Chemokine receptors: signposts to brain development and disease

Astrocyte-Microglia Crosstalk: A Novel Target for the Treatment of Migraine

Migraine is a pervasive neurologic disease closely related to neurogenic inflammation. The astrocytes and microglia in the central nervous system are vital in inducing neurogenic inflammation in migraine. Recently, it has been found that there may be a crosstalk phenomenon between microglia and astrocytes, which plays a crucial part in the pathology and treatment of Alzheimer's disease and other central nervous system diseases closely related to inflammation, thus becoming a novel hotspot in neuroimmune research. However, the role of the crosstalk between microglia and astrocytes in the pathogenesis and treatment of migraine is yet to be discussed. Based on the preliminary literature reports, we have reviewed relevant evidence of the crosstalk between microglia and astrocytes in the pathogenesis of migraine and summarized the crosstalk pathways, thereby hoping to provide novel ideas for future research and treatment.

The origin, evolution, and molecular diversity of the chemokine system

Chemokine signalling performs key functions in cell migration via chemoattraction, such as attracting leukocytes to the site of infection during host defence. The system consists of a ligand, the chemokine, usually secreted outside the cell, and a chemokine receptor on the surface of a target cell that recognises the ligand. Several noncanonical components interact with the system. These include a variety of molecules that usually share some degree of sequence similarity with canonical components and, in some cases, are known to bind to canonical components and/or to modulate cell migration. Whereas canonical components have been described in vertebrate lineages, the distribution of the noncanonical components is less clear. Uncertainty over the relationships between canonical and noncanonical components hampers our understanding of the evolution of the system. We used phylogenetic methods, including gene-tree to species-tree reconciliation, to untangle the relationships between canonical and noncanonical components, identify gene duplication events, and clarify the origin of the system. We found that unrelated ligand groups independently evolved chemokine-like functions. We found noncanonical ligands outside vertebrates, such as TAFA "chemokines" found in urochordates. In contrast, all receptor groups are vertebrate-specific and all-except ACKR1-originated from a common ancestor in early vertebrates. Both ligand and receptor copy numbers expanded through gene duplication events at the base of jawed vertebrates, with subsequent waves of innovation occurring in bony fish and mammals.

Causality between rheumatoid arthritis and the risk of cognitive impairment: a Mendelian randomization study

BACKGROUND

There is mounting proof that rheumatoid arthritis (RA) and cognitive decline are related. These studies, however, have not all been uniform, and others have not discovered such a correlation. It is essential to investigate the link between RA and cognitive decline.

METHOD

We conducted a Mendelian randomization analysis utilizing three different publicly accessible RA GWAS summary datasets and a variety of meticulously verified instrumental variables. We mostly used inverse variance weighting (IVW), as well as MR-Egger, weighted median, MR-PRESSO, and several sensitivity analyses, to figure out the link between RA and cognitive impairment (CI).

RESULTS

Our MR study identified the causality between RA and declining cognitive performance (β = - 0.010, 95% CI of - 0.017 to - 0.003, P = 4.33E-03) and cognitive function (β = - 0.029, 95% CI of - 0.053 to - 0.005, P = 1.93E-02). The consistent direction of the connection is revealed by sensitivity analysis utilizing the weighted median and the MR-Egger method. Furthermore, we reproduced our findings across two additional RA datasets and found identical outcomes, strengthening the validity of our findings.

CONCLUSION

This study offers proof of causality between RA and an increased risk of CI. Our findings highlight the importance of examining RA patients for cognitive ability, which may open up fresh ideas for the prevention of CI.

Neural stem cells transplantation combined with ethyl stearate improve PD rats motor behavior by promoting NSCs migration and differentiation

BACKGROUND

In recent years, the ability of neural stem cells (NSCs) transplantation to treat Parkinson's disease (PD) has attracted attention. However, it is still a challenge to promote the migration of NSCs to the lesion site and their directional differentiation into dopaminergic neurons in PD. C-C motif chemokine ligand 5 (CCL5) and C-C motif chemokine receptor 5 (CCR5) are expressed in the brain and are important regulators of cell migration. It has been reported that ethyl stearate (PubChem CID: 8122) has a protective effect in 6-OHDA-induced PD rats.

METHODS

Parkinson's disease rats were injected with 6-hydroxydopamine (6-OHDA) into the right substantia nigra, and striatum followed by 8 μL of an NSC cell suspension containing 100 μM ethyl stearate and 8 × 10⁵ cells in the right striatum. The effect of transplantation NSCs combined with ethyl stearate was assessed by evaluating apomorphine (APO)-induced turning behavior and performance in the pole test. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR), Western blotting (WB), and immunofluorescence staining were also performed.

RESULTS

NSCs transplantation combined with ethyl stearate ameliorated the behavioral deficits of PD rats. PD rats that received transplantation NSCs combined with ethyl stearate exhibited increased expression of tyrosine hydroxylase (TH) and an increased number of green fluorescent protein (GFP)-positive cells. Furthermore, GFP-positive cells migrated into the substantia nigra and differentiated into dopaminergic neurons. The expression of CCL5 and CCR5 was significantly increased after transplantation NSCs combined with ethyl stearate.

CONCLUSIONS

These findings suggest that NSCs transplantation combined with ethyl stearate can improve the motor behavioral performance of PD rats by promoting NSCs migration from the striatum to the substantia nigra via CCL5/CCR5 and promoting the differentiation of NSCs into dopaminergic neurons.

Physical associations of microglia and the vascular blood-brain barrier and their importance in development, health, and disease

Brain endothelial cells (BEC) of the vascular blood-brain barrier (BBB) interact with many different cell types in the brain, including microglia, the brain's resident immune cells. Physical associations of microglia with the BBB and the importance of these interactions in health and disease are an emerging area of study and likely involved in neuroimmune communication. In this mini-review, we consider how microglia and the BBB are intrinsically linked in the developing brain, discuss possible mechanisms that attract microglia to the vasculature in healthy physiological conditions, and examine the known microglial-vascular associated changes in systemic infection and various disease states. Our findings shed light on the complexities of microglial-vascular interactions and highlight the contributions of microglia to the functions of the neurovascular unit.

Decreased Microglia in Pax2 Mutant Mice Leads to Impaired Learning and Memory

Impaired learning and memory ability is one of the characteristics of a variety of neurological diseases, and its molecular mechanisms are complex and diverse and are regulated by a variety of factors. It is generally believed that synaptic plasticity plays an important role in the process of learning and memory. The protein encoded by the Pax2 gene is a transcription factor involved in neuron migration and cell fate determination during neural development. Mice knocked out of BDNF in the Pax2 lineage-derived interneuron precursor exhibited learning disabilities and severe cognitive impairment. In this study, Pax2 heterozygous gene (Pax2^+/- mice) deletion mice were used as the research objects and behavioral tests were used to observe the effect of Pax2 gene deletion on learning and memory ability; morphological and molecular biological methods were used to observe the effect of Pax2 gene deletion on the neural structure. Single-cell transcriptome sequencing was used to observe the cell subtypes and differentially expressed genes (DEGs) and signaling pathways affected by Pax2 gene deletion and the possible molecular mechanisms. The results showed that Pax2^+/- mice had impaired learning and memory ability, abnormal synaptic structure, and significantly reduced number of microglia clusters, and DEGs were associated with pro-inflammatory chemokines. Finally, we speculate that Pax2 gene deletion may lead to abnormal chemokines and chemokine receptors by affecting microglia.

