Changes of NLRP3 in serum and cerebrospinal fluid of patients after moderate to severe traumatic brain injury and their predictive values for prognosis.

BACKGROUND: Traumatic brain injury (TBI) remains a major concern for global health. Recent studies have suggested the role of NOD-like receptor pyrin domain-containing protein 3 (NLRP3), an inflammatory marker, in the cerebrospinal fluid (CSF) and serum as potential indicators of TBI prognosis. The objective of the study was to characterize NLRP3 as a clinically applicable tool for predicting the outcomes of TBI patients. METHODS: A total of 270 patients with moderate to severe TBI were included in this retrospective analysis. Serum and CSF samples were collected at 1-, 3-, 7-, and 21-day post-injury to measure NLRP3 levels. The prognosis of patients was evaluated after 3 months using the Glasgow Outcome Scale (GOS). Patients were categorized into good prognosis (GOS score >3) and poor prognosis (GOS score ≤3) groups. The relationship between NLRP3 levels and prognosis was analyzed. RESULTS: Patients with poor prognosis had significantly elevated NLRP3 levels in their serum on days 1 and 3 post-injury compared with those with a good prognosis. The difference was more pronounced during these early days compared with days 7 and 21. However, NLRP3 levels in CSF consistently showed a large difference between the two groups throughout the observation period. Receiver operating characteristic analysis revealed that the level of NLRP3 in the CSF on day 3 post-injury had the highest predictive value for prognosis, with an area under the curve of 0.83, followed by the level of NLRP3 in the serum on day 3 post-injury. CONCLUSIONS: The levels of NLRP3, especially in the CSF on day 3 post-injury, can serve as a potential biomarker for predicting prognosis in moderate to severe TBI patients. Early measurement of NLRP3 levels can provide valuable insights into patient outcomes and guide therapeutic strategies.

Elevated cerebrospinal fluid galectin-3 and associated cytokines after severe traumatic brain injury in patients.

This study aimed to investigate the galectin-3 and associated cytokines levels in the cerebrospinal fluid (CSF) of severe traumatic brain injury (sTBI) patients. Temporal CSF expression of galectin-3 and associated cytokines levels in sTBI patients within 1-week post-injury were studied using the multiplex bead array. STBI patient group was stratified using the Modified Rankin Score (mRS) into 3 groups: mRS 6 (died), mRS 5 (severely disabled) and mRS 1-4 (mild-to-moderately disabled) group. Analysis for bead array data using Kruskal-Wallis test with post hoc Dunn's multiple comparisons test, and temporal changes and correlation analysis using Spearman's correlation were carried out. At day 1 post-injury, CSF galectin-3 and interleukin-6 (IL-6), interleukin-10 (IL-10), cysteine-cysteine motif chemokine ligand-2 (CCL-2), and cysteine-cysteine motif chemokine ligand-20 (CCL-20), but not interleukin-1ß (IL-1ß) and tumor necrosis factor (TNF-α) levels were significantly elevated in mRS 5 group compared to non-TBI controls. Temporal correlation analysis at 1-7 days showed decreased IL-10 level in the mRS 6 group, decreased IL-10 and CCL-2 levels in mRS 5 group, and decreased IL-6, CCL-2, and CCL-20 levels in the mRS 1-4 group. Receiver operating characteristic curve analyses revealed a significant area under the curve for comparison between mRS 6 and mRS 5 groups for galectin-3 and IL-6. No significant differences in sex, age, Glasgow Coma Scale score, C-reactive protein levels and types of TBI-induced hemorrhages were observed between the groups. CSF galectin-3 and associated cytokines, especially IL-6, CCL-2 and CCL-20 levels were different within sub-groups of sTBI patients, suggesting their potential use in sTBI prognostics.

Higher Cerebrospinal Fluid Levels of Amyloid-ß40 Following Traumatic Brain Injury Relate to Confrontation Naming Performance.

