Sex hormones in experimental autoimmune encephalomyelitis: implications for multiple sclerosis

Asymptomatic herpes simplex virus brain infection elicits cellular senescence phenotypes in the central nervous system of mice suffering multiple sclerosis-like disease

Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease affecting the central nervous system (CNS) in animals that parallels several clinical and molecular traits of multiple sclerosis in humans. Herpes simplex virus type 1 (HSV-1) infection mainly causes cold sores and eye diseases, yet eventually, it can also reach the CNS, leading to acute encephalitis. Notably, a significant proportion of healthy individuals are likely to have asymptomatic HSV-1 brain infection with chronic brain inflammation due to persistent latent infection in neurons. Because cellular senescence is suggested as a potential factor contributing to the development of various neurodegenerative disorders, including multiple sclerosis, and viral infections may induce a premature senescence state in the CNS, potentially increasing susceptibility to such disorders, here we examine the presence of senescence-related markers in the brains and spinal cords of mice with asymptomatic HSV-1 brain infection, EAE, and both conditions. Across all scenarios, we find a significant increases of senescence biomarkers in the CNS with some differences depending on the analyzed group. Notably, some senescence biomarkers are exclusively observed in mice with the combined conditions. These results indicate that asymptomatic HSV-1 brain infection and EAE associate with a significant expression of senescence biomarkers in the CNS.

The protective role of interaction between vitamin D, sex hormones and calcium in multiple sclerosis

Multiple sclerosis (MS) is a neurological disorder that causes disability and paralysis, especially among young adults. Although interactions of several factors, such as viral infections, autoimmunity, genetic and environmental factors, performance a role in the beginning and progression of the disease, the exact cause of MS is unknown to date. Different immune cells such as Th1 and Th17 play an impressive role in the immunopathogenesis of MS, while, regulatory cells such as Th2 and Treg diminish the severity of the illness. Sex hormones have a vital role in many autoimmune disorders, including multiple sclerosis. Testosterone, estrogen and progesterone have various roles in the progress of MS, which higher prevalence of disease in women and more severe in men reveals the importance of sex hormones' role in this disease. Vitamin D after chemical changes in the body, as an active hormone called calcitriol, plays an important role in regulating immune responses and improves MS by modulating the immune system. The optimum level of calcium in the body with vitamin D modulates immune responses and calcium as an essential ion in the body plays a key role in the treatment of autoimmune diseases. The interaction between vitamin D and sex hormones has protective and therapeutic effects against MS and functional synergy between estrogen and calcitriol occurs in disease recovery. Moreover, vitamin D and calcium interact with each other to regulate the immune system and shift them to anti-inflammatory responses.

The Impact of Aging on Multiple Sclerosis

PURPOSE OF REVIEW

Multiple sclerosis (MS) is a chronic, immune-mediated demyelinating disorder of the central nervous system. Age is one of the most important factors in determining MS phenotype. This review provides an overview of how age influences MS clinical characteristics, pathology, and treatment.

RECENT FINDINGS

New methods for measuring aging have improved our understanding of the aging process in MS. New studies have characterized the molecular and cellular composition of chronic active or smoldering plaques in MS. These lesions are important contributors to disability progression in MS. These studies highlight the important role of immunosenescence and the innate immune system in sustaining chronic inflammation. Given these changes in immune function, several studies have assessed optimal treatment strategies in aging individuals with MS. MS phenotype is intimately linked with chronologic age and immunosenescence. While there are many unanswered questions, there has been much progress in understanding this relationship which may lead to more effective treatments for progressive disease.

Estrogen receptor alpha signaling in dendritic cells modulates autoimmune disease phenotype in mice

Estrogen is a disease-modifying factor in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE) via estrogen receptor alpha (ERα). However, the mechanisms by which ERα signaling contributes to changes in disease pathogenesis have not been completely elucidated. Here, we demonstrate that ERα deletion in dendritic cells (DCs) of mice induces severe neurodegeneration in the central nervous system in a mouse EAE model and resistance to interferon beta (IFNβ), a first-line MS treatment. Estrogen synthesized by extragonadal sources is crucial for controlling disease phenotypes. Mechanistically, activated ERα directly interacts with TRAF3, a TLR4 downstream signaling molecule, to degrade TRAF3 via ubiquitination, resulting in reduced IRF3 nuclear translocation and transcription of membrane lymphotoxin (mLT) and IFNβ components. Diminished ERα signaling in DCs generates neurotoxic effector CD4+ T cells via mLT-lymphotoxin beta receptor (LTβR) signaling. Lymphotoxin beta receptor antagonist abolished EAE disease symptoms in the DC-specific ERα-deficient mice. These findings indicate that estrogen derived from extragonadal sources, such as lymph nodes, controls TRAF3-mediated cytokine production in DCs to modulate the EAE disease phenotype.

Ageing and multiple sclerosis

The factor that is most relevant and strongly associated with the clinical course of multiple sclerosis is chronological age. Very young patients exclusively have relapsing remitting disease, whereas those with later onset disease face a more rapid development of permanent disability. For people with progressive multiple sclerosis, the poor response to current disease modifying therapies might be related to ageing in the immune system and CNS. Ageing is also associated with increased risks of side-effects caused by some multiple sclerosis therapies. Both somatic and reproductive ageing processes might contribute to development of progressive multiple sclerosis. Understanding the role of ageing in immune and neural cell function in patients with multiple sclerosis might be key to halting non-relapse-related progression. The growing literature on potential therapies that target senescent cells and ageing processes might provide effective strategies for remyelination and neuroprotection.

Effects of biological sex and pregnancy in experimental autoimmune encephalomyelitis: It's complicated

Experimental autoimmune encephalomyelitis (EAE) can be induced in many animal strains by inoculation with central nervous system antigens and adjuvant or by the passive transfer of lymphocytes reactive with these antigens and is widely used as an animal model for multiple sclerosis (MS). There are reports that female sex and pregnancy affect EAE. Here we review the effects of biological sex and the effects of pregnancy on the clinical features (including disease susceptibility) and pathophysiology of EAE. We also review reports of the possible mechanisms underlying these differences. These include sex-related differences in the immune system and in the central nervous system, the effects of hormones and the sex chromosomes and molecules unique to pregnancy. We also review sex differences in the response to factors that can modify the course of EAE. Our conclusion is that the effects of biological sex in EAE vary amongst animal models and should not be widely extrapolated. In EAE, it is therefore essential that studies looking at the effects of biological sex or pregnancy give full information about the model that is used (i.e. animal strain, sex, the inducing antigen, timing of EAE induction in relation to pregnancy, etc.). In addition, it would be preferable if more than one EAE model were used, to show if any observed effects are generalizable. This is clearly a field that requires further work. However, understanding of the mechanisms of sex differences could lead to greater understanding of EAE, and suggest possible therapies for MS.

