Predicting CO2 production of lactating dairy cows from animal, dietary, and production traits using an international dataset

Automated measurements of the ratio of concentrations of methane and carbon dioxide, [CH4]:[CO2], in breath from individual animals (the so-called "Sniffer-technique") and estimated CO2 production can be used to estimate CH4 production, provided that CO2 production can be reliably calculated. This would allow CH4 production from individual cows to be estimated in large cohorts of cows, whereby ranking of cows according to their CH4 production might become possible and their values could be used for breeding of low CH4 emitting animals. Estimates of CO2 production are typically based on predictions of heat production, which can be calculated from body weight (BW), energy-corrected milk yield, and days of pregnancy. The objectives of the present study were to develop predictions of CO2 production directly from milk production, dietary, and animal variables, and furthermore develop different models to be used for different scenarios, depending on available data. An international data set with 2,244 records from individual lactating cows including CO2 production and associated traits, as dry matter intake (DMI), diet composition, BW, milk production and composition, days in milk and days pregnant, was compiled to constitute the training data set. Research location and experiment nested within research location were included as random intercepts. The method of CO2 production measurement (respiration chamber (RC) or GreenFeed (GF)) was confounded with research location, and therefore excluded from the model. In total, 3 models were developed based on the current training data set: Model 1 ("Best Model"), where all significant traits were included, Model 2 ("On-Farm Model"), where DMI was excluded, and Model 3 ("Reduced On-Farm Model"), where both DMI and BW were excluded. Evaluation on test data sets either with RC data (n = 103), GF data without additives (n = 478) or GF data only including observations where nitrate, 3-nitrooxypropanol (3-NOP), or a combination of nitrate and 3-NOP were fed to the cows (GF+: n = 295), showed good precision of the 3 models, illustrated by low slope bias both in absolute values (-0.22 to 0.097) and in percentage (0.049 to 4.89) of mean square error (MSE). However, the mean bias (MB) indicated systematic over-prediction and under-prediction of CO2 production when the models were evaluated on the GF and the RC test data set, respectively. To address this bias, the 3 models were evaluated on a modified test data set, where the CO2 production (g/d) was adjusted by subtracting (where measurements were obtained by RC) or adding absolute MB (where measurements were obtained by GF) from evaluation of the specific model on RC, GF, and GF+ test data sets. By this modification, the absolute values of MB and MB as percentage of MSE became negligible. In conclusion, the 3 models were precise in predicting CO2 production from lactating dairy cows.

Melatonin mitigates manganese-induced neural damage via modulation of gut microbiota-metabolism in mice

Manganese (Mn), a common environmental and occupational risk factor for Parkinson's disease (PD), can cause central nervous system damage and gastrointestinal dysfunction. The melatonin has been shown to effectively improve neural damage and intestinal microbiota disturbances in animal models. This research investigated the mechanism by which exogenous melatonin prevented Mn-induced neurogenesis impairment and neural damage. Here, we established subchronic Mn-exposed mice model and melatonin supplement tests to evaluate the role of melatonin in alleviating Mn-induced neurogenesis impairment. Mn induced neurogenesis impairment and microglia overactivation, behavioral dysfunction, gut microbiota dysbiosis and serum metabolic disorder in mice. All these events were reversed with the melatonin supplement. The behavioral tests revealed that melatonin group showed approximately 30 % restoration of motor activity. According to quantitative real time polymerase chain reaction (qPCR) results, melatonin group showed remarkable restoration of the expression of dopamine neurons and neurogenesis markers, approximately 46.4 % (TH), 68.4 % (DCX in hippocampus) and 48 % (DCX in striatum), respectively. Interestingly, melatonin increased neurogenesis probably via the gut microbiota and metabolism modulation. The correlation analysis of differentially expressed genes associated with hippocampal neurogenesis indicated that Firmicutes-lipid metabolism might mediate the critical repair role of melatonin in neurogenesis in Mn-exposed mice. In conclusion, exogenous melatonin supplementation can promote neurogenesis, and restore neuron loss and neural function in Mn-exposed mice, and the multi-omics results provide new research ideas for future mechanistic studies.

MTBE exposure may increase the risk of insulin resistance in male gas station workers

Insulin resistance is closely related to many metabolic diseases and has become a serious public health problem worldwide. So, it is crucial to find its environmental pathogenic factors. Methyl tert-butyl ether (MTBE), a widely used unleaded gasoline additive, has been proven to affect glycolipid metabolism. However, results from population studies are lacking. For this purpose, the potential relationships between MTBE exposure and the triglyceride glucose (TyG) index, a useful surrogate marker of insulin resistance, were evaluated using a small-scale occupational population. In this study, 201 participants including occupational and non-occupational MTBE exposure workers were recruited from the Occupational Disease Prevention and Control Hospital of Huaibei, and their health examination information and blood samples with informed consent were collected. The internal exposure levels were assessed by detecting blood MTBE using solid-phase-micro-extraction gas chromatography-mass spectrometry. Then the adjusted linear regression model was used to assess the relationship between MTBE exposure and fasting plasma glucose (FPG), or TyG index. Then, receiver-operating-characteristic (ROC) curves were performed to calculate the optimal cut-off points. Multivariable and hierarchical logistic regression models were used to analyze the impact of MTBE exposure on the risk of insulin resistance. Obvious correlations were observed between blood MTBE levels with TyG index (p = 0.016) and FPG (p = 0.001). Further analysis showed that using the mean of the TyG index (8.77) as a cutoff value had a good effect on reflecting the risk of insulin resistance. Multivariable logistic regression analysis also indicated that MTBE exposure was an independent risk factor for a high TyG index (OR = 1.088, p = 0.038), which indicated that MTBE exposure might be a new environmental pathogenic factor leading to insulin resistance, and MTBE exposure might increase the risk of insulin resistance by independently elevating the TyG index in male gas station workers.

Mediation effect of serum zinc on insulin secretion inhibited by methyl tert-butyl ether in gas station workers

Methyl tert-butyl ether (MTBE), a type of gasoline additive, has been found to affect insulin function and glucose homeostasis in animal experiments, but there is still no epidemiological evidence. Zinc (Zn) is a key regulatory element of insulin secretion and function, and Zn homeostasis can be disrupted by MTBE exposure through inducing oxidative stress. Therefore, we suspected that Zn might be involved and play an important role in the process of insulin secretion inhibited by MTBE exposure. In this study, we recruited 201 male subjects including occupational and non-occupational MTBE exposure from Anhui Province, China in 2019. Serum insulin and functional analog fibroblast growth factor 1 (FGF1) and blood MTBE were detected by Elisa and headspace solid-phase microextraction and gas chromatography-high-resolution mass spectrometry. According to MTBE internal exposure level, the workers were divided into low- and high-exposed groups and found that the serum insulin level in the high-exposed group was significantly lower than that in the low-exposed group (p = 0.003) while fasting plasma glucose (FPG) level increased obviously in the high-exposed group compared to the low-exposed group (p = 0.001). Further analysis showed that MTBE exposure level was positively correlated with FPG level, but negatively correlated with serum insulin level, which suggested that the FPG level increase might be related to the decrease of serum insulin level induced by MTBE exposure. The results of further mediation effect analysis showed that changes in serum zinc levels played a major intermediary role in the process of insulin secretion inhibition and blood glucose elevation caused by MTBE exposure. In addition, a significant negative correlation was found between MTBE exposure and serum Zn level, which might play a strong mediating effect on the inhibition of insulin secretion induced by MTBE exposure. In conclusion, our study provided evidence that MTBE could inhibit insulin secretion and interfere with Zn metabolism in gas station workers for the first time, and found that Zn might play an important mediation effect during the process of inhibiting insulin secretion and interfering with glucose metabolism induced by MTBE exposure.

