Neurological diseases are a major health concern, and brain injury is a typical pathological process in various neurological disorders. Different biomarkers in the blood or the cerebrospinal fluid are associated with specific physiological and pathological processes. They are vital in identifying, diagnosing, and treating brain injuries. In this review, we described biomarkers for neuronal cell body injury (neuron-specific enolase, ubiquitin C-terminal hydrolase-L1, αII-spectrin), axonal injury (neurofilament proteins, tau), astrocyte injury (S100β, glial fibrillary acidic protein), demyelination (myelin basic protein), autoantibodies, and other emerging biomarkers (extracellular vesicles, microRNAs). We aimed to summarize the applications of these biomarkers and their related interests and limits in the diagnosis and prognosis for neurological diseases, including traumatic brain injury, status epilepticus, stroke, Alzheimer's disease, and infection. In addition, a reasonable outlook for brain injury biomarkers as ideal detection tools for neurological diseases is presented.
Humans ; Biomarkers/cerebrospinal fluid* ; Nervous System Diseases/diagnosis* ; Brain Injuries/metabolism* ; Phosphopyruvate Hydratase/cerebrospinal fluid* ; Glial Fibrillary Acidic Protein/blood* ; S100 Calcium Binding Protein beta Subunit/blood* ; tau Proteins/cerebrospinal fluid* ; Ubiquitin Thiolesterase/blood* ; Myelin Basic Protein/cerebrospinal fluid* ; Neurofilament Proteins/blood* ; MicroRNAs/blood* ; Brain Injuries, Traumatic/metabolism*

OBJECTIVES: This study aimed to investigate the potential mediating role of plasma phosphorylated tau217 (p-tau217) in the association between periodontitis and mild cognitive impairment (MCI). METHODS: In this case-control study, patients diagnosed with MCI in the Neurology Department of the First Affiliated Hospital of Shandong Second Medical University from November 2023 to May 2024 were selected as the case group (MCI group). Cognitively normal (CN) volunteers, matched for age and education level and recruited from the physical examination center during the same period, served as the control group (CN group). The general demographic data of the study participants were collected. The Beijing versions of the Montreal Cognitive Assessment (MoCA), clinical dementia rating (CDR), and activities of daily living scale (ADL) were used to assess neuropsychological functions. Clinical periodontal examinations were conducted, the periodontal inflamed surface area (PISA) was calculated, and the periodontitis stage was determined in accordance with the 2018 classification. Fasting elbow venous blood samples were collected in the morning, and blood biochemical indicators were measured. Plasma p-tau217 levels were detected using enzyme-linked immunosorbent assay (ELISA). Statistical analyses were performed using t-test, Mann-Whitney U test, chi-square test, partial correlation analysis, multivariate Logistic regression analysis, multiple linear regression analysis, restricted cubic spline (RCS) regression analysis, and mediation effect analysis. RESULTS: Among the 192 participants, 96 belong to the MCI group and 96 to the CN group. The prevalence of periodontitis was 63.5% in the MCI group and 43.8% in the CN group, with a statistically significant difference (χ²=7.561, P=0.006). The plasma p-tau217 levels in the MCI group were significantly higher than those in the CN group [7.00 (4.27-9.65) ng/mL versus 2.02 (0.80-3.81) ng/mL, Z=-8.108, P<0.001]. Partial correlation analysis revealed that plasma p-tau217 levels were positively correlated with all the clinical periodontal indices (all P<0.001). After adjustments for baseline covariates, multivariate Logistic regression indicated that periodontitis was an independent risk factor for MCI. Patients with periodontitis had a 1.977-fold higher MCI risk than those without periodontitis (OR=1.977, 95%CI: 1.088-3.594, P=0.025). Moreover, the MCI risk for stage Ⅰ/Ⅱ periodontitis and stage Ⅲ/Ⅳ periodontitis was 1.878 times (OR=1.878, 95%CI: 1.029-3.425, P=0.040) and 2.625 times (OR=2.625, 95%CI: 1.073-6.246, P=0.035) higher than that for patients without periodontitis, respectively. Trend test showed that the MCI risk increased with periodontitis severity (P_trend=0.016). After adjustments for baseline covariates, multiple linear regression analysis showed that periodontitis was an independent risk factor for increased plasma p-tau217 levels (β=3.309, 95%CI: 2.363-4.254, P<0.001). Compared with patients without periodontitis, those with stage Ⅰ/Ⅱ periodontitis (β=1.838, 95%CI: 0.869-2.806, P<0.001) and stage Ⅲ/Ⅳ periodontitis (β=5.539, 95%CI: 4.442-6.636, P<0.001) had significantly higher plasma p-tau217 levels. In addition, trend test indicated that plasma p-tau217 levels increased with periodontitis severity (P_trend<0.001). After adjustments for baseline covariates, RCS regression analysis further revealed that PISA had a positive linear dose-response relationship with MCI risk (P_overall=0.002, P_nonlinear=0.344) and plasma p-tau217 levels (P_overall<0.001, P_nonlinear=0.140). After adjustments for baseline covariates, mediation analysis showed that plasma p-tau217 mediated the association between periodontitis and MCI, with a mediation proportion of 13.99% (95% Bootstrap CI: 0.38%-49.39%, P=0.038). CONCLUSIONS Periodontitis was independently positively associated with MCI risk, and plasma p-tau217 plays a mediating role in this association.
Humans ; Cognitive Dysfunction/complications* ; tau Proteins/blood* ; Periodontitis/complications* ; Case-Control Studies ; Male ; Female ; Phosphorylation ; Aged ; Middle Aged ; Activities of Daily Living

