OBJECTIVES:To evaluate recent advances and current challenges in inhaled aerosol dosimetry research, with a focus on understanding how particles affect human health through deposited doses, and to identify key research needs for improving exposure assessment and risk evaluation. METHODS:The findings were based on discussions and presentations from the Fourth International Aerosol Dosimetry Conference held in 2024 in Irvine, California. The conference used plenary sessions to promote cross-disciplinary communication and collaboration. Topics included computational models and simulations, in vitro and in vivo aerosol exposure systems, and variability in inhaled aerosol deposition. State-of-the-art research was presented, followed by open discussions to identify knowledge gaps and future priorities. RESULTS:Significant advances were reported in computational modeling, particularly in integrating different model types to better represent all major regions of the respiratory tract. Improvements in in vitro exposure systems enhanced particle delivery, dose measurement, and applicability to human health studies. Research also highlighted the importance of the upper airways as entry routes for inhaled medications. Dose variability emerged as a critical issue across aerosol dosimetry studies. New findings showed that inhaled ultrafine particles may acquire surface coatings after deposition and can penetrate tissues, including fetal tissues. Standardization and validation of in vitro approaches were identified as essential steps for reducing reliance on animal testing and improving human risk assessment. CONCLUSION:Internal aerosol dosimetry research continues to advance through improved models, exposure systems, and mechanistic understanding of deposited particle behavior. However, addressing dose variability, standardizing alternative testing methods, and improving data sharing remain essential for advancing risk assessment and supporting more accurate evaluations of inhaled particle effects on human health.
BACKGROUND:Increased ambient temperature alongside concomitant heatwaves and wildfire smoke imperil human health. We examined whether long-term episodic exposure to wildfire smoke induced greater respiratory injury/inflammation in male rats subchronically housed at elevated temperature or consuming unhealthy, cholesterol-rich diets. Respiratory effects of wildfire eucalyptus smoke exposure (WFES; ∼7mg/m3 particulate matter) were assessed 2h and 24h post-exposure in rats housed at 22 °C (room temperature; RT) consuming normal diet (ND) and exposed to filtered air (FA) or WFES for 1h. METHODS:To determine effects of ongoing exposure, 4-5-week-old rats were subchronically housed at RT or high temperature (HT; 30-31°C) and fed ND or high-cholesterol (2%) diet (HCD). Rats were episodically exposed to FA or WFES 1h/d, 1d/wk, for 12-13wk. 48h after final exposure, bronchoalveolar lavage fluid (BALF) lung injury and inflammation, gene expression, and lung/nasal pathology were assessed. RESULTS:Acute WFES exposure increased BALF markers of lung injury and neutrophilic inflammation. Subchronic HT resulted in >30% lower weight gain and decreased body fat relative to RT; effects were greater in episodically WFES-exposed rats. Whole body plethysmography revealed HT-induced changes in breathing parameters; WFES exacerbated these effects. Small effects were observed on BALF markers of lung injury/inflammation, consistent with minimal pathological findings in lung and nasal cavity. All three stressors, individually and in combination, inhibited gene expression of proteins involved in glucocorticoid-mediated regulation of neuroendocrine stress response and peripheral homeostatic physiology. CONCLUSION:These findings suggest functional impairment at HT, exacerbated by WFES, linked to dysregulation of stress without affecting structural integrity of respiratory tract.
