Immunomodulatory Bonds of the Partnership between Dendritic Cells and T Cells

Virus-like particle-based multipathogen vaccine of FMD and SVA elicits balanced and broad protective efficacy in mice and pigs

Inactivated vaccines lack the capability to serologically differentiate between infected and vaccinated animals, thereby impeding the effective eradication of pathogen. Conversely, vaccines based on virus-like particles (VLPs) emulate natural viruses in both size and antigenic structure, presenting a promising alternative to overcome these limitations. As the complexity of swine infectious diseases increases, the increase of vaccine types and doses may intensify the stress response. This exacerbation can lead to diminished productivity, failure of immunization, and elevated costs. Given the critical dynamics of co-infection and the clinically indistinguishable symptoms associated with foot-and-mouth disease virus (FMDV) and senecavirus A (SVA), there is a dire need for an efficacious intervention. To address these challenges, we developed a combined vaccine composed of three distinct VLPs, specifically designed to target SVA and FMDV serotypes O and A. Our research demonstrates that this trivalent VLP vaccine induces antigen-specific and robust serum antibody responses, comparable to those produced by the respective monovalent vaccines. Moreover, the immune sera from the combined VLP vaccine strongly neutralized FMDV type A and O, and SVA, with neutralization titers comparable to those of the individual vaccines, indicating a high level of immunogenic compatibility among the three VLP components. Importantly, the combined VLPs vaccines-immunized sera conferred efficient protection against single or mixed infections with FMDV type A and O, and SVA viruses in pigs. In contrast, individual vaccines could only protect pigs against homologous virus infections and not against heterologous challenges. This study presents a novel combined vaccines candidate against FMD and SVA, and provides new insights for the development of combination vaccines for other viral swine diseases.

Poly(allylamine)-tripolyphosphate polymeric nanoparticle as an NLRP3-dependent systemic adjuvant for the vaccine development

Nanotechnology plays a crucial role in vaccine development and provides the opportunity to design functional nanoparticles (Np) of different compositions, sizes, charges and surface properties for biomedical applications. The present study aims to evaluate a complex coacervate-like Np composed of poly(allylamine hydrochloride) (PAH) and tripolyphosphate (Tpp) as a safe vehicle and adjuvant for systemic vaccines. We investigated the activation of different antigen-presenting cells (APCs) with Np-PAH and its adjuvanticity in Balbc/c and different KO mice that were intraperitoneally immunized with Np-OVA. We found that Np-PAH increased the expression of CD86 and MHCII and promoted the production and secretion of interleukin-1β (IL-1β) and IL-18 through the inflammasome NLRP3 when macrophages and dendritic cells were co-incubated with LPS and Np-PAH. We evidenced an unconventional IL-1β release through the autophagosome pathway. The inhibition of autophagy with 3-methyladenine reduced the LPS/Np-PAH-induced IL-1β secretion. Additionally, our findings showed that the systemic administration of mice with Np-OVA triggered a significant induction of serum OVA-specific IgG and IgG2a, an increased secretion of IFN-γ by spleen cells, and high frequencies of LT CD4 + IFN-γ + and LT CD8 + IFN-γ + . In conclusion, our findings show that PAH-based Np promoted the inflammasome activation of innate cells with Th1-dependent adjuvant properties, making them valuable for formulating of novel preventive or therapeutic vaccines for infectious and non-infectious diseases.

Emerging T cell immunoregulatory mechanisms in multiple sclerosis and Alzheimer's disease

Multiple sclerosis (MS) and Alzheimer's disease (AD) are neuroinflammatory and neurodegenerative diseases with considerable socioeconomic impacts but without definitive treatments. AD and MS have multifactorial pathogenesis resulting in complex cognitive and neurologic symptoms and growing evidence also indicates key functions of specific immune cells. Whereas relevant processes dependent on T cells have been elucidated in both AD and MS, mechanisms that can control such immune responses still remain elusive. Here, a brief overview of select recent findings clarifying immunomodulatory mechanisms specifically induced by tolerogenic dendritic cells to limit the activation and functions of neurodegenerative T cells is presented. These insights could become a foundation for new cutting-edge research as well as therapeutic strategies.

Mesenchymal stromal cell derived extracellular vesicles as a therapeutic tool: immune regulation, MSC priming, and applications to SLE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a dysfunction of the immune system. Mesenchymal stromal cell (MSCs) derived extracellular vesicles (EVs) are nanometer-sized particles carrying a diverse range of bioactive molecules, such as proteins, miRNAs, and lipids. Despite the methodological disparities, recent works on MSC-EVs have highlighted their broad immunosuppressive effect, thus driving forwards the potential of MSC-EVs in the treatment of chronic diseases. Nonetheless, their mechanism of action is still unclear, and better understanding is needed for clinical application. Therefore, we describe in this review the diverse range of bioactive molecules mediating their immunomodulatory effect, the techniques and possibilities for enhancing their immune activity, and finally the potential application to SLE.

Augmenting regulatory T cells: new therapeutic strategy for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune condition marked by inflammation of the joints, degradation of the articular cartilage, and bone resorption. Recent studies found the absolute and relative decreases in circulating regulatory T cells (Tregs) in RA patients. Tregs are a unique type of cells exhibiting immunosuppressive functions, known for expressing the Foxp3 gene. They are instrumental in maintaining immunological tolerance and preventing autoimmunity. Increasing the absolute number and/or enhancing the function of Tregs are effective strategies for treating RA. This article reviews the studies on the mechanisms and targeted therapies related to Tregs in RA, with a view to provide better ideas for the treatment of RA.

Helios as a Potential Biomarker in Systemic Lupus Erythematosus and New Therapies Based on Immunosuppressive Cells

The Helios protein (encoded by the IKZF2 gene) is a member of the Ikaros transcription family and it has recently been proposed as a promising biomarker for systemic lupus erythematosus (SLE) disease progression in both mouse models and patients. Helios is beginning to be studied extensively for its influence on the T regulatory (Treg) compartment, both CD4+ Tregs and KIR+/Ly49+ CD8+ Tregs, with alterations to the number and function of these cells correlated to the autoimmune phenomenon. This review analyzes the most recent research on Helios expression in relation to the main immune cell populations and its role in SLE immune homeostasis, specifically focusing on the interaction between T cells and tolerogenic dendritic cells (tolDCs). This information could be potentially useful in the design of new therapies, with a particular focus on transfer therapies using immunosuppressive cells. Finally, we will discuss the possibility of using nanotechnology for magnetic targeting to overcome some of the obstacles related to these therapeutic approaches.

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.