Background: Traumatic brain injury (TBI) may confer risk for Alzheimer's disease (AD) through amyloid-ß (Aß) overproduction. However, the relationship between TBI and Aß levels in cerebrospinal fluid (CSF) remains unclear. Objective: To explore whether Aß overproduction is implicated in the relationship between TBI and AD, we compared CSF levels of Aß in individuals with a TBI history versus controls (CTRLs) and related CSF Aß levels to cognitive markers associated with preclinical AD. Methods: Participants were 112 non-impaired Veterans (TBI = 56, CTRL = 56) from the Alzheimer's Disease Neuroimaging Initiative-Department of Defense database with available cognitive data (Boston Naming Test [BNT], Rey Auditory Verbal Learning Test [AVLT]) and CSF measures of Aß42, Aß40, and Aß38. Mediation models explored relationships between TBI history and BNT scores with Aß peptides as mediators. Results: The TBI group had higher CSF Aß40 (t = -2.43, p = 0.017) and Aß38 (t = -2.10, p = 0.038) levels than the CTRL group, but groups did not differ in CSF Aß42 levels or Aß42/Aß40 ratios (p > 0.05). Both Aß peptides negatively correlated with BNT (Aß40: rho = -0.20, p = 0.032; Aß38: rho = -0.19, p = 0.048) but not AVLT (p > 0.05). Aß40 had a significant indirect effect on the relationship between TBI and BNT performance (ß= -0.16, 95% CI [-0.393, -0.004], PM = 0.54). Conclusions: TBI may increase AD risk and cognitive vulnerability through Aß overproduction. Biomarker models incorporating multiple Aß peptides may help identify AD risk among those with TBI.

Cerebrospinal fluid biomarkers and cognitive trajectories in patients with Alzheimer's disease and a history of traumatic brain injury.

Traumatic brain injury (TBI) and Alzheimer's disease (AD) have overlapping mechanisms but it remains unknown if pathophysiological characteristics and cognitive trajectories in AD patients are influenced by TBI history. Here, we studied AD patients (stage MCI or dementia) with TBI history (ADTBI+, n=110), or without (ADTBI-, n=110) and compared baseline CSF concentrations of amyloid beta 1-42 (Aß42), phosphorylated tau181 (pTau181), total tau, neurofilament light chain (NfL), synaptosomal associated protein-25kDa (SNAP25), neurogranin (Ng), neuronal pentraxin-2 (NPTX2) and glutamate receptor-4 (GluR4), as well as differences in cognitive trajectories using linear mixed models. Explorative, analyses were repeated within stratified TBI groups by TBI characteristics (timing, severity, number). We found no differences in baseline CSF biomarker concentrations nor in cognitive trajectories between ADTBI+ and ADTBI- patients. TBI >5 years ago was associated with higher NPTX2 and a tendency for higher SNAP25 concentrations compared to TBI ≤ 5 years ago, suggesting that TBI may be associated with long-term synaptic dysfunction only when occurring before onset or in a pre-clinical disease stage of AD.

Neuroforensomics: metabolites as valuable biomarkers in cerebrospinal fluid of lethal traumatic brain injuries.

Traumatic brain injury (TBI) is a ubiquitous, common sequela of accidents with an annual prevalence of several million cases worldwide. In forensic pathology, structural proteins of the cellular compartments of the CNS in serum and cerebrospinal fluid (CSF) have been predominantly used so far as markers of an acute trauma reaction for the biochemical assessment of neuropathological changes after TBI. The analysis of endogenous metabolites offers an innovative approach that has not yet been considered widely in the assessment of causes and circumstances of death, for example after TBI. The present study, therefore, addresses the question whether the detection of metabolites by liquid-chromatography-mass spectrometry (LC/MS) analysis in post mortem CSF is suitable to identify TBI and to distinguish it from acute cardiovascular control fatalities (CVF). Metabolite analysis of 60 CSF samples collected during autopsies was performed using high resolution (HR)-LC/MS. Subsequent statistical and graphical evaluation as well as the calculation of a TBI/CVF quotient yielded promising results: numerous metabolites were identified that showed significant concentration differences in the post mortem CSF for lethal acute TBI (survival times up to 90 min) compared to CVF. For the first time, this forensic study provides an evaluation of a new generation of biomarkers for diagnosing TBI in the differentiation to other causes of death, here CVF, as surrogate markers for the post mortem assessment of complex neuropathological processes in the CNS ("neuroforensomics").

