Neuroimmunoprotective effects of estrogen and derivatives in experimental autoimmune encephalomyelitis: Therapeutic implications for multiple sclerosis

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.

Biological Sex As a Critical Variable in CD4+ Effector T Cell Function in Preclinical Models of Multiple Sclerosis

Significance: T cells play a pivotal role in maintaining adaptive immune responses against pathogens. However, misdirected T cell responses against self-tissues may lead to autoimmune disease. Biological sex has profound effects on T cell function and is an important determinant of disease incidence and severity in autoimmune diseases such as multiple sclerosis (MS). Recent Advances: Many autoimmune diseases skew toward higher female incidence, including MS; however, it is has become increasingly more accepted that men living with MS are more prone to developing a progressive disease course and to having worsened disease outcomes. Critical Issues: In this review, we discuss what is known about the role of biological sex on T cell development and differentiation, examining evidence that male sex can augment T helper 17 (Th17) responses. Next, we outline what is known about sex differences in animal models of MS, and about the distinct roles played by sex hormones versus sex chromosomes in pathogenesis in these models. Finally, we discuss recent advances that examine the molecular basis for worsened disease outcomes in males, with a particular focus on the role played by Th17 cells in these models. Future Directions: Better understanding the role of biological sex in T cell function may pave the way to effective personalized treatment strategies in MS and other autoimmune diseases. Antioxid. Redox Signal. 37, 135-149.

Nestorone® , a 19nor-progesterone derivative boosts remyelination in an animal model of demyelination

INTRODUCTION

We previously showed that Nestorone^® (NES), a synthetic progestin structurally related to progesterone, stimulated remyelination of the corpus callosum in a Cuprizone (CUP) mouse model of demyelination in intact females by promoting replenishment with mature oligodendrocytes (OL) (Glia. 2015;63:104-117). Here, we further investigated the underlying mechanisms of this promyelinating effect.

METHODS

We explored whether NES, applied subcutaneously through Alzet mini-osmotic pumps, regulates specific transcription factors involved in oligodendrocyte progenitor cell (OPC) proliferation and their differentiation into mature OL, using RT-qPCR and Western Blot analysis.

RESULTS

Our present data show that in comparison to controls, a one-week treatment with NES, through Alzet mini-osmotic pumps, enhanced the production of three relevant transcription factor mRNAs encoding Olig2, Myt1, and Sox17. After 3 weeks, NES treatment reversed the effect of CUP on the levels of corresponding Olig2, Myt1, and Sox17 proteins. Moreover, in mice receiving NES + Estradiol (E2) co-treatment, levels of Olig2, Myt1, and Sox17 proteins did not change as compared to NES alone.

CONCLUSION

NES alone or with E2 increased the levels of transcription factors, essential for myelin synthesis.

Towards a comprehensive etiopathogenetic and pathophysiological theory of multiple sclerosis

Background: Multiple sclerosis (MS) is a neurodegenerative disease caused by dysfunction of the immune system that affects the central nervous system (CNS). It is characterized by demyelination, chronic inflammation, neuronal and oligodendrocyte loss and reactive astrogliosis. It can result in physical disability and acute neurological and cognitive problems. Despite the gains in knowledge of immunology, cell biology, and genetics in the last five decades, the ultimate etiology or specific elements that trigger MS remain unknown. The objective of this review is to propose a theoretical basis for MS etiopathogenesis.Methods: Search was done by accessing PubMed/Medline, EBSCO, and PsycINFO databases. The search string used was "(multiple sclerosis* OR EAE) AND (pathophysiology* OR etiopathogenesis)". The electronic databases were searched for titles or abstracts containing these terms in all published articles between January 1, 1960, and June 30, 2019. The search was filtered down to 362 articles which were included in this review.Results: A framework to better understand the etiopathogenesis and pathophysiology of MS can be derived from four essential factors; mitochondria dysfunction (MtD) & oxidative stress (OS), vitamin D (VD), sex hormones and thyroid hormones. These factors play a direct role in MS etiopathogenesis and have a modulatory effect on many other factors involved in the disease.Conclusions: For better MS prevention and treatment outcomes, efforts should be geared towards treating thyroid problems, sex hormone alterations, VD deficiency, sleep problems and melatonin alterations. MS patients should be encouraged to engage in activities that boost total antioxidant capacity (TAC) including diet and regular exercise and discouraged from activities that promote OS including smoking and alcohol consumption.

Muscle metabolism and atrophy: let's talk about sex

Skeletal muscle health is a strong predictor of overall health and longevity. Pathologies affecting skeletal muscle such as cancer cachexia, intensive care unit treatment, muscular dystrophies, and others are associated with decreased quality of life and increased mortality. Recent research has begun to determine that these muscular pathologies appear to present and develop differently between males and females. However, to our knowledge, there has yet to be a comprehensive review on musculoskeletal differences between males and females and how these differences may contribute to sex differences in muscle pathologies. Herein, we present a review of the current literature on muscle phenotype and physiology between males and females and how these differences may contribute to differential responses to atrophic stimuli. In general, females appear to be more susceptible to disuse induced muscle wasting, yet protected from inflammation induced (such as cancer cachexia) muscle wasting compared to males. These differences may be due in part to differences in muscle protein turnover, satellite cell content and proliferation, hormonal interactions, and mitochondrial differences between males and females. However, more works specifically examining muscle pathologies in females are necessary to more fully understand the inherent sex-based differences in muscle pathologies between the sexes and how they may correspond to different clinical treatments.

