Anti-inflammatory therapy in type 1 diabetes

Type 1 diabetes (T1D) is a multi-factorial, organ-specific autoimmune disease in genetically susceptible individuals, which is characterized by a selective and progressive loss of insulin-producing β-cells. Cells mediating innate as well as adaptive immunity infiltrate pancreatic islets, thereby generating an aberrant inflammatory process called insulitis that can be mirrored by a pathologic autoantibody production and autoreactive T-cells. In tight cooperation with infiltrating innate immune cells, which secrete high levels of pro-inflammatory cytokines like IL-1β, TNFα, and INFγ effector T-cells trigger the fatal destruction process of β-cells. There is ongoing discussion on the contribution of inflammation in T1D pathogenesis, ranging from a bystander reaction of autoimmunity to a dysregulation of immune responses that initiate inflammatory processes and thereby actively promoting β-cell death. Here, we review recent advances in anti-inflammatory interventions in T1D animal models and preclinical studies and discuss their mode of action as well as their capacity to interfere with T1D development.

Large-scale association analysis provides insights into the genetic architecture and pathophysiology of type 2 diabetes

To extend understanding of the genetic architecture and molecular basis of type 2 diabetes (T2D), we conducted a meta-analysis of genetic variants on the Metabochip, including 34,840 cases and 114,981 controls, overwhelmingly of European descent. We identified ten previously unreported T2D susceptibility loci, including two showing sex-differentiated association. Genome-wide analyses of these data are consistent with a long tail of additional common variant loci explaining much of the variation in susceptibility to T2D. Exploration of the enlarged set of susceptibility loci implicates several processes, including CREBBP-related transcription, adipocytokine signaling and cell cycle regulation, in diabetes pathogenesis.

Large-scale association analyses identify new loci influencing glycemic traits and provide insight into the underlying biological pathways

Through genome-wide association meta-analyses of up to 133,010 individuals of European ancestry without diabetes, including individuals newly genotyped using the Metabochip, we have increased the number of confirmed loci influencing glycemic traits to 53, of which 33 also increase type 2 diabetes risk (q < 0.05). Loci influencing fasting insulin concentration showed association with lipid levels and fat distribution, suggesting impact on insulin resistance. Gene-based analyses identified further biologically plausible loci, suggesting that additional loci beyond those reaching genome-wide significance are likely to represent real associations. This conclusion is supported by an excess of directionally consistent and nominally significant signals between discovery and follow-up studies. Functional analysis of these newly discovered loci will further improve our understanding of glycemic control.

Combination of low free testosterone and low vitamin D predicts mortality in older men referred for coronary angiography

CONTEXT

Low levels of 25-hydroxyvitamin D [25(OH)D] and free testosterone (FT) are both associated with increased mortality. Experimental studies show a complex interplay of vitamin D and androgen metabolism suggesting that a deficiency of both hormones may be associated with a particularly adverse clinical outcome.

OBJECTIVE

To evaluate the impact of parallel FT and 25(OH)D deficiency in a large cohort of older men.

DESIGN

We measured total testosterone (TT), sex hormone-binding globulin and 25(OH)D levels in 2069 men who were routinely referred for coronary angiography (1997-2000).

MAIN OUTCOME MEASURES

Cox proportional hazard ratios (HRs) (with 95% confidence intervals) for mortality from all causes, cardiovascular and noncardiovascular causes according to combined deficiency of FT and 25(OH)D.

RESULTS

In multivariate-adjusted analyses, we found an increased risk for all-cause mortality, cardiovascular and noncardiovascular mortality for men in the lowest FT [HR 1·26 (1·03-1·54), 1·24 (0·96-1·60) and 1·39 (1·00-1·93), respectively] and 25(OH)D quartile [HR 1·77 (1·47-2·13), 1·65 (1·29-2·10) and 1·89 (1·38-2·60) respectively] compared with men in higher FT and 25(OH)D quartiles. There was no independent association of TT levels with mortality. Multivariate-adjusted HRs progressively increased with the number of hormones (FT and 25(OH)D) in the lowest quartile [0 vs 2 hormone deficiencies: 2·11 (1·60-2·79) for all cause, 1·77 (1·23-2·55) for cardiovascular and 2·33 (1·45-3·47) for noncardiovascular mortality, respectively].

