Plasma Pyridoxal Phosphate Research Articles

Association between dietary macronutrient composition and plasma one-carbon metabolites and B-vitamin cofactors in patients with stable angina pectoris.

Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon metabolites can influence circulating concentrations of these markers. We cross-sectionally analysed 1928 patients with suspected stable angina pectoris (geometric mean age 61), representing elevated CVD risk, to assess associations between dietary macronutrient composition (FFQ) and plasma one-carbon metabolites and related B-vitamin status markers (GC-MS/MS, LC-MS/MS or microbiological assay). Diet-metabolite associations were modelled on the continuous scale, adjusted for age, sex, BMI, smoking, alcohol and total energy intake. Average (geometric mean (95 % prediction interval)) intake was forty-nine (38, 63) energy percent (E%) from carbohydrate, thirty-one (22, 45) E% from fat and seventeen (12, 22) E% from protein. The strongest associations were seen for higher protein intake, i.e. with higher plasma pyridoxal 5'-phosphate (PLP) (% change (95 % CI) 3·1 (2·1, 4·1)), cobalamin (2·9 (2·1, 3·7)), riboflavin (2·4 (1·1, 3·7)) and folate (2·1 (1·2, 3·1)) and lower total homocysteine (tHcy) (-1·4 (-1·9, -0·9)) and methylmalonic acid (MMA) (-1·4 (-2·0, -0·8)). Substitution analyses replacing MUFA or PUFA with SFA demonstrated higher plasma concentrations of riboflavin (5·0 (0·9, 9·3) and 3·3 (1·1, 5·6)), tHcy (2·3 (0·7, 3·8) and 1·3 (0·5, 2·2)) and MMA (2·0 (0·2, 3·9) and 1·7 (0·7, 2·7)) and lower PLP (-2·5 (-5·3, 0·3) and -2·7 (-4·2, -1·2)). In conclusion, a higher protein intake and replacing saturated with MUFA and PUFA were associated with a more favourable metabolic phenotype regarding metabolites associated with CVD risk.

Vitamin B6: a scoping review for Nordic Nutrition Recommendations 2023.

Pyridoxal 5´-phosphate (PLP) is the main form of vitamin B6 in animal tissue and functions as a coenzyme for more than 160 different enzymatic reactions in the metabolism of amino acids, carbohydrates, lipids, and neurotransmitters. Estimated dietary intake of vitamin B6 and plasma PLP values differ a lot between studies, something which may be due to variable use of supplements, variations in dietary assessment and analytical methods. These factors make it difficult to achieve precise data for setting a correct recommended intake of vitamin B6. In addition, a plasma PLP concentration of 30 nmol/L is considered to be sufficient and the current recommendations for vitamin B6 intake is based on this concept. However, the metabolic marker for vitamin B6 status, HK ratio (HKr), starts to increase already when plasma PLP falls below 100 nmol/L and increases more steeply below 50 nmol/L, indicating biochemical deficiency. Consequently, a plasma PLP concentration of 30 nmol/L, may be too low as a marker for an adequate vitamin B6 status.

Effects of maternal vitamin deficiency on the microstructure of the maternal hippocampus and behavior in offspring

ObjectivesNutrition plays a critical role in the brain's function and development. Vitamin B6 in the form of pyridoxal phosphate (PLP) is required for the biosynthesis of several neurotransmitters. As vitamin B6 is not endogenously synthesized, the availability of dietary sources becomes imperative. Due to its contribution to neurological functions, severe vitamin B6 deficiency leads to an increased risk of psychiatric disorders, dementia, and neurodevelopmental disorders. This study aimed to establish a vitamin B6-deficient model in experimental animals and assess the neurodevelopmental effects in their offspring. MethodsTwo- to three-month-old female C57BL/6J mice were used in the study. They were randomly divided into control and vitamin B6-deficient groups. The control group was fed a regular diet containing 6 mg vitamin B6/kg and the vitamin B6-deficient group was fed a customized diet containing 0 mg vitamin B6/kg, for 5 weeks (n = 6). After 5 weeks, plasma PLP was assessed. The animals were bred to generate offspring. The dams were killed following weaning, and the hippocampal neurons were quantified using cresyl violet staining. The offspring were assigned the respective diet post-weaning up to 2 months of age. Learning and memory were assessed using the Morris water maze test. ResultsThe plasma PLP levels confirmed the deficiency in the deficient group compared to the control group. The viable pyramidal neurons in the cornu ammonis 3 (CA3) region of the hippocampus showed a significant difference between the control and deficient groups. Offspring born to deficient dams showed a substantial increase in latency to reach the target quadrant during the probe trial compared to the controls. ConclusionVitamin B6 deficiency reduces memory in dams and their offspring, suggesting the importance of vitamin B6 for both brain function and development.

