Associations of metal mixtures with metabolic-associated fatty liver disease and non-alcoholic fatty liver disease: NHANES 2003-2018

The association between endocrine disrupting chemicals and nonalcoholic fatty liver disease: A systematic review and meta-analysis

Nonalcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver disease worldwide. Epidemiological studies have reported that exposure of the population to environmental endocrine-disrupting chemicals (EDCs) is associated with NAFLD. However, EDCs are of different types, and there are inconsistencies in the relevant evidence and descriptions, which have not been systematically summarized so far. Therefore, this study aimed to determine the association between population exposure to EDCs and NAFLD. Three databases, including PubMed, Web of science, and Embase were searched, and 27 articles were included in this study. Methodological quality, heterogeneity, and publication bias of the included studies were assessed using the Newcastle-Ottawa scale, I2 statistics, Begg's test, and Egger's test. The estimated effect sizes of the included studies were pooled and evaluated using the random-effects model (I2 > 50 %) and the fixed-effects model ( I2 < 50 %). The pooled-estimate effect sizes showed that population exposure to Phthalates (PAEs) (OR = 1.18, 95 % CI:1.03-1.34), cadmium (Cd) (OR = 1.37, 95 % CI:1.09-1.72), and bisphenol A (OR = 1.43, 95 % CI:1.24-1.65) were positively correlated with the risk of NAFLD. Exposure to mercury (OR =1.46, 95 % CI:1.17-1.84) and Cd increased the risk of "elevated alanine aminotransferase". On the contrary, no significant association was identified between perfluoroalkyl substances (OR =0.99, 95 % CI:0.93-1.06) and NAFLD. However, female exposure to perfluorooctanoic acid (OR =1.82, 95 % CI:1.01-3.26) led to a higher risk of NAFLD than male exposure. In conclusion, this study revealed that EDCs were risk factors for NAFLD. Nonetheless, the sensitivity analysis results of some of the meta-analyses were not stable and demonstrated high heterogeneity. The evidence for these associations is limited, and more large-scale population-based studies are required to confirm these findings.

Associations of Urinary Heavy Metal Mixtures with High Remnant Cholesterol among US Adults: Evidence from the National Health and Nutrition Examination Survey (1998-2018)

The main objective of our study is to explore the associations between combined exposure to urinary heavy metals and high remnant cholesterol (HRC), a known cardiovascular risk factor. Utilizing data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018, we conducted a cross-sectional analysis of 5690 participants, assessing urinary concentrations of ten heavy metals. Ten heavy metals in urine were measured by inductively coupled plasma mass spectrometry (ICP-MS). Fasting residual cholesterol ≥0.8 mmol/L was defined as HRC (using blood samples). Statistical analyses included weighted multivariable logistic regression, weighted quantile sum (WQS) regression, quantile g-computation (qgcomp), and Bayesian kernel machine regression (BKMR) to evaluate the associations of heavy metal exposure with HRC. Stratified analyses based on individual characteristics were also conducted. Multivariable logistic regression found that the four metals (OR Q4 vs. Q1: 1.33, 95% CI: 1.01-1.75 for barium (Ba); OR Q4 vs. Q1: 1.50, 95% CI: 1.16-1.94 for cadmium (Cd); OR Q4 vs. Q1: 1.52, 95% CI: 1.15-2.01 for mercury (Hg); OR Q4 vs. Q1: 1.35, 95% CI: 1.06-1.73 for lead (Pb)) were positively correlated with the elevated risk of HRC after adjusting for covariates. In addition, all three mixed models, including WQS (OR: 1.25; 95% CI: 1.07-1.46), qgcomp (OR: 1.17; 95% CI: 1.03-1.34), and BKMR, consistently showed a significant positive correlation between co-exposure to heavy metal mixtures and HRC, with Ba and Cd being the main contributors within the mixture. These associations were more pronounced in younger adults (20 to 59 years), males, and those with a higher body mass index status (≥25 kg/m2). Our findings reveal a significant relationship between exposure to the mixture of heavy metals and HRC among US adults, with Ba and Cd being the major contributors to the mixture's overall effect. Public health efforts aimed at reducing heavy metal exposure can help prevent HRC and, in turn, cardiovascular disease.

