👤 Stephan Lorenz

Lipoprotein(a) [Lp(a)] is a known independent risk factor for cardiovascular disease, yet awareness and management remain limited. The psychosocial implications of elevated Lp(a)-levels have been poorly characterized. To compare cardiovascular outcomes and cardiovascular risk factor (CVRF) modification in individuals with normal vs. elevated Lp(a) levels, and to assess the impact of individualized prevention recommendations. For the first time, the individual psychological stress caused by Lp(a) is being surveyed. The ELITE study is a prospective, interventional cohort study conducted in north-western Germany. Participants were regularly assessed for CVRFs, including Lp(a), hypertension, dyslipidemia, diabetes mellitus, weight, nicotine - as well as lipoprotein (a), physical activity, dietary habits, depression and stress. They received written, personalized prevention recommendations. Follow-up averaged 4.4 years. Two groups were analyzed: Group 1 (Gr1, n=3,241) with normal Lp(a), and Group 2 (Gr2, n=841) with elevated Lp(a ≥75 nmol/l). Gr2 (mean Lp(a) 154.8 nmol/l) and Gr1 (mean Lp(a) 16.4 nmol/l) were comparable in age (~53 years) and sex distribution (~49% female). Most participants with elevated Lp(a) were previously unaware of their levels; 30% were referred to specialists, and ~40% reported concern or anxiety. Combined cardiovascular endpoints (CHD, stroke, heart failure, PAD, carotid stenosis, AF) occurred significantly more often in Gr2 (p<0.001), despite similar CVRF profiles, except for higher baseline LDL-C in Gr2 (p<0.001). Hypertension (61%) and physical inactivity (57%) were the most prevalent CVRFs. Personalized prevention measures led to significant improvements in blood pressure, LDL-C, smoking, physical activity, and weight in both groups. Lipid-lowering therapy improved markedly in Gr2 (12% to 23%). Elevated Lp(a) is associated with a significantly higher rate of cardiovascular events, independent of traditional CVRFs. This confirms a causal role of Lp(a) in CV morbidity. Personalized written prevention recommendations improved CVRFs across both groups, though further optimization is needed. Notably, elevated Lp(a) also imposes a psychosocial burden, underlining the need for enhanced education, counseling, and clinical pathways. Show less

Skeletal muscle differentiation is an essential process in embryonic development as well as regeneration and repair throughout the lifespan. It is well-known that dietary fat intake impacts biological and physiological function in skeletal muscle, however, understanding of the contribution of nutritional factors in skeletal muscle differentiation is limited. Therefore, the objective of the current study was to evaluate the effects of free fatty acids (FFAs) on skeletal muscle differentiation in vitro. We used C2C12 murine myoblasts and treated them with various FFAs, which revealed a unique response of angiopoietin-like protein-4 (ANGPTL4) with linoleic acid (LA) treatment that was associated with reduced differentiation. LA significantly inhibited myotube formation and lowered the protein expression of myogenic regulatory factors, including MyoD and MyoG and increased Pax7 during cell differentiation. Next, recombinant ANGPTL4 protein or siRNA knockdown of ANGPTL4 was employed to examine its role in skeletal muscle differentiation, and we confirmed that ANGPTL4 knockdown at day two and six of differentiation restored myotube formation in the presence of LA. RNA-sequencing analysis revealed that ANGPTL4-mediated inhibition of skeletal muscle differentiation at day two as well as LA at day two or -6 led to a reduction in Wnt/β-catenin signaling pathways. We confirmed that LA reduced Wnt11 and Axin2 while increasing expression of the Wnt inhibitor, Dkk2. ANGPTL4 knockdown increased β-catenin protein in the nucleus in response to LA and increased Axin2 and Wnt11 expression. Taken together, these results demonstrate that LA induced ANGPTL4 inhibits C2C12 differentiation by suppressing Wnt/β-catenin signaling. Show less