Vitamin B-6 Status Indices Are Lower in Pregnant than in Nonpregnant Women but Urinary Excretion of 4-Pyridoxic Acid Does Not Differ1–4

The cause of reduced plasma pyridoxal-5'-phosphate (PLP) concentration and the validity of plasma PLP concentration as a vitamin B-6 status indicator during pregnancy are not well understood. In this study, pregnant and nonpregnant women consumed a controlled diet for 5 d to exclude dietary intake as a factor in altered vitamin B-6 metabolic utilization. Plasma PLP and pyridoxal (PL) concentrations were significantly lower and higher, respectively, and plasma PL+PLP concentration was significantly lower during pregnancy. When plasma PLP and PL concentrations were normalized based on plasma albumin concentration, the differences were less marked but were still significant. The erythrocyte aspartate aminotransferase activity coefficient was significantly greater in pregnant women which is a further indication of reduced vitamin B-6 concentrations in the blood. No difference was observed in the urinary excretion of 4-pyridoxic acid between the pregnant and nonpregnant women. Results of this study demonstrate that vitamin B-6 status indices are lower during pregnancy without differences in the urinary excretion of 4-pyridoxic acid.

Vitamin B-6 Status of Women with a Constant Intake of Vitamin B-6 Changes with Three Levels of Dietary Protein

To determine the effect of varying levels of dietary protein with a constant intake of vitamin B-6 (B-6) on B-6 status, nine women were fed diets providing daily intakes of 1.25 mg B-6 and 0.5, 1.0 and 2.0 g protein/kg body weight. After an 8-d adjustment period, the women consumed each level of dietary protein for 14 d in a Latin-square design. Several direct and indirect B-6 status indicators were measured in blood and urine. Significant differences among protein levels were found for urinary 4-pyridoxic acid (4-PA) excretion (P < 0.01), plasma pyridoxal 5′-phosphate (PLP) concentration (P < 0.05), and urinary excretion of volatile amines (VA, kynurenine plus acetylkynurenine) after a 2-g L-tryptophan load (P < 0.05). Nitrogen intake was significantly negatively correlated with urinary 4-PA excretion (r = -0.619, P < 0.001) and plasma PLP concentration (r = -0.549, P < 0.01), and positively correlated with erythrocyte alanine aminotransferase percentage stimulation (r = 0.418, P < 0.05) and urinary post-tryptophan load excretion of xanthurenic acid (r = 0.535, P < 0.05), kynurenic acid (r = 0.563, P < 0.05) and VA (r = 0.626, P < 0.01). Compared with men consuming diets with similar B-6 to protein ratios in a previous study, the women excreted a greater percentage of the B-6 intake as 4-PA, had lower plasma PLP concentrations and excreted greater amounts of postload urinary tryptophan metabolites at all three protein levels. If the Recommended Dietary Allowance (RDA) of vitamin B-6 is to be based on the dietary B-6 to protein ratio, gender differences in response to varying protein intakes should be considered. For the levels of protein intake used in this study and a B-6 intake of 1.25 mg/d, a B-6 to protein ratio of greater than 0.020 mg/g is required for adequate vitamin B-6 status in women.

Vitamin B-6 and riboflavin, their metabolic interaction, and relationship with MTHFR genotype in adults aged 18–102 years

The generation of the active form of vitamin B-6, pyridoxal 5'-phosphate (PLP), in tissues is dependent upon riboflavin as flavin mononucleotide, but whether this interaction is important for maintaining vitamin B-6 status is unclear. To investigate vitamin B-6 and riboflavin status, their metabolic interaction, and relationship with methylenetetrahydrofolate reductase (MTHFR) genotype in adulthood. Data from 5612 adults aged 18-102 y were drawn from the Irish National Adult Nutrition Survey (NANS; population-based sample) and the Trinity-Ulster Department of Agriculture (TUDA) and Genovit cohorts (volunteer samples). Plasma PLP and erythrocyte glutathione reductase activation coefficient (EGRac), as a functional indicator of riboflavin, were determined. Older (≥65 y) compared with younger (<65 y) adults had significantly lower PLP concentrations (P<0.001). A stepwise decrease in plasma PLP was observed across riboflavin categories, from optimal (EGRac ≤1.26), to suboptimal (EGRac: 1.27-1.39), to deficient (EGRac ≥1.40) status, an effect most pronounced in older adults (mean±SEM: 76.4±0.9 vs 65.0±1.1 vs 55.4±1.2nmol/L; P<0.001). In individuals with the variant MTHFR 677TT genotype combined with riboflavin deficiency, compared with non-TT (CC/CT) genotype participants with sufficient riboflavin, we observed PLP concentrations of 52.1±2.9 compared with 76.8±0.7nmol/L (P<0.001). In participants with available dietary data (i.e., NANS cohort, n = 936), PLP was associated with vitamin B-6 intake (nonstandardized regression coefficient β: 2.49; 95% CI 1.75, 3.24; P<0.001), supplement use (β: 81.72; 95% CI: 66.01, 97.43; P<0.001), fortified food (β: 12.49; 95% CI: 2.08, 22.91; P=0.019), and EGRac (β: -65.81; 95% CI: -99.08, -32.54; P<0.001), along with BMI (β: -1.81; 95% CI: -3.31, -0.30; P=0.019). These results are consistent with the known metabolic dependency of PLP on flavin mononucleotide (FMN) and suggest that riboflavin may be the limiting nutrient for maintaining vitamin B-6 status, particularly in individuals with the MTHFR 677TT genotype. Randomized trials are necessary to investigate the PLP response to riboflavin intervention within the dietary range. The TUDA study and the NANS are registered at www.ClinicalTrials.gov as NCT02664584 (27 January 2016) and NCT03374748 (15 December 2017), respectively.Clinical Trial Registry details: Trinity-Ulster-Department of Agriculture (TUDA) study, ClinicalTrials.gov no. NCT02664584 (January 27th 2016); National Adult Nutrition Survey (NANS), ClinicalTrials.gov no. NCT03374748 (December 15th 2017).

