Apolipoprotein C-III Research Articles

Established and Emerging Lipid-Lowering Drugs for Primary and Secondary Cardiovascular Prevention.

Despite treatment with statins, patients with elevated low-density lipoprotein cholesterol (LDL-C) and triglycerides remain at increased risk for adverse cardiovascular events. Consequently, novel pharmaceutical drugs have been developed to control and modify the composition of blood lipids to ultimately prevent fatal cardiovascular events in patients with dyslipidaemia. This article reviews established and emerging lipid-lowering drugs regarding their mechanism of action, development stage, ongoing clinical trials, side effects, effect on blood lipids and reduction in cardiovascular morbidity and mortality. We conducted a keyword search to identify studies on established and emerging lipid modifying drugs. Results were summarized in a narrative overview. Established pharmaceutical treatment options include the Niemann-Pick-C1 like-1 protein (NPC1L1) inhibitor ezetimibe, the protein convertase subtilisin-kexin type 9 (PCSK9) inhibitors alirocumab and evolocumab, fibrates as peroxisome proliferator receptor alpha (PPAR-α) activators, and the omega-3 fatty acid icosapent ethyl. Statins are recommended as the first-line therapy for primary and secondary cardiovascular prevention in patients with hypercholesterinaemia and hypertriglyceridemia. For secondary prevention in hypercholesterinaemia, second-line options such as statin add-on or statin-intolerant treatments are ezetimibe, alirocumab and evolocumab. For secondary prevention in hypertriglyceridemia, second-line options such as statin add-on or statin-intolerant treatments are icosapent ethyl and fenofibrate. Robust data for these add-on therapeutics in primary cardiovascular prevention remains scarce. Recent biotechnological advances have led to the development of innovative small molecules (bempedoic acid, lomitapide, pemafibrate, docosapentaenoic and eicosapentaenoic acid), antibodies (evinacumab), antisense oligonucleotides (mipomersen, volanesorsen, pelcarsen, olezarsen), small interfering RNA (inclisiran, olpasiran), and gene therapies for patients with dyslipidemia. These molecules specifically target new cellular pathways, such as the adenosine triphosphate-citrate lyase (bempedoic acid), PCSK9 (inclisiran), angiopoietin-like 3 (ANGPTL3: evinacumab), microsomal triglyceride transfer protein (MTP: lomitapide), apolipoprotein B-100 (ApoB-100: mipomersen), apolipoprotein C-III (ApoC-III: volanesorsen, olezarsen), and lipoprotein (a) (Lp(a): pelcarsen, olpasiran). The authors are hopeful that the development of new treatment modalities alongside new therapeutic targets will further reduce patients' risk of adverse cardiovascular events. Apart from statins, data on new drugs' use in primary cardiovascular prevention remain scarce. For their swift adoption into clinical routine, these treatments must demonstrate safety and efficacy as well as cost-effectiveness in randomized cardiovascular outcome trials.

Protein Corona of Anionic Fluid-Phase Liposomes Compromises Their Integrity Rather than Uptake by Cells.

Despite the undisputable role of the protein corona in the biointeractions of liposome drug carriers, the field suffers from a lack of knowledge regarding the patterns of protein deposition on lipid surfaces with different compositions. Here, we investigated the protein coronas formed on liposomes of basic compositions containing combinations of egg phosphatidylcholine (PC), palmitoyloleoyl phosphatidylglycerol (POPG), and cholesterol. Liposome-protein complexes isolated by size-exclusion chromatography were delipidated and analyzed using label-free LC-MS/MS. The addition of the anionic lipid and cholesterol both affected the relative protein abundances (and not the total bound proteins) in the coronas. Highly anionic liposomes, namely those containing 40% POPG, carried corona enriched with cationic proteins (apolipoprotein C1, beta-2-glycoprotein 1, and cathelicidins) and were the least stable in the calcein release assay. Cholesterol improved the liposome stability in the plasma. However, the differences in the corona compositions had little effect on the liposome uptake by endothelial (EA.hy926) and phagocytic cells in the culture (U937) or ex vivo (blood-derived monocytes and neutrophils). The findings emphasize that the effect of protein corona on the performance of the liposomes as drug carriers occurs through compromising particle stability rather than interfering with cellular uptake.

Lipids and apolipoproteins C-III and E among treatment-naïve and treatment-experienced persons with HIV in Nigeria.