The biomedical application of inorganic metal nanoparticles in aging and aging-associated diseases

Aging and aging-associated diseases (AAD), including neurodegenerative disease, cancer, cardiovascular diseases, and diabetes, are inevitable process. With the gradual improvement of life style, life expectancy is gradually extended. However, the extended lifespan has not reduced the incidence of disease, and most elderly people are in ill-health state in their later years. Hence, understanding aging and AAD are significant for reducing the burden of the elderly. Inorganic metal nanoparticles (IMNPs) predominantly include gold, silver, iron, zinc, titanium, thallium, platinum, cerium, copper NPs, which has been widely used to prevent and treat aging and AAD due to their superior properties (essential metal ions for human body, easily synthesis and modification, magnetism). Therefore, a systematic review of common morphological alternations of senescent cells, altered genes and signal pathways in aging and AAD, and biomedical applications of IMNPs in aging and AAD is crucial for the further research and development of IMNPs in aging and AAD. This review focus on the existing research on cellular senescence, aging and AAD, as well as the applications of IMNPs in aging and AAD in the past decade. This review aims to provide cutting-edge knowledge involved with aging and AAD, the application of IMNPs in aging and AAD to promote the biomedical application of IMNPs in aging and AAD.

Investigating the impact of elevated urinary trace elements on non-alcoholic fatty liver disease using vibration-controlled transient elastography

Introduction

Non-alcoholic fatty liver disease (NAFLD) is a global public health concern. However, limited data are available on urinary trace elements and NAFLD caused by various exposure factors. This study aimed to investigate the relationship between the presence of 16 trace elements in urine and NAFLD using data from the National Health and Nutrition Examination Survey (NHANES).

Methods

By utilizing the NHANES data from 2017 to 2018, 1613 participants who fulfilled the research criteria were identified from the initial pool of 2979 participants with available urine trace element detection data. Among them, 706 individuals had been diagnosed with NAFLD based on a coefficient of attenuation parameter (CAP) value of at least 274 db/m, determined using vibration-controlled transient elastography (VCTE); whereas the remaining 907 participants were classified as non-NAFLD. The data obtained were used to construct univariate and multivariate logistic regression models and restricted cubic spline models (RCS) analyses.

Results

The presence of arsenic, iodine, barium, cesium, molybdenum, lead, tin, and tungsten in the urine of individuals with NAFLD showed a positive correlation with the likelihood of developing NAFLD. The risk of NAFLD had a non-linear dose-dependent relationship with urinary iodine, molybdenum, barium, and cesium. NAFLD was also associated with elevated levels of barium and cesium in urine, which were identified as significant risk factors.

Conclusion

These findings suggest a positive association between exposure to trace elements in the urine and the risk of NAFLD. Specifically, urinary barium and cesium appeared to have the greatest impact on the risk of NAFLD. These results provide novel insights into the diagnosis and treatment of NAFLD.

Sustained effects of developmental exposure to inorganic arsenic on hepatic gsto2 expression and mating success in zebrafish

The impacts of exposure to the pervasive environmental toxicant, inorganic arsenic (iAs), on human and fish health are well characterized and several lines of evidence suggest that some impacts can manifest years after exposure cessation. Using a developmental exposure protocol whereby zebrafish embryos were exposed to 0.5 and 1.5 mM iAs from 4-120 hours post fertilization (hpf) and then removed, we investigated the sustained effects of iAs on gene expression in the liver, survival, reproductive success, and susceptibility to iAs toxicity in the subsequent generation. Persistent exposure to iAs during development had substantial effects on the hepatic transcriptome, with 23% of all expressed genes significantly changed following developmental exposure. The gsto2 gene is involved in iAs metabolism and this gene was significantly downregulated in female livers 9 months after iAs was removed. Developmental exposure to 1.5 mM iAs, but not 0.5 mM, decreased survival by over 50% at 3 months of age. Adults that were developmentally exposed to 0.5 mM iAs had reduced mating success, but their offspring had no differences in observable aspects of development or their susceptibility to iAs toxicity. This demonstrates that developmental exposure of zebrafish to iAs reduces long-term survival, reproductive success and causes sustained changes to gsto2 expression in the liver.

