CNS and peripheral immunity in cerebral ischemia: partition and interaction

Huang-Lian-Jie-Du decoction inhibits CD4+ T cell infiltration into CNS in MCAO rats by regulating BBB

BACKGROUND

Stroke, especially ischemic stroke (IS), represents a major global health challenge due to its high incidence, disability, mortality, recurrence, and economic impact. The limited therapeutic window for thrombolysis underscores the need for new treatments. The blood-brain barrier (BBB), which protects the brain, becomes compromised following ischemia-reperfusion injury, allowing peripheral immune cell infiltration and subsequent neuroinflammation. Huang-Lian-Jie-Du Decoction (HLJDT), a traditional formula with significant neuroprotective effects demonstrated in preliminary studies and literature reviews, has not yet been fully explored for its potential to inhibit peripheral immune cell infiltration through BBB protection.

PURPOSE

This study aims to: (1) Evaluate the efficacy of HLJDT in treating MCAO. (2) Observe the regulatory effect of HLJDT on the infiltration of CD4+ T cells into the central nervous system. (3) Investigate the effect of HLJDT on the Wnt/β-Catenin Signaling Pathway.

METHODS

A focal MCAO reperfusion model will be used to evaluate HLJDT's effects on neurological function (Zea Longa and Garcia scores), infarction volume (TTC staining), and pathological changes (HE and NISSL staining). Immune-inflammatory responses will be assessed using ELISA for cytokines, flow cytometry for T lymphocyte distribution, and immunofluorescence staining for CD4+ T cell infiltration. The interaction of T cell antigens (LFA-1) and endothelial adhesion molecules (ICAM-1) will be studied with ELISA and immunofluorescence. BBB protection will be evaluated with Evans blue staining and transmission electron microscopy. Mechanisms of T cell infiltration will be examined using transmission electron microscopy and Western blotting (WB) for key proteins. Additionally, the impact of HLJDT on the Wnt/β-catenin pathway will be assessed with WB.

RESULTS

HLJDT significantly improves neurological scores, reduces infarction volume, and mitigates pathological damage. It balances CD4+ T cell responses by inhibiting pro-inflammatory cytokines and enhancing anti-inflammatory ones, reducing CD4+ T cell CNS infiltration. HLJDT inhibits LFA-1/ICAM-1 interactions. It can also inhibit CD4+ T cell infiltration by repairing paracellular and transcellular structures of the BBB, with the Wnt/β-catenin signaling pathway playing a key role in this process.

CONCLUSION

We have innovatively demonstrated for the first time that HLJDT can regulate the balance between peripheral and central immune inflammation. It inhibits LFA-1/ICAM-1-mediated cell adhesion and, by modulating the Wnt/β-catenin pathway, improves the paracellular and transcellular structures of the blood-brain barrier, thereby suppressing CD4+ T cell infiltration and providing multifaceted protective effects for MCAO rats.

Chitinase-3-like-1: a multifaceted player in neuroinflammation and degenerative pathologies with therapeutic implications

Chitinase-3-like-1 (CHI3L1) is an evolutionarily conserved protein involved in key biological processes, including tissue remodeling, angiogenesis, and neuroinflammation. It has emerged as a significant player in various neurodegenerative diseases and brain disorders. Elevated CHI3L1 levels have been observed in neurological conditions such as traumatic brain injury (TBI), Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), Creutzfeldt-Jakob disease (CJD), multiple sclerosis (MS), Neuromyelitis optica (NMO), HIV-associated dementia (HAD), Cerebral ischemic stroke (CIS), and brain tumors. This review explores the role of CHI3L1 in the pathogenesis of these disorders, with a focus on its contributions to neuroinflammation, immune cell infiltration, and neuronal degeneration. As a key regulator of neuroinflammation, CHI3L1 modulates microglia and astrocyte activity, driving the release of proinflammatory cytokines that exacerbate disease progression. In addition to its role in disease pathology, CHI3L1 has emerged as a promising biomarker for the diagnosis and monitoring of brain disorders. Elevated cerebrospinal fluid (CSF) levels of CHI3L1 have been linked to disease severity and cognitive decline, particularly in AD and MS, highlighting its potential for clinical diagnostics. Furthermore, therapeutic strategies targeting CHI3L1, such as small-molecule inhibitors and neutralizing antibodies, have shown promise in preclinical studies, demonstrating reduced neuroinflammation, amyloid plaque accumulation, and improved neuronal survival. Despite its therapeutic potential, challenges remain in developing selective and safe CHI3L1-targeted therapies, particularly in ensuring effective delivery across the blood-brain barrier and mitigating off-target effects. This review addresses the complexities of targeting CHI3L1, highlights its potential in precision medicine, and outlines future research directions aimed at unlocking its full therapeutic potential in treating neurodegenerative diseases and brain pathologies.

