DKK3 attenuates JNK and AP-1 induced inflammation via Kremen-1 and DVL-1 in mice following intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is the most devastating stroke subtype, with a poor prognosis and few proven treatments. Neuroinflammation is associated with ICH-induced brain injury and unfavorable outcomes. There is growing evidence that Dickkopf (DKK) 3 plays a key role in the adaptive anti-inflammatory and neuroprotective responses following intracerebral hemorrhage. This study aimed to evaluate the protective effects of DKK3 against brain edema and neuroinflammation in a mice model of ICH.

METHODS

Male, adult CD1 mice were subjected to sham or ICH surgery using a collagenase injection model. ICH animals received either recombinant DKK3, Kremen-1 siRNA, or DVL-1 siRNA. The neurobehavioral deficits were evaluated at 24 h, 72 h, and 28 days after ICH induction. Western blot and immunofluorescence were employed to examine the expression and localization of DKK3, Kremen-1, Dishevelled-1 (DVL-1), c-JUN N-terminal kinase (JNK), Activator protein-1 (AP-1), cleaved caspase-1, NF-κB, and IL-1β in the brain.

RESULTS

The expression of endogenous DKK3 and DVL-1 was transiently decreased after ICH compared to that in the sham group. Compared to the mice of ICH, exogenous rDKK3 administration reduced the brain water content and affected the neurological functions in ICH mice. Moreover, DKK3 was colocalized with Kremen-1 in microglia. Using a Kremen-1 or DVL-1 siRNA-induced in vivo knockdown approach, we demonstrated that the effects of DKK3 against ICH were mediated, at least partly, by the Kremen-1 and DVL-1 pathways.

CONCLUSIONS

DKK3 improves the neurological outcomes, potentially by decreasing JNK/AP-1-mediated inflammation, thereby ameliorating the short- and long-term sequelae after ICH.

Acute Treatment With Gleevec Does Not Promote Early Vascular Recovery Following Intracerebral Hemorrhage in Adult Male Rats

Intracerebral hemorrhage (ICH) remains one of the most debilitating types of stroke and is characterized by a sudden bleeding from a ruptured blood vessel. ICH often results in high mortality and in survivors, permanent disability. Most studies have focused on neuroprotective strategies designed to minimize secondary consequences and prevent further pathology. Lacking is an understanding of how ICH acutely affects cerebrovascular components and their response to therapeutic interventions. We hypothesized that ICH alters cortical vessel complexity in the parenchyma adjacent to site of the initial vascular disruption and that vascular abnormalities would be mitigated by administration of the PDGFR inhibitor, Imatinib mesylate (Gleevec). Briefly, ICH was induced in male adult rats by injection of collagenase into basal ganglia, followed by Gleevec administration (60 mg/kg) 1 h after injury. Rats were then perfused using vessel painting methodology (Salehi et al., 2018b) to stain whole brain vascular networks at 1 day post-ICH. Axial and coronal wide field fluorescence microscopy was performed. Analyses for vascular features were undertaken and fractal analysis for vascular complexity. Data were collected from four groups of rats: Sham + Vehicle; Sham + Gleevec; ICH + Vehicle; ICH + Gleevec. Microscopy revealed that cortical vessels in both ipsi- and contralateral hemispheres exhibited significantly reduced density and branching by 22 and 34%, respectively. Fractal measures confirmed reduced complexity as well. Gleevec treatment further reduced vascular parameters, including reductions in vessel density in tissues adjacent to the ICH. The reductions in brain wide vascular networks after Gleevec in the current study after ICH is contrasted by previous reports of improved behavioral outcomes and decreased lCH lesion volumes Reductions in the vascular network after Gleevec may be involved in long-term repair mechanisms by pruning injured vessels to ultimately promote new vessel growth.

Activation of melanocortin receptor 4 with RO27-3225 attenuates neuroinflammation through AMPK/JNK/p38 MAPK pathway after intracerebral hemorrhage in mice

Background

Neuroinflammation plays an important role in the pathogenesis of intracerebral hemorrhage (ICH)-induced secondary brain injury. Activation of melanocortin receptor 4 (MC4R) has been shown to elicit anti-inflammatory effects in many diseases. The objective of this study was to explore the role of MC4R activation on neuroinflammation in a mouse ICH model and to investigate the contribution of adenosine monophosphate-activated protein kinase (AMPK)/c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (p38 MAPK) pathway in MC4R-mediated protection.

