Suppression of experimental autoimmune encephalomyelitis using estrogen receptor-selective ligands

Specific and shared biological functions of PARP2 - is PARP2 really a lil' brother of PARP1?

PARP2, that belongs to the family of ADP-ribosyl transferase enzymes (ART), is a discovery of the millennium, as it was identified in 1999. Although PARP2 was described initially as a DNA repair factor, it is now evident that PARP2 partakes in the regulation or execution of multiple biological processes as inflammation, carcinogenesis and cancer progression, metabolism or oxidative stress-related diseases. Hereby, we review the involvement of PARP2 in these processes with the aim of understanding which processes are specific for PARP2, but not for other members of the ART family. A better understanding of the specific functions of PARP2 in all of these biological processes is crucial for the development of new PARP-centred selective therapies.

CD28-signaling can be partially compensated in CD28-knockout mice but is essential for virus elimination in a murine model of multiple sclerosis

The intracerebral infection of mice with Theiler’s murine encephalomyelitis virus (TMEV) represents a well-established animal model for multiple sclerosis (MS). Because CD28 is the main co-stimulatory molecule for the activation of T cells, we wanted to investigate its impact on the course of the virus infection as well as on a potential development of autoimmunity as seen in susceptible mouse strains for TMEV. In the present study, 5 weeks old mice on a C57BL/6 background with conventional or tamoxifen-induced, conditional CD28-knockout were infected intracerebrally with TMEV-BeAn. In the acute phase at 14 days post TMEV-infection (dpi), both CD28-knockout strains showed virus spread within the central nervous system (CNS) as an uncommon finding in C57BL/6 mice, accompanied by histopathological changes such as reduced microglial activation. In addition, the conditional, tamoxifen-induced CD28-knockout was associated with acute clinical deterioration and weight loss, which limited the observation period for this mouse strain to 14 dpi. In the chronic phase (42 and 147 dpi) of TMEV-infection, surprisingly only 33% of conventional CD28-knockout mice showed chronic TMEV-infection with loss of motor function concomitant with increased spinal cord inflammation, characterized by T- and B cell infiltration, microglial activation and astrogliosis at 33-42 dpi. Therefore, the clinical outcome largely depends on the time point of the CD28-knockout during development of the immune system. Whereas a fatal clinical outcome can already be observed in the early phase during TMEV-infection for conditional, tamoxifen-induced CD28-knockout mice, only one third of conventional CD28-knockout mice develop clinical symptoms later, accompanied by ongoing inflammation and an inability to clear the virus. However, the development of autoimmunity could not be observed in this C57BL/6 TMEV model irrespective of the time point of CD28 deletion.

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.

Complement component 3 from astrocytes mediates retinal ganglion cell loss during neuroinflammation

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) characterized by varying degrees of secondary neurodegeneration. Retinal ganglion cells (RGC) are lost in MS in association with optic neuritis but the mechanisms of neuronal injury remain unclear. Complement component C3 has been implicated in retinal and cerebral synaptic pathology that may precede neurodegeneration. Herein, we examined post-mortem MS retinas, and then used a mouse model, experimental autoimmune encephalomyelitis (EAE), to examine the role of C3 in the pathogenesis of RGC loss associated with optic neuritis. First, we show extensive C3 expression in astrocytes (C3⁺/GFAP⁺ cells) and significant RGC loss (RBPMS⁺ cells) in post-mortem retinas from people with MS compared to retinas from non-MS individuals. A patient with progressive MS with a remote history of optic neuritis showed marked reactive astrogliosis with C3 expression in the inner retina extending into deeper layers in the affected eye more than the unaffected eye. To study whether C3 mediates retinal degeneration, we utilized global C3^-/- EAE mice and found that they had less RGC loss and partially preserved neurites in the retina compared with C3^+/+ EAE mice. C3^-/- EAE mice had fewer axonal swellings in the optic nerve, reflecting reduced axonal injury, but had no changes in demyelination or T cell infiltration into the CNS. Using a C3-tdTomato reporter mouse line, we show definitive evidence of C3 expression in astrocytes in the retina and optic nerves of EAE mice. Conditional deletion of C3 in astrocytes showed RGC protection replicating the effects seen in the global knockouts. These data implicate astrocyte C3 expression as a critical mediator of retinal neuronal pathology in EAE and MS, and are consistent with recent studies showing C3 gene variants are associated with faster rates of retinal neurodegeneration in human disease.

Effects of the Menstrual Cycle on Neurological Disorders

PURPOSE OF REVIEW

The menstrual cycle involves recurrent fluctuations in hormone levels and temperature via neuroendocrine feedback loops. This paper reviews the impact of the menstrual cycle on several common neurological conditions, including migraine, seizures, multiple sclerosis, stroke, and Parkinson's disease.

RECENT FINDINGS

The ovarian steroid hormones, estrogen and progesterone, have protean effects on central nervous system functioning that can impact the likelihood, severity, and presentation of many neurological diseases. Hormonal therapies have been explored as a potential treatment for many neurological diseases with varying degrees of evidence and success. Neurological conditions also impact women's reproductive health, and the cessation of ovarian function with menopause may also alter the course of neurological diseases. Medication selection must consider hormonal effects on metabolism and the potential for adverse drug reactions related to menstruation, fertility, and pregnancy outcomes. Novel medications with selective affinity for hormonal receptors are desirable. Neurologists and gynecologists must collaborate to provide optimal care for women with neurological disorders.

Microglial Expression of Hdac1 and Hdac2 is Dispensable for Experimental Autoimmune Encephalomyelitis (EAE) Progression

Previously, we reported that microglial expression of histone deacetylases 1 and 2 (Hdac1 and Hdac2) is required for microglial maturation and modulates disease progression in a mouse model of Alzheimer’s disease. Here, we analyze the role of microglial expression of Hdac1 and Hdac2 in another disease paradigm, namely experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. The aim of this study was to ascertain whether microglial expression of these two epigenetic regulators modulates disease progression in the context of autoimmune disease. Hdac1 and Hdac2 were knocked out either individually or in combination using a microglia-specific, tamoxifen-inducible Cre-deleter line (Cx3cr1-CreERT2). The clinical course as well as histopathological changes during EAE were assessed in adult mice lacking microglial expression of these genes. Overall, no differences in disease onset, progression or severity could be detected in mice lacking microglial expression of either one or both of Hdac1 and Hdac2 genes. Similarly, the histopathology showed no differences in lymphocyte or macrophage infiltration or demyelination in either of the analyzed groups. As such, we conclude that unlike in neurodegenerative disease, microglial expression of Hdac1 and Hdac2 does not play a role in EAE.

