Functional Characterization of p.(Arg160Gln) PCSK9 Variant Accidentally Found in a Hypercholesterolemic Subject.

Familial hypercholesterolaemia (FH) is an autosomal dominant dyslipidaemia, characterised by elevated LDL cholesterol (LDL-C) levels in the blood. Three main genes are involved in FH diagnosis: LDL receptor (LDLr), Apolipoprotein B (APOB) and Protein convertase subtilisin/kexin type 9 (PCSK9) with genetic mutations that led to reduced plasma LDL-C clearance. To date, several PCSK9 gain-of-function (GOF) variants causing FH have been described based on their increased ability to degrade LDLr. On the other hand, mutations that reduce the activity of PCSK9 on LDLr degradation have been described as loss-of-function (LOF) variants. It is therefore important to functionally characterise PCSK9 variants in order to support the genetic diagnosis of FH. The aim of this work is to functionally characterise the p.(Arg160Gln) PCSK9 variant found in a subject suspected to have FH. Different techniques have been combined to determine efficiency of the autocatalytic cleavage, protein expression, effect of the variant on LDLr activity and affinity of the PCSK9 variant for the LDLr. Expression and processing of the p.(Arg160Gln) variant had a result similar to that of WT PCSK9. The effect of p.(Arg160Gln) PCSK9 on LDLr activity is lower than WT PCSK9, with higher values of LDL internalisation (13%) and p.(Arg160Gln) PCSK9 affinity for the LDLr is lower than WT, EC50 8.6 ± 0.8 and 25.9 ± 0.7, respectively. The p.(Arg160Gln) PCSK9 variant is a LOF PCSK9 whose loss of activity is caused by a displacement of the PCSK9 P' helix, which reduces the stability of the LDLr-PCSK9 complex.

Search for familial hypercholesterolemia patients in an Italian community: A real-life retrospective study.

BACKGROUND AND AIMS: Familial hypercholesterolemia (FH) is a common inherited disorder of low-density lipoprotein (LDL) catabolism that causes elevated LDL-cholesterol (LDL-C) and premature atherosclerotic cardiovascular disease (ASCVD). Despite the availability of effective treatments, FH remains underdiagnosed and undertreated. The aims of the study were to identify putative FH subjects using data from laboratory and cardiology databases, genetically characterize suspected FH patients referred to the Lipid Clinic and monitor attainment of treatment goals in identified patients. METHODS AND RESULTS: We retrieved the electronic health records of 221,644 individuals referred to laboratory for routine assessment and of 583 ASCVD patients (age ≤65) who underwent percutaneous transluminal coronary angioplasty (PTCA). We monitored the lipid profiles of subjects with LDL-C ≥ 250 mg/dl identified by laboratory survey (LS-P), PTCA patients and patients from the Lipid Clinic (LC-P). The laboratory survey identified 1.46% of subjects with LDL-C ≥ 190 mg/dl and 0.08% with LDL-C ≥ 250 mg/dl. Probable/definite FH was suspected in 3% of PTCA patients. Molecularly-confirmed FH was found in 44% of LC-P subjects. Five new LDLR mutations were identified. The 50% LDL-C reduction target was achieved by 70.6% of LC-P patients. Only 18.5% of PTCA patients reached the LDL-C < 55 mg/dl target. CONCLUSION: By using a combined approach based on laboratory lipid profiles, documented ASCVD and Lipid Clinic data, we were able to identify subjects with a high probability of being FH. Attainment of LDL-C goals was largely suboptimal. Efforts are needed to improve FH detection and achievement of lipid targets.

The association between clinical laboratory data and chest CT findings explains disease severity in a large Italian cohort of COVID-19 patients.

