Faculty Bibliography

BACKGROUND: An accurate system for tracking of colonoscopy quality and surveillance intervals could improve the effectiveness and cost-effectiveness of colorectal cancer (CRC) screening and surveillance. The purpose of this study was to create and test such a system across multiple institutions utilizing natural language processing (NLP). METHODS: From 42,569 colonoscopies with pathology records from 13 centers, we randomly sampled 750 paired reports. We trained (n=250) and tested (n=500) an NLP-based program with 19 measurements that encompass colonoscopy quality measures and surveillance interval determination, using blinded, paired, annotated expert manual review as the reference standard. The remaining 41,819 nonannotated documents were processed through the NLP system without manual review to assess performance consistency. The primary outcome was system accuracy across the 19 measures. RESULTS: A total of 176 (23.5%) documents with 252 (1.8%) discrepant content points resulted from paired annotation. Error rate within the 500 test documents was 31.2% for NLP and 25.4% for the paired annotators (P=0.001). At the content point level within the test set, the error rate was 3.5% for NLP and 1.9% for the paired annotators (P=0.04). When eight vaguely worded documents were removed, 125 of 492 (25.4%) were incorrect by NLP and 104 of 492 (21.1%) by the initial annotator (P=0.07). Rates of pathologic findings calculated from NLP were similar to those calculated by annotation for the majority of measurements. Test set accuracy was 99.6% for CRC, 95% for advanced adenoma, 94.6% for nonadvanced adenoma, 99.8% for advanced sessile serrated polyps, 99.2% for nonadvanced sessile serrated polyps, 96.8% for large hyperplastic polyps, and 96.0% for small hyperplastic polyps. Lesion location showed high accuracy (87.0-99.8%). Accuracy for number of adenomas was 92%. CONCLUSIONS: NLP can accurately report adenoma detection rate and the components for determining guideline-adherent colonoscopy surveillance intervals across multiple sites that utilize different methods for reporting colonoscopy findings.

Abstract The mucosal microbiota lives in close proximity with the intestinal epithelium and may interact more directly with the host immune system than the luminal/fecal bacteria. The availability of nutrients in the mucus layer of the epithelium is also very different from the gut lumen environment. Inferred metagenomic analysis for microbial function of the mucosal microbiota is possible by PICRUSt. We recently found that by using this approach, actively inflamed tissue of ulcerative colitis (UC) patients have mucosal communities enriched for genes involved in lipid and amino acid metabolism, and reduced for carbohydrate and nucleotide metabolism. Here, we find that the same bacterial taxa (e.g. Acinetobacter) and predicted microbial pathways enriched in actively inflamed colitis tissue are also enriched in the mucosa of subjects undergoing routine screening colonoscopies, when compared with paired samples of luminal/fecal bacteria. These results suggest that the mucosa of healthy individuals may be a reservoir of aerotolerant microbial communities expanded during colitis.

Acquisition of the intestinal microbiota begins at birth, and a stable microbial community develops from a succession of key organisms. Disruption of the microbiota during maturation by low-dose antibiotic exposure can alter host metabolism and adiposity. We now show that low-dose penicillin (LDP), delivered from birth, induces metabolic alterations and affects ileal expression of genes involved in immunity. LDP that is limited to early life transiently perturbs the microbiota, which is sufficient to induce sustained effects on body composition, indicating that microbiota interactions in infancy may be critical determinants of long-term host metabolic effects. In addition, LDP enhances the effect of high-fat diet induced obesity. The growth promotion phenotype is transferrable to germ-free hosts by LDP-selected microbiota, showing that the altered microbiota, not antibiotics per se, play a causal role. These studies characterize important variables in early-life microbe-host metabolic interaction and identify several taxa consistently linked with metabolic alterations. PAPERCLIP:

Soil-transmitted helminths colonize more than 1.5 billion people worldwide, yet little is known about how they interact with bacterial communities in the gut microbiota. Differences in the gut microbiota between individuals living in developed and developing countries may be partly due to the presence of helminths, since they predominantly infect individuals from developing countries, such as the indigenous communities in Malaysia we examine in this work. We compared the composition and diversity of bacterial communities from the fecal microbiota of 51 people from two villages in Malaysia, of which 36 (70.6%) were infected by helminths. The 16S rRNA V4 region was sequenced at an average of nineteen thousand sequences per samples. Helminth-colonized individuals had greater species richness and number of observed OTUs with enrichment of Paraprevotellaceae, especially with Trichuris infection. We developed a new approach of combining centered log-ratio (clr) transformation for OTU relative abundances with sparse Partial Least Squares Discriminant Analysis (sPLS-DA) to enable more robust predictions of OTU interrelationships. These results suggest that helminths may have an impact on the diversity, bacterial community structure and function of the gut microbiota.