Neuro-immune interactions at single-cell resolution in neurodevelopmental, infectious, and neurodegenerative diseases

Recent technological advance in single-cell and single-nucleus transcriptomics has made it possible to generate an unprecedentedly detailed landscape of neuro-immune interactions in healthy and diseased brains. In this review, we overview the recent literature that catalogs single-cell-level gene expression in brains with signs of inflammation, focusing on maternal immune activation, viral infection, and auto-immune diseases. The literature also includes a series of papers that provide strong evidence for immunological contributions to neurodegenerative diseases, which, in a strict sense, are not considered neuroinflammatory. To help with the discussion, we present a diagram of experimental and analytical flows in the single-cell analysis of the brain. We also discuss the recurring themes of neuro-immune interactions and suggest future research directions.

Temporal alteration of microglia to microinfarcts in rat brain induced by the vascular occlusion with fluorescent microspheres

Microglia, the resident immune cells in the central nervous system, can monitor the microenvironment and actively respond to ischemic stroke and other brain injuries. In this procedure, microglia and neurons can cross-talk via transmembrane chemokine, Fractalkine (CX3CL1), to impact one another. We used a rat model of multifocal microinfarcts induced by the injection of fluorescent microspheres into the right common carotid artery and examined the morphological alteration of blood vessels, microglia, astrocytes, and neurons at 6 h, 1, 7, and 14 days after modeling, along with neurobehavioral tests and the staining of CX3CL1 in this study. Our results demonstrated that in the infarcted regions, astrocytes and microglia activated in response to neuronal degeneration and upregulation of cleaved caspase-3, which occurred concurrently with vascular alteration and higher expression of CX3CL1. We provided sequential histological data to shed light on the morphological changes after modeling, which would help in the identification of new targets and the choice of the ideal time window for therapeutic intervention in ischemic stroke.

Recent Advances in the Molecular and Cellular Mechanisms of gp120-Mediated Neurotoxicity

Axonal degeneration and loss of synapses are often seen in different brain areas of people living with human immunodeficiency virus (HIV). Nevertheless, the underlying causes of the pathological alterations observed in these individuals are poorly comprehended, considering that HIV does not infect neurons. Experimental data have shown that viral proteins, including the envelope protein gp120, cause synaptic pathology followed by neuronal cell death. These neurotoxic effects on synapses could be the result of a variety of mechanisms that decrease synaptic plasticity. In this paper, we will briefly present new emerging concepts connected with the ability of gp120 to promote the degeneration of synapses by either directly damaging the axonal cytoskeleton and/or the indirect activation of the p75 neurotrophin receptor death domain in dendrites.

Linking Diabetes Mellitus with Alzheimer's Disease: Bioinformatics Analysis for the Potential Pathways and Characteristic Genes

As the surging epidemics with significant disability, Alzheimer's disease (AD) and type II diabetes mellitus (T2DM) with microvascular complications are widely prevalent, sharing considerable similarities in putative pathomechanism. Despite a spurt of researches on the biology, knowledge about their interactive mechanisms is still rudimentary. Applying bioinformatics ways to explore the differentially co-expressed genes contributes to achieve our objectives to find new therapeutic targets. In this study, we firstly integrated gene expression omnibus datasets (GSE28146 and GSE43950) to identify differentially expressed genes. The enrichment analysis of pivotal genes, like gene ontology and pathway signaling proceeded subsequently. Besides, the related protein-protein interaction (PPI) network was then constructed. To further explain the inner connections, we ended up unearthing the biological significance of valuable targets. As a result, a set of 712, 630, 487, and 997 genes were differentially identified in T2DM with microvascular complications and AD at incipient, moderate, and severe, respectively. The enrichment analysis involving both diseases implicated the dominance of immune system, especially the noteworthy chemokine signaling. Multiple comparisons confirmed that CACNA2D3, NUMB, and IER3 were simultaneously participate in these two conditions, whose respective associations with neurological and endocrine diseases, and regulators including interacting chemicals, transcription factors, and miRNAs were analyzed. Bioinformatics analysis eventually concluded that immune-related biological functions and pathways closely link AD and T2DM with microvascular complications. Further exploration of the regulatory factors about CACNA2D3, NUMB, and IER3 in neuroendocrine field may provide us a promising direction to discover potential strategies for the comorbidity status.

Functional immune cell-astrocyte interactions

Astrocytes are abundant glial cells in the central nervous system (CNS) that control multiple aspects of health and disease. Through their interactions with components of the blood–brain barrier (BBB), astrocytes not only regulate BBB function, they also sense molecules produced by peripheral immune cells, including cytokines. Here, we review the interactions between immune cells and astrocytes and their roles in health and neurological diseases, with a special focus on multiple sclerosis (MS). We highlight known pathways that participate in astrocyte crosstalk with microglia, NK cells, T cells, and other cell types; their contribution to the pathogenesis of neurological diseases; and their potential value as therapeutic targets.

Neural Stem Cells for Early Ischemic Stroke

Clinical treatments for ischemic stroke are limited. Neural stem cell (NSC) transplantation can be a promising therapy. Clinically, ischemia and subsequent reperfusion lead to extensive neurovascular injury that involves inflammation, disruption of the blood-brain barrier, and brain cell death. NSCs exhibit multiple potentially therapeutic actions against neurovascular injury. Currently, tissue plasminogen activator (tPA) is the only FDA-approved clot-dissolving agent. While tPA’s thrombolytic role within the vasculature is beneficial, tPA’s non-thrombolytic deleterious effects aggravates neurovascular injury, restricting the treatment time window (time-sensitive) and tPA eligibility. Thus, new strategies are needed to mitigate tPA’s detrimental effects and quickly mediate vascular repair after stroke. Up to date, clinical trials focus on the impact of stem cell therapy on neuro-restoration by delivering cells during the chronic stroke stage. Also, NSCs secrete factors that stimulate endogenous repair mechanisms for early-stage ischemic stroke. This review will present an integrated view of the preclinical perspectives of NSC transplantation as a promising treatment for neurovascular injury, with an emphasis on early-stage ischemic stroke. Further, this will highlight the impact of early sub-acute NSC delivery on improving short-term and long-term stroke outcomes.

Identification of tissue-specific expression of CXCL14 in black rockfish (Sebastes schlegelii)

CXCL14 is a chemokine which is orthologous in mammals and fish. CXCL14 has a functional role in different organs, with immunomodulatory functions in mammals, but its expression and function in fish is not well known. Moreover, it shows no effects related to immunity in the central nervous system or the reproductive tract in diverse species. Black rockfish (Sebastes schlegelii) is an economically important fish in Asian countries, whose CXCL14 expression pattern is yet to be understood. In this study, the homology of the CXCL14 amino acid sequence in S. schlegelii was compared with that in other species, including fish. Moreover, in situ hybridization analysis revealed that it was highly expressed in the brain and ovary of S. schlegelii. Taken together, we identified for the first time, the cell-specific expression of CXCL14 in S. schlegelii.

Dendritic Cells: Neglected Modulators of Peripheral Immune Responses and Neuroinflammation in Mood Disorders?

