Matrix Gla Protein Species and Risk of Cardiovascular Events in Type 2 Diabetic Patients
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Cardiovascular and Metabolic Risk ORIGINAL ARTICLE Matrix Gla Protein Species and Risk of Cardiovascular Events in Type 2 Diabetic Patients 1 3 GEERTJE W. DALMEIJER, PHD W.M. MONIQUE VERSCHUREN, PHD reduced coronary artery calcification and 1 3 YVONNE T. VAN DER SCHOUW, PHD JOLANDA M.A. BOER, PHD – 2 1 reduced risk of CVD (6 9). These effects ELKE J. MAGDELEYNS, BSC JOLINE W.J. BEULENS, PHD 2 are thought to be mediated by increased CEES VERMEER, PHD activation of MGP (10). MGP exists as various species, which OBJECTIVEd differ in their state of phosphorylation To investigate the relationship of circulating matrix Gla protein (MGP) species or carboxylation: phosphorylated, non- with incident cardiovascular disease (CVD) or coronary heart disease (CHD) in type 2 diabetic phosphorylated (desphospho-MGP patients. [dpMGP]), carboxylated (cMGP), or un- RESEARCH DESIGN AND METHODSdEPIC-NL is a prospective cohort study among carboxylated (ucMGP). Total uncarboxy- 40,011 Dutch men and women. At baseline (1993–1997), 518 participants were known to have lated MGP (t-ucMGP) is thought to be type 2 diabetes. MGP levels were measured by ELISA techniques in baseline plasma samples. The the sum of desphospho-uncarboxylated incidence of fatal and nonfatal CVD and CVD subtypesdCHD, peripheral arterial disease (PAD), MGP (dp-ucMGP) and phosphorylated- d heart failure, and stroke were obtained by linkage to national registers. Cox proportional uncarboxylated MGP (p-ucMGP) and hazard models were used to calculate hazard ratios (HRs), adjusted for sex, waist-to-hip ratio, mainly consists of p-ucMGP. physical activity, and history of CVD. Development of assays to measure RESULTSdDuring a median 11.2 years of follow-up, 160 cases of CVD were documented. circulating MGP species enabled the in- Higher circulating desphospho-uncarboxylated MGP (dp-ucMGP) levels were significantly as- vestigation of these species in the circula- – sociated with higher risk of CVD, with an HR per SD (HRSD)of1.21(95%CI1.06 1.38), PAD tion (11). These studies have shown that – – (HRSD 1.32 [95% CI 1.07 1.65]), and heart failure (HRSD 1.75 [95% CI 1.42 2.17]) after dp-ucMGP is a marker for vitamin K sta- adjustment. Higher circulating dp-ucMGP levels were not related to risk of CHD (HRSD 1.12 tus, with high dp-ucMGP level reflecting a – – [95% CI 0.94 1.34]) or stroke (HRSD 1.05 [95% CI 0.73 1.49]). Circulating desphospho- low vitamin K status (12–17). In line with carboxylated MGP and circulating total-uncarboxylated MGP levels were not associated with these results, several studies indeed showed CVD or CVD subtypes. that high dp-ucMGP levels were associated CONCLUSIONSdHigh dp-ucMGP levels were associated with increased CVD risk among with more calcification, though not consis- type 2 diabetic patients, especially with the subtypes PAD and heart failure, while other MGP tently (13,16,18,19). Theoretically, dp- species were not related to CVD risk. These results suggest that a poor vitamin K status is cMGP forms the mirror image of dp-ucMGP associated with increased CVD risk. and is hypothesized to be associated with lower calcification, but results from human, – Diabetes Care 36:3766 3771, 2013 observational studies are inconsistent (16,20). Finally, in cross-sectional studies, oronary artery calcification is an 1) regulation of calcification by vascular high t-ucMGP has been associated with de- independent predictor of cardiovas- smooth muscle cell (VSMC)-derived matrix creased calcification (16,21–23). C fi cular disease (CVD) (1). Matrix Gla vesicles and apoptotic body, 2) inhibition of Although vascular calci cation may protein (MGP) is a vitamin K–dependent calcium-phosphate precipitation, and 3)in- not be causally related to CVD, it has protein and a potent inhibitor of vascular hibition of VSMC trans differentiation (4). emerged as a strong and independent risk calcification (2). The importance of MGP Vitamin K is required for the function of marker for CVD (1), but the association of for vascular health has been demon- MGP through its role as a cofactor for MGP species with CVD events has not strated in MGP-deficient animals, who the enzyme g-glutamyl carboxylase, cat- been investigated to date. Diabetes is as- all died of massive arterial calcification alyzing the carboxylation of glutamic acid sociated with severe cardiovascular com- within 6–8 weeks after birth (3). The cel- residues (Glu) into g-carboxyglutamate plications, including vascular calcification lular and molecular mechanisms by (Gla) at five well-defined places in the and accelerated atherosclerosis, leading to which MGP prevents ectopic calcium de- protein (5). Human studies showed that increased morbidity and mortality in dia- position are multifaceted, including high vitamin K intake is associated with betic patients (24–27) Therefore, we performed a prospective study