n ovel biomarkers of b6-status and their relation to inflammation
DESCRIPTION
N ovel biomarkers of B6-status and their relation to inflammation. B6 vitamers in serum/plasma. Metabolic markers. Reflect vitamin function in tissues Less affected by short-term vitamin intake and distribution Allow assessment of vitamin status during supplementation. - PowerPoint PPT PresentationTRANSCRIPT
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Novel biomarkers of B6-status and their relation to inflammation
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B6 vitamers
in
serum/plasma
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Metabolic markers
• Reflect vitamin function in tissues • Less affected by short-term vitamin intake and distribution • Allow assessment of vitamin status during
supplementation
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Metabolic markers
• Cystathionine
• Creatine
• 3-Hydroxykynurenine (HK)
• HK/XA ratio
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Cystathionine
and
vitamin B6
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Kynurenines
and
vitamin B6
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3-Hydroxykynurenine (HK) and B6 status
From Midttun et al (2011) J Nutr 141: 611
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3-Hydroxykynurenine (HK) as a marker of B6 status
• A plausible mechanism in the sense that further metabolism of HK but not formation is dependent on PLP
• Inflexion point at about 20 nmol/L PLP in a population including subjects with high inflammatory status
• HK was more strongly associated with several inflammatory markers than with PLP
• A marked reduction in HK after pyridoxine supplementation
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HK/XA and other ratios and B6 status
From Ulvik et al (2013) Am J Clin Nutr 98: 934
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HK/XA and other ratios and B6 status
From Ulvik et al (2013) Am J Clin Nutr 98: 934
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Dose-response for HK and HK/XA ratio versus PLP
From Ulvik et al (2013) Am J Clin Nutr 98: 934
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HK/XA ratio as a marker of B6 status
• Compared to HK, HK/XA (and other ratios) better discriminated subjects with low PLP
• PLP was the strongest predictor for HK/XA (and other ratios)
• Ratios have the advantage of eliminating influences shared by metabolites
• Associations with several variables, including inflammatory markers and kidney function, were attenuated.
• A marked reduction in HK/XA after pyridoxine supplementation
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Vitamin B6
species
in
serum/plasma
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The vitamer B6 ratio, PAr• PAr = PA/(PLP+PL)
• PAr has a higher ICC (of 0.75) than any other ratio and B6 vitamer
• ICC of PAr was less affected by pyridoxine supplementation (reduced to 0.44) than ICC of any other ratio and B6 vitamer
• Inflammatory markers (CRP +WBC+KTR+neopterin) accounted for > 90% of the explained variance of PAr.
• Renal function (eGFR) has a strong impact on PA but only minor impact on PAr.
• In ROC analysis, PAr discriminated high inflammatory levels assessed by a summary score (>95th percentile) with an area under the curve of 0.85.
• Change in PAr over 28 days correlated with change in inflammatory markers over this time period
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ROC plot for the diagnostic accuracy of PAr (solid line) and PLP (dashed line) to detect high (> 95th percentile) summary score of CRP, neopterin and KTR
Ulvik et al (2014) Am J Clin Nutr,
accepted
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