Interferons in Traumatic Brain and Spinal Cord Injury: Current Evidence for Translational Application

Anti-acetylated-tau immunotherapy is neuroprotective in tauopathy and brain injury

BACKGROUND

Tau is aberrantly acetylated in various neurodegenerative conditions, including Alzheimer's disease, frontotemporal lobar degeneration (FTLD), and traumatic brain injury (TBI). Previously, we reported that reducing acetylated tau by pharmacologically inhibiting p300-mediated tau acetylation at lysine 174 reduces tau pathology and improves cognitive function in animal models.

METHODS

We investigated the therapeutic efficacy of two different antibodies that specifically target acetylated lysine 174 on tau (ac-tauK174). We treated PS19 mice, which harbor the P301S tauopathy mutation that causes FTLD, with anti-ac-tauK174 and measured effects on tau pathology, neurodegeneration, and neurobehavioral outcomes. Furthermore, PS19 mice received treatment post-TBI to evaluate the ability of the immunotherapy to prevent TBI-induced exacerbation of tauopathy phenotypes. Ac-tauK174 measurements in human plasma following TBI were also collected to establish a link between trauma and acetylated tau levels, and single nuclei RNA-sequencing of post-TBI brain tissues from treated mice provided insights into the molecular mechanisms underlying the observed treatment effects.

RESULTS

Anti-ac-tauK174 treatment mitigates neurobehavioral impairment and reduces tau pathology in PS19 mice. Ac-tauK174 increases significantly in human plasma 24 h after TBI, and anti-ac-tauK174 treatment of PS19 mice blocked TBI-induced neurodegeneration and preserved memory functions. Anti-ac-tauK174 treatment rescues alterations of microglial and oligodendrocyte transcriptomic states following TBI in PS19 mice.

CONCLUSIONS

The ability of anti-ac-tauK174 treatment to rescue neurobehavioral impairment, reduce tau pathology, and rescue glial responses demonstrates that targeting tau acetylation at K174 is a promising neuroprotective therapeutic approach to human tauopathies resulting from TBI or genetic disease.

BM-MSC-Loaded Graphene-Collagen Cryogels Ameliorate Neuroinflammation in a Rat Spinal Cord Injury Model

A major obstacle to axonal regeneration following spinal cord injury (SCI) is neuroinflammation mediated by astrocytes and microglial cells. We previously demonstrated that graphene-based collagen hydrogels alone can decrease neuroinflammation in SCI. Their regenerative potential, however, is poorly understood and incomplete. Furthermore, stem cells have demonstrated both neuroprotective and regenerative properties in spinal cord regeneration, although there are constraints connected with the application of stem cell-based therapy. In this study, we have analyzed the regeneration capability of human bone marrow mesenchymal stem cell (BM-MSC)-loaded graphene-cross-linked collagen cryogels (Gr-Col) in a thoracic (T10-T11) hemisection model of SCI. Our study found that BM-MSC-loaded Gr-Col improves axonal regeneration, reduces neuroinflammation by decreasing astrocyte reactivity, and promotes M2 macrophage polarization. BM-MSC-loaded-Gr-Col demonstrated enhanced regenerative potential compared to Gr-Col and the injury group control. Next-generation sequencing (NGS) analysis revealed that BM-MSC-loaded-Gr-Col modulates the JAK2-STAT3 pathway, thus decreasing the reactive and scar-forming astrocyte phenotype. The decrease in neuroinflammation in the BM-MSC-loaded-Gr-Col group is attributed to the modulation of Notch/Rock and STAT5a/b and STAT6 signaling. Overall, Gene Set Enrichment Analysis suggests the promising role of BM-MSC-loaded-Gr-Col in promoting axonal regeneration after SCI by modulating molecular pathways such as the PI3/Akt pathway, focal adhesion kinase, and various inflammatory pathways.

Identification of age-specific biomarkers of spinal cord injury: A bioinformatics analysis of young and aged mice models

BACKGROUND

Spinal cord injury (SCI) is a debilitating event that often results in long-term physical damage, disability, and a significant impact on a patient's quality of life. Past research has noted an age-dependent decline in regeneration post-SCI. This study seeks to identify potential biomarkers and enriched pathways in young and aged SCI mouse models.

METHODS

We retrieved the microarray data of spinal cord samples from SCI mice and control mice from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using the R software and the Linear Models for Microarray Data (limma) package. The Gene Set Enrichment Analysis (GSEA) determined enrichment differences among gene sets. The Weighted Gene Co-expression Network Analysis (WGCNA) pinpointed clinically significant modules and hub genes in SCI. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was employed to uncover significantly related pathways of crucial genes in SCI.

RESULTS

We found 2560 DEGs in the young SCI group, comprised of 1733 upregulated RNAs and 827 downregulated RNAs. In the aged SCI group, 3048 DEGs were revealed including 1856 upregulated and 1192 downregulated genes. The GSEA revealed 12 enriched signaling pathways in the young SCI group, such as IL6/JAK/STAT3 signaling, interferon alpha response, and interferon gamma response, and 21 signaling pathways in the aged SCI group such as IL6/JAK/STAT3 signaling, E2F targets, and angiogenesis-related pathways. The WGCNA identified the turquoise module as significantly associated with the clinical traits of both young and aged SCI, and revealed 3181 hub genes. Ultimately, 1858 significant genes in SCI were found, with associated signaling pathways including epithelial-mesenchymal transition (EMT), interferon gamma response, and KARS signaling.

CONCLUSION

Our study explored the RNA expression patterns and enriched signaling pathways in young and aged SCI mice. These findings may provide potential biomarkers for targeted SCI therapy.

