Involvement of the neurotensin receptor-3 in the neurotensin-induced migration of human microglia

Human pluripotent stem cell (hPSC)-derived microglia for the study of brain disorders. A comprehensive review of existing protocols

Microglia, resident immune cells of the brain that originate from the yolk sac, play a critical role in maintaining brain homeostasis by monitoring and phagocytosing pathogens and cellular debris in the central nervous system (CNS). While they share characteristics with myeloid cells, they are distinct from macrophages. In response to injury, microglia release pro-inflammatory factors and contribute to brain homeostasis through activities such as synapse pruning and neurogenesis. To better understand their role in neurological disorders, the generation of in vitro models of human microglia has become essential. These models, derived from patient-specific induced pluripotent stem cells (iPSCs), provide a controlled environment to study the molecular and cellular mechanisms underlying microglia-mediated neuroinflammation and neurodegeneration. The incorporation or generation of microglia into three-dimensional (3D) organoid cultures provides a more physiologically relevant environment that offers further opportunities to study microglial dynamics and disease modeling. This review describes several protocols that have been recently developed for the generation of human-induced microglia. Importantly, it highlights the promise of these in vitro models in advancing our understanding of brain disorders and facilitating personalized drug screening.

Sortilin inhibition in microglial cells cannot alleviate ischemia and hypoxia-induced neuronal injury in co-culture

Sortilin is a single-pass type I transmembrane protein which can bind to various cargo proteins, regulating their surface location, secretion, or degradation in lysosomes. In our previous study, we found that sortilin can regulate progranulin expression by transporting it to lysosomes and reduce neuronal cell injury in hypoxia-ischemia, but the expression and function of sortilin in microglial cells during hypoxia-ischemia are unknown. The purpose of this study was to further investigate the function of sortilin in microglial cells and its effect on neuron cells. In rat BV2 microglial cells, sortilin was knocked down by lentivirus. After oxygen-glucose deprivation/reperfusion (OGD/R), expression of sortilin, progranulin (PGRN) and JNK pathway was detected by western blot, immunofluorescence was used to show the localization of PGRN, secretion of TNFα/IL-6 was measured by Elisa. Then co-culture microglial cells with neuron cells during hypoxia-ischemia and detected the neuron injury by CCK-8 and TUNEL. The expression of sortilin, mature and cleaved PGRN were all increased after OGD/R in microglial cells. Furthermore, sortilin inhibition accompany with less PGRN localization in lysosomes and more mature and less cleaved PGRN expression in microglial cells. Sortilin inhibition also can reduce the inflammatory response in microglial cells, but it does not alleviate neuronal injury in co-culture. This study demonstrated that sortilin can regulate the expression of PGRN and reduce the inflammatory response in microglial cells. However, only inhibiting sortilin in microglial cells did not have an impact on the survival of neurons during ischemia-hypoxia.

Mast Cells in Autism Spectrum Disorder-The Enigma to Be Solved?

Autism Spectrum Disorder (ASD) is a disturbance of neurodevelopment with a complicated pathogenesis and unidentified etiology. Many children with ASD have a history of "allergic symptoms", often in the absence of mast cell (MC)-positive tests. Activation of MCs by various stimuli may release molecules related to inflammation and neurotoxicity, contributing to the development of ASD. The aim of the present paper is to enrich the current knowledge on the relationship between MCs and ASD by discussing key molecules and immune pathways associated with MCs in the pathogenesis of autism. Cytokines, essential marker molecules for MC degranulation and therapeutic targets, are also highlighted. Understanding the relationship between ASD and the activation of MCs, as well as the involved molecules and interactions, are the main points contributing to solving the enigma. Key molecules, associated with MCs, may provide new insights to the discovery of drug targets for modeling inflammation in ASD.

Neurotensin and Neurotensin Receptors in Stress-related Disorders: Pathophysiology & Novel Drug Targets

Neurotensin (NT) is a 13-amino acid neuropeptide widely distributed in the CNS that has been involved in the pathophysiology of many neural and psychiatric disorders. There are three known neurotensin receptors (NTSRs), which mediate multiple actions, and form the neurotensinergic system in conjunction with NT. NTSR1 is the main mediator of NT, displaying effects in both the CNS and the periphery, while NTSR2 is mainly expressed in the brain and NTSR3 has a broader expression pattern. In this review, we bring together up-to-date studies showing an involvement of the neurotensinergic system in different aspects of the stress response and the main stress-related disorders, such as depression and anxiety, post-traumatic stress disorder (PTSD) and its associated symptoms, such as fear memory and maternal separation, ethanol addiction, and substance abuse. Emphasis is put on gene, mRNA, and protein alterations of NT and NTSRs, as well as behavioral and pharmacological studies, leading to evidence-based suggestions on the implicated regulating mechanisms as well as their therapeutic exploitation. Stress responses and anxiety involve mainly NTSR1, but also NTSR2 and NTSR3. NTSR1 and NTSR3 are primarily implicated in depression, while NTSR2 and secondarily NTSR1 in PTSD. NTSR1 is interrelated with substance and drug abuse and NTSR2 with fear memory, while all NTSRs seem to be implicated in ethanol consumption. Some of the actions of NT and NTSRs in these pathological settings may be driven through interactions between NT and corticotrophin releasing factor (CRF) in their regulatory contribution, as well as by NT's pro-inflammatory mediating actions.

Defining super-enhancers by highly ranked histone H4 multi-acetylation levels identifies transcription factors associated with glioblastoma stem-like properties

BACKGROUND

Super-enhancers (SEs), which activate genes involved in cell-type specificity, have mainly been defined as genomic regions with top-ranked enrichment(s) of histone H3 with acetylated K27 (H3K27ac) and/or transcription coactivator(s) including a bromodomain and extra-terminal domain (BET) family protein, BRD4. However, BRD4 preferentially binds to multi-acetylated histone H4, typically with acetylated K5 and K8 (H4K5acK8ac), leading us to hypothesize that SEs should be defined by high H4K5acK8ac enrichment at least as well as by that of H3K27ac.

RESULTS

Here, we conducted genome-wide profiling of H4K5acK8ac and H3K27ac, BRD4 binding, and the transcriptome by using a BET inhibitor, JQ1, in three human glial cell lines. When SEs were defined as having the top ranks for H4K5acK8ac or H3K27ac signal, 43% of H4K5acK8ac-ranked SEs were distinct from H3K27ac-ranked SEs in a glioblastoma stem-like cell (GSC) line. CRISPR-Cas9-mediated deletion of the H4K5acK8ac-preferred SEs associated with MYCN and NFIC decreased the stem-like properties in GSCs.

CONCLUSIONS

Collectively, our data highlights H4K5acK8ac's utility for identifying genes regulating cell-type specificity.