Impact of natural menopause on multiple sclerosis: a multicentre study

OBJECTIVE

To study the effect of natural menopause on multiple sclerosis clinical course.

METHODS

This was an observational, retrospective, multicentre, cohort study. Menopause onset was defined by the final menstrual period (FMP) beyond which no menses occurred for 12 months. We included multiple sclerosis (MS) patients with FMP occurred after 2005 and a recorded follow-up of at least 2 years pre-FMP and post-FMP. We excluded patients with primary progressive course, iatrogenic menopause and with other confounders that could mask menopause onset. We compared relapse-rate and expanded disability status scale (EDSS) scores pre-FMP and post-FMP, searching for possible interactions with age, disease duration, cigarette smoking and nulliparity status.

RESULTS

148 patients were included (mean observation: 3.5 years pre-FMP and post-FMP). Most patients (92%) received disease-modifying therapies, mainly first-lines. After menopause the annualised relapse rate (ARR) significantly decreased (from 0.21±0.31 to 0.13± 0.24; p=0.005), while disability worsened (increase of mean 0.4 vs 0.2 points after menopause; p<0.001). Older age and long-lasting disease were associated with ARR reduction (p=0.013), but not with disability worsening. Cigarette smokers showed a trend to a higher disability accumulation after menopause (p=0.059).

CONCLUSION

Natural menopause seems to be a turning point to a more progressive phase of MS. Relapse rate is also reduced after menopause, but this effect could be driven most by ageing and shifting to progressive phase in patients with long-lasting disease. Cigarette smoking could speed up disability progression after menopause.

Molecular mechanisms involved in the protective actions of Selective Estrogen Receptor Modulators in brain cells

Synthetic selective modulators of the estrogen receptors (SERMs) have shown to protect neurons and glial cells against toxic insults. Among the most relevant beneficial effects attributed to these compounds are the regulation of inflammation, attenuation of astrogliosis and microglial activation, prevention of excitotoxicity and as a consequence the reduction of neuronal cell death. Under pathological conditions, the mechanism of action of the SERMs involves the activation of estrogen receptors (ERs) and G protein-coupled receptor for estrogens (GRP30). These receptors trigger neuroprotective responses such as increasing the expression of antioxidants and the activation of kinase-mediated survival signaling pathways. Despite the advances in the knowledge of the pathways activated by the SERMs, their mechanism of action is still not entirely clear, and there are several controversies. In this review, we focused on the molecular pathways activated by SERMs in brain cells, mainly astrocytes, as a response to treatment with raloxifene and tamoxifen.

Nav1.5 in astrocytes plays a sex-specific role in clinical outcomes in a mouse model of multiple sclerosis

Astrogliosis is a hallmark of neuroinflammatory disorders such as multiple sclerosis (MS). A detailed understanding of the underlying molecular mechanisms governing astrogliosis might facilitate the development of therapeutic targets. We investigated whether Nav1.5 expression in astrocytes plays a role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a murine model of MS. We created a conditional knockout of Nav1.5 in astrocytes and determined whether this affects the clinical course of EAE, focal macrophage and T cell infiltration, and diffuse activation of astrocytes. We show that deletion of Nav1.5 from astrocytes leads to significantly worsened clinical outcomes in EAE, with increased inflammatory infiltrate in both early and late stages of disease, unexpectedly, in a sex-specific manner. Removal of Nav1.5 in astrocytes leads to increased inflammation in female mice with EAE, including increased astroglial response and infiltration of T cells and phagocytic monocytes. These cellular changes are consistent with more severe EAE clinical scores. Additionally, we found evidence suggesting possible dysregulation of the immune response-particularly with regard to infiltrating macrophages and activated microglia-in female Nav1.5 KO mice compared with WT littermate controls. Together, our results show that deletion of Nav1.5 from astrocytes leads to significantly worsened clinical outcomes in EAE, with increased inflammatory infiltrate in both early and late stages of disease, in a sex-specific manner.

SERMs Promote Anti-Inflammatory Signaling and Phenotype of CD14+ Cells

Signaling via estrogen receptors (ER) is recognized as an essential part of the immune regulation, and ER-mediated signaling is involved in autoimmune reactions. Especially ERα activation in immune cells has been suggested to skew cytokine production toward Th2/M2-type mediators, which can have protective effect on inflammatory diseases and reduce Th1 and Th17 responses. These effects are caused by increased alternative activation of macrophages and changes in the activation of different T cell populations. In humans, hormonal status has been shown to have a major impact on several inflammatory diseases. Selective estrogen receptor modulators (SERMs) are ER ligands that regulate ER actions in a tissue-specific manner mostly lacking the adverse effects of steroid hormones. The impact of SERMs on the immune system is less studied, but it is suggested that certain SERMs may also produce immunoprotective effects. Here, we show that two novel SERMs and raloxifene affect immune cells by promoting M2 macrophage phenotype, alleviating NFκB activity, inhibiting T cell proliferation, and stimulating the production of anti-inflammatory compounds such as IL10 and IL1 receptor antagonist. Thus, these compounds have high potency as drug candidates against autoimmune diseases.

