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

C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 pathway as a therapeutic target and regulatory mechanism for spinal cord injury

Spinal cord injury involves non-reversible damage to the central nervous system that is characterized by limited regenerative capacity and secondary inflammatory damage. The expression of the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis exhibits significant differences before and after injury. Recent studies have revealed that the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis is closely associated with secondary inflammatory responses and the recruitment of immune cells following spinal cord injury, suggesting that this axis is a novel target and regulatory control point for treatment. This review comprehensively examines the therapeutic strategies targeting the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis, along with the regenerative and repair mechanisms linking the axis to spinal cord injury. Additionally, we summarize the upstream and downstream inflammatory signaling pathways associated with spinal cord injury and the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis. This review primarily elaborates on therapeutic strategies that target the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis and the latest progress of research on antagonistic drugs, along with the approaches used to exploit new therapeutic targets within the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis and the development of targeted drugs. Nevertheless, there are presently no clinical studies relating to spinal cord injury that are focusing on the C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 axis. This review aims to provide new ideas and therapeutic strategies for the future treatment of spinal cord injury.

The Gut-Brain Axis and Neuroinflammation in Traumatic Brain Injury

Traumatic brain injury (TBI) is a major global disability and mortality cause, with the gut-brain axis playing a crucial role in its pathophysiology. Neuroinflammation, triggered by microglia and astrocytes, contributes to neuronal damage and cognitive impairment. This paper aims to explore the relationship between the gut-brain axis and neuroinflammation in TBI and its potential implications for therapeutic interventions. A comprehensive review of the literature was conducted using PubMed, MEDLINE, and Google Scholar databases. Studies investigating the gut-brain axis, neuroinflammation, and TBI were included. Evidence suggests that TBI disrupts the gut-brain axis, leading to alterations in gut microbiota composition, intestinal permeability, and immune responses. These gut-related changes promote the activation of microglia and astrocytes in the central nervous system, contributing to neuroinflammation and neuronal damage. Conversely, interventions that modulate gut microbiota or reduce intestinal permeability have been shown to attenuate neuroinflammation and improve cognitive outcomes in TBI models. The gut-brain axis plays a significant role in the pathogenesis of neuroinflammation following TBI. Targeting the gut-brain axis through interventions that restore gut homeostasis and reduce intestinal permeability holds promise as a novel therapeutic strategy for mitigating neuroinflammation and improving cognitive function in TBI patients. Further research is needed to elucidate the specific mechanisms involved and to develop effective therapies based on this understanding.

Transforming growth factor-beta 1 enhances discharge activity of cortical neurons

JOURNAL/nrgr/04.03/01300535-202502000-00031/figure1/v/2024-05-28T214302Z/r/image-tiff Transforming growth factor-beta 1 (TGF-β1) has been extensively studied for its pleiotropic effects on central nervous system diseases. The neuroprotective or neurotoxic effects of TGF-β1 in specific brain areas may depend on the pathological process and cell types involved. Voltage-gated sodium channels (VGSCs) are essential ion channels for the generation of action potentials in neurons, and are involved in various neuroexcitation-related diseases. However, the effects of TGF-β1 on the functional properties of VGSCs and firing properties in cortical neurons remain unclear. In this study, we investigated the effects of TGF-β1 on VGSC function and firing properties in primary cortical neurons from mice. We found that TGF-β1 increased VGSC current density in a dose- and time-dependent manner, which was attributable to the upregulation of Nav1.3 expression. Increased VGSC current density and Nav1.3 expression were significantly abolished by preincubation with inhibitors of mitogen-activated protein kinase kinase (PD98059), p38 mitogen-activated protein kinase (SB203580), and Jun NH2-terminal kinase 1/2 inhibitor (SP600125). Interestingly, TGF-β1 significantly increased the firing threshold of action potentials but did not change their firing rate in cortical neurons. These findings suggest that TGF-β1 can increase Nav1.3 expression through activation of the ERK1/2-JNK-MAPK pathway, which leads to a decrease in the firing threshold of action potentials in cortical neurons under pathological conditions. Thus, this contributes to the occurrence and progression of neuroexcitatory-related diseases of the central nervous system.

