Toxicity of urban air pollution particulate matter in developing and adult mouse brain: Comparison of total and filter-eluted nanoparticles

Inhaled Pollutants of the Gero-Exposome and Later-Life Health

Inhaled air pollutants (AirP) comprise extraordinarily diverse particles, volatiles, and gases from traffic, wildfire, cigarette smoke, dust, and various other sources. These pollutants contain numerous toxic components, which collectively differ in relative levels of components, but broadly share chemical classes. Exposure and health outcomes from AirP are complex, depending on pollutant source, duration of exposure, and socioeconomic status. We discuss examples in the current literature on organ responses to AirP, with a focus on lung, arteries, and brain. Some transcriptional responses are shared. It is well accepted that AirP contributes to Alzheimer's disease and other neurodegenerative conditions in the Gero-Exposome. However, we do not know which chemical compounds initiate these changes and how activation of these transcriptional pathways is further modified by genetics and prenatal development.

Association between urinary metals and prostate-specific antigen in aging population with depression: a cross-sectional study

Objective

This study aims to investigate the impact of depression and urinary metals on Prostate-Specific Antigen (PSA).

Methods

Analysis was conducted on 1901 samples collected from the National Health and Nutrition Examination Survey (NHANES) database between 2001 and 2010. Analytical methods included stepwise multiple linear regression (MLR) analysis of the overall population's urinary metals and PSA relationship, analysis of urinary metals and PSA relationship in older adults and BMI subgroups, analysis of urinary metals and PSA relationship in the depressed population, and restricted cubic spline (RCS) analysis. A significance level of p < 0.05 was considered statistically significant.

Results

In the stepwise multiple linear regression, beryllium (Be) showed a dose-response association with PSA (third quartile: β = 0.05, 95%CI (0.02, 0.09); fourth quartile: β = 0.07, 95%CI (0.02, 0.12), p trend = 0.048). Subgroup analysis indicated that in individuals aged >60, Be at Q4 level [β = 0.09, 95%CI (0.05, 0.21)] exhibited a dose-response correlation with PSA. In the population with 25 ≤ BMI < 30, Be might more significantly elevate PSA, with Q4 level having a pronounced impact on PSA levels [β = 0.03, 95%CI (0.02, 1.27)]. In the depressed population, urinary cadmium (Cd) levels showed a significant positive dose-response relationship, with Q4 level of Cd having the maximum impact on PSA [β = 0.3, 95%CI (0.09, 0.49)].

Conclusion

Individuals exposed to beryllium (Be), especially the older adults and overweight, should monitor their PSA levels. In depressed patients, cadmium (Cd) levels may further elevate PSA levels, necessitating increased monitoring of PSA levels among males.

Dyslexia is associated with urinary polycyclic aromatic hydrocarbon metabolite concentrations of children from China: Data from the READ program

It has been found that exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with the risk of certain childhood neurodevelopmental disorders. However, no research has investigated the relationship between exposure to PAHs and children's dyslexia odds. The objective of this research was to investigate whether urinary mono-hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) are associated with increased dyslexia odds in Chinese children. We recruited 1,089 children (542 dyslexic children and 547 non-dyslexic children) for this case-control study. Ten OH-PAHs were measured in the participants' urine samples, which were collected between November 2017 and March 2023. Odds ratios (ORs) of the associations between the OH-PAHs and dyslexia were calculated using logistic regression models, after adjustment for the potential confounding factors. A significant association was found between urinary concentrations of 2-hydroxynaphthalene (2-OHNap) and the elevated odds of dyslexia. The children in the highest quartile of 2-OHNap had a higher OR of dyslexia (1.87, 95% CI: 1.07-3.27) than those in the lowest quartile (P-trend = 0.02) after adjustment for the covariates. After excluding children with maternal disorders during pregnancy, logistic regression analyses showed similar results. Our results suggested a possible association between PAH exposure and the elevated odds of dyslexia.

Early-life exposure to PM2.5 leads to ASD-like phenotype in male offspring rats through activation of PI3K-AKT signaling pathway

Previous studies have shown that early-life exposure to fine particulate matter (PM2.5) is associated with an increasing risk of autism spectrum disorder (ASD), however, the specific sensitive period of ASD is unknown. Here, a model of dynamic whole-body concentrated PM2.5 exposure in pre- and early-postnatal male offspring rats (MORs) was established. And we found that early postnatal PM2.5 exposed rats showed more typical ASD behavioral characteristics than maternal pregnancy exposure rats, including poor social interaction, novelty avoidance and anxiety disorder. And more severe oxidative stress and inflammatory responses were observed in early postnatal PM2.5 exposed rats. Moreover, the expression level of phosphatase and tensin homolog deleted on chromosome ten (PTEN) was down-regulated and the ratios of p-PI3K/PI3K and p-AKT/AKT were up-regulated in early postnatal PM2.5 exposed rats. This study suggests that early postnatal exposure to PM2.5 is more susceptible to ASD-like phenotype in offspring than maternal pregnancy exposure and the activation of PI3K-AKT signaling pathway may represent underlying mechanisms.

Neurodegenerative effects of air pollutant Particles: Biological mechanisms implicated for Early-Onset Alzheimer's disease

BACKGROUND

Sporadic Alzheimer's disease (AD) occurs in 99% of all cases and can be influenced by air pollution such as diesel emissions and more recently, an iron oxide particle, magnetite, detected in the brains of AD patients. However, a mechanistic link between air pollutants and AD development remains elusive.

AIM

To study the development of AD-relevant pathological effects induced by air pollutant particle exposures and their mechanistic links, in wild-type and AD-predisposed models.

METHODS

C57BL/6 (n = 37) and APP/PS1 transgenic (n = 38) mice (age 13 weeks) were exposed to model pollutant iron-based particle (Fe0-Fe3O4, dTEM = 493 ± 133 nm), hydrocarbon-based diesel combustion particle (43 ± 9 nm) and magnetite (Fe3O4, 153 ± 43 nm) particles (66 µg/20 µL/third day) for 4 months, and were assessed for behavioural changes, neuronal cell loss, amyloid-beta (Aβ) plaque, immune response and oxidative stress-biomarkers. Neuroblastoma SHSY5Y (differentiated) cells were exposed to the particles (100 μg/ml) for 24 h, with assessments on immune response biomarkers and reactive oxygen species generation.

RESULTS

Pollutant particle-exposure led to increased anxiety and stress levels in wild-type mice and short-term memory impairment in AD-prone mice. Neuronal cell loss was shown in the hippocampal and somatosensory cortex, with increased detection of Aβ plaque, the latter only in the AD-predisposed mice, with the wild-type not genetically disposed to form the plaque. The particle exposures however, increased AD-relevant immune system responses, including inflammation, in both strains of mice. Exposures also stimulated oxidative stress, although only observed in wild-type mice. The in vitro studies complemented the immune response and oxidative stress observations.

CONCLUSIONS

This study provides insights into the mechanistic links between inflammation and oxidative stress to pollutant particle-induced AD pathologies, with magnetite apparently inducing the most pathological effects. No exacerbation of the effects was observed in the AD-predisposed model when compared to the wild-type, indicating a particle-induced neurodegeneration that is independent of disease state.

Air pollution, dementia, and lifespan in the socio-economic gradient of aging: perspective on human aging for planning future experimental studies

Air pollution (AirPoll) accelerates human aging, as assessed by increased adult mortality and earlier onset of cardiovascular diseases, and dementia. Socio-economic strata (SES) of wealth and education have parallel differences of mortality and these diseases. Children from impoverished homes differ in brain development at birth and in risk of early fat excess and hypertension. To further enhance the healthspan, biogerontologists may consider a wider range of environmental exposures from gestation through later life morbidity that comprise the Gero-Exposome. Experimental studies with rodents and nematodes document shared transcriptional responses to AirPoll. In rodents, AirPoll exposure activates gene systems for body-wide detoxification through Nrf2 and NFkB transcription factors that mediate multiple aging processes. Gestational environmental factors include maternal diet and exposure to AirPoll and cigarette smoke. Correspondingly, gestational exposure of mice to AirPoll increased adult body fat, impaired glucose clearance, and decreased adult neurogenesis in the hippocampus, a brain region damaged in dementia. Nematode larvae also respond to AirPoll with Alzheimer relevant responses. These experimental approaches could identify to interventions for expanded human health and longevity across SES gradients.

