ANGPTL2 deletion inhibits osteoclast generation by modulating NF-κB/MAPKs/Cyclin pathways

Bone marrow mesenchymal stem cells derived exosomal miRNAs can modulate diabetic bone-fat imbalance

Background

Diabetes mellitus is a chronic metabolic disease with systemic complications. Patient with diabetes have increased risks of bone fracture. Previous studies report that diabetes could affect bone metabolism, however, the underlying mechanism is still unclear.

Methods

We isolated exosomes secreted by bone marrow mesenchymal stem cells of normal and diabetic mice and test their effects on osteogenesis and adipogenesis. Then we screened the differential microRNAs by high-throughput sequencing and explored the function of key microRNA in vitro and in vivo.

Results

We find that lower bone mass and higher marrow fat accumulation, also called bone-fat imbalance, exists in diabetic mouse model. Exosomes secreted by normal bone marrow mesenchymal stem cells (BMSCs-Exos) enhanced osteogenesis and suppressed adipogenesis, while these effects were diminished in diabetic BMSCs-Exos. miR-221, as one of the highly expressed miRNAs within diabetic BMSCs-Exos, showed abilities of suppressing osteogenesis and promoting adipogenesis both in vitro and in vivo. Elevation of miR-221 level in normal BMSCs-Exos impairs the ability of regulating osteogenesis and adipogenesis. Intriguingly, using the aptamer delivery system, delivery normal BMSCs-Exos specifically to BMSCs increased bone mass, reduced marrow fat accumulation, and promoted bone regeneration in diabetic mice.

Conclusion

We demonstrate that BMSCs derived exosomal miR-221 is a key regulator of diabetic osteoporosis, which may represent a potential therapeutic target for diabetes-related skeletal disorders.

ANGPTL2 Deletion Attenuates Neuroinflammation and Cognitive Dysfunction Induced by Isoflurane in Aged Mice through Modulating MAPK Pathway

Postoperative cognitive dysfunction (POCD) is a well-known complication after surgery with cognitive impairments. Angiopoietin-like protein 2 (ANGPTL2) has been found to be associated with inflammation. However, the role of ANGPTL2 in inflammation of POCD is unclear. Here, mice were subjected into isoflurane anesthesia. It was demonstrated that isoflurane increased ANGPTL2 expression and promoted pathological change in brain tissues. However, downregulation of ANGPTL2 alleviated the pathological change and elevated learning and memory abilities, improving isoflurane-induced cognitive dysfunction in mice. In addition, isoflurane-induced cell apoptosis and inflammation were repressed via ANGPTL2 knockdown in mice. Downregulation of ANGPTL2 was also verified to suppress isoflurane-induced microglial activation, evidenced by a decrease of Iba1 and CD86 expressions and an increase of CD206 expression. Further, the isoflurane-induced MAPK signaling pathway was repressed through downregulation of ANGPTL2 in mice. In conclusion, this study proved that downregulation of ANGPTL2 attenuated isoflurane-induced neuroinflammation and cognitive dysfunction in mice via modulating the MAPK pathway, which provided a new therapeutic target for POCD.

Clinical, biochemical and genetic characteristics of MOGS-CDG: a rare congenital disorder of glycosylation

PURPOSE

To summarise the clinical, molecular and biochemical phenotype of mannosyl-oligosaccharide glucosidase-related congenital disorders of glycosylation (MOGS-CDG), which presents with variable clinical manifestations, and to analyse which clinical biochemical assay consistently supports diagnosis in individuals with bi-allelic variants in MOGS.

METHODS

Phenotypic characterisation was performed through an international and multicentre collaboration. Genetic testing was done by exome sequencing and targeted arrays. Biochemical assays on serum and urine were performed to delineate the biochemical signature of MOGS-CDG.

RESULTS

Clinical phenotyping revealed heterogeneity in MOGS-CDG, including neurological, immunological and skeletal phenotypes. Bi-allelic variants in MOGS were identified in 12 individuals from 11 families. The severity in each organ system was variable, without definite genotype correlation. Urine oligosaccharide analysis was consistently abnormal for all affected probands, whereas other biochemical analyses such as serum transferrin analysis was not consistently abnormal.