CONCLUSION

A combined deficiency of FT and 25(OH)D is significantly associated with fatal events in a large cohort of men referred for coronary angiography.

Guthrie card methylomics identifies temporally stable epialleles that are present at birth in humans

A major concern in common disease epigenomics is distinguishing causal from consequential epigenetic variation. One means of addressing this issue is to identify the temporal origins of epigenetic variants via longitudinal analyses. However, prospective birth-cohort studies are expensive and time consuming. Here, we report DNA methylomics of archived Guthrie cards for the retrospective longitudinal analyses of in-utero-derived DNA methylation variation. We first validate two methodologies for generating comprehensive DNA methylomes from Guthrie cards. Then, using an integrated epigenomic/genomic analysis of Guthrie cards and follow-up samplings, we identify interindividual DNA methylation variation that is present both at birth and 3 yr later. These findings suggest that disease-relevant epigenetic variation could be detected at birth, i.e., before overt clinical disease. Guthrie card methylomics offers a potentially powerful and cost-effective strategy for studying the dynamics of interindividual epigenomic variation in a range of common human diseases.

Circulating dopamine and C-peptide levels in fasting nondiabetic hypertensive patients: the Graz Endocrine Causes of Hypertension study

OBJECTIVE

Accumulating evidence supports a potential role for dopamine in the regulation of insulin secretion. We examined the association between circulating dopamine and C-peptide concentrations using data from the Graz Endocrine Causes of Hypertension (GECOH) study.

RESEARCH DESIGN AND METHODS

After 12 h of fasting, we measured plasma dopamine and serum C-peptide levels and established determining factors of insulin secretion in 201 nondiabetic hypertensive patients (mean age 48.1 ± 16.0 years; 61.7% women).

RESULTS

Mean dopamine and C-peptide concentration were 33.4 ± 38.6 pg/mL and 3.1 ± 2.7 ng/mL, respectively. A strong and inverse correlation was observed between dopamine and C-peptide levels (r = -0.423, P < 0.001). There was no significant relationship between C-peptide, plasma epinephrine, and norepinephrine. C-peptide levels decreased steadily and significantly from tertile 1 of dopamine (3.6 ng/mL [95% CI 2.9-4.1]) to tertile 3 (1.6 ng/mL [1.5-2.7], P < 0.001) after multivariate adjustment.

CONCLUSIONS

The inverse association between dopamine and C-peptide highlights the need to evaluate whether dopamine could be effective for modulating endocrine pancreatic function.

Glycotoxin and autoantibodies are additive environmentally determined predictors of type 1 diabetes: a twin and population study

In type 1 diabetes, diabetes-associated autoantibodies, including islet cell antibodies (ICAs), reflect adaptive immunity, while increased serum N(ε)-carboxymethyl-lysine (CML), an advanced glycation end product, is associated with proinflammation. We assessed whether serum CML and autoantibodies predicted type 1 diabetes and to what extent they were determined by genetic or environmental factors. Of 7,287 unselected schoolchildren screened, 115 were ICA(+) and were tested for baseline CML and diabetes autoantibodies and followed (for median 7 years), whereas a random selection (n = 2,102) had CML tested. CML and diabetes autoantibodies were determined in a classic twin study of twin pairs discordant for type 1 diabetes (32 monozygotic, 32 dizygotic pairs). CML was determined by enzyme-linked immunosorbent assay, autoantibodies were determined by radioimmunoprecipitation, ICA was determined by indirect immunofluorescence, and HLA class II genotyping was determined by sequence-specific oligonucleotides. CML was increased in ICA(+) and prediabetic schoolchildren and in diabetic and nondiabetic twins (all P < 0.001). Elevated levels of CML in ICA(+) children were a persistent, independent predictor of diabetes progression, in addition to autoantibodies and HLA risk. In twins model fitting, familial environment explained 75% of CML variance, and nonshared environment explained all autoantibody variance. Serum CML, a glycotoxin, emerged as an environmentally determined diabetes risk factor, in addition to autoimmunity and HLA genetic risk, and a potential therapeutic target.

Duration of type 2 diabetes strongly predicts all-cause and cardiovascular mortality in people referred for coronary angiography

OBJECTIVE

Type 2 diabetes represents a major cardiovascular risk factor. However, few studies have addressed the impact of the disease duration on mortality. Thus, we aimed to investigate the predictive value of diabetes duration for all-cause and cardiovascular mortality in subjects undergoing coronary angiography.

