunotherapy and overall survival outcomes. Furthermore, patients with ryanodine receptor 2 (RYR2) mutation had a better prognosis.

Conclusions

The DCRS played an essential part in immunity pathway and formation of TME diversity. Our study indicated that RYR2 mutation combined with DCRS is useful for predicting the prognosis and discovering appropriate patients for immunotherapy.

Impact of disease-modifying therapy on dendritic cells and exploring their immunotherapeutic potential in multiple sclerosis

Dendritic cells (DCs) are the most potent professional antigen-presenting cells (APCs), which play a pivotal role in inducing either inflammatory or tolerogenic response based on their subtypes and environmental signals. Emerging evidence indicates that DCs are critical for initiation and progression of autoimmune diseases, including multiple sclerosis (MS). Current disease-modifying therapies (DMT) for MS can significantly affect DCs' functions. However, the study on the impact of DMT on DCs is rare, unlike T and B lymphocytes that are the most commonly discussed targets of these therapies. Induction of tolerogenic DCs (tolDCs) with powerful therapeutic potential has been well-established to combat autoimmune responses in laboratory models and early clinical trials. In contrast to in vitro tolDC induction, in vivo elicitation by specifically targeting multiple cell-surface receptors has shown greater promise with more advantages. Here, we summarize the role of DCs in governing immune tolerance and in the process of initiating and perpetuating MS as well as the effects of current DMT drugs on DCs. We then highlight the most promising cell-surface receptors expressed on DCs currently being explored as the viable pharmacological targets through antigen delivery to generate tolDCs in vivo.

Mucosal delivery of nanovaccine strategy against COVID-19 and its variants

Despite the global administration of approved COVID-19 vaccines (e.g., ChAdOx1 nCoV-19®, mRNA-1273®, BNT162b2®), the number of infections and fatalities continue to rise at an alarming rate because of the new variants such as Omicron and its subvariants. Including COVID-19 vaccines that are licensed for human use, most of the vaccines that are currently in clinical trials are administered via parenteral route. However, it has been proven that the parenteral vaccines do not induce localized immunity in the upper respiratory mucosal surface, and administration of the currently approved vaccines does not necessarily lead to sterilizing immunity. This further supports the necessity of a mucosal vaccine that blocks the main entrance route of COVID-19: nasal and oral mucosal surfaces. Understanding the mechanism of immune regulation of M cells and dendritic cells and targeting them can be another promising approach for the successful stimulation of the mucosal immune system. This paper reviews the basic mechanisms of the mucosal immunity elicited by mucosal vaccines and summarizes the practical aspects and challenges of nanotechnology-based vaccine platform development, as well as ligand hybrid nanoparticles as potentially effective target delivery agents for mucosal vaccines.

Wasabi Component 6-(Methylsulfinyl)hexly Isothiocyanate and Derivatives Improve the Survival of Skin Allografts

We tested the effect of 6-(Methylsulfinyl)hexyl Isothiocyanate (6-MITC) and derivatives (I7447 and I7557) on the differentiation and maturation of human myeloid dendritic cells (DCs) in vitro, and skin transplantation in vivo. Triggering of CD14⁺ myeloid monocyte development toward myeloid DCs with and without 6-MITC and derivatives to examine the morphology, viability, surface marker expression, and cytokine production. Stimulatory activity on allogeneic naive T cells was measured by proliferation and interferon-γ production. The skin allograft survival area model was used to translate the 6-MITC and derivatives’ antirejection effect. All of the compounds had no significant effects on DC viability and reduced the formation of dendrites at concentrations higher than 10 μM. At this concentration, 6-MITC and I7557, but not I7447, inhibited the expression of CD1a and CD83. Both 6-MITC and I7557 exhibited T-cells and interferon-γ augmentation at lower concentrations and suppression at higher concentration. The 6-MITC and I7557 prolonged skin graft survival. Both the 6-MITC and I7557 treatment resulted in the accumulation of regulatory T cells in recipient rat spleens. No toxicity was evident in 6-MITC and I7557 treatment. The 6-MITC and I7557 induced human DC differentiation toward a tolerogenic phenotype and prolonged rat skin allograft survival. These compounds may be effective as immunosuppressants against transplant rejection.

