The Importance of Dendritic Cells in Maintaining Immune Tolerance

Unmasking the NLRP3 inflammasome in dendritic cells as a potential therapeutic target for autoimmunity, cancer, and infectious conditions

Proper and functional immune response requires a complex interaction between innate and adaptive immune cells, which dendritic cells (DCs) are the primary actors in this coordination as professional antigen-presenting cells. DCs are armed with numerous pattern recognition receptors (PRRs) such as nucleotide-binding and oligomerization domain-like receptors (NLRs) like NLRP3, which influence the development of their activation state upon sensation of ligands. NLRP3 is a crucial component of the immune system for protection against tumors and infectious agents, because its activation leads to the assembly of inflammasomes that cause the formation of active caspase-1 and stimulate the maturation and release of proinflammatory cytokines. But, when NLRP3 becomes overactivated, it plays a pathogenic role in the progression of several autoimmune disorders. So, NLRP3 activation is strictly regulated by diverse signaling pathways that are mentioned in detail in this review. Furthermore, the role of NLRP3 in all of the diverse immune cells' subsets is briefly mentioned in this study because NLRP3 plays a pivotal role in modulating other immune cells which are accompanied by DCs' responses and subsequently influence differentiation of T cells to diverse T helper subsets and even impact on cytotoxic CD8+ T cells' responses. This review sheds light on the functional and therapeutic role of NLRP3 in DCs and its contribution to the occurrence and progression of autoimmune disorders, prevention of diverse tumors' development, and recognition and annihilation of various infectious agents. Furthermore, we highlight NLRP3 targeting potential for improving DC-based immunotherapeutic approaches, to be used for the benefit of patients suffering from these disorders.

Delivering CRISPR to the HIV-1 reservoirs

Human immunodeficiency virus type 1 (HIV-1) infection is well known as one of the most complex and difficult viral infections to cure. The difficulty in developing curative strategies arises in large part from the development of latent viral reservoirs (LVRs) within anatomical and cellular compartments of a host. The clustered regularly interspaced short palindromic repeats/ CRISPR-associated protein 9 (CRISPR/Cas9) system shows remarkable potential for the inactivation and/or elimination of integrated proviral DNA within host cells, however, delivery of the CRISPR/Cas9 system to infected cells is still a challenge. In this review, the main factors impacting delivery, the challenges for delivery to each of the LVRs, and the current successes for delivery to each reservoir will be discussed.

Engineering antigen-presenting cells for immunotherapy of autoimmunity

Autoimmune diseases are burdensome conditions that affect a significant fraction of the global population. The hallmark of autoimmune disease is a host's immune system being licensed to attack its tissues based on specific antigens. There are no cures for autoimmune diseases. The current clinical standard for treating autoimmune diseases is the administration of immunosuppressants, which weaken the immune system and reduce auto-inflammatory responses. However, people living with autoimmune diseases are subject to toxicity, fail to mount a sufficient immune response to protect against pathogens, and are more likely to develop infections. Therefore, there is a concerted effort to develop more effective means of targeting immunomodulatory therapies to antigen-presenting cells, which are involved in modulating the immune responses to specific antigens. In this review, we highlight approaches that are currently in development to target antigen-presenting cells and improve therapeutic outcomes in autoimmune diseases.

Regulation of Tumor Dendritic Cells by Programmed Cell Death 1 Pathways

The advent of immune checkpoint blockade therapy has revolutionized cancer treatments and is partly responsible for the significant decline in cancer-related mortality observed during the last decade. Immune checkpoint inhibitors, such as anti-programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1), have demonstrated remarkable clinical successes in a subset of cancer patients. However, a considerable proportion of patients remain refractory to immune checkpoint blockade, prompting the exploration of mechanisms of treatment resistance. Whereas much emphasis has been placed on the role of PD-L1 and PD-1 in regulating the activity of tumor-infiltrating T cells, recent studies have now shown that this immunoregulatory axis also directly regulates myeloid cell activity in the tumor microenvironment including tumor-infiltrating dendritic cells. In this review, I discuss the most recent advances in the understanding of how PD-1, PD-L1, and programmed cell death ligand 2 regulate the function of tumor-infiltrating dendritic cells, emphasizing the need for further mechanistic studies that could facilitate the development of novel combination immunotherapies for improved cancer patient benefit.

Everolimus treatment enhances inhibitory immune checkpoint molecules' expression in monocyte-derived dendritic cells

BACKGROUND

Antigen-specific T-cell immunity is provided by dendritic cells (DCs), which are specialized antigen-presenting cells. Furthermore, they establish a link between innate and adaptive immune responses. Currently, DC modification is a new approach for the therapy of several disorders. During solid organ transplantation, Everolimus, which is a mammalian target of rapamycin (mTOR) inhibitor, was initially utilized to suppress the immune system's functionality. Due to the intervention of Everolimus in various signaling pathways in cells and its modulatory properties on the immune system, this study aims to investigate the effect of treatment with Everolimus on the maturation and expression of immune checkpoint genes in monocyte-derived DCs.

METHODS

To isolate monocytes from PBMCs, the CD14 marker was used via the MACS method. Monocytes were cultured and induced to differentiate into monocyte-derived DCs by utilizing GM-CSF and IL-4 cytokines. On the fifth day, immature DCs were treated with Everolimus and incubated for 24 h. On the sixth day, the flow cytometry technique was used to investigate the effect of Everolimus on the phenotypic characteristics of DCs. In the end, the expression of immune checkpoint genes in both the Everolimus-treated and untreated DCs groups was assessed using the real-time PCR method.

RESULTS

The findings of this research demonstrated that the administration of Everolimus to DCs led to a notable rise in human leukocyte antigen (HLA)-DR expression and a decrease in CD11c expression. Furthermore, there was a significant increase in the expression of immune checkpoint molecules, namely CTLA-4, VISTA, PD-L1, and BTLA, in DCs treated with Everolimus.

CONCLUSION

The findings of this study show that Everolimus can target DCs and affect their phenotype and function in order to shift them toward a partially tolerogenic state. However, additional research is required to gain a comprehensive understanding of the precise impact of Everolimus on the activation status of DCs.

Anti-intercellular adhesion molecule 1 monomaintenance therapy induced long-term liver allograft survival without chronic rejection

Calcineurin inhibitors (CNIs) are essential in liver transplantation (LT); however, their long-term use leads to various adverse effects. The anti-intercellular adhesion molecule (ICAM)-1 monoclonal antibody MD3 is a potential alternative to CNI. Despite its promising results with short-term therapy, overcoming the challenge of chronic rejection remains important. Thus, we aimed to investigate the outcomes of long-term MD3 therapy with monthly MD3 monomaintenance in nonhuman primate LT models. Rhesus macaques underwent major histocompatibility complex-mismatched allogeneic LT. The conventional immunosuppression group (Con-IS, n = 4) received steroid, tacrolimus, and sirolimus by 4 months posttransplantation. The induction MD3 group (IN-MD3, n = 5) received short-term MD3 therapy for 3 months with Con-IS. The maintenance MD3 group (MA-MD3, n = 4) received MD3 for 3 months, monthly doses by 2 years, and then quarterly. The MA-MD3 group exhibited stable liver function without overt infection and had significantly better liver allograft survival than the IN-MD3 group. Development of donor-specific antibody and chronic rejection were suppressed in the MA-MD3 group but not in the IN-MD3 group. Donor-specific T cell responses were attenuated in the MA-MD3 group. In conclusion, MD3 monomaintenance therapy without maintenance CNI provides long-term liver allograft survival by suppressing chronic rejection, offering a potential breakthrough for future human trials.