Relationship between inflammatory-related cytokines with aortic dissection

Aortic dissection, characterized by severe intramural hematoma formation and acute endometrial rupture, is caused by excessive bleeding within the aortic wall or a severe tear within the intimal layer of the aorta, which subsequently promotes the separation or dissection in the layers of the aortic wall. Epidemiological surveys showed that aortic dissection was most observed among those patients from 55 to 80 years of age, with a prevalence of approximately 40 cases per 100,000 individuals per year, posing serious risks to future health and leading to high mortality. Other risk factors of aortic dissection progression contained dyslipidemia, hypertension, and genetic disorders, such as Marfan syndrome. Currently, emerging evidence indicates the pathological progression of aortic dissection is significantly complicated, which is correlated with the aberrant infiltration of pro-inflammatory cells into the aortic wall, subsequently facilitating the apoptosis of vascular smooth muscle cells (VSMCs) and inducing the aberrant expression of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interferon (IF). Other pro-inflammatory-related cytokines, including the colony-stimulating factor (CSF), chemotactic factor, and growth factor (GF), played an essential function in facilitating aortic dissection. Multiple studies focused on the important relationship between pro-inflammatory cytokines and aortic dissection, which could deepen the understanding of aortic dissection and further guide the therapeutic strategies in clinical practice. The present review elucidated pro-inflammatory cytokines' functions in modulating the risk of aortic dissection are summarized. Moreover, the emerging evidence that aimed to elucidate the potential mechanisms wherebyvarious pro-inflammatory cytokines affected the pathological development of aortic dissection was also listed.

Selective Inhibition of Soluble Tumor Necrosis Factor Alters the Neuroinflammatory Response following Moderate Spinal Cord Injury in Mice

Clinical and animal model studies have implicated inflammation and glial and peripheral immune cell responses in the pathophysiology of spinal cord injury (SCI). A key player in the inflammatory response after SCI is the pleiotropic cytokine tumor necrosis factor (TNF), which exists both in both a transmembrane (tmTNF) and a soluble (solTNF) form. In the present study, we extend our previous findings of a therapeutic effect of topically blocking solTNF signaling after SCI for three consecutive days on lesion size and functional outcome to study the effect on spatio-temporal changes in the inflammatory response after SCI in mice treated with the selective solTNF inhibitor XPro1595 and compared to saline-treated mice. We found that despite comparable TNF and TNF receptor levels between XPro1595- and saline-treated mice, XPro1595 transiently decreased pro-inflammatory interleukin (IL)-1β and IL-6 levels and increased pro-regenerative IL-10 levels in the acute phase after SCI. This was complemented by a decrease in the number of infiltrated leukocytes (macrophages and neutrophils) in the lesioned area of the spinal cord and an increase in the number of microglia in the peri-lesion area 14 days after SCI, followed by a decrease in microglial activation in the peri-lesion area 21 days after SCI. This translated into increased myelin preservation and improved functional outcomes in XPro1595-treated mice 35 days after SCI. Collectively, our data suggest that selective targeting of solTNF time-dependently modulates the neuroinflammatory response by favoring a pro-regenerative environment in the lesioned spinal cord, leading to improved functional outcomes.

The role of STING signaling in central nervous system infection and neuroinflammatory disease

The cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthase-Stimulator of Interferon Genes (cGAS-STING) pathway is a critical innate immune mechanism for detecting the presence of double-stranded DNA (dsDNA) and prompting a robust immune response. Canonical cGAS-STING activation occurs when cGAS, a predominantly cytosolic pattern recognition receptor, binds microbial DNA to promote STING activation. Upon STING activation, transcription factors enter the nucleus to cause the production of Type I interferons, inflammatory cytokines whose primary function is to prime the host for viral infection by producing a number of antiviral interferon-stimulated genes. While the pathway was originally described in viral infection, more recent studies have implicated cGAS-STING signaling in a number of different contexts, including autoimmune disease, cancer, injury, and neuroinflammatory disease. This review focuses on how our understanding of the cGAS-STING pathway has evolved over time with an emphasis on the role of STING-mediated neuroinflammation and infection in the nervous system. We discuss recent findings on how STING signaling contributes to the pathology of pain, traumatic brain injury, and stroke, as well as how mitochondrial DNA may promote STING activation in common neurodegenerative diseases. We conclude by commenting on the current knowledge gaps that should be filled before STING can be an effective therapeutic target in neuroinflammatory disease. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology Infectious Diseases > Molecular and Cellular Physiology Immune System Diseases > Molecular and Cellular Physiology.

γδ T cells recruitment and local proliferation in brain parenchyma benefit anti-neuroinflammation after cerebral microbleeds

Background

Cerebral microbleeds (CMBs) are an early sign of many neurological disorders and accompanied by local neuroinflammation and brain damage. As important regulators of immune response and neuroinflammation, the biological behavior and role of γδ T cells after CMBs remain largely unknown.

Methods

We made a spot injury of microvessel in the somatosensory cortex to mimic the model of CMBs by two-photon laser and in vivo tracked dynamical behaviors of γδ T cells induced by CMBs using TCR-δGFP transgenic mice. Biological features of γδ T cells in the peri-CMBs parenchyma were decoded by flow cytometry and Raman spectra. In wildtype and γδ T cell-deficient mice, neuroinflammation and neurite degeneration in the peri-CMBs cortex were studied by RNAseq, immunostaining and in vivo imaging respectively.

Results

After CMBs, γδ T cells in the dural vessels were tracked to cross the meningeal structure and invade the brain parenchyma in a few days, where the division process of γδ T cells were captured. Parenchymal γδ T cells were highly expressed by CXCR6 and CCR6, similar to meningeal γδ T cells, positive for IL-17A and Ki67 (more than 98%), and they contained abundant substances for energy metabolism and nucleic acid synthesis. In γδ T cell-deficient mice, cortical samples showed the upregulation of neuroinflammatory signaling pathways, enhanced glial response and M1 microglial polarization, and earlier neuronal degeneration in the peri-CMBs brain parenchyma compared with wildtype mice.

Conclusion

CMBs induce the accumulation and local proliferation of γδ T cells in the brain parenchyma, and γδ T cells exert anti-neuroinflammatory and neuroprotective effects at the early stage of CMBs.

