Anti-inflammatory effects of ADAMTS-4 in a mouse model of ischemic stroke

The Transcriptional Landscape of Pericytes in Acute Ischemic Stroke

The current treatment options for ischemic stroke aim to achieve reperfusion but are time critical. Novel therapeutic approaches that can be given beyond the limited time window of 3-4.5 h are still an unmet need to be addressed to improve stroke outcomes. The lack of oxygen and glucose in the area of ischemic injury initiates a pathological cascade leading to blood-brain barrier (BBB) breakdown, inflammation, and neuronal cell death, a process that may be intercepted to limit stroke progression. Pericytes located at the blood/brain interface are one of the first responders to hypoxia in stroke and therefore a potential target cell for early stroke interventions. Using single-cell RNA sequencing in a mouse model of permanent middle cerebral artery occlusion, we investigated the temporal differences in transcriptomic signatures in pericytes at 1, 12, and 24 h after stroke. Our results reveal a stroke-specific subcluster of pericytes that is present at 12 and 24 h and characterized by the upregulation of genes mainly related to cytokine signaling and immune response. This study identifies temporal transcriptional changes in the acute phase of ischemic stroke that reflect the early response of pericytes to the ischemic insult and its secondary consequences and may constitute potential future therapeutic targets.

Cellular Components of the Blood-Brain Barrier and Their Involvement in Aging-Associated Cognitive Impairment

Human life expectancy has been significantly extended, which poses major challenges to our healthcare and social systems. Aging-associated cognitive impairment is attributed to endothelial dysfunction in the cardiovascular system and neurological dysfunction in the central nervous system. The central nervous system is considered an immune-privileged tissue due to the exquisite protection provided by the blood-brain barrier. The present review provides an overview of the structure and function of blood-brain barrier, extending the cell components of blood-brain barrier from endothelial cells and pericytes to astrocytes, perivascular macrophages and oligodendrocyte progenitor cells. In particular, the pathological changes in the blood-brain barrier in aging, with special focus on the underlying mechanisms and molecular changes, are presented. Furthermore, the potential preventive/therapeutic strategies against aging-associated blood-brain barrier disruption are discussed.

Epigenetic Up-Regulation of ADAMTS4 in Sympathetic Ganglia is Involved in the Maintenance of Neuropathic Pain Following Nerve Injury

Sympathetic axonal sprouting into dorsal root ganglia is a major phenomenon implicated in neuropathic pain, and sympathetic ganglia blockage may relieve some intractable chronic pain in animal pain models and clinical conditions. These suggest that sympathetic ganglia participated in the maintenance of chronic pain. However, the molecular mechanism underlying sympathetic ganglia-mediated chronic pain is not clear. Here, we found that spared nerve injury treatment upregulated the expression of ADAMTS4 and AP-2α protein and mRNA in the noradrenergic neurons of sympathetic ganglia during neuropathic pain maintenance. Knockdown the ADAMTS4 or AP-2α by injecting specific retro scAAV-TH (Tyrosine Hydroxylase)-shRNA ameliorated the mechanical allodynia induced by spared nerve injury on day 21 and 28. Furthermore, chromatin immunoprecipitation and coimmunoprecipitation assays found that spared nerve injury increased the recruitment of AP-2α to the ADAMTS4 gene promoter, the interaction between AP-2α and histone acetyltransferase p300 and the histone H4 acetylation on day 28. Finally, knockdown the AP-2α reduced the acetylation of H4 on the promoter region of ADAMTS4 gene and suppressed the increase of ADAMTS4 expression induced by spared nerve injury. Together, these results suggested that the enhanced interaction between AP-2α and p300 mediated the epigenetic upregulation of ADAMTS4 in sympathetic ganglia noradrenergic neurons, which contributed to the maintenance of spared nerve injury induced neuropathic pain.

Transplanted human iPSC-derived vascular endothelial cells promote functional recovery by recruitment of regulatory T cells to ischemic white matter in the brain

BACKGROUND

Ischemic stroke in white matter of the brain induces not only demyelination, but also neuroinflammation. Peripheral T lymphocytes, especially regulatory T cells (Tregs), are known to infiltrate into ischemic brain and play a crucial role in modulation of inflammatory response there. We previously reported that transplantation of vascular endothelial cells generated from human induced pluripotent stem cells (iVECs) ameliorated white matter infarct. The aim of this study is to investigate contribution of the immune system, especially Tregs, to the mechanism whereby iVEC transplantation ameliorates white matter infarct.

METHODS

iVECs and human Tregs were transplanted into the site of white matter lesion seven days after induction of ischemia. The egress of T lymphocytes from lymph nodes was sequestered by treating the animals with fingolimod (FTY720). The infarct size was evaluated by magnetic resonance imaging. Immunohistochemistry was performed to detect the activated microglia and macrophages, T cells, Tregs, and oligodendrocyte lineage cells. Remyelination was examined by Luxol fast blue staining.

RESULTS

iVEC transplantation reduced ED-1⁺ inflammatory cells and CD4⁺ T cells, while increased Tregs in the white matter infarct. Treatment of the animals with FTY720 suppressed neuroinflammation and reduced the number of both CD4⁺ T cells and Tregs in the lesion, suggesting the importance of infiltration of these peripheral immune cells into the lesion in aggravation of neuroinflammation. Suppression of neuroinflammation by FTY720 per se, however, did not promote remyelination in the infarct. FTY720 treatment negated the increase in the number of Tregs by iVEC transplantation in the infarct, and attenuated remyelination promoted by transplanted iVECs, while it did not affect the number of oligodendrocyte lineage cells increased by iVEC transplantation. Transplantation of Tregs together with iVECs into FTY720-treated ischemic white matter did not affect the number of oligodendrocyte lineage cells, while it remarkably promoted myelin regeneration.

CONCLUSIONS

iVEC transplantation suppresses neuroinflammation, but suppression of neuroinflammation per se does not promote remyelination. Recruitment of Tregs by transplanted iVECs contributes significantly to promotion of remyelination in the injured white matter.

