👤 Alessandra Galli

PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibition is a potent cholesterol-lowering strategy. This study examined the effects of PCSK9 monoclonal antibodies (mAbs) and high-intensity statins beyond low-density lipoprotein cholesterol reduction, which are not fully defined, particularly in patients with acute myocardial infarction (MI). Proteomic and lipidomic analyses were conducted on plasma from 265 patients with acute MI from the PACMAN-AMI (Effects of the PCSK9 Antibody Alirocumab on Coronary Atherosclerosis in Patients With Acute Myocardial Infarction) randomized, placebo-controlled PCSK9 mAb trial and 34 patients without MI with hyperlipidemia from the Vienna Lipid Clinic registry, also receiving PCSK9 mAbs. Discovery proteomics revealed changes in apolipoproteins and increased PCOLCE (procollagen C-endopeptidase enhancer 1) levels in both the PCSK9 mAb and placebo groups after MI. UK Biobank data confirmed PCOLCE and PCSK9 upregulation as associated with statin use. Hepatoma cell experiments demonstrated a dose-dependent PCOLCE induction on statin treatment. Compared with placebo (statins only), PCSK9 mAb therapy resulted in greater reductions in APOB (apolipoprotein B), APOE (apolipoprotein E), APOC2 (apolipoprotein C2), and APOC3 (apolipoprotein C3), as shown by targeted proteomics. Mediation analysis indicated that these changes were largely explained by low-density lipoprotein cholesterol lowering. Lipidomics identified more pronounced reductions in cholesteryl esters, ceramides, sphingomyelins, phosphatidylcholines, triglycerides, and diglycerides in PCSK9 mAb-treated patients with MI. Results were largely consistent in patients without MI. However, levels of LPA (apolipoprotein[a]), the characteristic protein component of lipoprotein(a), remained unchanged in PCSK9 mAb-treated patients with MI, since a rise of LPA was observed in the placebo group post-MI. Most apolipoprotein changes after PCSK9 mAb therapy following MI were mediated by low-density lipoprotein cholesterol lowering. Statin use is associated with increased circulating PCOLCE, with hepatoma cell experiments supporting a predominant hepatic origin. Combining PCSK9 mAbs with high-intensity statins mitigates post-MI increases in lipoprotein(a). URL: https://www.clinicaltrials.gov; Unique identifier: NCT03067844. Show less

Familial hypercholesterolaemia (FH) is a severely underdiagnosed, inherited disease, causing dyslipidaemia and premature atherosclerotic cardiovascular disease. In order to facilitate screening in a broad clinical spectrum, we aimed to analyse the current yield of routine genetic diagnostics for FH and to evaluate the performance of the Dutch Lipid Clinic Network Score (DLCNS) compared to a single value, the off-treatment LDL-cholesterol exceeding 190 mg/dL. We investigated all patients that underwent molecular genotyping routinely performed for FH over a 4-year period in two Austrian specialist lipid clinics. Variants reported in FH-causing genes including LDLR, APOB, PCSK9, LDLRAP, and APOE were collected and classified. For clinical classification, the DLCNS was calculated retrospectively and compared to the original scores documented in patient charts. Additionally, a literature review on comparisons of DLCNS to LDL-C was performed. Of 469 patients tested, 21.3% had a disease-causing variant. A median of 3 out of 8 (excluding genotyping results and LDL-C) DLCNS criteria were unavailable. DLCNS was documented in 48% of cases, with significant discrepancies compared to retrospective scoring (P < 0.001). DLCNS did not outperform off-treatment LDL-C alone (Δ = 0.006; P = 0.660), analogously to several reports identified in the literature. A single cut-off of 190 mg/dL LDL-C compared to DLCNS ≥ 6 showed excellent sensitivity (84.9% vs. 53.8%) and acceptable specificity (39.0% vs. 84.1%). Missing criteria and severe discrepancies observed between retrospective and on-site scoring by treating physicians were highly prevalent, confirming limited utility of DLCNS in clinical routine and warranting a single off-treatment LDL-C cut-off of 190 mg/dL for enhanced index-case identification. Show less

Autophagy has been implicated in various cellular processes, including non-conventional secretion. Our previous findings suggest that ATP is loaded into amphisomes and secreted upon autophagy stimulation at focal adhesion sites in a VAMP7-dependent manner. Here, we demonstrate that the knockout (KO) of VAMP7, along with its partners RAB21 and its guanine nucleotide exchange factor (GEF) VARP, inhibits ATP release, indicating a key role for this pathway in amphisome secretion. Constitutively inactive RAB21 also inhibited ATP secretion. RAB21 overexpression rescued starvation-induced ATP secretion in RAB21 KO, but not in VAMP7 or VARP KO cells. RAB21-LC3-positive vesicles redistributed to the cell periphery upon starvation. KO cells and overexpression experiments showed that RAB21 plays a positive role in autophagosome biogenesis, particularly in controlling the number of LC3-II- and DFCP1-positive structures upon starvation, suggesting a role in the early steps of autophagosome formation. Accordingly, VARP partially colocalized with LC3 upon starvation. Together, these findings identify a novel role for RAB21 in regulating autophagic ATP secretion likely in amphisome biogenesis and their localization in the cell periphery. Show less

