Insulin and aging - a disappointing relationship.

Experimental studies in animal models of aging such as nematodes, fruit flies or mice have observed that decreased levels of insulin or insulin signaling promotes longevity. In humans, hyperinsulinemia and concomitant insulin resistance are associated with an elevated risk of age-related diseases suggestive of a shortened healthspan. Age-related disorders include neurodegenerative diseases, hypertension, cardiovascular disease, and type 2 diabetes. High ambient insulin concentrations promote increased lipogenesis and fat storage, heightened protein synthesis and accumulation of non-functional polypeptides due to limited turnover capacity. Moreover, there is impaired autophagy activity, and less endothelial NO synthase activity. These changes are associated with mitochondrial dysfunction and oxidative stress. The cellular stress induced by anabolic activity of insulin initiates an adaptive response aiming at maintaining homeostasis, characterized by activation of the transcription factor Nrf2, of AMP activated kinase, and an unfolded protein response. This protective response is more potent in the long-lived human species than in short-lived models of aging research resulting in a stronger pro-aging impact of insulin in nematodes and fruit flies. In humans, resistance to insulin-induced cell stress decreases with age, because of an increase of insulin and insulin resistance levels but less Nrf2 activation. These detrimental changes might be contained by adopting a lifestyle that promotes low insulin/insulin resistance levels and enhances an adaptive response to cellular stress, as observed with dietary restriction or exercise.

The Epidemiological Boehringer Ingelheim Employee Study (Part 3): Association of Elevated Fasting Insulin Levels but Not HOMA-IR With Increased Intima Media Thickness and Arteriosclerosis in Middle-Aged Persons.

Background: Recently published genetic studies have indicated a causal link between elevated insulin levels and cardiovascular disease (CVD) risk. We, therefore, hypothesized that increased fasting insulin levels are also associated with precursors of CVD such as endothelial lesions. Methods: Middle-aged (≥40 years, n = 1,639) employees were followed up for the occurrence of increased intima media thickness (IMT ≥ 1 mm) or plaques in abdominal or cervical arteries (arteriosclerosis). Multivariable logistic regression analyses determined the incidence of increased IMT or arteriosclerosis. Adjusted relative risk (ARR) for increased IMT and arteriosclerosis was calculated by using Mantel-Haenszel analysis. Results: Increased IMT was diagnosed in 238 participants (15 %) and 328 (20 %) developed arteriosclerosis after 5 years of follow-up. Logistic regression analysis identified fasting insulin, BMI and smoking as risk factors for both cardiovascular endpoints (all p < 0.05), whereas age and diastolic blood pressure were risk factors for increased IMT only, and male sex was associated with incident arteriosclerosis only (all p < 0.01). Additional adjustment for BMI change during follow-up did not modify these associations (including fasting insulin), but adjustment for fasting insulin change during follow-up removed BMI as risk factor for both cardiovascular endpoints. Fasting insulin change during follow-up but not BMI change associated with increased IMT and arteriosclerosis (both p < 0.001). ARR analysis indicated that high fasting insulin and BMI added to age and sex as risk factors. Homeostatic model assessment of insulin resistance (HOMA-IR) did not associate with either cardiovascular endpoint in any model and smoking did not increase the risk conferred by high fasting insulin levels. Conclusions: Higher fasting insulin levels and increases in fasting insulin over time are associated with atherogenic progression and supersede BMI as well as HOMA-IR as risk factors.

Health Effects of Coffee: Mechanism Unraveled?

The association of habitual coffee consumption with a lower risk of diseases, like type 2 diabetes mellitus, chronic liver disease, certain cancer types, or with reduced all-cause mortality, has been confirmed in prospective cohort studies in many regions of the world. The molecular mechanism is still unresolved. The radical-scavenging and anti-inflammatory activity of coffee constituents is too weak to account for such effects. We argue here that coffee as a plant food has similar beneficial properties to many vegetables and fruits. Recent studies have identified a health promoting mechanism common to coffee, vegetables and fruits, i.e., the activation of an adaptive cellular response characterized by the upregulation of proteins involved in cell protection, notably antioxidant, detoxifying and repair enzymes. Key to this response is the activation of the Nrf2 (Nuclear factor erythroid 2-related factor-2) system by phenolic phytochemicals, which induces the expression of cell defense genes. Coffee plays a dominant role in that regard because it is the major dietary source of phenolic acids and polyphenols in the developed world. A possible supportive action may be the modulation of the gut microbiota by non-digested prebiotic constituents of coffee, but the available data are still scarce. We conclude that coffee employs similar pathways of promoting health as assumed for other vegetables and fruits. Coffee beans may be viewed as healthy vegetable food and a main supplier of dietary phenolic phytochemicals.

