木内 政宏

PURPOSE: Auto-antibodies (auto-abs) to type I interferons (IFNs) have been identified in patients with life-threatening coronavirus disease 2019 (COVID-19), suggesting that the presence of auto-abs may be a risk factor for disease severity. We therefore investigated the mechanism underlying COVID-19 exacerbation induced by auto-abs to type I IFNs. METHODS: We evaluated plasma from 123 patients with COVID-19 to measure auto-abs to type I IFNs. We performed single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells from the patients with auto-abs and conducted epitope mapping of the auto-abs. RESULTS: Three of 19 severe and 4 of 42 critical COVID-19 patients had neutralizing auto-abs to type I IFNs. Patients with auto-abs to type I IFNs showed no characteristic clinical features. scRNA-seq from 38 patients with COVID-19 revealed that IFN signaling in conventional dendritic cells and canonical monocytes was attenuated, and SARS-CoV-2-specific BCR repertoires were decreased in patients with auto-abs. Furthermore, auto-abs to IFN-α2 from COVID-19 patients with auto-abs recognized characteristic epitopes of IFN-α2, which binds to the receptor. CONCLUSION: Auto-abs to type I IFN found in COVID-19 patients inhibited IFN signaling in dendritic cells and monocytes by blocking the binding of type I IFN to its receptor. The failure to properly induce production of an antibody to SARS-CoV-2 may be a causative factor of COVID-19 severity.

OBJECTIVES: IgG4-related disease (IgG4-RD) is a systemic autoimmune disease with an unknown etiology, affecting single/multiple organ(s). Pathological findings include the infiltration of IgG4-producing plasma cells, obliterative phlebitis, and storiform fibrosis. Although immunological studies have shed light on the dysregulation of lymphocytes in IgG4-RD pathogenesis, the role of non-immune cells remains unclear. This study aimed to investigate the demographics and characteristics of non-immune cells in IgG4-RD and explore potential biomarkers derived from non-immune cells in the sera. METHODS: We conducted single-cell RNA sequence (scRNA-seq) on non-immune cells isolated from submandibular glands of IgG4-RD patients. We focused on fibroblasts expressing collagen type XV and confirmed the presence of those fibroblasts using immunohistochemistry. Additionally, we measured the levels of collagen type XV in the sera of IgG4-RD patients. RESULTS: The scRNA-seq analysis revealed several distinct clusters consisting of fibroblasts, endothelial cells, ductal cells, and muscle cells. Differential gene expression analysis showed upregulation of COL15A1 in IgG4-RD fibroblasts compared to control subjects. Notably, COL15A1-positive fibroblasts exhibited a distinct transcriptome compared to COL15A1-negative counterparts. Immunohistochemical analysis confirmed a significant presence of collagen type XV-positive fibroblasts in IgG4-RD patients. Furthermore, immune-suppressive therapy in active IgG4-RD patients resulted in decreased serum levels of collagen type XV. CONCLUSIONS: Our findings suggest that collagen type XV-producing fibroblasts may represent a disease-characterizing non-immune cell population in IgG4-RD and hold potential as a disease-monitoring marker.

Uncontrolled type 2 immunity by type 2 helper T (Th2) cells causes intractable allergic diseases; however, whether the interaction of CD4+ T cells shapes the pathophysiology of allergic diseases remains unclear. We identified a subset of Th2 cells that produced the serine proteases granzyme A and B early in differentiation. Granzymes cleave protease-activated receptor (Par)-1 and induce phosphorylation of p38 mitogen-activated protein kinase (MAPK), resulting in the enhanced production of IL-5 and IL-13 in both mouse and human Th2 cells. Ubiquitin-specific protease 7 (USP7) regulates IL-4-induced phosphorylation of STAT3, resulting in granzyme production during Th2 cell differentiation. Genetic deletion of Usp7 or Gzma and pharmacological blockade of granzyme B ameliorated allergic airway inflammation. Furthermore, PAR-1+ and granzyme+ Th2 cells were colocalized in nasal polyps from patients with eosinophilic chronic rhinosinusitis. Thus, the USP7-STAT3-granzymes-Par-1 pathway is a potential therapeutic target for intractable allergic diseases.

