The Effect of Particulate Matter Exposure on the Inflammatory Airway Response of Street Runners and Sedentary People

LPS Response Is Impaired by Urban Fine Particulate Matter

Fine particulate matter (PM_2.5) is a complex mixture of components with diverse chemical and physical characteristics associated with increased respiratory and cardiovascular diseases mortality. Our study aimed to investigate the effects of exposure to concentrated PM_2.5 on LPS-induced lung injury onset. BALB/c male mice were exposed to either filtered air or ambient fine PM_2.5 in an ambient particle concentrator for 5 weeks. Then, an acute lung injury was induced with nebulized LPS. The animals were euthanized 24 h after the nebulization to either LPS or saline. Inflammatory cells and cytokines (IL-1β, IL-4, IL-5, IL-6, IL-10, IL-17, TNF) were assessed in the blood, bronchoalveolar lavage fluid (BALF), and lung tissue. In addition, lung morphology was assessed by stereological methods. Our results showed that the PM+LPS group showed histological evidence of injury, leukocytosis with increased neutrophils and macrophages, and a mixed inflammatory response profile, with increased KC, IL-6, IL-1β, IL-4, and IL-17. Our analysis shows that there is an interaction between the LPS nebulization and PM_2.5 exposure, differently modulating the inflammatory response, with a distinct response pattern as compared to LPS or PM_2.5 exposure alone. Further studies are required to explain the mechanism of immune modulation caused by PM_2.5 exposure.

Air Pollution and the Airways: Lessons from a Century of Human Urbanization

Since the industrial revolution, air pollution has become a major problem causing several health problems involving the airways as well as the cardiovascular, reproductive, or neurological system. According to the WHO, about 3.6 million deaths every year are related to inhalation of polluted air, specifically due to pulmonary diseases. Polluted air first encounters the airways, which are a major human defense mechanism to reduce the risk of this aggressor. Air pollution consists of a mixture of potentially harmful compounds such as particulate matter, ozone, carbon monoxide, volatile organic compounds, and heavy metals, each having its own effects on the human body. In the last decades, a lot of research investigating the underlying risks and effects of air pollution and/or its specific compounds on the airways, has been performed, involving both in vivo and in vitro experiments. The goal of this review is to give an overview of the recent data on the effects of air pollution on healthy and diseased airways or models of airway disease, such as asthma or chronic obstructive pulmonary disease. Therefore, we focused on studies involving pollution and airway symptoms and/or damage both in mice and humans.

Pulmonary Effects Due to Physical Exercise in Polluted Air: Evidence from Studies Conducted on Healthy Humans

Physical inactivity has caused serious effects on the health of the population, having an impact on the quality of life and the cost of healthcare for many countries. This has motivated government and private institutions to promote regular physical activity, which, paradoxically, can involve health risks when it is carried out in areas with poor air quality. This review collects information from studies conducted on healthy humans related to the pulmonary effects caused by the practice of physical activity when there is poor air quality. In addition, several challenges related to the technological and educational areas, as well as to applied and basic research, have been identified to facilitate the rational practice of exercise in poor air quality conditions.

Differential effects of intense exercise and pollution on the airways in a murine model

Background

Exercise-induced bronchoconstriction (EIB) is a transient airway narrowing, occurring during or shortly after intensive exercise. It is highly prevalent in non-asthmatic outdoor endurance athletes suggesting an important contribution of air pollution in the development of EIB. Therefore, more research is necessary to investigate the combination of exercise and pollutants on the airways.

Methods

Balbc/ByJ mice were intranasally challenged 5 days a week for 3 weeks with saline or 0.2 mg/ml diesel exhaust particles (DEP), prior to a daily incremental running session or non-exercise session. Once a week, the early ventilatory response was measured and lung function was determined at day 24. Airway inflammation and cytokine levels were evaluated in bronchoalveolar lavage fluid. Furthermore, innate lymphoid cells, dendritic cells and tight junction mRNA expression were determined in lung tissue.

Results

Submaximal exercise resulted in acute alterations of the breathing pattern and significantly improved FEV_0.1 at day 24. DEP exposure induced neutrophilic airway inflammation, accompanied with increased percentages of CD11b⁺ DC in lung tissue and pro-inflammatory cytokines, such as IL-13, MCP-1, GM-CSF and KC. Occludin and claudin-1(Cldn-1) expression were respectively increased and decreased by DEP exposure. Whereas, exercise increased Cldn-3 and Cldn-18 expression. Combining exercise and DEP exposure resulted in significantly increased SP-D levels in the airways.

Conclusion

DEP exposure induced typical airway neutrophilia, DC recruitment and pro-inflammatory cytokine production. Whereas, intensive exercise induced changes of the breathing pattern. The combination of both triggers resulted in a dysregulation of tight junction expression, suggesting that intensive exercise in polluted environments can induce important changes in the airway physiology and integrity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00401-6.

The Relationship of IL-8 and IL-10 Myokines and Performance in Male Marathon Runners Presenting Exercise-Induced Bronchoconstriction

At present, it is unclear which exercise-induced factors, such as myokines, could diminish the negative impact of the reduction in pulmonary function imposed by the exercise in question. In this study, we aim to evaluate the prevalence of exercise-induced bronchoconstriction (EIB) and also to investigate the effect of myokines in the performance of marathon runners presenting EIB or not. Thirty-eight male recreational marathon runners (age 38.8 [33-44], height 175.7 [172.0-180.3]; weight 74.7 [69.3-81.6]) participated in this study, and through spirometry tests, a prevalence of 23.6% of EIB was found, which is in agreement with the literature. The volunteers who tested positive to EIB (EIB+) presented lower maximum aerobic capacity compared to those who tested negative (EIB-) (EIB+ 44.02 [39.56-47.02] and EIB- 47.62 [44.11-51.18] p = 0.03). The comparison of plasma levels of IL-1β (EIB+ p = 0.296, EIB- p = 0.176, EIB+ vs. EIB- baseline p = 0.190 immediately after p = 0.106), IL-4 (undetectable), IL-6 (EIB+ p = 0.003, EIB- p ≤ 0.001, EIB+ vs. EIB- baseline p = 0.301 immediately after p = 0.614), IL-8 (EIB+ p = 0.003, EIB- p ≤ 0.001, EIB+ vs. EIB- baseline p = 0.110 immediately after p = 0.453), IL-10 (EIB+ p = 0.003, EIB- p ≤ 0.001, EIB+ vs. EIB- baseline p = 0.424 immediately after p = 0.876) and TNF-α (EIB+ p = 0.003, EIB- p ≤ 0.001, EIB+ vs. EIB- baseline p = 0.141 immediately after p = 0.898) were similar in both groups 24 h before and immediately after the marathon. However, negative correlations were found between the marathon finishing time and the levels of IL-8 (r = -0.81, p = 0.022), and IL-10 (r = -0.97, p ≤ 0.001) immediately after completing the marathon. In conclusion, for the first time, it is shown that the myokines IL-8 and IL-10 are related to improvement of the performance of marathon runners presenting EIB.