Innate immunity and neuroinflammation

CQMUH-011 Inhibits LPS-Induced Microglia Activation and Ameliorates Brain Ischemic Injury in Mice

Excessive microglial activation-mediated neuroinflammation is closely involved in the pathogenesis of several neurological diseases. CQMUH-011, as a novel adamantane sulfonamide compound, has been shown anti-inflammatory properties in activated macrophages (RAW264.7). However, the role of CQMUH-011 in microglial activation-induced neuroinflammation and neuroprotective properties has yet to be elucidated. In the present study, we investigated the potential effects and mechanisms of CQMUH-011 on lipopolysaccharide (LPS)-stimulated primary microglia in vitro and transient middle cerebral artery occlusion (t-MCAO)-induced acute cerebral ischemia/reperfusion (I/R) injury in vivo. The results demonstrated that CQMUH-011 significantly suppressed the production of tumor necrosis factor (TNF)-α and interleukin (IL)-1β by LPS-stimulated primary microglia. In addition, CQMUH-011 inhibited the proliferation of activated microglia by arresting the cell cycle at the G₁/S phase accompanied by downregulating the expression of cell cycle regulatory proteins such as proliferating cell nuclear antigen (PCNA) and cyclin D1. CQMUH-011 was seen to induce apoptosis in activated microglia by regulating the expression of Bax and Bcl-2. Furthermore, CQMUH-011 markedly attenuated the protein expression of Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) as well as the phosphorylation levels of nuclear factor-kappa (NF-κB) subunit p65, inhibitory kappa B-alpha (IκBα), and mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinase (ERK) and p38 kinases. In vivo, CQMUH-011 administration significantly improved neurological function and infarct volume, and ameliorated the inflammatory cytokines and microglia amount around the injury site of mice. In conclusion, these results suggested that CQMUH-011 has a notable anti-inflammatory effect and protects mice from I/R injure. Thus, CQMUH-011 may be a candidate drug for the treatment of cerebral ischemia patients.

Pro-inflammatory dopamine-2 receptor-specific T cells in paediatric movement and psychiatric disorders

Objectives

A dysregulated inflammatory response against the dopamine‐2 receptor (D2R) has been implicated in movement and psychiatric disorders. D2R antibodies were previously reported in a subset of these patients; however, the role of T cells in these disorders remains unknown. Our objective was to identify and characterise pro‐inflammatory D2R‐specific T cells in movement and psychiatric disorders.

Methods

Blood from paediatric patients with movement and psychiatric disorders of suspected autoimmune and neurodevelopmental aetiology (n = 24) and controls (n = 16) was cultured in vitro with a human D2R peptide library, and D2R‐specific T cells were identified by flow cytometric quantification of CD4⁺CD25⁺CD134⁺ T cells. Cytokine secretion was analysed using a cytometric bead array and ELISA. HLA genotypes were examined in D2R‐specific T‐cell‐positive patients. D2R antibody seropositivity was determined using a flow cytometry live cell‐based assay.

Results

Three immunodominant regions of D2R, amino acid (aa)121–131, aa171–181 and aa396–416, specifically activated CD4⁺ T cells in 8/24 patients. Peptides corresponding to these regions were predicted to bind with high affinity to the HLA of the eight positive patients and had also elicited the secretion of pro‐inflammatory cytokines IL‐2, IFN‐ γ, TNF, IL‐6, IL‐17A and IL‐17F. All eight patients were seronegative for D2R antibodies.

Conclusion

Autoreactive D2R‐specific T cells and a pro‐inflammatory Th1 and Th17 cytokine profile characterise a subset of paediatric patients with movement and psychiatric disorders, further underpinning the theory of immune dysregulation in these disorders. These findings offer new perspectives into the neuroinflammatory mechanisms of movement and psychiatric disorders and can influence patient diagnosis and treatment.

Neutrophils Return to Bloodstream Through the Brain Blood Vessel After Crosstalk With Microglia During LPS-Induced Neuroinflammation

The circulatory neutrophil and brain tissue-resident microglia are two important immune cells involved in neuroinflammation. Since neutrophils that infiltrate through the brain vascular vessel may affect the immune function of microglia in the brain, close investigation of the interaction between these cells is important in understanding neuroinflammatory phenomena and immunological aftermaths that follow. This study aimed to observe how morphology and function of both neutrophils and microglia are converted in the inflamed brain. To directly investigate cellular responses of neutrophils and microglia, LysM^GFP/+ and CX₃CR1^GFP/+ mice were used for the observation of neutrophils and microglia, respectively. In addition, low-dose lipopolysaccharide (LPS) was utilized to induce acute inflammation in the central nervous system (CNS) of mice. Real-time observation on mice brain undergoing neuroinflammation via two-photon intravital microscopy revealed various changes in neutrophils and microglia; namely, neutrophil infiltration and movement within the brain tissue increased, while microglia displayed morphological changes suggesting an activated state. Furthermore, neutrophils seemed to not only actively interact with microglial processes but also exhibit reverse transendothelial migration (rTEM) back to the bloodstream. Thus, it may be postulated that, through crosstalk with neutrophils, macrophages are primed to initiate a neuroinflammatory immune response; also, during pathogenic events in the brain, neutrophils that engage in rTEM may deliver proinflammatory signals to peripheral organs outside the brain. Taken together, these results both show that neuroinflammation results in significant alterations in neutrophils and microglia and lay the pavement for further studies on the molecular mechanisms behind such changes.

Cognitive Decline and Alzheimer's Disease in Old Age: A Sex-Specific Cytokinome Signature

BACKGROUND

Elevated peripheral levels of different cytokines and chemokines in subjects with Alzheimer's disease (AD), as compared with healthy controls (HC), have emphasized the role of inflammation in such a disease. Considering the cross-talking between the central nervous system and the periphery, the inflammatory analytes may provide utility as biomarkers to identify AD at earlier stages.

OBJECTIVE

Using an advanced statistical approach, we can discriminate the interactive network of cytokines/chemokines and propose a useful tool to follow the progression and evolution of AD, also in light of sex differences.

METHODS

A cohort of 289 old-age subjects was screened for cytokine and chemokine profiling, measured in plasma, after a thorough clinical and neuropsychological evaluation. A custom algorithm based on Fisher linear discriminant analysis was applied to ascertain a classification signature able to discriminate HC from mild cognitive impairment (MCI) and AD.

RESULTS

We observed that a joint expression of three proteins (a "signature" composed by IFN-α2, IL-1α, TNFα) can discriminate HC from AD with an accuracy of 65.24%. Using this signature on MCI samples, 84.93% of them were classified as "non-HC". Stratifying MCI samples by sex, we observed that 87.23% of women were classified as "non-HC", and only 57.69% of males. Indeed, in a scatter plot of IFN-α2 and IL-1α, the HC group was better separated from MCI and AD in women as compared with men.

CONCLUSION

These findings suggest that AD is accompanied by a peripheral inflammatory response that can already be present in MCI subjects, thus providing a mean for detecting this at-risk status and allow an anticipated intervention.