27-Hydroxycholesterol Is an Estrogen Receptor β-Selective Negative Allosteric Modifier of 17β-Estradiol Binding

Estrogens bind to two nuclear estrogen receptor (ER) subtypes, ERα and ERβ, which are expressed in differing amounts in various tissues. The endogenous estrogen, 17β-estradiol (E2), binds to both subtypes with nearly equal affinity and is the prototypical agonist. Selective estrogen receptor modulators (SERMs) may bind to both subtypes with equivalent affinities but have agonist activities in some tissues while having antagonist activities in others. In the present study, we demonstrate that the first reported endogenous SERM, 27-hydroxycholesterol (27-OHC), binds preferentially (>100-fold) to ERβ over ERα. Furthermore, 27-OHC is not able to fully compete with E2 binding, suggesting the two may bind at different sites. We provide an allosteric ternary complex model for the simultaneous binding of 27-OHC and E2 to ERβ, which accurately describes the binding data we have observed. We conclude that 27-OHC is a negative allosteric modifier of E2 binding, with an inhibitor constantof 50 nM and cooperativity factor (α) of 0.036. We also propose an in silico three-dimensional model of the simultaneous binding to guide future experiments. Further study of this unique binding model may allow for the discovery of novel ERβ-selective ligands and potentially explain the lack of effectiveness of ERβ-selective agonists in humans vs preclinical models.

Sex Steroids, Adult Neurogenesis, and Inflammation in CNS Homeostasis, Degeneration, and Repair

Sex steroidal hormones coordinate the development and maintenance of tissue architecture in many organs, including the central nervous systems (CNS). Within the CNS, sex steroids regulate the morphology, physiology, and behavior of a wide variety of neural cells including, but not limited to, neurons, glia, endothelial cells, and immune cells. Sex steroids spatially and temporally control distinct molecular networks, that, in turn modulate neural activity, synaptic plasticity, growth factor expression and function, nutrient exchange, cellular proliferation, and apoptosis. Over the last several decades, it has become increasingly evident that sex steroids, often in conjunction with neuroinflammation, have profound impact on the occurrence and severity of neuropsychiatric and neurodegenerative disorders. Here, I review the foundational discoveries that established the regulatory role of sex steroids in the CNS and highlight recent advances toward elucidating the complex interaction between sex steroids, neuroinflammation, and CNS regeneration through adult neurogenesis. The majority of recent work has focused on neuroinflammatory responses following acute physical damage, chronic degeneration, or pharmacological insult. Few studies directly assess the role of immune cells in regulating adult neurogenesis under healthy, homeostatic conditions. As such, I also introduce tractable, non-traditional models for examining the role of neuroimmune cells in natural neuronal turnover, seasonal plasticity of neural circuits, and extreme CNS regeneration.

Estrogen receptor β activation stimulates the development of experimental autoimmune thyroiditis through up-regulation of Th17-type responses

Estrogens play important roles in autoimmune thyroiditis, but it remains unknown which estrogen receptor (ER) subtype mediates the stimulatory effects. Herein we treated ovariectomized mice with ERα or ERβ selective agonist followed by thyroglobulin-immunization to induce experimental autoimmune thyroiditis (EAT), and observed the aggravation of EAT after diarylpropionitrile (DPN, ERβ selective agonist) administration. The mRNA levels of interleukin(IL)-17A, IL-21 and RORγt and percentages of T helper (Th) 17 cells were up-regulated in the splenocytes of DPN-treated mice. Activated ERβ was found directly binding to IL-17A and IL-21 gene promoters, and also indirectly promoting IL-21 and RORγt gene transcription through interaction with NF-κB. The expressions of co-stimulatory molecules were increased on antigen-presenting cells (APCs) after DPN administration. It suggests that ERβ is the predominant ER subtype responsible for EAT development, and its activation may enhance Th17-type responses through genomic pathways and alteration of APCs' activities.

Development of a high throughput drug screening assay to identify compounds that protect oligodendrocyte viability and differentiation under inflammatory conditions

Background

Newly proliferated oligodendrocyte precursor cells (OPCs) migrate and surround lesions of patients with multiple sclerosis (MS) and other demyelinating diseases, but fail to differentiate into oligodendrocytes (OLs) and remyelinate remaining viable axons. The abundance of secreted inflammatory factors within and surrounding these lesions likely plays a major inhibitory role, promoting cell death and preventing OL differentiation and axon remyelination. To identify clinical candidate compounds that may protect existing and differentiating OLs in patients, we have developed a high throughput screening (HTS) assay that utilizes purified rat OPCs.

Results

Using a fluorescent indicator of cell viability coupled with image quantification, we developed an assay to allow the identification of compounds that promote OL viability and differentiation in the presence of the synergistic inflammatory cytokines, tumor necrosis factor α and interferon-γ. We have utilized this assay to screen the NIH clinical collection library and identify compounds that protect OLs and promote OL differentiation in the presence of these inflammatory cytokines.

Conclusion

This primary OL-based cytokine protection assay is adaptable for HTS and may be easily modified for profiling of compounds in the presence of other potentially inhibitory molecules found in MS lesions. This assay should be of use to those interested in identifying drugs for the treatment of MS and other demyelinating diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-016-2219-8) contains supplementary material, which is available to authorized users.

A high throughput drug screening assay to identify compounds that promote oligodendrocyte differentiation using acutely dissociated and purified oligodendrocyte precursor cells

Background

Multiple sclerosis is caused by an autoimmune response resulting in demyelination and neural degeneration. The adult central nervous system has the capacity to remyelinate axons in part through the generation of new oligodendrocytes (OLs). To identify clinical candidate compounds that may promote remyelination, we have developed a high throughput screening (HTS) assay to identify compounds that promote the differentiation of oligodendrocyte precursor cells (OPCs) into OLs.

Results

Using acutely dissociated and purified rat OPCs coupled with immunofluorescent image quantification, we have developed an OL differentiation assay. We have validated this assay with a known promoter of differentiation, thyroid hormone, and subsequently used the assay to screen the NIH clinical collection library. We have identified twenty-seven hit compounds which were validated by dose response analysis and the generation of half maximal effective concentration (EC₅₀) values allowed for the ranking of efficacy. The assay identified novel promoters of OL differentiation which we attribute to (1) the incorporation of an OL toxicity pre-screen to allow lowering the concentrations of toxic compounds and (2) the utilization of freshly purified, non-passaged OPCs. These features set our assay apart from other OL differentiation assays used for drug discovery efforts.

Conclusions

This acute primary OL-based differentiation assay should be of use to those interested in screening large compound libraries for the identification of drugs for the treatment of MS and other demyelinating diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-016-2220-2) contains supplementary material, which is available to authorized users.

