Circulating CD56dim NK cells expressing perforin are increased in progressive multiple sclerosis

Disease Aggravation With Age in an Experimental Model of Multiple Sclerosis: Role of Immunosenescence

The onset of multiple sclerosis (MS) in older individuals correlates with a higher risk of developing primary progressive MS, faster progression to secondary progressive MS, and increased disability accumulation. This phenomenon can be related to age-related changes in the immune system: with age, the immune system undergoes a process called immunosenescence, characterized by a decline in the function of both the innate and adaptive immune responses. This decline can lead to a decreased ability to control inflammation and repair damaged tissue. Additionally, older individuals often experience a shift toward a more pro-inflammatory state, known as inflammaging, which can exacerbate the progression of neurodegenerative diseases like MS. Therefore, age-related alterations in the immune system could be responsible for the difference in the phenotype of MS observed in older and younger patients. In this study, we investigated the effects of age on the immunopathogenesis of experimental autoimmune encephalomyelitis (EAE). Our findings indicate that EAE is more severe in aged mice due to a more inflammatory and neurodegenerative environment in the central nervous system. Age-related changes predominantly affect adaptive immunity, characterized by altered T cell ratios, a pro-inflammatory Th1 response, increased regulatory T cells, exhaustion of T cells, altered B cell antigen presentation, and reduced NK cell maturation and cytotoxicity. Transcriptomic analysis reveals that fewer pathways and transcription factors are activated with age in EAE. These findings allow us to identify potential therapeutic targets specific to elderly MS patients and work on their development in the future.

Natural killer cells in multiple sclerosis: foe or friends?

Multiple sclerosis (MS) is an immune-mediated disorder involving the central nervous system (CNS), in which demyelination is caused. The initiation and progression of MS is thought to depend largely on CD4+ T lymphocytes, yet new data has emphasized the involvement of the innate immune system in the MS disease responses. Generally, several types of immune cells play a part, with natural killer (NK) cells being essential. Different subsets of natural killer cells function differently within the course of an autoimmune disease, such as MS. There are mainly two types of natural killers in humans: immature CD56 bright CD16- and mature CD56 dim CD16+ natural killers, together with their respective subtypes. Factors from natural killers expand the T cell population and control the process by which native CD4+ T cells differentiate into Th1 or Th2 lymphocytes, which affect autoimmune responses. Natural killer subsets CD56 bright and CD56 dim may have differing roles in MS development. The impact of these NK cell subsets is influenced by factors such as Granzymes, genetics, infections, TLR, and HSP. We reviewed and evaluated the relationship between natural killer cells and MS.

Sportizumab - Multimodal progressive exercise over 10 weeks decreases Th17 frequency and CD49d expression on CD8+ T cells in relapsing-remitting multiple sclerosis: A randomized controlled trial

BACKGROUND

Multiple Sclerosis (MS) represents a neuroinflammatory autoimmune disease characterized by the predominance of circulating T cell subsets with proinflammatory characteristics and increased central nervous system (CNS)-homing potential. Substantial evidence confirms various beneficial effects of chronic exercise interventions in MS, but it is unknown how long-term multi-modal intense exercise affects MS-associated lymphocytes that are commonly targeted by medication in persons with relapsing remitting MS (pwRRMS).

METHODS

A total of 45 participants with defined RRMS were randomized to either the exercise (n = 22) or passive waitlist-control group (n = 23). A 10-week intervention consisting of progressive resistance and strength-endurance exercises was applied (3x/week à 60 min). Blood was drawn before (T1) and after (T2) the intervention period. Flow cytometry was used for phenotyping lymphocyte subsets.

RESULTS

Relative protein expression of CD49d within CD8+ T cells, quantified via mean fluorescence intensity (MFI), is significantly associated with the Expanded Disability Status Scale (p = 0.007, r = 0.440), decreased in the exercise group (p = 0.001) only, and was significantly lower in the exercise compared to the control group at T2 (p < 0.001). T helper (Th) 17 cell frequency decreased only in the exercise group (p < 0.001). CD8+CD20+ T cell frequency was significantly lower in the exercise compared to the control group at T2 (p = 0.003), without showing significant time effects.

CONCLUSION

The 10-week multimodal exercise intervention mainly affected circulating T cells harboring a pathophysiological phenotype in MS. The findings of a decreased frequency of pathogenic Th17 cells and the reduced CNS-homing potential of CD8+ T cells, indicated by reduced CD49d MFI, substantiate the positive effects of exercise on cellular biomarkers involved in disease activity and progression in MS. To confirm exercise-mediated beneficial effects on both disease domains, clinical endpoints (i.e., relapse rate, lesion formation, EDSS score) should be assessed together with these cellular and molecular markers in studies with a larger sample size and a duration of six to twelve months or longer.

