Regulatory T lymphocytes from ALS mice suppress microglia and effector T lymphocytes through different cytokine-mediated mechanisms

Brain-body mechanisms contribute to sexual dimorphism in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common form of human motor neuron disease. It is characterized by the progressive degeneration of upper and lower motor neurons, leading to generalized motor weakness and, ultimately, respiratory paralysis and death within 3-5 years. The disease is shaped by genetics, age, sex and environmental stressors, but no cure or routine biomarkers exist for the disease. Male individuals have a higher propensity to develop ALS, and a different manifestation of the disease phenotype, than female individuals. However, the mechanisms underlying these sex differences remain a mystery. In this Review, we summarize the epidemiology of ALS, examine the sexually dimorphic presentation of the disease and highlight the genetic variants and molecular pathways that might contribute to sex differences in humans and animal models of ALS. We advance the idea that sexual dimorphism in ALS arises from the interactions between the CNS and peripheral organs, involving vascular, metabolic, endocrine, musculoskeletal and immune systems, which are strikingly different between male and female individuals. Finally, we review the response to treatments in ALS and discuss the potential to implement future personalized therapeutic strategies for the disease.

Human CD4+CD25+ T cells expressing a chimeric antigen receptor against aberrant superoxide dismutase 1 trigger antigen-specific immunomodulation

BACKGROUND AIMS

Amyotrophic lateral sclerosis (ALS) is a fatal disease associated with motor neuron degeneration, accumulation of aggregated misfolded proteins and neuroinflammation in motor regions of the central nervous system (CNS). Clinical trials using regulatory T cells (Tregs) are ongoing because of Tregs' immunomodulatory function, ability to traffic to the CNS, high numbers correlating with slower disease in ALS and disease-modifying activity in ALS mouse models. In the current study, a chimeric antigen receptor (CAR) was developed and characterized in human Tregs to enhance their immunomodulatory activity when in contact with an ALS protein aggregate.

METHODS

A CAR (DG05-28-3z) consisting of a human superoxide dismutase 1 (hSOD1)-binding single-chain variable fragment, CD28 hinge, transmembrane and co-stimulatory domain and CD3ζ signaling domain was created and expressed in human Tregs. Human Tregs were isolated by either magnetic enrichment for CD4+CD25hi cells (Enr-Tregs) or cell sorting for CD4+CD25hiCD127lo cells (FP-Tregs), transduced and expanded for 17 days.

RESULTS

The CAR bound preferentially to the ALS mutant G93A-hSOD1 protein relative to the wild-type hSOD1 protein. The CAR Tregs produced IL-10 when cultured with aggregated G93A-hSOD1 proteins or spinal cord explants from G93A-hSOD1 transgenic mice. Co-culturing DG05-28-3z CAR Tregs with human monocytes/macrophages inhibited production of tumor necrosis factor alpha and reactive oxygen species. Expanded FP-Tregs resulted in more robust Tregs compared with Enr-Tregs. FP-Tregs produced similar IL-10 and less interferon gamma, had lower Treg-specific demethylated region methylation and expressed higher FoxP3 and CD39.

CONCLUSIONS

Taken together, this study demonstrates that gene-modified Tregs can be developed to target an aggregated ALS-relevant protein to elicit CAR-mediated Treg effector functions and provides an approach for generating Treg therapies for ALS with the goal of enhanced disease site-specific immunomodulation.

The Inflammatory Puzzle: Piecing together the Links between Neuroinflammation and Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that has a complex genetic basis. Through advancements in genetic screening, researchers have identified more than 40 mutant genes associated with ALS, some of which impact immune function. Neuroinflammation, with abnormal activation of immune cells and excessive production of inflammatory cytokines in the central nervous system, significantly contributes to the pathophysiology of ALS. In this review, we examine recent evidence on the involvement of ALS-associated mutant genes in immune dysregulation, with a specific focus on the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway and N6-methyladenosine (m6A)-mediated immune regulation in the context of neurodegeneration. We also discuss the perturbation of immune cell homeostasis in both the central nervous system and peripheral tissues in ALS. Furthermore, we explore the advancements made in the emerging genetic and cell-based therapies for ALS. This review underscores the complex relationship between ALS and neuroinflammation, highlighting the potential to identify modifiable factors for therapeutic intervention. A deeper understanding of the connection between neuroinflammation and the risk of ALS is crucial for advancing effective treatments for this debilitating disorder.

Impact of inflammation and Treg cell regulation on neuropathic pain in spinal cord injury: mechanisms and therapeutic prospects

Spinal cord injury is a severe neurological trauma that can frequently lead to neuropathic pain. During the initial stages following spinal cord injury, inflammation plays a critical role; however, excessive inflammation can exacerbate pain. Regulatory T cells (Treg cells) have a crucial function in regulating inflammation and alleviating neuropathic pain. Treg cells release suppressor cytokines and modulate the function of other immune cells to suppress the inflammatory response. Simultaneously, inflammation impedes Treg cell activity, further intensifying neuropathic pain. Therefore, suppressing the inflammatory response while enhancing Treg cell regulatory function may provide novel therapeutic avenues for treating neuropathic pain resulting from spinal cord injury. This review comprehensively describes the mechanisms underlying the inflammatory response and Treg cell regulation subsequent to spinal cord injury, with a specific focus on exploring the potential mechanisms through which Treg cells regulate neuropathic pain following spinal cord injury. The insights gained from this review aim to provide new concepts and a rationale for the therapeutic prospects and direction of cell therapy in spinal cord injury-related conditions.

Neuroinflammation and Neurodegenerative Diseases: How Much Do We Still Not Know?

The term "neuroinflammation" defines the typical inflammatory response of the brain closely related to the onset of many neurodegenerative diseases (NDs). Neuroinflammation is well known, but its mechanisms and pathways are not entirely comprehended. Some progresses have been achieved through many efforts and research. Consequently, new cellular and molecular mechanisms, diverse and conventional, are emerging. In listing some of those that will be the subject of our description and discussion, essential are the important roles of peripheral and infiltrated monocytes and clonotypic cells, alterations in the gut-brain axis, dysregulation of the apelinergic system, alterations in the endothelial glycocalyx of the endothelial component of neuronal vascular units, variations in expression of some genes and levels of the encoding molecules by the action of microRNAs (miRNAs), or other epigenetic factors and distinctive transcriptional factors, as well as the role of autophagy, ferroptosis, sex differences, and modifications in the circadian cycle. Such mechanisms can add significantly to understanding the complex etiological puzzle of neuroinflammation and ND. In addition, they could represent biomarkers and targets of ND, which is increasing in the elderly.