Anticalcification effects of DS-1211 in pseudoxanthoma elasticum mouse models and the role of tissue-nonspecific alkaline phosphatase in ABCC6-deficient ectopic calcification

Pseudoxanthoma elasticum (PXE) is a multisystem, genetic, ectopic mineralization disorder with no effective treatment. Inhibition of tissue-nonspecific alkaline phosphatase (TNAP) may prevent ectopic soft tissue calcification by increasing endogenous pyrophosphate (PPi). This study evaluated the anticalcification effects of DS-1211, an orally administered, potent, and highly selective small molecule TNAP inhibitor, in mouse models of PXE. Calcium content in vibrissae was measured in KK/HlJ and ABCC6-/- mice after DS-1211 administration for 13–14 weeks. Pharmacokinetic and pharmacodynamic effects of DS-1211 were evaluated, including plasma alkaline phosphatase (ALP) activity and biomarker changes in PPi and pyridoxal-phosphate (PLP). Anticalcification effects of DS-1211 through TNAP inhibition were further evaluated in ABCC6-/- mice with genetically reduced TNAP activity, ABCC6-/-/TNAP+/+ and ABCC6-/-/TNAP+/-. In KK/HlJ and ABCC6-/- mouse models, DS-1211 inhibited plasma ALP activity in a dose-dependent manner and prevented progression of ectopic calcification compared with vehicle-treated mice. Plasma PPi and PLP increased dose-dependently with DS-1211 in ABCC6-/- mice. Mice with ABCC6-/-/TNAP+/- phenotype had significantly less calcification and higher plasma PPi and PLP than ABCC6-/-/TNAP+/+ mice. TNAP plays an active role in pathomechanistic pathways of dysregulated calcification, demonstrated by reduced ectopic calcification in mice with lower TNAP activity. DS-1211 may be a potential therapeutic drug for PXE.

Preventing Vitamin B6-Related Neurotoxicity.

Vitamin B6 is essential for life and plays a critical role in many biochemical and physiological processes in the human body. The term B6 collectively refers to 6 water-soluble vitamers, and only the pyridoxal 5'-phosphate (PLP) serves as the biologically active form. A plasma PLP concentration above 30 nmol/L (7.4 μg/L) is indicative of an adequate vitamin B6 status for all age and sex groups. The currently recommended daily allowance of B6 (1.5-2 mg/d) from dietary sources frequently results in inadequate B6 status (<20 nmol/L or 5 μg/L) in many elderly patients and patients with comorbid conditions. PLP-based supplements are preferred and should be administered weekly in low doses (50-100 mg) to maintain a stable serum PLP level between 30 and 60 nmol/L or 7.4 and 15 μg/L. It is challenging for physicians to prescribe a safe dose of B6 supplements because of the narrow therapeutic index. The association between elevated levels of pyridoxine and neuropathy is not well established. PLP-based supplements are shown to be least neurotoxic, but further clinical trials are needed to establish the long-term safety in high doses. PubMed search of randomized control trials and meta-analyses. Plasma B6 levels should be ordered as a part of workup of any unexplained anemia before labeling as "anemia of chronic disease." B6 supplementation is also crucial in the management of chronic Mg deficiency resistant to therapy. When B6 is administered daily in supraphysiologic doses, there is a potential for the development of neurotoxicity (typically at levels >100 nmol/L or 25 μg/L). PLP-based supplements are preferred over pyridoxine supplements because of minimal neurotoxicity observed in neuronal cell viability tests. Since B6 metabolites have a long half-life, weekly administration is preferred over daily use to prevent toxicity.

Urine phosphoethanolamine is a specific biomarker for hypophosphatasia in adults.

