Early IL-6 plasma concentrations correlate with severity of brain injury and pneumonia in brain-injured patients

Diffusion tensor imaging and plasma immunological biomarker panel in a rat traumatic brain injury (TBI) model and in human clinical TBI

Introduction

Neuroinflammatory reactions play a significant role in the pathology and long-term consequences of traumatic brain injury (TBI) and may mediate salutogenic processes that white matter integrity. This study aimed to investigate the relationship between inflammatory markers and white matter integrity following TBI in both a rat TBI model and clinical TBI cases.

Methods

In the rat model, blood samples were collected following a controlled cortical impact (CCI) to assess a panel of inflammatory markers; MR-based diffusion tensor imaging (DTI) was employed to evaluate white matter integrity 60 days post-injury. 15 clinical TBI patients were similarly assessed for a panel of inflammatory markers and DTI post-intensive care unit discharge. Blood samples from healthy controls were used for comparison of the inflammatory markers.

Results

Time-dependent elevations in immunological markers were observed in TBI rats, with a correlation to preserved fractional anisotropy (FA) in white matter. Specifically, TBI-induced increased plasma levels of IL-1β, IL-6, G-CSF, CCL3, CCL5, and TNF-α were associated with higher white matter integrity, as measured by FA. Clinical cases had similar findings: elevated inflammatory markers (relative to controls) were associated with preservation of FA in vulnerable white matter regions.

Discussion

Inflammatory markers in post-TBI plasma samples are ambivalent with respect to prediction of favourable outcome versus a progression to more pervasive pathology and morbidity.

Anti-inflammatory interleukin 1 receptor antagonist concentration in plasma correlates with blood-brain barrier integrity in the primary lesion area in traumatic brain injury patients

Purpose

Blood-brain barrier (BBB) dysregulation and pro-inflammatory signalling molecules are secondary factors that have been associated with injury severity and long-term clinical outcome following traumatic brain injury (TBI). However, the association between BBB permeability and inflammation is unknown in human TBI patients. In this study, we investigated whether BBI integrity as measured by Dynamic Contrast-Enhanced (DCE) Magnetic Resonance Imaging (MRI) correlates with plasma levels of immunological markers following TBI.

Methods

Thirty-two TBI patients recruited from a neurosurgical unit were included in the study. Structural three-dimensional T1-weighted and DCE-MRI images were acquired on a 3T MRI at the earliest opportunity once the participant was sufficiently stable after patient admission to hospital. Blood sampling was performed on the same day as the MRI. The location and extents of the haemorrhagic and contusional lesions were identified. Immunological biomarkers were quantified from the participants' plasma using a multiplex immunoassay. Demographic and clinical information, including age and Glasgow Coma Scale (GCS) were also collected and the immunological biomarker profiles were compared across controls and the TBI severity sub-groups. Contrast agent leakiness through blood-brain barriers (BBB) in the contusional lesions were assessed by fitting DCE-MRI using Patlak model and BBB leakiness characteristics of the participants were correlated with the immunological biomarker profiles.

Results

TBI patients showed reduced plasma levels of interleukin (IL)-1β, IFN-γ, IL-13, and chemokine (C-C motif) ligands (CCL)2 compared to controls and significantly higher levels of platelet-derived growth factor (PDGF-BB), IL-6, and IL-8. BBB leakiness of the contusional lesions did not significantly differ across different TBI severity sub-groups. IL-1ra levels significantly and positively correlated with the contusional lesion's BBB integrity as measured with DCE-MRI via an exponential curve relationship.

Discussion

This is the first study to combine DCE-MRI with plasma markers of inflammation in acute TBI patients. Our finding that plasma levels of the anti-inflammatory cytokine IL-1ra correlated negatively with increased leakiness of the BBB.

Inflammation biomarkers IL‑6 and IL‑10 may improve the diagnostic and prognostic accuracy of currently authorized traumatic brain injury tools

Traumatic brain injury (TBI) is currently one of the leading causes of mortality and disability worldwide. At present, no reliable inflammatory or specific molecular neurobiomarker exists in any of the standard models proposed for TBI classification or prognostication. Therefore, the present study was designed to assess the value of a group of inflammatory mediators for evaluating acute TBI, in combination with clinical, laboratory and radiological indices and prognostic clinical scales. In the present single-centre, prospective observational study, 109 adult patients with TBI, 20 adult healthy controls and a pilot group of 17 paediatric patients with TBI from a Neurosurgical Department and two intensive care units of University General Hospital of Heraklion, Greece were recruited. Blood measurements using the ELISA method, of cytokines IL-6, IL-8 and IL-10, ubiquitin C-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein, were performed. Compared with those in healthy control individuals, elevated IL-6 and IL-10 but reduced levels of IL-8 were found on day 1 in adult patients with TBI. In terms of TBI severity classifications, higher levels of IL-6 (P=0.001) and IL-10 (P=0.009) on day 1 in the adult group were found to be associated with more severe TBI according to widely used clinical and functional scales. Moreover, elevated IL-6 and IL-10 in adults were found to be associated with more serious brain imaging findings (rs<0.442; P<0.007). Subsequent multivariate logistic regression analysis in adults revealed that early-measured (day 1) IL-6 [odds ratio (OR)=0.987; P=0.025] and UCH-L1 (OR=0.993; P=0.032) are significant independent predictors of an unfavourable outcome. In conclusion, results from the present study suggest that inflammatory molecular biomarkers may prove to be valuable diagnostic and prognostic tools for TBI.

Role of tRNA-Derived Fragments in Neurological Disorders: a Review

tRFs are small tRNA derived fragments that are emerging as novel therapeutic targets and regulatory molecules in the pathophysiology of various neurological disorders. These are derived from precursor or mature tRNA, forming different subtypes that have been reported to be involved in neurological disorders like stroke, Alzheimer's, epilepsy, Parkinson's, MELAS, autism, and Huntington's disorder. tRFs were earlier believed to be random degradation debris of tRNAs. The significant variation in the expression level of tRFs in disease conditions indicates their salient role as key players in regulation of these disorders. Various animal studies are being carried out to decipher their exact role; however, more inputs are required to transform this research knowledge into clinical application. Future investigations also call for high-throughput technologies that could help to bring out the other hidden aspects of these entities. However, studies on tRFs require further research efforts to overcome the challenges posed in quantifying tRFs, their interactions with other molecules, and the exact mechanism of function. In this review, we are abridging the current understanding of tRFs, including their biogenesis, function, relevance in clinical therapies, and potential as diagnostic and prognostic biomarkers of these neurological disorders.

Recombinant High-Density Lipoprotein Boosts the Therapeutic Efficacy of Mild Hypothermia in Traumatic Brain Injury

Traumatic brain injury (TBI) leads to neuropsychiatric symptoms and increased risk of neurodegenerative disorders. Mild hypothermia is commonly used in patients suffering from severe TBI. However, its effect for long-term protection is limited, mostly because of its insufficient anti-inflammatory and neuroprotective efficacy and restricted treatment duration. Recombinant high-density lipoprotein (rHDL), which possesses anti-inflammatory and antioxidant activity and blood-brain barrier (BBB) permeability, was expected to potentially strengthen the therapeutic effect of mild hypothermia in TBI treatment. To test this hypothesis and optimize the regimen for combination therapy, the efficacy of mild hypothermia plus concurrent or sequential rHDL on oxidative stress, inflammatory reaction, and cell survival in the damaged brain cells was evaluated. It was found that the effect of combining mild hypothermia with concurrent rHDL was modest, as mild hypothermia inhibited the cellular uptake and lesion-site-targeting delivery of rHDL. In contrast, the combination of mild hypothermia with sequential rHDL more powerfully improved the anti-inflammatory and antioxidant activities, promoted nerve cell survival and BBB restoration, and ameliorated neurologic changes, which thus remarkably restored the spatial learning and memory ability of TBI mice. Collectively, these findings suggest that rHDL may serve as a novel nanomedicine for adjunctive therapy of TBI and highlight the importance of timing of combination therapy for optimal treatment outcome.

Anti-SARS-CoV-2 S-RBD IgG Antibody Responses after COVID-19 mRNA Vaccine in the Chronic Disorder of Consciousness: A Pilot Study

OBJECTIVE

In the last year, a large amount of research has investigated the anti-spike protein receptor-binding domain (S-RBD) antibody responses in patients at high risk of developing severe acute respiratory syndrome because of COVID-19 infection. However, no data are available on the chronic disorder of consciousness (DOC).

METHODS

Here, we evaluated anti-S-RBD IgG levels after vaccination in chronic DOC patients compared with demographically matched healthy controls (HC) by indirect chemiluminescence immunoassay. All individuals completed a two-dose-cycle vaccination with Pfizer mRNA vaccine (BNT162b2), and antibody responses were evaluated at 30 and 180 days after the administration of the second dose of vaccination.

RESULTS

We compared 32 DOC patients with 34 demographically matched healthy controls. Both DOC and HC groups showed a similar antibody response at 30 days, whereas at follow-up (180 days) DOC patients were characterized by lower S-RBD IgG levels with respect to controls. Additional multiple regression analyses including demographical and clinical comorbidities as predictors revealed that age was the only factor associated with the decrease in S-RBD IgG levels at follow-up (180 days). Elderly individuals of both groups were characterized by a reduction in the antibody responses with respect to younger individuals.

