Role of extracellular matrix remodelling gene SNPs in keratoconus.

Introduction: Single nucleotide polymorphisms (SNPs) in genes for certain structural components may be implicated in the pathogenesis of keratoconus. We hypothesized links between SNPs in genes coding for collagen, matrix metalloproteinase 9 (MMP9) and tissue inhibitor of matrix metalloproteinase (TIMP) and keratoconus. Furthermore, we hypothesized links between MMP-9 and TIMP-1 SNPs and their tear level in keratoconus patients.Materials and methods: We genotyped 200 keratoconus and 100 control subjects by allele-specific PCR, and quantified MMP-9 and TIMP1 in tear samples by ELISA.Results: COL4A3 (rs55703767) and MMP-9 (rs17576) G alleles were over-represented in keratoconus patients (P < 0.01). TIMP-1 (rs6609533) A allele was more prevalent in keratoconus females (P < 0.01) but not in males (P = 0.73). MMP-9 was higher (P < 0.001) and TIMP1 lower (P < 0.001) in tear samples from keratoconus patients compared to controls. Keratoconus cases carrying MMP-9 (rs17576) homozygous (GG) alleles had higher tear MMP-9 compared to those carrying the (A) allele (P < 0.01). Females carrying TIMP-1 (rs6609533) homozygous (AA) alleles in both groups had significantly lower tear TIMP-1 compared to carriers of the AG and GG genotypes.Conclusions: This study supports the hypothesis of a functional role for COL4A3 (rs55703767, G/T), MMP-9 (rs17576, A/G) and TIMP-1 (rs6609533, A/G) SNPs in the pathogenesis of keratoconus.

miR-15a: a potential diagnostic biomarker and a candidate for non-operative therapeutic modality for age-related cataract.

Introduction: In order to better understand the role of hsa-miR-15a in the pathogenesis of age-related cataracts, we hypothesised altered expression, and of target anti-apoptotic genes, BCL-2 and MCL-1, in lens epithelial cells amongst age-related cataract patients.Material and methods: Reverse transcription quantitative polymerase chain reaction (RT-qPCR) quantified the expression of hsa-miR-15a and the target genes BCL-2 and MCL-1 in lens epithelial cells of 120 age-related cataract patients (40 patients with cortical cataracts, 40 patients with nuclear cataracts and 40 patients with posterior subcapsular cataracts) and 40 controls. Sixty specimens (15 normal and 45 cataracts) were stained immunohistochemically with BCL-2 and MCL-1 markers.Results: The expression of hsa-miR-15a was significantly increased (p = 0.003) in lens epithelial cells of cataract patients compared to the control group. BCL-2 and MCL-1 expression levels were significantly decreased in cataract patients (p < 0.001). A significant increase in hsa-miR-15a expression in the cortical subtype compared to the posterior subcapsular subtype (p = 0.003) and a significant decrease in BCL-2 and MCL-1 expressions in the cortical subtype compared to the nuclear and the posterior subcapsular subtype was detected.Conclusions: The increased expression of hsa-miR-15a in lens epithelial cells of cataract patients may repress the expression of BCL-2 and MCL-1. The expression of hsa-miR-15a and the subsequent apoptosis of lens epithelial cells are part of the pathogenesis of age-related cataracts.