The neuroprotective role of inflammation in nervous system Injuries

Cerebral and Peripheral Immune Cell Changes following Rodent Juvenile Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of death and disability. TBI is associated with neuroinflammation, but temporal changes in immune and inflammatory signaling following TBI have not been fully elucidated. Furthermore, there have been no previous studies on changes in immune cell populations following TBI via the Closed Head Injury Model of Engineered Rotational Acceleration (CHIMERA). The current study aimed to determine the time course changes to inflammatory marker mRNA expression in the acute period following TBI in juvenile rats and to determine acute changes to brain and circulating immune cell populations. For this study, post-natal day (PND)-30 male Long Evans rats sustained a TBI or Sham TBI and were euthanized at 0, 3, 6, 12, 24, or 96 h post-injury. Prefrontal cortex and hippocampus samples were used to determine mRNA expression changes of inflammatory factors. The mRNA expression of the pro-inflammatory cytokine TNF-α was significantly elevated at 6 h post-injury in both regions evaluated. To evaluate immune cell populations, male Long Evans rats were euthanized at 48 h post-injury, and brain and blood samples were used for cell sorting by marker-specific antibodies. In the peripheral blood, there was an elevation in CD3+ total T cells, CD45R+ total B cells, and CD3+CD4+ helper T cells in the TBI subjects. However, there were no changes to natural killer cells or CD3+CD8+ cytotoxic T cell populations. In the brain, there was a reduction in CD11b/c+ monocytes/macrophages, but no changes in other immune cell populations. At 48 h post-injury, the TBI subjects also demonstrated expansion of the thymic medulla. These changes in the cerebral and blood immune cell populations and thymic medulla expansion may implicate the subacute recovery timeframe as a vulnerable window for the immune system in the pediatric population.

The inflammatory response to birth requires MyD88 and is driven by both mother and offspring

Birth is an inflammatory event for the newborn, characterized by elevations in interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α peripherally and/or centrally, as well as changes in brain microglia. However, the mechanism(s) underlying these responses is unknown. Toll-like receptors (TLRs) play crucial roles in innate immunity and initiate inflammatory cascades upon recognition of endogenous or exogenous antigens. Most TLR signaling depends on the adaptor molecule myeloid differentiation primary response 88 (MyD88). We independently varied MyD88 gene status in mouse dams and their offspring to determine whether the inflammatory response to birth depends on MyD88 signaling and, if so, whether that signaling occurs in the offspring, the mother, or both. We find that the perinatal surges in plasma IL-6 and brain expression of TNF-α depend solely on MyD88 gene status of the offspring, whereas postnatal increases in plasma IL-10 and TNF-α depend on MyD88 in both the pup and dam. Interestingly, MyD88 genotype of the dam primarily drives differences in offspring brain microglial density and has robust effects on developmental neuronal cell death. Milk cytokines were evaluated as a possible source of postnatal maternal influence; although we found high levels of CXCL1/GROα and several other cytokines in ingested post-partum milk, their presence did not require MyD88. Thus, the inflammatory response previously described in the late-term fetus and newborn depends on MyD88 (and, by extension, TLRs), with signaling in both the dam and offspring contributing. Unexpectedly, naturally-occuring neuronal cell death in the newborn is modulated primarily by maternal MyD88 gene status.

Beyond an inflammatory mediator: Interleukin-1 in neurophysiology

NEW FINDINGS

What is the topic of this review? This review focuses on the physiological role of the cytokine interleukin-1β in the CNS. What advances does it highlight? Traditionally, interleukin-1β is known as a key mediator of inflammation and immunity. This review highlights the more recent findings describing how interleukin-1β signalling is required to maintain homeostasis in the CNS.

ABSTRACT

Since its discovery in the early 1940s, the interleukin-1 (IL-1) cytokine family has been associated primarily with acute and chronic inflammation. The family member IL-1β is produced by different leucocytes, endothelial cells and epithelial cells. This cytokine has been characterized as a key modulator of inflammation and innate immunity because it induces the transcription of several downstream inflammatory genes. More recently, several groups have demonstrated that IL-1β production is also required to maintain homeostasis in several organ systems. This review focuses on providing an overview of the more recently characterized role of IL-1β in the physiology of the CNS. So far, IL-1β signalling has been implicated in neuronal survival, neurite growth, synaptic pruning, synaptic transmission, neuroplasticity and neuroendocrine functions.

Birth triggers an inflammatory response in the neonatal periphery and brain

Birth is preceded by inflammation at the fetal/maternal interface. Additionally, the newborn experiences stimuli that under any other circumstance could elicit an immune response. It is unknown, however, whether birth elicits an inflammatory response in the newborn that extends to the brain. Moreover, it is unknown whether birth mode may alter such a response. To study these questions, we first measured corticosterone and pro- and anti-inflammatory cytokines in plasma of mouse offspring at several timepoints spaced closely before and after a vaginal or Cesarean birth. We found highest levels of IL-6 one day before birth and surges in corticosterone and IL-10 just after birth, regardless of birth mode. We next examined the neuroimmune response by measuring cytokine mRNA expression and microglial number and morphology in the paraventricular nucleus of the hypothalamus and hippocampus around the time of birth. We found a marked increase in TNF-α expression in both brain regions a day after birth, and rapid increases in microglial cell number in the first three days postnatal, with subtle differences by birth mode. To test whether the association between birth and cytokine production or expansion of microglia is causal, we manipulated birth timing. Remarkably, advancing birth by a day advanced the increases in all of the markers tested. Thus, birth triggers an immune response in the body and brain of offspring. Our results may provide a mechanism for effects of birth (e.g., acute changes in cell death and neural activation) previously reported in the newborn brain.

Extreme prematurity: Risk and resiliency

Individuals born extremely preterm (before 28 weeks of gestation) comprise only about 0.7% of births in the United States and an even lower proportion in other high resource countries. However, these individuals account for a disproportionate number of children with cerebral palsy, intellectual deficit, autism spectrum disorder, attention deficit hyperactivity disorder, and epilepsy. This review describes two large multiple center cohorts comprised of individuals born extremely preterm: the EPICURE cohort, recruited 1995 in the United Kingdom and the Republic of Ireland, and the Extremely Low Gestational Age Newborn (ELGAN), recruited 2002-2004 in five states in the United States. The primary focus of these studies has been neurodevelopmental disorders, but also of interest are growth, respiratory illness, and parent- and self-reported global health and well-being. Both of these studies indicate that among individuals born extremely preterm the risks of most neurodevelopmental disorders are increased. Early life factors that contribute to this risk include perinatal brain damage, some of which can be identified using neonatal head ultrasound, bronchopulmonary dysplasia, and neonatal systemic inflammation. Prenatal factors, particularly the family's socioeconomic position, also appear to contribute to risk. For most adverse outcomes, the risk is higher in males. Young adults born extremely preterm who have neurodevelopmental impairment, as compared to those without such impairment, rate their quality of life lower. However, young adults born extremely preterm who do not have neurodevelopmental impairments rate their quality of life as being similar to that of young adults born at term. Finally, we summarize the current state of interventions designed to improve the life course of extremely premature infants, with particular focus on efforts to prevent premature birth and on postnatal efforts to prevent adverse neurodevelopmental outcomes.

Curcumin suppress inflammatory response in traumatic brain injury via p38/MAPK signaling pathway

Traumatic brain injury (TBI) is a common disease worldwide with a high mortality and disability rate and is closely related to the inflammatory response. However, the molecular mechanisms during the pathophysiological responses are not completely understood. This study was conducted to investigate the protective effect of curcumin on TBI and the molecular mechanisms of the p38/MAPK signal pathway. We found that curcumin remarkably ameliorated secondary brain injury after TBI, including effects on the neurological severity score and inflammation. After injection of curcumin, the neurological function score of mice decreased significantly. Curcumin exhibited antiinflammatory pharmacological effects, as reflected by inhibition of inflammatory factors (e.g., interleukin [IL]-1β, IL-6, and tumor necrosis factor [TNF]-α). Additionally, curcumin notably reduced the expression of p-p38 according to western blotting and immunohistochemical analyses. In conclusion, curcumin remarkably alleviated posttraumatic inflammation and thus shows potential for treating inflammation associated with TBI.