Sortilin inhibition treats multiple neurodegenerative lysosomal storage disorders

Lysosomal storage disorders (LSDs) are a genetically and clinically diverse group of diseases characterized by lysosomal dysfunction. Batten disease is a family of severe LSDs primarily impacting the central nervous system. Here we show that AF38469, a small molecule inhibitor of sortilin, improves lysosomal and glial pathology across multiple LSD models. Live-cell imaging and comparative transcriptomics demonstrates that the transcription factor EB (TFEB), an upstream regulator of lysosomal biogenesis, is activated upon treatment with AF38469. Utilizing CLN2 and CLN3 Batten disease mouse models, we performed a short-term efficacy study and show that treatment with AF38469 prevents the accumulation of lysosomal storage material and the development of neuroinflammation, key disease associated pathologies. Tremor phenotypes, an early behavioral phenotype in the CLN2 disease model, were also completely rescued. These findings reveal sortilin inhibition as a novel and highly efficacious therapeutic modality for the treatment of multiple forms of Batten disease.

The Neurobiological Underpinnings of Obsessive-Compulsive Symptoms in Psychosis, Translational Issues for Treatment-Resistant Schizophrenia

Almost 25% of schizophrenia patients suffer from obsessive-compulsive symptoms (OCS) considered a transdiagnostic clinical continuum. The presence of symptoms pertaining to both schizophrenia and obsessive-compulsive disorder (OCD) may complicate pharmacological treatment and could contribute to lack or poor response to the therapy. Despite the clinical relevance, no reviews have been recently published on the possible neurobiological underpinnings of this comorbidity, which is still unclear. An integrative view exploring this topic should take into account the following aspects: (i) the implication for glutamate, dopamine, and serotonin neurotransmission as demonstrated by genetic findings; (ii) the growing neuroimaging evidence of the common brain regions and dysfunctional circuits involved in both diseases; (iii) the pharmacological modulation of dopaminergic, serotoninergic, and glutamatergic systems as current therapeutic strategies in schizophrenia OCS; (iv) the recent discovery of midbrain dopamine neurons and dopamine D1- and D2-like receptors as orchestrating hubs in repetitive and psychotic behaviors; (v) the contribution of N-methyl-D-aspartate receptor subunits to both psychosis and OCD neurobiology. Finally, we discuss the potential role of the postsynaptic density as a structural and functional hub for multiple molecular signaling both in schizophrenia and OCD pathophysiology.

Neurotensin expression, regulation, and function during the ovulatory period in the mouse ovary†

The luteinizing hormone (LH) surge induces paracrine mediators within the ovarian follicle that promote ovulation. The present study explores neurotensin (NTS), a neuropeptide, as a potential ovulatory mediator in the mouse ovary. Ovaries and granulosa cells (GCs) were collected from immature 23-day-old pregnant mare serum gonadotropin primed mice before (0 h) and after administration of human chorionic gonadotropin (hCG; an LH analog) across the periovulatory period (4, 8, 12, and 24 h). In response to hCG, Nts expression rapidly increased 250-fold at 4 h, remained elevated until 8 h, and decreased until 24 h. Expression of Nts receptors for Ntsr1 remained unchanged across the periovulatory period, Ntsr2 was undetectable, whereas Sort1 expression (also called Ntsr3) gradually decreased in both the ovary and GCs after hCG administration. To better understand Nts regulation, inhibitors of the LH/CG signaling pathways were utilized. Our data revealed that hCG regulated Nts expression through the protein kinase A (PKA) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways. Additionally, epidermal-like-growth factor (EGF) receptor signaling also mediated Nts induction in GCs. To elucidate the role of NTS in the ovulatory process, we used a Nts silencing approach (si-Nts) followed by RNA-sequencing (RNA-seq). RNA-seq analysis of GCs collected after hCG with or without si-Nts identified and qPCR confirmed Ell2, Rsad2, Vps37a, and Smtnl2 as genes downstream of Nts. In summary, these findings demonstrate that hCG induces Nts and that Nts expression is mediated by PKA, p38MAPK, and EGF receptor signaling pathways. Additionally, NTS regulates several novel genes that could potentially impact the ovulatory process.

Msx1+ stem cells recruited by bioactive tissue engineering graft for bone regeneration

Critical-sized bone defects often lead to non-union and full-thickness defects of the calvarium specifically still present reconstructive challenges. In this study, we show that neurotrophic supplements induce robust in vitro expansion of mesenchymal stromal cells, and in situ transplantation of neurotrophic supplements-incorporated 3D-printed hydrogel grafts promote full-thickness regeneration of critical-sized bone defects. Single-cell RNA sequencing analysis reveals that a unique atlas of in situ stem/progenitor cells is generated during the calvarial bone healing in vivo. Notably, we find a local expansion of resident Msx1+ skeletal stem cells after transplantation of the in situ cell culture system. Moreover, the enhanced calvarial bone regeneration is accompanied by an increased endochondral ossification that closely correlates to the Msx1+ skeletal stem cells. Our findings illustrate the time-saving and regenerative efficacy of in situ cell culture systems targeting major cell subpopulations in vivo for rapid bone tissue regeneration.

Critical-sized bone defects still present clinical challenges. Here the authors show that transplantation of neurotrophic supplement-incorporated hydrogel grafts promote full-thickness regeneration of the calvarium and perform scRNA-seq to reveal contributing stem/progenitor cells, notably a resident Msx1+ skeletal stem cell population.

Sorting through the extensive and confusing roles of sortilin in metabolic disease

Sortilin is a post-Golgi trafficking receptor homologous to the yeast vacuolar protein sorting receptor 10 (VPS10). The VPS10 motif on sortilin is a 10-bladed β-propeller structure capable of binding more than 50 proteins, covering a wide range of biological functions including lipid and lipoprotein metabolism, neuronal growth and death, inflammation, and lysosomal degradation. Sortilin has a complex cellular trafficking itinerary, where it functions as a receptor in the trans-Golgi network, endosomes, secretory vesicles, multivesicular bodies, and at the cell surface. In addition, sortilin is associated with hypercholesterolemia, Alzheimer's disease, prion diseases, Parkinson's disease, and inflammation syndromes. The 1p13.3 locus containing SORT1, the gene encoding sortilin, carries the strongest association with LDL-C of all loci in human genome-wide association studies. However, the mechanism by which sortilin influences LDL-C is unclear. Here, we review the role sortilin plays in cardiovascular and metabolic diseases and describe in detail the large and often contradictory literature on the role of sortilin in the regulation of LDL-C levels.

In Vitro Methodologies to Study the Role of Advanced Glycation End Products (AGEs) in Neurodegeneration

Advanced glycation end products (AGEs) can be present in food or be endogenously produced in biological systems. Their formation has been associated with chronic neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and amyotrophic lateral sclerosis. The implication of AGEs in neurodegeneration is related to their ability to bind to AGE-specific receptors and the ability of their precursors to induce the so-called “dicarbonyl stress”, resulting in cross-linking and protein damage. However, the mode of action underlying their role in neurodegeneration remains unclear. While some research has been carried out in observational clinical studies, further in vitro studies may help elucidate these underlying modes of action. This review presents and discusses in vitro methodologies used in research on the potential role of AGEs in neuroinflammation and neurodegeneration. The overview reveals the main concepts linking AGEs to neurodegeneration, the current findings, and the available and advisable in vitro models to study their role. Moreover, the major questions regarding the role of AGEs in neurodegenerative diseases and the challenges and discrepancies in the research field are discussed.

