Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function.

Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (APOB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic depletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor-associated cholesterol deposits, and photoreceptor cell death, and loss of rod but not cone function. RPE-specific reduction in Mttp had no significant effect on plasma lipids and lipoproteins. While APOB was decreased in the RPE, most ocular retinoids remained unchanged, with the exception of the storage form of retinoid, retinyl ester. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but is not directly involved in plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.

Discordance among apoB, non-high-density lipoprotein cholesterol, and triglycerides: implications for cardiovascular prevention.

BACKGROUND AND AIMS: Despite growing evidence that apolipoprotein B (apoB) is the most accurate marker of atherosclerotic cardiovascular disease (ASCVD) risk, its adoption in clinical practice has been low. This investigation sought to determine whether low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (HDL-C), and triglycerides are sufficient for routine cardiovascular care. METHODS: A sample of 293 876 UK Biobank adults (age: 40-73 years, 42% men), free of cardiovascular disease, with a median follow-up for new-onset ASCVD of 11 years was included. Distribution of apoB at pre-specified levels of LDL-C, non-HDL-C, and triglycerides was examined graphically, and 10-year ASCVD event rates were compared for high vs. low apoB. Residuals of apoB were constructed after regressing apoB on LDL-C, non-HDL-C, and log-transformed triglycerides and used as predictors in a proportional hazards regression model for new-onset ASCVD adjusted for standard risk factors, including HDL-C. RESULTS: ApoB was highly correlated with LDL-C and non-HDL-C (Pearson's r = .96, P < .001 for both) but less so with log triglycerides (r = .42, P < .001). However, apoB ranges necessary to capture 95% of all observations at pre-specified levels of LDL-C, non-HDL-C, or triglycerides were wide, spanning 85.8-108.8 md/dL when LDL-C 130 mg/dL, 88.3-112.4 mg/dL when non-HDL-C 160 mg/dL, and 67.8-147.4 md/dL when triglycerides 115 mg/dL. At these levels (±10 mg/dL), 10-year ASCVD rates for apoB above mean + 1 SD vs. below mean - 1 SD were 7.3 vs. 4.0 for LDL-C, 6.4 vs. 4.6 for non-HDL-C, and 7.0 vs. 4.6 for triglycerides (all P < .001). With 19 982 new-onset ASCVD events on follow-up, in the adjusted model, residual apoB remained statistically significant after accounting for LDL-C and HDL-C (hazard ratio 1.06, 95% confidence interval 1.0-1.07), after accounting for non-HDL-C and HDL-C (hazard ratio 1.04, 95% confidence interval 1.03-1.06), and after accounting for triglycerides and HDL-C (hazard ratio 1.13, 95% confidence interval 1.12-1.15). None of the residuals of LDL-C, non-HDL-C, or of log triglycerides remained significant when apoB was included in the model. CONCLUSIONS: High variability of apoB at individual levels of LDL-C, non-HDL-C, and triglycerides coupled with meaningful differences in 10-year ASCVD rates and significant residual information contained in apoB for prediction of new-onset ASCVD events demonstrate that LDL-C, non-HDL-C, and triglycerides are not adequate proxies for apoB in clinical care.

Bacterial lipopolysaccharide forms aggregates with apolipoproteins in male and female rat brains after ethanol binges.

Alcohol binge drinking allows the translocation of bacterial lipopolysaccharide (LPS) from the gut to the blood, which activates the peripheral immune system with consequences in neuroinflammation. A possible access/direct signaling of LPS to/in the brain has not yet been described under alcohol abuse conditions. Apolipoproteins are compounds altered by alcohol with high affinity to LPS which may be involved in its transport to the brain or in its elimination. Here, we explored the expression of small components of LPS, in its free form or bound to apolipoproteins, in the brain of female and male rats exposed to alcohol binges. Animals received ethanol oral gavages (3 g/kg every 8 h) for 4 days. LPS or its components (Lipid A and core), LPS-binding protein, corticosterone, lipoproteins (HDL, LDL), apolipoproteins (ApoAI, ApoB, and ApoE), and their receptors were measured in plasma and/or in nonperfused prefrontal cortex (PFC) and cerebellum. Brain LipidA-apolipoprotein aggregates were determined by Western blotting and confirmed by co-immunoprecipitation. In animals exposed to alcohol binges: 1) plasma LPS-binding protein was elevated in both sexes; 2) females showed elevations in plasma ApoAI and corticosterone levels; 3) Lipid A formed aggregates with ApoAI in the female PFC and with ApoB in males, the latter showing Toll-like receptor 4 upregulation in PFC but not females. These results suggest that small bacterial components are present within the brain, forming aggregates with different apolipoproteins, depending on the sex, after alcohol binge intoxications. Results may have implications for the crosstalk between alcohol, LPS, and neuroinflammation.