TLR9 and STING agonists cooperatively boost the immune response to SARS-CoV-2 RBD vaccine through an increased germinal center B cell response and reshaped T helper responses

Vaccines are a powerful medical intervention for preventing epidemic diseases. Efficient inactivated or protein vaccines typically rely on an effective adjuvant to elicit an immune response and boost vaccine activity. In this study, we investigated the adjuvant activities of combinations of Toll-like receptor 9 (TLR9) and stimulator of interferon genes (STING) agonists in a SARS-CoV-2 receptor binding domain protein vaccine. Adjuvants formulated with a TLR9 agonist, CpG-2722, with various cyclic dinucleotides (CDNs) that are STING agonists increased germinal center B cell response and elicited humoral immune responses in immunized mice. An adjuvant containing CpG-2722 and 2'3'-c-di-AM(PS)2 effectively boosted the immune response to both intramuscularly and intranasally administrated vaccines. Vaccines adjuvanted with CpG-2722 or 2'3'-c-di-AM(PS)2 alone were capable of inducing an immune response, but a cooperative adjuvant effect was observed when both were combined. CpG-2722 induced antigen-dependent T helper (Th)1 and Th17 responses, while 2'3'-c-di-AM(PS)2 induced a Th2 response. The combination of CpG-2722 and 2'3'-c-di-AM(PS)2 generated a distinct antigen-dependent Th response profile characterized by higher Th1 and Th17, but lower Th2 responses. In dendritic cells, CpG-2722 and 2'3'-c-di-AM(PS)2 showed a cooperative effect on inducing expression of molecules critical for T cell activation. CpG-2722 and 2'3'-c-di-AM(PS)2 have distinct cytokine inducing profiles in different cell populations. The combination of these two agonists enhanced the expression of cytokines for Th1 and Th17 responses and suppressed the expression of cytokines for Th2 response in these cells. Thus, the antigen-dependent Th responses observed in the animals immunized with different vaccines were shaped by the antigen-independent cytokine-inducing profiles of their adjuvant. The expanded targeting cell populations, the increased germinal center B cell response, and reshaped T helper responses are the molecular bases for the cooperative adjuvant effect of the combination of TLR9 and STING agonists.

Activation, Amplification, and Ablation as Dynamic Mechanisms of Dendritic Cell Maturation

T cell responses to cognate antigens crucially depend on the specific functionality of dendritic cells (DCs) activated in a process referred to as maturation. Maturation was initially described as alterations of the functional status of DCs in direct response to multiple extrinsic innate signals derived from foreign organisms. More recent studies, conducted mainly in mice, revealed an intricate network of intrinsic signals dependent on cytokines and various immunomodulatory pathways facilitating communication between individual DCs and other cells for the orchestration of specific maturation outcomes. These signals selectively amplify the initial activation of DCs mediated by innate factors and dynamically shape DC functionalities by ablating DCs with specific functions. Here, we discuss the effects of the initial activation of DCs that crucially includes the production of cytokine intermediaries to collectively achieve amplification of the maturation process and further precise sculpting of the functional landscapes among DCs. By emphasizing the interconnectedness of the intracellular and intercellular mechanisms, we reveal activation, amplification, and ablation as the mechanistically integrated components of the DC maturation process.

Life and death of tolerogenic dendritic cells

In contrast to conventional dendritic cells (cDCs) that are constantly exposed to microbial signals at anatomical barriers, cDCs in systemic lymphoid organs are sheltered from proinflammatory stimulation in the steady state but respond to inflammatory signals by gaining specific immune functions in a process referred to as maturation. Recent findings show that, during maturation, a population of systemic tolerogenic cDCs undergoes an acute tumor necrosis factor α (TNFα)-mediated cell death, resulting in the loss of tolerance-inducing capacity. This tolerogenic cDC population is restored upon return to the homeostatic baseline. We propose that such a dynamic reshaping of cDC populations becomes the foundation of a novel framework for maintaining tolerance at the steady state while being conducive to unhampered initiation of immune responses under proinflammatory conditions.

Association between increased peripheral blood CD86-positive plasmacytoid dendritic cells and immune-related adverse events in patients with non-small cell lung cancer

The occurrence of immune-related adverse events (irAEs) after immune checkpoint inhibitors (ICIs) is unpredictable. Profiles of peripheral blood mononuclear cells (PBMCs) represent the host immune system and have the potential to predict irAEs. We analyzed PBMC subsets using multicolor flow cytometry before and at weeks 2 and 8 after the start of ICIs in patients with non-small cell lung cancer. Sixteen eligible patients were evaluated. The irAEs occurred in 6 patients (37.5%): diarrhea in 2, diarrhea and a rash in 1, pituitary dysfunction in 1, cholangitis in 1, and pneumonitis in 1. Patients experiencing irAEs had higher levels of CD86⁺plasmacytoid dendritic cells (pDCs) at the baseline and weeks 2 and 8 after the ICIs than those not experiencing irAEs (p = 0.005, 0.038, and 0.050, respectively). In patients experiencing irAEs, the levels of CD86⁺pDCs significantly decreased at weeks 2 and 8 compared to the baseline (p = 0 .034 and 0.025, respectively) but did not change in those not experiencing irAEs. The levels of other PBMC subsets were not significantly associated with irAEs. Higher levels of natural killer (NK) cells were significantly associated with an overall objective response (p = 0.024). In conclusion, higher levels of CD86⁺pDCs at the baseline and a reduction in those levels 2 and 8 weeks after ICIs were associated with the occurrence of irAEs. Higher levels of NK cells were associated with an objective response to ICIs. Evaluation of PBMCs may help to predict the efficacy and safety of ICIs.

Ox40-Cre-mediated deletion of BRD4 reveals an unexpected phenotype of hair follicle stem cells in alopecia

BRD4 is a bromodomain extraterminal domain family member and functions primarily as a chromatin reader regulating genes involved in cell-fate decisions. Here, we bred Brd4fl/fl Ox40-Cre mice in which Brd4 was conditionally deleted in OX40-expressing cells to examine the role of BRD4 in regulating immune responses. We found that the Brd4fl/fl Ox40-Cre mice developed profound alopecia and dermatitis, while other organs and tissues were not affected. Surprisingly, lineage-tracing experiments using the Rosa26fl/fl-Yfp mice identified a subset of hair follicle stem cells (HFSCs) that constitutively express OX40, and deletion of Brd4 specifically in such HFSCs resulted in cell death and a complete loss of skin hair growth. We also found that death of HFSCs triggered massive activation of the intradermal γδ T cells, which induced epidermal hyperplasia and dermatitis by producing the inflammatory cytokine IL-17. Interestingly, deletion of Brd4 in Foxp3+ Tregs, which also constitutively express OX40, compromised their suppressive functions, and this, in turn, contributed to the enhanced activation of γδ T cells, as well as the severity of dermatitis and hair follicle destruction. Thus, our data demonstrate an unexpected role of BRD4 in regulating skin follicle stem cells and skin inflammation.

Indoleamine 2,3-dioxygenase 1 signaling orchestrates immune tolerance in Echinococcus multilocularis-infected mice

The cestode Echinococcus multilocularis larva infection causes lethal zoonotic alveolar echinococcosis (AE), a disease posing a great threat to the public health worldwide. This persistent hepatic tumor-like disease in AE patients has been largely attributed to aberrant T cell responses, of which Th1 responses are impeded, whilst Th2 and regulatory T cell responses are elevated, creating an immune tolerogenic microenvironment in the liver. However, the immune tolerance mechanisms are not fully understood. Dendritic cells (DCs) are key cellular components in facilitating immune tolerance in chronic diseases, including AE. Here, we demonstrate that indoleamine 2,3-dioxygenase 1-deficient (IDO1-/-) mice display less severe AE as compared to wild-type (WT) mice during the infection. Mechanistically, IDO1 prevents optimal T cells responses by programming DCs into a tolerogenic state. Specifically, IDO1 prevents the maturation and migration potential of DCs, as shown by the significantly enhanced expression of the antigen-presenting molecule (MHC II), costimulatory molecules (CD80 and CD86), and chemokine receptors (CXCR4 and CCR7) in infected IDO1-/- mice as compared to infected wild-type mice. More importantly, the tolerogenic phenotype of DCs is partly reverted in IDO1-/- mice, as indicated by enhanced activation, proliferation, and differentiation of both CD4+ and CD8+ - T cells upon infection with Echinococcus multilocularis, in comparison with WT mice. Interestingly, in absence of IDO1, CD4+ T cells are prone to differentiate to effector memory cells (CD44+CD62L-); in contrast, CD8+ T cells are highly biased to the central memory phenotype (CD44+CD62L+). Overall, these data are the first to demonstrate the essential role of IDO1 signaling in inducing immunosuppression in mice infected with Echinococcus multilocularis.

