SHORT CHAIN FATTY ACIDS MITIGATE OSTEOCLAST‐MEDIATED ARTHRITIC BONE REMODELLING

Abstract

ObjectiveTo study the effects of Short Chain Fatty Acids (SCFAs) on arthritic bone remodeling.MethodsWe treated a recently described preclinical murine model of psoriatic arthritis (PsA), R26STAT3Cstopfl/fl CD4Cre mice, with SCFA supplemented water. We also performed in vitro osteoclast differentiation assays in the presence of serum‐level SCFAs to evaluate the direct impact of these microbial metabolites on maturation and function of osteoclasts. We further characterized the molecular mechanism of SCFAs by transcriptional analysis.ResultsThe osteoporosis condition in R26STAT3Cstopfl/fl CD4Cre animals is attributed primarily to robust osteoclast differentiation driven by an expansion of osteoclast progenitor cells (OCPs), accompanied by an impaired osteoblast development. We show that SCFA supplementation can rescue the osteoporosis phenotype in this model of PsA. Our in vitro experiments revealed an inhibitory effect of the SCFAs on osteoclast differentiation, even at very low serum concentrations. This suppression of osteoclast differentiation enabled SCFAs to impede osteoporosis development in R26STAT3Cstopfl/fl CD4Cre mice. Further interrogation revealed that bone marrow derived OCPs from diseased mice expressed a higher level of SCFA receptors than that of control mice and that the progenitor cells in the bone marrow of SCFA‐treated mice presented a modified transcriptomic landscape, suggesting a direct impact of SCFAs on bone marrow progenitors in the context of osteoporosis.ConclusionWe demonstrated how gut microbiota‐derived SCFAs can regulate distal pathology, i.e., osteoporosis, and identified a potential therapeutic option for restoring bone density in rheumatic disease, further highlighting the critical role of the gut‐bone axis in these disorders.image