The effects of exercise training on the lungs and cardiovascular function of animals exposed to diesel exhaust particles and gases

Demystifying roles of exercise in immune response regulation against acute respiratory infections: A narrative review

The benefits of physical activity and exercise, especially those classified as moderate-to-vigorous activity (MVPA), have been well-established in preventing non-communicable diseases and mental health problems in healthy adults. However, the relationship between physical activity and exercise and the prevention and management of acute respiratory infection (ARI), a global high-burden disease, has been inconclusive. There have been debates and disagreements among scientific publications regarding the relationship between exercise and immune response against the causative agents of ARI. This narrative review aims to explore the theory that sufficiently explains the correlation between exercise, immune response, and ARI. The potential root causes of discrepancies come from research associated with the "open window" hypothesis. The studies have several limitations, and future improvements to address them are urgently needed in the study design, data collection, exercise intervention, subject recruitment, biomarkers for infection and inflammation, nutritional and metabolism status, and in addressing confounding variables. In conclusion, data support the clinical advantages of exercise have a regulatory contribution toward improving the immune response, which in turn potentially protects humans fromARI. However, the hypothesis related to its negative effect must be adopted cautiously.

Emerging concern on air pollution and health: Trade-off between air pollution exposure and physical activity

Air pollution is a major contributor to the global disease burden, especially affecting respiratory and cardiovascular health. However, physical activity is associated with improved lung function, a slower decline in lung function, and lower mortality. The public is more likely to be exposed to air pollution during outdoor physical activity. However, studies on how long-term and short-term exposure to air pollution interacts with physical activity yield inconsistent results, and the thresholds for air pollution and physical activity remain unclear. Thus, more studies are needed to provide sufficient evidence to guide the public to safely engage in outdoor physical activity when exposed to air pollution.

Long-term PM1 exposure and hypertension hospitalization: A causal inference study on a large community-based cohort in South China

Limited evidence exists on the effect of submicronic particulate matter (PM1) on hypertension hospitalization. Evidence based on causal inference and large cohorts is even more scarce. In 2015, 36,271 participants were enrolled in South China and followed up through 2020. Each participant was assigned single-year, lag0-1, and lag0-2 moving average concentration of PM1 and fine inhalable particulate matter (PM2.5) simulated based on satellite data at a 1-km resolution. We used an inverse probability weighting approach to balance confounders and utilized a marginal structural Cox model to evaluate the underlying causal links between PM1 exposure and hypertension hospitalization, with PM2.5-hypertension association for comparison. Several sensitivity studies and the analyses of effect modification were also conducted. We found that a higher hospitalization risk from both overall (HR: 1.13, 95% CI: 1.05-1.22) and essential hypertension (HR: 1.15, 95% CI: 1.06-1.25) was linked to each 1 µg/m3 increase in the yearly average PM1 concentration. At lag0-1 and lag0-2, we observed a 17%-21% higher risk of hypertension associated with PM1. The effect of PM1 was 6%-11% higher compared with PM2.5. Linear concentration-exposure associations between PM1 exposure and hypertension were identified, without safety thresholds. Women and participants that engaged in physical exercise exhibited higher susceptibility, with 4%-22% greater risk than their counterparts. This large cohort study identified a detrimental relationship between chronic PM1 exposure and hypertension hospitalization, which was more pronounced compared with PM2.5 and among certain groups.

Aerobic physical training reduces severe asthma phenotype involving kinins pathway

INTRODUCTION

Aerobic physical training (APT) reduces eosinophilic airway inflammation, but its effects and mechanisms in severe asthma remain unknown.

METHODS

An in vitro study employing key cells involved in the pathogenesis of severe asthma, such as freshly isolated human eosinophils, neutrophils, and bronchial epithelial cell lineage (BEAS-2B) and lung fibroblasts (MRC-5 cells), was conducted. Additionally, an in vivo study using male C57Bl/6 mice, including Control (Co; n = 10), Trained (Exe; n = 10), house dust mite (HDM; n = 10), and HDM + Trained (HDM + Exe; n = 10) groups, was carried out, with APT performed at moderate intensity, 5x/week, for 4 weeks.