METHODS

We studied 2455 participants of the LUdwigshafen RIsk and Cardiovascular health study (1768 males/687 females). They had a mean ± standard deviation (SD) age of 63.1 ± 9.0 years (range: 40.0-79.9) and a mean ± SD body mass index of 27.7 ± 4.0 kg/m(2). 704 subjects were newly diagnosed with type 2 diabetes according to the 2010 criteria of the American Diabetes Association and 446 subjects had a known history of type 2 diabetes. The mean ± SD duration of the follow-up for all-cause and cardiovascular mortality was 7.4 ± 2.3 years.

RESULTS

A total of 543 deaths occurred during the follow-up. Among these, 343 were accounted for by cardiovascular diseases. The duration of type 2 diabetes was strongly and positively correlated with all-cause and cardiovascular mortality (both P<0.001). The multivariate adjusted hazard ratios (95% confidence intervals) for cardiovascular mortality compared to subjects without diabetes were 1.76 (1.34-2.32), 2.86 (2.00-4.08), 2.96 (1.85-4.74), and 4.55 (3.24-6.39) for subjects with new onset type 2 diabetes and subjects with known type 2 diabetes (duration ≤ 5, >5 and ≤ 10, >10 years), respectively.

CONCLUSIONS

The data emphasise the need to consider the diabetes duration for the prediction of mortality in subjects at intermediate to high cardiovascular risk.

A genome-wide association search for type 2 diabetes genes in African Americans

African Americans are disproportionately affected by type 2 diabetes (T2DM) yet few studies have examined T2DM using genome-wide association approaches in this ethnicity. The aim of this study was to identify genes associated with T2DM in the African American population. We performed a Genome Wide Association Study (GWAS) using the Affymetrix 6.0 array in 965 African-American cases with T2DM and end-stage renal disease (T2DM-ESRD) and 1029 population-based controls. The most significant SNPs (n = 550 independent loci) were genotyped in a replication cohort and 122 SNPs (n = 98 independent loci) were further tested through genotyping three additional validation cohorts followed by meta-analysis in all five cohorts totaling 3,132 cases and 3,317 controls. Twelve SNPs had evidence of association in the GWAS (P<0.0071), were directionally consistent in the Replication cohort and were associated with T2DM in subjects without nephropathy (P<0.05). Meta-analysis in all cases and controls revealed a single SNP reaching genome-wide significance (P<2.5×10(-8)). SNP rs7560163 (P = 7.0×10(-9), OR (95% CI) = 0.75 (0.67-0.84)) is located intergenically between RND3 and RBM43. Four additional loci (rs7542900, rs4659485, rs2722769 and rs7107217) were associated with T2DM (P<0.05) and reached more nominal levels of significance (P<2.5×10(-5)) in the overall analysis and may represent novel loci that contribute to T2DM. We have identified novel T2DM-susceptibility variants in the African-American population. Notably, T2DM risk was associated with the major allele and implies an interesting genetic architecture in this population. These results suggest that multiple loci underlie T2DM susceptibility in the African-American population and that these loci are distinct from those identified in other ethnic populations.

Relationship between plasma aldosterone concentration and soluble cellular adhesion molecules in patients referred to coronary angiography

OBJECTIVE

Evidence is emerging that aldosterone contributes to the development and progression of atherosclerosis and cardiovascular disease. Little is known, however, regarding an association between circulating aldosterone levels and soluble cellular adhesion molecules in humans.

METHODS

We investigated the relationship between plasma aldosterone concentration (PAC) and soluble cellular adhesion molecules in a large cohort of patients referred to coronary angiography. After exclusion of patients with ongoing mineralocorticoid receptor blocker use, oral contraceptive or hormone replacement therapy, 1,733 patients (mean age: 62.5±10.8 years; 26.4%% women; mean PAC: 101.5±93.5 pg/mL) remained eligible for analyses.

RESULTS

Pearson correlation analysis as well as age and gender adjusted partial correlation analysis revealed a positive association between PAC and soluble (s) E-, L- and P-selectin levels but not with sICAM-1 and sVCAM-1, respectively. In multivariate adjusted analyses of covariance (ANCOVA) sE- (p=0.026), sL- (p=0.049) and sP-selectin (p<0.001) levels increased steadily from the first (reference) to the third gender-specific tertile of PAC. No significant variation across PAC tertiles was found for sICAM-1 (p=0.767) and sVCAM1 (p=0.425) levels, respectively. Finally, multivariate regression analyses revealed circulating aldosterone as an important predictor for soluble selectin levels.