Human CD4+/CD8α+ regulatory T cells induced by Faecalibacterium prausnitzii protect against intestinal inflammation

Faecalibacterium prausnitzii (F. prausnitzii), a dominant bacterium of the human microbiota, is decreased in patients with inflammatory bowel diseases (IBD) and exhibits anti-inflammatory effects. In human, colonic lamina propria contains IL-10-secreting, Foxp3-negative regulatory T cells (Treg) characterized by a double expression of CD4 and CD8α (DP8α) and a specificity for F. prausnitzii. This Treg subset is decreased in IBD. The in vivo effect of DP8α cells has not been evaluated yet. Here, using a humanized model of NOD.Prkcscid IL2rγ-/- (NSG) immunodeficient mouse strain that expresses the human leucocyte antigen D-related allele HLA-DR*0401 but not murine class II (NSG-Ab° DR4) molecules, we demonstrated a protective effect of a HLA-DR*0401-restricted DP8α Treg clone combined with F. prausnitzii administration in a colitis model. In a cohort of patients with IBD, we showed an independent association between the frequency of circulating DP8α cells and disease activity. Finally, we pointed out a positive correlation between F. prausnitzii-specific DP8α Tregs and the amount of F. prausnitzii in fecal microbiota in healthy individuals and patients with ileal Crohn's disease.

Nanoparticle-Based Drug Delivery Systems for Induction of Tolerance and Treatment of Autoimmune Diseases

Autoimmune disease is a chronic inflammatory disease caused by disorders of immune regulation. Antigen-specific immunotherapy has the potential to inhibit the autoreactivity of inflammatory T cells and induce antigen-specific immune suppression without impairing normal immune function, offering an ideal strategy for autoimmune disease treatment. Tolerogenic dendritic cells (Tol DCs) with immunoregulatory functions play important roles in inducing immune tolerance. However, the effective generation of tolerogenic DCs in vivo remains a great challenge. The application of nanoparticle-based drug delivery systems in autoimmune disease treatment can increase the efficiency of inducing antigen-specific tolerance in vivo. In this review, we discuss multiple nanoparticles, with a focus on their potential in treatment of autoimmune diseases. We also discuss how the physical properties of nanoparticles influence their therapeutic efficacy.

LILRB4, an immune checkpoint on myeloid cells

Leukocyte immunoglobulin-like receptor B4 (LILRB4) is an inhibitory receptor in the LILR family mainly expressed on normal and malignant human cells of myeloid origin. By binding to ligands, LILRB4 is activated and subsequently recruits adaptors to cytoplasmic immunoreceptor tyrosine inhibitory motifs to initiate different signaling cascades, thus playing an important role in physiological and pathological conditions, including autoimmune diseases, microbial infections, and cancers. In normal myeloid cells, LILRB4 regulates intrinsic cell activation and differentiation. In disease-associated or malignant myeloid cells, LILRB4 is significantly correlated with disease severity or patient survival and suppresses T cells, thereby participating in the pathogenesis of various diseases. In summary, LILRB4 functions as an immune checkpoint on myeloid cells and may be a promising therapeutic target for various human immune diseases, especially for cancer immunotherapy.

Role of indoleamine 2,3-dioxygenase 1 (IDO1) and kynurenine pathway in the regulation of the aging process

Indoleamine 2,3-dioxygenase 1 (IDO1) is activated in chronic inflammatory states, e.g., in the aging process and age-related diseases. IDO1 enzyme catabolizes L-tryptophan (L-Trp) into kynurenine (KYN) thus stimulating the KYN pathway. The depletion of L-Trp inhibits the proliferation of immune cells in inflamed tissues and it also reduces serotonin synthesis predisposing to psychiatric disorders. Interestingly, IDO1 protein contains two immunoreceptor tyrosine-based inhibitory motifs (ITIM) which trigger suppressive signaling through the binding of PI3K p110 and SHP-1 proteins. This immunosuppressive activity is not dependent on the catalytic activity of IDO1. KYN and its metabolite, kynurenic acid (KYNA), are potent activators of the aryl hydrocarbon receptor (AhR) which can enhance immunosuppression. IDO1-KYN-AhR signaling counteracts excessive pro-inflammatory responses in acute inflammation but in chronic inflammatory states it has many harmful effects. A chronic low-grade inflammation is associated with the aging process, a state called inflammaging. There is substantial evidence that the activation of the IDO1-KYN-AhR pathway robustly increases with the aging process. The activation of IDO1-KYN-AhR signaling does not only suppress the functions of effector immune cells, probably promoting immunosenescence, but it also impairs autophagy, induces cellular senescence, and remodels the extracellular matrix as well as enhancing the development of osteoporosis and vascular diseases. I will review the function of IDO1-KYN-AhR signaling and discuss its activation with aging as an enhancer of the aging process.

