Modeling vascular inflammation and atherogenicity after inhalation of ambient levels of ozone: exploratory lessons from transcriptomics

Enhancing the health benefits of air quality improvement: a comparative study across diverse scenarios

In many studies, linear methods were used to calculate health benefits of air quality improvement, but the relationship between air pollutants and diseases may be complex and nonlinear. In addition, previous studies using reference number as average number of diseases may overestimate the health benefits. Therefore, the nonlinear model estimation and resetting of the reference number were very important. Hospital admission data for coronary heart disease (CHD), meteorological data, and air pollutant data of Zibo City from 2015 to 2019 were collected. The generalized additive model (GAM) was used to explore the association between air pollutants and hospital admission for CHD, and to evaluate the effects on health benefits under different reference number settings. A total of 21,105 hospitalized cases for CHD were reported in Zibo during the study period. The results of the GAM showed there was a log-linear exposure-response relationship between O3 and hospital admissions for CHD, with RR (relative risk) of 1.0143 (95% CI: 1.0047 ~ 1.0239). There were log-nonlinear exposure-response relationships between PM10, PM2.5, SO2, and hospital admissions for CHD. With the increase of pollutants concentrations, the risk for hospital admission showed a trend of increasing first and then decreasing. Compared with the average hospital admissions as the reference number, health benefits calculated by hospital admissions predicted by the GAM model yielded lower. Using the World Health Organization air quality guidelines as reference, attributable fractions of O3, PM10, and PM2.5 were 1.97% (95% CI: 0.63 ~ 3.40%), 11.82% (95% CI: 8.60 ~ 15.24%), and 11.82% (95% CI: 8.79 ~ 15.04%), respectively. When quantifying health benefits brought by improving air quality, corresponding calculation methods should first be determined according to the exposure-response relationships between air pollutants and outcomes. Then, applying the average hospital admissions as reference number may overestimate health benefits resulting from improved air quality.

Acute and Repeated Ozone Exposures Differentially Affect Circadian Clock Gene Expression in Mice

Circadian rhythms have an established role in regulating physiological processes, such as inflammation, immunity, and metabolism. Ozone, a common environmental pollutant with strong oxidative potential, is implicated in lung inflammation/injury in asthmatics. However, whether O3 exposure affects the expression of circadian clock genes in the lungs is not known. In this study, changes in the expression of core clock genes are analyzed in the lungs of adult female and male mice exposed to filtered air (FA) or O3 using qRT-PCR. The findings are confirmed using an existing RNA-sequencing dataset from repeated FA- and O3 -exposed mouse lungs and validated by qRT-PCR. Acute O3 exposure significantly alters the expression of clock genes in the lungs of females (Per1, Cry1, and Rora) and males (Per1). RNA-seq data revealing sex-based differences in clock gene expression in the airway of males (decreased Nr1d1/Rev-erbα) and females (increased Skp1), parenchyma of females and males (decreased Nr1d1 and Fbxl3 and increased Bhlhe40 and Skp1), and alveolar macrophages of males (decreased Arntl/Bmal1, Per1, Per2, Prkab1, and Prkab2) and females (increased Cry2, Per1, Per2, Csnk1d, Csnk1e, Prkab2, and Fbxl3). These findings suggest that lung inflammation caused by O3 exposure affects clock genes which may regulate key signaling pathways.

Adjunctive therapies for in vitro carious lesions: Antimicrobial activity, activation of dentin metalloproteinases and effects on dental pulp cells

BACKGROUND

Adjunctive therapies used before dental restorative procedures may encourage carious tissue removal. Beyond promising antimicrobial properties, treatments could positively modulate the dentin-pulp complex while not interfering with restoration survival. Herein, we evaluated a set of substances and their effects on carious lesions and the underlying dentin or pulp cells.

METHODS

Artificial caries lesions were developed in bovine teeth cavities immersed in Streptococcus mutans and Lactobacillus casei co-cultures. The cavities were treated according to the following groups: Phosphate Buffer Saline (PBS), Chlorhexidine (CHX), Papacárie® (Papain gel), Ozone (O₃), and antimicrobial Photodynamic Therapy (aPDT). After treatments, samples were cultivated to count isolated microbial colonies. The zymography assay evaluated the activity of dentin metalloproteinases (MMP-2 and MMP-9). Cell viability was indirectly assessed on human dental pulp cells after 24, 72, or 120 h, whereas the odontodifferentiation potential was evaluated after ten days of cell culture.

