Influence of Calcium Supplementation against Fluoride-Mediated Osteoblast Impairment in Vitro: Involvement of the Canonical Wnt/β-Catenin Signaling Pathway

Interaction of osteopontin with α-lactalbumin and their synergistic effects in protecting intestinal barrier injury

With increasing emphasis on designing infant formulas to better mimic human milk，the collaborative effects of milk proteins have become a subject of great interest. Our study was designed to explore the interaction between osteopontin (OPN) and α-lactalbumin (α-LA) and their impact on intestinal barrier function. We discovered that OPN and α-LA can spontaneously combine to form an endothermic protein complex via hydrophobic interactions (pH 4.5, with an OPN to α-LA mass ratio of 1:1). This finding was corroborated through isothermal titration calorimetry and fluorescence quenching techniques. Additionally, we also employed circular dichroism and infrared spectroscopy to analyze the structure of the OPN-α-LA complex. Compared with OPN or α-LA alone, we observed that OPN-α-LA complex significantly alleviates lipopolysaccharide-induced CCD 841 CoN cells injury (p < 0.05). Specifically, OPN-α-LA complex markedly increased cell viability by 42.24 % and reduced lactate dehydrogenase release by 80.71 % (p < 0.05). As confirmed by Western blot and RT-qPCR assays, the OPN-α-LA complex could promote the proliferation of intestinal epithelial cells by activating crucial genes (β-catenin, c-Myc, and cyclin D1) within the Wnt/β-catenin signaling pathway. Moreover, the complex suppresses inflammation by decreasing pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) and increasing anti-inflammatory cytokine IL-10 (p < 0.05). Additionally, it bolsters the intestinal barrier by enhancing the expression of tight junction proteins. These findings suggest the beneficial effects of OPN-α-LA complex in alleviating intestinal barrier injury, and provide new insight into the synergistic function of milk-derived bioactive proteins.

Zebrafish larvae as a model for investigating dual effects of fluoride on bone development

Long-term excessive ingestion of fluoride is a severe public health threat globally. Skeletal fluorosis, a significant manifestation of prolonged fluoride exposure, is characterized by aberrant bone structure and alterations in bone function. However, there is currently a shortage of an efficient, fast, and easy-to-operate biological model for application in the field of fluorosis research. Zebrafish larvae, with human - like skeletal traits, high reproduction, rapid development, and transparency, are commonly used in bone disease studies. This study evaluates the potential of zebrafish larvae as a novel model for fluoride-induced bone impairment. Results showed dose-dependent differences in cranial and spinal bone mineralization in zebrafish larvae exposed to sodium fluoride (NaF). The detection results of bone formation-related indicators indicated a considerable increase in alkaline phosphatase (ALP) activity in zebrafish larvae at doses of 0.5 and 1 mg/L. Simultaneously, the expression of critical bone formation proteins (BMP2, and β-catenin) was elevated in the 1 and 4 mg/L groups, which is largely consistent with the results of cranial bone mineralization. Fluoride - exposed zebrafish also showed abnormal bone metabolism markers. The total phosphorus (TP) content in the zebrafish larvae of the 100 mg/L group was markedly reduced. The total calcium (TCa) content in the zebrafish of the NaF group zebrafish was slightly decreased, although the tartrate-resistant acid phosphatase (StrACP) activity increased. In conclusion, different fluoride doses cause osteoporosis and osteosclerosis in zebrafish larvae, linked to enhanced osteogenic and osteoclastic activities and abnormal key bone - forming protein expression.

