Intravenous Delivery of HIV-Based Lentiviral Vectors Preferentially Transduces F4/80+ and Ly-6C+ Cells in Spleen, Important Target Cells in Autoimmune Arthritis Ben T. van den Brand 1 , Eline A. Vermeij 1 , Claire E. J. Waterborg 1 , Onno J. Arntz 1 , Michael Kracht 2 , Miranda B. Bennink 1 , Wim B. van den Berg 1 , Fons A. J. van de Loo 1 * 1 Rheumatology Research and Advanced Therapeutics, Department of Rheumatology Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands, 2 Rudolf-Buchheim-Institute of Pharmacology, Justus-Liebig-University Giessen, Giessen, Germany Abstract Antigen presenting cells (APCs) play an important role in arthritis and APC specific gene therapeutic targeting will enable intracellular modulation of cell activity. Viral mediated overexpression is a potent approach to achieve adequate transgene expression levels and lentivirus (LV) is useful for sustained expression in target cells. Therefore, we studied the feasibility of lentiviral mediated targeting of APCs in experimental arthritis. Third generation VSV-G pseudotyped self-inactivating (SIN)- LV were injected intravenously and spleen cells were analyzed with flow cytometry for green fluorescent protein (GFP) transgene expression and cell surface markers. Collagen-induced arthritis (CIA) was induced by immunization with bovine collagen type II in complete Freund’s adjuvant. Effect on inflammation was monitored macroscopically and T-cell subsets in spleen were analyzed by flow cytometry. Synovium from arthritic knee joints were analyzed for proinflammatory cytokine expression. Lentiviruses injected via the tail vein preferentially infected the spleen and transduction peaks at day 10. A dose escalating study showed that 8% of all spleen cells were targeted and further analysis showed that predominantly Ly6C+ and F4/80+ cells in spleen were targeted by the LV. To study the feasibility of blocking TAK1-dependent pathways by this approach, a catalytically inactive mutant of TAK1 (TAK1-K63W) was overexpressed during CIA. LV-TAK1-K63W significantly reduced incidence and arthritis severity macroscopically. Further histological analysis showed a significant decrease in bone erosion in LV-TAK1-K63W treated animals. Moreover, systemic Th17 levels were decreased by LV-TAK1-K63W treatment in addition to diminished IL-6 and KC production in inflamed synovium. In conclusion, systemically delivered LV efficiently targets monocytes and macrophages in spleen that are involved in autoimmune arthritis. Moreover, this study confirms efficacy of TAK1 targeting in arthritis. This approach may provide a valuable tool in targeting splenic APCs, to unravel their role in autoimmune arthritis and to identify and validate APC specific therapeutic targets. Citation: van den Brand BT, Vermeij EA, Waterborg CEJ, Arntz OJ, Kracht M, et al. (2013) Intravenous Delivery of HIV-Based Lentiviral Vectors Preferentially Transduces F4/80+ and Ly-6C+ Cells in Spleen, Important Target Cells in Autoimmune Arthritis. PLoS ONE 8(2): e55356. doi:10.1371/journal.pone.0055356 Editor: Nathalie Labrecque, Maisonneuve-Rosemont Hospital, Canada Received August 21, 2012; Accepted December 28, 2012; Published February 4, 2013 Copyright: ß 2013 van den Brand et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by: Top Institute Pharma, project D1-101; VIDI grant (917.46.363) from the Netherlands Organization for Scientific Research; and Dutch Arthritis Association (RF 11-1-409). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: a.vandeloo@reuma.umcn.nl Introduction Inflammatory diseases, such as rheumatoid arthritis, are characterized by infiltration of leukocytes into the inflamed tissue consisting of various immune cells from both the innate and adaptive immune system. Macrophages in arthritis have been extensively studied and play an important role in maintaining inflammation and joint destruction [1;2]. Moreover, a general approach of macrophage specific targeting with lipoplexes ameliorates experimental arthritis [3;4]. Specifically modulating macrophage activity during inflamma- tory conditions is a suitable approach to limit systemic side effects of treatment. In addition, gene therapy can be a powerful technique to achieve intracellular modulation of protein expres- sion or signaling. Effective gene therapeutic treatment of collagen- induced arthritis has been achieved by ectopic overexpression of suppressor of cytokine signaling 3 (SOCS3) in splenic antigen presenting cells (APCs) [5]. In addition, knock down of TNF receptor I by overexpression of a short hairpin was also effective in ameliorating experimental arthritis [6]. Both studies used adeno- viral vectors, ensuring a high, but transient transgene overexpres- sion. Over recent years, HIV based lentiviral vectors have been optimized regarding safety and production and proved to be a valuable tool in order to get long term transgene expression. Multiple studies have evaluated the feasibility of intravenous injection of lentivirus. These studies shown that the spleen is one of the organs predominantly targeted by lentivirus injected intrave- nously [7]. Further analysis on localization on GFP expression in the spleen showed large fluorescent clusters overlapping the marginal zone [8]. Cell surface markers revealed that mostly MHC-II positive cells were targeted by lentivirus [8;9], indicating preferential targeting of APCs by lentivirus. Specific targeting of APCs by lentivirus makes it possible to study the role of these APCs in inflammatory conditions. In addition, specific interference with gene expression can possibly PLOS ONE | www.plosone.org 1 February 2013 | Volume 8 | Issue 2 | e55356