Multiple functional therapeutic effects of the estrogen receptor β agonist indazole-Cl in a mouse model of multiple sclerosis

Abstract

Currently available immunomodulatory therapies do not stop the pathogenesis underlying multiple sclerosis (MS) and are only partially effective in preventing the onset of permanent disability in patients with MS. Identifying a drug that stimulates endogenous remyelination and/or minimizes axonal degeneration would reduce the rate and degree of disease progression. Here, the effects of the highly selective estrogen receptor (ER) β agonist indazole chloride (Ind-Cl) on functional remyelination in chronic experimental autoimmune encephalomyelitis (EAE) mice were investigated by assessing pathologic, functional, and behavioral consequences of both prophylactic and therapeutic (peak EAE) treatment with Ind-Cl. Peripheral cytokines from autoantigen-stimulated splenocytes were measured, and central nervous system infiltration by immune cells, axon health, and myelination were assessed by immunohistochemistry and electron microscopy. Therapeutic Ind-Cl improved clinical disease and rotorod performance and also decreased peripheral Th1 cytokines and reactive astrocytes, activated microglia, and T cells in brains of EAE mice. Increased callosal myelination and mature oligodendrocytes correlated with improved callosal conduction and refractoriness. Therapeutic Ind-Cl-induced remyelination was independent of its effects on the immune system, as Ind-Cl increased remyelination within the cuprizone diet-induced demyelinating model. We conclude that Ind-Cl is a refined pharmacologic agent capable of stimulating functionally relevant endogenous myelination, with important implications for progressive MS treatment.M ultiple sclerosis (MS) is an autoimmune, demyelinating, and neurodegenerative disease of the central nervous system (CNS) that affects 2-2.5 million people worldwide. Currently approved MS drugs reduce relapse rates but fail to reverse or prevent neurodegeneration and disability progression. Disease-modifying drugs capable of restoring neuronal function via axon remyelination (RM) represent a major unmet goal for MS therapeutics.Oligodendrocyte (OL) progenitor cells (OPCs) are responsible for remyelinating axons, make up at least 3% of all white matter cells, and are present in and around MS lesions; however, they remain largely quiescent in the adult CNS (1). Although endogenous RM can occur in patients with MS, as evidenced by shadow plaques, it is short-lived, incomplete, and relatively ineffective (2). Transition to progressive MS is characterized by increased axon loss, which correlates with RM failure (3). Hence, a treatment that stimulates endogenous OPCs to differentiate and remyelinate axons would reduce axon degeneration and restore neuronal function.Experimental autoimmune encephalomyelitis (EAE) affords researchers an in-depth, mechanistic understanding of immunemediated, demyelinating neurodegeneration and anti-inflammatory effects of currently approved MS drugs. Our recent work has demonstrated promising neuroprotective effects of the estrogen receptor (ER) β agonist 2,3-bis(4-hydroxyphenyl)propionitrile...

Consistent induction of chronic experimental autoimmune encephalomyelitis in C57BL/6 mice for the longitudinal study of pathology and repair

“…Additionally, mouse weights will fluctuate during the disease course and can serve as an additional indicator of disease severity. Generally, EAE mice lose ∼15–20% of their body weight just prior to disease onset, reach a minimum weight a few days before peak clinical severity, and continue to regain weight throughout the experiment (Moore et al, 2014b). Mice which fail to regain weight should be closely monitored to ensure proper nutrition and hydration.…”

ERβ-Dependent Direct Suppression of Human and Murine Th17 Cells and Treatment of Established Central Nervous System Autoimmunity by a Neurosteroid

“…DHEA, which activates ERa in addition to ERb (30), may also exert several side effects (45,46). For this, the focus of several studies has turned to synthetic ligands that selectively activate ERb and are thus devoid of undesired carcinogenic effects (47). A previous study highlights the use of the prodrug DHED that is metabolized to estradiol selectively in the brain and could have valuable therapeutic effects on human diseases associated with estrogen-mediated neuroprotection (48), such as multiple sclerosis.…”

ERβ in CD4+ T Cells Is Crucial for Ligand-Mediated Suppression of Central Nervous System Autoimmunity

“…The immunomodulatory and neuroprotective effects of IndazoleCl in EAE have been described previously (9,34). However, in these studies, the direct effects of Indazole-Cl on specific Th cell subsets, such as Th17, were not addressed.…”