Tumor-specific CD8+ T cells play a pivotal role in anti-tumor immunity and are a key target of immunotherapeutic approaches. Intratumoral CD8+ T cells are heterogeneous; Tcf1+ stem-like CD8+ T cells give rise to their cytotoxic progeny - Tim-3+ terminally differentiated CD8+ T cells. However, where and how this differentiation process occurs has not been elucidated. We herein show that terminally differentiated CD8+ T cells can be generated within tumor-draining lymph nodes (TDLNs) and that CD69 expression on tumor-specific CD8+ T cells controls its differentiation process through regulating the expression of the transcription factor TOX. In TDLNs, CD69 deficiency diminished TOX expression in tumor-specific CD8+ T cells, and consequently promoted generation of functional terminally differentiated CD8+ T cells. Anti-CD69 administration promoted the generation of terminally differentiated CD8+ T cells, and the combined use of anti-CD69 and anti-PD-1 showed an efficient anti-tumor effect. Thus, CD69 is an attractive target for cancer immunotherapy that synergizes with immune checkpoint blockade.

CD4+ memory T cells are central to long-lasting protective immunity and are involved in shaping the pathophysiology of chronic inflammation. While metabolic reprogramming is critical for the generation of memory T cells, the mechanisms controlling the redox metabolism in memory T cell formation remain unclear. We found that reactive oxygen species (ROS) metabolism changed dramatically in T helper-2 (Th2) cells during the contraction phase in the process of memory T cell formation. Thioredoxin-interacting protein (Txnip), a regulator of oxidoreductase, regulated apoptosis by scavenging ROS via the nuclear factor erythroid 2-related factor 2 (Nrf2)-biliverdin reductase B (Blvrb) pathway. Txnip regulated the pathology of chronic airway inflammation in the lung by controlling the generation of allergen-specific pathogenic memory Th2 cells in vivo. Thus, the Txnip-Nrf2-Blvrb axis directs ROS metabolic reprogramming in Th2 cells and is a potential therapeutic target for intractable chronic inflammatory diseases.

Allergic conjunctivitis is a chronic inflammatory disease that is characterized by severe itch in the conjunctiva, but how neuro-immune interactions shape the pathogenesis of severe itch remains unclear. We identified a subset of memory-type pathogenic Th2 cells that preferentially expressed Il1rl1-encoding ST2 and Calca-encoding calcitonin-gene-related peptide (CGRP) in the inflammatory conjunctiva using a single-cell analysis. The IL-33-ST2 axis in memory Th2 cells controlled the axonal elongation of the peripheral sensory C-fiber and the induction of severe itch. Pharmacological blockade and genetic deletion of CGRP signaling in vivo attenuated scratching behavior. The analysis of giant papillae from patients with severe allergic conjunctivitis revealed ectopic lymphoid structure formation with the accumulation of IL-33-producing epithelial cells and CGRP-producing pathogenic CD4+ T cells accompanied by peripheral nerve elongation. Thus, the IL-33-ST2-CGRP axis directs severe itch with neuro-reconstruction in the inflammatory conjunctiva and is a potential therapeutic target for severe itch in allergic conjunctivitis.

