Scleroderma fibroblasts suppress angiogenesis via TGF-β/caveolin-1 dependent secretion of pigment epithelium-derived factor

Abstract

ObjectivesSystemic sclerosis (SSc) is characterised by tissue fibrosis and vasculopathy with defective angiogenesis. Transforming growth factor beta (TGF-β) plays a major role in tissue fibrosis, including downregulation of caveolin-1 (Cav-1); however, its role in defective angiogenesis is less clear. Pigment epithelium-derived factor (PEDF), a major antiangiogenic factor, is abundantly secreted by SSc fibroblasts. Here, we investigated the effect of TGF-β and Cav-1 on PEDF expression and the role of PEDF in the ability of SSc fibroblasts to modulate angiogenesis.MethodsPEDF and Cav-1 expression in fibroblasts and endothelial cells were evaluated by means of immunohistochemistry on human and mouse skin biopsies. PEDF and Cav-1 were silenced in cultured SSc and control fibroblasts using lentiviral short-hairpin RNAs. Organotypic fibroblast–endothelial cell co-cultures and matrigel assays were employed to assess angiogenesis.ResultsPEDF is highly expressed in myofibroblasts and reticular fibroblasts with low Cav-1 expression in SSc skin biopsies, and it is induced by TGF-β in vitro. SSc fibroblasts suppress angiogenesis in an organotypic model. This model is reproduced by silencing Cav-1 in normal dermal fibroblasts. Conversely, silencing PEDF in SSc fibroblasts rescues their antiangiogenic phenotype. Consistently, transgenic mice with TGF-β receptor hyperactivation show lower Cav-1 and higher PEDF expression levels in skin biopsies accompanied by reduced blood vessel density.ConclusionsOur data reveal a new pathway by which TGF-β suppresses angiogenesis in SSc, through decreased fibroblast Cav-1 expression and subsequent PEDF secretion. This pathway may present a promising target for new therapeutic interventions in SSc.

Long non-coding RNA HOTAIR drives EZH2-dependent myofibroblast activation in systemic sclerosis through miRNA 34a-dependent activation of NOTCH

“…Previous work has shown that SSc fibroblasts extracted from patient skin and cultured for an extended period still have enhanced Notch signalling and this is important for their profibrotic phenotype in vitro and for progression of tissue fibrosis in animal models 9 10. Evidence presented here shows that HOTAIR is an important epigenetic factor involved in maintaining Notch signalling through enhanced transcription of the receptor.…”

“…In a complementary approach, we set out to induce stable overexpression of HOTAIR (or scrambled RNA) in human dermal fibroblasts immortalised through retroviral induced expression of HTERT as previously described 10. Immortalised dermal fibroblasts were infected with lentiviral particles carrying HOTAIR gene in frame with GFP and puromycin-resistance genes.…”

“…Fibroblasts are the key cellular elements of fibrosis and once explanted from affected tissues they maintain their profibrotic phenotype in vitro, showing increased secretion of collagen and extracellular matrix proteins and higher frequency of alpha-smooth muscle actin (α-SMA) positive cells (myofibroblasts) 4 5. This epigenetic feature has allowed in-vitro studies which have detailed the molecular mechanisms linked to fibrosis including a key role for growth factors like transforming growth factor beta (TGF-β),6–8 platelet-derived growth factor (PDGF)9 10 and Notch signalling 11 12…”

Dynamics of digital ulcers in systemic sclerosis

“…It has been observed that microvascular endothelial dysfunction has as substrate the appearance of anti-endothelial antibodies and, mainly, the presence of anti-intercellular adhesion molecule (ICAM)-1 antibodies (6). Activated endothelial cells release proinflammatory cytokines and connective tissue growth factors, interleukin (IL)-1, IL-4, tumor necrosis factor (TNF)-α, IL-6 and IL-8 transforming growth factor (TGF)-β, which induce aberrant hyperactivated fibroblasts (7)(8)(9)(10)(11). Early endothelial cell involvement in SSc, leads to the destruction of blood capillaries with reduction in microvasculature through vascular repair and defective neoangiogenesis simultaneously with impaired lymphatic circulation followed by exudative accumulation and edema formation.…”

Genetic Regulation of Pigment Epithelium-Derived Factor (PEDF): An Exome-Chip Association Analysis in Chinese Subjects With Type 2 Diabetes

“…a-2-Antiplasmin specifically induces TGFb1 production during the process of fibrosis (38). On the other hand, TGFb1 has been reported to show direct positive regulation (39,40) and indirect negative regulation on the PEDF expression (41), depending on the cell environment and cell type used in the studies. It is possible that SERPINF2 rs2070863 leads to a decreased expression of a-2-antiplasmin and hence a reduction in TGFb1 production, thereby resulting in reduced TGFb1induced PEDF expression.…”