Multiple sclerosis: immunopathogenesis and controversies in defining the cause

Discovery of Novel Azaindoles as Potent and Selective PI3Kδ Inhibitors for Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disorder of the central nervous system and the unmet need for MS treatment demands new therapeutic development. Particularly, PI3Kδ is a high-value target for autoimmune disease, while the investigation of PI3Kδ inhibitors for MS therapy is relatively scarce. Herein, we report a novel class of azaindoles as PI3Kδ inhibitors for MS treatment. Compound 31, designed via nitrogen bioisosterism, displayed excellent PI3Kδ inhibitory activity and selectivity. In vitro assay showed that 31 exhibited superior activity on T lymphocytes to inhibit the proliferation of CD4+, CD8+, and CD3+ T cells. In the experimental autoimmune encephalomyelitis (EAE) model, 31 showed a comparable therapeutical efficacy with Dexamethasone to significantly ameliorate EAE symptoms. Mechanistic studies showed that compound 31 could significantly inhibit the PI3K/AKT/mTOR signaling pathway and inhibited T-cell proliferation and differentiation. Overall, this work provides a new structural PI3Kδ inhibitor and a new vision for MS therapy.

Deciphering crucial genes in multiple sclerosis pathogenesis and drug repurposing: A systems biology approach

This study employed systems biology and high-throughput technologies to analyze complex molecular components of MS pathophysiology, combining data from multiple omics sources to identify potential biomarkers and propose therapeutic targets and repurposed drugs for MS treatment. This study analyzed GEO microarray datasets and MS proteomics data using geWorkbench, CTD, and COREMINE to identify differentially expressed genes associated with MS disease. Protein-protein interaction networks were constructed using Cytoscape and its plugins, and functional enrichment analysis was performed to identify crucial molecules. A drug-gene interaction network was also created using DGIdb to propose medications. This study identified 592 differentially expressed genes (DEGs) associated with MS disease using GEO, proteomics, and text-mining datasets. 37 DEGs were found to be important by topographical network studies, and 6 were identified as the most significant for MS pathophysiology. Additionally, we proposed six drugs that target these key genes. Crucial molecules identified in this study were dysregulated in MS and likely play a key role in the disease mechanism, warranting further research. Additionally, we proposed repurposing certain FDA-approved drugs for MS treatment. Our in silico results were supported by previous experimental research on some of the target genes and drugs. SIGNIFICANCE: As the long-lasting investigations continue to discover new pathological territories in neurodegeneration, here we apply a systems biology approach to determine multiple sclerosis's molecular and pathophysiological origin and identify multiple sclerosis crucial genes that contribute to candidating new biomarkers and proposing new medications.

Th17/IL-17 Axis in HTLV-1-Associated Myelopathy Tropical Spastic Paraparesis and Multiple Sclerosis: Novel Insights into the Immunity During HAMTSP

Human T lymphotropic virus-associated myelopathy/tropical spastic paraparesis (HTLV/TSP), also known as HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and multiple sclerosis (MS) are chronic debilitating diseases of the central nervous system; although the etiology of which is different, similarities have been observed between these two demyelinating diseases, especially in clinical manifestation and immunopathogenesis. Exorbitant response of the immune system to the virus and neurons in CNS is the causative agent of HAM/TSP and MS, respectively. Helper T lymphocyte-17 cells (Th17s), a component of the immune system, which have a proven role in immunity and autoimmunity, mediate protection against bacterial/fungal infections. The role of these cells has been reviewed in several CNS diseases. A pivotal role for Th17s is presented in demyelination, even more axial than Th1s, during MS. The effect of Th17s is not well determined in HTLV-1-associated infections; however, the evidence that we have supplied in this review illustrates the attendance, also the role of Th17 cells during HAM/TSP. Furthermore, for better conception concerning the trace of these cells in HAM/TSP, a comparative characterization with MS, the resembling disease, has been applied here.

Contribution of common risk variants to multiple sclerosis in Orkney and Shetland

Orkney and Shetland, the population isolates that make up the Northern Isles of Scotland, are of particular interest to multiple sclerosis (MS) research. While MS prevalence is high in Scotland, Orkney has the highest global prevalence, higher than more northerly Shetland. Many hypotheses for the excess of MS cases in Orkney have been investigated, including vitamin D deficiency and homozygosity: neither was found to cause the high prevalence of MS. It is possible that this excess prevalence may be explained through unique genetics. We used polygenic risk scores (PRS) to look at the contribution of common risk variants to MS. Analyses were conducted using ORCADES (97/2118 cases/controls), VIKING (15/2000 cases/controls) and Generation Scotland (30/8708 cases/controls) data sets. However, no evidence of a difference in MS-associated common variant frequencies was found between the three control populations, aside from HLA-DRB1*15:01 tag SNP rs9271069. This SNP had a significantly higher risk allele frequency in Orkney (0.23, p value = 8 × 10-13) and Shetland (0.21, p value = 2.3 × 10-6) than mainland Scotland (0.17). This difference in frequency is estimated to account for 6 (95% CI 3, 8) out of 150 observed excess cases per 100,000 individuals in Shetland and 9 (95% CI 8, 11) of the observed 257 excess cases per 100,000 individuals in Orkney, compared with mainland Scotland. Common variants therefore appear to account for little of the excess burden of MS in the Northern Isles of Scotland.

