Abstract
Purpose :
Dysbiosis in the gut bacterial microbiome is associated with Diabetes Mellitus (DM) patients. But, as yet, we do not have any indication whether dysbiosis in the gut bacterial microbiome is also a feature of Diabetic Retinopathy (DR) patients? The aim of the study is to establish the gut bacterial microbiomes of healthy controls (HC) and DM and DR patients and to assess whether dysbiosis is associated with DR patients.
Methods :
Fecal samples from 30 HC, 25 DM and 31 DR subjects served as the source of DNA from which V3-V4 region of the bacterial 16S rRNA gene was amplified. The V3-V4 amplicon libraries were prepared according to Illumina protocol and sequenced using an Illumina HiSeq platform. The high quality assembled reads were used for operational taxonomic unit (OTU) picking using QIIME pipeline. Alpha diversity indices (Shannon diversity, Simpson index, number of observed OTUs and Chao1 index) of the microbiomes were plotted and a t-test performed to identify significant differences between the 3 groups. Kruskal Wallis was also performed to identify the taxonomic groups (at the OTU, phylum and genus level) which were differentially abundant between HC, DM and DR samples. Non-metric multidimensional scaling (NMDS) plots of microbiome libraries were generated (using Bray-Curtis dissimilarity) based on OTUs. Interaction networks were also generated in the 3 cohorts of microbiomes using CoNet.
Results :
1. Analysis of the gut bacterial microbiomes confirm earlier observations that in DM group the abundance of several OTUs, two phyla (Elusimicrobia and Crenarchaeota) and several genera were decreased.
2. This is the first study demonstrating that at the OTU, phyla and genera level DR gut microbiomes were more discriminatory than DM microbiomes with respect to HC.
3. Gut bacterial microbiomes of DM and DR did not show significant differences at the OTU, phyla and genera level.
4. Inferred functional analysis of the bacterial diversity indicated a dominance of probiotic and anti-inflammatory bacteria in HC and followed the sequence HC>DM>DR. DR had a predominance of pathogenic bacteria.
Conclusions :
First report of dysbiosis in the gut bacterial microbiome in Diabetic Retinopathy patients.Such studies would lead to identification of bacteria that are associated with DR microbiomes and help in developing therapies to improve treatment of DR.
This is a 2020 ARVO Annual Meeting abstract.