Follicular fluid-derived exosomal LncRNA LIPE-AS1 modulates steroid metabolism and survival of granulosa cells leading to oocyte maturation arrest in polycystic ovary syndrome

OBJECTIVE

Women who are of reproductive age can suffer from polycystic ovary syndrome (PCOS), an endocrine disorder. Anovulatory infertility is mostly caused by aberrant follicular development, which is seen in PCOS patients. Due to the dysfunction of reproductive and endocrine function in PCOS patients, assisted reproduction treatment is one of the main means to obtain clinical pregnancy for PCOS patients. Long non-coding RNA (lncRNA) as a group of functional RNA molecules have been found to participate in the regulation of oocyte function, hormone metabolism, and proliferation and apoptosis of granulosa cells. In this study, we investigated the role of lncRNAs in follicular fluid-derived exosomes and the underlying mechanism of lncRNA LIPE-AS1.

METHODS

We used RNA sequencing to analyze the lncRNA profiles of follicular fluid-derived exosomes in PCOS patients and controls. RT-qPCR was performed to detect the expression levels of these lncRNAs in control (n = 30) and PCOS (n = 30) FF exosome samples. Furthermore, we validated the performance of lncRNA LIPE-AS1 in oocyte maturation by in vitro maturation (IVM) experiments in mouse and steroid metabolism in granulosa cells.

RESULTS

We found 501 lncRNAs were exclusively expressed in the control group and another 273 lncRNAs were found to be specifically expressed in the PCOS group. LncRNA LIPE-AS1, highly expressed in PCOS exosomes, was related to a poor oocyte maturation and embryo development in PCOS patients. Reduced number of MII oocytes were observed in the LIPE-AS1 group by in vitro maturation (IVM) experiments in mouse. LIPE-AS1 was also shown to modulate steroid metabolism and granulosa cell proliferation and apoptosis by LIPE-AS1/miR-4306/LHCGR axis.

CONCLUSION

These findings suggested that the increased expression of LIPE-AS1, facilitated by follicular fluid exosomes, had a significant impact on both oocyte maturation and embryo development. We demonstrated the ceRNA mechanism involving LIPE-AS1, miR-4306, and LHCGR as a regulator of hormone production and metabolism. These findings indicate that LIPE-AS1 is essential in PCOS oocyte maturation and revealed a ceRNA network of LIPE-AS1 and provided new information on abnormal steroid metabolism and oocyte development in PCOS.

A Vortex Method to Disaggregate Platelets for Correct Counting in Pseudothrombocytopenia

Pseudothrombocytopenia (PTCP) refers to the aggregation of platelets in anticoagulant blood in vitro and causes a false lower platelet count (PLT). For the purpose to achieve an accurate PLT, we presented an alternative vortex method to disaggregate platelet clumps and consequently generate a reliable PLT without a second venous puncture for patients. PLT, mean-platelet-volume (MPV), red blood cells (RBCs), hematoglobin (Hb), hematocrit (Hct) and white blood cells (WBCs) were evaluated before and after vortex in 221 specimens with PTCP using vortex method, and the PLT was also compared with 85 specimens disaggregated by citrate method. Twenty control samples were used to investigate mixing effect on complete blood counts in normal samples. One thrombocytopenia specimen was used to evaluate reproducibility of vortex. The mean PLT, MPV, RBCs, Hb, Hct and WBCs of 20 control specimens pre-vortex were 260.7 ± 53.4 × 109/L, 11.65 ± 0.85, 4.87 ± 0.46 × 1012/L, 147.6 ± 13.8 g/L, 45.31 ± 4.04, 6.46 ± 1.41 × 109/L, and results of post-vortex were 252.9 ± 50.2 × 109/L, 11.66 ± 0.92, 4.95 ± 0.48 × 1012/L, 149.1 ± 13.8 g/L, 45.19 ± 4.03, 6.35 ± 1.36 × 109/L respectively. Specimens with platelet clumps using vortex mixer had higher PLT after mixing, the mean pre-vortex PLT was 54.3 ± 35.2 × 109/L, and after vortexing PLT increased to 157.5 ± 58.8 × 109/L (p < 0.05). MPV, RBCs, Hb, Hct and WBCs in 221 specimens were comparable before and after vortex mixing (all p > 0.05). Vortex method might disaggregate platelet clumps sufficiently in most PTCP specimens, and obtain a relatively reliable PLT without the need of a second venous puncture.

Correlation between steroid levels in follicular fluid and hormone synthesis related substances in its exosomes and embryo quality in patients with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is an endocrine and metabolic disorder with various manifestations and complex etiology. Follicular fluid (FF) serves as the complex microenvironment for follicular development. However, the correlation between the concentration of steroid in FF and the pathogenesis of PCOS is still unclear.

METHODS

Twenty steroid levels in FF from ten patients with PCOS and ten women with male-factor infertility undergoing in vitro fertilization were tested by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to explore their possibly correlation with PCOS. Meanwhile, the mRNA levels of core enzymes in steroid synthesis pathway from exosomes of FF were also detected by qPCR.

RESULTS

The estriol (p < 0.01), estradiol (p < 0.05) and prenenolone (p < 0.01) levels in FF of PCOS group were significantly increased, compared to the normal group, and the progesterone levels (p < 0.05) were decreased in PCOS group. Increased mRNA levels of CYP11A, CYP19A and HSD17B2 of exosomes were accompanied by the hormonal changes in FF. Correlation analysis showed that mRNA levels of CYP11A and HSD17B2 were negatively correlated with percent of top-quality embryos and rate of embryos develop to blastocyst.

CONCLUSION

Our results suggest that increased levels of estrogen and pregnenolone in follicular fluid may affect follicle development in PCOS patients, and the mechanism is partially related to HSD17B1, CYP19A1 and CYP11A1 expression change in FF exosomes.