Mutant Apo Research Articles

Molecular simulation unravels the amyloidogenic misfolding of nascent ApoA1 protein, driven by deleterious point mutations occurring in between 170–178 hotspot region

Protein ApoA1 is extensively studied for its role in lipid metabolism. Its seedy dark side of amyloid formulation remains relatively understudied yet. Due to genetic mutations, the protein pathologically misshapes into its amyloid form that gets accumulated in various organs, including the heart. To contrive effective therapeutics against this debilitating congenital disorder, it is imperative to comprehend the structural ramifications induced by mutations in APoA1’s dynamic conformation. Till now, several point mutations have been implicated in ApoA1’s amyloidosis, although only a handful has been examined considerably. Especially, the single nucleotide polymorphisms (SNPs) that occur in-between 170–178 mutation hotspot site of APoA1 needs to be investigated, since most of them are culpable of amyloid deposition in the heart. To that effect, in the present study, we have computationally quantified and studied the ApoA1’s biomolecular modifications fostered by SNPs in the 170–178 mutation hotspot. Findings from discrete molecular dynamics simulation studies indicate that the SNPs have noticeably steered the ApoA1’s behaviour from its native structural dynamics. Analysis of protein’s secondary structural changes exhibits a considerable change upon mutations. Further, subjecting the protein structures to simulated thermal denaturation shows increased resistance to denaturation among mutants when compared to native. Further, normal mode analysis of protein’s dynamic motion also shows discrepancy in its dynamic structural change upon SNP. These structural digressions induced by SNPs can very well be the biomolecular incendiary that drives ApoA1 into its amyloidogenesis. And, understanding these structural modifications initiates a better understanding of SNP’s amyloidogenic pathology on APoA1. Communicated by Ramaswamy H. Sarma.

Lipoprotein glomerulopathy associated with the Osaka/Kurashiki APOE variant: two cases identified in Latin America

BackgroundLipoprotein glomerulopathy (LPG) is a rare autosomal dominant disease caused by mutations in APOE, the gene which encodes apolipoprotein E. LPG mainly affects Asian individuals, however occasional cases have also been described in Americans and Europeans. Herein we report two unrelated Brazilian patients with LPG in whom genetic analyses revealed the APOE-Osaka/Kurashiki variant.Case presentation - case 1A 29-year-old Caucasian male sought medical attention with complaints of face swelling and foamy urine for the last 3 months. He denied a family history of kidney disease, consanguinity, or Asian ancestry. His tests showed proteinuria of 12.5 g/24 h, hematuria, serum creatinine 0.94 mg/dL, albumin 2.3 g/dl, total cholesterol 284 mg/dL, LDL 200 mg/dL, triglycerides 175 mg/dL, and negative screening for secondary causes of glomerulopathy. A kidney biopsy revealed intraluminal, laminated deposits of hyaline material in glomerular capillaries consistent with lipoprotein thrombi. These findings were confirmed by electron microscopy, establishing the diagnosis of LPG. His apolipoprotein E serum level was 72 mg/dL and genetic analysis revealed the APOE pathogenic variant c.527G > C, p.Arg176Pro in heterozygosis, known as the Osaka/Kurashiki mutation and positioned nearby the LDL receptor binding site.Case 2A 34-year-old Caucasian man sought medical assessment for renal dysfunction and hypertension. He reported intermittent episodes of lower-limb edema for 3 years and a family history of kidney disease, but denied Asian ancestry. Laboratorial tests showed BUN 99 mg/dL, creatinine 10.7 mg/dL, total cholesterol 155 mg/dL, LDL 79 mg/dL, triglycerides 277 mg/dL, albumin 3.1 g/dL, proteinuria 2.7 g/24 h, and negative screening for secondary causes of glomerulopathy. His kidney biopsy was consistent with advanced chronic nephropathy secondary to LPG. A genetic analysis also revealed the Osaka/Kurashiki variant. He was transplanted a year ago, displaying no signs of disease relapse.ConclusionWe report two unrelated cases of Brazilian patients with a diagnosis of lipoprotein glomerulopathy whose genetic assessment identified the APOE-Osaka/Kurashiki pathogenic variant, previously only described in eastern Asians. While this is the second report of LPG in Latin America, the identification of two unrelated cases by our medical team raises the possibility that LPG may be less rare in this part of the world than currently thought, and should definitely be considered when nephrotic syndrome is associated with suggestive kidney biopsy findings.

