Acute in vivo effects of insulin on gene expression in adipose tissue in insulin-resistant and insulin-sensitive subjects

AIMS/HYPOTHESIS

We determined the response of selected genes to in vivo insulin in adipose tissue in 21 non-diabetic women.

MATERIALS AND METHODS

The women were divided into insulin-sensitive and -resistant groups based on their median whole-body insulin sensitivity (8.7+/-0.4 vs 4.2+/-0.3 mg kg(-1) min(-1) for insulin-sensitive vs -resistant group). Subcutaneous adipose tissue biopsies were obtained before and after 3 and 6 h of i.v. maintained euglycaemic hyperinsulinaemia. Adipose tissue mRNA concentrations of facilitated glucose transporter, member 1 (SLC2A1, previously known as GLUT1), facilitated glucose transporter, member 4 (SLC2A4, previously known as GLUT4), peroxisome proliferator-activated receptor gamma ( PPARG), peroxisome proliferator-activated receptor gamma co-activator 1alpha (PPARGC1A), 11beta-hydroxysteroid dehydrogenase-1 (HSD11B1), TNF, adiponectin (ADIPOQ), IL6 and the macrophage marker CD68 were measured using real-time PCR.

RESULTS

Basal expression of 'insulin-sensitivity genes' SLC2A4 and ADIPOQ was lower while that of 'insulin-resistance genes', HSD11B1 and IL6 was significantly higher in the insulin-resistant than in the insulin-sensitive group. Insulin significantly increased expression of 'insulin-sensitivity genes' SLC2A4, PPARG, PPARGC1A and ADIPOQ in the insulin-sensitive group, while only expression of PPARG and PPARGC1A was increased in the insulin-resistant group. The expression of 'insulin-resistance genes' HSD11B1 and IL6 was increased by insulin in the insulin-resistant group, but insulin failed to increase HSD11B1 expression in the insulin-sensitive group. At 6 h, expression of HSD11B1, TNF and IL6 was significantly higher in the insulin-resistant than in the insulin-sensitive group. IL6 expression increased significantly more in response to insulin in the insulin-resistant than in the insulin-sensitive group. CD68 was overexpressed in the insulin-resistant as compared with the insulin-sensitive group at both 0 and 6 h.

CONCLUSIONS/INTERPRETATION

These data suggest that genes adversely affecting insulin sensitivity hyperrespond to insulin, while genes enhancing insulin sensitivity hyporespond to insulin in insulin-resistant human adipose tissue in vivo.

Treatment with combined oral contraceptives induces a rise in serum C-reactive protein in the absence of a general inflammatory response

BACKGROUND

The role of inflammation in the pathogenesis of cardiovascular disease is well established. C-reactive protein (CRP) is the strongest independent predictor of myocardial infarction and stroke in women. Recent studies have indicated that CRP levels are raised during use of combined oral contraceptives (COCs).

OBJECTIVES

The aim of the study was to investigate the effect of COCs on serum CRP levels and to indicate the underlying mechanisms of an expected increase.

METHOD

In a prospective randomized cross over-study 35 women used two different preparations of COC, one second and one third generation. Serum levels of CRP, serum amyloid A (SAA), interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha), antibodies against oxidized LDL, insulin and insulin-like growth factor-I (IGF-I) along with insulin-like growth factor binding protein-1 (IGFBP-1) and IGFBP-3 were analyzed before and during the two treatments. E-selectin, von Willebrand factor and factor VIII concentrations in plasma were also measured.

RESULTS

A rise in serum CRP was observed during both treatments; the median level increased from 0.45 mg L(-1) at baseline to 1.48 mg L(-1) with second generation and to 2.02 mg L(-1) with third generation COC. The serum levels of SAA increased slightly during treatment with the third generation COC. IL-6 and TNFalpha were unaffected by treatment. Both preparations lowered IGF-I and raised IGFBP-1 and IGFBP-3 concentrations.

CONCLUSION

The raised serum CRP concentration during treatment with COCs appears to be related to a direct effect on hepatocyte CRP synthesis and does not reflect IL-6 mediated inflammation, endothelial activation or induction of insulin resistance.