Insights into Initial Demyelinating Episodes of Central Nervous System during Puerperium

Background:

Inflammatory demyelinating disease of central nervous system (CNS) is an inflammatory disease characterized by a high childbearing female predominance. Labor-related alterations for postpartum demyelinating attacks are not entirely clear. This study aimed to summarize clinical features of female patients of reproductive age with initial CNS inflammatory demyelinating attacks during puerperium.

Methods:

Fourteen female patients with initial demyelinating events during puerperium between January 2013 and December 2016 were retrospectively studied. Records of clinical features, neuroimaging, serum antibodies, cerebrospinal fluid (CSF) findings, annualized relapse rate (ARR), and treatment were analyzed.

Results:

Among 14 patients, 5 patients were diagnosed with multiple sclerosis (MS), four as neuromyelitis optica (NMO), two as longitudinal extensive transverse myelitis, two as clinical isolated syndrome (CIS), and one as acute brainstem syndrome. All the 14 puerperal female patients presented with more than one manifestation of hemiplegia, paraplegia, uroschesis, visual loss or dysarthria, and with mild to moderate abnormalities of CSF. Attacks occurred during the first trimester postpartum and cesarean section was the main delivery way (n = 10). Median Expanded Disability Status Scale (EDSS) scores were 5.0 (range: 2.0–9.0) at the onset and 2.5 (range: 0–7.0) at the end of follow-ups. Patients with MS and CIS had a significantly lower EDSS scores than patients with NMO spectrum disorders (P < 0.05). Median ARR was 0.46 (range: 0–1.16); all patients had a low ARR (0.49 ± 0.34, 95% confidence interval: 0.29–0.69) with standardized treatments.

Conclusion:

Labor-related alterations in the mother's immune system might result in newly-onset demyelinating diseases of central nervous system.

GPER modulators: Opportunity Nox on the heels of a class Akt

The (patho)physiology of estrogen and its receptors is complex. It is therefore not surprising that therapeutic approaches targeting this hormone include stimulation of its activity through supplementation with either the hormone itself or natural or synthetic agonists, inhibition of its activity through the use of antagonists or inhibitors of its synthesis, and tissue-selective modulation of its activity with biased ligands. The physiology of this hormone is further complicated by the existence of at least three receptors, the classical nuclear estrogen receptors α and β (ERα and ERβ), and the 7-transmembrane G protein-coupled estrogen receptor (GPER/GPR30), with overlapping but distinct pharmacologic profiles, particularly of anti-estrogenic ligands. GPER-selective ligands, as well as GPER knockout mice, have greatly aided our understanding of the physiological roles of GPER. Such ligands have revealed that GPER activation mediates many of the rapid cellular signaling events (including Ca2+ mobilization, ERK and PI3K/Akt activation) associated with estrogen activity, as opposed to the nuclear ERs that are traditionally described to function as ligand-induced transcriptional factors. Many of the salutary effects of estrogen throughout the body are reproduced by the GPER-selective agonist G-1, which, owing to its minimal effects on reproductive tissues, can be considered a non-feminizing estrogenic compound, and thus of potential therapeutic use in both women and men. On the contrary, until recently GPER-selective antagonists had predominantly found preclinical application in cancer models where estrogen stimulates cell growth and survival. This viewpoint changed recently with the discovery that GPER is associated with aging, particularly that of the cardiovascular system, where the GPER antagonist G36 reduced hypertension and GPER deficiency prevented cardiac fibrosis and vascular dysfunction with age, through the downregulation of Nox1 and as a consequence superoxide production. Thus, similar to the classical ERs, both agonists and antagonists of GPER may be of therapeutic benefit depending on the disease or condition to be treated.

Effects of Chronic Vitamin D₃ Hormone Administration on Anxiety-Like Behavior in Adult Female Rats after Long-Term Ovariectomy

The present preclinical study was created to determine the therapeutic effects of vitamin D hormone treatment as an adjunctive therapy alone or in a combination with low dose of 17β-estradiol (17β-E₂) on anxiety-like behavior in female rats with long-term absence of estrogen. Accordingly, the aim of the current study was to examine the effects of chronic cholecalciferol administration (1.0, 2.5 or 5.0 mg/kg subcutaneously, SC, once daily, for 14 days) on the anxiety-like state after long-term ovariectomy in female rats. Twelve weeks postovariectomy, cholecalciferol was administered to ovariectomized (OVX) rats and OVX rats treated with 17β-E₂ (0.5 µg/rat SC, once daily, for 14 days). Anxiety-like behavior was assessed in the elevated plus maze (EPM) and the light/dark test (LDT), and locomotor and grooming activities were tested in the open field test (OFT). Cholecalciferol at two doses of 1.0 and 2.5 mg/kg alone or in combination with 17β-E₂ produced anxiolytic-like effects in OVX rats as evidenced in the EPM and the LDT, as well as increased grooming activity in the OFT. Our results indicate that cholecalciferol, at two doses of 1.0 and 2.5 mg/kg, has a profound anxiolytic-like effects in the experimental rat model of long-term estrogen deficiency.

