Neurodevelopmental toxicity induced by maternal PM2.5 exposure and protective effects of quercetin and Vitamin C

Amelioration of metabolic disorders in H9C2 cardiomyocytes induced by PM2.5 treated with vitamin C

OBJECTIVE

Particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) is a public health risk. We investigate PM2.5 on metabolites in cardiomyocytes and the influence of vitamin C on PM2.5 toxicity.

MATERIALS AND METHODS

For 24 hours, H9C2 were exposed to various concentrations of PM2.5 (0, 100, 200, 400, 800 μg/ml), after which the levels of reactive oxygen species (ROS) and cell viability were measured using the cell counting kit-8 (CCK-8) and 2',7'-dichlorofluoresceindiacetate (DCFH2-DA), respectively. H9C2 were treated with PM2.5 (200 μg/ml) in the presence or absence of vitamin C (40 μmol/L). mRNA levels of interleukin 6(IL-6), caspase-3, fatty acid-binding protein 3 (FABP3), and hemeoxygenase-1 (HO-1) were investigated by quantitative reverse-transcription polymerase chain reaction. Non-targeted metabolomics by LC-MS/MS was applied to evaluate the metabolic profile in the cell.

RESULTS

Results revealed a concentration-dependent reduction in cell viability, death, ROS, and increased expression of caspase-3, FABP3, and IL-6. In total, 15 metabolites exhibited significant differential expression (FC > 2, p < 0.05) between the control and PM2.5 group. In the PM2.5 group, lysophosphatidylcholines (LysoPC,3/3) were upregulated, whereas amino acids (5/5), amino acid analogues (3/3), and other acids and derivatives (4/4) were downregulated. PM2.5 toxicity was lessened by vitamin C. It reduced PM2.5-induced elevation of LysoPC (16:0), LysoPC (16:1), and LysoPC (18:1).

DISCUSSION AND CONCLUSIONS

PM2.5 induces metabolic disorders in H9C2 cardiomyocytes that can be ameliorated by treatment with vitamin C.

Phosphocholine-induced energy source shift alleviates mitochondrial dysfunction in lung cells caused by geospecific PM2.5 components

Fine particulate matter (PM2.5) is globally recognized for its adverse implications on human health. Yet, remain limited the individual contribution of particular PM2.5 components to its toxicity, especially considering regional disparities. Moreover, prevention solutions for PM2.5-associated health effects are scarce. In the present study, we comprehensively characterized and compared the primary PM2.5 constituents and their altered metabolites from two locations: Taiyuan and Guangzhou. Analysis of year-long PM2.5 samples revealed 84 major components, encompassing organic carbon, elemental carbon, ions, metals, and organic chemicals. PM2.5 from Taiyuan exhibited higher contamination, associated health risks, dithiothreitol activity, and cytotoxicities than Guangzhou's counterpart. Applying metabolomics, BEAS-2B lung cells exposed to PM2.5 from both cities were screened for significant alterations. A correlation analysis revealed the metabolites altered by PM2.5 and the critical toxic PM2.5 components in both regions. Among the PM2.5-down-regulated metabolites, phosphocholine emerged as a promising intervention for PM2.5 cytotoxicities. Its supplementation effectively attenuated PM2.5-induced energy metabolism disorder and cell death via activating fatty acid oxidation and inhibiting Phospho1 expression. The highlighted toxic chemicals displayed combined toxicities, potentially counteracted by phosphocholine. Our study offered a promising functional metabolite to alleviate PM2.5-induced cellular disorder and provided insights into the geo-based variability in toxic PM2.5 components.

Neurotoxicity of the air-borne particles: From molecular events to human diseases

Exposure to PM_2.5 is associated with an increased incidence of CNS diseases in humans, as confirmed by numerous epidemiological studies. Animal models have demonstrated that PM_2.5 exposure can damage brain tissue, neurodevelopmental issues and neurodegenerative diseases. Both animal and human cell models have identified oxidative stress and inflammation as the primary toxic effects of PM_2.5 exposure. However, understanding how PM_2.5 modulates neurotoxicity has proven challenging due to its complex and variable composition. This review aims to summarize the detrimental effects of inhaled PM_2.5 on the CNS and the limited understanding of its underlying mechanism. It also highlights new frontiers in addressing these issues, such as modern laboratory and computational techniques and chemical reductionism tactics. By utilizing these approaches, we aim to fully elucidate the mechanism of PM_2.5-induced neurotoxicity, treat associated diseases, and ultimately eliminate pollution.

Salidroside pretreatment alleviates PM2.5 caused lung injury via inhibition of apoptosis and pyroptosis through regulating NLRP3 Inflammasome

Ambient fine particulate matter (PM_2.5) is considered a leading cause of pathogenic particulate matter induced lung injury. And Salidroside (Sal), the major bioactive constituent isolated from Rhodiola rosea L., has been shown to ameliorate lung injury in various conditions. To uncover the possible therapy for PM_2.5 related pulmonary disease, we evaluated the protective role of Sal pre-treatment on PM_2.5 induced lung injury in mice by utilizing the survival analysis, hematoxylin and eosin (H&E) staining, lung injury score, lung wet-to-dry weight ratio, enzyme-linked immunosorbent assay (ELISA) kits, immunoblot, immunofluorescence, and transmission electron microscopy (TEM). Impressively, our findings strongly indicated Sal as an effective precaution against PM_2.5 induced lung injury. Pre-administration of Sal before PM_2.5 treatment reduced the mortality within 120 h and alleviated inflammatory responses by reducing the release of proinflammatory cytokines, including TNF-α, IL-1β, and IL-18. Meanwhile, Sal pretreatment blocked apoptosis and pyroptosis that introduced the tissue damage under PM_2.5 treatment via regulating Bax/Bcl-2/caspase-3 and NF-κB/NLRP3/caspase-1 signal pathways. In summary, our research demonstrated that Sal could be a potential preventative therapy for PM_2.5 caused lung injury by inhibiting the initiation and development of apoptosis and pyroptosis through down-regulating NLRP3 inflammasome pathway.

Effects of maternal urban particulate matter SRM 1648a exposure on birth outcomes and offspring growth in mice

The association between exposure to particulate matter (PM) during pregnancy and abnormal birth outcomes is still inconclusive. This study aims to provide more evidence for this public health concern by investigating birth outcomes and the growth of offspring in mice exposed to PM during pregnancy. C57BL/6 J pregnant mice were exposed to PM via nasal drip at three doses or solvent control. The dam weight gain was recorded during pregnancy. The number of pups, pup weight, and placental weight were recorded at embryonic day 18.5 (E18.5) necropsy. For mice that gave birth naturally, we calculated the gestation length and measured the body weight of offspring once a week from the 1st to the 6th week after birth. The results showed that there were no significant differences in maternal body weight gain, conception rate, pregnancy duration, and litter size among different groups. There were no significant differences in fetal weight, placental weight, and fetal/placental weight ratio at E18.5. Weight gain in offspring was reduced after birth. The average body weight of offspring in the high-dose group was significantly lower than that in the control group at weeks 5 in female pups. There were no significant differences in the body weight of male offspring among groups from 1st to the 6th. Together, our study indicated that maternal exposure to PM did not significantly impact birth outcomes of C57BL/6 J mice but affected growth trajectories in offspring after birth in a dose- and fetal sex-dependent manner.

