OBJECTIVES: To explore the mechanism by which histone deacetylase 1 (HDAC1) regulates steroid-induced apoptosis of mouse osteocyte-like MLO-Y4 cells. METHODS: MLY-O4 cells were treated with 400 nmol/L trichostatin A (TSA) or 1 mmol/L dexamethasone for 24 h or transfected with a HDAC1-overexpressing vector prior to TSA or dexamethasone treatment. The changes in the expressions of HDAC1, SP1, cleaved caspase-3 and Bax, SP1 acetylation level, cell proliferation, and cell apoptosis were examined. The interaction between HDAC1 and SP1 was determined with immunoprecipitation assay and Western blotting. RESULTS: Treatment with dexamethasone significantly increased cell apoptosis, enhanced the expressions of cleaved caspase-3 and Bax, reduced HDAC1 expression, and suppressed proliferation of MLO-Y4 cells. Both TSA and dexamethasone obviously increased SP1 acetylation level and the expression of SP1 in MLO-Y4 cells. HDAC1 overexpression in the cells significantly attenuated the effect of TSA and dexamethasone, promoted cell proliferation, lowered the expressions of SP1, cleaved caspase-3 and Bax, and inhibited dexamethasone-induced cell apoptosis. Immunoprecipitation assay and Western blotting demonstrated the interaction between HDAC1 and SP1 in the cells. CONCLUSIONS HDAC1 inhibits dexamethasone-induced apoptosis and promotes proliferation of cultured mouse osteocytes by suppressing SP1 expression via promoting its deacetylation.
Animals ; Apoptosis/drug effects* ; Mice ; Histone Deacetylase 1/genetics* ; Osteocytes/drug effects* ; Sp1 Transcription Factor/metabolism* ; Acetylation ; Dexamethasone/pharmacology* ; Cell Proliferation/drug effects* ; Caspase 3/metabolism* ; Cell Line ; Hydroxamic Acids/pharmacology* ; bcl-2-Associated X Protein/metabolism*

OBJECTIVE: Glucocorticoid-induced osteoporosis (GIOP) is a common complication of prolonged glucocorticoid therapy. Chlorogenic acid (CGA), a polyphenol with antioxidant properties that is extracted from traditional Chinese medicines such as Eucommiae Cortex, has potential anti-osteoporotic activity. This study aimed to investigate the possible effects of CGA on GIOP in mice and murine long bone osteocyte Y4 (MLO-Y4) cells and explore the underlying molecular mechanisms. METHODS: The protective effects of CGA were initially evaluated in the GIOP mouse model induced by dexamethasone (Dex). The micro-computed tomography, hematoxylin-eosin staining, silver nitrate staining, and serum detection were used to assess the efficacy of CGA for improving bone formation in vivo. Then, network pharmacology analysis was used to predict the potential targets and molecular mechanisms underlying the therapeutic efficacy of CGA against GIOP. After that, 2',7'-dichlorofluorescein diacetate staining, flow cytometry, real-time quantitative reverse transcription polymerase chain reaction, and Western blotting were used to verify the mechanisms of CGA against GIOP in vitro. RESULTS: Animal experiments showed that CGA treatment effectively attenuated Dex-induced decreases in bone mass and strength and improved disrupted osteocyte morphology in mice. The protein-protein interaction analysis highlighted erb-b2 receptor tyrosine kinase (ERBB2), which is also known as human epidermal growth factor receptor 2 (HER2), caspase-3, kinase insert domain receptor, matrix metallopeptidase 9, matrix metallopeptidase 2, proto-oncogene tyrosine-protein kinase Src, and epidermal growth factor receptor as core targets. The Kyoto Encyclopedia of Genes and Genomes analysis revealed several significantly enriched pathways (P < 0.05), including the ERBB, phosphoinositide 3 kinase-AKT serine/threonine kinase 1 (AKT), and mechanistic target of rapamycin kinase (mTOR) pathways. Cellular experiments verified that CGA enhanced bone formation and promoted autophagy while inhibiting apoptosis in MLO-Y4 cells exposed to Dex, which was associated with the upregulated expression of HER2 and activation of the HER2/AKT/mTOR signaling pathway. CONCLUSION CGA exerted anti-osteoporotic effects against GIOP, partially through targeting osteocytes and modulating the HER2/AKT/mTOR signaling pathway. Please cite this article as: Xie AN, Zhang SZY, Zhang Y, Cao JL, Wang CL, Wang LB, Wu HJ, Zhang J, Dai WW. Chlorogenic acid mitigates glucocorticoid-induced osteoporosis via modulation of HER2/AKT/mTOR signaling pathway. J Integr Med. 2025; 23(6):670-682.
Animals ; Chlorogenic Acid/therapeutic use* ; Osteoporosis/metabolism* ; Signal Transduction/drug effects* ; Proto-Oncogene Proteins c-akt/metabolism* ; TOR Serine-Threonine Kinases/metabolism* ; Mice ; Glucocorticoids/adverse effects* ; Receptor, ErbB-2/metabolism* ; Proto-Oncogene Mas ; Dexamethasone/adverse effects* ; Osteocytes/drug effects* ; Osteogenesis/drug effects* ; Male ; Cell Line ; Mice, Inbred C57BL ; Humans

