Increased prevalence of lymphoid tissue inducer cells in the cerebrospinal fluid of patients with early multiple sclerosis

Estriol and commensal microflora strains regulate innate lymphoid cells functional activity in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease in which the immune system attacks myelin basic protein of nerve axons. Recently, there has been growing interest in studying the role of a newly described population of immunity cells - innate lymphoid cells (ILCs) in the pathogenesis of the disease. At the same time, it was found that during pregnancy there is a weakening of Th1-mediated autoimmune pathologies manifestations, including MS. In this work, we studied phenotypic characteristics of ILC in MS patients in comparison with healthy donors after 48 h incubation with pregnancy hormone estriol (E3) and commensal microflora cells. To activate ILC, strains of Ecsherichia coli K12 and Lactobacillus plantarum 8R-A3 were used. ILC phenotype was assessed by flow cytometry using monoclonal antibody staining. It has been established that E3 and bacterial factors are able to regulate the maturation of ILC subtypes and their cytokines in different ways. In general, the studied factors influence the phenotypic changes in ILC cells, leading to the transition from one type to another, both in healthy donors and in MS patients.

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.

Circulating CCR6+ILC proportions are lower in multiple sclerosis patients

Objectives

The role of innate lymphoid cells (ILC), particularly helper ILC, in the pathogenesis of multiple sclerosis (MS) is not well understood. Here, we present a comprehensive analysis of peripheral ILC subsets in MS patients prior and after alemtuzumab administration using mass cytometry.

Methods

Circulating ILC were analysed by mass cytometry in MS patients before and after alemtuzumab. These were compared with non-MS controls. MS-related shifts among ILC immunophenotypes were further elucidated by fast interpolation-based t-SNE (Flt-SNE) dimensionality reduction.

Results

Neither natural killer (NK) cells nor helper ILC (ILC1, ILC2 and ILC3) levels were altered following alemtuzumab treatment. However, CD56^bright NK cell expansions were observed in relapsing patients. MS patients prior to alemtuzumab further displayed proportional shifts from ILC1 to ILC2, with MS-associated decreases in CCR6⁺ helper ILC proportions.

Conclusion

CD56^bright NK cells during relapse indicate an immediate response to disease reactivation, while CCR6-related shifts among helper ILC suggest altered ILC migration to the CNS during MS.

Mass cytometry reveals cladribine-induced resets among innate lymphoid cells in multiple sclerosis

Here we present a comprehensive mass cytometry analysis of peripheral innate lymphoid cell (ILC) subsets in relapsing/remitting MS (RRMS) patients prior to and after onset of cladribine tablets (CladT). ILC analysis was conducted on CyTOF data from peripheral blood mononuclear cells (PBMC) of MS patients before, 2 and 6 months after onset of CladT, and non-MS controls. Dimensionality reduction was used for immunophenotyping ILC subsets. CladT reduced all ILC subsets, except for CD56bright NK cells and ILC2. Furthermore, CD38+ NK cell and CCR6+ ILC3 were excluded from CladT-induced immune cell reductions. Post-CladT replenishment by immature ILC was noted by increased CD5+ ILC1 proportions at 2 months, and boosted CD38-CD56bright NK cell numbers at 6 months. CladT induce immune cell depletion among ILC but exclude CD56bright NK cells and ILC2 subsets, as well as CD38+ NK cell and CCR6+ ILC3 immunophenotypes. Post-CladT ILC expansions indicate ILC reconstitution towards a more tolerant immune system phenotype.

Innate Lymphoid Cells - Neglected Players in Multiple Sclerosis

Multiple sclerosis (MS) is a highly debilitating autoimmune disease affecting millions of individuals worldwide. Although classically viewed as T-cell mediated disease, the role of innate lymphoid cells (ILC) such as natural killer (NK) cells and ILC 1-3s has become a focal point as several findings implicate them in the disease pathology. The role of ILCs in MS is still not completely understood as controversial findings have been reported assigning them either a protective or disease-accelerating role. Recent findings in experimental autoimmune encephalomyelitis (EAE) suggest that ILCs infiltrate the central nervous system (CNS), mediate inflammation, and have a disease exacerbating role by influencing the recruitment of autoreactive T-cells. Elucidating the detailed role of ILCs and altered signaling pathways in MS is essential for a more complete picture of the disease pathology and novel therapeutic targets. We here review the current knowledge about ILCs in the development and progression of MS and preclinical models of MS and discuss their potential for therapeutic applications.

