HDL in CKD-The Devil Is in the Detail Kronenberg, Florian
Journal of the American Society of Nephrology,
05/2018, Letnik:
29, Številka:
5
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The picture of HDL cholesterol (HDL-C) as the "good" cholesterol has eroded. This is even more surprising because there exists strong evidence that HDL-C is associated with cardiovascular disease ...(CVD) in the general population as well as in patients with impairment of kidney function and/or progression of CKD. However, drugs that dramatically increase HDL-C have mostly failed to decrease CVD events. Furthermore, genetic studies took the same line, as genetic variants that have a pronounced influence on HDL-C concentrations did not show an association with cardiovascular risk. For many, this was not surprising, given that an HDL particle is highly complex and carries >80 proteins and several hundred lipid species. Simply measuring cholesterol might not reflect the variety of biologic effects of heterogeneous HDL particles. Therefore, functional studies and the involvement of HDL components in the reverse cholesterol transport, including the cholesterol efflux capacity, have become a further focus of study during recent years. As also observed for other aspects, CKD populations behave differently compared with non-CKD populations. Although clear disturbances have been observed for the "functionality" of HDL particles in patients with CKD, this did not necessarily translate into clear-cut associations with outcomes.
Lipoprotein(a) Lp(a) is a highly atherogenic lipoprotein that is under strong genetic control by the
LPA
gene locus. Genetic variants including a highly polymorphic copy number variation of the so ...called kringle IV repeats at this locus have a pronounced influence on Lp(a) concentrations. High concentrations of Lp(a) as well as genetic variants which are associated with high Lp(a) concentrations are both associated with cardiovascular disease which very strongly supports causality between Lp(a) concetrations and cardiovascular disease. This method of using a genetic variant that has a pronounced influence on a biomarker to support causality with an outcome is called Mendelian randomization approach and was applied for the first time two decades ago with data from Lp(a) and cardiovascular disease. This approach was also used to demonstrate a causal association between high Lp(a) concentrations and aortic valve stenosis, between low concentrations and type-2 diabetes mellitus and to exclude a causal association between Lp(a) concentrations and venous thrombosis. Considering the high frequency of these genetic variants in the population makes Lp(a) the strongest genetic risk factor for cardiovascular disease identified so far. Promising drugs that lower Lp(a) are on the horizon but their efficacy in terms of reducing clinical outcomes still has to be shown.
High lipoprotein(a) Lp(a) concentrations are one of the most important genetically determined risk factors for cardiovascular disease. Lp(a) concentrations are an enigmatic trait largely controlled ...by one single gene (LPA) that contains a complex interplay of several genetic elements with many surprising effects discussed in this review. A hypervariable coding copy number variation (the kringle IV type-2 repeat, KIV-2) generates >40 apolipoprotein(a) protein isoforms and determines the median Lp(a) concentrations. Carriers of small isoforms with up to 22 kringle IV domains have median Lp(a) concentrations up to 5 times higher than those with large isoforms (>22 kringle IV domains). The effect of the apo(a) isoforms are, however, modified by many functional single nucleotide polymorphisms (SNPs) distributed over the complete range of allele frequencies (<0.1% to >20%) with very pronounced effects on Lp(a) concentrations. A complex interaction is present between the apo(a) isoforms and LPA SNPs, with isoforms partially masking the effect of functional SNPs and, vice versa, SNPs lowering the Lp(a) concentrations of affected isoforms. This picture is further complicated by SNP-SNP interactions, a poorly understood role of other polymorphisms such as short tandem repeats and linkage structures that are poorly captured by common R2 values. A further layer of complexity derives from recent findings that several functional SNPs are located in the KIV-2 repeat and are thus not accessible to conventional sequencing and genotyping technologies. A critical impact of the ancestry on correlation structures and baseline Lp(a) values becomes increasingly evident.