Affective disorders (AD) including major depressive disorder (MDD) and bipolar disorder (BD) are common mood disorders associated with increased disability and poor health outcomes. Altered immune responses characterized by increased serum levels of pro-inflammatory cytokines and neuroinflammation are common findings in patients with AD and in corresponding animal models. Dendritic cells (DCs) represent a heterogeneous population of myeloid cells that orchestrate innate and adaptive immune responses and self-tolerance. Upon sensing exogenous and endogenous danger signals, mature DCs secrete proinflammatory factors, acquire migratory and antigen presenting capacities and thus contribute to neuroinflammation in trauma, autoimmunity, and neurodegenerative diseases. However, little is known about the involvement of DCs in the pathogenesis of AD. In this review, we summarize the current knowledge on DCs in peripheral immune responses and neuroinflammation in MDD and BD. In addition, we consider the impact of DCs on neuroinflammation and behavior in animal models of AD. Finally, we will discuss therapeutic perspectives targeting DCs and their effector molecules in mood disorders.

Mechanistic insights into the role of the chemokine CCL2/CCR2 axis in dorsal root ganglia to peripheral inflammation and pain hypersensitivity

BACKGROUND

Pain is reported as the leading cause of disability in the common forms of inflammatory arthritis conditions. Acting as a key player in nociceptive processing, neuroinflammation, and neuron-glia communication, the chemokine CCL2/CCR2 axis holds great promise for controlling chronic painful arthritis. Here, we investigated how the CCL2/CCR2 system in the dorsal root ganglion (DRG) contributes to the peripheral inflammatory pain sensitization.

METHODS

Repeated intrathecal (i.t.) administration of the CCR2 antagonist, INCB3344 was tested for its ability to reverse the nociceptive-related behaviors in the tonic formalin and complete Freund's adjuvant (CFA) inflammatory models. We further determined by qPCR the expression of CCL2/CCR2, SP and CGRP in DRG neurons from CFA-treated rats. Using DRG explants, acutely dissociated primary sensory neurons and calcium mobilization assay, we also assessed the release of CCL2 and sensitization of nociceptors. Finally, we examined by immunohistochemistry following nerve ligation the axonal transport of CCL2, SP, and CGRP from the sciatic nerve of CFA-treated rats.

RESULTS

We first found that CFA-induced paw edema provoked an increase in CCL2/CCR2 and SP expression in ipsilateral DRGs, which was decreased after INCB3344 treatment. This upregulation in pronociceptive neuromodulators was accompanied by an enhanced nociceptive neuron excitability on days 3 and 10 post-CFA, as revealed by the CCR2-dependent increase in intracellular calcium mobilization following CCL2 stimulation. In DRG explants, we further demonstrated that the release of CCL2 was increased following peripheral inflammation. Finally, the excitation of nociceptors following peripheral inflammation stimulated the anterograde transport of SP at their peripheral nerve terminals. Importantly, blockade of CCR2 reduced sensory neuron excitability by limiting the calcium mobilization and subsequently decreased peripheral transport of SP towards the periphery. Finally, pharmacological inhibition of CCR2 reversed the pronociceptive action of CCL2 in rats receiving formalin injection and significantly reduced the neurogenic inflammation as well as the stimuli-evoked and movement-evoked nociceptive behaviors in CFA-treated rats.

CONCLUSIONS

Our results provide significant mechanistic insights into the role of CCL2/CCR2 within the DRG in the development of peripheral inflammation, nociceptor sensitization, and pain hypersensitivity. We further unveil the therapeutic potential of targeting CCR2 for the treatment of painful inflammatory disorders.

Cognitive Decline in Rheumatoid Arthritis: Insight into the Molecular Pathogenetic Mechanisms

Cognitive decline refers to a deterioration of intellectual and learning abilities and related memory problems, and is often associated with behavioral alterations, which prevents sufferers from carrying out the most common daily activities, such as maintaining normal productive interpersonal relationships, communicating, and leading an autonomous life. Numerous studies have highlighted the association between cognitive decline and autoimmune disorders, including rheumatoid arthritis (RA). RA is a chronic, inflammatory, autoimmune disease that involves systems and organs other than the bones and joints, with varying severity among patients. Here, we review the studies investigating the link between cognitive decline and RA, focusing on the main molecular pathogenetic mechanisms involved. The emerging body of data suggests that clinical, psychological, and biological factors may contribute to the pathogenesis of cognitive decline in RA, including cardiovascular complications, chronic pain, depression, inflammatory factors, changes in hormone levels, drug side effects, and genetics. Further studies are warranted in order to fully clarify the basis underlying the association between cognitive decline and RA and to find new possible diagnostic strategies and therapeutic targets for RA patients.

Challenges in researching the immune pathways between early life adversity and psychopathology

Exposure to childhood adversity is a critical risk factor for the development of psychopathology. A growing field of research examines how exposure to childhood adversity is translated into biological risk for psychopathology through alterations in immune system functioning, most notably heightened levels of inflammation biomarkers. Though our knowledge about how childhood adversity can instantiate biological risk for psychopathology is growing, there remain many challenges and gaps in the field to understand how inflammation from childhood adversity contributes to psychopathology. This paper reviews research on the inflammatory outcomes arising from childhood adversity and presents four major challenges that future research must address: (a) the measurement of childhood adversity, (b) the measurement of inflammation, (c) the identification of mediators between childhood adversity and inflammation, and (d) the identification of moderators of inflammatory outcomes following childhood adversity. We discuss synergies and inconsistencies in the literature to summarize the current understanding of the association between childhood adversity, a proinflammatory phenotype, and the biological risk for psychopathology. We discuss the clinical implications of the inflammatory links between childhood adversity and psychopathology, including possibilities for intervention. Finally, this review conclude by delineates future directions for research, including issues of how best to detect, prevent, and understand these “hidden wounds” of childhood adversity.

Inteurleukin-8 gene variations and the susceptibility to schizophrenia

The relevance of Interleukin-8 (IL-8) cytokine alteration in the peripheral and central system has been widely shown in psychosis while variation in the IL-8 gene remains largely unexplored and to the best of our knowledge, IL-8 polymorphisms have never been specifically targeted in Schizophrenia (Scz). Thus, we set out to search a potential correlation between rs4073, rs2227306 and rs1126647 polymorphisms in IL-8 gene and the development of Scz in a sample of the Tunisian population in a candidate gene approach. Targeted polymorphisms were analysed in 206 patients and 195 controls using PCR-RFLP method. Among all analysed polymorphisms, only rs1126647 showed a significant risk for Scz. After stratification analysis, we noted a significant association of TT genotype and T allele at rs1126647 with paranoid form, and more specifically with female sex. We find that the rare haplotypes at rs4073-rs2227306-rs1126647 of TTT, ACT and TCT, each containing the risk allele rs1126647T, were associated with increased risk for paranoid Scz while only the TCT combination constituted a risk factor for Scz more generally. Our findings support that IL-8 gene may be involved in susceptibility to Scz but this still preliminary and needs to be strengthened by further independent analyses.