The liver stores glycogen and releases glucose into the blood upon increased energy demand. Group 2 innate lymphoid cells (ILC2) in adipose and pancreatic tissues are known for their involvement in glucose homeostasis, but the metabolic contribution of liver ILC2s has not been studied in detail. Here we show that liver ILC2s are directly involved in the regulation of blood glucose levels. Mechanistically, interleukin (IL)-33 treatment induces IL-13 production in liver ILC2s, while directly suppressing gluconeogenesis in a specific Hnf4a/G6pc-high primary hepatocyte cluster via Stat3. These hepatocytes significantly interact with liver ILC2s via IL-13/IL-13 receptor signaling. The results of transcriptional complex analysis and GATA3-ChIP-seq, ATAC-seq, and scRNA-seq trajectory analyses establish a positive regulatory role for the transcription factor GATA3 in IL-13 production by liver ILC2s, while AP-1 family members are shown to suppress IL-13 release. Thus, we identify a regulatory role and molecular mechanism by which liver ILC2s contribute to glucose homeostasis.

The mortality of coronavirus disease 2019 (COVID-19) is strongly correlated with pulmonary vascular pathology accompanied by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-triggered immune dysregulation and aberrant activation of platelets. We combined histological analyses using field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy analyses of the lungs from autopsy samples and single-cell RNA sequencing of peripheral blood mononuclear cells to investigate the pathogenesis of vasculitis and immunothrombosis in COVID-19. We found that SARS-CoV-2 accumulated in the pulmonary vessels, causing exudative vasculitis accompanied by the emergence of thrombospondin-1-expressing noncanonical monocytes and the formation of myosin light chain 9 (Myl9)-containing microthrombi in the lung of COVID-19 patients with fatal disease. The amount of plasma Myl9 in COVID-19 was correlated with the clinical severity, and measuring plasma Myl9 together with other markers allowed us to predict the severity of the disease more accurately. This study provides detailed insight into the pathogenesis of vasculitis and immunothrombosis, which may lead to optimal medical treatment for COVID-19.

Type 2 helper T (Th2) cells, a subset of CD4⁺ T cells, play an important role in the host defense against pathogens and allergens by producing Th2 cytokines, such as interleukin-4 (IL-4), IL-5, and IL-13, to trigger inflammatory responses. Emerging evidence reveals that Th2 cells also contribute to the repair of injured tissues after inflammatory reactions. However, when the tissue repair process becomes chronic, excessive, or uncontrolled, pathological fibrosis is induced, leading to organ failure and death. Thus, proper control of Th2 cells is needed for complete tissue repair without the induction of fibrosis. Recently, the existence of pathogenic Th2 (Tpath2) cells has been revealed. Tpath2 cells produce large amounts of Th2 cytokines and induce type 2 inflammation when activated by antigen exposure or tissue injury. In recent studies, Tpath2 cells are suggested to play a central role in the induction of type 2 inflammation whereas the role of Tpath2 cells in tissue repair and fibrosis has been less reported in comparison to conventional Th2 cells. In this review, we discuss the roles of conventional Th2 cells and pathogenic Th2 cells in the sequence of tissue inflammation, repair, and fibrosis.

BACKGROUND: Allergic rhinitis is a growing problem worldwide. Currently, the only treatment that can modify the disease is antigen-specific immunotherapy; however, its mechanism(s) of action is not fully understood. OBJECTIVE: To comprehensively investigate the role and changes of antigen-specific T cells before and after sublingual immunotherapy (SLIT) for Japanese cedar pollinosis (JCP). METHODS: We cultured PBMCs obtained both before and at 1 year after initiating SLIT and used a combination of single-cell RNA sequence and repertoire sequencing. To investigate biomarkers, we used PBMCs from patients participating a phase II/III trial of SLIT tablets for JCP and PBMCs from good and poor responders in outpatients. RESULTS: Antigen-stimulated culturing after SLIT led to clonal expansion of Th2 and Treg cells, and most of these CD4+ T cells retained their CDR3 regions before and after treatment, indicating antigen-specific clonal responses and differentiation secondary to SLIT. However, SLIT reduced the number of clonal functional Th2 cells but increased the Trans-type Th2 cell population that expresses musculin (MSC), TGF-β, and IL-2. Trajectory analysis suggested that SLIT induced clonal differentiation of the Trans-type Th2 cells differentiated into Treg cells. Using real-time PCR, we found that the MSC levels increased in the active SLIT group and good responders after 1 year of treatment. CONCLUSION: The combination of single-cell RNA sequencing and repertoire analysis helped reveal a part of the underlying mechanism-that SLIT promotes the expression of MSC on pathogenic Th2 cells and suppresses their function; MSC may be a potential biomarker of SLIT for allergic rhinitis.

