Interleukin-17 in post-stroke neurodegeneration

Peripheral, but not central, IGF-1 treatment attenuates stroke-induced cognitive impairment in middle-aged female Sprague Dawley rats: The gut as a therapeutic target

Stroke results in immediate sensory or motor disability and increases the risk for long term cognitive-affective impairments. Thus, therapies are urgently needed to improve quality of life for stroke survivors, especially women who are at a greater risk for severe stroke after menopause. Most current research on stroke therapies target the central nervous system; however, stroke also impacts peripheral organ systems. Our studies using acyclic (estrogen-deficient) middle aged female Sprague Dawley rats show that this group not only displays worse outcomes after stroke as compared to adult females, but also has lower levels of the neuroprotective peptide Insulin-like Growth Factor (IGF1) in circulation. Intracerebroventricular (ICV) administration of IGF1 to this group decreases infarct volume and improves sensory motor performance in the acute phase. In this study, we show that, despite this neuroprotection, ICV-IGF1 did not reduce peripheral inflammation or improve post stroke cognitive impairment in the chronic phase. In view of the evidence that stroke induces rapid gut dysfunction, we tested whether systemic delivery of IGF1 (intraperitoneal, IP) would promote gut health and consequently improve long-term behavioral outcomes. Surprisingly, while IP-IGF1, delivered 4 h and 24 h after ischemic stroke, did not reduce infarct volume or acute sensory motor impairment, it significantly attenuated circulating levels of pro-inflammatory cytokines, and attenuated stroke-induced cognitive impairment. In addition, IP-IGF1 treatment reduced gut dysmorphology and gut dysbiosis. Our data support the conclusion that therapeutics targeting peripheral targets are critical for long-term stroke recovery, and that gut repair is a novel therapeutic target to improve brain health in aging females.

Gut Microbiome variation in patients with early-stage mild-to-moderate intracerebral hemorrhage: A pilot study exploring therapeutic targets

BACKGROUND

The significant morbidity and mortality rates of acute intracerebral hemorrhage (ICH) are well-known around the world. The link between gut microbiota and different types of strokes is becoming more studied. The goal of this study was to look at the relationships between intestinal flora and early-stage mild-to-moderate ICH (emICH), and to provide a new perspective for adjunctive treatment of emICH.

METHODS

Fecal samples from 100 participants with emICH (n=50) and healthy individuals (n=50) in this study were collected as well as analyzed utilizing 16S rRNA gene amplicon sequencing in order to characterize the gut microbial community.

RESULTS

Distinct microbial communities are present within each group, with emICH patients exhibiting a diminished diversity and uniformity in their microbial profiles. A notable shift in the gut microbiota composition of emICH patients has been observed, characterized by an upsurge in pro-inflammatory microbes belonging to the Euryarchaeota phylum and a concurrent decline in beneficial Bacteroidetes species. Concurrently, significant associations and patterns among operational taxonomic units (OTUs) were identified in emICH patients. A panel of biomarkers (WAL_1855D, Methanobrevibacter, Streptococcus, Bacteroides, Coprococcus, Lachnospira) has been effectively utilized to distinguish emICH patients from healthy individuals, with an area under the curve (AUC) of 0.845. Additionally, an analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation uncovered several perturbed pathways in emICH patients, predominantly those related to metabolic processes and the inflammatory response. Moreover, predictive profiling of the microbiome's phenotypic traits suggests that emICH patients are likely to harbor a higher prevalence of Gram-negative bacteria and potential opportunistic pathogens compared to healthy controls.

CONCLUSIONS

The gut microbiota ecosystem of emICH patients is disrupted, characterized primarily by an increase in pro-inflammatory microbiota, elevated inflammatory signaling pathways, and metabolic dysregulation. Furthermore, microbiota modulation may be seen as a novel approach for the adjunctive treatment of emICH.

Biochemical, biomechanical and imaging biomarkers of ischemic stroke: Time for integrative thinking

Stroke is one of the leading causes of adult disability affecting millions of people worldwide. Post-stroke cognitive and motor impairments diminish quality of life and functional independence. There is an increased risk of having a second stroke and developing secondary conditions with long-term social and economic impacts. With increasing number of stroke incidents, shortage of medical professionals and limited budgets, health services are struggling to provide a care that can break the vicious cycle of stroke. Effective post-stroke recovery hinges on holistic, integrative and personalized care starting from improved diagnosis and treatment in clinics to continuous rehabilitation and support in the community. To improve stroke care pathways, there have been growing efforts in discovering biomarkers that can provide valuable insights into the neural, physiological and biomechanical consequences of stroke and how patients respond to new interventions. In this review paper, we aim to summarize recent biomarker discovery research focusing on three modalities (brain imaging, blood sampling and gait assessments), look at some established and forthcoming biomarkers, and discuss their usefulness and complementarity within the context of comprehensive stroke care. We also emphasize the importance of biomarker guided personalized interventions to enhance stroke treatment and post-stroke recovery.

Concordant and Discordant Cerebrospinal Fluid and Plasma Cytokine and Chemokine Responses in Mild Cognitive Impairment and Early-Stage Alzheimer's Disease

Neuroinflammation may be a pathogenic mediator and biomarker of neurodegeneration at the boundary between mild cognitive impairment (MCI) and early-stage Alzheimer's disease (AD). Whether neuroinflammatory processes are endogenous to the central nervous system (CNS) or originate from systemic (peripheral blood) sources could impact strategies for therapeutic intervention. To address this issue, we measured cytokine and chemokine immunoreactivities in simultaneously obtained lumbar puncture cerebrospinal fluid (CSF) and serum samples from 39 patients including 18 with MCI or early AD and 21 normal controls using a 27-plex XMAP bead-based enzyme-linked immunosorbent assay (ELISA). The MCI/AD combined group had significant (p < 0.05 or better) or statistically trend-wise (0.05 ≤ p ≤ 0.10) concordant increases in CSF and serum IL-4, IL-5, IL-9, IL-13, and TNF-α and reductions in GM-CSF, b-FGF, IL-6, IP-10, and MCP-1; CSF-only increases in IFN-y and IL-7 and reductions in VEGF and IL-12p70; serum-only increases in IL-1β, MIP-1α, and eotaxin and reductions in G-CSF, IL-2, IL-8 and IL-15; and discordant CSF-serum responses with reduced CSF and increased serum PDGF-bb, IL-17a, and RANTES. The results demonstrate simultaneously parallel mixed but modestly greater pro-inflammatory compared to anti-inflammatory or neuroprotective responses in CSF and serum. In addition, the findings show evidence that several cytokines and chemokines are selectively altered in MCI/AD CSF, likely corresponding to distinct neuroinflammatory responses unrelated to systemic pathologies. The aggregate results suggest that early management of MCI/AD neuroinflammation should include both anti-inflammatory and pro-neuroprotective strategies to help prevent disease progression.

Exploratory Transcriptomic Profiling Reveals the Role of Gut Microbiota in Vascular Dementia

Stroke is the second most common cause of cognitive impairment and dementia. Vascular dementia (VaD), a cognitive impairment following a stroke, is common and significantly impacts the quality of life. We recently demonstrated via gut microbe transplant studies that the gut microbe-dependent trimethylamine-N-oxide (TMAO) pathway impacts stroke severity, both infarct size and long-term cognitive outcomes. However, the molecular mechanisms that underly the role of the microbiome in VaD have not been explored in depth. To address this issue, we performed a comprehensive RNA-sequencing analysis to identify differentially expressed (DE) genes in the ischemic cerebral cortex of mouse brains at pre-stroke and post-stroke day 1 and day 3. A total of 4016, 3752 and 7861 DE genes were identified at pre-stroke and post-stroke day 1 and day 3, respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated pathways of neurodegeneration in multiple diseases, chemokine signaling, calcium signaling, and IL-17 signaling as the key enriched pathways. Inflammatory response genes interleukin-1 beta (Il-1β), chemokines (C-X-C motif chemokine ligand 10 (Cxcl10), chemokine ligand 2 (Ccl2)), and immune system genes (S100 calcium binding protein 8 (S100a8), lipocalin-2 (Lcn2)) were among the most significantly upregulated genes. Hypocretin neuropeptide precursor (Hcrt), a neuropeptide, and transcription factors such as neuronal PAS domain protein 4 (Npas4), GATA binding protein 3 (Gata3), and paired box 7 (Pax7) were among the most significantly downregulated genes. In conclusion, our results indicate that higher plasma TMAO levels induce differential mRNA expression profiles in the ischemic brain tissue in our pre-clinical stroke model, and the predicted pathways provide the molecular basis for regulating the TMAO-enhanced neuroinflammatory response in the brain.