RESULTS

CHX and aPDT led to around 1 log bacterial load reduction. PBS, CHX, and aPDT showed the eventual expression of MMP-2 and MMP-9. Cell viability was reduced (< 30%) after 120 h for all groups compared to the control. CHX, O3, and aPDT induced greater odontodifferentiation (≈ 20% higher) than PBS and papain gel.

CONCLUSION

Adjunctive therapies presented little or no biological significance in reducing bacterial load in artificial carious lesions. Although the activation of endogenous metalloproteinases may represent a possible concern for adhesive restorations, some of these treatments may have a positive role in dental pulp tissue repair.

Particulate matter and ozone might trigger deaths from chronic ischemic heart disease

AIMS

To study the association between short-term exposure to air pollutants and mortality of Chronic Ischemic Heart Disease (CIHD).

METHODS

Using a case-crossover design, we investigated 148,443 CIHD deaths from 2015 to 2020 in Jiangsu Province, China. Exposure to six ambient pollutants, including PM₁₀, PM_2.5, NO₂, CO, SO₂, and O_3, was assessed by extracting daily concentrations from validated 10 km × 10 km pollutant grids at each subject's residential address. A conditional logistic regression approach was used to explore the exposure-response relationship with adjustment for temperature and relative humidity. We calculated the Population Attributable Fractions (PAFs) and the attributable deaths number of CIHD.

RESULTS

An increase of 10 μg/m³ in PM₁₀ and PM_2.5 exposure was associated with a 1.16% (95% CI: 0.85-1.48%) and 1.80% (1.36-2.24%) increase in CIHD mortality, respectively. A threshold value of 123 µg/m³ was identified for the association between O₃ exposure and CIHD mortality. Controlling for PM_2.5, each increase of 10 µg/m³ in O₃ (>threshold) was statistically significantly associated with a 0.94% (0.19-1.71%) increase in CIHD mortality, however there was no association between NO₂, SO₂, CO exposure and CIHD mortality. Reducing PM_2.5, PM₁₀ and O₃ to the WHO air quality guidelines would prevent 6.16% (95% CI: 4.70-7.58%), 4.30% (3.18-5.43%) and 1.29% (0.48-4.20%) of CIHD deaths, respectively. During the warm season, mortality and PAFs of CIHD associated with PM_2.5, PM₁₀, and O₃ were significantly higher.

CONCLUSIONS

Short-term exposure to ambient PM_2.5, PM_10, and O₃ might trigger deaths from CIHD. These findings indicate that the premature deaths of CIHD patients can be alleviated by reducing exposure to polluted air.

'Omics in environmental epidemiological studies of chemical exposures: A systematic evidence map

BACKGROUND

Systematic evidence maps are increasingly used to develop chemical risk assessments. These maps can provide an overview of available studies and relevant study information to be used for various research objectives and applications. Environmental epidemiological studies that examine the impact of chemical exposures on various 'omic profiles in human populations provide relevant mechanistic information and can be used for benchmark dose modeling to derive potential human health reference values.

OBJECTIVES

To create a systematic evidence map of environmental epidemiological studies examining environmental contaminant exposures with 'omics in order to characterize the extent of available studies for future research needs.

METHODS

Systematic review methods were used to search and screen the literature and included the use of machine learning methods to facilitate screening studies. The Populations, Exposures, Comparators and Outcomes (PECO) criteria were developed to identify and screen relevant studies. Studies that met the PECO criteria after full-text review were summarized with information such as study population, study design, sample size, exposure measurement, and 'omics analysis.

RESULTS

Over 10,000 studies were identified from scientific databases. Screening processes were used to identify 84 studies considered PECO-relevant after full-text review. Various contaminants (e.g. phthalate, benzene, arsenic, etc.) were investigated in epidemiological studies that used one or more of the four 'omics of interest: epigenomics, transcriptomics, proteomics, and metabolomics . The epidemiological study designs that were used to explore single or integrated 'omic research questions with contaminant exposures were cohort studies, controlled trials, cross-sectional, and case-control studies. An interactive web-based systematic evidence map was created to display more study-related information.

CONCLUSIONS

This systematic evidence map is a novel tool to visually characterize the available environmental epidemiological studies investigating contaminants and biological effects using 'omics technology and serves as a resource for investigators and allows for a range of applications in chemical research and risk assessment needs.

