Multiple Sclerosis Articles 2

© 2010

Dysregulation of the hypothalamic-pituitary-gonadal axis in experimental autoimmune encephalomyelitis and multiple sclerosis

(Foster, Daniels et al. 2003) Download

The ability of sex hormones to regulate cytokine production is well established, but the ability of cytokines to regulate sex hormone production has only begun to be investigated. We measured sex hormones in mice with passive experimental autoimmune encephalomyelitis (EAE) and in multiple sclerosis (MS) patients with sexual dysfunction. Abnormally low serum testosterone levels were found in male mice with EAE and in male MS patients, while serum estrogen levels in female mice with EAE were normal. An inverse relationship between cytokine and testosterone levels in male mice with EAE, coupled with an increase in serum luteinizing hormone (LH) levels, suggests that inflammatory cytokines suppress testosterone production by a direct effect on testicular Leydig cells. Gender differences in the sensitivity of the hypothalamic-pituitary-gonadal (HPG) axis to inflammation may be an important factor regulating the duration and severity of central nervous system (CNS) autoimmunity.

Estrogen receptor alpha mediates estrogen's immune protection in autoimmune disease

(Liu, Loo et al. 2003) Download

Estrogens are known to influence a variety of autoimmune diseases, but it is not known whether their actions are mediated through classic estrogen receptor alpha (ERalpha). The presence of a functional ER was demonstrated in secondary lymphoid tissues, then ERalpha expression was shown at both the RNA and protein levels in these tissues. Use of ERalpha knockout mice revealed that both the estrogen-induced disease protection and the estrogen-induced reduction in proinflammatory cytokines were dependent upon ERalpha in the prototypic Th1-mediated autoimmune disease experimental autoimmune encephalomyelitis. These findings are central to the design of selective ER modifiers which aim to target biologic responses in specific organ systems.

Treatment of multiple sclerosis with the pregnancy hormone estriol

            (Sicotte, Liva et al. 2002) Download

Multiple sclerosis patients who become pregnant experience a significant decrease in relapses that may be mediated by a shift in immune responses from T helper 1 to T helper 2. Animal models of multiple sclerosis have shown that the pregnancy hormone, estriol, can ameliorate disease and can cause an immune shift. We treated nonpregnant female multiple sclerosis patients with the pregnancy hormone estriol in an attempt to recapitulate the beneficial effect of pregnancy. As compared with pretreatment baseline, relapsing remitting patients treated with oral estriol (8 mg/day) demonstrated significant decreases in delayed type hypersensitivity responses to tetanus, interferon-gamma levels in peripheral blood mononuclear cells, and gadolinium enhancing lesion numbers and volumes on monthly cerebral magnetic resonance images. When estriol treatment was stopped, enhancing lesions increased to pretreatment levels. When estriol treatment was reinstituted, enhancing lesions again were significantly decreased. Based on these results, a larger, placebo-controlled trial of estriol is warranted in women with relapsing remitting multiple sclerosis. This novel treatment strategy of using pregnancy doses of estriol in multiple sclerosis has relevance to other autoimmune diseases that also improve during pregnancy.

Neuroprotection by estradiol

            (Garcia-Segura, Azcoitia et al. 2001) Download

This review highlights recent evidence from clinical and basic science studies supporting a role for estrogen in neuroprotection. Accumulated clinical evidence suggests that estrogen exposure decreases the risk and delays the onset and progression of Alzheimer's disease and schizophrenia, and may also enhance recovery from traumatic neurological injury such as stroke. Recent basic science studies show that not only does exogenous estradiol decrease the response to various forms of insult, but the brain itself upregulates both estrogen synthesis and estrogen receptor expression at sites of injury. Thus, our view of the role of estrogen in neural function must be broadened to include not only its function in neuroendocrine regulation and reproductive behaviors, but also to include a direct protective role in response to degenerative disease or injury. Estrogen may play this protective role through several routes. Key among these are estrogen dependent alterations in cell survival, axonal sprouting, regenerative responses, enhanced synaptic transmission and enhanced neurogenesis. Some of the mechanisms underlying these effects are independent of the classically defined nuclear estrogen receptors and involve unidentified membrane receptors, direct modulation of neurotransmitter receptor function, or the known anti-oxidant activities of estrogen. Other neuroprotective effects of estrogen do depend on the classical nuclear estrogen receptor, through which estrogen alters expression of estrogen responsive genes that play a role in apoptosis, axonal regeneration, or general trophic support. Yet another possibility is that estrogen receptors in the membrane or cytoplasm alter phosphorylation cascades through direct interactions with protein kinases or that estrogen receptor signaling may converge with signaling by other trophic molecules to confer resistance to injury. Although there is clear evidence that estradiol exposure can be deleterious to some neuronal populations, the potential clinical benefits of estrogen treatment for enhancing cognitive function may outweigh the associated central and peripheral risks. Exciting and important avenues for future investigation into the protective effects of estrogen include the optimal ligand and doses that can be used clinically to confer benefit without undue risk, modulation of neurotrophin and neurotrophin receptor expression, interaction of estrogen with regulated cofactors and coactivators that couple estrogen receptors to basal transcriptional machinery, interactions of estrogen with other survival and regeneration promoting factors, potential estrogenic effects on neuronal replenishment, and modulation of phenotypic choices by neural stem cells.