Variants in cardiac myosin-binding protein C (cMyBP-C) are the leading cause of inherited hypertrophic cardiomyopathy (HCM), demonstrating the key role that cMyBP-C plays in the heart's contractile machinery. To investigate the Show less

Targeting of the glucose-dependent insulinotropic polypeptide receptor (GIPR) is an emerging strategy in antidiabetic drug development. The aim of this study was to develop a positron emission tomography (PET) radioligand for the GIPR to enable the assessment of target distribution and drug target engagement in vivo. The GIPR-selective peptide S02-GIP was radiolabeled with Show less

Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) regulates cardiac contraction through modulation of actomyosin interactions mediated by the protein's amino terminal (N')-region (C0-C2 domains, 358 amino acids). On the other hand, dephosphorylation of cMyBP-C during myocardial injury results in cleavage of the 271 amino acid C0-C1f region and subsequent contractile dysfunction. Yet, our current understanding of amino terminus region of cMyBP-C in the context of regulating thin and thick filament interactions is limited. A novel cardiac-specific transgenic mouse model expressing cMyBP-C, but lacking its C0-C1f region (cMyBP-C Show less

To test specific mono-agonists to the glucagon-like peptide-1 receptor (GLP-1R), glucagon receptor (GCGR) and glucose-dependent insulinotropic peptide receptor (GIPR), individually and in combination, in a mouse model of diet-induced non-alcoholic steatohepatitis (NASH) and fibrosis in order to decipher the contribution of their activities and potential additive effects to improving systemic and hepatic metabolism. We induced NASH by pre-feeding C57BL/6J mice a diet rich in fat, fructose and cholesterol for 36 weeks. This was followed by 8 weeks of treatment with the receptor-specific agonists 1-GCG (20 μg/kg twice daily), 2-GLP1 (3 μg/kg twice daily) or 3-GIP (30 μg/kg twice daily), or the dual (1 + 2) or triple (1 + 2 + 3) combinations thereof. A dual GLP-1R/GCGR agonistic peptide, 4-dual-GLP1/GCGR (30 μg/kg twice daily), and liraglutide (100 μg/kg twice daily) were included as references. Whereas low-dose 1-GCG or 3-GIP alone did not influence body weight, liver lipids and histology, their combination with 2-GLP1 provided additional weight loss, reduction in liver triglycerides and improvement in histological disease activity score. Notably, 4-dual-GLP-1R/GCGR and the triple combination of selective mono-agonists led to a significantly stronger reduction in the histological non-alcoholic fatty liver disease activity score compared to high-dose liraglutide, at the same extent of body weight loss. GCGR and GIPR agonism provide additional, body weight-independent improvements on top of GLP-1R agonism in a murine model of manifest NASH with fibrosis. Show less

Cardiac myosin binding protein-C (cMyBP-C) phosphorylation is essential for normal heart function and protects the heart from ischemia-reperfusion (I/R) injury. It is known that protein kinase-A (PKA)-mediated phosphorylation of cMyBP-C prevents I/R-dependent proteolysis, whereas dephosphorylation of cMyBP-C at PKA sites correlates with its degradation. While sites on cMyBP-C associated with phosphorylation and proteolysis co-localize, the mechanisms that link cMyBP-C phosphorylation and proteolysis during cardioprotection are not well understood. Therefore, we aimed to determine if abrogation of cMyBP-C proteolysis in association with calpain, a calcium-activated protease, confers cardioprotection during I/R injury. Calpain is activated in both human ischemic heart samples and ischemic mouse myocardium where cMyBP-C is dephosphorylated and undergoes proteolysis. Moreover, cMyBP-C is a substrate for calpain proteolysis and cleaved by calpain at residues 272-TSLAGAGRR-280, a domain termed as the calpain-target site (CTS). Cardiac-specific transgenic (Tg) mice in which the CTS motif was ablated were bred into a cMyBP-C null background. These Tg mice were conclusively shown to possess a normal basal structure and function by analysis of histology, electron microscopy, immunofluorescence microscopy, Q-space MRI of tissue architecture, echocardiography, and hemodynamics. However, the genetic ablation of the CTS motif conferred resistance to calpain-mediated proteolysis of cMyBP-C. Following I/R injury, the loss of the CTS reduced infarct size compared to non-transgenic controls. Collectively, these findings demonstrate the physiological significance of calpain-targeted cMyBP-C proteolysis and provide a rationale for studying inhibition of calpain-mediated proteolysis of cMyBP-C as a therapeutic target for cardioprotection. Show less