Neuroinflammation Mechanisms and Phytotherapeutic Intervention: A Systematic Review

Neuroinflammation is indicated in the pathogenesis of several acute and chronic neurological disorders. Acute lesions in the brain parenchyma induce intense and highly complex neuroinflammatory reactions with similar mechanisms among various disease prototypes. Microglial cells in the CNS sense tissue damage and initiate inflammatory responses. The cellular and humoral constituents of the neuroinflammatory reaction to brain injury contribute significantly to secondary brain damage and neurodegeneration. Inflammatory cascades such as proinflammatory cytokines from invading leukocytes and direct cell-mediated cytotoxicity between lymphocytes and neurons are known to cause "collateral damage" in models of acute brain injury. In addition to degeneration and neuronal cell loss, there are secondary inflammatory mechanisms that modulate neuronal activity and affect neuroinflammation which can even be detected at the behavioral level. Hence, several of health conditions result from these pathogenetic conditions which are underlined by progressive neuronal function loss due to chronic inflammation and oxidative stress. In the first part of this Review, we discuss critical neuroinflammatory mediators and their pathways in detail. In the second part, we review the phytochemicals which are considered as potential therapeutic molecules for treating neurodegenerative diseases with an inflammatory component.

Can selective serotonin reuptake inhibitors have a neuroprotective effect during COVID-19?

The absence of a specific treatment for SARS-CoV-2 infection led to an intense global effort in order to find new therapeutic interventions and improve patient outcomes. One important feature of COVID-19 pathophysiology is the activation of immune cells, with consequent massive production and release of inflammatory mediators that may cause impairment of several organ functions, including the brain. In addition to its classical role as a neurotransmitter, serotonin (5-hydroxytryptamine, 5-HT) has immunomodulatory properties, downregulating the inflammatory response by central and peripheral mechanisms. In this review, we describe the roles of 5-HT in the regulation of systemic inflammation and the potential benefits of the use of specific serotonin reuptake inhibitors as a coadjutant therapy to attenuate neurological complications of COVID-19.

Genome Wide Analysis Points towards Subtype-Specific Diseases in Different Genetic Forms of Amyotrophic Lateral Sclerosis

Amyotropic lateral sclerosis (ALS) is a lethally progressive and irreversible neurodegenerative disease marked by apparent death of motor neurons present in the spinal cord, brain stem and motor cortex. While more and more gene mutants being established for genetic ALS, the vast majority suffer from sporadic ALS (>90%). It has been challenging, thus, to model sporadic ALS which is one reason why the underlying pathophysiology remains elusive and has stalled the development of therapeutic strategies of this progressive motor neuron disease. To further unravel these pathological signaling pathways, human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs) from FUS- and SOD1 ALS patients and healthy controls were systematically compared to independent published datasets. Here through this study we created a gene profile of ALS by analyzing the DEGs, the Kyoto encyclopedia of Genes and Genomes (KEGG) pathways, the interactome and the transcription factor profiles (TF) that would identify altered molecular/functional signatures and their interactions at both transcriptional (mRNAs) and translational levels (hub proteins and TFs). Our findings suggest that FUS and SOD1 may develop from dysregulation in several unique pathways and herpes simplex virus (HSV) infection was among the topmost predominant cellular pathways connected to FUS and not to SOD1. In contrast, SOD1 is mainly characterized by alterations in the metabolic pathways and alterations in the neuroactive-ligand-receptor interactions. This suggests that different genetic ALS forms are singular diseases rather than part of a common spectrum. This is important for patient stratification clearly pointing towards the need for individualized medicine approaches in ALS.

HSPB8 overexpression prevents disruption of blood-brain barrier after intracerebral hemorrhage in rats through Akt/GSK3β/β-catenin signaling pathway

Blood brain barrier (BBB) disruption is a crucial factor contributing to secondary brain injury after intracerebral hemorrhage (ICH). Heat shock protein B8 (HSPB8) has been recently reported to confer neuroprotection against against ischaemic stroke through maintaining BBB integrity. However, the role of HSPB8 in ICH is still elusive. In this study, we found that HSPB8 was upregulated by ICH and extensively expressed in neurovascular structure including endothelial cells and astrocytes. lentivirus intracerebroventricular (i.c.v) injection achieved a widespread and persistent HSPB8 overexpression in brain tissues. HSPB8 overexpression significantly ameliorated neurobehavioral deficits and brain edema at 24 and 72h following ICH. Moreover, HSPB8 overexpression remarkedly inhibited BBB disruption and significantly increase the level of p-Akt, p-GSKβ and intranuclear β-catenin 24h post-ICH. This effect was obviously reversed by Akt specific inhibitor, MK2206. Based on these findings, HSPB8 exerted its protective effect on BBB, at least partly, via Akt/ p-GSKβ/β-catenin pathways.

Potential Roles of Myeloid Differentiation Factor 2 on Neuroinflammation and Its Possible Interventions

Neuroinflammation is the primary response by immune cells in the nervous system to protect against infection. Chronic and uncontrolled neuroinflammation triggers neuronal injury and neuronal death resulting in a variety of neurodegenerative disorders. Therefore, fine tuning of the immune response in the nervous system is now extensively considered as a potential therapeutic intervention for those diseases. The immune cells of the nervous system express Toll-like receptor 4 (TLR4) together with myeloid differentiation factor 2 (MD-2) to protect against the pathogens. Over the last 10 years, antagonists targeting the functional domains of MD-2 have become attractive pharmacological intervention strategies in pre-clinical studies into neuroinflammation and its associated brain pathologies. This review aims to summarize and discuss the roles of TLR4-MD-2 signaling pathway activation in various models of neuroinflammation. This review article also highlights the studies reporting the effect of MD-2 antagonists on neuroinflammation in in vitro and in vivo studies.

The brain consequences of systemic inflammation were not fully alleviated by ibuprofen treatment in mice

BACKGROUND

Extensive data point to the immune system as an important factor underlying the pathogenesis of brain diseases. Epidemiological studies have shown that long-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) significantly reduces the onset and progression of Alzheimer's disease. The present study aimed to investigate whether ibuprofen (IBU) is able to prevent the long-lasting alterations of brain function induced by systemic inflammation.

METHODS

Mice received intraperitoneal injections of lipopolysaccharide (LPS; 250 µg/kg/day) for seven consecutive days. Ibuprofen administration (40 mg/kg/day) was started three days before the LPS injections and continued until the last day of LPS injection. Within the next 2 weeks, mice performances on the behavioral tests were evaluated, and then brain tissue samples for biochemical analyses were collected.

RESULTS

The findings showed that ibuprofen significantly improved mice's performance in the passive avoidance test and reduced anxiety- and depressive-like behaviors. However, ibuprofen could not significantly improve spatial memory in the Morris water maze test and recognition ability in the novel object recognition test. TNF-α and IL-1β cytokines levels and malondialdehyde (MDA) concentration in the hippocampal tissues of LPS-treated mice were significantly lowered by ibuprofen treatment, whereas no significant effects on IL-10 production and hippocampal BDNF levels were observed. In addition, ibuprofen did not significantly reduce amyloid-β_1-40 levels in the hippocampus of LPS-treated animals.

CONCLUSION

Overall, the findings of the present study suggest that some, but not all, of the adverse effects of systemic inflammation are alleviated by ibuprofen treatment.

Potential Cytokine Biomarkers in Intellectual Disability

Intellectual disability (ID), previously called mental retardation, is the most common neurodevelopmental disorder characterized by life-long intellectual and adaptive functioning impairments that have an impact on individuals, families, and society. Its prevalence is estimated to 3% of the general population and its etiology is still insufficiently understood. Besides the involvement of genetic and environmental factors, immunological dysfunctions have been also suggested to contribute to the pathophysiology of ID. Over the years, immune biomarkers related to ID have gained significant attention and researchers have begun to look at possible cytokine profiles in individuals suffered from this disorder. In fact, in addition to playing crucial physiological roles in the majority of normal neurodevelopmental processes, cytokines exert an important role in neuroinflammation under pathological conditions, and interactions between the immune system and central nervous system have long been under investigation. Cytokine levels imbalance has been reported associated with some behavioral characteristics and the onset of some syndromic forms of ID. In this review, we will focus on immunological biomarkers, especially the cytokine profiles that have been identified in people with ID. Thus, data reported and discussed in the present paper may provide additional information to start further studies and to plan strategies for early identification and managing of ID.

