Trehalose reduces bone loss in experimental biliary cirrhosis rats via ERK phosphorylation regulation by enhancing autophagosome formation

Acteoside delays the fibrosis process of diabetic nephropathy by anti-oxidation and regulating the autophagy-lysosome pathway

Renal fibrosis is the final pathological change of kidney disease, it has also been recognized to be critical for the final progression of diabetic nephropathy (DN) to kidney failure. Acteoside (ACT) is a phenylethanoid glycoside widely distributed in dicotyledonous plants. It has many pharmacological activities, such as anti-oxidation, anti-inflammation, anti-cancer, neuroprotection, cardiovascular protection, anti-diabetes, bone and cartilage protection, liver and kidney protection, and antibacterial activity. This study aims to investigate the protective effects of ACT on renal interstitial fibrosis in rats with DN induced by intraperitoneal injection of streptozocin (STZ) combined with unilateral nephrectomy and its mechanism. In vivo and in vitro, the effects of ACT on reactive oxygen species (ROS) level, oxidative tubular injury, as well as damage of autophagic flux and lysosome in the DN model were detected. Results indicate that administration of ACT delayed the progression of renal interstitial fibrosis in DN by anti-oxidation and regulating the autophagy-lysosome pathway, which may potentially be attributed to the regulatory influence of ACT on transcription factor EB (TFEB).

Role of SIRT3 in bone homeostasis and its application in preventing and treating bone diseases

Bone homeostasis refers to the balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption and the maintenance of stable bone mass. SIRT3 is a class of mitochondrial protein deacetylase that influences various mitochondrial functions and is involved in the mechanisms underlying resistance to aging; regulation of bone marrow mesenchymal stem cells, osteoblasts, and osteoclasts; and development of osteoporosis, osteoarthritis, and other bone diseases. Moreover, exercise affects bones through SIRT3. Thus, studies on SIRT3 may provide insights for the treatment of bone diseases. Although SIRT3 can exert multiple effects on bone, the specific mechanism by which it regulates bone homeostasis remains unclear. By evaluating the relevant literature, this review discusses the structure and function of SIRT3, reveals the role and associated mechanisms of SIRT3 in regulating bone homeostasis and mediating bone health during exercise, and highlights the potential pharmacological value of SIRT3 in treating bone diseases.

Trehalose delays postmenopausal osteoporosis by enhancing AKT/TFEB pathway‑dependent autophagy flow in rats

Osteoporosis is a systemic bone metabolic disorder that plagues the health and quality of life of the elderly. Autophagy plays an important role in bone formation while maintaining the homeostasis of the body. Trehalose is a mTOR-independent autophagy inducer, but to the best of our knowledge, there is no rat model of postmenopausal osteoporosis. The present study found that trehalose can delay postmenopausal osteoporosis in rats, which may be achieved by inducing and enhancing AKT/transcription factor EB pathway-dependent autophagy flow. The specific mechanism of its occurrence needs to be further studied. Trehalose-containing drugs are promising for delaying postmenopausal osteoporosis. Hematoxylin and eosin (H&E) staining, western blotting, micro computerized tomography (CT) scanning and Transmission electron microscopy were used to investigate the role of trehalose in postmenopausal osteoporosis rat model at protein, cell and histology aspects. According to the H&E staining results, the bone trabecular histological structure of the trehalose group was superior to that of the model group. The Micro CT scanning indicated the imaging structure of bone trabeculae in the trehalose group was superior to than that in the model group. Western blotting indicated the activation of autophagic flow in trehalose group, the autophagy degree of the trehalose group is greater than that of the model group; Transmission electron microscopy indicated the autophagy degree of the Trehalose group was greater than that of the model group under electron microscopy. Trehalose can delay postmenopausal osteoporosis in rats, which may be achieved by inducing and enhancing Akt/TFEB pathway-dependent autophagy flow.

Metformin alleviates bone loss in ovariectomized mice through inhibition of autophagy of osteoclast precursors mediated by E2F1

Background

Postmenopausal bone loss, mainly caused by excessive bone resorption mediated by osteoclasts, has become a global public health burden. Metformin, a hypoglycemic drug, has been reported to have beneficial effects on maintaining bone health. However, the role and underlying mechanism of metformin in ovariectomized (OVX)-induced bone loss is still vague.