Dyslipidaemia is a known cause of cardiovascular mortality. Persons living with HIV are at high risk of developing cardiovascular disease due to lipid metabolism disorders associated with HIV or its therapy. This study evaluated concentrations of lipoproteins and apolipoprotein C-III and E, as a way of assessing cardiometabolic risks among HIV patients. We enrolled 50 HIV-negative persons and 100 HIV-positive patients, 50 on antiretroviral therapy (ART) and 50 treatment-naïve persons, from the Central Hospital and the Stella Obasanjo Hospital, Benin City, Edo State, Nigeria, between May 2015 and November 2015. Participants with a history of metabolic abnormalities were excluded. Apolipoproteins were assessed by enzyme-linked immunosorbent assay, while lipids were measured by spectrophotometry. There were significant abnormalities in the lipid profile of patients with HIV. Triglycerides levels of HIV patients (ART-naïve: 1.44 ± 0.65 mmol/L; p < 0.001 and ART-experienced: 1.49 ± 0.70 mmol/L; p = 0.001) were significantly higher than among controls (0.95 ± 0.54 mmol/L). HIV patients had higher concentrations of apolipoprotein C-III than controls (p < 0.001) and higher low-density lipoprotein cholesterol levels (treatment-naïve: 2.83 mmol/L and ART-experienced patients: 3.59 mmol/L) than controls (2.50 mmol/L; p = 0.003). Conversely, HIV patients had significantly lowered high-density lipoprotein cholesterol levels compared to controls (p < 0.001). Dyslipidaemia was observed among HIV participants, irrespective of their ART experience. Therefore, it is crucial that the lipids of HIV patients be closely monitored to enable early intervention and decrease cardiovascular death. This study affirms that dyslipidemia is a complication of HIV or the prolonged use of ART.

Triglyceride-Rich Lipoprotein Metabolism: Key Regulators of Their Flux

The residual risk for arteriosclerotic cardiovascular disease after optimal statin treatment may amount to 50% and is the consequence of both immunological and lipid disturbances. Regarding the lipid disturbances, the role of triglyceride-rich lipoproteins (TRLs) and their remnants has come to the forefront in the past decade. Triglycerides (TGs) stand as markers of the remnants of the catabolism of TRLs that tend to contain twice as much cholesterol as compared to LDL. The accumulation of circulating TRLs and their partially lipolyzed derivatives, known as “remnants”, is caused mainly by ineffective triglyceride catabolism. These cholesterol-enriched remnant particles are hypothesized to contribute to atherogenesis. The aim of the present narrative review is to briefly summarize the main pathways of TRL metabolism, bringing to the forefront the newly discovered role of apolipoproteins, the key physiological function of lipoprotein lipase and its main regulators, the importance of the fluxes of these particles in the post-prandial period, their catabolic rates and the role of apo CIII and angiopoietin-like proteins in the partition of TRLs during the fast-fed cycle. Finally, we provide a succinct summary of the new and old therapeutic armamentarium and the outcomes of key current trials with a final outlook on the different methodological approaches to measuring TRL remnants, still in search of the gold standard.

Protective Association of APOC1/rs4420638 with Risk of Obesity: A case-control Study in Portuguese Children

The association of the rs4420638 polymorphism, near the APOC1 gene, was examined with the risk of obesity among Portuguese children. A sample of 446 Portuguese individuals (231 boys and 215 girls) of European descent, aged 3.2 to 13.7 years old (mean age: 7.98 years), were selected to conduct a case-control study. Body mass index (BMI), BMI Z-scores, and waist circumference were calculated. Genotyping was performed by real time PCR using a pre-designed TaqMan probe. Logistic regression and the nonparametric Mann-Whitney test were used to test the associations. The association results revealed a significant protective effect from the minor G-allele of SNP rs4420638 against obesity, with an odds ratio (OR) of 0.619 (95% CI 0.421–0.913; p = 0.0155) in the additive model, and OR of 0.587 (95% CI 0.383-0.9; p = 0.0145) in the dominant model. Moreover, comparing genotype groups (AA vs. AG + GG), significantly lower values (p < 0.05) for the anthropometric traits weight, height, BMI, BMI Z-score and waist circumference, were observed in the carriers of allele G. The present study provides further evidence for the APOE/APOC1 candidate-region association with the risk of obesity. This was the first study to describe the protective association of the rs4420638 minor G-allele against obesity in childhood exclusively.

Apo CIII Proteoforms, Plasma Lipids, and Cardiovascular Risk in MESA.

