Impact of Sepsis on High-Density Lipoprotein Metabolism

Background: High-density lipoproteins (HDL) are thought to play a protective role in sepsis through several mechanisms, such as promotion of steroid synthesis, clearing bacterial toxins, protection of the endothelial barrier, and antioxidant/inflammatory activities. However, HDL levels decline rapidly during sepsis, but the contributing mechanisms are poorly understood.Methods/Aim: In the present study, we investigated enzymes involved in lipoprotein metabolism in sepsis and non-sepsis patients admitted to the intensive care unit (ICU).Results: In 53 ICU sepsis and 25 ICU non-sepsis patients, we observed significant differences in several enzymes involved in lipoprotein metabolism. Lecithin-cholesterol acyl transferase (LCAT) activity, LCAT concentration, and cholesteryl transfer protein (CETP) activity were significantly lower, whereas phospholipid transfer activity protein (PLTP) and endothelial lipase (EL) were significantly higher in sepsis patients compared to non-sepsis patients. In addition, serum amyloid A (SAA) levels were increased 10-fold in sepsis patients compared with non-sepsis patients. Furthermore, we found that LCAT activity was significantly associated with ICU and 28-day mortality whereas SAA levels, representing a strong inflammatory marker, did not associate with mortality outcomes.Conclusion: We provide novel data on the rapid and robust changes in HDL metabolism during sepsis. Our results clearly highlight the critical role of specific metabolic pathways and enzymes in sepsis pathophysiology that may lead to novel therapeutics.

Double heterozygous familial hypercholesterolaemia: Case series, genetics and Cascade screening of families

Background: Familial hypercholesterolemia (FH) is an autosomal dominant disorder of lipoprotein metabolism characterized by high levels of LDL-cholesterol (LDL-C) in the blood. Studies identified more than 1,000 mutations of the LDLR gene in FH patients with incidence rates between 1: 500 and 1: 300. The mutation that occurs primarily in: LDLR, apoB, PCSK9, LDLRAP1 genes, 80% of which were detected the LDLR gene mutation. Nowaday, FH disease has not been paid much attention, leading to a delay in treatment. Objectives: identify mutations in other family members of the patient FH. Subjects and Methods: 14 family members of FH patients were gene analyzed, identified mutations on exons 4, 9 LDLR genes. Results: 11/15 family members carrying heterozygous mutations on exon 4 and exon 9 of LDLR gene. Patient and 1 family member detected and treated late, leading to complications of myocardial infarction. Conclusion: Therefore, Cascade screening of patient's family members has an important role in early detection, genetic counseling and treatment, even in cases where pedigree members do not have xanthomas and no increase or slight increase in blood lipids. This is the basis for early counseling and treatment for members with mutations, reducing the risk of coronary artery diseases in the future.

Systems epidemiology of metabolomics measures reveals new relationships between lipoproteins and other small molecules

Introduction The study of lipoprotein metabolism at the population level can provide valuable information for the organisation of lipoprotein related processes in the body. To use this information towards interventional hypotheses generation and testing, we need to be able to identify the mechanistic connections among the large number of observed correlations between the measured components of the system. Objectives To use population level metabolomics information to gain insight on their biochemical networks and metabolism. Methods Genetic and metabolomics information for 230 metabolic measures, predominately lipoprotein related, from a targeted nuclear magnetic resonance approach, in two samples of an established European cohort, totalling more than 9400 individuals analysed using phenotypic and genetic correlations, as well as Mendelian Randomisation. Results More than 20,500 phenotypic correlations were identified in the data, with almost 2000 also showing evidence of strong genetic correlation. Mendelian randomisation, provided evidence for a causal effect between 9496 pairs of metabolic measures, mainly between lipoprotein traits. The results provide insights on the organisation of lipoproteins in three distinct classes, the heterogeneity between HDL particles, and the association, or lack of, between CLA, glycolysis markers, such as glucose and citrate, and glycoproteins with lipids subfractions. Two examples for the use of the approach in systems biology of lipoproteins are presented. Conclusions Genetic variation can be used to infer the underlying mechanisms for the associations between lipoproteins for hypothesis generation and confirmation, and, together with biological information, to map complex biological processes.

