Expression of stromal cell-derived factor 1 in the acute ischemia-reperfusion injury and its relationship with macrophages

Objective To observe the expression of stromal cell-derived factor 1 (SDF-1) in the kidney after ischemic reperfusion injury (IRI), and explore its relationship with macrophage during the IRI kidney. Methods A total of 28 healthy C57BL/6 male mice were used to establish renal IRI model by clamping both pedicles for 35 min followed by reperfusion. Kidney tissue samples were collected at indicated time points. Renal histological changes were estimated. The expression of SDF-1 was determined by immunohistochemistry, ELISA and real-time PCR. After the liposomal clodronate was injected intraperitoneally, the location of CD68 was observed by immunofluorescence. Renal histology and protein expression of SDF-1 were also detected. Results Compared with sham-operated group, classical tubular damage was found in IRI group, accompanied by a large number of inflammatory cells. The expression of total renal SDF-1 peaked on day 1 and decreased to control levels in the following days. SDF-1 in healthy kidney was localized at cortex, but spread to the corticomedullary area of the kidney during IRI. Compared with IRI groups, elimination of macrophage by injection of liposomal clodronate alleviated renal IRI and down-regulated the expressions of CD68 while up-regulating SDF-1. Conclusions SDF-1 expression is up-regulated in IRI kidney and is associated with macrophage. SDF-1 may play a role in the early phase of acute kidney injury and it may be a new marker in diagnosis of AKI.