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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.

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.

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.

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

The microbiota is known to influence the generation of hematopoietic progenitors, although the pathways underlying this process are still poorly understood. NOD1 and NOD2 are intracellular sensors for both Gram-positive and Gram-negative bacteria, but their role in steady-state hematopoiesis has never been characterized. We observed that stimulation with NOD1 or NOD2 ligand had no effect on the survival/proliferation of hematopoietic precursors. Nonetheless, NOD1, but not NOD2, ligand induced expression of multiple hematopoietic cytokines (interleukin-7 [IL-7], Flt3L, stem cell factor [SCF], ThPO, and IL-6) from bone marrow mesenchymal stromal cells (MSCs) in vitro. Moreover, in vivo administration of NOD1 ligand to germ-free mice restored the numbers of hematopoietic stem cells and precursors in bone marrow as well as serum concentrations of IL-7, Flt3L, SCF, and ThPO to the levels displayed by specific pathogen-free control animals. Based on these findings, we propose that NOD1 signaling in MSCs serves as an important pathway underlying the requirement for microbiota in the maintenance of steady-state hematopoiesis. This function is distinct from that triggered by lipopolysaccharide in both its broad effects on multiple progenitors and specific targeting of MSCs as cytokine producing intermediates.

Recent decades have witnessed a rapid worldwide increase in chronic inflammatory disorders such as asthma. CD4(+) T helper 2 cells play critical roles in the pathogenesis of allergic airway inflammation, and CD69 expression on activated CD4 T cells is required to induce allergic inflammation in tissues. However, how CD69 mechanistically controls allergic inflammation remains poorly defined. In lymphoid tissues, CD69 regulates cellular retention through inhibition of S1P1 expression and requires no specific ligands to function. In contrast, we show herein that myosin light chain (Myl) 9 and Myl12 are new functional ligands for CD69. Blockade of CD69-My19/12 interaction ameliorates allergic airway inflammation in ovalbumin-induced and house dust mite-induced mouse models of asthma. Within the inflamed mouse airways, we found that the expression of My19/12 was increased and that platelet-derived My19/12 localized to the luminal surface of blood vessels and formed intravascular netlike structures. Analysis of nasal polyps of eosinophilic chronic rhinosinusitis patients revealed that My19/12 expression was increased in inflammatory lesions and was distributed within net-like structures in the intravascular space. In addition, we detected My19/12 in perivascular spaces where many CD69(+) cells were positioned within My19/12 structures. Thus, CD69-My19/12 interaction is a key event in the recruitment of activated CD69(+) T cells to inflamed tissues and could be a therapeutic target for intractable airway inflammatory diseases. Refereed/Peer-reviewed

Sox4 is a transcription factor that regulates various developmental processes. Here we show that Sox4 was induced by TGF-β and negatively regulated the transcription factor GATA-3, the master regulator of function of T helper type 2 (T H 2) cells, by two distinct mechanisms. First, Sox4 bound directly to GATA-3, preventing its binding to GATA-3 consensus DNA sequences. Second, Sox4 bound to the promoter region of the gene encoding interleukin 5 (IL-5), a T H 2 cytokine, and prevented binding of GATA-3 to this promoter. T H 2 cell-driven airway inflammation was modulated by alterations in Sox4 expression. Thus, Sox4 acted as a downstream target of TGF-β to inhibit GATA-3 function, T H 2 differentiation and T H 2 cell-mediated inflammation. Refereed/Peer-reviewed

Aims CD69 is an early activation marker in lymphocytes and an important signal transmitter in inflammatory processes. However, its role in acute lung injury (ALI) is still unknown. We used a lipopolysaccharide (LPS)-induced mouse model of ALI to study the role of macrophage-surface CD69 in this condition. Main methods We investigated bronchoalveolar lavage fluid (BALF) cell subpopulations, myeloperoxidase levels in lung homogenates, lung pathology, and lung oedema in CD69-deficient (CD69−/−) mice 24 h after LPS instillation. We also determined cytokine/chemokine expression levels in BALF and macrophage culture supernatant from CD69−/− and wild type (WT) mice. Also, we investigated CD69, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein (MIP)-2 localization in the lungs after LPS administration. Furthermore, we examined the effect of anti-CD69 antibody on LPS-induced cytokine/chemokine release from cultured macrophages. Key findings Our study shows that intratracheal instillation of LPS-induced neutrophilic infiltration, histopathological changes, myeloperoxidase positivity, and oedema in the lung to a lower degree in CD69−/− mice than in WT mice. The immunoreactivities for CD69, KC and MIP2 were induced in the lung of WT mice instilled with LPS and were predominantly localized to the macrophages. Moreover, the cytokine/chemokine expression profile between the two genotypes of cultured macrophages in response to LPS was similar to that observed in the BALF. In addition, anti-CD69 antibody inhibited the LPS-induced cytokine/chemokine expression. Significance These results suggest that CD69 on macrophages plays a crucial role in the progression of LPS-induced ALI and may be a potentially useful target in the therapy for ALI.