Distorted frequency and functionality of natural killer cells in pemphigus vulgaris: A potential therapeutic target

Pemphigus vulgaris (PV) is a rare autoimmune disorder where autoantibodies target the desmosomal proteins resulting in blistering of oral mucosa and skin. While the pathogenesis of PV is mainly mediated by the adaptive immune system, key players of innate immunity are also emerging. This study outlines the phenotypic as well as functional attributes of NK cells in PV. Through in-depth analysis using flow cytometry we identified an increase in the frequency of CD56+ CD3- NK cells and their subtypes in periphery. Along with this there is an increased frequency of IFNγ+ CD56bright CD16dim NK cells. mRNA expression of sorted NK cells for differentially expressed genes, particularly key transcription factors such as T-bet and EOMES, as well as surface receptors like NKG2D and KIR2D, and the cytokine IFNγ, displayed significant upregulation. A significant activation of NK cells was seen in the disease state. The levels of perforin and IFNγ were significantly elevated in the culture supernatants of patients. Additionally, a significantly higher cytotoxicity of NK cells in PV was observed. In lesioned tissues of PV, NK related markers were significantly increased. Lastly, we observed NK cells using confocal microscopy in the tissue biopsies of patients which showed significant infiltration of CD56+ CD3- NK cells at the lesional sites. This study aimed to shed light on the pivotal role of NK cells in the immunopathology of PV, offering a thorough understanding of their behaviour and changes in expression which might help in contributing to the development of novel therapeutics.

The ratio of circulating CD56dim NK cells to follicular T helper cells as a promising predictor for disease activity of relapsing-remitting multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system primarily mediated by CD4+ T helper cells. This study investigated the dynamic changes of natural killer (NK) cells and follicular T helper (Tfh) cells and their associations in relapsing-remitting MS patients. The findings revealed inverse relationships between NK cells and CD4+ T cells or Tfh cells. Specifically, CD56dim NK cells, not CD56bright NK cells, were negatively correlated with CD4+ T cells and Tfh cells. However, no significant correlations were found between NK cells and sNfL levels or EDSS scores. The ratio of CD56dim NK cells to circulating Tfh (cTfh) cells demonstrated superior discriminatory ability in distinguishing relapsing MS patients from healthy controls (HCs) and remitting patients, as determined by receiver operating characteristic (ROC) analysis. Following treatment with immunosuppressants or disease-modifying therapies (DMTs), a significant increase in the CD56dim NK/cTfh ratio was observed. These findings suggest that the CD56dim NK/cTfh ratio holds promise as a prognostic indicator for clinical relapse and treatment response in MS.

Therapeutic potential of natural killer cells in neuroimmunological diseases

Natural killer (NK) cells, a major component of the innate immune system, have prominent immunoregulatory, antitumor proliferation, and antiviral activities. NK cells act as a double-edged sword with therapeutic potential in neurological autoimmunity. Emerging evidence has identified NK cells are involved in the development and progression of neuroimmunological diseases such as multiple sclerosis, neuromyelitis optica spectrum disorders, autoimmune encephalitis, Guillain-Barré Syndrome, chronic inflammatory demyelinating polyneuropathy, myasthenia gravis, and idiopathic inflammatory myopathy. However, the regulatory mechanisms and functional roles of NK cells are highly variable in different clinical states of neuroimmunological diseases and need to be further determined. In this review, we summarize the evidence for the heterogenic involvement of NK cells in the above conditions. Further, we describe cutting-edge NK-cell-based immunotherapy for neuroimmunological diseases in preclinical and clinical development and highlight challenges that must be overcome to fully realize the therapeutic potential of NK cells.

Multiple sclerosis endophenotypes identified by high-dimensional blood signatures are associated with distinct disease trajectories

One of the biggest challenges in managing multiple sclerosis is the heterogeneity of clinical manifestations and progression trajectories. It still remains to be elucidated whether this heterogeneity is reflected by discrete immune signatures in the blood as a surrogate of disease pathophysiology. Accordingly, individualized treatment selection based on immunobiological principles is still not feasible. Using two independent multicentric longitudinal cohorts of patients with early multiple sclerosis (n = 309 discovery and n = 232 validation), we were able to identify three distinct peripheral blood immunological endophenotypes by a combination of high-dimensional flow cytometry and serum proteomics, followed by unsupervised clustering. Longitudinal clinical and paraclinical follow-up data collected for the cohorts revealed that these endophenotypes were associated with disease trajectories of inflammation versus early structural damage. Investigating the capacity of immunotherapies to normalize endophenotype-specific immune signatures revealed discrete effect sizes as illustrated by the limited effect of interferon-β on endophenotype 3-related immune signatures. Accordingly, patients who fell into endophenotype 3 subsequently treated with interferon-β exhibited higher disease progression and MRI activity over a 4-year follow-up compared with treatment with other therapies. We therefore propose that ascertaining a patient's blood immune signature before immunomodulatory treatment initiation may facilitate prediction of clinical disease trajectories and enable personalized treatment decisions based on pathobiological principles.

