Ethnic differences in serum lipids and lipoproteins in overweight/obese African-American and white American women with pre-diabetes: significance of NMR-derived lipoprotein particle concentrations and sizes

Blood Lipids, Lipoproteins, and Apolipoproteins With Risk of Coronary Heart Disease: A Prospective Study Among Racially Diverse Populations

BACKGROUND

Comprehensive blood lipoprotein profiles and their association with incident coronary heart disease (CHD) among racially and geographically diverse populations remain understudied.

METHODS AND RESULTS

We conducted nested case-control studies of CHD among 3438 individuals (1719 pairs), including 1084 White Americans (542 pairs), 1244 Black Americans (622 pairs), and 1110 Chinese adults (555 pairs). We examined 36 plasma lipids, lipoproteins, and apolipoproteins, measured by nuclear magnetic resonance spectroscopy, with incident CHD among all participants and subgroups by demographics, lifestyle, and metabolic health status using conditional or unconditional logistic regression adjusted for potential confounders. Conventionally measured blood lipids, that is, total cholesterol, triglycerides, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol, were each associated with incident CHD, with odds ratios (ORs) being 1.33, 1.32, 1.24, and 0.79 per 1-SD increase among all participants. Seventeen lipoprotein biomarkers showed numerically stronger associations than conventional lipids, with ORs per 1-SD among all participants ranging from 1.35 to 1.57 and a negative OR of 0.78 (all false discovery rate <0.05), including apolipoprotein B100 to apolipoprotein A1 ratio (OR, 1.57 [95% CI, 1.45-1.7]), low-density lipoprotein-triglycerides (OR, 1.55 [95% CI, 1.43-1.69]), and apolipoprotein B (OR, 1.49 [95% CI, 1.37-1.62]). All these associations were significant and consistent across racial groups and other subgroups defined by age, sex, smoking, obesity, and metabolic health status, including individuals with normal levels of conventionally measured lipids.

CONCLUSIONS

Our study highlighted several lipoprotein biomarkers, including apolipoprotein B/ apolipoprotein A1 ratio, apolipoprotein B, and low-density lipoprotein-triglycerides, strongly and consistently associated with incident CHD. Our results suggest that comprehensive lipoprotein measures may complement the standard lipid panel to inform CHD risk among diverse populations.

The pattern of dyslipidaemia and factors associated with elevated levels of non-HDL-cholesterol among patients with type 2 diabetes mellitus in the Ho municipality: A cross sectional study

Background

Dyslipidaemia is a key comorbid condition of type 2 diabetes mellitus that increases the risk of cardiovascular disease. This study describes the pattern of dyslipidaemia and factors associated with elevated levels of non-high density lipoprotein cholesterol (HDL-C) among patients with type 2 diabetes mellitus in Ho.

Methods

This hospital-based cross-sectional study enrolled 210 patients with type 2 diabetes mellitus from Ho municipality. A semi-structured questionnaire was used to obtain demographic and other relevant parameters. Anthropometric, haemodynamic, and biochemical variables were obtained using standard methods. Dyslipidaemia was defined according to the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) criteria while elevated levels of non-HDL-C was defined as non-HDL-C level ≥3.37 mmol/L. A Chi-square test and multivariate logistic regression analyses were performed to determine factors associated with elevated non-HDL-C levels.

Results

Overall, dyslipidaemia and elevated levels of non-HDL-C prevalence was 67.1% and 64.3%, respectively. The frequency of atherogenic, isolated, and mixed dyslipidaemias were 10.5%, 58.09% and 53.33 %, respectively. Females were four times more likely to develop elevated levels of non-HDL-C after adjustment for age (AOR: 4.07; CI: 2.20-7.51; p < 0.0001). Likewise, overweight (AOR: 3.1; CI: 1.45-6.61; p = 0.0035), grade 1 obesity (AOR: 2.8; CI: 1.20-6.49; p = 0.0168), and truncal obesity (AOR: 3.09; CI: 1.54-6.19; p < 0.0001) were three times each more likely to develop elevated levels of non HDL-C after adjustment for age and gender. However, alcohol intake was 66% unlikely to develop elevated levels of non-HDL-C (COR: 0.34; CI: 0.16-0.73; p = 0.006).

Conclusion

Dyslipidaemia and elevated levels of non-HDL-C were common in our study participants. Hypercholesterolaemia and co-occurrence of high TG and high LDL-C levels were the most prevalent isolated and mixed dyslipidaemias, respectively. The female gender, overweight, grade 1 obesity and truncal obesity, as well as alcohol intake were significant predictors of elevated levels of non-HDL-C.

