Erroneous efferocytosis of live neutrophils during infection prevents the resolution of inflammation [RNAseq_dual_species]

Here, we show that neutrophils infected with the bacterial pathogenPorphyromonas gingivalis (Pg) are internalized alive by macrophages in a manner that bypasses all known efferocytic receptor-ligand interactions. Live cell uptake was mediated by the proteolysis of neutrophil granule proteins by the Pg protease RgpB. Subsequent translocation and recognition of these RgpB-generated efferocytic ligands by macrophage complement receptor 3 (CR3) receptors led to the internalization of live neutrophils by macrophages. Contrary to the immunosuppression induced by apoptotic cells, efferocytosis of live neutrophils was highly inflammatory. Thus, our data show a novel immune subversion strategy employed by a bacterial pathogen that utilizes a previously unknown receptor-ligand interaction for the efferocytosis of live cells and consequently dysregulates the resolution of inflammation.