Thermoregulatory dynamics reveal sex-specific inflammatory responses to experimental autoimmune encephalomyelitis in mice: Implications for multiple sclerosis-induced fatigue in females

The course of multiple sclerosis (MS) is characterized by striking sex differences in symptoms such as fatigue and impaired thermal regulation, which are associated with aggravated systemic pro-inflammatory processes. The purpose of this study was to replicate these symptoms in experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice in the quest to advance the preclinical study of non-motor symptoms of MS. Male and female C57BL/6 mice exposed to a mild form of EAE were evaluated for the progression of clinical, behavioural, thermal, and inflammatory processes. We show higher susceptibility in females to EAE than males based on greater clinical score and cumulative disease index (CDI), fatigue-like and anxiety-like behaviours. Accordingly, infrared (IR) thermography indicated higher cutaneous temperatures in females from post-induction days 12-23. Females also responded to EAE with greater splenic and adrenal gland weights than males as well as sex-specific changes in pro- and anti-inflammatory cytokines. These findings provide the first evidence of a sex-specific thermal response to immune-mediated demyelination, thus proposing a non-invasive assessment approach of the psychophysiological dynamics in EAE mice. The results are discussed in relation to the thermoregulatory correlates of fatigue and how endogenously elevated body temperature without direct heat exposure may be linked to psychomotor inhibition in patients with MS.

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

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

Cystatin C Plays a Sex-Dependent Detrimental Role in Experimental Autoimmune Encephalomyelitis

The cysteine protease inhibitor Cystatin C (CST3) is highly expressed in the brains of multiple sclerosis (MS) patients and C57BL/6J mice with experimental autoimmune encephalomyelitis (EAE; a model of MS), but its roles in the diseases are unknown. Here, we show that CST3 plays a detrimental function in myelin oligodendrocyte glycoprotein 35–55 (MOG_35–55)-induced EAE but only in female animals. Female Cst3 null mice display significantly lower clinical signs of disease compared to wild-type (WT) littermates. This difference is associated with reduced interleukin-6 production and lower expression of key proteins (CD80, CD86, major histocompatibility complex [MHC] II, LC3A/B) involved in antigen processing, presentation, and co-stimulation in antigen-presenting cells (APCs). In contrast, male WT and Cst3^−/− mice and cells show no differences in EAE signs or APC function. Further, the sex-dependent effect of CST3 in EAE is sensitive to gonadal hormones. Altogether, we have shown that CST3 has a sex-dependent role in MOG_35–55-induced EAE.

Cystatin C (CST3) is increased in the brains of multiple sclerosis patients, but its role is unknown. In a mouse model of the disease, Hoghooghi et al. find that CST3 has a detrimental function but only in female animals. The effect is related to activation of antigen-presenting cells of the immune system.

Animal Models of Multiple Sclerosis

Animal models with high translational validity are essential tools in understanding disease pathogenesis and in the development of therapeutic strategies. Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system characterized by progressive neurological deficits and socioeconomic burden. Experimental autoimmune encephalomyelitis (EAE) is the most extensively utilized animal model of MS, with well-characterized rodent and non-human primate variants. The EAE model is typically induced by either active immunization with myelin-derived proteins or peptides in adjuvant or by passive transfer of activated myelin-specific CD4⁺ T lymphocytes. To date, the EAE model has been an essential tool in the development of at least seven U.S. Food and Drug Administration (FDA)-approved immunomodulatory drugs for the treatment of MS, including glatiramer acetate, fingolimod, and natalizumab. However, the translational validity of the EAE model is frequently compromised due to poor study design, inconsistent clinical scoring endpoints, and inappropriate statistical calculations. No single animal model accurately reflects the complexity of human MS pathogenesis. Beyond EAE, multiple additional animal models are described, including Theiler's murine encephalomyelitis virus and cuprizone-induced demyelination, which facilitate the study of pathogen-induced CNS autoimmunity and remyelination, respectively. This overview summarizes several of the most frequently used animal models of MS and highlights key factors that significantly influence the experimental outcome and affect translational validity. © 2021 Wiley Periodicals LLC.

In-depth quantitative proteomic characterization of organotypic hippocampal slice culture reveals sex-specific differences in biochemical pathways

Sex differences in the brain of mammals range from neuroarchitecture through cognition to cellular metabolism. The hippocampus, a structure mostly associated with learning and memory, presents high vulnerability to neurodegeneration and aging. Therefore, we explored basal sex-related differences in the proteome of organotypic hippocampal slice culture, a major in vitro model for studying the cellular and molecular mechanisms related to neurodegenerative disorders. Results suggest a greater prevalence of astrocytic metabolism in females and significant neuronal metabolism in males. The preference for glucose use in glycolysis, pentose phosphate pathway and glycogen metabolism in females and high abundance of mitochondrial respiration subunits in males support this idea. An overall upregulation of lipid metabolism was observed in females. Upregulation of proteins responsible for neuronal glutamate and GABA synthesis, along with synaptic associated proteins, were observed in males. In general, the significant spectrum of pathways known to predominate in neurons or astrocytes, together with the well-known neuronal and glial markers observed, revealed sex-specific metabolic differences in the hippocampus. TEM qualitative analysis might indicate a greater presence of mitochondria at CA1 synapses in females. These findings are crucial to a better understanding of how sex chromosomes can influence the physiology of cultured hippocampal slices and allow us to gain insights into distinct responses of males and females on neurological diseases that present a sex-biased incidence.

Estriol in regulation of cell-mediated immune reactions in multiple sclerosis

The effect of pregnancy hormone estriol (E₃) on innate and adaptive immunity cells functions in patients with multiple sclerosis (MS) in comparison with healthy donors (HD) was studied. E₃ inhibited phagocytic activity of neutrophils and enhanced monocytes IDO activity. Treg percentage increased and number of Th17 and iNKT cells decreased under E₃ influence. At the same time, E₃ stimulated production of IL-10 and inhibited secretion of IL-17. The hormonal effects were realized on the cells of both HD and MS patients. Thus, the MS amelioration during pregnancy may be related to E₃ influence.

Relapsing and progressive MS: the sex-specific perspective

Background:

Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease whose aetiology is not fully understood. The female sex is clearly predominant, with a sex ratio between 2 and 3. In primary progressive MS the sex ratio almost balances out. Since the age at onset is higher for patients with progressive onset (POMS) than for relapsing onset (ROMS), it can be hypothesized that the age at onset is a decisive factor for the sex ratio.

Methods:

To address this aspect, we compare clinical and demographic data between females and males for the different disease courses within the population of the German MS Register by the German MS Society. Only patients with complete details in mandatory data items and a follow-up visit since 01. Jan 2018 were included.

Results:

A total of 18,728 patients were included in our analyses, revealing a female-to-male ratio of 2.6 (2.7 for patients with ROMS and 1.3 for POMS). The age at diagnosis is higher in patients with POMS (43.3 and 42.3 years for females and males versus 32.1 and 33.2 years, respectively). Females irrespective of disease course are statistically significantly more often affected by cognitive impairment (POMS: p = 0.013, ROMS: p = 0.001) and depression (POMS: p = 0.002, ROMS: 0.001) and suffer more often from pain (POMS and ROMS: p < 0.001). Fatigue is significantly more often seen in females with ROMS (p < 0.001) but not in POMS. Females with ROMS retire significantly (p < 0.001) earlier (42.8 versus 44.2 years) and to a greater extent than males (28 versus 24%). Disease progression was similar for women and men.

