Perchlorate-induced oxidative stress in isolated liver mitochondria

Exploring cell aggregation as a defense strategy against perchlorate stress in Chlamydomonas reinhardtii through multi-omics analysis

Perchlorate (ClO4-) is a type of novel, widely distributed, and persistent inorganic pollutant. However, the impacts of perchlorate on freshwater algae remain unclear. In this study, the response and defense mechanisms of microalgae (Chlamydomonas reinhardtii) under perchlorate stress were investigated by integrating physiological and biochemical monitoring, transcriptomics, and metabolomics. Weighted gene co-expression network analysis (WGCNA) of transcriptome data was used to analyze the relationship between genes and phenotype and screen the key pathways. C. reinhardtii exhibited aggregate behavior when exposed to 100- and 200-mM perchlorate but was restored to its unicellular lifestyle when transferred to fresh medium. WGCNA results found that the "carbohydrate metabolism" and "lipid metabolism" pathways were closely related to cell aggregation phenotype. The differential expression genes (DEGs) and differentially accumulated metabolites (DAMs) of these pathways were upregulated, indicating that the lipid and carbohydrate metabolisms were enhanced in aggregated cells. Additionally, most genes and metabolites related to phytohormone abscisic acid (ABA) biosynthesis and the mitogen-activated protein kinase (MAPK) signaling pathway were significantly upregulated, indicating their crucial roles in the signal transmission of aggregated cells. Meanwhile, in aggregated cells, extracellular polymeric substances (EPS) and lipid contents increased, photosynthesis activity decreased, and the antioxidant system was activated. These characteristics contributed to C. reinhardtii's improved resistance to perchlorate stress. Above results demonstrated that cell aggregation behavior was the principal defense strategy of C. reinhardtii against perchlorate. Overall, this study sheds new light on the impact mechanisms of perchlorate to aquatic microalgae and provides multi-omics insights into the research of multicellular-like aggregation as an adaptation strategy to abiotic stress. These results are beneficial for assessing the risk of perchlorate in aquatic environments.

Associations of perchlorate, nitrate, and thiocyanate with metabolic syndrome and its components among US adults: A cross-sectional study from NHANES

Perchlorate, nitrate and thiocyanate are common endocrine disruptors. Herein, this study was undertaken to evaluate the associations between perchlorate, nitrate, and thiocyanate exposures (alone or in combination) and risk of metabolic syndrome (MetS) among adults, which has not been explored so far. Analytical data were extracted from different datasets in the National Health and Nutrition Examination Survey (NHANES) database. Multivariate logistic regression models were constructed to investigate the associations between perchlorate, nitrate, and thiocyanate exposures, and the prevalence of MetS. Subsequently, odds ratios (OR) and their corresponding 95 % confidence intervals (CIs) were adopted to represent the magnitude of the effect size. We performed a series of subgroup analyses and sensitivity analyses as well. Moreover, three commonly used mixture modeling strategies [Weighted quantile sum (WQS) regression, quantile-based g-computation (Qgcomp), and Bayesian kernel machine regression (BKMR)] were utilized to evaluate the joint mixture effect on MetS. This study included 12,007 participants in the subsequent analyses. After adjustment for confounding factors, higher levels of perchlorate, and thiocyanate concentrations were significantly associated with the risk of MetS (OR = 1.15, 95%CI:1.00, 1.32; OR = 1.21, 95%CI:1.04, 1.41, respectively). Analyses of WQS and Qgcomp showed that a quartile increase in chemical mixture was correlated with the occurrence of MetS with ORs of 1.07 (95%CI: 0.99, 1.16) and 1.07 (95%CI: 1.00, 1.14), respectively. This positive association was mainly driven by perchlorate and thiocyanate. Analysis of BKMR revealed that perchlorate, nitrate, and thiocyanate mixture was positively associated with the risk of MetS while perchlorate, and thiocyanate were major predictors in the mixture. In summary, our study reveals positive relationships between perchlorate, thiocyanate and MetS. Co-exposure to perchlorate, nitrate and thiocyanate is positively associated with the risk of MetS, with perchlorate and thiocyanate contributing the most to the overall mixture effect.