Apo CIII (apolipoprotein CIII) is an important regulator of triglyceride metabolism and was associated with cardiovascular risk in several cohorts. It is present in 4 major proteoforms, a native peptide (CIII0a), and glycosylated proteoforms with zero (CIII0b), 1 (CIII1, most abundant), or 2 (CIII2) sialic acids, which may differentially modify lipoprotein metabolism. We studied the relationships of these proteoforms with plasma lipids and cardiovascular risk. Apo CIII proteoforms were measured by mass spectrometry immunoassay in baseline plasma samples of 5791 participants of Multi-Ethnic Study of Atherosclerosis, an observational community-based cohort. Standard plasma lipids were collected for up to 16 years and cardiovascular events (myocardial infarction, resuscitated cardiac arrest, or stroke) were adjudicated for up to 17 years. Apo CIII proteoform composition differed by age, sex, race and ethnicity, body mass index, and fasting glucose. Notably, CIII1 was lower in older participants, men and Black and Chinese (versus White) participants, and higher in obesity and diabetes. In contrast, CIII2 was higher in older participants, men, Black, and Chinese persons, and lower in Hispanic individuals and obesity. Higher CIII2 to CIII1 ratio (CIII2/III1) was associated with lower triglycerides and higher HDL (high-density lipoprotein) in cross-sectional and longitudinal models, independently of clinical and demographic risk factors and total apo CIII. The associations of CIII0a/III1 and CIII0b/III1 with plasma lipids were weaker and varied through cross-sectional and longitudinal analyses. Total apo CIII and CIII2/III1 were positively associated with cardiovascular disease risk (n=669 events, hazard ratios, 1.14 [95% CI, 1.04-1.25] and 1.21 [1.11-1.31], respectively); however, the associations were attenuated after adjustment for clinical and demographic characteristics (1.07 [0.98-1.16]; 1.07 [0.97-1.17]). In contrast, CIII0b/III1 was inversely associated with cardiovascular disease risk even after full adjustment including plasma lipids (0.86 [0.79-0.93]). Our data indicate differences in clinical and demographic relationships of apo CIII proteoforms, and highlight the importance of apo CIII proteoform composition in predicting future lipid patterns and cardiovascular disease risk.

#5795 THE APOPROTEIN E (APOE) POLYMORPHISM AND PROPROTEIN CONVERTASE SUBTILISIN KEXIN 9 (PCSK9) IN HEMODIALYSIS (HD) PATIENTS

Abstract Background and Aims The apoE polymorphism and PCSK9 play an important role in lipid metabolism in healthy subjects, however, its role in HD patients remains unclear. We investigated the apoE polymorphism and PCSK9 as well as a lipid profile to clarify the impact of these factors on prognosis in HD patients. We also examined the association of cardiovascular (CVD) events in dead HD patients and clinical features. Method HD patients (n = 296, m/f; 207/89, DM; 152, age; 69.8±12.1, HD duration; 68.7±72.0 months) were subjected to this study. Written informed consent was obtained from each patient. Of these patients 85 subjects (m/f; 61/24, DM; 54, HD duration; 98.6±53.5 months) died during this study (from June 2011 to December 2022). Blood samples were collected to analyze the apoE genotypes by the invader method, serum concentrations of PCSK9-heterodimers and PCSK9-free fragments were measured using ELISA (BML Co. Ltd., Tokyo, Japan) and serum concentrations of apoA1, apoA2, apoB, apo C2, apoC3 and apoE were estimated using turbidimetric immunoassay. For the death cases we used multivariable logistic regression to control for the potentially confounding roles of type 2 diabetes mellitus (DM), apoE genotypes, and serum concentrations of PCSK9-heterodimers, PCSK9-free segments, apoA1, apoA2, apoB, apo C2, apoC3 and apoE. Survival probabilities in dead HD patients with CVD events according to the apoE genotypes were analyzed using the Kaplan-Meier curves. A p value less than 0.05 was considered statistically significant. Results The spoE allele frequencies in HD patients (n = 296) were ɛ2; 0.044, ɛ3; 0.870 and ɛ4; 0.086, whereas those in Japanese healthy controls were ɛ2; 0.036, ɛ3; 0.848 and ɛ4; 0.116 (Eto M., et al. Clin Genet 30:422-427, 1986.), demonstrating the ɛ2 frequency in HD patients had a trend to be higher than that in Japanese healthy controls (p = 0.096). The serum concentrations of PCSK9-heterodimers and PCSK9-free fragments in female HD patients (n = 89, 227.0±88.0 ng/ml and 41.9±19.1 ng/ml, respectively) were significantly higher than those in male HD patients (n = 207, 195.9±70.3 ng/ml, p = 0.001, and 35.8±15.3 ng/ml, p&amp;lt;0.004, respectively) . The serum concentrations of PCSK9-heterodimers in HD patients with DM (n = 152); 213.8±77.6 ng/ml showed a trend to be higher than those in HD patients without DM (n = 144); 196.3±76.1 ng/ml (p = 0.05). The multivariable logistic regression analysis demonstrated the serum concentration of apoA1 and apoE polymorphism showed statistically significant impact on CVD events in dead HD patients (Table 1). The Kaplan-Meier analysis revealed the apoE polymorphism had a significant impact on the survival probability in dead HD patients with CVD events (Figure 1). Conclusion Recent studies reported the association between apoE2 and renal insufficiency in Japanese type2 DM. ApoE2 may be one of the attributable factors that lead to the end stage kidney disease. PCSK9-heterodimers bind to LDL cholesterol receptors (LDLr) and prevent LDLr from shuttling back to the surface and instead target it for degradation, however, PCSK9-free segments have weaker effects to bind to LDLr. Significance of higher serum concentrations of PCSK9-heterodimers andPCSK9-free fragments in female HD patients than male HD patients depends on future investigation. ApoE2 and the serum concentration of apoA1 contribute to CVD events. The prognosis of the HD patients with apoE2 or apoE4 were poorer than that with apoE3/3. The apoE polymorphism and PCSK9 may be key factors in lipid metabolism as well as prognosis of HD patients.

