The inverse association between the apolipoprotein E ε4 allele and C-reactive protein levels is stronger in persons with obesity and diabetes.

BACKGROUND: C-reactive protein (CRP) is lower in patients who carry the apolipoprotein E epsilon 4 allele variant (APOEε4) of the APOE gene. This could however be explained by other factors observed in APOEε4 carriers, such as lower body mass index (BMI), possibly less diabetes and more use of statins, all associated with CRP concentrations. OBJECTIVES: To assess the association between CRP and APOEε4 stratified by BMI, statin use and diabetes. METHODS: We included 2700 community-dwelling older adults from the Hordaland health study with genotyping of the APOE gene by a one-step polymerase chain reaction and CRP measured using immuno-MALDI-TOF MS. Differences in CRP concentrations by APOE (ε4 vs no ε4) were assessed using the Mann-Whitney U tests, also stratified by statin use, diabetes and BMI categories. Finally, we performed linear regression with log (CRP) as the outcome and APOEε4 together with statin use, diabetes, BMI and their respective interactions. RESULTS: CRP was higher in APOEε4 carriers irrespective of BMI, diabetes and statin use. In APOEε4 non-carriers, CRP was elevated with diabetes and obesity as expected. However, this was attenuated or even reversed in APOEε4 carriers. Such differences were not observed for statin use. CONCLUSIONS: Statin use, obesity or diabetes did not confound the known association between the APOEε4 allele and lower CRP. Our data suggest that CRP is less responsive to inflammatory cues involved in diabetes and obesity in APOEε4 carriers. Epidemiological studies should take note of these relationships, as CRP, APOEε4, diabetes and obesity are both linked to neurodegenerative and cardiovascular disease.

Inflammation, the kynurenines, and mucosal injury during human experimental enterotoxigenic Escherichia coli infection.

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children and travelers, especially in low- and middle-income countries. ETEC is a non-invasive gut pathogen colonizing the small intestinal wall before secreting diarrhea-inducing enterotoxins. We sought to investigate the impact of ETEC infection on local and systemic host defenses by examining plasma markers of inflammation and mucosal injury as well as kynurenine pathway metabolites. Plasma samples from 21 volunteers experimentally infected with ETEC were collected before and 1, 2, 3, and 7 days after ingesting the ETEC dose, and grouped based on the level of intestinal ETEC proliferation: 14 volunteers experienced substantial proliferation (SP) and 7 had low proliferation (LP). Plasma markers of inflammation, kynurenine pathway metabolites, and related cofactors (vitamins B2 and B6) were quantified using targeted mass spectrometry, whereas ELISA was used to quantify the mucosal injury markers, regenerating islet-derived protein 3A (Reg3a), and intestinal fatty acid-binding protein 2 (iFABP). We observed increased concentrations of plasma C-reactive protein (CRP), serum amyloid A (SAA), neopterin, kynurenine/tryptophan ratio (KTR), and Reg3a in the SP group following dose ingestion. Vitamin B6 forms, pyridoxal 5'-phosphate and pyridoxal, decreased over time in the SP group. CRP, SAA, and pyridoxic acid ratio correlated with ETEC proliferation levels. The changes following experimental ETEC infection indicate that ETEC, despite causing a non-invasive infection, induces systemic inflammation and mucosal injury when proliferating substantially, even in cases without diarrhea. It is conceivable that ETEC infections, especially when repeated, contribute to negative health impacts on children in ETEC endemic areas.

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.

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.

Homocysteine, the methylenetetrahydrofolate reductase 677C>T polymorphism and hypertension: effect modifiers by lifestyle factors and population subgroups.

