Association of environmental cadmium exposure and bone remodeling in women over 50 years of age

Mechanisms of Heavy Metal Cadmium (Cd)-Induced Malignancy

The environmental pollution of cadmium is worsening, and its significant carcinogenic effects on humans have been confirmed. Cadmium can induce cancer through various signaling pathways, including the ERK/JNK/p38MAPK, PI3K/AKT/mTOR, NF-κB, and Wnt. It can also cause cancer by directly damaging DNA and inhibiting DNA repair systems, or through epigenetic mechanisms such as abnormal DNA methylation, LncRNA, and microRNA. However, the detailed mechanisms of Cd-induced cancer are still not fully understood and require further investigation.

Impacts and mechanisms of PM2.5 on bone

Osteoporosis is a metabolic bone disease, which is characterized by a decreased bone mass and deterioration of bone microstructure, resulting in increased bone fragility and a higher risk of fracture. The main pathological process of osteoporosis is the dynamic imbalance between bone absorption and bone formation, which can be caused by various factors such as air pollution. Particulate matter (PM)2.5 refers to the fine particles in the atmosphere, which are small in volume and large in specific surface area. These particles are prone to carrying toxic substances and have negative effects on several extrapulmonary organs, including bones. In this review, we present relevant data from studies, which show that PM2.5 is associated with abnormal bone turnover and osteoporosis. PM2.5 may cause or aggravate bone loss by stimulating an inflammatory response, inducing oxidative damage, reducing estrogen efficiency by competitive binding to estrogen receptors, or endocrine disorder mediated by binding with aromatic hydrocarbon receptors, and affecting the synthesis of vitamin D to reduce calcium absorption. The cellular and molecular mechanisms involved in these processes are also summarized in this review.

Earthworm mucus contributes significantly to the accumulation of soil cadmium in tomato seedlings

Whether earthworm mucus affects Cd transport behavior in soil-plant systems remains uncertain. Consequently, this study thoroughly assessed the impacts of earthworm mucus on plant growth and physiological responses, plant Cd accumulation, translocation, and distribution, as well as soil characteristics and Cd fractionation in a soil-plant (tomato seedling) system. Results demonstrated that the earthworm inoculation considerably enhanced plant Cd uptake and decreased plant Cd translocation, the effects of which were appreciably less significant than those of the earthworm mucus. This suggested that earthworm mucus may play a crucial role in the way earthworms influence plant Cd uptake and translocation. Moreover, the artificial mucus, which contained identical inorganic nitrogen contents to those in earthworm mucus, had no significant effect on plant Cd accumulation or translocation, implying that components other than inorganic nitrogen in the earthworm mucus may have contributed significantly to the overall effects of the mucus. Compared with the control, the earthworm mucus most substantially increased the root Cd content, the Cd accumulation amount of root and whole plant, and root Cd BCF by 93.7 %, 221.3 %, 72.2 %, and 93.7 %, respectively, while notably reducing the Cd TF by 48.2 %, which may be ascribed to the earthworm mucus's significant impacts on tomato seedling growth and physiological indicators, its considerable influences on the subcellular components and chemical species of root Cd, and its substantial effects on the soil characteristics and soil Cd fractionation, as revealed by correlation analysis. Redundancy analysis further suggested that the most prominent impacts of earthworm mucus may have been due to its considerable reduction of soil pH, improvement of soil DOC content, and enhancement of the exchangeable Cd fraction in soil. This work may help better understand how earthworm mucus influences the transport behavior of metals in soil-plant systems.

Cadmium accelerates autophagy of osteocytes by inhibiting the PI3K/AKT/mTOR signaling pathway

Cadmium (Cd) can damage bone cells and cause osteoporosis. Osteocytes are the most numerous bone cells and also important target cells for Cd-induced osteotoxic damage. Autophagy plays important role in the progression of osteoporosis. However, osteocyte autophagy in Cd-induced bone injury is not well characterized. Thus, we established a Cd-induced bone injury model in BALB/c mice and a cellular damage model in MLO-Y4 cells. Aqueous Cd exposure for 16 months showed an increase in plasma alkaline phosphatase (ALP) activity and increase in urine calcium (Ca) and phosphorus (P) concentrations in vivo. Moreover, expression level of autophagy-related microtubule-associated protein 1A/1B-light chain 3 II (LC3II) and autophagy-related 5 (ATG5) proteins were induced, and the expression of sequestosome-1 (p62) was reduced, along with Cd-induced trabecular bone damage. In addition, Cd inhibited the phosphorylation of mammalian target of rapamycin (mTOR), protein kinase B (AKT), and phosphatidylinositol 3-kinase (PI3K). In vitro, 80 μM Cd concentrations exposure upregulated LC3II protein expression, and downregulated of p62 protein expression. Similarly, we found that treatment with 80 μM Cd resulted in a reduction in the phosphorylation levels of mTOR, AKT, and PI3K. Further experiments revealed that addition of rapamycin, an autophagy inducer, enhanced autophagy and alleviated the Cd-induced damage to MLO-Y4 cells. The findings of our study reveal for the first time that Cd causes damage to both bone and osteocytes, as well as induces autophagy in osteocytes and inhibits PI3K/AKT/mTOR signaling, which could be a protective mechanism against Cd-induced bone injury.

