TLR4-Binding DNA Aptamers Show a Protective Effect against Acute Stroke in Animal Models

ApTOLL: A new therapeutic aptamer for cytoprotection and (re)myelination after multiple sclerosis

BACKGROUND AND PURPOSE

ApTOLL is an aptamer selected to antagonize toll-like receptor 4 (TLR4), a relevant actor for innate immunity involved in inflammatory responses in multiple sclerosis (MS) and other diseases. The currently available therapeutic arsenal to treat MS is composed of immunomodulators but, to date, there are no (re)myelinating drugs available in clinics. In our present study, we studied the effect of ApTOLL on different animal models of MS.

EXPERIMENTAL APPROACH

The experimental autoimmune encephalomyelitis (EAE) model was used to evaluate the effect of ApTOLL on reducing the inflammatory component. A more direct effect on oligodendroglia was studied with the cuprizone model and purified primary cultures of murine and human oligodendrocyte precursor cells (OPCs) isolated through magnetic-activated cell sorting (MACS) from samples of brain cortex. Also, we tested these effects in an ex vivo model of organotypic cultures demyelinated with lysolecithin (LPC).

KEY RESULTS

ApTOLL treatment positively impacted the clinical symptomatology of mice in the EAE and cuprizone models, which was associated with better preservation plus restoration of myelin and oligodendrocytes in the demyelinated lesions of animals. Restoration was corroborated on purified cultures of rodent and human OPCs.

CONCLUSION AND IMPLICATIONS

Our findings reveal a new therapeutic approach for the treatment of inflammatory and demyelinating diseases such as MS. The molecular nature of the aptamer exerts not only an anti-inflammatory effect but also neuroprotective and remyelinating effects. The excellent safety profile demonstrated by ApTOLL in animals and humans opens the door to future clinical trials in MS patients.

Now that the door is open: an update on ischemic stroke pharmacotherapeutics for the neurointerventionalist

The last 10 years have seen a major shift in management of large vessel ischemic stroke with changes towards ever-expanding use of reperfusion therapies (intravenous thrombolysis and mechanical thrombectomy). These strategies 'open the door' to acute therapeutics for ischemic tissue, and we should investigate novel therapeutic approaches to enhance survival of recently reperfused brain. Key insights into new approaches have been provided through translational research models and preclinical paradigms, and through detailed research on ischemic mechanisms. Additional recent clinical trials offer exciting salvos into this new strategy of pairing reperfusion with neuroprotective therapy. This pairing strategy can be employed using drugs that have shown neuroprotective efficacy; neurointerventionalists can administer these during or immediately after reperfusion therapy. This represents a crucial moment when we emphasize reperfusion, and have the technological capability along with the clinical trial experience to lead the way in multiprong approaches to stroke treatment.

Aptamer Technologies in Neuroscience, Neuro-Diagnostics and Neuro-Medicine Development

Aptamers developed using in vitro Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technology are single-stranded nucleic acids 10-100 nucleotides in length. Their targets, often with specificity and high affinity, range from ions and small molecules to proteins and other biological molecules as well as larger systems, including cells, tissues, and animals. Aptamers often rival conventional antibodies with improved performance, due to aptamers' unique biophysical and biochemical properties, including small size, synthetic accessibility, facile modification, low production cost, and low immunogenicity. Therefore, there is sustained interest in engineering and adapting aptamers for many applications, including diagnostics and therapeutics. Recently, aptamers have shown promise as early diagnostic biomarkers and in precision medicine for neurodegenerative and neurological diseases. Here, we critically review neuro-targeting aptamers and their potential applications in neuroscience research, neuro-diagnostics, and neuro-medicine. We also discuss challenges that must be overcome, including delivery across the blood-brain barrier, increased affinity, and improved in vivo stability and in vivo pharmacokinetic properties.

Myeloid cells in vascular dementia and Alzheimer's disease: Possible therapeutic targets?

Growing evidence supports the suggestion that the peripheral immune system plays a role in different pathologies associated with cognitive impairment, such as vascular dementia (VD) or Alzheimer's disease (AD). The aim of this review is to summarize, within the peripheral immune system, the implications of different types of myeloid cells in AD and VD, with a special focus on post-stroke cognitive impairment and dementia (PSCID). We will review the contributions of the myeloid lineage, from peripheral cells (neutrophils, platelets, monocytes and monocyte-derived macrophages) to central nervous system (CNS)-associated cells (perivascular macrophages and microglia). Finally, we will evaluate different potential strategies for pharmacological modulation of pathological processes mediated by myeloid cell subsets, with an emphasis on neutrophils, their interaction with platelets and the process of immunothrombosis that triggers neutrophil-dependent capillary stall and hypoperfusion, as possible effector mechanisms that may pave the way to novel therapeutic avenues to stop dementia, the epidemic of our time. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Immune-Neurovascular Interactions in Experimental Perinatal and Childhood Arterial Ischemic Stroke

Emerging clinical and preclinical data have demonstrated that the pathophysiology of arterial ischemic stroke in the adult, neonates, and children share similar mechanisms that regulate brain damage but also have distinct molecular signatures and involved cellular pathways due to the maturational stage of the central nervous system and the immune system at the time of the insult. In this review, we discuss similarities and differences identified thus far in rodent models of 2 different diseases-neonatal (perinatal) and childhood arterial ischemic stroke. In particular, we review acquired knowledge of the role of resident and peripheral immune populations in modulating outcomes in models of perinatal and childhood arterial ischemic stroke and the most recent and relevant findings in relation to the immune-neurovascular crosstalk, and how the influence of inflammatory mediators is dependent on specific brain maturation stages. Finally, we discuss the current state of treatments geared toward age-appropriate therapies that signal via the immune-neurovascular interaction and consider sex differences to achieve successful translation.

Brain FADE syndrome: the final common pathway of chronic inflammation in neurological disease

Importance

While the understanding of inflammation in the pathogenesis of many neurological diseases is now accepted, this special commentary addresses the need to study chronic inflammation in the propagation of cognitive Fog, Asthenia, and Depression Related to Inflammation which we name Brain FADE syndrome. Patients with Brain FADE syndrome fall in the void between neurology and psychiatry because the depression, fatigue, and fog seen in these patients are not idiopathic, but instead due to organic, inflammation involved in neurological disease initiation.