Mediterranean Diet: Lipids, Inflammation, and Malaria Infection

The Mediterranean diet (MedDiet) consists of consumption of vegetables and healthy oils and have beneficial effects on metabolic and inflammatory diseases. Our goal here is to discuss the role of fatty acid content in MedDiet, mostly omega-3, omega-6, and omega-9 on malaria. Malaria affects millions of people around the globe. The parasite Plasmodium causes the disease. The metabolic and inflammatory alterations in the severe forms have damaging consequences to the host. The lipid content in the MedDiet holds anti-inflammatory and pro-resolutive features in the host and have detrimental effects on the Plasmodium. The lipids from the diet impact the balance of pro- and anti-inflammation, thus, lipids intake from the diet is critical to parasite elimination and host tissue damage caused by an immune response. Herein, we go into the cellular and molecular mechanisms and targets of the MedDiet fatty acids in the host and the parasite, reviewing potential benefits of the MedDiet, on inflammation, malaria infection progression, and clinical outcome.

Exosomes: Potential Therapies for Disease via Regulating TLRs

Exosomes are small membrane vesicles that retain various substances such as proteins, nucleic acids, and small RNAs. Exosomes play crucial roles in many physiological and pathological processes, including innate immunity. Innate immunity is an important process that protects the organism through activating pattern recognition receptors (PRRs), which then can induce inflammatory factors to resist pathogen invasion. Toll-like receptor (TLR) is one member of PRRs and is important in pathogen clearance and nervous disease development. Although exosomes and TLRs are two independent materials, abundant evidences imply exosomes can regulate innate immunity through integrating with TLRs. Herein, we review the most recent data regarding exosome regulation of TLR pathways. Specifically, exosome-containing materials can regulate TLR pathways through the interaction with TLRs. This is a new strategy regulating immunity to resist pathogens and therapy diseases, which provide a potential method to cure diseases.

Mesenchymal Stem Cells Could Be Considered as a Candidate for Further Studies in Cell-Based Therapy of Alzheimer's Disease via Targeting the Signaling Pathways

Mesenchymal stem cells (MSCs) are of particular interest because of their potential in regenerative medicine. Stem cell-based therapies cast a new hope for neurodegenerative disease treatment as a regeneration strategy, including treatment for Alzheimer's disease (AD). A multitude of cytokines and factors secreted from MSCs are known to give such multifunctional properties, but associated mechanisms of these factors have yet to be entirely understood. To better understand the in vitro effect of MSCs on a neurodegenerative disorder, we treated primary cortical and hippocampal neural cells with amyloid β (Aβ) as an in vitro cell line model for AD. For this purpose, bone marrow-derived MSCs (BMSCs) were cocultured with Aβ-treated neural cells, collected at day 3, and subjected to absolute telomere length measurement and telomerase activity assay. Next, the gene and protein expression levels of mTOR, p-mTOR, AMPK, p-AMPK, GSK-3β, p-GSK-3β, Wnt3, and β-catenin were investigated. Also, after 3 days of coculture treatment, the supernatant was collected from both groups for cytokine measurement. It was found that telomere length as a biomarker in neurodegenerative disorder as well as telomerase activity had significantly increased in the experimental group, and the presence of IL-6, IL-10, and TGF-β was obviously significant in the cocultured media. Also, BMSCs significantly changed the gene and protein expression of mTOR, AMPK, GSK-3β, and Wnt3/β-catenin signaling pathways components. It was concluded that the mentioned effects of MSCs on neural cells as an in vitro cell line model for AD as a therapeutic agent can be related to the signaling network.

Dual roles of astrocytes in plasticity and reconstruction after traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of fatality and disability worldwide. Despite its high prevalence, effective treatment strategies for TBI are limited. Traumatic brain injury induces structural and functional alterations of astrocytes, the most abundant cell type in the brain. As a way of coping with the trauma, astrocytes respond in diverse mechanisms that result in reactive astrogliosis. Astrocytes are involved in the physiopathologic mechanisms of TBI in an extensive and sophisticated manner. Notably, astrocytes have dual roles in TBI, and some astrocyte-derived factors have double and opposite properties. Thus, the suppression or promotion of reactive astrogliosis does not have a substantial curative effect. In contrast, selective stimulation of the beneficial astrocyte-derived molecules and simultaneous attenuation of the deleterious factors based on the spatiotemporal-environment can provide a promising astrocyte-targeting therapeutic strategy. In the current review, we describe for the first time the specific dual roles of astrocytes in neuronal plasticity and reconstruction, including neurogenesis, synaptogenesis, angiogenesis, repair of the blood-brain barrier, and glial scar formation after TBI. We have also classified astrocyte-derived factors depending on their neuroprotective and neurotoxic roles to design more appropriate targeted therapies.

BabaoDan cures hepatic encephalopathy by decreasing ammonia levels and alleviating inflammation in rats

ETHNOPHARMACOLOGICAL RELEVANCE

BabaoDan (BBD) is a famous traditional Chinese formula frequently used in TCM clinics to eliminate jaundice and treat infectious viral hepatitis. This paper assesses BBD's preventive and therapeutic effects on hepatic encephalopathy after liver cirrhosis (CHE) and acute liver failure (AHE) in rats and explains its possible mechanism of action.

METHODS

CHE rat model was established by injection of carbon tetrachloride (CCl4) twice a week for a total of 9 weeks and then by injection of thioacetamide (TAA) to induce hepatic encephalopathy. AHE rat model was established by injection of TAA once a day for a total of 3 days. In CHE rat model, BBD was gavaged once a day at the end of the 6th week until the experiment ended. In AHE rat model,BBD was gavaged once a day 3 days before TAA injection until the experiment ended. The preventive and therapeutic effects of BBD on brain dysfunction, as well as liver injury, pathology and fibrosis were evaluated in vivo. The role of BBD in the regulation of inflammatory factors and myeloid differentiation factor 88/Toll-like receptor 4/nuclear factor kappa-B (TLR4/MyD88/NK-κ B) pathway was detected in both liver and brain in vivo. The rat bone marrow derived macrophages (BMDMs) were activated by Lipopolysaccharide (LPS), and the role of BBD in the regulation of inflammatory factors and NK-κ B pathway were detected in vitro.

RESULTS

In CHE rat model: BBD significantly improved the total distance as well as the activity rate of rats. BBD also improved the learning and memory abilities of rats compared with the control group. In addition, BBD effectively decreased ammonia levels and significantly decreased the levels of alanine aminotransferase (ALT), aspartate transaminase (AST), total bilirubin (TBil) and total bile acid (TBA), as well as improved the levels of total protein (TP) and albumin (Alb). In the liver, BBD not only inhibited the gene expressions of tumor necrosis factor alpha (TNF-α), interleukini-6 (IL-6), TLR4, MyD88, and NF-κ B but also inhibited the protein expressions of TLR4, MyD88, NK-κ B and TNF-α. In the brain, BBD inhibited the gene expressions of iNOS, IL-6, TNF-α, TLR-4, MyD88, and NF-κ B, as well as inhibited the protein expressions of TLR4, MyD88, P65 TNF-α and ionized calcium binding adapter molecule 1 (Iba-1). BBD also decreased NO and TNF-α in the blood.