Neurotensin receptor 2 is induced in astrocytes and brain endothelial cells in relation to neuroinflammation following pilocarpine-induced seizures in rats

Neurotensin (NT) acts as a primary neurotransmitter and neuromodulator in the CNS and has been involved in a number of CNS pathologies including epilepsy. NT mediates its central and peripheral effects by interacting with the NTSR1, NTSR2, and Sort1/NTSR3 receptor subtypes. To date, little is known about the precise expression of the NT receptors in brain neural cells and their regulation in pathology. In the present work, we studied the cellular distribution of the NTSR2 protein in the rat hippocampus and questioned whether its expression was modulated in conditions of neuroinflammation using a model of temporal lobe epilepsy induced by pilocarpine. This model is characterized by a rapid and intense inflammatory reaction with reactive gliosis in the hippocampus. We show that NTSR2 protein is expressed in hippocampal astrocytes and its expression increases together with astrocyte reactivity following induction of status epilepticus. NTSR2 immunoreactivity is also increased in astrocytes proximal to blood vessels and their end-feet, and in endothelial cells. Proinflammatory factors such as IL1β and LPS induced NTSR2 mRNA and protein in cultured astroglial cells. Antagonizing NTSR2 with SR142948A decreased NTSR2 expression as well as astroglial reactivity. Together, our results suggest that NTSR2 is implicated in astroglial and gliovascular inflammation and that targeting the NTSR2 receptor may open new avenues in the regulation of neuroinflammation in CNS diseases.

Neurotensin: a neuropeptide induced by hCG in the human and rat ovary during the periovulatory period†

Neurotensin (NTS) is a tridecapeptide that was first characterized as a neurotransmitter in neuronal cells. The present study examined ovarian NTS expression across the periovulatory period in the human and the rat. Women were recruited into this study and monitored by transvaginal ultrasound. The dominant follicle was surgically excised prior to the luteinizing hormone (LH) surge (preovulatory phase) or women were given 250 μg human chorionic gonadotropin (hCG) and dominant follicles collected 12-18 h after hCG (early ovulatory), 18-34 h (late ovulatory), and 44-70 h (postovulatory). NTS mRNA was massively induced during the early and late ovulatory stage in granulosa cells (GCs) (15 000 fold) and theca cells (700 fold). In the rat, hCG also induced Nts mRNA expression in intact ovaries and isolated GCs. In cultured granulosa-luteal cells (GLCs) from IVF patients, NTS expression was induced 6 h after hCG treatment, whereas in cultured rat GCs, NTS increased 4 h after hCG treatment. Cells treated with hCG signaling pathway inhibitors revealed that NTS expression is partially regulated in the human and rat GC by the epidermal-like growth factor pathway. Human GLC, and rat GCs also showed that Nts was regulated by the protein kinase A (PKA) pathway along with input from the phosphotidylinositol 3- kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways. The predominat NTS receptor present in human and rat GCs was SORT1, whereas NTSR1 and NTSR2 expression was very low. Based on NTS actions in other systems, we speculate that NTS may regulate crucial aspects of ovulation such as vascular permeability, inflammation, and cell migration.

The multifaceted role of sortilin/neurotensin receptor 3 in human cancer development

Sortilin (also known as neurotensin receptor 3) is a multitasking protein implicated in numerous pathophysiological processes, including cancer development, cardiovascular impairment, Alzheimer-type dementia, and depression. Although the definitive role of sortilin in human solid and hematological malignancies has been evidenced, few articles reviewed the task. The aim of the current review is to unravel the mechanisms by which sortilin controls oncogenicity and cancer progression; and also to summarize and discuss the original data obtained from international research laboratories on this topic. Questions on how sortilin is involving in the impairment of cell junctions, in exosomes composition and release, as well as in the regulation of epidermal growth factor receptor trafficking are also responded. In addition, we provide a special focus on the regulatory role of sortilin in signal transduction by either neurotrophins or neurotensin in normal and malignant cells. The relevance of sortilin with normal and cancer stem cells is also discussed. The last section provides a general overview of sortilin applications as a diagnostic and prognostic biomarker in the context of cancer detection. Finally, we comment on the future research aspects in which the field of cancer diagnosis, prognosis, and therapy might be developed.

Therapeutic approaches targeting the neurotensin receptors

Introduction: Neurotensin is a gut-brain peptide hormone, a 13 amino acid neuropeptide found in the central nervous system and in the GI tract. The neurotensinergic system is implicated in various physiological and pathological processes related to neuropsychiatric and metabolic machineries, cancer growth, food, and drug intake. NT mediates its functions through its two G protein-coupled receptors: neurotensin receptor 1 (NTS1/NTSR1) and neurotensin receptor 2 (NTS2/NTSR2). Over the past decade, the role of NTS3/NTSR3/sortilin has also gained importance in human pathologies. Several approaches have appeared dealing with the discovery of compounds able to modulate the functions of this neuropeptide through its receptors for therapeutic gain.Areas covered: The article provides an overview of over four decades of research and details the drug discovery approaches and patented strategies targeting NTSR in the past decade.Expert opinion: Neurotensin is an important neurotransmitter that enables crosstalk with various neurotransmitter and neuroendocrine systems. While significant efforts have been made that have led to selective agonists and antagonists with promising in vitro and in vivo activities, the therapeutic potential of compounds targeting the neurotensinergic system is still to be fully harnessed for successful clinical translation of compounds for the treatment of several pathologies.

Neurotensin pathway in digestive cancers and clinical applications: an overview

Initially, NEUROTENSIN (NTS) has been shown to play physiological and biological functions as a neuro-transmitter/modulator in the central nervous system and as an endocrine factor in the periphery, through its binding to two kinds of receptors: NTSR1 and 2 (G protein-coupled receptors) and NTSR3/sortilin (a vacuolar protein-sorting 10-domain receptor). NTS also plays oncogenic roles in many types of cancer, including digestive cancers. In tumor tissues, NTS and NTSR1 expression is higher than in healthy ones and is associated with poor prognosis. NTS and NTRS1 promote cancer progression and play key functions in metastatic processes; they modulate several signaling pathways and they contribute to changes in the tumor microenvironment. Conversely, NTRS2 involvement in digestive cancers is poorly understood. Discovered for mediating NTS biological effects, sortilin recently emerged as a promising target as its expression was found to be increased in various types of cancers. Because it can be secreted, a soluble form of sortilin (sSortilin) appears as a new serum biomarker which, on the basis of recent studies, promises to be useful in both the diagnosis and tumor progression monitoring. More precisely, it appears that soluble sortilin can be associated with other receptors like TRKB. These associations occur in exosomes and trigger the aggressiveness of cancers like glioblastoma, leading to the concept of a possible composite theranostic biomarker. This review summarizes the oncogenic roles of the NTS signaling pathways in digestive cancers and discusses their emergence as promising early diagnostic and/or prognostic biomarkers and therapeutic targets.

Comparative analysis of human microglial models for studies of HIV replication and pathogenesis

Background

HIV associated neurocognitive disorders cause significant morbidity and mortality despite the advent of highly active antiretroviral therapy. A deeper understanding of fundamental mechanisms underlying HIV infection and pathogenesis in the central nervous system is warranted. Microglia are resident myeloid cells of the brain that are readily infected by HIV and may constitute a CNS reservoir. We evaluated two microglial model cell lines (C20, HMC3) and two sources of primary cell-derived microglia (monocyte-derived microglia [MMG] and induced pluripotent stem cell-derived microglia [iPSC-MG]) as potential model systems for studying HIV-microglia interactions.