Observations

A review of randomized clinical trials in stroke, multiple sclerosis, Parkinson's disease, COVID, traumatic brain injury, and Alzheimer's disease reveal a paucity of studies with any component of Brain FADE syndrome as a primary endpoint. Furthermore, despite the relatively well-accepted notion that inflammation is a critical driving factor in these disease pathologies, none have connected chronic inflammation to depression, fatigue, or fog despite over half of the patients suffering from them.

Conclusions and relevance

Brain FADE Syndrome is important and prevalent in the neurological diseases we examined. Classical "psychiatric medications" are insufficient to address Brain FADE Syndrome and a novel approach that utilizes sequential targeting of innate and adaptive immune responses should be studied.

Neuroprotection during Thrombectomy for Acute Ischemic Stroke: A Review of Future Therapies

Stroke is a major cause of death and disability worldwide. Endovascular thrombectomy has been impactful in decreasing mortality. However, many clinical results continue to show suboptimal functional outcomes despite high recanalization rates. This gap in recanalization and symptomatic improvement suggests a need for adjunctive therapies in post-thrombectomy care. With greater insight into ischemia-reperfusion injury, recent preclinical testing of neuroprotective agents has shifted towards preventing oxidative stress through upregulation of antioxidants and downstream effectors, with positive results. Advances in multiple neuroprotective therapies, including uric acid, activated protein C, nerinetide, otaplimastat, imatinib, verapamil, butylphthalide, edaravone, nelonemdaz, ApTOLL, regional hypothermia, remote ischemic conditioning, normobaric oxygen, and especially nuclear factor erythroid 2-related factor 2, have promising evidence for improving stroke care. Sedation and blood pressure management in endovascular thrombectomy also play crucial roles in improved stroke outcomes. A hand-in-hand approach with both endovascular therapy and neuroprotection may be the key to targeting disability due to stroke.

Clinical Translation of Aptamers for COVID-19

The COVID-19 etiologic agent, SARS-CoV-2, continues to be one of the leading causes of death on a global scale. Although efficient methods for diagnosis and treatment of COVID-19 have been developed, new methods of battling SARS-CoV-2 variants and long COVID are still urgently needed. A number of aptamers have demonstrated tremendous potential to be developed into diagnostic and therapeutic agents for COVID-19. The translation of the aptamers for clinical uses, however, has been extremely slow. Overcoming the difficulties faced by aptamers would advance this technology toward clinical use for COVID-19 and other serious disorders.

Aptamers: Features, Synthesis and Applications

Aptamers have become a topic of interest among the researchers and scientists since they not only possess all of the benefits of antibodies but also possess special qualities including heat stability, low cost, and limitless uses⋅ Here we give a review about the features, applications, and challenges of aptamers and also how they are beneficial over the antibodies for biomedical applications. Their unique features make aptamers a prominent tool in therapeutics, diagnostics, biosensors and targeted drug delivery. In conclusion, aptamers represent exciting materials for a variety of applications and can be modified to improve their properties and to extend their applications in biomedical field.

Inhibition of TLR4 Signaling by Isorhapontigenin Targeting of the AHR Alleviates Cerebral Ischemia/Reperfusion Injury

Ischemic stroke is a major risk factor in human health, yet there are no drugs to cure cerebral ischemia/reperfusion injury (CIRI). Inflammation plays a fundamental role in the consequences of CIRI. Isorhapontigenin (ISOR) exhibits great anti-inflammatory activity; however, it is unclear whether ISOR can treat ischemic stroke through an anti-inflammation effect. Here, middle cerebral artery occlusion/reperfusion (MCAO/R) was used to investigate the effects of ISOR on CIRI. The in vitro activity was measured in BV-2 cells exposed to oxygen-glucose deprivation/reperfusion. As measured by neurological scores, brain water content, and infarction, neurological dysfunction was improved in the ISOR group. The neuronal death and microglial activation in the ipsilateral cortex were reduced by ISOR. TLR4 signaling was significantly inhibited by ISOR in vivo and in vitro. By reverse molecular docking, cellular thermal shift, and drug affinity-responsive target stability assays, an aryl hydrocarbon receptor (AHR) was found to be a target of ISOR. Furthermore, AHR knockdown blocked the effect of ISOR on TLR4 signaling, suggesting that ISOR may regulate TLR4-mediated inflammation through AHR, thereby protecting neurons from CIRI. This study demonstrated that ISOR is a promising drug candidate for the treatment of ischemic stroke and provided a theoretical basis for the development of the medicinal value of ISOR-derived foods, such as grapes.

Engineered macromolecular Toll-like receptor agents and assemblies

Macromolecular Toll-like receptor (TLR) agents have been utilized as agonists and inhibitors in preclinical and clinical settings. These agents interface with the TLR class of innate immune receptors which recognize macromolecular ligands that are characteristic of pathogenic material. As such, many agents that have been historically investigated are derived from the natural macromolecules which activate or inhibit TLRs. This review covers recent research and clinically available TLR agents that are macromolecular or polymeric. Synthetic materials that have been found to interface with TLRs are also discussed. Assemblies of these materials are investigated in the context of improving stability or efficacy of ligands. Attention is given to strategies which modify or enhance the current agents and to future outlooks on the development of these agents.

Crystal structure of Leptospira LSS_01692 reveals a dimeric structure and induces inflammatory responses through Toll-like receptor 2-dependent NF-κB and MAPK signal transduction pathways

Leptospirosis is a commonly overlooked zoonotic disease that occurs in tropical and subtropical regions. Recent studies have divided the Leptospira spp. into three groups based on virulence, including pathogenic, intermediate, and saprophytic species. Pathogenic species express a protein family with leucine-rich repeat (LRR) domains, which are less expressed or absent in nonpathogenic species, highlighting the importance of this protein family in leptospirosis. However, the role of LRR domain proteins in the pathogenesis of leptospirosis is still unknown and requires further investigation. In this study, the 3D structure of LSS_01692 (rLRR38) was obtained using X-ray crystallography at a resolution of 3.2 Å. The results showed that rLRR38 forms a typical horseshoe structure with 11 α-helices and 11 β-sheets and an antiparallel dimeric structure. The interactions of rLRR38 with extracellular matrix and cell surface receptors were evaluated using ELISA and single-molecule atomic force microscopy. The results showed that rLRR38 interacted with fibronectin, collagen IV, and Toll-like receptor 2 (TLR2). Incubating HK2 cells with rLRR38 induced two downstream inflammation responses (IL-6 and MCP-1) in the TLR2 signal transduction pathway. The TLR2-TLR1 complex showed the most significant upregulation effects under rLRR38 treatment. Inhibitors also significantly inhibited nuclear factor κB and mitogen-activated protein kinases signals transduction under rLRR38 stimulation. In conclusion, rLRR38 was determined to be a novel LRR domain protein in 3D structure and demonstrated as a TLR2-binding protein that induces inflammatory responses. These structural and functional studies provide a deeper understanding of the pathogenesis of leptospirosis.