This review provides a comprehensive overview on the complex genetic architecture of the Lp(a) concentrations in plasma, a field that has made tremendous progress with the introduction of new technologies. Understanding the genetics of Lp(a) might be a key to many mysteries of Lp(a) and booster new ideas on the metabolism of Lp(a) and possible interventional targets.
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•Lipoprotein(a) is the lipoprotein with the strongest genetic regulation.•Many functional SNPs dissociate apo(a) isoform size and Lp(a) concentrations.•Multiple functional SNPs have been hidden in the KIV type-2 region until recently.•It is common that functional LPA SNPs occur only in defined isoform size ranges.•Multiple levels of linkage disequilibrium between polymorphisms govern the trait.
Chronic kidney disease (CKD) is a common condition with an increasing prevalence. A number of comorbidities are associated with CKD and prognosis is poor, with many patients experiencing disease ...progression. Recognizing the factors associated with CKD progression enables high-risk patients to be identified and given more intensive treatment if necessary. The identification of new predictive markers might improve our understanding of the pathogenesis and progression of CKD. This Review discusses a number of emerging factors and markers for which epidemiological evidence from prospective studies indicates an association with progression of CKD. The following factors and markers are discussed: asymmetric dimethylarginine, factors involved in calcium-phosphate metabolism, adrenomedullin, A-type natriuretic peptide, N-terminal pro-brain natriuretic peptide, liver-type fatty acid binding protein, kidney injury molecule 1, neutrophil gelatinase-associated lipocalin, apolipoprotein A-IV, adiponectin and some recently identified genetic polymorphisms. Additional epidemiological and experimental data are required before these markers can be broadly used for the prediction of CKD progression and before the risk factors can be considered as potential drug targets in clinical interventional trials.
Structure, function, and genetics of lipoprotein (a) Schmidt, Konrad; Noureen, Asma; Kronenberg, Florian ...
Journal of lipid research,
August 2016, 2016-08-00, 20160801, 2016-08-01, Letnik:
57, Številka:
8
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Lipoprotein (a) Lp(a) has attracted the interest of researchers and physicians due to its intriguing properties, including an intragenic multiallelic copy number variation in the LPA gene and the ...strong association with coronary heart disease (CHD). This review summarizes present knowledge of the structure, function, and genetics of Lp(a) with emphasis on the molecular and population genetics of the Lp(a)/LPA trait, as well as aspects of genetic epidemiology. It highlights the role of genetics in establishing Lp(a) as a risk factor for CHD, but also discusses uncertainties, controversies, and lack of knowledge on several aspects of the genetic Lp(a) trait, not least its function.
Mitochondrial DNA (mtDNA) profiles can be classified into phylogenetic clusters (haplogroups), which is of great relevance for evolutionary, forensic and medical genetics. With the extensive growth ...of the underlying phylogenetic tree summarizing the published mtDNA sequences, the manual process of haplogroup classification would be too time-consuming. The previously published classification tool HaploGrep provided an automatic way to address this issue. Here, we present the completely updated version HaploGrep 2 offering several advanced features, including a generic rule-based system for immediate quality control (QC). This allows detecting artificial recombinants and missing variants as well as annotating rare and phantom mutations. Furthermore, the handling of high-throughput data in form of VCF files is now directly supported. For data output, several graphical reports are generated in real time, such as a multiple sequence alignment format, a VCF format and extended haplogroup QC reports, all viewable directly within the application. In addition, HaploGrep 2 generates a publication-ready phylogenetic tree of all input samples encoded relative to the revised Cambridge Reference Sequence. Finally, new distance measures and optimizations of the algorithm increase accuracy and speed-up the application. HaploGrep 2 can be accessed freely and without any registration at http://haplogrep.uibk.ac.at.
Lipoprotein(a): the revenant Gencer, Baris; Kronenberg, Florian; Stroes, Erik S ...
