Employing different types of phytoestrogens improve bone mineralization in bisphenol A stimulated osteoblast

Bisphenol A (BPA) and Cardiovascular or Cardiometabolic Diseases

Bisphenol A (BPA; 4,4'-isopropylidenediphenol) is a well-known endocrine disruptor. Most human exposure to BPA occurs through the consumption of BPA-contaminated foods. Cardiovascular or cardiometabolic diseases such as diabetes, obesity, hypertension, acute kidney disease, chronic kidney disease, and heart failure are the leading causes of death worldwide. Positive associations have been reported between blood or urinary BPA levels and cardiovascular or cardiometabolic diseases. BPA also induces disorders or dysfunctions in the tissues associated with these diseases through various cell signaling pathways. This review highlights the literature elucidating the relationship between BPA and various cardiovascular or cardiometabolic diseases and the potential mechanisms underlying BPA-mediated disorders or dysfunctions in tissues such as blood vessels, skeletal muscle, adipose tissue, liver, pancreas, kidney, and heart that are associated with these diseases.

Modulation of Osteogenic Gene Expression by Human Osteoblasts Cultured in the Presence of Bisphenols BPF, BPS, or BPAF

Bone effects attributed to bisphenols (BPs) include the inhibition of growth and differentiation. This study analyzes the effect of BPA analogs (BPS, BPF, and BPAF) on the gene expression of the osteogenic markers RUNX2, osterix (OSX), bone morphogenetic protein-2 (BMP-2), BMP-7, alkaline phosphatase (ALP), collagen-1 (COL-1), and osteocalcin (OSC). Human osteoblasts were obtained by primary culture from bone chips harvested during routine dental work in healthy volunteers and were treated with BPF, BPS, or BPAF for 24 h at doses of 10^-5, 10^-6, and 10^-7 M. Untreated cells were used as controls. Real-time PCR was used to determine the expression of the osteogenic marker genes RUNX2, OSX, BMP-2, BMP-7, ALP, COL-1, and OSC. The expression of all studied markers was inhibited in the presence of each analog; some markers (COL-1; OSC, BMP2) were inhibited at all three doses and others only at the highest doses (10^-5 and 10^-6 M). Results obtained for the gene expression of osteogenic markers reveal an adverse effect of BPA analogs (BPF, BPS, and BPAF) on the physiology of human osteoblasts. The impact on ALP, COL-1, and OSC synthesis and therefore on bone matrix formation and mineralization is similar to that observed after exposure to BPA. Further research is warranted to determine the possible contribution of BP exposure to the development of bone diseases such as osteoporosis.

S-Equol enhances osteoblastic bone formation and prevents bone loss through OPG/RANKL via the PI3K/Akt pathway in streptozotocin-induced diabetic rats

Background

This study aimed to explore whether S-Equol delays diabetes-induced osteoporosis and the molecular mechanisms underlying its therapeutic effects.

Materials and methods

Thirty-five male Sprague–Dawley rats were randomized into five groups. The diabetic osteoporosis (DOP) group and three S-Equol treatment groups were intraperitoneally injected with streptozotocin (STZ) to develop a DOP model. After the 12-week intervention, bone transformation indicators were detected using an enzyme-linked immunosorbent assay kit; bone mineral density (BMD) and bone microstructure were obtained using dual-energy X-ray absorptiometry and microCT; morphological changes in the bone tissue were investigated using HE staining; bone morphogenetic proteins were detected using immunohistochemical staining. ROS17/2.8 cells were cultured in vitro, and Cell Counting Kit-8 was used to test the protective effects of S-Equol in osteoblastic cells in a high-fat and high-glucose environment. Furthermore, the expression of osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), estrogen receptor β(ERβ), phosphorylated Akt (pAKT)/protein kinase B (AKT), and osteocalcin (OC) in bone tissue and ROS17/2.8 cells was assessed using reverse transcription polymerase chain reaction (RT-PCR) and western blotting. To determine whether ERβ and phosphatidylinositol 3’ -kinase (PI3K)/AKT signaling pathways are involved in the process, LY294002 (PI3K signaling pathway inhibitor) and small interfering RNA targeting ERβ mRNA (si-ERβ) were used to verify the function of the ERβ-mediated PI3K/AKT pathway in this process.

Results

After the 12-week intervention, S-Equol enhanced BMD, improved bone microarchitecture in DOP rats (P < 0.05), and improved markers of bone metabolism (P < 0.05). In vitro, 10^–6 mmol/L S-Equol was selected to significantly protect osteoblasts from high- and high-glucose environments (P < 0.05). Gene expression of OPG, ERβ, pAKT/AKT, and OC was upregulated compared to the DOP group, and RANKL was downregulated compared to the DOP group (P < 0.05) both in bone tissue and osteoblastic cells. The promotion of OPG and pAKT/AKT is mediated by LY294002 and siERβ.

