Publication: The presence of lysyl oxidase-like enzymes in human control and keratoconic corneas
Authors
Dudakova, Lubica ; Sasaki, Takako ; Liskova, Petra ; Palos, Michalis ; Jirsova, Katerina
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Publisher
Universidad de Murcia. Departamento de Biología Celular e Histología
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DOI
10.14670/HH-11-649
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info:eu-repo/semantics/article
Description
Abstract
Purpose: Lysyl oxidases, a family comprising
lysyl oxidase (LOX) and four LOX-like enzymes
(LOXL1-4), catalyse the cross-linking of elastin and
collagen fibrils. Keratoconus (KC) is characterized by
progressive thinning leading to irregular astigmatism,
resulting in significant visual impairment. Although the
pathogenesis of KC remains unclear, one of the current
hypotheses is based on alterations in the organization
and structure of collagen fibrils. To extend existing
general knowledge about cross-linking enzymes in the
human cornea, in the present study we have focused on
the detection of LOXL enzymes.
Method: The localization and distribution of
LOXL1-4 were assessed in cryosections of 7 control
donors (three males and three females; 25-68 years;
mean age 46±17.6 years) and 8 KC corneas (5 males and
3 females; 25-46 years; mean age 31.3±7.5 years) using
indirect fluorescent immunohistochemistry (IHC). The
specimens were examined using an Olympus BX51
microscope (Olympus Co., Tokyo, Japan) at a
magnification of 200-1000x. Western blot analysis of 4
control and 4 KC corneas was performed for all tested
enzymes.
Results: All four LOX-like enzymes were present in
all layers of control corneas as well as in the limbus and
conjunctiva. Almost no differences between control and
pathological specimens were found for LOXL1. A lower
staining intensity of LOXL2 was found using IHC and
Western blot analysis in KC specimens. Decreases of the
signal and small irregularities in the staining were found
in the epithelium, keratocytes and extracellular matrix,
where a gradual anterior-posterior weakening of the
signal was observed. LOXL3 IHC staining was lower in
the corneal stromal extracellular matrix and keratocytes
of KC samples. No prominent differences were detected
using IHC for LOXL4, but a slight decrease was
observed in KC corneas using Western blot analysis.
Conclusion: We presume that the decrease of
LOXL2 in KC corneas is more likely a consequence of
the associated pathological processes (activation of
stromal cells due to tissue weakening and consequent
structural changes) than a direct cause leading to KC
development. At this time, we are unable to provide a
coherent explanation for the observed decrease of
LOXL3 and LOXL4 in KC corneas.
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Citation
Histology and Histopathology, vol.31, nº 1, (2016)
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