Urinary metabolomic signatures as indicators of injury severity following traumatic brain injury: A pilot study

BACKGROUND

Analysis of fluid metabolites has the potential to provide insight into the neuropathophysiology of injury in patients with traumatic brain injury (TBI).

OBJECTIVE

Using a 1H nuclear magnetic resonance (NMR)-based quantitative metabolic profiling approach, this study determined (1) if urinary metabolites change during recovery in patients with mild to severe TBI; (2) whether changes in urinary metabolites correlate to injury severity; (3) whether biological pathway analysis reflects mechanisms that mediate neural damage/repair throughout TBI recovery.

METHODS

Urine samples were collected within 7 days and at 6-months post-injury in male participants (n = 8) with mild-severe TBI. Samples were analyzed with NMR-based quantitative spectroscopy for metabolomic profiles and analyzed with multivariate statistical and machine learning-based analyses.

RESULTS

Lower levels of homovanillate (R = -0.74, p ≤ 0.001), L-methionine (R = -0.78, p < 0.001), and thymine (R = -0.85, p < 0.001) negatively correlated to injury severity. Pathway analysis revealed purine metabolism to be a primary pathway (p < 0.01) impacted by TBI.

CONCLUSION

This study provides pilot data to support the use of urinary metabolites in clinical practice to better interpret biochemical changes underlying TBI severity and recovery. The discovery of urinary metabolites as biomarkers may assist in objective and rapid identification of TBI severity and prognosis. Thus, 1H NMR metabolomics has the potential to facilitate the adaptation of treatment programs that are personalized to the patient's needs.

Umbilical cord mesenchymal stem cells promote neurological repair after traumatic brain injury through regulating Treg/Th17 balance

Traumatic brain injury (TBI) is a brain injury resulting from blunt mechanical external forces, which is a crucial public health and socioeconomic problem worldwide. TBI is one of the leading causes of death or disability. The primary injury of TBI is generally irreversible. Secondary injury caused by neuroinflammation could result in exacerbation of patients, which indicated that anti-inflammation and immunomodulatory were necessary for the treatment of TBI. Accumulated evidence reveals that the transplantation of umbilical cord mesenchymal stem cells (UCMSCs) could regulate the microenvironment in vivo and keep a balance of helper T 17(Th17)/ regulatory T cell (Treg). Therefore, it is reasonable to hypothesize that the UCMSCs could repair neurological impairment by maintaining the balance of Th17/Treg after TBI. In the study, we observed the phenomenon of trans-differentiation of T lymphocytes into Th17 cells after TBI. Rats were divided into Sham, TBI, and TBI + UCMSCs groups to explore the effects of the UCMSCs. The results manifested that trans-differentiation of Th17 into Treg was facilitated by UCMSCs, which was followed by promotion of neurological recovery and improvement of learning and memory in TBI rats. Furthermore, UCMSCs decreased the phosphorylation of nuclear factor-kappa B (NF-κB) and increased the expression of mothers against decapentaplegic homolog 3 (Smad3) in vivo and vitro experiments. In conclusion, UCMSCs maintained Th17/Treg balance via the transforming growth factor-β (TGF-β)/ Smad3/ NF-κB signaling pathway.

Treelet transform analysis to identify clusters of systemic inflammatory variance in a population with moderate-to-severe traumatic brain injury

BACKGROUND

Inflammatory cascades following traumatic brain injury (TBI) can have both beneficial and detrimental effects on recovery. Single biomarker studies do not adequately reflect the major arms of immunity and their relationships to long-term outcomes. Thus, we applied treelet transform (TT) analysis to identify clusters of interrelated inflammatory markers reflecting major components of systemic immune function for which substantial variation exists among individuals with moderate-to-severe TBI.

METHODS

Serial blood samples from 221 adults with moderate-to-severe TBI were collected over 1-6 months post-injury (n = 607 samples). Samples were assayed for 33 inflammatory markers using Millipore multiplex technology. TT was applied to standardized mean biomarker values generated to identify latent patterns of correlated markers. Treelet clusters (TC) were characterized by biomarkers related to adaptive immunity (TC1), innate immunity (TC2), soluble molecules (TC3), allergy immunity (TC4), and chemokines (TC5). For each TC, a score was generated as the linear combination of standardized biomarker concentrations and cluster load for each individual in the cohort. Ordinal logistic or linear regression was used to test associations between TC scores and 6- and 12-month Glasgow Outcome Scale (GOS), Disability Rating Scale (DRS), and covariates.

RESULTS

When adjusting for clinical covariates, TC5 was significantly associated with 6-month GOS (odds ratio, OR = 1.44; p-value, p = 0.025) and 6-month DRS scores (OR = 1.46; p = 0.013). TC5 relationships were attenuated when including all TC scores in the model (GOS: OR = 1.29, p = 0.163; DRS: OR = 1.33, p = 0.100). When adjusting for all TC scores and covariates, only TC3 was associated with 6- and 12-month GOS (OR = 1.32, p = 0.041; OR = 1.39, p = 0.002) and also 6- and 12-month DRS (OR = 1.38, p = 0.016; OR = 1.58, p = 0.0002). When applying TT to inflammation markers significantly associated with 6-month GOS, multivariate modeling confirmed that TC3 remained significantly associated with GOS. Biomarker cluster membership remained consistent between the GOS-specific dendrogram and overall dendrogram.

CONCLUSIONS

TT effectively characterized chronic, systemic immunity among a cohort of individuals with moderate-to-severe TBI. We posit that chronic chemokine levels are effector molecules propagating cellular immune dysfunction, while chronic soluble receptors are inflammatory damage readouts perpetuated, in part, by persistent dysfunctional cellular immunity to impact neuro-recovery.

The effects of Taurine supplementation on inflammatory markers and clinical outcomes in patients with traumatic brain injury: a double-blind randomized controlled trial

Background

Traumatic brain injury is a public health concern and is the main cause of death among various types of trauma. The inflammatory conditions due to TBI are associated with unfavorable clinical outcomes. Taurine has been reported to have immune-modulatory effects. Thus, the aim of this study was to survey the effect of taurine supplementation in TBI patients.

Methods

In this study, 32 patients with TBI were randomized into two groups. The treatment group received 30 mg/kg/day of taurine in addition to the Standard Entera Meal and the control group received Standard Entera Meal for 14 days. Prior to and following the intervention, the patients were investigated in terms of serum levels of IL-6, IL-10, hs-CRP and TNF-α as well as APACHEII, SOFA and NUTRIC scores, Glasgow coma scale and weight. In addition, the length of Intensive Care Unit stay, days of dependence on ventilator and 30-day mortality were studied. SPSS software (version 13.0) was used for data analysis.

Results

Taurine significantly decreased the serum levels of IL-6 (p = 0.04) and marginally APACHEII score (p = 0.05). In addition, weight loss was significantly lower in taurine group (p = 0.03). Furthermore, taurine significantly increased the GCS (p = 0.03). The groups were not different significantly in terms of levels of IL-10, hs-CRP, and TNF-α, SOFA and NUTRIC scores, 30-day mortality, length of ICU stay and days of dependence on ventilator.

Conclusion

According to the results of the present study, taurine supplementation can reduce the IL-6 levels as one of the important inflammatory markers in these patients; and enhances the clinical outcomes too.

Trial registration

IRCT, IRCT20180514039657N1. Registered 22 June 2018.

