Description
Normal arteries contain a large population of tissue resident macrophages (M). 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 M as a distinct population among tissue M. Ontologically, arterial M arise before birth, though CX3CR1-, Csf1r-, and Flt3-driven fate mapping approaches demonstrate M colonization occurs through successive contributions of yolk sac (YS) and conventional hematopoiesis. In adulthood, arterial M renewal is driven by local proliferation rather than monocyte recruitment from the blood. Proliferation sustains M not only during steady state conditions, but mediates their rebound after severe depletion following sepsis. Importantly, the return of arterial M to functional homeostasis after infection is rapid; repopulated M exhibit a transcriptional program similar to resting M and efficiently phagocytose bacteria. Collectively, our data provide a detailed framework for future studies of arterial M function in health and disease.