Neuropilin-1 modulates interferon-γ-stimulated signaling in brain microvascular endothelial cells

Inflammatory response of blood-brain barrier (BBB) endothelial cells plays an important role in pathogenesis of many central nervous system inflammatory diseases, including multiple sclerosis; however, the molecular mechanism mediating BBB endothelial cell inflammatory response remains unclear. In this study, we first observed that knockdown of neuropilin-1 (NRP1), a co-receptor of several structurally diverse ligands, suppressed interferon-γ (IFNγ)-induced C-X-C motif chemokine 10 expression and activation of STAT1 in brain microvascular endothelial cells in a Rac1-dependent manner. Moreover, endothelial-specific NRP1-knockout mice, VECadherin-Cre-ERT2/NRP1^flox/flox mice, showed attenuated disease progression during experimental autoimmune encephalomyelitis, a mouse neuroinflammatory disease model. Detailed analysis utilizing histological staining, quantitative PCR, flow cytometry and magnetic resonance imaging demonstrated that deletion of endothelial NRP1 suppressed neuron demyelination, altered lymphocyte infiltration, preserved BBB function and decreased activation of the STAT1-CXCL10 pathway. Furthermore, increased expression of NRP1 was observed in endothelial cells of acute multiple sclerosis lesions. Our data identify a new molecular mechanism of brain microvascular endothelial inflammatory response through NRP1-IFNγ crosstalk that could be a potential target for intervention of endothelial cell dysfunction in neuroinflammatory diseases.

Estrogens, Neuroinflammation, and Neurodegeneration

Inflammatory activation of microglia is a hallmark of several disorders of the central nervous system. In addition to protecting the brain against inflammatory insults, microglia are neuroprotective and play a significant role in maintaining neuronal connectivity, but the prolongation of an inflammatory status may limit the beneficial functions of these immune cells. The finding that estrogen receptors are present in monocyte-derived cells and that estrogens prevent and control the inflammatory response raise the question of the role that this sex steroid plays in the manifestation and progression of pathologies that have a clear sex difference in prevalence, such as multiple sclerosis, Parkinson's disease, and Alzheimer's disease. The present review aims to provide a critical review of the current literature on the actions of estrogen in microglia and on the involvement of estrogen receptors in the manifestation of selected neurological disorders. This current understanding highlights a research area that should be expanded to identify appropriate replacement therapies to slow the progression of such diseases.

Nudging oligodendrocyte intrinsic signaling to remyelinate and repair: Estrogen receptor ligand effects

Demyelination in multiple sclerosis (MS) leads to significant, progressive axonal and neuronal degeneration. Currently existing immunosuppressive and immunomodulatory therapies alleviate MS symptoms and slow, but fail to prevent or reverse, disease progression. Restoration of damaged myelin sheath by replenishment of mature oligodendrocytes (OLs) should not only restore saltatory axon conduction, but also provide a major boost to axon survival. Our previous work has shown that therapeutic treatment with the modestly selective generic estrogen receptor (ER) β agonist diarylpropionitrile (DPN) confers functional neuroprotection in a chronic experimental autoimmune encephalomyelitis (EAE) mouse model of MS by stimulating endogenous remyelination. Recently, we found that the more potent, selective ERβ agonist indazole-chloride (Ind-Cl) improves clinical disease and motor performance. Importantly, electrophysiological measures revealed improved corpus callosal conduction and reduced axon refractoriness. This Ind-Cl treatment-induced functional remyelination was attributable to increased OL progenitor cell (OPC) and mature OL numbers. At the intracellular signaling level, transition of early to late OPCs requires ERK1/2 signaling, and transition of immature to mature OLs requires mTOR signaling; thus, the PI3K/Akt/mTOR pathway plays a major role in the late stages of OL differentiation and myelination. Indeed, therapeutic treatment of EAE mice with various ERβ agonists results in increased brain-derived neurotrophic factor (BDNF) and phosphorylated (p) Akt and p-mTOR levels. It is notable that while DPN's neuroprotective effects occur in the presence of peripheral and central inflammation, Ind-Cl is directly neuroprotective, as demonstrated by remyelination effects in the cuprizone-induced demyelination model, as well as immunomodulatory. Elucidating the mechanisms by which ER agonists and other directly remyelinating agents modulate endogenous OPC and OL regulatory signaling is critical to the development of effective remyelinating drugs. The discovery of signaling targets to induce functional remyelination will valuably contribute to the treatment of demyelinating neurological diseases, including MS, stroke, and traumatic brain and spinal cord injury.

Symptoms of multiple sclerosis during use of combined hormonal contraception

OBJECTIVE

The incidence and disease course of multiple sclerosis (MS) is influenced by sex steroids, and several studies have shown less disease activity during high estrogen states. We have previously shown variation in symptom experience related to the estrogen/progestogen phase in women using combined hormonal contraceptives (CHC) in a small sample. The aim of this study was to confirm these results in a larger sample.

STUDY DESIGN

Self-assessment of symptoms of MS in relation to CHC cycle by 22 female MS patients. A symptom diary based on a validated instrument for cyclical symptoms was used. Mean symptom scores for high and low estrogen/progestogen phases were compared.

RESULTS

The women scored four out of ten symptoms significantly higher during the pill-free week than during the CHC phase (p<.05).

CONCLUSION

Women with MS report more pronounced symptoms during the pill-free, low-estrogen/progestogen phase of CHC use. Future studies should investigate, with a prospective, controlled design, the effects that continuous-use regimens of CHC have in women with MS.

