Lung permeability, antioxidant status, and NO2 inhalation: a selenium supplementation study in rats

Long-term exposure to traffic-related air pollution and stroke: A systematic review and meta-analysis

BACKGROUND

Stroke remains the second cause of death worldwide. The mechanisms underlying the adverse association of exposure to traffic-related air pollution (TRAP) with overall cardiovascular disease may also apply to stroke. Our objective was to systematically evaluate the epidemiological evidence regarding the associations of long-term exposure to TRAP with stroke.

METHODS

PubMed and LUDOK electronic databases were searched systematically for observational epidemiological studies from 1980 through 2019 on long-term exposure to TRAP and stroke with an update in January 2022. TRAP was defined according to a comprehensive protocol based on pollutant and exposure assessment methods or proximity metrics. Study selection, data extraction, risk of bias (RoB) and confidence assessments were conducted according to standardized protocols. We performed meta-analyses using random effects models; sensitivity analyses were assessed by geographic area, RoB, fatality, traffic specificity and new studies.

RESULTS

Nineteen studies were included. The meta-analytic relative risks (and 95% confidence intervals) were: 1.03 (0.98-1.09) per 1 μg/m³ EC, 1.09 (0.96-1.23) per 10 μg/m³ PM₁₀, 1.08 (0.89-1.32) per 5 μg/m³ PM_2.5, 0.98 (0.92; 1.05) per 10 μg/m³ NO₂ and 0.99 (0.94; 1.04) per 20 μg/m³ NO_x with little to moderate heterogeneity based on 6, 5, 4, 7 and 8 studies, respectively. The confidence assessments regarding the quality of the body of evidence and separately regarding the presence of an association of TRAP with stroke considering all available evidence were rated low and moderate, respectively.

CONCLUSION

The available literature provides low to moderate evidence for an association of TRAP with stroke.

Sex-specific perinatal expression of glutathione peroxidases during mouse lung development

Reports indicate that antioxidant enzymes like the glutathione peroxidases (GPx) can be regulated by sex steroids. The GPx, a major class of antioxidants involved in H(2)O(2) and lipid hydroperoxides neutralization, showed an age- and sex-specific expression in many adult organs including the lung. High levels of androgens in the male lung are known to delay the surge of surfactant synthesis during gestation in several species. However, the impact of male androgens on antioxidant GPx early in life remains to be determined. The objective was to study the lung sex-specific expression of GPx during BALB/c mouse perinatal development. The mRNA expression of four seleno-dependent Gpx (Gpx1 to 4) in the lung of both sexes was characterized by real-time PCR from gestational day 15 to postnatal day 30, covering the entire canalicular, saccular and alveolar stages. Immunohistochemistry of GPx-1, -3 and -4, and seleno-dependent GPx enzymatic assays were also performed in the lung. We found a transient lower Gpx1 mRNA level in male than in female lungs during the first 5 days after birth, corresponding to the saccular phase. This dimorphic expression was concomitant to a sex difference in GPx enzymatic activity corrected for blood. It is, to our knowledge, the first report of a sex dimorphism for murine lung enzymatic antioxidant defenses during the perinatal period.

Oxidative stress, endothelial dysfunction and inflammatory response in rat heart to NO₂ inhalation exposure

Epidemiological studies suggest that NO₂ inhalation is associated with adverse effects on heart-related health, however, existing experimental data lack relevant evidences. In this study, a role for oxidative stress, endothelial dysfunction and inflammatory responses in the heart of rats treated with different concentrations of NO₂ (0, 5, 10 and 20 mg m⁻³) was investigated. Mild heart pathology occurred after 7-d exposure (6 h d⁻¹). Marked oxidative stress were induced as evaluated by reduction/induction of antioxidants (Cu/Zn-SOD, Mn-SOD and GPx) activity and increasing formation of MDA and PCO. Also, mRNA and protein biomarkers of vasoconstriction (ET-1, eNOS) and inflammation (TNF-α, IL-1β and ICAM-1) were up-regulated, and p53 mRNA expression, bax/bcl-2 ratio and the mean number of TUNEL-positive myocytes were increased as well. All the results implicate that NO₂ exerted injuries to mammals' heart, and the damage mechanisms were possibly associated with oxidative stress, endothelial dysfunction and inflammation.

