Sulforaphane mitigates muscle fibrosis in mdx mice via Nrf2-mediated inhibition of TGF-β/Smad signaling

Sulforaphane (SFN), an activator of NF-E2-related factor 2 (Nrf2), has been found to have an antifibrotic effect on liver and lung. However, its effects on dystrophic muscle fibrosis remain unknown. This work was undertaken to evaluate the effects of SFN-mediated activation of Nrf2 on dystrophic muscle fibrosis. Male mdx mice (age 3 mo) were treated with SFN by gavage (2 mg/kg body wt per day) for 3 mo. Experimental results demonstrated that SFN remarkably attenuated skeletal and cardiac muscle fibrosis as indicated by reduced Sirius Red staining and immunostaining of the extracellular matrix. Moreover, SFN significantly inhibited the transforming growth factor-β (TGF-β)/Smad signaling pathway and suppressed profibrogenic gene and protein expressions such as those of α-smooth muscle actin (α-SMA), fibronectin, collagen I, plasminogen activator inhibitor-1 (PAI-1), and tissue inhibitor metalloproteinase-1 (TIMP-1) in an Nrf2-dependent manner. Furthermore, SFN significantly decreased the expression of inflammatory cytokines CD45, TNF-α, and IL-6 in mdx mice. In conclusion, these results show that SFN can attenuate dystrophic muscle fibrosis by Nrf2-mediated inhibition of the TGF-β/Smad signaling pathway, which indicates that Nrf2 may represent a new target for dystrophic muscle fibrosis.

Loureirin B inhibits fibroblast proliferation and extracellular matrix deposition in hypertrophic scar via TGF-β/Smad pathway

The ethanolic extract of Resina Draconis (RDEE) has been reported beneficial to normal wound healing yielding more regularly arranged collagen fibres. Loureirin B, a major component in RDEE, has been supposed to be effective on the prevention and treatment of pathological scars. To investigate the therapeutic effects of loureirin B on hypertrophic scar (HS), fibroblasts from human HS and normal skin (NS) were isolated. Results showed that loureirin B dose-dependently downregulated both mRNA and protein levels of type I collagen (ColI), type III collagen (ColIII) and α-smooth muscle actin (α-SMA) in HS fibroblasts. Loureirin B also suppressed fibroblast proliferative activity and redistributed cell cycle, but did not affect cell apoptosis. In vivo rabbit ear scar model, loureirin B significantly improved the arrangement and deposition of collagen fibres, decreased protein levels of ColI, ColIII and α-SMA and suppressed myofibroblast differentiation and scar proliferative activity. In NS fibroblasts, loureirin B effectively inhibited TGF-β1-induced upregulation of ColI, ColIII and α-SMA levels, myofibroblast differentiation and the activation of Smad2 and Smad3. Loureirin B also affected mRNA levels of major MMPs and TIMPs in TGF-β1-stimulated fibroblasts. Taken together, this study demonstrates that loureirin B could downregulate the expression of fibrosis-related molecules by regulating MMPs and TIMPs levels, inhibit scar fibroblast proliferation and suppress TGF-β1-induced fibrosis, during which TGF-β1/Smad2/3 pathway is likely involved. These findings suggest that loureirin B is a potential therapeutic compound for HS treatment.

Epigallocatechin-3-gallate attenuates unilateral ureteral obstruction-induced renal interstitial fibrosis in mice

The severity of tubulointerstitial fibrosis is regarded as an important determinant of renal prognosis. Therapeutic strategies targeting tubulointerstitial fibrosis have been considered to have potential in the treatment of chronic kidney disease. This study aims to evaluate the protective effects of (-)-epigallocatechin-3-gallate (EGCG), a green tea polyphenol, against renal interstitial fibrosis in mice. EGCG was administrated intraperitoneally for 14 days in a mouse model of unilateral ureteral obstruction (UUO). The results of our histological examination showed that EGCG alleviated glomerular and tubular injury and attenuated renal interstitial fibrosis in UUO mice. Furthermore, the inflammatory responses induced by UUO were inhibited, as represented by decreased macrophage infiltration and inflammatory cytokine production. Additionally, the expression of type I and III collagen in the kidney were reduced by EGCG, which indicated an inhibition of extracellular matrix accumulation. EGCG also caused an up-regulation in α-smooth muscle actin expression and a down-regulation in E-cadherin expression, indicating the inhibition of epithelial-to-mesenchymal transition. These changes were found to be in parallel with the decreased level of TGF-β1 and phosphorylated Smad. In conclusion, the present study demonstrates that EGCG could attenuate renal interstitial fibrosis in UUO mice, and this renoprotective effect might be associated with its effects of inflammatory responses alleviation and TGF-β/Smad signaling pathway inhibition.