Evidence linking fasting plasma total homocysteine (tHcy) and methylenetetrahydrofolate reductase (MTHFR) 677C>T genotype with hypertension is inconsistent. Differences in B vitamin status, other lifestyle factors or their consideration in analyses might explain this. We investigated these associations in the absence of mandatory fortification with folic acid and B vitamin supplement use. A cross-sectional study was conducted in 788 adults, aged 18-75 years, randomly selected from three Catalonian town population registers. Fasting plasma folate, cobalamin, tHcy, erythrocyte folate, erythrocyte glutathione reductase activation coefficient (EGRAC, functional riboflavin status indicator; increasing EGRAC indicates worsening riboflavin status), MTHFR 677C>T and solute carrier family 1 (SLC19A1) 80 G>A genotypes were determined. Medical history and lifestyle habits were recorded. Principal tHcy determinants differed between women (age, plasma folate, plasma cobalamin, cigarettes/d) and men (MTHFR 677TT genotype, plasma folate, plasma cobalamin and CT genotype). The MTHFR 677C>T polymorphism-tHcy association (ß standardised regression coefficients) was stronger in male smokers (0·52, P < 0·001) compared with non-smokers (0·21, P = 0·001) and weaker in participants aged >50 years (0·19, P = 0·007) compared with ≤50 years (0·31, P < 0·001). Hypertension was more probable in the third tHcy tertile compared with other tertiles (OR 1·9; 95 % CI 1·2, 3·0), and in participants aged ≤50 years, for the MTHFR 677TT genotype compared with the CC genotype (OR 4·1; 95 % CI 1·0, 16·9). EGRAC was associated with increased probability of hypertension in participants aged >50 years (OR 6·2; 95 % CI 1·0, 38·7). In conclusion, moderately elevated tHcy and the MTHFR 677CT genotype were associated with hypertension. The MTHFR 677C>T genotype-hypertension association was confined to adults aged ≤50 years.

Comparative analysis of chromosome 2A molecular organization in diploid and hexaploid wheat.

Diploid A genome wheat species harbor immense genetic variability which has been targeted and proven useful in wheat improvement. Development and deployment of sequence-based markers has opened avenues for comparative analysis, gene transfer and marker assisted selection (MAS) using high throughput cost effective genotyping techniques. Chromosome 2A of wheat is known to harbor several economically important genes. The present study aimed at identification of genic sequences corresponding to full length cDNAs and mining of SSRs and ISBPs from 2A draft sequence assembly of hexaploid wheat cv. Chinese Spring for marker development. In total, 1029 primer pairs including 478 gene derived, 501 SSRs and 50 ISBPs were amplified in diploid A genome species Triticum monococcum and T. boeoticum identifying 221 polymorphic loci. Out of these, 119 markers were mapped onto a pre-existing chromosome 2A genetic map consisting of 42 mapped markers. The enriched genetic map constituted 161 mapped markers with final map length of 549.6 cM. Further, 2A genetic map of T. monococcum was anchored to the physical map of 2A of cv. Chinese Spring which revealed several rearrangements between the two species. The present study generated a highly saturated genetic map of 2A and physical anchoring of genetically mapped markers revealed a complex genetic architecture of chromosome 2A that needs to be investigated further.

The kynurenine pathway and cognitive performance in community-dwelling older adults. The Hordaland Health Study.

INTRODUCTION: Tryptophan, its downstream metabolites in the kynurenine pathway and neopterin have been associated with inflammation and dementia. We aimed to study the associations between plasma levels of these metabolites and cognitive function in community-dwelling, older adults. METHODS: This cross-sectional study included 2174 participants aged 70-72 years of the community-based Hordaland Health Study. Tryptophan, kynurenine, neopterin and eight downstream kynurenines were measured in plasma. Kendrick Object Learning Test (KOLT), Digit Symbol Test (DST) and the Controlled Oral Word Association Test (COWAT) were all outcomes in standardized Zellner's regression. The Wald test of a composite linear hypothesis of an association with each metabolite was adjusted by the Bonferroni method. Age, body mass index, C-reactive protein, depressive symptoms, diabetes, education, glomerular filtration rate, hypertension, previous myocardial infarction, prior stroke, pyridoxal 5'phosphate, sex and smoking were considered as potential confounders. RESULTS: Higher levels of the kynurenine-to-tryptophan ratio (KTR) and neopterin were significantly associated with poorer, overall cognitive performance (p < 0.002). Specifically, KTR was negatively associated with KOLT (ß -0.08, p = 0.001) and COWAT (ß -0.08, p = 0.001), but not with DST (ß -0.03, p = 0.160). This pattern was also seen for neopterin (KOLT: ß -0.07; p = 0.001; COWAT: ß -0.06, p = 0.010; DST: ß -0.01, p = 0.800). The associations were not confounded by the examined variables. No significant associations were found between the eight downstream kynurenines and cognition. CONCLUSION: Higher KTR and neopterin levels, biomarkers of cellular immune activation, were associated with reduced cognitive performance, implying an association between the innate immune system, memory, and language.