IN AHE RAT MODEL

BBD improved neurological scores, blood ammonia levels and the brain inflammatory gene expressions of iNOS, TNF-α and IL-1β. BBD also improved liver function biomarkers such as ALT, TBil, TBA, TP, ALB and inflammatory and apoptotic gene expressions of TNF-α, IL-1β, IL-6, Bax, Bcl-2, caspase-9, caspase-3 and NF-κ B. In LPS-activated rat BMDMs, BBD decreased NO and TNF-α production in BMDM culture supernatant. In addition, BBD inhibited the gene expressions of TNF-α, IL-1 β and IL-6 as well as the phosphorylation of P65.

CONCLUSION

BBD can prevent and cure hepatic encephalopathy (HE) derived from both chronic and acute liver diseases. BBD can reduce hyperammonemia as well as the systematic and neurological inflammation. Inflammation is likely an important target of BBD to treat HE. The anti-inflammatory role of BBD may lie in its regulation of the TLR4/MyD88/NF-κ B pathways.

Paroxetine suppresses reactive microglia-mediated but not lipopolysaccharide-induced inflammatory responses in primary astrocytes

BACKGROUND

Astrocytes are the most abundant glial cells in a brain that mediate inflammatory responses and provide trophic support for neurons. We have previously disclosed that paroxetine, a common selective serotonin reuptake inhibitor, ameliorates LPS-induced microglia activation. However, it remains elusive for the role of paroxetine in astrocytic responses.

METHODS

Isolated primary astrocytes were pretreated with paroxetine and stimulated with different stimuli, lipopolysaccharide (LPS) or microglia conditioned medium pre-activated with LPS (M/Lps). Inflammatory and neurotrophic responses, underlying mechanisms and the impact on neuronal survival were assessed.

RESULTS

Paroxetine had no impact on LPS-stimulated iNOS, TNF-α, and IL-1β expression, but inhibited M/Lps-induced TNF-α and IL-1β expression in primary astrocytes. Paroxetine suppressed M/Lps- but not LPS-induced activation of NF-κB and had no impact on the activation of MAPKs and STAT3. Incubation with the resulted astrocyte conditioned media caused no change in the viability of SH-SY5Y cells. BDNF and MANF mRNA expressions were upregulated by M/Lps and paroxetine, respectively. However, M/Lps- or LPS-induced extracellular releases of NO, TNF-α, and/or BDNF in astrocytes were in minor amount compared to those by microglia.

CONCLUSIONS

Paroxetine ameliorates the reactive microglia-mediated inflammatory responses in astrocytes partially via inhibition of the NF-κB pathway but has no impact on LPS-stimulated astrocyte activation. While the effects of paroxetine on secondary astrocytic responses are not robust compared to its effect on the innate immune responses of microglia, the results together may implicate a therapeutic potential of paroxetine against neuroinflammation-associated neurological disorders such as Parkinson's disease.

Neuroinflammation as a Common Feature of Neurodegenerative Disorders

Neurodegenerative diseases share the fact that they derive from altered proteins that undergo an unfolding process followed by formation of β-structures and a pathological tendency to self-aggregate in neuronal cells. This is a characteristic of tau protein in Alzheimer’s disease and several tauopathies associated with tau unfolding, α-synuclein in Parkinson’s disease, and huntingtin in Huntington disease. Usually, the self-aggregation products are toxic to these cells, and toxicity spreads all over different brain areas. We have postulated that these protein unfolding events are the molecular alterations that trigger several neurodegenerative disorders. Most interestingly, these events occur as a result of neuroinflammatory cascades involving alterations in the cross-talks between glial cells and neurons as a consequence of the activation of microglia and astrocytes. The model we have hypothesized for Alzheimer’s disease involves damage signals that promote glial activation, followed by nuclear factor NF-kβ activation, synthesis, and release of proinflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6, and IL-12 that affect neuronal receptors with an overactivation of protein kinases. These patterns of pathological events can be applied to several neurodegenerative disorders. In this context, the involvement of innate immunity seems to be a major paradigm in the pathogenesis of these diseases. This is an important element for the search for potential therapeutic approaches for all these brain disorders.

The involvement of microglia in Alzheimer's disease: a new dog in the fight

First described clinically in 1906, Alzheimer's disease (AD) is the most common neurodegenerative disease and form of dementia worldwide. Despite its prevalence, only five therapies are currently approved for AD, all dealing with the symptoms rather than the underlying causes of the disease. A multitude of experimental evidence has suggested that the once thought inconsequential process of neuroinflammation does, in fact, contribute to the AD pathogenesis. One such CNS cell type critical to this process are microglia. Plastic in nature with varied roles, microglia are emerging as key contributors to AD pathology. This review will focus on the role of microglia in the neuroinflammatory response in AD, highlighting recent studies implicating aberrant changes in microglial function in disease progression. Of critical note is that with these advances, a reconceptualization of the framework in which we view microglia is required. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc.

Role of AIM2 inflammasome in inflammatory diseases, cancer and infection

AIM2 is a cytosolic innate immune receptor which recognizes double-stranded DNA (dsDNA) released during cellular perturbation and pathogenic assault. AIM2 recognition of dsDNA leads to the assembly of a large multiprotein oligomeric complex termed the inflammasome. This inflammasome assembly leads to the secretion of bioactive interleukin-1β (IL-1β) and IL-18 and induction of an inflammatory form of cell death called pyroptosis. Sensing of dsDNA by AIM2 in the cytosol is crucial to mediate protection against the invading pathogens including bacteria, virus, fungi and parasites. AIM2 also responds to dsDNA released from damaged host cells, resulting in the secretion of the effector cytokines thereby driving the progression of sterile inflammatory diseases such as skin disease, neuronal disease, chronic kidney disease, cardiovascular disease and diabetes. Additionally, the protection mediated by AIM2 in the development of colorectal cancer depends on its ability to regulate epithelial cell proliferation and gut microbiota in maintaining intestinal homeostasis independently of the effector cytokines. In this review, we will highlight the recent progress on the role of the AIM2 inflammasome as a guardian of cellular integrity in modulating chronic inflammatory diseases, cancer and infection.

Liver X Receptor Alpha Is Important in Maintaining Blood-Brain Barrier Function

Dysfunction of the blood-brain barrier (BBB) contributes significantly to the pathogenesis of several neuroinflammatory diseases, including multiple sclerosis (MS). Potential players that regulate BBB function are the liver X receptors (LXRs), which are ligand activated transcription factors comprising two isoforms, LXRα, and LXRβ. However, the role of LXRα and LXRβ in regulating BBB (dys)function during neuroinflammation remains unclear, as well as their individual involvement. Therefore, the goal of the present study is to unravel whether LXR isoforms have different roles in regulating BBB function under neuroinflammatory conditions. We demonstrate that LXRα, and not LXRβ, is essential to maintain barrier integrity in vitro. Specific knockout of LXRα in brain endothelial cells resulted in a more permeable barrier with reduced expression of tight junctions. Additionally, the observed dysfunction was accompanied by increased endothelial inflammation, as detected by enhanced expression of vascular cell adhesion molecule (VCAM-1) and increased transendothelial migration of monocytes toward inflammatory stimuli. To unravel the importance of LXRα in BBB function in vivo, we made use of the experimental autoimmune encephalomyelitis (EAE) MS mouse model. Induction of EAE in a constitutive LXRα knockout mouse and in an endothelial specific LXRα knockout mouse resulted in a more severe disease score in these animals. This was accompanied by higher numbers of infiltrating leukocytes, increased endothelial VCAM-1 expression, and decreased expression of the tight junction molecule claudin-5. Together, this study reveals that LXRα is indispensable for maintaining BBB integrity and its immune quiescence. Targeting the LXRα isoform may help in the development of novel therapeutic strategies to prevent BBB dysfunction, and thereby neuroinflammatory disorders.

