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

Abstract

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.

Regulation of Activin A Expression in Mast Cells and Asthma: Its Effect on the Proliferation of Human Airway Smooth Muscle Cells

“…Exponentially growing HMC-1 cells were maintained in Iscove's medium, 10% FCS supplemented with antibiotics as described (38). The primary cultured human mast cells (PCHMC) were derived from human cord blood CD34 ϩ cells grown in the presence of stem cell factor, IL-6, and IL-10 as described (38).…”

“…Exponentially growing HMC-1 cells were maintained in Iscove's medium, 10% FCS supplemented with antibiotics as described (38). The primary cultured human mast cells (PCHMC) were derived from human cord blood CD34 ϩ cells grown in the presence of stem cell factor, IL-6, and IL-10 as described (38). Briefly, human cord blood CD34 ϩ cells (BioWhittaker, Walkersville, MD) were cultured in culture medium, consisting of RPMI 1640 (Invitrogen, Carlsbad, CA) supplemented with 20% FBS (Sigma-Aldrich, St. Louis, MO), 2 mM L-glutamine, 50 M 2-ME, 100 U/ml penicillin, 100 g/ml streptomycin, 10 g/ml gentamicin, 80 ng/ml stem cell factor, 50 ng/ml IL-6, and 5 ng/ml IL-10.…”

“…Unstimulated cells were used as the resting control for the microarray analysis. BMMC and PCHMC were stimulated by IgE receptor cross-linking as previously described (38).…”

“…The sensitization and challenge procedures were performed as described (38). Briefly, mice were first sensitized by i.p.…”

Remodelamento das vias aéreas inferiores e superiores

“…24,25 Another mediator released by mast cells is the type 1 plasminogen activation inhibitor, which is also associated with remodeling. 26 The role of certain genes is being debated, such as the anchored protein gene containing a disintegrin and a metalloproteinase on domain 33 gene (ADAM 33), which may affect tissue repair processes. 23,27…”