Lead exposure affects inflammatory mediators, total and differential white blood cells in sensitized guinea pigs during and after sensitization

Heavy Metal Pollution in the Environment and Its Impact on Health: Exploring Green Technology for Remediation

Along with expanding urbanization and industrialization, environmental pollution which negatively affects the surroundings, has been rising quickly. As a result, induces heavy metal contamination which poses a serious threat to living organisms of aquatic and soil ecosystems. Therefore, they are a need to ameliorate the effects cost by cost pollution on the environment. In this review, we explore methods employed to mitigate the effects caused by heavy metals on the environment. Many techniques employed to manage environmental pollution are tedious and very costly, necessitating the use of alternative management strategies to resolve this challenge. In this concept, bioremediation is viewed as a future technique, due to its environmental friendliness and cost-effective measures aligned with sustainable or climate-smart agriculture to manage contaminants in the environment. The technique involves the use of living entities such as bacteria, fungi, and plants to deteriorate toxic substances from the rhizosphere. Currently, bioremediation is thought to be the most practical, dependable, environmentally benign, and long-lasting solution. Although bioremediation involves different techniques, they are still a need to find the most efficient method for removing toxic substances from the environment. This review focuses on the origins of heavy metal pollution, delves into cost-effective and green technological approaches for eliminating heavy metal pollutants from the environment, and discusses the impact of these pollutants on human health.

Association between Exposure to Selected Heavy Metals and Blood Eosinophil Counts in Asthmatic Adults: Results from NHANES 2011-2018

(1) Background: Heavy metals are widely used and dispersed in the environment and people's daily routines. Many studies have reported an association between heavy metal exposure and asthma. Blood eosinophils play a crucial role in the occurrence, progression, and treatment of asthma. However, there have thus far been few studies that aimed to explore the effects of heavy metal exposure on blood eosinophil counts in adults with asthma. Our study aims to discuss the association between metal exposure and blood eosinophil counts among asthmatic adults. (2) Methods: A total of 2026 asthmatic individuals were involved in our research from NHANES with metal exposure, blood eosinophils, and other covariates among the American population. A regression model, the XGBoost algorithm, and a generalized linear model (GAM) were used to explore the potential correlation. Furthermore, we conducted a stratified analysis to determine high-risk populations. (3) Results: The multivariate regression analysis indicated that concentrations of blood Pb (log per 1 mg/L; coefficient β, 25.39; p = 0.010) were positively associated with blood eosinophil counts. However, the associations between blood cadmium, mercury, selenium, manganese, and blood eosinophil counts were not statistically significant. We used stratified analysis to determine the high-risk group regarding Pb exposure. Pb was identified as the most vital variable influencing blood eosinophils through the XGBoost algorithm. We also used GAM to observe the linear relationship between the blood Pb concentrations and blood eosinophil counts. (4) Conclusions: The study demonstrated that blood Pb was positively correlated with blood eosinophil counts among asthmatic adults. We suggested that long-time Pb exposure as a risk factor might be correlated with the immune system disorder of asthmatic adults and affect the development, exacerbation, and treatment of asthma.

Global Trends in Mortality and Burden of Stroke Attributable to Lead Exposure From 1990 to 2019

Background

Lead exposure is an important risk factor for stroke. However, the latest global spatiotemporal patterns of lead exposure-related stroke burden were unclear. In this study, we assessed this topic.

Methods

The data were obtained from the Global Burden of Disease Study (2019). The estimated annual percentage change (EAPC) was estimated to evaluate the temporal trends of the age-standardized mortality and disability-adjusted life years (DALYs) rates (ASMR and ASDR) of stroke attributable to lead exposure.

Results

In 2019, the numbers of global stroke deaths and DALYs attributable to lead exposure were 305.27 and 6738.78 thousand, respectively. The corresponding ASMR and ASDR were highest in males, the elderly population, low and middle-income countries, and the intracerebral hemorrhage subtype. From 1990 to 2019, the ASMR and ASDR of global stroke attributable to lead exposure decreased [ASMR: EAPC = −1.34, 95% confidence interval (CI): (−1.57, −1.10); ASDR: EAPC = −1.74, 95% CI: (−1.95, −1.52)], especially in females, the high-income countries, and the subarachnoid hemorrhage subtype.

