Integrated analysis of microRNA and mRNA expression profiles in homozygous familial hypercholesterolemia patients and validation of atherosclerosis associated critical regulatory network.

Homozygous familial hypercholesterolemia (HoFH) is a rare, life-threatening genetic disorder characterized by an extremely elevated serum level of low-density lipoprotein cholesterol (LDL-C) and accelerated premature atherosclerotic cardiovascular diseases (ASCVD). However, the detailed mechanism of how the pathogenic mutations of HoFH trigger the acceleration of ASCVD is not well understood. Therefore, we performed high-throughput RNA and small RNA sequencing on the peripheral blood RNA samples of six HoFH patients and three healthy controls. The gene and miRNA expression differences were analyzed, and seven miRNAs and six corresponding genes were screened out through regulatory network analysis. Validation through quantitative PCR of genes and miRNAs from 52 HoFH patients and 20 healthy controls revealed that the expression levels of hsa-miR-486-3p, hsa-miR-941, and BIRC5 were significantly upregulated in HoFH, while ID1, PLA2G4C, and CACNA2D2 were downregulated. Spearman correlation analysis found that the levels of ID1, hsa-miR-941, and hsa-miR-486-3p were significantly correlated with additional ASCVD risk factors in HoFH patients. This study represents the first integrated analysis of transcriptome and miRNA expression profiles in patients with HoFH, a rare disease, and as a result, six differentially expressed miRNAs/genes that may be related to atherosclerosis in HoFH are reported. The miRNA-mRNA regulatory network may be the critical regulation mechanism by which ASCVD is accelerated in HoFH.

Prognostic value of coronary flow velocity reserve in patients with homozygous familial hypercholesterolemia.

BACKGROUND: Coronary flow velocity reserve (CFVR) can provide useful quantitative information on the functional status of coronary artery circulation, and an impaired CFVR (< 2.0) was associated with a significant increase in the occurrence of cardiac events. Coronary artery disease (CAD) is the leading cause of death in homozygous familial hypercholesterolemia (HoFH), but the relationship between impaired CFVR and outcome in HoFH has never been discussed before METHODS: To explore the long-term prognostic value of CFVR in patients with HoFH, 39 HoFH patients with CFVR data (mean age with 16.7 years) were enrolled from the Genetic and Imaging of Familial Hypercholesterolemia in Han Nationality Study. All patients were divided into impaired CFVR (CFVR < 2.0, n = 17) and preserved CFVR (CFVR≥2.0, n = 22) group. Follow-up was performed until a major adverse cardiac event (MACE) occurred or up to June 30, 2020 RESULTS: During a median follow-up of 89 months, 16 events were registered, 12 of which were occurred in the impaired CFVR group and four occurred in the preserved CFVR group. The event-free survival rate of impaired CFVR group was significantly lower than that in the preserved CFVR group (29.4% vs 81.8%, P < .001), and CFVR < 2.0 was independently associated with prognosis before and after adjustment for related risk factors (HR 5.197, 95% CI 1.669 to 16.178, P = .004 and HR 5.488, 95% CI 1.470 to 20.496, P = .011, respectively) CONCLUSIONS: an impaired CFVR predicts a worse outcome in HoFH. CFVR shows an independent value in the prediction of long-term outcome in HoFH.

Comparison of long-term outcomes of young patients after a coronary event associated with familial hypercholesterolemia.

OBJECTIVE: Familial hypercholesterolemia (FH) is an important cause of premature coronary artery disease (CAD). Prognosis data are lacking in patients with FH and coronary artery disease particularly in the era of widespread statin use. We compared long-term prognosis between patients with and without FH after a coronary event. METHODS: In this retrospective study, 865 patients younger than 40 years of age with CAD were enrolled. FH was diagnosed based on the Dutch Lipid Clinic Network algorithm. Baseline characteristics, coronary angiographic findings and prognosis during median follow-up of 5 (3-8) years were compared between patients with or without FH. RESULTS: Definite or probable FH was detected in 37 patients (4.3%) and possible FH in 259 patients (29.9%). FH was associated with significantly higher prevalence of multi-vessel lesions (p < 0.001) and higher Gensini score (p = 0.008). In the subset of 706 patients for whom follow-up data were available, 127 (18.0%) suffered major adverse cardiovascular and cerebrovascular events (MACCE). FH was associated with increased risk of MACCE, independently of age, sex, smoking, body mass index, hypertension or diabetes mellitus (HR = 2.30, 95%CI = 1.09 to 4.84, p = 0.028). CONCLUSIONS: FH is an independent risk factor for MACCE in young patients after a coronary event during long-term follow-up. It is necessary to optimize lipid treatment of patients with FH after a coronary event.

Order-of-magnitude multiphoton signal enhancement based on characterization of absorption spectra of immersion oils at the 1700-nm window.

