Changes in extrapulmonary organs and serum enzyme biomarkers after chronic exposure to Buenos Aires air pollution

Exposure to airborne particulate matter and undernutrition in young rats: An in-depth histopathological and biochemical study on lung and excretory organs

Environmental stressors, such as air particulate matter (PM) and nutrient deficiencies, can significantly impact crucial organs involved in detoxifying xenobiotics, including lungs, liver, and kidneys, especially in vulnerable populations like children. This study investigated the effect of 4-week exposure to Residual Oil Fly Ash (ROFA) on these organs in young rats under growth-restricted nutrition (NGR). We assessed histological, histomorphometric and biochemical parameters. ROFA exposure induced histological changes and inflammation in all three organs when compared to control (C) animals. Specifically, in lungs ROFA caused a significant reduction in alveolar airspace (C: 55.8 ± 1.8% vs. ROFA: 38.7 ± 3.0%, p < 0.01) and alveolar number along with changes in alveolar size distribution, and disruption of the smooth muscle layer which may impaired respiratory function. In the liver, ROFA increased binucleated cells, macro and microvesicles and both AST and ALT serum biomarkers (AST: C = 77.7 ± 1.3 vs. ROFA = 81.6 ± 1.3, p < 0.05; ALT: C = 44.5 ± 0.9 vs. ROFA = 49.4 ± 1.3, p < 0.05). In the kidneys, a reduced Bowman's space (C: 2.15 ± 0.2 mm2 vs. ROFA: 1.74 ± 0.2 mm2, p < 0.05) was observed, indicative of glomerular filtration failure. NGR alone reduced Bowman's space (C: 2.15 ± 0.2 mm2 vs. NGR: 1.06 ± 0.1 mm2, p < 0.001). In lung and liver NGR showed higher levels of proinflammatory cytokine IL-6 (p < 0.01 and p < 0.001, respectively) when compared to C. In conclusion, both stressors negatively affected lung and excretory organs in young rats, with nutritional status further modulating the physiological response to ROFA. These findings highlight the compounded risks posed by environmental pollutants and poor nutrition in vulnerable populations.

Decreased immune response in undernourished rats after air pollution exposure

Children are highly vulnerable subpopulation to malnutrition and air pollution. We investigate, in a rat nutritional growth retardation (NGR) model, the impact of Residual Oil Fly Ash (ROFA) on the lung immune response using in vitro and ex vivo methods. In vitro: Alveolar macrophages (AM) were isolated from Control (C) and NGR animals, cultured and treated with ROFA (1-100 µg/ml) for 24 h. Ex vivo: C and NGR rats were intranasally instilled with ROFA (1 mg/kg BW) or PBS. 24 h post-exposure AM were isolated and cultured. ROFA-treatment increased superoxide anion production and TNFα secretion in C-AM in vitro, though for NGR-AM this response was lower. A similar pattern was observed for TNFα and IL-6 secretion in ex vivo experiments. Regarding the antioxidant response, although NGR-AM showed increased Nrf2, after ROFA instillation an attenuated activation was observed. To conclude, chronic undernutrition altered AM response to ROFA affecting immune responsiveness to air pollutants.

Air pollution, alcohol consumption, and the risk of elevated liver enzyme levels: a cross-sectional study in the UK Biobank

Evidences on the association between exposure to air pollution and liver enzymes was scarce in low pollution area. We aimed to investigate the association between air pollution and liver enzyme levels and further explore whether alcohol intake influence this association. This cross-sectional study included 425,773 participants aged 37 to 73 years from the UK Biobank. Land Use Regression was applied to assess levels of PM2.5, PM10, NO2, and NOx. Levels of liver enzymes including AST, ALT, GGT, and ALP were determined by enzymatic rate method. Long-term low-level exposure to PM2.5 (per 5-μg/m3 increase) was significantly associated with AST (0.596% increase, 95% CI, 0.414 to 0.778%), ALT (0.311% increase, 0.031 to 0.593%), and GGT (1.552% increase, 1.172 to 1.933%); The results were similar for PM10; NOX and NO2 were only significantly correlated with AST and GGT Significant modification effects by alcohol consumption were found (P-interaction < 0.05). The effects of pollutants on AST, ALT, and GGT levels gradually increased along with the weekly alcohol drinking frequency. In conclusion, long-term low-level air pollutants exposure was associated with elevated liver enzyme levels. And alcohol intake may exacerbate the effect of air pollution on liver enzymes.