Prenatal PM2.5 exposure impairs spatial learning and memory in male mice offspring: from transcriptional regulation to neuronal morphogenesis

BACKGROUND

As one of the environmental risk factors for human health, atmospheric fine particulate matter (PM_2.5) contributes to cognitive deterioration in addition to respiratory and cardiovascular injuries. Recently, increasing evidence implicates that PM_2.5 inhalation can affect neurological functions in offspring, but the sex-specific outcomes and the underlying biological processes are largely unknown.

OBJECTIVES

To observe the influence of prenatal PM_2.5 exposure on cognitive performance in offspring, to elucidate the neuronal morphological alterations and possible transcriptional regulation based on mRNA-sequencing (mRNA-Seq) data after birth, and to determine the key components of PM_2.5 contributing to the adverse effects.

METHODS

Pregnant C57BL/6J mice were exposed to sterile saline or PM_2.5 suspension. Morris water maze test was used to assess the cognitive function in weanling offspring. Microscopic observation was applied to detect neuronal morphogenesis in vivo and in vitro. The cortex tissues from male offspring were collected on postnatal days (PNDs) 1, 7, and 21 for mRNA-Seq analysis. The organic and inorganic components of PM_2.5 were separated to assess their contributions using primary cultured neurons.

RESULTS

Prenatal PM_2.5 exposure impaired spatial learning and memory in weanling male mice, but not female mice. The sex-specific outcomes were associated with mRNA expression profiles of the cortex during postnatal critical windows, and the annotations in Gene Ontology (GO) of differentially expressed genes (DEGs) revealed that the exposure persistently disrupted the expression of genes involved in neuronal features in male offspring. Consistently, axonal growth impairment and dendritic complexity reduction were observed. Importantly, Homeobox A5 (Hoxa5), a critical transcription factor regulating all of the neuronal morphogenesis-associated hub genes on PNDs 1, 7, and 21, significantly decreased in the cortex of male offspring following PM_2.5 exposure. In addition, both inorganic and organic components were harmful to axonal and dendritic growth, with organic components exhibiting stronger inhibition than inorganic ones.

CONCLUSION

Prenatal PM_2.5 exposure affected spatial learning and memory in male mice by disrupting Hoxa5-mediated neuronal morphogenesis, and the organic components, including polycyclic aromatic hydrocarbons (PAHs), posed more adverse effects than the inorganic components.

Maternal exposure to fine particulate matter and brain-derived neurotrophic factor (BDNF) in the fetus: A prospective cohort study

Maternal exposure to ambient fine particulate matter (PM_2.5) during pregnancy has been associated with impaired neurobehavioral development in children. However, the specific mechanism remains unclear. Brain derived neurotrophic factor (BDNF) is an important growth factor in the nervous system. We evaluated the associations of maternal PM_2.5 exposures with fetal BDNF in the umbilical cord blood in a prospective cohort study. A total of 711 eligible mother-infant pairs from the Shanghai Birth Cohort were included in the current study. Daily maternal exposures to ambient PM_2.5 were assessed with a gap-filling approach at 1 * 1 km² resolution based on self-reported home addresses. The concentrations of BDNF in the cord blood were measured by ELISA. A linear regression model was applied to evaluate the association of maternal ambient PM_2.5 exposure with fetal BDNF level at birth. The median concentration of BDNF was 13,403 pg/ml. Vaginal deliveries and female infants had higher BDNF levels than cesarean deliveries and male infants. One natural log (ln) unit increase in maternal PM_2.5 exposure during the second trimester was significantly associated with - 0.20 (95% CI: -0.36, -0.05) ln-unit decrease in BDNF level in all births. These effects were stronger and more significant in vaginal deliveries and in male infants. Our study suggests that BDNF in the cord blood may serve as a potential biomarker in assessing the neurodevelopmental effects of maternal PM_2.5 exposure.

The Potential Benefits of Quercetin for Brain Health: A Review of Anti-Inflammatory and Neuroprotective Mechanisms

Neuroinflammation is a critical factor in developing and progressing numerous brain diseases, including neurodegenerative diseases. Chronic or excessive neuroinflammation can lead to neurotoxicity, causing brain damage and contributing to the onset and progression of various brain diseases. Therefore, understanding neuroinflammation mechanisms and developing strategies to control them is crucial for treating brain diseases. Studies have shown that neuroinflammation plays a vital role in the progression of neurodegenerative diseases, such as Alzheimer's (AD) and Parkinson's (PD), and stroke. Additionally, the effects of PM2.5 pollution on the brain, including neuroinflammation and neurotoxicity, are well-documented. Quercetin is a flavonoid, a plant pigment in many fruits, vegetables, and grains. Quercetin has been studied for its potential health benefits, including its anti-inflammatory, antioxidant, and anti-cancer properties. Quercetin may also have a positive impact on immune function and allergy symptoms. In addition, quercetin has been shown to have anti-inflammatory and neuroprotective properties and can activate AMP-activated protein kinase (AMPK), a cellular energy sensor that modulates inflammation and oxidative stress. By reducing inflammation and protecting against neuroinflammatory toxicity, quercetin holds promise as a safe and effective adjunctive therapy for treating neurodegenerative diseases and other brain disorders. Understanding and controlling the mechanisms of NF-κB and NLRP3 inflammasome pathways are crucial for preventing and treating conditions, and quercetin may be a promising tool in this effort. This review article aims to discuss the role of neuroinflammation in the development and progression of various brain disorders, including neurodegenerative diseases and stroke, and the impact of PM2.5 pollution on the brain. The paper also highlights quercetin's potential health benefits and anti-inflammatory and neuroprotective properties.

Effects of urban particulate matter on gut microbiome and partial schizophrenia-like symptoms in mice: Evidence from shotgun metagenomic and metabolomic profiling

BACKGROUND

Epidemiological evidence reported that particulate matter (PM) was associated with increased schizophrenia (SCZ) risk. Disturbance of gut microbiome was involved in SCZ. However, it remains unclear whether PM induces SCZ-like symptoms and how gut microbiome regulates them. Therefore, a multi-omics animal experiment was conducted to verify how urban PM induces SCZ-like behavior and altered gut microbiota and metabolic pathways.

METHODS

Using a completely random design, mice were divided into three groups: PM group, control group and MK801 group, which received daily tracheal instillation of PM solution, sterile PBS solution and intraperitoneal injection of MK801 (establish SCZ model), respectively. After a 14-day intervention, feces were collected for multi-omics testing (shotgun metagenomic sequencing and untargeted metabolomic profiling), followed by open field test, tail suspension test, and passive avoidance test. Besides, fecal microbiome of PM group and control group were transplanted into "pseudo-sterile" mice, then behavioral tests were conducted.

