Postprandial apolipoprotein B48 is associated with asymptomatic peripheral arterial disease: a study in patients with type 2 diabetes and controls

Subclinical atherosclerosis burden in non-diabetic hypertensives treated in primary care center: the IMTABI study

BACKGROUND

Identifying patients at high risk of cardiovascular disease in primary prevention is a challenging task. This study aimed at detecting subclinical atherosclerosis burden in non-diabetic hypertensive patients in a primary care centre.

METHODS

Clinical, anthropometric and analytical data were collected from patients with hypertension who were free from clinical vascular disease and diabetes. The cardiovascular risk was assessed using the SCORE system. Subclinical atherosclerosis burden was assessed by carotid ultrasonography (intima-medial thickness [IMT] and plaque) and measurement of the ankle-brachial index (ABI).

RESULTS

Out of 140 patients, 59 (42%) have carotid plaque, 32 (23%) have IMT higher than 75% and 12 (9%) have an ABI < 0.9. Total atherosclerosis burden was present in 91 (65%) of the subjects. Consequently, 59 (42%) patients were re-classified into the very high-risk category. In multivariate analyses, smoking, creatinine levels and duration of hypertension were associated with atherosclerosis burden. In contrast, only smoking and age were associated with the presence of carotid plaque. Almost 90% of patients were treated with hypotensive drugs, half of them combined several drugs and 60% were well-controlled. Only 30% received statins in monotherapy and only less than 20% had an LDL cholesterol < 100 mg/dL.

CONCLUSIONS

In non-diabetic hypertensive patients managed at a primary care centre, 4 out of 10 had subclinical atherosclerosis burden and were re-classified into the very high- risk category. There was clear undertreatment with lipid-lowering drugs of most LDL cholesterol inappropriate levels, according to current clinical guidelines.

Postprandial Hyperlipidemia: Association with Inflammation and Subclinical Atherosclerosis in Patients with Rheumatoid Arthritis

OBJECTIVE

To describe postprandial lipidemia in patients with rheumatoid arthritis (RA) and to analyze its association with subclinical atherosclerosis and inflammatory activity.

METHODS

Observational study of 80 cases of RA and 80 sex- and age-matched controls. We excluded individuals with dyslipidemia. Postprandial hyperlipidemia (PPHL) was defined as postprandial triglycerides >220 mg/dL and/or postprandial ApoB48 levels >75th percentile (>p75). Plasma lipids, cholesterol, triglycerides, ApoB48, and total ApoB were evaluated at baseline and after a meal. Other variables analyzed included subclinical atherosclerosis (defined as presence of carotid atheromatous plaque), inflammatory activity (disease activity score (DAS28-ESR)), cytokines, apolipoproteins, and physical activity. A multivariate analysis was performed to identify factors associated with PPHL in patients with RA.

RESULTS

A total of 75 patients with RA and 67 healthy controls fulfilled the inclusion criteria. PPHL was more frequent in patients with RA than controls (No. (%), 29 (38.70) vs. 15 (22.40); p = 0.036), as was subclinical atherosclerosis (No. (%), 22 (30.10) vs. 10 (14.90); p = 0.032). PPHL in patients with RA was associated with subclinical atherosclerosis (OR (95% CI) 4.69 (1.09-12.11); p = 0.037), TNF-α (OR (95% CI) 2.00 (1.00-3.98); p = 0.048), high-sensitivity C-reactive protein (OR (95% CI) 1.10 (1.01-1.19); p = 0.027), and baseline triglycerides (OR (95% CI) 1.02 (1.00-1.04); p = 0.049).

CONCLUSION

PPHL was more frequent in patients with RA than in controls. PPHL in patients with RA was associated with inflammation and subclinical atherosclerosis.

Association of apolipoprotein levels with peripheral arterial disease: a meta-analysis of literature studies

AIMS

Lower limb peripheral artery disease (PAD) is a leading cause of atherosclerotic cardiovascular disease (ASCVD). Discordant data are available on the association between apolipoprotein and PAD. We performed a meta-analyses on the association between apolipoprotein (apo)B, apoA-I, and apoB/apoA-I ratio with PAD.

