Background/Purpose: Gut dysbiosis and Th17/Treg imbalance contribute to rheumatoid arthritis (RA). Additionally, methotrexate (MTX) efficacy depends on gut microbiota composition, especially on the presence of B. fragilis and butyrate (Zhou B, et al. Front Microbiol. 2022). Dietary fibres improve gut microbiota composition and increase microbiota-derived short-chain fatty acids including butyrate, that may restore immune tolerance.We aimed to evaluate whether dietary fiber supplementation in patients with RA improves disease activity, Th17/Treg balance and response to MTX.

Methods: Superfibres was a randomized, double-blind, placebo-controlled trial, including  patients with active RA despite stable doses of csDMARDs. Patients were randomized 1:1 to inulin (12 g/day) or placebo for 30 days.  EULAR response and change in peripheral Th17/Treg subsets (flow cytometry) were compared. Subgroup analyses compared MTX vs. non-MTX patients.

Results: A total of 49 patients were included (26 in the fiber group, 23 in the placebo group) with 85.7% women, a mean age of 62 ± 10 years and a mean DAS28 was 3.86 ± 0.61. Odds of EULAR response were markedly higher with fiber (OR 4.65, 95% CI 1.15–18.9; p=0.03). Fiber reduced circulating Th17 cells and the Th17/Treg ratio compared with placebo (p < 0.02). A significant treatment × MTX interaction was observed (p=0.011). In MTX users, mean ΔDAS28 was –1.00 with fiber vs –0.34 with placebo (Fig. 1). No effect was seen in non-MTX patients (n=6). Intervention was well tolerated, with >90% compliance.

Conclusion: This first placebo-controlled RCT of dietary fiber in RA shows that supplementation significantly increases EULAR response rates and improves Th17/Treg balance. This may be explained by an  enhanced MTX efficacy These findings establish the gut–immune axis as a novel therapeutic target and identify dietary fiber as a safe, inexpensive adjunct to MTX in RA. If confirmed, our results have the potential to change clinical practice and improve MTX efficacy in daily practice.

DeltaDAS28 by treatment and background therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/dietary-fiber-supplementation-enhances-methotrexate-response-and-restores-th17-treg-balance-in-rheumatoid-arthritis-results-from-the-superfibre-randomized-trial/