Role of Peripheral Immune Cells in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic autoimmune disease that affects the myelination of the neurons present in the central nervous system (CNS). The exact etiology of MS development is unclear, but various environmental and genetic factors might play a role in initiating the disease. Experimental autoimmune encephalomyelitis (EAE) is a mouse model that is used to study the pathophysiology of MS disease as well as the effects of possible therapeutic agents. In addition, autoreactive immune cells trigger an inflammatory process upon the recognition of CNS antigens, which leads to destruction of the neurons. These include innate immune cells such as macrophages, dendritic cells, and natural killer cells. Additionally, the activation and extravasation of adaptive immune cells such as CD4+ T cells into the CNS may lead to further exacerbation of the disease. However, many studies revealed that immune cells could have either a protective or pathological role in MS. In this review, we highlight the roles of innate and adaptive immune cellular and soluble players that contribute to the pathogenesis of MS and EAE, which may be used as potential targets for therapy.

CD36-mediated uptake of myelin debris by macrophages and microglia reduces neuroinflammation

Background

The presence of foamy macrophages and microglia containing intracellular myelin remnants is a pathological hallmark of neurodegenerative disorders such as multiple sclerosis (MS). Despite the importance of myelin internalization in affecting both central nervous system repair and neuroinflammation, the receptors involved in myelin clearance and their impact on the phagocyte phenotype and lesion progression remain to be clarified.

Methods

Flow cytometry, quantitative PCR, and immunohistochemistry were used to define the mRNA and protein abundance of CD36 in myelin-containing phagocytes. The impact of CD36 and nuclear factor erythroid 2–related factor 2 (NRF2) on the phagocytic and inflammatory features of macrophages and microglia was assessed using a pharmacological CD36 inhibitor (sulfo-N-succinimidyl oleate) and Nrf2^−/− bone marrow-derived macrophages. Finally, the experimental autoimmune encephalomyelitis (EAE) model was used to establish the impact of CD36 inhibition on neuroinflammation and myelin phagocytosis in vivo.

Results

Here, we show that the fatty acid translocase CD36 is required for the uptake of myelin debris by macrophages and microglia, and that myelin internalization increased CD36 expression through NRF2. Pharmacological inhibition of CD36 promoted the inflammatory properties of myelin-containing macrophages and microglia in vitro, which was paralleled by a reduced activity of the anti-inflammatory lipid-sensing liver X receptors and peroxisome proliferator-activated receptors. By using the EAE model, we provide evidence that CD36 is essential for myelin debris clearance in vivo. Importantly, CD36 inhibition markedly increased the neuroinflammatory burden and disease severity in the EAE model.

Conclusion

Altogether, we show for the first time that CD36 is crucial for clearing myelin debris and suppressing neuroinflammation in demyelinating disorders such as MS.

Comparison of Theiler's Murine Encephalomyelitis Virus Induced Spinal Cord and Peripheral Nerve Lesions Following Intracerebral and Intraspinal Infection

Hallmarks of Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease (TMEV-IDD) include spinal cord (SC) inflammation, demyelination and axonal damage occurring approximately 5-8 weeks after classical intracerebral (i.c.) infection. The aim of this study was to elucidate the consequences of intraspinal (i.s.) TMEV infection and a direct comparison of classical i.c. and intraspinal infection. Swiss Jim Lambert (SJL)-mice were i.s. infected with the BeAn strain of TMEV. Clinical investigations including a scoring system and rotarod analysis were performed on a regular basis. Necropsies were performed at 3, 7, 14, 28 and 63 days post infection (dpi) following i.s. and at 4, 7, 14, 28, 56, 98, 147 and 196 dpi following i.c. infection. Serial sections of formalin-fixed, paraffin-embedded SC and peripheral nerves (PN) were investigated using hematoxylin and eosin (HE) and immunohistochemistry. I.s. infected mice developed clinical signs and a deterioration of motor coordination approximately 12 weeks earlier than i.c. infected animals. SC inflammation, demyelination and axonal damage occurred approximately 6 weeks earlier in i.s. infected animals. Interestingly, i.s. infected mice developed PN lesions, characterized by vacuolation, inflammation, demyelination and axonal damage, which was not seen following i.c. infection. The i.s. infection model offers the advantage of a significantly earlier onset of clinical signs, inflammatory and demyelinating SC lesions and additionally enables the investigation of virus-mediated PN lesions.

