A clinical-stage Nrf2 activator suppresses osteoclast differentiation via the iron-ornithine axis

Vaccarin ameliorates osteoarthritis by suppressing the c-Jun N-terminal kinase (JNK)-serum amyloid A2 (SAA2) pathway mediating chondrocyte senescence

BACKGROUND

Osteoarthritis is a chronic degenerative joint disease marked by chondrocyte senescence and extracellular matrix degradation. Vaccarin, a flavonoid with anti-inflammatory and antioxidant properties, has not been previously investigated for its therapeutic potential in osteoarthritis.

PURPOSE

To evaluate the therapeutic potential of Vaccarin in osteoarthritis and elucidate its underlying mechanisms.

DESIGN AND METHOD

This study utilized in vitro chondrocyte cultures and RNA sequencing to identify relevant pathways, followed by validation at the genetic, protein, and metabolic levels using multiple approaches. Additionally, the therapeutic effects of Vaccarin were assessed in vivo using a destabilization of the medial meniscus (DMM)-induced osteoarthritis mouse model and human cartilage samples from osteoarthritis patients.

RESULTS

Vaccarin effectively ameliorated osteoarthritis both in vivo and in vitro. Transcriptomic sequencing indicated a significant downregulation of serum amyloid A2 (SAA2) expression following Vaccarin treatment. Multi-omics analysis, validated by human specimens, indicated that SAA2 is minimally secreted in healthy articular cartilage but serves as a crucial osteoarthritis biomarker in Asian populations. Mechanistically, Vaccarin inhibits c-Jun N-terminal kinase (JNK) phosphorylation, thereby reducing SAA2 expression and mitigating chondrocyte inflammation and senescence. Notably, inflammatory conditions upregulate SAA2 expression in chondrocytes via the JNK pathway. Elevated SAA2 levels contribute to mitochondrial dysfunction in chondrocytes, leading to increased reactive oxygen species (ROS) production and exacerbating osteoarthritis progression.

CONCLUSION

This study identifies SAA2 as a potential therapeutic target for osteoarthritis and suggests that Vaccarin presents a promising treatment avenue.

Engineered Spirulina platensis for treating rheumatoid arthritis and restoring bone homeostasis

Rheumatoid arthritis (RA) is characterized by massive intra-articular infiltration of pro-inflammatory macrophages, leading to articular immune dysfunction, severe synovitis, and ultimately joint erosion. Comprehensive remodeling of articular immune homeostasis and bone homeostasis is essential for alleviating RA. Here we report on Spirulina platensis (SP), a natural microorganism commercially farmed worldwide as a food, as an efficient regulator of both synovial inflammation and osteoclast differentiation in male RA mouse models. SP reduces excessive reactive oxygen species and downregulates pro-inflammatory cytokines in synovial macrophages. Moreover, SP reprograms pro-inflammatory M1-like macrophages to anti-inflammatory M2-like phenotype, suppressing synovitis and remodeling redox balance. Notably, SP inhibits osteoclast activation effectively and blocks the progression of bone erosion. SP is then engineered with macrophage membranes (SP@M) to enable immune evasion and RA-targeting in vivo. SP@M increases LC3-mediated autophagy as well as strengthens ubiquitin-mediated proteasomal degradation toward KEAP1, which promotes the expression and nuclear translocation of NRF2. The NRF2 further activates antioxidant enzymes to terminate macrophages-initiated pathological cascades and reestablish intra-articular immune homeostasis, conferring a bone recovery and chondroprotective effect in collagen-induced arthritis mouse models. This work shows the therapeutic activity of FDA-approved functional food of SP in suppressing synovial inflammation and osteoclast differentiation, offering an off-the-shelf strategy for RA treatment.

Picropodophyllin induces ferroptosis via blockage of AKT/NRF2/SLC7A11 and AKT/NRF2/SLC40A1 axes in hepatocellular carcinoma as a natural IGF1R inhibitor

BACKGROUND

Ferroptosis represents a distinct form of regulated cell death characterized by intracellular iron overload and extensive lipid peroxidation. Targeting ferroptosis-related signaling pathways and inducing ferroptosis have emerged as promising therapeutic strategies for hepatocellular carcinoma (HCC). Recent studies have highlighted the involvement of insulin-like growth factor 1 receptor (IGF1R) signaling in cancer progression and antioxidant defense mechanisms. Picropodophyllin (PPP), a natural IGF1R inhibitor isolated from Dysosma versipellis, exhibits anticancer effects against several solid tumors. However, the impact of PPP on ferroptosis in HCC and the underlying molecular mechanisms remain unclear.