Structural and Functional Changes of Reconstituted High-Density Lipoprotein (HDL) by Incorporation of α-synuclein: A Potent Antioxidant and Anti-Glycation Activity of α-synuclein and apoA-I in HDL at High Molar Ratio of α-synuclein

α-synuclein (α-syn) is a major culprit of Parkinson’s disease (PD), although lipoprotein metabolism is very important in the pathogenesis of PD. α-syn was expressed and purified using the pET30a expression vector from an E. coli expression system to elucidate the physiological effects of α-syn on lipoprotein metabolism. The human α-syn protein (140 amino acids) with His-tag (8 amino acids) was expressed and purified to at least 95% purity. Isoelectric focusing gel electrophoresis showed that the isoelectric point (pI) of α-syn and apoA-I were pI = 4.5 and pI = 6.4, respectively. The lipid-free α-syn showed almost no phospholipid-binding ability, while apoA-I showed rapid binding ability with a half-time (T1/2) = 8 ± 0.7 min. The α-syn and apoA-I could be incorporated into the reconstituted HDL (rHDL, molar ratio 95:5:1:1, palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC):cholesterol:apoA-I:α-syn with the production of larger particles (92 Å) than apoA-I-rHDL (86 and 78 Å) and α-syn-rHDL (65 Å). An rHDL containing both apoA-I and α-syn showed lower α-helicity around 45% with a red shift of the Trp wavelength maximum fluorescence (WMF) from 339 nm, while apoA-I-HDL showed 76% α-helicity and 337 nm of WMF. The denaturation by urea addition showed that the incorporation of α-syn in rHDL caused a larger increase in the WMF than apoA-I-rHDL, suggesting that the destabilization of the secondary structure of apoA-I by the addition of α-syn. On the other hand, the addition of α-syn induced two-times higher resistance to rHDL glycation at apoA-I:α-syn molar ratios of 1:1 and 1:2. Interestingly, low α-syn in rHDL concentrations, molar ratio of 1:0.5 (apoA-I:α-syn), did not prevent glycation with more multimerization of apoA-I. In the lipid-free and lipid-bound state, α-syn showed more potent antioxidant activity than apoA-I against cupric ion-mediated LDL oxidation. On the other hand, microinjection of α-syn (final 2 μM) resulted in 10% less survival of zebrafish embryos than apoA-I. A subcutaneous injection of α-syn (final 34 μM) resulted in less tail fin regeneration than apoA-I. Interestingly, incorporation of α-syn at a low molar ratio (apoA-I:α-syn, 1:0.5) in rHDL resulted destabilization of the secondary structure and impairment of apoA-I functionality via more oxidation and glycation. However, at a higher molar ratio of α-syn in rHDL (apoA-I:α-syn = 1:1 or 1:2) exhibited potent antioxidant and anti-glycation activity without aggregation. In conclusion, there might be a critical concentration of α-syn and apoA-I in HDL-like complex to prevent the aggregation of apoA-I via structural and functional enhancement.

Relationship between administration of statins and blood serum levels of selected biochemical parameters

Results of biochemical tests of 172 patient data (among them 84 men data and 88 women data, resp.) before and after administration of statins were studied. All monitored patients are characterized by lipoprotein metabolism failure or other kind of lipidaemia. The calculations were performed using several chemometrical methods pursuing visualization of most important biochemical parameters and classification of the patient blood samples by means of up-to-date software packages. The dependences of the content of most common biochemical parameters upon the treatment of patients by statins were elucidated in detail.

Comparison of ten biochemical laboratory tests before and after treatment by statins

Results of 10 biochemical tests of 172 patient data (among them 84 men data and 88 women data, resp.) before and after administration of statins were thoroughly studied. All monitored patients are characterized by disorders of lipoprotein metabolism or other kind of dislipidaemia. The calculations were performed using four chemometrical methods facilitating quantification and visualization of the statin effect upon most important biochemical parameters, mainly lipid markers, and allowing classification of the patient blood samples taking into account whether the patient has been or has not been medicated by a statin drug.

