The CYCLOCALYX study: Ovulatory cycle affects circulating compartments of the endothelial glycocalyx in blood

The endothelial glycocalyx (EGX) plays an important role in vascular integrity. Recently, increased levels of EGX components were detected in the circulating blood of healthy pregnant women and were related to the increased tendency to edema formation during gestation. However, the EGX has not yet been systematically studied in non-pregnant women during ovulatory cycles.

Serum levels of EGX components syndecan-1, heparan sulfate, and hyaluronan in healthy women (n = 16) at 3 phases of the ovulatory cycle (early follicular phase, at ovulation, and mid-luteal phase) were compared with a control group of healthy men (n = 10). Using immunofluorescence microscopy in cultured human umbilical vein endothelial cells, the effects of progesterone and estrogen on the EGX were measured.

Syndecan-1 increased from 11.1 ± 2.4 ng/mL at ovulation to 12.6 ± 2.3 ng/mL in mid-luteal phase (P = .031) and of heparan sulfate from 663 ± 35 ng/mL to 782 ± 55 ng/mL (P = .011). In contrast to estrogen, there was a detrimental effect of progesterone on the EGX in HUVECs.

The relationship between the natural menstrual cycle and the EGX as an indicator of vascular permeability may provide a new explanation for premenstrual edema in healthy women. This may be an attendant phenomenon of a regular physiological process, the hormonal downregulation of the vascular barrier during pregnancy.