Regulatory T-lymphocytes mediate amyotrophic lateral sclerosis progression and survival

Efficacy and safety of low-dose IL-2 as an add-on therapy to riluzole (MIROCALS): a phase 2b, double-blind, randomised, placebo-controlled trial

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a life-threatening disease characterised by progressive loss of motor neurons with few therapeutic options. The MIROCALS study tested the hypothesis that low-dose interleukin-2 (IL-2LD) improves survival and function in ALS.

METHODS

In this randomised, double-blind, placebo-controlled trial, male and female riluzole-naive participants, with either a possible, laboratory-supported probable, probable, or definite ALS diagnosis (revised El Escorial criteria), aged 18-76 years, with symptom duration of 24 months or fewer, and slow vital capacity of 70% or more, underwent a riluzole-only 12-18 week run-in period before randomisation in a 1:1 ratio to either 2 million international units (MIU) IL-2LD or placebo by subcutaneous injection daily for 5 days every 28 days over 18 months. The primary endpoint was survival at 640 days (21 months). Secondary outcomes included safety, ALS Functional Rating Scale-Revised (ALSFRS-R) score, and biomarker measurements including regulatory T-cells (Tregs), cerebrospinal fluid (CSF)-phosphorylated-neurofilament heavy-chain (CSF-pNFH), and plasma and CSF-chemokine ligand 2 (CCL2). The primary endpoint analysis used unadjusted log-rank and Cox's model adjusted analyses using pre-defined prognostic covariates to control for the disease and treatment response heterogeneity. The study was 80% powered to detect a two-fold decrease in the risk of death by the log-rank test in the intention-to-treat (ITT) population, including all randomly allocated participants. MIROCALS is registered with ClinicalTrials.gov (NCT03039673) and is complete.

FINDINGS

From June 19, 2017, to Oct 16, 2019, 304 participants were screened, of whom 220 (72%) met all criteria for random allocation after the 12-to-18-week run-in period on riluzole. 136 (62%) of participants were male and 84 participants (38%) were female. 25 (11%) of the 220 randomly allocated participants were defined as having possible ALS under El Escorial criteria. At the cutoff date there was no loss to follow-up, and all 220 patients who were randomly allocated were documented as either deceased (90 [41%]) or alive (130 [59%]), so all participants were included in the ITT and safety populations. The primary endpoint unadjusted analysis showed a non-significant 19% decrease in risk of death with IL-2LD (hazard ratio 0·81 [95% CI 0·54-1·22], p=0·33), failing to demonstrate the expected two-fold decrease in risk of death. The analysis of the primary endpoint adjusted on prognostic covariates, all measured at time of random allocation, showed a significant decrease of the risk of death with IL-2LD (0·32 [0·14-0·73], p=0·007), with a significant treatment by CSF-pNFH interaction (1·0003 [1·0001-1·0005], p=0·001). IL-2LD was safe, and significantly increased Tregs and decreased plasma-CCL2 at all timepoints. Stratification on CSF-pNFH levels measured at random allocation showed that IL-2LD was associated with a significant 48% decrease in risk of death (0·52 [0·30-0·89], p=0·016) in the 70% of the population with low (750-3700 pg/mL) CSF-pNFH levels, while in the 21% with high levels (>3700 pg/mL), there was no significant difference (1·37 [0·68-2·75], p=0·38).

INTERPRETATION

With this treatment schedule, IL-2LD resulted in a non-significant reduction in mortality in the primary unadjusted analysis. However, the difference between the results of unadjusted and adjusted analyses of the primary endpoint emphasises the importance of controlling for disease heterogeneity in ALS randomised controlled trials. The decrease in risk of death achieved by IL-2LD therapy in the trial population with low CSF-pNFH levels requires further investigation of the potential benefit of this therapy in ALS.

FUNDING

European Commission H2020 Programme; French Health Ministry PHRC2014; and Motor Neurone Disease Association.

Altered microbiome influence on the enteric neuromuscular system in amyotrophic lateral sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is a neurological disease marked by the degeneration of motor neurons, leading to muscle weakness and paralysis. While the cause of ALS is uncertain, research indicates that changes in the gut microbiome may influence the disease's progression. This chapter explores how alterations in gut microbiota affect the enteric neuromuscular system (ENS) in ALS. In ALS patients, disrupted gut microbiota are linked to the brain-gut axis, impacting both gastrointestinal function and neuronal health. Studies show that microbial changes are associated with inflammation, immune instability, and neurodegeneration, which exacerbate the disease. Gastrointestinal issues like constipation and dysphagia in ALS are tied to ENS dysregulation. Understanding the connections between the gut microbiome, ENS, and central nervous system (CNS) may lead to novel therapies targeting neurodegeneration and microbial dysbiosis in ALS.

Pathological forms of TDP-43 in amyotrophic lateral sclerosis (ALS) promote aberrant telomere elongation

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting motor neurons. TAR DNA-binding protein 43 (TDP-43) mis-localisation from the nucleus to the cytoplasm is the major pathological characteristic of ALS. Telomeres are repetitive DNA sequences found in complex with proteins at chromosomal ends. The shelterin protein complex protects telomeres from DNA damage by producing characteristic t-loop structures, and telomere repeat binding factor 2 (TRF2) has an essential role in this process. Telomere dysregulation is reported in ALS, but conflicting findings have been obtained. Here we examined if telomere dysregulation is present in cortical neurons in a mouse model with pathological mis-localisation of TDP-43 to the cytoplasm - TDP-43 rNLS - compared to controls, and in cortical primary neurons expressing TDP-43 ALS associated mutations (A315T, A90V). We demonstrate that telomeres are significantly longer and of more variable in length in the TDP-43 rNLS model compared to controls. This was proceeded by downregulation of TRF2 in early disease stages with subsequent upregulation of TRF2 at advanced disease in TDP-43 rNLS mice. Longer telomeres were also present in primary cortical neurons expressing mutant TDP-43. A trend towards TRF2 upregulation was also present in human ALS spinal cord lysates. We detected dysregulation of catalytic subunit of telomerase, TERT, and a trend towards upregulation of telomere interacting protein, Rif 1 in these mice and human ALS spinal cord lysates. The longer telomeres were independent of the alternative lengthening of telomeres (ALT) mechanism of maintaining telomere length. Similarly, no DNA damage at telomere sites was detected. Our findings imply that telomere protection is compromised in ALS, leading to longer telomeres in neurons in ALS associated with TDP-43 pathology.

Clinical Safety and Preliminary Efficacy of Regulatory T Cells for ALS

BACKGROUND

Peripheral and neuroinflammation have been previously associated with progression in amyotrophic lateral sclerosis (ALS), a neurodegenerative disease involving progressive loss of motor neurons. We hypothesize that regulatory T cell (Treg) therapy can resolve inflammation and preserve function in those patients with ALS.

METHODS

Participants with ALS received infusions of a fixed dose (100×106 cells) of umbilical cord blood-derived, allogeneic, nonhuman leukocyte antigen-matched, cryopreserved Treg product (TREG), administered as four weekly infusions followed by six monthly infusions. No lymphodepletion, immunosuppression, or interleukin 2 was administered. The primary outcome was dose-limiting toxicity, including infusion reaction within 24 hours (as graded by National Cancer Institute - Common Terminology Criteria for Adverse Events, Version 4.0) and/or regimen-related death, or grade 3 or 4 cytokine release syndrome within 14 days postinfusion. We measured clinical response using the Revised ALS Functional Rating Scale (ALSFRS-R; range 0 to 48, with lower numbers indicating lower functional ability). Exploratory analyses measured serum and plasma neurofilament light (NfL) and inflammatory biomarkers.

