Interleukin 15 In The Placenta Alters Trophoblast Behavior And Glucose Uptake Contributing To Gestational Diabetes Mellitus

Background: Interleukin-15(IL-15),a member of the ‘four helix bundle’ cytokine family,has been associated with many inflammatory and metabolic diseases.Abnormal expression of IL-15 has been linked to the occurrence and development of obesity and diabetes.However,there is a paucity of research on the involvement of IL-15 in Gestational Diabetes Mellitus(GDM).This study aims at investigating the role of IL-15 in the pathogenesis of GDM.Methods: We used the RT-PCR and Western Blot to detect the expression of IL-15 in the placenta from different trimester,and used the immunofluorescence to detect the main source of IL-15 in the placenta.We collected the placenta and peripheral blood from pregnant women with GDM group and normal control group,and used the Si Mo A technology to detect the level of IL-15 in peripheral blood;the expression of IL-15 in placenta of the participates was detected by RT-PCR,Western Blot and immunohistochemistry.Then we detected the expression of IL-15 of trophoblasts which cultured in high glucose in vitro by RT-PCR and Western Blot.We performed the CCK-8assay and colony forming assay to determine the effect of IL-15 on trophoblasts proliferation ability.In order to determine the effect of IL-15 on trophoblasts ability of invasion and tube formation,we performed the Transwell invasion assay and tube formation assay.At last,the expression of proteins in JAK/STAT signaling pathway in trophoblasts which influenced by IL-15 were detected by Western Blot.Results: IL-15 was consistently expressed in the placenta throughout pregnancy and dynamically changed with pregnancy progress.Trophoblasts have been identified as the major source of IL-15 in the placenta.Expression of IL-15 was significantly increased in the placenta of GDM and in the trophoblasts cultured with high glucose(HG).In our study,expression of IL-15 in the placenta was positively correlated with blood glucose concentration of 75 g Oral Glucose Tolerance Test(OGTT),and was inversely correlated with weight of newborns.Further investigations in vitro showed that exogenous addition of IL-15 promoted trophoblasts proliferation,improved invasion and tube formation ability by activating the JAK/STAT signaling pathway,which be blocked by JAK inhibitors.Conclusion: Our results demonstrated that IL-15 expression in the placenta was dynamically changing during pregnancy,and it was upregulated in the placenta of GDM patients.Furthermore,IL-15 altered the biological behavior of trophoblasts through JAK/STAT signaling pathway in vitro,and may contributed to the placental pathology of GDM.Our findings provide a new direction for studying the pathophysiological changes of placenta in GDM.Background: Insulin resistance,which influenced by abnormal expression and translocation of glucose transporter(GLUT),is one of the important pathogenesis of Gestational Diabetes Mellitus(GDM).GLUT in placenta is the carrier of glucose transport between mother and fetus.A variety of factors from the mother,placenta,and fetus can change the expression of GLUT and glucose uptake of the trophoblasts,which ultimately cause abnormalities glucose metabolism of maternal and fetus.At present,many pro-inflammatory factors have been shown to participate in the pathogenesis of diabetes and GDM by regulating the expression of GLUT and glucose uptake.It was found that IL-15 expression was increased in the placenta of GDM in our previous studies,and IL-15 has been confirmed to regulate the expression of GLUT and glucose uptake in varies of cells.However,there is a paucity of research on the involvement of IL-15 and trophoblast’GLUT expression and glucose uptake.This study aims at investigating the role of IL-15 in the expression of GLUT and glucose uptake in trophoblast,and provides a new direction for elucidating the insulin resistance of GDM.Methods: We used the RT-PCR to detect the expression of GLUT m RNA of three trophoblast cell lines,which intervened by different concentrations and different time gradients of IL-15.Western Blot was used to detect the expression of GLUT1 and GLUT4 protein in each group of cells.We used the immunofluorescence assay in order to further explore the expression of GLUT1 protein in trophoblasts’ membrane with IL-15.Finally,the 2-NBDG glucose uptake assay was used to evaluate the ability of glucose uptake in the three trophoblast cells intervened by IL-15.Results: The results of RT-PCR showed that the expression of several GLUT m RNA in the three trophoblast cell lines were decreased under the intervened of different concentration gradients of IL-15 and different time gradients of IL-15.The results of Western Blot showed that the expression of GLUT1 and GLUT4 proteins in the three trophoblast cell lines were decreased significantly under the action of IL-15 with different concentration gradients and time gradients.The results of immunofluorescence showed that IL-15 reduce the expression of GLUT1 protein on the cell membrane of the three trophoblast cell lines,which changes dynamically by intervention time of IL-15.At last,IL-15 reduced the glucose uptake of three trophoblast cell lines,which also fluctuated by the treated time.Conclusion: This study found that IL-15 reduced the expression of trophoblast cells GLUT1 and GLUT4 protein,and reduced the translocation of GLUT1,eventually impaired the glucose uptake capacity of trophoblast cells.Impaired of glucose uptake is an important factor promoted insulin resistance.These results indicate that the up-regulated expression of IL-15 in GDM placenta can further affect the expression and translocation of GLUT of trophoblasts,which promotes insulin resistance in the placenta and participates in the development of GDM.