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Leucine 7 to Proline 7 Polymorphism in the Neuropeptide Y Gene Is Associated with Enhanced Carotid Atherosclerosis in Elderly Patients with Type 2 Diabetes and Control Subjects¹

Departments of Clinical Nutrition (L.N., R.V., M.I.J.U.), Medicine (L.N., M.L.), and Physiology (R.R., J.T.), University of Kuopio, and Kuopio Research Institute of Exercise Medicine and Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital (R.R., J.T.), FIN-70211 Kuopio, Finland; Department of Pharmacology and Clinical Pharmacology, University of Turku (M.K.K., M.K., U.P.), FIN-20520 Turku, Finland; and Department of Endocrinology and Metabolism, Merck Research Laboratories, Merck & Co., Inc. (M.M.), Rahway, New Jersey 07065-0900

Address all correspondence and requests for reprints to: Leo Niskanen, M.D., Department of Medicine, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland. E-mail: leo.niskanen{at}kuh.fi

	Abstract

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We have recently demonstrated that subjects having Pro⁷ in the signal peptide of neuropeptide Y (NPY) have higher serum cholesterol and apolipoprotein B levels than individuals with wild-type (Leu⁷Leu⁷) signal peptide sequence. We investigated the association of Leu⁷Pro polymorphism with common carotid intima media thickness (IMT) assessed by ultrasonograph in patients with type 2 diabetes (n = 81; 41 men and 40 women; mean age, 67.1 yr) and nondiabetic subjects (n = 105; 48 men and 57 women; mean age, 65.5 yr) and genotyped for the Leu⁷Pro polymorphism in prepro-NPY. The frequency of Pro⁷ in prepro-NPY was 9.9% (8 of 81) in diabetic patients and 14.3% (15 of 105) in control subjects (P = 0.360). The mean common carotid IMT was 1.04 ± 0.02 mm in nondiabetic subjects without the Leu⁷Pro polymorphism and 1.14 ± 0.04 mm in nondiabetic subjects with in (P = 0.156) and 1.18 ± 0.03 and 1.58 ± 0.21 mm in diabetic patients without and with the Leu⁷Pro polymorphism (P = 0.004), respectively. In the analysis of covariance of the entire group, the mean common carotid IMT was independently associated with the Leu⁷Pro polymorphism (F = 5.165; P = 0.024) after adjustment for known risk factors. Thus, the presence of the Pro⁷ substitution in the prepro-NPY associates with increased carotid atherosclerosis.

	Introduction

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NEUROPEPTIDE Y (NPY) is a member of the pancreatic polypeptide family and neuromodulator; it is the most abundant peptide in the brain and heart (1, 2, 3, 4). NPY is the most potent orexigenic neuropeptide (2, 3, 5). In the cardiovascular system NPY is a vasoconstrictor, and it inhibits the release of norepinephrine and potentiates the norepinephrine response (6). Interestingly, in experimental diabetes cardiorespiratory responses to NPY have been shown to be altered (7, 8). Furthermore, NPY may have angiogenic properties (4) that could enhance the development of atherosclerosis. The widespread effects of NPY are mediated by several subtypes of NPY receptors (9). We recently identified a rather common leucine to proline substitution in codon 7 of the NPY gene (Leu⁷Pro) (10).This polymorphism was found to be associated with significantly higher serum total and low density lipoprotein (LDL) cholesterol levels, particularly in obese subjects in Finnish and Dutch study populations. When considering various effects of NPY, it is conceivable to test the hypothesis that the Leu⁷Pro polymorphism in the prepro-NPY gene could be a risk marker for atherosclerosis.

