Immune-mediated genesis of multiple sclerosis

HLA Associations of Intrathecal IgG Production against Specific Viruses in Multiple Sclerosis

OBJECTIVE

Specific human leucocyte antigen (HLA) alleles are not only associated with higher risk to develop multiple sclerosis (MS) and other autoimmune diseases, but also with the severity of various viral and bacterial infections. Here, we analyzed the most specific biomarker for MS, that is, the polyspecific intrathecal IgG antibody production against measles, rubella, and varicella zoster virus (MRZ reaction), for possible HLA associations in MS.

METHODS

We assessed MRZ reaction from 184 Swiss patients with MS and clinically isolated syndrome (CIS) and 89 Swiss non-MS/non-CIS control patients, and performed HLA sequence-based typing, to check for associations of positive MRZ reaction with the most prevalent HLA alleles. We used a cohort of 176 Swedish MS/CIS patients to replicate significant findings.

RESULTS

Whereas positive MRZ reaction showed a prevalence of 38.0% in MS/CIS patients, it was highly specific (97.7%) for MS/CIS. We identified HLA-DRB1*15:01 and other tightly linked alleles of the HLA-DR15 haplotype as the strongest HLA-encoded risk factors for a positive MRZ reaction in Swiss MS/CIS (odds ratio [OR], 3.90, 95% confidence interval [CI] 2.05-7.46, padjusted = 0.0004) and replicated these findings in Swedish MS/CIS patients (OR 2.18, 95%-CI 1.16-4.02, padjusted = 0.028). In addition, female MS/CIS patients had a significantly higher probability for a positive MRZ reaction than male patients in both cohorts combined (padjusted <0.005).

INTERPRETATION

HLA-DRB1*15:01, the strongest genetic risk factor for MS, and female sex, 1 of the most prominent demographic risk factors for developing MS, predispose in MS/CIS patients for a positive MRZ reaction, the most specific CSF biomarker for MS. ANN NEUROL 2024;95:1112-1126.

Neuroprotective effect of curcumin against experimental autoimmune encephalomyelitis-induced cognitive and physical impairments in mice: an insight into the role of the AMPK/SIRT1 pathway

Multiple sclerosis (MS) is an incurable chronic neurodegenerative disease where autoimmunity, oxidative stress, and neuroinflammation collaboration predispose myelin sheath destruction. Interestingly, curcumin, a natural polyphenol, showed a neuroprotective effect in numerous neurodegenerative diseases, including MS. Nevertheless, the influence of curcumin against MS-induced cognitive impairment is still vague. Hence, we induced experimental autoimmune encephalomyelitis (EAE) in mice using spinal cord homogenate (SCH) and complete Freund's adjuvant, which eventually mimic MS. This study aimed not only to evaluate curcumin efficacy against EAE-induced cognitive and motor dysfunction, but also to explore a novel mechanism of action, by which curcumin exerts its beneficial effects in MS. Curcumin (200 mg/kg/day) efficacy was evaluated by behavioral tests, histopathological examination, and biochemical tests. Concisely, curcumin amended EAE-induced cognitive and motor impairments, as demonstrated by the behavioral tests and histopathological examination of the hippocampus. Interestingly, curcumin activated the adenosine monophosphate (AMP)-activated protein kinase/silent mating type information regulation 2 homolog 1 (AMPK/SIRT1) axis, which triggered cyclic AMP response element-binding protein/brain-derived neurotrophic factor/myelin basic protein (CREB/BDNF/MBP) pathway, hindering demyelination of the corpus callosum. Furthermore, AMPK/SIRT1 activation augmented nuclear factor erythroid 2-related factor 2 (Nrf2), a powerful antioxidant, amending EAE-induced oxidative stress. Additionally, curcumin abolished EAE-induced neuroinflammation by inhibiting Janus kinase 2 /signal transducers and activators of transcription 3 (JAK2/STAT3) axis, by various pathways, including AMPK/SIRT1 activation. JAK2/STAT3 inhibition halts inflammatory cytokines synthesis. In conclusion, curcumin's neuroprotective effect in EAE is controlled, at least in part, by AMPK/SIRT1 activation, which ultimately minimizes EAE-induced neuronal demyelination, oxidative stress, and neuroinflammation.

