title: Knockdown of intraislet IKKβ by spherical nucleic acid conjugates prevents cytokine-induced injury and enhances graft survival.
abstract: BACKGROUND
  The efficiency of islet graft survival after intraportal implantation is compromised by host innate immune responses and the production of proinflammatory cytokines that cause acute cellular injury. This reaction activates intraislet nuclear factor-κB (NF-κB), causing production of gene products that have detrimental effects on β-cell survival and function. We hypothesized that small interfering RNA targeting of IKKβ, a crucial kinase in the NF-κB activation pathway, in islets before transplantation would ameliorate the detrimental effects of cytokines and improve islet survival after transplantation.
  
  
  METHODS
  To test this hypothesis, we prepared small interfering RNA-based spherical nucleic acid nanoparticle conjugates targeting IKKβ IKKβ SNA-NCs). We treated isolated islets with IKKβ SNA-NCs and assessed the functional consequences of IKKβ knockdown in vitro and after intraportal transplantation in mice.
  
  
  RESULTS
  Treatment of freshly isolated mouse islets with IKKβ SNA-NCs reduced constitutive IKKβ expression and protected against proinflammatory cytokine-induced NF-κB activation, resulting in improved cell viability and decreased expression of gene products associated with β-cell dysfunction. Intraportal transplantation of a marginal mass (50 islets) of syngeneic islets treated with nanoparticle conjugates targeting IKKβ resulted in reversion to normoglycemia in 50% of streptozotocin-induced diabetic recipients (n=12) compared with 0% of controls (n=12). Histologic analyses showed reduced CD11b(+) cellular infiltration and decreased islet apoptosis.
  
  
  CONCLUSIONS
  These results are consistent with the hypothesis that inhibition of intraislet NF-κB activation ameliorates the detrimental effects of host cytokines and demonstrates that preconditioning freshly isolated islets in culture with IKKβ SNA-NCs may be a promising therapy to enhance islet graft function and survival after transplantation.
authors.affiliation: 1 Department of Urology, Northwestern University, Chicago, IL. 2 Institute for BioNanotechnology in Medicine, Northwestern University, Chicago, IL. 3 Comprehensive Transplant Center, Northwestern University, Chicago, IL. 4 Department of Surgery, Northwestern University, Chicago, IL. 5 Columbia Center for Translational Immunology, Columbia University, New York, NY. 6 International Institute for Nanotechnology, Northwestern University, Evanston, IL. 7 Department of Chemistry, Northwestern University, Evanston, IL. 8 Division of Transplantation, Department of Surgery, University of Wisconsin, Madison, WI. 9 Address correspondence to: Dixon B. Kaufman, M.D., Ph.D., Division of Transplantation, Department of Surgery, University of Wisconsin, H5/701 Clinical Sciences Center, 600 Highland Avenue, Madison, WI 53792-7375.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Rink
authors.forename: Kaylin M
authors.initials: KM
authors.lastname: McMahon
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Chen
authors.forename: Chad A
authors.initials: CA
authors.lastname: Mirkin
authors.forename: C Shad
authors.initials: CS
authors.lastname: Thaxton
authors.forename: Dixon B
authors.initials: DB
authors.lastname: Kaufman
mesh_terms: D000818:Animals; D017209:Apoptosis; D016207:Cytokines / Q000633:toxicity; D003921:Diabetes Mellitus, Experimental / Q000601:surgery*; D005786:Gene Expression Regulation; D006084:Graft Rejection / Q000201:enzymology / Q000235:genetics* / Q000517:prevention & control; D006085:Graft Survival / Q000235:genetics*; D051550:I-kappa B Kinase / Q000096:biosynthesis / Q000235:genetics*; D016381:Islets of Langerhans Transplantation; D051379:Mice; D018345:Mice, Knockout; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics*
chemical_list: D016207:Cytokines; D012313:RNA; D051550:I-kappa B Kinase