Multiple Sclerosis and Obesity: Possible Roles of Adipokines

Multiple Sclerosis (MS) is an autoimmune disorder of the Central Nervous System that has been associated with several environmental factors, such as diet and obesity. The possible link between MS and obesity has become more interesting in recent years since the discovery of the remarkable properties of adipose tissue. Once MS is initiated, obesity can contribute to increased disease severity by negatively influencing disease progress and treatment response, but, also, obesity in early life is highly relevant as a susceptibility factor and causally related risk for late MS development. The aim of this review was to discuss recent evidence about the link between obesity, as a chronic inflammatory state, and the pathogenesis of MS as a chronic autoimmune and inflammatory disease. First, we describe the main cells involved in MS pathogenesis, both from neural tissue and from the immune system, and including a new participant, the adipocyte, focusing on their roles in MS. Second, we concentrate on the role of several adipokines that are able to participate in the mediation of the immune response in MS and on the possible cross talk between the latter. Finally, we explore recent therapy that involves the transplantation of adipocyte precursor cells for the treatment of MS.

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.

Adoptively transferred Tregs accumulate in a site-specific manner and ameliorate signs of less advanced collagen-induced arthritis progress in rats

AIM

The aim of the study was to assess the therapeutic effect and migration of adoptively transferred Tregs in the course of collagen-induced arthritis (CIA) in rats.

METHODS

Sorted CD4(+)CD25(+) cells were cultured in the presence of 17-β-estradiol, stained with CellTracker and then administered into the articular capsule of ankle joint of animals in different stages of CIA progression.

RESULTS

Tregs diminished CIA signs only in animals with less advanced disease progress. Moreover, migration of transferred cells into the LN in the near proximity of the injection site and with distal location was almost completely stopped in animals with fully developed CIA.

CONCLUSION

Disease progression-related differences in migratory potential of in vitro induced Tregs may be responsible for the failure of cellular therapy during the advanced stages of CIA.

Analytical challenges for measuring steroid responses to stress, neurodegeneration and injury in the central nervous system

Levels of steroids in the adult central nervous system (CNS) show marked changes in response to stress, degenerative disorders and injury. However, their analysis in complex matrices such as fatty brain and spinal cord tissues, and even in plasma, requires accurate and precise analytical methods. Radioimmunoassays (RIA) and enzyme-linked immunosorbent assays, even with prepurification steps, do not provide sufficient specificity, and they are at the origin of many inconsistent results in the literature. The analysis of steroids by mass spectrometric methods has become the gold standard for accurate and sensitive steroid analysis. However, these technologies involve multiple purification steps prone to errors, and they only provide accurate reference values when combined with careful sample workup. In addition, the interpretation of changes in CNS steroid levels is not an easy task because of their multiple sources: the endocrine glands and the local synthesis by neural cells. In the CNS, decreased steroid levels may reflect alterations of their biosynthesis, as observed in the case of chronic stress, post-traumatic stress disorders or depressive episodes. In such cases, return to normalization by administering exogenous hormones or by stimulating their endogenous production may have beneficial effects. On the other hand, increases in CNS steroids in response to acute stress, degenerative processes or injury may be part of endogenous protective or rescue programs, contributing to the resistance of neural cells to stress and insults. The aim of this review is to encourage a more critical reading of the literature reporting steroid measures, and to draw attention to the absolute need for well-validated methods. We discuss reported findings concerning changing steroid levels in the nervous system by insisting on methodological issues. An important message is that even recent mass spectrometric methods have their limits, and they only become reliable tools if combined with careful sample preparation.

What have we learned about GPER function in physiology and disease from knockout mice?

Estrogens, predominantly 17β-estradiol, exert diverse effects throughout the body in both normal and pathophysiology, during development and in reproductive, metabolic, endocrine, cardiovascular, nervous, musculoskeletal and immune systems. Estrogen and its receptors also play important roles in carcinogenesis and therapy, particularly for breast cancer. In addition to the classical nuclear estrogen receptors (ERα and ERβ) that traditionally mediate predominantly genomic signaling, the G protein-coupled estrogen receptor GPER has become recognized as a critical mediator of rapid signaling in response to estrogen. Mouse models, and in particular knockout (KO) mice, represent an important approach to understand the functions of receptors in normal physiology and disease. Whereas ERα KO mice display multiple significant defects in reproduction and mammary gland development, ERβ KO phenotypes are more limited, and GPER KO exhibit no reproductive deficits. However, the study of GPER KO mice over the last six years has revealed that GPER deficiency results in multiple physiological alterations including obesity, cardiovascular dysfunction, insulin resistance and glucose intolerance. In addition, the lack of estrogen-mediated effects in numerous tissues of GPER KO mice, studied in vivo or ex vivo, including those of the cardiovascular, endocrine, nervous and immune systems, reveals GPER as a genuine mediator of estrogen action. Importantly, GPER KO mice have also demonstrated roles for GPER in breast carcinogenesis and metastasis. In combination with the supporting effects of GPER-selective ligands and GPER knockdown approaches, GPER KO mice demonstrate the therapeutic potential of targeting GPER activity in diseases as diverse as obesity, diabetes, multiple sclerosis, hypertension, atherosclerosis, myocardial infarction, stroke and cancer.

