Discrimination of cell-intrinsic and environment-dependent effects of natural genetic variation on Kupffer cell epigenomes and transcriptomes

Noncoding genetic variation drives phenotypic diversity, but underlying mechanisms and affected cell types are incompletely understood. Here, investigation of effects of natural genetic variation on the epigenomes and transcriptomes of Kupffer cells derived from inbred mouse strains identified strain-specific environmental factors influencing Kupffer cell phenotypes, including leptin signaling in Kupffer cells from a steatohepatitis-resistant strain. Cell-autonomous and non-cell-autonomous effects of genetic variation were resolved by analysis of F1 hybrid mice and cells engrafted into an immunodeficient host. During homeostasis, non-cell-autonomous trans effects of genetic variation dominated control of Kupffer cells, while strain-specific responses to acute lipopolysaccharide injection were dominated by actions of cis-acting effects modifying response elements for lineage-determining and signal-dependent transcription factors. These findings demonstrate that epigenetic landscapes report on trans effects of genetic variation and serve as a resource for deeper analyses into genetic control of transcription in Kupffer cells and macrophages in vitro. The mechanisms by which noncoding genetic variation shapes tissue macrophage phenotypic diversity remain obscure. Glass and colleagues define cell-intrinsic and environmental effects contributing to genetic control of Kupffer cell transcription.

Automated summary

This study reveals the genetic regulatory mechanisms of transcription in macrophages and identifies the impact of environmental factors on macrophage phenotypes. Non-cell autonomous effects of genetic variation dominate the control of macrophages during homeostasis, while cis-acting effects play a major role in strain-specific responses to acute stimulation.