Effects of Long Duration of High-Fat Diet on Gut Microbiota Composition and Laser-Induced Choroidal Neovascularization

Abstract

Purpose : Emerging evidence indicates that high-fat diet (HFD)-induced gut dysbiosis exacerbates choroidal neovascularization (CNV), the hallmark lesion of neovascular AMD (nAMD). Previous studies describe the pathogenic effects of short-term (ST) HFD-induced gut dysbiosis on the evolution of nAMD however the impact of long-term (LT) HFD consumption remains unknown. We aim to evaluate and compare the consequences of ST and LT HFD on gut microbiome composition as well as CNV features.

Methods : Seven weeks old male C57BL/6J were fed 23% HFD for 8 weeks (ST-HFD) and 21 weeks (LT-HFD) while control groups were maintained on a regular diet (young-ND and aged-ND, respectively) and then underwent laser induction of CNV. Choroidal flatmounts were immunostained with IB4 isolectin for CNV and IBA-1 for microglia infiltration. 16S rRNA sequencing of fecal DNA from these groups was done on the Illumina MiSeq platform and analyzed by QIIME2.

Results : LT-HFD induced a more prominent effect on gut dysbiosis, reflected by severely suppressed microbial diversity in contrast to the ST-HFD group. Specifically, protective microbes from the phylum (p.) Bacteroidetes/order (o.) Bacteroidales and p.Actinobacteria (o.Bifidobacteriaceae) were further decreased by LT-HFD, while, pathogenic p.Firmicutes (o.Clostridiales) were more prominently increased in the LT-HFD group compared to ST-HFD. The Bacteroidetes to Firmicutes ratio was most affected in the ST-HFD group but somewhat begins to recover in the LT-HFD, as shown in the previous aging-related gut-microbial studies.

LT-HFD caused a larger increase in CNV size compared with the aged ST-ND fed mice (1.62 fold-change, p=0.0049), while the ST-HFD intake compared to ND resulted in a smaller influence on CNV size (1.42fold-increase, p=0.0048). LT-HFD was associated with significantly increased IBA1 activated microglial infiltration within and outside CNV lesion (p=0.003 and p=0.013, respectively), but this was not noted with ST-HFD.

Conclusions : LT-HFD had a more robust effect on gut dysbiosis as well as CNV size and microglial infiltration. Our data indicate that the duration of unhealthy diet intake may influence gut microbial shifts that correlate with nAMD pathogenesis.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.