Adipose-derived stem cell modulate tolerogenic dendritic cell-induced T cell regulation is correlated with activation of Notch-NFκB signaling

BACKGROUND

Adipose-derived stem cells (ASCs) are recognized for their potential immunomodulatory properties. In the immune system, tolerogenic dendritic cells (DCs), characterized by an immature phenotype, play a crucial role in inducing regulatory T cells (Tregs) and promoting immune tolerance. Notch1 signaling has been identified as a key regulator in the development and function of DCs. However, the precise involvement of Notch1 pathway in ASC-mediated modulation of tolerogenic DCs and its impact on immune modulation remain to be fully elucidated. This study aims to investigate the interplay between ASCs and DCs, focusing the role of Notch1 signaling and downstream pathways in ASC-modulated tolerogenic DCs.

METHODS

Rat bone marrow-derived myeloid DCs were directly co-cultured with ASCs to generate ASC-treated DCs (ASC-DCs). Notch signaling was inhibited using DAPT, while NFκB pathways were inhibited by NEMO binding domain peptide and si-NIK. Flow cytometry assessed DC phenotypes. Real-time quantitative PCR, Western blotting and immunofluorescence determined the expression of Notch1, Jagged1 and the p52/RelB complex in ASC- DCs.

RESULTS

Notch1 and Jagged1 were highly expressed on both DCs and ASCs. ASC-DCs displayed significantly reduced levels of CD80, CD86 and MHC II compared to mature DCs. Inhibiting the Notch pathway with DAPT reversed the dedifferentiation effects. The percentage of induced CD25+/FOXP3+/CD4+ Tregs decreased when ASC-DCs were treated with DAPT (inhibition of the Notch pathway) and si-NIK (inhibition of the non-canonical NFκB pathway).

CONCLUSIONS

ASCs induce DC tolerogenicity by inhibiting maturation and promoting downstream Treg generation, involving the Notch and NFκB pathways. ASC-induced tolerogenic DCs can be a potential immunomodulatory tool for clinical application.

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

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

Migratory CD103+CD11b+ cDC2s in Peyer's patches are critical for gut IgA responses following oral immunization

Induction and regulation of specific intestinal immunoglobulin (Ig)A responses critically depend on dendritic cell (DC) subsets and the T cells they activate in the Peyer's patches (PP). We found that oral immunization with cholera toxin (CT) as an adjuvant resulted in migration-dependent changes in the composition and localization of PP DC subsets with increased numbers of cluster of differentiation (CD)103- conventional DC (cDC)2s and lysozyme-expressing DC (LysoDCs) in the subepithelial dome and of CD103+ cDC2s that expressed CD101 in the T cell zones, while oral ovalbumin (OVA) tolerization was instead associated with greater accumulation of cDC1s and peripherally induced regulatory T cells (pTregs) in this area. Decreased IgA responses were observed after CT-adjuvanted immunization in huCD207DTA mice lacking CD103+ cDC2s, while oral OVA tolerization was inefficient in cDC1-deficient Batf3-/- mice. Using OVA transgenic T cell receptor CD4 T cell adoptive transfer models, we found that co-transferred endogenous wildtype CD4 T cells can hinder the induction of OVA-specific IgA responses through secretion of interleukin-10. CT could overcome this blocking effect, apparently through a modulating effect on pTregs while promoting an expansion of follicular helper T cells. The data support a model where cDC1-induced pTreg normally suppresses PP responses for any given antigen and where CT's oral adjuvanticity effect is dependent on promoting follicular helper T cell responses through induction of CD103+ cDC2s.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

An engineered influenza virus to deliver antigens for lung cancer vaccination

The development of cancer neoantigen vaccines that prime the anti-tumor immune responses has been hindered in part by challenges in delivery of neoantigens to the tumor. Here, using the model antigen ovalbumin (OVA) in a melanoma model, we demonstrate a chimeric antigenic peptide influenza virus (CAP-Flu) system for delivery of antigenic peptides bound to influenza A virus (IAV) to the lung. We conjugated attenuated IAVs with the innate immunostimulatory agent CpG and, after intranasal administration to the mouse lung, observed increased immune cell infiltration to the tumor. OVA was then covalently displayed on IAV-CPG using click chemistry. Vaccination with this construct yielded robust antigen uptake by dendritic cells, a specific immune cell response and a significant increase in tumor-infiltrating lymphocytes compared to peptides alone. Lastly, we engineered the IAV to express anti-PD1-L1 nanobodies that further enhanced regression of lung metastases and prolonged mouse survival after rechallenge. Engineered IAVs can be equipped with any tumor neoantigen of interest to generate lung cancer vaccines.

Tolerogenic Nano-/Microparticle Vaccines for Immunotherapy

Autoimmune diseases, allergies, transplant rejections, generation of antidrug antibodies, and chronic inflammatory diseases have impacted a large group of people across the globe. Conventional treatments and therapies often use systemic or broad immunosuppression with serious efficacy and safety issues. Tolerogenic vaccines represent a concept that has been extended from their traditional immune-modulating function to induction of antigen-specific tolerance through the generation of regulatory T cells. Without impairing immune homeostasis, tolerogenic vaccines dampen inflammation and induce tolerogenic regulation. However, achieving the desired potency of tolerogenic vaccines as preventive and therapeutic modalities calls for precise manipulation of the immune microenvironment and control over the tolerogenic responses against the autoantigens, allergens, and/or alloantigens. Engineered nano-/microparticles possess desirable design features that can bolster targeted immune regulation and enhance the induction of antigen-specific tolerance. Thus, particle-based tolerogenic vaccines hold great promise in clinical translation for future treatment of aforementioned immune disorders. In this review, we highlight the main strategies to employ particles as exciting tolerogenic vaccines, with a focus on the particles' role in facilitating the induction of antigen-specific tolerance. We describe the particle design features that facilitate their usage and discuss the challenges and opportunities for designing next-generation particle-based tolerogenic vaccines with robust efficacy to promote antigen-specific tolerance for immunotherapy.

Antigen cross-presentation by dendritic cells: A critical axis in cancer immunotherapy

Dendritic cells (DCs) are professional antigen-presenting cells that play a key role in shaping adaptive immunity. DCs have a unique ability to sample their environment, capture and process exogenous antigens into peptides that are then loaded onto major histocompatibility complex class I molecules for presentation to CD8+ T cells. This process, called cross-presentation, is essential for initiating and regulating CD8+ T cell responses against tumors and intracellular pathogens. In this review, we will discuss the role of DCs in cancer immunity, the molecular mechanisms underlying antigen cross-presentation by DCs, the immunosuppressive factors that limit the efficiency of this process in cancer, and approaches to overcome DC dysfunction and therapeutically promote antitumoral immunity.

Transdermally delivered tolerogenic nanoparticles induced effective immune tolerance for asthma treatment

Induction of antigen-specific immune tolerance for the treatment of allergic or autoimmune diseases is an attractive strategy. Herein, we investigated the protective effect of a transdermal microneedle patch against allergic asthma by stimulating allergen-specific immune tolerance. We fabricated biodegradable tolerogenic nanoparticles (tNPs) that are loaded with a model allergen ovalbumin (OVA) and an immunomodulator rapamycin, and filled the tNPs into microneedle tips by centrifugation to form sustained-release microneedles. After intradermal immunization, the microneedles successfully delivered the cargos into the skin and sustainedly released them for over 96 h. Importantly, the microneedles induced allergen-specific regulatory T cells (Treg), decreased the levels of pro-inflammatory cytokines and antibodies while increased anti-inflammation cytokines, finally leading to restored immune homeostasis. The lung tissue analysis illustrated that the sustained-release microneedles significantly reduced the infiltration of eosinophils, decreased the accumulation of mucus and collagen, and significantly relived asthma symptoms. Our results suggested that the sustained-release microneedle-based transdermal delivery system can induce antigen-specific immune tolerance with improved compliance and efficacy, providing a new therapeutic strategy for the treatment of allergic and autoimmune diseases.

