Gut microbiota profiles and the role of anti-CdtB and anti-vinculin antibodies in patients with functional gastrointestinal disorders (FGID).

Background Distinct fecal microbiota profiles are reported to be associated with various subtypes of IBS. Circulating antibodies to cytolethal-distending-toxin B (CdtB) and vinculin are proposed as biomarkers to identify post-infectious IBS. The aim of our study was to analyze serum levels of anti-CdtB and anti-vinculin antibodies in patients with different Functional Gastrointestinal Disorders (FGID) and their correlation with the composition of fecal microbiome. Methods The study cohort comprised 65 prospectively recruited individuals: 15 with Diarrhea-type-IBS (IBS-D), 13 with Constipation-type-IBS (IBS-C), 15 with functional dyspepsia (FD) and 22 healthy controls. FGID subgroups were defined according to Rome III criteria. Serum levels of anti-CdtB and anti-vinculin antibodies were measured by ELISA. Fecal microbiome composition analysis and assessment of dysbiosis were performed by GA-map®-Dysbiosis Test. Results Positivity rate either for anti-CdtB or anti-vinculin antibodies was higher in the IBS-C group (76.9%) compared to IBS-D (40.0%), FD (60%) and healthy (63.6%) groups. Dysbiosis was more frequent in subjects positive for anti-CdtB antibodies and in IBS-C patients, who showed an increased amount of opportunistic/pro-inflammatory bacteria and reduced gut protective bacteria. IBS-C patients showed a high inter-individual variation of bacterial communities compared to other FGID subgroups and healthy individuals, whereas microbial profiles of patients with IBS-D and FD were overlapping with those of healthy controls. No bacteria markers showed significant differences between FGID subgroups and healthy controls. Conclusion Neither anti-CdtB/anti-vinculin antibodies nor fecal microbial profiles allowed to discriminate between specific FGID subgroups. Dysbiosis was more frequent in patients presenting with anti-CdtB antibodies and in IBS-C patients.