Safety and Efficacy of ApTOLL in Patients With Ischemic Stroke Undergoing Endovascular Treatment: A Phase 1/2 Randomized Clinical Trial

Importance

ApTOLL is a TLR4 antagonist with proven preclinical neuroprotective effect and a safe profile in healthy volunteers.

Objective

To assess the safety and efficacy of ApTOLL in combination with endovascular treatment (EVT) for patients with ischemic stroke.

Design, Setting, and Participants

This phase 1b/2a, double-blind, randomized, placebo-controlled study was conducted at 15 sites in Spain and France from 2020 to 2022. Participants included patients aged 18 to 90 years who had ischemic stroke due to large vessel occlusion and were seen within 6 hours after stroke onset; other criteria were an Alberta Stroke Program Early CT Score of 6 to 10, estimated infarct core volume on baseline computed tomography perfusion of 5 to 70 mL, and the intention to undergo EVT. During the study period, 4174 patients underwent EVT.

Interventions

In phase 1b, 0.025, 0.05, 0.1, or 0.2 mg/kg of ApTOLL or placebo; in phase 2a, 0.05 or 0.2 mg/kg of ApTOLL or placebo; and in both phases, treatment with EVT and intravenous thrombolysis if indicated.

Main Outcomes and Measures

The primary end point was the safety of ApTOLL based on death, symptomatic intracranial hemorrhage (sICH), malignant stroke, and recurrent stroke. Secondary efficacy end points included final infarct volume (via MRI at 72 hours), NIHSS score at 72 hours, and disability at 90 days (modified Rankin Scale [mRS] score).

Results

In phase Ib, 32 patients were allocated evenly to the 4 dose groups. After phase 1b was completed with no safety concerns, 2 doses were selected for phase 2a; these 119 patients were randomized to receive ApTOLL, 0.05 mg/kg (n = 36); ApTOLL, 0.2 mg/kg (n = 36), or placebo (n = 47) in a 1:1:√2 ratio. The pooled population of 139 patients had a mean (SD) age of 70 (12) years, 81 patients (58%) were male, and 58 (42%) were female. The primary end point occurred in 16 of 55 patients (29%) receiving placebo (10 deaths [18.2%], 4 sICH [7.3%], 4 malignant strokes [7.3%], and 2 recurrent strokes [3.6%]); in 15 of 42 patients (36%) receiving ApTOLL, 0.05 mg/kg (11 deaths [26.2%], 3 sICH [7.2%], 2 malignant strokes [4.8%], and 2 recurrent strokes [4.8%]); and in 6 of 42 patients (14%) receiving ApTOLL, 0.2 mg/kg (2 deaths [4.8%], 2 sICH [4.8%], and 3 recurrent strokes [7.1%]). ApTOLL, 0.2 mg/kg, was associated with lower NIHSS score at 72 hours (mean difference log-transformed vs placebo, -45%; 95% CI, -67% to -10%), smaller final infarct volume (mean difference log-transformed vs placebo, -42%; 95% CI, -66% to 1%), and lower degrees of disability at 90 days (common odds ratio for a better outcome vs placebo, 2.44; 95% CI, 1.76 to 5.00).

Conclusions and Relevance

In acute ischemic stroke, 0.2 mg/kg of ApTOLL administered within 6 hours of onset in combination with EVT was safe and associated with a potential meaningful clinical effect, reducing mortality and disability at 90 days compared with placebo. These preliminary findings await confirmation from larger pivotal trials.

Trial Registration

ClinicalTrials.gov Identifier: NCT04734548.

Neuroprotective Strategies for Ischemic Stroke-Future Perspectives

Ischemic stroke is the main cause of death and the most common cause of acquired physical disability worldwide. Recent demographic changes increase the relevance of stroke and its sequelae. The acute treatment for stroke is restricted to causative recanalization and restoration of cerebral blood flow, including both intravenous thrombolysis and mechanical thrombectomy. Still, only a limited number of patients are eligible for these time-sensitive treatments. Hence, new neuroprotective approaches are urgently needed. Neuroprotection is thus defined as an intervention resulting in the preservation, recovery, and/or regeneration of the nervous system by interfering with the ischemic-triggered stroke cascade. Despite numerous preclinical studies generating promising data for several neuroprotective agents, successful bench-to-bedside translations are still lacking. The present study provides an overview of current approaches in the research field of neuroprotective stroke treatment. Aside from "traditional" neuroprotective drugs focusing on inflammation, cell death, and excitotoxicity, stem-cell-based treatment methods are also considered. Furthermore, an overview of a prospective neuroprotective method using extracellular vesicles that are secreted from various stem cell sources, including neural stem cells and bone marrow stem cells, is also given. The review concludes with a short discussion on the microbiota-gut-brain axis that may serve as a potential target for future neuroprotective therapies.

Advances in the mechanisms and applications of inhibitory oligodeoxynucleotides against immune-mediated inflammatory diseases

Inhibitory oligodeoxynucleotides (ODNs) are short single-stranded DNA, which capable of folding into complex structures, enabling them to bind to a large variety of targets. With appropriate modifications, the inhibitory oligodeoxynucleotides exhibited many features of long half-life time, simple production, low toxicity and immunogenicity. In recent years, inhibitory oligodeoxynucleotides have received considerable attention for their potential therapeutic applications in immune-mediated inflammatory diseases (IMIDs). Inhibitory oligodeoxynucleotides could be divided into three categories according to its mechanisms and targets, including antisense ODNs (AS-ODNs), DNA aptamers and immunosuppressive ODNs (iSup ODNs). As a synthetic tool with immunomodulatory activity, it can target RNAs or proteins in a specific way, resulting in the reduction, increase or recovery of protein expression, and then regulate the state of immune activation. More importantly, inhibitory oligodeoxynucleotides have been used to treat immune-mediated inflammatory diseases, including inflammatory disorders and autoimmune diseases. Several inhibitory oligodeoxynucleotide drugs have been developed and approved on the market already. These drugs vary in their chemical structures, action mechanisms and cellular targets, but all of them could be capable of inhibiting excessive inflammatory responses. This review summarized their chemical modifications, action mechanisms and applications of the three kinds of inhibitory oligodeoxynucleotidesin the precise treatment of immune-mediated inflammatory diseases.

