Combined effect of inflammatory gene polymorphisms and the risk of ischemic stroke in a prospective cohort of subjects with type 2 diabetes: a Go-DARTS study

Predicting the risk of stroke among patients with type 2 diabetes: a systematic review and meta-analysis of C-statistics

OBJECTIVE

Stroke is a major cause of disability and death worldwide. People with diabetes are at a twofold to fivefold increased risk for stroke compared with people without diabetes. This study systematically reviews the literature on available stroke prediction models specifically developed or validated in patients with diabetes and assesses their predictive performance through meta-analysis.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

A detailed search was performed in MEDLINE, PubMed and EMBASE (from inception to 22 April 2019) to identify studies describing stroke prediction models.

ELIGIBILITY CRITERIA

All studies that developed stroke prediction models in populations with diabetes were included.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently identified eligible articles and extracted data. Random effects meta-analysis was used to obtain a pooled C-statistic.

RESULTS

Our search retrieved 26 202 relevant papers and finally yielded 38 stroke prediction models, of which 34 were specifically developed for patients with diabetes and 4 were developed in general populations but validated in patients with diabetes. Among the models developed in those with diabetes, 9 reported their outcome as stroke, 23 reported their outcome as composite cardiovascular disease (CVD) where stroke was a component of the outcome and 2 did not report stroke initially as their outcome but later were validated for stroke as the outcome in other studies. C-statistics varied from 0.60 to 0.92 with a median C-statistic of 0.71 (for stroke as the outcome) and 0.70 (for stroke as part of a composite CVD outcome). Seventeen models were externally validated in diabetes populations with a pooled C-statistic of 0.68.

CONCLUSIONS

Overall, the performance of these diabetes-specific stroke prediction models was not satisfactory. Research is needed to identify and incorporate new risk factors into the model to improve models' predictive ability and further external validation of the existing models in diverse population to improve generalisability.

Variants in the Atherogenic ALOX5AP, THBD, and KNG1 Genes Potentiate the Risk of Ischemic Stroke via a Genetic Main Effect and Epistatic Interactions in a Chinese Population

BACKGROUND

Ischemic stroke (IS) is a multifactorial disease that displays a strong genetic predisposition. However, the genetic architecture of IS has yet to be fully elucidated. It was hypothesized that epistasis between genes in multiple atherothrombotic pathways may play a vital role in determining the susceptibility to IS. The aim of the present study was to investigate the contributions of the hypothesized genetic factors to IS and the interactions between these genetic factors in a Chinese population.

METHODS

In this study, 351 cases with IS and 417 control subjects from a Chinese population were genotyped for single-nucleotide polymorphisms (SNPs) in 12 genes hypothesized to be involved in atherosclerosis, coagulation, and related pathways. We examined SNP main effects and epistatic interactions between these polymorphic loci.

RESULTS

rs710446 of the KNG1 gene was associated with IS susceptibility based on an additive genetic model (rs710446: P = .012; odds ratio [OR], 1.247; 95% confidence interval [CI], 1.050-1.481) after adjusting for covariates. Furthermore, an epistatic interaction between the ALOX5AP, THBD, and KNG1 gene was also identified in association with stroke susceptibility (P < .001 after 1000 permutations). Based on the chi-squared test, the OR of the high-risk combination of the three-locus model increased the risk of IS by 2.53-fold (95% CI, 1.60-4.01; P < .0001).

CONCLUSIONS

Our findings support the association of the epistatic interactions of ALOX5AP, THBD, and KNG1 and present novel evidence for the main effect of KNG1 gene on IS susceptibility, suggesting a modulation of stroke risk by a genetic main effect and gene-gene interactions.

