Associations among smoking status, lifestyle and lipoprotein subclasses

Metabolic profiling of smoking, associations with type 2 diabetes and interaction with genetic susceptibility

BACKGROUND

Smokers are at increased risk of type 2 diabetes (T2D), but the underlying mechanisms are unclear. We investigated if the smoking-T2D association is mediated by alterations in the metabolome and assessed potential interaction with genetic susceptibility to diabetes or insulin resistance.

METHODS

In UK Biobank (n = 93,722), cross-sectional analyses identified 208 metabolites associated with smoking, of which 131 were confirmed in Mendelian Randomization analyses, including glycoprotein acetyls, fatty acids, and lipids. Elastic net regression was applied to create a smoking-related metabolic signature. We estimated hazard ratios (HR) of incident T2D in relation to baseline smoking/metabolic signature and calculated the proportion of the smoking-T2D association mediated by the signature. Additive interaction between the signature and genetic risk scores for T2D (GRS-T2D) and insulin resistance (GRS-IR) on incidence of T2D was assessed as relative excess risk due to interaction (RERI).

FINDINGS

The HR of T2D was 1·73 (95% confidence interval (CI) 1·54 - 1·94) for current versus never smoking, and 38·3% of the excess risk was mediated by the metabolic signature. The metabolic signature and its mediation role were replicated in TwinGene. The metabolic signature was associated with T2D (HR: 1·61, CI 1·46 - 1·77 for values above vs. below median), with evidence of interaction with GRS-T2D (RERI: 0·81, CI: 0·23 - 1·38) and GRS-IR (RERI 0·47, CI: 0·02 - 0·92).

INTERPRETATION

The increased risk of T2D in smokers may be mediated through effects on the metabolome, and the influence of such metabolic alterations on diabetes risk may be amplified in individuals with genetic susceptibility to T2D or insulin resistance.

Healthy lifestyle, plasma metabolites, and risk of cardiovascular disease among individuals with diabetes

BACKGROUND AND AIMS

Lifestyle management is a fundamental aspect of diabetes care to prevent cardiovascular disease (CVD); however, the underlying metabolic mechanism is not well established. We aimed to identify metabolites associated with different lifestyle factors, and estimate their mediating roles between lifestyle and CVD risk among people with diabetes.

METHODS

Lifestyle and metabolomic data were available for 5072 participants with diabetes who were free of CVD at baseline in the UK Biobank. The healthy level of 5 lifestyle factors was defined as non-central obesity, non-current smoking, moderate alcohol intake, physically active, and healthy diet. A total of 44 biomarkers across 7 metabolic pathways including lipoprotein particles, fatty acids, amino acids, fluid balance, inflammation, ketone bodies, and glycolysis were quantified by nuclear magnetic resonance (NMR) spectroscopy.

RESULTS

All 44 assayed metabolites were significantly associated with at least one lifestyle factor. Approximately half of metabolites, which were mostly lipoprotein particles and fatty acids, showed a mediating effect between at least one lifestyle factor and CVD risk. NMR metabolites jointly mediated 43.4%, 30.0%, 16.8%, 43.4%, and 65.5% of the association of non-central obesity, non-current smoking, moderate alcohol intake, physically active, and healthy diet with lower CVD risk, respectively. In general, though metabolites that significantly associated with lifestyle were mostly different across the 5 lifestyle factors, the pattern of association was consistent between fatty acids and all 5 lifestyle factors. Further, fatty acids showed significant mediating effects in the association between all 5 lifestyle factors and CVD risk with mediation proportion ranging from 12.2% to 26.8%.

CONCLUSIONS

There were large-scale differences in circulating NMR metabolites between individuals with diabetes who adhered to a healthy lifestyle and those did not. Differences in metabolites, especial fatty acids, could partially explain the association between adherence to multiple healthy lifestyle and lower CVD risk among people with diabetes.

Prevalence, awareness, treatment and control of dyslipidemia in older persons in urban and rural population in the Astana region, Kazakhstan

BACKGROUND

Despite high cardiovascular mortality in Central Asian republics of the former Soviet Union, there is limited information about major risk factors, including blood lipids. We investigated the prevalence of impaired concentrations of blood lipids, the awareness, treatment and control of hypercholesterolemia, and factors associated with these indicators in urban and rural populations in Kazakhstan.

METHODS

We conducted a cross-sectional study of random urban and rural population samples (the state capital Astana and Akmol village). Men and women aged 50-74 years were examined; a total of 954 adults participated (response rate 59%). Serum concentrations of total, LDL and HDL cholesterol and triglycerides and a range of other cardiovascular risk factors were measured.

