Fish oil blunts lung function decrements induced by acute exposure to ozone in young healthy adults: A randomized trial

Fatty acids metabolism in ozone-induced pulmonary inflammatory injury: Evidence, mechanism and prevention

Ozone (O3) is a major air pollutant that directly threatens the respiratory system, lung fatty acid metabolism disorder is an important molecular event in pulmonary inflammatory diseases. Liver kinase B1 (LKB1) and nucleotide-binding domain leucine-rich repeat-containing protein 3 (NLRP3) inflammasome not only regulate inflammation, but also have close relationship with fatty acid metabolism. However, the role and mechanism of LKB1 and NLRP3 inflammasome in lung fatty acid metabolism, which may contribute to ozone-induced lung inflammation, remain unclear, and effective strategy for preventing O3-induced pulmonary inflammatory injury is lacking. To explore these, mice were exposed to 1.00 ppm O3 (3 h/d, 5 days), and pulmonary inflammation was determined by airway hyperresponsiveness, histopathological examination, total cells and cytokines in bronchoalveolar lavage fluid (BALF). Targeted fatty acids metabolomics was used to detect medium and long fatty acid in lung tissue. Then, using LKB1-overexpressing adenovirus and NLRP3 knockout (NLRP3-/-) mice to explore the mechanism of O3-induced lung fatty acid metabolism disorder. Results demonstrated that O3 exposure caused pulmonary inflammatory injury and lung medium and long chain fatty acids metabolism disorder, especially decreased dihomo-γ-linolenic acid (DGLA). Meanwhile, LKB1 expression was decreased, and NLRP3 inflammasome was activated in lung of mice after O3 exposure. Additionally, LKB1 overexpression alleviated O3-induced lung inflammation and inhibited the activation of NLRP3 inflammasome. And we found that pulmonary fatty acid metabolism disorder was ameliorated of NLRP3 -/- mice compared with those in wide type mice after O3 exposure. Furthermore, administrating DGLA intratracheally prior to O3 exposure significantly attenuated O3-induced pulmonary inflammatory injury. Taken together, these findings suggest that fatty acids metabolism disorder is involved in O3-induced pulmonary inflammation, which is regulated by LKB1-mediated NLRP3 pathway, DGLA supplement could be a useful preventive strategy to ameliorate ozone-associated lung inflammatory injury.

Dietary supplementations to mitigate the cardiopulmonary effects of air pollution toxicity: A systematic review of clinical trials

BACKGROUND

There is a consistent association between exposure to air pollution and elevated rates of cardiopulmonary illnesses. As public health activities emphasize the paramount need to reduce exposure, it is crucial to examine strategies like the antioxidant diet that could potentially protect individuals who are unavoidably exposed.

METHODS

A systematic search was performed in PubMed/Medline, EMBASE, CENTRAL, and ClinicalTrials.gov up to March 31, 2023, for clinical trials assessing dietary supplements against cardiovascular (blood pressure, heart rate, heart rate variability, brachial artery diameter, flow-mediated dilation, and lipid profile) or pulmonary outcomes (pulmonary function and airway inflammation) attributed to air pollution exposure.

RESULTS

After reviewing 4681 records, 18 studies were included. There were contradictory findings on the effects of fish oil and olive oil supplementations on cardiovascular outcomes. Although with limited evidence, fish oil offered protection against pulmonary dysfunction induced by pollutants. Most studies on vitamin C did not find protective cardiovascular effects; however, the combination of vitamin C and E offered protective effects against pulmonary dysfunction but showed conflicting results for cardiovascular outcomes. Other supplements like sulforaphane, L-arginine, n-acetylcysteine, and B vitamins showed potential beneficial effects but need further research due to the limited number of existing trials.

CONCLUSIONS

Although more research is needed to determine the efficacy and optimal dose of anti-inflammatory and antioxidant dietary supplements against air pollution toxicity, this low-cost preventative strategy has the potential to offer protection against outcomes of air pollution exposure.

Could the association between ozone and arterial stiffness be modified by fish oil supplementation?

BACKGROUND

Arterial stiffness (AS) is an important predicting factor for cardiovascular disease. However, no epidemiological studies have ever explored the mediating role of biomarkers in the association between ozone and AS, nor weather fish oil modified such association.

METHODS

Study participants were drawn from the UK biobank, and a total of 95,699 middle-aged and older adults were included in this study. Ozone was obtained from Community Multiscale Air Quality (CMAQ) model matched to residential addresses, fish oil from self-reported intake, and arterial stiffness was based on device measurements. First, we applied a double robust approach to explore the association between ozone or fish oil intake and arterial stiffness, adjusting for potential confounders at the individual and regional levels. Then, how triglycerides, apolipoprotein B (Apo B)/apolipoprotein A (ApoA) and non-high-density lipoprotein cholesterol (Non-HDL-C) mediate the relationship between ozone and AS. Last, the modifying role of fish oil was further explored by stratified analysis.