CLN3 is a rare lysosomal storage disorder. The majority of the patients suffer from neurological degeneration in the first decade of life leading to death in the second or third decade. One of the first symptoms is a rapid visual decline from retinal degeneration. The aim of this study was to correlate the retinal changes in CLN3 as seen with spectral domain optical coherence tomography (SD-OCT) with functional data in patients in the first years after the subjective onset of ocular symptoms. Three unrelated children aged from 5.6 to 8.8 years, and with molecularly confirmed CLN3, underwent a comprehensive ophthalmological examination including visual acuity, fundus photography, fundus autofluorescence (FAF), electrophysiology (multifocal ERG), Goldmann visual fields, and SD-OCT. A predominant loss of the first and second neuron retinal layers progressing from the macula to the periphery was identifed. The retinal nerve fibre layer (RNFL) displayed gliosis and an irregular lining of the inner limiting membrane. Compared to the preferential reduction of photoreceptor layer thickness in other maculopathies with pan-retinal involvement, the thickness of the first and second neuron layers was reduced simultaneously in CLN3. Functional testing by multifocal ERG reflected the degenerative progress. Semiquantitative evaluation revealed a generally reduced FAF. This is the first detailed morphological evaluation of CLN3 patients in the first years after the subjective onset of ocular symptoms. CLN3 is characterized by an early degeneration predominant of the first and second neuron compared to other macular and generalized retinal dystrophies. Imaging is instrumental for early diagnosis and gene-directed molecular analysis of this fatal disorder. Show less

We conducted a genome-wide association study of essential tremor, a common movement disorder characterized mainly by a postural and kinetic tremor of the upper extremities. Twin and family history studies show a high heritability for essential tremor. The molecular genetic determinants of essential tremor are unknown. We included 2807 patients and 6441 controls of European descent in our two-stage genome-wide association study. The 59 most significantly disease-associated markers of the discovery stage were genotyped in the replication stage. After Bonferroni correction two markers, one (rs10937625) located in the serine/threonine kinase STK32B and one (rs17590046) in the transcriptional coactivator PPARGC1A were associated with essential tremor. Three markers (rs12764057, rs10822974, rs7903491) in the cell-adhesion molecule CTNNA3 were significant in the combined analysis of both stages. The expression of STK32B was increased in the cerebellar cortex of patients and expression quantitative trait loci database mining showed association between the protective minor allele of rs10937625 and reduced expression in cerebellar cortex. We found no expression differences related to disease status or marker genotype for the other two genes. Replication of two lead single nucleotide polymorphisms of previous small genome-wide association studies (rs3794087 in SLC1A2, rs9652490 in LINGO1) did not confirm the association with essential tremor. Show less

In metazoa, nuclear pore complexes (NPCs) are assembled from constituent nucleoporins by two distinct mechanisms: in the re-forming nuclear envelope at the end of mitosis and into the intact nuclear envelope during interphase. Here, we show that the nucleoporin Nup153 is required for NPC assembly during interphase but not during mitotic exit. It functions in interphasic NPC formation by binding directly to the inner nuclear membrane via an N-terminal amphipathic helix. This binding facilitates the recruitment of the Nup107-160 complex, a crucial structural component of the NPC, to assembly sites. Our work further suggests that the nuclear transport receptor transportin and the small GTPase Ran regulate the interaction of Nup153 with the membrane and, in this way, direct pore complex assembly to the nuclear envelope during interphase. Show less