R-flurbiprofen attenuates experimental autoimmune encephalomyelitis in mice

R-flurbiprofen is the non-cyclooxygenase inhibiting R-enantiomer of the non-steroidal anti-inflammatory drug flurbiprofen, which was assessed as a remedy for Alzheimer's disease. Because of its anti-inflammatory, endocannabinoid-modulating and antioxidative properties, combined with low toxicity, the present study assessed R-flurbiprofen in experimental autoimmune encephalomyelitis (EAE) models of multiple sclerosis in mice. Oral R-flurbiprofen prevented and attenuated primary progressive EAE in C57BL6/J mice and relapsing-remitting EAE in SJL mice, even if the treatment was initiated on or after the first flare of the disease. R-flurbiprofen reduced immune cell infiltration and microglia activation and inflammation in the spinal cord, brain and optic nerve and attenuated myelin destruction and EAE-evoked hyperalgesia. R-flurbiprofen treatment increased CD4(+)CD25(+)FoxP3(+) regulatory T cells, CTLA4(+) inhibitory T cells and interleukin-10, whereas the EAE-evoked upregulation of pro-inflammatory genes in the spinal cord was strongly reduced. The effects were associated with an increase of plasma and cortical endocannabinoids but decreased spinal prostaglandins, the latter likely due to R to S inversion. The promising results suggest potential efficacy of R-flurbiprofen in human MS, and its low toxicity may justify a clinical trial.

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.

Disruption of estrous cycle homeostasis in mice with experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is widely viewed as a prototypic human autoimmune disease involving proinflammatory T cells that induce lesions in the central nervous system (CNS) in response to myelin self proteins. Although the impact of sex hormones on MS is well recognized, the converse effects of autoimmunity on sex hormones are still unclear. The current study was designed to assess the impact of CNS autoimmunity on female reproductive physiology. In order to identify subtle hormonal disturbances as a result of autoimmunity, we analyzed the estrous cycle in SJL/J mice after active induction of experimental autoimmune encephalomyelitis (EAE), an animal model with substantial similarities to MS. Here we show that CNS autoimmunity significantly shortens the murine estrous cycle. This shortening of the estrous cycle is characterized by a dramatic decrease in the length of the metestrus-diestrus luteal phase partially offset by a highly significant but less dramatic elongation of the proestrus-estrus follicular phase of the uterine cycle. Thus, our study provides experimental evidence for a direct causal link between CNS autoimmunity and disruption of the homeostatic balance of the uterine cycle often observed in women with MS.

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.

Long-term influence of combined oral contraceptive use on the clinical course of relapsing-remitting multiple sclerosis

OBJECTIVE

To assess the long-term effects of combined oral contraceptives (COCs) on the clinical course of relapsing-remitting multiple sclerosis (RRMS), focusing on disability progression and evolution to secondary-progressive multiple sclerosis (SPMS).

DESIGN

Retrospective and exploratory study.

SETTING

Academic medical center.

PATIENT(S)

A total of 174 women with clinically confirmed MS; of these, 33 had evolved to SPMS at the time of enrollment in the study, whereas 141 still had a relapsing-remitting form of disease.

INTERVENTION(S)

Women were interviewed to obtain gynecologic and obstetric history.

MAIN OUTCOME MEASURE(S)

Expanded Disability Status Scale (EDSS); Multiple Sclerosis Severity Score (MSSS); annualized relapse rate; evolution to SPMS.

RESULT(S)

Mean±SD duration of disease was 14.3±9.8 years. Compared with non-users of COCs, COC users had lower EDSS scores and MSSS only in the subset of the population with prior or current immunomodulatory treatment. Nonuse of COCs was a predictor of disease evolution in SPMS, whether treated or not with immunomodulatory drugs. The annualized relapse rate was not influenced by COC use. No differences in EDSS scores and evolution to SPMS depending on COC formulation were detected.

CONCLUSION(S)

Our results suggest that COC use is associated with a less severe disease and less severe evolution. Whether different doses or types of progestin may have different effects remains to be defined.

Neuroendocrine immunoregulation in multiple sclerosis

Currently, it is generally accepted that multiple sclerosis (MS) is a complex multifactorial disease involving genetic and environmental factors affecting the autoreactive immune responses that lead to damage of myelin. In this respect, intrinsic or extrinsic factors such as emotional, psychological, traumatic, or inflammatory stress as well as a variety of other lifestyle interventions can influence the neuroendocrine system. On its turn, it has been demonstrated that the neuroendocrine system has immunomodulatory potential. Moreover, the neuroendocrine and immune systems communicate bidirectionally via shared receptors and shared messenger molecules, variously called hormones, neurotransmitters, or cytokines. Discrepancies at any level can therefore lead to changes in susceptibility and to severity of several autoimmune and inflammatory diseases. Here we provide an overview of the complex system of crosstalk between the neuroendocrine and immune system as well as reported dysfunctions involved in the pathogenesis of autoimmunity, including MS. Finally, possible strategies to intervene with the neuroendocrine-immune system for MS patient management will be discussed. Ultimately, a better understanding of the interactions between the neuroendocrine system and the immune system can open up new therapeutic approaches for the treatment of MS as well as other autoimmune diseases.

Estrogen receptor-β ligand treatment after disease onset is neuroprotective in the multiple sclerosis model

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammation and neurodegeneration. Current MS treatments were designed to reduce inflammation in MS rather than directly to prevent neurodegeneration. Estrogen has well-documented neuroprotective effects in a variety of disorders of the CNS, including experimental autoimmune encephalomyelitis (EAE), the most widely used mouse model of MS. Treatment with an estrogen receptor-β (ERβ) ligand is known to ameliorate clinical disease effectively and provide neuroprotection in EAE. However, the protective effects of this ERβ ligand have been demonstrated only when administered prior to disease (prophylactically). Here we tested whether ERβ ligand treatment could provide clinical protection when treatment was initiated after onset of disease (therapeutically). We found that therapeutic treatment effectively ameliorated clinical disease in EAE. Specifically, ERβ ligand-treated animals exhibited preserved axons and myelin compared with vehicle-treated animals. We observed no difference in the number of T lymphocytes, macrophages, or microglia in the CNS of vehicle- vs. ERβ ligand-treated animals. Our findings show that therapeutically administered ERβ ligand successfully treats clinical EAE, bearing translational relevance to MS as a candidate neuroprotective agent.

