Angiotensin II induces mitochondrial oxidative stress and mtDNA damage in osteoblasts by inhibiting SIRT1–FoxO3a–MnSOD pathway

The Roles of Forkhead Box O3a (FOXO3a) in Bone and Cartilage Diseases - A Narrative Review

Bone and cartilage diseases are significantly associated with musculoskeletal disability. However, no effective drugs are available to cure them. FOXO3a, a member of the FOXO family, has been implicated in cell proliferation, ROS detoxification, autophagy, and apoptosis. The biological functions of FOXO3a can be modulated by post-translational modifications (PTMs), such as phosphorylation and acetylation. Several signaling pathways, such as MAPK, NF-κB, PI3K/AKT, and AMPK/Sirt1 pathways, have been implicated in the development of bone and cartilage diseases by mediating the expression of FOXO3a. In particular, FOXO3a acts as a transcriptional factor in mediating the expression of various genes, such as MnSOD, CAT, BIM, BBC3, and CDK6. FOXO3a plays a critical role in the metabolism of bone and cartilage. In this article, we mainly discussed the biological functions of FOXO3a in bone and cartilage diseases, such as osteoporosis (OP), osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis (AS), and intervertebral disc degeneration (IDD). FOXO3a can promote osteogenic differentiation, induce osteoblast proliferation, inhibit osteoclast activity, suppress chondrocyte apoptosis, and reduce inflammatory responses. Collectively, up-regulation of FOXO3a expression shows beneficial effects, and FOXO3a has become a potential target for bone and cartilage diseases.

Interruption of mitochondrial symbiosis is associated with the development of osteoporosis

Mitochondria maintain bacterial traits because of their endosymbiotic origins, yet the host cell recognizes them as non-threatening since the organelles are compartmentalized. Nevertheless, the controlled release of mitochondrial components into the cytoplasm can initiate cell death, activate innate immunity, and provoke inflammation. This selective interruption of endosymbiosis as early as 2 billion years ago allowed mitochondria to become intracellular signaling hubs. Recent studies have found that the interruption of mitochondrial symbiosis may be closely related to the occurrence of various diseases, especially osteoporosis (OP). OP is a systemic bone disease characterized by reduced bone mass, impaired bone microstructure, elevated bone fragility, and susceptibility to fracture. The interruption of intra-mitochondrial symbiosis affects the energy metabolism of bone cells, leads to the imbalance of bone formation and bone absorption, and promotes the occurrence of osteoporosis. In this paper, we reviewed the mechanism of mitochondrial intersymbiosis interruption in OP, discussed the relationship between mitochondrial intersymbiosis interruption and bone marrow mesenchymal stem cells, osteoblasts and osteoclasts, as well as the inheritance and adaptation in the evolutionary process, and prospected the future research direction to provide new ideas for clinical treatment.

Angiotensin II Alters Mitochondrial Membrane Potential and Lipid Metabolism in Rat Colonic Epithelial Cells

An over-active renin-angiotensin system (RAS) is characterized by elevated angiotensin II (Ang II). While Ang II can promote metabolic and mitochondrial dysfunction in tissues, little is known about its role in the gastrointestinal system (GI). Here, we treated rat primary colonic epithelial cells with Ang II (1-5000 nM) to better define their role in the GI. We hypothesized that Ang II would negatively affect mitochondrial bioenergetics as these organelles express Ang II receptors. Ang II increased cellular ATP production but reduced the mitochondrial membrane potential (MMP) of colonocytes. However, cells maintained mitochondrial oxidative phosphorylation and glycolysis with treatment, reflecting metabolic compensation with impaired MMP. To determine whether lipid dysregulation was evident, untargeted lipidomics were conducted. A total of 1949 lipids were detected in colonocytes spanning 55 distinct (sub)classes. Ang II (1 nM) altered the abundance of some sphingosines [So(d16:1)], ceramides [Cer-AP(t18:0/24:0)], and phosphatidylcholines [OxPC(16:0_20:5(2O)], while 100 nM Ang II altered some triglycerides and phosphatidylserines [PS(19:0_22:1). Ang II did not alter the relative expression of several enzymes in lipid metabolism; however, the expression of pyruvate dehydrogenase kinase 2 (PDK2) was increased, and PDK2 can be protective against dyslipidemia. This study is the first to investigate the role of Ang II in colonic epithelial cell metabolism.

Novel insights into the role of ubiquitination in osteoarthritis

Ubiquitination (Ub) and deubiquitination are crucial post-translational modifications (PTMs) that precisely regulate protein degradation. Under the catalysis of a cascade of E1-E2-E3 ubiquitin enzymes, ubiquitination extensively regulates protein degradation exerting direct impact on various cellular processes, while deubiquitination opposes the effect of ubiquitination and prevents proteins from degradation. Notably, such dynamic modifications have been widely investigated to be implicated in cell cycle, transcriptional regulation, apoptosis and so on. Therefore, dysregulation of ubiquitination and deubiquitination could lead to certain diseases through abnormal protein accumulation and clearance. Increasing researches have revealed that the dysregulation of catalytic regulators of ubiquitination and deubiquitination triggers imbalance of cartilage homeostasis that promotes osteoarthritis (OA) progression. Hence, it is now believed that targeting on Ub enzymes and deubiquitinating enzymes (DUBs) would provide potential therapeutic pathways. In the following sections, we will summarize the biological role of Ub enzymes and DUBs in the development and progression of OA by focusing on the updating researches, with the aim of deepening our understanding of the underlying molecular mechanism of OA pathogenesis concerning ubiquitination and deubiquitination, so as to explore novel potential therapeutic targets of OA treatment.

