Analysis of pulmonary metabolomic homeostasis in pneumocystis pneumonia

<bold>Background:</bold> Pneumocystis Pneumonia (PCP) is a serious respiratory infection primarily affecting individuals with weakened immune systems. However, the pathogenesis of PCP remains poorly understood. <bold>Methods:</bold> We collected bronchoalveolar lavage fluid (BALF) from cohorts of patients with PCP, immunosuppressed patients without PCP (nPCP), and healthy controls (HC). Non-targeted metabolomics analysis was conducted to analyze metabolic signatures. <bold>Results:</bold> Neutrophils were predominant in the BALF of patients with PCP. A total of 475 metabolites were identified, among which lipid compounds were the most abundant. In a comparison between patients with PCP and HC, enrichment analysis of the altered metabolites showed disturbed amino acid metabolism. Caffeine metabolism and phenylalanine tyrosine and tryptophan biosynthesis were the most significantly altered pathways in the PCP group relative to the HC group. Phenylalanine, tyrosine and tryptophan biosynthesis was the most significantly altered pathway in the nPCP group relative to the HC group. Caffeine metabolism was found to be specific in the PCP group. <bold>Conclusions:</bold> In this study, the metabolomic landscape of BALF in patients with PCP was determined. It helps us to understand the pathogenesis of PCP.