Environmental exposure to perchlorate, nitrate, and thiocyanate in relation to chronic kidney disease in the general US population, NHANES 2005-2016

BACKGROUND

Few studies have explored the impact of perchlorate, nitrate, and thiocyanate (PNT) on kidney function. This study aimed to evaluate the association of urinary levels of PNT with renal function as well as the prevalence of chronic kidney disease (CKD) among the general population in the United States.

METHODS

This analysis included data from 13,373 adults (≥20 years) from the National Health and Nutrition Examination Survey 2005 to 2016. We used multivariable linear and logistic regression, to explore the associations of urinary PNT with kidney function. Restricted cubic splines were used to assess the potentially non-linear relationships between PNT exposure and outcomes.

RESULTS

After traditional creatinine adjustment, perchlorate (P-traditional) was positively associated with estimated glomerular filtration rate (eGFR) (adjusted β: 2.75; 95% confidence interval [CI]: 2.25 to 3.26; P < 0.001), and negatively associated with urinary albumin-to-creatinine ratio (ACR) (adjusted β: -0.05; 95% CI: -0.07 to -0.02; P = 0.001) in adjusted models. After both traditional and covariate-adjusted creatinine adjustment, urinary nitrate and thiocyanate were positively associated with eGFR (all P values <0.05), and negatively associated with ACR (all P values <0.05); higher nitrate or thiocyanate was associated with a lower risk of CKD (all P values <0.001). Moreover, there were L-shaped non-linear associations between nitrate, thiocyanate, and outcomes. In the adjusted models, for quartiles of PNT, statistically significant dose-response associations were observed in most relationships. Most results were consistent in the stratified and sensitivity analyses.

CONCLUSIONS

Exposures to PNT might be associated with kidney function, indicating a potential beneficial effect of environmental PNT exposure (especially nitrate and thiocyanate) on the human kidney.

Perchlorate, nitrate, and thiocyanate and depression: the potential mediating role of sleep

Perchlorate, nitrate, and thiocyanate are common thyroid disruptors, but it is not clear whether they are related to depression. In this study, we aimed to investigate the association between perchlorate, nitrate, and thiocyanate and depression, and to explore the potential role of sleep in this process. We used data from the National Health and Nutrition Examination Survey (NHANES). From 2005 to 2016, 6 cycles cross-sectional data were combined. Urinary perchlorate, nitrate, and thiocyanate came from laboratory test; depression was diagnosed by the Nine-item Patient Health Questionnaire (PHQ-9). Weighted generalized liner models, restricted cubic splines, and mediation analysis were used in this study. Totally, 16,715 participants were involved in this study, of which 8295 (49.63%) were male and 8420 (50.37%) were female, with an average age of 46.19 ± 0.32 years. We found that urinary thiocyanate concentration was positively associated with depression (Odds ratios [ORs]: 1.49; 95% confidence intervals [95% CIs]: 1.16, 1.91), but not perchlorate (ORs: 0.71; 95% CIs: 0.52, 0.97) or nitrate (ORs: 0.89, 95% CIs: 0.66, 1.19). Sleep may play a potential mediating role between thiocyanate and depression (9.55%). In conclusion, higher concentrations of thiocyanate exposure may be associated with a higher risk of depression, and the sleep duration may be an important mediating factor.

