Rheumatoid arthritis (RA) is a chronic autoimmune disease. Its pathological features are synovial inflammation, bone erosion, and joint structural damages. Our previous studies have shown that kefir peptides (KPs) can reduce cardiovascular disease, osteoporosis and renal inflammation. In this study, we further evaluate the efficacy of KPs on adjuvant-induced arthritis (AIA) in a rat model.
After the 14th day of adjuvant induction, rats were subsequently orally administered KPs (83 or 166 mg/day/kg) or tofacitinib (6.2 mg/day/kg) for 14 days. On the 28th day, the rats were anesthetized with isoflurane for ultrasonic, in vivo imaging system (IVIS), and radiographic imaging and then sacrificed for ankle tissues collection and analysis. In vitro, IL-1β-treated human synovial cells (SW982) were subjected to anti-arthritis mechanism study in the presence of KPs.
The results of ultrasonography, radiograph, histology, the expression of matrix metalloproteinases (MMPs), inflammatory cytokines and RANKL/OPG ratio demonstrated decreasing severity of synovitis and bone erosion in the ankle joints after KPs treatment. Activation of the NF-κB and MAPK pathways was significantly reduced in KPs treated AIA group. Furthermore, KPs attenuated IL-1β-induced inflammatory cytokine production and the expression of MMPs in a human synovial cell line SW982. These results demonstrated that KPs alleviated adjuvant-induced arthritis in rats by inhibiting IL-1β-related inflammation and MMPs production.
We concluded that KPs can exhibit anti-inflammatory effects by reducing the levels of macrophage-related inflammatory cytokines and MMPs, thus alleviating bone erosion in the ankle joint and constituting a potential therapeutic strategy for rheumatoid arthritis.

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