ADAM and ADAMTS disintegrin and metalloproteinases as major factors and molecular targets in vascular malfunction and disease

A Disintegrin and Metalloproteinase (ADAM) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs (ADAMTS) are two closely related families of proteolytic enzymes. ADAMs are largely membrane-bound enzymes that act as molecular scissors or sheddases of membrane-bound proteins, growth factors, cytokines, receptors and ligands, whereas ADAMTS are mainly secreted enzymes. ADAMs have a pro-domain, and a metalloproteinase, disintegrin, cysteine-rich and transmembrane domain. Similarly, ADAMTS family members have a pro-domain, and a metalloproteinase, disintegrin, and cysteine-rich domain, but instead of a transmembrane domain they have thrombospondin motifs. Most ADAMs and ADAMTS are activated by pro-protein convertases, and can be regulated by G-protein coupled receptor agonists, Ca²⁺ ionophores and protein kinase C. Activated ADAMs and ADAMTS participate in numerous vascular processes including angiogenesis, vascular smooth muscle cell proliferation and migration, vascular cell apoptosis, cell survival, tissue repair, and wound healing. ADAMs and ADAMTS also play a role in vascular malfunction and cardiovascular diseases such as hypertension, atherosclerosis, coronary artery disease, myocardial infarction, heart failure, peripheral artery disease, and vascular aneurysm. Decreased ADAMTS13 is involved in thrombotic thrombocytopenic purpura and microangiopathies. The activity of ADAMs and ADAMTS can be regulated by endogenous tissue inhibitors of metalloproteinases and other synthetic small molecule inhibitors. ADAMs and ADAMTS can be used as diagnostic biomarkers and molecular targets in cardiovascular disease, and modulators of ADAMs and ADAMTS activity may provide potential new approaches for the management of cardiovascular disorders.

Disorder Genes Regulate the Progression of Ischemic Stroke through the NF-κB Signaling Pathway

Stroke is an acute cerebrovascular disease, including ischemic and hemorrhagic stroke. Stroke is the second leading cause of death after ischemic heart disease, which accounts for 9% of the global death toll. To explore the molecular mechanisms of the effects of the dysregulated factors, in the GEO database, we obtained transcriptome data from 24 h/72 h of mice with ischemic stroke and 24 h/72 h of normal mice. We then performed differential gene analysis, coexpression analysis, enrichment analysis, and regulator prediction bioinformatics analysis to identify the potential genes. We made a comparison between the ischemic stroke 72 h and the ischemic stroke for 24 h, and 5103 differential genes were obtained (p < 0.05). Four functional barrier modules were obtained by weighted gene coexpression network analysis. The critical genes of each module were ASTL, Zfp472, Fmr1 gene, and Nap1l1. The results of the enrichment analysis showed ncRNA metabolism, microRNAs in cancer, and biosynthesis of amino acids. These three functions and pathways have the most considerable count value. The regulators of the regulatory dysfunction module were predicted by pivotal analysis of TF and noncoding RNA, and critical regulators including NFKB1 (NF-κB1), NFKBIA, CTNNB1, and SP1 were obtained. Finally, the pivotal target gene found that CTNNB1, NFKB1, NFKBia, and Sp1 are involved in 18, 32, 2, and 60 target genes, respectively. Therefore, we believe that NFKB1 and Sp1 have a potential role in the progression of ischemic stroke. The NFKB signaling pathway promotes inflammatory cytokines and regulates the progression of ischemic stroke.

Endothelial glycocalyx in traumatic brain injury associated coagulopathy: potential mechanisms and impact

Traumatic brain injury (TBI) remains one of the leading causes of death and disability worldwide; more than 10 million people are hospitalized for TBI every year around the globe. While the primary injury remains unavoidable and not accessible to treatment, the secondary injury which includes oxidative stress, inflammation, excitotoxicity, but also complicating coagulation abnormalities, is potentially avoidable and profoundly affects the therapeutic process and prognosis of TBI patients. The endothelial glycocalyx, the first line of defense against endothelial injury, plays a vital role in maintaining the delicate balance between blood coagulation and anticoagulation. However, this component is highly vulnerable to damage and also difficult to examine. Recent advances in analytical techniques have enabled biochemical, visual, and computational investigation of this vascular component. In this review, we summarize the current knowledge on (i) structure and function of the endothelial glycocalyx, (ii) its potential role in the development of TBI associated coagulopathy, and (iii) the options available at present for detecting and protecting the endothelial glycocalyx.

Internal modulation of proteolysis in vascular extracellular matrix remodeling: role of ADAM metallopeptidase with thrombospondin type 1 motif 5 in the development of intracranial aneurysm rupture

Intracranial aneurysms (IAs) are common cerebrovascular diseases that carry a high mortality rate, and the mechanisms that contribute to IA formation and rupture have not been elucidated. ADAMTS-5 (ADAM Metallopeptidase with Thrombospondin Type 1 Motif 5) is a secreted proteinase involved in matrix degradation and ECM (extracellular matrix) remodeling processes, and we hypothesized that the dysregulation of ADAMTS-5 could play a role in the pathophysiology of IA. Immunofluorescence revealed that the ADAMTS-5 levels were decreased in human and murine IA samples. The administration of recombinant protein ADAMTS-5 significantly reduced the incidence of aneurysm rupture in the experimental model of IA. IA artery tissue was collected and utilized for histology, immunostaining, and specific gene expression analysis. Additionally, the IA arteries in ADAMTS-5-administered mice showed reduced elastic fiber destruction, proteoglycan accumulation, macrophage infiltration, inflammatory response, and apoptosis. To further verify the role of ADAMTS-5 in cerebral vessels, a specific ADAMTS-5 inhibitor was used on another model animal, zebrafish, and intracranial hemorrhage was observed in zebrafish embryos. In conclusion, our findings indicate that ADAMTS-5 is downregulated in human IA, and compensatory ADAMTS-5 administration inhibits IA development and rupture with potentially important implications for treating this cerebrovascular disease.

