Usefulness of serum interleukin-33 as a prognostic marker of severe traumatic brain injury

Background: Interleukin-33 is recently identified as a brain injury biomarker. We determined whether serum interlerukin-33 concentrations are associated with inflammation, severity and prognosis after traumatic brain injury (TBI). Methods: We detected serum interlerukin-33 concentrations of 102 healthy controls and 102 severe TBI patients, as well as serum concentrations of 3 inflammatory biomarkers (interleukin-6, tumor necrosis factor-alpha and C-reactive protein) and 7 cell-specific proteins (myelin basic protein, glial fibrillary astrocyte protein, S100B, neuron-specific enolase, phosphorylated axonal neurofilament subunit H, Tau and ubiquitin carboxyl-terminal hydrolase L1) in 102 severe TBI patients. The recorded poor prognosis variables included acute lung injury, acute traumatic coagulopathy, progressive hemorrhagic injury, posttraumatic cerebral infarction and six-month mortality and poor outcome (Glasgow score of 1-3). Results: Median interlerukin-33 concentration of patients (692 pg/mL) was substantially raised, as compared to controls. Interlerukin-33 concentrations were significantly correlated with Glasgow coma scale (GCS) score and the preceding biomarkers concentrations. Interlerukin-33 concentration > 692 pg/mL emerged as an independent prognostic predictor and its discriminatory capability exceeded those of the above-mentioned inflammatory biomarkers concentrations and was in the range of GCS scores and the aforementioned cell-specific proteins concentrations. Conclusion: Ascending serum interlerukin-33 concentrations could reflect inflammation, severity and worse prognosis following TBI.