Banxia Xiexin Decoction Prevents HT22 Cells from High Glucose-induced Neurotoxicity via JNK/SIRT1/Foxo3a Signaling Pathway

BACKGROUND

Type 2 diabetes-associated cognitive dysfunction (DCD) is a chronic complication of diabetes that has gained international attention. The medicinal compound Banxia Xiexin Decoction (BXXXD) from traditional Chinese medicine (TCM) has shown potential in improving insulin resistance, regulating endoplasmic reticulum stress (ERS), and inhibiting cell apoptosis through various pathways. However, the specific mechanism of action and medical value of BXXXD remain unclear.

METHODS

We utilized TCMSP databases to screen the chemical constituents of BXXXD and identified DCD disease targets through relevant databases. By using Stitch and String databases, we imported the data into Cytoscape 3.8.0 software to construct a protein-protein interaction (PPI) network and subsequently identified core targets through network topology analysis. The core targets were subjected to Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The results were further validated through in vitro experiments.

RESULTS

Network pharmacology analysis revealed the screening of 1490 DCD-related targets and 190 agents present in BXXXD. The topological analysis and enrichment analysis conducted using Cytoscape software identified 34 core targets. Additionally, GO and KEGG pathway analyses yielded 104 biological targets and 97 pathways, respectively. BXXXD exhibited its potential in treating DCD by controlling synaptic plasticity and conduction, suppressing apoptosis, reducing inflammation, and acting as an antioxidant. In a high glucose (HG) environment, the expression of JNK, Foxo3a, SIRT1, ATG7, Lamp2, and LC3 was downregulated. BXXXD intervention on HT22 cells potentially involved inhibiting excessive oxidative stress, promoting neuronal autophagy, and increasing the expression levels of JNK, SIRT1, Foxo3a, ATG7, Lamp2, and LC3. Furthermore, the neuroprotective effect of BXXXD was partially blocked by SP600125, while quercetin enhanced the favorable role of BXXXD in the HG environment.

CONCLUSION

BXXXD exerts its effects on DCD through multiple components, targets, levels, and pathways. It modulates the JNK/SIRT1/Foxo3a signaling pathway to mitigate autophagy inhibition and apoptotic damage in HT22 cells induced by HG. These findings provide valuable perspectives and concepts for future clinical trials and fundamental research.

Advanced Progress of the Relationship Between Antihypertensive Drugs and Bone Metabolism

Hypertension and osteoporosis are common comorbidities among elderly individuals. Drug therapy has been widely used in clinical practice as the preferred antihypertensive treatment. Therefore, antihypertensive drugs have become some of the most commonly prescribed drugs in healthcare settings. However, antihypertensive drugs have different effects on bone metabolism. The results of animal and clinical studies on the effects of antihypertensive drugs on osteoporosis or fracture risk are controversial and have aroused widespread concern among clinicians. Recent studies found that angiotensin receptor blockers, selective β-adrenergic receptor blockers, and thiazide diuretics might improve bone trabecular number and bone mineral density by stimulating osteoblast differentiation, reducing osteoclast generation, and other mechanism. Furthermore, nonselective β-adrenergic receptor blockers and dihydropyridine calcium channel blockers were found to have no significant relationship with bone mineral density or bone strength, and α-adrenergic receptor blockers and loop diuretics might increase fracture risk by decreasing bone mineral density. This article aimed to review previous animal experiments, clinical studies, and meta-analyses focusing on the effects of different antihypertensive drugs on bone metabolism, and to provide a new approach for the prevention and treatment of osteoporosis.

Mitochondrial quality control and its role in osteoporosis

Mitochondria are important organelles that provide cellular energy and play a vital role in cell differentiation and apoptosis. Osteoporosis is a chronic metabolic bone disease mainly caused by an imbalance in osteoblast and osteoclast activity. Under physiological conditions, mitochondria regulate the balance between osteogenesis and osteoclast activity and maintain bone homeostasis. Under pathological conditions, mitochondrial dysfunction alters this balance; this disruption is important in the pathogenesis of osteoporosis. Because of the role of mitochondrial dysfunction in osteoporosis, mitochondrial function can be targeted therapeutically in osteoporosis-related diseases. This article reviews different aspects of the pathological mechanism of mitochondrial dysfunction in osteoporosis, including mitochondrial fusion and fission, mitochondrial biogenesis, and mitophagy, and highlights targeted therapy of mitochondria in osteoporosis (diabetes induced osteoporosis and postmenopausal osteoporosis) to provide novel targets and prevention strategies for the prevention and treatment of osteoporosis and other chronic bone diseases.

