Galectin-1-secreting neural stem cells elicit long-term neuroprotection against ischemic brain injury

A dispensable role of oligodendrocyte-derived laminin-α5 in brain homeostasis and intracerebral hemorrhage

Laminin, a major component of the basal lamina in the CNS, is also expressed in oligodendrocytes (OLs). However, the function of OL-derived laminin remains largely unknown. Here, we performed loss-of-function studies using two OL-specific laminin-α5 conditional knockout mouse lines. Both mutants were grossly normal and displayed intact blood-brain barrier (BBB) integrity. In a mouse model of intracerebral hemorrhage (ICH), control mice and both mutants exhibited comparable hematoma size and neurological dysfunction. In addition, similar levels of hemoglobin and IgG leakage were detected in the mutant brains compared to the controls, indicating comparable BBB damage. Consistent with this finding, subsequent studies revealed no differences in tight junction protein (TJP) and caveolin-1 expression among control and knockout mice, suggesting that neither paracellular nor transcellular mechanism was affected in the mutants. Furthermore, compared to the controls, both mutant lines showed comparable oligodendrocyte number, oligodendrocyte proliferation rate, MBP/MAG levels, and SMI-32 expression, highlighting a minimal role of OL-derived laminin-α5 in OL biology. Together, these findings highlight a dispensable role of OL-derived laminin-α5 in both brain homeostasis and ICH pathogenesis.

Time-dependent dual effect of microglia in ischemic stroke

Stroke, the third leading cause of death and disability worldwide, is classified into ischemic or hemorrhagic, in which approximately 85% of strokes are ischemic. Ischemic stroke occurs as a result of arterial occlusion due to embolus or thrombus, with ischemia in the perfusion territory supplied by the occluded artery. The traditional concept that ischemic stroke is solely a vascular occlusion disorder has been expanded to include the dynamic interaction between microglia, astrocytes, neurons, vascular cells, and matrix components forming the "neurovascular unit." Acute ischemic stroke triggers a wide spectrum of neurovascular disturbances, glial activation, and secondary neuroinflammation that promotes further injury, ultimately resulting in neuronal death. Microglia, as the resident macrophages in the central nervous system, is one of the first responders to ischemic injury and plays a significant role in post-ischemic neuroinflammation. In this review, we reviewed the mechanisms of microglia in multiple stages of post-ischemic neuroinflammation development, including acute, sub-acute and chronic phases of stroke. A comprehensive understanding of the dynamic variation and the time-dependent role of microglia in post-stroke neuroinflammation could aid in the search for more effective therapeutics and diagnostic strategies for ischemic stroke.

Regulatory T lymphocytes as a therapy for ischemic stroke

Unrestrained excessive inflammatory responses exacerbate ischemic brain injury and impede post-stroke brain recovery. CD4+CD25+Foxp3+ regulatory T (Treg) cells play important immunosuppressive roles to curtail inflammatory responses and regain immune homeostasis after stroke. Accumulating evidence confirms that Treg cells are neuroprotective at the acute stage after stroke and promote brain repair at the chronic phases. The beneficial effects of Treg cells are mediated by diverse mechanisms involving cell-cell interactions and soluble factor release. Multiple types of cells, including both immune cells and non-immune CNS cells, have been identified to be cellular targets of Treg cells. In this review, we summarize recent findings regarding the function of Treg cells in ischemic stroke and the underlying cellular and molecular mechanisms. The protective and reparative properties of Treg cells endorse them as good candidates for immune therapy. Strategies that boost the numbers and functions of Treg cells have been actively developing in the fields of transplantation and autoimmune diseases. We discuss the approaches for Treg cell expansion that have been tested in stroke models. The application of these approaches to stroke patients may bring new hope for stroke treatments.

Intracerebral Hemorrhage Models and Behavioral Tests in Rodents

Intracerebral hemorrhage (ICH) is one of the common types of stroke, which can cause neurological dysfunction. In preclinical ICH studies, researchers often established rodent models by donor/autologous whole blood or a collagenase injection. White matter injury (WMI) can result from primary and secondary injuries after ICH. WMI can lead to short- and long-term neurological impairment, and functional recovery can assess the effect of drug therapy after ICH. Therefore, researchers have devised various behavioral tests to assess dysfunction. This review compares the two ICH modeling methods in rodents and summarizes the pathological mechanisms underlying dysfunction after ICH. We also summarize the functions and characteristics of various behavioral methods, including sensation, motion, emotion, and cognition, to assist researchers in selecting the appropriate tests for preclinical ICH research.

Dying transplanted neural stem cells mediate survival bystander effects in the injured brain

Neural stem and progenitor cell (NSPC) transplants provide neuroprotection in models of acute brain injury, but the underlying mechanisms are not fully understood. Here, we provide evidence that caspase-dependent apoptotic cell death of NSPCs is required for sending survival signals to the injured brain. The secretome of dying NSPCs contains heat-stable proteins, which protect neurons against glutamate-induced toxicity and trophic factor withdrawal in vitro, and from ischemic brain damage in vivo. Our findings support a new concept suggesting a bystander effect of apoptotic NSPCs, which actively promote neuronal survival through the release of a protective "farewell" secretome. Similar protective effects by the secretome of apoptotic NSPC were also confirmed in human neural progenitor cells and neural stem cells but not in mouse embryonic fibroblasts (MEF) or human dopaminergic neurons, suggesting that the observed effects are cell type specific and exist for neural progenitor/stem cells across species.

A Preclinical Systematic Review and Meta-Analysis of Behavior Testing in Mice Models of Ischemic Stroke

Stroke remains one of the most important causes of death and disability. Preclinical research is a powerful tool for understanding the molecular and cellular response to stroke. However, a lack of standardization in animal evaluation does not always ensure reproducible results. In the present study, we wanted to identify the best strategy for evaluating animal behavior post-experimental stroke. As such, a meta-analysis was made, evaluating behavioral tests done on male C57BL/6 mice subjected to stroke or sham surgery. Overall, fifty-six studies were included. Our results suggest that different types of tests should be used depending on the post-stroke period one needs to analyze. In the hyper-acute, post-stroke period, the best quantifier will be animal examination scoring, as it is a fast and inexpensive way to identify differences between groups. When evaluating stoke mice in the acute phase, a mix of animal examination and motor tests that focus on movement asymmetry (foot-fault and cylinder testing) seem to have the best chance of picking up differences between groups. Complex tasks (the rotarod test and Morris water maze) should be used within the chronic phase to evaluate differences between the late-subacute and chronic phases.

