title: Nano-TiO2 modulates the dermal sensitization potency of dinitrochlorobenzene after topical exposure.
abstract: BACKGROUND
  Little is known about the impact of engineered nanoparticles (ENPs) on skin sensitization caused by chemicals.
  
  
  OBJECTIVE
  We determined the ability of different ENPs (TiO2 , Ag and SiO2 ) and aged paint particles containing ENPs to modulate dermal sensitization by a known potent dermal sensitizer.
  
  
  METHODS
  The fur of BALB/c mice in the area around the ears was cut with scissors 1 day prior to topical exposure to ENPs (0·4, 4 or 40 mg mL(-1) ), paint particles containing ENPs (4 mg mL(-1) ) or vehicle (day 0). On days 1, 2 and 3, the mice received dermal applications on the back of both ears of 2,4-dinitrochlorobenzene (DNCB) or vehicle. The stimulation index (SI) was calculated on day 6.
  
  
  RESULTS
  Topical exposure to TiO2 , Ag or SiO2 ENPs, or aged paint particles followed by vehicle treatment as a control, did not influence the SI. When 4 mg mL(-1) TiO2 ENPs were applied prior to DNCB sensitization, we found an increased SI compared with vehicle-exposed mice prior to DNCB sensitization. Furthermore, an increased titanium concentration was found in the draining lymph node cells of this group. Topical exposure to Ag or SiO2 ENPs or aged paint particles prior to DNCB sensitization did not influence the SI.
  
  
  CONCLUSIONS
  We have demonstrated that topical exposure to TiO2 ENPs increases chemical-induced dermal sensitization.
authors: Center for Environment and Health, KU Leuven, B-3000, Leuven, Belgium.
authors: S
authors: S
authors: Smulders
authors: L
authors: L
authors: Golanski
authors: E
authors: E
authors: Smolders
authors: J
authors: J
authors: Vanoirbeek
authors: P H M
authors: PH
authors: Hoet
mesh_terms: D000279:Administration, Cutaneous; D000485:Allergens / Q000494:pharmacology; D000818:Animals; D017449:Dermatitis, Allergic Contact / Q000209:etiology; D004137:Dinitrochlorobenzene / Q000633:toxicity*; D007509:Irritants / Q000633:toxicity*; D008297:Male; D053768:Metal Nanoparticles / Q000008:administration & dosage; D008807:Mice, Inbred BALB C; D053758:Nanoparticles / Q000008:administration & dosage*; D010150:Paint; D012822:Silicon Dioxide / Q000494:pharmacology; D012867:Skin / Q000187:drug effects; D014025:Titanium / Q000494:pharmacology*
chemical_list: D000485:Allergens; D004137:Dinitrochlorobenzene; D007509:Irritants; C009495:titanium dioxide; D012822:Silicon Dioxide; D014025:Titanium