Effects of exposure to ambient fine particulate matter on the heart of diet-induced obesity mouse model

CKD patients comorbid with hypertension are associated with imbalanced gut microbiome

Intestinal flora has been linked to chronic kidney disease (CKD) and hypertension, respectively. This study aimed to investigate the microbial community among 54 individuals without CKD, 46 hypertensive CKD patients (CKD_HTN), and 48 non-hypertensive CKD patients. Variations in microbial diversity were detected in CKD. The Prevotella-dominated type progressively increased from CKD to CKD_HTN. Based on the variation patterns, we identified six distinct clusters. Klebsiella, Turicibacter, and Enterobacter were enriched in CKD, whereas Escherichia and Mogibacterium were elevated, and Blautia and Clostridium were reduced in CKD_HTN. Enhanced phenylalanine metabolism and siderophore group nonribosomal peptides biosynthesis from non-CKD to CKD were observed, particularly in CKD with hypertension. The connections between genera and KEGG pathways suggest an impact of microbial dysbiosis on metabolism. Our findings demonstrate that imbalances in gut microorganisms and functions are associated with increased susceptibility to hypertension in CKD patients and could be targeted for improving kidney function in CKD.

Molecular Pathways Linking High-Fat Diet and PM2.5 Exposure to Metabolically Abnormal Obesity: A Systematic Review and Meta-Analysis

Obesity, influenced by environmental pollutants, can lead to complex metabolic disruptions. This systematic review and meta-analysis examined the molecular mechanisms underlying metabolically abnormal obesity caused by exposure to a high-fat diet (HFD) and fine particulate matter (PM2.5). Following the PRISMA guidelines, articles from 2019 to 2024 were gathered from Scopus, Web of Science, and PubMed, and a random-effects meta-analysis was performed, along with subgroup analyses and pathway enrichment analyses. This study was registered in the Open Science Framework. Thirty-three articles, mainly case-control studies and murine models, were reviewed, and they revealed that combined exposure to HFD and PM2.5 resulted in the greatest weight gain (82.835 g, p = 0.048), alongside increases in high-density lipoproteins, insulin, and the superoxide dismutase. HFD enriched pathways linked to adipocytokine signaling in brown adipose tissue, while PM2.5 impacted genes associated with fat formation. Both exposures downregulated protein metabolism pathways in white adipose tissue and activated stress-response pathways in cardiac tissue. Peroxisome proliferator-activated receptor and AMP-activated protein kinase signaling pathways in the liver were enriched, influencing non-alcoholic fatty liver disease. These findings highlight that combined exposure to HFD and PM2.5 amplifies body weight gain, oxidative stress, and metabolic dysfunction, suggesting a synergistic interaction with significant implications for metabolic health.

Metabolite correlation permutation after mice acute exposure to PM2.5: Holistic exploration of toxicometabolomics by network analysis

Many environmental toxicants can cause systemic effects, such as fine particulate matter (PM2.5), which can penetrate the respiratory barrier and induce effects in multiple tissues. Although metabolomics has been used to identify biomarkers for PM2.5, its multi-tissue toxicology has not yet been explored holistically. Our objective is to explore PM2.5 induced metabolic alterations and unveil the intra-tissue responses along with inter-tissue communicational effects. In this study, following a single intratracheal instillation of multiple doses (0, 25, and 150 μg as the control, low, and high dose), non-targeted metabolomics was employed to evaluate the metabolic impact of PM2.5 across multiple tissues. PM2.5 induced tissue-specific and dose-dependent disturbances of metabolites and their pathways. The remarkable increase of both intra- and inter-tissue correlations was observed, with emphasis on the metabolism connectivity among lung, spleen, and heart; the tissues' functional specificity has marked their toxic modes. Beyond the inter-status comparison of the metabolite fold-changes, the current correlation network built on intra-status can offer additional insights into how the multiple tissues and their metabolites coordinately change in response to external stimuli such as PM2.5 exposure.

