Therapeutic dosages of oral or transdermal estradiol did not modify sCD40L levels in postmenopausal women.

The CD40/CD40L system is considered a crucial modulator of the inflammatory process underlying the progression and complication of atheroma plaques. The soluble fraction of CD40L (sCD40L) is a reliable indicator of the CD40/CD40L system. Our purpose was to investigate whether a therapeutic dose of estradiol, by either the oral or the transdermal route, was associated with changes in circulating levels of sCD40L. Forty-seven women completed a 4-week course of treatment with either oral estradiol valerate (2 mg/day, 20 women) or transdermal estradiol (50 microg/day, 27 women). Serum levels of sCD40L were measured by conventional enzyme-linked immunosorbent assay. Oral, but not transdermal estradiol, modified the lipid profile. Levels of sCD40L, however, remained unchanged compared with baseline. This neutral effect of oral or transdermal estradiol on sCD40L levels further advances our knowledge on the effects of estrogens on mechanisms involved in the progression and complication of atherosclerosis.