Reference distributions for apolipoproteins AI and B and the apolipoprotein B/AI ratios: a practical and clinically relevant approach in a large cohort

Clinical Interest of Serum Alpha-2 Macroglobulin, Apolipoprotein A1, and Haptoglobin in Patients with Non-Alcoholic Fatty Liver Disease, with and without Type 2 Diabetes, before or during COVID-19

In patients with non-alcoholic fatty liver disease (NAFLD) with or without type 2 diabetes mellitus (T2DM), alpha-2 macroglobulin (A2M), apolipoprotein A1 (ApoA1), and haptoglobin are associated with the risk of liver fibrosis, inflammation (NASH), and COVID-19. We assessed if these associations were worsened by T2DM after adjustment by age, sex, obesity, and COVID-19. Three datasets were used: the “Control Population”, which enabled standardization of protein serum levels according to age and sex (N = 27,382); the “NAFLD-Biopsy” cohort for associations with liver features (N = 926); and the USA “NAFLD-Serum” cohort for protein kinetics before and during COVID-19 (N = 421,021). The impact of T2DM was assessed by comparing regression curves adjusted by age, sex, and obesity for the liver features in “NAFLD-Biopsy”, and before and during COVID-19 pandemic peaks in “NAFLD-Serum”. Patients with NAFLD without T2DM, compared with the values of controls, had increased A2M, decreased ApoA1, and increased haptoglobin serum levels. In patients with both NAFLD and T2DM, these significant mean differences were magnified, and even more during the COVID-19 pandemic in comparison with the year 2019 (all p < 0.001), with a maximum ApoA1 decrease of 0.21 g/L in women, and a maximum haptoglobin increase of 0.17 g/L in men. In conclusion, T2DM is associated with abnormal levels of A2M, ApoA1, and haptoglobin independently of NAFLD, age, sex, obesity, and COVID-19.

Serum lipid, lipoprotein and apolipoprotein profiles in workers exposed to low arsenic levels: Lipid profiles and occupational arsenic exposure

Epidemiologic studies have reported that exposure to arsenic (As) is associated with higher risk of cardiovascular disease (i.e., coronary heart disease and peripheral arterial heart disease) and mortality. This cross-sectional study aimed to compare serum lipid, lipoprotein, and apolipoprotein profiles in workers exposed to As. The subjects of this study included 57 workers exposed to As and 57 controls. Demographic characteristics and occupational information were collected through questionnaires. Exposure to As was assessed in indoor air of a workplace and determined using the creatinine values in the urine. Blood samples were collected using immunochemistry and nephelometry to measure the levels of total cholesterol (CHOL), triglycerides (TRIG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), lipoprotein(a) (Lp(a)), apolipoprotein-A1 (Apo-A1), and apolipoprotein-B (Apo-B). No significant difference in the demographic data was detected between the two groups. Urinary As concentration was significantly (p<0.001) higher in exposed subjects than in the controls (13.4±6.1 and 4.4±6.1μg/gCreat, respectively). No statistically significant differences were observed in CHOL, TRIG, HDL, and LDL concentrations between the two groups. Lp(a), Apo-B, and Apo-B/Apo-A1 ratio values were significantly higher and the Apo-A1 level was significantly lower in the exposed group than in the control subjects. Regression analysis highlighted a significant (p<0.001) association between urinary As and Lp(a), Apo-A1, and Apo-B concentration, and Apo-B/Apo-A1 ratio. This study revealed the influence of As on apolipoproteins, suggesting a potential risk of cardiovascular diseases in subjects exposed to low levels of As.

Usefulness of MALDI-TOF/MS identification of low-MW fragments in sera for the differential diagnosis of pancreatic cancer

OBJECTIVES

To identify new biomarkers of pancreatic cancer (PaCa), we performed MALDI-TOF/MS analysis of sera from 22 controls, 51 PaCa, 37 chronic pancreatitis, 24 type II diabetes mellitus (DM), 29 gastric cancer (GC), and 24 chronic gastritis (CG).

