Exaggerated expression of skeletal muscle-derived interleukin-6, but not TNFalpha, in mice lacking interleukin-10

IL-10 reduces cytokine expression in non-muscle tissues, but its effect on skeletal muscle remains undefined. Therefore, we tested the hypothesis that endogenous IL-10 acts to reduce cytokines in the gastrocnemius muscle by comparing IL-6 and TNFalpha expression in wild-type (IL-10(+/+)) and IL-10 deficient (IL-10(-/-)) mice following an inflammatory insult induced by peripheral LPS. IL-6 mRNA expression increased following LPS for both IL-10(+/+) and IL-10(-/-) mice; the response was greater and prolonged in IL-10(-/-) mice. Muscle TNFalpha mRNA also increased, but without differences between genotypes. IL-6 protein concentrations were elevated by LPS with a greater and prolonged response for IL-10(-/-) mice, but TNFalpha did not change. These results provide the first in vivo evidence that endogenous IL-10 attenuates IL-6 expression by skeletal muscle in response to LPS.