Experimental and clinical evidence for the protective role of progesterone in motoneuron degeneration and neuroinflammation

Far beyond its role in reproduction, progesterone exerts neuro-protective, promyelinating, and anti-inflammatory effects in the nervous system. These effects are amplified under pathological conditions, implying that changes of the local environment sensitize nervous tissues to steroid therapy. The present survey covers our results of progesterone neuroprotection in a motoneuron neurodegeneration model and a neuroinflammation model. In the degenerating spinal cord of the Wobbler mouse, progesterone reverses the impaired expression of neurotrophins, increases enzymes of neurotransmission and metabolism, prevents oxidative damage of motoneurons and their vacuolar degeneration (paraptosis), and attenuates the development of mitochondrial abnormalities. After long-term treatment, progesterone also increases muscle strength and the survival of Wobbler mice. Subsequently, this review describes the effects of progesterone in mice with induced experimental autoimmune encephalomyelitis (EAE), a commonly used model of multiple sclerosis. In EAE mice, progesterone attenuates the clinical severity, decreases demyelination and neuronal dysfunction, increases axonal counts, reduces the formation of amyloid precursor protein profiles, and decreases the aberrant expression of growth-associated proteins. These actions of progesterone may be due to multiple mechanisms, considering that classic nuclear receptors, extranuclear receptors, and membrane receptors are all expressed in the spinal cord. Although many aspects of progesterone action in humans remain unsolved, data provided by experimental models makes getting to this objective closer than previously expected.

Pharmacotherapy with 17β-estradiol and progesterone prevents development of mouse experimental autoimmune encephalomyelitis

BACKGROUND

Pregnant women with multiple sclerosis (MS) show disease remission in the third trimester concomitant with high circulating levels of sex steroids. Rodent experimental autoimmune encephalomyelitis (EAE) is an accepted model for MS. Previous studies have shown that monotherapy with estrogens or progesterone exert beneficial effects on EAE. The aim of the present study was to determine if estrogen and progesterone cotherapy of C57BL/6 female mice provided substantial protection from EAE.

METHODS

A group of mice received single pellets of progesterone (100 mg) and 17 β-estradiol (2.5 mg) subcutaneously 1 week before EAE induction, whereas another group were untreated before EAE induction. On day 16 we compared the two EAE groups and control mice in terms of clinical scores, spinal cord demyelination, expression of myelin basic protein and proteolipid protein, macrophage cell infiltration, neuronal expression of brain-derived neurotrophic factor mRNA and protein, and the number of glial fribrillary acidic protein (GFAP)-immunopositive astrocytes.

RESULTS

Clinical signs of EAE were substantially attenuated by estrogen and progesterone treatment. Steroid cotherapy prevented spinal cord demyelination, infiltration of inflammatory cells and GFAP+ astrogliocytes to a great extent. In motoneurons, expression of BDNF mRNA and protein was highly stimulated, indicating concomitant beneficial effects of the steroid on neuronal and glial cells.

CONCLUSIONS

Cotherapy with estrogen and progesterone inhibits the development of major neurochemical abnormalities and clinical signs of EAE. We suggest that a combination of neuroprotective, promyelinating and immuno-suppressive mechanisms are involved in these beneficial effects.

G-protein-coupled receptor 30-mediated antiapoptotic effect of estrogen on spinal motor neurons following injury and its underlying mechanisms

Spinal cord injury (SCI) may result in severe dysfunction of motor neurons. G-protein-coupled receptor 30 (GPR30) expression in the motor neurons of the ventral horn of the spinal cord mediates neuroprotection through estrogen signaling. The present study explored the antiapoptotic effect of estrogen, mediated by GPR30 following SCI, and the mechanisms underlying this effect. Spinal motor neurons from rats were cultured in vitro in order to establish cell models of oxygen and glucose deprivation (OGD). The effects of estrogen, the estrogen agonist, G1, and the estrogen inhibitor, G15, on motor neurons were observed using MTT assays. The effects of E2, G1 and G15 on spinal motor neuron apoptosis following OGD, were detected using flow cytometry. The role of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) inhibitor, LY294002, was also determined using flow cytometry. Rat SCI models were established. E2, G1 and E2+LY294002 were administered in vivo. Motor function was scored at 3, 7, 14, 21 and 28 d following injury, using Basso-Beattie-Bresnahan (BBB) standards. Cell activity in the estrogen and G1 groups was higher than that in the solvent group, whereas cell activity in the E2+G15 group was lower than that in the E2 group (P<0.05). Following OGD, the proportion of apoptotic cells significantly increased (P<0.05). The proportion in the estrogen group was significantly lower than that in the solvent group, whereas the proportion of apoptotic cells in the E2+G15 and E2+LY294002 groups was higher than that in the E2 group (P<0.05). Treatment with E2 and G1 led to upregulation of P-Akt expression in normal cells and post-OGD cells. The BBB scores of rats in the E2 and G1 groups were higher than those in the placebo group (P<0.05). The BBB scores of the E2+LY294002 group were lower than those of the E2 group (P<0.05). Estrogen thus appears to exert a protective effect on spinal motor neurons following OGD, via GPR30. The PI3K/Akt pathway may be one of those involved in the estrogen-related antiapoptotic effects mediated by GPR30.

Multiple sclerosis at menopause: Potential neuroprotective effects of estrogen

Multiple sclerosis (MS) is an autoimmune demyelinating and neurodegenerative condition of the central nervous system that preferentially afflicts women more than men. Low estrogen states such as menopause and the postpartum period favor exacerbations of multiple sclerosis in women with the disease. Existing and emerging evidence suggests a role for estrogen in the alleviation of symptoms and reversal of pathology associated with MS. While clinical evidence is sparse regarding the benefit of estrogen therapy for women at risk for MS exacerbations, scientific data demonstrates that estrogen potentiates numerous neuroprotective effects on the central nervous system (CNS). Estrogens play a wide range of roles involved in MS disease pathophysiology, including increasing antiinflammatory cytokines, decreasing demyelination, and enhancing oxidative and energy producing processes in CNS cells.

Enhanced sphingosine-1-phosphate receptor 2 expression underlies female CNS autoimmunity susceptibility

Multiple sclerosis (MS) is an inflammatory disease of the CNS that is characterized by BBB dysfunction and has a much higher incidence in females. Compared with other strains of mice, EAE in the SJL mouse strain models multiple features of MS, including an enhanced sensitivity of female mice to disease; however, the molecular mechanisms that underlie the sex- and strain-dependent differences in disease susceptibility have not been described. We identified sphingosine-1-phosphate receptor 2 (S1PR2) as a sex- and strain-specific, disease-modifying molecule that regulates BBB permeability by destabilizing adherens junctions. S1PR2 expression was increased in disease-susceptible regions of the CNS of both female SJL EAE mice and female patients with MS compared with their male counterparts. Pharmacological blockade or lack of S1PR2 signaling decreased EAE disease severity as the result of enhanced endothelial barrier function. Enhanced S1PR2 signaling in an in vitro BBB model altered adherens junction formation via activation of Rho/ROCK, CDC42, and caveolin endocytosis-dependent pathways, resulting in loss of apicobasal polarity and relocation of abluminal CXCL12 to vessel lumina. Furthermore, S1PR2-dependent BBB disruption and CXCL12 relocation were observed in vivo. These results identify a link between S1PR2 signaling and BBB polarity and implicate S1PR2 in sex-specific patterns of disease during CNS autoimmunity.