Beneficial effect of TLR4 blockade by a specific aptamer antagonist after acute myocardial infarction

Experimental evidence indicates that the control of the inflammatory response after myocardial infarction is a key strategy to reduce cardiac injury. Cellular damage after blood flow restoration in the heart promotes sterile inflammation through the release of molecules that activate pattern recognition receptors, among which TLR4 is the most prominent. Transient regulation of TLR4 activity has been considered one of the potential therapeutic interventions with greater projection towards the clinic. In this regard, the characterization of an aptamer (4FT) that acts as a selective antagonist for human TLR4 has been investigated in isolated macrophages from different species and in a rat model of cardiac ischemia/reperfusion (I/R). The binding kinetics and biological responses of murine and human macrophages treated with 4FT show great affinity and significant inhibition of TLR4 signaling including the NF-κB pathway and the LPS-dependent increase in the plasma membrane currents (Kv currents). In the rat model of I/R, administration of 4FT following reoxygenation shows amelioration of cardiac injury function and markers, a process that is significantly enhanced when the second dose of 4FT is administered 24 h after reperfusion of the heart. Parameters such as cardiac injury biomarkers, infiltration of circulating inflammatory cells, and the expression of genes associated with the inflammatory onset are significantly reduced. In addition, the expression of anti-inflammatory genes, such as IL-10, and pro-resolution molecules, such as resolvin D1 are enhanced after 4FT administration. These results indicate that targeting TLR4 with 4FT offers new therapeutic opportunities to prevent cardiac dysfunction after infarction.

Exosomal ZEB1 Derived from Neural Stem Cells Reduces Inflammation Injury in OGD/R-Treated Microglia via the GPR30-TLR4-NF-κB Axis

Ischemic stroke (IS) is the most common type of stroke and the second leading cause of death overall. Neural stem cells play protective roles in IS, but the underlying mechanism remains to be determined. Neural stem cells (NSC) were obtained from the fetal brain tissue of C57BL/6J mice. NSC-derived exosomes (NSC-Exos) were identified in the conditioned medium. Internalization of NSC-Exos was analyzed by fluorescence microscopy. In vitro microglia ischemic stroke injury model was induced using oxygen glucose deprivation/re-oxygenation (OGD/R) method. Cell viability and inflammation were analyzed by MTT, qPCR, ELISA and Western blotting assay. Interaction between ZEB1 and the promoter of GPR30 was verified by luciferase assay and chromatin immunoprecipitation. NSC-Exos prevented OGD/R-mediated inhibition of cell survival and the production of inflammatory cytokines in microglia cells. NSC-Exos increased ZEB1 expression in OGD/R-treated microglia. Down-regulation of ZEB1 expression in NSC-Exos abolished NSC-Exos' protective effects on OGD/R-treated microglia. ZEB1 bound to the promoter region of GPR30 and promoted its expression. Inhibiting GPR30 reversed NSC-Exos effects on cell viability and inflammation injury in OGD/R-treated microglia. Our study demonstrated that NSC exerted cytoprotective roles through release of exosomal ZEB1,which transcriptionally upregulated GPR30 expression, resulting in a reduction in TLR4/NF-κB pathway-induced inflammation. These findings shed light on NSC-Exos' cytoprotective mechanism and highlighted its potential application in the treatment of IS.

Protective effect of pinocembrin from Penthorum chinense Pursh on hepatic ischemia reperfusion injury via regulating HMGB1/TLR4 signal pathway

Hepatic ischemia-reperfusion injury (HIRI) is of common occurrence during liver surgery and transplantation. Pinocembrin (PIN) is a kind of flavonoid monomer extracted from the local traditional Chinese medicine Penthorum chinense Pursh (P. chinense). However, the effect of PIN on HIRI has not determined. We investigated the protective effect and potential mechanism of PIN against HIRI. Model mice were subjected to partial liver ischemia for 60 min, experimental mice were pretreated with PIN orally for 7 days, and H₂ O₂ -induced oxidative damage model in AML12 hepatic cells was established in vitro. Histopathologic analysis and serum biochemical levels revealed that PIN had hepatoprotective activities against HIRI. The variation of GSH, SOD, MDA, and ROS levels indicated that PIN treatments attenuated oxidative stress in tissue. PIN pretreatment obviously ameliorated apoptosis, and restrained the expression of HMGB1 and TLR4 in vivo. In vitro, compared with H₂ O₂ group, the contents of ROS, mitochondrial membrane potential, apoptotic cells, and Bcl-2 protein were decreased, while the Bax protein expression was increased. Moreover, HMGB-1 small interfering RNA test and western blotting showed that PIN pretreatment reduced HMGB1 and TLR4 protein levels. In conclusion, PIN pretreatment effectively protected hepatocytes from HIRI and inhibited the HMGB1/TLR4 signaling pathway.

APRIL: A double-blind, placebo-controlled, randomized, Phase Ib/IIa clinical study of ApTOLL for the treatment of acute ischemic stroke

In the reperfusion era, a new paradigm of treating patients with endovascular treatment (EVT) and neuroprotective drugs is emerging as a promising therapeutic option for patients with acute ischemic stroke (AIS). In this context, ApTOLL, a Toll-like receptor 4 (TLR4) antagonist with proven neuroprotective effect in preclinical models of stroke and a very good pharmacokinetic and safety profile in healthy volunteers, is a promising first-in-class aptamer with the potential to address this huge unmet need. This protocol establishes the clinical trial procedures to conduct a Phase Ib/IIa clinical study (APRIL) to assess ApTOLL tolerability, safety, pharmacokinetics, and biological effect in patients with AIS who are eligible for EVT. This will be a multicenter, double-blind, randomized, placebo-controlled, Phase Ib/IIa clinical study to evaluate the administration of ApTOLL together with EVT in patients with AIS. The study population will be composed of men and non-pregnant women with confirmed AIS with a <6h window from symptoms onset to ApTOLL/placebo administration. The trial is currently being conducted and is divided into two parts: Phase Ib and Phase IIa. In Phase Ib, 32 patients will be allocated to four dose ascending levels to select, based on safety criteria, the best two doses to be administered in the following Phase IIa in which 119 patients will be randomized to three arms of treatment (dose A, dose B, and placebo).