Driving axon regeneration by orchestrating neuronal and non-neuronal innate immune responses via the IFNγ-cGAS-STING axis

The coordination mechanism of neural innate immune responses for axon regeneration is not well understood. Here, we showed that neuronal deletion of protein tyrosine phosphatase non-receptor type 2 sustains the IFNγ-STAT1 activity in retinal ganglion cells (RGCs) to promote axon regeneration after injury, independent of mTOR or STAT3. DNA-damage-induced cGAMP synthase (cGAS)-stimulator of interferon genes (STINGs) activation is the functional downstream signaling. Directly activating neuronal STING by cGAMP promotes axon regeneration. In contrast to the central axons, IFNγ is locally translated in the injured peripheral axons and upregulates cGAS expression in Schwann cells and infiltrating blood cells to produce cGAMP, which promotes spontaneous axon regeneration as an immunotransmitter. Our study demonstrates that injured peripheral nervous system (PNS) axons can direct the environmental innate immune response for self-repair and that the neural antiviral mechanism can be harnessed to promote axon regeneration in the central nervous system (CNS).

Molecular Mechanisms in the Vascular and Nervous Systems following Traumatic Spinal Cord Injury

Traumatic spinal cord injury (SCI) induces various complex pathological processes that cause physical impairment and psychological devastation. The two phases of SCI are primary mechanical damage (the immediate result of trauma) and secondary injury (which occurs over a period of minutes to weeks). After the mechanical impact, vascular disruption, inflammation, demyelination, neuronal cell death, and glial scar formation occur during the acute phase. This sequence of events impedes nerve regeneration. In the nervous system, various extracellular secretory factors such as neurotrophic factors, growth factors, and cytokines are involved in these events. In the vascular system, the blood-spinal cord barrier (BSCB) is damaged, allowing immune cells to infiltrate the parenchyma. Later, endogenous angiogenesis is promoted during the subacute phase. In this review, we describe the roles of secretory factors in the nervous and vascular systems following traumatic SCI, and discuss the outcomes of their therapeutic application in traumatic SCI.

Lipopolysaccharide distinctively alters human microglia transcriptomes to resemble microglia from Alzheimer's disease mouse models

Alzheimer's disease (AD) is the most common form of dementia, and risk-influencing genetics implicates microglia and neuroimmunity in the pathogenesis of AD. Induced pluripotent stem cell (iPSC)-derived microglia (iPSC-microglia) are increasingly used as a model of AD, but the relevance of historical immune stimuli to model AD is unclear. We performed a detailed cross-comparison over time on the effects of combinatory stimulation of iPSC-microglia, and in particular their relevance to AD. We used single-cell RNA sequencing to measure the transcriptional response of iPSC-microglia after 24 h and 48 h of stimulation with prostaglandin E2 (PGE2) or lipopolysaccharide (LPS)+interferon gamma (IFN-γ), either alone or in combination with ATPγS. We observed a shared core transcriptional response of iPSC-microglia to ATPγS and to LPS+IFN-γ, suggestive of a convergent mechanism of action. Across all conditions, we observed a significant overlap, although directional inconsistency to genes that change their expression levels in human microglia from AD patients. Using a data-led approach, we identify a common axis of transcriptomic change across AD genetic mouse models of microglia and show that only LPS provokes a transcriptional response along this axis in mouse microglia and LPS+IFN-γ in human iPSC-microglia. This article has an associated First Person interview with the first author of the paper.

Plasma Cytokines Level and Spinal Cord MRI Predict Clinical Outcome in a Rat Glial Scar Cryoinjury Model

Traumatic injury of the spinal cord is still one of the most challenging problems in the neurosurgical practice. Despite a long history of implementation of translational medicine in the field of spinal cord injury (SCI), it remains one of the most frequent causes of human disability and a critical situation for world healthcare systems. Here, we used our rat model of the of unilateral controlled SCI induced by a cryoinjury, which consistently reproduces glial scarring and posttraumatic cyst formation, and specifically evaluated histological, bioimaging and cytokine data. We propose a 10-grade scoring scale, which can objectively estimate the extent of damage of the experimental SCI according to the magnetic resonance imaging (MRI) results. It provides a homogeneous and reliable visual control of the dynamics of the posttraumatic processes, which makes it possible to clearly distinguish the extent of early damage, the formation of glial scars and the development of posttraumatic syringomyelic cysts. The concentration of cytokines and chemokines in the plasma following the experimental SCI increased up to two orders of magnitude in comparison with intact animals, suggesting that a traumatic injury of the spinal cord was accompanied by a remarkable cytokine storm. Our data suggested that the levels of IL-1α, IL-1β, TNFα, GRO/KC, G-CSF, IFNγ and IL-13 may be considered as a reliable prognostic index for SCI. Finally, we demonstrated that MRI together with plasma cytokines level directly correlated and reliably predicted the clinical outcome following SCI. The present study brings novel noninvasive and intravital methods for the evaluation of the therapeutic efficacy of SCI treatment protocols, which may be easily translated into the clinical practice.

Multi-Omic Admission-Based Prognostic Biomarkers Identified by Machine Learning Algorithms Predict Patient Recovery and 30-Day Survival in Trauma Patients

Admission-based circulating biomarkers for the prediction of outcomes in trauma patients could be useful for clinical decision support. It is unknown which molecular classes of biomolecules can contribute biomarkers to predictive modeling. Here, we analyzed a large multi-omic database of over 8500 markers (proteomics, metabolomics, and lipidomics) to identify prognostic biomarkers in the circulating compartment for adverse outcomes, including mortality and slow recovery, in severely injured trauma patients. Admission plasma samples from patients (n = 129) enrolled in the Prehospital Air Medical Plasma (PAMPer) trial were analyzed using mass spectrometry (metabolomics and lipidomics) and aptamer-based (proteomics) assays. Biomarkers were selected via Least Absolute Shrinkage and Selection Operator (LASSO) regression modeling and machine learning analysis. A combination of five proteins from the proteomic layer was best at discriminating resolvers from non-resolvers from critical illness with an Area Under the Receiver Operating Characteristic curve (AUC) of 0.74, while 26 multi-omic features predicted 30-day survival with an AUC of 0.77. Patients with traumatic brain injury as part of their injury complex had a unique subset of features that predicted 30-day survival. Our findings indicate that multi-omic analyses can identify novel admission-based prognostic biomarkers for outcomes in trauma patients. Unique biomarker discovery also has the potential to provide biologic insights.