Kellerin from Ferula sinkiangensis exerts neuroprotective effects after focal cerebral ischemia in rats by inhibiting microglia-mediated inflammatory responses

ETHNOPHARMACOLOGICAL RELEVANCE

Ferula sinkiangensis K. M. Shen is a traditional Chinese medicine that has a variety of pharmacological properties relevant to neurological disorders and inflammations. Kellerin, a novel compound extracted from Ferula sinkiangensis, exerts a strong anti-neuroinflammatory effect by inhibiting microglial activation. Microglial activation plays a vital role in ischemia-induced brain injury. However, the potential therapeutic effect of kellerin on focal cerebral ischemia is still unknown.

AIM OF THE STUDY

To explore the effect of kellerin on cerebral ischemia and clarify its possible mechanisms, we applied the middle cerebral artery occlusion (MCAO) model and the LPS-activated microglia model in our study.

MATERIALS AND METHODS

Neurological outcome was examined according to a 4-tiered grading system. Brain infarct size was measured using TTC staining. Brain edema was calculated using the wet weight minus dry weight method. Neuron damage and microglial activation were observed by immunofluorescence in MCAO model in rats. In in vitro studies, microglial activation was examined by flow cytometry and the viability of neuronal cells cultured in microglia-conditioned medium was measured using MTT assay. The levels of pro-inflammatory cytokines were measured by qRT-PCR and ELISA. The proteins involved in NF-κB signaling pathway were determined by western blot. Intracellular ROS was examined using DCFH-DA method and NADPH oxidase activity was measured using the NBT assay.

RESULTS

We found that kellerin improved neurological outcome, reduced brain infarct size and decreased brain edema in MCAO model in rats. Under the pathologic conditions of focal cerebral ischemia, kellerin alleviated neuron damage and inhibited microglial activation. Moreover, in in vitro studies of LPS-stimulated BV2 cells kellerin protected neuronal cells from being damaged by inhibiting microglial activation. Kellerin also reduced the levels of pro-inflammatory cytokines, suppressed the NF-κB signaling pathway, and decreased ROS generation and NADPH oxidase activity.

CONCLUSIONS

Our discoveries reveal that the neuroprotective effects of kellerin may largely depend on its inhibitory effect on microglial activation. This suggests that kellerin could serve as a novel anti-inflammatory agent which may have therapeutic effects in ischemic stroke.

Effect of memantine, an anti-Alzheimer's drug, on rodent microglial cells in vitro

The pathophysiology of Alzheimer's disease (AD) is related to neuroinflammatory responses mediated by microglia. Memantine, an antagonist of N-methyl-D-aspartate (NMDA) receptors used as an anti-Alzheimer's drug, protects from neuronal death accompanied by suppression of proliferation and activation of microglial cells in animal models of AD. However, it remains to be tested whether memantine can directly affect microglial cell function. In this study, we examined whether pretreatment with memantine affects intracellular NO and Ca2+ mobilization using DAF-2 and Fura-2 imaging, respectively, and tested the effects of memantine on phagocytic activity by human β-Amyloid (1-42) phagocytosis assay in rodent microglial cells. Pretreatment with memantine did not affect production of NO or intracellular Ca2+ elevation induced by TNF in rodent microglial cells. Pretreatment with memantine also did not affect the mRNA expression of pro-inflammatory (TNF, IL-1β, IL-6 and CD45) or anti-inflammatory (IL-10, TGF-β and arginase) phenotypes in rodent microglial cells. In addition, pretreatment with memantine did not affect the amount of human β-Amyloid (1-42) phagocytosed by rodent microglial cells. Moreover, we observed that pretreatment with memantine did not affect 11 major proteins, which mainly function in the phagocytosis and degradation of β-Amyloid (1-42), including TREM2, DAP12 and neprilysin in rodent microglial cells. To the best of our knowledge, this is the first report to suggest that memantine does not directly modulate intracellular NO and Ca2+ mobilization or phagocytic activity in rodent microglial cells. Considering the neuroinflammation hypothesis of AD, the results might be important to understand the effect of memantine in the brain.

ADAMTS proteases and the tumor immune microenvironment: Lessons from substrates and pathologies

The relationship of ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) proteases with inflammatory processes was anticipated since their discovery. Although knowledge of these extracellular proteases in different contexts continues to grow, many questions remain unanswered. In this review, we summarize the most important studies of ADAMTSs and their substrates in inflammation and in the immune system of non-oncological disorders. In addition, we update the findings on cancer and highlight their emerging role in the tumor immune microenvironment. Although the overall functions of extracellular molecules are known to be modulated by proteolysis, specific activities attributed to intact proteins and cleaved fragments in the context of inflammation are still subject to debate. A better understanding of ADAMTS activities will help to elucidate their contribution to the immune phenotype and to open up new therapeutic and diagnostic possibilities.

Upregulation of TNF-α and IL-6 induces preterm premature rupture of membranes by activation of ADAMTS-9 in embryonic membrane cells

AIM

To investigate the role of thrombospondin motifs 9 (ADAMTS9) in preterm premature rupture of membranes (pPROM).

MATERIALS AND METHODS

ADAMTS9 levels were measured in amnion cells from 24 patients of different groups (preterm vs. full-term birth, with vs. without PROM). ADAMTS9 was suppressed in human amnioblasts to investigate its effects on embryonic membrane cells and inflammation-induced cell damage. Pregnant mouse models were used to assess whether inflammation regulates ADAMTS9 by upregulating TNF-α and IL-6, contributing to the preterm birth occurrence.

KEY FINDINGS

We found that ADAMTS9 protein and gene expression levels significantly differed among various groups (pPROM > full-term PROM > preterm non-PROM > full-term non-PROM). After ADAMTS9 suppression in human amnioblast WISH cells, TNF-α- and IL-6-induced apoptosis was decreased. In addition, TNF-α, IL-6, and ADAMTS9 protein and gene expression levels were increased in the embryos of mice treated with LPS compared with controls. In agreement, the rate of preterm birth was higher in the LPS group compared with controls.