CONCLUSIONS

Our results show an efficacy seroconversion in DOC patients in the first period after vaccination, which significantly declines over time with respect to healthy controls.

Electrochemical Immunosensing of Interleukin-6 in Human Cerebrospinal Fluid and Human Serum as an Early Biomarker for Traumatic Brain Injury

In this work, we develop a label-free electrochemical immunosensor for the detection of interleukin-6 (IL-6) in human cerebrospinal fluid (CSF) and serum for diagnostic and therapeutic monitoring. The IL-6 immunosensor is fabricated from gold interdigitated electrode arrays (IDEAs) that are modified with IL-6 antibodies for direct antigen recognition and capture. A rigorous surface analysis of the sensor architecture was conducted to ensure high structural fidelity and performance. Electrochemical characterization was conducted by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and sensing was performed using differential pulse voltammetry (DPV). The DPV peak current was used to quantify IL-6 in buffer, CSF, and serum in the range 1 pg mL^-1 < [IL-6] < 1 μg mL^-1. The IL-6 IDEA sensor achieved a limit of detection (LOD) of 1.63 pg mL^-1 in PBS, 2.34 pg mL^-1 in human CSF, and 11.83 pg mL^-1 in human serum. The sensor response is linear in the concentration range 10 pg mL^-1 < [IL-6] < 10 ng mL^-1, and the sensor is selective for IL-6 over other common cytokines, including IL-10 and TNF-α. EIS measurements showed that the resistance to charge transfer, R _CT, decreases upon IL-6 binding, an observation attributed to a structural change upon Ab-Ag binding that opens up the architecture so that the redox probe can more easily access the electrode surface. The IL-6 IDEA sensor can be used as a point-of-care diagnostic tool to deliver rapid results (∼3 min) in clinical settings for traumatic brain injury, and potentially address the unmet need for effective diagnostic and prognostic tools for other cytokine-related illnesses, such as sepsis and COVID-19 induced cytokine storms. Given the interdigitated electrode form factor, it is likely that the performance of the sensor can be further improved through redox cycling.

Systemic inflammation alters the neuroinflammatory response: a prospective clinical trial in traumatic brain injury

Background

Neuroinflammation following traumatic brain injury (TBI) has been shown to be associated with secondary injury development; however, how systemic inflammatory mediators affect this is not fully understood. The aim of this study was to see how systemic inflammation affects markers of neuroinflammation, if this inflammatory response had a temporal correlation between compartments and how different compartments differ in cytokine composition.

Methods

TBI patients recruited to a previous randomised controlled trial studying the effects of the drug anakinra (Kineret®), a human recombinant interleukin-1 receptor antagonist (rhIL1ra), were used (n = 10 treatment arm, n = 10 control arm). Cytokine concentrations were measured in arterial and jugular venous samples twice a day, as well as in microdialysis-extracted brain extracellular fluid (ECF) following pooling every 6 h. C-reactive protein level (CRP), white blood cell count (WBC), temperature and confirmed systemic clinical infection were used as systemic markers of inflammation. Principal component analyses, linear mixed-effect models, cross-correlations and multiple factor analyses were used.

Results

Jugular and arterial blood held similar cytokine information content, but brain-ECF was markedly different. No clear arterial to jugular gradient could be seen. No substantial delayed temporal associations between blood and brain compartments were detected. The development of a systemic clinical infection resulted in a significant decrease of IL1-ra, G-CSF, PDGF-ABBB, MIP-1b and RANTES (p < 0.05, respectively) in brain-ECF, even if adjusting for injury severity and demographic factors, while an increase in several cytokines could be seen in arterial blood.

Conclusions

Systemic inflammation, and infection in particular, alters cytokine levels with different patterns seen in brain and in blood. Cerebral inflammatory monitoring provides independent information from arterial and jugular samples, which both demonstrate similar information content. These findings could present potential new treatment options in severe TBI patients, but novel prospective trials are warranted to confirm these associations.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02264-2.

The Peripheral Immune System and Traumatic Brain Injury: Insight into the role of T-helper cells

Emerging evidence suggests that immune-inflammatory processes are key elements in the physiopathological events associated with traumatic brain injury (TBI). TBI is followed by T-cell-specific immunological changes involving several subsets of T-helper cells and the cytokines they produce; these processes can have opposite effects depending on the disease course and cytokine concentrations. Efforts are underway to identify the T-helper cells and cytokine profiles associated with prognosis. These predictors may eventually serve as effective treatment targets to decrease morbidity and mortality and to improve the management of TBI patients. Here, we review the immunological response to TBI, the possible molecular mechanisms of this response, and therapeutic strategies to address it.

Association of Serum IL-6 (Interleukin 6) With Functional Outcome After Intracerebral Hemorrhage

BACKGROUND AND OBJECTIVES

IL-6 (interleukin 6) is a proinflammatory cytokine and an established biomarker in acute brain injury. We sought to determine whether admission IL-6 levels are associated with severity and functional outcome after spontaneous intracerebral hemorrhage (ICH).

METHODS

We performed an exploratory analysis of the recombinant activated FAST trial (Factor VII for Acute ICH). Patients with admission serum IL-6 levels were included. Regression analyses were used to assess the associations between IL-6 and 90-day modified Rankin Scale. In secondary analyses, we used linear regression to evaluate the association between IL-6 and baseline ICH and perihematomal edema volumes.

RESULTS

Of 841 enrolled patients, we included 552 (66%) with available admission IL-6 levels (mean age 64 [SD 13], female sex 203 [37%]). IL-6 was associated with poor outcome (modified Rankin Scale, 4-6; per additional 1 ng/L, odds ratio, 1.30 [95% CI, 1.04-1.63]; P=0.02) after adjustment for known predictors of outcome after ICH and treatment group. IL-6 was associated with ICH volume after adjustment for age, sex, and ICH location, and this association was modified by location (multivariable interaction, P=0.002), with a stronger association seen in lobar (β, 12.51 [95% CI, 6.47-18.55], P<0.001) versus nonlobar (β 5.32 [95% CI, 3.36-7.28], P<0.001) location. IL-6 was associated with perihematomal edema volume after adjustment for age, sex, ICH volume, and ICH location (β 1.22 [95% CI, 0.15-2.29], P=0.03). Treatment group was not associated with IL-6 levels or outcome.

CONCLUSIONS

In the FAST trial population, higher admission IL-6 levels were associated with worse 90-day functional outcome and larger ICH and perihematomal edema volumes.

Can brain natriuretic peptide, S100b, and interleukin-6 prognosticate the neurological consequences in Egyptian patients presented with supratentorial intracerebral hemorrhage?

Background:

Biomarkers in supratentorial intracerebral hemorrhage (SICH) enhance the prognosis of the disease. This study aimed to assess the prognosticative grade of S100 calcium-binding protein B (S100B), interleukin-6 (IL-6), and the pro-brain natriuretic peptide (pro-BNP) in SICH outcome prediction.

Methods:

Blood samples of 50 SICH patients were analyzed for the biomarkers. The patients were classified into two groups with and without intraventricular hemorrhage (IVH). The following scales including Glasgow Coma Score (GCS), the Barthel index (BI), intracerebral hemorrhage (ICH) score, ICH volume, National Institutes of Health Stroke Scale (NIHSS), Modified Rankin Score (mRS), and length of stay were used to evaluate the severity.

Results:

The severity scores (NIHSS, GCS, BI, mRI) were significantly higher in SICH patients with IVH versus SICH patients without IVH (P = 0.002, 0.008, 0.001, and 0.03, respectively). Serum levels for a pro-BNP and S100b are significantly higher in SICH patients with IVH versus SICH patients without IVH (P = 0.02 and 0.027, respectively). Multivariate correlations between demographic (age), biomarkers panel (IL-6, S100b, and proBNP), and clinical and severity scores (ICH score, ICH volume, length of hospital stay [LOS], BI, mRS, GCS, and NIHSSS) in all studied patients showed a highly significant correlation between ICH score and pro-BNP (P = 0.04). There was a highly significant correlation between LOS and IL-6 (P = 0.003).