The Impact of Cytomegalovirus Infection on Natural Killer and CD8+ T Cell Phenotype in Multiple Sclerosis

Multiple sclerosis (MS) is a debilitating neurological disease that has been classified as an immune-mediated attack on myelin, the protective sheath of nerves. Some aspects of its pathogenesis are still unclear; nevertheless, it is generally established that viral infections influence the course of the disease. Cytomegalovirus (CMV) is a major pathogen involved in alterations of the immune system, including the expansion of highly differentiated cytotoxic CD8+ T cells and the accumulation of adaptive natural killer (NK) cells expressing high levels of the NKG2C receptor. In this study, we evaluated the impact of latent CMV infection on MS patients through the characterization of peripheral NK cells, CD8+ T cells, and NKT-like cells using flow cytometry. We evaluated the associations between immune cell profiles and clinical features such as MS duration and MS progression, evaluated using the Expanded Disability Status Scale (EDSS). We showed that NK cells, CD8+ T cells, and NKT-like cells had an altered phenotype in CMV-infected MS patients and displayed high levels of the NKG2C receptor. Moreover, in MS patients, increased NKG2C expression levels were found to be associated with higher EDSS scores. Overall, these results support the hypothesis that CMV infection imprints the immune system by modifying the phenotype and receptor repertoire of NK and CD8+ T cells, suggesting a detrimental role of CMV on MS progression.

Mitochondrial and metabolic dysfunction of peripheral immune cells in multiple sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disorder characterized by the infiltration of inflammatory cells and demyelination of nerves. Mitochondrial dysfunction has been implicated in the pathogenesis of MS, as studies have shown abnormalities in mitochondrial activities, metabolism, mitochondrial DNA (mtDNA) levels, and mitochondrial morphology in immune cells of individuals with MS. The presence of mitochondrial dysfunctions in immune cells contributes to immunological dysregulation and neurodegeneration in MS. This review provided a comprehensive overview of mitochondrial dysfunction in immune cells associated with MS, focusing on the potential consequences of mitochondrial metabolic reprogramming on immune function. Current challenges and future directions in the field of immune-metabolic MS and its potential as a therapeutic target were also discussed.

Curcumin's spice-infused therapeutic promise: disease severity alleviation in a mouse model of multiple sclerosis via modulation of immune responses

BACKGROUND

Multiple sclerosis (MS) is an autoimmune central nervous system (CNS) disorder indicated by demyelination, chronic inflammation, and neuronal destruction. Regional demyelination, inflammation responses, scar development, and various axonal damage are pathological characteristics of MS. Curcumin is a hydrophobic polyphenol extracted from the rhizome of the turmeric plant. In addition to anti-inflammatory effects, beneficial therapeutic effects such as antioxidant, anti-cancer and nerve protection have also been seen from this compound. The purpose of the current investigation was to provide light on the potential benefits of Curcumin in treating experimental autoimmune encephalomyelitis (EAE), the animal model of MS.

METHODS AND RESULTS

in Female C57BL/6 mice were used to induce EAE through myelin oligodendroglial glycoprotein (MOG). Curcumin doses of 100 and 200 mg/kg were administered orally in the treatment groups starting on the first day of EAE induction. Brains and splenocytes were extracted from euthanized animals on day 25 following EAE induction. Demyelination and leukocyte infiltration, proliferation, cytokine, and gene expression profiles were assessed. Our findings demonstrate that both low and high doses of Curcumin decreased the progression of EAE. Histological analyses revealed low infiltration of leukocytes into the CNS. Curcumin therapy enhanced Th2 and Treg cell secretion of IL-4, IL-10, and TGF-β although considerably decreasing IFN-γ and TNF-α. Curcumin-induced Th2 and Treg cell cytokine production and transcription factor gene expression (IL-13, GATA3, STAT6 and IL-35, CTLA4, Foxp3) and anti-inflammatory cytokines (IL-27, IL-33).