Astrocytes facilitate gabazine-evoked electrophysiological hyperactivity and distinct biochemical responses in mature neuronal cultures

Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the adult brain that binds to GABA receptors and hyperpolarizes the postsynaptic neuron. Gabazine acts as a competitive antagonist to type A GABA receptors (GABAAR), thereby causing diminished neuronal hyperpolarization and GABAAR-mediated inhibition. However, the biochemical effects and the potential regulatory role of astrocytes in this process remain poorly understood. To address this, we investigated the neuronal responses of gabazine in rat cortical cultures containing varying ratios of neurons and astrocytes. Electrophysiological characterization was performed utilizing microelectrode arrays (MEAs) with topologically controlled microcircuit cultures that enabled control of neuronal network growth. Biochemical analysis of the cultures was performed using traditional dissociated cultures on coverslips. Our study indicates that, upon gabazine stimulation, astrocyte-rich neuronal cultures exhibit elevated electrophysiological activity and tyrosine phosphorylation of tropomyosin receptor kinase B (TrkB; receptor for brain-derived neurotrophic factor), along with distinct cytokine secretion profiles. Notably, neurons lacking proper astrocytic support were found to experience synapse loss and decreased mitogen-activated protein kinase (MAPK) phosphorylation. Furthermore, astrocytes contributed to neuronal viability, morphology, vascular endothelial growth factor (VEGF) secretion, and overall neuronal network functionality, highlighting the multifunctional role of astrocytes.

Human-Induced Pluripotent Stem Cell-Derived Neural Stem Cell Therapy Limits Tissue Damage and Promotes Tissue Regeneration and Functional Recovery in a Pediatric Piglet Traumatic-Brain-Injury Model

Traumatic brain injury (TBI) is a leading cause of death and disability in pediatric patients and often results in delayed neural development and altered connectivity, leading to lifelong learning, memory, behavior, and motor function deficits. Induced pluripotent stem cell-derived neural stem cells (iNSCs) may serve as a novel multimodal therapeutic as iNSCs possess neuroprotective, regenerative, and cell-replacement capabilities post-TBI. In this study, we evaluated the effects of iNSC treatment on cellular, tissue, and functional recovery in a translational controlled cortical impact TBI piglet model. Five days post-craniectomy (n = 6) or TBI (n = 18), iNSCs (n = 7) or PBS (n = 11) were injected into perilesional brain tissue. Modified Rankin Scale (mRS) neurological evaluation, magnetic resonance imaging, and immunohistochemistry were performed over the 12-week study period. At 12-weeks post-transplantation, iNSCs showed long-term engraftment and differentiation into neurons, astrocytes, and oligodendrocytes. iNSC treatment enhanced endogenous neuroprotective and regenerative activities indicated by decreasing intracerebral immune responses, preserving endogenous neurons, and increasing neuroblast formation. These cellular changes corresponded with decreased hemispheric atrophy, midline shift, and lesion volume as well as the preservation of cerebral blood flow. iNSC treatment increased piglet survival and decreased mRS scores. The results of this study in a predictive pediatric large-animal pig model demonstrate that iNSC treatment is a robust multimodal therapeutic that has significant promise in potentially treating human pediatric TBI patients.

Brucella abortus triggers the differential expression of immunomodulatory lncRNAs in infected murine macrophages

Introduction

The lncRNAs (long non-coding RNAs) are the most diverse group of non-coding RNAs and are involved in most biological processes including the immune response. While some of them have been recognized for their influence on the regulation of inflammatory activity, little is known in the context of infection by Brucella abortus, a pathogen that presents significant challenges due to its ability to manipulate and evade the host immune system. This study focuses on characterize the expression profile of LincRNA-cox2, Lethe, lincRNA-EPS, Malat1 and Gas5 during infection of macrophages by B. abortus.

