Inflammation-sensitive plasma proteins are associated with future weight gain

Familial clustering for features of the metabolic syndrome: the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study

OBJECTIVE

Metabolic syndrome-related traits (obesity, glucose intolerance/insulin resistance, dyslipidemia, and hypertension) have been shown to be genetically correlated. It is less clear, however, if the genetic correlation extends to novel risk factors associated with inflammation, impaired fibrinolytic activity, and hyperuricemia. We present a bivariate genetic analysis of MetS-related traits including both traditional and novel risk factors.

RESEARCH DESIGN AND METHODS

Genetic correlations were estimated using a variance components procedure in 1,940 nondiabetic white individuals from 445 families in the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study. Twelve MetS-related traits, including BMI, waist circumference, blood pressure, white blood cell count, fasting serum triglycerides, HDL cholesterol, insulin, glucose, plasminogen activator inhibitor-1 antigen, uric acid, and C-reactive protein, were measured and adjusted for covariates, including lifestyle variables.

RESULTS

Significant genetic correlations were detected among BMI, waist circumference, HDL cholesterol, triglycerides, insulin, and plasminogen activator inhibitor-1 antigen and between uric acid and all of the above variables except insulin. C-reactive protein and white blood cell count were genetically correlated with each other, and both showed significant genetic correlations with waist circumference and insulin. Fasting glucose was not significantly genetically correlated with any of the other traits.

CONCLUSIONS

These results suggest that pleiotropic effects of genes or shared family environment contribute to the familial clustering of MetS-related traits.

Retinal vessel diameters and obesity: a population-based study in older persons

OBJECTIVE

Obesity is linked with large vessel atherosclerosis and diabetes. Its association with microvascular changes is less clear. We investigated the associations among retinal vessel diameters, vessel wall signs, and BMI in an older population.

RESEARCH METHODS AND PROCEDURES

Retinal photographs were taken on 3654 persons aged 49+ years at baseline of the Blue Mountains Eye Study in Australia. Arteriolar and venular diameters were measured from digitized retinal photographs of the right eyes. BMI was calculated as weight (kilograms)/height (meters2). Incident obesity was defined in persons with BMI < or = 30 at baseline but > 30 after 5 years. A significant weight gain was defined as an increase in BMI of 2+ SDs (4 or more units) over the 5-year period.

RESULTS

At baseline, mean BMI was 26.1 (+/-4.6) in this population. At 5-year examinations, 177 (10.0% of 1773 at risk) developed incident obesity, and 136 (6.4% of 2143 at risk) had significant weight gain. After adjusting for age, sex, smoking, triglyceride levels, and mean arterial blood pressure, persons with wider retinal venular diameters had a higher risk of incident obesity (odds ratio, 1.8; 95% confidence interval, 1.0 to 3.1, comparing the highest with lowest venular diameter quintiles) and significant weight gain (odds ratio, 1.7; 95% confidence interval, 0.9 to 3.2). These associations were attenuated with further adjustment for baseline BMI. Arteriolar diameter was unrelated with baseline or change in BMI.

DISCUSSION

Wider retinal venular diameter is associated with risk of obesity, independent of hypertension, diabetes, lipids, and cigarette smoking. These data may support a role for impaired microvascular function in the course of weight gain.

The epidemiology of low-grade chronic systemic inflammation and type 2 diabetes

The fattening of the human species and the accompanying emergence of the metabolic syndrome and of type 2 diabetes as remarkably frequent clinical entities are among the major epidemiologic events of our time. Control of the diabetes epidemic requires a greater understanding of the pathophysiologic processes underlying these phenomena. Many epidemiologic studies have now shown associations between inflammation markers and diabetes, with the most consistent being for leukocytes and the strongest being for C-reactive protein. Consistent protective associations have also been reported for adiponectin, an adipocyte secretory protein with antiinflammatory actions. Although great variability is seen between reported associations, as a whole these studies suggest a role for inflammation linked to obesity. The variability reported is in part due to differences in model adjustment, in how diabetes was ascertained, and in the different means used to operationalize the concept of low-grade chronic systemic inflammation. It is also due, in part, to sample characterization, as findings are heterogeneous across some subgroups, such as those defined by smoking. Consistent with their association with type 2 diabetes, inflammation markers have also be shown to predict conditions present in the prediabetes state such as weight gain, hypertension, gestational diabetes, and decline in insulin sensitivity.

