OX40 signaling favors the induction of T(H)9 cells and airway inflammation

MicroRNA-19b exacerbates systemic sclerosis through promoting Th9 cells

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by fibrosis of the skin and multiple vital organs, but the immunological pathogenesis of SSc remains unclear. We show here that miR-19b promotes Th9 cells that exacerbate SSc. Specifically, miR-19b and interleukin (IL)-9 increase in CD4+ T cells in experimental SSc in mice induced with bleomycin. Inhibiting miR-19b reduces Th9 cells and ameliorates the disease. Mechanistically, transforming growth factor beta (TGF-β) plus IL-4 activates pSmad3-Ser213 and TRAF6-K63 ubiquitination by suppressing NLRC3. Activated TRAF6 sequentially promotes TGF-β-activated kinase 1 (TAK1) and nuclear factor κB (NF-κB) p65 phosphorylation, leading to the upregulation of miR-19b. Notably, miR-19b activated Il9 gene expression by directly suppressing atypical E2F family member E2f8. In patients with SSc, higher levels of IL9 and MIR-19B correlate with worse disease progression. Our findings reveal miR-19b as a key factor in Th9 cell-mediated SSc pathogenesis and should have clinical implications for patients with SSc.

TL1A priming induces a multi-cytokine Th9 cell phenotype that promotes robust allergic inflammation in murine models of asthma

Multi-cytokine-producing Th9 cells secrete IL-9 and type 2 cytokines and mediate mouse and human allergic inflammation. However, the cytokines that promote a multi-cytokine secreting phenotype have not been defined. Tumor necrosis factor superfamily member TL1A signals through its receptor DR3 to increase IL-9. Here we demonstrate that TL1A increases expression of IL-9 and IL-13 co-expressing cells in murine Th9 cell cultures, inducing a multi-cytokine phenotype. Mechanistically, this is linked to histone modifications allowing for increased accessibility at the Il9 and Il13 loci. We further show that TL1A alters the transcription factor network underlying expression of IL-9 and IL-13 in Th9 cells and increases binding of transcription factors to Il9 and Il13 loci. TL1A-priming enhances the pathogenicity of Th9 cells in murine models of allergic airway disease through the increased expression of IL-9 and IL-13. Lastly, in both chronic and memory-recall models of allergic airway disease, blockade of TL1A signaling decreases the multi-cytokine Th9 cell population and attenuates the allergic phenotype. Taken together, these data demonstrate that TL1A promotes the development of multi-cytokine Th9 cells that drive allergic airway diseases and that targeting pathogenic T helper cell-promoting cytokines could be an effective approach for modifying disease.

Altered cancer metabolism and implications for next-generation CAR T-cell therapies

This review critically examines the evolving landscape of chimeric antigen receptor (CAR) T-cell therapy in treating solid tumors, with a particular focus on the metabolic challenges within the tumor microenvironment. CAR T-cell therapy has demonstrated remarkable success in hematologic malignancies, yet its efficacy in solid tumors remains limited. A significant barrier is the hostile milieu of the tumor microenvironment, which impairs CAR T-cell survival and function. This review delves into the metabolic adaptations of cancer cells and their impact on immune cells, highlighting the competition for nutrients and the accumulation of immunosuppressive metabolites. It also explores emerging strategies to enhance CAR T-cell metabolic fitness and persistence, including genetic engineering and metabolic reprogramming. An integrated approach, combining metabolic interventions with CAR T-cell therapy, has the potential to overcome these constraints and improve therapeutic outcomes in solid tumors.

TL1A is an epithelial alarmin that cooperates with IL-33 for initiation of allergic airway inflammation

Epithelium-derived cytokines or alarmins, such as interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP), are major players in type 2 immunity and asthma. Here, we demonstrate that TNF-like ligand 1A (TL1A) is an epithelial alarmin, constitutively expressed in alveolar epithelium at steady state in both mice and humans, which cooperates with IL-33 for early induction of IL-9high ILC2s during the initiation of allergic airway inflammation. Upon synergistic activation by IL-33 and TL1A, lung ILC2s acquire a transient IL-9highGATA3low "ILC9" phenotype and produce prodigious amounts of IL-9. A combination of large-scale proteomic analyses, lung intravital microscopy, and adoptive transfer of ILC9 cells revealed that high IL-9 expression distinguishes a multicytokine-producing state-of-activated ILC2s with an increased capacity to initiate IL-5-dependent allergic airway inflammation. Similar to IL-33 and TSLP, TL1A is expressed in airway basal cells in healthy and asthmatic human lungs. Together, these results indicate that TL1A is an epithelium-derived cytokine and an important cofactor of IL-33 in the airways.

Locus of (IL-9) control: IL9 epigenetic regulation in cellular function and human disease

Interleukin-9 (IL-9) is a multifunctional cytokine with roles in a broad cross-section of human diseases. Like many cytokines, IL-9 is transcriptionally regulated by a group of noncoding regulatory elements (REs) surrounding the IL9 gene. These REs modulate IL-9 transcription by forming 3D loops that recruit transcriptional machinery. IL-9-promoting transcription factors (TFs) can bind REs to increase locus accessibility and permit chromatin looping, or they can be recruited to already accessible chromatin to promote transcription. Ample mechanistic and genome-wide association studies implicate this interplay between IL-9-modulating TFs and IL9 cis-REs in human physiology, homeostasis, and disease.

Combination of percutaneous thermal ablation and adoptive Th9 cell transfer therapy against non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is one of the predominant malignancies globally. Percutaneous thermal ablation (PTA) has gained widespread use among NSCLC patients, with the potential to elicit immune responses but limited therapeutic efficacies for advanced-stage disease. T-helper type 9 (Th9) cells are a subset of CD4+ effector T cells with robust and persistent anti-tumor effects. This study proposes to develop PTA-Th9 cell integrated therapy as a potential strategy for NSCLC treatment.

METHODS

The therapeutic efficacies were measured in mice models with subcutaneously transplanted, recurrence, or lung metastatic tumors. The tumor microenvironments (TMEs) were evaluated by flow cytometry. The cytokine levels were assessed by ELISA. The signaling molecules were determined by quantitative PCR and Western blotting. The translational potential was tested in the humanized NSCLC patient-derived xenograft (PDX) model.

RESULTS

We find that PTA combined with adoptive Th9 cell transfer therapy substantially suppresses tumor growth, recurrence, and lung metastasis, ultimately extending the survival of mice with NSCLC grafts, outperforming both PTA and Th9 cell transfer monotherapy. Analysis of TMEs indicates that combinatorial therapy significantly augments tumor-infiltrating Th9 cells, boosts anti-tumor effects of CD8+ T cells, and remodels tumor immunosuppressive microenvironments. Moreover, combinatorial therapy significantly strengthens the regional and circulation immune response of CD8+ T cells in mice with tumor lung metastasis and induces peripheral CD8+ T effector memory cells in mice with tumor recurrence. Mechanically, PTA reinforces the anti-tumor ability of Th9 cells primarily through upregulating interleukin (IL)-1β and subsequently activating the downstream STAT1/IRF1 pathway, which could be effectively blocked by intercepting IL-1β signaling. Finally, the enhanced therapeutic effect of combinatorial therapy is validated in humanized NSCLC PDX models.

CONCLUSIONS

Collectively, this study demonstrates that combinatorial therapy displays robust and durable anti-tumor efficacy and excellent translational potential, offering excellent prospects for translation and emerging as a promising approach for NSCLC treatment.