Tissue-Dependent Adaptations and Functions of Innate Lymphoid Cells

Tissue-resident immune cells reside in distinct niches across organs, where they contribute to tissue homeostasis and rapidly respond to perturbations in the local microenvironment. Innate lymphoid cells (ILCs) are a family of innate immune cells that regulate immune and tissue homeostasis. Across anatomical locations throughout the body, ILCs adopt tissue-specific fates, differing from circulating ILC populations. Adaptations of ILCs to microenvironmental changes have been documented in several inflammatory contexts, including obesity, asthma, and inflammatory bowel disease. While our understanding of ILC functions within tissues have predominantly been based on mouse studies, development of advanced single cell platforms to study tissue-resident ILCs in humans and emerging patient-based data is providing new insights into this lymphocyte family. Within this review, we discuss current concepts of ILC fate and function, exploring tissue-specific functions of ILCs and their contribution to health and disease across organ systems.

Antigen-presenting innate lymphoid cells orchestrate neuroinflammation

Pro-inflammatory T cells in the central nervous system (CNS) are causally associated with multiple demyelinating and neurodegenerative diseases1-6, but the pathways that control these responses remain unclear. Here we define a population of inflammatory group 3 innate lymphoid cells (ILC3s) that infiltrate the CNS in a mouse model of multiple sclerosis. These ILC3s are derived from the circulation, localize in proximity to infiltrating T cells in the CNS, function as antigen-presenting cells that restimulate myelin-specific T cells, and are increased in individuals with multiple sclerosis. Notably, antigen presentation by inflammatory ILC3s is required to promote T cell responses in the CNS and the development of multiple-sclerosis-like disease in mouse models. By contrast, conventional and tissue-resident ILC3s in the periphery do not appear to contribute to disease induction, but instead limit autoimmune T cell responses and prevent multiple-sclerosis-like disease when experimentally targeted to present myelin antigen. Collectively, our data define a population of inflammatory ILC3s that is essential for directly promoting T-cell-dependent neuroinflammation in the CNS and reveal the potential of harnessing peripheral tissue-resident ILC3s for the prevention of autoimmune disease.

Innate Lymphoid Cells in Tissue Homeostasis and Disease Pathogenesis

Innate lymphoid cells (ILCs) are the most recently discovered family of innate immune cells. ILCs can be categorized into three groups on the basis of the transcription factors that direct their functions and the cytokines they produce. Notably, these functions parallel the effector functions of T lymphocytes. ILCs play a frontline role in host defense and tissue homeostasis by responding rapidly to environmental factors, conducting effector responses in a tissue-specific manner, and interacting with hematopoietic and non-hematopoietic cells throughout the body. Moreover, recent studies reveal that ILCs are involved in development of various inflammatory diseases, such as respiratory diseases, autoimmune diseases, or cancer. In this review, we discuss the recent findings regarding the biology of ILCs in health and inflammatory diseases.

Imbalanced Innate Lymphoid Cells are Associated With Disease Activity and Arthritis Involvement in Patients With Systemic Lupus Erythematosus

Objectives

This study aims to evaluate the frequency and absolute number of circulating innate lymphoid cell (ILC) subsets and their associations with clinical and serological features in systemic lupus erythematosus (SLE).

Patients and methods

We recruited 28 SLE patients (6 males, 22 females; mean age 37.57 years; range, 18 to 56 years) and 13 healthy controls (4 males, 9 females; mean age 32.08 years; range, 19 to 48 years). Circulating ILC subsets were identified by flow cytometry. Associations between all detected cells and SLE disease activity, clinical manifestations, and serum autoantibodies were analyzed.

Results

In this study, significantly higher frequencies of ILC2s and ILC3s, lower frequencies of ILC1s, and higher ILC1/ILC3 and ILC1/ILC2 ratios were observed in SLE patients than in healthy controls. The frequencies and number of ILC3s were positively associated with SLE disease activity index 2000 score and anti-double stranded deoxyribonucleic acid titers in patients with SLE. Decreased ILC1 frequencies, increased ILC3 frequencies, and decreased ILC1/ILC3 and ILC2/ILC3 ratios were observed in patients with arthritis compared to those without arthritis.

Conclusion

Our results indicated biased altered distributions of circulating ILC subsets in SLE. ILC3s were associated with SLE disease activity, and ILC1s, ILC3s, and ILC1/ILC3 and ILC2/ILC3 ratios were associated with SLE accompanied with arthritis. Taken together, these results suggest that ILCs may serve as cellular biomarkers for disease activity and arthritis involvement in SLE.