We investigated the utility of urine phosphoethanolamine (PEA) as a marker to aid in diagnosing and/or confirming hypophosphatasia (HPP) in adults and for monitoring patients on enzyme replacement therapy (ERT). Data was collected from seventy-eight adults who were referred to the Vanderbilt Program for Metabolic Bone Disease for evaluation of a possible or confirmatory HPP diagnosis between July 2014 through December 2019. Fifty-nine patients were diagnosed with HPP and nineteen were excluded from a diagnosis of HPP. The urine PEA results of those patients with a confirmed diagnosis of HPP and those patients with a diagnosis of HPP excluded were captured and compared to other laboratory and clinical parameters consistent with HPP, including alkaline phosphatase (ALP) activity, plasma pyridoxal 5'-phosphate (PLP), the presence of musculoskeletal abnormalities, and genetic testing for pathogenic mutations in ALPL. Initial urine PEA values in patients in our HPP cohort and not on ERT were significantly higher (median=150.0nmol/mg creatinine, IQR=82.0-202.0) compared patients in our HPP negative group (median 18.0nmol/mg creatinine, IQR=14.0-30.0, p<0.0001) and higher than patients on ERT (median 65.0nmol/mg creatinine, IQR=45.3-79.8). Patients who began ERT had a decline in urine PEA levels after treatment with a mean decrease of 68.1%. Plasma ALP levels were significantly lower in the group of patients with HPP and not on ERT group (median=24.0U/L, IQR=15.0-29.50) compared to the patients without HPP (median=45.50U/L, IQR=34.0-62.0;) and plasma PLP levels were significantly higher in the HPP non-ERT group (median=284.0nmol/L, IQR=141.0-469.4) compared to the patients without HPP (median=97.5nmol/L, IQR=43.7-206.0;). The area under the curve (AUC) of urine PEA, ALP, and PLP to distinguish between HPP and non-HPP patients is 0.968, 0.927 and 0.781, respectively, in our cohort. Urine PEA had 100% specificity (95% CI of 83.2% to 100.0%) for diagnosing HPP at a value >53.50nmol/mg creatinine with a sensitivity of 88.4%; 95%CI 75.5 to 94.9%. ALP had a 100% specificity (95% CI of 82.4% to 100.0%) for diagnosing HPP at a value <30.5U/L with a sensitivity of 77.2%; (95%CI 64.8 to 86.2%). PLP had a 100% specificity (95% CI of 81.6% to 100.0%) for diagnosing HPP at a value >436nmol/L with a sensitivity of 26.9%; (95%CI 16.8 to 40.3%). The most common pathogenic or likely pathogenic mutations in our cohort were c.1250A>G (p.Asn417Ser), c.1133A>T (p.Asp378Val), c.881A>C (p.Asp294Ala), c.1171C>T (p.Arg391Cys), and c.571G>A, (p.Glu191Lys). Urine PEA is a promising diagnostic and confirmatory marker for HPP in patients undergoing investigation for HPP. Urine PEA also has potential use as a marker to monitor ERT compliance. Future studies are necessary to evaluate the association between PEA levels and clinical outcomes.

Associations of Vitamin B6 Intake and Plasma Pyridoxal 5'-Phosphate with Plasma Polyunsaturated Fatty Acids in US Older Adults: Findings from NHANES 2003-2004.

Previous evidence suggests a potential dual impact of aging and vitamin B6 (B6) deficiency on polyunsaturated fatty acid (PUFA) metabolism; gender may influence PUFA biosynthesis. Perturbation of PUFA compositions during B6 deficiency could be linked to age-related health outcomes. However, little is known about the interrelationships between vitamin B6, PUFA, and gender in the older population. Therefore, we investigated whether gender-specific associations of B6 intake and plasma pyridoxal 5’-phosphate (PLP) concentration, respectively, with plasma PUFA concentrations and ratios (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), EPA + DHA, EPA/AA, and (EPA + DHA)/AA) existed in older adults. We further examined the relationships of adequate B6 status (PLP ≥ 20 nmol/L) with high (above median) plasma PUFA relative to deficient B6 status. This cross-sectional study analyzed 461 participants aged ≥60 years from NHANES 2003–2004. Nutrient intakes were assessed using two 24-h recalls and supplement questionnaires. PLP and PUFA concentrations were measured. Multivariate linear regression assessed the association of B6 intake and PLP with PUFA; multivariate logistic regression evaluated the relationship of adequate B6 status with high plasma PUFA, adjusting for demographic, socioeconomic, and dietary factors; physical activity; smoking; alcohol; medication; and BMI. There were interactions between gender and B6 intake on EPA (P-interaction = 0.008) and AA (P-interaction = 0.004) only, whereas no interaction existed between gender and PLP on PUFA. PLP was directly associated with EPA (β = 0.181, P = 0.002), DHA (β = 0.109, P = 0.005), EPA + DHA (β = 0.14, P = 0.002), EPA/AA (β = 0.186, P = 0.004), and (EPA + DHA)/AA (β = 0.13, P = 0.026). The odds of having high plasma EPA (adjusted (a) OR: 2.03, P = 0.049) and EPA/AA (aOR: 3.83, P < 0.0001) were greater in those with adequate B6 status compared to those with deficient B6 status. In conclusion, in US older adults, a higher PLP level was associated with a greater level of EPA, DHA, EPA + DHA, EPA/AA, and (EPA + DHA)/AA. Adequate B6 status was associated with high EPA and EPA/AA status. These findings suggest that sufficient vitamin B6 status may positively influence PUFA metabolism in older adults.

Associations between Genetic Variants and Blood Biomarkers of One-Carbon Metabolism in Postmenopausal Women from the Women's Health Initiative Observational Study