Beta cell dysfunction in patients with acute myocardial infarction but without previously known type 2 diabetes: a report from the GAMI study

AIMS/HYPOTHESIS

Patients with acute myocardial infarction (AMI) but without previously known type 2 diabetes have a high prevalence of undiagnosed IGT and type 2 diabetes. Such perturbations have dismal prognostic implications. The aim of this study was to characterise AMI patients in terms of insulin resistance and beta cell function.

METHODS

A total of 168 consecutive AMI patients were classified by means of an OGTT before hospital discharge as having NGT, IGT or type 2 diabetes. The homeostasis model assessment (HOMA-IR) was used to estimate insulin resistance. Beta cell responsiveness was quantified as insulinogenic index (IGI) at 30 min (DeltaI(30)/DeltaG(30)).

RESULTS

According to the HOMA-IR, patients with type 2 diabetes were more insulin resistant than those with IGT or NGT (p=0.003). Beta cell responsiveness deteriorated with decreasing glucose tolerance as measured by the IGI (median [quartile 1, quartile 3] in pmol/mmol: NGT, 70.1 [42.7, 101.4]; IGT, 48.7 [34.7, 86.8], type 2 diabetes, 38.1 [25.7, 61.6]; p<0.001). The IGI was significantly related to admission capillary blood glucose (r=-0.218, p=0.010) and to the area under the curve for glucose (r=-0.475, p<0.001).

CONCLUSIONS/INTERPRETATION

Glucose abnormalities are very common in patients with AMI but without previously known type 2 diabetes. To a significant extent, this seems to be related to impaired beta cell function and implies that dysglycaemia immediately after an infarction is not a stress epiphenomenon but reflects stable disturbances of glucose regulation preceding the AMI. Early beta cell dysfunction may have important pathophysiological implications and may serve as a future target for treatment strategies.

Serum matrix metalloproteinase-3 concentration is influenced by MMP-3 -1612 5A/6A promoter genotype and associated with myocardial infarction

OBJECTIVES

Matrix metalloproteinase-3 (MMP-3) is implicated in the formation of atherosclerotic plaques, and the MMP-3 -1612 5A/6A polymorphism is associated with myocardial infarction (MI) and stable coronary artery disease (CAD). The present study examined whether the -1612 5A/6A polymorphism in the promoter region of the MMP-3 gene influences serum concentrations of MMP-3 and whether serum concentrations of MMP-3 are related to extent of coronary atherosclerosis and risk of MI.

DESIGN AND SUBJECTS

This case-control study was conducted in three hospitals in the northern part of Stockholm. A total of 755 MI patients aged below 60 were screened, 433 entered and 387 completed the study. Three hundred and eighty-seven sex- and age-matched control subjects were recruited from the general population of the same county.

METHODS

The MMP-3 genotype was determined by Pyrosequencing(TM) and the serum MMP-3 concentration was quantified with an immunoassay. Severity and extension of CAD was assessed by quantitative coronary angiography in a subgroup of patients (n=243).

RESULTS

Patients had lower serum MMP-3 concentration than controls. There was a strong association between MMP-3 -1612 5A/6A genotype and serum concentrations of MMP-3. The presence of one or two copies of the 6A-allele was associated with a graded increase in serum MMP-3. In female patients there was an inverse correlation (r=-0.39, P<0.05) between serum MMP-3 concentration and plaque area. Conclusion. In conclusion, the serum concentration of MMP-3 is influenced by MMP-3 -1612 5A/6A genotype and associated with MI.

Genotype–phenotype relationships in an investigation of the role of proteases in abdominal aortic aneurysm expansion

Background

The aim of the study was to investigate the effect of functional polymorphisms in promoters of matrix metalloproteinase (MMP) 2, MMP-3, MMP-9, MMP-12 and plasminogen activator inhibitor (PAI) 1 genes on the growth rate of small abdominal aortic aneurysms (AAA).

Methods

Some 455 individuals with a small AAA (4·0–5·5 cm) were monitored for aneurysm growth by ultrasonography (mean follow-up 2·6 years). They also provided a DNA sample for analysis of the −1306 C &gt; T, −1171 5A &gt; 6A, −1562 C &gt; T, −82 A &gt; G and −675 4G &gt; 5G alleles of MMP-2, MMP-3, MMP-9, MMP-12 and PAI-1, respectively. Mean linear AAA growth rates were calculated by flexible modelling; the sample size was sufficient to detect variants that influenced the growth rate by 25 per cent.