RESULTS

Six participants with a median age of 48.5 years (range 27 to 66 years) and baseline ALSFRS-R score of 31.5 (range 23 to 43) were treated with a median of 11 (range 6 to 22) TREG infusions in an ambulatory setting. No dose-limiting toxicity was observed. In participants with sufficient data points (n=4), the mean ALSFRS-R slope of decline was -1.66±1.03 points/month before treatment, -0.41±0.45/month during treatment, and -0.60±0.59/month posttreatment. Biomarkers including NfL and inflammatory markers MIP-1δ (macrophage inflammatory protein-1 delta), CTACK (cutaneous T cell-attracting chemokine), and GROα (growth-regulated oncogene alpha) exhibited different relationships with ALSFRS-R score between participants.

CONCLUSIONS

This study demonstrates the preliminary safety of "off-the-shelf", allogeneic Treg-cell therapy.

Neuroinflammation and Amyotrophic Lateral Sclerosis: Recent Advances in Anti-Inflammatory Cytokines as Therapeutic Strategies

Neuroinflammation is an inflammatory response occurring within the central nervous system (CNS). The process is marked by the production of pro-inflammatory cytokines, chemokines, small-molecule messengers, and reactive oxygen species. Microglia and astrocytes are primarily involved in this process, while endothelial cells and infiltrating blood cells contribute to neuroinflammation when the blood-brain barrier (BBB) is damaged. Neuroinflammation is increasingly recognized as a pathological hallmark of several neurological diseases, including amyotrophic lateral sclerosis (ALS), and is closely linked to neurodegeneration, another key feature of ALS. In fact, neurodegeneration is a pathological trigger for inflammation, and neuroinflammation, in turn, contributes to motor neuron (MN) degeneration through the induction of synaptic dysfunction, neuronal death, and inhibition of neurogenesis. Importantly, resolution of acute inflammation is crucial for avoiding chronic inflammation and tissue destruction. Inflammatory processes are mediated by soluble factors known as cytokines, which are involved in both promoting and inhibiting inflammation. Cytokines with anti-inflammatory properties may exert protective roles in neuroinflammatory diseases, including ALS. In particular, interleukin (IL)-10, transforming growth factor (TGF)-β, IL-4, IL-13, and IL-9 have been shown to exert an anti-inflammatory role in the CNS. Other recently emerging immune regulatory cytokines in the CNS include IL-35, IL-25, IL-37, and IL-27. This review describes the current understanding of neuroinflammation in ALS and highlights recent advances in the role of anti-inflammatory cytokines within CNS with a particular focus on their potential therapeutic applications in ALS. Furthermore, we discuss current therapeutic strategies aimed at enhancing the anti-inflammatory response to modulate neuroinflammation in this disease.

Early immune system changes in amyotrophic lateral sclerosis correlate with later disease progression

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease with no cure and limited treatment options. The immune system is implicated in disease pathology, unlocking a potential therapeutic avenue. However, it is unclear whether immune changes are a cause or consequence of disease progression.

METHODS

Peripheral immune cells were longitudinally measured at monthly intervals in 55 ALS and 50 control participants. 22 peripheral immune markers in the blood were assessed using flow cytometry, and clinical progression was assessed using the revised ALS functional rating scale (ALSFRS-R). Individual immune markers, their trajectories, and overall variability were compared in ALS versus control participants; ALS participants were also stratified by clinical progression rates and assessed similarly across progression groups. Finally, a novel, lagged linear regression model correlated the rate of immune changes to subsequent downstream ALSFRS-R changes.

FINDINGS

Numerous immune markers were dysregulated in ALS versus control participants, with altered levels, trajectories, or variability in immune populations and surface markers. ALS participants had increased immune variability relative to control participants; within ALS participants, faster progressors overall had decreased marker variability. Finally, natural killer (NK) cell numbers, NK cell subpopulations, and NK cell surface markers were significantly associated with downstream ALS progression.

CONCLUSIONS

The immune system is dysregulated in ALS and more consistently dysregulated in faster ALS progression, and immune dysregulation occurs upstream of clinical changes. These findings suggest that the immune system is a causal factor of ALS progression in human patients.

FUNDING

CReATe Consortium, NIH, Target ALS, DoD, ALSA.

Gene therapy breakthroughs in ALS: a beacon of hope for 20% of ALS patients

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease that remains incurable. Although the etiologies of ALS are diverse and the precise pathogenic mechanisms are not fully understood, approximately 20% of ALS cases are caused by genetic factors. Therefore, advancing targeted gene therapies holds significant promise, at least for the 20% of ALS patients with genetic etiologies. In this review, we summarize the main strategies and techniques of current ALS gene therapies based on ALS risk genes, and review recent findings from animal studies and clinical trials. Additionally, we highlight ALS-related genes with well-understood pathogenic mechanisms and the potential of numerous emerging gene-targeted therapeutic approaches for ALS.

Targeting common disease pathomechanisms to treat amyotrophic lateral sclerosis

The motor neuron disease amyotrophic lateral sclerosis (ALS) is a devastating condition with limited treatment options. The past few years have witnessed a ramping up of translational ALS research, offering the prospect of disease-modifying therapies. Although breakthroughs using gene-targeted approaches have shown potential to treat patients with specific disease-causing mutations, the applicability of such therapies remains restricted to a minority of individuals. Therapies targeting more general mechanisms that underlie motor neuron pathology in ALS are therefore of considerable interest. ALS pathology is associated with disruption to a complex array of key cellular pathways, including RNA processing, proteostasis, metabolism and inflammation. This Review details attempts to restore cellular homeostasis by targeting these pathways in order to develop effective, broadly-applicable ALS therapeutics.

Immune mechanisms and shared immune targets in neurodegenerative diseases

The immune system plays a major part in neurodegenerative diseases. In some, such as multiple sclerosis, it is the primary driver of the disease. In others, such as Alzheimer disease, amyotrophic lateral sclerosis and Parkinson disease, it has an amplifying role. Immunotherapeutic approaches that target the adaptive and innate immune systems are being explored for the treatment of almost all neurological diseases, and the targets and approaches are often common across diseases. Microglia are the primary immune cells in the brain that contribute to disease pathogenesis, and are consequently a common immune target for therapy. Other therapeutic approaches target components of the peripheral immune system, such as regulatory T cells and monocytes, which in turn act within the CNS. This Review considers in detail how microglia, monocytes and T cells contribute to the pathogenesis of multiple sclerosis, Alzheimer disease, amyotrophic lateral sclerosis and Parkinson disease, and their potential as shared therapeutic targets across these diseases. The microbiome is also highlighted as an emerging therapeutic target that indirectly modulates the immune system. Therapeutic approaches being developed to target immune function in neurodegenerative diseases are discussed, highlighting how immune-based approaches developed to treat one disease could be applicable to multiple other neurological diseases.

Tregs levels and phenotype modifications during Amyotrophic Lateral Sclerosis course

Introduction

T regulatory cells (Tregs) inversely correlate with disease progression in Amyotrophic Lateral Sclerosis (ALS) and fast-progressing ALS patients have been reported to exhibit dysfunctional, as well as reduced, levels of Tregs. This study aimed to evaluate the longitudinal changes in Tregs among ALS patients, considering potential clinical and biological modifiers of their percentages and concentrations. Additionally, we explored whether measures of ALS progression, such as the decline over time in the revised ALS Functional Rating Scale (ALSFRS-r) or forced vital capacity (FVC) correlated Treg levels and whether Treg phenotype varied during the course of ALS.

Methods

Total Tregs (detected by CD3, CD4, FoxP3, CD25, and CD127) were quantified at five time points over 54 weeks in 21 patients in the placebo arm of the RAP-ALS trial; next they were characterized for the expression of surface markers including CD38, CD39, CXCR3, and PD1. Repeated measures mixed models were used to analyze the longitudinal course of Tregs, considering potential associations with other clinical and laboratory characteristics. Correlations between ALSFRS-r or FVC and Tregs over time were similarly investigated.

Results

Our study showed that Treg levels did not change significantly on average during the observation period in our ALS cohort. However, PD1+Tregs decreased and CD39+Tregs increased over time. Male sex and cholesterol levels were associated with increasing Tregs (%) over time, while monocytes positively affected Treg concentrations. Treg concentrations showed a modesty association with FVC decline but were not associated with ALSFRS-r decline.

