Blockade of TGF-β/Smad signaling by the small compound HPH-15 ameliorates experimental skin fibrosis

Abstract

BackgroundTransforming growth factor-β (TGF-β)/Smad signaling is well known to play a critical role in the pathogenesis of systemic sclerosis (SSc). We previously developed an artificial molecule, the histidine-pyridine-histidine ligand derivative HPH-15, which may have an antifibrotic effect. The purpose of the present study was to clarify the effects of this drug in human skin fibroblasts and in a preclinical model of SSc.MethodsThe effects of HPH-15 on expression of extracellular matrix components and TGF-β signaling in human dermal fibroblasts were analyzed. The antifibrotic properties of HPH-15 and its mechanisms were also examined in a bleomycin-induced skin fibrosis mouse model.ResultsHPH-15 suppressed the TGF-β-induced phosphorylation of Smad3 and inhibited the expression of collagen I, fibronectin 1, connective tissue growth factor, and α-smooth muscle actin induced by TGF-β in cultured human skin fibroblasts. In the bleomycin-induced skin fibrosis model, oral administration of HPH-15 protected against the development of skin fibrosis and ameliorated established skin fibrosis. Additionally, HPH-15 suppressed the phosphorylation of Smad3 in various cells, including macrophages in the bleomycin-injected skin. Further, in the treated mice, dermal infiltration of proinflammatory macrophages (CD11b+Ly6Chi) and M2 profibrotic macrophages (CD11b+CD204+ or CD11b+CD206+) was significantly decreased during the early and late stages, respectively. HPH-15 treatment resulted in decreased messenger RNA (mRNA) expression of the M2 macrophage markers arginase 1 and Ym-1 in the skin, whereas it inversely augmented expression of Friend leukemia integration 1 and Krüppel-like factor 5 mRNAs, the transcription factors that repress collagen synthesis. No apparent adverse effects of HPH-15 were found during the treatment.ConclusionsHPH-15 may inhibit skin fibrosis by inhibiting the phosphorylation of Smad3 in dermal fibroblasts and possibly in macrophages. Our results demonstrate several positive qualities of HPH-15, including oral bioavailability, a good safety profile, and therapeutic effectiveness. Thus, this TGF-β/Smad inhibitor is a potential candidate therapeutic for SSc clinical trials.Electronic supplementary materialThe online version of this article (10.1186/s13075-018-1534-y) contains supplementary material, which is available to authorized users.

Total flavone of Abelmoschus manihot suppresses epithelial-mesenchymal transition via interfering transforming growth factor-β1 signaling in Crohn’s disease intestinal fibrosis

“…Blocking TGF-β/Smad signaling has become a hot spot to inhibit or even reverse fibrosis. It has been reported that silencing Smad 2/3 could block Smad signaling and reduce collagen synthesis and proliferation of fibroblasts[ 40 , 41 ]. We silenced the expression of p-Smad2/3 and explored the role of Smad2/3 in TGF-β1-treated IEC-6 cells.…”

LMP1 Up-regulates Calreticulin to Induce Epithelial-mesenchymal Transition via TGF-β/Smad3/NRP1 Pathway in Nasopharyngeal Carcinoma Cells

“…TGF-β-induced EMT is mainly mediated by the SMAD pathway, and activated TβR-I can specifically recognize and bind to Smad2 and Smad3. Smad2/Smad3 plays an important role in the biological effects of TGF-β, as it is the first signaling molecule for TGF-β pathway-mediated activation [29][30] . There are five binding sites in the promoter region of NRP1 for transcription factor SMAD3 have been predicted using bioinformatics software.…”

Inhibition of the Progression of Skin Inflammation, Fibrosis, and Vascular Injury by Blockade of the CX3CL1/CX3CR1 Pathway in Experimental Mouse Models of Systemic Sclerosis

“…Ly6‐C high inflammatory monocytes respond to inflammatory signals and leave the circulation by extravasation, whereas Ly6‐C low monocytes patrol the luminal side of the vasculature. Recent studies have demonstrated that Ly6‐C high inflammatory monocytes are increased in the tissues in mouse models of fibrosis, including lung fibrosis, unilateral ureteral obstruction–induced fibrosis, and bleomycin‐induced skin fibrosis . Depending on the specific cytokines to which they are exposed, tissue Ly6‐C high macrophages down‐regulate Ly‐6C and polarize cells into tissue‐remodeling/profibrotic (M2‐like) macrophages .…”

“…Female C57BL/6 wild‐type mice (CLEA Japan), BALB/c wild‐type mice, and CX 3 CR1 −/− mice (on a BALB/c background) ages 8–10 weeks were used in the experiments. As described in our previous study , we performed 2 different experiments using a bleomycin‐induced skin fibrosis model in C57BL/6 wild‐type mice. In the preventive experiment, bleomycin (150 μg) was injected subcutaneously once daily into the shaved backs of the mice, concurrent with intraperitoneal injection of the neutralizing anti‐mouse CX 3 CL1 mAb or control IgG at a dose of 500 μg twice a week.…”