Tumor necrosis factor-alpha neutralization reduced cerebral edema through inhibition of matrix metalloproteinase production after transient focal cerebral ischemia

Genetic Susceptibility in Endothelial Injury Syndromes after Hematopoietic Cell Transplantation and Other Cellular Therapies: Climbing a Steep Hill

Hematopoietic stem cell transplantation (HSCT) remains a cornerstone in the management of patients with hematological malignancies. Endothelial injury syndromes, such as HSCT-associated thrombotic microangiopathy (HSCT-TMA), veno-occlusive disease/sinusoidal obstruction syndrome (SOS/VOD), and capillary leak syndrome (CLS), constitute complications after HSCT. Moreover, endothelial damage is prevalent after immunotherapy with chimeric antigen receptor-T (CAR-T) and can be manifested with cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome (ICANS). Our literature review aims to investigate the genetic susceptibility in endothelial injury syndromes after HSCT and CAR-T cell therapy. Variations in complement pathway- and endothelial function-related genes have been associated with the development of HSCT-TMA. In these genes, CFHR5, CFHR1, CFHR3, CFI, ADAMTS13, CFB, C3, C4, C5, and MASP1 are included. Thus, patients with these variations might have a predisposition to complement activation, which is also exaggerated by other factors (such as acute graft-versus-host disease, infections, and calcineurin inhibitors). Few studies have examined the genetic susceptibility to SOS/VOD syndrome, and the implicated genes include CFH, methylenetetrahydrofolate reductase, and heparinase. Finally, specific mutations have been associated with the onset of CRS (PFKFB4, CX3CR1) and ICANS (PPM1D, DNMT3A, TE2, ASXL1). More research is essential in this field to achieve better outcomes for our patients.

Integrated transcriptomic and proteomic profiling reveals the key molecular signatures of brain endothelial reperfusion injury

BACKGROUND

Reperfusion therapy after ischemic stroke often causes brain microvascular injury. However, the underlying mechanisms are unclear.

METHODS

Transcriptomic and proteomic analyses were performed on human cerebral microvascular endothelial cells following oxygen-glucose deprivation (OGD) or OGD plus recovery (OGD/R) to identify molecules and signaling pathways dysregulated by reperfusion. Major findings were further validated in a mouse model of cerebral ischemia and reperfusion.

RESULTS

Transcriptomic analysis identified 390 differentially expressed genes (DEGs) between the OGD/R and OGD group. Pathway analysis indicated that these genes were mostly associated with inflammation, including the TNF signaling pathway, TGF-β signaling pathway, cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway, and NF-κB signaling pathway. Proteomic analysis identified 201 differentially expressed proteins (DEPs), which were primarily associated with extracellular matrix destruction and remodeling, impairment of endothelial transport function, and inflammatory responses. Six genes (DUSP1, JUNB, NFKBIA, NR4A1, SERPINE1, and THBS1) were upregulated by OGD/R at both the mRNA and protein levels. In mice with cerebral ischemia and reperfusion, brain TNF signaling pathway was activated by reperfusion, and inhibiting TNF-α with adalimumab significantly attenuated reperfusion-induced brain endothelial inflammation. In addition, the protein level of THBS1 was substantially upregulated upon reperfusion in brain endothelial cells and the peri-endothelial area in mice receiving cerebral ischemia.

CONCLUSION

Our study reveals the key molecular signatures of brain endothelial reperfusion injury and provides potential therapeutic targets for the treatment of brain microvascular injury after reperfusion therapy in ischemic stroke.

NRF2 activation ameliorates blood-brain barrier injury after cerebral ischemic stroke by regulating ferroptosis and inflammation

Arterial occlusion-induced ischemic stroke (IS) is a highly frequent stroke subtype. Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that modulates antioxidant genes. Its role in IS is still unelucidated. The current study focused on constructing a transient middle cerebral artery occlusion (tMCAO) model for investigating the NRF2-related mechanism underlying cerebral ischemia/reperfusion (I/R) injury. Each male C57BL/6 mouse was injected with/with no specific NRF2 activator post-tMCAO. Changes in blood-brain barrier (BBB)-associated molecule levels were analyzed using western-blotting, PCR, immunohistochemistry, and immunofluorescence analysis. NRF2 levels within cerebral I/R model decreased at 24-h post-ischemia. NRF2 activation improved brain edema, infarct volume, and neurological deficits after MCAO/R. Similarly, sulforaphane (SFN) prevented the down-regulated tight junction proteins occludin and zonula occludens 1 (ZO-1) and reduced the up-regulated aquaporin 4 (AQP4) and matrix metalloproteinase 9 (MMP9) after tMCAO. Collectively, NRF2 exerted a critical effect on preserving BBB integrity modulating ferroptosis and inflammation. Because NRF2 is related to BBB injury regulation following cerebral I/R, this provides a potential therapeutic target and throws light on the underlying mechanism for clinically treating IS.

Novel pathophysiological insights into CAR-T cell associated neurotoxicity

Chimeric antigen receptor (CAR) T cell therapy represents a scientific breakthrough in the treatment of advanced hematological malignancies. It relies on cell engineering to direct the powerful cytotoxic T-cell activity toward tumor cells. Nevertheless, these highly powerful cell therapies can trigger substantial toxicities such as cytokine release syndrome (CRS) and immune cell-associated neurological syndrome (ICANS). These potentially fatal side effects are now better understood and managed in the clinic but still require intensive patient follow-up and management. Some specific mechanisms seem associated with the development of ICANS, such as cytokine surge caused by activated CAR-T cells, off-tumor targeting of CD19, and vascular leak. Therapeutic tools are being developed aiming at obtaining better control of toxicity. In this review, we focus on the current understanding of ICANS, novel findings, and current gaps.

Researches on cognitive sequelae of burn injury: Current status and advances

Burn injury is a devastating disease with high incidence of disability and mortality. The cognitive dysfunctions, such as memory defect, are the main neurological sequelae influencing the life quality of burn-injured patients. The post-burn cognitive dysfunctions are related to the primary peripheral factors and the secondary cerebral inflammation, resulting in the destruction of blood-brain barrier (BBB), as is shown on Computed Tomography (CT) and magnetic resonance imaging examinations. As part of the neurovascular unit, BBB is vital to the nutrition and homeostasis of the central nervous system (CNS) and undergoes myriad alterations after burn injury, causing post-burn cognitive defects. The diagnosis and treatment of cognitive dysfunctions as burn injury sequelae are of great importance. In this review, we address the major manifestations and interventions of post-burn cognitive defects, as well as the mechanisms involved in memory defect, including neuroinflammation, destruction of BBB, and hormone imbalance.

Mechanisms of immune effector cell-associated neurotoxicity syndrome after CAR-T treatment

Chimeric antigen receptor T-cell (CAR-T) treatment has revolutionized the landscape of cancer therapy with significant efficacy on hematologic malignancy, especially in relapsed and refractory B cell malignancies. However, unexpected serious toxicities such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) still hamper its broad application. Clinical trials using CAR-T cells targeting specific antigens on tumor cell surface have provided valuable information about the characteristics of ICANS. With unclear mechanism of ICANS after CAR-T treatment, unremitting efforts have been devoted to further exploration. Clinical findings from patients with ICANS strongly indicated existence of overactivated peripheral immune response followed by endothelial activation-induced blood-brain barrier (BBB) dysfunction, which triggers subsequent central nervous system (CNS) inflammation and neurotoxicity. Several animal models have been built but failed to fully replicate the whole spectrum of ICANS in human. Hopefully, novel and powerful technologies like single-cell analysis may help decipher the precise cellular response within CNS from a different perspective when ICANS happens. Moreover, multidisciplinary cooperation among the subjects of immunology, hematology, and neurology will facilitate better understanding about the complex immune interaction between the peripheral, protective barriers, and CNS in ICANS. This review elaborates recent findings about ICANS after CAR-T treatment from bed to bench, and discusses the potential cellular and molecular mechanisms that may promote effective management in the future. This article is categorized under: Cancer > Biomedical Engineering Immune System Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology.

Evolution of Blood-Brain Barrier Permeability in Subacute Ischemic Stroke and Associations With Serum Biomarkers and Functional Outcome

Background and Purpose: In the setting of acute ischemic stroke, increased blood-brain barrier permeability (BBBP) as a sign of injury is believed to be associated with increased risk of poor outcome. Pre-clinical studies show that selected serum biomarkers including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNFα), matrix metallopeptidases (MMP), and vascular endothelial growth factors (VEGFs) may play a role in BBBP post-stroke. In the subacute phase of stroke, increased BBBP may also be caused by regenerative mechanisms such as vascular remodeling and therefore may improve functional recovery. Our aim was to investigate the evolution of BBBP in ischemic stroke using contrast-enhanced (CE) magnetic resonance imaging (MRI) and to analyze potential associations with blood-derived biomarkers as well as functional recovery in subacute ischemic stroke patients.