Mediating Role of Liver Dysfunction in the Association between Arsenic Exposure and Diabetes in Chinese Adults: A Nationwide Cross-Sectional Study of China National Human Biomonitoring (CNHBM) 2017-2018

Inconsistent results have been reported regarding the association between low-to-moderate arsenic (As) exposure and diabetes. The effect of liver dysfunction on As-induced diabetes remains unclear. The cross-sectional study included 10,574 adults from 2017-2018 China National Human Biomonitoring. Urinary total As (TAs) levels were analyzed as markers of As exposure. Generalized linear mixed models and restricted cubic splines models were used to examine the relationships among TAs levels, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) concentrations, and diabetes prevalence. Mediating analysis was performed to assess whether liver dysfunction mediated the association between TAs and diabetes. Overall, the OR (95% CI) of diabetes in participants in the second, third, and fourth quartiles of TAs were 1.08 (0.88, 1.33), 1.17 (0.94, 1.45), and 1.52 (1.22, 1.90), respectively, in the fully adjusted models compared with those in the lowest quartile. Serum ALT was positively associated with TAs and diabetes. Additionally, mediation analyses showed that ALT mediated 4.32% of the association between TAs and diabetes in the overall population and 8.86% in the population without alcohol consumption in the past year. This study suggested that alleviating the hepatotoxicity of As could have implications for both diabetes and liver disease.

Role of Mitochondrial Reactive Oxygen Species-Mediated Chaperone-Mediated Autophagy and Lipophagy in Baicalin and N-Acetylcysteine Mitigation of Cadmium-Induced Lipid Accumulation in Liver

Cadmium (Cd) is a major health concern globally and can accumulate and cause damage in the liver for which there is no approved treatment. Baicalin and N-acetylcysteine (NAC) have been found to have protective effects against a variety of liver injuries, but it is not clear whether their combined use is effective in preventing and treating Cd-induced lipid accumulation. The study found that Cd increased the production of mitochondrial reactive oxygen species (mROS) and elevated the level of chaperone-mediated autophagy (CMA). Interestingly, mROS-mediated CMA exacerbates the Cd-induced inhibition of lipophagy. Baicalin and NAC counteracted inhibition of lipophagy by attenuating Cd-induced CMA, suggesting an interplay between CMA elevation, mitochondrial destruction, and mROS formation. Maintaining the stability of mitochondrial structure and function is essential for alleviating Cd-induced lipid accumulation in the liver. Choline is an essential component of the mitochondrial membrane and is responsible for maintaining its structure and function. Mitochondrial transcriptional factor A (TFAM) is involved in mitochondrial DNA transcriptional activation and replication. Our study revealed that the combination of baicalin and NAC can regulate choline metabolism through TFAM and thereby maintain mitochondrial structure and functionality. In summary, the combination of baicalin and NAC plays a more beneficial role in alleviating Cd-induced lipid accumulation than the drug alone, and the combination of baicalin and NAC can stabilize mitochondrial structure and function and inhibit mROS-mediated CMA through TFAM-choline, thereby promoting lipophagy to alleviate Cd-induced lipid accumulation.

Hepato-renal toxicity of low dose metal(oid)s mixture in real-life risk simulation in rats: Effects on Nrf2/HO-1 signalling and redox status

The understanding that humans are exposed to a low level of toxic metals and metalloids in their lifetime has resulted in a shift in scientific and regulatory perspectives from the traditional evaluation of single metal toxicity to complex mixtures, relevant to real-life exposure. Therefore, the aim of this study was to examine the impact of real-life, 90-days exposure to mixture of toxic metal(oid)s, Cd, Pb, Ni, Cr, As and Hg, on the nuclear factor erythroid 2-related factor 2 and hemoxygenase-1 (Nrf2/HO-1) signalling and redox status by assessing total sulfhydryl groups (SH), glutathione (GSH), superoxide dismutase activity (SOD), malondialdehyde (MDA), and ischemia modified albumin (IMA) in the liver and kidney of Wistar rats. Animals (20 males and 20 females) were randomized in 2 control and 6 treated groups that received by oral gavage mixture of metal(oid)s solutions in doses that reflect blood metal(oid) levels determined in previous human biomonitoring study as benchmark dose (F/M _BMD), median (F/M _MED), and 95th percentile (F/M _95). Our results have shown that metal(oid)s mixture impaired the activation of the Nrf2/HO-1 pathway in the kidney and liver of male rats and kidney of female rats, followed by depletion of GSH levels in males. Additionally, in males elevated levels of IMA in the liver were observed, while in both genders increased MDA levels were observed in the kidney. Interestingly, the effects were more pronounced in male than in female rats. This study is among the first that examined hepato-renal toxic mechanisms of real-life metal mixture exposure, while our results might be of immense importance for assessing the risk of exposure to mixtures of toxic substances.