MRS3997, a dual adenosine A2A/A2B receptor agonist, reduces brain ischemic damage and alleviates neuroinflammation in rats

The endogenous neuromodulator adenosine is massively released during hypoxic/ischemic insults and differentially modulates post-ischemic damage depending on the expression and recruitment of its four metabotropic receptor subtypes, namely A1, A2A, A2B and A3 receptors (A1Rs, A2ARs, A2BRs and A3Rs). We previously demonstrated, by using a model of transient middle cerebral artery occlusion (tMCAo) in rats, that selective activation of A2ARs, as well as A2BRs, ameliorates post-ischemic brain damage in contrast to neuroinflammation. In the present study, we investigated whether the multitarget nucleoside MRS3997, a full agonist at both A2ARs and A2BRs, would afford higher neuroprotection in post-ischemic damage. Chronic systemic treatment with MRS3997 reduced neurological deficit, body weight loss and infarct volume in the cortex and striatum measured 7 days after ischemia. The dual agonist counteracted neuronal loss, reduced myelin damage, and prevented morphological changes indicative of microglia and astrocyte activation. Finally, MRS3997 shifted plasma cytokine levels to an anti-inflammatory profile. These effects were preceded, at 2 days after the insult, by a reduced granulocyte infiltration in the ischemic cortex and, differently from what was observed with selective A2AR or A2BR agonism, also in striatum. In summary, we demonstrate here that MRS3997, systemically administered for 7 days after tMCAO, protects ischemic areas from neuronal and glial damage and inhibits neuroinflammation, therefore representing an attractive strategy to ameliorate post-stroke damage and neurological symptoms.

Revolutionizing Neuroimmunology: Unraveling Immune Dynamics and Therapeutic Innovations in CNS Disorders

Neuroimmunology is reshaping the understanding of the central nervous system (CNS), revealing it as an active immune organ rather than an isolated structure. This review delves into the unprecedented discoveries transforming the field, including the emerging roles of microglia, astrocytes, and the blood-brain barrier (BBB) in orchestrating neuroimmune dynamics. Highlighting their dual roles in both repair and disease progression, we uncover how these elements contribute to the intricate pathophysiology of neurodegenerative diseases, cerebrovascular conditions, and CNS tumors. Novel insights into microglial priming, astrocytic cytokine networks, and meningeal lymphatics challenge the conventional paradigms of immune privilege, offering fresh perspectives on disease mechanisms. This work introduces groundbreaking therapeutic innovations, from precision immunotherapies to the controlled modulation of the BBB using nanotechnology and focused ultrasound. Moreover, we explore the fusion of immune modulation with neuromodulatory technologies, underscoring new frontiers for personalized medicine in previously intractable diseases. By synthesizing these advancements, we propose a transformative framework that integrates cutting-edge research with clinical translation, charting a bold path toward redefining CNS disease management in the era of precision neuroimmunology.