Parallel Cerebrospinal Fluid and Serum Temporal Profile Assessment of Axonal Injury Biomarkers Neurofilament-Light Chain and Phosphorylated Neurofilament-Heavy Chain: Associations With Patient Outcome in Moderate-Severe Traumatic Brain Injury.

Neurofilament-light chain (NF-L) and phosphorylated neurofilament-heavy chain (pNF-H) are axonal proteins that have been reported as potential diagnostic and prognostic biomarkers in traumatic brain injury (TBI). However, detailed temporal profiles for these proteins in blood, and interrelationships in the acute and chronic time periods post-TBI have not been established. Our objectives were: 1) to characterize acute-to-chronic serum NF-L and pNF-H profiles after moderate-severe TBI, as well as acute cerebrospinal fluid (CSF) levels; 2) to evaluate CSF and serum NF-L and pNF-H associations with each other; and 3) to assess biomarker associations with global patient outcome using both the Glasgow Outcome Scale-Extended (GOS-E) and Disability Rating Scale (DRS). In this multi-cohort study, we measured serum and CSF NF-L and pNF-H levels in samples collected from two clinical cohorts (University of Pittsburgh [UPITT] and Baylor College of Medicine [BCM]) of individuals with moderate-severe TBI. The UPITT cohort includes 279 subjects from an observational cohort study; we obtained serum (n = 277 unique subjects) and CSF (n = 95 unique subjects) daily for 1 week, and serum every 2 weeks for 6 months. The BCM cohort included 103 subjects from a previous randomized clinical trial of erythropoietin and blood transfusion threshold after severe TBI, which showed no effect on neurological outcome between treatment arms; serum (n = 99 unique subjects) and CSF (n = 54 unique subjects) NF-L and pNF-H levels were measured at least daily during Days (D) 0-10 post-injury. GOS-E and DRS were assessed at 6 months (both cohorts) and 12 months (UPITT cohort only). Results show serum NF-L and pNF-H gradually rise during the first 10 days and peak at D20-30 post-injury. In the UPITT cohort, acute (D0-6) NF-L and pNF-H levels correlate within CSF and serum (Spearman r = 0.44-0.48; p < 0.05). In the UPITT cohort, acute NF-L CSF and serum levels, as well as chronic (Months [M]2-6) serum NF-L levels, were higher among individuals with unfavorable GOS-E and worse DRS at 12 months (p < 0.05, all comparisons). In the BCM cohort, higher acute serum NF-L levels were also associated with unfavorable GOS-E. Higher pNF-H serum concentrations (D0-6 and M2-6), but not CSF pNF-H, were associated with unfavorable GOS-E and worse DRS (p < 0.05, all comparisons) in the UPITT cohort. Relationships between biomarker levels and favorable outcome persisted after controlling for age, sex, and Glasgow Coma Scale. This study shows for the first time that serum levels of NF-L and pNF-H peak at D20-30 post-TBI. Serum NF-L levels, and to a lesser extent pNF-H levels, are robustly associated with global patient outcomes and disability after moderate-severe TBI. Further studies on clinical utility as prognosis and treatment-response indicators are needed.

Dynamic Changes and Effects of H2S, IGF-1, and GH in the Traumatic Brain Injury.

The aim of this study was to examine the expression changes of H2S, IGF-1, and GH in traumatic brain injury (TBI) patients and to detect their neuroprotective functions after TBI. In this study, we first collected cerebrospinal fluid (CSF) and plasma from TBI patients at different times after injury and evaluated the concentrations of H2S, IGF-1, and GH. In vitro studies were using the scratch-induced injury model and cell-cell interaction model (HT22 hippocampal neurons co-cultured with LPS-induced BV2 microglia cells). In vivo studies were using the controlled cortical impact (CCI) model in mice. Cell viability was assessed by CCK-8 assay. Pro-inflammatory cytokines expression was determined by qRT-PCR, ELISA, and nitric oxide production. Western blot was performed to assess the expression of CBS, CSE, IGF-1, and GHRH. Moreover, the recovery of TBI mice was evaluated for behavioral function by applying the modified Neurological Severity Score (mNSS), the Rotarod test, and the Morris water maze. We discovered that serum H2S, CSF H2S, and serum IGF-1 concentrations were all adversely associated with the severity of the TBI, while the concentrations of IGF-1 and GH in CSF and GH in the serum were all positively related to TBI severity. Experiments in vitro and in vivo indicated that treatment with NaHS (H2S donor), IGF-1, and MR-409 (GHRH agonist) showed protective effects after TBI. This study gives novel information on the functions of H2S, IGF-1, and GH in TBI.