Lipid traits and type 2 diabetes risk in African ancestry individuals: A Mendelian Randomization study

BACKGROUND

Dyslipidaemia is highly prevalent in individuals with type 2 diabetes mellitus (T2DM). Numerous studies have sought to disentangle the causal relationship between dyslipidaemia and T2DM liability. However, conventional observational studies are vulnerable to confounding. Mendelian Randomization (MR) studies (which address this bias) on lipids and T2DM liability have focused on European ancestry individuals, with none to date having been performed in individuals of African ancestry. We therefore sought to use MR to investigate the causal effect of various lipid traits on T2DM liability in African ancestry individuals.

METHODS

Using univariable and multivariable two-sample MR, we leveraged summary-level data for lipid traits and T2DM liability from the African Partnership for Chronic Disease Research (APCDR) (N = 13,612, 36.9% men) and from African ancestry individuals in the Million Veteran Program (Ncases = 23,305 and Ncontrols = 30,140, 87.2% men), respectively. Genetic instruments were thus selected from the APCDR after which they were clumped to obtain independent instruments. We used a random-effects inverse variance weighted method in our primary analysis, complementing this with additional sensitivity analyses robust to the presence of pleiotropy.

FINDINGS

Increased genetically proxied low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels were associated with increased T2DM liability in African ancestry individuals (odds ratio (OR) [95% confidence interval, P-value] per standard deviation (SD) increase in LDL-C = 1.052 [1.000 to 1.106, P = 0.046] and per SD increase in TC = 1.089 [1.014 to 1.170, P = 0.019]). Conversely, increased genetically proxied high-density lipoprotein cholesterol (HDL-C) was associated with reduced T2DM liability (OR per SD increase in HDL-C = 0.915 [0.843 to 0.993, P = 0.033]). The OR on T2DM per SD increase in genetically proxied triglyceride (TG) levels was 0.884 [0.773 to 1.011, P = 0.072] . With respect to lipid-lowering drug targets, we found that genetically proxied 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) inhibition was associated with increased T2DM liability (OR per SD decrease in genetically proxied LDL-C = 1.68 [1.03-2.72, P = 0.04]) but we did not find evidence of a relationship between genetically proxied proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition and T2DM liability.

INTERPRETATION

Consistent with MR findings in Europeans, HDL-C exerts a protective effect on T2DM liability and HMGCR inhibition increases T2DM liability in African ancestry individuals. However, in contrast to European ancestry individuals, LDL-C may increase T2DM liability in African ancestry individuals. This raises the possibility of ethnic differences in the metabolic effects of dyslipidaemia in T2DM.

FUNDING

See the Acknowledgements section for more information.

Adiponectin is associated with insulin sensitivity in white European men but not black African men

AIMS

We aimed to assess ethnic differences in inflammatory markers and their relationships with insulin sensitivity and regional adiposity between white European and black African men.

METHODS

A total of 53 white European and 53 black African men underwent assessment of inflammatory markers alongside Dixon-magnetic resonance imaging to quantify subcutaneous and visceral adipose tissue and intrahepatic lipid. A hyperinsulinaemic-euglycaemic clamp was used to measure whole-body and adipose tissue insulin sensitivity. To assess ethnic differences in relationships, the statistical significance of an interaction term between adipokines and ethnic group was tested in multivariable regression models.

RESULTS

The black African men exhibited significantly lower adiponectin and tumour necrosis factor-α (TNF-α) and greater interleukin-10 (IL-10) compared to white European men (all p < 0.05). There were no statistically significant ethnic differences in leptin, resistin, IL-6, interferon-γ, IL-13, IL-1β, IL-8 and vascular endothelial growth factor. Several relationships differed significantly by ethnicity such that they were stronger in white European than black African men including IL-6 with visceral adipose tissue; adiponectin with subcutaneous adipose tissue; leptin with intrahepatic lipid; adiponectin, IL-6 and TNF-α with whole-body insulin sensitivity and TNF-α with adipose tissue insulin sensitivity (all pinteraction <0.05). Leptin significantly predicted whole-body insulin sensitivity in white European (R²  = 0.51) and black African (R²  = 0.29) men; however, adiponectin was a statistically significant predictor in only white European men (R²  = 0.22).

CONCLUSIONS

While adiponectin is lower in black African men, its insulin sensitising effects may be greater in white men suggesting that the role of adipokines in the development of type 2 diabetes may differ by ethnicity.