CONCLUSION

Our findings in a large cohort of patients indicate that upregulation of selectins might represent a novel mechanism of aldosterone mediated development and progression of atherosclerosis. In view of aldosterone as a novel cardiovascular risk factor independent of angiotensin II, our findings warrant further interventional studies which should evaluate anti-atherosclerotic effects of aldosterone blocking treatment strategies in humans.

Additional use of glycated hemoglobin for diagnosis of type 2 diabetes in people undergoing coronary angiography reveals a subgroup at increased cardiovascular risk

OBJECTIVE

To study the prognosis of people with newly diagnosed type 2 diabetes as per the American Diabetes Association (ADA) 2010 definition but without diabetes as per the ADA 2009 definition.

RESEARCH DESIGN AND METHODS

A total of 2,002 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study without a history of diabetes were studied.

RESULTS

During the follow-up of a mean duration ± SD of 7.7 ± 2.0 years, 346 people died (202 cardiovascular deaths). Subjects with type 2 diabetes as per the ADA 2009 definition (n = 468) had significantly increased all-cause and cardiovascular mortality compared with people without diabetes as per the ADA 2010 definition (both P ≤ 0.003). Subjects with type 2 diabetes as per the ADA 2010 definition but without diabetes as per the ADA 2009 definition (n = 150) were at significantly increased risk to die of cardiovascular diseases (P = 0.029).

CONCLUSIONS

Use of the ADA 2010 diabetes definition may be instrumental in improving cardiovascular risk stratification in people undergoing coronary angiography.

Genetic analysis of adult-onset autoimmune diabetes

OBJECTIVE

In contrast with childhood-onset type 1 diabetes, the genetics of autoimmune diabetes in adults are not well understood. We have therefore investigated the genetics of diabetes diagnosed in adults positive for autoantibodies.

RESEARCH DESIGN AND METHODS

GAD autoantibodies (GADAs), insulinoma-associated antigen-2 antibodies (IA-2As), and islet cell autoantibodies were measured at time of diagnosis. Autoantibody-positive diabetic subjects (n = 1,384) and population-based control subjects (n = 2,235) were genotyped at 20 childhood-onset type 1 diabetes loci and FCRL3, GAD2, TCF7L2, and FTO.

RESULTS

PTPN22 (1p13.2), STAT4 (2q32.2), CTLA4 (2q33.2), HLA (6p21), IL2RA (10p15.1), INS (11p15.5), ERBB3 (12q13.2), SH2B3 (12q24.12), and CLEC16A (16p13.13) were convincingly associated with autoimmune diabetes in adults (P ≤ 0.002), with consistent directions of effect as reported for pediatric type 1 diabetes. No evidence of an HLA-DRB1*03/HLA-DRB1*04 (DR3/4) genotype effect was obtained (P = 0.55), but it remained highly predisposing (odds ratio 26.22). DR3/4 was associated with a lower age at diagnosis of disease, as was DR4 (P = 4.67 × 10(-6)) but not DR3. DR3 was associated with GADA positivity (P = 6.03 × 10(-6)) but absence of IA-2A (P = 3.22 × 10(-7)). DR4 was associated with IA-2A positivity (P = 5.45 × 10(-6)).

CONCLUSIONS

Our results are consistent with the hypothesis that the genetics of autoimmune diabetes in adults and children are differentiated by only relatively few age-dependent genetic effects. The slower progression toward autoimmune insulin deficiency in adults is probably due to a lower genetic load overall combined with subtle variation in the HLA class II gene associations and autoreactivity.