Primary disorders of lipid metabolism: their place in current dyslipidemia guidelines and treatment innovations

According to current guidelines, the selection and intensity of lipid-effective therapies are based on the risk to be treated. The sole clinical categories of primary and secondary prevention of cardiovascular diseases result in over- and under-treatment, which may be acontributory cause of incomplete implementation of current guidelines in everyday practice. For the extent of benefit in cardiovascular outcome studies with lipid-lowering drugs, the importance of dyslipdemia for the pathogenesis of atherosclerosis-related diseases is crucial. Primary lipid metabolism disorders are characterized by life-long increased exposure to atherogenic lipoproteins. This article describes the relevance of new data for low density lipoprotein-effective therapy: inhibition of proprotein convertase subtilisin/kexin type9 (PCSK9), adenosine triphosphate (ATP) citrate lyase with bempedoic acid, and ANGPTL3 with special consideration of primary lipid metabolism disorders, which are insufficiently taken into account, or not taken into account at all, in current guidelines. This is due to their apparently low prevalence rate and thus the lack of large outcome studies. The authors also discuss the consequences of increased lipoprotein(a), which cannot be sufficiently reduced until the ongoing intervention studies examining antisense oligonucleotides and small interfering RNA (siRNA) against apolipoprotein(a) are completed. Another challenge in practice is the treatment of rare, massive hypertriglyceridemia, especially with the aim of preventing pancreatitis. For this purpose, the apolipoprotein C3 (ApoC3) antisense oligonucleotide volenasorsen is available, which binds to the mRNA for ApoC3 and lowers triglycerides by around three quarters.

Levels of ANGPTL3 and characterization of other circulating cholesterol-related factors in high-grade serous ovarian cancers.

e17583 Background: Cancer cells require important amounts of cholesterol to sustain their growth. High-grade serous ovarian carcinomas (HGSOC), as an aggressive form of ovarian cancer, are no exception. Mechanisms allowing HGSOC to secure their lipid supplies are not yet fully elucidated. Recent years have highlighted ANGPTL3, PCSK9 and Apo CIII as key players in lipid metabolism. To date, impact of HGSOC on these key lipid-regulating factors is scantly documented. Herein, we compared ANGPTL3, PCSK9, Apo CIII and Lp(a) levels in women with HGSOC versus benign ovarian lesion (BOL) to better understand lipid metabolism in HGSOC. Methods: Plasma samples from 31 women with a HGSOC and 40 women with a BOL were assayed for ANGPTL3, PCSK9, and Apo CIII levels by ELISA. The lipid panel, Apo B and Lp(a) levels were measured on a Roche Modular analytical platform. Results: Higher levels of ANGPTL3 was observed in HGSOC (84 ng/ml, SD ±29 ng/ml, n = 31) vs. BOL (67 ng/ml, SD ±31 ng/ml, n = 40); HGSOC vs BOL p = 0.019. Receiver operating characteristic (ROC) curve analyses for ANGPTL3 combined with age indicated an area under curve of 67.7% (p = 0.005). Partial correlations indicated associations between the lipid panel and ANGPTL3, but only for BOL. Conclusions: In this cohort of 71 women, ANGPTL3 levels were higher in patients with HGSOC. This finding requires further validation in a larger cohort of HGSOC patients.