Conclusion:

Pro-BNP, IL-6, and S100b are greatly associated with the presence of IVH that, in turn, correlated well with poor clinical outcome measures.

miR-7-5p Affects Brain Edema After Intracerebral Hemorrhage and Its Possible Mechanism

Objective: To explore the relationship between miR-7-5p and brain edema after intracerebral hemorrhage and the role of butylphthalide (NBP) in brain edema after intracerebral hemorrhage. Method: Routine blood testing, C-reactive protein results, and computed tomography data were collected 1, 7, and 14 days after intracerebral hemorrhage in six patients. Levels of MMP-9, ZO-1, occludin, IL-6, TNF-α, and miR-7-5p were detected in each patient's serum. Sixty male Sprague-Dawley rats were randomly divided into sham operation, intracerebral hemorrhage, and NBP treatment groups. Dry-wet weight was used to assess brain edema, and Evans blue staining was used to assess the permeability of the blood-brain barrier. Expression levels of IL-6, TNF-α, ZO-1 and occludin, PI3K, AKT, p-AKT, AQP4, and miR-7-5p were analyzed in the rat brains. Result: The blood neutrophil-lymphocyte ratio (NLR) on day 1 was associated with the area of brain edema on day 7. The expression of miR-7-5p decreased after intracerebral hemorrhage, and as a result, the inhibition of the PI3K/AKT pathway was weakened. The decreased inhibition of the PI3K/AKT pathway resulted in an increase in AQP4 expression, which further aggravated brain edema. NBP can upregulate the expression of miR-7-5p, affecting these pathways to reduce brain edema. Conclusion: After intracerebral hemorrhage, miR-7-5p expression in brain tissue is reduced, which may increase the expression of AQP4 by activating the PI3K/AKT pathway. NBP can inhibit this process and reduce brain edema.

Comparison of Propofol and Sevoflurane on Cerebral Oxygenation Using Juglar Venous Oximetery (SjVo2) in Patients Undergoing Surgery for Traumatic Brain Injury

Background:

Traumatic brain injury (TBI) induces major insult to the normal cerebral physiology. The anesthetic agents may infrequently produce deleterious effects and further aggravate damage to the injured brain. This study was conducted to evaluate the effects of propofol and sevoflurane on cerebral oxygenation, brain relaxation, systemic hemodynamic parameters and levels of interleukin-6 (IL-6) in patients with severe TBI undergoing decompressive craniectomy.

Methods:

A prospective randomized comparative study was conducted on 42 patients undergoing surgery for severe TBI. Patients were randomized into two groups, Group P received propofol and Group S received sevoflurane for maintenance of anesthesia. All patients were induced with fentanyl, propofol, and vecuronium. The effect of these agents on cerebral oxygenation was assessed by jugular venous oxygen saturation (SjVO₂). Hemodynamic changes and quality of intraoperative brain relaxation were also assessed. The serum levels of IL-6 were quantitated using enzyme-linked immunosorbent assay technique.

Results:

SjVO₂ values were comparable and mean arterial pressure (MAP) was found to be significantly lower in Group P as compared to those in Group S (P < 0.05). Brain relaxation scores were comparable between the groups. The level of IL-6 decreased significantly at the end of surgery compared to baseline in patients receiving sevoflurane (P = 0.040).

Conclusions:

Cerebral oxygenation measured by SjVO₂ was comparable when anesthesia was maintained with propofol or sevoflurane. However, significant reduction in MAP by propofol needs attention in patients with severe TBI. The decrease in IL-6 level reflects anti-inflammatory effect and probable neuroprotective potential of propofol and sevoflurane.

Severe Traumatic Brain Injury (TBI) Modulates the Kinetic Profile of the Inflammatory Response of Markers for Neuronal Damage

The inflammatory response plays an important role in the pathophysiology of multiple injuries. This study examines the effects of severe trauma and inflammatory response on markers of neuronal damage. A retrospective analysis of prospectively collected data in 445 trauma patients (Injury Severity Score (ISS) ≥ 16) is provided. Levels of neuronal biomarkers (calcium-binding Protein B (S100b), Enolase2 (NSE), glial fibrillary acidic protein (GFAP)) and Interleukins (IL-6, IL-10) in severely injured patients (with polytrauma (PT)) without traumatic brain injury (TBI) or with severe TBI (PT+TBI) and patients with isolated TBI (isTBI) were measured upon arrival until day 5. S100b, NSE, GFAP levels showed a time-dependent decrease in all cohorts. Their expression was higher after multiple injuries (p = 0.038) comparing isTBI. Positive correlation of marker level after concomitant TBI and isTBI (p = 0.001) was noted, while marker expression after PT appears to be independent. Highest levels of IL-6 and -10 were associated to PT und lowest to isTBI (p < 0.001). In all groups pro-inflammatory response (IL-6/-10 ratio) peaked on day 2 and at a lower level on day 4. Severe TBI modulates kinetic profile of inflammatory response by reducing interleukin expression following trauma. Potential markers for neuronal damage have a limited diagnostic value after severe trauma because undifferentiated increase.

Moderate Hypothermic Circulatory Arrest Is Preferable During Cardiopulmonary Bypass

The effect of temperature on cerebral injury during hypothermic circulatory arrest (HCA) has never been specifically studied. This study aimed to compare the effects of two different temperatures used for HCA on the degree of brain injury in pig models. Thirteen pigs were randomly assigned to a deep hypothermic circulatory arrest (DHCA) group (n = 5), moderate hypothermic circulatory arrest (MHCA) group (n = 5), or control group (n = 3). No significant differences in immunohistochemical assay results, including Bax, Bcl-2, and Caspase 3 staining, and a TUNEL assay, were observed between the DHCA and MHCA groups. Furthermore, no significant difference was found for biomarkers of brain injury (Soluble protein-100B) between the two experimental groups. Similarly, no significant difference was observed in the trend of changes in inflammatory factors, including tumor necrosis factor-α, interleukin (IL)-2, and IL-6, between the two groups (p > 0.05). However, coagulation factors, including FXI and FVII, were different between the DHCA and MHCA groups (p < 0.05). Therefore, it can be concluded that MHCA does not increase the risk of cerebral injury. Considering the adverse effects of DHCA on the coagulation system, MHCA is more suitable for current clinical practice.

Interleukin-6 is associated with acute concussion in military combat personnel

BACKGROUND

Concussion is the most common type of TBI, yet reliable objective measures related to these injuries and associated recovery processes remain elusive, especially in military personnel. The purpose of this study was to characterize the relationship between cytokines and recovery from acute brain injury in active duty service members. Inflammatory cytokines (IL-6, IL-10, and TNFα) were measured acutely in blood samples within 8 h following a medically diagnosed concussion and then 24 h later.

METHODS

Participants (n = 94) were categorized into two groups: 1) military personnel who sustained provider-diagnosed concussion, without other major medical diagnosis (n = 45) and 2) healthy control participants in the same deployment environment who did not sustain concussion or other illness or injuries (n = 49). IL-6, IL-10, and TNFα concentrations were measured using an ultrasensitive single-molecule enzyme-linked immunosorbent assay. Differences in cytokine levels between concussed and healthy groups were evaluated at two time points (time point 1 ≤ 8 h after injury; time point 2 = 24 h following time point 1).

RESULTS

At time point 1, IL-6 median (IQR) concentrations were 2.62 (3.62) in the concussed group, which was greater compared to IL-6 in the healthy control group (1.03 (0.90); U = 420.00, z = - 5.12, p < 0.001). Compared to healthy controls, the concussed group did not differ at time point 1 in IL-10 or TNFα concentrations (p's > 0.05). At time point 2, no differences were detected between concussed and healthy controls for IL-6, IL-10, or TNFα (p's > 0.05). The median difference between time points 1 and 2 were compared between the concussed and healthy control groups for IL-6, IL-10, and TNFα. Change in IL-6 across time was greater for the concussed group than healthy control (- 1.54 (3.12); U = 315.00, z = - 5.96, p < 0.001), with no differences between groups in the change of IL-10 or TNFα (p's > 0.05).

CONCLUSION

Reported here is a significant elevation of IL-6 levels in concussed military personnel less than 8 h following injury. Future studies may examine acute and chronic neurological symptomology associated with inflammatory cytokine levels, distinguish individuals at high risk for developing neurological complications, and identify underlying biological pathways to mitigate inflammation and improve outcomes.

Pithecellobium clypearia extract enriched in gallic acid and luteolin has antibacterial activity against MRSA and reduces resistance to erythromycin, ceftriaxone sodium and levofloxacin

AIMS

Antibiotic adjuvants can give a second life to the antibiotics to which bacteria are highly resistant. We evaluated the antimicrobial effects of extracts from Pithecellobium clypearia against methicillin-resistant Staphylococcus aureus (MRSA) and also the potential for synergy with several antibiotics.

METHODS AND RESULTS

For this study, four extracts from P. clypearia were tested on MRSA using the broth microdilution method for activity assessment. The ethyl acetate fraction (S20b) had the strongest antibacterial activity against MRSA among the fractions tested. In all, 14 compounds such as gallic acid and luteolin in S20b were analysed by UFLC-Q-TOF-MS/MS. S20b combined with erythromycin showed synergy effects against MRSA and combined with ceftriaxone sodium and levofloxacin showed additive effects against MRSA. Electron microscopy showed that extract S20b damaged the MRSA cell wall and K⁺ efflux measurements indicated that extract S20b increased cell membrane permeability. Moreover, S20b suppression of PBP2a expression was assessed by Western blot. Furthermore, an in vivo study was used to investigate the therapeutic potential of S20b based on a mouse pneumonia model.

CONCLUSIONS

The in vitro study results have shown that S20b not only inhibits MRSA growth directly but also reduces the resistance of MRSA to the evaluated antibacterial agents. Based on the in vivo study, it can be concluded that S20b can treat pneumonia in the mouse model.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is the first research to demonstrate that S20b can inhibit MRSA growth and reduce drug resistance of clinical isolates to antibiotics. S20b has the potential to be used as a therapeutic agent against MRSA and treatment for MRSA pneumonia.

