Dietary Phytoestrogens as Risk Factors for Systemic Lupus Erythematosus (ISOLED)

The study aims at determining if dietary phytoestrogens can be risk factors for Systemic Lupus Erythematosus (SLE). Dietary enquiry and phytoestrogens measurements will be performed in blood and urine of patients with SLE in an active phase of the disease, in patient with other autoimmune diseases and in healthy volunteers. Subjects will be premenopausal women and when possible at a define stage of the menstrual cycle. Free blood estradiol will be assayed as a confounding risk factor.

SLE is a disease occurring in 90% of the cases in pre-menopausal women. The causing factors are largely unknown even though genetic and environmental factors have already been identified. Estrogens, on one side, have been shown to negatively influence the incidence and severity of the disease while testosterone and progesterone on the other side are thought to be protective. Endocrine disruptors can potentially influence the occurrence and severity of the disease. Among these disruptors, soy isoflavones which are ubiquitous in modern processed food are known to be estrogenic and anti-androgenic. Their depleting effect on luteinizing hormone (LH) secretion can also lead to progesterone plasma level impairments. For these reasons, estrogenic isoflavones, appear as potential environmental risk factors for SLE and its flares. Although some data exist in transgenic rodent, there is actually no clinical data in young women. The study is an observational, monocentric, preliminary study aiming at determining if estrogenic isoflavones can be risk factors for SLE. No treatment is planned. The intervention will be the collection of extra blood and urine samples on SLE subjects and on autoimmune and healthy counterparts. Consumers are unintentionally exposed to estrogenic isoflavones through their diet. A dietary habit enquiry and a 48h dietary recall (based on pharmacokinetics of soy-isoflavones) will be proposed to the included subjects. Urine and blood samples collected during a clinical visit performed 7 days after the onset of previous menses will be analyzed for soy isoflavones, metabolites and for enterolactone both free and conjugated. Free estradiol will be assayed as a potential confounding risk factor.

Inclusion Criteria: Group : Systemic Lupus Erythematosus : Premenopausal women over 18 with acute LEAD flare having given informed consent and being covered by social insurance. Group : Autoimmune diseases : Premenopausal women of matching age with other autoimmune disease, having given informed consent and being covered by social insurance. Healthy controls : Premenopausal women over 18, having given informed consent, and being covered by social insurance. Exclusion Criteria: Group Systemic Lupus Erythematosus and group autoimmune diseases Human Immunodeficiency virus (HIV), hepatitis C virus (HCV) or hepatitis C virus (HBV) sero-positivity; pregnant or lactating women; menopausal women; patient in remission of quiescent phase of her pathology; Healthy controls : HIV, HCV or HBV sero-positivity; pregnant or lactating women; menopausal women.