Novel engineered targeted interferon-gamma blocks hepatic fibrogenesis in mice

Abstract

Liver fibrogenesis is a process tightly controlled by endogenous anti-and pro-fibrogenic factors. Interferon gamma (IFNc) is a potent antifibrogenic cytokine in vitro and might therefore represent a powerful therapeutic entity. However, its poor pharmacokinetics and adverse effects, due to the presence of IFNc receptors on nearly all cells, prevented its clinical application so far. We hypothesized that delivery of IFNc specifically to the disease-inducing cells and concurrently avoiding its binding to nontarget cells might increase therapeutic efficacy and avoid side effects. We conjugated IFNc to a cyclic peptide recognizing the plateletderived growth factor beta receptor (PDGFbR) which is strongly up-regulated on activated hepatic stellate cells (HSC), the key effector cells responsible for hepatic fibrogenesis. The IFNc conjugates were analyzed in vitro for PDGFbR-specific binding and biological effects and in vivo in acute (early) and chronic (progressive and established) carbon-tetrachlorideinduced liver fibrosis in mice. The targeted-IFNc construct showed PDGFbR-specific binding to fibroblasts and HSC and inhibited their activation in vitro. In vivo, the targeted-IFNc construct attenuated local HSC activation in an acute liver injury model. In the established liver fibrosis model, it not only strongly inhibited fibrogenesis but also induced fibrolysis. In contrast, nontargeted IFNc was ineffective in both models. Moreover, in contrast to unmodified IFNc, our engineered targeted-IFNc did not induce IFNc-related side effects such as systemic inflammation, hyperthermia, elevated plasma triglyceride levels, and neurotropic effects. Conclusion: This study presents a novel HSC-targeted engineered-IFNc, which in contrast to systemic IFNc, blocked liver fibrogenesis and is devoid of side effects, by specifically acting on the key pathogenic cells within the liver. (HEPATOLOGY 2011;54:586-596)

Selective delivery of IFN‐γ to renal interstitial myofibroblasts: a novel strategy for the treatment of renal fibrosis

“…Therefore, systemic delivery of IFN-g results in immune cell and endothelial cell activation, flu-like symptoms, neurotropic effects, hyperlipidemia, elevated TNF-a and IL-6, CNS inflammation, and elevated triglycerides. Conspicuously, these side effects were almost completely absent following PEG-PPB-IFN-g administration (30), as also evidenced in this study by reduced brain MHC class II expression.…”

“…This region is able to modulate IFN-g-responsive genes through activation of the JAK/STAT (Janus kinase/ signal transducers and activators of transcription signaling pathway) pathway (65,66). We indeed previously showed activation of STAT1 by PEG-PPB-IFN-g (30). We therefore propose that PEG-PPB-IFN-g is taken up via PDGFRb, and the internalized construct next releases IFN-g or its metabolite intracellularly, which binds to IFN-g receptor 1 (IFN-gR1).…”

“…We previously reported reduced side effects of PPB-PEG-IFN-g treatment when compared with free IFN-g (30). To follow up on this, we here determined MHC II mRNA expression in brain tissue (as readout for systemic adverse effects) from UUO mice (d 7).…”

“…Mesenchymal-derived cells including fibroblasts and pericytes constitutively express platelet-derived growth factor receptor b (PDGFRb) at a low level at physiologic conditions, whereas tissue injury is accompanied by increased expression of this receptor (24)(25)(26)(27)(28). An attractive approach for myofibroblast-specific delivery of IFN-g could therefore be based on the recognition of PDGFRb, which can be achieved by the use of a PDGFRb-recognizing cyclic peptide (PPB) (29)(30)(31). This carrier increases the half-life of drugs and also imparts receptor specificity by binding specifically to PDGFRb and, therefore, can be used for drug targeting to activated fibroblasts.…”

Selective Targeting of Interferon γ to Stromal Fibroblasts and Pericytes as a Novel Therapeutic Approach to Inhibit Angiogenesis and Tumor Growth

“…21,22) for specific targeting to PDGFbR-expressing tumor stromal cells. Furthermore, we have shown that pPB-mediated targeting of IFNg to hepatic stellate cells, expressing high levels of PDGFbR during liver fibrosis, completely abolished advanced liver cirrhosis in mice (23). In this study, we delivered IFNg to stromal fibroblasts and pericytes using pPB-HSA carrier to impair angiogenesis thereby inhibiting the tumor growth, whereas avoiding IFNgmediated off-target effects.…”