ObjectiveRapid eye movement sleep behavior disorder (RBD) is characterized by dream enactment and loss of muscle atonia during rapid eye movement sleep. RBD is closely related to α-synucleinopathies including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Many studies have investigated the markers of imaging and neurophysiological, genetic, cognitive, autonomic function of RBD and their predictive value for neurodegenerative diseases. This report reviewed the progress of these studies and discussed their limitations and future research directions.

Data SourcesUsing the combined keywords: "RBD", "neurodegenerative disease", "Parkinson disease", and "magnetic resonance imaging", the PubMed/MEDLINE literature search was conducted up to January 1, 2018.

Study SelectionA total of 150 published articles were initially identified citations. Of the 150 articles, 92 articles were selected after further detailed review. This study referred to all the important English literature in full.

ResultsSingle-nucleotide polymorphisms in SCARB2 (rs6812193) and MAPT (rs12185268) were significantly associated with RBD. The olfactory loss, autonomic dysfunction, marked electroencephalogram slowing during both wakefulness and rapid eye movement sleep, and cognitive impairments were potential predictive markers for RBD conversion to neurodegenerative diseases. Traditional structural imaging studies reported relatively inconsistent results, whereas reduced functional connectivity between the left putamen and substantia nigra and dopamine transporter uptake demonstrated by functional imaging techniques were relatively consistent findings.

ConclusionsMore longitudinal studies should be conducted to evaluate the predictive value of biomarkers of RBD. Moreover, because the glucose and dopamine metabolisms are not specific for assessing cognitive cognition, the molecular metabolism directly related to cognition should be investigated. There is a need for more treatment trials to determine the effectiveness of interventions of RBD on preventing the conversion to neurodegenerative diseases.

Biomarkers ; blood ; Humans ; Lysosome-Associated Membrane Glycoproteins ; genetics ; Neurodegenerative Diseases ; blood ; genetics ; physiopathology ; Parkinson Disease ; blood ; genetics ; physiopathology ; Polymorphism, Single Nucleotide ; genetics ; REM Sleep Behavior Disorder ; blood ; genetics ; physiopathology ; Receptors, Scavenger ; genetics ; tau Proteins ; genetics

OBJECTIVETo determine the changes of serum Tau protein, glial fibrillary acidic protein (GFAP), tumor necrosis factor alpha (TNF-α), and malonaldehyde (MDA) in rats after blast-related traumatic brain injury (BTBI) and to provide relative information for further studies on BTBI mechanism and seek specific biomarkers for BTBI.

METHODSNinety male Sprague-Dawley rats were randomly assigned into three groups: control group, moderate blast injury group, and severe blast injury group (n=30 for each). Rats in the moderate and severe blast injury groups were respectively exposed to corresponding levels of BTBI. After explosion, serum levels of Tau, GFAP, TNF-α, and MDA in each group were determined by Elisa assay at different time points after injury (8 h, 24 h, 3 d, and 6 d). The extent of brain damage was detected by Nissl staining and TUNEL assay.

RESULTSSerum levels of Tau and GFAP rapidly increased and reached the peak at 24 h after either moderate or severe blast injury. All the values were significantly higher than control group at all time points (P<0.05). Serum TNF-α level of both injury groups peaked at 8 h after BTBI and stayed significantly higher than control group at all time points (P<0.05). Serum MDA of two injury groups began to significantly increase at 3 d and the level stayed significantly higher than control group until 6 d (P<0.05). Moreover, unlike the other biomarkers, serum MDA of severe blast injury group was significantly higher than moderate blast injury group at 6 d (P<0.05).

CONCLUSIONThe changes of serum Tau, GFAP, and TNF-α showed a good sensitivity at the acute phase after BTBI (within 24 h). However, their specificity and correlation with the extent of injury were limited in this experiment. Moreover, although the change of serum MDA showed a poor sensitivity and specificity to the diagnosis of BTBI during the first few days, it can reflect the injury degree at 6 d after injury. Therefore, further studies are needed to improve the methods of detecting more serum markers and investigate the significance of multiple markers in diagnosing BTBI.

