Reversal of persistent fibrosis in aging by targeting Nox4-Nrf2 redox imbalance.
The incidence and prevalence of pathological fibrosis increase with advancing age, although mechanisms for this association are unclear. We assessed the capacity for repair of lung injury in young (2 months) and aged (18 months) mice. Whereas the severity of fibrosis was not different between these groups, aged mice demonstrated an impaired capacity for fibrosis resolution. Persistent fibrosis in lungs of aged mice was characterized by the accumulation of senescent and apoptosis-resistant myofibroblasts. These cellular phenotypes were sustained by alterations in cellular redox homeostasis resulting from elevated expression of the reactive oxygen species-generating enzyme Nox4 [NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase-4] and an impaired capacity to induce the Nrf2 (NFE2-related factor 2) antioxidant response. Lung tissues from human subjects with idiopathic pulmonary fibrosis (IPF), a progressive and fatal lung disease, also demonstrated this Nox4-Nrf2 imbalance. Nox4 mediated senescence and apoptosis resistance in IPF fibroblasts. Genetic and pharmacological targeting of Nox4 in aged mice with established fibrosis attenuated the senescent, antiapoptotic myofibroblast phenotype and led to a reversal of persistent fibrosis. These studies suggest that loss of cellular redox homeostasis promotes profibrotic myofibroblast phenotypes that result in persistent fibrosis associated with aging. Our studies suggest that restoration of Nox4-Nrf2 redox balance in myofibroblasts may be a therapeutic strategy in age-associated fibrotic disorders, potentially able to resolve persistent fibrosis or even reverse its progression.
Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Louise
L
Hecker
Naomi J
NJ
Logsdon
Deepali
D
Kurundkar
Ashish
A
Kurundkar
Karen
K
Bernard
Thomas
T
Hock
Eric
E
Meldrum
Yan Y
YY
Sanders
Victor J
VJ
Thannickal
D000375:Aging / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000378:metabolism* / Q000473:pathology*; D055370:Lung Injury / Q000378:metabolism / Q000473:pathology; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D058990:Molecular Targeted Therapy; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010641:Phenotype
D000975:Antioxidants; D051267:NF-E2-Related Factor 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; C422943:Nox4 protein, mouse