Fig. 4: L-serine in macrophages is related with hyperinflammation and poor prognosis of P. aeruginosa lung infection.

a Total abundance and ¹³C-enrichment of de novo serine and SAM in iAMs after PAO1 or heat-killed PAO1 infection (6 h; U-¹³C-glucose tracer) (n = 5 for total sample, n = 4 for U-¹³C-glucose tracer, n = 1 for ¹²C-glucose negative control, means ± SEMs); b qPCR analysis of Il6 and Il1b mRNA in iAMs treated with different concentrations of L-serine (0, 400, 800,1000 μmol/L, μM) after PAO1 infection (n = 3, means ± SEMs); c Flow cytometry detection of the MFI of CD86⁺ iAMs treated with different concentrations of L-serine (n = 3, means ± SEMs); d Schematic of control and high serine diet-fed mice. Created in BioRender. Chen, R. (2026) https://BioRender.com/ss002xx; e Survival rates of control (10 mg/kg serine) and high-serine diet (50 mg/kg serine)-fed mice after 10⁷ CFU PAO1 infection for 4 days (n = 10, log rank test [Mantel-Cox]); f CFUs of PAO1 in lung tissue (n = 5, means ± SEMs); g Representative images of H&E-stained lung sections and lung damage scores, Scale bar = 100 μm (n = 5, means ± SEMs); h qPCR analysis of Il6 and Il1b mRNA in mouse lung tissue (n = 5, means ± SEMs); i Percentage of the AMs in lung tissue (n = 5, means ± SEMs); j Flow cytometry analysis of the MFI of CD86⁺ macrophages in mouse lung tissue between control and high-serine diet-fed mice after 2 × 10⁶ PAO1 infection (n = 5, means ± SEMs). An unpaired two-sided Student’s t-test was used in (a, f–j); One-way ANOVA followed by Dunnett’s multiple comparison test in (b, c). All experiments are repeated three times independently and similar results are obtained. Source data are provided as a Source Data file.