METHODS

Sera were purified by Sep-Pak C18 before MALDI-TOF/MS Anchorchip analysis.

RESULTS

Features present in at least 5% of all spectra were selected (n = 160, m/z range, 1200-5000). At univariate analysis, 2 features (m/z 2049 and 2305) correlated with PaCa, 3 (m/z 1449, 1605, and 2006) with DM. No feature characterized gastric cancer or chronic gastritis. Ten-fold cross-validation binary recursive partitioning trees were obtained for patients' classification. The tree (CA 19-9, age, m/z 2006, 2599, 2753, and 4997), built considering only patients with diabetes, allowed a distinction between DM [area under the receiver operating characteristic curve (AUC), 0.997], chronic pancreatitis (AUC, 0.968), and PaCa (AUC, 0.980), with an overall correct classification rate of 89%. The tree including CA 19-9, 1550, and 2937 m/z features, achieved an AUC of 0.970 in distinguishing localized from advanced PaCa. MALDI-TOF-TOF analysis revealed the 1550 feature as a fragment of Apo-A1, which was determined as whole protein and demonstrated to be closely correlated with PaCa.

CONCLUSIONS

The findings made demonstrate a role for serum peptides identified using MALDI-TOF/MS for addressing PaCa diagnosis.

Plasma concentrations of apolipoproteins A-I, B and M in patients with abdominal aortic aneurysms

OBJECTIVES

Apolipoproteins play important roles in the development of atherosclerosis but their involvement in the pathogenesis of abdominal aortic aneurysm (AAA) is poorly understood. The aim was to investigate whether apoA-I, apoB and apoM are independently associated with AAA.

DESIGN AND METHODS

Plasma apoA-I, apoB and apoM were measured in 343 patients with AAA and in 214 elderly apparently healthy control individuals from the background population.

RESULTS

AAA patients had lower apolipoprotein levels, as compared to healthy individuals: apoA-I, 1.62 vs. 2.08 g/L; apoB, 0.91 vs. 1.04 g/L; apoM, 0.72 vs. 0.91 mumol/L (p<0.0001 for all three). In multivariate analyses, apoA-I and apoB were associated with AAA, odds ratios (95% confidence intervals) being 0.53 (0.43-0.64) and 0.86 (0.75-0.998), respectively.

CONCLUSIONS

ApoA-I, apoB and apoM levels were significantly lower in patients with AAA than in the control individuals, but only apoA-I and apoB were independently associated to AAA.

Apo-B/AI ratio identifies cardiovascular risk in childhood: the Australian Aboriginal Birth Cohort study

We describe the lipoprotein and apolipoprotein profiles and their relationship to cardiovascular risk factors in Australian Aboriginal children. This cross-sectional study within a longitudinal birth cohort study involved Australian Aboriginal children born between 1987 and 1990 and re-examined between 1998 and 2001. Height, weight, blood pressure, waist circumference, body fat percentage, cholesterol, triglycerides, HDL-c, LDL-c, apolipoprotein B and A1 were measured. Mean age was 11.4 years (52% male). Mean cholesterol, triglyceride, HDL-c and LDL-c did not differ from reference data. Measures of obesity, blood pressure and prevalence of the metabolic syndrome did not differ in those children with lipoproteins in the upper quartile of the cohort (lower quartile for HDL-c). Boys with an Apo-B/A1 ratio in the upper quartile of the cohort had higher BMI z-score, waist z-score, % body fat, diastolic blood pressure and frequency of the metabolic syndrome (p<0.05). In girls, waist circumference, % body fat and the prevalence of the metabolic syndrome was higher in those with an Apo-B/A1 ratio in the upper quartile (p<0.05).The Apo-B/A1 ratio may be useful to identify cardiovascular risk in Australian Aboriginal children and is suited to clinical practice as the assays are standardised, accurate, automated and a fasting sample is not required.