Identification of type 1 diabetes-associated DNA methylation variable positions that precede disease diagnosis

Monozygotic (MZ) twin pair discordance for childhood-onset Type 1 Diabetes (T1D) is ∼50%, implicating roles for genetic and non-genetic factors in the aetiology of this complex autoimmune disease. Although significant progress has been made in elucidating the genetics of T1D in recent years, the non-genetic component has remained poorly defined. We hypothesized that epigenetic variation could underlie some of the non-genetic component of T1D aetiology and, thus, performed an epigenome-wide association study (EWAS) for this disease. We generated genome-wide DNA methylation profiles of purified CD14⁺ monocytes (an immune effector cell type relevant to T1D pathogenesis) from 15 T1D–discordant MZ twin pairs. This identified 132 different CpG sites at which the direction of the intra-MZ pair DNA methylation difference significantly correlated with the diabetic state, i.e. T1D–associated methylation variable positions (T1D–MVPs). We confirmed these T1D–MVPs display statistically significant intra-MZ pair DNA methylation differences in the expected direction in an independent set of T1D–discordant MZ pairs (P = 0.035). Then, to establish the temporal origins of the T1D–MVPs, we generated two further genome-wide datasets and established that, when compared with controls, T1D–MVPs are enriched in singletons both before (P = 0.001) and at (P = 0.015) disease diagnosis, and also in singletons positive for diabetes-associated autoantibodies but disease-free even after 12 years follow-up (P = 0.0023). Combined, these results suggest that T1D–MVPs arise very early in the etiological process that leads to overt T1D. Our EWAS of T1D represents an important contribution toward understanding the etiological role of epigenetic variation in type 1 diabetes, and it is also the first systematic analysis of the temporal origins of disease-associated epigenetic variation for any human complex disease.

Type 1 diabetes (T1D) is a complex autoimmune disease affecting >30 million people worldwide. It is caused by a combination of genetic and non-genetic factors, leading to destruction of insulin-secreting cells. Although significant progress has recently been made in elucidating the genetics of T1D, the non-genetic component has remained poorly defined. Epigenetic modifications, such as methylation of DNA, are indispensable for genomic processes such as transcriptional regulation and are frequently perturbed in human disease. We therefore hypothesized that epigenetic variation could underlie some of the non-genetic component of T1D aetiology, and we performed a genome-wide DNA methylation analysis of a specific subset of immune cells (monocytes) from monozygotic twins discordant for T1D. This revealed the presence of T1D–specific methylation variable positions (T1D–MVPs) in the T1D–affected co-twins. Since these T1D–MVPs were found in MZ twins, they cannot be due to genetic differences. Additional experiments revealed that some of these T1D–MVPs are found in individuals before T1D diagnosis, suggesting they arise very early in the process that leads to overt T1D and are not simply due to post-disease associated factors (e.g. medication or long-term metabolic changes). T1D–MVPs may thus potentially represent a previously unappreciated, and important, component of type 1 diabetes risk.

Investigation of 95 variants identified in a genome-wide study for association with mortality after acute coronary syndrome

Background

Genome-wide association studies (GWAS) have identified new candidate genes for the occurrence of acute coronary syndrome (ACS), but possible effects of such genes on survival following ACS have yet to be investigated.

Methods

We examined 95 polymorphisms in 69 distinct gene regions identified in a GWAS for premature myocardial infarction for their association with post-ACS mortality among 811 whites recruited from university-affiliated hospitals in Kansas City, Missouri. We then sought replication of a positive genetic association in a large, racially diverse cohort of myocardial infarction patients (N = 2284) using Kaplan-Meier survival analyses and Cox regression to adjust for relevant covariates. Finally, we investigated the apparent association further in 6086 additional coronary artery disease patients.

Results

After Cox adjustment for other ACS risk factors, of 95 SNPs tested in 811 whites only the association with the rs6922269 in MTHFD1L was statistically significant, with a 2.6-fold mortality hazard (P = 0.007). The recessive A/A genotype was of borderline significance in an age- and race-adjusted analysis of the entire combined cohort (N = 3095; P = 0.052), but this finding was not confirmed in independent cohorts (N = 6086).

Conclusions

We found no support for the hypothesis that the GWAS-identified variants in this study substantially alter the probability of post-ACS survival. Large-scale, collaborative, genome-wide studies may be required in order to detect genetic variants that are robustly associated with survival in patients with coronary artery disease.

