CSF cytokine profile distinguishes multifocal motor neuropathy from progressive muscular atrophy

Blood-based therapies to combat neurodegenerative diseases

Neurodegeneration, known as the progressive loss of neurons in terms of their structure and function, is the principal pathophysiological change found in the majority of brain-related disorders. Ageing has been considered the most well-established risk factor in most common neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer's disease (AD). There is currently no effective treatment or cure for these diseases; the approved therapeutic options to date are only for palliative care. Ageing and neurodegenerative diseases are closely intertwined; reversing the aspects of brain ageing could theoretically mitigate age-related neurodegeneration. Ever since the regenerative properties of young blood on aged tissues came to light, substantial efforts have been focused on identifying and characterizing the circulating factors in the young and old systemic milieu that may attenuate or accentuate brain ageing and neurodegeneration. Later studies discovered the superiority of old plasma dilution in tissue rejuvenation, which is achieved through a molecular reset of the systemic proteome. These findings supported the use of therapeutic blood exchange for the treatment of degenerative diseases in older individuals. The first objective of this article is to explore the rejuvenating properties of blood-based therapies in the ageing brains and their therapeutic effects on AD. Then, we also look into the clinical applications, various limitations, and challenges associated with blood-based therapies for AD patients.

Transcriptomic Analyses of Neurotoxic Astrocytes Derived from Adult Triple Transgenic Alzheimer's Disease Mice

Neurodegenerative diseases such as Alzheimer's disease have been classically studied from a purely neuronocentric point of view. More recent evidences support the notion that other cell populations are involved in disease progression. In this sense, the possible pathogenic role of glial cells like astrocytes is increasingly being recognized. Once faced with tissue damage signals and other stimuli present in disease environments, astrocytes suffer many morphological and functional changes, a process referred as reactive astrogliosis. Studies from murine models and humans suggest that these complex and heterogeneous responses could manifest as disease-specific astrocyte phenotypes. Clear understanding of disease-associated astrocytes is a necessary step to fully disclose neurodegenerative processes, aiding in the design of new therapeutic and diagnostic strategies. In this work, we present the transcriptomics characterization of neurotoxic astrocytic cultures isolated from adult symptomatic animals of the triple transgenic mouse model of Alzheimer's disease (3xTg-AD). According to the observed profile, 3xTg-AD neurotoxic astrocytes show various reactivity features including alteration of the extracellular matrix and release of pro-inflammatory and proliferative factors that could result in harmful effects to neurons. Moreover, these alterations could be a consequence of stress responses at the endoplasmic reticulum and mitochondria as well as of concomitant metabolic adaptations. Present results support the hypothesis that adaptive changes of astrocytic function induced by a stressed microenvironment could later promote harmful astrocyte phenotypes and further accelerate or induce neurodegenerative processes.

Assessing causal relationship between circulating cytokines and age-related neurodegenerative diseases: a bidirectional two-sample Mendelian randomization analysis

Numerous studies have reported that circulating cytokines (CCs) are linked to age-related neurodegenerative diseases (ANDDs); however, there is a lack of systematic investigation for the causal association. A two-sample bidirectional Mendelian Randomisation (MR) method was utilized to evaluate the causal effect. We applied genetic variants correlated with concentrations of CCs from a genome-wide association study meta-analysis (n = 8293) as instrumental variables. Summary data of three major ANDDs [Alzheimer's disease (AD), Parkinson's disease (PD), and Amyotrophic lateral sclerosis (ALS)] were identified from the IEU OpenGWAS platform (n = 627, 266). Inverse-variance weighted method is the main approach to analyse causal effect, and MR results are verified by several sensitivity and pleiotropy analyses. In directional MR, it suggested that several CCs were nominally correlated with the risk of ANDDs, with a causal odds ratio (OR) of Interleukin (IL)-5 of 0.909 for AD; OR of IL-2 of 1.169 for PD; and OR of Beta nerve growth factor of 1.142 for ALS). In reverse MR, there were some suggestively causal effects of ANDDs on CCs (AD on increased Basic fibroblast growth factor and IL-12 and decreased Stem cell growth factor beta; PD on decreased Monokine induced by interferon-gamma; ALS on decreased Basic fibroblast growth factor and IL-17). The findings were stable across sensitivity and pleiotropy analyses. However, after Bonferroni correction, there is no statistically significant association between CCs and ANDDs. Through the genetic epidemiological approach, our study assessed the role and presented possible causal associations between CCs and ANDDs. Further studies are warranted to verify the causal associations.

Case report: Evolution of catatonic mutism and psychotic symptoms in an adolescent with Down syndrome: transition from Down syndrome disintegrative disorder to anti-N-methyl-D-aspartate receptor encephalitis

During her first year of junior high school, a 12-year-old Japanese girl with Down syndrome experienced dizziness, gait disruption, paroxysmal weakness in her hands, and sluggish speaking. Regular blood tests and a brain MRI revealed no abnormalities, and she was tentatively diagnosed with adjustment disorder. Nine months later, the patient experienced a subacute sickness of chest pain, nausea, sleep problem with night terrors, and delusion of observation. Rapid deterioration then developed with simultaneous fever, akinetic mutism, loss of facial expression, and urine incontinence. These catatonic symptoms improved after a few weeks after admission and treatment with lorazepam, escitalopram, and aripiprazole. After discharge, nonetheless, daytime slumber, empty eyes, paradoxical laughter, and declined verbal communication persisted. Upon confirmation of the cerebrospinal N-methyl-D-aspartate (NMDA) receptor autoantibody, methylprednisolone pulse therapy was tried, but it had little effect. Visual hallucinations and cenesthopathy, as well as suicidal thoughts and delusions of death, have predominated in the following years. Cerebrospinal IL-1ra, IL-5, IL-15, CCL5, G-CSF, PDGFbb, and VFGF were raised in the early stage of initial medical attention with nonspecific complaints, but were less prominent in the later stages of catatonic mutism and psychotic symptoms. We suggest a disease concept of progression from Down syndrome disintegrative disorder to NMDA receptor encephalitis, based on this experience.

