Nicotinamide mononucleotide alleviates Aluminum induced bone loss by inhibiting the TXNIP-NLRP3 inflammasome

Nicotinamide mononucleotide improves the ovarian reserve of POI by inhibiting NLRP3-mediated pyroptosis of ovarian granulosa cells

BACKGROUND

Premature ovarian insufficiency (POI) is a common clinical problem, but there is currently no effective treatment. NLRP3 inflammasome-induced pyroptosis is thought to be a possible mechanism of POI. Nicotinamide mononucleotide (NMN) has a certain anti-inflammatory effect, providing a promising approach for the treatment of POI.

METHODS

Thirty female Sprague Dawley rats were randomly divided into a control group (n = 10) and a POI group (n = 20). Cyclophosphamide (CTX) was administered for 2 weeks to induce POI. Then the POI group was divided into two groups: the CTX-POI group (n = 10), which was given saline; and the CTX-POI + NMN group (n = 10), which was given NMN at a dose of 500 mg/kg/day for 21 consecutive days. At the end of the study, the serum hormone concentrations of each group were determined, and each group was subjected to biochemical, histopathological, and immunohistochemical analyses. In the in vitro experiment, cell pyroptosis was simulated by using lipopolysaccharide (LPS) and nigricin (Nig), and then KGN cells were treated with NMN, MCC950, and AGK2, and the levels of Nicotinamide adenine dinucleotide (NAD+) and inflammatory factors Interleukin-18(IL-18) and Interleukin-1β(IL-1β) in the cell supernatants were detected, and the levels of pyroptosis-related factors in the cells were determined.

RESULTS

In POI rats, NMN treatments can improve blood hormone levels and partially improve the number of follicles, enhance ovarian reserve function and ovarian index.The evidence is that the increase in NAD+ levels and the activation of SIRT2 expression can reduce the expression of NLRP3, Gasdermin D (GSDMD), Caspase-1, IL-18, and IL-1β in the ovary.

CONCLUSION

NMN improves CTX-induced POI by inhibiting NLRP3-mediated pyroptosis, providing a new therapeutic strategy and drug target for clinical POI patients.

Effect of nicotinamide mononucleotide on osteogenesis in MC3T3-E1 cells against inflammation-induced by lipopolysaccharide

OBJECTIVE

Nicotinamide mononucleotide (NMN) is extensively utilized as an anti-aging agent and possesses anti-inflammatory properties. Lipopolysaccharide (LPS) activates Toll-like receptor 4, a process modulated by intracellular signaling pathways such as the Wnt/β-catenin pathway. This study investigated the impact of NMN on osteogenesis in the presence of LPS.

METHODS

To elucidate the role of NMN in osteogenesis in the context of Gram-negative bacterial infection after LPS treatment, we cultured a mouse pre-osteoblast cell line (MC3T3-E1) and subsequently incubated it with NMN and/or LPS. We then evaluated osteogenic activity by measuring alkaline phosphatase activity, assessing gene expression and protein levels, and performing Alizarin Red S staining and immunocytochemistry.

RESULTS

MC3T3-E1 cells underwent successful differentiation into osteoblasts following treatment with osteogenic induction medium. LPS diminished features related to osteogenic differentiation, which were subsequently partially reversed by treatment with NMN. The restorative effects of NMN on LPS-exposed MC3T3-E1 cells were further substantiated by elucidating the role of Wnt/β-catenin signaling, as confirmed through immunocytochemistry.

CONCLUSION

This study showed that infection with Gram-negative bacteria disrupted the osteogenic differentiation of MC3T3-E1 cells. This adverse effect was partially reversed by administering a high-dose of NMN. Drawing on these results, we propose that NMN could serve as a viable therapeutic strategy to preserve bone homeostasis in elderly and immunocompromised patients.

TXNIP mediated by EZH2 regulated osteogenic differentiation in hBmscs and MC3T3-E1 cells through the modulation of oxidative stress and PI3K/AKT/Nrf2 pathway

BACKGROUND

Previous research has identified a significant role of Thioredoxin-interacting protein (TXNIP) in bone loss. The purpose of this investigation was to assess the role and the underlying molecular mechanisms of TXNIP in the osteogenic differentiation of human bone marrow stromal cells (hBMSCs) and pre-osteoblast MC3T3-E1 cells.