Communication between Mast Cells and Group 2 Innate Lymphoid Cells in the Skin

The skin is a dynamic organ with a complex immune network critical for maintaining balance and defending against various pathogens. Different types of cells in the skin, such as mast cells (MCs) and group 2 innate lymphoid cells (ILC2s), contribute to immune regulation and play essential roles in the early immune response to various triggers, including allergens. It is beneficial to dissect cell-to-cell interactions in the skin to elucidate the mechanisms underlying skin immunity. The current manuscript concentrates explicitly on the communication pathways between MCs and ILC2s in the skin, highlighting their ability to regulate immune responses, inflammation, and tissue repair. Furthermore, it discusses how the interactions between MCs and ILC2s play a crucial role in various skin conditions, such as autoimmune diseases, dermatological disorders, and allergic reactions. Understanding the complex interactions between MCs and ILC2s in different skin conditions is crucial to developing targeted treatments for related disorders. The discovery of shared pathways could pave the way for novel therapeutic interventions to restore immunological balance in diseased skin tissues.

Regulatory role of T helper 9/interleukin-9: Transplantation view

T helper 9 (Th9) cells, a subset of CD4+ T helper cells, have emerged as a valuable target for immune cell therapy due to their potential to induce immunomodulation and tolerance. The Th9 cells mainly produce interleukin (IL)-9 and are known for their defensive effects against helminth infections, allergic and autoimmune responses, and tumor suppression. This paper explores the mechanisms involved in the generation and differentiation of Th9 cells, including the cytokines responsible for their polarization and stabilization, the transcription factors necessary for their differentiation, as well as the role of Th9 cells in inflammatory and autoimmune diseases, allergic reactions, and cancer immunotherapies. Recent research has shown that the differentiation of Th9 cells is coregulated by the transcription factors transforming growth factor β (TGF-β), IL-4, and PU.1, which are also known to secrete IL-10 and IL-21. Multiple cell types, such as T and B cells, mast cells, and airway epithelial cells, are influenced by IL-9 due to its pleiotropic effects.

The NF-κB signaling system in the immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is an idiopathic, chronic condition characterized by episodes of inflammation in the gastrointestinal tract. The nuclear factor κB (NF-κB) system describes a family of dimeric transcription factors. Canonical NF-κB signaling is stimulated by and enhances inflammation, whereas noncanonical NF-κB signaling contributes to immune organogenesis. Dysregulation of NF-κB factors drives various inflammatory pathologies, including IBD. Signals from many immune sensors activate NF-κB subunits in the intestine, which maintain an equilibrium between local microbiota and host responses. Genetic association studies of patients with IBD and preclinical mouse models confirm the importance of the NF-κB system in host defense in the gut. Other studies have investigated the roles of these factors in intestinal barrier function and in inflammatory gut pathologies associated with IBD. NF-κB signaling modulates innate and adaptive immune responses and the production of immunoregulatory proteins, anti-inflammatory cytokines, antimicrobial peptides, and other tolerogenic factors in the intestine. Furthermore, genetic studies have revealed critical cell type-specific roles for NF-κB proteins in intestinal immune homeostasis, inflammation, and restitution that contribute to the etiopathology of IBD-associated manifestations. Here, we summarize our knowledge of the roles of these NF-κB pathways, which are activated in different intestinal cell types by specific ligands, and their cross-talk, in fueling aberrant intestinal inflammation. We argue that an in-depth understanding of aberrant immune signaling mechanisms may hold the key to identifying predictive or prognostic biomarkers and developing better therapeutics against inflammatory gut pathologies.

The OX40-TRAF6 axis promotes CTLA-4 degradation to augment antitumor CD8+ T-cell immunity

Immune checkpoint blockade (ICB), including anti-cytotoxic T-lymphocyte associated protein 4 (CTLA-4), benefits only a limited number of patients with cancer. Understanding the in-depth regulatory mechanism of CTLA-4 protein stability and its functional significance may help identify ICB resistance mechanisms and assist in the development of novel immunotherapeutic modalities to improve ICB efficacy. Here, we identified that TNF receptor-associated factor 6 (TRAF6) mediates Lys63-linked ubiquitination and subsequent lysosomal degradation of CTLA-4. Moreover, by using TRAF6-deficient mice and retroviral overexpression experiments, we demonstrated that TRAF6 promotes CTLA-4 degradation in a T-cell-intrinsic manner, which is dependent on the RING domain of TRAF6. This intrinsic regulatory mechanism contributes to CD8+ T-cell-mediated antitumor immunity in vivo. Additionally, by using an OX40 agonist, we demonstrated that the OX40-TRAF6 axis is responsible for CTLA-4 degradation, thereby controlling antitumor immunity in both tumor-bearing mice and patients with cancer. Overall, our findings demonstrate that the OX40-TRAF6 axis promotes CTLA-4 degradation and is a potential therapeutic target for the improvement of T-cell-based immunotherapies.

Transcription Factor Id1 Plays an Essential Role in Th9 Cell Differentiation by Inhibiting Tcf3 and Tcf4

T helper type 9 (Th9) cells play important roles in immune responses by producing interleukin-9 (IL-9). Several transcription factors are responsible for Th9 cell differentiation; however, transcriptional regulation of Th9 cells is not fully understood. Here, it is shown that Id1 is an essential transcriptional regulator of Th9 cell differentiation. Id1 is induced by IL-4 and TGF-β. Id1-deficient naïve CD4 T cells fail to differentiate into Th9 cells, and overexpression of Id1 induce expression of IL-9. Mass spectrometry analysis reveals that Id1 interacts with Tcf3 and Tcf4 in Th9 cells. In addition, RNA-sequencing, chromatin immunoprecipitation, and transient reporter assay reveal that Tcf3 and Tcf4 bind to the promoter region of the Il9 gene to suppress its expression, and that Id1 inhibits their function, leading to Th9 differentiation. Finally, Id1-deficient Th9 cells ameliorate airway inflammation in an animal model of asthma. Thus, Id1 is a transcription factor that plays an essential role in Th9 cell differentiation by inhibiting Tcf3 and Tcf4.

Nomenclature of allergic diseases and hypersensitivity reactions: Adapted to modern needs: An EAACI position paper

The exponential growth of precision diagnostic tools, including omic technologies, molecular diagnostics, sophisticated genetic and epigenetic editing, imaging and nano-technologies and patient access to extensive health care, has resulted in vast amounts of unbiased data enabling in-depth disease characterization. New disease endotypes have been identified for various allergic diseases and triggered the gradual transition from a disease description focused on symptoms to identifying biomarkers and intricate pathogenetic and metabolic pathways. Consequently, the current disease taxonomy has to be revised for better categorization. This European Academy of Allergy and Clinical Immunology Position Paper responds to this challenge and provides a modern nomenclature for allergic diseases, which respects the earlier classifications back to the early 20th century. Hypersensitivity reactions originally described by Gell and Coombs have been extended into nine different types comprising antibody- (I-III), cell-mediated (IVa-c), tissue-driven mechanisms (V-VI) and direct response to chemicals (VII). Types I-III are linked to classical and newly described clinical conditions. Type IVa-c are specified and detailed according to the current understanding of T1, T2 and T3 responses. Types V-VI involve epithelial barrier defects and metabolic-induced immune dysregulation, while direct cellular and inflammatory responses to chemicals are covered in type VII. It is notable that several combinations of mixed types may appear in the clinical setting. The clinical relevance of the current approach for allergy practice will be conferred in another article that will follow this year, aiming at showing the relevance in clinical practice where various endotypes can overlap and evolve over the lifetime.

STING-driven activation of T cells: relevance for the adoptive cell therapy of cancer

Adoptive cell therapy (ACT) can successfully treat hematopoietic cancers but lacks efficacy against solid tumors. This is due to insufficient T cell infiltration, high tumor heterogeneity, frequent antigen loss with subsequent tumor escape, and the immunosuppressive tumor microenvironment (TME). Alternative methods to boost the anticancer efficacy of adoptively transferred cells are actively pursued. Among adjuvants that are utilized to stimulate anticancer immune responses, ligands of the stimulator of interferon genes (STING) pathway have received increasing attention. STING activation can trigger dendritic cell (DC) activation and endogenous immune responses, thereby preventing tumor escape. Activation of the STING pathway in the context of ACT was accordingly associated with improved T cell trafficking and persistence in the TME combined with the reduced presence of immunosuppressive cells. Recent findings also suggest cell-intrinsic effects of STING ligands on T cells. Activation of the STING signaling pathway was in this regard shown to enhance effector functions of CD4+ and CD8+ T cells, suggesting that the STING signaling could be exploited to harness T cell anticancer functions. In this review, we will discuss how the STING signaling can be used to enhance the anticancer efficacy of ACT.

