hPMSC transplantation restoring ovarian function in premature ovarian failure mice is associated with change of Th17/Tc17 and Th17/Treg cell ratios through the PI3K/Akt signal pathway

BACKGROUND: Human placenta-derived mesenchymal stem cell (hPMSC) transplantation has been demonstrated to be an effective way of recovering ovarian function in mice with autoimmune induced premature ovarian failure (POF). But the exact mechanism remains unclear. The goal of the present study is to investigate the role of immune factors (T-helper 17 (Th17), cytotoxic T (Tc17) and regulatory T (Treg) cells) in the recovery of ovarian function and whether the phosphatidylinositol 3-kinase (PI3K)/Akt signal pathway is involved in the regulation. METHODS: The inhibitor of PI3K/Akt was administered to observe its effect on ovarian function recovery and immune regulation. Serum levels of estradiol (E(2)), follicle stimulation hormone (FSH), luteinizing hormone (LH) and anti-Müllerian hormone (AMH)) and anti-Zona pellucida antibody (AZPAb) were measured by ELISA to evaluate ovarian function. The morphological changes of ovaries were observed by HE staining. Apoptosis of granular cells (GCs) was determined by detecting the expression of capase-3. Expression of p-Akt protein was detected by immunohistochemistry and western blot assay in ovarian tissues. The MTT assay was performed to assess GC proliferation. GC apoptosis was performed using flow cytometry analysis. Percentages of Th17, Tc17 and Treg cells were detected by flow cytometry. Expression of interleukin (IL)-17 in serum was measured by ELISA. RESULTS: LY294002 administration decreased serum levels of E(2) and AMH, while the levels of FSH, LH and AZPAb in serum were increased compared with mice in the hPMSC transplantation group. The ovarian morphology presented as atrophy and fibrosis, with functional follicles exhausted. The expression of p-Akt in ovarian tissue was significantly decreased. Also, LY294002 administration significantly decreased proliferation and increased cell apoptosis in GCs, and for immune factors the ratios of Th17/Tc17 and Th17/Treg cells were significantly increased, as well as the serum levels of IL-17. CONCLUSIONS: Our data suggest that the PI3K/Akt signal pathway is involved in the recovery of ovarian function by changing the ratios of Th17/ Tc17 and Th17/Treg cells in POF mice following hPMSC transplantation.