Protective Effects of Punicalagin on Osteoporosis by Inhibiting Osteoclastogenesis and Inflammation via the NF-κB and MAPK Pathways

Tubson-2 decoction ameliorates rheumatoid arthritis complicated with osteoporosis in CIA rats involving isochlorogenic acid A regulating IL-17/MAPK pathway

BACKGROUND

Osteoporosis (OP) is considered as one of the major comorbidities of rheumatoid arthritis (RA), and is responsible for fragility fracture. However, there is currently no effective treatment for RA complicated with OP. Tubson-2 decoction (TBD), a Mongolian medicine also known as Erwei Duzhong Decoction, has been shown to exert a preventive effect on post-menopausal osteoporosis (PMOP). The preventive effects of TBD on RA-induced OP, as well as the bioactive compound responsible and the underlying mechanisms, remain to be elucidated.

OBJECTIVE

To explore the effects of TBD on RA-induced OP in vivo, and to elucidate the mechanism of isochlorogenic acid A (ICA), the effective component of TBD, in vitro.

METHODS

To evaluate the anti-arthritic and anti-osteoporotic effects of TBD, we conducted H&E straining and safranine O/fast green, TEM, immunohistochemistry (IHC), bone histomorphometry, micro-CT imaging, and biomechanical testing in collagen induced arthritis (CIA) rats. The active ingredient in TBD was identified using network pharmacology and molecular docking. The identification was supported by in vivo IHC assay, and further confirmed using qRT-PCR, Western blot, and SEM analysis in TNF-α-treated MH7A cells and/or in LPS-exposed RAW264.7 cells.

RESULTS

Oral administration of TBD attenuated the severity of arthritis and osteopenia as well as poor bone quality, in CIA rats. Additionally, TBD and the positive control, tripterygium glycosides (TG), exhibited similar effects in reducing inflammation in both the synovium and ankle joint. They also were both effective in improving bone loss, microarchitecture, and overall bone quality. TBD reduced the expression of MMP13, IL-17, and p-JNK protein in the synovium of CIA rats. ICA, which was screened, suppressed TNF-α or LPS-triggered inflammatory responses via down-regulating IL-17 signaling, involving in MMP13, IL-1β, IL-23, and IL-17, and the MAPK pathway including p-ERK, p-JNK, and p-P38, both in MH7A cells and in RAW264.7 cells. Furthermore, ICA prevented osteoclasts from differentiating and bone resoprtion in a dose-dependent manner in vitro.

CONCLUSION

This study provides the first evidence that TBD exerts intervening effects on RA-induced OP, possibly through the downregulation of the IL-17/MAPK signaling pathway by ICA. The findings of our study provides valuable insights for further research in this area.

Association between fibrinogen and bone mineral density in postmenopausal women

OBJECTIVE

There is very limited of evidence linking fibrinogen and bone mineral density (BMD) in postmenopausal women. Therefore, this study intended to examine the relationship between fibrinogen and total BMD in postmenopausal women.

METHODS

This cross-sectional analysis included 2043 postmenopausal women aged 50 years and older from the 1999 to 2002 National Health and Nutrition Examination Survey. The independent variable was fibrinogen and the outcome variable was total BMD. The association between fibrinogen and total BMD in postmenopausal women was examined using multivariate linear regression models, with subgroup analyses stratified by race. Smoothing curve fitting and generalized additive models further analyzed the sample data.

RESULTS

In multiple regression models adjusted for potential confounders, fibrinogen was negatively associated with total BMD (model 1: - 0.0002 [- 0.0002, - 0.0001], model 2: - 0.0000 [- 0.0001, - 0.0000], model 3: - 0.0001 [- 0.0001, - 0.0001]). In subgroup analysis stratified by race, fibrinogen levels were negatively associated with total BMD in postmenopausal women, Non-Hispanic Whites, and Mexican Americans. However, in Non-Hispanic Blacks, the correlation between fibrinogen levels and total BMD was not significant. For individuals that identify as Other Races, fibrinogen levels were positively correlated with total BMD.

CONCLUSION

Our findings show a negative association between fibrinogen levels and total BMD in most postmenopausal women aged 50 years and older, however, is variable by race. In postmenopausal women, Non-Hispanic Whites and Mexican Americans, relatively high fibrinogen levels may be adverse to bone health.

