Low levels of cadmium exposure affect bone by inhibiting Lgr4 expression in osteoblasts and osteoclasts

Determining the Feasibility of a Cadmium Exposure Model to Activate the Inflammatory Arm of PANoptosis in Murine Monocytes

A prevalence of cigarette smoking can cause the accumulation of cadmium (Cd2+) in the lungs, kidneys, and blood. The effects of exposure can cause multiple chronic disease types to emerge in the affected organ systems. The only moderately effective therapeutic option is chelation therapy; the health risks associated with this therapy have caused much criticism. The disease types associated with Cd2+ toxicity have inflammatory components and greatly impact innate immunity. These factors are affected at the cellular level and cause pathways like apoptosis, pyroptosis, and necroptosis. A development in understanding these pathways stipulates that these three pathways act as one complex of pathways, known together as PANoptosis. The inflammatory mechanisms of PANoptosis are particularly interesting in Cd2+ toxicity due to its inflammatory effects. Proteins in the gasdermin family act to release inflammatory cytokines, like interleukin-1β, into the extracellular environment. Cytokines cause inflammatory disease pathologies like fibrosis and cancer. RAW 264.7 monocytes are key in the murine immune system and provide an excellent model to investigate Cd2+ toxicity. Exposure of 0-15 µM CdCl2 was sufficient to increase expression of cleaved gasdermin D (GSDMD) and gasdermin E (GSDME) in this cell type. Cd2+ also exhibits a dose-dependent cytotoxicity in this cell type.

Effects and mechanisms of microbial ecology and diversity on phytoremediation of cadmium-contaminated soil under the influence of biodegradable organic acids

In recent years, heavy metal pollution has become a global environmental problem and poses a great threat to the health of people and ecosystems. Therefore, strategies for the effective remediation of Cd from contaminated soil are urgently needed. In this study, ryegrass was utilized as a remediation plant, and its remediation potential was enhanced through the application of Citric Acid (CA) in conjunction with Bacillus megaterium (B. megaterium). The P3 treatment (CA + Bacillus megaterium) exhibited a significantly higher efficiency in promoting cadmium extraction by ryegrass, resulting in a 1.79-fold increase in shoot cadmium accumulation compared to the control group (CK) with no Bacillus megaterium or CA. Moreover, the P3 treatment led to an increased abundance of Actinobacteriota, Acidobacteriota, and Patescibacteria in the rhizosphere. The concentration of amino derivatives (such as betaine, sulfolithocholylglycine, N-alpha-acetyl-lysine, glycocholic acid, arginyl-threonine) showed significant upregulation following the P3 treatment. In summary, this study proposes a viable approach for phytoremediation of soil contaminated with cadmium by harnessing the mobilizing abilities of soil bacteria.

The Effects of Seleno-Methionine in Cadmium-Challenged Human Primary Chondrocytes

Cadmium (Cd) is a potentially toxic element able to interfere with cellular functions and lead to disease or even death. Cd accumulation has been demonstrated in cartilage, where it can induce damage in joints. The aim of this study was to evaluate the effect of CdCl2 on primary cultures of human chondrocytes and the possible protective effect of seleno-methionine (Se-Met). Human primary articular chondrocytes were cultured and treated as follows: control groups, cells challenged with 7.5 μM and 10 μM CdCl2 alone, and cells pretreated with 10 and 20 μM Se-Met and then challenged with 7.5 μM and 10 μM CdCl2. Twenty-four hours after incubation, cell viability, histological evaluation with hematoxylin-eosin stain, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed. Furthermore, reverse transcription-PCR was carried out to evaluate mRNA levels of BAX, BAK1, CASP-3, and CASP-9. After CdCl2 challenge at both doses, a reduced cell viability and an overexpression of BAX, BAK1, CASP-3, and CASP-9 genes, as well as a high number of TUNEL-positive cells, were demonstrated, all parameters becoming higher as the dose of CdCl2 was increased. The pretreatment with Se-Met lowered the expression of all considered genes, improved cell viability and morphological changes, and reduced the number of TUNEL-positive cells. It was concluded that Se-Met plays a protective role against CdCl2-induced structural and functional changes in chondrocytes in vitro, as it improved cell viability and showed a positive role in the context of the apoptotic pathways. It is therefore suggested that a translational, multifaceted approach, with plant-based diets, bioactive functional foods, nutraceuticals, micronutrients, and drugs, is possibly advisable in situations of environmental pollution caused by potentially toxic elements.