Identification of target genes in neuroinflammation and neurodegeneration after traumatic brain injury in rats

Background

Traumatic brain injury (TBI) is a common neurological emergency observed in hospitals. A considerable number of patients suffer from long-term disabilities after TBI. This study aimed to identify altered gene expression signatures and mechanisms related to TBI-induced chronic neuroinflammation and neurodegeneration.

Methods

An integrated analysis was performed using published RNA-sequencing studies to determine TBI-induced differentially expressed genes (DEGs). Based on the DEG data, functional annotation, signal-net, and transcription factor analyses were conducted to understand the mechanism of chronic neuroinflammation and neurodegeneration induced after TBI.

Results

Two datasets were obtained using the Gene Expression Omnibus database, of which, 6,513 DEGs were identified (6,464 upregulated and 49 downregulated). Positive regulation of biological process, positive regulation of cellular process, nucleus, and heterocyclic compound binding were Gene Ontology terms significantly enriched in post-TBI rat models. Leukocyte transendothelial migration, chemokine signaling pathway, neurotrophin signaling pathway, and longevity-regulating pathway were significantly enriched after TBI. With regard to the signal-net analysis, FOXO3, DGKZ and ILK were considered the most critical genes derived using high–betweenness centrality calculation. A total of 44 TFs, including FOXO1, SRY and KLF4, were predicted to play an important role in the upregulation of gene expression. Using integrated bioinformatics analysis, TBI was found to be associated with a significant inflammatory response and neurodegeneration. FOXO3, apolipoprotein (APOE), microtubule-associated protein tau (MAPT), and TREM2 were probably associated with the TBI pathological process. The mitochondrial electron transport chain may be associated with neurodegeneration in patients with TBI, serving as a potential therapeutic target.

Cortisol total/CRP ratio for the prediction of hospital-acquired pneumonia and initiation of corticosteroid therapy in traumatic brain-injured patients

BACKGROUND

To propose a combination of blood biomarkers for the prediction of hospital-acquired pneumonia (HAP) and for the selection of traumatic brain-injured (TBI) patients eligible for corticosteroid therapy for the prevention of HAP.

METHODS

This was a sub-study of the CORTI-TC trial, a multicenter, randomized, double-blind, controlled trial evaluating the risk of HAP at day 28 in 336 TBI patients treated or not with corticosteroid therapy. Patients were between 15 and 65 years with severe traumatic brain injury (Glasgow coma scale score ≤ 8 and trauma-associated lesion on brain CT scan) and were enrolled within 24 h of trauma. The blood levels of CRP and cortisoltotal&free, as a surrogate marker of the pro/anti-inflammatory response balance, were measured in samples collected before the treatment initiation. Endpoint was HAP on day 28.

RESULTS

Of the 179 patients with available samples, 89 (49.7%) developed an HAP. Cortisoltotal&free and CRP blood levels upon ICU admission were not significantly different between patients with or without HAP. The cortisoltotal/CRP ratio upon admission was 2.30 [1.25-3.91] in patients without HAP and 3.36 [1.74-5.09] in patients with HAP (p = 0.021). In multivariate analysis, a cortisoltotal/CRP ratio > 3, selected upon the best Youden index on the ROC curve, was independently associated with HAP (OR 2.50, CI95% [1.34-4.64] p = 0.004). The HR for HAP with corticosteroid treatment was 0.59 (CI95% [0.34-1.00], p = 0.005) in patients with a cortisoltotal/CRP ratio > 3, and 0.89 (CI95% [0.49-1.64], p = 0.85) in patients with a ratio < 3.

CONCLUSION

A cortisoltotal/CRP ratio > 3 upon admission may predict the development of HAP in severe TBI. Among these patients, corticosteroids reduce the occurrence HAP. We suggest that this ratio may select the patients who may benefit from corticosteroid therapy for the prevention of HAP.

Peripheral loss of EphA4 ameliorates TBI-induced neuroinflammation and tissue damage

BACKGROUND

The continuum of pro- and anti-inflammatory response elicited by traumatic brain injury (TBI) is suggested to play a key role in the outcome of TBI; however, the underlying mechanisms remain ill -defined.

METHODS

Here, we demonstrate that using bone marrow chimeric mice and systemic inhibition of EphA4 receptor shifts the pro-inflammatory milieu to pro-resolving following acute TBI.

RESULTS

EphA4 expression is increased in the injured cortex as early as 2 h post-TBI and on CX3CR1^gfp-positive cells in the peri-lesion. Systemic inhibition or genetic deletion of EphA4 significantly reduced cortical lesion volume and shifted the inflammatory profile of peripheral-derived immune cells to pro-resolving in the damaged cortex. These findings were consistent with in vitro studies showing EphA4 inhibition or deletion altered the inflammatory state of LPS-stimulated monocyte/macrophages towards anti-inflammatory. Phosphoarray analysis revealed that EphA4 may regulate pro-inflammatory gene expression by suppressing the mTOR, Akt, and NF-κB pathways. Our human metadata analysis further demonstrates increased EPHA4 and pro-inflammatory gene expression, which correlates with reduced AKT concurrent with increased brain injury severity in patients.

CONCLUSIONS

Overall, these findings implicate EphA4 as a novel mediator of cortical tissue damage and neuroinflammation following TBI.

In Vitro and In Vivo Pipeline for Validation of Disease-Modifying Effects of Systems Biology-Derived Network Treatments for Traumatic Brain Injury-Lessons Learned

We developed a pipeline for the discovery of transcriptomics-derived disease-modifying therapies and used it to validate treatments in vitro and in vivo that could be repurposed for TBI treatment. Desmethylclomipramine, ionomycin, sirolimus and trimipramine, identified by in silico LINCS analysis as candidate treatments modulating the TBI-induced transcriptomics networks, were tested in neuron-BV2 microglial co-cultures, using tumour necrosis factor α as a monitoring biomarker for neuroinflammation, nitrite for nitric oxide-mediated neurotoxicity and microtubule associated protein 2-based immunostaining for neuronal survival. Based on (a) therapeutic time window in silico, (b) blood-brain barrier penetration and water solubility, (c) anti-inflammatory and neuroprotective effects in vitro (p < 0.05) and (d) target engagement of Nrf2 target genes (p < 0.05), desmethylclomipramine was validated in a lateral fluid-percussion model of TBI in rats. Despite the favourable in silico and in vitro outcomes, in vivo assessment of clomipramine, which metabolizes to desmethylclomipramine, failed to demonstrate favourable effects on motor and memory tests. In fact, clomipramine treatment worsened the composite neuroscore (p < 0.05). Weight loss (p < 0.05) and prolonged upregulation of plasma cytokines (p < 0.05) may have contributed to the worsened somatomotor outcome. Our pipeline provides a rational stepwise procedure for evaluating favourable and unfavourable effects of systems-biology discovered compounds that modulate post-TBI transcriptomics.

Metabolomics and Biomarker Discovery in Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of disability and mortality worldwide. The TBI pathogenesis can induce broad pathophysiological consequences and clinical outcomes attributed to the complexity of the brain. Thus, the diagnosis and prognosis are important issues for the management of mild, moderate, and severe forms of TBI. Metabolomics of readily accessible biofluids is a promising tool for establishing more useful and reliable biomarkers of TBI than using clinical findings alone. Metabolites are an integral part of all biochemical and pathophysiological pathways. Metabolomic processes respond to the internal and external stimuli resulting in an alteration of metabolite concentrations. Current high-throughput and highly sensitive analytical tools are capable of detecting and quantifying small concentrations of metabolites, allowing one to measure metabolite alterations after a pathological event when compared to a normal state or a different pathological process. Further, these metabolic biomarkers could be used for the assessment of injury severity, discovery of mechanisms of injury, and defining structural damage in the brain in TBI. Metabolic biomarkers can also be used for the prediction of outcome, monitoring treatment response, in the assessment of or prognosis of post-injury recovery, and potentially in the use of neuroplasticity procedures. Metabolomics can also enhance our understanding of the pathophysiological mechanisms of TBI, both in primary and secondary injury. Thus, this review presents the promising application of metabolomics for the assessment of TBI as a stand-alone platform or in association with proteomics in the clinical setting.

