Tolerogenic dendritic cells

Induction of antigen-specific tolerance by nanobody-antigen adducts that target class-II major histocompatibility complexes

The association of autoimmune diseases with particular allellic products of the class-II major histocompatibility complex (MHCII) region implicates the presentation of the offending self-antigens to T cells. Because antigen-presenting cells are tolerogenic when they encounter an antigen under non-inflammatory conditions, the manipulation of antigen presentation may induce antigen-specific tolerance. Here, we show that, in mouse models of experimental autoimmune encephalomyelitis, type 1 diabetes and rheumatoid arthritis, the systemic administration of a single dose of nanobodies that recognize MHCII molecules and conjugated to the relevant self-antigen under non-inflammatory conditions confers long-lasting protection against these diseases. Moreover, co-administration of a nanobody-antigen adduct and the glucocorticoid dexamethasone, conjugated to the nanobody via a cleavable linker, halted the progression of established experimental autoimmune encephalomyelitis in symptomatic mice and alleviated their symptoms. This approach may represent a means of treating autoimmune conditions.

Ubiquitin Ligases CBL and CBL-B Maintain the Homeostasis and Immune Quiescence of Dendritic Cells

Dendritic cells (DCs) are composed of multiple lineages of hematopoietic cells and orchestrate immune responses upon detecting the danger and inflammatory signals associated with pathogen and damaged tissues. Under steady-state, DCs are maintained at limited numbers and the functionally quiescent status. While it is known that a fine balance in the DC homeostasis and activation status is also important to prevent autoimmune diseases and hyperinflammation, mechanisms that control DC development and activation under stead-state remain not fully understood. Here we show that DC-specific ablation of CBL and CBL-B (CBL^-/-CBL-B^-/-) leads to spontaneous liver inflammation and fibrosis and early death of the mice. The mutant mice have a marked expansion of classic CD8α⁺/CD103⁺ DCs (cDC1s) in peripheral lymphoid organs and the liver. These DCs exhibit atypical activation phenotypes characterized by an increased production of inflammatory cytokines and chemokines but not the cell surface MHC-II and costimulatory ligands. While the mutant mice also have massive T cell activation, lymphocytes are not required for the disease development. The CBL^-/-CBL-B^-/- mutation enhances FLT3-mTOR signaling, due to defective FLT3 ubiquitination and degradation. Blockade of FLT3-mTOR signaling normalizes the homeostasis of cDC1s and attenuates liver inflammation. Our result thus reveals a critical role of CBLs in the maintenance of DC homeostasis and immune quiescence. This regulation could be relevant to liver inflammatory diseases and fibrosis in humans.

Cyclosporine A, in Contrast to Rapamycin, Affects the Ability of Dendritic Cells to Induce Immune Tolerance Mechanisms

Following organ transplantation, it is essential that immune tolerance is induced in the graft recipient to reduce the risk of rejection and avoid complications associated with the long-term use of immunosuppressive drugs. Immature dendritic cells (DCs) are considered to promote transplant tolerance and may minimize the risk of graft rejection. The aim of the study was to evaluate the effects of immunosuppressive agents: rapamycin (Rapa) and cyclosporine A (CsA) on generation of human tolerogenic DCs (tolDCs) and also to evaluate the ability of these cells to induce mechanisms of immune tolerance. tolDCs were generated in the environment of Rapa or CsA. Next, we evaluated the effects of these agents on surface phenotypes (CD11c, MHC II, CD40, CD80, CD83, CD86, CCR7, TLR2, TLR4), cytokine production (IL-4, IL-6, IL-10, IL-12p70, TGF-β), phagocytic capacity and resistant to lipopolysaccharide activation of these DCs. Moreover, we assessed ability of such tolDCs to induce T cell activation and apoptosis, Treg differentiation and production of Th1- and Th2-characteristic cytokine profile. Data obtained in this study demonstrate that rapamycin is effective at generating maturation-resistant tolDCs, however, does not change the ability of these cells to induce mechanisms of immune tolerance. In contrast, CsA affects the ability of these cells to induce mechanisms of immune tolerance, but is not efficient at generating maturation-resistant tolDCs.

High-fat Diet Alters Male Seminal Plasma Composition to Impair Female Immune Adaptation for Pregnancy in Mice

Paternal experiences and exposures before conception can influence fetal development and offspring phenotype. The composition of seminal plasma contributes to paternal programming effects through modulating the female reproductive tract immune response after mating. To investigate whether paternal obesity affects seminal plasma immune-regulatory activity, C57Bl/6 male mice were fed an obesogenic high-fat diet (HFD) or control diet (CD) for 14 weeks. Although HFD consumption caused only minor changes to parameters of sperm quality, the volume of seminal vesicle fluid secretions was increased by 65%, and the concentrations and total content of immune-regulatory TGF-β isoforms were decreased by 75% to 80% and 43% to 55%, respectively. Mating with BALB/c females revealed differences in the strength and properties of the postmating immune response elicited. Transcriptional analysis showed >300 inflammatory genes were similarly regulated in the uterine endometrium by mating independently of paternal diet, and 13 were dysregulated by HFD-fed compared with CD-fed males. Seminal vesicle fluid factors reduced in HFD-fed males, including TGF-β1, IL-10, and TNF, were among the predicted upstream regulators of differentially regulated genes. Additionally, the T-cell response induced by mating with CD-fed males was blunted after mating with HFD-fed males, with 27% fewer CD4+ T cells, 26% fewer FOXP3+CD4+ regulatory T cells (Treg) cells, and 19% fewer CTLA4+ Treg cells, particularly within the NRP1+ thymic Treg cell population. These findings demonstrate that an obesogenic HFD alters the composition of seminal vesicle fluid and impairs seminal plasma capacity to elicit a favorable pro-tolerogenic immune response in females at conception.

Live Birth Rates after Active Immunization with Partner Lymphocytes

Although many potential causes have been established for recurrent implantation failure (RIF) and recurrent miscarriage (RM), about 50% of these remain idiopathic. Scientific research is focused on immunological risk factors. In the present study, we aim to evaluate live birth rates after immunization with paternal lymphocytes (lymphocyte immunotherapy (LIT)). This retrospective study consisted of 148 couples with a history of RM and/or RIF. The women underwent immunization with lymphocytes of their respective partners from November 2017 to August 2019. Fifty-five patients (43%) had live births. Stratified by indication (RM, RIF, combined), live birth rates in the RM and the combined group were significantly higher than that in the RIF group (53%, 59% and 33%, respectively, p = 0.02). The difference was especially noticeable during the first 90 days after immunization (conception rate leading to live births: 31%, 23% and 8% for RM, the combined group and RIF, respectively; p = 0.005), while there was no difference between groups during the later follow-up. LIT was associated with high live birth rates, especially in women with recurrent miscarriage. In view of the limited data from randomized studies, LIT cannot be recommended as routine therapy. However, it may be considered in individual cases.

GRAS-microparticle microarrays identify dendritic cell tolerogenic marker-inducing formulations

Microarrays, miniaturized platforms used for high-content studies, provide potential advantages over traditional in vitro investigation in terms of time, cost, and parallel analyses. Recently, microarrays have been leveraged to investigate immune cell biology by providing a platform with which to systematically investigate the effects of various agents on a wide variety of cellular processes, including those giving rise to immune regulation for application toward curtailing autoimmunity. A specific embodiment incorporates dendritic cells cultured on microarrays containing biodegradable microparticles. Such an approach allows immune cell and microparticle co-localization and release of compounds on small, isolated populations of cells, enabling a quick, convenient method to quantify a variety of cellular responses in parallel. In this study, the microparticle microarray platform was utilized to investigate a small library of sixteen generally regarded as safe (GRAS) compounds (ascorbic acid, aspirin, capsaicin, celastrol, curcumin, epigallocatechin-3-gallate, ergosterol, hemin, hydrocortisone, indomethacin, menadione, naproxen, resveratrol, retinoic acid, α-tocopherol, vitamin D3) for their ability to induce suppressive phenotypes in murine dendritic cells. Two complementary tolerogenic index ranking systems were proposed to summarize dendritic cell responses and suggested several lead compounds (celastrol, ergosterol, vitamin D3) and two secondary compounds (hemin, capsaicin), which warrant further investigation for applications toward suppression and tolerance.