Integrating machine learning and single-cell transcriptomic analysis to identify potential biomarkers and analyze immune features of ischemic stroke

This study employs machine learning and single-cell transcriptome sequencing (scRNA-seq) analysis to unearth novel biomarkers and delineate the immune characteristics of ischemic stroke (IS), thereby contributing fresh insights into IS treatment strategies.Our research leverages gene expression data sourced from the GEO database. We undertake weighted gene co-expression network analysis (WGCNA) to filter pertinent genes and subsequently employ machine learning algorithms for the identification of feature genes. Concurrently, we rigorously execute quality control measures, dimensionality reduction techniques, and cell annotation on the scRNA-seq data to pinpoint differentially expressed genes (DEGs). The identification of core genes, denoted as Hub genes, among the feature genes and DEGs, is achieved through meticulous overlapping analysis. We illuminate the immune characteristics of these Hub genes using a suite of analytical tools, encompassing CIBERSORT, MCPcounter, and pseudotemporal analysis, all based on immune cell annotations and single-cell transcriptome data.Subsequently, we harness the CMap database to prognosticate potential therapeutic drugs and scrutinize their associations with the identified Hub genes. Our findings unveil robust linkages between three pivotal Hub genes-namely, RNF13, VASP, and CD163-and specific immune cell types such as T cells and neutrophils. These Hub genes predominantly manifest in macrophages and microglial cells within the scRNA-seq immune cell population, exhibiting variances across different stages of cellular differentiation. In conclusion, this study unearths highly pertinent biomarkers for IS diagnosis and elucidates IS-induced immune infiltration characteristics, thus providing a firm foundation for a comprehensive exploration of potential immune mechanisms and the identification of novel therapeutic targets for IS.

Correlation of Peripheral Blood Inflammatory Indicators to Prognosis After Intravenous Thrombolysis in Acute Ischemic Stroke: A Retrospective Study

Purpose

According to many previous studies, neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR) and hypersensitive C-reactive protein (CRP) are commonly used as important indicators to assess the prognosis of intravenous thrombolysis in AIS patients. Based on this, we used two novel biomarkers C-NLR (CRP/neutrophil-to-lymphocyte ratio) and C-LMR (CRP×lymphocyte-to-monocyte ratio) to investigate their correlation with 90-day outcomes in AIS patients after intravenous thrombolysis.

Patients and Methods

A total of 204 AIS patients who received intravenous thrombolysis at the Stroke Center of Jiangsu Province Hospital of Chinese Medicine from January 2021 to December 2022 were retrospectively included. All patients were followed up 90 days after thrombolysis to assess their prognosis. Patients with a modified Rankin scale score (mRS) of 3-6 were included in the unfavorable outcome group, and those with a score of 0-2 were included in the favorable outcome group. Logistic regression analysis, receiver operating characteristic (ROC) curve, and Kaplan-Meier survival curve were used to investigate the association between C-NLR, C-LMR, and 90-day prognosis in AIS patients treated with early intravenous thrombolysis.

Results

C-NLR (OR=1.586, 95% CI=1.098~2.291, P=0.014) and C-LMR (OR=1.099, 95% CI=1.025~1.179, P=0.008) were independent risk factors for 90-day prognosis of AIS patients treated with early intravenous thrombolysis. The higher C-NLR and C-LMR were associated with unfavorable prognosis.

Conclusion

C-NLR and C-LMR can be used as biomarkers to predict prognosis of AIS patients treated with early intravenous thrombolysis.