Endocrine and signalling role of adipose tissue: new perspectives on fat

White adipose tissue (WAT) is now recognized as a major endocrine and secretory organ, releasing a wide range of protein factors and signals termed adipokines - in addition to fatty acids and other lipid moieties. A paradigm shift came with the discovery of leptin, a pleiotropic hormone which is a critical signal to the hypothalamus in the control of appetite and energy balance. A number of adipokines, including adiponectin, tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-8, IL-10, monocyte chemoattractant protein-1, macrophage migration inhibitory factor, nerve growth factor, vascular endothelial growth factor, plasminogen activator inhibitor-1 and haptoglobin, are linked to inflammation and the inflammatory response. Obesity is characterized by a state of mild inflammation, and the expression and release of inflammation-related adipokines generally rises as adipose tissue expands; a notable exception is adiponectin, with its anti-inflammatory action, the levels of which fall. WAT may be the main site of inflammation in obesity, increased circulating levels of inflammatory markers reflecting spillover from an 'inflamed' tissue, leading to the obesity-associated pathologies of type 2 diabetes and the metabolic syndrome. From the wide range of adipokines now identified, it is evident that WAT is highly integrated into overall physiological regulation, involving extensive crosstalk with other organs and multiple metabolic systems. Whether major changes in adipokine production in obesity, particularly of those factors linked to inflammation, are unique to this condition, or are a feature of all situations in which there are substantial increases in adipose mass (such as pregnancy, and pre-hibernatory and pre-migratory fattening) requires consideration.

Does oxidative stress change ceruloplasmin from a protective to a vasculopathic factor?

Although ceruloplasmin (CP), a copper containing metalloenzyme, possesses antioxidant properties (e.g. ferroxidase activity), elevated circulating CP is associated with cardiovascular disease (CVD). This ambivalence is possibly due to the capacity of CP, via its coppers, to promote vasculopathic effects that include lipid oxidation, negation of nitric oxide bioactivity and endothelial cell apoptosis. In turn, these effects that are mediated by increased formation of reactive oxygen species (ROS), such as superoxide and hydrogen peroxide. There is also evidence that risk factors for CVD (in particular, diabetes mellitus and hyperhomocysteinaemia) may augment the vasculopathic impact of CP. In turn, it appears that ROS disrupt copper binding to CP, thereby impairing its normal protective function while liberating copper which in turn may promote oxidative pathology. The objective of this review, therefore, is to consider the epidemiology and pathophysiology of CP in relation to CVD, with particular emphasis on the relationship between CP and oxidative stress.

Weight gain in relation to plasma levels of complement factor 3: results from a population-based cohort study

AIMS/HYPOTHESIS

Mice that are deficient for complement factor 3 (C3) have shown resistance to weight gain, despite increased food intake. Cross-sectional studies of humans have reported correlations between C3 and obesity. This longitudinal study explored whether C3 predicts a large weight gain in middle-aged men.

METHODS

Plasma concentrations of C3 and complement factor 4 (C4) were measured in 2,706 non-diabetic healthy men aged between 38 and 50 years, who were re-examined after a mean period of 6.1 years.

RESULTS

After adjustments for initial weight, age, height and follow-up time, the odds of incurring large weight gain (75th percentile, > or =3.8 kg) were 1.00 (reference), 0.96 (95% CI:0.7-1.2), 1.1 (CI:0.9-1.5) and 1.4 (CI:1.1-1.8), respectively, among men with C3 levels in the first, second, third and fourth quartiles (p for trend=0.01) respectively. This relationship remained significant after further adjustments for lifestyle factors (physical inactivity, alcohol, smoking), metabolic factors (glucose or homeostasis model assessment values, cholesterol, triglycerides), inflammatory markers (fibrinogen, haptoglobin, ceruloplasmin, orosomucoid, alpha1-antitrypsin) and for C4. C4 was associated with weight gain after adjustments for initial weight, height, follow-up time and lifestyle factors, but not after adjustments for C3.

CONCLUSIONS/INTERPRETATION

C3 is a risk factor for incurring large weight gain in middle-aged men.