CONCLUSION

The clinical phenotype of MOGS-CDG includes multisystemic involvement with variable severity. Molecular analysis, combined with biochemical testing, is important for diagnosis. In MOGS-CDG, urine oligosaccharide analysis via matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry can be used as a reliable biochemical test for screening and confirmation of disease.

Tumor-derived miR-378a-3p-containing extracellular vesicles promote osteolysis by activating the Dyrk1a/Nfatc1/Angptl2 axis for bone metastasis

Most prostate cancer (PCa)-related deaths are caused by progression to bone metastasis. Recently, the importance of extracellular vesicles (EVs) in pre-metastatic niche formation has been reported. However, whether and how tumor-derived EVs interact with bone marrow macrophages (BMMs) to release EV-delivered microRNAs to promote osteolysis and induce pre-metastatic niche formation for PCa bone metastasis remain unclear. Our in vitro and in vivo functional and mechanistic assays revealed that EV-mediated release of miR-378a-3p from tumor cells was upregulated in bone-metastatic PCa, maintaining low intracellular miR-378a-3p concentration to promote proliferation and MAOA-mediated epithelial-to-mesenchymal transition. Moreover, miR-378a-3p enrichment in tumor-derived EVs was induced by hnRNPA2B1 (a transfer chaperone) overexpression. After tumor-derived EVs were taken in by BMMs, enriched miR-378a-3p promoted osteolytic progression by inhibiting Dyrk1a to improve Nfatc1 (an osteolysis-related transcription factor) nuclear translocation, to activate the expression of downstream target gene Angptl2. As a feedback, increased Angptl2 secretion into the tumor environment promoted PCa progression. In conclusion, tumor-derived miR-378a-3p-containing EVs play a significant role in PCa bone metastasis by activating the Dyrk1a/Nfatc1/Angptl2 axis in BMMs to induce osteolytic progression, making miR-378a-3p a potential predictor of metastatic PCa. Reducing the release of miR-378a-3p-containing EVs or inhibiting the recruitment of miR-378a-3p into EVs can be a therapeutic strategy against PCa metastasis.

Osteopontin, a bridge links osteoarthritis and osteoporosis

Osteoarthritis (OA) is the most prevalent joint disease characterized by degradation of articular cartilage, inflammation, and changes in periarticular and subchondral bone of joints. Osteoporosis (OP) is another systemic skeletal disease characterized by low bone mass and bone mineral density (BMD) accompanied by microarchitectural deterioration in bone tissue and increased bone fragility and fracture risk. Both OA and OP are mainly affected on the elderly people. Recent studies have shown that osteopontin (OPN) plays a vital role in bone metabolism and homeostasis. OPN involves these biological activities through participating in the proliferation, migration, differentiation, and adhesion of several bone-related cells, including chondrocytes, synoviocytes, osteoclasts, osteoblasts, and marrow mesenchymal stem cells (MSCs). OPN has been demonstrated to be closely related to the occurrence and development of many bone-related diseases, such as OA and OP. This review summarizes the role of OPN in regulating inflammation activity and bone metabolism in OA and OP. Furthermore, some drugs that targeted OPN to treat OA and OP are also summarized in the review. However, the complex mechanism of OPN in regulating OA and OP is not fully elucidated, which drives us to explore the depth effect of OPN on these two bone diseases.

Angiopoietin-like protein 2 deficiency promotes periodontal inflammation and alveolar bone loss

BACKGROUND

Human periodontitis is a highly prevalent inflammatory disease that leads to connective tissue degradation, alveolar bone resorption, and tooth loss. Angiopoietin-like 2 (ANGPTL2) regulates chronic inflammation in various diseases and is functionally involved in maintaining tissue homeostasis and promoting tissue regeneration, but there is limited information about its function in periodontitis. Here we investigated the expression and explicit role of ANGPTL2 in periodontitis.

METHODS

Immunohistochemistry and quantitative real-time PCR (qRT-PCR) were used to detect the ANGPTL2 expression in periodontal tissues and periodontal ligament cells (PDLCs). A ligature-induced periodontitis model was generated in wild-type and ANGPTL2 knockout mice. qRT-PCR and enzyme-linked immunosorbent assay were used to assess the production of inflammatory cytokines and matrix metalloproteinases (MMPs) in cultured PDLCs. Western blot was performed to detect proteins in relevant signaling pathways.