Results

All four microglial model cells expressed typical myeloid markers with the exception of low or absent CD45 and CD11b expression by C20 and HMC3, and all four expressed the microglia-specific markers P2RY12 and TMEM119. Marked differences were observed upon gene expression profiling, however, indicating that MMG and iPSC-MG cluster closely together with primary human microglial cells, while C20 and HMC3 were similar to each other but very different from primary microglia. Expression of HIV-relevant genes also revealed important differences, with iPSC-MG and MMG expressing relevant genes at levels more closely resembling primary microglia. iPSC-MG and MMG were readily infected with R5-tropic HIV, while C20 and HMC3 lack CD4 and require pseudotyping for infection. Despite many similarities, HIV replication dynamics and HIV-1 particle capture by Siglec-1 differed markedly between the MMG and iPSC-MG.

Conclusions

MMG and iPSC-MG appear to be viable microglial models that are susceptible to HIV infection and bear more similarities to authentic microglia than two transformed microglia cell lines. The observed differences in HIV replication and particle capture between MMG and iPSC-MG warrant further study.

Neurotensins and their therapeutic potential: research field study

The natural tridecapeptide neurotensin has been emerged as a promising therapeutic scaffold for the treatment of neurological diseases and cancer. In this work, we aimed to identify the top 100 most cited original research papers as well as recent key studies related to neurotensins. The Web of Science Core Collection database was searched and the retrieved research articles were analyzed by using the VOSviewer software. The most cited original articles were published between 1973 and 2013. The top-cited article was by Carraway and Leeman reporting the discovery of neurotensin in 1973. The highly cited terms were associated with hypotension and angiotensin-converting-enzyme. The conducted analysis reveals the therapeutic potentials of neurotensin, and further impactful research toward its clinical development is warrantied.

Neurotensin Enhances Locomotor Activity and Arousal and Inhibits Melanin-Concentrating Hormone Signaling

BACKGROUND

Hypothalamic neurotensin (Nts)-secreting neurons regulate fundamental physiological processes including metabolism and feeding. However, the role of Nts in modulation of locomotor activity, sleep, and arousal is unclear. We previously identified and characterized Nts neurons in the zebrafish hypothalamus.

MATERIALS AND METHODS

In order to study the role of Nts, nts mutant (nts-/-), and overexpressing zebrafish were generated.

RESULTS

The expression of both nts mRNA and Nts protein was reduced during the night in wild-type zebrafish. Behavioral assays revealed that locomotor activity was decreased during both day and night, while sleep was increased exclusively during the nighttime in nts-/- larvae. Likewise, inducible overexpression of Nts increased arousal in hsp70:Gal4/uas:Nts larvae. Furthermore, the behavioral response to light-to-dark transitions was reduced in nts-/- larvae. In order to elucidate potential contenders that may mediate Nts action on these behaviors, we profiled the transcriptome of 6 dpf nts-/- larvae. Among other genes, the expression levels of melanin-concentrating hormone receptor 1b were increased in nts-/- larvae. Furthermore, a portion of promelanin-concentrating hormone 1 (pmch1) and pmch2 neurons expressed the nts receptor. In addition, expression of the the two zebrafish melanin-concentrating hormone (Mch) orthologs, Mch1 and Mch2, was increased in nts-/- larvae.

CONCLUSION

These results show that the Nts and Mch systems interact and modulate locomotor activity and arousal.

Gender Related Changes in Gene Expression Induced by Valproic Acid in A Mouse Model of Autism and the Correction by S-adenosyl Methionine. Does It Explain the Gender Differences in Autistic Like Behavior?

In previous studies we produced autism like behavioral changes in mice by Valproic acid (VPA) with significant differences between genders. S-adenosine methionine (SAM) prevented the autism like behavior in both genders. The expression of 770 genes of pathways involved in neurophysiology and neuropathology was studied in the prefrontal cortex of 60 days old male and female mice using the NanoString nCounter. In females, VPA induced statistically significant changes in the expression of 146 genes; 71 genes were upregulated and 75 downregulated. In males, VPA changed the expression of only 19 genes, 16 were upregulated and 3 downregulated. Eight genes were similarly changed in both genders. When considering only the genes that were changed by at least 50%, VPA changed the expression of 15 genes in females and 3 in males. Only Nts was similarly downregulated in both genders. SAM normalized the expression of most changed genes in both genders. We presume that genes that are involved in autism like behavior in our model were similarly changed in both genders and corrected by SAM. The behavioral and other differences between genders may be related to genes that were differently affected by VPA in males and females and/or differently affected by SAM.

IL-37 is increased in brains of children with autism spectrum disorder and inhibits human microglia stimulated by neurotensin

Autism spectrum disorder (ASD) does not have a distinct pathogenesis or effective treatment. Increasing evidence supports the presence of immune dysfunction and inflammation in the brains of children with ASD. In this report, we present data that gene expression of the antiinflammatory cytokine IL-37, as well as of the proinflammatory cytokines IL-18 and TNF, is increased in the amygdala and dorsolateral prefrontal cortex of children with ASD as compared to non-ASD controls. Gene expression of IL-18R, which is a receptor for both IL-18 and IL-37, is also increased in the same brain areas of children with ASD. Interestingly, gene expression of the NTR3/sortilin receptor is reduced in the amygdala and dorsolateral prefrontal cortex. Pretreatment of cultured human microglia from normal adult brains with human recombinant IL-37 (1 to 100 ng/mL) inhibits neurotensin (NT)-stimulated secretion and gene expression of IL-1β and CXCL8. Another key finding is that NT, as well as the proinflammatory cytokines IL-1β and TNF increase IL-37 gene expression in cultured human microglia. The data presented here highlight the connection between inflammation and ASD, supporting the development of IL-37 as a potential therapeutic agent of ASD.

Inflammatory and Neuropathic Gene Expression Signatures of Chemotherapy-Induced Neuropathy Induced by Vincristine, Cisplatin, and Oxaliplatin in C57BL/6J Mice

Vincristine, oxaliplatin, and cisplatin are commonly prescribed chemotherapeutic agents for the treatment of many tumors. However, a main side effect is chemotherapy-induced peripheral neuropathy (CIPN), which may lead to changes in chemotherapeutic treatment. Although symptoms associated with CIPN are recapitulated by mouse models, there is limited knowledge of how these drugs affect the expression of genes in sensory neurons. The present study carried out a transcriptomic analysis of dorsal root ganglia following vincristine, oxaliplatin, and cisplatin treatment with a view to gain insight into the comparative pathophysiological mechanisms of CIPN. RNA-Seq revealed 368, 295, and 256 differential expressed genes induced by treatment with vincristine, oxaliplatin, and cisplatin, respectively, and only 5 shared genes were dysregulated in all 3 groups. Cell type enrichment analysis and gene set enrichment analysis showed predominant effects on genes associated with the immune system after treatment with vincristine, while oxaliplatin treatment affected mainly neuronal genes. Treatment with cisplatin resulted in a mixed gene expression signature. PERSPECTIVE: These results provide insight into the recruitment of immune responses to dorsal root ganglia and indicate enhanced neuroinflammatory processes following administration of vincristine, oxaliplatin, and cisplatin. These gene expression signatures may provide insight into novel drug targets for treatment of CIPN.

