toxicity, as demonstrated by healthy regenerated hairs post-grafting. Animals were handled according to the guidelines of Institutional Animal Care and Use Committee at Cincinnati Children’s Hospital. CONFLICT OF INTEREST The authors state no conflict of interest. Penkanok Sriwiriyanont 1 , Akira Hachiya 2,3 , William L. Pickens 1 , Shigeru Moriwaki 2 , Atsushi Ohuchi 2 , Takashi Kitahara 2 , Yoshinori Takema 2 , William J. Kitzmiller 1,4 , Marty O. Visscher 1 , Alexander Bello 5 , Ryoji Tsuboi 3 and Gary P. Kobinger 5 1 Skin Sciences Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA; 2 Kao Biological Science Laboratories, Haga, Tochigi, Japan; 3 Department of Dermatology, Tokyo Medical University, Tokyo, Japan; 4 Department of Surgery, University of Cincinnati, Cincinnati, OH, USA; 5 Special Pathogens Program, Department of Medical Microbiology, National Microbiology Laboratory, Public Health Agency of Canada, University of Manitoba, Winnipeg, Canada E-mail: gary_kobinger@phac-aspc.gc.ca REFERENCES Croyle MA, Callahan SM, Auricchio A, Schumer G, Linse KD, Wilson JM et al. (2004) PEGylation of a vesicular stomatitis virus G pseudotyped lentivirus vector prevents inac- tivation in serum. J Virol 78:912–21 Emerman M (2000) Learning from leniviruses. Nat Genet 24:8–9 Gagnoux-Palacios L, Hervouet C, Spirito F, Roques S, Mezzina M, Danos O et al. (2005) Assessment of optimal transduction of primary human skin keratinocytes by viral vector. J Gene med 7:1178–86 Ghazizadeh S, Kalish RS, Taichman LB (2003) Immune-mediated loss of transgene expres- sion in skin: implications for cutaneous gene therapy. Mol Ther 7:296–303 Gown AM, Vogel AM, Hoak D, Gouch F, McNutt MA (1986) Monoclonal antibodies specific for melanocytic tumors distinguish subpopu- lations of melanocytes. Am J Pathol 123:195–203 Hachiya A, Sriwiriyanont P, Patel A, Saito N, Ohuchi A, Kitahara T et al. (2007) Gene transfer in human skin with different pseudo- typed HIV-based vectors. Gene Therapy 14:648–56 Hashimoto T, Kazama T, Ito M, Urano K, Katakai Y, Yamaguchi N et al. (2000) Histologic and cell kinetic studies of hair loss and subse- quent recovery process of human scalp hair follicles grafted onto severe combined im- munodeficient mice. J Invest Dermatol 115:200–6 Hashimoto T, Kazama T, Ito M, Urano K, Katakai Y, Yamaguchi N et al. (2001) Histologic study of the regeneration process of human hair follicles grafted onto SCID mice after bulb amputation. J Investig Dermatol Symp Proc 6:38–42 Kobinger GP, Weiner DJ, Yu QC, Wilson JM (2001) Filovirus-pseudotyped lentiviral vec- tor can efficiently and stably transduce airway epithelia in vivo. Nat Biotechnol 19:225–30 Naldini L, Blomer U, Gage FH, Trono D, Verma IM (1996) Efficient transfer, integration, and sustained long-term expression of the trans- gene in adult rat brains injected with a lentiviral vector. Proc Natl Acad Sci USA 93:11382–8 Okimoto MA, Fan H (1999) Moloney murine leukemia virus infects cells of the developing hair follicle after neonatal subcutaneous inoculation in mice. J Virol 73:2509–16 Philpott MP, Green MR, Kealey T (1990) Human hair growth in vitro. J Cell Sci 97: 463–71 Rohr UP, Kronenwett R, Grimm D, Kleinschmidt J, Haas R (2002) Primary human cells differ in their susceptibility to rAAV-2- mediated gene transfer and duration of reporter gene expression. J Virol Methods 105:265–75 Sharov A, Tobin DJ, Sharova TY, Atoyan R, Botchkarev VA (2005) Changes in different melanocyte populations during hair follicle involution (catagen). J Invest Derm 125:1259–67 Stark HJ, Breitkreutz D, Limat A, Bowden P, Fusenig NE (1987) Keratins of the human hair follicle: ‘‘hyperproliferative’’ keratins consis- tently expressed in outer root sheath cells in vivo and in vitro. Differentiation 35:236–48 Sugiyama-nakagiri Y, Akiyama M, Shimizu H (2006) Hair follicle stem cell-targeted gene transfer and reconstitution system. Gene Therapy 13:732–7 Szilvassy SJ, Corry S (1994) Efficient retroviral gene transfer to purified long-term repopulat- ing hematopoietic stem cells. Blood 84:74–83 Szilvassy SJ, Fraser CC, Eaves CJ, Lansdrop PM, Eaves AC, Humphries RK (1989) Retrovirus- mediated gene transfer to purified hemopoie- tic stem cells with long-term lympho-myelo- poietic repopulating ability. Proc Natl Acad Sci USA 86:8798–802 Zhao M, Saito N, LI L, Baranov E, Kondoh H, Mishima Y et al. (2000) A novel approach to gene therapy of albino hair in histoculture with a retroviral streptomyces tyrosinase gene. Pigment Cell Res 13:345–51 Double-Blind, Placebo-Controlled, Dose-Escalation Study to Evaluate the Pharmacologic Effect of CP-690,550 in Patients With Psoriasis Journal of Investigative Dermatology(2009) 129, 2299–2302; doi:10.1038/jid.2009.25; published online 19 February 2009 TO THE EDITOR Aberrant activation of the cellular im- mune system is recognized as the driving pathogenic event of psoriasis (Krueger and Bowcock 2005), con- firmed by an infiltration of T-cells into psoriatic lesions (Gudjonsson et al 2004). Inhibition of Janus kinase 3 (JAK3) in T cells is expected to un- couple early T-cell receptor-triggered signaling from downstream events (Pesu et al 2005) and, for this reason, JAK3 inhibitors could be effective in T-cell-mediated disorders such as psori- asis. CP-690,550 is an orally active highly selective JAK inhibitor and Abbreviations: AE, adverse events; b.i.d., two times-daily dosing; IL, interleukin; JAK, Janus kinase; K16, keratin 16; LSM, least squares mean; PGA, Physician’s Global Assessment (of Psoriasis); PLSS, Psoriatic Lesion Severity Sum; q.d., once-daily dosing; SD, standard deviation; SE, standard error www.jidonline.org 2299 MG Boy et al. CP-690,550 Dose Escalation in Psoriasis