METHODS AND RESULTS

PubMed, Web of Science, Scopus databases were systematically searched. Studies providing data about apoB, apoA-I, apoB/apoA-I ratio in PAD subjects and non-PAD controls were included. Differences between PAD and non-PAD subjects were expressed as mean difference (MD) with pertinent 95% confidence intervals (95%CI). Twenty-two studies were included. Peripheral artery disease subjects showed higher apoB (MD: 12.5 mg/dL, 95%CI: 2.14, 22.87) and lower apoA-I levels (MD: -7.11 mg/dL, 95%CI: -11.94, -2.28) than non-PAD controls. Accordingly, ApoB/ApoA-I ratio resulted higher in PAD subjects than non-PAD controls (MD: 0.11, 95% CI: 0.00, 0.21). Non-HDL-C showed a direct association with the difference in apoB (z-value: 4.72, P < 0.001) and an inverse association with the difference of apoA-I (z-value: -2.43, P = 0.015) between PAD subjects and non-PAD controls. An increasing BMI was associated with an increasing difference in apoA-I values between PAD subjects and non-PAD controls (z-value: 1.98, P = 0.047).

CONCLUSIONS

Our meta-analysis suggests that PAD subjects exhibit increased apoB and reduced apoA-I levels, accompanied by an increased apoB/apoA-I ratio as compared with non-PAD controls.

Postprandial Apolipoprotein B48 is Associated with Subclinical Atherosclerosis in Patients with Rheumatoid Arthritis

Objective: To describe postprandial lipemia in patients with rheumatoid arthritis (RA) and to analyze its association with subclinical atherosclerosis measured as carotid intima-media thickness (cIMT). Methods: We performed an observational study of 40 patients with RA and 40 sex and age-matched controls. Patients with dyslipidemia were excluded. Pathologically increased cIMT was defined as a carotid thickness greater than the 90th percentile (>p90) for age and sex. Fasting and postprandial plasma lipids, cholesterol, triglycerides, apolipoprotein B48 (ApoB48), and total ApoB were evaluated. The other variables included were clinical and laboratory values, Framingham score, and the 28-joint Disease Activity Score (DAS28). Two multivariate models were constructed to identify factors associated with pathologic cIMT in patients with RA. Results: Fasting lipid values were similar in patients with RA and controls, although those of postprandial ApoB48 were higher (median (IQR), 14.4 (10.8–12.1) vs. 12.1 (2.3–9,8); p = 0.042). Pathologic cIMT was recorded in 10 patients with RA (25%) and nine controls (22.5%). In patients with RA, pathologic cIMT was associated with postprandial ApoB48 (OR (95% CI), 1.15 (1.0–1.3)) and total ApoB (OR [95% CI], 1.12 [1.1–1.2]). The second model revealed a mean increase of 0.256 mm for cIMT in patients with elevated anticitrullinated protein antibodies (ACPAs). Conclusion: Postprandial ApoB48 levels in patients with RA are higher than in controls. Postprandial ApoB48 and total ApoB levels and markers of severity, such as ACPAs, are associated with pathologic cIMT in patients with RA. Our findings could indicate that these atherogenic particles have a negative effect on the endothelium.

Postprandial Hypertriglyceridaemia Revisited in the Era of Non-Fasting Lipid Profile Testing: A 2019 Expert Panel Statement, Main Text