Neuroprotective Effect of Exogenous Galectin-1 in Status Epilepticus

Intrahippocampal pilocarpine microinjection (H-PILO) induces status epilepticus (SE) that can lead to spontaneous recurrent seizures (SRS) and neurodegeneration in rodents. Studies using animal models have indicated that lectins mediate a variety of biological activities with neuronal benefits, especially galectin-1 (GAL-1), which has been identified as an effective neuroprotective compound. GAL-1 is associated with the regulation of cell adhesion, proliferation, programmed cell death, and immune responses, as well as attenuating neuroinflammation. Here, we administrated GAL-1 to Wistar rats and evaluated the severity of the SE, neurodegenerative and inflammatory patterns in the hippocampal formation. Administration of GAL-1 caused a reduction in the number of class 2 and 4 seizures, indicating a decrease in seizure severity. Furthermore, we observed a reduction in inflammation and neurodegeneration 24 h and 15 days after SE. Overall, these results suggest that GAL-1 has a neuroprotective effect in the early stage of epileptogenesis and provides new insights into the roles of exogenous lectins in temporal lobe epilepsy (TLE).

Overexpression of IGF-1 During Early Development Expands the Number of Mammary Stem Cells and Primes them for Transformation

Insulin-like growth factor I (IGF-1) has been implicated in breast cancer due to its mitogenic and anti-apoptotic effects. Despite substantial research on the role of IGF-1 in tumor progression, the relationship of IGF-1 to tissue stem cells, particularly in mammary tissue, and the resulting tumor susceptibility has not been elucidated. Previous studies with the BK5.IGF-1 transgenic (Tg) mouse model reveals that IGF-1 does not act as a classical, post-carcinogen tumor promoter in the mammary gland. Pre-pubertal Tg mammary glands display increased numbers and enlarged sizes of terminal end buds, a niche for mammary stem cells (MaSCs). Here we show that MaSCs from both wild type (WT) and Tg mice expressed IGF-1R and that overexpression of Tg IGF-1 increased numbers of MaSCs by undergoing symmetric division, resulting in an expansion of the MaSC and luminal progenitor (LP) compartments in pre-pubertal female mice. This expansion was maintained post-pubertally and validated by mammosphere assays in vitro and transplantation assays in vivo. The addition of recombinant IGF-1 promoted, and IGF-1R downstream inhibitors decreased mammosphere formation. Single-cell transcriptomic profiles generated from two related platforms reveal that IGF-1 stimulated quiescent MaSCs to enter the cell cycle and increased their expression of genes involved in proliferation, plasticity, tumorigenesis, invasion, and metastasis. This study identifies a novel, pro-tumorigenic mechanism, where IGF-1 increases the number of transformation-susceptible carcinogen targets during the early stages of mammary tissue development, and “primes” their gene expression profiles for transformation.

Neuroinflammation as a Key Driver of Secondary Neurodegeneration Following Stroke?

Ischaemic stroke involves the rapid onset of focal neurological dysfunction, most commonly due to an arterial blockage in a specific region of the brain. Stroke is a leading cause of death and common cause of disability, with over 17 million people worldwide suffering from a stroke each year. It is now well-documented that neuroinflammation and immune mediators play a key role in acute and long-term neuronal tissue damage and healing, not only in the infarct core but also in distal regions. Importantly, in these distal regions, termed sites of secondary neurodegeneration (SND), spikes in neuroinflammation may be seen sometime after the initial stroke onset, but prior to the presence of the neuronal tissue damage within these regions. However, it is key to acknowledge that, despite the mounting information describing neuroinflammation following ischaemic stroke, the exact mechanisms whereby inflammatory cells and their mediators drive stroke-induced neuroinflammation are still not fully understood. As a result, current anti-inflammatory treatments have failed to show efficacy in clinical trials. In this review we discuss the complexities of post-stroke neuroinflammation, specifically how it affects neuronal tissue and post-stroke outcome acutely, chronically, and in sites of SND. We then discuss current and previously assessed anti-inflammatory therapies, with a particular focus on how failed anti-inflammatories may be repurposed to target SND-associated neuroinflammation.

Gene Therapy Approach with an Emphasis on Growth Factors: Theoretical and Clinical Outcomes in Neurodegenerative Diseases

The etiology of many neurological diseases affecting the central nervous system (CNS) is unknown and still needs more effective and specific therapeutic approaches. Gene therapy has a promising future in treating neurodegenerative disorders by correcting the genetic defects or by therapeutic protein delivery and is now an attraction for neurologists to treat brain disorders, like Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, spinal muscular atrophy, spinocerebellar ataxia, epilepsy, Huntington’s disease, stroke, and spinal cord injury. Gene therapy allows the transgene induction, with a unique expression in cells’ substrate. This article mainly focuses on the delivering modes of genetic materials in the CNS, which includes viral and non-viral vectors and their application in gene therapy. Despite the many clinical trials conducted so far, data have shown disappointing outcomes. The efforts done to improve outcomes, efficacy, and safety in the identification of targets in various neurological disorders are also discussed here. Adapting gene therapy as a new therapeutic approach for treating neurological disorders seems to be promising, with early detection and delivery of therapy before the neuron is lost, helping a lot the development of new therapeutic options to translate to the clinic.

Carbonyl Reductase 1 Attenuates Ischemic Brain Injury by Reducing Oxidative Stress and Neuroinflammation

Oxidative stress and neuroinflammatory response after the ischemic injury are important pathophysiologic mechanisms that cause brain tissue loss and neurological deficit. This study aims to observe the expression and role of carbonyl reductase 1 (CBR1), an NADPH-dependent oxidoreductase with specificity for carbonyl compounds such as 4-hydroxynonenal (4-HNE), in the brain after ischemic injury and to investigate the influence of CBR1 on ischemia-induced neuroinflammation. CBR1 expresses in the neurons, astrocyte, and microglia in the normal brain. The expression of CBR1 decreased in the ischemic regions following cerebral ischemia, and also reduced in primary neurons after OGD (oxygen-glucose deprivation); however, the expression of CBR1 significantly increased in microglia in the ischemic penumbra. Furthermore, TAT-CBR1 fusion protein played neuroprotective effects in reducing the infarct volume and improving neurological outcomes after ischemic injury. Mechanistically, CBR1 decreased the levels of 4-HNE in the brain after stroke; it also modulated microglial polarization toward the M2 phenotype, which was well-known to confer neuroprotection after ischemic injury. Our results demonstrate that CBR1 provides neuroprotection against ischemic injury by reducing oxidative stress and neuroinflammation, making a promising agent for cerebral ischemia treatment.