Stimulation of the liver X receptor (LXR) is associated with anti-inflammatory and vascular-protective effects under hyperlipemic conditions. We examined whether LXR stimulation influences TNF-α-induced endothelial dysfunction under normolipemic conditions. Endothelium-dependent vasorelaxation of aortic rings was determined in an organ water bath. Human umbilical vein endothelial cells (HUVEC) were exposed to TNF-α (10 ng/ml) in the presence or absence of 5 μM of the LXR agonist T0901317 or GW3965 and changes in TNF-α-induced endothelial cell apoptosis, inflammation, oxidative stress, and NO metabolism were analyzed. T0901317 improved TNF-α-impaired endothelium-dependent relaxation of aortic rings in response to acetylcholine. T0901317 decreased the TNF-α-induced apoptosis and inflammation as indicated by a decrease in caspase 3/7 activity, VCAM-1 mRNA expression and subsequent mononuclear cell adhesion. Furthermore, T0901317 reduced the expression of the oxidative stress markers: AT1R, NOX4, and p22phox and normalized the TNF-α-induced NOX activity to basal levels. In line with the reduced AT1R expression, T0901317 impaired the Ang II responsiveness. T0901317 influenced NO metabolism as indicated by a decrease in TNF-α-upregulated arginase activity, a reversal of TNF-α-induced downregulation of argininosuccinate synthase mRNA expression and eNOS expression to basal levels and a raise in NO production. Furthermore, T0901317 decreased the TNF-α-induced superoxide and nitrotyrosine production, but did not upregulate the TNF-α-downregulated eNOS dimer/monomer ratio. Silencing of LXRβ, but not of LXRα, abrogated the anti-apoptotic effects of T0901317. We conclude that LXR agonism improves TNF-α-impaired endothelial function via its anti-apoptotic, anti-inflammatory, and anti-oxidative properties and its capacity to restore TNF-α-impaired NO bioavailability independent of its cholesterol-modulating effects. Show less

Phytosterol-enriched foods are increasingly marketed to lower cholesterol levels and atherosclerosis in the general population. Phytosterols reduce cholesterol absorption, but the molecular mechanism is controversial. We therefore investigated the phytosterol effects on cholesterol metabolism in human enterocyte, hepatocyte, and macrophage models relevant for sterol absorption, reverse transport, and excretion. Isomolar sitosterol (50 μmol/L) was less effectively taken up by enterocytes than cholesterol but suppressed apical cholesterol uptake by 50% (P < 0.01) and basolateral secretion by two-thirds (P < 0.01) whether added in micelles or ethanol or complexed to cyclodextrin. In contrast, enterocytes handled nanomolar (3)H-sitosterol similarly to cholesterol. Enterocytes selectively oxidized all sterols to 27-hydroxy- and 27-carboxy-sterols. Conversion rates were much lower for sitosterol (0.05 ± 0.02 nmol/mg protein) and campesterol (0.48 ± 0.10) compared with cholesterol (3.73 ± 0.60) (P < 0.001). 27-Hydroxycholesterol (27OH-C) activated liver-X-receptor alpha (LXRα) (P < 0.01) and stimulated ATP-binding cassette transporter (ABC) A1 expression (P < 0.001) and basolateral systemic cholesterol secretion from enterocytes (P < 0.05). In co-incubations, phytosterols inhibited 27OH-C generation by sterol 27-hydroxylase (P < 0.001) and reduced LXRα-mediated ABCA1 expression (P < 0.01) and basolateral systemic cholesterol secretion. In contrast, ABCG8 transcription and apical sterol resecretion was unchanged by LXRα activation in human enterocytes. Exogenous LXRα agonists reverted sterol selectivity and phytosterol cholesterol interaction. Due to constitutive apical expression of ABCG5/G8 and LXRα-enhanced basolateral expression of ABCA1 in enterocytes, interference of phytosterols with the generation of the dominating LXRα-agonist 27OH-C blocks the self-priming component of cholesterol absorption. This local LXRα antagonism of dietary phytosterols contributes to sterol selectivity and reduces fractional cholesterol absorption and preloading of nascent HDL with dietary cholesterol. Show less