Inverse association between apolipoprotein C-II and cardiovascular mortality: role of lipoprotein lipase activity modulation.

Apolipoprotein C-II (ApoC-II) is thought to activate lipoprotein lipase (LPL) and is therefore a possible target for treating hypertriglyceridemia. Its relationship with cardiovascular risk has not been investigated in large-scale epidemiologic studies, particularly allowing for apolipoprotein C-III (ApoC-III), an LPL antagonist. Furthermore, the exact mechanism of ApoC-II-mediated LPL activation is unclear. ApoC-II was measured in 3141 LURIC participants of which 590 died from cardiovascular diseases during a median (inter-quartile range) follow-up of 9.9 (8.7-10.7) years. Apolipoprotein C-II-mediated activation of the glycosylphosphatidylinositol high-density lipoprotein binding protein 1 (GPIHBP1)-LPL complex was studied using enzymatic activity assays with fluorometric lipase and very low-density lipoprotein (VLDL) substrates. The mean ApoC-II concentration was 4.5 (2.4) mg/dL. The relationship of ApoC-II quintiles with cardiovascular mortality exhibited a trend toward an inverse J-shape, with the highest risk in the first (lowest) quintile and lowest risk in the middle quintile. Compared with the first quintile, all other quintiles were associated with decreased cardiovascular mortality after multivariate adjustments including ApoC-III as a covariate (all P < 0.05). In experiments using fluorometric substrate-based lipase assays, there was a bell-shaped relationship for the effect of ApoC-II on GPIHBP1-LPL activity when exogenous ApoC-II was added. In ApoC-II-containing VLDL substrate-based lipase assays, GPIHBP1-LPL enzymatic activity was almost completely blocked by a neutralizing anti-ApoC-II antibody. The present epidemiologic data suggest that increasing low circulating ApoC-II levels may reduce cardiovascular risk. This conclusion is supported by the observation that optimal ApoC-II concentrations are required for maximal GPIHBP1-LPL enzymatic activity.

Plasma concentrations of apolipoproteins C3 and C2 do not explain differences in insulin-stimulated endothelial-bound lipoprotein lipase activity in insulin resistant humans

Elevated circulating triglycerides (i.e., dyslipidemia) is a hallmark of insulin resistance and is generally caused by decrease in lipoprotein lipase (LPL) activity. LPL hydrolyzes triglycerides (TG) into free fatty acids in plasma for use and/or storage in tissues (i.e., adipose, skeletal muscle). Plasma apolipoproteins (Apos) C3 and C2 interact with LPL to modulate its function by activating or inhibiting LPL. Previous research shows, in the metabolic environment of insulin resistance, the concentration of ApoC3 is increased in plasma while that of ApoC2 is decreased. Thus, Apos are considered key factors in regulating plasma lipid metabolism via modulation of LPL function. The purpose of this study was to investigate the concentrations of ApoC3 and ApoC2 in plasma and along endothelial-bound LPL activity in insulin resistant and healthy/non-insulin resistant individuals. We evaluated insulin resistance (IR)/insulin sensitivity (IS) using an oral glucose tolerance test (i.e., Matsuda index calculation) in subjects between ages 19 and 45 years old. Subjects were placed in the following two groups: 1) IR, if Matsuda index &lt;4.0 (N=6; 4 males, 2 females; BMI: 23-45 kg/m2), or 2) IS, if Matsuda index &gt;7.0 (N=11, 9 males, 2 females; BMI: 18-26 kg/m2). Subjects received an intravenous insulin infusion (0.5 mU/kg/min) for 30 minutes to resemble increased postprandial plasma insulin response. To release whole-body endothelial-bound LPL, subjects received an injection of intravenous heparin (75 UI/kg). Plasma samples were collected 10 minutes after the heparin infusion and analyzed for LPL concentration and activity, and ApoC3 and ApoC2 concentrations using ELISA. Differences between IS and IR subjects were determined using a t-test, and the P value was set at P &lt; 0.05. Plasma LPL concentrations were not different between groups (IR = 457 ± 17 ng/ml, IS = 453 ± 27 ng/ml, P &gt; 0.05), but plasma LPL activity was higher in the IR subjects (IR = 665 ± 113 nmol/min/ml, IS = 365 ± 59 nmol/min/ml, P = 0.02). IR subjects had higher concentrations of plasma ApoC3 (IR = 3.6 ± 0.5 mg/dl, IS = 2.7 ± 0.2 mg/dl, P=0.03) but ApoC2 was not different between groups (IR = 0.15 ± 0.03 mg/dl, IS = 0.11 ± 0.01 mg/dl, P = 0.11). The ratio of circulating LPL to circulating ApoC3 (IR = 145 ± 22, IS = 176 ± 15) or circulating ApocC2 (IR = 4104 ± 844, IS = 4391 ± 483) were not different between groups (P &gt; 0.05). We conclude that interactions of LPL with APOC3 and ApoC2 may not be main determinants regulating differential whole-body plasma LPL activity under plasma insulin-stimulated conditions in insulin resistant humans. American Diabetes Association Grant #7-12-CT-40 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