Maresin1: A multifunctional regulator in inflammatory bone diseases

Inflammation plays a crucial role in the physical response to danger signals, the elimination of toxic stimuli, and the restoration of homeostasis. However, dysregulated inflammatory responses lead to tissue damage, and chronic inflammation can disrupt osteogenic-osteoclastic homeostasis, ultimately leading to bone loss. Maresin1 (MaR1), a member of the specialized pro-resolving mediators (SPMs) family, has been found to possess significant anti-inflammatory, anti-allergic, pro-hemolytic, pro-healing, and pain-relieving properties. MaR1 is synthesized by macrophages (Mφs) and omega-3 fatty acids, and it may have the potential to promote bone homeostasis and treat inflammatory bone diseases. MaR1 has been found to stimulate osteoblast proliferation through leucine-rich repeat G protein-coupled receptor 6 (LGR6). It also activates Mφ phagocytosis and M2-type polarization, which helps to control the immune system. MaR1 can regulate T cells to exert anti-inflammatory effects and inhibit neutrophil infiltration and recruitment. In addition, MaR1 is involved in antioxidant signaling, including nuclear factor erythroid 2-related factor 2 (NRF2). It has also been found to promote the autophagic behavior of periodontal ligament stem cells, stimulate Mφs against pathogenic bacteria, and regulate tissue regeneration and repair. In summary, this review provides new information and a comprehensive overview of the critical roles of MaR1 in inflammatory bone diseases, indicating its potential as a therapeutic approach for managing skeletal metabolism and inflammatory bone diseases.

Network pharmacology-based strategy to investigate pharmacological mechanism of Liuwei Dihuang Pill against postmenopausal osteoporosis

Postmenopausal osteoporosis (PMOP) has became 1 of most prevalent bone disorders with aging population. Liuwei Dihuang (LWDH) Pill, a classical kidney-tonifying prescription, is extensively used to treat PMOP in China. The aim of this study is to explore the pharmacological mechanisms of LWDH Pill against PMOP via network pharmacological strategy. The active ingredients of LWDH Pill were screened out from the Traditional Chinese Medicine System Pharmacology, Encyclopedia of Traditional Chinese Medicine and Bioinformatics Analysis Tool for Molecular mechANism of Traditional Chinese Medicine Databases, and their related target genes were fished in the UniProt database. Simultaneously, the GeneCards and DisGeNET databases were used to identify the target genes of PMOP. Through establishing a protein-protein interaction network, the overlapping genes between LWDH Pill and PMOP were identified to analyze their interactions and the hub target genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed to predict the underlying biological processes (BP) and signaling pathways, respectively. A total of 64 active ingredients and 653 related target genes were identified in LWDH Pill, and 292 target genes were closely associated with PMOP. After matching the target genes between LWDH Pill and PMOP, 84 overlapping targets were obtained and considered as therapeutically relevant. Through construction of a protein-protein interaction network, we identified 20 hub target genes including IL6, INS, tumor necrosis factor, AKT1, vascular endothelial growth factor A, IGF1, TP53, IL1B, MMP9, JUN, LEP, CTNNB1, EGF, PTGS2, PPARG, CXCL8, IL10, CCL2, FOS and ESR1. Gene Ontology enrichment analysis suggested that LWDH Pill exerted anti-PMOP effects via regulating multiple BP including cell proliferation and apoptosis, oxidative stress, inflammation and angiogenesis. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed several pathways, such as PI3K-AKT pathway, mitogen-activated protein kinase pathway, hypoxia-inducible factors-1 pathway, tumor necrosis factor pathway, interleukin-17 (IL-17) pathway and FoxO pathway that might be involved in modulating the above BP. Through network pharmacological approach, we investigated the potential therapeutic mechanism of LWDH Pill against postmenopausal osteoporosis in a systemic perspective. These identified multi-targets and multi-pathways provide promising directions for further revealing more exact mechanisms.

Nutraceuticals for Complementary Treatment of Multisystem Inflammatory Syndrome in Children: A Perspective from Their Use in COVID-19

Multisystem inflammatory syndrome in children (MIS-C) has been widely reported in some children diagnosed with SARS-CoV-2. Clinical signs of MIS-C are manifested at 2 to 4 weeks after SARS-CoV-2 infection, where elevated biomarkers of inflammation and cardiac dysfunction are the hallmark of this syndrome when infection or exposure to SARS-CoV-2 has been confirmed. However, after two years of acknowledgment, MIS-C treatment is still under research to reach safety and effectiveness in the acute phase in children. Therefore, in this review, we discuss the potential use of natural compounds with antioxidant and anti-inflammatory effects to reduce collateral damage caused by hyperinflammation in MIS-C pathology for new research in treatment and interventions.