RESULTS

Similar to MK801 group, mice in PM group showed SCZ-like symptoms, including increased spontaneous activity, excitability, anxiety and decreased learning and spatial memory. PM exposure significantly increased the relative abundance of Verrucomicrobia and decreased that of Fibrobacteres et al. The metabolism pathways of estrogen signaling (estriol, 16-glucuronide-estriol and 21-desoxycortisol) and choline metabolism (phosphocholine) were significantly altered by PM exposure. Verrucomicrobia was negatively correlated with the level of estriol, which was correlated with decreased learning and spatial memory. Fibrobacteres and Deinococcus-Thermus were positively correlated with the level of phosphocholine, which was correlated with increased spontaneous activity, excitability and anxiety. Fecal microbiome transplantation from PM group mice reproduced excitability and anxiety symptoms.

CONCLUSIONS

Exposure to PM may affect composition of gut microbiome and alterations of estrogen signaling pathway and choline metabolism pathway, which were associated with partial SCZ-like behaviors. But whether gut microbiome regulates these metabolic pathways and behaviors remains to be determined.

Neurodevelopmental toxicity induced by PM2.5 Exposure and its possible role in Neurodegenerative and mental disorders

Recent extensive evidence suggests that ambient fine particulate matter (PM2.5, with an aerodynamic diameter ≤2.5 μm) may be neurotoxic to the brain and cause central nervous system damage, contributing to neurodevelopmental disorders, such as autism spectrum disorders, neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease, and mental disorders, such as schizophrenia, depression, and bipolar disorder. PM2.5 can enter the brain via various pathways, including the blood-brain barrier, olfactory system, and gut-brain axis, leading to adverse effects on the CNS. Studies in humans and animals have revealed that PM2.5-mediated mechanisms, including neuroinflammation, oxidative stress, systemic inflammation, and gut flora dysbiosis, play a crucial role in CNS damage. Additionally, PM2.5 exposure can induce epigenetic alterations, such as hypomethylation of DNA, which may contribute to the pathogenesis of some CNS damage. Through literature analysis, we suggest that promising therapeutic targets for alleviating PM2.5-induced neurological damage include inhibiting microglia overactivation, regulating gut microbiota with antibiotics, and targeting signaling pathways, such as PKA/CREB/BDNF and WNT/β-catenin. Additionally, several studies have observed an association between PM2.5 exposure and epigenetic changes in neuropsychiatric disorders. This review summarizes and discusses the association between PM2.5 exposure and CNS damage, including the possible mechanisms by which PM2.5 causes neurotoxicity.

Neurodevelopmental toxicity induced by airborne particulate matter

Airborne particulate matter (PM), the primary component associated with health risks in air pollution, can negatively impact human health. Studies have shown that PM can enter the brain by inhalation, but data on the exact quantity of particles that reach the brain are unknown. Particulate matter exposure can result in neurotoxicity. Exposure to PM poses a greater health risk to infants and children because their nervous systems are not fully developed. This review paper highlights the association between PM and neurodevelopmental toxicity (NDT). Exposure to PM can induce oxidative stress and inflammation, potentially resulting in blood-brain barrier damage and increased susceptibility to development of neurodevelopmental disorders (NDD), such as autism spectrum disorders and attention deficit disorders. In addition, human and animal exposure to PM can induce microglia activation and epigenetic alterations and alter the neurotransmitter levels, which may increase risks for development of NDD. However, the systematic comparisons of the effects of PM on NDD at different ages of exposure are deficient. The elucidation of PM exposure risks and NDT in children during the early developmental stages are of great importance. The synthesis of current research may help to identify markers and mechanisms of PM-induced neurodevelopmental toxicity, allowing for the development of strategies to prevent permanent damage of developing brain.

Vascular benefits of vitamin C supplementation against fine particulate air pollution in healthy adults: A double-blind randomised crossover trial

Evidence on the health benefits of vitamin C supplementation in highly polluted areas has not been evaluated. We aimed to evaluate whether dietary vitamin C supplementation can improve vascular health linked to particulate matter (PM) exposure. A randomised double-blind crossover trial involving 58 health young adults was performed in Shijiazhuang, China in 2018. All subjects were randomly assigned to the vitamin C supplementation group (2000 mg/d) or placebo group for a week alternating with a 2 week washout period. Fifteen circulating biomarkers were measured. Linear mixed-effect model was applied to evaluate the effect of vitamin C supplementation on health outcomes. The average concentrations of PM_2.5 and PM₁₀ were 164.91 and 327.05 μg/m³, respectively. Vitamin C supplementation was significantly associated with a 19.47% decrease in interleukin-6 (IL-6), 17.30% decrease in tumour necrosis factor-a (TNF-α), 34.01% decrease in C-reactive protein (CRP), 3.37% decrease in systolic blood pressure (SBP) and 6.03% decrease in pulse pressure (PP). Furthermore, glutathione peroxidase (GSH-Px) was significantly increased by 7.15%. Sex-subgroup analysis showed that vitamin C significantly reduced TNF-α by 27.85% in male participants and significantly increased APOB by 6.28% and GSH-Px by 14.47% only in female participants. This study indicated that vitamin C supplementation may protect vascular vessels against PM exposure among healthy young adults in China.

Maternal urban particulate matter exposure and signaling pathways in fetal brains and neurobehavioral development in offspring

It is well understood that exposure to particulate matter (PM) can have adverse effects on the nervous system. When pregnant women are exposed to PM, their fetuses are also affected through the placenta. However, the mechanisms by which fetal brain development is regulated between mother and fetus remain unclear. C57BL/6J pregnant mice were exposed to PM at embryonic day (E) 2.5, 5.5, 8.5, 11.5, 14.5, and 17.5 via nasal drip at three doses (3, 6, 12 mg/kg of body weight) or PBS control. Neurobehavioral changes in the offspring were examined at 5-6-week-old by open field test (OFT) and elevated plus maze (EPM). The maternal and fetal brain and placenta were collected at E18.5, and molecular signal changes were explored using transcriptome analysis. We found that both male and female low-dose pups and male middle-dose pups traveled a significantly longer distance than controls in EPM tests. Both male and female low-dose pups showed a higher frequency of entering the center area and female low-dose pups exhibited a higher percentage of distance moved in the center area than controls in OFT tests. Gene expression in the maternal brain, fetal brain, and placenta at E18.5 was altered. Differentially expressed genes were enriched in the neuroactive ligand-receptor interaction pathway in all three tissue types. Pathway analysis revealed that the PI3K-Akt and PKC signaling was dysregulated in the fetal brain in the high-dose group compared with the control group. The pathways play a role in neuronal survival and apoptosis. Furthermore, there is a dose-dependent increase in Caspase-6, neuronal apoptosis and neurodegeneration biomarker, levels in E18.5 fetal brain (P = 0.06). In conclusion, our study demonstrated that prenatal PM exposure enhanced exploration and locomotor activity in adolescent offspring and altered molecular events in maternal brain, fetal brain, and placenta. The connections of these changes warrant further investigations.

