Toll-like receptor 4 signaling in intracerebral hemorrhage-induced inflammation and injury

Dexmedetomidine directly binds to and inhibits Toll-like receptor 4

BACKGROUND

While a number of anesthetics has been shown potentially associated with neurotoxicity in the developing brain, dexmedetomidine, a drug that was rather recently introduced into the perioperative setting, is considered beneficial from neurological wellbeing. However, the underlying mechanism of how dexmedetomidine affects brain health remains to be determined. Based on our recent study, we hypothesized that dexmedetomidine would directly bind to and inhibit Toll-like receptor 4 (TLR4), a critical receptor largely expressed in microglia and responsible for neurological insult.

METHODS

We used TLR4 reporter assays to test if dexmedetomidine attenuates TLR4 activation. Furthermore, a direct binding of dexmedetomidine on TLR4 was tested using photoactivatable medetomidine. Lastly, the effect of dexmedetomidine on ketamine (anesthetic)-induced neurotoxicity was tested in rat pups (P7).

RESULTS

We showed that dexmedetomidine attenuated TLR4 activation using reporter assay (IC50 = 5.8 µg/mL). Photoactivatable dexmedetomidine delineated its direct binding sites on TLR4. We also showed that dexmedetomidine attenuated microglia activation both in vitro and in vivo.

DISCUSSION

We proposed a novel mechanism of dexmedetomidine-mediated neuroprotection.

Trefoil factor 1 (TFF1) reduces cerebral edema and gastric mucosal injury by regulating the EGFR/Src/FAK pathway in an intracerebral hemorrhage rat model

The destruction of the blood-brain barrier and damage to the gastrointestinal mucosa after intracerebral hemorrhage (ICH) are important reasons for its high disability and mortality rates. However, the exact etiology is not yet clear. In addition, there are currently no effective treatments for improving cerebral edema and gastric mucosal damage after ICH. Trefoil factor 1 (TFF1) is a secretory protein that plays a crucial role in maintaining the integrity and barrier function of the gastric mucosa, and it has been reported to have a protective effect on brain damage induced by various causes. This study utilized a rat model of ICH induced by type IV collagenase was utilized, and intervened with recombinant TFF1 protein from an external institute to investigate the protective mechanisms of TFF1 against brain edema and gastric mucosal damage after ICH. The results demonstrated that TFF1 alleviated the neurological function and gastric mucosal damage in the rat model of ICH induced by type IV collagenase. TFF1 may ensure the integrity of the blood-brain and gastric mucosal barriers by regulating the EGFR (epidermal growth factor receptor)/Src (non-receptor tyrosine kinase)/FAK (focal adhesion kinase) pathway. Clearly, the disruption of the blood-brain barrier and the destruction of the gastric mucosal barrier are key pathological features of ICH, and TFF1 can improve the progression of blood-brain barrier and gastric mucosal barrier disruption in ICH by regulating the EGFR/Src/FAK pathway. Therefore, TFF1 may be a potential target for the treatment of ICH.

Neuroprotection of Transcranial Cortical and Peripheral Somatosensory Electrical Stimulation by Modulating a Common Neuronal Death Pathway in Mice with Ischemic Stroke

Therapeutic electrical stimulation, such as transcranial cortical stimulation and peripheral somatosensory stimulation, is used to improve motor function in patients with stroke. We hypothesized that these stimulations exert neuroprotective effects during the subacute phase of ischemic stroke by regulating novel common signaling pathways. Male C57BL/6J mouse models of ischemic stroke were treated with high-definition (HD)-transcranial alternating current stimulation (tACS; 20 Hz, 89.1 A/mm2), HD-transcranial direct current stimulation (tDCS; intensity, 55 A/mm2; charge density, 66,000 C/m2), or electroacupuncture (EA, 2 Hz, 1 mA) in the early stages of stroke. The therapeutic effects were assessed using behavioral motor function tests. The underlying mechanisms were determined using transcriptomic and other biomedical analyses. All therapeutic electrical tools alleviated the motor dysfunction caused by ischemic stroke insults. We focused on electrically stimulating common genes involved in apoptosis and cell death using transcriptome analysis and chose 11 of the most potent targets (Trem2, S100a9, Lgals3, Tlr4, Myd88, NF-kB, STAT1, IL-6, IL-1β, TNF-α, and Iba1). Subsequent investigations revealed that electrical stimulation modulated inflammatory cytokines, including IL-1β and TNF-α, by regulating STAT1 and NF-kB activation, especially in amoeboid microglia; moreover, electrical stimulation enhanced neuronal survival by activating neurotrophic factors, including BDNF and FGF9. Therapeutic electrical stimulation applied to the transcranial cortical- or periphery-nerve level to promote functional recovery may improve neuroprotection by modulating a common neuronal death pathway and upregulating neurotrophic factors. Therefore, combining transcranial cortical and peripheral somatosensory stimulation may exert a synergistic neuroprotective effect, further enhancing the beneficial effects on motor deficits in patients with ischemic stroke.

P2Y6 Receptor Activation Aggravates NLRP3-dependent Microglial Pyroptosis via Downregulation of the PI3K/AKT Pathway in a Mouse Model of Intracerebral Hemorrhage

Pro-inflammatory signals generated after intracerebral hemorrhage (ICH) trigger a form of regulated cell death known as pyroptosis in microglia. White matter injury (WMI) refers to the condition where the white matter area of the brain suffers from mechanical, ischemic, metabolic, or inflammatory damage. Although the p2Y purinoceptor 6 (P2Y6R) plays a significant role in the control of inflammatory reactions in central nervous system diseases, its roles in the development of microglial pyroptosis and WMI following ICH remain unclear. In this study, we sought to clarify the role of P2Y6R in microglial pyroptosis and WMI by using an experimental mouse model of ICH. Type IV collagenase was injected into male C57BL/6 mice to induce ICH. Mice were then treated with MRS2578 and LY294002 to inhibit P2Y6R and phosphatidylinositol 3-kinase (PI3K), respectively. Bio-conductivity analysis was performed to examine PI3K/AKT pathway involvement in microglial pyroptosis. Quantitative Real-Time PCR, immunofluorescence staining, and western blot were conducted to examine microglial pyroptosis and WMI following ICH. A modified Garcia test, corner turning test, and forelimb placement test were used to assess neurobehavior. Hematoxylin-eosin staining (HE) was performed to detect cells damage around hematoma. Increases in the expression of P2Y6R, NLRP3, ASC, Caspase-1, and GSDMD were observed after ICH. P2Y6R was only expressed on microglia. MRS2578, a specific inhibitor of P2Y6R, attenuated short-term neurobehavioral deficits, brain edema and hematoma volume while improving both microglial pyroptosis and WMI. These changes were accompanied by decreases in pyroptosis-related proteins and pro-inflammatory cytokines both in vivo and vitro. Bioinformatic analysis revealed an association between the PI3K/AKT pathway and P2Y6R-mediated microglial pyroptosis. The effects of MRS2578 were partially reversed by treatment with LY294002, a specific PI3K inhibitor. P2Y6R inhibition alleviates microglial pyroptosis and WMI and ameliorates neurological deficits through the PI3K/AKT pathway after ICH. Consequently, targeting P2Y6R might be a promising approach for ICH treatment.

Rutaecarpine Alleviates Early Brain Injury-Induced Inflammatory Response Following Subarachnoid Hemorrhage via SIRT6/NF-[Formula: see text]B Pathway

Subarachnoid hemorrhage (SAH), a specific subtype of cerebrovascular accident, is characterized by the extravasation of blood into the interstice between the brain and its enveloping delicate tissues. This pathophysiological phenomenon can precipitate an early brain injury (EBI), which is characterized by inflammation and neuronal death. Rutaecarpine (Rut), a flavonoid compound discovered in various plants, has been shown to have protective effects against SAH-induced cerebral insult in rodent models. In our study, we used a rodent SAH model to evaluate the effect of Rut on EBI and investigated the effect of Rut on the inflammatory response and its regulation of SIRT6 expression in vitro. We found that Rut exerts a protective effect on EBI in SAH rats, which is partly due to its ability to inhibit the inflammatory response. Notably, Rut up-regulated Sirtuin 6 (SIRT6) expression, leading to an increase in H3K9 deacetylation and inhibition of nuclear factor-kappa B (NF-[Formula: see text]B) transcriptional activation, thereby mediating the inflammatory response. In addition, further data showed that SIRT6 was proven to mediate the regulation of Rut on the microglial inflammatory response. These findings highlight the importance of SIRT6 in the regulation of inflammation and suggest a potential mechanism for the protective effect of Rut on EBI. In summary, Rut may have the potential to prevent and treat SAH-induced brain injury by interacting with SIRT6. Our findings may provide a new therapeutic strategy for the treatment of SAH-induced EBI.