Cluster of differentiation 69 (CD69) has been identified as a lymphocyte early activation marker, and recent studies have indicated that CD69 mediates intracellular signals and plays an important role in various inflammatory diseases. Cigarette smoke (CS) is a strong proinflammatory stimulus that induces the release of proinflammatory mediators by recruiting macrophages and neutrophils into the lung tissue, and is one of the main risk factors for a number of chronic diseases. However, the potential role of CD69 in CS-induced pulmonary inflammation has not been determined. To address to this question, CD69-deficient (KO) and wild-type (WT) mice were subjected to CS-induced acute pulmonary inflammation. After the exposure with CS, the expression of CD69 in the lung of WT mice was significantly induced, it was predominantly observed in macrophages. In conjunction with this phenomenon, neutrophil and macrophage cell counts, and expression of several cytokines were significantly higher in the bronchoalveolar lavage fluid (BALF) of CS-exposed WT mice compared with air-exposed WT mice. Likewise, the CS-induced accumulation of inflammatory cells and cytokines expression were significantly lower in CD69-KO mice than in WT mice. These results suggest that CD69 on macrophages is involved in CS-induced acute pulmonary inflammation.

Studies of human asthma and of animal models of allergic airway inflammation revealed a crucial role for Th2 cells in the pathogenesis of allergic asthma. Kruppel-type zinc finger proteins are the largest family of a regulatory transcription factor for cellular development and function. Zinc finger protein (Zfp) 35 is an 18-zinc finger motif-containing Kruppel-type zinc finger protein, while its function remains largely unknown. The aim of this study was to clarify the role of Zfp35 in the pathogenesis of Th2-dependent allergic inflammation, such as allergic asthma. We examined airway eosinophilic inflammation and hyperresponsiveness in two mouse models, which use our newly generated Zfp35-deficient (Zfp35−/−) mice and adoptive transfer of cells. In Zfp35−/− mice, Th2 cell differentiation, Th2 cytokine production, eosinophilic inflammation, and airway hyperresponsiveness were substantially enhanced. Furthermore, adoptive transfer of Ag-sensitized Zfp35−/− CD4 T cells into the asthmatic mice resulted in enhanced airway inflammation and airway hyperresponsiveness. These results indicate that Zfp35 controls Th2 cell differentiation, allergic airway inflammation, and airway hyperresponsiveness in a negative manner. Thus, Zfp35 may control Th2-dependent diseases, such as allergic asthma.

Airway hypersensitive reaction (AHR) is an animal model for asthma, which is caused or enhanced by environmental factors such as allergen exposure. However, the precise mechanisms that drive AHR remain unclear. We identified a novel subset of natural killer T (NKT) cells that expresses the interleukin 17 receptor B (IL-17RB) for IL-25 (also known as IL-17E) and is essential for the induction of AHR. IL-17RB is preferentially expressed on a fraction of CD4(+) NKT cells but not on other splenic leukocyte populations tested. IL-17RB(+) CD4(+) NKT cells produce predominantly IL-13 and Th2 chemokines upon stimulation with IL-25 in vitro. IL-17RB(+) NKT cells were detected in the lung, and depletion of IL-17RB(+) NKT cells by IL-17RB-specific monoclonal antibodies or NKT cell-deficient Jalpha18(-/-) mice failed to develop IL-25-dependent AHR. Cell transfer of IL-17RB(+) but not IL-17RB(-) NKT cells into Jalpha18(-/-) mice also successfully reconstituted AHR induction. These results strongly suggest that IL-17RB(+) CD4(+) NKT cells play a crucial role in the pathogenesis of asthma.

