Abstract
Purpose: :
TGF-β plays a relevant role in cell growth, differentiation and death. We investigated the expression of TGFß system (gene and receptors) in conjunctival epithelium of dry ye (DE) patients compared to that of healthy subjects.
Methods: :
Conjunctival impression cytology (CIC) samples were obtained from 48 DE patients (tear-deficient; Schirmer-1 < 5mm) and 69 healthy subjects (all of them>50 years old).Following RNA extraction and cDNA synthesis, real-time PCR was performed using specific primers to evaluate expression of the following genes: TGFß1, TGFß2, TGFß3 and the receptors TGFß-RI, TGFß-RII, and TGFß-RIII. A SYBR® Green I dye detection was used. A housekeeping gene (GAPDH) was amplified to normalize the amount of expression levels. No-template control and RNA were studied for testing contamination issues. Each sample was done in duplicate. A dissociation curve was performed to verify the identity of each gene amplification product. The results were analyzed applying the comparative Ct method using the data obtained from healthy subjects as calibrator. The student t-test for independent samples was used for statistical analysis.
Results: :
All genes were expressed in all samples. There were no differences in TGFß1, TGFß-RI and TGFß-RII expression between DE patients and controls. TGFß2 and TGFß3 were significantly (p<0.01, p<0.05) upregulated, almost 3 and 2-fold, respectively in the DE samples compared to healthy subjects. TGFß-RIII was significantly downregulated (p<0.01), almost 2-fold in the DE group..
Conclusions: :
This study reinforces the relevance of TGF-β in ocular surface inflammation and the importance of looking at the three known isoforms and not just to TGF-β1 and -β2. These results may open the possibility of TGFβ-directed therapies for ocular surface inflammation.
Keywords: conjunctiva • cytology • gene/expression