Association between dietary intake of α-tocopherol and cadmium related osteoporosis in population ≥ 50 years

INTRODUCTION

To analyze the association between α-tocopherol intake and cadmium (Cd) exposure and osteoporosis in population ≥ 50 years.

MATERIALS AND METHODS

Sociodemographic data, physical examination, and laboratory indicators including serum Cd level and dietary α-tocopherol intake of 8459 participants were extracted from the National Health and Nutrition Examination Survey (NHANES) database in this cross-sectional study. The associations between α-tocopherol intake, serum Cd levels and osteoporosis were evaluated using univariate and multivariate logistic regression analyses, with the estimated value (β), odds ratios (ORs) and 95% confidence intervals (CIs). We further explored the impact of α-tocopherol intake on Cd exposure and the bone mineral density (BMD) in total femur and femur neck.

RESULTS

A total of 543 old adults suffered from osteoporosis. The serum Cd level (0.52 μg/L vs. 0.37 μg/L) and α-tocopherol intake (5.28 mg vs. 6.50 mg) were statistical different in osteoporosis group and non-osteoporosis group, respectively. High level of Cd exposure was related to the increased risk of osteoporosis [OR = 1.60, 95% CI (1.15-2.21)]. In the total femur, α-tocopherol intake may improve the loss of BMD that associated with Cd exposure [β = - 0.047, P = 0.037]. Moreover, high α-tocopherol intake combined with low Cd exposure [OR = 0.54, 95% CI (0.36-0.81)] was linked to the decreased risk of osteoporosis comparing with low α-tocopherol intake combined with high Cd exposure.

CONCLUSION

High α-tocopherol intake may improve the Cd-related osteoporosis and loss of BMD that could provide some dietary reference for prevention of osteoporosis in population ≥ 50 years old.

Metabolome analysis reveals the toxic effects of cadmium exposure on the egg sac of spider Pardosa pseudoannulata

The investigation of the toxic effects of cadmium (Cd) on rice field invertebrates has attracted accumulating attention. Spider grants a novel insight into the impacts of Cd stress on invertebrates, but the effects of Cd-induced toxicity and molecular response mechanism of related metabolites in spider's egg sacs remain elusive. This investigation found that Cd stress distinctively decreased vitellogenin (Vg) content and hatched spiderlings numbers in the egg sac of Pardosa pseudoannulata. In addition, Cd stress exerted oxidative stress in the egg sac, manifested as the increase of superoxide dismutase and malondialdehyde levels. Further results showed that Cd exposure could affect egg sacs' energy metabolism, including protein and lipid contents. Metabolome analysis generated 73 up-regulated and 63 down-regulated differentially expressed metabolites (DEMs), mainly affecting phenylalanine metabolism, alpha-linolenic acid metabolism, pentose phosphate pathway, and biosynthesis of amino acids. Specifically, pathway analysis showed that Cd exposure down-regulated several key factors, including tyrosine, L-phenylalanine, O-phospho-L-serine, and L-cystathionine, and inhibited the metabolism of amino acids in the egg sacs. The subsequent correlation analysis found that three metabolite indicators, 9-Oxo-ODE, PG (17:0/18:2), and PE (17:0/20:5), were the dominant contributors to the egg sec's properties (i.e., Vg content and gained spiderlings). Collectively, this study hopes to provide valuable data for the protection of rice field spiders and offer novel perspectives for Cd pollution assessment and management.

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.

Toxicity of cadmium salts on indicators of embryogenesis of rats

Cadmium is a toxic heavy metal which is considered a dangerous environmental pollutant and has a detrimental effect on the organs of the reproductive system, the period of implantation and the development of embryos. The experiment presented in this article established the effect of cadmium salts (chloride and citrate) on the general progress of embryogenesis. For this purpose, 60 rats were randomly divided into three groups: control, experimental group with cadmium chloride exposure and experimental group with cadmium citrate exposure. Cadmium chloride solvent, cadmium citrate solvent at a dose of 1.0 mg/kg and distilled intragastric water were injected from the first to the thirteenth (first subgroup) and from the first to the twentieth days of embryogenesis (second subgroup). When cadmium chloride was injected, total embryonic (by 4.24 and 3.67 times), pre-implantation (by 6.50 and 14.03 times) and post-implantation mortality (by 3.07 and 2.49 times) increased with a reduction of the number of surviving fetuses by 24.0% and 25.9% compared with the control group on the 13th and 20th days of embryogenesis respectively. At the same time, during exposure to cadmium citrate, indicators of total embryonic mortality increased by 4.02 and 3.52 times, pre-implantation mortality by 6.04 and 13.03 times, and post-implantation mortality by 3.09 and 2.26 times, and indicators of the number of live fetuses decreased by 18.3% and 22.2% in relation to the control group. When determining the accumulation of cadmium in embryos on the 20th day of gestation, polyelement analysis of biological materials using the atomic emission method with electric arc atomization revealed a 15.83-fold increase in cadmium chloride and 9.00 times in cadmium citrate relative to the control group. Embryolethality rates increased in animals of both experimental groups while the number of live fetuses per female decreased, which indicated an obvious embryotoxic effect of cadmium compounds. It is would be useful to conduct histological studies, which will help detect changes at the tissue level and possibly explain the level of embryonic mortality.