Allergic airway inflammation develops in the context of innate immune cells that express Toll-like receptors (TLRs). TLRs recognize microbial components and evoke diverse responses in immune and other respiratory cells through distinct signaling pathways. Bacterial and viral infection in the airway modulates the extent of allergic inflammation. TLR stimulation controls T helper (Th) 1, Th2, and Th17 cell differentiation, cytokine production in mast cells, and activation of eosinophils via direct and indirect pathways. TLR signals in dendritic cells increase expression of major histocompatibility complex proteins and T-cell coreceptors, resulting in greater T-cell activation with Th1 bias. TLR signals in mast cells increase their release of IL-5, and TLR signals in airway epithelial cells enhance airway generation of proallergic cytokines. Although these responses play an important protective role in infection, they may exacerbate allergic inflammation. Under some conditions, TLR stimulation, especially via TLR9, reduces Th2-dependent allergic inflammation through induction of Th1 responses. Therefore, understanding the regulatory role of TLRs in the pathogenesis of allergic airway inflammation may shed light on improving inflammation control in asthmatic patients.

Background: In the last few decades, numerous chemical compounds have been produced as a result of industrial development. At the same time, the number of atopic dermatitis (AD) patients has been increasing. It has been reported that tributyltin (TBT) compounds have effects not only on the reproductive system but also on the immune system. Objective: To investigate whether TBT has an effect on AD, we fed a diet containing TBT to DS-Nh mice, which spontaneously developed dermatitis under conventional conditions. Methods: DS-Nh mice fed TBT or a control diet were examined for skin changes, number of Staphylococcus aureus on the skin and serum IgE levels. To determine Th1/Th2 cytokine production by lymphocytes, lymphocytes of DS-Nh mice fed TBT and of controls were cultured with staphylococcal enterotoxin B and cytokine levels in the supernatants were measured by ELISA. We observed not only spontaneous dermatitis but also dermatitis induced by sensitization with 2,4,6-trinitrochlorobenzene (TNCB). Results and Conclusion: The AD-like lesions induced by TNCB sensitization were more severe in the mice fed TBT than in those fed the control diet. A greater increase in S. aureus on the skin was observed in the mice fed TBT than in the mice fed the control diet. A decrease in IFN-γ production and an increase in IL-5 and IL-13 production were observed in the mice fed the TBT diet and treated with TNCB. These findings suggest that the increase in S. aureus and the enhancement of Th2 response induced by TBT exacerbate the AD-like lesions in mice treated with TNCB.

Schnurri (Shn) is a large zinc finger protein implicated in cell growth, signal transduction, and lymphocyte development. Vertebrates possess at least three Shn orthologues (Shn-1, Shn-2, and Shn-3), which appear to act within the bone morphogenetic protein, transforming growth factor beta, and activin signaling pathways. However, the physiological functions of the Shn proteins remain largely unknown. In Shn-2-deficient mice, mature peripheral T cells exhibited normal anti-T cell receptor-induced proliferation, although there was dramatic enhancement in the differentiation into T helper type (Th)2 cells and a marginal effect on Th1 cell differentiation. Shn-2-deficient developing Th2 cells showed constitutive activation of nuclear factor kappaB (NF-kappaB) and enhanced GATA3 induction. Shn-2 was able to compete with p50 NF-kappaB for binding to a consensus NF-kappaB motif and inhibit NF-kappaB-driven promoter activity. Thus, Shn-2 plays a crucial role in the control of Th2 cell differentiation by regulating NF-kappaB function.

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. Refereed/Peer-reviewed

Myeloperoxidase-specific anti-neutrophil cytoplasmic antibody (MPO-ANCA) is associated with rapidly progressive glomerulonephritis (RPGN) and glomerular crescent formation. Pathogenic factors in RPGN were analyzed by using SCG/Kj mice, which spontaneously develop MPO-ANCA-associated RPGN. The serum concentration of soluble IL-6R was determined by using ELISA and those of another 23 cytokines and chemokines by Bio-Plex analysis. Sections of frozen kidney tissue were examined by fluorescence microscopy and the CD3(+) B220(+) T cell subset in the spleen determined by a flow cytometry. Concentrations of IL-6 and monocyte chemotactic protein-1 were significantly correlated with the percentages of crescent formation. Anti-IL-6R antibody, which has been effective in patients with rheumatoid arthritis, was administered to SCG/Kj mice to elucidate the role of IL-6 in the development of RPGN. MPO-ANCA titers decreased after administration of anti-IL-6R antibody, but not titers of mizoribine, which is effective in Kawasaki disease model mice. These results suggest that IL-6-mediated signaling is involved in the production of MPO-ANCA.

