Longitudinal associations of plasma kynurenines and ratios with fatigue and quality of life in colorectal cancer survivors up to 12 months post-treatment.

Fatigue is prevalent in colorectal cancer (CRC) survivors, impacting their health-related quality of life (HRQoL). Inflammation-induced activation of the kynurenine pathway may play a role in cancer-related fatigue and HRQoL, but evidence is scarce. Therefore, we aimed to investigate longitudinal associations of plasma tryptophan, kynurenines, and ratios with fatigue and HRQoL in CRC survivors up to 12 months post-treatment. Repeated measurements at 6 weeks, 6 months, and 12 months post-treatment were performed in 249 stage I-III CRC survivors. Plasma tryptophan and eight kynurenines were analyzed using liquid chromatography-tandem mass spectrometry (LC/MS-MS). Fatigue and HRQoL outcomes were evaluated using validated questionnaires. Confounder-adjusted linear mixed models were conducted to analyze longitudinal associations, with false discovery rate (FDR) correction. Higher tryptophan (Trp), kynurenic acid (KA), and xanthurenic acid (XA) concentrations, as well as a higher kynurenic acid-to-quinolinic acid ratio (KA/QA), were associated with less fatigue and better functioning, while a higher kynurenine-to-tryptophan ratio (KTR) and 3-hydroxykynurenine ratio (HKr) were associated with more fatigue and worse functioning. Finally, higher KA and XA concentrations and a higher KA/QA ratio were associated with a higher overall HRQoL summary score, while a higher HKr was associated with a lower overall HRQoL summary score. In conclusion, we observed that tryptophan and several kynurenines were longitudinally associated with fatigue and HRQoL in CRC survivors up to 12 months post-treatment. Future research is needed to validate our findings and explore the potential of the kynurenine pathway as intervention target for reducing fatigue and enhancing HRQoL after CRC treatment.

Neopterin, kynurenine metabolites, and indexes related to vitamin B6 are associated with post-stroke cognitive impairment: The Nor-COAST study.

BACKGROUND AND AIMS: We have previously shown that systemic inflammation was associated with post-stroke cognitive impairment (PSCI). Because neopterin, kynurenine pathway (KP) metabolites, and B6 vitamers are linked to inflammation, in our study we investigated whether those biomarkers were associated with PSCI. MATERIAL AND METHODS: The Norwegian Cognitive Impairment After Stroke study is a prospective multicenter cohort study of patients with acute stroke recruited from May 2015 through March 2017. Plasma samples of 422 participants (59 % male) with ischemic stroke from the index hospital stay and 3 months post-stroke were available for analyses of neopterin, KP metabolites, and B6 vitamers using liquid chromatography-tandem mass spectrometry. Mixed linear regression analyses adjusted for age, sex, and creatinine, were used to assess whether there were associations between those biomarkers and cognitive outcomes, measured by the Montreal Cognitive Assessment scale (MoCA) at 3-, 18-, and 36-month follow-up. RESULTS: Participants had a mean (SD) age of 72 (12) years, with a mean (SD) National Institutes of HealthStroke Scale score of 2.7 (3.6) at Day 1. Higher baseline values of quinolinic acid, PAr (i.e., an inflammatory marker based on vitamin B6 metabolites), and HKr (i.e., a marker of functional vitamin B6 status based on selected KP metabolites) were associated with lower MoCA score at 3, 18, and 36 months post-stroke (p < 0.01). Higher baseline concentrations of neopterin and 3-hydroxykynurenine were associated with lower MoCA scores at 18 and 36 months, and higher concentrations of xanthurenic acid were associated with higher MoCA score at 36 months (p < 0.01). At 3 months post-stroke, higher concentrations of neopterin and lower values of pyridoxal 5́-phosphate were associated with lower MoCA scores at 18- and 36-month follow-up, while lower concentrations of picolinic acid were associated with a lower MoCA score at 36 months (p < 0.01). CONCLUSION: Biomarkers and metabolites of systemic inflammation, including biomarkers of cellular immune activation, indexes of vitamin B6 homeostasis, and several neuroactive metabolites of the KP pathway, were associated with PSCI. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02650531.

Influence of cardiorespiratory fitness on obesity-associated inflammation in women and men: The FATCOR study.