Real-Time PCR Quantification of 87 miRNAs from Cerebrospinal Fluid: miRNA Dynamics and Association with Extracellular Vesicles after Severe Traumatic Brain Injury.

Severe traumatic brain injury (sTBI) is an intracranial damage triggered by external force, most commonly due to falls and traffic accidents. The initial brain injury can progress into a secondary injury involving numerous pathophysiological processes. The resulting sTBI dynamics makes the treatment challenging and prompts the improved understanding of underlying intracranial processes. Here, we analysed how extracellular microRNAs (miRNAs) are affected by sTBI. We collected thirty-five cerebrospinal fluids (CSF) from five sTBI patients during twelve days (d) after the injury and combined them into d1-2, d3-4, d5-6 and d7-12 CSF pools. After miRNA isolation and cDNA synthesis with added quantification spike-ins, we applied a real-time PCR-array targeting 87 miRNAs. We detected all of the targeted miRNAs, with totals ranging from several nanograms to less than a femtogram, with the highest levels found at d1-2 followed by decreasing levels in later CSF pools. The most abundant miRNAs were miR-451a, miR-16-5p, miR-144-3p, miR-20a-5p, let-7b-5p, miR-15a-5p, and miR-21-5p. After separating CSF by size-exclusion chromatography, most miRNAs were associated with free proteins, while miR-142-3p, miR-204-5p, and miR-223-3p were identified as the cargo of CD81-enriched extracellular vesicles, as characterised by immunodetection and tunable resistive pulse sensing. Our results indicate that miRNAs might be informative about both brain tissue damage and recovery after sTBI.

Transient post-operative overexpression of CXCR2 on monocytes of traumatic brain injury patients drives monocyte chemotaxis toward cerebrospinal fluid and enhances monocyte-mediated immunogenic cell death of neurons in vitro.

BACKGROUND: After traumatic brain injury (TBI), peripheral monocytes infiltrate into the central nervous system due to disruption of the blood-brain barrier, and play an important role in neuroinflammation. However, the mechanisms regulating the movement and function of peripheral monocytes after TBI have not been fully investigated. METHODS: TBI patients who underwent surgery at our hospital were recruited. CXCR2 expression in CD14+ monocytes from peripheral blood and cerebrospinal fluid (CSF) of TBI patients around surgery was analyzed by flow cytometry and compared with that of patients who suffered TBI 2-24 months prior and underwent cranioplasty. In vitro, serum or CSF from TBI/non-TBI patients were used to treat peripheral monocytes isolated from healthy volunteers to evaluate their effect on CXCR2 expression. Transwell experiments were performed to analyze the role of CXCR2 in monocyte chemotaxis toward the CSF. The role of CXCR2 in monocyte-mediated immunogenic cell death (ICD) of nerve cells was explored in an indirect co-culture system. RESULTS: Transient CXCR2 upregulation in monocytes from the peripheral blood and CSF of TBI patients was detected soon after surgery and was associated with unfavorable outcomes. TBI serum and CSF promoted CXCR2 expression in monocytes, and dexamethasone reversed this effect. Peripheral monocytes from TBI patients showed enhanced chemotaxis toward the CSF and increased inflammatory cytokine secretion. The CXCR2 antagonist SB225002 decreased monocyte chemotaxis toward TBI CSF, and lowered pro-inflammatory cytokine secretion in monocytes treated with TBI serum. SB225002 also relieved ICD in nerve cells co-cultured with TBI serum-treated monocytes. CONCLUSIONS: CXCR2 is transiently overexpressed in the peripheral monocytes of TBI patients post-surgery, and drives peripheral monocyte chemotaxis toward CSF and monocyte-mediated ICD of nerve cells. Therefore, CXCR2 may be a target for monocyte-based therapies for TBI.

