Objective To investigate the expression of tumor necrosis factor superfamily member 13B (TNFSF13B) in placental trophoblasts of patients with unexplained recurrent miscarriage (URM) and its potential mechanism. Methods Placental trophoblast samples from 25 URM patients (the URM group) and 25 healthy early pregnancy check⁃up females (the HC group) were subjected to genetic transcriptome sequencing. Differentially expressed genes were screened and bioinformatics analysis was performed. The mRNA and protein expressions of TNFSF13B in placental trophoblasts from the URM group and HC group were detected by real⁃time fluorescent quantitative PCR, immunohistochemistry, and Western blot, respectively. Lentiviral vectors for TNFSF13B gene knockdown and overexpression were constructed using lentiviral transduction technology. HTR⁃8 cells were divided into shTNFSF13B group (transfected with TNFSF13B silent lentivirus), shctrl group (transfected with negative control lentivirus), TNFSF13B group (transfected with overexpression lentiviral vector carrying full⁃length TNFSF13B sequence), and Vector group (transfected with empty lentiviral vector). The effect of TNFSF13B gene knockdown and overexpression was verified by real⁃time fluorescent quantitative PCR and Western blot. The effects of TNFSF13B gene knockdown and overexpression on the expressions of matrix metalloproteinase (MMP)2, MMP9, inhibitor of nuclear factor kappa⁃B alpha (IKB⁃α), and phosphorylated IKB⁃α (p⁃IKB⁃α) were detected by Western blot. Cell proliferation, migration, and invasion abilities of HTR⁃8 cells in the shTNFSF13B, shctrl, TNFSF13B, and Vector groups were assessed using cell proliferation assay, EdU fluorescence labeling assay, and Transwell assay, respectively. Results (1) Transcriptome analysis results revealed 417 up⁃regulated genes and 688 down⁃regulated genes in the URM group. Protein⁃protein interaction network analysis suggested that TNFSF13B might be involved in the occurrence and development of URM. (2) Real⁃time fluorescent quantitative PCR, immunohistochemistry, and Western blot results indicated that the mRNA and protein expressions of TNFSF13B, as well as the optical density of TNFSF13B in placental trophoblasts of the URM group, were lower than those in the HC group (P<0.05). (3) The mRNA and protein expressions of TNFSF13B in HTR⁃8 cells were lower in the shTNFSF13B group than in the shctrl group, and higher in the TNFSF13B group than in the Vector group (P<0.05). (4) The cell proliferation, migration, and invasion abilities of HTR⁃8 cells were weakened in the shTNFSF13B group compared with the shctrl group, and enhanced in the TNFSF13B group compared with the Vector group. (5) Western blot analysis results interpreted that the IKB⁃α expression was lower in the TNFSF13B group than in the Vector group, while the expression of p⁃IKB⁃α, MMP9, and MMP2 were higher than those in the Vector group (P<0.05). The IKB⁃α expression was higher in the shTNFSF13B group than in the shctrl group, while the expressions of p⁃IKB⁃α, MMP9, and MMP2 were lower than those in the shctrl group (P<0.05). Conclusion TNFSF13B expression is decreased in placental trophoblasts of URM patients, and its expression is closely related to the proliferation, migration, and invasion abilities of placental trophoblasts. TNFSF13B may up⁃regulate the expressions of MMP2 and MMP9 through the nuclear factor κB signaling pathway, thereby affecting the function of placental trophoblasts and playing an important role in the occurrence of URM.

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