Dysbiosis in Metabolic Genes of the Gut Microbiomes of Patients with an Ileo-anal Pouch Resembles That Observed in Crohn's Disease.

Crohn's disease (CD), ulcerative colitis (UC), and pouchitis are multifactorial and chronic inflammatory bowel diseases (IBD). Pouchitis develops in former UC patients after proctocolectomy and ileal-pouch-anal anastomosis and is characterized by inflammation of the previously normal small intestine comprising the pouch. The extent to which microbial functional alteration (dysbiosis) in pouchitis resembles that of CD or UC has not been investigated, and the pathogenesis of pouchitis remains unknown. We collected 208 fecal metagenomes from 69 patients with a pouch (normal pouch and pouchitis) and compared them to publicly available metagenomes of patients with CD (n = 88), patients with UC (n = 76), and healthy controls (n = 56). Patients with pouchitis presented the highest alterations in species, metabolic pathways, and enzymes, which was correlated with intestinal inflammation. Ruminococcus gnavus strains encoding mucin-degrading glycoside hydrolases were highly enriched in pouchitis. Butyrate and secondary bile acid biosynthesis pathways were decreased in IBD phenotypes and were especially low in pouchitis. Pathways such as amino acid biosynthesis and degradation of aromatic compounds and sugars, encoded by members of the Enterobacteriaceae, were enriched in pouch and CD but not in UC. We developed microbial feature-based classifiers that can distinguish between patients with a normal pouch and pouchitis and identified species and genes that were predictive of pouchitis. We propose that the noninflamed pouch is already dysbiotic and microbially is similar to CD. Our study reveals microbial functions that outline the pathogenesis of pouchitis and suggests bacterial groups and functions that could be targeted for intervention to attenuate small intestinal inflammation present in pouchitis and CD.IMPORTANCE Crohn's disease (CD), ulcerative colitis (UC), and pouchitis are chronic inflammatory conditions of the bowel. Pouchitis develops in former UC patients after proctocolectomy and ileal-pouch-anal anastomosis and is characterized by inflammation of the previously normal small intestine comprising the pouch. The extent to which microbial dysbiosis in patients with pouchitis resembles that of CD or UC and the pathogenesis of pouchitis remains unclear. We investigated the functions in the gut microbiomes of these patients using metagenomics. We found that the noninflamed pouch is already dysbiotic and microbially is similar to CD. Our study reveals microbial functions with a potential role in pouchitis pathogenesis such as depletion in butyrate and secondary bile acid synthesis and enrichment of amino acid synthesis and degradation of aromatic compounds, encoded by members of the Enterobacteriaceae We developed microbial feature-based classifiers that can distinguish between patients with a normal pouch and pouchitis and identified species and genes that were predictive of pouchitis. We suggest species and functions that could be targeted for intervention to attenuate small intestinal inflammation present in pouchitis and CD.

Early Indolent Course of Crohn's Disease in Newly Diagnosed Patients Is Not Rare and Possibly Predictable.

BACKGROUND & AIMS: The early stages of Crohn's disease (CD) course are heterogeneous, and it is a challenge to predict the course of disease in patients with new diagnosis. METHODS: We performed an observational longitudinal study of 156 adults (79 male; median age, 27.7 years; 57 treatment naïve) with newly diagnosed CD (within 6 months of enrollment), referred from medical centers and community clinics in Israel from 2013 through 2017. Study participants each received semi-annual scheduled evaluations. Indolent disease was defined as a disease course without need for strict interventions to control complicated course of CD (hospitalization or surgery, or decision to start steroid, immunomodulator, or biologic therapy). Cox regression and receiver operating characteristic analyses were used to identify factors associated with early indolent or complicated course of CD. We validated our findings in an independent cohort of patients with CD from a separate medical center in Israel in 2018. RESULTS: Over a median follow-up period of 17.2 months (interquartile range, 8.8-23.8 months), 52 patients (33.3%) had an indolent course of CD, 29 (18.5%) required hospitalizations, and 75 (48%) were recommended to start steroid, immunomodulator, or biologic therapies. The median time to first intervention was 3.4 months (95% CI, 2.4-4.4). We developed a model based on clinical factors that identified 4 factors associated with complicated course in treatment-naïve patients: body mass index <25 kg/m2 (hazard ratio [HR], 2.45; 95% CI, 1.07-5.43; P = .033), serum level of vitamin B12 <350 pg/mL (HR, 2.78; 95% CI, 1.21-6.41; P = .016), white blood cells ≥7 × 103/µL (HR, 2.419; 95% CI, 1.026-5.703; P = .044), and serum level of ALT ≥25 IU/L (HR, 2.680; 95% CI, 1.186-6.058; P = .018). This model discriminated between patients with vs without a complicated course of disease with 90% and 89% accuracy at 6 and 12 months after diagnosis, respectively. A validation cohort demonstrated a discriminatory ability of 79% at 3 months after diagnosis, and a nomogram was constructed. CONCLUSIONS: In an observational longitudinal study of 156 patients with newly diagnosed CD, we found that one third have an early indolent course of disease. We identified factors that can be measured at diagnosis to identify patients at risk for an early complicated course-these might be used in patient management and selection of treatment.