BACKGROUND: Inflammation during inflammatory bowel disease may alter nutrient availability to adherent mucosal bacteria and impact their metabolic function. Microbial metabolites may regulate intestinal CD4 T-cell homeostasis. We investigated the relationship between inflammation and microbial function by inferred metagenomics of the mucosal microbiota from colonic pinch biopsies of patients with inflammatory bowel disease. METHODS: Paired pinch biopsy samples of known inflammation states were analyzed from ulcerative colitis (UC) (23), Crohn's disease (CD) (21), and control (24) subjects by 16S ribosomal sequencing, histopathologic assessment, and flow cytometry. PICRUSt was used to generate metagenomic data and derive relative Kyoto Encyclopedia of Genes and Genomes Pathway abundance information. Leukocytes were isolated from paired biopsy samples and analyzed by multicolor flow cytometry. Active inflammation was defined by neutrophil infiltration into the epithelium. RESULTS: Carriage of metabolic pathways in the mucosal microbiota was relatively stable among patients with inflammatory bowel disease, despite large variations in individual bacterial community structures. However, microbial function was significantly altered in inflamed tissue of UC patients, with a reduction in carbohydrate and nucleotide metabolism in favor of increased lipid and amino acid metabolism. These differences were not observed in samples from CD patients. In CD, microbial lipid, carbohydrate, and amino acid metabolism tightly correlated with the frequency of CD4Foxp3 Tregs, whereas in UC, these pathways correlated with the frequency of CD4IL-22 (TH22) cells. CONCLUSIONS: Metabolic pathways of the mucosal microbiota in CD do not vary as much as UC with inflammation state, indicating a more systemic perturbation of host-bacteria interactions in CD compared with more localized dysfunction in UC.

T helper type (Th17) cytokines such as interleukin (IL)-17A and IL-22 are important in maintaining mucosal barrier function and may be important in the pathogenesis of inflammatory bowel diseases (IBDs). Here, we analyzed cells from the colon of IBD patients and show that Crohn's disease (CD) patients had significantly elevated numbers of IL-17+, CD4+ cells compared with healthy controls and ulcerative colitis (UC) patients, but these numbers did not vary based on the inflammatory status of the mucosa. By contrast, UC patients had significantly reduced numbers of IL-22+ cells in actively inflamed tissues compared with both normal tissue and healthy controls. There was a selective increase in mono-IL-17-producing cells from the mucosa of UC patients with active inflammation together with increased expression of transforming growth factor (TGF)-beta and c-Maf. Increasing concentrations of TGF-beta in lamina propria mononuclear cell cultures significantly depleted Th22 cells, whereas anti-TGF-beta antibodies increased IL-22 production. When mucosal microbiota was examined, depletion of Th22 cells in actively inflamed tissue was associated with reduced populations of Clostridiales and increased populations of Proteobacteria. These results suggest that increased TGF-beta during active inflammation in UC may lead to the loss of Th22 cells in the human intestinal mucosa.

BACKGROUND: The pathogenesis of inflammatory bowel disease (IBD) may be caused by abnormal interactions between the immune system and microbiome. Recent studies using 16S ribosomal sequencing have shown that IBD is associated with dysbiosis of the microbiota. Inflammation may alter nutrient availability to adherent mucosal bacteria and impact their metabolic function. Microbial metabolites may also regulate intestinal CD4+ T cell homeostasis. We investigated the relationship between inflammation and microbial function by inferred metagenomics of the mucosal microbiota from colonic pinch biopsies of IBD patients to characterize differences in microbial metabolic pathways between inflamed and non-inflamed biopsy sites. METHODS: Institutional review board approval was obtained before involving patients in the study. Paired pinch biopsy samples of known inflammation states were analyzed from UC (23), CD (21) and controls (24) by 16S ribosomal sequencing and inferred metagenomics with comparison to pathology results and flow cytometry data. The V4 region of the 16S rRNA gene was amplified and sequenced on a MiSeq sequencer. Sequences were assigned to operational taxonomic units (OTUs) and classified taxonomically according to the Ribosomal Database Project (RDP) for use in taxonomic analysis. PICRUSt was then used with the Greengenes OTU database to generate metagenomic data, and derive relative Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway abundance information. Leukocytes were isolated from paired biopsy samples and activated with PMA/Ionomycin for intracellular cytokine (IL-22, IL-17, IFNg, IL-4 and TNFa) as well as nuclear antigen (Foxp3) analysis by multi-color flow cytometry on a BD LSRII. Active inflammation was defined by neutrophil infiltration into the epithelium, in the setting of epithelial cell damage. RESULTS: Carriage of metabolic pathways in the mucosal microbiota was relatively stable among IBD patients despite large variations in individual bacterial community structures (!