Minireview: neuroprotective effects of estrogen-new insights into mechanisms of action

            (Wise, Dubal et al. 2001) Download

An accumulating body of evidence clearly establishes that estradiol is a potent neuroprotective and neurotrophic factor in the adult: it influences memory and cognition, decreases the risk and delays the onset of neurological diseases such as Alzheimer's disease, and attenuates the extent of cell death that results from brain injuries such as cerebrovascular stroke and neurotrauma. Thus, estradiol appears to act at two levels: 1) it decreases the risk of disease or injury; and/or 2) it decreases the extent of injury incurred by suppressing the neurotoxic stimulus itself or increasing the resilience of the brain to a given injury. During the past century, the average life span of women has increased dramatically, whereas the time of the menopause has remained essentially constant. Thus, more women will live a larger fraction of their lives in a postmenopausal, hypoestrogenic state than ever before. Clearly, it is critical for us understand the circumstances under which estradiol exerts protective actions and the cellular and molecular mechanisms that underlie these novel, nonreproductive actions.

Memory retention is modulated by acute estradiol and progesterone replacement

            (Sandstrom and Williams 2001) Download

Ovarian hormones alter spine density of hippocampal granule and pyramidal cells in young adult and aging female rats (P. Miranda, C. L. Williams, & G. Einstein, 1999; C. S. Woolley, 1998). The present study used a delayed matching-to-place version of the water maze to investigate a behavioral correlate of these hormone-induced changes in hippocampal connectivity in 3- and 8-month-old female rats. When primed with 10-microg injections of estradiol 72 and 48 hr before testing, the memory retention of ovariectomized rats was improved compared with retention after priming with oil. A single injection of progesterone maintained this enhancement if testing occurred within 8 hr of the progesterone injection but not if testing occurred more than 24 hr after the progesterone injection. These findings indicate that estradiol and progesterone alter memory retention and suggest that these changes may be the result of hormone-induced increases in hippocampal connectivity.

Estrogen receptor alpha, not beta, is a critical link in estradiol-mediated protection against brain injury

(Dubal, Zhu et al. 2001) Download

Estradiol protects against brain injury, neurodegeneration, and cognitive decline. Our previous work demonstrates that physiological levels of estradiol protect against stroke injury and that this protection may be mediated through receptor-dependent alterations of gene expression. In this report, we tested the hypothesis that estrogen receptors play a pivotal role in mediating neuroprotective actions of estradiol and dissected the potential biological roles of each estrogen receptor (ER) subtype, ER alpha and ER beta, in the injured brain. To investigate and delineate these mechanisms, we used ER alpha-knockout (ER alpha KO) and ER beta-knockout (ER beta KO) mice in an animal model of stroke. We performed our studies by using a controlled endocrine paradigm, because endogenous levels of estradiol differ dramatically among ER alpha KO, ER beta KO, and wild-type mice. We ovariectomized ER alpha KO, ER beta KO, and the respective wild-type mice and implanted them with capsules filled with oil (vehicle) or a dose of 17 beta-estradiol that produces physiological hormone levels in serum. One week later, mice underwent ischemia. Our results demonstrate that deletion of ER alpha completely abolishes the protective actions of estradiol in all regions of the brain; whereas the ability of estradiol to protect against brain injury is totally preserved in the absence of ER beta. Thus, our results clearly establish that the ER alpha subtype is a critical mechanistic link in mediating the protective effects of physiological levels of estradiol in brain injury. Our discovery that ER alpha mediates protection of the brain carries far-reaching implications for the selective targeting of ERs in the treatment and prevention of neural dysfunction associated with normal aging or brain injury.

