Reciprocal regulation of the Il9 locus by counteracting activities of transcription factors IRF1 and IRF4

ETS translocation variant 5 (ETV5) promotes CD4+ T cell-mediated intestinal inflammation and fibrosis in inflammatory bowel diseases

E26 transformation-specific translocation variant 5 (ETV5) has been implicated in the pathogenesis of inflammatory bowel diseases (IBD). However, the exact roles of ETV5 in regulating CD4+ T cell-mediated intestinal inflammation and fibrosis formation remain unclear. Here, we reveal that ETV5 overexpression induced interleukin (IL)-9 and its transcription factor IRF4 expression in IBD CD4+ T cells under T helper type 9 (Th9) cells-polarizing conditions. The silencing of IRF4 inhibited ETV5-induced IL-9 expression. CD4+ T cell-specific ETV5 deletion ameliorated intestinal inflammation and fibrosis in trinitrobenzene sulfonic acid (TNBS)-induced experimental colitis and CD4+ T cell-transferred recombination-activating gene-1 knockout (Rag1-/-) colitis mice, characterized by less CD4+ T cell infiltration and lower fibroblast activation and collagen deposition in the colonic tissues. Furthermore, IL-9 treatment aggressive TNBS-induced intestinal fibrosis in CD4+ T cell-specific ETV5 deletion and wild-type control mice. In vitro, human intestinal fibroblasts cocultured with ETV5 overexpressed-Th9 cells expressed higher levels of collagen I and III, whereas an inclusion of anti-IL-9 antibody could reverse this effect. Ribonucleic acid sequencing analysis demonstrated that IL-9 upregulated TAF1 expression in human intestinal fibroblasts. Clinical data showed that number of α-smooth muscle actin+TAF1+ fibroblasts are higher in inflamed mucosa of patients with IBD. Importantly, TAF1 small interfering ribonucleic acid treatment suppressed IL-9-mediated profibrotic effect in vitro. These findings reveal that CD4+ T cell-derived ETV5 promotes intestinal inflammation and fibrosis through upregulating IL-9-mediated intestinal inflammatory and fibrotic response in IBD. Thus, the ETV5/IL-9 signal pathway in T cells might represent a novel therapeutic target for intestinal inflammation and fibrosis in IBD.

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.

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.

A Interacting Model: How TRIM21 Orchestrates with Proteins in Intracellular Immunity

Tripartite motif-containing protein 21 (TRIM21), identified as both a cytosolic E3 ubiquitin ligase and FcR (Fragment crystallizable receptor), primarily interacts with proteins via its PRY/SPRY domains and promotes their proteasomal degradation to regulate intracellular immunity. But how TRIM21 involves in intracellular immunity still lacks systematical understanding. Herein, it is probed into the TRIM21-related literature and raises an interacting model about how TRIM21 orchestrates proteins in cytosol. In this novel model, TRIM21 generally interacts with miscellaneous protein in intracellular immunity in two ways: For one, TRIM21 solely plays as an E3, ubiquitylating a glut of proteins that contain specific interferon-regulatory factor, nuclear transcription factor kappaB, virus sensors and others, and involving inflammatory responses. For another, TRIM21 serves as both E3 and specific FcR that detects antibody-complexes and facilitates antibody destroying target proteins. Correspondingly delineated as Fc-independent signaling and Fc-dependent signaling in this review, how TRIM21's interactions contribute to intracellular immunity, expecting to provide a systematical understanding of this important protein and invest enlightenment for further research on the pathogenesis of related diseases and its prospective application is elaborated.

CD4+ T-cell subsets in autoimmune hepatitis: A review

Autoimmune hepatitis (AIH) is a chronic autoimmune liver disease that can lead to hepatocyte destruction, inflammation, liver fibrosis, cirrhosis, and liver failure. The diagnosis of AIH requires the identification of lymphoblast cell interface hepatitis and serum biochemical abnormalities, as well as the exclusion of related diseases. According to different specific autoantibodies, AIH can be divided into AIH-1 and AIH-2. The first-line treatment for AIH is a corticosteroid and azathioprine regimen, and patients with liver failure require liver transplantation. However, the long-term use of corticosteroids has obvious side effects, and patients are prone to relapse after drug withdrawal. Autoimmune diseases are characterized by an imbalance in immune tolerance of self-antigens, activation of autoreactive T cells, overactivity of B cells, and increased production of autoantibodies. CD4+ T cells are key players in adaptive immunity and can secrete cytokines, activate B cells to produce antibodies, and influence the cytotoxicity of CD8+ T cells. According to their characteristics, CD4+ T cells can be divided into different subsets. In this review, we discuss the changes in T helper (Th)1, Th2, Th17, Th9, Th22, regulatory T cell, T follicular helper, and T peripheral helper cells and their related factors in AIH and discuss the therapeutic potential of targeting CD4+ T-cell subsets in AIH.