Methods

Using public raw RNA-seq datasets we constructed for a lncRNA expression profile in macrophages Brucella-infected. In addition, from public RNA-seq raw datasets of RAW264.7 cells infected with B. abortus we constructed a transcriptomic profile of lncRNAs in order to know the expression of the five immunomodulating lncRNAs studied here at 8 and 24 h post-infection. Finally, we performed in vitro infection assays in RAW264.7 cells and peritoneal macrophages to detect by qPCR changes in the expression of these lncRNAs at first 12 hours post infection, a key stage in the infection cycle where Brucella modulates the immune response to survive.

Results

Our results demonstrate that infection of macrophages with Brucella abortus, induces significant changes in the expression of LincRNA-Cox2, Lethe, LincRNA-EPS, Gas5, and Malat1.

Discussion

The change in the expression profile of these immunomodulatory lncRNAs in response to infection, suggest a potential involvement in the immune evasion strategy employed by Brucella to facilitate its intracellular survival.

Voluntary running wheel exercise induces cognitive improvement post traumatic brain injury in mouse model through redressing aberrant excitation regulated by voltage-gated sodium channels 1.1, 1.3, and 1.6

Traumatic brain injury (TBI) leads to disturbed brain discharge rhythm, elevated excitability, anxiety-like behaviors, and decreased learning and memory capabilities. Cognitive dysfunctions severely affect the quality of life and prognosis of TBI patients, requiring effective rehabilitation treatment. Evidence indicates that moderate exercise after brain injury decreases TBI-induced cognitive decline. However, the underlying mechanism remains unelucidated. Our results demonstrate that TBI causes cognitive impairment behavior abnormalities and overexpression of Nav1.1, Nav1.3 and Nav1.6 proteins inside the hippocampus of mice models. Three weeks of voluntary running wheel (RW) exercise treatments before or/and post-injury effectively redressed the aberrant changes caused by TBI. Additionally, a 10% exercise-conditioned medium helped recover cell viability, neuronal sodium current and expressions of Nav1.1, Nav1.3 and Nav1.6 proteins across cultured neurons after injury. Therefore, the results validate the neuroprotection induced by voluntary RW exercise treatment before or/and post-TBI. The RW exercise-induced improvement in cognitive behaviors and neuronal excitability could be associated with correcting the Nav1.1, Nav1.3, and Nav1.6 expression levels. The current study proves that voluntary exercise is an effective treatment strategy against TBI. The study also highlights novel potential targets for rehabilitating TBI, including the Navs proteins.

TGF-β1 Protects Trauma-injured Murine Cortical Neurons by Upregulating L-type Calcium Channel Cav1.2 via the p38 Pathway

Traumatic brain injury (TBI) is a leading cause of disability and death in adolescents, and there is a lack of effective methods of treatment. The neuroprotective effects exerted by TGF-β1 can ameliorate a range of neuronal lesions in multiple central nervous system diseases. In this study, we used an in-vitro TBI model of mechanical injury on murine primary cortical neurons and the neuro-2a cell line to investigate the neuroprotective role played by TGF-β1 in cortical neurons in TBI. Our results showed that TGF-β1 significantly increased neuronal viability and inhibited apoptosis for 24 h after trauma. The expression of Ca_v1.2, an L-type calcium channel (LTCC) isoform, decreased significantly after trauma injury, and this change was reversed by TGF-β1. Nimodipine, a classic LTCC blocker, abolished the protective effect of TGF-β1 on trauma-induced neuronal apoptosis. The knockdown of Ca_v1.2 in differentiated neuro-2a cells significantly inhibited the anti-apoptosis effect of TGF-β1 exerted on injured neuro-2a cells. Moreover, TGF-β1 rescued and enhanced the trauma-suppressed neuro-2a intracellular Ca²⁺ concentration, while the effect of TGF-β1 was partially inhibited by nimodipine. TGF-β1 significantly upregulated the expression of Ca_v1.2 by activating the p38 MAPK pathway and by inhibiting trauma-induced neuronal apoptosis. In conclusion, TGF-β1 increased trauma-injured murine cortical neuronal activity and inhibited apoptosis by upregulating Cav1.2 channels via activating the p38 MAPK pathway. Therefore, the TGF-β1/p38 MAPK/Ca_v 1.2 pathway has the potential to be used as a novel therapeutic target for TBI.