Methods: This is an exploratory analysis of subacute ischemic stroke patients enrolled in the BAPTISe study nested within the randomized controlled PHYS-STROKE trial (interventions: 4 weeks of aerobic fitness training vs. relaxation). Patients with at least one CE-MRI before (v1) or after (v2) the intervention were eligible for this analysis. The prevalence of increased BBBP was visually assessed on T1-weighted MR-images based on extent of contrast-agent enhancement within the ischemic lesion. The intensity of increased BBBP was assessed semi-quantitatively by normalizing the mean voxel intensity within the region of interest (ROI) to the contralateral hemisphere (“normalized CE-ROI”). Selected serum biomarkers (high-sensitive CRP, IL-6, TNF-α, MMP-9, and VEGF) at v1 (before intervention) were analyzed as continuous and dichotomized variables defined by laboratory cut-off levels. Functional outcome was assessed at 6 months after stroke using the modified Rankin Scale (mRS).

Results: Ninety-three patients with a median baseline NIHSS of 9 [IQR 6–12] were included into the analysis. The median time to v1 MRI was 30 days [IQR 18–37], and the median lesion volume on v1 MRI was 4 ml [IQR 1.2–23.4]. Seventy patients (80%) had increased BBBP visible on v1 MRI. After the trial intervention, increased BBBP was still detectable in 52 patients (74%) on v2 MRI. The median time to v2 MRI was 56 days [IQR 46–67]. The presence of increased BBBP on v1 MRI was associated with larger lesion volumes and more severe strokes. Aerobic fitness training did not influence the increase of BBBP evaluated at v2. In linear mixed models, the time from stroke onset to MRI was inversely associated with normalized CE-ROI (coefficient −0.002, Standard Error 0.007, p < 0.01). Selected serum biomarkers were not associated with the presence or evolution of increased BBBP. Multivariable regression analysis did not identify the occurrence or evolution of increased BBBP as an independent predictor of favorable functional outcome post-stroke.

Conclusion: In patients with moderate-to-severe subacute stroke, three out of four patients demonstrated increased BBB permeability, which decreased over time. The presence of increased BBBP was associated with larger lesion volumes and more severe strokes. We could not detect an association between selected serum biomarkers of inflammation and an increased BBBP in this cohort. No clear association with favorable functional outcome was observed.

Trial registration: NCT01954797.

JLX001 ameliorates cerebral ischemia injury by modulating microglial polarization and compromising NLRP3 inflammasome activation via the NF-κB signaling pathway

Ischemic stroke is a devastating disease with high morbidity and mortality rates, and the proinflammatory microglia-mediated inflammatory response directly affects stroke outcome. Previous studies have reported that JLX001, a novel compound with a structure similar to that of cyclovirobuxine D (CVB-D), exerts antiapoptotic, anti-inflammatory and antioxidative effects on ischemia-induced brain injury. However, the role of JLX001 in microglial polarization and nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome regulation after ischemic stroke has not been fully investigated. In this study, we used the middle cerebral artery occlusion (MCAO) method to establish a focal cerebral ischemia model and found that JLX001 attenuated the brain infarct size and improved cerebral damage. Moreover, the expression levels of proinflammatory cytokines (interleukin [IL]-1β and tumor necrosis factor [TNF]-α) were significantly reduced while those of the anti-inflammatory cytokine IL-10 were increased in the JLX001-treated group. Immunofluorescence staining and flow cytometry revealed an increased number of anti-inflammatory phenotypic microglia and a reduced number of proinflammatory phenotypic microglia in JLX001-treated MCAO mice. Western blotting analysis showed that JLX001 inhibited the expression of NLRP3 and proteins related to the NLRP3 inflammasome axis in vivo. Furthermore, JLX001 reduced the number of NLRP3/Iba1 cells in ischemic penumbra tissues. Finally, mechanistic analysis revealed that JLX001 significantly inhibited the expression of proteins related to the NF-κB signaling pathway. Additionally, pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor, ameliorated cerebral ischemia-reperfusion injury by suppressing microglial polarization towards the proinflammatory phenotype and NLRP3 activation in vivo, further suggesting that these protective effects of JLX001 were mediated by inhibition of the NF-κB signaling pathway. These results suggest that JLX001 is a promising therapeutic approach for ischemic stroke.

Spata2 Knockdown Exacerbates Brain Inflammation via NF-κB/P38MAPK Signaling and NLRP3 Inflammasome Activation in Cerebral Ischemia/Reperfusion Rats

Brain inflammation induced by ischemic stroke is an important cause of secondary brain injury. The nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), and NLRP3 inflammasome signaling are believed to drive the progression of brain inflammation. Spermatogenesis-associated protein2 (SPATA2) functions as a partner protein that recruits CYLD, a negative regulator of NF-κB signaling, to signaling complexes. However, the role of SPATA2 in the central nervous system remains unclear and whether it is involved in regulating inflammatory responses remains controversial. Rats were subjected to transient middle cerebral artery occlusion followed by reperfusion (tMCAO/R) surgery. The expression and localization of SPATA2 in the brain were investigated. The lentivirus-mediated shRNA was employed to inhibit SPATA2 expression. The inflammatory responses and outcomes of Spata2 knockdown were investigated. SPATA2 was co-localized with CYLD in neurons. SPATA2 expression was reduced in tMCAO/R rats. Spata2 knockdown resulted in increased microglia, increased expression of Tnfa, Il-1β, and Il-18, decreased Garcia score, and increased infarct volume. Spata2 knockdown resulted in the activation of P38MAPK and NLRP3 inflammasome and the increased activation of NF-κB signaling. These results suggest that SPATA2 plays a protective role against brain inflammation induced by ischemia/reperfusion injury. Therefore, SPATA2 could be a potential therapeutic target for treating ischemic stroke.

Favorable Effects of Astaxanthin on Brain Damage due to Ischemia- Reperfusion Injury

BACKGROUND

Activated inflammation and oxidant stress during cerebral ischemia reperfusion injury (IRI) lead to brain damage. Astaxanthin (ASX) is a type of carotenoid with a strong antioxidant effect.

OBJECTIVE

The aim of this study was to investigate the role of ASX on brain IRI.

METHODS

A total of 42 adult male Sprague-Dawley rats were divided into 3 groups as control (n=14) group, IRI (n=14) group and IRI + ASX (n=14) group. Cerebral ischemia was instituted by occluding middle cerebral artery for 120 minutes and subsequently, reperfusion was performed for 48 hours. Oxidant parameter levels and protein degradation products were evaluated. Hippocampal and cortex cell apoptosis, neuronal cell count, neurological deficit score were evaluated.

RESULTS

In the IRI group, oxidant parameter levels and protein degradation products in the tissue were increased compared to control group. However, these values were significantly decreased in the IRI + ASX group (p<0.05). There was a significant decrease in hippocampal and cortex cell apoptosis and a significant increase in the number of neuronal cells in the IRI + ASX group compared to the IRI group alone (p<0.05). The neurological deficit score which was significantly lower in the IRI group compared to the control group was found to be significantly improved in the IRI + ASX group (p<0.05).

CONCLUSION

Astaxanthin protects the brain from oxidative damage and reduces neuronal deficits due to IRI injury.

Cytokines as therapeutic targets for cardio- and cerebrovascular diseases

Despite major advances in prevention and treatment, cardiac and cerebral atherothrombotic complications still account for substantial morbidity and mortality worldwide. In this context, inflammation is involved in the chronic process leading atherosclerotic plaque formation and its complications, as well as in the maladaptive response to acute ischemic events. For this reason, modulation of inflammation is nowadays seen as a promising therapeutic strategy to counteract the burden of cardio- and cerebrovascular disease. Being produced and recognized by both inflammatory and vascular cells, the complex network of cytokines holds key functions in the crosstalk of these two systems and orchestrates the progression of atherothrombosis. By binding to membrane receptors, these soluble mediators trigger specific intracellular signaling pathways eventually leading to the activation of transcription factors and a deep modulation of cell function. Both stimulatory and inhibitory cytokines have been described and progressively reported as markers of disease or interesting therapeutic targets in the cardiovascular field. Nevertheless, cytokine inhibition is burdened by harmful side effects that will most likely prevent its chronic use in favor of acute administrations in well-selected subjects at high risk. Here, we summarize the current state of knowledge regarding the modulatory role of cytokines on atherosclerosis, myocardial infarction, and stroke. Then, we discuss evidence from clinical trials specifically targeting cytokines and the potential implication of these advances into daily clinical practice.

