Abstract: Objective To investigate the role of SPP1 gene in acute kidney injury induced by renal ischemia-reperfusion injury (IRI). Methods Twelve Sprague-Dawley rats were randomly divided into sham group and IRI group (n=6) and subjected to sham operation and renal ischemia for 30 min induced by penal pedicle clamping using non-traumatic microvascular clamps, respectively. Serum creatinine and blood urea nitrogen levels were detected, and PAS staining was used for pathological examination of the kidneys in the two groups. The renal expressions of SPP1, α-SMA and caspase-3 were detected using immunohistochemistry and immunofluorescent staining. In cultured renal tubular epithelial cells (HK-2 cells), Western blotting was performed to detect the changes in expressions of SPP1, caspase-3, and Kim-1 proteins following hypoxia-reoxygenation (H/R) and transfection with si-NC or si-SPP1; flow cytometry was employed to analyze apoptosis of the treated cells. Results Renal IRI caused significant elevations of serum creatinine and blood urea nitrogen levels (P<0.05) and induced severe shedding and necrosis of the renal tubular epithelial cells in the rats, resulting also in significantly up-regulated renal expressions of SPP1, α-SMA and caspase-3 (P<0.05). In HK-2 cells, H/R significantly increased the protein expression levels of SPP1, caspase-3, and Kim-1 (P<0.05), and compared si-NC transfection, transfection with SPP1 obviously reduced caspase-3 and Kim-1 expressions and lowered apoptosis rate of the cells with H/R exposure (P<0.05). Conclusion SPP1 is up-regulated in the kidneys of rats with renal IRI, and down-regulation of SPP1 expression can inhibit H/R-induced apoptosis of renal tubular epithelial cells.

Key words: ischemia-reperfusion injury; SPP1; HK-2 cells; hypoxia-reoxygenation; apoptosis