The Function of Astrocyte Mediated Extracellular Vesicles in Central Nervous System Diseases

Astrocyte activation plays an important role during disease-induced inflammatory response in the brain. Exosomes in the brain could be released from bone marrow (BM)-derived stem cells, neuro stem cells (NSC), mesenchymal stem cells (MSC), etc. We summarized that exosomes release and transport signaling to the target cells, and then produce function. Furthermore, we discussed the pathological interactions between astrocytes and other brain cells, which are related to brain diseases such as stroke, Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) disease, multiple sclerosis (MS), psychiatric, traumatic brain injury (TBI), etc. We provide up-to-date, comprehensive and valuable information on the involvement of exosomes in brain diseases, which is beneficial for basic researchers and clinical physicians.

Metabolic Flexibility Assists Reprograming of Central and Peripheral Innate Immunity During Neurodevelopment

Central innate immunity assists time-dependent neurodevelopment by recruiting and interacting with peripheral immune cells. Microglia are the major player of central innate immunity integrating peripheral signals arising from the circumventricular regions lacking the blood-brain barrier (BBB), via neural afferent pathways such as the vagal nerve and also by choroid plexus into the brain ventricles. Defective and/or unrestrained activation of central and peripheral immunity during embryonic development might set an aberrant connectome establishment and brain function, leading to major psychiatric disorders in postnatal stages. Molecular candidates leading to central and peripheral innate immune overactivation identified metabolic substrates and lipid species as major contributors of immunological priming, supporting the role of a metabolic flexibility node during trained immunity. Mechanistically, trained immunity is established by an epigenetic program including DNA methylation and histone acetylation, as the major molecular epigenetic signatures to set immune phenotypes. By definition, immunological training sets reprogramming of innate immune cells, enhancing or repressing immune responses towards a second challenge which potentially might contribute to neurodevelopment disorders. Notably, the innate immune training might be set during pregnancy by maternal immune activation stimuli. In this review, we integrate the most valuable scientific evidence supporting the role of metabolic cues assisting metabolic flexibility, leading to innate immune training during development and its effects on aberrant neurological phenotypes in the offspring. We also add reports supporting the role of methylation and histone acetylation signatures as a major epigenetic mechanism regulating immune training.

Eotaxins and C-C chemokine receptor type 3 in Parkinson's disease

Parkinson's disease (PD) is one of the most common neuroinflammatory disorders and inflammatory processes seem to play an important role in the pathogenesis of PD. Chemokines as inflammatory mediators, which are involved in the recruitment of leukocytes, can play a role in the pathogenesis of PD. The aim of this study was to examine the serum level of eotaxins (CCL11, CCL24, and CCL26) and the expression of C-C chemokine receptor type 3 (CCR3) in patients with PD compared with healthy subjects. In this study, we measured the serum levels of CCL11, CCL24, and CCL26 with ELISA. In addition, gene and protein expression of CCR3 were measured by RT-PCR and flow cytometry techniques in PD patients (n = 30) and age- and sex-matched healthy subjects (n = 30). All patients suffering from PD were assessed clinically through Unified Parkinson's Disease Rating Scale, Motor Examination (UPDRS ME). The results of this study showed that there was no significant alteration in the serum level of these chemokines and also their receptor among patients with PD and healthy subjects. No significant correlation was observed between the eotaxins serum levels and the clinical measures of PD severity. Based on the results, it can be concluded that eotaxins cannot be considered as appropriate targets for the diagnosis or treatment of PD.

Neuroendocrine-Immune Crosstalk Shapes Sex-Specific Brain Development

Sex is an essential biological variable that significantly impacts multiple aspects of neural functioning in both the healthy and diseased brain. Sex differences in brain structure and function are organized early in development during the critical period of sexual differentiation. While decades of research establish gonadal hormones as the primary modulators of this process, new research has revealed a critical, and perhaps underappreciated, role of the neuroimmune system in sex-specific brain development. The immune and endocrine systems are tightly intertwined and share processes and effector molecules that influence the nervous system. Thus, a natural question is whether endocrine-immune crosstalk contributes to sexual differentiation of the brain. In this mini-review, we first provide a conceptual framework by classifying the major categories of neural sex differences and review the concept of sexual differentiation of the brain, a process occurring early in development and largely controlled by steroid hormones. Next, we describe developmental sex differences in the neuroimmune system, which may represent targets or mediators of the sexual differentiation process. We then discuss the overwhelming evidence in support of crosstalk between the neuroendocrine and immune systems and highlight recent examples that shape sex differences in the brain. Finally, we review how early life events can perturb sex-specific neurodevelopment via aberrant immune activation.

Embryonic microglia influence developing hypothalamic glial populations

Background

Although historically microglia were thought to be immature in the fetal brain, evidence of purposeful interactions between these immune cells and nearby neural progenitors is becoming established. Here, we examined the influence of embryonic microglia on gliogenesis within the developing tuberal hypothalamus, a region later important for energy balance, reproduction, and thermoregulation.

Methods

We used immunohistochemistry to quantify the location and numbers of glial cells in the embryonic brain (E13.5–E17.5), as well as a pharmacological approach (i.e., PLX5622) to knock down fetal microglia. We also conducted cytokine and chemokine analyses on embryonic brains in the presence or absence of microglia, and a neurosphere assay to test the effects of the altered cytokines on hypothalamic progenitor behaviors.

Results

We identified a subpopulation of activated microglia that congregated adjacent to the third ventricle alongside embryonic Olig2+ neural progenitor cells (NPCs) that are destined to give rise to oligodendrocyte and astrocyte populations. In the absence of microglia, we observed an increase in Olig2+ glial progenitor cells that remained at the ventricle by E17.5 and a concomitant decrease of these Olig2+ cells in the mantle zone, indicative of a delay in migration of these precursor cells. A further examination of maturing oligodendrocytes in the hypothalamic grey and white matter area in the absence of microglia revealed migrating oligodendrocyte progenitor cells (OPCs) within the grey matter at E17.5, a time point when OPCs begin to slow their migration. Finally, quantification of cytokine and chemokine signaling in ex vivo E15.5 hypothalamic cultures +/− microglia revealed decreases in the protein levels of several cytokines in the absence of microglia. We assayed the influence of two downregulated cytokines (CCL2 and CXCL10) on neurosphere-forming capacity and lineage commitment of hypothalamic NPCs in culture and showed an increase in NPC proliferation as well as neuronal and oligodendrocyte differentiation.

Conclusion

These data demonstrate that microglia influence gliogenesis in the developing tuberal hypothalamus.

The blockade of CC chemokine receptor type 1 influences the level of nociceptive factors and enhances opioid analgesic potency in a rat model of neuropathic pain

A growing body of evidence has indicated that the release of nociceptive factors, such as interleukins and chemokines, by activated immune and glial cells has crucial significance for neuropathic pain generation and maintenance. Moreover, changes in the production of nociceptive immune factors are associated with low opioid efficacy in the treatment of neuropathy. Recently, it has been suggested that CC chemokine receptor type 1 (CCR1) signaling is important for nociception. Our study provides evidence that the development of hypersensitivity in rats following chronic constriction injury (CCI) of the sciatic nerve is associated with significant up-regulation of endogenous CCR1 ligands, namely, CCL2, CCL3, CCL4, CCL6, CCL7 and CCL9 in the spinal cord and CCL2, CCL6, CCL7 and CCL9 in dorsal root ganglia (DRG). We showed that single and repeated intrathecal administration of J113863 (an antagonist of CCR1) attenuated mechanical and thermal hypersensitivity. Moreover, repeated administration of a CCR1 antagonist enhanced the analgesic properties of morphine and buprenorphine after CCI. Simultaneously, repeated administration of J113863 reduced the protein levels of IBA-1 in the spinal cord and MPO and CD4 in the DRG and, as a consequence, the level of pronociceptive factors, such as interleukin-1β (IL-1β), IL-6 and IL-18. The data obtained provide evidence that CCR1 blockade reduces hypersensitivity and increases opioid-induced analgesia through the modulation of neuroimmune interactions.