Sp1 in Astrocyte Is Important for Neurite Outgrowth and Synaptogenesis

In this study, we found that Sp1 was highly expressed in astrocytes, implying that Sp1 might be important for the function of astrocytes. Sp1/GFAP-Cre-ERT2 conditional knockout mice were constructed to study the role of Sp1 in astrocytes. Knockout of Sp1 in astrocytes altered astrocytic morphology and decreased GFAP expression in the cortex and hippocampus but did not affect cell viability. Loss of Sp1 in astrocytes decreased the number of neurons in the cortex and hippocampus. Conditioned medium from primary astrocytes with Sp1 knockout disrupted neuronal dendritic outgrowth and synapse formation, resulting in abnormal learning, memory, and motor behavior. Sp1 knockout in astrocytes altered gene expression, including decreasing the expression of Toll-like receptor 2 and Cfb and increasing the expression of C1q and C4Bp, thereby affecting neurite outgrowth and synapse formation, resulting in disordered neuron function. Studying these gene regulations might be beneficial to understanding neuronal development and brain injury prevention.

Oxymatrine can attenuate pathological deficits of Alzheimer's disease mice through regulation of neuroinflammation

Alzheimer's disease (AD) is a common neurodegenerative disorder characterized by progressive learning and cognitive damage. Several hypotheses such as amyloid cascade hypothesis, hyper-phosphorylated τ hypothesis, and energy metabolism hypothesis have been proposed to elucidate the disease. However, the exact mechanism of AD remains unclear and current therapeutic strategies are miserable. Cumulative evidence showed that neuroinflammation plays a significant role in the pathogenesis of the AD. Oxymatrine (OMT), a plant-derived bioactive compound, has anti-viral, anti-fibrosis, and anti-tumor effects through the involvement of several immune-related signaling pathways. Whether OMT can attenuate the pathology of AD is largely unknown. In this manuscript, we found that treatment of OMT can significantly improve cognitive and learning abilities of AD mice during various behavioral test. Treatment of OMT can significantly reduce the densities of Aβ plaques and astrocyte clusters in the neocortex and hippocampus of AD mice. Furthermore, treatment of OMT significantly reduced the concentration of pro-inflammatory cytokines including IL-6, IL-1β, TNF-α and IL-17A in AD mice. Taken together, our data indicate that OMT may serve as a potential drug for AD.

Imiquimod and interferon-alpha augment monocyte-mediated astrocyte secretion of MCP-1, IL-6 and IP-10 in a human co-culture system

Toll-like receptor 7 (TLR7)-activation has been implicated as a significant mechanism of neuroinflammation triggered by ssRNA viruses. Infiltration of monocytes into the brain and astrocyte activation occurs during in vivo TLR7-mediated neuroinflammation. The objective here was to determine whether the TLR7 agonist, imiquimod, and interferon-alpha (IFN-α), promote monocyte-mediated astrocyte secretion of pro-inflammatory factors. Using a human primary co-culture system, we demonstrate that monocytes, together with imiquimod and IFN-α, promote astrocyte secretion of MCP-1, IL-6 and IP-10. Furthermore, TLR7-induced monocyte-derived IL-1β is critical for promoting the astrocyte response. Overall, this study provides a potential mechanism for TLR7-mediated neuroinflammation.

Low Evolutionary Selection Pressure in Senescence Does Not Explain the Persistence of Aβ in the Vertebrate Genome

The argument is frequently made that the amyloid-β protein (Aβ) persists in the human genome because Alzheimer's disease (AD) primarily afflicts individuals over reproductive age and, therefore, there is low selective pressure for the peptide's elimination or modification. This argument is an important premise for AD amyloidosis models and therapeutic strategies that characterize Aβ as a functionless and intrinsically pathological protein. Here, we review if evolutionary theory and data on the genetics and biology of Aβ are consistent with low selective pressure for the peptide's expression in senescence. Aβ is an ancient neuropeptide expressed across vertebrates. Consistent with unusually high evolutionary selection constraint, the human Aβ sequence is shared by a majority of vertebrate species and has been conserved across at least 400 million years. Unlike humans, the overwhelming majority of vertebrate species do not cease reproduction in senescence and selection pressure is maintained into old age. Hence, low selective pressure in senescence does not explain the persistence of Aβ across the vertebrate genome. The "Grandmother hypothesis" (GMH) is the prevailing model explaining the unusual extended postfertile period of humans. In the GMH, high risk associated with birthing in old age has lead to early cessation of reproduction and a shift to intergenerational care of descendants. The rechanneling of resources to grandchildren by postreproductive individuals increases reproductive success of descendants. In the GMH model, selection pressure does not end following menopause. Thus, evolutionary models and phylogenetic data are not consistent with the absence of reproductive selection pressure for Aβ among aged vertebrates, including humans. Our analysis suggests an alternative evolutionary model for the persistence of Aβ in the vertebrate genome. Aβ has recently been identified as an antimicrobial effector molecule of innate immunity. High conservation across the Chordata phylum is consistent with strong positive selection pressure driving human Aβ's remarkable evolutionary longevity. Ancient origins and widespread conservation suggest the human Aβ sequence is highly optimized for its immune role. We detail our analysis and discuss how the emerging "Antimicrobial Protection Hypothesis" of AD may provide insights into possible evolutionary roles for Aβ in infection, aging, and disease etiology.

Intrathecal complement activation by the classical pathway in tick-borne encephalitis

Tick-borne encephalitis (TBE) is one of the most prevalent viral central nervous system (CNS) infections in Eurasia and neurological sequelae are common. The immune responses are considered crucial for the pathogenesis. The aim of this study was to explore the activation of the complement system in TBE. The complement system is a part of the innate immune response in the CNS, which previously has been reported to be activated in other flavivirus infections. We analyzed complement factors in 44 paired cerebrospinal fluid (CSF) and serum samples from 20 cases of TBE in the acute and later stages, as well as in serum and CSF from 32 healthy controls. The concentrations of complement factors C1q, C3a, C3b, and C5a were determined with commercially available ELISA kits. Clinical data to categorize the severity of disease and outcome was retrieved from the medical records of the TBE patients. We found significantly higher concentrations of all of the analyzed complement factors in the CSF from TBE patients compared to the healthy controls. In particular, the marked increment of C1q concentrations in the CSF (p < 0,001 as compared to controls) indicated an intrathecal activation by the classical pathway. There was no correlation between complement factor concentrations in the CSF and severity of the disease in the acute phase or with sequelae at 6 months follow-up. We have found an intrathecal complement activation in TBE, and the marked increase of complement factor C1q indicated an activation by the classical pathway.

