Interferon-regulatory factor 4 (IRF4) is essential for the development of T helper 2 (Th2) and Th17 cells. Herein, we report that IRF4 is also crucial for the development and function of an interleukin-9 (IL-9)-producing CD4(+) T cell subset designated Th9. IRF4-deficient CD4(+) T cells failed to develop into IL-9-producing Th9 cells, and IRF4-specific siRNA inhibited IL-9 production in wild-type CD4(+) T cells. Chromatin-immunoprecipitation (ChIP) analyses revealed direct IRF4 binding to the Il9 promoter in Th9 cells. In a Th9-dependent asthma model, neutralization of IL-9 substantially ameliorated asthma symptoms. The relevance of these findings is emphasized by the fact that the induction of IL-9 production also occurs in human CD4(+) T cells accompanied by the upregulation of IRF4. Our data clearly demonstrate the central function of IRF4 in the development of Th9 cells and underline the contribution of this T helper cell subset to the pathogenesis of asthma.
The quality of the adaptive immune response depends on the differentiation of distinct CD4(+) helper T cell subsets, and the magnitude of an immune response is controlled by CD4(+)Foxp3(+) regulatory T cells (Treg cells). However, how a tissue- and cell type-specific suppressor program of Treg cells is mechanistically orchestrated has remained largely unexplored. Through the use of Treg cell-specific gene targeting, we found that the suppression of allergic immune responses in the lungs mediated by T helper type 2 (TH2) cells was dependent on the activity of the protein kinase CK2. Genetic ablation of the β-subunit of CK2 specifically in Treg cells resulted in the proliferation of a hitherto-unexplored ILT3(+) Treg cell subpopulation that was unable to control the maturation of IRF4(+)PD-L2(+) dendritic cells required for the development of TH2 responses in vivo.
Inducible cAMP early repressor (ICER) is a transcriptional repressor, which, because of alternate promoter use, is generated from the 3′ region of the cAMP response modulator (Crem) gene. Its expression and nuclear occurrence are elevated by high cAMP levels in naturally occurring regulatory T cells (nTregs). Using two mouse models, we demonstrate that nTregs control the cellular localization of ICER/CREM, and thereby inhibit IL-2 synthesis in conventional CD4 + T cells. Ablation of nTregs in depletion of regulatory T-cell (DEREG) mice resulted in cytosolic localization of ICER/CREM and increased IL-2 synthesis upon stimulation. Direct contacts between nTregs and conventional CD4 + T cells led to nuclear accumulation of ICER/CREM and suppression of IL-2 synthesis on administration of CD28 superagonistic (CD28SA) Ab. In a similar way, nTregs communicated with B cells and induced the cAMPdriven nuclear localization of ICER/CREM. High levels of ICER suppressed the induction of nuclear factor of activated T cell c1 (Nfatc1) gene in T cells whose inducible Nfatc1 P1 promoter bears two highly conserved cAMP-responsive elements to which ICER/ CREM can bind. These findings suggest that nTregs suppress T-cell responses by the cAMP-dependent nuclear accumulation of ICER/ CREM and inhibition of NFATc1 and IL-2 induction.adenosin 3′,5′-cyclic monophospate | transcription | lymphocytes
Co-evolution of ticks and the vertebrate immune system has led to the development of immunosuppressive molecules that prevent immediate response of skin-resident immune cells to quickly fend off the parasite. Herein, we demonstrate that the tick-derived immunosuppressor sialostatin L restrains IL-9 production by mast cells while degranulation and IL-6 expression are both unaffected. In addition, the expression of IL-1β and IRF4 is strongly reduced in the presence of sialostatin L. Correspondingly, IRF4- or IL-1 receptor-deficient mast cells exhibit strong impairment in IL-9 production demonstrating the importance of IRF4 and IL-1 in the regulation of the Il9 locus in mast cells. Furthermore, IRF4 binds to the promoters of Il1b and Il9 suggesting that sialostatin L suppresses mast cell-derived IL-9 preferentially by inhibiting IRF4. In an experimental asthma model, mast cell-specific deficiency in IRF4 or administration of sialostatin L results in a strong reduction of asthma symptoms demonstrating the immunosuppressive potency of tick-derived molecules.
e21505 Background: Undifferentiated pleomorphic sarcoma, NOS (not otherwise specified) formerly known as MFH comprise about 15-20% of all soft tissue sarcomas (STS) in adults. This kind of sarcoma is characterized by low response to radiation or chemotherapy. Thus, surgery with the aim of R0-resection is still the cornerstone for a curative treatment regimen. However, surgery is not always possible. In the recent past, many efforts have been undertaken to refine chemotherapeutic options and to develop new drugs for targeted therapies, such as mTOR-inhibtors or tyrosine kinase inhibitors. Yet, the hoped break through is still lacking. In addition, the further development of entity-based new drugs is difficult due to the low incidence of STS and suitable reproducible animal models. Here, we present a new xenogenic transplantation model of a pleomorphic sarcoma in mice. Methods: After intraoperative resection of the sarcoma, a sarcoma-derived cell line was established. These cultured cells were injected s.c. (1x10E6 cells) in immunocompromised NOD/SCID γc-/- mice and in humanized NOD/SCID γc-/- mice. Results: Tumor growth was reproducibly seen after four to six weeks. When resected after 12 weeks, the xenogenic tumor presented the same histological and morphological characteristics as the original tumor. Tumor infiltrating lymphocytes were detected by immunhistochemical staining. Conclusions: This new xenogenic transplantation model can serve as a basis for the evaluation of manifold questions within the fields of oncology, tumor genetics and tumor immunology.
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