Effects of neural stem cell transplantation in Alzheimer's disease models

Currently there are no therapies for treating Alzheimer's disease (AD) that can effectively halt disease progression. Existing drugs such as acetylcholinesterase inhibitors or NMDA receptor antagonists offers only symptomatic benefit. More recently, transplantation of neural stem cells (NSCs) to treat neurodegenerative diseases, including AD, has been investigated as a new therapeutic approach. Transplanted cells have the potential to replace damaged neural circuitry and secrete neurotrophic factors to counter symptomatic deterioration or to alter lesion protein levels. However, since there are animal models that can recapitulate AD in its entirety, it is challenging to precisely characterize the positive effects of transplanting NSCs. In the present review, we discuss the types of mouse modeling system that are available and the effect in each model after human-derived NSC (hNSC) or murine-derived NSC (mNSC) transplantation. Taken together, results from studies involving NSC transplantation in AD models indicate that this strategy could serve as a new therapeutic approach.

Neural stem cell therapy for neurovascular injury in Alzheimer's disease

Alzheimer's disease (AD), the most common form of dementia, is characterized by progressive neurodegeneration leading to severe cognitive decline and eventual death. AD pathophysiology is complex, but neurotoxic accumulation of amyloid-β (Aβ) and hyperphosphorylation of Tau are believed to be main drivers of neurodegeneration in AD. The formation and deposition of Aβ plaques occurs in the brain parenchyma as well as in the cerebral vasculature. Thus, proper blood-brain barrier (BBB) and cerebrovascular functioning are crucial for clearance of Aβ from the brain, and neurovascular dysfunction may be a critical component of AD development. Further, neuroinflammation and dysfunction of angiogenesis, neurogenesis, and neurorestorative capabilities play a role in AD pathophysiology. Currently, there is no effective treatment to prevent or restore loss of brain tissue and cognitive decline in patients with AD. Based on multifactorial and complex pathophysiological cascades in multiple Alzheimer's disease stages, effective AD therapies need to focus on targeting early AD pathology and preserving cerebrovascular function. Neural stem cells (NSCs) participate extensively in mammalian brain homeostasis and repair and exhibit pleiotropic intrinsic properties that likely make them attractive candidates for the treatment of AD. In the review, we summarize the current advances in knowledge regarding neurovascular aspects of AD-related neurodegeneration and discuss multiple actions of NSCs from preclinical studies of AD to evaluate their potential for future clinical treatment of AD.

CCR5: Established paradigms and new frontiers for a 'celebrity' chemokine receptor

Because of the level of attention it received due to its role as the principal HIV coreceptor, CCR5 has been described as a 'celebrity' chemokine receptor. Here we describe the development of CCR5 inhibitory strategies that have been developed for HIV therapy and which are now additionally being considered for use in HIV prevention and cure. The wealth of CCR5-related tools that have been developed during the intensive investigation of CCR5 as an HIV drug target can now be turned towards the study of CCR5 as a model chemokine receptor. We also summarize what is currently known about the cell biology and pharmacology of CCR5, providing an update on new areas of investigation that have emerged in recent research. Finally, we discuss the potential of CCR5 as a drug target for diseases other than HIV, discussing the evidence linking CCR5 and its natural chemokine ligands with inflammatory diseases, particularly neuroinflammation, and certain cancers. These pathologies may provide new uses for the strategies for CCR5 blockade originally developed to combat HIV/AIDS.

Increased CCL6 expression in astrocytes and neuronal protection from neuron-astrocyte interactions

Astrocytes have been reported to exhibit neuroprotective action via various chemokines. Reports of the chemokine CCL6 in central nervous system cells show expression in cultured microglia, but many unexplained effects on neurons and astrocytes remain. In this study, cultured cerebral cortical neurons, astrocytes, and a mixed culture system were constructed, and expression levels of CCL6 and its effects on glutamate neurotoxicity were examined. When neuron cultures and neuron-astrocyte mixed cultures were treated with glutamate, neuronal cell death was observed in both, but was induced by lower concentrations of glutamate in monocultured neurons. In addition, pretreatment of neuron cultures with conditioned media from neuron-astrocyte mixed cultures inhibited glutamate neurotoxicity. CCL6 expression was not observed in fluorescence activated cell sorting analyses of neuron and astrocyte cultures, but was observed in astrocytes from cocultures of neurons and astrocytes. Higher CCL6 concentrations were found in media from cocultures of neurons and astrocytes than in culture media from neuron cultures. Pretreatment of neuron cell cultures with CCL6 for 24 h also protected against glutamate neurotoxicity. This protective effect was suppressed by an antagonist of the chemokine receptor CCR1. Furthermore, glutamate neurotoxicity in mixed neuron and astrocyte cultures was enhanced by pretreatments with the CCR1 antagonist. Finally, cotreatments with the phosphatidylinositol-3 kinase (PI3K) inhibitor and CCL6 abolished the neuroprotective effects of CCL6. These data suggest that astrocytes protect neurons by activating CCR1 in neurons. Moreover, this neuroprotective action of astrocyte CCL6 is mediated by CCR1, and downstream by PI3K.

A role for CXC chemokines and their receptors in stress axis regulation of common carp

Although chemokines mainly function to activate leukocytes and to direct their migration, novel evidence indicates non-immune functions for chemokines within the nervous and endocrine systems. These include development of the nervous system, neuromodulation, neuroendocrine regulation and direct neurotransmitter-like actions. In order to clarify a potential role for chemokines and their receptors in the stress response of fish, we studied changes in the expression patterns of CXC ligands and their receptors in the stress axis organs of carp, during a restraint stress procedure. We showed that stress down-regulated the gene expression of CXCL9-11 (CXCb1 and CXCb2) in stress axis organs and up-regulated expression of CXCR4 chemokine receptor in NPO and pituitary. Moreover, upon stress, reduced gene expression of CXCL12a and CXCL14 was observed in the head kidney. Our results imply that in teleost fish, CXC chemokines and their receptors are involved in neuroendocrine regulation. The active regulation of their expression in stress axis organs during periods of restraint indicates a significant role in the stress response.