Circulating inflammatory markers and the risk of vascular complications and mortality in people with type 2 diabetes and cardiovascular disease or risk factors: the ADVANCE study

C-reactive protein (CRP), fibrinogen, and interleukin-6 (IL-6) are associated with cardiovascular disease (CVD) and death in general populations. However, studies of these factors in type 2 diabetes are limited. We studied their associations with the risk of major macrovascular events, microvascular complications, and mortality in patients with type 2 diabetes who participated in the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) Study. Plasma CRP, fibrinogen, and IL-6 levels were determined in a case-cohort study (n = 3,865) nested within the 11,140 men and women with type 2 diabetes and baseline CVD or risk factors in the ADVANCE Study. All three biomarkers of inflammation were associated with an increased risk of macrovascular events and death in analyses adjusted for age, sex, and treatment groups. After further adjustment, only IL-6 was an independent predictor of macrovascular events (hazard ratio per SD increase 1.37 [95% CI 1.24-1.51]) and death (1.35 [1.23-1.49]). IL-6 significantly improved the prediction of macrovascular events and death. After adjustment, none of the markers predicted microvascular complications. We conclude that IL-6 levels, but not CRP or fibrinogen levels, add significantly to the prediction of macrovascular events and mortality in individuals with type 2 diabetes who have baseline CVD or risk factors.

Study design of DIACORE (DIAbetes COhoRtE) - a cohort study of patients with diabetes mellitus type 2

Background

Diabetes mellitus type 2 (DM2) is highly associated with increased risk for chronic kidney disease (CKD), end stage renal disease (ESRD) and cardiovascular morbidity. Epidemiological and genetic studies generate hypotheses for innovative strategies in DM2 management by unravelling novel mechanisms of diabetes complications, which is essential for future intervention trials. We have thus initiated the DIAbetes COhoRtE study (DIACORE).

Methods

DIACORE is a prospective cohort study aiming to recruit 6000 patients of self-reported Caucasian ethnicity with prevalent DM2 for at least 10 years of follow-up. Study visits are performed in University-based recruiting clinics in Germany using standard operating procedures. All prevalent DM2 patients in outpatient clinics surrounding the recruiting centers are invited to participate. At baseline and at each 2-year follow-up examination, patients are subjected to a core phenotyping protocol. This includes a standardized online questionnaire and physical examination to determine incident micro- and macrovascular DM2 complications, malignancy and hospitalization, with a primary focus on renal events. Confirmatory outcome information is requested from patient records. Blood samples are obtained for a centrally analyzed standard laboratory panel and for biobanking of aliquots of serum, plasma, urine, mRNA and DNA for future scientific use. A subset of the cohort is subjected to extended phenotyping, e.g. sleep apnea screening, skin autofluorescence measurement, non-mydriatic retinal photography and non-invasive determination of arterial stiffness.

Discussion

DIACORE will enable the prospective evaluation of factors involved in DM2 complication pathogenesis using high-throughput technologies in biosamples and genetic epidemiological studies.

Paradoxical lower serum triglyceride levels and higher type 2 diabetes mellitus susceptibility in obese individuals with the PNPLA3 148M variant

Background

Obesity is highly associated with elevated serum triglycerides, hepatic steatosis and type 2 diabetes (T2D). The I148M (rs738409) genetic variant of patatin-like phospholipase domain-containing 3 gene (PNPLA3) is known to modulate hepatic triglyceride accumulation, leading to steatosis. No association between PNPLA3 I148M genotype and T2D in Europeans has been reported. Aim of this study is to examine the relationship between PNPLA3 I148M genotypes and serum triglycerides, insulin resistance and T2D susceptibility by testing a gene-environment interaction model with severe obesity.

Methods and Findings

PNPLA3 I148M was genotyped in a large obese cohort, the SOS study (n = 3,473) and in the Go-DARTS (n = 15,448), a T2D case-control study. Metabolic parameters were examined across the PNPLA3 I148M genotypes in participants of the SOS study at baseline and at 2- and 10-year follow up after bariatric surgery or conventional therapy. The associations with metabolic parameters were validated in the Go-DARTS study. Serum triglycerides were found to be lower in the PNPLA3 148M carriers from the SOS study at baseline and from the Go-DARTS T2D cohort. An increased risk for T2D conferred by the 148M allele was found in the SOS study (O.R. 1.09, 95% C.I. 1.01-1.39, P = 0.040) and in severely obese individuals in the Go-DARTS study (O.R. 1.37, 95% C.I. 1.13-1.66, P = 0.001). The 148M allele was no longer associated with insulin resistance or T2D after bariatric surgery in the SOS study and no association with the 148M allele was observed in the less obese (BMI<35) individuals in the Go-DARTS study (P for interaction  = 0.002). This provides evidence for the obesity interaction with I48M allele and T2D risk in a large-scale cross-sectional and a prospective interventional study.

