Coordinated Chemokine Expression Defines Macrophage Subsets Across Tissues

Abstract

Tissue-resident macrophages in the lung comprising alveolar and interstitial macrophages (IMs) display a high degree of heterogeneity. In general, macrophage heterogeneity is thought to arise from various forms of activation that are heavily confounded by the recruitment of monocytes to the tissue-resident macrophage pool. To better understand the functional heterogeneity of IMs in the lung, we profiled the transcription of resident CD206hiand CD206loIMs under steady-state and inflammatory conditions, excluding recruited macrophages. Rather than observing conventionalin vitroM1 and M2 activation states, we identified seven chemokine-expressing IM subsets: IMck1 (Ccl2, Ccl7, Ccl12,and someCxcl14), IMck2-4 (Ccl3, Ccl4, Ccl5, Cxcl1, Cxcl2,andCxcl3), IMck5 (Ccl8), IMck6 (Ccl6andCcl9), IMck7 (Cxcl9andCxcl10), IMck8 (Cxcl13), and IMck9 (Ccl24), which were found in steady-state or induced by acute inflammation. Beyond the mouse lung, similar coordinated chemokine signatures were observed in macrophages and monocytes from other tissues and across species. Although all IMs expressedPf4(CXCL4), mainly CD206hiIMs were selectively depleted inPf4CreR26EYFP-DTRmice. Loss of CD206hiIMs resulted in significantly reduced inflammatory cell influx in allergen- and infection-driven models, as well as significantly diminished tertiary lymphoid formation and subsequent accumulation of GL7+germinal center B cells. Overall, our study highlights a division of labor among interstitial macrophages, reflected by the coordinated production of chemokines to control inflammatory cell influx and organize tertiary lymphoid tissue architecture.One Sentence SummaryThe study highlights a division of labor among interstitial macrophages, reflected by the coordinated production of chemokines to control inflammatory cell influx and organize tertiary lymphoid tissue architecture.

Systematic perturbation screens decode regulators of inflammatory macrophage states and identify a role forTNFmRNA m6A modification

“…Here, we describe a funneled, cross-species genomics approach combining complementary CRISPR loss-of-function screens with functional profiling of cytokine secretion in IFN-γ primed 4 macrophages. Inflammatory macrophage states harbor distinct cytokine profiles 18,19 . Similar to the utility of cytokine profiles in defining T helper cell subsets, macrophage cytokine secretion profiles can provide an accessible and relevant readout of macrophage states, thereby facilitating the identification of the underlying regulatory circuits associated with specific functional subsets.…”

“…The copyright holder for this preprint (which this version posted April 14, 2024. ; https://doi.org/10.1101/2024.04.12.589122 doi: bioRxiv preprint 4 macrophages. Inflammatory macrophage states harbor distinct cytokine profiles 18,19 . Similar to the utility of cytokine profiles in defining T helper cell subsets, macrophage cytokine secretion profiles can provide an accessible and relevant readout of macrophage states, thereby facilitating the identification of the underlying regulatory circuits associated with specific functional subsets.…”