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

Hspb1 and Lgals3 in spinal neurons are closely associated with autophagy following excitotoxicity based on machine learning algorithms

Excitotoxicity represents the primary cause of neuronal death following spinal cord injury (SCI). While autophagy plays a critical and intricate role in SCI, the specific mechanism underlying the relationship between excitotoxicity and autophagy in SCI has been largely overlooked. In this study, we isolated primary spinal cord neurons from neonatal rats and induced excitotoxic neuronal injury by high concentrations of glutamic acid, mimicking an excitotoxic injury model. Subsequently, we performed transcriptome sequencing. Leveraging machine learning algorithms, including weighted correlation network analysis (WGCNA), random forest analysis (RF), and least absolute shrinkage and selection operator analysis (LASSO), we conducted a comprehensive investigation into key genes associated with spinal cord neuron injury. We also utilized protein-protein interaction network (PPI) analysis to identify pivotal proteins regulating key gene expression and analyzed key genes from public datasets (GSE2599, GSE20907, GSE45006, and GSE174549). Our findings revealed that six genes-Anxa2, S100a10, Ccng1, Timp1, Hspb1, and Lgals3-were significantly upregulated not only in vitro in neurons subjected to excitotoxic injury but also in rats with subacute SCI. Furthermore, Hspb1 and Lgals3 were closely linked to neuronal autophagy induced by excitotoxicity. Our findings contribute to a better understanding of excitotoxicity and autophagy, offering potential targets and a theoretical foundation for SCI diagnosis and treatment.

Fecal Microbiota Transplantation-Mediated Ghrelin Restoration Improves Neurological Functions After Traumatic Brain Injury: Evidence from 16S rRNA Sequencing and In Vivo Studies

This study aimed to investigate how gut microbiota dysbiosis impacts the repair of the blood-brain barrier and neurological deficits following traumatic brain injury (TBI). Through 16S rRNA sequencing analysis, we compared the gut microbiota of TBI rats and normal controls, discovering significant differences in abundance, species composition, and ecological function, potentially linked to Ghrelin-mediated brain-gut axis functionality. Further, in vivo experiments showed that fecal microbiota transplantation or Ghrelin injection could block the intracerebral TNF signaling pathway, enhance GLP-1 expression, significantly reduce brain edema post-TBI, promote the repair of the blood-brain barrier, and improve neurological deficits. However, the TNF signaling pathway activation could reverse these beneficial effects. In summary, our research suggests that by restoring the balance of gut microbiota, the levels of Ghrelin can be elevated, leading to the blockade of intracerebral TNF signaling pathway and enhanced GLP-1 expression, thereby mitigating post-TBI blood-brain barrier disruption and neurological injuries.

The Role of Neuroinflammatory Mediators in the Pathogenesis of Traumatic Brain Injury: A Narrative Review

Traumatic brain injury (TBI) is a debilitating acquired neurological disorder that afflicts nearly 74 million people worldwide annually. TBI has been classified as more than just a single insult because of its associated risk toward various long-term neurological and neurodegenerative disorders. This risk may be triggered by a series of postinjury secondary molecular and cellular pathology, which may be dependent on the severity of the TBI. Among the secondary injury mechanisms, neuroinflammation may be the most crucial as it may exacerbate brain damage and lead to fatal consequences when prolonged. This Review aimed to elucidate the influence of neuroinflammatory mediators on the TBI functional and pathological outcomes, particularly focusing on inflammatory cytokines which were associated with neuronal dysfunctions in the acute and chronic stages of TBI. These cytokines include interleukins (IL) such as IL-1(beta)β, IL-4, IL-6, IL8, IL-10, IL-18, IL-33 and tumor necrosis factor alpha (TNF-α), which have been extensively studied. Apart from these, IL-2, interferon gamma (IFN-γ), and transforming growth factor-beta (TGF-β) may also play a significant role in the pathogenesis of TBI. These neuroinflammatory mediators may trigger a series of pathological events such as cell death, microglial suppression, and increased catecholaminergic activity. Interestingly, in the acute phase of TBI, most of these mediators may also play a neuroprotective role by displaying anti-inflammatory properties, which may convert to a pro-inflammatory action in the chronic stages post TBI. Early identification and treatment of these mediators may help the development of more effective treatment options for TBI.