Essential tremor (ET) and Parkinson's disease (PD) are the most common movement disorders and show clinical, genetic, and pathophysiological overlap. Single-nucleotide polymorphisms (SNPs) in the leucine-rich repeat (LRR) and immunoglobulin (Ig) domain-containing, Nogo receptor-interacting protein gene (LINGO1) are associated with ET. LINGO1 is overexpressed in the substantia nigra (SN) of PD patients and inhibition of LINGO1 confers neuroprotection in a rodent model of PD. In this study we test the hypothesis whether SNPs in the LINGO1 gene that are associated with ET are also associated with PD. Three large German case-control samples from Kiel, Lübeck, and Tübingen (total: 1,798 cases and 1,482 controls) were genotyped for the three LINGO1 SNPs associated with ET. Association was assessed using allele- and genotype-based tests in each of the three samples separately, in the combined sample, and in subsets of patients with early-onset PD (<50 years) and of patients with a positive family history of PD. Neither of the three samples alone nor the combined sample showed evidence for association between LINGO1 SNPs and PD. The allele-based test showed a trend toward nominal association for all three SNPs in the Kiel sample. The subsets with early-onset PD or a positive family history did also not reveal evidence for association. SNPs in the LINGO1 gene associated with ET could not be shown to be associated with PD in our study population, despite a postulated overlap between both diseases. Show less

Essential tremor (ET) is one of the most common movement disorders. Former association studies focussing on candidate genes in ET found a number of risk variants but most of them were not replicated. Recently, a genome-wide association study revealed two intronic sequence variants in the LINGO1 gene associated with ET. Here, we have confirmed association between sequence variants in the LINGO1 gene and the ET phenotype in independent German and French ET samples. The odds ratios for the identified intronic markers rs8030859 (P = 1.0x10(-4)), rs9652490 (P = 9.1x10(-4)), and rs11856808 (P = 3.6x10(-2)) were 1.72 (CI 1.31-2.26), 1.61 (CI 1.21-2.14), and 1.30 (CI 1.02-1.66), respectively, in our German sample. LINGO1 is an interesting candidate gene because it plays a key role in central nervous system biology, is selectively expressed in the nervous system, and is an inhibitor of oligodendrocyte differentiation and neuronal myelination. Our study gives further evidence that LINGO1 acts as a susceptibility gene for ET. Show less

Based on the oxidation hypothesis high doses of alpha-tocopherol have been advocated to prevent atherosclerosis, but clinical trials failed to demonstrate a benefit. As specific oxylipids activate PPARgamma and LXRalpha, master regulators of lipid metabolism and cholesterol exporters, we hypothesized, that high dose alpha-tocopherol might interfere with reverse cholesterol transport out of the vessel wall. Human THP-1 cells, a foam cell model, were preincubated with alpha-tocopherol or carrier before exposure to oxidized LDL, delipidated HDL or control buffer. Specific mRNAs were quantified by real-time RT-PCR, LXRalpha activation by a reporter gene assay and cellular cholesterol homeostasis by oxLDL and dHDL facilitated uptake and efflux assays. alpha-Tocopherol significantly reduced baseline expression and stimulation by oxLDL of LXRalpha activity, CD36, ABCA1, and ABCG1. alpha-Tocopherol also reversed the suppression of CD36 and ABCA1 by dHDL. Thus alpha-Tocopherol compromises cellular lipid scavenging and channelling of cholesterol into reverse transport out of the vessel wall. Show less