Autologous blood extracellular vesicles and specific CD4+ T-cell co-activation

Extracellular vesicles (EVs), which are generated by cell membrane budding in diverse cells, are present in variable numbers in the blood. An immunoregulatory role has been demonstrated principally for heterologous EVs, but the function of the EVs present naturally in blood remains unknown. We hypothesize that these autologous EVs might also modulate the phenotype and function of immune system cells, especially CD4⁺ T lymphocytes (TLs), as previously described for heterologous EVs. Several membranes and soluble immunoregulatory molecules were studied after the treatment of CD4⁺ TLs with autologous EVs. No direct activation was detected with autologous EVs, contrasting with the findings for heterologous EVs. However, following treatment with autologous EVs, a soluble form of CD27 (sCD27) was detected. sCD27 is strongly associated with lymphoproliferation. Autologous EVs have been shown to increase TL proliferation only after T-cell receptor (TcR) engagement due to polyclonal or specific-antigen stimulation. Our results therefore suggest that the EVs present in the blood have an immunomodulatory role different from that of heterologous EVs. These findings should be taken into account in future studies, particularly those focusing on infectious diseases, autotransfusion or doping practices.

Effect of BCG HSP70 Gene Transfection on Dendritic Cells Derived From Bone Marrow in Children With Acute Leukemia

OBJECTIVES

In this study, immature dendritic cells (imDCs) were transfected with the Bacillé Calmette-Guérin (BCG) heat shock protein 70 (HSP70) gene to investigate the impact on the maturity and function of imDCs from the bone marrow of pediatric patients with acute leukemia.

MATERIALS AND METHODS

Bone marrow mononuclear cells were isolated from pediatric patients with acute lymphoblastic leukemia who had achieved complete remission at least 6 months prior. The recombinant vector pDisplay-HSP70 was transfected into imDCs. The test groups included 5 subgroups: imDCs (imDCs without special processing), imDC-neos (imDCs transfected with the pDisplay vector), HSP70 (imDCs transfected with the pDisplay-HSP70 vector), tumor necrosis factor α (TNF-α) (imDCs induced with rhTNF-α), and HSP70+TNF-α. Mature dendritic cells (mDCs) from different groups (HSP70, TNF-α, and HSP70+TNF-α) and T cells were cultured. An equal number of lymphocytes and mDCs were used as controls. The proliferation indices of T cells and the cytokine contents (interleukin-12 and interferon-γ) were determined.

RESULTS

The HSP70 group and the TNF-α group expressed higher levels of HLA-DR, CD80, and CD86 but lower levels than the HSP70+TNF-α group; there was no significant difference between the HSP70 group and the TNF-α group. The combination of HSP70 and TNF-α induced the highest levels of interleukin-12 and interferon-γ.

CONCLUSIONS

The outcomes of this study indicated that gene transfection with BCG HSP70 evidently promoted imDC maturity and the antitumor effects of mDC-mediated T cells. It could serve as a candidate gene-modified cell vaccine for tumor immunotherapy.

Immune-Cell-Derived Exosomes for Cancer Therapy

Exosomes are a type of extracellular vesicles secreted by cells in normal or pathological conditions for cell-cell communication. With immunomodulatory characteristics and potential therapeutic properties, immune-cell-derived exosomes play an important role in cancer therapy. They express various antigens on their surface, which can be employed for antigen presentation, immunological activation, and metabolic regulation, leading to the killing of cancerous cells. In addition, immune-cell-derived exosomes have received extensive attention as a drug delivery platform in effective antitumor therapy due to their excellent biocompatibility, low immunogenicity, and high loading capacity. In this review, the biological and therapeutic characteristics of immune-cell-derived exosomes are comprehensively outlined. The antitumor mechanism of exosomes secreted by immune cells, including macrophages, dendritic cells, T cells, B cells, and natural killer cells, are systematically summarized. Moreover, the applications of immune-cell-derived exosomes as nanocarriers to transport antitumor agents (chemotherapeutic drugs, genes, proteins, etc.) are discussed. More importantly, the existing challenges of immune-cell-derived exosomes are pointed out, and their antitumor potentials are also discussed.

HSV-1 Infection of Epithelial Dendritic Cells Is a Critical Strategy for Interfering with Antiviral Immunity

Herpes simplex virus type 1 (HSV-1), an α subgroup member of the human herpesvirus family, infects cells via the binding of its various envelope glycoproteins to cellular membrane receptors, one of which is herpes virus entry mediator (HVEM), expressed on dendritic cells. Here, HVEM gene-deficient mice were used to investigate the immunologic effect elicited by the HSV-1 infection of dendritic cells. Dendritic cells expressing the surface marker CD11c showed an abnormal biological phenotype, including the altered transcription of various immune signaling molecules and inflammatory factors associated with innate immunity after viral replication. Furthermore, the viral infection of dendritic cells interfered with dendritic cell function in the lymph nodes, where these cells normally play roles in activating the T-cell response. Additionally, the mild clinicopathological manifestations observed during the acute phase of HSV-1 infection were associated with viral replication in dendritic cells.

TNF-α sculpts a maturation process in vivo by pruning tolerogenic dendritic cells

It remains unclear how the pro-immunogenic maturation of conventional dendritic cells (cDCs) abrogates their tolerogenic functions. Here, we report that the loss of tolerogenic functions depends on the rapid death of BTLAhi cDC1s, which, in the steady state, are present in systemic peripheral lymphoid organs and promote tolerance that limits subsequent immune responses. A canonical inducer of maturation, lipopolysaccharide (LPS), initiates a burst of tumor necrosis factor alpha (TNF-α) production and the resultant acute death of BTLAhi cDC1s mediated by tumor necrosis factor receptor 1. The ablation of these individual tolerogenic cDCs is amplified by TNF-α produced by neighboring cells. This loss of tolerogenic cDCs is transient, accentuating the restoration of homeostatic conditions through biological turnover of cDCs in vivo. Therefore, our results reveal that the abrogation of tolerogenic functions during an acute immunogenic maturation depends on an ablation of the tolerogenic cDC population, resulting in a dynamic remodeling of the cDC functional landscape.

Variegated Outcomes of T Cell Activation by Dendritic Cells in the Steady State

Conventional dendritic cells (cDC) control adaptive immunity by sensing damage- and pathogen-associated molecular patterns and then inducing defined differentiation programs in T cells. Nevertheless, in the absence of specific proimmunogenic innate signals, generally referred to as the steady state, cDC also activate T cells to induce specific functional fates. Consistent with the maintenance of homeostasis, such specific outcomes of T cell activation in the steady state include T cell clonal anergy, deletion, and conversion of peripheral regulatory T cells (pTregs). However, the robust induction of protolerogenic mechanisms must be reconciled with the initiation of autoimmune responses and cancer immunosurveillance that are also observed under homeostatic conditions. Here we review the diversity of fates and functions of T cells involved in the opposing immunogenic and tolerogenic processes induced in the steady state by the relevant mechanisms of systemic cDC present in murine peripheral lymphoid organs.