Conclusion:

Our analysis shows that clinical and demographic data differ more between disease courses than between men and women. For pain, depression and cognitive impairment the female sex is the decisive factor. Whether these factors are responsible for the earlier retirement of females with ROMS is not clear. Appropriate measures for optimization of symptomatic treatment as well as to promote employment should be taken.

An Inconvenient Variable: Sex Hormones and Their Impact on T Cell Responses

Epidemiologic data demonstrate sex differences in autoimmune diseases, immune responses against infection, and antitumor immunity, and accumulating evidence suggests a major role for sex hormones in mediating these differences. In this study, we review recent advances in understanding how sex hormones regulate T cell responses to alter susceptibility to autoimmunity. Although sex hormones can directly alter gene transcriptional programs of T cells, we focus in this study on how sex hormones alter T cell development and function through their effects on thymic stromal cells and innate cell types. In addition to contributing to our understanding of sex differences, these findings also have implications for the therapeutic use of sex hormones and sex hormone modulators, which are now being prescribed to increasing numbers of patients for a wide variety of indications.

The role of testosterone in MS risk and course

There is significant animal model data demonstrating a benefit of testosterone on both inflammatory and neuroprotective mechanisms relevant to multiple sclerosis (MS). Several studies have demonstrated lowered testosterone levels in up to 40% of men with MS. Lower testosterone levels were correlated with worsened scores of physical and cognitive disability. There is increasing data suggesting a role of testosterone in MS risk. A pilot study has demonstrated significant benefits of testosterone replacement therapy on cognitive, radiological, and immunological outcome measures in men with MS. Larger studies in other conditions have demonstrated concerns in terms of cardiovascular risk, which indicate the need for careful monitoring upon administration to MS patients. Further studies are needed to develop safer testosterone preparations, which preserve its multiple beneficial effects, as well as multicenter clinical trials to evaluate safety, dosing, and efficacy in larger populations of men with MS. Additionally, studies are needed to further explore the role of androgens as a risk factor for MS, particularly at key life transitions.

Mode of Action of Aspirin in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic and debilitating autoimmune disorder of the central nervous system in which the autoimmune T cells destroy myelin, thus causing lesion, damage, and neuronal dysfunction. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS that is particularly useful for testing new therapeutic approaches against MS. Aspirin (acetyl salicylic acid) is one of the oldest and widely used medicines in the world, and recently it has been shown that low-dose aspirin is capable of suppressing the disease process of EAE in mice. One of the root causes of this autoimmune disease process is the decrease and/or suppression of Foxp3-expressing anti-autoimmune regulatory T cells (Tregs) and associated increase in autoimmune T-helper 1 (Th1) and Th17 cells. Aspirin upregulates Tregs and decreases Th1 and Th17 responses. Accordingly, the suppression of Tregs abrogates the protective effect of aspirin on EAE, indicating that aspirin protects EAE via Tregs. While there are several mechanisms for the maintenance of Tregs under immune insults, aspirin increases the level of interleukin-11 (IL-11), an immunomodulatory cytokine, and IL-11 alone is sufficient to protect Tregs. Being a multifunctional molecule, aspirin stimulates the activation of cAMP-response element-binding (CREB) to promote the recruitment of CREB to the IL-11 gene promoter and stimulate the transcription of IL-11 in splenocytes. Therefore, it appears that low-dose aspirin protects EAE via CREB-mediated stimulation of IL-11-Treg pathway and that aspirin may have therapeutic importance in MS.

The impact of early-life sub-therapeutic antibiotic treatment (STAT) on excessive weight is robust despite transfer of intestinal microbes

The high-fat, high-calorie diets of westernized cultures contribute to the global obesity epidemic, and early life exposure to antibiotics may potentiate those dietary effects. Previous experiments with mice had shown that sub-therapeutic antibiotic treatment (STAT)-even restricted to early life-affected the gut microbiota, altered host metabolism, and increased adiposity throughout the lifetime of the animals. Here we carried out a large-scale cohousing experiment to investigate whether cohousing STAT and untreated (Control) mice would transfer the STAT-perturbed microbiota and transmit its impact on weight. We exposed pregnant dams and their young offspring to either low-dose penicillin (STAT) or water (Control) until weaning, and then followed the offspring as they grew and endured a switch from normal to high-fat diet at week 17 of life. Cohousing, which started at week 4, rapidly approximated the microbiota within cages, lowering the weight of STAT mice relative to non-cohoused mice. The effect, however, varied between cages, and was restricted to the first 16 weeks when diet consisted of normal chow. Once mice switched to high-fat diet, the microbiota α- and β-diversity expanded and the effect of cohousing faded: STAT mice, again, were heavier than control mice independently of cohousing. Metabolomics revealed serum metabolites associated with STAT exposure, but no significant differences were detected in glucose or insulin tolerance. Our results show that cohousing can partly ameliorate the impact of STAT on the gut microbiota but not prevent increased weight with high-fat diet. These observations have implications for microbiota therapies aimed to resolve the collateral damage of antibiotics and their load on human obesity.

Clonal Glial Response in a Multiple Sclerosis Mouse Model

Multiple sclerosis (MS) is an autoimmune disease causing central nervous system (CNS) demyelination and axonal injury. In the last years the importance of astrocytes in MS is rapidly increasing, recognizing astrocytes as highly active players in MS pathogenesis. Usually the role assigned to astrocytes in MS lesions has been the formation of the glial scar, but now their implication during lesion formation and the immune response increasingly recognized. Since astrocytes are a heterogeneous cell population with diverse roles in the CNS, the aim of this study was to analyze the putative clonal response of astrocytes in a demyelinating scenario. To undertake this aim, we used the induced experimental autoimmune encephalomyelitis (EAE) as a murine model for MS in previously electroporated mice with in vivo multicolor lineage tracing system, the StarTrack methodology. Our data revealed a variety of morphological changes that were different among distinct clones. In many cases, cells of the same clone responded equally to the injury, while in other cases clonally-related cells responded differently to the injury. Therefore, whereas some clones exhibited a strong morphological alteration, other clones located at similar distances to the lesion were apparently unresponsive. Thus, at present there is no compelling evidences that clonal relationship influences the position or function of astrocytes in the EAE model. Further, the coexistence of different astroglial clonal responses to the bran injury reveals the significance of development to determine the astrocyte features that respond to brain injuries.