Testosterone acts directly on CD4+ T lymphocytes to increase IL-10 production

(Liva and Voskuhl 2001) Download

Males are less susceptible than females to experimental autoimmune encephalomyelitis and many other autoimmune diseases. Gender differences in cytokine production have been observed in splenocytes of experimental autoimmune encephalomyelitis mice stimulated with myelin proteins and may underlie gender differences in susceptibility. As these differences should not be limited to responses specific for myelin proteins, gender differences in cytokine production upon stimulation with Ab to CD3 were examined, and the mechanisms were delineated. Splenocytes from male mice stimulated with Ab to CD3 produced more IL-10 and IL-4 and less IL-12 than those from female mice. Furthermore, splenocytes from dihydrotestosterone (DHT)-treated female mice produced more IL-10 and less IL-12 than those from placebo-treated female mice, whereas there was no difference in IL-4. IL-12 knockout mice were then used to determine whether changes in IL-10 production were mediated directly by testosterone vs indirectly by changes in IL-12. The results of these experiments favored the first hypothesis, because DHT treatment of female IL-12 knockout mice increased IL-10 production. To begin to delineate the mechanism by which DHT may be acting, the cellular source of IL-10 was determined. At both the RNA and protein levels, IL-10 was produced primarily by CD4+ T lymphocytes. CD4+ T lymphocytes were then shown to express the androgen receptor, raising the possibility that testosterone acts directly on CD4+ T lymphocytes to increase IL-10 production. In vitro experiments demonstrated increased IL-10 production following treatment of CD4+ T lymphocytes with DHT. Thus, testosterone can act directly via androgen receptors on CD4+ T lymphocytes to increase IL-10 gene expression.

Estriol ameliorates autoimmune demyelinating disease

            (Kim, Liva et al. 1999) Download

OBJECTIVE: To evaluate the use of estriol in the treatment of experimental autoimmune encephalomyelitis (EAE) and other cell mediated autoimmune diseases. BACKGROUND: Experimental autoimmune encephalomyelitis is a T helper 1 (Th1)-mediated autoimmune demyelinating disease that is a useful model for the study of immune responses in MS. Interestingly, both EAE and MS have been shown to be ameliorated during late pregnancy. METHODS: Estriol, progesterone, and placebo pellets were implanted in mice during the effector phase of adoptive EAE. Disease scores were compared between treatment groups, and autoantigen-specific humoral and cellular responses were examined. RESULTS: Estriol treatment reduced the severity of EAE significantly compared with placebo treatment whereas progesterone treatment had no effect. Estriol doses that induced serum estriol levels that approximated estriol levels during late pregnancy were capable of ameliorating disease. Estriol-treated EAE mice had significantly higher levels of serum antibodies of the immunoglobulin (Ig) G1 isotype specific for the autoantigen myelin basic protein (MBP). Further, MBP-specific T-lymphocyte responses from estriol-treated EAE mice were characterized by significantly increased production of the Th2 cytokine interleukin 10 (IL-10). T lymphocytes were shown to be the primary source of IL-10 within antigen-stimulated splenocyte populations. CONCLUSIONS: Estriol as a hormone involved in immune changes during pregnancy may provide a basis for the novel therapeutic use of estriol for MS and other putative Th1-mediated autoimmune diseases that improve during late pregnancy.

Rate of pregnancy-related relapse in multiple sclerosis.

            (Confavreux, Hutchinson et al. 1998) Download

BACKGROUND AND METHODS: Multiple sclerosis often occurs in young women, and the effect of pregnancy on the disease is poorly understood. We studied 254 women with multiple sclerosis during 269 pregnancies in 12 European countries. The women were followed during their pregnancies and for up to 12 months after delivery to determine the rate of relapse per trimester and the score on the Kurtzke Expanded Disability Status Scale (range, 0 to 10, with higher scores indicating more severe disability). The relapse rate in each trimester was compared with the rate during the year before the pregnancy. The effects of epidural analgesia and breast-feeding on the frequency of relapse during the first three months post partum and the disability score at 12 months post partum were also determined. RESULTS: The mean (+/-SD) rate of relapse was 0.7+/-0.9 per woman per year in the year before pregnancy; it was 0.5+/-1.3 during the first trimester (P=0.03 for the comparison with the rate before pregnancy), 0.6+/-1.6 during the second trimester (P=0.17), and 0.2+/-1.0 during the third (P<0.001). The rate increased to 1.2+/-2.0 during the first three months post partum (P<0.001) and then returned to the prepregnancy rate. The mean Kurtzke disability score worsened by 0.7 point during 33 months of follow-up, with no apparent acceleration during the post-partum period. Neither breast-feeding nor epidural analgesia had an adverse effect on the rate of relapse or on the progression of disability in multiple sclerosis. CONCLUSIONS: In women with multiple sclerosis, the rate of relapse declines during pregnancy, especially in the third trimester, and increases during the first three months post partum before returning to the prepregnancy rate.

