Hot water immersion induces an acute cytokine response in cervical spinal cord injury

Purpose: The dysfunctional sympathetic nervous system in individuals with cervical spinal cord injury (CSCI) impairs adrenergic responses and may, therefore, contribute to the blunted post-exercise cytokine response. The purpose of this study was to investigate an alternative way to exercise to induce an acute cytokine response by passive core temperature elevation in CSCI. Methods: Seven male participants with a motor complete CSCI and 8 male able-bodied controls were immersed for 60 min in water set at a temperature 2 °C above the individuals’ resting oesophageal temperature. Blood was collected pre, post, and every hour up to 4 h post-immersion. Results: Hot water immersion resulted in an IL-6 plasma concentration mean increase of 133 ± 144 % in both groups (P = 0.001). On a group level, IL-6 plasma concentrations were 68 ± 38 % higher in CSCI (P = 0.06). In both groups, IL-8 increased by 14 ± 11 % (P = 0.02) and IL-1ra by 18 ± 17 % (P = 0.05). Catecholamine plasma concentrations were significantly reduced in CSCI (P < 0.05) and did not increase following immersion. Conclusions: Passive elevation of core temperature acutely elevates IL-6, IL-8 and IL-1ra in CSCI despite a blunted adrenergic response, which is in contrast to earlier exercise interventions in CSCI. The present study lays the foundation for future studies to explore water immersion as an alternative to exercise to induce an acute cytokine response in CSCI.