Extracranial sources of S100B do not affect serum levels

Area of Science:

• Biochemistry
• Neuroscience
• Clinical Diagnostics

Background:

• S100B protein is a key biomarker for central nervous system conditions, including blood-brain barrier disruption and brain injury.
• Concerns exist regarding extracranial S100B sources, particularly from adipose tissue, potentially confounding its clinical interpretation.
• Understanding S100B tissue specificity is crucial for validating its use as a reliable diagnostic marker.

Purpose of the Study:

• To characterize the tissue specificity of S100B protein expression across various human tissues.
• To assess the influence of potential extracranial S100B sources on serum S100B levels.
• To evaluate the diagnostic utility of S100B in the context of potential confounding factors.

Main Methods:

• ELISA and Western blot analyses were performed on nine human tissue types to determine S100B expression.
• Mass spectrometry was used to analyze S100B and related proteins in brain and adipose tissues.
• Serum S100B levels and dimer forms were quantified in 200 subjects, correlating with Body Mass Index (BMI).

Main Results:

• Brain tissue exhibited the highest S100B levels by ELISA, with comparable levels found in skeletal muscle via Western blot.
• Mass spectrometry confirmed S100B in brain and adipose tissue, alongside S100A1.
• No significant relationship was observed between BMI and serum S100B levels in the study cohort.

Conclusions:

• Extracranial S100B sources do not significantly affect serum S100B levels.
• The diagnostic and negative predictive values of S100B for neurological conditions remain robust in intact individuals.
• S100B protein is a reliable biomarker for brain injury and blood-brain barrier integrity.