Chitosan revokes controlled-cortical impact generated neurological aberrations in circadian disrupted mice via TLR4-NLRP3 axis

The severity of inevitable neurological deficits and long-term psychiatric disorders in the aftermath of traumatic brain injury is influenced by pre-injury biological factors. Herein, we investigated the therapeutic effect of chitosan lactate on neurological and psychiatric aberrations inflicted by circadian disruption (CD) and controlled-cortical impact (CCI) injury in mice. Firstly, CD was developed in mice by altering sporadic day-night cycles for 2 weeks. Then, CCI surgery was performed using a stereotaxic ImpactOne device. Mice subjected to CCI displayed a significant disruption of motor coordination at 1-, 3- and 5-days post-injury (DPI) in the rotarod test. These animals showed anxiety- and depression-like behaviors in the elevated plus maze and forced-swim test at 14 and 15 DPI, respectively. Notably, mice subjected to CD + CCI exhibited severe cognitive impairment in Y-maze and novel object recognition tasks. The compromised neurological, psychiatric, and cognitive functions were mitigated in chitosan-treated mice (1 and 3 mg/mL). Immunohistochemistry and real-time PCR assay results revealed the magnified responses of prima facie biomarkers like glial-fibrillary acidic protein and ionized calcium-binding adaptor molecule 1 in the pericontusional brain region of the CD + CCI group, indicating aggravated inflammation. We also noted the depleted levels of brain-derived neurotrophic factor and augmented expression of toll-like receptor 4 (TLR4)-leucine-rich-containing family pyrin domain-containing 3 (NLRP3) signaling [apoptosis-associated-speck-like protein (ASC), caspase-1, and interleukin 1-β] in the pericontusional area of CD + CCI group. CCI-induced changes in the astrocyte-glia and aggravated immune responses were ameliorated in chitosan-treated mice. These results suggest that the neuroprotective effect of chitosan in CCI-induced brain injury may be mediated by inhibition of the TLR4-NLRP3 axis.

Pretreated MSCs with IronQ Transplantation Attenuate Microglia Neuroinflammation via the cGAS-STING Signaling Pathway

Background

Intracerebral hemorrhage (ICH), a devastating form of stroke, is characterized by elevated morbidity and mortality rates. Neuroinflammation is a common occurrence following ICH. Mesenchymal stem cells (MSCs) have exhibited potential in treating brain diseases due to their anti-inflammatory properties. However, the therapeutic efficacy of MSCs is limited by the intense inflammatory response at the transplantation site in ICH. Hence, enhancing the function of transplanted MSCs holds considerable promise as a therapeutic strategy for ICH. Notably, the iron-quercetin complex (IronQ), a metal-quercetin complex synthesized through coordination chemistry, has garnered significant attention for its biomedical applications. In our previous studies, we have observed that IronQ exerts stimulatory effects on cell growth, notably enhancing the survival and viability of peripheral blood mononuclear cells (PBMCs) and MSCs. This study aimed to evaluate the effects of pretreated MSCs with IronQ on neuroinflammation and elucidate its underlying mechanisms.

Methods

The ICH mice were induced by injecting the collagenase I solution into the right brain caudate nucleus. After 24 hours, the ICH mice were randomly divided into four subgroups, the model group (Model), quercetin group (Quercetin), MSCs group (MSCs), and pretreated MSCs with IronQ group (MSCs+IronQ). Neurological deficits were re-evaluated on day 3, and brain samples were collected for further analysis. TUNEL staining was performed to assess cell DNA damage, and the protein expression levels of inflammatory factors and the cGAS-STING signaling pathway were investigated and analyzed.

Results

Pretreated MSCs with IronQ effectively mitigate neurological deficits and reduce neuronal inflammation by modulating the microglial polarization. Moreover, the pretreated MSCs with IronQ suppress the protein expression levels of the cGAS-STING signaling pathway.

Conclusion

These findings suggest that pretreated MSCs with IronQ demonstrate a synergistic effect in alleviating neuroinflammation, thereby improving neurological function, which is achieved through the inhibition of the cGAS-STING signaling pathway.

Pink1 deficiency enhances neurological deficits and inflammatory responses after intracerebral hemorrhage in mice

Pink1 (PTEN-induced putative kinase 1) is a protein associated with maintaining mitochondrial function and integrity and has been reported to mediate neurodegeneration and neuroinflammation. While the role of Pink1 in intracerebral hemorrhage (ICH)-related neurological deficits and inflammatory responses is not deciphered. Congenic blood was transfused into the left corpus striatum to construct the ICH model in C57/BL6 wild-type (WT) and Pink1-/- mice. The relative expression of Pink1, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-2, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, Cd86, nitric oxide synthase 2 (Nos2), Cd206, arginase 1 (Arg-1), and IL-10 was detected with qRT-PCR, Western blotting, or ELISA. Mouse neurological deficit scores (mNSS) and water content were detected, and an open-field test was performed to assay anxiety-like behavior. Remarkably decreased Pink1 expression and increased MIP-2, IL-1β, MCP-1, and TNF-α expression were observed after 12 ​h, 24 ​h, 48 ​h, 72 ​h, and 7 ​d post-ICH induction in the ipsilateral injury hemispheres. Pink1 deficiency could further up-regulate mNSS scores, brain water content, MIP-2, MCP-1, IL-1β, and TNF-α in the ipsilateral injury hemispheres. On the other hand, Pink1 deficiency could decrease the number of center cross, the velocity, and the total distance traveled in open field test. Pink1 deficiency could further up-regulate the mRNA levels of pro-inflammatory (M1) molecules (Cd86, Nos2), and down-regulate the relative expression of anti-inflammatory (M2) molecules (Cd206, Arg-1, and IL-10). Pink1 deficiency deteriorates neurological deficits and inflammatory responses after ICH, which can be considered as a treatment target.

Unveiling the significance of TREM1/2 in hemorrhagic stroke: structure, function, and therapeutic implications

Stroke has long been a major threat to human health worldwide. Hemorrhagic stroke, including intracerebral hemorrhage and subarachnoid hemorrhage, exhibits a high incidence rate and a high mortality and disability rate, imposing a substantial burden on both public health and the economy and society. In recent years, the triggering receptor expressed on myeloid cells (TREM) family has garnered extensive attention in various pathological conditions, including hemorrhagic stroke. This review comprehensively summarizes the structure and function of TREM1/2, as well as their roles and potential mechanisms in hemorrhagic stroke, with the aim of providing guidance for the development of targeted therapeutic strategies in the future.

Associations Between Neuroinflammation-Related Conditions and Alzheimer's Disease: A Study of US Insurance Claims Data

Background

Early detection of Alzheimer's disease (AD) is a key component for the success of the recently approved lecanemab and aducanumab. Patients with neuroinflammation-related conditions are associated with a higher risk for developing AD.

Objective

Investigate the incidence of AD among patients with neuroinflammation-related conditions including epilepsy, hemorrhage stroke, multiple sclerosis (MS), and traumatic brain injury (TBI).

Methods

We used Optum's de-identified Clinformatics Data Mart Database (CDM). We derived covariate-matched cohorts including patients with neuroinflammation-related conditions and controls without the corresponding condition. The matched cohorts were: 1) patients with epilepsy and controls (N = 67,825 matched pairs); 2) patients with hemorrhage stroke and controls (N = 81,510 matched pairs); 3) patients with MS and controls (N = 9,853 matched pairs); and 4) patients TBI and controls (N = 104,637 matched pairs). We used the Cox model to investigate the associations between neuroinflammation-related conditions and AD.

Results

We identified that epilepsy, hemorrhage stroke, and TBI were associated with increased risks of AD in both males and females (hazard ratios [HRs]≥1.74, p < 0.001), as well as in gender- and race-conscious subpopulations (HRs≥1.64, p < 0.001). We identified that MS was associated with increased risks of AD in both males and females (HRs≥1.47, p≤0.004), while gender- and race-conscious subgroup analysis shown mixed associations.

Conclusions

Patients with epilepsy, hemorrhage stroke, MS, and/or TBI are associated with a higher risk of developing AD. More attention on cognitive status should be given to older patients with these conditions.

Prognosticators of Functional Outcome After Supratentorial Minimally Invasive Intracranial Hemorrhage Evacuation With Tubular Retractor Systems

BACKGROUND AND OBJECTIVES

Prognosticators of good functional outcome after minimally invasive surgical (MIS) intracranial hemorrhage (ICH) evacuation are poorly defined. This study aims to investigate clinical and radiographic prognosticators of poor functional outcome after MIS evacuation of ICH with tubular retractor systems.

METHODS

Single-center retrospective review of adult (age ≥18 years) patients who underwent surgical evacuation of a spontaneous supratentorial ICH evacuation using tubular retractors from 2013 to 2022 was performed. Clinical and radiographic factors, such as antiplatelet/anticoagulant use, initial NIH Stroke Scale, ICH score, premorbid modified Rankin Scale (mRS), intraventricular hemorrhage (IVH) severity according to the modified Graeb scale, and preoperative/postoperative ICH volume, were collected. The main outcome was poor functional outcome, defined as mRS score of 4-6 within 1 year postoperatively.

RESULTS

Eighty-eight patients were included. Clinical follow-up data were available for 64 (73%) patients. Of those, 43 (67%) had a poor functional outcome. On multivariate Cox regression, postoperative ICH volume ≥15 mL (hazard ratio [HR] = 2.46 [95% CI: 1.25-4.87]; P = .010) and higher modified Graeb score (HR = 1.04 [95% CI: 1-1.1]; P = .035] significantly increased the risk of poor functional outcome. Elevated postoperative ICH volume was predicted by the presence of lobar ICH (vs nonlobar, OR = 3.32 [95% CI: 1.01-11.55]; P = .043) and higher preoperative ICH volume (OR = 1.05 [1.02-1.08]; P < .001). A minimum of 60% ICH evacuation yielded an improvement in mRS 4-6 rates (HR 0.3 [95% CI: 0.1-0.8], P = .013). In patients without IVH and with a >80% ICH evacuation, the rate of mRS 4-6 was 42% compared with 67% in the whole patient sample ( P = .017).

