EFFECT OF THE ABSENCE OF BOTH, APOLIPOPROTEIN E AND COMPLEMENT FACTOR H, ON RETINAL GENE EXPRESSION, ENZYMATIC ACTIVITY AND LIPID PROFILE.

Abstract

Purpose: The Apolipoprotein E deficient mouse (apoE-/-), an experimental model of genetic hypercholesterolemia, shows retinal protein pattern expression alterations. Complement factor H (cfh) is involved in inflammatory processes associated with retinal degenerations such as Age related Macular Degeneration (AMD). Previous studies carried out in our laboratory with cfh-/-/apoE-/- (DKO) and cfh+/-/apoE-/- (EKHH) animals showed morphological and functional changes in the retina. We aimed to investigate the effect of these genetic modifications in retinal gene expression and enzymatic activity as well as the lipid profile in plasma.

Methods: Twelve-month old wild type (WT), DKO and EKHH mice were divided into 5-6 animals per group (all mice were in C57BL6/J background). Zymography for matrix metalloproteinase-2 (MMP-2) activity and real-time polymerase chain reaction (RT-PCR) for 5 genes expression [CFH, MMP-2, MMP-9, complement factor I (CFI) and Superoxide dismutase (SOD1)] was assessed on retina samples. Mice plasmas were tested with Cobas C-311 analyzer for lipid profile (Total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides) study.

Results: MMP-2 activity was increased in DKO animals whereas it was decreased in EKHH compared with WT controls. These results agree with those obtained in RNA expression RT-PCR where MMP-2 and MMP-9 were over-expressed for DKO mice and down-expressed for EKHH vs. WT. SOD-1 gene expression was downregulated for EKHH animals (P<0.05) while DKO showed no change. As expected, CFH expression was downregulated in both transgenic mice groups (P<0.05). In addition, lipid profile showed an increase in total cholesterol and LDL-cholesterol in both groups of genetically modified animals vs. WT (P<0.05).

Conclusions: The absence of apoE and cfh genes seems to be related to extracellular matrix remodeling and oxidative stress alteration in the retina according to the changes observed in metaloproteinases activity and gene expression and SOD1 gene expression.

Keywords: 637 pathology: experimental • 533 gene/expression • 412 age-related macular degeneration