DNA Methylome Analysis of Saturated Aliphatic Aldehydes in Pulmonary Toxicity

Chemical sensors for imaging total cellular aliphatic aldehydes in live cells

Aliphatic aldehydes are reactive electrophilic carbonyls that cross-link with DNA and proteins leading to cellular toxicity and disease pathogenesis. This toxicity is due to the cooperative effect of multiple aldehydes via a common mechanism. Therefore, live-cell imaging of total aliphatic aldehydes, small-to-long chain (C1-C10), is highly desired to decipher their physiological and pathological functions. However, sensors for imaging total cellular aliphatic aldehydes are currently lacking despite their high concentrations (∼80 to >500 μM) inside cells. Herein, we report chemical sensors that generate a benzimidazole moiety upon reaction with aliphatic aldehydes of different chain lengths (C1-C10), resulting in turn-on fluorescence. These sensors exhibit high quantum yields, high dynamic range, and enable the quantification of changes in both the exogenous administration of aldehydes and endogenous real-time formation of aliphatic aldehydes in live mammalian cells. This tool has great potential to transform aldehyde research by illuminating cellular metabolites that have remained elusive in living systems.

Organoiridium Complexes Enhance Cellular Defense Against Reactive Aldehydes Species

Although reactive aldehyde species (RASP) are associated with the pathogenesis of many major diseases, there are currently no clinically approved treatments for RASP overload. Conventional aldehyde detox agents are stoichiometric reactants that get consumed upon reacting with their biological targets, which limits their therapeutic efficiency. To achieve longer-lasting detoxification effects, small-molecule intracellular metal catalysts (SIMCats) were used to protect cells by converting RASP into non-toxic alcohols. It was shown that SIMCats were significantly more effective in lowering cell death from the treatment with 4-hydroxynon-2-enal than aldehyde scavengers over a 72 h period. Studies revealed that SIMCats reduced the aldehyde accumulation in cells exposed to the known RASP inducer arsenic trioxide. This work demonstrates that SIMCats offer unique benefits over stochiometric agents, potentially providing new ways to combat diseases with greater selectivity and efficiency than existing approaches.

Out of Thin Air? Catalytic Oxidation of Trace Aqueous Aldehydes with Ambient Dissolved Oxygen

Water reuse is expanding due to increased water scarcity. Water reuse facilities treat wastewater effluent to a very high purity level, typically resulting in a product water that is essentially deionized water, often containing less than 100 μg/L organic carbon. However, recent research has found that low-molecular-weight aldehydes, which are toxic electrophiles, comprise a significant fraction of the final organic carbon pool in recycled wastewater in certain treatment configurations. In this manuscript, we demonstrate oxidation of trace aqueous aldehydes to their corresponding acids using a heterogeneous catalyst (5% Pt on C), with ambient dissolved oxygen serving as the terminal electron acceptor. Mass balances are essentially quantitative across a range of aldehydes, and pseudo-first-order reaction kinetics are observed in batch reactors, with k_obs varying from 0.6 h^-1 for acetaldehyde to 4.6 h^-1 for hexanal, while they are low for unsaturated aldehydes. Through kinetic and isotopic labeling experiments, we demonstrate that while oxygen is essential for the reaction to proceed, it is not involved in the rate-limiting step, and the reaction appears to proceed primarily through a base-promoted β-hydride elimination mechanism from the hydrated gem-diol form of the corresponding aldehyde. This is the first report we are aware of that demonstrates useful abiotic oxidation of a trace organic contaminant using dissolved oxygen.