Real-ambient particulate matter exposure-induced FGFR1 methylation contributes to cardiac dysfunction via lipid metabolism disruption

Particulate matter (PM)-induced cardiometabolic disorder contributes to the progression of cardiac diseases, but its epigenetic mechanisms are largely unknown. This study used bioinformatic analysis, in vivo and in vitro multiple models to investigate the role of PM-induced cardiac fibroblast growth factor 1 (FGFR1) methylation and its impact on cardiomyocyte lipid metabolic disruption. Bioinformatic analysis revealed that FGFR1 was associated with cardiac pathologies, mitochondrial function and metabolism, supporting the possibility that FGFR1 may play regulatory roles in PM-induced cardiac functional impairment and lipid metabolism disorders. Individually ventilated cage (IVC)-based real-ambient PM exposure system mouse models were used to expose C57/BL6 mice for six and fifteen weeks. The results showed that PM induced cardiac lipid metabolism disorder, DNA nucleotide methyltransferases (DNMTs) alterations and FGFR1 expression declines in mouse heart. Lipidomics analysis revealed that carnitines, phosphoglycerides and lysophosphoglycerides were most significantly affected by PM exposure. At the cellular level, AC16 cells treated with FGFR1 inhibitor (PD173074) led to impaired mitochondrial and metabolic functions in cardiomyocytes. Inhibition of DNA methylation in cells by 5-AZA partially restored the FGFR1 expression, ameliorated cardiomyocyte injury and mitochondrial functions. These changes involved alterations in AMP-activated protein kinase (AMPK)-peroxisome proliferator activated receptors gamma, coactivator 1 alpha (PGC1α) pathways. Bisulfite sequencing PCR (BSP) and DNA methylation specific PCR (MSP) confirmed that PM exposure induced FGFR1 gene promoter region methylation. These results suggested that, by inducing FGFR1 methylation, PM exposure would affect cardiac injury and deranged lipid metabolism. Overexpression of FGFR1 in mouse heart using adeno-associated virus 9 (AAV9) effectively alleviated PM-induced cardiac impairment and metabolic disorder. Our findings identified that FGFR1 methylation might be one of the potential indicators for PM-induced cardiac mitochondrial and metabolic dysfunction, providing novel insights into underlying PM-related cardiotoxic mechanisms.

Fine particulate matter induces adipose tissue expansion and weight gain: Pathophysiology

Dysregulations in energy balance represent a major driver of obesity. Recent evidence suggests that environmental factors also play a pivotal role in inducing weight gain. Chronic exposure to fine particulate matter (PM_2.5 ) is associated with white adipose tissue (WAT) expansion in animals and higher rates of obesity in humans. This review discusses metabolic adaptions in central and peripheral tissues that promote energy storage and WAT accumulation in PM_2.5 -exposed animals and humans. Chronic PM_2.5 exposure produces inflammation and leptin resistance in the hypothalamus, decreasing energy expenditure and increasing food intake. PM_2.5 promotes the conversion of brown adipocytes toward the white phenotype, resulting in decreased energy expenditure. The development of inflammation in WAT can stimulate adipogenesis and hampers catecholamine-induced lipolysis. PM_2.5 exposure affects the thyroid, reducing the release of thyroxine and tetraiodothyronine. In addition, PM_2.5 exposure compromises skeletal muscle fitness by inhibiting Nitric oxide (NO)-dependent microvessel dilation and impairing mitochondrial oxidative capacity, with negative effects on energy expenditure. This evidence suggests that pathological alterations in the hypothalamus, brown adipose tissue, WAT, thyroid, and skeletal muscle can alter energy homeostasis, increasing lipid storage and weight gain in PM_2.5 -exposed animals and humans. Further studies will enrich this pathophysiological model.