T cell biology in neuromuscular disorders: a focus on Duchenne Muscular Dystrophy and Amyotrophic Lateral Sclerosis

Growing evidence demonstrates a continuous interaction between the immune system, the nerve and the muscle in neuromuscular disorders of different pathogenetic origins, such as Duchenne Muscular Dystrophy (DMD) and Amyotrophic Lateral Sclerosis (ALS), the focus of this review. Herein we highlight the complexity of the cellular and molecular interactions involving the immune system in neuromuscular disorders, as exemplified by DMD and ALS. We describe the distinct types of cell-mediated interactions, such as cytokine/chemokine production as well as cell-matrix and cell-cell interactions between T lymphocytes and other immune cells, which target cells of the muscular or nervous tissues. Most of these interactions occur independently of exogenous pathogens, through ligand-receptor binding and subsequent signal transduction cascades, at distinct levels of specificity. Although this issue reveals the complexity of the system, it can also be envisioned as a window of opportunity to design therapeutic strategies (including synthetic moieties, cell and gene therapy, as well as immunotherapy) by acting upon one or more targets. In this respect, we discuss ongoing clinical trials using VLA-4 inhibition in DMD, and in ALS, with a focus on regulatory T cells, both revealing promising results.

Differential Effects of Regulatory T Cells in the Meninges and Spinal Cord of Male and Female Mice with Neuropathic Pain

Immune cells play a critical role in promoting neuroinflammation and the development of neuropathic pain. However, some subsets of immune cells are essential for pain resolution. Among them are regulatory T cells (Tregs), a specialised subpopulation of T cells that limit excessive immune responses and preserve immune homeostasis. In this study, we utilised intrathecal adoptive transfer of activated Tregs in male and female mice after peripheral nerve injury to investigate Treg migration and whether Treg-mediated suppression of pain behaviours is associated with changes in peripheral immune cell populations in lymphoid and meningeal tissues and spinal microglial and astrocyte reactivity and phenotypes. Treatment with Tregs suppressed mechanical pain hypersensitivity and improved changes in exploratory behaviours after chronic constriction injury (CCI) of the sciatic nerve in both male and female mice. The injected Treg cells were detected in the choroid plexus and the pia mater and in peripheral lymphoid organs in both male and female recipient mice. Nonetheless, Treg treatment resulted in differential changes in meningeal and lymph node immune cell profiles in male and female mice. Moreover, in male mice, adoptive transfer of Tregs ameliorated the CCI-induced increase in microglia reactivity and inflammatory phenotypic shift, increasing M2-like phenotypic markers and attenuating astrocyte reactivity and neurotoxic astrocytes. Contrastingly, in CCI female mice, Treg injection increased astrocyte reactivity and neuroprotective astrocytes. These findings show that the adoptive transfer of Tregs modulates meningeal and peripheral immunity, as well as spinal glial populations, and alleviates neuropathic pain, potentially through different mechanisms in males and females.

Regulatory T lymphocytes as a therapy for ischemic stroke

Unrestrained excessive inflammatory responses exacerbate ischemic brain injury and impede post-stroke brain recovery. CD4+CD25+Foxp3+ regulatory T (Treg) cells play important immunosuppressive roles to curtail inflammatory responses and regain immune homeostasis after stroke. Accumulating evidence confirms that Treg cells are neuroprotective at the acute stage after stroke and promote brain repair at the chronic phases. The beneficial effects of Treg cells are mediated by diverse mechanisms involving cell-cell interactions and soluble factor release. Multiple types of cells, including both immune cells and non-immune CNS cells, have been identified to be cellular targets of Treg cells. In this review, we summarize recent findings regarding the function of Treg cells in ischemic stroke and the underlying cellular and molecular mechanisms. The protective and reparative properties of Treg cells endorse them as good candidates for immune therapy. Strategies that boost the numbers and functions of Treg cells have been actively developing in the fields of transplantation and autoimmune diseases. We discuss the approaches for Treg cell expansion that have been tested in stroke models. The application of these approaches to stroke patients may bring new hope for stroke treatments.

ALSUntangled #65: glucocorticoid corticosteroids

ALSUntangled reviews alternative and off-label treatments for people with amyotrophic lateral sclerosis (PALS). Here we review glucocorticoids. Neuroinflammation plays a prominent role in amyotrophic lateral sclerosis (ALS) pathogenesis, so some hypothesize that glucocorticoids might be an effective ALS therapy through their immunosuppressive effects. In this paper, we review the available evidence for glucocorticoids in ALS, including one pre-clinical study with a genetic mouse model of ALS, nine case reports (ranging from 1 to 26 patients each), and four clinical trials. We also review the possible side effects (including steroid myopathy) and the costs of therapy. We graded the level of evidence as follows: Mechanism, D; Pre-Clinical, F; Cases, B; Trials, F; Risks, C. Our review of the current evidence concludes that glucocorticoids do not offer clinical benefit in ALS and confer serious risks. Thus, ALSUntangled does not recommend glucocorticoids as a treatment for ALS.

TREGking From Gut to Brain: The Control of Regulatory T Cells Along the Gut-Brain Axis

The human gastrointestinal tract has an enormous and diverse microbial community, termed microbiota, that is necessary for the development of the immune system and tissue homeostasis. In contrast, microbial dysbiosis is associated with various inflammatory and autoimmune diseases as well as neurological disorders in humans by affecting not only the immune system in the gastrointestinal tract but also other distal organs. FOXP3⁺ regulatory T cells (Tregs) are a subset of CD4⁺ helper T cell lineages that function as a gatekeeper for immune activation and are essential for peripheral autoimmunity prevention. Tregs are crucial to the maintenance of immunological homeostasis and tolerance at barrier regions. Tregs reside in both lymphoid and non-lymphoid tissues, and tissue-resident Tregs have unique tissue-specific phenotype and distinct function. The gut microbiota has an impact on Tregs development, accumulation, and function in periphery. Tregs, in turn, modulate antigen-specific responses aimed towards gut microbes, which supports the host–microbiota symbiotic interaction in the gut. Recent studies have indicated that Tregs interact with a variety of resident cells in central nervous system (CNS) to limit the progression of neurological illnesses such as ischemic stroke, Alzheimer’s disease, and Parkinson’s disease. The gastrointestinal tract and CNS are functionally connected, and current findings provide insights that Tregs function along the gut-brain axis by interacting with immune, epithelial, and neuronal cells. The purpose of this study is to explain our current knowledge of the biological role of tissue-resident Tregs, as well as the interaction along the gut-brain axis.

A phase I/IIa clinical trial of autologous hematopoietic stem cell transplantation in amyotrophic lateral sclerosis

OBJECTIVE

To verify the safety and potential effect on ALS progression of a low-intensity immunosuppressive regimen followed by autologous hematopoietic stem cell transplantation (aHSCT) in amyotrophic lateral sclerosis (ALS) patients.

METHODS

ALS eligible patients underwent a set of clinical and laboratory evaluations at T-4 (screening), T-1 (pre-treatment visit), and for the 12 consecutive months after treatment (T3, T6, T9, T12). We evaluated the tolerability of the procedure, its efficacy on clinical course and quality of life (QoL).

RESULTS

Eight of the 11 ALS patients enrolled received the established immunoablative protocol. The procedure was well tolerated and side effects were those expected. One patient died 4 months after the conditioning regimen and another patient underwent tracheotomy just before T3 for a sudden respiratory failure, but he is still alive 4 years after the procedure without being ventilated any more. A third patient died 10 months after conditioning. In the other cases, there was no statistical difference in all functional measures and QoL pre- and post-treatment; however, a transitory slopes' reduction of ALSFRS-R and seated SVC% after the conditioning procedures was reported. Moreover, although not statistically significant, trends of reduction of CD4 + and increment of CD8 + were found.

