title: Mode of action of intranasal corticosteroids.
abstract: The mode of action of intranasal corticosteroids (INCS) is complex. It is not known whether INCS penetrate the nasal mucosa or act on target cells; however, their low systemic activity supports the concept of local action on nasal mucosa. This local effect can nonetheless influence a variety of inflammatory cells and their mediators such as epithelial cells, lymphocytes, basophils, mast cells, and Langerhans cells. Corticosteroid-induced inhibition of immunoglobulin E-dependent release of histamine is a possible but unproven mode of action. Epithelial cells are an important target for corticosteroids, and INCS concentration is high at the epithelial surface. INCS may combine with the corticosteroid receptors in epithelial cells, which are then expelled into the airway lumen together with the dead epithelial cells or migrating inflammatory cells. A reduced influx of mediator cells may explain some of the effects of INCS on rhinitis symptoms, but it cannot explain all of the effects because INCS also reduce the early-phase sneezing and rhinorrhea after an allergen challenge outside the pollen season. In this situation, the number of surface mast cells/basophils is very low, as it is in the absence of allergic rhinitis. The mechanism by which INCS treatment of allergic rhinitis reduces itching, sneezing, and rhinorrhea, the characteristic symptoms of an early-phase response involving mast cell release of histamine, remains to be determined. Studies should be conducted to characterize the broad range of mechanisms by which INCS produce their therapeutic effects in allergic rhinitis.
authors.affiliation: Department of Respiratory Diseases, Aarhus University Hospital, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Mygind
authors.forename: L P
authors.initials: LP
authors.lastname: Nielsen
authors.forename: H J
authors.initials: HJ
authors.lastname: Hoffmann
authors.forename: A
authors.initials: A
authors.lastname: Shukla
authors.forename: G
authors.initials: G
authors.lastname: Blumberga
authors.forename: R
authors.initials: R
authors.lastname: Dahl
authors.forename: H
authors.initials: H
authors.lastname: Jacobi
mesh_terms: D000281:Administration, Intranasal; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use*; D018926:Anti-Allergic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001491:Basophils / Q000276:immunology; D004804:Eosinophils / Q000276:immunology; D006801:Humans; D007801:Langerhans Cells / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology; D008407:Mast Cells / Q000276:immunology; D009297:Nasal Mucosa / Q000187:drug effects* / Q000276:immunology / Q000503:physiopathology; D012221:Rhinitis, Allergic, Perennial / Q000188:drug therapy* / Q000503:physiopathology; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy* / Q000503:physiopathology; D013256:Steroids; D013997:Time Factors
chemical_list: D000305:Adrenal Cortex Hormones; D018926:Anti-Allergic Agents; D000893:Anti-Inflammatory Agents; D013256:Steroids