The Involvement of Sortilin/NTSR3 in Depression as the Progenitor of Spadin and Its Role in the Membrane Expression of TREK-1

The molecular identification of sortilin, also called neurotensin receptor-3, from three different biochemical approaches already predicted the involvement of the protein in numerous biological and cellular functions. The first important observation was that sortilin is synthesized as a precursor that is converted to a mature protein after cleavage by the protein convertase furin in late Golgi compartments. This maturation leads to the formation of a 44 amino acid peptide, the propeptide (PE). The release of this peptide when matured sortilin reached the plasma membrane remained to be demonstrated. Sortilin has been also shown to be shedded by matrix metalloproteases releasing a large extracellular fragment identified as soluble sortilin. Therefore, sortilin has been shown to interact with several proteins and receptors confirming its role in the sorting of cellular components to the plasma membrane and/or to the lysosomal pathway. Interestingly, sortilin physically interacts with the two pore domain potassium channel TREK-1 and the PE as well as its synthetic analog spadin is able to block the activation of TREK-1 highlighting their role in the depression pathology. The present review describes the advance of research that led to these results and how both the soluble form of sortilin and the sortilin-derived PE have been detected in human serum and whose levels are affected in patients with major depressive disorder (MDD). The use of spadin as an antidepressant and the further role of soluble sortilin and of sortilin-derived PE as potential biomarkers during depression statement and/or remission of the pathology are considered and discussed in this review.

Regulatory Roles of Sortilin and SorLA in Immune-Related Processes

Sortilin, also known as Neurotensin Receptor-3, and the sorting-related receptor with type-A repeats (SorLA) are both members of the Vps10p domain receptor family. Initially identified in CNS cells, they are expressed in various other cell types where they exert multiple functions. Although mostly studied for its involvement in Alzheimer’s disease, SorLA has recently been shown to be implicated in immune response by regulating IL-6-mediated signaling, as well as driving monocyte migration. Sortilin has been shown to act as a receptor, as a co-receptor and as an intra- and extracellular trafficking regulator. In the last two decades, deregulation of sortilin has been demonstrated to be involved in many human pathophysiologies, including neurodegenerative disorders (Alzheimer and Parkinson diseases), type 2 diabetes and obesity, cancer, and cardiovascular pathologies such as atherosclerosis. Several studies highlighted different functions of sortilin in the immune system, notably in microglia, pro-inflammatory cytokine regulation, phagosome fusion and pathogen clearance. In this review, we will analyze the multiple roles of sortilin and SorLA in the human immune system and how their deregulation may be involved in disease development.

Potential roles of neurotensin on cognition in conditions of obese-insulin resistance

Neurotensin is an endogenous tridecapeptide that can be found in both central and peripheral nervous systems. Under normal physiological conditions, neurotensin is involved in the regulation of pain, body temperature, physical activity, appetite as well as learning and memory. In addition, it plays an important role in fat metabolism. Previous studies have demonstrated that alterations of neurotensin levels were associated with several neuropathological conditions such as Alzheimer's disease, mood disorders, and obesity associated eating disorders. Obesity has been shown to be associated with low-grade systemic inflammation, brain inflammation, and cognitive decline. Several pieces of evidence suggest that neurotensin might play a role in cognitive decline following obesity. However, the underlying mechanisms of neurotensin on cognition under obese-insulin resistant condition are still unclear. In this review, the current available evidence from in vitro, in vivo and clinical studies regarding the role of neurotensin in the physiological condition and obesity in association with cognition are comprehensively summarized and discussed. The studies which report controversial findings regarding these issues are also presented and discussed.

Fighting against depression with TREK-1 blockers: Past and future. A focus on spadin

Depression is a devastating mood disorder and a leading cause of disability worldwide. Depression affects approximately one in five individuals in the world and represents heavy economic and social burdens. The neurobiological mechanisms of depression are not fully understood, but evidence highlights the role of monoamine neurotransmitter balance. Several antidepressants (ADs) are marketed to treat depression and related mood disorders. However, despite their efficacy, they remain nonspecific and unsafe because they trigger serious adverse effects. Therefore, developing new molecules for new targets in depression has become a real necessity. Eight years ago, spadin was described as a natural peptide with AD properties. This 17-amino acid peptide blocks TREK-1 channels, an original target in depression. Compared to the classical AD drugs such as fluoxetine, which requires 3-4 weeks for the AD effect to manifest, spadin acts rapidly within only 4 days of treatment. The AD properties are associated with increased neurogenesis and synaptogenesis in the brain. Despite the advantages of this fast-acting AD, the in vivo stability is weak and does not last for >7 h. The present review summarizes different strategies such as retro-inverso strategy, cyclization, and shortening the spadin sequence that has led to the development and optimization of spadin as an AD. Shortened spadin analogs present increased inhibition potency for TREK-1, an improved AD activity, and prolonged in vivo bioavailability. Finally, we also discuss about other inhibitors of TREK-1 channels with a proven efficacy in treating depression in the clinic, such as fluoxetine.

The human microglial HMC3 cell line: where do we stand? A systematic literature review

Microglia, unique myeloid cells residing in the brain parenchyma, represent the first line of immune defense within the central nervous system. In addition to their immune functions, microglial cells play an important role in other cerebral processes, including the regulation of synaptic architecture and neurogenesis. Chronic microglial activation is regarded as detrimental, and it is considered a pathogenic mechanism common to several neurological disorders. Microglial activation and function have been extensively studied in rodent experimental models, whereas the characterization of human cells has been limited due to the restricted availability of primary sources of human microglia. To overcome this problem, human immortalized microglial cell lines have been developed. The human microglial clone 3 cell line, HMC3, was established in 1995, through SV40-dependent immortalization of human embryonic microglial cells. It has been recently authenticated by the American Type Culture Collection (ATCC®) and distributed under the name of HMC3 (ATCC®CRL-3304). The HMC3 cells have been used in six research studies, two of which also indicated by ATCC® as reference articles. However, a more accurate literature revision suggests that clone 3 was initially distributed under the name of CHME3. In this regard, several studies have been published, thus contributing to a more extensive characterization of this cell line. Remarkably, the same cell line has been used in different laboratories with other denominations, i.e., CHME-5 cells and C13-NJ cells. In view of the fact that "being now authenticated by ATCC®" may imply a wider distribution of the cells, we aimed at reviewing data obtained with the human microglia cell line clone 3, making the readers aware of this complicated nomenclature. In addition, we also included original data, generated in our laboratory with the HMC3 (ATCC®CRL-3304) cells, providing information on the current state of the culture together with supplementary details on the culturing procedures to obtain and maintain viable cells.