CONCLUSIONS

aHSCT was overall well tolerated, but it was not followed by any significant modification in disease progression. Considering the negative results of this small trial, further studies aimed to evaluate the possible efficacy of the aHSCT using a higher-intensity regimen should be carefully and with caution evaluated.

Neuroimmune Crosstalk Between the Peripheral and the Central Immune System in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by the degeneration and death of motor neurons. Systemic neuroinflammation contributes to the pathogenesis of ALS. The proinflammatory milieu depends on the continuous crosstalk between the peripheral immune system (PIS) and central immune system (CIS). Central nervous system (CNS) resident immune cells interact with the peripheral immune cells via immune substances. Dysfunctional CNS barriers, including the blood–brain barrier, and blood–spinal cord barrier, accelerate the inflammatory process, leading to a systemic self-destructive cycle. This review focuses on the crosstalk between PIS and CIS in ALS. Firstly, we briefly introduce the cellular compartments of CIS and PIS, respectively, and update some new understanding of changes specifically occurring in ALS. Then, we will review previous studies on the alterations of the CNS barriers, and discuss their crucial role in the crosstalk in ALS. Finally, we will review the moveable compartments of the crosstalk, including cytokines, chemokines, and peripheral immune cells which were found to infiltrate the CNS, highlighting the interaction between PIS and CIS. This review aims to provide new insights into pathogenic mechanisms and innovative therapeutic approaches for ALS.

Biomarker discovery and development for frontotemporal dementia and amyotrophic lateral sclerosis

Frontotemporal dementia refers to a group of neurodegenerative disorders characterized by behaviour and language alterations and focal brain atrophy. Amyotrophic lateral sclerosis is a rapidly progressing neurodegenerative disease characterized by loss of motor neurons resulting in muscle wasting and paralysis. Frontotemporal dementia and amyotrophic lateral sclerosis are considered to exist on a disease spectrum given substantial overlap of genetic and molecular signatures. The predominant genetic abnormality in both frontotemporal dementia and amyotrophic lateral sclerosis is an expanded hexanucleotide repeat sequence in the C9orf72 gene. In terms of brain pathology, abnormal aggregates of TAR-DNA-binding protein-43 are predominantly present in frontotemporal dementia and amyotrophic lateral sclerosis patients. Currently, sensitive and specific diagnostic and disease surveillance biomarkers are lacking for both diseases. This has impeded the capacity to monitor disease progression during life and the development of targeted drug therapies for the two diseases. The purpose of this review is to examine the status of current biofluid biomarker discovery and development in frontotemporal dementia and amyotrophic lateral sclerosis. The major pathogenic proteins implicated in different frontotemporal dementia and amyotrophic lateral sclerosis molecular subtypes and proteins associated with neurodegeneration and the immune system will be discussed. Furthermore, the use of mass spectrometry-based proteomics as an emerging tool to identify new biomarkers in frontotemporal dementia and amyotrophic lateral sclerosis will be summarized.

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.

Amyotrophic lateral sclerosis transcriptomics reveals immunological effects of low-dose interleukin-2

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease causing upper and lower motor neuron loss and currently no effective disease-modifying treatment is available. A pathological feature of this disease is neuroinflammation, a mechanism which involves both CNS-resident and peripheral immune system cells. Regulatory T-cells are immune-suppressive agents known to be dramatically and progressively decreased in patients with amyotrophic lateral sclerosis. Low-dose interleukin-2 promotes regulatory T-cell expansion and was proposed as an immune-modulatory strategy for this disease. A randomized placebo-controlled pilot phase-II clinical trial called Immuno-Modulation in Amyotrophic Lateral Sclerosis was carried out to test safety and activity of low-dose interleukin-2 in 36 amyotrophic lateral sclerosis patients (NCT02059759). Participants were randomized to 1MIU, 2MIU-low-dose interleukin-2 or placebo and underwent one injection daily for 5 days every 28 days for three cycles. In this report, we describe the results of microarray gene expression profiling of trial participants' leukocyte population. We identified a dose-dependent increase in regulatory T-cell markers at the end of the treatment period. Longitudinal analysis revealed an alteration and inhibition of inflammatory pathways occurring promptly at the end of the first treatment cycle. These responses are less pronounced following the end of the third treatment cycle, although an activation of immune-regulatory pathways, involving regulatory T-cells and T helper 2 cells, was evident only after the last cycle. This indicates a cumulative effect of repeated low-dose interleukin-2 administration on regulatory T-cells. Our analysis suggested the existence of inter-individual variation amongst trial participants and we therefore classified patients into low, moderate and high-regulatory T-cell-responders. NanoString profiling revealed substantial baseline differences between participant immunological transcript expression profiles with the least responsive patients showing a more inflammatory-prone phenotype at the beginning of the trial. Finally, we identified two genes in which pre-treatment expression levels correlated with the magnitude of drug responsiveness. Therefore, we proposed a two-biomarker based regression model able to predict patient regulatory T-cell-response to low-dose interleukin-2. These findings and the application of this methodology could be particularly relevant for future precision medicine approaches to treat amyotrophic lateral sclerosis.

Evaluation of Peripheral Immune Activation in Amyotrophic Lateral Sclerosis

Accumulating evidence has revealed that immunity plays an important role in amyotrophic lateral sclerosis (ALS) progression. However, the results regarding the serum levels of immunoglobulin and complement are inconsistent in patients with ALS. Although immune dysfunctions have also been reported in patients with other neurodegenerative diseases, few studies have explored whether immune dysfunction in ALS is similar to that in other neurodegenerative diseases. Therefore, we performed this study to address these gaps. In the present study, serum levels of immunoglobulin and complement were measured in 245 patients with ALS, 65 patients with multiple system atrophy (MSA), 60 patients with Parkinson's disease (PD), and 82 healthy controls (HCs). Multiple comparisons revealed that no significant differences existed between patients with ALS and other neurodegenerative diseases in immunoglobulin and complement levels. Meta-analysis based on data from our cohort and eight published articles was performed to evaluate the serum immunoglobulin and complement between patients with ALS and HCs. The pooled results showed that patients with ALS had higher C4 levels than HCs. In addition, we found that the IgG levels were lower in early-onset ALS patients than in late-onset ALS patients and HCs, and the correlations between age at onset of ALS and IgG or IgA levels were significant positive. In conclusion, our data supplement existing literature on understanding the role of peripheral immunity in ALS.

NOX2 Activation in COVID-19: Possible Implications for Neurodegenerative Diseases

Coronavirus disease 2019 (COVID-19) is a rapidly spreading contagious infectious disease caused by the pathogen severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that primarily affects the respiratory tract as well as the central nervous system (CNS). SARS-CoV-2 infection occurs through the interaction of the viral protein Spike with the angiotensin II receptor (ACE 2), leading to an increase of angiotensin II and activation of nicotinamide adenine dinucleotide phosphate oxidase2 (NOX2), resulting in the release of both reactive oxygen species (ROS) and inflammatory molecules. The purpose of the review is to explain that SARS-CoV-2 infection can determine neuroinflammation that induces NOX2 activation in microglia. To better understand the role of NOX2 in inflammation, an overview of its involvement in neurodegenerative diseases (NDs) such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and amyotrophic lateral sclerosis (ALS) is provided. To write this manuscript, we performed a PubMed search to evaluate the possible relationship of SARS-CoV-2 infection in NOX2 activation in microglia, as well as the role of NOX2 in NDs. Several studies highlighted that NOX2 activation in microglia amplifies neuroinflammation. To date, there is no clinical treatment capable of counteracting its activation, however, NOX2 could be a promising pharmaceutical target useful for both the treatment and prevention of NDs and COVID-19 treatment.