RESULTS

The overall prevalence of hypercholesterolemia (total cholesterol ≥6.2 mmol/l) was 37%; among subjects with hypercholesterolemia, 57% were aware of their condition, 41% took medication and 23% had total cholesterol <6.2 mmol/l (4.5% <5 mmol/l). The prevalence, awareness, treatment, and control of hypercholesterolemia were all higher in the urban than the rural area. Similarly, the proportions of subjects with impaired concentrations of specific lipids fractions were also considerably higher in the urban population. Most associations with other covariates were in the expected direction.

CONCLUSIONS

This study found relatively high prevalence of dyslipidemia in the Kazakh population, and the blood lipid profile was less favourable in the urban area. These pronounced urban-rural differences may be related to urbanization, the associated nutrition transition and to access to health care.

Associations between obesity, adverse behavioral patterns and cardiovascular risk factors among adolescent inhabitants of a Greek island

BACKGROUND

Excess weight, unhealthy lifestyle habits and their sequelae have become a well-recognized public health problem in most countries. The objective of the study was to examine the relationship of adolescent overweight/obesity with behavioral habits and their association with blood pressure (BP) and lipid profile.

METHODS

Anthropometric parameters, lifestyle, BP and lipid profile of 736 adolescents were evaluated cross-sectionally. The classifications of normal weight, overweight and obese were based on BMI z-scores.

RESULTS

About 42.1% of adolescents were overweight/obese, 11.3% were smokers, 33.2% consumed alcohol and 34% reported low activity. Males began smoking earlier, consumed alcohol more often, exercised less and spent more screen time than females. Alcohol consumption was more prevalent among smokers and was associated with higher BP and dyslipidemia. Smokers exercised less intensely and had lower high density lipoprotein-cholesterol (HDL-C) than non-smokers. Obesity was a risk factor for higher BP and dyslipidemia. Longer screen time was associated with higher triglycerides, while intense physical activity with lower systolic BP.

CONCLUSIONS

Obesity is related to an adverse lipid and BP profile during adolescence. Clustering of hazardous habits was observed, which is known to aggravate the cardiovascular risk.

Dysfunctional HDL and atherosclerotic cardiovascular disease

High-density lipoproteins (HDLs) protect against atherosclerosis by removing excess cholesterol from macrophages through the ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1) pathways involved in reverse cholesterol transport. Factors that impair the availability of functional apolipoproteins or the activities of ABCA1 and ABCG1 could, therefore, strongly influence atherogenesis. HDL also inhibits lipid oxidation, restores endothelial function, exerts anti-inflammatory and antiapoptotic actions, and exerts anti-inflammatory actions in animal models. Such properties could contribute considerably to the capacity of HDL to inhibit atherosclerosis. Systemic and vascular inflammation has been proposed to convert HDL to a dysfunctional form that has impaired antiatherogenic effects. A loss of anti-inflammatory and antioxidative proteins, perhaps in combination with a gain of proinflammatory proteins, might be another important component in rendering HDL dysfunctional. The proinflammatory enzyme myeloperoxidase induces both oxidative modification and nitrosylation of specific residues on plasma and arterial apolipoprotein A-I to render HDL dysfunctional, which results in impaired ABCA1 macrophage transport, the activation of inflammatory pathways, and an increased risk of coronary artery disease. Understanding the features of dysfunctional HDL or apolipoprotein A-I in clinical practice might lead to new diagnostic and therapeutic approaches to atherosclerosis.

The change in motivating factors influencing commencement, adherence and retention to a supervised resistance training programme in previously sedentary post-menopausal women: a prospective cohort study

Background

Understanding motivators for exercise participation in post-menopausal women may impact retention to exercise programmes and inform intervention trial designs. The purpose of this investigation was to assess self-reported motivational factors influencing adherence and retention to a 24-week progressive resistance training programme.

Methods

Post-menopausal females (n = 34) were passively recruited to undertake a 24-week progressive resistance training protocol, in small-group sessions, on three non-consecutive days of the week. Attendance was recorded by the researcher. Qualitative reports were sourced from the sample for four phases of the study: pre-study (prior to week 1), recruitment (week 1), during study (weeks 2 – 24), and post-intervention (beyond week 24). Responses were categorised according to ten descriptors: specific health index improvement, education, flexibility of time, social contact, conscience (loyalty to the researcher), wellness, weight management, organisation parameters (pertaining to the study programme) and enjoyment of the exercises.