Quercetin Simultaneously Treats Skeletal Fluorosis and Kashin-Beck Disease by Modulating HIF-1 and Ferroptosis Signaling Pathways

Excessive fluoride exposure can lead to skeletal fluorosis (SF), and selenium deficiency is one of the important pathogenic factors of Kashin-Beck disease (KBD). Although the pathogenic factors of these two diseases vary, there are many similarities in their pathogenic mechanisms on skeletal and articular cartilage lesions. There are currently no specific drugs for either disease, and investigating their shared pathogenic mechanisms may facilitate the development of new drugs for the treatment. This study found through bioinformatics technology that the HIF-1 signaling pathway and ferroptosis pathway might exert significant effects in both SF and KBD. Targeted small molecule drug prediction was conducted for the above two signaling pathways, and quercetin was screened as the best candidate therapeutic drug. Meanwhile, molecular docking and molecular dynamics simulations once again validated our screening results. In summary, quercetin may alleviate the symptoms of SF and KBD by regulating the HIF-1 signaling pathway and the ferroptosis pathway. In other words, it can attain the objective of treating two diseases simultaneously with one drug. This will provide new theoretical references for the treatment of comorbidity.

Knockdown of SMYD3 by RNA Interference Regulates the Expression of Autophagy-Related Proteins and Inhibits Bone Formation in Fluoride-Exposed Osteoblasts

This study aimed to explore the role of histone methyltransferase SET and MYND domain containing 3 (SMYD3) in bone metabolism of osteoblasts exposed to fluoride. The levels of urine fluoride, BALP, and OC and the mRNA expression of SMYD3 were determined in patients with skeletal fluorosis and non-fluoride-exposed people on informed consent. The expression of SMYD3 protein, OC contents, and BALP activities were detected in human osteoblast-like MG63 cells and rat primary osteoblasts treated with sodium fluoride (NaF) for 48 h. The autophagosomes were observed by transmission electron microscopy. Then, we knocked down SMYD3 to confirm whether it was involved in the regulation of bone formation and related to autophagy and Wnt/β-catenin pathway. We observed that OC and BALP levels in patients with skeletal fluorosis significantly increased, while the mRNA expression of SMYD3 significantly decreased in the skeletal fluorosis groups. In vitro, the OC contents, BALP activities, and expression of SMYD3 significantly increased, and many autophagosomes were observed in NaF treated osteoblasts. The downregulation of SMYD3 significantly inhibited OC contents, BALP activities, and expression of autophagy-related proteins, but with no significant changes in the Wnt/β-catenin pathway. Our results demonstrated that fluoride exposure with coal-burning pollution caused orthopedic injuries and abnormalities in the levels of OC and BALP and hindered normal bone metabolism. Silencing the SMYD3 gene could significantly reduce OC and BALP levels via inhibiting the increase in autophagy induced by fluoride.

Fluoride-Induced Autophagy and Apoptosis in the Mouse Ovary: Genomic Insights into IL-17 Signaling and Gut Microbiota Dysbiosis

Chronic fluoride (F) exposure is linked to gonadotoxicity in females, yet the underlying molecular mechanisms remain unclear. This study investigated fluoride-induced reprotoxicity using advanced genomic profiling. RNA-seq analysis identified significant activation of autophagy, apoptosis, and IL-17 signaling pathways in fluoride-exposed female mice. To explore these mechanisms, F0 pregnant mice were exposed to deionized water (control) or 100 mg/L sodium fluoride (NaF) during gestation and throughout the F1 generation (n = 16 females/group), covering puberty to weaning and maturity. NaF exposure caused significant reductions in body weight, organ coefficients, and pathological indices, with increased ovarian autophagic vacuoles, mitochondrial injuries, and elevated serum/ovary LPS levels in F1 females. qRT-PCR, fluorescent staining, biochemical assays, and Western blotting confirmed the activation of IL-17 signaling, apoptosis, and autophagy. Moreover, 16S rRNA sequencing revealed gut microbiota dysbiosis in NaF-exposed F1 females, potentially exacerbating ovary injury via serum LPS elevation. The gut dysbiosis could justify deteriorated serum LPS levels and its connection to F-induced ovary injury. These findings provide mechanistic insights into fluoride-induced reprotoxicity, emphasizing the interplay of IL-17 signaling, autophagy, and apoptosis in disrupting cellular homeostasis and suggesting potential therapeutic targets.