Perchlorate-Specific Proteomic Stress Responses of Debaryomyces hansenii Could Enable Microbial Survival in Martian Brines

If life exists on Mars, it would face several challenges including the presence of perchlorates, which destabilize biomacromolecules by inducing chaotropic stress. However, little is known about perchlorate toxicity for microorganism on the cellular level. Here we present the first proteomic investigation on the perchlorate-specific stress responses of the halotolerant yeast Debaryomyces hansenii and compare these to generally known salt stress adaptations. We found that the responses to NaCl and NaClO₄ -induced stresses share many common metabolic features, e.g., signaling pathways, elevated energy metabolism, or osmolyte biosynthesis. Nevertheless, several new perchlorate-specific stress responses could be identified, such as protein glycosylation and cell wall remodulations, presumably in order to stabilize protein structures and the cell envelope. These stress responses would also be relevant for life on Mars, which - given the environmental conditions - likely developed chaotropic defense strategies such as stabilized confirmations of biomacromolecules and the formation of cell clusters. This article is protected by copyright. All rights reserved.

Environmental thiocyanate exposure was associated with oral health-related productivity loss among US adults: results from NHANES

The aim of this study is to examine the environmental exposure to perchlorate, nitrate, and thiocyanate and their associations with oral health-related productivity loss (PL) in general population. A total of 13,554 participants were enrolled from the National Health and Nutrition Examination Survey. Urinary perchlorate, nitrate, and thiocyanate were measured using ion chromatography coupled with electrospray tandem mass spectrometry. Multivariable linear and logistic regressions were performed to explore the associations between urinary perchlorate, nitrate, and thiocyanate with the prevalence of PL. Restricted cubic splines were used to explore the nonlinearity. There are 636 PL cases. There was higher urinary level of thiocyanate in PL group. We found that compared with the lowest quartile, thiocyanate was associated with PL (odds ratio 0.72, 95% confidence interval [0.53, 0.98]; p = 0.039) in the highest quartile. Restricted cubic spines reveled that urinary thiocyanate was L-shaped associated with PL with the infection point of 1.35. Urinary thiocyanate was L-shaped associated with PL with the infection point of 1.35.

The Association Between Environmental Perchlorate, Nitrate, and Thiocyanate Exposure and Oral Pain in NHANES

Aim

To examine the human exposure to perchlorate, nitrate, and thiocyanate, and their associations with oral pain (OP) in the general population from the U.S.

Methods

A total of 13,554 participants were enrolled in the National Health and Nutrition Examination Survey. The urinary perchlorate, nitrate, and thiocyanate were measured using ion chromatography coupled with an electrospray tandem mass spectrometry. The multivariable linear and logistic regressions were performed to explore the associations of the urinary perchlorate, nitrate, and thiocyanate, with the prevalence of oral pain. Restricted cubic splines were used to explore the non-linearity.

Results

There are 3,129 OP cases. There was a higher urinary level of perchlorate, nitrate, and thiocyanate in OP. We found that urinary thiocyanate was positively associated with OP (odds ratio [OR] = 1.06; [1, 1.13]; p = 0.049). Restricted cubic spines revealed that urinary thiocyanate was in a U-shape association with OP.

Conclusions

Urinary thiocyanate was in a U-shape association with OP, suggesting that we should keep the exposure of thiocyanate under a reasonable range.

The association between environmental exposure to perchlorate, nitrate, and thiocyanate and all-cause and cause-specific mortality

The aim is to examine the environmental exposure to perchlorate, nitrate, and thiocyanate and their associations with all-cause and cause-specific mortality in a general population. A total of 17,982 participants were enrolled from the National Health and Nutrition Examination Survey and urinary perchlorate, nitrate, and thiocyanate are measured using ion chromatography coupled with electrospray tandem mass spectrometry. Multivariable linear and logistic regression models were performed to explore the associations between urinary perchlorate, nitrate, and thiocyanate with all-cause and cause-specific mortality. Restricted cubic spline models were used to explore the nonlinearity. During a 7.5-year of follow-up, 1730 deaths occurred. Kaplan-Meier analysis suggested that urinary perchlorate, thiocyanate, and nitrate were associated with all-cause mortality (all log-rank P<0.001). After adjusted for traditional risk factors, we found that urinary perchlorate was inversely associated with cancer mortality (hazard ratio [HR] 0.87; 95% confidence interval [0.76, 0.99]; P=0.038) while nitrate was positively related to cancer mortality (HR 1.19, [1.05, 1.34]; P=0.006). Besides, urinary thiocyanate exposure was U-shape associated with the risk of all-cause mortality (P for nonlinearity<0.001). Urinary perchlorate was inversely while nitrate was positively associated with the risk of cancer mortality. The thiocyanate exposure was U-shape associated with the risk of all-cause mortality.