Daclizumab Therapy for Multiple Sclerosis

Daclizumab is a humanized monoclonal antibody that prevents formation of high-affinity interleukin (IL)-2 receptor (IL-2R). Because activated T cells up-regulate high-affinity IL-2R and IL-2 is used to grow activated T cells in vitro, daclizumab was envisioned to selectively inhibit activated T cells. However, the mechanism of action (MOA) of daclizumab is surprisingly broad and it includes many unanticipated effects on innate immunity. Specifically, daclizumab modulates the development of innate lymphoid cells, leading to expansion of immunoregulatory CD56^bright natural killer (NK) cells. Activated CD56^bright NK cells migrate to the intrathecal compartment in multiple sclerosis (MS) and regulate autoreactive T cells via cytotoxicity. Finally, daclizumab also restricts initial steps of T-cell activation by blocking trans-presentation of IL-2 by dendritic cells to antigen-specific T cells. In conclusion, daclizumab has complex immunomodulatory effects with resultant inhibition of central nervous system inflammation 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.

The role of innate lymphoid cells in health and disease

Innate lymphoid cells (ILCs) are kind of innate immune cells which can be divided into three main subsets according to their cytokine release profile, transcription factors, and surface markers. ILCs affect the initial stages of immunity in response to microbes and participate in immunity, inflammation, and tissue repair. ILCs modulate immunity through resistance to the pathogens and regulation of autoimmune inflammation and metabolic homeostasis. Therefore dysregulation of ILCs may lead to chronic pathologies such as allergies (i.e., asthma), inflammation (i.e., inflammatory bowel disease), and autoimmunity (i.e., psoriasis, atopic dermatitis, rheumatoid arthritis, multiple sclerosis, and ankylosing spondylitis). Regarding the critical role of ILCs in the regulation of immune system, the elucidation of their function in different conditions makes an interesting target for improvement of novel therapeutic approach to modulate an immune response in different disease context.

How and why do T cells and their derived cytokines affect the injured and healthy brain?

The evolution of adaptive immunity provides enhanced defence against specific pathogens, as well as homeostatic immune surveillance of all tissues. Despite being 'immune privileged', the CNS uses the assistance of the immune system in physiological and pathological states. In this Opinion article, we discuss the influence of adaptive immunity on recovery after CNS injury and on cognitive and social brain function. We further extend a hypothesis that the pro-social effects of interferon-regulated genes were initially exploited by pathogens to increase host-host transmission, and that these genes were later recycled by the host to form part of an immune defence programme. In this way, the evolution of adaptive immunity may reflect a host-pathogen 'arms race'.

Innate lymphoid cell-derived cytokines in autoimmune diseases

The most recently recognized types of immune cells, the innate lymphoid cells (ILCs), have been sub-divided according to respective distinct expression profiles of regulatory factors or/and cytokines. ILCs have also been shown to participate in a variety of beneficial immune responses, including participation in attack against pathogens and mediation of the pre-inflammatory and inflammatory responses through their production of pro-inflammatory cytokines. As such, while the ILCs exert protective effects they may also become detrimental upon dysregulation. Indeed, recent studies of the ILCs have revealed a strong association with the advent and pathogenesis of several common autoimmune diseases, including psoriasis, inflammatory bowel disease (IBD) and multiple sclerosis (MS). Though the ILCs belong to lineage negative cells that are distinctive from the Th cells, the profiles of secreted cytokines from the ILCs overlap with those of the corresponding Th subsets. Nevertheless, considering that the ILCs belong to the innate immune system and the Th cells belong to the adaptive immune system, it is expected that the ILCs should function at the early stage of diseases and the Th cells should exert predominant effects at the late stage of diseases. Therefore, it is intriguing to consider targeting of ILCs for therapy by targeting the corresponding cytokines at the early stage of diseases, with the late stage cytokine targeting mainly influencing the Th cells' function. Here, we review the knowledge to date on the roles of ILCs in various autoimmune diseases and discuss their potential as new therapeutic targets.