Discussion

Treg levels remained stable during the ALS observation period and were not significantly associated with ALSFRS-r variations, suggesting that Treg numbers alone may have limited utility as a pharmaco-dynamic biomarker for ALS trials. However the observed changes in Treg phenotypes, such as the decrease in PD1+Tregs, indicate that phenotypic variations may warrant further investigation for their potential role in ALS progression and therapeutic targeting.

Rising Voltage-Gated Potassium Channel Antibody Level as a Possible Disease Progression Marker for Amyotrophic Lateral Sclerosis: A Case Report

A subset of amyotrophic lateral sclerosis (ALS) patients tests positive for antibodies commonly associated with autoimmune neurological diseases, including voltage-gated potassium channel (VGKC)-complex antibodies. Although an autoimmune basis for ALS remains speculative, and immunomodulatory therapies have shown minimal benefit as of yet, isolated cases suggest that VGKC-complex antibodies may be relevant to disease type and progression. In this report, we present a case of ALS in which increasing VGKC-complex antibody levels correlated with clinical decline, raising the question of whether such antibodies could serve as biomarkers of progression in VGKC-complex antibody-positive ALS patients. To date, no published studies have systematically evaluated changes in VGKC-complex antibody levels in ALS patients over time. Our findings suggest that tracking VGKC-complex antibodies in ALS may offer insights into disease progression and prompt further investigation into their potential role as prognostic biomarkers, especially in certain subtypes of the disease.

Neuroglia in neurodegeneration: Amyotrophic lateral sclerosis and frontotemporal dementia

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are devastating neurodegenerative diseases sharing significant pathologic and genetic overlap, leading to consider these diseases as a continuum in the spectrum of their pathologic features. Although FTD compromises only specific brain districts, while ALS involves both the nervous system and the skeletal muscles, several neurocentric mechanisms are in common between ALS and FTD. Also, recent research has revealed the significant involvement of nonneuronal cells, particularly glial cells such as astrocytes, oligodendrocytes, microglia, and peripheral immune cells, in disease pathology. This chapter aims to provide an extensive overview of the current understanding of the role of glia in the onset and advancement of ALS and FTD, highlighting the recent implications in terms of prognosis and future treatment options.

Th17 and effector CD8 T cells relate to disease progression in amyotrophic lateral sclerosis: a case control study

The immune system has garnered attention due to its association with disease progression in amyotrophic lateral sclerosis (ALS). However, the role of peripheral immune cells in this context remains controversial. Here, we conducted single-cell RNA-sequencing of peripheral blood mononuclear cells to comprehensively profile immune cells concerning the rate of disease progression in patients with ALS. Our analysis revealed increased frequencies of T helper 17 cells (Th17) relative to regulatory T cells, effector CD8 T cells relative to naïve CD8 T cells, and CD16highCD56low mature natural killer cells relative to CD16lowCD56high naïve natural killer cells in patients with rapidly progressive ALS. Additionally, we employed serum proteomics through a proximity extension assay combined with next-generation sequencing to identify inflammation-related proteins associated with rapid disease progression. Among these proteins, interleukin-17 A correlated with the frequency of Th17, while killer cell lectin-like receptor D1 (CD94) correlated with the frequency of effector CD8 T cells. These findings further support the active roles played by these specific immune cell types in the progression of ALS.

Circulating Levels of T-Cell Traits and the Risk of Amyotrophic Lateral Sclerosis: A Mendelian Randomization Study

Amyotrophic lateral sclerosis (ALS) represents a rare and potentially fatal neurodegenerative disease. Diverse T-cell subsets could potentially exert diametrically opposite impacts upon ALS development. A two-sample Mendelian randomization (MR) analysis was performed to investigate the correlation between 244 T-cell subsets and ALS risk. Genetic instrumental variables were procured from a standard genome-wide association study (GWAS) that encompassed 244 T-cell subsets in 3757 individuals of European lineage. ALS-related data were collected from a GWAS comprising 20,806 ALS instances and 59,804 European control participants. Multiple sensitivity analyses were performed to verify the robustness of the significant results. Reverse MR analysis was used for delineating the effects of ALS on the characteristics of T-cells. After multiple comparison corrections, 24 out of the 244 subtypes demonstrated a potential association with ALS risk. Significantly, 75% of these associations encompassed the expression of the CD3 on diverse T-cell subtypes, revealing a highly consistent inverse relation to ALS risk. The proportion of T regulatory cells (Tregs) in CD4+ T cells and secreting Tregs in CD4+ T cells demonstrated negative associations with the risk of ALS. CCR7 expression on naive CD4+ T cells and CCR7 expression on naive CD8+ T cells showed positive associations with ALS risk. Certain T-cell subsets, particularly those identified by CD3 expression on terminally differentiated CD8+ T cells, proportions of Tregs, and CCR7 expression, indicated an association with ALS risk. These findings harmonize with and extend previous observational studies investigating the involvement of T lymphocyte subset-induced immunological processes in ALS.

Gut microbiota immune cross-talk in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of motor neurons. While there has been significant progress in defining the genetic contributions to ALS, greater than 90 ​% of cases are sporadic, which suggests an environmental component. The gut microbiota is altered in ALS and is an ecological factor that contributes to disease by modulating immunologic, metabolic, and neuronal signaling. Depleting the microbiome worsens disease in the SOD1 ALS animal model, while it ameliorates disease in the C9orf72 model of ALS, indicating critical subtype-specific interactions. Furthermore, administering beneficial microbiota or microbial metabolites can slow disease progression in animal models. This review discusses the current state of microbiome research in ALS, including interactions with different ALS subtypes, evidence in animal models and human studies, key immunologic and metabolomic mediators, and a path toward microbiome-based therapies for ALS.

Effect of ultrasound-mediated blood-spinal cord barrier opening on survival and motor function in females in an amyotrophic lateral sclerosis mouse model

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by a progressive loss of motor neurons. The limited efficacy of recent therapies in clinical development may be linked to lack of drug penetration to the affected motor neurons due to the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB).

METHODS

In this work, the safety and efficacy of repeated short transient opening of the BSCB by low intensity pulsed ultrasound (US, sonication) was studied in females of an ALS mouse model (B6.Cg-Tg(SOD1∗G93A)1Gur/J). The BSCB was disrupted using a 1 MHz ultrasound transducer coupled to the spinal cord, with and without injection of insulin-like growth factor 1 (IGF1), a neurotrophic factor that has previously shown efficacy in ALS models.

FINDINGS

Results in wild-type (WT) animals demonstrated that the BSCB can be safely disrupted and IGF1 concentrations significantly enhanced after a single session of transient BSCB disruption (176 ± 32 μg/g vs. 0.16 ± 0.008 μg/g, p < 0.0001). Five repeated weekly US sessions performed in female ALS mice demonstrated a survival advantage in mice treated with IGF1 and US (US IGF1) compared to treatment with IGF1 alone (176 vs. 166 days, p = 0.0038). Surprisingly, this survival advantage was also present in mice treated with US alone vs. untreated mice (178.5 vs. 166.5 days, p = 0.0061). Muscle strength did not show difference among the groups. Analysis of glial cell immunoreactivity and microglial transcriptome showing reduced cell proliferation pathways, in addition to lymphocyte infiltration, suggested that the beneficial effect of US or US IGF1 could act through immune cell modulation.

INTERPRETATION

These results show the first step towards a possible beneficial impact of transient BSCB opening for ALS therapy and suggest implication of immune cells.

FUNDING

Fondation pour la Recherche Médicale (FRM). Investissements d'avenirANR-10-IAIHU-06, Société Française de Neurochirurgie (SFNC), Fond d'étude et de Recherche du Corps Medical (FERCM), Aide à la Recherche des Maladies du Cerveau (ARMC), SLA Fondation Recherche (SLAFR), French Ministry for High Education and Research (MENR), Carthera, Laboratoire de Recherche en Technologies Chirurgicales Avancées (LRTCA).