Chaperones may cause the focus of diabetes autoimmunity on distinct (pro)insulin peptides.

It is still an enigma why T cell autoreactivity in type 1 diabetes targets few beta cell antigens only. Among these, one primary autoantigen is pro(insulin). Autoimmune T cells preferentially recognise three epitopes on the proinsulin molecule, of which the peptide region B:11-23 is the dominant one. Interestingly, the three regions superimpose with binding sites of the chaperone hsp70, the region B:11-23 being the strongest binding one. Absence of an intact core region B:15-17 prevents autoimmune diabetes in NOD as well as binding of hsp70. A role of hsp70 in selecting autoimmune epitopes is supported by the ability of this and other chaperones to deliver bound peptides to MHC class I and II molecules for efficient antigen presentation. Binding of hsp70 to receptors on antigen presenting cells such as TLR4 results in costimulatory signals for T cell activation. Strongest effects are seen for the mixture of hsp70 with the peptide B:11-23. Thus, hsp70 may assist in proinsulin epitope selection and efficient presentation to autoreactive T cells. The concept of chaperone guided immune reactivity may also apply to other autoimmune diseases.

The Autoantigenic Proinsulin B-Chain Peptide B11-23 Synergises with the 70 kDa Heat Shock Protein DnaK in Macrophage Stimulation.

BACKGROUND: Heat shock proteins (Hsp) act as intracellular chaperones and in addition are used as adjuvant in vaccines of peptides complexed with recombinant Hsp. By interacting with autologous peptides, Hsp may promote the induction of autoimmune reactivity. OBJECTIVE: Here, we analysed whether the effect of Hsp on macrophages is modulated by insulin peptides known to interact with Hsp. RESULTS: Combinations of the 70 kDa Hsp DnaK with peptide B11-23 from the core region of the proinsulin B-chain induced the release of the inflammatory mediators interleukin-6, tumor necrosis factor α, and interleukin-1ß from cells of human and murine macrophage lines. In parallel, there was high-affinity binding of B11-23 to DnaK. DnaK mixed with peptides from other regions of the insulin molecule did not stimulate cytokine secretion. DnaK alone induced little cytokine production, and peptides alone induced none. CONCLUSION: The macrophage-stimulating potential of Hsp70 family proteins when combined with the proinsulin B-chain peptide B11-23 may contribute to the immunodominance of this peptide in the development of beta cell-directed autoimmunity in type 1 diabetes.

Environmental/lifestyle factors in the pathogenesis and prevention of type 2 diabetes.

BACKGROUND: Environmental and lifestyle changes, in addition to the ageing of populations, are generally believed to account for the rapid global increase in type 2 diabetes prevalence and incidence in recent decades. DISCUSSION: In this review, we present a comprehensive overview of factors contributing to diabetes risk, including aspects of diet quality and quantity, little physical activity, increased monitor viewing time or sitting in general, exposure to noise or fine dust, short or disturbed sleep, smoking, stress and depression, and a low socioeconomic status. In general, these factors promote an increase in body mass index. Since loss of ß-cell function is the ultimate cause of developing overt type 2 diabetes, environmental and lifestyle changes must have resulted in a higher risk of ß-cell damage in those at genetic risk. Multiple mechanistic pathways may come into play. CONCLUSIONS: Strategies of diabetes prevention should aim at promoting a 'diabetes-protective lifestyle' whilst simultaneously enhancing the resistance of the human organism to pro-diabetic environmental and lifestyle factors. More research on diabetes-protective mechanisms seems warranted.

Inverse Relationship Between Organ-Specific Autoantibodies and Systemic Immune Mediators in Type 1 Diabetes and Type 2 Diabetes: Action LADA 11.

