Traffic-related particulate matter exposure induces nephrotoxicity in vitro and in vivo

Long-term ambient air pollution exposure and renal function and biomarkers of renal disease

BACKGROUND

Despite accumulating evidence of an association between air pollution and renal disease, studies on the association between long-term exposure to air pollution and renal function are still contradictory. This study aimed to investigate this association in a large population with relatively low exposure and with improved estimation of renal function as well as renal injury biomarkers.

METHODS

We performed a cross-sectional analysis in the middle-aged general population participating in the Swedish CardioPulmonary bioImaging Study (SCAPIS; n = 30 154). Individual 10-year exposure to total and locally emitted fine particulate matter (PM2.5), inhalable particulate matter (PM10), and nitrogen oxides (NOx) were modelled using high-resolution dispersion models. Linear regression models were used to estimate associations between exposures and estimated glomerular filtration rate (eGFR, combined creatinine and cystatin C) and serum levels of renal injury biomarkers (KIM-1, MCP-1, IL-6, IL-18, MMP-2, MMP-7, MMP-9, FGF-23, and uric acid), with consideration of potential confounders.

RESULTS

Median long-term PM2.5 exposure was 6.2 µg/m3. Almost all participants had a normal renal function and median eGFR was 99.2 mL/min/1.73 m2. PM2.5 exposure was associated with 1.3% (95% CI 0.6, 2.0) higher eGFR per 2.03 µg/m3 (interquartile range, IQR). PM2.5 exposure was also associated with elevated serum matrix metalloproteinase 2 (MMP-2) concentration, with 7.2% (95% CI 1.9, 12.8) higher MMP-2 per 2.03 µg/m3. There was a tendency towards an association between PM10 and higher levels of uric acid, but no associations were found with the other biomarkers. Associations with other air pollutants were null or inconsistent.

CONCLUSION

In this large general population sample at low exposure levels, we found a surprising association between PM2.5 exposure and a higher renal filtration. It seems unlikely that particle function would improve renal function. However, increased filtration is an early sign of renal injury and may be related to the relatively healthy population at comparatively low exposure levels. Furthermore, PM2.5 exposure was associated with higher serum concentrations of MMP-2, an early indicator of renal and cardiovascular pathology.

Long-term exposure to air pollution and chronic kidney disease-associated mortality-Results from the pooled cohort of the European multicentre ELAPSE-study

Despite the known link between air pollution and cause-specific mortality, its relation to chronic kidney disease (CKD)-associated mortality is understudied. Therefore, we investigated the association between long-term exposure to air pollution and CKD-related mortality in a large multicentre population-based European cohort. Cohort data were linked to local mortality registry data. CKD-death was defined as ICD10 codes N18-N19 or corresponding ICD9 codes. Mean annual exposure at participant's home address was determined with fine spatial resolution exposure models for nitrogen dioxide (NO2), black carbon (BC), ozone (O3), particulate matter ≤2.5 μm (PM2.5) and several elemental constituents of PM2.5. Cox regression models were adjusted for age, sex, cohort, calendar year of recruitment, smoking status, marital status, employment status and neighbourhood mean income. Over a mean follow-up time of 20.4 years, 313 of 289,564 persons died from CKD. Associations were positive for PM2.5 (hazard ratio (HR) with 95% confidence interval (CI) of 1.31 (1.03-1.66) per 5 μg/m3, BC (1.26 (1.03-1.53) per 0.5 × 10- 5/m), NO2 (1.13 (0.93-1.38) per 10 μg/m3) and inverse for O3 (0.71 (0.54-0.93) per 10 μg/m3). Results were robust to further covariate adjustment. Exclusion of the largest sub-cohort contributing 226 cases, led to null associations. Among the elemental constituents, Cu, Fe, K, Ni, S and Zn, representing different sources including traffic, biomass and oil burning and secondary pollutants, were associated with CKD-related mortality. In conclusion, our results suggest an association between air pollution from different sources and CKD-related mortality.

Occupational particle exposure and chronic kidney disease: a cohort study in Swedish construction workers

OBJECTIVES

Increasing epidemiological and experimental evidence suggests that particle exposure is an environmental risk factor for chronic kidney disease (CKD). However, only a few case-control studies have investigated this association in an occupational setting. Hence, our objective was to investigate associations between particle exposure and CKD in a large cohort of Swedish construction workers.

METHODS

We performed a retrospective cohort study in the Swedish Construction Workers' Cohort, recruited 1971-1993 (n=286 089). A job-exposure matrix was used to identify workers exposed to nine different particulate exposures, which were combined into three main categories (inorganic dust and fumes, wood dust and fibres). Incident CKD and start of renal replacement therapy (RRT) were obtained from validated national registries until 2021 and analysed using adjusted Cox proportional hazards models.

RESULTS

Exposure to inorganic dust and fumes was associated with an increased risk of CKD and RRT during working age (adjusted HR for CKD at age <65 years 1.15, 95% CI 1.05 to 1.26). The elevated risk did not persist after retirement age. Exposure to cement dust, concrete dust and diesel exhaust was associated with CKD. Elevated HRs were also found for quartz dust and welding fumes.

CONCLUSIONS

Workers exposed to inorganic particles seem to be at elevated risk of CKD and RRT. Our results are in line with previous evidence of renal effects of ambient air pollution and warrant further efforts to reduce occupational and ambient particle exposure.

Early-life exposure to ambient air pollutants and kidney function in adolescents: a cohort study based on the 'Children of 1997' Hong Kong birth cohort

OBJECTIVES

Air pollution is increasingly linked to impaired kidney function in adults. However, little is known about how early-life exposure to air pollutants affects kidney function in adolescents.

STUDY DESIGN

Cohort study.

METHODS

We leveraged data from the 'Children of 1997' Hong Kong population-representative birth cohort (N = 8327). Residential exposure to average ambient levels of four air pollutants, including inhalable particle (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), and nitrogen monoxide (NO), during in utero, infancy, and childhood periods was estimated using the inverse distance weighting. Kidney function was assessed using estimated glomerular filtration rate (eGFR) calculated from age-adjusted equations for adolescents. Generalized linear regression was used to examine the association of air pollutant exposure in each period with kidney function at 17.6 years. Two-pollutant models tested the robustness of the association.

RESULTS

Of the 3350 participants included, 51.4% were boys. Exposure to PM10 was associated with poorer kidney function. Each interquartile range increment in PM10 was inversely associated with eGFR (β: -2.933, 95% confidence interval -4.677 to -1.189) in utero, -2.362 (-3.992 to -0.732) infancy, -2.708 (-4.370 to -1.047) childhood, and -2.828 (-4.409 to -1.247) overall. Exposure to PM10 and SO2in utero had a stronger inverse association with kidney function in males. The associations were robust to PM10 exposure in two-pollutant models.

CONCLUSIONS

Our findings suggest that early-life exposure to ambient PM10 and SO2 is associated with reduced kidney function in adolescents, especially exposure in utero.

Association between ambient PM1 and the prevalence of chronic kidney disease in China: A nationwide study

Particulate of diameter ≤ 1 µm (PM1) presents a novel risk factor of adverse health effects. Nevertheless, the association of PM1 with the risk of chronic kidney disease (CKD) in the general population is not well understood, particularly in regions with high PM1 levels like China. Based on a nationwide representative survey involving 47,204 adults and multi-source ambient air pollution inversion data, the present study evaluated the association of PM1 with CKD prevalence in China. The two-year average PM1, particulate of diameter ≤ 2.5 µm (PM2.5), and PM1-2.5 values were accessed using a satellite-based random forest approach. CKD was defined as estimated glomerular filtration rate < 60 ml/min/1.73 m2 or albuminuria. The results suggested that a 10 μg/m3 rise in PM1 was related to a higher CKD risk (odds ratio [OR], 1.13; 95% confidence interval [CI] 1.08-1.18) and albuminuria (OR, 1.11; 95% CI, 1.05-1.17). The association between PM1 and CKD was more evident among urban populations, older adults, and those without comorbidities such as diabetes or hypertension. Every 1% increase in the PM1/PM2.5 ratio was related to the prevalence of CKD (OR, 1.03; 95% CI, 1.03-1.04), but no significant relationship was found for PM1-2.5. In conclusion, the present study demonstrated long-term exposure to PM1 was associated with an increased risk of CKD in the general population and PM1 might play a leading role in the observed relationship of PM2.5 with the risk of CKD. These findings provide crucial evidence for developing air pollution control strategies to reduce the burden of CKD.