Cytokine Kinetics during Progression of COVID-19 in Rwanda Patients: Could IL-9/IFNγ Ratio Predict Disease Severity?

For effective treatments and preventive measures against severe COVID-19, it is essential to determine early markers of disease severity in different populations. We analysed the cytokine kinetics of 129 COVID-19 patients with mild symptoms, 68 severe cases, and 20 healthy controls for the first time in Rwanda. Pro-inflammatory (IFNγ, IL-6, TNFα), Treg (IL-10, TGFβ1, TGFβ3), Th9 (IL-9), Th17 (IL-17), and Th2 (IL-4, IL-13) cytokines, total IgM and IgG, as well as gene expressions of FoxP3, STAT5+, IFNγ-R1, and ROR alpha+, were measured at day 1, day 7, day 14, day 21, and day 28 post-infection. Severe cases showed a significantly stronger increase than mild patients in levels of all cytokines (except IL-9) and all gene expression on day 1 of infection. Some cytokine levels dropped to levels comparable to mild cases at later time points. Further analysis identified IFNγ as a marker of severity throughout the disease course, while TGFβ1, IL-6, and IL-17 were markers of severity only at an early phase. Importantly, this study revealed a striking low IL-9 level and high IFNγ/IL-9 ratio in the plasma of patients who later died compared to mild and severe cases who recovered, suggesting that this could be an important biomarker for predicting the severity of COVID-19 and post-COVID-19 syndrome.

Counteracting Immunosenescence-Which Therapeutic Strategies Are Promising?

Aging attenuates the overall responsiveness of the immune system to eradicate pathogens. The increased production of pro-inflammatory cytokines by innate immune cells under basal conditions, termed inflammaging, contributes to impaired innate immune responsiveness towards pathogen-mediated stimulation and limits antigen-presenting activity. Adaptive immune responses are attenuated as well due to lowered numbers of naïve lymphocytes and their impaired responsiveness towards antigen-specific stimulation. Additionally, the numbers of immunoregulatory cell types, comprising regulatory T cells and myeloid-derived suppressor cells, that inhibit the activity of innate and adaptive immune cells are elevated. This review aims to summarize our knowledge on the cellular and molecular causes of immunosenescence while also taking into account senescence effects that constitute immune evasion mechanisms in the case of chronic viral infections and cancer. For tumor therapy numerous nanoformulated drugs have been developed to overcome poor solubility of compounds and to enable cell-directed delivery in order to restore immune functions, e.g., by addressing dysregulated signaling pathways. Further, nanovaccines which efficiently address antigen-presenting cells to mount sustained anti-tumor immune responses have been clinically evaluated. Further, senolytics that selectively deplete senescent cells are being tested in a number of clinical trials. Here we discuss the potential use of such drugs to improve anti-aging therapy.

Transcriptional control of ILC identity

Innate lymphoid cells (ILCs) are heterogeneous innate immune cells which participate in host defense, mucosal repair and immunopathology by producing effector cytokines similarly to their adaptive immune cell counterparts. The development of ILC1, 2, and 3 subsets is controlled by core transcription factors: T-bet, GATA3, and RORγt, respectively. ILCs can undergo plasticity and transdifferentiate to other ILC subsets in response to invading pathogens and changes in local tissue environment. Accumulating evidence suggests that the plasticity and the maintenance of ILC identity is controlled by a balance between these and additional transcription factors such as STATs, Batf, Ikaros, Runx3, c-Maf, Bcl11b, and Zbtb46, activated in response to lineage-guiding cytokines. However, how interplay between these transcription factors leads to ILC plasticity and the maintenance of ILC identity remains hypothetical. In this review, we discuss recent advances in understanding transcriptional regulation of ILCs in homeostatic and inflammatory conditions.