Role of IL-37- and IL-37-Treated Dendritic Cells in Acute Coronary Syndrome

As a chronic inflammatory disease, atherosclerosis is a leading cause of morbidity and mortality in most countries. Inflammation is responsible for plaque instability and the subsequent onset of acute coronary syndrome (ACS), which is one of the leading causes of hospitalization. Therefore, exploring the potential mechanism underlying ACS is of considerable concern, and searching for alternative therapeutic targets is very urgent. Interleukin-37 (IL-37) inhibits the production of proinflammatory chemokines and cytokines and acts as a natural inhibitor of innate and adaptive immunity. Interestingly, our previous study with murine models showed that IL-37 alleviated cardiac remodeling and myocardial ischemia/reperfusion injury. Of note, our clinical study revealed that IL-37 is elevated and plays a beneficial role in patients with ACS. Moreover, dendritic cells (DCs) orchestrate both immunity and tolerance, and tolerogenic DCs (tDCs) are characterized by more secretion of immunosuppressive cytokines. As expected, IL-37-treated DCs are tolerogenic. Hence, we speculate that IL-37- or IL-37-treated DCs is a novel therapeutic possibility for ACS, and the precise mechanism of IL-37 requires further study.

Gold Nanoparticles: Multifaceted Roles in the Management of Autoimmune Disorders

Gold nanoparticles (GNPs) have been recently applied for various diagnostic and therapeutic purposes. The unique properties of these nanoparticles (NPs), such as relative ease of synthesis in various sizes, shapes and charges, stability, high drug-loading capacity and relative availability for modification accompanied by non-cytotoxicity and biocompatibility, make them an ideal field of research in bio-nanotechnology. Moreover, their potential to alleviate various inflammatory factors, nitrite species, and reactive oxygen production and the capacity to deliver therapeutic agents has attracted attention for further studies in inflammatory and autoimmune disorders. Furthermore, the characteristics of GNPs and surface modification can modulate their toxicity, biodistribution, biocompatibility, and effects. This review discusses in vitro and in vivo effects of GNPs and their functionalized forms in managing various autoimmune disorders (Ads) such as rheumatoid arthritis, type 1 diabetes, and multiple sclerosis.

Toll-like receptor-4 null mutation causes fetal loss and fetal growth restriction associated with impaired maternal immune tolerance in mice

Maternal immune adaptation to accommodate pregnancy depends on sufficient availability of regulatory T (Treg) cells to enable embryo implantation. Toll-like receptor 4 is implicated as a key upstream driver of a controlled inflammatory response, elicited by signals in male partner seminal fluid, to initiate expansion of the maternal Treg cell pool after mating. Here, we report that mice with null mutation in Tlr4 (Tlr4^−/−) exhibit impaired reproductive outcomes after allogeneic mating, with reduced pregnancy rate, elevated mid-gestation fetal loss, and fetal growth restriction, compared to Tlr4^+/+ wild-type controls. To investigate the effects of TLR4 deficiency on early events of maternal immune adaptation, TLR4-regulated cytokines and immune regulatory microRNAs were measured in the uterus at 8 h post-mating by qPCR, and Treg cells in uterus-draining lymph nodes were evaluated by flow cytometry on day 3.5 post-coitum. Ptgs2 encoding prostaglandin-endoperoxide synthase 2, cytokines Csf2, Il6, Lif, and Tnf, chemokines Ccl2, Cxcl1, Cxcl2, and Cxcl10, and microRNAs miR-155, miR-146a, and miR-223 were induced by mating in wild-type mice, but not, or to a lesser extent, in Tlr4^−/− mice. CD4⁺ T cells were expanded after mating in Tlr4^+/+ but not Tlr4^−/− mice, with failure to expand peripheral CD25⁺FOXP3⁺ NRP1⁻ or thymic CD25⁺FOXP3⁺ NRP1⁺ Treg cell populations, and fewer Treg cells expressed Ki67 proliferation marker and suppressive function marker CTLA4. We conclude that TLR4 is an essential mediator of the inflammation-like response in the pre-implantation uterus that induces generation of Treg cells to support robust pregnancy tolerance and ensure optimal fetal growth and survival.

Dendritic Cells and Antiphospholipid Syndrome: An Updated Systematic Review

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by autoreactive B and T cells against β2-glycoprotein I (B2GPI), with vascular thrombosis or obstetrical complications. Dendritic cells (DCs) are crucial in the generation of autoimmunity. Here, we conducted a comprehensive systematic review on the relationship between DC and APS. We performed a literature search of PubMed as of 26 March 2021. A total of 33 articles were extracted. DCs are pivotal in inducing inflammatory responses and orchestrating adaptive immunity. DCs contribute to the local inflammation regarding vascular thrombosis or obstetrical complications. Both B2GPI and antiphospholipid antibodies (aPL) can promote antigen presentation by DCs and the generation or maintenance of autoimmunity. In addition, plasmacytoid DC activation is enhanced by aPL, thereby augmenting the inflammatory response. In line with these findings, DC modulation appears promising as a future treatment for APS. In conclusion, our review indicated the crucial role of DCs in the pathogenesis of APS. Deeper understanding of the complex relationship would help in developing new treatment strategies.

Activation of Transcription Factor 4 in Dendritic Cells Controls Th1/Th17 Responses and Autoimmune Neuroinflammation

Dendritic cells (DCs) are professional APCs that play a crucial role in initiating robust immune responses against invading pathogens while inducing regulatory responses to the body's tissues and commensal microorganisms. A breakdown of DC-mediated immunological tolerance leads to chronic inflammation and autoimmune disorders. However, cell-intrinsic molecular regulators that are critical for programming DCs to a regulatory state rather than to an inflammatory state are not known. In this study, we show that the activation of the TCF4 transcription factor in DCs is critical for controlling the magnitude of inflammatory responses and limiting neuroinflammation. DC-specific deletion of TCF4 in mice increased Th1/Th17 responses and exacerbated experimental autoimmune encephalomyelitis pathology. Mechanistically, loss of TCF4 in DCs led to heightened activation of p38 MAPK and increased levels of proinflammatory cytokines IL-6, IL-23, IL-1β, TNF-α, and IL-12p40. Consistent with these findings, pharmacological blocking of p38 MAPK activation delayed experimental autoimmune encephalomyelitis onset and diminished CNS pathology in TCF4^ΔDC mice. Thus, manipulation of the TCF4 pathway in DCs could provide novel opportunities for regulating chronic inflammation and represents a potential therapeutic approach to control autoimmune neuroinflammation.

Simultaneous transduction of dendritic cells with A20 and BTLA genes stimulates the development of stable and efficient tolerogenic dendritic cells and induces regulatory T cells

BACKGROUND

This study investigated the potential of simultaneous overexpression of A20 and B- and T-lymphocyte attenuator (BTLA) genes in dendritic cells (DCs) to develop a tolerogenic phenotype in DCs and investigate their capabilities for induction of immunosuppression.

METHODS

Plasmid vectors were designed harboring A20, BTLA, and A20 + BTLA genes and were transfected to HEK 293T cells to produce lentiviruses. DCs were transduced by the gene carrying viruses and evaluated for the surface expression of MHCII, CD40, and CD86 molecules by flow-cytometry. The mRNA expression of A20, BTLA, and CCR7 were determined. Mixed-lymphocyte reaction was conducted to evaluate the T cell stimulation potency and ELISA was used to measure the production of IL-10, TGF-β, and TNF-α. The potential of DCs for migration to lymph nodes and Treg induction were assessed by in vivo experiments.