Association of fine particulate matter (PM2.5) exposure and chronic kidney disease outcomes: a systematic review and meta-analysis

Several studies have reported an increased risk of chronic kidney disease (CKD) outcomes after long-term exposure (more than 1 year) to particulate matter with an aerodynamic diameter of ≤ 2.5 µm (PM2.5). However, the conclusions remain inconsistent. Therefore, we conducted this meta-analysis to examine the association between long-term PM2.5 exposure and CKD outcomes. A literature search was conducted in PubMed, Scopus, Cochrane Central Register of Controlled trials, and Embase for relevant studies published until August 10, 2023. The main outcomes were incidence and prevalence of CKD as well as incidence of end-stage kidney disease (ESKD). The random-effect model meta-analyses were used to estimate the risk of each outcome among studies. Twenty two studies were identified, including 14 cohort studies, and 8 cross-sectional studies, with a total of 7,967,388 participants. This meta-analysis revealed that each 10 μg/m3 increment in PM2.5 was significantly associated with increased risks of both incidence and prevalence of CKD [adjusted odds ratio (OR) 1.31 (95% confidence interval (CI) 1.24 to 1.40), adjusted OR 1.31 (95% CI 1.03 to 1.67), respectively]. In addition, the relationship with ESKD incidence is suggestive of increased risk but not conclusive (adjusted OR 1.16; 95% CI 1.00 to 1.36). The incidence and prevalence of CKD outcomes had a consistent association across all subgroups and adjustment variables. Our study observed an association between long-term PM2.5 exposure and the risks of CKD. However, more dedicated studies are required to show causation that warrants urgent action on PM2.5 to mitigate the global burden of CKD.

Associations of multiple air pollutants with kidney function in normal-weight and obese adults and effect modification by free fatty acids

Increasing studies have linked air pollution to kidney dysfunction, however, the associations between the mixture of air pollutants and kidney function and potential effect modifiers remain unclear. We aimed to investigate whether obese adults were more susceptible than normal-weight ones to the joint effects of multiple air pollutants on kidney function and further to explore effect modification by free fatty acids (FFAs). Forty obese and 49 normal-weight adults were recruited from a panel study (252 follow-up visits). Individual exposure levels of air pollutants (PM2.5, PM10, O3, NO2, SO2 and CO) were estimated. Glomerular function (cystatin C (CysC) and estimated glomerular filtration rate (eGFR)) and tubular function (neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1) were evaluated. Plasma levels of FFAs including trans fatty acids (TFAs) and essential fatty acids (EFAs) were quantified using targeted metabolomics. Bayesian kernel machine regression model was applied to estimate the associations between the mixture of air pollutants and kidney function. The results showed significant joint effects of air pollutants on kidney function indicators. In the normal-weight group, the mixture of air pollutants was significantly associated with CysC and eGFRcr-cys when the mixture was at or above its 70 percentile compared with the median, where O3 was identified as the key pollutant. In the obese group, a significantly positive association between the pollutant mixture and NGAL was observed in addition to trends in CysC and eGFRcr-cys, mainly driven by SO2. Interaction analysis suggested that the associations of air pollutants with kidney function were augmented by TFAs in both groups and weakened by EFAs in the normal-weight group. This study highlighted the renal adverse effects of air pollutants and modification of FFAs, which has implications for target prevention for kidney dysfunction associated with air pollution, especially among vulnerable populations.

A review on potential approach for in silico toxicity analysis of respirable fraction of ambient particulate matter

Epidemiological and toxicological studies have shown the adverse effect of ambient particulate matter (PM) on respiratory and cardiovascular systems inside the human body. Various cellular and acellular assays in literature use indicators like ROS generation, cell inflammation, mutagenicity, etc., to assess PM toxicity and associated health effects. The presence of toxic compounds in respirable PM needs detailed studies for proper understanding of absorption, distribution, metabolism, and excretion mechanisms inside the body as it is difficult to accurately imitate or simulate these mechanisms in lab or animal models. The leaching kinetics of the lung fluid, PM composition, retention time, body temperature, etc., are hard to mimic in an artificial experimental setup. Moreover, the PM size fraction also plays an important role. For example, the ultrafine particles may directly enter systemic circulations while coarser PM10 may be trapped and deposited in the tracheo-bronchial region. Hence, interpretation of these results in toxicity models should be done judiciously. Computational models predicting PM toxicity are rare in the literature. The variable composition of PM and lack of proper understanding for their synergistic role inside the body are prime reasons behind it. This review explores different possibilities of in silico modeling and suggests possible approaches for the risk assessment of PM particles. The toxicity testing approach for engineered nanomaterials, drugs, food industries, etc., have also been investigated for application in computing PM toxicity.

Associations of air pollutant concentrations with longitudinal kidney function changes in patients with chronic kidney disease

This longitudinal cohort study investigated the associations of air pollutant exposures, including CO, NO, NO₂, NO_x, O₃, PM₁₀, PM_2.5, and SO₂, with long-term kidney function changes in patients with chronic kidney disease (CKD). We enrolled 447 CKD patients who took part in a universal hospital pre-ESRD care program during 2011-2015. The daily average air pollutant exposures and temperature were estimated for each patient, with different levels of air pollutant concentrations defined by 5-knot and restricted cubic spline function. Predicted annual estimated glomerular filtration (eGFR) slope values by one mixed model were considered as the study outcome. The average age of the study population was 77.1 ± 12.6 years, and the median annual eGFR decreased by 2.1 ml/min/1.73 m² per year from 30 ml/min/1.73 m² at baseline during a mean follow-up time of 3.4 years. The univariable and multivariable analyses revealed no significant linear and non-linear associations between 5-knot air pollutant concentrations and annual eGFR slope. In addition, the visualized spline effect plots show insignificant variation patterns in annual eGFR slope values with increased air pollutant concentrations. These results encourage more extensive studies to clarify the causal relationships and mechanisms of long-term specific air pollutant exposures and longitudinal kidney function change, especially in CKD populations.

Vitamin B ameliorates PM2.5-induced kidney damage by reducing endoplasmic reticulum stress and oxidative stress in pregnant mice and HK-2

As an air pollutant, particulate matters 2.5 (PM_2.5) poses a severe risk to kidney and the mechanism involves oxidative stress and endoplasmic reticulum (ER) stress. As an essential nutrient for human health, Vitamin B performs anti-inflammatory and antioxidant functions. In order to study the effect of Vitamin B on PM_2.5-induced kidney damage during pregnancy, the pregnant mice were divided into the four experimental groups randomly: control group, model group, treatment group and VB group. PM_2.5 was sprayed on the trachea of pregnant mice once each three days for six times from pregnancy until delivery. The model group was given 30μL PM_2.5 suspension of 3.456μg/μL and 10mL/(kg·d) PBS. The treatment group was given 30μL PM_2.5 suspension of 3.456μg/μL and 10mL/(kg·d) Vitamin B. The VB group was given 10mL/(kg·d) Vitamin B and the control group was given the same dose of PBS. Vitamin B was composed of Vitamin B6, Vitamin B12 and folic acid, with final concentrations are 1.14, 0.02 and 0.06mg/mL, respectively. The results showed Vitamin B ameliorated PM_2.5-induced kidney damage such as improving histopathological change, decreasing expressions of Bip and Chop, increasing expressions of Nrf2, HO-1 and Nqo1. In addition, HK-2 cells were used for cell experiments and were divided into the four groups, in which the dosage of PM_2.5 was 75μg/mL for 24h and Vitamin B was 5μL/100μL. The results showed Vitamin B ameliorated PM_2.5-induced HK-2 damage, such as decreasing expressions of Bip, Chop, P47^phox and ROS, increasing expressions of Nrf2, HO-1, Nqo1 and NO. Our findings showed Vitamin B ameliorated PM_2.5-induced kidney damage by reducing ER stress and oxidative stress in pregnant mice and in HK-2.