Association between Systemic Immune Inflammation Index and Cognitive Impairment after Acute Ischemic Stroke

Background and Aims: Post-stroke cognitive impairment (PSCI) is one of the major complications after ischemic stroke. PSCI has been shown to be associated with low-grade systemic inflammation. As a novel inflammatory marker, the systemic immune-inflammation (SII) index could reflect clinical outcomes in severe cardiovascular diseases. We therefore performed a prospective study to investigate the correlation between the SII index and the risk of PSCI in patients with ischemic stroke. Methods: We prospectively enrolled 254 patients with ischemic stroke with symptoms onset <72 h. The SII index was detected within 24 h after admission. The Montreal Cognitive Scale (MoCA) was utilized to evaluate cognitive function, and PSCI was defined as a MoCA score of <25 points. Results: During the 3-month follow-up, 70 participants (27.6%) had mild cognitive impairment and 60 (23.6%) had severe cognitive impairment. In binary logistic regression analysis, each one-standard deviation increase in the SII index was significantly associated with the prevalence of PSCI after adjusting for age, sex, and other confounders (odds ratio 2.341; 95% confidence interval, 1.439–3.809, p = 0.001). Similar significant findings were observed when SII was defined as a categorical variable. In addition, the multiple-adjusted spline regression model showed a linear association between the SII index and cognitive impairment (p = 0.003 for linearity). Conclusions: Our study indicated that an increased SII index was closely related to PSCI at 3 months in patients with ischemic stroke. Further research is required to evaluate the efficacy of inflammation management in these patients.

DL-3-n-butylphthalide (NBP) alleviates poststroke cognitive impairment (PSCI) by suppressing neuroinflammation and oxidative stress

Currently, the recovery of cognitive function has become an essential part of stroke rehabilitation. DL-3-n-butylphthalide (NBP) is a neuroprotective reagent and has been used in stroke treatment. Clinical studies have confirmed that NBP can achieve better cognitive outcomes in ischemic stroke patients than in healthy controls. In this study, we aimed to investigate the influences of NBP on cognitive function in an ischemic reperfusion (I/R) rat model. Our results showed that NBP profoundly decreased neurological scores, reduced cerebral infarct areas and enhanced cerebral blood flow (CBF). NBP potently alleviated poststroke cognitive impairment (PSCI) including depression-like behavior and learning, memory and social cognition impairments, in I/R rats. NBP distinctly suppressed the activation of microglia and astrocytes and improved neuron viability in the ischemic brain. NBP inhibited the expression of inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), by targeting the nuclear factor kappa B/inducible nitric oxide synthase (NF-κB/iNOS) pathway and decreased cerebral oxidative stress factors, including reactive oxygen species (ROS) and malondialdehyde (MDA), by targeting the kelch like ECH associated protein 1/nuclear factor-erythroid 2 p45-related factor 2 (Keap1/Nrf2) pathway in the ischemic brain. The current study revealed that NBP treatment improved neurological function and ameliorated cognitive impairment in I/R rats, possibly by synergistically suppressing inflammation and oxidative stress.

Neutrophil Extracellular Traps in Cerebral Ischemia/Reperfusion Injury: Friend and Foe

Cerebral ischemic injury, one of the leading causes of morbidity and mortality worldwide, triggers various central nervous system (CNS) diseases, including acute ischemic stroke (AIS) and chronic ischemia-induced Alzheimer's disease (AD). Currently, targeted therapies are urgently needed to address neurological disorders caused by cerebral ischemia/reperfusion injury (CI/RI), and the emergence of neutrophil extracellular traps (NETs) may be able to relieve the pressure. Neutrophils are precursors to brain injury following ischemic stroke and exert complicated functions. NETs extracellularly release reticular complexes of neutrophils, i.e., double-stranded DNA (dsDNA), histones, and granulins. Paradoxically, NETs play a dual role, friend and foe, under different conditions, for example, physiological circumstances, infection, neurodegeneration, and ischemia/reperfusion. Increasing evidence indicates that NETs exert anti-inflammatory effects by degrading cytokines and chemokines through protease at a relatively stable and moderate level under physiological conditions, while excessive amounts of NETs release (NETosis) irritated by CI/RI exacerbate the inflammatory response and aggravate thrombosis, disrupt the blood-brain barrier (BBB), and initiates sequential neuron injury and tissue damage. This review provides a comprehensive overview of the machinery of NETs formation and the role of an abnormal cascade of NETs in CI/RI, as well as other ischemia-induced neurological diseases. Herein, we highlight the potential of NETs as a therapeutic target against ischemic stroke that may inspire translational research and innovative clinical approaches.

An integrated cytokine and kynurenine network as the basis of neuroimmune communication

Two of the molecular families closely associated with mediating communication between the brain and immune system are cytokines and the kynurenine metabolites of tryptophan. Both groups regulate neuron and glial activity in the central nervous system (CNS) and leukocyte function in the immune system, although neither group alone completely explains neuroimmune function, disease occurrence or severity. This essay suggests that the two families perform complementary functions generating an integrated network. The kynurenine pathway determines overall neuronal excitability and plasticity by modulating glutamate receptors and GPR35 activity across the CNS, and regulates general features of immune cell status, surveillance and tolerance which often involves the Aryl Hydrocarbon Receptor (AHR). Equally, cytokines and chemokines define and regulate specific populations of neurons, glia or immune system leukocytes, generating more specific responses within restricted CNS regions or leukocyte populations. In addition, as there is a much larger variety of these compounds, their homing properties enable the superimposition of dynamic variations of cell activity upon local, spatially limited, cell populations. This would in principle allow the targeting of potential treatments to restricted regions of the CNS. The proposed synergistic interface of 'tonic' kynurenine pathway affecting baseline activity and the superimposed 'phasic' cytokine system would constitute an integrated network explaining some features of neuroimmune communication. The concept would broaden the scope for the development of new treatments for disorders involving both the CNS and immune systems, with safer and more effective agents targeted to specific CNS regions.

Roles of peripheral immune cells in the recovery of neurological function after ischemic stroke

Stroke is a leading cause of mortality and long-term disability worldwide, with limited spontaneous repair processes occurring after injury. Immune cells are involved in multiple aspects of ischemic stroke, from early damage processes to late recovery-related events. Compared with the substantial advances that have been made in elucidating how immune cells modulate acute ischemic injury, the understanding of the impact of the immune system on functional recovery is limited. In this review, we summarized the mechanisms of brain repair after ischemic stroke from both the neuronal and non-neuronal perspectives, and we review advances in understanding of the effects on functional recovery after ischemic stroke mediated by infiltrated peripheral innate and adaptive immune cells, immune cell-released cytokines and cell-cell interactions. We also highlight studies that advance our understanding of the mechanisms underlying functional recovery mediated by peripheral immune cells after ischemia. Insights into these processes will shed light on the double-edged role of infiltrated peripheral immune cells in functional recovery after ischemic stroke and provide clues for new therapies for improving neurological function.

Cohort study on the differential expression of inflammatory and angiogenic factors in thrombi, cerebral and peripheral plasma following acute large vessel occlusion stroke

Inflammation plays an important role in the pathogenesis of stroke. The differential expression of inflammatory and angiogenic factors in thrombi and plasma remain undefined. In this observational cohort study, we evaluated angiogenic factors and inflammatory cytokines, in cerebral thrombi, local cerebral plasma (CP), and peripheral plasma (PP) in patients with acute ischemic stroke. Protein analysis of thrombi, CP and PP were used to measure angiogenic and inflammatory proteins using electrochemiluminescence. Our data indicate that VEGF-A, VEGF-C, bFGF, IL-4, IL-13, IL-1β, IL-2, IL-8, IL-16, IL-6 and IL-12p70 were higher in the thrombi of acute ischemic stroke patients than in the CP and PP of stroke patients. Moreover, the protein levels of GM-CSF were lower in the PP than in the CP and the clot. Moreover, VEGF-D, Flt-1, PIGF, TIE-2, IL-5, TNF-β, IL-15, IL-12/IL-23p40, IFN-γ and IL-17A were higher in PP and CP than in thrombi. Our results show that cytokines mediating the inflammatory response and proteins involved in angiogenesis are differentially expressed in thrombi within the cerebral and peripheral circulations. These data highlight the importance of identifying new biomarkers in different compartments of the circulatory system and in thrombi that may be used for the diagnosis and treatment of stroke patients.

The mechanism of action of the combination of Astragalus membranaceus and Ligusticum chuanxiong in the treatment of ischemic stroke based on network pharmacology and molecular docking

Since 1990, the incidence of stroke has been rising to become the second leading cause of death in the world, posing a huge burden and challenge to society and families. Astragalus membranaceus and Ligusticum chuanxiong (A&L) have been used as traditional Chinese medicine (TCM) prescriptions to treat and prevent the occurrence of ischemic stroke (IS), but their mechanism of action on the disease has not been fully elucidated. The main objective of this study was to reveal the pharmacological mechanism of A&L in the treatment of IS and to perform preliminary validation. The active ingredients of A&L were obtained from the systematic pharmacology platform of traditional Chinese medicine (TCMSP) database, whereas the genes of IS were obtained from 2 major databases, DrugBank and GeneCards. Cytoscape_v3.8.2 was used to construct the TCM-active ingredient and TCM-active ingredient-cross-target-disease relationship maps, and the MCODE plug-in was used to obtain the core genes, whereas the protein-protein interaction maps were obtained from the STRING database. The results of gene ontology and Kyoto encyclopedia of genes and genomes enrichment were obtained using the Hiplot online tool, and the small molecules in the relevant signalling pathways were verified by molecular docking using AutoDock. A&L contained a total of 26 eligible active ingredients, sharing 161 common targets with IS. A total of 58 core genes with 1326 edges were obtained using the MCODE plug-in. Gene ontology and Kyoto encyclopedia of genes and genomes enrichment results showed association with interleukin-17 signaling pathway, lipid and atherosclerosis, tumor necrosis factor signaling pathway, and Toll-like receptor signaling pathway, which mainly mediates the development of inflammatory responses. Furthermore, molecular docking was conducted and most of the components were found to have good binding to the receptors. This study demonstrates that A&L can be used to treat IS by controlling the inflammatory response through multiple targets and multiple pathways, and provides a reference for subsequent trials.

