Phosphoglycerate dehydrogenase-mediated serine reprogramming aggravates macrophage hyperinflammation in murine Pseudomonas aeruginosa pneumonia.

Metabolic reprogramming in immune cells can determine the outcome of pathogen infection. For Pseudomonas aeruginosa, a clinically challenging pathogen, it remains unclear whether the host can exploit this strategy to combat bacterial invasion. Here, we identify phosphoglycerate dehydrogenase as a key mediator of macrophage inflammation during Pseudomonas aeruginosa infection. Pharmacological and genetic inhibition of phosphoglycerate dehydrogenase suppress macrophage hyperactivation and the production of pro-inflammatory cytokines. In a murine model of Pseudomonas aeruginosa pneumonia, myeloid-specific deletion of phosphoglycerate dehydrogenase improves survival, alleviates lung injury, and reduces bacterial load. Similarly, dietary restriction of L-serine improves prognosis in infected mice. Mechanistically, phosphoglycerate dehydrogenase fuels L-serine synthesis to augment one-carbon metabolism, which strengthens the direct interaction between histone H3 lysine 27 trimethylation and dual-specificity phosphatase 4. This cascade ultimately promotes extracellular signal-regulated kinase 1/2 phosphorylation. Our study uncovers a metabolism-epigenetics crosstalk that amplifies macrophage inflammation, proposing metabolic modulation as a therapeutic strategy for bacterial pneumonia.