Hydrogen gas protects against ovariectomy-induced osteoporosis by inhibiting NF-κB activation

The Biological Effects of Magnesium-Based Implants on the Skeleton and Their Clinical Implications in Orthopedic Trauma Surgery

Magnesium (Mg)-based implants have evolved as a promising innovation in orthopedic trauma surgery, with the potential to revolutionize the treatment of bone diseases, including osteoporotic fractures and bone defects. Available clinical studies mostly show excellent patient outcomes of resorbable Mg-based implants, without the need for subsequent implant removal. However, the occurrence of radiolucent zones around Mg-based implants seems to be a noticeable drawback for a more widespread clinical use. Mechanistically, both in vivo and in vitro studies demonstrated beneficial effects on the formation of new bone, a unique characteristic of Mg-based implants. In this regard, Mg has been shown to exert pleiotropic functions on osteogenic differentiation and migration of osteoblasts and their precursors. Additionally, collective evidence suggests that Mg-based implants promote angiogenesis in newly formed bone and exert immunomodulatory effects in the bone microenvironment. Likewise, Mg-based implants and their degradation products were shown to inhibit bone resorption by impairing osteoclastogenesis. The purpose of this review is to provide a state-of-the-art summary of the clinical and basic science evidence regarding the performance of currently used Mg-based implants. In addition to the status of in vivo and in vitro research and clinical applications, future challenges and perspectives of Mg-based orthopedic implants are discussed.

Exploring cytokines dynamics: Uncovering therapeutic concepts for metabolic disorders in postmenopausal women- diabetes, metabolic bone diseases, and non-alcohol fatty liver disease

Menopause is an age-related change that persists for around one-third of a woman's life. Menopause increases the risk of metabolic illnesses such as diabetes, osteoporosis (OP), and nonalcoholic fatty liver disease (NAFLD). Immune mediators (pro-inflammatory cytokines), such as interleukin-1 (IL-1), IL-6, IL-17, transforming growth factor (TGF), and tumor necrosis factor (TNF), exacerbate the challenges of a woman undergoing menopause by causing inflammation and contributing to the development of these metabolic diseases in postmenopausal women. Furthermore, studies have shown that anti-inflammatory cytokines such as interleukin-1 receptor antagonists (IL-1Ra), IL-2, and IL-10 have a double-edged effect on diabetes and OP. Likewise, several interferon (IFN) members are double-edged swords in the OP. Therefore, addressing these immune mediators precisely may be an approach to improving the health of postmenopausal women. Hence, considering the significant changes in these cytokines, the present review focuses on the latest findings concerning the molecular mechanisms by which pro- and anti-inflammatory cytokines (interleukins) impact postmenopausal women with diabetes, OP, and NAFLD. Furthermore, we comprehensively discuss the therapeutic approaches that identify cytokines as therapeutic targets, such as hormonal therapy, physical activities, natural inhibitors (drugs), and others. Finally, this review aims to provide valuable insights into the role of cytokines in postmenopausal women's diabetes, OP, and NAFLD. Deeply investigating the mechanisms and therapeutic interventions involved will address the characteristics of immune mediators (cytokines) and improve the management of these illnesses, thereby enhancing the general quality of life and health of the corresponding populations of women.

N,N-Dimethylformamide inhibits high glucose-induced osteoporosis via attenuating MAPK and NF-κB signalling

Aims

The role of N,N-dimethylformamide (DMF) in diabetes-induced osteoporosis (DM-OS) progression remains unclear. Here, we aimed to explore the effect of DMF on DM-OS development.

Methods

Diabetic models of mice, RAW 264.7 cells, and bone marrow macrophages (BMMs) were established by streptozotocin stimulation, high glucose treatment, and receptor activator of nuclear factor-κB ligand (RANKL) treatment, respectively. The effects of DMF on DM-OS development in these models were examined by micro-CT analysis, haematoxylin and eosin (H&E) staining, osteoclast differentiation of RAW 264.7 cells and BMMs, H&E and tartrate-resistant acid phosphatase (TRAP) staining, enzyme-linked immunosorbent assay (ELISA) of TRAP5b and c-terminal telopeptides of type 1 (CTX1) analyses, reactive oxygen species (ROS) analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR), Cell Counting Kit-8 (CCK-8) assay, and Western blot.