Change of Serum Biomarkers to Post-Thrombolytic Symptomatic Intracranial Hemorrhage in Stroke

Background

Symptomatic intracranial hemorrhage (sICH) is a terrible complication after intravenous alteplase in stroke, and numerous biomarkers have been investigated. However, the change of biomarkers to sICH has not been well determined.

Aim

To investigate the association between the change of biomarkers and sICH.

Methods

This is a prospective cohort study, and patients with sICH within 24 h after thrombolysis were enrolled, while patients without sICH were matched by propensity score matching with a ratio of 1:1. The blood samples were collected before and 24 h after intravenous thrombolysis (IVT), and preset 49 serum biomarkers were measured by microarray analysis. Protein function enrichment analyses were performed to detect the association between the change of biomarkers and sICH.

Results

Of consecutive 358 patients, 7 patients with sICH in 24 h were assigned to the sICH group, while 7 matched patients without any ICH were assigned to the non-sICH group. A total of 9 biomarkers were found to significantly change before vs. after thrombolysis between groups, including increased biomarkers, such as brain-derived neurotrophic factor, C-C motif chemokine ligand (CCL)-24, interleukin (IL)-6, IL-10, IL-18, and vascular endothelial growth factor, and decreased biomarkers, such as CCL-11, intercellular adhesion molecule-1, and IL-7.

Conclusions

This is the first study to identify changes in serum biomarkers in patients with sICH after IVT, and found that 6 neuroinflammatory and 3 neuroprotective biomarkers may be associated with brain injury following post-thrombolytic sICH.

Clinical Trial Registration

https://www.clinicaltrials.gov, identifier: NCT02854592.

Functional Assessment of Stroke-Induced Regulation of miR-20a-3p and Its Role as a Neuroprotectant

MicroRNAs have gained popularity as a potential treatment for many diseases, including stroke. This study identifies and characterizes a specific member of the miR-17-92 cluster, miR-20a-3p, as a possible stroke therapeutic. A comprehensive microRNA screening showed that miR-20a-3p was significantly upregulated in astrocytes of adult female rats, which typically have better stroke outcomes, while it was profoundly downregulated in astrocytes of middle-aged females and adult and middle-aged males, groups that typically have more severe stroke outcomes. Assays using primary human astrocytes and neurons show that miR-20a-3p treatment alters mitochondrial dynamics in both cell types. To assess whether stroke outcomes could be improved by elevating astrocytic miR-20a-3p, we created a tetracycline (Tet)-induced recombinant adeno-associated virus (rAAV) construct where miR-20a-3p was located downstream a glial fibrillary acidic protein promoter. Treatment with doxycycline induced miR-20-3p expression in astrocytes, reducing mortality and modestly improving sensory motor behavior. A second Tet-induced rAAV construct was created in which miR-20a-3p was located downstream of a neuron-specific enolase (NSE) promoter. These experiments demonstrate that neuronal expression of miR-20a-3p is vastly more neuroprotective than astrocytic expression, with animals receiving the miR-20a-3p vector showing reduced infarction and sensory motor improvement. Intravenous injections, which are a therapeutically tractable treatment route, with miR-20a-3p mimic 4 h after middle cerebral artery occlusion (MCAo) significantly improved stroke outcomes including infarct volume and sensory motor performance. Improvement was not observed when miR-20a-3p was given immediately or 24 h after MCAo, identifying a unique delayed therapeutic window. Overall, this study identifies a novel neuroprotective microRNA and characterizes several key pathways by which it can improve stroke outcomes.

Uncovering the Mechanism of Chuanhong Stroke Capsule in the Treatment of Stroke Based on Network Pharmacology and Molecular Docking Technology

Background and Objective: Chuanhong Stroke Capsule (CHSC) has good clinical efficacy in the treatment of cerebral ischemic stroke (CIS) patients. This study aimed to investigate the pharmacological mechanisms of CHSC in treating CIS using bioinformatics. Methods: The active compounds of CHSC were screened by searching Traditional Chinese Medicine System Pharmacological Database and Analysis Platform (TCMSP), Swiss absorption, distribution, metabolism, and excretion (ADME), PubMed, and China National Knowledge Infrastructure (CNKI) databases. Besides, the potential targets of active compounds were obtained through TCMSP and Swiss Target Prediction databases. CIS targets were obtained from GeneCards, Online Mendelian Inheritance in Man (OMIM), and Gene Expression Omnibus (GEO) databases. CHSC-CIS intersection targets were identified by matching the two, and prediction and analysis of biological functions and pathways of intersection targets was used the enrichments of gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, protein–protein interaction (PPI) network, herb-target, and compound-target network of CHSC-CIS were constructed by Cytoscape3.7.2, and herb-compound-pathway network was drawn with Sankey diagram. Finally, AutoDock was used for molecular docking verification, and identifying the active binding sites in target proteins. Results: A total of 293 putative targets were obtained from 62 active compounds in CHSC. Among them, 209 targets were related to CIS. PPI network showed that the top 16 key targets were RELA, JUN, FOS, MAPK1, AKT1, etc. KEGG pathway enrichment analysis demonstrated that CHSC was enriched in PI3K-Akt, MAPK, and TNF signaling pathways. In addition, GO enrichment analysis showed the significant enrichment of CHSC in the following categories: kinase binding, cellular response to nitrogen compound, etc. Network topology analysis showed that quercetin, luteolin, kaempferol, etc., were the key components in CHSC. Finally, molecular docking studies suggested that the active components in CHSC had a good binding ability with the key targets. Conclusions: Our study demonstrated that CHSC exerted the effect in treating CIS by the characteristics of multi-target and multi-pathway, thereby providing a theoretical basis for further study of the effective components and mechanism of CHSC in the treatment of CIS.

Benefits of a Skull-Interfaced Flexible and Implantable Multilight Emitting Diode Array for Photobiomodulation in Ischemic Stroke

Photobiomodulation (PBM) has received attention due to its potential for improving tissue function and enhancing regeneration in stroke. A lightweight, compact, and simple system of miniaturized electronic devices consisting of packaged light-emitting diodes (LEDs) that incorporates a flexible substrate for in vivo brain PBM in a mouse model is developed. Using this device platform, the preventive and therapeutic effects of PBM affixed to the exposed skull of mice in the photothrombosis and middle cerebral artery occlusion stroke model are evaluated. Among the wavelength range of 630, 850, and 940 nm LED array, the PBM with 630-nm LED array is proved to be the most effective for reducing the infarction volume and neurological impairment after ischemic stroke. Moreover, the PBM with 630 nm LED array remarkably improves the capability of spatial learning and memory in the chronic poststroke phase, attenuates AIM2 inflammasome activation and inflammasome-mediated pyroptosis, and modulates microglial polarization in the hippocampus and cortex 7 days following ischemic stroke. Thus, PBM may prevent tissue and functional damage in acute ischemic injury, thereby attenuating the development of cognitive impairment after stroke.

The association between plasma soluble triggering receptor expressed on myeloid cells 2 and cognitive impairment after acute ischemic stroke

BACKGROUND

Previous researches have suggested that soluble triggering receptor expressed on myeloid cells 2 (sTREM2) plays a pivotal role in central nervous system pathologies and the development of neurodegenerative disorders. This study aimed to prospectively investigate the association between plasma sTREM2 levels and post-stroke cognitive impairment (PSCI).

METHODS

A sample of 599 consecutive acute ischemic stroke patients with sTREM2 measurements from the China Antihypertensive Trial in Acute Ischemic Stroke were eventually included in this analysis. Cognitive impairment was defined as a score of <25 for Mini-Mental State Examination, measured at 3-month follow up. Binary logistic regression was used to estimate the odds ratios (ORs) of plasma sTREM2 levels on the risk of PSCI.

RESULTS

Of the 599 participants (mean age, 60.0 ± 10.4 years; male, 70.5%), 228 (38.1%) patients were diagnosed as PSCI. The risk of PSCI elevated significantly with higher plasma sTREM2 levels (p for trend <0.01). After adjusting for several confounding factors, the ORs for the highest quartile of sTREM2 compared with the lowest quartile was 2.06 (95% confidence interval, 1.20-3.53) for PSCI. Moreover, the addition of sTREM2 to the conventional model with established risk factors significantly improved risk discrimination (C-statistics increased from 0.668 to 0.691, p = 0.02) and reclassification (net reclassification improvement: 32.2%, p < 0.001; integrated discrimination improvement: 1.3%, p = 0.01) for PSCI.

LIMITATIONS

Results might be subject to selective bias and potential confounding.

CONCLUSIONS

The present study demonstrated that elevated level of plasma sTREM2 may be associated with PSCI, and sTREM2 has potential value in predicting PSCI.