Challenges and opportunities in the development of combination immunotherapy with OX40 agonists

INTRODUCTION

Costimulatory members of the tumor necrosis factor receptor family, such as OX40 (CD134), provide essential survival and differentiation signals that enhance T cell function. Specifically, OX40 (CD134) agonists stimulate potent anti-tumor immunity in a variety of preclinical models but their therapeutic impact in patients with advanced malignancies has been limited thus far.

AREAS COVERED

In this review, we discuss the current state of combination immunotherapy with OX40 agonists including preclinical studies and recent clinical trials. We also discuss the strengths and limitations of these approaches and provide insight into alternatives that may help enhance the efficacy of combination OX40 agonist immunotherapy.

EXPERT OPINION

OX40 agonist immunotherapy has not yet demonstrated significant clinical activity as a monotherapy or in combination with immune checkpoint blockade (ICB), likely due to several factors including the timing of administration, drug potency, and selection of agents for combination therapy clinical trials. We believe that careful consideration of the biological mechanisms regulating OX40 expression and function may help inform new approaches, particularly in combination with novel agents, capable of increasing the therapeutic efficacy of this approach.

The World according to IL-9

Among the cytokines regulating immune cells, IL-9 has gained considerable attention for its ability to act on multiple cell types as a regulator of beneficial and pathologic immune responses. Yet, it is still not clearly defined how IL-9 impacts immune responses. IL-9 demonstrates a remarkable degree of tissue-specific functionality and has cellular sources that vary by tissue site and the context of the inflammatory milieu. Here, we provide perspective to summarize the biological activities of IL-9 and highlight cell type-specific roles in the immune pathogenesis of diseases. This perspective will be important in defining the diseases where targeting IL-9 as a therapeutic strategy would be beneficial and where it has the potential to complicate clinical outcomes.

Dynamic chromatin accessibility licenses STAT5- and STAT6-dependent innate-like function of TH9 cells to promote allergic inflammation

Allergic diseases are a major global health issue. Interleukin (IL)-9-producing helper T (TH9) cells promote allergic inflammation, yet TH9 cell effector functions are incompletely understood because their lineage instability makes them challenging to study. Here we found that resting TH9 cells produced IL-9 independently of T cell receptor (TCR) restimulation, due to STAT5- and STAT6-dependent bystander activation. This mechanism was seen in circulating cells from allergic patients and was restricted to recently activated cells. STAT5-dependent Il9/IL9 regulatory elements underwent remodeling over time, inactivating the locus. A broader 'allergic TH9' transcriptomic and epigenomic program was also unstable. In vivo, TH9 cells induced airway inflammation via TCR-independent, STAT-dependent mechanisms. In allergic patients, TH9 cell expansion was associated with responsiveness to JAK inhibitors. These findings suggest that TH9 cell instability is a negative checkpoint on bystander activation that breaks down in allergy and that JAK inhibitors should be considered for allergic patients with TH9 cell expansion.

Metabolic challenges and interventions in CAR T cell therapy

Chimeric antigen receptor (CAR) T cells have achieved true clinical success in treating hematological malignancy patients, laying the foundation of CAR T cells as a new pillar of cancer therapy. Although these promising effects have generated strong interest in expanding the treatment of CAR T cells to solid tumors, reproducible demonstration of clinical efficacy in the setting of solid tumors has remained challenging to date. Here, we review how metabolic stress and signaling in the tumor microenvironment, including intrinsic determinants of response to CAR T cell therapy and extrinsic obstacles, restrict the efficacy of CAR T cell therapy in cancer treatment. In addition, we discuss the use of novel approaches to target and rewire metabolic programming for CAR T cell manufacturing. Last, we summarize strategies that aim to improve the metabolic adaptability of CAR T cells to enhance their potency in mounting antitumor responses and survival within the tumor microenvironment.

The Emerging Role of IL-9 in the Anticancer Effects of Anti-PD-1 Therapy

PD-1 blockade rescues failing anticancer immune responses, resulting in durable remissions in some cancer patients. Cytokines such as IFNγ and IL-2 contribute to the anti-tumor effect of PD-1 blockade. IL-9 was identified over the last decade as a cytokine demonstrating a potent ability to harness the anticancer functions of innate and adaptive immune cells in mice. Recent translational investigations suggest that the anticancer activity of IL-9 also extends to some human cancers. Increased T cell-derived IL-9 was proposed to predict the response to anti-PD-1 therapy. Preclinical investigations accordingly revealed that IL-9 could synergize with anti-PD-1 therapy in eliciting anticancer responses. Here, we review the findings suggesting an important contribution of IL-9 in the efficacy of anti-PD-1 therapy and discuss their clinical relevance. We will also discuss the role of host factors like the microbiota and TGFβ in the tumor microenvironment (TME) in the regulation of IL-9 secretion and anti-PD-1 treatment efficacy.

Diverse Role of OX40 on T Cells as a Therapeutic Target for Skin Diseases

OX40 is an important costimulatory molecule for T-cell expansion and survival. Because OX40 is expressed on most T-cell subsets, it is an attractive therapeutic target for a variety of T-cell‒mediated diseases. Clinical trials are already underway for some skin inflammatory diseases. In this review, we present various observations that improve our understanding of how OX40-targeted therapy can be applied for skin inflammatory diseases, such as atopic dermatitis and psoriasis, T helper (Th)2- and Th17-mediated diseases, respectively. The important OX40/OX40L-mediated interaction between T cells and other immune cells is also discussed in terms of skin autoimmune diseases, such as alopecia areata and pemphigus. Regulatory T cells (Tregs) highly express OX40, and the skin harbors a large Treg population; thus, understanding how OX40-targeted treatment acts on Tregs is vital for the development of therapeutic strategies for various skin diseases.

A NF-κB-Based High-Throughput Screening for Immune Adjuvants and Inhibitors

The nuclear factor-κB (NF-κB) family is crucial for regulating immune and inflammatory responses. The activation of the immune cell signaling pathway usually activates NF-κB, causing a protective immune response. NF-κB can also cause excessive inflammatory responses by activating a cascade reaction of pro-inflammatory mediators such as cytokines. In this study, we used an NF-κB luciferase reporter gene system. Out of more than 800 compounds screened, four NF-κB agonists were identified with strong activity at nontoxic concentrations. Subsequently, the adjuvant effect was verified on mouse bone marrow-derived dendritic cells (BMDCs) and macrophages RAW264.7. It was found that fostamatinib (R788) disodium increased the production of IL-6, IL-12p40, and TNF-α, indicating that R788 disodium could induce the maturation of antigen-presenting cells (APCs). In addition, three compounds were screened to significantly inhibit NF-κB at nontoxic doses, including dehydrocostus lactone (DHL)-a known NF-κB inhibitor. The results showed that DHL significantly reduced the release of LPS-induced inflammatory cytokines (including TNF-α, IL-6, and IL-12). Our findings indicate that the NF-κB-based high-throughput screening can be used to discover potential immune adjuvants and anti-inflammatory molecules.