Further Evidence on Efficacy of Diet Supplementation with Fatty Acids in Ocular Pathologies: Insights from the EAE Model of Optic Neuritis

In the experimental autoimmune encephalomyelitis (EAE) mouse model of optic neuritis, we recently demonstrated that diet supplementation with a balanced mixture of fatty acids (FAs), including omega 3 and omega 6, efficiently limited inflammatory events in the retina and prevented retinal ganglion cell (RGC) death, although mechanisms underlying the efficacy of FAs were to be elucidated. Whether FAs effectiveness was accompanied by efficient rescue of demyelinating events in the optic nerve was also unresolved. Finally, the possibility that RGC rescue might result in ameliorated visual performance remained to be investigated. Here, the EAE model of optic neuritis was used to investigate mechanisms underlying the anti-inflammatory effects of FAs, including their potential efficacy on macrophage polarization. In addition, we determined how FAs-induced rescue of RGC degeneration was related to optic nerve histopathology by performing ultrastructural morphometric analysis with transmission electron microscopy. Finally, RGC rescue was correlated with visual performance by recording photopic electroretinogram, an efficient methodology to unravel the role of RGCs in the generation of electroretinographic waves. We conclude that the ameliorative effects of FAs were dependent on a predominant anti-inflammatory action including a role on promoting the shift of macrophages from the inflammatory M1 phenotype towards the anti-inflammatory M2 phenotype. This would finally result in restored optic nerve histopathology and ameliorated visual performance. These findings can now offer new perspectives for implementing our knowledge on the effectiveness of diet supplementation in counteracting optic neuritis and suggest the importance of FAs as possible adjuvants in therapies against inflammatory diseases of the eye.

Fatty Acids Dietary Supplements Exert Anti-Inflammatory Action and Limit Ganglion Cell Degeneration in the Retina of the EAE Mouse Model of Multiple Sclerosis

Optic neuritis is an acute inflammatory demyelinating disorder of the optic nerve (ON) and is an initial symptom of multiple sclerosis (MS). Optic neuritis is characterized by ON degeneration and retinal ganglion cell (RGC) loss that contributes to permanent visual disability and lacks a reliable treatment. Here, we used the experimental autoimmune encephalomyelitis (EAE) mouse model of MS, a well-established model also for optic neuritis. In this model, C57BL6 mice, intraperitoneally injected with a fragment of the myelin oligodendrocyte glycoprotein (MOG), were found to develop inflammation, Müller cell gliosis, and infiltration of macrophages with increased production of oncomodulin (OCM), a calcium binding protein that acts as an atypical trophic factor for neurons enabling RGC axon regeneration. Immunolabeling of retinal whole mounts with a Brn3a antibody demonstrated drastic RGC loss. Dietary supplementation with Neuro-FAG (nFAG^®), a balanced mixture of fatty acids (FAs), counteracted inflammatory and gliotic processes in the retina. In contrast, infiltration of macrophages and their production of OCM remained at elevated levels thus eventually preserving OCM trophic activity. In addition, the diet supplement with nFAG exerted a neuroprotective effect preventing MOG-induced RGC death. In conclusion, these data suggest that the balanced mixture of FAs may represent a useful form of diet supplementation to limit inflammatory events and death of RGCs associated to optic neuritis. This would occur without affecting macrophage infiltration and the release of OCM thus favoring the maintenance of OCM neuroprotective role.

Activating transcription factor 6α deficiency exacerbates oligodendrocyte death and myelin damage in immune-mediated demyelinating diseases

Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) play a critical role in immune-mediated demyelinating diseases, including multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), by regulating the viability of oligodendrocytes. Our previous studies show that activation of the PERK branch of the UPR protects myelinating oligodendrocytes against ER stress in young, developing mice that express IFN-γ, a key pro-inflammatory cytokine in MS and EAE, in the CNS. Several studies also demonstrate that PERK activation preserves oligodendrocyte viability and function, protecting mice against EAE. While evidence suggests activation of the ATF6α branch of the UPR in oligodendrocytes under normal and disease conditions, the effects of ATF6α activation on oligodendrocytes in immune-mediated demyelinating diseases remain unknown. Herein, we showed that ATF6α deficiency had no effect on oligodendrocytes under normal conditions. Interestingly, we showed that ATF6α deficiency exacerbated ER stressed-induced myelinating oligodendrocyte death and subsequent myelin loss in the developing CNS of IFN-γ-expressing mice. Moreover, we found that ATF6α deficiency increased EAE severity and aggravated EAE-induced oligodendrocyte loss and demyelination, without affecting inflammation. Thus, these data suggest the protective effects of ATF6α activation on oligodendrocytes in immune-mediated demyelinating diseases.

The importance of studying sex differences in disease: The example of multiple sclerosis

To date, scientific research has often focused on one sex, with assumptions that study of the other sex would yield similar results. However, many diseases affect males and females differently. The sex of a patient can affect the risk for both disease susceptibility and progression. Such differences can be brought to the laboratory bench to be investigated, potentially bringing new treatments back to the clinic. This method of research, known as a "bedside to bench to bedside" approach, has been applied to studying sex differences in multiple sclerosis (MS). Females have greater susceptibly to MS, while males have worse disease progression. These two characteristics of the disease are influenced by the immune system and the nervous system, respectively. Thus, sex differences in each system must be studied. Personalized medicine has been at the forefront of research recently, and studying sex differences in disease fits with this initiative. This review will discuss the known sex differences in MS and highlight how investigating them can lead to new insights and potential treatments for both men and women. © 2016 Wiley Periodicals, Inc.

The stability of the transcriptome during the estrous cycle in four regions of the mouse brain

We analyzed the transcriptome of the C57BL/6J mouse hypothalamus, hippocampus, neocortex, and cerebellum to determine estrous cycle-specific changes in these four brain regions. We found almost 16,000 genes are present in one or more of the brain areas but only 210 genes, ∼1.3%, are significantly changed as a result of the estrous cycle. The hippocampus has the largest number of differentially expressed genes (DEGs) (82), followed by the neocortex (76), hypothalamus (63), and cerebellum (26). Most of these DEGs (186/210) are differentially expressed in only one of the four brain regions. A key finding is the unique expression pattern of growth hormone (Gh) and prolactin (Prl). Gh and Prl are the only DEGs to be expressed during only one stage of the estrous cycle (metestrus). To gain insight into the function of the DEGs, we examined gene ontology and phenotype enrichment and found significant enrichment for genes associated with myelination, hormone stimulus, and abnormal hormone levels. Additionally, 61 of the 210 DEGs are known to change in response to estrogen in the brain. 50 of the 210 genes differentially expressed as a result of the estrous cycle are related to myelin and oligodendrocytes and 12 of the 63 DEGs in the hypothalamus are oligodendrocyte- and myelin-specific genes. This transcriptomic analysis reveals that gene expression in the female mouse brain is remarkably stable during the estrous cycle and demonstrates that the genes that do fluctuate are functionally related.

Systems Genetic Analysis in GeneNetwork.org

Genome-wide association studies (GWAS) have emerged as a powerful tool to identify alleles and molecular pathways that influence susceptibility to psychiatric disorders and other diseases. Forward genetics using mouse mapping populations allows for a complementary approach that provides rigorous genetic and environmental control. In this unit, we describe techniques and tools that reduce the technical burden traditionally associated with genetic mapping in mice and enhance their translational utility to human psychiatric disorders. We provide guidance on choosing the appropriate mapping population, discuss the importance of phenotype, and offer detailed instructions on using the Web-based resource GeneNetwork to aid neuroscientists in better understanding the mechanisms through which genes influence behavior. We believe that the continued development of mouse mapping populations, genetic tools, bioinformatics resources, and statistical methodologies should remain a parallel strategy by which to investigate the genetic and environmental underpinnings of psychiatric disorders and other diseases in humans. © 2017 by John Wiley & Sons, Inc.