Neutrophil to lymphocyte ratio predicts early growth of traumatic intracerebral haemorrhage

OBJECTIVE

The neutrophil to lymphocyte ratio (NLR) has been proposed to capture the inflammatory status of patients with various conditions involving the brain. This retrospective study aimed to explore the association between the NLR and the early growth of traumatic intracerebral haemorrhage (tICH) in patients with traumatic brain injury (TBI).

METHODS

A multicentre, observational cohort study was conducted. Patients with cerebral contusion undergoing baseline computed tomography for haematoma volume analysis within 6 h after primary injury and follow-up visits within 48 h were included. Routine blood tests were performed upon admission, and early growth of tICH was assessed. Prediction accuracies of the NLR for the early growth of tICH and subsequent surgical intervention in patients were analysed.

RESULTS

There were a total of 1077 patients who met the criteria included in the study cohort. Univariate analysis results showed that multiple risk factors were associated with the early growth of tICH and included in the following multivariate analysis models. The multivariate logistic regression analysis results revealed that the NLR was highly associated with the early growth of tICH (p < 0.001) while considering other risk factors in the same model. The prediction accuracy of the NLR for the early growth of tICH in patients is 82%.

INTERPRETATION

The NLR is easily calculated and might predict the early growth of tICH for patients suffering from TBI.

Role of IL-6 in the regulation of neuronal development, survival and function

The pleiotropic cytokine interleukin-6 (IL-6) is emerging as a molecule with both beneficial and destructive potentials. It can exert opposing actions triggering either neuron survival after injury or causing neurodegeneration and cell death in neurodegenerative or neuropathic disorders. Importantly, neurons respond differently to IL-6 and this critically depends on their environment and whether they are located in the peripheral or the central nervous system. In addition to its hub regulator role in inflammation, IL-6 is recently emerging as an important regulator of neuron function in health and disease, offering exciting possibilities for more mechanistic insight into the pathogenesis of mental, neurodegenerative and pain disorders and for developing novel therapies for diseases with neuroimmune and neurogenic pathogenic components.

Cost-reducing traits for agonistic head collisions: a case for neurophysiology

Many animal species have evolved extreme behaviors requiring them to engage in repeated high-impact collisions. These behaviors include mating displays like headbutting in sheep and drumming in woodpeckers. To our knowledge, these taxa do not experience any notable acute head trauma, even though the deceleration forces would cause traumatic brain injury in most animals. Previous research has focused on skeletomuscular morphology, biomechanics, and material properties in an attempt to explain how animals moderate these high-impact forces. However, many of these behaviors are understudied, and most morphological or computational studies make assumptions about the behavior without accounting for the physiology of an organism. Studying neurophysiological and immune adaptations that co-vary with these behaviors can highlight unique or synergistic solutions to seemingly deleterious behavioral displays. Here, we argue that selection for repeated, high-impact head collisions may rely on a suite of coadaptations in intracranial physiology as a cost-reducing mechanism. We propose that there are three physiological systems that could mitigate the effects of repeated head trauma: (i) the innate neuroimmune response, (ii) the glymphatic system, and (iii) the choroid plexus. These systems are interconnected yet can evolve in an independent manner. We then briefly describe the function of these systems, their role in head trauma, and research that has examined how these systems may evolve to help reduce the cost of repeated, forceful head impacts. Ultimately, we note that little is known about cost-reducing intracranial mechanisms making it a novel field of comparative study that is ripe for exploration.