Air pollution combined with high-fat feeding aggravates metabolic and cardiovascular diseases: A dangerous, oxidative, and immune-inflammatory association

Obesity and particulate air pollutant (PM_2.5) are important risk factors for cardiometabolic diseases. PM_2.5 exacerbates insulin resistance and lipid ectopic deposition in obese animals. The inorganic fraction of PM_2.5, the Residual Oil Fly Ash (ROFA), is related to cardiovascular events, by enhancing the generation of reactive species, inflammatory cytokines, and leukocyte activation. However, the synergistic effects of ROFA and a high-fat diet (HFD) are still poorly described, and the studies were mainly conducted with males.

AIMS

To investigate if ROFA could potentiate the cardiometabolic effects of diet-induced obesity in female rats.

MATERIAL AND METHODS

Wistar female rats were divided into four groups: Control (n = 6), Polluted (n = 6), HFD (n = 6), and HFD + Polluted (n = 6). HFD and HFD + Polluted received a high-fat diet (HFD) (58.3 % as fats), whilst Control and Polluted groups received a standard diet (Nuvilab CR-1). In addition, Polluted and HFD + Polluted groups received intranasal instillation of ROFA (250 μg/50 μL), while Control and HFD groups received saline solution (50 μL) daily, five days per week. Both interventions occurred 24 weeks after the animals were euthanized.

KEY FINDINGS

HFD combined with ROFA exposure impaired lipid profile challenged systemic and cardiac antioxidant defense, and presented a synergistic effect in inducing an immune-inflammatory condition. We found that the lipid profile disturbance is associated with HFD-induced hepatic, but not cardiac, deposition of triglycerides in female animals.

SIGNIFICANCE

Our results support the hypothesis that ROFA exposure combined with bad feeding can exacerbate metabolic and cardiovascular diseases.

Adult exposure of atrazine alone or in combination with carbohydrate diet hastens the onset/progression of type 2 diabetes in Drosophila

AIM

The combined impact of traditional and non-traditional risk factors of type 2 diabetes (T2D) on the development and progression of insulin resistance and associated complications is poorly understood. Therefore, we assessed the effect of moderately rich sugar diet coupled with environmental chemical exposure on the development and progression of T2D using Drosophila as a model organism.

MAIN METHODS

We reared newly eclosed Drosophila males on a diet containing atrazine (20 μg/ml; non-traditional risk factor) and/or moderately high sucrose (0.5 M/1 M; to mimic binge eating, Traditional risk factor) for 20-30 days. Subsequently, we assessed diabetic parameters, oxidative stress parameters and also the abundance of advanced glycation end products (AGEs) along with their receptor (RAGE) in these flies. For diabetic cardiomyopathy, we examined the pericardin (tissue fibrosis marker) level in Drosophila heart.

KEY FINDINGS

Flies reared on 20 μg/ml atrazine alone showed T2D hallmarks at 30 days. In contrast, flies reared on 0.5 M sucrose+ 20 μg/ml atrazine showed insulin resistance characterized by hyperglycemia and increased Drosophila insulin-like peptides along with reduced insulin signaling at 20 days, similar to those reared on high sucrose diet. In addition, both groups had high levels of oxidative stress and showed starvation response (converting triglycerides into fatty acids). Alarmingly, flies fed with sucrose+atrazine for 20 and 30 days had elevated pericardin in heart tissues, indicating early onset of diabetic complications such as cardiomyopathy.

SIGNIFICANCE

Lifestyle-chemical exposure synergistically impairs glucose metabolism, affects organisms' redox state and leads to the early onset of T2D and associated complications like cardiomyopathy.

Oral Administration of Omega-3 Fatty Acids Attenuates Lung Injury Caused by PM2.5 Respiratory Inhalation Simply and Feasibly In Vivo

For developing an effective interventional approach and treatment modality for PM2.5, the effects of omega-3 fatty acids on alleviating inflammation and attenuating lung injury induced by inhalation exposure of PM2.5 were assessed in murine models. We found that daily oral administration of the active components of omega-3 fatty acids, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) effectively alleviated lung parenchymal lesions, restored normal inflammatory cytokine levels and oxidative stress levels in treating mice exposed to PM2.5 (20 mg/kg) every 3 days for 5 times over a 14-day period. Especially, CT images and the pathological analysis suggested protective effects of DHA and EPA on lung injury. The key molecular mechanism is that DHA and EPA can inhibit the entry and deposition of PM2.5, and block the PM2.5-mediated cytotoxicity, oxidative stress, and inflammation.

