title: Overexpression of tumour necrosis factor-alpha-converting enzyme in psoriasis.
abstract: BACKGROUND
  Tumour necrosis factor (TNF)-alpha-converting enzyme (TACE) is a metalloproteinase-disintegrin that releases soluble TNF-alpha from cells by cleaving within the extracellular domain of membrane-bound pro-TNF-alpha. It was proposed that TNF-alpha is involved in the pathogenesis of psoriasis, and it is therefore suggested that TACE has important roles in psoriasis. However, it is unclear whether TACE is expressed in psoriatic tissue.
  
  
  OBJECTIVE
  To clarify whether TACE is expressed in psoriatic lesions and whether expression levels of TACE mRNA are increased in lesional compared with nonlesional psoriatic skin.
  
  
  METHODS
  Skin biopsies were obtained from patients with psoriasis. We examined the expression of TACE in psoriatic tissues using a novel real-time quantitative reverse transcriptase-polymerase chain reaction method and immunohistochemical analysis.
  
  
  RESULTS
  There was a significant rise in the level of TACE mRNA expression in lesional psoriatic skin compared with nonlesional skin in all patients. There was a statistically significant rise in the level of TACE mRNA expression in lesional psoriatic skin compared with nonlesional skin (mean +/- SD TACE/glyceraldehyde-3-phosphate dehydrogenase ratio 0.031 +/- 0.012 vs. 0.009 +/- 0.002, P < 0.05). In lesional psoriatic skin, immunostaining with anti-TACE antibody was present throughout all layers of the epidermis. TACE immunostaining was found in the cytoplasm of keratinocytes. There was staining associated with blood vessels in the papillary dermis and perivascular inflammatory cells. In particular, mast cells showed strong staining. They contained numerous granules that were stained for TACE in the cytoplasm.
  
  
  CONCLUSIONS
  The findings of the present study suggest that elevation of TACE mRNA in psoriatic lesions is due to many cells, particularly mast cells, that function in lesional psoriatic skin as an important source of TNF-alpha and other cytokines.
authors.affiliation: Department of Dermatology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Mitsuhashi
authors.forename: S
authors.initials: S
authors.lastname: Kondo
mesh_terms: D051722:ADAM Proteins; D000072198:ADAM17 Protein; D002478:Cells, Cultured; D015870:Gene Expression; D006801:Humans; D007124:Immunoenzyme Techniques; D015603:Keratinocytes / Q000201:enzymology; D008666:Metalloendopeptidases / Q000096:biosynthesis* / Q000235:genetics; D011565:Psoriasis / Q000201:enzymology*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
chemical_list: D012333:RNA, Messenger; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human