Glucocorticoid receptor in T cells mediates protection from autoimmunity in pregnancy

Pregnancy is one of the strongest inducers of immunological tolerance. Disease activity of many autoimmune diseases including multiple sclerosis (MS) is temporarily suppressed by pregnancy, but little is known about the underlying molecular mechanisms. Here, we investigated the endocrine regulation of conventional and regulatory T cells (Tregs) during reproduction. In vitro, we found the pregnancy hormone progesterone to robustly increase Treg frequencies via promiscuous binding to the glucocorticoid receptor (GR) in T cells. In vivo, T-cell-specific GR deletion in pregnant animals undergoing experimental autoimmune encephalomyelitis (EAE), the animal model of MS, resulted in a reduced Treg increase and a selective loss of pregnancy-induced protection, whereas reproductive success was unaffected. Our data imply that steroid hormones can shift the immunological balance in favor of Tregs via differential engagement of the GR in T cells. This newly defined mechanism confers protection from autoimmunity during pregnancy and represents a potential target for future therapy.

Distinct effects of obesity and puberty on risk and age at onset of pediatric MS

Objective

The aim of this study was to examine the relative contributions of body mass index (BMI) and pubertal measures for risk and age of onset of pediatric MS.

Methods

Case–control study of 254 (63% female) MS cases (onset<18 years of age) and 420 (49% female) controls conducted at 14 U.S. Pediatric MS Centers. Sex‐ and age‐stratified BMI percentiles were calculated using CDC growth charts from height and weight measured at enrollment for controls, and within 1 year of onset for MS cases. Sex‐stratified associations between MS risk and age at symptom onset with both BMI and pubertal factors were estimated controlling for race and ethnicity.

Results

Only 11% of girls and 15% of boys were prepubertal (Tanner stage I) at MS onset. 80% of girls had onset of MS after menarche. BMI percentiles were higher in MS cases versus controls (girls: P < 0.001; boys: P = 0.018). BMI was associated with odds of MS in multivariate models in postpubertal girls (OR = 1.60, 95% confidence interval [CI]: 1.12, 2.27, P = 0.009) and boys (OR = 1.43, 95% CI: 1.08, 1.88, P = 0.011). In girls with MS onset after menarche, higher BMI was associated with younger age at first symptoms (P = 0.031). Younger menarche was associated with stronger effects of BMI through mediation and interaction analysis. In pubertal/postpubertal boys, 89% of whom were obese/overweight, earlier sexual maturity was associated with earlier onset of MS (P < 0.001).

Interpretation

Higher BMI in early adolescence is a risk factor for MS in girls and boys. Earlier age at sexual maturity contributes to earlier age at MS onset, particularly in association with obesity.

Protective Effects on Central Nervous System by Acidic Polysaccharide of Panax ginseng in Relapse-Remitting Experimental Autoimmune Encephalomyelitis-Induced SJL/J Mice

Bearing pathologic and clinical similarities to human multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE) is used as a murine model to test potential therapeutic agents for MS. Recently, we reported the protective effects of an acidic polysaccharide of Panax ginseng (APG) in C57BL/6 strain-dependent EAE, a model of primary progressive MS. In this study, we extend our previous findings on the therapeutic capacity of APG in relapsing-remitting EAE (rr-EAE), the animal model to closely mimic recurrent inflammatory demyelination lesions of relapsing-remitting MS. Treatments with APG led to a significant reduction of clinical symptoms and the relapse rate of EAE than vehicle treatments. Consistent with this, histological examination revealed that APG markedly modulated the infiltration of CD4[Formula: see text] T cells and CD11b[Formula: see text] macrophages into the spinal cord and the APG-treated CNS was devoid of demyelination and axonal damages. In addition, APG decreased the proliferation of peripheral PLP-reactive T cells and the production of pro-inflammatory factors such as IFN-[Formula: see text], IL-17 and TNF-[Formula: see text]. The fact that APG can induce clinically beneficial effects to distinct types of EAE furthers our understanding on the basis of its immunosuppression in EAE and, possibly, in MS. Our results suggest that APG may serve as a new therapeutic agent for MS as well as other human autoimmune diseases, and warrants continued evaluation for its translation into therapeutic application.

Large Scale Gene Expression Meta-Analysis Reveals Tissue-Specific, Sex-Biased Gene Expression in Humans

The severity and prevalence of many diseases are known to differ between the sexes. Organ specific sex-biased gene expression may underpin these and other sexually dimorphic traits. To further our understanding of sex differences in transcriptional regulation, we performed meta-analyses of sex biased gene expression in multiple human tissues. We analyzed 22 publicly available human gene expression microarray data sets including over 2500 samples from 15 different tissues and 9 different organs. Briefly, by using an inverse-variance method we determined the effect size difference of gene expression between males and females. We found the greatest sex differences in gene expression in the brain, specifically in the anterior cingulate cortex, (1818 genes), followed by the heart (375 genes), kidney (224 genes), colon (218 genes), and thyroid (163 genes). More interestingly, we found different parts of the brain with varying numbers and identity of sex-biased genes, indicating that specific cortical regions may influence sexually dimorphic traits. The majority of sex-biased genes in other tissues such as the bladder, liver, lungs, and pancreas were on the sex chromosomes or involved in sex hormone production. On average in each tissue, 32% of autosomal genes that were expressed in a sex-biased fashion contained androgen or estrogen hormone response elements. Interestingly, across all tissues, we found approximately two-thirds of autosomal genes that were sex-biased were not under direct influence of sex hormones. To our knowledge this is the largest analysis of sex-biased gene expression in human tissues to date. We identified many sex-biased genes that were not under the direct influence of sex chromosome genes or sex hormones. These may provide targets for future development of sex-specific treatments for diseases.

Tamoxifen accelerates the repair of demyelinated lesions in the central nervous system

Enhancing central nervous system (CNS) myelin regeneration is recognized as an important strategy to ameliorate the devastating consequences of demyelinating diseases such as multiple sclerosis. Previous findings have indicated that myelin proteins, which accumulate following demyelination, inhibit remyelination by blocking the differentiation of rat oligodendrocyte progenitor cells (OPCs) via modulation of PKCα. We therefore screened drugs for their potential to overcome this differentiation block. From our screening, tamoxifen emerges as a potent inducer of OPC differentiation in vitro. We show that the effects of tamoxifen rely on modulation of the estrogen receptors ERα, ERβ, and GPR30. Furthermore, we demonstrate that administration of tamoxifen to demyelinated rats in vivo accelerates remyelination. Tamoxifen is a well-established drug and is thus a promising candidate for a drug to regenerate myelin, as it will not require extensive safety testing. In addition, Tamoxifen plays an important role in biomedical research as an activator of inducible genetic models. Our results highlight the importance of appropriate controls when using such models.

