Interferences from blood collection tube components on clinical chemistry assays

Improper design or use of blood collection devices can adversely affect the accuracy of laboratory test results. Vascular access devices, such as catheters and needles, exert shear forces during blood flow, which creates a predisposition to cell lysis. Components from blood collection tubes, such as stoppers, lubricants, surfactants, and separator gels, can leach into specimens and/or adsorb analytes from a specimen; special tube additives may also alter analyte stability. Because of these interactions with blood specimens, blood collection devices are a potential source of pre-analytical error in laboratory testing. Accurate laboratory testing requires an understanding of the complex interactions between collection devices and blood specimens. Manufacturers, vendors, and clinical laboratorians must consider the pre-analytical challenges in laboratory testing. Although other authors have described the effects of endogenous substances on clinical assay results, the effects/impact of blood collection tube additives and components have not been well systematically described or explained. This review aims to identify and describe blood collection tube additives and their components and the strategies used to minimize their effects on clinical chemistry assays

Apolipoprotein Mimetic Peptides: A New Approach for the Treatment of Asthma

New treatments are needed for severe asthmatics to improve disease control and avoid severe toxicities associated with oral corticosteroids. We have used a murine model of house dust mite (HDM)-induced asthma to identify steroid-unresponsive genes that might represent targets for new therapeutic approaches for severe asthma. This strategy identified apolipoprotein E as a steroid-unresponsive gene with increased mRNA expression in the lungs of HDM-challenged mice. Furthermore, apolipoprotein E functioned as an endogenous negative regulator of airway hyperreactivity and goblet cell hyperplasia in experimental HDM-induced asthma. The ability of apolipoprotein E, which is expressed by lung macrophages, to attenuate AHR, and goblet cell hyperplasia is mediated by low density lipoprotein (LDL) receptors expressed by airway epithelial cells. Consistent with this, administration of an apolipoprotein E mimetic peptide, corresponding to amino acids 130–149 of the LDL receptor-binding domain of the holo-apoE protein, significantly reduced AHR and goblet cell hyperplasia in HDM-challenged apoE−/− mice. These findings identified the apolipoprotein E – LDL receptor pathway as a new druggable target for asthma that can be activated by administration of apoE-mimetic peptides. Similarly, apolipoprotein A-I may have therapeutic potential in asthma based upon its anti-inflammatory, anti-oxidative, and anti-fibrotic properties. Furthermore, administration of apolipoprotein A-I mimetic peptides has attenuated airway inflammation, airway remodeling, and airway hyperreactivity in murine models of experimental asthma. Thus, site-directed delivery of inhaled apolipoprotein E or apolipoprotein A-I mimetic peptides may represent novel treatment approaches that can be developed for asthma, including severe disease

High-density lipoprotein revisited: biological functions and clinical relevance

Previous interest in high-density lipoproteins (HDLs) focused on their possible protective role in atherosclerotic cardiovascular disease (ASCVD). Evidence from genetic studies and randomized trials, however, questioned that the inverse association of HDL-cholesterol (HDL-C) is causal. This review aims to provide an update on the role of HDL in health and disease, also beyond ASCVD. Through evolution from invertebrates, HDLs are the principal lipoproteins, while apolipoprotein B-containing lipoproteins first developed in vertebrates. HDLs transport cholesterol and other lipids between different cells like a reusable ferry, but serve many other functions including communication with cells and the inactivation of biohazards like bacterial lipopolysaccharides. These functions are exerted by entire HDL particles or distinct proteins or lipids carried by HDL rather than by its cholesterol cargo measured as HDL-C. Neither does HDL-C measurement reflect the efficiency of reverse cholesterol transport. Recent studies indicate that functional measures of HDL, notably cholesterol efflux capacity, numbers of HDL particles, or distinct HDL proteins are better predictors of ASCVD events than HDL-C. Low HDL-C levels are related observationally, but also genetically, to increased risks of infectious diseases, death during sepsis, diabetes mellitus, and chronic kidney disease. Additional, but only observational, data indicate associations of low HDL-C with various autoimmune diseases, and cancers, as well as all-cause mortality. Conversely, extremely high HDL-C levels are associated with an increased risk of age-related macular degeneration (also genetically), infectious disease, and all-cause mortality. HDL encompasses dynamic multimolecular and multifunctional lipoproteins that likely emerged during evolution to serve several physiological roles and prevent or heal pathologies beyond ASCVD. For any clinical exploitation of HDL, the indirect marker HDL-C must be replaced by direct biomarkers reflecting the causal role of HDL in the respective disease

Thematic Review Series: Functional Regulation of Lipid Homeostasis by microRNA: Complexity of microRNA function and the role of isomiRs in lipid homeostasis