Stem Cell-Based Therapy for Experimental Ischemic Stroke: A Preclinical Systematic Review

Stem cell transplantation offers promise in the treatment of ischemic stroke. Here we utilized systematic review, meta-analysis, and meta-regression to study the biological effect of stem cell treatments in animal models of ischemic stroke. A total of 98 eligible publications were included by searching PubMed, EMBASE, and Web of Science from inception to August 1, 2020. There are about 141 comparisons, involving 5,200 animals, that examined the effect of stem cell transplantation on neurological function and infarct volume as primary outcome measures in animal models for stroke. Stem cell-based therapy can improve both neurological function (effect size, −3.37; 95% confidence interval, −3.83 to −2.90) and infarct volume (effect size, −11.37; 95% confidence interval, −12.89 to −9.85) compared with controls. These results suggest that stem cell therapy could improve neurological function deficits and infarct volume, exerting potential neuroprotective effect for experimental ischemic stroke, but further clinical studies are still needed.

Receptors, Channel Proteins, and Enzymes Involved in Microglia-mediated Neuroinflammation and Treatments by Targeting Microglia in Ischemic Stroke

Stroke is the largest contributor to global neurological disability-adjusted life-years, posing a huge economic and social burden to the world. Though pharmacological recanalization with recombinant tissue plasminogen activator and mechanical thrombectomy have greatly improved the prognosis of patients with ischemic stroke, clinically, there is still no effective treatment for the secondary injury caused by cerebral ischemia. In recent years, more and more evidences show that neuroinflammation plays a pivotal role in the pathogenesis and progression of ischemic cerebral injury. Microglia are brain resident innate immune cells and act the role peripheral macrophages. They play critical roles in mediating neuroinflammation after ischemic stroke. Microglia-mediated neuroinflammation is not an isolated process and has complex relationships with other pathophysiological processes as oxidative/nitrative stress, excitotoxicity, necrosis, apoptosis, pyroptosis, autophagy, and adaptive immune response. Upon activation, microglia differentially express various receptors, channel proteins, and enzymes involved in promoting or inhibiting the inflammatory processes, making them the targets of intervention for ischemic stroke. To inhibit microglia-related neuroinflammation and promote neurological recovery after ischemic stroke, numerous biochemical agents, cellular therapies, and physical methods have been demonstrated to have therapeutic potentials. Though accumulating experimental evidences have demonstrated that targeting microglia is a promising approach in the treatment of ischemic stroke, the clinical progress is slow. Till now, no clinical study could provide convincing evidence that any biochemical or physical therapies could exert neuroprotective effect by specifically targeting microglia following ischemic stroke.

Low-Dose IL-2 Treatment Affords Protection against Subarachnoid Hemorrhage Injury by Expanding Peripheral Regulatory T Cells

Subarachnoid hemorrhage (SAH) is considered a devastating disease, leaving survivors with lifelong neurological impairment. With increased knowledge that regulatory T cells (Tregs) provide protection against stroke, novel agents which could expand Treg populations have been assessed in terms of the potential clinical neuroprotection effect. Using a rat SAH model, we investigated the number variation of Tregs induced by SAH and the protective effect of low-dose interleukin-2 (IL-2) treatment on the SAH model. We observed that the number of peripheral Tregs significantly decreased soon after SAH, accompanying with reactivity recovery after 3 days. Our results also revealed that low-dose IL-2 treatment not only elevated Tregs numbers but significantly reduced neuronal injury and improved neurological functions up to 21 days (d) after SAH. Furthermore, compared with PBS-treatment group, cerebral proinflammatory factors and peripheral neutrophils were significantly suppressed by low-dose IL-2 after SAH. Therefore, the results suggest that low-dose IL-2 treatment is a novel and clinically feasible immunotherapy to improve long-term outcomes after SAH, perhaps via up-regulating Treg population to suppress neuroinflammation induced by SAH.

Behavioral, axonal, and proteomic alterations following repeated mild traumatic brain injury: Novel insights using a clinically relevant rat model

A history of mild traumatic brain injury (mTBI) is linked to a number of chronic neurological conditions, however there is still much unknown about the underlying mechanisms. To provide new insights, this study used a clinically relevant model of repeated mTBI in rats to characterize the acute and chronic neuropathological and neurobehavioral consequences of these injuries. Rats were given four sham-injuries or four mTBIs and allocated to 7-day or 3.5-months post-injury recovery groups. Behavioral analysis assessed sensorimotor function, locomotion, anxiety, and spatial memory. Neuropathological analysis included serum quantification of neurofilament light (NfL), mass spectrometry of the hippocampal proteome, and ex vivo magnetic resonance imaging (MRI). Repeated mTBI rats had evidence of acute cognitive deficits and prolonged sensorimotor impairments. Serum NfL was elevated at 7 days post injury, with levels correlating with sensorimotor deficits; however, no NfL differences were observed at 3.5 months. Several hippocampal proteins were altered by repeated mTBI, including those associated with energy metabolism, neuroinflammation, and impaired neurogenic capacity. Diffusion MRI analysis at 3.5 months found widespread reductions in white matter integrity. Taken together, these findings provide novel insights into the nature and progression of repeated mTBI neuropathology that may underlie lingering or chronic neurobehavioral deficits.

Synthesis of tricyclic carbohydrate–benzene hybrids as selective inhibitors of galectin-1 and galectin-8 N-terminal domains

As the galactoside binding family of galectin proteins is involved in many physiological and pathological processes, the inhibitors of these proteins are considered to be of significant interest in the treatment of diseases such as cancer and fibrosis. Herein, fused tricyclic carbohydrate–benzene hybrid core structures are reported to be the selective inhibitors of galectin-1 and the N-terminal domain of galectin-8 by a competitive fluorescence polarization assay. The key intermediates mono- or diiodo tricyclic carbohydrate–benzene hybrids were synthesized from protected 2-bromo-3-O-propargyl-d-galactose via a domino reaction and subsequently utilized for further derivatization by Stille couplings to achieve derivatives carrying substituents at C10 and/or C11. Several compounds showed affinity for the galectin-1 and galectin-8 N-terminal (8N) domains; however, weak or even no binding was observed for galectin-3. Monosubstituted derivatives at C10 or C11 exhibited better affinity for galectin-8N than di-substituted derivatives at C10 or C11. Especially, a benzyl substituent or p-fluorobenzyl substituent at C11 displayed affinity and selectivity for galectin-1 and galectin-8N over galectin-3. This suggests that tricyclic carbohydrate–benzene hybrids are promising scaffolds for the development of selective galectin-1 and galectin-8N inhibitors.

Fused tricyclic carbohydrate–benzene hybrids carrying substituents at C10 and/or C11 were designed, synthesized and evaluated as inhibitors for galectin-1 and the N-terminal domain of galectin-8.