RESULTS

Increased ANGPTL2 expression was observed in inflamed periodontal tissues and PDLCs. ANGPTL2 deficiency promoted alveolar bone loss with enhanced osteoclastogenesis and inflammatory reactions in ligature-induced periodontitis. Downregulation of ANGPTL2 remarkably enhanced expression levels of interleukin (IL)-6, IL-8, MMP1, and MMP13 in Porphyromonas gingivalis lipopolysaccharide-induced PDLCs, whereas ANGPTL2-overexpressing PDLCs showed opposite trends. ANGPTL2 downregulation activated STAT3 and nuclear factor-κB pathways and blocked Akt signaling under inflammatory environment. Treatment with a STAT3 inhibitor partially suppressed the inflammatory reaction of PDLCs mediated by ANGPTL2 knockdown.

CONCLUSIONS

Our study provides the first evidence of an anti-inflammatory effect of ANGPTL2 in murine periodontitis. The findings demonstrate the critical and protective role of ANGPTL2 in alveolar bone loss and periodontal inflammation.

Isoflavone-enriched soybean leaves attenuate ovariectomy-induced osteoporosis in rats by anti-inflammatory activity

BACKGROUND

With an increasing aging population, postmenopausal osteoporosis has become a global public health problem. Previous evidence has shown that postmenopausal osteoporosis is a skeletal disease mainly caused by estrogen deficiency, generally accompanied by inflammation, and dietary isoflavones may ameliorate postmenopausal osteoporosis by anti-inflammatory activity. We have generated isoflavone-enriched soybean leaves (IESLs), but their anti-inflammatory activity and effect on attenuating osteoporosis are still obscure. Here, we determined the isoflavone profiles of IESLs and evaluated their anti-inflammatory activity in lipopolysaccharide-stimulated RAW 264.7 cells and anti-osteoporotic effects on ovariectomy-induced osteoporosis in rats.

RESULTS

IESLs had a high content of total isoflavone. Hydrolysate of IESLs (HIESLs) was rich with the aglycones daidzein and genistein, and HIESLs can significantly inhibit lipopolysaccharide-induced inflammation by reducing messenger RNA expression of iNOS, COX-2, IL6, and IL1β. Moreover, ovariectomized rats receiving aqueous extracts of IESLs (HIESLs) orally maintained more bone mass than control rats did, which was attributed to inhibition of osteoclastogenesis by downregulating the messenger RNA expression of the bone-specific genes RANKL/OPG, OC, and cathepsin K, and the inflammation-related genes IL6, NFκB, and COX-2.

CONCLUSION

IESLs may attenuate postmenopausal osteoporosis by suppressing osteoclastogenesis with anti-inflammatory activity and be a potential source of functional food ingredients for the prevention of osteoporosis. © 2020 Society of Chemical Industry.

Bone Marrow Adipocytes, Adipocytokines, and Breast Cancer Cells: Novel Implications in Bone Metastasis of Breast Cancer

Accumulating discoveries highlight the importance of interaction between marrow stromal cells and cancer cells for bone metastasis. Bone is the most common metastatic site of breast cancer and bone marrow adipocytes (BMAs) are the most abundant component of the bone marrow microenvironment. BMAs are unique in their origin and location, and recently they are found to serve as an endocrine organ that secretes adipokines, cytokines, chemokines, and growth factors. It is reasonable to speculate that BMAs contribute to the modification of bone metastatic microenvironment and affecting metastatic breast cancer cells in the bone marrow. Indeed, BMAs may participate in bone metastasis of breast cancer through regulation of recruitment, invasion, survival, colonization, proliferation, angiogenesis, and immune modulation by their production of various adipocytokines. In this review, we provide an overview of research progress, focusing on adipocytokines secreted by BMAs and their potential roles for bone metastasis of breast cancer, and investigating the mechanisms mediating the interaction between BMAs and metastatic breast cancer cells. Based on current findings, BMAs may function as a pivotal modulator of bone metastasis of breast cancer, therefore targeting BMAs combined with conventional treatment programs might present a promising therapeutic option.

A landscape of circulating long non-coding RNA (lncRNA) expression profile and the predictive value of candidate lncRNAs for disease risk of knee osteoarthritis

Background

This study aimed to investigate the plasma long non‐coding RNA (lncRNA) expression profile in knee osteoarthritis (KOA) patients and the value of candidate lncRNAs for predicting KOA risk.