Haplotype analysis and linkage disequilibrium of ApoB gene polymorphisms and its relationship with hyperlipidemia in patients with acne vulgaris.

BACKGROUND: Acne vulgaris (AV) is a chronic, multifactorial inflammatory disease of the pilosebaceous unit brought on by hormonal imbalance, excessive sebum production, follicular hyperkeratinization, inflammation and Cutibacterium acne. Acne patients are characterized by alteration of the lipid profile. Apolipoprotein B gene (ApoB) plays an essential role in lipoprotein biosynthesis and multiple single-nucleotide polymorphisms (SNPs) in ApoB are associated with dyslipidemia. AIM: The aim of this study was to estimate the alteration of lipid profiles in AV, determine the genetic association with lipid profile alteration by studying the ApoB gene polymorphisms, and to identify the exact haplotypes associated with acne and lipid profile alteration. SUBJECTS AND METHODS: In a case-control study consisting of 63 non-obese acne patients and 43 healthy controls, all participants underwent biochemical, anthropological assessments, and genetic analysis for ApoB polymorphisms. RESULT: Our results indicate that serum ApoB and the lipid profile were higher in acne patients compared with healthy subject. The most common haplotypes in acne patients were rs562338 A/rs17240441 I/c.12669 A/rs1042034 G, whereas the most common haplotypes in healthy subjects were rs562338 G/rs17240441 D/c.12669 A/rs1042034 G. Patients with mild acne had higher serum ApoB levels p = 0.005. Also, the low-density lipoprotein cholesterol (LDL-C) level was higher in mild acne compared with other acne groups, with a highly significant variation of p ≤ 0.001. CONCLUSION: We found a significant variation between the acne group and healthy controls in serum ApoB, triglycerides, total cholesterol and LDL-C. The most common haplotypes in acne patients are rs562338 A/, rs17240441 I/, c.12669 A/ and rs1042034 G, and there is a linkage disequilibrium between the four selected SNPs.

Revisiting an old relationship: the causal associations of the ApoB/ApoA1 ratio with cardiometabolic diseases and relative risk factors-a mendelian randomization analysis.

BACKGROUND: It has been confirmed that the ApoB/ApoA1 ratio is closely associated with the incidence of cardiometabolic diseases (CMD). However, due to uncontrolled confounding factors in observational studies, the causal relationship of this association remains unclear. METHODS: In this study, we extracted the ApoB/ApoA1 ratio and data on CMD and its associated risk factors from the largest European Genome-Wide Association Study. The purpose was to conduct Mendelian Randomization (MR) analysis. The causal relationship between the ApoB/ApoA1 ratio and CMD was evaluated using both univariable and multivariable MR analyses. Furthermore, bidirectional MR analysis was performed to estimate the causal relationship between the ApoB/ApoA1 ratio and risk factors for CMD. The final verification confirmed whether the ApoB/ApoA1 ratio exhibits a mediating effect in CMD and related risk factors. RESULTS: In terms of CMD, a noteworthy correlation was observed between the increase in the ApoB/ApoA1 ratio and various CMD, including ischemic heart disease, major adverse cardiovascular events, aortic aneurysm, cerebral ischemic disease and so on (all PFDR<0.05). Meanwhile, the ApoB/ApoA1 ratio was significantly associated with CMD risk factors, such as hemoglobin A1c, fasting insulin levels, waist-to-hip ratio, sedentary behavior, and various others, demonstrating a notable causal relationship (all PFDR<0.05). Additionally, the ApoB/ApoA1 ratio played a mediating role in CMD and relative risk factors. CONCLUSIONS: This MR study provides evidence supporting the significant causal relationship between the ApoB/ApoA1 ratio and CMD and its risk factors. Moreover, it demonstrates the mediating effect of the ApoB/ApoA1 ratio in CMD and its risk factors. These findings suggest that the ApoB/ApoA1 ratio may serve as a potential indicator for identifying the risk of developing CMD in participants.