Pelzer B, Khodamoradi Y, Vehreschild MJGT. The role of the human gut microbiota in colonization and infection with multidrug-resistant bacteria

About 100 years ago, the first antibiotic drug was introduced into health care. Since then, antibiotics have made an outstanding impact on human medicine. However, our society increasingly suffers from collateral damage exerted by these highly effective drugs. The rise of resistant pathogen strains, combined with a reduction of microbiota diversity upon antibiotic treatment, has become a significant obstacle in the fight against invasive infections worldwide.Alternative and complementary strategies to classical "Fleming antibiotics" comprise microbiota-based treatments such as fecal microbiota transfer and administration of probiotics, live-biotherapeutics, prebiotics, and postbiotics. Other promising interventions, whose efficacy may also be influenced by the human microbiota, are phages and vaccines. They will facilitate antimicrobial stewardship, to date the only globally applied antibiotic resistance mitigation strategy.In this review, we present the available evidence on these nontraditional interventions, highlight their interaction with the human microbiota, and discuss their clinical applicability.

Herpes simplex virus interference with immunity: Focus on dendritic cells

Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are highly prevalent in the human population. These viruses cause lifelong infections by establishing latency in neurons and undergo sporadic reactivations that promote recurrent disease and new infections. The success of HSVs in persisting in infected individuals is likely due to their multiple molecular determinants involved in escaping the host antiviral and immune responses. Importantly, HSVs infect and negatively modulate the function of dendritic cells (DCs), key immune cells that are involved in establishing effective and balanced immunity against viruses. Here, we review and discuss several molecular and cellular processes modulated by HSVs in DCs, such as autophagy, apoptosis, and the unfolded protein response. Given the central role of DCs in establishing optimal antiviral immunity, particular emphasis should be given to the outcome of the interactions occurring between HSVs and DCs.

The role of dendritic cells and their interactions in the pathogenesis of antibody-associated autoimmune encephalitis

Autoimmune encephalitis (AE) is an inflammatory brain disease which is frequently associated with antibodies (Abs) against cell-surface, synaptic or intracellular neuronal proteins. There is increasing evidence that dendritic cells (DCs) are implicated as key modulators in keeping the balance between immune response and tolerance in the CNS. Migratory features of DCs to and from the brain are linked to initiating and maintaining of neuroinflammation. Genetic polymorphisms together with other triggers such as systemic or cerebral viral infection, or systemic malignancies could contribute to the dysbalance of "regulatory" and "encephalitogenic" DCs with subsequent dysregulated T and B cell reactions in AE. Novel in vivo models with implantation of mature DCs containing neuronal antigens could help to study the pathogenesis and perhaps to understand the origin of AE. Investigations of DCs in human blood, lymphoid tissues, CSF, and brain parenchyma of patients with AE are necessary to deepen our knowledge about the complex interactions between DCs, T and B cells during neuroinflammation in AE. This can support developing new therapy strategies.

Bioderived materials that disarm the gut mucosal immune system: Potential lessons from commensal microbiota

Over the course of evolution, mammals and gut commensal microbes have adapted to coexist with each other. This homeostatic coexistence is dependent on an intricate balance between tolerogenic and inflammatory responses directed towards beneficial, commensal microbes and pathogenic intruders, respectively. Immune tolerance towards the gut microflora is largely sustained by immunomodulatory molecules produced by the commensals, which protect the bacteria from immune advances and maintain the gut's unique tolerogenic microenvironment, as well as systemic homeostasis. The identification and characterization of commensal-derived, tolerogenic molecules could lead to their utilization in biomaterials-inspired delivery schemes involving nano/microparticles or hydrogels, and potentially lead to the next generation of commensal-derived therapeutics. Moreover, gut-on-chip technologies could augment the discovery and characterization of influential commensals by providing realistic in vitro models conducive to finicky microbes. In this review, we provide an overview of the gut immune system, describe its intricate relationships with the microflora and identify major genera involved in maintaining tolerogenic responses and peripheral homeostasis. More relevant to biomaterials, we discuss commensal-derived molecules that are known to interface with immune cells and discuss potential strategies for their incorporation into biomaterial-based strategies aimed at culling inflammatory diseases. We hope this review will bridge the current findings in gut immunology, microbiology and biomaterials and spark further investigation into this emerging field. STATEMENT OF SIGNIFICANCE: Despite its tremendous potential to culminate into revolutionary therapeutics, the synergy between immunology, microbiology, and biomaterials has only been explored at a superficial level. Strategic incorporation of biomaterial-based technologies may be necessary to fully characterize and capitalize on the rapidly growing repertoire of immunomodulatory molecules derived from commensal microbes. Bioengineers may be able to combine state-of-the-art delivery platforms with immunomodulatory cues from commensals to provide a more holistic approach to combating inflammatory disease. This interdisciplinary approach could potentiate a neoteric field of research - "commensal-inspired" therapeutics with the promise of revolutionizing the treatment of inflammatory disease.

