PR001387 (Project)

Description:Background: Nitisinone induced hypertyrosinaemia is well documented in Alkaptonuria (AKU), and there is uncertainty over whether it may contribute to a decline in cognitive function and or mood by altering neurotransmitter metabolism. The aim of this work was to evaluate the impact of nitisinone on the cerebrospinal fluid (CSF) metabolome in a murine model of AKU, with a view to providing additional insight into metabolic changes that occur following treatment with nitisinone. Methods: 17 CSF samples were collected from BALB/c Hgd-/-mice (n=8, treated with nitisinone – 4 mg/L and n=9, no treatment). Samples were diluted 1:1 with deionised water and analysed using a 1290 Infinity II liquid chromatography system coupled to a 6550 quadrupole time-of-flight mass spectrometry (Agilent, Cheadle, UK). Raw data were processed using a targeted feature extraction algorithm and an established in-house accurate mass retention time database. Matched entities (±10 ppm theoretical accurate mass and ±0.3 minutes retention time window) were filtered based on their frequency and variability. Experimental groups were compared using a moderated t-test with Benjamini-Hochberg false-discovery rate adjustment. Results: Tyrosine, acetyl-tyrosine, ?-glutamyl-tyrosine, p-hydroxyphenylacetic acid and 3-(4-hydroxyphenyl)lactic acid were shown to increase in abundance (log2 fold change 2.6-6.9, 3/5 were significant p<0.05) in the mice that received nitisinone. Several other metabolites of interest were matched but no significant differences were observed, including the aromatic amino acids phenylalanine and tryptophan, and monoamine metabolites adrenaline, 3-methoxy-4-hydroxyphenylglycol and octopamine. Conclusions: Evaluation of the CSF metabolome of a murine model of AKU showed a significant difference in the abundance of a limited number of metabolites. None of these have been reported in CSF from a murine model of AKU previously. Moreover this study confirms that some monoamine metabolites do not appear to be altered following nitisinone therapy.