Generation of an efficiently secreted, cell penetrating NF-κB inhibitor.

Gene therapy is a powerful approach to treat disease locally. However, if the therapeutic target is intracellular, the therapeutic will be effective only in the cells where the therapeutic gene is delivered. We have engineered a fusion protein containing an intracellular inhibitor of the transcription factor NF-κB pathway that can be effectively secreted from producing cells. This fusion protein is cleaved extracellularly by metalloproteinases allowing release of a protein transduction domain (PTD) linked to the NF-κB inhibitor for translocation into neighboring cells. We show that engineered molecules can be efficiently secreted (>80%); are cleaved with matrix metalloprotease-1; inhibit NF-κB driven transcription in a biological assay with a human reporter cell line; and display significant inhibition in mouse paw inflammation models when delivered by lentivirus or secreting cells. No inhibition of NF-κB transcription or therapeutic effect was seen using molecules devoid of the PTD and NF-κB inhibitory domains. By creating a fusion protein with an endogenous secretion partner, we demonstrate a novel approach to efficiently secrete PTD-containing protein domains, overcoming previous limitations, and allowing for potent paracrine effects.

Latency can be conferred to a variety of cytokines by fusion with latency-associated peptide from TGF-ß.

OBJECTIVES: Targeting cytokines to sites of disease has clear advantages because it increases their therapeutic index. We designed fusion proteins of the latent-associated peptide (LAP) derived from TGF-ß with various cytokines via a matrix metalloproteinase (MMP) cleavage site. This design confers latency, increased half-life and targeting to sites of inflammation. The aim of this study is to determine whether this approach can be applied to cytokines of different molecular structures and sizes. METHODS: Mature cytokines cloned downstream of LAP and a MMP cleavage site were expressed in 293T cells and assessed for latency and biological activity by Western blotting and bioassay. RESULTS: We demonstrate here that fusion proteins of TGF-ß, erythropoietin, IL-1ra, IL-10, IL-4, BMP-7, IGF1 and IL-17 were rendered latent by fusion to LAP, requiring cleavage to become active in respective bioassays. As further proof of principle, we also show that delivery of engineered TGF-ß can inhibit experimental autoimmune encephalomyelitis and that this approach can be used to efficiently deliver cytokines to the brain and spinal cord in mice with this disease. CONCLUSIONS: The latent cytokine approach can be successfully applied to a range of molecules, including cytokines of different molecular structure and mass, growth factors and a cytokine antagonist.

Latent cytokines for targeted therapy of inflammatory disorders.

INTRODUCTION: The use of cytokines as therapeutic agents is important, given their potent biological effects. However, this very potency, coupled with the pleiotropic nature and short half-life of these molecules, has limited their therapeutic use. Strategies to increase the half-life and to decrease toxicity are necessary to allow effective treatment with these molecules. AREAS COVERED: A number of strategies are used to overcome the natural limitations of cytokines, including PEGylation, encapsulation in liposomes, fusion to targeting peptides or antibodies and latent cytokines. Latent cytokines are engineered using the latency-associated peptide of transforming growth factor-ß to produce therapeutic cytokines/peptides that are released only at the site of disease by cleavage with disease-induced matrix metalloproteinases. The principles underlying the latent cytokine technology are described and are compared to other methods of cytokine delivery. The potential of this technology for developing novel therapeutic strategies for the treatment of diseases with an inflammatory-mediated component is discussed. EXPERT OPINION: Methods of therapeutic cytokine delivery are addressed. The latent cytokine technology holds significant advantages over other methods of drug delivery by providing simultaneously increased half-life and localised drug delivery without systemic effects. Cytokines that failed clinical trials should be reassessed using this delivery system.