Multifocal motor neuropathy is not associated with altered innate immune responses to endotoxin

OBJECTIVE

Antibody- and complement-mediated peripheral nerve inflammation are central in the pathogenesis of MMN. Here, we studied innate immune responses to endotoxin in patients with MMN and controls to further our understanding of MMN risk factors and disease modifiers.

METHODS

We stimulated whole blood of 52 patients with MMN and 24 controls with endotoxin and collected plasma. With a multiplex assay, we determined levels of the immunoregulating proteins IL-1RA, IL-1β, IL-6, IL-10, IL-21, TNF-α, IL-8 and CD40L in unstimulated and LPS-stimulated plasma. We compared baseline and stimulated protein levels between patients and controls and correlated concentrations to clinical parameters.

RESULTS

Protein level changes after stimulation were comparable between groups (p > 0.05). IL-1RA, IL-1β, IL-6 and IL-21 baseline concentrations showed a positive correlation with monthly IVIg dosage (all corrected p-values < 0.016). Patients with anti-GM1 IgM antibodies showed a more pronounced IL-21 increase after stimulation (p 0.048).

CONCLUSIONS

Altered endotoxin-induced innate immune responses are unlikely to be a susceptibility factor for MMN.

Intramuscular IL-10 Administration Enhances the Activity of Myogenic Precursor Cells and Improves Motor Function in ALS Mouse Model

Amyotrophic Lateral Sclerosis (ALS) is the most common adult motor neuron disease, with a poor prognosis, a highly unmet therapeutic need, and a burden on health care costs. Hitherto, strategies aimed at protecting motor neurons have missed or modestly delayed ALS due to a failure in countering the irreversible muscular atrophy. We recently provided direct evidence underlying the pivotal role of macrophages in preserving skeletal muscle mass. Based on these results, we explored whether the modulation of macrophage muscle response and the enhancement of satellite cell differentiation could effectively promote the generation of new myofibers and counteract muscle dysfunction in ALS mice. For this purpose, disease progression and the survival of SOD1G93A mice were evaluated following IL-10 injections in the hindlimb skeletal muscles. Thereafter, we used ex vivo methodologies and in vitro approaches on primary cells to assess the effect of the treatment on the main pathological signatures. We found that IL-10 improved the motor performance of ALS mice by enhancing satellite cells and the muscle pro-regenerative activity of macrophages. This resulted in delayed muscle atrophy and motor neuron loss. Our findings provide the basis for a suitable adjunct multisystem therapeutic approach that pinpoints a primary role of muscle pathology in ALS.

Proinflammatory IL-17 levels in serum/cerebrospinal fluid of patients with neurodegenerative diseases: a meta-analysis study

IL-17 is one of the major proinflammatory cytokine implicated in the pathophysiology of various chronic inflammatory diseases. However, a clear association between the levels of IL-17 and various neurodegenerative diseases is inconclusive due to lack of consistent results reported in several studies. Therefore, we designed and performed a meta-analysis study to assess the levels of IL-17 cytokine in various neurodegenerative diseases. The aim of this meta-analysis study was to assess the level of IL-17 in cerebrospinal fluid/serum of the patients with neurodegenerative diseases such as Alzheimer's disease, Parkinson disease, multiple sclerosis, and amyotrophic lateral sclerosis. An extensive search was performed on electronic databases including PubMed, Cochrane, and Google Scholar to find out the relevant studies for analysis. The quality of selected studies was assessed by Newcastle-Ottawa scale for cohort and case control studies. The standardized mean difference of level of IL-17 in patients with neurodegenerative diseases and control was calculated using RevMan 5 software. A significant increase in the level of serum IL-17 was found to in the patients with neurodegenerative diseases like Alzheimer's disease (p = 0.001) and amyotrophic lateral sclerosis (p = 0.009), whereas IL-17 level in serum of Parkinson's disease (p = 0.22), multiple sclerosis (p = 0.09), and in peripheral blood mononuclear cells of MS patients (p = 0.34) was not found to be significant. IL-17 may be involved in regulation of neuronal inflammation during the pathogenesis of these neurodegenerative disease, and its specific inhibition could be a potential therapeutic target.

Therapeutic potential of targeting IL-17 and its receptor signaling in neuroinflammation

T helper 17 cells are thought to significantly contribute to the neuroinflammation process during neurogenerative diseases via their signature cytokine, interleukin (IL)-17. Recently, an emerging key role of IL-17 and its receptors has been documented in inflammatory and autoimmune diseases. The clinical studies conducted on patients with neurodegenerative disease have also shown an increase in IL-17 levels in serum as well as cerebrospinal fluid samples. Therapeutic targeting of either IL-17 receptors or direct IL-17 neutralizing antibodies has shown a promising preclinical and clinical proof of concept for treating chronic autoimmune neurodegenerative diseases such as multiple sclerosis. Thus, IL-17 and its receptors have a central role in regulation of neuroinflammation and can be considered as one of the major therapeutic targets in chronic neuroinflammatory diseases.