CONCLUSION

Increased IVH volumes and residual postoperative ICH volumes are associated with poor functional outcome after MIS ICH evacuation. Postoperative ICH volume was associated with lobar ICH location as well as preoperative ICH volume. These factors may help to prognosticate patient outcomes and improve selection criteria for MIS ICH evacuation techniques.

Mesenchymal stem cells transplantation combined with IronQ attenuates ICH-induced inflammation response via Mincle/syk signaling pathway

BACKGROUND

Intracerebral hemorrhage (ICH) is a severe brain-injured disease accompanied by cerebral edema, inflammation, and subsequent neurological deficits. Mesenchymal stem cells (MSCs) transplantation has been used as a neuroprotective therapy in nervous system diseases because of its anti-inflammatory effect. Nevertheless, the biological characteristics of transplanted MSCs, including the survival rate, viability, and effectiveness, are restricted because of the severe inflammatory response after ICH. Therefore, improving the survival and viability of MSCs will provide a hopeful therapeutic efficacy for ICH. Notably, the biomedical applications of coordination chemistry-mediated metal-quercetin complex have been verified positively and studied extensively, including growth-promoting and imaging probes. Previous studies have shown that the iron-quercetin complex (IronQ) possesses extraordinary dual capabilities with a stimulating agent for cell growth and an imaging probe by magnetic resonance imaging (MRI). Therefore, we hypothesized that IronQ could improve the survival and viability of MSCs, displaying the anti-inflammation function in the treatment of ICH while also labeling MSCs for their tracking by MRI. This study aimed to explore the effects of MSCs with IronQ in regulating inflammation and further clarify their potential mechanisms.

METHODS

C57BL/6 male mice were utilized in this research. A collagenase I-induced ICH mice model was established and randomly separated into the model group (Model), quercetin gavage group (Quercetin), MSCs transplantation group (MSCs), and MSCs transplantation combined with IronQ group (MSCs + IronQ) after 24 h. Then, the neurological deficits score, brain water content (BWC), and protein expression, such as TNF-α, IL-6, NeuN, MBP, as well as GFAP, were investigated. We further measured the protein expression of Mincle and its downstream targets. Furthermore, the lipopolysaccharide (LPS)-induced BV2 cells were utilized to investigate the neuroprotection of conditioned medium of MSCs co-cultured with IronQ in vitro.

RESULTS

We found that the combined treatment of MSCs with IronQ improved the inflammation-induced neurological deficits and BWC in vivo by inhibiting the Mincle/syk signaling pathway. Conditioned medium derived from MSCs co-cultured with IronQ decreased inflammation, Mincle, and its downstream targets in the LPS-induced BV2 cell line.

CONCLUSIONS

These data suggested that the combined treatment exerts a collaborative effect in alleviating ICH-induced inflammatory response through the downregulation of the Mincle/syk signaling pathway following ICH, further improving the neurologic deficits and brain edema.

Abomasal infusion of essential fatty acids and conjugated linoleic acid during late pregnancy and early lactation affects immunohematological and oxidative stress markers in dairy cows

Oxidative stress and inflammation, as natural parts of metabolic adaptations during the transition from late gestation to early lactation, are critical indicators of dairy cows' metabolic health. This study was designed to investigate the effects of abomasal infusion of essential fatty acids (EFA), particularly α-linolenic acid, and conjugated linoleic acid (CLA) on plasma, erythrocyte, and liver markers of oxidative stress in dairy cows during the transition period. Rumen-cannulated German Holstein cows (n = 38) in their second lactation (11,101 ± 1,118 kg milk/305 d, mean ± standard deviation) were abomasally infused with one of the following treatments from d -63 antepartum until d 63 postpartum (PP): CTRL (n = 9; 76 g/d coconut oil); EFA (n = 9; 78 g/d linseed plus 4 g/d safflower oil); CLA (n = 10; isomers cis-9,trans-11 and trans-10,cis-12 CLA; 38 g/d); and EFA+CLA (n = 10; 120 g/d). Hematological parameters as well as markers of oxidative status were measured in plasma, erythrocytes, and liver before and after calving. Immunohematological parameters, including erythrocyte number, hematocrit, hemoglobin, mean corpuscular hemoglobin, leukocytes, and basophils, were affected by time, and their peak levels were observed on the day after calving. The oxidative stress markers glutathione peroxidase 1 and reactive oxygen metabolites in plasma and erythrocytes were both affected by time, exhibiting the highest levels on d 1 PP, whereas β-carotene, retinol, and tocopherol were at their lowest levels at the same time. Immunohematological parameters were only marginally affected by fatty acid treatment in a time-dependent manner. As such, lymphocyte and atypical lymphocyte counts were both significantly highest in the groups that received EFA at d 1 PP. Moreover, EFA supplementation increased the mean corpuscular volume and showed a trend for induction of mean corpuscular hemoglobin compared with the CLA group during the transition period. The PP mean thrombocyte volume was higher in the EFA than in the CLA group (except for d 28) and both EFA and CLA reduced number of thrombocytes and thrombocrit at distinct time points. Hepatic mRNA abundance of markers related to oxidative status, including glutathione peroxidase (GPX-1) and catalase (CAT), was lower (P < 0.05) in EFA-treated than non-EFA-treated cows at d 28 PP. Dairy cows at the onset of lactation were characterized by induced markers of both oxidative stress and inflammation. Supplementing EFA and CLA had minor and time-dependent effects on markers of oxidative stress in plasma, erythrocytes, and liver. A comparison of EFA supplementation with CLA or CTRL showed higher immunohematological response at d 1 PP and lower hepatic antioxidant levels by d 28 PP. Supplementation with EFA+CLA had only a minor effect on oxidative markers, which were more similar to those with the EFA treatment. Altogether, despite the time-dependent differences, the current findings show only minor effects of EFA and CLA supplementation in the prevention of early lactation-induced oxidative stress.

Dl-3-n-Butylphthalide Protects against Memory Deficits in Vascular Dementia Rats by Attenuating Pyroptosis via TLR-4/NF-κB Signaling Pathway

INTRODUCTION

Inflammation is closely associated with the pathogenesis of vascular dementia (VD). Dl-3-n-butylphthalide (NBP) is a small molecule compound extracted from the seeds of Chinese celery, which have anti-inflammatory properties in animal models of acute ischemia and patients with stroke. In this experiment, we studied the protective effects of NBP in a rat model of VD induced by permanent bilateral occlusion of the common carotid arteries and investigated the role of the TLR-4/NF-κB inflammatory signaling pathway in the pathology of VD.

METHODS

The Morris water maze test was used to evaluate cognitive deficits in the VD rats. Western blot, immunohistochemistry, and PCR analyses were used to analyze the molecular basis of the inflammatory response.

RESULTS

NBP significantly improved the learning and memory ability of VD rats. With regard to the protective mechanism, the results showed that NBP significantly downregulated the relative expression of Cleaved Cas-1/Cas-1 and Cleaved GSDMD/GSDMD. Moreover, NBP decreased the levels of the TLR-4 and NF-κB (P65) protein and phosphorylation of P65 in the hippocampus of VD rats via the TLR-4/NF-κB signaling pathway.

CONCLUSION

These findings demonstrate that NBP protects against memory deficits in permanent bilateral common carotid artery occlusion-induced VD rats by attenuating pyroptosis via the TLR-4/NF-κB signaling pathway.

Progress on siRNA-based gene therapy targeting secondary injury after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a life-threatening condition with a high mortality rate. For survivors, quality of life is determined by primary and secondary phases of injury. The prospects for injury repair and recovery after ICH are highly dependent on the extent of secondary injury. Currently, no effective treatments are available to prevent secondary injury or its long-term effects. One promising strategy that has recently garnered attention is gene therapy, in particular, small interfering RNAs (siRNA), which silence specific genes responsible for destructive effects after hemorrhage. Gene therapy as a potential treatment for ICH is being actively researched in animal studies. However, there are many barriers to the systemic delivery of siRNA-based therapy, as the use of naked siRNA has limitations. Recently, the Food and Drug Administration approved two siRNA-based therapies, and several are undergoing Phase 3 clinical trials. In this review, we describe the advancements in siRNA-based gene therapy for ICH and also summarize its advantages and disadvantages.

The hallmark and crosstalk of immune cells after intracerebral hemorrhage: Immunotherapy perspectives

Intracerebral hemorrhage (ICH) is one of the most dangerous types of strokes with a high morbidity and mortality rate. Currently, the treatment of ICH is not well developed, mainly because its mechanisms are still unclear. Inflammation is one of the main types of secondary injury after ICH and catalyzes the adverse consequences of ICH. A large number of immune cells are involved in neuroinflammation, such as microglia, astrocytes, oligodendrocytes, lymphocytes, macrophages, and neutrophils. Nevertheless, the characteristics and crosstalk of immune cells have not been fully elucidated. In this review, we endeavor to delve into the respective characteristics of immune cells and their interactions in neuroimmune inflammation, and further elucidate favorable immunotherapeutic approaches regarding ICH, and finally present an outlook.

