POS0466 RESISTANT STARCH DIET IMPROVES DISTINCT GUT MICROBIOTA STRUCTURES IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS AND ANTIPHOSPHOLIPID SYNDROME

Background

Fiber-poor diets are linked to a reduction in gut microbiota diversity and gut barrier integrity, which is thought to promote the susceptibility to chronic inflammatory disorders1,2. We have previously shown that dietary resistant starch (RS) improves lupus-like disease in a murine model of SLE3 through the modulation of microbiota composition. If similar dysbiotic microbial community structures exist in subsets of SLE patients and if a RS intervention may be efficacious in those patients remains unclear.

Objectives

To test if the dietary RS content in SLE and SLE-related antiphospholipid syndrome (APS) affect gut microbial taxa associated with SLE in published cohorts to date.

Methods

We obtained stool and blood samples as well as diet history for up to 3 visits (0, 4 and 8 weeks) from 12 SLE (n=28) and 15 APS (n=44) patients as well as 20 controls (n=48) as previously published4-6. Microbiota composition was defined by 16S rRNA V4 region sequencing on the Illumina platform and correlated with dietary fiber content extracted from a diet questionnaire. We used the FDA reference list to determine dietary RS contents in patients` regular diets and defined RS quantities as being low if less than 2.5 g/day and as medium if 2.5 to 15 g/day. None of the patients achieved high RS greater than 15 g/day. Mann-Whitney or Kruskal-Wallis tests were performed to compare bacteria relative abundances among the different groups. Simple linear regression was performed to relate the bacterial abundance to RS content and other metadata.

Results

Medium intake of RS was associated with beneficial Bifidobacterium spp. in SLE patients (p=0.016) but not APS (p=0.509). Instead, APS patients who consumed medium quantities of RS in their diets had less gut bacterial taxa that are capable of producing cardiolipins (among them Collinsella; p=0.009) and Ruminococcus gnavus (p=0.0142), a species previously associated with lupus nephritis7. A recent Japanese metagenome-wide study8 associated Streptococcus spp. and related redox reaction genes with SLE, which may also affect oxidative processes in APS9. We therefore also explored Streptococcus levels in SLE and APS patients and found unexpectedly a significant reduction of streptococci in a subset of APS (p=0.004) but not SLE patients (p=0.451) in medium compared to low RS dietary content. Streptococcus abundance was correlated with both Collinsella (R2=0.3141; p=<0,0001) and Ruminococcus gnavus (R2=0.1687; p=<0,0056) in APS patients.

Conclusion

Medium compared to low RS quantities in the regular diets of SLE and APS patients were associated with unique alterations in gut microbial community structures. Bifidobacterium increased in SLE patients with diets containing medium RS whereas APS patients with medium RS carried less cardiolipin-synthesizing taxa and lupus-related pathobionts. In particular, Streptococcus species recently strongly associated with SLE and redox reactions in Japanese patients in a metagenome-wide study8, were significantly suppressed in APS patients on medium RS diets. This modulatory effect was not seen in SLE patients or control subjects consuming medium RS. Together, these findings support distinct dietary effects on autoimmune gut microbiomes depending on the disease state. They also suggest potential beneficial effects of increased RS content on gut microbiota in SLE and APS patients. Fully resolving gut microbial signatures and clinical characteristics in these patients may identify the ideal subset to benefit from an interventional pilot trial with RS.

References

[1] Thorburn et al., 2014, Immunity 19, 833-842

[2] Ruff et al, 2020, Nat Rev Microbiol 18, 521-538

[3] Zegarra-Ruiz et al., 2019, Cell Host Microbe 25, 113-127

[4] Greiling et al., 2018, Science Transl Med 10, 1–15

[5] Manfredo Vieira et al, 2018, Science 359, 1156-1161

[6] Ruff et al., 2019, Cell Host Microbe 26, 1–14

[7] Azzouz et al., 2019, Ann Rheum Dis 78, 947–956

[8] Tomofuji et al., 2021, Ann Rheum Dis 80, 1575–1583

[9] Giannakopoulos and Krilis, 2013, New Engl J Med 368, 1033-1044

Acknowledgements

The work was supported by grants from the National Institutes of Health (NIH) (R01AI118855, T32AI07019), Arthritis National Research Foundation, Arthritis Foundation, Lupus Research Alliance, and Maren Foundation.

Disclosure of Interests

Márcia Pereira: None declared, Iryna Kulyk: None declared, Sylvio Redanz: None declared, William E Ruff: None declared, Teri M. Greiling: None declared, Carina Dehner: None declared, Odelya Pagovich: None declared, Daniel Zegarra Ruiz: None declared, Cassyanne Aguiar: None declared, Doruk Erkan: None declared, Martin Kriegel Speakers bureau: Novartis, BMS, GSK, MSD, Grant/research support from: AbbVie, Employee of: Roche.

Magnesium-Dependent Promotion of H2O2 Production Increases Ecological Competitiveness of Oral Commensal Streptococci

The pyruvate oxidase (SpxB)-dependent production of H₂O₂ is widely distributed among oral commensal streptococci. Several studies confirmed the ability of H₂O₂ to antagonize susceptible oral bacterial species, including caries-associated Streptococcus mutans as well as several periodontal pathobionts. Here we report a potential mechanism to bolster oral commensal streptococcal H₂O₂ production by magnesium (Mg²⁺) supplementation. Magnesium is a cofactor for SpxB catalytic activity, and supplementation increases the production of H₂O₂ in vitro. We demonstrate that Mg²⁺ affects spxB transcription and SpxB abundance in Streptococcus sanguinis and Streptococcus gordonii. The competitiveness of low-passage commensal streptococcal clinical isolates is positively influenced in antagonism assays against S. mutans. In growth conditions normally selective for S. mutans, Mg²⁺ supplementation is able to increase the abundance of S. sanguinis in dual-species biofilms. Using an in vivo biophotonic imaging platform, we further demonstrate that dietary Mg²⁺ supplementation significantly improves S. gordonii oral colonization in mice. In summary, our results support a role for Mg²⁺ supplementation as a potential prebiotic to promote establishment of oral health-associated commensal streptococci.