TRPV4 Inhibition Improved Myelination and Reduced Glia Reactivity and Inflammation in a Cuprizone-Induced Mouse Model of Demyelination

The inhibition of demyelination and the promotion of remyelination are both considerable challenges in the therapeutic process for many central nervous system (CNS) diseases. Increasing evidence has demonstrated that neuroglial activation and neuroinflammation are responsible for myelin sheath damage during demyelinating disorders. It has been revealed that the nonselective cation channel transient receptor potential vanilloid 4 (TRPV4) profoundly affects a variety of physiological processes, including inflammation. However, its roles and mechanisms in demyelination have remained unclear. Here, for the first time, we found that there was a significant increase in TRPV4 in the corpus callosum in a demyelinated mouse model induced by cuprizone (CPZ). RN-1734, a TRPV4-antagonist, clearly alleviated demyelination and inhibited glial activation and the production of tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) without altering the number of olig2-positive cells. In vitro, RN-1734 treatment clearly inhibited the influx of calcium and decreased the levels of IL-1β and TNF-α in lipopolysaccharide (LPS)-activated microglial cells by suppressing NF-κB P65 phosphorylation. Apoptosis of oligodendrocyte induced by LPS-activated microglia was also alleviated by RN-1734. The results suggest that activation of TRPV4 in microglia is involved in oligodendrocyte apoptosis through the activation of the NF-κB signaling pathway, thus revealing a new mechanism of CNS demyelination.

Microglial MHC class II is dispensable for experimental autoimmune encephalomyelitis and cuprizone-induced demyelination

Microglia are resident immune cells in the CNS, strategically positioned to clear dead cells and debris, and orchestrate CNS inflammation and immune defense. In steady state, these macrophages lack MHC class II (MHCII) expression, but microglia activation can be associated with MHCII induction. Whether microglial MHCII serves antigen presentation for critical local T-cell restimulation in CNS auto-immune disorders or modulates microglial signaling output remains under debate. To probe for such scenarios, we generated mice harboring an MHCII deficiency in microglia, but not peripheral myeloid cells. Using the CX₃ CR1^CreER -based approach we report that microglial antigen presentation is obsolete for the establishment of EAE, with disease onset, progression, and severity unaltered in mutant mice. Antigen presentation-independent roles of microglial MHCII were explored using a demyelination model induced by the copper chelator cuprizone. Absence of microglial I-A^b did not affect the extent of these chemically induced white matter alterations, nor did it affect microglial proliferation or gene expression associated with locally restricted de- and remyelination.

Impacts of microbiome metabolites on immune regulation and autoimmunity

A vast number of studies have demonstrated a remarkable role for the gut microbiota and their metabolites in the pathogenesis of inflammatory diseases, including multiple sclerosis (MS). Recent studies in experimental autoimmune encephalomyelitis, an animal model of MS, have revealed that modifying certain intestinal bacterial populations may influence immune cell priming in the periphery, resulting in dysregulation of immune responses and neuroinflammatory processes in the central nervous system (CNS). Conversely, some commensal bacteria and their antigenic products can protect against inflammation within the CNS. Specific components of the gut microbiome have been implicated in the production of pro-inflammatory cytokines and subsequent generation of Th17 cells. Similarly, commensal bacteria and their metabolites can also promote the generation of regulatory T-cells (Treg), contributing to immune suppression. Short-chain fatty acids may induce Treg either by G-protein-coupled receptors or inhibition of histone deacetylases. Tryptophan metabolites may suppress inflammatory responses by acting on the aryl hydrocarbon receptor in T-cells or astrocytes. Interestingly, secretion of these metabolites can be impaired by excess consumption of dietary components, such as long-chain fatty acids or salt, indicating that the diet represents an environmental factor affecting the complex crosstalk between the gut microbiota and the immune system. This review discusses new aspects of host-microbiota interaction and the immune system with a special focus on MS as a prototype T-cell-mediated autoimmune disease of the CNS.