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

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

Clinical Value of Inflammatory Cytokines in Patients with Aneurysmal Subarachnoid Hemorrhage

Background

Inflammation is closely associated with prognosis in patients with aneurysmal subarachnoid hemorrhage (aSAH), which is orchestrated by inflammatory cytokines. Therefore, this study aimed to investigate the levels of inflammatory cytokines in the early stage of aSAH and their predictive value for prognosis.

Methods

In this retrospective study, 206 patients with aSAH were recruited and assigned to a severe group (WFNS grade ≥ 4) and a mild group (WFNS grade < 4) according to the severity of patients on admission. Flow cytometry was performed to detect the levels of 12 inflammatory cytokines in the serum of patients. Then, patients were grouped into a poor prognosis group (mRS score ≥ 4) and a good prognosis group (mRS score < 4) based on their prognosis after 3 months of discharge to compare the relationship between cytokines and prognosis. Propensity score matching (PSM) was utilized to control confounding factors. The correlation between inflammatory factors and prognosis was determined using Spearman correlation, and the predictive efficacy of inflammatory factors was tested by a receiver operating characteristic curve.

Results

Serum IL-1β, IL-5, IL-6, IL-8, IL-10, IFN-γ, and TNF-α levels were significantly higher in the mild group than in the severe group and in the poor prognosis group than in the good prognosis group. After PSM, the differences in IL-1β, IL-5, IFN-α, and IFN-γ levels disappeared between the two groups, whereas IL-2, IL-6, IL-8, IL-10, and TNF-α levels remained higher in the poor prognosis group than in the good prognosis group. Additionally, IL-2, IL-6, IL-8, and IL-10 levels were positively correlated with mRS scores. Moreover, the predictive value was found to be the highest for IL-6 and the lowest for TNF-α.

Conclusion

Inflammation degree was related to the severity of aSAH. Inflammatory markers, including IL-6, IL-10, IL-8, IL-2, and TNF-α, might predict the poor prognosis of aSAH.

CCR2 deficiency alters activation of microglia subsets in traumatic brain injury

In traumatic brain injury (TBI), a diversity of brain resident and peripherally derived myeloid cells have the potential to worsen damage and/or to assist in healing. We define the heterogeneity of microglia and macrophage phenotypes during TBI in wild-type (WT) mice and Ccr2^−/− mice, which lack macrophage influx following TBI and are resistant to brain damage. We use unbiased single-cell RNA sequencing methods to uncover 25 microglia, monocyte/macrophage, and dendritic cell subsets in acute TBI and normal brains. We find alterations in transcriptional profiles of microglia subsets in Ccr2^−/− TBI mice compared to WT TBI mice indicating that infiltrating monocytes/macrophages influence microglia activation to promote a type I IFN response. Preclinical pharmacological blockade of hCCR2 after injury reduces expression of IFN-responsive gene, Irf7, and improves outcomes. These data extend our understanding of myeloid cell diversity and crosstalk in brain trauma and identify therapeutic targets in myeloid subsets.

By single-cell RNA sequencing of traumatically injured and normal brains from wild-type and Ccr2^−/− mice, Somebang et al. define microglia, macrophage, and dendritic cell phenotypes in TBI. Targeting mouse and/or human CCR2 reduces specific TBI brain CNS myeloid compartments, dampens type I interferon responses, and improves cognition after TBI.

T-cell infiltration, contribution and regulation in the central nervous system post-traumatic injury

T cells participate in the repair process and immune response in the CNS post-traumatic injury and play both a beneficial and harmful role. Together with nerve cells and other immune cells, they form a microenvironment in the CNS post-traumatic injury. The repair of traumatic CNS injury is a long-term process. T cells contribute to the repair of the injury site to influence the recovery. Recently, with the advance of new techniques, such as mass spectrometry-based flow cytometry, modern live-cell imaging, etc, research focusing on T cells is becoming one of the valuable directions for the future therapy of traumatic CNS injury. In this review, we summarized the infiltration, contribution and regulation of T cells in post-traumatic injury, discussed the clinical significance and predicted the future research direction.

Duck Tembusu virus induces stronger cellular responses than Japanese encephalitis virus in primary duck neurons and fibroblasts

Duck Tembusu virus (DTMUV) and Japanese encephalitis virus (JEV) are mosquito-borne flaviviruses. These two viruses infect ducks; however, they show different neurological outcomes. The mechanism of DTMUV- and JEV-induced neuronal death has not been well investigated. In the present study, we examined the differences in the mechanisms involved in virus-induced cell death and innate immune responses between DTMUV KPS54A61 strain and JEV JaGAr-01 strain using primary duck neurons (DN) and duck fibroblasts (CCL-141). DN and CCL-141 were permissive for the infection and replication of these two viruses, which upregulated the expression of innate immunity genes. Both DTMUV and JEV induced cell death via a caspase-3-dependent manner; however, DTMUV triggered more cell death than JEV did in both CCL-141 and DN. These findings suggest that DTMUV infection causes apoptosis in duck neurons and fibroblasts more strongly than JEV. Levels of the mRNA expression of innate immunity-related genes after DTMUV infection were generally higher than levels after JEV infection, suggesting that DTMUV-induced immune response in duck cells may exhibit toxic effect rather than protective effects. This article is protected by copyright. All rights reserved.

Decoding the Transcriptional Response to Ischemic Stroke in Young and Aged Mouse Brain

Ischemic stroke is a well-recognized disease of aging, yet it is unclear how the age-dependent vulnerability occurs and what are the underlying mechanisms. To address these issues, we perform a comprehensive RNA-seq analysis of aging, ischemic stroke, and their interaction in 3- and 18-month-old mice. We assess differential gene expression across injury status and age, estimate cell type proportion changes, assay the results against a range of transcriptional signatures from the literature, and perform unsupervised co-expression analysis, identifying modules of genes with varying response to injury. We uncover downregulation of axonal and synaptic maintenance genetic program, and increased activation of type I interferon (IFN-I) signaling following stroke in aged mice. Together, these results paint a picture of ischemic stroke as a complex age-related disease and provide insights into interaction of aging and stroke on cellular and molecular level.

