IFN-γ Enhances the Therapeutic Effect of Mscs on Experimental Renal Fibrosis

Background:Mesenchymal stem cells (MSCs) administered for therapeutic purposes can be activated by interferon-γ (IFN-γ) secreted from natural killer cells in injured tissues and exert anti-inflammatory effects. These processes may require a substantial period of time, leading to a delayed onset of MSCs therapeutic effects. Here, we investigatedwhetherpretreatment with IFN-γ potentiates the anti-fibrotic and anti-inflammatory activities of MSCs in an injured kidney. Methods:MSCs with or without IFN-γ treatment were injected into rats after ischemia-reperfusion injury (IRI) or unilateral ureter obstruction (UUO) to evaluate the therapeutic effect of IFN-γ-treated MSCs. In addition, we used conditioned medium obtained from IFN-γ-treated MSCs to investigate fibrotic change in cultured cells induced by transforming growth factor-β1 and phenotypic change of macrophages using THP-1 monocytes.Results:Administration of MSCs treated with IFN-γ strongly ameliorated renal fibrosis and inflammation in rat IRI and UUO models compared with that of untreated MSCs. In vitro experiments demonstrated that IFN-γ treatment enhanced the anti-fibrotic effects of MSCs by inhibiting the transforming growth factor-β1/Smad signaling pathway. Most notably, secretion of prostaglandin E2 from MSCs was significantly increased by treatment with IFN-γ. Increased prostaglandin E2 induced polarization of immunosuppressive CD163-positive macrophages. In addition, knockdown of prostaglandin E synthase weakened the anti-fibrotic effects of MSCs treated with IFN-γ in IRI rats, suggesting the involvement of prostaglandin E2 in the beneficial effects of IFN-γ.Conclusions:Administration of MSCs treated with IFN-γ may represent a promising therapy to prevent the progression of renal fibrosis.