Emerging concepts and shifting paradigms for understanding the microbial basis of inflammatory bowel diseases.

Inflammatory bowel diseases (IBDs) are complex immune disorders that arise at the intersection of genetic susceptibility, environmental exposures, and dysbiosis of the gut microbiota. Our understanding of the role of the microbiome in IBD has greatly expanded over the past few decades, although efforts to translate this knowledge into precision microbiome-based interventions for the prevention and management of disease have thus far met limited success. Here we survey and synthesize recent primary research in order to propose an updated conceptual framework for the role of the microbiome in IBD.

A prometabolite strategy inhibits cardiometabolic disease in an ApoE-/- murine model of atherosclerosis.

Butyrate, a microbiome-derived short-chain fatty acid with pleiotropic effects on inflammation and metabolism, has been shown to significantly reduce atherosclerotic lesions, rectify routine metabolic parameters such as low-density lipoprotein cholesterol (LDL-C), and reduce systemic inflammation in murine models of atherosclerosis. However, its foul odor, rapid metabolism in the gut and thus low systemic bioavailability limit its therapeutic effectiveness. Our laboratory has engineered an ester-linked L-serine conjugate to butyrate (SerBut) to mask its taste and odor and to coopt amino acid transporters in the gut to increase its systemic bioavailability, as determined by tissue measurements of free butyrate, produced by hydrolysis of SerBut.

NFAT5 dictates crosstalk between intestinal epithelial regenerative capacity and microbiota in murine colitis models.

Hypertonic and hyperosmolar stimuli frequently pose challenges to the intestinal tract. Therefore, a resilient epithelial barrier is essential for maintaining gut homeostasis in the presence of osmotic perturbations. NFAT5, an osmosensitive transcription factor, primarily maintains cellular homeostasis under hypertonic conditions.

Histopathologic Evaluation and Single-cell Spatial Transcriptomics of the Colon Reveal Cellular and Molecular Abnormalities Linked to J-Pouch Failure in Patients With Inflammatory Bowel Disease.

Background & Aims: Total abdominal colectomy (TAC) with a staged ileal pouch-anal anastomosis (IPAA) is a common surgical treatment for ulcerative colitis (UC). However, a significant percentage of patients experience pouch failure, leading to morbidity. This retrospective case-control study identified histopathologic features of the TAC specimen associated with pouch failure and investigated the molecular mechanisms of this susceptibility using single-cell spatial transcriptomics.

Microbiome mismatches from microbiota transplants lead to persistent off-target metabolic and immunomodulatory effects.

Fecal microbiota transplant (FMT) is an increasingly used intervention, but its suitability to restore regional gut microbiota, particularly in the small bowel (SB), must be questioned because of its predominant anaerobic composition. In human subjects receiving FMT by upper endoscopy, duodenal engraftment of anaerobes was observed after 4 weeks. We hypothesized that peroral FMTs create host-microbe mismatches that impact SB homeostasis.

Protocol to characterize longitudinal gut motility in mice using transit time, tissue harvest, and whole-mount immunostaining.

Transit time is a key in vivo metric of gastrointestinal (GI) motility, which is a physiologic readout of cellular communication within the enteric system. Here, we present a protocol to characterize longitudinal gut motility in mice. We describe steps for transit testing, whole-mount immunostaining, and tissue harvest.

Fecal Microbial Profiles and Short-Chain Fatty Acid/Bile Acid Metabolomics in Patients With Age-Related Macular Degeneration: A Pilot Study.

Purpose: Age-related macular degeneration (AMD) is a multifactorial disease, and studies have implicated the role of gut microbiota in its pathogenesis. However, characterization of microbiome dysbiosis and associated microbial-derived metabolomic profiles across AMD stages remains unknown. In this pilot study, we explored how gut microbiome composition and gut-derived metabolites differ in AMD.

Histopathologic Evaluation and Single-Cell Spatial Transcriptomics of the Colon Reveal Cellular and Molecular Abnormalities Linked to J-Pouch Failure in Patients with Inflammatory Bowel Disease.

Background And Aims: Total abdominal colectomy (TAC) with a staged ileal pouch-anal anastomosis (IPAA) is a common surgical treatment for ulcerative colitis (UC). However, a significant percentage of patients experience pouch failure, leading to morbidity. This retrospective case-control study identified histopathological features of the TAC specimen associated with pouch failure and investigated the molecular mechanisms of this susceptibility using single-cell spatial transcriptomics.

Multiomic analysis reveals cellular, transcriptomic and epigenetic changes in intestinal pouches of ulcerative colitis patients.

Total proctocolectomy with ileal pouch anal anastomosis is the standard of care for patients with severe ulcerative colitis. We generated a cell-type-resolved transcriptional and epigenetic atlas of ileal pouches using scRNA-seq and scATAC-seq data from paired biopsy samples of the ileal pouch and the ileal segment above the pouch (pre-pouch) from patients (male=4, female=2), and paired biopsies of the terminal ileum and ascending colon from healthy individuals (male=3, female=3) serving as reference. Our study finds an additional population of absorptive and secretory epithelial cells within the pouch but not the pre-pouch.