Roles of Pyroptosis-Related Genes in the Diagnosis and Subtype Classification of Periodontitis

Pyroptosis is widely involved in many diseases, including periodontitis. Nonetheless, the functions of pyroptosis-related genes (PRGs) in periodontitis are still not fully elucidated. Therefore, we aimed to investigate the role of PRGs in periodontitis. Three datasets (GSE10334, GSE16134, and GSE173078) from the Gene Expression Omnibus (GEO) were selected to analyze the differences in expression values of the PRGs between nonperiodontitis and periodontitis tissue samples using difference analysis. Following this, five hub PRGs (charged multivesicular body protein 2B, granzyme B, Z-DNA-binding protein 1, interleukin-1β, and interferon regulatory factor 1) predicting periodontitis susceptibility were screened by establishing a random forest model, and a predictive nomogram model was constructed on the basis of these genes. Decision curve analysis suggested that the PRG-based predictive nomogram model could provide clinical benefits to patients. Three distinct PRG patterns (cluster A, cluster B, and cluster C) in the periodontitis samples were revealed according to the 48 significant PRGs, and the difference in the immune cell infiltration among the three patterns was explored. We observed that all infiltrating immune cells, except type 2 T helper cells, differ significantly among the three patterns. To quantify the PRG patterns, the PRG score was calculated by principal component analysis. According to the results, cluster B had the highest PRG score, followed by cluster A and cluster C. In conclusion, PRGs significantly contribute to the development of periodontitis. Our study of PRG patterns might open up a new avenue to guide individualized treatment plans for patients with periodontitis.

MiR-493-5p inhibits Th9 cell differentiation in allergic asthma by targeting FOXO1

The role of micro RNAs (miRNAs) in asthma remains unclear. In this study, we examined the role of miRNA in targeting FOXO1 in asthma. Results showed that miR-493-5p was one of the differentially expressed miRNAs in the PBMCs of asthmatic children, and was also associated with Th cell differentiation. The miR-493-5p expression decreased significantly in the OVA-induced asthma mice than the control groups. The miR-493-5p mimic inhibited the expression of the IL-9, IRF4 and FOXO1, while the inhibitor restored these effects. Moreover, the Dual-Luciferase analysis results showed FOXO1 as a novel valid target of miR-493-5p. According to the rescue experiment, miR-493-5p inhibited Th9 cell differentiation by targeting FOXO1. Then the exosomes in association with the pathogenesis of asthma was identified. Various inflammatory cells implicated in asthmatic processes including B and T lymphocytes, DCs, mast cells, and epithelial cells can release exosomes. Our results demonstrated that the DC-derived exosomes can inhibit Th9 cell differentiation through miR-493-5p, thus DC-derived exosomal miR-493-5p/FOXO1/Th9 may serve as a potential therapeutic target in the development of asthma.

The Roles of Skin Langerhans Cells in Immune Tolerance and Cancer Immunity

Langerhans cells (LC) are a unique population of tissue-resident macrophages with dendritic cell (DC) functionality that form a network of cells across the epidermis of the skin. Their location at the skin barrier suggests an important role for LC as immune sentinels at the skin surface. The classification of LC as DC over the past few decades has driven the scientific community to extensively study how LC function as DC-like cells that prime T cell immunity. However, LC are a unique type of tissue-resident macrophages, and recent evidence also supports an immunoregulatory role of LC at steady state and during specific inflammatory conditions, highlighting the impact of cutaneous environment in shaping LC functionality. In this mini review, we discuss the recent literature on the immune tolerance function of LC in homeostasis and disease conditions, including malignant transformation and progression; as well as LC functional plasticity for adaption to microenvironmental cues and the potential connection between LC population heterogeneity and functional diversity. Future investigation into the molecular mechanisms that LC use to integrate different microenvironment cues and adapt immunological responses for controlling LC functional plasticity is needed for future breakthroughs in tumor immunology, vaccine development, and treatments for inflammatory skin diseases.

Promoter Binding and Nuclear Retention Features of Zebrafish IRF Family Members in IFN Response

Interferon regulatory factors (IRFs) constitute a family of transcription factors that synchronize interferon (IFN) antiviral response through translocating to nucleus and binding to the promoters of IFN and IFN-stimulated genes (ISGs). Fish contain 11 IRF members; however, whether or how fish IRF family genes function in IFN response remains limited. Herein, we determine the regulatory roles of 11 zebrafish IRF family members in IFN response relevant to their subcellular localization and promoter binding. Zebrafish IRF family members display three patterns of constitutive localization, only in nucleus (IRF1/2/9/11), only in cytoplasm (IRF3/5/7), and largely in nucleus with small amounts in cytoplasm (IRF4b/6/8/10). DNA pull-down assays confirm that all zebrafish IRF proteins are capable to bind fish IFN promoters, albeit to various degrees, thus regulating IFN gene transcription as activators (IRF1/3/5/6/7/8/9/11) or repressors (IRF2/4b/10). Further characterization of distinct IFN gene activation reveals that IRF1/3/5/6/7/8/9/11 efficiently stimulate zebrafish IFNφ1 expression, and IRF1/7/11 are responsible for zebrafish IFNφ3 expression. Two conserved basic residues within the helix α3 of DNA binding domains (DBDs) contribute to constitutive or inducible nuclear import for all zebrafish IRF family members and DNA binding for most members, thereby enabling them to function as transcription factors. Our results reveal a conserved and general mechanism that specifies zebrafish IRF family proteins to nuclear import and DNA binding, thereby regulating fish IFN response.