Peripheral immunity relate to disease progression and prognosis in amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Abnormalities in the peripheral immune system in ALS have been paid attention; however, the results of changes in peripheral immune parameters were inconsistent.

METHODS

A total of 1109 ALS patients were enrolled in the study. All patients received clinical evaluation and peripheral immune parameters measurement. The outcomes were analyzed by correlation analysis, multiple linear regression and cox survival analysis.

RESULTS

We found that ALS patients had significantly higher percentage of CD4+ T cells (39.3 vs. 37.1%, p < 0.001) and CD4+/CD8+ ratio (1.88 vs. 1.72, p = 0.011), significantly lower IgG (11.73 vs.12.82, p < 0.001) and IgA (2130.70 vs. 2284.8, p = 0.013) compared with the health controls. In the multivariate linear model, we found that each increase of 1.262, 0.278, and 4.44E-4 in ALSFRS-R scores were significantly associated with each increment of lymphocyte count, IgG, and IgA, respectively. However, each decrease of 0.341, 0.068, and 0.682 in ALSFRS-R score was associated with each increment in neutrophils, CD4+ T cells, and CD4+/CD8+ ratio, respectively. Cox survival regression analysis showed that the death risk of ALS patients was related to the levels of C3 (HR 0.592, 95% CI 0.361-0.973).

CONCLUSION

We found that there were differences in peripheral immune parameters of ALS patients with the severity of the disease, especially neutrophil, lymphocyte, CD4+ T, and IgG; C3 is an independent predictor of survival in ALS patients. More studies are needed to elucidate the mechanisms associated with altered immune parameters in ALS.

T cell subset composition differs between blood and cerebrospinal fluid in amyotrophic lateral sclerosis

Inflammation is a hallmark of amyotrophic lateral sclerosis (ALS) and is often assessed through biological samples. Due to the easier access, peripheral blood is more commonly phenotyped instead of cerebrospinal fluid (CSF) or affected tissues in ALS. Here, using flow cytometry, we compared the composition of T cell subsets in blood and CSF in ALS patients. We found consistent but weak correlations between blood and CSF for all T cell subsets examined. This finding implies that blood and CSF offer complementary information when characterizing T cell immunity in ALS and blood may not be used as a surrogate for CSF.

The Current Landscape of Hypotheses Describing the Contribution of CD4+ Heterogeneous Populations to ALS

Amyotrophic Lateral Sclerosis (ALS) is a poorly understood and fatal disease. It has a low prevalence and a 2-4 year survival period. Various theories and hypotheses relating to its development process have been proposed, albeit with no breakthrough in its treatment. Recently, the role of the adaptive immune system in ALS, particularly CD4+ T cells, has begun to be investigated. CD4+ T cells are a heterogeneous group of immune cells. They include highly pro-inflammatory types such as Th1 and Th17, as well as highly anti-inflammatory cells such as Tregs. However, the landscape of the role of CD4+ T cells in ALS is still not clearly understood. This review covers current hypotheses that elucidate how various CD4+ T cells can contribute to ALS development. These hypotheses include the SWITCH model, which suggests that, in the early stages of the disease, Tregs are highly capable of regulating the immune response. However, in the later stages of the disease, it seems that pro-inflammatory cells such as Th1 and Th17 are capable of overwhelming Treg function. The reason why this occurs is not known. Several research groups have proposed that CD4+ T cells as a whole might experience aging. Others have proposed that gamma delta T cells might directly target Tregs. Additionally, other research groups have argued that less well-known CD4+ T cells, such as Emoes+ CD4+ T cells, may be directly responsible for neuron death by producing granzyme B. We propose that the ALS landscape is highly complicated and that there is more than one feasible hypothesis. However, it is critical to take into consideration the differences in the ability of different populations of CD4+ T cells to infiltrate the blood-brain barrier, taking into account the brain region and the time of infiltration. Shedding more light on these still obscure factors can help to create a personalized therapy capable of regaining the balance of power in the battle between the anti-inflammatory and pro-inflammatory cells in the central nervous system of ALS patients.

Allogeneic B cell immunomodulatory therapy in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an orphan neurodegenerative disease. Immune system dysregulation plays an essential role in ALS onset and progression. Our preclinical studies have shown that the administration of exogenous allogeneic B cells improves outcomes in murine models of skin and brain injury through a process termed pligodraxis, in which B cells adopt an immunoregulatory and neuroprotective phenotype in an injured environment. Here, we investigated the effects of B-cell therapy in the SOD1G93A mouse preclinical model of ALS and in a person living with ALS. Purified splenic mature naïve B cells from haploidentical donor mice were administered intravenously in SOD1G93A mice for a total of 10 weekly doses. For the clinical study in a person with advanced ALS, IgA gammopathy of unclear significance, and B lymphopenia, CD19+ B cells were positively selected from a healthy haploidentical donor and infused intravenously twice, at a 60-day interval. Repeated intravenous B-cell administration was safe and significantly delayed disease onset, extended survival, reduced cellular apoptosis, and decreased astrogliosis in SOD1G93A mice. Repeated B-cell infusion in a person with ALS was safe and did not appear to generate a clinically evident inflammatory response. An improvement of 5 points on the ALSFRS-R scale was observed after the first infusion. Levels of inflammatory markers showed persistent reduction post-infusion. This represents a first demonstration of the efficacy of haploidentical B-cell infusion in the SOD1G93A mouse and the safety and feasibility of using purified haploidentical B lymphocytes as a cell-based therapeutic strategy for a person with ALS.

Pharmacometabolomics applied to low-dose interleukin-2 treatment in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease. The immunosuppressive functions of regulatory T lymphocytes (Tregs) are impaired in ALS, and correlate to disease progression. The phase 2a IMODALS trial reported an increase in Treg number in ALS patients following the administration of low-dose (ld) interleukin-2 (IL-2). We propose a pharmacometabolomics approach to decipher metabolic modifications occurring in patients treated with ld-IL-2 and its relationship with Treg response. Blood metabolomic profiles were determined on days D1, D64, and D85 from patients receiving 2 MIU of IL-2 (n = 12) and patients receiving a placebo (n = 12). We discriminated the three time points for the treatment group (average error rate of 42%). Among the important metabolites, kynurenine increased between D1 and D64, followed by a reduction at D85. The percentage increase of Treg number from D1 to D64, as predicted by the metabolome at D1, was highly correlated with the observed value. This study provided a proof of concept for metabolic characterization of the effect of ld-IL-2 in ALS. These data could present advances toward a personalized medicine approach and present pharmacometabolomics as a key tool to complement genomic and transcriptional data for drug characterization, leading to systems pharmacology.

Use of biomarkers in clinical trials and future developments that will help identify novel biomarkers

Engineering new solutions for therapeutic benefit in Amyotrophic Lateral Sclerosis (ALS) has proved a difficult task to accomplish. This is largely the reflection of complexities at multiple levels, that require solutions to improve cost-effectiveness and outcomes. The main obstacle related to the condition's clinical heterogeneity, chiefly the broad difference in survival observed among ALS patients, imposes large populations studies and long follow-up to evaluate any efficacy. The emerging solution is composite clinical and biological parameters enabling prognostic stratification into homogeneous phenotypes for more affordable studies. From a therapeutic development perspective, the choice of a medicinal product requires the availability of treatment-specific biomarkers of target engagement to identify off-target effects based on the compound's putative modality of action. More importantly, there are no established biomarkers of treatment response that can complement clinical outcome measures and support futility and end of treatment analyses of efficacy. Ultimately the onus rests on the development of biomarkers encompassing the unmet needs of clinical trial design, from inclusion to efficacy. These readouts of the pathological process may be used in combination with clinical and paraclinical outcome measured, significantly reducing the time and financial burden of clinical studies. Progress towards a biomarker-driven clinical trial design in ALS has been possible thanks to the accurate detection of neurofilaments and of other immunological mediators in biological fluids with the disease progression, a step change enabling the testing of novel therapeutic agents in a new clinical trial setting. However, further progress remains to be made to find treatment specific target engagement biomarkers along with readouts of treatment response that can be reliably applied to all emerging therapies and clinical studies. Here we will cover the basic notions of biomarker development in ALS clinical trials, the most crucial unanswered questions and the unmet needs in the ALS biomarkers space.