Expression of e4 Mutant APOE Gene in a select South Indian Population Indicates Relation to Coronary Artery Disease

Expression of e4 Mutant APOE Gene in a select South Indian Population Indicates Relation to Coronary Artery Disease

Expression of e4 Mutant APOE Gene in a select South Indian Population Indicates Relation to Coronary Artery Disease

Expression of e4 Mutant APOE Gene in a select South Indian Population Indicates Relation to Coronary Artery Disease

Characterization of Lipid Metabolism and Atherosclerotic Phenotypes in Novel Humanized ApoE Knockin Rats

Apolipoprotein E (ApoE) is one of the essential plasma apolipoproteins involved majorly in lipids’ metabolism. Human ApoE has three isoforms (E2, E3, and E4) differing by one or two amino acids. E3 is the most common one with a population allelic frequency of 78% and considered normal. E2 (7%) is associated with genetic disorder type III hyperlipoproteinemia. E4 (15%) is the major susceptibility gene related to the onset of Alzheimer's disease (AD) and cardiovascular diseases (CVDs). Gene modified mice carrying a mutant ApoE gene or different ApoE isoforms, such as ApoE knockout (ApoE KO) mouse and humanized ApoE knockin (hApoE KI) mice, provide a series of beneficial mouse models in the studies of atherosclerosis, hyperlipidemia, and AD. However, alternative animal models are necessary to investigate the roles and underlying mechanisms of ApoE in human diseases. Recently, the novel hApoE KI rat models created by Envigo RMS, Saint Louis, MO (preciously named Horizon Discovery and SAGE Labs respectively) by replacing endogenous rat ApoE with human ApoE2, E3, or E4 allele are available. Hypothesis The hApoE KI rats could recapitulate the diversities of metabolic phenotypes in human carrying polymorphic ApoE proteins, and will be ideal animal models to study the roles of ApoE proteins. Methods We examed the body weight, serum lipid levels, the mass of fat tissue, and vascular atherosclerotic lesions of these hApoE rat models in comparison to wide-type Sprague Dawley (WT) and ApoE KO rats, as well as the metabolic changes, death rate, and development of vascular atherosclerosis of these rats with 4-months atherogenic Paigen diet (PD) (40 kcal% Fat, 1.25% Cholesterol, 0.5% Cholic Acid). Results We investigate the body weight starting from week seven till month six, and found that all the hApoE KI and ApoE KO rats had a lower body weight than WT at the corresponding age. The hApoE2 KI rats showed lowest body weight. At six months (P6m), all hApoE KI and KO rats had lower anti-atherogenic lipoprotein HDL. The total cholesterol (TC), total triacylglycerol (TG), and LDL/VLDL of hApoE2 KI rats were higher than those of WT, hApoE3 KI and hApoE4 KI rats. ApoE KO rats also exhibited elevated total cholesterol and LDL/VLDL, but not total triacylglycerol. Surprisingly, the mass of white fat was less in hApoE2 KI rats. No obvious aortic plaques were identified in the en face aortas stained by Oil Red O of all normal diet-fed hApoE KI and ApoE KO rats at P6m. A mild atherosclerotic lesion was detected in frozen section of hApoE2 KI and ApoE KO aortic roots. After challenged with the PD, hApoE2 KI and ApoE KO rats died within two and half weeks. Causes of death were different: hApoE2 KI rats might be due to fat embolism in big vessels and heart chambers; ApoE KO rats might be caused by massive pulmonary alveolar hydrops (accompanying considerable lipid-laden macrophages accumulated in the lung). Thicker walls of small vessels in lung and heart, as well as necrosis of cardiomyocytes, were demonstrated in hApoE4 KI rats after four months PD. Conclusion hApoE2 rats develop hyperlipoproteinemia but are not a suitable animal model for the study of atherosclerosis. With the assistance of a PD challenge, hApoE4 KI rats could be a good model for the analysis of CVDs.

