Inhibition of profibrotic microRNA-21 affects platelets and their releasate
Temo Barwari, Seda Eminaga, Ursula Mayr, Ruifang Lu, Paul C. Armstrong, Melissa V. Chan, Mahnaz Sahraei, Marta Fernández-Fuertes, Thomas Moreau, Javier Barallobre-Barreiro, Marc Lynch, Xiaoke Yin, Christian Schulte, Ferheen Baig, Raimund Pechlaner, Sarah R. Langley, Anna Zampetaki, Peter Santer, Martin Weger, Roberto Plasenzotti, Markus Schosserer, Johannes Grillari, Stefan Kiechl, Johann Willeit, Ajay M. Shah, Cedric Ghevaert, Timothy D. Warner, Carlos Fernández-Hernando, Yajaira Suárez, Manuel Mayr
Temo Barwari, Seda Eminaga, Ursula Mayr, Ruifang Lu, Paul C. Armstrong, Melissa V. Chan, Mahnaz Sahraei, Marta Fernández-Fuertes, Thomas Moreau, Javier Barallobre-Barreiro, Marc Lynch, Xiaoke Yin, Christian Schulte, Ferheen Baig, Raimund Pechlaner, Sarah R. Langley, Anna Zampetaki, Peter Santer, Martin Weger, Roberto Plasenzotti, Markus Schosserer, Johannes Grillari, Stefan Kiechl, Johann Willeit, Ajay M. Shah, Cedric Ghevaert, Timothy D. Warner, Carlos Fernández-Hernando, Yajaira Suárez, Manuel Mayr
View: Text | PDF
Research Article Cardiology Cell biology

Inhibition of profibrotic microRNA-21 affects platelets and their releasate

Abstract

Fibrosis is a major contributor to organ disease for which no specific therapy is available. MicroRNA-21 (miR-21) has been implicated in the fibrogenetic response, and inhibitors of miR-21 are currently undergoing clinical trials. Here, we explore how miR-21 inhibition may attenuate fibrosis using a proteomics approach. Transfection of miR-21 mimic or inhibitor in murine cardiac fibroblasts revealed limited effects on extracellular matrix (ECM) protein secretion. Similarly, miR-21–null mouse hearts showed an unaltered ECM composition. Thus, we searched for additional explanations as to how miR-21 might regulate fibrosis. In plasma samples from the community-based Bruneck Study, we found a marked correlation of miR-21 levels with several platelet-derived profibrotic factors, including TGF-β1. Pharmacological miR-21 inhibition with an antagomiR reduced the platelet release of TGF-β1 in mice. Mechanistically, Wiskott-Aldrich syndrome protein, a negative regulator of platelet TGF-β1 secretion, was identified as a direct target of miR-21. miR-21–null mice had lower platelet and leukocyte counts compared with littermate controls but higher megakaryocyte numbers in the bone marrow. Thus, to our knowledge this study reports a previously unrecognized effect of miR-21 inhibition on platelets. The effect of antagomiR-21 treatment on platelet TGF-β1 release, in particular, may contribute to the antifibrotic effects of miR-21 inhibitors.

Authors

Temo Barwari, Seda Eminaga, Ursula Mayr, Ruifang Lu, Paul C. Armstrong, Melissa V. Chan, Mahnaz Sahraei, Marta Fernández-Fuertes, Thomas Moreau, Javier Barallobre-Barreiro, Marc Lynch, Xiaoke Yin, Christian Schulte, Ferheen Baig, Raimund Pechlaner, Sarah R. Langley, Anna Zampetaki, Peter Santer, Martin Weger, Roberto Plasenzotti, Markus Schosserer, Johannes Grillari, Stefan Kiechl, Johann Willeit, Ajay M. Shah, Cedric Ghevaert, Timothy D. Warner, Carlos Fernández-Hernando, Yajaira Suárez, Manuel Mayr

×

Figure 7

miR-21–null mice display lower platelet and leukocyte numbers but higher numbers of megakaryocytes.

Options: View larger image (or click on image) Download as PowerPoint
miR-21–null mice display lower platelet and leukocyte numbers but higher...
(A) Using Hemavet blood cell counting, significantly lower numbers of platelets, lymphocytes, and monocytes were found in miR-21–null mice (n = 6) compared with those in wild-type littermates (n = 10) (Welch’s t test). (B) Immunohistochemical analysis was performed for TGF-β1 (red), PF4 (green), and a nuclear counterstain (DAPI, blue), using femoral bone marrow sections of miR-21–null mice (n = 10). Representative images are shown. (C) Examination of bone marrow sections from miR-21–null mice revealed increased megakaryocyte numbers, as identified based on morphology and PF4 positivity. Statistical comparison was performed using the Mann-Whitney test; n = 6 vs. 10 for littermate control and miR-21–null mice, respectively. Lines and error bars represent median (IQR). (D) qPCR analysis revealed increased expression levels of megakaryocyte-specific genes Itga2b, Pf4, and Ppbp in bone marrow cells isolated from miR-21–null and littermate control mice. Transcript levels of Tgfb1, Was, and Ptprc (CD45) were not affected. Statistical comparisons using Welch’s t test; n = 6 vs. 6. *P < 0.05, **P < 0.01.