Neuroactive steroids, their metabolites, and neuroinflammation

Neuroinflammation represents a common feature of many neurodegenerative diseases implicated both in their onset and progression. Neuroactive steroids act as physiological regulators and protective agents in the nervous system. Therefore, the attention of biomedical research has been recently addressed in evaluating whether neuroactive steroids, such as progestagens, androgens, and estrogens may also affect neuroinflammatory pathways. Observations so far obtained suggest a general anti-inflammatory effect with a beneficial relapse on several neurodegenerative experimental models, thus confirming the potentiality of a neuroprotective strategy based on neuroactive steroids. In this scenario, neuroactive steroid metabolism and the sophisticated machinery involved in their signaling are becoming especially attractive. In particular, because metabolism of neuroactive steroids as well as expression of their receptors is affected during the course of neurodegenerative events, a crucial role of progesterone and testosterone metabolites in modulating neuroinflammation and neurodegeneration may be proposed. In the present review, we will address this issue, providing evidence supporting the hypothesis that the efficacy of neuroactive steroids could be improved through the use of their metabolites.

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.

Progesterone synthesis in the nervous system: implications for myelination and myelin repair

Progesterone is well known as a female reproductive hormone and in particular for its role in uterine receptivity, implantation, and the maintenance of pregnancy. However, neuroendocrine research over the past decades has established that progesterone has multiple functions beyond reproduction. Within the nervous system, its neuromodulatory and neuroprotective effects are much studied. Although progesterone has been shown to also promote myelin repair, its influence and that of other steroids on myelination and remyelination is relatively neglected. Reasons for this are that hormonal influences are still not considered as a central problem by most myelin biologists, and that neuroendocrinologists are not sufficiently concerned with the importance of myelin in neuron functions and viability. The effects of progesterone in the nervous system involve a variety of signaling mechanisms. The identification of the classical intracellular progesterone receptors as therapeutic targets for myelin repair suggests new health benefits for synthetic progestins, specifically designed for contraceptive use and hormone replacement therapies. There are also major advantages to use natural progesterone in neuroprotective and myelin repair strategies, because progesterone is converted to biologically active metabolites in nervous tissues and interacts with multiple target proteins. The delivery of progesterone however represents a challenge because of its first-pass metabolism in digestive tract and liver. Recently, the intranasal route of progesterone administration has received attention for easy and efficient targeting of the brain. Progesterone in the brain is derived from the steroidogenic endocrine glands or from local synthesis by neural cells. Stimulating the formation of endogenous progesterone is currently explored as an alternative strategy for neuroprotection, axonal regeneration, and myelin repair.

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.

Current status of the immunomodulation and immunomediated therapeutic strategies for multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, and CD4(+) T cells form the core immunopathogenic cascade leading to chronic inflammation. Traditionally, Th1 cells (interferon-γ-producing CD4(+) T cells) driven by interleukin 12 (IL12) were considered to be the encephalitogenic T cells in MS and experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Currently, Th17 cells (Il17-producing CD4(+) T cells) are considered to play a fundamental role in the immunopathogenesis of EAE. This paper highlights the growing evidence that Th17 cells play the core role in the complex adaptive immunity of EAE/MS and discusses the roles of the associated immune cells and cytokines. These constitute the modern immunological basis for the development of novel clinical and preclinical immunomodulatory therapies for MS discussed in this paper.

Estrogen-induced protection against experimental autoimmune encephalomyelitis is abrogated in the absence of B cells

Increased remissions in multiple sclerosis (MS) during pregnancy suggest that elevated levels of sex steroids exert immunoregulatory activity. Estrogen (E2=17β-estradiol) protects against experimental autoimmune encephalomyelitis (EAE), but the cellular basis for E2-induced protection remains unclear. Studies demonstrate that depletion of B cells prior to induction of EAE exacerbates disease severity, implicating regulatory B cells. We thus evaluated pathogenic and E2-induced protective mechanisms in B-cell-deficient (μMT(-/-)) mice. EAE-protective effects of E2 were abrogated in μMT(-/-) mice, with no reduction in disease severity, cellular infiltration or pro-inflammatory factors in the central nervous system compared to untreated controls. E2 treatment of WT mice selectively upregulated expression of PD-L1 on B cells and increased the percentage of IL-10-producing CD1d(high) CD5(+) regulatory B cells. Upregulation of PD-L1 was critical for E2-mediated protection since E2 did not inhibit EAE in PD-L1(-/-) mice. Direct treatment of B cells with E2 significantly reduced proliferation of MOG(35-55)-specific T cells that required estrogen receptor-α (ERα). These results demonstrate, for the first time, a requirement for B cells in E2-mediated protection against EAE involving direct E2 effects on regulatory B cells mediated through ERα and the PD-1/PD-L1 negative co-stimulatory pathway. E2-primed B cells may represent an important regulatory mechanism in MS and have strong implications for women receiving current MS therapies that cause B-cell depletion.

