Abrogation of transforming growth factor-β-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-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 containing either saline or 2.5 μg TGF-β1. 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-β1 showed profound dermal fibrosis and peribronchial and diffuse interstitial lung fibrosis. In contrast, TGF-β-treated Nox4 knockout mice showed normal skin and lung histology. Hydroxyproline levels in TGF-β-treated C57BL6/J mice skin and lungs demonstrated significant increases, however, hydroxyproline content of TGF-β-treated Nox4 knockout mice tissues was not changed. Expression of various profibrotic and fibrosis-associated genes was upregulated in skin and lungs of TGF-β1-treated C57BL6/J mice but was not significantly changed in TGF-β1-treated Nox4 knockout mice. The induction of skin and lung tissue fibrosis by TGF-β1 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-β. These results suggest Nox4 inhibition as a potential therapeutic target for SSc and other fibroproliferative disorders.

Emerging cellular and molecular determinants of idiopathic pulmonary fibrosis

“…Although a potentially vicious cycle of TGF-β and ROS interaction exists, where ROS activate TGF-β and TGF-β activates ROS [156][157][158]), TGF-β1 appears to be the most important trigger of mitochondrial (mtROS) production associated with the profibrotic phenotype reprogramming of lung cells [159]. This proposition is further supported by the observation that the deletion of NOX4 abrogates TGF-β1-induced fibrosis in mice [160]. Moreover, TGF-β1 has been reported to activate NOX4-mediated collagen production in myofibroblasts [161], and this signaling pathway is strongly implicated in IPF pathogenesis [162,163].…”

Iguratimod Inhibits Renal Interstitial Fibrosis in Lupus Nephritis

“…TGF-β1 which has been identi ed as the key pro brogenic cytokine could regulate EMT process through multiple signaling pathways [54][55][56], such as Smad and p38 MAPK. Canonical Smad signaling pathway is considered to be the most important pathway in EMT and most of the TGF-β1-induced EMT appears to be dependent on this signaling pathway [36,57].…”

Redefining Interleukin 11 as a regeneration-limiting hepatotoxin

“…Likewise, although hepatocyte-specific Nox4 deletion is protective 26 , mice with global Nox4 deletion are susceptible to AILI 29 . IL11 is critical for myofibroblasts 14–16 , which are also dependent on NOX4 30, 31 . In the current study, we show reduced hepatic JNK activation following IL11 inhibition, which is similar to that seen in livers of mice with hepatocyte-specific Nox4 deletion and steatohepatitis, further suggestive of an IL11-NOX4 relationship 14, 26 .…”