GATA binding protein 3 (Gata3) is a GATA family transcription factor that controls differentiation of naïve CD4 T cells into T helper 2 (Th2) cells. However, it is unknown how Gata3 simultaneously activates Th2-specific genes while repressing those of other Th lineages. Here we show that chromodomain helicase DNA-binding protein 4 (Chd4) forms a complex with Gata3 in Th2 cells that both activates Th2 cytokine transcription and represses the Th1 cytokine IFN-γ. We define a Gata3/Chd4/p300 transcriptional activation complex at the Th2 cytokine loci and a Gata3/Chd4–nucleosome remodeling histone deacetylase repression complex at the Tbx21 locus in Th2 cells. We also demonstrate a physiological role for Chd4 in Th2-dependent inflammation in an in vivo model of asthmatic inflammation. Thus, Gata3/Chd4 forms functionally distinct complexes, which mediate both positive and negative gene regulation to facilitate Th2 cell differentiation.

After antigen encounter by CD4 + Tcells, polarizing cytokines induce the expression of master regulators that control differentiation. Inactivation of the histone methyltransferase Ezh2 was found to specifically enhance T helper 1 (Th1) and Th2 cell differentiation and plasticity. Ezh2 directly bound and facilitated correct expression of Tbx21 and Gata3 in differentiating Th1 and Th2 cells, accompanied by substantial trimethylation at lysine 27 of histone 3 (H3K27me3). In addition, Ezh2 deficiency resulted in spontaneous generation of discrete IFN-γ and Th2 cytokine-producing populations in nonpolarizing cultures, and under these conditions IFN-γ expression was largely dependent on enhanced expression of the transcription factor Eomesodermin. Invivo, loss of Ezh2 caused increased pathology in a model of allergic asthma and resulted in progressive accumulation of memory phenotype Th2 cells. This study establishes a functional link between Ezh2 and transcriptional regulation of lineage-specifying genes in terminally differentiated CD4 + Tcells. Refereed/Peer-reviewed

The microbiota is required for optimal hematopoiesis. When compared to specific-pathogen free (SPF) mice, germ free (GF) animals display decreased numbers of hematopoietic stem cells (HSC), common myeloid progenitors (CMP) and common lymphoid progenitors (CLP) in bone marrow. Muropeptides produced by both gram-negative and gram-positive bacteria are important agonists of the innate immune response and are recognized by the intracellular pattern-recognition receptors NOD1 and NOD2. In the present study, we examined both direct and indirect effects of NOD signaling on hematopoietic homeostasis. While stimulation with NOD1 or NOD2 ligands had no effect on survival/proliferation of HSC, CMP and CLP in vitro, exposure of bone marrow-derived stroma cells (BMSC) to NOD1, but not NOD2, ligand induced expression of the differentiation factors SCF, IL-7, IL-3, Thpo and IL-6. Interestingly LPS, which is known to act directly on hematopoietic precursors, selectively induced only IL-6 in BMSC. To test the effects of NOD1 ligand in vivo, we compared groups of GF animals with and without peroral NOD1 ligand administration. NOD1 ligand treatment restored to normal levels serum concentrations of SCF, Thpo and IL-6, as well as the numbers of HSC, CMP and CLP in bone marrow. Taken together, these findings demonstrate that NOD1 ligand induces BMSC to produce cytokines that regulate the size of the major hematopoietic precursor pools. Thus, NOD1 signaling appears to be a major factor underlying the requirement for the microbiota in the maintenance of steady-state hematopoiesis. This work was supported by the Intramural Research Program of the National Institute of Allergy and Infectious diseases.

CD69 is a membrane molecule transiently expressed on activated lymphocytes, and its selective expression in inflammatory infiltrates suggests that it plays a role in the pathogenesis of inflammatory diseases. In this study, we used CD69-deficient (CD69 KO) mice to assess the role of CD69 in the pathogenesis of dextran sulphate sodium (DSS)-induced acute and chronic colitis. The severity of colitis was assessed by the survival rate, clinical signs, colon length, histological examination and the expression of cytokines and chemokines in the large intestines. Both acute and chronic colitis were attenuated in the CD69 KO mice, as reflected by the lower lethality, weight loss, clinical signs, and improved histological findings. CD69(+) cells infiltrated extensively into the inflamed mucosa of the colon in WT mice after DSS treatment. Experiments with the transfer of WT CD4 T cells into CD69 KO mice restored the induction of colitis. The administration of an anti-CD69 antibody also inhibited the induction of the DSS-induced colitis. These results indicate that CD69 expressed on CD4 T cells plays an important role in the pathogenesis of DSS-induced acute and chronic colitis, and that CD69 could be a possible therapeutic target for colitis.