Toxicological Effects of Fine Particulate Matter (PM2.5): Health Risks and Associated Systemic Injuries-Systematic Review

Previous studies focused on investigating particulate matter with aerodynamic diameter ≤ 2.5 µm (PM2.5) have shown the risk of disease development, and association with increased morbidity and mortality rates. The current review investigate epidemiological and experimental findings from 2016 to 2021, which enabled the systemic overview of PM2.5's toxic impacts on human health. The Web of Science database search used descriptive terms to investigate the interaction among PM2.5 exposure, systemic effects, and COVID-19 disease. Analyzed studies have indicated that cardiovascular and respiratory systems have been extensively investigated and indicated as the main air pollution targets. Nevertheless, PM2.5 reaches other organic systems and harms the renal, neurological, gastrointestinal, and reproductive systems. Pathologies onset and/or get worse due to toxicological effects associated with the exposure to this particle type, since it can trigger several reactions, such as inflammatory responses, oxidative stress generation and genotoxicity. These cellular dysfunctions lead to organ malfunctions, as shown in the current review. In addition, the correlation between COVID-19/Sars-CoV-2 and PM2.5 exposure was also assessed to help better understand the role of atmospheric pollution in the pathophysiology of this disease. Despite the significant number of studies about PM2.5's effects on organic functions, available in the literature, there are still gaps in knowledge about how this particulate matter can hinder human health. The current review aimed to approach the main findings about the effect of PM2.5 exposure on different systems, and demonstrate the likely interaction of COVID-19/Sars-CoV-2 and PM2.5.

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.

Particulate Matter Elevates Ocular Inflammation and Endoplasmic Reticulum Stress in Human Retinal Pigmented Epithelium Cells

Because of their exposure to air, eyes can come into contact with air pollutants such as particulate matter (PM), which may cause severe ocular pathologies. Prolonged ocular PM exposure may increase inflammation and endoplasmic reticulum stress in the retina. Herein, we investigated whether PM exposure induces ocular inflammation and endoplasmic reticulum (ER) stress-related cellular responses in human retinal epithelium-19 (ARPE-19) cells. To understand how PM promotes ocular inflammation, we monitored the activation of the mitogen-activated protein kinase (MAPK)/nuclear factor kappa beta (NFκB) axis and the expression of key inflammatory mRNAs. We also measured the upregulation of signature components for the ER-related unfolded protein response (UPR) pathways, as well as intracellular calcium ([Ca²⁺]_i) levels, as readouts for ER stress induction following PM exposure. Ocular PM exposure significantly elevated the expression of multiple cytokine mRNAs and increased phosphorylation levels of NFκB-MAPK axis in a PM dose-dependent manner. Moreover, incubation with PM significantly increased [Ca²⁺]_i levels and the expression of UPR-related proteins, which indicated ER stress resulting from cell hypoxia, and upregulation of hypoxic adaptation mechanisms such as the ER-associated UPR pathways. Our study demonstrated that ocular PM exposure increased inflammation in ARPE-19 cells, by activating the MAPK/NFκB axis and cytokine mRNA expression, while also inducing ER stress and stress adaptation responses. These findings may provide helpful insight into clinical and non-clinical research examining the role of PM exposure in ocular pathophysiology and delineating its underlying molecular mechanisms.

Dual role of endoplasmic reticulum stress-ATF-6 activation in autophagy and apoptosis induced by cyclic stretch in myoblast

OBJECTIVE

Mandibular growth that is induced by functional appliances is closely associated with skeletal and neuromuscular adaptation. Accumulating evidence has proved that apoptosis and autophagy have a vital role in adaptation process. However, little is known about the underlying mechanisms. This study sought to determine whether ATF-6 is involved in stretch-induced apoptosis and autophagy in myoblast. The study also sought to uncover the potential molecular mechanism.

MATERIALS AND METHODS

Apoptosis was assessed by TUNEL and Annexin V and PI staining. Autophagy was detected by transmission electron microscopy (TEM) analysis and immunofluorescent staining for autophagy-related protein light chain 3 (LC3). Real time-PCR and western blot were performed to evaluate the expression level of mRNA and proteins that were associated with endoplasmic reticulum stress (ERS), autophagy and apoptosis.

RESULTS

Cyclic stretch significantly decreased the cell viability and induced apoptosis and autophagy of myoblasts time-dependently. Stretching stimuli activated ATF-6 pathway and induced ERS-mediated apoptosis. Moreover, using 4-PBA significantly inhibited ERS-related apoptosis, as well as partially decreasing autophagy. In addition, inhibition of autophagy by 3-MA enhanced apoptosis by affecting the expression of CHOP and Bcl-2. However, it had no obvious effects on ERS-related proteins of GRP78 and ATF-6. More importantly, knockdown ATF-6 effectively weakened apoptosis and autophagy. It did so by regulating the expression of Bcl-2, Beclin1 and CHOP, but not cleaved Caspase-12, LC3II and p62 in stretched myoblast.

CONCLUSION

ATF-6 pathway was activated in myoblast by mechanical stretch. ATF-6 may regulate the process of stretch-induced myoblast apoptosis and autophagy via CHOP, Bcl-2 and Beclin1 signaling.

Lactoferrin attenuated urban particulate matter-induced nephrotoxicity by regulating the CSF2/CENPE axis

Several epidemiological studies regarding the adverse effect of air pollution have notably accelerated in recent years. Urban particulate matter (PM) gains access to the respiratory system and translocates into the circulation to affect several tissues, such as the liver and kidneys. Lactoferrin is a substance belonging to the non-heme iron-binding glycoprotein which is present in breast milk and other exocrine fluids. Lactoferrin is protective against many pathophysiological conditions. In the present study, we explored the potential influence of lactoferrin on PM-induced nephrotoxicity. We found that lactoferrin rescued PM-induced cell death but did not affect apoptosis in human kidney cells. Lactoferrin decreased necroptosis and fibrosis but increased autophagy in human kidney cells. Furthermore, the gene expression profiles of PM and lactoferrin were analyzed by RNA sequencing. The transcriptional profiles were uploaded and analyzed by ingenuity pathway analysis software and gene set enrichment analysis. The results showed that the crucial role of the CSF2/CENPE pathway was involved in human kidney cells treated with PM and lactoferrin. In a mouse model, lactoferrin ameliorates PM-induced nephrotoxicity by regulating necroptosis, fibrosis, autophagy and the CSF2/CENPE axis. In summary, these findings showed that lactoferrin could be a novel therapeutic or preventive agent for renal disorders caused by airborne PM pollution.

The impact of PM2.5 on kidney

PM2.5 poses a severe risk to kidneys, inducing kidney function decline, increasing the risk of suffering from chronic kidney diseases and promoting the occurrence and development of various renal tumors. The mechanism of PM2.5-induced renal injury may involve oxidative stress, inflammatory response, and cytotoxicity. This paper elaborated PM2.5-induced kidney damage and the corresponding possible mechanism so as to raise awareness of air pollution and reduce the damage to human body.

Exposure to ambient particulate matter and hyperuricemia: An eight-year prospective cohort study on male traffic officers in China

BACKGROUND AND OBJECTIVES

Studies on the effects of airborne particulates of diameter ≤ 1 µm (PM₁), airborne particulates of diameter ≤ 2.5 µm (PM_2.5) and airborne particulates of diameter ranges from 1 to 2.5 µm (PM_1-2.5) on incidence of hyperuricemia are limited. We aimed to investigate the associations between PM₁, PM_2.5, and PM_1-2.5 and hyperuricemia among male traffic officers.

METHODS

We conducted a prospective cohort study of 1460 traffic officers without hyperuricemia in Guangzhou, China from 2009 to 2016. Exposures of PM₁ and PM_2.5 were estimated with a spatiotemporal model. PM_1-2.5 concentrations were calculated by subtracting PM₁ from PM_2.5 concentrations. Cox's proportional hazards regressions models were used to examine the association between PM₁, PM_2.5, and PM_1-2.5 and hyperuricemia, adjusted for potential confounders. Associations between PM₁, PM_2.5, and PM_1-2.5 and serum uric acid (SUA) levels were evaluated with multiple linear regression models.

RESULTS

Hazard ratios (HRs) and 95% confidence intervals (CIs) of hyperuricemia associated with 10 μg/m³ increment in PM₁, PM_2.5, and PM_1-2.5 were 1.67 (95% CI:1.30-2.36), 1.49 (95% CI: 1.27-1.75), and 2.18 (95% CI: 1.58-3.02), respectively. The SUA concentrations increased by 12.23 μmol/L (95% CI: 5.91-18.56), 6.93 μmol/L (95% CI: 3.02-10.84), and 8.72 μmol/L (95% CI: 0.76-16.68) per 10 μg/m³ increase in PM₁, PM_2.5, and PM_1-2.5, respectively. Stratified analyses indicated the positive associations of PM_2.5 and PM_1-2.5 with SUA levels were stronger in non-smokers, and PM₁, PM_2.5, and PM_1-2.5 with SUA levels were stronger in non-drinkers.