Association between Apo B, LDL-R and PCSK9 gene polymorphisms with coronary artery diseases in Egyptians.

BACKGROUND: Many studies have focused on the significance of lipid regulatory genes in the pathophysiology of Coronary artery disease (CAD). ApoB XbaI (rs693) and EcoRI (rs1042031) single nucleoid polymorphisms (SNPs) were investigated to detect whether they are risk factors for CAD. Till now, this association remains uncertain. SMARCA4 (rs1122608) SNP has directly related to dyslipidemia. Loss of function mutations (LOF) in PCSK9 result in a reduction in LDL cholesterol and are associated with protection from the development of CAD. METHODS: This study was conducted on 54 CAD patients who were admitted at Internal Medicine Specialized Hospital (Cardiology Department) and 47 healthy controls. Peripheral blood samples were taken from both groups. DNA was extracted from EDTA-blood samples, then PCR- RFLP for ApoB XbaI (rs693) and EcoRI (rs1042031), SMARCA4 (rs1122608) and PCSK9 (rs505151) SNPs was done. RESULTS: No statistically significant difference was found between patients and controls as regard EcoRI SNP. XbaI (rs693) X + X + genotype was significantly higher in control group (P = 0.0355). SMARCA4 (TT, GT + TT) genotypes, and T allele (P < 0.001); PCSK9 AG genotype and G allele (P = 0.027 and 0.032 respectively) were more frequent in CAD patients than controls. CONCLUSION: SMARCA4 (rs1122608) and PCSK9 (rs505151) SNPs are significantly accompanying with the risk of CAD development in the Egyptian population. X + X + genotype appeared to have a protective effect against CAD. However, no observed association between EcoRI (rs1042031) and the risk of CAD development was found.

Serum apolipoproteins (apoA-1, apoB, and apoB/apoA-1 ratio) for early identification of dyslipidemia in children with CKD.

BACKGROUND: Dyslipidemia in children with chronic kidney disease (CKD) is identified based on lipid profile parameters; however, changes in lipoprotein quality precede quantitative changes. METHODS: A cross-sectional study was done from January to October 2021; overweight, obese children, known cases of diabetes mellitus, hypothyroidism or on steroid therapy, or lipid lowering drugs were excluded. Clinical details were elicited and examinations done. Besides hemogram, kidney function tests, liver function tests, total cholesterol, low density lipoproteins (LDL), triglycerides, high density lipoproteins (HDL), and apolipoproteins A-1 and B were estimated to identify dyslipidemia. Relevant tests of significance were applied, and ROC curves were drawn for apoA-1, apoB, and apoB/apoA-1 ratios. RESULTS: A total of 76 (61 M:15 F) children with median (IQR) age 7 (3.25-11) years were enrolled; cause of CKD was CAKUT in 82.3% patients. Dyslipidemia (alteration of 1 or more lipid parameters) was seen in 78.9% with a prevalence of 71.7% in early and 95.7% in later stages of CKD (P = 0.02); most had elevated serum triglyceride levels. The median (IQR) values of apoB, apoA-1, and apoB/apoA-1 ratio were 78 (58-110) mg/dl, 80 (63-96.75) mg/dl, and 0.88 (0.68-1.41), respectively; apoB, apoA-1, and apoB/apoA-1 ratio had a sensitivity of 26.67%, 86.67%, and 70%, respectively, and specificity of 87.5%, 62.5%, and 62.5%, respectively, for diagnosis of dyslipidemia. The ROC for apoB, apoA-1, and apoB/apoA-1 ratio showed AUC of 0.66, 0.68, and 0.74 (P = 0.4, 0.02, < 0.01), respectively. CONCLUSIONS: The prevalence (78.9%) of dyslipidemia was high in patients with CKD especially in those with later stages. The ratio of apoB/apoA-1 was altered early and appears to be promising for early detection.

Increased Apolipoprotein B/Apolipoprotein A-I Ratio Is Associated With Decline in Lung Function in Healthy Individuals: The Kangbuk Samsung Health Study.