The influence of sex hormones on cytokines in multiple sclerosis and experimental autoimmune encephalomyelitis: a review

The female predominance of multiple sclerosis (MS) has suggested that hormonal differences between the sexes must confer some protective effect on males or enhance the susceptibility of females to this disease. There has been evidence that gonadal hormones can modulate the immune response regulated by antigen presenting cells and T cells. These cells control the immune response by the production of interacting pro- and anti-inflammatory cytokines. The first include the acute phase pro-inflammatory cytokines of the innate immune response as well as the T-helper 1 (Th1) cytokines, while the later contain the Th2 cytokines as well as the suppressor cytokines. There is some evidence that MS and experimental autoimmune encephalitis (EAE) are Th1 cell-mediated diseases. For this reason many studies have been done to influence the pro-inflammatory cytokine production of these Th1 cells in favour of an anti-inflammatory immune response as mediated by Th2 cells. However the role of the regulatory T cells in this context is not clearly understood. Here we review the studies concerning the role of sex hormones on the cytokine production in relation to the disease course of MS and EAE and in particular in the light of the recent revival of the regulatory T cells and their suppressive cytokines.

Effect of methacrylic acid beads on the sonic hedgehog signaling pathway and macrophage polarization in a subcutaneous injection mouse model

Poly(methacrylic acid-co-methyl methacrylate) (MAA) beads promote a vascular regenerative response when used in diabetic wound healing. Previous studies reported that MAA beads modulated the expression of sonic hedgehog (Shh) and inflammation related genes in diabetic wounds. The aim of this work was to follow up on these observations in a subcutaneous injection model to study the host response in the absence of the confounding factors of diabetic wound healing. In this model, MAA beads improved vascularization in healthy mice of both sexes compared to control poly(methyl methacrylate) (MM) beads, with a stronger effect seen in males than females. MAA-induced vessels were perfusable, as evidenced from the CLARITY-processed images. In Shh-Cre-eGFP/Ptch1-LacZ non-diabetic transgenic mice, the increased vessel formation was accompanied by a higher density of cells expressing GFP (Shh) and β-Gal (patched 1, Ptch1) suggesting MAA enhanced the activation of the Shh pathway. Ptch1 is the Shh receptor and a target of the pathway. MAA beads also modulated the inflammatory cell infiltrate in CD1 mice: more neutrophils and more macrophages were noted with MAA relative to MM beads at days 1 and 7, respectively. In addition, MAA beads biased macrophages towards a MHCII-CD206+ ("M2") polarization state. This study suggests that the Shh pathway and an altered inflammatory response are two elements of the complex mechanism whereby MAA-based biomaterials effect vascular regeneration.

Male rats develop more severe experimental autoimmune encephalomyelitis than female rats: sexual dimorphism and diergism at the spinal cord level

Compared with females, male Dark Agouti (DA) rats immunized for experimental autoimmune encephalomyelitis (EAE) with rat spinal cord homogenate in complete Freund's adjuvant (CFA) exhibited lower incidence of the disease, but the maximal neurological deficit was greater in the animals that developed the disease. Consistently, at the peak of the disease greater number of reactivated CD4+CD134+CD45RC- T lymphocytes was retrieved from male rat spinal cord. Their microglia/macrophages were more activated and produced greater amount of prototypic proinflammatory cytokines in vitro. Additionally, oppositely to the expression of mRNAs for IL-12/p35, IL-10 and IL-27/p28, the expression of mRNA for IL-23/p19 was upregulated in male rat spinal cord mononuclear cells. Consequently, the IL-17+:IFN-γ+ cell ratio within T lymphocytes from their spinal cord was skewed towards IL-17+ cells. Within this subpopulation, the IL-17+IFN-γ+:IL-17+IL-10+ cell ratio was shifted towards IL-17+IFN-γ+ cells, which have prominent tissue damaging capacity. This was associated with an upregulated expression of mRNAs for IL-1β and IL-6, but downregulated TGF-β mRNA expression in male rat spinal cord mononuclear cells. The enhanced GM-CSF mRNA expression in these cells supported the greater pathogenicity of IL-17+ T lymphocytes infiltrating male spinal cord. In the inductive phase of the disease, contrary to the draining lymph node, in the spinal cord the frequency of CD134+ cells among CD4+ T lymphocytes and the frequency of IL-17+ cells among T lymphocytes were greater in male than in female rats. This most likely reflected an enhanced transmigration of mononuclear cells into the spinal cord (judging by the lesser spinal cord CXCL12 mRNA expression), the greater frequency of activated microglia/macrophages and the increased expression of mRNAs for Th17 polarizing cytokines in male rat spinal cord mononuclear cells. Collectively, the results showed cellular and molecular mechanisms underlying the target organ specific sexual dimorphism in the T lymphocyte-dependent immune/inflammatory response, and suggested a substantial role for the target organ in shaping the sexually dimorphic clinical outcome of EAE.

Association of sex hormones and glucose metabolism with the severity of multiple sclerosis

PURPOSE/AIM OF THE STUDY

We evaluated possible associations between the severity of multiple sclerosis (MS) and levels of sex hormones as well as biochemical parameters in a sample of ambulatory patients.

MATERIAL AND METHODS

This cross-sectional study recruited 133 adults (52 men, 66 premenopausal and 15 postmenopausal women), with relapsing-remitting MS. Fasting venous blood samples were drawn for biochemical and hormonal evaluation. These parameters were tested for possible associations with MS severity, assessed using the Expanded Disability Status Scale (EDSS)-scores.

RESULTS

Follicle-stimulating hormone correlated with mean EDSS scores (r = -0.369, p = 0.038) in the premenopausal subgroup. However, this association became non-significant in the age-adjusted multivariate analysis (p = 0.141; power = 67%, type α error 0.10). Free androgen exhibited a borderline negative effect on EDSS-scores in the subgroup of men (r = -0.367, p = 0.093), which was lost after adjusting for age and duration of disease (p = 0.192; statistical power = 93%, type α error 0.05). Levels of estradiol tended to affect disability status of postmenopausal women (normal-mild vs. severe impairment: 23.33 ± 11.73pg/mL vs. 14.74 ± 6.30pg/mL, p = 0.095). Levels of sex hormones or indices of glycemic metabolism did not differ between patients presenting with EDSS scores higher or lower than the median value.

CONCLUSION

Sex hormones and indices of glucose metabolism exhibited only a middle effect on EDSS scoring, which was not independent from the presence of confounders like age and duration of MS. The present study highlights the need for additional research, in order to elucidate the role of sex hormones and insulin resistance in the course of MS.

Sexual dimorphism in the aged rat CD4+ T lymphocyte-mediated immune response elicited by inoculation with spinal cord homogenate

Considering the crucial pathogenic role of CD4+ T cells in experimental autoimmune encephalomyelitis (EAE) and the opposite direction of the sexual dimorphism in the severity of the disease in 22-24-and 3-month-old dark agouti rats, sex differences in CD4+ T-cell-mediated immune response in aged rats immunized for EAE were examined and compared with those in young animals. In the inductive phase of EAE, fewer activated CD4+ lymphocytes were retrieved from draining lymph nodes of male (developing less severe disease) compared with female rats, due, at least partly, to their lesser expansion. The former reflected a greater suppressive capacity of CD4+CD25+Foxp3+ cells. Consequently, CD4+ lymphocyte infiltration into the spinal cord of aged male rats was diminished. At the peak of EAE, the frequency of reactivated cells was lower, whereas that of the regulatory CD4+ cells was higher in male rat spinal cord. Consistently, microglial activation and the expression of proinflammatory/damaging cytokines in male rat spinal cord mononuclear cells were diminished. Additionally, the frequency of the highly pathogenic IL-17+IFN-γ+ T lymphocytes infiltrating their spinal cord was lower. Together, these results point to (i) an age-specificity in CD4+ cell-mediated immune response and (ii) mechanisms underlying the sex differences in this response in aged rats.