Microglia-mediated inflammatory destruction of neuro-cardiovascular dysfunction after stroke

Stroke, a serious systemic inflammatory disease, features neurological deficits and cardiovascular dysfunction. Neuroinflammation is characterized by the activation of microglia after stroke, which disrupts the cardiovascular-related neural network and the blood-brain barrier. Neural networks activate the autonomic nervous system to regulate the cardiac and blood vessels. Increased permeability of the blood-brain barrier and the lymphatic pathways promote the transfer of the central immune components to the peripheral immune organs and the recruitment of specific immune cells or cytokines, produced by the peripheral immune system, and thus modulate microglia in the brain. In addition, the spleen will also be stimulated by central inflammation to further mobilize the peripheral immune system. Both NK cells and Treg cells will be generated to enter the central nervous system to suppress further inflammation, while activated monocytes infiltrate the myocardium and cause cardiovascular dysfunction. In this review, we will focus on microglia-mediated inflammation in neural networks that result in cardiovascular dysfunction. Furthermore, we will discuss neuroimmune regulation in the central-peripheral crosstalk, in which the spleen is a vital part. Hopefully, this will benefit in anchoring another therapeutic target for neuro-cardiovascular dysfunction.

Targeting autophagy process in center nervous trauma

The central nervous system (CNS) is the primary regulator of physiological activity, and when CNS is compromised, its physical functions are affected. Spinal cord injury (SCI) and traumatic brain injury (TBI) are common trauma in CNS that are difficult to recover from, with a higher global disability and mortality rate. Autophagy is familiar to almost all researchers due to its role in regulating the degradation and recycling of cellular defective or incorrect proteins and toxic components, maintaining body balance and regulating cell health and function. Emerging evidence suggests it has a broad and long-lasting impact on pathophysiological process such as oxidative stress, inflammation, apoptosis, and angiogenesis, involving the alteration of autophagy marker expression and function recovery. Changes in autophagy level are considered a potential therapeutic strategy and have shown promising results in preclinical studies for neuroprotection following traumatic brain injury. However, the relationship between upward or downward autophagy and functional recovery following SCI or TBI is debatable. This article reviews the regulation and role of autophagy in repairing CNS trauma and the intervention effects of autophagy-targeted therapeutic agents to find more and better treatment options for SCI and TBI patients.

Neutrophil extracellular traps: A novel target for the treatment of stroke

Stroke is a threatening cerebrovascular disease caused by thrombus with high morbidity and mortality rates. Neutrophils are the first to be recruited in the brain after stroke, which aggravate brain injury through multiple mechanisms. Neutrophil extracellular traps (NETs), as a novel regulatory mechanism of neutrophils, can trap bacteria and secret antimicrobial molecules, thereby degrading pathogenic factors and killing bacteria. However, NETs also exacerbate certain non-infectious diseases by activating autoimmune or inflammatory responses. NETs have been found to play important roles in the pathological process of stroke in recent years. In this review, the mechanisms of NETs formation, the physiological roles of NETs, and the dynamic changes of NETs after stroke are summarized. NETs participate in stroke through various mechanisms. NETs promote the coagulation cascade and interact with platelets to induce thrombosis. tPA induces the degranulation of neutrophils to form NETs, leading to hemorrhagic transformation and thrombolytic resistance. NETs aggravate stroke by mediating inflammation, atherosclerosis and vascular injury. In addition, the regulation of NETs in stroke, the potential of NETs as biomarker and the treatment of stroke targeting NETs are discussed. The increasing evidences suggest that NETs may be a potential target for stroke treatment. Inhibition of NETs formation or promotion of NETs degradation plays protective effects in stroke. However, how to avoid the adverse effects of NETs-targeted therapy deserves further study. In summary, this review provides a reference for the pathogenesis, drug targets, biomarkers and drug development of NETs in stroke.

Secondary White Matter Injury Mediated by Neuroinflammation after Intracerebral Hemorrhage and Promising Therapeutic Strategies of Targeting the NLRP3 Inflammasome

Intracerebral hemorrhage (ICH) is a neurological disease with high mortality and disability. Recent studies showed that white matter injury (WMI) plays an important role in motor dysfunction after ICH. WMI includes WMI proximal to the lesion and WMI distal to the lesion, such as corticospinal tract injury located at the cervical enlargement of the spinal cord after ICH. Previous studies have tended to focus only on gray matter (GM) injury after ICH, and fewer studies have paid attention to WMI, which may be one of the reasons for the poor outcome of previous drug treatments. Microglia and astrocyte-mediated neuroinflammation are significant mechanisms responsible for secondary WMI following ICH. The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome activation, has been shown to exacerbate neuroinflammation and brain injury after ICH. Moreover, NLRP3 inflammasome is activated in microglia and astrocytes and exerts a vital role in microglia and astrocytes-mediated neuroinflammation. We speculate that NLRP3 inflammasome activation is closely related to the polarization of microglia and astrocytes and that NLRP3 inflammasome activation may exacerbate WMI by polarizing microglia and astrocytes to the pro-inflammatory phenotype after ICH, while NLRP3 inflammasome inhibition may attenuate WMI by polarizing microglia and astrocytes to the anti-inflammatory phenotype following ICH. Therefore, NLRP3 inflammasome may act as leveraged regulatory fulcrums for microglia and astrocytes polarization to modulate WMI and WM repair after ICH. This review summarized the possible mechanisms by which neuroinflammation mediated by NLRP3 inflammasome exacerbates secondary WMI after ICH and discussed the potential therapeutic targets.

Paeoniflorin Inhibits LPS-Induced Activation of Splenic CD4+ T Lymphocytes and Relieves Pathological Symptoms in MRL/lpr Mice by Suppressing IRAK1 Signaling

Interleukin-1receptor-associated kinase 1 (IRAK1) plays a critical role in systemic lupus erythematosus (SLE). It was reported that SLE was associated with an inflammatory response mediated by defective immune tolerance, including overproduction of autoantibodies, chronic inflammation, and organ damage. Previous reports stated paeoniflorin (PF) had an immunosuppressive effect. The purpose of this study was to determine the anti-inflammatory effect of PF in SLE and its underlying mechanisms. Followed by induced with lipopolysaccharide (LPS), the splenocytes and the isolated CD4+ T lymphocytes of MRL/lpr mice were divided into three groups: control group, LPS group, and LPS + PF group, respectively. MRL/MP mice were used as the control group (treated with distilled water). The MRL/lpr mice were randomly divided into three groups: the model group (treated with distilled water), the prednisone group, and the PF group. The MRL/lpr mice were treated with prednisone acetate (5 mg/kg) and PF (25, 50, and 75 mg/kg) for eight weeks. Subsequently, ELISA, qRT-PCR, western blotting, HE, and Masson staining were performed to detect various indicators. The results of Cell Counting Kit-8 (CCK-8) showed that 10 μg/mL of LPS had the optimum effect on cell viability, and 50 μmol/L of PF had no obvious cytotoxicity to LPS-treated cells. PF reduced the expression level of IRAK1-nuclearfactor-κB (NF-κB) and its downstream inflammatory cytokines in the splenocytes and CD4+ T lymphocytes of MRL/lpr mice stimulated by LPS, especially in the latter. The serum antibody contents in the PF group mice were reduced, and the kidney damage was also alleviated accordingly. Moreover, the IRAK1/inhibitor of the nuclear factor-κB kinase (IKK)/NF-κB inhibitor (IκB)/NF-κB pathways was found to be involved in the anti-inflammation effect of PF in the kidney and spleen. In conclusion, it is thought that PF may have the potential to be used as a therapeutic agent to reduce the inflammatory activity of SLE. Inhibition of the IRAK1-NF-κB pathway may help formulate novel therapeutic tactics for SLE.

Neuroinflammation of microglia polarization in intracerebral hemorrhage and its potential targets for intervention

Microglia are the resident immune cells of the central nervous system (CNS) and play a key role in neurological diseases, including intracerebral hemorrhage (ICH). Microglia are activated to acquire either pro-inflammatory or anti-inflammatory phenotypes. After the onset of ICH, pro-inflammatory mediators produced by microglia at the early stages serve as a crucial character in neuroinflammation. Conversely, switching the microglial shift to an anti-inflammatory phenotype could alleviate inflammatory response and incite recovery. This review will elucidate the dynamic profiles of microglia phenotypes and their available shift following ICH. This study can facilitate an understanding of the self-regulatory functions of the immune system involving the shift of microglia phenotypes in ICH. Moreover, suggestions for future preclinical and clinical research and potential intervention strategies are discussed.

Activation of Nrf2 to Optimise Immune Responses to Intracerebral Haemorrhage

Haemorrhage into the brain parenchyma can be devastating. This manifests as spontaneous intracerebral haemorrhage (ICH) after head trauma, and in the context of vascular dementia. Randomised controlled trials have not reliably shown that haemostatic treatments aimed at limiting ICH haematoma expansion and surgical approaches to reducing haematoma volume are effective. Consequently, treatments to modulate the pathophysiological responses to ICH, which may cause secondary brain injury, are appealing. Following ICH, microglia and monocyte derived cells are recruited to the peri-haematomal environment where they phagocytose haematoma breakdown products and secrete inflammatory cytokines, which may trigger both protective and harmful responses. The transcription factor Nrf2, is activated by oxidative stress, is highly expressed by central nervous system microglia and macroglia. When active, Nrf2 induces a transcriptional programme characterised by increased expression of antioxidant, haem and heavy metal detoxification and proteostasis genes, as well as suppression of proinflammatory factors. Therefore, Nrf2 activation may facilitate adaptive-protective immune cell responses to ICH by boosting resistance to oxidative stress and heavy metal toxicity, whilst limiting harmful inflammatory signalling, which can contribute to further blood brain barrier dysfunction and cerebral oedema. In this review, we consider the responses of immune cells to ICH and how these might be modulated by Nrf2 activation. Finally, we propose potential therapeutic strategies to harness Nrf2 to improve the outcomes of patients with ICH.