Ceramide stearic to palmitic acid ratio predicts incident diabetes.

AIMS/HYPOTHESIS: Ceramide lipids have a role in the development of insulin resistance, diabetes and risk of cardiovascular disease. Here we investigated four ceramides and their ratios to find the best predictors of incident diabetes. METHODS: A validated mass-spectrometric method was applied to measure Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/24:0) and Cer(d18:1/24:1) from serum or plasma samples. These ceramides were analysed in a population-based risk factor study (FINRISK 2002, n = 8045), in a cohort of participants undergoing elective coronary angiography for suspected stable angina pectoris (Western Norway Coronary Angiography Cohort [WECAC], n = 3344) and in an intervention trial investigating improved methods of lifestyle modification for individuals at high risk of the metabolic syndrome (Prevent Metabolic Syndrome [PrevMetSyn], n = 371). Diabetes risk score models were developed to estimate the 10 year risk of incident diabetes. RESULTS: Analysis in FINRISK 2002 showed that the Cer(d18:1/18:0)/Cer(d18:1/16:0) ceramide ratio was predictive of incident diabetes (HR per SD 2.23, 95% CI 2.05, 2.42), and remained significant after adjustment for several risk factors, including BMI, fasting glucose and HbA1c (HR 1.34, 95% CI 1.14, 1.57). The finding was validated in the WECAC study (unadjusted HR 1.81, 95% CI 1.53, 2.14; adjusted HR 1.39, 95% CI 1.16, 1.66). In the intervention trial, the ceramide ratio and diabetes risk scores significantly decreased in individuals who had 5% or more weight loss. CONCLUSIONS/INTERPRETATION: The Cer(d18:1/18:0)/Cer(d18:1/16:0) ratio is an independent predictive biomarker for incident diabetes, and may be modulated by lifestyle intervention.

Impaired functional vitamin B6 status is associated with increased risk of lung cancer.

Circulating vitamin B6 levels have been found to be inversely associated with lung cancer. Most studies have focused on the B6 form pyridoxal 5'-phosphate (PLP), a direct biomarker influenced by inflammation and other factors. Using a functional B6 marker allows further investigation of the potential role of vitamin B6 status in the pathogenesis of lung cancer. We prospectively evaluated the association of the functional marker of vitamin B6 status, the 3-hydroxykynurenine:xanthurenic acid (HK:XA) ratio, with risk of lung cancer in a nested case-control study consisting of 5,364 matched case-control pairs from the Lung Cancer Cohort Consortium (LC3). We used conditional logistic regression to evaluate the association between HK:XA and lung cancer, and random effect models to combine results from different cohorts and regions. High levels of HK:XA, indicating impaired functional B6 status, were associated with an increased risk of lung cancer, the odds ratio comparing the fourth and the first quartiles (OR4thvs.1st ) was 1.25 (95% confidence interval, 1.10-1.41). Stratified analyses indicated that this association was primarily driven by cases diagnosed with squamous cell carcinoma. Notably, the risk associated with HK:XA was approximately 50% higher in groups with a high relative frequency of squamous cell carcinoma, i.e., men, former and current smokers. This risk of squamous cell carcinoma was present in both men and women regardless of smoking status.

