Cell Viability and Immune Response to Low Concentrations of Nickel and Cadmium: An In Vitro Model

Association of Blood Heavy Metals with Diabetic Foot Ulcers in U.S. Adults with Diabetes: Insights from the 1999-2004 NHANES Data

INTRODUCTION

Diabetic foot ulcers (DFU) are serious complications of diabetes. These ulcers significantly increase the risk of amputations. Many studies have examined how blood heavy metals affect insulin secretion in diabetes. However, research linking blood heavy metal exposure to DFU is limited. This study aims to explore the connection between blood heavy metal exposure and DFU in people with diabetes.

METHODS

This cross-sectional study used data from the 1999-2004 cycle of the National Health and Nutrition Examination Survey (NHANES). Researchers measured blood levels of lead (Pb) and cadmium (Cd) using inductively coupled plasma mass spectrometry (ICP-MS). Four logistic regression models assessed the relationship between blood heavy metals and the prevalence of DFU. The models adjusted for potential confounding factors. Additionally, smooth curve fitting and piecewise regression analyses were conducted to investigate the correlation further. Subgroup analyses and interaction tests helped evaluate consistency across the general population.

RESULTS

A total of 1664 participants aged 40 years or older with diabetes were included in the final analysis. The average age is 64.66 ± 11.79 years, with 52.52% being male and 47.48% being female. Among these individuals, 135 (8.11%) were diagnosed with DFU. Statistical modeling revealed a significant positive correlation between blood cadmium (Cd) levels and the prevalence of DFU. Specifically, model 4, which was the fully adjusted model, indicated that for each unit increase in blood Cd level, there was a corresponding 64% increase in DFU prevalence [OR = 1.64; 95% CI (1.42-1.89), p = 0.004]. Further analysis through smooth curve fitting demonstrated a significant linear relationship between blood Cd levels and DFU prevalence.

CONCLUSIONS

This study identified a positive correlation between blood cadmium (Cd) levels and the prevalence of DFU. These results suggest that monitoring blood Cd levels in patients with diabetes during follow-up may be important for preventing the development of DFU. However, further prospective studies are necessary to provide additional evidence.

Cadmium exposure in infants and children: toxicity, health effects, dietary risk assessment and mitigation strategies

As a non-essential metal, cadmium (Cd) poses a significant threat to food safety and public health. This risk is particularly pronounced for infants and young children due to their high food consumption relative to body weight and immature physiological systems. This review examines the health risks associated with Cd exposure, particularly during the prenatal period through adolescence. It evaluates the prevalence of Cd-rich foods in children's diets and their intake levels across various countries. The review demonstrates that Cd exposure is associated with neurodevelopmental disorders, immune dysfunction, and cardiovascular diseases. It also highlights geographic differences in exposure, with some Asian countries, such as Thailand and China, exhibiting higher overall levels of Cd intake among children compared to other regions. This review presents several recommendations to mitigate Cd intake during early childhood, including reducing the Cd content in food, inhibiting Cd absorption, and promoting its excretion from the body. To minimize the risk of dietary Cd intake in children, it is recommended that stringent regulations of Cd limits in children's food be implemented, alongside a coordinated multi-stakeholder effort. This review provides important insights into effective public health policy development, laying the foundation for achieving broader public health goals.

Road dust exposure and human corneal damage in a plateau high geological background provincial capital city: Spatial distribution, sources, bioaccessibility, and cytotoxicity of dust heavy metals

Ocular surface diseases are common in the plateau city, Kunming China, the continued daily exposure to heavy metals in dust may be an important inducement. In this study, the 150 road dust samples from five functional areas in Kunming were collected. The concentrations, distribution, possible sources, and bioaccessibility of heavy metals were analyzed. The adverse effects of dust extracts on human corneal epithelial cells and the underlying mechanisms were also assessed. The concentrations (mg·kg-1) of As (19.1), Cd (2.67), Cr (90.5), Cu (123), Pb (78.4), and Zn (389) in road dust were higher than the soil background, with commercial and residential areas showing the highest pollution. Their bioaccessibility in artificial tears was As (6.59 %) > Cu (5.11 %) > Ni (1.47 %) > Cr (1.17 %) > Mn (0.84 %) > Cd (0.76 %) > Zn (0.50 %) > Pb (0.31 %). The two main sources of heavy metals included tire and mechanical abrasion (24.5 %) and traffic exhaust (21.6 %). All dust extracts induced cytotoxicity, evidenced by stronger inhibition of cell viability, higher production of ROS, and altered mRNA expression of antioxidant enzymes and cell cycle-related genes, with commercial- areas-2 (CA2)-dust extract showing the greatest oxidative damage and cell cycle arrest. Our data may provide new evidence that dust exposure in high geological background cities could trigger human cornea damage.