Continuous Glibenclamide Prevents Hemorrhagic Transformation in a Rodent Model of Severe Ischemia-Reperfusion

BACKGROUND

Endovascular thrombectomy (EVT) is highly effective but may also lead to hemorrhagic transformation (HT) and edema, which may be more pronounced in severe ischemia. We sought to determine whether glibenclamide can attenuate HT and edema in a severe ischemia-reperfusion model that reflects EVT.

METHODS

Using a transient middle cerebral artery occlusion (tMCAo) rodent model of stroke, we studied two rat cohorts, one without rt-PA and a second cohort treated with rt-PA. Glibenclamide or vehicle control was administered as an intravenous bolus at reperfusion, followed by continuous subcutaneous administration with an osmotic pump.

RESULTS

Compared to vehicle control, glibenclamide improved neurological outcome (median 7, interquartile range [IQR 6-8] vs. control median 6 [IQR 0-6], p = 0.025), reduced stroke volume (323 ± 42 vs. 484 ± 60 mm3, p < 0.01), swelling volume (10 ± 4 vs. 28 ± 7%, p < 0.01) and water content (84 ± 1 vs. 85 ± 1%, p < 0.05). Glibenclamide administration also reduced HT based on ECASS criteria, densitometry (0.94 ± 0.1 vs. 1.15 ± 0.2, p < 0.01), and quantitative hemoglobin concentration (2.7 ± 1.5 vs. 6.2 ± 4.6 uL, p = 0.011). In the second cohort with rt-PA coadministration, concordant effects on HT were observed with glibenclamide.

CONCLUSIONS

Taken together, these studies demonstrated that glibenclamide reduced the amount of edema and HT after severe ischemia. This study suggests that co-administration of glibenclamide may be worth further study in severe stroke patients treated with EVT with or without IV rt-PA.

Cytokines in CAR T Cell-Associated Neurotoxicity

Chimeric antigen receptor (CAR) T cells provide new therapeutic options for patients with relapsed/refractory hematologic malignancies. However, neurotoxicity is a frequent, and potentially fatal, complication. The spectrum of manifestations ranges from delirium and language dysfunction to seizures, coma, and fatal cerebral edema. This novel syndrome has been designated immune effector cell-associated neurotoxicity syndrome (ICANS). In this review, we draw an arc from our current understanding of how systemic and potentially local cytokine release act on the CNS, toward possible preventive and therapeutic approaches. We systematically review reported correlations of secreted inflammatory mediators in the serum/plasma and cerebrospinal fluid with the risk of ICANS in patients receiving CAR T cell therapy. Possible pathophysiologic impacts on the CNS are covered in detail for the most promising candidate cytokines, including IL-1, IL-6, IL-15, and GM-CSF. To provide insight into possible final common pathways of CNS inflammation, we place ICANS into the context of other systemic inflammatory conditions that are associated with neurologic dysfunction, including sepsis-associated encephalopathy, cerebral malaria, thrombotic microangiopathy, CNS infections, and hepatic encephalopathy. We then review in detail what is known about systemic cytokine interaction with components of the neurovascular unit, including endothelial cells, pericytes, and astrocytes, and how microglia and neurons respond to systemic inflammatory challenges. Current therapeutic approaches, including corticosteroids and blockade of IL-1 and IL-6 signaling, are reviewed in the context of what is known about the role of cytokines in ICANS. Throughout, we point out gaps in knowledge and possible new approaches for the investigation of the mechanism, prevention, and treatment of ICANS.

Astaxanthin Ameliorates Ischemic-Hypoxic-Induced Neurotrophin Receptor p75 Upregulation in the Endothelial Cells of Neonatal Mouse Brains

Ischemic stroke is a leading cause of human death in present times. Two phases of pathological impact occur during an ischemic stroke, namely, ischemia and reperfusion. Both periods include individual characteristic effects on cell injury and apoptosis. Moreover, these conditions can cause severe cell defects and harm the blood-brain barrier (BBB). Also, the BBB components are the major targets in ischemia-reperfusion injury. The BBB owes its enhanced protective roles to capillary endothelial cells, which maintain BBB permeability. One of the nerve growth factor (NGF) receptors initiating cell signaling, once activated, is the p75 neurotrophin receptor (p75NTR). This receptor is involved in both the survival and apoptosis of neurons. Although many studies have attempted to explain the role of p75NTR in neurons, the mechanisms in endothelial cells remain unclear. Endothelial cells are the first cells to encounter p75NTR stimuli. In this study, we found the upregulated p75NTR expression and reductive expression of tight junction proteins after in vivo and in vitro ischemia-reperfusion injury. Moreover, astaxanthin (AXT), an antioxidant drug, was utilized and was found to reduce p75NTR expression and the number of apoptotic cells. This study verified that p75NTR plays a prominent role in endothelial cell death and provides a novel downstream target for AXT.

Heat-Shock Proteins in Neuroinflammation

The heat-shock response, one of the main pro-survival mechanisms of a living organism, has evolved as the biochemical response of cells to cope with heat stress. The most well-characterized aspect of the heat-shock response is the accumulation of a conserved set of proteins termed heat-shock proteins (HSPs). HSPs are key players in protein homeostasis acting as chaperones by aiding the folding and assembly of nascent proteins and protecting against protein aggregation. HSPs have been associated with neurological diseases in the context of their chaperone activity, as they were found to suppress the aggregation of misfolded toxic proteins. In recent times, HSPs have proven to have functions apart from the classical molecular chaperoning in that they play a role in a wider scale of neurological disorders by modulating neuronal survival, inflammation, and disease-specific signaling processes. HSPs are gaining importance based on their ability to fine-tune inflammation and act as immune modulators in various bodily fluids. However, their effect on neuroinflammation processes is not yet fully understood. In this review, we summarize the role of neuroinflammation in acute and chronic pathological conditions affecting the brain. Moreover, we seek to explore the existing literature on HSP-mediated inflammatory function within the central nervous system and compare the function of these proteins when they are localized intracellularly compared to being present in the extracellular milieu.

Post-stroke inflammation-target or tool for therapy?

Inflammation is currently considered a prime target for the development of new stroke therapies. In the acute phase of ischemic stroke, microglia are activated and then circulating immune cells invade the peri-infarct and infarct core. Resident and infiltrating cells together orchestrate the post-stroke inflammatory response, communicating with each other and the ischemic neurons, through soluble and membrane-bound signaling molecules, including cytokines. Inflammation can be both detrimental and beneficial at particular stages after a stroke. While it can contribute to expansion of the infarct, it is also responsible for infarct resolution, and influences remodeling and repair. Several pre-clinical and clinical proof-of-concept studies have suggested the effectiveness of pharmacological interventions that target inflammation post-stroke. Experimental evidence shows that targeting certain inflammatory cytokines, such as tumor necrosis factor, interleukin (IL)-1, IL-6, and IL-10, holds promise. However, as these cytokines possess non-redundant protective and immunoregulatory functions, their neutralization or augmentation carries a risk of unwanted side effects, and clinical translation is, therefore, challenging. This review summarizes the cell biology of the post-stroke inflammatory response and discusses pharmacological interventions targeting inflammation in the acute phase after a stroke that may be used alone or in combination with recanalization therapies. Development of next-generation immune therapies should ideally aim at selectively neutralizing pathogenic immune signaling, enhancing tissue preservation, promoting neurological recovery and leaving normal function intact.

Does Pretreatment with a Tumor Necrosis Factor Alpha-inhibitor Improve the Outcome After Ischemic Cerebral Infarction? A Case Report

Tumor necrosis factor-α (TNFα) plays a major role in inflammatory and vascular processes after cerebral ischemia. TNFa-Inhibitors have, on the one hand, been associated with thromboembolic events; on the other hand, they may prevent brain edema after stroke or injury. Here, we report on a 38-year old Caucasian male with a history of Crohn´s disease, treated with adalimumab, who presented without brain edema and only minor sequelae after a major ischemic stroke. This case report illustrates two interesting aspects: 1) the treatment with adalimumab could, in that case, be the etiology for the thromboembolic event; and (2) pretreatment with this TNFa-Inhibitor was the most likely reason why the formation of brain edema was suppressed.

