Non-canonical glutamine transamination sustains efferocytosis by coupling redox buffering to oxidative phosphorylation

Merlin et al. find that non-canonical glutamine transamination is required for macrophage efferocytosis in atherosclerotic plaques by sustaining redox buffering and fueling energy production for cytoskeletal rearrangements. Macrophages rely on tightly integrated metabolic rewiring to clear dying neighboring cells by efferocytosis during homeostasis and disease. Here we reveal that glutaminase-1-mediated glutaminolysis is critical to promote apoptotic cell clearance by macrophages during homeostasis in mice. In addition, impaired macrophage glutaminolysis exacerbates atherosclerosis, a condition during which, efficient apoptotic cell debris clearance is critical to limit disease progression. Glutaminase-1 expression strongly correlates with atherosclerotic plaque necrosis in patients with cardiovascular diseases. High-throughput transcriptional and metabolic profiling reveals that macrophage efferocytic capacity relies on a non-canonical transaminase pathway, independent from the traditional requirement of glutamate dehydrogenase to fuel alpha-ketoglutarate-dependent immunometabolism. This pathway is necessary to meet the unique requirements of efferocytosis for cellular detoxification and high-energy cytoskeletal rearrangements. Thus, we uncover a role for non-canonical glutamine metabolism for efficient clearance of dying cells and maintenance of tissue homeostasis during health and disease in mouse and humans.

Automated summary

Non-canonical glutamine metabolism is essential for efficient clearance of dying cells by macrophages in atherosclerotic plaques. This process involves redox buffering, energy production, and cytoskeletal rearrangements. High expression of glutaminase-1 is associated with atherosclerotic plaque necrosis in cardiovascular disease patients.