Multiplex Immuno-MALDI-TOF MS for Targeted Quantification of Protein Biomarkers and Their Proteoforms Related to Inflammation and Renal Dysfunction.

Circulating proteins are widely used as biomarkers in clinical applications for the diagnosis, prediction, and treatment of numerous diseases. Immunoassays are the most common technologies for quantification of protein biomarkers and exist in various formats. Traditional immunoassays offer sensitive and fast analyses but cannot differentiate between proteoforms. Protein microheterogeneity, mainly due to post-translational modification, has been recognized as a fingerprint for different pathologies, and knowledge about proteoforms is an important step toward personalized medicine. Mass spectrometry (MS) has emerged to be a powerful technique for the characterization and quantification of proteoforms. We have established a novel four-plex immunoassay based on Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF) MS for the targeted quantification of the inflammatory markers C-reactive protein (CRP), serum amyloid A (SAA), and calprotectin (S100A8/9) and the kidney function marker cystatin C (CysC). Antibodies were covalently bound to superparamagnetic beads, which delivered robust and fast sample processing. Polyhistidine-tagged recombinant target proteins were used as internal standards for quantification. Our method identified a number of proteoforms for SAA ( n = 11), S100A8/9 ( n = 4) and CysC ( n = 4). The assay was characterized by low limits of detection (0.01-0.06 µg/mL) and low coefficients of variation (3.8-9.4%). Method validation demonstrated good between-assay agreement with immuno-turbidimetry ( R2 = 0.963 for CRP), ELISA ( R2 = 0.958 for SAA; R2 = 0.913 for S100A8/9), and nephelometry ( R2 = 0.963 for CysC). The low sample consumption of 20 µL and the high sample throughput of 384 samples per day make this targeted immuno-MALDI approach suited for assessment of inflammatory and renal status in large cohort studies based on precious biobanks samples.

Dietary Choline Intake Is Directly Associated with Bone Mineral Density in the Hordaland Health Study.

Background: Choline is an important nutrient either obtained from a variety of foods or synthesized endogenously, and it is the precursor of betaine. We previously reported positive associations between plasma free choline and bone mineral density (BMD). Animal studies suggest an impact of dietary choline on bone metabolism, but the role of dietary intake of choline and betaine for human bone health is unknown.Objectives: The main aims were to examine the associations of dietary choline, choline species, and betaine with BMD and to study the relations between dietary and plasma free choline and betaine.Methods: Study subjects were participants in the Hordaland Health Study, including 2649 women and 1983 men (aged 46-49 or 71-74 y). BMD was measured by dual-energy X-ray absorptiometry, and dietary intake was obtained by using a validated 169-item food-frequency questionnaire. Risk associations were assessed by logistic regression and correlations by ρ (Spearman's bivariate rank order correlation).Results: Subjects in the lowest compared with the highest tertile of dietary total choline, free choline, glycerophosphocholine, phosphocholine, phosphatidylcholine, and sphingomyelin had a higher risk of low-femoral neck BMD, defined as the lowest BMD quintile. Particularly strong associations were found among middle-aged men for intake of free choline (OR: 1.83; 95% CI: 1.24, 2.69; P = 0.002) and glycerophosphocholine (OR: 2.13; 95% CI: 1.43, 3.16; P < 0.001) and among elderly women for total choline (OR: 1.96; 95% CI: 1.33, 2.88; P = 0.001) and phosphatidylcholine (OR: 1.94; 95% CI: 1.33, 2.84: P = 0.001) intake. No significant associations were observed between dietary betaine and BMD. Dietary total choline, free choline, glycerophosphocholine, phosphatidylcholine, and sphingomyelin correlated weakly with plasma free choline (ρ: 0.07, 0.05, 0.07, 0.07, and 0.05, respectively; P < 0.01). Dietary betaine correlated with plasma betaine (ρ: 0.23; P < 0.001).Conclusion: Dietary choline was positively associated with BMD in middle-aged and elderly participants.

