Abstract
Exercise can stimulate catabolic inflammatory cytokines even in healthy children. For patients with cystic fibrosis (CF), this may be problematic because 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 (IGF-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 control subjects (11.6 +/- 0.5 yr of age, NS). Subjects performed brief intermittent, constant work rate protocol (scaled to each individual's exercise capacity) with blood and urine sampling. Peak V O(2) was correlated with IGF-I (r = 0.68, p < 0.01) in control subjects but not in subjects with CF. In subjects with CF, baseline IL-6 was 79% greater (p < 0.05) and IGF-I was 47% lower than in control subjects (p < 0.05). Post hoc analysis revealed a progressive 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 patients 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). Qualitatively similar results were observed for TNF-alpha. Exercise also significantly increased IGFBP-1 in both control subjects and subjects with CF. Brief exercise can increase even chronically elevated inflammatory mediators in CF, and this response may be attenuated by ibuprofen.
Highlights
We examined fitness and the response to brief exercise of interleukin-6 (IL-6), tumor necrosis factor-␣ (TNF-␣), insulinlike growth factor-I (IGF-I), and IGF binding protein-1 (IGFBP-1) in 14 subjects with cystic fibrosis (CF) (10.5 Ϯ 0.8 yr of age), 9 of whom were treated with ibuprofen, and 14 healthy control subjects (11.6 Ϯ 0.5 yr of age, NS)
Our data corroborated recent findings by other investigators of reduced circulating IGF-I and elevated inflammatory cytokines in subjects with CF [24,25,26], our study failed to support the hypothesis that the inflammatory response to brief exercise was blunted in subjects with CF
A post hoc analysis suggested that the increase in IL-6 and TNF-␣ after exercise was ordered, with the highest values found in subjects with CF not receiving ibuprofen, lower in subjects with CF treated with ibuprofen, and lowest in control subjects
Summary
Exercise can stimulate catabolic inflammatory cytokines even in healthy children. We examined fitness and the response to brief exercise of interleukin-6 (IL-6), tumor necrosis factor-␣ (TNF-␣), insulinlike growth factor-I (IGF-I), and IGF binding protein-1 (IGFBP-1) in 14 subjects with CF (10.5 Ϯ 0.8 yr of age), 9 of whom were treated with ibuprofen, and 14 healthy control subjects (11.6 Ϯ 0.5 yr of age, NS). We predicted that the inflammatory response to acute exercise in children with CF would be depressed because the subjects with CF have chronically elevated TNF-␣ and IL-6, which could chronically stimulate anti-inflammatory mechanisms such as increased IL-1 receptor antagonist (IL-1ra).
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