Particulate matter exposure and neurodegenerative diseases: A comprehensive update on toxicity and mechanisms

Exposure to particulate matter (PM) has been associated with a range of health impacts, including neurological abnormalities that affect neurodevelopment, neuroplasticity, and behavior. Recently, there has been growing interest in investigating the possible relationship between PM exposure and the onset and progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. However, the precise mechanism by which PM affects neurodegeneration is still unclear, even though several epidemiological and animal model studies have provided mechanistic insights. This article presents a review of the current research on the neurotoxicity of PM and its impact on neurodegenerative diseases. This review summarizes findings from epidemiological and animal model studies collected through searches in Google Scholar, PubMed, Web of Science, and Scopus. This review paper also discusses the reported effects of PM exposure on the central nervous system and highlights research gaps and future directions. The information presented in this review may inform public health policies aimed at reducing PM exposure and may contribute to the development of new treatments for neurodegenerative diseases. Further mechanistic and therapeutic research will be needed to fully understand the relationship between PM exposure and neurodegenerative diseases.

Uncovering the link between air pollution and neurodevelopmental alterations during pregnancy and early life exposure: A systematic review

Air pollution plays, nowadays, a huge role in human's health and in the personal economy. Moreover, there has been a rise in the prevalence of neurodevelopmental disorders like the Autism Spectrum Disorder (ASD) in recent years. Current scientific studies have established a link between prenatal or perinatal exposure to environmental pollutants and ASD. This systematic review summarizes the current literature available about the relationship between exposure to air pollutants (particulate matter [PM], Second Organic Aerosols [SOA], Diesel Exhaust [DE], and Traffic Related Air Pollution [TRAP]) and neurodevelopmental disorders in preclinical models using rats and mice. The articles were selected and filtered using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, and bias-evaluated using the SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) tool. Overall, our findings suggest that air pollutants are associated with negative developmental outcomes characterized by ASD-like behaviors, abnormal biochemical patterns, and impaired achievement of developmental milestones in rodents. However, there is not sufficient information in certain domains to establish a clear relationship. Short phrases for indexing terms: Air pollution affects neurodevelopment; PM exposure modifies glutamate system; Prenatal exposure combined with postnatal affect more to behavioral / cognitive domain; Air pollution modifies social behavior in rodents; Cognitive deficits can be detected after gestational exposure to air pollution.

Association between spill-related exposure to fine particulate matter and peripheral motor and sensory nerve function among oil spill response and cleanup workers following the Deepwater Horizon oil spill

BACKGROUND

Burning/flaring of oil/gas during the Deepwater Horizon oil spill response and cleanup (OSRC) generated high concentrations of fine particulate matter (PM_2.5). Personnel working on the water during these activities may have inhaled combustion products. Neurologic effects of PM_2.5 have been reported previously but few studies have examined lasting effects following disaster exposures. The association of brief, high exposures and adverse effects on sensory and motor nerve function in the years following exposure have not been examined for OSRC workers.

OBJECTIVES

We assessed the relationship between exposure to burning/flaring-related PM_2.5 and measures of sensory and motor nerve function among OSRC workers.

METHODS

PM_2.5 concentrations were estimated from Gaussian plume dispersion models and linked to self-reported work histories. Quantitative measures of sensory and motor nerve function were obtained 4-6 years after the disaster during a clinical exam restricted to those living close to two clinics in Mobile, AL or New Orleans, LA (n = 3401). We obtained covariate data from a baseline enrollment survey and a home visit, both in 2011-2013. The analytic sample included 1186 participants.

RESULTS

We did not find strong evidence of associations between exposure to PM_2.5 and sensory or motor nerve function, although there was a suggestion of impairment based on single leg stance among individuals with high exposure to PM_2.5. Results were generally consistent whether we examined average or cumulative maximum exposures or removed individuals with the highest crude oil exposures to account for co-pollutant confounding. There was no evidence of exposure-response trends.

IMPACT STATEMENT

Remediating environmental disasters is essential for long-term human and environmental health. During the Deepwater Horizon oil spill disaster, burning and flaring of oil and gas were used to remove these pollutants from the environment, but led to potentially high fine particulate matter exposures for spill response workers working on the water. We investigate the potential adverse effects of these exposures on peripheral nerve function; understanding the potential health harm of remediation tactics is necessary to inform future clean up approaches and protect human health.

Air pollution nanoparticle and alpha-synuclein fibrils synergistically decrease glutamate receptor A1, depending upon nPM batch activity

Background

Epidemiological studies have variably linked air pollution to increased risk of Parkinson's disease (PD). However, there is little experimental evidence for this association. Alpha-synuclein (α-syn) propagation plays central roles in PD and glutamate receptor A1 (GluA1) is involved in memory and olfaction function.

Methods

Each mouse was exposed to one of three different batches of nano-particulate matter (nPM) (300 μg/m³, 5 h/d, 3 d/week), collected at different dates, 2017-2019, in the same urban site. After these experiments, these nPM batches were found to vary in activity. C57BL/6 female mice (3 mo) were injected with pre-formed murine α-synuclein fibrils (PFFs) (0.4 μg), which act as seeds for α-syn aggregation. Two exposure paradigms were used: in Paradigm 1, PFFs were injected into olfactory bulb (OB) prior to 4-week nPM (Batch 5b) exposure and in Paradigm 2, PFFs were injected at 4th week during 10-week nPM exposure (Batches 7 and 9). α-syn pSer129, microglia Iba1, inflammatory cytokines, and Gria1 expression were measured by immunohistochemistry or qPCR assays.

Results

As expected, α-syn pSer129 was detected in ipsilateral OB, anterior olfactory nucleus, amygdala and piriform cortex. One of the three batches of nPM caused a trend for elevated α-syn pSer129 in Paradigm 1, but two other batches showed no effect in Paradigm 2. However, the combination of nPM and PFF significantly decreased Gria1 mRNA in both the ipsi- and contra-lateral OB and frontal cortex for the most active two nPM batches. Neither nPM nor PFFs alone induced responses of microglia Iba1 and expression of Gria1 in the OB and cortex.

Conclusion

Exposures to ambient nPM had weak effect on α-syn propagation in the brain in current experimental paradigms; however, nPM and α-syn synergistically downregulated the expression of Gria1 in both OB and cortex.

A cross-sectional analysis of long-term exposure to ambient air pollution and cognitive development in children aged 3-4 years living in 12 low- and middle-income countries

Exposure to ambient air pollution may affect cognitive functioning and development in children. Unfortunately, there is little evidence available for low- and middle-income countries (LMICs), where air pollution levels are highest. We analysed the association between exposure to ambient fine particulate matter (≤2.5 μm [PM_2.5]) and cognitive development indicators in a cross-sectional analysis of children (aged 3-4 years) in 12 LMICs. We linked Demographic and Health Survey data, conducted between 2011 and 2018, with global estimates of PM_2.5 mass concentrations to examine annual average exposure to PM_2.5 and cognitive development (literacy-numeracy and learning domains) in children. Cognitive development was assessed using the United Nations Children's Fund's early child development indicators administered to each child's mother. We used multivariable logistic regression models, adjusted for individual- and area-level covariates, and multi-pollutant models (including nitrogen dioxide and surface-level ozone). We assessed if sex and urban/rural status modified the association of PM_2.5 with the outcome. We included 57,647 children, of whom, 9613 (13.3%) had indicators of cognitive delay. In the adjusted model, a 5 μg/m³ increase in annual all composition PM_2.5 was associated with greater odds of cognitive delay (OR = 1.17; 95% CI: 1.13, 1.22). A 5 μg/m³ increase in anthropogenic PM_2.5 was also associated with greater odds of cognitive delay (OR = 1.05; 95% CI: 1.00, 1.10). These results were robust to several sensitivity analyses, including multi-pollutant models. Interaction terms showed that urban-dwelling children had greater odds of cognitive delay than rural-dwelling children, while there was no significant difference by sex. Our findings suggest that annual average exposure to PM_2.5 in young children was associated with adverse effects on cognitive development, which may have long-term consequences for educational attainment and health.

Air Pollution-Related Neurotoxicity Across the Life Span

Air pollution is a complex mixture of gases and particulate matter, with adsorbed organic and inorganic contaminants, to which exposure is lifelong. Epidemiological studies increasingly associate air pollution with multiple neurodevelopmental disorders and neurodegenerative diseases, findings supported by experimental animal models. This breadth of neurotoxicity across these central nervous system diseases and disorders likely reflects shared vulnerability of their inflammatory and oxidative stress-based mechanisms and a corresponding ability to produce brain metal dyshomeo-stasis. Future research to define the responsible contaminants of air pollution underlying this neurotoxicity is critical to understanding mechanisms of these diseases and disorders and protecting public health.

