Transcriptional regulation of immunometabolism modulates macrophage (M0) behaviour and protects against the onset and expansion of atrophy in a rodent model of age related macular degeneration (AMD) with geographic atrophy (GA)

Abstract

Purpose : Abnormalities in lipid handling and innate immunity are implicated in AMD and we hypothesize that M0 polarization toward a pro-inflammatory (M1-like) phenotype reflects orchestrated changes in immunometabolic gene expression that can be pharmacologically targeted by modulating fatty acid binding protein (FABP) and lipid-activated nuclear receptor transcription factor (NR/TF) activity. The purpose of this study was to determine the protective activity of fatty acid mimetic (FAM) compounds, a newly defined class of molecules, to alter NFkB and PPAR signaling, and complement C3 under conditions of stress.

Methods : Oxidative and nitrosyl stress were induced in adult rats by intravenous (iv) sodium iodate (45mg/kg), with or without iv nitroglycerine (NTG, 11mg/kg/min*30min), and in human hTERT-RPE1 cells in vitro. Area of atrophy & potential exudation were evaluated by in vivo imaging, and retinal function by ERG. mRNA expression was quantified by qPCR and gene arrays, with supporting immunohistochemistry. Binding within lipid-bearing domains of human proteins was assessed by in silico modeling. Treatment with intravitreal (IVT) TMi-018 (0.2-100ug/eye), an indazole derivative, and BMS309403 (30ug/eye), a known FABP4 inhibitor, were compared against IVT saline. Transcriptional read-outs of NFkB and PPARg activity were assessed, along with complement C3 and its receptor. ANOVA was used for multiple comparisons, and REST analysis for PCR fold change (GraphPad Prism).

Results : IVT TMi-018 dose-dependently protected against the onset and expansion of atrophy (n=76; by up to 100%), preserved retinal function, reduced M0 recruitment, and reduced pro-inflammatory NFkB mediated mRNA expression, including monocyte chemoattractant protein-1 (MCP-1), IL-6, and TNFa, (p<0.05 in all). BMS309403 was protective to a lesser extent but was toxic by IVT delivery. PPARg mRNA targets UCP-1, CD36 and LXR were not altered (p>0.05). C3 and C3RA1 were reduced, with no exudation (p<0.05). hTERT-RPE viability to NaIO3 and NaIO3+NTG was preserved (p<0.05).

Conclusions : Transcriptional regulation of aggressive macrophages is a novel therapeutic approach for GA. FAM molecules targeting lipid chaperones & NR/TFs can modulate master regulators of inflammation and metabolism to provide tissue protection

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.