The Associations between Exposure to Multiple Heavy Metals and Total Immunoglobulin E in U.S. Adults

Immunoglobulin E (IgE) is a type of immunoglobulin, and elevated serum total IgE is often present in allergic diseases. Exposure to environmental heavy metals has been markedly linked to allergic diseases, leading to elevated total IgE levels. However, studies concerning the effects of multiple metal exposures on total IgE levels are limited. Therefore, the current study seeks to explore the correlation between heavy-metal co-exposure and total IgE levels based on the National Health and Nutrition Examination Survey (NHANES, 2005-2006). Participants possessed complete data on total IgE levels, 11 urinary metal concentrations and other covariates. The correlations between 11 metals and total IgE levels were analyzed using multiple linear regression, and total IgE levels were a continuous variable. Total IgE levels exceeding 150 kU/L were considered sensitized. Binary logistic regression analyses were employed to assess the correlation between metal exposure and the occurrence of an allergic state. Then, the association between co-exposure to the 11 metals and total IgE levels or the occurrence of sensitization status was further analyzed by Bayesian kernel machine regression (BKMR), a multi-contaminant model. There were 1429 adults with complete data included. Based on the median concentration, molybdenum (Mo) had the highest concentration (46.60 μg/L), followed by cesium (Cs), barium (Ba), lead (Pb), and mercury (Hg). And the median (interquartile range) for total IgE levels was 43.7 (17.3, 126.0) kU/L. Multiple linear regression results showed that Pb was significantly and positively associated with total IgE levels (β = 0.165; 95% CI: 0.046, 0.284). Binary logistic regression showed a significant positive correlation between urinary Pb (OR: 1.258; 95% CI: 1.052, 1.510) and tungsten (W) (OR: 1.251; 95% CI: 1.082, 1.447). Importantly, the BKMR model found a positive correlation between combined-metal exposure and total IgE levels and the occurrence of sensitization status. The mixed heavy-metal exposure was associated with increased total IgE levels, and this association may be driven primarily by the exposure of Pb and W. This study provides new insights into the relationship between heavy-metal exposure and allergic diseases. More research is needed to confirm these findings.

Single-cell transcriptomics analysis of zebrafish brain reveals adverse effects of manganese on neurogenesis

Manganese (Mn) is considered as an important environmental risk factor for Parkinson's disease. Excessive exposure to Mn can damage various neural cells and affect the neurogenesis, resulting in neurological dysfunction. However, the specific mechanisms of Mn exposure affecting neurogenesis have not been well understood, including compositional changes and heterogeneity of various neural cells. Zebrafish have been successfully used as a neurotoxicity model due to its homology with mammals in several key regions of the brain, as well as its advantages such as small size. We performed single-cell RNA sequencing of zebrafish brains from normal and Mn-exposed groups. Our results suggested that low levels of Mn exposure activated neurogenesis in the zebrafish brain, including promoting the proliferation of neural progenitor cells and differentiation to newborn neurons and oligodendrocytes, while high levels of Mn exposure inhibited neurogenesis and neural function. Mn could affect neurogenesis through specific molecular pathways. In addition, Mn regulated intercellular communication and affected cellular communication in neural cells through specific signaling pathways. Taken together, our study elucidates the cellular composition of the zebrafish brain and adds to the understanding of the mechanisms involved in Mn-induced neurogenesis damage.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

The association of serum neurofilament light chains with early symptoms related to Parkinson's disease: A cross-sectional study

Neurofilament light chains (NfL), released with neural axon injury, is considered as a potential biomarker for Parkinson's disease (PD). The relationship between NfL and PD has been studied mainly in diagnosed patients. Few large-scale studies analyze the association between NfL levels and multiple non-motor symptoms linked to early PD in the general population. Therefore, this study aims to determine the association of NfL with early symptoms of PD, and effectively respond to the development of early symptoms of PD. We examined the relationship between serum NfL and early non-motor symptoms of PD (smell dysfunction, sleep problems, cognitive function) and serum Klotho levels in the general population using data from the 2013-2014 National Health and Nutrition Examination Survey (NHANES). The relationship between serum NfL and early symptoms of PD in 1125 participants was analyzed by multiple linear regression and logistic regression models. The results showed a significant association between serum NfL and early symptoms of PD. There was a significant positive correlation between NfL and smell dysfunction, short sleep and long sleep. There was a significant negative correlation between NfL and Klotho levels and cognitive function test results. Further, we observed gender and age differences in the association of NfL with early symptoms of PD. Our study demonstrate that elevated serum NfL levels are positively associated with an increased risk of early PD-related symptoms, suggesting that serum NfL can be a promising biomarker for early PD.

Effects of graded levels of dietary pomegranate peel on methane and nitrogen losses, and metabolic and health indicators in dairy cows

This study aimed to quantify the effects of dietary inclusion of tannin-rich pomegranate peel (PP) on intake, methane and nitrogen (N) losses, and metabolic and health indicators in dairy cows. Four multiparous, late-lactating Brown Swiss dairy cows (796 kg body weight; 29 kg/d of energy corrected milk yield) were randomly allocated to 3 treatments in a randomized cyclic change-over design with 3 periods, each comprising 14 d of adaptation, 7 d of milk, urine, and feces collection, and 2 d of methane measurements. Treatments were formulated using PP that replaced on a dry matter (DM) basis 0% (control), 5%, and 10% of the basal mixed ration (BMR) consisting of corn and grass silage, alfalfa, and concentrate. Gaseous exchange of the cows was determined in open-circuit respiration chambers. Blood samples were collected on d 15 of each period. Individual feed intake as well as feces and urine excretion were quantified, and representative samples were collected for analyses of nutrients and phenol composition. Milk was analyzed for concentrations of fat, protein, lactose, milk urea N, and fatty acids. Total phenols and antioxidant capacity in milk and plasma were determined. In serum, the concentrations of urea and bilirubin as well as the activities of alanine aminotransferase (ALT), aspartate aminotransferase, glutamate dehydrogenase, alkaline phosphatase, and γ-glutamyl transferase were measured. The data were subjected to ANOVA with the Mixed procedure of SAS, with treatment and period as fixed and animal as random effects. The PP and BMR contained 218 and 3.5 g of total extractable tannins per kg DM, respectively, and thereof 203 and 3.3 g of hydrolyzable tannins. Total DM intake, energy corrected milk, and methane emission (total, yield, and intensity) were not affected by PP supplementation. The proportions of C18:2n-6 and C18:3n-3 in milk increased linearly as the amount of PP was increased in the diet. Milk urea N, blood urea N, and urinary N excretion decreased linearly with the increase in dietary PP content. Total phenols and antioxidant capacity in milk and plasma were not affected by the inclusion of PP. The activity of ALT increased in a linear manner with the inclusion of PP. In conclusion, replacing up to 10% of BMR with PP improved milk fatty acid composition and alleviated metabolic and environmental N load. However, the elevated serum ALT activity indicates an onset of liver stress even at 5% PP, requiring the development of adaptation protocols for safe inclusion of PP in ruminant diets.

Exposure to volatile organic compounds is a risk factor for diabetes: A cross-sectional study

Currently, more studies showed that environmental chemicals were associated with the development of diabetes. However, the effect of volatile organic compounds (VOCs) on diabetes remained uncertain and needed to be studied. This cross-sectional study examined whether exposure to low levels of VOCs was associated with diabetes, insulin resistance (TyG index) and glucose-related indicators (FPG,HbA1c, insulin) in the general population by using the NHANES dataset (2013-2014 and 2015-2016). We analyzed the association between urinary VOC metabolism (mVOCs) and these indicators in 1409 adults by multiple linear regression models or logistic regression models, further Bayesian kernel machine regression (BKMR) models were performed for mixture exposure analysis. The results showed positive associations between multiple mVOCs and diabetes, TyG index, FPG, HbA1c and insulin, respectively. Among them, HPMMA concentration in urine was significantly positively correlated with diabetes and related indicators (TyG index, FPG and HbA1c), and the concentration of CEMA was significantly positively correlated with insulin. The positive association of mVOCs with diabetes and its related indicators was more significant in the female group and in the 40-59 years group. Thus, our study suggested that exposure to VOCs affected insulin resistance and glucose homeostasis, further affecting diabetes levels, which had important public health implications.

