Long-term exposure to crotonaldehyde causes heart and kidney dysfunction through induction of inflammatory and oxidative damage in male Wistar rats

Exposure to Volatile Organic Compounds in Relation to Visceral Adiposity Index and Lipid Accumulation Product Among U.S. Adults: NHANES 2011-2018

Volatile organic compounds (VOCs) are associated with obesity health risks, while the association of mixed VOCs with visceral adiposity indicators remains unclear. In this study, a total of 2015 adults from the National Health and Nutrition Examination Survey (NHANES) were included. Weighted generalized linear models, restricted cubic spline (RCS), weighted quantile sum (WQS), and Bayesian kernel machine regression (BKMR) were adopted to assess the association of VOC metabolites (mVOCs) with the visceral adiposity index (VAI) and lipid accumulation product (LAP). Multiple mVOCs were positively associated with the VAI and LAP in the single-exposure model, especially N-acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA) and N-acetyl-S-(N-methylcarbamoyl)-L-cysteine (AMCC). The associations of mVOCs with VAI and LAP were more significant in <60-year-old and non-obese individuals, with interactions of CEMA with age and AMCC with obesity status. Nonlinear relationships between certain mVOCs and the VAI or the LAP were also observed. In the WQS model, co-exposure to mVOCs was positively correlated with the VAI [β (95%CI): 0.084 (0.022, 0.147)]; CEMA (25.24%) was the major contributor. The result of the BKMR revealed a positive trend of the association between mixed mVOCs and the VAI. Our findings suggest that VOC exposure is strongly associated with visceral obesity indicators. Further large prospective investigations are necessary to support our findings.

Sexual dimorphism association of combined exposure to volatile organic compounds (VOC) with kidney damage

BACKGROUND

Epidemiological evidence emphasizes air pollutants' role in chronic kidney disease (CKD). Volatile organic compounds (VOCs) contribute to air pollution, yet research on VOCs and kidney damage, especially gender disparities, is limited.

METHODS

This study analyzed NHANES data to explore associations between urinary VOC metabolite mixtures (VOCMs) and key kidney-related parameters: estimated glomerular filtration rate (eGFR), albumin-to-creatinine ratio (ACR), chronic kidney disease (CKD), and albuminuria. Mediation analyses assessed the potential mediating roles of biological aging (BA) and serum albumin in VOCM mixtures' effects on kidney damage. Sensitivity analyses were also conducted.

RESULTS

The mixture analysis unveiled a noteworthy positive association between VOCM mixtures and the risk of developing CKD, coupled with a significant negative correlation with eGFR within the overall participant cohort. These findings remained consistent when examining the female subgroup. However, among male participants, no significant link emerged between VOCM mixtures and CKD or eGFR. Furthermore, in both the overall and female participant groups, there was an absence of a significant correlation between VOCM mixtures and either ACR or albuminuria. On the other hand, in male participants, while no significant correlation was detected with albuminuria, a significant positive correlation was observed with ACR. Pollutant analysis identified potential links between kidney damage and 1,3-butadiene, toluene, ethylbenzene, styrene, xylene, acrolein, crotonaldehyde and propylene oxide. Mediation analyses suggested that BA might partially mediate the relationship between VOCM mixtures and kidney damage.

CONCLUSION

The current findings highlight the widespread exposure to VOCs among the general U.S. adult population and indicate a potential correlation between exposure to VOC mixtures and compromised renal function parameters, with notable gender disparities. Females appear to exhibit greater sensitivity to impaired renal function resulting from VOCs exposure. Anti-aging treatments may offer some mitigation against kidney damage due to VOCs exposure.

Association of volatile organic compound exposure with metabolic syndrome and its components: a nationwide cross-sectional study

BACKGROUND

Metabolic syndrome (MetS) is a health issue consisting of multiple metabolic abnormalities. The impact of exposure to volatile organic compounds (VOCs) on MetS and its components remains uncertain. This study aimed to assess the associations of individual urinary metabolites of VOC (mVOCs) and mVOC mixtures with MetS and its components among the general adult population in the United States.

