Background/Objectives: Osteoporosis (OP) is a frequent complication of rheumatoid arthritis (RA), driven by chronic inflammation and subsequent bone destruction. While deer bone is recognized for its potential bone-health benefits, the therapeutic efficacy of its fermented products on RA-induced OP remains unclear. Methods: This study investigated the protective effects of Lactobacillus reuteri-fermented deer bone water extract (LR-DBW) against OP in an adjuvant arthritis (AA) rat model. Firstly, LC-MS/MS was employed to analyze the differential peptide profiles between LR-DBW and non-fermented deer bone water extract (DBW). Secondly, experiments such as Micro-CT, histological staining, and Western Blot were conducted to detect the improvement effect of LR-DBW on OP. Results:In vivo, LR-DBW administration significantly alleviated arthritis symptoms, increased bone mineral density (BMD), and improved bone microarchitecture in AA rats. In vitro, LR-DBW inhibited RANKL-induced osteoclastogenesis and actin ring formation in RAW264.7 cells. Mechanistically, LR-DBW inhibits the phosphorylation of ERK, JNK and p38 proteins. Conclusions: These research results indicate that one of the mechanisms by which inhibiting osteoclast differentiation into LR-DBW can alleviate osteoporosis caused by rheumatoid arthritis is through down-regulating the phosphorylation expression of ERK, JNK and p38 proteins. This highlights its potential as a functional food component for treating inflammatory bone diseases.
Jiang et al. (Sat,) studied this question.