Signalling role of adipose tissue: adipokines and inflammation in obesity

White adipose tissue (WAT) is a major endocrine and secretory organ, which releases a wide range of protein signals and factors termed adipokines. A number of adipokines, including leptin, adiponectin, tumour necrosis factor α, IL-1β (interleukin 1β), IL-6, monocyte chemotactic protein-1, macrophage migration inhibitory factor, nerve growth factor, vascular endothelial growth factor, plasminogen activator inhibitor 1 and haptoglobin, are linked to inflammation and the inflammatory response. Obesity is characterized by a state of chronic mild inflammation, with raised circulating levels of inflammatory markers and the expression and release of inflammation-related adipokines generally rises as adipose tissue expands (adiponectin, which has anti-inflammatory action is an exception). The elevated production of inflammation-related adipokines is increasingly considered to be important in the development of diseases linked to obesity, particularly Type II diabetes and the metabolic syndrome. WAT is involved in extensive cross-talk with other organs and multiple metabolic systems through the various adipokines.

The pro-inflammatory cytokine IL-18 is expressed in human adipose tissue and strongly upregulated by TNFalpha in human adipocytes

White adipocytes have been examined as a potential source of interleukin-18 (IL-18), the circulating levels of which are increased in obesity. IL-18 gene expression was evident in human subcutaneous and visceral adipose tissue, and expression occurred in mature adipocytes and the stromal-vascular fraction. Expression of the IL-18 receptor complex (IL-18Ralpha and IL-18Rbeta) and the IL-18 binding protein (IL-18BP) genes was also observed, mirroring that of IL-18. IL-18 mRNA level increased rapidly (within 2h) and dramatically (>900-fold) in response to TNFalpha in human adipocytes differentiated in culture. IL-18 protein was detected in lysates of cultured adipocytes, though not in the medium. There was a small increase in IL-18 in lysates of adipocytes treated with TNFalpha, but the protein was again undetectable in the medium. IL-18 may be part of the inflammatory cascade within adipose tissue; however, human adipocytes do not appear to secrete significant amounts of IL-18.

Effect of sucrose on inflammatory markers in overweight humans

BACKGROUND

Observational studies have found that dietary glycemic load is positively associated with C-reactive protein (CRP) concentrations in healthy humans, which suggests that the type of carbohydrate ingested influences inflammatory activity.

OBJECTIVE

We investigated the effect of a diet with a high content of sucrose or artificial sweeteners on the inflammatory markers CRP, haptoglobin, and transferrin in overweight subjects.

DESIGN

Overweight men and women consumed daily food and drink supplements containing either sucrose [n = 21; body mass index (BMI, in kg/m2): 28.0] or artificial sweeteners (n = 20; BMI: 27.6), predominantly from soft drinks (70%; average approximately 1.3 L/d) for 10 wk.

RESULTS

During the intervention, sucrose intake increased by 151% in the sucrose group and decreased by 42% in the sweetener group, resulting in a 1.6-kg weight gain in the sucrose group and a 1.2-kg weight loss in the sweetener group over 10 wk (P < 0.001). Concentrations of haptoglobin, transferrin, and CRP increased by 13%, 5%, and 6%, respectively, in the sucrose group and decreased by 16%, 2%, and 26%, respectively, in the sweetener group (between-group differences: P = 0.006, P = 0.01, and P = 0.1, respectively). Adjustment for changes in body weight and energy intake did not substantially influence this outcome.

CONCLUSIONS

The study shows that in the present group of overweight subjects a high consumption of sugar-sweetened foods and drinks increased haptoglobin and transferrin but had, at best, only a limited influence on CRP.

Cardiovascular stress responsivity, body mass and abdominal adiposity

OBJECTIVE

To assess the relationship between adiposity and cardiovascular stress reactivity and recovery in middle-aged men and women, and investigate the influence of impaired poststress cardiovascular recovery on changes in body mass index (BMI) and waist-hip ratio over 3 y.

PARTICIPANTS

In total, 225 healthy men and women aged 47-59 y were recruited from the British civil service.

METHODS

Laboratory mental stress testing was carried out, with blood pressure (BP), cardiac output and total peripheral resistance being measured at baseline, during moderately challenging tasks, and during recovery 40-45 min poststress. Weight, height, waist and hip circumference were assessed at the time of mental stress testing and 3 y later.

RESULTS

Behavioural tasks elicited increases in BP sustained by a combination of cardiac activation and raised peripheral resistance. BMI and waist/hip ratio were associated cross-sectionally with impaired poststress recovery of systolic pressure, diastolic pressure and cardiac index independently of age, gender, socioeconomic status, smoking, alcohol consumption and baseline cardiovascular activity. Increases in waist-hip ratio over 3 y were predicted both by impaired poststress recovery of systolic pressure and cardiac index in men, independently of baseline adiposity and other covariates. No associations between subjective stress and BMI or waist-hip ratio were observed.

