The sex-specific effects of blood lead, mercury, and cadmium levels on hepatic steatosis and fibrosis: Korean nationwide cross-sectional study

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.

Joint and interactive effects of metal mixtures on liver damage: Epidemiological evidence from repeated-measures study

BACKGROUND

The impact of heavy metals on liver function has been examined in numerous epidemiological studies. However, these findings lack consistency and longitudinal validation.

METHODS

In this study, we conducted three follow-up surveys with 426 participants from Northeast China. Blood and urine samples were collected, along with questionnaire information. Urine samples were analyzed for concentrations of four metals (chromium [Cr], cadmium [Cd], lead [Pb], and manganese [Mn]), while blood samples were used to measure five liver function indicators (alanine aminotransferase [ALT], aspartate aminotransferase [AST], albumin [ALB], globulin [GLB], and total protein [TP]). We utilized a linear mixed-effects model (LME) to explore the association between individual heavy metal exposure and liver function. Joint effects of metal mixtures were investigated using quantile g-computation and Bayesian kernel machine regression (BKMR). Furthermore, we employed BKMR and Marginal Effect models to examine the interaction effects between metals on liver function.

RESULTS

The LME results demonstrated a significant association between urinary heavy metals (Cr, Cd, Pb, and Mn) and liver function markers. BKMR results indicated positive associations between heavy metal mixtures and ALT, AST, and GLB, and negative associations with ALB and TP, which were consistent with the g-comp results. Synergistic effects were observed between Cd-Cr on ALT, Mn-Cr and Cr-Pb on ALB, while an antagonistic effect was found between Mn-Pb and Mn-Cd on ALB. Additionally, synergistic effects were observed between Mn-Cr on GLB and Cd-Cr on TP. Furthermore, a three-way antagonistic effect of Mn-Pb-Cr on ALB was identified.

CONCLUSION

Exposure to heavy metals (Cr, Cd, Mn, Pb) is associated with liver function markers, potentially leading to liver damage. Moreover, there are joint and interaction effects among these metals, which warrant further investigation at both the population and mechanistic levels.

Selenium and zinc alleviate hepatotoxicity induced by heavy metal mixture (cadmium, mercury, lead and arsenic) via attenuation of inflammo-oxidant pathways

Heavy metals (HM) are believed to be injurious to humans. Man is exposed to them on daily basis unknowingly, with no acceptable protocol to manage its deleterious effects. These metals occur as mixture of chemicals with varying concentrations in our atmosphere. There are growing calls for the use of essential metals in mitigating the injurious effects induced by heavy metals exposure to man; therefore, the aim of this study was to evaluate the protective effects of essential metals (Zinc and Selenium) in a mixture of heavy metal toxicity. In this study, except for negative controls, all other groups were treated with lead (PbCl2 , 20 mg kg-1 ); cadmium (CdCl2 , 1.61 mg kg-1 ); mercury (HgCl2 , 0.40 mg kg-1 ), and arsenic (NaAsO3, 10 mg kg-1 ) that were formed in distilled water. Pb, Cd, As, and Hg were administered as mixtures to 35, 6 weeks old rats weighing between 80 to 100 g for 60 days. Group I served as normal control without treatment, group II positive control received HM mixture, while groups III to V received HMM with Zn, Se, and Zn + Se respectively. Animal and liver weights, HM accumulation in the liver, food intake (FI), water intake (WI), liver function test, malondialdehyde (MDA), and inflammatory/transcription factor/apoptosis markers were checked. Also, antioxidant enzymes, and histological studies were carried out. Metal mixture accumulated in the liver and caused toxicities which were ameliorated by Zn and Se administration. HM caused significant decrease in FI, WI and distorted the level of liver enzymes, lipid peroxidation, inflammatory markers, antioxidants and architecture of the liver. Co administration with Zn or Se or both reversed the distortions. This study lays credence to the evolving research on the public health implications of low dose metal mixtures and the possible ameliorative properties of Zn and Se.

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.

Association Between Non-alcoholic Fatty Liver Disease and Heavy Metal Exposure: a Systematic Review

Non-alcoholic fatty liver disease (NAFLD) is a debilitating disease with adverse effects including cirrhosis and hepatocellular carcinoma. Heavy metals can cause severe dysfunction in different body organs including the liver. This review offers the study regarding the positive or negative association between heavy metals exposure and non-alcoholic fatty liver disease. The method used in this study is a systematic review based on searching in the PubMed, Scopus, and Science direct databases with the keywords of fatty liver, non-alcohol fatty liver, heavy metal, mercury, cadmium, arsenic, chromium, thallium, lead, iron, zinc, and nickel. There were 2200 articles searched in databases, and after assessment, 28 articles were selected. Positive association is established between arsenic, cadmium, iron, lead, mercury, and fatty liver disease. A negative relationship is found between zinc, copper, and progressive fatty liver disease. Furthermore, laboratory methods for NAFLD diagnosis were examined according to the obtained manuscripts. Among the different diagnostic methods, magnetic resonance imaging (MRI) is a sensitive method.