Ischemic preconditioning provides long-lasting neuroprotection against ischemic stroke: The role of Nrf2

BACKGROUND AND PURPOSE

A major gap in the field of ischemic preconditioning (IPC) is whether or not long-lasting neuroprotection can be achieved. Moreover, the specific mechanisms underlying IPC and how they can be translated into the clinic remain uncertain. To fill these gaps, we tested the hypothesis that IPC exerts long-lasting structural and functional neuroprotection against ischemic stroke through the master gatekeeper of antioxidant defenses, nuclear factor erythroid 2-related factor 2 (Nrf2). We also tested whether the brain could be pharmaceutically preconditioned with a potent and blood-brain barrier-permeable Nrf2 activator, 2-cyano-3,12-dioxo-oleana-1,9(11)-dien-28-trifluoethyl amide (CDDO-TFEA).

METHODS

IPC was induced by transient middle cerebral artery occlusion (MCAO) for 12 min, and ischemic stroke was generated by MCAO for 60 min in wild-type (WT) or Nrf2 knockout (KO) mice. Sensorimotor function, learning/memory skills, and brain tissue loss were measured up to 35 days after stroke. Primary rodent cortical neurons from wildtype (WT) and Nrf2 KO mice were subjected to lethal oxygen-glucose deprivation (OGD) or a brief OGD episode as a preconditioning (PC) stimulus before OGD. Cell viability/death, lipid electrophile generation, and Nrf2 activation were measured. CDDO-TFEA or its vehicle was administered in vivo for three consecutive days before MCAO. Tissue loss and neurological tests were performed 35 days after stroke.

RESULTS

IPC significantly reduced sensorimotor deficits, post-stroke cognitive impairments, and brain tissue loss, 35 days after MCAO in WT mice. These enduring protective effects of IPC were inhibited in Nrf2 KO mice. In neuronal cultures, PC also endowed primary neurons with ischemic tolerance against OGD-induced cell death, an effect that was abolished by loss of Nrf2 expression in KO neurons. PC induced the generation of low levels of lipid electrophiles and led to activation of the Nrf2 pathway. The mechanism underlying IPC may be translatable, as exogenous administration of the Nrf2 activator CDDO-TFEA significantly reduced neurological dysfunction and ischemic brain damage after MCAO.

CONCLUSIONS

IPC provides long-lasting neuroprotection against ischemic brain injury and post-stroke cognitive dysfunction. Nrf2 activation plays a key role in this beneficial outcome and is a promising therapeutic target for the attenuation of ischemic brain injury.

Animal Galectins and Plant Lectins as Tools for Studies in Neurosciences

Lectins are proteins or glycoproteins of non-immunological origin capable of reversibly and specifically binding to glycoconjugates. They exist in free form or associated with cells and are widely distributed in nature, being found in plants, microorganisms, and animals. Due to their characteristics and mainly due to the possibility of reversible binding to glycoconjugates, lectins have stood out as important tools in research involving Neurobiology. These proteins have the ability to modulate molecular targets in the central nervous system (CNS) which may be involved with neuroplasticity, neurobehavioral effects, and neuroprotection. The present report integrates existing information on the activity of animal and plant lectins in different areas of Neuroscience, presenting perspectives to direct new research on lectin function in the CNS, providing alternatives for understanding neurological diseases such as mental disorders, neurodegenerative, and neuro-oncological diseases, and for the development of new drugs, diagnoses and therapies in the field of Neuroscience.

Cylinder Test to Assess Sensory-motor Function in a Mouse Model of Parkinson's Disease

Parkinson's disease is a progressive neurodegenerative movement disorder that happens due to the loss of dopaminergic neurons in the substantia nigra. The deficiency of dopamine in the basal nuclei drives cardinal motor symptoms such as bradykinesia and hypokinesia. The current protocol describes the cylinder test, which is a relatively simple behavioral assessment that evaluates the motor deficits upon unilateral degeneration of the nigrostriatal pathway in experimental models of Parkinson's disease. Since dopamine-depleted mice exhibit the preferential use of the forelimb ipsilateral to the lesion, here researchers perform the cylinder test to investigate the therapeutic effects of antiparkinsonian treatments on the performance of the contralateral (injured) limb.

[α-Klotho protein in neurodegenerative and mental diseases]

The review aims to attract attention of psychiatrists and neurologists to a role of α-Klotho protein in biochemical mechanisms that counteract pathogenic processes of neurodegenerative and psychiatric diseases and to possible therapeutic potential of the protein. Basing on the analysis of contemporary literature, the authors summarized the results of model experiments and a few clinical trials (in psychiatry and neurology) indicating the role of α-Klotho protein in the brain processes of neurogenesis, dendrite growth, myelination (oligodendroglia differentiation and activity), regulation of antioxidant system, and synthesis of glutamate neurotransmitter system components, regulation of the activity and synthesis of ion channel protein components and membrane transporters, synaptic plasticity. It is concluded that α-Klotho protein can be used for therapeutic purposes in diseases associated with pathological brain aging, and/or in diseases associated with insufficient synthesis of this protein.

Protective effects of sulforaphane in experimental vascular cognitive impairment: Contribution of the Nrf2 pathway

The major pathophysiological process of vascular cognitive impairment (VCI) is chronic cerebral ischemia, which causes disintegration of the blood-brain barrier (BBB), neuronal death, and white matter injury. This study aims to test whether sulforaphane (Sfn), a natural activator of nuclear factor erythroid 2-related factor 2 (Nrf2), reduces the chronic ischemic injury and cognitive dysfunction after VCI. Experimental VCI was induced in rats by permanent occlusion of both common carotid arteries for six weeks. This procedure caused notable neuronal death in the cortex and hippocampal CA1, myelin loss in the corpus callosum and hippocampal fimbria, accumulation of myelin debris in the corpus callosum, and remarkable cognitive impairment. Sfn treatment alleviated these ischemic injuries and the cognitive dysfunction. Sfn-mediated neuroprotection was associated with enhanced activation of Nrf2 and upregulation of heme oxygenase 1. Sfn also reduced neuronal and endothelial death and maintained the integrity of BBB after oxygen-glucose deprivation in vitro in an Nrf2 dependent manner. Furthermore, Nrf2 knockdown in endothelial cells decreased claudin-5 protein expression with downregulated claudin-5 promoter activity, suggesting that claudin-5 might be a target gene of Nrf2. Our results demonstrate that Sfn provides robust neuroprotection against chronic brain ischemic injury and may be a promising agent for VCI treatment.