Immune Response in Neurological Pathology: Emerging Role of Central and Peripheral Immune Crosstalk

Neuroinflammation is a key component of neurological disorders and is an important therapeutic target; however, immunotherapies have been largely unsuccessful. In cases where these therapies have succeeded, particularly multiple sclerosis, they have primarily focused on one aspect of the disease and leave room for improvement. More recently, the impact of the peripheral immune system is being recognized, since it has become evident that the central nervous system is not immune-privileged, as once thought. In this review, we highlight key interactions between central and peripheral immune cells in neurological disorders. While traditional approaches have examined these systems separately, the immune responses and processes in neurological disorders consist of substantial crosstalk between cells of the central and peripheral immune systems. Here, we provide an overview of major immune effector cells and the role of the blood-brain barrier in regard to neurological disorders and provide examples of this crosstalk in various disorders, including stroke and traumatic brain injury, multiple sclerosis, neurodegenerative diseases, and brain cancer. Finally, we propose targeting central-peripheral immune interactions as a potential improved therapeutic strategy to overcome failures in clinical translation.

Non-neuronal cells in amyotrophic lateral sclerosis - from pathogenesis to biomarkers

The prevailing motor neuron-centric view of amyotrophic lateral sclerosis (ALS) pathogenesis could be an important factor in the failure to identify disease-modifying therapy for this neurodegenerative disorder. Non-neuronal cells have crucial homeostatic functions within the CNS and evidence of involvement of these cells in the pathophysiology of several neurodegenerative disorders, including ALS, is accumulating. Microglia and astrocytes, in crosstalk with peripheral immune cells, can exert both neuroprotective and adverse effects, resulting in a highly nuanced range of neuronal and non-neuronal cell interactions. This Review provides an overview of the diverse roles of non-neuronal cells in relation to the pathogenesis of ALS and the emerging potential of non-neuronal cell biomarkers to advance therapeutic development.

Treg cell-derived osteopontin promotes microglia-mediated white matter repair after ischemic stroke

The precise mechanisms underlying the beneficial effects of regulatory T (Treg) cells on long-term tissue repair remain elusive. Here, using single-cell RNA sequencing and flow cytometry, we found that Treg cells infiltrated the brain 1 to 5 weeks after experimental stroke in mice. Selective depletion of Treg cells diminished oligodendrogenesis, white matter repair, and functional recovery after stroke. Transcriptomic analyses revealed potent immunomodulatory effects of brain-infiltrating Treg cells on other immune cells, including monocyte-lineage cells. Microglia depletion, but not T cell lymphopenia, mitigated the beneficial effects of transferred Treg cells on white matter regeneration. Mechanistically, Treg cell-derived osteopontin acted through integrin receptors on microglia to enhance microglial reparative activity, consequently promoting oligodendrogenesis and white matter repair. Increasing Treg cell numbers by delivering IL-2:IL-2 antibody complexes after stroke improved white matter integrity and rescued neurological functions over the long term. These findings reveal Treg cells as a neurorestorative target for stroke recovery.

Modification of Glial Cell Activation through Dendritic Cell Vaccination: Promises for Treatment of Neurodegenerative Diseases

Accumulation of misfolded tau, amyloid β (Aβ), and alpha-synuclein (α-syn) proteins is the fundamental contributor to many neurodegenerative diseases, namely Parkinson's (PD) and AD. Such protein aggregations trigger activation of immune mechanisms in neuronal and glial, mainly M1-type microglia cells, leading to release of pro-inflammatory mediators, and subsequent neuronal dysfunction and apoptosis. Despite the described neurotoxic features for glial cells, recruitment of peripheral leukocytes to the brain and their conversion to neuroprotective M2-type microglia can mitigate neurodegeneration by clearing extracellular protein accumulations or residues. Based on these observations, it was speculated that Dendritic cell (DC)-based vaccination, by making use of DCs as natural adjuvants, could be used for treatment of neurodegenerative disorders. DCs potentiated by disease-specific antigens can also enhance T helper 2 (Th2)-specific immune response and by production of specific antibodies contribute to clearance of intracellular aggregations, as well as enhancing regulatory T cell response. Thus, enhancement of immune response by DC vaccine therapy can potentially augment glial polarization into the neuroprotective phenotype, enhance antibody production, and at the same time balance neuronal cells' repair, renewal, and protection. The characteristic feature of this method of treatment is to maintain the equilibrium in the immune response rather than targeting a single mediator in the disease and their application in other neurodegenerative diseases should be addressed. However, the safety of these methods should be investigated by clinical trials.

Oxidative Stress, Neuroinflammation and Mitochondria in the Pathophysiology of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron (MN) disease. Its primary cause remains elusive, although a combination of different causal factors cannot be ruled out. There is no cure, and prognosis is poor. Most patients with ALS die due to disease-related complications, such as respiratory failure, within three years of diagnosis. While the underlying mechanisms are unclear, different cell types (microglia, astrocytes, macrophages and T cell subsets) appear to play key roles in the pathophysiology of the disease. Neuroinflammation and oxidative stress pave the way leading to neurodegeneration and MN death. ALS-associated mitochondrial dysfunction occurs at different levels, and these organelles are involved in the mechanism of MN death. Molecular and cellular interactions are presented here as a sequential cascade of events. Based on our present knowledge, the discussion leads to the idea that feasible therapeutic strategies should focus in interfering with the pathophysiology of the disease at different steps.

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.

Peripheral and Central Nervous System Immune Response Crosstalk in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by muscle weakness due to the degeneration of the upper and lower motor neurons. Neuroinflammation is known as a prominent pathological feature of ALS. Although neuroinflammation cannot trigger ALS, activated central nervous system (CNS) microglia and astrocytes, proinflammatory periphery monocytes/macrophages and T lymphocytes, and infiltrated monocytes/macrophages and T lymphocytes, as well as the immunoreactive molecules they release, are closely related to disease progression. The crosstalk between the peripheral and CNS immune components mentioned above significantly correlates with survival in patients with ALS. This review provides an update on the role of this crosstalk between the CNS and peripheral immune responses in ALS. Additionally, we discuss changes in the composition of gut microbiota because these can directly or indirectly influence this crosstalk. These recent advances may well provide innovative ways for targeting the molecules associated with this crosstalk and breaking the current treatment impasse in ALS.

Harnessing regulatory T cell neuroprotective activities for treatment of neurodegenerative disorders

Emerging evidence demonstrates that adaptive immunity influences the pathobiology of neurodegenerative disorders. Misfolded aggregated self-proteins can break immune tolerance leading to the induction of autoreactive effector T cells (Teffs) with associated decreases in anti-inflammatory neuroprotective regulatory T cells (Tregs). An imbalance between Teffs and Tregs leads to microglial activation, inflammation and neuronal injury. The cascade of such a disordered immunity includes the drainage of the aggregated protein antigens into cervical lymph nodes serving to amplify effector immune responses. Both preclinical and clinical studies demonstrate transformation of this altered immunity for therapeutic gain. We posit that the signs and symptoms of common neurodegenerative disorders such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, and stroke can be attenuated by boosting Treg activities.