Identification of the trial

EudraCT: 2020-002059-38 and ClinicalTrials.gov Identifier: NCT04734548 https://clinicaltrials.gov/ct2/show/NCT04734548?term=ApTOLL&cond=Stroke&draw=2&rank=1.

Amentoflavone Exerts Anti-Neuroinflammatory Effects by Inhibiting TLR4/MyD88/NF-κB and Activating Nrf2/HO-1 Pathway in Lipopolysaccharide-Induced BV2 Microglia

Background

Amentoflavone, a natural biflavone, exerts anti-inflammation, antioxidation, and antiapoptosis effects on many diseases. However, the mechanism of amentoflavone on neuroinflammation-related diseases has not been comprehensively examined clearly.

Methods

BV2 microglial cells were treated with amentoflavone (10 μM), followed by lipopolysaccharide (LPS). Microglial activation and migration ability and the expression of proinflammatory cytokines and other signaling proteins were determined using immunohistochemistry, immunofluorescence, quantitative real-time polymerase chain reaction, Western blotting, enzyme-linked immunosorbent assay, and wound-healing assays.

Results

Amentoflavone restored LPS-induced microglia activation, migration, and inflammation response which depends on regulating toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor kappa B (NF-κB) pathway. In addition, amentoflavone also enhanced nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) levels in LPS-treated BV2 microglial cells.

Conclusions

Amentoflavone ameliorated LPS-induced neuroinflammatory response and oxidative stress in BV2 microglia. These data provide new insight into the mechanism of amentoflavone in the treatment of neuroinflammation-related diseases. Therefore, amentoflavone may be a potential therapeutic option for neurological disorders.

Loureirin C ameliorates ischemia and reperfusion injury in rats by inhibiting the activation of the TLR4/NF-κB pathway and promoting TLR4 degradation

Ischemic stroke is a leading cause of death and disability worldwide. Post-ischemia, microglia respond immediately to the alternations in neuronal activity and mediate inflammation. Toll-like receptor 4 (TLR4) plays a key role in this phenomenon. To explore the effect of loureirin C, an effective compound from Chinese Dragon's blood, on ischemic stroke, Sprague-Dawley rats were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) with/without intragastric administration of loureirin C (7, 14, and 28 mg/kg). Loureirin C alleviated MCAO/R-induced brain impairment evaluated by neurological scores (p < 0.001), brain water content (p < 0.001), and cerebral infarct volume (p = 0.001). The neuroprotective (p < 0.001) and inhibitory effects on microglial activation (p < 0.001) of loureirin C were revealed by immunofluorescence. Rescue studies with TLR4 overexpression in BV-2 microglia showed that the antiinflammatory effect of loureirin C was attributable to the inhibition of TLR4 protein expression. Moreover, co-immunoprecipitation assays showed that the binding of Triad3A, an E3 ubiquitin ligase of TLR4, was increased by loureirin C (p = 0.003). Our study demonstrates that loureirin C could be a promising therapeutic agent for the management of ischemic stroke by inhibiting microglial activation, potentially by Triad3A-mediated promotion of TLR4 ubiquitination and degradation.

First-in-human phase I clinical trial of a TLR4-binding DNA aptamer, ApTOLL: Safety and pharmacokinetics in healthy volunteers

ApTOLL is an aptamer that antagonizes Toll-like receptor 4 and improves functional outcomes in models of ischemic stroke and myocardial infarction. The aim of this study was to characterize the safety and pharmacokinetics of ApTOLL in healthy volunteers. A first-in-human dose-ascending, randomized, placebo-controlled phase I clinical trial to assess safety and pharmacokinetics of ApTOLL (30-min infusion intravenously) was performed in 46 healthy adult male volunteers. The study was divided into two parts: part A included seven single ascending dose levels, and part B had one multiple dose cohort. Safety and pharmacokinetic parameters were evaluated. No serious adverse events or biochemistry alterations were detected at any dose nor at any administration pattern studied. Maximum concentration was detected at the end of the infusion and mean half-life was 9.3 h. Interestingly, exposure increased in the first four levels receiving doses from 0.7 mg to 14 mg (AUC of 2,441.26 h∗ng/mL to 23,371.11 h∗ng/mL) but remained stable thereafter (mean of 23,184.61 h∗ng/mL after 70 mg). Consequently, the multiple dose study did not show any accumulation of ApTOLL. These results show an excellent safety and adequate pharmacokinetic profile that, together with the efficacy demonstrated in nonclinical studies, provide the basis to start clinical trials in patients.

Immune Pathways in Etiology, Acute Phase, and Chronic Sequelae of Ischemic Stroke

Inflammation and immune mechanisms are crucially involved in the pathophysiology of the development, acute damage cascades, and chronic course after ischemic stroke. Atherosclerosis is an inflammatory disease, and, in addition to classical risk factors, maladaptive immune mechanisms lead to an increased risk of stroke. Accordingly, individuals with signs of inflammation or corresponding biomarkers have an increased risk of stroke. Anti-inflammatory drugs, such as IL (interleukin)-1β blockers, methotrexate, or colchicine, represent attractive treatment strategies to prevent vascular events and stroke. Lately, the COVID-19 pandemic shows a clear association between SARS-CoV2 infections and increased risk of cerebrovascular events. Furthermore, mechanisms of both innate and adaptive immune systems influence cerebral damage cascades after ischemic stroke. Neutrophils, monocytes, and microglia, as well as T and B lymphocytes each play complex interdependent roles that synergize to remove dead tissue but also can cause bystander injury to intact brain cells and generate maladaptive chronic inflammation. Chronic systemic inflammation and comorbid infections may unfavorably influence both outcome after stroke and recurrence risk for further stroke. In addition, stroke triggers specific immune depression, which in turn can promote infections. Recent research is now increasingly addressing the question of the extent to which immune mechanisms may influence long-term outcome after stroke and, in particular, cause specific complications such as poststroke dementia or even poststroke depression.

Anti-HIV Aptamers: Challenges and Prospects

Human Immunodeficiency Virus (HIV) infection continues to be a significant health burden in many countries around the world. Current HIV treatment through a combination of different antiretroviral drugs (cART) effectively suppresses viral replication, but drug resistance and crossresistance are significant challenges. This has prompted the search for novel targets and agents, such as nucleic acid aptamers. Nucleic acid aptamers are oligonucleotides that attach to the target sites with high affinity and specificity. This review provides a target-by-target account of research into anti-HIV aptamers and summarises the challenges and prospects of this therapeutic strategy, specifically in the unique context of HIV infection.

