title: Lichen planopilaris and pseudopelade of Brocq involve distinct disease associated gene expression patterns by microarray.
abstract: BACKGROUND
  Lichen planopilaris (LPP) and pseudopelade of Brocq (PPB) are two scarring alopecia diagnoses that exhibit similar clinical features. Some suggest LPP and PPB are not distinct diseases, but rather different clinical presentations in a spectrum derived from the same underlying pathogenic mechanism.
  
  
  OBJECTIVE
  We explored the degree of similarity between LPP and PPB gene expression patterns and the potential for common and unique gene pathway and gene activity in LPP and PPB using microarrays.
  
  
  METHODS
  Microarray analysis, using a 21K cDNA set, was performed on pairs of biopsies obtained from affected and unaffected scalp of untreated patients. Diagnosis was confirmed by histopathology. Significantly differentially expressed genes were identified by analysis of microarray results in various datasets and screened for signaling pathway involvement. Selected genes were validated by quantitative PCR and immunohistology.
  
  
  RESULTS
  The global gene expression profiles in LPP and PPB versus comparative intra-control scalp tissue were distinguishable by significance analysis of microarrays (SAM). There was limited commonality in the gene expression profiles between LPP and PPB. Specific genes, such as MMP11, TNFSF13B, and APOL2, were identified with significantly differential expression in association with LPP versus PPB.
  
  
  CONCLUSIONS
  Our findings may have important implications for understanding the pathogenesis of LPP and PPB at the molecular level. Results suggest LPP and PPB involve different mechanisms of disease development and should be regarded as biologically distinct cicatricial alopecia diagnoses. Genes that we have identified may be useful as markers of the respective diagnoses and may be potential therapeutic targets.
authors.affiliation: Department of Dermatology and Skin Science, University of British Columbia, Vancouver, Canada.
authors.forename: Mei
authors.initials: M
authors.lastname: Yu
authors.forename: Robert H
authors.initials: RH
authors.lastname: Bell
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Ross
authors.forename: Blanche K K
authors.initials: BK
authors.lastname: Lo
authors.forename: Megan
authors.initials: M
authors.lastname: Isaac-Renton
authors.forename: Magda
authors.initials: M
authors.lastname: Martinka
authors.forename: Anne
authors.initials: A
authors.lastname: Haegert
authors.forename: Jerry
authors.initials: J
authors.lastname: Shapiro
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: McElwee
mesh_terms: D000505:Alopecia / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D001706:Biopsy; D016000:Cluster Analysis; D005189:False Positive Reactions; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D008010:Lichen Planus / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D016133:Polymerase Chain Reaction; D012535:Scalp / Q000473:pathology; D012867:Skin / Q000473:pathology