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.

IRF1 regulates the progression of colorectal cancer via interferon‑induced proteins

Radiation is one of the main methods for the treatment of colorectal cancer (CRC) before or after surgery. However, radiotherapy tolerance of patients with CRC is often a major concern. Interferon regulatory factor 1 (IRF1) is a member of the IRF family and is involved in the development of multiple diseases, including tumors. The present study investigated the role of IRF1 in the development and radiation sensitivity of CRC. Immunohistochemistry was performed to examine the expression levels of IRF1 in tissue samples from patients with CRC, as well as in nude mice. MTT, 5‑ethynyl‑20‑deoxyuridine, colony formation, cell cycle alteration and apoptosis assays were performed in CRC cell lines. Western blotting and immunofluorescence were used to detect the expression levels of a series of proteins. RNA sequencing was applied to identify genes whose expression was upregulated by IRF1 overexpression. Xenograft nude mouse models and hematoxylin and eosin staining were used to validate the present findings in vivo. It was revealed that the expression levels of IRF1 were significantly lower in CRC tissues than in adjacent tissues. IRF1 upregulation inhibited cell proliferation and colony formation, caused G1 cell arrest, promoted cell apoptosis, and enhanced the sensitivity of CRC cells to X‑ray irradiation. The role of IRF1 in promoting the radiosensitivity of CRC was further demonstrated in nude mice with CRC xenografts. In addition, RNA sequencing revealed that overexpression of IRF1 in CRC cells significantly increased the expression levels of interferon‑induced protein family members interferon α inducible protein 6, interferon induced transmembrane protein 1 and interferon induced protein 35 (fold change >2.0). In summary, the present study demonstrated that the upregulation of IRF1 inhibited the progression and promoted the radiosensitivity of CRC, likely by regulating interferon‑induced proteins.

Dynamic Roles for IL-2-STAT5 Signaling in Effector and Regulatory CD4+ T Cell Populations

CD4⁺ Th cells are responsible for orchestrating diverse, pathogen-specific immune responses through their differentiation into a number of subsets, including T_H1, T_H2, T_H9, T follicular helper, T follicular regulatory, and regulatory T cells. The differentiation of each subset is guided by distinct regulatory requirements, including those derived from extracellular cytokine signals. IL-2 has emerged as a critical immunomodulatory cytokine that both positively and negatively affects the differentiation of individual Th cell subsets. IL-2 signals are propagated, in part, via activation of STAT5, which functions as a key regulator of CD4⁺ T cell gene programs. In this review, we discuss current understanding of the mechanisms that allow IL-2-STAT5 signaling to exert divergent effects across CD4⁺ T cell subsets and highlight specific roles for this pathway in the regulation of individual Th cell differentiation programs.

Tolerogenic and immunogenic states of Langerhans cells are orchestrated by epidermal signals acting on a core maturation gene module

Langerhans cells (LCs), residing in the epidermis, are able to induce potent immunogenic responses and also to mediate immune tolerance. We propose that tolerogenic and immunogenic responses of LCs are directed by signaling from the epidermis and involve counter-acting gene circuits that are coupled to a core maturation gene module. We base our analysis on recent genetic and genomic findings facilitating the understanding of the molecular mechanisms controlling these divergent immune functions. Comparing gene regulatory network (GRN) analyses of various types of dendritic cells (DCs) including LCs we integrate signaling-dependent (TGFβ, EpCAM, β-Catenin) and transcription factor (IRF4, IRF1, NFκB) regulated gene circuits that appear to orchestrate the distinctive LC functional states. Our model proposes, that while epidermal signaling in the steady-state promotes LC tolerogenic function, the disruption of cell-cell contacts coupled with inflammatory signaling induces LC immunogenic programing. The conceptual framework emphasizes the sensing of discrete epidermal and inflammatory cues by resident LCs in dictating their genomic programing and cell state dynamics.

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.

