Inflammatory and Satellite Cells in the Quadriceps of Patients With COPD and Response to Resistance Training

Background: Quadriceps dysfunction in COPD may be mediated by inflammatory mechanisms or impaired satellite cell function. Resistance training is of proven efficacy in these patients, but data on muscle inflammatory and satellite cell response to resistance exercise in COPD are lacking. We aimed to examine the inflammatory and satellite cell profile of the quadriceps in patients with COPD and healthy control subjects at rest and after acute and chronic resistance exercise. Methods: Seventeen patients with COPD and 10 healthy control subjects underwent 8 weeks of bilateral lower-limb, high-intensity resistance training, thrice weekly, on an isokinetic dynamometer. Quadriceps muscle biopsy specimens from the dominant thigh were obtained at baseline, 24 h following the first exercise bout, and after 8 weeks 24 h after the last exercise bout. Glycol methacrylate-embedded muscle biopsy specimens were analyzed using immunohistochemistry to identify neutrophils, macrophages, and satellite cells. Results: Neutrophils were significantly elevated in the quadriceps of patients with COPD at baseline compared with healthy control subjects (P = .03). Inflammatory cells were increased significantly at 24 h in both groups but were similar to baseline values at week 8, with no difference detectable between healthy control subjects and patients with COPD. Satellite cell numbers were comparable between patients and control subjects at baseline, tended to increase at 24 h, and remained elevated at week 8. Conclusions: Inflammatory cells are elevated in the resting quadriceps of patients with COPD. Acute resistance exercise leads to an inflammatory myositis, which is attenuated with regular training. Satellite cells in patients and control subjects are comparable and are increased in response to exercise.