RESULTS

Transduction of DCs resulted in significantly decreased surface expression of CD40 and CD86 co-stimulators and upregulated A20, BTLA, and CCR7 mRNA expression. The IL-10 and TGF-β levels were enhanced significantly in the supernatant of LPS-treated DCs transduced with A20 + BTLA-containing virus group relative to the DCs transduced with pCDH vectors. DCs transduced with A20 + BTLA harboring vectors had higher migratory potential to mouse lymph nodes and caused the development of higher numbers of Treg cells compared with the DCs transduced with pCDH vectors.

CONCLUSIONS

Simultaneous overexpression of A20 and BTLA genes in DCs caused development of tolerogenic DCs with a promoted potential in induction of Treg cells, accompanied by remarkable stability after inflammatory stimulation. All these offer a promising potential of such DCs in treating autoimmune and inflammatory disorders.

DC-Derived Exosomes for Cancer Immunotherapy

As the initiators of adaptive immune responses, DCs play a central role in regulating the balance between CD8 T cell immunity versus tolerance to tumor antigens. Exploiting their function to potentiate host anti-tumor immunity, DC-based vaccines have been one of most promising and widely used cancer immunotherapies. However, DC-based cancer vaccines have not achieved the promised success in clinical trials, with one of the major obstacles being tumor-mediated immunosuppression. A recent discovery on the critical role of type 1 conventional DCs (cDC1s) play in cross-priming tumor-specific CD8 T cells and determining the anti-tumor efficacy of cancer immunotherapies, however, has highlighted the need to further develop and refine DC-based vaccines either as monotherapies or in combination with other therapies. DC-derived exosomes (DCexos) have been heralded as a promising alternative to DC-based vaccines, as DCexos are more resistance to tumor-mediated suppression and DCexo vaccines have exhibited better anti-tumor efficacy in pre-clinical animal models. However, DCexo vaccines have only achieved limited clinical efficacy and failed to induce tumor-specific T cell responses in clinical trials. The lack of clinical efficacy might be partly due to the fact that all current clinical trials used peptide-loaded DCexos from monocyte-derived DCs. In this review, we will focus on the perspective of expanding current DCexo research to move DCexo cancer vaccines forward clinically to realize their potential in cancer immunotherapy.

Type-2 dendritic cells mediate control of cytotoxic T cell-resistant tumors

Type 2 DCs (DC2s) comprise the majority of conventional DCs within most tumors; however, little is known about their ability to initiate and sustain antitumor immunity, as most studies have focused on antigen cross-presenting DC1s. Here, we report that DC2 infiltration identified by analysis of multiple human cancer data sets showed a significant correlation with survival across multiple human cancers, with the benefit being seen in tumors resistant to cytotoxic T cell control. Characterization of DC subtype infiltration into an immunotherapy-resistant model of breast cancer revealed that impairment of DC1s through 2 unique models resulted in enhanced DC2 functionality and improved tumor control. BATF3 deficiency depleted intratumoral DC1s, which led to increased DC2 lymph node migration and CD4⁺ T cell activation. Enhancing DC2 stimulatory potential by genetic deletion of Hsp90b1 (encoding molecular chaperon GP96) led to a similar enhancement of T cell immunity and improved survival in a spontaneous breast cancer model. These data highlight the therapeutic and prognostic potential of DC2s within checkpoint blockade–resistant tumors.

Precursor Abundance Influences Divergent Antigen-Specific CD8+ T Cell Responses after Yersinia pseudotuberculosis Foodborne Infection

Primary infection of C57BL/6 mice with the bacterial pathogen Yersinia pseudotuberculosis elicits an unusually large H-2K^b-restricted CD8⁺ T cell response to the endogenous and protective bacterial epitope YopE_69-77. To better understand the basis for this large response, the model OVA_257-264 epitope was inserted into YopE in Y. pseudotuberculosis and antigen-specific CD8⁺ T cells in mice were characterized after foodborne infection with the resulting strain. The epitope YopE_69-77 elicited significantly larger CD8⁺ T cell populations in the small intestine, mesenteric lymph nodes (MLNs), spleen, and liver between 7 and 30 days postinfection, despite residing in the same protein and having an affinity for H-2K^b similar to that of OVA_257-264. YopE-specific CD8⁺ T cell precursors were ∼4.6 times as abundant as OVA-specific precursors in the MLNs, spleens, and other lymph nodes of naive mice, explaining the dominance of YopE_69-77 over OVA_257-264 at early infection times. However, other factors contributed to this dominance, as the ratio of YopE-specific to OVA-specific CD8⁺ T cells increased between 7 and 30 days postinfection. We also compared the YopE-specific and OVA-specific CD8⁺ T cells generated during infection for effector and memory phenotypes. Significantly higher percentages of YopE-specific cells were characterized as short-lived effectors, while higher percentages of OVA-specific cells were memory precursor effectors at day 30 postinfection in spleen and liver. Our results suggest that a large precursor number contributes to the dominance and effector and memory functions of CD8⁺ T cells generated in response to the protective YopE_69-77 epitope during Y. pseudotuberculosis infection of C57BL/6 mice.

Glycoproteins Presenting Galactose and N-Acetylgalactosamine in Human Seminal Plasma as Potential Players Involved in Immune Modulation in the Fertilization Process

In light of recent research, there is increasing evidence showing that extracellular semen components have a significant impact on the immune reaction of the female partner, leading to the tolerogenic response enabling the embryo development and implantation as well as further progress of healthy pregnancy. Seminal plasma glycoproteins are rich in the unique immunomodulatory glycoepitopes that may serve as ligands for endogenous lectins that decorate the surface of immune cells. Such interaction may be involved in modulation of the maternal immune response. Among immunomodulatory glycans, Lewis type antigens have been of interest for at least two decades, while the importance of T/Tn antigens and related structures is still far from understanding. In the current work, we applied two plant lectins capable of distinguishing glycoepitopes with terminal GalNAc and Gal to identify glycoproteins that are their efficient carriers. By means of lectin blotting and lectin affinity chromatography followed by LC-MS, we identified lactotransferrin, prolactin inducible protein as well as fibronectin and semenogelins 1 and 2 as lectin-reactive. Net-O-glycosylation analysis results indicated that the latter three may actually carry T and/or Tn antigens, while in the case of prolactin inducible protein and lactotransferrin LacdiNAc and lactosamine glycoepitopes were more probable. STRING bioinformatics analysis linked the identified glycoproteins in the close network, indicating their involvement in immune (partially innate) processes. Overall, our research revealed potential seminal plasma ligands for endogenous Gal/GalNAc specific lectins with a possible role in modulation of maternal immune response during fertilization.

In Vivo Implications of Potential Probiotic Lactobacillus reuteri LR6 on the Gut and Immunological Parameters as an Adjuvant Against Protein Energy Malnutrition

The present study investigated the impact of probiotic Lactobacillus reuteri LR6 on the gut and systemic immunity using protein energy malnourished (PEM) murine model. Thirty male Swiss albino mice were divided into five groups: control (C), malnourished (M), probiotic fermented milk (PFM), skim milk (SM), and bacterial suspension (BS) with six mice per group. Group C was fed with conventional diet throughout the study while the other groups were fed with protein calorie restricted diet until the development of malnutrition. After development of malnutrition, group M was continued with the restricted diet while other groups were fed with re-nourished diet supplemented with PFM, SM, and BS for 1 week, respectively. Thereafter, mice were sacrificed and different histological, microbiological, and immunological parameters were studied. Probiotics feeding in PEM model as fermented product or bacterial suspension improved the intestinal health in terms of intact morphology of colonic crypts, normal goblet cells, and intact lamina propria with no inflammation in large intestine, absence of fibrosis, and no inflammation in spleen. The number of secretory IgA⁺ cells was significantly higher in group PFM and BS. Also, increase in the phagocytic percentage of the macrophages and bone marrow derived dendritic cells (DCs) were observed in the PFM and BS group in comparison to the group M. In comparison to the group M and SM, lactobacilli, bifidobacteria, and Firmicutes counts were significantly higher in the group PFM and BS. This study concludes that probiotic supplementation to re-nutrition diet could emerge as wonder therapeutics against PEM.