Residual vascular risk exists despite the aggressive lowering of Low-Density Lipoprotein Cholesterol (LDL-C). A contributor to this residual risk may be elevated fasting, or non-fasting, levels of Triglyceride (TG)-rich lipoproteins. Therefore, there is a need to establish whethe a standardised Oral Fat Tolerance Test (OFTT) can improve atherosclerotic Cardiovascular (CV) Disease (ASCVD) risk prediction in addition to a fasting or non-fasting lipid profile. An expert panel considered the role of postprandial hypertriglyceridaemia (as represented by an OFTT) in predicting ASCVD. The panel updated its 2011 statement by considering new studies and various patient categories. The recommendations are based on expert opinion since no strict endpoint trials have been performed. Individuals with fasting TG concentration <1 mmol/L (89 mg/dL) commonly do not have an abnormal response to an OFTT. In contrast, those with fasting TG concentration ≥2 mmol/L (175 mg/dL) or nonfasting ≥2.3 mmol/L (200 mg/dL) will usually have an abnormal response. We recommend considering postprandial hypertriglyceridaemia testing when fasting TG concentrations and non-fasting TG concentrations are 1-2 mmol/L (89-175 mg/dL) and 1.3-2.3 mmol/L (115-200 mg/dL), respectively as an additional investigation for metabolic risk prediction along with other risk factors (obesity, current tobacco abuse, metabolic syndrome, hypertension, and diabetes mellitus). The panel proposes that an abnormal TG response to an OFTT (consisting of 75 g fat, 25 g carbohydrate and 10 g proteins) is >2.5 mmol/L (220 mg/dL). Postprandial hypertriglyceridaemia is an emerging factor that may contribute to residual CV risk. This possibility requires further research. A standardised OFTT will allow comparisons between investigational studies. We acknowledge that the OFTT will be mainly used for research to further clarify the role of TG in relation to CV risk. For routine practice, there is a considerable support for the use of a single non-fasting sample.

Subclinical Arteriosclerosis is Associated With Common Vascular Risk Factors in Long-Term Survivors of Testicular Cancer

Cardiovascular disease risk is increased in survivors of testicular cancer because of exposure to treatment (chemotherapy and radiotherapy), as well as modification in lifestyle. Our aim was to assess the presence of subclinical arteriosclerosis in survivors of testicular cancer in comparison with a control group. This was a cross-sectional, observational, case–control study including 50 survivors of Germ Cell Tumor (GCT) (14 years of follow-up) and 53 age-matched controls with no cancer. We registered clinical data, cardiovascular risk factors, physical and Mediterranean questionnaires, intima-media thickness and plaque at carotid and femoral arteries by ultrasound, calcium score at the abdominal aorta, and liver steatosis by computed tomography, and applied analytical tests to quantify metabolic risk factors and inflammation markers. Patients showed a trend toward greater intima-media thickness (IMT) and plaques than controls, as well as a higher calcium score in the abdominal aorta. Remarkably, patients had higher waist circumference, insulin resistance (HOMA-IR), and liver steatosis, but lower physical activity and high-density lipoprotein (HDL) cholesterol than controls (all p < 0.05). In multivariate analyses, only common vascular risk factors were associated with subclinical arteriosclerosis. As a conclusion, in our study, a higher rate of subclinical arteriosclerosis in testicular cancer survivors was associated with classical metabolic risk factors and lifestyle, but not with exposure to chemotherapy.

Healthy Effects of Plant Polyphenols: Molecular Mechanisms

The increasing extension in life expectancy of human beings in developed countries is accompanied by a progressively greater rate of degenerative diseases associated with lifestyle and aging, most of which are still waiting for effective, not merely symptomatic, therapies. Accordingly, at present, the recommendations aimed at reducing the prevalence of these conditions in the population are limited to a safer lifestyle including physical/mental exercise, a reduced caloric intake, and a proper diet in a convivial environment. The claimed health benefits of the Mediterranean and Asian diets have been confirmed in many clinical trials and epidemiological surveys. These diets are characterized by several features, including low meat consumption, the intake of oils instead of fats as lipid sources, moderate amounts of red wine, and significant amounts of fresh fruit and vegetables. In particular, the latter have attracted popular and scientific attention for their content, though in reduced amounts, of a number of molecules increasingly investigated for their healthy properties. Among the latter, plant polyphenols have raised remarkable interest in the scientific community; in fact, several clinical trials have confirmed that many health benefits of the Mediterranean/Asian diets can be traced back to the presence of significant amounts of these molecules, even though, in some cases, contradictory results have been reported, which highlights the need for further investigation. In light of the results of these trials, recent research has sought to provide information on the biochemical, molecular, epigenetic, and cell biology modifications by plant polyphenols in cell, organismal, animal, and human models of cancer, metabolic, and neurodegenerative pathologies, notably Alzheimer's and Parkinson disease. The findings reported in the last decade are starting to help to decipher the complex relations between plant polyphenols and cell homeostatic systems including metabolic and redox equilibrium, proteostasis, and the inflammatory response, establishing an increasingly solid molecular basis for the healthy effects of these molecules. Taken together, the data currently available, though still incomplete, are providing a rationale for the possible use of natural polyphenols, or their molecular scaffolds, as nutraceuticals to contrast aging and to combat many associated pathologies.