Effect of exposure to low doses of ozone on interleukin 17A expression during progressive neurodegeneration in the rat hippocampus

INTRODUCTION

Chronic exposure to low doses of ozone causes oxidative stress and loss of regulation of the inflammatory response, leading to progressive neurodegeneration.

OBJECTIVE

We studied the effect of chronic exposure to low doses of ozone on IL-17A concentration and expression in neurons, microglia, astrocytes, and T cells in the rat hippocampus.

METHODS

We used 72 Wistar rats, divided into 6 groups (n=12): a control group (no ozone exposure) and 5 groups exposed to ozone (0.25ppm, 4h daily) for 7, 15, 30, 60, and 90 days. We processed 6 rats from each group to quantify IL-17A by ELISA; the remaining 6 were processed for immunohistochemistry (against IL-17A and GFAP, Iba1, NeuN, and CD3).

RESULTS

The ELISA study data showed a significant increase in IL-17A concentrations in the 7-, 15-, 30-, and 60-day exposure groups, with regard to the control group (P<.05). Furthermore, they indicate that hippocampal neurons were the cells showing greatest immunoreactivity against IL-17A between 60 and 90 days of exposure to ozone; we also observed an increase in activated astrocytes in the 30- and 60-day exposure groups.

CONCLUSION

Exposure to ozone in rats induces an increase in IL-17A expression, mainly in hippocampal neurons, accompanied by hippocampal astrocyte activation during chronic neurodegeneration, similar to that observed in Alzheimer disease in humans.

IL-23 and IL-17 in acute ischemic stroke: Correlation with stroke scales and prognostic value

BACKGROUND AND PURPOSE

Inflammation plays a crucial role in brain damage following stroke. Here, we evaluate interleukin 23 (IL-23) and interleukin 17 (IL-17) in the inflammatory process and its relations with neurological findings of patients with acute ischemic stroke (AIS).

MATERIAL AND METHODS

Fifty consecutive patients with AIS admitted to our hospital within 24 h of stroke onset were enrolled in a prospective cohort study. Serum IL-23 and IL-17 were measured in the first, third and fifth day after the stroke. Neurological stroke severity were determined with the National Institutes of Health Stroke Scale (NIHSS) and with the modified Rankin Scale (mRS) within 24 h of the acute event, on the third and fifth day after the stroke, and at the time of hospital discharge.

RESULTS

Both neurological scores for stroke outcome at hospital discharge were related to IL-23 protein within 24 h and on the fifth day, but with low stroke outcome predictive values. The other measurements did not show predictive capacity for stroke outcome. There was a significant increase in median serum concentrations of IL-23 on the fifth day (p < 0.001) and in IL-17 median levels on the third day compared to the first 24 h after the acute injury (p < 0.001). However, there was no correlation between IL-23 and IL-17 levels with neurological outcomes at hospital discharge or after four years.

CONCLUSION

IL-23 and IL-17 increase after stroke, but had no sufficient discriminative capacity to be of clinical use as outcome stroke predictors.

Association between Blood Pressure, Blood Pressure Variability, and Post-Stroke Cognitive Impairment

After stroke, dynamic changes take place from necrotic-apoptotic continuum, inflammatory response to poststroke neurogenesis, and remodeling of the network. These changes and baseline brain pathology such as small vessel disease (SVD) and amyloid burden may be associated with the occurrence of early or late poststroke cognitive impairment (PSCI) or dementia (PSD), which affect not only stroke victims but also their families and even society. We reviewed the current concepts and understanding of the pathophysiology for PSCI/PSD and identified useful tools for the diagnosis and the prediction of PSCI in serological, CSF, and image characteristics. Then, we untangled their relationships with blood pressure (BP) and blood pressure variability (BPV), important but often overlooked risk factors for PSCI/PSD. Finally, we provided evidence for the modifying effects of BP and BPV on PSCI as well as pharmacological and non-pharmacological interventions and life style modification for PSCI/PSD prevention and treatment.

Vγ4 T cell-derived IL-17A is essential for amplification of inflammatory cascades in ischemic brain tissue after stroke

BACKGROUND

Through amplifying inflammatory cascades, IL-17A produced by γδ T cells potently attracts neutrophils to the site of injury for exacerbating ischemic tissue damage. Our goal was to identify the precise role of γδ T cell subsets in ischemic brain tissue damage of stroke.

METHODS

In a model of experimental stroke, we analyzed the functions of Vγ1 and Vγ4 T cells on γδ T cell-mediated ischemic brain tissue damage of stroke.

RESULTS

We identified that, in stroke, Vγ4 T cells are essential for γδ T cell-mediated ischemic brain tissue damage through providing an early source of IL-17A. Both CCL20 and IL-1β/IL-23 are deeply involved in Vγ4 T cell-mediated amplification of inflammatory responses: CCL20 might promote Vγ4 T cells recruit to infract hemisphere, and IL-1β/IL-23 powerfully enhance IL-17A production mediated by the infiltrating Vγ4 T cells. Moreover, Vγ4 T cell-derived IL-17A enhances both CCL20 and IL-1β, and conversely, CCL20 and IL-1β further enhance both recruitment and IL-17A production of IL-17A-positive cells, in a classic positive feedback loop.

CONCLUSION

Our data suggest that in the setting of ischemic stroke, Vγ4 T cell-derived IL-17A, CCL20 and IL-1β/IL-23 in infract hemisphere coordinately to amplify inflammatory cascades and exacerbate ischemic tissue damage.

Investigation of the Multi-Target Mechanism of Guanxin-Shutong Capsule in Cerebrovascular Diseases: A Systems Pharmacology and Experimental Assessment

Guanxin-Shutong capsule (GXSTC), a combination of Mongolian medicines and traditional herbs, has been clinically proven to be effective in treating cerebrovascular diseases (CBVDs). However, the underlying pharmacological mechanisms of GXSTC in CBVDs remain largely unknown. In this study, a combination of systems pharmacology and experimental assessment approach was used to investigate the bioactive components, core targets, and possible mechanisms of GXSTC in the treatment of CBVDs. A total of 15 main components within GXSTC were identified using high-performance liquid chromatography coupled with diode array detector (HPLC-DAD) and a literature research. Fifty-five common genes were obtained by matching 252 potential genes of GXSTC with 462 CBVD-related genes. Seven core components in GXSTC and 12 core genes of GXSTC on CBVDs were further determined using the protein-protein interaction (PPI) and component-target-pathway (C-T-P) network analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis results predicted that the molecular mechanisms of GXSTC on CBVDs were mainly associated with the regulation of the vascular endothelial function, inflammatory response, and neuronal apoptosis. Molecular docking results suggested that almost all of core component-targets have an excellent binding activity (affinity < −5 kcal/mol). More importantly, in middle cerebral artery occlusion (MCAO) -injured rats, GXSTC significantly improved the neurological function, reduced the infarct volume, and decreased the percentage of impaired neurons in a dose-dependent manner. Western blotting results indicated that GXSTC markedly upregulated the expression of vascular endothelial growth factor A (VEGFA) and endothelial nitric oxide synthase (eNOS), while downregulating the expression of cyclooxygenase-2 (COX-2) and transcription factor AP-1 (c-Jun) in MCAO-injured rats. These findings confirmed our prediction that GXSTC exerts a multi-target synergetic mechanism in CBVDs by maintaining vascular endothelial function, inhibiting neuronal apoptosis and inflammatory processes. The results of this study may provide a theoretical basis for GXSTC research and the clinical application of GXSTC in CBVDs.

Intestinal Barrier Dysfunction Participates in the Pathophysiology of Ischemic Stroke

The gastrointestinal tract is a major organ for the body to absorb nutrients, water and electrolytes. At the same time, it is a tight barrier to resist the invasion of harmful substances and maintain the homeostasis of the internal environment. Destruction of the intestinal barrier is linked to the digestive system, cardiovascular system, endocrine system and other systemic diseases. Mounting evidence suggests that ischemic stroke not only changes the intestinal microbes, but also increases the permeability of the intestinal barrier, leading to bacterial translocation, infection, and even sepsis. The intestinal barrier, as part of the gut-brain axis, has also been proven to participate in the pathophysiological process of ischemic stroke. However, little attention has been paid to it. Since ischemic stroke is a major public health issue worldwide, there is an urgent need to know more about the disease for better prevention, treatment and prognosis. Therefore, understanding the pathophysiological relationship between ischemic stroke and the intestinal barrier will help researchers further uncover the pathophysiological mechanism of ischemic stroke and provide a novel therapeutic target for the treatment of ischemic stroke. Here, we review the physiology and pathology between ischemic stroke and intestinal barrier based on related articles published in the past ten years about the relationship between ischemic stroke, stroke risk factors and intestinal flora, intestinal barrier, and discuss the following parts: the intestinal barrier; possible mechanisms of intestinal barrier destruction in ischemic stroke; intestinal barrier destruction caused by stroke-related risk factors; intestinal barrier dysfunction in ischemic stroke; targeting the intestinal barrier to improve stroke; conclusions and perspectives.

Decreased neuronal synaptosome associated protein 29 contributes to poststroke cognitive impairment by disrupting presynaptic maintenance

Background: Poststroke cognitive impairments are common in stroke survivors, and pose a high risk of incident dementia. However, the cause of these cognitive impairments is obscure and required an investigation.