The lipid accumulation product is associated with increased mortality in normal weight postmenopausal women

Lipid accumulation product (LAP) is an emerging cardiovascular risk factor, which is calculated from waist circumference (WC) and triglyceride (TG) levels. The aim of this study was to elucidate the relationship between LAP and cardiovascular mortality as well as the presence of type 2 diabetes with respect to gender-specific differences. We determined WC and fasting TG levels and the cardiovascular and metabolic phenotypes coronary artery disease (CAD), hypertension, metabolic syndrome, and diabetes mellitus in 2,279 men and 875 postmenopausal women who were routinely referred to coronary angiography. The LAP was calculated as (WC (cm)--65) × (TG (mmol/l)) for men and as (WC (cm)--58) × (TG (mmol/l)) for women. LAP levels were independently associated with congestive heart failure mortality in all postmenopausal women and with all-cause mortality in diabetic postmenopausal women but not in men. Multivariable-adjusted hazard ratios (with 95% confidence intervals) for all-cause, cardiovascular, and congestive heart failure mortality in the third compared to the first LAP tertile were 4.28 (1.94-9.44; P < 0.001), 3.47 (1.28-9.40; P = 0.015), and 10.77 (1.21-95.88; P = 0.033), respectively, in normal weight postmenopausal women, whereas no significant associations were found in men. LAP levels were highly associated with type 2 diabetes in all subjects, postmenopausal women, and men. High LAP values are predictive of mortality independently of other cardiovascular risk factors in normal weight and diabetic postmenopausal women but not in men. Type 2 diabetes (T2DM) was highly associated with LAP in women and men. Our study validates an inexpensive and simple risk profiling that may allow identifying postmenopausal women at high cardiovascular risk.

Regulation of cathepsin G reduces the activation of proinsulin-reactive T cells from type 1 diabetes patients

Autoantigenic peptides resulting from self-proteins such as proinsulin are important players in the development of type 1 diabetes mellitus (T1D). Self-proteins can be processed by cathepsins (Cats) within endocytic compartments and loaded to major histocompatibility complex (MHC) class II molecules for CD4⁺ T cell inspection. However, the processing and presentation of proinsulin by antigen-presenting cells (APC) in humans is only partially understood. Here we demonstrate that the processing of proinsulin by B cell or myeloid dendritic cell (mDC1)-derived lysosomal cathepsins resulted in several proinsulin-derived intermediates. These intermediates were similar to those obtained using purified CatG and, to a lesser extent, CatD, S, and V in vitro. Some of these intermediates polarized T cell activation in peripheral blood mononuclear cells (PBMC) from T1D patients indicative for naturally processed T cell epitopes. Furthermore, CatG activity was found to be elevated in PBMC from T1D patients and abrogation of CatG activity resulted in functional inhibition of proinsulin-reactive T cells. Our data suggested the notion that CatG plays a critical role in proinsulin processing and is important in the activation process of diabetogenic T cells.

Low free testosterone levels are associated with all-cause and cardiovascular mortality in postmenopausal diabetic women

OBJECTIVE

Hyperandrogenemia is associated with cardiovascular risk factors in women but evidence about the relationship of testosterone levels with mortality is sparse. We aimed to evaluate whether total testosterone (TT), free testosterone (FT), and sex hormone-binding globulin (SHBG) are associated with all-cause and cardiovascular mortality in a cohort of postmenopausal women.

RESEARCH DESIGN AND METHODS

We measured TT and SHBG levels in 875 postmenopausal women who were referred for coronary angiography (during 1997-2000). FT was calculated according to the Vermeulen method. The main outcome measures were Cox proportional hazard ratios (HRs) for mortality from all causes and from cardiovascular causes.

RESULTS

After a median follow-up time of 7.7 years, 179 women (20.5%) had died. There were 101 deaths due to cardiovascular disease (56.4% of all deaths). We found no association of FT, TT, and SHBG levels with mortality in all postmenopausal women. In postmenopausal diabetic women, multivariable-adjusted HRs (with 95% CIs) in the fourth compared with the first FT quartile for all-cause and cardiovascular mortality were 0.38 (0.08-0.90), P = 0.025, and 0.28 (0.08-0.90), P = 0.032, respectively. We found no association of TT and SHBG with mortality in diabetic postmenopausal women.

CONCLUSIONS

In postmenopausal diabetic women referred for coronary angiography, low FT levels are independently associated with increased all-cause and cardiovascular mortality.

Association of TCF7L2 SNPs with age at onset of type 2 diabetes and proinsulin/insulin ratio but not with glucagon-like peptide 1

BACKGROUND

Variants in TCF7L2 have been associated with the age at onset of type 2 diabetes in Mexican Americans. However, there is a lack of data on this relationship in Caucasians. Furthermore, risk alleles in TCF7L2 have been suggested to account for decreased conversion of proinsulin to insulin and decreased expression of GLP-1. We investigated the effect of the allelic variants rs1225537 and rs7903146 in TCF7L2 on the age at onset of type 2 diabetes, the plasma concentrations of proinsulin and GLP-1, and the ratio of proinsulin to insulin in a German cohort.