Revisiting Traumatic Brain Injury: From Molecular Mechanisms to Therapeutic Interventions

Studying the complex molecular mechanisms involved in traumatic brain injury (TBI) is crucial for developing new therapies for TBI. Current treatments for TBI are primarily focused on patient stabilization and symptom mitigation. However, the field lacks defined therapies to prevent cell death, oxidative stress, and inflammatory cascades which lead to chronic pathology. Little can be done to treat the mechanical damage that occurs during the primary insult of a TBI; however, secondary injury mechanisms, such as inflammation, blood-brain barrier (BBB) breakdown, edema formation, excitotoxicity, oxidative stress, and cell death, can be targeted by therapeutic interventions. Elucidating the many mechanisms underlying secondary injury and studying targets of neuroprotective therapeutic agents is critical for developing new treatments. Therefore, we present a review on the molecular events following TBI from inflammation to programmed cell death and discuss current research and the latest therapeutic strategies to help understand TBI-mediated secondary injury.

Crosstalk between obesity, diabetes, and alzheimer's disease: Introducing quercetin as an effective triple herbal medicine

Obesity and diabetes are the most common metabolic disorders, which are strongly related to Alzheimer's disease (AD) in aging. Diabetes and obesity can lead to the accumulation of amyloid plaques, neurofibrillary tangles (NFTs), and other symptoms of AD through several pathways, including insulin resistance, hyperglycemia, hyperinsulinemia, chronic inflammation, oxidative stress, adipokines dysregulation, and vascular impairment. Currently, the use of polyphenols has been expanded in animal models and in-vitro studies because of their comparatively negligible adverse effects. Among them, quercetin (QT) is one of the most abundant polyphenolic flavonoids, which is present in fruits and vegetables and displays many biological, health-promoting effects in a wide range of diseases. The low bioavailability and poor solubility of QT have also led researchers to make various QT-involved nanoparticles (NPs) to overcome these limitations. In this paper, we review significant molecular mechanisms induced by diabetes and obesity that increase AD pathogenesis. Then, we summarize in vitro, in vivo, and clinical evidence regarding the anti-Alzheimer, anti-diabetic and anti-obesity effects of QT. Finally, QT in pure and combination form using NPs has been suggested as a promising therapeutic agent for future studies.

Transplantation of R-GSIK scaffold with mesenchymal stem cells improves neuroinflammation in a traumatic brain injury model

Neural tissue engineering has been introduced as a novel therapeutic strategy for traumatic brain injury (TBI). Transplantation of mesenchymal stem cells (MSCs) has been demonstrated to improve functional outcome of brain injury, and RADA4GGSIKVAV (R-GSIK), a self-assembling nano-peptide scaffold, has been suggested to promote the behavior of stem cells. This study was designed to determine the ability of the R-GSIK scaffold in supporting the effects of MSCs on motor function activity and inflammatory responses in an experimental TBI model. A significant recovery of motor function was observed in rats that received MSCs+R-GSIK compared with the control groups. Further analysis showed a reduction in the number of reactive astrocytes and microglial cells in the MSCs and MSCs+R-GSIK groups compared with the control groups. Furthermore, western blot analysis indicated a significant reduction in pro-inflammatory cytokines, such as TLR4, TNF, and IL6, in the MSCs and MSCs+R-GSIK groups compared with the TBI, vehicle, and R-GSIK groups. Overall, this study strengthens the idea that the co-transplantation of MSCs with R-GSIK can increase functional outcomes by preparing a beneficial environment. This improvement may be explained by the immunomodulatory effects of MSCs and the self-assembling nano-scaffold peptide.

Effects of maternal L-proline supplementation on inflammatory cytokines at the placenta and fetus interface of mice

Dietary L-proline (proline) supplementation during gestation enhances fetal survival and placental development in mice. The objective of the present study was to test the hypothesis that this beneficial effect of proline was associated with alterations in inflammatory response at the placenta and fetus interface. Populations of immune cells present in peripheral blood mononuclear cells (PBMC) were determined by flow cytometry analysis. The concentrations of immunoglobulins in plasma, and the concentrations of cytokines in plasma, uterus, placenta, and amniotic fluid were measured using a bead-based immunoassay. The data showed that proline supplementation led to higher (P < 0.05) populations of B lymphocytes (CD3^-CD19⁺), natural killer (NK) cells (CD3^-NK1.1⁺), and dendritic cells (DCs, CD11c⁺MHCII⁺) in peripheral blood, as compared with the controls. Conversely, mice fed a proline-supplemented diet had a lower population of neutrophils (CD11b⁺F4/80^-). Further study showed that proline supplementation decreased (P < 0.05) the concentrations of (1) interleukin (IL)-23, IL-1α, and IL-6 in plasma; (2) IL-6 in the uterus; and (3) tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein (MCP)-1, and IL-17 in the placenta; and (4) interferon (IFN)-γ in amniotic fluid, compared with controls. Conversely, proline supplementation resulted in higher (P < 0.05) concentrations of (1) IL-10, IL-17 and granulocyte-macrophage colony-stimulating factor (GM-CSF) in plasma; (2) IL-10 and IL-1α in the uterus; and (3) IL-1α, IL-1β, IL-10, IL-27, and IFN-β in amniotic fluid, compared with controls. Moreover, concentrations of immunoglobulin (Ig) G2b and IgM were enhanced (P < 0.05) by proline administration. Taken together, our results reveal a regulatory effect of proline in the immunological response at the maternal-fetal interface, which is critical for embryonic development and fetal survival.

The Potassium SK Channel Activator NS309 Protects Against Experimental Traumatic Brain Injury Through Anti-Inflammatory and Immunomodulatory Mechanisms

Neuroinflammation plays important roles in neuronal cell death and functional deficits after TBI. Small conductance Ca²⁺-activated K⁺ channels (SK) have been shown to be potential therapeutic targets for treatment of neurological disorders, such as stroke and Parkinson’s disease (PD). The aim of the present study was to investigate the role of SK channels in an animal model of TBI induced by controlled cortical impact (CCI). The SK channels activator NS309 at a concentration of 2 mg/kg was administered by intraperitoneal injection, and no obviously organ-related toxicity of NS309 was found in Sprague-Dawley (SD) rats. Treatment with NS309 significantly reduced brain edema after TBI, but had no effect on contusion volume. This protection can be observed even when the administration was delayed by 4 h after injury. NS309 attenuated the TBI-induced deficits in neurological function, which was accompanied by the reduced neuronal apoptosis. The results of immunohistochemistry showed that NS309 decreased the number of neutrophils, lymphocytes, and microglia cells, with no effect on astrocytes. In addition, NS309 markedly decreased the levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and chemokines (MCP-1, MIP-2, and RANTES), but increased the levels of anti-inflammatory cytokines (IL-4, IL-10, and TGF-β1) after TBI. The results of RT-PCR and western blot showed that NS309 increased TSG-6 expression and inhibited NF-κB activation. Furthermore, knockdown of TSG-6 using in vivo transfection with TSG-6 specific shRNA partially reversed the protective and anti-inflammatory effects of NS309 against TBI. In summary, our results indicate that the SK channel activator NS309 could modulate inflammation-associated immune cells and cytokines via regulating the TSG-6/NF-κB pathway after TBI. The present study offers a new sight into the mechanisms responsible for SK channels activation with implications for the treatment of TBI.

Calpain inhibitor MDL28170 improves the transplantation-mediated therapeutic effect of bone marrow-derived mesenchymal stem cells following traumatic brain injury

Background

Studies have shown that transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) protects against brain damage. However, the low survival number of transplanted BMSCs remains a pertinent challenge and can be attributed to the unfavorable microenvironment of the injured brain. It is well known that calpain activation plays a critical role in traumatic brain injury (TBI)-mediated inflammation and cell death; previous studies showed that inhibiting calpain activation is neuroprotective after TBI. Thus, we investigated whether preconditioning with the calpain inhibitor, MDL28170, could enhance the survival of BMSCs transplanted at 24 h post TBI to improve neurological function.