Results

In this study, we demonstrated for the first time that metformin administration alleviated bone loss in postmenopausal women and ovariectomized mice, based on reduced bone resorption markers, increased bone mineral density (BMD) and improvement of bone microstructure. Then, osteoclast precursors administered metformin in vitro and in vivo were collected to examine the differentiation potential and autophagical level. The mechanism was investigated by infection with lentivirus-mediated BNIP3 or E2F1 overexpression. We observed a dramatical inhibition of autophagosome synthesis and osteoclast formation and activity. Treatment with RAPA, an autophagy activator, abrogated the metformin-mediated autophagy downregulation and inhibition of osteoclastogenesis. Additionally, overexpression of E2F1 demonstrated that reduction of OVX-upregulated autophagy mediated by metformin was E2F1 dependent. Mechanistically, metformin-mediated downregulation of E2F1 in ovariectomized mice could downregulate BECN1 and BNIP3 levels, which subsequently perturbed the binding of BECN1 to BCL2. Furthermore, the disconnect between BECN1 and BCL2 was shown by BNIP3 overexpression.

Conclusion

In summary, we demonstrated the effect and underlying mechanism of metformin on OVX-induced bone loss, which could be, at least in part, ascribed to its role in downregulating autophagy during osteoclastogenesis via E2F1-dependent BECN1 and BCL2 downregulation, suggesting that metformin or E2F1 inhibitor is a potential agent against postmenopausal bone loss.

Heterozygous LRP1 deficiency causes developmental dysplasia of the hip by impairing triradiate chondrocytes differentiation due to inhibition of autophagy

Developmental dysplasia of the hip (DDH) is one of the most common congenital skeletal malformations; however, its etiology remains unclear. Here, we conducted whole-exome sequencing and identified likely pathogenic variants in the LRP1 (low-density lipoprotein receptor-related protein 1) gene in two families and seven unrelated patients. We found that the timing of triradiate cartilage development was brought forward 1 or 2 wk earlier in the LRP-deficient mice, which leads to malformation of the acetabulum and femoral head. Furthermore, Lrp1 deficiency caused a significant decrease of chondrogenic ability in vitro. Our study reveals a critical role of LRP1 in the etiology and pathogenesis of DDH, opening an avenue for its treatment.

Developmental dysplasia of the hip (DDH) is one of the most common congenital skeletal malformations; however, its etiology remains unclear. Here, we conducted whole-exome sequencing in eight DDH families followed by targeted sequencing of 68 sporadic DDH patients. We identified likely pathogenic variants in the LRP1 (low-density lipoprotein receptor-related protein 1) gene in two families and seven unrelated patients. All patients harboring the LRP1 variants presented a typical DDH phenotype. The heterozygous Lrp1 knockout (KO) mouse (Lrp1^+/−) showed phenotypes recapitulating the human DDH phenotypes, indicating Lrp1 loss of function causes DDH. Lrp1 knockin mice with a missense variant corresponding to a human variant identified in DDH (Lrp1^R1783W) also presented DDH phenotypes, which were milder in heterozygotes and severer in homozygotes than those of the Lrp1 KO mouse. The timing of triradiate cartilage development was brought forward 1 or 2 wk earlier in the LRP-deficient mice, which leads to malformation of the acetabulum and femoral head. Furthermore, Lrp1 deficiency caused a significant decrease of chondrogenic ability in vitro. During the chondrogenic induction of mice bone marrow stem cells and ATDC5 (an inducible chondrogenic cell line), Lrp1 deficiency caused decreased autophagy levels with significant β-catenin up-regulation and suppression of chondrocyte marker genes. The expression of chondrocyte markers was rescued by PNU-74654 (a β-catenin antagonist) in an shRNA-Lrp1–expressed ATDC5 cell. Our study reveals a critical role of LRP1 in the etiology and pathogenesis of DDH, opening an avenue for its treatment.