Memory deficits and hippocampal inflammation in cerebral hypoperfusion and reperfusion in male rats: Neuroprotective role of vanillic acid

Ischemic stroke is one of the leading causes of neurological deterioration and mortality worldwide. Neuroprotective strategies are being investigated to minimize cognitive deficits after ischemic events. Here we investigated the neuroprotective potential of vanillic acid (VA) in an animal model of transient bilateral common carotid artery occlusion and reperfusion (BCCAO/R). Adult male Wistar rats (250-300 g) were randomly divided in 4 groups and submitted to either cerebral hypoperfusion-reperfusion or a sham surgery after two-weeks of pretreatment with VA and/or normal saline. To induce the animal model of hypoperfusion, bilateral common carotid arteries were occluded (2VO model) for 30 min, followed by 72 h of reperfusion. Subsequently, their cognitive performance was evaluated in a Morris water maze (MWM) test, and also hippocampi were removed for ELISA assays and TUNEL staining test. The results showed that 2VO significantly reduced the spatial memory performance in MWM. As well as, BCCAO/R increased the level of IL-6, TNF-α and TUNEL positive cells, and also decreased the contents of IL-10 in the hippocampus of vehicle- pretreated groups as compared to the sham-operated groups. Furthermore, 14 consecutive days pretreatment with VA significantly restored the spatial memory, decreased the levels of IL-6, TNF-α and TUNEL positive cells and also increased the IL-10 levels in the hippocampi of the BCCAO/R rats. VA alone did not show any change neither in the status of various cytokines nor behavioral and TUNEL staining tests over sham values. Our data confirm that VA could potentially serve as a novel, promising, and accessible neuroprotective agent against cerebrovascular insufficiency states and vascular dementia.

Therapeutical effects of vaccine from Trypanosoma cruzi amastigote surface protein 2 by simultaneous inoculation with live parasites

The aim of this study was to evaluate the efficacy of vaccine using replication-deficient human recombinant Type 5 replication-defective adenoviruses (AdHu5) carrying sequences of the amastigote surface protein 2 (ASP2) (AdASP2) in mice infected with the Trypanosoma cruzi ( T cruzi) Y strain. A total of 16 A/Sn mice female were distributed into four groups, as follows (n = 4 per group): Group 1 - Control Group (CTRL); Group 2 - Infected Group (TC): animals were infected by subcutaneous route with 150 bloodstream trypomastigotes of T cruzi Y strain; Group 3 - Immunized Group (AdASP-2): animals were immunized by intramuscular injection (im) route with 50 µL of AdSP-2 (2 × 10 ⁸ plaque forming units [pfu]/cam) at day 0; Group 4-Immunized and Infected Group (AdASP-2+TC): animals were immunized by im route with 50 µL of ASP-2 (2 × 10 ⁸  pfu/cam) and infected by T cruzi at the same day (day 0). It was observed a significant decrease of nests in the group that was immunized with AdASP-2 and infected on the same day. Tumor necrosis factor alpha (TNF-α) and inducible nitric oxide synthase (iNOS) gene expressions showed a significant increase in the AdASP-2+TC group when compared to TC group, but it was noted that Cyclooxygenase-2 (Cox-2) was increased in TC group when compared to AdASP-2+TC group. Increase of matrix metalloproteinases-2 (MMP-2) and decrease of MMP-9 immunoexpression in the AdASP-2+TC group was noticed as well. Oxidative DNA damage was present in myocardium for AdASP-2+TC group as a result of 8-hydroxydeoxyguanosine immunoexpression. Taken together, our results highlighted an increased oxidative stress, MMP-2 activity and inflammatory host response promoted by AdASP-2 against T cruzi infection.

Inflammatory molecules might become both biomarkers and therapeutic targets for stroke management

Stroke is the fifth leading cause of death and the most frequent cause of disability worldwide. Currently, stroke diagnosis is based on neuroimaging; therefore, the lack of a rapid tool to diagnose stroke is still a major concern. In addition, therapeutic approaches to combat ischemic stroke are still scarce, since the only approved therapies are directed toward restoring blood flow to the affected brain area. However, due to the reduced time window during which these therapies are effective, few patients benefit from them; therefore, alternative treatments are urgently needed to reduce stroke brain damage in order to improve patients' outcome. The inflammatory response triggered after the ischemic event plays an important role in the progression of stroke; consequently, the study of inflammatory molecules in the acute phase of stroke has attracted increasing interest in recent decades. Here, we provide an overview of the inflammatory processes occurring during ischemic stroke, as well as the potential for these inflammatory molecules to become stroke biomarkers and the possibility that these candidates will become interesting neuroprotective therapeutic targets to be blocked or stimulated in order to modulate inflammation after stroke.

Modulation of brain ACE and ACE2 may be a promising protective strategy against cerebral ischemia/reperfusion injury: an experimental trial in rats

The brain renin-angiotensin system (RAS) is considered a crucial regulator for physiological homeostasis and disease progression. We evaluated the protective effects of the angiotensin receptor blocker (ARB) telmisartan and the angiotensin-converting enzyme 2 (ACE2) activator xanthenone on experimental cerebral ischemia/reperfusion (I/R) injury. Rats were divided into a sham control, a cerebral I/R control, a standard treatment (nimodipine, 10 mg/kg/day, 15 days, p.o.), three telmisartan treatments (1, 3, and 10 mg/kg/day, 15 days, p.o.), and three xanthenone treatments (0.5, 1, and 2 mg/kg/day, 15 days, s.c.) groups. One hour after the last dose, all rats except the sham control group were exposed to 30-min cerebral ischemia followed by 24-h reperfusion. Brain ACE and ACE2 activities and the apoptotic marker caspase-3 levels were assessed. Glutathione (GSH), malondialdehyde (MDA), and nitric oxide end products (NOx) as oxidative markers and tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and IL-10 as immunological markers were assessed. Histopathological examination and immunohistochemical evaluation of glial fibrillary acidic protein (GFAP) were performed in cerebral cortex and hippocampus sections. Telmisartan and xanthenone in the higher doses restored MDA, NOx, TNF-α, IL-6, caspase-3, ACE, and GFAP back to normal levels and significantly increased GSH, IL-10, and ACE2 compared to I/R control values. Histopathologically, both agents showed mild degenerative changes and necrosis of neurons in cerebral cortex and hippocampus compared with I/R control group. Modulation of brain RAS, either through suppression of the classic ACE pathway or stimulation of its antagonist pathway ACE2, may be a promising strategy against cerebral I/R damage.

SUR1-TRPM4 channel activation and phasic secretion of MMP-9 induced by tPA in brain endothelial cells

Background

Hemorrhagic transformation is a major complication of ischemic stroke, is linked to matrix metalloproteinase-9 (MMP-9), and is exacerbated by tissue plasminogen activator (tPA). Cerebral ischemia/reperfusion is characterized by SUR1-TRPM4 (sulfonylurea receptor 1—transient receptor potential melastatin 4) channel upregulation in microvascular endothelium. In humans and rodents with cerebral ischemia/reperfusion (I/R), the SUR1 antagonist, glibenclamide, reduces hemorrhagic transformation and plasma MMP-9, but the mechanism is unknown. We hypothesized that tPA induces protease activated receptor 1 (PAR1)-mediated, Ca²⁺-dependent phasic secretion of MMP-9 from activated brain endothelium, and that SUR1-TRPM4 is required for this process.

Methods

Cerebral I/R, of 2 and 4 hours duration, respectively, was obtained using conventional middle cerebral artery occlusion. Immunolabeling was used to quantify p65 nuclear translocation. Murine and human brain endothelial cells (BEC) were studied in vitro, without and with NF-κB activation, using immunoblot, zymography and ELISA, patch clamp electrophysiology, and calcium imaging. Genetic and pharmacological manipulations were used to identify signaling pathways.

Results

Cerebral I/R caused prominent nuclear translocation of p65 in microvascular endothelium. NF-κB-activation of BEC caused de novo expression of SUR1-TRPM4 channels. In NF-κB-activated BEC: (i) tPA caused opening of SUR1-TRPM4 channels in a plasmin-, PAR1-, TRPC3- and Ca²⁺-dependent manner; (ii) tPA caused PAR1-dependent secretion of MMP-9; (iii) tonic secretion of MMP-9 by activated BEC was not influenced by SUR1 inhibition; (iv) phasic secretion of MMP-9 induced by tPA or the PAR1-agonist, TFLLR, required functional SUR1-TRPM4 channels, with inhibition of SUR1 decreasing tPA-induced MMP-9 secretion.

Conclusions

tPA induces PAR1-mediated, SUR1-TRPM4-dependent, phasic secretion of MMP-9 from activated brain endothelium.

