In vivo vitamin C supplementation increases phosphoinositol transfer protein expression in peripheral blood mononuclear cells from healthy individuals

• Published in: British journal of nutrition Vol. 101; no. 10; pp. 1432 - 1437
• Main Authors: Griffiths, Helen R, Willetts, Rachel S, Grant, Melissa M, Mistry, Nalini, Lunec, Joe, Bevan, Ruth J
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 28.05.2009
• Subjects: administration & dosage; Adult; analysis; Analysis of Variance; apoptosis; Apoptosis - drug effects; Ascorbic acid; Ascorbic Acid - administration & dosage; Ascorbic Acid - analysis; Ascorbic Acid - blood; Biological and medical sciences; Biomarkers; Biomarkers - analysis; Biosynthesis; blood; Blotting, Western; Blotting, Western - methods; carbohydrate metabolism; Caspase 3; Caspase 3 - analysis; chemistry; Collagen; diet therapy; Dietary Supplements; Double-Blind Method; drug effects; Electrophoresis, Polyacrylamide Gel; Electrophoresis, Polyacrylamide Gel - methods; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; gene expression regulation; Humans; Immune response; immunity; Intracellular Space; Intracellular Space - chemistry; Leukocytes; Leukocytes - chemistry; metabolism; methods; nutrient intake; nutritive value; oxidants; patients; Peripheral blood mononuclear cells; phosphatidylinositols; Phosphoinositol transfer protein; Phospholipid Transfer Proteins; Phospholipid Transfer Proteins - analysis; Phospholipid Transfer Proteins - metabolism; Plasma; Potassium; Potassium - blood; Protein expression; protein synthesis; Proteins; Proteomics; redox potential; redox reactions; reducing agents; T-lymphocytes; T-Lymphocytes - chemistry; T-Lymphocytes - drug effects; T-Lymphocytes - metabolism; transcription (genetics); Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin C; vitamin supplements; Young Adult; United Kingdom > UK; Human; Ascorbic acid; Phosphoinositol transfer protein; Gene expression; Protein; In vivo; Vertebrata; Blood cell; Mammalia; Mononuclear cell; Proteomics; Transfer; Peripheral blood mononuclear cells; Supplementation
• ISSN: 0007-1145; 1475-2662; 1475-2662
• DOI: 10.1017/S0007114508079646

Ascorbate can act as both a reducing and oxidising agent in vitro depending on its environment. It can modulate the intracellular redox environment of cells and therefore is predicted to modulate thiol-dependent cell signalling and gene expression pathways. Using proteomic analysis of vitamin C-treated T cells in vitro, we have previously reported changes in expression of five functional protein groups associated with signalling, carbohydrate metabolism, apoptosis, transcription and immune function. The increased expression of the signalling molecule phosphatidylinositol transfer protein (PITP) was also confirmed using Western blotting. Herein, we have compared protein changes elicited by ascorbate in vitro, with the effect of ascorbate on plasma potassium levels, on peripheral blood mononuclear cell (PBMC) apoptosis and PITP expression, in patients supplemented with vitamin C (0-2 g/d) for up to 10 weeks to investigate whether in vitro model systems are predictive of in vivo effects. PITP varied in expression widely between subjects at all time-points analysed but was increased by supplementation with 2 g ascorbate/d after 5 and 10 weeks. No effects on plasma potassium levels were observed in supplemented subjects despite a reduction of K+ channel proteins in ascorbate-treated T cells in vitro. Similarly, no effect of vitamin C supplementation on PBMC apoptosis was observed, whilst ascorbate decreased expression of caspase 3 recruitment domain protein in vitro. These data provide one of the first demonstrations that proteomics may be valuable in developing predictive markers of nutrient effects in vivo and may identify novel pathways for studying mechanisms of action in vivo.