Applications of Antibody-Based Antigen Delivery Targeted to Dendritic Cells In Vivo

Recombinant immunoglobulins, derived from monoclonal antibodies recognizing the defined surface epitopes expressed on dendritic cells, have been employed for the past two decades to deliver antigens to dendritic cells in vivo, serving as critical tools for the investigation of the corresponding T cell responses. These approaches originated with the development of the recombinant chimeric antibody against a multilectin receptor, DEC-205, which is present on subsets of murine and human conventional dendritic cells. Following the widespread application of antigen targeting through DEC-205, similar approaches then utilized other epitopes as entry points for antigens delivered by specific antibodies to multiple types of dendritic cells. Overall, these antigen-delivery methodologies helped to reveal the mechanisms underlying tolerogenic and immunogenic T cell responses orchestrated by dendritic cells. Here, we discuss the relevant experimental strategies as well as their future perspectives, including their translational relevance.

Non-severe burn injury increases cancer incidence in mice and has long-term impacts on the activation and function of T cells

Background

Recent evidence suggests that burn patients are at increased risk of hospital admission for infection, mental health conditions, cardiovascular disease and cancer for many years after discharge for the burn injury itself. Burn injury has also been shown to induce sustained immune system dysfunction. This change to immune function may contribute to the increased risk of chronic disease observed. However, the mechanisms that disrupt long-term immune function in response to burn trauma, and their link to long-term morbidity, remain unknown. In this study we investigated changes to immune function after burn injury using a murine model of non-severe injury.

Methods

An established mouse model of non-severe burn injury (full thickness burn equivalent to 8% total body surface area) was used in combination with an orthotopic model of B16 melanoma to investigate the link between burns and cancer. Considering that CD8⁺ T cells are important drivers of effective tumour suppression in this model, we also investigated potential dysregulation of this immune population using mouse models of burn injury in combination with herpes simplex virus infection. Flow cytometry was used to detect and quantify cell populations of interest and changes in immune function.

Results

We demonstrate that 4 weeks after a non-severe burn injury, mice were significantly more susceptible to tumour development than controls using an orthotopic model of B16 melanoma. In addition, our results reveal that CD8⁺ T cell expansion, differentiation and memory potential is significantly impaired at 1 month post-burn.

Conclusions

Our data suggests that CD8⁺ T cell-mediated immunity may be dysfunctional for a sustained period after even non-severe burn injury. Further studies in patients to validate these findings may support clinical intervention to restore or protect immunity in patients after burn injury and reduce the increased risk of secondary morbidities observed.

Regulatory T cells in ischemic stroke

Recent evidence shows that when ischemic stroke (IS) occurs, the BBB would be destructed, thereby promoting the immune cells to migrate into the brain, suggesting that the immune responses can play a vital role in the pathology of IS. As an essential subpopulation of immunosuppressive T cells, regulatory T (Treg) cells are involved in maintaining immune homeostasis and suppressing immune responses in the pathophysiological conditions of IS. During the past decades, the regulatory role of Treg cells has attracted the interest of numerous researchers. However, whether they are beneficial or detrimental to the outcomes of IS remains controversial. Moreover, Treg cells exert distinctive effects in the different stages of IS. Therefore, it is urgent to elucidate how Treg cells modulate the immune responses induced by IS. In this review, we describe how Treg cells fluctuate and play a role in the regulation of immune responses after IS in both experimental animals and humans, and summarize their biological functions and mechanisms in both CNS and periphery. We also discuss how Treg cells participate in poststroke inflammation and immunodepression and the potential of Treg cells as a novel therapeutic approach.

Assessing and counteracting fibrosis is a cornerstone of the treatment of CKD secondary to systemic and renal limited autoimmune disorders

Chronic kidney disease (CKD) is an increasing cause of morbidity and mortality worldwide. Besides the higher prevalence of diabetes, hypertension and aging worldwide, immune mediated disorders remain an important cause of kidney disease and are especially prevalent in young adults. Regardless of the initial insult, final pathway to CKD and kidney failure is always the loss of normal tissue and fibrosis development, in which the dynamic equilibrium between extracellular matrix synthesis and degradation is disturbed, leading to excessive production and accumulation. During fibrosis, a multitude of cell types intervene at different levels, but myofibroblasts and inflammatory cells are considered critical in the process. They exert their effects through different molecular pathways, of which transforming growth factor β (TGF-β) has demonstrated to be of particular importance. Additionally, CKD itself promotes fibrosis due to the accumulation of toxins and hormonal changes, and proteinuria is simultaneously a manifestation of CKD and a specific driver of renal fibrosis. Pathways involved in renal fibrosis and CKD are closely interrelated, and although important advances have been made in our knowledge of them, it is still necessary to translate them into clinical practice. Given the complexity of this process, it is highly likely that its treatment will require a multi-target strategy to control the origin of the damage but also the mechanisms that perpetuate it. Fortunately, rapid technology development over the last years and new available drugs in the nephrologist's armamentarium give reasons for optimism that more personalized assistance for CKD and renal fibrosis will appear in the future.

Targeting cytokines and immune checkpoints in atherosclerosis with monoclonal antibodies

Over the past fifteen years, treatments using monoclonal antibodies specifically targeting cytokines have been developed to treat chronic inflammatory diseases, including rheumatoid arthritis or psoriasis, both associated with increased cardiovascular risk. The cardiovascular impact of these therapies allows us to validate the clinical relevance of the knowledge acquired from experimental studies about the role of cytokines in atherosclerosis. Several clinical studies have confirmed the protective effects of anti-TNFα and anti-IL-6R monoclonal antibodies against athero-thrombotic cardiovascular risk in patients with chronic inflammatory diseases. Yet, caution is needed since anti-TNFα treatment can aggravate chronic heart failure. More recently, the CANTOS study showed for the first time that an anti-inflammatory treatment using anti-IL-1β monoclonal antibody in coronary artery disease patients significantly reduced cardiovascular events. The effects of IL-23/IL-17 axis blockade on cardiovascular risk in patients with psoriasis or arthritis remain controversial. Several monoclonal antibodies targeting costimulatory molecules have also been developed, a direct way to confirm their involvement in atherothrombotic cardiovascular diseases. Blocking the CD28^-CD80/86 axis with Abatacept has been shown to reduce cardiovascular risk. In contrast, the treatment of cancer patients with antibodies blocking immune checkpoint inhibitory receptors, such as CTLA-4, PD1, or PDL1, could worsen the risk of atherothrombotic events. In the future, cardiologists will be increasingly solicited to assess the cardiovascular risk of patients suffering from chronic inflammatory diseases or cancer and participate in choosing the most appropriate treatment. At the same time, immunomodulatory approaches directly targeting cardiovascular diseases will be developed as a complement to the usual treatment 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.