CONCLUSION

Overall, these findings provide additional evidence that Curcumin can slow disease development and alleviate symptoms in EAE through stimulating Treg and Th2 cell polarization. They support Curcumin's potential therapeutic role in MS.

Role of DAMPs and cell death in autoimmune diseases: the example of multiple sclerosis

Multiple sclerosis is a chronic neuroinflammatory demyelinating disease of the central nervous system (CNS) of unknown etiology and still incompletely clarified pathogenesis. The disease is generally considered a disorder resulting from a complex interplay between environmental risk factors and predisposing causal genetic variants. To examine the etiopathogenesis of the disease, two complementary pre-clinical models are currently discussed: the "outside-in" model proposing a peripherally elicited inflammatory/autoimmune attack against degraded myelin as the cause of the disease, and the "inside-out" paradigm implying a primary cytodegenerative process of cells in the CNS that triggers secondary reactive inflammatory/autoimmune responses against myelin debris. In this review, the integrating pathogenetic role of damage-associated molecular patterns (DAMPs) in these two scenario models is examined by focusing on the origin and sources of these molecules, which are known to promote neuroinflammation and, via activation of pattern recognition receptor-bearing antigen-presenting cells, drive and shape autoimmune responses. In particular, environmental factors are discussed that are conceptually defined as agents which produce endogenous DAMPs via induction of regulated cell death (RCD) or act themselves as exogenous DAMPs. Indeed, in the field of autoimmune diseases, including multiple sclerosis, recent research has focused on environmental triggers that cause secondary events in terms of subroutines of RCD, which have been identified as prolific sources of DAMPs. Finally, a model of a DAMP-driven positive feed-forward loop of chronic inflammatory demyelinating processes is proposed, aimed at reconciling the competing "inside-out" and "outside-in" paradigms.

Oral Pathobionts Promote MS-like Symptoms in Mice

Dysbiotic oral microbiota has been associated with multiple sclerosis. However, the role and mechanism of oral microbiota in the development of multiple sclerosis are still elusive. Here, we demonstrated that ligature-induced periodontitis (LIP) aggravated experimental autoimmune encephalomyelitis (EAE) in mice, and this was likely dependent on the expansion of T helper 17 (Th17) cells. LIP increased the splenic richness of Enterobacter sp., which was able to induce the expansion of splenic Th17 cells and aggravate EAE in mice. LIP also led to enrichment of Erysipelotrichaceae sp. in the gut and increased Th17 cells in the large intestinal lamina propria of EAE mice. Fecal microbiota transplantation from EAE mice with LIP also promoted EAE symptoms. In conclusion, periodontitis exacerbates EAE, likely through ectopic colonization of oral pathobionts and expansion of Th17 cells.

TLR9/FCRL3 regulates B cell viability, apoptosis, and antibody and IL-10 production through ERK1/2, p38, and STAT3 signaling pathways

B cells play a role in the progression of multiple sclerosis (MS) and are closely related to Fc-receptor like-3 (FCRL3), but little is known about FCRL3 in B cells and MS. Activation of TLR9 in B cells with CpG found that CpG promoted FCRL3 expression in a dose- and time-dependent manner. CpG significantly activated ERK1/2, p38, and STAT3 pathways, and FCRL3 overexpression further promoted the activation of these pathways, while FCRL3 siRNA significantly inhibited the activation of these pathways by CpG. CpG stimulation significantly promoted the viability of B cells, inhibited cell apoptosis, and enhanced the production of antibodies and secretion of IL-10 by B cells. FCRL3 siRNA blocked most of the above regulatory effects of CpG, but promoted the further production of antibodies by B cells. FCRL3 overexpression enhanced the pro-survival, anti-apoptotic, and IL-10-inducing effects of CpG, but inhibited the effect of CpG on promoting antibody production. After adding inhibitors of ERK1/2, p38, and STAT3 pathways, respectively, the effects of CpG on promoting cell viability, antibody production, and IL-10 secretion were significantly reduced, but the anti-apoptotic effect of CpG was only affected by the blockade of STAT3 pathway. In addition, FCRL3 regulated B cell antibody and IL-10 secretion mainly through its ITIMs. These results indicate that TLR9 activation affects B cell proliferation, apoptosis, antibody production, and IL-10 secretion by upregulating FCRL3 expression, and is associated with ERK1/2, p38, and STAT3 pathways. Therefore, FCRL3 may be an important target for the diagnosis and treatment of B cell-related diseases.