Methods: Oxygen-glucose deprivation (OGD) model and middle cerebral artery occlusion (MCAO) model were used to imitate in vitro or in vivo acute cerebral ischemia, respectively. The differentially expressed synaptosome associated protein 29 (SNAP29)-interacting proteins upon ischemia and reperfusion were analyzed with bioinformatics analysis and the results indicated that the changes of SNAP29 after acute ischemia were mainly involved in the synaptic functions. The outcomes of SNAP29 reduction were assessed with SNAP29 knockdown, which mimicked the distribution of SNAP29 along neuronal processes after acute ischemia. Using the whole-cell patch clamp recording method and transmission electron microscope, the pre-synaptic function and readily releasable pool (RRP) were observed after SNAP29 knock down. Using photogenetic manipulations and behavioral tests, the neuronal projection and cognitive functions of mice with SNAP29 knock down in hippocampus CA1 region were evaluated.

Results: It was found that SNAP29 protein levels decreased in both in vitro and in vivo ischemic models. Further, the SNAP29 reduction wasn't associated with impaired autophagy flux and neuronal survival. When SNAP29 was knocked down in primary cortical neurons, the frequency of AMPARs-mediated mEPSCs, but not the amplitude, significantly decreased. Meanwhile, the mice with SNAP29 knockdown at CA1 region of hippocampus developed an impairment in hippocampus-mPFC (middle prefrontal cortex) circuit and behavioral dysfunctions. Moreover, the size of RRP at presynaptic sites was diminished.

Conclusion: Since SNAP29 protein levels didn't significantly influence the neuronal survival and its decrease was sufficient to disturb the neural circuit via a presynaptic manner, the SNAP29-associated strategies may be an efficient target against poststroke synaptic dysfunction and cognitive deficits.

Chronic exposure to IL-6 induces a desensitized phenotype of the microglia

Background

When the homeostasis of the central nervous system (CNS) is altered, microglial cells become activated displaying a wide range of phenotypes that depend on the specific site, the nature of the activator, and particularly the microenvironment generated by the lesion. Cytokines are important signals involved in the modulation of the molecular microenvironment and hence play a pivotal role in orchestrating microglial activation. Among them, interleukin-6 (IL-6) is a pleiotropic cytokine described in a wide range of pathological conditions as a potent inducer and modulator of microglial activation, but with contradictory results regarding its detrimental or beneficial functions. The objective of the present study was to evaluate the effects of chronic IL-6 production on the immune response associated with CNS-axonal anterograde degeneration.

Methods

The perforant pathway transection (PPT) paradigm was used in transgenic mice with astrocyte-targeted IL6-production (GFAP-IL6Tg). At 2, 3, 7, 14, and 21 days post-lesion, the hippocampal areas were processed for immunohistochemistry, flow cytometry, and protein microarray.

Results

An increase in the microglia/macrophage density was observed in GFAP-IL6Tg animals in non-lesion conditions and at later time-points after PPT, associated with higher microglial proliferation and a major monocyte/macrophage cell infiltration. Besides, in homeostasis, GFAP-IL6Tg showed an environment usually linked with an innate immune response, with more perivascular CD11b⁺/CD45^high/MHCII⁺/CD86⁺ macrophages, higher T cell infiltration, and higher IL-10, IL-13, IL-17, and IL-6 production. After PPT, WT animals show a change in microglia phenotype expressing MHCII and co-stimulatory molecules, whereas transgenic mice lack this shift. This lack of response in the GFAP-IL6Tg was associated with lower axonal sprouting.

Conclusions

Chronic exposure to IL-6 induces a desensitized phenotype of the microglia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-020-02063-1.

Gut dysbiosis in stroke and its implications on Alzheimer's disease-like cognitive dysfunction

Various neurological disorders, such as stroke and Alzheimer's disease (AD), involve neuroinflammatory responses. The advent of the gut‐brain axis enhances our understanding of neurological disease progression and secondary cell death. Gut microbiomes, especially those associated with inflammation, may reflect the dysbiosis of both the brain and the gut, opening the possibility to utilize inflammatory microbiomes as biomarkers and therapeutic targets. The gut‐brain axis may serve as a contributing factor to disease pathology and offer innovative approaches in cell‐based regenerative medicine for the treatment of neurological diseases. In reviewing the pathogenesis of stroke and AD, we also discuss the effects of gut microbiota on cognitive decline and brain pathology. Although the underlying mechanism of primary cell death from either disease is clearly distinct, both may be linked to gut‐microbial dysfunction as a consequential aberration that is unique to each disease. Targeting peripheral cell death pathways that exacerbate disease symptoms, such as those arising from the gut, coupled with conventional central therapeutic approach, may improve stroke and AD outcomes.

High Serum Levels of iNOS and MIP-1α are Associated with Post-Stroke Depression

PURPOSE

Post-stroke depression (PSD) is one of the emotional disorders after the onset of stroke. Many studies have indicated that inflammatory processes can promote the occurrence and development of PSD. The purpose of our study was to explore the potential relationship between PSD and two inflammatory biomarkers: inducible nitric oxide synthase (iNOS) and macrophage inflammatory protein 1α (MIP-1α).

METHODS

In total, 80 patients diagnosed with depression after the first-ever acute ischemic stroke were enrolled in PSD group consecutively. During the same period, 40 non-depressed patients following the first-ever acute ischemic stroke and 40 healthy control subjects were recruited as non-PSD group and normal group, respectively. All participants have performed serum iNOS and MIP-1α level examination with enzyme-linked immunosorbent assay (ELISA). The severity of depressive symptoms was evaluated by the 24-item Hamilton Depression Scale (HAMD-24).

RESULTS

Serum iNOS and MIP-1α levels were significantly higher in PSD group than those in non-PSD and normal groups (P < 0.001). Serum iNOS and MIP-1α levels of PSD patients with varying degrees of depression were significantly different, serum iNOS and MIP-1α levels became higher as the depressive symptoms became more severe (P < 0.05). There was a positive correlation between the elevated levels of iNOS, MIP-1α and HAMD scores (r = 0.262, 0.209, P < 0.05). Logistic regression analysis showed that both serum iNOS and MIP-1α levels were independently associated with PSD (OR = 2.790, 95% CI: 0.712-10.933, P < 0.05 and OR = 1.922, 95% CI: 0.648-9.815, P < 0.05, respectively) after adjustment for possible relevant confounders.

CONCLUSION

High serum levels of iNOS and MIP-1α were found to be associated with the development of PSD and closely related to its severity.

Novel insights toward human stroke-related epigenetics: circular RNA and its impact in poststroke processes

Aim: Circular RNAs (circRNAs) are dysregulated in complex diseases, so we investigated their global expression profile in stroke. Material & methods: Public RNA-Seq data of human ischemic stroke lesion tissues and controls were used to perform the global expression analysis. Target RNA binding proteins and microRNAs were predicted in silico. Functional enrichment analysis was performed to infer the circRNAs' potential roles. Results: We found that circRNAs are potentially involved in synaptic components and transmission, inflammation and ataxia. An integrative analysis revealed that hsa_circ_0078299 and FXN may be major players in the molecular stroke-context. Conclusion: Our results suggest a broad involvement of circRNAs in some stroke-related processes, indicating their potential as therapeutic targets to allow neuroprotection and brain recovery.

Review of the Protective Effects of Statins on Cognition

Elevated cholesterol is a major risk factor in the development of cardiovascular disease. Statins have proven to be effective in lowering low-density lipoprotein cholesterol as well as the incidence of cardiovascular events. As a result, statins are widely prescribed in the United States, with an estimated 35 million patients on statins. Many of these patients are older than age 65 and suffer from various comorbidities, including mild to severe cognitive impairment. Early studies looking at the effects of statins on cognition have shown that statin use may lead to mild reversible cognitive decline, although long-term studies have shown inconclusive findings. In recent years, studies have shown that the use of statins in certain groups of patients may lead to a reduction in the rate of cognitive decline. One hypothesis for this finding is that statin use can reduce the risk of cerebrovascular disease which may, in turn, reduce the risk of mild cognitive decline and dementia. With numerous patients currently prescribed statins and the likelihood that more patients will be prescribed the medication in the coming years, it is important to review the current literature to determine the association between statin use and cognitive decline, as well as determine how statins may be beneficial in preventing cognitive decline.

Interleukin-17 and ischaemic stroke

Interleukin-17 (IL-17) is a cytokine family that includes 6 members, IL-17A through IL-17F, most of them are reported to have pro-inflammatory role. Through binding to their receptors (IL-17Rs), IL-17 activates the intracellular signalling pathways to play an important role in autoimmune diseases, including rheumatoid arthritis (RA) and multiple sclerosis (MS). Ischaemic stroke is a complex pathophysiological process mainly caused by regional cerebral ischaemia. Inflammatory factors contribute to the physiological process of stroke that leads to poor prognosis. IL-17 plays a crucial role in promoting inflammatory response and inducing secondary injury in post-stroke. Though immune cells and inflammatory factors have been reported to be involved in the damage of stroke, the functions of IL-17 in this process need to be elucidated. This review focuses on the pathological modulation and the mechanism of IL-17 family in ischaemic stroke and seeking to provide new insights for future therapies.

