Juvenile idiopathic arthritis (JIA) represents joint inflammation with an unknown cause that starts before the age of 16, resulting in stiff and painful joints. In addition, JIA patients often report symptoms of sickness behavior. Recent animal studies suggest that proinflammatory cytokines produce sickness behavior by increasing the activity of indoleamine-2,3-dioxygenase (IDO) and guanosinetriphosphate–cyclohydrolase-1 (GTP–CH1). Here, it is hypothesized that inflammation in JIA patients enhances the enzymatic activity of IDO and GTP-CH1 and decreases the co-factor tetrahydrobiopterin (BH4). These compounds play a crucial role in the synthesis and metabolism of neurotransmitters. The aim of our study was to reveal whether inflammation affects both the GTP-CH1 and IDO pathway in JIA patients. Serum samples were collected from twenty-four JIA patients. In these samples, the concentrations of tryptophan (TRP), kynurenine (KYN), tyrosine (TYR), neopterin, and phenylalanine (PHE) were measured. An HPLC method with electrochemical detection was developed to quantify tryptophan, kynurenine, and tyrosine. Neopterin and phenylalanine were quantified by ELISA. The KYN/TRP ratio was measured as an index of IDO activity, while the PHE/TYR ratio was measured as an index of BH4 activity. Neopterin concentrations were used as an indirect measure of GTP-CH1 activity. JIA patients with high disease activity showed higher levels of both neopterin and kynurenine, and a higher ratio of both KYN/TRP and PHE/TYR and lower tryptophan levels than clinically inactive patients. Altogether, these data support our hypothesis that inflammation increases the enzymatic activity of both IDO and GTP-CH1 but decreases the efficacy of the co-factor BH4. In the future, animal studies are needed to investigate whether inflammation-induced changes in these enzymatic pathways and co-factor BH4 lower the levels of the brain neurotransmitters glutamate, noradrenaline, dopamine, serotonin, and melatonin, and consequently, whether they may affect fatigue, cognition, anxiety, and depression. Understanding of these complex neuroimmune interactions provides new possibilities for Pharma-Food interventions to improve the quality of life of patients suffering from chronic inflammation.

Background Internet-based cognitive behavior therapy (I-CBT) for adolescents with chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) has been shown to be effective in a randomized controlled trial (RCT; Fatigue in Teenagers on the Internet [FITNET]). FITNET can cause a significant reduction in fatigue and disability. Objective We aimed to investigate whether FITNET treatment implemented in routine clinical care (IMP-FITNET) was as effective, using the outcomes of the FITNET RCT as the benchmark. Methods Outcomes of CFS/ME adolescents who started IMP-FITNET between October 2012 and March 2018 as part of routine clinical care were compared to the outcomes in the FITNET RCT. The primary outcome was fatigue severity assessed posttreatment. The secondary outcomes were self-reported physical functioning, school attendance, and recovery rates. Clinically relevant deterioration was assessed posttreatment, and for this outcome, a face-to-face CBT trial was used as the benchmark. The attitude of therapists toward the usability of IMP-FITNET was assessed through semistructured interviews. The number of face-to-face consultations during IMP-FITNET was registered. Results Of the 384 referred adolescents with CFS/ME, 244 (63.5%) started IMP-FITNET, 84 (21.9%) started face-to-face CBT, and 56 (14.6%) were not eligible for CBT. Posttreatment scores for fatigue severity (mean 26.0, SD 13.8), physical functioning (mean 88.2, SD 15.0), and full school attendance (mean 84.3, SD 26.5) fell within the 95% CIs of the FITNET RCT. Deterioration of fatigue and physical functioning after IMP-FITNET was observed at rates of 1.2% (n=3) and 4.1% (n=10), respectively, which is comparable to a waiting list condition (fatigue: 1.2% vs 5.7%, χ21=3.5, P=.06; physical functioning: 4.1% vs 11.4%, χ21=3.3, P=.07). Moreover, 41 (16.8%) IMP-FITNET patients made use of face-to-face consultations. Conclusions IMP-FITNET is an effective and safe treatment for adolescents with CFS/ME in routine clinical care.

BackgroundJuvenile idiopathic arthritis (JIA) patients suffer from an inflammatory condition, resulting in painful joints. In addition, JIA patients often report symptoms of sickness behaviour, including depressive symptoms and fatigue. Recent animal studies suggest that proinflammatory cytokines produce sickness behaviour by increasing the activity of indoleamine-2,3-dioxygenase (IDO) and guanosinetriphosphate-cyclohydrolase-1 (GTP-CH1). Here it is hypothesised that inflammation in JIA patients affects the enzymatic activity of IDO and GTP-CH1 and the co-factor BH4. These compounds play a crucial role in the metabolism of the neurotransmitters serotonin and dopamine.ObjectivesThe aim of our study was to reveal whether inflammation affects BH4, IDO and GTP-CH1 (enzymatic) activity in JIA patients.MethodsSerum samples were collected of twenty-four JIA patients. In these samples, the concentrations of tryptophan, kynurenine, tyrosine, neopterin and phenylalanine were measured. An HPLC method with electrochemical detection was developed to quantify tryptophan, kynurenine and tyrosine. Neopterin and phenylalanine were quantified by ELISA. Kyn/trp ratio was measured as an index of IDO activity, while Phen/Tyr ratio was measured as an index of BH4 activity. Neopterin concentrations were used as an indirect measure of GTP-CH1 activity.ResultsJIA patients with high disease activity showed higher levels of both neopterin and kynurenine, and a higher ratio of both Kyn/Trp and Phen/Tyr and lower tryptophan levels than clinically inactive patients.ConclusionsAltogether, these data support our hypothesis that inflammation increases the enzymatic activity of both IDO and GTP-CH1 and decreases the efficacy of the co-factor BH4. Further animal studies are needed to investigate whether inflammation-induced changes in these enzymatic pathways and co-factor lower the levels of the brain neurotransmitters dopamine and serotonin, and consequently produce sickness behaviour and fatigue.AcknowledgementsThis study was financially supported by the focus area ”Future Food Utrecht” of Utrecht University, The Netherlands.Disclosure of InterestNone declared