The role of CD56bright NK cells in neurodegenerative disorders

Emerging evidence suggests a potential role for natural killer (NK) cells in neurodegenerative diseases, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. However, the precise function of NK cells in these diseases remains ambiguous. The existence of two NK cell subsets, CD56bright and CD56dim NK cells, complicates the understanding of the contribution of NK cells in neurodegeneration as their functions within the context of neurodegenerative diseases may differ significantly. CD56bright NK cells are potent cytokine secretors and are considered more immunoregulatory and less terminally differentiated than their mostly cytotoxic CD56dim counterparts. Hence, this review focusses on NK cells, specifically on CD56bright NK cells, and their role in neurodegenerative diseases. Moreover, it explores the mechanisms underlying their ability to enter the central nervous system. By consolidating current knowledge, we aim to provide a comprehensive overview on the role of CD56bright NK cells in neurodegenerative diseases. Elucidating their impact on neurodegeneration may have implications for future therapeutic interventions, potentially ameliorating disease pathogenesis.

The Plasticity of Immune Cell Response Complicates Dissecting the Underlying Pathology of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative autoimmune disease characterized by the destruction of the myelin sheath of the neuronal axon in the central nervous system. Many risk factors, including environmental, epigenetic, genetic, and lifestyle factors, are responsible for the development of MS. It has long been thought that only adaptive immune cells, especially autoreactive T cells, are responsible for the pathophysiology; however, recent evidence has indicated that innate immune cells are also highly involved in disease initiation and progression. Here, we compile the available data regarding the role immune cells play in MS, drawn from both human and animal research. While T and B lymphocytes, chiefly enhance MS pathology, regulatory T cells (Tregs) may serve a more protective role, as can B cells, depending on context and location. Cells chiefly involved in innate immunity, including macrophages, microglia, astrocytes, dendritic cells, natural killer (NK) cells, eosinophils, and mast cells, play varied roles. In addition, there is evidence regarding the involvement of innate-like immune cells, such as γδ T cells, NKT cells, MAIT cells, and innate-like B cells as crucial contributors to MS pathophysiology. It is unclear which of these cell subsets are involved in the onset or progression of disease or in protective mechanisms due to their plastic nature, which can change their properties and functions depending on microenvironmental exposure and the response of neural networks in damage control. This highlights the need for a multipronged approach, combining stringently designed clinical data with carefully controlled in vitro and in vivo research findings, to identify the underlying mechanisms so that more effective therapeutics can be developed.

The role of miRNAs in multiple sclerosis pathogenesis, diagnosis, and therapeutic resistance

In recent years, microRNAs (miRNAs) have gained increased attention from researchers around the globe. Although it is twenty nucleotides long, it can modulate several gene targets simultaneously. Their mal expression is a signature of various pathologies, and they provide the foundation to elucidate the molecular mechanisms of each pathology. Among the debilitating central nervous system (CNS) disorders with a growing prevalence globally is the multiple sclerosis (MS). Moreover, the diagnosis of MS is challenging due to the lack of disease-specific biomarkers, and the diagnosis mainly depends on ruling out other disabilities. MS could adversely affect patients' lives through its progression, and only symptomatic treatments are available as therapeutic options, but an exact cure is yet unavailable. Consequently, this review hopes to further the study of the biological features of miRNAs in MS and explore their potential as a therapeutic target.

Teriflunomide modulates both innate and adaptive immune capacities in multiple sclerosis

BACKGROUND

Teriflunomide (TER) (Aubagio™) is an FDA-approved disease-modifying therapy (DMT) for relapsing-remitting multiple sclerosis (RRMS). The mechanism of action of TER is thought to be related to the inhibition of dihydroorotate dehydrogenase (DHODH), a key mitochondrial enzyme in the de novo pyrimidine synthesis pathway required by rapidly dividing lymphocytes. Several large pivotal studies have established the efficacy and safety of TER in patients with RRMS. Despite this, little is known about how the adaptive and innate immune cell subsets are affected by the treatment in patients with MS.

METHODS

We recruited 20 patients with RRMS who were newly started on TER and performed multicolor flow cytometry and functional assays on peripheral blood samples. A paired t-test was used for the statistical analysis and comparison.

RESULTS

Our data showed that TER promoted a tolerogenic environment by shifting the balance between activated pathogenic and naïve or immunosuppressive immune cell subsets. In our cohort, TER increased the expression of the immunosuppressive marker CD39 on regulatory T cells (Tregs) while it decreased the expression of the activation marker CXCR3 on CD4⁺ T helper cells. TER treatment also reduced switched memory (sm) B cells while it increased naïve B cells and downregulated the expression of co-stimulatory molecules CD80 and CD86. Additionally, TER reduced the percentage and absolute numbers of natural killer T (NKT) cells, as well as the percentage of natural killer (NK) cells and showed a trend toward reducing the CD56^dim NK pathogenic subset.

