Regulation of proteoglycan synthesis by leukotriene D4 and epidermal growth factor in bronchial smooth muscle cells

Extracellular matrix (ECM) expansion contributes to airway remodeling in asthma. This study examines the effect of leukotriene D4 (LTD4), combined with epidermal growth factor (EGF), on proteoglycan synthesis by cultured human bronchial smooth muscle cells (BSMCs). LTD4 plus EGF stimulated proliferation of BSMCs with increased versican synthesis. Further, versican mRNA splice variants, V0 and V1, were differently regulated in BSMCs by LTD4 plus EGF. Synthesis of [S-35]-methionine labeled versican V0, as a percentage of total versican, was doubled. This upregulation was confirmed by Western analysis. Synthetic changes were paralleled by alterations in versican V0 mRNA. The effects of LTD4 and EGF on proteoglycan synthesis were inhibited by montelukast. Similar upregulation of versican V0 was observed in arterial smooth muscle cells (ASMCs) stimulated with LTD4 plus EGF as measured by western and reverse transcriptase-polymerase chain reaction analyses. Changes in ECM in the asthmatic airway may parallel those in atherosclerotic lesions where proliferating ASMCs synthesize a versican-rich expanded ECM. Inhibition of these processes could lead to reduced tissue expansion in the early phases of asthma progression.