BACKGROUND:Ambient air pollution is associated with reduced lung function, but whether sex modifies the association with threshold-based exposures remains unclear. This cross-sectional study examined sex-specific associations between threshold-based exposures to fine particulate matter (PM2.5), nitrogen dioxide (NO2), ozone (O3), and lung function. METHODS:Data from 21,339 adults aged 45-85 years in the Canadian Longitudinal Study on Aging were analyzed. Annual average air pollutant concentrations representing multi-year exposure estimates (2012-2015) were assigned to participants based on their residential postal codes. Decision tree regression was used to derive exposure cut points and classify participants into low, intermediate, and high exposure thresholds for each pollutant with respect to lung function (FEV1, FVC, and FEV1/FVC ratio). Survey-weighted multivariable linear regression models were used to estimate sex-specific associations with percent-predicted lung function, including interaction terms between sex and exposure thresholds. RESULTS:Significant sex interactions were observed for PM2.5 and NO2 with percent-predicted FEV1 and FVC, and for O3 with percent-predicted FVC and the FEV1/FVC ratio. Among males, high vs. low PM2.5 exposure was associated with lower FEV1 (-3.11%; 95% CI: -4.47, -1.74) and FVC (-2.72%; 95% CI: -3.76, -1.69). Among females, a significant but smaller FVC reduction was observed (-1.53%; 95% CI: -2.59, -0.47) but not for FEV1. High vs. low NO2 exposure was associated with greater reductions in FEV1 among males (-5.00%; 95% CI: -7.16, -2.84) than among females (-1.99%; 95% CI: -2.79, -1.19), and significantly reduced FVC among males(-3.58%; 95% CI: -5.15, -2.00) but not among females (-1.64%; 95% CI: -3.39, 0.11). High vs. low O3 exposure was associated with reduced FVC in both sexes, with a stronger association among males (-3.34%; 95% CI: -4.37, -2.31) than among females (-2.60%; 95% CI: -3.56, -1.65). CONCLUSIONS:Sex significantly modified the inverse associations between ambient air pollution exposure thresholds and lung function, with greater reductions observed in males. These associations occurred at exposure thresholds at or below current regulatory standards, underscoring the need for continuous reassessment of air quality guidelines to better protect respiratory health.
OBJECTIVE:Heat-not-burn tobacco products (IQOS) have emerged as potentially reduced-risk alternatives to combustible cigarettes (CSs), yet their inhalation toxicity profile remains incompletely characterized. MATERIALS AND METHODS:This study evaluated the comparative respiratory and systemic effects of IQOS aerosol vs. CS smoke through whole-body inhalation exposure in an experimental rat model. Twenty-one male Wistar albino rats (8-10 weeks, 250-300 g) were randomly assigned to three groups (n = 7): control (ambient air), CS exposure (10 mg nicotine/day, ∼6 cigarettes/session), and IQOS exposure (equivalent nicotine dose, ∼8 HeatSticks/session). A custom-designed whole-body inhalation exposure system, developed in collaboration with Istanbul Technical University, delivered standardized aerosols following Health Canada Intense puffing parameters (55 mL puff volume, 27.5 mL/s flow rate, 2-s puff duration, 30-s inter-puff interval) during daily 1.5-h sessions over 21 consecutive days. Peripheral blood samples were collected on Days 7, 14, and 21 for assessment of plasma inflammatory markers (IL-1β, IL-6, TNF-α, and hs-CRP), oxidative stress parameters (total oxidant status [TOS], total antioxidant status, oxidative stress index), and DNA damage in isolated mononuclear leukocytes using the alkaline comet assay. Plasma cotinine was quantified as the primary biomarker of systemic nicotine absorption. Terminal lung tissue analysis on Day 21 evaluated local respiratory oxidative stress, inflammatory cytokine concentrations, and tissue cotinine deposition. . RESULTS:Plasma TOS increased progressively in both exposure groups (CS: 9.2 ± 1.82 to 14.71 ± 1.65 µmol H2O2 Eq/L; IQOS: 6.81 ± 1.25 to 11.49 ± 1.30 µmol H2O2 Eq/L), with CS demonstrating significantly higher oxidative burden. DNA damage in circulating cells escalated markedly (CS: 21.74 ± 2.51% to 47.76 ± 3.67% tail DNA; IQOS: 16.22 ± 1.87% to 33.44 ± 2.41% tail DNA). Lung tissue analysis revealed significant 'elevation of inflammatory markers and oxidative stress parameters' in both exposure groups. While IQOS inhalation induced less severe toxicity than CS smoke, it produced significant respiratory and systemic adverse effects including oxidative stress, inflammatory responses, and DNA damage. DISCUSSION AND CONCLUSION:These findings challenge claims of substantially reduced harm for heat-not-burn products and support continued regulatory oversight of inhaled tobacco delivery systems.