To enhance signal levels in multiphoton microscopy (MPM) at the deep-tissue excitation window (1600-1820 nm) with oil immersion, we demonstrate: First, the absorption spectra of several commonly immersion oils are characterized, which were unknown before. Second, new material with lower absorption based on mixing is proposed. Third, optimal selection of excitation wavelength within this window is proposed based on absorption spectra characterization. Second and third harmonic generation imaging of mouse tissue corroborate our selection: 1600-nm excitation leads to notable orders-of-magnitude increase in MPM signal, compared with 1700-nm excitation, enabling 200-µm imaging depth of mouse skin while 1700-nm excitation could resolve virtually no structure.

Supravalvular Aortic Stenosis and the Risk of Premature Death Among Patients With Homozygous Familial Hypercholesterolemia.

Patients with homozygous familial hypercholesterolemia (HoFH) have a high risk for premature death. Supravalvular aortic stenosis (SVAS) is a common and the feature lesion of the aortic root in HoFH. The relation between SVAS and the risk of premature death in patients with HoFH has not been fully investigated. The present study analysis included 97 HoFH patients with mean age of 14.7 (years) from the Genetic and Imaging of Familial Hypercholesterolemia in Han Nationality Study. During the median (±SD) follow-up 4.0 (±4.0) years, 40 (41.2%) participants had SVAS and 17 (17.5%) participants experienced death. The proportion of premature death in the non-SVAS and SVAS group was 7.0% and 32.5%, respectively. Compared with the non-SVAS group, SVAS group cumulative survival was lower in the HoFH (log-rank test, p <0.001). This result was further confirmed in the multivariable Cox regression models. After adjusting for age, sex, low density lipoprotein cholesterol (LDL_C)-year-score, lipid-lowering drugs, cardiovascular disease, and carotid artery plaque, SVAS was an independent risk factor of premature death in HoFH on the multivariate analysis (hazard ratio 4.45; 95% confidence interval, 1.10 to 18.12; p = 0.037). In conclusion, a significantly increased risk of premature death was observed in HoFH patients with SVAS. Our study emphasized the importance of careful and aggressive management in these patients when appropriate.

Features of Sitosterolemia in Children.

Sitosterolemia is a rare lipid metabolism disease with heterogeneous manifestations. Atherosclerosis can occur in children, and therefore, early detection, diagnosis, and treatment of this disease are important. We studied 18 pediatric patients with sitosterolemia who showed a significant increase in plasma lipid levels and analyzed their clinical, biochemical, and genetic characteristics. We recorded the initial serum lipid results and clinical manifestations of the patients. Lipid and plant sterol levels were measured after homozygous or compound heterozygous mutations of ABCG5 or ABCG8 were identified by genetic testing. Plasma plant sterol levels were analyzed by gas chromatography. Fourteen cases of sitosterolemia were examined by ultrasound and echocardiography. The initial total cholesterol and low-density lipoprotein levels of the children were significantly increased, but then markedly decreased after diet control or drug treatment, and even reached normal levels. Carotid atherosclerosis and aortic valve regurgitation were present in three of 14 patients. Serum lipid levels of children with sitosterolemia and xanthomas were notably higher than those without xanthomas. There were no significant differences in clinical manifestations between patients with different genotypes. In conclusion, sitosterolemia should be considered in children with hyperlipidemia who do not present with xanthomas, especially with a significant increase in total cholesterol and low-density lipoprotein levels. There does not appear to be a correlation between clinical phenotype and genotype.

Visualizing astrocytes in the deep mouse brain in vivo.

Astrocytes play a key role in the central nervous system. However, methods of visualizing astrocytes in the deep brain in vivo have been lacking. 3-photon fluorescence imaging of astrocytes labeled by sulforhodamine 101 (SR101) is demonstrated in deep mouse brain in vivo. Excitation wavelength selection was guided by wavelength-dependent 3-photon action cross section (ησ 3 ) measurement of SR101. 3-photon fluorescence imaging of the SR101-labeled vasculature enabled an imaging depth of 1340-µm into the mouse brain. This justifies the deep imaging capability of the technique and indicates that the imaging depth is not determined by the signal-to-background ratio limit encountered in 2-photon fluorescence imaging. Visualization of astrocytes 910 µm below the surface of the mouse brain in vivo is demonstrated, 30% deeper than that using 2-photon fluorescence microscopy. Through quantitative comparison of the signal difference between the SR101-labeled blood vessels and astrocytes, the challenges of visualizing astrocytes below the white matter is further elucidated.

Refractive index and pulse broadening characterization using oil immersion and its influence on three-photon microscopy excited at the 1700-nm window.

Three-photon microscopy excited at the 1700-nm window enables deep-tissue penetration. However, the refractive indices of commonly used immersion oils, and the resultant pulse broadening are not known, preventing imaging optimization. Here, we demonstrate detailed characterization of the refractive index, pulse broadening and distortion for excitation pulses at this window for commonly used immersion oils. On the physical side, we uncover that absorption, rather than material dispersion, is the main cause of pulse broadening and distortion. On the application side, comparative three-photon imaging results indicate that 1600-nm excitation yields 5 times higher three-photon signal than 1690-nm excitation.

Visualizing the "sandwich" structure of osteocytes in their native environment deep in bone in vivo.