The NLRP3 inflammasome is involved in the neuroprotective mechanism of neural stem cells against microglia-mediated toxicity in SH-SY5Y cells via the attenuation of tau hyperphosphorylation and amyloidogenesis

The cognitive impairment caused by Alzheimer's disease (AD) is associated with beta-amyloid (Aβ) and tau proteins, and is accompanied by inflammation. Recently, a novel inflammasome signaling pathway has been uncovered. Inflammasomes are implicated in the execution of inflammatory responses and pyroptotic death leading to neurodegeneration. Thus, the inflammasome signaling pathway could be a potential therapeutic target for AD. Neural stem cells (NSCs) are multipotent cells that can self-renew and differentiate into distinct neural cells. NSC therapy has been considered to be a promising therapeutic approach in protecting the central nervous system and restoring it following damage. However, the mechanisms involved remain unclear. The aims of this study were to investigate the protective effects of NE4C neural stem cells against microglia-mediated neurotoxicity and to explore molecular mechanisms mediating their actions. NE4C decreased the levels of caspase-1 and IL-1β, and attenuated the level of the NLRP3 inflammasome and its associated protein adapter, apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) in LPS-stimulated BV2 microglial cells, possibly by regulating the phosphorylation of p38α MAPK. The conditioned media obtained from co-culture of LPS-stimulated BV2 and NE4C cells exhibited protective effects on SH-SY5Y cells against microglia-mediated neurotoxicity; this was associated with an attenuation of tau phosphorylation and amyloidogenesis and accompanied by down-regulation of GSK-3β and p38α MAPK signalling pathways. In conclusion, the present study suggested that NSC therapy could be a potential strategy against microglia-mediated neurotoxicity. NSCs regulate NLRP3 activation and IL-1β secretion, which are critical in the initiation of the inflammatory responses, hence preventing the release of neurotoxic pro-inflammatory factors by microglia. This eventually reduces tau hyperphosphylation and amyloidogenesis, possibly through the regulation of GSK-3β and p38α MAPK signalling pathways, and thus protects SH-SY5Y cells against microglia-mediated neurotoxicity.

Galectin-1 as an Emerging Mediator of Cardiovascular Inflammation: Mechanisms and Therapeutic Opportunities

Galectin-1 (Gal-1), an evolutionarily conserved β-galactoside-binding lectin, controls immune cell homeostasis and tempers acute and chronic inflammation by blunting proinflammatory cytokine synthesis, engaging T-cell apoptotic programs, promoting expansion of T regulatory (Treg) cells, and deactivating antigen-presenting cells. In addition, this lectin promotes angiogenesis by co-opting the vascular endothelial growth factor receptor (VEGFR) 2 signaling pathway. Since a coordinated network of immunomodulatory and proangiogenic mediators controls cardiac homeostasis, this lectin has been proposed to play a key hierarchical role in cardiac pathophysiology via glycan-dependent regulation of inflammatory responses. Here, we discuss the emerging roles of Gal-1 in cardiovascular diseases including acute myocardial infarction, heart failure, Chagas cardiomyopathy, pulmonary hypertension, and ischemic stroke, highlighting underlying anti-inflammatory mechanisms and therapeutic opportunities. Whereas Gal-1 administration emerges as a potential novel treatment option in acute myocardial infarction and ischemic stroke, Gal-1 blockade may contribute to attenuate pulmonary arterial hypertension.

Brain-selective mild hypothermia promotes long-term white matter integrity after ischemic stroke in mice

INTRODUCTION

The neuroprotective effects of hypothermia in acute ischemic stroke are well documented. However, the mechanisms involved in the effects remain to be clearly elucidated and the role of hypothermia on long-term white matter integrity after acute ischemic stroke has yet to be investigated.

AIMS

To investigate the role of mild focal hypothermia on long-term white matter (WM) integrity after transient cerebral ischemia.

RESULTS

Mild focal hypothermia treatment immediately after ischemic stroke significantly promotes WM integrity 28 days after the occlusion of the middle cerebral artery (MCAO) in mice. Higher integrity of white matter, lower activation of total microglia, less infarct volume, and better neurobehavioral function were detected in hypothermia-treated mice compared to normothermia-treated mice. Furthermore, we found that hypothermia could decrease detrimental M1 phenotype microglia and promote healthy M2 phenotype microglia. In vitro, results also indicated that hypothermia promoted oligodendrocytes differentiation and maturation after oxygen glucose deprivation.

CONCLUSION

Hypothermia promotes long-term WM integrity and inhibits neuroinflammation in a mouse model of ischemic brain injury.

The Expression of Immunomodulation-Related Cytokines and Genes of Adipose- and Bone Marrow-Derived Human Mesenchymal Stromal Cells from Early to Late Passages

BACKGROUND

Mesenchymal stromal cells (MSCs) are multipotent stem cells that can differentiate into several cell types. In addition, many studies have shown that MSCs modulate the immune response. However, little information is currently available regarding the maintenance of immunomodulatory characteristics of MSCs through passages. Therefore, we investigated and compared cytokine and gene expression levels from adipose (AD) and bone marrow (BM)-derived MSCs relevant to immune modulation from early to late passages.

METHODS

MSC immunophenotype, growth characteristics, cytokine expressions, and gene expressions were analyzed.

RESULTS

AD-MSCs and BM-MSCs had similar cell morphologies and surface marker expressions from passage 4 to passage 10. Cytokines secreted by AD-MSCs and BM-MSCs were similar from early to late passages. AD-MSCs and BM-MSCs showed similar immunomodulatory properties in terms of cytokine secretion levels. However, the gene expressions of tumor necrosis factor-stimulated gene (TSG)-6 and human leukocyte antigen (HLA)-G were decreased and gene expressions of galectin-1 and -3 were increased in both AD- and BM-MSCs with repeated passages.

CONCLUSION

Our study showed that the immunophenotype and expression of immunomodulation-related cytokines of AD-MSCs and BM-MSCs immunomodulation through the passages were not significantly different, even though the gene expressions of both MSCs were different.

Selective role of Na+ /H+ exchanger in Cx3cr1+ microglial activation, white matter demyelination, and post-stroke function recovery

Na⁺ /H⁺ exchanger (NHE1) activation is required for multiple microglial functions. We investigated effects of selective deletion of microglial Nhe1 in Cx3cr1-Cre^ER ;Nhe1^f/f mice on neuroinflammation and tissue repair after ischemic stroke. Infarct volume was similar in corn oil or tamoxifen (Tam)-treated mice at 48 hr and 14 days post-stroke. However, the Tam-treated mice showed significantly higher survival rate and faster neurological function recovery during day 1-14 post-stroke. Deletion of microglial Nhe1 prevented the elevation of CD11b⁺ /CD45^low-med microglia in the ischemic hemisphere at day 3 post-stroke, but stimulated expression of Ym1, CD68, TGF-β, IL-10, decreased expression of CD86 and IL-1β, and reduced GFAP⁺ reactive astrocytes. Moreover, at day 14 post-stroke, enhanced white matter myelination was detected in the microglial Nhe1 deleted mice. In comparison, neuronal Nhe1-null mice (the CamKII-Cre^+/- ;Nhe1^f/f mice) showed a significant reduction in both acute and subacute infarct volume, along with increased survival rate and moderate neurological function recovery. However, these neuronal Nhe1-null mice did not exhibit reduced activation of CD11b⁺ /CD45^low-med microglia or CD11b⁺ /CD45^hi macrophages in the ischemic brains, and they exhibited no reductions in white matter lesions. Taken together, this study demonstrated that deletion of microglial and neuronal Nhe1 had differential effects on ischemic brain damage. Microglial NHE1 is involved in pro-inflammatory responses during post-stroke brain tissue repair. In contrast, neuronal NHE1 activation is directly associated with the acute ischemic neuronal injury but not inflammation. Our study reveals that NHE1 protein is a potential therapeutic target critical for differential regulation of ischemic neuronal injury, demyelination and tissue repair.