OBJECTIVETo study the mechanism of Huogu I formula (I) in treating osteonecrosis of femoral head.

METHODSForty-eight healthy female Leghorn chickens were randomly divided into control group, model group and Huogu I group, and each group consisted of 16 chickens. At the meantime of model establishment, chickens of the Huogu I group were administrated with decoction, while the model and control group with distilled water by gavage. At the 8th and 16th week after medication, blood samples were obtained for blood lipid detection while both sides of femoral head were harvested for the rest of examinations. Specifically, expressions of bone morphogenetic protein-2 (BMP2), transforming growth factor beta1 (TGFβ(1)), Smad4 and Smad7 were evaluated by immunohistochemistry, while expression of osteoprotegerin/receptor activator of nuclear factor kappaB ligand (OPG/RANKL) mRNA was detected by in situ hybridization.

RESULTSCompared with the control group, serum levels of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) in the model group rose significantly. Positive cell counting of BMP2, TGFβ(1), Smad4 and OPG in femoral head of the model group dropped prominently. Positive cell counting of Smad7 and RANKL increased dramatically. In contrast with the model group, levels of TC, TG and LDL-C in Huogu I group reduced significantly. Positive cell counting of BMP2, TGFβ(1), Smad4 and OPG in femoral head of the Huogu I group increased prominently. Indices of Smad7 and RANKL both decreased significantly. Especially at the 8th week, these variations were more significant.

CONCLUSIONHuogu I formula is effective in promoting repair of necrotic femoral head by regulating the expressions of BMP2, TGFβ(1), Smads and OPG/RANKL of osteoclast in femoral head.

Animals ; Bone Morphogenetic Protein 2 ; metabolism ; Bone Regeneration ; drug effects ; physiology ; Chickens ; Chondrocytes ; metabolism ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Female ; Femur Head Necrosis ; chemically induced ; drug therapy ; metabolism ; Lipid Metabolism ; physiology ; Osteocytes ; metabolism ; Osteoprotegerin ; genetics ; metabolism ; Receptor Activator of Nuclear Factor-kappa B ; genetics ; metabolism ; Smad4 Protein ; metabolism ; Smad7 Protein ; metabolism ; Steroids ; pharmacology ; Transforming Growth Factor beta1 ; metabolism

OBJECTIVETo observe the bone specimen of SANFH (steroid-induced avascular necrosis of femoral head) and the effect of Gufuhuo decoction on local apoptosis of SANFH.

METHODModel rabbits of necrosis of femoral head, made by intragluteal injection with prednisone acetate, were killed after 6 weeks to study the apoptosis by means of TUNEL.

RESULTA great number of faded osteocytes and osteoblasts existed in specimen of SANFH. There was significant difference in apoptosis indexes between model and control group, Gufuhuo decoction and Xianlinggubao group (P < 0.05).

CONCLUSIONIn the course of SANFH, the necrosis results from the interaction of apoptosis and necrosis of steroid-induced osteocytes and osteoblasts. Gufuhuo decoction has some effects on improving apoptosis and necrosis of SANFH.

Animals ; Apoptosis ; drug effects ; Drug Combinations ; Drugs, Chinese Herbal ; isolation & purification ; pharmacology ; Female ; Femur Head Necrosis ; chemically induced ; pathology ; In Situ Nick-End Labeling ; Leeches ; chemistry ; Male ; Materia Medica ; isolation & purification ; pharmacology ; Osteoblasts ; pathology ; Osteocytes ; pathology ; Plants, Medicinal ; chemistry ; Prednisone ; Rabbits ; Random Allocation