Targeted delivery of cytokine therapy to rheumatoid tissue by a synovial targeting peptide
- Sarah E Wythe1,
- Danielle DiCara1,
- Taher E I Taher1,
- Ciara M Finucane2,
- Rita Jones1,
- Michele Bombardieri1,
- Y K Stella Man3,
- Ahuva Nissim3,
- Stephen J Mather2,
- Yuti Chernajovsky3,
- Costantino Pitzalis1
- 1Centre for Experimental Medicine and Rheumatology, John Vane Science Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, London, UK
- 2Centre for Molecular Oncology and Imaging, John Vane Science Centre, Institute of Cancer, Barts and the London School of Medicine and Dentistry, London, UK
- 3Bone and Joint Research Unit, John Vane Science Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, London, UK
- Correspondence to Professor Costantino Pitzalis, Centre for Experimental Medicine and Rheumatology, John Vane Science Centre, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, 2nd Floor John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK;
- Received 2 February 2012
- Accepted 3 July 2012
- Published Online First 27 July 2012
Objectives The synovial endothelium targeting peptide (SyETP) CKSTHDRLC has been identified previously and was shown to preferentially localise to synovial xenografts in the human/severe combined immunodeficient (SCID) mouse chimera model of rheumatoid arthritis (RA). The objective of the current work was to generate SyETP-anti-inflammatory-cytokine fusion proteins that would deliver bioactive cytokines specifically to human synovial tissue.
Methods Fusion proteins consisting of human interleukin (IL)-4 linked via a matrix metalloproteinase (MMP)-cleavable sequence to multiple copies of either SyETP or scrambled control peptide were expressed in insect cells, purified by Ni-chelate chromatography and bioactivity tested in vitro. The ability of SyETP to retain bioactive cytokine in synovial but not control skin xenografts in SCID mice was determined by in vivo imaging using nano-single-photon emission computed tomography-computed tomography (nano-SPECT-CT) and measuring signal transducer and activator of transcription 6 (STAT6) phosphorylation in synovial grafts following intravenous administration of the fusion protein.
Results In vitro assays confirmed that IL-4 and the MMP-cleavable sequence were functional. IL-4-SyETP augmented production of IL-1 receptor antagonist (IL-1ra) by fibroblast-like synoviocytes (FLS) stimulated with IL-1β in a dose-dependent manner. In vivo imaging showed that IL-4-SyETP was retained in synovial but not in skin tissue grafts and the period of retention was significantly enhanced through increasing the number of SyETP copies from one to three. Finally, retention correlated with increased bioactivity of the cytokine as quantified by STAT6 phosphorylation in synovial grafts.
Conclusions The present work demonstrates that SyETP specifically delivers fused IL-4 to human rheumatoid synovium transplanted into SCID mice, thus providing a proof of concept for peptide-targeted tissue-specific immunotherapy in RA. This technology is potentially applicable to other biological treatments providing enhanced potency to inflammatory sites and reducing systemic toxicity.
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