Biochemical Markers for Brain Damage:

The Role of S100b Protein Biomarker in Brain Death: A Literature Review

Brain death (BD) represents the irreversible loss of all brain functions, including the brainstem, and is equivalent to clinical death established by neurological criteria. However, clinical diagnosis, mainly based on the absence of primary reflexes post-acute brain injury, remains a challenge in hospital settings. The S100 calcium-binding protein beta (S100b) is used to monitor brain injuries, as recommended by neurotrauma care guidelines in some countries. Its levels are associated with severity and mortality, particularly after traumatic brain injury (TBI) and cerebral hemorrhage. The evaluation of S100b levels in investigating brain death is promising; however, aspects such as cutoff values remain to be elucidated. This paper reviews the literature on the use of S100b as a biomarker in diagnosing brain death. It is noteworthy that there is still no defined cutoff for S100b levels in confirming brain death. Additionally, when considering the use of S100b in emergency situations, a point-of-care methodology should be established to support clinical decision-making quickly and easily in the early identification of patients who are more likely to progress to brain death. In this context, S100b levels may assist in establishing the diagnosis of brain death, complementing existing clinical evidence. This, in turn, can optimize and qualify the organ donation process, reducing costs with ineffective therapies and minimizing the suffering of the families involved.

Comparison of predictive powers of S100B and cell-free plasma DNA values in intensive care unit patients with intracranial hemorrhage

PURPOSE

To investigate predictive powers of S100B and cell-free DNA (cfDNA) levels in patients in the intensive care unit (ICU) who have with intracranial hemorrhage (ICH) for prognosis.

METHODS

Ninety-nine patients diagnosed with ICH were included in the study. The blood samples were drawn on the day of admittance to ICU and again on the third day. Duration of stay in the ICU and mortality were recorded.

RESULTS

A positive correlation was determined between the values of S100B and cfDNA from both the analysis and the Acute Physiology and Chronic Health Evaluation II scores. For all patients, there was a positive correlation between the duration of stay in the ICU and the values of S100B and cfDNA on the third day. The levels of both S100B and cfDNA in patients who died in the ICU were significantly higher than of those who survived on the day of admittance.

CONCLUSIONS

Both S100B and cfDNA values can be used as markers to predict the prognosis of ICU patients with ICH. However, S100B is more powerful for predicting the prognosis.

Fisetin enhances behavioral performances and attenuates reactive gliosis and inflammation during aluminum chloride-induced neurotoxicity

Aluminum (Al) is an environmental neurotoxin that affects cerebral functions and causes health complications. However, the role of Al in arbitrating glia homeostasis and pathophysiology remains obscure. Astrocyte, microglia activation (reactive gliosis), and associated inflammatory events play a decisive role in neurodegeneration and may represent a target for treating neurodegenerative disorders. In this study, we have analyzed the role of aluminum chloride (AlCl3) in causing reactive gliosis in the brain of mice and the ability of fisetin, a flavonoid to attenuate reactive gliosis and neuronal inflammation. Reports suggest that fisetin exerts antioxidant and anti-inflammatory actions. Fisetin at a dose of 15 mg/kg body weight was orally administered, daily (pre-treated for 4 weeks before AlCl3 induction and co-treated until experimental period of 8 weeks) to mice induced with AlCl3 (200 mg/kg b.wt./day/8 weeks, orally). Administration of AlCl3 developed behavioral deficits, triggered lipid peroxidation (LPO), compromised acetylcholine esterase (AChE) activity, and reduced the levels of superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), and reduced glutathione (GSH), and caused histologic aberrations. These effects were accompanied by increased expressions of Glial fibrillary acidic protein and ionized calcium-binding adapter molecule 1. Pro-inflammatory cytokines, such as tumor necrosis factor alpha, interleukin-1β, inducible nitric oxide synthase, were increased upon AlCl3 administration. AlCl3-induced alterations in the activities of SOD, CAT, GST, AChE and levels of GSH, LPO, activity of AChE, behavioral deficits, histologic aberrations, reactive gliosis, and inflammatory niche were attenuated on treatment with fisetin. Collectively, our results indicate that fisetin exerts neuroprotection against AlCl3-induced brain pathology.

Reliability of S100B in predicting severity of central nervous system injury

S100B is a protein biomarker that reflects CNS injury. It can be measured in the CSF or serum with readily available immunoassay kits. The excellent sensitivity of S100B has enabled it to confirm the existence of subtle brain injury in patients with mild head trauma, strokes, and after successful resuscitation from cardiopulmonary arrest. The extent of S100B elevation has been found to be useful in predicting clinical outcome after brain injury. Elevations of S100B above certain threshold levels might be able to reliably predict brain death or mortality. A normal S100B level reliably predicts the absence of significant CNS injury. The specificity of S100B levels as a reflection of CNS injury is compromised by the findings that extra-cranial injuries can lead to elevations in the absence of brain injury. This potential problem can most likely be avoided by measuring serial S100B levels along with other biomarkers and carefully noting peripheral injuries. Serum markers GFAP and NSE are both more specific for CNS injury and have little to no extra-cranial sources. Sustained elevations of S100B over 24 h along with elevations of GFAP and NSE can more reliably predict the extent of brain injury and clinical outcomes. In the future, S100B measurements might reliably predict secondary brain injury and enable physicians to initiate therapeutic interventions in a timelier manner. S100B levels have been shown to rise hours to days before changes in ICP, neurological examinations, and neuroimaging tests. S100B levels may also be used to monitor the efficacy of treatments.

Serum S100beta protein in children with acute recurrent headache: a potentially useful marker for migraine

OBJECTIVE

To examine the role of glia-derived S100beta protein and to evaluate its use as a biochemical marker in childhood acute recurrent headache.

METHODS

Twenty-five patients with acute recurrent headache (according to International Headache Society criteria) from our department's Headache Clinic were studied. Blood samples for measurement of serum S100beta were drawn: (1) < or = 3-hour post pain attack from our patients and (2) from 23 healthy controls.

RESULTS

Of the 25 patients evaluated, 15 suffered from migraine and 10 from tension-type headache (TTH). Statistical analysis of the mean values of S100beta levels demonstrated a significant elevation in children with migraine headache, with values higher than those of both children with TTH and controls (P = .001).

CONCLUSIONS

Our data suggest a direct relation between childhood migraine attacks and increased production of glial S100beta protein. Serum S100beta determination may be a useful biochemical marker for migraine in acute recurrent headache in childhood.