Raloxifene suppresses experimental autoimmune encephalomyelitis and NF-κB-dependent CCL20 expression in reactive astrocytes

Recent clinical data have led to the consideration of sexual steroids as new potential therapeutic tools for multiple sclerosis. Selective estrogen receptor modulators can exhibit neuroprotective effects like estrogen, with fewer systemic estrogen side effects than estrogen, offering a more promising therapeutic modality for multiple sclerosis. The important role of astrocytes in a proinflammatory effect mediated by CCL20 signaling on inflammatory cells has been documented. Their potential contribution to selective estrogen receptor modulator-mediated protection is still unknown. Using a mouse model of chronic neuroinflammation, we report that raloxifene, a selective estrogen receptor modulator, alleviated experimental autoimmune encephalomyelitis–an animal model of multiple sclerosis–and decreased astrocytic production of CCL20. Enzyme-linked immunosorbent assay, immunohistochemistry imaging and transwell migration assays revealed that reactive astrocytes express CCL20, which promotes Th17 cell migration. In cultured rodent astrocytes, raloxifene inhibited IL-1β-induced CCL20 expression and chemotaxis ability for Th17 migration, whereas the estrogen receptor antagonist ICI 182,780 blocked this effect. Western blotting further indicated that raloxifene suppresses IL-1β-induced NF-κB activation (phosphorylation of p65) and translocation but does not affect phosphorylation of IκB. In conclusion, these data demonstrate that raloxifene provides robust neuroprotection against experimental autoimmune encephalomyelitis, partially via an inhibitory action on CCL20 expression and NF-κB pathways in reactive astrocytes. Our results contribute to a better understanding of the critical roles of raloxifene in treating experimental autoimmune encephalomyelitis and uncover reactive astrocytes as a new target for the inhibitory action of estrogen receptors on chemokine CCL20 expression.

Progesterone protective effects in neurodegeneration and neuroinflammation

Progesterone is a neuroprotective, promyelinating and anti-inflammatory factor for the nervous system. Here, we review the effects of progesterone in models of motoneurone degeneration and neuroinflammation. In neurodegeneration of the Wobbler mouse, a subset of spinal cord motoneurones showed increased activity of nitric oxide synthase (NOS), increased intramitochondrial NOS, decreased activity of respiratory chain complexes, and decreased activity and protein expression of Mn-superoxide dismutase type 2 (MnSOD2). Clinically, Wobblers suffered several degrees of motor impairment. Progesterone treatment restored the expression of neuronal markers, decreased the activity of NOS and enhanced complex I respiratory activity and MnSOD2. Long-term treatment with progesterone increased muscle strength, biceps weight and survival. Collectively, these data suggest that progesterone prevented neurodegeneration. To study the effects of progesterone in neuroinflammation, we employed mice with experimental autoimmune encephalomyelitis (EAE). EAE mice spinal cord showed increased mRNA levels of the inflammatory mediators tumour necrosis factor (TNF)α and its receptor TNFR1, the microglial marker CD11b, inducible NOS and the toll-like receptor 4. Progesterone pretreatment of EAE mice blocked the proinflammatory mediators, decreased Iba1+ microglial cells and attenuated clinical signs of EAE. Therefore, reactive glial cells became targets of progesterone anti-inflammatory effects. These results represent a starting point for testing the usefulness of neuroactive steroids in neurological disorders.

Estrogen mediates neuroprotection and anti-inflammatory effects during EAE through ERα signaling on astrocytes but not through ERβ signaling on astrocytes or neurons

Estrogens can signal through either estrogen receptor α (ERα) or β (ERβ) to ameliorate experimental autoimmune encephalomyelitis (EAE), the most widely used mouse model of multiple sclerosis (MS). Cellular targets of estrogen-mediated neuroprotection are still being elucidated. Previously, we demonstrated that ERα on astrocytes, but not neurons, was critical for ERα ligand-mediated neuroprotection in EAE, including decreased T-cell and macrophage inflammation and decreased axonal loss. Here, we determined whether ERβ on astrocytes or neurons could mediate neuroprotection in EAE, by selectively removing ERβ from either of these cell types using Cre-loxP gene deletion. Our results demonstrated that, even though ERβ ligand treatment was neuroprotective in EAE, this neuroprotection was not mediated through ERβ on either astrocytes or neurons and did not involve a reduction in levels of CNS inflammation. Given the differential neuroprotective and anti-inflammatory effects mediated via ERα versus ERβ on astrocytes, we looked for molecules within astrocytes that were affected by signaling through ERα, but not ERβ. We found that ERα ligand treatment, but not ERβ ligand treatment, decreased expression of the chemokines CCL2 and CCL7 by astrocytes in EAE. Together, our data show that neuroprotection in EAE mediated via ERβ signaling does not require ERβ on either astrocytes or neurons, whereas neuroprotection in EAE mediated via ERα signaling requires ERα on astrocytes and reduces astrocyte expression of proinflammatory chemokines. These findings reveal important cellular differences in the neuroprotective mechanisms of estrogen signaling through ERα and ERβ in EAE.

Selective estrogen receptor modulators for BPH: new factors on the ground

As the current management of BPH/lower urinary tract symptoms by traditionally involved pharmacological agents such as 5alpha-reductase inhibitors and α1-adrenoceptor antagonists is suboptimal, there is definite need of new therapeutic strategies. There is ample evidence in literature that suggests the role of estrogens in BPH development and management through the different tissue and cell-specific receptors. This article reviews the beneficial actions of selective estrogen receptor modulator (SERM) and ERβ-selective ligands, which have been demonstrated through in vitro studies using human prostate cell lines and in vivo animal studies. SERMs have anti-proliferative, anti-inflammatory and pro-apoptotic mechanisms in BPH, and also act by inhibiting various growth factors, and thus represent a unique and novel approach in BPH management directed at estrogen receptors or estrogen metabolism.