Updates of the role of B-cells in ischemic stroke

Ischemic stroke is a major disease causing death and disability in the elderly and is one of the major diseases that seriously threaten human health and cause a great economic burden. In the early stage of ischemic stroke, neuronal structure is destroyed, resulting in death or damage, and the release of a variety of damage-associated pattern molecules induces an increase in neuroglial activation, peripheral immune response, and secretion of inflammatory mediators, which further exacerbates the damage to the blood-brain barrier, exacerbates cerebral edema, and microcirculatory impairment, triggering secondary brain injuries. After the acute phase of stroke, various immune cells initiate a protective effect, which is released step by step and contributes to the repair of neuronal cells through phenotypic changes. In addition, ischemic stroke induces Central Nervous System (CNS) immunosuppression, and the interaction between the two influences the outcome of stroke. Therefore, modulating the immune response of the CNS to reduce the inflammatory response and immune damage during stroke is important for the protection of brain function and long-term recovery after stroke, and modulating the immune function of the CNS is expected to be a novel therapeutic strategy. However, there are fewer studies on B-cells in brain function protection, which may play a dual role in the stroke process, and the understanding of this cell is still incomplete. We review the existing studies on the mechanisms of the role of B-cells, inflammatory response, and immune response in the development of ischemic stroke and provide a reference for the development of adjuvant therapeutic drugs for ischemic stroke targeting inflammatory injury.

The inducible prostaglandin E synthase (mPGES-1) in neuroinflammatory disorders

The cyclooxygenase (COX)/prostaglandin E2 (PGE2) signaling pathway has emerged as a critical target for anti-inflammatory therapeutic development in neurological diseases. However, medical use of COX inhibitors in the treatment of various neurological disorders has been limited due to well-documented cardiovascular and cerebrovascular complications. It has been widely proposed that modulation of downstream microsomal prostaglandin E synthase-1 (mPGES-1) enzyme may provide more specificity for inhibiting PGE2-elicited neuroinflammation. Heightened levels of mPGES-1 have been detected in a variety of brain diseases such as epilepsy, stroke, glioma, and neurodegenerative diseases. Subsequently, elevated levels of PGE2, the enzymatic product of mPGES-1, have been demonstrated to modulate a multitude of deleterious effects. In epilepsy, PGE2 participates in retrograde signaling to augment glutamate release at the synapse leading to neuronal death. The excitotoxic demise of neurons incites the activation of microglia, which can become overactive upon further stimulation by PGE2. A selective mPGES-1 inhibitor was able to reduce gliosis and the expression of proinflammatory cytokines in the hippocampus following status epilepticus. A similar mechanism has also been observed in stroke, where the overactivation of microglia by PGE2 upregulated the expression and secretion of proinflammatory cytokines. This intense activation of neuroinflammatory processes triggered the secondary injury commonly observed in stroke, and blockade of mPGES-1 reduced infarction size and edema, suppressed induction of proinflammatory cytokines, and improved post-stroke well-being and cognition. Furthermore, elevated levels of PGE2 have been shown to intensify the proliferation of glioma cells, mediate P-glycoprotein expression at the blood-brain barrier (BBB) and facilitate breakdown of the BBB. For these reasons, targeting mPGES-1, the central and inducible enzyme of the COX cascade, may provide a more specific therapeutic strategy for treating neuroinflammatory diseases.

Low Lymphocyte-to-Monocyte Ratio as a Possible Predictor of an Unfavourable Clinical Outcome in Patients with Acute Ischemic Stroke after Mechanical Thrombectomy

Background

Although considerable progress has been made in the treatment of acute ischemic stroke (AIS), the clinical outcome of patients is still significantly influenced by the inflammatory response that follows stroke-induced brain injury. The aim of this study was to evaluate the potential use of complete blood count parameters, including indices and ratios, for predicting the clinical outcome in AIS patients undergoing mechanical thrombectomy (MT).

Methods

This single-centre retrospective study is consisted of 179 patients. Patient data including demographic characteristics, risk factors, clinical data, laboratory parameters on admission, and clinical outcome were collected. Based on the clinical outcome assessed at 3 months after MT by the modified Rankin Scale (mRS), patients were divided into two groups: the favourable group (mRS 0-2) and unfavourable group (mRS 3-6). Stepwise multivariate logistic regression analysis was used to detect an independent predictor of the unfavourable clinical outcome.