Hepcidin and metallothioneins as molecular base for sex-dependent differences in clinical course of experimental autoimmune encephalomyelitis in chronic iron overload

Multiple sclerosis is a chronic demyelinating disease of the central nervous system characterised by inflammatory and degenerative changes. It is considered that disease arises from the influence of environmental factors on genetically susceptible individuals. Recent researches, using magnetic resonance imaging, connected iron deposits in different brain regions with demyelinating process in multiple sclerosis patients. Although iron is an essential trace element important for many biological functions it could be harmful because iron excess can induce the production of reactive oxygen species, development of oxidative stress and lipid peroxidation which leads to demyelination. In experimental autoimmune encephalomyelitis model, the most common experimental animal model for multiple sclerosis, we recently found that chronic iron overload influences the clinical course of disease in Dark Agouti rats. In female rats iron overload accelerated the onset of disease, while in male rats it accelerated the progression of disease and increased mortality rate. We hypothesize that those differences arise on molecular level in different expression of stress response proteins hepcidin and metallothioneins in male and female iron overloaded rats. They are both upregulated by metal ions in both sexes. Hepcidin is additionally upregulated by estrogen in female rats and therefore causes higher degradation of iron exporter ferroportin and sequestration of iron in the cells, lowering the possibility for the development of oxidative stress. Antioxidative effect of metallothioneins could be increased in female rats because of their ability to reversibly exchange metal ions with the estrogen receptor. In case of iron excess metallothioneins release zinc, which is normally bound to them. Zinc binds to estrogen receptor and leaves metallothioneins binding domains free for iron, causing at least provisional cytoprotective effect. To test this hypothesis, we propose to determine and compare serum levels of hepcidin and estrogen using ELISA essay as well as expression and distribution of acute stress response proteins hepcidin and metallothioneins, iron and estrogen receptor in the brain and spinal cord tissue using immunohistochemistry in control and chronic iron overloaded male and female rats in experimental autoimmune encephalomyelitis model. It would be also possible to perform the same immunohistochemistry in the brain tissue of multiple sclerosis patients post mortem. The results of experiments could contribute to better understanding of cytoprotective mechanisms in chronic iron overload that could have possible therapeutic applications in iron disturbances. In order to elucidate whether common measure of systemic iron status, like ferritin, haemoglobin concentration and transferrin saturation levels, may be used to distinguish physiologic from potentially harmful iron levels in local disease, for example multiple sclerosis and Still's disease, well-designed clinical trials would be of great interest.

Experimental Models of Autoimmune Demyelinating Diseases in Nonhuman Primates

Human idiopathic inflammatory demyelinating diseases (IIDD) are a heterogeneous group of autoimmune inflammatory and demyelinating disorders of the central nervous system (CNS). These include multiple sclerosis (MS), the most common chronic IIDD, but also rarer disorders such as acute disseminated encephalomyelitis (ADEM) and neuromyelitis optica (NMO). Great efforts have been made to understand the pathophysiology of MS, leading to the development of a few effective treatments. Nonetheless, IIDD still require a better understanding of the causes and underlying mechanisms to implement more effective therapies and diagnostic methods. Experimental autoimmune encephalomyelitis (EAE) is a commonly used animal model to study the pathophysiology of IIDD. EAE is principally induced through immunization with myelin antigens combined with immune-activating adjuvants. Nonhuman primates (NHP), the phylogenetically closest relatives of humans, challenged by similar microorganisms as other primates may recapitulate comparable immune responses to that of humans. In this review, the authors describe EAE models in 3 NHP species: rhesus macaques ( Macaca mulatta), cynomolgus macaques ( Macaca fascicularis), and common marmosets ( Callithrix jacchus), evaluating their respective contribution to the understanding of human IIDD. EAE in NHP is a heterogeneous disease, including acute monophasic and chronic polyphasic forms. This diversity makes it a versatile model to use in translational research. This clinical variability also creates an opportunity to explore multiple facets of immune-mediated mechanisms of neuro-inflammation and demyelination as well as intrinsic protective mechanisms. Here, the authors review current insights into the pathogenesis and immunopathological mechanisms implicated in the development of EAE in NHP.

Macrophages in neuroinflammation: role of the renin-angiotensin-system

Macrophages are essential players of the innate immune system which are involved in the initiation and progression of various inflammatory and autoimmune diseases including neuroinflammation. In the past few years, it has become increasingly clear that the regulation of macrophage responses by the local tissue milieu is also influenced by mediators which were first discovered as regulators in the nervous or also cardiovascular system. Here, the renin-angiotensin system (RAS) is a major focus of current research. Besides its classical role in blood pressure control, body fluid, and electrolyte homeostasis, the RAS may influence (auto)immune responses, modulate T cells, and particularly act on macrophages via different signaling pathways. Activation of classical RAS pathways including angiotensin (Ang) II and AngII type 1 (AT₁R) receptors may drive pro-inflammatory macrophage responses in neuroinflammation via regulation of chemokines. More recently, alternative RAS pathways were described, such as binding of Ang-(1-7) to its receptor Mas. Signaling via Mas pathways may counteract some of the AngII/AT₁R-mediated effects. In macrophages, the Ang-(1-7)/Mas exerts beneficial effects on neuroinflammation via modulating macrophage polarization, migration, and T cell activation in vitro and in vivo. These data delineate a pivotal role of the RAS in inflammation of the nervous system and identify RAS modulation as a potential new target for immunotherapy with a special focus on macrophages.

