Abstract
Purpose :
No systemic biomarkers for glaucoma can predict progression rates, disease severity, or treatment efficacy. This study aimed to identify systemic (plasma) and local (aqueous humor) biomarkers associated with the G661R missense mutation in the ADAMTS10 gene resulting in open-angle glaucoma (ADAMTS10-OAG) in dogs.
Methods :
Plasma and aqueous humor samples were collected from 24 dogs (14 females & 10 males; median age: 3.5 years, range: 0.9-5.4 years): 19 dogs homozygous for the G661R missense mutation in the ADAMTS10 gene at different stages of OAG, and 5 unaffected controls (i.e., wild-type controls and heterozygous carriers of the G661R missense mutation). Samples were processed for targeted metabolomics via UHPLC-QTOF-MS, identifying >230 annotated metabolites. Data were analyzed using MetaboAnalyst 5.0 in R, normalized by Pareto scaling, and statistical enrichment performed (Fisher’s at an FDR of <0.05) to determine differences between groups. Pathway analysis (KEGG) was performed using differentially changed metabolites from the first analysis.
Results :
Both aqueous humor and plasma demonstrated distinct metabolic profiles between OAG and control groups. Of the 233 metabolites identified, 32 were differentially expressed in the aqueous humor of ADAMTS10-mutant dogs. In comparison, 21 metabolites were differentially expressed in plasma samples. The following 7 metabolites were differentially expressed in plasma and aqueous humor: N-acetyltryptophan, kynurenic acid, 2-ketobutyric acid, 4-trimethylammoniobutanoic acid, cis-4-decenoylcarnitine, 3-methylhistidine, and gamma-aminobutyric acid. While only one pathway was significantly affected in the mutant plasma – valine, leucine, and isoleucine biosynthesis – the following 7 pathways were altered in the mutant aqueous humor: alanine, aspartate & glutamate, butanoate, citrate cycle, propanoate, glyoxylate and dicarboxylate, and D-glutamine and D-glutamate metabolisms, as well as lysine degradation.
Conclusions :
In this initial metabolomic study, changes in metabolites were found in plasma and aqueous humor in a clinically relevant and well-established large animal OAG model. Metabolomics may be a valuable tool to stage diseases and assess response to therapy.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.