Relationship of individual and mixed urinary metals exposure with liver function in the China National Human Biomonitoring (CNHBM) of Zhejiang Province

BACKGROUND

Heavy metals have been reported to affect liver function. However, there is currently little and inconsistent knowledge about the effects of combined and individual urinary metals on specific parameters of liver function in the general population. Therefore, this study aimed to investigate their associations.

METHODS

This study involved 807 general population from the China National Human Biomonitoring of Zhejiang Province 2017-2018. Concentrations of urinary metals, including Chromium (Cr), Cobalt (Co), Nickle (Ni), Arsenic (As), Selenium (Se), Molybdenum (Mo), Cadmium (Cd), Thallium (Tl) and Lead (Pb) were measured. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein (TP), albumin (ALB), direct bilirubin (DBIL), total bilirubin (TBIL) as liver function biomarkers. Multivariable linear regression and weighted quantile sum (WQS) regression were employed to explore the associations of urinary metals with liver function biomarkers. Subgroup analysis stratified by gender and age, excluding smokers and drinkers for sensitivity analysis.

RESULTS

Both statistical models indicated that urinary metals were positively associated with ALT and AST, while negatively with TP, ALB, DBIL and TBIL. In the WQS analysis, each quartile increase in the ln-transformed levels of metal mixtures was associated with 4.11 IU/L (95% CI: 1.07, 7.15) higher ALT and 3.00 IU/L (95% CI: 1.75, 4.25) higher AST, as well as, with 0.67 g/L (95% CI: 1.24, -0.11) lower TP, 0.74 g/L (95% CI: 1.09, -0.39) lower ALB, 0.38 μmol/L (95% CI: 0.67, -0.09) lower DBIL, and 1.56 μmol/L (95% CI: 2.22, -0.90) lower TBIL. The association between urinary metals and ALT was primarily driven by Cd (55.8%), Cr contributed the most to the association with AST (20.2%) and TBIL (45.2%), while the association with TP was primarily driven by Ni (38.2%), the association with ALB was primarily driven by As (32.8%), and the association with DBIL was primarily driven by Pb (30.9%). The associations between urinary metals and liver function might differ by sex and age.

CONCLUSION

Urinary metals were significantly associated with liver function parameters. Further studies are required to clarify the relationship between heavy metals and liver function.

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.

Association between serum ferritin and liver stiffness in adults aged ≥20 years: A cross-sectional study based on NHANES

The importance of serum ferritin has been demonstrated in many liver diseases, but its relationship with liver stiffness remains unclear. The objective of this study was to investigate the association between serum ferritin levels and participants' liver stiffness measurement (LSM) in the United States population. We conducted a screening of participants from National Health and Nutrition Examination Survey (NHANES) 2017.1 to 2020.3 to ensure that participants included in this study had complete serum ferritin and LSM information. Association between the independent variable (serum ferritin) and the dependent variable (LSM) was investigated by multiple linear regression and subgroup analysis was performed to identify sensitive individuals, and we subsequently assessed whether there was a non-linear relationship between the 2 using smoothed curve fitting and threshold effect models. The final 7143 participants were included in this study. There was a positive association between participants' serum ferritin concentration and LSM, with an effect value of (β = 0.0007, 95% confidence interval (CI): 0.0002-0.0011) in the all-adjusted model. The smoothing curve and threshold effect models indicated a non-linear positive correlation between serum ferritin and LSM, which was more pronounced when serum ferritin concentration exceeded 440 ng/mL. Subsequent subgroup analysis showed that this positive correlation was more pronounced in males (β = 0.0007, 95% CI: 0.0001-0.0012), age >60 years (β = 0.00015, 95% CI: 0.0007-0.0023), black participants (β = 0.00018, 95% CI: 0.0009-0.0026), and participants with body mass index (BMI) <25 kg/m2 (β = 0.00012, 95% CI: 0.0005-0.0020). In U.S. adults, there was a positive correlation between serum ferritin levels and liver stiffness, which was more pronounced when serum ferritin exceeded 440 ng/mL. Our study suggested that regular serum ferritin testing would be beneficial in monitoring changes in liver stiffness. Male, age >60 years, black participants, and those with a BMI < 25 kg/m2 should be of greater consideration.