Atmospheric particulate matter impairs cognition by modulating synaptic function via the nose-to-brain route

Atmospheric particulate matter (PM), a ubiquitous air pollutant, is the leading environmental risk factor for mortality worldwide. Experimental and epidemiological studies consistently suggest a strong link between long-term exposure to PM_2.5 (<2.5 μm, fine PM) and cognitive impairment. The neuroinflammatory response is presumed to be one of the main mechanisms of PM_2.5-induced cognitive impairment, possibly leading to synaptic dysfunction. However, the main route and mechanism underlying the cause of cognitive dysfunction and pathogenic alterations in PM_2.5-exposure mice remain poorly understood. Therefore, this study aimed to investigate the main route and mechanism of PM_2.5-induced cognitive impairment. Our results showed that PM_2.5 directly entered the brain following nasal administration, and both the short-term PM_2.5 administration via atomization and nasal drops induced learning and memory impairments and neuronal damage in adult mice. Moreover, astrocytes and microglia were both activated in the two short-term PM_2.5 exposure models, while few changes in the inflammatory response were observed in the peripheral circulatory system. Furthermore, a further transcriptional analysis revealed that short-term PM_2.5 administration led to cognitive impairment mainly by modulating synaptic functions and that although glia were activated, the glia-related pathological pathways were not significantly activated. Notably, following PM_2.5 exposure, PLX3397-induced microglial deletion did not restore the cognitive function of the mice. In conclusion, our results provide evidence that PM_2.5 enters the brain via the nose-to-brain route to impair cognitive function, and short-term exposure to PM_2.5 directly alters synaptic function rather than the neuroinflammatory response to affect cognition.

Effect of subchronic exposure to ambient fine and ultrafine particles on rat motor activity and ex vivo striatal dopaminergic transmission

Alterations in dopaminergic transmission are associated with neurological disorders, such as depression, autism, and Parkinson's disease. Exposure of rats to ambient fine (FP) or ultrafine (UFP) particles induces oxidative and inflammatory responses in the striatum, a neuronal nucleus with dense dopaminergic innervation and critically involved in the control of motor activity.Objectives: We used an ex vivo system to evaluate the effect of in vivo inhalation exposure to FP and UFP on motor activity and dopaminergic transmission.Materials and Methods: Male adult Wistar rats were exposed to FP, UFP, or filtered air for 8 weeks (subchronic exposure; 5 h/day, 5 days/week) in a particle concentrator. Motor activity was evaluated using the open-field test. Uptake and release of [³H]-dopamine were assessed in striatal synaptosomes, and dopamine D₂ receptor (D₂R) affinity for dopamine was evaluated by the displacement of [³H]-spiperone binding to striatal membranes.Results: Exposure to FP or UFP significantly reduced spontaneous motor activity (ambulatory distance: FP -25%, UFP -32%; ambulatory time: FP -24%, UFP -22%; ambulatory episodes: FP -22%, UFP -30%), decreased [³H]-dopamine uptake (FP -18%, UFP -24%), and increased, although not significantly, [³H]-dopamine release (113.3 ± 16.3 and 138.6 ± 17.3%). Neither FP nor UFP exposure affected D₂R density or affinity for dopamine.Conclusions: These results indicate that exposure to ambient particulate matter reduces locomotion in rats, which could be related to altered striatal dopaminergic transmission: UFP was more potent than FP. Our results contribute to the evidence linking environmental factors to changes in brain function that could turn into neurological and psychiatric disorders.HIGHLIGHTSYoung adult rats were exposed to fine (FP) or ultrafine (UFP) particles for 40 days.Exposure to FP or UFP reduced motor activity.Exposure to FP or UFP reduced dopamine uptake by striatal synaptosomes.Neither D₂R density or affinity for dopamine was affected by FP or UFP.UFP was more potent than FP to exert the effects reported.

Associations Between Ambient Air Pollution and Cognitive Abilities from Midlife to Early Old Age: Modification by APOE Genotype

BACKGROUND

Fine particulate matter (PM2.5) and nitrogen dioxide (NO2) measures of ambient air pollution are associated with accelerated age-related cognitive impairment, and Alzheimer's disease and related dementias (ADRD).

OBJECTIVE

We examined associations between air pollution, four cognitive factors, and the moderating role of apolipoprotein E (APOE) genotype in the understudied period of midlife.

METHODS

Participants were ∼1,100 men in the Vietnam Era Twin Study of Aging. Baseline cognitive assessments were from 2003 to 2007. Measures included past (1993-1999) and recent (3 years prior to baseline assessment) PM2.5 and NO2 exposure, in-person assessment of episodic memory, executive function, verbal fluency, and processing speed, and APOE genotype. Average baseline age was 56 years with a 12-year follow-up. Analyses adjusted for health and lifestyle covariates.

RESULTS

Performance in all cognitive domains declined from age 56 to 68. Higher PM2.5 exposures were associated with worse general verbal fluency. We found significant exposure-by-APOE genotype interactions for specific cognitive domains: PM2.5 with executive function and NO2 with episodic memory. Higher PM2.5 exposure was related to worse executive function in APOE ɛ4 carriers, but not in non-carriers. There were no associations with processing speed.

CONCLUSION

These results indicate negative effects of ambient air pollution exposure on fluency alongside intriguing differential modifications of cognitive performance by APOE genotype. APOE ɛ4 carriers appeared more sensitive to environmental differences. The process by which air pollution and its interaction with genetic risk for ADRD affects risk for later life cognitive decline or progression to dementia may begin in midlife.

Effects of prenatal exposure to PM2.5 and its composition on cognitive and motor functions in children at 12 months of age: The Shanghai Birth Cohort Study

BACKGROUND

Prenatal fine particulate matter (PM_2.5) exposure has been linked to infant cognitive and motor functions, but the effects of PM_2.5 chemical composition remain unclear.

OBJECTIVES

We aimed to explore the associations of prenatal PM_2.5 and its composition exposure with infant cognitive and motor functions.

METHODS

We studied 2,435 mother-infant pairs in the Shanghai Birth Cohort Study. PM_2.5 and its seven compositions [primary particles (black carbon, mineral dust and sea salts) and secondary particles (NH₄⁺, NO₃^-, SO₄^2- and organic matter)] during thethreetrimesters ofpregnancy were retrieved from the V4.CH.03 product developed by using a combined geoscience-statistical method. At the 12-month-old follow-up, infant cognitive and motor functions in five domains were assessed using the Ages and Stages Questionnaire (ASQ). We used multivariable linear regressions to estimate the effects of PM_2.5 and its composition on the ASQ scores, for all infants and stratifying by sex and breastfeeding duration.

RESULTS

PM_2.5 exposure was negatively associated with gross motor, problem-solving and personal-social scores for all infants. PM_2.5 compositions were inversely associated with ASQ scores in all five domains, and the effects of different compositions varied across domains. Specifically, all compositions except organic matter were correlated with lower problem-solving scores [e.g., ( [Formula: see text]  =  - 10.79, 95 % CI: -17.40, -4.18) ∼ ( [Formula: see text]  =  - 4.68, 95 % CI: -7.84, -1.53); for each 10 μg/m³ increase in PM_2.5 compositions during the third trimester]. Primary and some secondary particles (organic matter, NO₃^-) were related to lower gross motor scores. Secondary particles were also inversely associated with communication (organic matter and NO₃^-), fine motor (NH₄⁺, NO₃^-, SO₄^2-) and personal-social (NH₄⁺) scores. Additionally, boys and infants breastfed for < 6 months appeared to be more susceptible.

CONCLUSIONS

We found negative associations of PM_2.5 and its compositions with infant cognitive and motor functions over a range of domains, especially the problem-solving domain.

Air pollution, depressive and anxiety disorders, and brain effects: A systematic review

Accumulating data suggest that air pollution increases the risk of internalizing psychopathology, including anxiety and depressive disorders. Moreover, the link between air pollution and poor mental health may relate to neurostructural and neurofunctional changes. We systematically reviewed the MEDLINE database in September 2021 for original articles reporting effects of air pollution on 1) internalizing symptoms and behaviors (anxiety or depression) and 2) frontolimbic brain regions (i.e., hippocampus, amygdala, prefrontal cortex). One hundred and eleven articles on mental health (76% human, 24% animals) and 92 on brain structure and function (11% human, 86% animals) were identified. For literature search 1, the most common pollutants examined were PM2.5 (64.9%), NO2 (37.8%), and PM10 (33.3%). For literature search 2, the most common pollutants examined were PM2.5 (32.6%), O3 (26.1%) and Diesel Exhaust Particles (DEP) (26.1%). The majority of studies (73%) reported higher internalizing symptoms and behaviors with higher air pollution exposure. Air pollution was consistently associated (95% of articles reported significant findings) with neurostructural and neurofunctional effects (e.g., increased inflammation and oxidative stress, changes to neurotransmitters and neuromodulators and their metabolites) within multiple brain regions (24% of articles), or within the hippocampus (66%), PFC (7%), and amygdala (1%). For both literature searches, the most studied exposure time frames were adulthood (48% and 59% for literature searches 1 and 2, respectively) and the prenatal period (26% and 27% for literature searches 1 and 2, respectively). Forty-three percent and 29% of studies assessed more than one exposure window in literature search 1 and 2, respectively. The extant literature suggests that air pollution is associated with increased depressive and anxiety symptoms and behaviors, and alterations in brain regions implicated in risk of psychopathology. However, there are several gaps in the literature, including: limited studies examining the neural consequences of air pollution in humans. Further, a comprehensive developmental approach is needed to examine windows of susceptibility to exposure and track the emergence of psychopathology following air pollution exposure.