Mounting evidence suggests that nematode infection can protect against disorders of immune dysregulation. Administration of live parasites or their excretory/secretory (ES) products has shown therapeutic effects across a wide range of animal models for immune disorders, including asthma. Human clinical trials of live parasite ingestion for the treatment of immune disorders have produced promising results, yet concerns persist regarding the ingestion of pathogenic organisms and the immunogenicity of protein components. Despite extensive efforts to define the active components of ES products, no small molecules with immune regulatory activity have been identified from nematodes. Here we show that an evolutionarily conserved family of nematode pheromones called ascarosides strongly modulates the pulmonary immune response and reduces asthma severity in mice. Screening the inhibitory effects of ascarosides produced by animal-parasitic nematodes on the development of asthma in an ovalbumin (OVA) murine model, we found that administration of nanogram quantities of ascr#7 prevented the development of lung eosinophilia, goblet cell metaplasia, and airway hyperreactivity. Ascr#7 suppressed the production of IL-33 from lung epithelial cells and reduced the number of memory-type pathogenic Th2 cells and ILC2s in the lung, both key drivers of the pathology of asthma. Our findings suggest that the mammalian immune system recognizes ascarosides as an evolutionarily conserved molecular signature of parasitic nematodes. The identification of a nematode-produced small molecule underlying the well-documented immunomodulatory effects of ES products may enable the development of treatment strategies for allergic diseases.

<title>Abstract</title> CD4+ T cells not only direct immune responses against infectious micro-organisms but are also involved in the pathogenesis of inflammatory diseases. In the last two to three decades, various researchers have identified and characterized several functional CD4+ T-cell subsets, including T-helper 1 (Th1), Th2, Th9 and Th17 cells and regulatory T (Treg) cells. In this mini-review, we introduce the concept of pathogenic Th cells that induce inflammatory diseases with a model of disease induction by a population of pathogenic Th cells: the ‘pathogenic Th population disease-induction model’. We will focus on Th2 cells that induce allergic airway inflammation—pathogenic Th2 cells (Tpath2 cells)—and discuss the nature of Tpath2 cells that shape the pathology of chronic inflammatory diseases. Various Tpath2-cell subsets have been identified and their unique features are summarized in mouse and human systems. Second, we will discuss how Th cells migrate and are maintained in chronic inflammatory lesions. We propose a model known as the ‘CD69–Myl9 system’. CD69 is a cell surface molecule expressed on activated T cells and interaction with its ligand myosin light chain 9 (Myl9) is required for the induction of inflammatory diseases. Myl9 molecules in the small vessels of inflamed lungs may play a crucial role in the migration of activated T cells into inflammatory lesions. Emerging evidence may provide new insight into the pathogenesis of chronic inflammatory diseases and contribute to the development of new therapeutic strategies for intractable inflammatory disorders.

Different dynamics of gene expression are observed during cell differentiation. In T cells, genes that are turned on early or turned off and stay off have been thoroughly studied. However, genes that are initially turned off but then turned on again after stimulation has ceased have not been defined; they are obviously important, especially in the context of acute versus chronic inflammation. Using the Th1/Th2 differentiation paradigm, we found that the Cxxc1 subunit of the Trithorax complex directs transcription of genes initially down-regulated by TCR stimulation but up-regulated again in a later phase. The late up-regulation of these genes was impaired either by prolonged TCR stimulation or Cxxc1 deficiency, which led to decreased expression of Trib3 and Klf2 in Th1 and Th2 cells, respectively. Loss of Cxxc1 resulted in enhanced pathogenicity in allergic airway inflammation in vivo. Thus, Cxxc1 plays essential roles in the establishment of a proper CD4+ T cell immune system via epigenetic control of a specific set of genes.