BACKGROUND: Lung dysfunction and high apolipoprotein B/apolipoprotein A-I (apoB/apoA-I) ratio are both recognized risk factors for cardiovascular disease. However, few studies have examined the association between the apoB/ApoA-I ratio and lung function. Therefore, we investigated whether this ratio is associated with decreased lung function in a large healthy cohort. METHODS: We performed a cohort study on 68,418 healthy Koreans (34,797 males, mean age: 38.1 years) who underwent a health examination in 2019. ApoB/apoA-I ratio was categorized into quartiles. Spirometric values at the fifth percentile in our population were considered the lower limit of normal (LLN), which was used to define lung function impairment. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs), using the lowest quartile as the reference, were estimated to determine lung function impairment. RESULTS: Mean apoB/apoA-I ratio was 0.67 ± 0.21. Subjects with the highest quartile of this ratio had the lowest predicted forced expiratory volume in one second (FEV1%) and forced vital capacity (FVC%) after controlling for covariates (P < 0.001). However, FEV1/FVC ratio was not significantly different among the four quartiles (P = 0.059). Compared with the lowest quartile (Q1, reference), the aORs (95% CI) for FEV1% < LLN across increasing quartiles (from Q2 to Q4) were 1.216 (1.094-1.351), 1.293 (1.156-1.448), and 1.481 (1.311-1.672) (P for trend < 0.001), respectively. Similarly, the aORs for FVC% < LLN compared with the reference were 1.212 (1.090-1.348), 1.283 (1.147-1.436), and 1.502 (1.331-1.695) with increasing quartiles (P for trend < 0.001). However, the aORs for FEV1/FVC < LLN were not significantly different among groups (P for trend = 0.273). CONCLUSION: High apoB/apoA-I ratio was associated with decreased lung function. However, longitudinal follow-up studies are required to validate our findings.

Early-onset Parkinson's disease with mutations in both the PRKN gene and the APOB gene: A case report. / PRKNåŸºå› åˆå¹¶APOBåŸºå› çªå˜çš„æ—©å‘åž‹å¸•é‡‘æ£®ç— 1例.

The incidence rate of Parkinson's disease ranks the second among degenerative diseases of the nervous system, only lower than Alzheimer's disease. Early-onset Parkinson's disease (EPOD) refers to Parkinson's disease with initial symptoms appearing before the age of 50. EOPD is associated with certain genetic mutations and has distinct clinical features. This study reports a case of EOPD with mutations in both the PRKN and the APOB genes. The patient presented with the initial symptom of unstable walking at the age of 28, followed by bradykinesia, limb tremors, masked face, shuffling gait, and cogwheel rigidity in both upper limbs. The blood lipid test showed total cholesterol of 6.48 mmol/L and low-density lipoprotein cholesterol of 4.13 mmol/L. Genetic testing showed a deletion in exon 5 and a point mutation [c.850G>C(p.Gly284Arg)] in exon 7 of the PRKN gene, as well as a point mutation [c.10579C>T(p.Arg3527Trp)] in exon 26 of the APOB gene. Based on these clinical manifestations and examination results, the patient was diagnosed with EOPD. The compound heterozygous mutations in the PRKN gene, as well as the combined mutations in the PRKN and APOB genes, are both reported for the first time, expanding the spectrum of genetic mutations associated with EOPD.

Genetic and molecular architecture of familial hypercholesterolemia.

Atherosclerotic cardiovascular disease is the leading cause of death globally. Despite its important risk of premature atherosclerosis and cardiovascular disease, familial hypercholesterolemia (FH) is still largely underdiagnosed worldwide. It is one of the most frequently inherited diseases due to mutations, for autosomal dominant forms, in either of the LDLR, APOB, and PCSK9 genes or possibly a few mutations in the APOE gene and, for the rare autosomal forms, in the LDLRAP1 gene. The discovery of the genes implicated in the disease has largely helped to improve the diagnosis and treatment of FH from the LDLR by Brown and Goldstein, as well as the introduction of statins, to PCSK9 discovery in FH by Abifadel et al., and the very rapid availability of PCSK9 inhibitors. In the last two decades, major progress has been made in clinical and genetic diagnostic tools and the therapeutic arsenal against FH. Improving prevention, diagnosis, and treatment and making them more accessible to all patients will help reduce the lifelong burden of the disease.

Interplay of Atherogenic Particle Number and Particle Size and the Risk of Coronary Heart Disease.

