An Exploratory Study Provides Insights into MMP9 and A beta Levels in the Vitreous and Blood across Different Ages and in a Subset of AMD Patients

Matrix metalloproteinase-9 (MMP9) and total amyloid-beta (A beta) are prospective biomarkers of ocular ageing and retinopathy. These were quantified by ELISA in the vitreous and blood from controls (n = 55) and in a subset of age-related macular degeneration (AMD) patients (n = 12) for insights and possible additional links between the ocular and systemic compartments. Vitreous MMP9 levels in control and AMD groups were 932.5 +/- 240.9 pg/mL and 813.7 +/- 157.6 pg/mL, whilst serum levels were 2228 +/- 193 pg/mL and 2386.8 +/- 449.4 pg/mL, respectively. Vitreous A beta in control and AMD groups were 1173.5 +/- 117.1 pg/mL and 1275.6 +/- 332.9 pg/mL, whilst plasma A beta were 574.3 +/- 104.8 pg/mL and 542.2 +/- 139.9 pg/mL, respectively. MMP9 and A beta showed variable levels across the lifecourse, indicating no correlation to each other or with age nor AMD status, though the smaller AMD cohort was a limiting factor. A beta and MMP9 levels in the vitreous and blood were unrelated to mean arterial pressure. Smoking, another modifiable risk, showed no association with vitreous A beta. However, smoking may be linked with vitreous (p = 0.004) and serum (p = 0.005) MMP9 levels in control and AMD groups, though this did not reach our elevated (p = 0.001) significance. A bioinformatics analysis revealed promising MMP9 and APP/A beta partners for further scrutiny, many of which are already linked with retinopathy.