Melatonin attenuates branch chain fatty acid induced apoptosis mediated neurodegeneration

Valproic acid (VPA)-a short branched chain fatty acid (BCFA), is widely recognized as an anticonvulsant and a mood-stabilizing drug, but various adverse effects of VPA have also been investigated. However, the impact of BCFAs aggregation on brain cells, in the pathogenesis of neurodegeneration remains elusive. The objective of this study is to understand the cellular mechanisms underlying VPA-induced neuronal cell death mediated by oxidative stress, and the neuroprotective role of exogenous melatonin treatment on VPA-induced cell death. Neurotoxicity of VPA and protective role exerted by melatonin were assessed in vitro in SH-SY5Y cells and in vivo in the cerebral cortex and cerebellum regions of Wistar rat brain. The results show that melatonin pre-treatment protects the cells from VPA-induced toxicity by exerting an anti-apoptotic and anti-inflammatory effect by regulating apoptotic proteins and pro-inflammatory cytokines. The findings of the present study emphasize novel insights of melatonin as a supplement for the prevention and treatment of neuronal dysfunction induced by VPA.

Mice Heterozygous for the Sodium Channel Scn8a (Nav1.6) Have Reduced Inflammatory Responses During EAE and Following LPS Challenge

Voltage gated sodium (Nav) channels contribute to axonal damage following demyelination in experimental autoimmune encephalomyelitis (EAE), a rodent model of multiple sclerosis (MS). The Nav1.6 isoform has been implicated as a primary contributor in this process. However, the role of Nav1.6 in immune processes, critical to the pathology of both MS and EAE, has not been extensively studied. EAE was induced with myelin oligodendrocyte (MOG35-55) peptide in Scn8admu/+ mice, which have reduced Nav1.6 levels. Scn8admu/+ mice demonstrated improved motor capacity during the recovery and early chronic phases of EAE relative to wild-type animals. In the optic nerve, myeloid cell infiltration and the effects of EAE on the axonal ultrastructure were also significantly reduced in Scn8admu/+ mice. Analysis of innate immune parameters revealed reduced plasma IL-6 levels and decreased percentages of Gr-1high/CD11b+ and Gr-1int/CD11b+ myeloid cells in the blood during the chronic phase of EAE in Scn8admu/+ mice. Elevated levels of the anti-inflammatory cytokines IL-10, IL-13, and TGF-β1 were also observed in the brains of untreated Scn8admu/+ mice. A lipopolysaccharide (LPS) model was used to further evaluate inflammatory responses. Scn8admu/+ mice displayed reduced inflammation in response to LPS challenge. To further evaluate if this was an immune cell-intrinsic difference or the result of changes in the immune or hormonal environment, mast cells were derived from the bone marrow of Scn8admu/+ mice. These mast cells also produced lower levels of IL-6, in response to LPS, compared with those from wild type mice. Our results demonstrate that in addition to its recognized impact on axonal damage, Nav1.6 impacts multiple aspects of the innate inflammatory response.

Enhancement of intrinsic neuronal excitability-mediated by a reduction in hyperpolarization-activated cation current (Ih ) in hippocampal CA1 neurons in a rat model of traumatic brain injury

Traumatic brain injury (TBI) is associated with epileptiform activity in the hippocampus; however, the underlying mechanisms have not been fully determined. The goal was to understand what changes take place in intrinsic neuronal physiology in the hippocampus after blunt force trauma to the cortex. In this context, hyperpolarization-activated cation current (I_h ) currents may have a critical role in modulating the neuronal intrinsic membrane excitability; therefore, its contribution to the TBI-induced hyperexcitability was assessed. In a model of TBI caused by controlled cortical impact (CCI), the intrinsic electrophysiological properties of pyramidal neurons were examined 1 week after TBI induction in rats. Whole-cell patch-clamp recordings were performed under current- and voltage-clamp conditions following ionotropic receptors blockade. Induction of TBI caused changes in the intrinsic excitability of pyramidal neurons, as shown by a significant increase and decrease in firing frequency and in the rheobase current, respectively (p < .05). The evoked firing rate and the action potential time to peak were also significantly increased and decreased, respectively (p < .05). In the TBI group, the amplitude of instantaneous and steady-state I_h currents was both significantly smaller than those in the control group (p < .05). The I_h current density was also significantly decreased (p < .001). Findings indicated that TBI led to an increase in the intrinsic excitability in CA1 pyramidal neurons and changes in I_h current could be, in part, one of the underlying mechanisms involved in this hyperexcitability.