Glioma-Immune Cell Crosstalk in Tumor Progression

Glioma progression is a complex process controlled by molecular factors that coordinate the crosstalk between tumor cells and components of the tumor microenvironment (TME). Among these, immune cells play a critical role in cancer survival and progression. The complex interplay between cancer cells and the immune TME influences the outcome of immunotherapy and other anti-cancer therapies. Here, we present an updated view of the pro- and anti-tumor activities of the main myeloid and lymphocyte cell populations in the glioma TME. We review the underlying mechanisms involved in crosstalk between cancer cells and immune cells that enable gliomas to evade the immune system and co-opt these cells for tumor growth. Lastly, we discuss the current and experimental therapeutic options being developed to revert the immunosuppressive activity of the glioma TME. Knowledge of the complex interplay that elapses between tumor and immune cells may help develop new combination treatments able to overcome tumor immune evasion mechanisms and enhance response to immunotherapies.

Using the power of innate immunoprofiling to understand vaccine design, infection, and immunity

In the field of immunology, a systems biology approach is crucial to understanding the immune response to infection and vaccination considering the complex interplay between genetic, epigenetic, and environmental factors. Significant progress has been made in understanding the innate immune response, including cell players and critical signaling pathways, but many questions remain unanswered, including how the innate immune response dictates host/pathogen responses and responses to vaccines. To complicate things further, it is becoming increasingly clear that the innate immune response is not a linear pathway but is formed from complex networks and interactions. To further our understanding of the crosstalk and complexities, systems-level analyses and expanded experimental technologies are now needed. In this review, we discuss the most recent immunoprofiling techniques and discuss systems approaches to studying the global innate immune landscape which will inform on the development of personalized medicine and innovative vaccine strategies.

Lactobacillus johnsonii N6.2 phospholipids induce immature-like dendritic cells with a migratory-regulatory-like transcriptional signature

Shifts in the gut microbiota composition, called dysbiosis, have been directly associated with acute and chronic diseases. However, the underlying biological systems connecting gut dysbiosis to systemic inflammatory pathologies are not well understood. Phospholipids (PLs) act as precursors of both, bioactive inflammatory and resolving mediators. Their dysregulation is associated with chronic diseases including cancer. Gut microbial-derived lipids are structurally unique and capable of modulating host's immunity. Lactobacillus johnsonii N6.2 is a Gram-positive gut symbiont with probiotic characteristics. L. johnsonii N6.2 reduces the incidence of autoimmunity in animal models of Type 1 Diabetes and improves general wellness in healthy volunteers by promoting, in part, local and systemic anti-inflammatory responses. By utilizing bioassay-guided fractionation methods with bone marrow-derived dendritic cells (BMDCs), we report here that L. johnsonii N6.2 purified lipids induce a transcriptional signature that resembles that of migratory (mig) DCs. RNAseq-based analysis showed that BMDCs stimulated with L. johnsonii N6.2 total lipids upregulate maturation-mig related genes Cd86, Cd40, Ccr7, Icam1 along with immunoregulatory genes including Itgb8, Nfkbiz, Jag1, Adora2a, IL2ra, Arg1, and Cd274. Quantitative reverse transcription (qRT)-PCR analysis indicated that PLs are the bioactive lipids triggering the BMDCs response. Antibody-blocking of surface Toll-like receptor (TLR)2 resulted in boosted PL-mediated upregulation of pro-inflammatory Il6. Chemical inhibition of the IKKα kinase from the non-canonical NF-κB pathway specifically restricted upregulation of Il6 and Tnf. Phenotypically, PL-stimulated BMDCs displayed an immature like-phenotype with significantly increased surface ICAM-1. This study provides insight into the immunoregulatory capacity of Gram-positive, gut microbial-derived phospholipids on innate immune responses.

Cell and biomaterial delivery strategies to induce immune tolerance

The prevalence of immune-mediated disorders, including autoimmune conditions and allergies, is steadily increasing. However, current therapeutic approaches are often non-specific and do not address the underlying pathogenic condition, often resulting in impaired immunity and a state of generalized immunosuppression. The emergence of technologies capable of selectively inhibiting aberrant immune activation in a targeted, antigen (Ag)-specific manner by exploiting the body's intrinsic tolerance pathways, all without inducing adverse side effects, holds significant promise to enhance patient outcomes. In this review, we will describe the body's natural mechanisms of central and peripheral tolerance as well as innovative delivery strategies using cells and biomaterials targeting innate and adaptive immune cells to promote Ag-specific immune tolerance. Additionally, we will discuss the challenges and future opportunities that warrant consideration as we navigate the path toward clinical implementation of tolerogenic strategies to treat immune-mediated diseases.

Myeloid-derived suppressor cells and tolerogenic dendritic cells are distinctively induced by PI3K and Wnt signaling pathways

Imbalanced immune responses are a prominent hallmark of cancer and autoimmunity. Myeloid cells can be overly suppressive, inhibiting protective immune responses or inactive not controlling autoreactive immune cells. Understanding the mechanisms that induce suppressive myeloid cells, such as myeloid-derived suppressor cells (MDSCs) and tolerogenic dendritic cells (TolDCs), can facilitate the development of immune-restoring therapeutic approaches. MDSCs are a major barrier for effective cancer immunotherapy by suppressing antitumor immune responses in cancer patients. TolDCs are administered to patients to promote immune tolerance with the intent to control autoimmune disease. Here, we investigated the development and suppressive/tolerogenic activity of human MDSCs and TolDCs to gain insight into signaling pathways that drive immunosuppression in these different myeloid subsets. Moreover, monocyte-derived MDSCs (M-MDSCs) generated in vitro were compared to M-MDSCs isolated from head-and-neck squamous cell carcinoma patients. PI3K-AKT signaling was identified as being crucial for the induction of human M-MDSCs. PI3K inhibition prevented the downregulation of HLA-DR and the upregulation of reactive oxygen species and MerTK. In addition, we show that the suppressive activity of dexamethasone-induced TolDCs is induced by β-catenin-dependent Wnt signaling. The identification of PI3K-AKT and Wnt signal transduction pathways as respective inducers of the immunomodulatory capacity of M-MDSCs and TolDCs provides opportunities to overcome suppressive myeloid cells in cancer patients and optimize therapeutic application of TolDCs. Lastly, the observed similarities between generated- and patient-derived M-MDSCs support the use of in vitro-generated M-MDSCs as powerful model to investigate the functionality of human MDSCs.

OMIP-095: 40-Color spectral flow cytometry delineates all major leukocyte populations in murine lymphoid tissues

High-dimensional immunoprofiling is essential for studying host response to immunotherapy, infection, and disease in murine model systems. However, the difficulty of multiparameter panel design combined with a lack of existing murine tools has prevented the comprehensive study of all major leukocyte phenotypes in a single assay. Herein, we present a 40-color flow cytometry panel for deep immunophenotyping of murine lymphoid tissues, including the spleen, blood, Peyer's patches, inguinal lymph nodes, bone marrow, and thymus. This panel uses a robust set of surface markers capable of differentiating leukocyte subsets without the use of intracellular staining, thus allowing for the use of cells in downstream functional experiments or multiomic analyses. Our panel classifies T cells, B cells, natural killer cells, innate lymphoid cells, monocytes, macrophages, dendritic cells, basophils, neutrophils, eosinophils, progenitors, and their functional subsets by using a series of co-stimulatory, checkpoint, activation, migration, and maturation markers. This tool has a multitude of systems immunology applications ranging from serial monitoring of circulating blood signatures to complex endpoint analysis, especially in pre-clinical settings where treatments can modulate leukocyte abundance and/or function. Ultimately, this 40-color panel resolves a diverse array of immune cells on the axes of time, tissue, and treatment, filling the niche for a modern tool dedicated to murine immunophenotyping.