Influence of Impurities from Manufacturing Process on the Toxicity Profile of Boron Nitride Nanotubes

The toxicity of boron nitride nanotubes (BNNTs) has been the subject of conflicting reports, likely due to differences in the residuals and impurities that can make up to 30-60% of the material produced based on the manufacturing processes and purification employed. Four BNNTs manufactured by induction thermal plasma process with a gradient of BNNT purity levels achieved through sequential gas purification, water and solvent washing, allowed assessing the influence of these residuals/impurities on the toxicity profile of BNNTs. Extensive characterization including infrared and X-ray spectroscopy, thermogravimetric analysis, size, charge, surface area, and density captured the alteration in physicochemical properties as the material went through sequential purification. The material from each step is screened using acellular and in vitro assays for evaluating general toxicity, mechanisms of toxicity, and macrophage function. As the material increased in purity, there are more high-aspect-ratio particulates and a corresponding distinct increase in cytotoxicity, nuclear factor-κB transcription, and inflammasome activation. There is no alteration in macrophage function after BNNT exposure with all purity grades. The cytotoxicity and mechanism of screening clustered with the purity grade of BNNTs, illustrating that greater purity of BNNT corresponds to greater toxicity.

A comprehensive understanding of ambient particulate matter and its components on the adverse health effects based from epidemiological and laboratory evidence

The impacts of air pollution on public health have become a great concern worldwide. Ambient particulate matter (PM) is a major air pollution that comprises a heterogeneous mixture of different particle sizes and chemical components. The chemical composition and physicochemical properties of PM change with space and time, which may cause different impairments. However, the mechanisms of the adverse effects of PM on various systems have not been fully elucidated and systematically integrated. The Adverse Outcome Pathway (AOP) framework was used to comprehensively illustrate the molecular mechanism of adverse effects of PM and its components, so as to clarify the causal mechanistic relationships of PM-triggered toxicity on various systems. The main conclusions and new insights of the correlation between public health and PM were discussed, especially at low concentrations, which points out the direction for further research in the future. With the deepening of the study on its toxicity mechanism, it was found that PM can still induce adverse health effects with low-dose exposure. And the recommended Air Quality Guideline level of PM_2.5 was adjusted to 5 μg/m³ by World Health Organization, which meant that deeper and more complex mechanisms needed to be explored. Traditionally, oxidative stress, inflammation, autophagy and apoptosis were considered the main mechanisms of harmful effects of PM. However, recent studies have identified several emerging mechanisms involved in the toxicity of PM, including pyroptosis, ferroptosis and epigenetic modifications. This review summarized the comprehensive evidence on the health effects of PM and the chemical components of it, as well as the combined toxicity of PM with other air pollutants. Based on the AOP Wiki and the mechanisms of PM-induced toxicity at different levels, we first constructed the PM-related AOP frameworks on various systems.

Prenatal fine particulate matter exposure associated with placental small extracellular vesicle derived microRNA and child neurodevelopmental delays

BACKGROUND AND AIMS

Prenatal fine particulate matter (PM_2.5) exposure has been linked to adverse neurodevelopment. However, epidemiological evidence remains inconclusive and little information about the effects of various PM_2.5 components on child neurodevelopment is currently known. The underlying mechanism was also not elucidated. The study aimed to evaluate the effects of PM_2.5 and components exposure on child neurodevelopmental delays and the role of placental small extracellular vesicles (sEVs)-derived miRNAs in the associations.

METHODS

We included 267 mother-child pairs in this analysis. Prenatal PM_2.5 and components (i.e. elements, water-soluble ions, and PAHs) exposure during three trimesters were monitored through personal PM_2.5 sampling. Child neurodevelopment at 2, 6, and 12 months old were evaluated by Ages and Stages Questionnaire (ASQ). We isolated sEVs from placental tissue to analyze the change of sEVs-derived miRNAs in response to PM_2.5. Associations between the PM_2.5-associated miRNAs and child neurodevelopment were evaluated using multivariate linear regression models.

RESULTS

The PM_2.5 exposure levels in the three trimesters range from 2.51 to 185.21 μg/m³. Prenatal PM_2.5 and the components of Pb, Al, V and Ti exposure in the second and third trimester were related to decreased ASQ scores communication, problem-solving and personal-social domains in children aged 2 or 6 months. RNA sequencing identified fifteen differentially expressed miRNAs. The miR-101-3p and miR-520d-5p were negatively associated with PM_2.5 and Pb component. miR-320a-3p expression was positively associated with PM_2.5 and V component. Meanwhile, the miR-320a-3p was associated with decreased ASQ scores, as reflected by ASQ-T (β: -2.154, 95 % CI: -4.313, -0.516) and problem-solving domain (β: -0.605, 95 % CI: -1.111, -0.099) in children aged 6 months.

CONCLUSION

Prenatal exposure to PM_2.5 and its Pb, Al, V & Ti component were associated with infant neurodevelopmental delays. The placenta sEVs derived miRNAs, especially miR-320a-3p, might contribute to an increased risk of neurodevelopmental delays.

Evaluation of In Vitro Cytotoxic, Genotoxic, Apoptotic, and Cell Cycle Arrest Potential of Iron-Nickel Alloy Nanoparticles

The use of iron-nickel alloy nanoparticles (Fe-Ni ANPs) is increasing daily in various fields. People are increasingly exposed to these nanoparticles for occupational and environmental reasons. Our study determined some of the effects of Fe-Ni ANP exposure and impacts on human health at the cellular level. The cytotoxic and genotoxic potentials of Fe-Ni ANPs were investigated by XTT, clonogenic, comet, and GammaH2AX analyses using Beas-2B cells. Annexin V, multicaspase, and cell cycle arrest methods were used to understand the apoptotic mechanism of action. The intracellular ROS method was used to determine the primary mechanism that leads to cytotoxic and genotoxic activity. The Fe-Ni ANPs showed cytotoxic activity with the XTT and clonogenic methods: they had genotoxic potential, as demonstrated via genotoxicity methods. It was determined that the cytotoxic effect was realized by the caspase-dependent apoptotic pathway, and the cells were stopped at the G0/G1 stage by Fe-Ni ANPs. Increased intracellular ROS due to Fe-Ni ANPs led to cytotoxic, genotoxic, and apoptotic activity. Potential risks to human health due to Fe-Ni ANPs were then demonstrated at the cellular level.

Neurotoxicity of Diesel Exhaust Particles

BACKGROUND

Air pollution particulate matter (PM) is strongly associated with risks of accelerated cognitive decline, dementia and Alzheimer's disease. Ambient PM batches have variable neurotoxicity by collection site and season, which limits replicability of findings within and between research groups for analysis of mechanisms and interventions. Diesel exhaust particles (DEP) offer a replicable model that we define in further detail.

OBJECTIVE

Define dose- and time course neurotoxic responses of mice to DEP from the National Institute of Science and Technology (NIST) for neurotoxic responses shared by DEP and ambient PM.

METHODS

For dose-response, adult C57BL/6 male mice were exposed to 0, 25, 50, and 100μg/m3 of re-aerosolized DEP (NIST SRM 2975) for 5 h. Then, mice were exposed to 100μg/m3 DEP for 5, 100, and 200 h and assayed for amyloid-β peptides, inflammation, oxidative damage, and microglial activity and morphology.

RESULTS

DEP exposure at 100μg/m3 for 5 h, but not lower doses, caused oxidative damage, complement and microglia activation in cerebral cortex and corpus callosum. Longer DEP exposure for 8 weeks/200 h caused further oxidative damage, increased soluble Aβ, white matter injury, and microglial soma enlargement that differed by cortical layer.

CONCLUSION

Exposure to 100μg/m3 DEP NIST SRM 2975 caused robust neurotoxic responses that are shared with prior studies using DEP or ambient PM0.2. DEP provides a replicable model to study neurotoxic mechanisms of ambient PM and interventions relevant to cognitive decline and dementia.

