Correcting Smad1/5/8, mTOR, and VEGFR2 treats pathology in hereditary hemorrhagic telangiectasia models
Santiago Ruiz, … , Fabien Campagne, Philippe Marambaud
Santiago Ruiz, … , Fabien Campagne, Philippe Marambaud
Published November 5, 2019
Citation Information: J Clin Invest. 2020;130(2):942-957. https://doi.org/10.1172/JCI127425.
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Research Article Cell biology Vascular biology

Correcting Smad1/5/8, mTOR, and VEGFR2 treats pathology in hereditary hemorrhagic telangiectasia models

Abstract

Hereditary hemorrhagic telangiectasia (HHT), a genetic bleeding disorder leading to systemic arteriovenous malformations (AVMs), is caused by loss-of-function mutations in the ALK1/ENG/Smad1/5/8 pathway. Evidence suggests that HHT pathogenesis strongly relies on overactivated PI3K/Akt/mTOR and VEGFR2 pathways in endothelial cells (ECs). In the BMP9/10-immunoblocked (BMP9/10ib) neonatal mouse model of HHT, we report here that the mTOR inhibitor, sirolimus, and the receptor tyrosine kinase inhibitor, nintedanib, could synergistically fully block, but also reversed, retinal AVMs to avert retinal bleeding and anemia. Sirolimus plus nintedanib prevented vascular pathology in the oral mucosa, lungs, and liver of the BMP9/10ib mice, as well as significantly reduced gastrointestinal bleeding and anemia in inducible ALK1-deficient adult mice. Mechanistically, in vivo in BMP9/10ib mouse ECs, sirolimus and nintedanib blocked the overactivation of mTOR and VEGFR2, respectively. Furthermore, we found that sirolimus activated ALK2-mediated Smad1/5/8 signaling in primary ECs — including in HHT patient blood outgrowth ECs — and partially rescued Smad1/5/8 activity in vivo in BMP9/10ib mouse ECs. These data demonstrate that the combined correction of endothelial Smad1/5/8, mTOR, and VEGFR2 pathways opposes HHT pathogenesis. Repurposing of sirolimus plus nintedanib might provide therapeutic benefit in patients with HHT.

Authors

Santiago Ruiz, Haitian Zhao, Pallavi Chandakkar, Julien Papoin, Hyunwoo Choi, Aya Nomura-Kitabayashi, Radhika Patel, Matthew Gillen, Li Diao, Prodyot K. Chatterjee, Mingzhu He, Yousef Al-Abed, Ping Wang, Christine N. Metz, S. Paul Oh, Lionel Blanc, Fabien Campagne, Philippe Marambaud

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Figure 3

Siro + Nin prevents retinal bleeding in tBMP9/10ib mice.

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Siro + Nin prevents retinal bleeding in tBMP9/10ib mice. (A–L) Represent...
(A–L) Representative images showing microbleeds (dotted orange lines in A–C) in retinas stained with fluorescent isolectin B4 (green) and anti-Ter119 antibody (red) from control (CTRL; A and D–F) and tBMP9/10ib mice treated with DMSO (B and G–I) or Siro + Nin (C and J–L), as in Figure 2A. Dotted white lines in B indicate AVMs. Higher magnifications in D–L show the extending deeper retinal plexus (arrowheads marked as “d” and orthogonal view [xz and yz planes] of the stack of images at the level of the dotted lines are shown in D, G, and J). Orthogonal views in D, G, and J show superficial vascular plexus (yellow arrowheads marked as “s”), vascular branches projecting to the outer layer of the retina (white arrows), and microbleeds (asterisks). Focal plane views (E, H, and K) and 3D reconstructions (F, I, and L) identify microbleeds. Scale bars: 500 μm (A–C) and 50 μm (D–L). (M) Scatter plot measuring bleeding areas, expressed as a percentage of the retinal vascular area occupied by extravascular accumulation of RBCs in mice treated as in Figure 2A. Data represent mean ± SEM (n = 6, 4, 4 mice for the CTRL, DMSO, and Siro + Nin groups, respectively); 1-way ANOVA, Tukey’s multiple-comparisons test. (N) Scatter plots measuring AVM number, vein diameter, and vascular plexus density in the retina of P9 pups treated as in Figure 2A. Data represent individual retinas and mean ± SEM (n = 7, 7, and 8 mice for the CTRL, DMSO, and Siro + Nin groups, respectively); AVM number and vein diameter analyses: 1-way ANOVA, Tukey’s multiple-comparisons test; vascular density analysis: Kruskal-Wallis test, post hoc Dunn’s multiple-comparisons test. **P < 0.01; ****P < 0.0001.