An Overview of in vitro Methods to Study Microglia

Neuroinflammation is a common feature in neurodegenerative diseases and strategies to modulate neuroinflammatory processes are increasingly considered as therapeutic options. In such strategies, glia cells rather than neurons represent the cellular targets. Microglia, the resident macrophages of the central nervous system, are principal players in neuroinflammation and detailed cellular biological knowledge of this particular cell type is therefore of pivotal importance. The last decade has shed new light on the origin, characteristics and functions of microglia, underlining the need for specific in vitro methodology to study these cells in detail. In this review we provide a comprehensive overview of existing methodology such as cell lines, stem cell-derived microglia and primary dissociated cell cultures, as well as discuss recent developments. As there is no in vitro method available yet that recapitulates all hallmarks of adult homeostatic microglia, we also discuss the advantages and limitations of existing models across different species.

New extracellular factors in glioblastoma multiforme development: neurotensin, growth differentiation factor-15, sphingosine-1-phosphate and cytomegalovirus infection

Recent years have seen considerable progress in understanding the biochemistry of cancer. For example, more significance is now assigned to the tumor microenvironment, especially with regard to intercellular signaling in the tumor niche which depends on many factors secreted by tumor cells. In addition, great progress has been made in understanding the influence of factors such as neurotensin, growth differentiation factor-15 (GDF-15), sphingosine-1-phosphate (S1P), and infection with cytomegalovirus (CMV) on the 'hallmarks of cancer' in glioblastoma multiforme. Therefore, in the present work we describe the influence of these factors on the proliferation and apoptosis of neoplastic cells, cancer stem cells, angiogenesis, migration and invasion, and cancer immune evasion in a glioblastoma multiforme tumor. In particular, we discuss the effect of neurotensin, GDF-15, S1P (including the drug FTY720), and infection with CMV on tumor-associated macrophages (TAM), microglial cells, neutrophil and regulatory T cells (T_reg), on the tumor microenvironment. In order to better understand the role of the aforementioned factors in tumoral processes, we outline the latest models of intratumoral heterogeneity in glioblastoma multiforme. Based on the most recent reports, we discuss the problems of multi-drug therapy in treating glioblastoma multiforme.

Neurotensin Receptor 3/Sortilin Contributes to Tumorigenesis of Neuroendocrine Tumors Through Augmentation of Cell Adhesion and Migration

Neurotensin (NTS), a 13–amino acid peptide which is distributed predominantly along gastrointestinal tract, has multiple physiologic and pathologic functions, and its effects are mediated by three distinct NTS receptors (NTSRs). Overexpression and activation of NTS signaling components, especially NTS and/or NTSR1, are closely linked with cancer progression and metastasis in various types of cancers including neuroendocrine tumors (NETs). Although deregulation of NTSR3/sortilin has been implicated in a variety of human diseases, the expression and role of NTSR3/sortilin in NETs have not been elucidated. In this study, we investigated the expression and oncogenic effect of NTSR3/sortilin in NETs. Increased protein levels of NTSR3/sortilin were noted in the majority of human clinical NETs (n = 21) by immunohistochemical analyses compared with normal tissues (n = 12). Expression of NTS and NTSR3/sortilin was also noted in all tested NET cell lines. In addition, small interfering RNA–mediated knockdown of NTSR3/sortilin decreased cell number without alteration of cell cycle progression and apoptosis induction in NET cell lines BON and QGP-1. Moreover, silencing of NTSR3/sortilin significantly suppressed cell adhesion and cell migration with inhibition of focal adhesion kinase and Src phosphorylation in the NET cells. Our results demonstrate increased expression of NTSR3/sortilin in NET patient tissues and a critical role of NTSR3/sortilin on NET cell adhesion and migration suggesting that NTSR3/sortilin contributes to NET tumorigenesis.

Immortalization of primary microglia: a new platform to study HIV regulation in the central nervous system

The major reservoirs for HIV in the CNS are in the microglia, perivascular macrophages, and to a lesser extent, astrocytes. To study the molecular events controlling HIV expression in the microglia, we developed a reliable and robust method to immortalize microglial cells from primary glia from fresh CNS tissues and commercially available frozen glial cells. Primary human cells, including cells obtained from adult brain tissue, were transformed with lentiviral vectors expressing SV40 T antigen or a combination of SVR40 T antigen and hTERT. The immortalized cells have microglia-like morphology and express key microglial surface markers including CD11b, TGFβR, and P2RY12. Importantly, these cells were confirmed to be of human origin by sequencing. The RNA expression profiles identified by RNA-seq are also characteristic of microglial cells. Furthermore, the cells demonstrate the expected migratory and phagocytic activity, and the capacity to mount an inflammatory response characteristic of primary microglia. The immortalization method has also been successfully applied to a wide range of microglia from other species (macaque, rat, and mouse). To investigate different aspects of HIV molecular regulation in CNS, the cells have been superinfected with HIV reporter viruses and latently infected clones have been selected that reactive HIV in response to inflammatory signals. The cell lines we have developed and rigorously characterized will provide an invaluable resource for the study of HIV infection in microglial cells as well as studies of microglial cell function.

Focal Adhesion Kinase-Dependent Role of the Soluble Form of Neurotensin Receptor-3/Sortilin in Colorectal Cancer Cell Dissociation

The aim of the present review is to unravel the mechanisms of action of the soluble form of the neurotensin (NT) receptor-3 (NTSR3), also called Sortilin, in numerous physiopathological processes including cancer development, cardiovascular diseases and depression. Sortilin/NTSR3 is a transmembrane protein thought to exert multiple functions both intracellularly and at the level of the plasma membrane. The Sortilin/NTSR3 extracellular domain is released by shedding from all the cells expressing the protein. Although the existence of the soluble form of Sortilin/NTSR3 (sSortilin/NTSR3) has been evidenced for more than 10 years, the studies focusing on the role of this soluble protein at the mechanistic level remain rare. Numerous cancer cells, including colonic cancer cells, express the receptor family of neurotensin (NT), and particularly Sortilin/NTSR3. This review aims to summarize the functional role of sSortilin/NTSR3 characterized in the colonic cancer cell line HT29. This includes mechanisms involving signaling cascades through focal adhesion kinase (FAK), a key pathway leading to the weakening of cell-cell and cell-extracellular matrix adhesions, a series of events which could be responsible for cancer metastasis. Finally, some future approaches targeting the release of sNTSR3 through the inhibition of matrix metalloproteases (MMPs) are suggested.

Phosphoinositide 3-kinase γ ties chemoattractant- and adrenergic control of microglial motility

Microglial motility is tightly controlled by multitude of agonistic and antagonistic factors. Chemoattractants, released after infection or damage of the brain, provoke directed migration of microglia to the pathogenic incident. In contrast, noradrenaline and other stress hormones have been shown to suppress microglial movement. Here we asked for the signaling reactions involved in the positive and negative control of microglial motility. Using pharmacological and genetic approaches we identified the lipid kinase activity of phosphoinositide 3-kinase species γ (PI3Kγ) as an essential mediator of microglial migration provoked by the complement component C5a and other chemoattractants. Inhibition of PI3Kγ lipid kinase activity by protein kinase A was disclosed as mechanism causing suppression of microglial migration by noradrenaline. Together these data characterize PI3Kγ as a nodal point in the control of microglial motility.