Effect of cadmium exposure on body composition deterioration: A propensity score-matched cohort study

This propensity score-matched cohort study investigated the effects of blood cadmium (Cd) levels on body composition. Body composition was assessed by multifrequency bioelectrical impedance analysis and categorized into three groups: metabolically healthy obesity (MHO), adiposity obesity (AO), and sarcopenic obesity (SO). At baseline, 85 and 101 participants had MHO and AO, respectively (mean age, 51 ± 7 years; male-to-female ratio, 1.0:1.3). During the 14-year follow-up, the body composition of 40 MHO and 6 AO participants deteriorated to AO and SO, respectively. The incidence of AO and SO differed according to age, sex, and blood Cd level. High blood Cd level increased the risk of body composition deterioration, particularly among those aged 60-69 years (hazard ratio [HR] = 2.14), women (HR = 1.46), and those with AO at baseline (HR = 1.63; all p < 0.05). Cd exposure deteriorates body composition in older and female individuals, particularly from AO to SO.

Associations of blood metals with liver function: Analysis of NHANES from 2011 to 2018

BACKGROUND

Heavy metals have been reported to affect liver function. However, there is currently little and inconsistent knowledge about the effects of combined and individual blood metals on specific parameters of liver function in the general population. Hence, this study aimed to elucidate their associations.

METHODS

Data from National Health and Nutrition Examination Survey (NHANES) 2011-2018 were used in this cross-sectional study. Multivariate linear, and a quantile-based g-computation (qgcomp) were applied to explore the associations between blood metals [mercury (Hg), manganese (Mn), lead (Pb), cadmium (Cd), selenium (Se)], alone and in combination, and liver function parameters [alanine transaminase (ALT), aspartate transaminase (AST), ALT/AST, alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT) and serum total bilirubin (TBIL)].

RESULTS

A total of 15,328 were included. Multivariate linear models indicated that liver function was significantly associated with blood heavy metals. The most significant relationship was found between Se and AST (β 5.09, 95%CI (3.28,6.91), p＜0.001), Mn and ALT (β 1.24, 95%CI (0.57, 1.91), p＜0.001). Furthermore, the qgcomp analysis showed that the combination of five blood metals was positively associated with AST, ALT, GGT, TBIL and HSI. Cd contributed the most to the correlation of AST (weight = 0.447), Se contributed the most to the association of ALT (weight = 0.438) and HSI (weight = 0.570), Pb contributed the most to the association of GGT (weight = 0.421) and Hg contributed the most to the correlation of TBIL (weight = 0.331).

CONCLUSIONS

Blood heavy metal levels were significantly associated with liver function parameters. Further studies are required to clarify the relationship between heavy metals and liver function.

Blood and urine manganese exposure in non-alcoholic fatty liver disease and advanced liver fibrosis: an observational study

Manganese was the key activator of biological enzymes-mediated metabolic diseases (Mets)-associated pathophysiological process. Non-alcoholic fatty liver disease (NAFLD), which was the hepatic manifestation of Mets, development remained a mystery. We aimed to explore the association between blood/urine manganese exposure and NAFLD and liver fibrosis diagnosed by vibration-controlled transient elastography (VCTE). All data were extracted from National Health and Nutrition Examination Survey database (2017-2018). A total of 3580 participants with blood manganese data were enrolled and divided into four groups according to the quartile of blood manganese exposure level. In multiple logistic regression models, the higher blood manganese exposure level (groups 2, 3, and 4) had a significant positive association with NAFLD (β = 1.58, 1.30, and 1.69). In subgroup analysis, the main inversely correlation between blood manganese and NAFLD was found in participants with normal/high body mass index and high blood manganese exposure level. Moreover, in 1179 participants with urine manganese data, urine manganese exposure level presented as significantly associated with advanced liver fibrosis in models 1 and 2 (β = 2.00 and 2.02). This study showed that manganese exposure level was positively associated with NAFLD and advanced liver fibrosis among the US population. We suggested that manganese exposure level was a biomarker of the development of NAFLD.