METHODS

A total of 5345 participants with eligible data were filtered from the 2011-2020 cycles of the National Health and Nutrition Examination Survey. Multivariate logistic regression models were applied to assess the associations of individual mVOCs with MetS and its components. The least absolute shrinkage and selection operator (LASSO) regression models were constructed to identify more relevant mVOCs. The weight quantile sum regression model was applied to further explore the links between mVOC co-exposure and MetS and its components.

RESULTS

The results indicated positive associations between multiple mVOCs and MetS, including CEMA, DHBMA, and HMPMA. CEMA was found to be positively correlated with all components of MetS. HMPMA was associated with elevated triglyceride (TG), reduced high-density lipoprotein, and fasting blood glucose (FBG) impairment; 3HPMA was associated with an elevated risk of high TG and FBG impairment; and DHBMA had positive associations with elevated TG and high blood pressure. The co-exposure of LASSO-selected mVOCs was associated with an increased risk of elevated TG, high blood pressure, and FBG impairment.

CONCLUSION

Positive associations of certain individual urinary mVOCs and mVOC mixtures with MetS and its components were observed by utilizing multiple statistical models and large-scale national data. These findings may serve as the theoretical basis for future experimental and mechanistic studies and have important implications for public health.

Crotonaldehyde induced structural alterations in Low-Density Lipoprotein: Immunogenicity of the modified protein in experimental animals and auto-antibodies generation in various cancers

Crotonaldehyde (CA), a prominent component of cigarette smoke (CS) is a pervasive environmental pollutant that is a highly toxic, unsaturated aldehyde. Exposure to CA-rich pollutants has been linked to the emergence of many malignancies in humans. To better understand the role of CA in biomolecule modification, this study investigated the detailed structural alterations in low-density lipoprotein (LDL) modified by CA, as well as the immunogenicity of the modified protein in experimental animals and the search for autoantibodies in various cancers patients.In vitro, results indicated alterations in secondary and tertiary structures; examined using UV-visible, fluorescence, far-UV circular dichroism, and Fourier transform infrared spectroscopy techniques. Changes in the oxidation status of LDL were studied by carbonyl content assay and NBT assay. ThT binding assay, scanning, and transmission electron microscopy were used to study aggregate formation. The findings revealed significant structural damage in LDL modified by CA. The modification resulted in the unmasking of hydrophobic clusters, the loss of the protein α-helix, and the formation of β-pleated sheet structure. The amyloid aggregate formation was confirmed through ThT microscopy and electron spectroscopy. Rabbits immunized with crotonaldehyde; lead to structural changes in the LDL; that acted as extra antigenic determinants, eliciting strong antibody response. Immunoglobulin response is highly specific for modified LDL as demonstrated by the ELISA. The presence of antibodies against CA-modified LDL was confirmed by the immunoglobulin content of blood sera from human subjects with lung cancer, and competitive ELISA demonstrated the specificity of these antibodies. This study offers insights into the CA-mediated LDL modification and immunogenicity in lung cancer that will have diagnostic importance.

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 exposure to volatile organic compounds and serum lipids in the US adult population

BACKGROUND AND AIM

Epidemiological evidence on the relationship between exposure to volatile organic compounds (VOCs), both single and mixed, and serum lipid levels is limited, and their relationship remains unclear. Our study aimed to investigate the associations of exposure to VOCs with serum lipid levels in the US adult population.

METHODS AND RESULTS

The study examined the association of 16 VOC levels (2-methylhippuric acid, 3- and 4-methylhippuric acid, N-acetyl-S-(2-carbamoylethyl)-L-cysteine, N-acetyl-S-(N-methylcarbamoyl)-L-cysteine, 2-aminothiazoline-4-carboxylic acid, N-acetyl-S-(benzyl)-L-cysteine, N-acetyl-S-(n-propyl)-L-cysteine, N-acetyl-S-(2-carboxyethyl)-L-cysteine, N-acetyl-S-(2-cyanoethyl)-L-cysteine, N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine, N-acetyl-S-(2-hydroxypropyl)-L-cysteine. N-Acetyl-S-(3-hydroxypropyl)-L-cysteine, mandelic acid, N-acetyl-S-(4-hydroxy-2-butenyl)-L-cysteine, phenylglyoxylic acid and N-acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine) with total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL) using data from the National Health and Nutrition Examination Survey (NHANES) between 2011 and 2015, and a total of 1410 adults were enrolled. The association was evaluated by Bayesian kernel machine regression (BKMR), multiple linear regression and weighted quantile sum (WQS) regression. In BKMR analysis, exposure to VOCs is positively correlated with levels of TC, TG, and LDL-C. However, statistical significance was observed only for the impact on TG. Our linear regression analysis and WQS regression generally support the BKMR results. Several VOCs were positively associated with serum lipid profiles (e.g., the ln-transformed level of mandelic acid (MA) displayed an increase in estimated changes of 7.01 (95% CIs: 2.78, 11.24) mg/dL for TC level), even after the effective number of tests for multiple testing (P < 0.05).

