Impact of training status on LPS-induced acute inflammation in humans

The aim of the present study was to examine the impact of training status on the ability to induce a lipopolysaccharide (LPS)-induced inflammatory response systemically as well as in skeletal muscle (SkM) and adipose tissue (AT) in human subjects. Seventeen young (23.8 ± 2.5 yr of age) healthy male subjects were included in the study with eight subjects assigned to a trained (T) group and nine subjects assigned to an untrained (UT) group. On the experimental day, catheters were inserted in the femoral artery and vein of one leg for blood sampling and a bolus of 0.3 ng LPS/kg body wt was injected into an antecubital vein in the forearm. Femoral arterial blood flow was measured by ultrasound Doppler, and arterial and venous blood samples were drawn before (Pre) LPS injection and 30, 60, 90, and 120 min after the LPS injection. Vastus lateralis muscle and abdominal subcutaneous AT biopsies were obtained Pre and 60 and 120 min after the LPS injection. LPS increased the systemic plasma TNFα and IL-6 level as well as the TNFα and IL-6 mRNA content in SkM and AT of both UT and T. However, whereas the LPS-induced inflammatory response in SkM was enhanced in T subjects relative to UT, the inflammatory response systemically and in AT was somewhat delayed in T subjects relative to UT. The present findings highlight that training status affects the ability to induce a LPS-induced acute inflammatory response in a tissue-specific manner.