title: Targeted delivery of cytokine therapy to rheumatoid tissue by a synovial targeting peptide.
abstract: OBJECTIVE
  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.
authors: William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, London, UK.
authors: Sarah E
authors: SE
authors: Wythe
authors: Danielle
authors: D
authors: DiCara
authors: Taher E I
authors: TE
authors: Taher
authors: Ciara M
authors: CM
authors: Finucane
authors: Rita
authors: R
authors: Jones
authors: Michele
authors: M
authors: Bombardieri
authors: Y K Stella
authors: YK
authors: Man
authors: Ahuva
authors: A
authors: Nissim
authors: Stephen J
authors: SJ
authors: Mather
authors: Yuti
authors: Y
authors: Chernajovsky
authors: Costantino
authors: C
authors: Pitzalis
mesh_terms: D000818:Animals; D001172:Arthritis, Rheumatoid / Q000188:drug therapy; D016207:Cytokines / Q000008:administration & dosage*; D004195:Disease Models, Animal; D016503:Drug Delivery Systems / Q000379:methods*; D006801:Humans; D007167:Immunotherapy / Q000379:methods*; D015847:Interleukin-4 / Q000008:administration & dosage*; D051379:Mice; D016513:Mice, SCID; D064847:Multimodal Imaging; D010455:Peptides / Q000008:administration & dosage; D049268:Positron-Emission Tomography; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage*; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism; D014057:Tomography, X-Ray Computed; D014183:Transplantation, Heterologous
chemical_list: D016207:Cytokines; D010455:Peptides; D011993:Recombinant Fusion Proteins; D015847:Interleukin-4