Conclusion

This study emphasizes the importance of continued implementation of lead exposure prevention strategies and improved high-efficiency treatment and stroke acute health care, especially in low and middle-income countries.

Lead exposure does not affect baseline and induced innate immunity in quails

Lead (Pb) is one of the most common metals found in ecosystems in elevated concentrations derived mainly from anthropogenic activities. Pb toxicity is of special concern in birds due to its capacity for bioaccumulation in the liver, bones, and kidneys causing physiological disruptions. Such disruptions can be lethal in a few days after Pb acute intoxication and they are associated with several million deaths of birds. Moreover, Pb may work as an immunosuppressant as it affects the cell-mediated and humoral immune responses, including components of the acute-phase response (APR). We (1) examined the effects of Pb contamination on the innate immune system, body mass, and food intake of Japanese quails (Coturnix coturnix japonica), and (2) evaluated the effects of Pb on its APR after exposing the animals to Pb acetate in drinkable water during 7 days. We found that Pb contamination increased the number of circulating white blood cells (WBCs), but no effect was found on body mass, food intake, the heterophil/lymphocyte (H/L) ratio, and haptoglobin (Hp) concentration. When Pb-exposed birds were injected with lipopolysaccharide from Escherichia coli to activate the APR, they had a negative body mass ratio, reduced food intake, and increased the number of WBCs, the H/L ratio, and the Hp concentration. We conclude that Pb exposure at this dose did not affect baseline values of the constitutive response and that it did not affect the APR of quails, but commend for further studies testing the effect of different Pb doses.

Blood Lead, Systemic Inflammation, and Blood Pressure: Exploring Associations and Mediation Effects in Workers Exposed to Lead

Relationships of lead exposure with blood pressure and blood lead with inflammation have been previously established yet, but the conclusions are still controversial. The objective of our study was to investigate the role of systemic inflammation in the relationships between blood lead concentration and blood pressure. We quantified the levels of blood lead and white blood cell count in 505 lead-exposed workers with 842 observations. Associations between blood lead, white blood cell count, and blood pressure were evaluated by using linear mixed models. We further performed mediation analysis to investigate the role of white blood cell count in the associations between blood lead concentration and blood pressure. We observed that each 1% increase of blood lead levels was significantly positively associated with a 0.9%, 1.7%, and 1.1% increases in systolic blood pressure, white blood cell count, and blood platelet count, respectively. Also, we found that the levels of white blood cell count were positively correlated with diastolic blood pressure and systolic blood pressure in a dose-response manner. Mediation analysis showed that the levels of white blood cell significantly mediated the associations between concentration of blood lead and systolic blood pressure. Collectively, our findings suggest that blood lead was positively associated with systolic blood pressure and that systemic inflammation might play a key role in this association.

Toxic Mechanisms of Five Heavy Metals: Mercury, Lead, Chromium, Cadmium, and Arsenic

The industrial activities of the last century have caused massive increases in human exposure to heavy metals. Mercury, lead, chromium, cadmium, and arsenic have been the most common heavy metals that induced human poisonings. Here, we reviewed the mechanistic action of these heavy metals according to the available animal and human studies. Acute or chronic poisonings may occur following exposure through water, air, and food. Bioaccumulation of these heavy metals leads to a diversity of toxic effects on a variety of body tissues and organs. Heavy metals disrupt cellular events including growth, proliferation, differentiation, damage-repairing processes, and apoptosis. Comparison of the mechanisms of action reveals similar pathways for these metals to induce toxicity including ROS generation, weakening of the antioxidant defense, enzyme inactivation, and oxidative stress. On the other hand, some of them have selective binding to specific macromolecules. The interaction of lead with aminolevulinic acid dehydratase and ferrochelatase is within this context. Reactions of other heavy metals with certain proteins were discussed as well. Some toxic metals including chromium, cadmium, and arsenic cause genomic instability. Defects in DNA repair following the induction of oxidative stress and DNA damage by the three metals have been considered as the cause of their carcinogenicity. Even with the current knowledge of hazards of heavy metals, the incidence of poisoning remains considerable and requires preventive and effective treatment. The application of chelation therapy for the management of metal poisoning could be another aspect of heavy metals to be reviewed in the future.