To develop more effective vaccines and strategies to regulate chronic inflammatory diseases, it is important to understand the mechanisms of immunological memory. Factors regulating memory CD4 + T helper (Th)-cell pool size and function remain unclear, however. We show that activation of type I invariant natural killer T (iNKT) cells with glycolipid ligands and activation of type II natural killer T (NKT) cells with the endogenous ligand sulfatide induced dramatic proliferation and expansion of memory, but not naïve, CD4 T cells. NKT cell-induced proliferation of memory Th1 and Th2 cells was dependent largely on the production of IL-2, with Th2-cell proliferation also affected by loss of IL-4. Type II NKT cells were also required for efficient maintenance of memory CD4 T cells in vivo. Activation of iNKT cells resulted in up-regulation of IFN-γ expression by memory Th2 cells. These IFN-γ–producing memory Th2 cells showed a decreased capability to induce Th2 cytokines and eosinophilic airway inflammation. Thus, activated NKT cells directly regulate memory CD4 T-cell pool size and function via the production of cytokines in vivo.

Memory T-helper (Th) lymphocytes are crucial for the maintenance of acquired immunity to eliminate infectious pathogens. We have previously demonstrated that most memory Th lymphocytes reside and rest on stromal niches of the bone marrow (BM). Little is known, however, regarding the molecular basis for the generation and maintenance of BM memory Th lymphocytes. Here we show that CD69-deficient effector CD4 T lymphocytes fail to relocate into and persist in the BM and therefore to differentiate into memory cells. Consequently, CD69-deficient CD4 T cells fail to facilitate the production of high-affinity antibodies and the generation of BM long-lived plasma cells in the late phase of immune responses. Thus, CD69 is critical for the generation and maintenance of professional memory Th lymphocytes, which can efficiently help humoral immunity in the late phase. The deficit of immunological memory in CD69-deficient mice also highlights the essential role of BM for the establishment of Th memory. Refereed/Peer-reviewed

Schnurri (Shn)-2 is a large zinc finger-containing protein implicated in cell growth, signal transduction and lymphocyte development. Here, we report that Shn-2-deficient (Shn-2 -/- ) mice develop CD3-positive lymphoma spontaneously. In Shn-2 -/- mice, we observed decreased cytotoxicity of natural killer (NK) cells accompanied by decreased expression of perforin and granzyme-B. In addition, phosphorylation of signal transducer and activator of transcription (STAT) 5 was reduced in Shn-2 -/- NK cells, while phosphorylation of STAT3 and protein expression of nuclear factor-κB p65 subunit were enhanced in Shn-2 -/- NK cells. Moreover, cell-surface expression of activation molecules such as CD27, CD69 and CD122 were decreased on Shn-2 -/- NK cells. Thus, Shn-2 is considered to play an important role in the activation and function of NK cells and the development of T cell lymphoma in vivo. Refereed/Peer-reviewed

Background Cluster of differentiation 69 (CD69), an early activation marker antigen on T and B cells, is also expressed on activated macrophages and neutrophils, suggesting that CD69 may play a role in inflammatory diseases. To determine the effect of CD69 deficiency on bleomycin(BLM)-induced lung injury, we evaluated the inflammatory response following intratracheal BLM administration and the subsequent fibrotic changes in wild type (WT) and CD69-deficient (CD69-/-) mice. Methods The mice received a single dose of 3 mg/kg body weight of BLM and were sacrificed at 7 or 14 days post-instillation (dpi). Lung inflammation in the acute phase (7 dpi) was investigated by differential cell counts and cytokine array analyses of bronchoalveolar lavage fluid. In addition, lung fibrotic changes were evaluated at 14 dpi by histopathology and collagen assays. We also used reverse transcription polymerase chain reaction to measure the mRNA expression level of transforming growth factor β1 (TGF-β1) in the lungs of BLM-treated mice. Results CD69-/- mice exhibited less lung damage than WT mice, as shown by reductions in the following indices: (1) loss of body weight, (2) wet/dry ratio of lung, (3) cytokine levels in BALF, (4) histological evidence of lung injury, (5) lung collagen deposition, and (6) TGF-β1 mRNA expression in the lung. Conclusion The present study clearly demonstrates that CD69 plays an important role in the progression of lung injury induced by BLM.