Methods

TBI rat model was induced by the weight-drop method, using the gravitational forces of a free falling weight to produce a focal brain injury. MDL28170 was injected intracranially at the lesion site at 30 min post TBI, and the secretion levels of neuroinflammatory factors were assessed 24 h later. BMSCs labeled with green fluorescent protein (GFP) were locally administrated into the lesion site of TBI rat brains at 24 h post TBI. Immunofluorescence and histopathology were performed to evaluate the BMSC survival and the TBI lesion volume. Modified neurological severity scores were chosen to evaluate the functional recovery. The potential mechanisms by which MDL28170 is involved in the regulation of inflammation signaling pathway and cell apoptosis were determined by western blot and immunofluorescence staining.

Results

Overall, we found that a single dose of MDL28170 at acute phase of TBI improved the microenvironment by inhibiting the inflammation, facilitated the survival of grafted GFP-BMSCs, and reduced the grafted cell apoptosis, leading to the reduction of lesion cavity. Furthermore, a significant neurological function improvement was observed when BMSCs were transplanted into a MDL28170-preconditioned TBI brains compared with the one without MDL28170-precondition group.

Conclusions

Taken together, our data suggest that MDL28170 improves BMSC transplantation microenvironment and enhances the neurological function restoration after TBI via increased survival rate of BMSCs. We suggest that the calpain inhibitor, MDL28170, could be pursued as a new combination therapeutic strategy to advance the effects of transplanted BMSCs in cell-based regenerative medicine.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1210-4) contains supplementary material, which is available to authorized users.

STING-mediated type-I interferons contribute to the neuroinflammatory process and detrimental effects following traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) represents a major cause of disability and death worldwide with sustained neuroinflammation and autophagy dysfunction contributing to the cellular damage. Stimulator of interferon genes (STING)-induced type-I interferon (IFN) signalling is known to be essential in mounting the innate immune response against infections and cell injury in the periphery, but its role in the CNS remains unclear. We previously identified the type-I IFN pathway as a key mediator of neuroinflammation and neuronal cell death in TBI. However, the modulation of the type-I IFN and neuroinflammatory responses by STING and its contribution to autophagy and neuronal cell death after TBI has not been explored.

METHODS

C57BL/6J wild-type (WT) and STING^-/- mice (8-10-week-old males) were subjected to controlled cortical impact (CCI) surgery and brains analysed by QPCR, Western blot and immunohistochemical analyses at 2 h or 24 h. STING expression was also analysed by QPCR in post-mortem human brain samples.

RESULTS

A significant upregulation in STING expression was identified in late trauma human brain samples that was confirmed in wild-type mice at 2 h and 24 h after CCI. This correlated with an elevated pro-inflammatory cytokine profile with increased TNF-α, IL-6, IL-1β and type-I IFN (IFN-α and IFN-β) levels. This expression was suppressed in the STING^-/- mice with a smaller lesion volume in the knockout animals at 24 h post CCI. Wild-type mice also displayed increased levels of autophagy markers, LC3-II, p62 and LAMP2 after TBI; however, STING^-/- mice showed reduced LAMP2 expression suggesting a role for STING in driving dysfunctional autophagy after TBI.

CONCLUSION

Our data implicates a detrimental role for STING in mediating the TBI-induced neuroinflammatory response and autophagy dysfunction, potentially identifying a new therapeutic target for reducing cellular damage in TBI.

Birth delivery mode alters perinatal cell death in the mouse brain

Labor and a vaginal delivery trigger changes in peripheral organs that prepare the mammalian fetus to survive ex utero. Surprisingly little attention has been given to whether birth also influences the brain, and to how alterations in birth mode affect neonatal brain development. These are important questions, given the high rates of cesarean section (C-section) delivery worldwide, many of which are elective. We examined the effect of birth mode on neuronal cell death, a widespread developmental process that occurs primarily during the first postnatal week in mice. Timed-pregnant dams were randomly assigned to C-section deliveries that were yoked to vaginal births to carefully match gestation length and circadian time of parturition. Compared with rates of cell death just before birth, vaginally-born offspring had an abrupt, transient decrease in cell death in many brain regions, suggesting that a vaginal delivery is neuroprotective. In contrast, cell death was either unchanged or increased in C-section-born mice. Effects of delivery mode on cell death were greatest for the paraventricular nucleus of the hypothalamus (PVN), which is central to the stress response and brain-immune interactions. The greater cell death in the PVN of C-section-delivered newborns was associated with a reduction in the number of PVN neurons expressing vasopressin at weaning. C-section-delivered mice also showed altered vocalizations in a maternal separation test and greater body mass at weaning. Our results suggest that vaginal birth acutely impacts brain development, and that alterations in birth mode may have lasting consequences.

Microglia and CNS Interleukin-1: Beyond Immunological Concepts

Activation of microglia and expression of the inflammatory cytokine interleukin-1 (IL-1) in the CNS have become almost synonymous with neuroinflammation. In numerous studies, increased CNS IL-1 expression and altered microglial morphology have been used as hallmarks of CNS inflammation. A central concept of how CNS IL-1 and microglia influence functions of the nervous system was derived from the notion initially generated in the peripheral immune system: IL-1 stimulates monocyte/macrophage (the peripheral counterparts of microglia) to amplify inflammation. It is increasingly clear, however, CNS IL-1 acts on other targets in the CNS and microglia participates in many neural functions that are not related to immunological activities. Further, CNS exhibits immunological privilege (although not as absolute as previously thought), rendering amplification of inflammation within CNS under stringent control. This review will analyze current literature to evaluate the contribution of immunological and non-immunological aspects of microglia/IL-1 interaction in the CNS to gain insights for how these aspects might affect health and disease in the nervous tissue.

The microbiota influences cell death and microglial colonization in the perinatal mouse brain

The mammalian fetus develops in a largely sterile environment, and direct exposure to a complex microbiota does not occur until birth. We took advantage of this to examine the effect of the microbiota on brain development during the first few days of life. The expression of anti- and pro-inflammatory cytokines, developmental cell death, and microglial colonization in the brain were compared between newborn conventionally colonized mice and mice born in sterile, germ-free (GF) conditions. Expression of the pro-inflammatory cytokines interleukin 1β and tumor necrosis factor α was markedly suppressed in GF newborns. GF mice also had altered cell death, with some regions exhibiting higher rates (paraventricular nucleus of the hypothalamus and the CA1 oriens layer of the hippocampus) and other regions exhibiting no change or lower rates (arcuate nucleus of the hypothalamus) of cell death. Microglial labeling was elevated in GF mice, due to an increase in both microglial cell size and number. The changes in cytokine expression, cell death and microglial labeling were evident on the day of birth, but were absent on embryonic day 18.5, approximately one-half day prior to expected delivery. Taken together, our results suggest that direct exposure to the microbiota at birth influences key neurodevelopmental events and does so within hours. These findings may help to explain some of the behavioral and neurochemical alterations previously seen in adult GF mice.

Weekly follow up of acute lesions in three early multiple sclerosis patients using MR spectroscopy and diffusion

OBJECT

Pathophysiological mechanisms underlying multiple sclerosis (MS) lesion formation, including inflammation, demyelination/remyelination and axonal damage, and their temporal evolution are still not clearly understood. To this end, three acute white matter lesions were monitored using a weekly multimodal magnetic resonance (MR) protocol.

MATERIALS AND METHODS

Three untreated patients with early relapsing-remitting MS and one healthy control subject were followed weekly for two months. MR protocol included conventional MR imaging (MRI), diffusion tensor imaging (DTI), and localized MR spectroscopy (MRS), performed on the largest gadolinium-enhancing lesion, selected at the first exam.

RESULTS

Mean diffusivity increased and fractional anisotropy decreased in lesions compared to healthy control. Cho/Cr ratios remained elevated in lesions throughout the follow-up. In contrast, temporal profiles of mI/Cr ratios varied between patients' lesions. For patient 1, mI/Cr ratios were already elevated at the beginning of the follow-up. Patients 2 and 3 ratios increase was delayed by two and five weeks. Blood-brain barrier (BBB) recovery occurred after three weeks.