Regulatory cellular and molecular networks in the bone microenvironment during aging

Age-induced abnormalities in bone metabolism disrupt the equilibrium between bone resorption and formation. This largely stems from disturbances in bone homeostasis, in which signaling pathways exert a significant regulatory influence. Aging compromises the functionality of the bone marrow mesenchymal stem cells (BMSCs), ultimately resulting in tissue dysfunction and pathological aging. Age-related bone degradation primarily manifests as reduced bone formation and the increased accumulation of bone marrow fat. Cellular senescence diminishes bone cell vitality, thereby disrupting the balance of bone remodeling. Intensive osteoclast differentiation leads to the generation of more osteoclasts and increased bone resorption. This review provides insight into the impact of aging on bone, encompassing bone cell states during the aging process and bone signaling pathway transformations. It primarily delves into aging-related signaling pathways, such as the bone morphogenetic protein/Smad, Wnt/β-catenin, osteoprotegerin/receptor activator of NF-κB ligand/receptor activator of NF-κB, connexin43/miR21, and nuclear factor erythroid 2-related factor 2/antioxidant response element pathways, seeking to enhance our comprehension of crucial bone cells and their secretory phenotypes during aging. Furthermore, the precise molecular regulatory mechanisms underlying the interactions between bone signaling pathways and aging are investigated.

Polyphenols as potential preventers of osteoporosis: A comprehensive review on antioxidant and anti-inflammatory effects, molecular mechanisms, and signal pathways in bone metabolism

Osteoporosis (OP) is a skeletal disorder characterized by decreased bone density, alterations in bone microstructure, and increased damage to the bones. As the population ages and life expectancy increases, OP has become a global epidemic, drawing attention from scientists and doctors. Because of polyphenols have favorable antioxidant and anti-allergy effects, which are regarded as potential methods to prevent angiocardipathy and OP. Polyphenols offer a promising approach to preventing and treating OP by affecting bone metabolism, reducing bone resolution, maintaining bone density, and lowering the differentiation level of osteoclasts (OC). There are multiple ways in which polyphenols affect bone metabolism. This article provides an overview of how polyphenols inhibit oxidative stress, exert antibacterial effects, and prevent the occurrence of OP. Furthermore, we will explore the regulatory mechanisms and signaling pathways implicated in this process.

Fluoride-induced osteoporosis via interfering with the RANKL/RANK/OPG pathway in ovariectomized rats: Oophorectomy shifted skeletal fluorosis from osteosclerosis to osteoporosis

Osteosclerosis and osteoporosis are the two main clinical manifestations of skeletal fluorosis. However, the reasons for the different clinical manifestations are unclear. In this study, we established the fluoride (F) -exposed ovariectomized (OVX) and non-OVX rat models to assess the potential role of ovarian function loss in osteosclerosis and osteoporosis. Micro-CT scanning showed that excessive F significantly induced a high bone mass in non-OVX rats. In contrast, a low bone mass manifestation was presented in OVX F-exposed rats. Also, a prominent feature of increasing trabecular connectivity, collagen area, growth plate thickness, and reduced trabecular space was found by histopathological morphology in non-OVX F-exposed rats; an opposite result was observed in OVX F-exposed. These alterations indicated ovariectomy was a vital factor leading to osteosclerosis or osteoporosis in skeletal fluorosis. Furthermore, levels of bone alkaline phosphatase (BALP) and tartrate-resistant acid phosphatase (TRAP) increased, combined with the increasing osteoclasts number, showing a sign of high bone turnover in both OVX and non-OVX F-exposed rats. Mechanistically, oophorectomy considerably activated the RANKL/RANK/OPG signaling pathway. Meanwhile, it was discovered that upregulated NF-κB positively facilitated the accumulation of nuclear factor of activated T-cells 1 (NFATC1), significantly promoting osteoclast differentiation. To sum up, this study greatly enriched the causes of clinical skeletal fluorosis and provided a new perspective for studying the pathogenesis of skeletal fluorosis.