SIGNIFICANCE

Taken together, these in vitro and in vivo findings suggest that TNF-α and IL-6 secreted by macrophages during inflammation regulate ADAMTS9 and induce pPROM.

MiR-126a-5p limits the formation of abdominal aortic aneurysm in mice and decreases ADAMTS-4 expression

Abdominal aortic aneurysm (AAA) is a serious vascular disease featured by inflammatory infiltration in aortic wall, aortic dilatation and extracellular matrix (ECM) degradation. Dysregulation of microRNAs (miRNAs) is implicated in AAA progress. By profiling miRNA expression in mouse AAA tissues and control aortas, we noted that miR-126a-5p was down-regulated by 18-fold in AAA samples, which was further validated with real-time qPCR. This study was performed to investigate miR-126a-5p's role in AAA formation. In vivo, a 28-d infusion of 1 μg/kg/min Angiotensin (Ang) II was used to induce AAA formation in Apoe-/- mice. MiR-126a-5p (20 mg/kg; MIMAT0000137) or negative control (NC) agomirs were intravenously injected to mice on days 0, 7, 14 and 21 post-Ang II infusion. Our data showed that miR-126a-5p overexpression significantly improved the survival and reduced aortic dilatation in Ang II-infused mice. Elastic fragment and ECM degradation induced by Ang II were also ameliorated by miR-126a-5p. A strong up-regulation of ADAM metallopeptidase with thrombospondin type 1 motif 4 (ADAMTS-4), a secreted proteinase that regulates matrix degradation, was observed in smooth muscle cells (SMCs) of aortic tunica media, which was inhibited by miR-126a-5p. Dual-luciferase results demonstrated ADAMTS-4 as a new and valid target for miR-126a-5p. In vitro, human aortic SMCs (hASMCs) were stimulated by Ang II. Gain- and loss-of-function experiments further confirmed that miR-126-5p prevented Ang II-induced ECM degradation, and reduced ADAMTS-4 expression in hASMCs. In summary, our work demonstrates that miR-126a-5p limits experimental AAA formation and reduces ADAMTS-4 expression in abdominal aortas.

Intracerebral overexpression of miR-669c is protective in mouse ischemic stroke model by targeting MyD88 and inducing alternative microglial/macrophage activation

Background

Ischemic stroke is a devastating disease without a cure. The available treatments for ischemic stroke, thrombolysis by tissue plasminogen activator, and thrombectomy are suitable only to a fraction of patients and thus novel therapeutic approaches are urgently needed. The neuroinflammatory responses elicited secondary to the ischemic attack further aggravate the stroke-induced neuronal damage. It has been demonstrated that these responses are regulated at the level of non-coding RNAs, especially miRNAs.

Methods

We utilized lentiviral vectors to overexpress miR-669c in BV2 microglial cells in order to modulate their polarization. To detect whether the modulation of microglial activation by miR-669c provides protection in a mouse model of transient focal ischemic stroke, miR-669c overexpression was driven by a lentiviral vector injected into the striatum prior to induction of ischemic stroke.

Results

Here, we demonstrate that miR-669c-3p, a member of chromosome 2 miRNA cluster (C2MC), is induced upon hypoxic and excitotoxic conditions in vitro and in two different in vivo models of stroke. Rather than directly regulating the neuronal survival in vitro, miR-669c is capable of attenuating the microglial proinflammatory activation in vitro and inducing the expression of microglial alternative activation markers arginase 1 (Arg1), chitinase-like 3 (Ym1), and peroxisome proliferator-activated receptor gamma (PPAR-γ). Intracerebral overexpression of miR-669c significantly decreased the ischemia-induced cell death and ameliorated the stroke-induced neurological deficits both at 1 and 3 days post injury (dpi). Albeit miR-669c overexpression failed to alter the overall Iba1 protein immunoreactivity, it significantly elevated Arg1 levels in the ischemic brain and increased colocalization of Arg1 and Iba1. Moreover, miR-669c overexpression under cerebral ischemia influenced several morphological characteristics of Iba1 positive cells. We further demonstrate the myeloid differentiation primary response gene 88 (MyD88) transcript as a direct target for miR-669c-3p in vitro and show reduced levels of MyD88 in miR-669c overexpressing ischemic brains in vivo.

Conclusions

Collectively, our data provide the evidence that miR-669c-3p is protective in a mouse model of ischemic stroke through enhancement of the alternative microglial/macrophage activation and inhibition of MyD88 signaling. Our results accentuate the importance of controlling miRNA-regulated responses for the therapeutic benefit in conditions of stroke and neuroinflammation.

New Insights into ADAMTS Metalloproteases in the Central Nervous System

Components of the extracellular matrix (ECM) are key players in regulating cellular functions throughout the whole organism. In fact, ECM components not only participate in tissue organization but also contribute to processes such as cellular maintenance, proliferation, and migration, as well as to support for various signaling pathways. In the central nervous system (CNS), proteoglycans of the lectican family, such as versican, aggrecan, brevican, and neurocan, are important constituents of the ECM. In recent years, members of this family have been found to be involved in the maintenance of CNS homeostasis and to participate directly in processes such as the organization of perineural nets, the regulation of brain plasticity, CNS development, brain injury repair, axonal guidance, and even the altering of synaptic responses. ADAMTSs are a family of “A disintegrin and metalloproteinase with thrombospondin motifs” proteins that have been found to be involved in a multitude of processes through the degradation of lecticans and other proteoglycans. Recently, alterations in ADAMTS expression and activity have been found to be involved in neuronal disorders such as stroke, neurodegeneration, schizophrenia, and even Alzheimer’s disease, which in turn may suggest their potential use as therapeutic targets. Herein, we summarize the different roles of ADAMTSs in regulating CNS events through interactions and the degradation of ECM components (more specifically, the lectican family of proteoglycans).