Potential Role of Lisinopril in Reducing Atherosclerotic Risk: Evidence of an Antioxidant Effect in Human Cardiomyocytes Cell Line

The cellular mechanisms involved in myocardial ischemia/reperfusion injury (I/R) pathogenesis are complex but attributable to reactive oxygen species (ROS) production. ROS produced by coronary endothelial cells, blood cells (e.g., leukocytes and platelets), and cardiac myocytes have the potential to damage vascular cells directly and cardiac myocytes, initiating mechanisms that induce apoptosis, inflammation, necrosis, and fibrosis of myocardial cells. In addition to reducing blood pressure, lisinopril, a new non-sulfhydryl angiotensin-converting enzyme (ACE) inhibitor, increases the antioxidant defense in animals and humans. Recently, it has been shown that lisinopril can attenuate renal oxidative injury in the l-NAME-induced hypertensive rat and cause an impressive improvement in the antioxidant defense system of Wistar rats treated with doxorubicin. The potential effect of lisinopril on oxidative damage and fibrosis in human cardiomyocytes has not been previously investigated. Thus, the present study aims to investigate the effect of different doses of lisinopril on oxidative stress and fibrotic mediators in AC16 human cardiomyocytes, along with a 7-day presence in the culture medium. The results revealed that AC16 human cardiomyocytes exposed to lisinopril treatment significantly showed an upregulation of proteins involved in protecting against oxidative stress, such as catalase, SOD2, and thioredoxin, and a reduction of osteopontin and Galectin-3, critical proteins involved in cardiac fibrosis. Moreover, lisinopril treatment induced an increment in Sirtuin 1 and Sirtuin 6 protein expression. These findings demonstrated that, in AC16 human cardiomyocytes, lisinopril could protect against oxidative stress and fibrosis via the activation of Sirtuin 1 and Sirtuin 6 pathways.

Salidroside prevents PM2.5-induced BEAS-2B cell apoptosis via SIRT1-dependent regulation of ROS and mitochondrial function

PM2.5 is a harmful air pollutant currently threatening public health. It has been closely linked to increased morbidity of bronchial asthma and lung cancer worldwide. Salidroside (Sal), an active component extracted from Rhodiola rosea, has been reported to ameliorate the progression of asthma. However, there are few studies on the protective effect of salidroside on PM2.5-induced bronchial epithelial cell injury, and the related molecular mechanism is not clear. Here, we aimed to explore the protective effect and related mechanism of Sal on PM2.5 bronchial injury. We chose 50 μg/mL PM2.5 for 24 h as a PM2.5-induced cell damage model. After that BEAS-2B cells were pretreated with 40, 80, 160 µM Sal for 24 h and then exposed to 50 μg/mL PM2.5 for 24 h. We found that Sal pretreatment significantly inhibited the decrease of cell viability induced by PM2.5. Sal was effective in preventing PM2.5-induced apoptotic features, including Ca²⁺ overload, the cleavages of caspase 3, and the increases in levels of caspase 9 and Bcl-2-associated X protein (Bax), ultimately, Sal significantly inhibited PM2.5-induced apoptosis. Sal improved mitochondrial membrane potential, inhibited the release of cytochrome c from the mitochondria to cytoplasm. Sal alleviated ROS production, decreased the level of MDA, prevented the reduction of CAT, SOD and GSH-Px and increased the expression of NF-E2-related factor 2 (Nrf2), HO-1 and superoxide dismutase 1 (SOD1) in cells exposed to PM2.5. Furthermore, Sal improved the decrease of SIRT1 and PGC-1 α expression levels caused by PM2.5. In addition, inhibition of SIRT1 by EX527 (SIRT1 inhibitor) reversed the protective effects of Sal, including the decrease of ROS level, the increase of membrane potential level and the decrease of apoptosis level. Thus, Sal may be regarded as a potential drug to prevent PM2.5-induced apoptosis of bronchial epithelial cells and other diseases with similar pathological mechanisms.

Ubiquitin-specific protease 3 attenuates interleukin-1β-mediated chondrocyte senescence by deacetylating forkhead box O-3 via sirtuin-3

Osteoarthritis (OA) affects approximately 12% of the aging Western population. The sirtuin/forkhead box O (SIRT/FOXO) signaling pathway plays essential roles in various biological processes. Despite it has been demonstrated that ubiquitin-specific protease 3 (USP3) inhibits chondrocyte apoptosis induced by interleukin (IL)-1β, the role of USP3/SIRT3/FOXO3 in the senescence of chondrocytes in OA is unclear. This study initially isolated articular chondrocytes and investigated the role of USP3 in IL-1β-induced senescence of chondrocytes. After USP3 was overexpressed or silenced by lentivirus, expressions of genes and proteins were detected using quantitative polymerase chain reaction and immunoblotting, respectively. Cell cycle analysis was performed using flow cytometry. Reactive oxygen species (ROS) levels and senescence were analyzed. Then, SIRT3 was inhibited or overexpressed to explore the underlying mechanism. We found that overexpression of USP3 hindered IL-1β-mediated cell cycle arrest, ROS generation, and chondrocyte senescence. The inhibition of SIRT3 blocked the protective effect of USP3 on cell senescence, whereas the overexpression of SIRT3 abolished USP3-silencing-induced cell senescence. Furthermore, SIRT3 attenuated cell senescence, probably by deacetylating FOXO3. USP3 upregulated SIRT3 to deacetylate FOXO3 and attenuated IL-1β-induced chondrocyte senescence. This study demonstrated that USP3 probably attenuated IL-1β-mediated chondrocyte senescence by deacetylating FOXO3 via SIRT3.

