The pathogenesis of ovarian hyperstimulation syndrome: in vivo studies investigating the role of interleukin-1β, interleukin-6, and vascular endothelial growth factor

Abstract

Objective: To evaluate systemic and ovarian changes in levels of interleukin (IL)-1β, IL-6, and vascular endothelial growth factor (VEGF) in response to hCG administration to determine which may be the potential initiator of vascular effects and to identify the main source of the substance; to evaluate serum and follicular fluid levels of these cytokines as markers of ovarian hyperstimulation syndrome (OHSS), and to compare levels of these cytokines under basal conditions in women with normal ovulation and those with polycystic ovary syndrome (PCOS). Design: Prospective controlled study. Setting: In vitro fertilization program at the Instituto Valenciano de Infertilidad, Valencia, Spain. Patient(s): Women undergoing IVF, in whom the first two study objectives were analyzed, and women with normal ovulation and patients with PCOS undergoing retrieval of immature oocytes in natural cycles or cycles stimulated for IUI but cancelled during induction of ovulation, in whom the third study objective was analyzed. Intervention(s): Serum was collected before and after hCG administration, and follicular fluid was collected at ovum pick-up. Main Outcome Measure(s): Serum and follicular fluid levels of IL-1β, IL-6, and VEGF. Result(s): There was a significant increase in serum VEGF levels after hCG administration in patients who were at risk for OHSS compared with those who were not at risk for OHSS. Significantly lower VEGF levels were found in the follicular fluid of patients who were at risk; this decrease was the only useful marker to discriminate between the two groups. Moreover, both groups had similar cytokine production under basal conditions. An increase in serum E 2 occurred coincident with a decrease in IL-1β, IL-6, and VEGF in patients with PCOS. Conclusion(s): Vascular endothelial growth factor seems to be the mediator of hCG on the vascular tree. There was an early systemic increase in VEGF that may have significance in the development of OHSS. A decrease in the follicular fluid VEGF concentration is a valid marker to identify women in whom OHSS will develop. The pattern of cytokine release in patients with PCOS under basal conditions was not different from that in women with normal ovulation.