Activated NAD(P)H oxidase from supplemental oxygen induces neovascularization independent of VEGF in retinopathy of prematurity model.
OBJECTIVE
To study NAD(P)H oxidase-dependent outcomes after oxygen stresses that are similar to those experienced by preterm infants today using a rat model of retinopathy of prematurity.


METHODS
Within 4 hours of birth, pups and their mothers were cycled between 50% and 10% oxygen daily for 14 days and were returned to room air (21% O2, 50/10 oxygen-induced retinopathy [OIR]) or supplemental oxygen (28% O2, 50/10 OIR+SO) for 4 days. Pups received intraperitoneal injections of the specific NAD(P)H oxidase inhibitor apocynin (10 mg/kg/d) or of PBS from postnatal day (P)12 to P17, and some received intraperitoneal injections of hypoxyprobe before kill. Intravitreous neovascularization (IVNV), avascular/total retinal areas, vascular endothelial growth factor (VEGF), NAD(P)H oxidase activity, or hypoxic retina (conjugated hypoxyprobe) were determined in neurosensory retinas. Human retinal microvascular endothelial cells (RMVECs) treated with apocynin or control were exposed to 1% or 21% O2 and assayed for phosphorylated (p-)Janus kinase (JNK) and NAD(P)H oxidase activity.


RESULTS
Retinas from 50/10 OIR+SO had increased NAD(P)H oxidase activity and lower VEGF than did retinas from 50/10 OIR. Apocynin treatment reduced the IVNV area and hypoxic retina in 50/10 OIR+SO. RMVECs treated with 1% O2 had increased p-JNK compared with RMVECs exposed to room air.


CONCLUSIONS
Different oxygen stresses activate NAD(P)H oxidase to varying degrees to trigger disparate pathways (angiogenesis or apoptosis). The oxygen stresses and outcomes used in this study are relevant to human ROP and may explain some of the complexity in the pathophysiology of ROP resulting from oxygen exposure.
Saito
Yuta
Y
Department of Ophthalmology, Showa University, Tokyo, Japan.
Uppal
Abhineet
A
Byfield
Grace
G
Budd
Steven
S
Hartnett
M Elizabeth
ME
D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D018496:Hyperoxia / Q000150:complications; D047468:Immunoprecipitation; D007231:Infant, Newborn; D007274:Injections, Intraperitoneal; D053612:Janus Kinases / Q000378:metabolism; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D010100:Oxygen / Q000633:toxicity*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015861:Retinal Neovascularization / Q000201:enzymology* / Q000473:pathology; D012178:Retinopathy of Prematurity / Q000201:enzymology* / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
D004791:Enzyme Inhibitors; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D019255:NADPH Oxidases; D053612:Janus Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D010100:Oxygen