METHODS

Human bone marrow stem cells (hBMSCs) and MC3T3-E1 cells were used to induce osteogenic differentiation. The expression of genes and proteins was assessed using RT-qPCR and western blot, respectively. ChIP assay was used to validate the interaction between genes. The osteogenic differentiation ability of cells was reflected using ALP staining and detection of ALP activity. The mineralization ability of cells was assessed using ARS staining. DCFCA staining was employed to evaluate the intracellular ROS level.

RESULTS

Initially, downregulation of TXNIP and upregulation of EZH2 were observed during osteogenesis in hBMSCs and MC3T3-E1 cells. Additionally, it was discovered that EZH2 negatively regulates TXNIP expression in these cells. Furthermore, experiments indicated that the knockdown of TXNIP stimulated the activation of the PI3K/AKT/Nrf2 signaling pathway in hBMSCs and MC3T3- E1 cells, thus inhibiting the production of reactive oxygen species (ROS). Further functional experiments revealed that overexpression of TXNIP inhibited the osteogenic differentiation in hBMSCs and MC3T3-E1 cells by enhancing ROS produc-tion. On the other hand, knockdown of TXNIP promoted the osteogenic differentiation capacity of hBMSCs and MC3T3-E1 cells through the activation of the PI3K/AKT/Nrf2 pathway.

CONCLUSION

In conclusion, this study demonstrated that TXNIP expression, under the regulation of EZH2, plays a crucial role in the osteogenic differentiation of hBMSCs and MC3T3-E1 cells by regulating ROS production and the PI3K/AKT/Nrf2 pathway.

Metabolic pathways in immune senescence and inflammaging: Novel therapeutic strategy for chronic inflammatory lung diseases. An EAACI position paper from the Task Force for Immunopharmacology

The accumulation of senescent cells drives inflammaging and increases morbidity of chronic inflammatory lung diseases. Immune responses are built upon dynamic changes in cell metabolism that supply energy and substrates for cell proliferation, differentiation, and activation. Metabolic changes imposed by environmental stress and inflammation on immune cells and tissue microenvironment are thus chiefly involved in the pathophysiology of allergic and other immune-driven diseases. Altered cell metabolism is also a hallmark of cell senescence, a condition characterized by loss of proliferative activity in cells that remain metabolically active. Accelerated senescence can be triggered by acute or chronic stress and inflammatory responses. In contrast, replicative senescence occurs as part of the physiological aging process and has protective roles in cancer surveillance and wound healing. Importantly, cell senescence can also change or hamper response to diverse therapeutic treatments. Understanding the metabolic pathways of senescence in immune and structural cells is therefore critical to detect, prevent, or revert detrimental aspects of senescence-related immunopathology, by developing specific diagnostics and targeted therapies. In this paper, we review the main changes and metabolic alterations occurring in senescent immune cells (macrophages, B cells, T cells). Subsequently, we present the metabolic footprints described in translational studies in patients with chronic asthma and chronic obstructive pulmonary disease (COPD), and review the ongoing preclinical studies and clinical trials of therapeutic approaches aiming at targeting metabolic pathways to antagonize pathological senescence. Because this is a recently emerging field in allergy and clinical immunology, a better understanding of the metabolic profile of the complex landscape of cell senescence is needed. The progress achieved so far is already providing opportunities for new therapies, as well as for strategies aimed at disease prevention and supporting healthy aging.