Stem Cells Engineered During Different Stages of Reprogramming Reveal Varying Therapeutic Efficacies

Stem cells are emerging as promising treatment strategies for several brain disorders and pathologies. In this study, we explored the potential of creating induced pluripotent stem cell-derived neural stem cells (ipNSC) by using either unmodified or gene-modified somatic cells and tested their fate and therapeutic efficacies in vitro and in vivo. We show that cells engineered in somatic state lose transgene-expression during the neural induction process, which is partially restored by histone deacetylase inhibitor treatment whereas cells engineered at the ipNSC state have sustained expression of transgenes. In vivo, bimodal mouse and human ipNSCs engineered to express tumor specific death-receptor ligand and suicide-inducing therapeutic proteins have profound anti-tumor efficacy when encapsulated in synthetic extracellular matrix and transplanted in mouse models of resected-glioblastoma. This study provides insights into using somatic cells for treating CNS disorders and presents a receptor-targeted cancer therapeutic approach for brain tumors. Stem Cells 2018;36:932-942.

Unconventional Protein Secretion in Animal Cells

All eukaryotic cells secrete a range of proteins in a constitutive or regulated manner through the conventional or canonical exocytic/secretory pathway characterized by vesicular traffic from the endoplasmic reticulum, through the Golgi apparatus, and towards the plasma membrane. However, a number of proteins are secreted in an unconventional manner, which are insensitive to inhibitors of conventional exocytosis and use a route that bypasses the Golgi apparatus. These include cytosolic proteins such as fibroblast growth factor 2 (FGF2) and interleukin-1β (IL-1β), and membrane proteins that are known to also traverse to the plasma membrane by a conventional process of exocytosis, such as α integrin and the cystic fibrosis transmembrane conductor (CFTR). Mechanisms underlying unconventional protein secretion (UPS) are actively being analyzed and deciphered, and these range from an unusual form of plasma membrane translocation to vesicular processes involving the generation of exosomes and other extracellular microvesicles. In this chapter, we provide an overview on what is currently known about UPS in animal cells.

Docosahexaenoic acid (DHA) enhances the therapeutic potential of neonatal neural stem cell transplantation post-Traumatic brain injury

Traumatic Brain Injury (TBI) is a major cause of death and disability worldwide with 1.5 million people inflicted yearly. Several neurotherapeutic interventions have been proposed including drug administration as well as cellular therapy involving neural stem cells (NSCs). Among the proposed drugs is docosahexaenoic acid (DHA), a polyunsaturated fatty acid, exhibiting neuroprotective properties. In this study, we utilized an innovative intervention of neonatal NSCs transplantation in combination with DHA injections in order to ameliorate brain damage and promote functional recovery in an experimental model of TBI. Thus, NSCs derived from the subventricular zone of neonatal pups were cultured into neurospheres and transplanted in the cortex of an experimentally controlled cortical impact mouse model of TBI. The effect of NSC transplantation was assessed alone and/or in combination with DHA administration. Motor deficits were evaluated using pole climbing and rotarod tests. Using immunohistochemistry, the effect of transplanted NSCs and DHA treatment was used to assess astrocytic (Glial fibrillary acidic protein, GFAP) and microglial (ionized calcium binding adaptor molecule-1, IBA-1) activity. In addition, we quantified neuroblasts (doublecortin; DCX) and dopaminergic neurons (tyrosine hydroxylase; TH) expression levels. Combined NSC transplantation and DHA injections significantly attenuated TBI-induced motor function deficits (pole climbing test), promoted neurogenesis, coupled with an increase in glial reactivity at the cortical site of injury. In addition, the number of tyrosine hydroxylase positive neurons was found to increase markedly in the ventral tegmental area and substantia nigra in the combination therapy group. Immunoblotting analysis indicated that DHA+NSCs treated animals showed decreased levels of 38kDa GFAP-BDP (breakdown product) and 145kDa αII-spectrin SBDP indicative of attenuated calpain/caspase activation. These data demonstrate that prior treatment with DHA may be a desirable strategy to improve the therapeutic efficacy of NSC transplantation in TBI.

Galectin-1 and galectin-3 expression in equine mesenchymal stromal cells (MSCs), synovial fibroblasts and chondrocytes, and the effect of inflammation on MSC motility

Background

Mesenchymal stromal cells (MSCs) can be used intra-articularly to quell inflammation and promote cartilage healing; however, mechanisms by which MSCs mitigate joint disease remain poorly understood. Galectins, a family of β-galactoside binding proteins, regulate inflammation, adhesion and cell migration in diverse cell types. Galectin-1 and galectin-3 are proposed to be important intra-articular modulators of inflammation in both osteoarthritis and rheumatoid arthritis. Here, we asked whether equine bone marrow-derived MSCs (BMSCs) express higher levels of galectin-1 and -3 relative to synovial fibroblasts and chondrocytes and if an inflammatory environment affects BMSC galectin expression and motility.

Methods

Equine galectin-1 and -3 gene expression was quantified using qRT-PCR in cultured BMSCs, synoviocytes and articular chondrocytes, in addition to synovial membrane and articular cartilage tissues. Galectin gene expression, protein expression, and protein secretion were measured in equine BMSCs following exposure to inflammatory cytokines (IL-1β 5 and 10 ng/mL, TNF-α 25 and 50 ng/mL, or LPS 0.1, 1, 10 and 50 μg/mL). BMSC focal adhesion formation was assessed using confocal microscopy, and BMSC motility was quantified in the presence of inflammatory cytokines (IL-1β or TNF-α) and the pan-galectin inhibitor β-lactose (100 and 200 mM).