BACKGROUND AND AIMS: Cardiorespiratory fitness has been postulated to lower chronic inflammation in obesity. We assessed sex-specific associations of inflammation with cardiorespiratory fitness in overweight and obese persons. METHODS AND RESULTS: Peak oxygen uptake (VO2max) was measured by treadmill in 566 participants (age 48 ± 9 years, 60% women) with body mass index >27.0 kg/m2 in the FAT associated CardiOvasculaR dysfunction (FATCOR) study. Fitness was identified from age- and sex specific reference levels of VO2max. The inflammatory markers C-reactive protein (CRP), serum amyloid A (SAA), kynurenine:tryptophan ratio (KTR) and pyriodoxic acid ratio (PAr) were measured by mass spectrometry. In the total study population 63% had obesity and 74% were cardiorespiratory unfit. Unfit women had the highest fat percentage and the highest serum levels of CRP and SAA (p < 0.05). In multivariable linear regression analyses in women, higher CRP (ß -0.15, p = 0.001), SAA (ß -0.10, p = 0.03) and PAr (ß -0.09, p = 0.03) were associated with lower VO2max after adjusting for confounders. In multivariable analyses in men, higher PAr (ß -0.14, p = 0.02) was associated with lower VO2max. In multivariable analyses in obese women, higher CRP and PAr remained associated with lower VO2max (p < 0.05), while in obese men there was no significant association. When normalizing VO2max for fat-free mass (VO2maxFFM) higher CRP, SAA and PAr index were associated with lower VO2maxFFM in women, while only higher PAr index was associated with lower VO2maxFFM in men. CONCLUSION: The association of inflammation with lower cardiorespiratory fitness was more pronounced in women than men, in particular when obesity was present. CLINICAL TRIAL REGISTRATION: URL: http://www. CLINICALTRIALS: gov NCT02805478.

Clinical and biochemical impact of vitamin B6 deficiency in primary sclerosing cholangitis before and after liver transplantation.

BACKGROUND AND AIMS: We previously demonstrated that people with primary sclerosing cholangitis (PSC) had reduced gut microbial capacity to produce active vitamin B6 (pyridoxal 5'-phosphate [PLP]), which corresponded to lower circulating PLP levels and poor outcomes. Here, we define the extent and biochemical and clinical impact of vitamin B6 deficiency in people with PSC from several centers before and after liver transplantation (LT). METHODS: We used targeted liquid chromatography-tandem mass spectrometry to measure B6 vitamers and B6-related metabolic changes in blood from geographically distinct cross-sectional cohorts totaling 373 people with PSC and 100 healthy controls to expand on our earlier findings. Furthermore, we included a longitudinal PSC cohort (n = 158) sampled prior to and serially after LT, and cohorts of people with inflammatory bowel disease (IBD) without PSC (n = 51) or with primary biliary cholangitis (PBC) (n = 100), as disease controls. We used Cox regression to measure the added value of PLP to predict outcomes before and after LT. RESULTS: In different cohorts, 17-38% of people with PSC had PLP levels below the biochemical definition of a vitamin B6 deficiency. The deficiency was more pronounced in PSC than in IBD without PSC and PBC. Reduced PLP was associated with dysregulation of PLP-dependent pathways. The low B6 status largely persisted after LT. Low PLP independently predicted reduced LT-free survival in both non-transplanted people with PSC and in transplant recipients with recurrent disease. CONCLUSIONS: Low vitamin B6 status with associated metabolic dysregulation is a persistent feature of PSC. PLP was a strong prognostic biomarker for LT-free survival both in PSC and recurrent disease. Our findings suggest that vitamin B6 deficiency modifies the disease and provides a rationale for assessing B6 status and testing supplementation. IMPACT AND IMPLICATIONS: We previously found that people with PSC had reduced gut microbial potential to produce essential nutrients. Across several cohorts, we find that the majority of people with PSC are either vitamin B6 deficient or have a marginal deficiency, which remains prevalent even after liver transplantation. Low vitamin B6 levels strongly associate with reduced liver transplantation-free survival as well as deficits in biochemical pathways dependent on vitamin B6, suggesting that the deficiency has a clinical impact on the disease. The results provide a rationale for measuring vitamin B6 and to investigate whether vitamin B6 supplementation or modification of the gut microbial community can help improve outcomes for people with PSC.

Plasma methylmalonic acid predicts risk of acute myocardial infarction and mortality in patients with coronary heart disease: A prospective 2-cohort study.

