Ablation of Gadd45β ameliorates the inflammation and renal fibrosis caused by unilateral ureteral obstruction.

The growth arrest and DNA damage-inducible beta (Gadd45 beta) protein have been associated with various cellular functions, but its role in progressive renal disease is currently unknown. Here, we examined the effect of Gadd45 beta deletion on cell proliferation and apoptosis, inflammation, and renal fibrosis in an early chronic kidney disease (CKD) mouse model following unilateral ureteral obstruction (UUO). Wild-type (WT) and Gadd45 beta-knockout (KO) mice underwent either a sham operation or UUO and the kidneys were sampled eight days later. A histological assay revealed that ablation of Gadd45 beta ameliorated UUO-induced renal injury. Cell proliferation was higher in Gadd45 beta KO mouse kidneys, but apoptosis was similar in both genotypes after UUO. Expression of pro-inflammatory cytokines after UUO was down-regulated in the kidneys from Gadd45 beta KO mice, whereas UUO-mediated immune cell infiltration remained unchanged. The expression of pro-inflammatory cytokines in response to LPS stimulation decreased in bone marrow-derived macrophages from Gadd45 beta KO mice compared with that in WT mice. Importantly, UUO-induced renal fibrosis was ameliorated in Gadd45 beta KO mice unlike in WT mice. Gadd45 beta was involved in TGF-beta signalling pathway regulation in kidney fibroblasts. Our findings demonstrate that Gadd45 beta plays a crucial role in renal injury and may be a therapeutic target for the treatment of CKD.