Subacute cytokine changes after a traumatic brain injury predict chronic brain microstructural alterations on advanced diffusion imaging in the male rat

INTRODUCTION

The process of neuroinflammation occurring after traumatic brain injury (TBI) has received significant attention as a potential prognostic indicator and interventional target to improve patients' outcomes. Indeed, many of the secondary consequences of TBI have been attributed to neuroinflammation and peripheral inflammatory changes. However, inflammatory biomarkers in blood have not yet emerged as a clinical tool for diagnosis of TBI and predicting outcome. The controlled cortical impact model of TBI in the rodent gives reliable readouts of the dynamics of post-TBI neuroinflammation. We now extend this model to include a panel of plasma cytokine biomarkers measured at different time points post-injury, to test the hypothesis that these markers can predict brain microstructural outcome as quantified by advanced diffusion-weighted magnetic resonance imaging (MRI).

METHODS

Fourteen 8-10-week-old male rats were randomly assigned to sham surgery (n = 6) and TBI (n = 8) treatment with a single moderate-severe controlled cortical impact. We collected blood samples for cytokine analysis at days 1, 3, 7, and 60 post-surgery, and carried out standard structural and advanced diffusion-weighted MRI at day 60. We then utilized principal component regression to build an equation predicting different aspects of microstructural changes from the plasma inflammatory marker concentrations measured at different time points.

RESULTS

The TBI group had elevated plasma levels of IL-1β and several neuroprotective cytokines and chemokines (IL-7, CCL3, and GM-CSF) compared to the sham group from days 3 to 60 post-injury. The plasma marker panels obtained at day 7 were significantly associated with the outcome at day 60 of the trans-hemispheric cortical map transfer process that is a frequent finding in unilateral TBI models.

DISCUSSION

These results confirm and extend prior studies showing that day 7 post-injury is a critical temporal window for the reorganisation process following TBI. High plasma level of IL-1β and low plasma levels of the neuroprotective IL-7, CCL3, and GM-CSF of TBI animals at day 60 were associated with greater TBI pathology.

Multimodal brain monitoring following traumatic brain injury: A primer for intensive care practitioners

Traumatic brain injury (TBI) is common and potentially devastating. Traditional examination-based patient monitoring following TBI may be inadequate for frontline clinicians to reduce secondary brain injury through individualized therapy. Multimodal neurologic monitoring (MMM) offers great potential for detecting early injury and improving outcomes. By assessing cerebral oxygenation, autoregulation and metabolism, clinicians may be able to understand neurophysiology during acute brain injury, and offer therapies better suited to each patient and each stage of injury. Hence, we offer this primer on brain tissue oxygen monitoring, pressure reactivity index monitoring and cerebral microdialysis. This narrative review serves as an introductory guide to the latest clinically-relevant evidence regarding key neuromonitoring techniques.

Clinical Correlates Identify ProBDNF and Thrombo-Inflammatory Markers as Key Predictors of Circulating p75NTR Extracellular Domain Levels in Older Adults

The p75^NTR receptor binds all neurotrophins and is mostly known for its role in neuronal survival and apoptosis. Recently, the extracellular domain (ECD) of p75^NTR has been reported in plasma, its levels being dysregulated in numerous neurological diseases. However, the factors associated with p75^NTR ECD levels remain unknown. We investigated clinical correlates of plasma p75^NTR ECD levels in older adults without clinically manifested neurological disorders. Circulating p75^NTR levels were measured by enzyme-linked immunosorbent assay in plasma obtained from participants in the BEL-AGE cohort (n = 1,280). Determinants of plasma p75^NTR ECD levels were explored using linear and non-linear statistical models. Plasma p75^NTR ECD levels were higher in male participants; were positively correlated with circulating concentrations of pro-brain-derived neurotrophic factor, and inflammatory markers interleukin-6 and CD40 Ligand; and were negatively correlated with the platelet activation marker P-selectin. While most individuals had p75^NTR levels ranging from 43 to 358 pg/ml, high p75^NTR levels reaching up to 9,000 pg/ml were detectable in a subgroup representing 15% of the individuals studied. In this cohort of older adults without clinically manifested neurological disorders, there was no association between plasma p75^NTR ECD levels and cognitive performance, as assessed by the Montreal Cognitive Assessment score. The physiological relevance of high p75^NTR ECD levels in plasma warrants further investigation. Further research assessing the source of circulating p75^NTR is needed for a deeper understanding of the direction of effect, and to investigate whether high p75^NTR ECD levels are predictive biomarkers or consequences of neuropathology.