BACKGROUND: Elevated plasma methylmalonic acid (MMA) is reported in patients with established coronary heart disease (CHD) and is considered a marker of vitamin B12 deficiency. Moreover, MMA-dependent reactions have been linked to alterations in mitochondrial energy metabolism and oxidative stress, key features in the pathophysiology of cardiovascular diseases (CVDs). OBJECTIVES: We examined whether plasma MMA prospectively predicted the long-term risk of acute myocardial infarction (AMI) and mortality. METHODS AND RESULTS: Using Cox modeling, we estimated hazard ratios (HRs) for endpoints according to per 1-SD increment of log-transformed plasma MMA in two independent populations: the Western Norway Coronary Angiography Cohort (WECAC) (patients evaluated for CHD; n = 4137) and the Norwegian Vitamin Trial (NORVIT) (patients hospitalized with AMI; n = 3525). In WECAC and NORVIT, 12.8% and 18.0% experienced an AMI, whereas 21.8% and 19.9% died, of whom 45.5% and 60.3% from CVD-related causes during follow-up (range 3-11 years), respectively. In WECAC, age- and gender-adjusted HRs (95% confidence interval) were 1.18 (1.09-1.28), 1.25 (1.18-1.33), and 1.28 (1.17-1.40) for future AMI, total mortality, and CVD mortality, respectively. Corresponding risk estimates were 1.19 (1.10-1.28), 1.22 (1.14-1.31), and 1.30 (1.19-1.42) in NORVIT. These estimates were only slightly attenuated after multivariable adjustments. Across both cohorts, the MMA-risk association was stronger in older adults, women, and non-smokers. CONCLUSIONS: Elevated MMA was associated with an increased risk of AMI and mortality in patients with suspected or verified CHD.

Correlations between kynurenines in plasma and CSF, and their relation to markers of Alzheimer's disease pathology.

INTRODUCTION: Altered levels of kynurenines in blood and cerebrospinal fluid (CSF) have been reported in Alzheimer's disease (AD). However, it is still largely unknown whether peripheral kynurenine concentrations resemble those found in CSF and how they relate to AD pathology. We therefore studied correlations between kynurenines in plasma and CSF and their associations with CSF amyloid-beta (Aß1-42) and tau levels in patients from the memory clinic spanning the whole cognitive spectrum. METHODS: The Biobank Alzheimer Center Limburg study is a prospective cohort study of consecutive patients referred to the memory clinic of the Alzheimer Center Limburg. Plasma and CSF concentrations of tryptophan (TRP), eight kynurenines and neopterin from 138 patients were determined by means of LC-MS/MS. Additionally, CSF Aß1-42, total-tau (t-tau) and phosphorylated tau (p-tau) concentrations were determined using commercially available single-parameter ELISA methods. Partial correlations were used to analyze cross-sectional associations between kynurenines in plasma and CSF and their relation to AD related CSF-biomarkers adjusted for age, sex, educational level, and kidney function. RESULTS: Moderate to strong correlations were observed between plasma and CSF levels for quinolinic acid (QA; r = 0.63), TRP (r = 0.47), anthranilic acid (r = 0.59), picolinic acid (r = 0.55), and the kynurenine (KYN)/TRP ratio (KTR; r = 0.55; all p < 0.0001), while other kynurenines correlated only weakly with their corresponding CSF values. No correlations were found between plasma and CSF levels of KA/QA. Several kynurenines were also weakly correlated with Aß1-42, t-tau or p-tau. Plasma levels of KA/QA were negatively correlated with Aß1-42 (r = -0.21, p < 0.05). Plasma levels of TRP were negatively correlated with t-tau (r = -0.19) and levels of KYN with p-tau (r = -0.18; both p < 0.05). CSF levels of KYN (r = 0.20, p < 0.05), KA (r = 0.23, p < 0.01), and KTR (r = 0.18, p < 0.05) were positively correlated with Aß1-42. Finally, TRP and KYN were negatively (r = -0.22 and r = -0.18, respectively), and neopterin positively (r = 0.19) correlated with p-tau (all p < 0.05). CONCLUSIONS: Plasma concentrations of TRP, KP metabolites, KTR, and neopterin all significantly correlated positively with their corresponding CSF concentrations, but many correlations were weak. Additionally, our results suggest a relation between higher kynurenine levels and lower AD pathology load. These results need verification in future studies and require more research into (shared) underlying mechanisms.

Assessment of vitamin B6 status in never-pregnant, pregnant and postpartum women and their infants.