Exposure to perchlorate, nitrate and thiocyanate was associated with the prevalence of cardiovascular diseases

AIMS

To determine the association between urinary levels of perchlorate, nitrate and thiocyanate, and the prevalence of cardiovascular diseases (CVD) among general population.

METHODS

A total of 16, 570 participants were enrolled from the National Health and Nutrition Examination Surveys (NHANES). Urinary levels of perchlorate, nitrate and thiocyanate were measured using ion chromatography coupled with electrospray tandem mass spectrometry. Multivariable linear regressions and logistic regressions were performed to explore the associations of exposure to perchlorate, nitrate and thiocyanate, and the prevalence of total and specific CVD, including chronic heart failure (CHF), coronary heart disease (CHD), angina, heart failure and stroke. Restricted cubic splines were used to explore the nonlinearity.

RESULTS

Participants with CVD had a lower urinary level of nitrate and thiocyanate (all P < 0.001). A null association between urinary perchlorate and total CVD or specific CVD was observed. Comparing with the lowest quartile, the highest quartile of urinary nitrate was independently associated with a decreased presence of total CVD (odds ratio [OR] 0.66, 95% confidence interval [CI] [0.53, 0.82]), CHF (OR 0.48, 95% CI [0.33, 0.71]), and stroke (OR 0.63, 95%CI [0.45, 0.88]). In addition, per one-fold increasement of urinary nitrate decreased a 0.15-fold prevalence of total CVD, 0.29-fold prevalence of CHF, and 0.16-fold prevalence of stroke. However, for urinary thiocyanate, we found that the 2nd and 3rd quartile were associated with total CVD, the 2nd quartile associated with heart attack, and the 2nd, 3rd and 4th quartile associated with stroke. What's more, restricted cubic splines confirmed that the relation between urinary nitrate and CVD was linear (P for nonlinearity = 0.242) and the inverse relation between urinary thiocyanate and CVD was nonlinear (P for nonlinearity < 0.001).

CONCLUSION

In the general population, low levels of nitrate were linearly while thiocyanate were nonlinearly associated with an increased presence of cardiovascular diseases.

Apoptotic endocrinal toxic effects of perchlorate in human placental cells

BACKGROUND

Perchlorate is a strong oxidizing agent and has many adverse health effects. This study investigated the potential oxidative, apoptotic, and endocrinal toxic effects of perchlorate in human placenta-derived mesenchymal stem cells (HP-MSCs).

METHODS

HP-MSCs were treated with two doses of perchlorate (5 and 15 μg/L) for three days. The perchlorate's effects were detected by histopathological examination, aromatase/CYP19 A1 activity, reactive oxygen species production (ROS), and Caspase-3 expression.

RESULTS

The highest perchlorate concentration (15 μg/L) caused significant placental histopathological changes. The placental cell viability was significantly affected by a significant increase in ROS generation; caspase-3 expression, and a significant reduction of CYP 19 activity. Despite the slight induction effect of the lowest perchlorate concentration (5 μg/L) on caspase 3 expression, CYP 19 activity, and ROS generation, it did not affect placental cellular viability.

CONCLUSION

This study suggested that perchlorate could modulate aromatase activity and placental cytotoxicity. The continuous monitoring of the actual perchlorate exposure is needed and could be cost-effective.