CONCLUSIONS

Disturbances of cardiovascular responsivity to psychological stress, manifest through impaired poststress recovery, were associated cross-sectionally with BMI, and longitudinally with central adiposity in men. Stress-related cardiovascular dysregulation may contribute to obesity risk.

Pathophysiology of metabolic syndrome X and its links to the perinatal period

It is proposed that metabolic syndrome X is initiated in the perinatal period as a low-grade systemic inflammatory condition. Increased consumption of energy-dense diets by pregnant women and lactating mothers suppresses the activities of Delta-6 and Delta-5 desaturases not only in maternal tissues but also in fetal liver and the placenta, resulting in decreased plasma and tissue concentrations of long-chain polyunsaturated fatty acids omega-6 arachidonic acid (AA), omega-3 eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). EPA, DHA, and AA have negative feedback control on tumor necrosis factor-alpha and IL-6 synthesis. Hence, EPA, DHA, and AA deficiencies induced by an energy-dense diet increase generation of tumor necrosis factor-alpha and interleukin-6, markers of inflammation that in turn decrease production of endothelial nitric oxide and adiponectin to induce insulin resistance in maternal and fetal tissues. Increased concentrations of tumor necrosis factor-alpha and interleukin-6 enhance expression and activity of 11beta-hydroxysteroid dehydrogenase type 1 enzyme, which produces abdominal obesity, insulin resistance, hyperlipidemia, hyperphagia, and hyperleptinemia, characteristic features of metabolic syndrome X. Continued consumption of an energy-dense diet in childhood aggravates these molecular events. This implies that supplementation of long-chain polyunsaturated fatty acids (especially AA, EPA, and DHA in appropriate ratios) from the perinatal period through adulthood could prevent, arrest, or postpone development of metabolic syndrome X.

A burning question: does an adipokine-induced activation of the immune system mediate the effect of overnutrition on type 2 diabetes?

There is growing support for the hypothesis that obesity is an inflammatory condition leading to chronic activation of the innate immune system, which ultimately causes progressive impairment of glucose tolerance. Experimental studies in animals and evidence from prospective and longitudinal studies in humans are consistent with an etiologic role of subclinical inflammation in the pathogenesis of type 2 diabetes, primarily as a mediator of obesity-induced insulin resistance. However, the exact chain of molecular events linking overnutrition, activation of the innate immune system, and impairment of insulin signaling in peripheral tissues remains incompletely understood. Notwithstanding this limitation, treating the underlying subclinical inflammation may constitute a novel approach to prevention and/or treatment of type 2 diabetes.

Complement C3 is a risk factor for the development of diabetes: a population-based cohort study

Cross-sectional studies have reported strong correlations between plasma levels of complement C3, insulin, and glucose. This prospective study explored whether elevated levels of C3, C4, and other inflammation-sensitive plasma proteins (ISPs; fibrinogen, orosomucoid, alpha1-antitrypsin, haptoglobin, and ceruloplasmin) are associated with the development of diabetes. Plasma proteins were measured in 2,815 nondiabetic healthy men, age 38-50 years, who were reexamined after a mean follow-up of 6.1 years. Diabetes development (n = 123) was studied in relation to baseline levels of plasma proteins. After adjusting for age, screening year, and glucose at baseline, the odds ratio (95% CI) for developing diabetes was 1.00, 2.4 (1.1-5.3), 2.9 (1.4-6.0), and 5.6 (2.8-10.9), respectively, for men with C3 in the 1st, 2nd, 3rd, and 4th quartiles (trend: P < 0.00001). Fibrinogen, haptoglobin, C4, and the number of elevated ISPs were also related to future diabetes in this model. Only C3 was significantly associated with diabetes development after further adjustments for potential confounders, including BMI, insulin, and other inflammatory markers. We concluded that the risk of developing diabetes is related to levels of complement C3.

Risk Factors for Stroke in Subjects With Normal Blood Pressure

Background and Purpose— Although stroke is strongly associated with hypertension, some individuals with normal blood pressure (BP) experience a stroke. This prospective study explored risk factors for stroke in subjects with normal BP.