Memory T cells are crucial for both local and systemic protection against pathogens over a long period of time. Three major subsets of memory T cells; effector memory T (T_EM) cells, central memory T (T_CM) cells, and tissue-resident memory T (T_RM) cells have been identified. The most recently identified subset, T_RM cells, is characterized by the expression of the C-type lectin CD69 and/or the integrin CD103. T_RM cells persist locally at sites of mucosal tissue, such as the lung, where they provide frontline defense against various pathogens. Importantly, however, T_RM cells are also involved in shaping the pathology of inflammatory diseases. A number of pioneering studies revealed important roles of CD8⁺ T_RM cells, particularly those in the local control of viral infection. However, the protective function and pathogenic role of CD4⁺ T_RM cells that reside within the mucosal tissue remain largely unknown. In this review, we discuss the ambivalent feature of CD4⁺ T_RM cells in the protective and pathological immune responses. We also review the transcriptional and epigenetic characteristics of CD4⁺ T_RM cells in the lung that have been elucidated by recent technical approaches. A better understanding of the function of CD4⁺ T_RM cells is crucial for the development of both effective vaccination against pathogens and new therapeutic strategies for intractable inflammatory diseases, such as inflammatory bowel diseases and chronic allergic diseases.

Eosinophils are multifunctional leukocytes, being involved in the host defense against helminth infection, tissue homeostasis and repair of injured tissue. However, eosinophils also play critical roles in shaping the pathogenesis of allergic diseases, including fibrotic responses in allergic diseases. Eosinophils consist of various granules that are a source of cytokines, chemokines, enzymes, extracellular matrix and growth factors. Recent studies have revealed that eosinophil extracellular trap cell death (EETosis) exacerbates eosinophilic inflammation by releasing the products, including Charcot-Leyden crystals (CLCs). In type 2 inflammatory diseases, memory-type pathogenic helper T (Tpath) cells are involved in shaping the pathogenesis of eosinophilic inflammation by recruiting and activating eosinophils in vivo. We herein review the molecular mechanisms underlying the development of eosinophils and the various functions of granules, including CLCs, during eosinophilic inflammation. We also discuss the double-edged roles of eosinophils in tissue repair and type 2 immune inflammation.

Oral immunotherapy (OIT) is an effective approach to controlling food allergy. Although the detailed molecular and cellular mechanisms of OIT are unknown currently, they must be understood to advance the treatment of allergic diseases in general. To elucidate the mechanisms of OIT, especially during the immunological transition from desensitization to allergy regulation, we generated a clinical OIT murine model and used it to examine immunological events of OIT. We found that in mice that completed OIT successfully, desensitized mast cells (MCs) showed functionally beneficial alterations, such as increased induction of regulatory cytokines and enhanced expansion of regulatory T cells. Importantly, these regulatory-T-cell-mediated inhibitions of allergic responses were dramatically decreased in mice lacking OIT-induced desensitized MC. Collectively, these findings show that the desensitization process modulates the activation of MCs, leading directly to enhanced induction of regulatory-T-cell expansion and promotion of clinical allergic unresponsiveness. Our results suggest that efficiently inducing regulatory MCs is a novel strategy for the treatment of allergic disease.