ApoB/ApoA-I ratio in young patients with ischemic cerebral stroke or peripheral arterial disease

Although smoking and hypertension are classic risk factors for atherothrombotic diseases, the relationship of dyslipidemia and vascular diseases, other than myocardial infarction, is less clearly established, especially in young subjects. In the current study, a detailed analysis of the lipid and apolipoprotein profiles was conducted in young patients of ischemic cerebral stroke (IS) and peripheral arterial disease (PAD). Plasma levels of C-reactive protein (hs-CRP), total cholesterol (TC), high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc), triglycerides (TG), and apolipoproteins A-I (ApoA-I) and apolipoproteins B (ApoB), which include the ApoB/ApoA-I ratio, were analyzed in a group of 81 patients who presented with IS (n = 46) or PAD (n = 35) as well as in 167 control subjects. Significant differences were observed for hs-CRP, TC, HDLc, LDLc, TG, ApoA-I, and ApoB levels, as well as for the ApoB/ApoA-I ratio, between the control and the IS or PAD groups. However, after adjustment for sex, age, smoking, hypertension, hs-CRP, and dyslipidemia (LDLc, TC, HDLc, TG, ApoA, ApoB, and ApoB/ApoA-I ratio), hs-CRP, ApoB, and the ApoB/ApoA-I ratio were independently associated with increased risks of IS or PAD. Increased ApoB/ApoA-I ratio and hs-CRP levels are independently associated with occurrence of IS and PAD in young patients and are significant markers of alterations on lipid and apolipoproteic profiles and inflammatory responses, respectively, in these patients.

Apolipoprotein A-I versus HDL cholesterol in the prediction of risk for myocardial infarction and stroke

PURPOSE OF REVIEW

To compare the potential of high-density lipoprotein (HDL) cholesterol and apolipoprotein (apo) A-I, the major protein in HDL particles, in predicting cardiovascular risk. Pros and cons for using these risk markers are discussed.

RECENT FINDINGS

Both HDL cholesterol and apoA-I are in most clinical conditions antiatherogenic - the higher the values, the lower the cardiovascular risk. Methodological and physiological factors speak in favour of using apoA-I rather than HDL cholesterol as a marker of risk. In prospective risk studies and in lipid-lowering trials it has been shown that the apoB/A-I ratio, which reflects the cholesterol balance between all potentially atherogenic (apoB) and antiatherogenic lipoproteins (apoA-I), is a better risk marker than low-density lipoprotein cholesterol, HDL cholesterol and lipid ratios in predicting cardiovascular risk and response to lipid lowering induced by statins. Practical advantages speak in favour of using apoB and apoA-I - fasting is not needed to analyze and interpret the values of apoB and apoA-I.

SUMMARY

New guidelines should be developed in which target values for apoB and apoA-I are defined to enable the use of these new strong risk markers/factors in clinical practice.

Reference distributions for apolipoproteins AI and B and B/AI ratios: comparison of a large cohort to the world's literature

Limiting the clinical utility of apolipoproteins AI (apo AI) and B (apo B) and the apo B/AI ratios until the last decade has been the lack of satisfactory methods for quantifying serum levels and credible reference materials. Great technological strides have been made in the last few years. The remaining barrier to more relevant and cost-effective use of serum protein data for diagnosis and prognosis has been the availability of widely recognized reliable reference intervals from birth to old age for both males and females. A total of 82 publications reporting reference intervals have been identified that meet most of the same inclusion criteria used in our prior six studies. These have been analyzed statistically and compared to similar studies, i.e., sufficient number, listed subject criteria, method, and reference material, in general terms. Published smaller studies with constrained age ranges, agree on average with our large series of life-long reference intervals that range from less than one year to over 80 years. This study was performed to assess the degree of agreement between smaller reference interval studies to our large population analysis. This meta-analysis provides support and reassurance that many of the smaller reference intervals published previously fall within reasonable limits of out large population.