BACKGROUND: Laboratory data and computed tomography (CT) have been used during the COVID-19 pandemic, mainly to determine patient prognosis and guide clinical management. The aim of this study was to evaluate the association between CT findings and laboratory data in a cohort of COVID-19 patients. METHODS: This was an observational cross-sectional study including consecutive patients presenting to the Reggio Emilia (Italy) province emergency rooms for suspected COVID-19 for one month during the outbreak peak, who underwent chest CT scan and laboratory testing at presentation and resulted positive for SARS-CoV-2. RESULTS: Included were 866 patients. Total leukocytes, neutrophils, C-reactive protein (CRP), creatinine, AST, ALT and LDH increase with worsening parenchymal involvement; an increase in platelets was appreciable with the highest burden of lung involvement. A decrease in lymphocyte counts paralleled worsening parenchymal extension, along with reduced arterial oxygen partial pressure and saturation. After correcting for parenchymal extension, ground-glass opacities were associated with reduced platelets and increased procalcitonin, consolidation with increased CRP and reduced oxygen saturation. CONCLUSIONS: Pulmonary lesions induced by SARS-CoV-2 infection were associated with raised inflammatory response, impaired gas exchange and end-organ damage. These data suggest that lung lesions probably exert a central role in COVID-19 pathogenesis and clinical presentation.

Serum Copeptin levels in the emergency department predict major clinical outcomes in adult trauma patients.

BACKGROUND: Early prognostication in trauma patients is challenging, but particularly important. We wanted to explore the ability of copeptin, the C-terminal fragment of arginine vasopressin, to identify major trauma, defined as Injury Severity Score (ISS) > 15, in a heterogeneous cohort of trauma patients and to compare its performances with lactate. We also evaluated copeptin performance in predicting other clinical outcomes: mortality, hospital admission, blood transfusion, emergency surgery, and Intensive Care Unit (ICU) admission. METHODS: This single center, pragmatic, prospective observational study was conducted at Arcispedale Santa Maria Nuova, a level II trauma center in Reggio Emilia, Italy. Copeptin determination was obtained on Emergency Department (ED) arrival, together with venous lactate. Different outcomes were measured including ISS, Revised Trauma Score (RTS), hospital and ICU admission, blood transfusion, emergency surgery, and mortality. RESULTS: One hundred and twenty five adult trauma patients admitted to the ED between June 2017 and March 2018. Copeptin showed a good ability to identify patients with ISS > 15 (AUC 0.819). Similar good performances were recorded also in predicting other outcomes. Copeptin was significantly superior to lactate in identifying patients with ISS > 15 (P 0.0015), and in predicting hospital admission (P 0.0002) and blood transfusion (P 0.016). Comparable results were observed in a subgroup of patients with RTS 7.84. CONCLUSIONS: In a heterogeneous group of trauma patients, a single copeptin determination at the time of ED admission proved to be an accurate biomarker, statistically superior to lactate for the identification of major trauma, hospital admission, and blood transfusion, while no statistical difference was observed for ICU admission and emergency surgery. These results, if confirmed, may support a role for copeptin during early management of trauma patients.

Red blood cells metabolome changes upon treatment with different X-ray irradiation doses.

The upholding of red blood cells (RBC) quality and the removal of leukocytes are two essential issues in transfusion therapy. Leukodepletion provides optimum results, nonetheless there are cases where irradiation is recommended for some groups of hematological patients such as the ones with chronic graft-vs-host disease, congenital cellular immunodeficiency, and hematopoietic stem cell transplant recipients. The European guidelines suggest irradiation doses from 25 to 50 Gray (Gγ). We evaluated the effect of different prescribed doses (15 to 50 Gγ) of X-ray irradiation on fresh leukodepleted RBCs bags using a novel protocol that provides a controlled irradiation. Biochemical assays integrated with RBCs metabolome profile, assessed by nuclear magnetic resonance spectroscopy, were performed on RBC units supernatant, during 14 days storage. Metabolome analysis evidenced a direct correlation between concentration increase of three metabolites, glycine, glutamine and creatine, and irradiation dose. Higher doses (35 and 50 Gγ) effect on RBC mean corpuscular volume, hemolysis, and ammonia concentration are considerable after 7 and 14 days of storage. Our data show that irradiation with 50 Gγ should be avoided and we suggest that 35 Gγ should be the upper limit. Moreover, we suggest for leukodepleted RBCs units the irradiation with the prescribed dose of 15 Gγ, value at center of bag, and ranging between 13.35-15 Gγ, measured over the entire bag volume, may guarantee the same benefits of a 25 Gγ dose assuring, in addition, a better quality of RBCs.