Background: Invariant natural killer T (iNKT) cells are known as CD1d-restricted T cells that express the invariant T-cell receptors (TCR) Vα24 and Vβ11 in humans and specifically recognize glycolipid antigens such as α-galactosylceramide (αGalCer) presented by CD1d. iNKT cells show direct cytotoxicity toward CD1d-positive tumor cells presenting glycolipid antigens and indirect cytotoxicity by activating other cytotoxic immune cells or regulating CD1d-positive immunosuppressive cells in the tumor microenvironment. Although we previously reported that αGalCer-activated NKT cells exert a potent perforin-dependent cytotoxic activity against a wide variety of human tumor cell lines, the direct recognition of CD1d-negative tumors is controversial and the mechanism is unknown. Here we clarify whether iNKT cells recognize and exhibit cytotoxicity toward leukemia cells in a CD1d-independent manner and identify the molecule that recognizes CD1d-negative leukemia cells. Methods: Purified iNKT cells were generated from peripheral blood mononuclear cells (PBMCs) of healthy adult volunteer donors. PBMCs were cultured in complete RPMI 1640 medium for 9-14 days in the presence of 100 U/mL of recombinant human IL-2 and 200 ng/mL of αGalCer. The iNKT cells were then isolated with an autoMACS Pro separator using FITC-labeled anti-Vα24 antibody (clone, C15) and anti-FITC microbeads. We evaluated the cytotoxic activity of iNKT cells toward CD1d-negative leukemia cells within four days after isolation using a CD107a assay for degranulation, cytometric bead array for cytokine production, and cytotoxicity assay in vitro and in vivo. For in vivo cytotoxicity assays, NOG mice were inoculated with 1 × 106 K562-luc cells on day 0 and with 4 × 106 human iNKT cells on day 1. Gene knock-out (KO) was performed using a CRISPR/Cas9 system. T-cell or NK receptor-KO iNKT cells were used for experiments three or four days after electroporation of the Cas9 protein and guide RNA CRISPR ribonucleoprotein complex. Patient-derived leukemia cells were obtained from PBMCs or bone marrow mononuclear cells of pre-treatment pediatric patients. All studies were approved by the institutional review board and the Animal Care and Use Committee of Chiba University. Results: We observed that iNKT cells degranulated and released Th1 cytokines when co-cultured with CD1d-negative leukemia cells (K562, HL-60, REH, and CD1d-KO U937) as well as αGalCer-loaded CD1d-positive leukemia cells (Jurkat), and showed in vitro cytotoxicity toward these CD1d-negative leukemia cells. This CD1d-independent degranulation decreased over time after isolation and was not restored with re-stimulation by αGalCer. The cytotoxicity of iNKT cells toward K562 cells was confirmed in vivo by comparsion with survival curves of K562-inoculated NOG mice given iNKT cells or PBS alone (log-rank, p= 0.016). To identify the receptors contributing to the CD1d-independent recognition and cytotoxicity against CD1d-negative leukemia cells, we first focused on costimulatory receptors, which are also known as activating NK receptors and are expressed on iNKT cells such as NKG2D, DNAM-1, 2B4, LFA-1, and CD2, and analyzed cytotoxicity after blocking these receptors with antibodies. We found that all costimulatory receptors that we assessed contributed to cytotoxicity toward CD1d-negative leukemia cells. Next, we analyzed cytotoxicity of TCR-KO iNKT cells toward CD1d-negative leukemia cells to confirm the contribution of TCR to CD1d-independent recognition. Notably, TCR-KO iNKT cells showed decreased degranulation, Th1 cytokine release, and cytotoxicity toward K562 cells more so than iNKT cells with KO of NK receptors such as LFA-1(CD11a) or CD2. To assess the clinical application potential of adoptive iNKT cell immunotherapy for leukemia treatment, we analyzed degranulation of iNKT cells using patient-derived leukemia cells. We found iNKT cells degranulation using cells from four out of five myeloid leukemia cases, but only one out of eight BCP-ALL cases (p = 0.032). Conclusion: Primary iNKT cells activated by αGalCer can recognize and show anti-tumor effects toward leukemia cells in an unrestricted manner via CD1d. The TCR also has an important role in recognizing CD1d-negative leukemia cells and multiple NK receptors assist in cytotoxicity. Adoptive iNKT cell immunotherapy may be effective in treating myeloid leukemia. Disclosures No relevant conflicts of interest to declare.