CONCLUSIONS

Exposure to VOCs was associated with serum lipids, and more studies are needed to confirm these findings.

Antioxidant potential of Pediococcus pentosaceus strains from the sow milk bacterial collection in weaned piglets

BACKGROUND

In modern animal husbandry, breeders pay increasing attention to improving sow nutrition during pregnancy and lactation to favor the health of neonates. Sow milk is a main food source for piglets during their first three weeks of life, which is not only a rich repository of essential nutrients and a broad range of bioactive compounds, but also an indispensable source of commensal bacteria. Maternal milk microorganisms are important sources of commensal bacteria for the neonatal gut. Bacteria from maternal milk may confer a health benefit on the host.

METHODS

Sow milk bacteria were isolated using culturomics followed by identification using 16S rRNA gene sequencing. To screen isolates for potential probiotic activity, the functional evaluation was conducted to assess their antagonistic activity against pathogens in vitro and evaluate their resistance against oxidative stress in damaged Drosophila induced by paraquat. In a piglet feeding trial, a total of 54 newborn suckling piglets were chosen from nine sows and randomly assigned to three treatments with different concentrations of a candidate strain. Multiple approaches were carried out to verify its antioxidant function including western blotting, enzyme activity analysis, metabolomics and 16S rRNA gene amplicon sequencing.

RESULTS

The 1240 isolates were screened out from the sow milk microbiota and grouped into 271 bacterial taxa based on a nonredundant set of 16S rRNA gene sequencing. Among 80 Pediococcus isolates, a new Pediococcus pentosaceus strain (SMM914) showed the best performance in inhibition ability against swine pathogens and in a Drosophila model challenged by paraquat. Pretreatment of piglets with SMM914 induced the Nrf2-Keap1 antioxidant signaling pathway and greatly affected the pathways of amino acid metabolism and lipid metabolism in plasma. In the colon, the relative abundance of Lactobacillus was significantly increased in the high dose SMM914 group compared with the control group.

CONCLUSION

P. pentosaceus SMM914 is a promising probiotic conferring antioxidant capacity by activating the Nrf2-Keap1 antioxidant signaling pathway in piglets. Our study provided useful resources for better understanding the relationships between the maternal microbiota and offspring. Video Abstract.

Diurnal variability in urinary volatile organic compound metabolites and its association with oxidative stress biomarkers

Volatile organic compounds (VOCs) are ubiquitous environmental pollutants that are associated with birth defects, leukemia, neurocognitive deficits, reproductive impairment and cancer in humans exposed to these compounds. Exposure to VOCs can be assessed by measuring their metabolites in urine. Little is known, however, about the temporal variability in urinary VOC metabolite (VOCM) concentrations within- and between-individuals. In this study, we determined the variability in the concentrations of 38 VOCMs in urine samples collected from 19 healthy individuals across a period of 44 days. We also measured seven biomarkers of oxidative stress (lipid, protein and DNA damage) in urine to assess the relationship of VOC exposure to oxidative stress. Seventeen VOCMs had detection frequencies (DFs) of >60% in urine, and we limited further data analysis to those compounds. The creatinine-adjusted geometric mean concentrations of VOCMs ranged from 2.70 μg/g to 327 μg/g in spot and 2.60 μg/g to 551 μg/g in first morning void (FMV) urine samples. Calculation of the intra-class correlation coefficients (ICCs) for 17 VOCM concentrations to assess their predictability and repeatability in urinary measurements showed ranges of 0.080-0.425 in spot and 0.050-0.749 in FMV urine samples, revealing notable within-individual variability. Our results suggest that taking only single measurements of VOCM concentrations in urine in epidemiological investigations may lead to exposure misclassification. In addition, VOCM concentrations were significantly and positively correlated with oxidative stress biomarkers. This study thus provides important information for formulating sampling strategies in the biomonitoring of VOC exposure in human populations.