HADC8 Inhibitor WK2-16 Therapeutically Targets Lipopolysaccharide-Induced Mouse Model of Neuroinflammation and Microglial Activation

Glial activation and neuroinflammatory processes play important roles in the pathogenesis of brain abscess and neurodegenerative diseases. Activated glial cells can secrete various proinflammatory cytokines and neurotoxic mediators, which contribute to the exacerbation of neuronal cell death. The inhibition of glial activation has been shown to alleviate neurodegenerative conditions. The present study was to investigate the specific HDAC8 inhibitor WK2-16, especially its effects on the neuroinflammatory responses through glial inactivation. WK2-16 significantly reduced the gelatinolytic activity of MMP-9, and expression of COX-2/iNOS proteins in striatal lipopolysaccharide (LPS)-induced neuroinflammation in C57BL/6 mice. The treatment of WK2-16 markedly improved neurobehavioral deficits. Immunofluorescent staining revealed that WK2-16 reduced LPS-stimulated astrogliosis and microglial activation in situ. Consistently, cellular studies revealed that WK2-16 significantly suppressed LPS-induced mouse microglia BV-2 cell proliferation. WK2-16 was proven to concentration-dependently induce the levels of acetylated SMC3 in microglial BV-2 cells. It also reduced the expression of COX-2/iNOS proteins and TNF-α production in LPS-activated microglial BV-2 cells. The signaling studies demonstrated that WK2-16 markedly inhibited LPS-activated STAT-1/-3 and Akt activation, but not NF-κB or MAPK signaling. In summary, the HDAC8 inhibitor WK2-16 exhibited neuroprotective effects through its anti-neuroinflammation and glial inactivation properties, especially in microglia in vitro and in vivo.

Neuroinflammation in preterm babies and autism spectrum disorders

Genetic anomalies have a role in autism spectrum disorders (ASD). Each genetic factor is responsible for a small fraction of cases. Environment factors, like preterm delivery, have an important role in ASD. Preterm infants have a 10-fold higher risk of developing ASD. Preterm birth is often associated with maternal/fetal inflammation, leading to a fetal/neonatal inflammatory syndrome. There are demonstrated experimental links between fetal inflammation and the later development of behavioral symptoms consistent with ASD. Preterm infants have deficits in connectivity. Most ASD genes encode synaptic proteins, suggesting that ASD are connectivity pathologies. Microglia are essential for normal synaptogenesis. Microglia are diverted from homeostatic functions towards inflammatory phenotypes during perinatal inflammation, impairing synaptogenesis. Preterm infants with ASD have a different phenotype from term born peers. Our original hypothesis is that exposure to inflammation in preterm infants, combined with at risk genetic background, deregulates brain development leading to ASD.

Toll-like receptor 2 confers partial neuroprotection during prion disease

Neuroinflammation and neurodegeneration are common during prion infection, but the mechanisms that underlie these pathological features are not well understood. Several components of innate immunity, such as Toll-like receptor (TLR) 4 and Complement C1q, have been shown to influence prion disease. To identify additional components of innate immunity that might impact prion disease within the central nervous system (CNS), we screened RNA from brains of pre-clinical and clinical 22L-infected mice for alterations in genes associated with innate immunity. Transcription of several genes encoding damage-associated molecular pattern (DAMP) proteins and receptors were increased in the brains of prion-infected mice. To investigate the role of some of these proteins in prion disease of the CNS, we infected mice deficient in DAMP receptor genes Tlr2, C3ar1, and C5ar1 with 22L scrapie. Elimination of TLR2 accelerated disease by a median of 10 days, while lack of C3aR1 or C5aR1 had no effect on disease tempo. Histopathologically, all knockout mouse strains tested were similar to infected control mice in gliosis, vacuolation, and PrPSc deposition. Analysis of proinflammatory markers in the brains of infected knockout mice indicated only a few alterations in gene expression suggesting that C5aR1 and TLR2 signaling did not act synergistically in the brains of prion-infected mice. These results indicate that signaling through TLR2 confers partial neuroprotection during prion infection.

Pivotal role of carnosine in the modulation of brain cells activity: Multimodal mechanism of action and therapeutic potential in neurodegenerative disorders

Carnosine (β-alanyl-l-histidine), a dipeptide, is an endogenous antioxidant widely distributed in excitable tissues like muscles and the brain. Although discovered more than a hundred years ago and having been extensively studied in the periphery, the role of carnosine in the brain remains mysterious. Carnosinemia, a rare metabolic disorder with increased levels of carnosine in urine and low levels or absence of carnosinase in the blood, is associated with severe neurological symptoms in humans. This review deals with the role of carnosine in the brain in both physiological and pathological conditions, with a focus on preclinical evidence suggesting a high therapeutic potential of carnosine in neurodegenerative disorders. We review carnosine and carnosinemia's discoveries and the extensive research on the role and benefits of carnosine in the periphery. We then turn to carnosine's biochemistry and distribution in the brain. Using an array of recent observations as a foundation, we draw a parallel with the role of carnosine in muscles and speculate on the role of carnosine in promoting the metabolic support of neurons by glial cells. Finally, carnosine has been shown to exert a multimodal activity including inhibition of protein cross-linking and aggregation of amyloid-β and related proteins, free radical generation, nitric oxide detoxification, and an anti-inflammatory activity. It could thus play an important role in the prevention and treatment of neurodegenerative diseases such as Alzheimer's disease. We discuss the potential of carnosine in this context and speculate on new preclinical research directions.

Chlamydia pneumoniae: An Etiologic Agent for Late-Onset Dementia

The disease known as late-onset Alzheimer's disease is a neurodegenerative condition recognized as the single most commonform of senile dementia. The condition is sporadic and has been attributed to neuronal damage and loss, both of which have been linked to the accumulation of protein deposits in the brain. Significant progress has been made over the past two decades regarding our overall understanding of the apparently pathogenic entities that arise in the affected brain, both for early-onset disease, which constitutes approximately 5% of all cases, as well as late-onset disease, which constitutes the remainder of cases. Observable neuropathology includes: neurofibrillary tangles, neuropil threads, neuritic senile plaques and often deposits of amyloid around the cerebrovasculature. Although many studies have provided a relatively detailed knowledge of these putatively pathogenic entities, understanding of the events that initiate and support the biological processes generating them and the subsequent observable neuropathology and neurodegeneration remain limited. This is especially true in the case of late-onset disease. Although early-onset Alzheimer's disease has been shown conclusively to have genetic roots, the detailed etiologic initiation of late-onset disease without such genetic origins has remained elusive. Over the last 15 years, current and ongoing work has implicated infection in the etiology and pathogenesis of late-onset dementia. Infectious agents reported to be associated with disease initiation are various, including several viruses and pathogenic bacterial species. We have reported extensively regarding an association between late-onset disease and infection with the intracellular bacterial pathogen Chlamydia pneumoniae. In this article, we review previously published data and recent results that support involvement of this unusual respiratory pathogen in disease induction and development. We further suggest several areas for future research that should elucidate details relating to those processes, and we argue for a change in the designation of the disease based on increased understanding of its clinical attributes.

Formyl-Peptide Receptors in Infection, Inflammation, and Cancer

Formyl-peptide receptors (FPRs) recognize bacterial and mitochondrial formylated peptides as well as endogenous non-formylated peptides and even lipids. FPRs are expressed on various host cell types but most strongly on neutrophils and macrophages. After the discovery of FPRs on leukocytes, it was assumed that these receptors predominantly govern a proinflammatory response resulting in chemotaxis, degranulation, and oxidative burst during infection. However, it is clear that the activation of FPRs has more complex consequences and can also promote the resolution of inflammation. Recent studies have highlighted associations between FPR function and inflammatory conditions, including inflammatory disorders, cancer, and infection. In this review we discuss these recent findings.

