Publication: Upregulation of autophagy and glycolysis markers in keloid hypoxic-zone fibroblasts: Morphological characteristics and implications
Authors
Okuno, Ryoko ; Ito, Yuko ; Eid, Nabil ; Otsuki, Yoshinori ; Kondo, Yoichi ; Ueda, Koichi
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Publisher
Universidad de Murcia. Departamento de Biología Celular e Histología
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DOI
DOI: 10.14670/HH-18-005
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info:eu-repo/semantics/article
Description
Abstract
Keloid is a fibro-proliferative skin disorder
with tumor-like behavior and dependence on anaerobic
glycolysis (the Warburg effect), but its exact
pathogenesis is unknown. Although autophagy is widely
accepted as a lysosomal pathway for cell survival and
cellular homeostasis (specifically upon exposure to
stressors such as hypoxia), very few studies have
investigated the involvement of autophagy and related
glycolytic effectors in keloidogenesis. Here the authors
examined the expression and cellular localization of
autophagy proteins (LC3, pan-cathepsin), glycolytic
markers (LDH, MCT1, MCT4) and the transcription
factor HIF isoforms in human keloid samples using
immunohistochemical analysis and double-labeling
immunofluorescence methods. Based on H&E staining
and expression of CD31, keloids were compartmentalized into hypoxic central and normoxic marginal
zones. Vimentin-expressing fibroblasts in the central
zone exhibited greater autophagy than their marginalzone counterparts, as evidenced by increased LC3
puncta formation and co-localization with lysosomal
pan-cathepsin. LDH (a lactate stimulator), MCT4 (a
lactate exporter) and HIF-1α expression levels were also
higher in central-zone fibroblasts. Conversely, HIF-2α
expression was upregulated in fibroblasts and
endothelial cells of the peripheral zone, while MCT1
was expressed in both zones. Taken together, these
observations suggest that upregulation of autophagy and
glycolysis markers in keloid hypoxic-zone fibroblasts
may indicate a prosurvival mechanism allowing the
extrusion of lactate to marginal-zone fibroblasts via
metabolic coupling. The authors believe this is the first
report on differential expression of autophagic and
glycolytic markers in keloid-zone fibroblasts. The study
results indicate that autophagy inhibitors and MCT4
blockers may have therapeutic implications in keloid
treatment
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Citation
Histology and Histopathology, Vol.33, nº10, (2018)
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