Evidence-Based Challenges to the Continued Recommendation and Use of Peroxidatively-Susceptible Polyunsaturated Fatty Acid-Rich Culinary Oils for High-Temperature Frying Practises: Experimental Revelations Focused on Toxic Aldehydic Lipid Oxidation Products

In this manuscript, a series of research reports focused on dietary lipid oxidation products (LOPs), their toxicities and adverse health effects are critically reviewed in order to present a challenge to the mindset supporting, or strongly supporting, the notion that polyunsaturated fatty acid-laden frying oils are "safe" to use for high-temperature frying practises. The generation, physiological fates, and toxicities of less commonly known or documented LOPs, such as epoxy-fatty acids, are also considered. Primarily, an introduction to the sequential autocatalytic peroxidative degradation of unsaturated fatty acids (UFAs) occurring during frying episodes is described, as are the potential adverse health effects posed by the dietary consumption of aldehydic and other LOP toxins formed. In continuance, statistics on the dietary consumption of fried foods by humans are reviewed, with a special consideration of French fries. Subsequently, estimates of human dietary aldehyde intake are critically explored, which unfortunately are limited to acrolein and other lower homologues such as acetaldehyde and formaldehyde. However, a full update on estimates of quantities derived from fried food sources is provided here. Further items reviewed include the biochemical reactivities, metabolism and volatilities of aldehydic LOPs (the latter of which is of critical importance regarding the adverse health effects mediated by the inhalation of cooking/frying oil fumes); their toxicological actions, including sections focussed on governmental health authority tolerable daily intakes, delivery methods and routes employed for assessing such effects in animal model systems, along with problems encountered with the Cramer classification of such toxins. The mutagenicities, genotoxicities, and carcinogenic potential of aldehydes are then reviewed in some detail, and following this the physiological concentrations of aldehydes and their likely dietary sources are considered. Finally, conclusions from this study are drawn, with special reference to requirements for (1) the establishment of tolerable daily intake (TDI) values for a much wider range of aldehydic LOPs, and (2) the performance of future nutritional and epidemiological trials to explore associations between their dietary intake and the incidence and severity of non-communicable chronic diseases (NCDs).

Genome-wide DNA methylation analysis of pulmonary function in middle and old-aged Chinese monozygotic twins

BACKGROUND

Previous studies have determined the epigenetic association between DNA methylation and pulmonary function among various ethnics, whereas this association is largely unknown in Chinese adults. Thus, we aimed to explore epigenetic relationships between genome-wide DNA methylation levels and pulmonary function among middle-aged Chinese monozygotic twins.

METHODS

The monozygotic twin sample was drawn from the Qingdao Twin Registry. Pulmonary function was measured by three parameters including forced expiratory volume the first second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio. Linear mixed effect model was used to regress the methylation level of CpG sites on pulmonary function. After that, we applied Genomic Regions Enrichment of Annotations Tool (GREAT) to predict the genomic regions enrichment, and used comb-p python library to detect differentially methylated regions (DMRs). Gene expression analysis was conducted to validate the results of differentially methylated analyses.

RESULTS

We identified 112 CpG sites with the level of P < 1 × 10^-4 which were annotated to 40 genes. We identified 12 common enriched pathways of three pulmonary function parameters. We detected 39 DMRs located at 23 genes, of which PRDM1 was related to decreased pulmonary function, and MPL, LTB4R2, and EPHB3 were related to increased pulmonary function. The gene expression analyses validated DIP2C, ASB2, SLC6A5, and GAS6 related to decreased pulmonary function.

CONCLUSION

Our DNA methylation sequencing analysis on identical twins provides new references for the epigenetic regulation on pulmonary function. Several CpG sites, genes, biological pathways and DMRs are considered as possible crucial to pulmonary function.

Exposure characteristics and risk assessment of VOCs from Chinese residential cooking

In comparison with various restaurant cuisines, common cooking methods are more represented in residential cooking. Rather than the exhaust pipe or the ambient environment in the cooking room, the respiration zone better reflects the health risks for operators. In this study, the concentrations of total volatile organic compound (TVOC) released from six typical cooking methods were monitored online in the respiratory zone, and the VOCs were analysed by GC-MS. The results demonstrated that the intensities of exposure to TVOC for the different cooking methods decreased as follows: stir-frying (3.809 mg/m³) > quick-frying (2.724 mg/m³) > deep-frying (2.465 mg/m³) > boiling (1.161 mg/m³)≈stewing (1.149 mg/m³) > limit in China (0.600 mg/m³) > steaming (0.440 mg/m³). The intense ventilation mode of the ventilator reduced exposure to TVOC by 45-63% relative to the medium mode. Eleven types of VOCs (approximately 200 compounds) were found in Chinese residential cooking fumes, and the predominant contaminants were aldehydes, followed by alkanes, unsaturated aldehydes, alcohols and alkenes. The mass percentage of aromatic hydrocarbons in all VOCs emitted from Chinese residential cooking was only 1%, while the value was 17-48% for commercial restaurants. The results of a health risk assessment revealed that the total potential carcinogenic risk level for VOCs released by six residential cooking methods decreased as follows: deep-frying (5.75) > stir-frying (3.95) > quick-frying (2.94) > stewing (1.99) > boiling (1.73) > steaming (1.48). Chinese residential cooking, and especially deep frying, has potential health impacts for the operator.