PURPOSE

The current study aims to evaluate the anti-tumor effects of PPP on HCC progression in vitro and in vivo, and to investigate the actions and mechanisms of PPP as a novel ferroptosis inducer.

METHODS

Clinical sample from HCC patients were applied to analyze the correlation of IGF1R with malignancy of HCC. Docking simulations, molecular dynamics simulation and cellular thermal shift assay were performed to verify the interaction between PPP and IGF1R. CCK-8 cell viability assay, colony formation, Calcein-AM/PI staining, wound healing and transwell assays were conducted to determine the effects of PPP on cell viability, proliferation, migration and invasion. Intracellular Fe2+, GSH, MDA and lipid ROS levels were measured to evaluate the degree of ferroptosis induced by PPP. GO functional annotation and KEGG enrichment analysis, quantitative real-time PCR, western blot and immunofluorescence (IF) assay were performed to investigate the mechanisms underlying the action of PPP. Nude mice xenograft model and immunohistochemistry (IHC) assay were utilized to observe the impact of PPP on tumor growth in vivo.

RESULTS

Upregulation of IGF1R were confirmed to positively correlated with malignant progression of HCC and PPP were verified to act as a specific inhibitor of IGF1R in HCC. PPP exhibited dose-dependent anti-proliferative and anti-metastasis effects on HCC cells, and inhibited HCC growth in a subcutaneous xenograft murine model. Meanwhile, PPP remarkably increased intracellular Fe2+, lipid ROS and MDA levels, but decreased ROS scavenger GSH content and glutathione peroxidase 4 (GPX4) activity significantly, which suggested that PPP stimulated ferroptosis relying on iron-dependent lipid peroxidation. The ferroptosis inhibitor deferoxamine mesylate (DFO) nearly abolished the anti-cancer and ferroptosis-inducing effects of PPP both in vitro and in vivo. Mechanistically, PPP inhibited the phosphorylation of IGF1R, PI3K and AKT, thus suppressed the protein stability of NRF2 by facilitating ubiquitination, and consequently decreased expression of its target gene SLC7A11 and SLC40A1.

CONCLUSION

The natural IGF1R inhibitor PPP induced ferroptosis through blockage of PI3K/AKT/NRF2 signaling pathway and subsequent inhibition of downstream gene expression of SLC7A11 and SLC40A1 in hepatocellular carcinoma. Consequently, our findings provide a novel action and mechanism of PPP, as well as offer innovative and promising ferroptosis-inducing agents for the clinical treatment of HCC.

The foam cell-derived exosomes exacerbate ischemic white matter injury via transmitting metabolic defects to microglia

Atherosclerosis (AS) has been shown to be an independent risk factor for vascular cognitive impairment (VCI), but the mechanisms remain unclear. Here, we found that AS circulating exosomes exacerbated ischemic white matter injury and VCI. Exosomes originating from macrophage-derived foam cells targeted microglia. Mechanistically, foam cell-derived exosomes transmitted redox imbalance, mitochondrial dysfunction, and metabolic defects to microglia via the miR-101-3p-Nrf2-Slc2a1 axis. Anti-miR-101-3p or activation of Nrf2, both genetically and pharmacologically, could antagonize AS exosomes and ameliorate VCI. In conclusion, our findings reveal a distant connection between peripheral macrophages and brain microglia, which provides new insights and potential targets of AS-induced VCI.