Prevalence and Correlates of Cardio-Metabolic Risk Factors Among Regular Street Food Consumers in Dar es Salaam, Tanzania

BACKGROUND

Regular street food consumers (RSFCs) in Africa are at an increased risk of unhealthy eating practices, which have been associated with intermediate risk factors of cardio-metabolic diseases. However, knowledge of the magnitude and correlates of these risk factors is limited in Tanzania. This study aimed to fill this gap using data collected from RSFCs in Dar es Salaam, the largest city in Tanzania.

METHODOLOGY

A cross-sectional study was carried out among 560 RSFCs in three districts of Dar es Salaam between July and September 2018. Information on socio-economic factors and demographics, behavioral risks, anthropometric and biochemical indicators was collected. Adjusted odds ratios (OR) and prevalence ratio (PR) with corresponding 95% confidence intervals (CI) were estimated using multivariable binary logistic and modified Poisson regression models, respectively.

RESULTS

On average, participants consumed 11 street food meals/week. The prevalence (95% CI) of cardio-metabolic risk factors was 63.9% (60.6-69.9%) for overweight/obesity, 42.5% (38.3-46.9%) for raised blood pressure, 13.5% (10.9-16.8%) for raised triglycerides and 6.6% (4.9-9.3%) for raised glucose levels. The correlates of overweight/obesity were female vs male sex (APR=1.3; 95% CI 1.2-1.5), age of 41-64 vs 25-40 years (APR=1.4; 95% CI 1.2-1.6), high vs low income (APR=1.2; 95% CI 1.04-1.3), being married/cohabiting vs other (APR=1.2; 95% CI 1.01-1.4) and family history of diabetes vs no family history (APR=1.2; 95% CI 1.01-1.3). Age 41-64 vs 25-40 years, was the only significant factor associated with raised blood pressure APR (95% CI) 2.2 (1.7-2.9) and raised glucose AOR (95% CI) 3.9 (1.5-10.5).

CONCLUSION

Our study revealed that RSFCs are at risk of cardio-metabolic health problems, especially women, middle-aged people and those with higher incomes. Transdisciplinary studies to understand the drivers of street food consumption are needed in order to inform interventions to mitigate the risk of developing cardio-metabolic diseases. These interventions should target both street food vendors and their consumers.

Lipoprotein(a) and Cardiovascular Disease Prevention across Diverse Populations

Lipoprotein(a) (Lp(a)) is a highly proatherogenic lipid fraction that is genetically determined and minimally responsive to lifestyle or behavior changes. Mendelian randomization studies have suggested a causal link between elevated Lp(a) and heart disease, stroke, and aortic stenosis. There is substantial inter-ethnic variation in Lp(a) levels, with persons of African descent having the highest median values. Monitoring of Lp(a) has historically been limited by lack of standardization of assays. With the advent of novel therapeutic modalities to lower Lp(a) levels including proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitors and targeted antisense oligonucleotides, it is increasingly important to screen patients who have family or personal history of atherosclerotic cardiovascular disease for elevations in Lp(a). Further study is needed to establish a causal relationship between elevated Lp(a) and cardiovascular disease across diverse ethnic populations.

Circulating amino acids and the risk of macrovascular, microvascular and mortality outcomes in individuals with type 2 diabetes: results from the ADVANCE trial

AIMS/HYPOTHESES

We aimed to quantify the association of individual circulating amino acids with macrovascular disease, microvascular disease and all-cause mortality in individuals with type 2 diabetes.

METHODS

We performed a case-cohort study (N = 3587), including 655 macrovascular events, 342 microvascular events (new or worsening nephropathy or retinopathy) and 632 all-cause mortality events during follow-up, in a secondary analysis of the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) study. For this study, phenylalanine, isoleucine, glutamine, leucine, alanine, tyrosine, histidine and valine were measured in stored plasma samples by proton NMR metabolomics. Hazard ratios were modelled per SD increase in each amino acid.

