Fibronectin 1 is a novel biomarker of obstetric antiphospholipid syndrome

Objective To investigate novel biomarkers and the mechanism of obstetric antiphospholipid syndrome (OAPS). Methods HTR8/SVneo cells line were treated with plasma from OAPS (OAPS group) and healthy (NC group) pregnant women, respectively. The changes induced by plasma treatment at the transcriptome level were examined by RNA sequencing of the cells. Results were analyzed with bioinformatics tools to elucidate the potential biomarkers. Reverse-transcription quantitative polymerase chain reaction (RT-qPCR), western blotting, hematoxylin and eosin (HE), immunohistochemistry (IHC), and immunofluorescence (IF) were used for subsequent validation. Results Bioinformatic analysis revealed the expression of Fibronectin 1 (FN1) was significantly increased in OAPS group. On analyzing molecular function, OAPS plasma exposure mainly affected the expression of the genes related to extracellular matrix (ECM) structural constituent. Compared to the NC group, differently expressed genes were mainly annotated to the collagen-containing ECM matrix and the ECM organization. In OAPS group, the protein expression of FN1 was also increased in blood ( p <0 .05). The mRNA and protein expression of FN1 in placenta tissue were increased ( p <0 .05) in OAPS group. Massive degeneration and atrophy can be seen in placental villi, with a significant reduction or disappearance of syncytiotrophoblasts and excessive fibrinoid deposition in the villous stroma of OAPS placenta. Both IHC and IF results showed the staining area and intensity of FN1 in the placental villi and stroma were significantly higher in OAPS group. Conclusions FN1 may play a potential role in the pathogenic mechanisms of OAPS. ### Competing Interest Statement The authors have declared no competing interest.