The Nrf2-Keap1/ARE signaling pathway in aquatic animals

The complex and fluctuating conditions of aquatic ecosystems make aquatic organisms vulnerable to oxidative stress. The Nrf2-Keap1/ARE signaling pathway serves as an important intracellular defense mechanism, particularly for aquatic organisms exposed to environmental stressors and toxic substances. Environmental stimuli can disrupt an organism's internal redox balance, leading to cellular oxidative stress responses. To counteract these effects, cells develop intricate defense mechanisms, with the Nrf2-Keap1/ARE signaling pathway is playing a crucial role. In this pathway, the nuclear transcription factor Nrf2 translocates into the nucleus to initiate the transcription of antioxidant genes, thereby reducing reactive oxygen species (ROS)-induced cellular damage and maintaining the organism's oxidative-antioxidative equilibrium. While research on this pathway in mammals is well-established, studies on aquatic organisms are still limited. This review provides a comprehensive analysis of the regulatory functions of the Nrf2-Keap1/ARE pathway on oxidative stress and delves into the molecular structures of Nrf2, Keap1, and ARE, offering insights into the physiological regulation of antioxidant defenses in aquatic organisms.

Identification of Food-Derived Electrophilic Chalcones as Nrf2 Activators Using Comprehensive Virtual Screening Techniques

Electrophilic compounds are bioactive components commonly found in foods that are capable of covalently modifying nucleophilic sites on biologically functional macromolecules. These compounds may elicit positive bioactivity or negative biotoxicity, posing significant challenges in terms of time and resource expenditure in the de novo characterization of their biological activity. In this study, we developed a database of 332 food-derived electrophilic compounds and used a semi-supervised k-nearest neighbors (KNN) machine learning model to predict their bioactivity. Molecular docking analysis identified the three chalcone compounds with the highest potential positive activity-4-hydroxyderricin (4HD), isoliquiritigenin (ISO), and butein. Furthermore, in cell experiments, treatment with 4HD, ISO, and butein significantly reduced reactive oxygen species (ROS) levels. An RT-qPCR analysis demonstrated that these chalcones significantly upregulated the mRNA expression of Nrf2 and its downstream antioxidant genes, including Nqo1, HO-1, Gsr, Gclc, and Gclm. ISO's cytoprotective and antioxidant effects were abolished following these findings, which highlight that 4HD, ISO, and butein are effective Nrf2 activators and suggest that comprehensive virtual technology is a promising strategy for identifying functional bioactive compounds.

Nrf2 activators for the treatment of rare iron overload diseases: From bench to bedside

Iron overload and related oxidative damage are seen in many rare diseases, due to mutation of iron homeostasis-related genes. As a core regulator on cellular antioxidant reaction, Nrf2 can also decrease systemic and cellular iron levels by regulating iron-related genes and pathways, making Nrf2 activators very good candidates for the treatment of iron overload disorders. Successful examples include the clinical use of omaveloxolone for Friedreich's Ataxia and dimethyl fumarate for relapsing-remitting multiple sclerosis. Despite these uses, the therapeutic potentials of Nrf2 activators for iron overload disorders may be overlooked in clinical practice. Therefore, this study talks about the potential use, possible mechanisms, and precautions of Nrf2 activators in treating rare iron overload diseases. In addition, a combination therapy with Nrf2 activators and iron chelators is proposed for clinical reference, aiming to facilitate the clinical use of Nrf2 activators for more iron overload disorders.

Patenting perspective on Keap1 inhibitors (2019-2024)

INTRODUCTION

Kelch-like ECH-associated protein 1 (Keap1), an E3 ligase negatively regulating the nuclear factor erythroid 2-related factor 2 (Nrf2), has emerged as an auspicious drug target for treating ailments associated with oxidative stress and inflammation. Discovery of Keap1 inhibitors have attracted significant interest.

AREAS COVERED

This review covers patents on Keap1 inhibitors from 2019 to 2024, providing a comprehensive analysis of their structural characteristics, optimization strategies, pharmacological properties and clinical progress.

EXPERT OPINION

Extensive efforts have been devoted to enhance potency and drug-like properties of Keap1 inhibitors. Strategies such as ROS-cleavable prodrug design, bivalent inhibition and PROTACs are emerging. As the range of drug types and applications expands, Keap1 inhibitors are becoming a sagacious option for disease treating.