High-Density Lipoproteins and the Kidney.

Dyslipidemia is a typical trait of patients with chronic kidney disease (CKD) and it is typically characterized by reduced high-density lipoprotein (HDL)-cholesterol(c) levels. The low HDL-c concentration is the only lipid alteration associated with the progression of renal disease in mild-to-moderate CKD patients. Plasma HDL levels are not only reduced but also characterized by alterations in composition and structure, which are responsible for the loss of atheroprotective functions, like the ability to promote cholesterol efflux from peripheral cells and antioxidant and anti-inflammatory proprieties. The interconnection between HDL and renal function is confirmed by the fact that genetic HDL defects can lead to kidney disease; in fact, mutations in apoA-I, apoE, apoL, and lecithin–cholesterol acyltransferase (LCAT) are associated with the development of renal damage. Genetic LCAT deficiency is the most emblematic case and represents a unique tool to evaluate the impact of alterations in the HDL system on the progression of renal disease. Lipid abnormalities detected in LCAT-deficient carriers mirror the ones observed in CKD patients, which indeed present an acquired LCAT deficiency. In this context, circulating LCAT levels predict CKD progression in individuals at early stages of renal dysfunction and in the general population. This review summarizes the main alterations of HDL in CKD, focusing on the latest update of acquired and genetic LCAT defects associated with the progression of renal disease.

Lipoprotein glomerulopathy induced by ApoE Kyoto mutation in ApoE-deficient mice

BackgroundLipoprotein glomerulopathy (LPG) is a rare autosomal dominant kidney disease that is most commonly caused by mutations in ApoE Kyoto (p.R43C) and ApoE Sendai (p.R163P). Differences in phenotype among the various ApoE mutations have been suggested, but the pathogenic role of ApoE Kyoto has not been validated in an animal model. This study intended to establish an ApoE Kyoto murine model and to further compare the pathologic differences between ApoE Kyoto and ApoE Sendai.MethodMale ApoE-deficient mice, 3 months of age, were divided into five groups, including the AD-ApoE Sendai, AD-ApoE Kyoto, AD-ApoE3, AD-eGFP, and ApoE (−/−) groups. The first four groups received recombinant adenovirus that contained the entire coding regions of the human ApoE Sendai and ApoE Kyoto, apoE3, and eGFP genes, respectively. Fasting blood and urine samples were collected at multiple time points. Lipid profiles and urine albumin–creatinine ratio were measured. Renal and aortic histopathologic alterations were analyzed.ResultsAfter virus injection, plasma human ApoE was detected and rapidly reached the maximum level at 4–6 days in the AD-ApoE Kyoto and AD-ApoE Sendai groups (17.4 ± 3.1 µg/mL vs.: 22.2 ± 4.5 µg/mL, respectively) and at 2 days in the AD-ApoE3 group (38.4 µg/mL). The serum total cholesterol decreased by 63%, 65%, and 73% in the AD-ApoE Kyoto, AD-ApoE Sendai and AD-ApoE3 groups, respectively. There were no significant changes in serum triglyceride and urinary albumin–creatinine ratio among the five groups. Typical lipoprotein thrombi with positive ApoE staining were detected in the AD-ApoE Kyoto and AD-ApoE Sendai groups. The Oil-red O-positive glomerular area tended to be higher in the AD-ApoE Kyoto group (9.2%) than in the AD-ApoE Sendai (3.9%), AD-ApoE3 (4.8%), AD-eGFP (2.9%), and ApoE (−/−) (3.6%) groups. The atherosclerotic plaque area in the aorta was lower in the group injected with various ApoE mutations than in the group without injection of ApoE mutation.ConclusionsIn this animal study, we first established an ApoE Kyoto mutation murine model and confirmed its pathogenic role in LPG. Our results suggested that LPG may be more severe with the ApoE Kyoto than with the ApoE Sendai.

