Integration of stool microbiota, proteome and amino acid profiles to discriminate patients with adenomas and colorectal cancer.

BACKGROUND: Screening for colorectal cancer (CRC) reduces its mortality but has limited sensitivity and specificity. Aims We aimed to explore potential biomarker panels for CRC and adenoma detection and to gain insight into the interaction between gut microbiota and human metabolism in the presence of these lesions. METHODS: This multicenter case-control cohort was performed between February 2016 and November 2019. Consecutive patients ≥18 years with a scheduled colonoscopy were asked to participate and divided into three age, gender, body-mass index and smoking status-matched subgroups: CRC (n = 12), adenomas (n = 21) and controls (n = 20). Participants collected fecal samples prior to bowel preparation on which proteome (LC-MS/MS), microbiota (16S rRNA profiling) and amino acid (HPLC) composition were assessed. Best predictive markers were combined to create diagnostic biomarker panels. Pearson correlation-based analysis on selected markers was performed to create networks of all platforms. RESULTS: Combining omics platforms provided new panels which outperformed hemoglobin in this cohort, currently used for screening (AUC 0.98, 0.95 and 0.87 for CRC vs controls, adenoma vs controls and CRC vs adenoma, respectively). Integration of data sets revealed markers associated with increased blood excretion, stress- and inflammatory responses and pointed toward downregulation of epithelial integrity. CONCLUSIONS: Integrating fecal microbiota, proteome and amino acids platforms provides for new biomarker panels that may improve noninvasive screening for adenomas and CRC, and may subsequently lead to lower incidence and mortality of colon cancer.

The potential of fecal microbiota and amino acids to detect and monitor patients with adenoma.

The risk of recurrent dysplastic colonic lesions is increased following polypectomy. Yield of endoscopic surveillance after adenoma removal is low, while interval colorectal cancers occur. To longitudinally assess the dynamics of fecal microbiota and amino acids in the presence of adenomatous lesions and after their endoscopic removal. In this longitudinal case-control study, patients collected fecal samples prior to bowel preparation before scheduled colonoscopy and 3 months after this intervention. Based on colonoscopy outcomes, patients with advanced adenomas and nonadvanced adenomas (0.5-1.0 cm) who underwent polypectomy during endoscopy (n = 19) were strictly matched on age, body-mass index, and smoking habits to controls without endoscopic abnormalities (n = 19). Microbial taxa were measured by 16S RNA sequencing, and amino acids (AA) were measured by high-performance liquid chromatography (HPLC). Adenoma patients were discriminated from controls based on AA and microbial composition. Levels of proline (p = .001), ornithine (p = .02) and serine (p = .02) were increased in adenoma patients compared to controls but decreased to resemble those of controls after adenoma removal. These AAs were combined as a potential adenoma-specific panel (AUC 0.79(0.64-0.94)). For bacterial taxa, differences between patients with adenomas and controls were found (Bifidobacterium spp.↓, Anaerostipes spp.↓, Butyricimonas spp.↑, Faecalitalea spp.↑ and Catenibacterium spp.↑), but no alterations in relative abundance were observed after polypectomy. Furthermore, Faecalitalea spp. and Butyricimonas spp. were significantly correlated with adenoma-specific amino acids. We selected an amino acid panel specifically increased in the presence of adenomas and a microbial signature present in adenoma patients, irrespective of polypectomy. Upon validation, these panels may improve the effectiveness of the surveillance program by detection of high-risk individuals and determination of surveillance endoscopy timing, leading to less unnecessary endoscopies and less interval cancer.

The influence of lifestyle factors on fecal volatile organic compound composition as measured by an electronic nose.

INTRODUCTION: Fecal volatile organic compounds (VOCs) are gaseous metabolic products which are increasingly considered potential non-invasive biomarkers for the detection of various (gastrointestinal) diseases. The influence of lifestyle factors on fecal VOC patterns remains unexplored but is of importance prior to implementation of VOC analysis as a diagnostic tool. The aim of this study was to investigate the effects of age, gender, body mass index, smoking status, dietary preferences, medication use and co-morbidity on fecal VOC patterns. METHODS: For this study, fecal samples of patients undergoing a colonoscopy were collected prior to endoscopy. All participants completed a questionnaire on lifestyle factors, co-morbidity and medication use. Patients without colonic abnormalities were included in this study. Fecal VOC patterns were analyzed by means of an electronic nose (eNose) device (Cyranose® 320). RESULTS: From the 1039 participants willing to participate in the initial study, 211 were eligible as controls. All unique lifestyle variables investigated in this study affected the fecal VOC composition. The strongest influences were caused by low BMI, a vegetarian diet and an active smoking status, whereas the least influence was found for the variables gender, age > 55 years and previous smokers. DISCUSSION: Age, gender, BMI, smoking habits, dietary preferences, co-morbidity and medication use all have unique effects on fecal VOC composition. Future studies should carefully consider this influence on VOC outcome when defining VOC signatures as biomarker for diagnostic purposes.