Higher modified dietary inflammatory index is associated with increased risk of osteoporosis in US adults: Data from NHANES

Objective

The aim of this study was to study the relationship between modified dietary inflammatory index (MDII) score with osteoporosis (OP) in adult Americans.

Methods

Data were extracted from the United States National Health and Nutrition Examination Survey (NHANES) (2007–2008, 2009–2010, 2013–2014, and 2017–2018). In this cross-sectional study, 5,446 participants were included and analyzed. Potential dietary inflammatory was assessed by MDII score (24-h recall), a composite method computed according to the relationship between nutrients and systemic pro-inflammatory cytokine level, and was further classified into tertiles. Weighted multivariable logistic regression analysis was employed to examine the associations between OP and MDII scores.

Results

In weighted multivariable-adjusted logistic regression models, the highest tertile of MDII score was associated with an increased risk of OP [odds ratio (OR): 1.73, 95% confidence interval (95 CI%): 1.14–2.63]. In participants aged above 59 years, a higher MDII score showed a higher risk of OP (OR: 1.92; 95 CI%: 1.16–3.15). In the sex-stratified models, the results remained significant only among women (OR: 1.80; 95% CI: 1.02–3.17). In the menopausal status stratified model, after adjusting potential confounding variables, the association between the MDII score, either as a categorical (OR: 1.88; 95% CI: 1.07–3.13) or continuous variables (OR: 1.19; 95%CI: 1.02–1.38), and OP risk was significant among postmenopausal women.

Conclusion

Our study indicates that a higher MDII score (pro-inflammatory effect) is significantly associated with an increased risk of OP in US adults, especially among those postmenopausal women more than 60 years. This study further supports that those dietary changes have the potential to prevent OP.

Alpinetin ameliorates bone loss in LPS-induced inflammation osteolysis via ROS mediated P38/PI3K signaling pathway

BACKGROUND AND OBJECTIVE

Bone loss occurs in several inflammatory diseases because of chronic persistent inflammation that activates osteoclasts (OCs) to increase bone resorption. Currently available antiresorptive drugs have severe side effects or contraindications. Herein, we explored the effects and mechanism of Alpinetin (Alp) on receptor activator of nuclear factor κB ligand (RANKL)-mediated OCs differentiation, function, and in inflammatory osteolysis of mice.

METHOD

Primary mouse bone marrow-derived macrophages (BMMs) induced by RANKL and macrophage colony-stimulating factor (M-CSF) were utilized to test the impact of Alp on OCs differentiation, function, and intracellular reactive oxygen species (ROS) production, respectively. Expression of oxidant stress relevant factors and OCs specific genes were assessed via real-time quantitative PCR. Further, oxidative stress-related factors, NF-κB, MAPK, PI3K/AKT/GSK3-β, and NFATc1 pathways were examined via Western blot. Finally, LPS-induced mouse calvarial osteolysis was used to investigate the effect of Alp on inflammatory osteolysis in vivo.

RESULT

Alp suppressed OCs differentiation and resorption function, and down-regulated the ROS production. Alp inhibited IL-1β, TNF-α and osteoclast-specific gene transcription. It also blocked the gene and protein expression of Nox1 and Keap1, but enhanced Nrf2, CAT, and HO-1 protein levels. Additionally, Alp suppressed the phosphorylation of PI3K and P38, and restrained the expression of osteoclast-specific gene Nfatc1 and its auto-amplification, hence minimizing LPS-induced osteolysis in mice.

CONCLUSION

Alp is a novel candidate or therapeutics for the osteoclast-associated inflammatory osteolytic ailment.

