Bu­Shen­Ning­Xin decoction suppresses osteoclastogenesis by modulating RANKL/OPG imbalance in the CD4+ T lymphocytes of ovariectomized mice.

ABSTRACT

Postmenopausal osteoporosis (PMO) has been recognized as an inflammatory condition. CD4+ T cells serve a key role in the interaction between bone metabolism and the immune system. Bu­Shen­Ning­Xin decoction (BSNXD), a traditional Chinese medicine, has been ultilized as a remedy for PMO. In the present study, the aim was to investigate the immune modulatory effects of BSNXD on CD4+ T cells, receptor activation of nuclear factor κB ligand (RANKL)/osteoprotegerin (OPG) imbalance, skeletal parameters and osteoclastogenesis. Ovariectomized (OVX) mice were treated with a series of concentrations of BSNXD and then autopsied. The bone phenotype was analyzed by micro computed tomography. CD4+ T cells were isolated and their percentage was measured using flow cytometry (FCM). RANKL and OPG expression by the CD4+ T cells at the transcriptional and translational levels were quantified by reverse transcription-quantitative polymerase chain reaction, ELISA and FCM. CD4+ T cells were cultured with blood serum derived from BSNXD­treated OVX mice (BSNXD­derived serum) and the apoptosis rate was quantified by FCM. CD4+ T cells were co-cultured with bone marrow­derived macrophages and exposed to BSNXD­derived serum to whether CD4+ T cells are involved in BSNXD­modulated osteoclastogenesis and the results were quantified via tartrate­resistant acid phosphatase staining. The results revealed that BSNXD ameliorated OVX­induced bone loss, prevented the expansion of CD4+ T cells and restored the RANKL/OPG imbalance in the CD4+ T cells of OVX mice. In vitro, BSNXD­derived serum promoted the apoptosis of CD4+ T cells. The co­culture system demonstrated that CD4+  T cells from OVX mice increase osteoclastogenesis, while this effect was suppressed by BSNXD administration. The findings of the study collectively suggest that BSNXD exerts an immunoprotective effect on the bone phenotype of OVX mice by ameliorating RANKL/OPG imbalance in CD4+ T cells and attenuating osteoclastogenesis.