OBJECTIVE: We related organ-specific autoantibodies, including diabetes-associated autoantibodies (DAAs) and non-DAAs to systemic cytokines/chemokines in type 1 and type 2 diabetes. RESEARCH DESIGN AND METHODS: From the European Action LADA (latent autoimmune diabetes in adults) cohort, patients with adult-onset type 1 diabetes (n = 80, of whom 50 had LADA and 30 had classic type 1 diabetes) and type 2 diabetes (n = 626) were analyzed for DAAs (GAD antibody [GADA], IA-2 antigen, islet cell antibody, and zinc transporter T8), non-DAAs (transglutaminase, thyroid peroxide autoantibodies, parietal cell antibodies), and 10 immune mediator concentrations (measured by LUMINEX). RESULTS: Type 1 diabetes patients (whether having classic type 1 diabetes or LADA), apart from their clinical phenotype, could not be distinguished by either autoantibodies (both DAAs and non-DAAs) or immune mediators. In type 1 diabetes, most immune mediators (9 of 10) were negatively correlated with DAA titers. Type 2 diabetes patients, who by definition were without DAAs, had fewer non-DAAs (P < 0.0005), but had higher levels of proinflammatory immune mediators, especially compared with patients with type 1 diabetes who had high GADA titers (interleukin [IL]-6 [P < 0.001], soluble E-selectin [P < 0.01], and IL-1 receptor antagonist [P = 0.052], for trend). CONCLUSIONS: Patients with type 1 diabetes had more DAAs and non-DAAs than did those with type 2 diabetes, whereas the frequency and nature of these autoantibodies was broadly similar in classic type 1 diabetes and LADA. Systemic immune mediator levels, in the main, were negatively correlated with DAA titers, and, for some, were higher in patients with type 2 diabetes, especially when compared with patients who had high GADA titers. Differences in the clinical classification of diabetes are associated with graded differences in adaptive and innate immune reactivity.

Toll-like receptor 4 deficiency accelerates the development of insulin-deficient diabetes in non-obese diabetic mice.

BACKGROUND/OBJECTIVE: Toll-like receptors (TLR) mediate the recognition of microbial constituents and stress-induced endogenous ligands by the immune system. They may also be involved in the maintenance or break down of tolerance against autologous antigens. The aim of our investigation was to study the consequence of TLR4 deficiency on the development of insulin-deficient diabetes in the NOD mouse. METHODS: The TLR4 defect of the C57BL/10ScN mouse was backcrossed onto the NOD background and the effect of TLR4 deficiency on diabetes development was analysed by in vivo and in vitro studies. RESULTS: Compared to animals with wildtype TLR4 expression (TLR4(+/+)), female NOD mice carrying a homozygous TLR4 defect (TLR4(-/-)), showed significant acceleration of diabetes development, with a younger age at diabetes onset (TLR4 (+/+) 177±22 d, TLR(-/-): 118±21 d; p<0.01). Pancreata of 120 d old TLR4(-/-) NOD mice revealed increased proportions of islets with advanced stages of immune cell infiltration compared to TLR4(+/+) mice (p<0.05). TLR4 deficiency did not affect the susceptibility of islet cells to the beta cell damaging mediators nitric oxide or the inflammatory cytokines tumor necrosis factor alpha, interleukin-1 beta and interferon gamma. The lack of TLR4 further had no effect on the frequency of regulatory T-cells but reduced their capacity to inhibit T-cell proliferation. CONCLUSIONS: Our findings demonstrate that TLR4 deficiency results in an acceleration of diabetes development and immune cell infiltration of islets in NOD mice. We conclude that TLR4 is involved in the progression of the insulitis process thereby controlling the development of insulin-deficient diabetes in NOD mice.

Proinflammatory cytokines, adiponectin, and increased risk of primary cardiovascular events in diabetic patients with or without renal dysfunction: results from the ESTHER study.