Mosaic loss of chromosome Y in aged human microglia.

Mosaic loss of chromosome Y (LOY) is a particularly common acquired structural mutation in the leukocytes of aging men and it has been shown to correlate with several age-related diseases including Alzheimer's disease (AD). To derive the molecular basis of LOY in brain cells, we create an integrated resource by aggregating data from 21 single-cell and single-nuclei RNA brain studies, yielding 763,410 cells to investigate the presence and cell-type specific burden of LOY. We created robust quantification metrics for assessing LOY, which were validated using a multi-modal dataset. Using this new resource and LOY-quantification approach, we found that LOY frequencies differed widely between CNS cell-types and individual donors. Among five common neural cell types, microglia were most affected by LOY (7.79%, n=41,949), while LOY in neurons was rare (0.48%, n=220,010). Differential gene expression analysis in microglia found 188 autosomal genes, 6 X-linked genes, and 11 pseudoautosomal genes, pointing to broad dysregulation in lipoprotein metabolism, inflammatory response, and antigen processing that coincides with loss of Y. To our knowledge, we provide the first evidence of LOY in the microglia, and highlight its potential roles in aging and the pathogenesis of neurodegenerative disorders such as AD.

Genetic Profile of Endotoxemia Reveals an Association With Thromboembolism and Stroke

Background Translocation of lipopolysaccharide from gram‐negative bacteria into the systemic circulation results in endotoxemia. In addition to acute infections, endotoxemia is detected in cardiometabolic disorders, such as cardiovascular diseases and obesity. Methods and Results We performed a genome‐wide association study of serum lipopolysaccharide activity in 11 296 individuals from 6 different Finnish study cohorts. Endotoxemia was measured by limulus amebocyte lysate assay in the whole population and by 2 other techniques (Endolisa and high‐performance liquid chromatography/tandem mass spectrometry) in subpopulations. The associations of the composed genetic risk score of endotoxemia and thrombosis‐related clinical end points for 195 170 participants were analyzed in FinnGen. Lipopolysaccharide activity had a genome‐wide significant association with 741 single‐nucleotide polymorphisms in 5 independent loci, which were mainly located at genes affecting the contact activation of the coagulation cascade and lipoprotein metabolism and explained 1.5% to 9.2% of the variability in lipopolysaccharide activity levels. The closest genes included KNG1 , KLKB1 , F12 , SLC34A1 , YPEL4 , CLP1 , ZDHHC5 , SERPING1 , CBX5 , and LIPC . The genetic risk score of endotoxemia was associated with deep vein thrombosis, pulmonary embolism, pulmonary heart disease, and venous thromboembolism. Conclusions The biological activity of lipopolysaccharide in the circulation (ie, endotoxemia) has a small but highly significant genetic component. Endotoxemia is associated with genetic variation in the contact activation pathway, vasoactivity, and lipoprotein metabolism, which play important roles in host defense, lipopolysaccharide neutralization, and thrombosis, and thereby thromboembolism and stroke.

Transcriptomic therapy for dyslipidemias utilizing nucleic acids targeted at ANGPTL3

Angiopoietin-like protein 3 (ANGPTL3) is a key physiological regulator of plasma lipid and lipoprotein metabolism that involves the control of enzymes, lipoprotein and endothelial lipases. Inhibition of ANGPTL3 offers a new approach for correcting the health risks of dyslipidemia, including familial hypercholesterolemia, mixed hyperlipidemia, metabolic syndrome and/or severe hypertriglyceridemia. ANGPTL3 inhibition with nucleic acid-based antisense oligonucleotide and siRNA can correct dyslipidemia chiefly by reducing production and increasing catabolism of triglyceride-rich lipoprotein and LDL particles. Early clinical trials have demonstrated that these agents can safely and effectively lower plasma triglyceride and LDL-cholesterol levels by up to 70 and 50%, respectively. However, the long-term safety and cost–effectiveness of these agents await to be confirmed in an ongoing and future clinical trials.