Gut-derived lipopolysaccharides increase post-prandial oxidative stress via Nox2 activation in patients with impaired fasting glucose tolerance: effect of extra-virgin olive oil

PURPOSE

Post-prandial phase is characterized by enhanced oxidative stress but the underlying mechanism is unclear. We investigated if gut-derived lipopolysaccharide (LPS) is implicated in this phenomenon and the effect of extra virgin olive oil (EVOO) in patients with impaired fasting glucose (IFG).

METHODS

This is a randomized cross-over interventional study including 30 IFG patients, to receive a lunch with or without 10 g of EVOO. Serum LPS, Apo-B48, markers of oxidative stress such as oxidized LDL (oxLDL) and soluble Nox2-derived peptide (sNox2-dp), a marker of nicotinamide-adenine-dinucleotide-phosphate oxidase isoform Nox2 activation, and plasma polyphenols were determined before, 60 and 120 min after lunch.

RESULTS

In patients not given EVOO oxidative stress as assessed by sNox2-dp and oxLDL significantly increased at 60 and 120 min concomitantly with an increase of LPS and Apo-B48. In these patients, changes of LPS were correlated with Apo-B48 (Rs = 0.542, p = 0.002) and oxLDL (Rs = 0.463, p = 0.010). At 120 min, LPS (β - 15.73, p < 0.001), Apo-B48 (β - 0.14, p = 0.004), sNox2-dp (β - 5.47, p = 0.030), and oxLDL (β - 42.80, p < 0.001) significantly differed between the two treatment groups. An inverse correlation was detected between polyphenols and oxLDL (R - 0.474, p < 0.005). In vitro study showed that LPS, at the same concentrations found in the human circulation, up-regulated Nox2-derived oxidative stress via interaction with Toll-like receptor 4.

CONCLUSIONS

Post-prandial phase is characterized by an oxidative stress-related inflammation potentially triggered by LPS, a phenomenon mitigated by EVOO administration.

Evidence for increased chylomicron remnants in rheumatoid arthritis

BACKGROUND

Levels of apolipoprotein (apo) B48 may be increased in conditions associated with systemic inflammation and increased cardiovascular disease (CVD) risk such as rheumatoid arthritis (RA). We aimed to evaluate apo B48 levels in patients with RA in relation to subclinical atherosclerosis.

METHODS

Patients with RA (without CVD) and controls without RA but with high CVD risk (based on the presence of diabetes mellitus or a history of CVD) and healthy controls were included in this cross-sectional study. Carotid intima-media thickness (cIMT) was measured as a surrogate for vascular damage.

RESULTS

In total, 312 patients with RA, 65 controls with high CVD risk and 36 healthy controls were included. Patients with RA had the highest mean apo B48 (10.00 ± 6.65 mg/L) compared to controls with high CVD risk and healthy controls (8.37 ± 5.16 and 5.22 ± 2.46, P < .001). Triglycerides levels were comparable with controls. In RA, apo B48 correlated positively with triglycerides (r = .645; P < .001) but not with cIMT. However, in RA subjects not using lipid or blood pressure lowering medication, a weak correlation was found with cIMT (r = .157; P = .014). RA patients in the highest apo B48 tertile were more often rheumatoid factor positive and anti-CCP positive compared to the lowest tertile.