Microenvironmental Th9 and Th17 lymphocytes induce metastatic spreading in lung cancer

Immune microenvironment plays a critical role in lung cancer control versus progression and metastasis. In this investigation, we explored the effect of tumor-infiltrating lymphocyte subpopulations on lung cancer biology by studying in vitro cocultures, in vivo mouse models, and human lung cancer tissue. Lymphocyte conditioned media (CM) induced epithelial-mesenchymal transition (EMT) and migration in both primary human lung cancer cells and cell lines. Correspondingly, major accumulation of Th9 and Th17 cells was detected in human lung cancer tissue and correlated with poor survival. Coculturing lung cancer cells with Th9/Th17 cells or exposing them to the respective CM induced EMT in cancer cells and modulated the expression profile of genes implicated in EMT and metastasis. These features were reproduced by the signatory cytokines IL-9 and IL-17, with gene regulatory profiles evoked by these cytokines partly overlapping and partly complementary. Coinjection of Th9/Th17 cells with tumor cells in WT, Rag1-/-, Il9r-/-, and Il17ra-/- mice altered tumor growth and metastasis. Accordingly, inhibition of IL-9 or IL-17 cytokines by neutralizing antibodies decreased EMT and slowed lung cancer progression and metastasis. In conclusion, Th9 and Th17 lymphocytes induce lung cancer cell EMT, thereby promoting migration and metastatic spreading and offering potentially novel therapeutic strategies.

Dexmedetomidine-up-regulated microRNA-381 exerts anti-inflammatory effects in rats with cerebral ischaemic injury via the transcriptional factor IRF4

Dexmedetomidine (Dex) possesses analgesic and anaesthetic values and reported being used in cerebral ischaemic injury therapeutics. Accumulating studies have determined the effect of microRNAs (miRNAs) on the cerebral ischaemic injury. Thus, the present study aimed to unravel the molecular mechanism of miR-381 and Dex in cerebral ischaemic injury. For this purpose, the cerebral ischaemic injury rat model was established by induction of middle cerebral artery occlusion (MCAO) and expression of miR-381 and IRF4 was determined. Thereafter, MCAO rats were treated with Dex, miR-381 mimic, miR-381 inhibitor and oe-IRF4 respectively, followed by evaluation of neurological function. Furthermore, neuron cells were isolated from the hippocampus of rats and subjected to oxygen-glucose deprivation (OGD). Then, OGD-treated neuron cells and primary neuron cells were examined by gain- and loss-of-function assay. Neuron cell apoptosis was detected using TUNEL staining and flow cytometry. The correlation between interferon regulatory factor 4 (IRF4) and interleukin (IL)-9 was detected. Our results showed down-regulated miR-38 and up-regulated IRF4 in MCAO rats. Besides, IRF4 was targeted by miR-381 in neuron cells. Dex and overexpressed miR-381, or silenced IRF4 improved the neurological function and inhibited neuron cell apoptosis in MCAO rats. Additionally, in MCAO rats, Dex was found to increase the miR-381 expression and reduced IRF4 expression to decrease the IL-9 expression, which suppressed the inflammatory response and cell apoptosis both in vivo and in vitro. Importantly, our study demonstrated that Dex elevated the expression of miR-381, which ultimately results in the inhibition of inflammation response in rats with cerebral ischaemic injury.

Interferon regulatory factor 4 deficiency in CD8+ T cells abrogates terminal effector differentiation and promotes transplant acceptance

Allogeneic CD8⁺ cytotoxic T cells play an essential role in rejecting transplanted allografts, but how their effector function is regulated on a transcriptional level remains unclear. Herein, we investigate the role of interferon regulatory factor 4 (IRF4) in controlling CD8⁺ T-cell function in response to transplant. B6.Rag1^-/- mice were adoptively transferred with CD8⁺ T cells isolated from either Irf4^fl/fl Cd4-Cre (T-cell-specific Irf4-deficient) or Irf4^fl/fl control mice, followed by BALB/c skin transplantation. Recipients that received Irf4-deficient CD8⁺ T cells permanently accepted the skin allografts, whereas recipients that received control CD8⁺ T cells acutely rejected the transplanted skins. Mechanistically, compared with the transferred control CD8⁺ T cells in B6.Rag1^-/- recipients, the transferred Irf4-deficient CD8⁺ T cells lost the capacity to differentiate into CD127^- KLRG1⁺ terminal effector cells, barely produced effector cytokines and cytotoxic molecules (e.g. IL-2, IFN-γ, TNF-α, granzyme A and granzyme B), and displayed defect in proliferative capacity, evident by their decreased Ki67 expression and lower frequencies. Moreover, the transferred Irf4-deficient CD8⁺ T cells displayed low expression of transcription factors ID2 and T-bet that govern the terminal effector T-cell programmes, and high expression of transcription factor TCF1 that maintains the naïve-memory T-cell programmes. Hence, IRF4 deficiency in CD8⁺ T cells abrogates their terminal effector differentiation and promotes transplant acceptance. These findings suggest that targeting IRF4 expression represents an attractive and promising therapeutic approach for inducing transplant acceptance.