Cognitive decline in amyotrophic lateral sclerosis: Neuropathological substrate and genetic determinants.

Cognitive impairment and behavioral changes in amyotrophic lateral sclerosis (ALS) are now recognized as part of the disease. Whether it is solely related to the extent of TDP‐43 pathology is currently unclear. We aim to evaluate the influence of age, genetics, neuropathological features, and concomitant pathologies on cognitive impairment in ALS patients. We analyzed a postmortem series of 104 ALS patients and retrospectively reviewed clinical and neuropathological data. We assessed the burden and extent of concomitant pathologies, the role of APOE ε4 and mutations, and correlated these findings with cognitive status. We performed a logistic regression model to identify which pathologies are related to cognitive impairment. Cognitive decline was recorded in 38.5% of the subjects. Neuropathological features of frontotemporal lobar degeneration (FTLD) were found in 32.7%, explaining most, but not all, cases with cognitive impairment. Extent of TDP‐43 pathology and the presence of hippocampal sclerosis were associated with cognitive impairment. Mutation carriers presented a higher burden of TDP‐43 pathology and FTLD more frequently than sporadic cases. Most cases (89.4%) presented some degree of concomitant pathologies. The presence of concomitant pathologies was associated with older age at death. FTLD, but also Alzheimer’s disease, were the predominant underlying pathologies explaining the cognitive impairment in ALS patients. In sum, FTLD explained the presence of cognitive decline in most but not all ALS cases, while other non‐FTLD related findings can influence the cognitive status, particularly in older age groups.

Hereditary Apolipoprotein A-1 Amyloidosis With Glu34Lys Mutation Treated by Liver Transplantation: A Case Report

Hereditary apolipoprotein A-1 (ApoA-1) amyloidosis is a rare disease characterized by progressive deposition of amyloid fibrils in the kidney, heart, and liver. We observed a 45-year-old male patient with liver failure. Liver dysfunction was detected at 30 years of age during an annual health check-up. At 35 years of age, renal dysfunction was also found. At 40 years of age, the pathologic findings of the liver revealed amyloid deposition. A testis biopsy specimen taken at 42 years of age to identify the cause of male infertility showed amyloid accumulation. At 43 years of age, the amyloid results and genetic profile led to a definitive diagnosis of hereditary ApoA-1 amyloidosis caused by Glu34Lys mutation. A family history was absent. Liver failure showed Budd-Chiari–like formation, including enlargement of the caudate lobe and liver congestion. Although the patient showed end-stage liver cirrhosis and renal failure, only liver transplant was performed considering the burden for a living donor. The enlarged liver (4.9 kg) showed amyloid deposition in parenchyma and the space of Disse. Amyloid also accumulated in the giant spleen. The APOA1 mutation Glu34Lys is extremely rare, and in this case hepatic failure was successfully treated by liver transplant to both replace organ function and reduce production of the amyloidogenic ApoA-1–variant protein. Careful observation for reaccumulation of amyloidosis in the organ is required.

Apolipoprotein genetic variants and hereditary amyloidosis.

Amyloidosis is caused by the deposition of misfolded aggregated proteins called amyloid fibrils that in turn cause organ damage and dysfunction. In this review, we aim to summarize the genetic, clinical, and histological findings in apolipoprotein-associated hereditary amyloidosis and the growing list of mutations and apolipoproteins associated with this disorder. We also endeavor to summarize the features of apolipoproteins that have led them to be overrepresented among amyloidogenic proteins. Additionally, we aim to distinguish mutations leading to amyloidosis from those that lead to inherited dyslipidemias. Apolipoproteins are becoming increasingly recognized in hereditary forms of amyloidosis. Although mutations in APOA1 and APOA2 have been well established in hereditary amyloidosis, new mutations are still being detected, providing further insight into the pathogenesis of apolipoprotein-related amyloidosis. Furthermore, amyloidogenic mutations in APOC2 and APOC3 have more recently been described. Although no hereditary mutations in APOE or APOA4 have been described to date, both protein products are amyloidogenic and frequently found within amyloid deposits. Understanding the underlying apolipoprotein mutations that contribute to hereditary amyloidosis may help improve understanding of this rare but serious disorder and could open the door for targeted therapies and the potential development of new treatment options.