Staphylococcus aureus-derived factors promote human Th9 cell polarization and enhance a transcriptional program associated with allergic inflammation

T helper (Th) 9 cells, characterized by robust secretion of IL-9, have been increasingly associated with allergic diseases. However, whether and how Th9 cells are modulated by environmental stimuli remains poorly understood. In this study, we show that in vitro exposure of human PBMCs or isolated CD4 T-cells to Staphylococcus (S.) aureus-derived factors, including its toxins, potently enhances Th9 cell frequency and IL-9 secretion. Furthermore, as revealed by RNA sequencing analysis, S. aureus increases the expression of Th9-promoting factors at the transcriptional level, such as FOXO1, miR-155, and TNFRSF4. The addition of retinoic acid (RA) dampens the Th9 responses promoted by S. aureus and substantially changes the transcriptional program induced by this bacterium, while also altering the expression of genes associated with allergic inflammation. Together, our results demonstrate a strong influence of microbial and dietary factors on Th9 cell polarization, which may be important in the context of allergy development and treatment.

The Differentially Expressed Genes Responsible for the Development of T Helper 9 Cells From T Helper 2 Cells in Various Disease States: Immuno-Interactomics Study

BACKGROUND

T helper (Th) 9 cells are a novel subset of Th cells that develop independently from Th2 cells and are characterized by the secretion of interleukin (IL)-9. Studies have suggested the involvement of Th9 cells in variable diseases such as allergic and pulmonary diseases (eg, asthma, chronic obstructive airway disease, chronic rhinosinusitis, nasal polyps, and pulmonary hypoplasia), metabolic diseases (eg, acute leukemia, myelocytic leukemia, breast cancer, lung cancer, melanoma, pancreatic cancer), neuropsychiatric disorders (eg, Alzheimer disease), autoimmune diseases (eg, Graves disease, Crohn disease, colitis, psoriasis, systemic lupus erythematosus, systemic scleroderma, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, atopic dermatitis, eczema), and infectious diseases (eg, tuberculosis, hepatitis). However, there is a dearth of information on its involvement in other metabolic, neuropsychiatric, and infectious diseases.

OBJECTIVE

This study aims to identify significant differentially altered genes in the conversion of Th2 to Th9 cells, and their regulating microRNAs (miRs) from publicly available Gene Expression Omnibus data sets of the mouse model using in silico analysis to unravel various pathogenic pathways involved in disease processes.

METHODS

Using differentially expressed genes (DEGs) identified from 2 publicly available data sets (GSE99166 and GSE123501) we performed functional enrichment and network analyses to identify pathways, protein-protein interactions, miR-messenger RNA associations, and disease-gene associations related to significant differentially altered genes implicated in the conversion of Th2 to Th9 cells.

RESULTS

We extracted 260 common downregulated, 236 common upregulated, and 634 common DEGs from the expression profiles of data sets GSE99166 and GSE123501. Codifferentially expressed ILs, cytokines, receptors, and transcription factors (TFs) were enriched in 7 crucial Kyoto Encyclopedia of Genes and Genomes pathways and Gene Ontology. We constructed the protein-protein interaction network and predicted the top regulatory miRs involved in the Th2 to Th9 differentiation pathways. We also identified various metabolic, allergic and pulmonary, neuropsychiatric, autoimmune, and infectious diseases as well as carcinomas where the differentiation of Th2 to Th9 may play a crucial role.

CONCLUSIONS

This study identified hitherto unexplored possible associations between Th9 and disease states. Some important ILs, including CCL1 (chemokine [C-C motif] ligand 1), CCL20 (chemokine [C-C motif] ligand 20), IL-13, IL-4, IL-12A, and IL-9; receptors, including IL-12RB1, IL-4RA (interleukin 9 receptor alpha), CD53 (cluster of differentiation 53), CD6 (cluster of differentiation 6), CD5 (cluster of differentiation 5), CD83 (cluster of differentiation 83), CD197 (cluster of differentiation 197), IL-1RL1 (interleukin 1 receptor-like 1), CD101 (cluster of differentiation 101), CD96 (cluster of differentiation 96), CD72 (cluster of differentiation 72), CD7 (cluster of differentiation 7), CD152 (cytotoxic T lymphocyte-associated protein 4), CD38 (cluster of differentiation 38), CX3CR1 (chemokine [C-X3-C motif] receptor 1), CTLA2A (cytotoxic T lymphocyte-associated protein 2 alpha), CTLA28, and CD196 (cluster of differentiation 196); and TFs, including FOXP3 (forkhead box P3), IRF8 (interferon regulatory factor 8), FOXP2 (forkhead box P2), RORA (RAR-related orphan receptor alpha), AHR (aryl-hydrocarbon receptor), MAF (avian musculoaponeurotic fibrosarcoma oncogene homolog), SMAD6 (SMAD family member 6), JUN (Jun proto-oncogene), JAK2 (Janus kinase 2), EP300 (E1A binding protein p300), ATF6 (activating transcription factor 6), BTAF1 (B-TFIID TATA-box binding protein associated factor 1), BAFT (basic leucine zipper transcription factor), NOTCH1 (neurogenic locus notch homolog protein 1), GATA3 (GATA binding protein 3), SATB1 (special AT-rich sequence binding protein 1), BMP7 (bone morphogenetic protein 7), and PPARG (peroxisome proliferator-activated receptor gamma, were able to identify significant differentially altered genes in the conversion of Th2 to Th9 cells. We identified some common miRs that could target the DEGs. The scarcity of studies on the role of Th9 in metabolic diseases highlights the lacunae in this field. Our study provides the rationale for exploring the role of Th9 in various metabolic disorders such as diabetes mellitus, diabetic nephropathy, hypertensive disease, ischemic stroke, steatohepatitis, liver fibrosis, obesity, adenocarcinoma, glioblastoma and glioma, malignant neoplasm of stomach, melanoma, neuroblastoma, osteosarcoma, pancreatic carcinoma, prostate carcinoma, and stomach carcinoma.

XIAP and PHB1 Regulate Anoikis through Competitive Binding to TRAF6

Anoikis resistance is a prerequisite for circulating tumor cells to survive. However, the mechanism underlying anoikis resistance is poorly understood. In the current study, the effect of TNF receptor-associated factor 6 (TRAF6)-induced NF-kB activation on anoikis susceptibility in tumor cells was evaluated. Differential TRAF6-binding proteins in anoikis-sensitive versus anoikis-resistant tumor cells were screened by LC/MS-MS analysis. The effects of TRAF6-binding proteins on the stability of TRAF6, the activation of NF-kB signaling and anoikis susceptibility in tumor cells were detected. We found that the loss of TRAF6 expression is an important molecular event linked to anoikis. X-linked inhibitor of apoptosis protein (XIAP), an E3 ligase, can bind, ubiquitinate, and degrade TRAF6 and may lead to inactivation of NF-κB signaling and anoikis sensitivity. High expression of prohibitin 1 (PHB1) competes with XIAP for binding to TRAF6 and confers anoikis resistance to tumor cells. PHB1 and TRAF6 knockdown eliminated tumor cells from the circulation in vivo. Significant correlations between elevated PHB1 and TRAF6 expression and distant metastasis were observed in patients with oral cancer. Collectively, we elucidated a novel mechanism governing anoikis. Our data also indicated that TRAF6 and PHB1 are potential therapeutic targets for tumor cells disseminating in the circulation.

IMPLICATIONS

Our data implicate that PHB1 competes with XIAP for binding to TRAF6 and confers anoikis resistance to tumor cells.

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

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

Neuroinflammation: Extinguishing a blaze of T cells

Inflammation is a biological process that dynamically alters the surrounding microenvironment, including participating immune cells. As a well-protected organ surrounded by specialized barriers and with immune privilege properties, the central nervous system (CNS) tightly regulates immune responses. Yet in neuroinflammatory conditions, pathogenic immunity can disrupt CNS structure and function. T cells in particular play a key role in promoting and restricting neuroinflammatory responses, while the inflamed CNS microenvironment can influence and reshape T cell function and identity. Still, the contraction of aberrant T cell responses within the CNS is not well understood. Using autoimmunity as a model, here we address the contribution of CD4 T helper (Th) cell subsets in promoting neuropathology and disease. To address the mechanisms antagonizing neuroinflammation, we focus on the control of the immune response by regulatory T cells (Tregs) and describe the counteracting processes that preserve their identity under inflammatory challenges. Finally, given the influence of the local microenvironment on immune regulation, we address how CNS-intrinsic signals reshape T cell function to mitigate abnormal immune T cell responses.