Polymeric nanoparticles containing rapamycin and autoantigen induce antigen-specific immunological tolerance for preventing vitiligo in mice

Vitiligo is an autoimmune disease in which pigment is lost in patches of the skin. CD4⁺ T cells are implicated in vitiligo while regulatory T cells (Tregs) could ameliorate vitiligo. Rapamycin together with autoantigen have been shown to induce immunological tolerance and promote Tregs in multiple autoimmune diseases. In the current study, we synthesized nanoparticles containing rapamycin and autoantigen HEL_46-61 (NP_{HEL46-61/Rapa}) and investigated their effects on vitiligo. We treated bone marrow-derived dendritic cells (BMDCs) from TrpHEL mice with NP_{HEL46-61/Rapa} and monitored the phenotype of BMDCs. We investigated the effects of NP_{HEL46-61/Rapa}-treated BMDCs on CD4⁺ T cell proliferation and differentiation. We administrated NP_{HEL46-61/Rapa} to TCR-TrpHEL mice and investigated the effects on vitiligo. We found that BMDCs can uptake the NP_{HEL46-61/Rapa}, which resulted in decreased expression of costimulation molecules CD80 and CD86 in BMDCs. BMDCs treated with NP_{HEL46-61/Rapa} suppressed antigen-specific CD4⁺ T cell proliferation while promoted the differentiation of these CD4⁺ T cell to Tregs in vitro. Administration of NP_{HEL46-61/Rapa} to TCR-TrpHEL mice ameliorated vitiligo, promoted Treg production, and suppressed IFN-γ and IL-6 production, while induced IL-10 production. Therefore, our study provides experimental evidence that nanoparticles containing rapamycin and autoantigen could induce antigen-specific immunological tolerance and prevent vitiligo.

Reactive oxygen species-responsive dendritic cell-derived exosomes for rheumatoid arthritis

Although tolerogenic dendritic cell-derived exosomes (TolDex) have emerged as promising therapeutics for rheumatoid arthritis (RA), their clinical applications have been hampered by their poor in vivo disposition after systemic administration. Herein, we report the development of stimuli-responsive TolDex that induces lesion-specific immunoregulation in RA. Responsiveness to reactive oxygen species (ROS), a physiological stimulus in the RA microenvironment, was conferred on TolDex by introducing a thioketal (TK) linker-embedded poly(ethylene glycol) (PEG) on TolDex surface via hydrophobic insertion. The detachment of PEG following overproduction of ROS facilitates the cellular uptake of ROS-responsive TolDex (TKDex) into activated immune cells. Notably, TolDex and TKDex downregulated CD40 in mature dendritic cells (mDCs) and regulated secretion of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin-6 (IL-6) at the cellular level. In the collagen-induced arthritis (CIA) mouse model, PEG prolonged the blood circulation of TKDex following intravenous administration and enhanced their accumulation in the joints. In addition, TKDex decreased IL-6, increased transforming growth factor-β, and induced the CD4⁺CD25⁺Foxp3⁺ regulatory T cells in CIA mice. Overall, ROS-responsive TolDex might have potential as therapeutic agents for RA. STATEMENT OF SIGNIFICANCE: Tolerogenic dendritic cell-derived exosomes (TolDex) are emerging immunoregulators of autoimmune diseases, including rheumatoid arthritis (RA). However, their lack of long-term stability and low targetability are still challenging. To overcome these issues, we developed reactive oxygen species (ROS)-responsive TolDex (TKDex) by incorporating the ROS-sensitive functional group-embedded poly(ethylene glycol) linker into the exosomal membrane of TolDex. Surface-engineered TKDex were internalized in mature DCs because of high ROS-sensitivity and enhanced accumulation in the inflamed joint in vivo. Further, for the first time, we investigated the potential mechanism of action of TolDex relevant to CD40 downregulation and attenuation of tumor necrosis factor (TNF)-α secretion. Our strategy highlighted the promising nanotherapeutic effects of stimuli-sensitive TolDex, which induces immunoregulation.

Determinants of resistance to VEGF-TKI and immune checkpoint inhibitors in metastatic renal cell carcinoma

Vascular endothelial growth factor tyrosine kinase inhibitors (VEGF-TKIs) have been the mainstay of treatment for patients with advanced renal cell carcinoma (RCC). Despite its early promising results in decreasing or delaying the progression of RCC in patients, VEGF-TKIs have provided modest benefits in terms of disease-free progression, as 70% of the patients who initially respond to the treatment later develop drug resistance, with 30% of the patients innately resistant to VEGF-TKIs. In the past decade, several molecular and genetic mechanisms of VEGF-TKI resistance have been reported. One of the mechanisms of VEGF-TKIs is inhibition of the classical angiogenesis pathway. However, recent studies have shown the restoration of an alternative angiogenesis pathway in modulating resistance. Further, in the last 5 years, immune checkpoint inhibitors (ICIs) have revolutionized RCC treatment. Although some patients exhibit potent responses, a non-negligible number of patients are innately resistant or develop resistance within a few months to ICI therapy. Hence, an understanding of the mechanisms of VEGF-TKI and ICI resistance will help in formulating useful knowledge about developing effective treatment strategies for patients with advanced RCC. In this article, we review recent findings on the emerging understanding of RCC pathology, VEGF-TKI and ICI resistance mechanisms, and potential avenues to overcome these resistance mechanisms through rationally designed combination therapies.

Intestinal cDC1 drive cross-tolerance to epithelial-derived antigen via induction of FoxP3+CD8+ Tregs

Although CD8⁺ T cell tolerance to tissue-specific antigen (TSA) is essential for host homeostasis, the mechanisms underlying peripheral cross-tolerance and whether they may differ between tissue sites remain to be fully elucidated. Here, we demonstrate that peripheral cross-tolerance to intestinal epithelial cell (IEC)-derived antigen involves the generation and suppressive function of FoxP3⁺CD8⁺ T cells. FoxP3⁺CD8⁺ T_reg generation was dependent on intestinal cDC1, whose absence led to a break of tolerance and epithelial destruction. Mechanistically, intestinal cDC1-derived PD-L1, TGFβ, and retinoic acid contributed to the generation of gut-tropic CCR9⁺CD103⁺FoxP3⁺CD8⁺ T_regs Last, CD103-deficient CD8⁺ T cells lacked tolerogenic activity in vivo, indicating a role for CD103 in FoxP3⁺CD8⁺ T_reg function. Our results describe a role for FoxP3⁺CD8⁺ T_regs in cross-tolerance in the intestine for which development requires intestinal cDC1.

Peptide allergen-specific immunotherapy for allergic airway diseases-State of the art

Allergen-specific immunotherapy (AIT) is the only means of altering the natural immunological course of allergic diseases and achieving long-term remission. Pharmacological measures are able to suppress the immune response and/or ameliorate the symptoms but there is a risk of relapse soon after these measures are withdrawn. Current AIT approaches depend on the administration of intact allergens, often comprising crude extracts of the allergen. We propose that the challenges arising from current approaches, including the risk of serious side-effects, burdensome duration of treatment, poor compliance and high cost, are overcome by application of peptides based on CD4⁺ T cell epitopes rather than whole allergens. Here we describe evolving approaches, summarize clinical trials involving peptide AIT in allergic rhinitis and asthma, discuss the putative mechanisms involved in their action, address gaps in evidence and propose future directions for research and clinical development.