Results

An unfavourable clinical outcome was detected after 3 months in 101 patients (54.4%). Multivariate logistic regression analysis confirmed that the lymphocyte-to-monocyte ratio (LMR) was an independent predictor of unfavourable clinical outcome at 3 months (odds ratio = 0.761, 95% confidence interval 0.625-0.928, and P = 0.007). The value of 3.27 was chosen to be the optimal cut-off value of LMR. This value could predict the unfavourable clinical outcome with a 74.0% sensitivity and a 54.4% specificity.

Conclusion

The LMR at the time of hospital admission is a predictor of an unfavourable clinical outcome at 3 months in AIS patients after MT.

Ancient Chinese Herbal Recipe Huanglian Jie Du Decoction for Ischemic Stroke: An Overview of Current Evidence

Ischemic stroke is a major cause of mortality and neurological morbidity worldwide. The underlying pathophysiology of ischemic stroke is highly complicated and correlates with various pathological processes, including neuroinflammation, oxidative stress injury, altered cell apoptosis and autophagy, excitotoxicity, and acidosis. The current treatment for ischemic stroke is limited to thrombolytic therapy such as recombinant tissue plasminogen activator. However, tissue plasminogen activator is limited by a very narrow therapeutic time window (<4.5 hours), selective efficacy, and hemorrhagic complication. Hence, the development of novel therapies to prevent ischemic damage to the brain is urgent. Chinese herbal medicine has a long history in treating stroke and its sequela. In the past decades, extensive studies have focused on the neuroprotective effects of Huanglian Jie Du decoction (HLJDD), an ancient and classical Chinese herbal formula that can treat a wide spectrum of disorders including ischemic stroke. In this review, the current evidence of HLJDD and its bioactive components for ischemic stroke is comprehensively reviewed, and their potential application directions in ischemic stroke management are discussed.

Quantitative collateral score for the prediction of clinical outcomes in stroke patients: Better than visual grading

Objectives

To identify preoperative prognostic factors for acute ischemic stroke (AIS) patients receiving mechanical thrombectomy (MT) and compare the performance of quantitative collateral score (qCS) and visual collateral score (vCS) in outcome prediction.

Methods

Fifty-five patients with AIS receiving MT were retrospectively enrolled. qCS was defined as the percentage of the volume of collaterals of both hemispheres. Based on the dichotomous outcome assessed using a 90-day modified Rankin Scale (mRS), we compared qCS, vCS, age, sex, National Institute of Health stroke scale score, etiological subtype, platelet count, international normalized ratio, glucose levels, and low-density lipoprotein cholesterol (LDL-C) levels between favorable and unfavorable outcome groups. Logistic regression analysis was performed to determine the effect on the clinical outcome. The discriminatory power of qCS, vCS, and their combination with cofounders for determining favorable outcomes was tested with the area under the receiver-operating characteristic curve (AUC).

Results

vCS, qCS, LDL-C, and age could all predict clinical outcomes. qCS is superior over vCS in predicting favorable outcomes with a relatively higher AUC value (qCS vs. vCS: 0.81 vs. 0.74) and a higher sensitivity rate (qCS vs. vCS: 72.7% vs. 40.9%). The prediction power of qCS + LDL-C + age was best with an AUC value of 0.91, but the accuracy was just increased slightly compared to that of qCS alone.

Conclusion

Collateral scores, LDL-C and age were independent prognostic predictors for patients with AIS receiving MT; qCS was a better predictor than vCS. Furthermore, qCS + LDL-C + age offers a strong prognostic prediction power and qCS alone was another good choice for predicting clinical outcome.

A monoamine oxidase B inhibitor ethyl ferulate suppresses microglia-mediated neuroinflammation and alleviates ischemic brain injury