Results

Equine BMSCs expressed 3-fold higher galectin-1 mRNA levels as compared to cultured synovial fibroblasts (p = 0.0005) and 30-fold higher galectin-1 (p < 0.0001) relative to cultured chondrocytes. BMSC galectin-1 mRNA expression was significantly increased as compared to carpal synovial membrane and articular cartilage tissues (p < 0.0001). IL-1β and TNF-α treatments decreased BMSC galectin gene expression and impaired BMSC motility in dose-dependent fashion but did not alter galectin protein expression. β-lactose abrogated BMSC focal adhesion formation and inhibited BMSC motility.

Conclusions

Equine BMSCs constitutively express high levels of galectin-1 mRNA relative to other articular cell types, suggesting a possible mechanism for their intra-articular immunomodulatory properties. BMSC galectin expression and motility are impaired in an inflammatory environment, which may limit tissue repair properties following intra-articular administration. β-lactose-mediated galectin inhibition also impaired BMSC adhesion and motility. Further investigation into the effects of joint inflammation on BMSC function and the potential therapeutic effects of BMSC galectin expression in OA is warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0691-2) contains supplementary material, which is available to authorized users.

The relevance of α-KLOTHO to the central nervous system: Some key questions

α-Klotho is well described as an anti-aging protein, with critical roles in kidney function as a transmembrane co-receptor for FGF23, and as a soluble factor in serum. α-Klotho is also expressed in the choroid plexus, where it is released into the cerebrospinal fluid. Nonetheless, α-Klotho is also expressed in the brain parenchyma. Accumulating evidence indicates that this pool of α-Klotho, which we define as brain α-Klotho, may play important roles as a neuroprotective factor and in promoting myelination, thereby supporting healthy brain aging. Here we summarize what is known about brain α-Klotho before focusing on the outstanding scientific questions related to its function. We believe there is a need for in vitro studies designed to distinguish between brain α-Klotho and other pools of α-Klotho, and for a greater understanding of the basic function of soluble α-Klotho. The mechanism by which the human KL-VS variant affects cognition also requires further elucidation. To help address these questions we suggest some experimental approaches that other laboratories might consider. In short, we hope to stimulate fresh ideas and encourage new research approaches that will allow the importance of α-Klotho for the aging brain to become clear.

Bone Marrow Mesenchymal Stem Cells Inhibit the Function of Dendritic Cells by Secreting Galectin-1

This study aimed to investigate whether bone marrow-derived mesenchymal stem cells (BM-MSCs) can inhibit function of dendritic cells (DCs) by secreting Galectin-1 (Gal-1). BM-MSCs have been shown to inhibit the maturation and function of DCs, further inhibiting the activation and proliferation of T cells. However, the detailed mechanism remains unknown. In this current study, MSCs and DCs derived from mouse bone marrow were cocultured using Transwell culture plates under different in vitro conditions. The results showed that as the ratio of MSC to DC of the coculture system increased and the coculture time of the two cells prolonged, the concentrations of Gal-1, interleukin- (IL-) 10, and IL-12 in the supernatants were increased and the protein expression of Gal-1 on and within DCs was also enhanced. The phosphorylation of extracellular signal-regulated kinase (ERK) pathway in DCs was boosted, whereas p38 mitogen-activated protein kinase (MAPK) pathway phosphorylation was weakened. Meanwhile, the expression of costimulatory molecules on the surface of DCs was decreased, and the proliferative effect of DCs on allogeneic T cells was also decreased. Therefore, this present study indicated that Gal-1 secreted from MSCs upregulated expression of Gal-1 and stimulated formation of tolerance immunophenotype on DCs, where the underlying mechanism was the regulation of the MAPK signaling pathway in DCs, thereby inhibiting the function of DCs.

Stem cell therapies in age-related neurodegenerative diseases and stroke

Aging, a complex process associated with various structural, functional and metabolic changes in the brain, is an important risk factor for neurodegenerative diseases and stroke. These diseases share similar neuropathological changes, such as the formation of misfolded proteins, oxidative stress, loss of neurons and synapses, dysfunction of the neurovascular unit (NVU), reduction of self-repair capacity, and motor and/or cognitive deficiencies. In addition to gray matter dysfunction, the plasticity and repair capacity of white matter also decrease with aging and contribute to neurodegenerative diseases. Aging not only renders patients more susceptible to these disorders, but also attenuates their self-repair capabilities. In addition, low drug responsiveness and intolerable side effects are major challenges in the prevention and treatment of senile diseases. Thus, stem cell therapies-characterized by cellular plasticity and the ability to self-renew-may be a promising strategy for aging-related brain disorders. Here, we review the common pathophysiological changes, treatments, and the promises and limitations of stem cell therapies in age-related neurodegenerative diseases and stroke.

Serum levels of galectin-1, galectin-3, and galectin-9 are associated with large artery atherosclerotic stroke

The aim of this study was to assess the expression patterns of serum galectin-1 (Gal-1), galectin-3 (Gal-3), galectin-9 (Gal-9), and galectin-3 binding protein (Gal-3BP) and their associations with stroke outcome in large artery atherosclerotic (LAA) stroke. The serum levels of Gal-1, Gal-3, Gal-9, and Gal-3BP were measured by ELISA in 130 patients with LAA stroke and 130 age- and sex-matched controls. Serum samples were collected from the patients on day 1, day 6, and in the 4th week after ischaemic stroke (IS). An unfavourable outcome was defined as a modified Rankin Scale score of >2 on day 90 after IS. Our results indicated that the Gal-3 and Gal-9 levels were higher in patients with LAA stroke than in controls. A higher Gal-3 level was independently associated with an unfavourable outcome both on day 1 and day 6 after IS. In addition, Gal-9 and Gal-1 levels were upregulated on day 6 and in the 4th week after IS, respectively. For Gal-3BP, no difference was detected between patients and controls and no predictive value was found in patients. In conclusion, these findings suggest that the serum levels of Gal-1, Gal-3, and Gal-9 may be associated with LAA stroke.

Ex vivo gene therapy for the treatment of neurological disorders

Ex vivo gene therapy involves the genetic modification of cells outside of the body to produce therapeutic factors and their subsequent transplantation back into patients. Various cell types can be genetically engineered. However, with the explosion in stem cell technologies, neural stem/progenitor cells and mesenchymal stem cells are most often used. The synergy between the effect of the new cell and the additional engineered properties can often provide significant benefits to neurodegenerative changes in the brain. In this review, we cover both preclinical animal studies and clinical human trials that have used ex vivo gene therapy to treat neurological disorders with a focus on Parkinson's disease, Huntington's disease, Alzheimer's disease, ALS, and stroke. We highlight some of the major advances in this field including new autologous sources of pluripotent stem cells, safer ways to introduce therapeutic transgenes, and various methods of gene regulation. We also address some of the remaining hurdles including tunable gene regulation, in vivo cell tracking, and rigorous experimental design. Overall, given the current outcomes from researchers and clinical trials, along with exciting new developments in ex vivo gene and cell therapy, we anticipate that successful treatments for neurological diseases will arise in the near future.