Mechanisms of Cd-induced Cytotoxicity in Normal Human Skin Keratinocytes: Implication for Human Health

Cadmium (Cd) is one of the toxic heavy metals found widely in the environment. Skin is an important target organ of Cd exposure. However, the adverse effects of Cd on human skin are still not well known. In this study, normal human skin keratinocytes (HaCaT cells) were studied for changes in cell viability, morphology, DNA damage, cycle, apoptosis, and the expression of endoplasmic reticulum (ER) stress-related genes (XBP-1, BiP, ATF-4, and CHOP) after exposure to Cd for 24 h. We found that Cd decreased cell viability in a concentration-dependent manner, with a median lethal concentration (LC₅₀) of 11 µM. DNA damage induction was evidenced by upregulation of the level of γ-H2AX. Furthermore, Cd induced G0/G1 phase cell cycle arrest and apoptosis in a dose-dependent manner and upregulated the mRNA levels of ER stress biomarker genes (XBP-1, BiP, ATF4, and CHOP). Taken together, our results showed that Cd induced cytotoxicity and DNA damage in HaCaT cells, eventually resulting in cell cycle arrest in the G0/G1 phase and apoptosis. In addition, ER stress may be involved in Cd-induced HaCaT apoptosis. Our data imply the importance of reducing Cd pollution in the environment to reduce its adverse impacts on human skin.

Effects of Nickel at Environmentally Relevant Concentrations on Human Corneal Epithelial Cells: Oxidative Damage and Cellular Apoptosis

Nickel (Ni) is ubiquitous in the environment and evidence has suggested that Ni can cause ocular surface inflammation, especially in fine particulate matter and personal products. Continuous daily exposure to Ni-containing dust may adversely impact the human cornea, whereas the underlying mechanism of this phenomenon remains not fully understood. Here, human corneal epithelial cells (HCEC) were employed to analyze the toxicity of Ni via detections of cell morphology, cell viability, reactive oxygen species production, cell apoptosis rate, and apoptotic gene expression levels after exposure for 24 h to uncover the damage of Ni to the cornea. A concentration-dependent inhibition of HCECs’ viability and growth was observed. In particular, Ni at 100 μM significantly decreased cell viability to 76%, and many cells displayed an abnormal shape and even induced oxidative damage of HCEC by increasing ROS to 1.2 times, and further led to higher apoptosis (24%), evidenced by up-regulation of apoptotic genes Caspase-8, Caspase-9, NF-κB, IL-1β, and Caspase-3, posing a risk of dry eye. Our study suggested that Ni induces apoptosis of HCEC through oxidative damage. Therefore, Ni pollution should be comprehensively considered in health risks or toxic effects on the ocular surface.

Inhalation Bioaccessibility and Risk Assessment of Metals in PM2.5 Based on a Multiple-Path Particle Dosimetry Model in the Smelting District of Northeast China

PM2.5 can deposit and partially dissolve in the pulmonary region. In order to be consistent with the reality of the pulmonary region and avoid overestimating the inhalation human health risk, the bioaccessibility of PM2.5 heavy metals and the deposition fraction (DF) urgently needs to be considered. This paper simulates the bioaccessibility of PM2.5 heavy metals in acidic intracellular and neutral extracellular deposition environments by simulating lung fluid. The multipath particle dosimetry model was used to simulate DF of PM2.5. According to the exposure assessment method of the U.S. Environmental Protection Agency, the inhalation exposure dose threshold was calculated, and the human health risk with different inhalation exposure doses was compared. The bioaccessibility of heavy metals is 12.1−36.2%. The total DF of PM2.5 in adults was higher than that in children, and children were higher than adults in the pulmonary region, and gradually decreased with age. The inhalation exposure dose threshold is 0.04−14.2 mg·kg−1·day−1 for the non-carcinogenic exposure dose and 0.007−0.043 mg·kg−1·day−1 for the carcinogenic exposure dose. Cd and Pb in PM2.5 in the study area have a non-carcinogenic risk to human health (hazard index < 1), and Cd has no or a potential carcinogenic risk to human health. A revised inhalation health risk assessment may avoid overestimation.