Triptolide regulates oxidative stress and inflammation leading to hepatotoxicity via inducing CYP2E1

Triptolide (TP), the main active compound extracted from medicine-tripterygium wilfordii Hook f. (TWHF). It has anti-tumor and immunomodulatory properties. Our study aimed to investigate the mechanisms of hepatotoxicity treated with TP in vivo and in vitro, as well as their relationship with the NF-κB (p65) signal pathway; and to assess TP-induced hepatotoxicity after CYP2E1 modulation by the known inhibitor, clomethiazole, and the known inducer, pyrazole. Mice were given TP to cause liver injury and IHHA-1 cells were given TP to cause hepatocyte injury. The enzyme activity and hepatotoxicity changed dramatically when the CYP2E1 inhibitor and inducer were added. In comparison to the control group, the enzyme inducer increased the activity of CYP2E1, whereas the enzyme inhibitor had the opposite effect. Our findings suggest that TP is an inducer of CYP2E1 via a time-dependent activation mechanism. In addition, TP can promote oxidative stress, inflammatory and involving the NF-κB (p65) signal pathway. Therefore, we used triptolide to stimulate C57 mice and IHHA-1 cells to determine whether TP can promote oxidative stress and inflammation by activating CYP2E1 in response to exacerbated liver damage and participate in NF-κB (p65) signaling pathway.

Atmospheric ozonolysis of crotonaldehyde in the absence and presence of hydroxylated silica oligomer cluster adsorption

As one of the main components of combustion of tobacco products occurs (CARB), crotonaldehyde has an acute toxicity and widely exists in the atmosphere, which is harmful to human health. The removal efficiency of VOCs by ozonation can reach 80-90%. Based on the theory of quantum chemistry, the degradation mechanism, kinetics and toxicity of crotonaldehyde by ozonation in gas phase and heterogeneous phase were studied. Ozone was added to the olefins unsaturated double bond to form a five-membered ring primary ozonide, which was further fractured due to its unstable structure to form a Criegee intermediate and an aldehyde compound. The reaction rate constant of crotonaldehyde with ozone was 1.24 × 10^-17 cm³ molecule^-1 s^-1 at 298 K and 1 atm, which was an order of magnitude higher than the experimental value. From toxicity assessment, it was found that the ozonation of crotonaldehyde is beneficial to the removal of toxicity. Mineral dust aerosol exists in the atmosphere in large quantities, and SiO₂ is the most abundant component. VOCs are transformed into particle state on their surface through homogeneous nucleation and heterogeneous nucleation. Referring to the crystal structure of SiO₂, five hydroxylated silica oligomer cluster structures were simulated and the adsorption configurations of crotonaldehyde on their surface were simulated. The adsorption of crotonaldehyde on the surface of the clusters was achieved by forming hydrogen bonds and had good adsorption effects. The adsorption of hydroxylated silica oligomer clusters didn't change the ozonation mechanism of crotonldehyde, but had a certain effect on the reaction rate.

Crotonaldehyde exposure induces liver dysfunction and mitochondrial energy metabolism disorder in rats

Crotonaldehyde is a highly toxic pollutant, widely present in tobacco smoke and automobile exhaust. Exposure to crotonaldehyde can cause hepatotoxicity and induce liver tumors in rats; however, the underlying mechanism is unclear. Liver cells contain many mitochondria, which serve to maintain energy levels in the body. We hypothesized that the energy metabolism disorder caused by mitochondrial dysfunction is an important cause of liver injury in rats exposed to crotonaldehyde. To test this, we randomly divided 40 male Wistar rats into four groups, and provided crotonaldehyde at 0, 2.5, 4.5, and 8.5 mg/kg for 90 days by intragastric administration. The results showed that crotonaldehyde exposure caused damage to liver mitochondrial structure, reduced electron-transport chain activity and ATP levels, and interfered with mitochondrial DNA transcription. In response to increased crotonaldehyde exposure, rats exhibited increased reactive oxygen species levels, decreased superoxide dismutase and glutathione activity, and activation of the caspase-mediated apoptosis pathway, as well as elevated levels of alanine aminotransferase, aspartate aminotransferase, total bilirubin, and histopathological damage. Our findings, together with those of previous reports, should help elucidate the underlying mechanism of crotonaldehyde-induced mitochondrial dysfunction and energy metabolism disorder, and provide an important direction for the prevention and clinical intervention of liver diseases caused by crotonaldehyde and aldehydes with similar structures.