CONCLUSION

Long-term PM₁, PM_2.5, and PM_1-2.5 exposures may increase the risk of hyperuricemia and elevate SUA levels among male traffic officers, especially in non-smokers and non-drinkers.

Oxidative Stress and Mitochondrial Dysfunction in Chronic Kidney Disease

The kidney contains many mitochondria that generate ATP to provide energy for cellular processes. Oxidative stress injury can be caused by impaired mitochondria with excessive levels of reactive oxygen species. Accumulating evidence has indicated a relationship between oxidative stress and kidney diseases, and revealed new insights into mitochondria-targeted therapeutics for renal injury. Improving mitochondrial homeostasis, increasing mitochondrial biogenesis, and balancing mitochondrial turnover has the potential to protect renal function against oxidative stress. Although there are some reviews that addressed this issue, the articles summarizing the relationship between mitochondria-targeted effects and the risk factors of renal failure are still few. In this review, we integrate recent studies on oxidative stress and mitochondrial function in kidney diseases, especially chronic kidney disease. We organized the causes and risk factors of oxidative stress in the kidneys based in their mitochondria-targeted effects. This review also listed the possible candidates for clinical therapeutics of kidney diseases by modulating mitochondrial function.

Associations between short-term exposure of ambient particulate matter and hemodialysis patients death: A nationwide, longitudinal case-control study in China

BACKGROUND

Long-term exposure to particulate air pollutants can lead to an increase in mortality of hemodialysis patients, but evidence of mortality risk with short-term exposure to ambient particulate matter is lacking. This study aimed to estimate the association of short-term exposure to ambient particulate matter across a wide range of concentrations with hemodialysis patients mortality.

METHODS

We performed a time-stratified case-crossover study to estimate the association between short-term exposures to PM_2.5 and PM₁₀ and mortality of hemodialysis patients. The study included 18,114 hemodialysis death case from 279 hospitals in 41 cities since 2013. Daily particulate matter exposures were calculated by the inverse distance-weighted model based on each case's dialysis center address. Conditional logistic regression were implemented to quantify exposure-response associations. The sensitivity analysis mainly explored the lag effect of particulate matter.

RESULTS

During the study period, there were 18,114 case days and 61,726 control days. Of all case and control days, average PM_2.5 and PM₁₀ levels were 43.98 μg/m³ and 70.86 μg/m³, respectively. Each short-term increase of 10 μg/m³ in PM_2.5 and PM₁₀ were statistically significantly associated with a relative increase of 1.07 % (95 % confidence interval [CI]: 0.99 % - 1.15 %) and 0.89 % (95 % CI: 0.84 % - 0.94 %) in daily mortality rate of hemodialysis patients, respectively. There was no evidence of a threshold in the exposure-response relationship. The mean of daily exposure on the same day of death and one-day prior (Lag 01 Day) was the most plausible exposure time window.

CONCLUSIONS

This study confirms that short-term exposure to particulate matter leads to increased mortality in hemodialysis patients. Policy makers and public health practices have a clear and urgent opportunity to pass air quality control policies that care for hemodialysis populations and incorporate air quality into the daily medical management of hemodialysis patients.

Toxicity mechanism of nanomaterials: Focus on endoplasmic reticulum stress

Over the years, although the broad application of nanomaterials has not brought convenience to people's life, growing concern surrounds their safety. Recently, much emphasis has been placed on exploring the toxicity mechanism of nanoparticles. Currently established toxic mechanisms include oxidative stress, inflammatory response, autophagy, and DNA damage. In recent years, endoplasmic reticulum stress (ERS) has gained widespread attention as another toxic mechanism of nanomaterials. It is widely acknowledged that the endoplasmic reticulum (ER) is an important site for protein synthesis, and lipids and Ca⁺ storage, playing an esseential role in the normal operation of the body functions. When the body's internal environment is damaged, the structure and function of the endoplasmic reticulum are destroyed, leading to a series of biological reactions called endoplasmic reticulum stress (ERS.) This paper reviews the mechanism of ERS in nanomaterial-associated toxicity. The process of ERS and its related unfolded protein response were briefly introduced, summarizing the factors affecting the nanoparticle ability to induce ERS and expounding on the changes of ER morphology after exposure to nanoparticles. Finally, the specific role and molecular mechanism of ERS under the action of different nanoparticles were comprehensively analyzed, including the relationship between ERS and inflammation, oxidative stress, lipid metabolism and apoptosis. This review provides a foothold for future studies on the toxic mechanism of nanoparticles, and provides novel insights into the safe application of nanoparticles and the treatment of diseases.

Associations among prenatal PM2.5, birth weight, and renal function

BACKGROUND

Low birth weight has long-term health effects, including neurodevelopmental delays, cardiovascular diseases, and type 2 diabetes, through epigenetic changes and modifications. Numerous studies have identified that PM_2.5 is associated with low birth weight. However, the association between PM_2.5 and renal function, as well as the mediated effect of renal function on the association between prenatal PM_2.5 and birth weight are still under-recognized.

METHODS

A total of 8969 singleton live births born in 2015-2019 were included in this study. The inverse distance weighting method was applied to interpolate and calculate the average exposure to PM_2.5 during pregnancy for each pregnant woman. The multiple linear regression model was used to shed light on the associations among prenatal PM_2.5, birth weight, and renal function. In addition, the mediation analysis was performed to figure out the mediated effect of renal function on the association between prenatal PM_2.5 and birth weight, and the proportion of mediated effect = (indirect effect/total effect) × 100%.

RESULTS

Per 10 μg/m³ increment of prenatal PM_2.5 was associated with 8.98 g (95% CI: -16.94 to -1.02) decrease of birth weight, 0.49 (95% CI: -0.73 to -0.26) ml/min/1.73 m² decrease of glomerular filtration rate (GFR), 0.03 (95% CI: 0.01-0.05) mmol/L increase of blood urea nitrogen (BUN), and 2.29 (95% CI: 0.86-3.72) μmol/L increase of uric acid (UA) after adjusting for the sociodemographic covariates, disease-related covariates and meteorological factors. Besides, the mediated effects of GFR and BUN on the association between prenatal PM_2.5 and birth weight were 5.02% and 14.96%, but there was no significant mediated effect being identified in UA.

CONCLUSION

Prenatal PM_2.5 is related to reduced birth weight and impaired renal function. Renal function plays a partial role in the association between prenatal PM_2.5 and birth weight. Appropriate guidelines should be formulated by the concerned authorities, and adequate efforts should be made to mitigate the detrimental health effects of PM_2.5.

A protective role of autophagy in fine airborne particulate matter-induced apoptosis in LN-229 cells

Air pollution is a public health threat and global epidemiological studies have shown that ambient air pollutants are closely related to various poor health conditions, including neurodegenerative diseases. Here, we evaluated the toxic effects and the underlying mechanisms of fine airborne particulate matter (PM2.5) on human glioblastoma LN-229 cells. Our results showed that exposure of LN-229 cells to PM2.5 (≥ 200 μg/mL) significantly reduced cell viability. PM2.5 exposure increased autophagy, apoptosis, and ROS production in the cells. Pre-treatment with a ROS scavenger, catalase, or depletion of mtDNA (ρ0 cells) abolished PM2.5-induced autophagy and apoptosis. PM2.5 exposure also activated MAPK signals in cells, which were blocked by catalase pre-treatment or mtDNA depletion. Furthermore, inhibition of JNK, but not ERK1/2 or p38, attenuated PM2.5-induced autophagy and apoptosis in cells. Finally, suppression of autophagy with Bafilomycin A1 or Beclin 1 siRNA exacerbated PM2.5-induced apoptosis, indicating a protective role of autophagy against PM2.5-induced apoptosis. Our results demonstrated that exposure of LN-229 cells to PM2.5 caused autophagy and apoptosis through PM2.5-induced ROS generation, mainly by mitochondria, and JNK activation. Autophagy may have a transient protective response in PM2.5-induced apoptosis. These findings have important implications for understanding the potential neurotoxicity of PM2.5.