Microglia are the resident macrophages in the brain, which play a critical role in post-stroke neuroinflammation. Accordingly, targeting neuroinflammation could be a promising strategy to improve ischemic stroke outcomes. Ethyl ferulate (EF) has been confirmed to possess anti-inflammatory properties in several disease models, including acute lung injury, retinal damage and diabetes-associated renal injury. However, the effects of EF on microglial activation and the resolution of post-stroke neuroinflammation remains unknown. Here, we found that EF suppressed pro-inflammatory response triggered by lipopolysaccharide (LPS) stimulation in primary microglia and BV2 cell lines, as well as post-stroke neuroinflammation in an in vivo transient middle cerebral artery occlusion (tMCAO) stroke model in C57BL/6 mice, consequently ameliorating ischemic brain injury. Furthermore, EF could directly bind and inhibit the activity of monoamine oxidase B (MAO-B) to reduce pro-inflammatory response. Taken together, our study identified a MAO-B inhibitor, Ethyl ferulate, as an active compound with promising potentials for suppressing post-stroke neuroinflammation.

Regulation of microglial activation in stroke in aged mice: a translational study

Numerous neurochemical changes occur with aging and stroke mainly affects the elderly. Our previous study has found interferon regulatory factor 5 (IRF5) and 4 (IRF4) regulate neuroinflammation in young stroke mice. However, whether the IRF5-IRF4 regulatory axis has the same effect in aged brains is not known. In this study, aged (18-20-month-old), microglial IRF5 or IRF4 conditional knockout (CKO) mice were subjected to a 60-min middle cerebral artery occlusion (MCAO). Stroke outcomes were quantified at 3d after MCAO. Flow cytometry and ELISA were performed to evaluate microglial activation and immune responses. We found aged microglia express higher levels of IRF5 and lower levels of IRF4 than young microglia after stroke. IRF5 CKO aged mice had improved stroke outcomes; whereas worse outcomes were seen in IRF4 CKO vs. their flox controls. IRF5 CKO aged microglia had significantly lower levels of IL-1β and CD68 than controls; whereas significantly higher levels of IL-1β and TNF-α were seen in IRF4 CKO vs. control microglia. Plasma levels of TNF-α and MIP-1α were decreased in IRF5 CKO vs. flox aged mice, and IL-1β/IL-6 levels were increased in IRF4 CKO vs. controls. The anti-inflammatory cytokines (IL-4/IL-10) levels were higher in IRF5 CKO, and lower in IRF4 CKO aged mice vs. their flox controls. IRF5 and IRF4 signaling drives microglial pro- and anti-inflammatory response respectively; microglial IRF5 is detrimental and IRF4 beneficial for aged mice in stroke. IRF5-IRF4 axis is a promising target for developing new, effective therapeutic strategies for the cerebral ischemia.

Resolution of inflammation is disturbed in acute ischemic stroke with diabetes mellitus and rescued by resolvin D2 treatment

BACKGROUND

Inflammation plays an important role in diabetes mellitus (DM)-related acute ischemic stroke (AIS). The mechanisms of un-resolved inflammation in DM-related AIS are not fully understood. Specialized pro-resolving mediators (SPMs) are key regulators that promote resolution of inflammation. We aimed to examine resolution function in patients with AIS complicated with DM, and explore potential treatment effects of one of the SPMs, resolvin D2 (RvD2) ex vivo and in vivo.

METHODS

Cultured human macrophages, which were derived from peripheral blood mononuclear cells of AIS and none-AIS patients with or without DM, were stimulated with oxidized-low density lipoprotein (ox-LDL). Levels of SPMs and inflammatory markers were analysed, and RvD2 treatment effects were evaluated in these cells. For experiments in vivo, challenges with high fat diet and low-dose streptozotocin (STZ) were used to induce DM in C57BL/6J mice. AIS model was established by permanent middle cerebral artery occlusion (pMCAO) followed by intra-cerebroventricular injection of RvD2.

RESULTS

Compared with macrophages of AIS patients without DM, the ratios of SPMs to leukotriene B4 (LTB₄) were decreased in AIS patients with DM, accompanied by reduced expression of SPM synthesis enzyme, 15-lipoxygenase-1. Moreover, the levels of pro-inflammatory pathway markers were increased, and the macrophages were skewed to M1 polarization in AIS patients with DM. In mice, treatment with RvD2 ameliorated pMCAO-induced brain injury, neurological dysfunction, and inflammatory response. Furthermore, RvD2 rescued resolution of inflammation by promoting macrophage/microglia polarization to pro-resolving M2 phenotype ex vivo and in vivo.

