title: Immunohistochemical expression of matrix metalloproteinases in photodamaged skin by photodynamic therapy.
abstract: BACKGROUND
  Photodynamic therapy (PDT) has been described for photoageing treatment, but its mechanism of action is not clarified. Although PDT-induced matrix metalloproteinase (MMP) expression and collagen production have been studied in normal skin and in inflammatory disease, there is no report about the effect of PDT on the extracellular matrix in photodamaged skin.
  
  
  OBJECTIVE
  To evaluate skin remodelling induced by methyl aminolaevulinate (MAL)-PDT in photodamaged skin by histological and immunohistochemical studies.
  
  
  METHODS
  Fourteen patients were treated with two sessions of MAL-PDT. The light source was a light-emitting diode (635 nm, 37 J cm(-2)). Skin biopsies were performed in all patients before and at 3 and 6 months after treatment. Immunohistochemical studies evaluated collagen types I and III, MMP-1, MMP-3, MMP-7, MMP-9, MMP-12 and tissue inhibitor of metalloproteinases-1.
  
  
  RESULTS
  Global improvement in photodamaged skin was observed. A significant increase in expression of MMP-9 in the dermis was detected at 3 months after treatment (P = 0.002). Significant increases in the expression of collagen type I at 3 months (P = 0.002) and at 6 months after treatment (P = 0.001) were also observed.
  
  
  CONCLUSIONS
  Skin remodelling induced by MAL-PDT was demonstrated in photodamaged skin. Two sessions of MAL-PDT increases immunohistochemical expression of MMP-9 in the dermis at 3 months after treatment, and also of collagen type I.
authors.affiliation: Department of Dermatology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. mariaclaudia@predialnet.com.br
authors.forename: M C
authors.initials: MC
authors.lastname: Almeida Issa
authors.forename: J
authors.initials: J
authors.lastname: Piñeiro-Maceira
authors.forename: R E
authors.initials: RE
authors.lastname: Farias
authors.forename: M
authors.initials: M
authors.lastname: Pureza
authors.forename: R
authors.initials: R
authors.lastname: Raggio Luiz
authors.forename: M
authors.initials: M
authors.lastname: Manela-Azulay
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D024042:Collagen Type I / Q000378:metabolism; D024061:Collagen Type III / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D028022:Low-Level Light Therapy; D008297:Male; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D008875:Middle Aged; D010778:Photochemotherapy / Q000379:methods; D017319:Photosensitizing Agents / Q000627:therapeutic use; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D015595:Skin Aging / Q000187:drug effects / Q000473:pathology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D017319:Photosensitizing Agents; D019715:Tissue Inhibitor of Metalloproteinase-1; C475457:methyl 5-aminolevulinate; D000622:Aminolevulinic Acid; D020782:Matrix Metalloproteinases