The neuroprotective effect of dexmedetomidine and its mechanism

Dexmedetomidine (DEX) is a highly selective α2 receptor agonist that is routinely used in the clinic for sedation and anesthesia. Recently, an increasing number of studies have shown that DEX has a protective effect against brain injury caused by traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), cerebral ischemia and ischemia–reperfusion (I/R), suggesting its potential as a neuroprotective agent. Here, we summarized the neuroprotective effects of DEX in several models of neurological damage and examined its mechanism based on the current literature. Ultimately, we found that the neuroprotective effect of DEX mainly involved inhibition of inflammatory reactions, reduction of apoptosis and autophagy, and protection of the blood–brain barrier and enhancement of stable cell structures in five way. Therefore, DEX can provide a crucial advantage in neurological recovery for patients with brain injury. The purpose of this study was to further clarify the neuroprotective mechanisms of DEX therefore suggesting its potential in the clinical management of the neurological injuries.

The Analysis of SNPs' Function in miR-21 and miR146a/b in Multiple Sclerosis and Active Lesions: An In Silico Study

Multiple sclerosis (MS) is a central nervous disorder caused by several factors. Studies have recently shown that non-coding RNA such as miRNA could participate in MS initiation, progression, and active lesion. This study aims to theoretically analyze the potential impact of single-nucleotide polymorphisms (SNPs) on mir-21 and mir-146a/b, which has been previously demonstrated as MS microRNA signature. To fulfill this purpose, the SNPs were investigated for functionality through several online tools, including miRNA-SNP, SNP2-TFBS, RBP-Var, and RNAfold. Furthermore, SNPs of miR-21 and miR-146a/b that exist in pre-miRNA, mature miRNA, and promoter area were extracted; moreover, miRNA and RNA-binding protein interactions were analyzed. This article presented a list of validated SNPs that could affect the expression or function of miR-21 and miR-146a/b for the future practical study of MS and active lesions.

Mesenchymal Stem Cell Application and Its Therapeutic Mechanisms in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH), a common lethal subtype of stroke accounting for nearly 10–15% of the total stroke disease and affecting two million people worldwide, has a high mortality and disability rate and, thus, a major socioeconomic burden. However, there is no effective treatment available currently. The role of mesenchymal stem cells (MSCs) in regenerative medicine is well known owing to the simplicity of acquisition from various sources, low immunogenicity, adaptation to the autogenic and allogeneic systems, immunomodulation, self-recovery by secreting extracellular vesicles (EVs), regenerative repair, and antioxidative stress. MSC therapy provides an increasingly attractive therapeutic approach for ICH. Recently, the functions of MSCs such as neuroprotection, anti-inflammation, and improvement in synaptic plasticity have been widely researched in human and rodent models of ICH. MSC transplantation has been proven to improve ICH-induced injury, including the damage of nerve cells and oligodendrocytes, the activation of microglia and astrocytes, and the destruction of blood vessels. The improvement and recovery of neurological functions in rodent ICH models were demonstrated via the mechanisms such as neurogenesis, angiogenesis, anti-inflammation, anti-apoptosis, and synaptic plasticity. Here, we discuss the pathological mechanisms following ICH and the therapeutic mechanisms of MSC-based therapy to unravel new cues for future therapeutic strategies. Furthermore, some potential strategies for enhancing the therapeutic function of MSC transplantation have also been suggested.

miR‑30e‑5p attenuates neuronal deficit and inflammation of rats with intracerebral hemorrhage by regulating TLR4

microRNAs (miRNAs or miRs) have been reported to regulate the pathology of intracerebral hemorrhage (ICH). Therefore, the present study aimed to investigate the function of miR-30e-5p in rats with ICH with specific focus on Toll-like receptor (TLR)4. In the present study, collagenase type IV was used for the establishment of the ICH model in rats, prior to which the rats were injected with miR-30e-5p mimic or miR-30e-5p mimic + pcDNA3.1-TLR4 plasmid. The expression levels of miR-30e-5p and TLR4 were then measured using reverse transcription-quantitative PCR and western blotting. The potential interaction between miR-30e-5p and TLR4 was tested using the MicroRNA Target Prediction Database and dual-luciferase reporter and RNA immunoprecipitation assay. In addition, the concentration of TNF-α, IL-6 and IL-1β was measured using ELISA. The protein expression levels of TLR4/myeloid differentiation factor 88 (MyD88)/TIR-domain-containing adapter-inducing interferon-β (TRIF) signaling-associated molecules were measured by western blotting. Following induction of ICH, miR-30e-5p expression was downregulated, while TLR4 expression was upregulated. By contrast, injection with miR-30e-5p mimic rescued neuronal function while suppressing neuronal inflammation in rats following ICH; these effects were reversed by co-overexpression of TLR4. Furthermore, overexpression of miR-30e-5p inactivated TLR4/MyD88/TRIF signaling in rats with ICH; this was also reversed by overexpression of TLR4. Taken together, these results suggested that overexpression of miR-30e-5p exerted a protective role against neuronal deficit and inflammation caused by ICH in rats by targeting TLR4 and inactivating TLR4/MyD88/TRIF signaling.

RNA sequencing analysis between ruptured and un-ruptured brain AVM

BACKGROUND

A brain arteriovenous malformation (BAVM) is a tangle of abnormal blood vessels connecting the arteries and veins in the brain and is associated with a higher risk for intracerebral hemorrhage (ICH). RNA sequencing technology has been recently used to investigate the mechanism of diseases owing to its ability to identify the gene changes on a transcriptome-wide level. This study aims to gain insights into the potential mechanism involved in BAVM rupture.

METHODS

Sixty-five BAVM nidus samples were collected, among which 28 were ruptured and 37 were un-ruptured. Then, next-generation RNA sequencing was performed on all of them to obtain differential expressed genes (DEGs) between the two groups. In addition, bioinformatics analysis was performed to evaluate the involved biological processes and pathways by GO and KEGG analysis. Finally, we performed a univariate Cox regression analysis to obtain the early rupture-prone DEGs.

RESULTS

A total of 951 genes were differentially expressed between the ruptured and un-ruptured BAVM groups, of which 740 genes were upregulated and 211 genes were downregulated in ruptured BAVMs. Then, bioinformatics analysis showed the biological processes and pathways related to the inflammatory processes and extracellular matrix organization were significantly enriched. Meanwhile, some downregulated genes are involved in cell adhesion and genes participating in response to muscle activity and the terms of nervous system development. Finally, one hundred twenty-five genes, many were involved in inflammation, were correlated with the early rupture of BAVMs.

CONCLUSIONS

The upregulated genes in the ruptured BAVM group were involved in inflammatory processes and extracellular matrix organization. Some of the downregulated genes participated in cell adhesion and myofibril assembly, indicating the role of enhanced inflammation and reduced inflammation vessel strength in BAVMs rupture.

Community-Based Rehabilitation Promotes the Functional Recovery of Patients After Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH), a severe disorder with the high death rate, high recurrence rate and high disability rate, affected the quality of human life. Community-based rehabilitation (CBR) helps disabled people at both community and family levels. However, the effect of CBR on the recovery of people after ICH remains unclear.

METHODS

Patients were treated with the CBR training program, subsequently, medication compliance test, clinical neural impairment measurements, functional comprehensive assessments, improved Barthel index score, and life qualities assessments were to performed at 3-month or 6-month intervention of CBR to evaluate the influence of CBR on the medication compliance, physical function and life quality of patients after ICH.

RESULTS

After the treatment of CBR, we observed that, the rate of medication compliance, motor function, functional comprehensive rating scale score, modified Barthel index score, and generic quality of life inventory-74 in the CBR-treated group were significantly higher than that in the control group; the neural impairment measure score in the CBR-treated group was significantly decreased in comparison to the control group.

CONCLUSION

CBR increased the medication compliance, promoted the recovery of the neurological function and improved the life qualities of ICH patients.

Zhilong Huoxue Tongyu Capsules Ameliorate Early Brain Inflammatory Injury Induced by Intracerebral Hemorrhage via Inhibition of Canonical NFкβ Signalling Pathway

Background: Intracerebral hemorrhage (ICH) is a debilitating and fatal condition with continuously rising incidence globally, without effective treatment available. Zhilong Huoxue Tongyu (ZLHXTY) capsule is a traditional Chinese medicine that is used for ICH treatment in China. However, the evidence based mechanism is not clear.

Purpose: To study the protective effects of ZLHXTY capsules against ICH pathogenesis via targetting nuclear factor kappa β (NFкβ) canonical signalling pathway.

