Characterization of Cord-Blood-Derived Human Mast Cells Cultured in the Presence of Steel Factor and lnterleukin-6

118

114

The plasminogen activator inhibitor type 1 (PAI-1) has an essential role in tissue remodeling. The PAI-1 gene was induced by a combination of phorbol ester and calcium ionophore at the highest level among the inducible human mast cell genes that we have analyzed on a DNA microarray. PAI-1 was secreted by both a human mast cell line (HMC)-1 and primary cultured human mast cells upon stimulation, whereas PAI-1 was undetectable in either group of unstimulated cells. The secretion of PAI-1 was due to de novo synthesis of PAI-1 rather than secretion of preformed PAI-1. The functional significance of PAI-1 secretion was demonstrated by complete inhibition of tissue-type plasminogen activator activity with supernatants of stimulated HMC-1 cells. Furthermore, we were able to regulate PAI-1 gene expression in HMC-1 cells by known therapeutic agents. High-dose (1 μM) dexamethasone induced PAI-1 mRNA expression. Cyclosporin down-regulated the expression of the PAI-1 gene. Cycloheximide abrogated PAI-1 mRNA expression, suggesting that transcription of the PAI-1 gene requires de novo synthesis of early gene products, including transcription factors. Finally, we demonstrated PAI-1 in lung mast cells from a patient with asthmatic attack by double-immunofluorescence study. This is the first report demonstrating that activated human mast cells release a striking amount of functionally active PAI-1. These results suggest that PAI-1 could play an important role in airway remodeling of asthma, and inhibition of PAI-1 activity could represent a novel therapeutic approach in the management of airway remodeling.

Section: Cellsmentioning

confidence: 99%

Section: Cellsmentioning

confidence: 99%

Production of Plasminogen Activator Inhibitor-1 by Human Mast Cells and Its Possible Role in Asthma

Cho¹,

Tam²,

Demissie-Sanders³

et al. 2000

118

114

“…The presence of SCF alone is sufficient to direct human hematopoietic progenitors to become MC in vitro (3)(4)(5)(6). SCF is the most potent promoter of MC survival and priming, and also induces their activation (7,8).…”

mentioning

confidence: 99%

Suppression of Normal and Malignant Kit Signaling by a Bispecific Antibody Linking Kit with CD300a

Bachelet

Munitz

Berent-Maoz

et al. 2008

Through its receptor Kit (CD117), stem cell factor (SCF) critically regulates human mast cell (MC) differentiation, survival, priming, and activation. The dominance of SCF in setting these parameters compels stringent contra-regulation to maintain a balanced MC phenotype. We have synthesized a library of bispecific Ab fragments to examine the effect of linking Kit with CD300a. In this study, we report that CD300a exerts a strong inhibitory effect on Kit-mediated SCF-induced signaling, consequently impairing MC differentiation, survival, and activation in vitro. This effect derives from Kit-mediated tyrosine phosphorylation of CD300a and recruitment of the SHIP-1 but not of SH2-containing protein phosphatase 1. CD300a inhibits the constitutive activation of the human leukemic HMC-1 cells but not their survival. Finally, CD300a abrogates the allergic reaction induced by SCF in a murine model of cutaneous anaphylaxis. Our findings highlight CD300a as a novel regulator of Kit in human MC and suggest roles for this receptor as a suppressor of Kit signaling in MC-related disorders.

“…5A) were generated as reported (42). Toluidine blue and tryptase staining confirmed that the purity of the mast cells exceeded 90%.…”

Section: Human Mast Cells Expressed Integrin ␣ Iib ␤ 3 and Mediated Amentioning

confidence: 99%

“…Human cord blood-derived mast cells were generated from CD34 ϩ cord blood cells, as described (42). Mast cells with 90% purity were generated by 8 wk of culture in the medium containing 10% FCS, 100 ng/ml human SCF, and 50 ng/ml human IL-6.…”

Section: Cellsmentioning

confidence: 99%

Integrin αIIbβ3 Induces the Adhesion and Activation of Mast Cells through Interaction with Fibrinogen

Oki

Kitaura

Eto

et al. 2006

Integrin αIIb, a well-known marker of megakaryocyte-platelet lineage, has been recently recognized on hemopoietic progenitors. We now demonstrate that integrin αIIbβ3 is highly expressed on mouse and human mast cells including mouse bone marrow-derived mast cells, peritoneal mast cells, and human cord blood-derived mast cells, and that its binding to extracellular matrix proteins leads to enhancement of biological functions of mast cells in concert with various stimuli. With exposure to various stimuli, including cross-linking of FcεRI and stem cell factor, mast cells adhered to extracellular matrix proteins such as fibrinogen and von Willebrand factor in an integrin αIIbβ3-dependent manner. In addition, the binding of mast cells to fibrinogen enhanced proliferation, cytokine production, and migration and induced uptake of soluble fibrinogen in response to stem cell factor stimulation, implicating integrin αIIbβ3 in a variety of mast cell functions. In conclusion, mouse and human mast cells express functional integrin αIIbβ3.