OBJECTIVE: Inflammatory processes contribute to both diabetes and cardiovascular risk. We wanted to investigate whether circulating concentrations of proinflammatory immune mediators and adiponectin in diabetic patients are associated with incident cardiovascular events. RESEARCH DESIGN AND METHODS: In 1,038 participants with diabetes of the population-based ESTHER study, of whom 326 showed signs of renal dysfunction, Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs for the association of increasing concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), IL-18, macrophage migration inhibitory factor (MIF), adiponectin, and leptin with cardiovascular events (myocardial infarction, stroke, or fatal cardiovascular event) during a follow-up period of 8 years. RESULTS: During follow-up, 161 subjects with diabetes experienced a primary cardiovascular event. Proinflammatory markers were not associated with a higher risk for primary cardiovascular events in the total study population after adjustment for multiple confounders. However, IL-6 and MIF were associated with cardiovascular events in subjects with renal dysfunction (HR for the comparison of top vs. bottom tertile 1.98 [95% CI 1.12-3.52], P [trend] = 0.10 for IL-6; 1.48 [0.87-2.51], P [trend] = 0.04 for MIF). Adiponectin levels were associated with cardiovascular events in the total population (1.48 [1.01-2.21], P [trend] = 0.03), and the association was even more pronounced in the subgroup with renal dysfunction (1.97 [1.08-3.57], P [trend] = 0.02). CONCLUSIONS: In particular, the absence of an association between CRP and a U-shaped association of adiponectin levels with incident cardiovascular events show that associations between circulating immune mediators and cardiovascular risk differ between diabetic patients and subjects of the general population.

Serum adipokines as biomarkers of beta-cell function in patients with type 1 diabetes: positive association with leptin and resistin and negative association with adiponectin.

BACKGROUND: We investigated the adipokines adiponectin, leptin and resistin as serum biomarkers of beta-cell function in patients with type 1 diabetes. METHODS: One hundred and eighteen patients with type 1 diabetes (20.3 ± 7.5 years) diagnosed <5 years underwent standardized mixed meal test (MMTT) for 2 h. Systemic concentrations of C-peptide, adiponectin, leptin and resistin obtained during MMTT were measured and compared between patient groups by multiple regression analysis. RESULTS: Patients were divided by their adipokine levels in subgroups above or below the median level ('high versus low'). High adiponectin levels (>10.6 µg/mL) were associated with lower C-peptide compared to the low adiponectin subgroup (p < 0.03). Increased leptin or resistin concentrations associated positively with beta-cell function even after adjustment for metabolic confounders (p < 0.04). The described associations between adipokines and C-peptide concentrations persisted in Spearman correlation tests (p < 0.05). Serum adipokines fell during MMTT (p < 0.05). CONCLUSIONS: Serum adipokine levels differentially correlate with beta-cell function in type 1 diabetes independent of BMI or metabolic control. Serum adipokines should be investigated as biomarkers of beta-cell function in prospective studies and intervention trials in type 1 diabetes.

Interleukin-6 in the prediction of primary cardiovascular events in diabetes patients: results from the ESTHER study.

OBJECTIVES: Circulating interleukin-6 (IL-6) is increased in diabetes patients who are in general also at greater cardiovascular risk. Thus, we investigated whether IL-6 is associated with incident primary cardiovascular events and improves risk prediction in diabetes patients. METHODS: Serum IL-6 levels were measured at baseline in 1072 diabetic participants of the ESTHER study. During 5 years of follow-up, 84 experienced a primary cardiovascular event (myocardial infarction, stroke, cardiovascular death). Hazard ratios (HR) and 95% confidence intervals (95% CI), measures of model discrimination and calibration were calculated. RESULTS: High IL-6 levels were associated with increased event risk (adjusted HR 1.90 [95% CI 1.06-3.40] for top versus bottom tertile; p = 0.011). The addition of IL-6 to models containing Framingham score variables did not substantially improve prediction. CONCLUSIONS: Although serum IL-6 was significantly associated with cardiovascular risk, it did not substantially improve risk prediction above traditional risk factors in a diabetic cohort.

Sex differences in the prediction of type 2 diabetes by inflammatory markers: results from the MONICA/KORA Augsburg case-cohort study, 1984-2002.