to investi- ccccccccccccccccccccccccccccccccccccccccccccccccc gate the association between circulating From the 1Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the MGP species and CVD or coronary heart Netherlands; 2VitaK, Maastricht University, Maastricht, the Netherlands; and the 3National Institute for disease (CHD) risk among a high-risk Public Health and the Environment, Bilthoven, the Netherlands. population, i.e., type 2 diabetic patients. Corresponding author: Geertje W. Dalmeijer, [email protected]. Received 9 January 2013 and accepted 17 May 2013. DOI: 10.2337/dc13-0065 RESEARCH DESIGN AND © 2013 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/ METHODSdThe EPIC-NL cohort is licenses/by-nc-nd/3.0/ for details. the Dutch contribution to the European 3766 DIABETES CARE, VOLUME 36, NOVEMBER 2013 care.diabetesjournals.org Dalmeijer and Associates Prospective Investigation into Cancer and assay is based on the use of detection (Bosch & Son, Jungingen, Germany) Nutrition (EPIC) and consists of the monoclonal antibody directed against (Prospect-EPIC) or on the left arm using Prospect-EPIC and MORGEN-EPIC co- the ucMGP sequence 35–49 in human a random zero sphygmomanometer horts (28). The Prospect-EPIC study in- MGP (mAb-ucMGP; VitaK BV), while (MORGEN-EPIC), from which the mean cludes 17,357 women 49–70 years of age for dp-cMGP this was directed against was taken. Height and weight were mea- living in Utrecht and vicinity who partic- the cMGP sequence 35–54 in human sured, and BMI was calculated. Time ipated in the nationwide Dutch breast MGP (mAb-cMGP; VitaK BV). All mea- since diabetes diagnosis was calculated cancer screening program between 1993 surements were performed in duplicate, by subtracting the age of diagnosis from and 1997. The MORGEN-EPIC cohort and average values are given throughout theageatbaselineexamination.HbA1c consists of 22,654 men and women 21– this article. concentrations were measured in eryth- 64 years of age selected from random rocytes using an immunoturbidimetric samples of the Dutch population in three Outcome assessment latex test. All measurements were performed different towns. Participants were re- Morbidity follow-up data on CVD events according to standard operating procedures. cruited in both studies from 1993 to were obtained from the Dutch Centre for 1997. At baseline, a general and a food- Health Care Information, which holds a Data analysis frequency questionnaire were adminis- standardized computerized register of Participant characteristics are presented tered, and a physical examination was hospital discharge diagnoses. All diagno- as means with SDs or percentages. The performed for blood pressure measure- ses were coded according to the ICD-9. duration of follow-up was calculated as ments, anthropometry, and nonfasting Follow-up was complete until the first of the interval between date of study entry blood sampling. All participants provided January 2008. The database was linked to (1993–1997) and the occurrence of a car- informed consent before study inclusion. the cohort on the basis of birth date, sex, diovascular event, death, loss to follow- The study complies with the Declaration postal code, and general practitioner up, or 1 January 2008: whichever came of Helsinki and was approved by the in- with a validated probabilistic method first. stitutional board of the University Medical (30). Information on vital status was ob- Cox proportional hazard models Center Utrecht (Prospect) and the Medical tained through linkage with the munici- were used to calculate crude and adjusted Ethical Committee of The Netherlands Or- pal registries. Causes of death were hazard ratios (HRs) and 95% CIs for the ganization for Applied ScientificResearch collected from Statistics Netherlands. associations between MGP species (con- Nutrition and Food Research (MORGEN). End points for the present analysis were tinuous) and CVD or CVD subtypes. Three sources of ascertainment of CVD and the subtypes CHD, peripheral Potential confounding factors (age, sex, diabetes were used: self-report, hospital arterial disease (PAD), heart failure, and BMI, waist-to-hip ratio, smoking habits, discharge diagnoses, and urinary strip test stroke. CVD was defined as CHD, PAD, physical activity, education, systolic and (in the Prospect part of the cohort only). heart failure, and stroke (CVD, 410–414, diastolic blood pressure, and total cho- Potential cases of diabetes ascertained 427.5, 428, 415.1, 443.9, 430–438, 440– lesterol) were selected based on univari- by these sources were verified against 442, 444, 798.1, 798.2, and 798.9; CHD, able associations of potential confounders medical and pharmacy records. Details 410–414, 427.5, 798.1, 798.2, and with both CVD or CVD subtypes and of the ascertainment sources and verifi- 798.9; PAD, 440–444; heart failure, MGP species and whether adjustment cation procedures have previously been 428; and stroke, 430–434 and 436). for the confounder changed the HR described (29).