Neonatal imprinting of alveolar macrophages via neutrophil-derived 12-HETE

Resident-tissue macrophages (RTMs) arise from embryonic precursors1,2, yet the developmental signals that shape their longevity remain largely unknown. Here we demonstrate in mice genetically deficient in 12-lipoxygenase and 15-lipoxygenase (Alox15−/− mice) that neonatal neutrophil-derived 12-HETE is required for self-renewal and maintenance of alveolar macrophages (AMs) during lung development. Although the seeding and differentiation of AM progenitors remained intact, the absence of 12-HETE led to a significant reduction in AMs in adult lungs and enhanced senescence owing to increased prostaglandin E2 production. A compromised AM compartment resulted in increased susceptibility to acute lung injury induced by lipopolysaccharide and to pulmonary infections with influenza A virus or SARS-CoV-2. Our results highlight the complexity of prenatal RTM programming and reveal their dependency on in trans eicosanoid production by neutrophils for lifelong self-renewal.


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March 2021
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Lung tissues were perfused with 10mL of PBS, harvested and minced before collagenase IV digestion (150U/mL, Sigma) for 1 hour at 37C. Lungs were filtered through a 70μm nylon mesh and red blood cells were lysed. Peritoneal cells were obtained following lavage with 5ml of cold PBS injected ip. Cells were then spun down, and red blood cells lysed. Spleen cells were obtained by crushing the spleen on a 70μm nylon mesh followed by red blood cells lysis. Liver cells were obtained after mincing and digestion with collagenase VIII (1mg/ml, Sigma) for 30min at 37C. The cells were passed sequentially through 100 and 70μm cell strainers before red blood cell lysis. Brain cells were obtained after passing through 100 and 70μm cell strainers followed by Percoll gradient (30% and 70% solutions). Total lung, peritoneal, liver, brain and spleen cell counts were determined with a hemocytometer and 0.5-2 million cells were used for staining. Tick this box to confirm that a figure exemplifying the gating strategy is provided in the Supplementary Information.