Con A-induced hepatitis has been used as a model of human autoimmune or viral hepatitis. During the process of identifying immunologically bioactive proteins in human plasma, we found that apolipoprotein A-II (ApoA-II), the second major apolipoprotein of high-density lipoprotein, inhibited the production of IFN-γ by Con A-stimulated mouse and human CD4 T cells. Con A-induced hepatitis was attenuated by the administration of ApoA-II. The beneficial effect of ApoA-II was associated with reduced leukocyte infiltration and decreased production of T cell-related cytokines and chemokines in the liver. ApoA-II inhibited the Con A-induced activation of ERK–MAPK and nuclear translocation of NFAT in CD4 T cells. Interestingly, exacerbated hepatitis was observed in ApoA-II–deficient mice, indicating that ApoA-II plays a suppressive role in Con A-induced hepatitis under physiological conditions. Moreover, the administration of ApoA-II after the onset of Con A-induced hepatitis was sufficient to suppress disease. Thus, the therapeutic effect of ApoA-II could be useful for patients with CD4 T cell-related autoimmune and viral hepatitis.

Repressor of GATA (ROG) inhibits Th2 cell differentiation and allergic airway inflammation in the lung. To determine the role of ROG in the pathogenesis of contact hypersensitivity (CHS), a hapten-induced mouse model of CHS using ROG Tg and ROG-deficient (ROG ―/― ) was used. ROG Tg mice showed little ear swelling, while ROG ―/― mice showed enhanced ear swelling in comparison to wild type mice. Interstitial edema and mast cell degranulation at the local inflammation sites were mild in ROG Tg mice and exacerbated in ROG ―/― mice. In addition, the serum total IgE and hapten-specific IgG1 levels were increased in ROG ―/― mice. Adoptive transfer of ROG ―/― CD4 + T cells exacerbated CHS in wild type mice, while transfer of ROG Tg CD4 + T cells resulted in the attenuation of CHS. These results indicate ROG negatively regulates the induction of CHS by controlling the CD4 + T cell-mediated allergic responses, including IgE generation and mast cell degranulation.

T helper 2 (Th2) cells play crucial roles in the development of allergic asthma, while various distinct cell populations also contribute to the pathogenesis of the disease. Invariant natural killer T (iNKT) cells produce large amounts of cytokines such as IL-4 and IFNγ upon stimulation with a ligand, α-galactosylceramide, and regulate various immune responses. Recently, a critical role of iNKT cells in the mouse model of asthma and also in asthma patients has been reported, while some contradictory results have also been described. Here, we summarize the experimental results in mouse and human systems, and discuss the current understanding of the role of NKT cells in the pathogenesis of asthma, including a possible mechanism by which iNKT cells are activated in asthma patients.

Polycomb group (PcG) gene products regulate the maintenance of homeobox gene expression in Drosophila and vertebrates. In the immune system, PcG molecules control cell cycle progression of thymocytes, Th2 cell differentiation, and the generation of memory CD4 T cells. In this paper, we extended the study of PcG molecules to the regulation of in vivo Th2 responses, especially allergic airway inflammation, by using conditional Ring1B-deficient mice with a CD4 T cell-specific deletion of the Ring1B gene (Ring1B−/− mice). In Ring1B−/− mice, CD4 T cell development appeared to be normal, whereas the differentiation of Th2 cells but not Th1 cells was moderately impaired. In an Ag-induced Th2-driven allergic airway inflammation model, eosinophilic inflammation was attenuated in Ring1B−/− mice. Interestingly, Ring1B−/− effector Th2 cells were highly susceptible to apoptosis in comparison with wild-type effector Th2 cells in vivo and in vitro. The in vitro experiments revealed that the expression of Bim was increased at both the transcriptional and protein levels in Ring1B−/− effector Th2 cells, and the enhanced apoptosis in Ring1B−/− Th2 cells was rescued by the knockdown of Bim but not the other proapoptotic genes, such as Perp, Noxa, or Bax. The enhanced apoptosis detected in the transferred Ring1B−/− Th2 cells in the lung of the recipient mice was also rescued by knockdown of Bim. Therefore, these results indicate that Ring1B plays an important role in Th2-driven allergic airway inflammation through the control of Bim-dependent apoptosis of effector Th2 cells in vivo.

