TGF-β1 is a negative regulator of lymphatic regeneration during wound repair

NW Clavin, T Avraham, J Fernandez… - American Journal …, 2008 - journals.physiology.org
NW Clavin, T Avraham, J Fernandez, SV Daluvoy, MA Soares, A Chaudhry, BJ Mehrara
American Journal of Physiology-Heart and Circulatory Physiology, 2008journals.physiology.org
Although clinical studies have identified scarring/fibrosis as significant risk factors for
lymphedema, the mechanisms by which lymphatic repair is impaired remain unknown.
Transforming growth factor-β1 (TGF-β1) is a critical regulator of tissue fibrosis/scarring and
may therefore also play a role in the regulation of lymphatic regeneration. The purpose of
this study was therefore to assess the role of TGF-β1 on scarring/fibrosis and lymphatic
regeneration in a mouse tail model. Acute lymphedema was induced in mouse tails by full …
Although clinical studies have identified scarring/fibrosis as significant risk factors for lymphedema, the mechanisms by which lymphatic repair is impaired remain unknown. Transforming growth factor -β1 (TGF-β1) is a critical regulator of tissue fibrosis/scarring and may therefore also play a role in the regulation of lymphatic regeneration. The purpose of this study was therefore to assess the role of TGF-β1 on scarring/fibrosis and lymphatic regeneration in a mouse tail model. Acute lymphedema was induced in mouse tails by full-thickness skin excision and lymphatic ligation. TGF-β1 expression and scarring were modulated by repairing the wounds with or without a topical collagen gel. Lymphatic function and histological analyses were performed at various time points. Finally, the effects of TGF-β1 on lymphatic endothelial cells (LECs) in vitro were evaluated. As a result, the wound repair with collagen gel significantly reduced the expression of TGF-β1, decreased scarring/fibrosis, and significantly accelerated lymphatic regeneration. The addition of recombinant TGF-β1 to the collagen gel negated these effects. The improved lymphatic regeneration secondary to TGF-β1 inhibition was associated with increased infiltration and proliferation of LECs and macrophages. TGF-β1 caused a dose-dependent significant decrease in cellular proliferation and tubule formation of isolated LECs without changes in the expression of VEGF-C/D. Finally, the increased expression of TGF-β1 during wound repair resulted in lymphatic fibrosis and the coexpression of α-smooth muscle actin and lymphatic vessel endothelial receptor-1 in regenerated lymphatics. In conclusion, the inhibition of TGF-β1 expression significantly accelerates lymphatic regeneration during wound healing. An increased TGF-β1 expression inhibits LEC proliferation and function and promotes lymphatic fibrosis. These findings imply that the clinical interventions that diminish TGF-β1 expression may be useful in promoting more rapid lymphatic regeneration.
American Physiological Society