CONCLUSION

Rheumatoid arthritis patients have higher levels of apo B48 compared to controls with high CVD risk and healthy controls, with normal levels of triglycerides. This accumulation of atherogenic chylomicron remnants may contribute to the elevated CVD risk in RA patients.

Chylomicrons: Advances in biology, pathology, laboratory testing, and therapeutics

The adequate absorption of lipids is essential for all mammalian species due to their inability to synthesize some essential fatty acids and fat-soluble vitamins. Chylomicrons (CMs) are large, triglyceride-rich lipoproteins that are produced in intestinal enterocytes in response to fat ingestion, which function to transport the ingested lipids to different tissues. In addition to the contribution of CMs to postprandial lipemia, their remnants, the degradation products following lipolysis by lipoprotein lipase, are linked to cardiovascular disease. In this review, we will focus on the structure-function and metabolism of CMs. Second, we will analyze the impact of gene defects reported to affect CM metabolism and, also, the role of CMs in other pathologies, such as atherothrombotic cardiovascular disease and diabetes mellitus. Third, we will provide an overview of the laboratory tests currently used to study CM disorders, and, finally, we will highlight current treatments in diseases affecting CMs.

Combined potentiating action of phytochemical(s) from Cinnamomum tamala and Aloe vera for their anti-diabetic and insulinomimetic effect using in vivo rat and in vitro NIH/3T3 cell culture system

The present investigation was undertaken to analyze the ethanolic extracts of leaves of Cinnamomum tamala and Aloe vera for their anti-diabetic and insulinomimitic effect by determining the levels of blood sugar, glycosylated hemoglobin, and serum lipid profile (total cholesterol, triglycerides, high density lipoprotein (HDL), and low density lipoprotein (LDL)) after daily administration of each alone and in combined at 250 mg/kg in alloxan (ALX)-induced diabetic rats. Treatment of diabetic rats with the extracts restored the elevated biochemical parameters significantly. The anti-diabetic effect further potentiated the insulin signaling pathway by co-administration of both extracts. The molecular mechanisms of modulating gene expression and cellular signaling through the insulin receptor were also evaluated on specific targets of the insulin signaling pathway, including insulin receptor substrate (IRS), phosphatidylinositol 3-kinase (PI3-K), AKT, and the glucose transporter (GLUT4) on NIH/3T3 cell line by western blotting, ELISA, semiquantitative RT-PCR, and real-time PCR. The active principle of both extracts revealed insulin mimicking effect as indicated by increased expression of pIRS1 and pAKT in time-dependent manner. There was no significant difference in PI3-K content between unchallenged and challenged groups. Enhanced expression of GLUT-4 transcript further suggested that the Cinnamomum and Aloe phytochemicals could serve as a good adjuvant in the present armamentarium of anti-diabetic drugs by either mimicking or improving insulin action. This study reveals that ethanolic extracts of C. tamala and A. vera have potent therapeutic efficacy and prospect for the development of phytomedicine for diabetes mellitus.

Peripheral arterial disease, type 2 diabetes and postprandial lipidaemia: Is there a link?

Peripheral arterial disease, manifested as intermittent claudication or critical ischaemia, or identified by an ankle/brachial index < 0.9, is present in at least one in every four patients with type 2 diabetes mellitus. Several reasons exist for peripheral arterial disease in diabetes. In addition to hyperglycaemia, smoking and hypertension, the dyslipidaemia that accompanies type 2 diabetes and is characterised by increased triglyceride levels and reduced high-density lipoprotein cholesterol concentrations also seems to contribute to this association. Recent years have witnessed an increased interest in postprandial lipidaemia, as a result of various prospective studies showing that non-fasting triglycerides predict the onset of arteriosclerotic cardiovascular disease better than fasting measurements do. Additionally, the use of certain specific postprandial particle markers, such as apolipoprotein B-48, makes it easier and more simple to approach the postprandial phenomenon. Despite this, only a few studies have evaluated the role of postprandial triglycerides in the development of peripheral arterial disease and type 2 diabetes. The purpose of this review is to examine the epidemiology and risk factors of peripheral arterial disease in type 2 diabetes, focusing on the role of postprandial triglycerides and particles.

