Di-san junyi daxue xuebao (Apr 2021)
Effect and mechanism of vanin-1 knockout in promoting recovery of kidney function after renal ischemia reperfusion injury in mice
Abstract
Objective To explore the expression level of vascular noninflammatory molecule-1 (Vanin-1) in renal tissue after renal ischemia-reperfusion (I/R) injury and its relationship with the recovery of renal function. Methods Eight-week-old male BALB/c wild-type and Vanin-1 knockout mice were subjected in this study. They were randomly divided into sham operation group, I/R group, knockout group, knockout+ I/R group, with 6 mice in each group. In the I/R model groups, the bilateral renal pedicles were separated and clamped for 35 min, and then the clamp was released to restore blood flow. For the sham operation and knockout groups, only the renal pedicles were exposed without clipping. Serum, urine, and kidney tissue specimens were collected at 0, 3, and 14 d after surgery to determine blood creatinine and urea nitrogen levels and urine TGF-β level. PAS staining was used to determine the severity of renal tissue damage, and immunohistochemical assay was employed to test the expression of Vanin-1 in renal tissue. After renal tubular epithelial cells were isolated from the kidneys of the wild-type and Vanin-1 knockout mice, the cells were primarily cultured and then passed down to the second generation. Then the cells were divided into control group, injury group, knockout group, and knockout+injury group. The cell injury was inflicted with culture condition of hypoxia (1%O2, 94%N2, 5%CO2) for 48 h followed by reoxygenation (5%CO2, 95% air) for 24 h to simulate in vitro I/R injury model. The expression of Vanin-1 and supernatant content of TGF-β were measured. Results In 3 d after I/R injury, serum creatinine and urea nitrogen levels were significantly higher (P < 0.05), and PAS staining indicated obvious renal tissue damage in the I/R and knockout+I/R groups when compared the sham operation group. But there were no significant differences in the levels and the tissue damages between the I/R and knockout+I/R groups. However, on the 14th day after I/R injury, the 2 groups got the serum creatinine and urea nitrogen levels and renal tissue damage significantly recovered than the conditions on the 3rd day, but the knockout+I/R group recovered significantly faster and obtained milder renal damage (P < 0.05), lower urine TGF-β level and higher Vanin-1 level when compared with the I/R group. In the in vitro study, the mimic I/R injury resulted in obviously increased Vanin-1 level (P < 0.01), and increased TGF-β content in the supernatant (P < 0.05) in the renal tubular epithelial cells when compared in the cells of the knockout+I/R group. Conclusion Vanin-1 promotes the secretion of TGF-β in renal tubular epithelial cells after I/R injury, delays the recovery of renal function, and promotes the progression of acute kidney injury (AKI) to chronic kidney disease (CKD).
Keywords