Genetic variation in one-carbon metabolism may affect nutrient concentrations and biological functions. However, data on genetic variants associated with blood biomarkers of one-carbon metabolism in US postmenopausal women are limited, and whether these associations were affected by the nationwide folic acid (FA) fortification program is unclear. We investigated associations between genetic variants and biomarkers of one-carbon metabolism using data from the Women's Health Initiative Observational Study. In 1573 non-Hispanic White (NHW) and 282 Black/African American, American Indian/Alaska Native, Asian/Pacific Islander, and Hispanic/Latino women aged 50-79 y, 288 nonsynonymous and tagging single-nucleotide variants (SNVs) were genotyped. RBC folate, plasma folate, pyridoxal-5'-phosphate (PLP), vitamin B-12, homocysteine, and cysteine concentrations were determined in 12-h fasting blood. Multivariable linear regression tested associations per variant allele and for an aggregated genetic risk score. Effect modifications before, during, and after nationwide FA fortification were examined. After correction for multiple comparisons, among NHW women, 5,10-methylenetetrahydrofolate reductase (MTHFR) rs1801133 (677C→T) variant T was associated with lower plasma folate (-13.0%; 95% CI: -17.3%, -8.6%) and higher plasma homocysteine (3.5%; 95% CI: 1.7%, 5.3%) concentrations. Other associations for nonsynonymous SNVs included DNMT3A rs11695471 (T→A) with plasma PLP; EHMT2 rs535586 (G→A), TCN2 rs1131603 (L349S A→G), and TCN2 rs35838082 (R188W G→A) with plasma vitamin B-12; CBS rs2851391 (G→A) with plasma homocysteine; and MTHFD1 rs2236224 (G→A) and rs2236225 (R653Q G→A) with plasma cysteine. The influence of FA fortification on the associations was limited. Highest compared with lowest quartiles of aggregated genetic risk scores from SNVs in MTHFR and MTRR were associated with 14.8% to 18.9% lower RBC folate concentrations. Gene-biomarker associations were similar in women of other races/ethnicities. Our findings on genetic variants associated with several one-carbon metabolism biomarkers may help elucidate mechanisms of maintaining B vitamin status in postmenopausal women.

Hypophosphatasia: Vitamin B6 status of affected children and adults.

Hypophosphatasia (HPP) is the heritable dento-osseous disease caused by loss-of-function mutation(s) of the gene ALPL that encodes the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). TNSALP is a cell-surface homodimeric phosphomonoester phosphohydrolase expressed in healthy people especially in the skeleton, liver, kidneys, and developing teeth. In HPP, diminished TNSALP activity leads to extracellular accumulation of its natural substrates including inorganic pyrophosphate (PPi), an inhibitor of mineralization, and pyridoxal 5'-phosphate (PLP), the principal circulating form of vitamin B6 (B6). Autosomal dominant and autosomal recessive inheritance involving >450 usually missense defects scattered throughout ALPL largely explains the remarkably broad-ranging severity of this inborn-error-of-metabolism. In 1985 when we identified elevated plasma PLP as a biochemical hallmark of HPP, all 14 investigated affected children and adults had markedly increased PLP levels. However, pyridoxal (PL), the dephosphorylated form of PLP that enters cells to cofactor many enzymatic reactions, was not low but often inexplicably elevated. Levels of pyridoxic acid (PA), the B6 degradation product quantified to assess B6 sufficiency, were unremarkable. Canonical signs or symptoms of B6 deficiency or toxicity were absent. B6-dependent seizures in infants with life-threatening HPP were later explained by their profound deficiency of TNSALP activity blocking PLP dephosphorylation to PL and diminishing gamma-aminobutyric acid synthesis in the brain. Now, there is speculation that altered B6 metabolism causes further clinical complications in HPP. Herein, we assessed the plasma PL and PA levels accompanying previously reported elevated plasma PLP concentrations in 150 children and adolescents with HPP. Their mean (SD) plasma PL level was nearly double the mean for our healthy pediatric controls: 66.7 (59.0) nM versus 37.1 (22.2) nM (P<0.0001), respectively. Their PA levels were broader than our pediatric control range, but their mean value was normal; 40.2 (25.1) nM versus 39.3 (9.9) nM (P=0.7793), respectively. In contrast, adults with HPP often had plasma PL and PA levels suggestive of dietary B6 insufficiency. We discuss why the B6 levels of our pediatric patients with HPP would not cause B6 toxicity or deficiency, whereas in affected adults dietary B6 insufficiency can develop.

Vitamin B6 deficiency with normal plasma levels of pyridoxal 5'-phosphate in perinatal hypophosphatasia.

Pyridoxal 5'-phosphate (PLP), the principal circulating form of vitamin B6 (B6), is elevated in the plasma of individuals with hypophosphatasia (HPP). HPP is the inborn-error-of-metabolism caused by loss-of-function mutation(s) of ALPL, the gene that encodes the "tissue-nonspecific" isoenzyme of alkaline phosphatase (TNSALP). PLP accumulates extracellularly in HPP because it is a natural substrate of this cell-surface phosphomonoester phosphohydrolase. Even individuals mildly affected by HPP manifest this biochemical hallmark, which is used for diagnosis. Herein, an exclusively breast-fed newborn boy with life-threatening perinatal HPP had uniquely normal instead of markedly elevated plasma PLP levels before beginning asfotase alfa (AA) TNSALP-replacement therapy. These abnormal PLP levels were explained by B6 deficiency, confirmed by his low plasma level of 4-pyridoxic acid (PA), the B6 degradation product. His mother, a presumed carrier of one of his two ALPL missense mutations, had serum ALP activity of 50U/L (Nl 40-130) while her plasma PLP level was 9 μg/L (Nl 5-50) and PA was 3 μg/L (Nl 3-30). Her dietary history and breast milk pyridoxal (PL) level indicated she too was B6 deficient. With B6 supplementation using a breast milk fortifier, the patient's plasma PA level corrected, while his PLP level remained in the normal range but now in keeping with AA treatment. Our experience reveals that elevated levels of PLP in the circulation in HPP require some degree of B6 sufficiency, and that anticipated increases in HPP can be negated by hypovitaminosis B6.