Perchlorate detection via an invertebrate biosensor

Improvised explosive devices (IEDs) are constructed from easily obtainable ingredients that are often unregulated and difficult to trace. Salts of the oxyhalide perchlorate are frequently used as oxidisers in IEDs and in commercially available munitions, thus a reliable detection is needed to aid forensic investigations and the tracing of environmental ground or surface water contamination. We introduce the nematode Caenorhabditis elegans as a biosensor for the presence of perchlorate, a promising alternative to the costly, technically challenging and time-consuming current perchlorate detection methods. Perchlorate uptake dynamics in C. elegans were first validated using ion exchange chromatography followed by assessing the effects of perchlorate on key life-point indices to verify the suitability of the nematodes as a forensic biosensor. Whole genome microarrays and qPCR analyses established that a set of immune and stress response genes were enriched during perchlorate exposure. A nematode strain (agIs219) containing an integrated copy of the significantly overexpressed t24b8.5 gene promoter followed by a GFP reporter gene was shown to fluoresce in a perchlorate dose dependent manner with a limit of detection (LOD) of 0.5 mg mL-1. Whilst chemicals commonly used in the construction of IEDs did not induce fluorescence, exposure to other oxyhalides did, highlighting the presence of possible shared stress response pathways. Burnt wire sparklers containing potassium perchlorate elicited fluorescence while other non-perchlorate containing post-blast explosion matrices did not. This demonstrates how C. elegans can be used to screen for perchlorate at environmental hotspots, an optimization, possibly with other target transgenes, is required to enable the detection of perchlorate at concentrations below 0.5 mg mL-1.

Anion-templated assembly of multinuclear copper(ii)–triazole complexes

Anions were used as templates to construct copper(ii) clusters with different architectures.

Modulation of mitochondrial functions by xenobiotic-induced microRNA: From environmental sentinel organisms to mammals

Mitochondria play a crucial role in energetic metabolism, signaling pathways, and overall cell viability. They are in the first line in facing cellular energy requirements in stress conditions, such as in response to xenobiotic exposure. Recently, a novel regulatory key role of microRNAs (miRNAs) in important signaling pathways in mitochondria has been proposed. Consequently, alteration in miRNAs expression by xenobiotics could outcome into mitochondrial dysfunction, reactive oxygen species overexpression, and liberation of apoptosis or necrosis activating proteins. The aim of this review is to show the highlights about mitochondria-associated miRNAs in cellular processes exposed to xenobiotic stress in different cell types involved in detoxification processes or sensitive to environmental hazards in marine sentinel organisms and mammals.

Ecotoxicological assessment of perchlorate using in vitro and in vivo assays

Perchlorate is an inorganic ion widespread in the environment, generated as a natural and anthropogenic pollutant, with known endocrine disruption properties in the thyroid gland. Nonetheless, there are few reports of its ecotoxicological impact on wildlife. The aim of this study was to evaluate the adverse effects of KClO₄ exposure on different cell lines, HEK, N2a, and 3T3, as well as in ecological models such as Vibrio fischeri, Pseudokirchneriella subcapitata, Daphnia magna, and Eisenia fetida. Perchlorate exhibited similar toxicity against tested cell lines, with LC₅₀ values of 19, 15, and 19 mM for HEK, N2a, and 3T3, respectively; whereas in V. fischeri, the toxicity, examined as bioluminescence reduction, was considerably lower (EC₅₀ = 715 mM). The survival of the freshwater algae P. subcapitata was significatively impaired by perchlorate (LC₅₀ = 72 mM), and its effect on the lethality in the crustacean D. magna was prominent (LC₅₀ = 5 mM). For the earthworm E. fetida, the LC₅₀ was 56 mM in soil. In this organism, perchlorate induced avoidance behavior, weight loss, and decreased egg production and hatchling, as well as morphological and histopathological effects, such as malformations, dwarfism, and necrosis. In conclusion, perchlorate toxicity varies according to the species, although E. fetida is a sensitive model to generate information regarding the toxicological impact of KClO₄ on biota.