Plasma Biomarkers of Inflammation, the Kynurenine Pathway, and Risks of All-Cause, Cancer, and Cardiovascular Disease Mortality: The Hordaland Health Study.

We aimed to evaluate 10 biomarkers related to inflammation and the kynurenine pathway, including neopterin, kynurenine:tryptophan ratio, C-reactive protein, tryptophan, and 6 kynurenines, as potential predictors of all-cause and cause-specific mortality in a general population sample. The study cohort was participants involved in a community-based Norwegian study, the Hordaland Health Study (HUSK). We used Cox proportional hazards models to assess associations of the biomarkers with all-cause mortality and competing-risk models for cause-specific mortality. Of the 7,015 participants, 1,496 deaths were recorded after a median follow-up time of 14 years (1998-2012). Plasma levels of inflammatory markers (neopterin, kynurenine:tryptophan ratio, and C-reactive protein), anthranilic acid, and 3-hydroxykynurenine were positively associated with all-cause mortality, and tryptophan and xanthurenic acid were inversely associated. Multivariate-adjusted hazard ratios for the highest (versus lowest) quartiles of the biomarkers were 1.19-1.60 for positive associations and 0.73-0.87 for negative associations. All of the inflammatory markers and most kynurenines, except kynurenic acid and 3-hydroxyanthranilic acid, were associated with cardiovascular disease (CVD) mortality. In this general population, plasma biomarkers of inflammation and kynurenines were associated with risk of all-cause, cancer, and CVD mortality. Associations were stronger for CVD mortality than for mortality due to cancer or other causes.

Combined Measurement of 6 Fat-Soluble Vitamins and 26 Water-Soluble Functional Vitamin Markers and Amino Acids in 50 µL of Serum or Plasma by High-Throughput Mass Spectrometry.

Targeted metabolic profiling characterized by complementary platforms, multiplexing and low volume consumption are increasingly used for studies using biobank material. Using liquid-liquid extraction, we developed a sample workup suitable for quantification of 6 fat- and 26 water-soluble biomarkers. 50 µL of serum/plasma was mixed with dithioerythritol, ethanol, and isooctane/chloroform. The organic layer was used for analysis of the fat-soluble vitamins all-trans retinol (A), 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, α-tocopherol (E), γ-tocopherol (E), and phylloquinone (K1) by LC-MS/MS. The remaining aqueous fraction was mixed with ethanol, water, pyridine, and methylchloroformate (in toluene) to derivatize the water-soluble biomarkers. The resulting toluene layer was used for GC-MS/MS analysis of alanine, α-ketoglutarate, asparagine, aspartic acid, cystathionine, total cysteine, glutamic acid, glutamine, glycine, histidine, total homocysteine, isoleucine, kynurenine, leucine, lysine, methionine, methylmalonic acid, ornithine, phenylalanine, proline, sarcosine, serine, threonine, tryptophan, tyrosine, and valine. Isotope-labeled internal standards were used for all analytes. Chromatographic run times for the LC-MS/MS and GC-MS/MS were 4.5 and 11 min, respectively. The limits of detection (LOD) for the low-concentration analytes (25-hydroxyvitamin D2, 25-hydroxyvitamin D3, and phylloquinone) were 25, 17, and 0.33 nM, respectively, while all other analytes demonstrated sensitivity significantly lower than endogenous concentrations. Recoveries ranged from 85.5-109.9% and within- and between-day coefficients of variance (CVs) were 0.7-9.4% and 1.1-17.5%, respectively. This low-volume, high-throughput multianalyte assay is currently in use in our laboratory for quantification of 32 serum/plasma biomarkers in epidemiological studies.

Common Polymorphisms That Affect Folate Transport or Metabolism Modify the Effect of the MTHFR 677C > T Polymorphism on Folate Status.