[Preliminary analysis of the relationship between peripheral arterial disease and other atherosclerosis markers and diabetic nephropathy]

OBJECTIVES

To determine lipid serum levels, lipoproteins and other markers related to nephropathy and peripheral arterial disease (PAD) in a type 2 diabetes population stratified according to their level of renal dysfunction.

METHODS

A cross-sectional study was conducted on 72 type 2 diabetic patients followed-up in outpatient clinics. Patients were divided into 4 groups according to their estimated glomerular filtration rate (eGFR, mL/min) and albumin/creatinine ratio (ACR, mg/g) (eGFR > 60 and ACR < 30 [n = 23], eGFR > 60 and ACR > 30 [n = 12], eGFR30-60 [n = 23] and eGFR < 30 [n = 14]). Clinical and anthropometric characteristic of all patients were recorded. Fasting lipids and apolipoproteins, as well as renal and hematology parameters were measured. Finally, a multivariate Wald stepwise logistic regression statistic analysis was performed to determine variables independently associated with the presence of renal dysfunction.

RESULTS

The univariate statistical analysis showed that the higher renal dysfunction, the higher the prevalence of hypertension, smoking habit and triglycerides levels, and the lower hemoglobin levels (P < .05). The multivariate statistical analysis showed that only triglycerides levels (OR: 1.019, 95% CI: 1.004-1.034) and hemoglobin levels (OR: 0.516 95% CI: 0.292-0.914) were independently associated to the presence of renal dysfunction (eGFR < 60 mL/min.). The further inclusion of the presence of PAD in the statistical model did not modify those associations.

CONCLUSION

The results confirm the relationship between triglycerides levels and diabetic nephropathy, independently of the presence of PAD.

Postprandial lipaemia and vascular disease

PURPOSE OF REVIEW

In this review we discuss the postprandial pathophysiological mechanisms that promote vascular disease, the evidence for a role of postprandial lipaemia (PPL) in vascular disease and the effect of modifiable and nonmodifiable factors in PPL.

RECENT FINDINGS

PPL refers to the dynamic changes in serum lipids and lipoproteins (mainly in serum triglycerides) that occur after a fat load or a meal. Recent data indicate that postprandial or nonfasting triglyceride levels are better predictors of cardiovascular risk, suggesting that efficiency of postprandial handling of triglyceride-rich lipoproteins plays a role in the causation of vascular disease.

SUMMARY

The recent finding that postprandial serum triglyceride levels are even better than fasting serum triglyceride levels as predictors of vascular disease indicate that it is better to measure an index of triglyceride-rich lipoproteins (in most cases serum triglyceride levels) in the postprandial period than in the postabsorptive fasting state. Moreover, by the time the postabsorptive state is reached, some of these proatherogenic triglyceride-rich lipoprotein changes may be missed in the measurement.

Fasting apolipoprotein B48 is a marker for peripheral arterial disease in type 2 diabetes

An earlier study showed that fasting and postprandial concentrations of apolipoprotein B48 were raised in patients with type 2 diabetes (DM2) and peripheral arterial disease (PAD) as compared with persons without DM2 or persons with DM2 but not PAD. The aim of this study was to confirm the association of PAD and B48 in a larger group of patients with DM2 and the relation of B48 with the preheparin lipoprotein lipase (LPL) mass. We studied 456 patients with DM2. PAD was defined as an ankle-brachial index (ABI) <0.9. Apolipoprotein B48 was quantified by ELISA. Apo B48 was significantly higher in the group with an ABI <0.9 than the groups with ABI of 0.9-1.3 and >1.3 (10.7 ± 6.28 vs. 9.24 ± 5.5 vs. 9.17 ± 8.8 mg/L, ANOVA test, p < 0.05). B48 was independently associated with an ABI <0.9 (OR 1.053; 95 % CI, 1.013-1.094; p < 0.05), together with smoking and duration of diabetes. The preheparin LPL mass was similar in the patients with and without PAD. In conclusion, we confirmed that fasting B48 is an independent marker of PAD in patients with DM2, unrelated to the preheparin LPL mass, statin therapy or glucose lowering treatment.

