Objective: To determine if oral contraceptive (OC) usage alters expression of integrins associated with endometrial receptivity.
Design: Immunohistochemical staining intensity for integrins was compared in frozen sections of endometrial tissue specimens obtained from women with normal ovulatory cycles (n = 23; cycle days 20 to 24 based on LH surge) and from those taking oral contraceptives pills (n = 23; cycle days 5 to 27).
Setting: University-based outpatient infertility clinic.
Results: Constitutive integrin expression in the endometrium (alpha 2 beta 1, alpha 3 beta 1, alpha 5 beta 1, alpha 6 beta 1, and alpha 6 beta 4) was similar in OC users and normally cycling individuals, except for an increase in epithelial alpha 3 beta 1 in OC users. Oral contraceptive use was associated with significant alterations in cycle-dependent integrin expression (alpha 1 beta 1, alpha 4 beta 1, and alpha v beta 3). Specifically, we observed increased glandular alpha 4 beta 1, and decreased alpha v beta 3 expression. The P-regulated alpha 1 subunit was present in both groups. Increased stromal alpha v and beta 3 and decreased alpha 3 beta 1 and alpha 6 beta 1 staining was observed in OC users.
Conclusions: Expression of those integrins most closely associated with endometrial receptivity, alpha v beta 3 and alpha 4 beta 1, is altered in the glandular epithelium of women taking OCs. Stromal integrin expression in OC users also differs from that in cycling women. These alterations in epithelial and stromal integrin expression suggest that impaired uterine receptivity is one mechanism whereby OCs exert their contraceptive actions.