Tryptophan metabolism, its relation to inflammation and stress markers and association with psychological and cognitive functioning: Tasmanian Chronic Kidney Disease pilot study

• DOI: 10.1186/s12882-016-0387-3
• Publication Date: 2016-11-10T11:18:41Z
• Authors: Naama Karu; Charlotte McKercher; David S. Nichols; Noel Davies; Robert A. Shellie; Emily F. Hilder; Matthew D. Jose
• Keywords: Neopterin; Kynurenine pathway

Adults with chronic kidney disease (CKD) exhibit alterations in tryptophan metabolism, mainly via the kynurenine pathway, due to higher enzymatic activity induced by inflammation. Indoles produced gut-microflora are another group of metabolites related inflammation and conditions accompanying CKD. Disruptions metabolism have been associated various neurological psychological disorders. A high proportion CKD patients self-report symptoms depression and/or anxiety decline cognitive functioning. This pilot study examines explores associations Twenty-seven adults were part 49 recruited participate a prospective study, initially an eGFR 15–29 mL/min/1.73 m2. Only participants viable blood samples complete psychological/cognitive data at 2-year follow-up included reported cross-sectional study. Serum analysed Liquid Chromatography coupled Mass Spectrometry, for tryptophan, ten its metabolites, marker neopterin hypothalamic–pituitary–adrenal (HPA) axis cortisol. The breakdown index (kynurenine / tryptophan) correlated (Pearson R = 0.51 P 0.006) but not Neopterin levels also indoxyl sulfate (R 0.68, < 0.0001) 5 range 0.5–0.7, all ≤ 0.01), which negatively (P 0.05). Higher kynurenic acid lower functioning (Spearman −0.39, 0.05), while indole-3 acetic (IAA) was 0.52 0.005, 0.39 0.05, respectively). results this preliminary suggest involvement yet without sparing through 5-HT (serotonin) pathway patients. multiple moderate between measures novel finding. presented necessitate further exploration these within large cohort assess broader significance findings.