The Role Of Lin28B In The Placental Development Of Preeclampsia Model Rats

Objective:Preeclampsia is a serious complication of pregnancy.Placenta ischemia may be an initial event,but the molecular mechanism is still unclear.Our previous study found that the expression of Lin28 B in normal pregnancy placental tissue decreased with the increase of gestational age,it is speculated that it may play a role in the formation and development of placenta.Normal pregnancy requires good infiltration of trophoblast cells,which can lead to various diseases such as preeclampsia when poorly infiltrated.This experiment is to construct a rat model of preeclampsia,exploring the expression of Lin28 B in placenta,and clarifing the role of Lin28 B in the pathogenesis of preeclampsia and placental development.Methods:This experiment was divided into 2 parts.Part I:We used a reduced uterine perfusion pressure(RUPP)model in rats.Dividing the pregnancy rats to 2 groups,normal pregnant(NP group)and pregnant with RUPP(RUPP group).On the 14 th days,the ligature were tied around the arterial and venous branches of the abdominal aorta and uterine vascular arcade on the rats in RUPP group.The NP group rats were operated on in a fashion similar to that performed in the RUPP group,but without ligation.The blood pressure were measured on the 13 th and 20 th days of pregnancy.Urine of 24 hours was collected on the 12 th,15th,17 th and 19 th days of pregnancy.On the 20 th days of pregnancy to evaluate the development of fetal rats.Placenta tissues of the rats were collected for assay of mRNA and protein by RT-PCR and Western Blot.Detecting the expression levels of cytokeratin7(CK7)and a-smooth muscle actin(a-SMA)in the triangular region of the placenta.Part II:Dividing the pregnancy rats to 2 groups,RUPP plus overexpression of Lin28B-lentiviral group(Lin28B-LV group)and RUPP plus empty virus group(NC-LV group).On the 14 th days,two groups performed the same operation as RUPP group,in addition to the transfection of Lin28B-lentivirus or empty virus.The rest of the operation is the same as before.Results:(1)Compared with NP rats,the blood pressure change and 24-hour urine proteinincreased significantly in RUPP rats [(33.3±3.3mmHg)vs(3.3±3.2mmHg),(8.82±1.05g).)vs(3.79±0.67 g),P < 0.001].The embryo absorption rate in RUPP rats was69.4%,which was much higher than 3.1% in NP rats.The body weight of fetus was significantly lower than that in NP rats [(4.48±0.53g)VS(3.82±0.29g),P<0.001],but there was no significant difference in placental weight [(0.47±0.07g)vs(0.49±0.12g),P>0.05].The expression of Lin28 B mRNA and protein in the placenta of RUPP rats were lower than that in NP rats [(0.771±0.129)vs(1.000±0.099),(0.153±0.100)vs(0.874±0.484),P<0.001].The results of immunohistochemistry showed that the expression of Lin28 B and CK7 in the RUPP rats were significantly decreased,α-SMA was significantly increased(P<0.05).(2)After overexpressed Lin28 B,the blood pressure change and 24-hour urine protein decreased in Lin28B-LV group compared with NC-LV group [(11.3±5.9 mmHg)vs(27.3±4.5mmHg),(7.00±0.91g)vs(9.82±1.37g),P<0.01,P<0.05].The embryo absorption rate of the NC-LV group was 73%,which was much higher than 38% in Lin28B-LV group.The body weight of fetus was significantly higher than that in NC-LV group [(3.88 ± 0.18g)VS(4.72 ± 0.13g),P<0.001],but there was no significant difference in placental weight [(0.44±0.03g)vs(0.46±0.04g),P>0.05].The expression of Lin28 B mRNA and protein in the placenta of Lin28B-LV rats were higher than that in NC-LV rats [(5.406±1.204)vs(0.840±0.314),(0.635±0.450)vs(0.141±0.103),P<0.001].The results of immunohistochemistry showed that the expression of Lin28 B and CK7 in the Lin28B-LV rats were significantly increased,α-SMA was significantly decreased(P< 0.05).Conclusion:(1)RUPP can successfully establish a rat model of preeclampsia,which is characterized by elevated blood pressure,increased proteinuria,increased number of embryos,and decreased body mass of fetus.(2)The expression of Lin28 B in placenta of preeclampsia rats was significantly decreased and trophoblastic infiltration was insufficient.(3)Overexpressed Lin28 B significantly improved the symptoms and trophoblastic infiltration in preeclampsia rats.