A team of VHIR researchers, led by Dr. Javier Santos and Dr. Maria Vicario, has discovered that people with diarrhea-predominant irritable bowel syndrome (IBS-D) present increased immune activity in their small intestine as compared to healthy persons. The results of the study have been recently published in the journal "http://gut.bmj.com/content/early/2014/09/10/gutjnl-2013-306236.abstract?sid=2ec33269-718a-4385-a186-72d300b8db98" Gut and highlighted in the November issue of "http://www.nature.com/nrgastro/journal/vaop/ncurrent/full/nrgastro.2014.169.html" Nature Reviews, Gastroenterology and Hepatology."Surprisingly, we have detected that patients with the disease have a higher number of antibody-producing cells in their jejunum than healthy subjects" explains Dr. Vicario. The majority of these antibodies are IgG immunoglobulins (Ig), which are more efficient than other types of Ig and are produced upon stimulation of B cells by specific antigens.By performing gene expression analysis, the research team revealed previously undescribed alterations at the molecular and cellular level that are associated to the clinical manifestations of the disease. "We found that the more activated the defenses in the intestine of these patients, the more severe are the symptoms", points out Dr. Vicario. The main symptoms of IBS are lower abdominal pain and modifications in stool frequency and consistency.To date, diagnosis of SII is established solely on the basis of clinical criteria and exclusion of other diseases. No reliable biomarkers exist, reason for which Dr. Santos underlines that "the results obtained in this study pave the way to the design of a test, based on the detection of immune activity in the intestine, to facilitate IBS diagnosis". The increased immune activation is detected in the small intestine but not in the blood of these patients, which indicates that it is a local event and explains why routine clinical analysis in these patients are often absolutely normal.IBS is a chronic and debilitating disease that affects approximately 15% of the population in developed countries. The chronicity of the disease, together with the lack of efficient therapies, significantly decreases the patient's quality of life and represents a considerable health-care cost for society.