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The adipokine adiponectin has potent anti-fibrotic effects mediated via adenosine monophosphate-activated protein kinase: novel target for fibrosis therapy.

ABSTRACT: Fibrosis in scleroderma is associated with collagen deposition and myofibroblast accumulation. Peroxisome proliferator activated receptor gamma (PPAR-?), a master regulator of adipogenesis, inhibits profibrotic responses induced by transforming growth factor-ß (TGF-?), and its expression is impaired in scleroderma. The roles of adiponectin, a PPAR-? regulated pleiotropic adipokine, in regulating the response of fibroblasts and in mediating the effects of PPAR-? are unknown.Regulation of fibrotic gene expression and TGF-ß signaling by adiponectin and adenosine monophosphate protein-activated (AMP) kinase agonists were examined in normal fibroblasts in monolayer cultures and in three-dimensional skin equivalents. AdipoR1/2 expression on skin fibroblasts was determined by real-time quantitative PCR.Adiponectin, an adipokine directly regulated by PPAR-?, acts as a potent anti-fibrotic signal in normal and scleroderma fibroblasts that abrogates the stimulatory effects of diverse fibrotic stimuli and reduces elevated collagen gene expression in scleroderma fibroblasts. Adiponectin responses are mediated via AMP kinase, a fuel-sensing cellular enzyme that is necessary and sufficient for down-regulation of fibrotic genes by blocking canonical Smad signaling. Moreover, we demonstrate that endogenous adiponectin accounts, at least in part, for the anti-fibrotic effects exerted by ligands of PPAR-?.These findings reveal a novel link between cellular energy metabolism and extracellular matrix homeostasis converging on AMP kinase. Since the levels of adiponectin as well as its receptor are impaired in scleroderma patients with progressive fibrosis, the present results suggest a potential role for defective adiponectin expression or function in progressive fibrogenesis in scleroderma and other chronic fibrosing conditions. Restoring the adiponectin signaling axis in fibroblasts might, therefore, represent a novel pharmacological approach to controlling fibrosis.

SUBMITTER: Fang F

PROVIDER: S-EPMC3580540 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature

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The adipokine adiponectin has potent anti-fibrotic effects mediated via adenosine monophosphate-activated protein kinase: novel target for fibrosis therapy.

Fang Feng F Liu Lei L Yang Yang Y Tamaki Zenshiro Z Wei Jun J Marangoni Roberta G RG Bhattacharyya Swati S Summer Ross S RS Ye Boping B Varga John J

Arthritis research & therapy 20121023 5

<h4>Introduction</h4>Fibrosis in scleroderma is associated with collagen deposition and myofibroblast accumulation. Peroxisome proliferator activated receptor gamma (PPAR-γ), a master regulator of adipogenesis, inhibits profibrotic responses induced by transforming growth factor-ß (TGF-β), and its expression is impaired in scleroderma. The roles of adiponectin, a PPAR-γ regulated pleiotropic adipokine, in regulating the response of fibroblasts and in mediating the effects of PPAR-γ are unknown.< ...[more]

PMID: 23092446

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Project description:Background: Pulmonary fibrosis (PF) is a devastating interstitial lung disease and characterized by an abnormal accumulation of extracellular matrix (ECM). Nintedanib (NDN) and pirfenidone are two approved therapies for PF, but their potential side-effects have been reported. Recently, the use of natural supplements for PF is attracting attention. Alpha-mangostin (α-MG) is an active xanthone-type compound isolated from the nutritious fruit mangosteen. Purpose: In the present study, the potential effect and underlying mechanism of α-MG were evaluated in bleomycin (BLM)-induced PF and activated primary lung fibroblasts (PLFs). Methods: Histopathological changes and collagen deposition were analyzed via hematoxylin-eosin staining and Masson staining, the expression of nicotinamide adenine dinucleotide phosphate oxidase-4 (NOX4) involved in oxidative stress in lung tissues was analyzed by immunochemistry staining. The expressions of α-smooth muscle actin (α-SMA), collagen I (Col I), p-adenosine 5'-monophosphate-activated protein kinase (AMPK)/AMPK, and NOX4 were detected by Western blot, immunofluorescence or RT-PCR, and effects of α-MG on cell viability were detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. Results: In vivo results demonstrated that α-MG treatment (10 mg/kg/day) significantly ameliorated BLM-induced deposition of ECM in lung tissues. Moreover, α-MG could inhibit protein expressions of α-SMA and Col I as well as its mRNA levels. In addition, α-MG also significantly inhibited transforming growth factor-β1/Smad2/3 pathway and regulated the protein expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in lung tissues. In vitro results demonstrated that α-MG significantly increased p-AMPK/AMPK but reduced the protein expression level of α-SMA and Col I as well as NOX4 in activated PLFs. Further study demonstrated that these improvement effects were significantly blocked by compound C. Conclusion: α-MG treatment significantly decreased oxidative stress in lungs partly by activating AMPK mediated signaling pathway in BLM-induced PF and activated PLFs and decreased the deposition of ECM. The present study provides pharmacological evidence to support therapeutic application of α-MG in the treatment of PF.

Project description:OBJECTIVE:Our goal was to determine the mechanism by which mitochondrial oxidative stress impairs collateral growth in the heart. APPROACH AND RESULTS:Rats were treated with rotenone (mitochondrial complex I inhibitor that increases reactive oxygen species production) or sham-treated with vehicle and subjected to repetitive ischemia protocol for 10 days to induce coronary collateral growth. In control rats, repetitive ischemia increased flow to the collateral-dependent zone; however, rotenone treatment prevented this increase suggesting that mitochondrial oxidative stress compromises coronary collateral growth. In addition, rotenone also attenuated mitochondrial complex I activity and led to excessive mitochondrial aggregation. To further understand the mechanistic pathway(s) involved, human coronary artery endothelial cells were treated with 50 ng/mL vascular endothelial growth factor, 1 µmol/L rotenone, and rotenone/vascular endothelial growth factor for 48 hours. Vascular endothelial growth factor induced robust tube formation; however, rotenone completely inhibited this effect (P<0.05 rotenone versus vascular endothelial growth factor treatment). Inhibition of tube formation by rotenone was also associated with significant increase in mitochondrial superoxide generation. Immunoblot analyses of human coronary artery endothelial cells with rotenone treatment showed significant activation of adenosine monophosphate activated kinase (AMPK)-? and inhibition of mammalian target of rapamycin and p70 ribosomal S6 kinase. Activation of AMPK-? suggested impairments in energy production, which was reflected by decrease in O2 consumption and bioenergetic reserve capacity of cultured cells. Knockdown of AMPK-? (siRNA) also preserved tube formation during rotenone, suggesting the negative effects were mediated by the activation of AMPK-?. Conversely, expression of a constitutively active AMPK-? blocked tube formation. CONCLUSIONS:We conclude that activation of AMPK-? during mitochondrial oxidative stress inhibits mammalian target of rapamycin signaling, which impairs phenotypic switching necessary for the growth of blood vessels.

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The adipokine adiponectin has potent anti-fibrotic effects mediated via adenosine monophosphate-activated protein kinase: novel target for fibrosis therapy.

Publications

The adipokine adiponectin has potent anti-fibrotic effects mediated via adenosine monophosphate-activated protein kinase: novel target for fibrosis therapy.

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