Role of Environmental Toxicants on Neurodegenerative Disorders

Neurodegeneration leads to the loss of structural and functioning components of neurons over time. Various studies have related neurodegeneration to a number of degenerative disorders. Neurological repercussions of neurodegeneration can have severe impacts on the physical and mental health of patients. In the recent past, various neurodegenerative ailments such as Alzheimer’s and Parkinson’s illnesses have received global consideration owing to their global occurrence. Environmental attributes have been regarded as the main contributors to neural dysfunction-related disorders. The majority of neurological diseases are mainly related to prenatal and postnatal exposure to industrially produced environmental toxins. Some neurotoxic metals, like lead (Pb), aluminium (Al), Mercury (Hg), manganese (Mn), cadmium (Cd), and arsenic (As), and also pesticides and metal-based nanoparticles, have been implicated in Parkinson’s and Alzheimer’s disease. The contaminants are known for their ability to produce senile or amyloid plaques and neurofibrillary tangles (NFTs), which are the key features of these neurological dysfunctions. Besides, solvent exposure is also a significant contributor to neurological diseases. This study recapitulates the role of environmental neurotoxins on neurodegeneration with special emphasis on major neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease.

Food bioactives lowering risks of chronic diseases induced by fine particulate air pollution: a comprehensive review

Airborne particulate matter (PM) exerts huge negative impacts on human health worldwide, not only targeting the respiratory system but more importantly inducing and aggravating associated chronic diseases like asthma, lung cancer, atherosclerosis, diabetes mellitus and Alzheimer diseases. Food-derived bioactive compounds like vitamins, dietary polyphenols, omega-3 polyunsaturated fatty acids and sulforaphane are feasible alternative therapeutic approaches against PM-mediated potential health damages, drawing great attention in recent years. In this review, the association between PM exposure and risks of developing chronic diseases, and the detailed mechanisms underlying the detrimental effects of PM will be discussed. Subsequently, principal food-derived bioactive compounds, with emphasize on the preventative or protective effects against PM, along with potential mechanisms will be elucidated. This comprehensive review will discuss and present current research findings to reveal the nutritional intervention as a preventative or therapeutic strategy against ambient air pollution, thereby lowering the risk of developing chronic diseases.

Ambient PM2.5-induced brain injury is associated with the activation of PI3K/AKT/FoxO1 pathway

PM_2.5-related neurological and mental diseases, such as cognitive impairment and stroke, tend to cause disability. Six-week-old male C57BL/6 mice were divided into 6 groups and exposed to concentrated PM_2.5 or filtered air for 2, 4, and 6 months, respectively. The neurobehavioral changes of mice were tested. The weight of the whole brain and olfactory bulbs were recorded at the end of exposure, and the brain structure was observed by hematoxylin and eosin (HE) staining. Serum indicators, mRNA, and protein expressions were detected. The spatial learning memory ability was impaired, and the mice were more anxious after PM_2.5 exposure. Relative brain weight decreased with age, and PM_2.5 exposure exceeded the decrease of relative brain weight. Interestingly, superoxide dismutase (SOD) and albumin decreased in the PM_2.5-exposed groups although neuronal morphology and other serum indicators did not show significant difference between PM and FA groups. Moreover, PM_2.5 induced the increase of plasminogen at 2 months but recovered at 4 months and then increased at 6 months again. The results from protein expression and transcriptomic test demonstrated that PI3K/AKT/FoxO1 pathway might be activated after 6-month PM_2.5 exposure in mice. Indicators albumin, the percentage of albumin over IgG (A/G value), and plasminogen were the main serous changes in mice after early-stage (2 months) and long-term (6 months) PM_2.5 exposure. In addition, early-stage injury induced by PM_2.5 might recover at later time point and display significant injury again with the exposure time. PM_2.5 exposure-induced brain injury might be associated with the activation of PI3K/AKT/FoxO1 pathway.

Exposure to PM2.5 during pregnancy causes lung inflammation in the offspring: Mechanism of action of mogrosides

Epidemiological and toxicological studies have demonstrated that exposure to fine particulate matter (PM2.5) during pregnancy is harmful to the tissues of the offspring. However, the mechanism by which PM2.5 exposure causes lung damage in the offspring or potential dietary therapy for this condition remains unclear. Mogrosides (MGs) are derived from the traditional plant Siraitia grosvenorii and are used medicinally, where they can moisten the lungs and relieve coughing. In this study, pregnant rats were exposed to PM2.5 by intratracheal instillation and treated with MGs by gavage to model the effect of PM2.5 in the offspring and the interventional effect of MGs on lung tissue. We then used transcriptomics, metabolomics, and RT-qPCR as tools to look for metabolite and genetic changes in the offspring. We found that when compared to the control group, the mRNA levels of the inflammatory mediator Pla2g2d and the metabolites lysophosphatidylcholines (LysoPCs) and arachidonic acid (AA) were up-regulated in the lung tissues of PM2.5 group. In contrast, these inflammatory changes were restored after treatment with MGs during pregnancy. In addition, the levels of AA, LPC 15:0 and LPC 18:0 were elevated in the PM2.5 group compared with control group. This increase was inhibited by co-administration of MGs. The change of PGA1 was adverse. In conclusion, even a relatively low exposure to PM2.5 in rats during pregnancy produces inflammation in the lungs of the male offspring, and an intervention with MGs could significantly alleviate this effect. Furthermore, Pla2g2d may represent a potential target for MGs resulting in the improvement of PM2.5-induced lung injury.

Gestational exposure to PM2.5 leads to cognitive dysfunction in mice offspring via promoting HMGB1-NLRP3 axis mediated hippocampal inflammation

PM_2.5 is recently identified as a kind of material possessing severe biohazard. It can enter human body and exerts pathological effects on lung, eyes, and the central nervous system (CNS). Maternal exposure to PM_2.5 can affect neural development and cause cognitive decline in offspring, with the underlying mechanisms unclear, however. The inflammasome monitors and responds to biological stressors, with HMGB1-NLRP3 inflammatory axis as an essential pathophysiological player outside the brain. The present work is to investigate its role in cognitive impairment induced by gestational exposure to PM_2.5 in mice offspring. We found that HMGB1-NLRP3 pathway was activated in the hippocampus of mice offspring by gestational exposure to PM_2.5 in a dose-dependent manner, with protein levels of HMGB1, NLRP3, and cleaved caspase-1 as approximately three times as high as those of control. And down-regulating HMGB1 during pregnancy could alleviate the resultant impairment on learning and working memory as well as hippocampal neurons, up-regulate the synapse related proteins of SYP and PSD-95 and correct the increased expression of 5-HT2A to comparable levels to control, as well as inhibiting the activation of microglia and decreasing the expression of HMGB1 and Iba1/HMGB1 double positive cells in the hippocampus of mice offspring. Meanwhile, protein levels of NLRP3, cleaved caspase-1, IL-1β and IL-18, as well as TLR4, phosphorylated NF_-κB, and MAPKs, were almost down-regulated to those of control. Therefore, HMGB1 intervention inhibits the NLRP3 inflammasome mediated hippocampal inflammatory response through TLR4/MAPKs/NF-κB signaling pathway, alleviating PM_2.5-induced cognitive dysfunction. Further in vitro results suggest that PM_2.5 can activate microglia and HMGB1-NLRP3 inflammatory axis. Pretreatment with HMGB1 inhibitor significantly reduced the phosphorylation of MAPKs and NF-κB, and inhibited the inflammatory response mediated by NLRP3 inflammasome similarly to those in vivo. These results suggest that PM_2.5 exposure promotes the inflammatory response in hippocampus mediated by HMGB1-NLRP3 inflammatory axis in microglia, resulting in cognitive dysfunction in offspring, which could be alleviated by simultaneous HMGB1 suppression. These findings provide a theoretical basis for preventing cognitive impairment in offspring caused by environmental pollution during pregnancy.