Treadmill exercise ameliorates memory deficits and hippocampal inflammation in ovalbumin-sensitized juvenile rats

The behavioral changes, including spatial learning and memory impairment as well as depressive- and anxiety-like behaviors in an animal model of asthma were demonstrated previously. On the other hand, there is increasing evidence that the anti-inflammatory actions of exercise are related to their neuroprotective properties against different insults in the brain. This study was aimed to explore the effects of moderate treadmill exercise on cognitive deficits and possible anti-inflammatory mechanisms in ovalbumin (OVA)-sensitized rats. The exercise groups were trained to run on the treadmill 30 min/day with an intensity of 12 m/min, 5 days/week for 4 weeks. Animals in the OVA groups were sensitized by two intraperitoneal (i.p.) injections of OVA (10 μg/injection) and challenged with OVA by inhalation during the treadmill running exercise period. Passive avoidance (PA) memory, levels of interleukin (IL)-10 and tumor necrosis factor (TNF)-α in the hippocampus, total and differential white blood cell (WBC) count in the blood as well as pathological changes of the lung were then evaluated. OVA-sensitization was resulted in cognitive deficits in the PA task, along with increased total and differential WBC in blood and TNF-α in the hippocampus. However, exercise ameliorated these changes and increased the IL-10 level in the hippocampus, suggesting that moderate treadmill exercise can improve memory impairment in OVA-sensitized rats due to its anti-inflammatory properties.

Some outcomes and a hypothetical mechanism of combined lead and benzo(a)pyrene intoxication, and its alleviation with a complex of bioprotectors

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Rats were injected repeatedly intraperitoneally with lead acetate and/or benzo(а)pyrene solutions in various dose ratios.

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Under combined exposure the organism load with benzo(а)pyrene was increased while that with its metabolites reduced.

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The genotoxic effect of the combined exposure was higher than that of benzo(a)pyrene alone.

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This effect was inhibited by a complex of antitoxic bioprotectors.

Rats were exposed 3 times a week during 6 weeks to repeated intraperitoneal injections of lead acetate solution in water (Pb) and/or benzo(а)pyrene solution in petrolatum oil (B(а)P) in various dose ratios. Towards the end of the period, the animals developed a moderate subchronic intoxication having some features characteristic of lead effects. The type of combined toxicity estimated with the help of isoboles constructed by the Response Surface Methodology was found to be varied depending on a particular effect, its level, and dose ratio. However, Pb and B(a)P in combination often displayed an additive or even superadditive action. In the group exposed to this combination compared with the group of rats exposed to B(a)P alone, its concentration in the organism was increased while the concentration of some B(a)P oxidative metabolism products was reduced. Such inhibition of B(a)P biotransformation, assumingly associated with impaired heme and, thus, cytochrome P450 synthesis induced by lead intoxication, can serve as an explanation for certain enhancement of the genotoxic effect of B(a)P. This effect was not present in the same combined intoxication if a complex of antitoxic bioprotectors was being administered in the background.

Manifestation of Systemic Toxicity in Rats after a Short-Time Inhalation of Lead Oxide Nanoparticles

Outbred female rats were exposed to inhalation of lead oxide nanoparticle aerosol produced right then and there at a concentration of 1.30 ± 0.10 mg/m³ during 5 days for 4 h a day in a nose-only setup. A control group of rats were sham-exposed in parallel under similar conditions. Even this short-time exposure of a relatively low level was associated with nanoparticles retention demonstrable by transmission electron microscopy in the lungs and the olfactory brain. Some impairments were found in the organism’s status in the exposed group, some of which might be considered lead-specific toxicological outcomes (in particular, increase in reticulocytes proportion, in δ-aminolevulinic acid (δ-ALA) urine excretion, and the arterial hypertension’s development).