	Subjects and Methods

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Study design

This study was a cross-sectional analysis from the 10-yr examination of a cohort of patients with type 2 diabetes and nondiabetic control subjects followed up from the time of diagnosis, as described previously in detail (11, 12, 13, 14, 15, 16, 17). In brief, the original study comprised 133 patients with newly diagnosed type 2 diabetes, aged 45–64 yr, and 144 nondiabetic control subjects randomly selected from the population register. The baseline study was carried out during the years 1979–1981, and all subjects were collected from a defined area in eastern Finland (11). All of the subjects were invited for the 5- and 10-yr follow-up examinations during the years 1985–1986 (12) and 1991–1992 (13, 14), respectively. During the 10-yr follow-up, 36 (27%) diabetic patients and 8 (6%) nondiabetic subjects died, mainly due to cardiovascular diseases (13). At the 10-yr examination, carotid ultrasonographic examinations (15, 16) were performed on 84 (63%) of the original diabetic and 119 (83%) of the nondiabetic subjects, and genotyping for NPY was made for all of these subjects except for 3 diabetic patients and 1 nondiabetic subject. The study was approved by the ethics committee of the University of Kuopio.

The assessment of medical history and cardiovascular diseases, the use of medication, smoking, blood pressure, body mass index and waist to hip circumference ratio have been described in detail previously (11, 12, 13, 14, 15, 16, 17). The macrovascular disease refers to the group of subjects with any previously defined evidence of myocardial infarction, stroke, or intermittent claudication. An oral glucose tolerance test was performed using a glucose dose of 75 g. The glucose tolerance was classified according to WHO criteria (18). The collection of blood specimens and the measurement of serum lipid and lipoproteins by ultracentrifugation and precipitation methods, apolipoprotein B, plasma glucose, and plasma insulin have been previously reported (14, 15, 16, 17).

Genotype analysis

The prepro-NPY genotype was determined by restriction fragment length polymorphism analysis of DNA extracted from the subjects’ peripheral blood. Briefly, the polymorphism appears as a thymidine (1128) to cytosine (1128) substitution generating a BsiEI restriction site, which was used to genotype the subjects for the Leu⁷Pro polymorphism, as described previously (10) .The PCR products were digested by BsiEI (New England Biolabs, Inc., Beverly, MA), and digestions were analyzed by electrophoresis on 2% agarose gel.

Assessment of carotid atherosclerosis

The high resolution B-mode ultrasonographic imaging protocol was designed to ensure the valid and reliable identification of arterial carotid references and the definition of near wall and far wall interfaces, as described previously in more detail (15, 16, 19, 20). The mean maximum of the far wall bilaterally was used as the measurement of the common carotid intima media thickness (IMT).

Autonomic nervous system function tests

The methods used have been described previously in more detail (21). Briefly, frequency domain analysis of heart rate variation (HRV) was determined using spectral analysis of HRV. Spectral estimations of R peak intervals of QRS complexes (RR) interval variability were obtained from stationary regions of registrations. After detrending the signals (first degree), a least mean square autoregressive model with a model order of 18 was used to obtain a power spectral estimate of RR interval variability. Total power (variance) was divided into three frequency bands: low frequency band (LF; 0.0–0.07 Hz), medium frequency band (MF; 0.07–0.15 Hz), and high frequency band (HF; 0.15–0.50 Hz). Signal powers in the three frequency bands were calculated as integrals under the respective power spectral density function, and the MF/HF ratio was calculated. The power spectral analysis enables the simultaneous assessment of the sympathetic and parasympathetic components of autonomic nervous function. The HF component of spectral HRV is almost exclusively mediated by vagal activity, and the MFP component gives a measure of sympathetic activity with some influence from vagal activity. The MF/HF ratio is a measure of sympathovagal balance.

Statistical methods

Associations of Leu⁷Pro polymorphism with continuous variables were calculated using Student’s t test and with categorized variables by ² test. The association of common carotid IMT with the Leu⁷Pro polymorphism was further analyzed by analysis of covariance controlling for the effects of confounding variables.

