Posterior vitreous detachment induced by nattokinase (subtilisin NAT): a novel enzyme for pharmacologic vitreolysis.
OBJECTIVE
To investigate the effects of intravitreal injection of nattokinase (subtilisin NAT), a serine protease that is produced by Bacillus subtilis (natto), for induction of posterior vitreous detachment (PVD).


METHODS
Different doses of nattokinase (1, 0.1, or 0.01 fibrin-degradation units [FU]) or physiologic saline as a control were injected into the vitreous cavity of rabbit eyes. Scanning electron microscopy was used to observe the retinal surfaces of four rabbit eyes per concentration. Histologic alterations were assessed by light microscopy, using four eyes from each group. Electroretinography (ERG) was performed to observe retinal function, ranging from 1 hour to 1 week after the nattokinase (1 or 0.1 FU) or saline solution administration, using four eyes from each group at each time point. Also, findings in all rabbits were monitored by slit lamp examination and by indirect ophthalmoscopy with a 20-D lens.


RESULTS
Scanning electron microscopy showed smooth retinal surfaces, indicating the occurrence of PVD at 30 minutes after intervention in all the experimental eyes injected with 0.1 or 1.0 FU nattokinase, but none of the control eyes. Light microscopy and ERG analysis showed no critical change even after the use of 0.1 FU nattokinase, an amount sufficient to induce PVD. However, toxicity in the forms of preretinal hemorrhage and ERG changes was noted with the higher dose (1 FU) of nattokinase.


CONCLUSIONS
The results suggested that nattokinase is a useful enzyme for pharmacologic vitreolysis because of its efficacy in inducing PVD.
Takano
Akiomi
A
Department of Ophthalmology and Visual Science, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan.
Hirata
Akira
A
Ogasawara
Kazuya
K
Sagara
Nina
N
Inomata
Yasuya
Y
Kawaji
Takahiro
T
Tanihara
Hidenobu
H
D000818:Animals; D004596:Electroretinography; D007267:Injections; D008855:Microscopy, Electron, Scanning; D011817:Rabbits; D012160:Retina / Q000502:physiology / Q000648:ultrastructure; D013381:Subtilisins / Q000494:pharmacology* / Q000633:toxicity; D014822:Vitreous Body / Q000187:drug effects*; D020255:Vitreous Detachment / Q000139:chemically induced* / Q000473:pathology
D013381:Subtilisins; C053771:nattokinase