The single nucleotide variant rs12722489 determines differential estrogen receptor binding and enhancer properties of an IL2RA intronic region

We studied functional effect of rs12722489 single nucleotide polymorphism located in the first intron of human IL2RA gene on transcriptional regulation. This polymorphism is associated with multiple autoimmune conditions (rheumatoid arthritis, multiple sclerosis, Crohn's disease, and ulcerative colitis). Analysis in silico suggested significant difference in the affinity of estrogen receptor (ER) binding site between alternative allelic variants, with stronger predicted affinity for the risk (G) allele. Electrophoretic mobility shift assay showed that purified human ERα bound only G variant of a 32-bp genomic sequence containing rs12722489. Chromatin immunoprecipitation demonstrated that endogenous human ERα interacted with rs12722489 genomic region in vivo and DNA pull-down assay confirmed differential allelic binding of amplified 189-bp genomic fragments containing rs12722489 with endogenous human ERα. In a luciferase reporter assay, a kilobase-long genomic segment containing G but not A allele of rs12722489 demonstrated enhancer properties in MT-2 cell line, an HTLV-1 transformed human cell line with a regulatory T cell phenotype.

Environmental factors in autoimmune diseases and their role in multiple sclerosis

An increase in autoimmune diseases poses a socioeconomic challenge worldwide. Predisposing genetic risk has been identified, yet environmental factors make up a significant part of the risk in disease initiation and propagation. Next to improved hygiene and a gross reduction of infections, changes in dietary habits are one of the most evident Western lifestyle factors potentially associated with the increase in autoimmune diseases. Growing evidence suggests that particularly a typical 'Western diet', rich in saturated fat and salt and related pathologies can have a profound impact on local and systemic immune responses under physiologic and autoimmune conditions such as in multiple sclerosis (MS). In this review, we discuss recent findings on environmental factors influencing autoimmunity with an emphasis on the impact of 'Western diet' on immune homeostasis and gut microbiota in MS.

Tertiary Lymphoid Organs in Central Nervous System Autoimmunity

Multiple sclerosis (MS) is an autoimmune disease characterized by chronic inflammation in the central nervous system (CNS), which results in permanent neuronal damage and substantial disability in patients. Autoreactive T cells are important drivers of the disease; however, the efficacy of B cell depleting therapies uncovered an essential role for B cells in disease pathogenesis. They can contribute to inflammatory processes via presentation of autoantigen, secretion of pro-inflammatory cytokines, and production of pathogenic antibodies. Recently, B cell aggregates reminiscent of tertiary lymphoid organs (TLOs) were discovered in the meninges of MS patients, leading to the hypothesis that differentiation and maturation of autopathogenic B and T cells may partly occur inside the CNS. Since these structures were associated with a more severe disease course, it is extremely important to gain insight into the mechanism of induction, their precise function, and clinical significance. Mechanistic studies in patients are limited. However, a few studies in the MS animal model experimental autoimmune encephalomyelitis (EAE) recapitulate TLO formation in the CNS and provide new insight into CNS TLO features, formation, and function. This review summarizes what we know so far about CNS TLOs in MS and what we have learned about them from EAE models. It also highlights the areas that are in need of further experimental work, as we are just beginning to understand and evaluate the phenomenon of CNS TLOs.

RORγt Expression and Lymphoid Neogenesis in the Brain of Patients with Secondary Progressive Multiple Sclerosis

Ectopic B-cell follicle-like structures (ELS) are found in the meninges of patients with secondary progressive multiple sclerosis (SPMS). Because cells expressing the transcriptional regulator retinoic acid receptor-related orphan receptor-γt (RORγt) and producing interleukin 17 (IL17), e.g. T helper 17 cells and lymphoid tissue inducer (LTi) cells, have been implicated in the formation of ELS, we studied RORγt and IL17 expression in brain tissue from patients with SPMS an assessed their relationships to immune infiltrates and meningeal ELS. By immunohistochemistry, small numbers of RORγt-positive cells were detected in the meninges of 6 of 12 SPMS cases analyzed. RORγt-positive cells were localized in B-cell follicles or aggregates and nearby diffuse meningeal infiltrates, and predominantly co-expressed CD3. Only a few RORγt-positive, CD3-negative cells were observed, suggesting the presence of group 3 innate lymphoid cells, which comprise the LTi cell subset. Some IL17-positive cells, co-expressing in part RORγt and predominantly CD3, were found in meningeal B-cell follicles from 4 SPMS cases. Rare RORγt-positive and IL17-positive cells were detected in white matter. Gene expression analysis of laser dissected meningeal infiltrates and white matter lesions confirmed low frequencies and virtual absence of RORγt and IL17 signals, respectively. Thus, there is selective migration or survival of RORγt-positive cells in MS patient meninges and an association of these cells with ELS.