Early innate cell interactions with Mycobacterium tuberculosis in protection and pathology of tuberculosis

Tuberculosis (TB) remains a significant global health challenge, claiming the lives of up to 1.5 million individuals annually. TB is caused by the human pathogen Mycobacterium tuberculosis (Mtb), which primarily infects innate immune cells in the lungs. These immune cells play a critical role in the host defense against Mtb infection, influencing the inflammatory environment in the lungs, and facilitating the development of adaptive immunity. However, Mtb exploits and manipulates innate immune cells, using them as favorable niche for replication. Unfortunately, our understanding of the early interactions between Mtb and innate effector cells remains limited. This review underscores the interactions between Mtb and various innate immune cells, such as macrophages, dendritic cells, granulocytes, NK cells, innate lymphocytes-iNKT and ILCs. In addition, the contribution of alveolar epithelial cell and endothelial cells that constitutes the mucosal barrier in TB immunity will be discussed. Gaining insights into the early cellular basis of immune reactions to Mtb infection is crucial for our understanding of Mtb resistance and disease tolerance mechanisms. We argue that a better understanding of the early host-pathogen interactions could inform on future vaccination approaches and devise intervention strategies.

Oral mucosa immunity: ultimate strategy to stop spreading of pandemic viruses

Global pandemics are most likely initiated via zoonotic transmission to humans in which respiratory viruses infect airways with relevance to mucosal systems. Out of the known pandemics, five were initiated by respiratory viruses including current ongoing coronavirus disease 2019 (COVID-19). Striking progress in vaccine development and therapeutics has helped ameliorate the mortality and morbidity by infectious agents. Yet, organism replication and virus spread through mucosal tissues cannot be directly controlled by parenteral vaccines. A novel mitigation strategy is needed to elicit robust mucosal protection and broadly neutralizing activities to hamper virus entry mechanisms and inhibit transmission. This review focuses on the oral mucosa, which is a critical site of viral transmission and promising target to elicit sterile immunity. In addition to reviewing historic pandemics initiated by the zoonotic respiratory RNA viruses and the oral mucosal tissues, we discuss unique features of the oral immune responses. We address barriers and new prospects related to developing novel therapeutics to elicit protective immunity at the mucosal level to ultimately control transmission.

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

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

Identification of osteoarthritis-characteristic genes and immunological micro-environment features through bioinformatics and machine learning-based approaches

BACKGROUND

Osteoarthritis (OA) is a multifaceted chronic joint disease characterized by complex mechanisms. It has a detrimental impact on the quality of life for individuals in the middle-aged and elderly population while also imposing a significant socioeconomic burden. At present, there remains a lack of comprehensive understanding regarding the pathophysiology of OA. The objective of this study was to examine the genes, functional pathways, and immune infiltration characteristics associated with the development and advancement of OA.

METHODS

The Gene Expression Omnibus (GEO) database was utilized to acquire gene expression profiles. The R software was employed to conduct the screening of differentially expressed genes (DEGs) and perform enrichment analysis on these genes. The OA-characteristic genes were identified using the Weighted Gene Co-expression Network Analysis (WGCNA) and the Lasso algorithm. In addition, the infiltration levels of immune cells in cartilage were assessed using single-sample gene set enrichment analysis (ssGSEA). Subsequently, a correlation analysis was conducted to examine the relationship between immune cells and the OA-characteristic genes.

RESULTS

A total of 80 DEGs were identified. As determined by functional enrichment, these DEGs were associated with chondrocyte metabolism, apoptosis, and inflammation. Three OA-characteristic genes were identified using WGCNA and the lasso algorithm, and their expression levels were then validated using the verification set. Finally, the analysis of immune cell infiltration revealed that T cells and B cells were primarily associated with OA. In addition, Tspan2, HtrA1 demonstrated a correlation with some of the infiltrating immune cells.

CONCLUSIONS

The findings of an extensive bioinformatics analysis revealed that OA is correlated with a variety of distinct genes, functional pathways, and processes involving immune cell infiltration. The present study has successfully identified characteristic genes and functional pathways that hold potential as biomarkers for guiding drug treatment and facilitating molecular-level research on OA.

Dendritic cells resist to disulfiram-induced cytotoxicity, but reduced interleukin-12/23(p40) production

Disulfiram (DSF), a medication for alcoholism, has recently been used as a repurposing drug owing to its anticancer effects. Despite the crucial role of dendritic cells (DCs) in immune homeostasis and cancer therapy, the effects of DSF on the survival and function of DCs have not yet been studied. Therefore, we treated bone marrow-derived DCs with DSF and lipopolysaccharide (LPS) and performed various analyses. DCs are resistant to DSF and less cytotoxic than bone marrow cells and spleen cells. The viability and metabolic activity of DCs hardly decreased after treatment with DSF in the absence or presence of LPS. DSF did not alter the expression of surface markers (MHC II, CD86, CD40, and CD54), antigen uptake capability, or the antigen-presenting ability of LPS-treated DCs. DSF decreased the production of interleukin (IL)-12/23 (p40), but not IL-6 or tumor necrosis factor-α, in LPS-treated DCs. We considered the granulocyte-macrophage colony-stimulating factor (GM-CSF) as a factor to make DCs resistant to DSF-induced cytotoxicity. The resistance of DCs to DSF decreased when GM-CSF was not given or its signaling was inhibited. Also, GM-CSF upregulated the expression of a transcription factor XBP-1 which is essential for DCs' survival. This study demonstrated for the first time that DSF did not alter the function of DCs, had low cytotoxicity, and induced differential cytokine production.

BamQuery: a proteogenomic tool to explore the immunopeptidome and prioritize actionable tumor antigens

MHC-I-associated peptides deriving from non-coding genomic regions and mutations can generate tumor-specific antigens, including neoantigens. Quantifying tumor-specific antigens' RNA expression in malignant and benign tissues is critical for discriminating actionable targets. We present BamQuery, a tool attributing an exhaustive RNA expression to MHC-I-associated peptides of any origin from bulk and single-cell RNA-sequencing data. We show that many cryptic and mutated tumor-specific antigens can derive from multiple discrete genomic regions, abundantly expressed in normal tissues. BamQuery can also be used to predict MHC-I-associated peptides immunogenicity and identify actionable tumor-specific antigens de novo.

Transcriptional regulation of dendritic cell development and function

Dendritic cells (DCs) are sentinel immune cells that form a critical bridge linking the innate and adaptive immune systems. Extensive research addressing the cellular origin and heterogeneity of the DC network has revealed the essential role played by the spatiotemporal activity of key transcription factors. In response to environmental signals DC mature but it is only following the sensing of environmental signals that DC can induce an antigen specific T cell response. Thus, whilst the coordinate action of transcription factors governs DC differentiation, sensing of environmental signals by DC is instrumental in shaping their functional properties. In this review, we provide an overview that focuses on recent advances in understanding the transcriptional networks that regulate the development of the reported DC subsets, shedding light on the function of different DC subsets. Specifically, we discuss the emerging knowledge on the heterogeneity of cDC2s, the ontogeny of pDCs, and the newly described DC subset, DC3. Additionally, we examine critical transcription factors such as IRF8, PU.1, and E2-2 and their regulatory mechanisms and downstream targets. We highlight the complex interplay between these transcription factors, which shape the DC transcriptome and influence their function in response to environmental stimuli. The information presented in this review provides essential insights into the regulation of DC development and function, which might have implications for developing novel therapeutic strategies for immune-related diseases.