CONCLUSION

TER promotes the tolerogenic immune response and suppresses the pathogenic immune response in patients with RRMS.

The immunology of multiple sclerosis

Our incomplete understanding of the causes and pathways involved in the onset and progression of multiple sclerosis (MS) limits our ability to effectively treat this complex neurological disease. Recent studies explore the role of immune cells at different stages of MS and how they interact with cells of the central nervous system (CNS). The findings presented here begin to question the exclusivity of an antigen-specific cause and highlight how seemingly distinct immune cell types can share common functions that drive disease. Innovative techniques further expose new disease-associated immune cell populations and reinforce how environmental context is critical to their phenotype and subsequent role in disease. Importantly, the differentiation of immune cells into a pathogenic state is potentially reversible through therapeutic manipulation. As such, understanding the mechanisms that provide plasticity to causal cell types is likely key to uncoupling these disease processes and may identify novel therapeutic targets that replace the need for cell ablation.

Immune Cell Contributors to the Female Sex Bias in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS) that leads to axonal damage and accumulation of disability. Relapsing-remitting MS (RR-MS) is the most frequent presentation of MS and this form of MS is three times more prevalent in females than in males. This female bias in MS is apparent only after puberty, suggesting a role for sex hormones in this regulation; however, very little is known of the biological mechanisms that underpin the sex difference in MS onset. Experimental autoimmune encephalomyelitis (EAE) is an animal model of RR-MS that presents more severely in females in certain mouse strains and thus has been useful to study sex differences in CNS autoimmunity. Here, we overview the immunopathogenesis of MS and EAE and how immune mechanisms in these diseases differ between a male and female. We further describe how females exhibit more robust myelin-specific T helper (Th) 1 immunity in MS and EAE and how this sex bias in Th cells is conveyed by sex hormone effects on the T cells, antigen presenting cells, regulatory T cells, and innate lymphoid cell populations.

Molecular Mechanisms of Immunosenescene and Inflammaging: Relevance to the Immunopathogenesis and Treatment of Multiple Sclerosis

Aging is characterized, amongst other features, by a complex process of cellular senescence involving both innate and adaptive immunity, called immunosenescence and associated to inflammaging, a low-grade chronic inflammation. Both processes fuel each other and partially explain increasing incidence of cancers, infections, age-related autoimmunity, and vascular disease as well as a reduced response to vaccination. Multiple sclerosis (MS) is a lifelong disease, for which considerable progress in disease-modifying therapies (DMTs) and management has improved long-term survival. However, disability progression, increasing with age and disease duration, remains. Neurologists are now involved in caring for elderly MS patients, with increasing comorbidities. Aging of the immune system therefore has relevant implications for MS pathogenesis, response to DMTs and the risks mediated by these treatments. We propose to review current evidence regarding markers and molecular mechanisms of immunosenescence and their relevance to understanding MS pathogenesis. We will focus on age-related changes in the innate and adaptive immune system in MS and other auto-immune diseases, such as systemic lupus erythematosus and rheumatoid arthritis. The consequences of these immune changes on MS pathology, in interaction with the intrinsic aging process of central nervous system resident cells will be discussed. Finally, the impact of immunosenescence on disease evolution and on the safety and efficacy of current DMTs will be presented.

Fingolimod Therapy in Multiple Sclerosis Leads to the Enrichment of a Subpopulation of Aged NK Cells

Fingolimod is an approved oral treatment for relapsing-remitting multiple sclerosis (RRMS) that modulates agonistically the sphingosin-1-phosphate receptor (S1PR), inhibiting thereby the egress of lymphocytes from the lymph nodes. In this interventional prospective clinical phase IV trial, we longitudinally investigated the impact of fingolimod on frequencies of NK cell subpopulations by flow cytometry in 17 RRMS patients at baseline and 1, 3, 6, and 12 months after treatment initiation. Clinical outcome was assessed by the Expanded Disability Status Scale (EDSS) and annualized relapse rates (ARR). Over the study period, median EDSS remained stable from month 3 to month 12, and ARR decreased compared to ARR in the 24 months prior treatment. Treatment was paralleled by an increased frequency of circulating NK cells, due primarily to an increase in CD56dimCD94low mature NK cells, while the CD56bright fraction and CD127+ innate lymphoid cells (ILCs) decreased over time. An unsupervised clustering algorithm further revealed that a particular fraction of NK cells defined by the expression of CD56dimCD16++KIR+/-NKG2A-CD94-CCR7+/-CX3CR1+/-NKG2C-NKG2D+NKp46-DNAM1++CD127+ increased during treatment. This specific phenotype might reflect a status of aged, fully differentiated, and less functional NK cells. Our study confirms that fingolimod treatment affects both NK cells and ILC. In addition, our study suggests that treatment leads to the enrichment of a specific NK cell subset characterized by an aged phenotype. This might limit the anti-microbial and anti-tumour NK cell activity in fingolimod-treated patients.