RESULTS

The mean age of participants was 55 years; annual average ozone exposure was associated with ASI (beta:0.189 [95%CI: 0.146 to 0.233], P < 0.001), and compared to participants who did not consume fish oil, fish oil users had a lower ASI (beta: 0.061 [95%CI: -0.111 to -0.010], P = 0.016). The relationship between ozone exposure and AS was mediated by triglycerides, ApoB/ApoA, and Non-HDL-C with mediation proportions ranging from 10.90% to 18.30%. Stratified analysis showed lower estimates on the ozone-AS relationship in fish oil users (P = 0.011).

CONCLUSION

Ozone exposure was associated with higher levels of arterial stiffness, in contrast to fish oil consumption, which showed a protective association. The association between ozone exposure and arterial stiffness was partially mediated by some biomarkers. In the general population, fish oil consumption might provide protection against ozone-related AS.

Docosahexaenoic Acid Controls Pulmonary Macrophage Lipid Raft Size and Inflammation

BACKGROUND

Docosahexaenoic acid (DHA) controls the biophysical organization of plasma membrane sphingolipid/cholesterol-enriched lipid rafts to exert anti-inflammatory effects, particularly in lymphocytes. However, the impact of DHA on the spatial arrangement of alveolar macrophage lipid rafts and inflammation is unknown.

OBJECTIVES

The primary objective was to determine how DHA controls lipid raft organization and function of alveolar macrophages. As proof-of-concept, we also investigated DHA's anti-inflammatory effects on select pulmonary inflammatory markers with a murine influenza model.

METHODS

MH-S cells, an alveolar macrophage line, were treated with 50 μM DHA or vehicle control and were used to study plasma membrane molecular organization with fluorescence-based methods. Biomimetic membranes and coarse grain molecular dynamic (MD) simulations were employed to investigate how DHA mechanistically controls lipid raft size. qRT-PCR, mass spectrometry, and ELISAs were used to quantify downstream inflammatory signaling transcripts, oxylipins, and cytokines, respectively. Lungs from DHA-fed influenza-infected mice were analyzed for specific inflammatory markers.

RESULTS

DHA increased the size of lipid rafts while decreasing the molecular packing of the MH-S plasma membrane. Adding a DHA-containing phospholipid to a biomimetic lipid raft-containing membrane led to condensing, which was reversed with the removal of cholesterol. MD simulations revealed DHA nucleated lipid rafts by driving cholesterol and sphingomyelin into rafts. Downstream of the plasma membrane, DHA lowered the concentration of select inflammatory transcripts, oxylipins, and IL-6 secretion. DHA lowered pulmonary Il6 and Tnf-α mRNA expression and increased anti-inflammatory oxylipins of influenza-infected mice.

CONCLUSIONS

The data suggest a model in which the localization of DHA acyl chains to nonrafts is driving sphingomyelin and cholesterol molecules into larger lipid rafts, which may serve as a trigger to impede signaling and lower inflammation. These findings also identify alveolar macrophages as a target of DHA and underscore the anti-inflammatory properties of DHA for lung inflammation.

Long-term ambient ozone, omega-3 fatty acid, genetic susceptibility, and risk of mental disorders among middle-aged and older adults in UK biobank

BACKGROUND

Evidence linking ozone to depression and anxiety disorders remains sparse and results are heterogeneous. It remains unknown whether omega-3 fatty acid, or genetic susceptibility of mental disorders modify the impacts of ozone. The aim is to assess the associations of ambient ozone with depression and anxiety, and further explore the potential modification effects of omega-3 fatty acid and genetic susceptibility.

METHODS

In total of 257,534 participants were enrolled from 2006 to 2010 and followed up to 2016. Depression and anxiety were assessed using mental health questionnaires, primary care records and hospital admission records. The annual average concentrations of ozone were calculated and linked to individuals by home address. Dietary intake and plasma concentration were selected to reflect levels of omega-3 fatty acid. Polygenetic risk scores were selected to reflect genetic susceptibility. We examined the associations of ozone and incident mental disorders, and potential modification of omega-3 fatty acid and genetic susceptibility.

RESULTS

Incidences of depression (N = 6957) and anxiety (N = 6944) was associated with increase of ozone. Higher levels of omega-3 fatty acid might attenuate the ozone related depression risk. However, the modification effects of genetic susceptibility were not found.

CONCLUSIONS

Long-term exposure to ambient ozone increase the risk of mental disorders among the middle aged and older adults, and omega-3 fatty acid could reduce the adverse effects of ozone on mental health. Higher intake of omega-3 fatty acid is a potential strategy to prevent the risks caused by ozone on public mental health.