Acute Inflammation in Traumatic Brain Injury and Polytrauma Patients Using Network Analysis

INTRODUCTION

Traumatic brain injury (TBI) is associated with secondary injury to the central nervous system (CNS) via inflammatory mechanisms. The combination of polytrauma and TBI further exacerbates the inflammatory response to injury; however, combined injury phenomena have not been thoroughly studied. In this study, we examined the inflammatory differences between patients with TBI versus patients with polytrauma, but no TBI (polytrauma). We hypothesize that patients with TBI have a heightened early inflammatory response compared with polytrauma.

METHODS

We conducted a single-center retrospective study of a cohort of patients with polytrauma, who were enrolled in the PROPPR study. These patients had blood samples prospectively collected at eight time points in the first 3 days of admission. Using radiological data to determine TBI, our polytrauma cohort was dichotomized into TBI (n = 30) or polytrauma (n = 54). Inflammatory biomarkers were measured using ELISA. Data across time were compared for TBI versus polytrauma groups using Wilcoxon rank-sum test. Network analysis techniques were used to systematically characterize the inflammatory responses at admission.

RESULTS

Patients with TBI (51.6%) had a higher 30-day mortality compared with polytrauma (16.9%) (P <0.001). Expression levels of IL6, IL8, and CCL2 were elevated from the 2-h through 24-h time points, becoming significant at the 6-h time point (IL6, IL8, and CCL2; P <0.05) (). CSF3 showed a similar pattern, but did not attain significance. TBI and polytrauma networks underwent diverging trends from admission to the 6-h time point.

CONCLUSION

Patients with TBI demonstrated upregulations in proinflammatory cytokines IL6, IL8, and CCL2. Utilizing informatics methods, we were able to identify temporal differences in network trends, as well as uncharacterized cytokines and chemokines in TBI. These data suggest TBI induces a distinct inflammatory response and pathologically heightened inflammatory response in the presence of polytrauma and may propagate worsened patient outcomes including mortality.

Early CSF Biomarkers and Late Functional Outcomes in Spinal Cord Injury. A Pilot Study

Although, biomarkers are regarded as an important tool for monitoring injury severity and treatment efficacy, and for predicting clinical evolution in many neurological diseases and disorders including spinal cord injury, there is still a lack of reliable biomarkers for the assessment of clinical course and patient outcome. In this study, a biological dataset of 60 cytokines/chemokines, growth factorsm and intracellular and extracellular matrix proteins, analyzed in CSF within 24 h of injury, was used for correlation analysis with the clinical dataset of the same patients. A heat map was generated of positive and negative correlations between biomarkers and clinical rating scale scores at discharge, and between biomarkers and changes in clinical scores during the observation period. Using very stringent statistical criteria, we found 10 molecules which correlated with clinical scores at discharge, and five molecules, which correlated with changes in clinical scores. The proposed methodology may be useful for generating hypotheses regarding "predictive" and "treatment effectiveness" biomarkers, thereby suggesting potential candidates for disease-modifying therapies using a "bed-to-bench" approach.

Neuroinflammation after SCI: Current Insights and Therapeutic Potential of Intravenous Immunoglobulin

Traumatic spinal cord injury (SCI) elicits a complex cascade of cellular and molecular inflammatory events. Although certain aspects of the inflammatory response are essential to wound healing and repair, post-SCI inflammation is, on balance, thought to be detrimental to recovery by causing "bystander damage" and the spread of pathology into spared but vulnerable regions of the spinal cord. Much of the research to date has therefore focused on understanding the inflammatory drivers of secondary tissue loss after SCI, to define therapeutic targets and positively modulate this response. Numerous experimental studies have demonstrated that modulation of the inflammatory response to SCI can indeed lead to significant neuroprotection and improved recovery. However, it is now also recognized that broadscale immunosuppression is not necessarily beneficial and may even carry the risk of contributing to the development of serious adverse events. Immune modulation rather than suppression is therefore now considered a more promising approach to target harmful post-traumatic inflammation following a major neurotraumatic event such as SCI. One promising immunomodulatory agent is intravenous immunoglobulin (IVIG), a plasma product that contains mostly immunoglobulin G (IgG) from thousands of healthy donors. IVIG is currently already widely used to treat a range of autoimmune diseases, but recent studies have found that it also holds great promise for treating acute neurological conditions, including SCI. This review provides an overview of the inflammatory response to SCI, immunomodulatory approaches that are currently in clinical trials, proposed mechanisms of action for IVIG therapy, and the putative relevance of these in the context of neurotraumatic events.

Interferon-Gamma and Interleukin-1Beta Enhance the Secretion of Brain-Derived Neurotrophic Factor and Promotes the Survival of Cortical Neurons in Brain Injury

Neuro-inflammation is associated with the production of cytokines, which influence neuronal and glial functions. Although the proinflammatory cytokines interferon-γ (IFN-γ) and interleukin-1Beta (IL-1β) are thought to be the major mediators of neuro-inflammation, their role in brain injury remains ill-defined. The objective of this study was to examine the effect of IFN-γ and IL-1β on survival of cortical neurons in stab wound injury in mice. A stab wound injury was made in the cortex of male BALB/c mice. Injured mice (I) were divide into IFN-γ and IL-1β treatment experiments. Mice in I + IFN-γ group were treated with IFN-γ (ip, 10 µg/kg/day) for 1, 3 and 7 days and mice in I + IL-1β group were treated with 5 IP injection of IL-1β (0.5 µg /12 h). Appropriate control mice were maintained for comparison. Immunostaining of frozen brain sections for astrocytes (GFAP), microglia (Iba-1) and Fluoro-Jade B staining for degenerating neurons were used. Western blotting and ELISA for brain-derived neurotrophic factor (BDNF) were done on the tissues isolated from the injured sites. Results showed a significant increase in the number of both astrocytes and microglia in I + IFN-γ and I + IL-1β groups. There were no significant changes in the number of astrocytes or microglia in noninjury groups (NI) treated with IFN-γ or IL-1β. The number of degenerating neurons significantly decreased in I + IFN-γ and I + IL-1β groups. GFAP and BDNF levels were significantly increased in I + IFN-γ and I + IL-1β groups. Interferon-γ and IL-1β induce astrogliosis, microgliosis, enhance the secretion of BDNF, one of the many neurotrophic factors after brain injury, and promote the survival of cortical neurons in stab wound brain injury.