MicroRNAs (miRNAs) are key posttranscriptional regulators of biological pathways that govern lipid metabolic phenotypes. Recent advances in high-throughput small RNA sequencing technology have revealed the complex and dynamic repertoire of miRNAs. Specifically, it has been demonstrated that a single genomic locus can give rise to multiple, functionally distinct miRNA isoforms (isomiR). There are several mechanisms by which isomiRs can be generated, including processing heterogeneity and posttranscriptional modifications, such as RNA editing, exonuclease-mediated nucleotide trimming, and/or nontemplated nucleotide addition (NTA). NTAs are dominant at the 3′-end of a miRNA, are most commonly uridylation or adenlyation events, and are catalyzed by one or more of several nucleotidyl transferase enzymes. 3′ NTAs can affect miRNA stability and/or activity and are physiologically regulated, whereas modifications to the 5′-ends of miRNAs likely alter miRNA targeting activity. Recent evidence also suggests that the biogenesis of specific miRNAs, or small RNAs that act as miRNAs, can occur through unconventional mechanisms that circumvent key canonical miRNA processing steps. The unveiling of miRNA diversity has significantly added to our view of the complexity of miRNA function. In this review we present the current understanding of the biological relevance of isomiRs and their potential role in regulating lipid metabolism

Lipoprotein particles in patients with pediatric Cushing disease and possible cardiovascular risks.

BackgroundCardiovascular (CV) complications are the most significant cause of mortality in adults with Cushing disease (CD); little is known about CV risk factors in children with CD. Measurement of lipoprotein particles by nuclear magnetic resonance (NMR) spectroscopy is a novel technology to assess CV risk. The objective of the current study is to analyze the NMR lipid profile in pediatric CD patients before and 1 year after remission.MethodsNMR lipid profile was obtained via the Vantera NMR analyzer, using frozen serum samples from 33 CD patients (mean age 13.8 ± 4.0 years) evaluated between 1997 and 2017 at the National Institutes of Health (NIH) Clinical Center (CC).ResultsGlycA (glycosylated acute-phase proteins), triglyceride-rich particles (TRLP medium and very small sizes), low-density lipoprotein (LDL) particles (LDLP total and large size), high-density lipoprotein (HDL) particles (HDLP total, medium and small sizes), total cholesterol, LDL-cholesterol, HDL-cholesterol, GlycA inflammatory biomarker, and apolipoprotein B and apolipoprotein A1 (ApoA1) concentrations showed statistically significant changes after remission of CD (p < 0.05).ConclusionIn our study population, most of the lipid variables improved post-CD remission, with the exception of HDL and ApoA1, indicating that NMR lipoprotein profile may be a helpful tool in assessing the CV risk in pediatric patients with CD

Lipoprotein lipase regulates hematopoietic stem progenitor cell maintenance through DHA supply.

Lipoprotein lipase (LPL) mediates hydrolysis of triglycerides (TGs) to supply free fatty acids (FFAs) to tissues. Here, we show that LPL activity is also required for hematopoietic stem progenitor cell (HSPC) maintenance. Knockout of Lpl or its obligatory cofactor Apoc2 results in significantly reduced HSPC expansion during definitive hematopoiesis in zebrafish. A human APOC2 mimetic peptide or the human very low-density lipoprotein, which carries APOC2, rescues the phenotype in apoc2 but not in lpl mutant zebrafish. Creating parabiotic apoc2 and lpl mutant zebrafish rescues the hematopoietic defect in both. Docosahexaenoic acid (DHA) is identified as an important factor in HSPC expansion. FFA-DHA, but not TG-DHA, rescues the HSPC defects in apoc2 and lpl mutant zebrafish. Reduced blood cell counts are also observed in Apoc2 mutant mice at the time of weaning. These results indicate that LPL-mediated release of the essential fatty acid DHA regulates HSPC expansion and definitive hematopoiesis

Proteomic Alterations of HDL in Youth with Type 1 Diabetes and their Associations with Glycemic Control: A Case-Control Study

Background: Patients with type 1 diabetes (T1DM) typically have normal or even elevated plasma high density lipoprotein (HDL) cholesterol concentrations; however, HDL protein composition can be altered without a change in cholesterol content. Alteration of the HDL proteome can result in dysfunctional HDL particles with reduced ability to protect against cardiovascular disease (CVD). The objective of this study was to compare the HDL proteomes of youth with T1DM and healthy controls (HC) and to evaluate the influence of glycemic control on HDL protein composition. Methods: This was a cross-sectional case–control study. Blood samples were obtained from patients with T1DM and HC. HDL was isolated from plasma by size-exclusion chromatography and further purified using a lipid binding resin. The HDL proteome was analyzed by mass spectrometry using label-free SWATH peptide quantification. Results: Samples from 26 patients with T1DM and 13 HC were analyzed and 78 HDL-bound proteins were measured. Youth with T1DM had significantly increased amounts of complement factor H related protein 2 (FHR2; adjusted P \u3c 0.05), compared to HC. When patients were analyzed based on glucose control, several trends emerged. Some proteins were altered in T1DM and not influenced by glycemic control (e.g. FHR2) while others were partially or completely corrected with optimal glucose control (e.g. alpha-1-beta glycoprotein, A1BG). In a subgroup of poorly controlled T1DM patients, inter alpha trypsin inhibitor 4 (ITIH4) was dramatically elevated (P \u3c 0.0001) and this was partially reversed in patients with optimal glucose control. Some proteins including complement component C3 (CO3) and albumin (ALB) were significantly different only in T1DM patients with optimal glucose control, suggesting a possible effect of exogenous insulin. Conclusions: Youth with T1DM have proteomic alterations of their HDL compared to HC, despite similar concentration of HDL cholesterol. The influence of these compositional changes on HDL function are not yet known. Future efforts should focus on investigating the role of these HDL associated proteins in regard to HDL function and their role in CVD risk in patients with T1DM. Trial registration NCT0227509