Association of Early Multiple Organ Dysfunction With Clinical and Functional Outcomes Over the Year Following Traumatic Brain Injury: A Transforming Research and Clinical Knowledge in Traumatic Brain Injury Study

OBJECTIVES

Traumatic brain injury is a leading cause of death and disability in the United States. While the impact of early multiple organ dysfunction syndrome has been studied in many critical care paradigms, the clinical impact of early multiple organ dysfunction syndrome in traumatic brain injury is poorly understood. We examined the incidence and impact of early multiple organ dysfunction syndrome on clinical, functional, and disability outcomes over the year following traumatic brain injury.

DESIGN

Retrospective cohort study.

SETTING

Patients enrolled in the Transforming Clinical Research and Knowledge in Traumatic Brain Injury study, an 18-center prospective cohort study of traumatic brain injury patients evaluated in participating level 1 trauma centers.

SUBJECTS

Adult (age > 17 yr) patients with moderate-severe traumatic brain injury (Glasgow Coma Scale < 13). We excluded patients with major extracranial injury (Abbreviated Injury Scale score ≥ 3).

INTERVENTIONS

Development of early multiple organ dysfunction syndrome, defined as a maximum modified Sequential Organ Failure Assessment score greater than 7 during the initial 72 hours following admission.

MEASUREMENTS AND MAIN RESULTS

The main outcomes were: hospital mortality, length of stay, 6-month functional and disability domains (Glasgow Outcome Scale-Extended and Disability Rating Scale), and 1-year mortality. Secondary outcomes included: ICU length of stay, 3-month Glasgow Outcome Scale-Extended, 3-month Disability Rating Scale, 1-year Glasgow Outcome Scale-Extended, and 1-year Disability Rating Scale. We examined 373 subjects with moderate-severe traumatic brain injury. The mean (sd) Glasgow Coma Scale in the emergency department was 5.8 (3.2), with 280 subjects (75%) classified as severe traumatic brain injury (Glasgow Coma Scale 3-8). Among subjects with moderate-severe traumatic brain injury, 252 (68%) developed early multiple organ dysfunction syndrome. Subjects that developed early multiple organ dysfunction syndrome had a 75% decreased odds of a favorable outcome (Glasgow Outcome Scale-Extended 5-8) at 6 months (adjusted odds ratio, 0.25; 95% CI, 0.12-0.51) and increased disability (higher Disability Rating Scale score) at 6 months (adjusted mean difference, 2.04; 95% CI, 0.92-3.17). Subjects that developed early multiple organ dysfunction syndrome experienced an increased hospital length of stay (adjusted mean difference, 11.4 d; 95% CI, 7.1-15.8), with a nonsignificantly decreased survival to hospital discharge (odds ratio, 0.47; 95% CI, 0.18-1.2).

CONCLUSIONS

Early multiple organ dysfunction following moderate-severe traumatic brain injury is common and independently impacts multiple domains (mortality, function, and disability) over the year following injury. Further research is necessary to understand underlying mechanisms, improve early recognition, and optimize management strategies.