The involvement of regulatory T cells in amyotrophic lateral sclerosis and their therapeutic potential

Neuroinflammation, meaning the establishment of a diffuse inflammatory condition in the CNS, is one of the main hallmarks of amyotrophic lateral sclerosis (ALS). Recently, a crucial role of regulatory T cells (Tregs) in this disease has been outlined. Tregs are a T cell subpopulation with immunomodulatory properties. In this review, we discuss the physiology of Tregs and their role in ALS disease onset and progression. Evidence has demonstrated that in ALS patients Tregs are dramatically and progressively reduced in number and are less effective in promoting immune suppression. In addition, Tregs levels correlate with the rate of disease progression and patient survival. For this reason, Tregs are now considered a promising therapeutic target for neuroprotection in ALS. In this review, the clinical impact of these cells will be discussed and an overview of the current clinical trials targeting Tregs is also provided.

Immunosuppressive Functions of M2 Macrophages Derived from iPSCs of Patients with ALS and Healthy Controls

Amyotrophic lateral sclerosis (ALS) is a disorder with immune alterations that augment disease severity. M2 macrophages benefit diabetic and nephrotic mice by suppressing the pro-inflammatory state. However, neither have M2 cells been investigated in ALS nor have human induced pluripotent stem cell (iPSC)-derived M2 cells been thoroughly studied for immunosuppressive potentials. Here, iPSCs of C9orf72 mutated or sporadic ALS patients were differentiated into M2 macrophages, which suppressed activation of pro-inflammatory M1 macrophages as well as proliferation of ALS CD4⁺CD25^- Tc (Teffs). M2 cells converted ALS Teffs into CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) and rescued Tregs of ALS patients from losing CD25 and Foxp3. Furthermore, Tregs induced or rescued by iPSC-derived M2 had strong suppressive functions. ALS iPSC-derived M2 cells including those with C9orf72 mutation had similar immunomodulatory activity as control iPSC-derived M2 cells. This study demonstrates that M2 cells differentiated from iPSCs of ALS patients are immunosuppressive, boost ALS Tregs, and may serve as a candidate for immune-cell-based therapy to mitigate inflammation in ALS.

Natural killer cells modulate motor neuron-immune cell cross talk in models of Amyotrophic Lateral Sclerosis

In amyotrophic lateral sclerosis (ALS), immune cells and glia contribute to motor neuron (MN) degeneration. We report the presence of NK cells in post-mortem ALS motor cortex and spinal cord tissues, and the expression of NKG2D ligands on MNs. Using a mouse model of familial-ALS, hSOD1^G93A, we demonstrate NK cell accumulation in the motor cortex and spinal cord, with an early CCL2-dependent peak. NK cell depletion reduces the pace of MN degeneration, delays motor impairment and increases survival. This is confirmed in another ALS mouse model, TDP43^A315T. NK cells are neurotoxic to hSOD1^G93A MNs which express NKG2D ligands, while IFNγ produced by NK cells instructs microglia toward an inflammatory phenotype, and impairs FOXP3⁺/Treg cell infiltration in the spinal cord of hSOD1^G93A mice. Together, these data suggest a role of NK cells in determining the onset and progression of MN degeneration in ALS, and in modulating Treg recruitment and microglia phenotype.

Neuroimmune interactions are important in amyotrophic lateral sclerosis (ALS). Here the authors characterize the role of NK cells in mouse models of ALS, and in patient tissue.

Mild Cognitive Impairment Patients Have Higher Regulatory T-Cell Proportions Compared With Alzheimer's Disease-Related Dementia Patients

Objectives: The role of neuroinflammation in the pathogenesis of Alzheimer's disease (AD) has attracted much attention recently. Regulatory T-cells (Tregs) play an important role in modulating inflammation. We aimed to explore the Treg-related immunosuppression status at different stages of AD. Methods: Thirty healthy control (HC) subjects, 26 patients with mild cognitive impairment (MCI), 30 patients with mild probable AD-related dementia, and 28 patients with moderate-to-severe probable AD-related dementia underwent detailed clinical history taking, structural MRI scanning, and neuropsychological assessment. Peripheral blood samples were taken to measure the percentage of CD4⁺CD25⁺CD127^low/- Tregs by flow cytometry and the levels of interleukin (IL-10), interleukin (IL-35), and transforming growth factor β (TGF-β) by ELISA. Results: The percentage of Tregs in the blood of MCI patients was the highest (9.24%); there was a significant difference between patients with MCI and patients with probable AD-related dementia. The level of TGF-β in patients with MCI (47.02 ng/ml) was significantly increased compared with patients with AD-related dementia. There were positive correlations between Treg percentage, IL-35, and Mini-mental state evaluation scores in patients with MCI and probable AD-related dementia. Conclusions: Patients with MCI have stronger Treg-related immunosuppression status compared with patients with probable AD-related dementia.

Regulatory T cells for amyotrophic lateral sclerosis/motor neuron disease: A clinical and preclinical systematic review

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by neuronal degeneration and inflammation in the nerves. The role of the immune system has been concentrated by researchers in the etiopathogenesis of the disease. Given the inhibitory roles of regulatory T cells (Tregs), it is expected that increasing or activating their populations in patients with ALS can have significant therapeutic effects. Here we searched databases, including CENTRAL, MEDLINE, CINAHL Plus, clinicaltrials.gov, and ICTRP for randomized clinical trials (RCTs) and non-RCTs until March 2019. For preclinical studies, we searched PubMed, Scopus, and Google Scholar up to June 2019. We also included preclinical studies, due to the lack of clinical information available, which used Tregs (or directly targeting them) for treating mice models of ALS. We identified 29 records (CENTRAL 7, MEDLINE 4, CINAHL Plus 8, and clinicaltrials.gov 10) and removed 10 duplicated publications. After screening, we identified one RCT which had been published as an abstract, three non-RCTs, and four ongoing studies. We also identified 551 records (PubMed 446, Google Scholar 68, and Scopus 37) for preclinical studies and performed a meta-analysis. Finally, we found three papers that matched our inclusion criteria for preclinical studies. Results indicated the effectiveness of the application of Tregs in the treatment of ALS. Our meta-analysis on preclinical studies revealed that Tregs significantly prolonged survival in mice models of ALS. Overall, our analysis testified that exertion of Tregs in the treatment of ALS is a promising approach, that notwithstanding, requires further evaluations.