Associations of multiple metals with bone mineral density: A population-based study in US adults

Epidemiologic studies focus on combined effects of multiple metals on bone mineral density (BMD) are scarce. Therefore, this study was conducted to examine associations of multiple metals exposure with BMD. Data of adults aged ≥20 years (n = 2545) from the US National Health and Nutrition Examination Survey (NHANES, 2011-2016) were collected and analyzed. Concentrations of metals were measured in blood (cadmium [Cd], lead [Pb], mercury [Hg], and manganese [Mn]) and serum (copper [Cu], selenium [Se], and zinc [Zn]) using inductively coupled plasma mass spectrometry and inductively coupled plasma dynamic reaction cell mass spectrometry, respectively. The weighted quantile sum (WQS) and Bayesian kernel machine regression (BKMR) models were performed to determine the joint effects of multiple metals exposure on lumbar and total BMD. The linear regression analyses showed Pb was negatively associated with BMDs. The WQS regression analyses revealed that the WQS index was inversely related to lumbar (β = -0.022, 95% CI: -0.036, -0.008) and total BMD (β = -0.015, 95% CI: -0.024, -0.006), and Se, Mn, and Pb were the main contributors for the combined effects. Additionally, nonlinear dose-response relationships between Pb, Mn, and Se and BMD, as well as a synergistic interaction of Pb and Mn, were found in the BKMR analyses. Our findings suggested co-exposure to Cd, Pb, Hg, Mn, Cu, Se, and Zn (above their 50th percentiles) was associated with reduced BMD, and Pb, Mn, and Se were the main contributors driving the overall effects.

Tissue Renin-Angiotensin System (tRAS) Induce Intervertebral Disc Degeneration by Activating Oxidative Stress and Inflammatory Reaction

Lumbar intervertebral disc degeneration (IDD) has been the major contributor to low back pain (LBP). IDD is an chronic inflammation process, with the activation of plentiful inflammation-related cytokines and ECM degradation-related enzymes. In the past few years, hypertension has been reported to correlate with LBP. In addition, the local tissue renin-angiotensin system (tRAS) has been identified in multiple tissues, including the spinal cord, skin, kidney, heart, and bone. Recently, tRAS has also been established in both bovine and human intervertebral disc tissues, especially in the degenerated disc tissue. However, the exact of tRAS and IDD remains unknown. In this present study, proteomic analysis, molecular biology analysis, and animal model were all used. Firstly, we revealed that tRAS was excessively activated in the human degenerated intervertebral disc tissue via proteomic analysis and molecular biology analysis. Then, in vitro experiment suggested that Ang II could decrease the cell viability of human NP cells and promote NP cell apoptosis, senescence, oxidative stress, and NLRP3 activation in human NP cells. In addition, Ang II could also trigger degeneration and fibrosis phenotype in human NP cells. Finally, the animal model demonstrated that the local activated ACE/Ang II axis in the NP tissue could accelerate IDD in aging spontaneously hypertensive rats (SHR). Collectively, the degenerated intervertebral disc tissue showed excessively activated tRAS, and local activated tRAS could induce NP cell senescence, apoptosis, oxidative stress, and inflammatory reaction to promote IDD. These biological effects of Ang II on human NP cells may provide novel insight into further treatment of IDD.

The Roles of Epigenetics Regulation in Bone Metabolism and Osteoporosis

Osteoporosis is a metabolic disease characterized by decreased bone mineral density and the destruction of bone microstructure, which can lead to increased bone fragility and risk of fracture. In recent years, with the deepening of the research on the pathological mechanism of osteoporosis, the research on epigenetics has made significant progress. Epigenetics refers to changes in gene expression levels that are not caused by changes in gene sequences, mainly including DNA methylation, histone modification, and non-coding RNAs (lncRNA, microRNA, and circRNA). Epigenetics play mainly a post-transcriptional regulatory role and have important functions in the biological signal regulatory network. Studies have shown that epigenetic mechanisms are closely related to osteogenic differentiation, osteogenesis, bone remodeling and other bone metabolism-related processes. Abnormal epigenetic regulation can lead to a series of bone metabolism-related diseases, such as osteoporosis. Considering the important role of epigenetic mechanisms in the regulation of bone metabolism, we mainly review the research progress on epigenetic mechanisms (DNA methylation, histone modification, and non-coding RNAs) in the osteogenic differentiation and the pathogenesis of osteoporosis to provide a new direction for the treatment of bone metabolism-related diseases.

Organelle dynamics of endothelial mitochondria in diabetic angiopathy

Diabetes, a chronic non-communicable disease, has become one of the most serious and critical public health problems with increasing incidence trends. Chronic vascular complications are the major causes of disability and death in diabetic patients with endothelial dysfunction. Diabetes is intimately associated with endothelial mitochondrial dysfunction, indicated by increased oxidative stress, decreased biogenesis, increased DNA damage, and weakened autophagy in mitochondria. All these morphological and functional changes of mitochondria play important roles in diabetic endothelial dysfunction. Herein, we reviewed the roles and mechanisms of endothelial mitochondrial dysfunction, particularly mitochondrial dynamics in the vascular complications of diabetes and summarized the potential mitochondria-targeted therapies in diabetic vascular complications.

SIRT1, a promising regulator of bone homeostasis

Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase, epigenetically regulates various cell metabolisms, including inflammation, tumorigenesis, and bone metabolism. Many clinical studies have found the potential of SIRT1 in predicting and treating bone-related disorders, such as osteoporosis and osteonecrosis, suggesting that SIRT1 might be a regulator of bone homeostasis. In order to identify the mechanisms that underlie the pivotal role of SIRT1 in bone homeostasis, many studies revealed that SIRT1 could maintain the balance between bone formation and absorption via regulating the ratio of osteoblasts to osteoclasts. SIRT1 controls the differentiation of mesenchymal stem cells (MSCs) and bone marrow-derived macrophages, increasing osteogenesis and reducing osteoclastogenesis. Besides, SIRT1 can enhance bone-forming cells' viability, including MSCs and osteoblasts under adverse conditions by resisting senescence, suppressing apoptosis, and promoting autophagy in favor of osteogenesis. Furthermore, the effect on bone vasculature homeostasis enables SIRT1 to become a valuable strategy for ischemic osteonecrosis and senile osteoporosis. The review systemically discusses SIRT1 pathways and the critical role in bone homeostasis and assesses whether SIRT1 is a potential target for manipulation and therapy, to lay a solid foundation for further researches in the future.

