Clinical utility of serum glial fibrillary acidic protein in glial neoplasm

Integrating Rapid Evaporative Ionization Mass Spectrometry Classification with Matrix-Assisted Laser Desorption Ionization Mass Spectrometry Imaging and Liquid Chromatography-Tandem Mass Spectrometry to Unveil Glioblastoma Overall Survival Prediction

Glioblastoma multiforme (GBM) is a highly aggressive brain cancer with a median survival of 15 months. Despite advancements in conventional treatment approaches such as surgery and chemotherapy, the prognosis remains poor. This study investigates the use of rapid evaporative ionization mass spectrometry (REIMS) for real-time overall survival time classification of GBM samples and uses matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) to compare lipidomic differences within GBM tumors. A total of 45 GBM biopsies were analyzed to develop a survival prediction model for IDH-wild type GBM. REIMS patterns from 28 patients were classified with a 97.7% correct classification rate, identifying key discriminators between short-term (0-12 months) and prolonged (>12 months) survivors. Cross-validation with additional samples showed that the model correctly classified short-term and prolonged survival with 66.7 and 69.4% accuracy, respectively. MALDI-MSI was performed to confirm the discriminators derived from REIMS data. Results indicated 42 and 33 discriminating features for short-term and prolonged survival, respectively. Proteomic profiling was performed by isolating tumor regions via laser-capture microdissection (LMD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Subsequently, 1387 proteins were identified, of which 79 were significantly altered. In conclusion, this study shows that REIMS rapidly predicts glioblastoma survival times based on lipidomic profiles during electrosurgical dissection. MALDI-MSI confirmed that these differences were specific to the tumor region in the glioblastoma sections. LMD-guided LC-MS/MS-based proteomics revealed significantly altered pathways between short-term and prolonged survival. This research, including the comprehensive predictive survival model for GBM, could guide tumor resection surgeries based on accurate real-time tumor tissue identification as well as provide insights into overall survival mechanisms, possibly related to therapy response.

Near infrared-emitting carbon dots for the detection of glial fibrillary acidic protein (GFAP): a non-enzymatic approach for the early identification of stroke and glioblastoma

Immunoassay techniques are widely recognized for their sensitivity and selectivity in biomarker detection; however, their high cost, time-consuming protocols and limited stability often pose significant limitations. In this study, we address these challenges by developing an antibody-free fluorescent platform for the detection of glial fibrillary acidic protein (GFAP), a biomarker released from astrocytes, which plays a critical role in neurological diseases such as ischemic stroke and glioblastoma (GBM). Glutamic acid (GA), a neurotransmitter prevalent in the brain, was selected to quench a near-infrared (NIR) emitting carbon dot-based probe, exploiting the potential interaction between GA and GFAP. The probe demonstrated a turn-on response towards GFAP in the presence of various co-existing biomolecules and ions with a detection limit of 1.8 pg mL-1. A real sample assay conducted in human serum further validated the performance of the probe, achieving a recovery rate of 85% to 97%, underscoring the potential of the probe as a reliable and cost-effective tool for GFAP detection in clinical settings.

Circulating Brain Injury Biomarkers for Predicting Outcomes Following Elective Neurosurgery: A Scoping Review

OBJECTIVE

There is a need for refined methods to detect and quantify brain injuries that may be undetectable by magnetic resonance imaging and neurologic examination. This review evaluates the potential efficacy of circulating brain injury biomarkers for predicting outcomes following elective neurosurgical procedures.

METHODS

A comprehensive search was conducted using the Cochrane, PubMed, and Scopus databases.

RESULTS

Analysis of 23 relevant studies revealed that specific biomarkers, including glial fibrillary acidic protein, neurofilament light chain, neuron-specific enolase, S100B, and tau, are significantly associated with the extent of brain injury and could potentially predict postsurgical outcomes. The evaluated studies described intracranial tumor surgeries and miscellaneous neurosurgical interventions and demonstrated the complex relationship between biomarker levels and patient outcomes.

CONCLUSIONS

Circulating brain injury biomarkers show promise for providing objective insights into the extent of perioperative brain injury and improving prognostication of postsurgical outcomes. However, the heterogeneity in study designs and outcomes along with the lack of standardized biomarker thresholds underscore the need for further research.

Glial fibrillary acidic protein, neurofilament light, matrix metalloprotease 3 and fatty acid binding protein 4 as non-invasive brain tumor biomarkers

BACKGROUND

Gliomas are aggressive malignant tumors, with poor prognosis. There is an unmet need for the discovery of new, non-invasive biomarkers for differential diagnosis, prognosis, and management of brain tumors. Our objective is to validate four plasma biomarkers - glial fibrillary acidic protein (GFAP), neurofilament light (NEFL), matrix metalloprotease 3 (MMP3) and fatty acid binding protein 4 (FABP4) - and compare them with established brain tumor molecular markers and survival.