BACKGROUND: Although combinations of biologically relevant polymorphic variants affect folate status, most studies have focused on the effects of individual polymorphisms; however, these effects may be altered by interactions between polymorphisms. OBJECTIVE: We investigated the individual and combined effects of polymorphisms that affect folate transport or metabolism on folate status. METHODS: The associations between the methylenetetrahydrofolate reductase (MTHFR) 677C > T, methionine transferase reductase (MTRR) 66A > G, MTRR 524C > T, 5,10-methylenetetrahydrofolate dehydrogenase-5,10-methylenetetrahydrofolate cyclohydrolase-10-formyltetrahydrofolate synthetase (MTHFD1) 1958G > A, MTHFD1 -105C > T, dihydrofolate reductase (DHFR) 19-bp insertion/deletion, and solute carrier family 19A, member 1 (SLC19A1) 80G > A polymorphisms and fasting plasma folate (PF), red cell folate (RCF), and plasma total homocysteine (tHcy) were tested by ANCOVA and Cox regression analysis in 781 Spanish adults. RESULTS: Folate deficiency (PF <7 nmol/L) was observed in 18.8% of the participants. Geometric mean PF (nmol/L) was lower in MTHFR 677TT (10.0; 95% CI: 9.2, 11.9) compared with 677CC (12.4; 95% CI: 11.6, 13.2; P < 0.001). RCF (nmol/L) was lower in MTHFR 677TT (652; 95% CI: 611, 695) compared with 677CC (889; 95% CI: 851, 929; P < 0.001) and in SLC19A1 80AA (776; 95% CI: 733, 822) compared with 80GG (861; 95% CI: 815, 910; P < 0.01). RCF and tHcy (µmol/L) did not differ in MTHFR + MTRR 677TT/524TT compared with 677CC/524CC: 780 (95% CI: 647, 941) compared with 853 (95% CI: 795, 915; P = 0.99) and 10.2 (95% CI: 8.4, 12.3) compared with 8.9 (95% CI: 8.5, 9.4; P = 0.99), respectively. The RR of lowest-tertile RCF (≤680 nmol/L) was 2.1 (95% CI: 1.0, 4.5) for MTHFR + MTRR 677TT/66GG compared with 677CC/66AA, 2.2 (95% CI: 1.2, 4.1) for MTHFR + MTHFD1 677TT/1958AA compared with 677CC/1958GG, 2.9 (95% CI: 1.4, 6.0) for MTHFR + MTHFD1 677TT/-105TT compared with 677CC/-105CC, and 3.5 (95% CI: 1.5, 8.1) for MTHFR + SLC19A1 677TT/80AA compared with 677CC/80GG. Confining the analysis to the MTHFR 677TT genotype, the risk of lowest-tertile RCF was reduced for MTHFR + MTRR 677TT/66GG compared with 677TT/66AA (RR: 0.5; 95% CI: 0.3, 0.9). CONCLUSIONS: Folate status was lower in the MTHFR 677TT and SLC19A1 80AA genotypes compared with corresponding reference genotypes. Low folate status risk associated with the MTHFR 677TT genotype varied depending on its combination with other polymorphisms.

Serum Immune System Biomarkers Neopterin and Interleukin-10 Are Strongly Related to Tryptophan Metabolism in Healthy Young Adults.