The mechanism of the cadmium-induced toxicity and cellular response in the liver

Cadmium is a toxic element to which man can be exposed at work or in the environment. Cd's most salient toxicological property is its exceptionally long half-life in the human body. Once absorbed, Cd accumulates in the human body, particularly in the liver. The cellular actions of Cd are extensively documented, but the molecular mechanisms underlying these actions are still not resolved. The liver manages the cadmium to eliminate it by a diverse mechanism of action. Still, many cellular and physiological responses are executed in the task, leading to worse liver damage, ranging from steatosis, steatohepatitis, and eventually hepatocellular carcinoma. The progression of cadmium-induced liver damage is complex, and it is well-known the cellular response that depends on the time in which the metal is present, ranging from oxidative stress, apoptosis, adipogenesis, and failures in autophagy. In the present work, we aim to present a review of the current knowledge of cadmium toxicity and the cellular response in the liver.

Simultaneous immobilization of arsenic, lead and cadmium by magnesium-aluminum modified biochar in mining soil

Owing to the human activities such as smelting and mining, arsenic (As), lead (Pb) and cadmium (Cd) seriously polluted the soil of non-ferrous metal mining areas, thus efficient methods for the simultaneous immobilization of the three heavy metals are urgently needed. In the present study, Mg-Al modified biochars (MABs) were synthesized through a simple one-pot pyrolysis method to immobilize the three heavy metals. According to the BET (Brunauer-Emmett-Teller) test method, MABs had larger specific surface areas than biochar. Compared to the materials obtained at 300 °C and 700 °C, MAB with a pyrolysis temperature of 500 °C (MAB 500) had a significant immobilization effect on As, Pb and Cd in the Gansu mining area. Compared with BC, the removal efficiencies of As, Pb and Cd increased from -62%, 17% and 5% to 52%, 100% and 66%, respectively. And the toxicity characteristic leaching procedure (TCLP) test showed that the leaching concentrations of the three heavy metals in the treated soil were all lower than the standard value. X-ray photoelectron spectroscopy and kinetic experiments showed that there were various mechanisms in the immobilization process of the three heavy metals, and the large specific surface area and the multi-Mg/Al-OH of MABs play an important role in this process. More charges were provided by larger specific surface for ion exchange with heavy metals. In addition, larger specific surface area also provided more adsorption sites. More complex sites were provided by Mg/Al-OH to form Mg/Al-O-M then immobilize the heavy metals. In summary, the immobilization mechanism may involve electrostatic attraction, precipitation/co-precipitation, and surface complexation.

The Association Between Cadmium Exposure and Osteoporosis: A Longitudinal Study and Predictive Model in a Chinese Female Population

Objective: The association between cadmium exposure and osteoporosis has been rarely reported in longitudinal studies. In this study, we investigated the association between osteoporosis and cadmium exposure and developed predictive models in women in a longitudinal cohort. Materials and Methods: In total, 488 women living in southeastern China were included at baseline (1998). Cadmium in blood (BCd) and urine (UCd) and also renal dysfunction biomarkers and bone mineral density (BMD) were determined both at baseline and follow-up. A total of 307 subjects were finally included after excluding subjects that did not have exposure or effect biomarkers. Osteoporosis was defined based on T score ≤ -2.5. Multiple linear regression and multivariate logistic analysis were used to show the association between baseline data and follow-up osteoporosis. Based on the identified associated factors, nomograms were developed to graphically calculate the individual risk of osteoporosis. Results: The baseline BMD in subjects with osteoporosis was significantly lower than that in subjects without osteoporosis (0.59 vs. 0.71 g/cm2, p < 0.05). The prevalence of low bone mass at baseline was higher in subjects with osteoporosis than in those without osteoporosis (23.5 vs. 7.2%, p = 0.001). Logistic regression analysis demonstrated that age [odds ratio (OR) = 1.21, 95% confidence interval (CI): 1.16-1.27], UCd (OR = 1.03, 95% CI: 1.002-1.06) and the presence of low BMD (OR = 3.84, 95% CI: 1.49-9.89) were independent risk factors for osteoporosis. For those subjects with normal baseline BMD, age, UCd, and baseline BMD were also independent risk factors for osteoporosis. The OR value was 1.16 (95% CI: 1.10-1.22) for age, 2.27 (95% CI: 1.03-4.99) for UCd > 10 μg/g creatinine, and 0.39 (95% CI: 0.21-0.72) for BMDbaseline. We developed two nomograms to predict the risk of osteoporosis. The area under the curve was 0.88 (95% CI: 0.84-0.92) for total population and was 0.88 (95% CI: 0.84-0.92) for subjects with normal baseline BMD, respectively. Conclusion: Baseline age, UCd, and BMD were associated with follow-up osteoporosis in women. Nomograms showed good performance in predicting the risk of osteoporosis.