Lung-Based, Exosome Inhibition Mediates Systemic Impacts Following Particulate Matter Exposure

Particulate matter (PM) exposure is a global health issue that impacts both urban and rural communities. Residential communities in the Southwestern United States have expressed concerns regarding the health impacts of fugitive PM from rural, legacy mine-sites. In addition, the recent literature suggests that exosomes may play a role in driving toxicological phenotypes following inhaled exposures. In this study, we assessed exosome-driven mechanisms and systemic health impacts following inhaled dust exposure, using a rodent model. Using an exosome inhibitor, GW4869 (10 μM), we inhibited exosome generation in the lungs of mice via oropharyngeal aspiration. We then exposed mice to previously characterized inhaled particulate matter (PM) from a legacy mine-site and subsequently assessed downstream behavioral, cellular, and molecular biomarkers in lung, serum, and brain tissue. Results indicated that CCL-2 was significantly upregulated in the lung tissue and downregulated in the brain (p < 0.05) following PM exposure. Additional experiments revealed cerebrovascular barrier integrity deficits and increased glial fibrillary acidic protein (GFAP) staining in the mine-PM exposure group, mechanistically dependent on exosome inhibition. An increased stress and anxiety response, based on the open-field test, was noted in the mine-PM exposure group, and subsequently mitigated with GW4869 intervention. Exosome lipidomics revealed 240 and eight significantly altered positive-ion lipids and negative-ion lipids, respectively, across the three treatment groups. Generally, phosphatidylethanolamine (PE) and phosphatidylcholine (PC) lipids were significantly downregulated in the PM group, compared to FA. In conclusion, these data suggest that systemic, toxic impacts of inhaled PM may be mechanistically dependent on lung-derived, circulating exosomes, thereby driving a systemic, proinflammatory phenotype.

Neurotoxicity of Polycyclic Aromatic Hydrocarbons: A Systematic Mapping and Review of Neuropathological Mechanisms

Several studies present the neurotoxic effects of polycyclic aromatic hydrocarbons (PAHs), a class of environmental pollutants capable of causing neurological deficits. However, a collective review approach to this research topic is scarce. This study presents the effect of PAHs on the central nervous system using a bibliometric approach. The neuropathological mechanisms of PAHs are also highlighted. Published articles were searched for in the Scopus and Web of Science databases from January 1979 to December 2020 using the keywords ‘polycyclic aromatic hydrocarbons’ and ‘neurotoxicity’. The total number of documents retrieved from both databases was 338. Duplicated documents (80) were excluded and 258 articles were used for the final analysis. Our findings revealed that there has been a significant increase in research outputs on this topic in the last ten years. The countries with the highest scientific productivity in this area are USA, China, France and Italy. The result also showed that, in the past few years, global scientific output in research relating to PAH neurotoxicity focused on neurodegeneration, cholinergic function, neurodevelopmental toxicity, behavioural studies, oxidative stress, neuroprotection and therapeutic intervention using different experimental models, including zebrafish, neuronal cell lines, Caenorhabditis elegans and rats. Recent studies also revealed the neuroprotective roles of some natural products against PAH-induced neurotoxicity. However, more investigation involving clinical trials is required to emphasize the observed neurotoxic effects.

The Effects of Indoor Air Filter on Reductions in PM2.5 Associated Health Risks of Respiratory Function in Mouse

This study aimed to assess whether protective measures could reduce the health risks of air pollution in mice living in the chambers situated at a suburban site in Beijing. The living chambers of mice were divided into four groups: male mice with and without the high-efficiency particulate air (HEPA) filter (male group A and group B), as well as female mice with and without the HEPA filter (female group A and group B). The experiment was carried out from 1 December 2017 to 31 May 2018. Parameters of respiratory function during periods of clean air and air pollution were determined for all groups to evaluate the role of the indoor air filter (i.e., HEPA) in protection against respiratory health risks in mice. Significant differences in minute volumes were observed in male and female groups with versus without the HEPA. Additionally, respiratory health parameters including respiratory rate, duration of breaking, expiratory time, and relaxation time exhibited differences in female groups with HEPA versus without HEPA. Levels of inflammatory factors in the lungs were measured for all groups after 6months of exposure. Greater mean levels of IL-6 and TNF-α were found in the male groups without HEPA than in those with HEPA. Higher average concentrations of IL-6, T-AOC, SOD, GSH-Px, LDH, TNF-α, and TGF-β1 were found in the female group without HEPA than those without HEPA. Our study has proved the effective protection provided by indoor air filters (i.e., HEPA filters) in reducing respiratory health risks associated with PM2.5.

TUBE Project: Transport-Derived Ultrafines and the Brain Effects

The adverse effects of air pollutants on the respiratory and cardiovascular systems are unquestionable. However, in recent years, indications of effects beyond these organ systems have become more evident. Traffic-related air pollution has been linked with neurological diseases, exacerbated cognitive dysfunction, and Alzheimer's disease. However, the exact air pollutant compositions and exposure scenarios leading to these adverse health effects are not known. Although several components of air pollution may be at play, recent experimental studies point to a key role of ultrafine particles (UFPs). While the importance of UFPs has been recognized, almost nothing is known about the smallest fraction of UFPs, and only >23 nm emissions are regulated in the EU. Moreover, the role of the semivolatile fraction of the emissions has been neglected. The Transport-Derived Ultrafines and the Brain Effects (TUBE) project will increase knowledge on harmful ultrafine air pollutants, as well as semivolatile compounds related to adverse health effects. By including all the major current combustion and emission control technologies, the TUBE project aims to provide new information on the adverse health effects of current traffic, as well as information for decision makers to develop more effective emission legislation. Most importantly, the TUBE project will include adverse health effects beyond the respiratory system; TUBE will assess how air pollution affects the brain and how air pollution particles might be removed from the brain. The purpose of this report is to describe the TUBE project, its background, and its goals.

An Air Particulate Pollutant Induces Neuroinflammation and Neurodegeneration in Human Brain Models

Fine particulate matter (PM2.5), a major component among air pollutants, highlights as a global health concern. Several epidemiological studies show the correlation between chronical PM2.5 exposure and incidents of neurological disorders including Alzheimer's disease. However, the mechanisms have not been well understood, partly due to the lack of model systems that reflect the physiologically relevant innate immunity in human brains. Here, PM2.5-polluted human brain models (PMBs) are created in a 3D microfluidic platform reconstituting key aspects of human brain immunity under the PM2.5 exposure. PM2.5 penetration across a blood-brain barrier (BBB) model and accumulation in the brain tissue side of the model are first validated. Second, the PMB model shows that the BBB-penetrating PM2.5 initiates astrogliosis, resulting in slight neuronal loss and microglial infiltration. Third, it is demonstrated that the infiltrating microglia obtain M1 phenotype induced by interleukin-1β and interferon-γ from neurons and reactive astrocytes under the PM2.5 exposure. Finally, it is observed that additional proinflammatory mediators and nitric oxide released from the M1 microglia exacerbate neuronal damages, such as synaptic impairment, phosphoric tau accumulation, and neuronal death. This study suggests that PM2.5 can be a potential environmental risk factor for dementia mediated by the detrimental neuroinflammation.

Gene-Environment Interactions and Stochastic Variations in the Gero-Exposome

The limited heritability of human life spans suggests an important role for gene-environment (G × E) interactions across the life span (T), from gametes to geronts. Multilevel G × E × T interactions of aging phenotypes are conceptualized in the Gero-Exposome as Exogenous and Endogenous domains. Stochastic variations in the Endogenous domain contribute to the diversity of aging phenotypes, shown for the diversity of inbred Caenorhabditis elegans life spans in the same culture environment, and for variegated gene expression of somatic cells in nematodes and mammals. These phenotypic complexities can be analyzed as 3-way interactions of gene, environment, and stochastic variations, the Tripartite Phenotype of Aging. Single-cell analyses provide tools to explore this broadening frontier of biogerontology.

Cerebral cortex and blood transcriptome changes in mouse neonates prenatally exposed to air pollution particulate matter

Background

Prenatal exposure to air pollutants is associated with increased risk for neurodevelopmental and neurodegenerative disorders. However, few studies have identified transcriptional changes related to air pollutant exposure.

Methods

RNA sequencing was used to examine transcriptomic changes in blood and cerebral cortex of three male and three female mouse neonates prenatally exposed to traffic-related nano-sized particulate matter (nPM) compared to three male and three female mouse neonates prenatally exposed to control filter air.

Results

We identified 19 nPM-associated differentially expressed genes (nPM-DEGs) in blood and 124 nPM-DEGs in cerebral cortex. The cerebral cortex transcriptional responses to nPM suggested neuroinflammation involvement, including CREB1, BDNF, and IFNγ genes. Both blood and brain tissues showed nPM transcriptional changes related to DNA damage, oxidative stress, and immune responses. Three blood nPM-DEGs showed a canonical correlation of 0.98 with 14 nPM-DEGS in the cerebral cortex, suggesting a convergence of gene expression changes in blood and cerebral cortex. Exploratory sex-stratified analyses suggested a higher number of nPM-DEGs in female cerebral cortex than male cerebral cortex. The sex-stratified analyses identified 2 nPM-DEGs (Rgl2 and Gm37534) shared between blood and cerebral cortex in a sex-dependent manner.