Ambient particulate matter exposure plus a high-fat diet exacerbate renal injury by activating the NLRP3 inflammasome and TGF-β1/Smad2 signaling pathway in mice

BACKGROUND

Chronic kidney disease (CKD) is a public health problem of which the prevalence is increasing worldwide. Several studies have reported that ambient particulate matter (PM) causes kidney injury, which may be related to the risk of CKD. However, the underlying molecular mechanisms have not been fully clarified. In addition, whether a high-fat diet (HFD) could exacerbate ambient PM-induced nephrotoxicity has not been evaluated. This study aimed to investigate the combined effect of ambient PM and a HFD on renal injury.

METHODS AND RESULTS

Male C57BL/6 J mice were fed either a normal diet or a HFD and exposed to filtered air (FA) or particulate matter (PM) for 18 weeks. In the present study, we observed that renal function changed (serum blood urea nitrogen and serum creatinine), and exposure to PM and a HFD caused a synergistic effect on renal injury. Histopathological analysis showed that PM exposure induced renal fibrosis in mice, and combined exposure to PM and a HFD exacerbated these adverse effects. Moreover, ambient PM exposure activated the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome and increased the inflammatory response, as indicated by the increases in interleukin-1β, interleukin-6 and tumor necrosis factor-α in the serum and kidney, as well as the upregulation of specific renal fibrosis-related markers (transforming growth factor-β1 and p-Smad2) in the kidney tissues of mice. Furthermore, combined exposure to PM and a HFD augmented these changes in the kidney. In vitro, inhibition of the NLRP3 inflammasome by MCC950 (an inhibitor of NLRP3) reduced the levels of proinflammatory cytokines and the expression of transforming growth factor-β1 and p-Smad2 in HK-2 cells.

CONCLUSION

Taken together, our data indicated that PM exposure caused renal inflammation and induced profibrotic effects on the kidney, and combined exposure to ambient PM and a HFD exacerbated renal injury, which may involve activation of the NLRP3 inflammasome and the TGF-β1/Smad2 signaling pathway.

Effects of PM2.5 and its constituents on hemoglobin during the third trimester in pregnant women

Anemia has been a public health issue evoking global concern, and the low hemoglobin (Hb) concentration links to adverse pregnancy outcomes. However, the associations of PM_2.5 and its constituents with Hb and anemia in pregnant women remain unclear. In this retrospective birth cohort study, 7932 pregnant women who delivered in the First Affiliated Hospital of Xi'an Jiaotong University from 2015 to 2018 were included. The Hb during the third trimester in pregnant women was assessed before delivery. PM_2.5 and its constituents (BC, NH₄⁺, NO₃^-, OM, SO₄^2-, and Dust) during pregnancy were retrieved from the V4.CH.03 product constructed by the Atmospheric Composition Analysis Group. Generalized linear regression model was applied to investigate the effects of PM_2.5 and its constituents on Hb and anemia during the third trimester in pregnant women. The means and standard deviations of PM_2.5, BC, NH₄⁺, NO₃^-, OM, SO₄^2-, and Dust were 69.56 (15.24), 10.02 (2.72), 8.11 (1.77), 14.96 (5.42), 15.36 (4.11), 10.08 (1.20), and 10.98 (1.85) μg/m³, respectively. Per IQR increase (μg/m³) of PM_2.5, BC, NO₃^-, and OM linked to - 0.75 (- 1.50, - 0.01), - 0.85 (- 1.65, - 0.04), - 0.79 (- 1.56, - 0.03), and - 0.73 (- 1.44, - 0.03) g/L decrease of Hb during the third trimester in multiparous pregnant women, but not for NH₄⁺, SO₄^2-, Dust, and primiparous pregnant women. PM_2.5 and its constituents had no significant association with anemia, except for Dust (OR: 0.90, 95% CI: 0.82, 0.99, per IQR increase) in primiparous pregnant women. Besides, SO4^2- was of lag effects on Hb and anemia in multiparous pregnant women. Moreover, non-linear associations were found among PM_2.5 and its constituents, Hb, and anemia. Therefore, exposure to PM_2.5 and some constituents of PM_2.5 was associated with reduced Hb level during the third trimester in multiparous pregnant women. Related departments and pregnant women should take targeted actions to eliminate the detrimental effects of PM_2.5 and its constituents on pregnancy outcomes.

Long-Term Exposure to Fine Particulate Matter and the Deterioration of Estimated Glomerular Filtration Rate: A Cohort Study in Patients With Pre-End-Stage Renal Disease

Limited literature has explored the effect of air pollutants on chronic kidney disease (CKD) progression, especially for patients with pre-end-stage renal disease (pre-ESRD). In this study, we reported the linear and nonlinear relationships of air pollutants of particles with diameter <2.5 μm (PM2.5) and nitrogen dioxide (NO2) with estimated glomerular filtration rate (eGFR) deterioration after adjusting for smoking status and other traditional clinical factors. This study adopted a retrospective cohort of patients with stage 3b to stage 5 CKD (N = 11,479) from Taichung Veterans General Hospital during January 2006 to December 2020. The eGFR deterioration was defined as a decline in eGFR > 5 ml/min/1.73 m2/year. Hybrid kriging/land-use regression models were used to estimate the individual exposure levels of PM2.5 and NO2. The relationships of air pollutants with eGFR deterioration were evaluated using Cox proportional hazard models. After adjusting for smoking status, baseline eGFR stages, and other traditional clinical factors, the risk of eGFR deterioration was found to increase with increasing PM2.5 and NO2 level (p < 0.0001 and p = 0.041, respectively), especially for those exposed to PM2.5 ≥ 31.44 μg/m3 or NO2 ≥ 15.00 ppb. Similar results were also found in the two-pollutant models. Nonlinear dose-response relationships of eGFR deterioration were observed for concentrations of 26.11 μg/m3 for PM2.5 and 15.06 ppb for NO2. In conclusion, linear and nonlinear associations between PM2.5 and NO2 levels and the incidence risk of eGFR deterioration were observed in patients with pre-ESRD.

The biomechanistic aspects of renal cortical injury induced by diesel exhaust particles in rats and the renoprotective contribution of quercetin pretreatment: Histological and biochemical study

Although several studies have reported a toxic effect of diesel exhaust particles (DEP) exposure on the kidney tissues, the involvement of autophagy/NF-kB signaling as encountered mechanisms and the protective effects of a natural flavonoid, quercetin on DEP remains unclear. Thirty-two albino rats were divided as control, quercetin-treated (60 mg/kg, oral), DEP-exposed (0.5 mg/kg, intra-tracheal), and quercetin/DEP-exposed groups. Specimens of the renal cortex were subjected to histo-biochemical study and immunohistochemical analysis using anti-NF-kB, and anti-LC3β antibodies followed by morphometric and statistical analyses. The expression level of autophagy genes was quantitatively evaluated using RT-PCR, as well. The DEP-exposed rats showed an elevation in the renal tissue levels of MDA and a decrease in the catalase and superoxide dismutase (p < .05). Histologically, there were cytoplasmic vacuolar changes in the lining cells of the renal tubules, glomerular atrophy, and vascular congestion. In addition, renal inflammation was evident as confirmed by the increased NF-kB immunoexpression. Moreover, the gene expression of Becn1, ATG5, and LC3β increased (p <. 0) due to DEP exposure. Conversely, quercetin pretreatment improved these renal histo-biochemical alterations (p < .05) and regulated autophagy/NF-kB pathways. Overall, the study proved the renal toxicity mediated by DEP exposure via precipitating renal inflammation, autophagy activation, and oxidative stress. Quercetin pretreatment could antagonize such machinery to protect the kidney against DEP.

Short-term Exposure to Air Pollution and Attributable Risk of Kidney Diseases: A Nationwide Time-series Study

BACKGROUND

Several studies have shown that long-term exposure to air pollution is associated with reduced kidney function. However, less is known about effects of short-term exposure to air pollution on kidney disease aggravation and resultant emergency room (ER) burden. This study aimed to estimate excess ER visits attributable to short-term air pollution and to provide evidence relevant to air pollution standards to protect kidney patients.

METHODS

We conducted time-series analysis using National Health Insurance data covering all persons in South Korea (2003-2013). We collected daily data for air pollutants (particulate matter ≤10 µm [PM10], ozone [O3], carbon monoxide [CO], and sulfur dioxide [SO2]) and ER visits for total kidney and urinary system disease, acute kidney injury (AKI), and chronic kidney disease (CKD). We performed a two-stage time-series analysis to estimate excess ER visits attributable to air pollution by first calculating estimates for each of 16 regions, and then generating an overall estimate.

