Hyperinflammation by Human Macrophages Induced by SARS-CoV-2 Anti-Spike IgG Is Dependent on Glucose and Fatty Acid Metabolism.

Severe COVID-19 is an immunological disorder characterized by excessive immune activation following infection with SARS-CoV-2, which typically occurs around the time of seroconversion. Anti-spike IgG of critically ill COVID-19 patients induces excessive inflammation by activation of Fc gamma receptors (FcγRs) on human alveolar macrophages, leading to tissue damage, pulmonary edema, and coagulopathy. While metabolic reprogramming of immune cells is critical for the induction of inflammatory responses, still little is known about the metabolic pathways that are involved in COVID-19-specific hyperinflammation. In this study, we identified that anti-spike IgG immune complexes (ICs) induce rapid metabolic reprogramming of alveolar macrophages, which is essential for the induction of inflammation. Through functional inhibition, we identified that glycolysis, fatty acid synthesis, and pentose phosphate pathway (PPP) activation are critical for anti-spike IgG-induced hyperinflammation. Remarkably, while excessive proinflammatory cytokine production by macrophages is critically dependent on simultaneous stimulation with viral stimuli and anti-spike IgG complexes, we show that the required metabolic reprogramming is specifically driven by anti-spike IgG complexes. These findings provide new insights into the metabolic pathways driving hyperinflammation by macrophages in the context of severe COVID-19. Targeting of these pathways may reveal new possibilities to counteract pathological inflammatory responses in severe COVID-19 and related diseases.