Search results for "Mast Cell"
showing 10 items of 129 documents
Mast cells counteract regulatory T-cell suppression through interleukin-6 and OX40/OX40L axis toward Th17-cell differentiation
2009
Abstract The development of inflammatory diseases implies inactivation of regulatory T (Treg) cells through mechanisms that still are largely unknown. Here we showed that mast cells (MCs), an early source of inflammatory mediators, are able to counteract Treg inhibition over effector T cells. To gain insight into the molecules involved in their interplay, we set up an in vitro system in which all 3 cellular components were put in contact. Reversal of Treg suppression required T cell–derived interleukin-6 (IL-6) and the OX40/OX40L axis. In the presence of activated MCs, concomitant abundance of IL-6 and paucity of Th1/Th2 cytokines skewed Tregs and effector T cells into IL-17–producing T cel…
Activation of Mast Cells by Streptolysin O and Lipopolysaccharide
2005
This chapter provides protocols to measure the reversible permeabilization of mast cells by streptolysin O (SLO) and to follow SLO-induced activation of mast cells by monitoring degranulation, activation of mitogen-activated protein kinases, and production of tumor necrosis factor-alpha. A method that uses SLO to deliver molecules into the cytosol of living cells also is described. Furthermore, we outline a procedure to measure the activation of nuclear factor-kappaB by lipopolysaccharide and ionomycin using transfection of mast cells with reporter genes by electroporation. These protocols should be widely applicable in mast cell research.
The effect of Betanin parenteral pretreatment on Jejunal and pulmonary tissue histological architecture and inflammatory response after Jejunal ische…
2019
Intestinal ischemic-reperfusion (IR) injury has detrimental effects on both local and distant organs in the body. Betanin is known for its antioxidant properties, and it is found mostly in vegetables. Therefore, the aim of the present study was to test the hypothesis that betanin administration prior intestinal IR, may be beneficial in protecting jejunal mucosa and lung parenchyma against IR damage. Male specific pathogen-free Charles River Wistar rats were used (n = 42). Betanin (50 mg/kg) was administered intraperitoneally 30 min before ischemia of the superior mesenteric artery lasting 1 h, followed by 1, 4 and 24 h of reperfusion. Immunohistochemical as well as histomorphometrical analy…
Technical Advance:Soluble OX40 molecule mimics regulatory T cell modulatory activity on Fc{varepsilon}RI-dependent mast cell degranulation.
2011
Tregs play a central role in modulating FcεRI-dependent MC effector functions in the course of the allergic response. Cellular interaction depends on the constitutive expression of OX40 on Tregs and the OX40L counterpart on MCs. Study of OX40L signaling on MCs is hampered by the need of a highly purified molecule, which triggers OX40L specifically. We now report that sOX40 mimics the physiological activity of Treg interaction by binding to activated MCs. When treated with sOX40, activated MCs showed decreased degranulation and Ca++ influx, whereas PLC-γ2 phosphorylation remained unaffected. Once injected into experimental animals, sOX40 not only located within the endothelium but also in pa…
CD4+CD25+ regulatory T cells suppress mast cell degranulation and allergic responses through OX40-OX40L interaction.
2008
T regulatory (Treg) cells play a role in the suppression of immune responses, thus serving to induce tolerance and control autoimmunity. Here, we explored whether Treg cells influence the immediate hypersensitivity response of mast cells (MCs). Treg cells directly inhibited the FcεRI-dependent MC degranulation through cell-cell contact involving OX40-OX40L interactions between Treg cells and MCs, respectively. When activated in the presence of Treg cells, MCs showed increased cyclic adenosine monophosphate (cAMP) concentrations and reduced Ca2+ influx, independently of phospholipase C (PLC)-γ2 or Ca2+ release from intracellular stores. Antagonism of cAMP in MCs reversed the inhibitory effec…
Characterization of a T cell-derived lymphokine that acts synergistically with IL 3 on the growth of murine mast cells and is identical with IL4
1987
Abstract A mast cell-like cell line (SN-1) was established with the aid of growth factor(s) present in the supernatant of a Con A-stimulated L3T4 + T cell line. In analogy to other mast cell lines, IL 3 was identified as a growth factor for SN-1 cells. In addition, a second lymphokine produced by the T cells synergistically enhanced the IL 3-induced growth. This factor, originally termed mast cell growth enhancing factor (MaGEF), could be separated from IL 2, IL 3, a CSF-like activity and was purified to homogeneity. The N-terminal amino acid sequence (8 residues) and the functional properties of this lymphokine proved to be identical with those reported for BSF-1 (IL 4). Unless applied at …
The aryl hydrocarbon receptor modulates acute and late mast cell responses.
2012
Abstract The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor whose activity is modulated by xenobiotics as well as physiological ligands. These compounds may modulate inflammatory responses and contribute to the rising prevalence of allergic diseases observed in industrialized countries. Mast cells (MCs), located within tissues at the boundary of the external environment, represent a potential target of AhR ligands. In this study, we report that murine and human MCs constitutively express AhR, and its activation by the high-affinity ligand 6-formylindolo[3,2-b]carbazole (FICZ) determines a boost in degranulation. On the contrary, repeated exposure to FICZ inhibits…
Tick Salivary Sialostatin L Represses the Initiation of Immune Responses by Targeting IRF4-Dependent Transcription in Murine Mast Cells
2015
Abstract Coevolution 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. In this article, we demonstrate that the tick-derived immunosuppressor sialostatin L restrains IL-9 production by mast cells, whereas 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-1R–deficient mast cells exhibit a strong impairment in IL-9 production, demonstrating the importance of IRF4 and IL-1 in the regulation of the Il9 locus in mast cel…
Transcriptional regulation of the stem cell leukemia gene by PU.1 and Elf-1.
1998
Abstract The SCL gene, also known astal-1, encodes a basic helix-loop-helix transcription factor that is pivotal for the normal development of all hematopoietic lineages. SCL is expressed in committed erythroid, mast, and megakaryocytic cells as well as in hematopoietic stem cells. Nothing is known about the regulation of SCL transcription in mast cells, and in other lineages GATA-1 is the only tissue-specific transcription factor recognized to regulate the SCL gene. We have therefore analyzed the molecular mechanisms underlyingSCL expression in mast cells. In this paper, we demonstrate that SCL promoter 1a was regulated by GATA-1 together with Sp1 and Sp3 in a manner similar to the situati…
The Streptococcal Exotoxin Streptolysin O Activates Mast Cells To Produce Tumor Necrosis Factor Alpha by p38 Mitogen-Activated Protein Kinase- and Pr…
2003
ABSTRACTStreptolysin O (SLO), a major virulence factor of pyogenic streptococci, binds to cholesterol in the membranes of eukaryotic cells and oligomerizes to form large transmembrane pores. While high toxin doses are rapidly cytocidal, low doses are tolerated because a limited number of lesions can be resealed. Here, we report that at sublethal doses, SLO activates primary murine bone marrow-derived mast cells to degranulate and to rapidly induce or enhance the production of several cytokine mRNAs, including tumor necrosis factor alpha (TNF-α). Mast cell-derived TNF-α plays an important protective role in murine models of acute inflammation, and the production of this cytokine was analyzed…