Preliminary reportGenistein down-modulates pro-inflammatory cytokines and reverses clinical signs of experimental autoimmune encephalomyelitis
Introduction
MS is a chronic inflammatory disorder of the CNS with unknown etiology affecting approximately 2.5 million people worldwide [1], [2]. A complex predisposing genetic trait and an inciting environmental insult such as infections agents appear to be important in triggering the disease, comprising as hallmarks inflammation, demyelination and axonal damage [1], [3]. Cytokines such as TNF-α, IFN-γ, IL-17 and IL-12, and to some extent chemokines play a pivotal role in the establishment and maintenance of autoimmune disorders, acting in highly complex networks, and often exert overlapping and in part redundant functions by different cell types. Also, pro-inflammatory cytokines are thought to play a role in the pathogenesis of MS [4], [5]. Due to its similarity to MS, EAE has been used as an animal model for proof of concept studies of MS therapy.
Both clinical and experimental evidence suggests that sex hormones in males and females are significant factors responsible for the sexual dimorphism in the immune response. The best-studied regulatory hormone, estrogen, is protective against the induction of EAE, demonstrating several immunosuppressive mechanisms. Phytoestrogens are a group of biologically active plant substances with a chemical structure similar to estrogen, exerting estrogenic and anti-estrogenic effects [6]. Previous data suggest that the consumption of phytoestrogens leads to protective effects against menopausal symptoms and a variety of disorders, including diabetes and cancer [7], [8]. Isoflavones make up the most common form of phytoestrogens and are found in a variety of plants, especially in soy [9]. Genistein is the major bioactive isoflavone, demonstrating a variety of properties such as induction of apoptosis in cancer cells and antioxidant effects [10], [11]. However, little has been elucidated with regard to its potential in autoimmune diseases caused by T cell activation.
IFN-β has been approved for treatment of relapsing–remitting-MS and is currently the agent that is most broadly used as an immunomodulatory and suppressive treatment. It reduces exacerbation by only 30% and has a modest impact on disease progression. Indeed, it is a clear step forward in MS therapy, but the frequency of subcutaneous injections of IFN-β, the flu-like symptoms that occur at the beginning of therapy, the modest activity required of patients, and the treatment failures are all reasons to search for better agents [5]. In this report, we sought to determine the clinical and biological effects of isoflavone genistein on the myelin MOG-induced EAE model.
Section snippets
Animals
Female C57Bl/6 mice 8–12 weeks old were obtained from the Animal Care Facilities of the Federal University of Juiz de Fora (UFJF) and housed in microisolator cages in the animal facility at the Laboratory of Immunology. All procedures were in accordance with the principles of the Brazilian Code for the Use of Laboratory Animals. This project was approved by the Ethics Committee on the use of laboratory animals from UFJF.
EAE induction
Groups of 3–6 animals were immunized or not subcutaneously (s.c.) at both
Treatment with genistein ameliorates the EAE clinical course
The initial clinical expression of the axonal damage in an EAE model is represented by well-defined signs such as weight loss, tail paralysis and hind-limb weakness [14]. In this work, we investigated whether genistein would be effective in the treatment of EAE induced in C57Bl/6 mice. These animals were immunized with MOG35–55 peptide in adjuvant, and a group was treated daily with genistein 3 days after the beginning of the clinical signs (14 dpi), when the disease was already established.
Discussion
MS is still considered a CD4+ Th1-mediated autoimmune disease, which has socioeconomic importance second only to trauma in young adults [5]. Although a number of immunomodulatory and immunosuppressive agents have been applied to MS treatment, better defined therapeutic strategies are required. Flavonoids and phytoestrogens have been tested in the EAE murine model, demonstrating that these compounds may have beneficial properties [15], [16], [17]. Due to genistein being the major bioactive
Acknowledgments
This work was supported by grants from CAPES, CNPq and FAPEMIG. Language assistance was provided by Daniel Stockdell.
References (36)
- et al.
Genetics of multiple sclerosis
Lancet Neurol
(2004) - et al.
Beneficial role of dietary phytoestrogens in obesity and diabetes
Am J Clin Nutr
(2002) - et al.
Genistein-induced apoptosis and autophagocytosis in ovarian cancer cells
Gynecol Oncol.
(2007) - et al.
Interferon-gamma induces microglial-activation-induced cell death: a hypothetical mechanism of relapse and remission in multiple sclerosis
Neurobiol Dis
(2006) - et al.
IL-12/IFN-gamma/NO axis plays critical role in development of Th1-mediated experimental autoimmune encephalomyelitis
Mol Immunol
(2008) - et al.
Cytokines in the induction and resolution of experimental autoimmune encephalomyelitis
Cytokine
(2005) - et al.
IL-10, a key effector regulatory cytokine in experimental autoimmune encephalomyelitis
J Autoimmun
(2003) - et al.
Inflammation and therapeutic vaccination in CNS diseases
Nature
(2002) - et al.
Transcriptional analysis of targets in multiple sclerosis
Nat Rev Immunol
(2003) - et al.
Cytokines as intrinsic and exogenous regulators of pathogenesis in experimental autoimmune encephalomyelitis
Res Immunol
(1998)