CXCL1 and CXCL2 Inhibit the Axon Outgrowth in a Time- and Cell-Type-Dependent Manner in Adult Rat Dorsal Root Ganglia Neurons

The ability to regrow their axons after an injury is a hallmark of neurons in peripheral nervous system which distinguish them from central nervous system neurons. This ability is influenced by their intrinsic capacity to regrow and by the extracellular environment which needs to be supportive of regrowth. CXCL1 [Chemokine (C-X-C motif) Ligand 1] and CXCL2 [Chemokine (C-X-C motif) Ligand 2] are two low-molecular-weight chemokines which can influence neuronal proliferation, differentiation and neurogenesis, but which are also upregulated by injury or inflammation. In this study we investigated the effects of long-term incubation (24, 48 and 72 h) with different concentrations of CXCL1 (0.4, 4 or 40 nM) or CXCL2 (0.36, 3.6 or 36 nM) on the axon outgrowth of adult rat dorsal root ganglia neurons in culture. The results showed that both chemokines significantly inhibited the axon outgrowth, with large and medium NF200 (NeuroFilament 200) (+) dorsal root ganglia neurons affected quicker, compared to small IB4 (Isolectin B4) (+) dorsal root ganglia neurons which were affected after longer exposure. Blocking CXCR2 (C-X-C motif chemokine receptor 2) which mediates the effects of CXCL1 and CXCL2 prevented these effects, suggesting that CXCR2 may represent a new therapeutic target for promoting the axon outgrowth after a peripheral nerve injury.

Chemokines: Key Molecules that Orchestrate Communication among Neurons, Microglia and Astrocytes to Preserve Brain Function

In the CNS, chemokines and chemokine receptors are involved in pleiotropic physiological and pathological activities. Several evidences demonstrated that chemokine signaling in the CNS plays key homeostatic roles and, being expressed on neurons, glia and endothelial cells, chemokines mediate the bidirectional cross-talk among parenchymal cells. An efficient communication between neurons and glia is crucial to establish and maintain a healthy brain environment which ensures normal functionality. Glial cells behave as active sensors of environmental changes induced by neuronal activity or detrimental insults, supporting and exerting neuroprotective activities. In this review we summarize the evidence that chemokines (CXCL12, CX3CL1, CXCL16 and CCL2) modulate neuroprotective processes upon different noxious stimuli and participate to orchestrate neurons-microglia-astrocytes action to preserve and limit brain damage. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.

Immunohistochemical and Molecular Investigations Show Alteration in the Inflammatory Profile of Multiple System Atrophy Brain

Multiple system atrophy (MSA) is an adult-onset neurodegenerative disease characterized by aggregation of α-synuclein in oligodendrocytes to form glial cytoplasmic inclusions. According to the distribution of neurodegeneration, MSA is subtyped as striatonigral degeneration (SND), olivopontocerebellar atrophy (OPCA), or as combination of these 2 (mixed MSA). In the current study, we aimed to investigate regional microglial populations and gene expression in the 3 different MSA subtypes. Microscopy with microglial marker Iba-1 combined with either proinflammatory marker CD68 or anti-inflammatory marker Arginase-1 was analyzed in control, SND, and OPCA cases (n = 5) using paraffin embedded sections. Western immunoblotting and cytokine array were used to determine protein expression in MSA and control brain regions. Gene expression was investigated using the NanoString nCounter Human Inflammation panel v2 mRNA Expression Assay. Analysis of neuropathological subtypes of MSA demonstrated a significant increase in microglia in the substantia nigra of OPCA cases. There was no difference in the microglial activation state in any region. Cytokine expression in MSA was comparable with controls. Decreased expression of CX3CL1 precursor protein and significantly greater CX3CR1 protein was found in MSA. NanoString analysis revealed the >2-fold greater expression of ARG1, MASP1, NOX4, PTGDR2, and C6 in MSA.

Role of chemokines in Parkinson's disease

Parkinson's disease (PD) is a chronic progressive neurodegenerative disorder with an increasing incidence year by year, particularly as the population ages. The most common neuropathologic manifestation in patients with Parkinson's disease is dopamine neurons degeneration and loss in substantia nigra of middle brain. The main neurochemistry problem is the lack of the neurotransmitter dopamine. Clinically, PD patients may also have higher levels of glutamate, gamma-aminobutyric acid, acetylcholine and other neurotransmitters. At present, many data have shown that some chemokines are involved in regulating the release and transmission of neurotransmitters, and the growth and development of related neurons. In recent years, most of the studies relative to PD is based on immune and inflammatory mechanisms, and chemokines is also the focus on this mechanism. Chemokines are a class of cytokines that have definite chemotaxis effects on the different target cells. They might be involved in the pathogenesis of PD by inducing neuronal apoptosis and microglia activation. Clinical data has shown that the levels of chemokines in plasma and cerebrospinal fluid of PD patients have corresponding changes compared with the healthy persons. This review summarizes recent studies on chemokines and their receptors in Parkinson's disease: (i) to explore the role of chemokines in Parkinson's disease; (ii) to provide new indicators for clinical diagnosis of PD; (iii) to provide new targets for drug research and development in the treatment of Parkinson's disease.

Rheumatoid arthritis and depression: an inflammatory perspective

The coexistence of immune-mediated inflammatory diseases with depression has long been recognised. Data that illustrate the intimate associations between peripheral and brain immune responses raise the possibility of shared pathophysiological mechanisms. These associations include the negative effects of proinflammatory cytokines on monoaminergic neurotransmission, neurotrophic factors, and measures of synaptic plasticity. The evidence supporting this association is accumulating and includes findings from clinical trials of immunomodulatory therapy, indicating that these interventions can provide benefits to mental health independent of improvements in physical disease scores. In this Review, we assess this evidence in relation to rheumatoid arthritis and depression, with a focus on innate immune and molecular responses to inflammation, and discuss the challenges of assessing causation in this population, acknowledging the difficulty of assessing the confounding and contributory effects of pain and fatigue. We also discuss how future clinical and preclinical research might improve diagnosis of depression in people with rheumatoid arthritis and shed light on mechanisms that could be substrates for therapeutic interventions.

Nerve cells developmental processes and the dynamic role of cytokine signaling

The stunning diversity of neurons and glial cells makes possible the higher functions of the central nervous system (CNS), allowing the organism to sense, interpret and respond appropriately to the external environment. This cellular diversity derives from a single primary progenitor cell type initiating lineage leading to the formation of both differentiated neurons and glial cells. The processes governing the differentiation of the progenitor pool of cells into mature nerve cells will be here briefly reviewed. They involve morphological transformations, specialized modes of cell division, migration, and controlled cell death, and are regulated through cell-cell interactions and cues provided by the extracellular matrix, as well as by humoral factors from the cerebrospinal fluid and the blood system. In this respect, a quite large body of studies have been focused on cytokines, proteins representing the main signaling network that coordinates immune defense and the maintenance of homeostasis. At the same time, they are deeply involved in CNS development as regulatory factors. This dual role in the nervous system appears of particular relevance for CNS pathology, since cytokine dysregulation (occurring as a consequence of maternal infection, exposure to environmental factors or prenatal hypoxia) can profoundly impact on neurodevelopment and likely influence the response of the adult tissue during neuroinflammatory events.