Echinacoside reverses myocardial remodeling and improves heart function via regulating SIRT1/FOXO3a/MnSOD axis in HF rats induced by isoproterenol

Myocardial remodelling is important pathological basis of HF, mitochondrial oxidative stress is a promoter to myocardial hypertrophy, fibrosis and apoptosis. ECH is the major active component of a traditional Chinese medicine Cistanches Herba, plenty of studies indicate it possesses a strong antioxidant capacity in nerve cells and tumour, it inhibits mitochondrial oxidative stress, protects mitochondrial function, but the specific mechanism is unclear. SIRT1/FOXO3a/MnSOD is an important antioxidant axis, study finds that ECH binds covalently to SIRT1 as a ligand and up-regulates the expression of SIRT1 in brain cells. We hypothesizes that ECH may reverse myocardial remodelling and improve heart function of HF via regulating SIRT1/FOXO3a/MnSOD signalling axis and inhibit mitochondrial oxidative stress in cardiomyocytes. Here, we firstly induce cellular model of oxidative stress by ISO with AC-16 cells and pre-treat with ECH, the level of mitochondrial ROS, mtDNA oxidative injury, MMP, carbonylated protein, lipid peroxidation, intracellular ROS and apoptosis are detected, confirm the effect of ECH in mitochondrial oxidative stress and function in vitro. Then, we establish a HF rat model induced by ISO and pre-treat with ECH. Indexes of heart function, myocardial remodelling, mitochondrial oxidative stress and function, expression of SIRT1/FOXO3a/MnSOD signalling axis are measured, the data indicate that ECH improves heart function, inhibits myocardial hypertrophy, fibrosis and apoptosis, increases the expression of SIRT1/FOXO3a/MnSOD signalling axis, reduces the mitochondrial oxidative damages, protects mitochondrial function. We conclude that ECH reverses myocardial remodelling and improves cardiac function via up-regulating SIRT1/FOXO3a/MnSOD axis and inhibiting mitochondrial oxidative stress in HF rats.

Association between long-term occupational manganese exposure and bone quality among retired workers

Despite well documents for manganese-induced neurological deficits, limited researches are available for effects of manganese (Mn) exposure on the bone. Here we aimed to explore the associations between long-term occupational Mn exposure and bone quality among retired workers. We conducted a cross-sectional study of 304 exposed subjects (n, male = 161 and female = 143) and 277 control retired workers (n, male = 65 and female = 212) recruited from a ferromanganese refinery. Self-reported occupation types were used as exposure classification confirmed by expert consultation. Bone quality was measured by quantitative ultrasound (QUS). In sex-stratified analyses throughout, stiffness index (SI) and T-score levels of the participants in the highest exposed group [tertile 3 of Mn cumulative exposure index (Mn-CEI)] were significantly lower as compared with the control group among female workers (SI, mean, 61.60 vs. 68.17; T-score, mean, -3.01 vs. -2.34, both P < 0.05). In addition, SI and T-score were found to be negatively associated with Mn-CEI only in the highest exposure group as compared with the female controls (both P = 0.01). However, we did not find the significant difference for SI or T-score among the male subjects in exposure models and the male controls (P > 0.05). Our results suggest that female retired workers in the highest Mn-exposed model (tertile 3 of Mn-CEI) potentially experience a higher risk of developing osteoporosis compared with the female controls. Further investigations on possible mechanisms on bone quality alteration are needed in the future.

MnTBAP inhibits bone loss in ovariectomized rats by reducing mitochondrial oxidative stress in osteoblasts

The development of postmenopausal osteoporosis is thought to be closely related to oxidative stress. Mn(III)tetrakis (4-benzoic acid) porphyrin (MnTBAP), a novel superoxide dismutase (SOD) mimetic, could protect osteoblasts from cytotoxicity and dysfunction caused by oxidative stress. However, it is still unclear whether MnTBAP has effect on the development of postmenopausal osteoporosis. Here, we demonstrated that MnTBAP can inhibit bone mass loss and bone microarchitecture alteration, and increase the number of osteoblasts while reducing osteoclasts number, as well as improve the BMP-2 expression level in ovariectomized rat model. Additionally, MnTBAP can also prevent oxidative stress status up-regulation induced by ovariotomy and hydrogen peroxide (H₂O₂). Furthermore, MnTBAP reduced the effect of oxidative stress on osteoblasts differentiation and increased BMP-2 expression levels with a dose-dependent manner, via reducing the levels of mitochondrial oxidative stress in osteoblasts. Taken together, our findings provide new insights that MnTBAP inhibits bone loss in ovariectomized rats by reducing mitochondrial oxidative stress in osteoblasts, and maybe a potential drug in postmenopausal osteoporosis therapy.

The renin-angiotensin aldosterone system and osteoporosis: findings from the Women's Health Initiative

New users of RAAS inhibitors, including ACE inhibitors and ARBs, have a small increased risk for fracture in the first 3 years of use, with a reduced risk of fracture with longer duration of use.