RelB contributes to the survival, migration and lymphomagenesis of B cells with constitutively active CD40 signaling

Activation of CD40-signaling contributes to the initiation, progression and drug resistance of B cell lymphomas. We contributed to this knowledge by showing that constitutive CD40-signaling in B cells induces B cell hyperplasia and finally B cell lymphoma development in transgenic mice. CD40 activates, among others, the non-canonical NF-ĸB signaling, which is constitutively activated in several human B cell lymphomas and is therefore presumed to contribute to lymphopathogenesis. This prompted us to study the regulatory role of the non-canonical NF-ĸB transcription factor RelB in lymphomagenesis. To this end, we crossed mice expressing a constitutively active CD40 receptor in B cells with conditional RelB-KO mice. Ablation of RelB attenuated pre-malignant B cell expansion, and resulted in an impaired survival and activation of long-term CD40-stimulated B cells. Furthermore, we found that hyperactivation of non-canonical NF-кB signaling enhances the retention of B cells in the follicles of secondary lymphoid organs. RNA-Seq-analysis revealed that several genes involved in B-cell migration, survival, proliferation and cytokine signaling govern the transcriptional differences modulated by the ablation of RelB in long-term CD40-stimulated B cells. Inactivation of RelB did not abrogate lymphoma development. However, lymphomas occurred with a lower incidence and had a longer latency period. In summary, our data suggest that RelB, although it is not strictly required for malignant transformation, accelerates the lymphomagenesis of long-term CD40-stimulated B cells by regulating genes involved in migration, survival and cytokine signaling.

IL-9 Producing Tumor-Infiltrating Lymphocytes and Treg Subsets Drive Immune Escape of Tumor Cells in Non-Small Cell Lung Cancer

Although lung cancer is the leading cause of cancer deaths worldwide, the mechanisms how lung cancer cells evade the immune system remain incompletely understood. Here, we discovered IL-9-dependent signaling mechanisms that drive immune evasion in non-small cell lung cancer (NSCLC). We found increased IL-9 and IL-21 production by T cells in the tumoral region of the lung of patients with NSCLC, suggesting the presence of Th9 cells in the lung tumor microenvironment. Moreover, we noted IL-9 producing Tregs in NSCLC. IL-9 target cells in NSCLC consisted of IL-9R+ tumor cells and tumor-infiltrating lymphocytes. In two murine experimental models of NSCLC, and in vitro, IL-9 prevented cell death and controlled growth of lung adenocarcinoma cells. Targeted deletion of IL-9 resulted in successful lung tumor rejection in vivo associated with an induction of IL-21 and reduction of Treg cells. Finally, anti-IL-9 antibody immunotherapy resulted in suppression of tumor development even in established experimental NSCLC and was associated with reduced IL-10 production in the lung. In conclusion, our findings indicate that IL-9 drives immune escape of lung tumor cells via effects on tumor cell survival and tumor infiltrating T cells. Thus, strategies blocking IL-9 emerge as a new approach for clinical therapy of lung cancer.

Pathogen size alters C-type lectin receptor signaling in dendritic cells to influence CD4 Th9 cell differentiation

Dectin-1 recognizes β-glucan in fungal cell walls, and activation of Dectin-1 in dendritic cells (DCs) influences immune responses against fungi. Although many studies have shown that DCs activated via Dectin-1 induce different subsets of T helper cells according to different cytokine milieus, the mechanisms underlying such differences remain unknown. By harnessing polymorphic Candida albicans and polystyrene beads of different sizes, we find that target size influences production of cytokines that control differentiation of T helper cell subsets. Hyphal C. albicans and large beads activate DCs but cannot be phagocytosed due to their sizes, which prolongs the duration of Dectin-1 signaling. Transcriptomic analysis reveals that expression of Il33 is significantly increased by larger targets, and increased IL-33 expression promotes T_H9 responses. Expression of IL-33 is regulated by the Dectin-1-SYK-PLCγ-CARD9-ERK pathway. Altogether, our study demonstrates that size of fungi can be a determining factor in how DCs induce context-appropriate adaptive immune responses.

Oh et al. show that dendritic cells exposed to C. albicans hyphae more strongly induce IL-9-producing T cells compared with cells exposed to yeast. They find that this T_H9 response is driven in large part by Dectin-1 sensing microbe size, leading to elevated production of IL-33.

CD4 T cell-intrinsic STING signaling controls the differentiation and effector functions of TH1 and TH9 cells

Background

While stimulator of interferon genes (STING) activation in innate immune cells of the tumor microenvironment can result in CD8 T cell-dependent antitumor immunity, whether STING signaling affects CD4 T-cell responses remains elusive.

Methods

Here, we tested whether STING activation modulated the effector functions of CD4 T cells in vivo by analyzing tumor-infiltrating CD4 T cells and evaluating the contribution of the CD4 T cell-derived cytokines in the antitumor activity of the STING ligand 2′3′-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) in two mouse tumor models. We performed ex vivo experiments to assess the impact of STING activation on CD4 T-cell differentiation and investigate the underlying molecular mechanisms. Finally, we tested whether STING activation enhances T_H9 cell antitumor activity against mouse melanoma upon adoptive transfer.

Results

We found that activation of STING signaling cell-intrinsically enhances the differentiation and antitumor functions of T_H1 and T_H9 cells by increasing their respective production of interferon gamma (IFN-γ) and interleukin-9. IRF3 and type I interferon receptors (IFNARs) are required for the STING-driven enhancement of T_H1 cell differentiation. However, STING activation favors T_H9 cell differentiation independently of the IFNARs/IRF3 pathway but through mammalian target of rapamycin (mTOR) signaling, underscoring that STING activation differentially affects the fate of distinct CD4 T-cell subsets. The therapeutic effect of STING activation relies on T_H1 and T_H9-derived cytokines, and STING activation enhances the antitumor activity of T_H9 cells upon adoptive transfer.

Conclusion

Our results reveal the STING signaling pathway as a therapeutic target to boost CD4 T-cell effector functions and antitumor immunity.

IL-1β promotes IL-9-producing Th cell differentiation in IL-2-limiting conditions through the inhibition of BCL6

IL-9-producing CD4⁺ T helper cells, termed Th9 cells, differentiate from naïve precursor cells in response to a combination of cytokine and cell surface receptor signals that are elevated in inflamed tissues. After differentiation, Th9 cells accumulate in these tissues where they exacerbate allergic and intestinal disease or enhance anti-parasite and anti-tumor immunity. Previous work indicates that the differentiation of Th9 cells requires the inflammatory cytokines IL-4 and TGF-β and is also dependent of the T cell growth factor IL-2. While the roles of IL-4 and TGF-β-mediated signaling are relatively well understood, how IL-2 signaling contributes to Th9 cell differentiation outside of directly inducing the Il9 locus remains less clear. We show here that murine Th9 cells that differentiate in IL-2-limiting conditions exhibit reduced IL-9 production, diminished NF-kB activation and a reduced NF-kB-associated transcriptional signature, suggesting that IL-2 signaling is required for optimal NF-kB activation in Th9 cells. Interestingly, both IL-9 production and the NF-kB transcriptional signature could be rescued by addition of the NF-kB-activating cytokine IL-1β to IL-2-limiting cultures. IL-1β was unique among NF-kB-activating factors in its ability to rescue Th9 differentiation as IL-2 deprived Th9 cells selectively induced IL-1R expression and IL-1β/IL-1R1 signaling enhanced the sensitivity of Th9 cells to limiting amounts of IL-2 by suppressing expression of the Th9 inhibitory factor BCL6. These data shed new light on the intertwined nature of IL-2 and NF-kB signaling pathways in differentiating Th cells and elucidate the potential mechanisms that promote Th9 inflammatory function in IL-2-limiting conditions.

