Expression of Gpnmb in the acute ischemia-reperfusion injury and the relationship between Gpnmb and macrophage phenotypes / 中华肾脏病杂志

ABSTRACT

Objective To observe the expression of glycoprotein non-metastatic melanoma protein B (Gpnmb) in the kidney and urine after ischemic-reperfusion injury (IRI),and explore the relationship between Gpnmb and macrophage phenotypes in the IRI kidney.Methods Male C57BL/6J mice were randomly divided into control group (n =4),sham group (n =4) and IRI group (n =12).Both renal pedieles of mice in IRI group were identified and occluded with microvascular clamps for 30 min.Renal pathological injury was observed by PAS staining.The expression of Gpnmb was examined by real-time PCR and immunofluoresence staining.The location of Gpnmb was observed by flow cytometry and double immunofluoresence staining with F4/80.The mRNA expressions of Gpnmb,CD40,CRR7,CD163 and MMR were examined by real-time PCR.The expression of Gpnmb in the urine was examined by Western blotting and ELISA.Results PAS-stained IRI kidney section showed desquamative epithelia,necrosis debris and a large number of inflammatory cell infiltration.Real-time PCR results showed that there was little expression of Gpnmb in the kidney of control group and sham group.However,the Gpnmb mRNA level in IRI kidneys was highly up-regulated at day 1 and day 2 (both P ＜ 0.01) and followed by a decrease that was similar to the control level at day 3.Double immunofluoresence staining of kidney sections from IRI mice revealed that Gpnmb was predominantly detected in F4/80 positive macrophages.The mRNA expression of Gpnmb was not correlated with M1 macrophage phenotypes CD40 and CCR7,but positively correlated with M2 macrophages phenotypes CD163 and MMR.Western blotting and ELISA result showed that there was significant increase of Gpnmb expression in the urine from IRI mice compared to those of the control group and the sham group (P ＜ 0.01).Conclusions Gpnmb expression is up-regulated in IRI kidney and is associated to M2 macrophages.It may play a role in the process of acute kidney injury.Gpnmb expression is also increased in urine after IR injury and it may be a new biomarker to diagnose AKI.