Riluzole promotes neurological function recovery and inhibits damage extension in rats following spinal cord injury: a meta-analysis and systematic review

Spinal cord injury (SCI) is a devastating condition that has few treatment options. Riluzole, a sodium channel blocker used to treat amyotrophic lateral sclerosis, has been initially trialed in human SCI. We performed a systematic review to critically assess the efficacy of riluzole in locomotor recovery and damage extension in SCI rat models, and the potential for clinical translation. PubMed, Embase, Cochrane Library, and Chinese databases were searched from their inception date to March 2018. Two reviewers independently selected animal studies that evaluated neurological recovery and lesion area following riluzole treatment in SCI rat models, extracted data and assessed methodological quality. Pairwise meta-analysis, subgroup analysis, and network meta-analysis were performed to assess the effects of riluzole on SCI. Ten eligible studies were included. Two studies had high methodological quality. Overall, the Basso, Beattie, and Bresnahan scores were increased in riluzole-treated animals versus controls, and effect sizes showed a gradual increase from the 1st (five studies, n = 104, mean difference = 1.24, 95% CI = 0.11 to 2.37, p = 0.03) to 6th week after treatment (five studies, n = 120, mean difference = 2.34, 95% CI = 1.26 to 3.42, p < 0.0001). Riluzole was associated with improved outcomes in the inclined plane test and the tissue preservation area. Subgroup analyses suggested an association of locomotor recovery with riluzole dose. Network meta-analysis showed that 5 mg/kg riluzole exhibited greater protection than 2.5 and 8 mg/kg riluzole. Collectively, this review suggests that riluzole has a protective effect on SCI, with good safety and a clear mechanism of action and may be suitable for future clinical trials or applications. However, animal results should be interpreted with caution given the known limitations in animal experimental design and methodological quality.

A correlative analysis between inflammatory cytokines and trigeminal neuralgia or hemifacial spasm

BACKGROUND

It is necessary to understand the mechanism of trigeminal neuralgia (TN) and hemifacial spasm (HFS) in order to seek for an effective noninvasive remedy. As previous studies implied that inflammatory cytokines induced by demyelination following the nerve injury may be the initiated factor causing neuropathic pain, we attempt to analyze the correlation between cytokines and these hyperactive cranial nerve disorders.

METHOD

The consecutive patients whose diagnosis were confirmed by microvascular decompression surgery as primary TN or HFS caused by vascular compression and healthy volunteers between March and May 2018 in XinHua Hospital Shanghai JiaoTong University School of Medicine were recruited. Preoperatively, venous blood was collected and the protein concentrations of IL-1β, IL-2, IL-6, IL-8, IL-10, TNF-α and IFN-γ were determined with ELISA. Each cytokine was compared between the patients and healthy volunteers.

RESULTS

Ultimately, 28 healthy volunteers as well as 44 TN and 47 HFS patients were enrolled in this investigation. The serum levels of IL-1β, IL-6, IL-8 and TNF-α in either HFS or TN patients were significantly higher than that in healthy volunteers (p < 0.05), yet which were similar between TN and HFS patients (p > 0.05). Besides, there was a significantly correlation between IL-6 concentration and severity of HFS (r = 0.933, p < 0.05) or TN (r = 0.943, p < 0.05).

DISCUSSION

Vascular compression of trigeminal or facial nerve roots may induce a rise in variety of cytokines, and IL-6 may play an important role in the signaling pathways to generate ectopic impulses from these cranial nerves.

