ADRENAL-HORMONE REGULATION OF EXTRACELLULAR-MATRIX SYNTHESIS BY TYPE-II CELLS

Previous studies suggested an. association between changes in extracel lular matrix (ECM) and pulmonary epithelial cell growth and differenti ation in lungs of adrenalectomized rats. The role of adrenal hormones to modulate synthesis of cell and ECM proteins by type II epithelial c ells was thus investigated. In cells isolated from lungs of adrenalect omized animals, synthesis of ECM proteins was stimulated to a greater extent than was synthesis of cell proteins. This resulted in increased relative synthesis of matrix components. Conversely, dexamethasone (2 00 nM) treatment in vitro reduced the effects of adrenalectomy and, in control cells, decreased relative ECM synthesis. The magnitude of the se effects depended on time in culture and serum conditions. For examp le, culture of normal cells in serum-free medium mimicked the effects of adrenalectomy, whereas there were no effects of dexamethasone in th e presence of serum. These results indicate a role for adrenal steroid hormones to modulate ECM metabolism by type II pulmonary epithelial c ells and suggest that consequent effects on ECM biological activity ma y modify epithelial cell differentiation or growth.