	Results

Top Abstract Introduction Subjects and Methods Results Discussion References

 
The C1128 allele frequencies followed the expectations of the Hardy-Weinberg equilibrium. The frequency of the Leu⁷Pro⁷ genotype was not significantly different between nondiabetic (14.3%) and diabetic (9.9%; P = 0.36) subjects. The characteristics of nondiabetic and diabetic subjects for Leu⁷Leu⁷ and Leu⁷Pro⁷ groups are presented in Table 1, a and b. No differences in age, gender, body mass index, waist to hip ratios, blood pressure levels, or frequency of macrovascular disease were found between the genotype groups within the nondiabetic and diabetic groups. LDL cholesterol was higher in nondiabetic subjects with the Leu⁷Pro polymorphism than in those without (P = 0.05), as we have reported previously (15). Although apolipoprotein B levels tended to be higher in Leu⁷Pro⁷ group than in the Leu⁷Leu⁷ group, the difference was not statistically significant. Our previous study included only the lean subjects of the present nondiabetic group not taking antihypertensive medication (10). In other lipoproteins no evident differences were found, and interestingly, in diabetic patients there was no association with serum cholesterol in either lean or obese subjects, analyzed according to median body mass index (data not shown).

	Discussion

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Our findings based on elderly Finnish nondiabetic and diabetic subjects indicates that the Leu⁷Pro genotype in the prepro-NPY gene is associated with carotid atherosclerosis, even more markedly in diabetic patients. This finding is of importance, because an increase in the carotid IMT increases the risk for cardiovascular events in a linear fashion even before any clinical manifestations of cardiovascular diseases (22). The Leu⁷Pro genotype was also associated with high serum LDL cholesterol levels and apolipoprotein B levels in lean nondiabetic subjects (10), but this was not found in diabetic patients regardless of body weight. Interestingly, this NPY polymorphism seemed to modulate the sympathovagal balance of the autonomic nervous system.

Type 2 diabetes is characterized by a markedly increased risk of atherosclerosis. Although conventional risk factors contribute largely to the occurrence of macrovascular diseases in diabetic patients (23), a large proportion of this burden remains unexplained, and a search for other contributors is warranted. In this study we showed for the first time that diabetic patients with the Leu⁷Pro genotype have a greater carotid IMT than those with the Leu⁷Leu⁷ genotype. Although this finding was based on a limited number of subjects, the lack of association of the Leu⁷Pro⁷ genotype with other risk factors among the diabetic patients makes the finding more intriguing. In the analysis of combined groups, age, diabetes, systolic blood pressure, and clinical macrovascular disease were, as previously reported (16), powerful explanatory variables of carotid IMT. Interestingly, the effect of the Leu⁷Pro polymorphism persisted to be statistically significant. Other cardiovascular risk factors, except fasting insulin in nondiabetic subjects, were not associated with the Leu⁷Pro polymorphism in either group. The selective mortality may cause bias in the interpretation, as in any cross-sectional analysis. However, as LDL cholesterol levels were constantly higher during the entire 10-yr follow-up in lean nondiabetic control subjects with the Leu⁷Pro⁷ genotype, and, on the other hand, the genotype effect on carotid IMT was more marked in diabetic patients who had high cardiovascular mortality from the time of diagnosis (13), it is likely that this study should, if anything, underestimate the observed association.

Why, then, could NPY enhance the development of atherosclerosis? First, this effect may be mediated by the effects of the prepro-NPY genotype on LDL cholesterol level (10). However, this effect is modulated by body weight (10), and as judged from the present study, no effect was seen in type 2 diabetic patients. Second, NPY may have angiogenic properties that could be implicated in the development of atherosclerosis. NPY has been shown to act as a smooth muscle mitogen (24) and to stimulate attachment, migration, DNA synthesis (25), and the formation of capillary tubes by human endothelial cells (4). A minor proportion of circulating NPY level is derived from endothelial cells, and this endothelially derived NPY may act as an autocrine angiogenic factor even at very low concentrations (4). Third, NPY is an important modulator of the autonomic nervous system (7). Autonomic nervous dysfunction is an independent predictor of cardiovascular mortality in patients with type 2 diabetes, as demonstrated from this study population (17). Indeed, in diabetic patients this polymorphism was an independent determinant of sympathovagal balance (MF/HF ratio). Therefore, we suggest that atherosclerosis may be associated with the gene(s) involved in vascular development, lipid metabolism, and autonomic nervous function. The recently found gene variant (10) of the NPY gene is the first one in this respect shown to be related to accelerated atherosclerosis.