Animals ; Biomarkers ; blood ; Blast Injuries ; blood ; Brain Injuries ; blood ; Enzyme-Linked Immunosorbent Assay ; Glial Fibrillary Acidic Protein ; blood ; Male ; Malondialdehyde ; blood ; Rats ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha ; analysis ; tau Proteins ; blood

Alzheimer's disease (AD), also called presenile dementia, is one of the most common neurodegenerative diseases in elderly people. The main pathological features of AD include senile plaques (SPs), neurofibrillary tangles (NFTs) and neuron loss. A biomarker is a characteristic that can be objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacological responses to a therapeutic intervention. Class biomarkers of AD such as Abeta and phosphorylated tau have been widely used in clinical diagnosis of AD patients. Recently, novel technologies like proteomics, genomics, and imaging techniques have expanded the role of a biomarker from early diagnosis to monitoring the progression of diseases and evaluating the response to various treatments. In this article, we will review the progress of various biomarkers of AD.
Adipokines ; cerebrospinal fluid ; Alzheimer Disease ; cerebrospinal fluid ; diagnosis ; diagnostic imaging ; metabolism ; Amyloid beta-Peptides ; cerebrospinal fluid ; Biomarkers ; analysis ; Chitinase-3-Like Protein 1 ; Fluorodeoxyglucose F18 ; Humans ; Lectins ; cerebrospinal fluid ; Peptide Fragments ; cerebrospinal fluid ; Phosphorylation ; Positron-Emission Tomography ; Presenilins ; analysis ; alpha 1-Antitrypsin ; blood ; tau Proteins ; cerebrospinal fluid

Alzheimer's disease (AD) is currently diagnosed only via clinical assessments and confirmed by postmortem brain pathology. Biochemical and neuroimaging markers could facilitate diagnosis, predict AD progression from a pre-AD state of mild cognitive impairment (MCI), and be used to monitor efficacies of disease-modifying therapies. It is now clear that cerebrospinal fluid (CSF) levels of A beta 40, A beta 42, total tau and phosphorylated tau have diagnostic values in AD. Measurements of the above CSF markers in combination are useful in predicting the risk of progression from MCI to AD. Recent advances further support a notion that plasma A beta levels, expressed as an A beta 42/A beta 40 ratio, could also be of value. New potential biomarkers are emerging, and CSF or plasma marker profiles may eventually become part of the clinician's toolkit for accurate AD diagnosis and management. These biomarkers, along with clinical assessment, neuropsychological testing and neuroimaging could achieve a much higher diagnostic accuracy for AD and related disorders in the future.
Alzheimer Disease ; blood ; cerebrospinal fluid ; Amyloid beta-Peptides ; blood ; cerebrospinal fluid ; Biomarkers ; blood ; cerebrospinal fluid ; Cognition Disorders ; blood ; cerebrospinal fluid ; Humans ; tau Proteins ; blood ; cerebrospinal fluid

OBJECTIVETo investigate effect of inhibiting melatonin biosynthesis on activities of protein kinase A (PKA), glycogen synthase kinase-3 (GSK-3) and tau phosphorylation at PS214 and M4 epitopes using haloperidol, a specific inhibitor of 5-hydroxyindole-O-methyltransferase.

METHODSBrain ventricular and intraperitoneal injections were used for haloperidol administration, Western blots for tau phosphorylation, 32P-labeling for PKA and GSK-3 activity, and high performance liquid chromatograph for detection of serum melatonin levels.

RESULTSHaloperidol injection through the lateral ventricle and intraperitoneal reinforcement significantly stimulated PKA activity with a concurrent hyperphosphorylation of tau at M4 (Thr231/Ser235) and PS214 (Ser214) sites. Prior treatment of the rats using melatonin supplement for one week and reinforcement during the haloperidol administration arrested PKA activity and attenuated tau hyperphosphorylation. GSK-3 activity showed no obvious change after haloperidol injection, however, melatonin supplements and reinforcements during haloperidol infusion inactivated basal activity of GSK-3.

CONCLUSIONDecreased melatonin may be involved in Alzheimer-like tau hyperphosphorylation, and overactivation of PKA may play a crucial role in this process.

Animals ; Cyclic AMP-Dependent Protein Kinases ; metabolism ; Epitopes ; Glycogen Synthase Kinase 3 ; metabolism ; Haloperidol ; administration & dosage ; pharmacology ; Hippocampus ; enzymology ; metabolism ; Injections, Intraperitoneal ; Injections, Intraventricular ; Male ; Melatonin ; biosynthesis ; blood ; Phosphorylation ; drug effects ; Rats ; Rats, Wistar ; tau Proteins ; metabolism