The Effects of Vitamins and Micronutrients on Helicobacter pylori Pathogenicity, Survival, and Eradication: A Crosstalk between Micronutrients and Immune System

Helicobacter pylori as a class I carcinogen is correlated with a variety of severe gastroduodenal diseases; therefore, H. pylori eradication has become a priority to prevent gastric carcinogenesis. However, due to the emergence and spread of multidrug and single drug resistance mechanisms in H. pylori, as well as serious side effects of currently used antibiotic interventions, achieving successful H. pylori eradication has become exceedingly difficult. Recent studies expressed the intention of seeking novel strategies to improve H. pylori management and reduce the risk of H. pylori-associated intestinal and extragastrointestinal disorders. For which, vitamin supplementation has been demonstrated in many studies to have a tight interaction with H. pylori infection, either directly through the regulation of the host inflammatory pathways or indirectly by promoting the host immune response. On the other hand, H. pylori infection is reported to result in micronutrient malabsorption or deficiency. Furthermore, serum levels of particular micronutrients, especially vitamin D, are inversely correlated to the risk of H. pylori infection and eradication failure. Accordingly, vitamin supplementation might increase the efficiency of H. pylori eradication and reduce the risk of drug-related adverse effects. Therefore, this review aims at highlighting the regulatory role of micronutrients in H. pylori-induced host immune response and their potential capacity, as intrinsic antioxidants, for reducing oxidative stress and inflammation. We also discuss the uncovered mechanisms underlying the molecular and serological interactions between micronutrients and H. pylori infection to present a perspective for innovative in vitro investigations, as well as novel clinical implications.

Cadmium and Cadmium/BDE (47 or 209) Exposure Affect Mitochondrial Function, DNA Damage/Repair Mechanisms and Barrier Integrity in Airway Epithelial Cells

Heavy metals and Brominated diphenyl ether flame-retardants (BDEs) often coexist in the environment and are capable of inducing injury, cytotoxicity or genotoxicity in human epithelial cells of the lung. We studied the effects of single Cadmium chloride (CdCl2) or CdCl2/BDE (47 or 209) mixtures in airway epithelial cells, using A549 cell line cultured at submerged conditions and air–liquid interface (ALI) (an in vitro model described as physiologically relevant in vivo-like). We evaluated cell viability, oxidative stress, apoptosis, DNA damage/repair (Comet assay, γH2AX phosphorylation ser139), mitochondrial redox balance (NOX-4, Nrf2 and TFAM) and cell barrier integrity (TEER, ZO-1, Claudin-1, E-cadherin-1) in A549 cells exposed to CdCl2 (1 nM to 10 µM), or to CdCl2 (100 nM)/BDEs (47 or 209) (100 nM). CdCl2 (10 μM) reduced cell viability and increased apoptosis. CdCl2 (100 nM) significantly affected DNA-damage/repair (Olive Tail length production), γH2AX phosphorylation and oxidative stress (ROS/JC-1 production) in submerged cell cultures. CdCl2 (100 nM) decreased viability, TEER, ZO-1, Claudin-1 and E-cadherin-1 mRNA expression, and Nrf2 and TFAM while increased NOX-4, in ALI culture of cells. In both cell culture approaches, the cells stimulated with Cadmium/BDEs mixtures did not show a significant increase in the effects observed in the cells treated with CdCl2 alone. CdCl2 inhalation might exert cytotoxicity and genotoxicity, playing a pivotal role in the uncontrolled oxidative stress, damaging DNA and gene expression in airway epithelial cells. No additional or synergistic adverse effects of CdCl2/BDEs mixture were observed in comparison to CdCl2 alone in lung epithelium.