Role of the Dual Specificity Phosphatase 3 (DUSP3) in renal ischemia/reperfusion injury

● Background:
DUSP3 is a positive regulator of the innate immune response in case of sepsis, but its role in the
ischemic damage is unknown. We study (i) whether and where DUSP3 is expressed in the renal
parenchyma, and (ii) whether its genetic deletion in mice (Dusp3-/-) attenuates the ischemic
injury.
● Methods:
Exp1: Ten C57BL/6 male WT and Dusp3-/- mice underwent right nephrectomy and left renal
ischemia(30min)/reperfusion(48h) (I/R). Renal function was assessed upon I/R biomarkers:
serum levels of urea (BUN) and creatinine (SCr). The expression of inflammatory markers was
quantified at both mRNA and protein levels in ischemic vs. non-ischemic kidneys in WT vs
Dusp3-/-.
Exp2: Renal resistivity index (RRI) was measured by Doppler ultrasound (n=10 mice). The
expression of CD31 and VEGF vascular markers was quantified by qPCR and immuno-staining.
● Results:
Exp1: An immuno-reactive signal for DUSP3 was detected in nephrin-positive glomeruli and in
Meca-32-positive endothelial cells in both outer and inner medulla, with no immunoreactivity in
Dusp3-/- kidneys. Following I/R, the mRNA level of DUSP3 was increased 1.8-fold compared to
baseline. Immunoblotting showed a 77-fold increased expression of DUSP3 post I/R. Serum
levels of I/R biomarkers were significantly lower in Dusp3-/- compared to WT mice following renal
I/R (BUN: 78.4±33.7 vs. 258.9±162.9mg/dL; SCr: 0.1±0.07 vs. 0.8±0.9 mg/dL; p<0.01). At mRNA
levels, Dusp3-/- ischemic kidneys showed a significantly decreased expression level of TNF-α,
KIM-1, IL-6, IL-1β and caspase-3 compared to WT. PCNA-, F4-80- and CD11b-positive cells
were significantly reduced in Dusp3-/- vs WT renal parenchyma post I/R.
Exp2: The RRI was lower in Dusp3-/- compared to WT (0.56±0.03 vs. 0.66±0.02; p<0.001). The
Dusp3-/- kidneys were characterized by a 1.8-fold increase of CD31 compared to WT. At mRNA
levels, the Dusp3-/- kidneys showed increased basal levels of CD31 and VEGF compared to WT.
● Conclusions:
The genetic deletion of DUSP3 is associated with (i) increased renal vascular density, (ii)
decreased RRI and (iii) nephroprotection against renal I/R injury.