Gender Differences in the Associations of Plasma Pyridoxal 5'-Phosphate with Plasma Polyunsaturated Fatty Acids among US Young and Middle-Aged Adults: NHANES 2003-2004.

Vitamin B6-restricted diets and low plasma pyridoxal 5′-phosphate (PLP) status altered plasma polyunsaturated fatty acids (PUFA) compositions. Evidence suggests the role of gender in the metabolism of vitamin B6 and PUFA. However, no epidemiologic study examined the impact of gender on the relationship between vitamin B6 and PUFA status in adults. Thus, we investigated whether there were gender differences in the association of vitamin B6 intake and plasma PLP concentration with plasma PUFA concentrations and ratios (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA), EPA + DHA, EPA/AA, (EPA + DHA)/AA) in US young/middle-aged adults. In total, 864 participants (20–59 years; 484 men, 380 women) from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 were used for this cross-sectional study. Nutrient intakes were estimated from two 24 h recalls and supplement questionnaires; plasma PLP and PUFA were measured. Multivariate linear regression was utilized to obtain unstandardized (b) and standardized (β) coefficients. Covariates included demographic, socioeconomic, dietary variables, physical activity level, cigarette smoking status, alcohol consumption, prescription medication use, and BMI. There were significant interactions between gender and PLP on EPA (P-interaction = 0.004), DHA (P-interaction = 0.020), EPA + DHA (P-interaction = 0.010), EPA/AA (P-interaction = 0.002), (EPA + DHA)/AA (P-interaction = 0.004), whereas no interaction between gender and B6 intake existed. In gender-stratified analyses, in men, PLP was positively associated with EPA (β = 0.138, b = 0.104, p = 0.0004), DHA (β = 0.101, b = 0.058, p = 0.036), EPA + DHA (β = 0.125, b = 0.073, p = 0.005), EPA/AA (β = 0.144, b = 0.099, p = 0.0002), (EPA + DHA)/AA (β = 0.123, b = 0.068, p = 0.005). However, no associations between PLP and PUFA existed in women. In conclusion, gender differences were found in the relationships between plasma PLP and plasma EPA, DHA, EPA + DHA, EPA/AA, and (EPA + DHA)/AA, with significant direct associations in men only among US young/middle-aged adults.

In Vitro and In Vivo Pharmacological Profiles of DS-1211, a Novel Potent, Selective, and Orally Bioavailable Tissue-Nonspecific Alkaline Phosphatase Inhibitor.

Inhibition of tissue-nonspecific alkaline phosphatase (TNAP) may prevent ectopic soft tissue calcification by increasing endogenous pyrophosphate (PPi). DS-1211 is a potent and selective novel small molecule TNAP inhibitor with well-characterized pharmacokinetics (PKs) in rodent and monkey. Herein, we report a comprehensive summary of studies establishing the pharmaceutical profile of DS-1211. In vitro studies characterized the mode of inhibition and inhibitory effects of DS-1211 on three human alkaline phosphatase (ALP) isozymes-TNAP, human intestinal ALP, human placental ALP-and on ALP activity across species in mouse, monkey, and human plasma. In vivo PK and pharmacodynamic (PD) effects of a single oral dose of DS-1211 in mice and monkeys were evaluated, including biomarker changes in PPi and pyridoxal 5'-phosphate (PLP). Oral bioavailability (BA) was determined through administration of DS-1211 at a 0.3-mg/kg dose in monkeys. In vitro experiments demonstrated DS-1211 inhibited ALP activity through an uncompetitive mode of action. DS-1211 exhibited TNAP selectivity and potent inhibition of TNAP across species. In vivo studies in mice and monkeys after single oral administration of DS-1211 showed linear PKs, with dose-dependent inhibition of ALP activity and increases in plasma PPi and PLP. Inhibitory effects of DS-1211 were consistent in both mouse and monkey. Mean absolute oral BA was 73.9%. Overall, in vitro and in vivo studies showed DS-1211 is a potent and selective TNAP inhibitor across species. Further in vivo pharmacology studies in ectopic calcification animal models and clinical investigations of DS-1211 in patient populations are warranted. © 2022 Daiichi Sankyo, Inc. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Vitamin B6, Inflammation, and Cardiovascular Outcome in a Population-Based Cohort: The Prevention of Renal and Vascular End-Stage Disease (PREVEND) Study.

