Metabolomics connects aberrant bioenergetic, transmethylation, and gut microbiota in sarcoidosis

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Granulomatous inflammation in sarcoidosis may affect multiple organs, including the lungs, skin, CNS, and the eyes, leading to severe morbidity and mortality. The underlying mechanisms for sustained inflammation in sarcoidosis are unknown. We hypothesized that metabolic changes play a critical role in perpetuation of inflammation in sarcoidosis. ¹H nuclear magnetic resonance (NMR)-based untargeted metabolomic analysis was used to identify circulating molecules in serum to discriminate sarcoidosis patients from healthy controls. Principal component analyses (PCA) were performed to identify different metabolic markers and explore the changes of associated biochemical pathways. Using Chenomx 7.6 NMR Suite software, we identified and quantified metabolites responsible for such separation in the PCA models. Quantitative analysis showed that the levels of metabolites, such as 3-hydroxybutyrate, acetoacetate, carnitine, cystine, homocysteine, pyruvate, and trimethylamine N-oxide were significantly increased in sarcoidosis patients. Interestingly, succinate, a major intermediate metabolite involved in the tricyclic acid cycle was significantly decreased in sarcoidosis patients. Application of integrative pathway analyses identified deregulation of butanoate, ketone bodies, citric cycle metabolisms, and transmethylation. This may be used for development of new drugs or nutritional modification.