Unlocking the power of NOX2: A comprehensive review on its role in immune regulation

Reactive oxygen species (ROS) are a family of highly reactive molecules with numerous, often pleiotropic functions within the cell and the organism. Due to their potential to destroy biological structures such as membranes, enzymes and organelles, ROS have long been recognized as harmful yet unavoidable by-products of cellular metabolism leading to "oxidative stress" unless counterbalanced by cellular anti-oxidative defense mechanisms. Phagocytes utilize this destructive potential of ROS released in high amounts to defend against invading pathogens. In contrast, a regulated and fine-tuned release of "signaling ROS" (sROS) provides essential intracellular second messengers to modulate central aspects of immunity, including antigen presentation, activation of antigen presenting cells (APC) as well as the APC:T cell interaction during T cell activation. This regulated release of sROS is foremost attributed to the specialized enzyme NADPH-oxidase (NOX) 2 expressed mainly in myeloid cells such as neutrophils, macrophages and dendritic cells (DC). NOX-2-derived sROS are primarily involved in immune regulation and mediate protection against autoimmunity as well as maintenance of self-tolerance. Consequently, deficiencies in NOX2 not only result in primary immune-deficiencies such as Chronic Granulomatous Disease (CGD) but also lead to auto-inflammatory diseases and autoimmunity. A comprehensive understanding of NOX2 activation and regulation will be key for successful pharmaceutical interventions of such ROS-related diseases in the future. In this review, we summarize recent progress regarding immune regulation by NOX2-derived ROS and the consequences of its deregulation on the development of immune disorders.

UV radiation and air pollution as drivers of major autoimmune conditions

Autoimmune diseases comprise a very heterogeneous group of disorders characterized by disruptive immune responses against self-antigens, chronic morbidity and increased mortality. The incidence and prevalence of major autoimmune conditions are particularly high in the western world, at northern latitudes, and in industrialized countries. This study will mainly focus on five major autoimmune conditions, namely type 1 diabetes, multiple sclerosis, inflammatory bowel diseases, rheumatoid arthritis, and autoimmune thyroid disorders. Epidemiological and experimental evidence suggests a protective role of sunlight exposure on the etiology of major autoimmune conditions mediated by the endogenous production of vitamin D and nitric oxide. A historical perspective shows how the rise of anthropogenic air pollutants is temporally associated with dramatic increases in incidence of these conditions. The scattering caused by ambient particulate matter and the presence of tropospheric ozone can reduce the endogenous production of vitamin D and nitric oxide, which are implicated in maintaining the immune homeostasis. Air pollutants have direct detrimental effects on the human body and are deemed responsible of an increasingly higher portion of the annual burden of human morbidity and mortality. Air pollution contributes in systemic inflammation, activates oxidative pathways, induces epigenetic alterations, and modulates the function and phenotype of dendritic cells, Tregs, and T-cells. In this review, we provide epidemiological and mechanistic insights regarding the role of UV-mediated effects in immunity and how anthropic-derived air pollution may affect major autoimmune conditions through direct and indirect mechanisms.

Pathogenesis of Extraarticular Manifestations in Rheumatoid Arthritis-A Comprehensive Review

Rheumatoid arthritis (RA) is among the most prevalent and debilitating autoimmune inflammatory chronic diseases. Although it is primarily characterized by destructive peripheral arthritis, it is a systemic disease, and RA-related extraarticular manifestations (EAMs) can affect almost every organ, exhibit a multitude of clinical presentations, and can even be asymptomatic. Importantly, EAMs largely contribute to the quality of life and mortality of RA patients, particularly substantially increased risk of cardiovascular disease (CVD) which is the leading cause of death in RA patients. In spite of known risk factors related to EAM development, a more in-depth understanding of its pathophysiology is lacking. Improved knowledge of EAMs and their comparison to the pathogenesis of arthritis in RA could lead to a better understanding of RA inflammation overall and its initial phases. Taking into account that RA is a disorder that has many faces and that each person experiences it and responds to treatments differently, gaining a better understanding of the connections between the joint and extra-joint manifestations could help to create new treatments and improve the overall approach to the patient.

Association between CD34+ and CD3+ T-cells in allogeneic grafts and acute graft-versus-host disease in children undergoing allogeneic hematopoietic stem cell transplantation: A single-center study

BACKGROUND

Acute graft-versus-host disease (aGVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). We examined the association between the composition of the cell subsets present in allogeneic grafts (allografts) and the occurrence and severity of aGVHD in pediatric patients.

METHODS

We retrospectively analyzed 80 consecutive pediatric patients undergoing allo-HSCT at our center.

RESULTS

Both univariate and multivariate analyses showed that the number of CD34⁺ and CD3⁺ T-cells in allografts were the two highest risk factors associated with II-IV aGVHD. Using receiver operating characteristic analysis, the cutoff levels of the allo-HSCT cell doses were used to divide the recipients into low-dose and high-dose groups. The 100-day cumulative incidence of II-IV aGVHD in the high-dose CD34⁺ and CD3⁺ T-cells group was significantly higher than that of the low-dose group (CD34⁺: 57% vs. 29%, p = 0.009; CD3⁺: 63% vs. 18%, p < 0.001). No other clinical factors or cell subsets correlated with aGVHD incidence.

CONCLUSIONS

Our analysis indicates that the CD34⁺ and CD3⁺ T-cell numbers in the allografts could be the risk factors for the development of severe aGVHD (level II-IV). Further studies should aim to optimize the critical number of CD34⁺ and CD3⁺ T-cells to reduce the risk of severe aGVHD occurrence in pediatric patients.

Isolated Peptide from Spider Venom Modulates Dendritic Cells In Vitro: A Possible Application in Oncoimmunotherapy for Glioblastoma

Dendritic cells (DCs) vaccine is a potential tool for oncoimmunotherapy. However, it is known that this therapeutic strategy has failed in solid tumors, making the development of immunoadjuvants highly relevant. Recently, we demonstrated that Phoneutria nigriventer spider venom (PnV) components are cytotoxic to glioblastoma (GB) and activate macrophages for an antitumor profile. However, the effects of these molecules on the adaptive immune response have not yet been evaluated. This work aimed to test PnV and its purified fractions in DCs in vitro. For this purpose, bone marrow precursors were collected from male C57BL6 mice, differentiated into DCs and treated with venom or PnV-isolated fractions (F1—molecules < 3 kDa, F2—3 to 10 kDa and F3—>10 kDa), with or without costimulation with human GB lysate. The results showed that mainly F1 was able to activate DCs, increasing the activation-dependent surface marker (CD86) and cytokine release (IL-1β, TNF-α), in addition to inducing a typical morphology of mature DCs. From the F1 purification, a molecule named LW9 was the most effective, and mass spectrometry showed it to be a peptide. The present findings suggest that this molecule could be an immunoadjuvant with possible application in DC vaccines for the treatment of GB.

A multiscale mechanistic model of human dendritic cells for in-silico investigation of immune responses and novel therapeutics discovery

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) with the unique ability to mediate inflammatory responses of the immune system. Given the critical role of DCs in shaping immunity, they present an attractive avenue as a therapeutic target to program the immune system and reverse immune disease disorders. To ensure appropriate immune response, DCs utilize intricate and complex molecular and cellular interactions that converge into a seamless phenotype. Computational models open novel frontiers in research by integrating large-scale interaction to interrogate the influence of complex biological behavior across scales. The ability to model large biological networks will likely pave the way to understanding any complex system in more approachable ways. We developed a logical and predictive model of DC function that integrates the heterogeneity of DCs population, APC function, and cell-cell interaction, spanning molecular to population levels. Our logical model consists of 281 components that connect environmental stimuli with various layers of the cell compartments, including the plasma membrane, cytoplasm, and nucleus to represent the dynamic processes within and outside the DC, such as signaling pathways and cell-cell interactions. We also provided three sample use cases to apply the model in the context of studying cell dynamics and disease environments. First, we characterized the DC response to Sars-CoV-2 and influenza co-infection by in-silico experiments and analyzed the activity level of 107 molecules that play a role in this co-infection. The second example presents simulations to predict the crosstalk between DCs and T cells in a cancer microenvironment. Finally, for the third example, we used the Kyoto Encyclopedia of Genes and Genomes enrichment analysis against the model's components to identify 45 diseases and 24 molecular pathways that the DC model can address. This study presents a resource to decode the complex dynamics underlying DC-derived APC communication and provides a platform for researchers to perform in-silico experiments on human DC for vaccine design, drug discovery, and immunotherapies.