Tissue-resident memory T cells (TRM cells) are crucial mediators of adaptive immunity in nonlymphoid tissues. However, the functional heterogeneity and pathogenic roles of CD4+ TRM cells that reside within chronic inflammatory lesions remain unknown. We found that CD69hiCD103lo CD4+ TRM cells produced effector cytokines and promoted the inflammation and fibrotic responses induced by chronic exposure to Aspergillus fumigatus. Simultaneously, immunosuppressive CD69hiCD103hiFoxp3+ CD4+ regulatory T cells were induced and constrained the ability of pathogenic CD103lo TRM cells to cause fibrosis. Thus, lung tissue-resident CD4+ T cells play crucial roles in the pathology of chronic lung inflammation, and CD103 expression defines pathogenic effector and immunosuppressive tissue-resident cell subpopulations in the inflamed lung.

BACKGROUND: Natural killer T (NKT) cells express a T-cell receptor that recognizes endogenous and environmental glycolipid antigens. Several subsets of NKT cells have been identified, including IFN-γ-producing NKT1 cells, IL-4-producing NKT2 cells, and IL-17-producing NKT17 cells. However, little is known about the factors that regulate their differentiation and respective functions within the immune system. OBJECTIVE: We sought to determine whether the polycomb repressive complex 2 protein enhancer of zeste homolog 2 (Ezh2) restrains pathogenicity of NKT cells in the context of asthma-like lung disease. METHODS: Numbers of invariant natural killer T (iNKT) 1, iNKT2, and iNKT17 cells and tissue distribution, cytokine production, lymphoid tissue localization, and transcriptional profiles of iNKT cells from wild-type and Ezh2 knockout (KO) iNKT mice were determined. The contribution of NKT cells to development of spontaneous and house dust mite-induced airways pathology, including airways hyperreactivity (AHR) to methacholine, was also assessed in wild-type, Ezh2 KO, and Ezh2 KO mice lacking NKT cells. RESULTS: Ezh2 restrains development of pathogenic NKT cells, which induce spontaneous asthma-like disease in mice. Deletion of Ezh2 increased production of IL-4 and IL-13 and induced spontaneous AHR, lung inflammation, mucus production, and IgE. Increased IL-4 and IL-13 levels, AHR, lung inflammation, and IgE levels were all dependent on iNKT cells. In house dust mite-exposed animals Ezh2 KO resulted in enhanced AHR that was also dependent on iNKT cells. CONCLUSION: Ezh2 is a central regulator of iNKT pathogenicity and suppresses the ability of iNKT cells to induce asthma-like pathology.

Memory T cells provide long-lasting protective immunity, and distinct subpopulations of memory T cells drive chronic inflammatory diseases such as asthma. Asthma is a chronic allergic inflammatory disease with airway remodeling including fibrotic changes. The immunological mechanisms that induce airway fibrotic changes remain unknown. We found that interleukin-33 (IL-33) enhanced amphiregulin production by the IL-33 receptor, ST2hi memory T helper 2 (Th2) cells. Amphiregulin-epidermal growth factor receptor (EGFR)-mediated signaling directly reprogramed eosinophils to an inflammatory state with enhanced production of osteopontin, a key profibrotic immunomodulatory protein. IL-5-producing memory Th2 cells and amphiregulin-producing memory Th2 cells appeared to cooperate to establish lung fibrosis. The analysis of polyps from patients with eosinophilic chronic rhinosinusitis revealed fibrosis with accumulation of amphiregulin-producing CRTH2hiCD161hiCD45RO+CD4+ Th2 cells and osteopontin-producing eosinophils. Thus, the IL-33-amphiregulin-osteopontin axis directs fibrotic responses in eosinophilic airway inflammation and is a potential target for the treatment of fibrosis induced by chronic allergic disorders. Asthma is a chronic allergic inflammatory disease with airway remodeling including fibrotic changes. Morimoto and colleagues find that the IL-33-ST2-amphiregulin-EGRF-osteopontin axis directs fibrotic responses in chronic allergic inflammation with the involvement of airway epithelial cells, pathogenic memory Th2 cells, and inflammatory eosinophils in both mouse and human.