Advancement of antigen-specific immunotherapy: knowledge transfer between allergy and autoimmunity

Targeted restoration of immunological tolerance to self-antigens or innocuous environmental allergens represents the ultimate aim of treatment options in autoimmune and allergic disease. Antigen-specific immunotherapy (ASI) is the only intervention that has proven disease-modifying efficacy as evidenced by induction of long-term remission in a number of allergic conditions. Mounting evidence is now indicating that specific targeting of pathogenic T cells in autoinflammatory and autoimmune settings enables effective restoration of immune homeostasis between effector and regulatory cells and alters the immunological course of disease. Here, we discuss the key lessons learned during the development of antigen-specific immunotherapies and how these can be applied to inform future interventions. Armed with this knowledge and current high-throughput technology to track immune cell phenotype and function, it may no longer be a matter of ‘if’ but ‘when’ this ultimate aim of targeted tolerance restoration is realised.

CD47 Deficiency Ameliorates Ocular Autoimmune Inflammation

Autoimmune uveitis is a sight-threatening ocular inflammatory condition in which the retina and uveal tissues become a target of autoreactive immune cells. The CD47 is a ubiquitously expressed transmembrane protein which plays multiple roles in fundamental cellular functions including phagocytosis, proliferation, and adhesion. Signal regulatory protein alpha (SIRPα), one of the CD47 ligands, is predominantly expressed in myeloid lineage cells such as dendritic cells (DCs) or macrophages, and CD47-SIRPα signaling pathway is implicated in the development of autoimmune diseases. Our current study demonstrates how CD47 depletion is effective in the prevention of experimental autoimmune uveitis (EAU), an animal model of human autoimmune uveitis, in animals deficient of CD47 (CD47-/- ). Systemic suppression of SIRPα+ DCs in animals deficient in CD47 resulted in the inability of autoreactive CD4+ T cells to develop, which is crucial to induction of EAU. Of interest, retinal microglia, the resident immune cell of the retina, express SIRPα, however these cells were not operative in EAU suppression in response to CD47 depletion. These results identify CD47 as a significant regulator in the development of SIRPα+ DCs that is vital to disease induction in EAU.

Current advances in using tolerogenic dendritic cells as a therapeutic alternative in the treatment of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease characterized by the destruction of insulin-producing β-cells of the pancreatic islets by autoreactive T cells, leading to high blood glucose levels and severe long-term complications. The typical treatment indicated in T1D is exogenous insulin administration, which controls glucose levels; however, it does not stop the autoimmune process. Various strategies have been implemented aimed at stopping β-cell destruction, such as cellular therapy. Dendritic cells (DCs) as an alternative in cellular therapy have gained great interest for autoimmune disease therapy due to their plasticity to acquire immunoregulatory properties both in vivo and in vitro, performing functions such as anti-inflammatory cytokine secretion and suppression of autoreactive lymphocytes, which are dependent of their tolerogenic phenotype, displayed by features such as semimature phenotype, low surface expression of stimulatory molecules to prime T cells, as well as the elevated expression of inhibitory markers. DCs may be obtained and propagated easily in optimal amounts from peripheral blood or bone marrow precursors, such as monocytes or hematopoietic stem cells, respectively; therefore, various protocols have been established for tolerogenic (tol)DCs manufacturing for therapeutic research in the treatment of T1D. In this review, we address the current advances in the use of tolDCs for T1D therapy, encompassing protocols for their manufacturing, the data obtained from preclinical studies carried out, and the status of clinical research evaluating the safety, feasibility, and effectiveness of tolDCs.

Differential Metabolome in Rheumatoid Arthritis: a Brief Perspective

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) is a chronic autoimmune, inflammatory disease of the synovium that affects the movable joints. It develops due to the infiltration and invasion of the synovial joints by immune cells. Metabolism is anabolic or catabolic chemical reactions occurring in a cell. The biochemical pathways in synovial and immune cells are altered affecting the downstream metabolite formation. Changes in the metabolite levels alter signaling cascades which further intensify the disease. Despite current knowledge of metabolomics, there remain certain features that need to be elucidated to correlate the differential metabolite levels with RA.

RECENT FINDINGS

Metabolite profiling can be used to find altered patterns of metabolites in RA. Glucose, lipid, amino acid, and estrogen metabolism are the key pathways that are altered and contribute to the aggravation of RA. The altered metabolic pathways involved in different cells in RA results in complex interactions between metabolites and biomacromolecules; thus, it generates autoantigens. Moreover, understanding the correlation between differential metabolites and disease severity might help reveal potential new biomarkers and therapeutic targets for RA pathogenesis. So, considering the multi-faceted role of altered metabolites in the pathogenesis of RA, metabolic pathways of different cells are needed to be studied for a better understanding of their functions in the disease and thus, improving the present therapeutic strategies.

Select hyperactivating NLRP3 ligands enhance the TH1- and TH17-inducing potential of human type 2 conventional dendritic cells

The detection of microorganisms and danger signals by pattern recognition receptors on dendritic cells (DCs) and the consequent formation of inflammasomes are pivotal for initiating protective immune responses. Although the activation of inflammasomes leading to secretion of the cytokine IL-1β is typically accompanied by pyroptosis (an inflammatory form of lytic programmed cell death), some cells can survive and exist in a state of hyperactivation. Here, we found that the conventional type 2 DC (cDC2) subset is the major human DC subset that is transcriptionally and functionally poised for inflammasome formation and response without pyroptosis. When cDC2 were stimulated with ligands that relatively weakly activated the inflammasome, the cells did not enter pyroptosis but instead secreted IL-12 family cytokines and IL-1β. These cytokines induced prominent T helper type 1 (T_H1) and T_H17 responses that were superior to those seen in response to Toll-like receptor (TLR) stimulation alone or to stronger, classical inflammasome ligands. These findings not only define the human cDC2 subpopulation as a prime target for the treatment of inflammasome-dependent inflammatory diseases but may also inform new approaches for adjuvant and vaccine development.

In Sickness and in Health: The Immunological Roles of the Lymphatic System

The lymphatic system plays crucial roles in immunity far beyond those of simply providing conduits for leukocytes and antigens in lymph fluid. Endothelial cells within this vasculature are distinct and highly specialized to perform roles based upon their location. Afferent lymphatic capillaries have unique intercellular junctions for efficient uptake of fluid and macromolecules, while expressing chemotactic and adhesion molecules that permit selective trafficking of specific immune cell subsets. Moreover, in response to events within peripheral tissue such as inflammation or infection, soluble factors from lymphatic endothelial cells exert “remote control” to modulate leukocyte migration across high endothelial venules from the blood to lymph nodes draining the tissue. These immune hubs are highly organized and perfectly arrayed to survey antigens from peripheral tissue while optimizing encounters between antigen-presenting cells and cognate lymphocytes. Furthermore, subsets of lymphatic endothelial cells exhibit differences in gene expression relating to specific functions and locality within the lymph node, facilitating both innate and acquired immune responses through antigen presentation, lymph node remodeling and regulation of leukocyte entry and exit. This review details the immune cell subsets in afferent and efferent lymph, and explores the mechanisms by which endothelial cells of the lymphatic system regulate such trafficking, for immune surveillance and tolerance during steady-state conditions, and in response to infection, acute and chronic inflammation, and subsequent resolution.