Trehalose improves palmitic acid-induced apoptosis of osteoblasts by regulating SIRT3-medicated autophagy via the AMPK/mTOR/ULK1 pathway

Accumulation of lipid substances decreased the activity of osteoblasts. Trehalose is a typical stress metabolite to form a protective membrane on cell surface which has been demonstrated to regulate lipid metabolism. This activity of Trehalose indicates the potential effect of osteoporosis treatment. Our study aimed to determine the therapeutic effect of Trehalose in high fat-induced osteoporosis. We used palmitic acid (PA) to mimic the state of high fat and observed the apoptosis ratio of osteoblasts increased. After adding Trehalose, the apoptosis ratio decreased obviously. Autophagy is a regulatory means involved in the process of apoptosis. We detected the autophagy protein and found that the expression of Beclin-1, Atg5, and LC3 II increased, and p62 decreased after Trehalose treatment. When adding an autophagy inhibitor (3-MA), the expression of Beclin-1, Atg5, and LC3 II decreased, and p62 increased. These results indicated autophagy was an important factor involved in the preventive effect of Trehalose in PA-induced apoptosis. SIRT3 is a mitochondrial gene that can inhibit apoptosis, which has been reported to promote autophagy. We used SIRT3-siRNA to silence the expression of SIRT3 and found the effect of Trehalose was counteracted. The apoptosis ratio increased and the expression of Beclin-1, Atg5, and LC3 II decreased, p62 increased. Additionally, we also fed the mice with a high-fat diet (HFD) and intragastrical Trehalose. The results showed that Trehalose could inhibit the bone mass loss with HFD. Our study revealed the effect and mechanism of Trehalose in the treatment of osteoporosis.

Gut Metabolite Urolithin A Inhibits Osteoclastogenesis and Senile Osteoporosis by Enhancing the Autophagy Capacity of Bone Marrow Macrophages

Senile osteoporosis (SOP) is a systemic bone disease that is significantly associated with age and eventually leads to deteriorated bone strength and increased fracture risk. Urolithin A (Uro-A) is a gut microbiome-derived compound that is mainly produced from pomegranates and some nuts. Uro-A has attracted great attention in recent years in view of its protective effects on aging-related diseases, including muscle dysfunction, kidney disease and knee injury. However, its protective influence and possible mechanisms in senile osteoporosis remain unclear. Our study describes the beneficial effect of Uro-A on bone marrow macrophages (BMMs). The in vitro results demonstrated that Uro-A inhibited receptor activator for nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis in BMMs in a concentration-dependent manner. Uro-A significantly reduced the expression of osteoclast-related genes and bone resorption. Mechanistically, we found that the autophagy ability of BMMs was significantly enhanced in the early stage of Uro-A treatment, accompanied by the activation of LC3 and Beclin 1. At the same time, this enhanced autophagy activity was maintained until the later stage after stimulation with RANKL. Furthermore, we found that the MARK signaling pathway was blocked by Uro-A treatment. In a mouse model of aging, Uro-A effectively inhibited bone loss in the proximal femur, spine and tibia of aging mice. These results indicated that Uro-A is a robust and effective treatment for preventing senile osteoporosis bone loss.

A sustained-release Trametinib bio-multifunction hydrogel inhibits orthodontically induced inflammatory root resorption

Orthodontic tooth movement (OTM) is a bone reconstruction process. In most cases, OTM could induce root resorption as a common side effect, called orthodontically induced inflammatory root resorption (OIIRR). OIIRR affects tooth health and interferes with the stability of orthodontic treatment. Osteoclasts, which perform bone resorption in OTM, attack cementum, causing OIIRR. Many signaling pathways are involved in the maturation and differentiation of osteoclasts, among which the ERK1/2 is one of the important pathways. In this experiment, we added Trametinib (Tra), a specific inhibitor of ERK1/2, to catechol-modified chitosan (CHI-C) and oxidized dextran (ODex) to form a CCOD-Trametinib composite hydrogel (CCOD-Tra) to prevent OIIRR. CCOD-Tra exhibited good biocompatibility, injectability, strong adhesion, good hemostatic function and sustained release of Tra. We performed local injection of CCOD-Tra into the periodontal tissues of rats. CCOD-Tra firmly adhered to the periodontal tissues and then released Tra to establish a good biological environment and maintain a drug concentration at a high level around the roots for a long time. H&E, TRAP, immunochemistry staining and micro-CT indicated that CCOD-Tra had a good effect in terms of preventing OIIRR. Cell experiments showed that CCOD-Tra reduced the expression of TRAP, MMP-9 and C-FOS in osteoclast cells through the ERK1/2 signaling pathway to inhibit the differentiation and maturation of osteoclasts. Based on the above results, we concluded that CCOD-Tra had the ability to prevent OIIRR, the high adhesion and injectability of CCOD may provide better therapeutic ideas for clinical prevention of OIIRR.

