👤 Keran Moll

Lipoprotein kinetics are a crucial factor in understanding lipoprotein metabolism because a prolonged time in circulation can contribute to the atherogenic character of B-lps (ApoB-containing lipoproteins). We developed a genetically encoded B-Lp reporter, LipoTimer, in which the zebrafish endogenous By quantifying the red population of ApoB-Dendra2 over time, we found that B-lp turnover in wild-type larvae becomes faster as development proceeds. Mutants with impaired B-lp uptake or lipolysis present with increased B-lp levels and half-life. In contrast, mutants with impaired B-lp triglyceride loading display slightly fewer and smaller B-lps, which have a significantly shorter B-lp half-life. Furthermore, we showed that chronic high-cholesterol feeding is associated with a longer B-lp half-life in wild-type juveniles but does not lead to changes in B-lp half-life in lipolysis-deficient In conclusion, the new LipoTimer reporter allows for direct in vivo examination of B-lp kinetics, which can be used to better understand the role of lipoprotein modifier genes and environmental factors (eg, diet) on B-lp lifetime. Show less

Apolipoprotein B (ApoB) and lipoprotein (a) (Lp[a]) are predictors of cardiovascular disease (CVD) risk; therefore, current recommendations for CVD risk assessment and management advocate that patients receive testing for ApoB and Lp(a) in addition to the standard lipid panel. However, US guidelines around ApoB and Lp(a) testing have evolved over time and vary slightly by expert committee. The objective of this analysis was to estimate the number of insured individuals in the USA who received any component of a lipid test, or ApoB and/or Lp(a) testing, during 2019. We conducted a cross-sectional analysis to estimate the prevalence of any component of a lipid test, ApoB, and/or Lp(a) in the USA using four different claim data sources (including Medicaid, Medicare, and commercially insured enrollees). Prevalence estimates were age-, sex-, payor-, and region-standardized to the 2019 US Annual Social and Economic Supplement of the Current Population Survey. We also described the clinical profile of patients who received lipid testing between 2019 and 2021 (cohort analysis) in Optum claims database. Enrollees were grouped into four non-mutually exclusive cohorts based on their completion of any component of the lipid panel, ApoB, Lp(a), or ApoB and Lp(a). In the prevalence cohort, over a third (38 %) of insured adults in the USA underwent testing for any component of a lipid panel in 2019. This proportion was higher for individuals aged ≥65 years compared to younger adults (62% vs 31 %). The proportion of ApoB and Lp(a) testing represented only <1 % of testing for any component of a lipid panel. In the cohort analysis, we found that lipid testing increased with age and comorbidities. These data should be considered by guideline-issuing agencies and organizations to develop education campaigns encouraging more frequent use of tests beyond the standard lipid panel. Show less

Zebrafish are an ideal model organism to study lipid metabolism and to elucidate the molecular underpinnings of human lipid-associated disorders. Unlike murine models, to which various standardized high lipid diets such as a high-cholesterol diet (HCD) are available, there has yet to be a uniformly adopted zebrafish HCD protocol. In this study, we have developed an improved HCD protocol and thoroughly tested its impact on zebrafish lipid deposition and lipoprotein regulation in a dose- and time-dependent manner. The diet stability, reproducibility, and fish palatability were also validated. Fish fed HCD developed hypercholesterolemia as indicated by significantly elevated ApoB-containing lipoproteins (ApoB-LPs) and increased plasma levels of cholesterol and cholesterol esters. Feeding of the HCD to larvae for 8 days produced hepatic steatosis that became more stable and sever after 1 day of fasting and was associated with an opaque liver phenotype (dark under transmitted light). Unlike larvae, adult fish fed HCD for 14 days followed by a 3-day fast did not develop a stable fatty liver phenotype, though the fish had higher ApoB-LP levels in plasma and an upregulated lipogenesis gene fasn in adipose tissue. In conclusion, our HCD zebrafish protocol represents an effective and reliable approach for studying the temporal characteristics of the physiological and biochemical responses to high levels of dietary cholesterol and provides insights into the mechanisms that may underlie fatty liver disease. Show less

Cytokines control immune related events and are critically involved in a plethora of patho-physiological processes including autoimmunity and cancer development. In rare cases, single nucleotide polymorphisms (SNPs) or single nucleotide variations (SNVs) in cytokine receptors eventually cause detrimental ligand-independent, constitutive activation of signal transduction. Most SNPs have, however, no or only marginal influences on gene expression, protein stability, localization and function and thereby only slightly affecting pathogenesis probability. The SNP database (dbSNP) is an archive for a broad collection of polymorphisms in which SNPs are categorized and marked with a locus accession number "reference SNP" (rs). Here, we engineered an algorithm to directly align dbSNP information to DNA and protein sequence information to clearly illustrate a genetic SNP landscape exemplified for all tall cytokine receptors of the IL-6/IL-12 family, including IL-23R, IL-12Rβ1, IL-12Rβ2, gp130, LIFR, OSMR and WSX-1. This information was complemented by a comprehensive literature summary and structural insights of relevant disease-causing SNPs in cytokine/cytokine receptor interfaces. In summary, we present a general strategy with potential to apply to other cytokine receptor networks. Show less

Nutrients are transported through endothelial cells before being metabolized in muscle cells. However, little is known about the regulation of endothelial transport processes. Notch signaling is a critical regulator of metabolism and angiogenesis during development. Here, we studied how genetic and pharmacological manipulation of endothelial Notch signaling in adult mice affects endothelial fatty acid transport, cardiac angiogenesis, and heart function. Endothelial-specific Notch inhibition was achieved by conditional genetic inactivation of Rbp-jκ in adult mice to analyze fatty acid metabolism and heart function. Wild-type mice were treated with neutralizing antibodies against the Notch ligand Delta-like 4. Fatty acid transport was studied in cultured endothelial cells and transgenic mice. Treatment of wild-type mice with Delta-like 4 neutralizing antibodies for 8 weeks impaired fractional shortening and ejection fraction in the majority of mice. Inhibition of Notch signaling specifically in the endothelium of adult mice by genetic ablation of Rbp-jκ caused heart hypertrophy and failure. Impaired heart function was preceded by alterations in fatty acid metabolism and an increase in cardiac blood vessel density. Endothelial Notch signaling controlled the expression of endothelial lipase, Angptl4, CD36, and Fabp4, which are all needed for fatty acid transport across the vessel wall. In endothelial-specific Rbp-jκ-mutant mice, lipase activity and transendothelial transport of long-chain fatty acids to muscle cells were impaired. In turn, lipids accumulated in the plasma and liver. The attenuated supply of cardiomyocytes with long-chain fatty acids was accompanied by higher glucose uptake, increased concentration of glycolysis intermediates, and mTOR-S6K signaling. Treatment with the mTOR inhibitor rapamycin or displacing glucose as cardiac substrate by feeding a ketogenic diet prolonged the survival of endothelial-specific Rbp-jκ-deficient mice. This study identifies Notch signaling as a novel regulator of fatty acid transport across the endothelium and as an essential repressor of angiogenesis in the adult heart. The data imply that the endothelium controls cardiomyocyte metabolism and function. Show less