Intracranial aneurysm's association with genetic variants, transcription abnormality, and methylation changes in ADAMTS genes

Purpose

The development of intracranial aneurysm (IA) has been linked to genetic factors. The current study examines the potential role of genes encoding disintegrin and metalloproteinase using thrombospondin motifs (ADAMTS) in IA development.

Material and Methods

High-throughput whole-genome and whole-exome sequencing were used when screening for deleterious single-nucleotide variants (SNVs) in ADAMTS genes using samples from 20 Han Chinese patients: 19 with familial IA and one patient with sporadic IA. The variant frequencies in these subjects were compared to those in control individuals found in the Genome Aggregation Database. Transcriptome sequencing and methylation sequencing data were retrieved from the Gene Expression Omnibus (GEO) database to identify differentially expressed ADAMTS genes and their methylation sites. We predicted the network of interactions among proteins encoded by the overlapping set of ADAMTS genes showing deleterious variants and both differential expression and abnormal methylation in IA. Possible candidate proteins linked to IA were validated using Western blot analysis. The associations between IA and SNVs rs11750568 in ADAMTS2, as well as rs2301612 and rs2285489 in ADAMTS13, were verified using the Sequenom MassArray system on a separate sample set of 595 Han Chinese patients with sporadic IA and 600 control individuals.

Results

A total of 16 deleterious variants in 13 ADAMTS genes were identified in our patients, and seven of these genes overlapped with the genes found to be differentially expressed and differentially methylated in the GEO database. Protein–protein interaction analysis predicted that ADAMTSL1 was at the center of the seven genes. ADAMTSL1 protein was lower expressed in IA tissue than in the control cerebral artery. Frequencies of the IA-related SNVs rs11750568 in ADAMTS2 and rs2301612 and rs2285489 in ADAMTS13 were not significantly different between sporadic IA patients and controls.

Conclusion

IA is associated with genetic variants, differential expression, and abnormal methylation in ADAMTS genes, ADAMTSL1 in particular.

Astrocyte-selective AAV-ADAMTS4 gene therapy combined with hindlimb rehabilitation promotes functional recovery after spinal cord injury

Chondroitin sulphate proteoglycans (CSPGs) are inhibitors to axon regeneration and plasticity. A disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS4) is a human enzyme that catalyses the proteolysis of CSPG protein cores. Infusion of ADAMTS4 into the damaged spinal cord was previously shown to improve functional recovery SCI, however, this therapy is limited in its enzyme form. Adeno-associated viral (AAV) vector gene therapy has emerged as the vector of choice for safe, robust and long-term transgene expression in the central nervous system. Here, an AAV expression cassette containing ADAMTS4 under the control of the astrocytic GfaABC₁D promoter was packaged into an AAV5 vector. Sustained expression of ADAMTS4 was achieved in vitro and in vivo leading to degradation of CSPGs. Compared to a contusion only group, AAV-ADAMTS4 resulted in significantly decreased lesion size, increased sprouting of hindlimb corticospinal tract axons, increased serotonergic fiber density caudal to a contusive spinal cord injury. Hindlimb-specific exercise rehabilitation was used to drive neuroplasticity towards improving functional connections. The combination of hindlimb rehabilitation with AAV-ADAMTS4 led to functional recovery after SCI compared to a contusion only group. Thus, long-term degradation of CSPGs through AAV-ADAMTS4 gene therapy in a combinational approach with rehabilitation represents a candidate for further preclinical development.

Persistent oppression and simple decompression both exacerbate spinal cord ascorbate levels

Background: Surgical decompression after acute spinal cord injury has become the consensus of orthopaedic surgeons. However, the choice of surgical decompression time window after acute spinal cord injury has been one of the most controversial topics in orthopaedics. Objective: We apply an online electrochemical system (OECS) for continuously monitoring the ascorbate of the rats' spinal cord to determine the extent to which ascorbate levels were influenced by contusion or sustained compression. Methods: Adult Sprague-Dawley rats (n=10) were instrumented for ascorbate concentration recording and received T11 drop spinal cord injury (SCI). The Group A (n=5) were treated with immediately decompression after SCI. The Group B (n=5) were contused and oppressed until 1 h after the injury to decompress. Results: The ascorbate level of spinal cord increased immediately by contusion injury and reached to 1.62 μmol/L ± 0.61 μmol/L (217.30% ± 95.09% of the basal level) at the time point of 60 min after the injury. Compared with the Group A, the ascorbate level in Group B increased more significantly at 1 h after the injury, reaching to 3.76 μmol/L ± 1.75 μmol/L (430.25% ± 101.30% of the basal level). Meanwhile, we also found that the decompression after 1 hour of continuous compression will cause delayed peaks of ascorbate reaching to 5.71 μmol/L ± 2.69 μmol/L (627.73% ± 188.11% of the basal level). Conclusion: Our study provides first-hand direct experimental evidence indicating ascorbate is directly involved in secondary spinal cord injury and exhibits the dynamic time course of microenvironment changes after continuous compression injury of the spinal cord.

Expression Profiles of Long Noncoding RNAs in Mice with High-Altitude Hypoxia-Induced Brain Injury Treated with Gymnadenia conopsea (L.) R. Br

BACKGROUND

The unique geographical environment at high altitudes may cause a series of diseases, such as acute altitude reaction, cerebral edema, and pulmonary edema. Gymnadenia conopsea (L.) R. Br. has been reported to have an effect on high-altitude hypoxia. However, the molecular mechanism, especially the expression of long noncoding RNAs (lncRNAs), is not yet clear.

METHODS

The expression profiles of lncRNAs in high-altitude hypoxia-induced brain injury mice treated with Gymnadenia conopsea (L.) R. Br. by using a microarray method.

