The impact of benzo[a]pyrene on murine allergic airway inflammation via epigenetic remodeling

Co-exposure effects of urinary polycyclic aromatic hydrocarbons and metals on lung function: mediating role of systematic inflammation

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) and metals were associated with decreased lung function, but co-exposure effects and underlying mechanism remained unknown.

METHODS

Among 1,123 adults from National Health and Nutrition Examination Survey 2011-2012, 10 urinary PAHs, 11 urinary metals, and peripheral white blood cell (WBC) count were determined, and 5 lung function indices were measured. Least absolute shrinkage and selection operator, Bayesian kernel machine regression, and quantile-based g-computation were used to estimate co-exposure effects on lung function. Mediation analysis was used to explore mediating role of WBC.

RESULTS

These models demonstrated that PAHs and metals were significantly associated with lung function impairment. Bayesian kernel machine regression models showed that comparing to all chemicals fixed at median level, forced expiratory volume in 1 s (FEV1)/forced vital capacity, peak expiratory flow, and forced expiratory flow between 25 and 75% decreased by 1.31% (95% CI: 0.72%, 1.91%), 231.62 (43.45, 419.78) mL/s, and 131.64 (37.54, 225.74) mL/s respectively, when all chemicals were at 75th percentile. In the quantile-based g-computation, each quartile increase in mixture was associated with 104.35 (95% CI: 40.67, 168.02) mL, 1.16% (2.11%, 22.40%), 294.90 (78.37, 511.43) mL/s, 168.44 (41.66, 295.22) mL/s decrease in the FEV1, FEV1/forced vital capacity, peak expiratory flow, and forced expiratory flow between 25% and 75%, respectively. 2-Hydroxyphenanthrene, 3-Hydroxyfluorene, and cadmium were leading contributors to the above associations. WBC mediated 8.22%-23.90% of association between PAHs and lung function.

CONCLUSIONS

Co-exposure of PAHs and metals impairs lung function, and WBC could partially mediate this relationship. Our findings elucidate co-exposure effects of environmental mixtures on respiratory health and underlying mechanisms, suggesting that focusing on highly prioritized toxicants would effectively attenuate adverse effects.

Histone H3K36me3 mediates the genomic instability of Benzo[a]pyrene in human bronchial epithelial cells

Histone modifications maintain genomic stability and orchestrate gene expression at the chromatin level. Benzo [a]pyrene (BaP) is the ubiquitous carcinogen widely spread in the environment, but the role and regulatory mechanism of histone modification in its toxic effects remain largely undefined. In this study, we found a dose-dependent reduction of histone H3 methylations at lysine4, lysine9, lysine27, lysine36 in HBE cells treated with BaP. We observed that inhibiting H3K27 and H3K36 methylation impaired cell proliferation, whereas the loss of H3K4, H3K9, H3K27, and H3K36 methylation led to increased genomic instability and delayed DNA repair. H3K36 mutation at both H3.1 and H3.3 exhibited the most significant impacts. In addition, we found that the expression of SET domain containing 2 (SETD2), the unique methyltransferase catalyzed H3K36me3, was downregulated by BaP dose-dependently in vitro and in vivo. Knockdown of SETD2 aggravated DNA damage of BaP exposure, which was consistent with the effects of H3K36 mutation. With the aid of chromatin immunoprecipitation (ChIP) -seq and RNA-seq, we found that H3K36me3 was responsible for transcriptional regulation of genes involved in pathways related to cell survival, lung cancer, metabolism and inflammation. The enhanced enrichment of H3K36me3 in genes (CYP1A1, ALDH1A3, ACOXL, WNT5A, WNT7A, RUNX2, IL1R2) was positively correlated with their expression levels, while the reduction of H3K36me3 distribution in genes (PPARGC1A, PDE4D, GAS1, RNF19A, KSR1) were in accordance with the downregulation of gene expression. Taken together, our findings emphasize the critical roles and mechanisms of histone lysine methylation in mediating cellular homeostasis during BaP exposure.

