RETRACTED: Interferon gamma peptidomimetic targeted to interstitial myofibroblasts attenuates renal fibrosis after unilateral ureteral obstruction in mice

Renal fibrosis cannot be adequately treated since anti-fibrotic treatment is lacking. Interferon-γ is a pro-inflammatory cytokine with anti-fibrotic properties. Clinical use of interferon-γ is hampered due to inflammation-mediated systemic side effects. We used an interferon-γ peptidomimetic (mimγ) lacking the extracellular IFNγReceptor recognition domain, and coupled it to the PDGFβR-recognizing peptide BiPPB. Here we tested the efficacy of mimγ-BiPPB (referred to as “Fibroferon”) targeted to PDGFβR-overexpressing interstitial myofibroblasts to attenuate renal fibrosis without inducing inflammation-mediated side effects in the mouse unilateral ureter obstruction model. Unilateral ureter obstruction induced renal fibrosis characterized by significantly increased α-SMA, TGFβ1, fibronectin, and collagens I and III protein and/or mRNA expression. Fibroferon treatment significantly reduced expression of these fibrotic markers. Compared to full-length IFNγ, anti-fibrotic effects of Fibroferon were more pronounced. Unilateral ureter obstruction-induced lymphangiogenesis was significantly reduced by Fibroferon but not full-length IFNγ. In contrast to full-length IFNγ, Fibroferon did not induce IFNγ-related side-effects as evidenced by preserved low-level brain MHC II expression (similar to vehicle), lowered plasma triglyceride levels, and improved weight gain after unilateral ureter obstruction. In conclusion, compared to full-length IFNγ, the IFNγ-peptidomimetic Fibroferon targeted to PDGFβR-overexpressing myofibroblasts attenuates renal fibrosis in the absence of IFNγ-mediated adverse effects.