Taken together, these results indicate that cyclophosphamide improves Fli1 deficiency-dependent vascular changes by normalizing the expression of angiogenesis- and vasculogenesis-related molecules and endothelial Fli1, which may help to explain the beneficial effect of cyclophosphamide on SSc vasculopathy.
Taken together, these results indicate that CXCL13 expression is upregulated by Fli1 deficiency in macrophages, potentially contributing to the development of tissue fibrosis, vasculopathy and immune activation in SSc, especially ILD and digital ulcers.
These results indicate that Fli1 deficiency promotes migration, proliferation and cell survival, while abating tube formation of endothelial cells, suggesting that Fli1 deficiency is potentially attributable to the development of both proliferative obliterative vasculopathy (occlusion of arterioles and small arteries) and destructive vasculopathy (loss of small vessels) characteristic of SSc vasculopathy.
Therefore, we investigated a potential impact of glycyrrhizin on the key pathological manifestations of SSc, including inflammation, vasculopathy, and tissue fibrosis, with bleomycin-treated mice mimicking the fibrotic and inflammatory components of SSc and endothelial cell-specific Fli1-knockout mice recapitulating SSc vasculopathy.
Fli1 Deficiency Induces CXCL6 Expression in Dermal Fibroblasts and Endothelial Cells, Contributing to the Development of Fibrosis and Vasculopathy in Systemic Sclerosis.
Collectively, these results suggest that decreased serum LIF levels may be associated with vasculopathy in SSc and that Fli1 deficiency may contribute to the inhibition of LIF-dependent biological effects on SSc endothelial cells by suppressing the expression of LIF, LIF receptor, and gp130.
Klf5(+/-) ;Fli1(+/-) mice develop immune activation, vasculopathy and tissue fibrosis in this sequence, eventually resulting in the development of dermal fibrosis, interstitial lung disease and pulmonary vascular involvement resembling those of SSc.
Collectively, these results suggest that endothelial CTSL up-regulation partially due to Fli1 deficiency may contribute to the development of vasculopathy, while the decrease in dermal CTSL expression is likely associated with dermal fibrosis in SSc.
The vascular fragility of Fli-1 ECKO mice was improved by bosentan through the normalization of Fli-1 protein levels and activity in endothelial cells, which may explain, in part, the mechanism underlying the beneficial effects of endothelin receptor blockade on SSc vasculopathy.
Notably, mice with double heterozygous deficiency of Klf5 and Fli1 mimicking the epigenetic phenotype of SSc skin spontaneously recapitulate all the three features of SSc, including fibrosis and vasculopathy of the skin and lung, B-cell activation and autoantibody production.
Since Fli1 deficiency is deeply related to aberrant angiogenesis in SSc, it is plausible that serum CXCL5 levels inversely reflect the severity of SSc vasculopathy.
Decreased cathepsin V expression due to Fli1 deficiency contributes to the development of dermal fibrosis and proliferative vasculopathy in systemic sclerosis.
Previous studies demonstrated that Fli1 is downregulated in SSc fibroblasts by an epigenetic mechanism and a series of experiments with Fli1-deficient animal models revealed that Fli1 deficiency in fibroblasts and endothelial cells reproduces the histopathologic features of fibrosis and vasculopathy in SSc, respectively.