Neurokinin-1 Receptor as a potential drug target for COVID-19 treatment

Novel Coronavirus infection (COVID-19) has become a pandemic in these days. It is an acute respiratory and infectious disease with no known etiology and treatment. It is continuously causing losses of precious lives and economy at a global scale on daily basis. It is the need of the hour to find more treatment strategies by either developing a drug or to boost the immune system. This opinion article aims to provide Substance P (SP) as a possible cause of the initiation of cytokine storm developed in COVID-19 infection and to suggest Neurokinin-1 Receptor (NK-1R) antagonist, Aprepitant, as a drug to be used for its treatment. This perspective will provide directions to the Biomedical scientists to explore SP and NK-1R and prepare a drug to alleviate the symptoms and cure the disease. It is very important to work on this perspective at earliest to reach to some conclusion regarding the therapeutic intervention. Clinical studies may also be conducted if proven successful. SP is a neurotransmitter and neuromodulator, released from the trigeminal nerve of brainstem as a result of nociception. It is directly related to the respiratory illness as in COVID-19 infection. It is responsible for the increased inflammation and the signature symptoms associated with this disease. It is the main switch that needs to be switched off by administering Aprepitant along with glucocorticosteroid, dexamethasone.

Neuroinflammation and Precision Medicine in Pediatric Neurocritical Care: Multi-Modal Monitoring of Immunometabolic Dysfunction

The understanding of molecular biology in neurocritical care (NCC) is expanding rapidly and recognizing the important contribution of neuroinflammation, specifically changes in immunometabolism, towards pathological disease processes encountered across all illnesses in the NCC. Additionally, the importance of individualized inflammatory responses has been emphasized, acknowledging that not all individuals have the same mechanisms contributing towards their presentation. By understanding cellular processes that drive disease, we can make better personalized therapy decisions to improve patient outcomes. While the understanding of these cellular processes is evolving, the ability to measure such cellular responses at bedside to make acute care decisions is lacking. In this overview, we review cellular mechanisms involved in pathological neuroinflammation with a focus on immunometabolic dysfunction and review non-invasive bedside tools that have the potential to measure indirect and direct markers of shifts in cellular metabolism related to neuroinflammation. These tools include near-infrared spectroscopy, transcranial doppler, elastography, electroencephalography, magnetic resonance imaging and spectroscopy, and cytokine analysis. Additionally, we review the importance of genetic testing in providing information about unique metabolic profiles to guide individualized interpretation of bedside data. Together in tandem, these modalities have the potential to provide real time information and guide more informed treatment decisions.

Biomarkers in traumatic brain injury: new concepts

Traumatic brain injury is a multifaceted condition that encompasses a spectrum of injuries: contusions, axonal injuries in specific brain regions, edema, and hemorrhage. Brain injury determines a broad clinical and disability spectrum due to the implication of various cellular pathways, genetic phenotypes, and environmental factors. It is challenging to predict patient outcomes, to appropriately evaluate the patients, to determine a suitable treatment strategy and rehabilitation program, and to communicate with patient relatives. Biomarkers detected from body fluids are potential evaluation tools for traumatic brain injury patients. These may serve as internal indicators of cerebral damage, delivering valuable information about the dynamic cellular, biochemical, and molecular environments. The diagnostic and prognostic value of biomarkers tested both in animal models of traumatic brain injury is still under question, despite a considerable scientific literature. Recent publications emphasize that a more realistic approach involves combining multiple types of biomarkers with other investigative tools (imaging, outcome scales, and genetic polymorphisms). Additionally, there is increasing interest in the use of biomarkers as tools for treatment monitoring and as surrogate outcome variables to facilitate the design of distinct randomized controlled trials. This review highlights the latest available evidence regarding biomarkers in adults after traumatic brain injury and discusses new approaches in the evaluation of this patient group.

Systemic Inflammation Persists the First Year after Mild Traumatic Brain Injury: Results from the Prospective Trondheim Mild Traumatic Brain Injury Study