Current neuroprotective therapies and future prospects for motor neuron disease

Four medications with neuroprotective disease-modifying effects are now in use for motor neuron disease (MND). With FDA approvals for tofersen, relyvrio and edaravone in just the past year, 2022 ended a quarter of a century when riluzole was the sole such drug to offer to patients. The acceleration of approvals may mean we are witnessing the beginning of a step-change in how MND can be treated. Improvements in understanding underlying disease biology has led to more therapies being developed to target specific and multiple disease mechanisms. Consideration for how the pipeline of new therapeutic agents coming through in clinical and preclinical development can be more effectively evaluated with biomarkers, advances in patient stratification and clinical trial design pave the way for more successful translation for this archetypal complex neurodegenerative disease. While it must be cautioned that only slowed rates of progression have so far been demonstrated, pre-empting rapid neurodegeneration by using neurofilament biomarkers to signal when to treat, as is currently being trialled with tofersen, may be more effective for patients with known genetic predisposition to MND. Early intervention with personalized medicines could mean that for some patients at least, in future we may be able to substantially treat what is considered by many to be one of the most distressing diseases in medicine.

Induction of FoxP3 Pre-mRNA Alternative Splicing to Enhance the Suppressive Activity of Regulatory T Cells from Amyotrophic Lateral Sclerosis Patients

Forkhead box protein 3 (FoxP3) is a key transcription factor responsible for the development, maturation, and function of regulatory T cells (Tregs). The FoxP3 pre-mRNA is subject to alternative splicing, resulting in the translation of multiple splice variants. We have shown that Tregs from patients with amyotrophic lateral sclerosis (ALS) have reduced expression of full-length (FL) FoxP3, while other truncated splice variants are expressed predominantly. A correlation was observed between the reduced number of Tregs in the peripheral blood of ALS patients, reduced total FoxP3 mRNA, and reduced mRNA of its FL splice variant. Induction of FL FoxP3 was achieved using splice-switching oligonucleotides capable of base pairing with FoxP3 pre-mRNA and selectively modulating the inclusion of exons 2 and 7 in the mature mRNA. Selective expression of FL FoxP3 resulted in the induction of CD127low, CD152, and Helios-positive cells, while the cell markers CD4 and CD25 were not altered. Such Tregs had an increased proliferative activity and a higher frequency of cell divisions per day. The increased suppressive activity of Tregs with the induced FL FoxP3 splice variant was associated with the increased synthesis of the pro-apoptotic granzymes A and B, and perforin, IL-10, and IL-35, which are responsible for contact-independent suppression, and with the increased ability to suppress telomerase in target cells. The upregulation of Treg suppressive and proliferative activity using splice-switching oligonucleotides to induce the predominant expression of the FoxP3 FL variant is a promising approach for regenerative cell therapy in Treg-associated diseases.

Autophagy dysregulation plays a crucial role in regulatory T-cell loss and neuroinflammation in amyotrophic lateral sclerosis (ALS)

OBJECTIVE

Neuroinflammation is the hallmark of amyotrophic lateral sclerosis (ALS) disease. Regulatory T cells (Tregs) are essential in immune tolerance and neuroinflammation prevention. It has been shown that a significant decrease in Treg and FoxP3 protein expression is observed in ALS patients. The main reason for the FoxP3+ Treg loss in ALS is unknown. In this study, the role of autophagy dysregulation in FoxP3+ Tregs in ALS was investigated.

METHODS

Twenty-three ALS patients and 24 healthy controls were recruited for the study. Mononuclear cells (MNCs) were obtained from peripheral blood, and then Tregs were isolated. Isolated Tregs were stained with FoxP3 and LC3 antibodies and analyzed in flow cytometry to determine autophagy levels in FoxP3+ Tregs in patients and controls.

RESULTS

The mean of FoxP3+ LC3+ cells, were 0.47 and 0.45 in patients and controls, respectively. The mean of FoxP3+ LC3- cells was 0.15 in patients and 0.20 in controls, p = 0.030 (p < 0.05). There is no significant correlation between ALSFRS-R decay rate and autophagy level in patients. Also, there is no significant difference between autophagy levels in FoxP3+ Tregs in patients with rapidly progressing ALS and slow-progressing ALS.

CONCLUSION

Excessive autophagy levels in FoxP3+ Tregs in ALS patients can potentially be an explanation for an increased cell death and result in worsened neuroinflammation and disease onset. However, the disease progress is not attributable to autophagy levels in FoxP3+ Tregs.

CD4+ T-Cell Senescence in Neurodegenerative Disease: Pathogenesis and Potential Therapeutic Targets

With the increasing proportion of the aging population, neurodegenerative diseases have become one of the major health issues in society. Neurodegenerative diseases (NDs), including multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), are characterized by progressive neurodegeneration associated with aging, leading to a gradual decline in cognitive, emotional, and motor functions in patients. The process of aging is a normal physiological process in human life and is accompanied by the aging of the immune system, which is known as immunosenescence. T-cells are an important part of the immune system, and their senescence is the main feature of immunosenescence. The appearance of senescent T-cells has been shown to potentially lead to chronic inflammation and tissue damage, with some studies indicating a direct link between T-cell senescence, inflammation, and neuronal damage. The role of these subsets with different functions in NDs is still under debate. A growing body of evidence suggests that in people with a ND, there is a prevalence of CD4+ T-cell subsets exhibiting characteristics that are linked to senescence. This underscores the significance of CD4+ T-cells in NDs. In this review, we summarize the classification and function of CD4+ T-cell subpopulations, the characteristics of CD4+ T-cell senescence, the potential roles of these cells in animal models and human studies of NDs, and therapeutic strategies targeting CD4+ T-cell senescence.

Serum cytokines profile changes in amyotrophic lateral sclerosis

Background

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder, characterized by progressive limb weakness, dysphagia, dysphonia, and respiratory failure due to degeneration of upper and lower motor neurons. The pathogenesis of ALS is still unclear. Neuroinflammation has been found to be involved in its development and progression. Cytokines play a significant role in the inflammatory process. This study aims to identify novel biomarkers that may assist in the diagnosis of ALS.

Methods

In Fujian Medical University Union Hospital and Huashan Hospital Fudan University, two independent centers, we prospectively recruited 50 ALS patients, and 41 healthy controls (25 ALS and 26 controls in the first stage and 25 ALS and 15 controls in the validation stage). An 18-plex Luminex kit was used to screen the serum cytokines levels in the first stage. Commercial ELISA kits were used to measure the levels of target cytokines in the validation stage. A single-molecule array HD-X platform was applied to assess the levels of serum neurofilament light chain (NFL).

Results

The levels of serum IL-18 were markedly increased in patients with ALS in the first stage (p = 0.016). The ROC curve showed an area under the curve at 0.695 (95% CI 0.50-0.84) in distinguishing ALS patients from healthy controls. The IL-21 was decreased in elderly patients when grouped by 55 years old (the medium age). Furthermore, the IL-5, IL-13, IL-18, and NFL had a positive relationship with the disease progression of ALS. We also found that serum IL-18 was markedly increased in ALS patients in the validation stage (167.67 [148.25-175.59] vs 116.44 [102.43-122.19]pg/ml, p < 0.0015).

Conclusion

In this study, we identified systemic cytokine profile changes in the serum of ALS patients, especially the elevated IL-18, as well as the decreased IL-21 in elder patients. These changes in serum cytokine profiles may shed new light on an in-depth understanding of the immunopathogenic characteristics of ALS.