The study of familial hypercholesterolemia in Italy: A narrative review.

In this review we outline our experience in the clinical and molecular diagnosis of familial hypercholesterolemia (FH), built up over more than three decades. We started our work by selecting FH patients on the basis of stringent clinical criteria, including extensive family studies. In most patients we confirmed the clinical diagnosis by showing a reduced LDLR activity in skin fibroblasts. After the isolation of LDLR cDNA and the characterization of the corresponding gene by the Dallas group, we started a systematic molecular investigation of our patients first using Southern blotting, and, subsequently Sanger sequencing. Up to now we have been able to identify 260 mutations of LDLR gene in more than 1000 genotyped FH patients, including 68 homozygotes. During this survey we identified 13 mutation clusters located in different geographical districts, which gave us the chance to compare the phenotype of patients carrying the most common mutations. We also found that mutations in APOB and PCSK9 genes were a rare cause of FH in our cohort. Despite our efforts, we failed to identify mutations in candidate genes in ∼20% of cases of definite FH. An exome-wide study, conducted within the context of an international collaboration, excluded the presence of other major genes in our unexplained FH cases. Recently, we have adopted sequencing technology of the next generation (NGS) with the parallel sequencing of a panel of FH targeted genes as a way of obtaining a more comprehensive picture of the gene variants potentially involved in the disease.

Spectrum of mutations and phenotypic expression in patients with autosomal dominant hypercholesterolemia identified in Italy.

OBJECTIVE: To determine the spectrum of gene mutations and the genotype-phenotype correlations in patients with Autosomal Dominant Hypercholesterolemia (ADH) identified in Italy. METHODS: The resequencing of LDLR, PCSK9 genes and a selected region of APOB gene were conducted in 1018 index subjects clinically heterozygous ADH and in 52 patients clinically homozygous ADH. The analysis was also extended to 1008 family members of mutation positive subjects. RESULTS: Mutations were detected in 832 individuals: 97.4% with LDLR mutations, 2.2% with APOB mutations and 0.36% with PCSK9 mutations. Among the patients with homozygous ADH, 51 were carriers of LDLR mutations and one was an LDLR/PCSK9 double heterozygote. We identified 237 LDLR mutations (45 not previously reported), 4 APOB and 3 PCSK9 mutations. The phenotypic characterization of 1769 LDLR mutation carriers (ADH-1) revealed that in both sexes independent predictors of the presence of tendon xanthomas were age, the quintiles of LDL cholesterol, the presence of coronary heart disease (CHD) and of receptor negative mutations. Independent predictors of CHD were male gender, age, the presence of arterial hypertension, smoking, tendon xanthomas, the scalar increase of LDL cholesterol and the scalar decrease of HDL cholesterol. We identified 13 LDLR mutation clusters, which allowed us to compare the phenotypic impact of different mutations. The LDL cholesterol raising potential of these mutations was found to vary over a wide range. CONCLUSIONS: This study confirms the genetic and allelic heterogeneity of ADH and underscores that the variability in phenotypic expression of ADH-1 is greatly affected by the type of LDLR mutation.

Lysosomal lipase deficiency: molecular characterization of eleven patients with Wolman or cholesteryl ester storage disease.

Wolman Disease (WD) and cholesteryl ester storage disease (CESD) represent two distinct phenotypes of the same recessive disorder caused by the complete or partial deficiency of lysosomal acidic lipase (LAL), respectively. LAL, encoded by the LIPA gene, hydrolyzes cholesteryl esters derived from cell internalization of plasma lipoproteins. WD is a rapidly progressive and lethal disease characterized by intestinal malabsorption, hepatic and adrenal failure. CESD is characterized by hepatic fibrosis, hyperlipidemia and accelerated atherosclerosis. Aim of the study was the identification of LIPA mutations in three WD and eight CESD patients. The WD patients, all deceased before the first year of age, were homozygous for two novel mutations (c.299+1G>A and c.419G>A) or a mutation (c.796G>T) previously reported as compound heterozygosity in a CESD patient. The two mutations (c.419G>A and c.796G>T) resulting in truncated proteins (p.W140* and p.G266*) and the splicing mutation (c.229+1G>A) were associated with undetectable levels of LIPA mRNA in fibroblasts. All eight CESD patients carried the common mutation c.894G>A known to result not only in a major non-functional transcript with the skipping of exon 8 (p.S275_Q298del), but also in a minor normally spliced transcript producing 5-10% residual LAL activity. The c.894G>A mutation was found in homozygosity in four patients and, as compound heterozygosity, in association with a known (p.H295Y and p.G342R) or a novel (p.W140*) mutation in four other CESD patients. Segregation analysis performed in all patients harboring c.895G>A showed its occurrence on the same haplotype suggesting a common founder ancestor. The other WD and CESD mutations were associated with different haplotypes.

