ORIGINAL ARTICLE Ratio of Circulating Estrogen Receptors Beta and Alpha (ERb/ERa) Indicates Endoscopic Activity in Patients with Crohn’s Disease Pablo M. Linares 1 • Alicia Algaba 2 • Ana Urzainqui 3 • Mercedes Guijarro-Rojas 4 • Rafael Gonza ´lez-Tajuelo 3 • Jesu ´s Garrido 5 • Marı ´a Chaparro 1 • Javier P. Gisbert 1 • Fernando Bermejo 2 • Iva ´n Guerra 2 • Vı ´ctor Castellano 6 • Marı ´a-Encarnacio ´n Ferna ´ndez-Contreras 1,7 Received: 12 January 2017 / Accepted: 7 August 2017 Ó Springer Science+Business Media, LLC 2017 Abstract Background Data supporting a role of female hormones and/or their receptors in inflammatory bowel disease (IBD) are increasing, but most of them are derived from animal models. Estrogen receptors alpha (ERa) and beta (ERb) participate in immune and inflammatory response, among a variety of biological processes. Their effects are antago- nistic, and the net action of estrogens may depend on their relative proportions. Aim To determine the possible association between the balance of circulating ERb and ERa (ERb/ERa) and IBD risk and activity. Methods Serum samples from 145 patients with IBD (79 Crohn’s disease [CD] and 66 ulcerative colitis [UC]) and 39 controls were retrospectively studied. Circulating ERa and ERb were measured by ELISA. Disease activities were assessed by clinical and endoscopic indices specific for CD and UC. & Marı ´a-Encarnacio ´n Ferna ´ndez-Contreras mefdezcontreras@hotmail.com Pablo M. Linares pablus@hotmail.com Alicia Algaba alicia_algaba@hotmail.com Ana Urzainqui ana.urzainqui@salud.madrid.org Mercedes Guijarro-Rojas merguiro@gmail.com Rafael Gonza ´lez-Tajuelo rafagonzaleztj@gmail.com Jesu ´s Garrido jesgarri@gmail.com Marı ´a Chaparro mariachs2005@gmail.com Javier P. Gisbert javier.p.gisbert@gmail.com Fernando Bermejo fbermejos1@gmail.com Iva ´n Guerra ivangm79@gmail.com Vı ´ctor Castellano vmcastellano@hotmail.com 1 Department of Gastroenterology, Hospital Universitario de La Princesa, Instituto de Investigacio ´n Sanitaria Princesa (IIS-IP) and Centro de Investigacio ´n Biome ´dica en Red de Enfermedades Hepa ´ticas y Digestivas (CIBEREHD), C/ Diego de Leo ´n 62, 28006 Madrid, Spain 2 Department of Gastroenterology, Hospital Universitario de Fuenlabrada, C/ Camino del Molino 2, 28942 Fuenlabrada-Madrid, Spain 3 Department of Immunology, Hospital Universitario de la Princesa, IIS-IP, C/ Diego de Leo ´n 62, 28006 Madrid, Spain 4 Department of Pathology, Hospital Universitario de la Princesa, IIS-IP, C/ Diego de Leo ´n 62, 28006 Madrid, Spain 5 Department of Social Psychology and Methodology, School of Psychology, Universidad Auto ´noma de Madrid (UAM), C/ Ivan Pavlov 6. Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain 6 Department of Pathology, Hospital Universitario de Fuenlabrada, C/ Camino del Molino 2, 28942 Fuenlabrada-Madrid, Spain 7 Departments of Anatomy I and Immunology, School of Medicine, Universidad Alfonso X El Sabio (UAX), Avda. de la Universidad 1, 28691 Villanueva de la Can ˜ada, Madrid, Spain 123 Dig Dis Sci DOI 10.1007/s10620-017-4717-5