Methods

Adult male CD1 mice (n = 189) were subjected to intrastriatal injection of bacterial collagenase or sham surgery. The selective MC4R agonist RO27-3225 was administered by intraperitoneal injection at 1 h after collagenase injection. The specific MC4R antagonist HS024 and selective AMPK inhibitor dorsomorphin were administered prior to RO27-3225 treatment to elucidate potential mechanism. Short- and long-term neurobehavioral assessments, brain water content, immunofluorescence staining, and western blot were performed.

Results

The expression of MC4R and p-AMPK increased after ICH with a peak at 24 h. MC4R was expressed by microglia, neurons, and astrocytes. Activation of MC4R with RO27-3225 improved the neurobehavioral functions, decreased brain edema, and suppressed microglia/macrophage activation and neutrophil infiltration after ICH. RO27-3225 administration increased the expression of MC4R and p-AMPK while decreasing p-JNK, p-p38 MAPK, TNF-α, and IL-1β expression, which was reversed with inhibition of MC4R and AMPK.

Conclusions

Our study demonstrated that activation of MC4R with RO27-3225 attenuated neuroinflammation through AMPK-dependent inhibition of JNK and p38 MAPK signaling pathway, thereby reducing brain edema and improving neurobehavioral functions after experimental ICH in mice. Therefore, the activation of MC4R with RO27-3225 may be a potential therapeutic approach for ICH management.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1140-6) contains supplementary material, which is available to authorized users.

A composite neurobehavioral test to evaluate acute functional deficits after cerebellar haemorrhage in rats

Cerebellar haemorrhage accounts for 5-10% of all intracerebral haemorrhages and leads to severe, long-lasting functional deficits. Currently, there is limited research on this stroke subtype, which may be due to the lack of a suitable composite neuroscoring system specific for cerebellar injury in rodents. The purpose of this study is to develop a comprehensive composite neuroscore test for cerebellar injury using a rat model of cerebellar haemorrhage. Sixty male Sprague-Dawley rats were subjected to either sham surgery or cerebellar haemorrhage. Twenty-four hours post-injury, neurological behaviour was evaluated using 17 cost-effective and easy-to-perform tests, and a composite neuroscore was developed. The composite neuroscore was then used to assess functional recovery over seven days after cerebellar haemorrhage. Differences in the composite neuroscore deficits for the mild and moderate cerebellar haemorrhage models were observed for up to five days post-ictus. Until now, a composite neuroscore for cerebellar injury was not available for rodent studies. Herein, using mild and moderate cerebellar haemorrhage rat models a composite neuroscore for cerebellar injury was developed and used to assess functional deficits after cerebellar haemorrhage. This composite neuroscore may also be useful for other cerebellar injury models.

IRE1α inhibition decreased TXNIP/NLRP3 inflammasome activation through miR-17-5p after neonatal hypoxic-ischemic brain injury in rats

Background

The endoplasmic reticulum (ER) is responsible for the control of correct protein folding and protein function which is crucial for cell survival. However, under pathological conditions, such as hypoxia–ischemia (HI), there is an accumulation of unfolded proteins thereby triggering the unfolded protein response (UPR) and causing ER stress which is associated with activation of several stress sensor signaling pathways, one of them being the inositol requiring enzyme-1 alpha (IRE1α) signaling pathway. The UPR is regarded as a potential contributor to neuronal cell death and inflammation after HI. In the present study, we sought to investigate whether microRNA-17 (miR-17), a potential IRE1α ribonuclease (RNase) substrate, arbitrates downregulation of thioredoxin-interacting protein (TXNIP) and consequent NLRP3 inflammasome activation in the immature brain after HI injury and whether inhibition of IRE1α may attenuate inflammation via miR-17/TXNIP regulation.

Methods

Postnatal day 10 rat pups (n = 287) were subjected to unilateral carotid artery ligation followed by 2.5 h of hypoxia (8% O₂). STF-083010, an IRE1α RNase inhibitor, was intranasally delivered at 1 h post-HI or followed by an additional one administration per day for 2 days. MiR-17-5p mimic or anti-miR-17-5p inhibitor was injected intracerebroventricularly at 48 h before HI. Infarct volume and body weight were used to evaluate the short-term effects while brain weight, gross and microscopic brain tissue morphologies, and neurobehavioral tests were conducted for the long-term evaluation. Western blots, immunofluorescence staining, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), and co-immunoprecipitation (Co-IP) were used for mechanism studies.