Long-term exposure to ambient air pollution and serum liver enzymes in older adults: a population-based longitudinal study

PURPOSE

To investigate the association of long-term exposure to ambient air pollution with serum liver enzymes in older adults.

METHODS

In this longitudinal study, we investigated 318,911 adults aged ≥65 years and assessed their long-term residential exposure to particulate matter with an aerodynamic diameter ≤2.5 µm (PM_2.5), particulate matter with an aerodynamic diameter ≤10 µm (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃). Linear mixed models and generalized linear mixed models were implemented for exposure-response analyses.

RESULTS

Each interquartile range (IQR) increase of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ exposures was significantly associated with a 4.6%, 4.6%, 5.6%, 4.6%, 6.2%, and 3.6% increase in alanine aminotransferase (ALT), and a 4.6%, 5.2%, 3.6%, 3.3%, 6.1%, and 4.0% increase in aspartate aminotransferase (AST), respectively. Each IQR increase of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ exposures was significantly associated with a 23%, 24%, 28%, 17%, 31%, and 19% increase in odds of elevated ALT (>40 U/L), and a 32%, 39%, 40%, 32%, 57%, and 25% increase in odds of elevated AST (>40 U/L), respectively.

CONCLUSIONS

Long-term exposure to ambient air pollution was significantly associated with increased serum liver enzyme levels in older adults, suggesting that air pollution exposures may induce hepatocellular injury.

Chronic exposure to polluted urban air aggravates myocardial infarction by impaired cardiac mitochondrial function and dynamics

Air pollution exposure positively correlates with increased cardiovascular morbidity and mortality rates, mainly due to myocardial infarction (MI). Herein, we aimed to study the metabolic mechanisms underlying this association, focusing on the evaluation of cardiac mitochondrial function and dynamics, together with its impact over MI progression. An initial time course study was performed in BALB/c mice breathing filtered air (FA) or urban air (UA) in whole-body exposure chambers located in Buenos Aires City downtown for up to 16 weeks (n = 8 per group and time point). After 12 weeks, lung inflammatory cell recruitment was evident in UA-exposed mice. Interestingly, impaired redox metabolism, characterized by decreased lung SOD activity and increased GSSG levels and NOX activity, precede local inflammation in this group. At this selected time point, additional mice were exposed to FA or UA (n = 12 per group) and alveolar macrophage PM uptake and nitric oxide (NO) production was observed in UA-exposed mice, together with increased pro-inflammatory cytokine levels (TNF-α and IL-6) in BAL and plasma. Consequently, impaired heart tissue oxygen metabolism and altered mitochondrial ultrastructure and function were observed in UA-exposed mice after 12 weeks, characterized by decreased active state respiration and ATP production rates, and enhanced mitochondrial H₂O₂ production. Moreover, disturbed cardiac mitochondrial dynamics was detected in this group. This scenario led to a significant increase in the area of infarcted tissue following myocardial ischemia reperfusion injury in vivo, from 43 ± 3% of the area at risk in mice breathing FA to 66 ± 4% in UA-exposed mice (n = 6 per group, p < 0.01), together with a sustained increase in LVEDP during myocardial reperfusion. Taken together, our data unravel cardiac mitochondrial mechanisms that contribute to the understanding of the adverse health effects of urban air pollution exposure, and ultimately highlight the importance of considering environmental factors in the development of cardiovascular diseases.

Urban air pollution induces alterations in redox metabolism and mitochondrial dysfunction in mice brain cortex