Elevated levels of lead exposure and impact on the anti-inflammatory ability of oral sialic acids among preschool children in e-waste areas

The oral health of preschool children in an electronic waste (e-waste) area is susceptible to lead (Pb) exposure increasing the risk of dental caries and causing periodontitis and other oral diseases. The aim of the present study is to investigate the relationship between chronic exposure to Pb and oral anti-inflammatory potential of preschool children. For this analysis, 574 preschool children from 2.5 to 6 years of age were recruited between November and December 2017, in which 357 preschool children were from Guiyu (n = 357), an e-waste-contaminated town, and 217 from Haojiang Shantou. We measured the levels of child blood Pb, salivary sialic acid, serum interleukin-6 (IL-6) and serum tumor necrosis factor-α (TNF-α), and investigated the prevalence of dental caries in deciduous teeth. The medians of blood Pb levels, serum IL-6 and TNF-α were significantly higher in the Guiyu children than in Haojiang children. Concomitantly, salivary sialic acids were lower in the Guiyu children [9.58 (3.97, 18.42) mg/dL] than in Haojiang [17.57 (5.95, 24.23) mg/dL]. Additionally, the prevalence of dental caries in deciduous teeth was significantly higher in the Guiyu children than in Haojiang (62.5% vs. 53.9%). Blood Pb levels were negatively correlated with salivary sialic acids, in which IL-6 played as a mediator of the association between blood Pb levels and saliva sialic acid concentrations according to the mediation model. To our knowledge, this is the first report on the potential association between chronic Pb exposure and the anti-inflammatory ability of oral sialic acids among preschool children. These results suggest that the chronic Pb exposure can reduce salivary sialic acid levels, attenuate oral anti-inflammatory potential and increase the potential risk of dental caries in deciduous teeth among preschool children in an e-waste site.

Further verification of some postulates of the combined toxicity theory: New animal experimental data on separate and joint adverse effects of lead and cadmium

Outbred male rats were repeatedly injected intraperitoneally two-level sub-lethal doses of lead acetate and/or cadmium chloride solutions 3 times a week during 6 weeks. The animals developed explicit, even if moderate, subchronic intoxication characterized by a large number of indices, both common to both metals (including increased DNA fragmentation coefficient) and lead-specific. Special attention was paid to hemodynamic and electrocardiographic effects. The combined action of lead and cadmium was modeled with the help of the Response Surface Methodology to obtain additional support for the previously substantiated postulates of combined toxicity's typological ambiguity. This is dependent on which particular effect comes under consideration, on its level, and on the acting dose ratio. For one and the same toxic combination, the type of combined toxic action can vary from synergistic to contra-directional. In particular, the actions of lead and cadmium on blood pressure were found to be opposite in direction. Furthermore, it is shown once again that the systemic toxic effects of a metal combination, its in vivo genotoxicity included, can be more or less attenuated by background administration of a theoretically justified composition of biologically active agents.

Further analysis of rat myocardium contractility changes associated with a subchronic lead intoxication

A moderate subchronic lead intoxication was observed in male rats after repeated intraperitoneal injections of lead acetate. Right ventricular trabeculae and papillary muscles were isolated for in vitro studying of the contraction-relaxation cycle under isotonic and physiological loading. The contractile function of the myocardium was also assessed by measuring the velocity of thin filament movement over myosin. Lead intoxication led in papillary muscles to a decrease in the maximal rate of isotonic shortening for all afterloads and a decrease in the thin filament sliding velocity. Papillary muscles from lead-exposed rats displayed marked changes in most of the main characteristics of afterload contraction-relaxation cycles, but in trabeculae these changes were less pronounced. The reported changes were attenuated to some extent in rats treated with a Ca-containing bioprotector. The amount of work produced by both types of heart muscle preparations was not changed by lead. Only in papillary muscles the load-dependent relaxation index was significantly increased in the lead-treated groups. Thus subchronic lead intoxication affects the peak rate of force development and relaxation properties of cardiac muscle contracting in isotonic/physiological regimes rather than the total amount of mechanical work, which may reflect adaptive changes in the myocardial function under decreased contractility.