Etanercept Prevents Histopathological Damage after Spinal Cord Injury in Rats

Background

The aim of our study is to assess the neuroprotective effects of the tumor necrosis factor alpha (TNF-α) inhibitor etanercept (ETA) on histopathological and biochemical changes following spinal cord injury (SCI).

Patients and Methods

Fifty-four male Wistar albino rats were randomly assigned into three main groups: The sham, trauma, and ETA group (n = 18 per group). Each of these groups was further divided into three subgroups (n = 6 per subgroup) based on the different tissue sampling times postinjury: 1 h, 6 h, and 24 h. Clip compression model was used for SCI. Rats in the ETA group were treated with 5 mg/kg of ETA immediately after the clip was removed. After 1, 6, and 24 h, the spinal cord was totally removed between the levels T8-T10. Sample tissue was immediately harvested and fixed for histopathological and electron microscopic examination and were analyzed for TNF-α, interleukin-1β (IL-1β), superoxide dismutase (SOD), adenosine deaminase, catalase (CAT), and malondialdehyde levels in both the tissue and serum.

Results

The serum and tissue levels of cytokines and enzymes were seen to change after SCI between hyperacute, acute, and subacute stages. Treatment with ETA selectively inhibited TNF-α, and IL-1β expression together with increased levels of antioxidative enzymes (SOD, CAT).

Conclusion

Early administration of ETA after SCI may remarkably attenuate neuronal injury by decreasing tissue and serum TNF-α and IL-1β levels, while increasing antioxidative enzymes such as SOD and CAT in subacute and acute stages, respectively.

The Anti-inflammatory Effects of Agmatine on Transient Focal Cerebral Ischemia in Diabetic Rats

BACKGROUND

In the previous study, we observed agmatine (AGM) posttreatment immediately after 30 minutes of suture occlusion of the middle cerebral artery (MCAO) reduced the infarct size and neurological deficit in diabetic rats. The aim of the present study was to investigate the anti-inflammatory effect of AGM to reduce cerebral ischemic damage in diabetic rats.

MATERIALS AND METHODS

Normoglycemic (n=20) and streptozotocin-induced diabetic rats (n=40) were subjected to 30 minutes of MCAO followed by reperfusion. Twenty diabetic rats were treated with AGM (100 mg/kg, intraperitoneal) immediately after 30 minutes of MCAO. Modified neurological examinations and rotarod exercises were performed to evaluate motor function. Western blot and immunohistochemical analysis were performed to determine the expression of inflammatory cytokines in ischemic brain tissue. Real-time polymerase chain reaction was performed to measure the mRNA expression of high-mobility group box 1, receptor for advanced glycation end products (RAGE), Toll-like receptor (TLR)2, and TLR4 RESULTS AND CONCLUSIONS:: AGM posttreatment improved the neurobehavioral activity and motor function of diabetic MCAO rats at 24 and 72 hours after reperfusion. Immunohistochemical analysis showed that AGM treatment significantly decreased the expression of inflammatory cytokines in diabetic MCAO rats at 24 and 72 hours after reperfusion (P<0.01). Western blotting and real-time polymerase chain reaction results indicated that AGM treatment significantly decreased the expression of high-mobility group box 1, RAGE, TLR2, and TLR4 in diabetic rats at 24 hours after reperfusion (P<0.05). This neuroprotective effect of AGM after MCAO was associated with modulation of the postischemic neuronal inflammation cascade.

Intra-cerebral cannabidiol infusion-induced neuroprotection is partly associated with the TNF-α/TNFR1/NF-кB pathway in transient focal cerebral ischaemia

BACKGROUND

Stroke is a neurological disease, which, in addition to high mortality, imposes many financial and mental burdens on families and the society. The main objective of this study was to investigate the effect of cannabidiol (CBD) on one of the major inflammatory pathways in cerebral ischaemia.

METHOD

Using stereotaxic surgery, the cannula was implanted into the right lateral ventricle of rats. CBD (50, 100, and 200 ng/rat; i.c.v.) was administrated for five consecutive days. After pretreatment, the rats were subjected to 60 min of right middle cerebral artery occlusion (MCAO). After 24 h, neurological deficits score, infarct volume, brain oedema, and blood-brain barrier (BBB) permeability in total, core, and penumbra areas were assessed. The expression of tumour necrosis factor alfa (TNF-α), tumour necrosis factor receptor 1 (TNFR1), and nuclear factor-kappa B (NF-кB) in the mentioned regions was also studied.

RESULTS

Administration of CBD (100 and 200 ng/rat) caused a significant reduction in infarction, brain oedema, and BBB permeability compared with the vehicle-received group. Down-regulation of TNF-α, TNFR1, and NF-кB expression was also observed by CBD.

CONCLUSION

The results achieved in this study support the idea that CBD has a cerebroprotective effect (partly through suppression of TNF-α, TNFR1, and NF-кB) on ischaemic injury.

ABBREVIATIONS

CBD, cannabidiol; ANOVA, analysis of variance; PVDF, polyvinylidene difluoride; SDS-PAGE, sodium dodecyl sulphate polyacrylamide gel electrophoresis; SEM, standard error of mean.

Correlation Between Cannabidiol-Induced Reduction of Infarct Volume and Inflammatory Factors Expression in Ischemic Stroke Model

INTRODUCTION

Recent studies demonstrated that cannabidiol had neuroprotective property. There is some evidence about effective role of cannabidiol in reduction of ischemic damages. It has been reported that infarct size is influenced by various factors after MCAO, including inflammatory factors. The aim of the present study was to evaluate the effect of cannabidiol on infarction volume and correlation of infarct size with tumor necrosis factor receptor 1 (TNFR1), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression.

METHODS

Using stereotaxic surgery, guide cannula was implanted in the right lateral ventricle. Cannabidiol (50, 100, and 200 ng/rat) was injected through ntracerebroventricular (i.c.v.) route for 5 consecutive days . Then, the rats underwent 60 minutes of right middle cerebral artery occlusion (MCAO). After 24 h reperfusion, the infarct volume in total, cortex, piriform cortex-amygdala (Pir-Amy), and striatum areas of hemisphere were assessed. The expression of inflammatory factors such as TNFR1 and NF-κB in these regions were also studied.

RESULTS

The present results indicate that in the MCAO-induced cerebral ischemia, administration of cannabidiol (100 and 200 ng/rat) causes a significant reduction in infarction volume in comparison with the vehicle group. Also, there were significant correlations between decrease of regional infarct volume and TNFR1/NF-κB expression.

CONCLUSION

The results of this study indicate that cannabidiol reduced cerebral infarction possibly through diminishing TNFR1/NF-κB-induced neurotoxicity in transient focal cerebral ischemia.

The neuroprotective effects of Tao-Ren-Cheng-Qi Tang against embolic stroke in rats

Background

Combinations of the traditional Chinese and Western medicines have been used to treat numerous diseases throughout the world, and there is a growing body of evidence showing that some of the herbs used in traditional Chinese medicine elicit significant pharmacological effects. The aim of this study was to demonstrate the neuroprotective effects of Tao-Ren-Cheng-Qi Tang (TRCQT) in combination with aspirin following middle cerebral artery occlusion (MCAO)—induced embolic stroke in rats.

Methods

A blood clot was embolized into the middle cerebral artery of rats to induce focal ischemic brain injury. After 24 h of MCAO occlusion, the rats were arbitrarily separated into five groups and subjected to different oral treatment processes with TRCQT and aspirin for 30 days before being evaluated in terms of their neurological behavior using a four-point system. The rats were sacrificed at 30 days after drug treatment and the infarct volumes were measured using a 2,3,5-triphenyltetrazolium chloride staining method. Tumor necrosis factor-α (TNF-α), c-Jun N-terminal kinases (JNK), activated caspase-3 and Bax were detected by western blot analysis. The apoptotic cells were identified by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. ROS generation was also measured by electron spin resonance spectrometry.

Results

Rats treated with TRCQT alone or in combination with aspirin showed a significantly reduced infarct volume (P < 0.001) and improved neurological outcome compared with those treated with distilled water. Rats treated with TRCQT alone (P = 0.021) or in combination with aspirin (P = 0.02) also showed significantly reduced MCAO-induced expression levels of TNF-α and pJNK (P < 0.001) in their ischemic regions. Rats treated with TRCQT alone or in combination with aspirin showed decreased apoptosis by a reduction in the number of TUNEL positive cells, which inhibited the expression of activated caspase-3 (P = 0.038) and Bax (P = 0.004; P = 0.003). TRCQT also led to a significant concentration-dependent reduction in the formation of hydroxyl radicals (P < 0.001).