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.

Role of PKA/CREB/BDNF signaling in PM2.5-induced neurodevelopmental damage to the hippocampal neurons of rats

Exposure to fine particulate matter (PM2.5) is implicated in neurodevelopmental disorders including cognitive decline, attention-deficit/hyperactivity disorder, and autism spectrum disorder. However, the specific molecular mechanisms by which PM2.5 impacts neurodevelopment are poorly understood. Accordingly, in the present study, the role of protein kinase A (PKA)/cAMP response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling in PM2.5-induced neurodevelopmental damage was investigated using primary cultured hippocampal neurons. When hippocampal neurons cultured for 3 days in vitro (DIV3) were exposed to PM2.5 for 24 h and 96 h, neuronal viability decreased by 18.8% and 32.7% respectively, percentage of TUNEL-positive neurons increased by 78.5% and 64.0% separately, caspase-9 expression increased, lower postsynaptic density and shorter active zones were observed by transmission electron microscopy, expression of synapse-related proteins including postsynaptic density-95 (PSD95), growth associated protein-43 (GAP43), and synaptophysin (SYP) were decreased, and the phosphorylation levels of PKA, CREB, and BDNF expression also decreased. However, the PM2.5-induced neuronal damage could be ameliorated or aggravated to varying degrees by up- or down-regulation of the PKA/CREB/BDNF signaling pathway, respectively. Our results indicate that PM2.5 exposure exerts neurodevelopmental toxicity as indicated by lower viability, apoptosis, and synaptic damage in primary cultured hippocampal neurons, and that the PKA/CREB/BDNF pathways could play a vital role in PM2.5-mediated neurodevelopmental toxicity.

Nutraceuticals with anti-inflammatory and anti-oxidant properties as intervention for reducing the health effects of fine particulate matter: Potential and Prospects

Air pollution, especially particulate matter pollution adversely affects human health. A growing pool of evidence has emerged which underscores the potential of individual-level nutritional interventions in attenuating the adverse health impact of exposure to PM2.5. Although controlling emission and reducing the overall levels of air pollution remains the ultimate objective globally, the sustainable achievement of such a target and thus consequent protection of human health will require a substantial amount of time and concerted efforts worldwide. In the meantime, smaller-scale individual-level interventions that can counter the inflammatory or oxidative stress effects triggered by exposure to particulate matter may be utilized to ameliorate the health effects of PM2.5 pollution. One such intervention is incorporation of nutraceuticals in the diet. Here, we present a review of the evidence generated from various in vitro, in vivo and human studies regarding the effects of different anti-inflammatory and antioxidant nutraceuticals in ameliorating the health effects of particulate matter air pollution. The studies discussed in this review suggest that these nutraceuticals when consumed as a part of the diet, or as additional supplementation, can potentially negate the cellular level adverse effects of exposure to particulate pollution. The potential benefits of adopting a non-pharmacological diet-based approach to air pollution-induced disease management have also been discussed. We argue that before a nutraceuticals-based approach can be used for widespread public adoption, further research, especially human clinical trials, is essential to confirm the beneficial action of relevant nutraceuticals and to explore the safe limits of human supplementation and the risk of side effects. Future research should focus on systematically translating bench-based knowledge regarding nutraceuticals gained from in-vitro and in-vivo studies into clinically usable nutritional guidelines.

Maternal Quercetin Consumption during Pregnancy May Help Regulate Total Cholesterol/HDL-Cholesterol Ratio without Effect on Cholesterol Levels in Male Progeny Consuming High-Fat Diet

Quercetin has been shown to have anti-obesity effects, but it is unknown whether these effects can be transmitted from mothers to their progeny. In this study, we investigated whether maternal quercetin consumption during pregnancy has a protective effect on high-fat diet-induced hyper lipid levels and overweight in progeny. Female mice consumed a control diet or a diet containing 1.0% quercetin during breeding. The male progeny were then divided into four groups that were (1) sacrificed at postnatal day 3; (2) born to dams fed the control diet and also fed the control diet (C-C), (3) born to dams fed the control diet and then fed a 30% high-fat diet (C-HF), or (4) born to dams fed the Q-diet and then fed the HF diet (Q-HF). Maternal consumption of quercetin did not affect body weight or blood lipid parameters in either dams or neonates at postnatal day 3. After 13 weeks, the Q-HF group exhibited greater body and liver weights, and higher blood cholesterol levels than the C-HF group. However, the total cholesterol/ high density lipoprotein (HDL)-cholesterol ratios in the Q-HF and C-C groups remained similar. In conclusion, maternal quercetin consumption does not appear to protect the next generation from high-fat diet-induced hyper cholesterol level in the blood and liver, and consequently overweight, but may help regulate the total cholesterol/HDL-cholesterol ratio.

An Integrative Pharmacology-Based Strategy to Uncover the Mechanism of Xiong-Pi-Fang in Treating Coronary Heart Disease with Depression

Objectives: This study aimed to explore the mechanism of Xiong-Pi-Fang (XPF) in the treatment of coronary heart disease (CHD) with depression by an integrative strategy combining serum pharmacochemistry, network pharmacology analysis, and experimental validation. Methods: An ultrahigh performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS) method was constructed to identify compounds in rat serum after oral administration of XPF, and a component-target network was established using Cytoscape, between the targets of XPF ingredients and CHD with depression. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed to deduce the mechanism of XPF in treating CHD with depression. Finally, in a chronic unpredictable mild stress (CUMS)-and isoproterenol (ISO)-induced rat model, TUNEL was used to detect the apoptosis index of the myocardium and hippocampus, ELISA and western blot were used to detect the predicted hub targets, namely AngII, 5-HT, cAMP, PKA, CREB, BDNF, Bcl-2, Bax, Cyt-c, and caspase-3. Results: We identified 51 compounds in rat serum after oral administration of XPF, which mainly included phenolic acids, saponins, and flavonoids. Network pharmacology analysis revealed that XPF may regulate targets, such as ACE2, HTR1A, HTR2A, AKT1, PKIA, CREB1, BDNF, BCL2, BAX, CASP3, cAMP signaling pathway, and cell apoptosis process in the treatment of CHD with depression. ELISA analysis showed that XPF decreased Ang-II content in the circulation and central nervous system, inhibited 5-HT levels in peripheral circulation, and increased 5-HT content in the central nervous system and cAMP content in the myocardia and hippocampus. Meanwhile, western blot analysis indicated that XPF could upregulate the expression levels of PKA, CREB, and BDNF both in the myocardia and hippocampus. TUNEL staining indicated that the apoptosis index of myocardial and hippocampal cells increased in CUMS-and ISO-induced CHD in rats under depression, and XPF could increase the expression of Bcl-2, inhibit the expression of Bax, Cyt-c, and caspase-3, and rectify the injury of the hippocampus and myocardium, which exerted antidepressant and antimyocardial ischemia effects. Conclusion: Our study proposed an integrated strategy, combining serum pharmacochemistry and network pharmacology to investigate the mechanisms of XPF in treating CHD with depression. The mechanism of XPF in treating CHD with depression may be related to the activation of the cAMP signaling pathway and the inhibition of the apoptosis.