Aspirin Attenuates Cardiac Allograft Rejection by Inhibiting the Maturation of Dendritic Cells via the NF-κB Signaling Pathway

Background: Dendritic cells (DCs) serve as an important part of the immune system and play a dual role in immune response. Mature DCs can initiate immune response, while immature or semi-mature DCs induce immune hyporesponsiveness or tolerance. Previous studies have shown that aspirin can effectively inhibit the maturation of DCs. However, the protective effect of aspirin on acute cardiac allograft rejection has not been studied. The aim of this study was to elucidate the effect of aspirin exert on allograft rejection. Methods: The model of MHC-mismatched (BALB/c to B6 mice) heterotopic heart transplantation was established and administered intraperitoneal injection with aspirin. The severity of allograft rejection, transcriptional levels of cytokines, and characteristics of immune cells were assessed. Bone marrow-derived dendritic cells (BMDCs) were generated with or without aspirin. The function of DCs was determined via mixed lymphocyte reaction (MLR). The signaling pathway of DCs was detected by Western blotting. Results: Aspirin significantly prolonged the survival of cardiac allograft in mouse, inhibited the production of pro-inflammatory cytokines and the differentiation of effector T cells (Th1 and Th17), as well as promoted the regulatory T cells (Treg). The maturation of DCs in the spleen was obviously suppressed with aspirin treatment. In vitro, aspirin decreased the activation of NF-κB signaling of DCs, as well as impeded MHCII and co-stimulatory molecules (CD80, CD86, and CD40) expression on DCs. Moreover, both the pro-inflammatory cytokines and function of DCs were suppressed by aspirin. Conclusion: Aspirin inhibits the maturation of DCs through the NF-κB signaling pathway and attenuates acute cardiac allograft rejection.

Overexpression of miR-223 Promotes Tolerogenic Properties of Dendritic Cells Involved in Heart Transplantation Tolerance by Targeting Irak1

Dendritic cells (DCs) are key mediators of transplant rejection. Numerous factors have been identified that regulate transplant immunopathology by modulating the function of DCs. Among these, microRNAs (miRNAs), small non-coding RNA molecules, have received much attention. The miRNA miR-223 is very highly expressed and tightly regulated in hematopoietic cells. It plays an important role in modulating the immune response by regulating neutrophils and macrophages, and its dysregulation contributes to multiple types of immune diseases. However, the role of miR-223 in immune rejection is unclear. Here, we observed expression of miR-223 in patients and mice who had undergone heart transplantation and found that it increased in the serum of both, and also in DCs from the spleens of recipient mice, although it was unchanged in splenic T cells. We also found that miR-223 expression decreased in lipopolysaccharide-stimulated DCs. Increasing the level of miR-223 in DCs promoted polarization of DCs toward a tolerogenic phenotype, which indicates that miR-223 can attenuate activation and maturation of DCs. MiR-223 effectively induced regulatory T cells (Tregs) by inhibiting the function of antigen-presenting DCs. In addition, we identified Irak1 as a miR-223 target gene and an essential regulator of DC maturation. In mouse allogeneic heterotopic heart transplantation models, grafts survived longer and suffered less immune cell infiltration in mice with miR-223-overexpressing immature (im)DCs. In the miR-223-overexpressing imDC recipients, T cells from spleen differentiated into Tregs, and the level of IL-10 in heart grafts was markedly higher than that in the control group. In conclusion, miR-223 regulates the function of DCs via Irak1, differentiation of T cells into Tregs, and secretion of IL-10, thereby suppressing allogeneic heart graft rejection.

