PLATELET-DERIVED GROWTH-FACTOR-BETA MESSENGER-RNA IN HUMAN ALVEOLAR MACROPHAGES IN-VIVO IN ASTHMA

Collagen deposition and myofibroblast proliferation beneath the epithe lial basement membrane in patients with asthma is now increasingly rec ognized, although the molecular pathogenesis remains obscure. We have evaluated messenger ribonucleic acid (mRNA) expression of the profibro tic cytokine, platelet-derived growth factor-beta (PDGF-beta), in alve olar macrophages obtained following fibreoptic bronchoscopy and bronch oalveolar lavage in patients with asthma. Three subject groups were st udied: 1) asthmatics using regular inhaled glucocorticoid medication ( AST(ST) n=9), 2) asthmatics using intermittent inhaled beta(2)-agonist therapy only (AST(BR), n=10); and 3) nonasthmatic control volunteers (n=10). Alveolar macrophage mRNA was extracted and PDGF-beta mRNA quan tified by reverse-transcriptase polymerase chain reaction (PCR) (RT-PC R) and expressed as the ratio to that of a control gene glyceraldehyde -3-phosphate dehydrogenase (GAPDH). There were no significant differen ces in PDGF-beta mRNA expression between the groups, or between all as thmatic (n=19) and control subjects. Furthermore, there was no correla tion between alveolar macrophage PDGF-beta mRNA expression and airway spirometry, or duration of glucocorticoid usage or dose. Thus, in cont rast to other fibrotic lung diseases, we found little evidence of enha nced expression of PDGF-beta mRNA in alveolar macrophages in clinicall y stable bronchial asthma.