The Role of Trace Elements and Minerals in Osteoporosis: A Review of Epidemiological and Laboratory Findings

The objective of the present study was to review recent epidemiological and clinical data on the association between selected minerals and trace elements and osteoporosis, as well as to discuss the molecular mechanisms underlying these associations. We have performed a search in the PubMed-Medline and Google Scholar databases using the MeSH terms "osteoporosis", "osteogenesis", "osteoblast", "osteoclast", and "osteocyte" in association with the names of particular trace elements and minerals through 21 March 2023. The data demonstrate that physiological and nutritional levels of trace elements and minerals promote osteogenic differentiation through the up-regulation of BMP-2 and Wnt/β-catenin signaling, as well as other pathways. miRNA and epigenetic effects were also involved in the regulation of the osteogenic effects of trace minerals. The antiresorptive effect of trace elements and minerals was associated with the inhibition of osteoclastogenesis. At the same time, the effect of trace elements and minerals on bone health appeared to be dose-dependent with low doses promoting an osteogenic effect, whereas high doses exerted opposite effects which promoted bone resorption and impaired bone formation. Concomitant with the results of the laboratory studies, several clinical trials and epidemiological studies demonstrated that supplementation with Zn, Mg, F, and Sr may improve bone quality, thus inducing antiosteoporotic effects.

Fluoride induces hypomethylation of BMP2 and activates osteoblasts through the Wnt/β-catenin signaling pathway

BACKGROUND

Skeletal fluorosis has become a public health issue in recent years as its serious impact on patients' life expectancy. Bone morphogenetic protein 2 (BMP2) plays a key role in promoting osteogenesis. However, the mechanism of BMP2-Wnt/β-catenin axis in skeletal fluorosis needs further exploration.

METHODS

The RT-qPCR and western blot assay were carried out to examine the mRNA and protein levels. Cell viability was measured by MTT assay. A commercial ALP assay kit was used to detect ALP activities. Alizarin Red staining was performed to measure the formation of mineralized nodules. Methylation-specific PCR (MSP) was performed to measure the methylation level of BMP2.

RESULTS

Fluoride promoted the expression of osteogenic marker genes (OPN, OCN, OSX and RUNX2) and induced the proliferation and differentiation of MC3T3-E1 cells. Fluoride induced hypomethylation and high expression of BMP2. Furthermore, knockdown of BMP2 reversed the promoting effect of fluoride on osteogenic differentiation of MC3T3-E1. The expression of β-catenin, glycogen synthase kinase 3β (GSK3β), wingless/integrated 3α (Wnt3α), low-density lipoprotein receptor-related protein 5 (LRP5) and dishevelled 1 (Dv1) were increased in osteoblasts treated with fluoride, however, knockdown of BMP2 reversed this phenomenon. Simultaneous knockdown of BMP2 and β-catenin significantly inhibited the differentiation of osteoblasts induced by fluoride.

CONCLUSION

Fluoride contributed to proliferation and differentiation of osteoblasts through BMP2-Wnt/β-catenin axis, providing a feasible theoretical basis for the treatment of skeletal fluorosis.

miR-486-3p regulates CyclinD1 and promotes fluoride-induced osteoblast proliferation and activation

Fluoride is a persistent environmental pollutant, and its excessive intake contributes to skeletal and dental fluorosis. The mechanisms underlying fluoride-induced abnormal osteoblast proliferation and activation, which are related to skeletal fluorosis, have not yet been fully clarified. As important epigenetic regulators, microRNAs (miRNAs) participate in bone metabolism. On the basis of our previous miRNA-seq results and bioinformatics analysis, this study investigated the role and specific molecular mechanism of miR-486-3p in fluoride-induced osteoblast proliferation and activation via CyclinD1. Herein, in the fluoride-challenged population, we observed that miR-486-3p expression decreased while CyclinD1 and transforming growth factor (TGF)-β1 increased, and miR-486-3p level correlated negatively with the expression of CyclinD1 and TGF-β1 genes. Further, we verified that sodium fluoride (NaF) decreases miR-486-3p expression in human osteoblasts and overexpression of miR-486-3p reduces fluoride-induced osteoblast proliferation and activation. Meanwhile, we demonstrated that miR-486-3p regulates NaF-induced upregulation of CyclinD1 by directly targeting its 3'-untranslated region (3'-UTR). In addition, we observed that NaF activates the TGF-β1/Smad2/3/CyclinD1 axis and miR-486-3p mediates transcriptional regulation of CyclinD1 by TGF-β1/Smad2/3 signaling pathway via targeting TGF-β1 3'-UTR in vitro. This study, thus, contributes significantly in revealing the mechanism of miR-486-3p-mediated CyclinD1 upregulation in skeletal fluorosis and sheds new light on endemic fluorosis treatment.

