Effects of selexipag and its active metabolite in contrasting the profibrotic myofibroblast activity in cultured scleroderma skin fibroblasts

Abstract

BackgroundMyofibroblasts contribute to fibrosis through the overproduction of extracellular matrix (ECM) proteins, primarily type I collagen (COL-1) and fibronectin (FN), a process which is mediated in systemic sclerosis (SSc) by the activation of fibrogenic intracellular signaling transduction molecules, including extracellular signal-regulated kinases 1 and 2 (Erk1/2) and protein kinase B (Akt). Selexipag is a prostacyclin receptor agonist synthesized for the treatment of pulmonary arterial hypertension. The study investigated the possibility for selexipag and its active metabolite (ACT-333679) to downregulate the profibrotic activity in primary cultures of SSc fibroblasts/myofibroblasts and the fibrogenic signaling molecules involved.MethodsFibroblasts from skin biopsies obtained with Ethics Committee (EC) approval from patients with SSc, after giving signed informed consent, were cultured until the 3rd culture passage and then either maintained in normal growth medium (untreated cells) or independently treated with different concentrations of selexipag (from 30 μM to 0.3 μM) or ACT-333679 (from 10 μM to 0.1 μM) for 48 h. Protein and gene expressions of α-smooth muscle actin (α-SMA), fibroblast specific protein-1 (S100A4), COL-1, and FN were investigated by western blotting and quantitative real-time PCR. Erk1/2 and Akt phosphorylation was investigated in untreated and ACT-333679-treated cells by western botting.ResultsSelexipag and ACT-333679 significantly reduced protein synthesis and gene expression of α-SMA, S100A4, and COL-1 in cultured SSc fibroblasts/myofibroblasts compared to untreated cells, whereas FN was significantly downregulated at the protein level. Interestingly, ACT-333679 significantly reduced the phosphorylation of Erk1/2 and Akt in cultured SSc fibroblasts/myofibroblasts.ConclusionsSelexipag and mainly its active metabolite ACT-333679 were found for the first time to potentially interfere with the profibrotic activity of cultured SSc fibroblasts/myofibroblasts at least in vitro, possibly through the downregulation of fibrogenic Erk1/2 and Akt signaling molecules.

Promotion of Myofibroblast Differentiation and Tissue Fibrosis by the Leukotriene B4–Leukotriene B4 Receptor Axis in Systemic Sclerosis

“…Since myofibroblasts have been considered to be a pivotal contributor to the progression of fibrosis in SSc, we aimed to investigate whether the LTB 4 -BLT1 axis has a direct influence on myofibroblast differentiation. In addition to the well-accepted evidence of fibroblast-myofibroblast transitions that take place in a variety of fibrotic processes, including SSc (24,25), recent novel findings have suggested that endothelial-mesenchymal transitions may also act as a mechanism for the generation of activated myofibroblasts in SSc (6). Results of the present study demonstrated that BLT1 was expressed in fibroblasts, including primary human dermal fibroblasts (HDFs), embryonic fibroblast cells (NIH/3T3 cell line), and human fetal lung fibroblast cells (MRC-5 cell line), as well as in human umbilical vein endothelial cells (HUVECs) at both the messenger RNA (mRNA) and protein levels (see Supplementary Figures 2A and B, available on the Arthritis & Rheumatology web site at http://onlin elibr ary.wiley.com/doi/10.1002/art.41119 2/ abstract).…”

Cathepsin S regulates renal fibrosis in mouse models of mild and severe hydronephrosis

“…In the ‘non-inhibitor’ groups, the collagen-I and FN levels in the M group were insignificantly higher compared with the N group, whereas significant ECM deposition was observed in the S group. As important components of ECM, collagen-I and FN are often used to indicate the severity of fibrosis (33). In the non-inhibitor groups, ECM deposition did not change significantly in the M group but increased significantly in the S group.…”

<p>Management of digital ulcers in systemic sclerosis</p>

“…Selexipag, an oral selective IP prostacyclin-receptor agonist, has demonstrated positive effects on pulmonary arterial hypertension (PAH) in both patients with and without connective tissue disease, 28,29 and may have direct activity on SSc patients' fibroblasts. 30 Recently, selexipag was tested in an RCT of 74 patients with SSc, and no significant differences were identified on Raynaud's phenomenon number or duration of attacks. At baseline, DUs were present in eight and three patients in the placebo and selexipag groups, respectively.…”