BACKGROUND: We examined the interplay of apolipoprotein B (apoB) and LDL particle size, approximated by the LDL-cholesterol (LDL-C)/apoB ratio, on the risk of new-onset coronary heart disease (CHD). METHODS: Participants without cardiovascular disease from the UK Biobank (UKB; n = 308 182), the Women's Health Study (WHS; n = 26 204), and the Framingham Heart Study (FHS; n = 2839) were included. Multivariable Cox models were used to assess the relationship between apoB and LDL-C/apoB ratio and incidence of CHD (14 994 events). Our analyses were adjusted for age, sex (except WHS), HDL-cholesterol (HDL-C), systolic blood pressure, antihypertensive treatment, diabetes, and smoking. RESULTS: In all 3 studies, there was a strong positive correlation between apoB and LDL-C (correlation coefficients r = 0.80 or higher) and a weak inverse correlation of apoB with LDL-C/apoB ratio (-0.28 ≤ r ≤ -0.14). For all 3 cohorts, CHD risk was higher for higher levels of apoB. Upon multivariable adjustment, the association between apoB and new-onset CHD remained robust and statistically significant in all 3 cohorts with hazard ratios per 1 SD (95% CI): 1.24 (1.22-1.27), 1.33 (1.20-1.47), and 1.24 (1.09-1.42) for UKB, WHS, and FHS, respectively. However, the association between LDL-C/apoB and CHD was statistically significant only in the FHS cohort: 0.78 (0.64-0.94). CONCLUSIONS: Our analysis confirms that apoB is a strong risk factor for CHD. However, given the null association in 2 of the 3 studies, we cannot confirm that cholesterol-depleted LDL particles are substantially more atherogenic than cholesterol-replete particles. These results lend further support to routine measurement of apoB in clinical care.

Predictive Modeling and Structure Analysis of Genetic Variants in Familial Hypercholesterolemia: Implications for Diagnosis and Protein Interaction Studies.

PURPOSE OF REVIEW: Familial hypercholesterolemia (FH) is a hereditary condition characterized by elevated levels of low-density lipoprotein cholesterol (LDL-C), which increases the risk of cardiovascular disease if left untreated. This review aims to discuss the role of bioinformatics tools in evaluating the pathogenicity of missense variants associated with FH. Specifically, it highlights the use of predictive models based on protein sequence, structure, evolutionary conservation, and other relevant features in identifying genetic variants within LDLR, APOB, and PCSK9 genes that contribute to FH. RECENT FINDINGS: In recent years, various bioinformatics tools have emerged as valuable resources for analyzing missense variants in FH-related genes. Tools such as REVEL, Varity, and CADD use diverse computational approaches to predict the impact of genetic variants on protein function. These tools consider factors such as sequence conservation, structural alterations, and receptor binding to aid in interpreting the pathogenicity of identified missense variants. While these predictive models offer valuable insights, the accuracy of predictions can vary, especially for proteins with unique characteristics that might not be well represented in the databases used for training. This review emphasizes the significance of utilizing bioinformatics tools for assessing the pathogenicity of FH-associated missense variants. Despite their contributions, a definitive diagnosis of a genetic variant necessitates functional validation through in vitro characterization or cascade screening. This step ensures the precise identification of FH-related variants, leading to more accurate diagnoses. Integrating genetic data with reliable bioinformatics predictions and functional validation can enhance our understanding of the genetic basis of FH, enabling improved diagnosis, risk stratification, and personalized treatment for affected individuals. The comprehensive approach outlined in this review promises to advance the management of this inherited disorder, potentially leading to better health outcomes for those affected by FH.

Mass-spectrometric analysis of APOB polymorphism rs1042031 (G/T) and its influence on serum proteome of coronary artery disease patients: genetic-derived proteomics consequences.

Genetic polymorphisms of apolipoprotein B gene (APOB) may result into serum proteomic perturbance in Coronary Artery Disease (CAD). The current case-control cohort of Pakistani subjects was designed to analyze the genetic influence of APOB rs1042031, (G/T) genotype on serum proteome. Subjects were categorized into two groups: CAD patients (n = 480) and healthy individuals (n = 220). For genotyping, tetra ARMS-PCR was carried out and validated through sequencing, whereas LC/MS-based proteomic analysis of serum samples was performed through label-free quantification. In initial step of genotyping, the frequencies of each genotype GG, GT, and TT were 70%, 27%, and 30% in CAD patients, while in control group, the subjects were 52%, 43%, and 5%, respectively, in CAD patients. The genotypic frequencies in patients vs. control groups found significantly different (p = 0.004), and a strong association of dominant alleles GG with the CAD was observed in both dominant (OR: 2.4 (1.71-3.34), p = 0.001) and allelic genetic models (OR: 2.0 (1.45-2.86), p = 0.001). In second step of label-free quantitation, a total of 40 significant proteins were found with altered expression in CAD patients. The enriched Gene Ontology (GO) terms of molecular functions and pathways of these protein showed upregulated pathways as follows: chylomicron remodeling and assembly, complement cascade activation, plasma lipoprotein assembly, apolipoprotein-A receptor binding, and metabolism of fat-soluble vitamins in G allele carrier of rs1042031 (G > T) vs. mutant T-allele carriers. This study provides better understanding of CAD pathobiology by proteogenomics of APOB. It evidences the influence of APOB rs1042031-dominant (GG) genotype with CAD patients.