Thioredoxin (Trx): A redox target and modulator of cellular senescence and aging-related diseases

Thioredoxin (Trx) is a compact redox-regulatory protein that modulates cellular redox state by reducing oxidized proteins. Trx exhibits dual functionality as an antioxidant and a cofactor for diverse enzymes and transcription factors, thereby exerting influence over their activity and function. Trx has emerged as a pivotal biomarker for various diseases, particularly those associated with oxidative stress, inflammation, and aging. Recent clinical investigations have underscored the significance of Trx in disease diagnosis, treatment, and mechanistic elucidation. Despite its paramount importance, the intricate interplay between Trx and cellular senescence-a condition characterized by irreversible growth arrest induced by multiple aging stimuli-remains inadequately understood. In this review, our objective is to present a comprehensive and up-to-date overview of the structure and function of Trx, its involvement in redox signaling pathways and cellular senescence, its association with aging and age-related diseases, as well as its potential as a therapeutic target. Our review aims to elucidate the novel and extensive role of Trx in senescence while highlighting its implications for aging and age-related diseases.

The Safety and Antiaging Effects of Nicotinamide Mononucleotide in Human Clinical Trials: an Update

The importance of nicotinamide adenine dinucleotide (NAD+) in human physiology is well recognized. As the NAD+ concentration in human skin, blood, liver, muscle, and brain are thought to decrease with age, finding ways to increase NAD+ status could possibly influence the aging process and associated metabolic sequelae. Nicotinamide mononucleotide (NMN) is a precursor for NAD+ biosynthesis, and in vitro/in vivo studies have demonstrated that NMN supplementation increases NAD+ concentration and could mitigate aging-related disorders such as oxidative stress, DNA damage, neurodegeneration, and inflammatory responses. The promotion of NMN as an antiaging health supplement has gained popularity due to such findings; however, since most studies evaluating the effects of NMN have been conducted in cell or animal models, a concern remains regarding the safety and physiological effects of NMN supplementation in the human population. Nonetheless, a dozen human clinical trials with NMN supplementation are currently underway. This review summarizes the current progress of these trials and NMN/NAD+ biology to clarify the potential effects of NMN supplementation and to shed light on future study directions.

Protective impact of nicotinamide mononucleotide (NMN) and platelet-rich fibrin (PRF) on replicative and radiation-induced senescence of human osteoblasts

The aim of this study was to investigate the cellular changes induced by spontaneous/replicative senescence and radiation in human osteoblasts (OBs), and the impact of cultivation with nicotinamide mononucleotide (NMN) and platelet-rich fibrin (PRF) on apoptosis, senescence-associated β-galactosidase staining (SA β-gal), and senescence-related gene expression using RT2 Profiler PCR array. The results showed that replicative OB aging follows a different pattern from that of radiation-induced cellular senescence. SA β-gal intensity score showed a significant elevation after spontaneous replicative aging of OB (agiT1) 7 days following the start of the experiment, compared with their initial control condition (T0) (T0 = 2.1 ± 0.47; agiT1 = 9.60 ± 1.56; p = 0.001). Concurrent treatment by NMN and PRF showed a protective effect on OBs undergoing replicative senescence, and reduced SA β-gal staining significantly (agiT1 = 9.60 ± 1.56; agiT1+PRF = 3.19 ± 0.52; agiT1+NMN = 3.38 ± 0.36; p < 0.001). These results provide evidence for the potential clinical implications of systematic NMN administration and local PRF application to prevent age-related bone disturbances in elderly patients.

Nicotinamide mononucleotide supplementation mitigates osteopenia induced by modeled microgravity in rats

Exposure to weightlessness causes severe osteopenia, resulting in raised fracture risk. The current study aimed to investigate whether nicotinamide mononucleotide (NMN) supplementation protected against the osteopenia in hindlimb unloading (HLU) rats in vivo and modeled microgravity-induced osteoblastic dysfunction in vitro. The 3-mo-old rats were exposed to HLU and intragastrically administered NMN every 3 days (500 mg/kg body weight) for 4 weeks. NMN supplementation mitigated HLU-induced bone loss, evidenced by greater bone mass and biomechanical properties and better trabecular bone structure. NMN supplementation mitigated HLU-induced oxidative stress, evidenced by greater levels of nicotinamide adenine dinucleotide and activities of superoxide dismutase 2 and lesser malondialdehyde levels. Modeled microgravity stimulation using rotary wall vessel bioreactor in MC3T3-E1 cells inhibited osteoblast differentiation, which was reversed by NMN treatment. Furthermore, NMN treatment mitigated microgravity-induced mitochondrial impairments, evidenced by lesser reactive oxygen species generation and greater adenosine triphosphate production, mtDNA copy number, and activities of superoxide dismutase 2 and Complex I and II. Additionally, NMN promoted activation of AMP-activated protein kinase (AMPK), evidenced by greater AMPKα phosphorylation. Our research suggested that NMN supplementation attenuated osteoblastic mitochondrial impairment and mitigated osteopenia induced by modeled microgravity.

