Exosomes-mediated transmission of standard bovine viral diarrhea strain OregonC24Va in bovine trophoblast cells.

Bovine viral diarrhoea virus (BVDV) can infect cows on days 30-110 of gestation and crossing the placental barrier, resulting in persistently infected (PI) and causing significant economic losses to dairy farming. Bovine placental trophoblast cells (BTCs) are the major cells in the early chorionic tissue of the placenta and play important roles in placental resistance to viral transmission. In this study, we have confirmed that BTCs is among a groups of cell types those could be infected by BVDV in vivo, and BVDV infection stimulates the autophagic responses in BTCs and promotes the release of exosomes. Meanwhile, the exosomes derived from BTCs can be used by BVDV to spread between placental trophoblast cells, and this mode of transmission cannot be blocked by antibodies against the BVDV E2 protein, whereas the replication and spread of BVDV in BTCs can be blocked by inhibiting autophagy and exosomogenesis. Our study provides a theoretical and practical basis for scientific prediction and intervention of reproductive disorders caused by BVDV infection in cows of different gestation periods from a novel perspective.

CREG1 promotes bovine placental trophoblast cells exosome release by targeting IGF2R and participates in regulating organoid differentiation via exosomes transport.

BACKGROUND: Placental exosomes are a kind of intercellular communication media secreted by placental cells during pregnancy, exosomogenesis and release are regulated by many secretory glycoproteins. CREG1 is a kind of secreted glycoprotein widely expressed in various organs and tissues of the body, which inhibits cell proliferation and enhances cell differentiation. The aim of this study was to explore the role of CREG1 in regulating exosomogenesis during the proliferation and differentiation of placental trophoblast cells in early pregnant dairy cows by targeting IGF2R and participating in regulating organoid differentiation via exosomes transport. METHODS: Molecular biological methods were firstly used to investigate the expression patterns of CREG1, IGF2R and exosomal marker proteins in early placental development of pregnant dairy cows. Subsequently, the effects of CREG1 on the formation and release of bovine placental trophoblast (BTCs) derived exosomes by targeting IGF2R were investigated. Further, the effects of CREG1 on the change of gene expression patterns along with the transport of exosomes to recipient cells and participate in regulating the differentiation of organoids were explored. RESULTS: The expression of CREG1, IGF2R and exosomal marker proteins increased with the increase of pregnancy months during the early evolution of placental trophoblast cells in dairy cows. Overexpression of Creg1 enhanced the genesis and release of exosomes derived from BTCs, while knocking down the expression of Igf2r gene not only inhibited the genesis of exosomes, but also inhibited the genesis and release of exosomes induced by overexpression of CREG1 protein. Interestingly, IGF2R can regulate the expression of CREG1 through reverse secretion. What's more, the occurrence and release of trophoblast-derived exosomes are regulated by CREG1 binding to IGF2R, which subsequently binds to Rab11. CREG1 can not only promote the formation and release of exosomes in donor cells, but also regulate the change of gene expression patterns along with the transport of exosomes to recipient cells and participate in regulating the early development of placenta. CONCLUSIONS: Our study confirmed that CREG1 is involved in the exosomogenesis and release of exosomes during the proliferation and differentiation of placental trophoblast cells in early pregnant dairy cows by targeting IGF2R, and is involved in the regulation of organoid differentiation through exosome transport.

Replication of standard bovine viral diarrhea strain OregonC24Va induces endoplasmic reticulum stress-mediated apoptosis of bovine trophoblast cells.

Bovine viral diarrhea (BVD) is a worldwide infectious disease caused by bovine viral diarrhea virus (BVDV) infection, which invades the placenta, causes abortion, produces immune tolerance and continuously infects calves, and causes huge economic losses to the cattle industry. The endoplasmic reticulum (ER) is an important organelle in cells, which is prone to ER stress after being stimulated by pathogens, thus activating the ER stress-related apoptosis. Studies have confirmed that BVDV can utilize the ER of its host to complete its own proliferation and stimulate ER stress to a certain extent. However, the role of ER stress in BVDV infecting bovine placental trophoblast cells (BTCs) and inducing apoptosis is still unclear. We are using the cytopathic strain of BVDV (OregonC24Va), which can cause apoptosis of BTCs, as a model system to determine how ER stress induced by BVDV affects placental toxicity. We show that OregonC24Va can infect BTCs and proliferate in it. With the proliferation of BVDV in BTCs, ER stress-related apoptosis is triggered. The ER stress inhibitor 4-PBA was used to inhibit the ER stress of BTCs, which not only inhibited the proliferation of BVDV, but also reduced the apoptosis of BTCs. The ER stress activator Tg can activate ER stress-related apoptosis, but the proliferation of BVDV does not change in BTCs. Therefore, BVDV utilizes the UPR of activated ER stress to promote the proliferation of BVDV in the early stage of infection, and activates the ER stress-related apoptosis of BTCs in the later stage with the virus proliferation to promote the cell apoptosis and further spread of the virus. Our research provides a new theoretical basis for exploring the placental infection and vertical transmission of BVDV.