Mechanism of effect of IL-17C on survival of kidney graft in mice

Objective To investigate the effect and mechanism of interleukin (IL)-17C in mice undergoing kidney transplantation. Methods The life-supporting kidney transplantation mice models were established using Balb/c (H-2Kd) mice as the donors, IL-17C gene knock out (IL-17CKO) mice (knockout group) and C57BL/6J(H-2Kb) mice (wild group) were chosen as the recipients. The postoperative body mass and survival time of mice were statistically compared between two groups. Pathological examination of the kidney graft was performed by using hematoxylin-eosin (HE) staining and periodic acid-Schiff (PAS) staining. The expression levels of granzyme B, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-6 and IL-1β messenger ribonucleic acid (mRNA) in the kidney graft tissue were quantitatively measured by reverse transcription polymerase chain reaction (RT-PCR). The proportion of inflammatory cell infiltration in the kidney graft tissue was detected by flow cytometry. Results In the knockout group, the survival time of mice after kidney transplantation was significantly shorter than that of the wild mice (P=0.031). The body mass was more evidently decreased in the knockout group with no statistical significance from that in the wild group. Pathological examination demonstrated that the kidney graft injury in the knockout group was significantly worse than that in the wild group. The mRNA expression levels of granzyme B, IFN-γ, TNF-α, IL-6 mRNA in the knockout group were significantly up-regulated compared with those in the wild group (all P < 0.01). The mRNA expression level of IL-1β showed a decreasing trend with no statistical significance (P=0.16). Flow cytometry analysis revealed that the infiltration of CD45+CD11b+Ly6G+ neutrophil and CD45+CD11b+Ly6Chi monocyte in the kidney graft of knockout mice was significantly higher compared with that of the wild mice (P < 0.05, P < 0.01), whereas the infiltration of CD45+Ly6ChiF4/80+ macrophage did not significantly differ between two groups (P > 0.05). Conclusions IL-17C participates in the regulation of inflammatory response after kidney transplantation. It can alleviate acute rejection and improve the survival of kidney graft by down-regulating the expression of pro-inflammatory cytokines and infiltration of inflammatory cells.