phytoestrogens and Autoimmune-Diseases

Multiple sclerosis (MS) is a chronic and progressive autoimmune disease of the central nervous system (CNS), with both genetic and environmental factors contributing to the pathobiology of the disease. Although HLA genes have emerged as the strongest genetic factor linked to MS, consensus on the environmental risk factors is lacking. Recently, the gut microbiota has garnered increasing attention as a potential environmental factor in MS, as mounting evidence suggests that individuals with MS exhibit microbial dysbiosis (changes in the gut microbiome). Thus, there has been a strong emphasis on understanding the role of the gut microbiome in the pathobiology of MS, specifically, factors regulating the gut microbiota and the mechanism(s) through which gut microbes may contribute to MS. Among all factors, diet has emerged to have the strongest influence on the composition and function of gut microbiota. As MS patients lack gut bacteria capable of metabolizing dietary phytoestrogen, we will specifically discuss the role of a phytoestrogen diet and phytoestrogen metabolizing gut bacteria in the pathobiology of MS. A better understanding of these mechanisms will help to harness the enormous potential of the gut microbiota as potential therapeutics to treat MS and other autoimmune diseases.

Topics: Autoimmune Diseases; Bacteria; Diet; Dysbiosis; Humans; Microbiota; Multiple Sclerosis; Phytoestrogens

The prevalence of autoimmune diseases has significantly increased over the recent years. It has been proposed that this epidemiological evidence could be in part attributable to environmental estrogens, compounds that display estrogen-like activity and are ubiquitously present in the environment. Environmental estrogens can be found in a wide variety of foods: phytoestrogens occur in plants such as clover and soy, while mycoestrogens are food contaminants produced by fungi. Meat, eggs and dairy products from animals given exogenous hormones contain relatively high concentration of estrogens. Among xenoestrogens, industrial estrogens are synthetic chemicals produced for specific purposes (pesticides, plastics, surfactants and detergents) while metalloestrogens are found in heavy metals. Estrogens can be also administered through medications (contraceptive pill, hormone replacement therapy, genistein, cimetidine, creams). There is a considerable burden of evidence in vitro and in animal models that these compounds may exert immunotoxic effects. However, to date there is no convincing data that exposure to environmental estrogens can be regarded as a risk for human health. In particular, there is no consensus whether prolonged exposure to relatively low concentrations of different estrogenic chemicals can affect the human immune system and induce clinically evident diseases in real-life scenario. Moreover, the effects on human health of the synergistic interactions between natural, medical, dietary and environmental estrogens have not been fully elucidated yet. Here we provide an extensive review of the in vivo and in vitro effects of environmental estrogens on the immune system, focusing on the evidences of association between exposure and autoimmune disorders.

Topics: Animals; Autoimmune Diseases; Autoimmunity; Environmental Exposure; Environmental Pollutants; Estrogens; Estrogens, Non-Steroidal; Food Contamination; Humans; Phytoestrogens