Punicalagin suppresses inflammation in ventilator-induced lung injury through protease-activated receptor-2 inhibition-induced inhibition of NLR family pyrin domain containing-3 inflammasome activation

Punicalagin is recorded to be a potent anti-inflammatory drug, while its effect on inflammation existing in ventilator-induced lung injury (VILI) requires further verification. Rats were pretreated with punicalagin, followed by VILI modeling. Lung histopathological examination was performed with hematoxylin-eosin staining accompanied by the lung injury score. The lung wet/dry (W/D) weight ratio and total bronchoalveolar lavage fluid (BALF) protein level were measured. After transfection with protease-activated receptor-2 (PAR2) overexpression plasmids, mouse alveolar epithelial MLE-12 cells were treated with punicalagin and then subjected to cyclic stretching. Punicalagin's cytotoxicity to MLE-12 cells were measured by MTT assay. The levels of inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6), PAR2, NLR family pyrin domain containing-3 (NLRP3), and apoptosis-associated speck-like protein containing a CARD (ASC) in the BALF, lung tissues or cells were analyzed by enzyme-linked immune-sorbent assay (ELISA), qRT-PCR or/and western blot. Punicalagin treatment attenuated VILI-induced lung histopathological changes and counteracted VILI-induced increases in the lung injury score, W/D weight ratio and total protein level in BALF. Also, punicalagin treatment counteracted in vivo VILI/cyclic stretching-induced increases in the levels of PAR2, inflammatory cytokines, NLRP3, and ASC. PAR2 overexpression potentiated the cyclic stretching-induced effects, while punicalagin treatment revoked this PAR2 overexpression-induced potentiation effect. In turn, PAR2 overexpression partly resisted the punicalagin treatment-induced counteractive effects on the cyclic stretching-induced effects. Punicalagin suppresses inflammation in VILI through PAR2 inhibition-induced inhibition of NLRP3 inflammasome activation.

Shu-Di-Huang and Gan-Cao Herb Pair Restored the Differentiation Potentials of Mesenchymal Stem Progenitors in Treating Osteoporosis via Downregulation of NF-κB Signaling Pathway

Background

Shu-Di-Huang (Radix Rehmanniae Praeparata, RR) and Gan-Cao (liquorice, L) are frequently used traditional Chinese herb pair in treating osteoporosis (OP). However, the exact mechanism of the RR and L herb pair (RR-L) remains unclear. To explore the efficacy and possible mechanisms of RR-L in treating OP, in silico, in vitro, and in vivo experiments were conducted in the current study.

Methods

In silico, potential therapeutic target genes and active chemical compounds of RR-L herb pair were predicted and constructed into a network. In vivo, 30 Sprague Dawley rats were divided into 3 groups, including the sham group, the OP model group, and the RR-L-treated OP group. Micro-CT and pathological sections were conducted to validate the therapeutic effects of RR-L in treating OP. MSCs of rats were isolated and cultured in vitro to validate the mesenchymal stem cells (MSCs) related phenotype changes, including Alizarin red staining, Oil red staining, and immunofluorescence. In vitro, cell proliferation analysis, Alizarin red staining, Oil red staining, immunofluorescence of NF-κB, and protein expression of PPARγ, RUNX2, OCN, and p65 were conducted on MSCs to explore the RR-L containing serum in vitro. Also, activator and inhibitor of NF-κB signaling pathway were introduced to determine the possible mechanism of RR-L in the treatment of OP via enhancing MSCs proliferation and differentiation.

Results

In silico, 168 chemical compounds with a property of oral bioavailability ≥30% and drug-likeness ≥0.18 were recognized as potentially active compounds in RR-L and 249 genes were found to be the targets of which. Among them, 120 genes were found to be therapeutic genes of RR-L in treating OP and KEGG and GO analysis of which demonstrated that RR-L involves in lipid metabolism and multiple inflammation-related signaling pathways. In vivo, ovariectomy- (OVX-) induced OP phenotypes in Sprague Dawley rats include bone mineral density and microarchitecture damaging, abnormal bone metabolism, upregulation of inflammation markers, and damaged differentiation potential of MSCs. Treatment of RR-L reversed the trend and restored the differentiation potential of MSCs. In vitro, RR-L containing serum promoted the osteogenic differentiation and suppressed adipogenic differentiation of MSCs via downregulation of the NF-κB signaling pathway. Also, RR-L containing serum inhibited the tumor necrosis factor-α (TNF-α) induced activation of the NF-κB signaling pathway. On the opposite, the addition of the NF-κB specific inhibitor significantly reduced the effect of RR-L on MSCs.