Resveratrol pretreatment mitigates LPS-induced acute lung injury by regulating conventional dendritic cells' maturation and function

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a severe syndrome lacking efficient therapy and resulting in high morbidity and mortality. Although resveratrol (RES), a natural phytoalexin, has been reported to protect the ALI by suppressing the inflammatory response, the detailed mechanism of how RES affected the immune system is poorly studied. Pulmonary conventional dendritic cells (cDCs) are critically involved in the pathogenesis of inflammatory lung diseases including ALI. In this study, we aimed to investigate the protective role of RES via pulmonary cDCs in lipopolysaccharide (LPS)-induced ALI mice. Murine ALI model was established by intratracheally challenging with 5 mg/kg LPS. We found that RES pretreatment could mitigate LPS-induced ALI. Additionally, proinflammatory-skewed cytokines decreased whereas anti-inflammatory-related cytokines increased in bronchoalveolar lavage fluid by RES pretreatment. Mechanistically, RES regulated pulmonary cDCs' maturation and function, exhibiting lower level of CD80, CD86, major histocompatibility complex (MHC) II expression, and IL-10 secretion in ALI mice. Furthermore, RES modulated the balance between proinflammation and anti-inflammation of cDCs. Moreover, in vitro RES pretreatment regulated the maturation and function of bone marrow derived dendritic cells (BMDCs). Finally, the adoptive transfer of RES-pretreated BMDCs enhanced recovery of ALI. Thus, these data might further extend our understanding of a protective role of RES in regulating pulmonary cDCs against ALI.

Re-Programming Autoreactive T Cells Into T-Regulatory Type 1 Cells for the Treatment of Autoimmunity

Systemic delivery of peptide-major histocompatibility complex (pMHC) class II-based nanomedicines can re-program cognate autoantigen-experienced CD4+ T cells into disease-suppressing T-regulatory type 1 (TR1)-like cells. In turn, these TR1-like cells trigger the formation of complex regulatory cell networks that can effectively suppress organ-specific autoimmunity without impairing normal immunity. In this review, we summarize our current understanding of the transcriptional, phenotypic and functional make up of TR1-like cells as described in the literature. The true identity and direct precursors of these cells remain unclear, in particular whether TR1-like cells comprise a single terminally-differentiated lymphocyte population with distinct transcriptional and epigenetic features, or a collection of phenotypically different subsets sharing key regulatory properties. We propose that detailed transcriptional and epigenetic characterization of homogeneous pools of TR1-like cells will unravel this conundrum.

Interaction between HLA-G and NK cell receptor KIR2DL4 orchestrates HER2-positive breast cancer resistance to trastuzumab

Despite the successful use of the humanized monoclonal antibody trastuzumab (Herceptin) in the clinical treatment of human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer, the frequently occurring drug resistance remains to be overcome. The regulatory mechanisms of trastuzumab-elicited immune response in the tumor microenvironment remain largely uncharacterized. Here, we found that the nonclassical histocompatibility antigen HLA-G desensitizes breast cancer cells to trastuzumab by binding to the natural killer (NK) cell receptor KIR2DL4. Unless engaged by HLA-G, KIR2DL4 promotes antibody-dependent cell-mediated cytotoxicity and forms a regulatory circuit with the interferon-γ (IFN-γ) production pathway, in which IFN-γ upregulates KIR2DL4 via JAK2/STAT1 signaling, and then KIR2DL4 synergizes with the Fcγ receptor to increase IFN-γ secretion by NK cells. Trastuzumab treatment of neoplastic and NK cells leads to aberrant cytokine production characterized by excessive tumor growth factor-β (TGF-β) and IFN-γ, which subsequently reinforce HLA-G/KIR2DL4 signaling. In addition, TGF-β and IFN-γ impair the cytotoxicity of NK cells by upregulating PD-L1 on tumor cells and PD-1 on NK cells. Blockade of HLA-G/KIR2DL4 signaling improved the vulnerability of HER2-positive breast cancer to trastuzumab treatment in vivo. These findings provide novel insights into the mechanisms underlying trastuzumab resistance and demonstrate the applicability of combined HLA-G and PD-L1/PD-1 targeting in the treatment of trastuzumab-resistant breast cancer.

Pediatric Tumors-Mediated Inhibitory Effect on NK Cells: The Case of Neuroblastoma and Wilms' Tumors

Simple Summary

Neuroblastoma (NB) and Wilms’ tumor (WT) are the most common childhood solid extracranial tumors. The current treatments consist of a combination of surgery and chemotherapy or radiotherapy in high-risk patients. Such treatments are responsible for significant adverse events requiring long-term monitoring. Thus, a main challenge in NB and WT treatment is the development of novel therapeutic strategies to eliminate or minimize the adverse effects. The characterization of the immune environment could allow for the identification of new therapeutic targets. Herein, we described the interaction between these tumors and innate immune cells, in particular natural killer cells and monocytes. The detection of the immunosuppressive activity of specific NB and WT tumor cells on natural killer cells and on monocytes could offer novel cellular and molecular targets for an effective immunotherapy of NB and WT.

Abstract

Natural killer (NK) cells play a key role in the control of cancer development, progression and metastatic dissemination. However, tumor cells develop an array of strategies capable of impairing the activation and function of the immune system, including NK cells. In this context, a major event is represented by the establishment of an immunosuppressive tumor microenvironment (TME) composed of stromal cells, myeloid-derived suppressor cells, tumor-associated macrophages, regulatory T cells and cancer cells themselves. The different immunoregulatory cells infiltrating the TME, through the release of several immunosuppressive molecules or by cell-to-cell interactions, cause an impairment of the recruitment of NK cells and other lymphocytes with effector functions. The different mechanisms by which stromal and tumor cells impair NK cell function have been particularly explored in adult solid tumors and, in less depth, investigated and discussed in a pediatric setting. In this review, we will compare pediatric and adult solid malignancies concerning the respective mechanisms of NK cell inhibition, highlighting novel key data in neuroblastoma and Wilms’ tumor, two of the most frequent pediatric extracranial solid tumors. Indeed, both tumors are characterized by the presence of stromal cells acting through the release of immunosuppressive molecules. In addition, specific tumor cell subsets inhibit NK cell cytotoxic function by cell-to-cell contact mechanisms likely controlled by the transcriptional coactivator TAZ. These findings could lead to a more performant diagnostic approach and to the development of novel immunotherapeutic strategies targeting the identified cellular and molecular targets.

Resolvin E1 Regulates Th17 Function and T Cell Activation

Resolvin E1 (RvE1) is a specialized pro-resolving lipid mediator derived from eicosapentaenoic acid and plays a critical role in resolving inflammation and tissue homeostasis. T_h17 cells are a distinct group of T helper (T_h) cells with tissue-destructive functions in autoimmune and chronic inflammatory diseases via the secretion of IL-17. Dendritic cell (DC)-mediated antigen presentation regulates the T_h17-induced progression of inflammation and tissue destruction. In this study, we hypothesized that the RvE1 would restore homeostatic balance and inflammation by targeting the T_h17 function. We designed three experiments to investigate the impact of RvE1 on different phases of T_h17 response and the potential role of DCs: First CD4⁺ T cells were induced by IL-6/TGF_β to measure the effect of RvE1 on T_h17 differentiation in an inflammatory milieu. Second, we measured the impact of RvE1 on DC-stimulated T_h17 differentiation in a co-culture model. Third, we measured the effect of RvE1 on DC maturation. RvE1 blocked the CD25, CCR6 and IL-17 expression; IL-17, IL-21, IL-10, and IL-2 production, suggesting inhibition of T cell activation, T_h17 stimulation and chemoattraction. RvE1 also suppressed the activation of DCs by limiting their pro-inflammatory cytokine production. Our findings collectively demonstrated that the RvE1 targeted the T_h17 activation and the DC function as a potential mechanism for inflammatory resolution and acquired immune response.