INTRODUCTION

Pharmacological inhibitors of the renin-angiotensin aldosterone system (RAAS) are used to treat hypertension. However, the relationship of these medications to osteoporosis is inconsistent, and no study has included simultaneous measurements of both incident fractures and bone mineral density (BMD).

METHODS

The association of RAAS inhibitor use (n = 131,793) with incident fractures in new users of these medications in women in the Women's Health Initiative over a minimum median follow-up of 6.5 years was assessed by Cox proportional hazard models. The association of incident fractures by a cumulative duration of use of these medications (< 3 years.) and (> 3 years.) was also estimated. Subgroup analysis of fracture risk by RAAS inhibitor use confined to women with hypertension was also performed (n = 33,820). The association of RAAS inhibitor use with changes in BMD of the hip was estimated by linear regression in 8940 women with dual energy X-ray absorptiometry measurements.

RESULTS

There was no significant association between RAAS inhibitor use and all fractures in the final adjusted multivariable models including hip BMD (HR 0.86 (0.59, 1.24)). However, among users of RAAS inhibitors, including ACE inhibitors and angiotensin receptor blockers (ARBs), hazard ratios for all incident fracture sites in final multivariable models including hip BMD showed dramatic differences by duration of use, with short duration of use (3 years or less) associated with a marked increased risk for fracture (HR 3.28 (1.66, 6.48)) to (HR 6.23 (3.11, 12.46)) and use for more than 3 years associated with a reduced fracture risk (HR 0.40 (0.24, 0.68) to (HR 0.44 (0.20, 0.97)) . Findings were similar in the subgroup of women with a history of hypertension. There was no significant change in BMD of the hip by RAAS inhibitor use.

CONCLUSIONS

In postmenopausal women, use of RAAS inhibitors, including ACE inhibitors and ARBs, is associated with an increased risk for fracture among new users of these medications in the first 3 years of use. However, long-term use (> 3 years) is associated with a reduced risk. Consideration for fracture risk may be part of the decision-making process for initiation of these medications for other disease states.

Arsenic trioxide inhibits angiogenesis in vitro and in vivo by upregulating FoxO3a

Arsenic trioxide (As₂O₃) has been used clinically for the treatment of acute promyelocytic leukemia and some solid tumors. However, the mechanisms of its anti-tumor effects are still elusive. Angiogenesis is a key process for tumor initiation, and increasing evidence has supported the role of anti-angiogenesis caused by arsenic in tumor suppression, although the detailed mechanism is not well understood. In the present study, we found that As₂O₃ significantly inhibited the angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro, and this was mediated by the upregulation of FoxO3a. Knockdown of FoxO3a could restore the angiogenic ability of HUVECs. Moreover, vascular endothelial cell-specific knockout of FoxO3a in mice could disrupt the anti-angiogenesis effect of As₂O₃ and endow the tumors with resistance to As₂O₃ treatments. Our results revealed a new mechanism by which As₂O₃ suppresses angiogenesis and tumor growth.

Chlorogenic acid prevents paraquat-induced apoptosis via Sirt1-mediated regulation of redox and mitochondrial function

Paraquat (PQ) is a widely used agro-chemical in agriculture and highly toxic to humans. Although the mechanism of PQ poisoning is not clear, it has been well documented that reactive oxygen species (ROS) generation and apoptosis play pivotal roles. Alternatively, chlorogenic acid (CA) is a biologically active dietary polyphenol, playing several therapeutic roles. However, it is not known whether CA has protective effect on PQ-induced apoptosis. Here, we investigated the effect of CA in preventing PQ-induced apoptosis and explored the underlying mechanisms. A549 cells were pretreated with 100 µM CA for 24 h and then exposed to 160 µM PQ for 24 h. We found that CA was effective in preventing PQ-induced apoptotic features, including the release of cytochrome c from the mitochondria to cytoplasm, the cleavages of caspase 3 and caspase 9, and the increases in levels of Bcl-2-associated X protein (Bax) and intracellular calcium ions. CA alleviated ROS production and prevented the reduction of antioxidant capacity in cells exposed to PQ by increasing NF-E2-related factor 2 (Nrf2), superoxide dismutase 2 (SOD2) and glutathione levels. In addition, CA also attenuated PQ-induced alterations of mitochondrial structure and function (such as the decreases in membrane potential and adenosine triphosphate level), and the impaired autophagic flux was improved by CA. Down-regulation of sirtuin 1 (Sirt1) by short hairpin RNA reversed the protective effects of CA. Thus, CA may be viewed as a potential drug to treat PQ-induced lung epithelial cell apoptosis and other disorders with similar pathologic mechanisms.

Sirt1/Foxo Axis Plays a Crucial Role in the Mechanisms of Therapeutic Effects of Erzhi Pill in Ovariectomized Rats

Background. Erzhi pill (EZP), a traditional Chinese herbal formula, has been widely used to treat postmenopausal osteoporosis (PMOP) in China. However, its molecular mechanisms remain unclear. The aim of the present study is to investigate the antiosteoporotic effect of EZP on an ovariectomized rat model of PMOP. We performed the biomarkers of bone metabolism disorder, bone morphology, bone mineral density (BMD), and bone biomechanics to confirm the successful establishment of the PMOP model. We then investigated the expression of biomarkers related to the Sirt1/Foxo axis. We also examined microRNA-132 (miR-132), a regulator in the Sirtuin1 (Sirt1) expression. The bone metabolism disorder, bone morphology, BMD, and bone biomechanics in ovariectomized rats were improved by EZP administration. The antiosteoporotic effect of EZP was confirmed. We also found that the expressions of Sirt1, Runx2, Foxo1, and Foxo3a were downregulated in ovariectomized rats, while being then upregulated by EZP administration. And the expression of PPAR-γ and miR-132 was upregulated in ovariectomized rats and then downregulated by EZP administration. These results provided evidence that Sirt1/Foxo axis related mechanism may play a crucial role in the therapeutic effects of EZP, indicating that Sirt1/Foxo axis can be considered as a potential therapeutic target for PMOP in the future.