Methods: C57BL/6 J mice ICH models using autologous blood injection were used to study the effect of ZLHXTY (1.4 g/kg P.O.) after 24 and 72 hrs of ICH induction. The neurological scoring, corner turn test and balance beam with scoring was performed to assess neurological damage. Hematoxylin/eosin and nissl staining was used for histopathological evaluation. Levels of TNFα, NFкB, iNOS, COX2, IL1, IL6 were measured using real time qPCR and western blotting. Protein levels of IKKβ and IкBα were analyzed through western blotting. Immunofluorescence for co-expression of NeuN/TNFα, NeuN/NFкB, Iba1/TNFα, and Iba1/NFкB was also performed.

Results: Treatment with ZLHXTY capsules after ICH ameliorated inflammatory brain injury after 24 and 72 h; revealed by neurological scoring, hematoxylin/eosin and nissl staining. The qPCR and western blot analyses demonstrated significant downregulation of TNFα, NFкB, iNOS, COX2, IL1β and IL6. Further, the IKKβ and IкBα revealed significant downregulation and upregulation respectively in western blot. Immunofluorescence also revealed attenuated expression of TNFα and NFкB in neurons and also low expression of Iba1.

Conclusion: ZLHXTY capsules elicit its neuroprotective effect by targetting the NFкβ canonical signalling pathway, thereby ameliorating the ICH induced brain injury.

CD47 Blockade Accelerates Blood Clearance and Alleviates Early Brain Injury After Experimental Subarachnoid Hemorrhage

Aims

Subarachnoid hemorrhage (SAH) is a devastating stroke subtype. Following SAH, erythrocyte lysis contributes to cell death and brain injuries. Blockage of the anti-phagocytic receptor Cluster of Differentiation 47 (CD47) enhances phagocyte clearance of erythrocytes, though it has not been well-studied post-SAH. The current study aims to determine whether anti-CD47 treatment can enhance blood clearance after experimental SAH.

Methods

The prechiasmatic blood injection model of SAH was used in mice. Mice were either treated with the CD47-blocking antibody or IgG as control. The effect of the anti-CD47 antibody on blood clearance and neurological function following SAH was determined. Neuroinflammation and neuronal injury were compared between the treatment and control samples on day 1 and day 7 after SAH using flow cytometry, immunofluorescence, Fluoro-Jade C, and Nissl staining, RT-PCR, and Western blot analysis.

Results

CD47-blocking antibody sped-up blood clearance after SAH, and resulted in less neuronal injury and neurological deficits than control samples. Microglia played a role in the anti-CD47 blockade. Following SAH Following SAH, CD47 antibody-treated mice had less neuroinflammation and lower levels of apoptosis compared to controls and both one and 7 days.

Conclusions

CD47 antibody treatment has a neuroprotective effect following SAH, by increasing blood clearance rate and reducing brain injury. These findings suggest CD47 antibody treatment may improve SAH patient outcomes.

Proteinase-activated receptor-1 antagonist attenuates brain injury via regulation of FGL2 and TLR4 after intracerebral hemorrhage in mice

Proteinase-activated receptor-1 (PAR1) antagonist plays a protective effect in brain injury. We investigated the potential function and mechanisms of PAR1 antagonist in ICH-induced brain injury. Results showed that PAR1 antagonist protected against neurobehavior deficits, brain edema and BBB integrity in ICH mice via activating JNK/ERK/p38 MAPK signaling pathway at 24h after ICH. In addition, ICH resulted in the increase of FGL2 and TLR4 expression over time, and phosphorylated JNK, ERK and p38 MAPK expression. Suppression of FGL2 and TLR4 alleviated brain injury and decreased the expression of p-JNK, p-ERK, p-p38 MAPK and p-IKKα at 24 h after ICH; while overexpression of them showed the opposite result. Moreover, the protective effect of PAR1 antagonist on ICH-induced brain injury was blocked by FGL2 or TLR4 overexpression, and the levels of p-JNK, p-ERK and p-p38 MAPK were inhibited. Furthermore, PAR1 antagonist combined with TLR4 antagonist markedly alleviated brain injury after ICH at 72h. Overall, PAR1 antagonist protected against short-term brain injury, and the effect of PAR1 antagonist on ICH-induced brain injury was mediated by FGL2 or TLR4.

Microglia Phenotype and Intracerebral Hemorrhage: A Balance of Yin and Yang

Intracerebral hemorrhage (ICH) features extremely high rates of morbidity and mortality, with no specific and effective therapy. And local inflammation caused by the over-activated immune cells seriously damages the recovery of neurological function after ICH. Fortunately, immune intervention to microglia has provided new methods and ideas for ICH treatment. Microglia, as the resident immune cells in the brain, play vital roles in both tissue damage and repair processes after ICH. The perihematomal activated microglia not only arouse acute inflammatory responses, oxidative stress, excitotoxicity, and cytotoxicity to cause neuron death, but also show another phenotype that inhibit inflammation, clear hematoma and promote tissue regeneration. The proportion of microglia phenotypes determines the progression of brain tissue damage or repair after ICH. Therefore, microglia may be a promising and imperative therapeutic target for ICH. In this review, we discuss the dual functions of microglia in the brain after an ICH from immunological perspective, elaborate on the activation mechanism of perihematomal microglia, and summarize related therapeutic drugs researches.

Prognostic Significance of Admission Systemic Inflammation Response Index in Patients With Spontaneous Intracerebral Hemorrhage: A Propensity Score Matching Analysis

Intracerebral hemorrhage (ICH) accounts for ~15% of all strokes and is associated with high mortality and disability rates. The systemic inflammation response index (SIRI) is a novel systemic inflammatory marker based on peripheral neutrophil, monocyte, and lymphocyte counts. This study aimed to evaluate the prognostic significance of admission SIRI in patients with spontaneous ICH and compare its predictive ability with that of the neutrophil-to-lymphocyte ratio (NLR). This retrospective study was conducted based on a prospectively collected database of patients with ICH between June 2016 and January 2019. Propensity score matching (PSM) was conducted to adjust for potential imbalances in the clinical parameters. A total of 403 patients were included in the original cohort. The optimal SIRI cut-off value was 2.76. After 1:1 PSM based on potential confounding variables, a new cohort containing 262 patients was established for further analysis. In the original cohort, SIRI served as an independent predictor of 3-month functional outcome [odds ratio (OR), 1.302; 95% CI, 1.120–1.512; p = 0.001] and 1-month mortality (OR, 1.072; 95% CI, 1.020–1.126; p = 0.006), while NLR was independently associated with only 3-month functional outcomes (OR, 1.051; 95% CI, 1.004–1.100; p = 0.031) and not 1-month mortality. The same applied to the PSM cohort. Receiver operating characteristic analyses and predictive models indicated that in most instances, SIRI was superior to NLR and their components in predicting the outcomes of patients with ICH. Our study found that SIRI is determined to be an independent predictive indicator for ICH patients in 3-month functional outcomes and 1-month mortality. The prognostic predictive ability of SIRI was stronger than that of NLR.

Potential Role of Soluble Toll-like Receptors 2 and 4 as Therapeutic Agents in Stroke and Brain Hemorrhage

Hemolysis is a physiological condition in which red blood cells (RBCs) lyse, releasing their contents into the extracellular environment. Hemolysis can be a manifestation of several diseases and conditions, such as sickle cell disease, hemorrhagic stroke, and trauma. Heme and hemoglobin are among the unique contents of RBCs that are released into the environment. Although these contents can cause oxidative stress, especially when oxidized in the extracellular environment, they can also initiate a proinflammatory response because they bind to receptors such as the Toll-like receptor (TLR) family. This review seeks to clarify the mechanism by which TLRs initiate a proinflammatory response to heme, hemoglobin, and their oxidized derivatives, as well as the possibility of using soluble TLRs (sTLRs) as therapeutic agents. Furthermore, this review explores the possibility of using sTLRs in hemorrhagic disorders in which mitigating inflammation is essential for clinical outcomes, including hemorrhagic stroke and its subtypes, intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH).

Deep Succinylproteomics of Brain Tissues from Intracerebral Hemorrhage with Inhibition of Toll-Like Receptor 4 Signaling

It is unclear how Toll-like receptor (TLR) 4 signaling affects protein succinylation in the brain after intracerebral hemorrhage (ICH). Here, we constructed a mouse ICH model to investigate the changes in ICH-associated brain protein succinylation, following a treatment with a TLR4 antagonist, TAK242, using a high-resolution mass spectrometry-based, quantitative succinyllysine proteomics approach. We characterized the prevalence of approximately 6700 succinylation events and quantified approximately 3500 sites, highlighting 139 succinyllysine site changes in 40 pathways. Further analysis showed that TAK242 treatment induced an increase of 29 succinyllysine sites on 28 succinylated proteins and a reduction of 24 succinyllysine sites on 23 succinylated proteins in the ICH brains. TAK242 treatment induced both protein hypersuccinylations and hyposuccinylations, which were mainly located in the mitochondria and cytoplasm. GO analysis showed that TAK242 treatment-induced changes in the ICH-associated succinylated proteins were mostly located in synapses, membranes and vesicles, and enriched in many cellular functions/compartments, such as metabolism, synapse, and myelin. KEGG analysis showed that TAK242-induced hyposuccinylation was mainly linked to fatty acid metabolism, including elongation and degradation. Moreover, a combined analysis of the succinylproteomic data with previously published transcriptome data revealed that most of the differentially succinylated proteins induced by TAK242 treatment were mainly distributed throughout neurons, astrocytes, and endothelial cells, and the mRNAs of seven and three succinylated proteins were highly expressed in neurons and astrocytes, respectively. In conclusion, we revealed that several TLR4 signaling pathways affect the succinylation processes and pathways in mouse ICH brains, providing new insights on the ICH pathophysiological processes. Data are available via ProteomeXchange with identifier PXD025622.

