[Tenghuang Jiangu Capsules promote Treg cell differentiation in rat model of postmenopausal osteoporosis via modulation of SIRT1-mediated JAK3/STAT5 pathway].

This study aims to explore the effect and molecular mechanism of Tenghuang Jiangu Capsules(TJC) on postmenopausal osteoporosis(PMOP) by regulating Treg cell differentiation. A rat model of PMOP was established by removing bilateral ovaries for eight weeks. The successfully modelled rats were randomized into model, positive control(estradiol valerate, 0.09 mg·kg~(-1)), high-dose(0.36 g·kg~(-1)) TJC, medium-dose(0.18 g·kg~(-1)) TJC, low-dose(0.09 g·kg~(-1)) TJC, and SIRT1 inhibitor(EX-527, 1 mg·kg~(-1)) groups(10 per group). Eight weeks after the modeling, equal volumes of normal saline, estradiol valerate, and TJC were administrated by gavage, and the SIRT1 inhibitor EX-527 by intraperitoneal injection. The rats were treated for eight weeks. Dual-energy X-ray absorptiometry was adopted to detect changes in bone mineral density(BMD) and bone mineral content(BMC). Microscopic CT and HE staining were employed to detect microstructural damage in the femur. ELISA was employed to measure the serum levels of interleukin-10(IL-10) and transforming growth factor-β(TGF-β). Immunofluorescence staining was employed to assess the average fluorescence intensity of IL-10 and forkhead box protein P3(FoxP3) in the femur. Flow cytometry was employed to quantify the number of Treg cells in the femoral bone marrow. Immunohistochemical staining and Western blot were used to determine the protein levels of key molecules in the silent mating type information regulation 2 homolog 1(SIRT1)-mediated Janus kinase 3(JAK3)/signal transducer and activator of transcription 5(STAT5) pathway in the femur. qPCR and Western blot were used to determine the mRNA and protein levels, respectively, of bone metabolism markers osteoprotegerin(OPG) and receptor activator of nuclear factor-kappa B ligand(RANKL) in the femur. The results showed that TJC raised the BMD and BMC, alleviated the microstructural damage(P<0.05 or P<0.01) and elevated the serum levels of TGF-β and IL-10 and the average fluorescence intensity of FoxP3 and IL-10 in the femur of PMOP rats(P<0.01). Simultaneously, it increased the number of Treg cells in the femoral bone marrow(P<0.01), upregulated the mRNA level of OPG and the protein levels of SIRT1, STAT5, TGF-β, p-JAK3/JAK3, and OPG(P<0.05 or P<0.01), and downregulated the mRNA and protein levels of RANKL(P<0.01) in the femur of PMOP rats. The above results indicated that TJC could maintain bone homeostasis in PMOP rats by promoting Treg cell differentiation via modulation of SIRT1-mediated JAK3/STAT5 pathway.