CONCLUSION

This multimodal MR follow-up highlighted the complementary role of DTI and MRS in identifying temporal relationships between BBB disruption, inflammation, and demyelination. Diffusion metrics showed high sensitivity to detect inflammatory processes. The different temporal profiles of mI suggested a potential better specificity to monitor pathological mechanisms occurring after lesion formation, such as glial proliferation and remyelination.

In immune defense: redefining the role of the immune system in chronic disease

The recognition of altered immune system function in many chronic disease states has proven to be a pivotal advance in biomedical research over the past decade. For many metabolic and mood disorders, this altered immune activity has been characterized as inflammation, with the attendant assumption that the immune response is aberrant. However, accumulating evidence challenges this assumption and suggests that the immune system may be mounting adaptive responses to chronic stressors. Further, the inordinate complexity of immune function renders a simplistic, binary model incapable of capturing critical mechanistic insights. In this perspective article, we propose alternative paradigms for understanding the role of the immune system in chronic disease. By invoking allostasis or systems biology rather than inflammation, we can ascribe greater functional significance to immune mediators, gain newfound appreciation of the adaptive facets of altered immune activity, and better avoid the potentially disastrous effects of translating erroneous assumptions into novel therapeutic strategies.

Matrine promotes NT3 expression in CNS cells in experimental autoimmune encephalomyelitis

Neurotrophin 3 (NT3) is a potent neurotrophic factor for promoting remyelination and recovery of neuronal function; upregulation of its expression in the central nervous system (CNS) is thus of major therapeutic importance for neurological deficits. Matrine (MAT), a quinolizidine alkaloid derived from the herb Radix Sophorae Flavescent, has been recently reported to effectively ameliorate clinical signs in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), by secreting antiinflammatory cytokines. In the present study, our goal was to investigate whether MAT could affect NT3 expression of glial cells in the CNS, the major cell populations in the CNS foci of MS/EAE. We found that MAT markedly upregulated NT3 expression in the CNS not only by microglia/macrophages and astrocytes, but also by oligodendrocyte precursor cells, indicative of both paracrine and autocrine effects on myelinating cells. While MAT treatment reduced the numbers of iNOS⁺ M1, but increased Arg1⁺ M2 microglia/macrophage phenotypes, NT3 expression was upregulated in both phenotypes. These results indicate that MAT therapy for EAE acts, at least in part, by stimulating local production of NT3 by glial cells in the CNS, which protects neural cells from CNS inflammation-induced tissue damage.

A simple and rapid method of isolation of active polypeptide complex, yolkin, from chicken egg yolk

A large number of bioactive peptides isolated from natural sources are known to play important physiological roles in the human body. It is possible to use these as alternative therapy agents. One example is yolkin which can be useful as a food supplement, a natural therapeutic agent for preventing and treating cognitive disorders of various origins, preferably in patients with unsatisfactory responses to known therapies. A new simple method of isolation of yolkin based on precipitation with ethanol or acetone was developed. The best precipitation efficiency of both ethanol and acetone was achieved when stirred into the starting material to a final concentration of 70%. These methods preserved the ability of yolkin to stimulate human whole blood cells to release anti-inflammatory cytokines and neurotrophins. At first we indicated that yolkin displayed a potential neuroprotective effect by the ability to stimulate cells to produce pro-survival brain derived neurotrophic factor (BDNF).

Optical coherence tomography and T cell gene expression analysis in patients with benign multiple sclerosis

Benign multiple sclerosis is a retrospective diagnosis based primarily on a lack of motor symptom progression. Recent findings that suggest patients with benign multiple sclerosis experience non-motor symptoms highlight the need for a more prospective means to diagnose benign multiple sclerosis early in order to help direct patient care. In this study, we present optical coherence tomography and T cell neurotrophin gene analysis findings in a small number of patients with benign multiple sclerosis. Our results demonstrated that retinal nerve fiber layer was mildly thinned, and T cells had a distinct gene expression profile that included upregulation of interleukin 10 and leukemia inhibitory factor, downregulation of interleukin 6 and neurotensin high affinity receptor 1 (a novel neurotrophin receptor). These findings add evidence for further investigation into optical coherence tomography and mRNA profiling in larger cohorts as a potential means to diagnose benign multiple sclerosis in a more prospective manner.

The multifaceted role of metalloproteinases in physiological and pathological conditions in embryonic and adult brains

Matrix metalloproteinases (MMPs) are a large family of ubiquitous extracellular endopeptidases, which play important roles in a variety of physiological and pathological conditions, from the embryonic stages throughout adult life. Their extraordinary physiological "success" is due to concomitant broad substrate specificities and strict regulation of their expression, activation and inhibition levels. In recent years, MMPs have gained increasing attention as significant effectors in various aspects of central nervous system (CNS) physiology. Most importantly, they have been recognized as main players in a variety of brain disorders having different etiologies and evolution. A common aspect of these pathologies is the development of acute or chronic neuroinflammation. MMPs play an integral part in determining the result of neuroinflammation, in some cases turning its beneficial outcome into a harmful one. This review summarizes the most relevant studies concerning the physiology of MMPs, highlighting their involvement in both the developing and mature CNS, in long-lasting and acute brain diseases and, finally, in nervous system repair. Recently, a concerted effort has been made in identifying therapeutic strategies for major brain diseases by targeting MMP activities. However, from this revision of the literature appears clear that MMPs have multifaceted functional characteristics, which modulate physiological processes in multiple ways and with multiple consequences. Therefore, when choosing MMPs as possible targets, great care must be taken to evaluate the delicate balance between their activation and inhibition and to determine at which stage of the disease and at what level they become active in order maximize chances of success.

APOE Genotype Alters Immunoglobulin Subtypes in Knock-In Mice

Apolipoprotein E (APOE) alleles are strongly related to the risk of Alzheimer's disease (AD). APOE genotype also affects inflammatory processes in response to damage. We tested whether APOE genotype affected the levels of specific immunoglobulins in healthy, uninfected APOE knock-in mice. We measured specific immunoglobulins in brain, spleen, and plasma. Levels of total IgG in brain and spleen were highest in APOE-ɛ3 mice, significantly higher than in APOE-ɛ2 and APOE-ɛ4 mice; no differences were observed for levels of total IgG in plasma. We also measured specific subtypes of IgG. IgG1 was only detectable in plasma and did not differ by APOE genotype. IgG3 was detectable in plasma and spleen, and also did not differ by APOE genotype. IgG2b showed the same pattern as levels of total IgG by APOE genotype, with the highest levels of IgG2b in brain, spleen, and plasma of APOE-ɛ3 mice. IgG2a showed an entirely different pattern, with significantly higher levels in spleen and plasma of APOE-ɛ4 mice compared to APOE-ɛ2 and APOE-ɛ3 mice. We also measured IgM and IgA in spleens and plasma of these mice. In spleen, APOE-ɛ4 mice had the lowest IgA levels and the highest levels of IgM; both being significantly different from APOE-ɛ2 mice. In total, murine IgG2a and IgM were highest in APOE-ɛ4 mice, while total IgG and Ig2b were highest in APOE-ɛ3 mice. These dramatically different distributions of immunoglobulins could allow for human AD risk biomarkers based on specific immunoglobulin subtypes.