Inflammation in ALS/FTD pathogenesis

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases that overlap in their clinical presentation, pathology and genetics, and likely represent a spectrum of one underlying disease. In ALS/FTD patients, neuroinflammation characterized by innate immune responses of tissue-resident glial cells is uniformly present on end-stage pathology, and human imaging studies and rodent models support that neuroinflammation begins early in disease pathogenesis. Additionally, changes in circulating immune cell populations and cytokines are found in ALS/FTD patients, and there is evidence for an autoinflammatory state. However, despite the prominent role of neuro- and systemic inflammation in ALS/FTD, and experimental evidence in rodents that altering microglial function can mitigate pathology, therapeutic approaches to decrease inflammation have thus far failed to alter disease course in humans. Here, we review the characteristics of inflammation in ALS/FTD in both the nervous and peripheral immune systems. We further discuss evidence for direct influence on immune cell function by mutations in ALS/FTD genes including C9orf72, TBK1 and OPTN, and how this could lead to the altered innate immune system “tone” observed in these patients.

Neuroinflammatory mechanisms in amyotrophic lateral sclerosis pathogenesis

PURPOSE OF REVIEW

Neuroinflammation is increasingly recognized as an important mediator of disease progression in patients with amyotrophic lateral sclerosis (ALS), and is characterized by reactive central nervous system (CNS) microglia and astroglia as well as infiltrating peripheral monocytes and lymphocytes. Anti-inflammatory and neuroprotective factors sustain the early phase of the disease whereas inflammation becomes proinflammatory and neurotoxic as disease progression accelerates. Initially, motor neurons sustain injuries through multiple mechanisms resulting from harmful mutations causing disruptions of critical intracellular pathways. Injured motor neurons release distress signal(s), which induce inflammatory processes produced by surrounding glial cells in the CNS as well as peripheral innate and adaptive immune cells. This review will focus on mechanisms of neuroinflammation and their essential contributions in ALS pathogenesis.

RECENT FINDINGS

Regulatory T lymphocytes (Tregs) are a subpopulation of immunosuppressive T lymphocytes that become reduced and dysfunctional as the disease progresses in ALS patients. Their degree of dysfunction correlates with the extent and rapidity of the disease. Treg numbers are boosted in transgenic mutant SOD1 (mSOD1) mice through the passive transfer of Tregs or through treatment with an interleukin-2/ interleukin-2 monoclonal antibody complex and rapamycin. Treating the transgenic mice with either of these modalities delays disease progression and prolongs survival. In addition, Treg function is restored when dysfunctional Tregs are isolated from ALS patients and expanded ex vivo in the presence of interleukin-2 and rapamycin. Based on these findings, a first-in-human phase 1 trial has been completed in which expanded autologous Tregs were infused back into ALS patients as a potential treatment. The infusions were safe and shown to 'hit target' by enhancing both Treg numbers and suppressive functions.

SUMMARY

A delicate balance between anti-inflammatory and proinflammatory factors modulates the rates of disease progression and survival times in ALS. Tipping the balance toward the anti-inflammatory mediators shows promise in slowing the progression of this devastating disease.

Mesenchymal Stem Cells: A Potential Therapeutic Approach for Amyotrophic Lateral Sclerosis?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the degeneration of both upper and lower motor neurons. Patients show both motor and extra-motor symptoms. A cure is not available at this time, and the disease leads to death within 3-5 years, mainly due to respiratory failure. Stem cell therapy is arising as a new promising approach for the treatment of neurodegenerative disorders. In particular, mesenchymal stem cells (MSCs) seem the most suitable type of stem cells, thanks to their demonstrated beneficial effects in different experimental models, to the easy availability, and to the lack of ethical problems. In this review, we focused on the studies involving ALS rodent models and clinical trials in order to understand the potential beneficial effects of MSC transplantation. In different ALS rodent models, the administration of MSCs induced a delay in disease progression and at least a partial recovery of the motor function. In addition, clinical trials evidenced the feasibility and safety of MSC transplantation in ALS patients, given that no major adverse events were recorded. However, only partial improvements were shown. For this reason, more studies and trials are needed to clarify the real effectiveness of MSC-based therapy in ALS.

Attenuation of ALS progression during pregnancy-lessons to be learned or just a coincidence?

ALS is the most frequent motor neuron disorder in adults with suggested complex relationship regarding gender. Studies investigating ALS and hormones have provided varying results. ALS onset during pregnancy is uncommon and pregnancy after the ALS symptom onset is even rarer. We present three patients with the onset of ALS symptoms before or during pregnancy and propose a putative disease modifying mechanism leading to attenuation of disease progression that we observed during the pregnancies.

A pilot trial of RNS60 in amyotrophic lateral sclerosis

INTRODUCTION

RNS60 is a novel immune-modulatory agent that has shown neuroprotective effects in amytrophic lateral sclerosis (ALS) preclinical models. RNS60 is administered by weekly intravenous infusion and daily nebulization. The objective of this pilot open-label trial was to test the feasibility, safety, and tolerability of long-term RNS60 administration in ALS patients.

METHODS

The planned treatment duration was 23 weeks and the primary outcomes were safety and tolerability. Secondary outcomes included PBR28 positron emission tomography (PET) imaging and plasma biomarkers of inflammation.

RESULTS

Sixteen participants with ALS received RNS60 and 13 (81%) completed 23 weeks of RNS60 treatment. There were no serious adverse events and no participants withdrew from the trial due to drug-related adverse events. There were no significant changes in the biomarkers.

DISCUSSION

Long-term RNS60 administration was safe and well-tolerated. A large, multicenter, phase II trial of RNS60 is currently enrolling participants to test the effects of RNS60 on ALS biomarkers and disease progression. Muscle Nerve 59:303-308, 2019.

In Vivo Expansion of Regulatory T Cells with IL-2/IL-2 Antibody Complex Protects against Transient Ischemic Stroke

Regulatory T cells (Tregs) are known to protect against ischemic stroke. However, the low frequency of Tregs restricts their clinical utility. This study investigated whether expanding the number of Tregs in vivo with the IL-2/IL-2 antibody complex (IL-2/IL-2Ab) could improve stroke outcomes and further elaborated the mechanisms of protection in male mice. C57BL/6 mice received IL-2/IL-2Ab or isotype IgG (IsoAb) intraperitoneally for 3 d before (pretreatment) or starting 2 h after (posttreatment) 60 min middle cerebral artery occlusion (MCAO). IL-2/IL-2Ab selectively increased the number of Tregs in the blood, spleen, and lymph nodes. The IL-2/IL-2Ab treatment significantly reduced infarct volume, inhibited neuroinflammation, and improved sensorimotor functions, as manifested by rotarod test and foot fault test, compared with IsoAb-treated stroke mice. Treg depletion was then achieved by diphtheria toxin (DT) injection into transgenic mice expressing the DT receptor under the control of the Foxp3 promoter (DTR mice). The depletion of Tregs completely eliminated IL-2/IL-2Ab-afforded neuroprotection. Interestingly, adoptive transfer of Tregs collected from IL-2/IL-2Ab-treated mice demonstrated more potent neuroprotection than an equal number of Tregs prepared from IsoAb-treated mice, suggesting that IL-2/IL-2Ab not only elevated Treg numbers, but also boosted their functions. Mechanistically, IL-2/IL-2Ab promoted the expression of CD39 and CD73 in expanded Tregs. CD73 deficiency diminished the protective effect of IL-2/IL-2Ab-stimulated Tregs in stroke mice. The results show that IL-2/IL-2Ab expands Tregs in vivo and boosts their immunomodulatory function. The activation of CD39/CD73 signaling in Tregs may participate as a potential mechanism underlying IL-2/IL-2Ab-afforded neuroprotection against ischemic brain injury.SIGNIFICANCE STATEMENT Regulatory T cells (Tregs) are known to protect against ischemic stroke. However, the low frequency of Tregs restricts their clinical utility. This study reported that systemic administration of the IL-2/IL-2 antibody complex (IL-2/IL-2Ab) robustly and selectively expanded the number of Tregs after stroke. IL-2/IL-2Ab pretreatment or posttreatment significantly improved stroke outcomes in a rodent model of ischemic stroke. We further discovered that IL-2/IL-2Ab not only elevated Treg numbers, but also boosted their functions and enhanced the expression of CD39 and CD73. Using CD73-deficient mice, we confirmed the importance of CD73 in the protective effect of IL-2/IL-2Ab-stimulated Tregs in stroke mice. These results shed light on IL-2/IL-2Ab as a clinically feasible immune therapy to boost endogenous Treg responses and ameliorate ischemic brain injury.