Role of TLR4 in Neutrophil Dynamics and Functions: Contribution to Stroke Pathophysiology

Background and Purpose

The immune response subsequent to an ischemic stroke is a crucial factor in its physiopathology and outcome. It is known that TLR4 is implicated in brain damage and inflammation after stroke and that TLR4 absence induces neutrophil reprogramming toward a protective phenotype in brain ischemia, but the mechanisms remain unknown. We therefore asked how the lack of TLR4 modifies neutrophil function and their contribution to the inflammatory process.

Methods

In order to assess the role of the neutrophilic TLR4 after stroke, mice that do not express TLR4 in myeloid cells (TLR4loxP/Lyz-cre) and its respective controls (TLR4loxP/loxP) were used. Focal cerebral ischemia was induced by occlusion of the middle cerebral artery and infarct size was measured by MRI. A combination of flow cytometry and confocal microscopy was used to assess different neutrophil characteristics (circadian fluctuation, cell surface markers, cell complexity) and functions (apoptosis, microglia engulfment, phagocytosis, NETosis, oxidative burst) in both genotypes.

Results

As previously demonstrated, mice with TLR4 lacking-neutrophils had smaller infarct volumes than control mice. Our results show that the absence of TLR4 keeps neutrophils in a steady youth status that is dysregulated, at least in part, after an ischemic insult, preventing neutrophils from their normal circadian fluctuation. TLR4-lacking neutrophils showed a higher phagocytic activity in the basal state, they were preferentially engulfed by the microglia after stroke, and they produced less radical oxygen species (ROS) in the first stage of the inflammatory process.

Conclusions

TLR4 is specifically involved in neutrophil dynamics under physiological conditions as well as in stroke-induced tissue damage. This research contributes to the idea that TLR4, especially when targeted in specific cell types, is a potential target for neuroprotective strategies.

Pathophysiological and pharmacological relevance of TLR4 in peripheral immune cells after stroke

Stroke is a very common disease being the leading cause of death and disability worldwide. The immune response subsequent to an ischemic stroke is a crucial factor in its physiopathology and outcome. This response is not limited to the injury site. In fact, the immune response to the ischemic process mobilizes mainly circulating cells which upon activation will be recruited to the injury site. When a stroke occurs, molecules that are usually retained inside the cell bodies are released into the extracellular space by uncontrolled cell death. These molecules can bind to the Toll-like receptor 4 (TLR4) in circulating immune cells which are then activated, eliciting, although not exclusively, the inflammatory response to the stroke. In this review, we present an up-to-date summary of the role of the different peripheral immune cells in stroke as well as the role of TLR4 in the function of each cell type in ischemia. Also, we summarize the different antagonists developed against TLR4 and their potential as a pharmacological tool for stroke treatment.

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

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

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

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

New Mechanistic Insights, Novel Treatment Paradigms, and Clinical Progress in Cerebrovascular Diseases

The past decade has brought tremendous progress in diagnostic and therapeutic options for cerebrovascular diseases as exemplified by the advent of thrombectomy in ischemic stroke, benefitting a steeply increasing number of stroke patients and potentially paving the way for a renaissance of neuroprotectants. Progress in basic science has been equally impressive. Based on a deeper understanding of pathomechanisms underlying cerebrovascular diseases, new therapeutic targets have been identified and novel treatment strategies such as pre- and post-conditioning methods were developed. Moreover, translationally relevant aspects are increasingly recognized in basic science studies, which is believed to increase their predictive value and the relevance of obtained findings for clinical application.This review reports key results from some of the most remarkable and encouraging achievements in neurovascular research that have been reported at the 10th International Symposium on Neuroprotection and Neurorepair. Basic science topics discussed herein focus on aspects such as neuroinflammation, extracellular vesicles, and the role of sex and age on stroke recovery. Translational reports highlighted endovascular techniques and targeted delivery methods, neurorehabilitation, advanced functional testing approaches for experimental studies, pre-and post-conditioning approaches as well as novel imaging and treatment strategies. Beyond ischemic stroke, particular emphasis was given on activities in the fields of traumatic brain injury and cerebral hemorrhage in which promising preclinical and clinical results have been reported. Although the number of neutral outcomes in clinical trials is still remarkably high when targeting cerebrovascular diseases, we begin to evidence stepwise but continuous progress towards novel treatment options. Advances in preclinical and translational research as reported herein are believed to have formed a solid foundation for this progress.

Modulation of the Innate Immune Response by Targeting Toll-like Receptors: A Perspective on Their Agonists and Antagonists

Toll-like receptors (TLRs) are a class of proteins that recognize pathogen-associated molecular patterns (PAMPs) and damaged-associated molecular patterns (DAMPs), and they are involved in the regulation of innate immune system. These transmembrane receptors, localized at the cellular or endosomal membrane, trigger inflammatory processes through either myeloid differentiation primary response 88 (MyD88) or TIR-domain-containing adapter-inducing interferon-β (TRIF) signaling pathways. In the last decades, extensive research has been performed on TLR modulators and their therapeutic implication under several pathological conditions, spanning from infections to cancer, from metabolic disorders to neurodegeneration and autoimmune diseases. This Perspective will highlight the recent discoveries in this field, emphasizing the role of TLRs in different diseases and the therapeutic effect of their natural and synthetic modulators, and it will discuss insights for the future exploitation of TLR modulators in human health.