The GDF11-FTO-PPARγ axis controls the shift of osteoporotic MSC fate to adipocyte and inhibits bone formation during osteoporosis

During osteoporosis, the shift of bone mesenchymal stem cell (BMSC) lineage commitment to adipocyte leads to the imbalance between bone mass and fat, which increases the risk of fracture. The mechanism underlying this process is not fully understood. Fat mass and obesity-associated protein (FTO) is an RNA demethylase that demethylates various methylated nucleic acids and participates in various physiological and pathological processes. Here we identified FTO as a regulator for BMSC fate determination during osteoporosis. FTO was up-regulated in bone marrow during aging or osteoporosis in human and mice in a GDF11(growth differentiation factor 11)-C/EBPα-dependent mechanism. The expression of FTO was also up-regulated during adipocyte differentiation of BMSCs whereas its expression was down-regulated during osteoblast differentiation. Gain-of-function and loss-of-function experiments showed that FTO favored the BMSCs to differentiate to adipocytes rather than osteoblasts. Further mechanism study demonstrated that FTO bound and demethylated the mRNA of the Peroxisome proliferator-activated receptor gamma (Pparg), leading to the increase in the expression of Pparg mRNA. Reversely, Pparg knockdown blocked the function of GDF11-FTO during osteoblast differentiation of BMSCs. Furthermore, conditionally genetic knockout of Fto in osteoblasts inhibited the development of osteopenia in mice. Collectively, our findings demonstrated that GDF11-FTO-Pparg axis promoted the shift of osteoporotic BMSC fate to adipocyte and inhibited bone formation during osteoporosis.

FOXO3a is essential for murine endometrial decidualization through cell apoptosis during early pregnancy

Embryo implantation is essential for normal pregnancy, and the process of decidualization is critical for embryo implantation. However, the mechanism of decidualization during early pregnancy is still unknown. Forkhead box O3a (FOXO3a) is the most important functional transcription factor of the forkhead box family and is a highly conserved transcription factor of apoptosis-related genes. In the mouse uterus, FOXO3a was found to be expressed regularly from Days 1-7 of early pregnancy. Upon further exploration, it was found that FOXO3a was expressed at significantly higher levels at the implantation site than at the interimplantation site on Days 5-7 of pregnancy. Under artificial decidualization, FOXO3a was highly expressed in the first and second decidual zones. After decidualization, the expression of FOXO3a was significantly increased both in vivo and vitro. In primary stromal cells, apoptosis was reduced by decreased expression of FOXO3a after inducing decidualization. Moreover, when FOXO3a-small interfering RNA was transfected into the uteri of mice, the expression of decidualization- and apoptosis-related factors was impaired. Thus, FOXO3a might play an important role in decidualization during early pregnancy, and cell apoptosis might be one of pathways for FOXO3a-regulated decidualization.

Fructose-rich diet differently affects angiotensin II receptor content in the nucleus and a plasma membrane fraction of visceral adipose tissue

The adipose tissue renin-angiotensin system (RAS) is proposed to be a pathophysiological link between adipose tissue dysregulation and metabolic disorders induced by a fructose-rich diet (FRD). RAS can act intracellularly. We hypothesized that adipocyte nuclear membranes possess angiotensin receptor types 1 and 2 (AT1R and AT2R), which couple to nuclear signaling pathways and regulate oxidative gene expression under FRD conditions. We analyzed the effect of consumption of 10% fructose solution for 9 weeks on biochemical parameters, adipocyte morphology, and expression of AT1R, AT2R, AT1R-associated protein (ATRAP), NADPH oxidase 4 (NOX4), matrix metalloproteinase-9 (MMP-9), and manganese superoxide dismutase (MnSOD) in adipose tissue of Wistar rats. We detected AT1R and AT2R in the nuclear fraction. FRD reduced the level of angiotensin receptors in the nucleus, while increased AT1R and decreased AT2R levels were observed in the plasma membrane. FRD increased the ATRAP mRNA level and decreased MnSOD mRNA and protein levels. No significant differences were observed for MMP-9 and NOX4 mRNA levels. These findings coincided with hyperleptinemia, elevated blood pressure and triglycerides, and unchanged visceral adipose tissue mass and morphology in FRD rats. Besides providing evidence for nuclear localization of angiotensin receptors in visceral adipose tissue, this study demonstrates the different effects of FRD on AT1R expression in different cellular compartments. Elevated blood pressure and decreased antioxidant capacity in visceral fat of fructose-fed rats were accompanied by an increased AT1R level in the plasma membrane, while upregulation of ATRAP and a decrease of nuclear membrane AT1R suggest an increased capacity for attenuation of excessive AT1R signaling and visceral adiposity.