Modulating the Immune Response Towards a Neuroregenerative Peri-injury Milieu After Cerebral Hemorrhage

Cerebral hemorrhages account for 15-20 % of stroke sub-types and have very poor prognoses. The mortality rate for cerebral hemorrhage patients is between 40 and 50 %, of which at least half of the deaths occur within the first 2 days, and 75 % of survivors are incapable of living independently after 1 year. Current emergency interventions involve lowering blood pressure and reducing intracranial pressure by controlled ventilations or, in the worst case scenarios, surgical intervention. Some hemostatic and coagulatherapeutic interventions are being investigated, although a few that were promising in experimental studies have failed in clinical trials. No significant immunomodulatory intervention, however, exists for clinical management of cerebral hemorrhage. The inflammatory response following cerebral hemorrhage is particularly harmful in the acute stage because blood-brain barrier disruption is amplified and surrounding tissue is destroyed by secreted proteases and reactive oxygen species from infiltrated leukocytes. In this review, we discuss both the destructive and regenerative roles the immune response play following cerebral hemorrhage and focus on microglia, macrophages, and T-lymphocytes as the primary agents directing the response. Microglia, macrophages, and T-lymphocytes each have sub-types that significantly influence the over-arching immune response towards either a pro-inflammatory, destructive, or an anti-inflammatory, regenerative, state. Both pre-clinical and clinical studies of cerebral hemorrhages that selectively target these immune cells are reviewed and we suggest immunomodulatory therapies that reduce inflammation, while augmenting neural repair, will improve overall cerebral hemorrhage outcomes.

Variable neuroendocrine-immune dysfunction in individuals with unfavorable outcome after severe traumatic brain injury

Bidirectional communication between the immune and neuroendocrine systems is not well understood in the context of traumatic brain injury (TBI). The purpose of this study was to characterize relationships between cerebrospinal fluid (CSF) cortisol and inflammation after TBI, and to determine how these relationships differ by outcome. CSF samples were collected from 91 subjects with severe TBI during days 0-6 post-injury, analyzed for cortisol and inflammatory markers, and compared to healthy controls (n=13 cortisol, n=11 inflammatory markers). Group-based trajectory analysis (TRAJ) delineated subpopulations with similar longitudinal CSF cortisol profiles (high vs. low cortisol). Glasgow Outcome Scale (GOS) scores at 6months served as the primary outcome measure reflecting global outcome. Inflammatory markers that displayed significant bivariate associations with both GOS and cortisol TRAJ (interleukin [IL]-6, IL-10, soluble Fas [sFas], soluble intracellular adhesion molecule [sICAM]-1, and tumor necrosis factor alpha [TNF]-α) were used to generate a cumulative inflammatory load score (ILS). Subsequent analysis revealed that cortisol TRAJ group membership mediated ILS effects on outcome (indirect effect estimate=-0.253, 95% CI (-0.481, -0.025), p=0.03). Correlational analysis between mean cortisol levels and ILS were examined separately within each cortisol TRAJ group and by outcome. Within the low cortisol TRAJ group, subjects with unfavorable 6-month outcome displayed a negative correlation between ILS and mean cortisol (r=-0.562, p=0.045). Conversely, subjects with unfavorable outcome in the high cortisol TRAJ group displayed a positive correlation between ILS and mean cortisol (r=0.391, p=0.006). Our results suggest that unfavorable outcome after TBI may result from dysfunctional neuroendocrine-immune communication wherein an adequate immune response is not mounted or, alternatively, neuroinflammation is prolonged. Importantly, the nature of neuroendocrine-immune dysfunction differs between cortisol TRAJ groups. These results present a novel biomarker-based index from which to discriminate outcome and emphasize the need for evaluating tailored treatments targeting inflammation early after injury.

Neuropathic pain: role of inflammation, immune response, and ion channel activity in central injury mechanisms

Neuropathic pain (NP) is a significant and disabling clinical problem with very few therapeutic treatment options available. A major priority is to identify the molecular mechanisms responsible for NP. Although many seemingly relevant pathways have been identified, more research is needed before effective clinical interventions can be produced. Initial insults to the nervous system, such as spinal cord injury (SCI), are often compounded by secondary mechanisms such as inflammation, the immune response, and the changing expression of receptors and ion channels. The consequences of these secondary effects myriad and compound those elicited by the primary injury. Chronic NP syndromes following SCI can greatly complicate the clinical treatment of the primary injury and result in high comorbidity. In this review, we will describe physiological outcomes associated with SCI along with some of the mechanisms known to contribute to chronic NP development.

(R)-(+)-α-lipoic acid protected NG108-15 cells against H₂O₂-induced cell death through PI3K-Akt/GSK-3β pathway and suppression of NF-κβ-cytokines

Alpha-lipoic acid, a potent antioxidant with multifarious pharmacological benefits has been reported to be neuroprotective in several neuronal models and used to treat neurological disorders such as Alzheimer's disease. Nonetheless, conclusive mechanisms of alpha-lipoic acid for its protective effects particularly in NG108-15 cells have never been investigated. In this study, the intricate neuroprotective molecular mechanisms by (R)-(+)-alpha-lipoic acid (R-LA) against H2O2-induced cell death in an in vitro model of neurodegeneration were elucidated. Pretreatment with R-LA (2 hours) significantly increased NG108-15 cell viability as compared to H2O2-treated cells and mitigated the induction of apoptosis as evidenced by Hoechst 33342/propidium iodide staining. R-LA (12.5-50 μM) aggrandized the reduced glutathione over glutathione disulfide ratio followed by a reduction in the intracellular reactive oxygen species level and an increase in mitochondrial membrane potential following H2O2 exposure. Moreover, pretreatment with R-LA stimulated the activation of PI3K-Akt through mTORC1 and mTORC2 components (mTOR, rictor and raptor) and production of antiinflammatory cytokine, IL-10 which led to the inactivation of glycogen synthase kinase-3β (GSK-3β) and reduction of both Bax/Bcl2 and Bax/Bcl-xL ratios, accompanied by inhibition of the cleaved caspase-3. Additionally, this observation was preceded by the suppression of NF-κβ p65 translocation and production of proinflammatory cytokines (IL-6 and TNF-α). The current findings accentuate new mechanistic insight of R-LA against apoptogenic and brain inflammatory factors in a neuronal model. These results further advocate the therapeutic potential of R-LA for the treatment of neurodegenerative diseases.

Osteopontin expression in acute immune response mediates hippocampal synaptogenesis and adaptive outcome following cortical brain injury

Traumatic brain injury (TBI) produces axotomy, deafferentation and reactive synaptogenesis. Inflammation influences synaptic repair, and the novel brain cytokine osteopontin (OPN) has potential to support axon regeneration through exposure of its integrin receptor binding sites. This study explored whether OPN secretion and proteolysis by matrix metalloproteinases (MMPs) mediate the initial degenerative phase of synaptogenesis, targeting reactive neuroglia to affect successful repair. Adult rats received unilateral entorhinal cortex lesion (UEC) modeling adaptive synaptic plasticity. Over the first week postinjury, hippocampal OPN protein and mRNA were assayed and histology was performed. At 1-2d, OPN protein increased up to 51 fold, and was localized within activated, mobilized glia. OPN transcript also increased over 50 fold, predominantly within reactive microglia. OPN fragments known to be derived from MMP proteolysis were elevated at 1d, consistent with prior reports of UEC glial activation and enzyme production. Postinjury minocycline immunosuppression attenuated MMP-9 gelatinase activity, which was correlated with the reduction of neutrophil gelatinase-associated lipocalin (LCN2) expression, and reduced OPN fragment generation. The antibiotic also attenuated removal of synapsin-1 positive axons from the deafferented zone. OPN KO mice subjected to UEC had similar reduction of hippocampal MMP-9 activity, as well as lower synapsin-1 breakdown over the deafferented zone. MAP1B and N-cadherin, surrogates of cytoarchitecture and synaptic adhesion, were not affected. OPN KO mice with UEC exhibited time dependent cognitive deficits during the synaptogenic phase of recovery. This study demonstrates that OPN can mediate immune response during TBI synaptic repair, positively influencing synapse reorganization and functional recovery.