Results

For MMP-2, MMP-9 and MMP-12 genotypes, growth rates were similar to the mean linear growth rate of 3·08 mm per year. For MMP-3, growth rates were 3·05 (for 5A5A), 3·19 (for 5A6A) and 2·90 (for 6A6A) mm per year. For PAI-1, patients with 4G4G, 4G5G and 5G5G genotypes had growth rates of 3·18, 2·92 and 3·47 mm per year, respectively, for aneurysms with a baseline diameter of 45·1, 44·6 and 46·2 mm. The increased growth rate for patients with PAI-1 5G5G genotype was not statistically significant (P = 0·061), although these patients had the lowest plasma PAI-1 concentrations (P = 0·018).

Conclusion

There was no evidence that any specific MMP polymorphism had a clinically significant effect on AAA expansion. The plasminogen system may have a small but clinically significant role in AAA development. Much larger studies would be needed to evaluate genes of smaller effect.

Intense metabolic control by means of insulin in patients with diabetes mellitus and acute myocardial infarction (DIGAMI 2): effects on mortality and morbidity

AIMS

Patients with diabetes have an unfavourable prognosis after an acute myocardial infarction. In the first DIGAMI study, an insulin-based glucose management improved survival. In DIGAMI 2, three treatment strategies were compared: group 1, acute insulin-glucose infusion followed by insulin-based long-term glucose control; group 2, insulin-glucose infusion followed by standard glucose control; and group 3, routine metabolic management according to local practice.

METHODS AND RESULTS

DIGAMI 2 recruited 1253 patients (mean age 68 years; 67% males) with type 2 diabetes and suspected acute myocardial infarction randomly assigned to groups 1 (n=474), 2 (n=473), and 3 (n=306). The primary endpoint was all-cause mortality between groups 1 and 2, and a difference was hypothesized as the primary objective. The secondary objective was to compare total mortality between groups 2 and 3, whereas morbidity differences served as tertiary objectives. The median study duration was 2.1 (interquartile range 1.03-3.00) years. At randomization, HbA1c was 7.2, 7.3, and 7.3% in groups 1, 2, and 3, respectively, whereas blood glucose was 12.8, 12.5, and 12.9 mmol/L, respectively. Blood glucose was significantly reduced after 24 h in all groups, more in groups 1 and 2 (9.1 and 9.1 mmol/L) receiving insulin-glucose infusion than in group 3 (10.0 mmol/L). Long-term glucose-lowering treatment differed between groups with multidose insulin (> or =3 doses/day) given to 15 and 13% of patients in groups 2 and 3, respectively compared with 42% in group 1 at hospital discharge. By the end of follow-up, HbA1c did not differ significantly among groups 1-3 ( approximately 6.8%). The corresponding values for fasting blood glucose were 8.0, 8.3, and 8.6 mmol/L. Hence, the target fasting blood glucose for patients in group 1 of 5-7 mmol/L was never reached. The study mortality (groups 1-3 combined) was 18.4%. Mortality between groups 1 (23.4%) and 2 (22.6%; primary endpoint) did not differ significantly (HR 1.03; 95% CI 0.79-1.34; P=0.831), nor did mortality between groups 2 (22.6%) and 3 (19.3%; secondary endpoint) (HR 1.23; CI 0.89-1.69; P=0.203). There were no significant differences in morbidity expressed as non-fatal reinfarctions and strokes among the three groups.

CONCLUSION

DIGAMI 2 did not support the fact that an acutely introduced, long-term insulin treatment improves survival in type 2 diabetic patients following myocardial infarction when compared with a conventional management at similar levels of glucose control or that insulin-based treatment lowers the number of non-fatal myocardial reinfarctions and strokes. However, an epidemiological analysis confirms that the glucose level is a strong, independent predictor of long-term mortality in this patient category, underlining that glucose control seems to be an important part of their management.