Natural compounds protect the skin from airborne particulate matter by attenuating oxidative stress

Particulate matter (PM) is a common indirect indicator of air pollution and threatens public health upon prolonged exposure, leading to oxidative stress, increasing the risk of develop respiratory and cardiovascular, as well as several autoimmune diseases and cancer. Nowadays, as a first line defense against PM, skin health attracted much attention. Our review summarized the skin damage mechanism induced by PM, including damage skin barrier directly, reactive oxygen species (ROS) accumulation, autophagy, and two canonical signaling pathways. Furthermore, ROS and oxidative stress have been considered pathogenesis centers, with essential skin damage roles. Extracts from plants and natural compounds which present high antioxidant capacity could be used to treat or protect against air pollution-related skin damage. We conclude the extracts reported in recent studies with protective effects on PM-mediated skin damage. Besides, the mechanism of extracts' positive effects has been revealed partially.

Ecklonia cava Attenuates PM2.5-Induced Cognitive Decline through Mitochondrial Activation and Anti-Inflammatory Effect

To evaluate the effects of Ecklonia cava (E. cava) on ambient-pollution-induced neurotoxicity, we used a mouse model exposed to particulate matter smaller than 2.5 µm in aerodynamic diameter (PM2.5). The intake of water extract from E. cava (WEE) effectively prevented the learning and memory decline. After a behavioral test, the toll-like receptor (TLR)-4-initiated inflammatory response was confirmed by PM2.5 exposure in the lung and brain tissues, and the WEE was regulated through the inhibition of nuclear factor-kappa B (NF-κB)/inflammasome formation signaling pathway and pro-inflammatory cytokines (IL-6 and IFN-γ). The WEE also effectively improved the PM2.5-induced oxidative damage of the lungs and brain through the inhibition of malondialdehyde (MDA) production and the activation of mitochondrial activity (mitochondrial ROS content, mitochondria membrane potential (MMP), adenosine triphosphate (ATP) content, and mitochondria-mediated apoptotic molecules). In particular, the WEE regulated the cognition-related proteins (a decreased amyloid precursor protein (APP) and p-Tau, and an increased brain-derived neurotrophic factor (BDNF)) associated with PM2.5-induced cognitive dysfunction. Additionally, the WEE prevented the inactivation of acetylcholine (ACh) synthesis and release as a neurotransmitter by regulating the acetylcholinesterase (AChE) activity, choline acetyltransferase (ChAT), and ACh receptor (AChR)-α3 in the brain tissue. The bioactive compounds of the WEE were detected as the polysaccharide (average Mw; 160.13 kDa) and phenolic compounds including 2'-phloroeckol.

Pre-pregnancy exposure to fine particulate matter (PM2.5) increases reactive oxygen species production in oocytes and decrease litter size and weight in mice

Exposure of females to fine particulate matter ≤2.5 μm in diameter (PM2.5) prior to pregnancy could produce adverse impact on fertility and enhances susceptibility of the offspring to a variety of diseases. In the current study, female C57BL/6 mice (6 weeks of age) were exposed to either concentrated PM2.5 or filtered air (average PM2.5 concentration: 115.60 ± 7.77 vs. 14.07 ± 0.38 μg/m^-3) using a whole-body exposure device for 12 weeks. Briefly, PM2.5 exposure decreased anti-Müllerian hormone level (613.40 ± 17.36 vs 759.30 ± 21.90 pg mL^-1, P＜0.01) and increased reactive oxygen species (ROS) level (45.39 ± 0.82 vs 24.20 ± 0.85 arbitrary unit in fluorescence assay, P＜0.01) in oocytes. The exposure increased oocyte degeneration rate (21.5% vs 5.1%, respectively (P＜0.01) and decreased the 2-cell formation rate (71.9% vs 86.0%, P < 0.01). Transcriptome profiling using RNA sequencing showed wide spectrum of abnormal expression of genes, particularly those involved in regulating the mitochondrial respiratory complex in oocytes and metabolic processes in blastocysts. The exposure decreased litter size (6 ± 0.37 vs 7 ± 0.26, P＜0.05) and weight (1.18 ± 0.02 vs 1.27 ± 0.02 g, P＜0.01). In summary, PM2.5 exposure decreased female fertility, possibly through increased ROS production in oocytes and metabolic disturbances in developing embryos. The cause-effect relationship, however, requires further investigation.

Sex-specific effects of PM2.5 maternal exposure on offspring's serum lipoproteins and gut microbiota

Fine particulate matter (PM_2.5), which is known to impact public health, has received widespread attention recently. However, the long-term impact of maternal PM_2.5 exposure remains unclear. To illuminate whether maternal PM_2.5 exposure can affect serum lipoproteins and intestinal flora of offspring, mice received PM_2.5 by intratracheal instillation during gestation and lactation. On postnatal day (PND) 35, serum lipoproteins of male and female pups were measured. Additionally, gut microbiota of offspring on PND 3, 10, 21 and 35 were measured by 16S rDNA sequencing of the colon contents. A higher serum triglyceride (TG) concentration in male offspring was observed in the exposed PM_2.5 group (p < 0.05) compared with the control group, while there was no significant difference in lipoproteins for female offspring. On PND 35, Bacteroides, Desulfovibrio, and Anaerotruncus were enriched in the male offspring of the PM_2.5-exposed group, and the control group had an increased abundance of Streptococcus. However, for female offspring on PND35, Clostridium XI was found to be enriched in the control group. A positive correlation between Bacteroides and serum TG concentration (r = 0.47, p = 0.02) was determined by Spearman's correlation analysis. These results suggest that serum TG and gut microbiota of offspring could be influenced by maternal PM_2.5 exposure in a sex-specific manner. Abnormal lipid metabolism might be relevant to the changes of gut microbiota.