Conclusions

In the current study, network pharmacology prediction and experimental validation elucidated that the RR-L herb pair restored damaged MSC differentiation potential via the NF-κB signaling pathway; this could be the possible mechanism of RR-L in treating OP. This finding provides an alternative option in OP therapy.

Punicalagin Regulates Signaling Pathways in Inflammation-Associated Chronic Diseases

Inflammation is a complex biological defense system associated with a series of chronic diseases such as cancer, arthritis, diabetes, cardiovascular and neurodegenerative diseases. The extracts of pomegranate fruit and peel have been reported to possess health-beneficial properties in inflammation-associated chronic diseases. Punicalagin is considered to be the major active component of pomegranate extracts. In this review we have focused on recent studies into the therapeutic effects of punicalagin on inflammation-associated chronic diseases and the regulatory roles in NF-κB, MAPK, IL-6/JAK/STAT3 and PI3K/Akt/mTOR signaling pathways. We have concluded that punicalagin may be a promising therapeutic compound in preventing and treating inflammation-associated chronic diseases, although further clinical studies are required.

Exosome: Function and Application in Inflammatory Bone Diseases

In the skeletal system, inflammation is closely associated with many skeletal disorders, including periprosthetic osteolysis (bone loss around orthopedic implants), osteoporosis, and rheumatoid arthritis. These diseases, referred to as inflammatory bone diseases, are caused by various oxidative stress factors in the body, resulting in long-term chronic inflammatory processes and eventually causing disturbances in bone metabolism, increased osteoclast activity, and decreased osteoblast activity, thereby leading to osteolysis. Inflammatory bone diseases caused by nonbacterial factors include inflammation- and bone resorption-related processes. A growing number of studies show that exosomes play an essential role in developing and progressing inflammatory bone diseases. Mechanistically, exosomes are involved in the onset and progression of inflammatory bone disease and promote inflammatory osteolysis, but specific types of exosomes are also involved in inhibiting this process. Exosomal regulation of the NF-κB signaling pathway affects macrophage polarization and regulates inflammatory responses. The inflammatory response further causes alterations in cytokine and exosome secretion. These signals regulate osteoclast differentiation through the receptor activator of the nuclear factor-kappaB ligand pathway and affect osteoblast activity through the Wnt pathway and the transcription factor Runx2, thereby influencing bone metabolism. Overall, enhanced bone resorption dominates the overall mechanism, and over time, this imbalance leads to chronic osteolysis. Understanding the role of exosomes may provide new perspectives on their influence on bone metabolism in inflammatory bone diseases. At the same time, exosomes have a promising future in diagnosing and treating inflammatory bone disease due to their unique properties.

Identification of Potential Therapeutic Targets and Molecular Regulatory Mechanisms for Osteoporosis by Bioinformatics Methods

BACKGROUND

Osteoporosis is characterized by low bone mass, deterioration of bone tissue structure, and susceptibility to fracture. New and more suitable therapeutic targets need to be discovered.

METHODS

We collected osteoporosis-related datasets (GSE56815, GSE99624, and GSE63446). The methylation markers were obtained by differential analysis. Degree, DMNC, MCC, and MNC plug-ins were used to screen the important methylation markers in PPI network, then enrichment analysis was performed. ROC curve was used to evaluate the diagnostic effect of osteoporosis. In addition, we evaluated the difference in immune cell infiltration between osteoporotic patients and control by ssGSEA. Finally, differential miRNAs in osteoporosis were used to predict the regulators of key methylation markers.

RESULTS

A total of 2351 differentially expressed genes and 5246 differentially methylated positions were obtained between osteoporotic patients and controls. We identified 19 methylation markers by PPI network. They were mainly involved in biological functions and signaling pathways such as apoptosis and immune inflammation. HIST1H3G, MAP3K5, NOP2, OXA1L, and ZFPM2 with higher AUC values were considered key methylation markers. There were significant differences in immune cell infiltration between osteoporotic patients and controls, especially dendritic cells and natural killer cells. The correlation between MAP3K5 and immune cells was high, and its differential expression was also validated by other two datasets. In addition, NOP2 was predicted to be regulated by differentially expressed hsa-miR-3130-5p.

CONCLUSION

Our efforts aim to provide new methylation markers as therapeutic targets for osteoporosis to better treat osteoporosis in the future.