Pathobiology of tobacco smoking and neurovascular disorders: untied strings and alternative products

Tobacco smoke (TS) is the leading cause of preventable deaths worldwide. In addition to a host of well characterized diseases including chronic obstructive pulmonary disease, oral and peripheral cancers and cardiovascular complications, epidemiological evidence suggests that chronic smokers are at equal risk to develop neurological and neurovascular complications such as multiple sclerosis, Alzheimer's disease, stroke, vascular dementia and small vessel ischemic disease (SVID). Unfortunately, few direct neurotoxicology studies of tobacco smoking and its pathogenic pathways have been produced so far. A major link between TS and CNS disorders is the blood-brain barrier (BBB). In this review article, we summarize the current understanding of the toxicological impact of TS on BBB physiology and function and major compensatory mechanisms such as nrf2- ARE signaling and anti-inflammatory pathways activated by TS. In the same context, we discuss the controversial role of antioxidant supplementation as a prophylactic and/or therapeutic approach in delaying or decreasing the disease complications in smokers. Further, we cover a number of toxicological studies associated with "reduced exposure" cigarette products including electronic cigarettes. Finally, we provide insights on possible avenues for future research including mechanistic studies using direct inhalation rodent models.

Differential roles of resident microglia and infiltrating monocytes in murine CNS autoimmunity

Macrophages can be of dual origin. Most tissue-resident macrophage compartments are generated before birth and subsequently maintain themselves independently from each other locally in healthy tissue. Under inflammatory conditions, these cells can however be complemented by macrophages derived from acute monocyte infiltrates. Due to the lack of suitable experimental systems, differential functional contributions of central nervous system (CNS)-resident microglia and monocyte-derived macrophages (MoMF) to CNS inflammation, such as experimental autoimmune encephalomyelitis (EAE), the mouse model of multiple sclerosis (MS), remain poorly understood. Here, we will review recent progress in this field that suggest distinct roles of microglia and MoMF in disease induction and progression, capitalizing on novel transgenic mouse models. The latter finding could have major implications for the rationale development of therapeutic approaches to the management of brain inflammation and MS therapy.

Multiple sclerosis and the role of immune cells

Multiple sclerosis (MS) is a complex disease with many different immune cells involved in its pathogenesis, and in particular T cells as the most recognized cell type. Recently, the innate immune system has also been researched for its effect on the disease. Hence, cells of the immune system play vital roles in either ameliorating or exacerbating the disease. The genetic and environmental factors, as well as the etiology and pathogenesis are of utmost importance for the development of MS. An insight into the roles play by T cells, B cells, natural killer cells, and dendritic cells in MS and the animal model experimental autoimmune encephalomyelitis, will be presented. Understanding the mechanisms of action for current therapeutic modalities should help developing new therapeutic tools to treat this disease and other autoimmune diseases.

Autoimmune disease triggered by infection with alphaproteobacteria

Despite having long been postulated, compelling evidence for the theory that microbial triggers drive autoimmunity has only recently been reported. A specific association between Novosphingobium aromaticivorans, an ubiquitous alphaproteobacterium, and primary biliary cirrhosis (PBC) has been uncovered in patients with PBC. Notably, the association between Novosphingobium infection and PBC has been confirmed in a mouse model in which infection leads to the development of liver lesions resembling PBC concomitant with the production of anti-PDC-E2 antibodies that cross-react with conserved PDC-E2 epitopes shared by Novosphingobium. The discovery of infectious triggers of autoimmunity is likely to change our current concepts about the etiology of various autoimmune syndromes and may suggest new and simpler ways to diagnose and treat these debilitating diseases.

Impact of vitamin A supplementation on RAR gene expression in multiple sclerosis patients

Vitamin A and its derivatives have been shown to modulate the immune system via retinoic acid receptor (RAR). This study explored the impact of retinyl palmitate supplementation on RAR subtype gene expression in peripheral blood mononuclear cells (PBMCs) in multiple sclerosis (MS) patients. The study designed as a double-blind randomized clinical trial in which relapsing remitting multiple sclerosis patients were evaluated. Both groups received one capsule 50,000 IU vitamin D3 per 2 weeks and one intramuscular injection interferon beta-1a per week. The intervention group received one 25,000 IU retinyl palmitate capsule daily for 6 months and the placebo group received one placebo capsule daily. The PBMCs were isolated from participants and the expression level changes of RAR-α and RAR-γ genes were determined by real-time PCR. After supplementation, in the intervention group, the RAR-α gene expression level was significantly decreased compared to the placebo group (p = 0.03); however, the expression of RAR-γ gene did not significantly change (p = 0.10). These results show that vitamin A supplementation can significantly downregulate the expression of RAR-α gene in PBMCs of MS patients that suggest the presence of in vivo regulatory mechanisms for the action of vitamin A on the immune system.