Epimutational effects of electronic cigarettes

Electronic cigarettes (e-cigarettes), since they do not require tobacco combustion, have traditionally been considered less harmful than conventional cigarettes (c-cigarettes). In recent years, however, researchers have found many toxic compounds in the aerosols of e-cigarettes, and numerous studies have shown that e-cigarettes can adversely affect the human epigenome. In this review, we provide an update on recent findings regarding epigenetic outcomes of e-cigarette aerosols. Moreover, we discussed the effects of several typical e-cigarette ingredients (nicotine, tobacco-specific nitrosamines, volatile organic compounds, carbonyl compounds, and toxic metals) on DNA methylation, histone modifications, and noncoding RNA expression. These epigenetic effects could explain some of the diseases caused by e-cigarettes. It also reminds the public that like c-cigarettes, inhaling e-cigarette aerosols could also be accompanied with potential epigenotoxicity on the human body.

DNA methylome signatures as epigenetic biomarkers of hexanal associated with lung toxicity

Background

Numerous studies have investigated the relationship of environmental exposure, epigenetic effects, and human diseases. These linkages may contribute to the potential toxicity mechanisms of environmental chemicals. Here, we investigated the epigenetic pulmonary response of hexanal, a major indoor irritant, following inhalation exposure in F-344 rats.

Methods

Based on DNA methylation profiling in gene promoter regions, we identified hexanal-characterized methylated sites and target genes using an unpaired t-test with a fold-change cutoff of ≥ 3.0 and a p-value < 0.05. We also conducted an integrated analysis of DNA methylation and mRNA expression data to identify core anti-correlated target genes of hexanal exposure. To further investigate the potential key biological processes and pathways of core DNA methylated target genes, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis were performed.

Results

Thirty-six dose-dependent methylated genes and anti-correlated target genes of DNA methylation and mRNA in lung tissue of hexanal exposed F-344 rats were identified. These genes were involved in diverse biological processes such as neuroactive ligand-receptor interaction, protein kinase cascade, and intracellular signaling cascade associated with pulmonary toxicity. These results suggest that novel DNA methylation-based epigenetic biomarkers of exposure to hexanal and elucidate the potential pulmonary toxicological mechanisms of action of hexanal.

Utilization of metal-organic frameworks for the adsorptive removal of an aliphatic aldehyde mixture in the gas phase

Considerable efforts have been undertaken in the domain of air quality management for the removal of hazardous volatile organic compounds, particularly carbonyl compounds (CCs). In this study, the competitive sorptive removal of six CCs (namely, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde) was assessed using selected metal-organic frameworks (MOFs: MOF-5, MOF-199, UiO-66, and UiO-66-NH₂) and inexpensive commercial activated carbon as a reference sorbent. The sorption experiments were conducted using a mixture of the six CCs (formaldehyde and acetaldehyde at ∼1 Pa and propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde at ∼0.2 Pa) together with 15 Pa water and 2.6 Pa methanol in 1 bar nitrogen. For all of the carbonyl compounds other than formaldehyde, MOF-199 showed the best 10% breakthrough performance ranging from 34 L g^-1 and 0.14 mol kg^-1 Pa^-1 for acetaldehyde to 1870 L g^-1 and 7.6 mol kg^-1 Pa^-1 for isovaleraldehyde. Among all the sorbents tested, UiO-66-NH₂ exhibited the best 10% breakthrough performance metrics towards the lightest formaldehyde which remains to be one of the most difficult targets for sorptive removal (breakthrough volume: 285 L g^-1 and partition coefficient: 1.1 mol kg^-1 Pa^-1). Theoretical density functional theory (DFT)-based computations were also conducted to provide better insights into the adsorbate-adsorbent interactions. Accordingly, the magnitude of adsorption energy increased with an increase in the CC molar mass due to an enhancement in the synergetic interaction between C[double bond, length as m-dash]O groups (in adsorbate molecules) and the MOF active centers (open metallic centers and/or NH₂ functionality) as the adsorbent. Such interactions were observed to result in strong distortion of MOF structures. In contrast, weak van der Waals attraction between the hydrocarbon "tail" of CC molecules and MOF linkers were seen to play a stabilizing role for the sorbent structure. The presence of the NH₂ group in the MOF structure was suspected to play a key role in capturing lighter CCs, while such an effect was less prominent for heavier CCs. Overall, the results of this study provided a basis for the establishment of an effective strategy to enhance the sorption capacity of MOFs against diverse carbonyl species.

