The Expression Of FoxO1in Placenta And Omental Adipose Tissue Of Gestational Diabetes Mellitus

Objective:To investigate the expression of FoxO1in term placenta and omental adipose tissue in pregnant women with gestational diabetes mellitus (GDM) and those with normal glucose tolerance (control). The relationship between FoxO1and TNF-a (tumor necrosis factor-a) in cultured trophoblast cells was also investigated.Methods:1. All subjects were recruited from first affiliated hospital of Nanjing Medical University. Samples were collected from the GDM group (n=20) and the control group (n=20). Fasting plasma glucose (FPG) and fasting serum insulin (FIN) were investigated to calculate an insulin resistance index (HOMA-IR). Immunohistochemistry (IHC) was performed to examine the localization of FoxO1protein in the placenta and adipose tissue. Real time PCR and western blot were used to compare the levels of FoxO1and TNF-α gene and protein between the two groups.2. Western blot was used to investigate the expression of FoxO1protein in cultured trophoblast cells (HTR-8/SVneo and BeWo cells) after treatment with TNF-a (0,1,10,20,50and100ng/ml) for24hours. HTR-8/SVneo and BeWo cells were transfected with FoxO1siRNA and control siRNA oligofectamine and the effect was analyzed by real time PCR and western blot. The effect of FoxO1knockdown on TNF-a stimulated expression of pro-inflammatory cytokines IL-6(Interleukin-6) and IL-1β (Interleukin-1β) was also investigated via real time PCR and ELISA (enzyme linked immunosorbent assay). Results:1. The GDM group showed significantly higher FPG, FIN and HOMA-IR compared with control group. FoxO1was expressed in both the placenta and omental adipose tissue. The gene and protein expression of FoxO1and TNF-α was higher in the GDM group than the control group in both tissues. The expression of FoxO1mRNA and protein in the placenta and adipose tissues was positively correlated with TNF-α. The expression of FoxO1protein in the placenta was positively correlated with FIN and HOMA-IR.2. Stimulation of TNF-α gene increased the expression of FoxO1in cultured trophoblast cells. The expression of FoxO1was highest when treated with TNF-α (20ng/ml). Compared with NS siRNA group, the expression of IL-6and IL-1β in the cells and condition medium was higher in NS siRNA+TNF-α group.In addition, the expression of IL-6and IL-1β in the cells and condition medium was lower in FoxO1siRNA+TNF-α group than NS siRNA+TNF-α group, there was a significant difference.Conclusion:1. More IR was observed in GDM women. Overexpression of FoxO1in placenta and omental adipose tissue may be involved in the process of IR in GDM.2. The expression of FoxO1was under the regulation of TNF-α in cultured trophoblast cells. When exposed to TNF-α, the increased expression of FoxO1promoted the release of the cytokines (IL-6and IL-1β), which may play an important role in GDM.