Ozone Exposure Induces Metabolic Disorders and NAD+ Depletion Through PARP1 Activation in Spinal Cord Neurons

Background and Objective: Ozone therapy has shown therapeutic efficacy in different disorders particularly low back pain (LBP). However, ozone therapy has been associated with toxic effects on the respiratory, endocrine, cardiovascular systems as well as nervous system because of its strong oxidizing capacity. Recent studies have reported possible associations between ozone exposure and metabolic disorders, but the findings are controversial and little is known on the mechanisms of action. This study aims to investigate the cytotoxic effects of ozone exposure and possible mechanism of action in the animal model.

Methods: Wistar neonate rats with the age of 24 h after birth were sacrificed by cervical dislocation under general anesthesia, then immersed in 75% alcohol and iodophor for 5 min, respectively. The spinal cord was isolated and cut to samples of ~1 mm³ and prepared for further experiments. The spinal cord neurons (SCNs) were exposed to ozone at different concentrations and then cultured in 96-well plates with glass bottom for 7 days. The cell viability, ATP levels and the NAD+ concentration were determined and compared between the different experimental groups and the control group.

Results: Analyses of the data by non-targeted liquid chromatography-mass spectrometry (LC-MS) analysis determined the metabolic disorder in SCNs following the ozone exposure. Moreover, our assessments showed that ozone exposure resulted in DNA damage, poly (ADP)-ribose polymerase-1 (PARP1) excessive activation, nicotinamide adenine dinucleotide (NAD+) depletion and decrease of ATP level in SCNs. The PARP1 inhibitor can inhibit the cytotoxic effect of ozone to SCNs without inhibiting the activation of AMP-activated protein kinase (AMPK). Our findings revealed that the cytotoxic effects of ozone to SCNs might be mediated by excessive PARP1 activation and subsequent NAD+ depletion. Moreover, using PARP1 inhibitor can protect SCNs from cytotoxic effects of ozone by preventing NAD+ depletion during ozone exposure.

Conclusion: Ozone exposure seems to induce metabolic disorders and NAD+ depletion through excessive PARP1 activation in SCNs.

Nanoparticle exposure driven circulating bioactive peptidome causes systemic inflammation and vascular dysfunction

Background

The mechanisms driving systemic effects consequent pulmonary nanoparticle exposure remain unclear. Recent work has established the existence of an indirect process by which factors released from the lung into the circulation promote systemic inflammation and cellular dysfunction, particularly on the vasculature. However, the composition of circulating contributing factors and how they are produced remains unknown. Evidence suggests matrix protease involvement; thus, here we used a well-characterized multi-walled carbon nanotube (MWCNT) oropharyngeal aspiration model with known vascular effects to assess the distinct contribution of nanoparticle-induced peptide fragments in driving systemic pathobiology.

Results

Data-independent mass spectrometry enabled the unbiased quantitative characterization of 841 significant MWCNT-responses within an enriched peptide fraction, with 567 of these factors demonstrating significant correlation across animal-paired bronchoalveolar lavage and serum biofluids. A database search curated for known matrix protease substrates and predicted signaling motifs enabled identification of 73 MWCNT-responsive peptides, which were significantly associated with an abnormal cardiovascular phenotype, extracellular matrix organization, immune-inflammatory processes, cell receptor signaling, and a MWCNT-altered serum exosome population. Production of a diverse peptidomic response was supported by a wide number of upregulated matrix and lysosomal proteases in the lung after MWCNT exposure. The peptide fraction was then found bioactive, producing endothelial cell inflammation and vascular dysfunction ex vivo akin to that induced with whole serum. Results implicate receptor ligand functionality in driving systemic effects, exemplified by an identified 59-mer thrombospondin fragment, replete with CD36 modulatory motifs, that when synthesized produced an anti-angiogenic response in vitro matching that of the peptide fraction. Other identified peptides point to integrin ligand functionality and more broadly to a diversity of receptor-mediated bioactivity induced by the peptidomic response to nanoparticle exposure.

Conclusion

The present study demonstrates that pulmonary-sequestered nanoparticles, such as multi-walled carbon nanotubes, acutely upregulate a diverse profile of matrix proteases, and induce a complex peptidomic response across lung and blood compartments. The serum peptide fraction, having cell-surface receptor ligand properties, conveys peripheral bioactivity in promoting endothelial cell inflammation, vasodilatory dysfunction and inhibiting angiogenesis. Results here establish peptide fragments as indirect, non-cytokine mediators and putative biomarkers of systemic health outcomes from nanoparticle exposure.