Promises and limitations of immune cell-based therapies in neurological disorders

The healthy immune system has natural checkpoints that temper pernicious inflammation. Cells mediating these checkpoints include regulatory T cells, regulatory B cells, regulatory dendritic cells, microglia, macrophages and monocytes. Here, we highlight discoveries on the beneficial functions of regulatory immune cells and their mechanisms of action and evaluate their potential use as novel cell-based therapies for brain disorders. Regulatory immune cell therapies have the potential not only to mitigate the exacerbation of brain injury by inflammation but also to promote an active post-injury brain repair programme. By harnessing the reparative properties of these cells, we can reduce over-reliance on medications that mask clinical symptoms but fail to impede or reverse the progression of brain disorders. Although these discoveries encourage further testing and genetic engineering of regulatory immune cells for the clinical management of neurological disorders, a number of challenges must be surmounted to improve their safety and efficacy in humans.

Protective effects of Withania somnifera extract in SOD1G93A mouse model of amyotrophic lateral sclerosis

Withania somnifera (WS; commonly known as Ashwagandha or Indian ginseng) is a medicinal plant whose extracts have been in use for centuries in various regions of the world as a rejuvenator. There is now a growing body of evidence documenting neuroprotective functions of the plant extracts or its purified compounds in several models of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Based on the extract's beneficial effect in a mouse model of ALS with TDP-43 proteinopathy, the current study was designed to test its efficacy in another model of familial ALS. Our results show that administration of WS extracts by gavage to mice expressing G93A mutant form of superoxide dismutase (SOD1) resulted in increased longevity, improved motor performance and increased number of motor neurons in lumbar spinal cord. The WS treatment caused substantial reduction in levels of misfolded SOD1whereas it enhanced expression of cellular chaperons in spinal cord of SOD1^G93A mice. WS markedly reduced glial activation and prevented phosphorylation of nuclear factor kappaB (NF-κB). The overall immunomodulatory effect of WS was further evidenced by changes in expression of multiple cytokines/chemokines. WS also served as an autophagy inducer which may be beneficial at early stages of the disease. These results suggest that WS extracts might constitute promising therapeutics for treatment of ALS with involvement of misfolded SOD1.

Neuroinflammation in Amyotrophic Lateral Sclerosis: Role of Redox (dys)Regulation

SIGNIFICANCE

Amyotrophic lateral sclerosis (ALS) is due to degeneration of upper and lower motor neurons in the anterior horn of the spinal cord and in the motor cortex. Mechanisms leading to motor neuron death are complex and currently the disease is untreatable. Recent Advances: Work in genetic models of ALS indicates that an imbalance in the cross talk that physiologically exists between motor neurons and the surrounding cells is eventually detrimental to motor neurons. In particular, the cascade of events collectively known as neuroinflammation and mainly characterized by a reactive phenotype of astrocytes and microglia, moderate infiltration of peripheral immune cells, and elevated levels of inflammatory mediators has been consistently observed in motor regions of the central nervous system (CNS) in sporadic and familial ALS, constituting a hallmark of the disease. Resident glial cells and infiltrated immune cells are considered among the major producers of reactive species of oxygen and nitrogen in pathological conditions of the CNS, including motor neuron diseases.

CRITICAL ISSUES

The timing and exact role of oxidative stress-mediated neuroinflammation and damage to motor neurons in ALS are still not fully elucidated.

FUTURE DIRECTIONS

It is clear that a major challenge in the next future will be to envisage effective strategies to modulate the neuroinflammatory response in the symptomatic stage of disease, to prevent progression of neurodegeneration through the propagation of oxidative damage. Antioxid. Redox Signal. 29, 15-36.

Expanded autologous regulatory T-lymphocyte infusions in ALS: A phase I, first-in-human study

Objective

To determine whether autologous infusions of expanded regulatory T lymphoctyes (Tregs) into patients with amyotrophic lateral sclerosis (ALS) are safe and tolerable during early and later stages of disease.

Methods

Three patients with ALS, with no family history of ALS, were selected based on their differing sites of disease onset and rates of progression. Patients underwent leukapheresis, and Tregs were subsequently isolated and expanded ex vivo. Tregs (1 × 10⁶ cells/kg) were administered IV at early stages (4 doses over 2 months) and later stages (4 doses over 4 months) of disease. Concomitant interleukin-2 (2 × 10⁵ IU/m²/injection) was administered subcutaneously 3 times weekly over the entire study period. Patients were closely monitored for adverse effects and changes in disease progression rates. Treg numbers and suppressive function were assayed during and following each round of Treg infusions.

Results

Infusions of Tregs were safe and well tolerated in all patients. Treg numbers and suppressive function increased after each infusion. The infusions slowed progression rates during early and later stages of disease. Spearman correlation analyses showed that increased Treg suppressive function correlated with slowing of disease progression per the Appel ALS scale for each patient: patient 1: ρ (rho) = −0.60, p = 0.003; patient 2: ρ = −0.71, p = 0.0026; and patient 3: ρ = −0.54, p = 0.016. Measures of maximal inspiratory pressure also stabilized, particularly in 2 patients, during Treg infusions.

Conclusions

These results demonstrate the safety and potential benefit of expanded autologous Treg infusions, warranting further clinical trials in patients with ALS. The correlation between Treg suppressive function and disease progression underscores the significance of using Treg suppressive function as an indicator of clinical status.

Classification of evidence

This study provides Class IV evidence. This is a phase I trial with no controls.

Friend or foe: the dichotomous impact of T cells on neuro-de/re-generation during aging

The interaction between T cells and the central nervous system (CNS) in homeostasis and injury has been recognized being both pathogenic (CD4⁺ T-helper 1 - Th1, Th17 and γδT) and ameliorative (Th2 and regulatory T cells - Tregs). However, in-depth studies aimed to elucidate the precise in the aged microenvironment and the dichotomous role of Tregs have just begun and many aspects remain unclear. This is due, not only to a mutual dependency and reciprocal causation of alterations and diseases between the nervous and T cell immune systems, but also to an inconsistent aging of the two systems, which dynamically changes with CNS injury/recovery and/or aging process. Cellular immune system aging, particularly immunosenescence and T cell aging initiated by thymic involution - sources of chronic inflammation in the elderly (termed inflammaging), potentially induces an acceleration of brain aging and memory loss. In turn, aging of the brain via neuro-endocrine-immune network drives total body systemic aging, including that of the immune system. Therefore, immunotherapeutics including vaccination and “protective autoimmunity” provide promising means to rejuvenate neuro-inflammatory disorders and repair CNS acute injury and chronic neuro-degeneration. We review the current understanding and recent discoveries linking the aging immune system with CNS injury and neuro-degeneration. Additionally, we discuss potential recovery and rejuvenation strategies, focusing on targeting the aging T cell immune system in an effort to alleviate acute brain injury and chronic neuro-degeneration during aging, via the “thymus-inflammaging-neurodegeneration axis”.