Interaction between the C-260T polymorphism of the CD14 gene and the plasma IL-6 concentration on the risk of myocardial infarction: the HIFMECH study

Experimental and clinical observations suggest that innate immunity plays a major role in the pathogenesis and progression of atherosclerosis. A common C-260T polymorphism in the promoter of the CD14 gene, the trans-membrane receptor of lipopolysaccharides, has been inconsistently associated with coronary heart disease. Our objective was to evaluate the contribution of the CD14 polymorphism to the inflammatory response and to the risk of myocardial infarction (MI). We used an European case-control study, the HIFMECH study, comparing 533 men with MI and 575 sex- and age-matched controls. Associations between genotype and disease outcome, according to interleukin-6 (IL-6) and C-reactive protein (CRP) levels, were assessed using conditional logistic regression. The CD14/C-260T polymorphism was associated with plasma IL-6 levels, T/T subjects having higher plasma levels than C/C in cases but not in controls (mean+/-S.D.: 2.04+/-1.37 versus 1.70+/-1.15, p=0.01; 1.20+/-0.75 versus 1.35+/-0.88, p=0.31, respectively). Overall, the CD14/C-260T polymorphism was not associated with the risk of MI. However, in individuals with IL-6 plasma levels in the highest tertile, T allele carriers had a higher risk of MI than C/C (OR: 1.85; CI 95 1.05-3.25). IL-6 increased the risk of MI in carriers of the T allele (OR for first versus third IL-6 tertile: 4.02; CI 95 2.24-7.21), but not in C/C (OR: 0.75; CI 95 0.32-1.74, p=0.004 for interaction). The data indicate a role for CD14/C-260T in MI. The risk mediated by the polymorphism is highly dependent on IL-6 plasma levels.

In the lipodystrophy associated with highly active antiretroviral therapy, pseudo-Cushing's syndrome is associated with increased regeneration of cortisol by 11beta-hydroxysteroid dehydrogenase type 1 in adipose tissue

AIMS/HYPOTHESIS

Highly active antiretroviral therapy (HAART) in patients infected with human immunodeficiency virus (HIV) is associated with a poorly understood lipodystrophic and hypertriglyceridaemic syndrome, which resembles Cushing's syndrome, but in which plasma cortisol is not elevated. We tested the hypothesis that this HAART-associated lipodystrophy is explained by increased local regeneration of cortisol from inactive cortisone within adipose tissue, catalysed by the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1).

METHODS

In this cross-sectional study, a previously described cohort of 30 HIV-infected patients with lipodystrophy were compared with 13 HIV-infected patients without lipodystrophy. Intra-abdominal and subcutaneous adipose tissue were quantified using magnetic resonance imaging. Gene expression in subcutaneous fat was measured using real-time PCR. Urine cortisol and its metabolites were analysed by gas chromatography/mass spectrometry.

RESULTS

Patients with lipodystrophy had significantly higher 11beta-HSD1 mRNA concentrations (relative to beta2-microglobulin mRNA) in subcutaneous adipose tissue than non-lipodystrophic patients (0.29+/-0.20 vs 0.09+/-0.07, p=0.0004) and higher ratios of urinary cortisol : cortisone metabolites. Adipose tissue 11beta-HSD1 mRNA correlated with multiple features of insulin resistance and with mRNA concentrations for glucocorticoid receptor and angiotensinogen.

CONCLUSIONS/INTERPRETATION

In adipose tissue of patients with HAART-associated lipodystrophy, 11beta-HSD1 mRNA is increased and its concentration is correlated with features of insulin resistance. We suggest that increased adipose tissue 11beta-HSD1 may explain the pseudo-Cushing's features in patients with HAART-associated lipodystrophy, and is a potential therapeutic target.

Abnormal glucose tolerance--a common risk factor in patients with acute myocardial infarction in comparison with population-based controls

BACKGROUND

A high prevalence of newly detected diabetes and impaired glucose tolerance (abnormal glucose tolerance) was recently reported in patients with acute myocardial infarction. It is important to verify whether this finding is specific for the patients or attributable to the population, from which they were recruited.

OBJECTIVE

To verify whether abnormal glucose tolerance is more prevalent in patients than in controls chosen from the same population and to compare metabolic characteristics between the two groups.

