Tryptophan pathway profiling in multiple sclerosis patients treated with ocrelizumab.

Introduction: L-Tryptophan (Trp) metabolism is impaired across various chronic inflammatory pathologies, including Multiple Sclerosis (MS). Trp processing relies on three metabolic routes, namely Kynurenine, Serotonin and Indole pathways. The host microbiota significantly impacts Trp metabolism, primarily by being responsible for Indole metabolites production and secondarily by shaping both Kynurenine and Serotonin pathways. Pathological conditions and pharmaceutical treatments can elicit changes in microbial populations, leading to alterations in metabolites production and therefore determining rearrangements in host metabolism. Currently, no simultaneous exploration and comparison of all three Trp related metabolic routes has been performed in the context of MS patients before and after Ocrelizumab (OCR) treatment. Methods: By performing mass spectrometry on plasma samples collected from healthy controls and MS patients before and six months after OCR treatment we provided a comparative investigation of Trp metabolomics profile. Results and discussion: Our data points out to concurrent alterations of Trp-related pathways among both OCR treated and untreated MS patients. Furthermore, MS treated patients presented a pattern resembling health state for various metabolites across the pathways. The results reported in our research may contribute to unveiling new perspectives and understanding regarding MS pathogenetic mechanisms.