Necroptosis and NLPR3 inflammasome activation mediated by ROS/JNK pathway participate in AlCl3-induced kidney damage

Aluminum (Al) is a common environmental pollutant that can induce kidney damage. However, the mechanism is not clear. In the present study, to explored the exact mechanism of AlCl₃-induced nephrotoxicity, C57BL/6 N male mice and HK-2 cells were used as experimental subjects. Our results showed that Al induced reactive oxygen species (ROS) overproduction, c-Jun N-terminal kinase (JNK) signaling activation, RIPK3-dependent necroptosis, NLRP3 inflammasome activation, and kidney damage. In addition, inhibiting JNK signaling could downregulate the protein expressions of necroptosis and NLRP3 inflammasome, thereby alleviating kidney damage. Meanwhile, clearing ROS effectively inhibited JNK signaling activation, which in turn inhibited necroptosis and NLRP3 inflammasome activation, ultimately alleviating kidney damage. In conclusion, these findings suggest that necroptosis and NLPR3 inflammasome activation mediated by ROS/JNK pathway participate in AlCl₃-induced kidney damage.

Aqueous extract of bay leaf (Laurus nobilis) ameliorates testicular toxicity induced by aluminum chloride in rats

Background and Aim

Human exposure to aluminum is inevitable, and one of the most adverse health effects of aluminum is a decrease in male fertility rates. Therefore, this study investigated the ameliorative effects of an aqueous extract from Laurus nobilis-bay leaf (BL) on aluminum chloride (AlCl₃)-induced testicular toxicity in rats.

Materials and Methods

Twenty-four Wistar rats were divided into four groups (n = 6, each group): The control (group 1) received normal saline; Group 2 animals were intraperitoneally administered with 30 mg/kg body weight (BW) AlCl₃; and Groups 3 and 4 were co-administered AlCl₃ with 125 or 250 mg/kg BW of BL extract, respectively, for 21 days. Testes, epididymis, and blood samples were collected. Testicular plasma enzyme activity was measured using a spectrophotometric assay, while concentrations of inflammatory biomarkers were determined using enzyme-linked immunosorbent assay kits.

Results

There was a significant increase (p < 0.05) in testicular enzyme activity in the group treated with AlCl₃. However, there was no significant (p > 0.05) difference in testicular enzyme activity in groups co-administered AlCl₃ and BL extract as compared with that in control. There was a significant (p < 0.05) increase in testicular nitrite concentration in the AlCl₃-treated group, whereas the administration of BL extract significantly (p < 0.05) decreased nitrite concentration in Groups 3 and 4. Furthermore, the administration of BL extracts increased sperm count and improved the morphology of the testes in AlCl₃-treated rats. Flavonoids, phenolic compounds, alkaloids, tannin, glycosides, saponin, anthraquinones, and steroids were identified in BL extract, with alkaloids and glycosides being the most abundant.

Conclusion

Aqueous extract from BL ameliorated the toxic effect of AlCl₃ and exhibited anti-inflammatory properties by inhibiting nitrite production while improving sperm count and morphology in AlCl₃-treated rats. The bioactivity of the extract may be attributed to the presence of a wide range of phytochemicals. Therefore, BL aqueous extract could be a promising source of novel compounds with male fertility-promoting and anti-inflammatory properties.

Thioredoxin-interacting protein: A new therapeutic target in bone metabolism disorders?