Hyperbaric oxygen therapy in acute ischemic stroke: a review

Stroke, also known as cerebrovascular disease, is a common and serious neurological disease, which is also the fourth leading cause of death in the United States so far. Hyperbaric medicine, as an emerging interdisciplinary subject, has been applied in the treatment of cerebral vascular diseases since the 1960s. Now it is widely used to treat a variety of clinical disorders, especially hypoxia-induced disorders. However, owing to the complex mechanisms of hyperbaric oxygen (HBO) treatment, the therapeutic time window and the undefined dose as well as some common clinical side effects (such as middle ear barotrauma), the widespread promotion and application of HBO was hindered, slowing down the hyperbaric medicine development. In August 2013, the US Food and Drug Administration declared artery occlusion as one of the 13 specific indications for HBO therapy. This provides opportunities, to some extent, for the further development of hyperbaric medicine. Currently, the mechanisms of HBO therapy for ischemic stroke are still not very clear. This review focuses on the potential mechanisms of HBO therapy in acute ischemic stroke as well as the time window.

Cerebroprotective action of angiotensin peptides in stroke

The goal of the present review is to examine the evidence for beneficial actions of manipulation of the RAS (renin-angiotensin system) in stroke, with particular focus on Ang-(1-7) [angiotensin-(1-7)] and its receptor Mas. The RAS appears to be highly involved in the multifactorial pathophysiology of stroke. Blocking the effects of AngII (angiotensin II) at AT1R (AngII type 1 receptor), through the use of commonly prescribed ACE (angiotensin-converting enzyme) inhibitors or AT1R blockers, has been shown to have therapeutic effects in both ischaemic and haemorrhagic stroke. In contrast with the deleterious actions of over activation of AT1R by AngII, stimulation of AT2Rs (AngII type 2 receptors) in the brain has been demonstrated to elicit beneficial effects in stroke. Likewise, the ACE2/Ang-(1-7)/Mas axis of the RAS has been shown to have therapeutic effects in stroke when activated, countering the effects of the ACE/AngII/AT1R axis. Studies have demonstrated that activating this axis in the brain elicits beneficial cerebral effects in rat models of ischaemic stroke, and we have also demonstrated the cerebroprotective potential of this axis in haemorrhagic stroke using stroke-prone spontaneously hypertensive rats and collagenase-induced striatal haemorrhage. The mechanism of cerebroprotection elicited by ACE2/Ang-(1-7)/Mas activation includes anti-inflammatory effects within the brain parenchyma. The major hurdle to overcome in translating these results to humans is devising strategies to activate the ACE2/Ang-(1-7)/Mas cerebroprotective axis using post-stroke treatments that can be administered non-invasively.

Comparison of the effect of minocycline and simvastatin on functional recovery and gene expression in a rat traumatic brain injury model

The goal of this study was to compare the effects of minocycline and simvastatin on functional recovery and brain gene expression after a cortical contusion impact (CCI) injury. Dosage regimens were designed to provide serum concentrations in a rat model in the range obtained with clinically approved doses; minocycline 60 mg/kg q12h and simvastatin 10 mg/kg q12h for 72 h. Functional recovery was assessed using motor and spatial learning tasks and neuropathological measurements. Microarray-based transcriptional profiling was used to determine the effect on gene expression at 24 h, 72 h, and 7 days post-CCI. Gene Ontology analysis (GOA) was used to evaluate the effect on relevant biological pathways. Both minocycline and simvastatin improved fine motor function, but not gross motor or cognitive function. Minocycline modestly decreased lesion size with no effect of simvastatin. At 24 h post-CCI, GOA identified a significant effect of minocycline on chemotaxis, blood circulation, immune response, and cell to cell signaling pathways. Inflammatory pathways were affected by minocycline only at the 72 h time point. There was a minimal effect of simvastatin on gene expression 24 h after injury, with increasing effects at 72 h and 7 days. GOA identified a significant effect of simvastatin on inflammatory response at 72 h and 7 days. In conclusion, treatment with minocycline and simvastatin resulted in significant effects on gene expression in the brain reflecting adequate brain penetration without producing significant neurorestorative effects.

Increased levels of neurotrophins in the cerebrospinal fluid of children with Epstein-Barr virus meningoencephalitis

OBJECTIVE

The aim of this study was to evaluate the expression of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in the cerebrospinal fluid (CSF) of children with Epstein-Barr virus (EBV)-induced meningoencephalitis (ME) in order to establish a possible correlation with laboratory findings and neurological manifestations.

METHODS

A prospective observational clinical study was performed on 10 children with viral ME, five of them with EBV-induced ME. As controls, we used CSF samples collected from children admitted with febrile seizures. Neurotrophin levels were measured using an enzyme immunoassay.

RESULTS

Significantly higher levels of BDNF and NGF were detected in all patients with viral ME compared to controls. Moreover, in patients with EBV-induced ME, the neurotrophin levels were higher than in those with other viral ME. Of note, in children with EBV-induced ME, we found a significant correlation between neurotrophic factor levels and the number of lymphocytes in the CSF (p<0.001). In these patients we also found a significant correlation between BDNF expression and the blood platelet count (p<0.001). Interestingly, two patients with EBV-induced ME showed a correlation between neurotrophin increase and persistent brain abnormalities, such as prolonged alteration of mental status, psychomotor agitation, and athetosis.

CONCLUSIONS

Viral ME induces an early and strong increased biosynthesis of neurotrophic factors. This neurotrophin over-expression is likely to play a key role in the mechanisms of neuronal inflammation and in the severity of brain damage, particularly in EBV-induced ME.

Comparison of the effects of erythropoietin and anakinra on functional recovery and gene expression in a traumatic brain injury model

The goal of this study was to compare the effects of two inflammatory modulators, erythropoietin (EPO) and anakinra, on functional recovery and brain gene expression following a cortical contusion impact (CCI) injury. Dosage regimens were designed to provide serum concentrations in the range obtained with clinically approved doses. Functional recovery was assessed using both motor and spatial learning tasks and neuropathological measurements conducted in the cortex and hippocampus. Microarray-based transcriptional profiling was used to determine the effect on gene expression at 24 h, 72 h, and 7 days post-CCI. Ingenuity Pathway Analysis was used to evaluate the effect on relevant functional categories. EPO and anakinra treatment resulted in significant changes in brain gene expression in the CCI model demonstrating acceptable brain penetration. At all three time points, EPO treatment resulted in significantly more differentially expressed genes than anakinra. For anakinra at 24 h and EPO at 24 h, 72 h, and 7 days, the genes in the top 3 functional categories were involved in cellular movement, inflammatory response and cell-to-cell signaling. For EPO, the majority of the genes in the top 10 canonical pathways identified were associated with inflammatory and immune signaling processes. This was true for anakinra only at 24 h post-traumatic brain injury (TBI). The immunomodulation effects of EPO and anakinra did not translate into positive effects on functional behavioral and lesion studies. Treatment with either EPO or anakinra failed to induce significant beneficial effects on recovery of function or produce any significant effects on the prevention of injury induced tissue loss at 30 days post-injury. In conclusion, treatment with EPO or anakinra resulted in significant effects on gene expression in the brain without affecting functional outcome. This suggests that targeting these inflammatory processes alone may not be sufficient for preventing secondary injuries after TBI.

Anti-inflammatory and immunomodulatory mechanisms of mesenchymal stem cell transplantation in experimental traumatic brain injury

Background

Previous studies have shown beneficial effects of mesenchymal stem cell (MSC) transplantation in central nervous system (CNS) injuries, including traumatic brain injury (TBI). Potential repair mechanisms involve transdifferentiation to replace damaged neural cells and production of growth factors by MSCs. However, few studies have simultaneously focused on the effects of MSCs on immune cells and inflammation-associated cytokines in CNS injury, especially in an experimental TBI model. In this study, we investigated the anti-inflammatory and immunomodulatory properties of MSCs in TBI-induced neuroinflammation by systemic transplantation of MSCs into a rat TBI model.