Nrf2 Signaling Pathway in Chemoprotection and Doxorubicin Resistance: Potential Application in Drug Discovery

Doxorubicin (DOX) is extensively applied in cancer therapy due to its efficacy in suppressing cancer progression and inducing apoptosis. After its discovery, this chemotherapeutic agent has been frequently used for cancer therapy, leading to chemoresistance. Due to dose-dependent toxicity, high concentrations of DOX cannot be administered to cancer patients. Therefore, experiments have been directed towards revealing underlying mechanisms responsible for DOX resistance and ameliorating its adverse effects. Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling is activated to increase levels of reactive oxygen species (ROS) in cells to protect them against oxidative stress. It has been reported that Nrf2 activation is associated with drug resistance. In cells exposed to DOX, stimulation of Nrf2 signaling protects cells against cell death. Various upstream mediators regulate Nrf2 in DOX resistance. Strategies, both pharmacological and genetic interventions, have been applied for reversing DOX resistance. However, Nrf2 induction is of importance for alleviating side effects of DOX. Pharmacological agents with naturally occurring compounds as the most common have been used for inducing Nrf2 signaling in DOX amelioration. Furthermore, signaling networks in which Nrf2 is a key player for protection against DOX adverse effects have been revealed and are discussed in the current review.

Chondroitin Sulfate Alleviates Diabetic Osteoporosis and Repairs Bone Microstructure via Anti-Oxidation, Anti-Inflammation, and Regulating Bone Metabolism

Diabetic osteoporosis (DOP) belongs to secondary osteoporosis caused by diabetes; it has the characteristics of high morbidity and high disability. In the present study, we constructed a type 1 diabetic rat model and administered chondroitin sulfate (200 mg/kg) for 10 weeks to observe the preventive effect of chondroitin sulfate on the bone loss of diabetic rats. The results showed that chondroitin sulfate can reduce blood glucose and relieve symptoms of diabetic rats; in addition, it can significantly increase the bone mineral density, improve bone microstructure, and reduce bone marrow adipocyte number in diabetic rats; after 10 weeks of chondroitin sulfate administration, the SOD activity level was upregulated, as well as CAT levels, indicating that chondroitin sulfate can alleviate oxidative stress in diabetic rats. Chondroitin sulfate was also found to reduce the level of serum inflammatory cytokines (TNF-α, IL-1, IL-6, and MCP-1) and alleviate the inflammation in diabetic rats; bone metabolism marker detection results showed that chondroitin sulfate can reduce bone turnover in diabetic rats (decreased RANKL, CTX-1, ALP, and TRACP 5b levels were observed after 10 weeks of chondroitin sulfate administration). At the same time, the bone OPG and RUNX 2 expression levels were higher after chondroitin sulfate treatment, the bone RANKL expression was lowered, and the OPG/RANKL ratio was upregulated. All of the above indicated that chondroitin sulfate could prevent STZ-induced DOP and repair bone microstructure; the main mechanism was through anti-oxidation, anti-inflammatory, and regulating bone metabolism. Chondroitin sulfate could be used to develop anti-DOP functional foods and diet interventions for diabetes.

The Role and Mechanism of Exosomes from Umbilical Cord Mesenchymal Stem Cells in Inducing Osteogenesis and Preventing Osteoporosis

Mesenchymal stem cell (MSC) exosomes promote tissue regeneration and repair, and thus might be used to treat many diseases; however, the influence of microenvironmental conditions on exosomes remains unclear. The present study aimed to analyze the effect of osteogenic induction on the functions of human umbilical cord MSC (HucMSC)-derived exosomes. Exosomes from standardized stem cell culture (Exo1) and osteogenic differentiation-exosomes (Exo2) were co-cultured with osteoblasts, separately. Cell counting kit-8 assays, alkaline phosphatase and alizarin red staining were used to observe the exosomes' effects on osteoblast proliferation and differentiation. The levels of osteogenic differentiation-related proteins were analyzed using western blotting. Estrogen-deficient osteoporosis model mice were established, and treated with the two exosome preparations. Micro-computed tomography and hematoxylin and eosin staining were performed after 6 weeks. MicroRNAs in Exo1 and Exo2 were sequenced and analyzed using bioinformatic analyses. Compared with Exo1 group, Exo2 had a stronger osteogenic differentiation promoting effect, but a weaker proliferation promoting effect. In ovariectomy-induced osteoporosis mice, both Exo1 and Exo2 improved the tibial density and reversed osteoporosis in vivo. High-throughput microRNA sequencing identified 221 differentially expressed microRNAs in HucMSC-derived exosomes upon osteogenic induction as compared with the untreated control group. Importantly, we found that 41 of these microRNAs are potentially critical for MSC-secreted exosomes during osteogenic induction. Mechanistically, exosomal miRNAs derived from osteogenic induced-HucMSCs are involved in bone development and differentiation, such as osteoclast differentiation and the MAPK signaling pathway. The expression of hsa-mir-2110 and hsa-mir-328-3p gradually increased with prolonged osteogenic differentiation and regulated target genes associated with bone differentiation, suggesting that they are probably the most important osteogenesis regulatory microRNAs in exosomes. In conclusion, we examined the contribution of osteogenic induction to the function of exosomes secreted by HucMSCs following osteogenic differentiation in vitro and in vivo, and reveal the underlying molecular mechanisms of exosome action during osteoporosis.