The association between nasal mucosa bacteria and serum metals in children with nasal diseases

Allergic rhinitis (AR) and adenoid hypertrophy (AH) are common nasal diseases in children. Studies have shown that heavy metals are environmental risk factors for nasal diseases, and the pathogenic mechanisms may be related to dysregulation of nasal mucosal microbiota. However, it is unclear how heavy metal exposure relates to the nasal mucosal microbiota in nasal diseases. Therefore, we explored serum metal exposure levels and nasal mucosal microbiota composition in children with different nasal disease, and further studied the potential correlation between metal exposure and disease-related taxa. There were 64 children recruited for this study. The 23 metals concentrations in serum were measured by inductively coupled plasma mass spectrometry, and nasal mucosal bacteria was identified by 16S rRNA sequencing. Nasal diseases (AR and AH) in children were associated with alterations in the abundance and diversity of the nasal mucosal microbiota. The nasal microbiota of children with AR showed lower diversity, while the microbiota of children with AH showed higher diversity. Linear discriminant analysis Effect Size showed 108 differentially abundant taxa between AR and control groups, 35 differentially abundant taxa among large adenoid, moderate adenoid and small adenoid groups. The serum zinc concentration was negatively correlated with Pielou's eveness index and Simpson's Index in children classified by adenoid size. The spearman correlation analysis showed that multiple disease-related taxa were closely associated with metal concentrations in serum. Our findings may support a link between metal exposure and the diversity and composition of nasal bacteria in children with nasal disease, which present new evidence for the effects of metals on children health.

Glutamine supplementation reverses manganese neurotoxicity by eliciting the mitochondrial unfolded protein response

Excessive exposure to manganese (Mn) can cause neurological abnormalities, but the mechanism of Mn neurotoxicity remains unclear. Previous studies have shown that abnormal mitochondrial metabolism is a crucial mechanism underlying Mn neurotoxicity. Therefore, improving neurometabolic in neuronal mitochondria may be a potential therapy for Mn neurotoxicity. Here, single-cell sequencing revealed that Mn affected mitochondrial neurometabolic pathways and unfolded protein response in zebrafish dopaminergic neurons. Metabolomic analysis indicated that Mn inhibited the glutathione metabolic pathway in human neuroblastoma (SH-SY5Y) cells. Mechanistically, Mn exposure inhibited glutathione (GSH) and mitochondrial unfolded protein response (UPR^mt). Furthermore, supplementation with glutamine (Gln) can effectively increase the concentration of GSH and triggered UPR^mt which can alleviate mitochondrial dysfunction and counteract the neurotoxicity of Mn. Our findings highlight that UPR^mt is involved in Mn-induced neurotoxicity and glutathione metabolic pathway affects UPR^mt to reverse Mn neurotoxicity. In addition, Gln supplementation may have potential therapeutic benefits for Mn-related neurological disorders.

Associations between multiple heavy metals exposure and neural damage biomarkers in welders: A cross-sectional study

BACKGROUND

Both occupational and environmental exposure to heavy metals are associated with various neurodegenerative diseases. However, limited evidence is available on the potential effects of exposure to metallic mixtures and neural damage.

OBJECTIVES

This study aimed to evaluate the association between metal mixtures in urine and neural damage biomarkers in welders.

METHODS

In this cross-sectional study, a total of 186 workers were recruited from steel mills. Twenty-three metals in urine were measured by inductively coupled plasma mass spectrometry. Serum neural damage biomarkers, including neurofilament light chain (NfL), sphingosine-1-phosphate (S1P), prolactin (PRL), and dopamine (DA) were detected using enzyme-linked immunosorbent assay kits. Multivariable linear regression, Bayesian kernel machine regression (BKMR), and Quantile g-computation (QG-C) were employed to estimate the association between metals exposure and neural damage biomarkers.

RESULTS

Inverted u-shaped associations of nickel with NfL, S1P, and DA were observed in the BKMR model. A non-linear relationship was also found between Fe and PRL. Urinary cobalt was positively associated with serum PRL and had the strongest positive weights in the QG-C model. Urinary lead was associated with higher serum S1P levels. We also found the interaction among nickel, zinc, arsenic, strontium, iron, and lead with the neural damage biomarkers.

CONCLUSION

This study provides new evidence of a direct association between metal mixture exposure and the serum biomarkers of neural damage. Several metals Ni, Co, Pb, Sr, As and Fe, may have adverse effects on the nervous system, while Zn may have neuroprotective effects.

Glutaminase 1 isoform up-regulation associated with lipid metabolism disorder induced by methyl tertiary-butyl ether in male rats

Methyl tertiary-butyl ether (MTBE) is a new unleaded gasoline additive, which is considered to be associated with abnormal lipid metabolism in many studies, but the metabolic characteristics and mechanism are still unclear. To observe the characteristics of lipid metabolism induced by MTBE and possible pathways, 21 male Wistar rats got intragastric administration for 24 weeks. The serum lipid metabolism indexes and metabolites were analyzed separately by a biochemical analyzer and untargeted metabolomics. And found that serum high-density lipoprotein cholesterol (HDL-C) levels in the exposure group were significantly reduced, and serum very low-density lipoprotein (VLDL) levels were significantly increased. In untargeted metabolomics, 190 differential metabolites were obtained. Among them, 23 metabolites were found to show the same trend in MTBE exposure groups, which might play a key role in systemic energy metabolism. Further metabolic pathways analysis showed that D-Glutamine, D-glutamate metabolism, and the other three pathways were affected by MTBE significantly. Therefore, we evaluated serum glutamine and glutamate levels and found that MTBE exposure significantly reduced glutamine levels and increased glutamate levels in rat serum and L-02 cells. Further, the key regulatory gene of glutamine metabolism, glutaminase 1 isoform (GLS1), was significantly up-regulated in rat liver and L-02 cells exposed to MTBE. While the effect of glutamine and glutamate metabolism induced by MTBE could be weakened by BPTES, an antagonist of GLS1. In conclusion, our results indicated that MTBE exposure could change the level of glutamine metabolism by promoting GLS1 expression and ultimately lead to abnormal lipid metabolism.

Multi-omics analysis reveals Mn exposure affects ferroptosis pathway in zebrafish brain

Manganese (Mn) accumulates in the central nervous system and can cause neurotoxicity, but the mechanisms of Mn-induced neurotoxicity remain unclear. We performed single-cell RNA sequencing (scRNA-seq) of zebrafish brain after Mn exposure and identified 10 cell types by marker genes: cholinergic neurons, dopaminergic (DA) neurons, glutaminergic neurons, GABAergic neurons, neuronal precursors, other neurons, microglia, oligodendrocyte, radial glia, and undefined cells. Each cell type has its distinct transcriptome profile. Pseudotime analysis revealed that DA neurons had a critical role in Mn-induced neurological damage. Combined with metabolomic data, chronic Mn exposure significantly impaired amino acid and lipid metabolic processes in the brain. Furthermore, we found that Mn exposure disrupted the ferroptosis signaling pathway in the DA neurons in zebrafish. Overall, our study employed joint analysis of multi-omics and revealed ferroptosis signaling pathway is a novel potential mechanism of Mn neurotoxicity.

Associations of multiple metals with lung function in welders by four statistical models

BACKGROUND

Exposure to heavy metals has been related to decreased lung function in workers. However, due to limitations in statistical methods for mixtures, previous studies mainly focused on single or several toxic metals, with few studies involving metal exposome and lung function.

OBJECTIVES

The study aimed to evaluate the effects of co-exposure to the metal mixtures on multiple parameters of pulmonary function tests and to identify the elements that play an essential role in elastic-net regression (ENET), multivariate linear regression, bayesian kernel machine regression (BKMR), and quantile g-computation (QG-C) models.

METHODS

We have recruited 186 welders from Anhui (China) in 2019. And their end-of-shift urine and lung function measure data were collected with informed consent. The urinary concentrations of 23 metals were measured by inductively coupled urinary mass spectrometry. The lung function measures including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) were also detected as outcome indicators. Four statistical methods, ENET, multivariate linear regression, BKMR, and QG-C models were used to evaluate the associations of element mixtures on lung function comprehensively.