Fasting APO B48 levels are associated with microalbuminuria in patients with type 2 diabetes

In view of the high incidence of macrovascular diseases in patients with type 2 diabetes mellitus and microalbuminuria, the study evaluates the association of microalbuminuria with fasting plasma Apo B48 levels, a marker of the residual presence of intestinally derived TRLs lipoproteins, thought to be highly atherogenic. We studied 50 patients with type 2 diabetes aged 35-75 years. Exclusion criteria were overt macrovascular disease, overt nephropathy (Glomerular filtration rate (GFR) <45 ml/min/1.73 m(2)), or use of hypolipidemic agents. Anthropometry, fasting plasma lipids, plasma creatinine, and HbA1c were measured. Urinary albumin excretion was measured on a morning urine sample with the ELISA and expressed as albumin/creatinine ratio. GFR was estimated using the MDRD formula. The plasma fasting Apo B48 was measured by ELISA. Age, gender distribution, fasting plasma lipids, HbA1c, smoking status, plasma creatinine, estimate GFR, and the proportion of patients treated with insulin or antihypertensive drugs were similar for patients with or without microalbuminuria. People with microalbuminuria had longer diabetes duration (borderline significance) and significantly higher Apo B48 (1.765 ± 1.379 μg/ml vs. 1.022 ± 0.692 μg/ml, p = 0.01) than those without microalbuminuria. Multivariate logistic regression analysis confirmed that fasting Apo B48 levels were significantly associated with microalbuminuria independent of major confounders measured in the study. In patients with type 2 diabetes, microalbuminuria is associated with elevated Apo B48 levels, independent of major confounders; this may partly explain the excess cardiovascular risk of these patients.

Postprandial dyslipidaemia and diabetes: mechanistic and therapeutic aspects

PURPOSE OF REVIEW

There has been a resurgence of interest in the role of triglyceride-rich lipoproteins in the development of atherosclerosis and cardiovascular disease, and this is particularly relevant to diabetes mellitus and the postprandial state.

RECENT FINDINGS

Recent evidence suggests that insulin resistance in diabetes induces postprandial dyslipidemia by increasing the enterocytic production of chylomicrons and their remnant particles, but an impaired clearance capacity is also involved. Postprandial dyslipidaemia in diabetes induces oxidative stress, inflammation and endothelial dysfunction and this may be compounded by dysglycaemia. New guidelines for managing hypertriglyceridaemia in diabetes have been published, first-line therapies being improved glycaemic control, treatment of other secondary causes of dyslipidaemia and statin therapy, followed by judicious use of fibrates, n-3 fatty acids or niacin. A new role for incretin-based therapies in regulating dyslipidaemia has been identified.

SUMMARY

Postprandial dyslipidaemia is a pivotal mechanism whereby diabetes can induce and accelerate atherosclerosis. Regulating the plasma concentrations of triglyceride-rich lipoproteins may decrease the cardiovascular complications of diabetes. The mechanisms of action of incretin-based treatments on dyslipidaemia and endothelial dysfunction need further investigation. The efficacy of new therapies targeted at postprandial dysmetabolism in diabetes need to be confirmed, against best current levels of care, in clinical endpoint trials.

Exploring the value of apoB48 as a marker for atherosclerosis in clinical practice

BACKGROUND

  Postprandial accumulation of atherogenic remnants has been described in patients with type 2 diabetes mellitus (T2DM), familial combined hyperlipidaemia (FCH), familial hypercholesterolaemia (FH) and coronary artery disease (CAD). Scarce data are available on fasting plasma apolipoprotein (apo) B48 levels in relation to these conditions and atherosclerosis.

DESIGN

  Treated patients with FCH (18), FH (20), T2DM (26), CAD (65), T2DM with CAD (T2DM/CAD) (28) and 33 healthy controls were included. Intima-media thickness (IMT) measurements were carried out to investigate subclinical atherosclerosis.