Age at onset of multiple sclerosis is correlated to use of combined oral contraceptives and childbirth before diagnosis

The aim of this study was to evaluate whether age of onset of multiple sclerosis is related to use of combined oral contraceptives and/or timing of childbirth. The results showed that use of combined oral contraceptives and childbirth before the first multiple sclerosis symptom was correlated to a higher mean age at the onset of the disease.

New approaches in the management of multiple sclerosis

Multiple sclerosis (MS) is a central nervous system chronic inflammatory disease that is characterized by an extensive and complex immune response. Scientific advances have occurred in immunology, pathophysiology, and diagnostic and clinical assessment tools, and recent discovery of unique therapeutic targets has spurred numerous Phase II and Phase III clinical trials. Reductions in MS relapse rates and improvements in T₂ or gadolinium-enhancing lesion burdens have been reported from Phase III trials that include fingolimod, alemtuzumab, cladribine, and rituximab. Promising Phase II trial data exist for teriflunomide, daclizumab, laquinimod, and fumarate. The optimism created by these favorable findings must be tempered with evaluation of the adverse effect profile produced by these new agents. Given the discovery of progressive multifocal leukoencephalopathy with the use of natalizumab, ongoing vigilance for rare and life-threatening reactions due to new agents should be paramount. Patients with MS often experience difficulty with ambulation, spasticity, and cognition. Recent clinical trial data from two Phase III dalfampridine-SR trials indicate certain patients receive benefits in ambulation. This article provides an overview of data from clinical trials of newer agents of potential benefit in MS.

Induction of pregnancy during established EAE halts progression of CNS autoimmune injury via pregnancy-specific serum factors

Multiple sclerosis (MS) is a demyelinating disease of the CNS involving T cell targeting of myelin antigens. During pregnancy, women with MS experience decreased relapses followed by a post partum disease flare. Using murine experimental autoimmune encephalomyelitis, we recapitulate pregnancy findings in both relapsing and progressive models. Pregnant mice produced less TNF-α, IL-17 and exhibited reduced CNS pathology relative to non-pregnant controls. Microparticles, called exosomes, shed into the blood during pregnancy were isolated and found to significantly suppress T cell activation relative to those from non-pregnant controls. These results demonstrate the immunosuppressive potential of pregnancy and serum-derived pregnancy exosomes.

Estradiol inhibits ongoing autoimmune neuroinflammation and NFkappaB-dependent CCL2 expression in reactive astrocytes

Astroglial reactivity associated with increased production of NFkappaB-dependent proinflammatory molecules is an important component of the pathophysiology of chronic neurological disorders such as multiple sclerosis (MS). The use of estrogens as potential anti-inflammatory and neuroprotective drugs is a matter of debate. Using mouse experimental allergic encephalomyelitis (EAE) as a model of chronic neuroinflammation, we report that implants reproducing pregnancy levels of 17beta-estradiol (E2) alleviate ongoing disease and decrease astrocytic production of CCL2, a proinflammatory chemokine that drives the local recruitment of inflammatory myeloid cells. Immunohistochemistry and confocal imaging reveal that, in spinal cord white matter EAE lesions, reactive astrocytes express estrogen receptor (ER)alpha (and to a lesser extent ERbeta) with a preferential nuclear localization, whereas other cells including infiltrated leukocytes express ERs only in their membranes or cytosol. In cultured rodent astrocytes, E2 or an ERalpha agonist, but not an ERbeta agonist, inhibits TNFalpha-induced CCL2 expression at nanomolar concentrations, and the ER antagonist ICI 182,170 blocks this effect. We show that this anti-inflammatory action is not associated with inhibition of NFkappaB nuclear translocation but rather involves direct repression of NFkappaB-dependent transcription. Chromatin immunoprecipitation assays further indicate that estrogen suppresses TNFalpha-induced NFkappaB recruitment to the CCL2 enhancer. These data uncover reactive astrocytes as an important target for nuclear ERalpha inhibitory action on chemokine expression and suggest that targeting astrocytic nuclear NFkappaB activation with estrogen receptor alpha modulators may improve therapies of chronic neurodegenerative disorders involving astroglial neuroinflammation.

Nuclear receptors, inflammation, and neurodegenerative diseases

Chronic inflammation is associated with many neurodegenerative diseases, including multiple sclerosis, Parkinson's disease, and Alzheimer's disease. Increasing evidence that neuroinflammation contributes to disease severity has generated considerable interest in determining whether inhibition of inflammation pathways might be of therapeutic benefit. One potential avenue of intervention is provided by members of the nuclear receptor superfamily of ligand-dependent transcription factors that exert anti-inflammatory effects in many cell types. Here, we review recent studies providing insights into the distinct mechanisms that enable nuclear receptors to modulate immune responses, describe inflammatory components of neurodegenerative diseases, and discuss recent literature relevant to roles of nuclear receptors in influencing these processes.

Additive effects of combination treatment with anti-inflammatory and neuroprotective agents in experimental autoimmune encephalomyelitis

We studied the effects of combination treatment with an anti-inflammatory agent, interferon (IFN)-beta, and a putative neuroprotective agent, an estrogen receptor (ER)-beta ligand, during EAE. Combination treatment significantly attenuated EAE disease severity, preserved axonal densities in spinal cord, and reduced CNS inflammation. Combining ERbeta treatment with IFNbeta reduced IL-17, while it abrogated IFNbeta-mediated increases in Th1 and Th2 cytokines from splenocytes. Additionally, combination treatment reduced VLA-4 expression on CD4+ T cells, while it abrogated IFNbeta-mediated decreases in MMP-9. Our data demonstrate that combination treatments can result in complex effects that could not have been predicted based on monotherapy data alone.