Ceramide kinase knockout ameliorates multiple sclerosis-like behaviors and demyelination in cuprizone-treated mice

Changes in sphingolipid metabolism regulate and/or alter many cellular functions in the brain. Ceramide, a central molecule of sphingolipid metabolism, is phosphorylated to ceramide-1-phosphate (C1P) by ceramide kinase (CerK). CerK and C1P were reported to regulate many cellular responses, but their roles in immune-related diseases in vivo have not been well elucidated. Thus, we investigated the effects of CerK knockout on the onset/progression of multiple sclerosis (MS), which is a chronic neurodegenerative disease accompanied by the loss of myelin sheaths in the brain. MS-model mice were prepared using a diet containing the copper chelator cuprizone (CPZ). Treatment of 8-week-old mice with 0.2% CPZ for 8 weeks resulted in motor dysfunction based on the Rota-rod test, and caused the loss of myelin-related proteins (MRPs) in the brain and demyelination in the corpus callosum without affecting synaptophysin levels. CerK knockout, which did not affect developmental changes in MRPs, ameliorated the motor dysfunction, loss of MRPs, and demyelination in the brain in CPZ-treated mice. Loss of tail tonus, another marker of motor dysfunction, was detected at 1 week without demyelination after CPZ treatment in a CerK knockout-independent manner. CPZ-induced loss of tail tonus progressed, specifically in female mice, to 6-8 weeks, and the loss was ameliorated by CerK knockout. Activities of ceramide metabolic enzymes including CerK in the lysates of the brain were not affected by CPZ treatment. Inhibition of CerK as a candidate for MS treatment was discussed.

The GPIb-IX complex on platelets: insight into its novel physiological functions affecting immune surveillance, hepatic thrombopoietin generation, platelet clearance and its relevance for cancer development and metastasis

The glycoprotein (GP) Ib-IX complex is a platelet receptor that mediates the initial interaction with subendothelial von Willebrand factor (VWF) causing platelet arrest at sites of vascular injury even under conditions of high shear. GPIb-IX dysfunction or deficiency is the reason for the rare but severe Bernard-Soulier syndrome (BSS), a congenital bleeding disorder. Although knowledge on GPIb-IX structure, its basic functions, ligands, and intracellular signaling cascades have been well established, several advances in GPIb-IX biology have been made in the recent years. Thus, two mechanosensitive domains and a trigger sequence in GPIb were characterized and its role as a thrombin receptor was deciphered. Furthermore, it became clear that GPIb-IX is involved in the regulation of platelet production, clearance and thrombopoietin secretion. GPIb is deemed to contribute to liver cancer development and metastasis. This review recapitulates these novel findings highlighting GPIb-IX in its multiple functions as a key for immune regulation, host defense, and liver cancer development.

Crosstalk of Microorganisms and Immune Responses in Autoimmune Neuroinflammation: A Focus on Regulatory T Cells

Regulatory T cells (Tregs) are the major determinant of peripheral immune tolerance. Many Treg subsets have been described, however thymus-derived and peripherally induced Tregs remain the most important subpopulations. In multiple sclerosis, a prototypical autoimmune disorder of the central nervous system, Treg dysfunction is a pathogenic hallmark. In contrast, induction of Treg proliferation and enhancement of their function are central immune evasion mechanisms of infectious pathogens. In accordance, Treg expansion is compartmentalized to tissues with high viral replication and prolonged in chronic infections. In friend retrovirus infection, Treg expansion is mainly based on excessive interleukin-2 production by infected effector T cells. Moreover, pathogens seem also to enhance Treg functions as shown in human immunodeficiency virus infection, where Tregs express higher levels of effector molecules such as cytotoxic T-lymphocyte-associated protein 4, CD39 and cAMP and show increased suppressive capacity. Thus, insights into the molecular mechanisms by which intracellular pathogens alter Treg functions might aid to find new therapeutic approaches to target central nervous system autoimmunity. In this review, we summarize the current knowledge of the role of pathogens for Treg function in the context of autoimmune neuroinflammation. We discuss the mechanistic implications for future therapies and provide an outlook for new research directions.