Methods

Plasma was obtained for RNA sequencing (RNA‐seq) in eight KOA patients and eight healthy controls (Ctrls). Ten candidate lncRNAs were then selected from the differentially expressed (DE) lncRNAs according to the rank of absolute value of Log₂ (fold change). Afterward, RT‐qPCR was used to examine 10 candidate lncRNAs expressions in plasma of 100 KOA patients and 100 Ctrls.

Results

In eight KOA patients and eight Ctrls, principal component analysis and heatmap plots disclosed that lncRNA and mRNA expression profile could distinguish KOA patients from Ctrls. Then Volcano plot identified 418 upregulated lncRNAs, 347 downregulated lncRNAs, 521 upregulated mRNAs, and 333 downregulated mRNAs in KOA patients compared to Ctrls. Next, enrichment analyses revealed that DE lncRNAs were mainly enriched in biological processes, molecular functions, and signaling pathways related to inflammation and bone formation. In 100 KOA patients and 100 Ctrls, eight candidate lncRNAs were dysregulated in KOA patients compared to Ctrls, including lncRNA ABCF2P2, lncRNA RP13‐16H11.7, lncRNA CTC‐340A15.2, lncRNA RP4‐735C1.6, lncRNA RP11‐293G6‐B.8, lncRNA RP11‐1246C19.1, lncRNA RP11‐303E16.6, and lncRNA RP5‐882C2.2. Receiver operating characteristic curve analysis revealed that these eight candidate lncRNAs presented with values for predicting KOA risk. Furthermore, multivariate logistic regression elucidated that six candidate lncRNAs could independently predict KOA risk.

Conclusion

We disclosed a landscape of circulating lncRNA expression profile in KOA patients, and discovered several specific lncRNAs which could assist in KOA management.

Establishment and Characteristic Analysis of a Dog Model for Autologous Homologous Cranioplasty

Objective

The aim of this study is to establish a large animal (dog) model that can be referred clinically for autologous homologous cranioplasty.

Methods

Our large skull defect dog model was established by emulating the decompressive craniectomy with 22 adult beagle dogs. The autologous bones were taken out from the dogs and divided into two groups, the freeze-drying (FD) group and the single freezing (SF) group. They were then stored in the bone bank at -20°C after being irradiated with 25 KGy. Three months later, the bones were reimplanted. After operation, we closely watch the experimental objects for four more months examining the infection and survival of the bone graft.

Results

Through macroscopic observation, it was found that, among 44 cranial flaps (bilateral) from the rest of the 22 dogs, grade A cranial flaps accounted for 86.4% (19/22) in the SF group and only 31.8% (7/22) in the FD group. Although osteogenic osteoclast, Harvard tube, neovascularization, and angiogenic factors were found through the pathological results, including an electron microscope and calmodulin tracer, it could be verified by using X-CT and micro-CT that early bone resorption could be still found even in grade A bone flap.

Conclusion

By using the common clinical method to preserve the cranial flaps, we established an experimental dog model of autologous cranioplasty for a large area of cranial defect. It was proved that this model could reproduce the infections and bone resorption which typically happened in clinical autologous homologous cranioplasty. As a conclusion, the established model can be used as an effective experimental tool for further research to improve the success rate of autologous homologous cranioplasty.