Estrogen controls vitamin D3-mediated resistance to experimental autoimmune encephalomyelitis by controlling vitamin D3 metabolism and receptor expression

Multiple sclerosis (MS) is an autoimmune, neurodegenerative disease with a rapidly increasing female gender bias. MS prevalence decreases with increasing sunlight exposure, supporting our hypothesis that the sunlight-dependent hormone 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) is a natural inhibitor of autoimmune T cell responses in MS. We found that vitamin D(3) inhibited experimental autoimmune encephalomyelitis (EAE) in intact female mice, but not in ovariectomized females or males. To learn whether 17beta-estradiol (E(2)) is essential for vitamin D(3)-mediated protection, ovariectomized female mice were given E(2) or placebo and evaluated for vitamin D(3)-mediated EAE resistance. Diestrus-level E(2) implants alone provided no benefit, but they restored vitamin D(3)-mediated EAE resistance in the ovariectomized females. Synergy between E(2) and vitamin D(3) occurred through vitamin D(3)-mediated enhancement of E(2) synthesis, as well as E(2)-mediated enhancement of vitamin D receptor expression in the inflamed CNS. In males, E(2) implants did not enable vitamin D(3) to inhibit EAE. The finding that vitamin D(3)-mediated protection in EAE is female-specific and E(2)-dependent suggests that declining vitamin D(3) supplies due to sun avoidance might be contributing to the rapidly increasing female gender bias in MS. Moreover, declining E(2) synthesis and vitamin D(3)-mediated protection with increasing age might be contributing to MS disease progression in older women.

Congruent Effects of Estrogen and T-Cell Receptor Peptide Therapy on Regulatory T Cells in EAE and MS

Both estrogen (E2) and T-cell receptor (TCR) peptides have beneficial effects on the clinical course of experimental autoimmune encephalomyelitis (EAE) and possibly multiple sclerosis (MS) that involve distinct but congruent mechanisms. Of interest, these two approaches share an ability to enhance expression of the FoxP3 gene and associated activity of regulatory T (Treg) cells. E2 increases the number and activity of FoxP3(+) T cells through Esr-1 signaling during TCR activation of CD4(+)CD25(-) T cells. In contrast, TCR peptide therapy appears to increase the frequency of regulatory FoxP3(+) T cells specific for self-TCR determinants expressed by targeted pathogenic T cells. The combined effects on Treg expansion and activation induced by these distinct immunoregulatory approaches may account for their potent effects on clinical EAE and argue for a similar combined therapeutic approach for MS.

Impact of sex steroids on neuroinflammatory processes and experimental multiple sclerosis

Synthetic and natural estrogens as well as progestins modulate neuronal development and activity. Neurons and glia are endowed with high-affinity steroid receptors. Besides regulating brain physiology, both steroids conciliate neuroprotection against toxicity and neurodegeneration. The majority of data derive from in vitro studies, although more recently, animal models have proven the efficaciousness of steroids as neuroprotective factors. Indications for a safeguarding role also emerge from first clinical trials. Gender-specific prevalence of degenerative disorders might be associated with the loss of hormonal activity or steroid malfunctions. Our studies and evidence from the literature support the view that steroids attenuate neuroinflammation by reducing the pro-inflammatory property of astrocytes. This effect appears variable depending on the brain region and toxic condition. Both hormones can individually mediate protection, but they are more effective in cooperation. A second research line, using an animal model for multiple sclerosis, provides evidence that steroids achieve remyelination after demyelination. The underlying cellular mechanisms involve interactions with astroglia, insulin-like growth factor-1 responses, and the recruitment of oligodendrocytes.

Matrix metalloproteinase-12 deficiency worsens relapsing-remitting experimental autoimmune encephalomyelitis in association with cytokine and chemokine dysregulation

The elevation of several members of the matrix metalloproteinase (MMP) family promotes the pathophysiology of both multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). Nonetheless, given the multiple activities of MMPs, it remains possible that increased levels of a particular MMP may have beneficial functions during disease progression. We reported previously that MMP-12(-/-) mice of the 129/SvEv strain had a poorer EAE outcome than wild-type controls. However, we did not determine further differences in disease profiles between these groups. Using the EAE model in 129/SvEv mice, we report that disease in both wild-type and MMP-12(-/-) mice follows a relapsing-remitting course. Although both mouse groups had similar clinical onsets, subsequent relapses were more severe in MMP-12(-/-) mice; their residual disability at remission was also higher compared with wild-type controls. The worsened relapses and remissions in MMP-12(-/-) mice occurred despite a deficiency of the antigen recall capacity of lymph node-derived cells as well as a reduction in the proportion of macrophages in the spinal cord during the chronic phase of EAE. Significantly, large increases of levels of chemokines and cytokines were found in the spinal cords of MMP-12(-/-) mice during chronic EAE. These results highlight MMP-12 as a beneficial enzyme in EAE and suggest that therapeutic interventions in multiple sclerosis should avoid targeting MMP-12.