Correlation of Peripheral Immunity With Rapid Amyotrophic Lateral Sclerosis Progression

Importance

Amyotrophic lateral sclerosis (ALS) has an immune component, but previous human studies have not examined immune changes over time.

Objectives

To assess peripheral inflammatory markers in participants with ALS and healthy control individuals and to track immune changes in ALS and determine whether these changes correlate with disease progression.

Design, Setting, and Participants

In this longitudinal cohort study, leukocytes were isolated from peripheral blood samples from 35 controls and 119 participants with ALS at the ALS Clinic of the University of Michigan, Ann Arbor, from June 18, 2014, through May 26, 2016. Follow-up visits occurred every 6 to 12 months. Fifty-one participants with ALS provided samples at multiple points. Immune cell populations were measured and compared between control and ALS groups. Surface marker expression of CD11b+ myeloid cells was also assessed. Changes over time were correlated with disease progression using multivariate regression.

Main Outcomes and Measures

The number of immune cells per milliliter of blood and the fold expression of cell surface markers. Multivariate regression models were used to correlate changes in immune metrics with changes on the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R).

Results

Thirty-five controls (17 women [48.6%] and 18 men [51.4%]; mean [SD] age, 63.5 [9.9] years) and 119 participants with ALS (50 women [42.0%] and 69 men [68.0%]; mean [SD] age, 61.4 [11.5] years) were enrolled. Compared with controls, participants with ALS had increased mean (SEM) counts ( × 106/mL) of total leukocytes (4.57 [0.29; 95% CI, 3.94-5.11] vs 5.53 [0.16; 95% CI, 5.21-5.84]), neutrophils (2.87 [0.23; 95% CI, 2.40-3.35] vs 3.80 [0.12; 95% CI, 3.56-4.04]), CD16+ monocytes (0.03 [0.003; 95% CI, 0.02-0.04] vs 0.04 [0.002; 95% CI, 0.03-0.04]), CD16- monocytes (0.25 [0.02; 95% CI, 0.21-0.30] vs 0.29 [0.01; 95% CI, 0.27-0.31]), and natural killer cells (0.13 [0.02; 95% CI, 0.10-0.17] vs 0.18 [0.01; 95% CI, 0.16-0.21]). We also observed an acute, transient increase in a population of CD11b+ myeloid cells expressing HLA-DR, CD11c, and CX3CR1. Finally, early changes in immune cell numbers had a significant correlation with disease progression measured by change in ALSFRS-R score, particularly neutrophils (-4.37 [95% CI, -6.60 to -2.14] per 11.47 × 104/mL [SD, 58.04 × 104/mL] per year) and CD4 T cells (-30.47 [95% CI, -46.02 to -14.94] per -3.72 × 104/mL [SD, 26.21 × 104/mL] per year).

Conclusions and Relevance

Changes in the immune system occur during ALS and may contribute to the pathologic features of ALS.

Slowing disease progression in the SOD1 mouse model of ALS by blocking neuregulin-induced microglial activation

There are no effective treatments to slow disease progression in ALS. We previously reported that neuregulin (NRG) receptors are constitutively activated on microglia in the ventral horns in both ALS patients and SOD1 mice and in the corticospinal tracts of ALS patients, and that NRG receptor activation occurs prior to significant clinical disease onset in SOD1 mice. Here, we hypothesize that blocking NRG signaling on microglia would slow disease progression in SOD1 mice using a targeted NRG antagonist (HBD-S-H4). Recombinant HBD-S-H4 directly delivered into the central nervous system (CNS) through implanted intracerebroventricular cannulas showed no signs of toxicity and significantly inhibited NRG receptor activation on microglia resulting in reduced microglial activation and motor neuron loss. The treatment also resulted in a delay in disease onset and an increase in survival. The therapeutic effect was dose-dependent that varied as a function of genetic background in two different strains of SOD1 mice. As a complementary drug delivery approach, transgenic mice expressing HBD-S-H4 driven by an astrocytic promoter (GFAP) had slower disease progression in a dose dependent manner, based on the level of HBD-S-H4 expression. These studies provide mechanistic insights into how NRG signaling on microglia may lead to disease progression and demonstrate the utility of a humanized fusion protein that blocks NRG as a novel therapeutic for human ALS.

CNS inflammation and neurodegeneration

There is an increasing recognition that inflammation plays a critical role in neurodegenerative diseases of the CNS, including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and the prototypic neuroinflammatory disease multiple sclerosis (MS). Differential immune responses involving the adaptive versus the innate immune system are observed at various stages of neurodegenerative diseases, and may not only drive disease processes but could serve as therapeutic targets. Ongoing investigations into the specific inflammatory mechanisms that play roles in disease causation and progression have revealed lessons about inflammation-driven neurodegeneration that can be applied to other neurodegenerative diseases. An increasing number of immunotherapeutic strategies that have been successful in MS are now being applied to other neurodegenerative diseases. Some approaches suppress CNS immune mechanisms, while others harness the immune system to clear deleterious products and cells. This Review focuses on the mechanisms by which inflammation, mediated either by the peripheral immune response or by endogenous CNS immune mechanisms, can affect CNS neurodegeneration.

Phase IIa trial of fingolimod for amyotrophic lateral sclerosis demonstrates acceptable acute safety and tolerability

Introduction

Immune activation has been implicated in progression of amytrophic lateral sclerosis (ALS). Oral fingolimod reduces circulating lymphocytes. The objective of this phase IIa, randomized, controlled trial was to test the short‐term safety, tolerability, and target engagement of fingolimod in ALS.

Methods

Randomization was 2:1 (fingolimod:placebo). Treatment duration was 4 weeks. Primary outcomes were safety and tolerability. Secondary outcomes included circulating lymphocytes and whole‐blood gene expression.

Results

Thirty participants were randomized; 28 were administered a drug (fingolimod 18, placebo 10). No serious adverse events occurred. Adverse events were similar by treatment arm, as was study discontinuation (2 fingolimod vs. 0 placebo, with no statistical difference). Forced expiratory volume in 1 second (FEV₁) and FEV₁/slow vital capacity changes were similar in the fingolimod and placebo arms. Circulating lymphocytes decreased significantly in the fingolimod arm (P < 0.001). Nine immune‐related genes were significantly downregulated in the fingolimod arm, including forkhead box P3 (P < 0.001) and CD40 ligand (P = 0.003).

Discussion

Fingolimod is safe and well‐tolerated and can reduce circulating lymphocytes in ALS patients. Muscle Nerve56: 1077–1084, 2017