Is Immunomodulation a Principal Mechanism Underlying How Cell-Based Therapies Enhance Stroke Recovery?

Inflammation within the brain and in peripheral tissues contributes to brain injury following ischemic stroke. Therapeutic modulation of the inflammatory response has been actively pursued as a novel stroke treatment approach for decades, without success. In recent years, extensive studies support the high potential for cell-based therapies to become a new treatment modality for stroke and other neurological disorders. In this review, we explore different types of cellular therapies and discuss how they modulate central and peripheral inflammatory processes after stroke. Apart from identifying potential targets for cell therapy, we also discuss paracrine and immunomodulatory mechanisms of cell therapy.

Protective Effect of Galectin-1 during Histoplasma capsulatum Infection Is Associated with Prostaglandin E2 and Nitric Oxide Modulation

Histoplasma capsulatum is a dimorphic fungus that develops a yeast-like morphology in host's tissue, responsible for the pulmonary disease histoplasmosis. The recent increase in the incidence of histoplasmosis in immunocompromised patients highlights the need of understanding immunological controls of fungal infections. Here, we describe our discovery of the role of endogenous galectin-1 (Gal-1) in the immune pathophysiology of experimental histoplasmosis. All infected wild-type (WT) mice survived while only 1/3 of Lgals1^−/− mice genetically deficient in Gal-1 survived 30 days after infection. Although infected Lgals1^−/− mice had increased proinflammatory cytokines, nitric oxide (NO), and elevations in neutrophil pulmonary infiltration, they presented higher fungal load in lungs and spleen. Infected lung and infected macrophages from Lgals1^−/− mice exhibited elevated levels of prostaglandin E₂ (PGE₂, a prostanoid regulator of macrophage activation) and prostaglandin E synthase 2 (Ptgs2) mRNA. Gal-1 did not bind to cell surface of yeast phase of H. capsulatum, in vitro, suggesting that Gal-1 contributed to phagocytes response to infection rather than directly killing the yeast. The data provides the first demonstration of endogenous Gal-1 in the protective immune response against H. capsulatum associated with NO and PGE₂ as an important lipid mediator in the pathogenesis of histoplasmosis.

Increases of Galectin-1 and its S-nitrosylated form in the Brain Tissues of Scrapie-Infected Rodent Models and Human Prion Diseases

Galectin-1 (Gal-1) shows neuroprotective activity in brain ischemia, spinal cord injury, and autoimmune neuroinflammation. To evaluate the Gal-1 situation in the brains of prion disease, the brain levels of Gal-1 in several scrapie-infected experimental rodent models were tested by Western blot, including agents 263K-infected hamsters, 139A-, ME7-, and S15-infected mice. Remarkable increases of brain Gal-1 were observed in all tested scrapie-infected rodents at the terminal stage. The brain levels of Gal-1 showed time-dependent increases along with the prolonging of incubation times. Immunohistochemical assays illustrated much stronger stainings in the brain sections of scrapie-infected rodents. Quantitative RT-PCR of Gal-1 gene demonstrated increased transcription in the brains of scrapie-infected mice. Gal-1 was colocalized with GFAP- and NeuN-positive cells, but not with Iba-1-positive cells in immunofluorescent test. Increases of Gal-1 were also detected in the several postmortem cortex regions of human prion diseases. Moreover, the S-nitrosylated forms of Gal-1 in the brains of scrapie-infected rodents were significantly higher than those of normal ones. Our finding here demonstrates markedly increased brain Gal-1 and S-nitrosylated Gal-1 both in scrapie-infected rodents and human prion diseases.

Functions and mechanisms of microglia/macrophages in neuroinflammation and neurogenesis after stroke

Microglia/macrophages are the major immune cells involved in the defence against brain damage. Their morphology and functional changes are correlated with the release of danger signals induced by stroke. These cells are normally responsible for clearing away dead neural cells and restoring neuronal functions. However, when excessively activated by the damage-associated molecular patterns following stroke, they can produce a large number of proinflammatory cytokines that can disrupt neural cells and the blood-brain barrier and influence neurogenesis. These effects indicate the important roles of microglia/macrophages in the pathophysiological processes of stroke. However, the modifiable and adaptable nature of microglia/macrophages may also be beneficial for brain repair and not just result in damage. These distinct roles may be attributed to the different microglia/macrophage phenotypes because the M1 population is mainly destructive, while the M2 population is neuroprotective. Additionally, different gene expression signature changes in microglia/macrophages have been found in diverse inflammatory milieus. These biofunctional features enable dual roles for microglia/macrophages in brain damage and repair. Currently, it is thought that the proper inflammatory milieu may provide a suitable microenvironment for neurogenesis; however, detailed mechanisms underlying the inflammatory responses that initiate or inhibit neurogenesis remain unknown. This review summarizes recent progress concerning the mechanisms involved in brain damage, repair and regeneration related to microglia/macrophage activation and phenotype transition after stroke. We also argue that future translational studies should be targeting multiple key regulating molecules to improve brain repair, which should be accompanied by the concept of a "therapeutic time window" for sequential therapies.

Galectin-1 inhibitors and their potential therapeutic applications: a patent review

INTRODUCTION

Galectins have affinity for β-galactosides. Human galectin-1 is ubiquitously expressed in the body and its expression level can be a marker in disease. Targeted inhibition of galectin-1 gives potential for treatment of inflammatory disorders and anti-cancer therapeutics.

AREAS COVERED

This review discusses progress in galectin-1 inhibitor discovery and development. Patent applications pertaining to galectin-1 inhibitors are categorised as monovalent- and multivalent-carbohydrate-based inhibitors, peptides- and peptidomimetics. Furthermore, the potential of galectin-1 protein as a therapeutic is discussed along with consideration of the unique challenges that galectin-1 presents, including its monomer-dimer equilibrium and oxidized and reduced forms, with regard to delivering an intact protein to a pathologically relevant site.

EXPERT OPINION

Significant evidence implicates galectin-1's involvement in cancer progression, inflammation, and host-pathogen interactions. Conserved sequence similarity of the carbohydrate-binding sites of different galectins makes design of specific antagonists (blocking agents/inhibitors of function) difficult. Key challenges pertaining to the therapeutic use of galectin-1 are its monomer-dimer equilibrium, its redox state, and delivery of intact galectin-1 to the desired site. Developing modified forms of galectin-1 has resulted in increased stability and functional potency. Gene and protein therapy approaches that deliver the protein toward the target are under exploration as is exploitation of different inhibitor scaffolds.