Results

Endogenous phosphorylated IRE1α expression was significantly increased after HI. Intranasal administration of STF-083010 alleviated brain injury and improved neurological behavior. MiR-17-5p expression was reduced after HI, and this decrease was attenuated by STF-083010 treatment. MiR-17-5p mimic administration ameliorated TXNIP expression, NLRP3 inflammasome activation, caspase-1 cleavage, and IL-1β production, as well as brain infarct volume. Conversely, anti-miR-17-5p inhibitor reversed IRE1α inhibition-induced decrease in TXNIP expression and inflammasome activation, as well as exacerbated brain injury after HI.

Conclusions

IRE1a-induced UPR pathway may contribute to inflammatory activation and brain injury following neonatal HI. IRE1a activation, through decay of miR-17-5p, elevated TXNIP expression to activate NLRP3 inflammasome and aggravated brain damage.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1077-9) contains supplementary material, which is available to authorized users.

Activation of dopamine D1 receptor decreased NLRP3-mediated inflammation in intracerebral hemorrhage mice

Background

Inflammasomes are involved in diverse inflammatory diseases. Previous study reported that the neurotransmitter dopamine inhibited NLRP3 inflammasome activation via dopamine D1 receptor (DRD1). The present study aims to investigate the role of DRD1 on neuroinflammation in intracerebral hemorrhage (ICH) mice and the potential mechanism mediated by NLRP3 inhibition.

Methods

One hundred and six male CD-1 mice were subjected to intrastriatal injection of bacterial collagenase or PBS. A68930 (DRD1 specific agonist) was administered by subcutaneous injection at 1 h after collagenase injection. Behavioral deficits and brain water content were assayed. The expression of Iba 1 and MPO levels were measured by immunofluorescence staining. The expressions of proteins in the DRD1/interferon-beta (IFN-beta)/NLRP3 signaling pathway were evaluated by western blotting.

Results

Activation of the DRD1 by A68930 decreased brain edema and improved behavior at 24 and 72 h of ICH. A68930 inhibited partly the activation of microglia and the neutrophil infiltration after 24 h of ICH. IFN-beta, p-STAT1 increased while NLRP3, caspase 1, and IL-1beta decreased after A68930 administration in ICH mice. DRD1 antagonist and IFN-beta siRNA reversed effects of A68930 on neurological outcome and brain edema. DRD1 antagonist and IFN-beta siRNA blocked not only A68930-mediated increases of IFN-beta, p-STAT1 but also A68930-mediated decreases of NLRP3, caspase 1, and IL-1beta.

Conclusions

DRD1 activation by A68930 improves neurological outcome through inhibition of NLRP3-mediated inflammation in ICH mice.

Electronic supplementary material

The online version of this article (10.1186/s12974-017-1039-7) contains supplementary material, which is available to authorized users.

Inhibition of stress fiber formation preserves blood-brain barrier after intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH) represents the deadliest subtype of all strokes. The development of brain edema, a consequence of blood-brain barrier (BBB) disruption, is the most life-threatening event after ICH. Pathophysiological conditions activate the endothelium, one of the components of BBB, inducing rearrangement of the actin cytoskeleton. Upon activation, globular actin assembles into a filamentous actin resulting in the formation of contractile actin bundles, stress fibers. The contraction of stress fibers leads to the formation of intercellular gaps between endothelial cells increasing the permeability of BBB. In the present study, we investigated the effect of ICH on stress fiber formation in CD1 mice. We hypothesized that ICH-induced formation of stress fiber is triggered by the activation of PDGFR-β and mediated by the cortactin/RhoA/LIMK pathway. We demonstrated that ICH induces formation of stress fibers. Furthermore, we demonstrated that the inhibition of PDGFR-β and its downstream reduced the number of stress fibers, preserving BBB and resulting in the amelioration of brain edema and improvement of neurological functions in mice after ICH.