PURPOSE: Pyridoxal 5´-phosphate (PLP) is the main form of vitamin B6 in humans and functions a coenzyme for more than 160 different enzymatic reactions. The purpose of the study was to find plasma PLP concentrations, which ensure an optimal vitamin B6 status determined by a metabolic marker, in never-pregnant, pregnant and lactating women and their infants. METHODS: In an observational, prospective study, plasma PLP and the metabolic marker, HKr (hydroxykynurenine/(kynurenic acid + anthranilic acid + xanthurenic acid + hydroxyanthranilic acid) were assessed in women (n = 114) from pregnancy week 18 to 6 months postpartum and related to infant status. Never-pregnant women 18-40 years (n = 127) were included as controls. RESULTS: Compared to controls, plasma PLP decreased during pregnancy and increased postpartum, while HKr increased from week 18 to 6 weeks postpartum, indicating maternal vitamin B6 insufficiency during this period. In never-pregnant women, HKr increased gradually with plasma PLP < 100 nmol/L, and in pregnancy week 28 a sharp increase in HKr was seen at plasma PLP < 30 nmol/L. Despite correcting for maternal vitamin B6 status, infant median plasma PLP decreased with months of exclusive breastfeeding. CONCLUSIONS: Plasma PLP and kynurenine concentrations differ substantially between never-pregnant, pregnant and postpartum women and infants. A plasma PLP concentration in the range of 50-100 nmol/L seems to ensure an optimal vitamin B6 status for never-pregnant women, whereas a plasma PLP > 30 nmol/L in pregnancy week 28 ensures an adequate vitamin B6 status during pregnancy and lactation. Infant vitamin B6 status at age 6 months is inversely correlated to number of months of exclusive breastfeeding.

Exploratory analyses on the effect of time since last meal on concentrations of amino acids, lipids, one-carbon metabolites, and vitamins in the Hordaland Health Study.

PURPOSE: Dietary intake may have pronounced effects on circulating biomarker concentrations. Therefore, the aim was to provide a descriptive overview of serum metabolite concentrations in relation to time since last meal, focusing on amino acids, lipids, one-carbon metabolites, and biomarkers of vitamin status. METHODS: We used baseline data from the observational community-based Hordaland Health Study, including 2960 participants aged 46-49 years and 2874 participants aged 70-74 years. A single blood draw was taken from each participant, and time since last meal varied. Estimated marginal geometric mean metabolite concentrations were plotted as a function of time since last meal, up to 7 h, adjusted for age, sex, and BMI. RESULTS: We observed a common pattern for nearly all amino acids and one-carbon metabolites with highest concentrations during the first 3 h after dietary intake. Homocysteine and cysteine were lowest the 1st hour after a meal, while no patterns were observed for glutamate and glutamic acid. The concentrations of phylloquinone and triglycerides were highest 1 h after dietary intake. Thiamine and thiamine monophosphate concentrations were highest, while flavin mononucleotide concentrations were lowest within the first 2 h after a meal. No clear patterns emerged for the other fat-soluble vitamins, blood lipids, or B-vitamin biomarkers. CONCLUSION: Our findings suggest that distinguishing between "fasting" and "non-fasting" blood samples may be inadequate, and a more granular approach is warranted. This may have implications for how to account for dietary intake when blood sampling in both clinical and research settings.

A diet containing cod backbone proteins attenuated the development of mesangial sclerosis and tubular dysfunction in male obese BTBR ob/ob mice.

PURPOSE: The obese black and tan, brachyuric (BTBR) ob/ob mouse spontaneously develops features comparable to human diabetic nephropathy. The primary aim of the present study was to investigate if a diet containing fish proteins would attenuate or delay the development of glomerular hypertrophy (glomerulomegaly), mesangial sclerosis and albuminuria in obese BTBR ob/ob mice. METHODS: Obese BTBR.CgLepob/WiscJ male mice were fed diets containing 25% of protein from Atlantic cod backbones and 75% of protein from casein (Cod-BB group), or casein as the sole protein source (control group). Kidneys were analysed morphologically, and markers for renal dysfunction were analysed biochemically in urine and serum. RESULTS: The Cod-BB diet attenuated the development of mesangial sclerosis (P 0.040) without affecting the development of glomerular hypertrophy and albuminuria. The urine concentration of cystatin C (relative to creatinine) was lower in mice fed the Cod-BB diet (P 0.0044). CONCLUSION: A diet containing cod backbone protein powder attenuated the development of mesangial sclerosis and tubular dysfunction in obese BTBR ob/ob mice, but did not prevent the development of glomerular hypertrophy and albuminuria in these mice.

Higher concentrations of kynurenic acid in CSF are associated with the slower clinical progression of Alzheimer's disease.

INTRODUCTION: The kynurenine pathway's (KP) malfunction is closely related to Alzheimer's disease (AD), for antagonistic kynurenic acid (KA) and agonistic quinolinic acid act on the N-methyl-D-aspartate receptor, a possible therapeutic target in treating AD. METHODS: In our longitudinal case-control study, KP metabolites in the cerebrospinal fluid were analyzed in 311 patients with AD and 105 cognitively unimpaired controls. RESULTS: Patients with AD exhibited higher concentrations of KA (ß = 0.18, P < 0.01) and picolinic acid (ß = 0.20, P < 0.01) than the controls. KA was positively associated with tau pathology (ß = 0.29, P < 0.01), and a higher concentration of KA was associated with the slower progression of dementia. DISCUSSION: The higher concentrations of neuroprotective metabolites KA and picolinic acid suggest that the activation of the KP's neuroprotective branch is an adaptive response in AD and may be a promising target for intervention and treatment. Highlights Patients with Alzheimer's disease (AD) exhibited higher concentrations of kynurenic acid and picolinic acid than controls. Higher concentrations of kynurenic acid were associated with slower progression of AD. Potential neurotoxic kynurenines were not increased among patients with AD. Activation of the kynurenine pathway's neuroprotective branch may be an adaptive response in AD.