Regulatory Dendritic Cells, T Cell Tolerance, and Dendritic Cell Therapy for Immunologic Disease

Dendritic cells (DC) are antigen-presenting cells that can communicate with T cells both directly and indirectly, regulating our adaptive immune responses against environmental and self-antigens. Under some microenvironmental conditions DC develop into anti-inflammatory cells which can induce immunologic tolerance. A substantial body of literature has confirmed that in such settings regulatory DC (DCreg) induce T cell tolerance by suppression of effector T cells as well as by induction of regulatory T cells (Treg). Many in vitro studies have been undertaken with human DCreg which, as a surrogate marker of antigen-specific tolerogenic potential, only poorly activate allogeneic T cell responses. Fewer studies have addressed the abilities of, or mechanisms by which these human DCreg suppress autologous effector T cell responses and induce infectious tolerance-promoting Treg responses. Moreover, the agents and properties that render DC as tolerogenic are many and varied, as are the cells’ relative regulatory activities and mechanisms of action. Herein we review the most current human and, where gaps exist, murine DCreg literature that addresses the cellular and molecular biology of these cells. We also address the clinical relevance of human DCreg, highlighting the outcomes of pre-clinical mouse and non-human primate studies and early phase clinical trials that have been undertaken, as well as the impact of innate immune receptors and symbiotic microbial signaling on the immunobiology of DCreg.

TGF-β1 Signaling: Immune Dynamics of Chronic Kidney Diseases

Chronic kidney disease (CKD) is a major cause of morbidity and mortality worldwide, imposing a great burden on the healthcare system. Regrettably, effective CKD therapeutic strategies are yet available due to their elusive pathogenic mechanisms. CKD is featured by progressive inflammation and fibrosis associated with immune cell dysfunction, leading to the formation of an inflammatory microenvironment, which ultimately exacerbating renal fibrosis. Transforming growth factor β1 (TGF-β1) is an indispensable immunoregulator promoting CKD progression by controlling the activation, proliferation, and apoptosis of immunocytes via both canonical and non-canonical pathways. More importantly, recent studies have uncovered a new mechanism of TGF-β1 for de novo generation of myofibroblast via macrophage-myofibroblast transition (MMT). This review will update the versatile roles of TGF-β signaling in the dynamics of renal immunity, a better understanding may facilitate the discovery of novel therapeutic strategies against CKD.

Urolithin A ameliorates experimental autoimmune encephalomyelitis by targeting aryl hydrocarbon receptor

Background

Urolithin A (URA) is an intestinal microbiota metabolic product from ellagitannin-containing foods with multiple biological activities. However, its role in autoimmune diseases is largely unknown. Here, for first time, we demonstrate the therapeutic effect of URA in an experimental autoimmune encephalomyelitis (EAE) animal model.

Methods

Therapeutic effect was evaluated via an active and passive EAE animal model in vivo. The function of URA on bone marrow-derived dendritic cells (BM-DCs), T cells, and microglia were tested in vitro.

Findings

Oral URA (25 mg/kg/d) suppressed disease progression at prevention, induction, and effector phases of preclinical EAE. Histological evaluation showed that significantly fewer inflammatory cells, decreased demyelination, lower numbers of M1-type microglia and activated DCs, as well as reduced infiltrating Th1/Th17 cells were present in the central nervous system (CNS) of the URA-treated group. URA treatment at 25 μM inhibited the activation of BM-DCs in vitro, restrained Th17 cell differentiation in T cell polarization conditions, and in a DC-CD4⁺ T cell co-culture system. Moreover, we confirmed URA inhibited pathogenicity of Th17 cells in adoptive EAE. Mechanism of URA action was directly targeting Aryl Hydrocarbon Receptor (AhR) and modulating the signaling pathways.

Interpretation

Collectively, our study offers new evidence that URA, as a human microbial metabolite, is valuable to use as a prospective therapeutic candidate for autoimmune diseases.

Human invariant natural killer T cells promote tolerance by preferential apoptosis induction of conventional dendritic cells

Graft-versus-host disease (GvHD) is a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. We recently showed in murine studies and in vitro human models that adoptively transferred invariant natural killer T (iNKT) cells protect from GvHD and promote graft-versus-leukemia effects. The cellular mechanisms underlying GvHD prevention by iNKT cells in humans, however, remain unknown. In order to study relevant cellular interactions, dendritic cells (DC) were either generated from monocytes or isolated directly from blood of healthy donors or GvHD patients and co-cultured in a mixed lymphocyte reaction (MLR) with T cells obtained from healthy donors or transplantation bags. Addition of culture-expanded iNKT cells to the MLR-induced DC apoptosis in a cell contact-dependent manner, thereby preventing T-cell activation and proliferation. Annexin V/propidium iodide staining and image stream assays showed that CD4⁺CD8^–, CD4^–CD8⁺ and double negative iNKT cells are similarly able to induce DC apoptosis. Further MLR assays revealed that conventional DC (cDC) but not plasmacytoid DC (pDC) could induce alloreactive T-cell activation and proliferation. Interestingly, cDC were also more susceptible to apoptosis induced by iNKT cells, which correlates with their higher CD1d expression, leading to a bias in favor of pDC. Remarkably, these results could also be observed in GvHD patients. We propose a new mechanism how ex vivo expanded human iNKT cells prevent alloreactivity of T cells. iNKT cells modulate T-cell responses by selective apoptosis of DC subsets, resulting in suppression of T-cell activation and proliferation while enabling beneficial immune responses through pDC.

Wilms' Tumor Primary Cells Display Potent Immunoregulatory Properties on NK Cells and Macrophages

The immune response plays a crucial defensive role in cancer growth and metastasis and is a promising target in different tumors. The role of the immune system in Wilm's Tumor (WT), a common pediatric renal malignancy, is still to be explored. The characterization of the immune environment in WT could allow the identification of new therapeutic strategies for targeting possible inhibitory mechanisms and/or lowering toxicity of the current treatments. In this study, we stabilized four WT primary cultures expressing either a blastematous (CD56+/CD133-) or an epithelial (CD56-/CD133+) phenotype and investigated their interactions with innate immune cells, namely NK cells and monocytes. We show that cytokine-activated NK cells efficiently kill WT cells. However, after co-culture with WT primary cells, NK cells displayed an impaired cytotoxic activity, decreased production of IFNγ and expression of CD107a, DNAM-1 and NKp30. Analysis of the effects of the interaction between WT cells and monocytes revealed their polarization towards alternatively activated macrophages (M2) that, in turn, further impaired NK cell functions. In conclusion, we show that both WT blastematous and epithelial components may contribute directly and indirectly to a tumor immunosuppressive microenvironment that is likely to play a role in tumor progression.

A Two-Step Process of Effector Programming Governs CD4+ T Cell Fate Determination Induced by Antigenic Activation in the Steady State

Various processes induce and maintain immune tolerance, but effector T cells still arise under minimal perturbations of homeostasis through unclear mechanisms. We report that, contrary to the model postulating primarily tolerogenic mechanisms initiated under homeostatic conditions, effector programming is an integral part of T cell fate determination induced by antigenic activation in the steady state. This effector programming depends on a two-step process starting with induction of effector precursors that express Hopx and are imprinted with multiple instructions for their subsequent terminal effector differentiation. Such molecular circuits advancing specific terminal effector differentiation upon re-stimulation include programmed expression of interferon-γ, whose production then promotes expression of T-bet in the precursors. We further show that effector programming coincides with regulatory conversion among T cells sharing the same antigen specificity. However, conventional type 2 dendritic cells (cDC2) and T cell functions of mammalian target of rapamycin complex 1 (mTORC1) increase effector precursor induction while decreasing the proportion of T cells that can become peripheral Foxp3⁺ regulatory T (pTreg) cells.