Pathogenic cis p-tau levels in CSF reflects severity of traumatic brain injury.

Traumatic brain injury (TBI) is the main cause of death and disability among young people. Following TBI, immune system activation and cytokine release induce kinase activity and hyperphosphorylation of tau protein, a structural molecule in axonal microtubules. The cis configuration of phosphorylated tau at Th231 is extremely neurotoxic and is having a prion nature, spreads to brain areas as well as CSF.We examined the cerebrospinal fluid (CSF) cis p-tau levels in 32 TBI patients and 5 non-TBI controls to find out the correlation with TBI severity.   CSF samples were drained 5-7 days after TBI and subjected for ELISA analysis with anti cis p-tau and ß-amyloid antibodies.We had no patients with mild TBI, two patients with moderate (6.2%), 23 patients with severe (71.9%), and 7 patients with critical TBI (21.9%). While mean CSF ß-amyloid in TBI and control groups did not show a statistically significant difference, the mean CSF cis p-tau level was significantly higher in the TBI group than the control samples. Also, intergroup analysis demonstrated that CSF cis p-tau levels were statistically different according to the head injury severity.Although CSF cis p-tau increased in the TBI patients, ß-amyloid did not show a significant difference between patients and controls. Also, we observed an obvious negative correlation between CSF cis p-tau levels and GCS scores. Therefore, future researches on suppression of cis P-tau production or removing previously produced cis P-tau could be a suitable approach in treating TBI in order to prevent tauopathies and future neurodegeneration.

Generation and Release of Neurogranin, Vimentin, and MBP Proteolytic Peptides, Following Traumatic Brain Injury.

Traumatic brain injury (TBI) is a major neurological disorder without FDA-approved therapies. In this study, we have examined the concept that TBI might trigger global brain proteolysis in the acute post-injury phase. Thus, we conducted a systemic proteolytic peptidomics analysis using acute cerebrospinal fluid (CSF) samples from TBI patients and normal control samples. We employed ultrafiltration-based low molecular weight (LMW; < 10 kDa) peptide enrichment, coupled with nano-reversed-phase liquid chromatography/tandem mass spectrometry analysis, followed with orthogonal quantitative immunoblotting-based protein degradation analysis. We indeed identified novel patterns of injury-dependent proteolytic peptides derived from neuronal components (pre- and post-synaptic terminal, dendrites, axons), extracellular matrix, oligodendrocytes, microglial cells, and astrocytes. Among these, post-synaptic protein neurogranin was identified for the first time converted to neurogranin peptides including neurogranin peptide (aa 16-64) that is phosphorylated at Ser-36/48 (P-NG-fragment) in acute human TBI CSF samples vs. normal control with a receiver operating characteristic area under the curve of 0.957. We also identified detailed processing of astroglia protein (vimentin) and oligodendrocyte protein (MBP and Golli-MBP) to protein breakdown products (BDPs) and/or LMW proteolytic peptides after TBI. In addition, using MS/MS selected reaction monitoring method, two C-terminally released MBP peptides TQDENPVVHFF and TQDENPVVHF were found to be elevated in acute and subacute TBI CSF samples as compared to their normal control counterparts. These findings imply that future therapeutic strategies might be placed on the suppression of brain proteolysis as a target. The endogenous proteolytic peptides discovered in human TBI biofluid could represent useful diagnostic and monitoring tools for TBI.

Characterization and standardization of multiassay platforms for four commonly studied traumatic brain injury protein biomarkers: a TBI Endpoints Development Study.

Aim: There is a critical need to validate biofluid-based biomarkers as diagnostic and drug development tools for traumatic brain injury (TBI). As part of the TBI Endpoints Development Initiative, we identified four potentially predictive and pharmacodynamic biomarkers for TBI: astroglial markers GFAP and S100B and the neuronal markers UCH-L1 and Tau. Materials & methods: Several commonly used platforms for these four biomarkers were identified and compared on analytic performance and ability to detect gold standard recombinant protein antigens and to pool control versus TBI cerebrospinal fluid (CSF). Results: For each marker, only some assay formats could differentiate TBI CSF from the control CSF. Also, different assays for the same biomarker reported divergent biomarker values for the same biosamples. Conclusion: Due to the variability of TBI marker assay in performance and reported values, standardization strategies are recommended when comparing reported biomarker levels across assay platforms.