NF-κB signaling in inflammation and cancer

Since nuclear factor of κ-light chain of enhancer-activated B cells (NF-κB) was discovered in 1986, extraordinary efforts have been made to understand the function and regulating mechanism of NF-κB for 35 years, which lead to significant progress. Meanwhile, the molecular mechanisms regulating NF-κB activation have also been illuminated, the cascades of signaling events leading to NF-κB activity and key components of the NF-κB pathway are also identified. It has been suggested NF-κB plays an important role in human diseases, especially inflammation-related diseases. These studies make the NF-κB an attractive target for disease treatment. This review aims to summarize the knowledge of the family members of NF-κB, as well as the basic mechanisms of NF-κB signaling pathway activation. We will also review the effects of dysregulated NF-κB on inflammation, tumorigenesis, and tumor microenvironment. The progression of the translational study and drug development targeting NF-κB for inflammatory diseases and cancer treatment and the potential obstacles will be discussed. Further investigations on the precise functions of NF-κB in the physiological and pathological settings and underlying mechanisms are in the urgent need to develop drugs targeting NF-κB for inflammatory diseases and cancer treatment, with minimal side effects.

Interplay Between Non-Canonical NF-κB Signaling and Hepatitis B Virus Infection

The non-canonical nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway is an important component of NF-κB transcription complex. Activation of this pathway mediates the development and function of host immune system involved in inflammation and viral infection. During hepatitis B virus (HBV) infection, there is a complex interaction between infected hepatocytes and the immune cells, which can hinder antiviral immune responses and is associated with pathological changes in liver tissue. Consistently, the host immune system is closely related to the severity of liver damage and the level of viral replication. Previous studies indicated that the non-canonical NF-κB signaling pathway was affected by HBV and might play an important regulatory role in the antiviral immunity. Therefore, systematically elucidating the interplay between HBV and non-canonical NF-κB signaling will contribute the discovery of more potential therapeutic targets and novel drugs to treat HBV infection.

Tumor rejection in Cblb -/- mice depends on IL-9 and Th9 cells

BACKGROUND

Casitas B lymphoma-b (Cbl-b) is a central negative regulator of cytotoxic T and natural killer (NK) cells and functions as an intracellular checkpoint in cancer. In particular, Th9 cells support mast cell activation, promote dendritic cell recruitment, enhance the cytolytic function of cytotoxic T lymphocytes and NK cells, and directly kill tumor cells, thereby contributing to tumor immunity. However, the role of Cbl-b in the differentiation and antitumor function of Th9 cells is not sufficiently resolved.

METHODS

Using Cblb ^-/- mice, we investigated the effect of knocking out Cblb on the differentiation process and function of different T helper cell subsets, focusing on regulatory T cell (Treg) and Th9 cells. We applied single-cell RNA (scRNA) sequencing of in vitro differentiated Th9 cells to understand how Cbl-b shapes the transcriptome and regulates the differentiation and function of Th9 cells. We transferred tumor-model antigen-specific Cblb ^-/- Th9 cells into melanoma-bearing mice and assessed tumor control in vivo. In addition, we blocked interleukin (IL)-9 in melanoma cell-exposed Cblb ^-/- mice to investigate the role of IL-9 in tumor immunity.

RESULTS

Here, we provide experimental evidence that Cbl-b acts as a rheostat favoring Tregs at the expense of Th9 cell differentiation. Cblb ^-/- Th9 cells exert superior antitumor activity leading to improved melanoma control in vivo. Accordingly, blocking IL-9 in melanoma cell-exposed Cblb ^-/- mice reversed their tumor rejection phenotype. Furthermore, scRNA sequencing of in vitro differentiated Th9 cells from naïve T cells isolated from wildtype and Cblb ^-/- animals revealed a transcriptomic basis for increased Th9 cell differentiation.

CONCLUSION

We established IL-9 and Th9 cells as key antitumor executers in Cblb ^-/- animals. This knowledge may be helpful for the future improvement of adoptive T cell therapies in cancer.

A chimeric antigen receptor with antigen-independent OX40 signaling mediates potent antitumor activity

Although chimeric antigen receptor (CAR)-modified T cells have shown great success in the treatment of B cell malignancies, this approach has limited efficacy in patients with solid tumors. Various modifications in CAR structure have been explored to improve this efficacy, including the incorporation of two costimulatory domains. Because costimulatory signals are transduced together with T cell receptor signals during T cell activation, we engineered a type of CAR-T cells with a costimulatory signal that was activated independently from the tumor antigen to recapitulate physiological stimulation. We screened 12 costimulatory receptors to identify OX40 as the most effective CAR-T function enhancer. Our data indicated that these new CAR-T cells showed superior proliferation capability compared to current second-generation CAR-T cells. OX40 signaling reduced CAR-T cell apoptosis through up-regulation of genes encoding Bcl-2 family members and enhanced proliferation through increased activation of the NF-κB (nuclear factor κB), MAPK (mitogen-activated protein kinase), and PI3K-AKT (phosphoinositide 3-kinase to the kinase AKT) pathways. OX40 signaling not only enhanced the cytotoxicity of CAR-T cells but also reduced exhaustion markers, thereby maintaining their function in immunosuppressive tumor microenvironments. In mouse tumor models and in patients with metastatic lymphoma, these CAR-T cells exhibited robust amplification and antitumor activity. Our findings provide an alternative option for CAR-T optimization with the potential to overcome the challenge of treating solid tumors.

The OX40/OX40L Axis Regulates T Follicular Helper Cell Differentiation: Implications for Autoimmune Diseases

T Follicular helper (Tfh) cells, a unique subset of CD4+ T cells, play an essential role in B cell development and the formation of germinal centers (GCs). Tfh differentiation depends on various factors including cytokines, transcription factors and multiple costimulatory molecules. Given that OX40 signaling is critical for costimulating T cell activation and function, its roles in regulating Tfh cells have attracted widespread attention. Recent data have shown that OX40/OX40L signaling can not only promote Tfh cell differentiation and maintain cell survival, but also enhance the helper function of Tfh for B cells. Moreover, upregulated OX40 signaling is related to abnormal Tfh activity that causes autoimmune diseases. This review describes the roles of OX40/OX40L in Tfh biology, including the mechanisms by which OX40 signaling regulates Tfh cell differentiation and functions, and their close relationship with autoimmune diseases.

Inhibiting OX40 Restores Regulatory T-Cell Function and Suppresses Inflammation in Pulmonary Sarcoidosis

BACKGROUND

Pulmonary sarcoidosis (PS) is a noncaseating granulomatous disease of unknown origin. Despite conflicting reports, it is considered that the regulatory T (Treg) cells are functionally impaired in PS, but the underlying mechanisms remain unclear. OX40, a pivotal costimulatory molecule, is essential for T-cell functions and memory development, but its impact on Treg cells is ambiguous.

RESEARCH QUESTION

Does the OX40 pathway influence the suppressive functions of Treg cells in PS?

STUDY DESIGN AND METHODS

Fifty treatment-naïve patients with PS and 30 healthy control participants were recruited for this study. Polychromatic flow cytometry-based immunologic assays were performed to enumerate effector T helper (Th) cells and Treg cells along with their functions. Using real-time polymerase chain reaction analysis, small interfering RNA, and pharmacologic inhibitors, the impact of OX40 on Treg cell function was investigated.

RESULTS

We observed enrichment of Th-9 cells perhaps for the first time along with Th-1, Th-17, and Treg cells in patients' BAL fluid (BALF) compared with peripheral blood. However, Treg cells were observed to be functionally defective at the pathological site. We observed higher expression of OX40 on both T effector (CD4⁺Foxp3^-) and Treg (CD4⁺Foxp3⁺) cells obtained from the BALF of patients with PS. However, OX40 exerted contrasting impact on these T-cell subsets, enhancing effector T-cell functions (interferon γ, tumor necrosis factor α) while inhibiting Treg cell function (IL-10, transforming growth factor β). OX40 silencing or blocking on Treg cells resulted in restoration of their impaired functions.