RESULTS

A total of 226 differentially expressed lncRNAs, 126 significantly dysregulated mRNAs and 23 differentially expressed circRNAs were detected (>2.0-fold, p<0.05). The expression of selected lncRNAs, mRNAs and circRNAs was validated by qRT-PCR. KEGG analysis showed that the mRNAs coexpressed with lncRNAs were involved in inflammation and hypoxia pathways, including the HIF-1, PI3K-Akt, and NF-kappa B signaling pathways. The lncRNA-TF network analysis results indicated that the lncRNAs were regulated mostly by HMGA2, SRY, GATA4, SOX5, and ZBTB16.

CONCLUSION

This study is the first to report the expression profiles of lncRNAs, mRNAs and circRNAs in mice with high-altitude hypoxia-induced brain injury treated with Gymnadenia conopsea (L.) R. Br. and may improve the understanding of the molecular mechanism of Gymnadenia conopsea (L.) R. Br. in treating high altitude hypoxia-induced brain injury.

Monocarboxylate transporter 1 promotes classical microglial activation and pro-inflammatory effect via 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3

Background

Microglia, the resident macrophages of central nervous system, have been initially categorized into two opposite phenotypes: classical activation related to pro-inflammatory responses and alternative activation corresponding with anti-inflammatory reactions and tissue remodeling. The correlation between metabolic pattern and microglial activation has been identified. However, little is known about the mechanism of metabolism-mediated microglia polarization and pro-inflammatory effect.

Methods

Metabolic alteration was analyzed in different phenotypes of microglia in vitro. LPS-induced neuroinflammation and sickness behavior mouse model was used to investigate the effect of lactate on classical microglial activation in vivo.

Results

Glycolysis-related regulators, monocarboxylate transporter 1 (MCT1), MCT4, and pro-glycolytic enzyme 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3 (PFKFB3), were specifically increased in LPS-stimulated primary microglia and microglia cell line BV2. Knockdown of MCT1 suppressed glycolysis rate and decreased LPS-induced expression of iNOS, interleukin-1β (IL-1β), IL-6, and phosphorylation of STAT1 in BV2 cells. Importantly, MCT1 promoted PFKFB3 expression via hypoxia-inducible factor-1α (Hif-1α), and overexpression of PFKFB3 restored the classical activation of BV2 cells suppressed by MCT1 silence. All above strongly suggested that MCT1/PFKFB3 might accelerate LPS-induced classical polarization of microglia probably by promoting glycolysis. Interestingly, additional administration of moderate lactate, which may block the transport function of MCT1, decreased LPS-induced classical activation and expression of PFKFB3 in BV2 cells. Intracerebroventricular injection of lactate ameliorated LPS-induced sickness behavior and classical polarization of microglia in mice.

Conclusions

Our results demonstrate the key role of MCT1 in microglial classical activation and neuroinflammation in pathological conditions. In addition, lactate administration may be a potential therapy to suppress neuroinflammation by altering microglial polarization.

Inhibition of ADAMTS-4 Expression in Olfactory Ensheathing Cells Enhances Recovery after Transplantation within Spinal Cord Injury

Spinal cord injury (SCI) induces permanent loss of sensitive and motor functions below the injury level. To date, a wide variety of cells has been used as biotherapies to cure SCI in different animal paradigms. Specifically, olfactory ensheathing cells (OECs) is one of the most promising. Indeed, OECs have been shown to enhance recovery in many animal studies. Moreover, OECs transplantation has been applied to a paraplegic patient and have shown beneficial effects. However, it has been reported that the significant level of recovery varies among different patients. Therefore, it is of primary importance to enhance the regenerative efficiency of OECs for better translations. Recently, it has been shown that inhibiting ADAMTS4 expression in glial cells in vitro increases their synthesis of neurotrophic factors. We hypothesized that the expression of neurotrophic factors secreted by OECs can be increased by the deletion of ADAMTS4. Taking advantage of ADAMTS4^-/- mouse line, we produce ADAMTS4 deficient primary OEC cultures and then we investigated their regenerative potential after SCI. By using quantitative polymerase chain reaction, bioluminescence imaging, measurement of locomotor activity, electrophysiological studies, and immunohistochemistry, our results show that ADAMTS4^-/- olfactory bulb OEC (bOECs) primary cultures upregulate their trophic factor expression in vitro, and that the transplantation of ADAMTS4^-/- bOECs in a severe SCI model increases functional recovery and tissue repair in vivo. Altogether, our study reveals, for the first time, that primary bOEC cultures transplantation can be potentialized by inhibition of the expression of ADAMTS4.

Matrix metalloproteinases and ADAMs in stroke

Stroke is a leading cause of death and disability worldwide. However, after years of in-depth research, the pathophysiology of stroke is still not fully understood. Increasing evidence shows that matrix metalloproteinases (MMPs) and "a disintegrin and metalloproteinase" (ADAMs) participate in the neuro-inflammatory cascade that is triggered during stroke but also in recovery phases of the disease. This review covers the involvement of these proteins in brain injury following cerebral ischemia which has been widely studied in recent years, with efforts to modulate this group of proteins in neuroprotective therapies, together with their implication in neurorepair mechanisms. Moreover, the review also discusses the role of these proteins in specific forms of neurovascular disease, such as small vessel diseases and intracerebral hemorrhage. Finally, the potential use of MMPs and ADAMs as guiding biomarkers of brain injury and repair for decision-making in cases of stroke is also discussed.

CD4 T cell deficiency attenuates ischemic stroke, inhibits oxidative stress, and enhances Akt/mTOR survival signaling pathways in mice

Background

Inhibition of CD4 T cells reduces stroke-induced infarction by inhibiting neuroinflammation in the ischemic brain in experimental stroke. Nevertheless, little is known about its effects on neuronal survival signaling pathways. In this study, we investigated the effects of CD4 T cell deficits on oxidative stress and on the Akt/mTOR cell signaling pathways after ischemic stroke in mice.

