Lipidomic and metabolomic profiling reveals novel candidate biomarkers in active systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a challenging disease caused by both genetic and environmental influences. Symptoms of SLE vary and they may come and go, therefore diagnosis and treatment of the disease is difficult. Serum metabolites can not only serve as biomarkers of the disease but also can reveal the pathogenesis. Thus, it is important to find reliable biomarkers for early diagnosis and treatment of the disease, which would greatly benefit SLE patients. Our purpose was to study the metabolite profiles in active systemic lupus erythematosus and to identify metabolites that are significantly altered. Serum samples from 34 participants (17 SLE and 17 healthy) were collected and analyzed. Untargeted lipidomics and metabolomics were used to study the metabolite profiles in serum by high-performance liquid chromatography-tandem mass spectrometry. Serum enzyme-linked immunosorbent assay was performed to validate differentially expressed metabolites. We identified differential expression of over 50 metabolites. These metabolites include several new SLE related metabolite species such as ceramide, trimethylamine N-oxide, xanthine, which were significantly elevated in the serum of active systemic lupus erythematosus patients. Some other metabolites include acylcarnitine, caffeine, hydrocortisone, itaconic acid and serotonin were down-regulated. Our study characterizes the circulating metabolites in active systemic lupus erythematosus and provides several candidate biomarkers for the diagnosis and potential therapeutic targets of the disease.