Clinical Significance of Gut Microbiota Community Types for Long-term Response to Fecal Microbiota Transplantation in Patients with Psoriatic Arthritis.

Fecal microbiota transplantation (FMT) holds promises as a beneficial supplement to methotrexate in patients with psoriatic arthritis (PsA). We therefore investigated how gut bacterial signatures in patients and donor strain engraftment associated with long-term response to FMT. This exploratory study is based on the FLORA trial cohort encompassing 31 patients with moderate-to-high PsA disease activity and four FMT donors. Out of fifteen patients receiving one single-donor FMT, thirteen were included in the per-protocol (PP) population. Stool samples were collected before and after FMT (week 4, 12, and 26). We performed shotgun metagenomics to characterize gut microbiota features. At baseline, 17 patients (55%) had a gut microbiota community type dominated by the Bacteroides genus (B-type) while 14 (45%) had a Prevotella-driven community type (P-type). The B- and P-type patients did not differ in disease activity nor demographics, but the B-type had a significantly higher species diversity compared to the P-type (P=0.005). In the PP population, five out of seven B-type patients vs none out of six P-type patients (P=0.021) achieved a long-term clinical beneficial response at week 26. Bacterial strain richness increased significantly from baseline to week 4 and 26 in B-type (P=0.016), but not in P-type, patients. Eighteen engrafted strains persisted only in B-type recipients by week 26, including a Bacteroides clarus strain, which demonstrated a negative effect size regarding arthritis pain and the patients' global assessment of disease. Recipients with a Bacteroides-dominated community structure were more likely to achieve long-term beneficial response following one FMT.