The influence of pregnancy on systemic immunity

Adaptations in maternal systemic immunity are presumed to be responsible for observed alterations in disease susceptibility and severity as pregnancy progresses. Epidemiological evidence as well as animal studies have shown that influenza infections are more severe during the second and third trimesters of pregnancy, resulting in greater morbidity and mortality, although the reason for this is still unclear. Our laboratory has taken advantage of 20 years of experience studying the murine immune response to respiratory viruses to address questions of altered immunity during pregnancy. With clinical studies and unique animal model systems, we are working to define the mechanisms responsible for altered immune responses to influenza infection during pregnancy and what roles hormones such as estrogen or progesterone play in these alterations.

Progesterone down-regulates spinal cord inflammatory mediators and increases myelination in experimental autoimmune encephalomyelitis

In mice with experimental autoimmune encephalomyelitis (EAE) pretreatment with progesterone improves clinical signs and decreases the loss of myelin basic protein (MBP) and proteolipid protein (PLP) measured by immunohistochemistry and in situ hybridization. Presently, we analyzed if progesterone effects in the spinal cord of EAE mice involved the decreased transcription of local inflammatory mediators and the increased transcription of myelin proteins and myelin transcription factors. C57Bl/6 female mice were divided into controls, EAE and EAE receiving progesterone (100mg implant) 7 days before EAE induction. Tissues were collected on day 17 post-immunization. Real time PCR technology demonstrated that progesterone blocked the EAE-induced increase of the proinflammatory mediators tumor necrosis factor alpha (TNFα) and its receptor TNFR1, the microglial marker CD11b and toll-like receptor 4 (TLR4) mRNAs, and increased mRNA expression of PLP and MBP, the myelin transcription factors NKx2.2 and Olig1 and enhanced CC1+oligodendrocyte density respect of untreated EAE mice. Immunocytochemistry demonstrated decreased Iba1+microglial cells. Confocal microscopy demonstrated that TNFα colocalized with glial-fibrillary acidic protein+astrocytes and OX-42+microglial cells. Therefore, progesterone treatment improved the clinical signs of EAE, decreased inflammatory glial reactivity and increased myelination. Data suggest that progesterone neuroprotection involves the modulation of transcriptional events in the spinal cord of EAE mice.

Estrogen mediates innate and adaptive immune alterations to influenza infection in pregnant mice

Pregnancy is a leading risk factor for severe complications during an influenza virus infection. Women infected during their second and third trimesters are at increased risk for severe cardiopulmonary complications, premature delivery, and death. Here, we establish a murine model of aerosolized influenza infection during pregnancy. We find significantly altered innate antiviral responses in pregnant mice, including decreased levels of IFN-β, IL-1α, and IFN-γ at early time points of infection. We also find reduced cytotoxic T cell activity and delayed viral clearance. We further demonstrate that pregnancy levels of the estrogen 17-β-estradiol are able to induce key anti-inflammatory phenotypes in immune responses to the virus independently of other hormones or pregnancy-related stressors. We conclude that elevated estrogen levels result in an attenuated anti-viral immune response, and that pregnancy-associated morbidities occur in the context of this anti-inflammatory phenotype.

Sex-related factors in multiple sclerosis susceptibility and progression

The pathogenesis of multiple sclerosis (MS) involves complex interactions between genetic susceptibility and environmental triggers. Clinical observations suggest that the study of sex differences might provide important insight into mechanisms of pathogenesis and progression of the disease in patients. MS occurs more frequently in women than in men, indicating that sex-related factors have an effect on an individual's susceptibility to developing the condition. These factors include hormonal, genetic and environmental influences, as well as gene-environment interactions and epigenetic mechanisms. Interestingly, women do not have a poorer prognosis than men with MS despite a higher incidence of the disease and more-robust immune responses, which suggests a mechanism of resilience. Furthermore, the state of pregnancy has a substantial effect on disease activity, characterized by a reduction in relapse rates during the third trimester but an increased relapse rate in the postpartum period. However, pregnancy has little effect on long-term disability in women with MS. The unravelling of the mechanisms underlying these clinical observations in the laboratory and application of the results to the clinical setting is a unique and potentially fruitful strategy to develop novel therapeutic approaches for MS.

Primary oligodendrocyte death does not elicit anti-CNS immunity

Anti-myelin immunity is commonly thought to drive multiple sclerosis, yet the initial trigger of this autoreactivity remains elusive. One of the proposed factors for initiating this disease is the primary death of oligodendrocytes. To specifically test such oligodendrocyte death as a trigger for anti-CNS immunity, we inducibly killed oligodendrocytes in an in vivo mouse model. Strong microglia-macrophage activation followed oligodendrocyte death, and myelin components in draining lymph nodes made CNS antigens available to lymphocytes. However, even conditions favoring autoimmunity-bystander activation, removal of regulatory T cells, presence of myelin-reactive T cells and application of demyelinating antibodies-did not result in the development of CNS inflammation after oligodendrocyte death. In addition, this lack of reactivity was not mediated by enhanced myelin-specific tolerance. Thus, in contrast with previously reported impairments of oligodendrocyte physiology, diffuse oligodendrocyte death alone or in conjunction with immune activation does not trigger anti-CNS immunity.

Neuroprotective effects of estrogens and androgens in CNS inflammation and neurodegeneration

Multiple sclerosis (MS) is a disease characterized by inflammation and demyelination. Currently, the cause of MS is unknown. Experimental autoimmune encephalomyelitis (EAE) is the most common mouse model of MS. Treatments with the sex hormones, estrogens and androgens, are capable of offering disease protection during EAE and are currently being used in clinical trials of MS. Beyond endogenous estrogens and androgens, treatments with selective estrogen receptor modulators (SERMs) for estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) are also capable of providing disease protection. This protection includes, but is not limited to, prevention of clinical disease, reduction of CNS inflammation, protection against demyelination, and protection against axonal loss. In EAE, current efforts are focused on using conditional cell specific knockouts of sex hormone receptors to identify the in vivo targets of these estrogens and androgens as well as downstream molecules responsible for disease protection.