Hydroxytyrosol as a Mitochondrial Homeostasis Regulator: Implications in Metabolic Syndrome and Related Diseases

Hydroxytyrosol (HT), a principal bioactive phytochemical abundant in Mediterranean dietary sources, has emerged as a molecule of significant scientific interest owing to its multifaceted health-promoting properties. Accumulating evidence suggests that HT's therapeutic potential in metabolic disorders extends beyond conventional antioxidant capacity to encompass mitochondrial regulatory networks. This review synthesizes contemporary evidence from our systematic investigations and the existing literature to delineate HT's comprehensive modulatory effects on mitochondrial homeostasis. We systematically summarized the impact of HT on mitochondrial dynamics (fusion/fission equilibrium), biogenesis and energy metabolism, mitophagy, inter-organellar communication with the endoplasmic reticulum, and microbiota-mitochondria crosstalk. Through this multidimensional analysis, we established HT as a mitochondrial homeostasis modulator with potential therapeutic applications in metabolic syndrome (MetS) and its related pathologies including type 2 diabetes mellitus, obesity-related metabolic dysfunction, dyslipidemia, non-alcoholic steatohepatitis, and hypertension-related complications. Moreover, we further discussed translational challenges in HT research, emphasizing the imperative for direct target identification, mitochondrial-targeted delivery system development, and combinatorial therapeutic strategies. Collectively, this review provides a mechanistic framework for advancing HT research and accelerating its clinical implementation in MetS and its related diseases.

Emerging Contaminants: An Important But Ignored Risk Factor for Psoriasis

Industrialization and modernization have changed the environment. A group of emerging contaminants (ECs) has been defined recently. Psoriasis, whose incidence has increased in recent years, is a relapsing immune-mediated disease carrying a heavy disease burden. The erythematous scaly plaque is a typical symptom and occurs on several parts of the body. In addition, psoriasis has many comorbidities, such as psoriatic arthritis, diabetes, and depression, damaging the quality of life of patients. IL-17, IL-12, IL-23, and TNF-alpha are important related cytokines. ECs can influence psoriasis through the immune system and inflammatory responses. Specific mechanisms include increasing pro-inflammatory cytokines such as TNF-α and IL-17, and activating immune cells such as macrophages. And for psoriasis patients, it is suggested to reduce the exposure of most ECs. However, the complex mechanisms involved have not been discussed together and concluded. In this review, we summarize the relationship between ECs and psoriasis, focusing on the immune system, especially the immune cells and cytokines. These results can help guide clinical treatment and long-term management of psoriasis.

Quercetagetin alleviates inflammatory osteoclastogenesis and collagen antibody-induced arthritis via Nrf2 signaling and Pten/AKT/Nfatc1 axis

PURPOSE

Quercetagetin, a flavonoid derived from the natural herb Flos eriocauli, is used in traditional Chinese medicine for its fire-purging (anti-inflammation) and wind-expelling (pain-alleviating) properties. However, its potential effects concerning rheumatoid arthritis (RA) remain underexplored. This study was designed to elucidate the potential associations between Quercetagetin and RA, establishing the therapeutic potential of Quercetagetin and related mechanisms in RA treatment.

METHODS

Network pharmacology was conducted to decipher related targets and signaling pathways between Quercetagetin and RA. In vitro assays were then conducted to explore the effects of Quercetagetin on osteoclast cell behaviors and corresponding signaling pathways. In vivo study further validated the therapeutic effect of Quercetagetin in collagen antibody-induced arthritis (CAIA) mice.

RESULTS

The network pharmacological analysis indicated an intimate correlation of Quercetagetin with RA-related inflammatory osteolysis treatment. Pertaining to biological validations, 2 µM of Quercetagetin successfully inhibited LPS-driven osteoclast differentiation and function. qPCR assay and Western blot analyses denoted parallel changes in osteoclastic marker genes and proteins. Further mechanism study uncovered the effect of Quercetagetin in stimulating the Nrf2/Keap1 signaling pathway and moderating the Pten/AKT/Nfatc1 axis in osteoclasts. In vivo study revealed 40 mg/kg Quercetagetin every day could significantly relief joint destruction in CAIA mice.

CONCLUSIONS

Our study presents Quercetagetin 's therapeutic potential in treating RA, outlining its effects and potential mechanisms in suppressing LPS-induced osteoclast activity, and alleviating inflammatory bone destruction in CAIA model, thereby laying the groundwork for further translational research on Quercetagetin and Flos eriocauli in RA treatment.