Target identification is essential for developing novel therapeutic strategies in diseases. Thioredoxin-interacting protein (TXNIP), also known as thioredoxin-binding protein-2, is a member of the α-arrestin protein family and is regulated by several cellular stress factors. TXNIP overexpression coupled with thioredoxin inhibits its antioxidant functions, thereby increasing oxidative stress. TXNIP is directly involved in inflammatory activation by interacting with Nod-like receptor protein 3 inflammasome. Bone metabolic disorders are associated with aging, oxidative stress, and inflammation. They are characterized by an imbalance between bone formation involving osteoblasts and bone resorption by osteoclasts, and by chondrocyte destruction. The role of TXNIP in bone metabolic diseases has been extensively investigated. Here, we discuss the roles of TXNIP in the regulatory mechanisms of transcription and protein levels and summarize its involvement in bone metabolic disorders such as osteoporosis, osteoarthritis, and rheumatoid arthritis. TXNIP is expressed in osteoblasts, osteoclasts, and chondrocytes and affects the differentiation and functioning of skeletal cells through both redox-dependent and -independent regulatory mechanisms. Therefore, TXNIP is a potential regulatory and functional factor in bone metabolism and a possible new target for the treatment of bone metabolism-related diseases.

Solid-state 1H NMR-based metabolomics assessment of tributylin effects in zebrafish bone

Tributyltin (TBT), an endocrine disruptor is used globally in agribusiness and industries as biocides, heat stabilizers, and in chemical catalysis. It is known for its deleterious effects on bone by negatively impacting the functions of osteoblasts, osteoclasts and mesenchymal stem cells. However, the impact of TBT on the metabolomics profile in bone is not yet studied. Here, we demonstrate alterations in chemical metabolomics profiles measured by solid state ¹H nuclear magnetic resonance (¹H NMR) spectroscopy in zebrafish bone following tributyltin (TBT) treatment. TBT of 0, 100, 200, 300, 400 and 500 μg/L were exposed to zebrafish. From this, zebrafish bone has subjected for further metabolomics profiling. Samples were measured via one-dimensional (1D) solvent -suppressed and T₂- filtered methods with in vivo zebrafish metabolites. A dose dependent alteration in the metabolomics profile was observed and results indicated a disturbed aminoacid metabolism, TCA cycle, and glycolysis. We found a significant alteration in the levels of glutamate, glutamine, glutathione, trimethylamine N-oxide (TMAO), and other metabolites. This investigation hints us the deleterious effects of TBT on zebrafish bone enabling a comprehensive understanding of metabolomics profile and is expected to play a crucial role in understanding the deleterious effects of various endocrine disruptor on bone.

Aging Leukocytes and the Inflammatory Microenvironment of the Adipose Tissue

Age-related immunosenescence, defined as an increase in inflammaging and the decline of the immune system, leads to tissue dysfunction and increased risk for metabolic disease. The elderly population is expanding, leading to a heightened need for therapeutics to improve health span. With age, many alterations of the immune system are observed, including shifts in the tissue-resident immune cells, increased expression of inflammatory factors, and the accumulation of senescent cells, all of which are responsible for a chronic inflammatory loop. Adipose tissue and the immune cell activation within are of particular interest for their well-known roles in metabolic disease. Recent literature reveals that adipose tissue is an organ in which signs of initial aging occur, including immune cell activation. Aged adipose tissue reveals changes in many innate and adaptive immune cell subsets, revealing a complex interaction that contributes to inflammation, increased senescence, impaired catecholamine-induced lipolysis, and impaired insulin sensitivity. Here, we will describe current knowledge surrounding age-related changes in immune cells while relating those findings to recent discoveries regarding immune cells in aged adipose tissue.

Polarization of rheumatoid macrophages is regulated by the CDKN2B-AS1/ MIR497/TXNIP axis