Natural killer cells promote the differentiation of follicular helper T cells instead of inducing apoptosis in myasthenia gravis

Recent evidence has shown that natural killer (NK) cells have an immunoregulatory function in the pathogenesis of myasthenia gravis (MG). In this study, the phenotype and function of NK cell subsets in peripheral blood of new-onset MG (N-MG) and stable MG (S-MG) patients were explored. Circulating CD56^dim and CD56^bright NK cells were increased and decreased, respectively, in patients with N-MG and S-MG compared with healthy control (HC). Moreover, all circulating NK cell subsets from N-MG patients showed significantly lower expression of activating receptor NKG2D and production of Interferon (IFN) -γ than that from HC. The killing effects of NK cells on CD4⁺ T cells and Tfh cells were impaired in MG patients, whereas, they promoted the differentiation and activation of Tfh cells. These data indicated that the immune-regulation of NK cells on CD4⁺ T cells and Tfh cells in MG patients was abnormal, which may contribute to the immune-pathological mechanism of MG.

Cytotoxic profile of CD3+CD20+ T cells in progressive multiple sclerosis

Recently, it was shown that highly effective anti-CD20 therapies used for MS patients not only deplete CD20+ B cells, but also a small subset of T cells expressing CD20 surface marker (CD3+CD20+ T cells). Here we demonstrated that, in progressive MS patients, CD3+CD20+ T cells share the ability to express cytotoxic factors such as perforin and serine-protease granzyme-B (GzmB), classically associated with CD8+ T cells functionality. Beyond it, cluster analyses show that a set of activation markers and transcriptional factors related with CD8 effector program are also expressed in CD3+CD20+ T cells. Further characterization of surface and functional markers from CD3+CD20+ T subsets may be helpful for development of new therapeutic strategies mainly for progressive MS patients, as well as for assessing pathophysiological effects of highly effective anti-CD20 therapies.

Effectiveness and safety of dimethyl fumarate in progressive multiple sclerosis

Background

There is limited data analyzing the safety and effectiveness of dimethyl fumarate (DMF) in the progressive multiple sclerosis (PMS) population.

Objective

To analyze the safety and effectiveness of DMF in patients with PMS.

Methods

We used Cox proportional hazards models to compare the time to confirmed worsening and improvement on the Expanded Disability Status Scale (EDSS) and timed 25-foot walk (T25FW) between patients treated with DMF and glatiramer acetate (GA) for at least one year.

Results

We included 46 patients treated with DMF and 42 patients treated with GA. The safety and tolerability of GA and DMF were consistent with established profiles. There was no difference in confirmed EDSS progression. A trend towards reduced T25FW was seen in the DMF compared to GA after adjustment (HR = 0.86; 95% CI:0.37, 1.98; p = 0.72 and HR = 0.60; 95% CI:0.27, 1.34; p = 0.21, respectively).

Conclusion

Dimethyl fumarate showed a trend towards reduction in T25FW but no evidence of clinically significant impact on EDSS. The small sample precluded definitive determination.

A pharmacokinetic and biomarker study of delayed-release dimethyl fumarate in subjects with secondary progressive multiple sclerosis: evaluation of cerebrospinal fluid penetration and the effects on exploratory biomarkers

BACKGROUND

Biomarkers are a useful and reliable measure of disease activity in many fields of medicine. Axonal and glial biomarkers in multiple sclerosis (MS) are being applied more often as technology is improving and becoming increasingly reliable. Nonclinical studies have shown dimethyl fumarate (DMF) to have cytoprotective and anti-inflammatory effects. The purpose of this study is to explore the pharmacokinetics (PK) of DMF (by measuring MMF, the active compound) in serum and cerebrospinal fluid (CSF) as well as relevant biomarker data for patients with secondary progressive MS (pwSPMS) and whether there is objective evidence for neuroprotection in pwSPMS treated with DMF.

METHODS

Sixteen pwSPMS had serum and cerebrospinal fluid (CSF) evaluation for PK studies levels of MMF at various time points after ingestion of DMF. The CSF biomarkers neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), ubiquitin carboxyo-terminal hydrolase isozyme L1 (UCH-L1) and total tau (T-tau) were measured at baseline, week 6 and week 28 after initiating DMF with a starting dose of 120 mg twice daily for 4 weeks, followed by a maintenance dose of 240 mg twice daily. Clinical correlation of these patients with EDSS and MRI at these same time periods were made with the biomarkers. Four normal human volunteers had CSF studies for biomarkers at baseline.