Optimal Therapeutic Strategy of Bone Marrow-Originated Autologous Mesenchymal Stromal/Stem Cells for ALS

Amyotrophic lateral sclerosis (ALS) is characterized by selective and progressive neurodegenerative changes in motor neural networks. Given the system complexity, including anatomically distributed sites of degeneration from the motor cortex to the spinal cord and chronic pro-inflammatory conditions, a cell-based therapeutic strategy could be an alternative approach to treating ALS. Lessons from previous mesenchymal stromal/stem cell (MSC) trials in ALS realized the importance of 3 aspects in current and future MSC therapy, including the preparation of MSCs, administration routes and methods, and recipient-related factors. This review briefly describes the current status and future prerequisites for an optimal strategy using bone-marrow-originated MSCs to treat ALS. We suggest mandatory factors in the optimized therapeutic strategy focused on advanced therapy medicinal products produced according to Good Manufacturing Practice, an optimal administration method, the selection of proper patients, and the importance of biomarkers.

Unraveling the Heterogeneity of ALS-A Call to Redefine Patient Stratification for Better Outcomes in Clinical Trials

Despite tremendous efforts in basic research and a growing number of clinical trials aiming to find effective treatments, amyotrophic lateral sclerosis (ALS) remains an incurable disease. One possible reason for the lack of effective causative treatment options is that ALS may not be a single disease entity but rather may represent a clinical syndrome, with diverse genetic and molecular causes, histopathological alterations, and subsequent clinical presentations contributing to its complexity and variability among individuals. Defining a way to subcluster ALS patients is becoming a central endeavor in the field. Identifying specific clusters and applying them in clinical trials could enable the development of more effective treatments. This review aims to summarize the available data on heterogeneity in ALS with regard to various aspects, e.g., clinical, genetic, and molecular.

Brain-Gut-Microbiota Axis in Amyotrophic Lateral Sclerosis: A Historical Overview and Future Directions

Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease which is strongly associated with age. The incidence of ALS increases from the age of 40 and peaks between the ages of 65 and 70. Most patients die of respiratory muscle paralysis or lung infections within three to five years of the appearance of symptoms, dealing a huge blow to patients and their families. With aging populations, improved diagnostic methods and changes in reporting criteria, the incidence of ALS is likely to show an upward trend in the coming decades. Despite extensive researches have been done, the cause and pathogenesis of ALS remains unclear. In recent decades, large quantities of studies focusing on gut microbiota have shown that gut microbiota and its metabolites seem to change the evolvement of ALS through the brain-gut-microbiota axis, and in turn, the progression of ALS will exacerbate the imbalance of gut microbiota, thereby forming a vicious cycle. This suggests that further exploration and identification of the function of gut microbiota in ALS may be crucial to break the bottleneck in the diagnosis and treatment of this disease. Hence, the current review summarizes and discusses the latest research advancement and future directions of ALS and brain-gut-microbiota axis, so as to help relevant researchers gain correlative information instantly.

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.

Pathomechanistic Networks of Motor System Injury in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is the most common, adult-onset, progressive motor neurodegenerative disorder that results in death within 3 years of the clinical diagnosis. Due to the clinicopathological heterogeneity, any reliable biomarkers for diagnosis or prognosis of ALS have not been identified till date. Moreover, the only three clinically approved treatments are not uniformly effective in slowing the disease progression. Over the last 15 years, there has been a rapid advancement in research on the complex pathomechanistic landscape of ALS that has opened up new avenues for successful clinical translation of targeted therapeutics. Multiple studies suggest that the age-dependent interaction of risk-associated genes with environmental factors and endogenous modifiers is critical to the multi-step process of ALS pathogenesis. In this review, we provide an updated discussion on the dysregulated cross-talk between intracellular homeostasis processes, the unique molecular networks across selectively vulnerable cell types, and the multisystemic nature of ALS pathomechanisms. Importantly, this work highlights the alteration in epigenetic and epitranscriptomic landscape due to gene-environment interactions, which have been largely overlooked in the context of ALS pathology. Finally, we suggest that precision medicine research in ALS will be largely benefitted from the stratification of patient groups based on the clinical phenotype, onset and progression, genome, exposome, and metabolic identities.

SerpinA1 levels in amyotrophic lateral sclerosis patients: An exploratory study

BACKGROUND

SerpinA1, a serine protease inhibitor, is involved in the modulation of microglial-mediated inflammation in neurodegenerative diseases. We explored SerpinA1 levels in cerebrospinal fluid (CSF) and serum of amyotrophic lateral sclerosis (ALS) patients to understand its potential role in the pathogenesis of the disease.

METHODS

SerpinA1, neurofilament light (NfL) and heavy (NfH) chain, and chitinase-3-like protein-1 (CHI3L1) were determined in CSF and serum of ALS patients (n = 110) and healthy controls (n = 10) (automated next-generation ELISA), and correlated with clinical parameters, after identifying three classes of progressors (fast, intermediate, slow). Biomarker levels were analyzed for diagnostic power and association with progression and survival.

RESULTS

SerpinA1serum was significantly decreased in ALS (median: 1032 μg/mL) compared with controls (1343 μg/mL) (p = 0.02). SerpinA1CSF was elevated only in fast progressors (8.6 μg/mL) compared with slow (4.43 μg/mL, p = 0.01) and intermediate (4.42 μg/mL, p = 0.03) progressors. Moreover, SerpinA1CSF correlated with neurofilament and CHI3L1 levels in CSF. Contrarily to SerpinA1CSF , neurofilament and CHI3L1 concentrations in CSF correlated with measures of disease progression in ALS, while SerpinA1serum mildly related with time to generalization (rho = 0.20, p = 0.04). In multivariate analysis, the ratio between serum and CSF SerpinA1 (SerpinA1 ratio) and NfHCSF were independently associated with survival.

CONCLUSIONS

Higher SerpinA1CSF levels are found in fast progressors, suggesting SerpinA1 is a component of the neuroinflammatory mechanisms acting upon fast-progressing forms of ALS. Both neurofilaments or CHI3L1CSF levels outperformed SerpinA1 at predicting disease progression rate in our cohort, and so the prognostic value of SerpinA1 alone as a measure remains inconclusive.

Immunology of amyotrophic lateral sclerosis - role of the innate and adaptive immunity

This review aims to summarize the latest evidence about the role of innate and adaptive immunity in Amyotrophic Lateral Sclerosis (ALS). ALS is a devastating neurodegenerative disease affecting upper and lower motor neurons, which involves essential cells of the immune system that play a basic role in innate or adaptive immunity, that can be neurotoxic or neuroprotective for neurons. However, distinguishing between the sole neurotoxic or neuroprotective function of certain cells such as astrocytes can be challenging due to intricate nature of these cells, the complexity of the microenvironment and the contextual factors. In this review, in regard to innate immunity we focus on the involvement of monocytes/macrophages, microglia, the complement, NK cells, neutrophils, mast cells, and astrocytes, while regarding adaptive immunity, in addition to humoral immunity the most important features and roles of T and B cells are highlighted, specifically different subsets of CD4+ as well as CD8+ T cells. The role of autoantibodies and cytokines is also discussed in distinct sections of this review.

Immunological drivers of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS), a devastating motor neuron disease involving complex genetic and environmental factors, is associated with neuroinflammation. Preclinical and clinical studies support immune system involvement in ALS pathogenesis, thereby spurring investigations into potential pathogenic mechanisms, immune response biomarkers, and ALS therapeutics.

Neutrophils Are Associated with Higher Risk of Incident Amyotrophic Lateral Sclerosis in a BMI- and Age-Dependent Manner

OBJECTIVE

Peripheral immune markers have been associated with the progression and prognosis of amyotrophic lateral sclerosis (ALS). However, whether dysregulation of peripheral immunity is a risk factor for ALS or a consequence of motor neuron degeneration has not yet been clarified. We aimed to identify longitudinal associations between prediagnostic peripheral immunity and the risk of incident ALS.

