Increased isolevuglandin-modified proteins in glaucomatous astrocytes.
OBJECTIVE
Lipid oxidation has been proposed to be a factor in the pathophysiology of glaucoma. We investigated whether elevated levels of isolevuglandin (iso[4]LGE(2)) protein adducts are associated with astrocytes derived from the glaucomatous optic nerve head. In addition, we examined whether the iso[4]LGE(2) protein adducts are altered following exposure of astrocytes to elevated pressure.


METHODS
Astrocytes were isolated from rat brain cortex and human optic nerve and were subjected to pressure treatments, western blot analyses, liquid chromatography tandem mass spectrometry, and immunocytochemistry.


RESULTS
Elevated levels of isolevuglandin (iso[4]LGE(2)) protein adducts were associated with astrocytes derived from the glaucomatous (n=10) optic nerve head when compared to those from controls (n=6). Astrocytes subjected to in vitro pressure treatment resulted in increased levels of iso[4]LGE(2) protein adducts. Pressure exposure and the recovery period affect iso[4]LGE(2) protein modification, and pyridoxamine was effective in decreasing the appearance of iso[4]LGE(2) protein adduct immunoreactivity when applied immediately after pressure treatment.


CONCLUSIONS
These results suggest that the elevated iso[4]LGE(2) protein adduct immunoreactivity observed in glaucomatous astrocytes may be due to chronic and/or prolonged exposure to pressure, and pyridoxamine may have prophylactic utility against such oxidative protein modification.
Govindarajan
Bharathi
B
Department of Chemistry, Case Western Reserve University, Cleveland, OH, USA.
Junk
Anna
A
Algeciras
Mabel
M
Salomon
Robert G
RG
Bhattacharya
Sanjoy K
SK
D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002540:Cerebral Cortex / Q000166:cytology; D002648:Child; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005260:Female; D005901:Glaucoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000166:cytology; D018384:Oxidative Stress; D011312:Pressure; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011733:Pyridoxamine / Q000494:pharmacology; D051381:Rats
D005231:Fatty Acids, Unsaturated; C526910:iso(4)levuglandin E2; D011733:Pyridoxamine