OBJECTIVE: Although sex differences have been reported for associations between obesity and inflammation, the question of whether there is an effect modification by sex in the association between inflammation and type 2 diabetes has not been investigated in detail. Therefore, the aim of this study was to compare associations of markers of inflammation with type 2 diabetes risk between men and women. RESEARCH DESIGN AND METHODS: Following a case-cohort design, cases of incident type 2 diabetes were identified from 7,936 subjects aged 35-74 years at baseline who participated in the population-based Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA)/Cooperative Research in the Region of Augsburg (KORA) studies conducted between 1984 and 2002. Concentrations of C-reactive protein (CRP) and interleukin (IL)-6 were measured in 527 cases of incident type 2 diabetes (305 men and 222 women) and 1,698 noncases (889 men and 809 women). RESULTS: After adjustment for age and survey and lifestyle factors including smoking, alcohol intake, and physical activity, elevated concentrations of CRP showed a considerably stronger association with risk of type 2 diabetes in women (hazard ratio comparing tertile extremes 7.60 [95% CI 4.43-13.04]) than in men (1.84 [1.27-2.67]). The P value for the sex interaction was <0.001. Further adjustment for metabolic risk factors considerably attenuated these associations, and they became nonsignificant in men but remained significant in women. IL-6 was also more strongly associated with type 2 diabetes in women, but there was no significant sex interaction. CONCLUSIONS: Our data suggest that inflammatory processes may be of particular importance in the pathogenesis of type 2 diabetes in women.

Increased concentrations of C-reactive protein and IL-6 but not IL-18 are independently associated with incident coronary events in middle-aged men and women: results from the MONICA/KORA Augsburg case-cohort study, 1984-2002.

OBJECTIVE: We performed a prospective case-cohort study in initially healthy, middle-aged men and women from the MONICA/KORA Augsburg studies conducted between 1984 and 2002 to assess the role of IL-18 in comparison with IL-6 and CRP in the prediction of incident coronary heart disease (CHD). METHODS AND RESULTS: Concentrations of IL-18 were measured in 382 case subjects with incident CHD and 1980 noncases. Mean follow-up was 11 years. Baseline concentrations of IL-18 were slightly higher in cases than in noncases (172.4 [1.0] versus 161.3 [1.0] pg/mL, respectively; P=0.114), but were clearly elevated for C-reactive protein (CRP) and IL-6 in cases compared with noncases. In multivariable analyses, accounting for classical cardiovascular risk factors and inflammatory markers, no statistically significant association was seen between increased concentrations of IL-18 and incident CHD both in men (hazard ratio [HR] and 95% confidence intervals [CIs] comparing extreme tertiles, 1.20; 95% CI, 0.85 to 1.69), and in women (HR, 1.25; 95% CI, 0.67 to 2.34). However, in this population increased concentrations of CRP and IL-6 were found to be independent predictors of future CHD events, even after multivariable adjustment. CONCLUSIONS: Elevated concentrations of CRP and IL-6, but not IL-18, were independently associated with risk of CHD in subjects from an area with moderate absolute risk.

Systemic immune mediators and lifestyle changes in the prevention of type 2 diabetes: results from the Finnish Diabetes Prevention Study.

The Finnish DPS (Diabetes Prevention Study) demonstrated that lifestyle intervention, aimed at increasing physical activity, improving diet, and decreasing body weight, reduced the incidence of type 2 diabetes in individuals with overweight and impaired glucose tolerance by 58%. Here, we studied which immunological markers at baseline predicted subsequent type 2 diabetes and whether there are immunologically defined subsets of subjects who are more or less responsive to the protective effects of lifestyle intervention. We randomly assigned 522 participants to a control group (n = 257) or a lifestyle intervention group (n = 265). Immunological parameters at baseline included high-sensitivity C-reactive protein (CRP), serum amyloid A, interleukin-6, regulated on activation normal T-cell expressed and secreted (RANTES), macrophage migration inhibitory factor (MIF), and soluble intercellular adhesion molecule. In the control group, CRP was the best immunological predictor for progression to overt type 2 diabetes. In the intervention group, progression to type 2 diabetes was significantly higher in subjects with the highest RANTES concentrations and was lower in subjects with the highest MIF levels. Ratios of RANTES to MIF in the upper tertile were highly predictive of incident type 2 diabetes in the intervention group (P = 0.006), whereas the association was less pronounced in the control group (P = 0.088). Thus, systemic concentrations of immune mediators appear to be associated with the progression to type 2 diabetes and the prevention of type 2 diabetes by lifestyle changes.

Hypoadiponectinemia and proinflammatory state: two sides of the same coin?: results from the Cooperative Health Research in the Region of Augsburg Survey 4 (KORA S4).