Cytokine Profile As a Marker of Cell Damage and Immune Dysfunction after Spinal Cord Injury

This study reviews the findings of recent experiments designed to investigate the cytokine profile after a spinal cord injury. The role played by key cytokines in eliciting the cellular response to trauma was assessed. The results of the specific immunopathogenetic interaction between the nervous and immune systems in the immediate and chronic post-traumatic periods are summarized. It was demonstrated that it is reasonable to use the step-by-step approach to the assessment of the cytokine profile after a spinal cord injury and take into account the combination of the pathogenetic and protective components in implementing the regulatory effects of individual cytokines and their integration into the regenerative processes in the injured spinal cord. This allows one to rationally organize treatment and develop novel drugs.

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

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

Sustained in vitro interferon-beta release and in vivo toxicity of PLGA and PEG-PLGA nanoparticles

Interferon-beta-1a (IFN-β-1a) can diminish the symptoms of relapsing-remitting multiple sclerosis. Herein, we prepared sustained drug delivery IFN-β-1a-loaded nanoparticles by a double emulsion solvent evaporation method. Bovine serum albumin (BSA) model drug was used to optimize the preparation of nanoparticles composed of four types of poly(lactic-co-glycolic acid) (PLGA) polymers and two pegylated PLGA (PEG-PLGA) polymers. Via optimization, selected PLGA and PEG-PLGA polymers were able to entrap IFN-β-1a with high encapsulation efficiency (>95%) and low size (145 nm and 163 nm, respectively). In vitro release kinetics of BSA and IFN-β showed similar tendency for PLGA and PEG-PLGA nanoparticles, respectively. Although the drug loaded nanoparticles did not show toxicity in hepatocyte cells, mild toxic effects such as pale kidney and pyelectasis were observed in the in vivo studies.

Interferon-β Plays a Detrimental Role in Experimental Traumatic Brain Injury by Enhancing Neuroinflammation That Drives Chronic Neurodegeneration

DNA damage and type I interferons (IFNs) contribute to inflammatory responses after traumatic brain injury (TBI). TBI-induced activation of microglia and peripherally-derived inflammatory macrophages may lead to tissue damage and neurological deficits. Here, we investigated the role of IFN-β in secondary injury after TBI using a controlled cortical impact model in adult male IFN-β-deficient (IFN-β^-/-) mice and assessed post-traumatic neuroinflammatory responses, neuropathology, and long-term functional recovery. TBI increased expression of DNA sensors cyclic GMP-AMP synthase and stimulator of interferon genes in wild-type (WT) mice. IFN-β and other IFN-related and neuroinflammatory genes were also upregulated early and persistently after TBI. TBI increased expression of proinflammatory mediators in the cortex and hippocampus of WT mice, whereas levels were mitigated in IFN-β^-/- mice. Moreover, long-term microglia activation, motor, and cognitive function impairments were decreased in IFN-β^-/- TBI mice compared with their injured WT counterparts; improved neurological recovery was associated with reduced lesion volume and hippocampal neurodegeneration in IFN-β^-/- mice. Continuous central administration of a neutralizing antibody to the IFN-α/β receptor (IFNAR) for 3 d, beginning 30 min post-injury, reversed early cognitive impairments in TBI mice and led to transient improvements in motor function. However, anti-IFNAR treatment did not improve long-term functional recovery or decrease TBI neuropathology at 28 d post-injury. In summary, TBI induces a robust neuroinflammatory response that is associated with increased expression of IFN-β and other IFN-related genes. Inhibition of IFN-β reduces post-traumatic neuroinflammation and neurodegeneration, resulting in improved neurological recovery. Thus, IFN-β may be a potential therapeutic target for TBI.SIGNIFICANCE STATEMENT TBI frequently causes long-term neurological and psychiatric changes in head injury patients. TBI-induced secondary injury processes including persistent neuroinflammation evolve over time and can contribute to chronic neurological impairments. The present study demonstrates that TBI is followed by robust activation of type I IFN pathways, which have been implicated in microglial-associated neuroinflammation and chronic neurodegeneration. We examined the effects of genetic or pharmacological inhibition of IFN-β, a key component of type I IFN mechanisms to address its role in TBI pathophysiology. Inhibition of IFN-β signaling resulted in reduced neuroinflammation, attenuated neurobehavioral deficits, and limited tissue loss long after TBI. These preclinical findings suggest that IFN-β may be a potential therapeutic target for TBI.

The Therapeutic Potential of Conditioned Medium from Human Breast Milk Stem Cells in Treating Spinal Cord Injury

Study Design

Experimental animal study.

Purpose

This study investigated the therapeutic effects of human breast milk stem cell (BMSC)-conditioned medium (BMSC-CM) in a model of spinal cord injury (SCI) in male Sprague-Dawley rats.

Overview of Literature

SCI is one of the leading causes of disability in addition to sensory and motor impairment. So far, there have been no successful treatments for SCI. Given the positive outcomes associated with using stem cells and their derivatives as a treatment for various diseases, there is a growing interest in using them as an SCI treatment. Recent research has demonstrated that CM from stem cells has therapeutic advantages.

Methods

Human BMSCs were isolated and characterized, and CM was subsequently collected. Animals received an intrathecal administration of BMSC-CM after SCI. The activity of caspase-3 was measured to assess apoptosis, and levels of tumor necrosis factor-α and interleukin-1β were measured to assess inflammation. Also, sensory and locomotor performances were assessed after SCI and BMSC-CM administration.

