Abstract Rationale We previously identified relationships between the metabolome, infection, and inflammation within the cystic fibrosis (CF) airway and have shown that anaerobic bacteria (e.g., Prevotella) can influence the growth of canonical CF pathogens (i.e., Pseudomonas aeruginosa, Staphylococcus aureus) through mucin fermentation and short-chain fatty acid (SCFA) production. Using metabolomic and sequencing data collected from bronchoalveolar lavage fluid (BALF), we are now testing the hypothesis that SCFAs serve as metabolic biomarkers linking specific microbial taxa to the inflammatory pediatric CF airways. Methods Integrated multi-omic analysis was performed on BALF collected from 195 pediatric patients (N = 142 CF, 53 non-CF) undergoing clinically indicated flexible bronchoscopy. Lung function (FEV1% Predicted, FVC% Predicted, FEV1/FVC) and BALF white blood cell (WBC) counts were recorded. Targeted quantification of eight SCFAs (2-methylbutyric, Acetic, Butyric, Hexanoic, Isobutyric, Isovaleric, Propionic, and Valeric acids) and global metabolomic profiling were done via liquid chromatography dual mass spectrometry (Metabolon Inc.). 16S rRNA gene sequencing determined relative abundance (RA) of key anaerobes (Fusobacterium, Prevotella, Streptococcus, Veillonella spp.) and two CF pathogens (Pseudomonas, Staphylococcus). Analyses included Wilcoxon rank-sum tests with Bonferroni correction, Spearman’s rank correlations (ρ), and Principal Component Analysis (PCA). Results In BALF, SCFA concentrations were comparable between groups, though hexanoic acid was greater in CF (p 0.001). WBC counts were higher in CF BALF (p = 0.023) and positively associated with total SCFA concentration (ρ = 0.75, p = 0.025) and all branched-chain SCFAs (BCSCFA: Isovaleric, Isobutyric, 2-methylbutyric; ρ ≤ 0.75, p 0.04). BCSCFA levels correlated with non-SCFA metabolites i.e., amino acids (AA) and lactate (ρ ≤ 0.47, p 0.001) and Staphylococcus RA (ρ = 0.46, p 0.001). Prevotella and Streptococcus RA negatively correlated with butyric acid concentrations (ρ=-0.25, p 0.03). In CF samples, two SCFA concentrations (Butyric, Hexanoic) and total AA abundance inversely correlated with lung function FEV1% Predicted (ρ≤-0.37), FVC% Predicted (ρ≤-0.31), FEV1/FVC (ρ≤-0.30), p 0.04. PCA revealed distinct metabolic heterogeneity among CF samples, with PC1 and PC2 explaining 61.14% of variance. Conclusions SCFA concentrations may reflect dynamic interactions between microbial community composition, inflammation, and proteolytic metabolism in the CF airway. Elevated BCSCFA levels strongly associated with Staphylococcus abundance and inflammatory markers, identifying them as potential biomarkers of airway injury. Prevotella- and Streptococcus-dominated communities may consume or suppress SCFA production, disrupting protective metabolic balance. SCFA metabolism may actively contribute to the development of early CF lung disease, as Staphylococcus often initially colonizes pediatric CF airways. Our ongoing analyses will further integrate clinical, microbial, and inflammatory markers with metabolomic data to investigate associations and identify mechanistic insights for future study. This abstract is funded by: NIH R01HL136499
Fought et al. (Fri,) studied this question.