Methods— A total of 11 228 men and 17 174 women, 45 to 73 years old, were examined in a population-based cohort study. Normal BP was defined as BP <140/90 mm Hg and no treatment for hypertension. The incidence of stroke was followed over a mean period of 6 years.

Results— In the cohort, 10 938 (38%) had normal BP. Of them, 56 patients experienced a first-ever stroke (12% of all stroke). Compared with subjects without stroke during follow-up, these stroke subjects were older, had lower education, were often smokers and alcohol nondrinkers, and had a history of coronary heart disease (CHD), gastric ulcer, or renal calculus. Subjects with stroke had a higher body mass index (BMI) and a high-normal BP (130 to 139/85 to 89 mm Hg) more often. In a backward stepwise Cox-regression analysis, age (per 1 year; relative risk [RR], 1.12), current smoking (RR, 3.21), BMI (per SD; RR, 1.39), high-normal diastolic BP (RR, 2.35), history of CHD (RR, 4.92), and gastric ulcer (RR, 2.21) remained significantly associated with incidence of stroke.

Conclusion— In subjects with normal BP, there are a number of potentially modifiable risk factors associated with an increased incidence of stroke.

Metabolic syndrome X: an inflammatory condition?

Obesity, atherosclerosis, insulin resistance and hyperinsulinemia, hyperlipidemia, essential hypertension, type 2 diabetes mellitus, and coronary heart disease (CHD) are the components of metabolic syndrome X and are associated with elevated plasma levels of C-reactive protein, interleukin-6, and tumor necrosis factor-alpha, which are markers of inflammation. This suggests that metabolic syndrome X is a low-grade, systemic, inflammatory condition. Hence, instituting anti-inflammatory measures might be beneficial in preventing or halting the progress of metabolic syndrome X in high-risk populations.

Metabolic syndrome X: an inflammatory condition?

Obesity, atherosclerosis, insulin resistance and hyperinsulinemia, hyperlipidemia, essential hypertension, type 2 diabetes mellitus, and coronary heart disease (CHD) are the components of metabolic syndrome X and are associated with elevated plasma levels of C-reactive protein, interleukin-6, and tumor necrosis factor-alpha, which are markers of inflammation. This suggests that metabolic syndrome X is a low-grade, systemic, inflammatory condition. Hence, instituting anti-inflammatory measures might be beneficial in preventing or halting the progress of metabolic syndrome X in high-risk populations.

Adipokines: inflammation and the pleiotropic role of white adipose tissue

White adipose tissue is now recognised to be a multifunctional organ; in addition to the central role of lipid storage, it has a major endocrine function secreting several hormones, notably leptin and adiponectin, and a diverse range of other protein factors. These various protein signals have been given the collective name 'adipocytokines' or 'adipokines'. However, since most are neither 'cytokines' nor 'cytokine-like', it is recommended that the term 'adipokine' be universally adopted to describe a protein that is secreted from (and synthesised by) adipocytes. It is suggested that the term is restricted to proteins secreted from adipocytes, excluding signals released only by the other cell types (such as macrophages) in adipose tissue. The adipokinome (which together with lipid moieties released, such as fatty acids and prostaglandins, constitute the secretome of fat cells) includes proteins involved in lipid metabolism, insulin sensitivity, the alternative complement system, vascular haemostasis, blood pressure regulation and angiogenesis, as well as the regulation of energy balance. In addition, there is a growing list of adipokines involved in inflammation (TNFalpha, IL-1beta, IL-6, IL-8, IL-10, transforming growth factor-beta, nerve growth factor) and the acute-phase response (plasminogen activator inhibitor-1, haptoglobin, serum amyloid A). Production of these proteins by adipose tissue is increased in obesity, and raised circulating levels of several acute-phase proteins and inflammatory cytokines has led to the view that the obese are characterised by a state of chronic low-grade inflammation, and that this links causally to insulin resistance and the metabolic syndrome. It is, however, unclear as to the extent to which adipose tissue contributes quantitatively to the elevated circulating levels of these factors in obesity and whether there is a generalised or local state of inflammation. The parsimonious view is that the increased production of inflammatory cytokines and acute-phase proteins by adipose tissue in obesity relates primarily to localised events within the expanding fat depots. It is suggested that these events reflect hypoxia in parts of the growing adipose tissue mass in advance of angiogenesis, and involve the key controller of the cellular response to hypoxia, the transcription factor hypoxia inducible factor-1.

