Stephan Martin

Effects of coffee consumption on subclinical inflammation and other risk factors for type 2 diabetes: a clinical trial

BACKGROUND Coffee consumption is associated with a decreased risk of type 2 diabetes. Suggested mechanisms underlying the association have included attenuation of subclinical inflammation and a reduction in oxidative stress. OBJECTIVE The aim was to investigate the effects of daily coffee consumption on biomarkers of coffee intake, subclinical inflammation, oxidative stress, glucose, and lipid metabolism. DESIGN Habitual coffee drinkers (n = 47) refrained for 1 mo from coffee drinking; in the second month they consumed 4 cups of filtered coffee/d and in the third month 8 cups of filtered coffee/d (150 mL/cup). Blood samples were analyzed by gas chromatography-mass spectrometry, bead-based multiplex technology, enzyme-linked immunosorbent assay, or immunonephelometry. RESULTS Coffee consumption led to an increase in coffee-derived compounds, mainly serum caffeine, chlorogenic acid, and caffeic acid metabolites. Significant changes were also observed for serum concentrations of interleukin-18, 8-isoprostane, and adiponectin (medians: -8%, -16%, and 6%, respectively; consumption of 8 compared with 0 cups coffee/d). Serum concentrations of total cholesterol, HDL cholesterol, and apolipoprotein A-I increased significantly by 12%, 7%, and 4%, respectively, whereas the ratios of LDL to HDL cholesterol and of apolipoprotein B to apolipoprotein A-I decreased significantly by 8% and 9%, respectively (8 compared with 0 cups coffee/d). No changes were seen for markers of glucose metabolism in an oral-glucose-tolerance test. CONCLUSIONS Coffee consumption appears to have beneficial effects on subclinical inflammation and HDL cholesterol, whereas no changes in glucose metabolism were found in our study. Furthermore, many coffee-derived methylxanthines and caffeic acid metabolites appear to be useful as biomarkers of coffee intake.

Transcription and translation of inducible nitric oxide synthase in the pancreas of prediabetic BB rats

The inducible NO synthase (iNOS) was found to be expressed in pancreatic lesions of adult diabetes‐prone BB rats. Pancreatic iNOS mRNA was detected by reverse transcriptase PCR in pancreatic RNA of adult diabetes‐prone BB rats but not in normal Wistar rats, young diabetes‐prone BB rats without insulitis or in diabetes‐resistant BB rats. Immunohistochemistry of pancreatic sections using an iNOS‐specific antiserum labeled the pancreas of adult diabetes‐prone BB rats but not Wistar rats. Parallel staining for EDI‐positive macrophages showed restriction of iNOS expression to areas of islet infiltration by macrophages. In conclusion, the data provide direct evidence for enhanced expression of inducible NO synthase in tissue lesions during the development of autoimmune diabetes.

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.

Objectives—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.

Pentoxifylline, a phosphodiesterase inhibitor, induces immune deviation in patients with multiple sclerosis

The outcome of immune responses can be predicted by the lymphokine production pattern of the participating cells. Cytokines of the T helper type 1 (Th1) cells mediate inflammatory responses and delayed-type hypersensitivity (DTH), whereas Th2-like T cells predominantly produce cytokines, which stimulate antibody production by B cells. Immunoregulatory therapy of autoimmune diseases with unknown antigens may be achieved by inhibiting the production of inflammatory cytokines and induction of protective cytokines of Th2-like T cells. To determine the immunoregulatory capacity of the phosphodiesterase inhibitor pentoxifylline (PTX), which is known to suppress the production of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), this drug was used in mitogen and antigen-stimulated lymphocyte cultures as well as in patients with multiple sclerosis. PTX significantly decreased TNF-alpha and interleukin-12 (IL-12), whereas it increased IL-4 and IL-10 production. In addition, PTX inhibited cell proliferation, which was associated with a marked reduction in CD25 (IL-2 receptor alpha-chain) and CD54 (intercellular adhesion molecule-1; ICAM-1) expression. Increasing doses of PTX significantly reduced TNF-alpha and IL-12 mRNA expression of blood mononuclear cells, but increased IL-4 and IL-10 expression in eight patients with relapsing-remitting multiple sclerosis. These results indicate that PTX modulates immune reactions favouring a Th2-like response and may therefore be useful for the treatment of autoimmune diseases with a dominant Th1-like T cell response.

