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Expression and modulation of asthma-related cytokines by human lung mast cells
Dissertation

Expression and modulation of asthma-related cytokines by human lung mast cells

Mark Christian Glaum
Doctor of Philosophy (Ph.D.), Medical College of Pennsylvania and Hahnemann University
Jun 1999
DOI:
https://doi.org/10.17918/00007437
pdf
Glaum_Mark_19996.38 MB
PDF Access upon request, Email title, URL, or DOI to archives@drexel.edu

Abstract

Microbiology
The human lung mast cell (HLMC) initiates the early phase response (EPR) seen in asthma and is implicated in diverse fibrotic reactions. We hypothesized that HLMC also release cytokines critical to the genesis of the asthmatic late phase response (LPR) as well as asthmatic fibrotic remodeling. We further hypothesized that corticosteroids (CS), the most potent inhibitors of the LPR clinically, inhibited HLMC generation of Th2 cytokines. Either human lung fragments or HLMCs (>90% pure) were incubated for 16 hr at 37° C in media with or without the corticosteroid dexamethasone (Dex, 1 [mu]M). Fragments or cells were washed, then challenged with buffer, the immunologic stimulus anti-IgE (3 [mu]g/ml) or the non-immunologic stimuli phorbol 12-myristate 13-acetate (PMA, 50 ng/ml) or ionophore A23187 (ION, 1 [mu]g/ml). Histamine release was measured at 20 minutes post-challenge. At 2-4 hr post-challenge, mRNA was analyzed by either RNase protection assay (lung fragments) or RT-PCR (cells) using probes/primers for the Th2 cytokines IL-5, IL-13, IL-16 and the fibrogenic cytokine TGF-[beta]. In either lung fragments or HLMC, Dex preincubation abrogated the anti-IgE-induced expression of IL-5 mRNA and IL-13 mRNA and in HLMC, attenuated expression of IL-16. Anti-IgE-challenged HLMC showed little increase in TGF-[beta] mRNA expression, while PMA-challenged cells showed a 10-fold increase. Preincubation of HLMC in Dex failed to influence constitutive expression of TGF-[beta] mRNA. HLMC showed positive intracellular staining for TGF-[beta] and ELISA experiments demonstrated a 110% (+/- 18%) increase in PMA-induced protein release. We conclude that Dex exerts differential effects on HLMC mediator generation. Since Dex inhibits HLMC-derived Th2-type cytokines (LPR mediators) but not histamine release (EPR mediator) or constitutive TGF-[beta] expression, CS may clinically inhibit the LPR, but not the EPR or fibrotic reactions. Efforts to understand culpable mast cell-derived late phase mediators, as well as mechanisms by which steroids differentially modulate HLMC mediators will provide insight into asthma pathogenesis and better understanding of treatment modalities for this disease.

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