Dietary dihydroartemisinin supplementation alleviates intestinal inflammatory injury through TLR4/NOD/NF-κB signaling pathway in weaned piglets with intrauterine growth retardation

The aim of present study was to evaluate whether diets supplemented with dihydroartemisinin (DHA) could alleviate intestinal inflammatory injury in weaned piglets with intrauterine growth retardation (IUGR). Twelve normal birth weight (NBW) piglets and 12 piglets with IUGR were fed a basal diet (NBW-CON and IUCR-CON groups), and another 12 piglets with IUGR were fed the basal diet supplemented with DHA at 80 mg/kg (IUGR-DHA group) from 21 to 49 d of age. At 49 d of age, 8 piglets with similar body weight in each group were sacrificed. The jejunal and ileal samples were collected for further analysis. The results showed that IUGR impaired intestinal morphology, increased intestinal inflammatory response, raised enterocyte apoptosis and reduced enterocyte proliferation and activated transmembrane toll-like receptor 4 (TLR4)/nucleotide-binding and oligomerization domain (NOD)/nuclear factor-κB (NF-κB) signaling pathway. Dihydroartemisinin inclusion ameliorated intestinal morphology, indicated by increased villus height, villus height-to-crypt depth ratio, villus surface area and decreased villus width of piglets with IUGR (P < 0.05). Compared with NBW piglets, IUGR piglets supplemented with DHA exhibited higher apoptosis index and caspase-3 expression, and lower proliferation index and proliferating cell nuclear antigen expression in the intestine (P < 0.05). Dihydroartemisinin supplementation attenuated the intestinal inflammation of piglets with IUGR, indicated by increased concentrations of intestinal inflammatory cytokines and lipopolysaccharides (P < 0.05). In addition, DHA supplementation down-regulated the related mRNA expressions of TLR4/NOD/NF-κB signaling pathway and upregulated mRNA expressions of negative regulators of TLR4 and NOD signaling pathway in the intestine of piglets with IUGR (P < 0.05). Piglets in the IUGR-DHA group showed lower protein expressions of TLR4, phosphorylated NF-κB (pNF-κB) inhibitor α, nuclear pNF-κB, and higher protein expression of cytoplasmic pNF-κB in the intestine than those in the IUGR-CON group (P < 0.05). In conclusion, DHA supplementation could improve intestinal morphology, regulate enterocyte proliferation and apoptosis, and alleviate intestinal inflammation through TLR4/NOD/NF-κB signaling pathway in weaned piglets with IUGR.

Dysregulation of microRNA and Intracerebral Hemorrhage: Roles in Neuroinflammation

Intracerebral hemorrhage (ICH) is a major public health problem and devastating subtype of stroke with high morbidity and mortality. Notably, there is no effective treatment for ICH. Neuroinflammation, a pathological hallmark of ICH, contributes to both brain injury and repair and hence, it is regarded as a potential target for therapeutic intervention. Recent studies document that microRNAs, small non-coding RNA molecules, can regulate inflammatory brain response after ICH and are viable molecular targets to alter brain function. Therefore, there is an escalating interest in studying the role of microRNAs in the pathophysiology of ICH. Herein, we provide, for the first time, an overview of the microRNAs that play roles in ICH-induced neuroinflammation and identify the critical knowledge gap in the field, as it would help design future studies.

Cumulative Damage: Cell Death in Posthemorrhagic Hydrocephalus of Prematurity

Globally, approximately 11% of all infants are born preterm, prior to 37 weeks’ gestation. In these high-risk neonates, encephalopathy of prematurity (EoP) is a major cause of both morbidity and mortality, especially for neonates who are born very preterm (<32 weeks gestation). EoP encompasses numerous types of preterm birth-related brain abnormalities and injuries, and can culminate in a diverse array of neurodevelopmental impairments. Of note, posthemorrhagic hydrocephalus of prematurity (PHHP) can be conceptualized as a severe manifestation of EoP. PHHP impacts the immature neonatal brain at a crucial timepoint during neurodevelopment, and can result in permanent, detrimental consequences to not only cerebrospinal fluid (CSF) dynamics, but also to white and gray matter development. In this review, the relevant literature related to the diverse mechanisms of cell death in the setting of PHHP will be thoroughly discussed. Loss of the epithelial cells of the choroid plexus, ependymal cells and their motile cilia, and cellular structures within the glymphatic system are of particular interest. Greater insights into the injuries, initiating targets, and downstream signaling pathways involved in excess cell death shed light on promising areas for therapeutic intervention. This will bolster current efforts to prevent, mitigate, and reverse the consequential brain remodeling that occurs as a result of hydrocephalus and other components of EoP.

Hypoxia-inducible factor-1: Regulatory mechanisms and drug development in stroke

Stroke is an acute cerebrovascular disease caused by sudden rupture of blood vessels in the brain or blockage of blood vessels, which has now become one of the main causes of adult death. During stroke, hypoxia-inducible factor-1 (HIF-1), as an important regulator under hypoxia conditions, is involved in the pathological process of stroke by regulating multi-pathways, such as glucose metabolism, angiogenesis, erythropoiesis, cell survival. However, the roles of HIF-1 in stroke are still controversial, which are related with ischemic time and degree of ischemia. The regulatory mechanisms of HIF-1 in stroke include inflammation, autophagy, oxidative stress, apoptosis and energy metabolism. The potential drugs targeting HIF-1 have attracted more attention, such as HIF-1 inhibitors, HIF-1 stabilizers and natural products. Based on the role of HIF-1 in stroke, HIF-1 is expected to be a potential target for stroke treatment. Resolving when and what interventions for HIF-1 to take during stroke will provide novel strategies for stroke treatment.

Toll-Like Receptor Signaling Pathways: Novel Therapeutic Targets for Cerebrovascular Disorders

Toll-like receptors (TLRs), a class of pattern recognition proteins, play an integral role in the modulation of systemic inflammatory responses. Cerebrovascular diseases (CVDs) are a group of pathological conditions that temporarily or permanently affect the brain tissue mostly via the decrease of oxygen and glucose supply. TLRs have a critical role in the activation of inflammatory cascades following hypoxic-ischemic events and subsequently contribute to neuroprotective or detrimental effects of CVD-induced neuroinflammation. The TLR signaling pathway and downstream cascades trigger immune responses via the production and release of various inflammatory mediators. The present review describes the modulatory role of the TLR signaling pathway in the inflammatory responses developed following various CVDs and discusses the potential benefits of the modulation of different TLRs in the improvement of functional outcomes after brain ischemia.

When the Blood Hits Your Brain: The Neurotoxicity of Extravasated Blood

Hemorrhage in the central nervous system (CNS), including intracerebral hemorrhage (ICH), intraventricular hemorrhage (IVH), and aneurysmal subarachnoid hemorrhage (aSAH), remains highly morbid. Trials of medical management for these conditions over recent decades have been largely unsuccessful in improving outcome and reducing mortality. Beyond its role in creating mass effect, the presence of extravasated blood in patients with CNS hemorrhage is generally overlooked. Since trials of surgical intervention to remove CNS hemorrhage have been generally unsuccessful, the potent neurotoxicity of blood is generally viewed as a basic scientific curiosity rather than a clinically meaningful factor. In this review, we evaluate the direct role of blood as a neurotoxin and its subsequent clinical relevance. We first describe the molecular mechanisms of blood neurotoxicity. We then evaluate the clinical literature that directly relates to the evacuation of CNS hemorrhage. We posit that the efficacy of clot removal is a critical factor in outcome following surgical intervention. Future interventions for CNS hemorrhage should be guided by the principle that blood is exquisitely toxic to the brain.

Inhibition of hypoxia inducible factor 1 by YC-1 attenuates tissue plasminogen activator induced hemorrhagic transformation by suppressing HMGB1/TLR4/NF-κB mediated neutrophil infiltration in thromboembolic stroke rats

Hemorrhagic transformation (HT) is a frequent complication of ischemic stroke after thrombolytic therapy and seriously affects the prognosis of stroke. Due to the limited therapeutic window and hemorrhagic complications, tissue plasminogen activator (t-PA) is underutilized in acute ischemic stroke. Currently, there are no clinically effective drugs to decrease the incidence of t-PA-induced HT. Hypoxia-inducible factor 1 (HIF-1) is an important transcription factor that maintains oxygen homeostasis and mediates neuroinflammation under hypoxia. However, the effect of HIF-1 on t-PA-induced HT is not clear. The aim of this study was to investigate the role of HIF-1 in t-PA-induced HT by applying YC-1, an inhibitor of HIF-1. In the present study, we found that HIF-1 expression was significantly increased in ischemic brain tissue after delayed t-PA treatment and was mainly localized in neurons and endothelial cells. Inhibition of HIF-1 by YC-1 improved infarct volume and neurological deficits. YC-1 inhibited matrix metalloproteinase protein expression, increased tight junction protein expression, and ameliorated BBB disruption and the occurrence of HT. Furthermore, YC-1 suppressed the release of inflammatory factors, neutrophil infiltration and the activation of the HMGB1/TLR4/NF-κB signaling pathway. These results demonstrated that inhibition of HIF-1 could protect BBB integrity by suppressing HMGB1/TLR4/NF-κB-mediated neutrophil infiltration, thereby reducing the risk of t-PA-induced HT. Thus, HIF-1 may be a potential therapeutic target for t-PA-induced HT.