A root cause analysis to identify the mechanistic drivers of immunogenicity against the anti-VEGF biotherapeutic brolucizumab

Immunogenicity against intravitreally administered brolucizumab has been previously described and associated with cases of severe intraocular inflammation, including retinal vasculitis/retinal vascular occlusion (RV/RO). The presence of antidrug antibodies (ADAs) in these patients led to the initial hypothesis that immune complexes could be key mediators. Although the formation of ADAs and immune complexes may be a prerequisite, other factors likely contribute to some patients having RV/RO, whereas the vast majority do not. To identify and characterize the mechanistic drivers underlying the immunogenicity of brolucizumab and the consequence of subsequent ADA-induced immune complex formation, a translational approach was performed to bridge physicochemical characterization, structural modeling, sequence analysis, immunological assays, and a quantitative systems pharmacology model that mimics physiological conditions within the eye. This approach revealed that multiple factors contributed to the increased immunogenic potential of brolucizumab, including a linear epitope shared with bacteria, non-natural surfaces due to the single-chain variable fragment format, and non-native drug species that may form over prolonged time in the eye. Consideration of intraocular drug pharmacology and disease state in a quantitative systems pharmacology model suggested that immune complexes could form at immunologically relevant concentrations modulated by dose intensity. Assays using circulating immune cells from treated patients or treatment-naïve healthy volunteers revealed the capacity of immune complexes to trigger cellular responses such as enhanced antigen presentation, platelet aggregation, endothelial cell activation, and cytokine release. Together, these studies informed a mechanistic understanding of the clinically observed immunogenicity of brolucizumab and associated cases of RV/RO.

Estrogen Receptor Signaling in the Immune System

The immune system functions in a sexually dimorphic manner, with females exhibiting more robust immune responses than males. However, how female sex hormones affect immune function in normal homeostasis and in autoimmunity is poorly understood. In this review, we discuss how estrogens affect innate and adaptive immune cell activity and how dysregulation of estrogen signaling underlies the pathobiology of some autoimmune diseases and cancers. The potential roles of the major circulating estrogens, and each of the 3 estrogen receptors (ERα, ERβ, and G-protein coupled receptor) in the regulation of the activity of different immune cells are considered. This provides the framework for a discussion of the impact of ER modulators (aromatase inhibitors, selective estrogen receptor modulators, and selective estrogen receptor downregulators) on immunity. Synthesis of this information is timely given the considerable interest of late in defining the mechanistic basis of sex-biased responses/outcomes in patients with different cancers treated with immune checkpoint blockade. It will also be instructive with respect to the further development of ER modulators that modulate immunity in a therapeutically useful manner.

Adjuvant effect of dendritic cells activator Imiquimod in genetic immunization with HIV-1 p55 Gag

Dendritic cells (DC) are important antigen-presenting cells that have abilities to induce and maintain T-cell immunity, or attenuate it during hyperimmunization. Additional activation of DCs may be useful for vaccination purposes. Imiquimod is known to be a specific agonist of the Toll-like receptors (TLR7), which are located mainly on DCs. To study the effect of DC stimulation on the effectiveness of an HIV-1 p55 gag DNA vaccine in a mice model, we employed 25, 50, and 100 nM of Imiquimod as an adjuvant. Subsequently, Western blot analysis was used to quantify p55 protein production after the immunization. To characterize T-cells immune response, both the frequency of IFN-γ -secreting cells and IFN-γ and IL-4 production were measured, via an ELIspot assay and ELISA, respectively. Low concentrations of Imiquimod were found to effectively stimulate Gag production and the magnitude of the T-cell immune response, whereas higher concentrations reduced vaccination effects. Our results show that the adjuvant effects of Imiquimod depend on concentration. The use of Imiquimod may be helpful to study DC to T cell communication, including possible induction of immunotolerance.

Insights into the immunomodulatory regulation of matrix metalloproteinase at the maternal-fetal interface during early pregnancy and pregnancy-related diseases

Trophoblast immune cell interactions are central events in the immune microenvironment at the maternal-fetal interface. Their abnormalities are potential causes of various pregnancy complications, including pre-eclampsia and recurrent spontaneous abortion. Matrix metalloproteinase (MMP) is highly homologous, zinc(II)-containing metalloproteinase involved in altered uterine hemodynamics, closely associated with uterine vascular remodeling. However, the interactions between MMP and the immune microenvironment remain unclear. Here we discuss the key roles and potential interplay of MMP with the immune microenvironment in the embryo implantation process and pregnancy-related diseases, which may contribute to understanding the establishment and maintenance of normal pregnancy and providing new therapeutic strategies. Recent studies have shown that several tissue inhibitors of metalloproteinases (TIMPs) effectively prevent invasive vascular disease by modulating the activity of MMP. We summarize the main findings of these studies and suggest the possibility of TIMPs as emerging biomarkers and potential therapeutic targets for a range of complications induced by abnormalities in the immune microenvironment at the maternal-fetal interface. MMP and TIMPs are promising targets for developing new immunotherapies to treat pregnancy-related diseases caused by immune imbalance.

Endotoxin-Tolerance Mimicking to Study TLR in Promotion of Tolerogenic DCs and Tr1 Cells

Dendritic cells (DCs) are key regulators of immunogenic and tolerogenic immune responses. Both these immune responses require DCs respectively to activate effector T cells or to induce their anergy and T regulatory activity. Modifications of DCs in the laboratory and several pharmacological agents can enhance and stabilize their tolerogenic properties. Recent evidences demonstrate that activation of specific toll-like receptors (TLRs) can be involved in induction of DCs with tolerogenic properties able to initiate T regulatory cell responses.In the present chapter, we show a detail protocol to obtain in vitro regulatory conventional DCs (cDCs) in response to repeated exposure to lipopolysaccharide (LPS), a ligand of TLR4, by mimicking the mechanism of endotoxin tolerance. Subsequently, the protective effect of cDCs' conditionate with LPS will be describe in in vivo inflammatory model of endotoxemia. Finally, we illustrate the method to study the ability of LPS-conditionate cDCs to promote T regulatory cells in ex vivo system.

Indirubin regulates T cell differentiation by promoting αVβ8 expression in bone marrow-derived dendritic cells to alleviate inflammatory bowel disease

Inflammatory bowel disease is a disease that can invade the whole digestive tract and is accompanied by immune abnormalities. Immune dysfunction involving dendritic cells (DCs) and T cells is recognized as a key factor in diseases. Indirubin (IDRB) exerts antiinflammatory effects and can help in treating immune diseases. This study aimed to isolate bone marrow-derived dendritic cells (BMDCs) using lipopolysaccharide (LPS) to obtain mature DCs (mDCs). The expression of CD80, CD86, CD40, and MHC-II was detected using flow cytometry after treatment with IDRB. αVβ8 siRNA was used to knock down αVβ8 in mDCs, and the expression of CD80, CD86, CD40, and MHC-II was detected. Meanwhile, DCs were co-cultured with T cells. Then, T cell differentiation was detected using flow cytometry, and the cytokine levels were detected using enzyme-linked immunosorbent assay. The animal model of dextran sulfate sodium (DSS)-induced inflammatory bowel disease was established in mice. After intervention with IDRB and αVβ8 shRNA, the intestinal tissues were evaluated using H&E staining, disease activity index (DAI) score, and histological damage index, and the corresponding factors and cytokines to regulatory T cells (Treg) and Th17 were measured. The results showed that αVβ8 was expressed in immature DCs and mDCs. CD80, CD86, CD40, and MHC-II expression decreased after IDRB treatment in mDCs. Meanwhile, the expression of TNF-α and TGF-β also decreased after IDRB treatment. The effect of IDRB on the expression of CD80, CD86, CD40, MHC-II, TNF-α, and TGF-β in mDCs was reversed by αVβ8 siRNA. The Treg differentiation increased after IDRB treatment, while the differentiation of Th17 cells was inhibited. This effect of IDRB was reversed by mDCs after treatment with αVβ8 siRNA. In vivo experiments showed that IDRB alleviated the symptoms of inflammatory bowel disease in animals. Enteritis significantly reduced, and the effect of IDRB was reversed by αVβ8 shRNA. The results suggested that IDRB regulated the differentiation of T cells by mediating the maturation of BMDCs through αVβ8. This study confirmed the therapeutic effect of IDRB in inflammatory bowel disease and suggested that IDRB might serve as a potential drug.