OBJECTIVE:Some of the varieties of talc were reported to contain a small fraction of elongate particles, including tremolite. The biological effects of tremolite were demonstrated in literature as dependent on the habit of particles (asbestiform vs. non-asbestiform). The objective of this paper is to utilize advanced methodologies of risk evaluation to determine if risk of mesothelioma could be elevated in persons utilizing talcum powder. METHODS:Monte Carlo simulation was used to calculate potency factors, cumulative exposure, and mesothelioma risk for a hypothetical scenario. RESULTS:Excess risk of mesothelioma for the person would be estimated as 0.22 cases per 1,000,000 per lifetime, with 5th percentile of 0.003 and 95th percentile of 0.873. Upper bound of excess mesothelioma risk is lower than the U.S. EPA benchmark for the general population and also comprises only about 1.4% of the mesothelioma baseline level in unexposed people. The morphological habit of tremolite particles reported in talc was typical for non-asbestiform variety. CONCLUSIONS:Quantitative risk assessment can be used to evaluate possible health outcomes of airborne exposure to talcum powder.
BACKGROUND:Sepsis is a life-threatening syndrome of immune dysregulation; preexisting lymphopenia and an elevated neutrophil-to-lymphocyte ratio (NLR) heighten host susceptibility. Chronic low-dose exposure to lead (Pb), cadmium (Cd), and mercury (Hg) is immunotoxic, but its association with these pre-sepsis markers in the general population remains unclear. METHODS:We analyzed 12,580 adults from NHANES 2011-2018. Outcomes were lymphopenia (absolute lymphocyte count <1.0 × 109/L) and high NLR (top quartile). Survey-weighted logistic and Weighted Quantile Sum (WQS) regressions evaluated individual and joint mixture effects. Restricted cubic splines modeled dose-response relationships. Continuous exposure models were also constructed to minimize information loss. RESULTS:Fully adjusted models showed higher quartiles of Pb, Cd, and Hg were each associated with greater odds of lymphopenia and high NLR. Comparing highest to lowest quartiles, ORs for lymphopenia were 1.85 (95% CI 1.42-2.41) for Pb, 1.66 (95% CI 1.28-2.15) for Cd, and 1.52 (95% CI 1.15-2.01) for Hg. Continuous models confirmed that each log2-fold increase in blood metals was associated with significantly reduced absolute lymphocyte counts and elevated NLR (all p < 0.05). The WQS index was positively associated with lymphopenia (OR 1.63) and high NLR (OR 1.48). CONCLUSION:In a nationally representative sample, chronic low-level exposure to Pb, Cd, and Hg was independently associated with an immune profile linked to sepsis susceptibility, suggesting environmental metal reduction as a potential population-level strategy to reduce sepsis risk.
AIMS:Size-fractionated ambient particulate matter (PM) was collected from two of the most highly PM-polluted agricultural regions in California the Imperial Valley (PMIV), and San Joaquin Valley (Parlier, PMPA), to compare the effects of particle source, size, and duration of exposure on inflammatory gene expression, cell viability, and aryl hydrocarbon receptor (AhR) activation. METHODS:Here we tested that the chemical composition of the PM would provoke different effects unique to the PM size fraction and with an association between exposure time, activation of AhR, and the expression of inflammatory genes. Human U937-derived macrophages were used to measure inflammatory biomarkers, cell viability and engulfment of PM. Particles across three size fractions - ultrafine (≥ 0.1 µm), fine (0.1-2.5 µm), and coarse (2.5-10 µm) were tested. RESULTS:Gene expression varied by PM source, size, and duration of exposure. PMIV typically induced a greater level of gene expression than PMPA of the same size fraction. For the 12-h experiments, ultrafine and coarse particle fractions were the most potent stimulators of gene expression compared to the control, irrespective of PM source. The results show that ultrafine/fine PMIV and fine PMPA typically produced the greatest increase in mRNA levels compared to the control in an AhR-dependent manner. CONCLUSIONS:Ultrafine and fine PM from both sites (PMIV and PMPA) preferentially engaged AhR-dependent signaling, whereas coarse PM activated NF-κB-mediated inflammatory pathways. Overall, this study demonstrates PM size- and time-dependent effects on inflammatory gene expression and highlights a distinction between AhR- and NF-κB-driven responses across PM fractions.