Evaluation of hypothalamus-pituitary-thyroid axis function by chronic perchlorate exposure in male rats

Perchlorate is a widespread endocrine disruptor that was previously correlated with increased serum TSH levels and decreased thyroid hormones production both in animals and humans. Even so, the regulation of gene/protein expression in the hypothalamus, pituitary and thyroid by chronic perchlorate exposure was not completely elucidated. Therefore, this study aimed to investigate the underlying mechanisms involved in the disruption of hypothalamus-pituitary-thyroid axis by chronic perchlorate exposure. Male Wistar rats were treated or not with NaClO₄ in the drinking water (35 mg/Kg/day) for 60 days. Thereafter, hormone/cytokines serum levels were measured through multiplex assays; genes/proteins expression were investigated by qPCR/Western Blotting and thyroid morphology was evaluated through histological analysis. Serum TSH levels were increased and serum T₄ /T₃ levels were decreased in perchlorate-treated animals. This treatment also altered the thyrotropin-releasing hormone mRNA/protein content in the hypothalamus. Additionally, the expression of both subunits of TSH were increased in the pituitary of perchlorate-treated rats, which also presented significant alterations in the thyroid morphology/gene expression. Furthermore, perchlorate exposure reduced liver Dio1 mRNA expression and increased the content of pro-inflammatory cytokines in the thyroid and the serum. In conclusion, our study adds novel findings about the perchlorate-induced disruption of the hypothalamus-pituitary-thyroid axis gene/protein expression in male rats. The data presented herein also suggest that perchlorate induces thyroid and systemic inflammation through the increased production of cytokines. Taken together, our results suggest that perchlorate contamination should be monitored, especially in the individuals most susceptible to the deleterious effects of reduced levels of thyroid hormones.

Exposure to perchlorate, nitrate and thiocyanate, and prevalence of diabetes mellitus

Background

It is known that perchlorate, nitrate and thiocyanate have the property of inhibiting sodium iodide symporter. Animal studies have suggested that these compounds, especially perchlorate, might also interfere with insulin secretion. However, the association between their exposure and diabetes risk is largely unknown in humans.

Methods

Among 11 443 participants (mean age 42.3 years) from the National Health and Nutritional Examination Survey 2001-14, urinary perchlorate, nitrate and thiocyanate were measured by using ion chromatography coupled with electrospray tandem mass spectrometry. Diabetes was defined as self-reported doctor diagnosis, use of oral hypoglycaemic medication or insulin, fasting plasma glucose ≥ 126 mg/dl or glycated haemoglobin A1c (HbA1c) ≥ 6.5%.

Results

The median (interquartile range) levels of urinary perchlorate, nitrate and thiocyanate were 3.32 (1.84, 5.70) μg/l, 46.4 (27.9, 72.0) mg/l and 1.23 (0.59, 2.78) mg/l, respectively. Higher levels of urinary perchlorate were associated with elevated levels of fasting glucose, HbA1c, insulin and homeostatic model assessment of insulin resistance (all Ptrend < 0.001). After multivariate adjustment including urinary creatinine, smoking status and body mass index (BMI), higher urinary perchlorate, but not nitrate or thiocyanate, was associated with an increased prevalence of diabetes mellitus. Comparing extreme quintiles, the odds ratio (95% confidence interval) of diabetes was 1.53 (1.21, 1.93; Ptrend < 0.001) for perchlorate, 1.01 (0.77, 1.32; Ptrend = 0.44) for nitrate and 0.98 (0.73, 1.31; Ptrend = 0.64) for thiocyanate. When urinary perchlorate, nitrate and thiocyanate were further mutually adjusted, the results did not materially change. Similar results were observed when analyses were stratified by smoking status, as well as by age, gender, kidney function and BMI.

Conclusions

Higher urinary perchlorate levels are associated with an increased prevalence of diabetes mellitus, independent of traditional risk factors. Future prospective studies are needed to confirm these findings.