Low LDL Cholesterol Is Not an Independent Risk Factor for Hepatic Steatosis.

BACKGROUND: Genetic mutations causing defective VLDL secretion and low LDL cholesterol are associated with hepatic steatosis and nonalcoholic fatty liver disease (NAFLD). AIMS: Determine if low LDL cholesterol (< 5th percentile) was an independent predictor of hepatic steatosis. METHODS: Secondary data analysis of the Dallas Heart study (an urban, multiethnic, probability-based sample), we defined hepatic steatosis utilizing intrahepatic triglyceride (IHTG) analyzed using magnetic resonance spectroscopy in conjunction and available demographic, serological and genetic information. We exclude patients on lipid lowering medications. RESULTS: Of the 2094 subjects that met our exclusion criteria, 86 had a low LDL cholesterol, of whom 19 (22%) exhibited hepatic steatosis. After matching for age, sex, BMI, and alcohol consumption, low LDL cholesterol was not a risk factor for hepatic steatosis compared to those with normal (50-180 mg/dL) or high (> 180 mg/dL) LDL. When analyzed as a continuous variable, we observed lower IHTG in the low LDL group compared to the normal or high LDL groups (2.2%, 3.5%, 4.6%; all pairwise comparisons p < 0.001). Subjects with both hepatic steatosis and low LDL cholesterol exhibited a more favorable lipid profile but similar insulin resistance and hepatic fibrosis risk compared to other subjects with hepatic steatosis. The distribution of variant alleles associated with NAFLD, including PNPLA3, GCKR, and MTTP was indistinguishable between subjects with hepatic steatosis and low versus high LDL cholesterol. CONCLUSION: These findings suggest that low serum LDL levels are not a useful predictor of hepatic steatosis and NAFLD. Moreover, subjects with low LDL exhibit a more favorable lipid profile and lower IHTG.

Prenatal lipopolysaccharide exposure induces anxiety-like behaviour in male mouse offspring and aberrant glial differentiation of embryonic neural stem cells.

BACKGROUND: Prenatal infection has been implicated in the development of neuropsychiatric disorders in children. We hypothesised that exposure to lipopolysaccharide during prenatal development could induce anxiety-like behaviour and sensorineural hearing loss in offspring, as well as disrupt neural differentiation during embryonic neural development. METHODS: We simulated prenatal infection in FVB mice and mouse embryonic stem cell (ESC) lines, specifically 46C and E14Tg2a, through lipopolysaccharide treatment. Gene expression profiling analyses and behavioural tests were utilized to study the effects of lipopolysaccharide on the offspring and alterations in toll-like receptor (TLR) 2-positive and TLR4-positive cells during neural differentiation in the ESCs. RESULTS: Exposure to lipopolysaccharide (25 µg/kg) on gestation day 9 resulted in anxiety-like behaviour specifically in male offspring, while no effects were detected in female offspring. We also found significant increases in the expression of GFAP and CNPase, as well as higher numbers of GFAP + astrocytes and O4+ oligodendrocytes in the prefrontal cortex of male offspring. Furthermore, increased scores for genes related to oligodendrocyte and lipid metabolism, particularly ApoE, were observed in the prefrontal cortex regions. Upon exposure to lipopolysaccharide during the ESC-to-neural stem cell (NSC) transition, Tuj1, Map2, Gfap, O4, and Oligo2 mRNA levels increased in the differentiated neural cells on day 14. In vitro experiments demonstrated that lipopolysaccharide exposure induced inflammatory responses, as evidenced by increased expression of IL1b and ApoB mRNA. CONCLUSIONS: Our findings suggest that prenatal infection at different stages of neural differentiation may result in distinct disturbances in neural differentiation during ESC-NSC transitions. Furthermore, early prenatal challenges with lipopolysaccharide selectively induce anxiety-like behaviour in male offspring. This behaviour may be attributed to the abnormal differentiation of astrocytes and oligodendrocytes in the brain, potentially mediated by ApoB/E signalling pathways in response to inflammatory stimuli.