7,8-Dihydroxyflavone modulates bone formation and resorption and ameliorates ovariectomy-induced osteoporosis

Imbalances in bone formation and resorption cause osteoporosis. Mounting evidence supports that brain-derived neurotrophic factor (BDNF) implicates in this process. 7,8-Dihydroxyflavone (7,8-DHF), a plant-derived small molecular TrkB agonist, mimics the functions of BDNF. We show that both BDNF and 7,8-DHF promoted the proliferation, osteogenic differentiation, and mineralization of MC3T3-E1 cells. These effects might be attributed to the activation of the Wnt/β-catenin signaling pathway as the expression of cyclin D1, phosphorylated-glycogen synthase kinase-3β (p-GSK3β), β-catenin, Runx2, Osterix, and osteoprotegerin (OPG) was all significantly up-regulated. Knockdown of β-catenin restrained the up-regulation of Runx2 and Osterix stimulated by 7,8-DHF. In particular, blocking TrkB by its specific inhibitor K252a suppressed 7,8-DHF-induced osteoblastic proliferation, differentiation, and expression of osteoblastogenic genes. Moreover, BDNF and 7,8-DHF repressed osteoclastic differentiation of RAW264.7 cells. The transcription factor c-fos and osteoclastic genes such as tartrate-resistant acid phosphatase (TRAP), matrix metalloprotein-9 (MMP-9), Adamts5 were inhibited by 7,8-DHF. More importantly, 7,8-DHF attenuated bone loss, improved trabecular microarchitecture, tibial biomechanical properties, and bone biochemical indexes in an ovariectomy (OVX) rat model. The current work highlights the dual regulatory effects that 7,8-DHF exerts on bone remodeling.

Expression of Autophagy-Related Factors LC3A and Beclin 1 and Apoptosis-Related Factors Bcl-2 and BAX in Osteoblasts Treated With Sodium Fluoride

OBJECTIVE

This study aims to analyze the expressions of autophagy-related factors light chain 3 alpha (LC3A) and Beclin 1 and apoptosis-related factors B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X (BAX) in primary osteoblasts treated with sodium fluoride (NaF).

METHODS

Osteoblasts were extracted from Sprague-Dawley rats and treated with 0, 2.5, 5, and 10 mg/L NaF solutions, followed by 10 mmol/L 3-methyladenine (3-MA) for 24 h. The apoptotic rate was determined by flow cytometry, and the expressions of the autophagy- and apoptosis-related factors were measured by western blotting and real-time quantitative polymerase chain reaction.

RESULTS

The mRNA expressions of LC3A, Beclin 1, and BAX in the NaF-treated osteoblast group were higher than those in the control group, while the protein expressions of these factors in the NaF-treated group were significantly higher than those in the control group. However, the Bcl-2 protein expression in the NaF-treated osteoblasts was significantly decreased compared to that in the control cells. After the 3-MA treatment, the protein expressions of LC3A, Beclin 1, and Bcl-2 were significantly decreased compared with those of the NaF-treated group, whereas the expression of BAX increased. Moreover, the apoptosis rate was increased after the addition of the 3-MA inhibitor.

CONCLUSION

NaF stimulation promoted autophagy and apoptosis of the osteoblasts, suggesting the involvement of fluoride damage in these processes.