DESIGN AND SUBJECTS

The metabolic state was assessed in patients (n = 181) admitted with acute myocardial infarction and no history of diabetes before discharge and after 3 months. Sex- and age-matched controls (n = 185) without previously known diabetes or cardiovascular disease except hypertension were recruited from the general population.

MAIN OUTCOME MEASURES

Oral glucose tolerance test, glucosylated haemoglobin A1c (HbA1c), insulin, proinsulin, lipid profile, fibrinolytic function and inflammatory markers.

RESULTS

Abnormal glucose tolerance was more common (number/all classified) in patients at discharge 113/168 (67%) and after 3 months 95/145 (66%) than in controls 65/185 (35%) (P < 0.001). Dyslipidaemia (70% vs. 29%; P < 0.001) and previously treated hypertension (32% vs. 18%; P = 0.028) were more frequent amongst patients whilst obesity (18% vs. 24%) did not differ significantly. Blood glucose, HbA1c, proinsulin, proinsulin/insulin ratio, triglycerides, insulin resistance (by HOMA) and fibrinogen were consistently higher in patients than controls (P < 0.01).

CONCLUSIONS

Abnormal glucose tolerance was almost twice as common amongst patients with acute myocardial infarction as in matched controls. Impaired glycaemic control accompanied by insulin resistance, dyslipidaemia, hypertension, together with increased plasma fibrinogen and proinsulin levels were main features characterizing patients.

Low-grade inflammation may play a role in the etiology of the metabolic syndrome in patients with coronary heart disease: the HIFMECH study

Risk of coronary heart disease has been related to insulin resistance, but the mechanism for this is incompletely understood. Variables attributed to insulin resistance are associated with low-grade inflammation. A case-control study was performed of 469 male myocardial infarction (MI) survivors aged < 60 years and 575 control subjects recruited from centers in northern and southern Europe. Principal factor analysis was used to explore correlations between insulin resistance and inflammatory variables. Three factors resulted: (a) "Metabolic Syndrome" (insulin/proinsulin/ triglyceride/body mass index [BMI]); (b) "Inflammation" (fibrinogen/C-reactive protein [CRP]/interleukin-6 [IL-6]); and (c) "Blood Pressure" (systolic and diastolic blood pressure). The "Metabolic Syndrome" factor was related to the "Inflammation" factor (largely independently of obesity), the "Blood Pressure" factor, smoking, and south location (all P < or = .0002). There were significant relationships between all 3 factors and case status (P < or = .0002). Markers of low-grade inflammation are strongly related to metabolic syndrome variables independently of obesity. This raises the possibility that links between insulin resistance and cardiovascular disease could, in part, represent common consequences of low-grade inflammation.

Expression of fatty-acid-handling proteins in human adipose tissue in relation to obesity and insulin resistance

AIMS/HYPOTHESIS

Protein-mediated trans-membrane and intracellular fatty acid trafficking are becoming increasingly recognised as biochemically and physiologically important concepts. Obesity and insulin resistance are polygenic disorders, heavily influenced by environmental and life-style factors, and are virtually always associated with disturbed fatty acid metabolism in adipose and other tissues. The aim of this study was to investigate mRNA expression levels of fatty-acid-handling proteins in adipose tissue in relation to markers of genetic and acquired obesity and insulin resistance.

METHODS

We quantified mRNA expression of subcutaneous adipose tissue fatty-acid-handling proteins (ALBP, KLBP, FATP1, FATP4, CD36, ACS1) in 17 monozygotic twin-pairs with a range of intra-pair differences (Delta) in BMI and detailed measures of obesity and insulin resistance, allowing influences of genetic and non-genetic factors to be distinguished.

RESULTS

In acquired obesity FATP4 expression was up-regulated independently of genetic background (DeltaFATP4 versus DeltaBMI; r=0.50, p=0.04; DeltaFATP4 versus Deltabody fat; r=0.59, p=0.01). Similarly, CD36 and FATP1 expression correlated with acquired differences in HDL cholesterol and non-esterified fatty acid concentrations respectively. Moreover, FATP4 and CD36 expression levels correlated with measures of obesity and insulin resistance that are influenced by both genetic and non-genetic factors (FATP4 versus BMI: r=0.53, p=0.0001; FATP4 versus body fat: r=0.51, p=0.002; FATP4 versus homeostasis model assessment [HOMA]: r=0.49, p=0.001; CD36 versus BMI: r=0.50, p=0.02; CD36 versus body fat: r=0.63, p=0.001; CD36 versus HOMA: r=0.34, p=0.06).