Lay abstract Traumatic brain injury (TBI) is a leading cause of mortality and morbidity around the world. There is a critical need to validate biofluid-based biomarker tests as diagnostic and drug development tools. For this study, we focused on four brain-derived proteins called GFAP, S100B, UCH-L1 and Tau. To measure these biomarker proteins in human biofluid, one relies on either commercial or home-brew assays. Here, we attempted to compare the performance of 2­4 assay formats for each biomarker. We compared their assay sensitivity, ability to detect 'gold standard' protein analyte we procured, as well as the ability to differentiated pooled TBI cerebrospinal fluid from healthy control cerebrospinal fluid. We found that there are high variabilities among TBI marker assays in assay performance, reported biomarker values and ability to differentiate TBI versus control biofluid. Thus, a standardization strategy is needed when comparing reported biomarker levels across assay platforms.

Screening for Fatal Traumatic Brain Injuries in Cerebrospinal Fluid Using Blood-Validated CK and CK-MB Immunoassays.

A single, specific, sensitive biochemical biomarker that can reliably diagnose a traumatic brain injury (TBI) has not yet been found, but combining different biomarkers would be the most promising approach in clinical and postmortem settings. In addition, identifying new biomarkers and developing laboratory tests can be time-consuming and economically challenging. As such, it would be efficient to use established clinical diagnostic assays for postmortem biochemistry. In this study, postmortem cerebrospinal fluid samples from 45 lethal TBI cases and 47 controls were analyzed using commercially available blood-validated assays for creatine kinase (CK) activity and its heart-type isoenzyme (CK-MB). TBI cases with a survival time of up to two hours showed an increase in both CK and CK-MB with moderate (CK-MB: AUC = 0.788, p < 0.001) to high (CK: AUC = 0.811, p < 0.001) diagnostic accuracy. This reflected the excessive increase of the brain-type CK isoenzyme (CK-BB) following a TBI. The results provide evidence that CK immunoassays can be used as an adjunct quantitative test aid in diagnosing acute TBI-related fatalities.

Phosphorylated Neurofilament Heavy Chain in the Cerebrospinal Fluid Is a Suitable Biomarker of Acute and Chronic Blast-Induced Traumatic Brain Injury.

Blast-induced traumatic brain injury (bTBI) has been documented as a significant concern for both military and civilian populations in response to the increased use of improvised explosive devices. Identifying biomarkers that could aid in the proper diagnosis and assessment of both acute and chronic bTBI is in urgent need since little progress has been made towards this goal. Addressing this knowledge gap is especially important in military veterans who are receiving assessment and care often years after their last blast exposure. Neuron-specific phosphorylated neurofilament heavy chain protein (pNFH) has been successfully evaluated as a reliable biomarker of different neurological disorders, as well as brain trauma resulting from contact sports and acute stages of brain injury of different origin. In the present study, we have evaluated the utility of pNFH levels measured in the cerebrospinal fluid (CSF) as an acute and chronic biomarker of brain injury resulting from single and tightly coupled repeated blast exposures using experimental rats. The pNFH levels increased at 24 h, returned to normal levels at 1 month, but increased again at 6 months and 1 year post-blast exposures. No significant changes were observed between single and repeated blast-exposed groups. To determine whether the observed increase of pNFH in CSF corresponded with its levels in the brain, we performed fluorescence immunohistochemistry in different brain regions at the four time-points evaluated. We observed decreased pNFH levels in those brain areas at 24 h, 6 months, and 1 year. The results suggest that blast exposure causes axonal degeneration at acute and chronic stages resulting in the release of pNFH, the abundant neuronal cytoskeletal protein. Moreover, the changes in pNFH levels in the CSF negatively correlated with the neurobehavioral functions in the rats, reinforcing suggestions that CSF levels of pNFH can be a suitable biomarker of bTBI.

BNP and NT-proBNP Concentrations in Paired cerebrospinal Fluid and Plasma Samples of Patients with Traumatic Brain Injury.