METHODS

A total of 345,000 individuals from the UK Biobank between 2006 and 2010 were included at the baseline. The counts of peripheral immune markers (neutrophils, lymphocytes, monocytes, platelets, and CRP) and its derived metrics (neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio [PLR], lymphocyte-to-monocyte ratio [LMR], and systemic immune-inflammation index [SII]) were analyzed in relation to the following incident ALS by Cox proportional hazard models. Subgroup and interaction analyses were performed to explore the covariates of these relationships further.

RESULTS

After adjusting for all covariates, the multivariate analysis showed that high neutrophil counts and their derived metrics (NLR and SII) were associated with an increased risk of ALS incidence (per SD increment hazard ratio [HR] = 1.15, 95% confidence interval [CI] = 1.02-1.29 for neutrophils; HR = 1.15, 95% CI = 1.03-1.28 for NLR; and HR = 1.17, 95% CI = 1.05-1.30 for SII). Subgroup and interaction analyses revealed that body mass index (BMI) and age had specific effects on this association. In participants with BMI ≥ 25 or age < 65 years, higher neutrophil counts, and their metrics increased the risk of incident ALS; however, in participants with BMI < 25 or age ≥ 65 years, neutrophils had no effect on incident ALS.

INTERPRETATION

Our study provides evidence that increased neutrophil levels and neutrophil-derived metrics (NLR and SII) are associated with an increased risk of developing ALS. ANN NEUROL 2023;94:942-954.

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.

Insights on the Multifaceted Roles of Wild-Type and Mutated Superoxide Dismutase 1 in Amyotrophic Lateral Sclerosis Pathogenesis

Amyotrophic Lateral Sclerosis (ALS) is a progressive motor neurodegenerative disease. Cell damage in ALS is the result of many different, largely unknown, pathogenetic mechanisms. Astrocytes and microglial cells play a critical role also for their ability to enhance a deranged inflammatory response. Excitotoxicity, due to excessive glutamate levels and increased intracellular Ca2+ concentration, has also been proposed to play a key role in ALS pathogenesis/progression. Reactive Oxygen Species (ROS) behave as key second messengers for multiple receptor/ligand interactions. ROS-dependent regulatory networks are usually mediated by peroxides. Superoxide Dismutase 1 (SOD1) physiologically mediates intracellular peroxide generation. About 10% of ALS subjects show a familial disease associated with different gain-of-function SOD1 mutations. The occurrence of sporadic ALS, not clearly associated with SOD1 defects, has been also described. SOD1-dependent pathways have been involved in neuron functional network as well as in immune-response regulation. Both, neuron depolarization and antigen-dependent T-cell activation mediate SOD1 exocytosis, inducing increased interaction of the enzyme with a complex molecular network involved in the regulation of neuron functional activity and immune response. Here, alteration of SOD1-dependent pathways mediating increased intracellular Ca2+ levels, altered mitochondria functions and defective inflammatory process regulation have been proposed to be relevant for ALS pathogenesis/progression.

Peripheral immune system modulates Purkinje cell degeneration in Niemann-Pick disease type C1

Niemann-Pick disease type C1 (NPC1) is a fatal lysosomal storage disorder characterized by progressive neuronal degeneration. Its key pathogenic events remain largely unknown. We have, herein, found that neonatal BM-derived cell transplantation can ameliorate Purkinje cell degeneration in NPC1 mice. We subsequently addressed the impact of the peripheral immune system on the neuropathogenesis observed in NPC1 mice. The depletion of mature lymphocytes promoted NPC1 phenotypes, thereby suggesting a neuroprotective effect of lymphocytes. Moreover, the peripheral infusion of CD4-positive cells (specifically, of regulatory T cells) from normal healthy donor ameliorated the cerebellar ataxic phenotype and enhanced the survival of Purkinje cells. Conversely, the depletion of regulatory T cells enhanced the onset of the neurological phenotype. On the other hand, circulating inflammatory monocytes were found to be involved in the progression of Purkinje cell degeneration, whereas the depletion of resident microglia had little effect. Our findings reveal a novel role of the adaptive and the innate immune systems in NPC1 neuropathology.

Neuroinflammatory Pathways in the ALS-FTD Continuum: A Focus on Genetic Variants

Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal dementia (FDT) are progressive neurodegenerative disorders that, in several cases, overlap in clinical presentation, and genetic and pathological disease mechanisms. About 10-15% of ALS cases and up to 40% of FTD are familial, usually with dominant traits. ALS and FTD, in several cases, share common gene mutations, such as in C9ORF72, TARDBP, SQSTM-1, FUS, VCP, CHCHD10, and TBK-1. Also, several mechanisms are involved in ALS and FTD pathogenesis, such as protein misfolding, oxidative stress, and impaired axonal transport. In addition, neuroinflammation and neuroinflammatory cells, such as astrocytes, oligodendrocytes, microglia, and lymphocytes and, overall, the cellular microenvironment, have been proposed as pivotal players in the pathogenesis the ALS-FTD spectrum disorders. This review overviews the current evidence regarding neuroinflammatory markers in the ALS/FTD continuum, focusing on the neuroinflammatory pathways involved in the genetic cases, moving from post-mortem reports to in vivo biofluid and neuroimaging data. We further discuss the potential link between genetic and autoimmune disorders and potential therapeutic implications.

Role of NCKAP1 in the Defective Phagocytic Function of Microglia-Like Cells Derived from Rapidly Progressing Sporadic ALS

Microglia plays a key role in determining the progression of amyotrophic lateral sclerosis (ALS), yet their precise role in ALS has not been identified in humans. This study aimed to identify a key factor related to the functional characteristics of microglia in rapidly progressing sporadic ALS patients using the induced microglia model, although it is not identical to brain resident microglia. After confirming that microglia-like cells (iMGs) induced by human monocytes could recapitulate the main signatures of brain microglia, step-by-step comparative studies were conducted to delineate functional differences using iMGs from patients with slowly progressive ALS [ALS(S), n = 14] versus rapidly progressive ALS [ALS(R), n = 15]. Despite an absence of significant differences in the expression of microglial homeostatic genes, ALS(R)-iMGs preferentially showed defective phagocytosis and an exaggerated pro-inflammatory response to LPS stimuli compared to ALS(S)-iMGs. Transcriptome analysis revealed that the perturbed phagocytosis seen in ALS(R)-iMGs was closely associated with decreased NCKAP1 (NCK-associated protein 1)-mediated abnormal actin polymerization. NCKAP1 overexpression was sufficient to rescue impaired phagocytosis in ALS(R)-iMGs. Post-hoc analysis indicated that decreased NCKAP1 expression in iMGs was correlated with the progression of ALS. Our data suggest that microglial NCKAP1 may be an alternative therapeutic target in rapidly progressive sporadic ALS.

Microglial crosstalk with astrocytes and immune cells in amyotrophic lateral sclerosis

In recent years, biomedical research efforts aimed to unravel the mechanisms involved in motor neuron death that occurs in amyotrophic lateral sclerosis (ALS). While the main causes of disease progression were first sought in the motor neurons, more recent studies highlight the gliocentric theory demonstrating the pivotal role of microglia and astrocyte, but also of infiltrating immune cells, in the pathological processes that take place in the central nervous system microenvironment. From this point of view, microglia-astrocytes-lymphocytes crosstalk is fundamental to shape the microenvironment toward a pro-inflammatory one, enhancing neuronal damage. In this review, we dissect the current state-of-the-art knowledge of the microglial dialogue with other cell populations as one of the principal hallmarks of ALS progression. Particularly, we deeply investigate the microglia crosstalk with astrocytes and immune cells reporting in vitro and in vivo studies related to ALS mouse models and human patients. At last, we highlight the current experimental therapeutic approaches that aim to modulate microglial phenotype to revert the microenvironment, thus counteracting ALS progression.