OBJECTIVE:Ferrets have long served as an important animal model for the study of respiratory infections, inhalation toxicology, and aerosolized therapeutics because of their anatomical and physiological similarities to humans. Despite their widespread use, quantitative models describing particle deposition within the ferret lung remain limited. In this study, we developed a mechanistic dosimetry model to predict total and regional deposition of inhaled inert particles in the ferret lower respiratory tract (LRT). MATERIALS AND METHODS:Two anatomically based lung geometries were constructed using available morphometric data: a modified typical-path symmetric lung geometry and a more physiologically representative 2-path symmetric lung geometry. Both models were designed to yield realistic lung volumes and airway counts while accommodating the limited availability of airway measurements. Airway dimensions were derived from published morphometric data and extended using sigmoidal curve fits to represent the complete tracheobronchial (TB) and pulmonary (PUL) regions. Lung ventilation was modeled assuming uniform pleural pressure, with airflow distributed proportionally to distal lung volume. Particle transport and deposition were simulated using a one-dimensional (1D) advection-diffusion framework incorporating gravitational settling, inertial impaction, and Brownian diffusion. RESULTS AND DISCUSSION:The 2-path symmetric lung geometry enables more realistic predictions of particle deposition throughout the lung, particularly with respect to deposition as a function of lung depth, allowing direct comparison of predicted deposition with in vivo imaging measurements.
OBJECTIVE:Elevated levels of ambient ozone (O3), a criteria air pollutant produced by industries and automobiles, are significantly correlated with increased respiratory morbidity. Acute O3 exposure disrupts airway epithelial integrity, compromising lung function and aggravating existing lung diseases. Despite prior work, the detailed kinetics of O3-induced acute lung injury and resolution remain unclear. METHODS:To delineate the temporal progression and resolution of O3-induced acute lung injury in mice, we exposed eight-week-old female mice to filtered air or 1.5 ppm O3 for 4h and assessed lung injury markers at 12h, 36h, 60h, 108h, and 204h post-exposure. RESULTS:Analysis of bronchoalveolar lavage fluid (BALF) revealed that neutrophil counts peaked at 12h and protein concentration at 36h, followed by a progressive decrease from 60h to baseline levels at 204h. The acute O3 exposure also induced time-dependent alterations in multiple cytokines, including eotaxin, G-CSF, KC, MIP-1α, MIP-1β, IL-5, IL-6, IL-12, and MCP-1. At 12h post-exposure, severe denudation of airway epithelial cells was observed. Basal cell proliferation peaked between 36h and 60h, while ciliated cell restoration began at 60h, with normal epithelial composition achieved by 204h. CONCLUSION:This study elucidates the temporal sequence of events in O3-induced acute lung injury, demonstrating a progression from initial epithelial damage and inflammatory cell infiltration to subsequent epithelial regeneration and inflammation resolution over 204h. These findings provide important insights into the kinetics of O3-induced acute lung injury and repair mechanisms.