Elevated Levels of Circulating Adhesion Molecules in IDDM Patients and in Subjects at Risk for IDDM

Serum levels of recently discovered circulating forms of adhesion molecules, ICAM-1 and L-selectin, were found to be elevated in IDDM patients and in subjects at risk for developing IDDM compared with 100 normal, nondiabetic blood donors. Both adhesion molecules were determined by sandwich ELISA. Serum concentrations of either clCAM-1 or cL-selectin were >2SD of normal mean in 10 of 14 recent-onset IDDM patients (P < 0.05). Serum levels of clCAM-1 and cL-selectin did not correlate. In first-degree relatives, elevated adhesion molecule levels were observed in the 6 ICA+ individuals and in the ICA− individuals all (n = 14) with a genetic risk of IDDM (sharing HLA-DR3 and/or -DR4− with the diabetic relative) but not in the HLA-DR3− and/or -DR4− relatives (n = 13). We conclude that elevated clCAM-1 and cL-selectin levels occur independently of ICA status and probably reflect ongoing immune processes in recent-onset IDDM patients and first-degree relatives at risk for IDDM.

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.

Chemokines and Incident Coronary Heart Disease Results From the MONICA/KORA Augsburg Case-Cohort Study, 1984–2002

Objectives—The chemokines monocyte chemoattractant protein-1 (MCP-1/CCL2), interleukin-8 (IL-8/CXCL8), and interferon-&ggr;–inducible protein-10 (IP-10/CXCL10) have been reported to be involved in the development of atherosclerosis and type 2 diabetes. The aim of this study was to assess whether elevated systemic levels of these chemokines precede coronary events. Methods and Results—We investigated MCP-1, IL-8, and IP-10 serum levels in a case-cohort design based on data from 381 individuals (294 men, 87 women) with and 1977 individuals (1006 men, 971 women) without incident coronary heart disease (CHD) from the prospective, population-based MONICA/KORA Augsburg study (1984 to 2002). The mean follow-up time was 11.0 years. Baseline concentrations were significantly higher in cases compared with noncases (P≤0.001 for all chemokines). MCP-1 and IL-8 remained associated with CHD risk after adjustment for age, sex, and survey with hazard ratios (95% confidence intervals) comparing extreme tertiles of 1.39 (1.05 to 1.84) for MCP-1 and 1.48 (1.10 to 1.99) for IL-8. However, adjustment for further cardiovascular and immunologic risk factors attenuated the observed associations, and they became nonsignificant. Conclusions—Elevated systemic levels of the chemokines MCP-1, IL-8, and IP-10 precede CHD but do not represent independent risk factors. Thus, the associations are less pronounced than previously shown for type 2 diabetes.

IL6 gene promoter polymorphisms and type 2 diabetes: joint analysis of individual participants' data from 21 studies

Several lines of evidence indicate a causal role of the cytokine interleukin (IL)-6 in the development of type 2 diabetes in humans. Two common polymorphisms in the promoter of the IL-6 encoding gene IL6, −174G>C (rs1800795) and −573G>C (rs1800796), have been investigated for association with type 2 diabetes in numerous studies but with results that have been largely equivocal. To clarify the relationship between the two IL6 variants and type 2 diabetes, we analyzed individual data on >20,000 participants from 21 published and unpublished studies. Collected data represent eight different countries, making this the largest association analysis for type 2 diabetes reported to date. The GC and CC genotypes of IL6 −174G>C were associated with a decreased risk of type 2 diabetes (odds ratio 0.91, P = 0.037), corresponding to a risk modification of nearly 9%. No evidence for association was found between IL6 −573G>C and type 2 diabetes. The observed association of the IL6 −174 C-allele with a reduced risk of type 2 diabetes provides further evidence for the hypothesis that immune mediators are causally related to type 2 diabetes; however, because the association is borderline significant, additional data are still needed to confirm this finding.

Subclinical inflammation and diabetic polyneuropathy: MONICA/KORA Survey F3 (Augsburg, Germany).

OBJECTIVE Subclinical inflammation represents a risk factor of type 2 diabetes and several diabetes complications, but data on diabetic neuropathies are scarce. Therefore, we investigated whether circulating concentrations of acute-phase proteins, cytokines, and chemokines differ among diabetic patients with or without diabetic polyneuropathy. RESEARCH DESIGN AND METHODS We measured 10 markers of subclinical inflammation in 227 type 2 diabetic patients with diabetic polyneuropathy who participated in the population-based MONICA/KORA Survey F3 (2004–2005; Augsburg, Germany). Diabetic polyneuropathy was diagnosed using the Michigan Neuropathy Screening Instrument (MNSI). RESULTS After adjustment for multiple confounders, high levels of C-reactive protein and interleukin (IL)-6 were most consistently associated with diabetic polyneuropathy, high MNSI score, and specific neuropathic deficits, whereas some inverse associations were seen for IL-18. CONCLUSIONS This study shows that subclinical inflammation is associated with diabetic polyneuropathy and neuropathic impairments. This association appears rather specific because only certain immune mediators and impairments are involved.

Altered chemokine levels in individuals at risk of Type 1 diabetes mellitus

Aims  The hypothesis was tested in an exploratory study that individuals at high risk of developing Type 1 diabetes mellitus have altered systemic levels of cytokines and chemokines.