METHODS

We studied 3185 participants of the LUdwigshafen RIsk and Cardiovascular health (LURIC) study. Among these, 1021 subjects had type 2 diabetes. Data on age at onset of diabetes were available in 925 subjects. OGTTs were performed in a subgroup not previously known to have diabetes.

RESULTS

Carriers of the risk alleles in rs1225537 and rs7901346 had increased risk of type 2 diabetes and elevated HbA(1c) (all p < 0.001). The risk alleles were also associated with early onset of type 2 diabetes, decreased insulin secretion and markedly increased proinsulin and proinsulin to insulin ratio (all p < 0.03). GLP-1 was not significantly related to the TCF7L2 genotype.

CONCLUSIONS

Our data demonstrate that TCF7L2 variants are associated with an early age of onset of type 2 diabetes in Caucasians and affects the conversion of proinsulin to insulin. However, TCF7L2 is not consistently associated with fasting GLP-1.

Lipopolysaccharide-binding protein (LBP) is associated with total and cardiovascular mortality in individuals with or without stable coronary artery disease--results from the Ludwigshafen Risk and Cardiovascular Health Study (LURIC)

BACKGROUND

Atherosclerosis of coronary arteries is hallmarked by non-specific local inflammatory processes accompanied by a systemic response. Lipopolysaccharide-binding protein (LBP) has been suggested to be associated with coronary artery disease (CAD) in a previous study without follow-up.

PATIENTS AND METHODS

LBP plasma levels were measured in 2959 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) cohort study referred to coronary angiography at baseline between 1997 and 2000. Median follow-up time was 8.0 years. Primary and secondary end points were cardiovascular and all-cause mortality, respectively. Multivariable adjusted logistic regression analyses were conducted to investigate the role of LBP.

RESULTS

Serum LBP concentration was significantly increased in 2298 patients with angiographically confirmed CAD compared to 661 individuals without coronary atherosclerosis (6.78 μg/mL (5.46-8.84) vs. 6.13 μg/mL (5.05-7.74), respectively; p<0.001). Moreover in multivariable logistic regression analyses, adjusted for established cardiovascular risk factors and markers of systemic inflammation, LBP was a significant and independent predictor of total and cardiovascular mortality (hazard ratio (HR) for all cause mortality: 1.43, 95% CI: 1.06-1.94, p=0.024; HR for cardiovascular mortality in the 4th quartile of LBP: 1.55, 95% CI: 1.06-2.27, p=0.025).

CONCLUSION

The present results add information on LBP in CAD. The data underscore the potential importance of innate immune mechanisms for atherosclerosis. Further studies are needed to clarify the pathways between innate immune system activation and atherosclerosis.

Glycated hemoglobin predicts all-cause, cardiovascular, and cancer mortality in people without a history of diabetes undergoing coronary angiography

OBJECTIVE

Glycated hemoglobin has been suggested to be superior to fasting glucose for the prediction of vascular disease and death from any cause. The aim of the present work was to analyze and compare the predictive value of glycated hemoglobin and fasting glucose on all-cause and cause-specific mortality in subjects who underwent coronary angiography.

RESEARCH DESIGN AND METHODS

We studied 2,686 participants of the Ludwigshafen Risk and Cardiovascular health study without a history of diabetes. The majority of this cohort had coronary artery disease. Glycated hemoglobin was measured at the baseline examination. The mean (± SD) duration of the follow-up for all-cause, cardiovascular, and cancer mortality was 7.54 ± 2.1 years.

RESULTS

A total of 508 deaths occurred during the follow-up. Of those, 299 were accounted for by cardiovascular diseases and 79 by cancer. Baseline glycated hemoglobin was predictive of all-cause, cardiovascular, and cancer mortality. The multivariable-adjusted hazard ratios (HR) (95% CI) for glycated hemoglobin values of <5.0, 5.0-5.4, 5.5-5.9, 6.0-6.4, 6.5-7.4, and ≥7.5% for all-cause mortality were 1.36 (0.85-2.18), 1.00 (0.76-1.32), 1.00 (reference), 1.11 (0.88-1.41), 1.39 (1.07-1.82), and 2.15 (1.32-3.53), respectively. Similar J-shaped relationships were found between glycated hemoglobin and cardiovascular and cancer mortality. The associations of glycated hemoglobin with all-cause and cardiovascular mortality remained significant after inclusion of fasting glucose as a covariate. However, fasting glucose was not significantly related to mortality when adjusting for glycated hemoglobin.

