Expression data from Aortic Macrophages. Mus musculus

Normal arteries contain a large population of tissue resident macrophages (MΦ). Their origins, as well as the mechanisms that sustain them during homeostasis and disease, however, are poorly understood. Gene expression profiling, we show, identifies arterial MΦ as a distinct population among tissue MΦ. Ontologically, arterial MΦ arise before birth, though CX3CR1-, Csf1r-, and Flt3-driven fate mapping approaches demonstrate MΦ colonization occurs through successive contributions of yolk sac (YS) and conventional hematopoiesis. In adulthood, arterial MΦ renewal is driven by local proliferation rather than monocyte recruitment from the blood. Proliferation sustains MΦ not only during steady state conditions, but mediates their rebound after severe depletion following sepsis. Importantly, the return of arterial MΦ to functional homeostasis after infection is rapid; repopulated MΦ exhibit a transcriptional program similar to resting MΦ and efficiently phagocytose bacteria. Collectively, our data provide a detailed framework for future studies of arterial MΦ function in health and disease. Overall design: Aortic macrophages (CD11bhighF4/80highCD45+MerTK+CD64+) were isolated from C57/B6 wild-type male mice aged 6-8 weeks before and 7 days after induction of sepsis by cecal puncture. 18-20 aortas were pooled per sample. Each condition contained three biological replicates.