Nitrite-modified extracellular matrix proteins deleteriously affect retinal pigment epithelial cell function and viability: a comparison study with nonenzymatic glycation mechanisms.
OBJECTIVE
Extracellular matrix (ECM) plays an important role in the regulation of cell function. The aging process may involve chemical modifications to ECM proteins, which may contribute to the aging of the Bruch membrane and pathogenesis of age-related macular degeneration (AMD). The purpose of this study is to investigate nitrite modification of basement membrane-like proteins on RPE cell behavior as a model for the aging of the Bruch membrane in age-related eye diseases. As a comparison, retinal pigment epithelium (RPE) cell behavior on glycolaldehyde-modified matrices (GMM) was also studied.


METHODS
Growth factor reduced Matrigel was reacted with nitrite or glycolaldehyde for 1 week or 12 hr, respectively. Calf RPE cells were plated on the modified matrices and examined in several ways. Attachment rates, proliferation rates, apoptosis, and necrosis were determined. Cell morphology and cell susceptibility to A2E-mediated damage was also monitored.


RESULTS
Nitrite-modified matrices (NMMs) inhibited cell attachment by 65% and proliferation by 33.7% compared to 69.6% and 21.7%, respectively, by GMM. Proliferation inhibition was not significant when cells were plated at high density on GMM (3.47%) but significant on NMM (20.9%). NMM induced cell apoptosis and necrosis, but GMM induced cell apoptosis only. Both modifications inhibited RPE differentiation. RPE cells on both matrices were more susceptible to blue light mediated damage by A2E, but damage was greater on NMM.


CONCLUSIONS
NMM has significant damaging effects on RPE cell function and viability that is similar to the damaging effects of GMM. These studies may have relevance to the RPE dysfunction observed during the progression of AMD.
Wang
Zhen
Z
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, USA.
Paik
David C
DC
Del Priore
Lucian V
LV
Burch
Robert L
RL
Gaillard
Elizabeth R
ER
D000818:Animals; D017209:Apoptosis; D001485:Basement Membrane / Q000187:drug effects; D002417:Cattle; D002448:Cell Adhesion; D018929:Cell Culture Techniques; D049109:Cell Proliferation; D002470:Cell Survival; D003094:Collagen; D004338:Drug Combinations; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D006031:Glycosylation; D007797:Laminin; D009336:Necrosis; D015538:Nitrosation; D010857:Pigment Epithelium of Eye / Q000166:cytology* / Q000187:drug effects*; D011509:Proteoglycans; D011726:Pyridinium Compounds / Q000633:toxicity; D012176:Retinoids / Q000633:toxicity; D012977:Sodium Nitrite / Q000633:toxicity*
C112040:A2-E (N-retinylidene-N-retinylethanolamine); D004338:Drug Combinations; D016326:Extracellular Matrix Proteins; D007797:Laminin; D011509:Proteoglycans; D011726:Pyridinium Compounds; D012176:Retinoids; C059485:matrigel; D003094:Collagen; D012977:Sodium Nitrite