Priming of myelin-specific T cells in the absence of dendritic cells results in accelerated development of Experimental Autoimmune Encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an established animal model of multiple sclerosis (MS). Inflammatory CD4+ T cell responses directed against CNS antigens, including myelin proteolipid protein (PLP), are key mediators of EAE. Dendritic cells (DCs) are critical for the induction of T cell responses against infectious agents. However, the importance of DCs in priming self-reactive CD4+ T cells in autoimmune disease such as MS has been unclear. To determine the requirement of DCs in PLP-specific CD4+ T cell responses and EAE, we genetically deleted CD11c+ DCs in PLP T cell receptor (TCR) transgenic SJL mice constitutively. DC deficiency did not impair the development, selection or the pathogenic function of PLP-specific CD4+ T cells in these mice, and resulted in accelerated spontaneous EAE compared to DC sufficient controls. In addition, using a genetic approach to ablate DCs conditionally in SJL mice, we show that CD11c+ DCs were dispensable for presenting exogenous or endogenous myelin antigen to PLP-specific T cells and for promoting pro-inflammatory T cell responses and severe EAE. Our findings demonstrate that constitutive or conditional ablation of CD11c+ DCs diminished self-tolerance to PLP autoantigen. They further show that in the absence of DCs, non-DCs can efficiently present CNS myelin antigens such as PLP to self-reactive T cells, resulting in accelerated onset of spontaneous or induced EAE.

Dendritic Cell Tumor Vaccination via Fc Gamma Receptor Targeting: Lessons Learned from Pre-Clinical and Translational Studies

Despite significant recent improvements in the field of immunotherapy, cancer remains a heavy burden on patients and healthcare systems. In recent years, immunotherapies have led to remarkable strides in treating certain cancers. However, despite the success of checkpoint inhibitors and the advent of cellular therapies, novel strategies need to be explored to (1) improve treatment in patients where these approaches fail and (2) make such treatments widely and financially accessible. Vaccines based on tumor antigens (Ag) have emerged as an innovative strategy with the potential to address these areas. Here, we review the fundamental aspects relevant for the development of cancer vaccines and the critical role of dendritic cells (DCs) in this process. We first offer a general overview of DC biology and routes of Ag presentation eliciting effective T cell-mediated immune responses. We then present new therapeutic avenues specifically targeting Fc gamma receptors (FcγR) as a means to deliver antigen selectively to DCs and its effects on T-cell activation. We present an overview of the mechanistic aspects of FcγR-mediated DC targeting, as well as potential tumor vaccination strategies based on preclinical and translational studies. In particular, we highlight recent developments in the field of recombinant immune complex-like large molecules and their potential for DC-mediated tumor vaccination in the clinic. These findings go beyond cancer research and may be of relevance for other disease areas that could benefit from FcγR-targeted antigen delivery, such as autoimmunity and infectious diseases.

Manipulating antigen presentation for antigen-specific immunotherapy of autoimmune diseases

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Specific immunotherapy is the ‘holy grail’ for treatment of autoimmunity.

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Antigens are delivered by either direct or indirect presentation mechanisms.

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Liver APC and steady state DC mediate distinct forms of immune regulation.

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Tr1 cell induction involves epigenetic modification of tolerance associated genes.

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Trials reveal that antigen-specific immunotherapy can control autoimmune diseases.

Current treatments for autoimmune diseases do not address the immune pathology underlying their initiation and progression and too often rely on non-specific immunosuppressive drugs for control of symptoms. Antigen-specific immunotherapy aims to induce tolerance selectively among the cells causing the disease while leaving the rest of the adaptive immune system capable of protecting against infectious diseases and cancers. Here we describe how novel approaches for antigen-specific immunotherapy are designed to manipulate antigen presentation and promote tolerance to specific self-antigens. This analysis points to liver antigen presenting cells, targeted by carrier particles, and steady-state dendritic cells, to which antigen-processing independent T-cell epitopes (apitopes) bind directly, as the principal targets for antigen-specific immunotherapy. Delivery of antigens to these cells holds great promise for effective control of this rapidly expanding group of diseases.

Role of immune regulatory cells in breast cancer: Foe or friend?

Breast cancer (BC) is the most common cancer among women between the ages of 20 and 50, affecting more than 2.1 million people and causing the annual death of more than 627,000 women worldwide. Based on the available knowledge, the immune system and its components are involved in the pathogenesis of several malignancies, including BC. Cancer immunobiology suggests that immune cells can play a dual role and induce anti-tumor or immunosuppressive responses, depending on the tumor microenvironment (TME) signals. The most important effector immune cells with anti-tumor properties are natural killer (NK) cells, B, and T lymphocytes. On the other hand, immune and non-immune cells with regulatory/inhibitory phenotype, including regulatory T cells (Tregs), regulatory B cells (Bregs), tolerogenic dendritic cells (tDCs), tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), myeloid-derived suppressor cells (MDSCs), mesenchymal stem cells (MSCs), and regulatory natural killer cells (NKregs), can promote the growth and development of tumor cells by inhibiting anti-tumor responses, inducing angiogenesis and metastasis, as well as the expression of inhibitory molecules and suppressor mediators of the immune system. However, due to the complexity of the interaction and the modification in the immune cells' phenotype and the networking of the immune responses, the exact mechanism of action of the immunosuppressive and regulatory cells is not yet fully understood. This review article reviews the immune responses involved in BC as well as the role of regulatory and inhibitory cells in the pathogenesis of the disease. Finally, therapeutic approaches based on inhibition of immunosuppressive responses derived from regulatory cells are discussed.

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

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

Amelioration of Graft-versus-Host Disease by Exopolysaccharide from a Commensal Bacterium

Acute graft-versus-host disease (aGvHD) is a severe, often lethal, complication of hematopoietic stem cell transplantation, and although prophylactic regimens are given as standard pretransplantation therapy, up to 60% of these patients develop aGvHD, and require additional immunosuppressive intervention. We treated mice with a purified probiotic molecule, exopolysaccharide (EPS) from Bacillus subtilis, shortly before and after induction of aGvHD and found that, whereas only 10% of control mice survived to day 80, 70% of EPS-treated mice survived to 80 d. EPS treatment of donor-only mice resulted in ∼60% survival. Using a biosensor mouse model to assess inflammation in live mice during aGvHD, we found that EPS prevented the activation of alloreactive donor T cells. In vitro, EPS did not affect T cells directly but, instead, induced bone marrow-derived dendritic cells (BMDCs) that displayed characteristics of inhibitory dendritic cells (DCs). Development of these BMDCs required TLR4 signaling through both MyD88 and TRIF pathways. Using BMDCs derived from IDO knockout mice, we showed that T cell inhibition by EPS-treated BMDCs was mediated through the suppressive effects of IDO. These studies describe a bacterial molecule that modulates immune responses by inducing inhibitory DCs in a TLR4-dependent manner, and these cells have the capacity to inhibit T cell activation through IDO. We suggest that EPS or EPS-treated DCs can serve as novel agents for preventing aGvHD.

Antigen Uptake After Intradermal Microinjection Depends on Antigen Nature and Formulation, but Not on Injection Depth

The skin is an attractive alternative administration route for allergy vaccination, as the skin is rich in dendritic cells (DCs) and is easily accessible. In the skin multiple subsets of DCs with distinct roles reside at different depths. In this study antigen (=allergen for allergy) formulations were injected in ex vivo human skin in a depth-controlled manner by using a hollow microneedle injection system. Biopsies were harvested at the injection site, which were then cultured for 72 h. Subsequently, the crawled-out cells were collected from the medium and analyzed with flow cytometry. Intradermal administration of ovalbumin (OVA, model antigen) solution at various depths in the skin did not affect the migration and maturation of DCs. OVA was taken up efficiently by the DCs, and this was not affected by the injection depth. In contrast, Bet v 1, the major allergen in birch pollen allergy, was barely taken up by dermal DCs (dDCs). Antigens were more efficiently taken up by CD14⁺ dDCs than CD1a⁺ dDCs, which in turn were more efficient at taken up antigen than Langerhans cells. Subsequently, both OVA and Bet v 1 were formulated in cationic and anionic liposomes, which altered antigen uptake drastically following intradermal microinjection. While OVA uptake was reduced by formulation in liposomes, Bet v 1 uptake in dDCs was increased by encapsulation in both cationic and anionic liposomes. This highlights the potential use of liposomes as adjuvant in intradermal allergy vaccine delivery. In conclusion, we observed that antigen uptake after intradermal injection was not affected by injection depth, but varied between different antigens and formulation.