RESULTS

Lead and cadmium were negatively associated with FVC and FEV1, nickel and chromium were inversely associated with PEF, and strontium showed significant positive effects in linear regression models, which were consistent with the results in BKMR and QG-C models. Both BKMR and QG-C models showed a significantly negative overall effect of metal mixtures on lung function parameters (FVC, FEV1, and PEF). Meanwhile, BKMR showed the non-linear relationships of cadmium with FVC.

CONCLUSION

Multi-pollutant mixtures of metals were negatively associated with lung function. Lead, cadmium, nickel, and strontium might be crucial elements. Our findings highlight a need to prioritize workers' environmental health, and guide future research into the toxic mechanisms of metal-mediated lung function injury.

The burden of pneumoconiosis in China: an analysis from the Global Burden of Disease Study 2019

Background

Pneumoconiosis refers to a class of serious diseases threatening the health of workers exposed to coal or silicosis dust. However, the burden of pneumoconiosis is unavailable in China.

Methods

Incident cases, deaths, and disability-adjusted life years (DALYs) from pneumoconiosis and its subtypes in China were estimated from the Global Burden of Disease Study 2019 using a Bayesian meta-regression method. The trend of the burden from pneumoconiosis was analyzed using percentage change and annualized rate of change (ARC) during the period 1990–2019. The relationship between subnational socio-demographic index (SDI) and the ARC of age-standardised death rate was measured using Spearman’s Rank-Order Correlation.

Results

In 2019, there were 136.8 (95% uncertainty interval [UI] 113.7–162.5) thousand new cases, 10.2 (8.1–13.6) thousand deaths, and 608.7 (473.6–779.4) thousand DALYs from pneumoconiosis in China. Of the global burdens from pneumoconiosis, more than 60% were in China. Both the total number of new cases and DALYs from pneumoconiosis was keeping increasing from 1990 to 2019. In contrast, the age-standardised incidence, death, and DALY rates from pneumoconiosis and its subtypes, except for the age-standardised incidence rate of silicosis, and age-standardised death rate of asbestosis, experienced a significant decline during the same period. The subnational age-standardised death rates were higher in western China than in eastern China. Meanwhile, the subnational ARC of age-standardised death rates due to pneumoconiosis and its subtypes were significantly negatively correlated with SDI in 2019.

Conclusion

China suffers the largest health loss from pneumoconiosis in the world. Reducing the burden of pneumoconiosis is still an urgent task in China.

Reduced mitochondrial DNA copy number in occupational workers from brominated flame retardants manufacturing plants

Decabrominated diphenyl ether (BDE-209) and its substitute decabromodiphenyl ethane (DBDPE) are two flame retardants that have similar structure and are widely used in various industrial products. The accumulation and potential toxicity of them to human health have already aroused attention, and some research showed that they may affect mitochondrial function. Therefore, this study focused on the population with high exposure to brominated flame retardants (BFRs) and the related changes in mtDNA copy number (mtDNAcn) in whole blood. 334 blood samples were collected from three groups of people in Shandong Province, including 42 BDE-209 occupational exposure workers from the BDE-209 manufacturing plant, 131 DBDPE occupational exposure workers from the DBDPE manufacturing plant, and 161 non-BFRs occupational exposure residents from the BFRs contaminated area. We measured the levels of BDE-209, DBDPE in serum sample, and the mtDNAcn in whole blood sample and analyzed these data by multiple linear regression. The average concentrations of BDE-209, DBDPE and ∑(BDE-209 + DBDPE) in BDE-209 occupational workers were 3510, 639 and 4600 ng/g lw, respectively; the average concentrations of BDE-209, DBDPE and ∑(BDE-209 + DBDPE) in DBDPE occupational workers were 229, 4040 and 4470 ng/g lw, respectively; the average concentrations of BDE-209, DBDPE and ∑(BDE-209 + DBDPE) in non-BFRs occupational exposure residents were 66.3, 45.7 and 137 ng/g lw, respectively. The relative mtDNAcn was 0.823 in BDE-209 occupational workers, 0.845 in DBDPE occupational workers and 0.989 in non-BFRs occupational exposure residents. A 10-fold increase in BDE-209, DBDPE concentrations was separately associated with a 0.068 and 0.063 decrease in mtDNAcn. Therefore, our study implied that BFRs may affect mitochondrial function. As increasing BFRs exposure has emerged in recent years, the relationship between BFRs exposure and mitochondrial function needs further study.

Exposure to the real ambient air pollutants alters the composition of nasal mucosa bacteria in the rat model

Studies have indicated that ambient pollutant exposure correlates with nasal disease, in which nasal mucosa microbiota play a crucial role. However, the association between exposure to real-ambient air pollutants and the composition of nasal mucosa microbiota has not been well studied. This study aimed to explore the composition of nasal mucosa microbiota after exposure to real-ambient air pollutants with a special system. We monitored PM_2.5, O₃, etc. in the system and confirmed PM_2.5 and O₃ were the main pollutants. SD rats were exposed to the system for 16 weeks in summer or 22 weeks in autumn-winter. The concentrations of PM_2.5 were 24.00 μg/m³ in the Summer stage and 22.21 μg/m³ in the autumn-winter stage. The O₃ concentrations were 25.46 and 13.55 μg/m³, respectively. Exposure altered bacterial beta diversity in the summer stage. There were 4 and 3 different bacteria at the king, order, family and genus levels between the two groups at the two stages, respectively. The abundance of opportunistic pathogens changed, Pseudomonas decreased in summer stage, and Bifidobacterium increased in the autumn-winter stage. The influence of the season on the nasal mucosa microbiota was analyzed. The alpha diversity of the autumn-winter stage was higher than that of the summer stage. LEfSe analysis revealed 34 differential bacterial taxa at the king, order, family and genus level in the two control groups and 31 of the two exposure groups, which were not the same as the bacteria between the control groups and exposure groups. We found that PM_2.5 combined with O₃ exposure was associated with the composition of the nasal mucosa microbiota and the abundance of opportunistic pathogens, in which season likely impacted the microbiota.

Associations of low level of fluoride exposure with dental fluorosis among U.S. children and adolescents, NHANES 2015-2016

Drinking water fluoridation was a mid-twentieth century innovation based on the medical hypothesis that consuming low doses of fluoride at the teeth forming years provided protection against dental decays. Numerous studies showed that high level exposure to fluoride could cause dental and skeleton fluorosis. However, there was limited study focusing on the fluorosis effect of low levels of exposure to fluoride. Therefore, our study aimed to examine whether the low level of fluoride exposure (measured in blood plasma and household tap water) was associated with the risk of dental fluorosis based on data of the National Health and Nutrition Examination Survey (NHANES) 2015-2016. We analyzed data in 2098 children and adolescents who had Dean's Index scores, and water and plasma fluoride measures. The Dean's Index score was measured by calibrated dental examiners using the modified Dean's fluorosis classification system. Fluoride was measured in plasma and household tap water. In this study, we found that the rate of fluoride concentration in water above the recommended level of 0.7 mg/L was 25%, but the prevalence of dental fluorosis was 70%. Binary logistic regression adjusted for covariates showed that higher water fluoride concentrations (0.31-0.50, 0.51-0.70, > 0.70 compared 0.00-0.30) were associated with higher odds of dental fluorosis (OR = 1.48, 95% CI: 1.13-1.96, p = 0.005; OR = 1.92, 95% CI: 1.44-2.58, p < 0.001, and OR = 2.30, 95% CI: 1.75-3.07, p < 0.001, respectively). The pattern of regression between plasma fluoride and dental fluorosis was similar. Inclusion, our study showed that even low level of water or plasma fluoride exposure was associated with increased the risk of dental fluorosis. The safety of public health approach of drinking water fluoridation for global dental caries reduction are urgently needed further research.

Amorphous silica nanoparticles accelerated atherosclerotic lesion progression in ApoE-/- mice through endoplasmic reticulum stress-mediated CD36 up-regulation in macrophage

Background

The biosafety concern of silica nanoparticles (SiNPs) is rapidly expanding alongside with its mass production and extensive applications. The cardiovascular effects of SiNPs exposure have been gradually confirmed, however, the interaction between SiNPs exposure and atherosclerosis, and the underlying mechanisms still remain unknown. Thereby, this study aimed to explore the effects of SiNPs on the progression of atherosclerosis, and to investigate related mechanisms.

