The crosstalk between PFKFB3 and RSPO2 drives sepsis-induced lung injury by coupling metabolic rewiring to macrophage inflammation.

Aberrantly activated macrophages drive acute lung injury (ALI), but how metabolic reprogramming fuels their dysfunction remains elusive. Here, we investigated PFKFB3, a glycolytic enzyme converting fructose-6-phosphate to fructose-2,6-bisphosphate, in ALI. PFKFB3 was upregulated both in LPS-stimulated macrophages and septic mice, cascading RSPO2 activation. Pharmacological inhibition of PFKFB3 by PFK15 not only mitigated LPS-induced macrophage injury via NF-κB suppression but also protected against ALI in CLP mice. PFK15 effectively blunted PFKFB3-dependent glycolysis and curtailed pro-inflammatory responses by inhibiting RSPO2/β-catenin signaling both in vitro and in vivo. Genetic silencing of PFKFB3 similarly reduced inflammation and suppressed RSPO2/β-catenin signaling. Notably, RSPO2 knockdown ameliorated LPS-induced macrophage dysfunction characterized by hyperglycolysis and excessive inflammation. This protective effect was phenocopied by KYA1797K, an RSPO2/β-catenin inhibitor, which reduced macrophage inflammation and glycolytic activity, thereby alleviating ALI. Collectively, our data support a model wherein a positive feedback loop interconnecting PFKFB3-driven glycolysis and RSPO2 signaling synergizes with the NF-κB pathway to potentiate macrophage inflammation, ultimately exacerbating septic ALI. These findings establish the PFKFB3-RSPO2 circuit as a promising therapeutic target for ALI.