Association between multiple sclerosis and chronic periodontitis: a population-based pilot study

BACKGROUND AND PURPOSE

The pathogenesis of multiple sclerosis (MS) is still not fully understood, but multiple infections are known to be crucial in the development of the disease. Periodontitis caused by periodontopathic polymicrobial infections is among the most common chronic infectious disorders. This case-control study aimed to investigate the association between chronic periodontitis (CP) and MS using a population-based dataset in Taiwan.

METHODS

This study included 316 cases who had a diagnosis of MS and 1580 randomly selected controls. We performed conditional logistic regressions to investigate the association between MS and having been previously diagnosed with CP.

RESULTS

The results reveal that the prevalence of earlier CP was 25.6% and 15.4% for cases and controls, respectively (P < 0.001). Conditional logistic regression analysis revealed that cases were 1.86 [95% confidence interval (CI) = 1.39-2.48] times as likely as controls to have been previously diagnosed with CP, after adjusting for sociodemographic characteristics as well as hyperlipidemia, hypertension, coronary heart disease, alcohol abuse/alcohol-dependence syndrome, tobacco use disorder and chronic obstructive pulmonary disease. After analyzing by gender, it was realized that while female cases had a higher chance than female controls of having earlier CP (adjusted odds ratio = 2.08; 95% CI = 1.49-2.95), there was no statistical association detected between these two conditions in men.

CONCLUSIONS

This study provides evidence for an association between CP and MS in female, but not male, subjects. Further epidemiological studies are needed to confirm the association and gender-specific differences found in the present study.

Animal Models of MS Reveal Multiple Roles of Microglia in Disease Pathogenesis

Multiple sclerosis (MS) is a progressive inflammatory and demyelinating disease that affects more than 2.5 million people worldwide every year. Current therapies use mostly disease-modifying drugs, focusing on blocking and regulating systemic functions and the central nervous system (CNS) infiltration of immune cells; however, these therapies only attenuate or delay MS symptoms, but are not effective in halting the disease progression. More recent evidence indicated that regulation of inflammation within the CNS might be a better way to approach the treatment of the disease and microglia, the resident immune cells, may be a promising target of therapeutic studies. Microglia activation classically accompanies MS development, and regulation of microglia function changes the outcome of the disease. In this paper, we review the contributions of microglia to MS pathogenesis and discuss microglial functions in antigen presentation, cytokine release, and phagocytosis. We describe data both from animal and human studies. The significant impact of the timing, intensity, and differentiation fate of activated microglia is discussed, as they can modulate MS outcomes and potentially be critically modified for future therapeutic studies.

Experimental autoimmune encephalomyelitis evolution was not modified by multiple infections with Strongyloides venezuelensis

According to the hygiene hypothesis, the increased incidence of allergic and autoimmune diseases in developed countries is mainly explained by the decreased contact between the human population and certain environmental agents as lactobacillus, mycobacteria and helminths. In this study, we evaluated the effect of multiple infections with Strongyloides venezuelensis on the development of experimental autoimmune encephalomyelitis (EAE) in Lewis rats. Multiple infections before EAE induction were not able to change the evolution of the disease. No alterations were observed in weight loss, clinical score and inflammation intensity at the central nervous system. The presence of significant levels of parasite-specific IgG1 but not IgG2b suggested a Th2 polarization. However, the percentage and absolute number of CD4+CD25+Foxp3+ T cells were not changed, being their levels in the spleen and lymph nodes of infected rats comparable to the ones found in normal animals. These results suggest that a Th2-polarized response without concomitant expansion of Foxp3+ regulatory T cells was not able to modify EAE progression. Even though these results do not threaten the hygiene hypothesis, they suggest that this paradigm might be an oversimplification. They also emphasize the need of a study to compare the immunoregulatory ability associated with different helminth spp.

Identification of Cd101 as a susceptibility gene for Novosphingobium aromaticivorans-induced liver autoimmunity