European heart journal,
05/2017, Letnik:
38, Številka:
20
Journal Article
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In the mid-1990s, the days of lipoprotein(a) Lp(a) were numbered and many people would not have placed a bet on this lipid particle making it to the next century. However, genetic studies brought ...Lp(a) back to the front-stage after a Mendelian randomization approach used for the first time provided strong support for a causal role of high Lp(a) concentrations in cardiovascular disease and later also for aortic valve stenosis. This encouraged the use of therapeutic interventions to lower Lp(a) as well numerous drug developments, although these approaches mainly targeted LDL cholesterol, while the Lp(a)-lowering effect was only a 'side-effect'. Several drug developments did show a potent Lp(a)-lowering effect but did not make it to endpoint studies, mainly for safety reasons. Currently, three therapeutic approaches are either already in place or look highly promising: (i) lipid apheresis (specific or unspecific for Lp(a)) markedly decreases Lp(a) concentrations as well as cardiovascular endpoints; (ii) PCSK9 inhibitors which, besides lowering LDL cholesterol also decrease Lp(a) by roughly 30%; and (iii) antisense therapy targeting apolipoprotein(a) which has shown to specifically lower Lp(a) concentrations by up to 90% in phase 1 and 2 trials without influencing other lipids. Until the results of phase 3 outcome studies are available for antisense therapy, we will have to exercise patience, but with optimism since never before have we had the tools we have now to prove Koch's extrapolated postulate that lowering high Lp(a) concentrations might be protective against cardiovascular disease.
Rewiring of energy metabolism and adaptation of mitochondria are considered to impact on prostate cancer development and progression. Here, we report on mitochondrial respiration, DNA mutations and ...gene expression in paired benign/malignant human prostate tissue samples. Results reveal reduced respiratory capacities with NADH-pathway substrates glutamate and malate in malignant tissue and a significant metabolic shift towards higher succinate oxidation, particularly in high-grade tumors. The load of potentially deleterious mitochondrial-DNA mutations is higher in tumors and associated with unfavorable risk factors. High levels of potentially deleterious mutations in mitochondrial Complex I-encoding genes are associated with a 70% reduction in NADH-pathway capacity and compensation by increased succinate-pathway capacity. Structural analyses of these mutations reveal amino acid alterations leading to potentially deleterious effects on Complex I, supporting a causal relationship. A metagene signature extracted from the transcriptome of tumor samples exhibiting a severe mitochondrial phenotype enables identification of tumors with shorter survival times.
Abstract
This 2022 European Atherosclerosis Society lipoprotein(a) Lp(a) consensus statement updates evidence for the role of Lp(a) in atherosclerotic cardiovascular disease (ASCVD) and aortic valve ...stenosis, provides clinical guidance for testing and treating elevated Lp(a) levels, and considers its inclusion in global risk estimation. Epidemiologic and genetic studies involving hundreds of thousands of individuals strongly support a causal and continuous association between Lp(a) concentration and cardiovascular outcomes in different ethnicities; elevated Lp(a) is a risk factor even at very low levels of low-density lipoprotein cholesterol. High Lp(a) is associated with both microcalcification and macrocalcification of the aortic valve. Current findings do not support Lp(a) as a risk factor for venous thrombotic events and impaired fibrinolysis. Very low Lp(a) levels may associate with increased risk of diabetes mellitus meriting further study. Lp(a) has pro-inflammatory and pro-atherosclerotic properties, which may partly relate to the oxidized phospholipids carried by Lp(a). This panel recommends testing Lp(a) concentration at least once in adults; cascade testing has potential value in familial hypercholesterolaemia, or with family or personal history of (very) high Lp(a) or premature ASCVD. Without specific Lp(a)-lowering therapies, early intensive risk factor management is recommended, targeted according to global cardiovascular risk and Lp(a) level. Lipoprotein apheresis is an option for very high Lp(a) with progressive cardiovascular disease despite optimal management of risk factors. In conclusion, this statement reinforces evidence for Lp(a) as a causal risk factor for cardiovascular outcomes. Trials of specific Lp(a)-lowering treatments are critical to confirm clinical benefit for cardiovascular disease and aortic valve stenosis.
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