Conclusions

Severely obese individuals carrying the PNPLA3 148M allele have lower serum triglyceride levels, are more insulin resistant and more susceptible to T2D. This study supports the hypothesis that obesity-driven hepatic lipid accumulation may contribute to T2D susceptibility.

Excess risk of mortality and cardiovascular events associated with smoking among patients with diabetes: meta-analysis of observational prospective studies

BACKGROUND

Numerous studies have demonstrated that both smoking and diabetes are risk factors for mortality and caused-specific cardiovascular events. However, few studies systematically investigated to what extent the excess risk could be attributed to smoking among diabetic patients.

METHODS

Literature references were searched up to April 2011 in MEDLINE and EMBASE, supplemented by manual searches. Inclusion criteria were prospective cohort studies, assessment of the association between smoking and total mortality, cardiovascular death, incidence of coronary heart disease (CHD), stroke and myocardial infarction (MI) in diabetic patients.

RESULTS

Of 3758 studies in the literature searched, 46 were eligible with approximately 130,000 diabetic patients. The relative risk (RR) comparing smokers with nonsmokers was 1.48[95% confidential interval (CI): 1.34-1.64] for total mortality (27 studies), 1.36(1.22-1.52) for cardiovascular mortality (9 studies), 1.54(1.31-1.82) for CHD (13 studies), 1.44(1.28-1.61) for stroke (9 studies) and 1.52(1.25-1.83) for MI (7 studies). Furthermore, the excess risk was observed among former and current smokers with a greater risk in current smokers. Subgroup analysis showed that the increased risk appeared to be consistent regardless of several study characteristics with the RRs ranging from 1.31 to 1.94 for all-cause mortality, 1.37 to 2.28 for CHD, 1.21 to 1.87 for stroke, 1.13 to 1.74 for cardiovascular mortality and 1.15 to 2.01 for MI.

CONCLUSION

Smoking amplified the risk of mortality as well as cardiovascular events and the effect size for CHD appeared to be higher than other events in diabetic patients. Moreover, a trend of decreasing risk was observed among smoking quitters.

Variants in the inflammatory IL6 and MPO genes modulate stroke susceptibility through main effects and gene-gene interactions

There is substantial evidence that inflammation within the central nervous system contributes to stroke risk and recovery. Inflammatory conditions increase stroke risk, and the inflammatory response is of major importance in recovery and healing processes after stroke. We investigated the role of inflammatory genes IL1B, IL6, MPO, and TNF in stroke susceptibility and recovery in a population sample of 672 patients and 530 controls, adjusting for demographic, clinical and lifestyle risk factors, and stroke severity parameters. We also considered the likely complexity of inflammatory mechanisms in stroke, by assessing the combined effects of multiple genes. Two interleukin 6 (IL6) and one myeloperoxidase (MPO) single-nucleotide polymorphisms were significantly associated with stroke risk (0.022<(corrected)P<0.042), highlighting gene variants of low to moderate effect in stroke risk. An epistatic interaction between the IL6 and MPO genes was also identified in association with stroke susceptibility (P=0.031 after 1,000 permutations). In a subset of 546 patients, one IL6 haplotype was associated with stroke outcome at 3 months ((corrected)P=0.024), an intriguing finding warranting further validation. Our findings support the association of the IL6 gene and present novel evidence for the involvement of MPO in stroke susceptibility, suggesting a modulation of stroke risk by main gene effects, clinical and lifestyle factors, and gene-gene interactions.