Inflammatory checkpoints in amyotrophic lateral sclerosis: From biomarkers to therapeutic targets

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive motor neuron damage. Due to the complexity of the ALS, so far the etiology and underlying pathogenesis of sporadic ALS are not completely understood. Recently, many studies have emphasized the role of inflammatory networks, which are comprised of various inflammatory molecules and proteins in the pathogenesis of ALS. Inflammatory molecules and proteins may be used as independent predictors of patient survival and might be used in patient stratification and in evaluating the therapeutic response in clinical trials. This review article describes the latest advances in various inflammatory markers in ALS and its animal models. In particular, this review discusses the role of inflammatory molecule markers in the pathogenesis of the disease and their relationship with clinical parameters. We also highlight the advantages and disadvantages of applying inflammatory markers in clinical manifestations, animal studies, and drug clinical trials. Further, we summarize the potential application of some inflammatory biomarkers as new therapeutic targets and therapeutic strategies, which would perhaps expand the therapeutic interventions for ALS.

Cerebrospinal fluid biomarkers of disease activity and progression in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a relentlessly progressive neurodegenerative disease, and only modest disease-modifying strategies have been established to date. Numerous clinical trials have been conducted in the past years, but have been severely hampered by the wide-ranging heterogeneity of both the biological origins and clinical characteristics of the disease. Thus, reliable biomarkers of disease activity are urgently needed to stratify patients into homogenous groups with aligned disease trajectories to allow a more effective design of clinical trial. In this review, the most promising candidate biomarkers in the cerebrospinal fluid (CSF) of patients with ALS will be summarised. Correlations between biomarker levels and clinical outcome parameters are discussed, while highlighting potential pitfalls and intercorrelations of these clinical parameters. Several CSF molecules have shown potential as biomarkers of progression and prognosis, but large, international, multicentric and longitudinal studies are crucial for validation. A more standardised choice of clinical endpoints in these studies, as well as the application of individualised models of clinical progression, would allow the quantification of disease trajectories, thereby allowing a more accurate analysis of the clinical implications of candidate biomarkers. Additionally, a comparative analysis of several biomarkers and ideally the application of a multivariate analysis including comprehensive genotypic, phenotypic and clinical characteristics collectively contributing to biomarker levels in the CSF, could promote their verification. Thus, reliable prognostic markers and markers of disease activity may improve clinical trial design and patient management in the direction of precision medicine.

Intranasal insulin modulates cerebrospinal fluid markers of neuroinflammation in mild cognitive impairment and Alzheimer's disease: a randomized trial

Intranasal insulin (INI) has shown promise as a treatment for Alzheimer's disease (AD) in pilot clinical trials. In a recent phase 2 trial, participants with mild cognitive impairment (MCI) or AD who were treated with INI with one of two delivery devices showed improved cerebral spinal fluid (CSF) biomarker profiles and slower symptom progression compared with placebo. In the cohort which showed benefit, we measured changes in CSF markers of inflammation, immune function and vascular integrity and assessed their relationship with changes in cognition, brain volume, and CSF amyloid and tau concentrations. The insulin-treated group had increased CSF interferon-γ (p = 0.032) and eotaxin (p = 0.049), and reduced interleukin-6 (p = 0.048) over the 12 month trial compared to placebo. Trends were observed for increased CSF macrophage-derived chemokine for the placebo group (p = 0.083), and increased interleukin-2 in the insulin-treated group (p = 0.093). Insulin-treated and placebo groups showed strikingly different patterns of associations between changes in CSF immune/inflammatory/vascular markers and changes in cognition, brain volume, and amyloid and tau concentrations. In summary, INI treatment altered the typical progression of markers of inflammation and immune function seen in AD, suggesting that INI may promote a compensatory immune response associated with therapeutic benefit.

Neuroinflammation in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia and the Interest of Induced Pluripotent Stem Cells to Study Immune Cells Interactions With Neurons

Inflammation is a shared hallmark between amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). For long, studies were conducted on tissues of post-mortem patients and neuroinflammation was thought to be only bystander result of the disease with the immune system reacting to dying neurons. In the last two decades, thanks to improving technologies, the identification of causal genes and the development of new tools and models, the involvement of inflammation has emerged as a potential driver of the diseases and evolved as a new area of intense research. In this review, we present the current knowledge about neuroinflammation in ALS, ALS-FTD, and FTD patients and animal models and we discuss reasons of failures linked to therapeutic trials with immunomodulator drugs. Then we present the induced pluripotent stem cell (iPSC) technology and its interest as a new tool to have a better immunopathological comprehension of both diseases in a human context. The iPSC technology giving the unique opportunity to study cells across differentiation and maturation times, brings the hope to shed light on the different mechanisms linking neurodegeneration and activation of the immune system. Protocols available to differentiate iPSC into different immune cell types are presented. Finally, we discuss the interest in studying monocultures of iPS-derived immune cells, co-cultures with neurons and 3D cultures with different cell types, as more integrated cellular approaches. The hope is that the future work with human iPS-derived cells helps not only to identify disease-specific defects in the different cell types but also to decipher the synergistic effects between neurons and immune cells. These new cellular tools could help to find new therapeutic approaches for all patients with ALS, ALS-FTD, and FTD.