An Unexpected Diagnosis of MAGT1 Deficiency in a Patient with CVID-like Features, Molluscum Contagiosum and Atopy

Case DescriptionA 6-year-old boy presented to the immunology clinic with recurrent infections. He started to have recurrent otitis media at the age of 18 months. He also had multiple sinus infections and 3–4 episodes of pneumonia. Immunologic evaluation revealed an IgG of 498 (ref 608–1229 mg/dL), an IgA of 20.8 (ref 33–200 mg/dL) and an impaired response to the Streptococcus pneumoniae vaccine. T and B lymphocyte counts were normal. He was started on subcutaneous immunoglobulin replacement therapy after which his IgG level normalized and his frequency of sinopulmonary infections improved. He also has a history of eczema, chronic cough and environmental allergies for which he receives allergen-specific subcutaneous immunotherapy in addition to treatment with an inhaled corticosteroid and omalizumab. The patient also had persistent skin warts on his hands and extensive molluscum contagiosum lesions. He underwent targeted genetic testing for a primary immunodeficiency which revealed a hemizygous pathogenic variant in the magnesium transporter 1 (MAGT1) gene (c.580dup; p.Ser194Phefs*3). This variant is a duplication at nucleotide position 580 that creates a premature stop codon 3 amino acids downstream from this location. The patient subsequently underwent a carbohydrate deficient transferrin test (CDT) for congenital disorders of glycosylation (CDG) that revealed moderately elevated transferrin mono-oligosaccharide to di-oligosaccharide and Apo CIII-1/Apo CIII-2 ratios, consistent with the diagnosis of MAGT1-CDG (XMEN; X-linked immunodeficiency with magnesium defect, EBV infection, and neoplasia). Additionally, NKG2D surface expression was reduced by ~90% on the CD8T cells, and by ~85% on the NK cells in the patient sample compared to the control sample assessed in parallel. The patient continues to test negative for EBV infection by PCR. ConclusionXMEN disease (OMIM number 300853) is a rare, combined immunodeficiency resulting from a mutation in the magnesium transporter 1 gene (MAGT1) located on the X chromosome. Only 36 patients have been reported to have this disease thus far. While the clinical phenotype is variable, the disease is often associated with EBV infection. This case is unique in that the patient was diagnosed due to a history of severe warts, atopy, and hypogammaglobulinemia in the absence of EBV infection.

Inverse effects of APOC2 and ANGPTL4 on the conformational dynamics of lid-anchoring structures in lipoprotein lipase

The lipolytic processing of triglyceride-rich lipoproteins (TRLs) by lipoprotein lipase (LPL) is crucial for the delivery of dietary lipids to the heart, skeletal muscle, and adipose tissue. The processing of TRLs by LPL is regulated in a tissue-specific manner by a complex interplay between activators and inhibitors. Angiopoietin-like protein 4 (ANGPTL4) inhibits LPL by reducing its thermal stability and catalyzing the irreversible unfolding of LPL's α/β-hydrolase domain. We previously mapped the ANGPTL4 binding site on LPL and defined the downstream unfolding events resulting in LPL inactivation. The binding of LPL to glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 protects against LPL unfolding. The binding site on LPL for an activating cofactor, apolipoprotein C2 (APOC2), and the mechanisms by which APOC2 activates LPL have been unclear and controversial. Using hydrogen-deuterium exchange/mass spectrometry, we now show that APOC2's C-terminal α-helix binds to regions of LPL surrounding the catalytic pocket. Remarkably, APOC2's binding site on LPL overlaps with that for ANGPTL4, but their effects on LPL conformation are distinct. In contrast to ANGPTL4, APOC2 increases the thermal stability of LPL and protects it from unfolding. Also, the regions of LPL that anchor the lid are stabilized by APOC2 but destabilized by ANGPTL4, providing a plausible explanation for why APOC2 is an activator of LPL, while ANGPTL4 is an inhibitor. Our studies provide fresh insights into the molecular mechanisms by which APOC2 binds and stabilizes LPL-and properties that we suspect are relevant to the conformational gating of LPL's active site.