The Relationship between Serum Concentrations of Pro- and Anti-Inflammatory Cytokines and Nutritional Status in Patients with Traumatic Head Injury in the Intensive Care Unit

Background and objective: The aim of the present study was to examine the relationship between serum levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) and anti-inflammatory cytokines (IL-10) measured once at the baseline with changes in nutritional status of patients with traumatic head injury (THI) assessed at three consecutive times (24 h after admission, day 6 and day 13) during hospital stay in the intensive care unit (ICU). Materials and Methods: Sixty-four patients with THI were recruited for the current study (over 10 months). The nutritional status of the patients was determined within 24 h after admission and on days 6 and 13, using actual body weight, body composition analysis, and anthropometric measurements. The APACHE II score and SOFA score were also assessed within 24 h of admission and on days 6 and 13 of patients staying in the ICU. Circulatory serum levels of cytokines (IL-6, IL-1β, TNF-α, and IL-10) were assessed once within 24 h of admission. Results: The current study found a significant reduction in BMI, FBM, LBM, MAUAC, and APM, of THI patients with high serum levels the cytokines, over the course of time from the baseline to day 7 and to day 13 in patients staying in the ICU (p < 0.001). It was also found that patients with low levels of some studied cytokines had significant improvement in their nutritional status and clinical outcomes in term of MAUAC, APM, APACHE II score and SOFA score (p < 0.001 to p < 0.01). Conclusion: THI patients who had high serum levels of studied cytokines were more prone to develop a reduction of nutritional status in terms of BMI, FBM, LBM MAUAC and APM over the course of time from patient admission until day 13 of ICU admission.

Acute changes of pro-inflammatory markers and corticosterone in experimental subarachnoid haemorrhage: A prerequisite for severity assessment

Many details of the pathophysiology of subarachnoid haemorrhage (SAH) still remain unknown, making animal experiments an indispensable tool for assessment of diagnostics and therapy. For animal protection and project authorization, one needs objective measures to evaluate the severity and burden in each model. Corticosterone is described as a sensitive stress parameter reflecting the acute burden, and inflammatory markers can be used for assessment of the extent of the brain lesion. However, the brain lesion itself may activate the hypothalamic-pituitary-adrenal-axis early after SAH, as shown for ischemic stroke, probably interfering with early inflammatory processes, thus complicating the assessment of severity and burden on the basis of corticosterone and inflammation. To assess the suitability of these markers in SAH, we evaluated the courses of corticosterone, IL-6 and TNF-α up to 6h in an acute model simulating SAH in continuously anaesthetized rats, lacking the pain and stress induced impact on these parameters. Animals were randomly allocated to sham or SAH. SAH was induced by cisterna magna blood-injection, and intracranial pressure and cerebral blood flow were measured under continuous isoflurane/fentanyl anaesthesia. Withdrawn at predetermined time points, blood was analysed by commercial ELISA kits. After 6h the brain was removed for western blot analysis of IL-6 and TNF-α. Serum corticosterone levels were low with no significant difference between sham and SAH. No activation of the HPA-axis was detectable, rendering corticosterone a potentially useful parameter for stress assessment in future chronic studies. Blood IL-6 and TNF-α increased in both groups over time, with IL-6 increasing significantly more in SAH compared to sham towards the end of the observation period. In the basal cortex, IL-6 and TNF-α increased only in SAH. The pro-inflammatory response seems to start locally in the brain, reflected by an increase in peripheral blood. An additional surgery-induced systemic inflammatory response should be considered.

Pituitary disease in pediatric brain tumor survivors

INTRODUCTION

Treatment of childhood brain tumors, including surgical resection and especially external beam radiation, often results in endocrine complications manifested by hypopituitarism, which can involve growth hormone deficiency, hypothyroidism, adrenal insufficiency, disorders of puberty, diabetes insipidus, and hypothalamic obesity.

AREAS COVERED

A comprehensive literature search was conducted on Medline (publications from the 1990s to 01/2019) including systematic reviews, meta-analyses, longitudinal controlled studies, retrospective cohort studies, and case reports. Herein, we present an up-to-date review of the current literature regarding endocrine sequellae of childhood brain tumor survivors.

EXPERT OPINION

Late endocrine sequellae can arise many years after the initial treatment of tumor, so at least annual surveillance of growth, puberty, weight, development, and endocrine status is recommended for at least 10 years after tumor therapy. This follow up should encompass childhood and adulthood among survivors. If found early, outcomes of endocrinopathies are favorable when treated appropriately. Newer tumor therapy modalities, such as proton beam radiation, offer the potential for fewer endocrine complications, but such benefit has yet to be demonstrated, and more research into short- and long-term outcomes is needed.

Systemic inflammation in hemorrhagic strokes - A novel neurological sign and therapeutic target?

Growing evidences suggest that stroke is a systemic disease affecting many organ systems beyond the brain. Stroke-related systemic inflammatory response and immune dysregulations may play an important role in brain injury, recovery, and stroke outcome. The two main phenomena in stroke-related peripheral immune dysregulations are systemic inflammation and post-stroke immunosuppression. There is emerging evidence suggesting that the spleen contracts following ischemic stroke, activates peripheral immune response and this may further potentiate brain injury. Whether similar brain-immune crosstalk occurs in hemorrhagic strokes such as intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) is not established. In this review, we systematically examined animal and human evidence to date on peripheral immune responses associated with hemorrhagic strokes. Specifically, we reviewed the impact of clinical systemic inflammatory response syndrome (SIRS), inflammation- and immune-associated biomarkers, the brain-spleen interaction, and cellular mediators of peripheral immune responses to ICH and SAH including regulatory T cells (Tregs). While there is growing data suggesting that peripheral immune dysregulation following hemorrhagic strokes may be important in brain injury pathogenesis and outcome, details of this brain-immune system cross-talk remain insufficiently understood. This is an important unmet scientific need that may lead to novel therapeutic strategies in this highly morbid condition.

Acute Tubular Injury is Associated With Severe Traumatic Brain Injury: in Vitro Study on Human Tubular Epithelial Cells

Acute kidney injury following traumatic brain injury is associated with poor outcome. We investigated in vitro the effects of plasma of brain injured patients with acute tubular kidney injury on kidney tubular epithelial cell function. we performed a prospective observational clinical study in ICU in a trauma centre of the University hospital in Italy including twenty-three ICU patients with traumatic brain injury consecutively enrolled. Demographic data were recorded on admission: age 39 ± 19, Glasgow Coma Score 5 (3–8). Neutrophil Gelatinase-Associated Lipocalin and inflammatory mediators were measured in plasma on admission and after 24, 48 and 72 hours; urine were collected for immunoelectrophoresis having healthy volunteers as controls. Human renal proximal tubular epithelial cells were stimulated with patients or controls plasma. Adhesion of freshly isolated human neutrophils and trans-epithelial electrical resistance were assessed; cell viability (XTT assay), apoptosis (TUNEL staining), Neutrophil Gelatinase-Associated Lipocalin and Megalin expression (quantitative real-time PCR) were measured. All patients with normal serum creatinine showed increased plasmatic Neutrophil Gelatinase-Associated Lipocalin and increased urinary Retinol Binding Protein and α1-microglobulin. Neutrophil Gelatinase-Associated Lipocalin was significantly correlated with both inflammatory mediators and markers of tubular damage. Patient’ plasma incubated with tubular cells significantly increased adhesion of neutrophils, reduced trans-epithelial electrical resistance, exerted a cytotoxic effect and triggered apoptosis and down-regulated the endocytic receptor Megalin compared to control. Plasma of brain injured patients with increased markers of subclinical acute kidney induced a pro-inflammatory phenotype, cellular dysfunction and apoptotic death in tubular epithelial cells.

Cytokine Responses in Severe Traumatic Brain Injury: Where There Is Smoke, Is There Fire?

This scoping review will discuss the basic functions and prognostic significance of the commonly researched cytokines implicated in severe traumatic brain injury (sTBI), including tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), transforming growth factor-β (TGF-β), substance P, and soluble CD40 ligand (sCD40L). A scoping review was undertaken with an electronic search for articles from the Ovid MEDLINE, PUBMED and EMBASE databases from 1995 to 2017. Inclusion criteria were original research articles, and reviews including both animal models and human clinical studies of acute (< 3 months) sTBI. Selected articles included both isolated sTBI and sTBI with systemic injury. After applying the inclusion criteria and removing duplicates, 141 full-text articles, 126 original research articles and 15 review articles, were evaluated in compiling this review paper. A single reviewer, CC, completed the review in two phases. During the first phase, titles and abstracts of selected articles were reviewed for inclusion. A second evaluation was then conducted on the full text of all selected articles to ensure relevancy. From our current understanding of the literature, it is unlikely a single biomarker will be sufficient in accurately prognosticating patients with sTBI. Intuitively, a more severe injury will demonstrate higher levels of inflammatory cytokines which may correlate as a marker of severe injury. This does not mean, necessarily, these cytokines have a direct and causal role in the poor outcome of the patient. Further research is required to better delineate the complex systemic inflammatory and CNS interactions that occur during sTBI before they can be applied as a reliable prognostic tool.