Effects of Environmental Cadmium Exposure on the Liver in Korean Adults: Cross-Sectional and Longitudinal Studies

Cadmium (Cd) is a ubiquitous environmental pollutant with an exceptionally long biological half-life. The liver is a major organ for Cd metabolism, but the toxicity of Cd is unclear. This study sought to determine whether blood Cd (BCd) level (representing recent exposure [months] to Cd) was associated with liver function in Korean adults, both cross-sectionally and longitudinally. The baseline cross-sectional study involved 2,086 adults (male: 908, female: 1,178) in 2010 - 2011, and 503 of them (male: 207, female: 296) were followed up in 2014 - 2015. BCd was measured by graphite-furnace atomic absorption spectrometry, and liver function indices (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and γ-glutamyltransferase [GGT]) were determined. Liver damage was defined as an abnormal elevation of more than one liver function index. The geometric mean of BCd (1.07 μg/L) was higher in females than in males (1.16 vs. 0.96 μg/L). Liver function indices increased significantly in a dose-dependent manner according to the BCd levels, except for ALT in males, and were higher in males than in females. BCd level was also associated with the risk of liver damage in both sexes. No significant changes in BCd were observed between baseline and follow-up. The liver function indices in 2014 - 2015 were comparable to those in 2010 - 2011 in males, while ALT and GGT were significantly increased in 2014 - 2015 compared to 2010 - 2011 in females with relatively high BCd. These findings suggest that even a low level of environmental Cd exposure, short- and long-term, may affect liver function, and females appear more susceptible than males.

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

Objective

The hepatotoxicity of exposure to a single heavy metal has been examined in previous studies. However, there is limited evidence on the association between heavy metals mixture and non-alcoholic fatty liver disease (NAFLD) and metabolic-associated fatty liver disease (MAFLD). This study aims to investigate the associations of 13 urinary metals, individually and jointly, with NAFLD, MAFLD, and MAFLD components.

Methods

This study included 5,548 adults from the National Health and Nutrition Examination Survey (NHANES) 2003-2018. Binary logistic regression was used to explore the associations between individual metal exposures and MAFLD, NAFLD, and MAFLD components. Bayesian kernel machine regression (BKMR) and Quantile-based g-computation (QGC) were used to investigate the association of metal mixture exposure with these outcomes.

Results

In single metal analysis, increased levels of arsenic [OR 1.09 (95%CI 1.03-1.16)], dimethylarsinic acid [1.17 (95%CI 1.07-1.27)], barium [1.22 (95%CI 1.14-1.30)], cobalt [1.22 (95%CI 1.11-1.34)], cesium [1.35 (95%CI 1.18-1.54)], molybdenum [1.45 (95%CI 1.30-1.62)], antimony [1.18 (95%CI 1.08-1.29)], thallium [1.49 (95%CI 1.33-1.67)], and tungsten [1.23 (95%CI 1.15-1.32)] were significantly associated with MAFLD risk after adjusting for potential covariates. The results for NAFLD were similar to those for MAFLD, except for arsenic, which was insignificantly associated with NAFLD. In mixture analysis, the overall metal mixture was positively associated with MAFLD, NAFLD, and MAFLD components, including obesity/overweight, diabetes, and metabolic dysfunction. In both BKMR and QGC models, thallium, molybdenum, tungsten, and barium mainly contributed to the positive association with MAFLD.

Conclusion

Our study indicated that exposure to heavy metals, individually or cumulatively, was positively associated with NAFLD, MAFLD, and MAFLD components, including obesity/overweight, diabetes, and metabolic dysfunction. Additional research is needed to validate these findings in longitudinal settings.

Associations of Dietary and Plasma Copper Levels with Liver Function in a Chinese Population

The potential mechanisms underlying the association between copper (Cu) exposure and impaired liver function are unclear. This study aimed to investigate the potential associations of dietary Cu intake and plasma Cu levels with liver function biomarkers. A cross-sectional study was performed to assess liver function biomarkers-namely, levels of total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL), alanine transaminase (ALT), and aspartate transaminase (AST)-in 2376 subjects in Guangxi, China. Dietary Cu intake was determined from a food frequency questionnaire containing 109 common foods. Plasma Cu concentrations were determined by inductively coupled plasma‒mass spectrometry. Multiple linear regression and multivariate restricted cubic splines (RCS) were used to evaluate the correlations of plasma Cu levels and dietary Cu levels with liver function biomarkers. The covariate-adjusted results of the linear regression analysis showed that plasma Cu levels were significantly negatively correlated with serum IBIL (β =  - 0.37), DBIL (β =  - 0.22), and TBIL levels (β =  - 0.32) (all p < 0.05), and dietary Cu was negatively correlated with serum AST levels (β =  - 0.12, p < 0.05). The RCS analysis further indicated a negative linear relationship between dietary Cu levels and AST levels. In summary, our results suggested that the plasma Cu level is associated with serum bilirubin levels and that dietary Cu intake is associated with serum AST levels. Further studies are needed to validate these associations and elucidate the underlying mechanisms.

