Individual Host Variation in Single-cell Responses to Enteroaggregative Escherichia coli Infection Modeled with Human Colon Organoids.

Enteroaggregative Escherichia coli (EAEC) is a leading cause of diarrhea disease worldwide. Interestingly, EAEC disease outcomes vary dramatically among infected individuals, ranging from asymptomatic colonization to acute and chronic diarrhea. While previous research has focused on EAEC virulence factors, emerging evidence suggests that host genetic and cellular background may be equally important in determining disease susceptibility. To understand host-driven disease heterogeneity, we performed single-cell RNA sequencing on human colon organoids (HCOs) derived from three healthy adult donors following EAEC 042 infection. Surprisingly, despite comparable EAEC adherence across donors, we observed striking donor-specific responses to infection at multiple levels. A total of seven distinct colonic epithelial cell clusters were identified, with striking donor-specific baseline compositions. Following infection, the HCO donors exhibited three distinct response phenotypes evident in both cell type remodeling and gene regulation: hyperresponsive, intermediate, and non-responsive. We further observed extensive donor-specific cell-cell communication networks at baseline and after EAEC infection. This study suggests that the heterogeneity in host epithelial response to EAEC infection extends to the single-cell level. These findings establish a paradigm for understanding infectious disease susceptibility through the human organoid model system. IMPORTANCE: Understanding why similar pathogen exposures produce vastly different clinical outcomes is critical for combating infectious diseases. By conducting single-cell RNA sequencing on human colon organoids derived from three different donors, we show that each donor possesses unique intrinsic cellular compositions and distinct transcriptomic responses to EAEC infection. These findings challenge the traditional pathogen-focused paradigm and highlight the critical role of host factors in infectious disease outcomes. This study also validates human organoids as a powerful platform for studying host heterogeneity, which may help predict disease susceptibility and optimize treatment for diverse patient populations in the future.