Increased levels of interleukin-6, -8 and -10 are associated to fatal outcome in men with severe traumatic brain injury

Introduction: Traumatic brain injury (TBI) is the major cause of death among individuals between 1–45 years-old. The outcome of the TBI patients may be related to both the severity of the primary lesion and the extent of the secondary brain damage. Secondary brain damage is associated with neuroinflammatory phenomena, characterized by activation of microglia and astrocytes, damage to the blood-brain barrier and production of cytokines. Although increased cytokine production and cellular inflammation are clearly involved on the pathophysiology of TBI, no clear relationships have been established between measurements of cytokines and clinical outcome following TBI.

Objective: The present study was designed to examine which changes in cytokine levels (of IL-1b, IL-6, IL-8, IL-10, IL-12p70 and TNF-a) are associated with primary outcome (death or survival) and clinical measures following severe TBI in men.

Methods: The study group consisted of 24 male patients, victims of severe TBI. Venous blood samples were taken in the Intensive Care Unit (ICU) (study entry), 24 and 48 hours later. The plasma cytokine levels were assayed by flow cytometry. Severe TBI was associated with a 42% mortality rate. TBI patients had significant increase in the levels of all cytokines measured, except for IL-1b, compared to controls. Statistically significant increases in the IL- 10, 8 and 6 levels were observed in non-survivors TBI patients compared to survivors subgroup measured in the first sample (study entry) and in the subsequent sample (24 hours latter). There were no significant differences in IL-1b, TNF-a and IL-12p70 levels between survivors and non-survivors in any time investigated.

Conclusion: Our findings indicate that increased IL-10, 8 and 6 levels may constitute an early predictor of unfavorable outcome in severe TBI patients.