Pastva A, Estell K, Schoeb TR, Atkinson TP, Schwiebert LM. J Immunol. 2004;172:4520–4526
Purpose of the Study.
To determine the effect of moderate aerobic exercise on pulmonary inflammatory responses in a mouse model of atopic asthma.
BALB/cJ mice were assigned to 1 of 4 groups: sedentary and nonsensitized, sedentary and ovalbumin (OVA) sensitized, exercised and nonsensitized, and exercised and OVA sensitized. Sensitized mice were boosted with nebulized OVA for the duration of the study, and nonsensitized mice received nebulized saline. Mice assigned to the exercise group ran on a motorized treadmill 3 times a week for 4 weeks, for up to 45 minutes. Mice were euthanized 24 hours after completing the exercise regimen, and their lungs were fixed, stained, and assessed for the extent of the leukocytic infiltrate, epithelial cell hypertrophy, mucus production, and expression of adhesion molecules and the nuclear factor κB (NF-κB) subunit p65. Bronchoalveolar lavage (BAL) fluid was collected, and leukocyte counts and protein content were quantified. Cytokine and chemokine levels were quantified by enzyme-linked immunosorbent assay (ELISA). Serum was collected and analyzed for total IgE and OVA-specific IgE by ELISA.
Exercised, sensitized mice had a statistically significantly decreased cellular infiltrate, epithelial hyperplasia, and goblet cells and mucin production compared with sedentary, sensitized mice. Exercise also decreased the total BAL fluid protein in sensitized mice. Exercised, sensitized mice had significantly fewer macrophages, lymphocytes, neutrophils, and eosinophils in BAL fluid samples than sedentary, sensitized mice. Exercise also decreased KC (murine homolog of interleukin [IL]-8) levels in sensitized mice to the baseline levels observed in nonsensitized mice but had no effect on monocyte chemoattractant protein 1 levels. Exercise did not reduce intercellular adhesion molecule 1 expression but did reduce vascular cell adhesion molecule 1 expression in lung epithelium of sensitized mice. Exercise also decreased BAL fluid levels of the T-helper 2 cytokines, IL-4 and IL-5, by 13- and 3-fold, respectively. Exercised, sensitized mice had lower levels of OVA-specific IgE levels but not total IgE levels than sedentary, sensitized mice (P < .05). Exercise also decreased nuclear translocation of NF-κB, a molecule that is involved in transcriptional activation of inflammatory genes.
Moderate aerobic exercise attenuates airway inflammation by decreasing NF-κB activation. Aerobic exercise is a promising treatment for asthma.
Although several observational studies have suggested that aerobic exercise improves lung function and decreases asthma symptoms, it has been unclear if exercise had a direct effect on the pulmonary inflammatory response that is characteristic of asthma. The findings in this article, however, suggest that aerobic exercise may directly inhibit pulmonary inflammatory responses. Aerobic exercise would be an attractive, nonpharmacologic treatment option if proven to be effective in human trials.