The role of miR-29b in ADAM 12 & 19 expression in lamina cribrosa cells in glaucoma

Background: Despite glaucoma accounting for a vast proportion of visual loss globally, commercially available therapeutic strategies target only one aspect of its complex multifactorial pathogenesis. Extracellular matrix (ECM) remodelling, deposition and stiffening at the lamina cribrosa (LC) of the optic nerve head (ONH) are all hallmarks of glaucomatous optic neuropathy which remain unaddressed. ECM gene expression at the LC is altered, leading to the fibrotic transformation of these cribriform plates. This process is driven by many factors; notably Transforming Growth Factor-β (TGF-β), a well-known driver of fibrosis. TGF-β has been reported to influence the expression of matrix metalloproteases (MMPs) and disintegrin metalloproteases (ADAMs), major drivers of ECM remodelling. Recent research details the development of microRNA (miRNA) based therapeutics in fibrotic disease. MiR-29 is believed to function as an ‘anti-fibrotic’ miRNA, under expressed in fibrotic disorders and closely linked with TGF-β expression. The objective of this thesis was to examine the effect of miR-29b modulation at the LC in glaucoma. In particular, we focused on the effect of miR-29b on ADAM gene expression in LC cells. Methods: Primary age-matched human normal and glaucoma LC cells were cultured, grown to confluency and a proportion were treated with TGF-β1. A subset of cells were transfected with a miR-29b mimic or mimic control. The baseline gene transcription differential between normal LC cells and glaucoma LC cells was examined. Results: ADAM12 and ADAM19 expression was upregulated in glaucoma LC cells. MiR-29b expression was reduced in glaucoma LC cells compared to normal. TGF-β1 increased ADAM expression and reduced miR-29b expression. Transfection of LC cells with a miR-29b mimic resulted in reduced ADAM12 & 19 expression, despite treatment with TGF-β1. Similarly miR-29b transfection reduced ECM genes, collagen 1a1 and fibronectin expression in NLC and GLC in the presence of TGF-β1. Conclusion: In summary, transfection with a miR-29b mimic controlled TGF-β1 induced overexpression of ADAM12 and ADAM19, playing a pivotal role in the pro-fibrotic transformation of the LC cell in glaucoma. Together, these results demonstrate the potential therapeutic role of miR-29b in the pro-fibrotic transformation evident at the ONH in glaucoma.