Screening and verifying the mutations in the LDLR and APOB genes in a Chinese family with familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is an autosomal dominant genetic disorder. The primary objective of this study was to identify the major pathogenic mutations in a Chinese family with FH. METHODS: Whole-genome sequencing (WGS) was used to identify variants of FH-related genes, including low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9). Bioinformatics software was used to predict signal peptides, transmembrane structures, and spatial construction information of the mutated sequences. Western blotting was performed on the mutant protein to determine the presence of the major structural domains of the LDLR. The PCSK9 and APOB genes were screened and analyzed. Moreover, the proband and his brother were treated with a PCSK9 inhibitor for 1 year, and the effect of the treatment on lipid levels was assessed. RESULTS: WGS revealed two potentially pathogenic mutations in the LDLR gene. One was a novel mutation, c.497delinsGGATCCCCCAGCTGCATCCCCCAG (p. Ala166fs), and the other was a known pathogenic mutation, c.2054C>T (p. Pro685Leu). Bioinformatics prediction and in vitro experiments revealed that the novel mutation could not be expressed on the cell membrane. Numerous gene variants were identified in the APOB gene that may have a significant impact on the family members with FH. Thus, it is suggested that the severe manifestation of FH in the proband primarily resulted from the cumulative genetic effects of variants in both LDLR and APOB. However, a subsequent study indicated that treatment with a PCSK9 inhibitor (Evolocumab) did not significantly reduce the blood lipid levels in the proband or his brother. CONCLUSIONS: The cumulative effect of LDLR and APOB variants was the primary cause of elevated blood lipid levels in this family. However, PCSK9 inhibitor therapy did not appear to be beneficial for the proband. This study emphasizes the importance of genetic testing in determining the most suitable treatment options for patients with FH.

The LDL-C/ApoB ratio predicts cardiovascular and all-cause mortality in the general population.

BACKGROUND: Generally, low-density lipoprotein (LDL) particle size can be inferred from the LDL cholesterol concentration to total apolipoprotein B concentration ratio (LDL-C/ApoB ratio, hereinafter called LAR), which is a good predictor of cardiovascular disease. However, the predictive ability of LAR for mortality risk in the general population is still unclear. This study aimed to explore the association between LAR and cardiovascular as well as all-cause mortality among American adults. METHODS: The present study was a secondary analysis of existing data from the National Health and Nutrition Examination Survey (NHANES). The final analysis included 12,440 participants from 2005 to 2014. Survival differences between groups were visualized using Kaplan‒Meier curves and the log-rank test. The association of LAR with cardiovascular and all-cause mortality was evaluated using multivariate Cox regression and restricted cubic spline analysis. Age, sex, coronary artery disease, diabetes, lipid-lowering medication use and hypertriglyceridemia were analyzed in subgroup analyses. RESULTS: The median age in the study cohort was 46.0 years [interquartile range (IQR): 31.0-62.0], and 6,034 (48.5%) participants were male. During the follow-up period, there were 872 (7.0%) all-cause deaths and 150 (1.2%) cardiovascular deaths. Compared with individuals without cardiovascular events, those who experienced cardiovascular deaths had a lower LAR (1.13 vs. 1.25) (P < 0.001). The adjusted Cox regression model indicated that lower LAR was an independent risk factor for both cardiovascular [hazard ratio (HR) = 0.304, 95% confidence interval (CI): 0.114-0.812] and all-cause mortality (HR = 0.408, 95% CI: 0.270-0.617). Moreover, a significant age interaction was observed (P for interaction < 0.05), and there was a strong association between LAR and mortality among participants over 65 years of age. Further analysis showed an inverse association between LAR and both cardiovascular and all-cause mortality. CONCLUSIONS: LAR can independently predict cardiovascular and all-cause mortality in the general population.

Mechanism of the Regulation of Plasma Cholesterol Levels by PI(4,5)P2.

