Junpei Suzuki

Sox5 and c-Maf cooperatively induce Th17 cell differentiation via RORγt induction as downstream targets of Stat3

A novel isoform of Sox5, Sox5t, and c-Maf activate RORγt to induce Th17 cells. Sox5−/− mice exhibit impaired Th17 differentiation and are thus resistant to EAE and delayed-type hypersensitivity.

The Menin–Bach2 axis is critical for regulating CD4 T-cell senescence and cytokine homeostasis

Although CD4 T-cell senescence plays an important role in immunosenescence, the mechanism behind this process remains unclear. Here we show that T cell-specific Menin deficiency results in the premature senescence of CD4 T cells, which is accompanied by the senescence-associated secretory phenotype after antigenic stimulation and dysregulated cytokine production. Menin is required for the expansion and survival of antigen-stimulated CD4 T cells in vivo and acts by targeting Bach2, which is known to regulate immune homeostasis and cytokine production. Menin binds to the Bach2 locus and controls its expression through maintenance of histone acetylation. Menin binding at the Bach2 locus and the Bach2 expression are decreased in the senescent CD4 T cells. These findings reveal a critical role of the Menin-Bach2 pathway in regulating CD4 T-cell senescence and cytokine homeostasis, thus indicating the involvement of this pathway in the inhibition of immunosenescence.

Identification of a New Pathway for Th1 Cell Development Induced by Cooperative Stimulation with IL-4 and TGF-β

IL-4 plays an important role in the induction of Th2 and Th9 cells, as well as in the inhibition of Th1 cell generation. We show that a combination of IL-4 and TGF-β augments the development of Th1 cells that express CD103 (CD103+ Th1 cells) if IFN-γ is present. The T-box–containing transcription factor eomesodermin (Eomes) is preferentially expressed in CD103+ Th1 cells and is involved in IFN-γ production. The induction of T-bet during early T cell activation is essential for the formation of the active chromatin at both the Eomes and IFN-γ gene loci. TGF-β is required for the induction of Eomes and CD103, as well as the inhibition of Th2 cytokine expression. In addition, IL-4 induces Eomes transcription through activation of the Stat6-signaling pathway. IFN-γ–producing CD103+ Th1 cells are detected in the intraepithelial lymphocytes of normal mice, and their numbers significantly decrease in Tbet- and Stat6-deficient mice. To our knowledge, these results represent the first molecular mechanism of IL-4/TGF-β–dependent augmentation of Th1 cell generation and raise the possibility that IL-4 and TGF-β simultaneously enhance the Th1 cell-mediated immune responses under certain cytokine conditions.

Bach2–Batf interactions control Th2-type immune response by regulating the IL-4 amplification loop

Although Bach2 has an important role in regulating the Th2-type immune response, the underlying molecular mechanisms remain unclear. We herein demonstrate that Bach2 associates with Batf and binds to the regulatory regions of the Th2 cytokine gene loci. The Bach2–Batf complex antagonizes the recruitment of the Batf–Irf4 complex to AP-1 motifs and suppresses Th2 cytokine production. Furthermore, we find that Bach2 regulates the Batf and Batf3 expressions via two distinct pathways. First, Bach2 suppresses the maintenance of the Batf and Batf3 expression through the inhibition of IL-4 production. Second, the Bach2–Batf complex directly binds to the Batf and Batf3 gene loci and reduces transcription by interfering with the Batf–Irf4 complex. These findings suggest that IL-4 and Batf form a positive feedback amplification loop to induce Th2 cell differentiation and the subsequent Th2-type immune response, and Bach2–Batf interactions are required to prevent an excessive Th2 response.

Generating a transgenic mouse line stably expressing human MHC surface antigen from a HAC carrying multiple genomic BACs

The human artificial chromosome (HAC) vector is a promising tool to improve the problematic suppression and position effects of transgene expression frequently seen in transgenic cells and animals produced by conventional plasmid or viral vectors. We generated transgenic mice maintaining a single HAC vector carrying two genomic bacterial artificial chromosomes (BACs) from human HLA-DR loci (DRA and DRB1). Both transgenes on the HAC in transgenic mice exhibited tissue-specific expression in kidney, liver, lung, spleen, lymph node, bone marrow, and thymus cells in RT-PCR analysis. Stable functional expression of a cell surface HLA-DR marker from both transgenes, DRA and DRB1 on the HAC, was detected by flow cytometric analysis of splenocytes and maintained through at least eight filial generations. These results indicate that the de novo HAC system can allow us to manipulate multiple BAC transgenes with coordinated expression as a surface antigen through the generation of transgenic animals.

Gfi1, a transcriptional repressor, inhibits the induction of the T helper type 1 programme in activated CD4 T cells

A transcriptional repressor Gfi1 promotes T helper type 2 (Th2) cell development and inhibits Th17 and inducible regulatory T‐cell differentiation. However, the role of Gfi1 in regulating Th1 cell differentiation and the Th1‐type immune response remains to be investigated. We herein demonstrate that Gfi1 inhibits the induction of the Th1 programme in activated CD4 T cells. The activated Gfi1‐deficient CD4 T cells spontaneously develop into Th1 cells in an interleukin‐12‐ and interferon‐γ‐independent manner. The increase of Th1‐type immune responses was confirmed in vivo in Gfi1‐deficient mice using a murine model of nickel allergy and delayed‐type hypersensitivity (DTH). The expression levels of Th1‐related transcription factors were found to increase in Gfi1‐deficient activated CD4 T cells. Tbx21, Eomes and Runx2 were identified as possible direct targets of Gfi1. Gfi1 binds to the Tbx21, Eomes and Runx2 gene loci and reduces the histone H3K4 methylation levels in part by modulating Lsd1 recruitment. Together, these findings demonstrate a novel regulatory role of Gfi1 in the regulation of the Th1‐type immune response.