CONCLUSIONS

Our data demonstrate resolution of inflammation is impaired by DM in AIS patients, implicating a novel mechanism of un-resolved inflammation in DM-related AIS. Furthermore, RvD2 promotes inflammation resolution in macrophages/microglia and protects DM-related AIS, and may thus serve as a novel therapeutic target.

An Unexplored Role for MMP-7 (Matrix Metalloproteinase-7) in Promoting Gut Permeability After Ischemic Stroke

Poststroke infections are common complications of stroke and are highly associated with poor outcomes for patients. Stroke induces profound immunodepression coupled with alterations to autonomic signaling, which together render the body more susceptible to infection from without (nosocomial/community-acquired infection) and from within (commensal bacterial infection). Critical to the hypothesis of commensal infection is the phenomenon of poststroke gut permeability and gut dysbiosis. Few studies have provided adequate explanations for the mechanisms underlying the molecular alterations that produce a more permeable gut and perturbed gut microbiota after stroke. A dysregulation in the production of matrix MMP-7 (metalloproteinase-7) may play a critical role in the progression of gut permeability after stroke. By cleaving junctional and extracellular matrix proteins, MMP-7 is capable of compromising gut barrier integrity. Because of MMP-7's unique abundance in the small intestine and its capacity to be induced in states of bacterial invasion and inflammation, along with its unique degradative capability, MMP-7 may be crucially important to the progression of gut permeability after ischemic stroke.

Identification of potential regulating effect of baicalin on NFκB/CCL2/CCR2 signaling pathway in rats with cerebral ischemia by antibody-based array and bioinformatics analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Baicalin is one of the major bioactive compounds extracted from the root of Scutellaria baicalensis Georgi, which was used to treat cerebral ischemia for thounds of years. However, its biological mechanisms remains to be further explored.

AIM OF THE REVIEW

This study aims to identify potential biological mechanisms of baicalin against cerebral ischemia combining antibody-based array and bioinformatics analysis.

METHODS

A rat model of middle cerebral artery occlusion (MCAO) was constructed. Sprague-Dawley rats were randomly divided into three groups: control group, ischemic model group, and baicalin 100 mg/kg treatment group respectively. Bederson score and 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining were examined to evaluate the pharmacodynamics of baicalin treatment. Antibody-based array technology, enzyme linked immunosorbent assay (ELISA), western-blot, molecular docking, transcription factor perdiction, hematoxylin and eosin (H&E), and immunofluorescence staining were used to study the regulation of baicalin on inflammatory response after cerebral ischemia in vivo. LPS-induced RAW 264.7 macrophage inflammation model was prepared to observe the anti-inflammatory effect of baicalin in vitro.

RESULTS

Baicalin (100 mg/kg) reduced neurological injury score, cerebral infarction volume, and necrotic cells in MCAO rats. Baicalin inhibited the expression of CCL2, and reduced the phosphorylation levels of p65, IκBα protein and down-regulated level of CCR2. Besides, baicalin could bond to CCR2 directly, which prevented CCL2 from binding to CCR2. Furthermore, baicalin down-regulated the number of monocytes in the peripheral blood and improved the spleen index post-cerebral ischemia. In vitro, baicalin significantly inhibited the secretion of NO, IL6, TNFα, and CCL2 in macrophages and promoted the secretion of IL13, IFNG, and IL1a.

CONCLUSIONS

Baicalin inhibited cerebral ischemia-induced activation of the NFκB/CCL2/CCR2 pathway with multiple target effect. These data promote the therapeutic utilization of baicalin in preventing cerebral ischemia clinically.