Simultaneous activation of the incretin G-protein-coupled receptors (GPCRs) via unimolecular dual-receptor agonists (UDRA) has emerged as a new therapeutic approach for type 2 diabetes. Recent studies also advocate triple agonism with molecules also capable of binding the glucagon receptor. In this scoping review, we discuss the cellular mechanisms of action (MOA) underlying the actions of these novel and therapeutically important classes of peptide receptor agonists. Clinical efficacy studies of several UDRAs have demonstrated favorable results both as monotherapies and when combined with approved hypoglycemics. Although the additive insulinotropic effects of dual glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic peptide receptor (GIPR) agonism were anticipated based on the known actions of either glucagon-like peptide-1 (GLP-1) or glucose-dependent insulinotropic peptide (GIP) alone, the additional benefits from GCGR were largely unexpected. Whether additional synergistic or antagonistic interactions among these G-protein receptor signaling pathways arise from simultaneous stimulation is not known. The signaling pathways affected by dual- and tri-agonism require more trenchant investigation before a comprehensive understanding of the cellular MOA. This knowledge will be essential for understanding the chronic efficacy and safety of these treatments. Show less

The recent obesity epidemic in children also showed an increase in the prevalence of hypertension. As blood pressure (BP) is associated with (long-chain) polyunsaturated fatty acids (LC PUFA), genetic variation in desaturase enzymes being involved in the synthesis of LC PUFA may be associated with BP. This study aimed to investigate the direct effects (independent of mediating variables) and indirect effects (mediated through intermediate variables) of a common variant in the FADS1 gene, rs174546, known to affect delta-5 desaturase (D5D) activity on PUFA level, body mass index (BMI) and BP. A subsample of the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) baseline survey including 520 children aged 2 to <10 years from six European countries was included. The association between rs174546 (TShow less

The compartmental organization of eukaryotic cells is maintained dynamically by vesicular trafficking. SNARE proteins play a crucial role in intracellular membrane fusion and need to be targeted to their proper donor or acceptor membrane. The molecular mechanisms that allow for the secretory vesicles carrying the v-SNARE TI-VAMP/VAMP7 to leave the cell center, load onto microtubules, and reach the periphery to mediate exocytosis are largely unknown. Here, we show that the TI-VAMP/VAMP7 partner Varp, a Rab21 guanine nucleotide exchange factor, interacts with GolginA4 and the kinesin 1 Kif5A. Activated Rab21-GTP in turn binds to MACF1, an actin and microtubule regulator, which is itself a partner of GolginA4. These components are required for directed movement of TI-VAMP/VAMP7 vesicles from the cell center to the cell periphery. The molecular mechanisms uncovered here suggest an integrated view of the transport of vesicles carrying a specific v-SNARE toward the cell surface. Show less

The vesicular soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) tetanus neurotoxin-insensitive vesicle-associated membrane protein (TI-VAMP/VAMP7) was previously shown to mediate an exocytic pathway involved in neurite growth, but its regulation is still largely unknown. Here we show that TI-VAMP interacts with the Vps9 domain and ankyrin-repeat-containing protein (Varp), a guanine nucleotide exchange factor (GEF) of the small GTPase Rab21, through a specific domain herein called the interacting domain (ID). Varp, TI-VAMP and Rab21 co-localize in the perinuclear region of differentiating hippocampal neurons and transiently in transport vesicles in the shaft of neurites. Silencing the expression of Varp by RNA interference or expressing ID or a form of Varp deprived of its Vps9 domain impairs neurite growth. Furthermore, the mutant form of Rab21, defective in GTP hydrolysis, enhances neurite growth. We conclude that Varp is a positive regulator of neurite growth through both its GEF activity and its interaction with TI-VAMP. Show less

The present study aims at evaluating the influence of genetic polymorphisms on antiretroviral therapy (ART)-associated lipodystrophy. We included in the study 255 ICoNA. patients and we assessed the distribution of Fas -670 AG polymorphism, ApoC3 -455 CT and -482 CT polymorphisms, C161T silent substitution in the PPAR gamma gene, the Adrenergic beta3 Receptor (ARbeta3) codon 64 TC variant, and two polymorphisms in the Adrenergic beta2 Receptor (ARbeta2) codon 16 AG and codon 27 CG. Crude rates of lipoatrophy and fat accumulation and adjusted relative rates were calculated using Poisson regression. In a multivariate model after adjusting for gender, HIV exposure, age, current viral load, hepatitis C virus (HCV) serology, nucleoside reverse-transcriptase inhibitor (NRTI) pair/'third drugs' currently used, months of pre-highly active antiretroviral therapy (HAART) exposures to NRTI, the following genotypes resulted protective against lipoatrophy: ApoC3 -455 CC genotype [adjusted relative risks (ARR) 0.2, 95% confidence interval (CI) 0.046-0.91 vs CT/TT, P = 0.037], ARbeta3 codon 64 TT genotype (ARR 0.39, 95% CI 0.14-1.06 vs TC/CC, P = 0.066), and Fas -670 GG genotype (ARR 0.51, 95% CI 0.26-1.01 vs AG/AA, P = 0.053). With regard to fat accumulation, in the multivariate model, the ARbeta2 codon 27 CC genotype resulted protective (ARR 0.21, 95% CI 0.08-0.51 vs CG/GG, P = 0.0006), whereas the ARbeta2 codon 16 AA genotype resulted associated with higher risk (ARR 3.72, 95% CI 1.58-8.76 vs AG/GG, P = 0.0026). Our study suggests that genetic polymorphisms of genes involved in apoptosis and adipocyte metabolism are significantly related to ART associated lipodystrophy. Particularly, we evidenced a role for ApoC3 -455 in lipoatrophy and for the two variants of ARbeta2 in fat accumulation. Show less