Inflammatory Chemokines Expression Variations and Their Receptors in APP/PS1 Mice

BACKGROUND

In Alzheimer's disease (AD), an increase in inflammation is distinctive. Amyloid precursor protein plus presenilin-1 (APP/PS1 mice) is a model for this illness. Chemokines secreted by central nervous system (CNS) cells could play multiple important roles in AD. Data looking for the chemokines involved in inflammatory mechanisms are lacking. To understand the changes that occur in the inflammation process in AD, it is necessary to improve strategies to act on specific inflammatory targets.

OBJECTIVE

Chemokines and their receptors involved in phagocytosis, demyelination, chemotaxis, and coagulation were the objective of our study.

METHODS

Female APPswe/PS1 double-transgenic mice (B6C3-Tg) were used and cortex brain from 20-22-month-old mice obtained and used to quantify chemokines and chemokine receptors expression using RT-PCR technique.

RESULTS

Significant inflammatory changes were detected in APP/PS1 compared to wild type mice. CCR1, CCR3, CCR4, and CCR9 were elevated, and CCR2 were decreased compared with wild type mice. Their ligands CCL7, CCL11, CCL17, CCL22, CCL25, and CXCL4 showed an increase expression; however, changes were not observed in CCL2 in APP/PS1 compared to wild type mice.

CONCLUSION

This change in expression could explain the differences between AD patients and elderly people without this illness. This would provide a new strategy for the treatment of AD, with the possibility to act in specific inflammatory targets.

Interplay between immunity and amyotrophic lateral sclerosis: Clinical impact

Amyotrophic lateral sclerosis (ALS) is a debilitating and rapidly fatal neurodegenerative disease. Despite decades of research and many new insights into disease biology over the 150 years since the disease was first described, causative pathogenic mechanisms in ALS remain poorly understood, especially in sporadic cases. Our understanding of the role of the immune system in ALS pathophysiology, however, is rapidly expanding. The aim of this manuscript is to summarize the recent advances regarding the immune system involvement in ALS, with particular attention to clinical translation. We focus on the potential pathophysiologic mechanism of the immune system in ALS, discussing local and systemic factors (blood, cerebrospinal fluid, and microbiota) that influence ALS onset and progression in animal models and people. We also explore the potential of Positron Emission Tomography to detect neuroinflammation in vivo, and discuss ongoing clinical trials of therapies targeting the immune system. With validation in human patients, new evidence in this emerging field will serve to identify novel therapeutic targets and provide realistic hope for personalized treatment strategies.

Increased synthesis of pro-inflammatory cytokines in C9ORF72 patients

C9ORF72 hexanucleotide expansion is the most common genetic cause of familial amyotrophic lateral sclerosis (ALS)/fronto-temporal dementia (FTD) disease spectrum. Even though three major mechanisms of disease pathogenesis have been proposed, we lack detailed understanding of the factors that influence disease onset and progression. We sought to characterize cerebrospinal fluid and sera of C9ORF72 patients via a multiplex assay of 41 chemokines and cytokines in comparison to neurological controls and sporadic ALS patients. We found an increase in synthesis of pro-inflammatory chemokines and cytokines in disease samples and particularly in C9ORF72 patients in comparison to controls. We provide evidence that a CSF pro-inflammatory signature is a feature of C9ORF72-mediated disease.

From Multi-Omics Approaches to Precision Medicine in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating and fatal neurodegenerative disorder, caused by the degeneration of upper and lower motor neurons for which there is no truly effective cure. The lack of successful treatments can be well explained by the complex and heterogeneous nature of ALS, with patients displaying widely distinct clinical features and progression patterns, and distinct molecular mechanisms underlying the phenotypic heterogeneity. Thus, stratifying ALS patients into consistent and clinically relevant subgroups can be of great value for the development of new precision diagnostics and targeted therapeutics for ALS patients. In the last years, the use and integration of high-throughput "omics" approaches have dramatically changed our thinking about ALS, improving our understanding of the complex molecular architecture of ALS, distinguishing distinct patient subtypes and providing a rational foundation for the discovery of biomarkers and new individualized treatments. In this review, we discuss the most significant contributions of omics technologies in unraveling the biological heterogeneity of ALS, highlighting how these approaches are revealing diagnostic, prognostic and therapeutic targets for future personalized interventions.

Immunity in amyotrophic lateral sclerosis: blurred lines between excessive inflammation and inefficient immune responses