RESULTS

PK data showed CSF MMF concentration 11% of plasma with Tmax of plasma at 5 hr and Tmax of CSF at 7 hr. Biomarker data showed that CS NfL and to a lesser extent, GFAP, but not UCH-L1 nor T-tau showed relevant changes with clinical data. Some pwSPMS receiving DMF showed clinical improvements in Expanded Disability Status Scale (EDSS). Biomarker changes, but not MRI, correlated with clinical measures in this group of pwSPMS over the observation period.

CONCLUSIONS

PK data showed that the Tmax of CSF MMF peaked only 2 hours later than that of plasma with 11% measured in the CSF so that MMF readily crossed the blood brain barrier allowing potential direct penetration into the brain. NfL CSF levels, and to a lesser extent, GFAP CSF levels, showed correlation to disease activity in pwSPMS . These data suggest that DMF may have some benefit in reducing disease activity in pwSPMS if studied for a longer duration and larger well-controlled studies are warranted. DMF was reasonably well tolerated but 3 of the 16 patients did discontinue DMF at 6 weeks due to persistent side effects. NfL appeared to be more clinically relevant biomarker than brain MRI in this this group during the 28-week study period.

CD56bright Natural Killer Cells: A Possible Biomarker of Different Treatments in Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system, which leads, in many cases, to irreversible disability. More than 15 disease-modifying treatments (DMTs) are available for the treatment of MS. Clinical activity or activity at magnetic resonance imaging (MRI) are now used to assess the efficacy of DMTs, but are negative prognostic factors per se. Therefore, a biomarker permitting us to identify patients who respond to treatment before they develop clinical/radiological signs of MS activity would be of high importance. The number of circulating CD56^bright natural killer (NK) cells may be such a biomarker. CD56^bright NK cells are a regulatory immune population belonging to the innate immune system. The number of CD56^bright NK cells increases upon treatment with interferon-beta, alemtuzumab, dimethyl fumarate, after autologous hematopoietic stem cell transplantation, and is higher in those who respond to fingolimod. In some cases, an increased number of CD56^bright NK cells is associated with an increase in their regulatory function. In the current review, we will evaluate the known effect on CD56^bright NK cells of DMTs for MS, and will discuss their possible role as a biomarker for treatment response in MS.

Innate, innate-like and adaptive lymphocytes in the pathogenesis of MS and EAE

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) in which the immune system damages the protective insulation surrounding the nerve fibers that project from neurons. A hallmark of MS and its animal model, experimental autoimmune encephalomyelitis (EAE), is autoimmunity against proteins of the myelin sheath. Most studies in this field have focused on the roles of CD4+ T lymphocytes, which form part of the adaptive immune system as both mediators and regulators in disease pathogenesis. Consequently, the treatments for MS often target the inflammatory CD4+ T-cell responses. However, many other lymphocyte subsets contribute to the pathophysiology of MS and EAE, and these subsets include CD8+ T cells and B cells of the adaptive immune system, lymphocytes of the innate immune system such as natural killer cells, and subsets of innate-like T and B lymphocytes such as γδ T cells, natural killer T cells, and mucosal-associated invariant T cells. Several of these lymphocyte subsets can act as mediators of CNS inflammation, whereas others exhibit immunoregulatory functions in disease. Importantly, the efficacy of some MS treatments might be mediated in part by effects on lymphocytes other than CD4+ T cells. Here we review the contributions of distinct subsets of lymphocytes on the pathogenesis of MS and EAE, with an emphasis on lymphocytes other than CD4+ T cells. A better understanding of the distinct lymphocyte subsets that contribute to the pathophysiology of MS and its experimental models will inform the development of novel therapeutic approaches.

NK cells in autoimmune diseases: Linking innate and adaptive immune responses

The pathogenesis of autoimmunity remains to be fully elucidated, although the contribution of genetic and environmental factors is generally recognized. Despite autoimmune conditions are principally due to T and B lymphocytes, NK cells also appear to play a role in the promotion and/or maintenance of altered adaptive immune responses or in peripheral tolerance mechanisms. Although NK cells are components of the innate immune system, they shows characteristics of the adaptive immune system, such as the expansion of pathogen-specific cells, the generation of long-lasting "memory" cells able to persist upon cognate antigen encounter, and the possibility to induce an increased secondary recall response to re-challenge. Human NK cells are generally identified as CD56+CD3-, conversely CD56+CD3+ cells represent a mixed population of NK-like T (NK T) cells and antigen-experienced T cells showing the up-regulation of several NK cell markers. CD56dim constitute about 90% of NK cells in the peripheral blood, they are mature and involved in cytotoxicity responses; CD56bright instead are more immature, mostly involved in cytokine production, having only a limited role in cytolytic responses, keen to leave the blood vessels as the principal population observed in lymph nodes. NK cells have been identified also in non-lymphoid tissues since, in pathologic conditions, they can quickly reach the target organs. A cross-talk between NK with dendritic cells and T cells is established throughout different receptor-ligand bindings. Several studies support the correlation between NK cell number and/or functional alterations, such as a defective cytotoxic activity and several autoimmune conditions. Among the different autoimmune pathologies and even within the same disease, NK cell function is significantly different either promoting or even protecting against the onset of the autoimmune condition. In this Review, we discuss recent literature supporting the role played by NK cells, as a bridge between innate and adaptive immunity, in the onset of autoimmune diseases.