Methods/results

MSCs were transplanted intravenously into rats 2 h after TBI. Modified neurologic severity score (mNSS) tests were performed to measure behavioral outcomes. The effect of MSC treatment on neuroinflammation was analyzed by immunohistochemical analysis of astrocytes, microglia/macrophages, neutrophils and T lymphocytes and by measuring cytokine levels [interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-10, IL-17, tumor necrosis factor-α, interferon-γ, RANTES, macrophage chemotactic protein-1, macrophage inflammatory protein 2 and transforming growth factor-β1] in brain homogenates. The immunosuppression-related factors TNF-α stimulated gene/protein 6 (TSG-6) and nuclear factor-κB (NF-κB) were examined by reverse transcription-polymerase chain reaction and Western blotting. Intravenous MSC transplantation after TBI was associated with a lower density of microglia/macrophages and peripheral infiltrating leukocytes at the injury site, reduced levels of proinflammatory cytokines and increased anti-inflammatory cytokines, possibly mediated by enhanced expression of TSG-6, which may suppress activation of the NF-κB signaling pathway.

Conclusions

The results of this study suggest that MSCs have the ability to modulate inflammation-associated immune cells and cytokines in TBI-induced cerebral inflammatory responses. This study thus offers a new insight into the mechanisms responsible for the immunomodulatory effect of MSC transplantation, with implications for functional neurological recovery after TBI.

Fundamental research progress of mild hypothermia in cerebral protection

Through the years, the clinical application of mild hypothermia has been carried out worldwide and is built from the exploration and cognition of neuroprotection mechanisms by hypothermia. However, within the last decade, extensive and fundamental researches in this area have been conducted. In addition to aspects of the previous findings, scholars have discovered several new contents and uncertain results. This article reviews and summarizes this decade’s progression of mild hypothermia in lowering the cerebral oxygen metabolism, protecting the blood–brain-barrier, regulating the inflammatory response, regulating the excessive release of neurotransmitters, inhibiting calcium overload, and reducing neuronal apoptosis. In many aspects, particularly in regulating inflammatory reverse reaction, various results have been reported and therefore guide scholars to conduct more detailed analysis and investigation in order to discover the inherent theories surrounding the effect of mild hypothermia, and for better clinical services.

Influence of age on brain edema formation, secondary brain damage and inflammatory response after brain trauma in mice

After traumatic brain injury (TBI) elderly patients suffer from higher mortality rate and worse functional outcome compared to young patients. However, experimental TBI research is primarily performed in young animals. Aim of the present study was to clarify whether age affects functional outcome, neuroinflammation and secondary brain damage after brain trauma in mice. Young (2 months) and old (21 months) male C57Bl6N mice were anesthetized and subjected to a controlled cortical impact injury (CCI) on the right parietal cortex. Animals of both ages were randomly assigned to 15 min, 24 h, and 72 h survival. At the end of the observation periods, contusion volume, brain water content, neurologic function, cerebral and systemic inflammation (CD3+ T cell migration, inflammatory cytokine expression in brain and lung, blood differential cell count) were determined. Old animals showed worse neurological function 72 h after CCI and a high mortality rate (19.2%) compared to young (0%). This did not correlate with histopathological damage, as contusion volumes were equal in both age groups. Although a more pronounced brain edema formation was detected in old mice 24 hours after TBI, lack of correlation between brain water content and neurological deficit indicated that brain edema formation is not solely responsible for age-dependent differences in neurological outcome. Brains of old naïve mice were about 8% smaller compared to young naïve brains, suggesting age-related brain atrophy with possible decline in plasticity. Onset of cerebral inflammation started earlier and primarily ipsilateral to damage in old mice, whereas in young mice inflammation was delayed and present in both hemispheres with a characteristic T cell migration pattern. Pulmonary interleukin 1β expression was up-regulated after cerebral injury only in young, not aged mice. The results therefore indicate that old animals are prone to functional deficits and strong ipsilateral cerebral inflammation without major differences in morphological brain damage compared to young.

Indomethacin protects rats from neuronal damage induced by traumatic brain injury and suppresses hippocampal IL-1β release through the inhibition of Nogo-A expression

BACKGROUND

Nogo-A is a member of the reticulon family of membrane-associated proteins and plays an important role in axonal remodeling. The present study aimed to investigate alterations in Nogo-A expression following traumatic brain injury (TBI)-induced inflammation and neuronal damage.

METHODS

A weight-drop device was used to deliver a standard traumatic impact to rats. Western blot, RT-PCR and ELISA were used to analyze the expression of Nogo-A and IL-1β. Nogo-A antisense, and an irrelevant control oligonucleotide was intracerebroventricularly infused. We also performed H & E staining and luxol fast blue staining to evaluate the neuronal damage and demyelination resulting from TBI and various treatments.

RESULTS

Based on RT-PCR and western blot analyses, the expression of Nogo-A was found to be significantly upregulated in the hippocampus beginning eight hours after TBI. In addition, TBI caused an apparent elevation in IL-1β levels and severe neuronal damage and demyelination in the tested animals. All of the TBI-associated molecular and cellular consequences could be effectively reversed by treating the animals with the anti-inflammatory drug indomethacin. More importantly, the TBI-associated stimulation in the levels of both Nogo-A and IL-1β could be effectively inhibited by a specific Nogo-A antisense oligonucleotide.

CONCLUSIONS

Our findings suggest that the suppression of Nogo-A expression appears to be an early response conferred by indomethacin, which then leads to decreases in the levels of IL-1β and TBI-induced neuron damage.

The role of hepatic stellate cells in the regulation of T-cell function and the promotion of hepatocellular carcinoma

Hepatic stellate cells (HSCs) have immunosuppressive abilities and may be responsible for the occurrence and development of hepatocellular carcinoma (HCC). However, the mechanisms through which HSCs affect T-cell-mediated immune responses remain unclear. The aim of this study was to elucidate these mechanisms. We examined the effect of HSCs on T-cell proliferation and apoptosis, regulatory T cells (Treg cells) and T-cell-mediated cytotoxicity using mixed leukocyte reactions (MLRs). Furthermore, we examined the cytokines present in the supernatant and the effect of this supernatant on the proliferation and migration of cancer cells. Finally, we examined the effect of HSCs on HCC cells in vivo. We found that activated HSCs induced T-cell hyporesponsiveness, accelerated activated T-cell apoptosis, increased the number of Treg cells and inhibited T-cell-mediated cytotoxicity. HSCs also enhanced the expression of some cytokines and promoted the proliferation and migration of cancer cells. Furthermore, activated HSCs were able to induce HCC proliferation and Treg cells expansion in vivo. Activated HSCs may induce T cell anergy, thereby facilitating the immunologic escape of HCC cells.

The role of hepatic stellate cells in the regulation of T-cell function and the promotion of hepatocellular carcinoma

Hepatic stellate cells (HSCs) have immunosuppressive abilities and may be responsible for the occurrence and development of hepatocellular carcinoma (HCC). However, the mechanisms through which HSCs affect T-cell-mediated immune responses remain unclear. The aim of this study was to elucidate these mechanisms. We examined the effect of HSCs on T-cell proliferation and apoptosis, regulatory T cells (Treg cells) and T-cell-mediated cytotoxicity using mixed leukocyte reactions (MLRs). Furthermore, we examined the cytokines present in the supernatant and the effect of this supernatant on the proliferation and migration of cancer cells. Finally, we examined the effect of HSCs on HCC cells in vivo. We found that activated HSCs induced T-cell hyporesponsiveness, accelerated activated T-cell apoptosis, increased the number of Treg cells and inhibited T-cell-mediated cytotoxicity. HSCs also enhanced the expression of some cytokines and promoted the proliferation and migration of cancer cells. Furthermore, activated HSCs were able to induce HCC proliferation and Treg cells expansion in vivo. Activated HSCs may induce T cell anergy, thereby facilitating the immunologic escape of HCC cells.