The effect of environmental lead exposure on human health and the contribution of inflammatory mechanisms, a review

Lead (Pb) pollution has been considered as a major threat for human health due to induction of inflammatory cascades in various tissues. The aim of present review is to summarize the literature on the effects of lead exposure on respiratory, neurologic, digestive, cardiovascular and urinary disorders and the role of inflammation as an underlying mechanism for these effects. Various databases such as ISI Web of Knowledge, Medline, PubMed, Scopus, Google Scholar and Iran Medex, were searched from 1970 to November 2017 to gather the required articles using appropriate keywords such as lead, respiratory disorders, neurologic disorders, digestive disorders, cardiovascular disorders, urinary disorders and inflammation. Disorders of various body systems and the role of inflammation due to lead exposure has been proven by various studies. These studies indicate that lead exposure may cause respiratory, neurologic, digestive, cardiovascular and urinary diseases. The results were also indicated the increased inflammatory cells and mediators due to lead exposure including cytokines and chemokines due to lead exposure which suggested to be the cause various organ disorders.

Oxidative stress in opium users after using lead-adulterated opium: The role of genetic polymorphism

Use of lead-adulterated opium has become one of the major sources of lead poisoning in Iran. This study was designed to assess clinical effects and oxidative stress and its association with GSTM1, GSTT1, NQO1, and ALAD genes polymorphisms and blood lead level (BLL) in lead-adulterated opium users. The oxidative stress status in 192 opium users with lead poisoning symptoms measured and compared with 102 healthy individuals. Gluthatione S-transferase (GST)-M1 and -T1 genes deletion, NQO1 rs1800566, and δ-aminolevulinic acid dehydratase (ALAD) rs1800435 polymorphisms were determined using PCR and PCR-RFLP. The relation between the polymorphisms, BLL, and oxidative stress parameters were analysed using multivariate linear regressions. The common symptoms of lead toxicity were gastrointestinal and neurologic complications. Oxidative stress was significantly higher in opium addicts and lipid peroxidation significantly correlated with BLL. There was significant association between ALAD rs1800435 and BLL, and the BLL was significantly lower in the patients with ALAD 1-2 genotype. Use of lead-adulterated opium causes high frequency of lead toxicity symptoms, hematological and biochemical abnormalities, and oxidative stress which are associated with BLL. Route of opioid use and the polymorphism of rs1800435 in ALAD gene are the major determinants of BLL in lead-adulterated opium users.

Effects of subchronic lead intoxication of rats on the myocardium contractility

Outbred male rats were repeatedly injected IP with sub-lethal doses of lead acetate 3 times a week during 5 weeks. They developed an explicit, even if moderate, lead intoxication characterized by typical hematological and some other features. The next day after the last injection the heart of each animal was excised, and the trabecules and papillary muscles from the right ventricle were used for modeling in vitro isometric (with varying starting length of the preparation) regimes of the contraction-relaxation cycle with different preloads. Several well-established parameters of this model were found changed compared with the preparations taken from the hearts of healthy control rats. Background in vivo calcium treatment attenuated both systemic and cardiotoxic effects of lead to an extent. We show for the first time that subchronic intoxication with lead caused myocardial preparations in a wide range of lengths to respond by a decrease in the time and speed parameters of the isometric contraction while maintaining its amplitude and by a decrease in the passive stiffness of trabecules. The responses of the various heart structures are outlined, and the isomyosin ratio is shown to have shifted towards the slow isoform. Mechanistic and toxicological inferences from the results are discussed.

Lead (Pb) Exposure Enhances Expression of Factors Associated with Inflammation

The human immune system is constantly exposed to xenobiotics and pathogens from the environment. Although the mechanisms underlying their influence have already been at least partially recognized, the effects of some factors, such as lead (Pb), still need to be clarified. The results of many studies indicate that Pb has a negative effect on the immune system, and in our review, we summarize the most recent evidence that Pb can promote inflammatory response. We also discuss possible molecular and biochemical mechanisms of its proinflammatory action, including the influence of Pb on cytokine metabolism (interleukins IL-2, IL-4, IL-8, IL-1b, IL-6), interferon gamma (IFNγ), and tumor necrosis factor alpha (TNF-α); the activity and expression of enzymes involved in the inflammatory process (cyclooxygenases); and the effect on selected acute phase proteins: C-reactive protein (CRP), haptoglobin, and ceruloplasmin. We also discuss the influence of Pb on the immune system cells (T and B lymphocytes, macrophages, Langerhans cells) and the secretion of IgA, IgE, IgG, histamine, and endothelin.