Fig. 3

Lipid profiles of CAP patients and controls. a Principal component analysis (PCA) scores plot of lipidomic profiles in BALF samples. PCA scores plot colored according to sample group: red circles, severe CAP (SCAP); green circles, non-severe CAP (NSCAP); turquoise four-point stars, healthy control (HC); and yellow triangles, quality control (QC) samples. The PCA model (R2X = 0.871, Q2 = 0.76) reflect good separation trends among SCAP and controls. Classifications based on disease severity (SCAP vs NSCAP, b), age (adult CAP vs elder CAP, c), gender (male CAP vs female CAP, d), and causative pathogens (viral, bacterial, fungal, or mixed infection, e) revealed indistinct separation trends, suggesting that the major clinical-demographic features are not the sole defining features of these BALF lipids