High-Fat Diet Alters the Retinal Transcriptome Independently of Gut Microbiome in Germ-Free Mice

Abstract

Purpose : High-fat diets (HFD) affect the pathophysiology of retinal diseases including, age-related macular degeneration (AMD), diabetic retinopathy and glaucoma by altering the gut microbiome which can directly affect the retinal transcriptome as already shown by our team. However, the effects of diet independent of gut microbiome on the retinal transcriptome are currently unknown. The purpose of this study is to investigate if HFD can have direct effects on retinal gene expression and pathways independently of the gut-microbiome by comparing the retinal transcriptome of germ-free (GF) mice on a normal diet (ND) to GF mice on HFD.

Methods : RNA was extracted from whole retinas (4 per group) from 15-weeks old GF C57BL/6J male mice fed ND and HFD (23% saturated fat for 8 weeks). RNA-seq was performed on NovaSEQ6000 using the paired-end method. Differentially expressed genes (DEGs) were identified (cutoff p-value <0.01) and functional enrichment network analyses (cutoff FDR B&H <0.05) were created for the DEGs using Toppgene.

Results : After correction of the raw data, 20,287 genes were selected for differential gene analysis. In GF-HFD group, a cohort of 1195 DEGs were identified, 801 were upregulated and 394 were downregulated. Key genes involved in oxidative phosphorylation, the citric acid cycle and electron transport chain were affected. Cellular organelle functions affected by HFD included the spliceosomal complex, mitochondrion, endoplasmic reticulum (ER). Enrichment analysis showed that pathways associated with neurodegenerative disorders including Parkinson’s disease, Alzheimer's disease, and Huntington’s disease were affected by HFD. Notable DEGs include vascular endothelial growth factor receptor 3 (FLT4) and receptor accessory protein 1 (REEP), which play key roles in AMD and retinal degeneration, respectively.

Conclusions : This study demonstrates novel data that diet can directly modulate the retinal transcriptome independently of the gut microbiome. Unbiased analysis of the retinal transcriptome identified genes and pathways involved in retinal metabolism and retinal degenerative disorders affected by HFD alone. Future studies are needed to elucidate the complex relationship between retinal disease, diet and the gut microbiome.

This is a 2021 ARVO Annual Meeting abstract.