Communications Between Peripheral and the Brain-Resident Immune System in Neuronal Regeneration After Stroke

Cerebral ischemia may cause irreversible neural network damage and result in functional deficits. Targeting neuronal repair after stroke potentiates the formation of new connections, which can be translated into a better functional outcome. Innate and adaptive immune responses in the brain and the periphery triggered by ischemic damage participate in regulating neural repair after a stroke. Immune cells in the blood circulation and gut lymphatic tissues that have been shaped by immune components including gut microbiota and metabolites can infiltrate the ischemic brain and, once there, influence neuronal regeneration either directly or by modulating the properties of brain-resident immune cells. Immune-related signalings and metabolites from the gut microbiota can also directly alter the phenotypes of resident immune cells to promote neuronal regeneration. In this review, we discuss several potential mechanisms through which peripheral and brain-resident immune components can cooperate to promote first the resolution of neuroinflammation and subsequently to improved neural regeneration and a better functional recovery. We propose that new insights into discovery of regulators targeting pro-regenerative process in this complex neuro-immune network may lead to novel strategies for neuronal regeneration.

AIM2 inflammasome contributes to brain injury and chronic post-stroke cognitive impairment in mice

Although over one-third of stroke patients may develop post-stroke cognitive impairment (PSCI), the mechanisms underlying PSCI remain unclear. We explored here, the involvement of post-stroke inflammasomes in long-term PSCI development, using a 45 min-middle cerebral artery occlusion (MCAO)/reperfusion-induced PSCI model. Immunohistological assessment on day 1, 3, and 7 was followed by cognitive function test 28 days post-stroke. Evaluation of inflammasome sensor gene expression in aged mouse brains showed dominant expression of absent in melanoma 2 (Aim2) in 6-, 12-, and 18-month-old mouse brains. AIM2 mRNA and protein increased until 7 days post-stroke. PSCI decreased anxiety in elevated plus maze test and impaired spatial learning and memory functions in Morris water maze test 28 days post-stroke. AIM2 and other inflammasome subunit immunoreactivities, including those for caspase-1, interleukin (IL)-1β, and IL-18, were higher in the hippocampus and cortex of the PSCI than in those of the sham group 7 days post-stroke. AIM2 immunoreactivity of the PSCI group was primarily co-localized with Iba-1 (microglial marker) and CD31 (endothelial cell marker) immunoreactivities but not NeuN (neuronal marker) and GFAP (astrocyte marker) immunoreactivities, suggesting that microglia or endothelial cell-induced AIM2 production mediated PSCI pathogenesis. Additionally, inflammasome-induced pyroptosis might contribute to acute and chronic neuronal death after stroke. AIM2 knockout (KO) and Ac-YVAD-CMK-induced caspase-1 inhibition in mice significantly improved cognitive function and reversed brain volume in the hippocampus relative to those in stroke mice. Conclusively, AIM2 inflammasome-mediated inflammation and pyroptosis likely aggravated PSCI; therefore, targeting and controlling AIM2 inflammasome could potentially treat PSCI.

Radiotherapy Exposure in Cancer Patients and Subsequent Risk of Stroke: A Systematic Review and Meta-Analysis

Background: Cancer patients who have undergone radiotherapy may have an increased risk of subsequent stroke. A clear and detailed understanding of this risk has not been established. Methods: A search for research articles published from January 1990 to November 2017 in the English language was conducted. Subsequent stroke risk in cancer survivors was compared using relative risk (RR) and 95% confidence intervals (CI) according to whether or not radiotherapy was given. Results: A total of 12 eligible studies were identified including 57,881 total patients. All studies were retrospective, as no prospective studies were identified. The meta-analysis revealed a higher overall risk of subsequent stroke in cancer survivors/patients given radiotherapy compared to those not given radiotherapy (RR: 2.09, 95% CI: 1.45, 3.16). In addition, compared to patients not given radiotherapy, there was an increased risk of subsequent stroke for radiotherapy treated patients with Hodgkin's lymphoma (RR: 2.81, 95% CI: 0.69, 4.93) or head/neck/brain/nasopharyngeal cancer (RR: 2.16, 95% CI: 1.16, 3.16), for patients younger than 40 years (RR: 3.53, 95% CI: 2.51, 4.97) or aged 40-49 years (RR: 1.23, 95% CI: 1.09, 1.45) and for patients treated in Asia (RR: 1.88, 95% CI: 1.48, 2.29), the United States (RR: 1.62, 95% CI: 1.01, 2.23), or in Europe (RR: 4.11, 95% CI 2.62, 6.45). Conclusions: The available literature indicates an approximate overall doubling of the subsequent stroke risk in cancer patients given radiotherapy. The elevated risk was generally statistically significant according to cancer type, baseline patient age and region or country where treatment was given. Caution is required in interpreting these findings due to the heterogeneity of populations represented and lack of standardization and completeness across published studies. Further, if real, we cannot conclude the extent to which patient, treatment and/or investigational factors are responsible for this apparent elevated risk. An objective and more detailed understanding of the risks of radiotherapy, and how to prevent them, is urgently required. It is the responsibility of all who provide cancer services to ensure that the experience of all their patients is documented and analyzed using quality registries.

Effect of exposure to low doses of ozone on interleukin 17A expression during progressive neurodegeneration in the rat hippocampus

INTRODUCTION

Chronic exposure to low doses of ozone causes oxidative stress and loss of regulation of the inflammatory response, leading to progressive neurodegeneration.

OBJECTIVE

We studied the effect of chronic exposure to low doses of ozone on IL-17A concentration and expression in neurons, microglia, astrocytes, and T cells in the rat hippocampus.

METHODS

We used 72 Wistar rats, divided into 6 groups (n=12): a control group (no ozone exposure) and 5 groups exposed to ozone (0.25ppm, 4h daily) for 7, 15, 30, 60, and 90 days. We processed 6 rats from each group to quantify IL-17A by ELISA; the remaining 6 were processed for immunohistochemistry (against IL-17A and GFAP, Iba1, NeuN, and CD3).

RESULTS

The ELISA study data showed a significant increase in IL-17A concentrations in the 7-, 15-, 30-, and 60-day exposure groups, with regard to the control group (P<.05). Furthermore, they indicate that hippocampal neurons were the cells showing greatest immunoreactivity against IL-17A between 60 and 90 days of exposure to ozone; we also observed an increase in activated astrocytes in the 30- and 60-day exposure groups.

CONCLUSION

Exposure to ozone in rats induces an increase in IL-17A expression, mainly in hippocampal neurons, accompanied by hippocampal astrocyte activation during chronic neurodegeneration, similar to that observed in Alzheimer disease in humans.

Chronic colitis induces meninges traffic of gut-derived T cells, unbalances M1 and M2 microglia/macrophage and increases ischemic brain injury in mice

Ischemic stroke is one of the most common diseases leading to death and is the primary cause of physical handicap. Recent studies have reported that chronic colitis increases the risk of ischemic stroke, but it is unknown whether chronic colitis participates in ischemic brain injury directly. A combined mouse model of chronic colitis induced by dextran sodium sulfate (DSS) and ischemic stroke induced by photochemical infarction was used in this study. We demonstrated that chronic colitis significantly increased the infarction volume, activated microglia/macrophage numbers, proliferation of M1 microglia/macrophage, non-gut-derived CD4+ T lymphocyte penetration and decreased neuron numbers in the peri-infarction at 7 d after stroke. Furthermore, gut-derived CD4+ T cell accumulation on the meninges was observed at 7 d after stroke. In addition, selective depletion of meningeal macrophages resulted in a reduction of infarction volume and the non-gut-derived CD4+ T lymphocyte penetration. We concluded that chronic colitis exacerbated ischemic stroke by promoting CD4+ T cell migration from the gut to the meninges and disequilibrium of M1 and M2 microglia/macrophages. We speculated that the gut-derived CD4+ T cells may interact with meningeal macrophages and result in non-gut-derived CD4+ T lymphocyte infiltration that aggravated brain injury in ischemic stroke.

Sensorimotor stroke alters hippocampo-thalamic network activity

Many stroke survivors experience persisting episodic memory disturbances. Since hippocampal and para-hippocampal areas are usually spared from the infarcted area, alterations of memory processing networks remote from the ischemic brain region might be responsible for the observed clinical symptoms. To pinpoint changes in activity of hippocampal connections and their role in post-stroke cognitive impairment, we induced ischemic stroke by occlusion of the middle cerebral artery (MCAO) in adult rats and analyzed the functional and structural consequences using activity-dependent manganese (Mn²⁺) enhanced MRI (MEMRI) along with behavioral and histopathological analysis. MCAO caused stroke lesions of variable extent along with sensorimotor and cognitive deficits. Direct hippocampal injury occurred in some rats, but was no prerequisite for cognitive impairment. In healthy rats, injection of Mn²⁺ into the entorhinal cortex resulted in distribution of the tracer within the hippocampal subfields into the lateral septal nuclei. In MCAO rats, Mn²⁺ accumulated in the ipsilateral thalamus. Histopathological analysis revealed secondary thalamic degeneration 28 days after stroke. Our findings provide in vivo evidence that remote sensorimotor stroke modifies the activity of hippocampal-thalamic networks. In addition to potentially reversible alterations in signaling of these connections, structural damage of the thalamus likely reinforces dysfunction of hippocampal-thalamic circuitries.

