Although regular exercise-training improves immune/inflammatory status, the influence of air pollutants exposure during outdoor endurance training compared to a sedentary lifestyle has not yet been clarified. This study aimed to compare the immune/inflammatory responses in the airways of street runners and sedentary people after acute and chronic particulate matter (PM) exposure. Forty volunteers (street runners (RUN, n = 20); sedentary people (SED, n = 20)) were evaluated 1 (acute) and 10 (chronic) weeks after PM exposure. Cytokines [interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, IL-13, and IL-17A] in nasal lavage fluid, salivary antibacterial peptides (lactoferrin (LTF), cathelicidin (LL-37), defensin-α 1–3), and secretory immunoglobulin A (SIgA), plasma club cell protein (CC16), and fractional exhaled nitric oxide (FeNO) were analyzed. After acute exposure, the RUN group showed lower levels of IL-13, IL-10, and FeNO, but higher defensin-α than the SED group. After chronic exposure, the RUN group showed elevation of IFN-γ, IL-10, IL-17A, and a decrease of FeNO levels, whereas the SED group showed elevation of TNF-α, IL-6, IL-10, and a decrease of IL-13 levels. Comparing these groups, the RUN group showed higher levels of SIgA and LTF, and lower FeNO levels than the SED group. In relation to the Th immune response analysis after acute and chronic PM exposure, the RUN group showed a pattern associated with Th1, while in the SED group, a Th2 pattern was found. Both groups showed also a Th17 immune response pattern. Our results allow us to suggest that the immune/inflammatory status of the respiratory tract after acute and chronic PM exposure was improved by the long-standing regular practice of outdoor endurance exercise compared to a sedentary lifestyle.

Physical exercise promotes many health benefits. However, its effects are not well known in a polluted environment. Thus, this study aimed to compare upper airway inflammatory responses between street runners and sedentary individuals. Twenty-eight volunteers were recruited: runners (n = 14) and sedentary individuals (n = 14), who lived and worked in the same metropolitan area of São Paulo, Brazil. Particulate matter (PM) levels were monitored ten weeks before winter (low PM levels) and ten weeks after the beginning of winter (high PM levels) [PM₁₀ (p < 0.0001) and PM_2.5 (p < 0.0001)]. The cytokines (TNF-α, IL-6, IL-10, and IL-17A) levels in the nasal lavage and fractional exhaled nitric oxide (FeNO) were taken at the beginning of the winter (baseline) and ten weeks afterwards (after ten weeks of high PM exposure). IL-6 concentration increased in both runners (p = 0.037) and sedentary individuals (p = 0.027) after high PM exposure compared to the baseline. IL-10 concentration increased in sedentary individuals (p = 0.037) while IL-17A levels were increased in runners (p = 0.001) after high PM exposure compared to the baseline. FeNO levels decreased in runners (p = 0.025) after high PM exposure compared to the baseline. Outdoor endurance training acts as an inducer of a differentiated immune response in the upper airways of runners compared to individuals with a sedentary lifestyle from the same community after elevated PM exposure.