Pinus densiflora extract protects human skin fibroblasts against UVB-induced photoaging by inhibiting the expression of MMPs and increasing type I procollagen expression

Exposure to ultraviolet (UV) light can cause skin photoaging, which is associated with upregulation of matrix metalloproteinases (MMPs) and downregulation of collagen synthesis. It has been reported that MMPs, especially MMP-1, MMP-3 and MMP-9, decrease the elasticity of the dermis by degrading collagen. In this study, we assessed the effects of Pinus densiflora extract (PDE) on photoaging and investigated its mechanism of action in human skin fibroblast (Hs68) cells after UVB exposure using real-time polymerase chain reaction, Western blot analysis, and enzymatic activity assays. PDE exhibited an antioxidant activity and inhibited elastase activities in vitro. We also found that PDE inhibited UVB-induced cytotoxicity, MMP-1 production and expression of MMP-1, -3 and -9 mRNA in Hs68 cells. In addition, PDE decreased UVB-induced MMP-2 activity and MMP-2 mRNA expression. Moreover, PDE prevented the decrease of type I procollagen mediated by exposure to UVB irradiation, an effect that is linked to the upregulation and downregulation of Smad3 and Smad7, respectively. Another effect of UV irradiation is to stimulate activator protein 1 (AP-1) activity via overexpression of c-Jun/c-Fos, which, in turn, upregulates MMP-1, -3, and -9. In this study, we found that PDE suppressed UV-induced c-Jun and c-Fos mRNA expression. Taken together, these results demonstrate that PDE regulates UVB-induced expression of MMPs and type I procollagen synthesis by inhibiting AP-1 activity and restoring impaired Smad signaling, suggesting that PDE may be useful as an effective anti-photoaging agent.

Grape seed extract attenuates arsenic-induced nephrotoxicity in rats

Oxidative stress is a recognized factor in nephrotoxicity induced by chronic exposure to inorganic arsenic (As). Grape seed extract (GSE) possesses antioxidant properties. The present study was designed to evaluate the beneficial effects of GSE against arsenic-induced renal injury. Healthy, male Sprague-Dawley rats were exposed to As in drinking water (30 ppm) with or without GSE (100 mg/kg) for 12 months. The serum proinflammatory cytokine levels and mRNA expression levels of fibrogenic markers in the renal tissues were evaluated using enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. The protein expression levels of nicotinamide adenine dinucleotide phosphate (NADPH) subunits, transforming growth factor-β1 (TGF-β1) and phosphorylated Smad2/3 (pSmad2/3) were assessed using western blot analysis. The results demonstrated that cotreatment with GSE significantly improved renal function, as demonstrated by the reductions in relative kidney weight (% of body weight) and blood urea nitrogen, and the increase in the creatinine clearance capacity. GSE attenuated the As-induced changes in the serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β and the mRNA levels of TGF-β1, α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) and fibronectin (FN) in renal tissue. Furthermore, administration of GSE markedly reduced As-stimulated reactive oxygen species (ROS) production and Nox activity, as well as the protein expression levels of the NADPH subunits (Nox2, p47phox and Nox4). In addition, GSE cotreatment was correlated with a significant reduction in TGF-β/Smad signaling, as demonstrated by the decreased protein levels of TGF-β1 and pSmad2/3 in renal tissue. This study indicated that GSE may be a useful agent for the prevention of nephrotoxicity induced by chronic exposure to As. GSE may exert its effects through the suppression of Nox and inhibition of TGF-β/Smad signaling activation.