Biomarkers of the transsulfuration pathway and risk of renal cell carcinoma in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

Previous studies have suggested that components of one-carbon metabolism, particularly circulating vitamin B6, have an etiological role in renal cell carcinoma (RCC). Vitamin B6 is a cofactor in the transsulfuration pathway. We sought to holistically investigate the role of the transsulfuration pathway in RCC risk. We conducted a nested case-control study (455 RCC cases and 455 matched controls) within the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Plasma samples from the baseline visit were analyzed for metabolites of the transsulfuration pathway, including pyridoxal 5'-phosphate (PLP, the biologically active form of vitamin B6), homocysteine, serine, cystathionine, and cysteine, in addition to folate. Bayesian conditional logistic regression was used to estimate associations of metabolites with RCC risk as well as interactions with established RCC risk factors. Circulating PLP and cysteine were inversely associated with RCC risk, and these associations were not attenuated after adjustment for other transsulfuration metabolites (odds ratio (OR) and 90% credible interval (CrI) per 1 SD increase in log concentration: 0.76 [0.66, 0.87]; 0.81 [0.66, 0.96], respectively). A comparison of joint metabolite profiles suggested substantially greater RCC risk for the profile representative of low overall transsulfuration function compared to high function (OR 2.70 [90% CrI 1.26, 5.70]). We found some statistical evidence of interactions of cysteine with body mass index, and PLP and homocysteine with smoking status, on their associations with RCC risk. In conclusion, we found evidence suggesting that the transsulfuration pathway may play a role in metabolic dysregulation leading to RCC development.

Consumption of a light meal affects serum concentrations of one-carbon metabolites and B-vitamins. A clinical intervention study.

The transfer of one-carbon units between molecules in metabolic pathways is essential for maintaining cellular homeostasis, but little is known about whether the circulating concentrations of metabolites involved in the one-carbon metabolism are affected by the prandial status. Epidemiological studies do not always consistently use fasting or non-fasting blood samples or may lack information on the prandial status of the study participants. Therefore, the main aim of the present study was to investigate the effects of a light breakfast on serum concentrations of selected metabolites and B-vitamins related to the one-carbon metabolism; i.e. the methionine-homocysteine cycle, the folate cycle, the choline oxidation pathway and the transsulfuration pathway. Sixty-three healthy adults (thirty-six women) with BMI ≥ 27 kg/m2 were included in the study. Blood was collected in the fasting state and 60 and 120 min after intake of a standardised breakfast consisting of white bread, margarine, white cheese, strawberry jam and orange juice (2218 kJ). The meal contained low amounts of choline, betaine, serine and vitamins B2, B3, B6, B9 and B12. Serum concentrations of total homocysteine, total cysteine, flavin mononucleotide, nicotinamide and pyridoxal 5'-phosphate were significantly decreased, and concentrations of choline, betaine, dimethylglycine, sarcosine, cystathionine and folate were significantly increased following breakfast intake (P < 0·05). Our findings demonstrate that the intake of a light breakfast with low nutrient content affected serum concentrations of several metabolites and B-vitamins related to the one-carbon metabolism.

Quantifying Precision Loss in Targeted Metabolomics Based on Mass Spectrometry and Nonmatching Internal Standards.

In mass spectrometry, reliable quantification requires correction for variations in ionization efficiency between samples. The preferred method is the addition of a stable isotope-labeled internal standard (SIL-IS). In targeted metabolomics, a dedicated SIL-IS for each metabolite of interest may not always be realized due to high cost or limited availability. We recently completed the analysis of more than 70 biomarkers, each with a matching SIL-IS, across four mass spectrometry-based platforms (one GC-MS/MS and three LC-MS/MS). Using data from calibrator and quality control samples added to 60 96-well trays (analytical runs), we calculated analytical precision (CV) retrospectively. The use of integrated peak areas for all metabolites and internal standards allowed us to calculate precision for all matching analyte (A)/SIL-IS (IS) pairs as well as for all nonmatching A/IS pairs within each platform (total n = 1442). The median between-run precision for matching A/IS across the four platforms was 2.7-5.9%. The median CV for nonmatching A/IS (corresponding to pairing analytes with a non-SIL-IS) was 2.9-10.7 percentage points higher. Across all platforms, CVs for nonmatching A/IS increased with increasing difference in retention time (Spearman's rho of 0.17-0.93). The CV difference for nonmatching vs matching A/IS was often, but not always, smaller when analytes and internal standards were close structural analogs.