Exposure to ambient fine particulate matter impedes the function of spleen in the mouse metabolism of high-fat diet

Epidemiological and experimental evidence has been associating the exposure with ambient fine particulate matter (PM_2.5) with metabolic malfunctions such as obesity and cardiovascular disease. As the blood-filter and the important lymphatic organ, spleen participates in the regulation of metabolic balance. In this work, liquid chromatography-mass spectrometry (LC-MS)-based lipidomics, metabolomics and proteomics were performed to study the effects of PM_2.5 exposure and high-fat diet (HFD) induced obesity on mice spleen. By comparing the differences in lipids, metabolites, and proteins in the spleens from PM_2.5 and HFD treated mice, we discovered the individual and combined effects of the two risk factors. The results showed the PM_2.5 exposure altered energy metabolism of the mice, as evidenced by the upregulation of TCA cycle. In addition, the metabolism of branched-chain amino acids was also significantly changed, which might be related to the preventive function of spleen in lipid metabolism. The PM_2.5-induced metabolic changes in spleen could further aggravate the adverse impacts of HFD on mice, resulting in impeded splenic metabolism of lipids. This study revealed the effects of PM_2.5 and obesity mice spleen, which might be of great significance to public health.

Meteorological Influences on Spatiotemporal Variation of PM2.5 Concentrations in Atmospheric Pollution Transmission Channel Cities of the Beijing-Tianjin-Hebei Region, China

Understanding the spatiotemporal characteristics of PM2.5 concentrations and identifying their associated meteorological factors can provide useful insight for implementing air pollution interventions. In this study, we used daily air quality monitoring data for 28 air pollution transmission channel cities in the Beijing-Tianjin-Hebei region during 2014-2019 to quantify the relative contributions of meteorological factors on spatiotemporal variation in PM2.5 concentration by combining time series and spatial perspectives. The results show that annual mean PM2.5 concentration significantly decreased in 24 of the channel cities from 2014 to 2019, but they all still exceeded the Grade II Chinese Ambient Air Quality Standards (35 μg m-3) in 2019. PM2.5 concentrations exhibited clear spatial agglomeration in the most polluted season, and their spatial pattern changed slightly over time. Meteorological variables accounted for 31.96% of the temporal variation in PM2.5 concentration among the 28 cities during the study period, with minimum temperature and average relative humidity as the most critical factors. Spatially, atmospheric pressure and maximum temperature played a key role in the distribution of PM2.5 concentration in spring and summer, whereas the effect of sunshine hours increased greatly in autumn and winter. These findings highlight the importance of future clean air policy making, but also provide a theoretical support for precise forecasting and prevention of PM2.5 pollution.

Taurine reduction associated with heart dysfunction after real-world PM2.5 exposure in aged mice

Ambient PM_2.5 has been proved to be an independent risk factor for cardiovascular diseases; however, little information is available on the age-dependent effects of PM_2.5 on the cardiovascular system and the underlying mechanisms following chronic exposure. In this study, multi-aged mice were exposed to PM_2.5 via the newly developed real-ambient PM_2.5 exposure system to investigate age-related effects on the heart after long-term exposure. First, the chemical and physical properties of PM_2.5 used in the exposure system were analyzed. The heart rate of conscious mice was recorded, and results showed that exposure of aged mice to PM_2.5 for 26 weeks significantly increased heart rate. Histological analysis and ELISA assays indicated that aged mice were more sensitive to PM_2.5 exposure in terms of inducing cardiac oxidative stress and inflammation. Furthermore, untargeted metabolomics revealed that taurine was involved with the PM_2.5-induced cardiac dysfunction. The reduced taurine concentration in the heart was examined by LC-MS and imaging mass spectrometry; it may be due to the increased p53 expression level, ROS and inflammatory cytokines. These results emphasize the age-dependent effects of PM_2.5 on the cardiovascular system and suggest that taurine may be the novel cardiac effect target for PM_2.5-induced heart dysfunction in the aged.