The polarization of macrophages plays a critical role in the pathophysiology of rheumatoid arthritis. The macrophages can have pro-inflammatory M1 polarization and various types of alternative anti-inflammatory M2 polarization. Our preliminary results showed that the CDKN2B-AS1/MIR497/TXNIP axis might regulate macrophages of rheumatoid arthritis patients. Therefore, we hypothesized that this axis regulated the polarization of rheumatoid macrophages. Flow cytometry was used to determine the surface polarization markers in M1 or M2 macrophages from healthy donors and rheumatoid arthritis patients. The QPCR and Western Blotting were used to compare the expression of the CDKN2B-AS1/MIR497/TXNIP axis in these macrophages. We Knocked down and overexpressed the axis in the macrophage cell line MD to test its roles in macrophage polarization. Compared to cells from healthy donors, cells from rheumatoid arthritis patients expressed higher levels of CD40 and CD80 and lower levels of CD16, CD163, CD206, and CD200R after polarization, they also expressed higher CDKN2B-AS1, lower MIR497, and higher TXNIP. In macrophages from healthy donors, there was no correlation among CDKN2B-AS1, MIR497, and TXNIP. But in macrophages from patients, there were significant correlations. The CDKN2B-AS1 knockdown, MIR497 mimics suppressed the M1 polarization but promoted the M2 polarization in MD cells, while the MIR497 knockdown and the TXNIP overexpression did the opposite. This study demonstrated that elevated CDKN2B-AS1 in macrophages promotes the M1 polarization and inhibited the M2 polarization of macrophages by the CDKN2B-AS1/ MIR497/TXNIP axis.

Mitophagy and apoptosis mediated by ROS participate in AlCl3-induced MC3T3-E1 cell dysfunction

Aluminum (Al), as a common environmental pollutant, causes osteoblast (OB) dysfunction and then leads to Al-related bone diseases (ARBD). One of the mechanisms of ARBD is oxidative stress, which leads to an increase in the production of reactive oxygen species (ROS). ROS can induce mitochondrial damage, thereby inducing mitophagy and apoptosis. But whether mitophagy and apoptosis mediated by ROS, and the role of ROS in AlCl₃-induced MC3T3-E1 cell dysfunction is still unclear. In this study, MC3T3-E1 cells used 0 mM Al (control group), 2 mM Al (Al group), 5 mM N-acetyl cysteine (NAC) (NAC group), 2 mM Al and 5 mM NAC (Al + NAC group) for 24 h. We found AlCl₃-induced MC3T3-E1 cell dysfunction accompanied by oxidative stress, apoptosis, and mitophagy. While NAC, a ROS scavenger treatment, restored cell function and alleviated the mitophagy and apoptosis. These results suggested that mitophagy and apoptosis mediated by ROS participate in AlCl₃-induced MC3T3-E1 cell dysfunction.

NLRP3 Inflammasome: A Promising Therapeutic Target for Drug-Induced Toxicity

Drug-induced toxicity, which impairs human organ function, is a serious problem during drug development that hinders the clinical use of many marketed drugs, and the underlying mechanisms are complicated. As a sensor of infections and external stimuli, nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a key role in the pathological process of various diseases. In this review, we specifically focused on the role of NLRP3 inflammasome in drug-induced diverse organ toxicities, especially the hepatotoxicity, nephrotoxicity, and cardiotoxicity. NLRP3 inflammasome is involved in the initiation and deterioration of drug-induced toxicity through multiple signaling pathways. Therapeutic strategies via inhibiting NLRP3 inflammasome for drug-induced toxicity have made significant progress, especially in the protective effects of the phytochemicals. Growing evidence collected in this review indicates that NLRP3 is a promising therapeutic target for drug-induced toxicity.

Intersection of immunometabolism and immunosenescence during aging

Aging is associated with the highest risk for morbidity and mortality to chronic or metabolic diseases, which are present in 50% of the elderly. Improving metabolic and immune function of the elderly would improve quality of life and reduce the risk for all other diseases. Tissue-resident macrophages and the NLRP3 inflammasome are established drivers of inflammaging and metabolic dysfunction. Energy-sensing signaling pathways connect sterile and metabolic inflammation with cellular senescence and tissue dysfunction. We discuss recent advances in the immunometabolism field. Common themes revealed by recent publications include the alterations in metabolic signaling (SIRTUIN, AMPK, or mTOR pathways) in aged immune cells, the impact of senescence on inflammaging and tissue dysfunction, and the age-related changes in metabolic tissues, especially adipose tissue, as an immunological organ. Promising gerotherapeutics are candidates to broadly target nutrient and energy sensing, inflammatory and senescence pathways, and have potential to improve healthspan and treat age-related diseases.