Despite wide genetic, environmental and clinical heterogeneity in amyotrophic lateral sclerosis, a rapidly fatal neurodegenerative disease targeting motoneurons, neuroinflammation is a common finding. It is marked by local glial activation, T cell infiltration and systemic immune system activation. The immune system has a prominent role in the pathogenesis of various chronic diseases, hence some of them, including some types of cancer, are successfully targeted by immunotherapeutic approaches. However, various anti-inflammatory or immunosuppressive therapies in amyotrophic lateral sclerosis have failed. This prompted increased scrutiny over the immune-mediated processes underlying amyotrophic lateral sclerosis. Perhaps the biggest conundrum is that amyotrophic lateral sclerosis pathogenesis exhibits features of three otherwise distinct immune dysfunctions-excessive inflammation, autoimmunity and inefficient immune responses. Epidemiological and genome-wide association studies show only minimal overlap between amyotrophic lateral sclerosis and autoimmune diseases, so excessive inflammation is usually thought to be secondary to protein aggregation, mitochondrial damage or other stresses. In contrast, several recently characterized amyotrophic lateral sclerosis-linked mutations, including those in TBK1, OPTN, CYLD and C9orf72, could lead to inefficient immune responses and/or damage pile-up, suggesting that an innate immunodeficiency may also be a trigger and/or modifier of this disease. In such cases, non-selective immunosuppression would further restrict neuroprotective immune responses. Here we discuss multiple layers of immune-mediated neuroprotection and neurotoxicity in amyotrophic lateral sclerosis. Particular focus is placed on individual patient mutations that directly or indirectly affect the immune system, and the mechanisms by which these mutations influence disease progression. The topic of immunity in amyotrophic lateral sclerosis is timely and relevant, because it is one of the few common and potentially malleable denominators in this heterogenous disease. Importantly, amyotrophic lateral sclerosis progression has recently been intricately linked to patient T cell and monocyte profiles, as well as polymorphisms in cytokine and chemokine receptors. For this reason, precise patient stratification based on immunophenotyping will be crucial for efficient therapies.

The Regulatory Role of IL-10 in Neurodegenerative Diseases

IL-10, an immunosuppressive cytokine, is considered an important anti-inflammatory modulator of glial activation, preventing inflammation-mediated neuronal degeneration under pathological conditions. In this narrative review, we summarize recent insights about the role of IL-10 in the neurodegeneration associated with neuroinflammation, in diseases such as Multiple Sclerosis, Traumatic Brain Injury, Amyotrophic lateral sclerosis, Alzheimer’s Disease, and Parkinson’s Disease, focusing on the contribution of this cytokine not only in terms of protective action, but also as possibly responsible for clinical worsening. The knowledge of this double face of the same coin, regarding the biological role of the IL-10, could aid the development of targeted therapies useful for limiting neurodegenerative processes.

CCL11 Differentially Affects Post-Stroke Brain Injury and Neuroregeneration in Mice Depending on Age

CCL11 has recently been shown to differentially affect cell survival under various pathological conditions including stroke. Indeed, CCL11 promotes neuroregeneration in neonatal stroke mice. The impact of CCL11 on the adult ischemic brain, however, remains elusive. We therefore studied the effect of ectopic CCL11 on both adolescent (six-week) and adult (six-month) C57BL6 mice exposed to stroke. Intraperitoneal application of CCL11 significantly aggravated acute brain injury in adult mice but not in adolescent mice. Likewise, post-stroke neurological recovery after four weeks was significantly impaired in adult mice whilst CCL11 was present. On the contrary, CCL11 stimulated gliogenesis and neurogenesis in adolescent mice. Flow cytometry analysis of blood and brain samples revealed a modification of inflammation by CCL11 at subacute stages of the disease. In adolescent mice, CCL11 enhances microglial cell, B and T lymphocyte migration towards the brain, whereas only the number of B lymphocytes is increased in the adult brain. Finally, the CCL11 inhibitor SB297006 significantly reversed the aforementioned effects. Our study, for the first time, demonstrates CCL11 to be a key player in mediating secondary cell injury under stroke conditions. Interfering with this pathway, as shown for SB297006, might thus be an interesting approach for future stroke treatment paradigms.

Are Circulating Cytokines Reliable Biomarkers for Amyotrophic Lateral Sclerosis?

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that has no effective treatment. The lack of any specific biomarker that can help in the diagnosis or prognosis of ALS has made the identification of biomarkers an urgent challenge. Multiple panels have shown alterations in levels of numerous cytokines in ALS, supporting the contribution of neuroinflammation to the progressive motor neuron loss. However, none of them is fully sensitive and specific enough to become a universal biomarker for ALS. This review gathers the numerous circulating cytokines that have been found dysregulated in both ALS animal models and patients. Particularly, it highlights the opposing results found in the literature to date, and points out another potential application of inflammatory cytokines as therapeutic targets.

Circulating Cytokines Could Not Be Good Prognostic Biomarkers in a Mouse Model of Amyotrophic Lateral Sclerosis

Background: There is growing evidence of the role of inflammation in Amyotrophic Lateral Sclerosis (ALS) during the last decade. Although the origin of ALS remains unknown, multiple potential inflammatory biomarkers have been described in ALS patients and murine models of this disease to explain the progressive motor neuron loss and muscle atrophy. However, the results remain controversial. To shed light on this issue, we aimed to identify novel biomarkers of inflammation that can influence disease progression and survival in serial blood samples from transgenic SOD1G93A mice, a model of ALS. Methods: A cytokine array assay was performed to analyze protein expression of 97 cytokines in plasma samples from wildtype controls and transgenic SOD1G93A mice at asymptomatic stage. Subsequently, serial plasma samples were obtained from SOD1G93A mice at early symptomatic, symptomatic and terminal stages to monitor cytokine levels during disease progression through immunoassays. Comparisons of means of quantifiable cytokines between short-and long-lived mice were analyzed by unrelated t-test or Mann-Whitney U-test. Relationships between cytokines levels and survival time were assessed using Pearson's correlation analysis and Kaplan-Meier analysis. Results: A total of 16 cytokines (6Ckine, ALK-1, CD30 L, eotaxin-1, galectin-1, GITR, IL-2, IL-6, IL-10, IL-13, IL-17B R, MIP-1α, MIP-3β, RANKL, TROY, and VEGF-D) were found dysregulated in transgenic SOD1G93A mice at asymptomatic stage compared with age-matched controls. Immunoassays of serial samples revealed positive expression of ALK-1, GITR and IL-17B R at P60 and P90 in mice with shorter survival. In addition, eotaxin-1 and galectin-1 levels were significantly increased at terminal stage in SOD1G93A mice that showed shorter survival time. Finally, levels of eotaxin-1, galectin-1, IL-2, IL-6, MIP-1α, and TROY at P90 or endpoint negatively correlated with the longevity of transgenic mice. Conclusions: We demonstrated in the SOD1G93A model of ALS that increased levels of several cytokines were associated with a shorter lifespan. However, their role as prognostic biomarkers is unclear as their expression was very variable depending on both the disease stage and the subject. Nevertheless, cytokines may be potential therapeutic targets.