Effects of chemical mixtures on liver function biomarkers in the Korean adult population: thresholds and molecular mechanisms for non-alcoholic fatty liver disease involved

There is a scarcity of research on the effects of a mixture of chemicals on liver function biomarkers and non-alcoholic fatty liver disease (NAFLD) indices, including FSI, HIS, and FBI-4. Thus, we aimed to explore whether there is an association between chemical mixtures, including 26 chemicals found in blood and urine, liver function biomarkers, and non-alcoholic fatty liver disease (NAFLD) indices in Korean adults. The effects of exposure to chemical mixtures on liver function biomarkers and NAFLD indices were investigated using linear regression models, weighted quantile sum (WQS) regression, quantile g-computation (qgcomp), and Bayesian kernel machine regression (BKMR) among 3669 adults. In silico toxicogenomic data-mining, we evaluated molecular mechanisms associated with NAFLD, including pathways, diseases, genes, miRNAs, and biological processes. The linear regression models showed blood or urine Hg levels were the most important factors associated with AST, ALT, GGT, FSI, and HSI levels, and significant trends were observed for these chemical quartiles (p < 0.01). The WQS index was significantly associated with ALT, GGT, FSI, and HSI. The qgcomp index also found an association between chemicals and AST, ALT, GGT, and FSI. In the BKMR model, the overall effect of the mixture was significantly related to ALT, GGT, FSI, and HSI. In silico analysis, we found mixed chemicals interacted with the CYP1A2 gene and were associated with NAFLD. Seventy-eight percent of interactions were identified as physical interactions in the CYP1A2 gene related to NAFLD. Transcription factor regulation in adipogenesis and lipid metabolic processes are fundamental molecular mechanisms that could be influenced by NAFLD-related mixed chemicals. Cutoff thresholds for chemical exposure levels associated with liver function indicators and NAFLD indices were also reported. The strongest interactions and expression of miRNAs involved in NAFLD development were also identified.

Association of blood manganese, selenium with steatosis, fibrosis in the National Health and Nutrition Examination Survey, 2017-18

BACKGROUND & AIMS

Chronic liver disease is a growing health burden worldwide. Chronic metal exposures may be associated with non-alcoholic fatty liver disease (NAFLD). We aimed to evaluate the association of blood cadmium (Cd), mercury (Hg), lead (Pb), manganese (Mn), and selenium (Se) with two hallmark features of NAFLD: liver steatosis and fibrosis in the general U.S.

METHODS

We analyzed transient liver elastography data from participants of the National Health and Nutrition Examination Survey (NHANES) 2017-18, using ordinal logistic regression analyses to evaluate the cross-sectional association between blood metal concentrations and clinical stages of steatosis and fibrosis. We applied survey weights, strata, and primary sampling units and analyses were conducted using the R survey package.

RESULTS

4,154 participants were included. Median (IQR) for blood Mn and blood Se were 9.28 (7.48-11.39) and 191.08 (176.55-207.16) μg/L, respectively. Per interquartile range increase of natural log transformed blood Mn, the adjusted odds ratio (OR) (95% CI) was 1.59 (1.13-2.23) for a higher grade of steatosis and 1.16 (0.67-2.00) for liver fibrosis. The corresponding OR for steatosis was 2.00 (1.24-3.24) and 2.14 (1.04-4.42) in Black and Mexican American participants, respectively. The corresponding OR for liver fibrosis was 2.96 (1.42-6.17) for females. Per interquartile range increase of natural log transformed blood Se, the adjusted OR was 2.25 (1.30-3.89) for steatosis but 0.31 (0.13-0.72) for liver fibrosis. The inverse association of blood Se with liver fibrosis was also observed in males and White participants. Blood Cd, Hg, and Pb were not associated with liver steatosis and fibrosis in fully-adjusted models overall.

CONCLUSIONS

In NHANES 2017-18, higher blood Mn was positively associated with liver steatosis, and higher Se was positively associated with liver steatosis but negatively associated with liver fibrosis. Longitudinal studies are needed to examine the association of Mn and Se with fibrosis progression.

Cadmium, lead, and mercury mixtures interact with non-alcoholic fatty liver diseases