RESULTS

In models investigating associations and potential mechanisms, after adjusting for age, sex and randomised treatment, phenylalanine was positively, and histidine inversely, associated with macrovascular disease risk. These associations were attenuated to the null on further adjustment for extended classical risk factors (including eGFR and urinary albumin/creatinine ratio). After adjustment for extended classical risk factors, higher tyrosine and alanine levels were associated with decreased risk of microvascular disease (HR 0.78; 95% CI 0.67, 0.91 and HR 0.86; 95% CI 0.76, 0.98, respectively). Higher leucine (HR 0.79; 95% CI 0.69, 0.90), histidine (HR 0.89; 95% CI 0.81, 0.99) and valine (HR 0.79; 95% CI 0.70, 0.88) levels were associated with lower risk of mortality. Investigating the predictive ability of amino acids, addition of all amino acids to a risk score modestly improved classification of participants for macrovascular (continuous net reclassification index [NRI] +35.5%, p < 0.001) and microvascular events (continuous NRI +14.4%, p = 0.012).

CONCLUSIONS/INTERPRETATION

We report distinct associations between circulating amino acids and risk of different major complications of diabetes. Low tyrosine appears to be a marker of microvascular risk in individuals with type 2 diabetes independently of fundamental markers of kidney function.

The Metabolic Syndrome and Its Components in African-American Women: Emerging Trends and Implications

The Metabolic Syndrome (MetS) is recognized as a predictor of cardiovascular outcomes and type 2 diabetes (T2DM). The MetS is a constellation of clinical and metabolic risk factors that include abdominal obesity, dyslipidemia, glucose intolerance, and hypertension. There are ethnic and racial differences in the prevalence of MetS and its components. In general, African-Americans have lower prevalence of MetS when compared to whites, but suffer disproportionately from higher cardiovascular mortality and T2DM. Specifically, African-American women (AAW) have higher rates of T2DM and cardiovascular mortality despite a more favorable lipid and lipoprotein profile. This is paradoxical. However, there is a general upward trend in the prevalence of MetS in the US. The reasons are debatable, but could be multifactorial, including genetics and environmental factors. Thus, there is a need to understand the increasing trend in the MetS, its components, and the associated outcomes for AAW. Therefore, the purpose of this mini review is to (1) understand the increasing prevalence of MetS and its components in AAW and (2) provide suggestions for future prevention of cardiovascular disease and T2DM in AAW.

Lipoprotein-Cholesterol Fractions in Marginalized Roma versus Majority Population

The trend of modern clinical biochemistry is to emphasize the composition and the quality of lipoproteins over their quantity. The serum lipoprotein fractions and subfractions were analyzed by the Lipoprint Lipoprotein Subfractions Testing System, the parameters of lipid profile, as total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C) and triacylglycerides (TAG) were determined by an automated selective biochemical analyzer. Our results showed a significantly lower concentration of cholesterol in the LDL fractions 1 and 2 and in the HDL fractions 8 to 10 in Roma compared to the majority population. The most significant differences between Roma and the majority population when considering body mass index (BMI), waist-to-hip ratio and the index of central obesity were in very low-density lipoproteins (VLDL), intermediate-density lipoproteins, fraction A (IDL-A) and LDL-2. The last two listed were significantly higher in the majority population. VLDL was significantly higher in overweight or obese Roma men and in Roma men with central obesity compared to men from the majority population, as well as in Roma women with normal weight and physiological waist-to-hip ratio compared to the women from majority population. Our study is among the first describing the distribution of lipoprotein subfractions in different ethnic groups.

Disparities in Cardiovascular Disease and Type 2 Diabetes Risk Factors in Blacks and Whites: Dissecting Racial Paradox of Metabolic Syndrome

Cardiovascular diseases (CVD) remain as the leading cause of mortality in the western world and have become a major health threat for developing countries. There are several risk factors that account for the CVD and the associated mortality. These include genetics, type 2 diabetes (T2DM), obesity, physical inactivity, hypertension, and abnormal lipids and lipoproteins. The constellation of these risk factors has been termed metabolic syndrome (MetS). MetS varies among racial and ethnic populations. Thus, race and ethnicity account for some of the differences in the MetS and the associated CVD and T2DM. Furthermore, the relationships among traditional metabolic parameters and CVD differ, especially when comparing Black and White populations. In this regard, the greater CVD in Blacks than Whites have been partly attributed to other non-traditional CVD risk factors, such as subclinical inflammation (C-reactive protein), homocysteine, increased low-density lipoprotein oxidation, lipoprotein a, adiponectin, and plasminogen activator inhibitor-1, etc. Thus, to understand CVD and T2DM differences in Blacks and Whites with MetS, it is essential to explore the contributions of both traditional and non-traditional CVD and T2DM risk factors in Blacks of African ancestry and Whites of Europoid ancestry. Therefore, in this mini review, we propose that non-traditional risk factors should be integrated in defining MetS as a predictor of CVD and T2DM in Blacks in the African diaspora in future studies.