Conclusions

Our findings suggest that prenatal nPM exposure induces transcriptional changes in the cerebral cortex, some of which are also observed in blood. Further research is needed to replicate nPM-induced transcriptional changes with additional biologically relevant time points for brain development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-021-09380-3.

Metal and metal(loids) removal efficiency using genetically engineered microbes: Applications and challenges

The environment is being polluted in different many with metal and metalloid pollution, mostly due to anthropogenic activity, which is directly affecting human and environmental health. Metals and metalloids are highly toxic at low concentrations and contribute primarily to the survival equilibrium of activities in the environment. However, because of non-degradable, they persist in nature and these metal and metalloids bioaccumulate in the food chain. Genetically engineered microorganisms (GEMs) mediated techniques for the removal of metals and metalloids are considered an environmentally safe and economically feasible strategy. Various forms of GEMs, including fungi, algae, and bacteria have been produced by recombinant DNA and RNA technologies, which have been used to eliminate metal and metalloids compounds from the polluted areas. Besides, GEMs have the potentiality to produce enzymes and other metabolites that are capable of tolerating metals stress and detoxify the pollutants. Thus, the aim of this review is to discuss the use of GEMs as advanced tools to produce metabolites, signaling molecules, proteins through genetic expression during metal and metalloids interaction, which help in the breakdown of persistent pollutants in the environment.

Suppressive Effects of Rosmarinic Acid Rich Fraction from Perilla on Oxidative Stress, Inflammation and Metastasis Ability in A549 Cells Exposed to PM via C-Jun, P-65-Nf-Κb and Akt Signaling Pathways

Particulate matter from forest fires (PMFF) is an environmental pollutant causing oxidative stress, inflammation, and cancer cell metastasis due to the presence of polycyclic aromatic hydrocarbons (PAHs). Perilla seed meal contains high levels of polyphenols, including rosmarinic acid (RA). The aim of this study is to determine the anti-oxidative stress, anti-inflammation, and anti-metastasis actions of rosmarinic acid rich fraction (RA-RF) from perilla seed meal and its underlying molecular mechanisms in A549 cells exposed to PMFF. PMFF samples were collected via the air sampler at the University of Phayao, Thailand, and their PAH content were analyzed using GC-MS. Fifteen PAH compounds were detected in PMFF. The PMFF significantly induced intracellular reactive oxygen species (ROS) production, the mRNA expression of pro-inflammatory cytokines, MMP-9 activity, invasion, migration, the overexpression of c-Jun and p-65-NF-κB, and Akt phosphorylation. Additionally, the RA-RF significantly reduced ROS production, IL-6, IL-8, TNF-α, and COX-2. RA-RF could also suppress MMP-9 activity, migration, invasion, and the phosphorylation activity of c-Jun, p-65-NF-κB, and Akt. Our findings revealed that RA-RF has antioxidant, anti-inflammatory, and anti-metastasis properties via c-Jun, p-65-NF-κB, and Akt signaling pathways. RA-RF may be further developed as an inhalation agent for the prevention of lung inflammation and cancer metastasis induced by PM exposure.

Exposure to low-dose ambient fine particulate matter PM2.5 and Alzheimer's disease, non-Alzheimer's dementia, and Parkinson's disease in North Carolina

Alzheimer's disease (AD), non-AD dementia, and Parkinson's disease (PD) are increasingly common in older adults, yet all risk factors for their onset are not fully understood. Consequently, environmental exposures, including air pollution, have been hypothesized to contribute to the etiology of neurodegeneration. Because persistently elevated rates of AD mortality in the southern Piedmont area of North Carolina (NC) have been documented, we studied mortality and hospital admissions for AD, non-AD dementia, and PD in residential populations aged 65+ with long-term exposures to elevated levels of ambient air particulate matter 2.5 (PM2.5) exceeding the World Health Organization (WHO) air quality standards (≥10μg/m3). Health data were obtained from the State Center for Health Statistics and the Healthcare Cost and Utilization Project. PM2.5 levels were obtained from the MODIS/MISR and SeaWiFS datafiles. Residents in the Study group of elevated air particulate matter (87 zip codes with PM2.5≥10μg/m3) were compared to the residents in the Control group with low levels of air particulate matter (81 zip codes with PM2.5≤7.61μg/m3), and were found to have higher age-adjusted rates of mortality and hospital admissions for AD, non-AD dementia, and PD, including a most pronounced increase in AD mortality (323/100,000 vs. 257/100,000, respectively). After adjustment for multiple co-factors, the risk of death (odds ratio, or OR) from AD in the Study group (OR = 1.35, 95%CI[1.24-1.48]) was significantly higher than ORs of non-AD dementia or PD (OR = 0.97, 95%CI[0.90-1.04] and OR = 1.13, 95%CI[0.92-1.31]). The OR of hospital admissions was significantly increased only for AD as a primary case of hospitalization (OR = 1.54, 95%CI[1.31-1.82]). Conclusion: NC residents aged 65+ with long-term exposures to ambient PM2.5 levels exceeding the WHO standard had significantly increased risks of death and hospital admissions for AD. The effects for non-AD dementia and PD were less pronounced.

Particulate Air Pollution and Osteoporosis: A Systematic Review

Air pollution is associated with inflammation and oxidative stress, which predispose to several chronic diseases in human. Emerging evidence suggests that the severity and progression of osteoporosis are directly associated with inflammation induced by air pollutants like particulate matter (PM). This systematic review examined the relationship between PM and bone health or fractures. A comprehensive literature search was conducted from January until February 2021 using the PubMed, Scopus, Web of Science, Google Scholar and Cochrane Library databases. Human cross-sectional, cohort and case-control studies were considered. Of the 1500 papers identified, 14 articles were included based on the inclusion and exclusion criteria. The air pollution index investigated by most studies were PM2.5 and PM10. Current studies demonstrated inconsistent associations between PM and osteoporosis risk or fractures, which may partly due to the heterogeneity in subjects' characteristics, study design and analysis. In conclusion, there is an inconclusive relationship between osteoporosis risk and fracture and PM exposures which require further validation.

A review of human and animals exposure to polycyclic aromatic hydrocarbons: Health risk and adverse effects, photo-induced toxicity and regulating effect of microplastics

Polycyclic aromatic hydrocarbons (PAHs) are one of the most widely distributed persistent organic pollutants (POPs) in the environmental media. PAHs have been widely concerned due to their significant health risk and adverse effects to human and animals. Currently, the main sources of PAHs in the environment are the incomplete combustion of fossil fuels, as well as municipal waste incineration and agricultural non-surface source emissions. In this work, the scope of our attention includes 16 typical PAHs themselves without involving their metabolites and industrial by-products. Exposure of human and animals to PAHs can lead to a variety of adverse effects, including carcinogenicity and teratogenicity, genotoxicity, reproductive- and endocrine-disrupting effects, immunotoxicity and neurotoxicity, the type and severity of which depend on a variety of factors. On the other hand, the regulatory effect of microplastics (MPs) on the bio-toxicity and bioaccumulation capacity of PAHs has now gradually attracted attention. We critically reviewed the adsorption capacity and mechanisms of MPs on PAHs as well as the effects of MPs on PAHs toxicity, thus highlighting the importance of paying attention to the joint bio-toxicity caused by PAHs-MPs interactions. In addition, due to the extensive nature of the common exposure pathway of PAHs and ultraviolet ray, an accurate understanding of biological processes exposed to both PAHs and UV light is necessary to develop effective protective strategies. Finally, based on the above critical review, we highlighted the research gaps and pointed out the priority of further studies.

Air Pollution Neurotoxicity in the Adult Brain: Emerging Concepts from Experimental Findings

Epidemiological studies are associating elevated exposure to air pollution with increased risk of Alzheimer's disease and other neurodegenerative disorders. In effect, air pollution accelerates many aging conditions that promote cognitive declines of aging. The underlying mechanisms and scale of effects remain largely unknown due to its chemical and physical complexity. Moreover, individual responses to air pollution are shaped by an intricate interface of pollutant mixture with the biological features of the exposed individual such as age, sex, genetic background, underlying diseases, and nutrition, but also other environmental factors including exposure to cigarette smoke. Resolving this complex manifold requires more detailed environmental and lifestyle data on diverse populations, and a systematic experimental approach. Our review aims to summarize the modest existing literature on experimental studies on air pollution neurotoxicity for adult rodents and identify key gaps and emerging challenges as we go forward. It is timely for experimental biologists to critically understand prior findings and develop innovative approaches to this urgent global problem. We hope to increase recognition of the importance of air pollution on brain aging by our colleagues in the neurosciences and in biomedical gerontology, and to support the immediate translation of the findings into public health guidelines for the regulation of remedial environmental factors that accelerate aging processes.