BACKGROUND: Changes in tryptophan metabolism through the vitamin B-6-dependent kynurenine pathway have been linked to activation of the immune system. OBJECTIVE: We hypothesized that blood concentrations of tryptophan and its catabolites were associated with biomarkers relevant to inflammatory processes in healthy noninflamed subjects. METHODS: Healthy young adults (n = 737) aged 18-28 y without any known diseases or clinical evidence of inflammation provided blood samples for analysis of serum tryptophan/kynurenine metabolites, neopterin, C-reactive protein (CRP), and plasma pyridoxal 5'-phosphate (PLP) with LC-tandem mass spectrometry methodologies. A panel of cytokines was measured in serum by using high-sensitivity ELISA assays. Anthropometric and lifestyle data were collected by questionnaire. Multiple linear regression analysis to determine the effect of measured serum cytokine concentrations as predictors of tryptophan metabolites was performed on inverse normal-rank transformations of the data, adjusted for sex, body mass index, smoking, alcohol intake, and contraceptive use in women. RESULTS: Median serum CRP and neopterin concentrations were well below established clinical cutoffs for inflammation. We observed significant positive associations between serum interleukin-10 (IL-10) and serum kynurenine (P = 0.0002), the kynurenine-to-tryptophan ratio (KTR) (P = 0.003), 3-hydroxykynurenine (P = 0.01), and 3-hydroxyanthranilic acid (P = 0.04). Serum neopterin was positively associated with kynurenine, the KTR (both P < 0.0001), and anthranilic acid (P = 0.004), and was negatively associated with serum tryptophan (P = 0.01) and PLP (P < 0.0001). Serum tumor necrosis factor α was also negatively associated with tryptophan (P < 0.001). CONCLUSIONS: In healthy young adults with no apparent inflammatory conditions, serum tryptophan metabolites are significantly associated with key immune system biomarkers. The observed association between IL-10 and kynurenine is unexpected and suggests that kynurenine-linked mechanisms promoting negative regulation of inflammatory responses are associated with normal immune homeostasis.

Associations of plasma kynurenines with risk of acute myocardial infarction in patients with stable angina pectoris.

OBJECTIVE: Enhanced tryptophan degradation, induced by the proinflammatory cytokine interferon-γ, has been related to cardiovascular disease progression and insulin resistance. We assessed downstream tryptophan metabolites of the kynurenine pathway as predictors of acute myocardial infarction in patients with suspected stable angina pectoris. Furthermore, we evaluated potential effect modifications according to diagnoses of pre-diabetes mellitus or diabetes mellitus. APPROACH AND RESULTS: Blood samples were obtained from 4122 patients (median age, 62 years; 72% men) who underwent elective coronary angiography. During median follow-up of 56 months, 8.3% had acute myocardial infarction. Comparing the highest quartile to the lowest, for the total cohort, multivariable adjusted hazard ratios (95% confidence intervals) were 1.68 (1.21-2.34), 1.81 (1.33-2.48), 1.68 (1.21-2.32), and 1.48 (1.10-1.99) for kynurenic acid, hydroxykynurenine, anthranilic acid, and hydroxyanthranilic acid, respectively. The kynurenines correlated with phenotypes of the metabolic syndrome, and risk associations were generally stronger in subgroups classified with pre-diabetes mellitus or diabetes mellitus at inclusion (Pint≤0.05). Evaluated in the total population, hydroxykynurenine and anthranilic acid provided statistically significant net reclassification improvements (0.21 [0.08-0.35] and 0.21 [0.07-0.35], respectively). CONCLUSIONS: In patients with suspected stable angina pectoris, elevated levels of plasma kynurenines predicted increased risk of acute myocardial infarction, and risk estimates were generally stronger in subgroups with evidence of impaired glucose homeostasis. Future studies should aim to clarify roles of the kynurenine pathway in atherosclerosis and glucose metabolism.

Markers of vitamin B6 status and metabolism as predictors of incident cancer: the Hordaland Health Study.