A novel mutation of the apolipoprotein A-I gene in a family with familial combined hyperlipidemia.

We report a large family in which four members showed a plasma lipid profile consistent with the clinical diagnosis of familial combined hyperlipidemia (FCHL). One of these patients was found to have markedly reduced HDL cholesterol (HDL-C) (0.72 mmol/l) and Apo A-I (72 mg/dl) levels, a condition suggestive of the presence of a mutation in one of the HDL-related genes. The analysis of APOA1 gene revealed that this patient was heterozygous for a cytosine insertion in exon 3 (c.49-50 ins C), resulting in a frame-shift and premature stop codon at position 26 of pro-Apo A-I (Q17PFsX10). This novel mutation, which prevents the synthesis of Apo A-I, was also found in four family members, including three siblings and the daughter of the proband. Carriers of Apo A-I mutation had significantly lower HDL-C and Apo A-I than non-carriers family members (0.77+/-0.15 mmol/l vs. 1.15+/-0.20 mmol/l, P<0.005; 71.4+/-9.1mg/dl vs. 134.0+/-14.7 mg/dl, P<0.005, respectively). Two of the APOA1 mutation carriers, who were also heavy smokers, had fibrous plaques in the carotid arteries causing mild stenosis (20%). The intimal-media thickness in the two other adult carriers was within the normal range. The other non-carriers family members with FCHL had either overt vascular disease or carotid atherosclerosis at ultrasound examination. This observation suggests that the low HDL-C/low Apo A-I phenotype may result from a genetic defect directly affecting HDL metabolism, even in the context of a dyslipidemia which, like FCHL, is associated with low plasma HDL-C.

Effect of ezetimibe coadministered with statins in genotype-confirmed heterozygous FH patients.

We investigated the effect of statins and statins plus ezetimibe in 65 FH heterozygotes carrying LDLR-defective or LDLR-negative mutations as well as the effect of ezetimibe monotherapy in 50 hypercholesterolemic (HCH) patients intolerant to statins. PCSK9 and NPC1L1 genes were analysed to assess the role of genetic variants in response to therapy. In FH patients combined therapy reduced LDL-C by 57%, irrespective of the type of LDLR mutation. The additional decrease of plasma LDL-C induced by ezetimibe showed wide inter-individual variability (from -39% to -4.7%) and was negatively correlated with percent LDL-C decrease due to statin alone (r=-0.713, P<0.001). The variable response to statins was not due to PCSK9 gene variants associated with statin hyper-sensitivity. The highest response to ezetimibe was observed in a carrier of R174H substitution in NPC1L1, which had been found to be associated with high cholesterol absorption. In HCH patients, ezetimibe monotherapy induced a variable decrease of plasma LDL-C (from -47.7% to -13.4%). To investigate this variability, we sequenced NPC1L1 gene in patients with the highest and the lowest response to ezetimibe. This analysis showed a higher prevalence of the G allele of the c.816 C>G polymorphism (L272L) in hyper-responders, an observation confirmed also in FH patients hyper-responders to ezetimibe. In both FH and HCH patients, the G allele carriers tended to have a higher LDL-C reduction in response to ezetimibe. These observations suggest that in FH heterozygotes LDL-C reduction following combined therapy reflects a complex interplay between hepatic synthesis and intestinal absorption of cholesterol.