Glial Fibrillary Acidic Protein (GFAP) is a key brain injury and neurodegeneration biomarker. It is found primarily in astrocytes, star-shaped glial cells in the central nervous system (CNS). GFAP is integral to the CNS's structural integrity, contributing to cell communication and maintaining the blood-brain barrier. Its expression increases significantly in response to CNS damage, making it a valuable indicator of astrocytic activation and neuronal injury.
GFAP is a type III intermediate filament protein that forms a part of the cytoskeleton in astrocytes. It supports the mechanical strength of astrocytes, facilitates their motility, and helps maintain the shape and volume of these cells. GFAP helps maintain the extracellular space and ion homeostasis in a healthy brain, which is crucial for proper neurotransmission and neural protection. The protein also plays a role in repairing the CNS after injury by forming the glial scar, which isolates and protects the injury site from the surrounding healthy tissue.
Elevated levels of GFAP in serum are associated with various neurological diseases, reflecting its release from damaged astrocytes. The detection of GFAP in serum provides a minimally invasive means to assess neurological damage and disease progression:
Traumatic Brain Injury (TBI): GFAP levels in the serum rise rapidly following TBI, correlating with the extent of tissue damage and astrocyte disruption. It assesses injury severity and predicts outcomes, helping clinicians decide on intervention strategies and rehabilitation protocols.
Stroke: In ischemic and hemorrhagic stroke, GFAP levels increase due to astrocytic injury and death. Monitoring GFAP can assist in diagnosing stroke types and severities, potentially guiding therapeutic decisions and predictive assessments.
Neurodegenerative Diseases: Conditions like Alzheimer’s disease and multiple sclerosis show elevated GFAP levels, indicating ongoing neuroinflammatory processes and astrocyte activation. GFAP is emerging as a biomarker for disease progression and response to therapies in these conditions.
Brain Tumors: Astrocytomas, including glioblastoma multiforme, express high levels of GFAP. Serum GFAP can be a noninvasive biomarker for monitoring tumor growth, responding to treatments, and detecting recurrences.
Autoimmune Encephalitis: GFAP can be elevated in autoimmune CNS disorders, reflecting astrocyte damage due to inflammatory processes. It helps diagnose and monitor the effectiveness of immunosuppressive therapies.
Serum GFAP levels are typically measured using immunoassays, such as ELISA or, more commonly, single-molecule array (Simoa) technology. These offer the sensitivity and specificity required to detect even low levels of this protein in peripheral blood. This method allows for routine monitoring without requiring invasive procedures like lumbar punctures.