Inhibition of PI3K/C/EBPβ axis in tolerogenic bone marrow-derived dendritic cells of NOD mice promotes Th17 differentiation and diabetes development

Dendritic cells (DCs) are key regulators of the adaptive immune response. Tolerogenic dendritic cells play a crucial role in inducing and maintaining immune tolerance in autoimmune diseases such as type 1 diabetes in humans as well as in the NOD mouse model. We previously reported that bone marrow-derived DCs (BM.DCs) from NOD mice, generated with a low dose of GM-CSF (GM/DCs), induce Treg differentiation and are able to protect NOD mice from diabetes. We had also found that the p38 MAPK/C/EBPβ axis is involved in regulating the phenotype, as well as the production of IL-10 and IL-12p70, by tolerogenic GM/DCs. Here, we report that the inhibition of the PI3K signaling switched the cytokine profile of GM/DCs toward Th17-promoting cytokines without affecting their phenotype. PI3K inhibition abrogated the production of IL-10 by GM/DCs, whereas it enhanced their production of IL-23 and TGFβ. Inhibition of PI3K signaling in tolerogenic GM/DCs also induced naive CD4⁺ T cells differentiation toward Th17 cells. Mechanistically, PI3K inhibition increased the DNA-binding activity of C/EBPβ through a GSK3-dependent pathway, which is important to maintain the semimature phenotype of tolerogenic GM/DCs. Furthermore, analysis of C/EBPβ^-/- GM/DCs demonstrated that C/EBPβ is required for IL-23 production. Of physiological relevance, the level of protection from diabetes following transfusion of GM/DCs into young NOD mice was significantly reduced when NOD mice were transfused with GM/DCs pretreated with a PI3K inhibitor. Our data suggest that PI3K/C/EBPβ signaling is important in controlling tolerogenic function of GM/DCs by limiting their Th17-promoting cytokines.

Curative islet and hematopoietic cell transplantation in diabetic mice without toxic bone marrow conditioning

Mixed hematopoietic chimerism can promote immune tolerance of donor-matched transplanted tissues, like pancreatic islets. However, adoption of this strategy is limited by the toxicity of standard treatments that enable donor hematopoietic cell engraftment. Here, we address these concerns with a non-myeloablative conditioning regimen that enables hematopoietic chimerism and allograft tolerance across fully mismatched major histocompatibility complex (MHC) barriers. Treatment with an αCD117 antibody, targeting c-Kit, administered with T cell-depleting antibodies and low-dose radiation permits durable multi-lineage chimerism in immunocompetent mice following hematopoietic cell transplant. In diabetic mice, co-transplantation of donor-matched islets and hematopoietic cells durably corrects diabetes without chronic immunosuppression and no appreciable evidence of graft-versus-host disease (GVHD). Donor-derived thymic antigen-presenting cells and host-derived peripheral regulatory T cells are likely mediators of allotolerance. These findings provide the foundation for safer bone marrow conditioning and cell transplantation regimens to establish hematopoietic chimerism and islet allograft tolerance.

Research Advances in the Treatment of Allergic Rhinitis by Probiotics

Allergic rhinitis (AR) impairs the quality of life of patients and reduces the efficiency of social work, it is an increasingly serious public medical and economic problem in the world. Conventional anti-allergic drugs for the treatment of allergic rhinitis (AR) can cause certain side effects, which limit the quality of life of patients. Therefore, it makes sense to look for other forms of treatment. Several studies in recent years have shown that probiotics have shown anti-allergic effects in various mouse and human studies. For example, the application of certain probiotic strains can effectively relieve the typical nasal and ocular symptoms of allergic rhinitis in children and adults, thereby improving the quality of life and work efficiency. At the same time, previous studies in humans and mice have found that probiotics can produce multiple effects, such as reduction of Th2 cell inflammatory factors and/or increase of Th1 cell inflammatory factors, changes in allergy-related immunoglobulins and cell migration, regulate Th1/Th2 balance or restore intestinal microbiota disturbance. For patients with limited activity or allergic rhinitis with more attacks and longer attack duration, oral probiotics have positive effects. The efficacy of probiotics in the prevention and treatment of allergic rhinitis is remarkable, but its specific mechanism needs further study. This review summarizes the research progress of probiotics in the treatment of allergic rhinitis in recent years.

Immune-metabolic interactions in homeostasis and the progression to NASH

The incidence of non-alcoholic fatty liver disease (NAFLD) has increased significantly over the past two decades. NAFLD ranges from simple steatosis (NAFL) to nonalcoholic steatohepatitis (NASH) and predisposes to fibrosis and hepatocellular carcinoma (HCC). The importance of the immune system in hepatic physiology and in the progression of NAFLD is increasingly recognized. At homeostasis, the liver participates in immune defense against pathogens and in tolerance of gut-derived microbial compounds. Hepatic immune cells also respond to metabolic stimuli and have a role in NAFLD progression to NASH. In this review, we discuss how metabolic perturbations affect immune cell phenotype and function in NAFL and NASH, and then focus on the role of immune cells in liver homeostasis and in the development of NASH.

Pathogenesis from Inflammation to Cancer in NASH-Derived HCC

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and one of the deadliest cancers worldwide. As opposed to the majority of patients with HCC, approximately 20–30% of cases of non-alcoholic steatohepatitis (NASH)-derived HCC develop malignant tumours in the absence of liver cirrhosis. NASH is characterized by metabolic dysregulation, chronic inflammation and cell death in the liver, which provide a favorable setting for the transformation of inflammation into cancer. This review aims to describe the pathogenesis and the underlying mechanism of the transition from inflammation to cancer in NASH.

Molecular subtype identification and predictive power of N6-methyladenosine regulator in unexplained recurrent pregnancy loss

The etiology of recurrent pregnancy loss (RPL) is complicated and effective clinical preventive measures are lacking. Identifying biomarkers for RPL has been challenging, and to date, little is known about the role of N6-methyladenosine (m6A) regulators in RPL. Expression data for m6A regulators in 29 patients with RPL and 29 healthy controls were downloaded from the Gene Expression Omnibus (GEO) database. To establish a diagnostic model for unexplained RPL, differential gene expression analysis was conducting for 36 m6A regulators using least absolute shrinkage and selection operator (LASSO) regression. Unsupervised cluster analysis was conducted on hub genes, and probable mechanisms were explored using gene set enrichment analysis (GSEA) and gene ontology (GO) analysis. Correlations between m6A-related differentially expressed genes and immune infiltration were analyzed using single-sample GSEA. A total of 18 m6A regulators showed significant differences in expression in RPL: 10 were upregulated and eight were downregulated. Fifteen m6A regulators were integrated and used to construct a diagnostic model for RPL that had good predictive efficiency and robustness in differentiating RPL from control samples, with an overall area under the curve (AUC) value of 0.994. Crosstalk was identified between 10 hub genes, miRNAs, and transcription factors (TFs). For example, YTHDF2 was targeted by mir-1-3p and interacted with embryonic development-related TFs such as FOXA1 and GATA2. YTHDF2 was also positively correlated with METTL14 (r = 0.5983, p < 0.001). Two RPL subtypes (Cluster-1 and Cluster-2) with distinct hub gene signatures were identified. GSEA and GO analysis revealed that the differentially expressed genes were mainly associated with immune processes and cell cycle signaling pathway (normalized enrichment score, NES = -1.626, p < 0.001). Immune infiltration was significantly higher in Cluster-1 than in Cluster-2 (p < 0.01). In conclusion, we demonstrated that m6A modification plays a critical role in RPL. We also developed and validated a diagnostic model for RPL prediction based on m6A regulators. Finally, we identified two distinct RPL subtypes with different biological processes and immune statuses.