Conclusions

TRCQT reduced brain infarct volume and improved neurological outcomes by reducing apoptosis, attenuating the expression of TNF-α and p-JNK, and reducing the formation of hydroxyl radicals in MCAO-induced embolic stroke of rats.

Electronic supplementary material

The online version of this article (doi:10.1186/s13020-017-0128-y) contains supplementary material, which is available to authorized users.

Barrier function in the peripheral and central nervous system-a review

The peripheral (PNS) and central nervous system (CNS) are delicate structures, highly sensitive to homeostatic changes-and crucial for basic vital functions. Thus, a selection of barriers ensures the protection of the nervous system from noxious blood-borne or surrounding stimuli. In this chapter, anatomy and functioning of the blood-nerve (BNB), the blood-brain (BBB), and the blood-spinal cord barriers (BSCB) are presented and the key tight junction (TJ) proteins described: claudin-1, claudin-3, claudin-5, claudin-11, claudin-12, claudin-19, occludin, Zona occludens-1 (ZO-1), and tricellulin are by now identified as relevant for nerval barriers. Different diseases can lead to or be accompanied by neural barrier disruption, and impairment of these barriers worsens pathology. Peripheral nerve injury and inflammatory polyneuropathy cause an increased permeability of BNB as well as BSCB, while, e.g., diseases of the CNS such as amyotrophic lateral sclerosis, multiple sclerosis, spinal cord injury, or Alzheimer's disease can progress and worsen through barrier dysfunction. Moreover, the complex role and regulation of the BBB after ischemic stroke is described. On the other side, PNS and CNS barriers hamper the delivery of drugs in diseases when the barrier is intact, e.g., in certain neurodegenerative diseases or inflammatory pain. Understanding of the barrier - regulating processes has already lead to the discovery of new molecules as drug enhancers. In summary, the knowledge of all of these mechanisms might ultimately lead to the invention of drugs to control barrier function to help ameliorating or curing neurological diseases.

LXW7 ameliorates focal cerebral ischemia injury and attenuates inflammatory responses in activated microglia in rats

Inflammation plays a pivotal role in ischemic stroke, when activated microglia release excessive pro-inflammatory mediators. The inhibition of integrin αvβ3 improves outcomes in rat focal cerebral ischemia models. However, the mechanisms by which microglia are neuroprotective remain unclear. This study evaluated whether post-ischemic treatment with another integrin αvβ3 inhibitor, the cyclic arginine-glycine-aspartic acid (RGD) peptide-cGRGDdvc (LXW7), alleviates cerebral ischemic injury. The anti-inflammatory effect of LXW7 in activated microglia within rat focal cerebral ischemia models was examined. A total of 108 Sprague-Dawley rats (250–280 g) were subjected to middle cerebral artery occlusion (MCAO). After 2 h, the rats were given an intravenous injection of LXW7 (100 μg/kg) or phosphate-buffered saline (PBS). Neurological scores, infarct volumes, brain water content (BWC) and histology alterations were determined. The expressions of pro-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β)], and Iba1-positive activated microglia, within peri-ischemic brain tissue, were assessed with ELISA, western blot and immunofluorescence staining. Infarct volumes and BWC were significantly lower in LXW7-treated rats compared to those in the MCAO + PBS (control) group. The LXW7 treatment lowered the expression of pro-inflammatory cytokines. There was a reduction of Iba1-positive activated microglia, and the TNF-α and IL-1β expressions were attenuated. However, there was no difference in the Zea Longa scores between the ischemia and LXW7 groups. The results suggest that LXW7 protected against focal cerebral ischemia and attenuated inflammation in activated microglia. LXW7 may be neuroprotective during acute MCAO-induced brain damage and microglia-related neurodegenerative diseases.

Scutellarin as a Potential Therapeutic Agent for Microglia-Mediated Neuroinflammation in Cerebral Ischemia

The cerebral ischemia is one of the most common diseases in the central nervous system that causes progressive disability or even death. In this connection, the inflammatory response mediated by the activated microglia is believed to play a central role in this pathogenesis. In the event of brain injury, activated microglia can clear the cellular debris and invading pathogens, release neurotrophic factors, etc., but in chronic activation microglia may cause neuronal death through the release of excessive inflammatory mediators. Therefore, suppression of microglial over-reaction and microglia-mediated neuroinflammation is deemed to be a therapeutic strategy of choice for cerebral ischemic damage. In the search for potential herbal extracts that are endowed with the property in suppressing the microglial activation and amelioration of neuroinflammation, attention has recently been drawn to scutellarin, a Chinese herbal extract. Here, we review the roles of activated microglia and the effects of scutellarin on activated microglia in pathological conditions especially in ischemic stroke. We have further extended the investigation with special reference to the effects of scutellarin on Notch signaling, one of the several signaling pathways known to be involved in microglial activation. Furthermore, in light of our recent experimental evidence that activated microglia can regulate astrogliosis, an interglial "cross-talk" that was amplified by scutellarin, it is suggested that in designing of a more effective therapeutic strategy for clinical management of cerebral ischemia both glial types should be considered collectively.

Inhibition of TNF-α protects in vitro brain barrier from ischaemic damage

Cerebral ischaemia, associated with neuroinflammation and oxidative stress, is known to perturb blood-brain barrier (BBB) integrity and promote brain oedema formation. Using an in vitro model of human BBB composed of brain microvascular endothelial cells and astrocytes, this study examined whether suppression of TNF-α, a potent pro-inflammatory cytokine, might attenuate ischaemia-mediated cerebral barrier damage. Radical decreases in transendothelial electrical resistance and concomitant increases in paracellular flux across co-cultures exposed to increasing periods of oxygen-glucose deprivation alone (0.5-20 h) or followed by 20 h of reperfusion (OGD ± R) confirmed the deleterious effects of ischaemic injury on cerebral barrier integrity and function which concurred with reductions in tight junction protein (claudin-5 and occludin) expressions. OGD ± R elevated TNF-α secretion, NADPH oxidase activity, O2(-) production, actin stress fibre formation, MMP-2/9 activities and apoptosis in both endothelial cells and astrocytes. Increases in MMP-2 activity were confined to its extracellular isoform and treatments with OGD+R in astrocytes where MMP-9 could not be detected at all. Co-exposure of individual cell lines or co-cultures to an anti-TNF-α antibody dramatically diminished the extent of OGD ± R-evoked oxidative stress, morphological changes, apoptosis, MMP-2/9 activities while improving the barrier function through upregulation of tight junction protein expressions. In conclusion, vitiation of the exaggerated release of TNF-α may be an important therapeutic strategy in preserving cerebral integrity and function during and following a cerebral ischaemic attack.

Neuroprotective Effects of (-)-Epigallocatechin-3-Gallate Against Focal Cerebral Ischemia/Reperfusion Injury in Rats Through Attenuation of Inflammation

Stroke is the second leading cause of death among adults worldwide. (-)-Epigallocatechin-3-gallate (EGCG) has been demonstrated to exhibit neuroprotective functions in cerebral ischemia/reperfusion injury. However, the underlying mechanisms in this process and its contribution to the protection function remain unknown. The current study examined the neuroprotective effects of EGCG after transient middle cerebral artery occlusion (tMCAO) in rats. tMCAO for 120 min was induced in male Sprague-Dawley rats treated with EGCG (50 mg/kg, i.p.) or Vehicle immediately after reperfusion. Neurological score, infarct ratio and inflammation-related molecules (assessed by 2,3,5-triphenyltetrazolium chloride, enzyme-linked immunosorbent assays, quantitative real-time PCR or western blotting) were estimated at 24 h after operation. EGCG prevented the impairment of neurological function and decreased the infarct volume, compared with the Vehicle group. The inflammation-related molecules TNF-α, IL-1β, IL-6 levels usually caused by ischemia/reperfusion were significantly ameliorated by EGCG. EGCG also inhibited the upregulation of nuclear factor-kappa B/p65 (NF-κB/p65), and induction of cyclooxygenase 2 and inducible nitric oxide synthase. The present study indicates that EGCG may be a promising therapeutic agent for cerebral ischemia/reperfusion injury through attenuation of inflammation.