Targeting TLR4 with ApTOLL Improves Heart Function in Response to Coronary Ischemia Reperfusion in Pigs Undergoing Acute Myocardial Infarction

Toll-like receptor 4 (TLR4) contributes to the pathogenesis of coronary ischemia/reperfusion (IR). To test whether the new TLR4 antagonist, ApTOLL, may prevent coronary IR damage, we administered 0.078 mg/kg ApTOLL or Placebo in pigs subjected to IR, analyzing the levels of cardiac troponins, matrix metalloproteinases, pro-, and anti-inflammatory cytokines, heart function, and tissue integrity over a period of 7 days after IR. Our results show that ApTOLL reduced cardiac troponin-1 24 h after administration, improving heart function, as detected by a significant recovery of the left ventricle ejection fraction (LVEF) and the shortening fraction (FS) cardiac parameters. The extension of necrotic and fibrotic areas was also reduced, as detected by Evans blue/2,3,5-triphenyltetrazolium chloride (TTC) staining, Hematoxylin/Eosine, and Masson Trichrome staining of heart sections, together with a significant reduction in the expression of the extracellular matrix-degrading, matrix metalloproteinase 9. Finally, the expression of the following cytokines, CCL1, CCL2, MIP1-A-B, CCL5, CD40L, C5/C5A, CXCL1, CXCL10, CXCL11, CXCL12, G-CSF, GM-CSF, ICAM-1, INF-g, IL1-a, ILI-b, IL-1Ra, IL2, IL4, IL5, IL6, IL8, IL10, IL12, IL13, IL16, IL17-A, IL17- E, IL18, IL21, IL27, IL32, MIF, SERPIN-E1, TNF-a, and TREM-1, were also assayed, detecting a pronounced decrease of pro-inflammatory cytokines after 7 days of treatment with ApTOLL. Altogether, our results show that ApTOLL is a promising new tool for the treatment of acute myocardial infarction (AMI).

Therapeutic targets of oxidative/nitrosative stress and neuroinflammation in ischemic stroke: Applications for natural product efficacy with omics and systemic biology

Oxidative/nitrosative stress and neuroinflammation are critical pathological processes in cerebral ischemia-reperfusion injury, and their intimate interactions mediate neuronal damage, blood-brain barrier (BBB) damage and hemorrhagic transformation (HT) during ischemic stroke. We review current progress towards understanding the interactions of oxidative/nitrosative stress and inflammatory responses in ischemic brain injury. The interactions between reactive oxygen species (ROS)/reactive nitrogen species (RNS) and innate immune receptors such as TLR2/4, NOD-like receptor, RAGE, and scavenger receptors are crucial pathological mechanisms that amplify brain damage during cerebral ischemic injury. Furthermore, we review the current progress of omics and systematic biology approaches for studying complex network regulations related to oxidative/nitrosative stress and inflammation in the pathology of ischemic stroke. Targeting oxidative/nitrosative stress and neuroinflammation could be a promising therapeutic strategy for ischemic stroke treatment. We then review recent advances in discovering compounds from medicinal herbs with the bioactivities of simultaneously regulating oxidative/nitrosative stress and pro-inflammatory molecules for minimizing ischemic brain injury. These compounds include sesamin, baicalin, salvianolic acid A, 6-paradol, silymarin, apocynin, 3H-1,2-Dithiole-3-thione, (-)-epicatechin, rutin, Dl-3-N-butylphthalide, and naringin. We finally summarize recent developments of the omics and systematic biology approaches for exploring the molecular mechanisms and active compounds of Traditional Chinese Medicine (TCM) formulae with the properties of antioxidant and anti-inflammation for neuroprotection. The comprehensive omics and systematic biology approaches provide powerful tools for exploring therapeutic principles of TCM formulae and developing precision medicine for stroke treatment.

DNA aptamers targeting Leishmania infantum H3 protein as potential diagnostic tools

Leishmaniasis is a disease caused by a parasite of the genus Leishmania that affects millions of people worldwide. These parasites are characterized by the presence of a DNA-containing granule, the kinetoplastid, located in the single mitochondrion at the base of the cell's flagellum. Interestingly, these flagellates do not condense chromatin during mitosis, possibly due to the specific molecular features of their histones. Although histones are extremely conserved proteins, kinetoplastid core histone sequences diverge significantly from those of higher eukaryotes. This divergence makes kinetoplastid core histones potential diagnostic and/or therapeutic targets. Aptamers are short single-stranded nucleic acids that are able to recognize target molecules with high affinity and specificity. Their binding capacity is a consequence of the particular three-dimensional structure acquired depending on their sequence. These molecules are currently used for detection, diagnosis and therapeutic purpose. Starting from a previously obtained ssDNA aptamer population against rLiH3 protein we have isolated two individual aptamers, AptLiH3#4 and AptLiH3#10. Next, we have performed ELONA, Western blot and slot blot assays to establish aptamer specificity and affinity for LiH3 histone. In addition, ELONA assays using peptides corresponding to overlapped sequences of LiH3 were made to map the aptamers:LiH3 interaction. Finally, different assays using aptamers were performed in order to evaluate the possibility of using these aptamers as sensing molecule to recognize the endogenous protein LiH3. Our results indicate that both aptamers have high affinity and specificity for the target and are able to detect the endogenous LiH3 histone protein in promastigotes lysates. In silico analysis reveals that these two aptamers have different potential secondary structure among them, however, both of them are able to recognize the same peptide sequences present in the protein. In conclusion, our findings indicate that these aptamers could be used for LiH3 histone detection and, in consequence, as potential biosensing molecules in a diagnostic tool for leishmaniasis.

Targeting TLR4-dependent inflammation in post-hemorrhagic brain injury

Recent data have implicated inflammation of the cerebrospinal fluid spaces after subarachnoid, intraventricular, and intracerebral hemorrhage to be a critical driver of multiple secondary brain injuries such as hydrocephalus, cerebral edema, and vasospasm. While TLR4-dependent reparative inflammation is an important protective response that can eliminate physical irritants and damaged cells, sustained or inappropriately triggered inflammation can initiate or propagate disease.Areas covered: We review recent advances in our understanding of how TLR4, including its upstream damage-associated molecular patterns and its downstream MyD88-dependent and independent signaling pathways, contributes to hemorrhage-induced inflammation in numerous brain diseases. We discuss prospects for the pharmacotherapeutic targeting of TLR4 in these disorders, including the use of repurposed FDA-approved agents.Expert opinion: TLR4 inhibitors with good blood-brain-barrier (BBB) penetration could be useful adjuncts in post-hemorrhagic hydrocephalus and multiple other diseases associated with brain hemorrhage and inflammation.

TLR4-Targeting Therapeutics: Structural Basis and Computer-Aided Drug Discovery Approaches

The integration of computational techniques into drug development has led to a substantial increase in the knowledge of structural, chemical, and biological data. These techniques are useful for handling the big data generated by empirical and clinical studies. Over the last few years, computer-aided drug discovery methods such as virtual screening, pharmacophore modeling, quantitative structure-activity relationship analysis, and molecular docking have been employed by pharmaceutical companies and academic researchers for the development of pharmacologically active drugs. Toll-like receptors (TLRs) play a vital role in various inflammatory, autoimmune, and neurodegenerative disorders such as sepsis, rheumatoid arthritis, inflammatory bowel disease, Alzheimer's disease, multiple sclerosis, cancer, and systemic lupus erythematosus. TLRs, particularly TLR4, have been identified as potential drug targets for the treatment of these diseases, and several relevant compounds are under preclinical and clinical evaluation. This review covers the reported computational studies and techniques that have provided insights into TLR4-targeting therapeutics. Furthermore, this article provides an overview of the computational methods that can benefit a broad audience in this field and help with the development of novel drugs for TLR-related disorders.