Innate immune activation has been attributed a key role in traumatic brain injury (TBI) and successive morbidity. In mild TBI (mTBI), however, the extent and persistence of innate immune activation are unknown. We determined plasma cytokine level changes over 12 months after an mTBI in hospitalized and non-hospitalized patients compared with community controls; and examined their associations to injury-related and demographic variables at admission. Prospectively, 207 patients presenting to the emergency department (ED) or general practitioner with clinically confirmed mTBI and 82 matched community controls were included. Plasma samples were obtained at admission, after 2 weeks, 3 months, and 12 months. Cytokine levels were analysed with a 27-plex beads-based immunoassay. Brain magnetic resonance imaging (MRI) was performed on all participants. Twelve cytokines were reliably detected. Plasma levels of interferon gamma (IFN-γ), interleukin 8 (IL-8), eotaxin, macrophage inflammatory protein-1-beta (MIP-1β), monocyte chemoattractant protein 1 (MCP-1), IL-17A, IL-9, tumor necrosis factor (TNF), and basic fibroblast growth factor (FGF-basic) were significantly increased at all time-points in patients compared with controls, whereas IFN-γ-inducing protein 10 (IP-10), platelet-derived growth factor (PDGF), and IL-1ra were not. IL-17A and FGF-basic showed significant increases in patients from admission to follow-up at 3 months, and remained increased at 12 months compared with admission. Interestingly, MRI findings were negatively associated with four cytokines: eotaxin, MIP-1β, IL-9, and IP-10, whereas age was positively associated with nine cytokines: IL-8, eotaxin, MIP-1β, MCP-1, IL-17A, IL-9, TNF, FGF-basic, and IL-1ra. TNF was also increased in those with presence of other injuries. In conclusion, mTBI activated the innate immune system consistently and this is the first study to show that several inflammatory cytokines remain increased for up to 1 year post-injury.

Therapeutic Development of Apolipoprotein E Mimetics for Acute Brain Injury: Augmenting Endogenous Responses to Reduce Secondary Injury

Over the last few decades, increasing evidence demonstrates that the neuroinflammatory response is a double-edged sword. Although overly robust inflammatory responses may exacerbate secondary tissue injury, inflammatory processes are ultimately necessary for recovery. Traditional drug discovery often relies on reductionist approaches to isolate and modulate specific intracellular pathways believed to be involved in disease pathology. However, endogenous brain proteins are often pleiotropic in order to regulate neuroinflammation and recovery mechanisms. Thus, a process of "backward translation" aims to harness the adaptive properties of endogenous proteins to promote earlier and greater recovery after acute brain injury. One such endogenous protein is apolipoprotein E (apoE), the primary apolipoprotein produced in the brain. Robust preclinical and clinical evidence demonstrates that endogenous apoE produced within the brain modulates the neuroinflammatory response of the acutely injured brain. Thus, one innovative approach to improve outcomes following acute brain injury is administration of exogenous apoE-mimetic drugs optimized to cross the blood-brain barrier. In particular, one promising apoE mimetic peptide, CN-105, has demonstrated efficacy across a wide variety of preclinical models of brain injury and safety and feasibility in early-phase clinical trials. Preclinical and clinical evidence for apoE's neuroprotective effects and downregulation of neuroinflammatory and the resulting translational therapeutic development strategy for an apoE-based therapeutic are reviewed.

Nonsurviving Patients with Severe Traumatic Brain Injury Have Maintained High Serum sCD40L Levels

BACKGROUND

Soluble cluster of differentiation 40 ligand (sCD40L) is a member of the tumor necrosis factor family with proinflamatory and procoagulant effects. A previous study found higher serum sCD40L levels at day 1 of traumatic brain injury (TBI) in nonsurviving than surviving patients. Thus the objective of this study was to compare serum sCD40L levels during the first week of a severe TBI between surviving and nonsurviving patients and to determine whether it could be used as a mortality predictor biomarker.

METHODS

In this multicenter study severe TBI patients (with Glasgow Coma Scale score <9) with an Injury Severity Score in noncranial item <9 were included. Serum sCD40L concentrations at days 1, 4, and 8 of TBI were determined. We performed receiver operating characteristic analyses to determine the capacity of 30-day TBI mortality prediction by serum sCD40L levels at days 1, 4, and 8 of TBI.

RESULTS

We found that nonsurviving (n = 34) patients in comparison with surviving (n = 90) patients had higher sCD40L levels on days 1 (P < 0.001), 4 (P = 0.004), and 8 (P < 0.001) of TBI. We also found that the areas under curve of serum sCD40L concentrations at days 1, 4, and 8 of TBI to 30-day mortality prediction were 82% (P < 0.001), 72% (P = 0.01) and 83% (P < 0.001), respectively.