Osteocytes are the most abundant cells in bone and always the focus of bone research. They are embedded in the highly scattering mineralized bone matrix. Consequently, visualizing osteocytes deep in bone with subcellular resolution poses a major challenge for in vivo bone research. Here we overcome this challenge by demonstrating 3-photon imaging of osteocytes through the intact mouse skull in vivo. Through broadband transmittance characterization, we establish that the excitation at the 1700-nm window enables the highest optical transmittance through the skull. Using label-free third-harmonic generation (THG) imaging excited at this window, we visualize osteocytes through the whole 140-µm mouse skull and 155 µm into the brain in vivo. By developing selective labeling technique for the interstitial space, we visualize the "sandwich" structure of osteocytes in their native environment. Our work provides novel imaging methodology for bone research in vivo.

Independent Severe Cases of Heterozygous Familial Hypercholesterolemia Caused by the W483X and Novel W483G Mutations in the Low-Density Lipoprotein Receptor Gene That Were Clinically Diagnosed as Homozygous Cases.

Background and Aims: The genetic spectrum underlying familial hypercholesterolemia (FH) remains unclear, especially in northeastern China. The aim of this study was to delineate the FH genetic spectrum and identify specific characteristics of FH patients in this region. Materials and Methods: The family history, personal medical history, and lifestyle habits of two unrelated patients clinically diagnosed with homozygous FH were recorded. DNA samples of the patients and their relatives were subjected to a newly designed next-generation sequencing panel using an Illumina Miseq platform. Detected variants were annotated and functionally predicted with in silico algorithms, and protein structures were modeled. Results: The patients' cholesterol levels were effectively reduced to 33.8% and 17.2% of the original level under conventional ezetimibe and statin treatment. Two pathogenic mutations, W483X and the novel mutation W483G, in the low-density lipoprotein receptor (LDLR) gene were identified. Both patients were heterozygous for the respective mutations. Under a high cholesterol/carbohydrate diet, these mutations could trigger a severe FH phenotype, but both patients responded well to regular medical treatments and dietary control. The W483X mutation results in a premature stop codon, leading to incomplete protein formation. Although the W483G mutation results in translation of the complete protein with no apparent structural difference, it still led to a severe FH phenotype similar to W483X. Conclusions: Identification of the novel W483G mutation expands the genetic spectrum of FH. Both mutations cause a severe FH phenotype under certain conditions, suggesting that W483 is important for LDLR function, highlighting potential targets for genetic screening or drug development.

Comparison of higher-order multiphoton signal generation and collection at the 1700-nm window based on transmittance measurement of objective lenses.

One benefit of excitation at the 1700-nm window is the more accessible modalities of multiphoton signal generation. It is demonstrated here that the transmittance performance of the objective lens is of vital importance for efficient higher-order multiphoton signal generation and collection excited at the 1700-nm window. Two commonly used objective lenses for multiphoton microscopy (MPM) are characterized and compared, one with regular coating and the other with customized coating for high transmittance at the 1700-nm window. Our results show that, fourth harmonic generation imaging of mouse tail tendon and 5-photon fluorescence of carbon quantum dots using the regular objective lens shows an order of magnitude signal higher than those using the customized objective lens. Besides, the regular objective lens also enables a 3-photon fluorescence imaging depth of >1600 µm in mouse brain in vivo. Our results will provide guidelines for objective lens selection for MPM at the 1700-nm window.

Genetically confirmed familial hypercholesterolemia in outpatients with hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is an autosomal dominant disorder of lipoprotein metabolism which can lead to premature coronary heart disease (pCHD). There are about 3.8 million potential FH patients in China, whereas the clinical and genetic data of FH are limited. METHODS: Dutch Lipid Clinic Network (DLCN) criteria was used to diagnose FH in outpatients with hypercholesterolemia. Resequencing chip analysis combined with Sanger sequencing validation were used to identify mutations in the definite FH patients according to DLCN criteria. In silico analysis was conducted in mutations with previously unknown pathogenicity. Then, the novel mutant receptors were transfected into human embryo kidney 293 (HEK-293) cells. The binding and the internalization activities of the mutant receptors were analyzed by flow cytometry. RESULTS: The prevalence of definite FH in outpatients with hypercholesterolemia in this study is 3.2%. Using genetic testing, one homozygous FH (HoFH), one heterozygous FH (HeFH) and three compound heterozygous FH patients were confirmed. Eight mutations in low-density lipoprotein receptor (LDLR) gene were identified, in which c.357delG was a novel mutation and co-segregated with the FH phenotype. Bioinformatic analysis confirmed that c.357delG was a pathogenic mutation. Furthermore, when compared with the wild-type LDLRs by flow cytometry analysis, the binding and internalization activities of c.357delG mutant LDLRs were reduced by 35% and 49%, respectively. CONCLUSIONS: This study identified eight LDLR gene mutations in five patients with definite FH, in which c.357delG is a novel pathogenic mutation. These findings increase our understanding of the genetic spectrum of FH in China.