OBJECTIVE: Previous studies have yielded conflicting results on the association of adiponectin levels and inflammation. Low systemic concentrations of adiponectin, as well as elevated levels of immune mediators, represent risk factors for the development of type 2 diabetes and coronary artery disease. The major aim of this cross-sectional study was to investigate the interdependence of hypoadiponectinemia and low-grade systemic inflammation. RESEARCH DESIGN AND METHODS: The study sample consisted of 606 participants aged 55-74 years (244 with normal glucose tolerance, 242 with impaired glucose tolerance, and 120 with newly diagnosed type 2 diabetes) of the population-based KORA S4 (Cooperative Health Research in the Region of Augsburg Survey 4; 1999-2001). Systemic concentrations of adiponectin and a wide range of anthropometric, metabolic, and inflammatory variables were available for analyses. The association of adiponectin with 15 immunological markers, including leukocyte count, acute-phase proteins, cytokines, cytokine receptors, and chemokines, was assessed using univariable and multivariable models. RESULTS: No evidence for a significant correlation between adiponectin and all immunological parameters except eotaxin could be found after multivariable adjustments, whereas multiple strong correlations with obesity and metabolic factors were present. CONCLUSIONS: From these data, we conclude that hypoadiponectinemia and a proinflammatory state are largely independent from each other.

Association of cardiovascular risk factors with markers of endothelial dysfunction in middle-aged men and women. Results from the MONICA/KORA Augsburg Study.

Endothelial dysfunction plays an important role in the pathogenesis of cardiovascular diseases and diabetes mellitus. However, the causes underlying endothelial dysfunction are not fully understood. Therefore, the aim of the present study was to investigate associations of cardiovascular risk factors with soluble adhesion molecules (sE-Selectin, sICAM-1), soluble thrombomodulin (sTM) and von Willebrand factor (vWF) as markers of endothelial dysfunction. The study population consisted of a subcohort of 2,168 men and women aged 35 to 74 years randomly drawn from three cross-sectional population-based MONICA/KORA Augsburg surveys conducted between 1984 and 1995. In multivariable linear regression analysis, current smoking, high (versus moderate) alcohol consumption, ratio of total cholesterol/HDL-cholesterol (TC/HDL-C) and C-reactive protein (CRP) were significantly associated with elevated levels of sE-selectin and sICAM-1. Increased levels of sE-selectin were also found in subjects with actual hypertension, high body mass index and prevalent diabetes mellitus. In addition, low physical activity and no (versus moderate) alcohol consumption were significantly associated with elevated concentrations of sICAM-1. Levels of sTM were higher in subjects with actual hypertension, no or high amounts of alcohol intake and a high ratio of TC/HDL-C, but were lower in subjects with a history of myocardial infarction. VWF was significantly associated with CRP only. In conclusion, sE-selectin and sICAM-1 are more strongly associated with traditional cardiovascular risk factors than sTM and vWF.

Association of systemic concentrations of macrophage migration inhibitory factor with impaired glucose tolerance and type 2 diabetes: results from the Cooperative Health Research in the Region of Augsburg, Survey 4 (KORA S4).

OBJECTIVE: Macrophage migration inhibitory factor (MIF) is a central cytokine in innate immunity. MIF expression can be regulated by glucose and insulin, but data on the association with type 2 diabetes are sparse. The aim of this study was to test whether MIF is associated with impaired glucose tolerance (IGT) and type 2 diabetes and whether these associations are independent of metabolic and immunological risk factors and to compare the associations of MIF and IGT/type 2 diabetes with those of C-reactive protein (CRP) and interleukin-6 (IL-6) with IGT/type 2 diabetes. RESEARCH DESIGN AND METHODS: The Cooperative Health Research in the Region of Augsburg/Kooperative Gesundheitsforschung im Raum Augsburg, Survey 4 (KORA S4) is a population-based survey performed in Southern Germany (1999-2001). Of 1,653 participants aged 55-74 years, 236 patients with type 2 diabetes, 242 subjects with IGT, and 244 normoglycemic control subjects matched for age and sex were included in this cross-sectional study. Serum concentrations of MIF were measured by enzyme-linked immunosorbent assay. RESULTS: Serum MIF concentrations are highly increased in individuals with IGT and type 2 diabetes. The associations of MIF with IGT and type 2 diabetes were independent of classical risk factors and of CRP and IL-6 and were much stronger before and after multivariate adjustment than the associations of CRP and IL-6 with IGT and type 2 diabetes. CONCLUSIONS: Our data suggest that elevations of systemic MIF concentrations precede the onset of type 2 diabetes. This finding may be relevant because MIF has been reported to contribute to the development of type 2 diabetes-related diseases such as atherosclerosis and cancer.

