Molecular and Functional Characterization of Human Intestinal Organoids and Monolayers for Modeling Epithelial Barrier.

BACKGROUND: Patient-derived organoid (PDO) models offer potential to transform drug discovery for inflammatory bowel disease (IBD) but are limited by inconsistencies with differentiation and functional characterization. We profiled molecular and cellular features across a range of intestinal organoid models and examined differentiation and establishment of a functional epithelial barrier. METHODS: Patient-derived organoids or monolayers were generated from control or IBD patient-derived colon or ileum and were molecularly or functionally profiled. Biological or technical replicates were examined for transcriptional responses under conditions of expansion or differentiation. Cell-type composition was determined by deconvolution of cell-associated gene signatures and histological features. Differentiated control or IBD-derived monolayers were examined for establishment of transepithelial electrical resistance (TEER), loss of barrier integrity in response to a cocktail of interferon (IFN)-γ and tumor necrosis factor (TNF)-α, and prevention of cytokine-induced barrier disruption by the JAK inhibitor, tofacitinib. RESULTS: In response to differentiation media, intestinal organoids and monolayers displayed gene expression patterns consistent with maturation of epithelial cell types found in the human gut. Upon differentiation, both colon- and ileum-derived monolayers formed functional barriers, with sustained TEER. Barrier integrity was compromised by inflammatory cytokines IFN-γ and TNF-α, and damage was inhibited in a dose-dependent manner by tofacitinib. CONCLUSIONS: We describe the generation and characterization of human colonic or ileal organoid models capable of functional differentiation to mature epithelial cell types. In monolayer culture, these cells formed a robust epithelial barrier with sustained TEER and responses to pharmacological modulation. Our findings demonstrate that control and IBD patient-derived organoids possess consistent transcriptional and functional profiles that can enable development of epithelial-targeted therapies.

QseC inhibition as an antivirulence approach for colitis-associated bacteria.

Hosts and their microbes have established a sophisticated communication system over many millennia. Within mammalian hosts, this dynamic cross-talk is essential for maintaining intestinal homeostasis. In a genetically susceptible host, dysbiosis of the gut microbiome and dysregulated immune responses are central to the development of inflammatory bowel disease (IBD). Previous surveys of stool from the T-bet-/-Rag2-/- IBD mouse model revealed microbial features that discriminate between health and disease states. Enterobacteriaceae expansion and increased gene abundances for benzoate degradation, two-component systems, and bacterial motility proteins pointed to the potential involvement of a catecholamine-mediated bacterial signaling axis in colitis pathogenesis. Enterobacteriaceae sense and respond to microbiota-generated signals and host-derived catecholamines through the two-component quorum-sensing Escherichia coli regulators B and C (QseBC) system. On signal detection, QseC activates a cascade to induce virulence gene expression. Although a single pathogen has not been identified as a causative agent in IBD, adherent-invasive Escherichia coli (AIEC) have been implicated. Flagellar expression is necessary for the IBD-associated AIEC strain LF82 to establish colonization. Thus, we hypothesized that qseC inactivation could reduce LF82's virulence, and found that an absence of qseC leads to down-regulated flagellar expression and motility in vitro and reduced colonization in vivo. We extend these findings on the potential of QseC-based IBD therapeutics to three preclinical IBD models, wherein we observe that QseC blockade can effectively modulate colitogenic microbiotas to reduce intestinal inflammation. Collectively, our data support a role for QseC-mediated bacterial signaling in IBD pathogenesis and indicate that QseC inhibition may be a useful microbiota-targeted approach for disease management.

Gut microbiota, metabolites and host immunity.

The microbiota - the collection of microorganisms that live within and on all mammals - provides crucial signals for the development and function of the immune system. Increased availability of technologies that profile microbial communities is facilitating the entry of many immunologists into the evolving field of host-microbiota studies. The microbial communities, their metabolites and components are not only necessary for immune homeostasis, they also influence the susceptibility of the host to many immune-mediated diseases and disorders. In this Review, we discuss technological and computational approaches for investigating the microbiome, as well as recent advances in our understanding of host immunity and microbial mutualism with a focus on specific microbial metabolites, bacterial components and the immune system.

Gut microbiome composition and function in experimental colitis during active disease and treatment-induced remission.

Dysregulated immune responses to gut microbes are central to inflammatory bowel disease (IBD), and gut microbial activity can fuel chronic inflammation. Examining how IBD-directed therapies influence gut microbiomes may identify microbial community features integral to mitigating disease and maintaining health. However, IBD patients often receive multiple treatments during disease flares, confounding such analyses. Preclinical models of IBD with well-defined disease courses and opportunities for controlled treatment exposures provide a valuable solution. Here, we surveyed the gut microbiome of the T-bet(-/-) Rag2(-/-) mouse model of colitis during active disease and treatment-induced remission. Microbial features modified among these conditions included altered potential for carbohydrate and energy metabolism and bacterial pathogenesis, specifically cell motility and signal transduction pathways. We also observed an increased capacity for xenobiotics metabolism, including benzoate degradation, a pathway linking host adrenergic stress with enhanced bacterial virulence, and found decreased levels of fecal dopamine in active colitis. When transferred to gnotobiotic mice, gut microbiomes from mice with active disease versus treatment-induced remission elicited varying degrees of colitis. Thus, our study provides insight into specific microbial clades and pathways associated with health, active disease and treatment interventions in a mouse model of colitis.

Bacteria, food, and cancer.

Gut microbes are essential components of the human organism-helping us metabolize food into energy, produce micronutrients, and shape our immune systems. Having a particular pattern of gut microbes is also increasingly being linked to medical conditions including obesity, inflammatory bowel disease, and diabetes. Recent studies now indicate that our resident intestinal bacteria may also play a critical role in determining one's risk of developing cancer, ranging from protection against cancer to promoting its initiation and progression. Gut bacteria are greatly influenced by diet and in this review we explore evidence that they may be the missing piece that explains how dietary intake influences cancer risk, and discuss possible prevention and treatment strategies.