1. ¹Neuroimmunology Unit, San Raffaele Scientific Institute, Milan, Italy
2. ²Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy
3. ³Neurological Department, San Raffaele Scientific Institute, Milan, Italy
4. ⁴Molmed s.p.a., Milan, Italy

Correspondence: Dr R Furlan, Neuroimmunology Unit, San Raffaele Scientific Institute, Via Olgettina 58, Milan 20132, Italy. E-mail: furlan.roberto@hsr.it

⁵These authors contributed equally to this work.

Received 23 July 2007; Revised 6 November 2007; Accepted 21 December 2007; Published online 31 January 2008.

Abstract

Central nervous system (CNS) delivery of anti-inflammatory cytokines, such as interleukin 4 (IL4), holds promise as treatment for multiple sclerosis (MS). We have previously shown that short-term herpes simplex virus type 1-mediated IL4 gene therapy is able to inhibit experimental autoimmune encephalomyelitis (EAE), an animal model of MS, in mice and non-human primates. Here, we show that a single administration of an IL4-expressing helper-dependent adenoviral vector (HD-Ad) into the cerebrospinal fluid (CSF) circulation of immunocompetent mice allows persistent transduction of neuroepithelial cells and long-term (up to 5 months) CNS transgene expression without toxicity. Mice affected by chronic and relapsing EAE display clinical and neurophysiological recovery from the disease once injected with the IL4-expressing HD-Ad vector. The therapeutic effect is due to the ability of IL4 to increase, in inflamed CNS areas, chemokines (CCL1, CCL17 and CCL22) capable of recruiting regulatory T cells (CD4⁺CD69^-CD25⁺Foxp3⁺) with suppressant functions. CSF delivery of HD-Ad vectors expressing anti-inflammatory molecules might represent a valuable therapeutic option for CNS inflammatory disorders.