Increased IP-10 production by blood-nerve barrier in multifocal acquired demyelinating sensory and motor neuropathy and multifocal motor neuropathy

OBJECTIVE

Dysfunction of the blood-nerve barrier (BNB) plays important roles in chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN). The aim of the present study was to identify the candidate cytokines/chemokines that cause the breakdown of the BNB using sera from patients with CIDP and MMN.

METHODS

We determined the levels of 27 cytokines and chemokines in human peripheral nerve microvascular endothelial cells (PnMECs) after exposure to sera obtained from patients with CIDP variants (typical CIDP and multifocal acquired demyelinating sensory and motor neuropathy [MADSAM]), MMN and amyotrophic lateral sclerosis (ALS), and healthy controls (HC), using a multiplexed fluorescent bead-based immunoassay system.

RESULTS

The induced protein (IP)10 level in the cells in both the MADSAM and MMN groups was markedly increased in comparison with the typical CIDP, ALS and HC groups. The other cytokines, including granulocyte colony-stimulating factor,vascular endothelial growth factor (VEGF) and interleukin-7, were also significantly upregulated in the MADSAM group. The increase of IP-10 produced by PnMECs was correlated with the presence of conduction block in both the MADSAM and MMN groups.

CONCLUSION

The autocrine secretion of IP-10 induced by patient sera in PnMECs was markedly upregulated in both the MADSAM and MMN groups. The overproduction of IP-10 by PnMECs leads to the focal breakdown of the BNB and may help to mediate the transfer of pathogenic T cells across the BNB, thereby resulting in the appearance of conduction block in electrophysiological studies of patients with MADSAM and MMN.

Atypical Motor Neuron Disease variants: Still a diagnostic challenge in Neurology

Motor neuron disease (MND) represents a wide and heterogeneous expanding group of disorders involving the upper or lower motor neurons, mainly represented by amyotrophic lateral sclerosis (ALS), primary lateral sclerosis, progressive muscular atrophy and progressive bulbar palsy. Primary motor neuronopathies are characterized by progressive degenerative loss of anterior horn cell motoneurons (lower motor neurons) or loss of giant pyramidal Betz cells (upper motor neurons). Despite its well-known natural history, pathophysiological and clinical characteristics for the most common MND, atypical clinical presentation and neurodegenerative mechanisms are commonly observed in rare clinical entities, so-called atypical variants of MND-ALS, including flail-leg syndrome, flail-arm syndrome, facial-onset sensory and motor neuronopathy (FOSMN), finger extension weakness and downbeat nystagmus (FEWDON-MND) and long-lasting and juvenile MND-ALS. Herein, we provide a review article presenting clinical, genetic, pathophysiological and neuroimaging findings of atypical variants of MND-ALS in clinical practice.

Biomarker Supervised G-CSF (Filgrastim) Response in ALS Patients

Objective: To evaluate safety, tolerability and feasibility of long-term treatment with Granulocyte-colony stimulating factor (G-CSF), a well-known hematopoietic stem cell factor, guided by assessment of mobilized bone marrow derived stem cells and cytokines in the serum of patients with amyotrophic lateral sclerosis (ALS) treated on a named patient basis.

Methods: 36 ALS patients were treated with subcutaneous injections of G-CSF on a named patient basis and in an outpatient setting. Drug was dosed by individual application schemes (mean 464 Mio IU/month, range 90-2160 Mio IU/month) over a median of 13.7 months (range from 2.7 to 73.8 months). Safety, tolerability, survival and change in ALSFRS-R were observed. Hematopoietic stem cells were monitored by flow cytometry analysis of circulating CD34⁺ and CD34⁺CD38⁻ cells, and peripheral cytokines were assessed by electrochemoluminescence throughout the intervention period. Analysis of immunological and hematological markers was conducted.

Results: Long term and individually adapted treatment with G-CSF was well tolerated and safe. G-CSF led to a significant mobilization of hematopoietic stem cells into the peripheral blood. Higher mobilization capacity was associated with prolonged survival. Initial levels of serum cytokines, such as MDC, TNF-beta, IL-7, IL-16, and Tie-2 were significantly associated with survival. Continued application of G-CSF led to persistent alterations in serum cytokines and ongoing measurements revealed the multifaceted effects of G-CSF.

Conclusions: G-CSF treatment is feasible and safe for ALS patients. It may exert its beneficial effects through neuroprotective and -regenerative activities, mobilization of hematopoietic stem cells and regulation of pro- and anti-inflammatory cytokines as well as angiogenic factors. These cytokines may serve as prognostic markers when measured at the time of diagnosis. Hematopoietic stem cell numbers and cytokine levels are altered by ongoing G-CSF application and may potentially serve as treatment biomarkers for early monitoring of G-CSF treatment efficacy in ALS in future clinical trials.