BATF3 is sufficient for the induction of Il9 expression and can compensate for BATF during Th9 cell differentiation

Th9 cells preferentially produce IL-9 and participate in allergic responses and asthma. Differentiation of Th9 cells is induced by IL-4 and TGF-β, and then the cells are amplified by OX40 signals. The transcription factors PU.1, IRF4, and BATF are required for Th9 differentiation. BATF3 is an AP-1 family transcription factor that is highly homologous to BATF; however, its role in Th9 cells is poorly defined. Here, we show that OX40 signaling induced the expression of Batf3 and that its overexpression in the presence or absence of OX40 signaling increased the expression of IL-9 in Th9 cells. BATF3 physically interacted with IRF4 and was bound to the Il9 locus. A transient reporter assay revealed that the BATF3–IRF4 complex induced Il9 promoter activity. BATF3 rescued Il9 expression and restored the capacity to induce the airway inflammation in Batf KO Th9 cells. Thus, BATF3 itself is sufficient for the induction of Th9 cell differentiation and can substitute for BATF during Th9 cell differentiation.

A protein that regulates gene expression in immune cells may contribute to airway inflammation in asthma and allergies. A subset of immune cells known as Th9 cells plays a prominent role in these respiratory disorders, and researchers led by Gap Ryol Lee at Sogang University in Seoul, South Korea, set out to characterize signaling mechanisms that promote Th9 production. They focused specifically on a protein called BATF3, which regulates genes responsible for maturation of a variety of other immune cell types, but whose role with regard to Th9 is poorly understood. They determined that BATF3 has a potent effect in terms of inducing Th9 cell activity, and can even take the place of another known Th9-inducing protein. These findings could assist in the development of treatments that keep airway-constricting inflammation in check.

The γc Family of Cytokines: Basic Biology to Therapeutic Ramifications

The common cytokine receptor γ chain, γ_c, is a component of the receptors for interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21. Mutation of the gene encoding γ_c results in X-linked severe combined immunodeficiency in humans, and γ_c family cytokines collectively regulate development, proliferation, survival, and differentiation of immune cells. Here, we review the basic biology of these cytokines, highlighting mechanisms of signaling and gene regulation that have provided insights for immunodeficiency, autoimmunity, allergic diseases, and cancer. Moreover, we discuss how studies of this family stimulated the development of JAK3 inhibitors and present an overview of current strategies targeting these pathways in the clinic, including novel antibodies, antagonists, and partial agonists. The diverse roles of these cytokines on a range of immune cells have important therapeutic implications.

An improved genome assembly for Larimichthys crocea reveals hepcidin gene expansion with diversified regulation and function

Larimichthys crocea (large yellow croaker) is a type of perciform fish well known for its peculiar physiological properties and economic value. Here, we constructed an improved version of the L. crocea genome assembly, which contained 26,100 protein-coding genes. Twenty-four pseudo-chromosomes of L. crocea were also reconstructed, comprising 90% of the genome assembly. This improved assembly revealed several expansions in gene families associated with olfactory detection, detoxification, and innate immunity. Specifically, six hepcidin genes (LcHamps) were identified in L. crocea, possibly resulting from lineage-specific gene duplication. All LcHamps possessed similar genomic structures and functional domains, but varied substantially with respect to expression pattern, transcriptional regulation, and biological function. LcHamp1 was associated specifically with iron metabolism, while LcHamp2s were functionally diverse, involving in antibacterial activity, antiviral activity, and regulation of intracellular iron metabolism. This functional diversity among gene copies may have allowed L. crocea to adapt to diverse environmental conditions.

Chronic rhinosinusitis: pathogenesis, therapy options, and more

INTRODUCTION

When rhinosinusitis - the inflammation of the nasal cavity and paranasal sinuses - persists for over 12 weeks, it is termed 'chronic rhinosinusitis' (CRS). Both innate and adaptive immunity contribute to the heterogeneous inflammatory pathogenesis of CRS, which is driven by genetic and environmental factors and the microbiome. CRS is classified by the presence of polyps. Molecular mechanisms in CRS with nasal polyps are similar to those in atopic diseases.

