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John Kenneth George Dart, Sarah Dale, Julie T Daniels, Valerie P J Saw, David Abraham; Aldehyde dehydrogenase (ALDH) inhibition is a novel potential therapy for conjunctival fibrosis in ocular mucous membrane pemphigoid (OcMMP). Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3038.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously shown that OcMMP human conjunctival fibroblasts (HCF) maintain their phenotype in culture. We hypothesize that in vitro models of OcMMP HCF activity may predict conjunctival scarring mechanisms in-vivo and allow us to identify profibrotic targets, and analyse their therapeutic potential. We have used gene expression, proteomics and western blots of whole OcMMP conjunctival tissue, and OcMMP HCF, to identify putative conjunctival scarring inhibitors. We investigated the therapeutic potential of these inhibitors in our in vitro HCF model.
Gene expression on whole OcMMP conjunctiva and on cultured OcMMP HCF was carried out by microarray to identify over expressing genes in OcMMP. Western blots were used to confirm over expression of targets in OcMMP fibroblasts. Kinexus whole tissue proteomics, enabled identification of downstream signaling molecules associated with the target protein. A range of in vitro HCF assays including collagen secretion and production, matrix contraction, proliferation, chemotaxis, and myofibroblast differentiation were used to analyse the role of target proteins.
Gene expression studies identified 14 overexpressed genes in OcMMP. ALDH1A3 was chosen for further study, as being potentially relevant to fibrosis pathways. Protein phosphorylation profiling, in whole OcMMP conjunctiva, identified NF-κBp50, p53 and Bcl-XL as potential ALDH1A3 signaling pathways. Western blot of MMP fibroblasts showed increased ALDH1A3. OcMMP HCF showed increased collagen production, decreased matrix contraction, reduced rates of proliferation, and myofibroblast differentiation. Addition of both DEAB (diethylaminobenzaldehyde) and disulfiram, two selective ALDH inhibitors, restored the functionality of OcMMP HCF to that of Control HCF. Conversely, adding retinoic acid (a downstream product in the ALDH pathway) to Control HCF promoted OcMMP like HCF dysfunction.
These findings taken together show that ALDH1A3 is a novel target involved in the scarring process in OcMMP. In addition they demonstrate that ALDH inhibition may provide a therapeutic approach to fibrosis with application in OcMMP that should be evaluated in other scarring disorders. Disulfiram is licenced for human use, and can be repurposed for this indication.
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