The ANeED study: Ambroxol in new and early dementia with Lewy bodies

AbstractBackgroundThe mechanisms by which GBA and APOE mutations result in PD or DLB are not fully understood, however there is evidence that it may be connected to reduced levels of GCase enzyme activity. CNS penetration has been confirmed for Ambroxol, and has been shown to increase glucocerebrosidase activity and protein levels in animal and human studies. One small open study with Ambroxol 420mg TID in PD for 186 days found excellent target engagement and improved motor symptoms, and a RCT with 50 PDD patients is ongoing in London, Canada.MethodWe will execute a national multicenter phase III RCT clinical intervention study with Ambroxol in prodromal and mild DLB in Memory Clinics in Norway. We will include persons living with prodromal (DLB‐MCI) or mild DLB with MMSE >=15 to Ambroxol or placebo. We will stratify participants based on genotypes for APOE and GBA and the CSF biomarkers A‐beta, total and phosphorylated tau protein. We will build a national trial platform for drug trials in neurodegenerative disorders in Norway and aim to include more centers in Europe for next phase studies via the European DLB Consortium (E‐DLB). We will execute a PPI program to raise awareness and reduce stigma for people living with DLB and their families.ResultThe ANeED‐study has received funding from the national Norwegian health authorities. Formal approvals for ethics, data protection and Medicine Agency are ongoing. We are planning a national start‐up meeting in Norway in September 2020, and we are currently building a national platform in Norway to be able to run clinical intervention studies in neurodegenerative disorders. We are building a PPI program to recruit patients and caregivers to clinical studies.ConclusionPhase III studies with Ambroxol in PD, PDD and DLB are currently being planned. APOE, GBA and GCase are central to the disease process in both PD, PDD and in DLB. Patients, carers and health providers now need to be offered participation in clinical studies also when diagnosed with one of the α‐synucleinopathies. Preliminary data find Ambroxol to be potentially disease modifying in these disorders.

Targeted Genetic Analysis in a Chinese Cohort of 208 Patients Related to Familial Hypercholesterolemia.

Aim: Familial hypercholesterolemia (FH) is the most commonly encountered genetic condition that predisposes individuals to severe autosomal dominant lipid metabolism dysfunction. Although more than 75% of the European population has been scrutinized for FH-causing mutations, the genetic diagnosis proportion among Chinese people remains very low (less than 0.5%). The aim of this study was to identify genetic mutations and help make a precise diagnosis in Chinese FH patients.Methods: We designed a gene panel containing 20 genes responsible for FH and tested 208 unrelated Chinese possible/probable or definite FH probands. In addition, we called LDLR copy number variation (CNVs) with the panel data by panelcn.MOPS, and multiple ligation-dependent probe amplification (MLPA) was used to search for CNVs in LDLR, APOB, and PCSK9.Results: A total of 79 probands (38.0%) tested positive for a (likely) pathogenic mutation, most of which were LDLR mutations, and three LDLR CNVs called from the panel data were all successfully confirmed by MLPA analysis. In total, 48 different mutations were identified, including 45 LDLR mutations, 1 APOB mutation, 1 ABCG5 mutation, and 1 APOE mutation. Among them, the five most frequent mutations (LDLR c.1879G>A, c.1747C>T, c.313+1G>A, c.400T>C, and APOB c.10579C>T) were detected. Moreover, we also found that patients with LDLR variants of CNVs and splicing and nonsense had increased low-density lipoprotein cholesterol levels when compared with those who carried missense variants.Conclusions: The spectrum of FH-causing mutations in the Chinese population is refined and expanded. Analyses of FH causal genes have been a great help in clinical diagnosis and have deep implications in disease treatment. These data can serve as a considerable dataset for next-generation sequencing analysis of the Chinese population with FH and contribute to the genetic diagnosis and counseling of FH patients.

Clinical and genetic analysis of lipoprotein glomerulopathy patients caused by APOE mutations.