OBJECTIVE:This study investigated whether N-acetylcysteine (NAC) protects against the harmful effects induced by long-term inhalation of low-dose formaldehyde (FA). MATERIALS AND METHODS:Male C57BL/6 mice were divided into six groups: control (CG), vehicle (VG), FA-exposed (1% FA by inhalation), and three FA-exposed groups treated with NAC (100, 150, or 200 mg/kg; FN100, FN150, and FN200, respectively) administered by orogastric gavage during six months. Ventilatory and biometric parameters were assessed; biological samples were collected for analysis. RESULTS:FA exposure reduced body mass and increased relative lung mass. Total and differential leukocyte counts in peripheral blood were reduced, whereas inflammatory cell influx to the airways was increased. Oxidative stress was evidenced by elevated carbonyl protein and TBARS levels. There was an increased superoxide dismutase activity, and reduced catalase activity. Redox imbalance was further characterized by increased sulfhydryl group levels, and there was a decreased reduced glutathione system. FA exposure also induced a marked inflammatory response, with elevated levels of IL-6, IL-15, IL-13, and IL-10. Structural lung damage was indicated by decreased alveolar airspace volume density and mean linear intercept, along with increased septal volume density, and it was associated with altered ventilatory parameters, including reduced respiratory rate and increased tidal volume. MMP-9 activity was reduced following FA exposure. NAC administration attenuated oxidative stress, inflammatory mediator release, pulmonary inflammation, and lung tissue damage. CONCLUSION:These findings demonstrate that NAC exerts protective effects by modulating redox imbalance and inflammatory responses, thereby preventing lung injury and respiratory dysfunction induced by long-term FA inhalation.
OBJECTIVE:Inhalation risk assessments that do not account for human relevant particle size distributions (PSDs) in the inhalation dosimetry adjustment can overestimate risk. This stems from a mismatch between animal toxicity studies that use small particle sizes for hazard identification and the larger PSDs characteristic of agricultural spray application exposures. METHODS:This work introduces a novel approach employing Multiple-Path Particle Dosimetry (MPPD) software to derive human equivalent concentrations (HECs) that incorporate a Particle-size Adjustment Factor (PAF) in addition to the dosimetric adjustment factor (DAF), which is the traditional approach to derive the inhalation risk assessment endpoint. While the DAF accounts for the differences in rat and human respiratory physiology, the PAF accounts for differences in aerosol PSDs between occupational exposure scenarios and rodent inhalation studies. The MPPD model was used to derive the DAF and PAFs for different pesticide application methods to generate HECs for use in risk assessments. RESULTS/DISCUSSION:The results demonstrate that PAF integration results in refined exposure-relevant and scenario-specific risk assessments and identified scenarios with negligible potential for exceeding the inhalation exposure hazard thresholds. While more data on human-relevant PSDs for several pesticide application scenarios are needed, this method, coupled with new approach methods (NAMs) to predict portal of entry effects, and dosimetry and kinetic modeling to understand systemic dose, supports existing weight-of-evidence frameworks for reducing animal studies in pesticide registration. Advancing exposure assessment using the best available methods ensures robust human health protection while reducing animal usage.
AIMS:Multiple cases of hematopoietic cancer have been reported among subway maintenance workers (MWs) at a company in Korea employing about 3,400 people, prompting a need to examine the relationship between HC and maintenance job characteristics. This study aimed to identify and assess the presence and levels of hematopoietic carcinogens, including benzene, in chemical products and workplace air within subway maintenance process and to provide scientific evidence to support forthcoming epidemiological investigations of HC. METHODS:A total of 169 chemical products used in cleaning, painting, and inspection processes were collected and analyzed using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Air samples were collected during maintenance tasks and analyzed using GC-MS in SIM mode. Target substances included benzene, trichloroethylene, dichloromethane (DCM), styrene, and tetrachloroethylene. RESULTS:Benzene and DCM at concentrations ≥0.1% were detected in 12.4% of the 169 chemical products analyzed, including three products containing benzene and 18 containing DCM at this level. Airborne concentrations of benzene and DCM were detected in over 50% of the samples collected from painting (n=26) and cleaning operations (n=39), but all were below Occupational Exposure Limits. CONCLUSIONS:The findings provide quantitative and qualitative characterization of current exposure conditions and may support the reconstruction of potential past exposure scenarios to hematopoietic carcinogens among subway MWs, thereby informing subsequent epidemiological investigations.