The synergistic strategies for the immuno-oncotherapy with photothermal nanoagents

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

Out of balance: the role of evolutionary mismatches in the sex disparity in autoimmune disease

Over the past century autoimmune disease incidence has increased rapidly in (post-) industrialised, affluent societies, suggesting that changes in ecology and lifestyle are driving this development. Epidemiological studies show that (i) 80% of autoimmune disease patients are female, (ii) autoimmune diseases co-occur more often in women, and (iii) the incidence of some autoimmune diseases is increasing faster in women than in men. The female preponderance in autoimmunity is most pronounced between puberty and menopause, suggesting that diverging sex hormone levels during the reproductive years are implicated in autoimmune disease development. Using an evolutionary perspective, we build on the hypotheses that female immunity is cyclical in menstruating species and that natural selection shaped the female immune system to optimise the implantation and gestation of a semi-allogeneic foetus. We propose that cyclical immunomodulation and female immune tolerance mechanisms are currently out of balance because of a mismatch between the conditions under which they evolved and (post-)industrialised, affluent lifestyles. We suggest that current changes in autoimmune disease prevalence may be caused by increases in lifetime exposure to cyclical immunomodulation and ovarian hormone exposure, reduced immune challenges, increased reproductive lifespan, changed reproductive patterns, and enhanced positive energy balance associated with (post-)industrialised, affluent lifestyles. We discuss proximate mechanisms by which oestrogen and progesterone influence tolerance induction and immunomodulation, and review the effect of the menstrual cycle, pregnancy, and contraceptive use on autoimmune disease incidence and symptoms.

The Flt3L/Flt3 Axis in Dendritic Cell Biology and Cancer Immunotherapy

Dendritic cells (DCs) prime anti-tumor T cell responses in tumor-draining lymph nodes and can restimulate T effector responses in the tumor site. Thus, in addition to unleashing T cell effector activity, current immunotherapies should be directed to boost DC function. Herein, we review the potential function of Flt3L as a tool for cancer immunotherapy. Flt3L is a growth factor that acts in Flt3-expressing multipotent progenitors and common lymphoid progenitors. Despite the broad expression of Flt3 in the hematopoietic progenitors, the main effect of the Flt3/Flt3L axis, revealed by the characterization of mice deficient in these genes, is the generation of conventional DCs (cDCs) and plasmacytoid DCs (pDCs). However, Flt3 signaling through PI3K and mTOR may also affect the function of mature DCs. We recapitulate the use of Flt3L in preclinical studies either as a single agent or in combination with other cancer therapies. We also analyze the use of Flt3L in clinical trials. The strong correlation between type 1 cDC (cDC1) infiltration of human cancers with overall survival in many cancer types suggests the potential use of Flt3L to boost expansion of this DC subset. However, this may need the combination of Flt3L with other immunomodulatory agents to boost cancer immunotherapy.

The Immune System in Transfusion-Related Acute Lung Injury Prevention and Therapy: Update and Perspective

As an initiator of respiratory distress, transfusion-related acute lung injury (TRALI) is regarded as one of the rare complications associated with transfusion medicine. However, to date, the pathogenesis of TRALI is still unclear, and specific therapies are unavailable. Understanding the mechanisms of TRALI may promote the design of preventive and therapeutic strategies. The immune system plays vital roles in reproduction, development and homeostasis. Sterile tissue damage, such as physical trauma, ischemia, or reperfusion injury, induces an inflammatory reaction that results in wound healing and regenerative mechanisms. In other words, in addition to protecting against pathogens, the immune response may be strongly associated with TRALI prevention and treatment through a variety of immunomodulatory strategies to inhibit excessive immune system activation. Immunotherapy based on immune cells or immunological targets may eradicate complications. For example, IL-10 therapy is a promising therapeutic strategy to explore further. This review will focus on ultramodern advances in our understanding of the potential role of the immune system in TRALI prevention and treatment.

Development of an Inflammatory CD14+ Dendritic Cell Subset in Humanized Mice

Humanized mouse models are attractive experimental models for analyzing the development and functions of human dendritic cells (DCs) in vivo. Although various types of DC subsets, including DC type 3 (DC3s), have been identified in humans, it remains unclear whether humanized mice can reproduce heterogeneous DC subsets. CD14, classically known as a monocyte/macrophage marker, is reported as an indicator of DC3s. We previously observed that some CD14⁺ myeloid cells expressed CD1c, a pan marker for bona fide conventional DC2 (cDC2s), in humanized mouse models in which human FLT3L and GM-CSF genes were transiently expressed using in vivo transfection (IVT). Here, we aimed to elucidate the identity of CD14⁺CD1c⁺ DC-like cells in humanized mouse models. We found that CD14⁺CD1c⁺ cells were phenotypically different from cDC2s; CD14⁺CD1c⁺ cells expressed CD163 but not CD5, whereas cDC2s expressed CD5 but not CD163. Furthermore, CD14⁺CD1c⁺ cells primed and polarized naïve CD4⁺ T cells toward IFN-γ⁺ Th1 cells more profoundly than cDC2s. Transcriptional analysis revealed that CD14⁺CD1c⁺ cells expressed several DC3-specific transcripts, such as CD163, S100A8, and S100A9, and were clearly segregated from cDC2s and monocytes. When lipopolysaccharide was administered to the humanized mice, the frequency of CD14⁺CD1c⁺ cells producing IL-6 and TNF-α was elevated, indicating a pro-inflammatory signature. Thus, humanized mice are able to sustain development of functional CD14⁺CD1c⁺ DCs, which are equivalent to DC3 subset observed in humans, and they could be useful for analyzing the development and function of DC3s in vivo.

Therapeutic Advances in Diabetes, Autoimmune, and Neurological Diseases

Since 2015, 170 small molecules, 60 antibody-based entities, 12 peptides, and 15 gene- or cell-therapies have been approved by FDA for diverse disease indications. Recent advancement in medicine is facilitated by identification of new targets and mechanisms of actions, advancement in discovery and development platforms, and the emergence of novel technologies. Early disease detection, precision intervention, and personalized treatments have revolutionized patient care in the last decade. In this review, we provide a comprehensive overview of current and emerging therapeutic modalities developed in the recent years. We focus on nine diseases in three major therapeutics areas, diabetes, autoimmune, and neurological disorders. The pathogenesis of each disease at physiological and molecular levels is discussed and recently approved drugs as well as drugs in the clinic are presented.

Zbtb10 transcription factor is crucial for murine cDC1 activation and cytokine secretion

Dendritic cell (DC) activation and cytokine production is tightly regulated. In this study, we found that Zbtb10 expression is activation dependent and it is essential for the immunogenic function of cDC1. Zbtb10 knockdown (KD) significantly reduced the expression of co-stimulatory genes CD80 and CD86 along with cytokines including IL-12, IL-6, and IL-10, in activated cDC1 Mutu-DC line. Consequently, the clonal expansion of CD44⁺ effector T cells in co-cultured CD4⁺ T cells was drastically reduced owing to significantly reduced IL-2. At the same time, these CD44⁺ effector T cells were unable to differentiate toward Tbet⁺ IFNγ⁺ Th1 subtype. Instead, an increased frequency of Th2 cells expressing GATA3⁺ and IL-13⁺ was observed. Interestingly, in Zbtb10 KD condition the co-cultured T cells depicted increased expression of PD1 and LAG3, the T-cell anergic markers. Moreover, the global transcriptome analysis identified that Zbtb10 is pertinent for DC activation and its depletion in cDC1 completely shuts down their immune responses. Mechanistic analysis revealed that Zbtb10 KD enhanced the expression of NKRF (NF-κB repressing factor) leading to drastic suppression of NF-κB related genes. Zbtb10 KD abrogated p65 and RelB nuclear translocation, thereby controlling the activation and maturation of cDC1 and the ensuing adaptive T cell responses.

