immunoHuMiX: A personalizable gut-on-chip model for unraveling human microbiome–immune interactions

An individual's immune status is an essential factor affecting the efficacy of microbiome-based therapies. To enable representative studies of microbiome–immune system interactions, we developed protocols to facilitate the coculture of intestinal epithelial cells and human peripheral blood mononuclear cells (PBMCs) in our microphysiological model of the human gut, HuMiX. Using the resulting immunoHuMiX model, we assessed responses to human–microbial cocultures with a probiotic mixture comprised of 17 strictly anaerobic Clostridial strains (17-mix). We demonstrated the ability of our model to sustain metabolically active microbiota, while maintaining human cell viability, and generated relevant read-outs for host–microbiome interaction studies. The composition of the strain mixture was not affected by the individual sources of PBMCs, and the abundances of the different immune cell populations were comparable when incubated with or without the 17-mix after 24 h in the system, and between individuals. We observed increased cytokine production, PBMC viability, and PBMC cell counts upon coculture with the 17-mix, thereby demonstrating immune sensing of the microbiota by the PBMCs. In summary, our immunoHuMiX model provides an important personalizable tool for screening microbiota-driven immune responses.