Determinants of HDL Cholesterol Efflux Capacity after Virgin Olive Oil Ingestion: Interrelationships with Fluidity of HDL Monolayer

Scope: Cholesterol efflux capacity of HDL (CEC) is inversely associated with cardiovascular risk. HDL composition, fluidity, oxidation, and size are related with CEC. We aimed to assess which HDL parameters were CEC determinants after virgin olive oil (VOO) ingestion. Methods and results: Post‐hoc analyses from the VOHF study, a crossover intervention with three types of VOO. We assessed the relationship of 3‐week changes in HDL‐related variables after intervention periods with independence of the type of VOO. After univariate analyses, mixed linear models were fitted with variables related with CEC and fluidity. Fluidity and Apolipoprotein (Apo)A‐I content in HDL was directly associated, and HDL oxidative status inversely, with CEC. A reduction in free cholesterol, an increase in triglycerides in HDL, and a decrease in small HDL particle number or an increase in HDL mean size, were associated to HDL fluidity. Conclusions: HDL fluidity, ApoA‐I concentration, and oxidative status are major determinants for CEC after VOO. The impact on CEC of changes in free cholesterol and triglycerides in HDL, and those of small HDL or HDL mean size, could be mechanistically linked through HDL fluidity. Our work points out novel therapeutic targets to improve HDL functionality in humans through nutritional or pharmacological interventions.Fil: Fernández Castillejo, Sara. Universitat Rovira I Virgili; EspañaFil: Rubió, Laura. Universitat Rovira I Virgili; España. Universidad de Lleida; EspañaFil: Hernáez, Álvaro. Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición; EspañaFil: Catalán, Úrsula. Universitat Rovira I Virgili; EspañaFil: Pedret, Anna. Universitat Rovira I Virgili; EspañaFil: Valls, Rosa M.. Universitat Rovira I Virgili; EspañaFil: Mosse, Juana Inés. Universidad de Lleida; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Covas, Maria Isabel. Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición; EspañaFil: Remaley, Alan T.. National Institutes of Health; Estados UnidosFil: Castañer, Olga. Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y Nutrición; EspañaFil: Motilva, Maria José. Universidad de Lleida; EspañaFil: Solá, Rosa. Universitat Rovira I Virgili; Españ

Effect of Metformin on the High-Density Lipoprotein Proteome in Youth with Type 1 Diabetes

Background: Youth with type 1 diabetes (T1D) have normal or elevated High-Density Lipoprotein Cholesterol (HDL-C), however, the function of HDL, partly mediated by the HDL proteome, may be impaired. Metformin can be used as an adjunct therapy in youth with T1D, but its effects on the HDL proteome are unknown. Objective: To determine the effect of metformin on the HDL proteome. Subjects: Youth (12-20 years old) with T1D who had a BMI \u3e 90th percentile, HbA1c \u3e 8.0% and Tanner stage 5. Methods: Double-blinded, placebo-controlled randomized sub-study. We examined the effects of metformin (n = 25) or placebo (n = 10) after 6 months on HDL proteome. Changes in HDL proteins were measured by data-independent acquisition (DIA) mass spectrometry and compared between treatment groups. As a secondary outcome, associations between proteins of interest and the most studied function of HDL, the cholesterol efflux capacity (CEC), was examined. Results: The relative abundance of 84 HDL-associated proteins were measured. Two proteins were significantly affected by metformin treatment, peptidoglycan recognition protein 2 (PGRP2; +23.4%, p = .0058) and alpha-2-macroglobulin (A2MG; +29.8%, p = .049). Metformin did not significantly affect CEC. Changes in affected HDL proteins did not correlate with CEC. Conclusions: Despite having little effect on HDL-C, metformin increased PGRP2 and A2MG protein on HDL in youth with T1D, but had no significant effect on CEC. Further studies are needed to understand the impact of PGRP2 and A2MG on other HDL functions