The plant defensins PaDef and γ-thionin inhibit the endothelial cell response to VEGF.

Angiogenesis is involved in wound repair and tissue maintenance but is associated with diverse diseases. Pro-angiogenic factors such as vascular endothelial growth factor (VEGF) regulate this process. Therefore, searching for treatments to inhibit or promote angiogenesis is attractive. Reports from our group showed that plant antimicrobial peptides (PAPs) PaDef from avocado and γ-thionin from habanero pepper are cytotoxic on cancer cells. However, their functions as angiogenic regulators are unknown. In this work, we evaluate the effect of PaDef and γ-thionin on the angiogenic processes of two different endothelial cell lines: bovine endothelial cells (BUVEC) and the human endothelial cell line EA.hy926. The results showed that VEGF (10 ng/mL) stimulated the BUVEC (40 ± 7 %) and EA.hy926 cell proliferation (30 ± 9 %); however, peptides (5-500 ng/mL) reverted this effect. Besides, VEGF increased the migration of BUVEC (20 ± 8 %) and EA.hy926 cells (50 ± 6 %), but both PAPs (5 ng/mL) inhibited the VEGF stimulus (100 %). Furthermore, DMOG 50 μM (an inhibitor of HIF-hydroxylase) was used in BUVEC and EA.hy926 cells to determine the effect of hypoxia on VEGF and peptide activities. The DMOG reverted the inhibitory action of both peptides (100 %), indicating that peptides act through a HIF-independent pathway. Also, the PAPs do not affect the tube formation but decrease it in EA.hy926 cells stimulated with VEGF (100 %). Additionally, docking assays showed a possible interaction between PAPs and the VEGF receptor. These results suggest that plant defensins PaDef and γ-thionin are potential angiogenic modulators of the VEGF activity on endothelial cells.