AREAS COVERED

This review focuses on the immune pathogenesis of CRS, differences between the two CRS subtypes, and latest treatments that may aid in the provision of personalized medicine.

EXPERT OPINION

Basic research in the last decade has helped significantly in enhancing our knowledge of the pathophysiologic processes of CRS, due to which there is now a better understanding of the associated natural history, physiopathology, novel treatments, and prevention strategies. Treatment success depends on the clarification of the underlying pathogenesis and disease-contributing factors. The exploration of disease endotypes and introduction of novel agents are important advancements. Prior studies performed without disease-endotyping resulted in the inefficiency of certain drugs and insignificant results. The identification of biomarkers, development of personalized approaches, and utilization of disease algorithms are required for CRS therapy success.

A hyperactive mutant of interferon-regulatory factor 4

We found that deletion of the final 30 amino acids of transcription factor IRF4's (interferon-regulatory factor) C-terminus creates hyperactive IRF4. When introduced into IRF4-deficient CD4⁺ or CD8⁺ T cells, more type 17 differentiation was found compared to WT IRF4. Interestingly, Th9 differentiation and Th2-linked IL-13 production were much less altered.

Role of Th9 cells and IL-9 in inflammatory bowel disease

Th9 cells, a novel subset of CD4⁺ T cells, mainly produce IL-9 and have a critical role in allergic disease, autoimmune disease, and tumors. IL-9 can promote inflammation by increasing the number of inflammatory cells and the secretion of inflammatory mediators and thus play an important role in the development of inflammatory bowel disease (IBD). Th9 cells and IL-9 aggravate inflammation of the colon in both experimental models of colitis and in patients with IBD. The blockade of IL-9 is suited to significantly ameliorate the disease activity and severity of IBD.

Frequent interferon regulatory factor 1 (IRF1) binding at remote elements without histone modification

Transcriptional activators bind DNA and recruit cofactors to modify chromatin. The extent to which these two events are separable is unclear. Here, using a custom ChIP tiling array to map chromatin modifications, we show that interferon-γ-induced DNA binding of signal transducer and activator of transcription 1 (STAT1), typically associated with the transcription factor interferon regulatory factor 1 (IRF1), causes histone acetylation (H3ac, H4ac). In contrast, among IRF1 sites lacking concomitant STAT1 recruitment, only 25% underwent inducible histone acetylation, 31% exhibited constitutive histone acetylation, and 44% had no histone acetylation. These latter "orphan sites" also lacked other activating modifications (e.g. H3K4me1, H3K4me2) and were typically remote from transcription start sites. In these cases the closest gene was typically an IFNγ-inducible locus that did not respond to IFNγ in this setting. Orphan sites were detected in different cell types, suggesting broad relevance. Despite an atypical downstream response (i.e. no histone modifications), IRF1 binding depended on SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4 (SMARCA4 or BRG1), as is typical of active IRF1 enhancers. Although SMARCA4 permitted IRF1 access to the orphan sites, there was no corecruitment of the histone acetyltransferases CREB-binding protein (CBP) and p300. Orphan sites were constitutively unacetylated, and several were marked with repressive chromatin modifications (e.g. H3K27me3). In conclusion, although IRF1 can trigger enhanceosome formation independently of STAT1, its ability to do so depends on local chromatin cues.

Transcriptional Control of Th9 Cells: Role of Foxo1 in Interleukin-9 Induction

Interleukin (IL) 9-producing helper T (Th) 9 cells play a major role in contributing immunity against extracellular pathogens. In addition, the role of Th9 cells was demonstrated in the pathogenesis of allergic, skin, and intestinal inflammation. The functions of Th9 cells were further extended in antitumor immune response, as Th9 cells were suggested to be potent antitumor Th cells. Given the pleotropic functions of IL-9 in various pathophysiological conditions, it is essential to understand the differentiation and stability of Th9 cells and other IL-9-producing T cells. In addition to Th9 cells, Th2 and Th17 cells as well as induced Foxp3+ regulatory T cells (iTregs) cells also produce IL-9, but how IL-9 production is regulated in these cell types is not yet clearly defined. Although Th2, Th9 and Th17 cells as well as iTregs develop in the presence of distinct differentiating factors, yet they all express IL-9 together with their own lineage specific cytokines. Here, in this review, we summarize the current understanding of signaling pathways that lead to the promotion of differentiation of Th9 cells and IL-9 induction in Th2 and Th17 cells, as well as in iTregs. We further discuss the transcriptional regulation of Th9 cells in context of Foxo1, as an essential transcription factor required for the development and functions of Th9 and other IL-9-producing T cells.