Retinal and Brain Microglia in Multiple Sclerosis and Neurodegeneration

Microglia are the resident immune cells of the central nervous system (CNS), including the retina. Similar to brain microglia, retinal microglia are responsible for retinal surveillance, rapidly responding to changes in the environment by altering morphotype and function. Microglia become activated in inflammatory responses in neurodegenerative diseases, including multiple sclerosis (MS). When activated by stress stimuli, retinal microglia change their morphology and activity, with either beneficial or harmful consequences. In this review, we describe characteristics of CNS microglia, including those in the retina, with a focus on their morphology, activation states and function in health, ageing, MS and other neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, glaucoma and retinitis pigmentosa, to highlight their activity in disease. We also discuss contradictory findings in the literature and the potential ways of reducing inconsistencies in future by using standardised methodology, e.g., automated algorithms, to enable a more comprehensive understanding of this exciting area of research.

NK Cells in Autoimmune Diseases: Protective or Pathogenic?

Autoimmune diseases generally result from the loss of self-tolerance (i.e., failure of the immune system to distinguish self from non-self), and are characterized by autoantibody production and hyperactivation of T cells, which leads to damage of specific or multiple organs. Thus, autoimmune diseases can be classified as organ-specific or systemic. Genetic and environmental factors contribute to the development of autoimmunity. Recent studies have demonstrated the contribution of innate immunity to the onset of autoimmune diseases. Natural killer (NK) cells, which are key components of the innate immune system, have been implicated in the development of multiple autoimmune diseases such as systemic lupus erythematosus, type I diabetes mellitus, and autoimmune liver disease. However, NK cells have both protective and pathogenic roles in autoimmunity depending on the NK cell subset, microenvironment, and disease type or stage. In this work, we review the current knowledge of the varied roles of NK cell subsets in systemic and organic-specific autoimmune diseases and their clinical potential as therapeutic targets.

Risk factors of multiple sclerosis in Aseer region, Kingdom of Saudi Arabia A case-control study

OBJECTIVES

To investigate socio-demographic and environmental risk factors of multiple sclerosis (MS) in Aseer region, Kingdom of Saudi Arabia (KSA).

METHODS

This was a retrospective, record, and interview based matched case control study completed in the neurology clinics at tertiary hospitals in Aseer, KSA. It included 82 MS cases and 82 controls. The study used a structured questionnaire to collect information on key socio-demographic and environmental exposures. The main outcome measure was a statistically significant relationship of key socio-demographic and environmental risk factors with MS.

RESULTS

A total of 82 registered patients, 50 were females, resulting in a female to male ratio of 1.56:1. Various risk factors were found to have a statistically significant association with MS which included female (OR=3.01, 95% CI [1.59:5.69]; p<0.001), family history of MS (OR=2.1, 95%CI [2.4:1.7] p=0.04), low exposure to sunlight (OR=2.02, 95%CI [2.53: 9.9] p<0.001), only fed breast milk in childhood (OR=0.46, 95%CI [0.55:0.39]; p<0.001), parental consanguinity (OR=2.17 95%CI [4.11:1.14] p=0.017), history of chickenpox (OR=15.59 95% CI [68.7:3.55]; p<0.01). On using multiple logistic regression, chicken pox infection (AOR=0.045, 95%CI [0.015-0.135]; p=0.001)and low sun-exposure (AOR=.271, 95%CI [.121-.609]; p<0.05) were deduced as the predictors of MS in this region.

CONCLUSION

This study offers unique insights into the risk factors of MS. Low sun exposure and childhood chickenpox are significantly related to the development of MS in the Aseer region.