Results

The established diabetic mice were more sensitive to ovariectomy (OVX)-induced osteoporosis, and DMF treatment inhibited the sensitivity. OVX-treated diabetic mice exhibited higher TRAP5b and c-terminal telopeptides of type 1 (CTX1) levels, and DMF treatment inhibited the enhancement. DMF reduced RAW 264.7 cell viability. Glucose treatment enhanced the levels of TRAP5b, cathepsin K, Atp6v0d2, and H⁺-ATPase, ROS, while DMF reversed this phenotype. The glucose-increased protein levels were inhibited by DMF in cells treated with RANKL. The expression levels of antioxidant enzymes Gclc, Gclm, Ho-1, and Nqo1 were upregulated by DMF. DMF attenuated high glucose-caused osteoclast differentiation by targeting mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signalling in BMMs.

Conclusion

DMF inhibits high glucose-induced osteoporosis by targeting MAPK and NF-κB signalling.

Cite this article: Bone Joint Res 2022;11(4):200–209.

Effect of Oxidative Stress-Induced Apoptosis on Active FGF23 Levels in MLO-Y4 Cells: The Protective Role of 17-β-Estradiol

The discovery that osteocytes secrete phosphaturic fibroblast growth factor 23 (FGF23) has defined bone as an endocrine organ. However, the autocrine and paracrine functions of FGF23 are still unknown. The present study focuses on the cellular and molecular mechanisms involved in the complex control of FGF23 production and local bone remodeling functions. FGF23 was assayed using ELISA kit in the presence or absence of 17β–estradiol in starved MLO-Y4 osteocytes. In these cells, a relationship between oxidative stress-induced apoptosis and up-regulation of active FGF23 levels due to MAP Kinases activation with involvement of the transcriptional factor (NF-kB) has been demonstrated. The active FGF23 increase can be due to up-regulation of its expression and post-transcriptional modifications. 17β–estradiol prevents the increase of FGF23 by inhibiting JNK and NF-kB activation, osteocyte apoptosis and by the down-regulation of osteoclastogenic factors, such as sclerostin. No alteration in the levels of dentin matrix protein 1, a FGF23 negative regulator, has been determined. The results of this study identify biological targets on which drugs and estrogen may act to control active FGF23 levels in oxidative stress-related bone and non-bone inflammatory diseases.

Molecular Hydrogen Attenuated N-methyl-N-Nitrosourea Induced Corneal Endothelial Injury by Upregulating Anti-Apoptotic Pathway

Purpose

Previous work by our group has demonstrated the value of N-methyl-N-nitrosourea (MNU)-induced corneal endothelial decompensation in animal models. The aim of this study was to investigate the effect of molecular hydrogen (H2) on MNU-induced corneal endothelial cell (CEC) injury and the underlying mechanism.

Methods

MNU-induced animal models of CEC injury were washed with hydrogen-rich saline (HRS) for 14 days. Immunofluorescence staining, immunohistochemical staining, and corneal endothelial assessment were applied to determine architectural and cellular changes on the corneal endothelium following HRS treatment. MNU-induced cell models of CEC injury were co-cultured with H2. The effect of H2 was examined using morphological and functional assays.

Results

It was shown that MNU could inhibit the proliferation and specific physiological functions of CECs by increasing apoptosis and decreasing the expression of ZO-1 and Na+/K+-ATPase, whereas H2 improved the proliferation and physiological function of CECs by anti-apoptosis. Cell experiments further confirmed that H2 could reverse MNU damage to CECs by decreasing oxidative stress injury, interfering with the NF-κB/NLRP3 pathway and the FOXO3a/p53/p21 pathway.

Conclusions

This study suggests that topical application of H2 could protect CECs against corneal damage factors through anti-apoptotic effect, reduce the incidence and severity of corneal endothelial decompensation, and maintain corneal transparency.

Mechanisms Underlying the Biological Effects of Molecular Hydrogen

Aberrant redox-sensitive reactions and accumulation of oxidative damage can impair body functions and contribute to the development of various pathologies and aging. Although antioxidant substances have long been recognized as a measure of alleviating oxidative stress and restoring redox balance, the arsenal of effective means of preventing the development of various disorders, is still limited. There is an emerging field that utilizes molecular hydrogen (H₂) as a scavenger of free radicals and reactive oxygen species (ROS). Among the remarkable characteristics of H₂ is its ability to counteract the harmful effects of hydroxyl radical and peroxynitrite without affecting the activity of functionally important ROS, such as hydrogen peroxide and nitric oxide. The beneficial effects of H₂ have been documented in numerous clinical studies and studies on animal models and cell cultures. However, the established scavenging activity of H₂ can only partially explain its beneficial effects because the effects are achieved at very low concentrations of H₂. Given the rate of H₂ diffusion, such low concentrations may not be sufficient to scavenge continuously generated ROS. H₂ can also act as a signaling molecule and induce defense responses. However, the exact targets and mechanism(s) by which H₂ exerts these effects are unknown. Here, we analyzed both positive and negative effects of the endogenous H₂, identified the redox-sensitive components of the pathways affected by molecular hydrogen, and also discussed the potential role of molecular hydrogen in regulating cellular redox.