BACKGROUND: The aim of this study was to investigate the secretion patterns of brain natriuretic peptide (BNP) and N-terminal-proBNP (NT-proBNP) after traumatic brain injury (TBI) and to analyze the source of them in cerebrospinal fluid (CSF). MATERIALS AND METHODS: We synchronously measured BNP and NT-proBNP concentrations in paired CSF and plasma samples from 22 moderate to severe TBI patients and 40 healthy control patients. The CSF and/or plasma ratio of albumin (QAlbumin) was calculated daily. The BNP and NT-proBNP levels of CSF and plasma were compared between TBI patients and control patients. RESULTS: CSF BNP and NT-proBNP levels peaked on day 3 after injury, as did the plasma BNP and NT-proBNP levels. The CSF BNP and NT-proBNP levels in TBI patients were elevated from day 1, which was significantly higher than control group (P < 0.05 and P < 0.01, respectively). However, in plasma, only NT-proBNP levels were significantly higher than in the control group from day 2 (P < 0.05). In addition, QBNP, defined as CSF BNP concentration and/or plasma BNP concentration, was significantly higher in TBI patients than in the control group (P < 0.01). However, QAlbumin remained within ranges of a mild to moderate dysfunction of blood-brain-barrier in TBI patients. CONCLUSIONS: CSF BNP concentrations are elevated and peak on day 3 after moderate to severe TBI. CSF BNP may originate from the brain and may be a potential biomarker of TBI.

Acute Brain-Derived Neurotrophic Factor DNA Methylation Trajectories in Cerebrospinal Fluid and Associations With Outcomes Following Severe Traumatic Brain Injury in Adults.

Background. Epigenetic biomarkers have the potential to explain outcome heterogeneity following traumatic brain injury (TBI) but are largely unexplored. Objective. This exploratory pilot study characterized brain-derived neurotrophic factor (BDNF) DNA methylation trajectories following severe TBI. Methods. Brain-derived neurotrophic factor DNA methylation trajectories in cerebrospinal fluid (CSF) over the first 5 days following severe TBI in 112 adults were examined in association with 3- and 12-month outcomes. Results. Group-based trajectory analysis revealed low and high DNA methylation groups at two BDNF cytosine-phosphate-guanine (CpG) targets that showed suggestive associations (P < .05) with outcomes. Membership in the high DNA methylation groups was associated with better outcomes after controlling for age, sex, and injury severity. Associations of age × trajectory group interactions with outcomes at a third CpG site revealed a pattern of the same or better outcomes with higher ages in the high DNA methylation group and worse outcomes with higher ages in the low DNA methylation group. Conclusions. Although no observed associations met the empirical significance threshold after correcting for multiple comparisons, suggestive associations of the main effect models were consistent in their direction of effect and were observed across two CpG sites and two outcome time points. Results suggest that higher acute CSF BDNF DNA methylation may promote recovery following severe TBI in adults, and this effect may be more robust with higher age. While the results require replication in larger and racially diverse independent samples, BDNF DNA methylation may serve as an early postinjury biomarker helping to explain outcome heterogeneity following TBI.

AMPK induces regulatory innate lymphoid cells after traumatic brain injury.

The CNS is regarded as an immunoprivileged organ, evading routine immune surveillance; however, the coordinated development of immune responses profoundly influences outcomes after brain injury. Innate lymphoid cells (ILCs) are cytokine-producing cells that are critical for the initiation, modulation, and resolution of inflammation, but the functional relevance and mechanistic regulation of ILCs are unexplored after acute brain injury. We demonstrate increased proliferation of all ILC subtypes within the meninges for up to 1 year after experimental traumatic brain injury (TBI) while ILCs were present within resected dura and elevated within cerebrospinal fluid (CSF) of moderate-to-severe TBI patients. In line with energetic derangements after TBI, inhibition of the metabolic regulator, AMPK, increased meningeal ILC expansion, whereas AMPK activation suppressed proinflammatory ILC1/ILC3 and increased the frequency of IL-10-expressing ILC2 after TBI. Moreover, intracisternal administration of IL-33 activated AMPK, expanded ILC2, and suppressed ILC1 and ILC3 within the meninges of WT and Rag1-/- mice, but not Rag1-/- IL2rg-/- mice. Taken together, we identify AMPK as a brake on the expansion of proinflammatory, CNS-resident ILCs after brain injury. These findings establish a mechanistic framework whereby immunometabolic modulation of ILCs may direct the specificity, timing, and magnitude of cerebral immunity.