NGF gene expression and secretion in white adipose tissue: regulation in 3T3-L1 adipocytes by hormones and inflammatory cytokines

The sympathetic nervous system plays a central role in lipolysis and the production of leptin in white adipose tissue (WAT). In this study, we have examined whether nerve growth factor (NGF), a target-derived neurotropin that is a key signal in the development and survival of sympathetic neurons, is expressed and secreted by white adipocytes. NGF mRNA was detected by RT-PCR in the major WAT depots of mice (epididymal, perirenal, omental, mesenteric, subcutaneous) and in human fat (subcutaneous, omental). In mouse WAT, NGF expression was observed in mature adipocytes and in stromal vascular cells. NGF expression was also evident in 3T3-L1 cells before and after differentiation into adipocytes. NGF protein, measured by ELISA, was secreted from 3T3-L1 cells, release being higher before differentiation. Addition of the sympathetic agonists norepinephrine, isoprenaline, or BRL-37344 (beta(3)-agonist) led to falls in NGF gene expression and secretion by 3T3-L1 adipocytes, as did IL-6 and the PPARgamma agonist rosiglitazone. A substantial decrease in NGF expression and secretion occurred with dexamethasone. In contrast, LPS increased NGF mRNA levels and NGF secretion. A major increase in NGF mRNA level (9-fold) and NGF secretion (<or=40-fold) in 3T3-L1 adipocytes occurred with TNF-alpha. RT-PCR showed that the genes encoding the p75 and trkA NGF receptors were expressed in mouse WAT. These results demonstrate that white adipocytes secrete NGF (an adipokine), NGF synthesis being influenced by several factors with TNF-alpha having a major stimulatory effect. We suggest that NGF is a target-derived neurotropin and an inflammatory response protein in white adipocytes.

Incidence of Obesity-Associated Cardiovascular Disease Is Related to Inflammation-Sensitive Plasma Proteins

Background— Although obesity is associated with increased inflammation, it is unclear whether this accounts for the increased cardiovascular risk in obesity. This population-based study explored whether inflammation-sensitive plasma proteins (ISPs) modify the cardiovascular risk in overweight or obese men.

Methods and Results— The ISPs (fibrinogen, orosomucoid, α1-antitrypsin, haptoglobin, ceruloplasmin) were measured in 6075 healthy men, aged 28 to 61 years. The incidences of cardiovascular events (myocardial infarction, stroke, cardiovascular deaths), cardiac events (fatal or nonfatal myocardial infarction), and stroke were followed-up over 18±4 years. High ISPs were associated with an increased cardiovascular risk in all categories of body mass index (BMI). The age-adjusted relative risks for cardiovascular events in obese men (BMI >30) were 2.1 (95% CI, 1.4 to 3.4), 2.4 (CI, 1.5 to 3.7), 3.7 (CI, 2.3 to 6.0), and 4.5 (CI, 3.0 to 6.6), respectively, for those with 0, 1, 2, and ≥3 ISPs in the top quartile (trend P =0.002) (reference: BMI <25 and no elevated ISP). This trend persisted after adjustments for several potential confounders ( P =0.02). Incidence of cardiac events showed similar relations with the number of elevated ISPs in obese men.

Conclusion— The cardiovascular risk varies widely between obese or overweight men with high and low ISPs. Relationships with ISPs contribute to, but cannot fully explain, the increased cardiovascular risk in obese men.

Risk of Myocardial Infarction and Stroke in Smokers Is Related to Plasma Levels of Inflammation-Sensitive Proteins

BACKGROUND

The extent to which differences in cardiovascular risk between smokers with similar daily tobacco consumption may be related to plasma levels of inflammation-sensitive proteins (ISP) and whether these proteins are associated with levels of carboxyhemoglobin (COHb%) have not been clarified.

