Abstract
Hereditary hemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber syndrome, is an autosomal-dominant vascular disease. The clinical manifestations are epistaxis, mucocutaneous and gastrointestinal telangiectases, and arteriovenous malformations in internal organs. Patients show severe epistaxis, and/or gastrointestinal bleeding, both of which notably interfere with their quality of life. There are two predominant types of HHT caused by mutations in endoglin (ENG) and ACVRL1/activin receptor-like kinase 1 (ALK1) genes, named HHT1 and HHT2, respectively. ENG and ALK1 code for proteins involved in the transforming growth factor (TGF)-β1 signaling pathway, and it is widely accepted that HHT pathogenicity results from haploinsufficiency. No cure for HHT has been found, so identification of drugs able to increase the expression of these genes is essential when proposing new therapies. We report the efficacy of tacrolimus (FK506) in increasing ENG and ALK1 expression. The rationale comes from a case report of a patient with HHT who received a liver transplantation after hepatic failure due to a liver arteriovenous malformation. The liver was transplanted, and the immunosuppressor FK506 was used to prevent the rejection. After the first month of FK506 treatment, the internal and external telangiectases, epistaxes, and anemia disappeared. Here, we find that the immunosuppressor FK506 increases the protein and mRNA expression of ENG and ALK1 in cultured endothelial cells and enhances the TGF-β1/ALK1 signaling pathway and endothelial cell functions like tubulogenesis and migration. These results suggest that the mechanism of action of FK506 involves a partial correction of endoglin and ALK1 haploinsufficiency and may therefore be an interesting drug for use in patients with HHT who undergo transplantation.
Footnotes
This work was supported by the Ministerio de Ciencia e Innovacion [Grants SAF2008-01218, SAF2007-61827, and SAF2010-19222]. The therapeutical in vitro assays in HHT were supported by Fundacion Ramón Areces of Spain (Rare and Emergent Diseases) and a Fundacion Ramon Areces fellowship (to V.A.).
Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
doi:10.1124/mol.110.067447.
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ABBREVIATIONS:
- HHT
- hereditary hemorrhagic telangiectasia
- ENG
- endoglin
- ACVRL/ALK1
- activin receptor-like kinase 1
- FKBP12
- FK binding protein 12
- Id1
- inhibitor differentiation 1
- PAI-1
- plasminogen activator inhibitor-1
- TGF-β1
- transforming growth factor β1
- Smad
- similar mother against decapentaplegic
- FK506
- tacrolimus
- RI
- receptor I
- HMEC-1
- human microvascular endothelial cell
- HUVEC
- human umbilical vein endothelial cell
- PBS
- phosphate-buffered saline
- PCR
- polymerase chain reaction
- PAGE
- polyacrylamide gel electrophoresis
- GST
- glutathione transferase
- ChIP
- chromatin immunoprecipitation
- SBE
- similar mother against decapentaplegic-binding element
- VSMC
- vascular smooth muscle cell
- NFAT
- nuclear factor of activated T cells
- BRE
- bone morphogenic protein-responsive element.
- Received July 12, 2010.
- Accepted February 10, 2011.
- Copyright © 2011 The American Society for Pharmacology and Experimental Therapeutics
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