High Mobility Group Box 1: A Potential Biomarker For Post-Subarachnoid Hemorrhage Complications In Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is associated with the highest morbidity and mortality among all stroke subtypes. Endovascular coiling and neurosurgical clipping can successfully obliterate bleeding aneurysms from the circulation in almost all cases. Despite successful obliteration of the bleeding aneurysm, the clinical outcome in these patients is still poor. In a significant proportion of patients, the main reasons for poor outcome are occurrence of life-threatening complications including cerebral vasospasm (CVS), delayed cerebral ischemia (DCI), and systemic infections. Biomarkers in the systemic circulation or cerebrospinal fluid (CSF) may be useful to predict the occurrence of these complications and to provide timely treatment. Well-established and validated biomarkers for the diagnosis and prognosis of post-SAH inflammation in different complications and clinical outcomes in SAH are scarce and unspecific. Molecules released early in the pathophysiology of SAH might be of greater significance. High mobility group box-1 (HMGB1), a prototypical damage-associated molecular pattern molecule (DAMP), is released early after SAH and is known to upregulate inflammation after its extracellular release from damaged, stressed, and necrotic cells. We have identified HMGB1 as a specific and potential biomarker for CVS. This mini-review explores the biomarker potential of HMGB1 in the context of post-SAH complications and clinical outcome.