title: Multiple tissue kallikrein mRNA and protein expression in normal skin and skin diseases.
abstract: BACKGROUND
  Human tissue kallikreins are a gene family (KLK1-KLK15) encoding for 15 secretory serine proteases (hK1-hK15). Two tissue kallikrein proteins, hK5 and hK7, were previously found in the stratum corneum (SC), stratum granulosum (SG) and appendages. hK8 was also shown to be secreted via lamellar granules and numerous KLK mRNAs were previously identified. KLKs are believed to be responsible for desquamation of corneocytes and sebum, sweat and hair maturation.
  
  
  OBJECTIVE
  To demonstrate immunohistochemically the expression of hK6, hK8 and hK13 in normal skin tissue and to show an increased cell number expressing kallikrein mRNAs and proteins in psoriasis vulgaris (PV) and atopic dermatitis (AD).
  
  
  METHODS
  Samples of normal, PV and AD skin were obtained. hK6-, hK8- and hK13-specific antibodies were produced and used for immunohistochemical analysis. Multiple KLK mRNAs were synthesized and used for in situ hybridization study.
  
  
  RESULTS
  Three other hKs, namely hK6, hK8 and hK13, were immunohistochemically identified as new skin serine proteases in the whole SC, SG, sebaceous glands, eccrine sweat glands, hair follicles and nerves. We also demonstrated an increased number of cells expressing KLK mRNAs and hKs in PV and AD. In PV, KLK mRNAs/hKs were predominantly expressed in the upper epidermis. In AD, hK distribution was rather diffuse and expanded into the lower epidermis.
  
  
  CONCLUSIONS
  The colocalization of various hKs seems to be essential for the regulation of serine protease activity in skin and for steady desquamation and skin barrier function. Moreover, the increased number of cells expressing multiple KLK mRNA and hK in PV and AD could be a clue to elucidate their pathogenesis.
authors.affiliation: Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, Canada, M5G 1X5.
authors.forename: N
authors.initials: N
authors.lastname: Komatsu
authors.forename: K
authors.initials: K
authors.lastname: Saijoh
authors.forename: T
authors.initials: T
authors.lastname: Toyama
authors.forename: R
authors.initials: R
authors.lastname: Ohka
authors.forename: N
authors.initials: N
authors.lastname: Otsuki
authors.forename: G
authors.initials: G
authors.lastname: Hussack
authors.forename: K
authors.initials: K
authors.lastname: Takehara
authors.forename: E P
authors.initials: EP
authors.lastname: Diamandis
mesh_terms: D000328:Adult; D000918:Antibody Specificity / Q000276:immunology; D015153:Blotting, Western / Q000379:methods; D003876:Dermatitis, Atopic / Q000276:immunology / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D007610:Kallikreins / Q000032:analysis; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis*; D012867:Skin / Q000737:chemistry* / Q000276:immunology; D020840:Tissue Kallikreins / Q000032:analysis*
chemical_list: D012333:RNA, Messenger; C470778:KLK13 protein, human; C103551:KLK6 protein, human; C094799:KLK8 protein, human; D007610:Kallikreins; D020840:Tissue Kallikreins