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- Title
Amino Acid Metabolism and Protein Turnover in Lean and Obese Humans During Exercise--Effect of IL-6 Receptor Blockade.
- Authors
Trinh, Beckey; Peletier, Merel; Simonsen, Casper; Plomgaard, Peter; Karstoft, Kristian; Pedersen, Bente Klarlund; van Hall, Gerrit; Ellingsgaard, Helga
- Abstract
Context: Interleukin-6 (IL-6) is implicated in skeletal muscle wasting and in regulating skeletal muscle hypertrophy in the healthy state. Objective: This work aimed to determine the role of IL-6 in regulating systemic protein and amino acid metabolism during rest, exercise, and recovery in lean and obese humans. Methods: In a nonrandomized, single-blind design, 12 lean and 9 obese individuals were infused first with 0.9% saline (Saline), secondly with the IL-6 receptor antibody tocilizumab (Acute IL-6R ab), and 21 days later with saline while still under tocilizumab influence (Chronic IL-6R ab). Outcome measures were determined before, during, and after 90 minutes of exercise at 40% Wattmax by isotope dilution technique, using primed continuous infusion of L-[ring-D5]phenylalanine and L-[D2]tyrosine. Main outcomes measures included systemic protein turnover and plasma amino acid concentrations. Results: We saw no effect of acute or chronic IL-6 receptor blockade on protein turnover. In lean individuals, chronic IL-6 receptor blockade increased plasma concentrations of total amino acids (rest Δ + 186 μmol/L; 95% CI, 40-332; recovery Δ + 201 μmol/L; 95% CI, 55-347) and essential amino acids (rest Δ + 43 μmol/L; 95% CI, 12-76; recovery Δ + 45 μmol/L; 95% CI, 13-77) independently of exercise but had no such effect in obese individuals (total amino acids rest Δ + 63 μmol/L; 95% CI, -170 to 295, recovery Δ - 23 μmol/L, 95% CI, -256 to 210; essential amino acids rest Δ + 26 μmol/L; 95% CI, -21 to 73, recovery Δ + 11 μmol/L; 95% CI, -36 to 58). Conclusion: IL-6 receptor blockade has no effect on protein turnover in fasting lean and obese humans during rest, exercise, and recovery. Chronic IL-6 receptor blockade increases total and essential amino acid concentrations only in lean individuals.
- Subjects
AMINO acid metabolism; INTERLEUKIN-6; SKELETAL muscle
- Publication
Journal of Clinical Endocrinology & Metabolism, 2022, Vol 107, Issue 7, p1854
- ISSN
0021-972X
- Publication type
Article
- DOI
10.1210/clinem/dgac239