Transgenerational transmission of neurodevelopmental disorders induced by maternal exposure to PM2.5

The pathological traits or diseases susceptibility caused by maternal exposure to environmental adverse insults (infection, malnutrition, environmental toxicants) could be transmitted across generations. It remains uncertain, however, whether the neurodevelopmental disturbances of offspring induced by maternal exposure to PM2.5 during early life can be inherited by subsequent generations without further exposure. In the current study, using transgenerational animal models, we found that F1 female showed poorer performance in Morris Water Maze (MWM), and the deficits in spatial learning and memory similarly presented in F2-F3 female. The transgenerationally-transmitted neurobehavioral disorders were mediated both via maternal and paternal lineage. Since the epigenetic modifications have been reported to be involved in the disturbed neurodevelopment induced by maternal exposure to detrimental environmental factors during early life, we further explored the possible epigenetic mechanism of the transgenerational effects. Intriguingly, the results displayed the significant increase in expression of Dnmt3a in F1 female offspring. And the hypermethylation of Bdnf promoter Ⅳ and downregulated expression of Bdnf in hippocampus were stably transmitted across the generations until the third generation. There was another interesting finding that the transgenerational effects were sex-specific and only emerged in female offspring. Together, our study indicated for the first time that maternal exposure to PM2.5 during early life could detrimentally affect neurobehaviors in multiple generations, and the declined expression of Bdnf induced by hypermethylation of Bdnf promoter Ⅳ mediated by Dnmts might be the potential molecular mechanism.

Parental PM2.5 Exposure-Promoted Development of Metabolic Syndrome in Offspring Is Associated With the Changes of Immune Microenvironment

Parental exposure to ambient fine particulate matter (PM2.5) has been associated with some of adverse health outcomes in offspring. The association between parental PM2.5 exposure and the development of metabolic syndrome (MetS) in offspring, and the effects of parental PM2.5 exposure on the susceptibility of offspring mice to PM2.5, has not been evaluated. The C57BL/6 parental mice (male and female mice) were exposed to filtered air (FA) or concentrated PM2.5 (PM) using Shanghai-METAS for a total of 16 weeks. At week 12 during the exposure, we allowed the parental male and female mice to breed offspring mice. The male offspring mice were divided into 4 groups and exposed to PM and FA again. The results showed that whether the parental mice were exposed to PM2.5 or not, the offspring mice exposure to PM2.5 appeared the elevation of blood pressure, insulin resistance, impairment of glucose tolerance, and dyslipidemia when compared to the offspring mice exposure to FA. More importantly, no matter what the offspring mice were exposed to, parental PM exposure overwhelmingly impacted the fasting blood insulin, homeostasis model assessment-insulin resistance, serous low-density lipoprotein cholesterol, and total cholesterol, splenic T helper cell 17 (Th17) and Treg cells, serous interleukin (IL)-17A, IL-6, and IL-10 in offspring mice. The results suggested that the parental exposure to air pollution might induce the development of MetS in offspring and might enhance the susceptibility of offspring to environmental hazards. The effects of parental PM exposure on offspring might be related to the changes of immune microenvironment.

Interaction between aspirin and vitamin C with human serum albumin as binary and ternary systems

Foods generally contain special ingredients which easily to interact with drugs human intaking, thus affecting drug efficacy and excretion, and even cause adverse reactions. Vitamin C (Vit. C) is abundant in fresh fruits and vegetables. It plays a regulatory role in redox metabolism, and its absence can cause scurvy. Aspirin (ASP) can be used to treat many diseases, is the earliest, common and widely used as antipyretic, analgesic and antirheumatic medicine. Human serum albumin (HSA) is the most abundant protein in vertebrate plasma and has the property of combining and transporting endogenous and exogenous substances. In this paper, the effects of Vit. C on the combination of ASP and HSA were studied by multi-spectra and voltammetric approaches. Fluorescence spectra showed that the quenching mode between Vit. C and HSA is dynamic, and the main binding force is hydrophobic force. The quenching mode between ASP and HSA is static one, and the main binding force is hydrogen bond and van der Waals force. For ternary biological system of (HSA-ASP)-Vit. C, the binding constant decreases compared with HSA-Vit. C system. However, for (HSA-Vit. C)-ASP system, the binding constant does not change when compared with binary system of HSA-ASP. Based on the technology combination of voltammetry, infrared, three-dimensional fluorescence and circular dichroism (CD), it is proved that the existence of ASP will influence the binding process of Vit. C to HSA. It could be concluded that taking Vit. C first doesn't affect the absorption of ASP and may be good for health; in contrast, it is not good to take Vit. C immediately as one have just taken ASP, because the existence of ASP reduce the absorption of Vit. C for human body.

Combined exposure of fine particulate matter and high-fat diet aggravate the cardiac fibrosis in C57BL/6J mice

Cardiac fibrosis is associated with fine particulate matter (PM_2.5) exposure. In addition, whether high-fat diet (HFD) could exacerbate the PM_2.5-induced cardiac injury was unevaluated. Thus, this study was aimed to investigate the combined effects of PM_2.5 and HFD on cardiac fibrosis. The echocardiography and histopathological analysis showed that co-exposure of PM_2.5 and HFD had a significant deleterious effect on both cardiac systolic and diastolic function accompanied the myofibril disorder and myocardial fibrosis in C57BL/6 J mice than exposed to PM_2.5 or HFD alone. The augmented oxidative damage and increased α-SMA area percentage were detected in heart tissue of mice exposed to PM_2.5 and HFD together. PM_2.5 upregulated the expressions of cardiac fibrosis-related special markers, including collagen-I, collagen-III, TGF-β1, p-Smad3 and total Smad3, which had more pronounced activations in co-exposure group. Meanwhile, the factorial analysis exhibited the synergistic interaction regarded to the combined exposure of PM_2.5 and HFD. Simultaneously, PM_2.5 and palmitic acid increased intracellular ROS generation and activated the TGF-β1/Smad3 signaling pathway in cardiomyocytes. While the ROS scavenger NAC had effectively attenuated the ROS level and suppressed the TGF-β1/Smad3 signaling pathway. Taken together, our results demonstrated combined exposure to PM_2.5 and HFD could aggravate cardiac fibrosis via activating the ROS/TGF-β1/Smad3 signaling pathway.

Effects of PM2.5 exposure during gestation on maternal gut microbiota and pregnancy outcomes

A number of studies have reported that fine particulate matter (PM_2.5) exposure is associated with adverse pregnancy outcomes. Moreover, PM_2.5 exposure contributes to changes of gut microbiota. However, influences of PM_2.5 exposure during gestation on maternal gut microbiota and pregnancy outcomes were not well understood. Here we performed a study using mice models. Dams were exposed to PM_2.5 suspension by intratracheal instillation on gestational day (GD) 3, 6, 9, 12 and 15. Pregnancy outcomes, maternal gut microbiota and short chain fatty acids on GD 18 were all measured. The fetal body weight of PM_2.5 group was significantly lower than that of control group (p < 0.05). Meanwhile, the fetal body length of PM_2.5 group was significantly shorter than that of control group (p < 0.05). The Shannon or Simpson index of PM_2.5 group were higher than that of control group (p < 0.05). At the phyla level, compared to dams in control group, mice in the PM_2.5 group had higher ratio of phyla Proteobacteria, Candidatus Saccharibacteria and Fusobacteria and lower ratio of phyla Acidobacteria, Gemmatimonadetes and Deferribacteres in the gut. Compared with control group, the concentration of isobutyric acid was higher in PM_2.5 group, but butyric acid concentration was lower in PM_2.5 group (p < 0.05). These findings suggested that prenatal exposure to PM_2.5 had an effect on birth weight of fetus. Meanwhile, PM_2.5 tracheal exposure during gestation caused changes in the distribution and structure of gut microbiota of dams.