Role of IL-6 in dendritic cell functions

Dendritic cells (DCs) are efficient antigen-presenting cells that serve as a link between the innate and adaptive immune systems. These cells are broadly involved in cellular and humoral immune responses by presenting antigens to initiate T cell reactions, cytokine and chemokine secretion, T cell differentiation and expansion, B cell activation and regulation, and the mediation of immune tolerance. The functions of DCs depend on their activation status, which is defined by the stages of maturation, phenotype differentiation, and migration ability, among other factors. IL-6 is a soluble mediator mainly produced by a variety of immune cells, including DCs, that exerts pleiotropic effects on immune and inflammatory responses through interaction with specific receptors expressed on the surface of target cells. Here, we review the role of IL-6, when generated in an inflammatory context or as derived from DCs, in modulating the biologic function and activation status of DCs and emphasize the importance of searching for novel strategies to target the IL-6/IL-6 signaling pathway as a means to diminish the inflammatory activity of DCs in immune response or to prime the immunogenic activity of DCs in immunosuppressive conditions.

Tryptophan and Its Metabolites in Lung Cancer: Basic Functions and Clinical Significance

Lung cancer is the most lethal malignancy worldwide. Recently, it has been recognized that metabolic reprogramming is a complex and multifaceted factor, contributing to the process of lung cancer. Tryptophan (Try) is an essential amino acid, and Try and its metabolites can regulate the progression of lung cancer. Here, we review the pleiotropic functions of the Try metabolic pathway, its metabolites, and key enzymes in the pathogenic process of lung cancer, including modulating the tumor environment, promoting immune suppression, and drug resistance. We summarize the recent advance in therapeutic drugs targeting the Try metabolism and kynurenine pathway and their clinical trials.

Immunomodulatory Role and Therapeutic Potential of Non-Coding RNAs Mediated by Dendritic Cells in Autoimmune and Immune Tolerance-Related Diseases

Dendritic cells (DCs) are professional antigen-presenting cells that act as a bridge between innate immunity and adaptive immunity. After activation, DCs differentiate into subtypes with different functions, at which point they upregulate co-stimulatory molecules and produce various cytokines and chemokines. Activated DCs also process antigens for presentation to T cells and regulate the differentiation and function of T cells to modulate the immune state of the body. Non-coding RNAs, RNA transcripts that are unable to encode proteins, not only participate in the pathological mechanisms of autoimmune-related diseases but also regulate the function of immune cells in these diseases. Accumulating evidence suggests that dysregulation of non-coding RNAs contributes to DC differentiation, functions, and so on, consequently producing effects in various autoimmune diseases. In this review, we summarize the main non-coding RNAs (miRNAs, lncRNAs, circRNAs) that regulate DCs in pathological mechanisms and have tremendous potential to give rise to novel therapeutic targets and strategies for multiple autoimmune diseases and immune tolerance-related diseases.

Donor-derived regulatory dendritic cell infusion results in host cell cross-dressing and T cell subset changes in prospective living donor liver transplant recipients

Regulatory dendritic cells (DCreg) promote transplant tolerance following their adoptive transfer in experimental animals. We investigated the feasibility, safety, fate, and impact on host T cells of donor monocyte-derived DCreg infused into prospective, living donor liver transplant patients, 7 days before transplantation. The DCreg expressed a tolerogenic gene transcriptional profile, high cell surface programed death ligand-1 (PD-L1):CD86 ratios, high IL-10/no IL-12 productivity and poor ability to stimulate allogeneic T cell proliferation. Target DCreg doses (range 2.5-10 × 10⁶ cells/kg) were achieved in all but 1 of 15 recipients, with no infusion reactions. Following DCreg infusion, transiently elevated levels of donor HLA and immunoregulatory PD-L1, CD39, and CD73 were detected in circulating small extracellular vesicles. At the same time, flow and advanced image stream analysis revealed intact DCreg and "cross-dressing" of host DCs in blood and lymph nodes. PD-L1 co-localization with donor HLA was observed at higher levels than with recipient HLA. Between DCreg infusion and transplantation, T-bet^hi Eomes^hi memory CD8⁺ T cells decreased, whereas regulatory (CD25^hi CD127^- Foxp3⁺ ): T-bet^hi Eomes^hi CD8⁺ T cell ratios increased. Thus, donor-derived DCreg infusion may induce systemic changes in host antigen-presenting cells and T cells potentially conducive to modulated anti-donor immune reactivity at the time of transplant.