Potential Adverse Public Health Effects Afforded by the Ingestion of Dietary Lipid Oxidation Product Toxins: Significance of Fried Food Sources

Exposure of polyunsaturated fatty acid (PUFA)-rich culinary oils (COs) to high temperature frying practices generates high concentrations of cytotoxic and genotoxic lipid oxidation products (LOPs) via oxygen-fueled, recycling peroxidative bursts. These toxins, including aldehydes and epoxy-fatty acids, readily penetrate into fried foods and hence are available for human consumption; therefore, they may pose substantial health hazards. Although previous reports have claimed health benefits offered by the use of PUFA-laden COs for frying purposes, these may be erroneous in view of their failure to consider the negating adverse public health threats presented by food-transferable LOPs therein. When absorbed from the gastrointestinal (GI) system into the systemic circulation, such LOPs may significantly contribute to enhanced risks of chronic non-communicable diseases (NCDs), e.g. cancer, along with cardiovascular and neurological diseases. Herein, we provide a comprehensive rationale relating to the public health threats posed by the dietary ingestion of LOPs in fried foods. We begin with an introduction to sequential lipid peroxidation processes, describing the noxious effects of LOP toxins generated therefrom. We continue to discuss GI system interactions, the metabolism and biotransformation of primary lipid hydroperoxide LOPs and their secondary products, and the toxicological properties of these agents, prior to providing a narrative on chemically-reactive, secondary aldehydic LOPs available for human ingestion. In view of a range of previous studies focused on their deleterious health effects in animal and cellular model systems, some emphasis is placed on the physiological fate of the more prevalent and toxic α,β-unsaturated aldehydes. We conclude with a description of targeted nutritional and interventional strategies, whilst highlighting the urgent and unmet clinical need for nutritional and epidemiological trials probing relationships between the incidence of NCDs, and the frequency and estimated quantities of dietary LOP intake.

The emission characteristic of VOCs and the toxicity of BTEX from different mosquito-repellent incenses

Three types of mosquito-repellent incenses including disc, electric liquid and electric mat, were selected to investigate the emission of volatile organic compounds in the respiratory zone during the burning. VOCs were analyzed by GC-MS. Results showed that the average concentration of TVOCs released by using the disc, electric liquid and electric mat mosquito repellent incense types were 7.760 ± 4.724, 3.122 ± 0.866 and 1.192 ± 0.062 mg/m³, respectively. The TVOCs pollution level produced during the burning of different mosquito-repellent incense types was ranked in the order: disc > electric liquid > electric mat. The concentration of TVOCs produced by Q-liquid, L-liquid, Q-disc and L-disc mosquito-repellent incense types could cause discomfort to the human body. Other types of mosquito-repellent incense induced multiple synergistic effects on human response. About 230 kinds of VOCs including 14 types of VOCs, were found in the smoke of mosquito-repellent incense. The number and content of alkanes was the highest, followed by aromatic hydrocarbons and esters. The level of non-carcinogenic health risk presented by exposure to BTEX (toluene, xylene and ethylbenzene) was acceptable. The chronic daily intake of VOCs decreased with age for both males and females, with male exposure being higher than that of the female, except for children.