OP0047 FASTING MODULATES THE HUMAN GUT MICROBIOME AND REDUCES AN IL-17+/IFNG+ T CELL-INDUCING GUT PATHOBIONT IN PATIENTS WITH RHEUMATOID ARTHRITIS
Authors: M.S. Pereira, K. Stuhlträger, N. Effelsberg, A. Rajput Khokhar, S. Redanz, H. Ebid, B. Hansen, C.C. Laczny, U. Löschberger, S. Bletz, J.G. Schneider, P. Wilmes, C.S. Kessler, A. Michalsen, A. Mellmann, M.A. Kriegel
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> The mucosal origins hypothesis suggests rheumatoid arthritis (RA) is triggered at mucosal sites in genetically predisposed hosts[1]. Murine models of inflammatory arthritis support that intestinal microbiota-induced T helper 17 (Th17) cells are involved in the pathogenesis of RA[2] and other rheumatic diseases[3,4]. Dietary interventions are known to modulate human gut microbial community structures and host immunity. Specifically, a ketogenic diet in patients with metabolic disease was shown to decrease gut Th17 cells in mice by reducing bifidobacteria via ketone bodies[5]. However, which host-microbiota interactions are involved in fasting of patients with RA, that improves disease activity clinically[6], are currently unknown. <h3>Objectives:</h3> We set out to characterize the gut microbial communities, key metabolites, and host-microbiota interactions with a focus on type 17 immunity in a cohort of patients with RA who underwent fasting. <h3>Methods:</h3> Stool and serum samples were obtained from a subset of patients with RA enrolled in the NutriFast study[6]. 10 patients fasting (~300 Kcal) for 7 days and 8 patients under an anti-inflammatory diet were analyzed with regards to microbiomes, metabolomes, and clinical parameters. Fecal microbiota composition was defined by full-length 16S rDNA sequencing on the PacBio platform. Diet-sensitive taxa were profiled longitudinally by quantitative PCR. A cytokine-bead array assay was used to measure cytokine levels in the serum. Beta-hydroxybutyrate (BHB) was determined via dried blood spot metabolomics. Candidate taxa were isolated from the stool of patients with RA by culture (Bifidus Selective Medium Agar) and co-cultured with PBMCs from healthy individuals to determine human Th17 induction <i>in vitro</i> in the presence of CD3/CD28 beads or IL-2. Uncorrected Fisher´s LSD was used to compare baseline and intervention among both groups and Mann Whitney U test to compare BHB or bacterial abundances between groups. <h3>Results:</h3> One week of fasting significantly reduced the HAQ score (p = 0.019) and circulating lymphocyte counts (p = 0.011) of patients with RA, while increasing ketone bodies (BHB; p &lt; 0.0001) compared to an anti-inflammatory diet. The gut microbiota composition was also different between groups. In particular, <i>Bifidobacterium adolescentis</i> (BA) was the most strongly reduced species after seven days of fasting compared to the control group, which was confirmed by a species-specific qPCR analysis (p = 0.030). The absence of BA after fasting was modestly associated with higher circulating levels of BHB (p = 0.095). Independently of the dietary regimens, BA+ patients with RA displayed higher serum levels of IL-17 compared to patients not colonized with this species (p = 0.0219). <i>In vitro</i> studies on human PBMCs revealed that a BA isolate from an RA patient prior to fasting and the type strain of BA both induce IL-17/IFNg cytokine co-production in human CD3+ T cells as typical for pathogenic Th17 cells. <h3>Conclusion:</h3> A fasting intervention for seven days in patients with RA altered the gut microbiota compared to an anti-inflammatory diet. Fasting decreased BA, a species which was able to induce human IL-17-producing T lymphocytes <i>in vitro</i>. BA was previously shown to induce intestinal Th17 in mice[5], exacerbate experimental arthritis[7], and disrupt epithelial barrier function[8]. Altogether, our results put forth a diet-sensitive candidate pathobiont in human RA that warrants further study. They also delineate a host-microbiota interaction that may partly explain the rapid, beneficial effects of fasting in patients with RA. <h3>REFERENCES:</h3> [1] Holers et al., 2018 Nat Rev Rheumatol 14(9), 542-557. [2] Evans-Marin et al., 2018 Arthritis Rheumatol 70(12), 1971-1983. [3] Manfredo Vieira et al., 2018 Science 359(6380), 1156-1161. [4] Gronke et al., 2023 bioRxiv. [5] Ang et al., 2020 Cell, 181(6), 1263-1275 e1216. [6] Hartmann et al, 2022 Front Nutr, 9, 1030380. [7] Tan et al, 2016 Proc Natl Acad Sci U S A, 113(50), E8141-E8150. [8] Bootz-Maoz et al., 2022, Cell Reports 41, 111657. <h3>Acknowledgements:</h3> Mengwei Niu for stool sample preparations. <h3>Disclosure of Interests:</h3> Márcia S. Pereira: None declared, Katja Stuhlträger: None declared, Natalie Effelsberg: None declared, Anika Rajput Khokhar: None declared, Sylvio Redanz: None declared, Hebah Ebid: None declared, Bérénice Hansen: None declared, Cédric C. Laczny: None declared, Ulrike Löschberger: None declared, Stefan Bletz: None declared, Jochen G. Schneider: None declared, Paul Wilmes: None declared, Christan S. Kessler: None declared, Andreas Michalsen: None declared, Alexander Mellmann: None declared, Martin A. Kriegel Novartis, GSK, Roche, Genentech, MSD, AstraZeneca, Roche, Roche, BMS, Eligo Biosciences, Enterome, Maat Pharma, Roche, AbbVie, BiomX.