Investigation of the relationship between genetic polymorphisms of connective tissue growth factor (CTGF) and its tear and aqueous humor levels in pseudoexfoliation syndrome and glaucoma

Pseudoexfoliation syndrome (PES) is an extracellular matrix disease characterized by the production and accumulation of abnormal fibrillary materials in ocular tissues. As a result of the accumulation of pseudoexfoliative material, channels for the drainage of aqueous humor fluid is blocked. This causes intraocular pressure to increase, damages the optic nerve and causes glaucoma (PEG) to appear. PEG can cause complete loss of vision, and this condition has no treatment. The over production of elastic micro fibrils is thought to be an important part of the pathophysiology of PES. For this reason, it is thought that growth factors may have an important role in pathophysiology. It has been shown that TGF-β1 is expressed at higher levels in PES than controls and since CTGF expression is induced by TGFβ, it was thought that CTGF may play a role in PES pathophysiology. Therefore, it was aimed to examine the CTGF polymorphisms rs6918698G/C, rs9399005C/T, rs9402373C/G, rs12526196T/C, which are thought to be affecting expression levels of CTGF. Moreover to measure the CTGF concentrations in tear and aqueous humor to investigate the relations with polymorphisms, and to be able to differentiate PEG and PES was another purpose. Blood samples from 213 PEG, 214 PEG and 215 controls, also tear and aqueous humor samples of some of these people were collected by University of Health Sciences, Gülhane Training and Research Hospital, Ophthalmology Unit, Ankara, Turkey. PCR-RFLP method was used for genotyping of rs6918698G/C and rs9399005C/T while real-time PCR method was used for rs9402373C/G and rs12526196T/C. Total protein concentrations were determined by Bradford assay and CTGF concentrations by ELISA method in tear and aqueous humor samples. According to the logistic regression analysis, being male was 1.8 times related to PEG. The genotypes of the studied polymorphisms did not have a significant association with PEG or PES alone. However, genotyping studies for each of the four polymorphisms were made for the first time in Turkish population and the allele frequencies were determined. As a result of analysis of the combinations of double and triple SNP genotypes according to the frequencies seen in PEG, PES and control groups, it has been seen that some genotype combinations may have risky or protective effect for PES or PEG. Total protein concentrations in the tear and aqueous solution were significantly higher in the PEG group than in the PES and controls. The tear CTGF concentration in PEG and PES patients was found to be significantly higher than the controls. There was no correlation between genetic polymorphisms and tear or aqueous humor CTGF concentrations, total protein concentrations, and CTGF ratio in total protein. There was also no correlation between tear and aqueous humor for these parameters. In this study, many parameters investigated in relation to PES and PEG, such as rs6918698G/C, rs9399005C/T, rs9402373C/G and CTGF concentration in tear, have been dealt with for the first time and the outputs can guide the future studies. In this study, there were relationships investigated for the first time in the world or Turkey, and the data obtained has a value in bioinformatics. At the same time, biomarkers that could be used for PES and PEG diagnosis can be found and devices can be developed for use in diagnostic laboratories directed to these biomarkers. This project contributes to biomedical engineering with these aspects.