Transcriptomic Landscapes of Immune Response and Axonal Regeneration by Integrative Analysis of Molecular Pathways and Interactive Networks Post-sciatic Nerve Transection

Potential interaction between immune response and axonal regeneration has recently attracted much attention in peripheral nervous system (PNS). Previously, global mRNA expression changes in proximal nerve segments were profiled and merely focused on the differentially change of the key biological processes. To further uncover molecular mechanisms of peripheral nerve regeneration, here we focused on the interaction between immune response and axonal regeneration that associated with specific molecular pathways and interactive networks following sciatic nerve transection. To offer an outline of the specific molecular pathways elaborating axonal regeneration and immune response, and to figure out the molecular interaction between immune response and axonal regeneration post-sciatic nerve transection, we carried out comprehensive approaches, including gene expression profiling plus multi-level bioinformatics analysis and then further experimental validation. Alcam, Nrp1, Nrp2, Rac1, Creb1, and Runx3 were firstly considered as the key or hub genes of the protein-protein interaction (PPI) network in rat models of sciatic nerve transection, which are highly correlated with immune response and axonal regeneration. Our work provide a new way to figure out molecular mechanism of peripheral nerve regeneration and valuable resources to figure out the molecular courses which outline neural injury-induced micro-environmental variation to discover novel therapeutic targets for axonal regeneration.

Markers of Environmental Enteric Dysfunction Are Associated With Neurodevelopmental Outcomes in Tanzanian Children

BACKGROUND

Chronic exposure to enteropathogens may result in environmental enteric dysfunction (EED), a subclinical condition associated with poor child growth. Growth faltering is strongly associated with poor neurodevelopment, and occurs during sensitive periods of postnatal brain development. We investigated the role of novel EED biomarkers, systemic inflammation, and micronutrient status on neurodevelopment in Tanzanian children.

METHODS

Non-stunted subjects with 6-week and 6-month blood samples and neurodevelopmental measures (n = 107) were included in this study. Samples were tested for biomarkers of gastrointestinal function (citrulline, antibodies to lipopolysaccharide, and flagellin), micronutrient status (iron, retinol binding protein [RBP], and vitamin D), systemic inflammation (C-reactive protein [CRP] and alpha-1-acid glycoprotein), and growth (insulin-like growth factor and insulin-like growth factor binding protein 3).

RESULTS

Cognitive scores at 15 months were associated with higher concentrations of 6-month anti-lipopolysaccharide IgG (β = 1.95, P = 0.02), anti-flagellin IgA (β = 2.41, P = 0.04), and IgG (β = 2.99, P = 0.009). Higher receptive language scores were positively associated with anti-flagellin IgG (β = 0.95, P = 0.05), and receptive language and gross motor scores were positively associated with citrulline at 6 months (β = 0.09, P = 0.02; β = 0.10, P = 0.03, respectively). Gross motor scores were positively associated with RBP at 6 months (β = 1.70, P = 0.03). Markers of systemic inflammation were not significantly associated with neurodevelopment.

CONCLUSIONS

Plasma citrulline, a marker of gastrointestinal mucosal surface area, and vitamin A status were associated with higher gross motor development scores. Novel markers for EED, but not inflammation, were positively associated with cognitive scores, suggesting a possible mechanistic pathway involving immune response and neuroprotection.

[Dynamics of clinical and biological indices of the asthenic symptom-complex during immunotropic therapy of patients with schizophrenia]

AIM

To identify clinical, psychopathological, and immunological features of the asthenic symptom-complex in patients with schizophrenia and to analyze the possibility of optimizing complex therapy of these conditions using the immunotropic drug bestim.

MATERIAL AND METHODS

Forty-three male patients, aged 20-55 years, were examined. Clinical examination of patients (PANSS, MFI-20) was performed before, and 5, 30 days after the end of treatment. The activity of inflammatory markers (leukocyte elastase (LE) and a1-proteinase inhibitor (a1-PI)) was determined in blood serum.

RESULTS

The affective-asthenic (32.5%) and asthenic-negative (67.5%) variants of the asthenic symptom-complex in schizophrenia characterized by different immune reactions (depending on LE activity) were revealed. Complex therapy with bestim contributed to a statistically significant reduction in the main clinical manifestations of endogenous asthenia in the majority of patients. More significant regression at a remote stage of the study was observed in the astheno-negative group of patients (p<0.001).

CONCLUSION

LE and a1-PI reflect the clinical and biological features of the asthenic symptom-complex which develops within the endogenous process. Normal/reduced activity of LE accompanied by the increased activity of a1-PI is the best predictor of bestim efficacy in terms of reduction of asthenic symptoms.

Involvement of Innate Immune System in Late Stages of Inherited Photoreceptor Degeneration

Retinitis pigmentosa (RP) is a group of inherited retinal degenerations that lead to progressive vision loss. Many mutations in 60 different genes have been shown to cause RP. Given the diversity of genes and mutations that cause RP, corrective gene therapy approaches currently in development may prove both time-consuming and cost-prohibitive for treatment of all forms of RP. An alternative approach is to find common biological pathways that cause retinal degeneration in various forms of RP, and identify new molecular targets. With this goal, we analyzed the retinal transcriptome of two non-allelic forms of RP in dogs, rcd1 and xlpra2, at clinically relevant advanced stages of the two diseases. Both diseases showed very similar trends in changes in gene expression compared to control normal dogs. Pathway analysis revealed upregulation of various components of the innate immune system in both diseases, including inflammasome and complement pathways. Our results show that the retinal transcriptome at advanced stages of RP is very similar to that of other retinal degenerative diseases such as age-related macular degeneration and diabetic retinopathy. Thus, drugs and therapeutics already in development for targeting these retinopathies may also prove useful for the treatment of many forms of RP.

Schizophrenia-risk and urban birth are associated with proteomic changes in neonatal dried blood spots

In the present study, we tested whether there were proteomic differences in blood between schizophrenia patients after the initial onset of the disorder and controls; and whether those differences were also present at birth among neonates who later developed schizophrenia compared to those without a psychiatric admission. We used multiple reaction monitoring mass spectrometry to quantify 77 proteins (147 peptides) in serum samples from 60 first-onset drug-naive schizophrenia patients and 77 controls, and 96 proteins (152 peptides) in 892 newborn blood-spot (NBS) samples collected between 1975 and 1985. Both serum and NBS studies showed significant alterations in protein levels. Serum results revealed that Haptoglobin and Plasma protease C1 inhibitor were significantly upregulated in first-onset schizophrenia patients (corrected P < 0.05). Alpha-2-antiplasmin, Complement C4-A and Antithrombin-III were increased in first-onset schizophrenia patients (uncorrected P-values 0.041, 0.036 and 0.013, respectively) and also increased in newborn babies who later develop schizophrenia (P-values 0.0058, 0.013 and 0.044, respectively). We also tested whether protein abundance at birth was associated with exposure to an urban environment during pregnancy and found highly significant proteomic differences at birth between urban and rural environments. The prediction model for urbanicity had excellent predictive performance in both discovery (area under the receiver operating characteristic curve (AUC) = 0.90) and validation (AUC = 0.89) sample sets. We hope that future biomarker studies based on stored NBS samples will identify prognostic disease indicators and targets for preventive measures for neurodevelopmental conditions, particularly those with onset during early childhood, such as autism spectrum disorder.