BackgroundLipoprotein glomerulopathy (LPG) is a rare kidney disease caused by APOE mutations. The aim of this study was to correlate the genetic and clinical features of LPG.MethodsTotally eight LPG patients were recruited in this study and Sanger sequencing of APOE was performed for all available family members. Clinical and histological features were analyzed. A literature review of LPG was also conducted.ResultsGenetic analysis revealed five patients with APOE‐Kyoto, two with APOE‐Osaka/Kurashiki, and one with APOE‐Chicago mutations. LPG patients with urine protein reduced more than 50% had a slower decrease in renal function than those with less urine protein reduction (estimated glomerular filtration rate reduction rate −5.0 ± 0.8 vs. 1.5 ± 0.7 ml/min per 1.73 m2⋅month−1, p = .03). We then enrolled 95 LPG patients from previous studies and this study. LPG patients had higher blood pressure (mean arterial pressure: 109.4 ± 19.4 vs. 94.4 ± 11.1 mmHg, p < .001) than the control group. Interestingly, patients with APOE mutations in the LDL receptor binding region had higher serum apolipoprotein E (apoE) levels [ln(apoE): 2.7 ± 0.4 vs. 2.0 ± 0.5 mg/dl, p < .001] in comparison to other domains.ConclusionHere, we report for the first time APOE‐Osaka/Kurashiki and APOE‐Chicago mutations in the Chinese population. LPG was associated with higher blood pressure and serum apoE levels were higher in patients with mutations in LDL receptor binding region. In addition, the findings further indicated that treatment of proteinuria might slow down renal function progression in these patients.

Low cholesterol syndrome and drug development.

Low cholesterol syndromes were considered curiosities. The present article reviews some hypolipidaemic disorders and the drugs developed from the insights they provided. Abetalipopoproteinaemia and hypobetalipoproteinaemia are associated with low cholesterol concentrations and caused by mutations in apolipoprotein (apo) B or microsomal transfer protein. This led to the development of mipomersen and lomitapide which are used to treat homozygous familial hypercholesterolaemia. Mutations in proprotein convertase subtilisin kexin-9 (PCSK9) can cause either high or low cholesterol. Loss of function PCSK9 mutations prompted the development of antibody therapies to PCSK9 which are now widely used to treat hypercholesterolaemia. Mutations in apolipoprotein C-3 and angiopoietin-like protein 3 (ANGPTL3) cause hypolipoproteinaemia and reduced triglycerides. Antisense therapies to apolipoprotein C-3 and antibodies to ANGPTL3 are in development to treat familial chylomicronaemia syndrome. Activating mutations in apoA-1 result in hyper-functioning high-density lipoprotein (HDL) and suggest that modifying HDL turnover may reduce cardiovascular disease (CVD) risk. Orphan lipid disorders have provided insights into mechanisms involved in lowering cholesterol levels and the potential safety and efficacy of interventional processes. They have been not only enabled development of drugs to treat rare lipid disorders but also those finding wider use in general lowering of CVD risk.

Clinicopathologic and genetic features of multiple system atrophy with Lewy body disease.

Background: Abnormal aggregates of α‐synuclein are pathologic hallmarks of multiple system atrophy (MSA) and Lewy body disease (LBD). LBD sometimes coexists with MSA, but the impact of co‐pathology, particularly diffuse LBD, on presentation of MSA has not been studied. We aimed to determine the frequency and clinicopathologic features of MSA with LBD (MSA+LBD). Methods: Using hematoxylin & eosin and α‐synuclein‐immunostained slides, we assessed the distribution and severity of LBD in 230 autopsy‐confirmed MSA patients collected from 1998 to 2018. Alzheimer‐type pathology was assessed to assign the likelihood of clinical presentations of dementia with Lewy body (DLB) using the consensus criteria for DLB. We reviewed medical records to characterize clinicopathologic features of MSA+LBD. Genetic risk factors for LBD, including APOE ε4 allele and mutations in GBA, SNCA, LRRK2, and VPS35, were analyzed. Results: LBD was observed in 11 MSA patients (5%); seven were brainstem type, three were transitional type, and one was diffuse type. The latter four had an intermediate or high likelihood of DLB. Three of the four had an antemortem diagnosis of Parkinson’s disease with dementia (PDD) or clinically probable DLB. Two patients had neuronal loss in the substantia nigra, but not in striatal or olivocerebellar systems with widespread glial cytoplasmic inclusions, consistent with minimal change MSA. In these cases, LBD was considered the primary pathology, and MSA was considered coincidental. APOE ε4 allele frequency was not different between MSA+LBD and MSA without LBD. Two of nine MSA+LBD patients had a risk variant of GBA (p.T408M and p.E365K). Conclusions: Although rare, MSA with transitional or diffuse LBD can develop clinical features of PDD or DLB. Minimal change MSA can be interpreted as a coincidental, but distinct, α‐synucleinopathy in a subset of patients with diffuse LBD.

