Effect and Mechanism of Vitamin D on Inflammatory Factors and Neutrophil Activity in Preterm Placenta of Rats Induced by LPS.

To investigate the impact mechanisms of vitamin D on inflammatory factors and neutrophil activity in preterm pregnant rats. 24 pregnant rats were selected as the research objects and randomly divided into control group, LPS group and LPS + VD group, with 8 rats in each group. On the second day of pregnancy, the LPS + VD group was injected intraperitoneally with 50 mg/L vitamin D30.2 mL, and the LPS group and the control group were injected with the same amount of 0.9% NaCl twice a day. On the seventh day of pregnancy, the LPS group and the LPS + VD group were injected with 0.2 mL LPS into the tail vein to establish a preterm labor model induced by infection. The control group was injected with the same amount of physiological saline into the tail vein. Placental tissues from rats in the LPS + VD group and the LPS group were collected, and the expression levels of inflammatory factors TGF-β1, TNF-α, and VDBP were detected by immunohistochemistry. At the same time, serum IL-2 concentration was measured by ELISA and radioimmunoassay, the activity of neutrophils was evaluated by flow cytometry, and the expression of Hippo-YAP signaling pathway protein was detected by Western blot. Compared with the control group, the content of TNF-α, VDBP, and TGF-β1 in placenta in LPS group were higher than that in the control group (P < 5); Compared with the LPS group, the contents of TNF-α, BP and TGF-β1 in the LPS+VD group were significantly reduced,(P < 0.05); Compared with the control group, the serum IL-2 concentration in the LPS group was significantly higher than that in the control group (P < 0.05); Compared with the LPS group, the serum IL-2 concentration in the LPS + VD group decreased significantly (P < 0.05); Compared with the control group, the neutrophil ratio and absolute neutrophil value in the LPS group were higher than those in the control group (P < 0.05); Compared with the LPS group, the neutrophil ratio and absolute value of neutrophils decreased (P < 0.05); compared with the control group, the expression levels of YAP and P-YAP protein in the LPS group increased (P < 0.05); compared with the LPS group, the expression levels of YAP and P-YAP protein in the LPS + VD group decreased (P < 0.05). Vitamin D can improve the immune status of preterm pregnant mice by inhibiting the expression of placental inflammatory factors.