CONCLUSIONS

Glycated hemoglobin significantly and independently of fasting glucose predicts all-cause and cardiovascular mortality in whites at intermediate to high cardiovascular risk.

Associations of plasma renin with 10-year cardiovascular mortality, sudden cardiac death, and death due to heart failure

AIMS

Renin is the key regulator of the renin-angiotensin-aldosterone system. Previous studies have reported conflicting results on the relation of plasma renin with fatal cardiovascular events. This study in a large cohort of patients sought to evaluate the association between plasma renin concentration (PRC) and cardiovascular mortality after long-term follow-up of almost 10 years.

METHODS AND RESULTS

Plasma renin concentration [median: 11.4 (6.0-24.6) pg/mL] was measured in 3303 patients (mean age: 62.7 ± 10.6 years; 30.3% women) referred to coronary angiography. After a median follow-up of 9.9 years, 554 participants (16.8%) with PRC measurement at baseline had died due to fatal cardiovascular events. Multivariable-adjusted Cox analysis revealed that when compared with participants in the lowest PRC quartile, those in the highest quartile were at increased risk of cardiovascular mortality (hazard ratio: 1.79, 95% CI 1.28-2.48). Analyses of specific causes of cardiovascular death showed that for each standard deviation increase in log-PRC there was a 22% (P = 0.006) increase in risk of sudden cardiac death and a 23% (P = 0.033) greater risk of death due to heart failure. The association of PRC with cardiovascular mortality remained stable after adjustment for established cardiovascular risk factors, ongoing antihypertensive medication, immunoreactive angiotensin II, and aldosterone levels. Age, N-terminal pro-B-type natriuretic peptide levels, coronary artery disease, the use of angiotensin-converting enzyme-inhibitors, beta-blockers, diuretics, and kidney function were important effect modifiers.

CONCLUSIONS

Plasma renin concentration is associated with long-term cardiovascular mortality in patients referred to coronary angiography. Further intervention studies should determine whether renin is a potential therapeutic target or only a marker of mortality risk in various cardiovascular risk groups.

Arginine bioavailability ratios are associated with cardiovascular mortality in patients referred to coronary angiography

OBJECTIVES

Arginine is the only source for nitric oxide (NO) synthesis. The bioavailability of NO plays a pivotal role in endothelial function and consequently in cardiovascular disease. The aim of the current study is to investigate the association of arginine bioavailability ratios with markers of endothelial function and cardiovascular mortality in patients referred to coronary angiography.

METHODS

We investigated 2236 patients recruited within the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study that were followed up for a median of 7.7 years. Arginine, ornithine and citrulline were chromatographically determined after precolumn-derivatisation followed by postcolumn continuous reaction with ninhydrin. Global arginine bioavailability (GABR) was calculated by arginine divided by the sum of ornithine plus citrulline.

RESULTS

We observed a significant rise in cardiovascular mortality with decreasing GABR and arginine to ornithine ratio quartiles. The adjusted Cox proportional HRs for GABR were 1.27 (0.88-1.83), 1.27 (0.89-1.80) and 1.75 (1.24-2.45) for the 3rd, the 2nd and the 1st quartile respectively in comparison to the 4th quartile. The HRs for the quartiles of the arginine to ornithine ratio were 1.83 (1.25-2.67), 2.17 (1.50-3.20) and 2.02 (1.39-2.92) respectively. Patients with type 2 diabetes mellitus had a significantly lower GABR than persons without diabetes (0.88 ± 0.23 vs. 0.94 ± 0.24, p<0.001). GABR was found to be inversely correlated with endothelial markers as VCAM-1 (r=-0.301, p<0.001) or ICAM-1 (r=-0.136, p<0.001).

CONCLUSIONS

GABR and the arginine to ornithine ratio are associated with markers of endothelial dysfunction and increased risk of cardiovascular mortality. Further studies are warranted to elucidate the pathobiology and clinical relevance of the arginine bioavailability ratios in cardio-metabolic diseases.