Inborn errors of apolipoprotein A-I metabolism: implications for disease, research and development.

We review current knowledge regarding naturally occurring mutations in the human apolipoprotein A-I (APOA1) gene with a focus on their clinical complications as well as their exploitation for the elucidation of structure-function-(disease) relationships and therapy. Bi-allelic loss-of-function mutations in APOA1 cause HDL deficiency and, in the majority of patients, premature atherosclerotic cardiovascular disease (ASCVD) and corneal opacities. Heterozygous HDL-cholesterol decreasing mutations in APOA1 were associated with increased risk of ASCVD in several but not all studies. Some missense mutations in APOA1 cause familial amyloidosis. Structure-function-reationships underlying the formation of amyloid as well as the manifestion of amyloidosis in specific tissues are better understood. Lessons may also be learnt from the progress in the treatment of amyloidoses induced by transthyretin variants. Infusion of reconstituted HDL (rHDL) containing apoA-I (Milano) did not cause regression of atherosclerosis in coronary arteries of patients with acute coronary syndrome. However, animal experiments indicate that rHDL with apoA-I (Milano) or apoA-I mimetic peptides may be useful for the treatment of heart failure of inflammatory bowel disease. Specific mutations in APOA1 are the cause of premature ASCVD or familial amyloidosis. Synthetic mimetics of apoA-I (mutants) may be useful for the treatment of several diseases beyond ASCVD.

MiR-532-3p-CSF2RA Axis as a Key Regulator of Vulnerable Atherosclerotic Plaque Formation

BackgroundThe most dangerous atherosclerotic plaques, referred to as “vulnerable,” are most likely to trigger acute atherothrombotic events such as myocardial infarction (heart attack) and stroke. Our goal was to uncover the molecular drivers of vulnerable plaque formation. MethodsTo elucidate the functional gene modules that drive vulnerable plaque formation, we performed a weighted gene coexpression network analysis integrated with a protein-protein interaction network analysis in human atherosclerotic carotid samples, which identified the candidate gene granulocyte-macrophage colony-stimulating factor 2 (GM-CSF) receptor alpha subunit (CSF2RA). Follow-up in vitro experiments were performed to elucidate the regulatory relationship between CSF2RA and the microRNA miR-532-3p as well as modifiers of macrophagic miR-532-3p-CSF2RA axis expression. Microarray and quantitative reverse transcription polymerase chain reaction (qRT-PCR) studies elucidated the effect of statins on carotid miR-532-3p-CSF2RA axis expression in patients with carotid atherosclerotic disease. Apoe−/−, Ldlr−/−, and Csf2ra mutant Apoe−/− mouse models of atherosclerosis were employed to assess the effects of agomiR-532-3p therapy in vivo. ResultsThe integrated weighted gene coexpression network analysis/protein-protein interaction network analysis revealed that the macrophagic GM-CSF receptor CSF2RA is significantly upregulated in macrophage-rich vulnerable plaques. Follow-up analysis identified the miR-532-3p-CSF2RA axis, as miR-532-3p downregulates CSF2RA via binding to CSF2RA’s 3′UTR. Macrophagic miR-532-3p-CSF2RA dysregulation was enhanced via modified low-density lipoprotein or tumor necrosis factor α exposure in vitro. Moreover, this miR-532-3p-CSF2RA dysregulation was observed in human vulnerable plaques and Apoe−/− mouse plaques, effects rescued by statin therapy. In vivo, agomiR-532-3p therapy suppressed murine plaque formation and promoted plaque stabilization in a Csf2ra-dependent manner. ConclusionMacrophagic miR-532-3p-CSF2RA axis dysregulation is a key driver in vulnerable plaque formation.