Airway inflammation and airway hyperresponsiveness are central issues in the pathogenesis of asthma. CD69 is a membrane molecule transiently expressed on activated lymphocytes, and its selective expression in inflammatory infiltrates suggests that it plays a role in the pathogenesis of inflammatory diseases. In CD69-deficient mice, OVA-induced eosinophilic airway inflammation, mucus hyperproduction, and airway hyperresponsiveness were attenuated. Cell transfer of Ag-primed wild-type but not CD69-deficient CD4 T cells restored the induction of allergic inflammation in CD69-deficient mice, indicating a critical role of CD69 expressed on CD4 T cells. Th2 responses induced by CD69-deficient CD4 T cells in the lung were attenuated, and the migration of CD4 T cells into the asthmatic lung was severely compromised. The expression of VCAM-1 was also substantially altered, suggesting the involvement of VCAM-1 in the CD69-dependent migration of Th2 cells into the asthmatic lung. Interestingly, the administration of anti-CD69 Ab inhibited the induction of the OVA-induced airway inflammation and hyperresponsiveness. This inhibitory effect induced by the CD69 mAb was observed even after the airway challenge with OVA. These results indicate that CD69 plays a crucial role in the pathogenesis of allergen-induced eosinophilic airway inflammation and hyperresponsiveness and that CD69 could be a possible therapeutic target for asthmatic patients.

Background: : Some polyphenols possess anti-allergic activities. Naringenin chalcone is one of the polyphenols that is present in the skin of red tomatoes. In this study, we investigated the effect of naringenin chalcone in allergic responses in vivo using an experimental mouse model system of allergic asthma. Methods: : Allergic airway inflammation was induced in mice by sensitization and challenge with ovalbumin. Naringenin chalcone was orally administrated every day during the course of the experiment. Airway hyperreactivity, the eosinophilic infiltration in the bronchioalveolar lavage fluid and Th2 cytokine production from splenic CD4 T cells were assessed. Results: : Eosinophilic airway inflammation, airway hyperreactivity and Th2 cytokine production from CD4 T cells were significantly suppressed in mice that were treated with naringenin chalcone. Hyperproduction of mucus was slightly reduced. Conclusions: : The results of this study suggest that naringenin chalcone suppresses asthmatic symptoms by inhibiting Th2 cytokine production from CD4 T cells. Thus, naringenin chalcone may be a useful supplement for the suppression of allergic symptoms in humans.

Background Studies of human asthma and of animal models of allergic inflammation/asthma highlight a crucial role for T H 2 cells in the pathogenesis of allergic asthma. Repressor of GATA (ROG) is a POZ (BTB) domain–containing Kruppel-type zinc finger family (or POK family) repressor. A repressive function to GATA3, a master transcription factor for T H 2 cell differentiation, is indicated. Objective The aim of this study was to clarify the regulatory roles of ROG in the pathogenesis of T H 2-driven allergic diseases, such as allergic asthma. Methods We examined allergic airway inflammation and airway hyperresponsiveness (AHR) in 3 different mouse models, which use either ROG-deficient ( ROG −/− ) mice, ROG transgenic mice, or adoptive transfer of cells. Results In ROG −/− mice T H 2 cell differentiation, T H 2 responses, eosinophilic airway inflammation, and AHR were enhanced. In ROG transgenic mice the levels of eosinophilic airway inflammation and AHR were dramatically reduced. Furthermore, adoptive transfer of T H 2 cells with increased or decreased levels of ROG expression into the asthmatic mice resulted in reduced or enhanced airway inflammation, respectively. Conclusion These results indicate that ROG regulates allergic airway inflammation and AHR in a negative manner, and thus ROG might represent another potential therapeutic target for the treatment of asthmatic patients.

Schnurri (Shn)-2 is a large zinc finger-containing protein, which plays a critical role in cell growth, signal transduction and lymphocyte development. In Shn-2-deficient (Shn-2(-/-)) CD4 T cells, the activation of nuclear factor-kappaB is up-regulated and their ability to differentiate into Th2 is enhanced. Here, we extend our investigation and demonstrate that Shn-2 regulates Th2 responses in vivo using an ovalbumin-induced allergic asthma model. Eosinophilic inflammation, mucus hyperproduction and airway hyperresponsiveness (AHR) were all enhanced in Shn-2(-/-) mice. Moreover, eosinophilic infiltration and AHR were enhanced in mice given a transfer of Shn-2(-/-) effector Th2. Shn-2 in Th2 is thus considered to play an important role as a negative regulator in allergic airway inflammation.