Results

Administration of CM from BMSC reduced apoptosis and inflammation at the site of injury in a rat model of SCI (p<0.05). Motor, sensory, locomotor, and sensorimotor performances were significantly improved in rats that received BMSC-CM after SCI.

Conclusions

Intrathecal administration of BMSC-CM improved recovery in a rat model of SCI.

Neuron-Derived Plasma Exosome Proteins after Remote Traumatic Brain Injury

To identify long-term effects of traumatic brain injury (TBI) on levels of plasma neuron-derived exosome (NDE) protein biomarkers of cognitive impairment (CI), plasmas were obtained from four groups of older veterans, who were matched for age and sex: no TBI or CI (n = 42), no TBI with CI (n = 19), TBI without CI (n = 21), and TBI with CI (n = 26). The TBI was sustained 12 to 74 years before the study in 75%. The NDEs were enriched by sequential precipitation and anti-L1CAM antibody immunoabsorption, and extracted protein biomarkers were quantified by enzyme-linked immunosorbent assays. Chronic NDE biomarkers known to increase for three to 12 months after TBI, including cellular prion protein (PrPc), synaptogyrin-3, P-T181-tau, P-S396-tau, Aβ42, and interleukin (IL)-6, were elevated significantly in subjects who had TBI and CI compared with controls with TBI but no CI. Chronic NDE biomarker levels in subjects without TBI showed significantly higher levels of PrPc, synaptogyrin-3, P-T181-tau, and Aβ42, but not P-S396-tau and IL-6, in those with CI compared with controls without CI. The acute NDE biomarkers claudin-5, annexin VII, and aquaporin-4 were not increased in either group with CI. The NDE biomarkers P-S396-tau and IL-6, which are increased distinctively with CI after TBI, may prove useful in evaluating CI in older patients. Aβ42 and P-tau species, as well as their respective putative receptors, PrPc and synaptogyrin-3, remain elevated for decades after TBI and may mediate TBI-associated CI and be useful targets for development of drugs.

Immunomodulatory effects of Calcitriol in acute spinal cord injury in rats

Pharmacological therapy options for spinal cord injury (SCI) in acute phase have so far been limited, thus we focused on Calcitriol, FDA-approved biologically active form of vitamin D whose neuroprotective effects are increasingly recognized, to ameliorating damage following acute SCI in rats. Calcitriol (1 μg/kg) treatment for 7 consecutive days after SCI was compared SCI control and Sham control rat groups. Calcitriol-treated group had significantly improved outcome in standard functional recovery evaluation test (BBB) 12 weeks after SCI compared to SCI control, which was confirmed by increased ventral horn motor neurons in Calcitriol-treated group. In addition, proliferation test performed on lymphocytes from spleen and lymph nodes one week after SCI showed that calcitriol injection has a significant regulatory effect on Division Index (DI) in response to MBP stimulation compared to control SCI groups, which was associated with significant reduction in IFN-γ and IL-17A secretion and leukocyte infiltration into injury site. Along with confirmation of immunoregulatory aspects of Calcitriol treatment against myelin antigens in SCI, this study has shown that reducing the extent of progressive tissue loss by Calcitriol therapy in acute phase, could result in better recovery after SCI.

Neuron-Derived Exosome Proteins May Contribute to Progression From Repetitive Mild Traumatic Brain Injuries to Chronic Traumatic Encephalopathy

The recent recognition that Alzheimer disease-like pathology may be found in chronic traumatic encephalopathy (CTE) even after acute mild traumatic brain injury (mTBI) has increased the urgency of elucidating mechanisms, identifying biomarkers predictive of high risk of development of CTE, and establishing biomarker profiles indicative of impactful effects of treatments. Of the many proteins that are loaded into neuron-derived exosomes (NDEs) from damaged neurons after acute TBI, the levels of prion cellular protein (PRPc), coagulation factor XIII (XIIIa), synaptogyrin-3, IL-6, and aquaporins remain elevated for months. Prolonged heightened expression of aquaporins and IL-6 may account for the persistent central nervous system edema and inflammation of CTE. PRPc, XIIIa and synaptogyrin-3 bind and concentrate neurotoxic forms of oligomeric amyloid β peptides or P-tau for delivery into neurons at or distant from the site of trauma. Our progression factor hypothesis of CTE asserts that physiological neuronal proteins, such as PRPc, XIIIa, synaptogyrin-3, IL-6 and aquaporins, that increase in concentration in neurons and NDEs for months after acute TBI, are etiological contributors to CTE by either direct actions or by recruiting neurotoxic forms of Aβ peptides or P-tau. Such progression factors also may be useful new targets for development of drugs to prevent CTE.

Implications of immunotherapy with high-dose glatiramer acetate in acute phase of spinal cord injury in rats

Objective: Recently, many researches with different viewpoints have focused on application of immunotherapy agents in treatment of spinal cord injury (SCI) according to neuroprotective results in some neurodegenerative disease. Glatiramer acetate (GA) is the most commonly used drug for Multiple sclerosis (MS) patients that exerts an immunomodulatory effect against Myelin basic protein (MBP) antigen. Materials and methods: High-dose (2mg/kg) treatment of GA for 28 consecutive days after SCI was compared with its low-dose (0.5 mg/kg) treatment, SCI control and Sham control rat groups. Results: High-dose GA group had significantly worsened outcome in standard functional recovery evaluation test (BBB) 12 weeks after SCI compared to SCI control and low-dose GA groups, which was confirmed by augmented spinal cavity volume and reduced ventral horn motor neurons in high-dose GA group; however, there was no significant difference between low-dose GA and control SCI group. In addition, proliferation test performed on lymphocytes from spleen and lymph nodes one week after SCI showed that high-dose GA injection has more significant effect on Division Index (DI) in response to MBP stimulation compared to low-dose GA and control SCI groups, which was associated with significant increase in IFN-γ, IL-4, and IL-17A secretion. Conclusion: Along with confirmation of deleterious aspects of autoimmunity resulting from autoreactive lymphocytes against myelin antigens in SCI, this study has shown that high-dose immunotherapy using GA, especially in acute phase after SCI, overwhelms any neuroprotective effect of adoptive immune system.

