Abstract
Purpose :
Our understanding of the etiology of uveitis and its driving mechanisms remain limited, although anecdotal evidence has linked flares of uveitis to microbial infections in some cases. Alteration in gut microbiota (dysbiosis) has been associated with other autoimmune diseases both in humans and animal models, however such studies in uveitis have been limited to animal models. The purpose of this study is to assess whether there are specific alterations in gut microbiota among uveitis patients.
Methods :
Twenty uveitis patients were enrolled in a clinical study at the NEI (NCT01859299) to evaluate the rectal microbiome. Rectal fluids collected according to a standardized protocol obtained through anoscopy following saline enema administration were analyzed using 16S rRNA sequencing with the F515/R806 primers on a HiSeq 2500 to a depth of greater than 100,000 sequences per sample. Results were compared to rectal fluids of healthy controls collected at UCLA for a HIV microbiome study.
Results :
Rectal fluid samples of thirteen of the twenty patients have been analyzed. Average age was 54 years (48 yrs among controls), majority were posterior segment uveitis and were on systemic treatment. The degree of microbiome diversity among uveitis patients was not significantly different than in controls, though there was a trend towards increased diversity in uveitis patients. However, prominent differences in microbial composition were noted between uveitis and control samples. Among these, we highlight the genus Prevotella, which was undetectable among uveitis patients (0 of 13 samples) whereas it was present in 13 of 20 control samples (p=3x10-5). Median abundance of Prevotella among controls was 29.63% and among uveitis it was 0.54% (p<0.001). Additionally, unclassified Enterobacteriaceae (56 fold; q=1x10-10) and Fusobacterium (31 fold; q=5x10-5) were enriched among uveitis samples.
Conclusions :
While these results are preliminary, there seem to be significant differences between uveitis patient samples and healthy controls, however we cannot rule out potential effects of treatment. The unprecedented association of Prevotella as a health-associated taxon merits further investigation. Studies to further validate the changes in gut microbiome in untreated new onset uveitis patients are underway.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.