	Footnotes

 
¹ This work was supported by a grant from Kuopio University Hospital (to L.N.), grants from Finnish Cultural Foundation and Finnish Medical Society Duodecim (to M.K.K.), University Central Hospital of Turku, Finland (to M.K.), grants from the Ministry of Education in Finland and from the City of Kuopio (to R.R.), and grants from the Finnish Foundation for Diabetes Research, Kuopio University Hospital, and the Academy of Finland (to M.I.J.U.).

Received December 7, 1999.

Revised March 13, 2000.

Accepted March 13, 2000.

	References

Top Abstract Introduction Subjects and Methods Results Discussion References

 

1. Benarroch EE. 1994 Neuropeptides in the sympathetic system: presence, plasticity, modulation, and implications. Ann Neurol. 36:6–13.[CrossRef][Medline]
2. Tomaszuk A, Simpson C, Williams G. 1996 Neuropeptide Y, the hypothalamus and the regulation of energy homeostasis. Horm Res. 46:53–58.[Medline]
3. Palmiter RD, Erickson JC, Hollopeter G, Baraban SC, Schwatrz MW. 1998 Life without neuropeptide Y. Recent Prog Horm Res. 53:163–199.
4. Zukowska-Grojec Z, Karwatowska-Prokopczuk E, Rose W, et al. 1998 Neuropeptide Y: a novel angiogenic factor from the sympathetic nerves and endothelium. Circ Res. 83:187–195.[Abstract/Free Full Text]
5. Sahu A, Sninsky CA, Kalra SP. 1997 Evidence that hypothalamic neuropeptide Y gene expression and NPY levels in the paraventricular nucles increase before the onset of hyperphagia in experimental diabetes. Brain Res. 1997 755:339–342.
6. Shine J, Potter EK, Biden T, Selbie LA, Herzog H. 1994 Neuropeptide Y and regulation of the cardiovascular system. J Hypertens. 12(Suppl):S41–S45.
7. Dunbar JC, Ergene E, Anderson GF, Barraco RA. 1992 Decreased cardiorespiratory effects of neuropeptide Y in the nucleus tractus solitarius in diabetes. Am J Physiol. 262:R865–R8671.
8. Lind H, Erlinge D, Brunkwall J, Edvinsson L. 1995 Selective attenuation of neuropeptide-Y-mediated contractile responses in blood vessels from patients with diabetes mellitus. Clin Auton Res. 5:191–197.[CrossRef][Medline]
9. Larhammar D, Söderberg C, Lundell I. 1998 Evolution of the neuropeptide Y family and its receptors. Ann NY Acad Sci. 839:35–40.[CrossRef][Medline]
10. Karvonen MK, Pesonen U, Koulu M, et al. 1998 Association of a leucine(7)-to-proline(7) polymorphism in the signal peptide of neuropeptide Y with high serum cholesterol and LDL cholesterol levels. Nat Med. 4:1434–1437.[CrossRef][Medline]
11. Uusitupa M, Siitonen O, Aro A, Pyörälä K. 1985 Prevalence of coronary heart disease, left ventricular failure and hypertension in middle-aged, newly diagnosed type 2 (non-insulin-dependent) diabetic subjects. Diabetologia. 28:22–27.[CrossRef][Medline]
12. Niskanen LK, Uusitupa MI, Sarlund H, Siitonen O, Pyörälä K. 1990 Five-year follow-up study on plasma insulin levels in newly diagnosed NIDDM patients and nondiabetic subjects. Diabetes Care. 13:41–48.[Abstract]