Testing a Multivariate Proteomic Panel for Traumatic Brain Injury Biomarker Discovery: A TRACK-TBI Pilot Study

The complex and heterogeneous nature of traumatic brain injury (TBI) has rendered the identification of diagnostic and prognostic biomarkers elusive. A single acute biomarker may not be sufficient to categorize injury severity and/or predict outcome. Using multivariate dimension reduction analyses, we tested the sensitivity and specificity of a multi-analyte panel of proteins as an ensemble biomarker for TBI. Serum was collected within 24 h of injury in a cohort of 130 patients enrolled in the multi-center prospective Transforming Research and Clinical Knowledge in Traumatic Brain Injury Pilot (TRACK-TBI Pilot) study and run on an array that measured 72 proteins. Using unsupervised principal components analysis, we first identified the subset of protein changes accounting for the most variance across patients. This yielded a group of 21 proteins that reflected an inverse relationship between inflammatory cytokines and regulators of anti-inflammation, and generated an individual inflammatory profile score for each patient. We then tested the association between these scores and computed tomography (CT) findings at hospital admission, as well as their prognostic association with functional recovery at 3 and 6 months (Glasgow Outcome Scale-Extended), and cognitive recovery at 6 months (California Verbal Learning Test, Second Edition) after injury. Inflammatory signatures were significantly increased in patients with positive CT findings, as well as in those who showed poor or incomplete recovery. Inflammation biomarker scores also showed significant sensitivity and specificity as a discriminator of these outcome measures (all areas under the curve [AUCs] >0.62). This proof of concept for the feasibility of multivariate biomarker identification demonstrates the prognostic validity of using a proteomic panel as a potential biomarker for TBI.

Higher exosomal tau, amyloid-beta 42 and IL-10 are associated with mild TBIs and chronic symptoms in military personnel

OBJECTIVE

Identify biomarkers in peripheral blood that relate to chronic post-concussive and behavioural symptoms following traumatic brain injuries (TBIs) to ultimately improve clinical management.

RESEARCH DESIGN

We compared military personnel with mild TBIs (mTBIs) (n = 42) to those without TBIs (n = 22) in concentrations of tau, amyloid-beta (Aβ42) and cytokines (tumour necrosis factor alpha (TNFα, interleukin (IL)-6 and -10) in neuronal-derived exosomes from the peripheral blood. We utilized nanosight technology coupled with ultra-sensitivity immunoassay methods. We also examined the impact of post-concussive and behavioural symptoms including depression and post-traumatic stress disorder (PTSD) on these neuronal-derived markers.

RESULTS

We report that concentrations of exosomal tau (F_1, 62 = 10.50), Aβ42 (F_1, 61 = 5.32) and IL-10 (F_1, 59 = 4.32) were elevated in the mTBI group compared to the controls. Within the mTBI group, regression models show that post-concussive symptoms were most related to exosomal tau elevations, whereas exosomal IL-10 levels were related to PTSD symptoms.

CONCLUSIONS

These findings suggest that chronic post-concussive symptoms following an mTBI relate to altered exosomal activity, and that greater tau pathology may underlie chronic post-concussive symptoms that develop following mTBIs. It also suggests that central inflammatory activity contributes to PTSD symptoms following an mTBI, providing necessary insights into the role of inflammation in chronic PTSD symptoms.

Laquinimod attenuates inflammation by modulating macrophage functions in traumatic brain injury mouse model

Background

Traumatic brain injury (TBI) is a critical public health and socio-economic problem worldwide. A growing body of evidence supports the involvement of inflammatory events in TBI. It has been reported that resident microglia and infiltrating monocytes promote an inflammatory reaction that leads to neuronal death and eventually behavioral and cognitive impairment. Currently, there is no effective treatment for TBI and the development of new therapeutic strategies is a scientific goal of highest priority. Laquinimod, an orally administered neuroimmunomodulator initially developed for the treatment of multiple sclerosis, might be a promising neuroprotective therapy for TBI. Herein, we aim to investigate the hypothesis that laquinimod will reduce the central nervous system (CNS) damage caused by TBI.

Methods

To test our hypothesis, Ccr2^rfp/+Cx3cr1^gfp/+ mice were submitted to a moderate TBI induced by fluid percussion. Sham controls were submitted only to craniotomy. Mice were treated daily by oral gavage with laquinimod (25 mg/kg) 7 days before and 3 days after TBI. The brains of mice treated or not treated with laquinimod were collected at 3 and 120 days post injury, and brain morphological changes, axonal injury, and neurogenesis were evaluated by microscopy analysis. We also isolated microglia from infiltrating monocytes, and the expression of immune gene mRNAs were analyzed by employing a quantitative NanoString nCounter technique.

Results

Laquinimod prevented ventricle enlargement caused by TBI in the long term. Immunohistochemical analyses revealed decreased axonal damage and restored neurogenesis in the laquinimod-treated TBI group at early stage (3 days post injury). Notably, laquinimod inhibited the monocytes infiltration to the brain. Hierarchial clustering demonstrated that the microglial gene expression from the TBI group treated with laquinimod resembles the sham group more than the TBI-water control group.

Conclusions

Administration of laquinimod reduced lesion volume and axonal damage and restored neurogenesis after TBI. Laquinimod might be a potential therapy strategy to improve TBI long-term prognosis.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1075-y) contains supplementary material, which is available to authorized users.

Early fever after trauma: Does it matter?

BACKGROUND

Fever is strongly associated with poor outcome after traumatic brain injury (TBI). We hypothesized that early fever is a direct result of brain injury and thus would be more common in TBI than in patients without brain injury and associated with inflammation.

METHODS

We prospectively enrolled patients with major trauma with and without TBI from a busy Level I trauma center intensive care unit (ICU). Patients were assigned to one of four groups based on their presenting Head Abbreviated Injury Severity Scale scores: multiple injuries: head Abbreviated Injury Scale (AIS) score greater than 2, one other region greater than 2; isolated head: head AIS score greater than 2, all other regions less than 3; isolated body: one region greater than 2, excluding head/face; minor injury: no region with AIS greater than 2. Early fever was defined as at least one recorded temperature greater than 38.3°C in the first 48 hours after admission. Outcome measures included neurologic deterioration, length of stay in the ICU, hospital mortality, discharge Glasgow Outcome Scale-Extended, and plasma levels of seven key cytokines at admission and 24 hours (exploratory).

RESULTS

Two hundred sixty-eight patients were enrolled, including subjects with multiple injuries (n = 59), isolated head (n = 97), isolated body (n = 100), and minor trauma (n = 12). The incidence of fever was similar in all groups irrespective of injury (11-24%). In all groups, there was a significant association between the presence of early fever and death in the hospital (6-18% vs. 0-3%), as well as longer median ICU stays (3-7 days vs. 2-3 days). Fever was significantly associated with elevated IL-6 at admission (50.7 pg/dL vs. 16.9 pg/dL, p = 0.0067) and at 24 hours (83.1 pg/dL vs. 17.1 pg/dL, p = 0.0025) in the isolated head injury group.

CONCLUSION

Contrary to our hypothesis, early fever was not more common in patients with brain injury, though fever was associated with longer ICU stays and death in all groups. Additionally, fever was associated with elevated IL-6 levels in isolated head injury.

LEVEL OF EVIDENCE

Prognostic and Epidemiological study, level III.

Elucidating Pro-Inflammatory Cytokine Responses after Traumatic Brain Injury in a Human Stem Cell Model

Cytokine mediated inflammation likely plays an important role in secondary pathology after traumatic brain injury (TBI). The aim of this study was to elucidate secondary cytokine responses in an in vitro enriched (>80%) human stem cell-derived neuronal model. We exposed neuronal cultures to pre-determined and clinically relevant pathophysiological levels of tumor necrosis factor-α (TNF), interleukin-6 (IL-6) and interleukin-1β (IL-1β), shown to be present in the inflammatory aftermath of TBI. Data from this reductionist human model were then compared with our in vivo data. Human embryonic stem cell (hESC)-derived neurons were exposed to recombinant TNF (1–10,000 pg/mL), IL-1β (1–10,000 pg/mL), and IL-6 (0.1–1000 ng/mL). After 1, 24, and 72 h, culture supernatant was sampled and analyzed using a human cytokine/chemokine 42-plex Milliplex kit on the Luminex platform. The culture secretome revealed both a dose- and/or time-dependent release of cytokines. The IL-6 and TNF exposure each resulted in significantly increased levels of >10 cytokines over time, while IL-1β increased the level of C-X-C motif chemokine 10 (CXCL10/IP10) alone. Importantly, these patterns are consistent with our in vivo (human) TBI data, thus validating our human stem cell-derived neuronal platform as a clinically useful reductionist model. Our data cumulatively suggest that IL-6 and TNF have direct actions, while the action of IL-1β on human neurons likely occurs indirectly through inflammatory cells. The hESC-derived neurons provide a valuable platform to model cytokine mediated inflammation and can provide important insights into the mechanisms of neuroinflammation after TBI.

