The swan-neck lesion: proximal tubular adaptation to oxidative stress in nephropathic cystinosis.

TitleThe swan-neck lesion: proximal tubular adaptation to oxidative stress in nephropathic cystinosis.
Publication TypeJournal Article
Year of Publication2015
AuthorsGalarreta, CI, Forbes, MS, Thornhill, BA, Antignac, C, Gubler, M-C, Nevo, N, Murphy, MP, Chevalier, RL
JournalAm J Physiol Renal Physiol
Volume308
Issue10
PaginationF1155-66
Date Published2015 May 15
ISSN1522-1466
KeywordsAdaptation, Physiological, Amino Acid Transport Systems, Neutral, Animals, Antioxidants, Apoptosis, Cystinosis, Disease Models, Animal, Female, Hepatitis A Virus Cellular Receptor 1, Kidney Tubules, Proximal, Male, Membrane Proteins, Mice, Mice, Inbred C57BL, Mice, Knockout, Mitochondria, Mutation, Organophosphorus Compounds, Oxidative Stress, Superoxides, Ubiquinone
Abstract

Cystinosis is an inherited disorder resulting from a mutation in the CTNS gene, causing progressive proximal tubular cell flattening, the so-called swan-neck lesion (SNL), and eventual renal failure. To determine the role of oxidative stress in cystinosis, histologic sections of kidneys from C57BL/6 Ctns(-/-) and wild-type mice were examined by immunohistochemistry and morphometry from 1 wk to 20 mo of age. Additional mice were treated from 1 to 6 mo with vehicle or mitoquinone (MitoQ), an antioxidant targeted to mitochondria. The leading edge of the SNL lost mitochondria and superoxide production, and became surrounded by a thickened tubular basement membrane. Progression of the SNL as determined by staining with lectin from Lotus tetragonolobus accelerated after 3 mo, but was delayed by treatment with MitoQ (38 ± 4% vs. 28 ± 1%, P < 0.01). Through 9 mo, glomeruli had retained renin staining and intact macula densa, whereas SNL expressed transgelin, an actin-binding protein, but neither kidney injury molecule-1 (KIM-1) nor cell death was observed. After 9 mo, clusters of proximal tubules exhibited localized oxidative stress (4-hydroxynonenal binding), expressed KIM-1, and underwent apoptosis, leading to the formation of atubular glomeruli and accumulation of interstitial collagen. We conclude that nephron integrity is initially maintained in the Ctns(-/-) mouse by adaptive flattening of cells of the SNL through loss of mitochondria, upregulation of transgelin, and thickened basement membrane. This adaptation ultimately fails in adulthood, with proximal tubular disruption, formation of atubular glomeruli, and renal failure. Antioxidant treatment targeted to mitochondria delays initiation of the SNL, and may provide therapeutic benefit in children with cystinosis.

DOI10.1152/ajprenal.00591.2014
Alternate JournalAm. J. Physiol. Renal Physiol.
Citation Key10.1152/ajprenal.00591.2014
PubMed ID25694483
Grant ListMC_U105663142 / / Medical Research Council / United Kingdom