Estrogen treatment decreases matrix metalloproteinase (MMP)-9 in autoimmune demyelinating disease through estrogen receptor alpha (ERalpha).

Matrix metalloproteinases (MMPs) have a crucial function in migration of inflammatory cells into the central nervous system (CNS). Levels of MMP-9 are elevated in multiple sclerosis (MS) and predict the occurrence of new active lesions on magnetic resonance imaging (MRI). This translational study aims to determine whether in vivo treatment with the pregnancy hormone estriol affects MMP-9 levels from immune cells in patients with MS and mice with experimental autoimmune encephalomyelitis (EAE). Peripheral blood mononuclear cells (PBMCs) collected from three female MS patients treated with estriol and splenocytes from EAE mice treated with estriol, estrogen receptor (ER) alpha ligand, ERbeta ligand or vehicle were stimulated ex vivo and analyzed for levels of MMP-9. Markers of CNS infiltration were assessed using MRI in patients and immunohistochemistry in mice. Supernatants from PBMCs obtained during estriol treatment in female MS patients showed significantly decreased MMP-9 compared with pretreatment. Decreases in MMP-9 coincided with a decrease in enhancing lesion volume on MRI. Estriol treatment of mice with EAE reduced MMP-9 in supernatants from autoantigen-stimulated splenocytes, coinciding with decreased CNS infiltration by T cells and monocytes. Experiments with selective ER ligands showed that this effect was mediated through ERalpha. In conclusion, estriol acting through ERalpha to reduce MMP-9 from immune cells is one mechanism potentially underlying the estriol-mediated reduction in enhancing lesions in MS and inflammatory lesions in EAE

A role for sex chromosome complement in the female bias in autoimmune disease

Most autoimmune diseases are more common in women than in men. This may be caused by differences in sex hormones, sex chromosomes, or both. In this study, we determined if there was a contribution of sex chromosomes to sex differences in susceptibility to two immunologically distinct disease models, experimental autoimmune encephalomyelitis (EAE) and pristane-induced lupus. Transgenic SJL mice were created to permit a comparison between XX and XY within a common gonadal type. Mice of the XX sex chromosome complement, as compared with XY, demonstrated greater susceptibility to both EAE and lupus. This is the first evidence that the XX sex chromosome complement, as compared with XY, confers greater susceptibility to autoimmune disease

Oestrogen receptor β ligand: a novel treatment to enhance endogenous functional remyelination

Demyelinating diseases, such as multiple sclerosis, are characterized by inflammatory demyelination and neurodegeneration of the central nervous system. Therapeutic strategies that induce effective neuroprotection and enhance intrinsic repair mechanisms are central goals for future therapy of multiple sclerosis. Oestrogens and oestrogen receptor ligands are promising treatments to prevent multiple sclerosis-induced neurodegeneration. In the present study we investigated the capacity of oestrogen receptor β ligand treatment to affect callosal axon demyelination and stimulate endogenous myelination in chronic experimental autoimmune encephalomyelitis using electrophysiology, electron microscopy, immunohistochemistry and tract-tracing methods. Oestrogen receptor β ligand treatment of experimental autoimmune encephalomyelitis mice prevented both histopathological and functional abnormalities of callosal axons despite the presence of inflammation. Specifically, there were fewer demyelinated, damaged axons and more myelinated axons with intact nodes of Ranvier in oestrogen receptor β ligand-treated mice. In addition, oestrogen receptor β ligand treatment caused an increase in mature oligodendrocyte numbers, a significant increase in myelin sheath thickness and axon transport. Functional analysis of callosal axon conduction showed a significant improvement in compound action potential amplitudes, latency and in axon refractoriness. These findings show a direct neuroprotective effect of oestrogen receptor β ligand treatment on oligodendrocyte differentiation, myelination and axon conduction during experimental autoimmune encephalomyelitis

Parent-of-Origin Sex Chromosome Effects on the Immune and Central Nervous System During Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is an autoimmune demyelinating disease characterized by increased susceptibility in women. However, when men get the disease, they demonstrate more rapid disease progression, thus presenting a clinical enigma of the pathogenic events in MS susceptibility and progression. Of the sex-related factors that may contribute to MS susceptibility, much of the literature on the MS model, experimental autoimmune encephalitomyelits (EAE), has focused on the role of sex hormones in immune responses. While sex hormones have been demonstrated to affect autoimmune responses and neurodegeneration in EAE, it does not preclude sex chromosome effects. Indeed, previous work from our lab has demonstrated that the sex chromosome complement of immune cells affected autoimmune responses, with the XX sex chromosome complement, as compared to XY, leading to greater encephalitogenicity during auto-antigen stimulation. These results are consistent with human clinical observations of increased autoimmunity in women vs. men. This dissertation builds upon this finding by exploring the nature of sex chromosome effects in the female bias in autoimmunity through the use of transgenic sex chromosome mouse models that include the following genotypes: XX, XY-, XmY*x and XpY*x. Through a series of experiments, I demonstrate that parental imprinting of the X chromosome gene, forkhead box P3 (Foxp3), a master-regulator of T regulatory (Treg) cell development, results in increased FoxP3+ Tregs in XY- mice vs. XX mice.While sex chromosome effects have been identified in the immune system, it remained unclear if there were separate sex chromosome effects in the target organ, the CNS, response to an immune attack during EAE. This question is addressed in another portion of my dissertation. I created a bone marrow chimera model with mice bearing a common immune system, but varying sex chromosome complement in the CNS using the aforementioned transgenic sex chromosome mouse models, to examine the effects of sex chromosomes in the CNS during neurodegeneration. Through a series of experiments, I demonstrated that mice with CNS cells expressing XY sex chromosome complement, as compared to XX, led to greater neurodegeneration. Further, increased neurodegenerative response in the XY CNS was due to the maternal X allele. Together, these results demonstrated for the first time an affect of parental imprinting resulting in female bias on the autoimmune responses, and male bias in neurodegeneration during EAE. These findings may bear relevance to the clinical observations of female bias in susceptibility, but increased disability progression in men with MS

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

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

Relative expression of myogenic differentiation factor D (MyoD) mRNA in the manakin testosterone (T) treatment study, zebra finch flutamide treatment study, and the species comparison study.

<p>(A) Manakin T treatment study; white-bars represent male manakins treated with T-filled implants, and black bars represent male manakins treated with blank implants (Control). (B) Zebra finch flutamide study; white bars represent male zebra finches treated with T-filled implants and blank implants (T+Blank), and black bars represent male zebra finches treated with T-filled implants and flutamide-filled implants (T+Flutamide). (C) Species comparison of reproductively active male birds. White bars represent golden-collared manakins, grey bars represent ochre-bellied flycatchers, and black bars represent zebra finches. Wing muscles are displayed on the horizontal axis in all graphs (<i>supracoracoideus</i> = SC; <i>scapulohumeralis caudalis</i> = SH; and <i>pectoralis</i> = PEC). Non-significant differences between hormone manipulated groups (A & B) are denoted by the abbreviation <i>N.S.</i> within each graph’s legend, whereas significant differences among species (C) are denoted by an asterisks (*) displayed within the legend. Data represent means ±1 SEM.</p

Species-specific quantitative PCR (qPCR) primers.

<p>Species-specific quantitative PCR (qPCR) primers.</p

PCR primers generated from zebra finch genome.

<p>PCR primers generated from zebra finch genome.</p