A Pilot Study of Estrogen's Effects on Bronchial Myocyte Adhesion Molecule Expression

We examined the effects of estrogen on tumor necrosis factor α (TNF‐α)‐induced expression of intracellular adhesion molecule (ICAM‐1) and vascular adhesion molecule (VCAM‐1) in cultured human bronchial smooth muscle cells (BSMC). Experiments were performed in triplicate in T‐75 tissue culture flasks containing normal human BSMC. Four experiments were carried out: untreated BSMC cells (control); TNF‐α 1000 U/ml stimulation of BSMC; forskolin 5 μM before TNF‐α stimulation of BSMC; and estradiol 30 μM before TNF‐α stimulation of BSMC. Cyclic adenosine monophosphate was measured by a commercially available radioimmunoassay kit. Cell expression of ICAM‐1 and VCAM‐1 was quantified by flow cytometry. Incubation of cells with TNF‐α 1000 U/ml for 24 hours elicited a 27‐fold increase in basal expression of ICAM‐1 and a 2‐fold increase in VCAM‐1 (p>0.05). Incubation of BSMC with forskolin 5 μM, for 1 hour before TNF‐α, decreased TNF‐α‐induced expression of ICAM‐1 by 62% and VCAM‐1 slightly by 17%. The BSMC incubated with estradiol 30 μM, 1 hour before TNF‐α, decreased TNF‐α‐induced expression of ICAM‐1 by 21%; VCAM‐1 remained unchanged (p>0.05). We found a trend toward inhibition of TNF‐α‐stimulated ICAM‐1 expression in cultured BSMC with pretreatment with estradiol. However, due to large variability within the cell culture model, statistical significance was not reached.