CD163 and Tim-4 identify resident intestinal macrophages across sub-tissular regions that are spatially regulated by TGF-β

Le résumé fourni par la source

Abstract In bodily organs, macrophages are localised in poorly understood tissular and sub-tissular niches associated with defined macrophage ontogeny and activity. In the intestine, a paradigm is emerging that long-lived macrophages are dominantly present in the muscular layer, while highly monocyte-replenished populations are found in the lamina propria beneath the epithelial barrier. Whether longevity is restricted in such a simplified manner has not been well explored. Moreover, the impact of specific gut-associated factors on long-lived macrophage functionality and niche occupancy is unknown. We generated sc-RNA-Seq data from wild-type and Ccr2 −/− mice to identify phenotypic features of long-lived macrophage populations in distinct intestinal niches and identified CD163 as a useful marker to distinguish submucosal/muscularis (S/M) from lamina propria (LP) macrophages. Challenging the emerging paradigm, long-lived macrophages, identified by Tim-4 expression, were found in the LP and S/M. Long-lived LP macrophages are restrained in their response to proinflammatory stimulation compared to short-lived populations in the same location, and to the long-lived population within the S/M. Employing a novel Timd4 cre Tgfbr2 fl/fl mouse line we demonstrate distinct functions of TGF-β on long-lived macrophages in these two compartments. Importantly, in Timd4 cre Tgfbr2 fl/fl mice, zonation of CD163 + macrophages in the S/M was lost, suggesting TGF-β plays an unappreciated role in positioning of macrophages in the tissue. These data highlight the importance of considering ontogeny and niche when assessing the action of key intestinal regulatory signals.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.