Neuroinflammation is Associated with Brain Extracellular TAU-Protein Release After Spontaneous Subarachnoid Hemorrhage
Current Drug Targets | December 2017
Schiefecker AJ, Dietmann A, Beer R, Pfausler B, Lackner P, Kofler M, Fischer M, Broessner G, Sohm F, Mulino M, Thome C, Humpel C, Schmutzhard E and Helbok R.
Curr Drug Targets. 2017;18:1408-1416.
Introduction: Animal data suggest an association between neuroinflammation and secondary brain injury including axonal injury after aneurysmal subarachnoid hemorrhage (aSAH). We sought to study the association between brain extracellular interleukin (IL)-6 and TAU-protein levels as a surrogate marker for neuroinflammation and axonal injury in patients with poor grade aSAH.Methods: Prospectively collected data from 26 consecutive poor-grade aSAH patients with multimodal neuromonitoring including cerebral microdialysis (CMD) were retrospectively analyzed. IL-6 and TAU-protein levels were analyzed using ELISA from a single CMD-sample every 24 hours and correlated with brain metabolic and hemodynamic parameters. Patients were dichotomized to highgrade (N=10) or low-grade (N=16) neuroinflammation according to their median CMD-IL-6 levels. Data were analyzed using generalized estimating equations to account for multiple within-subject measurements.Results: Perilesional probe location (P=0.02) and aSAH related intracerebral hemorrhage (aICH) volume (P=0.003) at admission were associated with high-grade neuroinflammation. Brain extracellular TAU-protein levels (P=0.001), metabolic distress and delayed cerebral infarction (DCI; P=0.001) were linked to high-grade neuroinflammation. Relative or absolute phosphor-TAU levels were not correlated with CMD-IL-6 levels. High-grade neuroinflammation was a predictor for worse outcome three months after ictus, independently from probe location, initial Hunt&Hess grade and age (P=0.01).Conclusion: Neuroinflammation after aSAH is associated with intraparenchymal bleeding, deranged cerebral metabolism and TAU-protein release. The impact of potential anti-inflammatory treatment strategies on secondary brain injury after aSAH has to be investigated in future studies.