CONCLUSIONS/INTERPRETATION

These findings indicate that expression of specific adipose tissue fatty-acid-handling proteins is related to obesity and insulin resistance, and that, in particular, FATP4 plays a role in acquired obesity. Our results suggest that facilitated fatty acid trafficking is a physiologically and pathologically relevant phenomenon in man.

Sex hormone–binding globulin—A surrogate marker for the prothrombotic effects of combined oral contraceptives

OBJECTIVE

The purpose of this study was to investigate the plausibility of serum sex hormone-binding globulin (SHBG) concentration as a risk marker for venous thromboembolism (VTE) during use of combined oral contraceptives (COC). Study design This was a prospective, randomized cross-over study. Thirty-five women were treated with COCs containing the same amount of ethinyl estradiol and either levonorgestrel (LNG/EE) or desogestrel (DG/EE). Serum SHBG and markers of hemostasis were determined before and after 2 months on each treatment.

RESULTS

SHBG increased significantly with both preparations. Treatment with DG/EE caused more pronounced prothrombotic changes in hemostatic parameters than LNG/EE. With both treatment regimens, there was a significant correlation between changes in resistance to activated protein C (APCr) and changes in plasma SHBG.

CONCLUSION

The correlation between SHBG and the well-established risk factor APCr might indicate the usefulness of SHBG as a risk marker for VTE during COC treatment.

Genetic and structural evaluation of fatty acid transport protein-4 in relation to markers of the insulin resistance syndrome

Disturbances in fatty acid metabolism are involved in the etiology of insulin resistance and the related dyslipidemia, hypertension, and procoagulant state. The fatty acid transport proteins (FATPs) are implicated in facilitated cellular uptake of nonesterified fatty acids (NEFAs), thus potentially regulating NEFA concentrations and metabolism. The aim of this study was to investigate polymorphic loci in the FATP4 gene with respect to associations with fasting and postprandial lipid and lipoprotein variables and markers of insulin resistance in 608 healthy, middle-aged Swedish men and to evaluate possible mechanisms behind any associations observed. Heterozygotes for a Gly209Ser polymorphism (Ser allele frequency 0.05) had significantly lower body mass index and, correcting for body mass index, significantly lower triglyceride concentrations, systolic blood pressure, insulin concentrations, and homeostasis model assessment index compared with common homozygotes. A three-dimensional model of the FATP4 protein based on structural and functional similarity with adenylate-forming enzymes revealed that the variable residue 209 is exposed in a region potentially involved in protein-protein interactions. Furthermore, the model indicated functional regions with respect to NEFA transport and acyl-coenzyme A synthase activity and membrane association. These findings propose FATP4 as a candidate gene for the insulin resistance syndrome and provide a structural basis for understanding FATP function in NEFA transport and metabolism.

Peroxisome proliferator activated receptor delta genotype in relation to cardiovascular risk factors and risk of coronary heart disease in hypercholesterolaemic men

OBJECTIVES

Peroxisome proliferator activated receptor delta (PPARD) is a transcription factor implicated in the regulation of genes involved in cholesterol metabolism. We recently discovered a common polymorphism in the 5'-untranslated region (5'-UTR) of the human PPARD, +294T/C, that is associated with an increased plasma low-density lipoprotein cholesterol (LDL-C) concentration in healthy subjects. Whether the +294C allele is associated with LDL-C elevation independently of the background lipoprotein phenotype and whether it confers increased risk of coronary heart disease (CHD) is unknown. Against this background, we investigated the relationships between the PPARD polymorphism and plasma lipoprotein concentrations and the risk for contracting CHD in the West of Scotland Coronary Prevention Study (WOSCOPS).

DESIGN

A nested case-control study of participants in a randomized double-blind placebo-controlled trial of pravastatin in mildly-to-moderately hypercholesterolaemic men.