BACKGROUND:The progression of sepsis seriously threatens people's life. In addition, acute lung injury can contribute to the injury of epithelial cells. Meanwhile, oleanic acid can inhibit the inflammatory responses in ALI, while the mechanism underlying the function of oleanic acid remains unclear. METHODS:For investigating the impact of oleanic acid in ALI, pulmonary epithelial cells were treated with LPS. Then, CCK8 assay was employeed to detect the cell viability. RT-qPCR and western blot were applied for testing the mRNA and protein levels, respectively. Furthermore, ELISA was used to test the inflammatory factors in pulmonary epithelial cells. RESULTS:Oleanic acid could significantly inhibit LPS-caused inflammation in pulmonary epithelial cells. LPS significantly induced pyroptosis in pulmonary epithelial cells via upregulation of NLRP3, ASC, cleaved caspase-1 and cleaved GSDMD, which was reversed by oleanic acid. In addition, oleanic acid notably reversed LPS-activated NF-κB signaling in cells. LPS obviously inhibited the level of TNFAIP3 in pulmonary epithelial cells, which was significantly reversed by oleanic acid. Knockdown of TNFAIP3 aggravated LPS-caused inflammation in pulmonary epithelial cells through activation of NF-κB signaling. CONCLUSION:Oleanic acid inhibits LPS-caused inflammation and pyroptosis in pulmonary epithelial cells via mediation of TNFAIP3/NF-κB axis, which may serve as a new agent against ALI.
OBJECTIVE:Benzene, toluene, ethylbenzene, and xylene (BTEX) are ubiquitous pollutants, and leakage of underground storage tanks has increased the risk of inhalation exposure and health effects that are likely impacted by ambient temperature. METHODS:In this study, male and female C57BL6J mice were housed at either normal (NT - 70 °F/22 °C) or high temperature (HT - 90 °F/32 °C) for five weeks, followed by nose-only exposure to either filtered air (FA) or BTEX (316 ppm) for four hours on two consecutive days. Whole-body plethysmography was performed after the first exposure and high-frequency echocardiography after the second. RESULTS:HT significantly increased tidal volume (TV), and inspiratory/expiratory times (Ti/Te) and flows (PIF/PEF) and decreased enhanced pause (Penh) in female and male mice. At NT, BTEX increased frequency (f) and decreased Ti and Te in female mice but not male. At HT, BTEX decreased f and Penh and increased TV, Te, Ti, and relaxation time (RT) in female mice, and only increased TV, PEF, PIF in males. HT caused a significant decrease in heart rate in female mice, while BTEX reversed that effect. Dobutamine increased HR in all HT females and cardiac output (CO) in males. BTEX decreased HR and CO in the latter. DISCUSSION:Thus, BTEX altered breathing and cardiovascular function in a sex-dependent manner, causing rapid ventilation in females, irrespective of temperature, whereas BTEX caused cardiovascular decrements in only HT males challenged with exercise-like stress. These results indicate that sex and ambient temperature play a role in BTEX cardiopulmonary effects, which underscores their importance for air pollution risk.
BACKGROUND:Air pollution is a major global health concern and a well-established risk factor for cardiovascular disease (CVD). While earlier bibliometric efforts provided useful insights into early research patterns using MeSH term clustering, they were limited in scope and time frame. A more comprehensive synthesis is needed to reflect the expanding and evolving nature of this field. OBJECTIVES:To map the global research landscape on air pollution and cardiovascular health, identifying trends, key contributors, and thematic developments through bibliometric analysis. METHODS:A bibliometric study was conducted using the Scopus database, including 6,663 publications from 1963 to 2025. Data was analyzed using Bibliometrix (R), VOSviewer, and CiteSpace. Analytical approaches included performance analysis, coauthorship networks, co-citation mapping, keyword co-occurrence, and thematic evolution analysis. RESULTS:The dataset showed an annual growth rate of 6.83%, with contributions from 22,322 authors across 1,658 sources. Environmental Health Perspectives was the most prolific journal. Keyword analysis revealed dominant themes such as PM2.5, cardiovascular outcomes (e.g. hypertension, myocardial infarction), and biological mechanisms (e.g. inflammation, oxidative stress). Thematic evolution reflected a shift from acute exposure studies to broader interdisciplinary concerns like climate change, urban planning, and environmental justice. Collaboration networks highlighted strong interregional partnerships, particularly among North American, European, and Asian researchers. However, contributions from low-income regions remain limited. CONCLUSION:This study provides an expanded and updated overview of research linking air pollution to cardiovascular health. By building on earlier bibliometric work, it highlights emerging interdisciplinary priorities and underscores the need for equitable, evidence-based policy responses to environmental health risks.