Tocilizumab-related hypertriglyceridemia is independent of key molecules regulating lipid metabolism.

Tocilizumab (TCZ) treatment is associated with dyslipidaemia, including a rise in triglycerides through a mechanism poorly understood. Three molecules play key roles in the regulation of triglyceride metabolism: apolipoprotein C-III (ApoC-III), angiopoietin-like protein 4(ANGPLT4) and lipoprotein lipase (LPL). The aim of this work was to analyse whether the changes in triglycerides shown by TCZ-treated RA patients could stem from the dysregulation that can occur in these regulatory molecules. Twenty-seven RA patients included in the TOCRIVAR study who received TCZ (8 mg/kg IV/q4w) were evaluated at baseline and at Weeks 12, 24 and 52 of treatment. ANGPTL4, ApoC-III and LPL, a complete lipid profile and RA disease activity, were analysed at baseline and at each visit. Multivariable linear mixed models were performed to study changes over time in lipids and regulatory molecules. After 24 weeks of TCZ treatment, HDL cholesterol, apolipoprotein A1 and triglycerides increased, whereas lipoprotein (a) decreased significantly from baseline values. However, 1 year after TCZ, no significant differences in lipid pattern were observed with respect to baseline. Serum ANGPTL4 and Apo-CIII levels decreased gradually over time, both being significantly lower than baseline values at Week 52. LPL concentration did not change significantly during TCZ treatment. Remarkably, the elevation of triglycerides at Week 24 maintained its statistical significance after adjusting for the changes in ApoC-III, ANGPTL4 and LPL. In TCZ-treated RA patients basal serum levels of ANGPLT4 and ApoC-III, but not LPL, decreased significantly. However, the elevation of triglycerides after TCZ was not related to changes in these regulatory molecules.

Silencing ApoC3 alleviates LPS-induced acute lung injury by inhibiting TLR signaling pathway.

This study aims to confirm whether apolipoprotein C3 (ApoC3) can regulate the inflammatory response and tissue damage in acute lung injury (ALI) and explore its regulatory pathway. ALI mouse model was established by intraperitoneal injection of lipopolysaccharide (LPS). ApoC3 levels were detected by real-time quantitative polymerase chain reaction, immunohistochemistry, and western blot assays. The levels of various inflammatory factors were detected by enzyme-linked immunosorbent assay and western blot analysis. Finally, the expression of toll-like receptor (TLR)/nuclear factor kappa B (NF-κB) signaling pathway-related protein [TLR2, myeloid differentiation primary response protein 88 (MyD88), IL-1 receptor-associated kinase 1 (IRAK1), NF-κB p65, and inhibitor of kappa B alpha (IκBα)], SLP adaptor and CSK interacting membrane protein (SCIMP), spleen tyrosine kinase (Syk), and phosphorylated (p)-Syk was detected by western blot analysis. ApoC3 was overexpressed in ALI mouse lung tissue and cell inflammation model. Silencing ApoC3 reduced inflammatory factors and alleviated lung tissue damage in ALI mice. Silencing ApoC3 reduced inflammatory factors and downregulated the expression of TLR2, MyD88, IRAK1, NF-κB p65, and increased IκBα expression in LPS-treated RAW264.7 cells. Moreover, co-transfection of si-TLR2 and shApoC3 further enhanced the inhibitory effects on the levels of inflammatory factors induced by silencing ApoC3. ApoC3 overexpression increased the levels of inflammatory factors and protein expression of SCIMP and p-Syk, while silencing TLR2 reversed the promotive effects of ApoC3 overexpression on above factors. In LPS-induced ALI mouse model and inflammatory cell model, downregulation of ApoC3 reduced inflammatory factors and relieved tissue damage. This process might be achieved through the TLR pathway.