Inflammation-Related Marker Profiling of Dietary Patterns and All-cause Mortality in the Melbourne Collaborative Cohort Study.

BACKGROUND: Nutritional epidemiology research using self-reported dietary intake is prone to measurement error. Objective methods are being explored to overcome this limitation. OBJECTIVES: We aimed to examine 1) the association between plasma markers related to inflammation and derive marker scores for dietary patterns [Mediterranean dietary score (MDS), energy-adjusted Dietary Inflammatory Index (E-DIITM), Alternative Healthy Eating Index 2010 (AHEI)] and 2) the associations of these marker scores with mortality. METHODS: Weighted marker scores were derived from the cross-sectional association between 30 plasma markers and each dietary score (assessed using food-frequency questionnaires) using linear regression for 770 participants in the Melbourne Collaborative Cohort Study (aged 50-82 y). Prospective associations between marker scores and mortality (n = 249 deaths) were assessed using Cox regression (median follow-up: 14.4 y). RESULTS: The MDS, E-DII, and AHEI were associated (P < 0.05) with 9, 14, and 11 plasma markers, respectively. Healthier diets (higher MDS and AHEI, and lower anti-inflammatory, E-DII) were associated with lower concentrations of kynurenines, neopterin, IFN-γ, cytokines, and C-reactive protein. Five of 6 markers common to the 3 dietary scores were components of the kynurenine pathway. The 3 dietary-based marker scores were highly correlated (Spearman ρ: -0.74, -0.82, and 0.93). Inverse associations (for 1-SD increment) were observed with all-cause mortality for the MDS marker score (HR: 0.84; 95% CI: 0.72-0.98) and the AHEI marker score (HR: 0.76; 95% CI: 0.66-0.89), whereas a positive association was observed with the E-DII marker score (HR: 1.18; 95% CI: 1.01-1.39). The same magnitude of effect was not observed for the respective dietary patterns. CONCLUSIONS: Markers involved in inflammation-related processes are associated with dietary quality, including a substantial overlap between markers associated with the MDS, the E-DII, and the AHEI, especially kynurenines. Unfavorable marker scores, reflecting poorer-quality diets, were associated with increased mortality.

Investigating novel biomarkers of immune activation and modulation in the context of sedentary behaviour: a multicentre prospective ischemic stroke cohort study.

BACKGROUND: Sedentary behaviour is associated with disease, but the molecular mechanisms are not understood. Valid biomarkers with predictive and explanatory properties are required. Therefore, we have investigated traditional and novel biomarkers of inflammation and immune modulation and their association to objectively measured sedentary behaviour in an ischemic stroke population. METHODS: Patients admitted to hospital with acute ischemic stroke were included in the multicentre Norwegian Cognitive Impairment After Stroke (Nor-COAST) study (n = 815). For this sub-study (n = 257), sedentary behaviour was registered 3 months after stroke using position transition data from the body-worn sensor, ActivPal®. Blood samples were analysed for high sensitive C-reactive protein (hsCRP), the cytokines interleukin-6 (IL-6) and 10 (IL-10), neopterin, tryptophan (Trp), kynurenine (kyn), kynurenic acid (KA), and three B6 vitamers, pyridoxal 5'-phosphate (PLP), pyridoxal (PL), and pyridoxic acid (PA). The kynurenine/tryptophan ratio (KTR) and the pyridoxic acid ratio index (PAr = PA: PL + PLP) were calculated. RESULTS: Of the 815 patients included in the main study, 700 attended the three-month follow-up, and 257 fulfilled the inclusion criteria for this study. Sedentary time was significantly associated with levels of hsCRP, IL-6, neopterin, PAr-index, and KA adjusted for age, sex, waist circumference, and creatinine. In a fully adjusted model including all the significant biomarkers except hsCRP (because of missing values), sedentary time was independently positively associated with the PAr-index and negatively with KA. We did not find an association between sedentary behaviour, IL-10, and KTR. CONCLUSIONS: The PAr-index is known to capture several modes of inflammation and has previously shown predictive abilities for future stroke. This novel result indicates that the PAr-index could be a useful biomarker in future studies on sedentary behaviour and disease progression. KA is an important modulator of inflammation, and this finding opens new and exciting pathways to understand the hazards of sedentary behaviour. TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov ( NCT02650531 ). First posted 08/01/2016.