Long non-coding RNA MEG3 silencing and microRNA-214 restoration elevate osteoprotegerin expression to ameliorate osteoporosis by limiting TXNIP

Studies have shown that long non-coding RNA (lncRNA) MEG3 plays a key role in osteoporosis (OP), but its regulatory mechanism is somewhat incompletely clear. Here, we intend to probe into the mechanism of MEG3 on OP development by modulating microRNA-214 (miR-214) and thioredoxin-interacting protein (TXNIP). Rat models of OP were established. MEG3, miR-214 and TXNIP mRNA expression in rat femoral tissues were detected, along with TXNIP, OPG and RANKL protein expression. BMD, BV/TV, Tb.N and Tb.Th in tissue samples were measured. Ca, P and ALP contents in rat serum were also determined. Primary osteoblasts were isolated and cultured. Viability, COL-I, COL-II and COL-Χ mRNA expression, PCNA, cyclin D1, OCN, RUNX2 and osteolix protein expresion, ALP content and activity, and mineralized nodule area of rat osteoblasts were further detected. Dual-luciferase reporter gene and RNA-pull down assays verified the targeting relationship between MEG3, miR-214 and TXNIP. MEG3 and TXNIP were up-regulated while miR-214 was down-regulated in femoral tissues of OP rats. MEG3 silencing and miR-214 overexpression increased BMD, BV/TV, Tb.N, Tb.Th, trabecular bone area, collagen area and OPG expression, and down-regulated RANKL of femoral tissues in OP rats. MEG3 silencing and miR-214 overexpression elevated Ca and P and reduced ALP in OP rat serum, elevated osteoblast viability, differentiation ability, COL-I and COL-Χ expression and ALP activity, and reduced COL-II expression of osteoblasts. MEG3 specifically bound to miR-214 to regulate TXNIP. MEG3 silencing and miR-214 overexpression promote proliferation and differentiation of osteoblasts in OP by down-regulating TXNIP, which further improves OP.

The protective effect of esculetin against aluminium chloride-induced reproductive toxicity in rats

One of the prominent health problems caused by Aluminium was the decrease in male fertility rates. In the study, the protective effect of Esculetin (ESC) against the reproductive toxicity induced by Aluminium chloride (AlCl₃ ) was investigated. For this purpose, AlCl₃ was administrated to Wistar Albino rats at a dose of 34 mg/kg and ESC was administrated at a dose of 50 mg/kg for 70 days. It was determined that AlCl₃ treatment reduced sperm motility and concentration, increased dead/live rate and abnormal sperm rate. It decreased serum testosterone level, and co-treatment of ESC significantly regulated these values. In the AlCl₃ -treated group, MDA level increased and GSH level, GPx and CAT activities decreased compared with those of the control group. However, co-treatment of ESC showed an amelioratory effect on the values except for CAT activity. It was observed that the expression level of NRF-2 increased in the ESC and AlCl₃  + ESC groups, and NF-κB increased in the AlCl₃ group with the control group. It was determined that Caspase-3 expression decreased, and Bcl-2 expression increased in AlCl₃  + ESC group compared to AlCl₃ group. It was also determined that AlCl₃ -induced tissue injury was significantly prevented by ESC co-treatment.

The Role of NLRP3 Inflammasome Activities in Bone Diseases and Vascular Calcification

Continuous stimulation of inflammation is harmful to tissues of an organism. Inflammatory mediators not only have an effect on metabolic and inflammatory bone diseases but also have an adverse effect on certain genetic and periodontal diseases associated with bone destruction. Inflammatory factors promote vascular calcification in various diseases. Vascular calcification is a pathological process similar to bone development, and vascular diseases play an important role in the loss of bone homeostasis. The NLRP3 inflammasome is an essential component of the natural immune system. It can recognize pathogen-related molecular patterns or host-derived dangerous signaling molecules, recruit, and activate the pro-inflammatory protease caspase-1. Activated caspase-1 cleaves the precursors of IL-1β and IL-18 to produce corresponding mature cytokines or recognizes and cleaves GSDMD to mediate cell pyroptosis. In this review, we discuss the role of NLRP3 inflammasome in bone diseases and vascular calcification caused by sterile or non-sterile inflammation and explore potential treatments to prevent bone loss.