Effects of berberine on the growth and immune performance in response to ammonia stress and high-fat dietary in blunt snout bream Megalobrama amblycephala

This study aimed to figure out the effects of berberine on growth performance, immunity, oxidative stress and hepatocyte apoptosis of blunt snout bream (Megalobrama amblycephala) fed with high-fat diet. 320 fish (80.00 ± 0.90 g) were divided randomly into four trial groups (each with four replicates) and fed with 4 diets (normal diet, normal diet with 50 mg/kg berberine, high-fat diet, high-fat diet with 50 mg/kg berberine), respectively. At the end of the feeding trial, ammonia stress test was carried out for 5 days. The result showed the growth performance, immune parameters including plasm acid phosphatase (ACP) activities, lysozyme (LYZ) activities and alternative complement C3 and C4 contents were suppressed in fish fed with high-fat diets but improved in berberine diets compared with control (normal diet). Hepatopancreas oxidative status, the malondialdehyde (MDA), protein carbonyl (PC) and lipid peroxide (LPO) were increased significantly (P < 0.05) when fish were fed with high-fat diets. Berberine could slow the progression of the oxidative stress induced by high-fat through increasing superoxide dismutase (SOD) activities and total sulfydryl (T-SH) levels of fish. And the hepatocyte apoptosis in the high-fat group could also be alleviated by berberine. After the ammonia stress test, the accumulative mortality was extremely (P < 0.05) low in fish fed high-fat diet with berberine compared to other groups. It was concluded berberine as a functional feed additive significantly inhibited the progression of oxidative stress, reduced the apoptosis and enhanced the immunity of fish fed with high-fat diet.

Chikusetsu saponin V attenuates H2O2-induced oxidative stress in human neuroblastoma SH-SY5Y cells through Sirt1/PGC-1α/Mn-SOD signaling pathways

Oxidative stress plays a vital role in the pathogenesis of neurodegenerative diseases. Chikusetsu saponin V (CsV), the most abundant member of saponins from Panax japonicus (SPJ), has attracted increasing attention for its potential to treat neurodegenerative diseases. However, the mechanisms are unclear. Our study intended to investigate the antioxidative effects of CsV in human neuroblastoma SH-SY5Y cells. Our data showed that CsV attenuated H2O2-induced cytotoxicity, inhibited ROS accumulation, increased the activities of superoxide dismutase (SOD) and GSH, and increased mitochondrial membrane potential dose-dependently. Further exploration of the mechanisms showed that CsV exhibited these effects through increasing the activation of oxidative-stress-associated factors including Sirt1, PGC-1α, and Mn-SOD. Moreover, CsV inhibited H2O2-induced down-regulation of Bcl-2 and up-regulation of Bax in a dose-dependent manner and, thus, increased the ratio of Bcl-2/Bax. In conclusion, our study demonstrated that CsV exhibited neuroprotective effects possibly through Sirt1/PGC-1α/Mn-SOD signaling pathways.

Hypertension and aging

Hypertension is a highly prevalent condition with numerous health risks, and the incidence of hypertension is greatest among older adults. Traditional discussions of hypertension have largely focused on the risks for cardiovascular disease and associated events. However, there are a number of collateral effects, including risks for dementia, physical disability, and falls/fractures which are increasingly garnering attention in the hypertension literature. Several key mechanisms--including inflammation, oxidative stress, and endothelial dysfunction--are common to biologic aging and hypertension development and appear to have key mechanistic roles in the development of the cardiovascular and collateral risks of late-life hypertension. The objective of the present review is to highlight the multi-dimensional risks of hypertension among older adults and discuss potential strategies for treatment and future areas of research for improving overall care for older adults with hypertension.

Effect of amlodipine, lisinopril and allopurinol on acetaminophen-induced hepatotoxicity in rats

Background

Exposure to chemotherapeutic agents such as acetaminophen may lead to serious liver injury. Calcium deregulation, angiotensin II production and xanthine oxidase activity are suggested to play mechanistic roles in such injury.

Objective

This study evaluates the possible protective effects of the calcium channel blocker amlodipine, the angiotensin converting enzyme inhibitor lisinopril, and the xanthine oxidase inhibitor allopurinol against experimental acetaminophen-induced hepatotoxicity, aiming to understand its underlying hepatotoxic mechanisms.

Material and methods

Animals were allocated into a normal control group, a acetaminophen hepatotoxicity control group (receiving a single oral dose of acetaminophen; 750 mg/kg/day), and four treatment groups receive N-acetylcysteine (300 mg/kg/day; a reference standard), amlodipine (10 mg/kg/day), lisinopril (20 mg/kg/day) and allopurinol (50 mg/kg/day) orally for 14 consecutive days prior to acetaminophen administration. Evaluation of hepatotoxicity was performed by the assessment of hepatocyte integrity markers (serum transaminases), oxidative stress markers (hepatic malondialdehyde, glutathione and catalase), and inflammatory markers (hepatic myeloperoxidase and nitrate/nitrite), in addition to a histopathological study.

Results

Rats pre-treated with amlodipine, lisinopril or allopurinol showed significantly lower serum transaminases, significantly lower hepatic malondialdehyde, myeloperoxidase and nitrate/nitrite, as well as significantly higher hepatic glutathione and catalase levels, compared with acetaminophen control rats. Serum transaminases were normalized in the lisinopril treatment group, while hepatic myeloperoxidase was normalized in the all treatment groups. Histopathological evaluation strongly supported the results of biochemical estimations.

Conclusion

Amlodipine, lisinopril or allopurinol can protect against acetaminophen-induced hepatotoxicity, showing mechanistic roles of calcium channels, angiotensin converting enzyme and xanthine oxidase enzyme in the pathogenesis of hepatotoxicity induced by acetaminophen.