CD96 expression determines the inflammatory potential of IL-9-producing Th9 cells

T helper type (Th) 9 cells demonstrate both pro- and antiinflammatory properties, pointing to a functional heterogeneity not examined so far. Applying single cell gene expression analysis of alloreactive Th9 cells, we revealed the existence of two major subsets, CD96^high and CD96^low Th9 cells, with strongly opposing inflammatory and, especially, colitis-inducing potential. Mechanistically, we found that CD96 controls cytokine and colitis-inducing potential of Th9 cells, providing strong evidence for an inhibitory role of CD96 in controlling CD4⁺ T-cell effector functions. Thus, interfering with CD96-mediated immune inhibition would be a promising approach in preventing Th9-mediated diseases, such as ulcerative colitis, or reinforcement of Th9-mediated immune control of tumors and infections.

Recent findings demonstrated proinflammatory functions of interleukin (IL)-9–producing T helper type (Th) 9 cells in the pathogenesis of intestinal bowel diseases (IBDs). However, also antiinflammatory properties have been ascribed to Th9 cells, pointing to a functional heterogeneity. To dissect the specific expression pattern and, especially, diversity of murine antigen-specific Th9 cells, we applied single cell transcription profiling. Th9 cells displayed reduced expression of typical activation markers, such as Cd40 ligand and Cd96, whereas expression of Cd25 and Cd83 was increased compared with other Th subsets. Importantly, we identified two subsets of Th9 cells differing above all in their CD96 expression. The heterogeneous CD96 expression was specific for Th9 cells and not observed for other Th subtypes, such as Th1 cells. Lower CD96 expression was also observed in human IL-9⁺ compared with IFN-γ⁺ T cells. Although Il9 was highly transcribed by all Th9 cells, IL-9 mRNA and protein expression was increased in CD96^low cells. Transfer of CD96^low Th9 cells into recombination activating gene 1-deficient (Rag1^−/−) mice caused severe weight loss, intestinal and colonic inflammation, and destruction of allogeneic skin grafts and thus showed high inflammatory potential. This was associated with their expansion and tissue accumulation. Contrastingly, CD96^high Th9 cells did not cause colitis and showed reduced expansion and migratory potential. Blockade of CD96 completely restored the expansion and inflammatory properties of CD96^high Th9 cells. Collectively, our data suggest an inhibitory role for the cosignaling receptor CD96 in Th9 cells, raising new opportunities in the treatment of IL-9–associated inflammations such as IBD.

IRF-1 SNPs influence the risk for childhood allergic asthma: A critical role for pro-inflammatory immune regulation

BACKGROUND

Allergic and non-allergic childhood asthma has been characterized by distinct immune mechanisms. While interferon regulating factor 1 (IRF-1) polymorphisms (SNPs) influence atopy risk, the effect of SNPs on asthma phenotype-specific immune mechanisms is unclear. We assessed whether IRF-1 SNPs modify distinct immune-regulatory pathways in allergic and non-allergic childhood asthma (AA/NA).

METHODS

In the CLARA study, asthma was characterized by doctor's diagnosis and AA vs NA by positive or negative specific IgE. Children were genotyped for four tagging SNPs within IRF-1 (n = 172). mRNA expression was measured with qRT-PCR. Gene expression was analyzed depending on genetic variants within IRF-1 and phenotype including haplotype estimation and an allelic risk score.

RESULTS

Carrying the risk alleles of IRF-1 in rs10035166, rs2706384, or rs2070721 was associated with increased risk for AA. Carrying the non-risk allele in rs17622656 was associated with lower risk for AA but not NA. In AA carrying the risk alleles, an increased pro-inflammatory expression of ICAM3, IRF-8, XBP-1, IFN-γ, RGS13, RORC, and TSC2 was observed. NOD2 expression was decreased in AA with risk alleles in rs2706384 and rs10035166 and with risk haplotype. Further, AA with risk haplotype showed increased IL-13 secretion. NA with risk allele in rs2070721 compared to non-risk allele in rs17622656 showed significantly upregulated calcium, innate, mTOR, neutrophil, and inflammatory-associated genes.

CONCLUSION

IRF-1 polymorphisms influence the risk for childhood allergic asthma being associated with increased pro-inflammatory gene regulation. Thus, it is critical to implement IRF-1 genetics in immune assessment for childhood asthma phenotypes.