Concentrations of sRAGE in serum and follicular fluid in assisted reproductive cycles--a preliminary study

To investigate inflammatory processes during ovarian hyperstimulation, we have studied the soluble receptor for advanced glycation end products (sRAGE) levels in sera and follicular fluids of women undergoing in vitro fertilisation (IVF) cycle.

A total of thirty-three women undergoing IVF treatment were recruited, the number of follicles in investigated IVF cycles was 18 +/- 10 (mean +/- SD), oocytes 12 +/- 8, and the clinical pregnancy rate was 42% (14/33). The control group of serum samples was comprised of 35 healthy female blood donors. Sera and follicular fluids were examined for sRAGE levels by enzyme-linked immunosorbent assay (sRAGE ELISA, Quantikine, R&D Systems).

Serum levels of sRAGE in women after ovarian hyperstimulation and induction of ovulation (1039 +/- 493 pg/mL) were significantly lower than in healthy blood donors (1535 +/- 438 pg/mL), p = 0.045. Follicular sRAGE levels (4355 +/- 1100 pg/mL) were significantly higher than serum levels (1039 +/- 493 pg/ml), p < 0.001. Serum sRAGE levels showed significant negative correlation with the number of stimulated follicles (r = -0.71, p = 0.01) and retrieved oocytes (r = -0.54, p = 0.048). Women who successfully conceived after the IVF showed significantly higher sRAGE levels in follicular fluid (4595 +/- 925 pg/mL) compared to women who did not conceive (3986 +/- 806 pg/mL), p = 0.031.

Concentration of sRAGE in follicular fluid is several-fold higher compared to serum and most other biological fluids investigated until this time. It supports the hypothesis that mammalian ovulation can be compared to an inflammatory event. A significant negative correlation of serum sRAGE with the yield of follicles and oocytes, together with the high follicular sRAGE levels, in particular in women who conceive after the IVF, could be explained by the essential outflow of sRAGE to the follicular compartment.