17β-Estradiol and interferon tau interact in the regulation of the immune response in a model of experimental autoimmune orchitis

Immunoregulatory activity of type I interferons (IFNs) and estrogen is convergent in some cases of autoimmune disorders. The aim of our study was to determine whether a potent interaction of IFN and estradiol (E2) has an influence on immune response and estrogen receptor alpha (ER-?) expression in antigen-presenting cells in a model of experimental autoimmune orchitis (EAO). C3H/He/W male mice were immunized with testicular germ cells (TGCs) and orally treated with interferon tau (IFN-?), E2, or both simultaneously. The delayed-type hypersensitivity reaction was intensified after the administration of either IFN-? or E2, but their co-administration had no effect. IFN-? treatment increased immunoglobulin G2a (IgG2a) and decreased IgG1 levels of TGC-specific antibodies, whereas E2 abolished the effects of the used cytokine. The total splenic cellularity and the number of spleen CD11c+MHC II+ and F4/80+MHC II? cells were increased after IFN-? treatment, whereas E2 antagonized this effect. After IFN-? administration the level of ER-? was significantly higher in F4/80+MHC II? cells, whereas E2 had no effect. However, the administration of E2 significantly reduced the ER-? level in F4/80+MHC II+ and CD11c+MHC II+ cells in comparison with the IFN-??treated groups. In the EAO model, the type I IFN and E2 cooperated at the general and cellular levels of immune response, but E2 treatment usually abolished the effects exerted by the cytokine.

Sex differences in autoimmune diseases

Women are more susceptible to a variety of autoimmune diseases including systemic lupus erythematosus (SLE), multiple sclerosis (MS), primary biliary cirrhosis, rheumatoid arthritis and Hashimoto's thyroiditis. This increased susceptibility in females compared to males is also present in animal models of autoimmune diseases such as spontaneous SLE in (NZBxNZW)F1 and NZM.2328 mice, experimental autoimmune encephalomyelitis (EAE) in SJL mice, thyroiditis, Sjogren's syndrome in MRL/Mp-lpr/lpr mice and diabetes in non-obese diabetic mice. Indeed, being female confers a greater risk of developing these diseases than any single genetic or environmental risk factor discovered to date. Understanding how the state of being female so profoundly affects autoimmune disease susceptibility would accomplish two major goals. First, it would lead to an insight into the major pathways of disease pathogenesis and, secondly, it would likely lead to novel treatments which would disrupt such pathways.

Gender differences in 1,25 dihydroxyvitamin D3 immunomodulatory effects in multiple sclerosis patients and healthy subjects

Vitamin D(3) is best known as a calcium homeostasis modulator; however, it also has immune-modulating potential. In this study, we demonstrated that immunomodulatory effects of vitamin D(3) are significantly stronger in females than in males in multiple sclerosis patients, as well as in healthy subjects. Inhibition of self-reactive T cell proliferation and reduction in IFN-γ- and IL-17-secreting cell numbers were considerably greater in females. Furthermore, the increase in IL-10-secreting and CD4(+)CD25(+)FoxP3(+) regulatory T cell numbers were also greater in females. In parallel with these findings, female subjects had fewer CYP24A1 transcripts encoding the 1,25-dihydroxyvitamin D(3)-inactivating enzyme, as well as greater binding and internalization of vitamin D(3)-binding protein, a transporter for vitamin D(3) and its metabolites. These gender-based disparities lead to the accumulation of vitamin D(3) and its metabolites in target cells from female subjects and result in a more potent anti-inflammatory effect. Interestingly, 17-β estradiol reproduced these effects on self-reactive T cells and macrophages from male subjects, suggesting a functional synergy between 1,25-dihydroxyvitamin D(3) and 17-β estradiol, mediated through estrogen receptor α. Collectively, these results demonstrate estrogen-promoted differences in vitamin D(3) metabolism, suggesting a greater protective effect of vitamin D(3)-based therapeutic strategies in women.

17beta-estradiol protects male mice from cuprizone-induced demyelination and oligodendrocyte loss

In addition to regulating reproductive functions in the brain and periphery, estrogen has tropic and neuroprotective functions in the central nervous system (CNS). Estrogen administration has been demonstrated to provide protection in several animal models of CNS disorders, including stroke, brain injury, epilepsy, Parkinson's disease, Alzheimer's disease, age-related cognitive decline and multiple sclerosis. Here, we use a model of toxin-induced oligodendrocyte death which results in demyelination, reactive gliosis, recruitment of oligodendrocyte precursor cells and subsequent remyelination to study the potential benefit of 17beta-estradiol (E2) administration in male mice. The results indicate that E2 partially ameliorates loss of oligodendrocytes and demyelination in the corpus callosum. This protection is accompanied by a delay in microglia accumulation as well as reduced mRNA expression of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFalpha), and insulin-like growth factor-1 (IGF-1). E2 did not significantly alter the accumulation of astrocytes or oligodendrocyte precursor cells, or remyelination. These data obtained from a toxin-induced, T cell-independent model using male mice provide an expanded view of the beneficial effects of estrogen on oligodendrocyte and myelin preservation.

The role of estrogen receptor beta (ERbeta) in malignant diseases--a new potential target for antiproliferative drugs in prevention and treatment of cancer

The discovery of ERbeta in the middle of the 1990s represents a paradigm shift in our understanding of estrogen signaling. It has turned out that estrogen action is not mediated by one receptor, ERalpha, but by two balancing factors, ERalpha and ERbeta, which are often antagonistic to one another. Excitingly, ERbeta has been shown to be widespread in the body and to be involved in a multitude of physiological and pathophysiological events. This has led to a strong interest of the pharmaceutical industry to target ERbeta by drugs against various diseases. In this review, focus is on the role of ERbeta in malignant diseases where the anti proliferative activity of ERbeta gives hope of new therapeutic approaches.