title: Transforming growth factor-β signaling pathway activation in Keratoconus.
abstract: OBJECTIVE
  To assess the presence of transforming growth factor-β (TGFβ) pathway markers in the epithelium of keratoconus patient corneas.
  
  
  METHODS
  Retrospective, comparative case series of laboratory specimens.
  
  
  METHODS
  Immunohistochemistry results for TGFβ2, total TGFβ, mothers against decacentaplegic homolog (Smad) 2, and phosphorylated Smad2 was performed on formalin-fixed, paraffin-embedded sections of keratoconus patient corneas and normal corneas from human autopsy eyes. Keratoconus patient corneas were divided in two groups, depending on their severity based on keratometer readings and pachymetry. Autopsy controls were age-matched with the keratoconus cases. Immunohistochemistry signal quantification was performed using automated software. Real-time reverse-transcriptase polymerase chain reaction was performed on total ribonucleic acid of epithelium of keratoconus patient corneas and autopsy control corneas.
  
  
  RESULTS
  Immunohistochemistry quantification showed a significant increase in mean signal in the group of severe keratoconus cases compared with normal corneas for TGFβ2 and phosphorylated Smad2 (P < .05). Immunohistochemistry analysis using antibodies against total TGFβ and Smad2 did not show any significant increase in the keratoconus cases versus the autopsy controls. Reverse-transcriptase polymerase chain reaction exhibited elevated messenger ribonucleic acid levels of Smad2 and TGFβ2 in severe keratoconus corneal epithelium.
  
  
  CONCLUSIONS
  This work shows increased TGFβ pathway markers in severe keratoconus cases and provides the rationale for investigating TGFβ signaling further in the pathophysiology of keratoconus.
authors.affiliation: Wilmer Eye Institute, The Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA.
authors.forename: Christoph
authors.initials: C
authors.lastname: Engler
authors.forename: Shukti
authors.initials: S
authors.lastname: Chakravarti
authors.forename: Jefferson
authors.initials: J
authors.lastname: Doyle
authors.forename: Charles G
authors.initials: CG
authors.lastname: Eberhart
authors.forename: Huan
authors.initials: H
authors.lastname: Meng
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Stark
authors.forename: Clare
authors.initials: C
authors.lastname: Kelliher
authors.forename: Albert S
authors.initials: AS
authors.lastname: Jun
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019573:Epithelium, Corneal / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007640:Keratoconus / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D053781:Transforming Growth Factor beta2 / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D016212:Transforming Growth Factor beta; D053781:Transforming Growth Factor beta2