Untangling the most probable role for vitamin D3 in autism

Recent studies indicate an important role for vitamin D3 in autism spectrum disorder (ASD), although its mechanism is not completely understood. The most puzzling aspect of ASD is that identical twins, who share identical DNA, do not have 100% concordance rates (∼88% for identical and ∼31% for fraternal twins). These findings provide major clues into the etiology: ASD must involve an environmental factor present in the prenatal milieu that both identical twins are not always exposed to because they do not always share it (i.e., placentas). Combined with the exponential increasing rates of ASD around the world, these observations suggest a contagious disease is probably transferred to the fetus via the placenta becoming infected by a cervical virus. Vitamin D3 boosts immune responses clearing viral infections and increases serotonin and estrogen brain levels. Here we review the different roles and untangle the most probable one vitamin D3 plays in ASD.

The putative role of environmental aluminium in the development of chronic neuropathology in adults and children. How strong is the evidence and what could be the mechanisms involved?

The conceptualisation of autistic spectrum disorder and Alzheimer's disease has undergone something of a paradigm shift in recent years and rather than being viewed as single illnesses with a unitary pathogenesis and pathophysiology they are increasingly considered to be heterogeneous syndromes with a complex multifactorial aetiopathogenesis, involving a highly complex and diverse combination of genetic, epigenetic and environmental factors. One such environmental factor implicated as a potential cause in both syndromes is aluminium, as an element or as part of a salt, received, for example, in oral form or as an adjuvant. Such administration has the potential to induce pathology via several routes such as provoking dysfunction and/or activation of glial cells which play an indispensable role in the regulation of central nervous system homeostasis and neurodevelopment. Other routes include the generation of oxidative stress, depletion of reduced glutathione, direct and indirect reductions in mitochondrial performance and integrity, and increasing the production of proinflammatory cytokines in both the brain and peripherally. The mechanisms whereby environmental aluminium could contribute to the development of the highly specific pattern of neuropathology seen in Alzheimer's disease are described. Also detailed are several mechanisms whereby significant quantities of aluminium introduced via immunisation could produce chronic neuropathology in genetically susceptible children. Accordingly, it is recommended that the use of aluminium salts in immunisations should be discontinued and that adults should take steps to minimise their exposure to environmental aluminium.

Modulation of neuroinflammation: Role and therapeutic potential of TRPV1 in the neuro-immune axis

Transient receptor potential vanilloid type 1 channel (TRPV1), as a ligand-gated non-selective cation channel, has recently been demonstrated to have wide expression in the neuro-immune axis, where its multiple functions occur through regulation of both neuronal and non-neuronal activities. Growing evidence has suggested that TRPV1 is functionally expressed in glial cells, especially in the microglia and astrocytes. Glial cells perform immunological functions in response to pathophysiological challenges through pro-inflammatory or anti-inflammatory cytokines and chemokines in which TRPV1 is involved. Sustaining inflammation might mediate a positive feedback loop of neuroinflammation and exacerbate neurological disorders. Accumulating evidence has suggested that TRPV1 is closely related to immune responses and might be recognized as a molecular switch in the neuroinflammation of a majority of seizures and neurodegenerative diseases. In this review, we evidenced that inflammation modulates the expression and activity of TRPV1 in the central nervous system (CNS) and TRPV1 exerts reciprocal actions over neuroinflammatory processes. Together, the literature supports the hypothesis that TRPV1 may represent potential therapeutic targets in the neuro-immune axis.

Mesenchymal stem cell-mediated immunomodulation in cell therapy of neurodegenerative diseases

Dysfunction of immune responses has been identified to involve in the pathogenesis of various neurodegenerative diseases. Abnormal activation of glia cells and/or infiltration of peripheral adaptive immune cells always sustains neuroinflammation and the disease progression. Obviously, the regulation of neuroinflammation has become a potential therapeutic strategy against neurodegenerative diseases. Mesenchymal stem cells (MSCs) exhibit complex interactions with various immune cells including T cells, macrophages and especially resident glia cells in the central nervous system. In response to tissue injury signals, MSCs adopt specific phenotype to suppress or promote immune responses depending on the inflammatory microenvironment they reside. Therefore, manipulation of MSCs may hold great potentials to improve MSC-based therapy on neurodegenerative diseases. Here we review MSC-mediated immunomodulation in cell therapy of neurodegenerative diseases, providing fundamental information for guiding appropriate applications of MSCs in clinical settings.

Interferon-β regulates the production of IL-10 by toll-like receptor-activated microglia

Pattern recognition receptors, such as toll‐like receptors (TLRs), perceive tissue alterations and initiate local innate immune responses. Microglia, the resident macrophages of the brain, encode TLRs which primary role is to protect the tissue integrity. However, deregulated activation of TLRs in microglia may lead to chronic neurodegeneration. This double role of microglial responses is often reported in immune‐driven neurologic diseases, as in multiple sclerosis (MS). Consequently, strategies to manipulate microglia inflammatory responses may help to ameliorate disease progression. In this context, the anti‐inflammatory cytokine interleukin (IL)‐10 appears as an attractive target. In this study, we investigated how activation of microglia by TLRs with distinct roles in MS impacts on IL‐10 production. We found that activation of TLR2, TLR4, and TLR9 induced the production of IL‐10 to a greater extent than activation of TLR3. This was surprising as both TLR3 and IL‐10 play protective roles in animal models of MS. Interestingly, combination of TLR3 triggering with the other TLRs, enhanced IL‐10 through the modulation of its transcription, via interferon (IFN)‐β, but independently of IL‐27. Thus, in addition to the modulation of inflammatory responses of the periphery described for the axis TLR3/IFN‐β, we now report a direct modulation of microglial responses. We further show that the presence of IFN‐γ in the microenvironment abrogated the modulation of IL‐10 by TLR3, whereas that of IL‐17 had no effect. Considering the therapeutic application of IFN‐β in MS, our study bears important implications for the understanding of the cytokine network regulating microglia responses in this setting.

Prostaglandin E2 Produced by Alginate-Encapsulated Mesenchymal Stromal Cells Modulates the Astrocyte Inflammatory Response

Astroglia are well known for their role in propagating secondary injury following brain trauma. Modulation of this injury cascade, including inflammation, is essential to repair and recovery. Mesenchymal stromal cells (MSCs) have been demonstrated as trophic mediators in several models of secondary CNS injury, however, there has been varied success with the use of direct implantation due to a failure to persist at the injury site. To achieve sustained therapeutic benefit, we have encapsulated MSCs in alginate microspheres and evaluated the ability of these encapsulated MSCs to attenuate neuro-inflammation. In this study, astroglial cultures were administered lipopolysaccharide (LPS) to induce inflammation and immediately co-cultured with encapsulated or monolayer human MSCs. Cultures were assayed for the pro-inflammatory cytokine tumor necrosis factor alpha (TNF-α) produced by astroglia, MSC-produced prostaglandin E2, and expression of neurotrophin-associated genes. We found that encapsulated MSCs significantly reduced TNF-α produced by LPS-stimulated astrocytes, more effectively than monolayer MSCs, and this enhanced benefit commences earlier than that of monolayer MSCs. Furthermore, in support of previous findings, encapsulated MSCs constitutively produced high levels of PGE2, while monolayer MSCs required the presence of inflammatory stimuli to induce PGE2 production. The early, constitutive presence of PGE2 significantly reduced astrocyte-produced TNF-α, while delayed administration had no effect. Finally, MSC-produced PGE2 was not only capable of modulating inflammation, but appears to have an additional role in stimulating astrocyte neurotrophin production. Overall, these results support the enhanced benefit of encapsulated MSC treatment, both in modulating the inflammatory response and providing neuroprotection.