Genetic deletion of DUSP3 phosphatase attenuates kidney damage and inflammation following ischemia/reperfusion in mouse

Background. Renal ischemia-reperfusion (I/R) injury represents an unavoidable event in kidney transplantation. Dual Specificity Phosphatase 3 (DUSP3, also called Vaccinia-H1 Related (VHR)) is highly expressed in endothelial cells, as well as in platelets, monocytes and macrophages. Since DUSP3 is a positive regulator of the innate immune response, its inactivation/deletion may attenuate kidney inflammation and damage caused by I/R.

Methods. Ten-weeks-old C57BL/6 wild-type (WT, n=10) versus systemic knock-out (KO, n=10) mice underwent unilateral left renal ischemia for 30 minutes. Right nephrectomy was simultaneously performed. The left kidney was excised and blood sample was collected from inferior vena cava at 48h post reperfusion. Renal function was assessed upon Blood Urea Nitrogen (BUN) levels. Expressions of inflammatory and immune markers were comparatively quantified at both mRNA (real-time qPCR) and protein (immune-blotting and –staining) levels in ischemic vs. non-ischemic kidneys in DUSP3 WT vs. KO mice.

Results. BUN reached 259±51 vs 78±11mg/dL in WT and KO, respectively (p<0.01). DUSP3 KO ischemic kidneys showed a reduced number of PCNA- (3-fold, p<0.001), CD11b- (3.5-fold, p<0.001) and F4-80-positive cells (1.7-fold, p<0.001) in comparison to WT. The expression levels of CD11b (2.2-fold, p<0.01), HSP70 (2.7-fold, p<0.01) and PCNA (10-fold, p<0.001) were significantly decreased in DUSP3 KO compared to WT ischemic kidneys. By contrast, a 1.5-fold increase of anti-inflammatory M2 CD206-positive macrophages was observed in DUSP3 KO ischemic kidneys. At transcriptional levels, DUSP3 WT vs. KO ischemic kidneys (normalized to WT sham-operated right kidneys) showed an upregulation of 6.5-fold (p<0.05) vs. 10.5-fold (p<0.01) of M2-type macrophage (Arginase), 4.6-fold (p<0.001) vs. 2.2-fold (p<0.05) of CD11b, 4.5-fold (p<0.001) vs. 0.7-fold (p>0.05) of TNF and 111-fold (p<0.001) vs. 4.5-fold (p>0.05) of KIM-1, respectively.

Conclusions. Genetic deletion of DUSP3 attenuates renal I/R-associated damage and inflammation.