[Expression of TLR4/MyD88/NF-κB pathway genes and its related inflammatory factors in secondary spinal cord injury]

OBJECTIVE

To investigate the expression of Toll-like receptor 4 (TLR4)/myeloid differentiation factor (MyD88)/nuclear factor-κB (NF-κB) pathway genes and related inflammatory factors tumor necrosis factor-α (TNF-α), interleukin (IL)-12, IL-6 in patients with secondary spinal cord injury (SSCI) and the correlations with prognosis.

METHODS

The clinical data of 105 SSCI patients and 40 healthy subjects were reviewed. According to Frankel's classification of spinal cord injury, the patients were divided into complete injury group and incomplete injury group, and according to the improvement of Japanese Orthopedic Association (JOA) scores, the patients were divided into good prognosis group and poor prognosis group. The expression of TLR4, MyD88, NF-κB in peripheral blood mononuclear cells (PBMC) and serum TNF-α, IL-12, IL-6 levels were compared between SSCI patients and healthy controls, between patients with complete and incomplete injury, between patients with poor and good prognosis. Logistic regression analysis was used to analyze the risk factors leading to poor prognosis of SSCI, and Pearson's correlation analysis was used to analyze the correlation between JOA score and the above indicators.

RESULTS

The expressions of TLR4, MyD88, NF-κB in PBMC and serum TNF-α, IL-12, IL-6 levels in SSCI patients were significantly higher than those in healthy subjects (all P<0.01), those in complete injury group were higher than those in incomplete injury group, and those in poor prognosis group were higher than those in good prognosis group (all P<0.01). The proportions of patients with Frankel grade A, spinal cord edema or hemorrhage, spinal cord injury length longer than 4 cm in poor prognosis group was significantly higher than those in good prognosis group (all P<0.01). Logistic regression analysis showed that Frankel grade, spinal cord edema or hemorrhage, length of spinal cord injury, relative expressions of TLR4, MyD88, NF-κB in PBMC, serum levels of TNF-α, IL-12 and IL-6 were risk factors for poor prognosis in SSCI patients (P<0.05 or P<0.01). Pearson's correlation analysis showed that JOA improvement rate was negatively correlated with the relative expressions of TLR4, MyD88, NF-κB mRNA in PBMC and serum TNF-α, IL-12, IL-6 levels (P<0.05 or P<0.01).

CONCLUSIONS

The activation of TLR4/MyD88/NF-κB pathway and the up-regulation of the expression of related inflammatory factors TNF-α, IL-12 and IL-6 are involved in the progression of SSCI, which are closely related to the neuroinflammatory injury, and can be used as reference indexes for evaluating prognosis in SSCI patients.

Role of TLR4 (Toll-Like Receptor 4) in N1/N2 Neutrophil Programming After Stroke

Background and Purpose- After stroke, the population of infiltrated neutrophils in the brain is heterogeneous, including a population of alternative neutrophils (N2) that express M2 phenotype markers. We explored the role of TLR4 (toll-like receptor 4) on neutrophil infiltration and polarization in this setting. Methods- Focal cerebral ischemia was induced by occlusion of the middle cerebral artery occlusion in TLR4-KO and WT (wild type) mice. Infarct size was measured by Nissl staining and magnetic resonance imaging. Leukocyte infiltration was quantified 48 hours after middle cerebral artery occlusion by immunofluorescence and flow cytometry. To elucidate mechanisms underlying TLR4-mediated N2 phenotype, a cDNA microarray analysis was performed in neutrophils isolated from blood 48 hours after stroke in WT and TLR4-KO mice. Results- As demonstrated previously, TLR4-deficient mice presented lesser infarct volumes than WT mice. TLR4-deficient mice showed higher density of infiltrated neutrophils 48 hours after stroke compared with WT mice, concomitantly to neuroprotection. Furthermore, cytometric and stereological analyses revealed an increased number of N2 neutrophils (YM1⁺ cells) into the ischemic core in TLR4-deficient mice, suggesting a protective effect of this neutrophil subset that was corroborated by depleting peripheral neutrophils or using mice with TLR4 genetically ablated in the myeloid lineage. Finally, cDNA microarray analysis in neutrophils, confirmed by quantitative polymerase chain reaction, showed that TLR4 modulates several pathways associated with ischemia-induced inflammation, migration of neutrophils into the parenchyma, and their functional priming, which might explain the opposite effect on outcome of the different neutrophil subsets. Conclusions- TLR4 deficiency increased the levels of alternative neutrophils (N2)-an effect associated with neuroprotection after stroke-supporting that modulation of neutrophil polarization is a major target of TLR4 and highlighting the crucial role of TLR4 at the peripheral level after stroke. Visual Overview- An online visual overview is available for this article.

Recent Advances in Aptamer Discovery and Applications

Aptamers are short, single-stranded DNA, RNA, or synthetic XNA molecules that can be developed with high affinity and specificity to interact with any desired targets. They have been widely used in facilitating discoveries in basic research, ensuring food safety and monitoring the environment. Furthermore, aptamers play promising roles as clinical diagnostics and therapeutic agents. This review provides update on the recent advances in this rapidly progressing field of research with particular emphasis on generation of aptamers and their applications in biosensing, biotechnology and medicine. The limitations and future directions of aptamers in target specific delivery and real-time detection are also discussed.

Aptamer Chimeras for Therapeutic Delivery: The Challenging Perspectives

Nucleic acid-based aptamers have emerged as efficient delivery carriers of therapeutics. Thanks to their unique features, they can be, to date, considered one of the best targeting moieties, allowing the specific recognition of diseased cells and avoiding unwanted off-target effects on healthy tissues. In this review, we revise the most recent contributes on bispecific and multifunctional aptamer therapeutic chimeras. We will discuss key examples of aptamer-mediated delivery of nucleic acid and peptide-based therapeutics underlying their great potentiality and versatility. Achieved objectives and challenges will be highlighted as well.