Results

We firstly investigated the in vivo effects of SiNPs exposure on atherosclerosis via intratracheal instillation of ApoE^−/− mice fed a Western diet. Ultrasound microscopy showed a significant increase of pulse wave velocity (PWV) compared to the control group, and the histopathological investigation reflected a greater plaque burden in the aortic root of SiNPs-exposed ApoE^−/− mice. Compared to the control group, the serum levels of total triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) were elevated after SiNPs exposure. Moreover, intensified macrophage infiltration and endoplasmic reticulum (ER) stress was occurred in plaques after SiNPs exposure, as evidenced by the upregulated CD68 and CHOP expressions. Further in vitro, SiNPs was confirmed to activate ER stress and induce lipid accumulation in mouse macrophage, RAW264.7. Mechanistic analyses showed that 4-PBA (a classic ER stress inhibitor) pretreatment greatly alleviated SiNPs-induced macrophage lipid accumulation, and reversed the elevated CD36 expression induced by SiNPs.

Conclusions

Our results firstly revealed the acceleratory effect of SiNPs on the progression of atherosclerosis in ApoE^−/− mice, which was related to lipid accumulation caused by ER stress-mediated upregulation of CD36 expression in macrophage.

Graphical abstract

Multiple-centre clinical evaluation of an ultrafast single-tube assay for SARS-CoV-2 RNA

OBJECTIVE

To evaluate the performance of an ultrafast single-tube nucleic acid isothermal amplification detection assay for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA using clinical samples from multiple centres.

METHODS

A reverse transcription recombinase-aided amplification (RT-RAA) assay for SARS-CoV-2 was conducted within 15 minutes at 39°C with portable instruments after addition of extracted RNA. The clinical performance of RT-RAA assay was evaluated using 947 clinical samples from five institutions in four regions of China; approved commercial fluorescence quantitative real-time PCR (qRT-PCR) kits were used for parallel detection. The sensitivity and specificity of RT-RAA were compared and analysed.

RESULTS

The RT-RAA test results of 926 samples were consistent with those of qRT-PCR (330 were positive, 596 negative); 21 results were inconsistent. The sensitivity and specificity of RT-RAA was 97.63% (330/338, 95% confidence interval (CI) 95.21 to 98.90) and 97.87% (596/609, 95% CI 96.28 to 98.81) respectively. The positive and negative predictive values were 96.21% (330/343, 95% CI 93.45 to 97.88) and 98.68% (596/604, 95% CI 97.30 to 99.38) respectively. The total coincidence rate was 97.78% (926/947, 95% CI 96.80 to 98.70), and the kappa was 0.952 (p < 0.05).

CONCLUSIONS

With comparable sensitivity and specificity to the commercial qRT-PCR kits, RT-RAA assay for SARS-CoV-2 exhibited the distinctive advantages of simplicity and rapidity in terms of operation and turnaround time.

Thyroid function and decabromodiphenyl ethane (DBDPE) exposure in Chinese adults from a DBDPE manufacturing area

Polybrominated diphenyl ethers (PBDEs), which are persistent organic pollutants, affect thyroid function. Human exposure to decabromodiphenyl ethane (DBDPE), which has a similar structure to PBDEs, has recently increased, and the health effects of DBDPE have not been well studied. The objective of this study was to determine whether human exposure to DBDPE was associated with thyroid hormone levels in adults from a DBDPE manufacturing area. Three hundred-two blood samples were collected from two populations in the largest DBDPE manufacturing area located in North China: 133 DBDPE occupationally exposed workers from a DBDPE manufacturing plant and 169 non-DBDPE occupationally exposed residents from a nearby food processing plant. The levels of DBDPE, and thyroid function parameters [total thyroxine (TT4), free T4 (FT4), total triiodothyronine (TT3), free T3 (FT3), thyroid-stimulating-hormone (TSH), thyroglobulin antibody (TG-Ab), and thyroid peroxidase antibody (TPO-Ab)] were measured in serum samples. Serum concentrations of DBDPE ranged from 3.148 to 54,360 ng g^-1 lipid weight (lw), with a geometric mean of 332.6 ng g^-1 lw. A 10-fold increase in the DBDPE concentration was associated with increase of 4.73 nmol L^-1 [95% confidence interval (CI): 2.75, 6.71] TT4 and 0.046 nmol L^-1 TT3 [95% CI: 0.012, 0.081], corresponding to increases of approximately of 4.73% (95% CI: 2.75%-6.71%) and 2.38% (95% CI: 0.62%-4.20%), respectively. DBDPE in serum was also significantly and positively associated with the concentrations of TG-Ab and TPO-Ab. Our study found that exposure to DBDPE was associated with changes in thyroid activity in adults exposed to a high concentration of DBDPE, mainly increases of TT4, TT3, TPO-Ab, and TG-Ab. The association between DBDPE exposure and thyroid homeostasis requires further investigation because increasing DBDPE exposure has emerged in recent years.

Investigation of the impact of PM2.5 on the ciliary motion of human nasal epithelial cells

Nasal epithelium provides a physical barrier to potentially harmful stimuli. Cilia, which is on the apical side of the human nasal epithelial cells (HNEpCs), plays a critical role in removing inhaled harmful matter. Ciliary beat frequency (CBF) and ciliary beat pattern (CBP) are the two important indicators for ciliary beat function. However, impacts of the fine particulate matter (PM_2.5) on CBF and CBP are still unknown. We aimed to evaluate the impact of PM_2.5 on the ciliary beat function of the HNEpCs and its potential mechanisms. After exposed to PM_2.5 for 12 h, cilia of HNEpCs were in disordered arrangement. The ciliary coverage rate was decreased after PM_2.5 exposure of a series of concentration, while the proportion of basal cells was continuously increased and could be observed on the apical side of the HNEpCs which is hardly be observed without PM_2.5 exposure. PM_2.5 increased the CBF after 12 h exposure, while 24 h exposure increased the CBF at the relative lower dosage groups and then made a decrease at relative higher dosage groups. CBF were classified into two different types, which had different changes following PM_2.5 exposure. CBP showed significant changes characterized as the increased dyskinesia index. Total levels of cellular ATP and the mitochondrial membrane potential were decreased following 12 h exposure of PM_2.5, while no change was found in O₂ consumption. In conclusion, PM_2.5 impact the ciliary beat function of HNEpCs, and the mitochondrial dysfunction might play an important role in it.

Overexpression of miR-138-5p suppresses MnCl2 -induced autophagy by targeting SIRT1 in SH-SY5Y cells

The mechanism of manganism caused by manganese (Mn), an important environmental risk factor for Parkinson's disease, is still unclear. Recent evidence suggested that autophagy participated in neurodegenerative diseases, in which microRNA played a crucial role. However, roles of microRNA in the aberrant autophagy that occurs in neurodegenerative diseases remains controversial. In nervous system, miRNA-138-5p is highly expressed and plays a key role in regulating memory and axon regeneration. Importantly, we also found that miR-138-5p expression decreased significantly after SH-SY5Y cells exposed to manganese chloride (MnCl₂ ) in previous study. To explore the role of miR-138-5p in Mn-induced autophagy, autophagy associated indicators were detected. And we found that MnCl₂ could induce autophagic dysregulation and inhibit expression of miR-138-5p. While the levels of LC3-II/LC3-I, Beclin1, and p62, the number of autophagosome formation significantly decreased after miR-138-5p over-expression, which demonstrated that miR-138-5p could clearly retard Mn-induced autophagy. In additional, we found there were classical and evolutionarily conserved miR-138-5p binding sites in 3'-UTR region of SIRT1, which was inhibited when overexpression of miR-138-5p. Therefore, it was speculated that elevated expression of SIRT1 may be resulted from inhibition of miR-138-5p after cells exposed to MnCl₂ . Finally, we found that SIRT1 inhibitor EX-527 suppressed Mn-induced autophagy as well as miR-138-5p, while the suppression was reversed by SIRT1-specific activator SRT1720. These results indicated that overexpression of miR-138-5p suppressed Mn-induced autophagy by targeting SIRT1.

