Gut-Joint Axis: Impact of Bifidobacterial Cell Wall Lipoproteins on Arthritis Development

Gut microbiota affects progression of rheumatoid arthritis (RA). The present study aims at investigating the protective potential of Bifidobacterium longum cell wall lipoproteins (Lpps) shown to modulate the intestinal microbiome and prevent osteoarthritis. Arthritis was induced by collagen (CIA) or anti-collagen antibodies (CAIA) injection. Intake of 0.5 mg Lpps /L, but not 0.25 and 1mg Lpps/L significantly alleviated RA symptoms in CIA DBA/1OOaHsd mice. Arthritis index (AI) was also reduced in CAIA mice. In CIA protected group, colon Ligilactobacillus murinus, caecal Lactobacillus johnsonii and spleen weight correlated with AI, whereas the reverse was observed with splenic CD11c+ dendritic cells (cDCs). The unprotected CIA Lpps group harbored higher caecal and colon E. coli and lower caecal L.murinus. Lpps administration to CAIA mice after arthritis induction led to lower colon E. plexicaudatum counts. Splenocytes from CIA protected mice triggered by LPS secreted higher Il-10 than control ones. However, higher IL-10 response was not elicited in gnotobiotic RA mice splenocytes with lower cDCs recruitment. Labeled bacteria with Lpps signal were detected in CIA mice bone marrow (BM) cDCs 5 and 16h post-gavage but not in Peyer’s patches and spleen. In vitro uptake of Lpps by primary BM and thymus cells was observed within 24h. FACS analysis detected the Lpps signal in the plasmacytoid cell compartment but not in cDCs. In conclusion, Lpps dosing is critical for preventing arthritis progression and appropriately modulating the microbiome. Our results also highlight the possible triggering of the immune system by Lpps.