Acute and chronic vascular effects of inhaled crotonaldehyde in mice: Role of TRPA1

Although crotonaldehyde (CR) is an abundant α,β-unsaturated aldehyde in mainstream cigarette smoke (MCS), the cardiovascular toxicity of inhaled CR is largely unexplored. Thus, male C57BL/6 J mice were exposed acutely (1 h, 6 h, and 4d) and chronically (12 weeks) to CR (at levels relevant to MCS; 1 and 3 ppm), and cardiovascular and systemic outcomes were measured in vivo and in vitro. Diastolic blood pressure was decreased (hypotension) by both acute and chronic CR exposure. Vascular toxicity of inhaled CR was quantified in isolated aorta in response to agonists of contraction (phenylephrine, PE) and relaxation (acetylcholine, ACh; sodium nitroprusside, SNP). Although no change in contractility was observed, ACh-induced relaxations were augmented after both acute and chronic CR exposures whereas SNP-induced relaxation was enhanced only following 3 ppm CR exposure. Because CR is a known agonist of the transient receptor potential ankyrin 1 (TRPA1) channel, male TRPA1-null mice were exposed to air or CR (4d, 1 ppm) and aortic function assessed in vitro. CR exposure had no effect on TRPA1-null aortic function indicating a role of TRPA1 in CR effects in C57BL/6 J mice. Notably, CR exposure (4d, 1 ppm) had no effect on aortic function in female C57BL/6 J mice. This study shows that CR inhalation exposure induces real-time and persistent vascular changes that promote hypotension-a known risk factor for stroke. Because of continued widespread exposures of humans to combustion-derived CR (environmental and tobacco products), CR may be an important cardiovascular disease risk factor.

Crotonaldehyde-induced vascular relaxation and toxicity: Role of endothelium and transient receptor potential ankyrin-1 (TRPA1)

INTRODUCTION

Crotonaldehyde (CR) is an electrophilic α,β-unsaturated aldehyde present in foods and beverages and is a minor metabolite of 1,3-butadiene. CR is a product of incomplete combustion, and is at high levels in smoke of cigarettes and structural fires. Exposure to CR has been linked to cardiopulmonary toxicity and cardiovascular disease.

OBJECTIVE

The purpose of this study was to examine the direct effects of CR in murine blood vessels (aorta and superior mesenteric artery, SMA) using an in vitro system.

METHODS AND RESULTS

CR induced concentration-dependent (1-300 μM) relaxations (75-80%) in phenylephrine (PE) precontracted aorta and SMA. Because the SMA was 20× more sensitive to CR than aorta (SMA EC50 3.8 ± 0.5 μM; aorta EC50 76.0 ± 2.0 μM), mechanisms of CR relaxation were studied in SMA. The CR-induced relaxation at low concentrations (1-30 μM) was inhibited by: 1) mechanically-impaired endothelium; 2) Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME); 3) guanylyl cyclase (GC) inhibitor (ODQ); 4) transient receptor potential ankyrin-1 (TRPA1) antagonist (A967079); and, 5) by non-vasoactive level of nicotine (1 μM). Similarly, a TRPA1 agonist, allyl isothiocyanate (AITC; mustard oil), stimulated SMA relaxation dependent on TRPA1, endothelium, NO, and GC. Consistent with these mechanisms, TRPA1 was present in the SMA endothelium. CR, at higher concentrations (100-300 μM), induced tension oscillations (spasms) and irreversibly impaired contractility (a vasotoxic effect enhanced by impaired endothelium).

CONCLUSIONS

CR relaxation depends on a functional endothelium and TRPA1, whereas vasotoxicity is enhanced by endothelium dysfunction. Thus, CR is both vasoactive and vasotoxic along a concentration continuum.