Neopterin and kynurenic acid as predictors of stroke recurrence and mortality: a multicentre prospective cohort study on biomarkers of inflammation measured three months after ischemic stroke.

BACKGROUND: Chronic low-grade inflammation is associated with both ischemic stroke and sedentary behaviour. The aim of this study was to investigate the predictive abilities of biomarkers of inflammation and immune modulation associated with sedentary behaviour for ischemic stroke recurrence and mortality in a stroke population. METHODS: Patients admitted to hospital for acute stroke were recruited to the prospective multicentre cohort study, the Norwegian Cognitive Impairment After Stroke (Nor-COAST) study, from May 2015 until March 2017. Patients with ischemic stroke, blood samples available from the three-month follow-up, and no stroke recurrence before the three-month follow-up were included. Serum was analysed for C-reactive protein (CRP) with high-sensitive technique, and plasma for interleukin-6 (IL-6), neopterin, pyridoxic acid ratio index (PAr-index: 4-pyridoxic acid: [pyrioxal+pyridoxal-5'-phosphate]) and kynurenic acid (KA). Ischemic stroke recurrence and death were identified by the Norwegian Stroke Registry and the Cause of Death Registry until 31 December 2018. RESULTS: The study included 354 patients, 57% male, mean age 73 (SD 11) years, mean observation time 2.5 (SD 0.6) years, and median National Institute of Health Stroke Scale of 0 (IQR 1) at three months. CRP was associated with mortality (HR 1.40, CI 1.01, 1.96, p = 0.046), and neopterin was associated with the combined endpoint (recurrent ischemic stroke or death) (HR 1.52, CI 1.06, 2.20, p = 0.023), adjusted for age, sex, prior cerebrovascular disease, modified Rankin Scale, and creatinine. When adding neopterin and KA to the same model, KA was negatively associated (HR 0.57, CI 0.33, 0.97, p = 0.038), and neopterin was positively associated (HR 1.61, CI 1.02, 2.54, p = 0.040) with mortality. Patients with cardioembolic stroke at baseline had higher levels of inflammation at three months. CONCLUSION: Neopterin might be a valuable prognostic biomarker in stroke patients. The use of KA as a measure of anti-inflammatory capacity should be investigated further. TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov ( NCT02650531 ). First posted on 08/01/2016.

A prospective evaluation of serum methionine-related metabolites in relation to pancreatic cancer risk in two prospective cohort studies.

Deficiencies in methyl donor status may render DNA methylation changes and DNA damage, leading to carcinogenesis. Epidemiological studies reported that higher dietary intake of choline is associated with lower risk of pancreatic cancer, but no study has examined the association of serum choline and its metabolites with risk of pancreatic cancer. Two parallel case-control studies, one nested within the Shanghai Cohort Study (129 cases and 258 controls) and the other within the Singapore Chinese Health Study (58 cases and 104 controls), were conducted to evaluate the associations of baseline serum concentrations of choline, betaine, methionine, total methyl donors (i.e., sum of choline, betaine and methionine), dimethylglycine and trimethylamine N-oxide (TMAO) with pancreatic cancer risk. In the Shanghai cohort, odds ratios and 95% confidence intervals of pancreatic cancer for the highest quartile of choline, betaine, methionine, total methyl donors and TMAO were 0.27 (0.11-0.69), 0.57 (0.31-1.05), 0.50 (0.26-0.96), 0.37 (0.19-0.73) and 2.81 (1.37-5.76), respectively, compared to the lowest quartile. The corresponding figures in the Singapore cohort were 0.85 (0.23-3.17), 0.50 (0.17-1.45), 0.17 (0.04-0.68), 0.33 (0.10-1.16) and 1.42 (0.50-4.04). The inverse associations of methionine and total methyl donors including choline, betaine and methionine with pancreatic cancer risk in both cohorts support that DNA repair and methylation play an important role against the development of pancreatic cancer. In the Shanghai cohort, TMAO, a gut microbiota-derived metabolite of dietary phosphatidylcholine, may contribute to higher risk of pancreatic cancer, suggesting a modifying role of gut microbiota in the dietary choline-pancreatic cancer risk association.

Plasma metabolites associated with colorectal cancer stage: Findings from an international consortium.