Adropin preserves the blood-brain barrier through a Notch1/Hes1 pathway after intracerebral hemorrhage in mice

Adropin is expressed in the CNS and plays a crucial role in the development of stroke. However, little is currently known about the effects of adropin on the blood-brain barrier (BBB) function after intracerebral hemorrhage (ICH). In this study, the role of adropin in collagenase-induced ICH was investigated in mice. At 1-h post-ICH, mice were administered with recombinant human adropin by intranasal. Brain water +content, BBB permeability, and neurological function were measured at different time intervals. Proteins were quantified using western blot analysis, and the localizations of adropin and Notch1 were visualized via immunofluorescence staining. It is shown that adropin reduced brain water content and improved neurological functions. Adropin preserved the functionality of BBB by increasing N-cadherin expression and reducing extravasation of albumin. Moreover, in vivo knockdown of Notch1 and Hes1 both abolished the protective effects of adropin. Taken together, our data demonstrate that adropin constitutes a potential treatment value for ICH by preserving BBB and improving functional outcomes through the Notch1 signaling pathway.

Low-density lipoprotein receptor-related protein-1 facilitates heme scavenging after intracerebral hemorrhage in mice

Heme-degradation after erythrocyte lysis plays an important role in the pathophysiology of intracerebral hemorrhage. Low-density lipoprotein receptor-related protein-1 is a receptor expressed predominately at the neurovascular interface, which facilitates the clearance of the hemopexin and heme complex. In the present study, we investigated the role of low-density lipoprotein receptor-related protein-1 in heme removal and neuroprotection in a mouse model of intracerebral hemorrhage. Endogenous low-density lipoprotein receptor-related protein-1 and hemopexin were increased in ipsilateral brain after intracerebral hemorrhage, accompanied by increased hemoglobin levels, brain water content, blood-brain barrier permeability and neurological deficits. Exogenous human recombinant low-density lipoprotein receptor-related protein-1 protein reduced hematoma volume, brain water content surrounding hematoma, blood-brain barrier permeability and improved neurological function three days after intracerebral hemorrhage. The expression of malondialdehyde, fluoro-Jade C positive cells and cleaved caspase 3 was increased three days after intracerebral hemorrhage in the ipsilateral brain tissues and decreased with recombinant low-density lipoprotein receptor-related protein-1. Intracerebral hemorrhage decreased and recombinant low-density lipoprotein receptor-related protein-1 increased the levels of superoxide dismutase 1. Low-density lipoprotein receptor-related protein-1 siRNA reduced the effect of human recombinant low-density lipoprotein receptor-related protein-1 on all outcomes measured. Collectively, our findings suggest that low-density lipoprotein receptor-related protein-1 contributed to heme clearance and blood-brain barrier protection after intracerebral hemorrhage. The use of low-density lipoprotein receptor-related protein-1 as supplement provides a novel approach to ameliorating intracerebral hemorrhage brain injury via its pleiotropic neuroprotective effects.

Intranasal Administration of Interferon Beta Attenuates Neuronal Apoptosis via the JAK1/STAT3/BCL-2 Pathway in a Rat Model of Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy (HIE) is an injury that often leads to detrimental neurological deficits. Currently, there are no established therapies for HIE and it is critical to develop treatments that provide protection after HIE. The objective of this study was to investigate the ability of interferon beta (IFNβ) to provide neuroprotection and reduce apoptosis after HIE. Postnatal Day 10 rat pups were subjected to unilateral carotid artery ligation followed by 2.5 hr of exposure to hypoxia (8% O2). Intranasal administration of human recombinant IFNβ occurred 2 hr after HIE and infarct volume, body weight, neurobehavioral tests, histology, immunohistochemistry, brain water content, blood-brain barrier permeability, enzyme-linked immunosorbent assay, and Western blot were all used to evaluate various parameters. The results showed that both IFNβ and the Type 1 interferon receptor expression decreases after HIE. Intranasal administration of human recombinant IFNβ was able to be detected in the central nervous system and was able to reduce brain infarction volumes and improve neurological behavior tests 24 hr after HIE. Western blot analysis also revealed that human recombinant IFNβ treatment stimulated Stat3 and Bcl-2 expression leading to a decrease in cleaved caspase-3 expression after HIE. Positive Fluoro-Jade C staining also demonstrated that IFNβ treatment was able to decrease neuronal apoptosis. Furthermore, the beneficial effects of IFNβ treatment were reversed when a Stat3 inhibitor was applied. Also an intraperitoneal administration of human recombinant IFNβ into the systemic compartment was unable to confer the same protective effects as intranasal IFNβ treatment.