Prolonged Cadmium Exposure and Osteoclastogenesis: A Mechanistic Mouse and in Vitro Study

BACKGROUND

Cadmium (Cd) is a highly toxic and widespread environmental oxidative stressor that causes a myriad of health problems, including osteoporosis and bone damage. Although nuclear factor erythroid 2-related factor 2 (NRF2) and its Cap 'n' Collar and basic region Leucine Zipper (CNC-bZIP) family member nuclear factor erythroid 2-related factor 1 (NRF1) coordinate various stress responses by regulating the transcription of a variety of antioxidant and cytoprotective genes, they play distinct roles in bone metabolism and remodeling. However, the precise roles of both transcription factors in bone loss induced by prolonged Cd exposure remain unclear.

OBJECTIVES

We aimed to understand the molecular mechanisms underlying Cd-induced bone loss, focusing mainly on the roles of NRF2 and NRF1 in osteoclastogenesis provoked by Cd.

METHODS

Male wild-type (WT), global Nrf2-knockout (N r f 2 - / - ) and myeloid-specific Nrf2 knockout [Nrf2(M)-KO] mice were administered Cd (50 or 100  ppm ) via drinking water for 8 or 16 wk, followed by micro-computed tomography, histological analyses, and plasma biochemical testing. Osteoclastogenesis was evaluated using bone marrow-derived osteoclast progenitor cells (BM-OPCs) and RAW 264.7 cells in the presence of Cd (10 or 20  nM ) with a combination of genetic and chemical modulations targeting NRF2 and NRF1.

RESULTS

Compared with relevant control mice, global N r f 2 - / - or Nrf2(M)-KO mice showed exacerbated bone loss and augmented osteoclast activity following exposure to 100  ppm Cd in drinking water for up to 16 wk. In vitro osteoclastogenic analyses suggested that Nrf2-deficient BM-OPCs and RAW 264.7 cells responded more robustly to low levels of Cd (up to 20  nM ) with regard to osteoclast differentiation compared with WT cells. Further mechanistic studies supported a compensatory up-regulation of long isoform of NRF1 (L-NRF1) and subsequent induction of nuclear factor of activated T cells, cytoplasmic, calcineurin dependent 1 (NFATc1) as the key molecular events in the Nrf2 deficiency-worsened and Cd-provoked osteoclastogenesis. L-Nrf1 silenced (via lentiviral means) Nrf2-knockdown (KD) RAW cells exposed to Cd showed dramatically different NFATc1 and subsequent osteoclastogenesis outcomes compared with the cells of Nrf2-KD alone exposed to Cd, suggesting a mitigating effect of the Nrf1 silencing. In addition, suppression of reactive oxygen species by exogenous antioxidants N -acetyl-l-cysteine (2  mM ) and mitoquinone mesylate (MitoQ; 0.2 μ M ) mitigated the L-NRF1-associated effects on NFATc1-driven osteoclastogenesis outcomes in Cd-exposed Nrf2-KD cells.

CONCLUSIONS

This in vivo and in vitro study supported the authors' hypothesis that Cd exposure caused bone loss, in which NRF2 and L-NRF1 responded to Cd and osteoclastogenic stimuli in a cooperative, but contradictive, manner to coordinate Nfatc1 expression, osteoclastogenesis and thus bone homeostasis. Our study suggests a novel strategy targeting NRF2 and L-NRF1 to prevent and treat the bone toxicity of Cd. https://doi.org/10.1289/EHP13849.

Recent advances of NFATc1 in rheumatoid arthritis-related bone destruction: mechanisms and potential therapeutic targets

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by inflammation of the synovial tissue and joint bone destruction, often leading to significant disability. The main pathological manifestation of joint deformity in RA patients is bone destruction, which occurs due to the differentiation and proliferation of osteoclasts. The transcription factor nuclear factor-activated T cell 1 (NFATc1) plays a crucial role in this process. The regulation of NFATc1 in osteoclast differentiation is influenced by three main factors. Firstly, NFATc1 is activated through the upstream nuclear factor kappa-B ligand (RANKL)/RANK signaling pathway. Secondly, the Ca2+-related co-stimulatory signaling pathway amplifies NFATc1 activity. Finally, negative regulation of NFATc1 occurs through the action of cytokines such as B-cell Lymphoma 6 (Bcl-6), interferon regulatory factor 8 (IRF8), MAF basic leucine zipper transcription factor B (MafB), and LIM homeobox 2 (Lhx2). These three phases collectively govern NFATc1 transcription and subsequently affect the expression of downstream target genes including TRAF6 and NF-κB. Ultimately, this intricate regulatory network mediates osteoclast differentiation, fusion, and the degradation of both organic and inorganic components of the bone matrix. This review provides a comprehensive summary of recent advances in understanding the mechanism of NFATc1 in the context of RA-related bone destruction and discusses potential therapeutic agents that target NFATc1, with the aim of offering valuable insights for future research in the field of RA. To assess their potential as therapeutic agents for RA, we conducted a drug-like analysis of potential drugs with precise structures.