Methods

MHC II gene knockout C57/BL6 mice, with significantly decreased CD4 T cells, were used. Stroke was induced by 60-min middle cerebral artery (MCA) occlusion. Ischemic brain tissues were harvested for Western blotting.

Results

The impairment of CD4 T cell production resulted in smaller infarction. The Western blot results showed that iNOS protein levels robustly increased at 5 h and 24 h and then returned toward baseline at 48 h in wild-type mice after stroke, and gene KO inhibited iNOS at 5 h and 24 h. In contrast, the anti-inflammatory marker, arginase I, was found increased after stroke in WT mice, which was further enhanced in the KO mice. In addition, stroke resulted in increased phosphorylated PTEN, Akt, PRAS40, P70S6, and S6 protein levels in WT mice, which were further enhanced in the animals whose CD4 T cells were impaired.

Conclusion

The impairment of CD4 T cell products prevents ischemic brain injury, inhibits inflammatory signals, and enhances the Akt/mTOR cell survival signaling pathways.

ADAMTS1 protease is required for a balanced immune cell repertoire and tumour inflammatory response

Recent advances have emphasized the relevance of studying the extracellular microenvironment given its main contribution to tissue homeostasis and disease. Within this complex scenario, we have studied the extracellular protease ADAMTS1 (a disintegrin and metalloprotease with thrombospondin motif 1), implicated in vascularization and development, with reported anti- and pro-tumorigenic activities. In this work we performed a detailed study of the vasculature and substrates in adult organs of wild type and Adamts1-deficient mice. In addition to the expected alterations of organs like kidney, heart and aorta, we found that the lack of ADAMTS1 differently affects lymphocyte and myeloid populations in the spleen and bone marrow. The study of the substrate versican also revealed its alteration in the absence of the protease. With such premises, we challenged our mice with subcutaneous B16F1 syngeneic tumours and closely evaluated the immune repertoire in the tumours but also in the distant spleen and bone marrow. Our results confirmed a pro-inflammatory landscape in the absence of ADAMTS1, correlating with tumour blockade, supporting its novel role as a modulator of the immune cell response.

N-myc downstream-regulated gene 2 protects blood-brain barrier integrity following cerebral ischemia

Disruption of the blood-brain barrier (BBB) following cerebral ischemia is closely related to the infiltration of peripheral cells into the brain, progression of lesion formation, and clinical exacerbation. However, the mechanism that regulates BBB integrity, especially after permanent ischemia, remains unclear. Here, we present evidence that astrocytic N-myc downstream-regulated gene 2 (NDRG2), a differentiation- and stress-associated molecule, may function as a modulator of BBB permeability following ischemic stroke, using a mouse model of permanent cerebral ischemia. Immunohistological analysis showed that the expression of NDRG2 increases dominantly in astrocytes following permanent middle cerebral artery occlusion (MCAO). Genetic deletion of Ndrg2 exhibited enhanced levels of infarct volume and accumulation of immune cells into the ipsilateral brain hemisphere following ischemia. Extravasation of serum proteins including fibrinogen and immunoglobulin, after MCAO, was enhanced at the ischemic core and perivascular region of the peri-infarct area in the ipsilateral cortex of Ndrg2-deficient mice. Furthermore, the expression of matrix metalloproteinases (MMPs) after MCAO markedly increased in Ndrg2^-/- mice. In culture, expression and secretion of MMP-3 was increased in Ndrg2^-/- astrocytes, and this increase was reversed by adenovirus-mediated re-expression of NDRG2. These findings suggest that NDRG2, expressed in astrocytes, may play a critical role in the regulation of BBB permeability and immune cell infiltration through the modulation of MMP expression following cerebral ischemia.

Triple-Gene Therapy for Stroke: A Proof-of-Concept in Vivo Study in Rats

Natural brain repair after stroke is extremely limited, and current therapeutic options are even more scarce with no clinical break-through in sight. Despite restricted regeneration in the central nervous system, we have previously proved that human umbilical cord blood mono-nuclear cells (UCB-MC) transduced with adenoviral vectors carrying genes encoding vascular endothelial growth factor (VEGF), glial cell-derived neurotrophic factor (GDNF), and neural cell adhesion molecule (NCAM) successfully rescued neurons in amyotrophic lateral sclerosis and spinal cord injury. This proof-of-principle project was aimed at evaluating the beneficial effects of the same triple-gene approach in stroke. Rats subjected to distal occlusion of the middle cerebral artery were treated intrathecally with a combination of these genes either directly or using our cell-based (UCB-MC) approach. Various techniques and markers were employed to evaluate brain injury and subsequent recovery after treatment. Brain repair was most prominent when therapeutic genes were delivered via adenoviral vector- or UCB-MC-mediated approach. Remodeling of brain cortex in the stroke area was confirmed by reduction of infarct volume and attenuated neural cell death, depletion of astrocytes and microglial cells, and increase in the number of oligodendroglial cells and synaptic proteins expression. These results imply that intrathecal injection of genetically engineered UCB-MC over-expressing therapeutic molecules (VEGF, GDNF, and NCAM) following cerebral blood vessel occlusion might represent a novel avenue for future research into treating stroke.

DHCR24 exerts neuroprotection upon inflammation-induced neuronal death

BACKGROUND

DHCR24, involved in the de novo synthesis of cholesterol and protection of neuronal cells against different stress conditions, has been shown to be selectively downregulated in neurons of the affected brain areas in Alzheimer's disease.

METHODS

Here, we investigated whether the overexpression of DHCR24 protects neurons against inflammation-induced neuronal death using co-cultures of mouse embryonic primary cortical neurons and BV2 microglial cells upon acute neuroinflammation. Moreover, the effects of DHCR24 overexpression on dendritic spine density and morphology in cultured mature mouse hippocampal neurons and on the outcome measures of ischemia-induced brain damage in vivo in mice were assessed.

