Interleukin-6 and interleukin-10 plasma levels and mRNA expression in polytrauma patients

Host response to polytrauma occasionally has unpredictable outcomes. Immune response is a major factor influencing patient's outcome. This study evaluated the interaction of two main cytokines in immune response after major trauma, specifically interleukin-6 (IL-6) and interleukin-10 (IL-10). Plasma level of these cytokines is determined by mRNA expression of these cytokines genes which may decide the outcome of polytrauma patients.

This prospective multicenter trial held at four trauma centers enrolled 54 polytrauma patients [Injury Severity Score (ISS) ≥ 16]. Plasma levels and mRNA expression of IL-6 and IL-10 were measured for 5 days after trauma. Clinical evaluation was conducted to observe whether patients endured multiple organ dysfunction syndrome (MODS) and death. MODS evaluation was performed using sequential organ failure assessment (SOFA). Trauma load which in this study is represented with ISS, plasma level, expression of cytokine genes and patient's outcome were examined with correlation test and statistical analysis.

The elevated IL-6/IL-10 ratio indicated increased activity of systemic inflammation response, especially pro-inflammation response which bears higher probability of progressing to MODS and death. The decline of IL-6/IL-10 ratio with heavy trauma load (ISS > 30) showed that compensatory anti-inflammation response syndrome (CARS) state was more dominant than systemic inflammatory response syndrome (SIRS), indicating that malfunction and failure of immune system eventually lead to MODS and deaths. The statistical significance in plasma level of cytokines was found in the outcome group which was defined as bearing a low trauma load but mortality.

The pattern of cytokine levels in inflammation response has great impact on the outcome of polytrauma patients. Further study at the genetic level is needed to investigate inflammation process which may influence patient's outcome.