Insulin resistance is increasingly recognized as a chronic, low-level, inflammatory state. Hyperinsulinemia and insulin action were initially proposed as the common preceding factors of hypertension, low high-density lipoprotein cholesterol, hypertriglyceridemia, abdominal obesity, and altered glucose tolerance, linking all these abnormalities to the development of coronary heart disease. The similarities of insulin resistance with another inflammatory state, atherosclerosis, have been described only in the last few decades. Atherosclerosis and insulin resistance share similar pathophysiological mechanisms, mainly due to the actions of the two major proinflammatory cytokines, TNF-alpha and IL-6. Genetic predisposition to increased transcription rates of these cytokines is associated with metabolic derangement and simultaneously with coronary heart disease. Dysregulation of the inflammatory axis predicts the development of insulin resistance and type 2 diabetes mellitus. The knowledge of how interactions between metabolic and inflammatory pathways occur will be useful in future therapeutic strategies. The effective administration of antiinflammatory agents in the treatment of insulin resistance and atherosclerosis is only the beginning of a promising approach in the management of these syndromes.

Insulin resistance and chronic cardiovascular inflammatory syndrome.

The key concept of proteomics (looking at many proteins at once) opens new avenues in the search for clinically useful biomarkers of disease, treatment response and ageing. As the number of proteins that can be detected in plasma or serum (the primary clinical diagnostic samples) increases towards 1000, a paradoxical decline has occurred in the number of new protein markers approved for diagnostic use in clinical laboratories. This review explores the limitations of current proteomics protein discovery platforms, and proposes an alternative approach, applicable to a range of biological/physiological problems, in which quantitative mass spectrometric methods developed for analytical chemistry are employed to measure limited sets of candidate markers in large sets of clinical samples. A set of 177 candidate biomarker proteins with reported associations to cardiovascular disease and stroke are presented as a starting point for such a ‘directed proteomics’ approach.

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Candidate-based proteomics in the search for biomarkers of cardiovascular disease

Circulating markers of inflammation and atherosclerosis.

Critical review of acylation-stimulating protein physiology in humans and rodents

Postprandial recruitment of neutrophils may contribute to endothelial dysfunction

Aims Serum C3 is a powerful indicator of the risk of myocardial infarction, which correlates with body mass index, serum lipids and blood pressure. This study was performed to ascertain whether such correlations may be explained by an association of C3 with fasting insulin, and to assess comparatively the relationships of C3 and traditional risk factors to previous myocardial infarction. Methods and Results The fasting levels of C3, insulin, and the main risk factors were evaluated in 1090 unselected men aged 55-64 years, including 129 cases of previous ischaemic events (51 myocardial infarctions). In multivariate analysis C3 was associated with insulin (r=0.27, P<0.0001), cholesterol (r=0.18, P<0.0001), body mass index (r=0.13, P<0.0001), glucose (r=0.12, P=0.0001), systolic blood pressure (r=0.10, P<0.001), triglycerides (r=0.09, P<0.01) and HDL-cholesterol (r= -0.06, P<0.05). These variables explained 31% of the total C3 variance. Alcohol consumption and physical activity correlated inversely with C3, while no correlation was found with smoking and family history of myocardial infarction. C3 was associated with previous myocardial infarction and stroke, but not with angina pectoris and peripheral arterial disease. In logistic regression the variables associated with previous myocardial infarction were C3 (P=0.011), family history of myocardial infarction (P=0.018), ex-smoker status (P=0.020), age (P=0.025), glucose (P=0.028) and HDL-cholesterol (P=0.051, inverse relationship). Conclusions The association of C3 with myocardial infarction persists retrospectively, and is more significant than any other association of traditional risk factors with previous myocardial infarction. Of the many variables associated with C3, fasting insulin is its main covariate, which suggests that C3 is a marker of a pro-atherogenic metabolic imbalance partly coinciding with insulin resistance.

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P. Pacilli

Papers

Relationship of serum C3 to fasting insulin, risk factors and previous ischaemic events in middle-aged men.

Transthoracic electrical bioimpedance: a non-invasive technique for the evaluation of the haemodynamic alterations in patients with liver cirrhosis.