The effect of QiangGuYin on osteoporosis through the AKT/mTOR/autophagy signaling pathway mediated by CKIP-1

Osteoporosis is a systemic bone disease characterized by decreased bone mass and deterioration of bone microstructure, which leads to increased bone fragility and increased risk of fractures. Casein kinase 2 interacting protein 1 (CKIP-1, also known as PLEKHO1) is involved in the biological process of bone formation, differentiation and apoptosis, and is a negative regulator of bone formation. QiangGuYin (QGY) is a famous TCM formula that has been widely used in China for the clinical treatment of postmenopausal osteoporosis for decades, but the effect in regulating CKIP-1 on osteoporosis is not fully understood. This study aimed to explore the potential mechanism of CKIP-1 participating in autophagy in bone cells through the AKT/mTOR signaling pathway and the regulatory effect of QGY. The results in vivo showed that QGY treatment can significantly improve the bone quality of osteoporotic rats, down-regulate the expression of CKIP-1, LC3II/I and RANKL, and up-regulated the expression of p62, p-AKT/AKT, p-mTOR/mTOR, RUNX2 and OPG. It is worth noting that the results in vitro confirmed that CKIP-1 interacts with AKT. By up-regulating the expression of Atg5 and down-regulating the p62, the level of LC3 (autophagosome) is increased, and the cells osteogenesis and differentiation are inhibited. QGY inhibits the combination of CKIP-1 and AKT in osteoblasts, activates the AKT/mTOR signaling pathway, inhibits autophagy, and promotes cell differentiation, thereby exerting an anti-osteoporosis effect. Therefore, QGY targeting CKIP-1 to regulate the AKT/mTOR-autophagy signaling pathway may represent a promising drug candidate for the treatment of osteoporosis.

Bone healing around titanium implants in a preclinical model of bile duct ligation-induced liver injury

Objectives

Chronic liver disease increases the risk for periodontal disease and osteoporotic fractures, but its impacts on bone regeneration remain unknown. Herein, we studied the impact of liver cirrhosis on peri‐implant bone formation.

Material and Methods

A total of 20 male Wistar rats were randomly divided into two groups: one with the common bile duct ligated (BDL) and the respective sham‐treated control group (SHAM). After four weeks of disease induction, titanium mini‐screws were inserted into the tibia. Successful induction of liver cirrhosis was confirmed by the presence of clinical symptoms. Another four weeks later, peri‐implant bone volume per tissue volume (BV/TV) and bone‐to‐implant contact (BIC) were determined by histomorphometric analysis.

Results

Peri‐implant bone formation was not significantly different between the SHAM and BDL groups. In the cortical compartment, the median percentage of peri‐implant new bone was 10.1% (95% CI of mean 4.0–35.7) and 22.5% (13.8–30.6) in the SHAM and BDL groups, respectively (p = .26). Consistently, the new bone in direct contact with the implant was 18.1% (0.4–37.8) and 23.3% (9.2–32.8) in SHAM and BDL groups, respectively (p = .38). When measuring the medullary compartment, the new bone area was 7.1% (4.8–10.4) and 10.4% (7.2–13.5) in the SHAM and BDL groups, respectively (p = .17). Medullary new bone in direct contact with the implant was 10.0% (1.2–50.4) and 20.6% (16.8–35.3) in SHAM and BDL groups, respectively, and thus comparable between the two groups (p = .46).

Conclusions

Bile duct ligation has no significant impact on the early stages of peri‐implant bone formation.

The Role of IL-35 in the Pathophysiological Processes of Liver Disease

It is known that liver diseases have several characteristics of massive lipid accumulation and lipid metabolic disorder, and are divided into liver inflammation, liver fibrosis, liver cirrhosis (LC), and hepatocellular carcinoma (HCC) in patients. Interleukin (IL)-35, a new-discovered cytokine, can protect the liver from the environmental attack by increasing the ratio of Tregs (T regulatory cells) which can increase the anti-inflammatory cytokines and inhibit the proliferation of immune cellular. Interestingly, two opposite mechanisms (pro-inflammatory and anti-inflammatory) have connection with the ultimate formation of liver diseases, which suggest that IL-35 may play crucial function in the process of liver diseases through immunosuppressive regulation. Besides, some obvious advantages also imply that IL-35 can be considered as a new therapeutic target to control the progression of liver diseases, while its mechanism of function still needs further research.

