Objectives: There is increasing evidence of a close link between microbiota and inflammatory diseases. Microbiota has never been studied in large vessel vasculitis (LVV). We aimed to analyse the blood microbiome profile of patients with LVV [Takayasu arteritis (TAK) or giant cell arteritis (GCA)] and healthy donors (HD).
Methods : We studied blood samples of 13 patients with TAK (20 samples), 9 (11 samples) with GCA and 15 HD. The blood microbiome profile was assessed by sequencing of the 16S rDNA blood bacterial DNA. Linear Discriminant Analysis (LDA) coupled with effect size measurement (LEfSe) was used to analyse the differences in the blood microbiome profile between the groups.
Results: Samples of TAK patients showed an increase in the levels of Clostridia, Cytophagia and Deltaproteobacteria and a decrease in Bacilli at the class level as compared to HD (LDA>2, p<0.05). Active compared to inactive TAK patients had significantly lower levels of Staphylococcus. Samples of GCA patients showed an increased abundance of Rhodococcus and an unidentified member of the Cytophagaceae family. Microbiota of TAK compared to GCA patients showed higher levels of Candidatus Aquiluna and Cloacibacterium (LDA>2; p<0.05). Differences in blood microbiome were also associated with a shift of bacterial predicted metabolic functions in TAK compared to HD. Similar results were also found in active compared to inactive TAK patients.
In conclusion , TAK patients showed a specific blood microbiome profile as compared to healthy controls and GCA patients. Among TAK patients, significant changes of blood microbiome profile were associated with specific metabolic functions.