[Effects of water extract of Cistanches Deserticola on bone microstructure and bone marrow immune cell subsets in SAMP6 mice].

This study aims to systematically evaluate the regulatory effects of the water extract of Cistanches Deserticola(WECD) on the bone microstructure and immune function in a mouse model of rapid aging and osteoporosis. SAMP6 mice were randomly allocated into the model, low-dose(548.73 mg·kg~(-1)) WECD, and high-dose(1 097.46 mg·kg~(-1)) WECD groups, with SAMR1 mice serving as the control group. The intervention groups were administered different doses of WECD by gavage for two months. After the experiment, the general conditions of mice were recorded. Micro-computed tomography(Micro-CT) was employed to assess the changes in bone microstructure. Hematoxylin-eosin(HE) staining was performed to observe pathological changes in the bone marrow tissue. Enzyme-linked immunosorbent assay(ELISA) was used to measure the changes in plasma bone metabolism markers. Real-time quantitative reverse transcription polymerase chain reaction(RT-qPCR) was employed to measure the expression of bone metabolism-related genes and inflammatory cytokines. Flow cytometry was used to analyze the changes in the composition of T, B, and NK cell subsets in the bone marrow. The results indicated that WECD intervention significantly improved the bone microstructure of SAMP6 mice. Compared with the control group, the model group showed decreases in bone mineral density(BGP)(P<0.05) and trabecular number(Tb.N). Compared with the model group, low-and high-dose WECD increased the BGP(P<0.01) and high-dose WECD increased the Tb.N(P<0.001). Compared with the control group, the model group showed loosely arranged intertrabecular cells and short and discontinuous trabeculae. Both low-dose and high-dose WECD treatments restored the close arrangement of bone marrow cells and the compact trabecular structure. Compared with the control group, the model group showed a decline in bone gla protein(BGP) level, while high-dose WECD attenuated the decline(P<0.05). The activities of alkaline phosphatase(ALP) and tartrate-resistant acid phosphatase-5b(TRAP-5b) were higher in the model group than in the control group, and both the low-and high-dose WECD groups showed reduced ALP and TRAP-5b activities compared with the model group(P<0.05). Additionally, compared with the control group, the expression levels of Runt-related transcription factor 2(RUNX2) and osteoprotegerin(OPG) were reduced in the model group. Although the high-dose WECD group showed an upward trend in RUNX2 and OPG levels compared with the model group, the difference was not significant, while the low-dose group showed an increasing trend(P<0.05). There was no notable difference in the expression of peroxisome proliferator-activated receptor gamma(PPARγ) among the groups. Compared with the control group, the model group exhibited elevated expression of interleukin-6(IL-6), interleukin-10(IL-10), and cyclin-dependent kinase inhibitor 2A(P16). Compared with the model group, high-dose WECD reduced the P16 expression(P<0.05). In addition, high-dose WECD significantly modulated the composition of bone marrow T cell subsets. Compared with the control group, the model group showed marked reductions in the number of na6ve na6ve CD4 positive T cells(CD4~+T cells) and the ratio of CD4 positive na6ve T cells to CD4 positive memory T cells(CD4~+ Tn/Tm), along with an increase in effector memory CD8 positive T cells(TEM CD8~+T cells)(P<0.05, P<0.01). Compared with the model group, high-dose WECD increased the number of na6ve CD4~+T cells(P<0.05), decreased TEM CD8~+T cells(P<0.05), and improved the CD4~+ Tn/Tm ratio in the bone marrow. In conclusion, WECD exhibits regulatory effects on bone microstructure in the mouse model of rapid aging and osteoporosis by enhancing the T cell function in the bone marrow.