Redox regulation: mechanisms, biology and therapeutic targets in diseases

Redox signaling acts as a critical mediator in the dynamic interactions between organisms and their external environment, profoundly influencing both the onset and progression of various diseases. Under physiological conditions, oxidative free radicals generated by the mitochondrial oxidative respiratory chain, endoplasmic reticulum, and NADPH oxidases can be effectively neutralized by NRF2-mediated antioxidant responses. These responses elevate the synthesis of superoxide dismutase (SOD), catalase, as well as key molecules like nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), thereby maintaining cellular redox homeostasis. Disruption of this finely tuned equilibrium is closely linked to the pathogenesis of a wide range of diseases. Recent advances have broadened our understanding of the molecular mechanisms underpinning this dysregulation, highlighting the pivotal roles of genomic instability, epigenetic modifications, protein degradation, and metabolic reprogramming. These findings provide a foundation for exploring redox regulation as a mechanistic basis for improving therapeutic strategies. While antioxidant-based therapies have shown early promise in conditions where oxidative stress plays a primary pathological role, their efficacy in diseases characterized by complex, multifactorial etiologies remains controversial. A deeper, context-specific understanding of redox signaling, particularly the roles of redox-sensitive proteins, is critical for designing targeted therapies aimed at re-establishing redox balance. Emerging small molecule inhibitors that target specific cysteine residues in redox-sensitive proteins have demonstrated promising preclinical outcomes, setting the stage for forthcoming clinical trials. In this review, we summarize our current understanding of the intricate relationship between oxidative stress and disease pathogenesis and also discuss how these insights can be leveraged to optimize therapeutic strategies in clinical practice.

TRAF1 promotes osteoclastogenesis by enhancing metabolic adaptation to oxidative phosphorylation in an AKT-dependent manner

Tumor necrosis factor receptor-associated factor 1 (TRAF1) is a crucial signaling adaptor involved in multiple cellular events. However, its role in regulating osteoclastogenesis and energy metabolism remains unclear. Here, we report that TRAF1 promotes osteoclastogenesis and oxidative phosphorylation (OXPHOS). Employing RNA sequencing, we found that TRAF1 is markedly upregulated during osteoclastogenesis and is positively associated with osteoporosis. TRAF1 knockout inhibits osteoclastogenesis and increases bone mass in both normal and ovariectomized adult mice without affecting bone mass in childhood. Furthermore, TRAF1 promotes osteoclast OXPHOS by increasing the phosphorylation level of AKT. Mechanistically, TRAF1 functions to inhibit TRAF2-induced ubiquitination of Gβl, a known activator of AKT, and further upregulates AKT phosphorylation. Rescue experiments revealed that the inhibitory effects of TRAF1 knockout on osteoclastogenesis, OXPHOS, and bone mass are dependent on AKT. Collectively, our findings uncover a previously unrecognized function of TRAF1 in regulating osteoclastogenesis and energy metabolism, and establish a novel TRAF1-AKT-OXPHOS axis in osteoclasts.

WWOX-mediated p53/SAT1 and NRF2/FPN1 axis contribute to toosendanin-induced ferroptosis in hepatocellular carcinoma

Although ferroptosis as an emerging way exhibits tremendous promising in the therapy of hepatocellular carcinoma (HCC), the novel therapeutic agents targeting ferroptosis are still scarce. In our previous study, we found that the natural products toosendanin (TSN) possessed significant anti-proliferative efficacy by regulating WW domain-containing oxidoreductase (WWOX) in HCC. However, there is very limited understanding about TSN-induced ferroptosis, and the role of WWOX in ferroptosis has not been studied. In present study, we investigated the effect and underlying molecular mechanisms of TSN in WWOX-mediated ferroptosis in HCC. We found that TSN induced ferroptosis in HCC cells and its effect was dependent on WWOX. RNA-seq and RT-qPCR assay identified that TSN significantly increased spermidine/spermine N1-acetyltransferase 1 (SAT1) expression while decreased solute carrier family 40 member 1 (SLC40A1) expression, which play vital roles in ferrous ion transport. Further dual-luciferase reporter assay and Co-IP assay revealed that TSN-induced WWOX activation controlled the transcriptional activity of p53 and NF-E2-related factor 2 (NRF2) by regulating their interaction. Meanwhile, IF assay and WB assay confirmed that TSN increased the nuclear distribution of p-WWOX and p-p53 dimers, but impeded the nuclear translocation of NRF2 by inducing its ubiquitination degradation, ultimately regulating the transcription of their downstream target genes. In addition, the results from cell viability assay and the tumor xenograft model verified that co-treatment of TSN, ML385 (NRF2 inhibitor), and MIRA-1 (p53 activator) could effectively inhibit HCC cells growth in the presence of Fer-1 (ferroptosis inhibitor) in vitro and in vivo. Overall, our study contributes to the necessary understanding of the molecular mechanisms of WWOX-mediated ferroptosis regulation, and identifies TSN as a potential therapeutic agent targeting ferroptosis for HCC.