Dkk1 inhibits malignant transformation induced by Bmi1 via the β-catenin signaling axis in WB-F344 oval cells

Dickkopf-1 (Dkk1) is an inhibitor of Wnt signaling involved in cancer cell proliferation, apoptosis, and migration and angiogenesis. It was previously reported that B cell-specific Moloney mouse leukemia virus integration site 1 (Bmi1) activates the Wnt pathway by inhibiting the expression of DKK1 in breast cancer cell lines and 293T cells. Bmi1 and DKK1 are highly expressed in liver samples taken by biopsy from patients with hepatitis B virus-related hepatocellular carcinoma (HCC), but the effect of both Bmi1 and DKK1 on the carcinogenesis of adult hepatic stem cells (oval cells) has not previously been reported. In this study, we used WB-F344 cells to explore the function and regulation of Dkk1 upon Bmi1 treatment. Overexpression of Dkk1 repressed differentiation, proliferation, and migration induced by Bmi1 but promoted the apoptosis of hepatic WB-F344 oval cells. In addition, Dkk1 reduced the enhancement of β-catenin levels induced by Bmi1. Finally, we used transcriptome sequencing to perform a comprehensive evaluation of the transcriptome-related changes in WB-F344 oval cells induced by Dkk1 and Bmi1. These results may provide evidence for future studies of the pathogenesis of HCC and the design of possible therapies.

Effects of Different Doses of Calcium on the Mitochondrial Apoptotic Pathway and Rho/ROCK Signaling Pathway in the Bone of Fluorosis Rats

For this study, we investigate more deeply the effect calcium (Ca) develops on the mechanism underlying fluoride-triggered osteocyte apoptosis. We detected the morphology of osteocytes by HE staining, mitochondrial microstructure by using the transmission electron microscope, and the biochemical indexes related to bone metabolism and the expression of apoptosis-related genes. These results showed that NaF brought out the reduced osteocytes and ruptured mitochondrial outer membrane, with a significantly increased StrACP activity by 10.414 IU/L at the 4th week (P < 0.05), markedly upregulating the mRNA expression of Bax, Cyto-C, Apaf-1, caspase-7, ROCK-1, BMP-2, and BGP (P < 0.01), as well as caspase-6 (P < 0.05), while downregulating Bcl-2 by 61.3% (P < 0.01). Through immunohistochemical analysis, we also found that NaF notably increased the protein expression of ROCK-1 (P < 0.05) and Cyto-C, BMP-2, and BGP (P < 0.01), suggesting that NaF triggered the activation of the mitochondrial apoptotic pathway and Rho/ROCK signaling pathway. Nevertheless, 1% Ca supplementation in diet notably enhanced the mRNA expression of Bcl-2 by 39.3% (P < 0.01), thus blocking the increment of the expression of mitochondrial apoptotic pathway-related genes and ROCK-1. Meanwhile, Ca could attenuate the StrACP activity by 10.741 IU/L at the 4th week (P < 0.05) and protect the integrity of the mitochondrial outer membrane. These findings strongly suggest that 1% Ca abated the mitochondrial apoptosis pathway by increasing the anti-apoptotic gene Bcl-2 expression, and effectively inhibited the hyper-activation of ROCK-1, dually protecting the structural integrity of the mitochondrial outer membrane and maintaining normal cellular metabolic function.

Prostate cancer-secreted CCN3 uses the GSK3β and β-catenin pathways to enhance osteogenic factor levels in osteoblasts

Prostate cancer osteoblastic bone metastases are incurable and associated with chronic bone pain and a high mortality rate. Osteoclast-targeting drugs intended to prevent skeletal-related events associated with prostate cancer bone metastases do not prolong overall survival. Improved understanding of the bone-derived factors that contribute to prostate cancer osteoblastic bone metastases is required to design treatments that will improve morbidities and overall survival. Activated osteoblasts stimulate prostate cancer growth in bone. In this study, we report that prostate cancer conditioned medium (CM) promoted bone morphogenetic protein (BMP)-2, -4 and -7 production and the expression of osteogenic transcription factors Runx2 and osterix in osteoblasts. Treating the prostate cancer CM with antibody against CCN3 (nephroblastoma-overexpressed), a cysteine-rich protein that belongs to the CCN family, reduced all of these increases. Incubation of osteoblasts with CCN3 facilitated phosphorylation of GSK3β and β-catenin. GSK3β and β-catenin inhibitors or siRNAs all abolished CCN3-induced promotion of BMPs, Runx2 and osterix expression in osteoblasts. Our results indicate that prostate cancer-secreted CCN3 enhances BMP, Runx2 and osterix expression in osteoblasts via the GSK3β and β-catenin signaling pathways. This understanding of the role played by CCN3 in osteoblastic prostate bone metastasis may lead to more efficient targeted therapies.