Serum levels of NLRP3 and HMGB-1 are associated with the prognosis of patients with severe blunt abdominal trauma

OBJECTIVES

To investigate the relationship between the serum levels of NLRP3 and HMGB-1 and the prognosis of patients with severe blunt abdominal trauma.

METHODS

In total, 299 patients were included in the current study from July 2014 to December 2015. All patients were divided into the mild/moderate blunt abdominal trauma group and the severe blunt abdominal trauma group according to their injury severity scores. Serum levels of NLRP3 and HMGB-1 were measured upon admission (0 h) and at 12 h, 24 h, 48 h, 72 h and 7 days after admission.

RESULTS

Compared with the healthy controls, both the mild/moderate and severe blunt abdominal trauma groups had higher serum levels of NLRP3 and HMGB-1 at admission. At all points, the serum levels of NLRP3 and HMGB-1 were significantly higher in the severe group than in the mild/moderate group. The serum levels of both NLRP3 and HMGB-1 were significantly higher in the deceased patients than in the living patients. The Kaplan-Meier curve showed that compared with patients with higher levels of NLRP3 or HMGB-1, those with lower levels had longer survival times. The serum levels of both NLRP3 and HMGB-1 were independent risk factors for 6-month mortality in severe blunt abdominal trauma patients.

CONCLUSION

The serum levels of NLRP3 and HMGB-1 were significantly elevated in severe blunt abdominal trauma patients, and the serum levels of both NLRP3 and HMGB-1 were correlated with 6-month mortality in severe blunt abdominal trauma patients.

Acute Inflammatory Biomarker Responses to Diffuse Traumatic Brain Injury in the Rat Monitored by a Novel Microdialysis Technique

Neuroinflammation is a major contributor to the progressive brain injury process induced by traumatic brain injury (TBI), and may play an important role in the pathophysiology of axonal injury. The immediate neuroinflammatory cascade cannot be characterized in the human setting. Therefore, we used the midline fluid percussion injury model of diffuse TBI in rats and a novel microdialysis (MD) method providing stable diffusion-driven biomarker sampling. Immediately post-injury, bilateral amphiphilic tri-block polymer coated MD probes (100 kDa cut off membrane) were inserted and perfused with Dextran 500 kDa-supplemented artificial cerebrospinal fluid (CSF) to optimize protein capture. Six hourly samples were analyzed for 27 inflammatory biomarkers (9 chemokines, 13 cytokines, and 5 growth factors) using a commercial multiplex biomarker kit. TBI (n = 6) resulted in a significant increase compared with sham-injured controls (n = 6) for five chemokines (eotaxin/CCL11, fractalkine/CX3CL1, LIX/CXCL5, monocyte chemoattractant protein [MCP]1α/CCL2, macrophage inflammatory protein [MIP]1α /CCL3), 10 cytokines (interleukin [IL]-1α, IL-1β, IL-4, IL-6, IL-10, IL-13, IL-17α, IL-18, interferon [IFN]-γ, tumor necrosis factor [TNF]-α), and four growth factors (epidermal growth factor [EGF], granulocyte-macrophage colony-stimulating factor [GM-CSF], leptin, vascular endothelial growth factor [VEGF]). Therefore, diffuse TBI was associated with an increased level of 18 of the 27 inflammatory biomarkers at one through six time points, during the observation period whereas the remaining 9 biomarkers were unaltered. The study shows that diffuse TBI induces an acute increase in a number of inflammatory biomarkers. The novel MD technique provides stable MD sampling suitable for further studies on the early neuroinflammatory cascade in TBI.

Innate immune responses to trauma

Trauma can affect any individual at any location and at any time over a lifespan. The disruption of macrobarriers and microbarriers induces instant activation of innate immunity. The subsequent complex response, designed to limit further damage and induce healing, also represents a major driver of complications and fatal outcome after injury. This Review aims to provide basic concepts about the posttraumatic response and is focused on the interactive events of innate immunity at frequent sites of injury: the endothelium at large, and sites within the lungs, inside and outside the brain and at the gut barrier.

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.