Objective  To investigate the role and mechanism of growth differentiation factor (GDF) 15 in ischemia-reperfusion injury (IRI) during kidney transplantation.

  Methods  Nine wild type donor mice and 9 wild type recipient mice were selected. The renal graft of 3 recipient mice were harvested at 4, 24 and 72 h after transplantation. GDF family transcriptome analysis was carried out, and the expression of GDF15 in renal tissues of each group were detected. Five wild type donor mice, 5 GDF15 knockout donor mice and 10 wild type recipient mice were selected. According to the experimental scheme, the mice were divided into wild type sham operation group, wild type transplantation group, GDF15 knockout sham operation group and GDF15 knockout transplantation group. Serum and renal tissue samples were extracted 72 h after transplantation. The renal function, renal tubular injury, inflammatory cell infiltration, inflammatory factors, Toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB expression level were compared in each group. Nine wild type donor mice, 9 GDF15 knockout donor mice and 18 wild type recipient mice were selected. According to the experimental scheme, the mice were divided into wild type transplantation group and GDF15 knockout transplantation group, and the survival rate of two group after kidney transplantation was observed.

  Results  Transcriptome sequencing of renal graft tissues indicated that GDF15 was the most up-regulated GDF family gene, which was mainly expressed in renal tubules. Compared with the sham operation group, the renal function of mice was declined in the transplantation group. Compared with the wild type transplantation group, the serum creatinine and blood urea nitrogen levels of mice were significantly up-regulated in the GDF15-knockout transplantation group (both P < 0.05). The 1-week survival rate of mice was 87.6% in the wild type transplantation group and 41.8% in the GDF15 knockout transplantation group. In the GDF15 knockout transplantation group, the expression level of kidney injury molecule (KIM)-1 was up-regulated, and the renal tubule injury score was increased. In the wild type transplantation group, the renal tubules were dissolved or necrotized, and tubular formation was seen in the extramedullary and cortex area, whereas tubular necrosis and tubular formation were more evident in the GDF15 knockout transplantation group. The expression levels of myeloperoxidase (MPO) and F4/80 were up-regulated in the transplantation group, and the inflammatory cell infiltration was aggravated in the GDF15 knockout transplantation group. Compared with the sham operation group, the expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in the transplantation group were up-regulated. Compared with the wild type transplantation group, the expression levels of TNF-α, IL-1β and IL-6 were also up-regulated in the GDF15 knockout transplantation group (all P < 0.05). In the transplantation group, the expression levels of TLR4 and NF-κB in the renal graft tissues were higher than those in the sham operation group. In the GDF15 knockout transplantation group, the expression levels of TLR4 and NF-κB in the renal graft tissues were higher compared with those in the wild type transplantation group.

  Conclusions  GDF15 may alleviate the IRI of renal graft probably via inhibiting the TLR4-NF-κB signaling pathway.