Tacrolimus rescues the signaling and gene expression signature of endothelial ALK1 loss-of-function and improves HHT vascular pathology

• Published in: Human molecular genetics Vol. 26; no. 24; pp. 4786 - 4798
• Main Authors: Ruiz, Santiago, Chandakkar, Pallavi, Zhao, Haitian, Papoin, Julien, Chatterjee, Prodyot K, Christen, Erica, Metz, Christine N, Blanc, Lionel, Campagne, Fabien, Marambaud, Philippe
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 15.12.2017
• Subjects: Activin Receptors, Type II - genetics; Activin Receptors, Type II - metabolism; Animals; Cell Proliferation; Disease Models, Animal; Endothelial Cells - metabolism; Endothelium, Vascular - metabolism; Gene Expression Profiling; Gene Expression Regulation - genetics; Human Umbilical Vein Endothelial Cells - metabolism; Humans; Loss of Function Mutation - genetics; Mice; Mice, Inbred C57BL; Neovascularization, Pathologic - metabolism; Signal Transduction; Smad Proteins - metabolism; Tacrolimus - metabolism; Tacrolimus - pharmacology; Telangiectasia, Hereditary Hemorrhagic - genetics; Telangiectasia, Hereditary Hemorrhagic - metabolism; Transcriptome - genetics; Vascular Endothelial Growth Factor A - metabolism
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/ddx358

Hereditary hemorrhagic telangiectasia (HHT) is a highly debilitating and life-threatening genetic vascular disorder arising from endothelial cell (EC) proliferation and hypervascularization, for which no cure exists. Because HHT is caused by loss-of-function mutations in bone morphogenetic protein 9 (BMP9)-ALK1-Smad1/5/8 signaling, interventions aimed at activating this pathway are of therapeutic value. We interrogated the whole-transcriptome in human umbilical vein ECs (HUVECs) and found that ALK1 signaling inhibition was associated with a specific pro-angiogenic gene expression signature, which included a significant elevation of DLL4 expression. By screening the NIH clinical collections of FDA-approved drugs, we identified tacrolimus (FK-506) as the most potent activator of ALK1 signaling in BMP9-challenged C2C12 reporter cells. In HUVECs, tacrolimus activated Smad1/5/8 and opposed the pro-angiogenic gene expression signature associated with ALK1 loss-of-function, by notably reducing Dll4 expression. In these cells, tacrolimus also inhibited Akt and p38 stimulation by vascular endothelial growth factor, a major driver of angiogenesis. In the BMP9/10-immunodepleted postnatal retina-a mouse model of HHT vascular pathology-tacrolimus activated endothelial Smad1/5/8 and prevented the Dll4 overexpression and hypervascularization associated with this model. Finally, tacrolimus stimulated Smad1/5/8 signaling in C2C12 cells expressing BMP9-unresponsive ALK1 HHT mutants and in HHT patient blood outgrowth ECs. Tacrolimus repurposing has therefore therapeutic potential in HHT.