Production and Characterization of a Novel Monoclonal Antibody Against Human Sortilin

Sortilin, as a member of Vps10p-domain sorting receptor family, is overexpressed in a number of malignancies, including ovarian carcinoma. Antibodies against sortilin may contribute to further clarification of sortilin functional activities in signal transduction, intracellular sorting of proteins, and endocytosis. The aim of this study was to produce a monoclonal antibody against a synthetic peptide derived from extracellular N-terminal region of sortilin to be used as a tool for investigating sortilin characteristics in ovarian carcinoma. A synthetic peptide derived from the last 50 amino acids of extracellular domain of sortilin protein was selected and conjugated to keyhole limpet hemocyanin and used to immunize mice. The anti-sortilin monoclonal antibody (MAb), clone 2D8, was purified from supernatant of final hybridoma clone using peptide-affinity chromatography column. Reactivity of antibody with the immunizing peptide was assessed in ELISA. Furthermore, flow cytometry and Western blot analyses were used to investigate the reactivity of antibody with its target in a panel of ovarian carcinoma cell lines or tissues. MAb 2D8 was able to recognize the coated immunizing peptide in ELISA and detect its protein target, sortilin, in flow cytometry and Western blot analyses. The achieved data suggest that the developed monoclonal antibody may be applicable as a research tool for detection of sortilin protein in Western blot as well as flow cytometry tests.

Neurotensin stimulates sortilin and mTOR in human microglia inhibitable by methoxyluteolin, a potential therapeutic target for autism

We had reported elevated serum levels of the peptide neurotensin (NT) in children with autism spectrum disorders (ASD). Here, we show that NT stimulates primary human microglia, the resident immune cells of the brain, and the immortalized cell line of human microglia-SV40. NT (10 nM) increases the gene expression and release (P < 0.001) of the proinflammatory cytokine IL-1β and chemokine (C-X-C motif) ligand 8 (CXCL8), chemokine (C-C motif) ligand 2 (CCL2), and CCL5 from human microglia. NT also stimulates proliferation (P < 0.05) of microglia-SV40. Microglia express only the receptor 3 (NTR3)/sortilin and not the NTR1 or NTR2. The use of siRNA to target sortilin reduces (P < 0.001) the NT-stimulated cytokine and chemokine gene expression and release from human microglia. Stimulation with NT (10 nM) increases the gene expression of sortilin (P < 0.0001) and causes the receptor to be translocated from the cytoplasm to the cell surface, and to be secreted extracellularly. Our findings also show increased levels of sortilin (P < 0.0001) in the serum from children with ASD (n = 36), compared with healthy controls (n = 20). NT stimulation of microglia-SV40 causes activation of the mammalian target of rapamycin (mTOR) signaling kinase, as shown by phosphorylation of its substrates and inhibition of these responses by drugs that prevent mTOR activation. NT-stimulated responses are inhibited by the flavonoid methoxyluteolin (0.1-1 μM). The data provide a link between sortilin and the pathological findings of microglia and inflammation of the brain in ASD. Thus, inhibition of this pathway using methoxyluteolin could provide an effective treatment of ASD.

Organ of Corti explants direct tonotopically graded morphology of spiral ganglion neurons in vitro

The spiral ganglion is a compelling model system to examine how morphological form contributes to sensory function. While the ganglion is composed mainly of a single class of type I neurons that make simple one-to-one connections with inner hair cell sensory receptors, it has an elaborate overall morphological design. Specific features, such as soma size and axon outgrowth, are graded along the spiral contour of the cochlea. To begin to understand the interplay between different regulators of neuronal morphology, we cocultured neuron explants with peripheral target tissues removed from distinct cochlear locations. Interestingly, these "hair cell microisolates" were capable of both increasing and decreasing neuronal somata size, without adversely affecting survival. Moreover, axon characteristics elaborated de novo by the primary afferents in culture were systematically regulated by the sensory endorgan. Apparent peripheral nervous system (PNS)-like and central nervous system (CNS)-like axonal profiles were established in our cocultures allowing an analysis of putative PNS/CNS axon length ratios. As predicted from the in vivo organization, PNS-like axon bundles elaborated by apical cocultures were longer than their basal counterparts and this phenotype was methodically altered when neuron explants were cocultured with microisolates from disparate cochlear regions. Thus, location-dependent signals within the organ of Corti may set the "address" of neurons within the spiral ganglion, allowing them to elaborate the appropriate tonotopically associated morphological features in order to carry out their signaling function. J. Comp. Neurol. 524:2182-2207, 2016. © 2015 Wiley Periodicals, Inc.

Atopic diseases and inflammation of the brain in the pathogenesis of autism spectrum disorders

Autism spectrum disorders (ASDs) affect as many as 1 in 45 children and are characterized by deficits in sociability and communication, as well as stereotypic movements. Many children also show severe anxiety. The lack of distinct pathogenesis and reliable biomarkers hampers the development of effective treatments. As a result, most children with ASD are prescribed psychopharmacologic agents that do not address the core symptoms of ASD. Autoantibodies against brain epitopes in mothers of children with ASD and many such children strongly correlate with allergic symptoms and indicate an aberrant immune response, as well as disruption of the blood-brain barrier (BBB). Recent epidemiological studies have shown a strong statistical correlation between risk for ASD and either maternal or infantile atopic diseases, such as asthma, eczema, food allergies and food intolerance, all of which involve activation of mast cells (MCs). These unique tissue immune cells are located perivascularly in all tissues, including the thalamus and hypothalamus, which regulate emotions. MC-derived inflammatory and vasoactive mediators increase BBB permeability. Expression of the inflammatory molecules interleukin (IL-1β), IL-6, 1 L-17 and tumor necrosis factor (TNF) is increased in the brain, cerebrospinal fluid and serum of some patients with ASD, while NF-kB is activated in brain samples and stimulated peripheral blood immune cells of other patients; however, these molecules are not specific. Instead the peptide neurotensin is uniquely elevated in the serum of children with ASD, as is corticotropin-releasing hormone, secreted from the hypothalamus under stress. Both peptides trigger MC to release IL-6 and TNF, which in turn, stimulate microglia proliferation and activation, leading to disruption of neuronal connectivity. MC-derived IL-6 and TGFβ induce maturation of Th17 cells and MCs also secrete IL-17, which is increased in ASD. Serum IL-6 and TNF may define an ASD subgroup that benefits most from treatment with the natural flavonoid luteolin. Atopic diseases may create a phenotype susceptible to ASD and formulations targeting focal inflammation of the brain could have great promise in the treatment of ASD.

Differential regulation of macrophage phenotype by mature and pro-nerve growth factor

To characterize the role of neurotrophin receptors on macrophages, we investigated the ability of nerve growth factor (NGF) and its precursor, proNGF, to regulate human macrophage phenotype. The p75 neurotrophin receptor (p75(NTR)) and TrkA were concentrated within overlapping domains on membrane ruffles. NGF stimulation of macrophages increased membrane ruffling, calcium spiking, phagocytosis and growth factor secretion. In contrast, proNGF induced podosome formation, increased migration, suppressed calcium spikes and increased neurotoxin secretion. These results demonstrate opposing roles of NGF and proNGF in macrophage regulation providing new avenues for pharmacological intervention during neuroinflammation.

