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Abrogation of transforming growth factor-?-induced tissue fibrosis in mice with a global genetic deletion of Nox4.

ABSTRACT: Excessive connective tissue deposition in skin and various internal organs is characteristic of systemic sclerosis (SSc). The profibrotic growth factor TGF-? plays a crucial role in SSc pathogenesis. The expression of NADPH oxidase 4 (NOX4), a critical mediator of oxidative stress, is potently stimulated by TGF-?. Here, we evaluated the effect of NOX4 on the development of TGF-?-induced tissue fibrosis. C57BL6/J control mice and Nox4 knockout mice were implanted subcutaneously with osmotic pumps containing either saline or 2.5?µg TGF-?1. After 28 days, skin and lung samples were isolated for histopathologic analysis, measurement of hydroxyproline content and gene expression analysis. Histopathology of skin and lungs from normal C57BL6/J mice treated with TGF-?1 showed profound dermal fibrosis and peribronchial and diffuse interstitial lung fibrosis. In contrast, TGF-?-treated Nox4 knockout mice showed normal skin and lung histology. Hydroxyproline levels in TGF-?-treated C57BL6/J mice skin and lungs demonstrated significant increases, however, hydroxyproline content of TGF-?-treated Nox4 knockout mice tissues was not changed. Expression of various profibrotic and fibrosis-associated genes was upregulated in skin and lungs of TGF-?1-treated C57BL6/J mice but was not significantly changed in TGF-?1-treated Nox4 knockout mice. The induction of skin and lung tissue fibrosis by TGF-?1 parenteral administration in mice was abrogated by the genetic deletion of Nox4 confirming that NOX4 is an essential mediator of the profibrotic effects of TGF-?. These results suggest Nox4 inhibition as a potential therapeutic target for SSc and other fibroproliferative disorders.

SUBMITTER: Wermuth PJ

PROVIDER: S-EPMC6530913 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Abrogation of transforming growth factor-β-induced tissue fibrosis in mice with a global genetic deletion of Nox4.

Wermuth Peter J PJ Mendoza Fabian A FA Jimenez Sergio A SA

Laboratory investigation; a journal of technical methods and pathology 20181123 4

Excessive connective tissue deposition in skin and various internal organs is characteristic of systemic sclerosis (SSc). The profibrotic growth factor TGF-β plays a crucial role in SSc pathogenesis. The expression of NADPH oxidase 4 (NOX4), a critical mediator of oxidative stress, is potently stimulated by TGF-β. Here, we evaluated the effect of NOX4 on the development of TGF-β-induced tissue fibrosis. C57BL6/J control mice and Nox4 knockout mice were implanted subcutaneously with osmotic pumps ...[more]

PMID: 30470772

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Project description:Background & aimsTransforming growth factor (TGF)-β-activated kinase 1 (TAK1) is activated in different cytokine signaling pathways. Deletion of Tak1 from hepatocytes results in spontaneous development of hepatocellular carcinoma (HCC), liver inflammation, and fibrosis. TGF-β activates TAK1 and Smad signaling, which regulate cell death, proliferation, and carcinogenesis. However, it is not clear whether TGF-β signaling in hepatocytes, via TGF-β receptor-2 (Tgfbr2), promotes HCC and liver fibrosis.MethodsWe generated mice with hepatocyte-specific deletion of Tak1 (Tak1ΔHep), as well as Tak1/Tgfbr2DHep and Tak1/Smad4ΔHep mice. Tak1flox/flox, Tgfbr2ΔHep, and Smad4ΔHep mice were used as controls, respectively. We assessed development of liver injury, inflammation, fibrosis, and HCC. Primary hepatocytes isolated from these mice were used to assess TGF-β-mediated signaling.ResultsLevels of TGF-β, TGF-βR2, and phospho-Smad2/3 were increased in HCCs from Tak1ΔHep mice, which developed liver fibrosis and inflammation by 1 month and HCC by 9 months. However, Tak1/Tgfbr2ΔHep mice did not have this phenotype, and their hepatocytes did not undergo spontaneous cell death or compensatory proliferation. Hepatocytes from Tak1ΔHep mice incubated with TGF-β did not activate p38, c-Jun N-terminal kinase, or nuclear factor-κB; conversely, TGF-β-mediated cell death and phosphorylation of Smad2/3 were increased, compared with control hepatocytes. Blocking the Smad pathway inhibited TGF-β-mediated death of Tak1-/- hepatocytes. Accordingly, disruption of Smad4 reduced the spontaneous liver injury, inflammation, fibrosis, and HCC that develops in Tak1ΔHep mice. Levels of the anti-apoptotic protein Bcl-xL, β-catenin, connective tissue growth factor, and vascular endothelial growth factor were increased in HCC from Tak1ΔHep mice, but not in HCCs from Tak1/Tgfbr2ΔHep mice. Injection of N-nitrosodiethylamine induced HCC formation in wild-type mice, but less in Tgfbr2ΔHep mice.ConclusionsTGF-β promotes development of HCC in Tak1ΔHep mice by inducing hepatocyte apoptosis and compensatory proliferation during early phases of tumorigenesis, and inducing expression of anti-apoptotic, pro-oncogenic, and angiogenic factors during tumor progression.

Project description:BACKGROUND:Adenomyosis is a medical condition defined by the abnormal presence of endometrial tissue within the myometrium, in which fibrosis occurs with new collagen deposition and myofibroblast differentiation. In this study, the effect of several mediators and growth factors on collagen expression was investigated on human endometrial stromal cells (fibroblasts) derived from adenomyotic endometrium. EXPERIMENTAL APPROACH:RT-PCR, Western blot analysis, pharmacological interventions and siRNA interference were applied to primary cultured human endometrial stromal cells (fibroblasts). Immunohistochemistry was used to analyze protein expression in adenomyotic endometrium tissue specimens. RESULTS:Of the tested mediators, transforming growth factor β1 (TGFβ1) and its isoforms were effective to induce collagen and connective tissue growth factor (CTGF) expression. Collagen and CTGF induction by TGFβ1 could be reduced by the inhibitors targeting DNA transcription, protein translation, and Smad2/3 signaling. Interestingly, TGFβ1 induced Smad2/3 phosphorylation and CTGF mRNA expression, but not collagen mRNA expression, suggesting that TGFβ1 mediates collagen expression through CTGF induction and Smad2/3 activation. In parallel, TGFβ1 and CTGF also induced expression of heat shock protein (HSP) 47, a protein required for the synthesis of several types of collagens. However, only CTGF siRNA knockdown, could compromise TGFβ1-induced collagen expression. Finally, the immunohistochemistry revealed vimentin- and α-SMA-positive staining for (myo)fibroblasts, TGFβ1, collagen, and CTGF in the subepithelial stroma region of human adenomyotic endometria. CONCLUSION AND IMPLICATIONS:We reveal here that TGFβ1, collagen, and CTGF are expressed in the stroma of adenomyotic endometria and demonstrate that TGFβ1 can induce collagen production in endometrium-derived fibroblasts through cellular Smad2/3-dependent signaling pathway and CTGF expression, suggesting that endometrial TGFβ may take part in the pathogenesis of adenomyosis and ectopic endometrium may participate in uterine adenomyosis.

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Abrogation of transforming growth factor-?-induced tissue fibrosis in mice with a global genetic deletion of Nox4.

Publications

Abrogation of transforming growth factor-β-induced tissue fibrosis in mice with a global genetic deletion of Nox4.

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