Aquatic toxicity of particulate matter emitted by five electroplating processes in two marine microalgae species

Electroplating is a widely used group of industrial processes that make a metal coating on a solid substrate. Our previous research studied the concentrations, characteristics, and chemical composition of nano- and microparticles emitted during different electroplating processes. The objective of this study was to evaluate the environmental toxicity of particulate matter obtained from five different electrochemical processes. We collected airborne particle samples formed during aluminum cleaning, aluminum etching, chemical degreasing, nonferrous metals etching, and nickel plating. The toxicity of the particles was evaluated by the standard microalgae growth rate inhibition test. Additionally, we evaluated membrane potential and cell size changes in the microalgae H. akashiwo and P. purpureum exposed to the obtained suspensions of electroplating particles. The findings of this research demonstrate that the aquatic toxicity of electroplating emissions significantly varies between different industrial processes and mostly depends on particle chemical composition and solubility rather than the number of insoluble particles. The sample from an aluminum cleaning workshop was significantly more toxic for both microalgae species compared to the other samples and demonstrated dose and time-dependent toxicity. The samples obtained during chemical degreasing and nonferrous metals etching processes induced depolarization of microalgal cell membranes, demonstrated the potential of chronic toxicity, and stimulated the growth rate of microalgae after 72 h of exposure. Moreover, the sample from a nonferrous metals etching workshop revealed hormetic dose-response toxicity in H. akashiwo, which can lead to harmful algal blooms in the environment.

Early life exposure to air pollution impacts neuronal and glial cell function leading to impaired neurodevelopment

The World Health Organisation recently listed air pollution as the most significant threat to human health. Air pollution comprises particulate matter (PM), metals, black carbon and gases such as ozone (O₃ ), nitrogen dioxide (NO₂ ) and carbon monoxide (CO). In addition to respiratory and cardiovascular disease, PM exposure is linked with increased risk of neurodegeneration as well as neurodevelopmental impairments. Critically, studies suggest that PM crosses the placenta, making direct in utero exposure a reality. Rodent models reveal that neuroinflammation, neurotransmitter imbalance and oxidative stress are triggered following gestational/early life exposure to PM, and may be exacerbated by concomitant mitochondrial dysfunction. Gestational PM exposure (potentiated by mitochondrial impairment in the metabolically active neonatal brain) not only impacts neurodevelopment but may sensitise the brain to subsequent cognitive impairment. Having reviewed this field, we conclude that strategies are urgently required to reduce exposure to PM during this sensitive developmental period.

Integrated RNA Sequencing Reveals Epigenetic Impacts of Diesel Particulate Matter Exposure in Human Cerebral Organoids

Autism spectrum disorder (ASD) manifests early in childhood. While genetic variants increase risk for ASD, a growing body of literature has established that in utero chemical exposures also contribute to ASD risk. These chemicals include air-based pollutants like diesel particulate matter (DPM). A combination of single-cell and direct transcriptomics of DPM-exposed human-induced pluripotent stem cell-derived cerebral organoids revealed toxicogenomic effects of DPM exposure during fetal brain development. Direct transcriptomics, sequencing RNA bases via Nanopore, revealed that cerebral organoids contain extensive RNA modifications, with DPM-altering cytosine methylation in oxidative mitochondrial transcripts expressed in outer radial glia cells. Single-cell transcriptomics further confirmed an oxidative phosphorylation change in cell groups such as outer radial glia upon DPM exposure. This approach highlights how DPM exposure perturbs normal mitochondrial function and cellular respiration during early brain development, which may contribute to developmental disorders like ASD by altering neurodevelopment.

Variations in Reactive Oxygen Species Generation by Urban Airborne Particulate Matter in Lung Epithelial Cells-Impact of Inorganic Fraction

Air pollution is associated with numerous negative effects on human health. The toxicity of organic components of air pollution is well-recognized, while the impact of their inorganic counterparts in the overall toxicity is still a matter of various discussions. The influence of airborne particulate matter (PM) and their inorganic components on biological function of human alveolar-like epithelial cells (A549) was investigated in vitro. A novel treatment protocol based on covering culture plates with PM allowed increasing the studied pollutant concentrations and prolonging their incubation time without cell exposure on physical suffocation and mechanical disturbance. PM decreased the viability of A549 cells and disrupted their mitochondrial membrane potential and calcium homeostasis. For the first time, the difference in the reactive oxygen species (ROS) profiles generated by organic and inorganic counterparts of PM was shown. Singlet oxygen generation was observed only after treatment of cells with inorganic fraction of PM, while hydrogen peroxide, hydroxyl radical, and superoxide anion radical were induced after exposure of A549 cells to both PM and their inorganic fraction.

Developmental Exposure to Air Pollution, Cigarettes, and Lead: Implications for Brain Aging

Brain development is impaired by maternal exposure to airborne toxins from ambient air pollution, cigarette smoke, and lead. Shared postnatal consequences include gray matter deficits and abnormal behaviors as well as elevated blood pressure. These unexpectedly broad convergences have implications for later life brain health because these same airborne toxins accelerate brain aging. Gene-environment interactions are shown for ApoE alleles that influence the risk of Alzheimer disease. The multigenerational trace of these toxins extends before fertilization because egg cells are formed in the grandmaternal uterus. The lineage and sex-specific effects of grandmaternal exposure to lead and cigarettes indicate epigenetic processes of relevance to future generations from our current and recent exposure to airborne toxins.

The APOE gene cluster responds to air pollution factors in mice with coordinated expression of genes that differs by age in humans

Little is known of gene-environment interactions for Alzheimer's disease (AD) risk factors. Apolipoprotein E (APOE) and neighbors on chromosome 19q13.3 have variants associated with risks of AD, but with unknown mechanism. This study describes novel links among the APOE network, air pollution, and age-related diseases. Mice exposed to air pollution nano-sized particulate matter (nPM) had coordinate responses of Apoe-Apoc1-Tomm40 in the cerebral cortex. In humans, the AD vulnerable hippocampus and amygdala had stronger age decline in APOE cluster expression than the AD-resistant cerebellum and hypothalamus. Using consensus weighted gene co-expression network, we showed that APOE has a conserved co-expressed network in rodent and primate brains. SOX1, which has AD-associated single nucleotide polymorphisms, was among the co-expressed genes in the human hippocampus. Humans and mice shared 87% of potential binding sites for transcription factors in APOE cluster promoter, suggesting similar inducibility and a novel link among environment, APOE cluster, and risk of AD.

In vitro exposure to ambient fine and ultrafine particles alters dopamine uptake and release, and D2 receptor affinity and signaling

The exposure to environmental pollutants, such as fine and ultrafine particles (FP and UFP), has been associated with increased risk for Parkinson's disease, depression and schizophrenia, disorders related to altered dopaminergic transmission. The striatum, a neuronal nucleus with extensive dopaminergic afferents, is a target site for particle toxicity, which results in oxidative stress, inflammation, astrocyte activation and modifications in dopamine content and D₂ receptor (D₂R) density. In this study we assessed the in vitro effect of the exposure to FP and UFP on dopaminergic transmission, by evaluating [³H]-dopamine uptake and release by rat striatal isolated nerve terminals (synaptosomes), as well as modifications in the affinity and signaling of native and cloned D₂Rs. FP and UFP collected from the air of Mexico City inhibited [³H]-dopamine uptake and increased depolarization-evoked [³H]-dopamine release in striatal synaptosomes. FP and UFP also enhanced D₂R affinity for dopamine in membranes from either rat striatum or CHO-K1 cells transfected with the long isoform of the human D₂R (hD_2LR)2LR). In CHO-K1-hD2L In CHO-K1-hD_2LR cells or striatal slices, FP and UFP increased the potency of dopamine or the D₂R agonist quinpirole, respectively, to inhibit forskolin-induced cAMP formation. The effects were concentration-dependent, with UFP being more potent than FP. These results indicate that FP and UFP directly affect dopaminergic transmission.

Environmental Epigenetics of Diesel Particulate Matter Toxicogenomics

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by disruptions in social communication and behavioral flexibility. Both genetic and environmental factors contribute to ASD risk. Epidemiologic studies indicate that roadway vehicle exhaust and in utero exposure to diesel particulate matter (DPM) are associated with ASD. Using the Comparative Toxicogenomics Database (CTD), we identified genes connected to DPM exposure and ASD, extracted the known enhancers/promoters of the identified genes, and integrated this with Assay for Transposase Accessible Chromatin (ATAC-seq) data from DPM-exposed human neural progenitor cells. Enhancer/promoter elements with significantly different chromosome accessibility revealed enriched DNA sequence motifs with transcription factor binding sites for EGR1. Variant extraction for linkage disequilibrium blocks of these regions followed by analysis through Genome Wide Association Studies (GWAS) revealed multiple neurological trait associations including exploratory eye movement and brain volume measurement. This approach highlights the effects of pollution on the regulatory regions of genes implicated in ASD by genetic studies, indicating convergence of genetic and environmental factors on molecular networks that contribute to ASD. Integration of publicly available data from the CTD, cell culture exposure studies, and phenotypic genetics synergize extensive evidence of chemical exposures on gene regulation for altered brain development.