Role of Adaptor Protein Myeloid Differentiation 88 (MyD88) in Post-Subarachnoid Hemorrhage Inflammation: A Systematic Review

Myeloid differentiation 88 (MyD88) is a well-established inflammatory adaptor protein. It is one of the essential downstream proteins of the toll-like receptor 4 (TLR4) signaling pathway. TLRs are pattern recognition receptors that are usually activated by the damage-associated molecular pattern molecules (DAMPs). Sterile inflammation is triggered by the endogenous DAMPs released in response to global cerebral ischemia and from extravasated blood after subarachnoid hemorrhage (SAH). In this review, we highlight the importance of the neuroinflammatory role of the MyD88 in the SAH. We also explore a few possible pharmacological agents that can be used to decrease SAH-associated neuroinflammation by modulating the MyD88 dependent functions. Pharmacological agents such as flavonoids, melatonin, fluoxetine, pentoxifylline and progesterone have been investigated experimentally to reduce the SAH-associated inflammation. Inhibition of the MyD88 not only reduces the expression of pro-inflammatory cytokines, but also potentially inhibits other processes that can augment the SAH associated inflammation. Further investigations are required to translate these findings in the clinical setting.

Mechanism of White Matter Injury and Promising Therapeutic Strategies of MSCs After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is the most fatal subtype of stroke with high disability and high mortality rates, and there is no effective treatment. The predilection site of ICH is in the area of the basal ganglia and internal capsule (IC), where exist abundant white matter (WM) fiber tracts, such as the corticospinal tract (CST) in the IC. Proximal or distal white matter injury (WMI) caused by intracerebral parenchymal hemorrhage is closely associated with poor prognosis after ICH, especially motor and sensory dysfunction. The pathophysiological mechanisms involved in WMI are quite complex and still far from clear. In recent years, the neuroprotection and repairment capacity of mesenchymal stem cells (MSCs) has been widely investigated after ICH. MSCs exert many unique biological effects, including self-recovery by producing growth factors and cytokines, regenerative repair, immunomodulation, and neuroprotection against oxidative stress, providing a promising cellular therapeutic approach for the treatment of WMI. Taken together, our goal is to discuss the characteristics of WMI following ICH, including the mechanism and potential promising therapeutic targets of MSCs, aiming at providing new clues for future therapeutic strategies.

Microglia as target for anti-inflammatory approaches to prevent secondary brain injury after subarachnoid hemorrhage (SAH)

Background

Microglia-driven cerebral spreading inflammation is a key contributor to secondary brain injury after SAH. Genetic depletion or deactivation of microglia has been shown to ameliorate neuronal cell death. Therefore, clinically feasible anti-inflammatory approaches counteracting microglia accumulation or activation are interesting targets for SAH treatment. Here, we tested two different methods of interference with microglia-driven cerebral inflammation in a murine SAH model: (i) inflammatory preconditioning and (ii) pharmacological deactivation.

Methods

7T-MRI-controlled SAH was induced by endovascular perforation in four groups of C57Bl/6 mice: (i) Sham-operation, (ii) SAH naïve, (iii) SAH followed by inflammatory preconditioning (LPS intraperitoneally), and (iv) SAH followed by pharmacological microglia deactivation (colony-stimulating factor-1 receptor-antagonist PLX3397 intraperitoneally). Microglia accumulation and neuronal cell death (immuno-fluorescence), as well as activation status (RT-PCR for inflammation-associated molecules from isolated microglia) were recorded at day 4 and 14. Toll-like receptor4 (TLR4) status was analyzed using FACS.

Results

Following SAH, significant cerebral spreading inflammation occurred. Microglia accumulation and pro-inflammatory gene expression were accompanied by neuronal cell death with a maximum on day 14 after SAH. Inflammatory preconditioning as well as PLX3397-treatment resulted in significantly reduced microglia accumulation and activation as well as neuronal cell death. TLR4 surface expression in preconditioned animals was diminished as a sign for receptor activation and internalization.

Conclusions

Microglia-driven cerebral spreading inflammation following SAH contributes to secondary brain injury. Two microglia-focused treatment strategies, (i) inflammatory preconditioning with LPS and (ii) pharmacological deactivation with PLX3397, led to significant reduction of neuronal cell death. Increased internalization of inflammation-driving TLR4 after preconditioning leaves less receptor molecules on the cell surface, providing a probable explanation for significantly reduced microglia activation. Our findings support microglia-focused treatment strategies to overcome secondary brain injury after SAH. Delayed inflammation onset provides a valuable clinical window of opportunity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02085-3.

Emerging Role of Microglia-Mediated Neuroinflammation in Epilepsy after Subarachnoid Hemorrhage

Epilepsy is a common and serious complication of subarachnoid hemorrhage (SAH), giving rise to increased morbidity and mortality. It's difficult to identify patients at high risk of epilepsy and the application of anti-epileptic drugs (AEDs) following SAH is a controversial topic. Therefore, it's pressingly needed to gain a better understanding of the risk factors, underlying mechanisms and the optimization of therapeutic strategies for epilepsy after SAH. Neuroinflammation, characterized by microglial activation and the release of inflammatory cytokines, has drawn growing attention due to its influence on patients with epilepsy after SAH. In this review, we discuss the risk factors for epilepsy after SAH and emphasize the critical role of microglia. Then we discuss how various molecules arising from pathophysiological changes after SAH activate specific receptors such as TLR4, NLRP3, RAGE, P2X7R and initiate the downstream inflammatory pathways. Additionally, we focus on the significant responses implicated in epilepsy including neuronal excitotoxicity, the disruption of blood-brain barrier (BBB) and the change of immune responses. As the application of AEDs for seizure prophylaxis after SAH remains controversial, the regulation of neuroinflammation targeting the key pathological molecules could be a promising therapeutic method. While neuroinflammation appears to contribute to epilepsy after SAH, more comprehensive experiments on their relationships are needed.

The Role of Tenascin-C in Tissue Injury and Repair After Stroke

Stroke is still one of the most common causes for mortality and morbidity worldwide. Following acute stroke onset, biochemical and cellular changes induce further brain injury such as neuroinflammation, cell death, and blood-brain barrier disruption. Matricellular proteins are non-structural proteins induced by many stimuli and tissue damage including stroke induction, while its levels are generally low in a normal physiological condition in adult tissues. Currently, a matricellular protein tenascin-C (TNC) is considered to be an important inducer to promote neuroinflammatory cascades and the resultant pathology in stroke. TNC is upregulated in cerebral arteries and brain tissues including astrocytes, neurons, and brain capillary endothelial cells following subarachnoid hemorrhage (SAH). TNC may be involved in blood-brain barrier disruption, neuronal apoptosis, and cerebral vasospasm via the activation of mitogen-activated protein kinases and nuclear factor-kappa B following SAH. In addition, post-SAH TNC levels in cerebrospinal fluid predicted the development of delayed cerebral ischemia and angiographic vasospasm in clinical settings. On the other hand, TNC is reported to promote fibrosis and exert repair effects for an experimental aneurysm via macrophages-induced migration and proliferation of smooth muscle cells. The authors review TNC-induced inflammatory signal cascades and the relationships with other matricellular proteins in stroke-related pathology.

Periodontitis Deteriorates Cognitive Function and Impairs Neurons and Glia in a Mouse Model of Alzheimer's Disease

BACKGROUND

Although periodontitis is reportedly associated with increased cognitive decline in Alzheimer's disease, the mechanisms underlying this process remain unknown. Porphyromonas gingivalis lipopolysaccharide (P.g-LPS) is an endotoxin associated with periodontal disease.

OBJECTIVE

We investigated the effect of periodontitis on learning capacity and memory of amyloid-β protein precursor (AβPP)/presenilin (PS1) transgenic mice along with the mechanisms underlying these effects.

METHODS

Mice were randomly assigned to three groups, namely AβPP/PS1 (control), P.g-LPS Injection, and P.g-LPS Injection + Ligation. Mice from the P.g-LPS Injection group were injected with P.g-LPS in the periodontal tissue three times per week for 8 weeks, while mice from the P.g-LPS Injection + Ligation group were injected with P.g-LPS and subjected to ligation of the gingival sulcus of the maxillary second molar.

RESULTS

Expression of gingival proinflammatory cytokines as well as alveolar bone resorption in P.g-LPS-injected and ligatured mice was increased compared to that in control mice. Mice in the P.g-LPS Injection + Ligation group exhibited cognitive impairment and a significant reduction in the number of neurons. Glial cell activation in the experimental groups with significantly increased amyloid-β (Aβ) levels was more pronounced relative to the control group. Induction of periodontitis was concurrent with an increase in cyclooxygenase-2, inducible nitric oxide synthase, AβPP, and beta-secretase 1 expression and a decrease in A disintegrin and metalloproteinase domain-containing protein 10 expression.

CONCLUSION

These findings indicated that periodontitis exacerbated learning and memory impairment in AβPP/PS1 mice and augmented Aβ and neuroinflammatory responses. Our study provides a theoretical basis for risk prediction and early intervention of Alzheimer's disease and periodontitis.