title: Correlations of Plasma Desphosphorylated Uncarboxylated Matrix Gla Protein with Vascular Calcification and Vascular Stiffness in Chronic Kidney Disease.
abstract: BACKGROUND
  Matrix Gla protein (MGP) is a potent inhibitor of vascular calcification and needs vitamin K-dependent carboxylation for its activity. High levels of desphosphorylated uncarboxylated MGP (dp-ucMGP) were significantly associated with vitamin K deficiency and vascular calcification. This study was conducted to explore the correlations of plasma dp-ucMGP with vascular calcification and vascular stiffness in chronic kidney disease (CKD) patients.
  
  
  METHODS
  This cross-sectional study enrolled 83 CKD stages 3-5 patients. Vascular calcification score was determined by calcific lesions in the abdominal aorta (AAC) shown by lateral lumbar film; vascular stiffness was assessed by cardio-ankle vascular index (CAVI) and pulse wave velocity, while plasma dp-ucMGP levels were measured using ELISA method. Multivariate regression analyses were used to select factors that were independently associated with vascular calcification and vascular stiffness.
  
  
  RESULTS
  The mean age was 62.9 ± 13.9 years. CKD stages 3, 4, and 5 constituted 51.8, 13.3, and 34.9%, respectively. The median of plasma dp-ucMGP levels in CKD stages 3, 4, and 5 were 586 (452-888), 870 (594-1,591), and 1,050 (518-1,298) pmol/L, respectively. The prevalence of vascular calcification (AAC score ≥1) was 63.4% and that of vascular stiffness (CAVI ≥9) was 46.3%. Vascular calcification was correlated with vascular stiffness (r2 = 0.50, p < 0.001). Multivariate logistic regression analysis models to predict vascular calcification showed that age and plasma dp-ucMGP levels were significantly correlated with vascular calcification (OR 1.21; 95% CI 1.09-1.33; p < 0.001 and OR 1.002; 95% CI 1.001-1.004; p = 0.004, respectively). In contrast, there was no association between plasma dp-ucMGP levels and vascular stiffness.
  
  
  CONCLUSIONS
  Plasma dp-ucMGP levels increase according to the severity of CKD. Plasma dp-ucMGP was positively associated with vascular calcification and might be utilized as an early marker for vascular calcification in CKD patients.
authors.affiliation: Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Sipanan
authors.initials: S
authors.lastname: Thamratnopkoon
authors.forename: Paweena
authors.initials: P
authors.lastname: Susantitaphong
authors.forename: Monravee
authors.initials: M
authors.lastname: Tumkosit
authors.forename: Pisut
authors.initials: P
authors.lastname: Katavetin
authors.forename: Khajohn
authors.initials: K
authors.lastname: Tiranathanagul
authors.forename: Kearkiat
authors.initials: K
authors.lastname: Praditpornsilpa
authors.forename: Somchai
authors.initials: S
authors.lastname: Eiam-Ong
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002135:Calcium-Binding Proteins / Q000097:blood*; D003430:Cross-Sectional Studies; D016326:Extracellular Matrix Proteins / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010766:Phosphorylation; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000150:complications*; D061205:Vascular Calcification / Q000097:blood* / Q000150:complications; D059289:Vascular Stiffness / Q000502:physiology*; D014813:Vitamin K Deficiency / Q000097:blood / Q000150:complications; D000097568:Matrix Gla Protein
chemical_list: D015415:Biomarkers; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D000097568:Matrix Gla Protein