Respiratory Health Effects of Air Pollutants

Air pollution is a risk factor for asthma and respiratory infection. Avoidance of air pollution is the best approach to mitigating the impacts of pollution. Personal preventive strategies are possible, but policy interventions are the most effective ways to prevent pollution and its effect on asthma and respiratory infection.

Air Pollution and Diet: Potential Interacting Exposures in Asthma

PURPOSE OF REVIEW

To provide a review of emerging literature describing the impact of diet on the respiratory response to air pollution in asthma.

RECENT FINDINGS

Asthma phenotyping (observable characteristics) and endotyping (mechanistic pathways) have increased the specificity of diagnostic and treatment pathways and opened the doors to the identification of subphenotypes with enhanced susceptibility to exposures and interventions. Mechanisms underlying the airway immune response to air pollution are still being defined but include oxidative stress, inflammation, and activation of adaptive and innate immune responses, with genetic susceptibility highlighted. Of these, neutrophil recruitment and activation appear prominent; however, understanding neutrophil function in response to pollutant exposures is a research gap. Diet may play a role in asthma pathogenesis and morbidity; therefore, diet modification is a potential target opportunity to protect against pollutant-induced lung injury. In particular, in vivo and in vitro data suggest the potential for diet to modify the inflammatory response in the airways, including impacts on neutrophil recruitment and function. Murine models provide compelling results in regard to the potential for dietary components (including fiber, antioxidants, and omega-3 fatty acids) to buffer against the inflammatory response to air pollution in the lung. Precision lifestyle approaches to asthma management and respiratory protection in the context of air pollution exposures may evolve to include diet, pending the results of further epidemiologic and causal investigation and with neutrophil recruitment and activation as a candidate mechanism.

A Narrative Review on the Impact of Air Pollution on Heart Failure Risk and Exacerbation

Air pollution is a risk factor for many cardiovascular diseases, including heart failure (HF). Although the links between air pollution and HF have been explored, the results are scattered and difficult to piece together into a cohesive story. Therefore, we undertook a narrative review of all aspects of the relationship between HF and air pollution exposure, including risks of developing HF when exposed to air pollution, the exacerbation of HF symptoms by air pollution exposure, and the increased susceptibility that individuals with HF have for air pollution-related health risks. We also examined the literature on environmental justice as well as air pollution interventions for HF. We found substantial evidence linking air pollution exposure to HF incidence. There were a limited number of studies that examined air pollution exposure in clearly defined populations with HF to explore exacerbation of HF or the susceptibility of individuals with HF to air pollution health risks. However, there is substantial evidence that HF-related hospitalisations are increased under air pollution exposure and that the air pollution associated increase in HF-related hospitalisations is greater than hospitalisations for other chronic diseases, supporting links between air pollution and both exacerbation of HF and susceptibility of individuals with HF. There is emerging evidence for interventions that can decrease air pollution health risks for individuals with HF, and more studies are needed, particularly randomised controlled trials. Thus, although the air pollution-related health risks for HF incidence and hospitalisations are clear, further studies specifically targeted at identified data gaps will greatly improve our knowledge of the susceptibility of individuals with HF and interventions to reduce risks.

Effects of Controlled Ozone Exposure on Circulating microRNAs and Vascular and Coagulation Biomarkers: A Mediation Analysis

Exposure to ozone (O3) is associated with adverse respiratory and cardiovascular outcomes. Alterations in circulating microRNAs (miRNAs) may contribute to the adverse vascular effects of O3 exposure through inter-cellular communication resulting in post-transcriptional regulation of messenger RNAs by miRNAs. In this study, we investigated whether O3 exposure induces alterations in circulating miRNAs that can mediate effects on downstream vascular and coagulation biomarkers. Twenty-three healthy male adults were exposed on successive days to filtered air and 300 ppb O3 for 2 h. Circulating miRNA and protein biomarkers were quantified after each exposure session. The data were subjected to mixed-effects model and mediation analyses for the statistical analyses. The results showed that the expression level of multiple circulating miRNAs (e.g., miR-19a-3p, miR-34a-5p) was significantly associated with O3 exposure. Pathway analysis showed that these miRNAs were predictive of changing levels of downstream biomarkers [e.g., D-dimer, C-reactive protein, tumor necrosis factor α (TNFα)]. Mediation analysis showed that miR-19a-3p may be a significant mediator of O3-exposure-induced changes in blood TNFα levels [0.08 (0.01, 0.15), p = 0.02]. In conclusion, this preliminary study showed that O3 exposure of healthy male adults resulted in changes in circulating miRNAs, some of which may mediate vascular effects of O3 exposure.