OBJECTIVE:The laryngeal epithelium is one of the first lines of defense against inhaled insults, including cigarette smoke (CS). However, a lack of suitable in vitro models has limited mechanistic studies of laryngeal epithelial injury and disease pathogenesis in response to CS. The purpose of this investigation was to establish an air-liquid interface (ALI) system for modeling airborne CS exposure in laryngeal epithelial cells. METHODS:Primary mouse laryngeal epithelial cells were harvested, cultured, and transitioned from submerged to ALI conditions to induce epithelial differentiation. ALI cultures were characterized by electrophysiological evaluation of transepithelial resistance (TEER), histology, and immunofluorescent staining and quantification for epithelial markers and compared with native laryngeal tissue. ALI cultures were exposed to increasing doses of CS during differentiation, and epithelial barrier integrity was assessed by evaluating cytotoxicity, TEER, and structure. RESULTS:Submerged laryngeal epithelial cultures were primarily proliferating basal cells. Differentiated ALI cultures demonstrated progressive epithelial maturation, with formation of a multilayered structure and high TEER, indicative of robust barrier integrity. Epithelial marker localization in ALI cultures closely resembled that of native mouse vocal fold epithelium. CS exposure disrupted epithelial barrier integrity in a dose-dependent manner, including increased cytotoxicity and reductions in TEER. Moderate exposure permitted some recovery of function and structure, underscoring the intrinsic resilience of laryngeal epithelial cells. CONCLUSION:This investigation establishes a physiologically relevant in vitro model system that recapitulates key features of native laryngeal epithelium and provides a robust platform for investigating the cellular and molecular pathways governing CS-induced epithelial injury and repair.
OBJECTIVE:The aim of this laboratory study was to characterize the effects of sub-chronic electronic cigarette (E-cig) aerosol exposures on genome-wide DNA methylation in mice to begin to elucidate the pathophysiology of E-cig-related pulmonary diseases and cancer. MATERIALS AND METHODS:Male C57BL/6 and FVBN mice were randomly assigned to one of two treatment groups (n = 6 per group) and exposed daily to either filtered air or a 50:50 mixture of propylene glycol and vegetable glycerol containing 24 mg/mL nicotine (+Nic). Whole-body inhalation exposures were conducted for 3 h/d, 5 d/week, for a total of 1-month. Sequences for ∼285 000 CpG probes were aligned to the mouse genome, and mixed linear models were used to model DNA methylation levels (β values). These evaluations were followed by ingenuity pathway analysis (IPA), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Ontology (GO) analysis. RESULTS AND DISCUSSION:E-cig inhalation exposure induced significant DNA methylation changes in adult male mice, with a notable impact on cancer-related pathways. A total of 2300 genes in C57BL/6 mice and 6732 genes in FVBN mice were hypomethylated, while 1673 and 5529 genes were hypermethylated, respectively. KEGG and GO analyses highlighted key pathways such as Wnt/β-catenin signaling and proteoglycans in cancer, suggesting that E-cig aerosol exposure could disrupt critical genomic regulation and potentially promote carcinogenesis. These in vivo findings underscore the potential cancer-promoting effects of E-cig aerosols through epigenetic modifications. CONCLUSIONS:Findings from this study provide compelling evidence that sub-chronic E-cig exposure induces genomic DNA methylation changes linked to cancer pathways in two strains of adult male mice, highlighting the serious adverse consequences of E-cig use and strain-specific response differences.