INTERPRETATION

We propose that inhibiting the OX40 pathway may constitute a therapeutic strategy for controlling inflammatory T cells by restoring Treg cell functions in patients with PS.

Harnessing TH9 cells in cancer immunotherapy

CD4 T cell effector subsets not only profoundly affect cancer progression, but recent evidence also underscores their critical contribution to the anticancer efficacy of immune checkpoint inhibitors. In 2012, the two seminal studies suggested the superior antimelanoma activity of T_H9 cells over other T cell subsets upon adoptive T cell transfer. While these findings provided great impetus to investigate further the unique functions of T_H9 cells and explore their relevance in cancer immunotherapy, the following questions still remain outstanding: are T_H9 cell anticancer functions restricted to melanoma? What are the factors favouring T_H9 cell effector functions? What is the contribution of T_H9 cells to cancer immunotherapy treatments? Can T_H9 cells be identified in humans and, if so, what is their clinical relevance? By reviewing the studies addressing these questions, we will discuss how T_H9 cells could be therapeutically harnessed for cancer immunotherapy strategies.

IL-9 and IL-10 Single-Nucleotide Variants and Serum Levels in Age-Related Macular Degeneration in the Caucasian Population

Considering the immunological impairment in age-related macular degeneration (AMD), we aimed to determine the associations of IL-9 rs1859430, rs2069870, rs11741137, rs2069885, and rs2069884 and IL-10 rs1800871, rs1800872, and rs1800896 polymorphisms and their haplotypes, as well as the serum levels of IL-9 and IL-10 with AMD. 1209 participants were enrolled in our study. SNPs were genotyped using TaqMan SNP genotyping assays by real-time PCR method. IL-9 and IL-10 serum levels were evaluated using ELISA kits. Our study results have shown that haplotypes A-G-C-G-G and G-A-T-A-T of IL-9 SNPs are associated with the decreased odds of early AMD occurrence (p = 0.035 and p = 0.015, respectively). A set of rare haplotypes was associated with the decreased odds of exudative AMD occurrence (p = 0.033). Also, IL-10 serum levels were lower in exudative AMD than in controls (p = 0.049), patients with early AMD (p = 0.017), and atrophic AMD (p = 0.008). Furthermore, exudative AMD patients with IL-10 rs1800896 CT and TT genotypes had lower IL-10 serum concentrations than those with wild-type (CC) genotype (p = 0.048). In conclusion, our study suggests that IL-10 serum levels can be associated with a minor allele at IL-10 rs1800896 and exudative AMD. The haplotypes of IL-9 SNPs were also associated with the decreased odds of early and exudative AMD.

Innate Lymphoid Cells and Adaptive Immune Cells Cross-Talk: A Secret Talk Revealed in Immune Homeostasis and Different Inflammatory Conditions

The inflammatory immune response has evolved to protect the host from different pathogens, allergens, and endogenous death or damage-associated molecular patterns. Both innate and adaptive immune components are crucial in inducing an inflammatory immune response depending on the stimulus type and its duration of exposure or the activation of the primary innate immune response. As the source of inflammation is removed, the aggravated immune response comes to its homeostatic level. However, the failure of the inflammatory immune response to subside to its normal level generates chronic inflammatory conditions, including autoimmune diseases and cancer. Innate lymphoid cells (ILCs) are newly discovered innate immune cells, which are present in abundance at mucosal surfaces, including lungs, gastrointestinal tract, and reproductive tract. Also, they are present in peripheral blood circulation, skin, and lymph nodes. They play a crucial role in generating the pro-inflammatory immune response during diverse conditions. On the other hand, adaptive immune cells, including different types of T and B cells are major players in the pathogenesis of autoimmune diseases (type 1 diabetes mellitus, rheumatoid arthritis, psoriasis, and systemic lupus erythematosus, etc.) and cancers. Thus the article is designed to discuss the immunological role of different ILCs and their interaction with adaptive immune cells in maintaining the immune homeostasis, and during inflammatory autoimmune diseases along with other inflammatory conditions (excluding pathogen-induced inflammation), including cancer, graft-versus-host diseases, and human pregnancy.

OX40L/OX40 Signal Promotes IL-9 Production by Mucosal MAIT Cells During Helicobacter pylori Infection

Mucosal associated invariant T (MAIT) cells play a critical role in Helicobacter pylori (H. pylori)-induced gastritis by promoting mucosal inflammation and aggravating mucosal injuries (1, 2). However, the underlying mechanism and key molecules involved are still uncertain. Here we identified OX40, a co-stimulatory molecule mainly expressed on T cells, as a critical regulator to promote proliferation and IL-9 production by MAIT cells and facilitate mucosal inflammation in H. pylori-positive gastritis patients. Serum examination revealed an increased level of IL-9 in gastritis patients. Meanwhile, OX40 expression was increased in mucosal MAIT cells, and its ligand OX40L was also up-regulated in mucosal dendritic cells (DCs) of gastritis patients, compared with healthy controls. Further results demonstrated that activation of the OX40/OX40L pathway promoted IL-9 production by MAIT cells, and MAIT cells displayed a highly-activated phenotype after the cross-linking of OX40 and OX40L. Moreover, the level of IL-9 produced by MAIT cells was positively correlated with inflammatory indexes in the gastric mucosa, suggesting the potential role of IL-9-producing MAIT cells in mucosal inflammation. Taken together, we elucidated that OX40/OX40L axis promoted mucosal MAIT cell proliferation and IL-9 production in H. pylori-induced gastritis, which may provide potential targeting strategies for gastritis treatment.

Critical Roles of Balanced T Helper 9 Cells and Regulatory T Cells in Allergic Airway Inflammation and Tumor Immunity

CD4⁺T helper (Th) cells are important mediators of immune responses in asthma and cancer. When counteracted by different classes of pathogens, naïve CD4⁺T cells undergo programmed differentiation into distinct types of Th cells. Th cells orchestrate antigen-specific immune responses upon their clonal T-cell receptor (TCR) interaction with the appropriate peptide antigen presented on MHC class II molecules expressed by antigen-presenting cells (APCs). T helper 9 (Th9) cells and regulatory T (Treg) cells and their corresponding cytokines have critical roles in tumor and allergic immunity. In the context of asthma and cancer, the dynamic internal microenvironment, along with chronic inflammatory stimuli, influences development, differentiation, and function of Th9 cells and Treg cells. Furthermore, the dysregulation of the balance between Th9 cells and Treg cells might trigger aberrant immune responses, resulting in development and exacerbation of asthma and cancer. In this review, the development, differentiation, and function of Th9 cells and Treg cells, which are synergistically regulated by various factors including cytokine signals, transcriptional factors (TFs), costimulatory signals, microenvironment cues, metabolic pathways, and different signal pathways, will be discussed. In addition, we focus on the recent progress that has helped to achieve a better understanding of the roles of Th9 cells and Treg cells in allergic airway inflammation and tumor immunity. We also discuss how various factors moderate their responses in asthma and cancer. Finally, we summarize the recent findings regarding potential mechanisms for regulating the balance between Th9 and Treg cells in asthma and cancer. These advances provide opportunities for novel therapeutic strategies that are aimed at reestablishing the balance of these cells in the diseases.