RESULTS

Overexpression of DHCR24 reduced the loss of neurons under inflammation elicited by LPS and IFN-γ treatment in co-cultures of mouse neurons and BV2 microglial cells but did not affect the production of neuroinflammatory mediators, total cellular cholesterol levels, or the activity of proteins linked with neuroprotective signaling. Conversely, the levels of post-synaptic cell adhesion protein neuroligin-1 were significantly increased upon the overexpression of DHCR24 in basal growth conditions. Augmentation of DHCR24 also increased the total number of dendritic spines and the proportion of mushroom spines in mature mouse hippocampal neurons. In vivo, overexpression of DHCR24 in striatum reduced the lesion size measured by MRI in a mouse model of transient focal ischemia.

CONCLUSIONS

These results suggest that the augmentation of DHCR24 levels provides neuroprotection in acute stress conditions, which lead to neuronal loss in vitro and in vivo.

ADAMTS-4 in oligodendrocytes contributes to myelination with an impact on motor function

Myelination is a late developmental process regulated by a set of inhibitory and stimulatory factors, including extracellular matrix components. Accordingly, chondroitin sulfate proteoglycans (CSPGs) act as negative regulators of myelination processes. A disintegrin and metalloproteinase with thrombospondin motifs type 4 (ADAMTS-4) is an extracellular protease capable of degrading CSPGs. Although exogenous ADAMTS-4 has been proven to be beneficial in several models of central nervous system (CNS) injuries, the physiological functions of endogenous ADAMTS-4 remain poorly understood. We first used Adamts4/LacZ reporter mice to reveal that ADAMTS-4 is strongly expressed in the CNS, especially in the white matter, with a cellular profile restricted to mature oligodendrocytes. Interestingly, we evidenced an abnormal myelination in Adamts4^-/- mice, characterized by a higher diameter of myelinated axons with a shifting g-ratio. Accordingly, lack of ADAMTS-4 is accompanied by motor deficits and disturbed nervous electrical activity. In conclusion, we demonstrate that ADAMTS-4 is a new marker of mature oligodendrocytes contributing to the myelination processes and thus to the control of motor capacities.

Molecular Targets for PET Imaging of Activated Microglia: The Current Situation and Future Expectations

Microglia, as cellular mediators of neuroinflammation, are implicated in the pathogenesis of a wide range of neurodegenerative diseases. Positron emission tomography (PET) imaging of microglia has matured over the last 20 years, through the development of radiopharmaceuticals targeting several molecular biomarkers of microglial activation and, among these, mainly the translocator protein-18 kDa (TSPO). Nevertheless, current limitations of TSPO as a PET microglial biomarker exist, such as low brain density, even in a neurodegenerative setting, expression by other cells than the microglia (astrocytes, peripheral macrophages in the case of blood brain barrier breakdown), genetic polymorphism, inducing a variation for most of TSPO PET radiopharmaceuticals’ binding affinity, or similar expression in activated microglia regardless of its polarization (pro- or anti-inflammatory state), and these limitations narrow its potential interest. We overview alternative molecular targets, for which dedicated radiopharmaceuticals have been proposed, including receptors (purinergic receptors P2X7, cannabinoid receptors, α7 and α4β2 nicotinic acetylcholine receptors, adenosine 2A receptor, folate receptor β) and enzymes (cyclooxygenase, nitric oxide synthase, matrix metalloproteinase, β-glucuronidase, and enzymes of the kynurenine pathway), with a particular focus on their respective contribution for the understanding of microglial involvement in neurodegenerative diseases. We discuss opportunities for these potential molecular targets for PET imaging regarding their selectivity for microglia expression and polarization, in relation to the mechanisms by which microglia actively participate in both toxic and neuroprotective actions in brain diseases, and then take into account current clinicians’ expectations.

Lack of collagen XV is protective after ischemic stroke in mice

Collagens are key structural components of basement membranes, providing a scaffold for other components or adhering cells. Collagens and collagen-derived active fragments contribute to biological activities such as cell growth, differentiation and migration. Here, we report that collagen XV knock-out (ColXV KO) mice are resistant to experimental ischemic stroke. Interestingly, the infarcts of ColXV KO mice were as small as those of wild-type (WT) mice thrombolysed with recombinant tissue plasminogen activator (rtPA), the actual treatment for ischemic stroke. Importantly, there were no differences in the architecture of cerebrovascular anatomy between WT and ColXV KO mice. We found a twofold increase of the most potent pro-angiogenic factor, type A vascular growth endothelial factor (VEGF-A) in the ipsilateral cortex of rtPA-treated ischemic WT mice compared with untreated ischemic and sham-operated counterparts. A similar increase of VEGF-A was also found in both rtPA and untreated ischemic ColXV KO mice compared with sham ColXV KO mice. Finally, we evidenced that the levels of ColXV were increased in the plasma of WT mice treated with rtPA compared with untreated ischemic counterparts. Altogether, this study indicates that the lack ColXV is protective after stroke and that the degradation of endothelial ColXV may contribute to the beneficial effect of rtPA after ischemic stroke. The neuroprotection observed in ColXV KO mice may be attributed to the increased VEGF-A production following stroke in the ischemic territory.

The extracellular matrix in cancer progression: Role of hyalectan proteoglycans and ADAMTS enzymes

Remodelling of the extracellular matrix (ECM) has emerged as a key factor in cancer progression. Proteoglycans, including versican and other hyalectans, represent major structural elements of the ECM where they interact with other important molecules, including the glycosaminoglycan hyaluronan and the CD44 cell surface receptor. The hyalectan proteoglycans are regulated through cleavage by the proteolytic actions of A Disintegrin-like And Metalloproteinase domain with Thrombospondin-1 motif (ADAMTS) family members. Alteration in the balance between hyalectan proteoglycans and ADAMTS enzymes has been proposed to be a crucial factor in cancer progression either in a positive or negative manner depending on the context. Further complexity arises due to the formation of bioactive cleavage products, such as versikine, which may also play a role, and non-enzymatic functions for ADAMTS proteins. This research is providing fresh insights into cancer biology and opportunities for the development of new diagnostic and treatment strategies.