Acidic Fibroblast Growth Factor in Spinal Cord Injury

Spinal cord injury (SCI), with an incidence rate of 246 per million person-years among adults in Taiwan, remains a devastating disease in the modern day. Elderly men with lower socioeconomic status have an even higher risk for SCI. Despite advances made in medicine and technology to date, there are few effective treatments for SCI due to limitations in the regenerative capacity of the adult central nervous system. Experiments and clinical trials have explored neuro-regeneration in human SCI, encompassing cell- and molecule-based therapies. Furthermore, strategies have aimed at restoring connections, including autologous peripheral nerve grafts and biomaterial scaffolds that theoretically promote axonal growth. Most molecule-based therapies target the modulation of inhibitory molecules to promote axonal growth, degrade glial scarring obstacles, and stimulate intrinsic regenerative capacity. Among them, acidic fibroblast growth factor (aFGF) has been investigated for nerve repair; it is mitogenic and pluripotent in nature and could enhance axonal growth and mitigate glial scarring. For more than 2 decades, the authors have conducted multiple trials, including human and animal experiments, using aFGF to repair nerve injuries, including central and peripheral nerves. In these trials, aFGF has shown promise for neural regeneration, and in the future, more trials and applications should investigate aFGF as a neurotrophic factor. Focusing on aFGF, the current review aimed to summarize the historical evolution of the utilization of aFGF in SCI and nerve injuries, to present applications and trials, to summarize briefly its possible mechanisms, and to provide future perspectives.

Altered levels of plasma neuron-derived exosomes and their cargo proteins characterize acute and chronic mild traumatic brain injury

Neuron-derived exosomes (NDEs) were enriched by anti-L1CAM antibody immunoabsorption from plasmas of subjects ages 18-26 yr within 1 wk after a sports-related mild traumatic brain injury (acute mTBI) ( n = 18), 3 mo or longer after the last of 2-4 mTBIs (chronic mTBI) ( n = 14) and with no recent history of TBI (controls) ( n = 21). Plasma concentrations of NDEs, assessed by counts and levels of extracted exosome marker CD81, were significantly depressed by a mean of 45% in acute mTBI ( P < 0.0001), but not chronic mTBI, compared with controls. Mean CD81-normalized NDE levels of a range of functional brain proteins were significantly abnormal relative to those of controls in acute but not chronic mTBI, including ras-related small GTPase 10, 73% decrease; annexin VII, 8.8-fold increase; ubiquitin C-terminal hydrolase L1, 2.5-fold increase; AII spectrin fragments, 1.9-fold increase; claudin-5, 2.7-fold increase; sodium-potassium-chloride cotransporter-1, 2.8-fold increase; aquaporin 4, 8.9-fold increase (3.6-fold increase in chronic mTBI); and synaptogyrin-3, 3.1-fold increase (1.3-fold increase in chronic mTBI) (all acute mTBI proteins P < 0.0001). In chronic mTBI, there were elevated CD81-normalized NDE levels of usually pathologic β-amyloid peptide 1-42 (1.6-fold, P < 0.0001), P-T181-tau (2.2-fold, P < 0.0001), P-S396-tau (1.6-fold, P < 0.01), IL-6 (16-fold, P < 0.0001), and prion cellular protein (PRPc) (5.1-fold, P < 0.0001) with lesser or greater (IL-6, PRPc) increases in acute mTBI. Increases in NDE levels of most neurofunctional proteins in acute, but not chronic, mTBI, and elevations of most NDE neuropathological proteins in chronic and acute mTBI delineated phase-specificity. Longitudinal studies of more mTBI subjects may identify biomarkers predictive of and etiologically involved in mTBI-induced neurodegeneration.-Goetzl, E. J., Elahi, F. M., Mustapic, M., Kapogiannis, D., Pryhoda, M., Gilmore, A., Gorgens, K. A., Davidson, B., Granholm, A.-C., Ledreux, A. Altered levels of plasma neuron-derived exosomes and their cargo proteins characterize acute and chronic mild traumatic brain injury.

Subcutaneous Maturation of Neural Stem Cell-Loaded Hydrogels Forms Region-Specific Neuroepithelium

A combinatorial approach integrating stem cells and capable of exploiting available cues is likely needed to regenerate lost neural tissues and ultimately restore neurologic functions. This study investigates the effects of the subcutaneous maturation of adult-derived neural stem cell (aNSCs) seeded into biomaterial constructs on aNSC differentiation and ultimate regional neuronal identity as a first step toward a future spinal cord injury treatment. To achieve this, we encapsulated rat aNSCs in chitosan-based hydrogels functionalized with immobilized azide-tagged interferon-γ inside a chitosan conduit. Then, we implanted these constructs in the subcutaneous tissues in the backs of rats in the cervical, thoracic, and lumbar regions for 4, 6, and 8 weeks. After harvesting the scaffolds, we analyzed cell differentiation qualitatively using immunohistochemical analysis and quantitatively using RT-qPCR. Results revealed that the hydrogels supported aNSC survival and differentiation up to 4 weeks in the subcutaneous environment as marked by the expression of several neurogenesis markers. Most interesting, the aNSCs expressed region-specific Hox genes corresponding to their region of implantation. This study lays the groundwork for further translational work to recapitulate the potentially undiscovered patterning cues in the subcutaneous tissue and provide support for the conceptual premise that our bioengineering approach can form caudalized region-specific neuroepithelium.

Cytokines in aortic dissection

Aortic dissection (AD) is one of the most dangerous forms of vascular disease, characterized by endometrial rupture and intramural hematoma formation. Generally, the pathological process is complicated and closely related to the infiltration of inflammatory cells into the aortic wall and apoptosis of vascular smooth muscle cells. Currently, multiple cytokines, including interleukins, interferon, the tumor necrosis factor superfamily, colony stimulating factor, chemotactic factor, growth factor and so on, have all been demonstrated to play a critical role in AD. Additionally, studies of the link between cytokines and AD could deepen our understanding of the disease and may guide future treatment therapies; therefore, this review focuses on the role of cytokines in AD.