The mechanisms in the steady state that govern the formation of effector T cells with potentially autoimmune functions remain unclear. Opejin et al. reveal a two-step process starting with induction of effector precursors that express Hopx and are imprinted with multiple instructions for their subsequent terminal effector differentiation.

Dendritic Cells and Microglia Have Non-redundant Functions in the Inflamed Brain with Protective Effects of Type 1 cDCs

Brain CD11c⁺ cells share features with microglia and dendritic cells (DCs). Sterile inflammation increases brain CD11c⁺ cells, but their phenotype, origin, and functions remain largely unknown. We report that, after cerebral ischemia, microglia attract DCs to the inflamed brain, and astroglia produce Flt3 ligand, supporting development and expansion of CD11c⁺ cells. CD11c⁺ cells in the inflamed brain are a complex population derived from proliferating microglia and infiltrating DCs, including a major subset of OX40L⁺ conventional cDC2, and also cDC1, plasmacytoid, and monocyte-derived DCs. Despite sharing certain morphological features and markers, CD11c⁺ microglia and DCs display differential expression of pattern recognition receptors and chemokine receptors. DCs excel CD11c^- and CD11c⁺ microglia in the capacity to present antigen through MHCI and MHCII. Of note, cDC1s protect from brain injury after ischemia. We thus reveal aspects of the dynamics and functions of brain DCs in the regulation of inflammation and immunity.

Using Gene Editing Approaches to Fine-Tune the Immune System

Genome editing technologies not only provide unprecedented opportunities to study basic cellular system functionality but also improve the outcomes of several clinical applications. In this review, we analyze various gene editing techniques used to fine-tune immune systems from a basic research and clinical perspective. We discuss recent advances in the development of programmable nucleases, such as zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeat (CRISPR)-Cas-associated nucleases. We also discuss the use of programmable nucleases and their derivative reagents such as base editing tools to engineer immune cells via gene disruption, insertion, and rewriting of T cells and other immune components, such natural killers (NKs) and hematopoietic stem and progenitor cells (HSPCs). In addition, with regard to chimeric antigen receptors (CARs), we describe how different gene editing tools enable healthy donor cells to be used in CAR T therapy instead of autologous cells without risking graft-versus-host disease or rejection, leading to reduced adoptive cell therapy costs and instant treatment availability for patients. We pay particular attention to the delivery of therapeutic transgenes, such as CARs, to endogenous loci which prevents collateral damage and increases therapeutic effectiveness. Finally, we review creative innovations, including immune system repurposing, that facilitate safe and efficient genome surgery within the framework of clinical cancer immunotherapies.

Natural and Induced Tolerogenic Dendritic Cells

Dendritic cells (DCs) are highly susceptible to extrinsic signals that modify the functions of these crucial APCs. Maturation of DCs induced by diverse proinflammatory conditions promotes immune responses, but certain signals also induce tolerogenic functions in DCs. These "induced tolerogenic DCs" help to moderate immune responses such as those to commensals present at specific anatomical locations. However, also under steady-state conditions, some DCs are characterized by inherent tolerogenic properties. The immunomodulatory mechanisms constitutively present in such "natural tolerogenic DCs" help to promote tolerance to peripheral Ags. By extending tolerance initially established in the thymus, these functions of DCs help to regulate autoimmune and other immune responses. In this review we will discuss the mechanisms and functions of natural and induced tolerogenic DCs and offer further insight into how their possible manipulations may ultimately lead to more precise treatments for various immune-mediated conditions and diseases.

The immunomodulatory potentials of interleukin-27 in airway allergies

Allergic airway disorders such as asthma and allergic rhinitis are mainly caused by inhaled allergen-induced improper activation and responses of immune and non-immune cells. One important response is the production of IL-27 by macrophages and dendritic cells (DCs) during the early stage of airway allergies. IL-27 exerts powerful modulatory influences on the cells of innate immunity [eg neutrophils, eosinophils, mast cells, monocytes, macrophages, dendritic cells (DCs), innate lymphoid cells (ILCs), natural killer (NK) cells and NKT cells)] and adaptive immunity (eg Th1, Th2, Th9, Th17, regulatory T, CD8⁺ cytotoxic T and B cells). The IL-27-mediated signalling pathways may be modulated to attenuate asthma and allergic rhinitis. In this review, a comprehensive discussion concerning the roles carried out by IL-27 in asthma and allergic rhinitis was provided, while evidences are presented favouring the use of IL-27 in the treatment of airway allergies.

Past, Present, and Future of Anticancer Nanomedicine

This review aims to summarize the methods that have been used till today, highlight methods that are currently being developed, and predict the future roadmap for anticancer therapy. In the beginning of this review, established approaches for anticancer therapy, such as conventional chemotherapy, hormonal therapy, monoclonal antibodies, and tyrosine kinase inhibitors are summarized. To counteract the side effects of conventional chemotherapy and to increase limited anticancer efficacy, nanodrug- and stem cell-based therapies have been introduced. However, current level of understanding and strategies of nanodrug and stem cell-based therapies have limitations that make them inadequate for clinical application. Subsequently, this manuscript reviews methods with fewer side effects compared to those of the methods mentioned above which are currently being investigated and are already being applied in the clinic. The newer strategies that are already being clinically applied include cancer immunotherapy, especially T cell-mediated therapy and immune checkpoint inhibitors, and strategies that are gaining attention include the manipulation of the tumor microenvironment or the activation of dendritic cells. Tumor-associated macrophage repolarization is another potential strategy for cancer immunotherapy, a method which activates macrophages to immunologically attack malignant cells. At the end of this review, we discuss combination therapies, which are the future of cancer treatment. Nanoparticle-based anticancer immunotherapies seem to be effective, in that they effectively use nanodrugs to elicit a greater immune response. The combination of these therapies with others, such as photothermal or tumor vaccine therapy, can result in a greater anticancer effect. Thus, the future of anticancer therapy aims to increase the effectiveness of therapy using various therapies in a synergistic combination rather than individually.

Transcriptomic profiling of bovine blood dendritic cells and monocytes following TLR stimulation

Dendritic cells (DC) and monocytes are vital for the initiation of innate and adaptive immune responses. Recently, we identified bona fide DC subsets in blood of cattle, revealing subset- and species-specific transcription of toll-like receptors (TLR). In the present study, we analyzed phenotypic and transcriptional responses of bovine DC subsets and monocytes to in vitro stimulation with four to six different TLR ligands. Bovine DC subsets, especially plasmacytoid DC (pDC), showed a clear increase of CCR7, CD25, CD40, CD80, CD86, and MHC-II expression both on mRNA and protein level. Flow cytometric detection of p38 MAPK phosphorylation 15 min after stimulation confirmed activation of DC subsets and monocytes in accordance with TLR gene expression. Whole-transcriptome sequencing of sorted and TLR-stimulated subsets revealed potential ligand- and subset-specific regulation of genes associated with inflammation, T-cell co-stimulation, migration, metabolic reprogramming, and antiviral activity. Gardiquimod was found to evoke strong responses both in DC subsets and monocytes, while Poly(I:C) and CpG preferentially triggered responses in cDC1 and pDC, respectively. This in-depth analysis of ligand responsiveness is essential for the rational design of vaccine adjuvants in cattle, and provides a solid basis for comparative studies on DC and monocyte biology across species.