Sepsis-Exacerbated Brain Dysfunction After Intracerebral Hemorrhage

Sepsis susceptibility is significantly increased in patients with intracerebral hemorrhage (ICH), owing to immunosuppression and intestinal microbiota dysbiosis. To date, ICH with sepsis occurrence is still difficult for clinicians to deal with, and the mortality, as well as long-term cognitive disability, is still increasing. Actually, intracerebral hemorrhage and sepsis are mutually exacerbated via similar pathophysiological mechanisms, mainly consisting of systemic inflammation and circulatory dysfunction. The main consequence of these two processes is neural dysfunction and multiple organ damages, notably, via oxidative stress and neurotoxic mediation under the mediation of central nervous system activation and blood-brain barrier disruption. Besides, the comorbidity-induced multiple organ damages will produce numerous damage-associated molecular patterns and consequently exacerbate the severity of the disease. At present, the prospective views are about operating artificial restriction for the peripheral immune system and achieving cross-tolerance among organs via altering immune cell composition to reduce inflammatory damage.

Inducible Prostaglandin E Synthase as a Pharmacological Target for Ischemic Stroke

As the inducible terminal enzyme for prostaglandin E2 (PGE2) synthesis, microsomal PGE synthase-1 (mPGES-1) contributes to neuroinflammation and secondary brain injury after cerebral ischemia via producing excessive PGE2. However, a proof of concept that mPGES-1 is a therapeutic target for ischemic stroke has not been established by a pharmacological strategy mainly due to the lack of drug-like mPGES-1 inhibitors that can be used in relevant rodent models. To this end, we recently developed a series of novel small-molecule compounds that can inhibit both human and rodent mPGES-1. In this study, blockade of mPGES-1 by our several novel compounds abolished the lipopolysaccharide (LPS)-induced PGE2 and pro-inflammatory cytokines interleukin 1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α) in mouse primary brain microglia. Inhibition of mPGES-1 also decreased PGE2 produced by neuronal cells under oxygen-glucose deprivation (OGD) stress. Among the five enzymes for PGE2 biosynthesis, mPGES-1 was the most induced one in cerebral ischemic lesions. Systemic treatment with our lead compound MPO-0063 (5 or 10 mg/kg, i.p.) in mice after transient middle cerebral artery occlusion (MCAO) improved post-stroke well-being, decreased infarction and edema, suppressed induction of brain cytokines (IL-1β, IL-6, and TNF-α), alleviated locomotor dysfunction and anxiety-like behavior, and reduced the long-term cognitive impairments. The therapeutic effects of MPO-0063 in this proof-of-concept study provide the first pharmacological evidence that mPGES-1 represents a feasible target for delayed, adjunct treatment - along with reperfusion therapies - for acute brain ischemia.

Extracellular Matrix-Mimetic Hydrogels for Treating Neural Tissue Injury: A Focus on Fibrin, Hyaluronic Acid, and Elastin-Like Polypeptide Hydrogels

Neurological and functional recovery is limited following central nervous system injury and severe injury to the peripheral nervous system. Extracellular matrix (ECM)-mimetic hydrogels are of particular interest as regenerative scaffolds for the injured nervous system as they provide 3D bioactive interfaces that modulate cellular response to the injury environment and provide naturally degradable scaffolding for effective tissue remodeling. In this review, three unique ECM-mimetic hydrogels used in models of neural injury are reviewed: fibrin hydrogels, which rely on a naturally occurring enzymatic gelation, hyaluronic acid hydrogels, which require chemical modification prior to chemical crosslinking, and elastin-like polypeptide (ELP) hydrogels, which exhibit a temperature-sensitive gelation. The hydrogels are reviewed by summarizing their unique biological properties, their use as drug depots, and their combination with other biomaterials, such as electrospun fibers and nanoparticles. This review is the first to focus on these three ECM-mimetic hydrogels for their use in neural tissue engineering. Additionally, this is the first review to summarize the use of ELP hydrogels for nervous system applications. ECM-mimetic hydrogels have shown great promise in preclinical models of neural injury and future advancements in their design and use can likely lead to viable treatments for patients with neural injury.