Lifestyle-mediated shifts in the gut microbiome and host genetics modulate gene expression in intestinal organoids

Industrialization-associated shifts in the gut microbiome have been linked to disease, but the mechanisms by which microbial communities influence host gene regulation remain poorly understood. We developed a live microbiome-colonic organoid (colonoid) co-culture system to investigate genotype-dependent host responses to gut microbial community variation. Colonoid 2D monolayers from healthy donors were co-cultured with live gut microbial communities from individuals living urban or rural lifestyles, followed by RNA-sequencing. Urban and rural microbiomes elicited largely shared transcriptional responses, however they induced distinct host genetic effects on gene expression. We identified 511 host genes with microbiome-dependent allele-specific expression (ASE) which were involved in epithelial architecture, cell-matrix interactions and structural integrity. Notably, 149 host genes had distinct allelic effects between Urban and Rural microbiomes (urban-rural condition specific ASE or cASE), revealing genotype-dependent host responses to lifestyle-associated microbiomes. Urban-rural cASE was associated with microbial community composition, predominantly involving Prevotella and Bacteroides species. Targeted Prevotella copri spike-in recapitulated Prevotella-associated allelic effects at specific loci, including one in the IBD-associated autophagy gene, ATG4B. Together, these findings establish an experimental framework to investigate genotype-by-microbiome interactions, and demonstrate that lifestyle-mediated shifts in the microbiome modify host cis-regulatory genetic effects on gene expression.