Background: a large number of studies have linked vitamin B6 to inflammation and cardiovascular disease in the general population. However, it remains uncertain whether vitamin B6 is associated with cardiovascular outcome independent of inflammation. Methods: we measured plasma pyridoxal 5’-phosphate (PLP), as an indicator of vitamin B6 status, at baseline in a population-based prospective cohort of 6249 participants of the Prevention of Renal and Vascular End-stage Disease (PREVEND) study who were free of cardiovascular disease. As indicators of low-grade systemic inflammation, we measured high-sensitivity C-reactive protein and GlycA; Results: median plasma PLP was 37.2 (interquartile range, 25.1–57.0) nmol/L. During median follow-up for 8.3 (interquartile range, 7.8–8.9) years, 409 non-fatal and fatal cardiovascular events (composite outcome) occurred. In the overall cohort, log transformed plasma PLP was associated with the composite outcome, independent of adjustment for age, sex, smoking, alcohol consumption, body mass index (BMI), estimated glomerular filtration rate (eGFR), total cholesterol:high-density lipoprotein (HDL)-cholesterol ratio, and blood pressure (adjusted hazard ratio per increment of log plasma PLP, 0.66; 95% confidence interval (CI), 0.47–0.93). However, adjustment for high-sensitivity C-reactive protein and GlycA increased the hazard ratio by 9% and 12% respectively, to non-significant hazard ratios of 0.72 (95% confidence interval, 0.51–1.01) and 0.74 (95% confidence interval, 0.53–1.05). The association of plasma PLP with cardiovascular risk was modified by gender (adjusted Pinteraction = 0.04). When stratified according to gender, in women the prospective association with cardiovascular outcome was independent of age, smoking, alcohol consumption, high-sensitivity C-reactive protein, and GlycA (adjusted hazard ratio, 0.50, 95% confidence interval, 0.27–0.94), while it was not in men (adjusted hazard, 0.99, 95% confidence interval, 0.65–1.51). Conclusions: in this population-based cohort, plasma PLP was associated with cardiovascular outcome, but this association was confounded by traditional risk factors and parameters of inflammation. Notably, the association of low plasma PLP with high risk of adverse cardiovascular outcome was modified by gender, with a stronger and independent association in women.

Vitamin B6 Supplementation Reduces Depression in College Women Taking Oral Contraceptives: A Randomized, Double-Blind Cross-Over Trial

Abstract Objectives Oral contraception (OC) use has been linked to an increased risk of depression in college women and to poor micronutrient status. Of note, when compared to non-OC users, OC users have a heightened risk of low plasma concentrations of vitamin B6, a cofactor in the tryptophan-serotonin pathway critical to mood regulation. The purpose of this crossover study was to determine whether vitamin B6 supplementation impacted mood states and depression in college women using OC. Methods Participants were healthy and between 18–25 y, did not smoke or use dietary supplements, and used OC (estrogen with progestin) consistently for at least one year prior to the start of the study. The 12-week, randomized, double-blind crossover trial (4-week treatment periods [B6: 100 mg/d or control: placebo pill/d] separated by a 4-week washout [no pills taken]) was approved by the university Institutional Review Board, and participants provided written consent. Anthropometric measures, blood sampling, and diet and mood assessments were completed at the start of the trial and at weeks 4, 8, and 12. Participants (n = 8) maintained normal exercise and eating patterns the duration of the study and recorded pill consumption daily. The Profile of Mood States (POMS) and Beck Depression Inventory were used to assess affect. Plasma pyridoxal 5′ phosphate (PLP) concentrations were quantified by enzymatic assay. Repeated measures ANOVA was used to assess treatment effects. Results Plasma PLP concentrations averaged 66 ± 32 nmol/L at the start of the trial; one participant presented with marginal vitamin B6 status (20–30 nmol/L). Average vitamin B6 intakes did not vary during the trial (1.2–1.4 mg/d); whereas, vitamin B6 status rose significantly following the B6 supplementation period compared to the other three timepoints. POMS scores were not impacted by treatment; however, Beck Depression Inventory scores were reduced 30% by B6 supplementation in comparison to the control treatment (P = 0.047). Conclusions These preliminary data support a growing literature suggesting the benefits of B6 supplementation for reducing depression in young women using OC. Funding Sources This study was supported in part by the Graduate and Professional Students Association and the Office of the Vice Provost for Research.

Association of Polyunsaturated Fatty Acids and Vitamin B6 with Inflammation in Adults from the National Health and Nutrition Examination Survey (NHANES) 2003–2004