Elevated low-density lipoprotein (LDL) cholesterol (LDLc) is one of the most well-established risk factors for cardiovascular disease, while high levels of high-density lipoprotein (HDL) cholesterol (HDLc) have been associated with protection from cardiovascular disease. Cardiovascular disease remains one of the leading causes of death worldwide; thus it is important to understand mechanisms that impact LDLc and HDLc metabolism. In this chapter, we will discuss molecular processes by which phosphatidylinositol-(4,5)-bisphosphate, PI(4,5)P2, is thought to modulate LDLc or HDLc. Section 1 will provide an overview of cholesterol in the circulation, discussing processes that modulate the various forms of lipoproteins (LDL and HDL) carrying cholesterol. Section 2 will describe how a PI(4,5)P2 phosphatase, transmembrane protein 55B (TMEM55B), impacts circulating LDLc levels through its ability to regulate lysosomal decay of the low-density lipoprotein receptor (LDLR), the primary receptor for hepatic LDL uptake. Section 3 will discuss how PI(4,5)P2 interacts with apolipoprotein A-I (apoA1), the key apolipoprotein on HDL. In addition to direct mechanisms of PI(4,5)P2 action on circulating cholesterol, Sect. 4 will review how PI(4,5)P2 may indirectly impact LDLc and HDLc by affecting insulin action. Last, as cholesterol is controlled through intricate negative feedback loops, Sect. 5 will describe how PI(4,5)P2 is regulated by cholesterol.

Identification and Functional Analysis of APOB Variants in a Cohort of Hypercholesterolemic Patients.

Mutations in APOB are the second most frequent cause of familial hypercholesterolemia (FH). APOB is highly polymorphic, and many variants are benign or of uncertain significance, so functional analysis is necessary to ascertain their pathogenicity. Our aim was to identify and characterize APOB variants in patients with hypercholesterolemia. Index patients (n = 825) with clinically suspected FH were analyzed using next-generation sequencing. In total, 40% of the patients presented a variant in LDLR, APOB, PCSK9 or LDLRAP1, with 12% of the variants in APOB. These variants showed frequencies in the general population lower than 0.5% and were classified as damaging and/or probably damaging by 3 or more predictors of pathogenicity. The variants c.10030A>G;p.(Lys3344Glu) and c.11401T>A;p.(Ser3801Thr) were characterized. The p.(Lys3344Glu) variant co-segregated with high low-density lipoprotein (LDL)-cholesterol in 2 families studied. LDL isolated from apoB p.(Lys3344Glu) heterozygous patients showed reduced ability to compete with fluorescently-labelled LDL for cellular binding and uptake compared with control LDL and was markedly deficient in supporting U937 cell proliferation. LDL that was carrying apoB p.(Ser3801Thr) was not defective in competing with control LDL for cellular binding and uptake. We conclude that the apoB p.(Lys3344Glu) variant is defective in the interaction with the LDL receptor and is causative of FH, whereas the apoB p.(Ser3801Thr) variant is benign.

The Correlation of Apolipoprotein B with Alterations in Specific Fat Depots Content in Adults.

Body mass index (BMI) and blood biomarkers are not enough to predict cardiovascular disease risk. Apolipoprotein B was identified to be associated with cardiovascular disease (CVD) progression. The Dual-energy X-ray Absorption (DXA) results could be considered as a predictor for cardiovascular disease in a more refined way based on fat distribution. The prediction of CVD risk by simple indicators still cannot meet clinical needs. The association of ApoB with specific fat depot features remains to be explored to better co-predict cardiovascular disease risk. An amount of 5997 adults from National Health and Nutrition Examination Survey (NHANES) were enrolled. Their demographic information, baseline clinical condition, blood examination, and DXA physical examination data were collected. Multivariate regression was used to assess the correlation between ApoB and site-specific fat characteristics through different adjusted models. Smooth curve fittings and threshold analysis were used to discover the turning points with 95% confidence intervals. ApoB is positively correlated with arms percent fat, legs percent fat, trunk percent fat, android percent fat, gynoid percent fat, arm circumference and waist circumference after adjustment with covariates for age, gender, race, hypertension, diabetes, hyperlipidemia, coronary heart disease, smoking status and vigorous work activity. The smooth curve fitting and threshold analysis also showed that depot-specific fat had lower turning points of ApoB in both males and females within the normal reference range of ApoB. Meanwhile, females have a lower increase in ApoB per 1% total percent fat and android percent fat than males before the turning points, while females have a higher growth of ApoB per 1% gynoid percent fat than males. The combined specific fat-depot DXA and ApoB analysis could indicate the risk of CVD in advance of lipid biomarkers or DXA alone.