Dissecting the role of cadmium, lead, arsenic, and mercury in non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

The objective of the present study was to review the existing epidemiological and laboratory findings supporting the role of toxic metal exposure in non-alcoholic fatty liver disease (NAFLD). The existing epidemiological studies demonstrate that cadmium (Cd), lead (Pb), arsenic (As), and mercury (Hg) exposure was associated both with an increased risk of NAFLD and altered biochemical markers of liver injury. Laboratory studies demonstrated that metal exposure induces hepatic lipid accumulation resulting from activation of lipogenesis and inhibition of fatty acid β-oxidation due to up-regulation of sterol regulatory element-binding protein 1 (SREBP-1), carbohydrate response element binding protein (ChREBP), peroxisome proliferator-activated receptor γ (PPARγ), and down-regulation of PPARα. Other metabolic pathways involved in this effect may include activation of reactive oxygen species (ROS)/extracellular signal-regulated kinase (ERK) and inhibition of AMP-activated protein kinase (AMPK) signaling. The mechanisms of hepatocyte damage during development of metal-induced hepatic steatosis were shown to involve oxidative stress, endoplasmic reticulum stress, pyroptosis, ferroptosis, and dysregulation of autophagy. Induction of inflammatory response contributing to progression of NAFLD to non-alcoholic steatohepatitis (NASH) upon toxic metal exposure was shown to be mediated by up-regulation of nuclear factor κB (NF-κB) and activation of NRLP3 inflammasome. Moreover, epigenetic effects of the metals, as well as their effect on gut microbiota and gut wall integrity were also shown to mediate their role in NAFLD development. Despite being demonstrated for Cd, Pb, and As, the contribution of these mechanisms into Hg-induced NAFLD is yet to be estimated. Therefore, further studies are required to clarify the intimate mechanisms underlying the relationship between heavy metal and metalloid exposure and NAFLD/NASH to reveal the potential targets for treatment and prevention of metal-induced NAFLD.

Associations of 10 trace element levels in the whole blood with risk of three types of obesity in the elderly

BACKGROUND

Currently, over 2 billion people worldwide suffer from obesity, which poses a serious health risk. More and more attention is being given to the effects of trace elements on obesity in recent years. Synergistic or antagonistic interactions among these elements can adversely or positively impact human health. However, epidemiological evidence on the relationship between trace element exposure levels and obesity has been inconclusive.

METHODS

Baseline data of 994 participants from the Cohort of Elderly Health and Environment Controllable Factors were used in the present study. ICP-MS was used to measure the concentrations of 10 trace elements in the whole blood of the older population. Binary logistic regression, restricted cubic splines (RCS) models, and Bayesian kernel machine regression (BKMR) models were employed to assess single, nonlinear, and mixed relationships between 10 trace element levels and three types of obesity based on body mass index (BMI), waist circumference (WC), and body fat percentage (BFP) in the elderly.

RESULTS

Based on BMI, WC and BFP, 51.8% of the included old population were defined as general overweight/obesity, 67.1% as abdominal obesity, and 36.2% as having slightly high/high BFP. After multivariable adjustment, compared with the lowest tertile, the highest tertile of blood selenium (Se) concentration was associated with an increased risk of all three types of obesity. Additionally, compared with the lowest tertile, higher tertiles of strontium (Sr) concentrations were associated with a lower risk of general overweight/obesity and having slightly high/high BFP, and the highest tertile of barium (Ba) was associated with a lower risk of having slightly high BFP, while higher tertiles of arsenic (As) concentrations were associated with an increased risk of having slightly high/high BFP, and the highest tertile of manganese (Mn) was associated with a higher risk of abdominal obesity. BKMR analyses showed a strong linear positive association between Se and three types of obesity. Higher blood levels of trace element mixture were associated with increased obesity risks in a dose-response pattern, with Se having the highest value of the posterior inclusion probability (PIP) within the mixture.