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

Air pollution (AirP) is associated with many neurodevelopmental and neurological disorders in human populations. Rodent models show similar neurotoxic effects of AirP particulate matter (PM) collected by different methods or from various sources. However, controversies continue on the identity of the specific neurotoxic components and mechanisms of neurotoxicity. We collected urban PM by two modes at the same site and time: direct collection as an aqueous slurry (sPM) versus a nano-sized sub-fraction of PM0.2 that was eluted from filters (nPM). The nPM lacks water-insoluble PAHs (polycyclic aromatic hydrocarbons) and is depleted by >50% in bioactive metals (e.g., copper, iron, nickel), inorganic ions, black carbon, and other organic compounds. Three biological models were used: in vivo exposure of adult male mice to re-aerosolized nPM and sPM for 3 weeks, gestational exposure, and glial cell cultures. In contrast to larger inflammatory responses of sPM in vitro, cerebral cortex responses of mice to sPM and nPM largely overlapped for adult and gestational exposures. Adult brain responses included induction of IFNγ and NF-κB. Gestational exposure to nPM and sPM caused equivalent depressive behaviors. Responses to nPM and sPM diverged for cerebral cortex glutamate receptor mRNA, systemic fat gain and insulin resistance. The shared toxic responses of sPM with nPM may arise from shared transition metals and organics. In contrast, gestational exposure to sPM but not nPM, decreased glutamatergic mRNAs, which may be attributed to PAHs. We discuss potential mechanisms in the overlap between nPM and sPM despite major differences in bulk chemical composition.

Assessment of Interactions between Transition Metals and Atmospheric Organics: Ascorbic Acid Depletion and Hydroxyl Radical Formation in Organic-Metal Mixtures

Excessive oxidative stress has been recognized as an important cause of the adverse health effects associated with exposure to ambient particulate matter (PM). Transition metals (TMs) (e.g., iron (Fe) and copper (Cu)) are known catalysts in the formation of reactive oxygen species (ROS) in surrogate lung fluid containing antioxidants. Humic-like substances (HULIS), extracted from atmospheric aerosols, retain the compositional complexity of real-world samples. It contains mixtures of organics that chelate TMs and was used in this work to examine the roles of atmospheric organics in affecting ROS formation and antioxidant depletion by TMs. Two types of metal-binding organics known to be present in HULIS, oxygen-containing (i.e., carboxylic acids) and reduced-nitrogen-containing organics (i.e., imidazoles), were first investigated for their effects on the ascorbic acid depletion (denoted as OP_AA) and hydroxyl radical formation (denoted as OP_•OH) from both Fe(II) and Cu(II) in phosphate buffered saline (pH 7.40) containing ascorbic acid. Our results show that carboxylic acids enhance the OP_AA and OP_•OH by TMs while imidazoles suppress them. Similar experiments using three HULIS samples with distinctly different chemical compositions revealed complexity in metal-organics interactions. While ambient HULIS showed negligible impacts, two biomass burning source HULIS samples from rice straw and sugar cane leaf burning displayed unambiguous suppression or enhancement effects on OP_AA and OP_•OH by TMs. The effect was metal-specific and source HULIS-specific. The distinct behaviors of the three HULIS types can be explained by their different chemical compositions, for example, outstanding higher level of alkaloid compounds (e.g., imidazoles) in rice straw burning HULIS was consistent with the suppression effect exerted by this source of HULIS. In addition, we found OP_AA and OP_•OH are well-correlated while the proportion of OP_•OH/OP_AA by Cu is noticeably lower than that by Fe, indicating varying sensitivity of the metals to different OP end points. Our work highlights the importance and complexity of metal-organics interactions and the advantages of comeasurements of ROS generation and antioxidant depletion when assessing oxidative stress elicited by atmospheric PM.

Sex-Dependent Effects of PM2.5 Maternal Exposure and Quercetin Intervention on Offspring's Short Chain Fatty Acids

Short chain fatty acids (SCFAs) are produced by the colonic microbiota through fermentation. Influences of maternal PM_2.5 exposure on SCFAs of the offspring have not been well understood. Additionally, studies of dietary intervention have not been carried out yet. Here we performed a study that dams were received PM_2.5 and quercetin intervention during gestation and lactation. SCFAs in colon of dams and their offspring (on postnatal day 21 and 35) were analyzed using gas chromatography. For male offspring, when compared with the control group levels of acetic acid, butyric acid, and valeric acid were lower in the PM_2.5 group (p < 0.05), however, levels of isobutyric acid and isovaleric acid were higher in the PM_2.5 group (p < 0.05). For female offspring, as compared with the control group, propanoic acid was lower in the PM_2.5 group, however isovaleric acid was higher in the PM_2.5 group (p < 0.05). 100 mg/kg and 200 mg/kg quercetin intervention could inhibit SCFAs production of male offspring, especially in isobutyric acid and isovaleric acid (p < 0.05). 100 mg/kg quercetin intervention could upgrade the level of propanoic acid of female offspring (p < 0.05). Taken together, these results suggest that PM_2.5 tracheal exposure during gestation and lactation could influence SCFAs of offspring. Quercetin administration might have the potential to offset the effects of mater PM_2.5 exposure on SCFAs in the offspring to some extent. The above effects were showed in a sex-dependent manner.

Quercetin conjugated with superparamagnetic iron oxide nanoparticles improves learning and memory better than free quercetin via interacting with proteins involved in LTP

Biomedical application of quercetin (QT) as an effective flavonoid has limitations due to its low bioavailability. Superparamagnetic iron oxide nanoparticle (SPION) is a novel drug delivery system that enhances the bioavailability of quercetin. The effect of short time usage of quercetin on learning and memory function and its signaling pathways in the healthy rat is not well understood. The aim of this study was to investigate the effect of free quercetin and in conjugation with SPION on learning and memory in healthy rats and to find quercetin target proteins involved in learning and memory using Morris water maze (MWM) and computational methods respectively. Results of MWM show an improvement in learning and memory of rats treated with either quercetin or QT-SPION. Better learning and memory functions using QT-SPION reveal increased bioavailability of quercetin. Comparative molecular docking studies show the better binding affinity of quercetin to RSK2, MSK1, CytC, Cdc42, Apaf1, FADD, CRK proteins. Quercetin in comparison to specific inhibitors of each protein also demonstrates a better QT binding affinity. This suggests that quercetin binds to proteins leading to prevent neural cell apoptosis and improves learning and memory. Therefore, SPIONs could increase the bioavailability of quercetin and by this way improve learning and memory.