RESULTS

HDM and bradykinin, either alone or in combination, induced hyperactivation in human neutrophils, eosinophils, BEAS-2B, and MRC-5 cells. In contrast, IL-10, the primary anti-inflammatory molecule released during APT, inhibited these inflammatory effects, as evidenced by the suppression of numerous cytokines and reduced mRNA expression of the B1 receptor and ACE-2. The in vivo study demonstrated that APT decreased bronchoalveolar lavage levels of bradykinin, IL-1β, IL-4, IL-5, IL-17, IL-33, TNF-α, and IL-13, while increasing levels of IL-10, klotho, and IL-1RA. APT reduced the accumulation of polymorphonuclear cells, lymphocytes, and macrophages in the peribronchial space, as well as collagen fiber accumulation, epithelial thickness, and mucus accumulation. Furthermore, APT lowered the expression of the B1 receptor and ACE-2 in lung tissue and reduced bradykinin levels in the lung tissue homogenate compared to the HDM group. It also improved airway resistance, tissue resistance, and tissue damping. On a systemic level, APT reduced total leukocytes, eosinophils, neutrophils, basophils, lymphocytes, and monocytes in the blood, as well as plasma levels of IL-1β, IL-4, IL-5, IL-17, TNF-α, and IL-33, while elevating the levels of IL-10 and IL-1RA.

CONCLUSION

These findings indicate that APT inhibits the severe asthma phenotype by targeting kinin signaling.

Exercise training inhibits macrophage-derived IL-17A-CXCL5-CXCR2 inflammatory axis to attenuate pulmonary fibrosis in mice exposed to silica

Exposure to crystalline silica leads to health effects beyond occupational silicosis. Exercise training's potential benefits on pulmonary diseases yield inconsistent outcomes. In this study, we utilized experimental silicotic mice subjected to exercise training and pharmacological interventions, including interleukin-17A (IL-17A) neutralizing antibody or clodronate liposome for macrophage depletion. Findings reveal exercise training's ability to mitigate silicosis progression in mice by suppressing scavenger receptor B (SRB)/NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and Toll-like receptor 4 (TLR4) pathways. Macrophage-derived IL-17A emerges as primary source and trigger for silica-induced pulmonary inflammation and fibrosis. Exercise training effectively inhibits IL-17A-CXC motif chemokine ligand 5 (CXCL5)-Chemokine (C-X-C motif) Receptor 2 (CXCR2) axis in silicotic mice. Our study evidences exercise training's potential to reduce collagen deposition, preserve elastic fibers, slow pulmonary fibrosis advancement, and enhance pulmonary function post silica exposure by impeding macrophage-derived IL-17A-CXCL5-CXCR2 axis.

Long-term exposure to air pollution and lung function among children in China: Association and effect modification

Background

Children are vulnerable to the respiratory effects of air pollution, and their lung function has been associated with long-term exposure to low air pollution level in developed countries. However, the impact of contemporary air pollution level in developing countries as a result of recent efforts to improve air quality on children's lung function is less understood.

Methods

We obtained a cross-sectional sample of 617 schoolchildren living in three differently polluted areas in Anhui province, China. 2-year average concentrations of air pollutants at the year of spirometry and the previous year (2017-2018) obtained from district-level air monitoring stations were used to characterize long-term exposure. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), and forced expiratory flow between 25 and 75% of FVC (FEF_25-75) were determined under strict quality control. Multivariable regression was employed to evaluate the associations between air pollution level and lung function parameters, overall and by demographic characteristics, lifestyle, and vitamin D that was determined by liquid chromatography tandem mass spectrometry.

Results

Mean concentration of fine particulate matter was 44.7 μg/m³, which is slightly above the interim target 1 standard of the World Health Organization. After adjusting for confounders, FVC, FEV₁, and FEF_25-75 showed inverse trends with increasing air pollution levels, with children in high exposure group exhibiting 87.9 [95% confidence interval (CI): 9.5, 166.4] mL decrement in FEV₁ and 195.3 (95% CI: 30.5, 360.1) mL/s decrement in FEF_25-75 compared with those in low exposure group. Additionally, the above negative associations were more pronounced among those who were younger, girls, not exposed to secondhand smoke, non-overweight, physically inactive, or vitamin D deficient.

Conclusions

Our study suggests that long-term exposure to relatively high air pollution was associated with impaired lung function in children. More stringent pollution control measures and intervention strategies accounting for effect modification are needed for vulnerable populations in China and other developing countries.

