P-345 GM-CSF drives endometrial repair via p-STAT3 mediating angiogenesis
Authors: Liu J , Lin Y , Sun X , Zhang D 
Published: June 2023

Abstract

Study question
Does granulocyte macrophage colony-stimulating factor (GM-CSF) play a role in endometrial angiogenesis and can it be used as a new application for treating endometrial regeneration?

Summary answer
GM-CSF improves endometrial repair via promoting endometrial angiogenesis and may provide a novel insight and therapeutics for endometrial injury.

What is known already
GM-CSF is a cytokine normally expressed in the female reproductive tract and plays key roles in embryo implantation and subsequent development. Our previous study found that intraperitoneally （i.p.）injection of GM-CSF can significantly improve endometrial repair by promoting endometrial glandular cells proliferation and stromal cells migration, increasing the thickness of endometrium and embryo implantation in mice. However, whether GM-CSF is involved in endometrial angiogenesis is unknown.

Study design, size, duration
To observe whether angiogenesis is promoted by GM-CSF, the expression of angiogenic factor CD31 was evaluated after injection of GM-CSF into endometrial injured mice model. The effect of GM-CSF on vascular g regeneration was also explored by zebrafish embryo model of intersegmental vascular injury. Human umbilical vein vascular endothelial cells (HUVECs) were cultured in vitro, and the role of GM-CSF on HUVECs were examined through EdU, Tube formation, Scratch repair and Transwell assays.

Participants/materials, setting, methods
20μl 90% ethanol was used to establish endometrial injured mice model. After modeling, compared with i.p. injection of GM-CSF and saline, observing whether GM-CSF had the effect of repairing angiogenesis of injured endometrium, by evaluating expression of CD31. Real-time PCR, Western Blot were used to verify differentially expressed levels of mRNA and protein. Western Blot was used to confirm protein location. ChIP was used to analyze stat3 regulation of GM-CSF.

Main results and the role of chance
GM-CSF promoted expression of angiogenic factor CD31 in the mice model of endometrial injury. GM-CSF can repair and regenerate the zebrafish embryo model of intersegmental vascular injury caused by Sorafenib. GM-CSF can promote angiogenesis by HUVECs proliferation and migration, and significantly increase the formation of vascular-like network structures In GM-CSF treatment group, the mRNA expression of VEGF, MMP2, Ang1, Ang2 and Tie2 mRNA in HUVECs cells increased significantly; GM-CSF can activate the phosphorylation expression levels of p-FAK, p-Src, p-ERK 1/2, p-STAT3, p-p38 MAPK, pc-Jun, p-CREB, p-Akt, and p-eNOS. And it can increase the expression of downstream VEGF and MMP2 proteins. GM-CSF treatment for 30 min can promote phosphorylation and translocation of STAT3 from cytoplasm to nucleus, thereby regulating the expression of VEGF and MMP2 downstream. While FAK inhibitors (PF573228) and STAT3 knockdown can abrogate GM-CSF effect on HUVECs.

Limitations, reasons for caution
The results at the cellular and animal level can’t be completely mimic human endometrial injury. In future, well-designed clinical trials are needed to investigate the efficacy and safety of GM-CSF for treatment of human endometrial vascular injury.

Wider implications of the findings
GM-CSF can promote the vascular regeneration in mice model of endometrial injury through p-STAT3. Our findings provide new ideas for clinical treatment of endometrial injury.

Trial registration number
Not applicable