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Mitochondrial C5aR1 activity in macrophages controls IL-1β production underlying sterile inflammation

ABSTRACT: While serum-circulating complement destroys invading pathogens, intracellularly active complement, termed the ‘complosome’, functions as a vital orchestrator of cell-metabolic events underlying T cell effector responses. Whether intracellular complement is also non-redundant for the activity of myeloid immune cells is currently unknown. Here, we show that monocytes and macrophages constitutively express complement component (C) 5 and can generate autocrine C5a via formation of an intracellular C5 convertase. Further, cholesterol crystal-sensing by macrophages induces C5aR1 signaling on mitochondrial membranes, which shifts ATP production via reverse electron chain flux towards reactive oxygen species (ROS) production and anaerobic glycolysis to favor IL-1β production. Consequently, atherosclerosis-prone mice lacking macrophage-specific C5ar1 had ameliorated cardiovascular disease on a high-cholesterol diet. Conversely, inflammatory gene signatures and IL-1β produced by cells in unstable atherosclerotic plaques of patients were normalized by a specific cell-permeable C5aR1 antagonist. Deficiency of the macrophage cell autonomous C5 system also protected mice from crystal nephropathy mediated by folic acid. These data demonstrate unexpected intracellular formation of a C5 convertase and identify C5aR1 as a direct modulator of mitochondrial function and inflammatory output from myeloid cells. Together, these findings suggest that the complosome is a novel contributor to the biologic processes underlying sterile inflammation and indicate that targeting this system could be beneficial in macrophage-dependent diseases, such as atherosclerosis.

ORGANISM(S): Homo sapiens

PROVIDER: GSE162389 | GEO | 2021/12/30

REPOSITORIES: GEO

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