Lipid profiling of brain tissue and blood after traumatic brain injury: A review of human and experimental studies.

Traumatic brain injury (TBI) is a neurological condition which affects a large number of individuals worldwide, across all ages. It can lead to major physical, cognitive and psychological impairment, and represents a considerable health cost burden. TBI is a heterogeneous condition and there has been intense effort over the last decade to identify better biomarkers, which would enable an optimum and personalized treatment. The brain is highly enriched in a variety of lipids, including fatty acids, glycerophospholipids, glycerolipids, sterols and sphingolipids. There is accumulating evidence in clinical studies in TBI patients and also in experimental models of TBI, that injury triggers a complex pattern of changes in various lipid classes. Such changes can be detected in blood (plasma/serum), cerebrospinal fluid and also in brain tissue. They provide new insights into the pathophysiology of TBI, and have biomarker potential. Here, we review the various changes reported and discuss the scope and value of these lipid focused studies within the TBI field.

Cerebrospinal fluid brevican and neurocan fragment patterns in human traumatic brain injury.

BACKGROUND: Altered levels of two extracellular matrix (ECM) proteoglycans, brevican and neurocan, have been found in brain injury models; however, their proteolytic processing in traumatic brain injury (TBI) remains unexplored. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) is a possible contributor to ECM remodelling following TBI. The aims of this study were to evaluate proteolytic brevican/neurocan patterns and ADAMTS-like activity in cerebrospinal fluid (CSF) in the context of TBI. MATERIALS AND METHODS: Forty-two acute TBI patients and 37 idiopathic normal pressure hydrocephalus (iNPH) patients were included in the analysis of tryptic brevican and neurocan peptides in CSF using parallel reaction monitoring mass spectrometry. Twenty-nine TBI and 36 iNPH patients were analysed for ADAMTS-like activity in CSF using a quenched fluorescent substrate. RESULTS: The majority of CSF concentrations of brevican peptides significantly decreased in TBI patients compared with the iNPH group (p ≤ 0.002), while ADAMTS-like activity increased (p < 0.0001). Two C-terminal brevican peptides strongly correlated with unfavourable outcome of TBI patients (rho = 0.85-0.93, p ≤ 0.001). CONCLUSIONS: The decreased CSF concentrations of brevican peptides in TBI are associated with their increased degradation by ADAMTS enzymes. Furthermore, the N- and C-terminal parts of brevican are differentially regulated following TBI and may serve as outcome markers.

Dynamics of cerebrospinal fluid levels of matrix metalloproteinases in human traumatic brain injury.

Matrix metalloproteinases (MMPs) are extracellular enzymes involved in the degradation of extracellular matrix (ECM) proteins. Increased expression of MMPs have been described in traumatic brain injury (TBI) and may contribute to additional tissue injury and blood-brain barrier damage. The objectives of this study were to determine longitudinal changes in cerebrospinal fluid (CSF) concentrations of MMPs after acute TBI and in relation to clinical outcomes, with patients with idiopathic normal pressure hydrocephalus (iNPH) serving as a contrast group. The study included 33 TBI patients with ventricular CSF serially sampled, and 38 iNPH patients in the contrast group. Magnetic bead-based immunoassays were utilized to measure the concentrations of eight MMPs in ventricular human CSF. CSF concentrations of MMP-1, MMP-3 and MMP-10 were increased in TBI patients (at baseline) compared with the iNPH group (p < 0.001), while MMP-2, MMP-9 and MMP-12 did not differ between the groups. MMP-1, MMP-3 and MMP-10 concentrations decreased with time after trauma (p = 0.001-0.04). Increased concentrations of MMP-2 and MMP-10 in CSF at baseline were associated with an unfavourable TBI outcome (p = 0.002-0.02). Observed variable pattern of changes in MMP concentrations indicates that specific MMPs serve different roles in the pathophysiology following TBI, and are in turn associated with clinical outcomes.