RESULTS

For all kidney and urinary disease (902,043 cases), excess ER visits attributable to air pollution existed for all pollutants studied. For AKI (76,330 cases), we estimated the highest impact on excess ER visits from O3, while for CKD (210,929 cases), the impacts of CO and SO2 were the highest. The associations between air pollution and kidney ER visits existed for days with air pollution concentrations below current World Health Organization guidelines.

CONCLUSION

This study provides quantitative estimates of ER burdens attributable to air pollution. Results are consistent with the hypothesis that stricter air quality standards benefit kidney patients.

Role of air pollution in chronic kidney disease: an update on evidence, mechanisms and mitigation strategies

Air pollution results from a variable and complex mixture of harmful gases and suspended particles and is the most worrisome of all environmental hazards. It is implicated in several non -communicable diseases and is recognized to be a public health problem. Though the initial exposure to air pollution is through the respiratory system, kidneys are thought to be exposed to higher concentrations owing to their filtration function. Chronic kidney disease is the insidious end result of several disease processes which cumulatively form a large healthcare burden, particularly in low- and middle-income countries. There is a growing body of evidence that air pollution may be a contributing factor that leads to CKD by not only its direct effects, but can also compound the effect of other factors/diseases causing kidney injury. PM_2.5 exposure particularly has been implicated, although there is some evidence regarding other air pollutants as well. These pollutants are thought to act on kidneys through several interlinked systemic pathways and mechanisms which individually and collectively damage the nephrons. Long-term exposures seem to gradually diminish renal function and lead to end-stage renal disease. A thorough understanding of the mechanism of kidney injury is the key for formulating and implementing effective strategies for reducing this burden. Maintaining the air quality, promoting education, improving health quality and promotion of targeted nephroprotective measures through effective policy and research support are required in addressing this global public health problem.

Particulate Matter Promotes Melanin Production through Endoplasmic Reticulum Stress‒Mediated IRE1α Signaling

Particulate matter (PM) is believed to be related to cardiovascular and respiratory diseases. The skin is also known to be affected by PM exposure as a result of skin barrier dysfunction, cutaneous inflammation, and apoptotic cell death. Epidemiological studies have suggested that PM is related to pigment spots. Recently, diesel exhaust particles are reported to cause a tanning response mediated by oxidative stress. However, the direct effects of PM on melanogenesis and the related mechanisms have not yet been clarified. Our study showed that PM can increase melanin production in melanocyte, mouse skin, and human skin models. RNA-sequencing analyses of melanocytes revealed that the expressions of unfolded protein response molecules were increased after PM exposure. In particular, IRE1α signaling pathway, which was consistently upregulated, was related to PM-triggered melanogenesis. In addition, PM-induced melanogenesis was abrogated by an IRE1α inhibitor. Therefore, our findings corroborate previous findings in melanocytes and in mouse and human models and also illuminate the involvement of the IRE1α pathway as a mechanism of PM-induced melanogenesis.

Emerging role of air pollution in chronic kidney disease

Chronic kidney disease (CKD), a global disease burden related to high rates of incidence and mortality, manifests as progressive and irretrievable nephron loss and decreased kidney regeneration capacity. Emerging studies have suggested that exposure to air pollution is closely relevant to increased risk of CKD, CKD progression and end-stage kidney disease (ESKD). Inhaled airborne particles may cause vascular injury, intraglomerular hypertension, or glomerulosclerosis through non-hemodynamic and hemodynamic factors with multiple complex interactions. The mechanisms linking air pollutants exposure to CKD include elevated blood pressure, worsening oxidative stress and inflammatory response, DNA damage and abnormal metabolic changes to aggravate kidney damage. In the present review, we will discuss the epidemiologic observations linking air pollutants exposure to the incidence and progression of CKD. Then, we elaborate the potential roles of several air pollutants including particulate matter and gaseous co-pollutants, environmental tobacco smoke, and gaseous heavy metals in its pathogenesis. Finally, this review outlines the latent effect of air pollution in ESKD patients undergoing dialysis or renal transplant, kidney cancer and other kidney diseases. The information obtained may be beneficial for further elucidating the pathogenesis of CKD and making proper preventive strategies for this disease.

Toxic effect of cooking oil fume (COF) on lungs: Evidence of endoplasmic reticulum stress in rat

BACKGROUND

Cooking oil fumes (COF) is one of the primary sources of indoor air pollution in China, which is associated with respiratory diseases such as acute lung injury and lung cancer. However, evidence of COF toxic effect was few.

OBJECTIVES

The research was aimed to investigate the toxic effect and the underlying mechanisms induced by COF.

METHODS

The female Wistar rats were randomly divided into several groups, including control group, COF exposure group and VE protection group, and instilled intratracheally with different COF suspensions (0.2, 2, 20 mg/kg) or saline once every 3 days for 30 days. After 24 h of final exposure, all rat were anesthetic euthanasia to draw materials. The alveolar lavage fluid (BALF) was for inflammatory cell count. The lung homogenate was to determine the biochemical indexes such as oxidative stress, apoptosis factors, carcinogenic toxicity and endoplasmic reticulum (ER) stress. The left lung was made for immunohistochemical and histopathological analysis.

RESULTS

The results showed that the levels of oxidative stress (ROS), apoptosis factors (NF-κB), carcinogenic toxicity (P53 and 8-OhdG), ER stress (IRE-1α and Caspase-12) in 2 mg/kg and 20 mg/kg COF exposure groups were significantly increased compared with the saline groups. The above pathological changes were improved after vitamin E (VE) supplementation. In addition, the immunohistochemical and histopathological analysis found the same trend.

CONCLUSION

The COF had health risk of heredity and potential carcinogenicity. Besides, COFs can not only induce oxidative stress, but also induce ER stress in lung and airway epithelial cells of female rats through the unfolded protein reaction (UPR) pathway. It revealed that the oxidative stress and ER stress interacted in aggravating lung injury. VE could effectively alleviate the lung injury causing by COF exposure.

Micro- and Nanosized Substances Cause Different Autophagy-Related Responses

With rapid industrialization, humans produce an increasing number of products. The composition of these products is usually decomposed. However, some substances are not easily broken down and gradually become environmental pollutants. In addition, these substances may cause bioaccumulation, since the substances can be fragmented into micro- and nanoparticles. These particles or their interactions with other toxic matter circulate in humans via the food chain or air. Whether these micro- and nanoparticles interfere with extracellular vesicles (EVs) due to their similar sizes is unclear. Micro- and nanoparticles (MSs and NSs) induce several cell responses and are engulfed by cells depending on their size, for example, particulate matter with a diameter ≤2.5 μm (PM2.5). Autophagy is a mechanism by which pathogens are destroyed in cells. Some artificial materials are not easily decomposed in organisms. How do these cells or tissues respond? In addition, autophagy operates through two pathways (increasing cell death or cell survival) in tumorigenesis. Many MSs and NSs have been found that induce autophagy in various cells and tissues. As a result, this review focuses on how these particles interfere with cells and tissues. Here, we review MSs, NSs, and PM2.5, which result in different autophagy-related responses in various tissues or cells.

Lipopolysaccharide-Enhanced Responses against Aryl Hydrocarbon Receptor in FcgRIIb-Deficient Macrophages, a Profound Impact of an Environmental Toxin on a Lupus-Like Mouse Model

Fc gamma receptor IIb (FcgRIIb) is the only inhibitory-FcgR in the FcgR family, and FcgRIIb-deficient (FcgRIIb^−/−) mice develop a lupus-like condition with hyper-responsiveness against several stimulations. The activation of aryl hydrocarbon receptor (Ahr), a cellular environmental sensor, might aggravate activity of the lupus-like condition. As such, 1,4-chrysenequinone (1,4-CQ), an Ahr-activator, alone did not induce supernatant cytokines from macrophages, while the 24 h pre-treatment by lipopolysaccharide (LPS), a representative inflammatory activator, prior to 1,4-CQ activation (LPS/1,4-CQ) predominantly induced macrophage pro-inflammatory responses. Additionally, the responses from FcgRIIb^−/− macrophages were more prominent than wild-type (WT) cells as determined by (i) supernatant cytokines (TNF-α, IL-6, and IL-10), (ii) expression of the inflammation associated genes (NF-κB, aryl hydrocarbon receptor, iNOS, IL-1β and activating-FcgRIV) and cell-surface CD-86 (a biomarker of M1 macrophage polarization), and (iii) cell apoptosis (Annexin V), with the lower inhibitory-FcgRIIb expression. Moreover, 8-week-administration of 1,4-CQ in 8 week old FcgRIIb^−/− mice, a genetic-prone lupus-like model, enhanced lupus characteristics as indicated by anti-dsDNA, serum creatinine, proteinuria, endotoxemia, gut-leakage (FITC-dextran), and glomerular immunoglobulin deposition. In conclusion, an Ahr activation worsened the disease severity in FcgRIIb^−/− mice possibly through the enhanced inflammatory responses. The deficiency of inhibitory-FcgRIIb in these mice, at least in part, prominently enhanced the pro-inflammatory responses. Our data suggest that patients with lupus might be more vulnerable to environmental pollutants.