Calcium relieves fluoride-induced bone damage through the PI3K/AKT pathway

Bone is the main target of fluorosis, and it has been perfectly elaborated that a moderate dosage of calcium (Ca) can alleviate bone fluorosis. However, whether Ca can alleviate fluorosis through the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) signaling pathway has not yet been reported. Hence, we evaluated the histopathological structure, the imbalance of the biochemical index of bone metabolism, and the expression levels of PI3K/AKT apoptosis signaling pathway-related genes in rats treated with sodium fluoride (NaF, F) and/or calcium carbonate (CaCO3) for 120 days. Our results suggest that 100 mg L-1 NaF induced histopathological injury as alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (StrACP) activity increased, with a decrease in the serum Ca levels (p < 0.05). Moreover, the results of qRT-PCR and western blotting showed that F increased the expression levels of transglutaminase 2 (TGM2), focal adhesion kinase (FAK), PI3K, AKT, forkhead box O1 (Foxo1), Bcl-2 interacting mediator of cell death (BIM), Bcl2-associated x protein (Bax) and Caspase 3 (p < 0.05, p < 0.01). It also decreased the expression of AnnexinA5 (Anxa5), 3'-phosphoinositide-dependent kinase 1 (PDK1) and B-cell lymphoma-2 (Bcl-2) (p < 0.05, p < 0.01), which finally activated the PI3K/AKT pathway. On the other hand, CaCO3 supplementation reversed the histopathological injury along with the levels of ALP, StrACP and serum Ca, alleviating the gene expression levels of PI3K/AKT pathway-related markers. Altogether, we can conclude that CaCO3 supplementation mitigated F-induced bone damage via the PI3K/AKT signaling pathway.

Salvianolic acid B promotes the osteogenic differentiation of human periodontal ligament cells through Wnt/β-catenin signaling pathway

BACKGROUND

Osteogenic differentiation of human periodontal ligament cells (hPDLCs) is crucial for regenerate periodontal tissues. In this study, we investigated the function of salvianolic acid B (Sal B) in osteogenesis of hPDLCs.

METHODS

HPDLCs were isolated from healthy third molar roots. HPDLCs at passage 3 were identified by morphological observation and immunohistochemistry of vimentin. The viability of hPDLCs incubated with Sal B at concentrations of 0μM, 0.1μM, 0.5μM, 1μM and 5μM were measured by CCK-8 assay. To evaluate the effect of Sal B on osteogenic differentiation of hPDLCs, the alkaline phosphatase (ALP) activity, osteogenic differentiation markers, and mineralized nodules were determined by ALP kit, qRT-PCR and alizarin red S staining, respectively. To confirm the function of Sal B in hPDLCs involved in Wnt/β-catenin signaling pathway, hPDLCs were incubated with Sal B or co-incubated with Sal B and DKK-1 (a inhibitor of Wnt/β-catenin). The levels of Wnt/β-catenin signaling pathway and osteogenic differentiation-associated indicators were then determined.

RESULTS

HPDLCs showed a typical fibroblast-like and spindle-shaped, with vimentin-positive. The viability of hPDLCs had no obvious change with stimulation of Sal B at various doses. Sal B promoted the increase of ALP activity, osteogenic differentiation markers levels, mineralized nodules and activation of Wnt/β-catenin signaling pathway, and DKK-1 could block those effects of Sal B on hPDLCs.

CONCLUSION

Sal B promoted osteogenesis of hPDLCs through Wnt/β-catenin signaling pathway, which providing a potential drug for periodontitis treatment.