Session Title: Systemic Sclerosis, Fibrosing Syndromes and Raynaud's I
Session Type: Abstract Submissions (ACR)
Background/Purpose: Endothelin-1 (ET-1) has been shown to activate myofibroblasts and to enhance the synthesis of extracellular matrix proteins (ECM), such as collagen type I (COL-1) and fibronectin (FN), leading to tissue fibrosis in systemic sclerosis (SSc) progression (1, 2). Macitentan is a new molecule able to antagonize ET receptors. in plasma, besides macitentan, a circulating pharmacologically active metabolite (ACT-132577) has been identifyed (3, 4). We investigated the effects of macitentan and ACT-132577 on myofibroblast activation, by evaluating α-smooth musce actin (α-SMA) expression, and COL-1 and FN synthesis together with their gene expression, induced by ET-1 in cultured SSc and normal skin fibroblasts (Fbs). A comparison between the in vitro effects of macitentan, or ACT-132577 or bosentan was carried out.
Methods: Cultured human skin Fbs were obtained from biopsies of clinically involved skin of 6 SSc patients (4 females and 2 males, mean age 64.8±6.9 years) and 4 age-matched healthy subjects (3 females, 1 male) during diagnostic procedures (Dermatological Clinic, University of Genoa) and after signing informed consent. Following serum starvation (18 hrs), cultured human skin Fbs at 3rd culture passage were treated for 48 hrs with ET-1 (100nM), macitentan (concentration range from 1nM to 10μM), or ACT-132577 (concentration range from 10nM to 100µM), or bosentan (10μM) (Actelion Pharmaceuticals) in RPMI 1640 medium at 5% of fetal bovine serum. Cells were also pre-treated (1 hr) with macitentan, or ACT-132577 or bosentan, respectively, before treatment with ET-1 for 48 hrs. Untreated SSc and normal skin Fbs were used as controls. α-SMA expression was investigated by immunofluorescence (IF). COL-1 and FN synthesis and gene expressions were investigated by immunocytochemistry (ICC) and quantitative real time-polymerase chain reaction (qRT-PCR). Statistical analysis was performed by Mann-Whitney non-parametric t test.
Results: Macitentan and ACT-132577, at the concentration of 10µM, contrasted the increase in α-SMA expression induced by ET-1 in cultured human SSc skin Fbs, displaying same effects already showed by bosentan. Macitentan and ACT-132577 significantly antagonized the increase in COL-1 and FN synthesis induced by ET-1 (p<0.01; p<0.01 for macitentan; p<0.05; p<0.05 for ACT-132577 vs. only ET-1-treated cells). Bosentan significantly antagonized the ET-1 mediated increase in COL-1 and FN synthesis in SSc skin Fbs vs. only ET-1-treated cells (p<0.01; p<0.05). Data were confirmed by qRT-PCR. Same results were obtained in normal skin Fbs. Not significant differences were observed between macitentan, ACT-132577 and bosentan effects.
Conclusion: Macitentan and its active metabolite might down regulate the myofibroblast activation and the increased ECM protein synthesis induced by ET-1 in cultured human SSc skin Fbs at the same concentrations of bosentan.
References. 1.Bhattacharyya S. et al. Nat Rev Rheumatol. 2012;8:42-51. 2.Abraham D. et al. Arthrit Res Ther. 2007;9:S2. 3.Iglarz M. et al. J Pharmacol Exp Ther 2008;327:736-45. 4.Sidharta P. et al. Eur J Clin Pharmacol 2011;67:977-84.
BMS, Sanofi and Actelion,
P. P. Tavilla,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effects-of-macitentan-and-its-active-metabolite-in-modulating-extracellular-matrix-synthesis-in-cultured-human-systemic-sclerosis-and-normal-skin-fibroblasts/