Disruption of thyroid hormone levels by decabrominated diphenyl ethers (BDE-209) in occupational workers from a deca-BDE manufacturing plant

While there is some evidence that exposure to decabrominated diphenyl ethers (BDE-209) affects thyroid function, the results obtained to date have been inconsistent. No studies have been performed on workers in deca-BDE manufacturing who had a high level of exposure to BDE-209 and relatively little exposure to other contaminants. In the present study, the relationship between BDE-209 exposure and thyroid hormone in occupational workers from a deca-BDE manufacturing plant was investigated. The serum and urine levels of polybrominated diphenyl ethers (PBDEs) and serum thyroid hormones were measured in 72 workers recruited from the deca-BDE manufacturing plant. The associations between their thyroid hormone levels and their exposure to BDE-209 were examined using multiple linear regression models. Serum concentrations of BDE-209 ranged from 67.4 to 109,000 ng/g lipid weight (lw), with a median of 3420 ng/g lw, contributing to 93.1% of the total PBDEs. The concentration of BDE-209 in urine was highly correlated with that in the serum (r² = 0.440, p < 0.001), indicating that urine may be a good non-invasive biomonitoring medium of BDE-209 body burden in occupational workers. BDE-209 in the serum was significantly and positively correlated with total thyroxine (tT4, r = 0.270, p = 0.029) and marginally and positively correlated with total triiodothyronine (tT3, r = 0.232, p = 0.061) in all occupational workers after adjusting for gender, age, BMI, and occupational exposure duration. A 10-fold increase in the serum BDE-209 concentration was associated with an increase in tT4 (8.63 nmol/L) [95% confidence interval (CI): 0.930-16.3] and tT3 (0.106 nmol/L) [95% confidence interval (CI): -0.005-0.219], corresponding to the increase of 7.8% in tT4 level and 5.4% in tT3 level. Associations between urine BDE-209 levels and thyroid hormones were similar to the results for the serum levels. These findings offer new evidence for proving the thyroid disrupting effects of BDE-209, impacting the direction of hyperthyroidism.

Silica nanoparticles induced endothelial apoptosis via endoplasmic reticulum stress-mitochondrial apoptotic signaling pathway

Along with their extensively application, human exposure to amorphous silica nanoparticles (SiNPs) has highly increased. Accumulative toxicological researches have provided the scientific correlation between SiNPs exposure and cardiovascular diseases. Endothelial apoptosis is vital in the initiation and progression of atherosclerosis. However, molecular details between SiNPs and endothelial apoptosis remain unidentified. Here, we investigated the uptake and toxic mechanism of SiNPs using HUVECs (Human umbilical vein endothelial cells). Consequently, at 24-h exposure, SiNPs were located freely or within membrane-bound agglomerates in the cytosol, especially in mitochondrial and endoplasmic reticulum (ER) regions with swelled mitochondria, cristae rupture or aggregated ER. Further, we demonstrated that SiNPs induced endothelial apoptosis as evidenced by the Annexin V/PI staining and flow cytometry determination. In line with the ultrastructure alterations, SiNPs triggered mitochondrial ROS generation, ΔΨm collapse, cytosolic Ca²⁺ overload, as well as ER stress confirmed by enhanced ER staining, up-regulated GRP78/BiP and XBP1 splicing. More notably, in line with the induction of apoptosis, SiNPs-induced ER stress-associated activation of CHOP, caspase-12, and IRE1α/JNK pathways, which may regulate the BCL2 family member as evidenced by a increased proapoptotic BAX while a decline of anti-apoptotic Bcl-2, ultimately facilitate the mitochondria-mediated apoptotic caspase cascade as confirmed by the upregulated expressions of cytochrome c, Caspase-9 and -3. Altogether, our results indicated the activation of ER stress-mitochondria cascade-mediated apoptotic pathways may be a key mechanism among the SiNPs-induced endothelial apoptosis.

FOXO3 promoted mitophagy via nuclear retention induced by manganese chloride in SH-SY5Y cells

OBJECTIVES

To evaluate the role of FOXO3 during the process of mitophagy induced by manganese chloride (MnCl₂), mitochondrial dysfunction and mitophagy were detected before and after FOXO3 was knocked down in SH-SY5Y cells.

METHOD

Transmission electron microscopy (TEM), flow cytometry, confocal microscopy and a western blot were used to detect mitochondrial ultrastructure and autophagy, Ca²⁺ levels, mitochondrial reactive oxygen species (ROS) and the mitochondrial membrane potential (MMP), autophagosomes and mitophagy marker proteins (p62, LC3-II/LC3-I, Beclin-1, PINK1 and P-parkin), respectively.

RESULTS

After SH-SY5Y cells were exposed to MnCl₂, the levels of cytoplasmic Ca²⁺ and mitochondrial ROS increased but the mitochondrial MMP decreased significantly compared to the control in a dose- and time-dependent manner (p < 0.05), which indicated that MnCl₂ can lead to mitochondrial dysfunction. Under TEM, mitophagy and autolysosomes were observed. The WB results also showed that mitophagy marker proteins including LC3-II/LC3-I, Beclin-1, PINK1 and P-parkin except for p62 increased in a dose- and time-dependent manner, accompanied by FOXO3 nuclear retention, which indicated that MnCl₂ can lead to mitophagy and FOXO3 nuclear translocation may be involved in this process. After FOXO3 was knocked down, the inverse results of mitophagy and the levels of mitochondrial ROS decreasing were observed, which showed that FOXO3 silencing could inhibit mitophagy and mitochondrial dysfunction induced by MnCl₂.

CONCLUSIONS

Our results indicated that Mn could induce mitophagy by enhancing FOXO3 nuclear retention, which might promote mitophagy induced by MnCl₂.

SIRT1 exhibits antioxidative effects in HT22 cells induced by tert-butyl alcohol

Tertiary butyl alcohol (TBA) is a principal metabolite of methyl tertiary-butyl ether (MTBE), a common pollutant worldwide in the ground or underground water, which is found to produce nervous system damage. Nevertheless, few data regarding the effects of TBA has been reported. Studies indicated that oxidative stress plays a pivotal role in MTBE neurotoxic mechanism. Sirtuin 1 (SIRT1) has been reported to exert a neuroprotective effect on various neurologic diseases via resistance to oxidative stress by deacetylating its substrates. In this study, we examined levels of oxidative stress after exposure to TBA for 6 h in HT22 cells and HT22 cells with SIRT1 silencing (transfected with SIRT1 siRNA) or high expression (preconditioned with agonists SRT1720). We found that TBA activated oxidative stress by increasing generation of intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and Oxidized glutathione (GSSG), and decreasing contents of superoxide dismutase (SOD) and glutathione reductase (GSH). In additional, levels of TBA-induced oxidative stress were aggravated when SIRT1 silenced but alleviated when SIRT1 enhanced. Our study indicated that SIRT1 mitigated oxidative stress induced by TBA.

MicroRNA-29b inhibits supernatants from silica-treated macrophages from inducing extracellular matrix synthesis in lung fibroblasts

Silicosis is pathologically characterized by diffused pulmonary fibrosis and abundant deposition of extracellular matrix (ECM) components. The ECM is mainly secreted by myofibroblasts which are the activated state of fibroblasts. MicroRNA-29b (miR-29b) is one of the well-known microRNAs involved in fibrosis, but its roles in silicosis have not been specified. In this study, we hypothesized that miR-29b might play a protective role in the progression of silicosis. MTT assay, qRT-PCR, immunofluorescence and western blotting were applied. The results demonstrated that the supernatants from silica-treated macrophages not only caused the proliferation of fibroblasts (NIH-3T3 and MRC-5) but were also involved in the down-regulation of miR-29b. Meanwhile they could induce fibroblast activation, increasing the expression of ECM components such as collagen1 and collagen3, in a silica dose-dependent manner. Furthermore, overexpression of miR-29b by transfecting mimics markedly reduced the expression of ECM components and inhibited ECM synthesis. These findings indicate that miR-29b inhibits the supernatants from silica-treated macrophages from inducing extracellular matrix synthesis, thus miR-29b might have a strong anti-fibrotic capacity in silicosis and serve as a potential therapeutic agent for the treatment.