Abstract Objectives Polyunsaturated fatty acids (PUFA) such as n-3 PUFA, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and n-6 PUFA, arachidonic acid (AA) may mediate inflammatory responses. Vitamin B6 deficiency has been shown to alter plasma PUFA levels. This perturbation of PUFA metabolism in vitamin B6 deficiency measured by pyridoxal-5’-phosphate (PLP) may contribute to inflammation. Thus, we aimed to examine the associations of 1) dietary EPA + DHA, and vitamin B6 with plasma ratio of AA/(EPA + DHA) by PLP level, 2) plasma AA/(EPA + DHA) and PLP with C-reactive protein (CRP), a marker for inflammation, and 3) dietary EPA + DHA, and vitamin B6 with CRP level, using NHANES. Methods NHANES datasets (2003–2004) with subjects ≥20 years were analyzed, accounting for survey design and sample weights (n = 4486). The significance level was P &amp;lt; 0.05. Covariates were age, gender, ethnicity, BMI, smoking, alcohol, total energy, dietary supplements, physical activity, and NSAIDs, depending on analyses. Multiple linear regression assessed the association of dietary EPA + DHA, and vitamin B6 with plasma ratio of AA/(EPA + DHA) by PLP level (Low: &amp;lt; 20 nmol/L, High: ≥20 nmol/L). Next, multivariate logistic regression predicted the associations of plasma AA/(EPA + DHA) and PLP with CRP level (Low: ≤3 mg/L, Moderate to High: &amp;gt; 3 mg/L); then, dietary EPA + DHA, and B6 with CRP level. Results In the low PLP level, dietary EPA + DHA was negatively associated with plasma ratio of AA/(EPA + DHA) (B = ─5.29, SE = 0.84, P = &amp;lt; .0001), but B6 intake was not, whereas, in the high PLP level, both dietary EPA + DHA (B = ─2.99, SE = 0.53, P = &amp;lt; .0001) and dietary vitamin B6 (B = ─0.21, SE = 0.04, P = 0.0001) were inversely associated with plasma AA/(EPA + DHA). Further, low PLP level was associated with greater odds of moderate to high CRP level compared to high PLP level (adjusted OR (aOR): 2.8, 95% CI: 1.93–4.04, P = &amp;lt; .0001), but plasma AA/(EPA + DHA) was not. In addition, both dietary EPA + DHA (aOR: 0.5, 95% CI: 0.23–0.98, P = 0.04) and vitamin B6 (aOR: 0.8, 95% CI: 0.68–0.95, P = 0.009) were inversely associated with moderate to high CRP level. Conclusions Our findings show that low plasma PLP level and low vitamin B6 intake are associated with inflammation, and the relationship may be through their effect on PUFA metabolism, suggesting that increased intake of vitamin B6 and EPA and DHA may protect against inflammation. Funding Sources N/A.

SAT-375 A 59 Year Old Female with Isolated Vitamin B6 Deficiency and Muscle Spasms

IntroductionVitamins are essential micronutrients required by biological organisms in small quantities for maintaining basic cellular metabolism. Vitamin B6 is an important co-factor for many biochemical reactions in cellular metabolism related to the synthesis and catabolism of amino acids, fatty acids, neurotransmitters, and organelle-specific compounds, as well as in detoxifying reactive oxygen species within the cell. (1) Due to the role of Vitamin B6 in intracellular metabolism and synthesis of neurotransmitters, deficiency of the vitamin results in impaired transcellular signaling between neurons, and classically presents with muscular convulsions, hyperirritability, and peripheral neuropathy. (2)Case PresentationHistoryWe present a case of a 59-year old female with Type 2 diabetes who complained of muscle spasms. She experienced muscle spasms in her feet which have spread proximally to involve her legs. She also admitted to experiencing intermittent spasms in her left arm. The spasms occurred intermittently throughout the day and persist throughout the night, making it difficult for her to fall asleep. She had taken cyclobenzaprine twice daily and tried leg stretches, however her spasms persist. She had also tried baclofen in the past without significant alleviation of her symptoms.EvaluationAn extensive investigation was conducted including tests for water-soluble vitamins. Her plasma pyridoxal 5-phosphate was 3 mcg/L (reference range 5-50 mcg/L), confirming vitamin B6 deficiency. She was also tested for Vitamins B1, B3, B12 and folate. None of the respective tests indicated deficiencies. Other test results were within normal limits.TreatmentThe patient received standard-dose intramuscular vitamin B6 injections for three weeks followed by oral supplements for 3 months. She was also given cyclobenzaprine (10 mg tablet) three times a day for muscle spasms in her legs. Although she had reported cyclobenzaprine did not significantly alleviate her spasms per se, it produces a sedative effect which improves her tolerance to the spasms and helps her to fall asleep at night.ConclusionThis case illustrates the rare instance of isolated vitamin B6 deficiency with normal serum levels of other water-soluble vitamins, manifesting as myoclonic spasm involving the legs and arms in the absence of objective polyneuropathy.References i1 Parra, Marcelina, Seth Stahl, and Hanjo Hellmann. “Vitamin B6 and its role in cell metabolism and physiology.” Cells 7.7 (2018): 84. i2 Brown, Mary J., and Kevin Beier. “Vitamin B6 Deficiency (Pyridoxine).” StatPearls [Internet]. StatPearls Publishing, 2018.

Hereditary polyneuropathy with optic atrophy due to PDXK variant leading to impaired Vitamin B6 metabolism

PDXK encodes for a pyridoxal kinase, which converts inactive B6 vitamers to the active cofactor pyridoxal 5'-phosphate (PLP). Recently, biallelic pathogenic variants in PDXK were shown to cause axonal Charcot-Marie-Tooth disease with optic atrophy that responds to PLP supplementation. We present two affected siblings carrying a novel biallelic missense PDXK variant with a similar phenotype with earlier onset. After detection of a novel PDXK variant using Whole Exome Sequencing, we confirmed pathogenicity through in silico protein structure analysis, determination of pyridoxal kinase activity using liquid chromatography-tandem mass spectrometry, and measurement of plasma PLP concentrations using high performance liquid chromatography. Our in silico analysis shows a potential effect on PDXK dimer stability, as well as a putative effect on posttranslational ubiquitination that is predicted to lead to increased protein degradation. We demonstrate that the variant leads to almost complete loss of PDXK enzymatic activity and low PLP levels. Our patients' early diagnosis and prompt PLP replacement restored the PLP plasma levels, enabling long-term monitoring of clinical outcomes. We recommend that patients presenting with similar phenotype should be screened for PDXK mutations, as this is a rare opportunity for treatment.