Oral contraceptives combined with interferon β in multiple sclerosis

Objective:

To test the effect of oral contraceptives (OCs) in combination with interferon β (IFN-β) on disease activity in patients with relapsing-remitting multiple sclerosis (RRMS).

Methods:

One hundred fifty women with RRMS were randomized in a 1:1:1 ratio to receive IFN-β-1a subcutaneously (SC) only (group 1), IFN-β-1a SC plus ethinylstradiol 20 μg and desogestrel 150 μg (group 2), or IFN-β-1a SC plus ethinylestradiol 40 μg and desogestrel 125 μg (group 3). The primary endpoint was the cumulative number of combined unique active (CUA) lesions on brain MRI at week 96. Secondary endpoints included MRI and clinical and safety measures.

Results:

The estimated number of cumulative CUA lesions at week 96 was 0.98 (95% confidence interval [CI] 0.81–1.14) in group 1, 0.84 (95% CI 0.66–1.02) in group 2, and 0.72 (95% CI 0.53–0.91) in group 3, with a decrease of 14.1% (p = 0.24) and 26.5% (p = 0.04) when comparing group 1 with groups 2 and 3, respectively. The number of patients with no gadolinium-enhancing lesions was greater in group 3 than in group 1 (p = 0.03). No significant differences were detected in other secondary endpoints. IFN-β or OC discontinuations were equally distributed across groups.

Conclusions:

Our results translate the observations derived from experimental models to patients, supporting the anti-inflammatory effects of OCs with high-dose estrogens, and suggest possible directions for future research.

Classification of evidence:

This study provides Class II evidence that in women with RRMS, IFN-β plus ethinylstradiol and desogestrel decreases the cumulative number of active brain MRI lesions compared with IFN-β alone.

Testosterone Suppresses Hepatic Inflammation by the Downregulation of IL-17, CXCL-9, and CXCL-10 in a Mouse Model of Experimental Acute Cholangitis

Autoimmune liver diseases predominantly affect women. In this study, we aimed to elucidate how sex affects autoimmune hepatic inflammation. Acute experimental cholangitis was induced by adoptive transfer of OVA-specific CD8+ T cells into mice, which express the cognate Ag on cholangiocytes. In contrast to previous mouse models of cholangitis, this model displayed a strong sexual dimorphism: female mice developed marked cholangitis, whereas male mice were resistant to cholangitis induction. The recruitment of endogenous CD4+ T cells, but not transferred CD8+ T cells into female livers was strongly increased. These cells expressed higher amounts of the proinflammatory cytokine IL-17, which was at least in part responsible for the liver inflammation observed. The recruitment of endogenous CD4+ T cells was associated with increased expression of the chemokines CXCL-9 and CXCL-10 in female livers. The sex-specific factor responsible for the observed differences was found to be testosterone: male mice could be rendered susceptible to liver inflammation by castration, and testosterone treatment was sufficient to completely suppress liver inflammation in female mice. Accordingly, testosterone treatment of female mice significantly reduced the expression of IL-17A, CXCL-9, and CXCL-10 within the liver. Serum testosterone levels of untreated mice negatively correlated with the IL-17, CXCL-9, and CXCL-10 expression in the liver, further supporting a role for testosterone in hepatic immune homeostasis. In conclusion, testosterone was found to be the major determinant of the observed sexual dimorphism. Further study into the role of testosterone for liver inflammation could lead to novel treatment targets in human autoimmune liver diseases.

The meninges: new therapeutic targets for multiple sclerosis

The central nervous system (CNS) largely comprises nonregenerating cells, including neurons and myelin-producing oligodendrocytes, which are particularly vulnerable to immune cell-mediated damage. To protect the CNS, mechanisms exist that normally restrict the transit of peripheral immune cells into the brain and spinal cord, conferring an "immune-specialized" status. Thus, there has been a long-standing debate as to how these restrictions are overcome in several inflammatory diseases of the CNS, including multiple sclerosis (MS). In this review, we highlight the role of the meninges, tissues that surround and protect the CNS and enclose the cerebral spinal fluid, in promoting chronic inflammation that leads to neuronal damage. Although the meninges have traditionally been considered structures that provide physical protection for the brain and spinal cord, new data have established these tissues as sites of active immunity. It has been hypothesized that the meninges are important players in normal immunosurveillance of the CNS but also serve as initial sites of anti-myelin immune responses. The resulting robust meningeal inflammation elicits loss of localized blood-brain barrier (BBB) integrity and facilitates a large-scale influx of immune cells into the CNS parenchyma. We propose that targeting the cells and molecules mediating these inflammatory responses within the meninges offers promising therapies for MS that are free from the constraints imposed by the BBB. Importantly, such therapies may avoid the systemic immunosuppression often associated with the existing treatments.

Maternal immune activation in late gestation increases neuroinflammation and aggravates experimental autoimmune encephalomyelitis in the offspring

Multiple sclerosis (MS) is characterized by an autoimmune response against myelin antigens driven by autoreactive T cells. Several lines of evidence indicate that environmental factors, such as previous infection, can influence and trigger autoimmune responses. However, the importance of the gestational period, particularly under inflammatory conditions, on the modulation of MS and related neuroinflammation by the offspring is unknown. This study aimed to evaluate the impact of prenatal exposure to lipopolysaccharide (LPS) during late gestation on the neuroinflammatory response in primary mixed glial cultures and on the progression of experimental autoimmune encephalomyelitis (EAE, an animal model of MS) in the offspring. LPS (Escherichia coli 0127:B8, 120μg/kg) was administered intraperitoneally to pregnant C57BL/6J mice on gestational day 17, and the offspring were assigned to two experiments: (1) mixed glial cultures generated using the brain of neonates, stimulated in vitro with LPS, and (2) adult offspring immunized with MOG35-55. The EAE clinical symptoms were followed for 30days. Different sets of animals were sacrificed either during the onset (7days post-immunization [p.i.]), when spleen and lymph nodes were collected, or the peak of disease (20days p.i.), when CNS were collected for flow cytometry, cytokine production, and protein/mRNA-expression analysis. The primary CNS cultures from the LPS-treated group produced exaggerated amounts of IL-6, IL-1β and nitrites after in vitro stimulus, while IL-10 production was lowered compared to the data of the control group. Prenatal exposure to LPS worsened EAE disease severity in adult offspring, and this worsening was linked to increased CNS-infiltrating macrophages, Th1 cells and Th17 cells at the peak of EAE severity; additionally, exacerbated gliosis was evidenced in microglia (MHC II) and astrocytes (GFAP protein level and immunoreactivity). The IL-2, IL-6 and IL-17 levels in the spleen and lymph nodes were increased in the offspring of the LPS-exposed dams. Our results indicate that maternal immune activation during late gestation predispose the offspring to increased neuroinflammation and potentiate the autoimmune response and clinical manifestation of EAE.