Astaxanthin Suppresses PM2.5-Induced Neuroinflammation by Regulating Akt Phosphorylation in BV-2 Microglial Cells

Air pollution has become one of the most serious issues for human health and has been shown to be particularly concerning for neural and cognitive health. Recent studies suggest that fine particulate matter of less than 2.5 (PM2.5), common in air pollution, can reach the brain, potentially resulting in the development and acceleration of various neurological disorders including Alzheimer’s disease, Parkinson’s disease, and other forms of dementia, but the underlying pathological mechanisms are not clear. Astaxanthin is a red-colored phytonutrient carotenoid that has been known for anti-inflammatory and neuroprotective effects. In this study, we demonstrated that exposure to PM2.5 increases the neuroinflammation, the expression of proinflammatory M1, and disease-associated microglia (DAM) signature markers in microglial cells, and that treatment with astaxanthin can prevent the neurotoxic effects of this exposure through anti-inflammatory properties. Diesel particulate matter (Sigma-Aldrich) was used as a fine particulate matter 2.5 in the present study. Cultured rat glial cells and BV-2 microglial cells were treated with various concentrations of PM2.5, and then the expression of various inflammatory mediators and signaling pathways were measured using qRT-PCR and Western blot. Astaxanthin was then added and assayed as above to evaluate its effects on microglial changes, inflammation, and toxicity induced by PM2.5. PM2.5 increased the production of nitric oxide and reactive oxygen species and upregulated the transcription of various proinflammatory markers including Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Tumor necrosis factor α (TNFα), inducible nitric oxide synthase (iNOS), triggering receptor expressed on myeloid cells 2 (TREM2), Toll-like receptor 2/4 (TLR2/4), and cyclooxygenase-2 (COX-2) in BV-2 microglial cells. However, the mRNA expression of IL-10 and arginase-1 decreased following PM2.5 treatment. PM2.5 treatment increased c-Jun N-terminal kinases (JNK) phosphorylation and decreased Akt phosphorylation. Astaxanthin attenuated these PM2.5-induced responses, reducing transcription of the proinflammatory markers iNOS and heme oxygenase-1 (HO-1), which prevented neuronal cell death. Our results indicate that PM2.5 exposure reformulates microglia via proinflammatory M1 and DAM phenotype, leading to neurotoxicity, and the fact that astaxanthin treatment can prevent neurotoxicity by inhibiting transition to the proinflammatory M1 and DAM phenotypes. These results demonstrate that PM2.5 exposure can induce brain damage through the change of proinflammatory M1 and DAM signatures in the microglial cells, as well as the fact that astaxanthin can have a potential beneficial effect on PM2.5 exposure of the brain.

Adult mouse hippocampal transcriptome changes associated with long-term behavioral and metabolic effects of gestational air pollution toxicity

Gestational exposure to air pollution increases the risk of autism spectrum disorder and cognitive impairments with unresolved molecular mechanisms. This study exposed C57BL/6J mice throughout gestation to urban-derived nanosized particulate matter (nPM). Young adult male and female offspring were studied for behavioral and metabolic changes using forced swim test, fat gain, glucose tolerance, and hippocampal transcriptome. Gestational nPM exposure caused increased depressive behaviors, decreased neurogenesis in the dentate gyrus, and increased glucose tolerance in adult male offspring. Both sexes gained fat and body weight. Gestational nPM exposure induced 29 differentially expressed genes (DEGs) in adult hippocampus related to cytokine production, IL17a signaling, and dopamine degradation in both sexes. Stratification by sex showed twofold more DEGs in males than females (69 vs 37), as well as male-specific enrichment of DEGs mediating serotonin signaling, endocytosis, Gαi, and cAMP signaling. Gene co-expression analysis (WCGNA) identified a module of 43 genes with divergent responses to nPM between the sexes. Chronic changes in 14 DEGs (e.g., microRNA9-1) were associated with depressive behaviors, adiposity and glucose intolerance. These genes enriched neuroimmune pathways such as HMGB1 and TLR4. Based on cerebral cortex transcriptome data of neonates, we traced the initial nPM responses of HMGB1 pathway. In vitro, mixed glia responded to 24 h nPM with lower HMGB1 protein and increased proinflammatory cytokines. This response was ameliorated by TLR4 knockdown. In sum, we identified transcriptional changes that could be associated with air pollution-mediated behavioral and phenotypic changes. These identified genes merit further mechanistic studies for therapeutic intervention development.

Mouse brain transcriptome responses to inhaled nanoparticulate matter differed by sex and APOE in Nrf2-Nfkb interactions

The neurotoxicity of air pollution is undefined for sex and APOE alleles. These major risk factors of Alzheimer's disease (AD) were examined in mice given chronic exposure to nPM, a nano-sized subfraction of urban air pollution. In the cerebral cortex, female mice had two-fold more genes responding to nPM than males. Transcriptomic responses to nPM had sex-APOE interactions in AD-relevant pathways. Only APOE3 mice responded to nPM in genes related to Abeta deposition and clearance (Vav2, Vav3, S1009a). Other responding genes included axonal guidance, inflammation (AMPK, NFKB, APK/JNK signaling), and antioxidant signaling (NRF2, HIF1A). Genes downstream of NFKB and NRF2 responded in opposite directions to nPM. Nrf2 knockdown in microglia augmented NFKB responses to nPM, suggesting a critical role of NRF2 in air pollution neurotoxicity. These findings give a rationale for epidemiologic studies of air pollution to consider sex interactions with APOE alleles and other AD-risk genes.

Female vulnerability to the effects of smoking on health outcomes in older people

Cigarette smoking is among the leading risk factors for mortality and morbidity. While men have a higher smoking prevalence, mechanistic experiments suggest that women are at higher risk for health problems due to smoking. Moreover, the comparison of smoking effects on multiple conditions and mortality for men and women has not yet been done in a population-based group with race/ethnic diversity. We used proportional hazards models and restricted mean survival time to assess differences in smoking effects by sex for multiple health outcomes using data from the U.S. Health and Retirement Study (HRS), a population-representative cohort of individuals aged 50+ (n = 22,708, 1992-2014). Men had experienced more smoking pack-years than women (22.0 vs 15.6 average pack-years). Age of death, onset of lung disorders, heart disease, stroke, and cancer showed dose-dependent effects of smoking for both sexes. Among heavy smokers (>28 pack-years) women had higher risk of earlier age of death (HR = 1.3, 95%CI:1.03-1.65) and stroke (HR = 1.37, 95%CI:1.02-1.83). Risk of cancer and heart disease did not differ by sex for smokers. Women had earlier age of onset for lung disorders (HR = 2.83, 95%CI:1.74-4.6), but men risk due to smoking were higher (Smoking-Sex interaction P<0.02) than women. Passive smoke exposure increased risk of earlier heart disease (HR = 1.33, 95%CI:1.07-1.65) and stroke (HR:1.54, 95%CI:1.07-2.22) for non-smokers, mainly in men. Smoking cessation after 15 years partially attenuated the deleterious smoking effects for all health outcomes. In sum, our results suggest that women are more vulnerable to ever smoking for earlier death and risk of stroke, but less vulnerable for lung disorders. From an epidemiological perspective, sex differences in smoking effects are important considerations that could underlie sex differences in health outcomes. These findings also encourage future mechanistic experiments to resolve potential mechanisms of sex-specific cigarette smoke toxicity.

Acute versus Chronic Exposures to Inhaled Particulate Matter and Neurocognitive Dysfunction: Pathways to Alzheimer's Disease or a Related Dementia

An estimated 92% of the world's population live in regions where people are regularly exposed to high levels of anthropogenic air pollution. Historically, research on the effects of air pollution have focused extensively on cardiovascular and pulmonary health. However, emerging evidence from animal and human studies has suggested that chronic exposures to air pollution detrimentally change the functioning of the central nervous system with the result being proteinopathy, neurocognitive impairment, and neurodegenerative disease. Case analyses of aging World Trade Center responders suggests that a single severe exposure may also induce a neuropathologic response. The goal of this report was to explore the neuroscientific support for the hypothesis that inhaled particulate matter might cause an Alzheimer's-like neurodegenerative disease, in order to consider proposed mechanisms and latency periods linking inhaled particulate matter and neurodegeneration, and to propose new directions in this line of research.