Endocrine Abstracts

Background: Gestational diabetes mellitus (GDM) affects approximately 14% of pregnancies globally, and is associated with endothelial dysfunction, congenital heart defects and the risk of long-term cardiometabolic complications in offspring. Endothelial-to-mesenchymal transition (EndMT), the transdifferentiation process of endothelial into mesenchymal cells, occurs in normal cardiac development. We hypothesise that altered EndMT may explain some vascular complications in GDM; therefore, the impact of a GDM environment on EndMT was assessed using human umbilical vein endothelial cells (HUVECs) to model the fetal endothelium.

Methods: Commercial HUVECs were treated with TGF-β1 or TGF-β2 alone (10 ng/mL) or in combination (+) with IL-1β (10 ng/mL) for 6 days (n = 3-6). Primary HUVECs isolated from non-GDM (n = 6) and GDM pregnancies (n = 5) were characterised using flow cytometry and EndMT was induced using TGF-β2 (10 ng/mL) + IL-1β (10 ng/mL) for 6 days. Endothelial and mesenchymal markers were measured using RT-qPCR and immunocytochemistry and EndMT signalling components were assessed using RT-qPCR.

Results: In commercial HUVECs, TGF-β2+IL-1β were optimal for EndMT induction. Non-GDM and GDM HUVECs co-expressed CD31 and VE-Cadherin (98.57±0.23% and 99.59±0.14%, respectively), confirming their endothelial phenotype. Treatment of primary HUVECs with TGF-β2+IL-1β induced morphological changes, reduced expression of endothelial genes, PECAM1/CD31, VWF and CDH5/VE-Cadherin (P < 0.05), and increased expression of mesenchymal genes, TAGLN (Transgelin) and NT5E (P < 0.05). Similarly, TGF-β2+IL-1β reduced VE-Cadherin (P < 0.01), VWF (P < 0.01) and increased Transgelin protein expression (P < 0.0001) in primary HUVECs. However, no differences were observed between non-GDM and GDM. Expression of TGFB2 and the TGF-β receptor-1 (TGFBR1/ALK5) were lower in GDM HUVECs treated with TGF-β2+IL-1β, compared to non-GDM (P < 0.05).

Conclusions: EndMT can be induced in non-GDM and GDM HUVECs using TGF-β2+IL-1β. In GDM HUVECs, although EndMT was not altered, reduced TGFB2 and TGFBR1 may be linked to other functions of endothelial TGF-β signalling, such as proliferation/migration, and should be investigated further.