Naringin Reverses Neurobehavioral and Biochemical Alterations in Intracerebroventricular Collagenase-Induced Intracerebral Hemorrhage in Rats

Intracerebral hemorrhage (ICH) contributes to 10-15% of all strokes and is a high risk factor for morbidity and mortality as compared to other subtypes of stroke, that is, cerebral ischemia and subarachnoid hemorrhage. Oxidative stress (OS)-induced neuroinflammation and neuronal cell death contribute towards the hallmarks of ICH. Spared antioxidant levels, increased inflammatory cytokines and free radicals in ICH lead to neuronal death and exaggerate the hallmarks of ICH. Intracerebroventricular (ICV) collagenase (COL-induced neuronal cell damage and cognitive deficits form a widely recognized experimental model for ICH. Naringin (NGN), a natural antioxidant bioflavonoid, has shown potent neuroprotective effects in different neurodegenerative diseases. However, its potential is least explored in pathological conditions, such as hemorrhagic stroke. This study is aimed at exploring the protective effects of NGN against ICV-COL induced behavioral, neurological and memory deficits in rats. ICV-ICH was induced by single, unilateral intrastriatal injection of COL (1 IU in 2 µL, ICV) over 10 min. From 2nd day onwards, NGN was administered in three different doses (10, 20, and 40 mg/kg; p.o.). Animals were subjected to a battery of behavioral tests to assess behavioral changes, including neurological scoring tests (cylinder test, spontaneous motility, righting reflex, horizontal bar test, forelimb flexion), actophotometer, rotarod, Randall Selitto and von Frey. Poststroke depression and memory deficits were estimated using forced swim test and Morris water maze test, respectively. Poststroke depression, neurological and cognitive deficits were mitigated dose dependently by NGN administration. NGN administration also attenuated the nitro-OS and restored tumor necrosis factor-α and endogenous antioxidant levels. Our research demonstrates that NGN has a protective effect against ICH-induced neurocognitive deficits, along with mitigation of oxido-nitrosative and inflammatory stress.

Effects of immunonutrition on biomarkers in traumatic brain injury patients in Malaysia: a prospective randomized controlled trial

Background

Head injury is one of the top three diagnosis leading to intensive care unit (ICU) admission in Malaysia. There has been growing interest in using immunonutrition as a mode of modulating the inflammatory response to injury or infection with the aim of improving clinical outcome. The aim of the present study was to evaluate the effect of an immunonutrition on biomarkers (IL-6, glutathione, CRP, total protein and albumin) in traumatic brain injury patients.

Methods

Thirty six patients with head injury admitted to neurosurgical ICU in University Malaya Medical Centre were recruited for this study, over a 6-month period from July 2014 to January 2015. Patients were randomized to receive either an immunonutrition (Group A) or a standard (Group B) enteral feed. Levels of biomarkers were measured at day 1, 5 and 7 of enteral feeding.

Results

Patients in Group A showed significant reduction of IL-6 at day 5 (p < 0.001) with concurrent rise in glutathione levels (p = 0.049). Patients in Group A also demonstrated a significant increase of total protein level at the end of the study (day 7).

Conclusion

These findings indicate the potential of immunonutrition reducing cytokines and increasing antioxidant indices in patients with TBI. However, further studies incorporating patient outcomes are needed to determine its overall clinical benefits.

Trial registration

National Medical Research Register (NMRR) ID: 14–1430-23,171. ClinicalTrials.gov identifier: NCT03166449.

Role of Interleukin-10 in Acute Brain Injuries

Interleukin-10 (IL-10) is an important anti-inflammatory cytokine expressed in response to brain injury, where it facilitates the resolution of inflammatory cascades, which if prolonged causes secondary brain damage. Here, we comprehensively review the current knowledge regarding the role of IL-10 in modulating outcomes following acute brain injury, including traumatic brain injury (TBI) and the various stroke subtypes. The vascular endothelium is closely tied to the pathophysiology of these neurological disorders and research has demonstrated clear vascular endothelial protective properties for IL-10. In vitro and in vivo models of ischemic stroke have convincingly directly and indirectly shown IL-10-mediated neuroprotection; although clinically, the role of IL-10 in predicting risk and outcomes is less clear. Comparatively, conclusive studies investigating the contribution of IL-10 in subarachnoid hemorrhage are lacking. Weak indirect evidence supporting the protective role of IL-10 in preclinical models of intracerebral hemorrhage exists; however, in the limited number of clinical studies, higher IL-10 levels seen post-ictus have been associated with worse outcomes. Similarly, preclinical TBI models have suggested a neuroprotective role for IL-10; although, controversy exists among the several clinical studies. In summary, while IL-10 is consistently elevated following acute brain injury, the effect of IL-10 appears to be pathology dependent, and preclinical and clinical studies often paradoxically yield opposite results. The pronounced and potent effects of IL-10 in the resolution of inflammation and inconsistency in the literature regarding the contribution of IL-10 in the setting of acute brain injury warrant further rigorously controlled and targeted investigation.

Characterizing the relationship between systemic inflammatory response syndrome and early cardiac dysfunction in traumatic brain injury

Systolic dysfunction was recently described following traumatic brain injury (TBI), and systemic inflammation may be a contributing mechanism. Our aims were to 1) examine the association between the early systemic inflammatory response syndrome (SIRS) and systolic cardiac dysfunction following TBI, and 2) describe the longitudinal change in SIRS criteria, cardiac function, and hemodynamic parameters during the first week of hospitalization. We used a secondary analysis of a prospective cohort study examining cardiac function (with transthoracic echocardiography on the first day and serially over the first week of hospitalization) in 32 moderate-severe isolated TBI patients, and quantified the admission and daily SIRS response to injury. We determined the association of admission SIRS and systolic dysfunction following TBI. Admission SIRS was present in 7 (21%) patients and was associated with systolic dysfunction on multivariable analysis (relative risk 4.01; 95% 1.16-13.79, p = .028). Both SIRS criteria and systolic cardiac function improved over the first week of hospitalization. In conclusion, early SIRS is common among patients with moderate-severe TBI, and the presence of SIRS criteria on admission is associated with systolic cardiac dysfunction following TBI.

Cytokine cascades induced by mechanical trauma injury alter voltage-gated sodium channel activity in intact cortical neurons

BACKGROUND

Traumatic brain injury (TBI) triggers both immediate (primary) and long-term (secondary) tissue damages. Secondary damages can last from hours to days or even a lifetime. Secondary damages implicate several mechanisms, including influence of inflammatory mediators, mainly cytokines, on excitability of ion channels. However, studies should further explore the effects of inflammatory cytokines on voltage-gated sodium channels (VGSCs) and excitability in distal intact neurons.

METHODS

Mixed cultures of mouse cortical astrocytes and neurons were subjected to mechanical injury (trauma) to mimic TBI in vitro. Expression of various cytokines in these cultures were measured by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. A trauma-conditioned medium with or without brain-derived neurotrophic factor (BDNF) was added to mouse primary cortical neurons for 6 and 24 h to mimic combined effects of multiple inflammatory cytokines on VGSCs. Spike behaviors of distal intact neurons were examined by whole-cell patch-clamp recordings.

RESULTS

Mechanical injury in mixed cortical neuron-astrocyte cultures significantly increased expression levels of multiple cytokines, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α, monocyte chemoattractant protein-1, chemokine (C-C motif) ligand-5, IL-10, and transforming growth factor-β1, at 6 and 24 h after injury. Incubation in trauma-conditioned medium increased functional VGSCs in neuronal membranes and Na⁺ currents. Enhanced VGSCs were almost completely abolished by BDNF, and reinforcement of Na⁺ currents was also reduced in a dose-dependent manner. BDNF (30 ng/mL) also significantly reversed reduced neuronal cell viability, which was induced by medium conditioned at 6 h. At 6 and 24 h, trauma-conditioned medium significantly increased spike frequency but not spike threshold.

CONCLUSIONS

In TBI, the combined effect of inflammatory cytokines is directly involved in VGSC, Na⁺ current, and excitability dysfunction in distal intact neurons. BDNF may partly exert neuroprotective effects by maintaining balance of VGSC function in distal intact neurons.

Pathological vascular and inflammatory biomarkers of acute- and chronic-phase traumatic brain injury

Given the demand for developing objective methods for characterizing traumatic brain injury (TBI), research dedicated to evaluating putative biomarkers has burgeoned over the past decade. Since it is critical to elucidate the underlying pathological processes that underlie the higher diverse outcomes that follow neurotrauma, considerable efforts have been aimed at identifying biomarkers of both the acute- and chronic-phase TBI. Such information is not only critical for helping to elucidate the pathological changes that lead to poor long-term outcomes following TBI but it may also assist in the identification of possible prevention and interventions for individuals who sustain head trauma. In the current review, we discuss the potential role of vascular dysfunction and chronic inflammation in both acute- and chronic-phase TBI, and we also highlight existing studies that have investigated inflammation biomarkers associated with poorer injury outcome.

Complications in Aneurysmal Subarachnoid Hemorrhage Patients With and Without Subdural Electrode Strip for Electrocorticography

PURPOSE

Patients with aneurysmal subarachnoid hemorrhage (aSAH) frequently develop secondary noninfectious and infectious complications with an important impact on clinical course and outcome. In this study, we report on the rate of typical extracranial and intracranial complications in 30 prospectively enrolled patients with severe aSAH who received a linear subdural recording strip for continuous electrocorticography to detect ictal epileptiform events and spreading depolarizations.

METHODS

The group was compared with 30 retrospectively included patients with aSAH who had not received a subdural recording strip, but were treated during the same period. The control group was matched according to an aSAH grading system, sex, and establishment of external ventricular drainage, but could not be matched according to aneurysm treatment and focal brain lesions such as initial intracerebral hemorrhages.