Noncanonical NF-κB Signaling Pathway in Liver Diseases

The noncanonical NF-κB signaling pathway is an important branch of NF-κB signaling. It is involved in regulating multiple important biological processes, including inflammation and host immune response. A central adaptor protein of the noncanonical NF-κB pathway is NF-κB-inducing kinase (NIK), which activates the downstream kinase IKKα to process p100 to p52, thereby forming the RelB/p52 heterodimer to initiate the expression of target genes. Currently, many specific inhibitors and monoclonal antibodies targeting or triggering this pathway are being developed and tested for various diseases, including cancers, autoimmune diseases, and virus infection. Given that aberrant activation of the noncanonical NF-κB pathway is frequently observed in various liver diseases, targeting this pathway may be a promising therapeutic strategy to alleviate liver inflammation. Moreover, activation of this pathway may contribute to the antiviral immune response and promote the clearance of persistent hepatotropic virus infection. Here, we review the role of the noncanonical NF-κB pathway in the occurrence and development of different liver diseases, and discuss the potency and application of modulating the noncanonical NF-κB pathway for treatment of these liver diseases.

Epimedin C modulates the balance between Th9 cells and Treg cells through negative regulation of noncanonical NF-κB pathway and MAPKs activation to inhibit airway inflammation in the ovalbumin-induced murine asthma model

Allergic asthma is a common airway inflammatory disease and mainly caused by abnormal immune responses to allergens and viruses. The precise mechanisms of airway inflammation and airway hyper-responsiveness (AHR) are still not completely understood. CD4⁺ helper T cells (Th cells) serve as critical regulators of allergic immunity. The imbalance between T helper 9 (Th9) cells and forkhead box protein 3 (Foxp3)⁺ regulatory T (Treg) cells may contribute to airway inflammation in asthma. Epimedin C, a dominant compound isolated from Herba Epimedii, has shown anti-inflammatory effects and the immunoregulatory activity, such as increase of lymphocyte proliferation. However, the protective role of epimedin C in an experimental model of ovalbumin (OVA)-induced allergic airway inflammation and the underlying mechanism remain unknown. Female BALB/c mice were sensitized by intraperitoneal injection (i.p.) of OVA plus aluminum hydroxide (Alum) and subsequently challenged with an aerosol of 3% OVA in saline. Mice were treated with different concentrations of epimedin C (20 mg/kg/d, 40 mg/kg/d, 80 mg/kg/d) for 4 weeks. Experimental endpoints were evaluated via the analysis of AHR to acetyl-β-methacholine (Mch), differential inflammatory cell counts, concentrations of cytokines interleukin-9 (IL-9), IL-4 and IL-10 in bronchoalveolar lavage fluid (BALF), serum OVA-specific IgE level, as well as airway inflammation, mucus secretion and collagen deposition in mice. Mechanistically, we investigated the percentages of Th9 cells and Treg cells, as well as mRNA levels of IL-9 and transcription factor Foxp3 in lungs. Furthermore, the proteins expression of nuclear factor-κB (NF-κB) family members p105/p50, RelA, p100/p52 and RelB, as well as mitogen-activated protein kinase (MAPK) family members extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 MAPK was detected. Epimedin C dose-dependently attenuated AHR, airway inflammation, mucus hypersecretion and collagen deposition in OVA-induced murine asthma model. The expression levels of IL-9, IL-4 and OVA-specific IgE were significantly decreased while IL-10 was increased by epimedin C. We further confirmed that epimedin C decreased the percentage of lung Th9 cells with lower mRNA expression of IL-9 and increased the percentage of lung Treg cells with higher mRNA expression of Foxp3. In addition, epimedin C dose-dependently decreased the protein levels of p52, RelB, phosphorylation of ERK1/2 and p38 MAPK which are pivotal to the development of Th9 cells and Treg cells. Collectively, epimedin C could inhibit pathophysiological features of asthma by reconstruction of the balance between Th9 cells and Treg cells through regulation of the noncanonical NF-κB p52/RelB pathway and MAPKs activation. These findings suggest epimedin C as a potential remedy for inflammatory airway diseases.

NF-κB in Cancer Immunity: Friend or Foe?

The emergence of immunotherapies has definitely proven the tight relationship between malignant and immune cells, its impact on cancer outcome and its therapeutic potential. In this context, it is undoubtedly critical to decipher the transcriptional regulation of these complex interactions. Following early observations demonstrating the roles of NF-κB in cancer initiation and progression, a series of studies converge to establish NF-κB as a master regulator of immune responses to cancer. Importantly, NF-κB is a family of transcriptional activators and repressors that can act at different stages of cancer immunity. In this review, we provide an overview of the selective cell-intrinsic contributions of NF-κB to the distinct cell types that compose the tumor immune environment. We also propose a new view of NF-κB targeting drugs as a new class of immunotherapies for cancer.

Targeting ubiquitin signaling for cancer immunotherapy

Cancer immunotherapy has become an attractive approach of cancer treatment with tremendous success in treating various advanced malignancies. The development and clinical application of immune checkpoint inhibitors represent one of the most extraordinary accomplishments in cancer immunotherapy. In addition, considerable progress is being made in understanding the mechanism of antitumor immunity and characterizing novel targets for developing additional therapeutic approaches. One active area of investigation is protein ubiquitination, a post-translational mechanism of protein modification that regulates the function of diverse immune cells in antitumor immunity. Accumulating studies suggest that E3 ubiquitin ligases and deubiquitinases form a family of potential targets to be exploited for enhancing antitumor immunity in cancer immunotherapy.

miR-143/145 inhibits Th9 cell differentiation by targeting NFATc1

Th9 cells are a defined CD4+ helper T cell subgroup found to promote or suppress oncogenesis in a context-dependent manner. How microRNAs (miRNAs) shape Th9 cell functionality, however, remains to be studied. Herein, we determined that miR-143/145 is downregulated during Th9 differentiation. When these miRNAs were upregulated, this inhibited Th9 differentiation, proliferation, and IL-9 production. Overexpressing miR-143/145 in Th9 cells further suppressed NFATc1 expression at the protein and mRNA level, whereas the opposite phenotype was observed when miR-143/145 was downregulated in these cells. NFATc1 silencing markedly inhibited Th9 cell differentiation, whereas overexpressing this transcription factor was sufficient to reverse miR-143/145-associated phenotypes in these cells. These findings thus indicate that the ability of miR-143/145 to inhibit Th9 cell differentiation is attributable to their ability to target and suppress NFATc1 expression. Overall, our results highlight a novel mode of action whereby miR-143/145 controls Th9 differentiation, suggesting that this pathway may be amenable to therapeutic targeting in the context of anti-cancer treatment in the future.

Regulation of mRNA stability by RBPs and noncoding RNAs contributing to the pathogenicity of Th17 cells

Th17 cells remain one of the most important subsets of T cells in numerous autoimmune and chronic inflammatory diseases. Posttranscriptional regulation (PTR), especially mRNA stability, has recently emerged as an important mechanism that controls the fate of Th17 cells. This review summarizes the current knowledge on RNA-binding proteins (RBPs), microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) that induce mRNA stability changes and their roles in mediating the differentiation, proliferation, function, and migration of Th17 cells. In addition, we summarize the role of RNA modifications and nonsense-mediated mRNA decay (NMD) in Th17 cells. Ongoing research will help to identify practical applications for the regulation of mRNA stability and provide potential targets to prevent and treat Th17-related autoimmune diseases.

Mechanism by which TRAF6 Participates in the Immune Regulation of Autoimmune Diseases and Cancer

Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), an E3 ubiquitin ligase, is a signal transduction molecule shared by the interleukin-1 receptor (IL-1R)/Toll-like receptor (TLR) family and the TNFR superfamily. TRAF6 has a unique TRAF domain and RING finger domain that mediate intracellular signaling events. In the immune system, TRAF6-mediated signaling has been shown to be critical for the development, homeostasis, and activation of a variety of immune cells, including B cells, T cells, dendritic cells, and macrophages. Although the pathogenesis and etiology of autoimmune diseases and cancer are not fully understood, it is worth noting that existing studies have shown that TRAF6 is involved in the pathogenesis and development of a variety of these diseases. Herein, we reviewed the role of TRAF6 in certain immune cells, as well as the function and potential effect of TRAF6 in autoimmune diseases and cancer. Our review indicates that TRAF6 may be a novel target for autoimmune diseases and cancer.