Altered expression of growth factors and cytokines in keratoconus, bullous keratopathy and diabetic human corneas

Exp Eye Res. 2001 Aug;73(2):179-89. doi: 10.1006/exer.2001.1028.


The purpose of this study was to identify the growth factors and cytokines present in normal and diseased corneas. Total RNA was isolated from normal and diseased corneas. cDNA was synthesized from individual corneas and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was performed with primers to IL-1alpha, 1IL-8, PDGF-B, BMP-2, BMP-4, IGF-I, TGF-beta2, FGF-2, and VEGF. After normalization to beta2-microglobulin, several factors were identified that were significantly different from normal. Antibodies to IGF-I, BMP-2, VEGF and TGF-beta2 were used for immunohistochemistry. A total of 93 corneas were used for this study including 31 normal, 20 keratoconus, 19 bullous keratopathy (pseudophakic and aphakic, PBK/ABK), and 23 diabetic corneas. The VEGF RNA levels were significantly decreased in the keratoconus and PBK/ABK corneas but increased in the diabetic corneas. BMP-2 gene expression was lower than normal in the PBK/ABK and diabetic corneas. IGF-I and BMP-4 RNA levels were increased in PBK/ABK. In the immunohistochemical studies, the protein patterns paralleled those found at the mRNA level. The only exception was IGF-I in diabetic corneas that showed increased staining in the epithelium and its basement membrane without a significant increase in mRNA levels. TGF-beta2 mRNA and protein levels were similar to normal in all diseased corneas. Thus, no alterations in the tested growth factors/cytokines were unique to keratoconus corneas. In contrast, PBK/ABK corneas had specific significant elevations of BMP-4 and IGF-I. Diabetic corneas were unique in their increased VEGF mRNA levels. These data suggest that while some growth factor/cytokine alterations are non-specific and can be found in multiple corneal diseases, there are others that are unique to that disease.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Bone Morphogenetic Protein 2
  • Bone Morphogenetic Protein 4
  • Bone Morphogenetic Proteins / analysis
  • Bone Morphogenetic Proteins / metabolism
  • Case-Control Studies
  • Corneal Diseases / etiology
  • Corneal Diseases / metabolism*
  • Cytokines / metabolism*
  • DNA, Complementary / analysis
  • Diabetes Complications
  • Diabetes Mellitus / metabolism*
  • Endothelial Growth Factors / analysis
  • Endothelial Growth Factors / metabolism
  • Fibroblast Growth Factors / metabolism
  • Gene Expression
  • Growth Substances / metabolism*
  • Humans
  • Insulin-Like Growth Factor I / analysis
  • Insulin-Like Growth Factor I / metabolism
  • Interleukin-1 / analysis
  • Interleukin-1 / metabolism
  • Interleukin-8 / analysis
  • Interleukin-8 / metabolism
  • Keratoconus / metabolism
  • Platelet-Derived Growth Factor / analysis
  • Platelet-Derived Growth Factor / metabolism
  • RNA / analysis
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transforming Growth Factor beta / analysis
  • Transforming Growth Factor beta / metabolism


  • BMP2 protein, human
  • BMP4 protein, human
  • Bone Morphogenetic Protein 2
  • Bone Morphogenetic Protein 4
  • Bone Morphogenetic Proteins
  • Cytokines
  • DNA, Complementary
  • Endothelial Growth Factors
  • Growth Substances
  • Interleukin-1
  • Interleukin-8
  • Platelet-Derived Growth Factor
  • Transforming Growth Factor beta
  • Fibroblast Growth Factors
  • RNA
  • Insulin-Like Growth Factor I