Environmental and genetic factors define the susceptibility of an individual to autoimmune disease. Although common genetic pathways affect general immunological tolerance mechanisms in autoimmunity, the effects of such genes could vary under distinct immune challenges within different tissues. In this study, we demonstrate this by observing that autoimmune type 1 diabetes-protective haplotypes at the insulin-dependent diabetes susceptibility region 10 (Idd10) introgressed from chromosome 3 of C57BL/6 (B6) and A/J mice onto the NOD background increase the severity of autoimmune primary biliary cirrhosis induced by infection with Novosphingobium aromaticivorans, a ubiquitous alphaproteobacterium, when compared with mice having the NOD and NOD.CAST Idd10 type 1 diabetes-susceptible haplotypes. Substantially increased liver pathology in mice having the B6 and A/J Idd10 haplotypes correlates with reduced expression of CD101 on dendritic cells, macrophages, and granulocytes following infection, delayed clearance of N. aromaticivorans, and the promotion of overzealous IFN-γ- and IL-17-dominated T cell responses essential for the adoptive transfer of liver lesions. CD101-knockout mice generated on the B6 background also exhibit substantially more severe N. aromaticivorans-induced liver disease correlating with increased IFN-γ and IL-17 responses compared with wild-type mice. These data strongly support the hypothesis that allelic variation of the Cd101 gene, located in the Idd10 region, alters the severity of liver autoimmunity induced by N. aromaticivorans.

The human microbiome in multiple sclerosis: pathogenic or protective constituents?

The human microbiome is comprised of commensal and pathogenic microorganisms, which exert diverse effects in close proximity to the site of intection as well as in remote tissues through immune-mediated mechanisms. Multiple infectious agents have been implicated in the pathogenesis of multiple sclerosis (MS) with variable findings depending on the agent, techniques, and disease phenotype. Herein, the contributions of individual infectious agents to MS and their effects on the immune and nervous systems are reviewed, focusing on herpes viruses, coronaviruses, retroviruses, and synchronic infections. While infectious agents are often assumed to be pathogenic, their effects might also be beneficial to the host in the long-term, depending on age and the type of immunogen/pathogen exposure, as proposed by the hygiene hypothesis. The human microbiome has potential impact on future diagnostic and therapeutic issues in MS.

Osteopontin concentrations are increased in cerebrospinal fluid during attacks of multiple sclerosis

BACKGROUND

The cytokine osteopontin (OPN) is a potential key player in the immunopathogenesis of multiple sclerosis (MS) and a candidate biomarker for disease activity.

OBJECTIVE

The objective of this study was to examine concentrations of OPN in the cerebrospinal fluid (CSF) across the clinical spectrum of MS.

METHODS

Our research consisted of a cross-sectional study of patients from two randomized, placebo-controlled trials. Concentrations of OPN and other blood and CSF markers were determined using an enzyme-linked immunosorbent assay (ELISA). Samples were obtained from untreated patients with exacerbation of clinically isolated syndrome (CIS) (n = 25) and relapsing-remitting MS (RRMS) (n = 41) of whom 48 participated in clinical trials, randomly allocated to treatment with placebo or methylprednisolone (MP) and undergoing repeated sampling after 3 weeks. Furthermore, we obtained CSF and blood samples from patients with primary progressive MS (PPMS, n = 9), secondary progressive MS (SPMS, n = 28) and other neurological disorders (OND, n = 44), and blood samples from 24 healthy subjects.

RESULTS

OPN concentrations were significantly increased in the CSF of patients with CIS (p = 0.02) and RRMS (p < 0.001) in exacerbation compared to patients with OND, and increased levels of OPN were associated with high values of other biomarkers of inflammation. At 3-week follow-up CSF OPN concentrations had decreased significantly from baseline regardless treatment with placebo or MP. Patients with PPMS had increased OPN levels in the CSF (p = 0.004) and high CSF levels of OPN were associated with high degrees of disability.

CONCLUSIONS

OPN concentration in the CSF is a dynamic indicator of disease activity in RRMS, presumably reflecting ongoing inflammation. Increased CSF OPN concentrations in PPMS may indicate ongoing inflammation even in these patients.

Decreased production of TNF-alpha by lymph node cells indicates experimental autoimmune encephalomyelitis remission in Lewis rats

Experimental autoimmune encephalomyelitis (EAE) is mediated by CD4+ Th1 cells that mainly secrete IFN-gamma and TNF-alpha, important cytokines in the pathophysiology of the disease. Spontaneous remission is, in part, attributed to the down regulation of IFN-gamma and TNF-alpha by TGF-beta. In the current paper, we compared weight, histopathology and immunological parameters during the acute and recovery phases of EAE to establish the best biomarker for clinical remission. Female Lewis rats were immunised with myelin basic protein (MBP) emulsified with complete Freund's adjuvant. Animals were evaluated daily for clinical score and weight prior to euthanisation. All immunised animals developed the expected characteristics of EAE during the acute phase, including significant weight loss and high clinical scores. Disease remission was associated with a significant reduction in clinical scores, although immunised rats did not regain their initial weight values. Brain inflammatory infiltrates were higher during the acute phase. During the remission phase, anti-myelin antibody levels increased, whereas TNF-alpha and IFN-gamma production by lymph node cells cultured with MBP or concanavalin A, respectively, decreased. The most significant difference observed between the acute and recovery phases was in the induction of TNF-alpha levels in MBP-stimulated cultures. Therefore, the in vitro production of this cytokine could be used as a biomarker for EAE remission.