Western lifestyle and immunopathology of multiple sclerosis

There is increasing evidence for a sudden and unprecedented rise in the incidence of multiple sclerosis (MS) in Westernized countries over the past decades, emphasizing the role of environmental factors. Among many candidates, rapid changes in dietary habits seem to play a role in the pathogenesis of MS. Here, we summarize and discuss the available evidence for the role of dietary nutrients, such as table salt, fatty acids, and flavonoids, in the development and pathogenesis of MS. We also discuss new and emerging risk factors accompanying Western lifestyle, such as shift work, sleep, and circadian disruption.

High Perforin-Positive Cardiac Cell Infiltration and Male Sex Predict Adverse Long-Term Mortality in Patients With Inflammatory Cardiomyopathy

BACKGROUND

The authors analyzed the effects of perforin-dependent infiltration on long-term mortality in patients with inflammatory cardiomyopathy (CMi). We previously demonstrated that left ventricular function deteriorates and progresses to substantial cardiac dysfunction in patients with perforin-positive cardiac cell infiltration.

METHODS AND RESULTS

Between 2003 and 2013, 2389 consecutive patients with clinically suspected CMi who underwent endomyocardial biopsies were enrolled. Endomyocardial biopsies were performed at first admission after exclusion of ischemic or valvular heart disease, and CMi was confirmed in 1717 patients. Follow-up was up to 10.1 years (median 0.47 years; interquartile range, 0.03-2.56 years) and information on vital status was obtained from official resident data files. Multivariable statistical analysis was conducted for all patients with CMi regarding significant predictors of all-cause mortality or need for heart transplantation. Multiple Cox regression analysis revealed perforin above the calculated cutoff point of 2.9 cells/mm² as a strong predictor of impaired survival with a hazard ratio of 1.881 (95% confidence interval, 1.177-3.008; P=0.008), independent of left ventricular function and other myocardial inflammation markers (CD3, macrophage-1 antigen, leukocyte function-associated antigen-1, human leukocyte antigen-1, and intercellular cell adhesion molecule-1). Unexpectedly, male sex emerged as another strong adverse predictor of survival in CMi (hazard ratio, 1.863; confidence interval, 1.096-3.168 [P=0.022]). Whereas left ventricular ejection fraction course is adversely affected by myocardial perforin, multivariate analysis indicates that left ventricular ejection fraction explains only part of the observed overall mortality.

CONCLUSIONS

High perforin-positive cardiac cell infiltration and male sex are independent adverse predictors of long-term mortality in CMi. Furthermore, exact quantification of immunohistochemically detected infiltrates is necessary to assess the prognosis.

Activation of Blood CD3+CD56+CD8+ T Cells during Pregnancy and Multiple Sclerosis

A striking common feature of most autoimmune diseases is their female predominance, with at least twice as common among women than men in relapsing–remitting multiple sclerosis (MS), the prevailing MS clinical form with onset at childbearing age. This fact, together with the protective effect on disease activity during pregnancy, when there are many biological changes including high levels of estrogens and progesterone, puts sex hormones under the spotlight. The role of natural killer (NK) and NKT cells in MS disease beginning and course is still to be elucidated. The uterine NK (uNK) cells are the most predominant immune population in early pregnancy, and the number and function of uNK cells infiltrating the endometrium are sex-hormones’ dependent. However, there is controversy on the role of estrogen or progesterone on circulating NK (CD56^dim and CD56^bright) and NKT cells’ subsets. Here, we show a significantly increased activation of CD3⁺CD56⁺CD8⁺ cells in pregnant MS women (MSP) compared with non-pregnant MS women (NPMS) (p < 0.001) and even with respect to healthy pregnant women (HP, p < 0.001), remaining increased even after delivery. The dynamics of expression of early activation marker CD69 on CD3⁺CD56⁺CD8⁺ cells showed a progressive statistically significant increase along the gestation trimesters (T) and at postpartum (PP) with respect to NPMS (1T: p = 0.018; 2T: p = 0.004; 3T: p < 0.001; PP: p = 0.001). In addition, early activation expression of CD69 on CD3⁺CD56⁺CD8⁺ cells was higher in MSP than HP in the first two trimesters of gestation (p = 0.004 and p = 0.015, respectively). NPMS showed significantly increased cytotoxic/regulatory NK ratio compared with healthy controls (p < 0.001). On the other hand, gender studies showed no differences between MS women and men in NK and CD3⁺CD56⁺CD8⁺ cells’ subsets. Our findings may add on the understanding of the regulatory axis in MS during pregnancy. Further studies on specific CD8⁺ NKT cells function and their role in pregnancy beneficial effects on MS are warranted to move forward more effective MS treatments.

