The Effect of Exercise on Serum Cytokines Soluble Cytokine Receptors.

Cytokines mediate many acute and chronic responses to exercise through interaction with their membrane-bound receptor(s). However, in addition to the cytokines themselves, there exist soluble versions of cytokine receptors that may change in response to exercise. Soluble receptors represent an additional regulatory and modulatory layer of cytokine signaling. More attention to soluble cytokine receptors is needed to understand cytokine bioavailability and signaling following exercise. PURPOSE: To determine how cytokines and their soluble receptors change in the serum of both trained and untrained men after vigorous exercise. METHODS: Seven endurance-trained and five untrained men (N=12) participated in this study. Anthropometrics, cardiorespiratory fitness (e.g., VO2 peak) and cardiorespiratory compensation point (second ventilarory threshold: VT2) were assessed during baseline testing. At the experimental session, participants performed 1 hour of cycling at a workload that corresponded with their VT2. Blood samples were obtained at pre- and 3 hours post-exercise. The serum concentrations of 10 cytokines and 12 soluble cytokine receptors were measured using a MAGPIX multiplexing system. RESULTS: In the untrained group, several pro-inflammatory cytokines, including IL-4R, IL-6, TNF-α, IL-1β, CCL2, and VEGF-A were significantly increased, while the anti-inflammatory cytokine IL-10 was significantly decreased. In contrast, the trained group showed minimal changes in cytokine levels except for a significant increase in IL-10. Regarding soluble cytokine receptors, untrained individuals experienced a decrease in soluble GP130, IL-6R, and VEGFR3, alongside an increase in soluble VEGFR1 and IL-4R levels. Conversely, in trained participants, the majority of soluble receptors increased, including sGP130, sIL-1RII, sIL-6R, sTNFRI, and sTNFRIII, suggesting a regulatory effect on pro-inflammatory cytokine signaling in the trained group. CONCLUSION: Our results indicate that endurance exercise may enhance regulatory mechanisms governing cytokine signaling, thereby limiting inflammatory responses following vigorous exercise, as evidenced by reduced inflammatory cytokine production and decreased cytokine bioavailability via an upregulation of soluble receptors.