Dietary intake and/or circulating concentrations of vitamin B6 have been associated with risk of cancer, but results are inconsistent and mechanisms uncertain. Pyridoxal 5'-phosphate (PLP) is the most commonly used marker of B6 status. We recently proposed the ratio 3-hydroxykynurenine/xanthurenic acid (HK/XA) as an indicator of functional vitamin B6 status, and the 4-pyridoxic acid (PA) /(pyridoxal (PL) +PLP) ratio (PAr) as a marker of vitamin B6 catabolism during inflammation. We compared plasma PLP, HK/XA and PAr as predictors of cancer incidence in a prospective community-based cohort in Norway. This study included 6,539 adults without known cancer at baseline (1998-99) from the Hordaland Health Study (HUSK). HR and 95% CI were calculated for the risk of overall and site-specific cancers using multivariate Cox proportional hazards regression with adjustment for potential confounders. After a median follow-up time of 11.9 years, 963 cancer cases (501 men and 462 women) were identified. Multivariate-adjusted Cox-regression showed no significant relation of plasma PLP or HK/XA with risk of incident cancer. In contrast, PAr was significantly associated with risk of cancer with HR (95% CI) = 1.31 (1.12-1.52) per two standard deviation (SD) increment (p < 0.01). Further analysis showed that PAr was a particular strong predictor of lung cancer with HR (95% CI) = 2.46 (1.49-4.05) per two SD increment (p < 0.01). The present results indicate that associations of vitamin B6 with cancer may be related to increased catabolism of vitamin B6, in particular for lung cancer where inflammation may be largely involved in carcinogenesis.

Sarcosine and other metabolites along the choline oxidation pathway in relation to prostate cancer--a large nested case-control study within the JANUS cohort in Norway.

Methyl group donors and intermediates of one-carbon metabolism affect DNA synthesis and DNA methylation, and may thereby affect prostate carcinogenesis. Choline, the precursor of betaine, and the one-carbon metabolite sarcosine have been associated with increased prostate cancer risk. Within JANUS, a prospective cohort in Norway (n = 317,000) with baseline serum samples, we conducted a nested case-control study among 3,000 prostate cancer cases and 3,000 controls. Using conditional logistic regression, odds ratios (ORs) and 95% confidence intervals (CIs) for prostate cancer risk were estimated according to quintiles of circulating betaine, dimethylglycine (DMG), sarcosine, glycine and serine. High sarcosine and glycine concentrations were associated with reduced prostate cancer risk of borderline significance (sarcosine: highest vs. lowest quintile OR = 0.86, CI = 0.72-1.01, p(trend) = 0.03; glycine: OR = 0.83, CI = 0.70-1.00, p(trend) = 0.07). Serum betaine, DMG and serine were not associated with prostate cancer risk. However, individuals with a high glycine/serine ratio were at decreased prostate cancer risk (OR = 0.74, CI = 0.69-0.85, p(trend) < 0.001). This population-based study suggested that men with high serum sarcosine or glycine concentrations have modestly reduced prostate cancer risk. Ratios of metabolites reflecting one-carbon balance may be associated with prostate cancer risk, as demonstrated for the glycine/serine ratio, and should be explored in future studies.

Interferon-γ-induced inflammatory markers and the risk of cancer: the Hordaland Health Study.

BACKGROUND: It has been reported that interferon-γ (IFN-γ)-induced inflammatory markers, such as circulating neopterin and kynurenine-to-tryptophan ratio (KTR), are increased in patients with cancer and are also a predictor of poor prognosis. However, whether baseline levels of these makers are associated with subsequent cancer risk in the general population remains unknown. METHODS: We conducted a prospective analysis of the Hordaland Health Study in 6594 adults without known cancer at baseline who were enrolled between April 1998 and June 1999. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using multivariate Cox proportional hazards regression models adjusted for sex, age, body mass index, smoking status, and renal function. RESULTS: A total of 971 incident cancer cases (507 men and 464 women) were identified over a median follow-up time of 12 years. Baseline plasma neopterin, KTR and C-reactive protein (CRP) were significantly associated with an increased risk of overall cancer in models adjusted for covariates (P for trend across quartiles = .006 for neopterin, .022 for KTR, and .005 for CRP). The multivariate-adjusted HR (95% CI) per SD increment in similar models were 1.09 (1.03-1.16) for neopterin, 1.07 (1.01-1.14) for KTR, and 1.04 (0.98-1.10) for CRP. The associations between the inflammatory markers and risk of major specific cancer types were also provided. CONCLUSIONS: Our findings indicate that plasma neopterin, KTR, and CRP are associated with a significantly increased risk of overall cancer. Our study revealed novel evidence regarding the role of IFN-γ-induced inflammation in human carcinogenesis.