Direct Targets and Subsequent Pathways for Molecular Hydrogen to Exert Multiple Functions: Focusing on Interventions in Radical Reactions

Molecular hydrogen (H₂) was long regarded as non-functional in mammalian cells. We overturned the concept by demonstrating that H₂ exhibits antioxidant effects and protects cells against oxidative stress. Subsequently, it has been revealed that H₂ has multiple functions in addition to antioxidant effects, including antiinflammatory, anti-allergic functions, and as cell death and autophagy regulation. Additionally, H₂ stimulates energy metabolism. As H₂ does not readily react with most biomolecules without a catalyst, it is essential to identify the primary targets with which H₂ reacts or interacts directly. As a first event, H₂ may react directly with strong oxidants, such as hydroxyl radicals (•OH) in vivo. This review addresses the key issues related to this in vivo reaction. •OH may have a physiological role because it triggers a free radical chain reaction and may be involved in the regulation of Ca2+- or mitochondrial ATP-dependent K+-channeling. In the subsequent pathway, H₂ suppressed a free radical chain reaction, leading to decreases in lipid peroxide and its end products. Derived from the peroxides, 4-hydroxy-2-nonenal functions as a mediator that up-regulates multiple functional PGC-1α. As the other direct target in vitro and in vivo, H₂ intervenes in the free radical chain reaction to modify oxidized phospholipids, which may act as an antagonist of Ca2+-channels. The resulting suppression of Ca2+-signaling inactivates multiple functional NFAT and CREB transcription factors, which may explain H₂ multi-functionality. This review also addresses the involvement of NFAT in the beneficial role of H₂ in COVID-19, Alzheimer's disease and advanced cancer. We discuss some unsolved issues of H₂ action on lipopolysaccharide signaling, MAPK and NF-κB pathways and the Nrf2 paradox. Finally, as a novel idea for the direct targeting of H2, this review introduces the possibility that H₂ causes structural changes in proteins via hydrate water changes.

Hydrogen Gas: A Novel Type of Antioxidant in Modulating Sexual Organs Homeostasis

Sex is a science of cutting edge but bathed in mystery. Coitus or sexual intercourse, which is at the core of sexual activities, requires healthy and functioning vessels to supply the pelvic region, thus contributing to clitoris erection and vaginal lubrication in female and penile erection in male. It is well known that nitric oxide (NO) is the main gas mediator of penile and clitoris erection. In addition, the lightest and diffusible gas molecule hydrogen (H2) has been shown to improve erectile dysfunction (ED), testis injuries, sperm motility in male, preserve ovarian function, protect against uterine inflammation, preeclampsia, and breast cancer in female. Mechanistically, H2 has strong abilities to attenuate excessive oxidative stress by selectively reducing cytotoxic oxygen radicals, modulate immunity and inflammation, and inhibit injuries-induced cell death. Therefore, H2 is a novel bioactive gas molecule involved in modulating sexual organs homeostasis.

Cinnamtannin B-1 Prevents Ovariectomy-Induced Osteoporosis via Attenuating Osteoclastogenesis and ROS Generation

Osteoporosis (OP) is one of the common bone metabolic diseases that endangers postmenopausal women and the elders. Both excessive bone resorption caused by osteoclast over-activation and increased oxidative stress are associated with osteoporosis. Cinnamtannin B-1 (CB-1) is considered as a high-valued plant extract monomer due to its antioxidant properties. However, the mechanism of CB-1 impacts on reducing oxidative stress, inhibiting the production of reactive oxygen species (ROS) and osteoclast differentiation and preventing ovariectomy-induced osteoporosis are still unclear. In this study, the effects of CB-1 on nuclear factor κB (RANKL)-induced osteoclasts formation and differentiation in vitro and the potential therapeutic effect on ovariectomy (OVX)-induced osteoporosis in vivo are investigated. CB-1 was found to inhibit osteoclast formation and bone resorption function in a dose-dependent manner, and it inhibited specific genes related to osteoclast as well. Micro-CT and histopathological staining showed that CB-1 can effectively prevent OVX-induced osteoporosis. In addition, CB-1 treatment can effectively inhibit the production of reactive oxygen species (ROS) in vivo and in vitro. Mechanistically, CB-1 inhibits the activation of osteoclasts by inhibiting the activation of the NF-κB signaling pathway. In conclusion, CB-1 would be able to be used as a promising new drug strategy to inhibit RANKL-induced osteoclastogenesis and prevent ovariectomy-induced osteoporosis.