Effect of ANGPTL7 on Proliferation and Differentiation of MC3T3-E1 Cells

BACKGROUND Angiopoietin-like proteins (ANGPTL) are a family of secretory glycoproteins that are involved in many pathophysiological processes. ANGPTL7 is a newly-discovered member of the ANGPTL family and plays a role in corneal morphogenesis, angiogenesis, glaucoma, and cancer. To date, whether ANGPTL7 is involved in osteoporosis is unknown. Therefore, to discover the effects of ANGPTL7 on osteoporosis, we explored the expression of ANGPTL7 in preosteoblasts and assessed the mechanism underlying its effects on proliferation and differentiation abilities of preosteoblasts. MATERIAL AND METHODS Mouse MC3T3-E1 cells were cultured in osteogenic medium for osteogenic differentiation. The expression levels of ANGPTL7 were detected by RT-qPCR and Western blot assays. Moreover, the overexpressed plasmid of ANGPTL7 pMSCV-ANGPTL7 was transfected into MC3T3-E1 cells. CCK-8 was used to evaluate cell proliferation. ALP activity detection and alizarin red staining were performed to measure the effect of ANGPTL7 on osteogenic differentiation. The expression levels bone morphogenetic proteins (BMPs) and osteogenic markers ALP, runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and collagen I (Col I) were analyzed by Western blot. RESULTS When MC3T3-E1 cells were exposed to osteogenic medium, there was a significant increase in ANGPTL7, and overexpression of ANGPTL7 markedly promoted cell proliferation, ALP activity, and mineralization. Moreover, ANGPTL7 upregulated the levels of BMPs, especially BMP2/7, and the osteogenic markers ALP, Runx2, OCN, and Col I. CONCLUSIONS The results suggest that by regulating the expression of BMPs, ANGPTL7 directly promotes proliferation, differentiation, and mineralization of osteoblasts.

Mfn2 inhibits proliferation and cell-cycle in Hela cells via Ras-NF-κB signal pathway

Background

Mitofusin 2 (Mfn2) is outer membrane protein, as the inhibitor of Ras protein. This study aimed to investigate the effect of Mfn2 on cell proliferation, and cell-cycle in Hela cervical carcinoma cell lines.

Methods

After treated with Adv-mfn2 or Adv-control for 48 h and 60 h, the RNA and protein of Mfn2 in Hela cells were detected by qRT-PCR and western blot. The immunofluorescence assay was performed to observe the expression and sub-location of Mfn2 in Hela cells. The flow cytometry was performed to detect the cell cycle of Hela cells, while western blots were performed to observe the Ras-NF-κB signal pathway. Then, the xenografted cervix carcinoma mouse model was used to confirm the effect of Mfn2 in Hela cells in vivo and the expression of Ras-NF-κB signaling pathway in vivo.

Results

In immunofluorescence detection, Mfn2 was located in cytoplasmic, not in the nucleus. In addition, Mfn2 inhibited cell proliferation of Hela cells through reducing PCNA protein expression. Mfn2 induced arrest in G0/G1 phase of the cell cycle in Hela cells. Meanwhile, Mfn2 reduced Cyclin D1 protein expression. Moreover, Mfn2 decreased the Ras signal pathway proteins such as Myc, NF-κB p65, STAT3 in a dose-dependent manner. Then, the in vivo experiment also confirmed that Mfn2 could inhibit the tumor growth, and depress the Cyclin D1, Ras, Myc, NF-κB p65, Erk1/2 and mTOR protein expression.

Conclusions

Mfn2 could significantly inhibit cell proliferation in Hela cells. It might be acted as an potential anti-cancer target through inducing cell cycle arrest in human cervical carcinoma cells.

PC-3-Derived Exosomes Inhibit Osteoclast Differentiation by Downregulating miR-214 and Blocking NF-κB Signaling Pathway

Prostate cancer is a serious disease that can invade bone tissues. These bone metastases can greatly decrease a patient's quality of life, pose a financial burden, and even result in death. In recent years, tumor cell-secreted microvesicles have been identified and proposed to be a key factor in cell interaction. However, the impact of cancer-derived exosomes on bone cells remains unclear. Herein, we isolated exosomes from prostate cancer cell line PC-3 and investigated their effects on human osteoclast differentiation by tartrate-resistant acid phosphatase (TRAP) staining. The potential mechanism was evaluated by qRT-PCR, western blotting, and microRNA transfection experiments. The results showed that PC-3-derived exosomes dramatically inhibited osteoclast differentiation. Marker genes of mature osteoclasts, including CTSK, NFATc1, ACP5, and miR-214, were all downregulated in the presence of PC-3 exosomes. Furthermore, transfection experiments showed that miR-214 downregulation severely impaired osteoclast differentiation, whereas overexpression of miR-214 promoted differentiation. Furthermore, we demonstrated that PC-3-derived exosomes block the NF-κB signaling pathway. Our study suggested that PC-3-derived exosomes inhibit osteoclast differentiation by downregulating miR-214 and blocking the NF-κB signaling pathway. Therefore, elevating miR-214 levels in the bone metastatic site may attenuate the invasion of prostate cancer.