Previous reports indicate that the central nervous system (CNS) is a target of air pollution, causing tissue damage and functional alterations. Oxidative stress and neuroinflammation have been pointed out as possible mechanisms mediating these effects. The aim of this work was to study the chronic effects of urban air pollution on mice brain cortex, focusing on oxidative stress markers, and mitochondrial function. Male 8-week-old BALB/c mice were exposed to filtered air (FA, control) or urban air (UA) inside whole-body exposure chambers, located in a highly polluted area of Buenos Aires city, for up to 4 weeks. Glutathione levels, assessed as GSH/GSSG ratio, were decreased after 1 and 2 weeks of exposure to UA (45% and 25% respectively vs. FA; p < 0.05). A 38% increase in lipid peroxidation was found after 1 week of UA exposure (p < 0.05). Regarding protein oxidation, carbonyl content was significantly increased at week 2 in UA-exposed mice, compared to FA-group, and an even higher increment was found after 4 weeks of exposure (week 2: 40% p < 0.05, week 4: 54% p < 0.001). NADPH oxidase (NOX) and glutathione peroxidase (GPx) activities were augmented at all the studied time points, while superoxide dismutase (Cu,Zn-SOD cytosolic isoform) and glutathione reductase (GR) activities were increased only after 4 weeks of UA exposure (p < 0.05). The increased NOX activity was accompanied with higher expression levels of NOX2 regulatory subunit p47^phox, and NOX4 (p < 0.05). Also, UA mice showed impaired mitochondrial function due to a 50% reduction in O₂ consumption in active state respiration (p < 0.05), a 29% decrease in mitochondrial inner membrane potential (p < 0.05), a 65% decrease in ATP production rate (p < 0.01) and a 30% increase in H₂O₂ production (p < 0.01). Moreover, respiratory complexes I-III and II-III activities were decreased in UA group (30% and 36% respectively vs. FA; p < 0.05). UA exposed mice showed alterations in mitochondrial function, increased oxidant production evidenced by NOX activation, macromolecules damage and the onset of the enzymatic antioxidant system. These data indicate that oxidative stress and impaired mitochondrial function may play a key role in CNS damage mechanisms triggered by air pollution.

Review article: Epidemiological and animal evidence for the role of air pollution in intestinal diseases

BACKGROUND

Ambient air pollution is recognized as one of the leading causes of global burden of disease. Involvement of air pollution in respiratory and cardiovascular diseases was first recognized, and then cumulative data has indicated that the intestinal tract could be also damaged.

AIM

To review and discuss the current epidemiological and animal data on the effects of air pollution on intestinal homeostasis.

METHODS

An extensive literature search was conducted using Google Scholar and Pubmed to gather relevant human and animal studies that have reported the effects of any air pollutant on the intestine.

RESULTS

Exposure to several gaseous and particulate matter components of air pollution have been associated either positively or negatively with the onset of various intestinal diseases including appendicitis, gastroenteric disorders, irritable bowel syndrome, inflammatory bowel diseases, and peptic ulcers. Several atmospheric pollutants have been associated with modifications of gut microbiota in humans. Animal studies have showed that inhalation of atmospheric particulate matter can lead to modifications of gut microbiota, impairments of oxidative and inflammatory intestinal balances, and disruption of gut epithelial permeability.

CONCLUSIONS

Overall, the literature appears to indicate that the gut is an underestimated target of adverse health effects induced by air pollution. It is therefore important to develop additional studies that aim to better understand the link between air pollutants and gastro-intestinal diseases.

Polluted Air Exposure Compromises Corneal Immunity and Exacerbates Inflammation in Acute Herpes Simplex Keratitis

Air pollution is a serious environmental issue worldwide in developing countries’ megacities, affecting the population’s health, including the ocular surface, by predisposing or exacerbating other ocular diseases. Herpes simplex keratitis (HSK) is caused by the herpes simplex virus type 1 (HSV-1). The primary or recurring infection in the ocular site causes progressive corneal scarring that may result in visual impairment. The present study was designed to study the immunopathological changes of acute HSK under urban polluted air, using the acute HSK model combined with an experimental urban polluted air exposure from Buenos Aires City. We evaluated the corneal clinical outcomes, viral DNA and pro-inflammatory cytokines by RT-PCR and ELISA assays, respectively. Then, we determined the innate and adaptive immune responses in both cornea and local lymph nodes after HSV-1 corneal by immunofluorescence staining and flow cytometry. Our results showed that mice exposed to polluted air develop a severe form of HSK with increased corneal opacity, neovascularization, HSV-1 DNA and production of TNF-α, IL-1β, IFN-γ, and CCL2. A high number of corneal resident immune cells, including activated dendritic cells, was observed in mice exposed to polluted air; with a further significant influx of bone marrow-derived cells including GR1+ cells (neutrophils and inflammatory monocytes), CD11c+ cells (dendritic cells), and CD3+ (T cells) during acute corneal HSK. Moreover, mice exposed to polluted air showed a predominant Th1 type T cell response over Tregs in local lymph nodes during acute HSK with decreased corneal Tregs. These findings provide strong evidence that urban polluted air might trigger a local imbalance of innate and adaptive immune responses that exacerbate HSK severity. Taking this study into account, urban air pollution should be considered a key factor in developing ocular inflammatory diseases.