RESULTS

  LDL-C and total apoB were lowest in patients with T2DM/CAD owing to the more frequent use of lipid-lowering medication. Fasting plasma apoB48 was elevated in patients with FCH (11·38 ± 1·50 mg/L) and T2DM/CAD (9·65 ± 1·14 mg/L) compared with the other groups (anova, P < 0·01). CAD patients (8·09 ± 0·57 mg/L) had higher apoB48 levels than controls (5·74 ± 0·55 mg/L) and FH patients (5·40 ± 0·51 mg/L) (P = 0·02). IMT was highest in subjects with T2DM/CAD (0·77 ± 0·03 mm) (P < 0·01). The lowest IMT was measured in controls (0·56 ± 0·02 mm) and FCH patients (0·60 ± 0·03 mm). In the total group, the best association for apoB48 was found with fasting triglyceride (Pearson's r = 0·72, P < 0·001). In the subjects not using statins (n = 74), the best correlation was found with IMT (r = 0·52; P < 0·001), whereas total apoB was not associated with IMT (r = 0·20, P = 0·12).

CONCLUSIONS

  ApoB48 concentrations are highest in patients with FCH and in atherosclerotic subjects with T2DM. In patients not using statins, the surrogate atherosclerosis marker IMT correlates best with apoB48, suggesting that fasting apoB48 may help to detect subjects at risk.

Fasting apolipoprotein B48 is associated with asymptomatic peripheral arterial disease in type 2 diabetic subjects: a case-control study

OBJECTIVE

To test whether there is an association between fasting ApoB48 level, a marker of the residual presence of intestinally derived TRLs lipoproteins, thought to be highly atherogenic, and peripheral artery disease (PAD) in type 2 diabetic patients independent of fasting plasma lipids.

METHODS

We studied 87 patients with type 2 diabetes: 34 with asymptomatic PAD (ankle/brachial index < 0.9) and 53 without PAD matched on age (±2 years), gender and BMI (±2 kg/m(2)). The plasma fasting ApoB48 was measured by ELISA.

RESULTS

Patients with PAD had significantly higher ApoB48 levels (1.529 ± 1.253 vs 1.095 ± 0.667 μg/ml p = 0.04) than those without PAD independent of major confounders, such as duration of diabetes, smoking status, HbA1c, systolic blood pressure and fasting plasma lipids.

CONCLUSIONS

Fasting ApoB48 was independently associated with asymptomatic PAD in patients with type 2 diabetes.

Apolipoproteins: metabolic role and clinical biochemistry applications

Lipoprotein metabolism is dependent on apolipoproteins, multifunctional proteins that serve as templates for the assembly of lipoprotein particles, maintain their structure and direct their metabolism through binding to membrane receptors and regulation of enzyme activity. The three principal functions of lipoproteins are contribution to interorgan fuel (triglyceride) distribution (by means of the fuel transport pathway), to the maintenance of the extracellular cholesterol pool (by means of the overflow pathway) and reverse cholesterol transport. The most important clinical application of apolipoprotein measurements in the plasma is in the assessment of cardiovascular risk. Concentrations of apolipoprotein B and apolipoprotein AI (and their ratio) seem to be better markers of cardiovascular risk than conventional markers such as total cholesterol and LDL-cholesterol. Apolipoprotein measurements are also better standardized than the conventional tests. We suggest that measurements of apolipoprotein AI and apolipoprotein B are included as a part of the specialist lipid profile. We also suggest that lipoprotein (a) should be measured as part of the initial assessment of dyslipidaemias because of its consistent association with cardiovascular risk. Genotyping of apolipoprotein E isoforms remains useful in the investigation of mixed dyslipidaemias. Lastly, the role of postprandial metabolism is increasingly recognized in the context of atherogenesis, obesity and diabetes. This requires better markers of chylomicrons, very-low-density lipoproteins and remnant particles. Measurements of apolipoprotein B48 and remnant lipoprotein cholesterol are currently the key tests in this emerging field.