PMID- 28426715
OWN - NLM
STAT- MEDLINE
DCOM- 20170907
LR  - 20190208
IS  - 1932-6203 (Electronic)
IS  - 1932-6203 (Linking)
VI  - 12
IP  - 4
DP  - 2017
TI  - Acute hypoxia influences collagen and matrix metalloproteinase expression by 
      human keratoconus cells in vitro.
PG  - e0176017
LID - 10.1371/journal.pone.0176017 [doi]
LID - e0176017
AB  - Keratoconus (KC) is a progressive corneal ectasia linked to thinning of the 
      central cornea. Hard contact lenses, rigid gas permeable lenses, and scleral 
      lenses are the primary treatment modalities for early to mid- stages of KC to 
      correct refractive error and astigmatism that develops as a result of an 
      irregular corneal structure. These treatments are associated with significant 
      drawbacks, including reduced availability of the tear film and oxygen to the 
      corneal epithelium and stroma. However, it remains unknown whether hypoxia 
      affects corneal integrity in the KC pathobiology. A number of studies have 
      associated elevated oxidative stress with KC both in vitro and ex vivo. We 
      hypothesized that KC-derived corneal fibroblasts are more susceptible to 
      hypoxia-induced oxidative stress compared to healthy controls leading to 
      exacerbation of corneal thinning in KC. This study investigated the effects of 
      hypoxia on ECM secretion, assembly, and matrix metalloproteinase (MMP) expression 
      in human corneal fibroblasts from healthy controls (HCFs) and KC patients (HKCs) 
      in vitro. HCFs and HKCs were cultured in 3D constructs for 3 weeks and maintained 
      or transferred to normoxic (21% O2) or hypoxic (2% O2) conditions, respectively, 
      for 1 additional week. At the 4 week time-point, constructs were isolated and 
      probed for Collagen I, III, and V, keratocan and MMP-1, -2, -3, -9, and -13, as 
      well as hypoxia markers, hypoxia inducible factor-1alpha and lactoferrin. Conditioned 
      media was also collected and probed for Collagen I, III, and V by Western blot. 
      Thickness of the ECM assembled by HCFs and HKCs was measured using 
      immunofluorescence microscopy. Results showed that hypoxia significantly reduced 
      Collagen I secretion in HKCs, as well as upregulated the expression of MMP-1 and 
      -2 with no significant effects on MMP-3, -9, or -13. ECM thickness was reduced in 
      both cell types following 1 week in a low oxygen environment. Our study shows 
      that hypoxia influences collagen and MMP expression by HKCs, which may have 
      consequential effects on ECM structure in the context of KC.
FAU - McKay, Tina B
AU  - McKay TB
AD  - Department of Cell Biology, University of Oklahoma Health Sciences Center, 
      Oklahoma City, Oklahoma, United States of America.
FAU - Hjortdal, Jesper
AU  - Hjortdal J
AD  - Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark.
FAU - Priyadarsini, Shrestha
AU  - Priyadarsini S
AD  - Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma 
      Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
FAU - Karamichos, Dimitrios
AU  - Karamichos D
AUID- ORCID: 0000-0002-8761-3824
AD  - Department of Cell Biology, University of Oklahoma Health Sciences Center, 
      Oklahoma City, Oklahoma, United States of America.
AD  - Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma 
      Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
LA  - eng
GR  - P30 EY021725/EY/NEI NIH HHS/United States
GR  - R01 EY023568/EY/NEI NIH HHS/United States
PT  - Journal Article
DEP - 20170420
PL  - United States
TA  - PLoS One
JT  - PloS one
JID - 101285081
RN  - 9007-34-5 (Collagen)
RN  - EC 3.4.24.- (Matrix Metalloproteinases)
SB  - IM
MH  - Case-Control Studies
MH  - *Cell Hypoxia
MH  - Cells, Cultured
MH  - Collagen/*metabolism
MH  - Humans
MH  - In Vitro Techniques
MH  - Keratoconus/enzymology/*metabolism/pathology
MH  - Matrix Metalloproteinases/*metabolism
PMC - PMC5398580
COIS- Competing Interests: The authors have declared that no competing interests exist.
EDAT- 2017/04/21 06:00
MHDA- 2017/09/08 06:00
PMCR- 2017/04/20
CRDT- 2017/04/21 06:00
PHST- 2017/02/10 00:00 [received]
PHST- 2017/04/04 00:00 [accepted]
PHST- 2017/04/21 06:00 [entrez]
PHST- 2017/04/21 06:00 [pubmed]
PHST- 2017/09/08 06:00 [medline]
PHST- 2017/04/20 00:00 [pmc-release]
AID - PONE-D-17-05543 [pii]
AID - 10.1371/journal.pone.0176017 [doi]
PST - epublish
SO  - PLoS One. 2017 Apr 20;12(4):e0176017. doi: 10.1371/journal.pone.0176017. 
      eCollection 2017.