Anti-IL17 treatment ameliorates Down syndrome phenotypes in mice

Down syndrome (DS) is characterized by structural and functional anomalies that are present prenatally and that lead to intellectual disabilities. Later in life, the cognitive abilities of DS individuals progressively deteriorate due to the development of Alzheimer's disease (AD)-associated neuropathology (i.e., β-amyloid (Aβ) plaques, neurofibrillary tangles (NFTs), neurodegeneration, synaptic pathology, neuroinflammation and increased oxidative stress). Increasing evidence has shown that among these pathological processes, neuroinflammation plays a predominant role in AD etiopathology. In AD mouse models, increased neuroinflammation appears earlier than Aβ plaques and NFTs, and in DS and AD models, neuroinflammation exacerbates the levels of soluble and insoluble Aβ species, favoring neurodegeneration. The Ts65Dn (TS) mouse, the most commonly used murine model of DS, recapitulates many alterations present in both DS and AD individuals, including enhanced neuroinflammation. In this study, we observed an altered neuroinflammatory milieu in the hippocampus of the TS mouse model. Pro-inflammatory mediators that were elevated in the hippocampus of this model included pro-inflammatory cytokine IL17A, which has a fundamental role in mediating brain damage in neuroinflammatory processes. Here, we analyzed the ability of an anti-IL17A antibody to reduce the neuropathological alterations that are present in TS mice during early neurodevelopmental stages (i.e., hippocampal neurogenesis and hypocellularity) or that are aggravated in later-life stages (i.e., cognitive abilities, cholinergic neuronal loss and increased cellular senescence, APP expression, Aβ peptide expression and neuroinflammation). Administration of anti-IL17 for 5 months, starting at the age of 7 months, partially improved the cognitive abilities of the TS mice, reduced the expression of several pro-inflammatory cytokines and the density of activated microglia and normalized the APP and Aβ_1-42 levels in the hippocampi of the TS mice. These results suggest that IL17-mediated neuroinflammation is involved in several AD phenotypes in TS mice and provide a new therapeutic target to reduce these pathological characteristics.

Blood-Cerebrospinal Fluid Barrier Gradients in Mild Cognitive Impairment and Alzheimer's Disease: Relationship to Inflammatory Cytokines and Chemokines

Background: The pathophysiology underlying altered blood-cerebrospinal fluid barrier (BCSFB) function in Alzheimer's disease (AD) is unknown but may relate to endothelial cell activation and cytokine mediated inflammation. Methods: Cerebrospinal fluid (CSF) and peripheral blood were concurrently collected from cognitively healthy controls (N = 21) and patients with mild cognitive impairment (MCI) (N = 8) or AD (N = 11). The paired serum and CSF samples were assayed for a panel of cytokines, chemokines, and related trophic factors using multiplex ELISAs. Dominance analysis models were conducted to determine the relative importance of the inflammatory factors in relationship to BCSFB permeability, as measured by CSF/serum ratios for urea, creatinine, and albumin. Results: BCSFB disruption to urea, a small molecule distributed by passive diffusion, had a full model coefficient of determination (r²) = 0.35, and large standardized dominance weights (>0.1) for monocyte chemoattractant protein-1, interleukin (IL)-15, IL-1rα, and IL-2 in serum. BCSFB disruption to creatinine, a larger molecule governed by active transport, had a full model r² = 0.78, and large standardized dominance weights for monocyte inhibitor protein-1b in CSF and tumor necrosis factor-α in serum. BCSFB disruption to albumin, a much larger molecule, had a full model r² = 0.62, and large standardized dominance weights for IL-17a, interferon-gamma, IL-2, and VEGF in CSF, as well IL-4 in serum. Conclusions: Inflammatory proteins have been widely documented in the AD brain. The results of the current study suggest that changes in BCSFB function resulting in altered permeability and transport are related to expression of specific inflammatory proteins, and that the shifting distribution of these proteins from serum to CSF in AD and MCI is correlated with more severe perturbations in BCSFB function.

PR-957 mediates neuroprotection by inhibiting Th17 differentiation and modulating cytokine production in a mouse model of ischaemic stroke

Acute ischaemic stroke can induce secondary brain injury by activating an inflammatory response that contributes to clinical impairment. As a specific inhibitor of the immunoproteasome subunit low molecular weight polypeptide 7 (LMP7), PR-957 may participate in regulating pathophysiological and inflammatory responses in multiple diseases of the central nervous system (CNS). We investigated the neuroprotective properties of PR-957 in a mouse model of stroke, induced by middle cerebral artery occlusion (MCAO). After MCAO and injections of PR-957 or vehicle, we evaluated mice behaviourally using modified Neurological Severity Scores (mNSS) and sensorimotor tests, including the adhesive-removal test, a foot-fault test and an inclined plane test. Infarct volume was measured 24 and 72 h after MCAO. Infiltration by different lymphocyte subpopulations was evaluated by flow cytometry and immunofluorescent staining of brain tissue from the penumbral area. Quantitative real-time polymerase chain reaction analysis and enzyme-linked immunosorbent assay were used to measure the expression of proinflammatory cytokines: interkeukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL-17A, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, granulocyte colony-stimulating factor (GCSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Expression of phosphorylated signal transducer and activator of transcription 3 (pSTAT-3) protein levels in brain was measured by immunoblot. MCAO mice treated with PR-957 showed a significant decrease in infarct volume and had mild neurological deficits compared to vehicle-treated mice. PR-957 administration also significantly decreased IL-1β, IL-6, IL-12, IL-17A and TNF-α. PR-957 provides neuroprotection via inhibiting T lymphocyte infiltration and decreasing T helper type 17 (Th17) cell differentiation in MCAO mice, which may result from the reduced expression of pSTAT-3. The neuroprotective effect of PR-957 indicates its potential utility as anti-inflammatory therapy for ischaemic stroke.

Stroke among Rheumatoid Arthritis Patients: Does Age Matter? A Real-Life Study

BACKGROUND/AIMS

Rheumatoid arthritis (RA) is a chronic, debilitating autoimmune disease that affects the joints and it is known to be associated with cardiovascular morbidity. However, the association between RA and stroke among different age groups has not been explored. The objective of our study was to evaluate the association between RA and stroke in different age strata.

METHODS

Cross-sectional study, utilizing the database of Israel's largest healthcare provider. The proportion of stroke was compared between patients diagnosed with RA and age- and gender-matched controls. The study sample was divided into 2 age groups: young (≤65 years) and elderly (>65 years). Multivariable analysis was performed using logistic regression.

RESULTS

The study included 11,782 RA patients and 57,973 age- and gender-matched controls. RA patients, primarily young, had more cardiovascular risk factors than controls. Stroke rates were significantly elevated among young RA patients in comparison with controls (3.74 vs. 2.20%, respectively, p < 0.001). In multivariate analysis, RA was found to be independently associated with stroke (OR 1.18, 95% CI 1.09-1.28).

CONCLUSION

RA is independently associated with stroke, especially among RA patients under 65 years, for whom cardiovascular risk factors were more prominent. Physicians should advise RA patients to manage their risk factors strictly.

Impact of aging immune system on neurodegeneration and potential immunotherapies

The interaction between the nervous and immune systems during aging is an area of avid interest, but many aspects remain unclear. This is due, not only to the complexity of the aging process, but also to a mutual dependency and reciprocal causation of alterations and diseases between both the nervous and immune systems. Aging of the brain drives whole body systemic aging, including aging-related changes of the immune system. In turn, the immune system aging, particularly immunosenescence and T cell aging initiated by thymic involution that are sources of chronic inflammation in the elderly (termed inflammaging), potentially induces brain aging and memory loss in a reciprocal manner. Therefore, immunotherapeutics including modulation of inflammation, vaccination, cellular immune therapies and "protective autoimmunity" provide promising approaches to rejuvenate neuroinflammatory disorders and repair brain injury. In this review, we summarize recent discoveries linking the aging immune system with the development of neurodegeneration. Additionally, we discuss potential rejuvenation strategies, focusing aimed at targeting the aging immune system in an effort to prevent acute brain injury and chronic neurodegeneration during aging.

