Research paper Allergen immunotherapy with nanoparticles containing lipopolysaccharide from Brucella ovis Sara Gómez a , Carlos Gamazo a , Beatriz San Roman a , Marta Ferrer b , Maria Luisa Sanz b , Socorro Espuelas a , Juan M. Irache a, * a Departments of Pharmaceutical Technology and Microbiology, University of Navarra, Pamplona, Spain b Allergy Department, University Hospital of Navarra, Pamplona, Spain article info Article history: Received 22 October 2007 Accepted in revised form 21 May 2008 Available online 6 June 2008 Keywords: Nanoparticles Allergy Ovalbumin Adjuvant Lipopolysaccharide abstract The adjuvant and protective capacity against anaphylactic shock of the association between rough lipo- polysaccharide of Brucella ovis (LPS) coencapsulated with ovalbumin (OVA), as a model allergen, in Gan- trez Ò AN nanoparticles was investigated. Several strategies were performed in order to study the adjuvant effect of the LPS either encapsulated or coating the nanoparticles. OVA, as well as LPS, was incor- porated either during the manufacturing process (OVA-encapsulated or LPS-encapsulated nanoparticles, respectively) or after the preparation (OVA-coated or LPS-coated nanoparticles, respectively). After the administration of 10 lg of OVA incorporated in the different formulations, all the nanoparticles, with or without LPS, were capable of amplifying the immune response (IgG 1 and IgG 2a ). However, in a model of sensitized mice to OVA, the formulation with OVA and LPS-entrapped inside the nanoparticles admin- istered intradermally in three doses of 3 lg of OVA each was the only treatment that totally protected the mice from death after a challenge with an intraperitoneal injection of OVA. In contrast, the control group administered with OVA adsorbed onto a commercial alhydrogel adjuvant showed 80% mortality. These results are highly suggestive for the valuable use of Gantrez Ò nanoparticles combined with rough LPS of B. ovis in immunotherapy. Ó 2008 Elsevier B.V. All rights reserved. 1. Introduction Allergy, or hypersensitivity type I, applies to an abnormal reac- tion against innocuous environmental compounds (allergens) and involves complex interactions between exogenous and genetically determined factors. The development of allergen-specific IgE is clo- sely linked to allergen-specific T helper cell responses, character- ised by a predominant production of type-2 cytokine, as it is seen at sites of acute allergic inflammations [1]. The prevalence of type I allergies has constantly increased within recent years. Concretely, the European Academy of Allergology and Clinical Immunology organisation affirms that, in EU countries, allergic dis- ease is the most common chronic illness of childhood, affecting more than one child in four in some countries [2]. On the other hand, Arbes et al. found that 54.3% of the United States population, aged 6–59 years, had a positive allergy skin test to at least one of 10 common allergens [3]. Nowadays, the only effective ‘‘treat- ment” to cure allergy is specific immunotherapy (SIT). SIT involves repeated administrations of the sensitizing aller- gen, usually by subcutaneous injection or, more recently, by sub- lingual application. SIT has been shown to be a robust and clinically effective approach [4,5], improving the quality of life of the treated individuals, through the reduction of symptoms and medication usage [6]. However, historically, variability in safety and clinical efficacy has limited the widespread application of SIT [7]. Many strategies have been proposed in an attempt to solve these drawbacks, including the use of recombinant allergens and allergen derivatives [8], peptides containing aminoacid sequences of allergen T-cell epitopes [9], low molecular weight fractions of allergen extracts [10], mimotopes [11] and DNA vaccines [12]. The SIT drawbacks could also be overcome by the use of appro- priate adjuvants in order to decrease the administered allergen dose and to promote the adequate immune response [13]. In this context, we have demonstrated in previous studies the adjuvant capacity of Gantrez Ò nanoparticles, which can effectively enhance the immune response when administered by intradermal route [14]. However, this effect may be improved and or modulated by the incorporation of a PAMP (pathogen-associated molecular pat- tern) to nanoparticles. The dendritic cells (DCs) are antigen presenting cells (APCs) in- volved in initiating, directing, and controlling both innate and 0939-6411/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.ejpb.2008.05.016 * Corresponding author. Centro Galénico, University of Navarra, Ap. 177, 31080 Pamplona, Spain. Tel.: +34 948 425600; fax: +34 948 425649. E-mail address: jmirache@unav.es (J.M. Irache). European Journal of Pharmaceutics and Biopharmaceutics 70 (2008) 711–717 Contents lists available at ScienceDirect European Journal of Pharmaceutics and Biopharmaceutics journal homepage: www.elsevier.com/locate/ejpb