SIRT1 regulates osteoblast senescence through SOD2 acetylation and mitochondrial dysfunction in the progression of Osteoporosis caused by Cadmium exposure

Environmental Cadmium (Cd) is a toxicant with widespread exposure, documented adverse effects on bone homeostasis, and makes the onset of osteoporosis (OP), one of the age-related chronic diseases an enormous burden to modern societies worldwide. Aging is the largest risk factor for a multitude of age-related diseases and osteoblasts senescence reduces bone formation and is a key factor for osteoporosis. Despite anti-aging molecules the nuclear silent information regulator of transcription 1 (SIRT1) actions in chondrocytes and bone cells are critical for normal skeletal development and homeostasis, much less is known about the role of SIRT1 in osteoporosis. Here, we aim to demonstrate that SIRT1 mediates osteoblasts' senescence response to OP caused by Cd. The senescent osteoblasts accumulation and their viability were analyzed after Cd exposure. To explore the effects and mechanism of SIRT1 in Cd-induced osteoblastic senescence, we generated SIRT1-overexpressed osteoblast and SIRT1 conditional overexpression in the rat femur. Meanwhile, the OP rat model was established by removing bilateral ovaries. We found decreased SIRT1 expression and senescent osteoblasts accumulation after Cd exposure. Meanwhile, Cd exposure increased P53, P16INK4a, and P21CIPI proteins level, triggered DNA damage response (DDR) through the phosphorylation of ATM and H2AX, and caused mitochondrial dysfunction by the increased acetylation of SOD2 and excessive mitophagy. SIRT1 overexpression attenuated DDR and mitochondrial dysfunction and downregulated the increase of hall makers senescence caused by Cd in osteoblasts. We found overexpression of osteoblastic SIRT1 protects against Cd-induced senescence, which is likely driven by ATM-mediated DDR and SOD2ace-mediated mitochondrial dysfunction. Our study demonstrates the mechanism of SIRT1 in mediating bone homeostasis via senescence. Further mechanistic studies using specific SIRT1 mutations elucidating how SIRT1 modulates bone cell senescence, will provide new therapeutic strategies for human osteoporosis.

Association between Environmental Cadmium Exposure and Osteoporosis Risk in Postmenopausal Women: A Systematic Review and Meta-Analysis

Osteoporosis is a common and serious health issue among postmenopausal women. We conducted a systematic review and meta-analysis study to determine whether environmental exposure to cadmium (Cd) is a risk factor for postmenopausal osteoporosis. A PROSPERO-registered review of the literature was performed on studies evaluating the relationship between urinary Cd (UCd) concentration, an indicator of long-term Cd exposure, and bone mineral density or osteoporosis in women aged 50 years and older. PubMed, Embase, Science Direct, Web of Science, and B-on databases were searched for articles published between 2008 and 2021. The association between UCd levels and osteoporosis risk was assessed by pooled odds ratio (OR) and 95% confidence interval (CI) using random-effect models. Ten cross-sectional studies were included in the qualitative analysis, of which five were used for meta-analysis. We separately assessed the risk of osteoporosis in women exposed to Cd at low environmental levels (n = 5895; UCd ≥ 0.5 μg/g creatinine versus UCd < 0.5 μg/g creatinine) and high environmental levels (n = 1864; UCd ≥ 5 μg/g creatinine versus UCd < 5 μg/g creatinine). The pooled OR for postmenopausal osteoporosis was 1.95 (95% CI: 1.39−2.73, p < 0.001) in the low exposure level group and 1.99 (95% CI: 1.04−3.82, p = 0.040) in the high exposure level group. This study indicates that environmental Cd exposure, even at low levels, may be a risk factor for osteoporosis in postmenopausal women. Further research based on prospective studies is needed to validate these findings.