SIRT1 attenuated oxidative stress induced by methyl tert-butyl ether in HT22 cells

Methyl tertiary-butyl ether (MTBE), an unleaded gasoline additive, can lead to oxidative stress, thus injuring the nervous system after long-term exposure. SIRT1, a NAD+-dependent histone deacetylase, can play a neuroprotective role in brain injury. However, the mechanism is unclear. This present study intended to define the role of SIRT1 during the process of MTBE-induced oxidative stress in mouse hippocampal neurons (HT22 cells). Our data showed that MTBE could directly trigger oxidative stress in HT22 cells by decreasing the activity of superoxide dismutase (SOD) and GSH/T-GSH level while increasing ROS, lipid peroxidation product malondialdehyde (MDA) and GSSG level. Similarly, the expression of SIRT1, an antioxidant, decreased in a dose-dependent manner. To further explore whether SIRT1 plays a key role during the process of oxidative stress, HT22 cells were transfected with siRNA-SIRT1 and preconditioned with the agonist of SIRT1 (SRT1720) for 2 h. The levels of oxidative stress (ROS, SOD, MDA, GSH/GSSG) were detected again after siRNA-SIRT1 HT22 cells and SRT1720 HT22 cells were exposed to MTBE for 6 h. In contrast to the non-pretreated group, levels of oxidative stress were tonic in siRNA-SIRT1 HT22 cells and attenuated in SRT1720 HT22 cells. Our results indicate that MTBE could directly cause oxidative stress in HT-22 cells, and SIRT1 might be an important antioxidant during MTBE-induced oxidative stress.

The protective effects of bone morphogenetic protein-7 against epithelial injury and matrix metalloproteases upregulation induced by silica in vitro

OBJECTIVE

We investigate the effects of bone morphogenetic protein-7 (BMP-7) on models with silica-induced and macrophage-mediated fibrosis and its possible mechanisms in vitro.

METHODS

Rat alveolar II epithelial (RLE-6TN) cells were incubated with the supernatant of mouse macrophage-like cells (RAW264.7) and treated with 0, 25, 50, and 100 μg/mL silica. Using Western blotting, the epithelial markers (surfactant proteins-C and E-cadherin) and the mesenchymal markers (fibronectin (FN) and viminten (Vim)) were detected. After neutralizing the BMP-7, the progress of fibrosis was assessed by the content of hydroxyproline (Hyp) and collagen I, III protein levels as well as the Smad signaling pathway proteins, including phosphorylated Smad1/5(P-Smad1/5) and phosphorylated Smad2/3(P-Smad2/3). Collagen I was also identified by immunofluorescence and pretreated with SB-431542, LDN-193189, or anti-BMP-7-neutralizing antibody. In addition, the levels of matrix metalloproteinase-2 (MMP-2) and MMP-9 were detected using Western blotting.

RESULTS

The model of RLE-6TN cells was established successfully, the expressions of Vim, FN, MMP-2, and MMP-9 were upregulated, while the concentration of silica is increased. Neutralizing BMP-7 stimulated the decrease of P-Smad1/5 and the increase of P-Smad2/3, as well as the collagen I, collagen III, FN, and Hyp via Smad signaling pathway. Furthermore, pretreated with LDN-193189 or anti-BMP-7-neutralizing antibody, the expression of collagen I was increased, yet it was decreased with SB-431542 intervention.

CONCLUSION

The activated BMP/Smad and suppressed transforming growth factor-β/Smad pathways could suppress silica-induced fibrosis via a MMP-dependent mechanism. BMP-7 is expected to be the optimized strategy of delaying the interstitial changes.

Bone morphogenetic protein-7 prevented epithelial-mesenchymal transition in RLE-6TN cells

Bone morphogenetic protein-7 (BMP-7) plays an important role in the epithelial-mesenchymal transition (EMT) process, and has been identified as the most potent factor that can promote mesenchymal-epithelial transition (MET) and reduce organ fibrosis. Here we examined the important role of BMP-7 in silica-induced EMT and investigated the relationship between BMP-7 and the balance of EMT/MET. We found that silica induced EMT and decreased the expression of BMP-7 in vivo and in vitro, while silica activated the p38 MAPK/transcription factor signaling pathway in RLE-6TN cells. Lentivirus mediated transfection was used to stably upregulate the expression of BMP-7. Exogenous BMP-7 brought on MET exceeded silica-induced EMT and restrained the p38 MAPK/transcription factor signaling pathway in RLE-6TN cells. Our results revealed that BMP-7 promoted MET above EMT induced by silica associated with inhibition of the p38 MAPK/transcription factor signaling pathway, and BMP-7 was a potential target for treatment of silicosis fibrosis.

Sodium tanshinone IIA sulfonate suppresses pulmonary fibroblast proliferation and activation induced by silica: role of the Nrf2/Trx pathway

Alveolar macrophages are believed to induce oxidative stress via reactive oxygen species (ROS) when silica particles are inhaled. This process can contribute to the pathogenesis of silicosis, but the mechanism is unclear. A traditional Chinese herbal derivative, sodium tanshinone IIA sulfonate (STS), displays significant antioxidant effects. Here, we determine whether STS can attenuate the oxidative stress induced by silica. Traditionally, studies on the toxic effects of silica have focused on monocultures of macrophages or fibroblasts. A coculture model of macrophages (Raw 264.7) and pulmonary fibroblasts (MRC-5) was used in this study to mimic a more in vivo-like environment. We investigated the protective effects of STS on the abnormal proliferation of MRC-5 fibroblasts in an in vitro model. The results showed that fibroblast viability increased with the accumulation of intracellular ROS induced by cocultured Raw 264.7 cells after silica exposure. Treatment with STS markedly ameliorated the silica-induced cell proliferation and oxidative stress. Western blotting and immunofluorescence analysis of the Nrf2 and thioredoxin (Trx) system were conducted, and the results confirmed that treatment with STS enhanced nuclear Nrf2 accumulation and mediated antioxidant Trx system expression. These findings suggest that silica exposure might induce some level of oxidative stress in fibroblasts and that STS might augment antioxidant activities via up-regulation of the Nrf2 and Trx system pathways in MRC-5 cells in vitro.

BMP-7 attenuated silica-induced pulmonary fibrosis through modulation of the balance between TGF-β/Smad and BMP-7/Smad signaling pathway

OBJECTIVE

To investigate the anti-fibrotic effects and possible mechanisms of bone morphogenetic protein-7 (BMP-7) on silica induced fibrosis in RLE-6TN cells, and compare the preventive treatment of experimental silicosis with BMP-7 with therapeutic treatment of silicosis in vitro models.

METHODS

RLE-6TN cells were incubated with the supernatant of RAW264.7, treated by 50 μg/mL silica in either presence or absence of BMP-7 in different phases. Morphological changes and the cellular wound-healing assays were used to evaluate the process of EMT. By using Western Blotting, the epithelial marker E-cadherin (E-cad), and the mesenchymal markers Vimentin (Vim), Snail, and fibronectin (FN) were detected as well as the Smad signaling pathway proteins, including phosphorylated Smad1/5(P-Smad1/5), phosphorylated Smad2/3(P-Smad2/3), and non-phosphorylated Smad1, Smad8, and Smad2. The progress of fibrosis was assessed by the content of hydroxyproline (Hyp) and collagen I and III protein levels. In addition, MTT assay was used to explore the toxic effects of silica as well as BMP-7.

RESULTS

The EMT model of RLE-6TN cells was established successfully, the cells had a fibroblast-like morphology with increasing migration activity. The expressions of Vim, Snail, FN, collagen I and collagen III were up-regulated with the increase of silica concentration. BMP-7 could attenuate the decrease of P-Smad1/5 and the increase of P-Smad2/3, collagen I, collagen III, and FN via Smad signaling pathway. BMP-7 inhibited the mesenchymal-like responses in RLE-6TN cells, including cell migration, expression of fibrosis markers, and secretion of Hyp. Furthermore, the anti-fibrotic effects in the prevention group were more effective than treatment group.