In vitro and in vivo pharmacological models to assess demyelination and remyelination

In making a selection of cellular tools and animal models for generating screening assays in the search for new drugs, one needs to take into consideration the practicality of their use in the drug discovery process. Conducting high-throughput primary screens using libraries of small molecules, close to 1 million members in size, requires the generation of large numbers of cells which are easily acquired, reliably enriched, and reproducibly responsive to standard positive controls. These cells need to be similar in form and function to their counterparts in human disease. In vitro assays that can be mechanized by using robots can therefore save time and costs. In selecting in vivo models, consideration must be given to the species and strain of animal chosen, the appropriateness of the model to human disease, the extent of animal husbandry required during the in-life pharmacological assessment, the technical aspects of generating the model and harvesting the tissues for analyses, the cost of research tools in terms of time and money (demyelinating and remyelinating agents, amount of compound to be generated), and the length of time required for drug testing in the model. A consideration of the translational aspects of the in vivo model compared to those used in the clinic is also important. These themes will be developed with examples for drug discovery in the field of CNS demyelination and repair, specifically as it pertains to multiple sclerosis.

Gender and sex hormones in multiple sclerosis pathology and therapy

Several lines of evidence indicate that gender affects the susceptibility and course of multiple sclerosis (MS) with a higher disease prevalence and overall better prognosis in women than men. This sex dimorphism may be explained by sex chromosome effects and effects of sex steroid hormones on the immune system, blood brain barrier or parenchymal central nervous system (CNS) cells. The well known improvement in disease during late pregnancy has also been linked to hormonal changes and has stimulated recent clinical studies to determine the efficacy of and tolerance to sex steroid therapeutic approaches. Both clinical and experimental studies indicate that sex steroid supplementation may be beneficial for MS. This could be related to anti-inflammatory actions on the immune system or CNS and to direct neuroprotective properties. Here, clinical and experimental data are reviewed with respect to the effects of sex hormones or gender in the pathology or therapy of MS or its rodent disease models. The different cellular targets as well as some molecular mechanisms likely involved are discussed.

Nitric oxide mediates the suppressive effect of testosterone on cell proliferative response to myelin basic protein

This study assessed whether the in vitro effect of testosterone on the proliferative response of mononuclear cells to myelin basic protein (MBP) could be mediated by nitric oxide (NO). Testosterone but not cholesterol supplementation specifically suppressed the proliferative response of rat mononuclear cells to MBP and in parallel increased the NO level. NG-monomethyl 1-l-arginine, an inhibitor of NO synthesis, reverted the suppression of the testosterone-induced proliferative response to MBP. These results indicate that changes in the production of NO by testosterone are able to alter the specific T cell proliferation induced by the encephalitogenic MBP and in this way; it could be one of the molecular mechanisms that modulate the development of experimental autoimmune encephalomyelitis (EAE).

Soluble epoxide hydrolase: regulation by estrogen and role in the inflammatory response to cerebral ischemia

The protection from ischemic brain injury enjoyed by females is linked to the female sex hormone 17beta-estradiol. We tested the hypothesis that neuroprotection by estradiol entails the prevention of ischemia-induced inflammatory response, through suppression of the P450 eicosanoids-metabolizing enzyme soluble epoxide hydrolase (sEH). Ovariectomized female rats with and without estradiol replacement underwent 2-hour middle cerebral artery occlusion (MCAO). SEH expression was determined using Western blot, and inflammatory cytokine mRNA levels were measured at 6, 24 and 48 hours after MCAO. Cytokine mRNA was also measured in sEH-knockout mice, and in rats treated with sEH inhibitors. Estradiol reduced basal and post-ischemic sEH expression. MCAO strongly induced mRNA levels of tumor necrosis factor-alpha, interleukin 6, and interleukin 1beta, which was attenuated in sEH-knockouts, but not by sEH inhibitors. Estradiol replacement exhibited a bimodal effect on cytokine mRNA, with increased early and reduced delayed expression. While estradiol suppresses cerebral sEH expression, and sEH suppression diminishes inflammation after MCAO, our findings suggest that the effect of estrogen on inflammation is complex, and only partially explained by sEH suppression.

Downregulation of macrophage inhibitory molecules in multiple sclerosis lesions

OBJECTIVE

Inflammatory and demyelinating activity of activated resident macrophages (microglia) and recruited blood-borne macrophages are considered crucial in multiple sclerosis (MS) lesion development. The membrane glycoproteins CD200 and CD47, highly expressed on neurons, are mediators of macrophage inhibition via their receptors CD200R and signal-regulatory protein alpha, respectively, on myeloid cells. We determined the expression pattern of immune inhibitory molecules in relation to genes involved in macrophage activation and MS lesion pathology.

METHODS

Laser dissection microscopy was combined with real-time polymerase chain reaction to quantitatively study these gene expression patterns in specific subareas (rim, center, and normal-appearing white matter) of chronic active and inactive MS lesions.

RESULTS

Hallmarks of MS pathology were confirmed by messenger RNA expression patterns of glial fibrillary acidic protein, neurofilament (NF), myelin basic protein, growth factors, chemokines and receptors, and macrophage activation markers, although expression of osteopontin and alphaB-crystallin was decreased. CD200 and CD47 were downregulated in the center of chronic active and inactive MS lesions. CD47 expression was also decreased in the rim of chronic active lesions, where complement expression was increased. This expression profile was also found in normal-appearing white matter surrounding these lesions, but not surrounding inactive lesions. Expression of CD200R and signal-regulatory protein alpha was not altered.

INTERPRETATION

These data suggest that diminished immune inhibition via decreased CD200 and CD47 expression contributes to a disturbed equilibrium in macrophage and microglia activation in MS lesions. Furthermore, this may result in a proinflammatory predisposition in the area surrounding chronic active lesions, thereby contributing to axonal injury, demyelination, and possible lesion expansion.