CONCLUSIONS

In this study, we found higher Se levels were associated with an elevated risk of obesity and high levels of Ba, Pb and Cr were associated with a decreased risk of obesity. Studies with larger samples are needed to confirm these findings.

Association between mixed urinary metal exposure and liver function: analysis of NHANES data

Metals have been reported to affect liver functions; however, the association between mixed metal exposure in the urine and liver functions remains unclear. The present study analyzed data from the National Health and Nutrition Examination Survey (NHANES) program collected in 2005-2018. Weighted multiple linear regression and Bayesian kernel machine regression (BKMR) were used to explore the relationship between mixed urinary metal contents and liver function tests (LFTs). A total of 8158 participants were analyzed in this study. Multiple methods suggested that cadmium (Cd) was significantly positively related to LFTs, while cobalt (Co) was negatively related to LFTs. Meanwhile, some other metals showed a significant relationship with some indicators of LFTs. Urine metal is related to LFTs, with Cd and Co content changes being closely related to LFTs. The metal in urine may represent a marker for predicting liver dysfunction. Further studies are needed to verify this hypothesis.

Joint effects of phenol, chlorophenol pesticide, phthalate, and polycyclic aromatic hydrocarbon on bone mineral density: comparison of four statistical models

Exposure to phenols, phthalates, pesticides, and polycyclic aromatic hydrocarbons (PAHs) can harm the skeleton. However, data about the joint effects of these chemicals' mixture on bone health are limited. The final analysis involved 6766 participants aged over 20 years recruited from the National Health and Nutrition Examination Survey. Generalized linear regression, weighted quantile sum (WQS) regression, Bayesian kernel machine regression (BKMR), and quantile g-computation (qgcomp) were performed to investigate the association of the urinary levels of chemicals (three phenols, two chlorophenol pesticides, nine phthalates, and six polycyclic aromatic hydrocarbon [PAH] metabolites) with bone mineral density (BMD) measurements and osteoporosis (OP) risk. Generalized linear regression identified that benzophenone-3, 2,4-dichlorophenol, mono-n-butyl phthalate, 1-napthol, 3-fluorene, 2-fluorene, and 1-phenanthrene were significantly associated with lower BMD and increased OP risk. The WQS index was negatively associated with total femur, femoral neck, and lumbar spine vertebra 1 (L1) BMD among all the participants, with corresponding β (95% confidence interval) values of -0.028 g/cm2 (-0.040, -0.017), -0.015 g/cm2 (-0.025, -0.004), and -0.018 g/cm2 (-0.033, -0.003). In the BKMR analysis, the overall effect of the mixture was significantly associated with femoral neck BMD among males and OP risk among females. The qgcomp model found a significant association between co-exposure and L1 BMD among all the participants and among males. Our study presents compelling epidemiological evidence that co-exposure to phenols, chlorophenol pesticides, phthalates, and PAHs is associated with reduced BMD and elevated OP risk. It provides epidemiologic evidence for the detrimental effects of these chemicals on bone health.

Sex, Nutrition, and NAFLD: Relevance of Environmental Pollution

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease and represents an increasing public health issue given the limited treatment options and its association with several other metabolic and inflammatory disorders. The epidemic, still growing prevalence of NAFLD worldwide cannot be merely explained by changes in diet and lifestyle that occurred in the last few decades, nor from their association with genetic and epigenetic risk factors. It is conceivable that environmental pollutants, which act as endocrine and metabolic disruptors, may contribute to the spreading of this pathology due to their ability to enter the food chain and be ingested through contaminated food and water. Given the strict interplay between nutrients and the regulation of hepatic metabolism and reproductive functions in females, pollutant-induced metabolic dysfunctions may be of particular relevance for the female liver, dampening sex differences in NAFLD prevalence. Dietary intake of environmental pollutants can be particularly detrimental during gestation, when endocrine-disrupting chemicals may interfere with the programming of liver metabolism, accounting for the developmental origin of NAFLD in offspring. This review summarizes cause-effect evidence between environmental pollutants and increased incidence of NAFLD and emphasizes the need for further studies in this field.