13. Uusitupa MIJ, Niskanen LK, Siitonen O, Voutilainen E, Pyörälä K. 1993 Ten-year cardiovascular mortality in relation to risk factors and abnormalities in lipoprotein composition in type 2 (non-insulin-dependent) diabetic and non-diabetic subjects. Diabetologia. 36:1175–1184.[CrossRef][Medline]
14. Niskanen L, Uusitupa M, Karjalainen J, Siitonen O. 1994 Metabolic evolution of type 2 diabetes: 10-year follow-up study. J Intern Med. 236:263–270.[Medline]
15. Uusitupa M, Niskanen L, Luoma J, Mercouri M, Rauramaa R, Ylä-Herttuala S. 1996 Autoantibodies against oxidized LDL as predictors of atherosclerotic vascular disease in non-insulin-dependent diabetes mellitus. Arterioscler Thromb Vasc Biol. 16:1236–1242.[Abstract/Free Full Text]
16. Niskanen L, Rauramaa R, Miettinen H, Haffner SM, Mercuri M, Uusitupa M. 1996 Carotid artery intima-media thickness in elderly patients with NIDDM and in nondiabetic subjects. Stroke. 27:1986–1992.[Abstract/Free Full Text]
17. Töyry J, Niskanen L, Mäntysaari M, Länsimies E, Uusitupa M. 1996 Occurrence, predictors, and clinical significance of autonomic neuropathy in NIDDM: 10-year follow-up from the diagnosis. Diabetes. 45:308–315.[Abstract]
18. WHO. Diabetes mellitus: report of a WHO Study Group. Geneva: WHO; Tech Rep Ser no. 727; 1985.
19. Mercuri M, Bond MG, Nichols FT, Carr AA, Flack JM, Byington R, Raines J, for the MIDAS Group. 1993 Baseline reproducibility of B-mode ultrasound imaging measurements of carotid intimal media thickness: the Multicenter Isradipine Diuretic Atherosclerosis Study (MIDAS). J Cardiovasc Diagnosis Procedures. 11:241–252.
20. Rauramaa R, Väisänen S, Mercuri M, Rankinen T, Penttilä I, Bond MG. 1994. Association of risk factors and body iron status to carotid atherosclerosis in middle-aged eastern Finnish men. Eur Heart J. 15:1020–1027.
21. Töyry JP, Niskanen LK, Mäntysaari MJ, Länsimies EA, Haffner SM, Miettinen HJJ, Uusitupa MIJ. 1997 Do high proinsulin and C-peptide levels play a role in autonomic nervous dysfunction? Power spectral analysis in patients with non-insulin-dependent diabetes and nondiabetic subjects? Circulation96 :1185–1191.
22. O’Leary DH, Polak JF, Kronmal RA, Manolio TA, Burke GL, Wolfon SKJ. 1999 Carotid-artery intima and media thickness as a risk factor for myocardial infarction and stroke in older adults. Cardiovascular Health Study Collaborative Research Group. N Engl J Med. 340:14–22.[Abstract/Free Full Text]
23. Stamler J, Vaccaro O, Neaton JD, Wentworth D for the Multiple Risk Factor Intervention Trial Research Group. 1993 Diabetes, other risk factors and 12-years cardiovascular mortality for men screened in the Multiple Risk Factor Intervention Trial. Diabetes Care. 16:434–444.[Abstract]
24. Zukowska-Grojec Z, Pruszczyk P, Colton C, Yao J, Shen GH, Myers AK, Wahlestedt C. 1993 Mitogenic effect of neuropeptide Y in rat vascular smooth muscle cells. Peptides. 14:263–268.[CrossRef][Medline]
25. Shigeri Y, Fujimoto M. 1993 Neuropeptide Y stimulates DNA synthesis in vascular smooth muscle cells. Neurosci Lett. 149:19–21.[CrossRef][Medline]

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