Menin Plays a Critical Role in the Regulation of the Antigen-Specific CD8+ T Cell Response upon Listeria Infection

Menin, a tumor suppressor protein, is encoded by the MEN1 gene in humans. Certain germinal mutations of MEN1 induce an autosomal-dominant syndrome that is characterized by concurrent parathyroid adenomas and several other tumor types. Although menin is also expressed in hematopoietic lineages, its role in CD8+ T cells remains unclear. We generated Meninflox/flox CD4-Cre (Menin-KO) mice by crossing Meninflox/flox mice with CD4-Cre transgenic (Tg) mice to determine the role of menin in CD8+ T cells. Wild-type (WT) and Menin-KO mice were infected with Listeria monocytogenes expressing OVA to analyze the immune response of Ag-specific CD8+ T cells. Menin deficiency resulted in an impaired primary immune response by CD8+ T cells. On day 7, there were fewer Menin-KO OVA-specific CD8+ T cells compared with WT cells. Next, we adoptively transferred WT and Menin-KO OT-1 Tg CD8+ T cells into congenic recipient mice and infected them with L. monocytogenes expressing OVA to determine the CD8+ T cell–intrinsic effect. Menin-KO OT-1 Tg CD8+ T cells were outcompeted by the WT cells upon infection. Increased expression of Blimp-1 and T-bet, cell cycle inhibitors, and proapoptotic genes was observed in the Menin-KO OT-1 Tg CD8+ T cells upon infection. These data suggest that menin inhibits differentiation into terminal effectors and positively controls proliferation and survival of Ag-specific CD8+ T cells that are activated upon infection. Collectively, our study uncovered an important role for menin in the immune response of CD8+ T cells to infection.

A Novel Small Compound SH-2251 Suppresses Th2 Cell-Dependent Airway Inflammation through Selective Modulation of Chromatin Status at the Il5 Gene Locus

IL-5 is a key cytokine that plays an important role in the development of pathological conditions in allergic inflammation. Identifying strategies to inhibit IL-5 production is important in order to establish new therapies for treating allergic inflammation. We found that SH-2251, a novel thioamide-related small compound, selectively inhibits the differentiation of IL-5-producing Th2 cells. SH-2251 inhibited the induction of active histone marks at the Il5 gene locus during Th2 cell differentiation. The recruitment of RNA polymerase II, and following expression of the Th2 cell-specific intergenic transcripts around the Il5 gene locus was also inhibited. Furthermore, Th2 cell-dependent airway inflammation in mice was suppressed by the oral administration of SH-2251. Gfi1, a transcriptional repressor, was identified as a downstream target molecule of SH-2251 using a DNA microarray analysis. The Gfi1 expression dramatically decreased in SH-2251-treated Th2 cells, and the SH-2251-mediated inhibition of IL-5-producing Th2 cell differentiation was restored by transduction of Gfi1. Therefore, our study unearthed SH-2251 as a novel therapeutic candidate for allergic inflammation that selectively inhibits active histone marks at the Il5 gene locus.

The Transcriptional Repressor Gfi1 Plays a Critical Role in the Development of NKT1- and NKT2-Type iNKT Cells.

Gfi1 plays an important role in the development and maintenance of many hematopoietic linage cells. However, the impact of Gfi1-deficiency on the iNKT cell differentiation remains unclear. We herein demonstrate a critical role of Gfi1 in regulating the development of iNKT cell subsets. In the thymus of T cell-specific Gfi1-deficient mice, iNKT cells normally developed up to stage 2, while the number of stage 3 NK1.1pos iNKT cells was significantly reduced. Furthermore, CD4pos iNKT cells were selectively reduced in the peripheral organs of T cell-specific Gfi1-deficient mice. The α-GalCer-dependent production of IFN-γand Th2 cytokines, but not IL-17A, was severely reduced in T cell-specific Gfi1-deficient mice. In addition, a reduction of the α-GalCer-induced anti-tumor activity was observed in Gfi1-deficient mice. These findings demonstrate the important role of Gfi1 in regulating the development and function of NKT1- and NKT2-type iNKT cell subsets.

The tumor suppressor menin prevents effector CD8 T-cell dysfunction by targeting mTORC1-dependent metabolic activation

While menin plays an important role in preventing T-cell dysfunction, such as senescence and exhaustion, the regulatory mechanisms remain unclear. We found that menin prevents the induction of dysfunction in activated CD8 T cells by restricting the cellular metabolism. mTOR complex 1 (mTORC1) signaling, glycolysis, and glutaminolysis are augmented by menin deficiency. Rapamycin treatment prevents CD8 T-cell dysfunction in menin-deficient CD8 T cells. Limited glutamine availability also prevents CD8 T-cell dysfunction induced by menin deficiency, and its inhibitory effect is antagonized by α-ketoglutarate (α-KG), an intermediate metabolite of glutaminolysis. α-KG-dependent histone H3K27 demethylation seems to be involved in the dysfunction in menin-deficient CD8 T cells. We also found that α-KG activates mTORC1-dependent central carbon metabolism. These findings suggest that menin maintains the T-cell functions by limiting mTORC 1 activity and subsequent cellular metabolism.T cells can alter their metabolism during activation and differentiation. Here the authors show that the tumor suppressor menin regulates CD8 T-cell fate via the modulation of central carbon metabolism.