: Among the gut microbiota’s newly explored roles in human biology is the ability to modify the chemical structures of foreign compounds (xenobiotics). A growing body of evidence has now provided sufficient acumen on the role of the gut microbiota on xenobiotic metabolism, which could have an intense impact on the therapy for various diseases in the future. Gut microbial xenobiotic metabolites have altered bioavailability, bioactivity and toxicity and can intervene with the actions of human xenobiotic-metabolizing enzymes to affect the destiny of other ingested molecules. These modifications are diverse and could lead to physiologically important consequences.: In the current manuscript we aim to review the data currently available on how the gut microbiota directly modifies drugs, dietary compounds, chemicals, pollutants, pesticides and herbal supplements.

Background: Patients with irritable bowel syndrome (IBS) usually suffer from nonspecific and overlapping signs that hamper the diagnostic process. In line with this, biomarkers specific for IBS could be of great benefit for diagnosing and managing patients. In IBS, the need is for apparent distinguishing features linked to the disease that improve diagnosis, differentiate from other organic diseases, and discriminate between IBS subtypes. Summary: Some biomarkers are associated with a possible pathophysiologic mechanism of IBS; others are used for differentiating IBS from non-IBS patients. Implementation of IBS biomarkers in everyday clinical practice is critical for early diagnosis and treatment. However, our knowledge about their efficient use is still scarce. Key Messages: This review discusses the biomarkers implemented for IBS diagnosis and management, such as blood (serum), fecal, immunological, related to the microbiome, microRNAs, and some promising novel biomarkers associated with imaging and psychological features of the disease. We focus on the most commonly studied and validated biomarkers and their biological rationale, diagnostic, and clinical value.

Aims: We aimed to evaluate the prevalence of irritable bowel syndrome (IBS), functional dyspepsia (FD), and their overlap syndrome (OS) in the Bulgarian population and to assess the risk factors associated with these disorders. Methods: We sent an internet-based survey to Bulgarian adults. The survey collected data on socio- demographic, behavioral and lifestyle characteristics, and diagnostic questions following the Rome IV criteria to assess IBS, FD and their overlap occurrence. Results: Data was collected from 1,896 individuals (mean age = 35.5 years, 18-65, SD=11.7), 73.1% females. The prevalence of IBS was 20% (14% were with predominant constipation, 32% with predominant diarrhea, 52% had IBS with mixed bowel habits, and 2% unclassified IBS). Gender (p=0.005), age (p<0.001), marital status (p=0.009), occupation (p=0.001), alcohol consumption (p=0.013), sexual problems (p<0.001), FD (p<0.001), and milk intolerance (p<0.001) were significantly associated with IBS. Females (p=0.032; OR: 1.50), patients with FD (p<0.001; OR: 104.98), sexual problems (p= 0.001; ОR: 1.55 ), and milk intolerance (p<0.001; OR: 2.22) are at a higher risk of having IBS. The prevalence of FD was 12.7% (39% had postprandial distress syndrome, 33% epigastric pain syndrome, and 28% had the overlapping variant). Patients with IBS (p<0.001; OR: 127.88) and milk intolerance (p<0.001) were significantly associated with FD prevalence. The prevalence of OS was 11.7%. Gender (p=0.013), milk intolerance (p<0.001, OR: 1.65), urinary (p=0.035) and sexual problems (p<0.001, ОR: 1.80) were associated with OS prevalence. Conclusion: This is the first study to estimate the prevalence of IBS, FD, and their OS and assess the behavioral and demographic risk factors associated with these disorders in the Bulgarian population. Our results are valuable in filling in the epidemiological data gap regarding IBS, FD, and OS in Eastern Europe.

Aim: In the current study we aimed to evaluate the role of trefoil factor 3 (TFF3) as a marker for complete mucosal healing (MH) in patients with ulcerative colitis (UC). Methods: We enrolled 116 consecutive UC patients. Trefoil factor 3 levels were measured by ELISA and were compared to the clinical activity, assessed by Lichtiger Index, fecal calprotectin (FCP) and C-reactive protein (CRP) levels. Colonoscopy was performed in all the patients and the findings were graded according to Mayo endoscopic score (EMS) and UC endoscopic index of severity (UCEIS). Results: Trefoil factor 3 levels were significantly correlated with Lichtiger Index (r=0.736, p<0.001), EMS (r=0.811, p<0.001), UCEIS (r=0.820, p<0.001), FCP (r=0.696, p<0.001) and CRP (r=0.405, p<0.001). The TFF3 cut-off level of 6.74 ng/ml indicated complete MH (EMS=0; UCEIS=0) with a sensitivity and specificity of 0.879 and 0.869, respectively (area under the curve, AUC 0.927; 95% confidence interval, 0.877–0.976). The DeLong’s test revealed no significant difference between the AUC of TFF3+CRP and the AUC of FCP (Z=1.717, p=0.086), AUC of TFF3+FCP (Z=1.908, p=0.056), and AUC of TFF3+CRP+FCPP (Z=1.915, p=0.056). However, the AUC of TFF3+CRP showed significant difference compared with the AUC of TFF3 (Z=2.210, p=0.027) and the AUC of CRP (Z=3.145, p=0.002) for predicting complete MH. Conclusions: Trefoil factor 3 levels correlated significantly with clinical activity, endoscopic indices, CRP and FCP in our patients. TFF3 is a highly predictive marker of complete MH independently and in combination with CRP in patients with UC.