Microglial Nrf2-mediated lipid and iron metabolism reprogramming promotes remyelination during white matter ischemia

BACKGROUND

Oxidative stress and microglial activation are critical pathomechanisms in ischemic white matter injury. Microglia, as resident immune cells in the brain, are the main cells undergoing oxidative stress response. However, the role and molecular mechanism of oxidative stress in microglia have not been clearly elucidated during white matter ischemia.

METHODS

Extensive histological analysis of the corpus callosum was performed in BCAS mice at different time points to assess white matter injury, oxidative stress and microglial activation. Flow cytometric sorting and transcriptomic sequencing were combined to explore the underlying mechanisms regulating microglial oxidative stress and functional phenotypes. The expression of critical molecule in microglia was regulated using Cx3cr1CreER mice and clinical-stage drugs to assess its effect on white matter injury and cognitive function.

RESULTS

Our study identified nuclear factor erythroid-2 related factor 2 (Nrf2) as a key transcription factor regulating oxidative stress and functional phenotype in microglia. Interestingly, we found that the sustained decrease in transiently upregulated expression of Nrf2 following chronic cerebral hypoperfusion resulted in abnormal microglial activation and white matter injury. In addition, high loads of myelin debris promoted lipid peroxidation and ferroptosis in microglia with diminished antioxidant function. Microglia with pharmacologically or genetically stimulated Nrf2 expression exhibited enhanced resistance to ferroptosis and pro-regenerative properties to myelination due to lipid and iron metabolism reprogramming.

CONCLUSION

Weakened Nrf2-mediated antioxidant responses in microglia induced metabolic disturbances and ferroptosis during chronic cerebral hypoperfusion. Targeted enhancement of Nrf2 expression in microglia may be a potential therapeutic strategy for ischemic white matter injury.

Ferroptosis and its impact on common diseases

Ferroptosis is a novel form of programmed cell death characterized by iron accumulation, lipid peroxidation, and a decline in antioxidant capacity, all of which are regulated by gene expression. The onset of numerous diseases is closely associated with ferroptosis. Common diseases affect a large population, reduce the quality of life, and impose an increased burden on the healthcare system. The role of ferroptosis in common diseases, its therapeutic potential, and even its translation into clinical drug treatments are currently significant research topics worldwide. This study preliminarily explores the theoretical basis of ferroptosis, its mechanism and treatment prospect in common diseases including ischaemia-reperfusion injury, inflammatory bowel diseases, liver fibrosis, acute kidney injury, diabetic kidney disease, stroke, Alzheimer's disease, cardiovascular disease, immune and cancer. This review provides a theoretical foundation for the further study and development of ferroptosis, as well as for the prevention and treatment of common diseases.

Unveiling ferroptosis: a new frontier in skin disease research

Ferroptosis, a form of regulated cell death distinct from apoptosis, necrosis, and autophagy, is increasingly recognized for its role in skin disease pathology. Characterized by iron accumulation and lipid peroxidation, ferroptosis has been implicated in the progression of various skin conditions, including psoriasis, photosensitive dermatitis, and melanoma. This review provides an in-depth analysis of the molecular mechanisms underlying ferroptosis and compares its cellular effects with other forms of cell death in the context of skin health and disease. We systematically examine the role of ferroptosis in five specific skin diseases, including ichthyosis, psoriasis, polymorphous light eruption (PMLE), vitiligo, and melanoma, detailing its influence on disease pathogenesis and progression. Moreover, we explore the current clinical landscape of ferroptosis-targeted therapies, discussing their potential in managing and treating skin diseases. Our aim is to shed light on the therapeutic potential of modulating ferroptosis in skin disease research and practice.