Acute effects of diesel emission from the urea selective catalytic reduction engine system on male rats

Short-term inhalation experiments were performed using Fischer 344 rats exposed to emission from the urea selective catalytic reduction (SCR) diesel engine system to identify health effects and compare them to those of the conventional diesel engine system. Rats were exposed to high-, middle-, or low-concentration emission (dilution ratio 1:29, 1:290, or 1:580) or clean air (control) for 1, 3, or 7 days (6 h/day), under driving conditions at a speed of 1320 rpm and a torque of 840 Nm. For the high-concentration group, the major components of the urea SCR emission were 0.04 mg/m(3) particulate matter (PM) and 0.78 ppm nitrogen dioxide (NO(2)); those of the conventional emission were 0.95 mg/m(3) PM and 0.31 ppm NO(2). The authors evaluated the respiratory effects of each emission on rats. Lymphocytes for 3-day exposure of both emissions significantly increased in bronchoalveolar lavage fluid, but there were slight differences. With an increase in potential antioxidant (PAO), 8-hydroxy-2'-deoxyguanosine for the urea SCR emission was significantly decreased, but that of the conventional emission was highest among all groups and did not show a response to PAO. In lungs, heme oxygenase (HO)-1 and tumor necrosis factor (TNF)-alpha mRNA expressions for the urea SCR emission showed a tendency to increase compared to those of the conventional emission. Thus, gene analysis results suggested that NO(2) from the urea SCR emission affected the expressions of mRNAs in lungs. However, as a whole, the results suggested that the health effects of the urea SCR emission might be less than the conventional emission on rats.

Relationship between selenium accumulation and mycelial cell composition in Lentinula edodes (Berk.) cultures

It was postulated that fractions enriched in selenium (Se) isolated from Lentinula edodes mycelium polysaccharide might possess higher biological activity than the non-enriched fractions currently used to treat cancer. In order to obtain Se-enriched mycelial preparations, L. edodes cultures were cultivated in media enriched with sodium selenite. In order to determine whether the concentration of Se in the culture medium affected the biosynthesis and composition of cell wall and cell membrane, concentrations of the exopolysaccharide (EPS), chitin, and sterol (ergosterol) were measured in harvested mycelia. In addition, the relationship between Se accumulation and content of polyphenols and vitamin D(2) in L. edodes mycelium was examined. The effects of Se levels on the mycelium cell composition were determined in culture media enriched with Se at concentrations ranging from 0 to 30 microg/ml. In each culture mycelial growth, total Se and Se distribution were determined between mycelial fractions of different polarity. The EPS, polyphenolics, and ergosterol content in harvested mycelia rose in proportion to Se concentration in the culture medium. The chitin content in mycelia increased with Se concentrations in the range 0-5 microg/ml, but at higher concentrations chitin levels decreased. Data showed that Se in culture medium exerted potent effects on the composition of the mushroom cell wall and semipermeable membrane, and on the content of polyphenolics that are involved in detoxification processes. Our findings indicate the optimal concentration of Se required in the culture medium for maximal yield of immunostimulatory-active selenated exopolysaccharides.

Oxidants and the pathogenesis of lung diseases

The increasing number of population-based and epidemiologic associations between oxidant pollutant exposures and cardiopulmonary disease exacerbation, decrements in pulmonary function, and mortality underscores the important detrimental effects of oxidants on public health. Because inhaled oxidants initiate a number of pathologic processes, including inflammation of the airways, which may contribute to the pathogenesis and/or exacerbation of airways disease, it is critical to understand the mechanisms through which exogenous and endogenous oxidants interact with molecules in the cells, tissues, and epithelial lining fluid of the lung. Furthermore, it is clear that interindividual variation in response to a given exposure also exists across an individual lifetime. Because of the potential impact that oxidant exposures may have on reproductive outcomes and infant, child, and adult health, identification of the intrinsic and extrinsic factors that may influence susceptibility to oxidants remains an important issue. In this review, we discuss mechanisms of oxidant stress in the lung, the role of oxidants in lung disease pathogenesis and exacerbation (eg, asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome), and the potential risk factors (eg, age, genetics) for enhanced susceptibility to oxidant-induced disease.