Model Parameterization with Quantitative Proteomics: Case Study with Trehalose Metabolism in Saccharomyces cerevisiae

When Saccharomyces cerevisiae undergoes heat stress it stimulates several changes that are necessary for its survival, notably in carbon metabolism. Notable changes include increase in trehalose production and glycolytic flux. The increase in glycolytic flux has been postulated to be due to the regulatory effects in upper glycolysis, but this has not been confirmed. Additionally, trehalose is a useful industrial compound for its protective properties. A model of trehalose metabolism in S. cerevisiae was constructed using Convenient Modeller, a software that uses a combination of convenience kinetics and a genetic algorithm. The model was parameterized with quantitative omics under standard conditions and validated using data collected under heat stress conditions. The completed model was used to show that feedforward activation of pyruvate kinase by fructose 1,6-bisphosphate during heat stress contributes to the increase in metabolic flux. We were also able to demonstrate in silico that overexpression of enzymes involved in production and degradation of trehalose can lead to higher trehalose yield in the cell. By integrating quantitative proteomics with metabolic modelling, we were able to confirm that the flux increase in trehalose metabolic pathways during heat stress is due to regulatory effects and not purely changes in enzyme expression. The overexpression of enzymes involved in trehalose metabolism is a potential approach to be exploited for trehalose production without need for increasing temperature.

Tumour dormancy in inflammatory microenvironment: A promising therapeutic strategy for cancer-related bone metastasis

Cancer metastasis is a unique feature of malignant tumours. Even bone can become a common colonization site due to the tendency of solid tumours, including breast cancer (BCa) and prostate cancer (PCa), to metastasize to bone. Currently, a previous concept in tumour metabolism called tumour dormancy may be a promising target for antitumour treatment. When disseminated tumour cells (DTCs) metastasize to the bone microenvironment, they form a flexible regulatory network called the "bone-tumour-inflammation network". In this network, bone turnover as well as metabolism, tumour progression, angiogenesis and inflammatory responses are highly unified and coordinated, and a slight shift in this balance can result in the disruption of the microenvironment, uncontrolled inflammatory responses and excessive tumour growth. The purpose of this review is to highlight the regulatory effect of the "bone-tumour-inflammation network" in tumour dormancy. Osteoblast-secreted factors, bone turnover and macrophages are emphasized and occupy in the main part of the review. In addition, the prospective clinical application of tumour dormancy is also discussed, which shows the direction of future research.

Autophagy was involved in tumor necrosis factor-α-inhibited osteogenic differentiation of murine calvarial osteoblasts through Wnt/β-catenin pathway

Periodontitis is an inflammatory disease with a high incidence characterized by irreversible destruction of alveolar bone. This study aimed to investigate the effect of tumor necrosis factor-α (TNF-α) on osteogenic differentiation and its molecular mechanism. TNF-α inhibited osteogenic differentiation as revealed by the lower accumulation of osteoblastic genes like runt-related transcription factor (Runx2), alkaline phosphatase (ALP), osteoprotegerin (OPG), and osteocalcin (OCN). Moreover, TNF-α down-regulated the expressions of LC3II, ATG7, and beclin 1 (BECN1); suggesting that autophagy was inhibited during the process of osteogenic differentiation. Consistently, Wnt/β-catenin signaling pathway members such as low-density lipoprotein receptor-related protein 5 (LRP5), β-catenin, and phosphorylated-β-catenin (p-β-catenin) were reduced by TNF-α. Furthermore, the inhibitory effect of TNF-α on osteogenic differentiation and the Wnt/β-catenin signaling pathway could be abated by autophagy inducers but exacerbated by autophagy inhibitors. The most intriguing finding of all was that TNF-α inhibited osteoblastic differentiation and the Wnt/β-catenin signaling pathway by down-regulating autophagy, and autophagy positively regulated the Wnt/β-catenin pathway and thus influenced osteoblastic differentiation. Our study provides a theoretical basis for autophagy-inducer therapy for the alveolar bone loss caused by periodontitis.