Conclusion

S-Equol binds to ERβ to regulate OPG/RANKL via the PI3K/AKT pathway and improve DOP. Our results demonstrate the potential role of S-Equol in the treatment of DOP by targeting ERβ. Thus, S-Equol may have the potential to be an adjuvant drug for treating DOP.

Repercussions of Bisphenol A on the Physiology of Human Osteoblasts

(1) Background: Bisphenol A (BPA) is an endocrine disruptor that is widely present in the environment and exerts adverse effects on various body tissues. The objective of this study was to determine its repercussions on bone tissue by examining its impact on selected functional parameters of human osteoblasts. (2) Methods: Three human osteoblast lines were treated with BPA at doses of 10^-5, 10^-6, or 10^-7 M. At 24 h post-treatment, a dose-dependent inhibition of cell growth, alkaline phosphatase activity, and mineralization was observed. (4) Results: The expression of CD54 and CD80 antigens was increased at doses of 10^-5 and 10^-6 M, while the phagocytic capacity and the expression of osteogenic genes (ALP, COL-1, OSC, RUNX2, OSX, BMP-2, and BMP-7) were significantly and dose-dependently reduced in the presence of BPA. (5) Conclusions: According to these findings, BPA exerts adverse effects on osteoblasts by altering their differentiation/maturation and their proliferative and functional capacity, potentially affecting bone health. Given the widespread exposure to this contaminant, further human studies are warranted to determine the long-term risk to bone health posed by BPA.

[Estradiol activates ERK phosphorylation by binding to ERβ to inhibit proliferation and promote apoptosis of human chondrocytes]

OBJECTIVE

To explore the effect of estradiol (E2) binding to its receptor ERβ on the proliferation and apoptosis of C28I2 cells.

OBJECTIVE

We cloned the sequence of ESR2 into a recombinant adenovirus plasmid (pAd-ESR2) and packaged the plasmid in HEK293 cells. Normal human chondrocyte C28I2 cells were transfected with Ad-ESR2 or small interfering RNA targeting ESR2-siRNA (ESR2-siRNA), and the effects of treatment with DMSO or E2 on the expression of the proteins associated with endoplasmic reticulum (ER) stress and cell apoptosis were determined using Western blotting. qRT-PCR was used to detect the expressions of proliferation-related marker genes, and an EdU kit and flow cytometry were used to assess cell proliferation and apoptosis. We also tested the effects of U0126 (an ERK pathway inhibitor) and E2, alone or in combination, on ER stress, apoptosis and the ERK signaling pathway in C28I2 cells infected with Ad-ESR2 using Western blotting.

OBJECTIVE

Overexpression of Ad-ESR2 in C28I2 cells significantly promoted the expressions of IRE1α, PERK, XBP1s, and cleaved caspase-12, inhibited proliferation related marker genes PCNA, cyclin B1, cyclin D1, and decreased the level of ERK phosphorylation following E2 treatment (all P < 0.05). Interference of ESR2 caused significant reduction in the expressions of ER stress-related proteins and apoptosis-related proteins, up-regulated the genes related to cell proliferation, and increased intracellular pERK/ERK ratio in C28I2 cells. The effect of E2 binding to ERβ, which promoted the expressions of ER stress associated proteins and apoptosis related proteins, was obviously antagonized by treatment of the cells with U0126.

OBJECTIVE

The binding of E2 to ERβ promotes ER stress and apoptosis in human chondrocytes by activating ERK pathway phosphorylation inhibit cell proliferation.

Genistein Improves Bone Healing via Triggering Estrogen Receptor Alpha-Mediated Expressions of Osteogenesis-Associated Genes and Consequent Maturation of Osteoblasts

Osteoporosis-associated fractures may cause higher morbidity and mortality. Our previous study showed the effects of genistein, a phytoestrogen, on the induction of estrogen receptor alpha (ERα) gene expression and stimulation of osteoblast mineralization. In this study, rat calvarial osteoblasts and an animal bone defect model were used to investigate the effects of genistein on bone healing. Treatment with genistein caused a time-dependent increase in alkaline phosphatase (ALP) activity in rat osteoblasts. Levels of cytosolic and nuclear ERα significantly augmented following exposure to genistein. Subsequently, genistein elevated levels of ALP mRNA and protein in rat osteoblasts. Moreover, genistein induced other osteogenesis-associated osteocalcin and Runx2 mRNA and protein expressions. Knocking-down ERα using RNA interference concurrently inhibited genistein-induced Runx2, osteocalcin, and ALP mRNA expression. Attractively, administration of ICR mice suffering bone defects with genistein caused significant increases in the callus width, chondrocyte proliferation, and ALP synthesis. Results of microcomputed tomography revealed that administration of genistein increased trabecular bone numbers and improved the bone thickness and volume. This study showed that genistein can improve bone healing via triggering ERα-mediated osteogenesis-associated gene expressions and subsequent osteoblast maturation.