Valpha14 natural killer T (NKT) cells produce large amounts of both IL-4 and IFN-gamma upon stimulation with a ligand, alpha-galactosylceramide (alpha-GalCer), and play a crucial role in various immune responses, including allergic reactions. Interestingly, Valpha14 NKT cells are not essential for the induction of specific IgE response but they instead tend to induce suppression of specific IgE upon alpha-GalCer activation in vivo. The suppression in the IgE production is not detected either in Valpha14 NKT cell-deficient mice or in IFN-gamma-deficient mice. Therefore, activated Valpha14 NKT cells are able to exert a potent suppressive activity on Th2 cell differentiation and subsequent IgE production by producing a large amount of IFN-gamma. In an OVA-induced asthma model, alpha-GalCer administration inhibited airway inflammation and airway hyperreactivity by IFN-gamma from activated Valpha14 NKT cells, thus suggesting the negative regulation of Th2-responses by the activated Valpha14 NKT cells.

In the last few decades, numerous chemical compounds have been produced as a result of industrial development. At the same time, the number of atopic dermatitis (AD) patients has been increasing. It has been reported that tributyltin (TBT) compounds have effects not only on the reproductive system but also on the immune system.To investigate whether TBT has an effect on AD, we fed a diet containing TBT to DS-Nh mice, which spontaneously developed dermatitis under conventional conditions.DS-Nh mice fed TBT or a control diet were examined for skin changes, number of Staphylococcus aureus on the skin and serum IgE levels. To determine Th1/Th2 cytokine production by lymphocytes, lymphocytes of DS-Nh mice fed TBT and of controls were cultured with staphylococcal enterotoxin B and cytokine levels in the supernatants were measured by ELISA. We observed not only spontaneous dermatitis but also dermatitis induced by sensitization with 2,4,6-trinitrochlorobenzene (TNCB).The AD-like lesions induced by TNCB sensitization were more severe in the mice fed TBT than in those fed the control diet. A greater increase in S. aureus on the skin was observed in the mice fed TBT than in the mice fed the control diet. A decrease in IFN-gamma production and an increase in IL-5 and IL-13 production were observed in the mice fed the TBT diet and treated with TNCB. These findings suggest that the increase in S. aureus and the enhancement of Th2 response induced by TBT exacerbate the AD-like lesions in mice treated with TNCB.

Upon encountering antigen, naïve CD4 T cells rapidly differentiate into discrete subsets of effector T helper (Th) cells that direct immune responses to different types of infection. Polarizing cytokines induce the expression of lineage-specifying genes (Tbx21 for Th1 cells and Gata3 for Th2 cells) that control differentiation. We found that the histone H3K27 methyltransferase Ezh2 controls differentiation of Th1 and Th2 cells, and that inactivation of Ezh2 enhances plasticity of both of these subsets. Tbx21 and Gata3 experienced large changes in Ezh2 occupancy during Th differentiation, and inactivation of Ezh2 depleted H3K27-trimethylation (H3K27-Me3) at these loci. Additionally, loss of Ezh2 caused increased pathology in a mouse model of allergic asthma and progressive accumulation of memory phenotype Th2 cells in vivo. This study establishes a functional link between Ezh2 and transcriptional regulation of lineage-specifying genes in terminally differentiated peripheral T cells via H3K27-Me3. These data may therefore contribute to the development of therapies that target this pathway to enhance or repress immune responses in human diseases.

Schnurri-2 (Shn-2) is a large zinc-finger containing protein, and it plays a critical role in cell growth, signal transduction and lymphocyte development. In Shn-2-deficient CD4 T cells, the activation of NF-kB was upregulated and their ability to differentiate into Th2 cells was enhanced. We herein demonstrate that Th1 and Th2 memory cells are not properly generated from Shn-2-deficient effector Th1/Th2 cells. Even a week after the transfer of effector Th1/Th2 cells into syngeneic mice, a dramatic decrease in the number of Shn-2-deficient donor T cells was detected particularly in the lymphoid organs. The transferred Shn-2-deficient Th1/Th2 cells express higher levels of the activation marker CD69. No significant defect in the BrdU incorporation in the Shn-2-deficient transferred CD4 T cells was observed. The numbers of apoptotic cells were selectively higher in Shn-2-deficient donor Th1/Th2 cell population. Moreover, Shn-2-deficient effector Th1 and Th2 cells showed an increased susceptibility to cell death in in vitro cultures with increased expression of FasL. Transfer of Th2 effector cells over-expressing the p65 subunit of NF-kB resulted in a decreased number of p65-expressing cells in the lymphoid organs. As expected, T cell-dependent antibody responses after in vivo immunization of Shn-2-deficient mice were significantly reduced. Thus, Shn-2 appears to control the generation of memory Th1/Th2 cells through a change in their susceptibility to cell death.