Pakrashi Tarita, Taylor Joelle E, Nelson Ashley, Archer David F, Jacot Terry
Department of Obstetrics and Gynecology, Jones Institute for Reproductive Medicine/Eastern Virginia Medical School, Norfolk, VA, USA
Fertility and IVF Center of Miami, Miami, FL, USA.
Reprod Sci. 2016 Nov;23(11):1536-1541. doi: 10.1177/1933719116645193. Epub 2016 Apr 28.
The levonorgestrel-releasing intrauterine system is considered a highly effective treatment of heavy menstrual bleeding (HMB). While LNG has established effects on the stromal and glandular compartments of the endometrial tissue, its effect on the endometrial endothelial cells has not been investigated. We examined whether LNG regulates fibrinolytic factors, tissue plasminogen activator (tPA), and urokinase plasminogen activator (uPA) secreted by human endometrial endothelial cells (HEECs) and determined the steroid receptor through which LNG exerts its effect on the endothelium.
The HEECs were treated with LNG or progesterone and levels of tPA and plasminogen activator inhibitor 1 (PAI-1) measured. The HEECs were specifically examined for the presence of androgen receptors through Western blot. Levonorgestrel ± flutamide were added to HEECs and the levels of tPA and uPA were examined.
An enzyme-linked immunosorbent assay performed on culture media confirmed a statistically significant decrease in tPA levels in cells treated with LNG (77.80% ± 8.0% of control; n = 5, P < .05 vs control) but not progesterone. The androgen receptor (110 kDa) was detected in HEEC lysates. The decrease in tPA was blocked by the addition of flutamide (101.3% ± 16% of control), a classic nonsteroidal androgen receptor blocker. There was no change in uPA or PAI-1 levels in cells treated with LNG.
Levonorgestrel decreases tPA levels through the androgen receptor in HEECs. Thus, LNG inhibits tPA secretion by the endometrial endothelial cell. This response suggests reduction in HMB with LNG-IUS could reflect an LNG-mediated promotion of hemostasis.
左炔诺孕酮宫内节育系统被认为是治疗月经过多（HMB）的一种高效疗法。虽然左炔诺孕酮对子宫内膜组织的基质和腺体部分有明确作用，但其对子宫内膜内皮细胞的作用尚未得到研究。我们研究了左炔诺孕酮是否调节人子宫内膜内皮细胞（HEECs）分泌的纤溶因子、组织型纤溶酶原激活物（tPA）和尿激酶型纤溶酶原激活物（uPA），并确定了左炔诺孕酮对内皮细胞发挥作用所通过的类固醇受体。
用左炔诺孕酮或孕酮处理HEECs，并测量tPA和纤溶酶原激活物抑制剂1（PAI-1）的水平。通过蛋白质印迹法专门检测HEECs中雄激素受体的存在情况。将左炔诺孕酮±氟他胺添加到HEECs中，并检测tPA和uPA的水平。
对培养基进行的酶联免疫吸附测定证实，用左炔诺孕酮处理的细胞中tPA水平有统计学意义的显著降低（为对照组的77.80%±8.0%；n = 5，与对照组相比P <.05），而孕酮处理组则无此现象。在HEEC裂解物中检测到了雄激素受体（110 kDa）。添加经典的非甾体雄激素受体阻滞剂氟他胺后，tPA的降低被阻断（为对照组的101.3%±16%）。用左炔诺孕酮处理的细胞中uPA或PAI-1水平没有变化。
左炔诺孕酮通过HEECs中的雄激素受体降低tPA水平。因此，左炔诺孕酮抑制子宫内膜内皮细胞分泌tPA。这种反应表明，左炔诺孕酮宫内节育系统减少月经过多可能反映了左炔诺孕酮介导的止血促进作用。