Integrating GWAS and proteome data to identify novel drug targets for MU

Mouth ulcers have been associated with numerous loci in genome wide association studies (GWAS). Nonetheless, it remains unclear what mechanisms are involved in the pathogenesis of mouth ulcers at these loci, as well as what the most effective ulcer drugs are. Thus, we aimed to screen hub genes responsible for mouth ulcer pathogenesis. We conducted an imputed/in-silico proteome-wide association study to discover candidate genes that impact the development of mouth ulcers and affect the expression and concentration of associated proteins in the bloodstream. The integrative analysis revealed that 35 genes play a significant role in the development of mouth ulcers, both in terms of their protein and transcriptional levels. Following this analysis, the researchers identified 6 key genes, namely BTN3A3, IL12B, BPI, FAM213A, PLXNB2, and IL22RA2, which were related to the onset of mouth ulcers. By combining with multidimensional data, six genes were found to correlate with mouth ulcer pathogenesis, which can be useful for further biological and therapeutic research.

Sulfur dioxide-enhanced asthma susceptibility is involved with inhibition of bitter taste transduction in mouse lung

Sulfur dioxide (SO₂) may induce asthma-like symptoms or worsen existing asthma, but the underlying mechanism is still unclear. In this study, the relationship between SO₂ exposure, asthma development, and bitter taste transduction was analyzed using ovalbumin (OVA)-induced and SO₂-aggravated asthma models. The results showed that twenty-seven and twelve bitter taste receptors (Tas2rs) were detectable in mouse trachea and lung, respectively, and that all of them were nearly down-regulated in OVA-induced BALB/c and C57BL/6 asthmatic mice. SO₂ exposure alone did not trigger a distinct asthma-like phenotype, but the combination of SO₂ and OVA allergen caused more severe asthma symptoms in mice including enhanced inflammatory cells infiltration, thickened airway walls, increased mucus secretion, and elevated expression of proinflammatory and Th2 cytokines (TNF-α, IL-4, IL-5, IL-13). Furthermore, SO₂ enhanced the transcriptional repression of Tas2rs in OVA-induced asthmatic mice. These results indicated that the occurrence of mice asthma was correlated with the inhibition of bitter taste transduction, and more severe airway inflammation and injury were accompanied with an enhanced inhibition of bitter taste transduction. Our findings suggest that SO₂ inhalation may amplify Th2 inflammatory responses in the lung of asthmatic mice by inhibiting bitter taste transduction, and thereby exacerbate asthma symptoms.

Gestational exposure to phenanthrene induces follicular atresia and endocrine dyscrasia in F1 adult female

Epidemiological investigations and animal studies demonstrate a significantly positive relationship between polycyclic aromatic hydrocarbons (PAHs) exposure and reproductive disorders. However, few researches are focused on the reproductive toxicity of low-molecular-weight PAHs (number of benzene ring ≤ 3) which occupy a large part of PAHs. Phenanthrene (Phe), a typical low-molecular-weight PAH, is one of the most abundant PAHs detected in foods. In the present study, oral treatment with Phe at a human exposure related level during gestation (60 μg/kg body weight every three days, six times in total) induced reproductive disorders in F1 adult female mice: the number of antral follicles (an immature stage of follicular development) were significantly increased, while the maturation of oocytes was inhibited and aggravated follicular atresia was observed; the serum levels of luteinizing hormone (LH), testosterone and estradiol were significantly reduced; the receptor of follicle-stimulating hormone (FSHR) and aromatase in the ovary were significantly upregulated; transcriptome analysis demonstrated that the phosphatidylinositol 3-kinase and protein kinase B (PI3K/Akt) signal pathway was upregulated, and the calcium signal pathway was disturbed, which probably accounts for the exacerbated atresia of the growing follicles and the excessive consumption of follicles. The reproductive toxicity of low-molecular-weight PAHs could not be neglected.