Colorectal cancer is the second most common cause of cancer-related death globally, with marked differences in prognosis by disease stage at diagnosis. We studied circulating metabolites in relation to disease stage to improve the understanding of metabolic pathways related to colorectal cancer progression. We investigated plasma concentrations of 130 metabolites among 744 Stages I-IV colorectal cancer patients from ongoing cohort studies. Plasma samples, collected at diagnosis, were analyzed with liquid chromatography-mass spectrometry using the Biocrates AbsoluteIDQ™ p180 kit. We assessed associations between metabolite concentrations and stage using multinomial and multivariable logistic regression models. Analyses were adjusted for potential confounders as well as multiple testing using false discovery rate (FDR) correction. Patients presented with 23, 28, 39 and 10% of Stages I-IV disease, respectively. Concentrations of sphingomyelin C26:0 were lower in Stage III patients compared to Stage I patients (pFDR < 0.05). Concentrations of sphingomyelin C18:0 and phosphatidylcholine (diacyl) C32:0 were statistically significantly higher, while citrulline, histidine, phosphatidylcholine (diacyl) C34:4, phosphatidylcholine (acyl-alkyl) C40:1 and lysophosphatidylcholines (acyl) C16:0 and C17:0 concentrations were lower in Stage IV compared to Stage I patients (pFDR < 0.05). Our results suggest that metabolic pathways involving among others citrulline and histidine, implicated previously in colorectal cancer development, may also be linked to colorectal cancer progression.

Five salmon dinners per week were not sufficient to prevent the reduction in serum vitamin D in autumn at 60° north latitude: a randomised trial.

Low serum concentrations of several vitamins have been linked to increased risk of diseases including insulin resistance and type 2 diabetes (T2D). Fish is a good source of several vitamins, and the prevalence of T2D is low in populations with high fish intake. The aim of the present study was to investigate the effects of high fish intake on vitamins in serum from adults in autumn in South-Western Norway at 60° north latitude. In this randomised clinical trial, sixty-three healthy participants with overweight/obesity consumed 750 g/week of either cod (n 22) or salmon (n 22) as five weekly dinners or were instructed to continue their normal eating habits but avoid fish intake (Control group, n 19) for 8 weeks. The estimated vitamin D intake was significantly increased in the Salmon group when compared with the Cod group (P = 6·3 × 10-4) and with the Control group (P = 3·5 × 10-6), with no differences between groups for estimated intake of vitamins A, B1, B2, B3, B6, B9, C and E. Serum 25-hydroxyvitamin D3 concentration was decreased in all groups after 8 weeks; however, the reduction in the Salmon group was significantly smaller compared with the Cod group (P = 0·013) and the Control group (P = 0·0060). Cod and salmon intake did not affect serum concentrations of the other measured vitamins. The findings suggest that 750 g/week of salmon was not sufficient to prevent a decrease in serum 25-hydroxyvitamin D3 in autumn in South-Western Norway in adults with overweight/obesity.

One-carbon metabolites, B vitamins and associations with systemic inflammation and angiogenesis biomarkers among colorectal cancer patients: results from the ColoCare Study.

B vitamins involved in one-carbon metabolism have been implicated in the development of inflammation- and angiogenesis-related chronic diseases, such as colorectal cancer (CRC). Yet, the role of one-carbon metabolism in inflammation and angiogenesis among CRC patients remains unclear. The objective of this study was to investigate associations of components of one-carbon metabolism with inflammation and angiogenesis biomarkers among newly diagnosed CRC patients (n 238) in the prospective ColoCare Study, Heidelberg. We cross-sectionally analysed associations between twelve B vitamins and one-carbon metabolites and ten inflammation and angiogenesis biomarkers from pre-surgery serum samples using multivariable linear regression models. We further explored associations among novel biomarkers in these pathways with Spearman partial correlation analyses. We hypothesised that pyridoxal-5'-phosphate (PLP) is inversely associated with inflammatory biomarkers. We observed that PLP was inversely associated with C-reactive protein (CRP) (r -0·33, Plinear < 0·0001), serum amyloid A (SAA) (r -0·23, Plinear = 0·003), IL-6 (r -0·39, Plinear < 0·0001), IL-8 (r -0·20, Plinear = 0·02) and TNFα (r -0·12, Plinear = 0·045). Similar findings were observed for 5-methyl-tetrahydrofolate and CRP (r -0·14), SAA (r -0·14) and TNFα (r -0·15) among CRC patients. Folate catabolite acetyl-para-aminobenzoylglutamic acid (pABG) was positively correlated with IL-6 (r 0·27, Plinear < 0·0001), and pABG was positively correlated with IL-8 (r 0·21, Plinear < 0·0001), indicating higher folate utilisation during inflammation. Our data support the hypothesis of inverse associations between PLP and inflammatory biomarkers among CRC patients. A better understanding of the role and inter-relation of PLP and other one-carbon metabolites with inflammatory processes among colorectal carcinogenesis and prognosis could identify targets for future dietary guidance for CRC patients.