Highlights d We developed a model of the human gut-liver axis, including adaptive immune cells d Interaction between gut and liver MPSs increases metabolism and reduces inflammation d SCFAs reduce innate inflammation of the UC gut in absence of Treg and Th17 cells d Acute CD4 + T cell-mediated inflammation is exacerbated by SCFAs

No abstract

Many human gut bacteria of clinical relevance are extremely oxygen sensitive, hampering the investigation of crosstalk with host cells. Zhang et al. developed a gut-microbe physiomimetic platform for long-term continuous co-culture of super oxygen-sensitive bacterial species with primary human colon epithelium in the context of inflammation.

Association between the microbiome, IBD and liver diseases are known, yet cause and effect remain elusive. By connecting human microphysiological systems of the gut, liver and circulating Treg/Th17 cells, we modeled progression of ulcerative colitis (UC) ex vivo. We show that microbiome-derived short-chain fatty acids (SCFA) may either improve or worsen disease severity, depending on the activation state of CD4 T cells. Employing multiomics, we found SCFA reduced innate activation of the UC gut and increased hepatic metabolism. However, during acute T cell-mediated inflammation, SCFA exacerbate CD4 T cell effector function leading to gut barrier disruption and liver damage. These paradoxical findings underscore the emerging utility of human physiomimetic technology to study causality and temporal facets of gut-liver axis related diseases where animal models leave ambiguity.

AbstractThe gut microbiome plays an important role in human health and disease. Gnotobiotic animal and in vitro cell-based models provide some informative insights into mechanistic crosstalk. However, there is no existing system for a chronic co-culture of a human colonic mucosal barrier with super oxygen-sensitive commensal microbes, hindering the study of human-microbe interactions in a controlled manner. Here, we investigated the effects of an abundant super oxygen-sensitive commensal anaerobe, Faecalibacterium prausnitzii, on a primary human mucosal barrier using a Gut-MIcrobiome (GuMI) physiome platform that we designed and fabricated. Chronic continuous co-culture of F. prausnitzii for two days with colon epithelia, enabled by continuous flow of completely anoxic apical media and aerobic basal media, resulted in a strictly anaerobic apical environment fostering growth of and butyrate production by F. prausnitzii, while maintaining a stable colon epithelial barrier. We identified elevated differentiation and hypoxia-responsive genes and pathways in the platform compared with conventional aerobic static culture of the colon epithelia, attributable to a combination of anaerobic environment and continuous medium replenishment. Furthermore, we demonstrated anti-inflammatory effects of F. prausnitzii through HDAC and the TLR-NFKB axis. Finally, we identified that butyrate largely contributes to the anti-inflammatory effects by downregulating TLR3 and TLR4. Our results are consistent with some clinical observations regarding F. prausnitzii, thus motivating further studies employing this platform with more complex engineered colon tissues for understanding the interaction between the human colonic mucosal barrier and microbiota, pathogens, or engineered bacteria.