Nrf2 modulated the restriction of lung function via impairment of intrinsic autophagy upon real-ambient PM2.5 exposure

Compelling studies approve that fine particle matter (PM_2.5) exposure was associated with high risk of respiratory disorders. However, the available data assessing the detailed influence of PM_2.5 on lung was limited. To overcome the difficulty of inhalational PM_2.5 exposure, the real-ambient PM_2.5 exposure system was constructed. The mice were exposed to filtered air (FA) or real-ambient PM_2.5 (PM_2.5), and the adverse effect on lung was determined. Nuclear factor E2-related factor 2 (Nrf2) as a transcription factor, was reported to affect autophagy. Autophagy was proposed as a two-edge sword in respiratory disorders. Here, our data presented that PM_2.5 exposure dramatically reduced the lung function of WT mice rather than Nrf2^-/- mice. Consistently, thickened alveolar walls was observed in WT mice in PM_2.5 exposure group, whereas the histological phenotype of Nrf2^-/- mice exhibited no obvious alteration. Furthermore, PM_2.5 exposure triggered low-grade production of inflammatory profile in WT and Nrf2^-/- mice. Moreover, the protein levels of p62, Beclin1 and LC3B of WT mice rather than Nrf2^-/- mice were also altered in PM_2.5 exposure group. Taken together, the present study applied the real-ambient exposure system, revealed the adverse effect of air pollution on lung, and proposed the underlying mechanism.

Predictive and Preventive Mucosal Communications in Particulate Matter Exposure-Linked Renal Distress

Despite research into the epidemiological link between exposure to particulate matter (PM) and renal disorder, there is limited information available on the etiological complexity and molecular mechanisms. Among the early responsive tissues to PM exposure, the mucosal barrier of the airway and alimentary tract may be a crucial source of pathologic mediators leading to inflammatory renal diseases, including chronic kidney disease (CKD). Given that harmful responses and products in mucosa exposed to PM may enter the circulation and cause adverse outcomes in the kidney, the aim of the present review was to address the impact of PM exposure on the mucosal barrier and the vicious feedback cycle in the mucosal environment. In addition to the PM-induced alteration of mucosal barrier integrity, the microbial community has a pivotal role in the xenobiotic metabolism and individual susceptibility to PM toxicity. The dysbiosis-induced deleterious metabolites of PM and nutrients are introduced systemically via a disrupted mucosal barrier, contributing to renal injuries and pathologic severity. In contrast, the progress of mucosa-associated renal disease is counteracted by endogenous protective responses in the mucosa. Along with direct elimination of the toxic mediators, modulators of the mucosal microbial community should provide a promising platform for mucosa-based personalized interventions against renal disorders caused by air pollution.

Long-Term Exposure to Ambient PM2.5 and Increased Risk of CKD Prevalence in China

BACKGROUND

Fine particulate matter (PM_2.5) is an important environmental risk factor for cardiopulmonary diseases. However, the association between PM_2.5 and risk of CKD remains under-recognized, especially in regions with high levels of PM_2.5, such as China.

METHODS

To explore the association between long-term exposure to ambient PM_2.5 and CKD prevalence in China, we used data from the China National Survey of CKD, which included a representative sample of 47,204 adults. We estimated annual exposure to PM_2.5 before the survey date at each participant's address, using a validated, satellite-based, spatiotemporal model with a 10 km×10 km resolution. Participants with eGFR <60 ml/min per 1.73 m² or albuminuria were defined as having CKD. We used a logistic regression model to estimate the association and analyzed the influence of potential modifiers.

RESULTS

The 2-year mean PM_2.5 concentration was 57.4 μg/m³, with a range from 31.3 to 87.5 μg/m³. An increase of 10 μg/m³ in PM_2.5 was positively associated with CKD prevalence (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.22 to 1.35) and albuminuria (OR, 1.39; 95% CI, 1.32 to 1.47). Effect modification indicated these associations were significantly stronger in urban areas compared with rural areas, in males compared with females, in participants aged <65 years compared with participants aged ≥65 years, and in participants without comorbid diseases compared with those with comorbidities.

CONCLUSIONS

These findings regarding the relationship between long-term exposure to high ambient PM_2.5 levels and CKD in the general Chinese population provide important evidence for policy makers and public health practices to reduce the CKD risk posed by this pollutant.

Neuropathology changed by 3- and 6-months low-level PM2.5 inhalation exposure in spontaneously hypertensive rats

BACKGROUND

Epidemiological evidence has linked fine particulate matter (PM2.5) to neurodegenerative diseases; however, the toxicological evidence remains unclear. The objective of this study was to investigate the effects of PM2.5 on neuropathophysiology in a hypertensive animal model. We examined behavioral alterations (Morris water maze), lipid peroxidation (malondialdehyde (MDA)), tau and autophagy expressions, neuron death, and caspase-3 levels after 3 and 6 months of whole-body exposure to urban PM2.5 in spontaneously hypertensive (SH) rats.

RESULTS

SH rats were exposed to S-, K-, Si-, and Fe-dominated PM2.5 at 8.6 ± 2.5 and 10.8 ± 3.8 μg/m3 for 3 and 6 months, respectively. We observed no significant alterations in the escape latency, distance moved, mean area crossing, mean time spent, or mean swimming velocity after PM2.5 exposure. Notably, levels of MDA had significantly increased in the olfactory bulb, hippocampus, and cortex after 6 months of PM2.5 exposure (p < 0.05). We observed that 3 months of exposure to PM2.5 caused significantly higher expressions of t-tau and p-tau in the olfactory bulb (p < 0.05) but not in other brain regions. Beclin 1 was overexpressed in the hippocampus with 3 months of PM2.5 exposure, but significantly decreased in the cortex with 6 months exposure to PM2.5. Neuron numbers had decreased with caspase-3 activation in the cerebellum, hippocampus, and cortex after 6 months of PM2.5 exposure.

CONCLUSIONS

Chronic exposure to low-level PM2.5 could accelerate the development of neurodegenerative pathologies in subjects with hypertension.

Interactions of particulate matter and pulmonary surfactant: Implications for human health

Particulate matter (PM), which is the primary contributor to air pollution, has become a pervasive global health threat. When PM enters into a respiratory tract, the first body tissues to be directly exposed are the cells of respiratory tissues and pulmonary surfactant. Pulmonary surfactant is a pivotal component to modulate surface tension of alveoli during respiration. Many studies have proved that PM would interact with pulmonary surfactant to affect the alveolar activity, and meanwhile, pulmonary surfactant would be adsorbed to the surface of PM to change the toxic effect of PM. This review focuses on recent studies of the interactions between micro/nanoparticles (synthesized and environmental particles) and pulmonary surfactant (natural surfactant and its models), as well as the health effects caused by PM through a few significant aspects, such as surface properties of PM, including size, surface charge, hydrophobicity, shape, chemical nature, etc. Moreover, in vitro and in vivo studies have shown that PM leads to oxidative stress, inflammatory response, fibrosis, and cancerization in living bodies. By providing a comprehensive picture of PM-surfactant interaction, this review will benefit both researchers for further studies and policy-makers for setting up more appropriate regulations to reduce the adverse effects of PM on public health.