Association between short-term exposure to ambient PM1 and PM2.5 and forced vital capacity in Chinese children and adolescents

This study aims to examine the association between short-term exposure to ambient PM₁, PM_1-2.5, and PM_2.5 and forced vital capacity (FVC). Population data were obtained from a school-based cross-sectional survey in Shandong in 2014. Distributed lag non-linear models were used to examine the association between exposure to PM₁, PM_1-2.5, and PM_2.5 and FVC at the day of FVC measurement and the previous 6 days (lag 0 to 6 days). A total of 35,334 students aged 9 to 18 years were included in the study, and the mean exposure concentrations of ambient PM₁, PM_1-2.5, and PM_2.5 for them were 47.4 (standard deviation [SD] = 21.3) μg/m³, 32.8 (SD = 32.2) μg/m³, and 80.1 (SD = 47.7) μg/m³, respectively. An inter-quartile range (IQR, 24 μg/m³) increment in exposure to PM₁ was significantly associated with a lower FVC at lag 0 and lag 1 day (β =  - 80 mL, 95% CI =  - 119, - 42, and β =  - 37 mL, 95% CI =  - 59, - 16, respectively), and an IQR (54 μg/m³) increment in exposure to PM_2.5 was significantly associated with a lower FVC at lag 0 and lag 1 day (β =  - 57 mL, 95% CI =  - 89, - 18, and β =  - 34 mL, 95% CI =  - 56, - 12, respectively) after adjustment for gender, age, body mass index category, residence, month of the survey, intake of eggs, intake of milk, physical activity, and screen time. No significant associations were observed for PM_1-2.5. The inverse associations of PM₁ and PM_2.5 with FVC were larger in males, younger children, those overweight or obese, and those with insufficient physical activity levels. Short-term exposure to ambient PM₁ and PM_2.5 was associated with decreased FVC, and PM₁ may be the primary fraction of PM_2.5 causing the adverse pulmonary effects. Our findings emphasize the need to address ambient PM, especially PM₁, pollution for affecting pulmonary health in children and adolescents.

Physical Exercise in the Context of Air Pollution: An Emerging Research Topic

Physical exercise (PE) brings physiological benefits to human health; paradoxically, exposure to air pollution (AP) is harmful. Hence, the combined effects of AP and PE are interesting issues worth exploring. The objective of this study is to review literature involved in AP-PE fields to perform a knowledge-map analysis and explore the collaborations, current hotspots, physiological applications, and future perspectives. Herein, cluster, co-citation, and co-occurrence analysis were applied using CiteSpace and VOSviewer software. The results demonstrated that AP-PE domains have been springing up and in rapid growth since the 21st century. Subsequently, active countries and institutions were identified, and the productive institutions were mainly located in USA, China, UK, Spain, and Canada. Developed countries seemed to be the major promoters. Additionally, subject analysis found that environmental science, public health, and sports medicine were the core subjects, and multidimensional communications were forming. Thereafter, a holistic presentation of reference co-citation clusters was conducted to discover the research topics and trace the development focuses. Youth, elite athletes, and rural population were regarded as the noteworthy subjects. Commuter exposure and moderate aerobic exercise represented the common research context and exercise strategy, respectively. Simultaneously, the research hotspots and application fields were elaborated by keyword co-occurrence distribution. It was noted that physiological adaptations including respiratory, cardiovascular, metabolic, and mental health were the major themes; oxidative stress and inflammatory response were the mostly referred mechanisms. Finally, several challenges were proposed, which are beneficial to promote the development of the research field. Molecular mechanisms and specific pathways are still unknown and the equilibrium points and dose-effect relationships remain to be further explored. We are highly confident that this study provides a unique perspective to systematically and comprehensively review the pieces of AP-PE research and its related physiological mechanisms for future investigations.

Physical Activity in Polluted Air-Net Benefit or Harm to Cardiovascular Health? A Comprehensive Review

Both exposure to higher levels of polluted air and physical inactivity are crucial risk factors for the development and progression of major noncommunicable diseases and, in particular, of cardiovascular disease. In this context, the World Health Organization estimated 4.2 and 3.2 million global deaths per year in response to ambient air pollution and insufficient physical activity, respectively. While regular physical activity is well known to improve general health, it may also increase the uptake and deposit of air pollutants in the lungs/airways and circulation, due to increased breathing frequency and minute ventilation, thus increasing the risk of cardiovascular disease. Thus, determining the tradeoff between the health benefits of physical activity and the potential harmful effects of increased exposure to air pollution during physical activity has important public health consequences. In the present comprehensive review, we analyzed evidence from human and animal studies on the combined effects of physical activity and air pollution on cardiovascular and other health outcomes. We further report on pathophysiological mechanisms underlying air pollution exposure, as well as the protective effects of physical activity with a focus on oxidative stress and inflammation. Lastly, we provide mitigation strategies and practical recommendations for physical activity in areas with polluted air.