Cell-type-resolved chromatin accessibility in the human intestine identifies complex regulatory programs and clarifies genetic associations in Crohn's disease.

Crohn's disease (CD) is a complex inflammatory bowel disease resulting from an interplay of genetic, microbial, and environmental factors. Cell-type-specific contributions to CD etiology and genetic risk are incompletely understood. Here we built a comprehensive atlas of cell-type- resolved chromatin accessibility comprising 557,310 candidate cis-regulatory elements (cCREs) in terminal ileum and ascending colon from patients with active and inactive CD and healthy controls.

A metagenome-assembled genome inventory for children reveals early-life gut bacteriome and virome dynamics.

Existing microbiota databases are biased toward adult samples, hampering accurate profiling of the infant gut microbiome. Here, we generated a metagenome-assembled genome inventory for children (MAGIC) from a large collection of bulk and viral-like particle-enriched metagenomes from 0 to 7 years of age, encompassing 3,299 prokaryotic and 139,624 viral species-level genomes, 8.5% and 63.

Microbiota-dependent early-life programming of gastrointestinal motility.

Gastrointestinal microbes modulate peristalsis and stimulate the enteric nervous system (ENS), whose development, as in the central nervous system (CNS), continues into the murine postweaning period. Given that adult CNS function depends on stimuli received during critical periods of postnatal development, we hypothesized that adult ENS function, namely motility, depends on microbial stimuli during similar critical periods. We gave fecal microbiota transplantation (FMT) to germ-free mice at weaning or as adults and found that only the mice given FMT at weaning recovered normal transit, while those given FMT as adults showed limited improvements.

Diet outperforms microbial transplant to drive microbiome recovery post-antibiotics.

High-fat, low-fiber Western-style diets (WD) induce microbiome dysbiosis characterized by reduced taxonomic diversity and metabolic breadth, which in turn increases risk for a wide array of metabolic, immune and systemic pathologies. Recent work has established that WD can impair microbiome resilience to acute perturbations like antibiotic treatment, although we know little about the mechanism of impairment and the specific host consequences of prolonged post-antibiotic dysbiosis. Here, we characterize the trajectory by which the gut microbiome recovers its taxonomic and functional profile after antibiotic treatment in mice on regular chow (RC) and WD, and find that only mice on RC undergo a rapid successional process of recovery.

Maternal gestational diabetes mellitus associates with altered gut microbiome composition and head circumference abnormalities in male offspring.

The impact of gestational diabetes mellitus (GDM) on maternal or infant microbiome trajectory remains poorly understood. Utilizing large-scale longitudinal fecal samples from 264 mother-baby dyads, we present the gut microbiome trajectory of the mothers throughout pregnancy and infants during the first year of life. GDM mothers had a distinct microbiome diversity and composition during the gestation period.

Endoscopic Normalization and Transition of J-Pouch Phenotypes Over Time in Patients With Inflammatory Bowel Disease.

Background: Patients with inflammatory bowel disease (IBD) who undergo proctocolectomy with ileal pouch-anal anastomosis may develop pouchitis. We previously proposed a novel endoscopic classification of pouchitis describing 7 phenotypes with differing outcomes. This study assessed phenotype transitions over time.

A cryptic plasmid is among the most numerous genetic elements in the human gut.

Plasmids are extrachromosomal genetic elements that often encode fitness-enhancing features. However, many bacteria carry "cryptic" plasmids that do not confer clear beneficial functions. We identified one such cryptic plasmid, pBI143, which is ubiquitous across industrialized gut microbiomes and is 14 times as numerous as crAssphage, currently established as the most abundant extrachromosomal genetic element in the human gut.

Sodium oligomannate alters gut microbiota, reduces cerebral amyloidosis and reactive microglia in a sex-specific manner.

It has recently become well-established that there is a connection between Alzheimer's disease pathology and gut microbiome dysbiosis. We have previously demonstrated that antibiotic-mediated gut microbiota perturbations lead to attenuation of Aβ deposition, phosphorylated tau accumulation, and disease-associated glial cell phenotypes in a sex-dependent manner. In this regard, we were intrigued by the finding that a marine-derived oligosaccharide, GV-971, was reported to alter gut microbiota and reduce Aβ amyloidosis in the 5XFAD mouse model that were treated at a point when Aβ burden was near plateau levels.

Microbially catalyzed conjugation of GABA and tyramine to bile acids.

Bile acids (BAs) are cholesterol-derived molecules that aid in digestion and nutrient absorption, regulate host metabolic processes, and influence physiology of the gut microbiota. Both the host and its microbiome contribute to enzymatic modifications that shape the chemical diversity of BAs in the gut. Several bacterial species have been reported to conjugate standard amino acids to BAs, but it was not known if bacteria conjugate BAs to other amine classes.

Bile acid fitness determinants of a isolate from a human pouchitis patient.

The Gram-negative bacterium is a common member of the human gut microbiota that colonizes multiple host niches and can influence human physiology through a variety of mechanisms. Identification of genes that enable to grow across a range of host environments has been impeded in part by the relatively limited genetic tractability of this species. We have developed a high-throughput genetic resource for a strain isolated from a UC pouchitis patient.