Volatile organic compounds: A proinflammatory activator in autoimmune diseases

The etiopathogenesis of inflammatory and autoimmune diseases, including pulmonary disease, atherosclerosis, and rheumatoid arthritis, has been linked to human exposure to volatile organic compounds (VOC) present in the environment. Chronic inflammation due to immune breakdown and malfunctioning of the immune system has been projected to play a major role in the initiation and progression of autoimmune disorders. Macrophages, major phagocytes involved in the regulation of chronic inflammation, are a major target of VOC. Excessive and prolonged activation of immune cells (T and B lymphocytes) and overexpression of the master pro-inflammatory constituents [cytokine and tumor necrosis factor-alpha, together with other mediators (interleukin-6, interleukin-1, and interferon-gamma)] have been shown to play a central role in the pathogenesis of autoimmune inflammatory responses. The function and efficiency of the immune system resulting in immunostimulation and immunosuppression are a result of exogenous and endogenous factors. An autoimmune disorder is a by-product of the overproduction of these inflammatory mediators. Additionally, an excess of these toxicants helps in promoting autoimmunity through alterations in DNA methylation in CD4 T cells. The purpose of this review is to shed light on the possible role of VOC exposure in the onset and progression of autoimmune diseases.

Deinococcus radiodurans R1 Lysate Induces Tolerogenic Maturation in Lipopolysaccharide-Stimulated Dendritic Cells and Protects Dextran Sulfate Sodium-Induced Colitis in Mice

Deinococcus radiodurans is an extremophilic bacterium that can thrive in harsh environments. This property can be attributed to its unique metabolites that possess strong antioxidants and other pharmacological properties. To determine the potential of D. radiodurans R1 lysate (DeinoLys) as a pharmacological candidate for inflammatory bowel disease (IBD), we investigated the anti-inflammatory activity of DeinoLys in bone marrow-derived dendritic cells (BMDCs) and a colitis mice model. Lipopolysaccharide (LPS)-stimulated BMDCs treated with DeinoLys exhibited alterations in their phenotypic and functional properties by changing into tolerogenic DCs, including strongly inhibited proinflammatory cytokines (TNF-α and IL-12p70) and surface molecule expression and activated DC-induced T cell proliferation/activation with high IL-10 production. These phenotypic and functional changes in BMDCs induced by DeinoLys in the presence of LPS were abrogated by IL-10 neutralization. Furthermore, oral administration of DeinoLys significantly reduced clinical symptoms against dextran sulfate sodium-induced colitis, including body weight loss, disease activity index, histological severity in colon tissue, and lower myeloperoxidase level in mice. Our results establish DeinoLys as a potential anti-inflammatory candidate for IBD therapy.

Local delivery of low-dose anti–CTLA-4 to the melanoma lymphatic basin leads to systemic T reg reduction and effector T cell activation

Preclinical studies show that locoregional CTLA-4 blockade is equally effective in inducing tumor eradication as systemic delivery, without the added risk of immune-related side effects. This efficacy is related to access of the CTLA-4 blocking antibodies to tumor-draining lymph nodes (TDLNs). Local delivery of anti–CTLA-4 after surgical removal of primary melanoma, before sentinel lymph node biopsy (SLNB), provides a unique setting to clinically assess the role of TDLN in the biological efficacy of locoregional CTLA-4 blockade. Here, we have evaluated the safety, tolerability, and immunomodulatory effects in the SLN and peripheral blood of a single dose of tremelimumab [a fully human immunoglobulin gamma-2 (IgG2) mAb directed against CTLA-4] in a dose range of 2 to 20 mg, injected intradermally at the tumor excision site 1 week before SLNB in 13 patients with early-stage melanoma (phase 1 trial; NCT04274816). Intradermal delivery was safe and well tolerated and induced activation of migratory dendritic cell (DC) subsets in the SLN. It also induced profound and durable decreases in regulatory T cell (T reg ) frequencies and activation of effector T cells in both SLN and peripheral blood. Moreover, systemic T cell responses against NY-ESO-1 or MART-1 were primed or boosted ( N = 7), in association with T cell activation and central memory T cell differentiation. These findings indicate that local administration of anti–CTLA-4 may offer a safe and promising adjuvant treatment strategy for patients with early-stage melanoma. Moreover, our data demonstrate a central role for TDLN in the biological efficacy of CTLA-4 blockade and support TDLN-targeted delivery methods.

Thymus Functionality Needs More Than a Few TECs

The thymus, a primary lymphoid organ, produces the T cells of the immune system. Originating from the 3^rd pharyngeal pouch during embryogenesis, this organ functions throughout life. Yet, thymopoiesis can be transiently or permanently damaged contingent on the types of systemic stresses encountered. The thymus also undergoes a functional decline during aging, resulting in a progressive reduction in naïve T cell output. This atrophy is evidenced by a deteriorating thymic microenvironment, including, but not limited, epithelial-to-mesenchymal transitions, fibrosis and adipogenesis. An exploration of cellular changes in the thymus at various stages of life, including mouse models of in-born errors of immunity and with single cell RNA sequencing, is revealing an expanding number of distinct cell types influencing thymus functions. The thymus microenvironment, established through interactions between immature and mature thymocytes with thymus epithelial cells (TEC), is well known. Less well appreciated are the contributions of neural crest cell-derived mesenchymal cells, endothelial cells, diverse hematopoietic cell populations, adipocytes, and fibroblasts in the thymic microenvironment. In the current review, we will explore the contributions of the many stromal cell types participating in the formation, expansion, and contraction of the thymus under normal and pathophysiological processes. Such information will better inform approaches for restoring thymus functionality, including thymus organoid technologies, beneficial when an individuals’ own tissue is congenitally, clinically, or accidentally rendered non-functional.

Characterization of 7-Methylguanosine Identified Biochemical Recurrence and Tumor Immune Microenvironment in Prostate Cancer

Prostate cancer (PCa) has a high incidence rate, mortality rate, and biochemical recurrence (BCR) rate. 7-Methylguanosine (m7G), as one of the RNA modifications, has been considered to be actively involved in cancer-related translation disorders in recent years. Therefore, we first used The Cancer Genome Atlas (TCGA) database to identify prognosis and m7G-related long non-coding RNAs (lncRNAs). Then we randomly divided the samples into the training set and test set and then constructed and verified the m7G lnRNA prognostic model (m7Gscore) by the least absolute shrinkage and selection operator (LASSO) regression analysis. The m7Gscore has been proved to be an independent marker of BCR-free survival in patients with PCa. Furthermore, the m7Gscore was significantly correlated with the tumor immune microenvironment (TIME) and somatic mutation of PCa patients and had the potential to be an indicator for the selection of drug treatment. We also clustered TCGA cohort into three m7G-related patterns (C1, C2, and C3). The Kaplan-Meier survival analysis revealed that C1 had the best BCR-free survival and C3 had the worst. The TIME was also significantly distinct among the three m7G-related patterns. According to the TIME characteristics of the patterns, we defined C1, C2, and C3 as immune-desert phenotype, immune-inflamed phenotype, and immune-excluded phenotype, respectively.