There is a scarcity of studies on the interactions between heavy metals and non-alcoholic fatty liver disease (NAFLD). Using a variety of statistical approaches, we investigated the impact of three common heavy metals on liver enzymes and NAFLD markers in a Korean adult population. We observed that cadmium, mercury, and lead all demonstrated positive correlations with liver enzymes and NAFLD indices. Our findings were mostly robust in secondary analysis, which included three novel mixture modeling approaches (WQS, qgcomp, and BKMR) as well as in silico investigation of molecular mechanisms (genes, miRNAs, biological processes, pathways, and illnesses). The 16 genes interacted with a mixture of heavy metals, which was linked to the development of NAFLD. Co-expression was discovered in nearly half of the interactions between the 18 NAFLD-linked genes. Key molecular pathways implicated in the pathogenesis of NAFLD generated by the heavy metal combination include activated oxidative stress, altered lipid metabolism, and increased cytokines and inflammatory response. Heavy metal exposure levels were related to liver enzymes and NAFLD indices, and cutoff criteria were revealed. More studies are needed to validate our findings and gain knowledge about the effects of chronic combined heavy metal exposure on adult and child liver function and the likelihood of developing NAFLD. To reduce the occurrence of NAFLD, early preventative and regulatory actions (half-yearly screening of workers at high-risk facilities; water filtration; avoiding excessive amounts of seafood, etc.) should be taken.

Long-Term Sex-Specific Effects of Cadmium Exposure on Osteoporosis and Bone Density: A 10-Year Community-Based Cohort Study

This study explored the long-term effects of cadmium (Cd) exposure on osteoporosis incidence and bone mineral density (BMD). This retrospective cohort study included men aged ≥50 years and post-menopausal women from the 2001−2002 Korea Genome and Epidemiology Study. Participants previously diagnosed with osteoporosis were excluded. Blood Cd concentrations were measured and categorized as <0.5, 0.5−1.0, and >1.0 μg/L. BMD was measured using quantitative ultrasound. Osteoporosis was diagnosed when the T-score was ≤−2.5. Confounders that affect exposure and outcome were controlled. Osteoporosis incidence and differences in BMD (ΔBMD) were assessed until 2012. The osteoporosis incidence among 243 participants who were followed up for an average of 6.3 years was 22.2%. In all the participants, a dose−response relationship was observed between blood Cd and incident osteoporosis and ΔBMD (both p-for-trend < 0.01). After adjusting for age, sex, smoking, physical activity, body mass index, creatinine, and baseline BMD, a blood Cd concentration of >1.0 μg/L was an independent risk factor for incident osteoporosis and decrements in ΔBMD. In women, blood Cd concentrations of >0.5 μg/L increased the risk for osteoporosis. Exposure to Cd prospectively increases the risk for osteoporosis and decrements of ΔBMD, particularly in women, even in lower doses of Cd.

Chronic exposure to low-dose cadmium facilitated nonalcoholic steatohepatitis in mice by suppressing fatty acid desaturation

Exposure to cadmium (Cd), a toxic metal, is epidemiologically linked to nonalcoholic steatohepatitis (NASH) in humans. However, the role of Cd in NASH remains to be fully elucidated. This study employed a novel murine NASH model to investigate the effects of chronic low-dose Cd on hepatic pathology and its underlying mechanisms. NASH is characterized by lipid accumulation, extensive cell death, and persistent inflammation in the liver. We found that treatment with Cd in drinking water (10 mg/L) for 6 or 12 weeks significantly boosted hepatic fat deposition, increased hepatocyte destruction, and amplified inflammatory responses in mice, confirming that low-dose Cd can facilitate NASH development in vivo. Mechanistically, chronic Cd exposure reshaped the hepatic transcriptional landscape, with PPAR-mediated fatty acid metabolic pathways being the most significantly altered. In particular, Cd repressed fatty acid desaturation, leading to the accumulation of saturated fatty acids whose lipotoxicity exacerbated cell death and, consequently, inflammatory activation. In summary, we validated the causal effects of chronic low-dose Cd on NASH in vivo and identified the fatty acid desaturation program as a novel target for Cd to instigate hepatopathological alterations.

Lead, mercury, and cadmium exposures are associated with obesity but not with diabetes mellitus: Korean National Environmental Health Survey (KoNEHS) 2015-2017

BACKGROUND

Associations of heavy metal exposures with obesity and obesity-related traits have been suggested, while those with nonalcoholic fatty liver disease (NAFLD) and diabetes mellitus (DM) are often inconsistent.

METHODS

This study included 3787 adults aged ≥19 years who participated in the Korean National Environmental Health Survey 2015-2017, and investigated the association of toxic heavy metals with metabolic diseases. Lead (Pb), mercury (Hg), and cadmium (Cd) were measured either in urine (uHg, uCd) or total blood (bPb, bHg). Body mass index (BMI) was calculated, and DM cases were identified through a self-answered medication history. Hepatic Steatosis Index (HSI) as a surrogating index of NAFLD, was calculated using hepatic enzyme measurements, including aspartate aminotransferase (AST) and alanine aminotransferase (ALT).

