Genetic and immune determinants ofE. coliliver abscess formation

Abstract

Systemic infections can yield distinct outcomes in different tissues. In mice, intravenous inoculation of E. coli leads to bacterial replication within liver abscesses while other organs such as the spleen largely clear the pathogen. Abscesses are macroscopic necrotic regions that comprise the vast majority of the bacterial burden in the animal, yet little is known about the processes underlying their formation. Here, we characterize E. coli liver abscesses and identify host determinants of abscess susceptibility. Spatial transcriptomics revealed that liver abscesses are associated with heterogenous immune cell clusters comprised of macrophages, neutrophils, dendritic cells, innate lymphoid cells, and T-cells that surround necrotic regions of the liver. Susceptibility to liver abscesses is heightened in the C57BL/6 lineage, particularly in C57BL/6N females. Backcross analyses demonstrated that abscess susceptibility is a polygenic trait inherited in a sex-dependent manner without direct linkage to sex chromosomes. As early as one day post infection, the magnitude of E. coli replication in the liver distinguishes abscess-susceptible and abscess-resistant strains of mice, suggesting that the immune pathways that regulate abscess formation are induced within hours. We characterized the early hepatic response with single-cell RNA sequencing and found that mice with reduced activation of early inflammatory responses, such as those lacking the LPS receptor TLR4, are resistant to abscess formation. Experiments with barcoded E. coli revealed that TLR4 mediates a tradeoff between abscess formation and bacterial clearance. Together, our findings define hallmarks of E. coli liver abscess formation and suggest that hyperactivation of the hepatic innate immune response drives liver abscess susceptibility.

Innate immune responses yield tissue-specific bottlenecks that scale with pathogen dose

“…At higher doses, abscesses appeared in the livers of TLR4 Het animals, but not in TLR4 KO animals (Figure 1A, blue box). Consistent with our companion study (11), abscesses result from bacterial replication (low FP and high CFU).…”

Reverse transcriptase inhibitors prevent liver abscess formation during Escherichia coli bloodstream infection

“…Sequencing reads data have been deposited in SRA ( PRJNA952694 ) ( 9 ). All other data are included in the manuscript and/or supporting information .…”