CONCLUSIONS

The existence of higher serum sCD40L levels in nonsurviving than surviving patients during the first week of TBI and fact that serum sCD40L levels during the first week of TBI can be used as a mortality predictor biomarker are the new findings of our study.

[Influence of massive blood transfusion and traumatic brain injury on TIMP‑1 and MMP‑9 serum levels in polytraumatized patients]

BACKGROUND

The morbidity and mortality of polytrauma patients are substantially influenced by the extent of the posttraumatic inflammatory reaction. Studies have shown that TIMP‑1 and MMP‑9 play a major role in posttraumatic immune disorder in genome-wide mRNA microarray analyses. Furthermore, both showed differential gene expression profiles depending on the clinical parameters massive blood transfusion and traumatic brain injury.

OBJECTIVE

The aim of this study was to evaluate TIMP‑1 and MMP‑9 serum concentrations in polytraumatized patients depending on the clinical parameters massive blood transfusion and traumatic brain injury in the early posttraumatic phase.

MATERIAL AND METHODS

Polytrauma patients (≥18 years) with an "Injury Severity Score" (ISS) ≥ 16 points were enrolled in this prospective study. Serum levels of TIMP‑1 and MMP‑9 were quantified (at 0 h, 6 h, 12 h, 24 h, 48 h and 72 h) using an enzyme-linked immunosorbent assay (ELISA). Groups were divided according to the clinical parameter massive blood transfusion (≥10 red blood cell units [RBC units] in the first 24-hour posttrauma) and traumatic brain injury (CCT postive [cranial computed tomography]).

RESULTS

Following massive blood transfusion (n = 21; 50 ± 15.7 years; ISS 39 ± 12.8 points) patients showed overall significantly increased TIMP‑1 levels (p = 0.003) and significantly higher TIMP‑1 values after 12-72 h. Traumatic brain injury patients (n = 28; 44 ± 19 years; ISS 42 ± 10 points) showed significantly higher MMP‑9 levels (p = 0.049) in the posttraumatic period.

CONCLUSION

Polytraumatized patients who received massive blood transfusions following major trauma showed significantly higher TIMP‑1 levels than patients who did not receive massive transfusions. This seems to be an expression of a massively excessive inflammatory reaction and therefore represents a substantial factor in the pathogenesis of severe posttraumatic immune dysfunction in this collective. Furthermore, the significant increase in MMP‑9 with accompanying traumatic brain injury reflects the pivotal role of matrix metalloproteinases in the pathophysiology of traumatic brain injury.

Persistently high circulating tissue inhibitor of matrix metalloproteinase-1 levels in non-survivor brain trauma injury patients

PURPOSE

Previously, higher circulating levels of matrix metalloproteinase (MMP)-9 and tissue inhibitor matrix metalloproteinases (TIMP)-1 were reported in the first hours after TBI in blood samples from patients with poor prognosis. Thus, the objectives of this study were to determine whether MMP-9 and TIMP-1 levels during the first week of a severe TBI could be used as biomarker predictive of mortality.

METHODS

We included patients with severe TBI (defined as Glasgow Coma Scale lower than 9), and with Injury Severity Score in non-cranial aspects lower than 9. We determined serum concentrations of MMP-9 and TIMP-1 at days 1, 4 and 8 of TBI.

RESULTS

TIMP-1 concentrations at days 1 (p < .001), 4 (p = .001), and 8 (p = .01) of TBI were higher in non-surviving (n = 34) than in surviving (n = 90) patients. ROC curve analyses showed an area under curve of TIMP-1 concentrations at days 1, 4, and 8 of TBI to predict 30-day mortality of 78% (p < .001), 76% (p < .001) and 71% (p = .02) respectively.

CONCLUSIONS

The most relevant new findings of our study were that TIMP-1 levels during the first week of a severe TBI were higher in non-surviving than in surviving patients and that could be used as biomarker predictive of mortality.