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Kidney Int. 2019 Mar;95(3):526-539. doi: 10.1016/j.kint.2018.10.017. Epub 2019 Jan 17.

Myofibroblasts acquire retinoic acid-producing ability during fibroblast-to-myofibroblast transition following kidney injury.

Author information

1
Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
2
Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan; TMK Project, Kyoto University Graduate School of Medicine, Kyoto, Japan.
3
Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan; Nephrology Research Laboratories, Nephrology R&D Unit, R&D Division, Kyowa Hakko Kirin.
4
TMK Project, Kyoto University Graduate School of Medicine, Kyoto, Japan; Research Unit/Nephrological & Endocrinological Science, Sohyaku, Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, Saitama, Japan.
5
Center for Renal Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio.
6
Graduate School of Biological Sciences, Institute for Research Initiatives, Nara Institute of Science and Technology, Nara, Japan.
7
Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan. Electronic address: motoy@kuhp.kyoto-u.ac.jp.

Abstract

Tubular injury and interstitial fibrosis are the hallmarks of chronic kidney disease. While recent studies have verified that proximal tubular injury triggers interstitial fibrosis, the impact of fibrosis on tubular injury and regeneration remains poorly understood. We generated a novel mouse model expressing diphtheria toxin receptor on renal fibroblasts to allow for the selective disruption of renal fibroblast function. Administration of diphtheria toxin induced upregulation of the tubular injury marker Ngal and caused tubular proliferation in healthy kidneys, whereas administration of diphtheria toxin attenuated tubular regeneration in fibrotic kidneys. Microarray analysis revealed down-regulation of the retinol biosynthesis pathway in diphtheria toxin-treated kidneys. Healthy proximal tubules expressed retinaldehyde dehydrogenase 2 (RALDH2), a rate-limiting enzyme in retinoic acid biosynthesis. After injury, proximal tubules lost RALDH2 expression, whereas renal fibroblasts acquired strong expression of RALDH2 during the transition to myofibroblasts in several models of kidney injury. The retinoic acid receptor (RAR) RARγ was expressed in proximal tubules both with and without injury, and αB-crystallin, the product of an RAR target gene, was strongly expressed in proximal tubules after injury. Furthermore, BMS493, an inverse agonist of RARs, significantly attenuated tubular proliferation in vitro. In human biopsy tissue from patients with IgA nephropathy, detection of RALDH2 in the interstitium correlated with older age and lower kidney function. These results suggest a role of retinoic acid signaling and cross-talk between fibroblasts and tubular epithelial cells during tubular injury and regeneration, and may suggest a beneficial effect of fibrosis in the early response to injury.

KEYWORDS:

chronic kidney disease; fibroblast; fibrosis; proximal tubule

PMID:
30661714
DOI:
10.1016/j.kint.2018.10.017

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