Cerebrospinal fluid and blood biomarkers for neurodegenerative dementias: An update of the Consensus of the Task Force on Biological Markers in Psychiatry of the World Federation of Societies of Biological Psychiatry

In the 12 years since the publication of the first Consensus Paper of the WFSBP on biomarkers of neurodegenerative dementias, enormous advancement has taken place in the field, and the Task Force takes now the opportunity to extend and update the original paper. New concepts of Alzheimer's disease (AD) and the conceptual interactions between AD and dementia due to AD were developed, resulting in two sets for diagnostic/research criteria. Procedures for pre-analytical sample handling, biobanking, analyses and post-analytical interpretation of the results were intensively studied and optimised. A global quality control project was introduced to evaluate and monitor the inter-centre variability in measurements with the goal of harmonisation of results. Contexts of use and how to approach candidate biomarkers in biological specimens other than cerebrospinal fluid (CSF), e.g. blood, were precisely defined. Important development was achieved in neuroimaging techniques, including studies comparing amyloid-β positron emission tomography results to fluid-based modalities. Similarly, development in research laboratory technologies, such as ultra-sensitive methods, raises our hopes to further improve analytical and diagnostic accuracy of classic and novel candidate biomarkers. Synergistically, advancement in clinical trials of anti-dementia therapies energises and motivates the efforts to find and optimise the most reliable early diagnostic modalities. Finally, the first studies were published addressing the potential of cost-effectiveness of the biomarkers-based diagnosis of neurodegenerative disorders.

PDGF/PDGFR axis in the neural systems

Platelet-derived growth factors (PDGFs) and their receptors (PDGFRs) are expressed in several cell types including the brain cells such as neuronal progenitors, neurons, astrocytes, and oligodendrocytes. Emerging evidence shows that PDGF-mediated signaling regulates diverse functions in the central nervous system (CNS) such as neurogenesis, cell survival, synaptogenesis, modulation of ligand-gated ion channels, and development of specific types of neurons. Interestingly, PDGF/PDFGR signaling can elicit paradoxical roles in the CNS, depending on the cell type and the activation stimuli and is implicated in the pathogenesis of various neurodegenerative diseases. This review summarizes the role of PDGFs/PDGFRs in several neurodegenerative diseases such as Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, brain cancer, cerebral ischemia, HIV-1 and drug abuse. Understanding PDGF/PDGFR signaling may lead to novel approaches for the future development of therapeutic strategies for combating CNS pathologies.

CCL11 is increased in the CNS in chronic traumatic encephalopathy but not in Alzheimer's disease

CCL11, a protein previously associated with age-associated cognitive decline, is observed to be increased in the brain and cerebrospinal fluid (CSF) in chronic traumatic encephalopathy (CTE) compared to Alzheimer's disease (AD). Using a cohort of 23 deceased American football players with neuropathologically verified CTE, 50 subjects with neuropathologically diagnosed AD, and 18 non-athlete controls, CCL11 was measured with ELISA in the dorsolateral frontal cortex (DLFC) and CSF. CCL11 levels were significantly increased in the DLFC in subjects with CTE (fold change = 1.234, p < 0.050) compared to non-athlete controls and AD subjects with out a history of head trauma. This increase was also seen to correlate with years of exposure to American football (β = 0.426, p = 0.048) independent of age (β = -0.046, p = 0.824). Preliminary analyses of a subset of subjects with available post-mortem CSF showed a trend for increased CCL11 among individuals with CTE (p = 0.069) mirroring the increase in the DLFC. Furthermore, an association between CSF CCL11 levels and the number of years exposed to football (β = 0.685, p = 0.040) was observed independent of age (β = -0.103, p = 0.716). Finally, a receiver operating characteristic (ROC) curve analysis demonstrated CSF CCL11 accurately distinguished CTE subjects from non-athlete controls and AD subjects (AUC = 0.839, 95% CI 0.62-1.058, p = 0.028). Overall, the current findings provide preliminary evidence that CCL11 may be a novel target for future CTE biomarker studies.

CCL11 promotes migration and proliferation of mouse neural progenitor cells

BACKGROUND

Neonatal hypoxia-ischemia induces massive brain damage during the perinatal period, resulting in long-term consequences to central nervous system structural and functional maturation. Although neural progenitor cells (NPCs) migrate through the parenchyma and home in to injury sites in the rodent brain, the molecular mechanisms are unknown. We examined the role of chemokines in mediating NPC migration after neonatal hypoxic-ischemic brain injury.

METHODS

Nine-day-old mice were exposed to a 120-minute hypoxia following unilateral carotid occlusion. Chemokine levels were quantified in mouse brain extract. Migration and proliferation assays were performed using embryonic and infant mouse NPCs.

RESULTS

The neonatal hypoxic-ischemic brain injury resulted in an ipsilateral lesion, which was extended to the cortical and striatal areas. NPCs migrated toward an injured area, where a marked increase of CC chemokines was detected. In vitro studies showed that incubation of NPCs with recombinant mouse CCL11 promoted migration and proliferation. These effects were partly inhibited by a CCR3 antagonist, SB297006.

CONCLUSIONS

Our data implicate an important effect of CCL11 for mouse NPCs. The effective activation of NPCs may offer a promising strategy for neuroregeneration in neonatal hypoxic-ischemic brain injury.