OBJECTIVE:This study aimed to investigate the role of the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling cascade in the inflammatory responses induced by whole gasoline engine exhaust (GEE) in lung epithelial cells via air-liquid interface (ALI) exposure. MATERIALS AND METHODS:Using an ALI exposure system, human bronchial epithelial cells (BEAS-2B) and type II alveolar epithelial cells (A549) were exposed to whole GEE collected from a two-wheeled motorcycle at various dilution ratios. After a 1 h exposure at 10 mL/min, cell relative viability, intracellular reactive oxygen species (ROS), glutathione (GSH), oxidized glutathione (GSSG) and the GSH/GSSG ratio were measured. Inflammatory cytokines (IL-1β, IL-6, and IL-8) were quantified. The Nrf2 inhibitor brusatol (BR, 300 nM) and the antioxidant N-acetyl-L-cysteine (NAC, 5 mM) were used to modulate the Nrf2/HO-1 pathway and oxidative stress, respectively. Protein and gene expression levels were analyzed by Western Blotting and real-time PCR. RESULTS:Exposure to 10%GEE induced oxidative stress and optimally activated Nrf2/HO-1 expression without cytotoxicity, while higher concentrations suppressed this signaling pathway. Significant correlations were observed between Nrf2/HO-1 levels and inflammatory cytokines. Inhibition of Nrf2/HO-1 with BR reduced inflammatory responses which induced by the 10%GEE in both BEAS-2B and A549 cell lines. Furthermore, attenuating oxidative stress with NAC inhibited both Nrf2/HO-1 expression and the GEE-induced inflammatory response. CONCLUSION:Inhibiting the Nrf2/HO-1 signaling cascade attenuates the pro-inflammatory response induced by GEE in lung epithelial cells following ALI exposure. The Nrf2/HO-1 pathway appears to be a critical regulator of GEE-induced pulmonary inflammation, highlighting its potential as a therapeutic target.
Background: Myocardial injury following carbon monoxide (CO) poisoning is associated with increased mortality, yet early predictors remain poorly characterized. This study aimed to develop predictive models for early risk stratification using readily available clinical data. Methods: In a retrospective analysis of 714 patients with acute CO poisoning (2019-2024), we evaluated clinical and laboratory variables to identify predictors of myocardial injury (defined as cTnI ≥ 0.05 ng/mL) and 90-d mortality. Multivariable logistic regression was used to identify independent predictors, and model performance was assessed via ROC analysis. Results: Myocardial injury occurred in 132 patients (18.5%). Patients with injury were older (median age: 65 vs. 54 years, p < 0.001), had higher lactate levels (2.5 vs. 1.8 mmol/L, p < 0.001), higher carboxyhemoglobin concentrations (26.65% vs. 21.75%, p < 0.001), and more frequent hypocapnia (50.8% vs. 24.7%, p < 0.001). In the multivariable model adjusting for clinically relevant and univariately significant variables, age (per year increase; aOR = 1.02, 95% CI: 1.01-1.03), hypocapnia (aOR = 2.23, 95% CI: 1.23-4.07), and severe neurological impairment (aOR = 3.86, 95% CI: 2.12-7.05) were independently associated with myocardial injury. For 90-day mortality, independent predictors were age (per year increase; aOR = 1.14, 95% CI: 1.08-1.21) and severe neurological impairment (aOR = 7.53, 95% CI: 2.50-22.67). The models demonstrated good predictive accuracy for myocardial injury (AUC = 0.750, 95% CI: 0.703-0.797) and excellent predictive ability for mortality (AUC = 0.895, 95% CI: 0.846-0.944). Conclusions: The clinical risk model incorporating advancing age, severe neurological impairment, and hypocapnia enables risk stratification for myocardial injury, a critical intermediate marker of mortality in acute CO poisoning.