SUBJECTS

A total of 580 cases of incident CHD and 1160 individuals who remained free of CHD (controls).

MAIN OUTCOME MEASURES

Plasma lipoprotein concentrations and risk of CHD according to PPARD genotype.

RESULTS

Individuals carrying the rare PPARD +294C allele had a significantly lower high-density lipoprotein cholesterol (HDL-C) concentration than subjects homozygous for the common T-allele. Homozygous carriers of the C-allele also showed a tendency towards higher risk of CHD compared with homozygous carriers of the T-allele. In addition, a gene-gene interaction involving the PPARD polymorphism and the PPAR alpha L162V polymorphism may influence the plasma LDL-C concentration.

CONCLUSIONS

PPARD plays a role in cholesterol metabolism in man.

Genetic approach to the role of cysteine proteases in the expansion of abdominal aortic aneurysms

Background

The elastinolytic cysteine proteases, including cathepsins S and K, are overexpressed at sites of arterial elastin damage. Cystatin C, an inhibitor of these enzymes, is expressed in arterial smooth muscle cells; an imbalance in cystatin C has been implicated in the aortic wall degeneration observed in abdominal aortic aneurysms (AAAs). The aim of the study was to investigate the impact of a polymorphism in the signal peptide of the cystatin C gene on the growth of small AAAs.

Methods

Some 424 patients with a small AAA (4·0–5·5 cm) were monitored for AAA growth by ultrasonography and provided a DNA sample for analysis of the + 148 G &gt; A polymorphism in the cystatin C signal peptide and the—82 G &gt; C polymorphism in the gene promoter. The median length of follow-up was 2·8 years and AAA growth rates were calculated by linear regression analysis.

Results

For patients of + 148 GG (n = 263), GA (n = 147) and AA (n = 20) genotypes, the mean(s.d.) AAA growth rates were 0·37(0·29), 0·37(0·23) and 0·30(0·26) cm, and initial diameters were 4·58(0·35), 4·58(0·35) and 4·62(0·36) cm, respectively. Patients of + 148 AA genotype had a slower aneurysm growth rate (unadjusted P = 0·058; after adjustment for age, sex, initial AAA diameter and smoking, P = 0·027). There also was a trend for the rare homozygotes of the—82 C allele to have slower AAA growth (adjusted P = 0·055). Smoking history had a stronger association with aneurysm growth (P = 0·003).

Conclusion

There was a weak association between variation in the cystatin C gene and AAA growth. Medical strategies to limit AAA growth might include the inhibition of cysteine proteases.

The plasminogen activator inhibitor-1 -675 4G/5G genotype influences the risk of myocardial infarction associated with elevated plasma proinsulin and insulin concentrations in men from Europe: the HIFMECH study

Although the potential role of plasminogen activator inhibitor-1 (PAI-1) in the development of coronary artery disease is strongly supported by its biological characteristics, results of clinical studies remain controversial.

OBJECTIVES

To investigate whether plasma PAI-1 concentrations and the -675 4G/5G polymorphism located in the PAI-1 gene could constitute risk markers for myocardial infarction (MI).

PATIENTS AND METHODS

We used a European case-control study, the HIFMECH study, comparing 598 men with MI and 653 age-matched controls.

RESULTS

Insulin resistance explained a major part of the variation in PAI-1 (24%) whereas inflammation had only a minor contribution (0.01%). For both cases and controls plasma PAI-1 concentrations were significantly higher in the North than the South, and in both regions were higher in individuals with MI compared with control subjects [overall odds ratio (OR) for a 1 SD increase=1.54, 95% confidence interval (CI) 1.34, 1.77]. This difference was observed in all the centers studied. Overall, the difference between cases and control subjects remained significant after controlling for inflammation variables (OR=1.30, 95% CI 1.08, 1.57), but lost significance after controlling for insulin resistance variables (OR=1.17, 95% CI 0.98, 1.40). The 4G allele was associated with significantly higher PAI-1 levels in cases but not controls and, taken independently, did not modify the risk of MI (P=0.9). However, a significant interaction was observed with both insulin or proinsulin and the risk of MI (P=0.05 and 0.02, respectively), but not with triglycerides or body mass index (BMI). The insulin or proinsulin effect on risk was observed only in the carriers of the 4G/4G genotype. This interaction appeared not to be mediated by plasma PAI-1 antigen concentrations (P=0.01 and 0.02 after adjustment for PAI-1 plasma levels). The interaction with proinsulin but not insulin remained statistically significant after further adjustment for other factors associated with insulin resistance (triglycerides and BMI) and C-reactive protein (P=0.01).