Prenatal Immune and Endocrine Modulators of Offspring's Brain Development and Cognitive Functions Later in Life

Milestones of brain development in mammals are completed before birth, which provide the prerequisite for cognitive and intellectual performances of the offspring. Prenatal challenges, such as maternal stress experience or infections, have been linked to impaired cognitive development, poor intellectual performances as well as neurodevelopmental and psychiatric disorders in the offspring later in life. Fetal microglial cells may be the target of such challenges and could be functionally modified by maternal markers. Maternal markers can cross the placenta and reach the fetus, a phenomenon commonly referred to as “vertical transfer.” These maternal markers include hormones, such as glucocorticoids, and also maternal immune cells and cytokines, all of which can be altered in response to prenatal challenges. Whilst it is difficult to discriminate between the maternal or fetal origin of glucocorticoids and cytokines in the offspring, immune cells of maternal origin—although low in frequency—can be clearly set apart from offspring's cells in the fetal and adult brain. To date, insights into the functional role of these cells are limited, but it is emergingly recognized that these maternal microchimeric cells may affect fetal brain development, as well as post-natal cognitive performances and behavior. Moreover, the inheritance of vertically transferred cells across generations has been proposed, yielding to the presence of a microchiome in individuals. Hence, it will be one of the scientific challenges in the field of neuroimmunology to identify the functional role of maternal microchimeric cells as well as the brain microchiome. Maternal microchimeric cells, along with hormones and cytokines, may induce epigenetic changes in the fetal brain. Recent data underpin that brain development in response to prenatal stress challenges can be altered across several generations, independent of a genetic predisposition, supporting an epigenetic inheritance. We here discuss how fetal brain development and offspring's cognitive functions later in life is modulated in the turnstile of prenatal challenges by introducing novel and recently emerging pathway, involving maternal hormones and immune markers.

Coadministration of Chemokine Receptor Antagonists with Morphine Potentiates Morphine's Analgesic Effect on Incisional Pain in Rats

Crossdesensitization between opioid and chemokine receptors and involvement of chemokines in pain modulation are well established. We investigated if coadministration of chemokine receptor antagonists (CRAs) with morphine would enhance the analgesic potency of morphine on incisional pain in rats. Animals underwent incisional surgery on the left hind paw and pain responses were evaluated using von Frey filaments at various time points postsurgery between 15 and 360 minutes and daily between 24 and 72 hours. Dose-response curves for morphine, maraviroc (a CCR5 antagonist), and AMD3100 (a CXCR4 antagonist) alone were established. While morphine significantly reduced pain in a time- and dose-dependent manner, maraviroc and AMD3100 had no effect by themselves. Coadministration of either maraviroc or AMD3100 with morphine significantly increased morphine's analgesic effect on incisional pain, shifting the dose-response curve to the left 2.3- and 1.8-fold, respectively. Coadministration of both CRAs with morphine significantly shifted further the morphine dose-response curve to the left 3.3-fold. The effect of treatments on mRNA levels in the draining popliteal lymph node for a panel of chemokines and cytokines showed that message for many of these mediators was upregulated by the incision, and the combination of morphine with the CRAs markedly downregulated them. The data show that combining morphine with CRAs potentiates morphine's analgesic effect on incisional pain. Thus, the same analgesic effect of morphine alone can be achieved with lower doses of morphine when combined with CRAs. Using morphine in lower doses could reduce unwanted side effects and possibly block development of tolerance and dependence.

Potential use of CXCL12/CXCR4 and sonic hedgehog pathways as therapeutic targets in medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor occurring in children, and although high long-term survival rates have been reached with current therapeutic protocols, several neurological injuries are still observed among survivors. It has been shown that the development of MB is highly dependent on the microenvironment surrounding it and that the CXCL12 chemokine and its receptor, CXCR4 and the Sonic Hedgehog (SHH) pathway are crucial for cerebellar development, coordinating proliferation and migration of embryonic cells and malfunctions in these axes can lead to MB development. Indeed, the concomitant overactivation of these axes was suggested to define a new MB molecular subgroup. New molecules are being studied, aiming to inhibit either CXCR4 or the SHH pathways and have been tested in preclinical settings for the treatment of cancers. The use of these molecules could improve MB treatment and save patients from aggressive surgery, chemotherapy and radiotherapy regimens, which are responsible for severe neurological consequences. This review aims to summarize current data about the experimental inhibition of CXCR4 and SHH pathways in MB and its potential implications in treatment of this cancer.

Discovery of a Locally and Orally Active CXCL12 Neutraligand (LIT-927) with Anti-inflammatory Effect in a Murine Model of Allergic Airway Hypereosinophilia

We previously reported Chalcone-4 (1) that binds the chemokine CXCL12, not its cognate receptors CXCR4 or CXCR7, and neutralizes its biological activity. However, this neutraligand suffers from limitations such as poor chemical stability, solubility, and oral activity. Herein, we report on the discovery of pyrimidinone 57 (LIT-927), a novel neutraligand of CXCL12 which displays a higher solubility than 1 and is no longer a Michael acceptor. While both 1 and 57 reduce eosinophil recruitment in a murine model of allergic airway hypereosinophilia, 57 is the only one to display inhibitory activity following oral administration. Thereby, we here describe 57 as the first orally active CXCL12 neutraligand with anti-inflammatory properties. Combined with a high binding selectivity for CXCL12 over other chemokines, 57 represents a powerful pharmacological tool to investigate CXCL12 physiology in vivo and to explore the activity of chemokine neutralization in inflammatory and related diseases.

Neural stem cell therapy for subacute and chronic ischemic stroke

Neural stem cells (NSCs) play vital roles in brain homeostasis and exhibit a broad repertoire of potentially therapeutic actions following neurovascular injury. One such injury is stroke, a worldwide leading cause of death and disability. Clinically, extensive injury from ischemic stroke results from ischemia-reperfusion (IR), which is accompanied by inflammation, blood-brain barrier (BBB) damage, neural cell death, and extensive tissue loss. Tissue plasminogen activator (tPA) is still the only US Food and Drug Administration-approved clot-lysing agent. Whereas the thrombolytic role of tPA within the vasculature is beneficial, the effects of tPA (in a non-thrombolytic role) within the brain parenchyma have been reported as harmful. Thus, new therapies are needed to reduce the deleterious side effects of tPA and quickly facilitate vascular repair following stroke. The Stroke Treatment Academic Industry Roundtable (STAIR) recommends that stroke therapies "focus on drugs/devices/treatments with multiple mechanisms of action and that target multiple pathways". Thus, based on multifactorial ischemic cascades in various stroke stages, effective stroke therapies need to focus on targeting and ameliorating early IR injury as well as facilitating angiogenesis, neurogenesis, and neurorestorative mechanisms following stroke. This review will discuss the preclinical perspectives of NSC transplantation as a promising treatment for neurovascular injury and will emphasize both the subacute and chronic phase of ischemic stroke.

Central fractalkine stimulates central prostaglandin E2 production and induces systemic inflammatory responses

Fractalkine (FKN; CX3CL1) belongs to gamma-chemokine family and binds to CX3CR1 receptors. Currently, the mechanisms involving FKN-induced inflammatory mediators are research targets in an attempt to study immune diseases mechanisms. Besides, FKN seems to modulate inflammation in the nervous system by inducing the secretion of pro-inflammatory mediators such as prostaglandin E₂ (PGE₂). PGE₂ is a classic and important mediator of fever that activates warm-responsive neurons in the anteroventral preoptic region of the hypothalamus (AVPO). Here, we tested the hypothesis that central FKN modulates febrigenic signaling both centrally and peripherally. We performed intracerebroventricular (icv) microinjections of saline (1 μL) or FKN (doses of 5, 50, 500 pg/μL) in rats and measured body temperature (Tb) besides assessing tail skin temperature (Tsk) as a thermoeffector indicator used to calculate the heat loss index (HLI). We also measured the time course changes in AVPO PGE₂, besides plasma corticosterone (CORT) and interleukin-6 (IL-6) levels. FKN induced a long lasting febrile response in which the highest dose (500 pg/μL) induced a marked rise on Tb that was accompanied by a reduced Tsk and HLI, consequently. FKN increased AVPO PGE₂ production in a time-dependent manner besides increasing plasma CORT and IL-6 levels. Our data consistently indicate that FKN increases AVPO PGE₂ production and Tb, accompanied by raised plasma IL-6 levels and activation of the hypothalamus-pituitary-adrenal axis.