Melatonin Attenuates AlCl3-Induced Apoptosis and Osteoblastic Differentiation Suppression by Inhibiting Oxidative Stress in MC3T3-E1 Cells

Aluminum (Al) inhibits osteoblast-mediated bone formation by oxidative stress, resulting in Al-induced bone disease. Melatonin (MT) has received extensive attention due to its antioxidant and maintenance of bone health effect. To evaluate the protective effect and mechanism of MT on AlCl₃-induced osteoblast dysfunction, MC3T3-E1 cells were treated with MT (100 μM) and/or AlCl₃ (8 μM). First, MT alleviated AlCl₃-induced osteoblast dysfunction, presenting as the reduced apoptosis rate as well as increased cell viability, alkaline phosphatase (ALP) activity, and type I collagen (COL-1) level. Then, MT significantly attenuated AlCl₃-induced oxidative stress, presenting as the reduced reactive oxygen species and 8-hydroxy-2'-deoxyguanosine levels as well as increased glutathione level and superoxide dismutase activity. Finally, MT protected MC3T3-E1 cells against p53-dependent apoptosis and differentiation suppression, as assessed by Caspase-3 activity, protein levels of p53, Bcl-2-associated X protein (Bax), B cell lymphoma gene 2 (Bcl-2), cytosolic Cytochrome c, Runt-related transcription factor 2 (Runx2), and Osterix, as well as the mRNA levels of Bax, Bcl-2, Runx2, Osterix, ALP, and COL-1. Overall, our findings demonstrate MT attenuates AlCl₃-induced apoptosis and osteoblastic differentiation suppression by inhibiting oxidative stress in MC3T3-E1 cells.

Nicotinamide mononucleotide attenuates glucocorticoid‑induced osteogenic inhibition by regulating the SIRT1/PGC‑1α signaling pathway

Long-term and high-dose glucocorticoid treatment is recognized as an important influencing factor for osteoporosis and osteonecrosis. Nicotinamide mononucleotide (NMN) is an intermediate of NAD⁺ biosynthesis, and is widely used to replenish the levels of NAD⁺. However, the potential role of NMN in glucocorticoid-induced osteogenic inhibition remains to be demonstrated. In the present study, the protective effects of NMN on dexamethasone (Dex)-induced osteogenic inhibition, and its underlying mechanisms, were investigated. Bone mesenchymal stem cells were treated with Dex, which decreased the levels of the osteogenic markers alkaline phosphatase, Runt-related transcription factor 2 and osteocalcin. NMN treatment attenuated Dex-induced osteogenic inhibition and promoted the expression of sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α. SIRT1 knockdown reversed the protective effects of NMN and reduced the expression levels of PGC-1α. Collectively, the results of the present study reveal that NMN may be a potential therapeutic target for glucocorticoid-induced osteoporosis.

Nicotinamide Mononucleotide: A Promising Molecule for Therapy of Diverse Diseases by Targeting NAD+ Metabolism

NAD+, a co-enzyme involved in a great deal of biochemical reactions, has been found to be a network node of diverse biological processes. In mammalian cells, NAD+ is synthetized, predominantly through NMN, to replenish the consumption by NADase participating in physiologic processes including DNA repair, metabolism, and cell death. Correspondingly, aberrant NAD+ metabolism is observed in many diseases. In this review, we discuss how the homeostasis of NAD+ is maintained in healthy condition and provide several age-related pathological examples related with NAD+ unbalance. The sirtuins family, whose functions are NAD-dependent, is also reviewed. Administration of NMN surprisingly demonstrated amelioration of the pathological conditions in some age-related disease mouse models. Further clinical trials have been launched to investigate the safety and benefits of NMN. The NAD+ production and consumption pathways including NMN are essential for more precise understanding and therapy of age-related pathological processes such as diabetes, ischemia–reperfusion injury, heart failure, Alzheimer’s disease, and retinal degeneration.