Search results for "Immune system"
showing 10 items of 2885 documents
Interferon-α Suppresses cAMP to Disarm Human Regulatory T Cells
2013
Abstract IFN-α is an antineoplastic agent in the treatment of several solid and hematologic malignancies that exerts strong immune- and autoimmune-stimulating activity. However, the mechanisms of immune activation by IFN-α remain incompletely understood, particularly with regard to CD4+CD25highFoxp+ regulatory T cells (Treg). Here, we show that IFN-α deactivates the suppressive function of human Treg by downregulating their intracellular cAMP level. IFN-α–mediated Treg inactivation increased CD4+ effector T-cell activation and natural killer cell tumor cytotoxicity. Mechanistically, repression of cAMP in Treg was caused by IFN-α–induced MAP–ERK kinase (MEK)/extracellular signal-regulated ki…
IAPs and cell migration.
2015
Inhibitors of apoptosis (IAPs) constitute a family of cell signaling regulators controlling several fundamental biological processes such as innate immunity, inflammation, cell death, cell proliferation, and cell differentiation. Increasing evidence from in vivo and in vitro studies indicate a function for IAPs in the modulation of invasive and migratory properties of cells. Here, we present and discuss the mechanisms whereby IAPs can control cell migration.
An immune escape screen reveals Cdc42 as regulator of cancer susceptibility to lymphocyte-mediated tumor suppression.
2007
Abstract Adoptive cellular immunotherapy inducing a graft-versus-tumor (GVT) effect is the therapeutic mainstay of allogeneic hematopoietic stem cell transplantation (ASCT) for high-risk leukemias. Autologous immunotherapies using vaccines or adoptive transfer of ex vivo–manipulated lymphocytes are clinically explored in patients with various cancer entities. Main reason for failure of ASCT and cancer immunotherapy is progression of the underlying malignancy, which is more prevalent in patients with advanced disease. Elucidating the molecular mechanisms contributing to immune escape will help to develop strategies for the improvement of immunologic cancer treatment. To this end, we have und…
Protective dendritic cell responses against listeriosis induced by the short form of the deubiquitinating enzyme CYLD are inhibited by full-length CY…
2015
The deubiquitinating enzyme CYLD is an important tumor suppressor and inhibitor of immune responses. In contrast to full-length CYLD, the immunological function of the naturally occurring short splice variant of CYLD (sCYLD) is insufficiently described. Previously, we showed that DCs, which lack full-length CYLD but express sCYLD, exhibit augmented NF-κB and DC activation. To explore the function of sCYLD in infection, we investigated whether DC-specific sCYLD regulates the pathogenesis of listeriosis. Upon Listeria monocytogenes infection of CD11c-Cre Cyld(ex7/8 fl/fl) mice, infection of CD8α(+) DCs, which are crucial for the establishment of listeriosis in the spleen, was not affected. Ho…
Bis(1H-indol-2-yl)methanones are effective inhibitors of FLT3-ITD tyrosine kinase and partially overcome resistance to PKC412A in vitro.
2009
Inhibition of the mutated fms-like tyrosine kinase 3 (FLT3) receptor tyrosine kinase is a promising therapeutic strategy in acute myeloid leukaemia (AML). However, development of resistance to FLT3 tyrosine kinase inhibitors (TKI), such as PKC412A, has been described recently. This observation may have an increasing impact on the duration of response and relapse rates in upcoming clinical trials employing FLT3-TKI. Herein we investigated two representatives of a novel class of FLT3-TKI: Bis(1H-indol-2-yl)methanones. Both compounds effectively induced apoptosis in FLT3-internal tandem duplicate (ITD)-transfected murine myeloid cells and in primary FLT3-ITD positive blasts. Combination of bot…
The Late Endosomal Adaptor Molecule p14 (LAMTOR2) Regulates TGFβ1-Mediated Homeostasis of Langerhans Cells
2014
Langerhans cells (LCs), a sub-population of dendritic cells (DCs) in the skin, participate in the regulation of immunity and peripheral tolerance. The adaptor molecule p14 is part of the late endosomal/lysosomal adaptor and mitogen-activated protein kinase and mammalian target of rapamycin (mTOR) activator/regulator (LAMTOR) complex, which mediates the activation of lysosome-associated extracellular signaling regulated kinase (ERK) and the mTOR cascade. In previous work, we demonstrated that CD11c-specific deficiency of p14 disrupts LC homeostasis by affecting the LAMTOR-mediated ERK and mTOR signaling. In this study, we extended our analysis on p14 deficiency specifically in LCs. Langerin-…
A20 expression in dendritic cells protects mice from LPS-induced mortality
2014
DCs contribute to immune homeostasis under physiological conditions and regulate the immune activation during infection. The deubiquitinase A20 inhibits the activation of NF-κB-dependent immune reactions, and prevents the hyperactivation of DCs under steady-state conditions. However, the role of DC-specific A20 under pathological conditions is unknown. Here, we demonstrate that upon injection of low-dose LPS, mice with DC-specific A20 deletion (CD11c-Cre A20(fl/fl) ) died within 6 h, whereas A20(fl/fl) controls survived. LPS-induced mortality in CD11c-Cre A20(fl/fl) mice was characterized by increased serum levels of IL-2, IL-10, IL-12, IFN-γ, and TNF. Upon LPS stimulation, the activation o…
Evaluation of the Role of Candida albicans Agglutinin-Like Sequence (Als) Proteins in Human Oral Epithelial Cell Interactions
2012
The fungus C. albicans uses adhesins to interact with human epithelial surfaces in the processes of colonization and pathogenesis. The C. albicans ALS (agglutinin-like sequence) gene family encodes eight large cell-surface glycoproteins (Als1-Als7 and Als9) that have adhesive function. This study utilized C. albicans Δals mutant strains to investigate the role of the Als family in oral epithelial cell adhesion and damage, cytokine induction and activation of a MAPK-based (MKP1/c-Fos) signaling pathway that discriminates between yeast and hyphae. Of the eight Δals mutants tested, only the Δals3 strain showed significant reductions in oral epithelial cell adhesion and damage, and cytokine pro…
Candida albicans Yeast and Hyphae are Discriminated by MAPK Signaling in Vaginal Epithelial Cells
2011
We previously reported that a bi-phasic innate immune MAPK response, constituting activation of the mitogen-activated protein kinase (MAPK) phosphatase MKP1 and c-Fos transcription factor, discriminates between the yeast and hyphal forms of Candida albicans in oral epithelial cells (ECs). Since the vast majority of mucosal Candida infections are vaginal, we sought to determine whether a similar bi-phasic MAPK-based immune response was activated by C. albicans in vaginal ECs. Here, we demonstrate that vaginal ECs orchestrate an innate response to C. albicans via NF-κB and MAPK signaling pathways. However, unlike in oral ECs, the first MAPK response, defined by c-Jun transcription factor acti…
P38 MAP Kinase Signaling Is Required for the Conversion of CD4+CD25− T Cells into iTreg
2008
CD4+CD25+ regulatory T cells (Treg) are important mediators of immune tolerance. A subset of Treg can be generated in the periphery by TGF-beta dependent conversion of conventional CD4+CD25− T cells into induced Treg (iTreg). In chronic viral infection or malignancy, such induced iTreg, which limit the depletion of aberrant or infected cells, may be of pathogenic relevance. To identify potential targets for therapeutic intervention, we investigated the TGF-beta signaling in Treg. In contrast to conventional CD4+ T cells, Treg exhibited marked activation of the p38 MAP kinase pathway. Inhibition of p38 MAP kinase activity prevented the TGF-beta-dependent conversion of CD4+CD25− T cells into …