Targeting Dendritic Cells with Antigen-Delivering Antibodies for Amelioration of Autoimmunity in Animal Models of Multiple Sclerosis and Other Autoimmune Diseases

The specific targeting of dendritic cells (DCs) using antigen-delivering antibodies has been established to be a highly efficient protocol for the induction of tolerance and protection from autoimmune processes in experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS), as well as in some other animal disease models. As the specific mechanisms of such induced tolerance are being investigated, the newly gained insights may also possibly help to design effective treatments for patients. Here we review approaches applied for the amelioration of autoimmunity in animal models based on antibody-mediated targeting of self-antigens to DCs. Further, we discuss relevant mechanisms of immunological tolerance that underlie such approaches, and we also offer some future perspectives for the application of similar methods in certain related disease settings such as transplantation.

Dual Pro- and Anti-Inflammatory Features of Monocyte-Derived Dendritic Cells

The transcription factor β-catenin is able to induce tolerogenic/anti-inflammatory features in different types of dendritic cells (DCs). Monocyte-derived dendritic cells (moDCs) have been widely used in dendritic cell-based cancer therapy, but so far with limited clinical efficacy. We wanted to investigate the hypothesis that aberrant differentiation or induction of dual pro- and anti-inflammatory features may be β-catenin dependent in moDCs. β-catenin was detectable in both immature and lipopolysaccharide (LPS)-stimulated DCs. The β-catenin inhibitor ICG-001 dose-dependently increased the pro-inflammatory signature cytokine IL-12p70 and decreased the anti-inflammatory signature molecule IL-10. The β-catenin activator 6-bromoindirubin-3′-oxime (6-BIO) dose-dependently increased total and nuclear β-catenin, and this was associated with decreased IL-12p70, increased IL-10, and reduced surface expression of activation markers, such as CD80 and CD86, and increased expression of inhibitory markers, such as PD-L1. 6-BIO and ICG-001 competed dose-dependently regarding these features. Genome-wide mRNA expression analyses further underscored the dual development of pro- and anti-inflammatory features of LPS-matured moDCs and suggest a role for β-catenin inhibition in production of more potent therapeutic moDCs.

IL-33 induced airways inflammation is partially dependent on IL-9

Asthma is an inflammatory disease of the airways and numerous cytokines contribute to this pathogenesis. It is shown that challenge of airways with IL-33 induces asthma-like pathological changes in mice, but the possible downstream cytokines in this process remain to be characterised. To explore this, we compared changes in the airways of wildtype (WT) and IL-9 deficient mice challenged with IL-33. In line with previous report, per-nasal challenge of WT mice with IL-33 significantly increased the responsiveness of the airways along with infiltration of inflammatory cells, goblet cell hyperplasia, collagen deposition and smooth muscle hypertrophy, and the expression of cytokines compared with control group. Surprisingly, all of these pathological changes were significantly attenuated in IL-9 deficient mice following identical IL-33 challenge. These data suggest that IL-9 is one downstream cytokine relevant to the effects of IL-33 in asthmatic airways and consequently a potential therapeutic target for the treatment of asthma.

Tissue sodium content in patients with systemic lupus erythematosus: association with disease activity and markers of inflammation

OBJECTIVES

Sodium (Na⁺) is stored in the skin and muscle and plays an important role in immune regulation. In animal models, increased tissue Na⁺ is associated with activation of the immune system, and high salt intake exacerbates autoimmune disease and worsens hypertension. However, there is no information about tissue Na⁺ and human autoimmune disease. We hypothesized that muscle and skin Na⁺ content is (a) higher in patients with systemic lupus erythematosus (SLE) than in control subjects, and (b) associated with blood pressure, disease activity, and inflammation markers (interleukin (IL)-6, IL-10 and IL-17 A) in SLE.

METHODS

Lower-leg skin and muscle Na⁺ content was measured in 23 patients with SLE and in 28 control subjects using ²³Na⁺ magnetic resonance imaging. Demographic and clinical information was collected from interviews and chart review, and blood pressure was measured. Disease activity was assessed using the SLE Disease Activity Index (SLEDAI). Plasma inflammation markers were measured by multiplex immunoassay.

RESULTS

Muscle Na⁺ content was higher in patients with SLE (18.8 (16.7-18.3) mmol/L) than in control subjects (15.8 (14.7-18.3) mmol/L; p < 0.001). Skin Na⁺ content was also higher in SLE patients than in controls, but this difference was not statistically significant. Among patients with SLE, muscle Na⁺ was associated with SLEDAI and higher concentrations of IL-10 after adjusting for age, race, and sex. Skin Na⁺ was significantly associated with systolic blood pressure, but this was attenuated after covariate adjustment.

CONCLUSION

Patients with SLE had higher muscle Na⁺ content than control subjects. In patients with SLE, higher muscle Na⁺ content was associated with higher disease activity and IL-10 concentrations.

Endoplasmic Reticulum-Associated Degradation-Dependent Processing in Cross-Presentation and Its Potential for Dendritic Cell Vaccinations: A Review

While the success of dendritic cell (DC) vaccination largely depends on cross-presentation (CP) efficiency, the precise molecular mechanism of CP is not yet characterized. Recent research revealed that endoplasmic reticulum (ER)-associated degradation (ERAD), which was first identified as part of the protein quality control system in the ER, plays a pivotal role in the processing of extracellular proteins in CP. The discovery of ERAD-dependent processing strongly suggests that the properties of extracellular antigens are one of the keys to effective DC vaccination, in addition to DC subsets and the maturation of these cells. In this review, we address recent advances in CP, focusing on the molecular mechanisms of the ERAD-dependent processing of extracellular proteins. As ERAD itself and the ERAD-dependent processing in CP share cellular machinery, enhancing the recognition of extracellular proteins, such as the ERAD substrate, by ex vivo methods may serve to improve the efficacy of DC vaccination.

Peptides from allergenic lipocalins bind to formyl peptide receptor 3 in human dendritic cells to mediate TH2 immunity

BACKGROUND

How TH2-mediated allergic immune responses are induced is still under investigation.

OBJECTIVE

In an in vitro system we compared the effect of lipocalin allergens and nonallergenic homologues on human monocyte-derived dendritic cells (DCs) to investigate how they polarize naive CD4+ TH cells. Microarray data gained with these DCs showed a significant difference in expression of formyl peptide receptors (FPRs). Activation of FPR3 in human monocyte-derived DCs leads to inhibition of IL-12 production. Low concentrations of IL-12 during T-cell priming biases immune responses toward TH2. We hypothesize that binding of allergenic lipocalins to FPR3 might be a mechanism for induction of allergic immune responses.

METHODS

We examined whether lipocalins and FPR3 colocalize within the cells by using confocal microscopy. With calcium mobilization assays of FPR3-transfected HEK 293 cells, we measured FPR3 signaling in response to allergenic and nonallergenic lipocalins. Silencing of FPR3 in DCs and pretreatment with an antagonistic peptide were used to assess the function of FPR3 in TH2 induction.

RESULTS

FPR3 and lipocalins colocalize in the same vesicles in DCs. Cathepsin S-digested allergenic lipocalins, but not digestion products of nonallergenic homologues, activate FPR3 signaling. FPR3 silencing in DCs or pretreatment with an antagonistic peptide restores IL-12 and induces IL-10 expression by DCs treated with lipocalin allergens, attenuating the TH2 bias and inducing IL-10 production in cocultured TH cells.

CONCLUSION

We describe a novel molecular mechanism for induction of TH2-mediated allergic immune responses.