β-Sitosterol modulates macrophage polarization and attenuates rheumatoid inflammation in mice

AbstractContext: β-Sitosterol (BS), the primary constituent of plants and vegetables, exhibits multiple biological effects.Objective: This study explores its effect of immune-regulation on macrophages and its potential for rheumatoid arthritis (RA) therapy.Materials and methods: In vitro, bone marrow-derived macrophages (BMDMs) were treated with 5, 25 and 50 μM BS in the M1 or M2 polarization conditions. In vivo, either i.p. injection with 20 or 50 mg/kg BS every 2 d after boost immunization of collagen-induced arthritis (CIA) or adoptive transfer of 2 × 106 BS-treated BMDMs (BS-BMDMs) at the day before CIA were adopted in mice to test the therapeutic effect. IL-10 antibody depletion was used in the period of above treatments to discuss the underlying mechanism.Results: The phenotypes and function of BMDMs showed that 5, 25 and 50 μM BS significantly repressed the M1 polarization and augmented M2 polarization dependent upon concentration. The expression of iNOS, IL-1β, CD86 and MHCII in 25 μM BS-treated M...