The role of carbon monoxide and heme oxygenase in the prevention of sickle cell disease vaso-occlusive crises

Sickle Cell Disease (SCD) is a painful, lifelong hemoglobinopathy inherited as a missense point mutation in the hemoglobin (Hb) beta-globin gene. This disease has significant impact on quality of life and mortality, thus a substantial medical need exists to reduce the vaso-occlusive crises which underlie the pathophysiology of the disease. The concept that a gaseous molecule may exert biological function has been well known for over one hundred years. Carbon monoxide (CO), although studied in SCD for over 50 years, has recently emerged as a powerful cytoprotective biological response modifier capable of regulating a host of physiologic and therapeutic processes that, at low concentrations, exerts key physiological functions in various models of tissue inflammation and injury. CO is physiologically generated by the metabolism of heme by the heme oxygenase enzymes and is measurable in blood. A substantial amount of preclinical and clinical data with CO have been generated, which provide compelling support for CO as a potential therapeutic in a number of pathological conditions. Data underlying the therapeutic mechanisms of CO, including in SCD, have been generated by a plethora of in vitro and preclinical studies including multiple SCD mouse models. These data show CO to have key signaling impacts on a host of metallo-enzymes as well as key modulating genes that in sum, result in significant anti-inflammatory, anti-oxidant and anti-apoptotic effects as well as vasodilation and anti-adhesion of cells to the endothelium resulting in preservation of vascular flow. CO may also have a role as an anti-polymerization HbS agent. In addition, considerable scientific data in the non-SCD literature provide evidence for a beneficial impact of CO on cerebrovascular complications, suggesting that in SCD, CO could potentially limit these highly problematic neurologic outcomes. Research is needed and hopefully forthcoming, to carefully elucidate the safety and benefits of this potential therapy across the age spectrum of patients impacted by the host of pathophysiological complications of this devastating disease.

Identification of IL-17A-derived neural cell type and dynamic changes of IL-17A in serum/CSF of mice with ischemic stroke

BACKGROUND

Interleukin (IL)-17A was reported to be involved in the development of post-ischemic stroke inflammatory response and functional recovery. However, the IL-17A dynamic changes in serum/cerebrospinal fluid (CSF) and its role in neuronal injury following ischemic stroke are unclear.

METHODS

In vivo ischemic stroke was induced by 1 h of middle cerebral artery occlusion (MCAO) and 6 h-7 d reperfusion (R) in mice, while in vitro stroke was induced by 1 h oxygen-glucose deprivation (OGD)/24 h reoxygenation (R) in cultured cortical neurons. Enzyme-linked immunosorbent assay (ELISA) and double-labeled immunofluorescence of IL-17A with neuron (NeuN), astrocyte (GFAP) and microglia (Iba-1)-specific markers were used to determine the IL-17A levels in serum/CSF and neural cell type.

RESULTS

The ELISA results showed that IL-17A significantly increased both in peri-infarct region (p < 0.001) and CSF (p < 0.05) following 1 h MCAO/R 12 h. The levels of IL-17A in serum increased at R 1 d (p < 0.05) and peaked at R 3 d (p < 0.001) after 1 h MCAO. Immunofluorescent staining demonstrated that IL-17A co-localized with GFAP in peri-infarct regions. In addition, recombinant rIL-17A could aggravate ischemic injuries at dose-dependent manner in 1 h OGD/R 24 h-treated neurons companying with the increase of IL-17A receptor il-17RA mRNA (p < 0.001) and IL-17R protein levels.

CONCLUSION

We firstly reported astrocytic IL-17A peaks in CSF within 12 h and in serum at 3 d reperfusion after ischemic stroke. IL-17A may exaggerate neuronal injuries through its receptor IL-17R at early stage of ischemic stroke.

Peripheral inflammatory markers indicate microstructural damage within periventricular white matter hyperintensities in Alzheimer's disease: A preliminary report

Introduction

White matter hyperintensities (WMH) presumed to reflect cerebral small vessel disease and increased peripheral inflammatory markers are found commonly in Alzheimer's disease (AD), but their interrelationships remain unclear.

Methods

Inflammatory markers were assayed in 54 elderly participants (n = 16 with AD). Periventricular WMH were delineated from T1, T2/proton density, and fluid-attenuated magnetic resonance imaging using semiautomated fuzzy lesion extraction and coregistered with maps of fractional anisotropy (FA), a measure of microstructural integrity assessed using diffusion tensor imaging.

Results

Mean FA within periventricular WMH was associated with an inflammatory factor consisting of interleukin (IL)-1β, tumor necrosis factor, IL-10, IL-21, and IL-23 in patients with AD (ρ = −0.703, P = .002) but not in healthy elderly (ρ = 0.217, P = .190). Inflammation was associated with greater FA in deep WMH in healthy elderly (ρ = 0.425, P = .008) but not in patients with AD (ρ = 0.174, P = .520).

Discussion

Peripheral inflammatory markers may be differentially related to microstructural characteristics within the white matter affected by cerebral small vessel disease in elders with and without AD.

Is adjunctive treatment with medication of liver-soothing-oriented method beneficial for depression after cerebrovascular accident?: A PRISMA-compliant meta-analysis

BACKGROUND

Adjunctive treatment with medication of liver-soothing-oriented method (MLSM) is one of the most commonly used approaches for subjects with depression after cerebrovascular accident (DCVA) in China. The purpose of this meta-analysis was to evaluate the outcome of MLSM treatment in subjects with DCVA using relevant published literature.

METHODS

The PubMed, Cochrane Library, Embase, Chinese databases of China National Knowledge Infrastructure, WanFang, Sinomed, and VIP were used to collect all publications until March 2016. Randomized controlled trials comparing treatments with and without MLSM for subjects with DCVA were included. The quality of each publication was assessed based on the recent Handbook (5.1 version) for Cochrane Reviewers. Cochrane Collaboration's software RevMan 5.3 software was applied for data analysis.

RESULTS

Thirty studies, including 2599 cases, were identified and collected. Adjunctive treatment with MLSM noticeably enhanced total effective rates (odds ratio 3.76; 95% confidence interval [CI] 2.92-4.85, I = 0%, P = 0.96) in comparison to non-MLSM conventional pharmacotherapy. Compared to non-MLSM treatment, the changes of Hamilton Depression Scale in adjunctive treatment with MLSM, respectively, decreased and showed beneficial effects after 3 weeks (weighted mean difference [WMD] -4.83; 95% CI -6.82 to -2.83; I = 86%, P < 0.001), 4 weeks (WMD -4.20; 95% CI -5.06 to -3.33; I = 78%, P < 0.001), 6 weeks (WMD -3.36; 95% CI -4.05 to -2.68; I = 54%, P = 0.02), 8 weeks (WMD -4.83; 95% CI -5.62 to -4.04; I = 73%, P < 0.001), and 12 weeks (WMD -2.88; 95% CI -4.09 to -1.67; I = 58%, P = 0.09). As for changes in inflammatory cytokine levels, adjunctive treatment with MLSM was associated with a significant decrease in tumor necrosis factor-α, IL-6, and interleukin-1β levels in comparison to non-MLSM treatment. Moreover, there were positive effects on score changes for National Institute of Health Stroke Scale, activities of daily living, Hamilton Anxiety Scale, Modified Edinburgh Scandinavian Stroke Scale, and Self-Rating Anxiety Scale. No serious adverse events were reported.

CONCLUSION

MLSM appears to improve symptoms of depressive disorders, enhance immediate responses, and the quality of life in subjects with DCVA. The positive action of MLSM might be potentially connected with its immunoregulating effects. More prospective trials with strict design and larger sample sizes are warranted to clarify its effectiveness and safety.

Key Immune Events of the Pathomechanisms of Early Cardioembolic Stroke: Multi-Database Mining and Systems Biology Approach

While inflammation has generally been regarded as a negative factor in stroke recovery, this viewpoint has recently been challenged by demonstrating that inflammation is a necessary and sufficient factor for regeneration in the zebrafish brain injury model. This close relationship with inflammation suggests that a re-examination of the immune system’s role in strokes is necessary. We used a systems biology approach to investigate the role of immune-related functions via their interactions with other molecular functions in early cardioembolic stroke. Based on protein interaction models and on microarray data from the blood of stroke subjects and healthy controls, networks were constructed to delineate molecular interactions at four early stages (pre-stroke, 3 h, 5 h and 24 h after stroke onset) of cardioembolic stroke. A comparative analysis of functional networks identified interactions of immune-related functions with other molecular functions, including growth factors, neuro/hormone and housekeeping functions. These provide a potential pathomechanism for early stroke pathophysiology. In addition, several potential targets of miRNA and methylation regulations were derived based on basal level changes observed in the core networks and literature. The results provide a more comprehensive understanding of stroke progression mechanisms from an immune perspective and shed light on acute stroke treatments.

Mapping inflammation onto mood: Inflammatory mediators of anhedonia

Evidence supports inflammatory involvement in mood and cognitive symptoms across psychiatric, neurological and medical disorders; however, inflammation is not a sensitive or specific characteristic of these diagnoses. The National Institute of Mental Health Research Domain Criteria (RDoC) ask for a shift away from symptom-based diagnoses toward a transdiagnostic neurobiological focus in the study of brain illnesses. The RDoC matrix may provide a useful framework for integrating the effects of inflammation on brain function. Based on preclinical and clinical findings, relevant relationships span negative and positive valence systems, cognitive systems, systems for social processes and arousal/regulatory systems. As an exemplar, we consider the psychopathological domain of anhedonia, conceptualizing the relevance of inflammation (e.g., cellular immunity) and downstream processes (e.g., indoleamine 2,3-dioxygenase activation and oxidative inactivation of tetrahydrobiopterin) across RDoC units of analysis (e.g., catecholamine neurotransmitter molecules, nucleus accumbens medium spiny neuronal cells, dopaminergic mesolimbic and mesocortical reward circuits, animal paradigms, etc.). We discuss implications across illnesses affecting the brain, including infection, major depressive disorder, stroke, Alzheimer's disease and type 2 diabetes.