Mast cells, brain inflammation and autism

Increasing evidence indicates that brain inflammation is involved in the pathogenesis of neuropsychiatric diseases. Mast cells (MCs) are located perivascularly close to neurons and microglia, primarily in the leptomeninges, thalamus, hypothalamus and especially the median eminence. Corticotropin-releasing factor (CRF) is secreted from the hypothalamus under stress and, together with neurotensin (NT), can stimulate brain MCs to release inflammatory and neurotoxic mediators that disrupt the blood-brain barrier (BBB), stimulate microglia and cause focal inflammation. CRF and NT synergistically stimulate MCs and increase vascular permeability; these peptides can also induce each other׳s surface receptors on MCs leading to autocrine and paracrine effects. As a result, brain MCs may be involved in the pathogenesis of "brain fog," headaches, and autism spectrum disorders (ASDs), which worsen with stress. CRF and NT are significantly increased in serum of ASD children compared to normotypic controls further strengthening their role in the pathogenesis of autism. There are no clinically affective treatments for the core symptoms of ASDs, but pilot clinical trials using natural-antioxidant and anti-inflammatory molecules reported statistically significant benefit.

Hypothalamic leptin-neurotensin-hypocretin neuronal networks in zebrafish

Neurotensin (NTS) is a 13 amino acid neuropeptide that is expressed in the hypothalamus. In mammals, NTS-producing neurons that express leptin receptor (LepRb) regulate the function of hypocretin/orexin (HCRT) and dopamine neurons. Thus, the hypothalamic leptin-NTS-HCRT neuronal network orchestrates key homeostatic output, including sleep, feeding, and reward. However, the intricate mechanisms of the circuitry and the unique role of NTS-expressing neurons remain unclear. We studied the NTS neuronal networks in zebrafish and cloned the genes encoding the NTS neuropeptide and receptor (NTSR). Similar to mammals, the ligand is expressed primarily in the hypothalamus, while the receptor is expressed widely throughout the brain in zebrafish. A portion of hypothalamic nts-expressing neurons are inhibitory and some coexpress leptin receptor (lepR1). As in mammals, NTS and HCRT neurons are localized adjacently in the hypothalamus. To track the development and axonal projection of NTS neurons, the NTS promoter was isolated. Transgenesis and double labeling of NTS and HCRT neurons showed that NTS axons project toward HCRT neurons, some of which express ntsr. Moreover, another target of NTS neurons is ntsr-expressing dopaminergeric neurons. These findings suggest structural circuitry between leptin, NTS, and hypocretinergic or dopaminergic neurons and establish the zebrafish as a model to study the role of these neuronal circuits in the regulation of feeding, sleep, and reward.

Elevated serum neurotensin and CRH levels in children with autistic spectrum disorders and tail-chasing Bull Terriers with a phenotype similar to autism

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by defects in communication and social interactions, as well as stereotypic behaviors. Symptoms typically worsen with anxiety and stress. ASD occur in early childhood, often present with regression and have a prevalence of 1 out of 68 children. The lack of distinct pathogenesis or any objective biomarkers or reliable animal models hampers our understanding and treatment of ASD. Neurotensin (NT) and corticotropin-releasing hormone (CRH) are secreted under stress in various tissues, and have proinflammatory actions. We had previously shown that NT augments the ability of CRH to increase mast cell (MC)-dependent skin vascular permeability in rodents. CRH also induced NT receptor gene and protein expression in MCs, which have been implicated in ASD. Here we report that serum of ASD children (4-10 years old) has significantly higher NT and CRH levels as compared with normotypic controls. Moreover, there is a statistically significant correlation between the number of children with gastrointestinal symptoms and high serum NT levels. In Bull Terriers that exhibit a behavioral phenotype similar to the clinical presentation of ASD, NT and CRH levels are also significantly elevated, as compared with unaffected dogs of the same breed. Further investigation of serum NT and CRH, as well as characterization of this putative canine breed could provide useful insights into the pathogenesis, diagnosis and treatment of ASD.

Pro-neurotrophins, sortilin, and nociception

Nerve growth factor (NGF) signaling is important in the development and functional maintenance of nociceptors, but it also plays a central role in initiating and sustaining heat and mechanical hyperalgesia following inflammation. NGF signaling in pain has traditionally been thought of as primarily engaging the classic high-affinity receptor tyrosine kinase receptor TrkA to initiate sensitization events. However, the discovery that secreted proforms of nerve NGF have biological functions distinct from the processed mature factors raised the possibility that these proneurotrophins (proNTs) may have distinct function in painful conditions. ProNTs engage a novel receptor system that is distinct from that of mature neurotrophins, consisting of sortilin, a type I membrane protein belonging to the VPS10p family, and its co-receptor, the classic low-affinity neurotrophin receptor p75NTR. Here, we review how this new receptor system may itself function with or independently of the classic TrkA system in regulating inflammatory or neuropathic pain.

Impairement of HT29 Cancer Cells Cohesion by the Soluble Form of Neurotensin Receptor-3

The neurotensin (NT) receptor-3 (NTSR3), also called sortilin is a multifunctional protein localized at the intracellular and plasma membrane level. The extracellular domain of NTSR3 (sNTSR3) is released by shedding from several cell lines including colonic cancer cells. This soluble protein acts as an active ligand through its ability to bind, to be internalized in the human adenocarcinoma epithelial HT29 cells and to stimulate the PI3 kinase pathway. The aim of this study was to investigate cellular responses induced by sNTSR3 in HT29 cells. The cellular functions of sNTSR3 were monitored by immunofluocytochemistry, electron microscopy and quantitative PCR in order to characterize the cell shape and the expression of adhesion proteins. We evidenced that sNTSR3 significantly regulates the cellular morphology as well as the cell-cell and the cell-matrix adherens properties by decreasing the expession of several integrins and by modifying the structure of desmosomes. Altogether, these properties lead to an increase of cell detachment upon sNTSR3 treatment on HT29, HCT116 and SW620 cancer cells. Our results indicate that sNTSR3 may induce the first phase of a process which weaken HT29 epithelial properties including desmosome architecture, cell spreading, and initiation of cell separation, all events which could be responsible for cancer metastasis.

Neurotensin, a Novel Messenger to Cross-Link Inflammation and Tumor Invasion via Epithelial-Mesenchymal Transition Pathway

Multiple cytokines and growth factors are critical for the prognosis of cancer which has been regarded as a worldwide health problem. Recently, neuropeptides, soluble factors regulating a series of functions in the central nervous system, have also been demonstrated to stimulate the proliferation and migration of tumor cells. Among these signaling peptides, the role of neurotensin (NTS) on malignancy procession has become a hot topic. The effects of NTS on tumor growth and its antiapoptosis role have already been identified. Subsequently, studies demonstrated the impact of NTS on the migration and invasion, but the molecular mechanisms involved are still unclear at present. Recently, some reports indicated that NTS could induce expression and secretion of interleukin-8 (IL-8) to promote local imflammatory response which might participate in epithelial-mesenchymal transition (EMT)-related tumor migration. In present review, we highlight the process of tumor EMT induced by NTS through stimulating IL-8 and the significance of NTS/IL-8 pathway in clinical application prospect.