Fitness, acute exercise, and anabolic and catabolic mediators in cystic fibrosis

Exercise can stimulate catabolic inflammatory cytokines even in healthy chi ldren. For patients with cystic fibrosis (CF), this may be problematic beca use CF is characterized by increased inflammation and suppressed growth. We examined fitness and the response to brief exercise of interleukin-6 (IL-6 ), tumor necrosis factor-alpha (TNF-alpha), insulinlike growth factor-I (IG F-I), and IGF binding protein-1 (IGFBP-1) in 14 subjects with CF (10.5 +/- 0.8 yr of age),9 of whom were treated with ibuprofen, and 14 healthy contro l subjects (11.6 +/- 0.5 yr of age, NS). Subjects performed brief intermitt ent, constant work rate protocol (scaled to each individual's exercise capa city) with blood and urine sampling. Peak Vo(2) was correlated with IGF-I ( r = 0.68, p < 0.01) in control subjects but not in subjects with CF. In sub jects with CF, baseline IL-6 was 79% greater (p < 0.05) and IGF-I was 47% l ower than in control subjects (p < 0.05). Post hoc analysis revealed a prog ressive increase in the IL-6 response to exercise, with the lowest increase observed in control subjects (11.8 +/- 4.6 pg/L/kJ), higher increases in p atients with CF treated with ibuprofen (23.4 +/- 7.7 pg/L/kJ), and highest in subjects with CF not receiving ibuprofen (29.2 +/- 7.5 pg/L/kJ)- Qualita tively similar results were observed for TNF-a. Exercise also significantly increased IGFBP-1 in both control subjects and subjects with CF. Brief exe rcise can increase even chronically elevated inflammatory mediators in CF, and this response may be attenuated by ibuprofen.