RESULTS

Adults in the highest quartile of bPb, bHg, and uHg showed significantly elevated odds of obesity (BMI ≥25 kg/m²), compared to the lowest quartile (OR 1.58 for bPb, 1.92 for bHg, and 1.81 for uHg). HSI was positively correlated with bHg, uHg, and uCd concentrations. The odds of NAFLD (HSI ≥36) were also increased with increasing quartile of bHg, uHg, and uCd concentrations. For DM, bPb showed a significant negative association, while bHg and uCd exhibited non-monotonic and inconclusive associations.

CONCLUSIONS

Among the general adult population of Korea, both Pb and Hg exposures were associated with an increased risk of obesity. In addition, both Hg and Cd exposures were associated with increased odds of NAFLD. These metals, however, were not associated with an increased risk of DM.

Role of mitochondrial dysfunction and PINK1/Parkin-mediated mitophagy in Cd-induced hepatic lipid accumulation in chicken embryos

The present study was performed to investigate the effects of Cd exposure on lipid metabolism and mitochondrial dysfunction and to explore the role of mitophagy in Cd-induced dysregulation of lipid metabolism in chicken embryo liver tissues and hepatocytes. To this end, seven-day-old chicken embryos were exposed to different concentrations of Cd for 7 days, and primary chicken embryo hepatocytes were treated with Cd at four different concentrations for 6 h. Furthermore, the mitophagy inhibitor cyclosporine A (CsA) was used to investigate the role of mitophagy in Cd-induced disruption of lipid metabolism. Lipid accumulation, the expression levels of genes involved in lipid metabolism, mitochondrial dysfunction, and mitophagy were measured. The results demonstrated that Cd exposure increases hepatic triglyceride (TG) accumulation and the expression levels of lipogenic genes while decreasing those of lipolytic genes. Furthermore, Cd exposure was observed to alter mitochondrial morphology in terms of reduced size, excessive mitochondrial damage, and the formation of mitophagosomes. The co-localization of lysosome-associated membrane glycoprotein 2 and LC3 puncta was significantly increased in primary chicken embryo hepatocytes after Cd exposure. Moreover, Cd exposure increased LC3, PINK1, and Parkin protein expression levels. CsA effectively alleviated Cd-induced mitochondrial dysfunction, blocked mitochondrial membrane potential collapse, and suppressed PINK1/Parkin-mediated mitophagy. Furthermore, CsA treatment reversed the Cd-induced TG accumulation in liver tissues but further increased it in hepatocytes. Taken together, our findings demonstrate (for the first time) the importance of mitochondrial dysfunction and mitophagy via the PINK1/Parkin pathway in Cd-induced disruption of lipid metabolism.

Transcription profiling of cadmium-exposed livers reveals alteration of lipid metabolism and predisposition to hepatic steatosis

1. Cadmium (Cd) is a ubiquitous environmental toxicant that can cause liver steatosis and nonalcoholic fatty liver disease (NAFLD) on long-term exposure.2. Sixteen Sprague Dawley rats were randomly divided into two groups, and were administered normal saline and 5 mg/(kg·d) cadmium chloride by gavage. In vitro, BRL3A cells, a rat normal liver cell line, were treated with different concentrations of Cd to verify the sequencing results.3. The RNA-seq revealed 146 upregulated genes and 127 downregulated genes in the Cd intervention group. The key genes of lipid metabolism were significantly overexpressed, such as Cyp1a1 and Pla2g2d. The GO enrichment analysis showed that the 'sterol biosynthetic process' was the most obvious difference. The KEGG analysis showed that six of the top 10 differential pathways were related to lipid metabolism. The expression of the essential genes in BRL3A was consistent with the sequencing results. The protein-protein interaction (PPI) yielded that Cyp1a1 is in the central region of the differentially expressed gene network.4. The chronic Cd exposure is still an important environmental health problem with a probable tendency to cause NAFLD. It may possibly act by affecting the lipid metabolism in the liver, especially the synthesis and decomposition of unsaturated fatty acids.

Role of Autophagy in Cadmium-Induced Hepatotoxicity and Liver Diseases

Cadmium (Cd) is a toxic pollutant that is associated with several severe human diseases. Cd can be easily absorbed in significant quantities from air contamination/industrial pollution, cigarette smoke, food, and water and primarily affects the liver, kidney, and lungs. Toxic effects of Cd include hepatotoxicity, nephrotoxicity, pulmonary toxicity, and the development of various human cancers. Cd is also involved in the development and progression of fatty liver diseases and hepatocellular carcinoma. Cd affects liver function via modulation of cell survival/proliferation, differentiation, and apoptosis. Moreover, Cd dysregulates hepatic autophagy, an endogenous catabolic process that detoxifies damaged cell organelles or dysfunctional cytosolic proteins through vacuole-mediated sequestration and lysosomal degradation. In this article, we review recent developments and findings regarding the role of Cd in the modulation of hepatotoxicity, autophagic function, and liver diseases at the molecular level.

