Glutathione and catalase suppress TGFbeta-induced cataract-related changes in cultured rat lenses and lens epithelial explants.
OBJECTIVE
The damaging effects of oxidative stress and transforming growth factor-beta (TGFbeta)-induced transdifferentiation of lens epithelial cells have both been implicated independently in the etiology of cataract. The aim of this study was to investigate whether the presence of antioxidant systems in the lens influences the ability of lens epithelial cells to respond to TGFbeta.


METHODS
Whole lenses from young rats were cultured with or without TGFbeta in the presence or absence of reduced glutathione (GSH). Lens epithelial explants from weanling rats were used to investigate the effects of GSH and catalase on TGFbeta-induced cataract-related changes. Lenses were monitored for opacification for three to four days, photographed, and then processed for routine histology. Explants were assessed by phase contrast microscopy, enzyme-linked immunosorbent assay (ELISA) of alpha-smooth muscle actin (alphaSMA), and/or immunolocalization of alphaSMA and Pax6, markers for transdifferentiation and normal lens epithelial phenotype, respectively.


RESULTS
In cultured lenses, GSH strongly suppressed TGFbeta-induced opacification and subcapsular plaque formation. In explants, both GSH and catalase suppressed changes typically associated with TGFbeta-induced transdifferentiation including wrinkling of the lens capsule, cell-surface blebbing, apoptotic cell loss, induction of alphaSMA, and loss of Pax6 expression.


CONCLUSIONS
This study suggests that antioxidant systems present in the normal lens, which protect the epithelium against the damaging effects of reactive oxygen species, may also serve to protect it against the potentially cataractogenic effects of TGFbeta. Taken together with other recent studies, it also raises the possibility that TGFbeta may induce cataract-related changes in lens epithelial cells via release of hydrogen peroxide.
School of Medical Sciences (Anatomy and Histology) and Bosch Institute, University of Sydney, Sydney, NSW, Australia. coralcha@anatomy.usyd.edu.au
Coral G
CG
Chamberlain
Kylie J
KJ
Mansfield
Anna
A
Cerra
D000199:Actins / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D002374:Catalase / Q000378:metabolism*; D002386:Cataract / Q000378:metabolism* / Q000473:pathology*; D002454:Cell Differentiation; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D005136:Eye Proteins / Q000378:metabolism; D015870:Gene Expression; D005978:Glutathione / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000378:metabolism; D007908:Lens, Crystalline / Q000473:pathology*; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D018384:Oxidative Stress; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism; D051381:Rats; D012097:Repressor Proteins / Q000378:metabolism; D046509:Tissue Culture Techniques; D016212:Transforming Growth Factor beta / Q000378:metabolism*
C558396:Acta2 protein, mouse; D000199:Actins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; C000605733:Pax6 protein, rat; D012097:Repressor Proteins; D016212:Transforming Growth Factor beta; D002374:Catalase; D005978:Glutathione