Sex differences in the relation of body composition to markers of inflammation.

OBJECTIVE: It has been suggested that low-grade systemic inflammation is associated with obesity and that this association might be modified by sex. METHODS AND RESULTS: We performed a cross-sectional analysis among 641 men and 597 women aged 55-74 years who participated in the population-based KORA Survey 2000, conducted in the area of Augsburg, Germany. Measures of both total (fat mass, body mass index) and abdominal adiposity (waist circumference (WC), waist to hip ratio (WHR)) were highly correlated with markers of systemic inflammation (C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen (FIB), interleukin-6 (IL-6)) in men and in women. Significant associations persisted when the effect of lifestyle factors was taken into account. In multivariable linear regression analysis, a considerably higher percentage of variability in inflammatory markers was explained by body composition in women compared to men. Furthermore, the relevance of single body composition variables varied by sex. In women, fat mass in % explained the highest percentage of the variability of circulating acute-phase proteins (18.2% for CRP, 7.2% for SAA, 6.1% for FIB, all p-values < 0.001), whereas in men, WHR explained the highest percentage of the variability (6.2% for CRP, 2.3% for SAA, 1.8% for FIB, all p-values < 0.001). For IL-6, WC explained the highest percentage of the variability in women (3.7%, p < 0.001) and in men (1.8%, p < 0.001). CONCLUSION: Adiposity is strongly associated with low-grade systemic inflammation in men and in women but the association is considerably stronger in women, especially for CRP. Thus, weight reduction as a means to prevent a state of subclinical inflammation might be particularly effective in women.

Heat shock protein 60: identification of specific epitopes for binding to primary macrophages.

In the present study, we characterized regions of human heat shock protein (HSP) 60 responsible for binding to primary macrophages. Studies using 20-mer peptides of the HSP60 sequence to compete with HSP60-binding to macrophages from C57BL/6J mice showed that regions aa241-260, aa391-410 and aa461-480 are involved in surface-binding. HSP60 mutants, lacking the N-terminal 137, 243 or 359 amino acids, inhibited HSP60-binding to primary macrophages to different degrees, demonstrating that all three regions are required for optimal binding. Analysis of different pro- and eukaryotic HSP60 species indicated that phylogenetically separate HSP60 species use different binding sites on primary macrophages.

Elevated levels of interleukin-18 predict the development of type 2 diabetes: results from the MONICA/KORA Augsburg Study, 1984-2002.

We investigated prospectively the association between serum levels of interleukin (IL)-18 and the risk of type 2 diabetes in a case-cohort study conducted in middle-aged men and women who represented 7,936 participants of the three MONItoring of trends and determinants in CArdiovascular disease (MONICA)/Cooperative Research in the Region of Augsburg (KORA) surveys. Levels of IL-18 were measured in stored samples of 527 case subjects with incident type 2 diabetes and 1,698 noncase subjects. Elevated levels of IL-18 were associated with a significantly increased risk of type 2 diabetes after adjustment for age, sex, survey, BMI, systolic blood pressure, ratio of total cholesterol to HDL cholesterol, physical activity, alcohol intake, smoking status, and parental history of diabetes. Hazard ratios and 95% confidence intervals comparing quartile extremes were 1.73 (1.25-2.40). Further adjustment for C-reactive protein and IL-6 had no impact on the observed associations. However, the risk of developing type 2 diabetes was highest among subjects with elevated levels of both IL-18 and CRP or IL-18 and IL-6, respectively. In conclusion, elevated levels of IL-18 are associated with a considerably increased risk of type 2 diabetes. This association is independent of a generalized proinflammatory state, but subjects with elevated levels of several inflammatory markers seem to be particularly prone to develop type 2 diabetes.