METHODS

Our cohort consisted of patients with benign and malignant brain tumors (GBM = 77, Astrocytomas = 26, Oligodendrogliomas = 23, Secondary tumors = 35, Meningiomas = 70, Schwannomas = 15, Pituitary adenomas = 15, Normal individuals = 30). For measurements, we used ultrasensitive electrochemiluminescence multiplexed immunoassays.

RESULTS

High plasma GFAP concentration was associated with GBM, low GFAP and high FABP4 were associated with meningiomas, and low GFAP and low FABP4 were associated with astrocytomas and oligodendrogliomas. NEFL was associated with progression of disease. Several prognostic genetic alterations were significantly associated with all plasma biomarker levels. We found no independent associations between plasma GFAP, NEFL, FABP4 and MMP3, and overall survival. The candidate biomarkers could not reliably discriminate GBM from primary or secondary CNS lymphomas.

CONCLUSIONS

GFAP, NEFL, FABP4 and MMP3 are useful for differential diagnosis and prognosis, and are associated with molecular changes in gliomas.

GFAP as Astrocyte-Derived Extracellular Vesicle Cargo in Acute Ischemic Stroke Patients-A Pilot Study

The utility of serum glial fibrillary acidic protein (GFAP) in acute ischemic stroke (AIS) has been extensively studied in recent years. Here, we aimed to assess its potential role as a cargo protein of extracellular vesicles (EVs) secreted by astrocytes (ADEVs) in response to brain ischemia. Plasma samples from eighteen AIS patients at 24 h (D1), 7 days (D7), and one month (M1) post-symptoms onset, and nine age, sex, and cardiovascular risk factor-matched healthy controls were obtained to isolate EVs using the Exoquick ULTRA EV kit. Subsets of presumed ADEVs were identified further by the expression of the glutamate aspartate transporter (GLAST) as a specific marker of astrocytes with the Basic Exo-Flow Capture kit. Western blotting has tested the presence of GFAP in ADEV cargo. Post-stroke ADEV GFAP levels were elevated at D1 and D7 but not M1 compared to controls (p = 0.007, p = 0.019, and p = 0.344, respectively). Significant differences were highlighted in ADEV GFAP content at the three time points studied (n = 12, p = 0.027) and between D1 and M1 (z = 2.65, p = 0.023). A positive correlation was observed between the modified Rankin Scale (mRS) at D7 and ADEV GFAP at D1 (r = 0.58, p = 0.010) and D7 (r = 0.57, p = 0.013), respectively. ADEV GFAP may dynamically reflect changes during the first month post-ischemia. Profiling ADEVs from peripheral blood could provide a new way to assess the central nervous system pathology.

GFAP serves as a structural element of tunneling nanotubes between glioblastoma cells and could play a role in the intercellular transfer of mitochondria

Tunneling nanotubes (TNTs) are long F-actin-positive plasma membrane bridges connecting distant cells, allowing the intercellular transfer of cellular cargoes, and are found to be involved in glioblastoma (GBM) intercellular crosstalk. Glial fibrillary acid protein (GFAP) is a key intermediate filament protein of glial cells involved in cytoskeleton remodeling and linked to GBM progression. Whether GFAP plays a role in TNT structure and function in GBM is unknown. Here, analyzing F-actin and GFAP localization by laser-scan confocal microscopy followed by 3D reconstruction (3D-LSCM) and mitochondria dynamic by live-cell time-lapse fluorescence microscopy, we show the presence of GFAP in TNTs containing functional mitochondria connecting distant human GBM cells. Taking advantage of super-resolution 3D-LSCM, we show the presence of GFAP-positive TNT-like structures in resected human GBM as well. Using H2O2 or the pro-apoptotic toxin staurosporine (STS), we show that GFAP-positive TNTs strongly increase during oxidative stress and apoptosis in the GBM cell line. Culturing GBM cells with STS-treated GBM cells, we show that STS triggers the formation of GFAP-positive TNTs between them. Finally, we provide evidence that mitochondria co-localize with GFAP at the tip of close-ended GFAP-positive TNTs and inside receiving STS-GBM cells. Summarizing, here we found that GFAP is a structural component of TNTs generated by GBM cells, that GFAP-positive TNTs are upregulated in response to oxidative stress and pro-apoptotic stress, and that GFAP interacts with mitochondria during the intercellular transfer. These findings contribute to elucidate the molecular structure of TNTs generated by GBM cells, highlighting the structural role of GFAP in TNTs and suggesting a functional role of this intermediate filament component in the intercellular mitochondria transfer between GBM cells in response to pro-apoptotic stimuli.