title: AHAPS-functionalized silica nanoparticles do not modulate allergic contact dermatitis in mice.
abstract: Allergic contact dermatitis (ACD) is a common skin disease in people and may become a potential site of exposure to nanoparticles (NP). Silica nanoparticles (SiO2-NP) possess a promising potential for various medical and non-medical applications, including normal and diseased skin as target organs. However, it has been shown that negatively charged SiO2-NP may act as proinflammatory adjuvant in allergic diseases. The effect of topical SiO2-NP exposure on preexisting ACD has not been studied to date although this reflects a common in vivo situation. Of particular interest are the potential effects of positively charged N-(6-aminohexyl)-aminopropyltrimethoxysilane (AHAPS)-functionalized SiO2-NP which are promising candidates for delivery systems, including gene delivery into the skin. Here, the effects of such AHAPS-functionalized SiO2-NP (55 ± 6 nm in diameter) were studied in an oxazolone-induced ACD model in SKH1 mice and compared to ACD mice treated with vehicle only. The clinical course of the disease was assessed by monitoring of the transepidermal water loss (TEWL) and the erythema. In histologic and morphometric analyses, the distribution of particles, the degree of inflammation, epidermal thickness, and the inflammatory infiltrate were characterized and quantified by standard and special histological stains as well as immunohistochemistry for CD3+ lymphocytes. To assess possible systemic effects, serum immunoglobulin E (IgE) was determined by enzyme-linked immunosorbent assay. Following administration of AHAPS-SiO2-NP for five consecutive days, no effects were observed in all clinical, histologic, morphometric, and molecular parameters investigated. In conclusion, positively charged AHAPS-SiO2-NP seem not to affect the course of ACD during exposure for 5 days.
authors.affiliation: Institute of Veterinary Pathology, Freie Universität Berlin, Robert-von-Ostertag-Str. 15, 14163 Berlin, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Ostrowski
authors.affiliation: Institute of Chemistry and Biochemistry - Physical and Theoretical Chemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Nordmeyer
authors.affiliation: Institute of Veterinary Pathology, Freie Universität Berlin, Robert-von-Ostertag-Str. 15, 14163 Berlin, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Mundhenk
authors.affiliation: Department of Dermatology, Venerology and Allergology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Joachim W
authors.initials: JW
authors.lastname: Fluhr
authors.affiliation: Department of Dermatology, Venerology and Allergology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lademann
authors.affiliation: Institute of Chemistry and Biochemistry - Physical and Theoretical Chemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Graf
authors.affiliation: Institute of Chemistry and Biochemistry - Physical and Theoretical Chemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
authors.forename: Eckart
authors.initials: E
authors.lastname: Rühl
authors.affiliation: Institute of Veterinary Pathology, Freie Universität Berlin, Robert-von-Ostertag-Str. 15, 14163 Berlin, Germany.
authors.forename: Achim D
authors.initials: AD
authors.lastname: Gruber
keywords: Allergic contact dermatitis; Mouse model; Oxazolone; Silica nanoparticles; Toxicopathology