Dynamic recovery after acute single fine particulate matter exposure in male mice: Effect on lipid deregulation and cardiovascular alterations

Many studies have linked airborne fine particulate matter (PM2.5) exposure to cardiovascular diseases. We performed a time-series analysis to investigate whether the disruption of lipid metabolism recovered or lasted after acute PM2.5 exposure in mice. Targeted lipidomic analysis showed that four major plasma membrane phospholipids along with cholesterol esters (CE) were significantly altered on 7th post-exposure day (PED7), and the alteration reached a peak on PED14. On PED21, the phosphatidylcholine (PC) decrease was more marked than on PED14, and its resurgence was indirectly linked to triglyceride (TG) increase. Homocysteine (HCY), lactate dehydrogenase (LDH), and α-hydroxybutyrate dehydrogenase (α-HBDH) levels increased but glucose levels decreased markedly in a dose- and time-dependent manner throughout the experimental period. Network analysis showed that the lasting lipid deregulation on PED21 correlated to myocardial markers and glucose interruption, during which high-density lipoprotein cholesterol (HDL-C) decreased. The present data implied that the constructional membrane lipids were initially interrupted by PM2.5, and the subsequent rehabilitation resulted in the deregulation of storage lipids; the parallel myocardial and glucose effects may be enhanced by the lasting HDL-C lipid deregulation on PED21. These myocardial and lipidomic events were early indicators of cardiovascular risk, resulting from subsequent exposure to and accumulation of PM2.5.

Application of a real-ambient fine particulate matter exposure system on different animal models

Simulation of fine particulate matter (PM_2.5) exposure is essential for evaluating adverse health effects. In this work, an ambient exposure system that mimicked real atmospheric conditions was installed in Taiyuan, China to study impacts of chronic PM_2.5 exposure on adult and aged mice as well as Sirtuin3 knockout (Sirt3 KO) mice and wild-type (WT) mice. The real-ambient exposure system eliminated the possible artificial effects caused from exposure experiments and maintained the physiochemical characteristics of PM_2.5. The case studies indicated that aged mice exhibited apparent heart dysfunction involving increased heart rate and decreased blood pressure after 17-week of real-ambient PM_2.5 exposure. Meanwhile, 15-week of real-ambient PM_2.5 exposure decreased the heart rate and amounts of associated catecholamines to induce heart failure in Sirt3 KO mice. Additionally, the increased pro-inflammatory cytokines and decreased platelet related indices suggested that inflammation occurred. The changes of biomarkers detected by targeted metabolomics confirmed metabolic disorder in WT and Sirt3 KO mice after exposed to real-ambient PM_2.5. These results indicated that the real-ambient PM_2.5 exposure system could evaluate the risks of certain diseases associated with air pollution and have great potential for supporting the investigations of PM_2.5 effects on other types of rodent models.

Metabolic and Lipid Alterations in Mice Brain Cortex after PM2.5 Exposure

Fine particulate matter (PM_2.5) has been reported to be associated with neurological disorders. However, the effects of PM_2.5 on changes in metabolic and lipid profile of the brain are unclear. In this study, global metabolomics and lipidomics in mice cortex were investigated from the analyses by ultraperformance liquid chromatography-Orbitrap mass spectrometry. The partial least-squares discriminant analysis showed that the metabolite and lipid profiles were significantly altered by PM_2.5 exposure. The changed metabolic pathways including alanine, aspartate, and glutamate metabolism, carnitine metabolism, and glycerophospholipid remodeling pathway were found to be associated with a neurodegenerative process according to their corresponding molecular mechanisms. Our results indicated that PM_2.5 exposure could induce neurological damage.