Predominantly Antibiotic-resistant Intestinal Microbiome Persists in Patients With Pouchitis Who Respond to Antibiotic Therapy.

BACKGROUND & AIMS: Pouchitis that develops in patients with ulcerative colitis after total proctocolectomy and ileal pouch anal anastomosis is usually treated with antibiotics. Some patients have recurrence of flares, or become antibiotic-dependent, and require repeated courses or prolonged periods of antibiotic therapy. We investigated microbial factors associated with response to antibiotic treatment and development of antibiotic dependence in patients with pouchitis. METHODS: We performed a prospective study of 49 patients who had undergone pouch surgery at a tertiary center. Disease activity was determined based on clinical, endoscopic, and histologic criteria. Pouch phenotype was defined as recurrent-acute pouchitis (n = 6), chronic pouchitis and Crohn's-like disease of the pouch (n = 27), normal pouch from patient with ulcerative colitis (n = 10), and normal pouch from patient with familial adenomatous polyposis (n = 6). Fecal samples (n = 234) were collected over time during or in the absence of antibiotic treatment (ciprofloxacin and/or metronidazole). Thirty-three patients were treated with antibiotics, for a median of 425 days of cumulative antibiotic therapy, during follow-up. Calprotectin was measured and fecal DNA was sequenced using shotgun metagenomics and analyzed with specifically designed bioinformatic pipelines. Bacterial strains were isolated from fecal samples. We assessed their ciprofloxacin resistance and ability to induce secretion of inflammatory cytokines by HT-29 intestinal epithelial cells. RESULTS: Most antibiotic-treated patients (79%) had a clinical response to each course of antibiotics; however, 89% of those who completed a 4-week course relapsed within 3 months. Median calprotectin levels decreased by 40% in response to antibiotics. Antibiotic treatment reduced disease-associated bacteria such as Clostridium perfringens, Ruminococcus gnavus, and Klebsiella pneumoniae, but also beneficial species, such as Faecalibacterium prausnitzii. The microbiomes of antibiotic-responsive patients were dominated by facultative anaerobic genera (Escherichia, Enterococcus, and Streptococcus), with multiple ciprofloxacin-resistance mutations in drug target genes and confirmed drug resistance. However, these strains had lower potential for virulence and did not induce secretion of inflammatory cytokines by epithelial cells. After antibiotic cessation, patients had an abrupt shift in microbiome composition, with blooms of oral and disease-associated bacteria. In addition, antibiotic treatment enriched for strains that acquired multidrug resistance loci, encoding enzymes that confer resistance to nonrelated antibiotics, including extended-spectrum beta-lactamases. CONCLUSIONS: The efficacy of antibiotic treatment of pouchitis might be attributed to the establishment of an antibiotic-resistant microbiome with low inflammatory potential. This microbiome might provide resistance against colonization by bacteria that promote inflammation. To avoid progression to antibiotic-dependent disease and its consequences, strategies such as short-term alternating antibiotics and nutrition- and microbiome-based interventions should be considered.