CONCLUSION

This study suggests that PAI-1 has a role in risk of MI in the presence of underlying insulin resistance. A significant interaction between insulin or proinsulin and the -675 4G/5G polymorphism was observed in risk for MI. The mechanisms for these interactions remain to be determined.

Prognostic value of plasma C-reactive protein and fibrinogen determinations in patients with acute myocardial infarction treated with thrombolysis

OBJECTIVES

To investigate the prognostic value of plasma C-reactive protein (CRP) and fibrinogen determinations in patients with acute myocardial infarction treated with thrombolysis.

DESIGN

Longitudinal study of morbidity and mortality.

SETTING

Coronary care unit at Danderyd Hospital, Stockholm, Sweden.

SUBJECTS

A total of 222 patients aged 75 years or below, treated with thrombolysis because of typical symptoms of myocardial infarction and electrocardiogram showing ST-segment elevation or bundle branch block were included in the study. The patients were followed for 24-60 months (mean 40 +/- 16 months).

MAIN OUTCOME MEASURES

Cardiovascular death or new myocardial infarction.

RESULTS

Concentrations of CRP were significantly higher at 48 h than at 3 months, whilst the levels of fibrinogen were similar. CRP and fibrinogen concentrations measured during the acute phase of myocardial infarction were associated with cardiovascular death or a new myocardial infarction during follow-up in univariate analysis. CRP levels measured 3 months after the acute event were not associated with subsequent events whereas fibrinogen concentrations showed a borderline prognostic significance (P = 0.05). When CRP and fibrinogen were entered into multivariate analysis together with the previously established prognostic factors in the patient group (age, diabetes mellitus and left ventricular function), these markers of inflammation did not add further prognostic information.

CONCLUSION

C-reactive protein and fibrinogen do not carry the same independent prognostic information after acute myocardial infarction treated with thrombolysis as in studies previously reported for patients with unstable angina or non-Q-wave myocardial infarction.

TNF-alpha: a link between hypertriglyceridaemia and inflammation in SLE patients with cardiovascular disease

Patients with systemic lupus erythematosus (SLE) are at high risk of cardiovascular disease (CVD). Tumour necrosis factor-alpha (TNF-alpha) has been implicated in the pathophysiological processes of both SLE and CVD. This study focuses on the role of TNF-alpha and its soluble receptors in SLE-related CVD. In summary, 26 women (52 +/- 8.2 years) with SLE and a history of CVD (SLE cases) we compared with 26 age-matched women with SLE and no clinical manifestations of CVD (SLE controls) and 26 age-matched population-based control women (population controls). Plasma concentrations of circulating TNF-alpha, TNF-alpha receptor 1 (sTNFR1) and TNF-a receptor 2 (sTNFR2) were determined by ELISA. TNF-alpha, sTNFR1 and sTNFR2 were raised in SLE cases as compared to SLE controls (P = 0.009; P = 0.001; P = 0.001, respectively), and SLE controls had higher levels than population controls (P = 0.001; P = 0.02; P = 0.001, respectively). Exclusively in the SLE case group there was a striking positive correlation between TNF-alpha and plasma triglycerides (r = 0.57, P < 0.002), VLDL triglycerides (r = 0.54, P = 0.004) and VLDL cholesterol (r = 0.58, P = 0.002). Furthermore, TNF-alpha correlated with the waist-hip ratio but not with estimated insulin resistance. TNF-alpha may thus be a major factor in SLE-related CVD acting both by contributing to hypertriglyceridaemia and by promoting atherosclerosis-related inflammation. sTNFR1 and sTNFR2 are strongly associated with CVD in SLE but their exact roles in disease development remain to be elucidated.