METHODS AND RESULTS

In a population-based cohort of 1489 never smokers, 1685 former smokers, and 2901 current smokers, aged 28 to 61 years, plasma levels of orosomucoid (alpha(1)-acid glycoprotein), alpha(1)-antitrypsin, haptoglobin, fibrinogen, and ceruloplasmin were measured. COHb% levels were available for 2098 of them. Incidence of myocardial infarction, stroke, and death were monitored over 18.7+/-4.7 years. The proportion with high ISP levels (ie, > or =2 ISP in the top quartile) increased progressively with daily tobacco consumption (P<0.01) and COHb% (P<0.01). In all smoking categories, the incidence of stroke, cardiac events, and death was related to ISP. In heavy smokers, high ISP levels were associated with adjusted relative risks of 1.57 (1.05 to 2.35) and 1.50 (1.11 to 2.03) for cardiac events and death, respectively. Corresponding figures for moderate and light smokers were 1.59 (1.13 to 2.24) and 1.14 (0.87 to 1.49), respectively, and 1.32 (0.95 to 1.85) and 1.48 (1.10 to 1.98), respectively.

CONCLUSIONS

ISP levels are related to COHb% in smokers. High levels are associated with an increased cardiovascular risk.

A prospective study of aspirin use and the risk of pancreatic cancer in women

BACKGROUND

In vitro experiments and limited animal studies suggest that aspirin and nonsteroidal anti-inflammatory drugs may inhibit pancreatic carcinogenesis. Because few studies have examined the association between aspirin use and pancreatic cancer in humans and the results have been inconsistent, we examined the relationship between aspirin use and the development of pancreatic cancer in the Nurses' Health Study.

METHODS

Among 88 378 women without cancer at baseline, we documented 161 cases of pancreatic cancer during 18 years of follow-up. Aspirin use was first assessed at baseline in 1980 and updated biennially thereafter. All statistical tests were two-sided.

RESULTS

Participants were classified according to history of aspirin use. In a multivariable analysis, the risk of pancreatic cancer was not associated with current regular aspirin use (defined as two or more standard tablets per week; relative risk [RR] = 1.20, 95% confidence interval [CI] = 0.87 to 1.65), compared with use of fewer than two tablets per week. Increasing duration of regular aspirin use, compared with non-use, was associated with a statistically significant increase in risk: Women who reported more than 20 years of regular aspirin use had an increased risk of pancreatic cancer (RR = 1.58, 95% CI = 1.03 to 2.43; P(trend) =.01). Among women who reported aspirin use on at least two of three consecutive biennial questionnaires compared with consistent non-users of aspirin, the risk increased with dose (one to three tablets per week: RR = 1.11, 95% CI = 0.70 to 1.76; four to six tablets per week: RR = 1.29, 95% CI = 0.70 to 2.40; seven to 13 tablets per week: RR = 1.41, 95% CI = 0.76 to 2.61; and > or = 14 tablets per week: RR = 1.86, 95% CI = 1.03 to 3.35) (P(trend) =.02).

CONCLUSION

Extended periods of regular aspirin use appear to be associated with a statistically significantly increased risk of pancreatic cancer among women.

Inflammation-sensitive plasma proteins and incidence of myocardial infarction in men with low cardiovascular risk

OBJECTIVE

Myocardial infarction (MI) is sometimes experienced by individuals without any traditional risk factor. This prospective study explored whether incidence of MI in nonsmoking, nondiabetic men with normal blood pressure and serum lipids is related to inflammation-sensitive plasma proteins (ISPs).

METHODS AND RESULTS

Five ISPs (alpha1-antitrypsin, haptoglobin, ceruloplasmin, fibrinogen, orosomucoid) were analyzed in 6075 men, 47+/-3.6 years old. A low-risk group (no traditional risk factor, n=1108) and a high-risk group (> or =2 major risk factors, n=1011) were defined. Incidence of MI (n=227) was monitored over 18.1+/-4.3 years of follow-up. In the low-risk group, the age-adjusted relative risks (RRs) were 1.00 (reference), 1.9 (95% CI, 0.8 to 4.2), 1.8 (95% CI, 0.6 to 5.4), and 2.9 (95% CI, 1.05 to 8.1), respectively, for men with 0, 1, 2 and > or =3 ISPs in the top quartile (trend: P=0.03). In this group, the increased risk was observed only after > or =10 years of follow-up. In the high-risk group, the age-adjusted RRs were 1.00, 1.4 (95% CI, 0.9 to 2.2), 1.9 (95% CI, 1.2 to 3.1), and 2.0 (95% CI, 1.3 to 3.1), respectively, for men with 0, 1, 2, and > or =3 ISPs in the top quartile (trend: P=0.0004).

CONCLUSIONS

Incidence of MI in nonsmoking, nondiabetic men with normal blood pressure and lipids was related to ISPs. The causes for this relationship remain to be explored.