Human endogenous retroviruses and multiple sclerosis: innocent bystanders or disease determinants?

Human endogenous retroviruses (HERVs) constitute 5–8% of human genomic DNA and are replication incompetent despite expression of individual HERV genes from different chromosomal loci depending on the specific tissue. Several HERV genes have been detected as transcripts and proteins in the central nervous system, frequently in the context of neuroinflammation. The HERV-W family has received substantial attention in large part because of associations with diverse syndromes including multiple sclerosis (MS) and several psychiatric disorders. A HERV-W-related retroelement, multiple sclerosis retrovirus (MSRV), has been reported in MS patients to be both a biomarker as well as an effector of aberrant immune responses. HERV-H and HERV-K have also been implicated in MS and other neurological diseases but await delineation of their contributions to disease. The HERV-W envelope-encoded glycosylated protein, syncytin-1, is encoded by chromosome 7q21 and exhibits increased glial expression within MS lesions. Overexpression of syncytin-1 in glia induces endoplasmic reticulum stress leading to neuroinflammation and the induction of free radicals, which damage proximate cells. Syncytin-1's receptor, ASCT1 is a neutral amino acid transporter expressed on glia and is suppressed in white matter of MS patients. Of interest, antioxidants ameliorate syncytin-1's neuropathogenic effects raising the possibility of using these agents as therapeutics for neuroinflammatory diseases. Given the multiple insertion sites of HERV genes as complete and incomplete open reading frames, together with their differing capacity to be expressed and the complexities of individual HERVs as both disease markers and bioactive effectors, HERV biology is a compelling area for understanding neuropathogenic mechanisms and developing new therapeutic strategies.

Multiple sclerosis: an update for oral health care providers

Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating disease of the central nervous system. The disease mostly affects young adults and is increasing in prevalence and incidence. Multiple sclerosis is characterized by periods of activity and remission which, after numerous relapses, cause permanent neurologic deficits. Diagnosis of MS is based on patient history and clinical examination supplemented by the findings of radiologic and laboratory tests. Numerous motor and sensory disturbances occur in MS and may present in the orofacial region. This medical management update highlights issues that are important to the oral health care provider, including orofacial manifestations of MS and dental considerations for patients with MS.

Multiple sclerosis, osteoporosis, and vitamin D

Multiple sclerosis (MS) is associated with reduced bone mass and higher frequency of osteoporosis. Although high-dose short-term intravenous glucocorticoid regimens cause a decrease in bone formation, this effect is usually reversible and osteoporosis in MS patients may be independent of the short-term corticosteroid treatment. Clinical evidence suggests an important role of vitamin D as a modifiable risk factor in MS. Low circulating levels of vitamin D have been found in MS patients, especially during relapses, suggesting that vitamin D could be involved in the regulation of the clinical disease activity. Vitamin D mediates its function through a single vitamin D receptor (VDR). Polymorphisms of the VDR have major effects on vitamin D function and metabolism, and some VDR genotypes have been linked to osteoporosis and MS. Because the safety of high doses of vitamin D has not been established yet, vitamin D hasn't been used in enough doses to increase the serum level to a desired therapeutic target. Future clinical trials should determine the upper limit of vitamin D intake in order to achieve therapeutic benefit in MS patients.

Clinical implications of a possible role of vitamin D in multiple sclerosis

Hypovitaminosis D is currently one of the most studied environmental risk factors for multiple sclerosis (MS) and is potentially the most promising in terms of new clinical implications. These practical consequences, which could be applied to MS patients without further delay, constitute the main purpose of this review. Vitamin D is involved in a number of important general actions, which were not even suspected until quite recently. In particular, this vitamin could play an immunomodulatory role in the central nervous system. Many and varied arguments support a significant role for vitamin D in MS. In animal studies, vitamin D prevents and improves experimental autoimmune encephalomyelitis. Epidemiologically, latitude, past exposure to sun and the serum level of vitamin D influence the risk of MS, with, furthermore, significant links existing between these different factors. Clinically, most MS patients have low serum levels of vitamin D and are in a state of insufficiency or even deficiency compared to the international norm, which has been established on a metabolic basis. Large therapeutic trials using vitamin D are still lacking but the first results of phase I/II studies are promising. In the meantime, while awaiting the results of future therapeutic trials, it can no longer be ignored that many MS patients have a lack of vitamin D, which could be detected by a serum titration and corrected using an appropriate vitamin D supplementation in order to restore their serum level to within the normal range. From a purely medical point of view, vitamin D supplementation appears in this light to be unavoidable in order to improve the general state of these patients. Furthermore, it cannot currently be ruled out that this supplementation could also be neurologically beneficial.