Tolerogenic Immunotherapy: Targeting DC Surface Receptors to Induce Antigen-Specific Tolerance

Dendritic cells (DCs) are well-established as major players in the regulation of immune responses. They either induce inflammatory or tolerogenic responses, depending on the DC-subtype and stimuli they receive from the local environment. This dual capacity of DCs has raised therapeutic interest for their use to modify immune-activation via the generation of tolerogenic DCs (tolDCs). Several compounds such as vitamin D3, retinoic acid, dexamethasone, or IL-10 and TGF-β have shown potency in the induction of tolDCs. However, an increasing interest exists in defining tolerance inducing receptors on DCs for new targeting strategies aimed to develop tolerance inducing immunotherapies, on which we focus particular in this review. Ligation of specific cell surface molecules on DCs can result in antigen presentation to T cells in the presence of inhibitory costimulatory molecules and tolerogenic cytokines, giving rise to regulatory T cells. The combination of factors such as antigen structure and conformation, delivery method, and receptor specificity is of paramount importance. During the last decades, research provided many tools that can specifically target various receptors on DCs to induce a tolerogenic phenotype. Based on advances in the knowledge of pathogen recognition receptor expression profiles in human DC subsets, the most promising cell surface receptors that are currently being explored as possible targets for the induction of tolerance in DCs will be discussed. We also review the different strategies that are being tested to target DC receptors such as antigen-carbohydrate conjugates, antibody-antigen fusion proteins and antigen-adjuvant conjugates.

Tumor cells, rather than dendritic cells, deliver antigen to the lymph node for cross-presentation

It is widely accepted that generation of tumor specific CD8+ T-cell responses occur via cross-priming; however the source of tumor antigen for this event is unknown. We examined the source and form of tumor antigen required for cross-presentation in the local lymph node (LN) using a syngeneic mouse tumor model expressing a marker antigen. We found that cross-presentation of this model tumor antigen in the LN is dependent on continuous traffic of antigen from the tumor site, but without any detectable migration of tumor resident dendritic cells (DCs). Instead, small numbers of tumor cells metastasize to local LNs where they are exposed to a localized CTL attack, resulting in delivery of tumor antigen into the cross-presentation pathway.

Epigenetic Remodeling in Innate Immunity and Inflammation

The innate immune response is a rapid response to pathogens or danger signals. It is precisely activated not only to efficiently eliminate pathogens but also to avoid excessive inflammation and tissue damage. cis-Regulatory element-associated chromatin architecture shaped by epigenetic factors, which we define as the epiregulome, endows innate immune cells with specialized phenotypes and unique functions by establishing cell-specific gene expression patterns, and it also contributes to resolution of the inflammatory response. In this review, we focus on two aspects: (a) how niche signals during lineage commitment or following infection and pathogenic stress program epiregulomes by regulating gene expression levels, enzymatic activities, or gene-specific targeting of chromatin modifiers and (b) how the programed epiregulomes in turn mediate regulation of gene-specific expression, which contributes to controlling the development of innate cells, or the response to infection and inflammation, in a timely manner. We also discuss the effects of innate immunometabolic rewiring on epiregulomes and speculate on several future challenges to be encountered during the exploration of the master regulators of epiregulomes in innate immunity and inflammation.

Trial watch: Peptide vaccines in cancer therapy

Prophylactic vaccination constitutes one of the most prominent medical achievements of history. This concept was first demonstrated by the pioneer work of Edward Jenner, dating back to the late 1790s, after which an array of preparations that confer life-long protective immunity against several infectious agents has been developed. The ensuing implementation of nation-wide vaccination programs has de facto abated the incidence of dreadful diseases including rabies, typhoid, cholera and many others. Among all, the most impressive result of vaccination campaigns is surely represented by the eradication of natural smallpox infection, which was definitively certified by the WHO in 1980. The idea of employing vaccines as anticancer interventions was first theorized in the 1890s by Paul Ehrlich and William Coley. However, it soon became clear that while vaccination could be efficiently employed as a preventive measure against infectious agents, anticancer vaccines would have to (1) operate as therapeutic, rather than preventive, interventions (at least in the vast majority of settings), and (2) circumvent the fact that tumor cells often fail to elicit immune responses. During the past 30 y, along with the recognition that the immune system is not irresponsive to tumors (as it was initially thought) and that malignant cells express tumor-associated antigens whereby they can be discriminated from normal cells, considerable efforts have been dedicated to the development of anticancer vaccines. Some of these approaches, encompassing cell-based, DNA-based and purified component-based preparations, have already been shown to exert conspicuous anticancer effects in cohorts of patients affected by both hematological and solid malignancies. In this Trial Watch, we will summarize the results of recent clinical trials that have evaluated/are evaluating purified peptides or full-length proteins as therapeutic interventions against cancer.

Using gold nanoparticles for enhanced intradermal delivery of poorly soluble auto-antigenic peptides

Ultra-small 1-2 nm gold nanoparticles (NP) were conjugated with a poorly-soluble peptide auto-antigen, associated with type 1 diabetes, to modify the peptide pharmacokinetics, following its intradermal delivery. Peptide distribution was characterized, in vivo, after delivery using either conventional intradermal injection or a hollow microneedle device. The poorly-soluble peptide was effectively presented in distant lymph nodes (LN), spleen and draining LN when conjugated to the nanoparticles, whereas peptide alone was only presented in the draining LN. By contrast, nanoparticle conjugation to a highly-soluble peptide did not enhance in vivo distribution. Transfer of both free peptide and peptide-NPs from the skin to LN was reduced in mice lacking lymphoid homing receptor CCR7, suggesting that both are actively transported by migrating dendritic cells to LN. Collectively, these data demonstrate that intradermally administered ultra-small gold nanoparticles can widen the distribution of poorly-soluble auto-antigenic peptides to multiple lymphoid organs, thus enhancing their use as potential therapeutics.

Trial watch: Prognostic and predictive value of the immune infiltrate in cancer

Solid tumors are constituted of a variety of cellular components, including bona fide malignant cells as well as endothelial, structural and immune cells. On one hand, the tumor stroma exerts major pro-tumorigenic and immunosuppressive functions, reflecting the capacity of cancer cells to shape the microenvironment to satisfy their own metabolic and immunological needs. On the other hand, there is a component of tumor-infiltrating leucocytes (TILs) that has been specifically recruited in the attempt to control tumor growth. Along with the recognition of the critical role played by the immune system in oncogenesis, tumor progression and response to therapy, increasing attention has been attracted by the potential prognostic and/or predictive role of the immune infiltrate in this setting. Data from large clinical studies demonstrate indeed that a robust infiltration of neoplastic lesions by specific immune cell populations, including (but not limited to) CD8⁺ cytotoxic T lymphocytes, Th1 and Th17 CD4⁺ T cells, natural killer cells, dendritic cells, and M1 macrophages constitutes an independent prognostic indicator in several types of cancer. Conversely, high levels of intratumoral CD4⁺CD25⁺FOXP3⁺ regulatory T cells, Th2 CD4⁺ T cells, myeloid-derived suppressor cells, M2 macrophages and neutrophils have frequently been associated with dismal prognosis. So far, only a few studies have addressed the true predictive potential of TILs in cancer patients, generally comforting the notion that—at least in some clinical settings—the immune infiltrate can reliably predict if a specific patient will respond to therapy or not. In this Trial Watch, we will summarize the results of clinical trials that have evaluated/are evaluating the prognostic and predictive value of the immune infiltrate in the context of solid malignancies.