The Association Between Coffee Consumption and Nonalcoholic Fatty Liver Disease in the South Korean General Population

SCOPE

To identify the cross-sectional and prospective association between coffee consumption and nonalcoholic fatty liver disease (NAFLD) among South Korean adults.

METHODS AND RESULTS

Participants are selected from the Health Examinees study. NAFLD is defined using three non-invasive indexes: fatty liver index (FLI), hepatic steatosis index, and fibrosis-4 calculator (FIB-4). In the cross-sectional analysis, higher habitual coffee consumption is associated with a lower risk for NAFLD, define using the FLI, (men, odds ratio [OR] 0.702; women, OR 0.810) compared with non-consumers. Participants who consumed coffee with sugar and creamer also have a lower risk for NAFLD, defined using the FIB-4, compared with non-coffee-consumers (men, OR 0.739; women, OR 0.807). A prospective analysis indicated that higher coffee consumption is associated with a lower incidence of NAFLD, defined using the FLI, in men (hazard ratio, 0.706). In both men and women, a lower FIB-4 index score is associated with higher coffee consumption regardless of coffee type (all p-value <0.05).

CONCLUSIONS

 Coffee consumption of >3 cups per day has a protective effect against the development of NAFLD to a certain extent, and a negative association is found between coffee consumed with sugar and creamer and the FIB-4 index score in South Korean adults.

Association between Pb, Cd, and Hg Exposure and Liver Injury among Korean Adults

BACKGROUND

Exposure to lead (Pb), cadmium (Cd), and mercury (Hg) has been reported to be associated with liver-related diseases. However, studies examining the association between heavy metal exposure and liver injury in a large population are scant and characterized by inconsistent results. This study aimed to evaluate the association between levels of heavy metal exposure and liver injury in the general population.

METHODS

Data for 2953 participants aged 19 years or more obtained from the Korean National Environmental Health Survey (KoNEHS) Cycle 3 (2015-2017) were used. The associations between levels of blood or urine heavy metals (Pb, Cd, and Hg) and liver function biomarkers [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyl transferase (GGT)] were evaluated using multiple linear regression analysis.

RESULTS

Regarding the blood Pb (BPb), AST was higher in those of the 4th quartile, ALT was higher in those of the 2nd and 4th quartiles, and GGT was higher in those of the 3rd and 4th quartiles than in the 1st quartile. For urinary Cd (UCd), AST was higher in those of the 4th quartile; ALT was higher in those of the 2nd, 3rd, and 4th quartiles; and GGT was higher in the 4th quartile than in the 1st quartile. For the blood Hg (BHg), AST was higher in those of the 2nd and 4th quartile, ALT was higher in those of the 2nd, 3rd, and 4th quartiles; and GGT was higher in those of the 3rd and 4th quartiles than in the 1st quartile. There was no significant difference between urinary Hg (UHg) and liver function markers.

CONCLUSION

Heavy metal exposure showed an association with liver injury among the general adult population in Korea. Further studies are required to clarify the relationship between heavy metals and liver injury.

Association between Blood Mercury Levels and Non-Alcoholic Fatty Liver Disease in Non-Obese Populations: The Korean National Environmental Health Survey (KoNEHS) 2012-2014

Mercury is widely distributed in the environment, and a plausible association between mercury exposure and hepatic damage has been reported. Non-alcoholic fatty liver disease (NAFLD), which comprises a spectrum of liver diseases, has recently been recognized in non-obese subjects. However, there have been no studies on the relationship between internal mercury levels and NAFLD in non-obese individuals. Therefore, we investigated the association between blood mercury levels and NAFLD in non-obese subjects. Cross-sectional data (n = 5919) were obtained from the Korean National Environmental Health Survey (2012–2014). NAFLD was defined using the hepatic steatosis index (HSI). Blood mercury levels were log-transformed and divided into quartiles based on a weighted sample distribution. The association between blood mercury levels and NAFLD was analyzed using a multivariate logistic analysis after body mass index stratification. The geometric mean of blood mercury in the overweight group was significantly higher than that of the non-obese group (p < 0.001). The weighted frequencies of patients with NAFLD based on the HSI were 3.0–7.2% for the non-obese subjects and 52.3–63.2% for the overweight subjects. In the multivariate analysis, blood mercury levels were positively associated with NAFLD for both the overweight and non-obese groups (all p for trend < 0.001). Increased blood mercury levels are closely associated with NAFLD. In particular, mercury could be a risk factor for NAFLD in the non-obese population.