Glycosylation in Autoimmune Diseases

Autoimmune diseases are accompanied by changes in protein glycosylation, in both the immune system and target tissues. The best-studied alteration in autoimmunity is agalactosylation of immunoglobulin G (IgG), characterized primarily in rheumatoid arthritis (RA), and then detected also in systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), and multiple sclerosis (MS). The rebuilding of IgG N-glycans in RA correlates with the relapses and remissions of the disease, is associated with physiological states such as pregnancy but also depends on applied anti-inflammatory therapy. In turn, a decreased core fucosylation of the whole pool of IgG N-glycans is a serum glycomarker in autoimmune thyroid diseases (AITD) encompassing Hashimoto's thyroiditis (HT) and Grave's disease (GD). However, fucosylation of anti-thyroglobulin IgG (an immunological marker of HT) was elevated in HT serum. Core fucosylation of IgG oligosaccharides was also lowered in MS and SLE. In AITD and IBD, chronic inflammation T lymphocytes showed the reduced expression of MGAT5 gene encoding β1,6-N-acetylglucosaminyltransferase V (GnT-V) responsible for β1,6-branching of N-glycans, which is important for T cell receptor activation. Structural changes of glycans have a profound effect on the pro-inflammatory activity of immune cells and serum immune proteins, including IgG in autoimmunity.

Inadequate Vaccine Responses in Children With Multiple Sclerosis

Objective: Immunizations against Hepatitis B virus (HBV) and Varicella Zoster virus (VZV), are recommended for patients with pediatric onset multiple sclerosis (POMS) and may be required prior to initiation of some disease modifying therapies. However, the efficacy of routine vaccine administration in POMS has never been studied. We sought to assess the humoral mediated vaccine response to HBV and VZV in children with POMS. Methods: A multi-center retrospective chart-based review of 62 patients with POMS was performed. Clinical data and antibody titers against HBV and VZV were collected prior to initiation of disease modifying therapy or steroids and compared to institutional control data, using t-test and chi squared analysis. Results: There were low rates of immunity against both HBV and VZV (33 and 25% respectively) among individuals with POMS. Fifteen individuals (24%) were non-immune to both. Compared to institutional control data, individuals with POMS were significantly less likely to be immune to and HBV (p = 0.003, 95% CI: 0.22-0.75) and VZV (p < 0.001, 95% CI: 0.09-0.39). Interpretation: Individuals with POMS have low rates of antibody-mediated immunity against HBV and VZV, despite receiving the appropriate vaccinations. This suggests an association between POMS and systemic immune dysregulation although further study is needed.

Gut eukaryotic virome in colorectal carcinogenesis: Is that a trigger?

The human gut microbiota is composed of bacteria and viruses that might be associated with colorectal cancer (CRC) onset and progression. Indeed, although viral infections have been reported to be the primary trigger in many diseases, the role of eukaryotic viruses populating the gut mucosa during early colorectal carcinogenesis is underinvestigated. Human eukaryotic viruses in the gut were found to induce alterations of the immune homeostasis so that some viral-dependent mechanisms likely able to induce DNA alterations in the bowel wall have been proposed, although no demonstration is available yet. However, thanks to the latest advancements in computational biology and the implementation of the bioinformatic pipelines, the option of establishing a direct causative link between intestinal virome and CRC will be possible soon, hopefully paving the way to innovative therapeutic strategies blocking or reverting the CRC pathogenesis.

The Role of Extracellular Vesicles in Demyelination of the Central Nervous System

It is being increasingly demonstrated that extracellular vesicles (EVs) are deeply involved in the physiology of the central nervous system (CNS). Processes such as synaptic activity, neuron-glia communication, myelination and immune response are modulated by EVs. Likewise, these vesicles may participate in many pathological processes, both as triggers of disease or, on the contrary, as mechanisms of repair. EVs play relevant roles in neurodegenerative disorders such as Alzheimer’s or Parkinson’s diseases, in viral infections of the CNS and in demyelinating pathologies such as multiple sclerosis (MS). This review describes the involvement of these membrane vesicles in major demyelinating diseases, including MS, neuromyelitis optica, progressive multifocal leukoencephalopathy and demyelination associated to herpesviruses.