title: AQP1 and AQP3, psoriasin, and nitric oxide synthases 1-3 are inflammatory mediators in erythema toxicum neonatorum.
abstract: Erythema toxicum neonatorum is a common, inflammatory skin reaction in healthy newborn infants characterized by an accumulation of activated immune cells in the lesions. Its etiology and physiologic significance are still unclear. The purpose of this study was to extend the search for possible inflammatory mediators of the rash. We performed immunohistochemistry on punch biopsy cryosections from lesions of four, 1-day-old infants and from four matched controls without rash, using antibodies against the water channel proteins aquaporin-1 (AQP1) and aquaporin-3 (AQP3), psoriasin, and the nitric oxide synthase (NOS) enzymes, neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS). All sections from the lesions showed a dense, nodular cellular infiltrate located near the hair follicle. The vessels in the dermis showed a high incidence of AQP1 and eNOS. Strong staining for AQP1, AQP3, and psoriasin, as well as nNOS, iNOS, and eNOS were seen in the entire epidermal layer. The infiltrate in the dermis contained numerous cells expressing AQP1, AQP3, nNOS, iNOS, and eNOS. Double immunofluorescence staining showed that AQP3 was located in CD1a-expressing Langerhans cells and other dendritic cells in the dermis, as well as in CD14-expressing macrophages, CD15-expressing neutrophils, and EG2-expressing eosinophils surrounding the hair follicle. Our findings show that AQP1 and AQP3, psoriasin, and NOSs are involved in the activation of the skin immune system at birth.
authors.affiliation: Department of Woman and Child Health, Astrid Lindgren Children's Hospital Karolinska Institutet, Stockholm, Sweden. giovanna.marchini@ks.se
authors.forename: Giovanna
authors.initials: G
authors.lastname: Marchini
authors.forename: Berit
authors.initials: B
authors.lastname: Ståbi
authors.forename: Kanchana
authors.initials: K
authors.lastname: Kankes
authors.forename: Solbritt
authors.initials: S
authors.lastname: Lonne-Rahm
authors.forename: Morten
authors.initials: M
authors.lastname: Østergaard
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
mesh_terms: D051398:Aquaporin 1; D051400:Aquaporin 3; D020346:Aquaporins / Q000378:metabolism*; D001789:Blood Group Antigens; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D004890:Erythema / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007231:Infant, Newborn; D018836:Inflammation Mediators / Q000378:metabolism*; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; D012867:Skin / Q000737:chemistry* / Q000473:pathology
chemical_list: C496020:AQP1 protein, human; C496027:AQP3 protein, human; D020346:Aquaporins; D001789:Blood Group Antigens; D002135:Calcium-Binding Proteins; D018836:Inflammation Mediators; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; C089242:S100A7 protein, human; D051398:Aquaporin 1; D051400:Aquaporin 3; D019001:Nitric Oxide Synthase