The accumulation of brain water-free sodium is associated with ischemic damage independent of the blood pressure in female rats

Estrogen deficiency worsens ischemic stroke outcomes. In ovariectomized (OVX(+)) rats fed a high-salt diet (HSD), an increase in the body Na(+)/water ratio, which characterizes water-free Na(+) accumulation, was associated with detrimental vascular effects independent of the blood pressure (BP). We hypothesized that an increase in brain water-free Na(+) accumulation is associated with ischemic brain damage in OVX(+)/HSD rats. To test our hypothesis we divided female Wistar rats into 4 groups, OVX(+) and OVX(-) rats fed HSD or a normal diet (ND), and subjected them to transient cerebral ischemia. The brain Na(+)/water ratio was increased even in OVX(+)/ND rats and augmented in OVX(+)/HSD rats. The increase in the brain Na(+)/water ratio was positively correlated with expansion of the cortical infarct volume without affecting the BP. Interestingly, OVX(+) was associated with the decreased expression of ATP1α3, a subtype of the Na(+) efflux pump. HSD increased the expression of brain Na(+) influx-related molecules and the mineralocorticoid receptor (MR). The pretreatment of OVX(+)/HSD rats with the MR antagonist eplerenone reduced brain water-free Na(+) accumulation, up-regulated ATP1α3, down-regulated MR, and reduced the cortical infarct volume. Our findings show that the increase in the brain Na(+)/water ratio elicited by estrogen deficiency or HSD is associated with ischemic brain damage BP-independently, suggesting the importance of regulating the accumulation of brain water-free Na(+). The up-regulation of ATP1α3 and the down-regulation of MR may provide a promising therapeutic strategy to attenuate ischemic brain damage in postmenopausal women.

Unique brain region-dependent cytokine signatures after prolonged hypothermic cardiac arrest in rats

We previously showed that prolonged cardiac arrest (CA) produces neuronal death with microglial proliferation. Microglial proliferation, but not neuronal death, was attenuated by deeper hypothermia. Microglia are reportedly a major source of cytokines. In this study, we tested the hypotheses that (1) CA will result in highly specific regional and temporal increases in brain cytokines; and (2) these increases will be attenuated by deep hypothermia. Adult male Sprague-Dawley rats were subjected to rapid exsanguination. After 6 minutes of normothermic no-flow, different levels of hypothermia were induced by either ice-cold (IC) or room-temperature (RT) aortic flush. After 20 minutes CA, rats were resuscitated with cardiopulmonary bypass (CPB), and sacrificed at 6 or 24 hours. Rats subjected to CPB only (without CA) and shams (no CPB or CA) served as controls (n=6 per group). Cytokines were analyzed in cerebellum, cortex, hippocampus, and striatum. Immunofluorescence was used to identify cell types associated with individual cytokines. Intra-CA temperature was lower after IC versus RT flush (21°C vs. 28°C, p<0.05). At 6 hours, striatum showed a massive increase in interleukin (IL)-1α and tumor necrosis factor-alpha (TNF-α) (>100-fold higher than in hippocampus), which was attenuated by deeper hypothermia in the IC versus RT group. In contrast, IL-12 was 50-fold higher in hippocampus versus striatum. At 24 hours, cytokines decreased. In striatum, IL-1α colocalized with astrocytes while TNF-α colocalized with neurons. In hippocampus, IL-12 colocalized with hippocampal hilar neurons, the only region where neuronal degeneration was observed at 24 hours at both IC and RT groups. We report important temporo-spatial differences in the brain cytokine response to hypothermic CA, with a novel role of striatum. Astrocytes and neurons, but not microglia colocalized with individual cytokines. Hypothermia showed protective effects. These neuroinflammatory reactions precede neuronal death. New therapeutic strategies may need to target early regional neuroinflammation.

Treatment of acute cerebral ischemia using animal models: a meta-analysis

BACKGROUND

There are numerous potential treatments assessed for acute cerebral ischemia using animal models. This study aimed to assess the effect of these treatments in terms of infarct size and neurobehavioral change. This meta-analysis was conducted to determine if any of these treatments provide a superior benefit so that they might be used on humans.

METHODS

A systematic search was conducted using several electronic databases for controlled animal studies using only nonsurgical interventions for acute cerebral ischemia. A random-effects model was used.

RESULTS

After an extensive literature search, 145 studies were included in the analysis. These studies included 1408 treated animals and 1362 control animals. Treatments that had the most significant effect on neurobehavioral scales included insulin, various antagonists, including N-methyl-D-aspartate (NMDA) receptor antagonist ACEA1021, calmodulin antagonist DY-9760e, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist YM872, and antiviral agents. Treatments providing the greatest effect on infarct size included statins, sphingosine-1-phosphate agonist (fingolimod), alcohol, angiotensin, and leukotrienes. Treatments offering the greatest reduction in brain water content included various agonists, including sphingosine-1-phosphate agonist fingolimod, statins, and peroxisome proliferator-activated receptor gamma (PPAR-γ). Treatment groups with more than one study all had high heterogeneity (I2 > 80%), however, using meta-regression we determined several sources of heterogeneity including sample size of the treatment and control groups, the occlusion time, but not the year when the study was conducted.

CONCLUSIONS

Some treatments stand out when compared to others for acute cerebral ischemia in animals. Greater replication of treatment studies is required before any treatments are selected for future human trials.

Protective actions of PJ34, a poly(ADP-ribose)polymerase inhibitor, on the blood-brain barrier after traumatic brain injury in mice

Poly(ADP-ribose) polymerase (PARP) is activated by oxidative stress and plays an important role in traumatic brain injury (TBI). The objective of this study was to investigate whether PARP activation participated in the blood-brain barrier (BBB) disruption and edema formation in a mouse model of controlled cortical impact (CCI). N-(6-oxo-5,6-dihydrophenanthridin-2-yl)-N,N-dimethylacetamide (PJ34) (10 mg/kg), a selective PARP inhibitor, was administered intraperitoneally at 5 min and 8 h after experimental CCI. After 6 h and 24 h of CCI, the permeability of the cortical BBB was determined after Evans Blue administration. The water content of the brain was also measured. Treatment with PJ34 markedly attenuated the permeability of the BBB and decreased the brain edema at 6 h and 24 h after CCI. Our data showed the up-regulation of nuclear factor-κB in cytosolic fractions and nuclear fractions in the injured cortex, and these changes were reversed by PJ34. Moreover, PJ34 significantly lessened the activities of myeloperoxidase and the levels of matrix metalloproteinase-9, enhanced the levels of occludin, laminin, collagen IV and integrin β1, reduced neurological deficits, decreased the contusion volume, and attenuated the necrotic and apoptotic neuronal cell death. These data suggest the protective effects of PJ34 on BBB integrity and cell death during acute TBI.

TNFR1-JNK signaling is the shared pathway of neuroinflammation and neurovascular damage after LPS-sensitized hypoxic-ischemic injury in the immature brain

Background

Hypoxic-ischemia (HI) and inflammation are the two major pathogenic mechanisms of brain injury in very preterm infants. The neurovascular unit is the major target of HI injury in the immature brain. Systemic inflammation may worsen HI by up-regulating neuroinflammation and disrupting the blood–brain barrier (BBB). Since neurons and oligodendrocytes, microvascular endothelial cells, and microglia may closely interact with each other, there may be a common signaling pathway leading to neuroinflammation and neurovascular damage after injury in the immature brain. TNF-α is a key pro-inflammatory cytokine that acts through the TNF receptor (TNFR), and c-Jun N-terminal kinases (JNK) are important stress-responsive kinases.

Objective

To determine if TNFR1-JNK signaling is a shared pathway underlying neuroinflammation and neurovascular injury after lipopolysaccharide (LPS)-sensitized HI in the immature brain.

Methods

Postpartum (P) day-5 mice received LPS or normal saline (NS) injection before HI. Immunohistochemistry, immunoblotting and TNFR1- and TNFR2-knockout mouse pups were used to determine neuroinflammation, BBB damage, TNF-α expression, JNK activation, and cell apoptosis. The cellular distribution of p-JNK, TNFR1/TNFR2 and cleaved caspase-3 were examined using immunofluorescent staining.

Results

The LPS + HI group had significantly greater up-regulation of activated microglia, TNF-α and TNFR1 expression, and increases of BBB disruption and cleaved caspase-3 levels at 24 hours post-insult, and showed more cortical and white matter injury on P17 than the control and NS + HI groups. Cleaved caspase-3 was highly expressed in microvascular endothelial cells, neurons, and oligodendroglial precursor cells. LPS-sensitized HI also induced JNK activation and up-regulation of TNFR1 but not TNFR2 expression in the microglia, endothelial cells, neurons, and oligodendrocyte progenitors, and most of the TNFR1-positive cells co-expressed p-JNK. Etanercept (a TNF-α inhibitor) and AS601245 (a JNK inhibitor) protected against LPS-sensitized HI brain injury. The TNFR1-knockout but not TNFR2-knockout pups had significant reduction in JNK activation, attenuation of microglial activation, BBB breakdown and cleaved caspase-3 expression, and showed markedly less cortical and white matter injury than the wild-type pups after LPS-sensitized HI.