Results

Of the initial sample, 76.5% (n = 26) met the specified ≥80% attendance criterion. The primary findings were that motivation to volunteer for the study was driven by a perceived need for a structured exercise programme (50% of respondents). A commitment to the researcher was the primary motivator for continued adherence to the study for 50% of participants. Social contact with other participants was cited by 60% of the sample as the primary reason for adherence for the full duration of 24 weeks. A desire to maintain the “wellness” derived from the programme was cited by 60% as a reason for continuing an exercise routine post-study.

Conclusion

This study identified that routine and supervision initially attract women to exercise programmes, while social cohesion of the group setting contributes to retention over time. Understanding the changing nature of motivating factors may contribute to better overall adherence and retention to exercise programmes and interventions.

Higher levels of small dense low-density lipoprotein (LDL) are associated with cardiac autonomic neuropathy in patients with type 2 diabetes

AIM

To investigate the relationship between small dense LDL cholesterol and cardiac autonomic neuropathy among patients with Type 2 diabetes.

METHODS

A total of 175 patients who had not taken lipid-lowering agents previously were enrolled consecutively in this study. Small dense LDL cholesterol level was measured using polyacrylamide tube gel electrophoresis, which fractionates LDL cholesterol into seven components according to particle size and charge. We analysed the mean LDL cholesterol particle size and the proportion of small dense LDL cholesterol.

RESULTS

The mean (± sd) patient age was 56 (± 14) years, the mean (± sd) duration of diabetes was 10.3 (± 8.3) years, the mean (± sd) proportion of small dense LDL cholesterol was 21.3 (± 17.6)% and the mean (± sd) LDL cholesterol size was 26.33 (± 0.8) nm. Men with cardiac autonomic neuropathy had a longer duration of diabetes compared with those without cardiac autonomic neuropathy. Women with cardiac autonomic neuropathy had a larger waist circumference, higher plasma triglyceride levels, smaller mean (± sd) LDL cholesterol size [26.8 (± 4.3) nm vs 26.4 (± 6.9) nm; P < 0.01] and larger mean (± sd) proportion of small dense LDL cholesterol [10.1 (± 9.9)% vs 19.1 (± 16.8)%; P < 0.01] compared with those without cardiac autonomic neuropathy. After adjusting for other confounding risk factors, the triglyceride/ HDL cholesterol ratio (odds ratio = 1.698, 95% CI: 1.07-2.69; P = 0.025) and mean LDL cholesterol size (odds ratio = 0.873, 95% CI: 0.77-0.99; P = 0.038) remained as independent risk factors for cardiac autonomic neuropathy in women.

CONCLUSIONS

A more atherogenic lipid profile such as the triglyceride: HDL cholesterol ratio and a smaller mean LDL cholesterol particle size were related to the prevalence of cardiac autonomic neuropathy in women with Type 2 diabetes.

Gender difference in the relationship between passive smoking exposure and HDL-cholesterol levels in late adolescence

BACKGROUND

High-density lipoprotein-cholesterol (HDL-C) levels are influenced by gender and by genetic and environmental factors. We aimed to assess the impact of passive smoking exposure since birth on HDL-C levels of nonsmoking adolescents at age 17 years and to determine whether there was a gender difference in the relationship between smoking exposure and HDL-C.

METHODS

A total of 804 nonsmoking adolescents with biochemical, anthropometric, and lifestyle data from a cohort of 1754 adolescents (mean age, 17 ± 0.25 y) of the Western Australian Pregnancy Cohort (Raine) Study had data of maternal smoking during pregnancy and smoking exposure in the household over 17 years. HDL-C was analyzed using multivariable linear regression, with adjustment for early-life, adiposity, and current lifestyle confounders.

RESULTS

HDL-C levels were significantly lower in girls exposed to passive smoking compared to those not exposed (regression coefficient b = -0.09 [95% confidence interval, -0.15, -0.03]); this was not observed in boys (b = 0.02 [95% confidence interval, -0.04, 0.08]), with a significant sex interaction P = .009. The effects of passive smoking in girls persisted after adjusting for oral contraceptive use.

CONCLUSIONS

This study has shown a gender difference in the relationship between passive smoking exposure since birth and HDL-C in late adolescence. Exposure to passive smoking in girls could have adverse consequences on their risk of cardiovascular disease in adulthood. These findings reinforce the need for future public health measures to reduce children's exposure to passive smoking.