Punicalagin Exerts Protective Effects against Ankylosing Spondylitis by Regulating NF-κB-TH17/JAK2/STAT3 Signaling and Oxidative Stress

Background

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by sacroiliitis and spinal rigidity of the axial joints. The role of oxidative stress and increased proinflammatory cytokines is well documented in AS pathogenesis. Punicalagin (2,3-hexahydroxydiphenoyl-gallagyl-D-glucose), an ellagitannin widely present in pomegranates, is found to exhibit potent anti-inflammatory, antiproliferative, and antioxidative effects. The present study was undertaken to investigate the effects of punicalagin in a rodent model of AS.

Methods

BALB/c mice induced spondylitis were sacrificed 24 h after the last injection of proteoglycan extract. Histological scoring was done to assess the degree of the disease. The expression of JAK2/STAT3 proteins and proteins of the nuclear factor-κB (NF-κB) pathway was determined by immunoblotting. Serum levels of inflammatory mediators—TNF-α, IL-1β, IL-6, IL-17A, and IL-23—were assessed. Levels of lipid peroxidation and reactive oxygen species (ROS) were quantified. Antioxidant status as a measure of activities of antioxidant enzymes—catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD)—was determined.

Results

Punicalagin effectively improved antioxidant status and decreased lipid peroxidation, ROS production, and serum levels of inflammatory mediators. NF-κB pathway and JAK2/STAT3 signaling were significantly (p < 0.05) downregulated. Punicalagin effectively regulated the production of cytokines by the Th17 cells and the IL-17A/IL-23 axis.

Conclusion

The observations suggest that punicalagin exerts a protective role in AS via reducing oxidative stress and regulating NF-κB/TH17/JAK2/STAT3 signal. Punicalagin thus could be explored further as a potent candidate compound in the treatment of AS.

A Synthetic Peptide, CK2.3, Inhibits RANKL-Induced Osteoclastogenesis through BMPRIa and ERK Signaling Pathway

The skeletal system plays an important role in the development and maturation process. Through the bone remodeling process, 10% of the skeletal system is renewed every year. Osteoblasts and osteoclasts are two major bone cells that are involved in the development of the skeletal system, and their activity is kept in balance. An imbalance between their activities can lead to diseases such as osteoporosis that are characterized by significant bone loss due to the overactivity of bone-resorbing osteoclasts. Our laboratory has developed a novel peptide, CK2.3, which works as both an anabolic and anti-resorptive agent to induce bone formation and prevent bone loss. We previously reported that CK2.3 mediated mineralization and osteoblast development through the SMAD, ERK, and AKT signaling pathways. In this study, we demonstrated the mechanism by which CK2.3 inhibits osteoclast development. We showed that the inhibition of MEK by the U0126 inhibitor rescued the osteoclast development of RAW264.7 induced by RANKL in a co-culture system with CK2.3. We observed that CK2.3 induced ERK activation and BMPRIa expression on Day 1 after stimulation with CK2.3. While CK2.3 was previously reported to induce the SMAD signaling pathway in osteoblast development, we did not observe any changes in SMAD activation in osteoclast development with CK2.3 stimulation. Understanding the mechanism by which CK2.3 inhibits osteoclast development will allow CK2.3 to be developed as a new treatment for osteoporosis.