Sex-Based Differences in Multiple Sclerosis (Part I): Biology of Disease Incidence

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease that leads to neuron damage and progressive disability. One major feature of multiple sclerosis (MS) is that it affects women three times more often than men. In this chapter, we overview the evidence that the autoimmune component of MS, which predominates in the early stages of this disease, is more robust in women than in men and undergoes a sharp increase with the onset of puberty. In addition, we discuss the common rodent models of MS that have been used to study the sex-based differences in the development of central nervous system (CNS) autoimmunity. We then address the biological underpinnings of this enhanced MS risk in women by first reviewing the autoimmune mechanisms that are thought to lead to the initiation of this disease and then honing in on how these mechanisms differ between the sexes. Finally, we review what is known about the hormonal and genetic basis of these sex differences in CNS autoimmunity.

Puberty in females enhances the risk of an outcome of multiple sclerosis in children and the development of central nervous system autoimmunity in mice

BACKGROUND

For reasons that remain unclear, three times more women develop multiple sclerosis (MS) than men. This preponderance among women is evident only after 12 years of age, implicating pubertal factors in the risk of MS.

OBJECTIVE

To investigate the influence of female puberty on central nervous system (CNS) autoimmunity.

METHODS

We examined the relationship between age of menarche on MS outcomes in 116 female children (< 16 years old) whom presented with incident 'acquired demyelinating syndromes' (ADS) and were followed prospectively in the national Canadian Pediatric Demyelinating Disease Study, from 2004-2013. Furthermore, we directly investigated the effects of puberty on susceptibility to experimental autoimmune encephalomyelitis (EAE) in two groups of female mice that differed only in their pubertal status.

RESULTS

In the ADS children, a later age of menarche was associated with a decreased risk of subsequent MS diagnosis. This relationship persisted, after accounting for patient age at ADS presentation and the presence of ≥1 T2 lesions on brain magnetic resonance imaging (MRI), with a hazard ratio (HR) of 0.64; and additional factors that associate with MS outcomes in ADS children, including low vitamin D levels. Furthermore, we found female mice that had transitioned through puberty were more susceptible to EAE than age-matched, pre-pubertal mice.

CONCLUSION

Puberty in females enhances CNS autoimmune mechanisms that lead to MS in humans and EAE in mice.

Phenotypic changes in immune cell subsets reflect increased infarct volume in male vs. female mice

Inflammatory responses in the brain after cerebral ischemia have been studied extensively in male mice, but not female mice, thus potentially giving a less-than-accurate view of gender associated pathological processes. In humans, cerebral infarcts are typically smaller in premenopausal females than in age-matched males. In the current study, we confirmed smaller infarcts in female vs. male mice after middle cerebral artery occlusion and 96 h of reperfusion. Moreover, we explored immunological alterations related to this difference and found that the percentage of CD4+ T lymphocytes was significantly higher in spleens in males than females, with increased expression of the activation markers, CD69 and CD44. In contrast, the percentage of CD8+ T lymphocytes was significantly higher in spleens of females than males, leading to the identification of a small but distinct population of IL-10-secreting CD8+CD122+ suppressor T cells that were also increased in females. Finally, we observed that males have a greater percentage of activated macrophages/microglia in the brain than females, as well as increased expression of the VLA-4 adhesion molecule in both brain and spleen. This new information suggesting gender-dependent immunological mechanisms in stroke implies that effective treatments for human stroke may also be gender specific.

Neuroactive steroid levels in plasma and cerebrospinal fluid of male multiple sclerosis patients

Neuroactive steroid family includes molecules synthesized in peripheral glands (i.e., hormonal steroids) and directly in the nervous system (i.e., neurosteroids) which are key regulators of the nervous function. As already reported in clinical and experimental studies, neurodegenerative diseases affect the levels of neuroactive steroids. However, a careful analysis comparing the levels of these molecules in cerebrospinal fluid (CSF) and in plasma of multiple sclerosis (MS) patients is still missing. To this aim, the levels of neuroactive steroids were evaluated by liquid chromatography-tandem mass spectrometry in CSF and plasma of male adults affected by Relapsing-Remitting MS and compared with those collected in control patients. An increase in pregnenolone and isopregnanolone levels associated with a decrease in progesterone metabolites, dihydroprogesterone, and tetrahydroprogesterone was observed in CSF of MS patients. Moreover, an increase of 5α-androstane-3α,17β-diol and of 17β-estradiol levels associated with a decrease of dihydrotestosterone also occurred. In plasma, an increase in pregnenolone, progesterone, and dihydrotestosterone and a decrease in dihydroprogesterone and tetrahydroprogesterone levels were reported. This study shows for the first time that the levels of several neuroactive steroids, and particularly those of progesterone and testosterone metabolites, are deeply affected in CSF of relapsing-remitting MS male patients. We here demonstrated that, the cerebrospinal fluid and plasma levels of several neuroactive steroids are modified in relapsing remitting multiple sclerosis male patients. Interestingly, we reported for the first time that, the levels of progesterone and testosterone metabolites are deeply affected in cerebrospinal fluid. These findings may have an important relevance in therapeutic and/or diagnostic field of multiple sclerosis.

XY sex chromosome complement, compared with XX, in the CNS confers greater neurodegeneration during experimental autoimmune encephalomyelitis

Women are more susceptible to multiple sclerosis (MS) and have more robust immune responses than men. However, men with MS tend to demonstrate a more progressive disease course than women, suggesting a disconnect between the severity of an immune attack and the CNS response to a given immune attack. We have previously shown in an MS model, experimental autoimmune encephalomyelitis, that autoantigen-sensitized XX lymph node cells, compared with XY, are more encephalitogenic. These studies demonstrated an effect of sex chromosomes in the induction of immune responses, but did not address a potential role of sex chromosomes in the CNS response to immune-mediated injury. Here, we examined this possibility using XX versus XY bone marrow chimeras reconstituted with a common immune system of one sex chromosomal type. We found that experimental autoimmune encephalomyelitis mice with an XY sex chromosome complement in the CNS, compared with XX, demonstrated greater clinical disease severity with more neuropathology in the spinal cord, cerebellum, and cerebral cortex. A candidate gene on the X chromosome, toll-like receptor 7, was then examined. Toll-like receptor 7 expression in cortical neurons was higher in mice with XY compared with mice with XX CNS, consistent with the known neurodegenerative role for toll-like receptor 7 in neurons. These results suggest that sex chromosome effects on neurodegeneration in the CNS run counter to effects on immune responses, and may bear relevance to the clinical enigma of greater MS susceptibility in women but faster disability progression in men. This is a demonstration of a direct effect of sex chromosome complement on neurodegeneration in a neurological disease.