Neuroimmune characterization of optineurin insufficiency mouse model during ageing

Optineurin is a multifunctional polyubiquitin-binding protein implicated in inflammatory signalling. Optineurin mutations are associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), neurodegenerative diseases characterised by neuronal loss, neuroinflammation, and peripheral immune disbalance. However, the pathogenic role of optineurin mutations is unclear. We previously observed no phenotype in the unmanipulated young optineurin insufficiency mice (Optn^470T), designed to mimic ALS/FTD-linked truncations deficient in polyubiquitin binding. The purpose of this study was to investigate whether ageing would trigger neurodegeneration. We performed a neurological, neuropathological, and immunological characterization of ageing wild-type (WT) and Optn^470T mice. No motor or cognitive differences were detected between the genotypes. Neuropathological analyses demonstrated signs of ageing including lipofuscin accumulation and microglial activation in WT mice. However, this was not worsened in Optn^470T mice, and they did not exhibit TAR DNA-binding protein 43 (TDP-43) aggregation or neuronal loss. Spleen immunophenotyping uncovered T cell immunosenescence at two years but without notable differences between the WT and Optn^470T mice. Conventional dendritic cells (cDC) and macrophages exhibited increased expression of activation markers in two-year-old Optn^470T males but not females, although the numbers of innate immune cells were similar between genotypes. Altogether, a combination of optineurin insufficiency and ageing did not induce ALS/FTD-like immune imbalance and neuropathology in mice.

Current State and Future Directions in the Therapy of ALS

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder affecting upper and lower motor neurons, with death resulting mainly from respiratory failure three to five years after symptom onset. As the exact underlying causative pathological pathway is unclear and potentially diverse, finding a suitable therapy to slow down or possibly stop disease progression remains challenging. Varying by country Riluzole, Edaravone, and Sodium phenylbutyrate/Taurursodiol are the only drugs currently approved in ALS treatment for their moderate effect on disease progression. Even though curative treatment options, able to prevent or stop disease progression, are still unknown, recent breakthroughs, especially in the field of targeting genetic disease forms, raise hope for improved care and therapy for ALS patients. In this review, we aim to summarize the current state of ALS therapy, including medication as well as supportive therapy, and discuss the ongoing developments and prospects in the field. Furthermore, we highlight the rationale behind the intense research on biomarkers and genetic testing as a feasible way to improve the classification of ALS patients towards personalized medicine.

The contribution of the peripheral immune system to neurodegeneration

Microglial cells are the major immune cells of the central nervous system (CNS), and directly react to neurodegeneration, but other immune cell types are also able to react to pathology and can modify the course of neurodegenerative processes. These mainly include monocytes/macrophages and lymphocytes. While these peripheral immune cells were initially considered to act only after infiltrating the CNS, recent evidence suggests that some of them can also act directly from the periphery. We will review the existing and emerging evidence for a role of peripheral immune cells in neurodegenerative diseases, both with and without CNS infiltration. Our focus will be on amyotrophic lateral sclerosis, but we will also compare to Alzheimer's disease and Parkinson's disease to highlight similarities or differences. Peripheral immune cells are easily accessible, and therefore may be an attractive therapeutic target for neurodegenerative diseases. Thus, understanding how these peripheral immune cells communicate with the CNS deserves deeper investigation.

Biofluid Biomarkers in the Prognosis of Amyotrophic Lateral Sclerosis: Recent Developments and Therapeutic Applications

Amyotrophic lateral sclerosis is a neurodegenerative disease characterized by the degeneration of motor neurons for which effective therapies are lacking. One of the most explored areas of research in ALS is the discovery and validation of biomarkers that can be applied to clinical practice and incorporated into the development of innovative therapies. The study of biomarkers requires an adequate theoretical and operational framework, highlighting the "fit-for-purpose" concept and distinguishing different types of biomarkers based on common terminology. In this review, we aim to discuss the current status of fluid-based prognostic and predictive biomarkers in ALS, with particular emphasis on those that are the most promising ones for clinical trial design and routine clinical practice. Neurofilaments in cerebrospinal fluid and blood are the main prognostic and pharmacodynamic biomarkers. Furthermore, several candidates exist covering various pathological aspects of the disease, such as immune, metabolic and muscle damage markers. Urine has been studied less often and should be explored for its possible advantages. New advances in the knowledge of cryptic exons introduce the possibility of discovering new biomarkers. Collaborative efforts, prospective studies and standardized procedures are needed to validate candidate biomarkers. A combined biomarkers panel can provide a more detailed disease status.

Mutant and curli-producing E. coli enhance the disease phenotype in a hSOD1-G93A mouse model of ALS

The gut microbiome is a potential non-genetic contributing factor for Amyotrophic Lateral Sclerosis. Differences in gut microbial communities have been detected between ALS subjects and healthy controls, including an increase in Escherichia coli in ALS subjects. E. coli and other gram-negative bacteria produce curli proteins, which are functional bacterial amyloids. We examined whether long-term curli overexposure in the gut can exacerbate the development and progression of ALS. We utilized the slow-developing hSOD1-G93A mouse model of ALS with their C57BL/6J WT littermate controls, including males and females, with a total of 91 animals. These mice were on a normal chow diet and fed curli-producing or curli-nonproducing (mutant) E. coli in applesauce (vehicle) 3 times/week, from 1 through 7 months of age. Male hSOD1 mice demonstrated gradual slowing in running speed month 4 onwards, while females exhibited no signs of locomotive impairment even at 7 months of age. Around the same time, male hSOD1 mice showed a gradual increase in frequency of peripheral CD19⁺ B cells. Among the male hSOD1 group, chronic gut exposure to curli-producing E. coli led to significant shifts in α- and β-diversities. Curli-exposed males showed suppression of immune responses in circulation, but an increase in markers of inflammation, autophagy and protein turnover in skeletal muscle. Some of these markers were also changed in mutant E. coli-exposed mice, including astrogliosis in the brainstem and demyelination in the lumbar spinal cord. Overall, chronic overexposure to a commensal bacteria like E. coli led to distant organ pathology in our model, without the presence of a leaky gut at 6 months. Mechanisms underlying gut-distant organ communication are of tremendous interest to all disciplines.

Telomerase reverse transcriptase and neurodegenerative diseases

Neurodegenerative diseases (NDs) are chronic conditions that result in progressive damage to the nervous system, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and Amyotrophic lateral sclerosis (ALS). Age is a major risk factor for NDs. Telomere shortening is a biological marker of cellular aging, and telomerase reverse transcriptase (TERT) has been shown to slow down this process by maintaining telomere length. The blood-brain barrier (BBB) makes the brain a unique immune organ, and while the number of T cells present in the central nervous system is limited, they play an important role in NDs. Research suggests that NDs can be influenced by modulating peripheral T cell immune responses, and that TERT may play a significant role in T cell senescence and NDs. This review focuses on the current state of research on TERT in NDs and explores the potential connections between TERT, T cells, and NDs. Further studies on aging and telomeres may provide valuable insights for developing therapeutic strategies for age-related diseases.

The potential for treg-enhancing therapies in nervous system pathologies

While inflammation may not be the cause of disease, it is well known that it contributes to disease pathogenesis across a multitude of peripheral and central nervous system disorders. Chronic and overactive inflammation due to an effector T-cell-mediated aberrant immune response ultimately leads to tissue damage and neuronal cell death. To counteract peripheral and neuroinflammatory responses, research is being focused on regulatory T cell enhancement as a therapeutic target. Regulatory T cells are an immunosuppressive subpopulation of CD4+ T helper cells essential for maintaining immune homeostasis. The cells play pivotal roles in suppressing immune responses to maintain immune tolerance. In so doing, they control T cell proliferation and pro-inflammatory cytokine production curtailing autoimmunity and inflammation. For nervous system pathologies, Treg are known to affect the onset and tempo of neural injuries. To this end, we review recent findings supporting Treg's role in disease, as well as serving as a therapeutic agent in multiple sclerosis, myasthenia gravis, Guillain-Barre syndrome, Parkinson's and Alzheimer's diseases, and amyotrophic lateral sclerosis. An ever-broader role for Treg in the control of neurologic disease has been shown for traumatic brain injury, stroke, neurotrophic pain, epilepsy, and psychiatric disorders. To such ends, this review serves to examine the role played by Tregs in nervous system diseases with a focus on harnessing their functional therapeutic role(s).