Multipotent adult progenitor cells induce regulatory T cells and promote their suppressive phenotype via TGFβ and monocyte-dependent mechanisms

Dysregulation of the immune system can initiate chronic inflammatory responses that exacerbate disease pathology. Multipotent adult progenitor cells (MAPC cells), an adult adherent bone-marrow derived stromal cell, have been observed to promote the resolution of uncontrolled inflammatory responses in a variety of clinical conditions including acute ischemic stroke, acute myocardial infarction (AMI), graft vs host disease (GvHD), and acute respiratory distress syndrome (ARDS). One of the proposed mechanisms by which MAPC cells modulate immune responses is via the induction of regulatory T cells (Tregs), however, the mechanism(s) involved remains to be fully elucidated. Herein, we demonstrate that, in an in vitro setting, MAPC cells increase Treg frequencies by promoting Treg proliferation and CD4⁺ T cell differentiation into Tregs. Moreover, MAPC cell-induced Tregs (miTregs) have a more suppressive phenotype characterized by increased expression of CTLA-4, HLA-DR, and PD-L1 and T cell suppression capacity. MAPC cells also promoted Treg activation by inducing CD45RA⁺ CD45RO⁺ transitional Tregs. Additionally, we identify transforming growth factor beta (TGFβ) as an essential factor for Treg induction secreted by MAPC cells. Furthermore, inhibition of indoleamine 2, 3-dioxygenase (IDO) resulted in decreased Treg induction by MAPC cells demonstrating IDO involvement. Our studies also show that CD14⁺ monocytes play a critical role in Treg induction by MAPC cells. Our study describes MAPC cell dependent Treg phenotypic changes and provides evidence of potential mechanisms by which MAPC cells promote Treg differentiation.

Dendritic Cell-Mediated Regulation of Liver Ischemia-Reperfusion Injury and Liver Transplant Rejection

Liver allograft recipients are more likely to develop transplantation tolerance than those that receive other types of organ graft. Experimental studies suggest that immune cells and other non-parenchymal cells in the unique liver microenvironment play critical roles in promoting liver tolerogenicity. Of these, liver interstitial dendritic cells (DCs) are heterogeneous, innate immune cells that appear to play pivotal roles in the instigation, integration and regulation of inflammatory responses after liver transplantation. Interstitial liver DCs (recruited in situ or derived from circulating precursors) have been implicated in regulation of both ischemia/reperfusion injury (IRI) and anti-donor immunity. Thus, livers transplanted from mice constitutively lacking DCs into syngeneic, wild-type recipients, display increased tissue injury, indicating a protective role of liver-resident donor DCs against transplant IRI. Also, donor DC depletion before transplant prevents mouse spontaneous liver allograft tolerance across major histocompatibility complex (MHC) barriers. On the other hand, mouse liver graft-infiltrating host DCs that acquire donor MHC antigen via "cross-dressing", regulate anti-donor T cell reactivity in association with exhaustion of graft-infiltrating T cells and promote allograft tolerance. In an early phase clinical trial, infusion of donor-derived regulatory DCs (DCreg) before living donor liver transplantation can induce alterations in host T cell populations that may be conducive to attenuation of anti-donor immune reactivity. We discuss the role of DCs in regulation of warm and liver transplant IRI and the induction of liver allograft tolerance. We also address design of cell therapies using DCreg to reduce the immunosuppressive drug burden and promote clinical liver allograft tolerance.

A myriad of roles of dendritic cells in atherosclerosis

Atherosclerosis is an inflammatory disease with break-down of homeostatic immune regulation of vascular tissues. As a critical initiator of host immunity, dendritic cells (DCs) have also been identified in the aorta of healthy individuals and atherosclerotic patients, whose roles in regulating arterial inflammation aroused great interest. Accumulating evidence has now pointed to the fundamental roles for DCs in every developmental stage of atherosclerosis due to their myriad of functions in immunity and tolerance induction, ranging from lipid uptake, efferocytosis and antigen presentation to pro- and anti-inflammatory cytokine or chemokine secretion. In this study we provide a timely summary of the published works in this field, and comprehensively discuss both the direct and indirect roles of DCs in atherogenesis. Understanding the pathogenic roles of DCs during the development of atherosclerosis in vascular tissues would certainly help to open therapeutic avenue to the treatment of cardiovascular diseases.