Sema7A is crucial for resolution of severe inflammation

Endogenous mediators regulating acute inflammatory responses in both the induction and resolution phases of inflammatory processes are pivotal in host defense and tissue homeostasis. Recent studies have identified neuronal guidance proteins characterized in axonal development that display immunomodulatory functions. Here, we identify the neuroimmune guidance cue Semaphorin 7A (Sema7A), which appears to link macrophage (M Phi) metabolic remodeling to inflammation resolution. Sema7A orchestrated M Phi chemotaxis and chemokinesis, activated M Phi differentiation and polarization toward the proresolving M2 phenotype, and promoted leukocyte clearance. Peritoneal M Phi(sema7A-/-) displayed metabolic reprogramming, characterized by reductions in fatty acid oxidation and oxidative phosphorylation, increases in glycolysis and the pentose phosphate pathway, and truncation of the tricarboxylic acid cycle, which resulted in increased levels of the intermediates succinate and fumarate. The low accumulation of citrate in M Phi(sema7A-/-) correlated with the decreased synthesis of prostaglandins, leading to a reduced impact on lipid-mediator class switching and the generation of specialized pro resolving lipid mediators. Signaling network analysis indicated that Sema7A induced the metabolic reprogramming of M Phi by activating the mTOR-and AKT2-signaling pathways. Administration of Sema7A(SL4cd) orchestrated the resolution response to tissue homeostasis by shortening the resolution interval, promoting tissue protection in murine peritonitis, and enhancing survival in polymicrobial sepsis.

Automated summary

In summary, this passage discusses the role of the neuroimmune guidance cue Semaphorin 7A in regulating macrophage metabolism and the resolution of inflammation.