Air pollutants and subsequent risk of chronic kidney disease and end-stage renal disease: A population-based cohort study

Air pollutants have been reported to be a possible risk factor of chronic kidney disease (CKD). However, epidemiologic results regarding acidic gases and CKD have yet to be elucidated. We linked the Taiwan Air Quality Monitoring Database (TAQMD) to the Longitudinal Health Insurance Database. An observational cohort of 161,970 Taiwan citizens who had not been diagnosed with CKD was formed. The concentrations of air pollutant were classified into four levels based on quartile. Multivariable and univariable Cox proportional hazard regression models were used to assess the risk of developing CKD and end-stage renal disease (ESRD). Compared with Q1-level SO2, exposure to the Q4 level was at a 1.46-fold risk of developing CKD (95% confidence interval [CI] = 1.28-1.65) and 1.32-fold risk of ESRD (95% CI = 1.03-1.70). Compared with Q1-level NOx, exposure to the Q4 level was at a 1.39-fold higher risk of developing CKD (95% CI = 1.22-1.58) and 1.70-fold risk of ESRD (95% CI = 1.33-2.18). Compared with Q1-level NO, exposure to the Q4 level was at a 1.48-fold risk of CKD (95% CI = 1.30-1.68) and 1.54-fold risk of ESRD (95% CI = 1.20-1.98). Compared with Q1-level particles <2.5 μm (PM2.5), exposure to the Q4 level were at a 1.74-fold risk of CKD (95% CI = 1.53-1.98) and 1.69-fold risk of ESRD (95% CI = 1.32-2.16). Exposure to particulate and acidic gas air pollution was observed to be associated with an increased risk of CKD and ESRD.

PM2.5 induces autophagy and apoptosis through endoplasmic reticulum stress in human endothelial cells

Endothelial cells integrally form a crucial interface that maintains homeostasis of the cardiovascular system. As a vulnerable target of PM2.5, the underlying mechanisms of endothelial cell damage have yet to be fully elucidated. In the current study, two types of cell death, including autophagy and apoptosis, and an important organelle of the endoplasmic reticulum (ER) were focalized following PM2.5 exposure. As a result, the internalization of PM2.5 has the ability to induce excess ER stress, which is a crucial step for further autophagy and apoptosis in human endothelial cells, as confirmed by the pre-treatment with the inhibitor of ER stress (4-PBA) which effectively mitigates the apoptosis rate and LC3II expression. Intriguingly, crosstalk between ER stress and autophagy demonstrated that ER stress is probably involved in autophagic events, whereas autophagy has no significant effect on ER stress but confer a protective role against PM2.5-induced endothelial cell apoptosis. Moreover, PM2.5 results in blockage of autophagic flux (failed fusion between autophagosomes and lysosomes), which is detrimental to endothelial cell survival. In conclusion, our findings provide a valuable insight into the relation between autophagy and apoptosis under PM2.5-induced ER stress conditions, where the interplay between them ultimately determines cell fate.

Association between air pollutants and development of chronic kidney disease: A systematic review and meta-analysis

BACKGROUND

The association between incident chronic kidney disease (CKD) or end-stage renal disease (ESRD) and exposure to outdoor air pollution is under debate. We aimed to examine this relationship based on a systematic review with random-effects meta-analysis.

METHODS

We screened the literature on long-term air pollution exposure assessment in the general population using an electronic search of PubMed, Medline, Embase, and Cochrane Library from inception to 20 October 2019. Observational studies investigating the association between long-term exposure to gaseous (CO, SO₂, NO₂, O₃) or particulate (PM_2.5 or PM₁₀) outdoor air pollutants and CKD, ESRD, or renal dysfunction were included, and summary risks were estimated.

RESULTS

Of 4419 identified articles, 23 met our inclusion criteria after screening and 14 were included in the meta-analysis. Pooled effect estimates had the following summary risk ratios (RRs) for CKD: 1.10 (95% confidence intervals [CI] 1.00, 1.21; derived from four studies) per 10 μg/m³ increase in PM_2.5 and 1.16 (95% CI 1.05, 1.29; derived from four studies) for PM₁₀; 1.31 (95% CI 0.86, 2.00; derived from two studies) per 10 ppm increase in CO; and 1.11 (95% CI 1.09, 1.14; derived from three studies) per 10 ppb increase in NO₂. For the pooled effect on eGFR, increases in PM₁₀ and PM_2.5 (of 10 μg/m³) were associated with eGFR decline by -0.83 (95% CI -1.54, -0.12; derived from two studies) and -4.11 (95% CI -12.64, 4.42; derived from two studies) mL/min/1.73 m², respectively.

CONCLUSIONS

Air pollution was observed to be associated with CKD and renal function decline. Although more longitudinal studies are required, we argue that air pollution is pernicious to kidney health.

Autophagy role in environmental pollutants exposure

During the last decades, the potential harmfulness derived from the exposure to environmental pollutants has been largely demonstrated, with associated damages ranging from geno- and cyto-toxicity to tissue malfunction and alterations in organism physiology. Autophagy is an evolutionarily-conserved cellular mechanism essential for cellular homeostasis, which contributes to protect cells from a wide variety of intracellular and extracellular stressors. Due to its pivotal importance, its correct functioning is directly linked to cell, tissue and organismal fitness. Environmental pollutants, particularly industrial compounds, are able to impact autophagic flux, either by increasing it as a protective response, by blocking it, or by switching its protective role toward a pro-cell death mechanism. Thus, the understanding of the effects of chemicals exposure on autophagy has become highly relevant, offering new potential approaches for risk assessment, protection and preventive measures to counteract the detrimental effects of environmental pollutants on human health.

Maternal exposure to fine particle matters cause autophagy via UPR-mediated PI3K-mTOR pathway in testicular tissue of adult male mice in offspring

Epidemiological studies have shown that particulate matters are closely related to human infertility. However, the long-term risk of particulate matters exposure in early life is rarely considered. For the first time this study is designed to explore and elucidate the mechanism of maternal exposure to fine particle matters (PM_2.5) on autophagy in spermatogenic cells of adult offspring. Pregnant C57BL/6 mice were randomly divided into four groups. The 4.8 mg/kg.b.w group and the 43.2 mg/kg.b.w group were administered with different doses of PM_2.5. The membrane control group was administered with PM_2.5 sampling membrane and the control group received no treatment. The exposure was performed every three days from the day after vaginal plug was checked until delivery for a total of 6 times. The results showed that sperms motility and sperms concentration decreased, and sperm deformity increased in adult male offspring. The expression of SOD decreased and MDA increased. Moreover, the level of GRP78/ATF6 and P62 was upregulated, and the expression of PI3K/Akt/mTOR/p-mTOR was down-regulated. This suggests that early-life exposure to PM_2.5 can induce autophagy through the PI3K/Akt/mTOR pathway mediated by unfolded protein response in adult testicular tissue. PM_2.5 may pose a significant role and long-term threat to adult after early-life exposure.

Extract of Cornus officinalis Protects Keratinocytes from Particulate Matter-induced Oxidative Stress

The skin is one of the large organs in the human body and the most exposed to outdoor contaminants such as particulate matter < 2.5 µm (PM_2.5). Recently, we reported that PM_2.5 induced cellular macromolecule disruption of lipids, proteins, and DNA, via reactive oxygen species, eventually causing cellular apoptosis of human keratinocytes. In this study, the ethanol extract of Cornus officinalis fruit (EECF) showed anti-oxidant effect against PM_2.5-induced cellular oxidative stress. EECF protected cells against PM_2.5-induced DNA damage, lipid peroxidation, and protein carbonylation. PM_2.5 up-regulated intracellular and mitochondrial Ca²⁺ levels excessively, which led to mitochondrial depolarization and cellular apoptosis. However, EECF suppressed the PM_2.5-induced excessive Ca²⁺ accumulation and inhibited apoptosis. The data confirmed that EECF greatly protected human HaCaT keratinocytes from PM_2.5-induced oxidative stress.

A Method to Assess and Reduce Pollutant Emissions of Logistic Transportation under Adverse Weather

With the increase of vehicle activities and adverse weather under the background of modernization and global warming, more attention should be paid to vehicle emissions reduction in such circumstances for environmental protection and sustainable transportation. Different from some typical measures, e.g., relevant government policies, improvement of vehicle hardware technologies, and optimization of traffic management, this paper develop a new method based on emergency path optimization to evaluate and reduce pollutant emissions of logistic transportation under adverse weather. Firstly, we establish a calculation model of pollutant emissions (LT-PE model) to calculate the amount of vehicle pollutant emissions produced under adverse weather. Then, a co-evolving path optimization (CEPO) method-based ripple-spreading algorithm is proposed in order to reduce pollutant emissions. To validate the effectiveness of the proposed method, this paper selects fruit logistics transportation affected by typhoon in China’s Hainan Island as a case study. The results show that total vehicle pollutant emissions from the fruit transportation of 35 farms under the typhoon are 28.1% more than when there is no typhoon. The proposed method can reduce pollutant emissions by 21.2% compared with the traditional methods under typhoon.