Biomarkers of Irritable Bowel Syndrome

Abstract

Traditionally, irritable bowel syndrome (IBS) has not been regarded as an organic disease, and the pathophysiology of IBS is heterogeneous. Currently, the diagnosis of IBS is based upon the Rome diagnostic criteria. The performance of these criteria is only modest in predicting IBS, and moreover their validation is lacking. Additionally, as functional symptoms are common in the general population, healthy controls or volunteers are difficult to define and there is currently no definition of "normal" in the Rome criteria. Due to the weaknesses of the current diagnostic criteria, patients and doctors expect new gold standard diagnostic tools. Various etiologic mechanisms result in potential biomarkers. The focus of this research has been to find non-invasive biomarkers from serum, breath gas, and fecal materials. Though biomarkers should be based on biological and pathogenic processes, most biomarkers for IBS have been developed to identify organic diseases and therefore eliminate IBS. To date, these types of biomarkers for IBS have been disappointing. The purposes of developing biomarkers include improvement of diagnosis, differentiation from other organic diseases, and discrimination of IBS subtypes. A true mechanistic biomarker would make it possible to rule in IBS, rather than to rule out other organic diseases. New serologic biomarkers for diarrhea-predominant IBS have been introduced based on the pathophysiologic findings from a rat model and validation in a large-scale clinical trial. Further investigations of abnormal organic findings from each subtype of IBS would enable the development of new, simple subtype-specific biomarkers.

Fecal Clostridiales distribution and short‐chain fatty acids reflect bowel habits in irritable bowel syndrome

“…By contrast, in the study of Ringel‐Kulka and colleagues (), SCFAs were found to discriminate IBS from healthy controls only when based on the subtype. Therefore, although they are recognized as biomarkers for IBS (Kim et al ., ), SCFAs require further study to elucidate their actual role in IBS.…”

“…IBS is conventionally classified into four subtypes according to bowel habits: IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), and IBS with alternating constipation and diarrhea (mixed IBS, IBS-M) as well as unsubtyped IBS (IBS-U) (Mearin et al, 2016). The diverse mechanisms underlying the pathophysiology of IBS subtypes remain unknown, and validated mechanistic biomarkers for the IBS subtypes are not available (Kim et al, 2017). IBS-subtype specific alterations of the intestinal microbiota have been reported (Malinen et al, 2005;Kassinen et al, 2007;Lyra et al, 2009;Carroll et al, 2010;Pozuelo et al, 2015;Tap et al, 2017).…”

The propionic acid and butyric acid in serum but not in feces are increased in patients with diarrhea-predominant irritable bowel syndrome

“…However, we found no significant differences with respect to the fecal propionic/butyric ratio and propionic acid-butyric acid in patients with IBS-D and HCs. Others also agreed that fecal SCFAs could be used as a biomarker for the discrimination of IBS from HCs [31]. A recent systematic review and meta-analysis demonstrated that fecal butyrate was increased in IBS-D patients in comparison to HCs, and fecal propionate and butyrate could be used as biomarkers for IBS diagnosis [32].…”

Assessment of the Quality and Content of Clinical Practice Guidelines on Irritable Bowel Syndrome Using the AGREE II Instrument

“…Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, associated with a range of symptoms including abdominal pain or bloating and altered bowel habits [1][2][3][4]. It affects around 10-15% of the population [5], women being more frequently affected with a two-to threefold increase [6].…”