Small molecule CXCR4 antagonists block the HIV-1 Nef/CXCR4 axis and selectively initiate the apoptotic program in breast cancer cells

The chemokine receptor CXCR4 plays an integral role in the development of highly metastatic breast cancer and in the pathogenesis of chronic HIV infection. In this study, we compared the effects of CXCR4 antagonists on apoptosis induction in hematopoietic cells and in tumor cells. We incubated cells expressing CXCR4 with a series of CXCR4 antagonists and subsequently exposed the cultures to a pro-apoptotic peptide derived from the HIV-1 Nef protein (NefM1). The NefM1 peptide contains residues 50-60 of Nef and was previously shown to be the sequence necessary for Nef to initiate the apoptotic program through CXCR4 signaling. We found that several of the compounds studied potently blocked Nef-induced apoptosis in Jurkat T-lymphocyte cells. Interestingly, many of the same compounds selectively triggered apoptosis in MDA-MB-231 breast cancer cells, in some cases at sub-nanomolar concentrations. None of the compounds were toxic to lymphocyte, monocyte or macrophage cells, suggesting that aggressive breast cancer carcinomas may be selectively targeted and eliminated using CXCR4-based therapies without additional cytotoxic agents. Our results also demonstrate that not all CXCR4 antagonists are alike and that the observed anti-Nef and pro-apoptotic effects are chemically tunable. Collectively, these findings suggest our CXCR4 antagonists have promising clinical utility for HIV or breast cancer therapies as well as being useful probes to examine the link between CXCR4 and apoptosis.

Why West? Comparisons of clinical, genetic and molecular features of infants with and without spasms

Infantile spasms are the defining seizures of West syndrome, a severe form of early life epilepsy with poorly-understood pathophysiology. We present a novel comparative analysis of infants with spasms versus other seizure-types and identify clinical, etiological, and molecular-genetic factors preferentially predisposing to spasms. We compared ages, clinical etiologies, and associated-genes between spasms and non-spasms groups in a multicenter cohort of 509 infants (<12months) with newly-diagnosed epilepsy. Gene ontology and pathway enrichment analysis of clinical laboratory-confirmed pathogenic variant-harboring genes was performed. Pathways, functions, and cellular compartments between spasms and non-spasms groups were compared. Spasms onset age was similar in infants initially presenting with spasms (6.1 months) versus developing spasms as a later seizure type (6.9 months) but lower in the non-spasms group (4.7 months, p<0.0001). This pattern held across most etiological categories. Gestational age negatively correlated with spasms onset-age (r = -0.29, p<0.0001) but not with non-spasm seizure age. Spasms were significantly preferentially associated with broad developmental and regulatory pathways, whereas motor functions and pathways including cellular response to stimuli, cell motility and ion transport were preferentially enriched in non-spasms. Neuronal cell-body organelles preferentially associated with spasms, while, axonal, dendritic, and synaptic regions preferentially associated with other seizures. Spasms are a clinically and biologically distinct infantile seizure type. Comparative clinical-epidemiological analyses identify the middle of the first year as the time of peak expression regardless of etiology. The inverse association with gestational age suggests the preterm brain must reach a certain post-conceptional, not just chronological, neurodevelopmental stage before spasms manifest. Clear differences exist between the biological pathways leading to spasms versus other seizure types and suggest that spasms result from dysregulation of multiple developmental pathways and involve different cellular components than other seizure types. This deeper level of understanding may guide investigations into pathways most critical to target in future precision medicine efforts.

The Role of Astrocytes in Neuroprotection after Brain Stroke: Potential in Cell Therapy

Astrocytes are commonly involved in negative responses through their hyperreactivity and glial scar formation in excitotoxic and/or mechanical injuries. But, astrocytes are also specialized glial cells of the nervous system that perform multiple homeostatic functions for the survival and maintenance of the neurovascular unit. Astrocytes have neuroprotective, angiogenic, immunomodulatory, neurogenic, and antioxidant properties and modulate synaptic function. This makes them excellent candidates as a source of neuroprotection and neurorestoration in tissues affected by ischemia/reperfusion, when some of their deregulated genes can be controlled. Therefore, this review analyzes pro-survival responses of astrocytes that would allow their use in cell therapy strategies.

Targeting G protein-coupled receptor for pain management

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage. Great progress has been made in understanding the important roles of various G protein-coupled receptors in the regulation of pain transmission. However, many important questions remain uncertain about the precise signal transduction mechanisms. This review focuses opioid receptor and CXC receptor 4 on the effects and mechanisms of pain. Taken together, chemokines and their receptors are potential targets for the development of novel pain management and therapy.

SDF-1/CXCR4 Signaling Maintains Stemness Signature in Mouse Neural Stem/Progenitor Cells

SDF-1 and its primary receptor, CXCR4, are highly expressed in the embryonic central nervous system (CNS) and play a crucial role in brain architecture. Loss of SDF-1/CXCR4 signaling causes abnormal development of neural stem/progenitor cells (NSCs/NPCs) in the cerebellum, hippocampus, and cortex. However, the mechanism of SDF-1/CXCR4 axis in NSCs/NPCs regulation remains unknown. In this study, we found that elimination of SDF-1/CXCR4 transduction caused NSCs/NPCs to lose their stemness characteristics and to encounter neurogenic differentiation. Moreover, Notch and RE1 silencing transcription factor (REST) both play an essential role in NSCs/NPCs maintenance and neuronal differentiation and were dramatically downregulated following SDF-1/CXCR4 cascade inhibition. Finally, we demonstrated that the expression of achaete-scute homolog 1 (Ascl1), a proneural gene, and p27, an antiproliferative gene, were significantly increased after genetic elimination of SDF-1 alleles. Our results support that the loss of functional SDF-1/CXCR4 signaling pathway in NSCs/NPCs induces exit of cell cycle and promotes premature neural differentiation.

Psychoneuroimmunology of Early-Life Stress: The Hidden Wounds of Childhood Trauma?

The brain and the immune system are not fully formed at birth, but rather continue to mature in response to the postnatal environment. The two-way interaction between the brain and the immune system makes it possible for childhood psychosocial stressors to affect immune system development, which in turn can affect brain development and its long-term functioning. Drawing from experimental animal models and observational human studies, we propose that the psychoneuroimmunology of early-life stress can offer an innovative framework to understand and treat psychopathology linked to childhood trauma. Early-life stress predicts later inflammation, and there are striking analogies between the neurobiological correlates of early-life stress and of inflammation. Furthermore, there are overlapping trans-diagnostic patterns of association of childhood trauma and inflammation with clinical outcomes. These findings suggest new strategies to remediate the effect of childhood trauma before the onset of clinical symptoms, such as anti-inflammatory interventions and potentiation of adaptive immunity. Similar strategies might be used to ameliorate the unfavorable treatment response described in psychiatric patients with a history of childhood trauma.