Pregnancy and Multiple Sclerosis

            (Damek and Shuster 1997) Download

In this review, we summarize the available information on the short- and long-term effects of pregnancy on the course of multiple sclerosis (MS). Published studies that used established criteria for the diagnosis of MS were given more weight than studies in which the criteria for diagnosis were unstated or unclear. Population-based studies were emphasized more than clinic-based studies, unless the clinic base was well defined and thought to be reasonably representative of the MS population in the geographic area. For completeness, small studies were also included but weighted accordingly in our overall conclusions. Methodologic limitations and biases inherent in the study methods are discussed. We conclude that patients with relapsing MS have an increased risk of relapse during the initial 6-month postpartum period. This increased risk does not seem to have a detrimental effect on the rate of developing sustained disability. In fact, a full-term pregnancy may increase the time interval to reaching a common disability endpoint-walking with the aid of a cane or crutch--or to having a secondarily progressive course. Evidence indicates that pregnancy may alter T-lymphocyte functions and cause clinically relevant consequences. The specific biochemical mechanisms responsible for these observations, however, remain undefined. Because of limitations of current knowledge, our conclusions are tentative at best. The data are most applicable to patients with relapsing-remitting MS in its early stages. MS is an unpredictable disease and is only one of many factors that patients must consider when a pregnancy is contemplated.

Estrogens attenuate and corticosterone exacerbates excitotoxicity, oxidative injury, and amyloid beta-peptide toxicity in hippocampal neurons

            (Goodman, Bruce et al. 1996) Download

Steroid hormones, particularly estrogens and glucocorticoids, may play roles in the pathogenesis of neurodegenerative disorders, but their mechanisms of action are not known. We report that estrogens protect cultured hippocampal neurons against glutamate toxicity, glucose deprivation, FeSO4 toxicity, and amyloid beta-peptide (A beta) toxicity. The toxicity of each insult was significantly attenuated in cultures pretreated for 2 h with 100 nM-10 microM 17 beta-estradiol, estriol, or progesterone. In contrast, corticosterone exacerbated neuronal injury induced by glutamate, FeSO4, and A beta. Several other steroids, including testosterone, aldosterone, and vitamin D, had no effect on neuronal vulnerability to the different insults. The protective actions of estrogens and progesterone were not blocked by actinomycin D or cycloheximide. Lipid peroxidation induced by FeSO4 and A beta was significantly attenuated in neurons and isolated membranes pretreated with estrogens and progesterone, suggesting that these steroids possess antioxidant activities. Estrogens and progesterone also attenuated A beta- and glutamate-induced elevation of intracellular free Ca2+ concentrations. We conclude that estrogens, progesterone, and corticosterone can directly affect neuronal vulnerability to excitotoxic, metabolic, and oxidative insults, suggesting roles for these steroids in several different neurodegenerative disorders.


References

Confavreux, C., M. Hutchinson, et al. (1998). "Rate of pregnancy-related relapse in multiple sclerosis. Pregnancy in Multiple Sclerosis Group." N Engl J Med 339(5): 285-91.

Damek, D. M. and E. A. Shuster (1997). "Pregnancy and multiple sclerosis." Mayo Clin Proc 72(10): 977-89.

Dubal, D. B., H. Zhu, et al. (2001). "Estrogen receptor alpha, not beta, is a critical link in estradiol-mediated protection against brain injury." Proc Natl Acad Sci U S A 98(4): 1952-7.

Foster, S. C., C. Daniels, et al. (2003). "Dysregulation of the hypothalamic-pituitary-gonadal axis in experimental autoimmune encephalomyelitis and multiple sclerosis." J Neuroimmunol 140(1-2): 78-87.

Garcia-Segura, L. M., I. Azcoitia, et al. (2001). "Neuroprotection by estradiol." Prog Neurobiol 63(1): 29-60.

Goodman, Y., A. J. Bruce, et al. (1996). "Estrogens attenuate and corticosterone exacerbates excitotoxicity, oxidative injury, and amyloid beta-peptide toxicity in hippocampal neurons." J Neurochem 66(5): 1836-44.

Kim, S., S. M. Liva, et al. (1999). "Estriol ameliorates autoimmune demyelinating disease: implications for multiple sclerosis." Neurology 52(6): 1230-8.

Liu, H. B., K. K. Loo, et al. (2003). "Estrogen receptor alpha mediates estrogen's immune protection in autoimmune disease." J Immunol 171(12): 6936-40.

Liva, S. M. and R. R. Voskuhl (2001). "Testosterone acts directly on CD4+ T lymphocytes to increase IL-10 production." J Immunol 167(4): 2060-7.

Sandstrom, N. J. and C. L. Williams (2001). "Memory retention is modulated by acute estradiol and progesterone replacement." Behav Neurosci 115(2): 384-93.

Sicotte, N. L., S. M. Liva, et al. (2002). "Treatment of multiple sclerosis with the pregnancy hormone estriol." Ann Neurol 52(4): 421-8.

Wise, P. M., D. B. Dubal, et al. (2001). "Minireview: neuroprotective effects of estrogen-new insights into mechanisms of action." Endocrinology 142(3): 969-73.