Secondary Progressive Multiple Sclerosis: Definition and Measurement

Secondary progressive multiple sclerosis (SPMS) is diagnosed retrospectively and involves a clinical course characterized by a progressive accumulation of neurological disability, independent of relapses, following an initial relapsing-remitting (RR) phase. Our incomplete understanding of the pathological mechanisms underlying neurodegeneration in multiple sclerosis (MS) may explain why, to date, there is no definitive imaging or laboratory test that is able to inform us when the disease is clearly entering into a progressive phase and why the vast majority of clinical trials testing immunosuppressant and immunomodulating drugs in SPMS patients has so far yielded disappointing or mixed results. Here we discuss the definition(s) of SPMS and how it may vary, outcome measurements (current and emerging) and modern trial design.

IL-21 and IL-21 receptor in the immunopathogenesis of multiple sclerosis

Cytokines are considered important factors in the modulation of various immune responses. Among them, interleukin (IL)-21 is one of the major immune modulators, adjusting various immune responses by affecting various immune cells. It has been suggested that IL-21 may enhance autoimmunity through different mechanisms, such as development and activation of helper T (TH)-17 and follicular helper T (TFH) cells, activation of natural killer (NK) cells, enhancing B-cell differentiation and antibody secretion and suppression of regulatory T (Treg) cells. Moreover, IL-21 has also been suggested to be an inducer of autoimmunity when following treatment of MS patients with some therapeutics such as alemtuzumab. This review will seek to clarify the precise role of IL-21/IL-21R in the pathogenesis of MS and, in its animal model, experimental autoimmune encephalomyelitis (EAE).

Dimethyl fumarate selectively reduces memory T cells in multiple sclerosis patients

BACKGROUND

Dimethyl fumarate (DMF) alters the phenotype of circulating immune cells and causes lymphopenia in a subpopulation of treated multiple sclerosis (MS) patients.

OBJECTIVE

To phenotypically characterize circulating leukocytes in DMF-treated MS patients.

METHODS

Cross-sectional observational comparisons of peripheral blood from DMF-treated MS patients (n = 17 lymphopenic and n = 24 non-lymphopenic), untreated MS patients (n = 17) and healthy controls (n = 23); immunophenotyped using flow cytometry. Longitudinal samples were analyzed for 13 DMF-treated patients.

RESULTS

Lymphopenic DMF-treated patients had significantly fewer circulating CD8(+) and CD4(+) T cells, CD56(dim) natural killer (NK) cells, CD19(+) B cells and plasmacytoid dendritic cells when compared to controls. CXCR3(+) and CCR6(+) expression was disproportionately reduced among CD4(+) T cells, while the proportion of T-regulatory (T-reg) cells was unchanged. DMF did not affect circulating CD56(hi) NKcells, monocytes or myeloid dendritic cells. Whether lymphopenic or not, DMF-treated patients had a lower proportion of circulating central and effector memory T cells and concomitant expansion of naïve T cells compared to the controls.

CONCLUSIONS

DMF shifts the immunophenotypes of circulating T cells, causing a reduction of memory cells and a relative expansion of naïve cells, regardless of the absolute lymphocyte count. This may represent one mechanism of action of the drug. Lymphopenic patients had a disproportionate loss of CD8(+) T-cells, which may affect their immunocompetence.

The contribution of immune and glial cell types in experimental autoimmune encephalomyelitis and multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterised by widespread areas of focal demyelination. Its aetiology and pathogenesis remain unclear despite substantial insights gained through studies of animal models, most notably experimental autoimmune encephalomyelitis (EAE). MS is widely believed to be immune-mediated and pathologically attributable to myelin-specific autoreactive CD4+ T cells. In recent years, MS research has expanded beyond its focus on CD4+ T cells to recognise the contributions of multiple immune and glial cell types to the development, progression, and amelioration of the disease. This review summarises evidence of T and B lymphocyte, natural killer cell, macrophage/microglial, astrocytic, and oligodendroglial involvement in both EAE and MS and the intercommunication and influence of each cell subset in the inflammatory process. Despite important advances in the understanding of the involvement of these cell types in MS, many questions still remain regarding the various subsets within each cell population and their exact contribution to different stages of the disease.