CONCLUSION

The restoration of BMP signaling with BMP-7 is associated with inhibiting silica-induced fibrosis through the mechanisms of activated BMP-7/Smad and suppressed TGF-β/Smad pathways. Preventive treatment of pulmonary fibrosis progression with BMP-7 may expect to be the optimized strategy than therapeutic therapy of fibrosis.

Prognostic significance of serum sMICA levels in non-small cell lung cancer

OBJECTIVE

The soluble form of major histocompatibility complex class I-related chain A (MICA) is released from the surface of tumor cells of epithelial origin. Serum levels of soluble MHC class I-related chain A (sMICA) is related with the prognosis of various types of cancer. However, there are studies on the prognostic value of sMICA in non-small cell carcinoma (NSCLC). In this study, we retrospectively investigated the relationship between sMICA levels and clinical features of NSCLC, and we assessed the prognostic value of sMICA in NSCLC.

PATIENTS AND METHODS

sMICA levels were detected in 207 NSCLC patients and 207 normal control individuals with using enzyme-linked immunosorbent assay (ELISA), and its associations with clinicopathological parameters were evaluated. Survival curves were compared using the Kaplan-Meier method and log-rank tests. Univariate Cox regression was used on each clinical covariate to examine its influence on patient survival. Multivariate models were based on step-wise addition.

RESULTS

Serum sMICA levels were significantly higher in NSCLC patients than in healthy controls (mean ± SD [pg/ml], 143.52 ± 27.6 vs. 32.4 ± 7.53 p < 0.01) and were significantly correlated with TNM stage, poorer differentiation, lymph node metastases and distant metastases. Survival analysis showed that a low sMICA level had longer survival time than those with high serum sMICA. Multivariate analyses indicated that high sMICA proved to be an independent predictor of survival time.

CONCLUSIONS

Serum sMICA level in NSCLC patients is associated with metastasis. It is an indicator of a poorer survival probability. Serum sMICA levels may be an independent prognostic factor for NSCLC.

Effect of bone morphogenic protein-7 on the expression of epithelial-mesenchymal transition markers in silicosis model

This study presented the effect of bone morphogenic protein-7 (BMP-7) inhibiting epithelial-mesenchymal transition (EMT) in silicosis model. In vivo, Wistar rats were exposed to silica by intratracheal instillation. Seven days later rats were treated with BMP-7. Rats were sacrificed at 15 and 30days after exposure of silica. The results demonstrated vimentin expression was down-regulated; and E-cadherin was up-regulated after intervention with BMP-7. The TGF-β expression and phosphorylation-p38 were lower in BMP-7 treated group than in silica group. In vitro, p38 MAPK/Snail signaling pathway was involved in the occurrence of EMT in A549 cells treated by silica. EMT was inhibited by BMP-7. The data showed BMP-7 inhibited EMT induced by silica associated with inhibition of p38 MAPK/Snail pathway.

Bone morphogenetic protein 7 attenuates epithelial-mesenchymal transition induced by silica

The epithelial-mesenchymal transition (EMT) is a critical process in the pulmonary fibrosis. It has been reported that bone morphogenetic protein 7 (BMP-7) was able to reverse EMT in proximal tubular cells. Therefore, we test the hypothesis that EMT contributes to silica-induced pulmonary fibrosis and BMP-7 inhibits EMT in silica-induced pulmonary fibrosis. Progressive silica-induced pulmonary fibrosis in the rat was used as a model of silicosis. Epithelial and mesenchymal markers were measured from rat fibrotic lungs. Then the effects of BMP-7 on the EMT were further confirmed in A549 cells. There are increases of vimentin as a mesenchymal marker and decreases of E-cadherin as an epithelial marker in the silica-exposed rat lungs, which is in agreement with the A549 cells data. However, BMP-7 treatment significantly reduced expression of vimentin in the rat pulmonary fibrosis model and in A549 cells. In conclusion, EMT contributes to silica-induced pulmonary fibrosis. Meanwhile, the treatment of BMP-7 can inhibit silica-induced EMT in vitro and in vivo.

Silica nanoparticles induce oxidative stress, inflammation, and endothelial dysfunction in vitro via activation of the MAPK/Nrf2 pathway and nuclear factor-κB signaling

Despite the widespread application of silica nanoparticles (SiNPs) in industrial, commercial, and biomedical fields, their response to human cells has not been fully elucidated. Overall, little is known about the toxicological effects of SiNPs on the cardiovascular system. In this study, SiNPs with a 58 nm diameter were used to study their interaction with human umbilical vein endothelial cells (HUVECs). Dose- and time-dependent decrease in cell viability and damage on cell plasma-membrane integrity showed the cytotoxic potential of the SiNPs. SiNPs were found to induce oxidative stress, as evidenced by the significant elevation of reactive oxygen species generation and malondialdehyde production and downregulated activity in glutathione peroxidase. SiNPs also stimulated release of cytoprotective nitric oxide (NO) and upregulated inducible nitric oxide synthase (NOS) messenger ribonucleic acid, while downregulating endothelial NOS and ET-1 messenger ribonucleic acid, suggesting that SiNPs disturbed the NO/NOS system. SiNP-induced oxidative stress and NO/NOS imbalance resulted in endothelial dysfunction. SiNPs induced inflammation characterized by the upregulation of key inflammatory mediators, including IL-1β, IL-6, IL-8, TNFα, ICAM-1, VCAM-1, and MCP-1. In addition, SiNPs triggered the activation of the Nrf2-mediated antioxidant system, as evidenced by the induction of nuclear factor-κB and MAPK pathway activation. Our findings demonstrated that SiNPs could induce oxidative stress, inflammation, and NO/NOS system imbalance, and eventually lead to endothelial dysfunction via activation of the MAPK/Nrf2 pathway and nuclear factor-κB signaling. This study indicated a potential deleterious effect of SiNPs on the vascular endothelium, which warrants more careful assessment of SiNPs before their application.

Increased expression of bone morphogenetic protein-7 and its related pathway provides an anti-fibrotic effect on silica induced fibrosis in vitro

BMP-7 exerts an inhibitory effect on silica induced fibrosis in RLE-6TN cells via suppressing TGF-β signaling and activating BMP signaling.

Aberrant hypomethylated STAT3 was identified as a biomarker of chronic benzene poisoning through integrating DNA methylation and mRNA expression data

Chronic occupational benzene exposure is associated with an increased risk of hematological malignancies such as aplastic anemia and leukemia. The new biomarker and action mechanisms of chronic benzene poisoning are still required to be explored. Aberrant DNA methylation, which may lead to genomic instability and the altered gene expression, is frequently observed in hematological cancers. To gain an insight into the new biomarkers and molecular mechanisms of chronic benzene poisoning, DNA methylation profiles and mRNA expression pattern from the peripheral blood mononuclear cells of four chronic benzene poisoning patients and four health controls that matched age and gender without benzene exposure were performed using the high resolution Infinium 450K methylation array and Gene Chip Human Gene 2.0ST Arrays, respectively. By integrating DNA methylation and mRNA expression data, we identified 3 hypermethylated genes showing concurrent down-regulation (PRKG1, PARD3, EPHA8) and 2 hypomethylated genes showing increased expression (STAT3, IFNGR1). Signal net analysis of differential methylation genes associated with chronic benzene poisoning showed that two key hypomethylated STAT3 and hypermethylated GNAI1 were identified. Further GO analysis and pathway analysis indicated that hypomethylated STAT3 played central roles through regulation of transcription, DNA-dependent, positive regulation of transcription from RNA polymerase II promoter, JAK-STAT cascade and adipocytokine signaling pathway, Acute myeloid leukemia, and JAK-STAT signaling pathway. In conclusion, the aberrant hypomethylated STAT3 might be a potential biomarker of chronic benzene poisoning.