Predicted pathogenic mutations in STAP1 are not associated with clinically defined familial hypercholesterolemia

Background and aimsAutosomal dominant familial hypercholesterolemia (FH) is caused by mutations in LDLR,APOB and PCSK9. Two new putative loci causing FH have been identified recently, the p.(Leu167del) mutation in APOE and new mutations in the signal transducing adaptor family member STAP1. We aimed at investigating the role of STAP1 mutations in the etiology of FH. MethodsWe sequenced LDLR, APOB, PCSK9, LDLRAP1, APOE, LIPA and STAP1 with the LipidInCode platform in 400 unrelated subjects from Spain with a clinical diagnosis of FH. All subjects carrying rare predicted pathogenic variants in STAP1 gene, described as pathogenic by at least three bioinformatic analysis and having an allelic frequency lower than 1% in general population, were selected for family study. Available relatives were recruited, including both hypercholesterolemic and non-hypercholesterolemic family members. ResultsSequencing analysis of STAP1 gene revealed seventeen rare variants, four of them being described as pathogenic by bioinformatic analysis. We studied the cosegregation with hypercholesterolemia of four rare predicted pathogenic variants, c.-60A > G, p.(Arg12His), p.(Glu97Asp), p.(Pro176Ser) in seven families. We did not observe any cosegregation between genotype and phenotype, even carriers of rare variants in STAP1 had lower LDL cholesterol levels than non-carriers. ConclusionsThis study analyzes the family cosegregation of four rare predicted pathogenic variants of STAP1, p.(Arg12His), p.(Glu97Asp), p.(Pro176Ser) and c.-60A > G, in seven families, showing absence of cosegregation in all of them. These results would suggest that STAP1 gene is not involved in hypercholesterolemia of these families.

Sensitivity Of The Clinical Criteria For Suspected Familial Hypercholesterolemia In The Detection Of Diagnostic Mutations Of The Disease

Background and Aims: Familial Hypercholesterolemia (FH) is characterized by high LDL-cholesterol levels and high cardiovascular risk, being caused by mutations in LDLR, APOB, PCSK9, APOE, STAP1 or LDLRAP1 genes. The European Atherosclerosis Society (EAS) has recommended some criteria of clinical suspicion, but their sensitivity and efficiency have not been studied.

A novel apolipoprotein E mutation caused by a five amino acid deletion in a Chinese family with lipoprotein glomerulopathy: a case report

BackgroundLipoprotein glomerulopathy (LPG) is a rare kidney disease with a poor prognosis that is related to mutation of the apoE gene. More than 10 variants of apoE associated with LPG have currently been identified.Case presentationA male and his mother presented with proteinuria during a health examination. They went to hospital for further examination. Renal biopsy was performed, and the diagnosis was lipoprotein glomerulopathy (LPG), which is a rare, inherited renal disease. Medical histories were collected from the 2 LPG patients and their family members. The patients and family members underwent a routine urine test, and their renal function, blood lipids, and lipoprotein levels were examined. Genomic DNA was extracted from the peripheral blood of 7 family members, and exon 2, exon 3 and exon 4 of apoE were amplified by polymerase chain reaction (PCR). The purified PCR products were sequenced. Sequence analysis identified a 15 bp deletion (GCGCAAGCTGCGTAA) in exon 4 of the apoE gene that results in a novel 5 amino acid deletion in apoE (143 K-147R → 0). No mutations were found in exon 2 and exon 3 of the apoE gene.ConclusionsThis family study suggests that a novel ApoE mutation (143 K-147R → 0) may be etiologically related to LPG, and other genetic or environmental factors may be associated with the occurrence of LPG.