Conclusion

TNFR1-JNK signaling is the shared pathway leading to neuroinflammation and neurovascular damage after LPS-sensitized HI in the immature brain.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-014-0215-2) contains supplementary material, which is available to authorized users.

Matrix Metalloproteinase-8 is a Novel Pathogenetic Factor in Focal Cerebral Ischemia

The neutrophil collagenase matrix metalloproteinase-8 (MMP8) is a recently identified member of MMPs that have important roles in various inflammation-related disorders. Previously, we identified MMP8 as a new neuroinflammatory mediator in activated microglia by regulating TNF-α productivity. Here, we present evidence that MMP8 is a critical factor for brain damage in transient focal cerebral ischemia by modulating neuroinflammation likely microglial activation and TNF-α production. Biochemical analyses showed upregulation of MMP8 expression at mRNA and protein levels in transient middle cerebral artery occlusion/reperfusion (M/R)-challenged brains. Furthermore, double immunolabeling showed that MMP8 expression was upregulated in the activated microglia of M/R-challenged brains. Assessment of infarct volume, neurological score, and survival/death of neural cells revealed that administration of an MMP8 inhibitor (M8I) immediately after reperfusion reduced brain damage. Histological analyses showed that microglial activation and TNF-α expression in ischemic conditions was abrogated by exposure to M8I, as demonstrated in our previous study using cultured microglia. These outcomes from a pharmacological approach were reaffirmed by a genetic approach using a lentiviral system. Intracerebroventricular microinjection of MMP8-specific shRNA lentivirus reduced the extent of ischemia-induced brain damage, as assessed by infarct volume, neurological score, microglial activation, and TNF-α expression. These results suggest a novel pathogenetic role of MMP8 and implicate modulation of its activity as a tractable strategy for therapies against cerebral ischemia.

Soluble or soluble/membrane TNF-α inhibitors protect the brain from focal ischemic injury in rats

Tumor Necrosis Factor-alpha (TNF-α) is an immunomodulatory and proinflammatory cytokine implicated in neuro-inflammation and neuronal damage in response to cerebral ischemia. The present study tested the hypothesis that anti-TNF-α agents may be protective against cerebral infarction. Transient focal ischemia was artificially induced in anesthetized adult male Wistar rats (300-350 g) by middle cerebral artery occlusion (MCAO) with an intraluminal suture. TNF-α function was interfered with either a chimeric monoclonal antibody against TNF-α (infliximab-7 mg/kg) aiming to TNF-α soluble and membrane-attached form; or a chimeric fusion protein of TNF-α receptor-2 with a fragment crystallizable (Fc) region of IgG1 (etanercept-5 mg/kg) aiming for the TNF-α soluble form. Both agents were administered intraperitoneally 0 or 6 h after inducing ischemia. Infarct volume was measured by 2,3,5-triphenyltetrazolium chloride staining. Cerebral infarct volume was significantly reduced in either etanercept or infliximab-treated group compared with non-treated MCAO rats 24 h after reperfusion. These results suggest that anti-TNF-α agents may reduce focal ischemic injury in rats.

Anti-inflammatory effects of Edaravone and Scutellarin in activated microglia in experimentally induced ischemia injury in rats and in BV-2 microglia

Background

In response to cerebral ischemia, activated microglia release excessive inflammatory mediators which contribute to neuronal damage. Therefore, inhibition of microglial over-activation could be a therapeutic strategy to alleviate various microglia-mediated neuroinflammation. This study was aimed to elucidate the anti-inflammatory effects of Scutellarin and Edaravone given either singly, or in combination in activated microglia in rats subjected to middle cerebral artery occlusion (MCAO), and in lipopolysaccharide (LPS)-induced BV-2 microglia. Expression of proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and inducible nitric oxide synthase (iNOS) was assessed by immunofluorescence staining and Western blot. Reactive oxygen species (ROS) and nitric oxide (NO) levels were determined by flow cytometry and fluorescence microscopy, respectively.

Results

In vivo, both Edaravone and Scutellarin markedly reduced the infarct cerebral tissue area with the latter drug being more effective with the dosage used; furthermore, when used in combination the reduction was more substantial. Remarkably, a greater diminution in distribution of activated microglia was observed with the combined drug treatment which also attenuated the immunoexpression of TNF-α, IL-1β and iNOS to a greater extent as compared to the drugs given separately. In vitro, both drugs suppressed upregulated expression of inflammatory cytokines, iNOS, NO and ROS in LPS-induced BV-2 cells. Furthermore, Edaravone and Scutellarin in combination cumulatively diminished the expression levels of the inflammatory mediators being most pronounced for TNF-α as evidenced by Western blot.

Conclusion

The results suggest that Edaravone and Scutellarin effectively suppressed the inflammatory responses in activated microglia, with Scutellarin being more efficacious within the dosage range used. Moreover, when both drugs were used in combination, the infarct tissue area was reduced more extensively; also, microglia-mediated inflammatory mediators notably TNF-α expression was decreased cumulatively.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-014-0125-3) contains supplementary material, which is available to authorized users.

Production of MMP-9 and inflammatory cytokines by Trypanosoma cruzi-infected macrophages

Matrix metalloproteinases (MMPs) constitute a large family of Zn(2+) and Ca(2+) dependent endopeptidases implicated in tissue remodeling and chronic inflammation. MMPs also play key roles in the activation of growth factors, chemokines and cytokines produced by many cell types, including lymphocytes, granulocytes, and, in particular, activated macrophages. Their synthesis and secretion appear to be important in a number of physiological processes, including the inflammatory process. Here, we investigated the interaction between human and mouse macrophages with T. cruzi Colombian and Y strains to characterize MMP-9 and cytokine production in this system. Supernatants and total extract of T. cruzi infected human and mouse macrophages were obtained and used to assess MMP-9 profile and inflammatory cytokines. The presence of metalloproteinase activity was determined by zymography, enzyme-linked immunosorbent assay and immunoblotting assays. The effect of cytokines on MMP-9 production in human macrophages was verified by previous incubation of cytokines on these cells in culture, and analyzed by zymography. We detected an increase in MMP-9 production in the culture supernatants of T. cruzi infected human and mouse macrophages. The addition of IL-1β or TNF-α to human macrophage cultures increased MMP-9 production. In contrast, MMP-9 production was down-modulated when human macrophage cultures were treated with IFN-γ or IL-4 before infection. Human macrophages infected with T. cruzi Y or Colombian strains produced increased levels of MMP-9, which was related to the production of cytokines such as IL-1β, TNF-α and IL-6.

Pomegranate extract protects against cerebral ischemia/reperfusion injury and preserves brain DNA integrity in rats

AIM

Interruption to blood flow causes ischemia and infarction of brain tissues with consequent neuronal damage and brain dysfunction. Pomegranate extract is well tolerated, and safely consumed all over the world. Interestingly, pomegranate extract has shown remarkable antioxidant and anti-inflammatory effects in experimental models. Many investigators consider natural extracts as novel therapies for neurodegenerative disorders. Therefore, this study was carried out to investigate the protective effects of standardized pomegranate extract against cerebral ischemia/reperfusion-induced brain injury in rats.

MAIN METHODS

Adult male albino rats were randomly divided into sham-operated control group, ischemia/reperfusion (I/R) group, and two other groups that received standardized pomegranate extract at two dose levels (250, 500 mg/kg) for 15 days prior to ischemia/reperfusion (PMG250+I/R, and PMG500+I/R groups). After I/R or sham operation, all rats were sacrificed and brains were harvested for subsequent biochemical analysis.

KEY FINDINGS

Results showed reduction in brain contents of MDA (malondialdehyde), and NO (nitric oxide), in addition to enhancement of SOD (superoxide dismutase), GPX (glutathione peroxidase), and GRD (glutathione reductase) activities in rats treated with pomegranate extract prior to cerebral I/R. Moreover, pomegranate extract decreased brain levels of NF-κB p65 (nuclear factor kappa B p65), TNF-α (tumor necrosis factor-alpha), caspase-3 and increased brain levels of IL-10 (interleukin-10), and cerebral ATP (adenosine triphosphate) production. Comet assay showed less brain DNA (deoxyribonucleic acid) damage in rats protected with pomegranate extract.

SIGNIFICANCE

The present study showed, for the first time, that pre-administration of pomegranate extract to rats, can offer a significant dose-dependent neuroprotective activity against cerebral I/R brain injury and DNA damage via antioxidant, anti-inflammatory, anti-apoptotic and ATP-replenishing effects.