RESULTS

No evidence was found that procedures of the electrocorticography study led to clinically relevant complications. In particular, the subdural strip did not lead to local damage of brain tissue or any increased rate of meningitis/ventriculitis. The median score on the modified Rankin Scale on day 15 was the same in both groups. Minor differences between both groups are explained by the limitations in the study design.

CONCLUSIONS

Our study suggests that neuromonitoring with a subdural recording strip for up to 15 days can be safely performed in patients with aSAH.

Emerging Roles for the Immune System in Traumatic Brain Injury

Traumatic brain injury (TBI) affects an ever-growing population of all ages with long-term consequences on health and cognition. Many of the issues that TBI patients face are thought to be mediated by the immune system. Primary brain damage that occurs at the time of injury can be exacerbated and prolonged for months or even years by chronic inflammatory processes, which can ultimately lead to secondary cell death, neurodegeneration, and long-lasting neurological impairment. Researchers have turned to rodent models of TBI in order to understand how inflammatory cells and immunological signaling regulate the post-injury response and recovery mechanisms. In addition, the development of numerous methods to manipulate genes involved in inflammation has recently expanded the possibilities of investigating the immune response in TBI models. As results from these studies accumulate, scientists have started to link cells and signaling pathways to pro- and anti-inflammatory processes that may contribute beneficial or detrimental effects to the injured brain. Moreover, emerging data suggest that targeting aspects of the immune response may offer promising strategies to treat TBI. This review will cover insights gained from studies that approach TBI research from an immunological perspective and will summarize our current understanding of the involvement of specific immune cell types and cytokines in TBI pathogenesis.

Inflammatory cytokine and chemokine profiles are associated with patient outcome and the hyperadrenergic state following acute brain injury

Background

Traumatic brain injury (TBI) elicits intense sympathetic nervous system (SNS) activation with profuse catecholamine secretion. The resultant hyperadrenergic state is linked to immunomodulation both within the brain and systemically. Dysregulated inflammation post-TBI exacerbates secondary brain injury and contributes to unfavorable patient outcomes including death. The aim of this study was to characterize the early dynamic profile of circulating inflammatory cytokines/chemokines in patients admitted for moderate-to-severe TBI, to examine interrelationships between these mediators and catecholamines, as well as clinical indices of injury severity and neurological outcome.

Methods

Blood was sampled from 166 isolated TBI patients (aged 45 ± 20.3 years; 74.7 % male) on admission, 6-, 12-, and 24-h post-injury and from healthy controls (N = 21). Plasma cytokine [interleukin (IL)-1β, -2, -4, -5, -10, -12p70, -13, tumor necrosis factor (TNF)-α, interferon (IFN)-γ] and chemokine [IL-8, eotaxin, eotaxin-3, IFN-γ-induced protein (IP)-10, monocyte chemoattractant protein (MCP)-1, -4, macrophage-derived chemokine (MDC), macrophage inflammatory protein (MIP)-1β, thymus activation regulated chemokine (TARC)] concentrations were analyzed using high-sensitivity electrochemiluminescence multiplex immunoassays. Plasma catecholamines [epinephrine (Epi), norepinephrine (NE)] were measured by immunoassay. Neurological outcome at 6 months was assessed using the extended Glasgow outcome scale (GOSE) dichotomized as good (>4) or poor (≤4) outcomes.

Results

Patients showed altered levels of IL-10 and all chemokines assayed relative to controls. Significant differences in a number of markers were evident between moderate and severe TBI cohorts. Elevated IL-8, IL-10, and TNF-α, as well as alterations in 8 of 9 chemokines, were associated with poor outcome at 6 months. Notably, a positive association was found between Epi and IL-1β, IL-10, Eotaxin, IL-8, and MCP-1. NE was positively associated with IL-1β, IL-10, TNF-α, eotaxin, IL-8, IP-10, and MCP-1.

Conclusions

Our results provide further evidence that exaggerated SNS activation acutely after isolated TBI in humans may contribute to harmful peripheral inflammatory cytokine/chemokine dysregulation. These findings are consistent with a potentially beneficial role for therapies aimed at modulating the inflammatory response and hyperadrenergic state acutely post-injury.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0500-3) contains supplementary material, which is available to authorized users.

The effect of brain injury on the inflammatory response following severe trauma

INTRODUCTION

The inflammatory response is an important part of the pathophysiology of severe injury and, in particular, of severe traumatic brain injury (TBI). This study evaluates the inflammatory course following major trauma and focuses on the effect of severe TBI on inflammatory markers.

MATERIAL AND METHODS

This was a retrospective analysis of prospectively collected data in 123 severely injured (ISS ≥16) trauma patients. The study cohort was divided into patients with isolated TBI (Head AIS ≥3, all other AIS <3), polytraumatized patients with severe TBI (Head AIS ≥3; AIS of other body area ≥3; Polytrauma+TBI) and polytraumatized patients without TBI (Head AIS <3; Polytrauma). Levels of inflammatory markers (Interleukin-6 [IL-6], C-reactive Protein [CRP], leukocytes) measured upon arrival and through hospital days 1-3 were compared between the groups.

RESULTS

On admission and through hospital day 3, IL-6 levels were significantly different between the 3 groups (admission: isolated TBI vs. Polytrauma+TBI vs. Polytrauma; 94±16 vs. 149±20 vs. 245±50pg/mL; p<0.05). Interleukin-6 levels peaked on hospital day 1 and declined thereafter. C-reactive protein and leukocyte counts were not significantly different between the cohorts on arrival and peaked on hospital day 2 and 1, respectively. In patients with severe TBI, admission IL-6 levels significantly predicted the development of septic complications (ROC analysis, AUC: 0.88, p=0.001, 95% CI: 0.79-0.97) and multiple organ dysfunction (ROC analysis, AUC: 0.83, p=0.001, 95% CI: 0.69-0.96).

CONCLUSION

Severe TBI reduced the inflammatory response following trauma. Significant correlations between admission IL-6 values and the development of MOF, sepsis and the neurological outcome were found in patients with TBI.

Neuroprotective effect of interleukin-6 regulation of voltage-gated Na(+) channels of cortical neurons is time- and dose-dependent

Interleukin-6 has been shown to be involved in nerve injury and nerve regeneration, but the effects of long-term administration of high concentrations of interleukin-6 on neurons in the central nervous system is poorly understood. This study investigated the effects of 24 hour exposure of interleukin-6 on cortical neurons at various concentrations (0.1, 1, 5 and 10 ng/mL) and the effects of 10 ng/mL interleukin-6 exposure to cortical neurons for various durations (2, 4, 8, 24 and 48 hours) by studying voltage-gated Na(+) channels using a patch-clamp technique. Voltage-clamp recording results demonstrated that interleukin-6 suppressed Na(+) currents through its receptor in a time- and dose-dependent manner, but did not alter voltage-dependent activation and inactivation. Current-clamp recording results were consistent with voltage-clamp recording results. Interleukin-6 reduced the action potential amplitude of cortical neurons, but did not change the action potential threshold. The regulation of voltage-gated Na(+) channels in rat cortical neurons by interleukin-6 is time- and dose-dependent.

Clinical evidence of inflammation driving secondary brain injury: a systematic review

BACKGROUND

Despite advances in both prevention and treatment, traumatic brain injury (TBI) remains one of the most burdensome diseases; 2% of the US population currently lives with disabilities resulting from TBI. Recent advances in the understanding of inflammation and its impact on the pathophysiology of trauma have increased the interest in inflammation as a possible mediator in TBI outcome.

OBJECTIVES

The goal of this systematic review is to address the question: "What is the evidence in humans that inflammation is linked to secondary brain injury?" As the experimental evidence has been well described elsewhere, this review will focus on the clinical evidence for inflammation as a mechanism of secondary brain injury.

DATA SOURCES

Medline database (1996-Week 1 June 2014), Pubmed and Google Scholar databases were queried for relevant studies.

STUDY ELIGIBILITY CRITERIA

Studies were eligible if participants were adults and/or children who sustained moderate or severe TBI in the acute phase of injury, published in English. Studies published in the last decade (since 2004) were preferentially included. Trials could be observational or interventional in nature.

APPRAISAL AND SYNTHESIS METHODS

To address the quality of the studies retrieved, we applied the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria to assess the limitations of the included studies.

RESULTS

Trauma initiates local central nervous system as well as systemic immune activation. Numerous observational studies describe elevation of pro-inflammatory cytokines that are associated with important clinical variables including neurologic outcome and mortality. A small number of clinical trials have included immunomodulating strategies, but no intervention to date has proven effective in improving outcomes after TBI.

LIMITATIONS

Inclusion of studies not initially retrieved by the search terms may have biased our results. Additionally, some reports may have been inadvertently excluded due to use of non-search term key words. Conclusions and Implications of Key Findings Clinical evidence of inflammation causing secondary brain injury in humans is gaining momentum. While inflammation is certainly present, it is not clear from the literature at what juncture inflammation becomes maladaptive, promoting secondary injury rather than facilitating repairand identifying patients with maladaptive inflammation (neuro-inflammation, systemic, or both) after TBI remains elusive. Direct agonism/antagonism represents an exciting target for future study.

LEVEL OF EVIDENCE

Systematic review, level III.