Functional Amino Acids in the Regulation of Bone and Its Diseases

Bone as a vigorous tissue is constantly undergoing bone remodeling. The homeostasis of bone remodeling requires combined efforts of multifarious bone cells. Amino acids (AA), known as essential components of life support, are closely related to the regulation of bone homeostasis. In recent years, the concept of functional amino acids (FAAs) has been proposed, which is defined as AA that regulate key metabolic pathways to improve health, survival, growth, development, lactation, and reproduction of organisms, to highlight their outstanding contributions in the body. In the hope of exploring new therapeutic strategies, this review focus on summarizing recent progress in the vital role of FAAs in bone homeostasis maintaining and potential implications of FAAs in bone-related diseases, and discussing related mechanisms. The results showed that FAAs are closely related to bone metabolism and therapeutic strategy targeting FAAs metabolism is one of the future trends for bone disorders, while the explorations about possible impact of FAAs-based diets are still limited.

Regulatory mechanisms of amino acids in ferroptosis

Ferroptosis, an iron-dependent non-apoptotic regulated cell death process, is associated with the pathogenesis of various diseases. Amino acids, which are indispensable substrates of vital activities, significantly regulate ferroptosis. Amino acid metabolism is involved in maintaining iron and lipid homeostasis and redox balance. The regulatory effects of amino acids on ferroptosis are complex. An amino acid may exert contrasting effects on ferroptosis depending on the context. This review systematically and comprehensively summarized the distinct roles of amino acids in regulating ferroptosis and highlighted the emerging opportunities to develop clinical therapeutic strategies targeting amino acid-mediated ferroptosis.

Global prevalence of diet low in calcium and the disease burden: results from the Global Burden of Disease Study 2019

BACKGROUND

Due to the essential role of calcium in vital biological functions, diet low in calcium (DLC) is associated with various diseases. However, there is a lack of study about the current prevalence and health burden due to DLC using reliable data sources.

METHODS

We used data from the Global Burden of Disease study 2019 (GBD 2019) to estimate the prevalence and health burden of DLC in 204 countries from 1990 to 2019, by age, sex, and sociodemographic index (SDI). The estimates were produced in DisMod-MR 2.1, a Bayesian meta-regression tool. Summary exposure value (SEV) was used to show the prevalence of DLC, while diseases adjusted life year (DALY) was used to represent the disease burden. The disease burden was estimated for DLC-induced colorectal cancer. Spearman Rank Order correlation was used for correlation analysis, and estimated annual percentage (EAPC) was used to reflect the temporal trends.

RESULTS

From 1990 to 2019, the global prevalence of DLC decreased (EAPC of SEV, -0.47; 95% CI, -0.5 to -0.43), but have increased in Oceania region and in many countries, such as United Arab Emirates, New Zealand, Japan, and France. The global DALYs associated with low in calcium were estimated to be 3.14 million (95% uncertainty interval (UI), 2.25-4.26 million) in 2019, with an age standardized rate of 38.2 (95% UI, 27.2-51.8) per 100,000. Unlike the prevalence, the global age standardized DALY rates has remained unchanged (EAPC, -0.03; 95% CI, -0.12 to 0.07), but has increased in over 80 of the 204 countries, located mainly in Asia, Africa, and South America. In all years and regions, the age standardized SEV and DALY rates were higher in male people than that in female people. The prevalence (rho = -0.823; P < 0.001) and disease burden (rho = -0.433; P < 0.001) associated with diet in low calcium were strongly correlated to SDI. The prevalence decreased with age, but the DALY rates increased with age and peaked at about 90 years. The prevalence of DLC has decreased worldwide and in most countries, but the disease burden of DLC induced colorectal cancer has increased in over 40% of countries worldwide.

CONCLUSION

Countries with low sociodemographic level and male people are more likely to experience the risk of DLC and related disease burden. Related measures in improve dietary calcium intake are in need to address diet in low calcium related health problems.