Posttranslational modifications of histones are well-established epigenetic modifications that play an important role in gene expression and regulation. These modifications are partly mediated by the Trithorax group (TrxG) complex, which regulates the induction or maintenance of gene transcription. We investigated the role of Menin, a component of the TrxG complex, in the acquisition and maintenance of Th2 cell identity using T cell-specific Menin-deficient mice. Our gene expression analysis revealed that Menin was involved in the maintenance of the high expression of the previously identified Th2-specific genes rather than the induction of these genes. This result suggests that Menin plays a role in the maintenance of Th2 cell identity. Menin directly bound to the Gata3 gene locus, and this Menin-Gata3 axis appeared to form a core unit of the Th2-specific gene regulatory network. Consistent with the phenotype of Menin-deficient Th2 cells observed in vitro, Menin deficiency resulted in the attenuation of effector Th2 cell-induced airway inflammation. In addition, in memory Th2 (mTh2) cells, Menin was found to play an important role in the maintenance of the expression of Th2-specific genes, including Gata3, Il4, and Il13. Consequently, Menin-deficient mTh2 cells showed an impaired ability to recruit eosinophils to the lung, resulting in the attenuation of mTh2 cell-induced airway inflammation. This study confirmed the critical role of Menin in Th2 cell-mediated immune responses.

A novel cyclovirus was identified in the intestinal contents of Taiwan squirrels (Callosciurus erythraeus thaiwanensis) collected in Kanagawa prefecture, Japan, by metagenomic analysis, and was named Taiwan squirrel cyclovirus-1 (TsCyV-1). Phylogenetic analysis showed that TsCyV-1 formed a branch separate from other representative cyclovirus strains. TsCyV-1 is considered to be a new species in the genus Cyclovirus because the criteria for demarcation of cyclovirus species is proposed as nucleotide identities &lt;80 %.

Epigenetic modifications, such as posttranslational modifications of histones, play an important role in gene expression and regulation. These modifications are in part mediated by the Trithorax group (TrxG) complex and the Polycomb group (PcG) complex, which activate and repress transcription, respectively. We herein investigate the role of Menin, a component of the TrxG complex in T helper (Th) cell differentiation and show a critical role for Menin in differentiation and maintenance of Th17 cells. Menin(-/-) T cells do not efficiently differentiate into Th17 cells, leaving Th1 and Th2 cell differentiation intact in in vitro cultures. Menin deficiency resulted in the attenuation of Th17-induced airway inflammation. In differentiating Th17 cells, Menin directly bound to the Il17a gene locus and was required for the deposition of permissive histone modifications and recruitment of the RNA polymerase II transcriptional complex. Interestingly, although Menin bound to the Rorc locus, Menin was dispensable for the induction of Rorc expression and permissive histone modifications in differentiating Th17 cells. In contrast, Menin was required to maintain expression of Rorc in differentiated Th17 cells, indicating that Menin is essential to stabilize expression of the Rorc gene. Thus, Menin orchestrates Th17 cell differentiation and function by regulating both the induction and maintenance of target gene expression.

A novel calicivirus, St-Valerien-like virus (SVV), has been identified in asymptomatic swine in Canada, Italy and the U.S.A. In this study, we characterized a new SVV strain (NUP-24/JP) detected in fecal samples of swine in Japan. The NUP-24/JP genome had 6,409 nucleotides and 2 open reading frames (ORF1 and ORF2). ORF1 and ORF2 consist of 5,940 and 453 nucleotides, respectively. Phylogenetic analysis revealed that NUP-24/JP was closely related to other SVV strains, particularly to U.S.A. strain NC-WGS93C/US. This finding suggests that SVV is prevalent in swine worldwide. Using a baculovirus expression system, we successfully produced virus-like particles, which would be useful for seroepidemiological studies of SVV.