Transforming growth factor β1-induced NADPH Oxidase-4 expression and fibrotic response in conjunctival fibroblasts
Methods: The mRNA expression of Nox isoforms in rabbit conjunctival fibroblasts was measured by real-time PCR. The production of hydrogen peroxide (H2O2) and total collagen by these cells was measured by Amplex Red assay and Picro-Sirius red assay, respectively. Nox4 was knocked down by adenovirus-mediated siRNA targeting Nox4 (Adv-Nox4i).
Results: We describe for the first time that conjunctival fibroblasts express mRNA encoding for Nox2, Nox3, Nox4, and Nox5. TGFβ1 was found to induce Nox4 mRNA expression and total collagen release by these cells (P < 0.05; n = 4), and both responses are blocked by Smad3 inhibitor SIS3. Suppressing Nox4 gene transcription with Adv-Nox4i completely attenuated TGFβ1-stimulated H2O2 release and collagen production by conjunctival fibroblasts (P < 0.05; n = 4-6). Similarly, curcumin also inhibited TGFβ1-induced Smad3 phosphorylation, Nox4-derived H2O2 production, and total collagen synthesis by conjunctival fibroblasts (P < 0.05; n = 4-6).
Conclusions: The present study suggests that TGFβ1-mediated production of collagen by conjunctival fibroblasts involves Nox4-derived H2O2 pathway and this effect of Nox4 is abrogated by curcumin. This mechanism might be exploited to prevent fibrotic scarring after surgeries and chemical burn injuries in the eye.
Publication titleInvestigative Ophthalmology & Visual Science
Department/SchoolMenzies Institute for Medical Research
PublisherAssociation for Research in Vision and Ophthalmology
Place of publicationUnited States
Rights statementCopyright 2017 The Authors. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. https://creativecommons.org/licenses/by-nc-nd/4.0/