Renal tubular epithelial cell injury and oxidative stress induce calcium oxalate crystal formation in mouse kidney.
OBJECTIVE
To clarify the role of renal tubular cell (RTC) injury and oxidative stress in the early stage of renal calcium oxalate crystal formation in a mouse model.


METHODS
Daily intra-abdominal injections of glyoxylate (1.35 mmol/kg/day) into 8-week-old mice were carried out over 6 days. Kidneys were extracted before and at 6, 12 and 24 h and 3 and 6 days after glyoxylate injection. Crystal formation was detected using Pizzolato staining and polarized light optical microscopy. Immunohistochemical staining and western blotting of superoxide dismutase, and 4-hydroxynonenal and malondialdehyde were carried out in order to observe oxidative stress and lipid peroxidation, respectively. RTC microstructural damage and crystal nuclei formation were observed using transmission electron microscopy. To ameliorate RTC injury, mice were treated with green tea 1 week before and 1 week after glyoxylate administration. The number of crystals and RTC damage were observed and comparisons were made between glyoxylate-treated mice with and without green tea administration.


RESULTS
Oxidative stress and lipid peroxidation were observed after 6 h. Crystal nuclei containing collapsed mitochondria and fallen microvilli appeared in the renal distal tubular lumen after 24 h. Crystals occupying the tubular lumen were detected on day 3. The number of crystals in mice receiving green tea was significantly lower than in those receiving glyoxylate alone.


CONCLUSIONS
RTC injury, especially mitochondrial damage, and oxidative stress induce the early stage of calcium oxalate crystal formation in mice.
Hirose
Masahito
M
Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan.
Yasui
Takahiro
T
Okada
Atsushi
A
Hamamoto
Shuzo
S
Shimizu
Hideo
H
Itoh
Yasunori
Y
Tozawa
Keiichi
K
Kohri
Kenjiro
K
D000818:Animals; D002129:Calcium Oxalate; D003460:Crystallization; D004847:Epithelial Cells / Q000473:pathology*; D007684:Kidney Tubules / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D018384:Oxidative Stress
D002129:Calcium Oxalate