Cerebrospinal fluid from patients with amyotrophic lateral sclerosis inhibits sonic hedgehog function

Sonic hedgehog (Shh) is a morphogen essential to the developing nervous system that continues to play an important role in adult life by contributing to cell proliferation and differentiation, maintaining blood-brain barrier integrity, and being cytoprotective against oxidative and excitotoxic stress, all features of importance in amyotrophic lateral sclerosis (ALS). ALS is a fatal disease characterized by selective loss of motor neurons due to poorly understood mechanisms. Evidence indicates that Shh might play an important role in ALS, and that Shh signaling might be also adversely affected in ALS. Since little is known about the functional status of Shh pathway in patients with ALS, we therefore sought to determine whether Shh protein levels or biological activity in cerebrospinal fluid (CSF) was less in ALS patients than controls, and whether these measures could be correlated with ALS disease severity and disease progression, and with other CSF analytes of biological interest in ALS. Comparing Shh levels in the CSF of normal controls (n = 13), neurological controls (n = 12), and ALS patients (n = 9) measured by ELISA, we found that CSF Shh levels were not different between controls and ALS patients. However, when assessing Shh biological activity in CSF using in vitro cell-based assays, which measure Shh activity as inducible Gli-driven luminescence, we found that in the presence of exogenous recombinant Shh or the Shh agonist, purmorphamine, the inducible activity of CSF was significantly augmented in the control groups as expected, but not in the ALS group, suggesting the presence of an inhibitor of Shh signaling in ALS CSF samples. Since purmorphamine acts on Smoothened, downstream of Shh and its receptor Patched, the inhibitory action is downstream of Smoothened. Our results also demonstrated that while the inhibitory effect of ALS CSF on Shh signaling did not correlate significantly with ALS disease characteristics, the levels of IL-1β and TNF-α did. In addition to being significantly elevated in ALS CSF, these cytokines negatively correlated with the disease duration, whereas GDF11 was a favorable predictor of ALS clinical score. We also found that TNF-α significantly inhibited Shh biological activity in vitro, potentially suggesting a novel role of TNF-α in ALS pathogenesis. Collectively, this is the first report demonstrating that Shh signaling in CSF of ALS patients is compromised.

Glial biomarkers in human central nervous system disease

There is a growing understanding that aberrant GLIA function is an underlying factor in psychiatric and neurological disorders. As drug discovery efforts begin to focus on glia-related targets, a key gap in knowledge includes the availability of validated biomarkers to help determine which patients suffer from dysfunction of glial cells or who may best respond by targeting glia-related drug mechanisms. Biomarkers are biological variables with a significant relationship to parameters of disease states and can be used as surrogate markers of disease pathology, progression, and/or responses to drug treatment. For example, imaging studies of the CNS enable localization and characterization of anatomical lesions without the need to isolate tissue for biopsy. Many biomarkers of disease pathology in the CNS involve assays of glial cell function and/or response to injury. Each major glia subtype (oligodendroglia, astroglia and microglia) are connected to a number of important and useful biomarkers. Here, we describe current and emerging glial based biomarker approaches for acute CNS injury and the major categories of chronic nervous system dysfunction including neurodegenerative, neuropsychiatric, neoplastic, and autoimmune disorders of the CNS. These descriptions are highlighted in the context of how biomarkers are employed to better understand the role of glia in human CNS disease and in the development of novel therapeutic treatments. GLIA 2016;64:1755-1771.

Immunological studies of cerebrospinal fluid from patients with CNS symptoms after human papillomavirus vaccination

In 32 patients with prolonged central nervous system symptoms after human papillomavirus (HPV) vaccination, we measured conventional and immunological markers in cerebrospinal fluid (CSF) and compared with the levels in disease controls. Our studies revealed significantly decreased chloride and neuron-specific enolase (NSE) levels in CSF of patients with CNS symptoms after HPV vaccination compared to disease controls. IL-4, IL-13, and CD4(+) T cells increased significantly in patients, and IL-17 increased significantly from 12 to 24months after symptom onset. Chemokines (IL-8 and MCP-1) were also elevated, but CD8(+) T cells, PDGF-bb and IL-12 were reduced. Antibodies to GluN2B-NT2, GluN2B-CT and GluN1-NT increased significantly. These results suggest biological, mainly immunological, changes in the CSF of patients after HPV vaccination.

Further development of biomarkers in amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is an idiopathic neurodegenerative disease usually fatal in less than three years. Even if standard guidelines are available to diagnose ALS, the mean diagnosis delay is more than one year. In this context, biomarker discovery is a priority. Research has to focus on new diagnostic tools, based on combined explorations.

AREAS COVERED

In this review, we specifically focus on biology and imaging markers. We detail the innovative field of 'omics' approach and imaging and explain their limits to be useful in routine practice. We describe the most relevant biomarkers and suggest some perspectives for biomarker research. Expert commentary: The successive failures of clinical trials in ALS underline the need for new strategy based on innovative tools to stratify patients and to evaluate their responses to treatment. Biomarker data may be useful to improve the designs of clinical trials. Biomarkers are also needed to better investigate disease pathophysiology, to identify new therapeutic targets, and to improve the performance of clinical assessments for diagnosis and prognosis in the clinical setting. A consensus on the best management of neuroimaging and 'omics' methods is necessary and a systematic independent validation of findings may add robustness to future studies.