Effects of Moderate Exercise Training On ApoE And ApoCIII In Metabolic Syndrome

Introduction: Metabolic syndrome (MetS) is an endocrinopathy with a combination of cardiovascular and metabolic compounds. In our study, it is expected to obtain results showing that mortality rate, loss of workforce, and treatment costs due to disorders caused by MetS can be reduced by physical exercise. The study analyses the effect of moderate exercise training on this Apolipoprotein E (ApoE), Apolipoprotein CIII (ApoCIII), adiponectin, resistin, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) which are thought to have a role in the deterioration of glucose and lipid metabolism in MetS. Methods: This clinical experimental study consists of 3 groups. The MetS+E (n=24) group, which included the participants who agreed to participate in the exercise program in addition to their medical treatment, the MetS (n=23) group who received medical treatment but did not exercise, and the Control+E (n=25) group, which included healthy volunteers who had the same protocol as MetS+E ApoE, ApoCIII, adiponectin, resistin, IL-6, and TNF-α plasma levels of all participants were measured both at the beginning of the study and at the end of the protocol. Results: At the end of the study we reached the following findings; insulin and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) levels decreased in exercise groups (p=0,03). ApoCIII levels increased in all the groups after the study (p&lt;0,01). IL-6 levels decreased in MetS+E (p&lt;0,01) and Control+E (p=0,037). ApoE (p=0,01) and TNF-α (p=0,037) levels decreased only in the Control+E group. Conclusion: Training showed metabolic, anti-inflammatory, and physical improvements independent of ApoE and ApoCIII in those with MetS.

APOC1 predicts a worse prognosis for esophageal squamous cell carcinoma and is associated with tumor immune infiltration during tumorigenesis.

Background: Esophageal carcinoma (ESCA), a common malignant tumor of the digestive tract with insidious onset, is a serious threat to human health. Despite multiple treatment modalities for patients with ESCA, the overall prognosis remains poor. Apolipoprotein C1 (APOC1) is involved in tumorigenesis as an inflammation-related molecule, and its role in esophageal cancer is still unknown. Methods: We downloaded documents and clinical data using The Cancer Genome Atlas (TCGA)and Gene Expression Omnibus (GEO) databases. We also conducted bioinformatics studies on the diagnostic value, prognostic value, and correlation between APOC1 and immune infiltrating cells in ESCA through STRING (https://cn.string-db.org/), the TISIDB (http://cis.hku.hk/TISIDB/) website, and various other analysis tools. Results: In patients with ESCA, APOC1 was significantly more highly expressed in tumor tissues than in normal tissues (p < 0.001). APOC1 could diagnose ESCA more accurately and determine the TNM stage and disease classification with high accuracy (area under the curve, AUC≥0.807). The results of the Kaplan-Meier curve analysis showed that APOC1 has prognostic value for esophageal squamous carcinoma (ESCC) (p = 0.043). Univariate analysis showed that high APOC1 expression in ESCC was significantly associated with worse overall survival (OS) (p = 0.043), and multivariate analysis shows that high APOC1 expression was an independent risk factor for the OS of patients with ESCC (p = 0.030). In addition, the GO (gene ontology)/KEGG (Kyoto encyclopedia of genes and genomes) analysis showed a concentration of gene enrichment in the regulation of T-cell activation, cornification, cytolysis, external side of the plasma membrane, MHC protein complex, MHC class II protein complex, serine-type peptidase activity, serine-type endopeptidase activity, Staphylococcus aureus infection, antigen processing and presentation, and graft-versus-host disease (all p < 0.001). GSEA (gene set enrichment analysis) showed that enrichment pathways such as immunoregulatory-interactions between a lymphoid and non-lymphoid cell (NES = 1.493, p. adj = 0.023, FDR = 0.017) and FCERI-mediated NF-KB activation (NES = 1.437, p. adj = 0.023, FDR = 0.017) were significantly enriched in APOC1-related phenotypes. In addition, APOC1 was significantly associated with tumor immune infiltrating cells and immune chemokines. Conclusion: APOC1 can be used as a prognostic biomarker for esophageal cancer. Furthermore, as a novel prognostic marker for patients with ESCC, it may have potential value for further investigation regarding the diagnosis and treatment of this group of patients.

Dietary Monounsaturated and Polyunsaturated Fatty Acids are Comparable in their Effects on Hepatic Apolipoprotein mRNA Abundance and Liver Lipid Concentrations when Substituted for Saturated Fatty Acids in Cynomolgus Monkeys

Although studies have shown that saturated and polyunsaturated fats can mediate plasma lipid and apolipoprotein (apo) concentrations at the mRNA level, there is little data on the role of monounsaturated fats. We determined hepatic lipid and apo mRNA levels in 10 cynomolgus monkeys fed three diets that provided 30% of energy as fat with 0.1% cholesterol by weight and differed solely by the substitution of saturated, mono- and polyunsaturated fats as 60% of total fat energy. Total, LDL, and HDL cholesterol, as well as LDL apo B, HDL apo A-I and HDL total apo C concentrations, were reduced with the mono- and polyunsaturated fat diets relative to the saturated fat diet. Although fat saturation did not significantly affect hepatic apo A-I, B, C-II, or E mRNA abundance, hepatic apo C-III mRNA concentrations were uniformly lower (-23%, P < 0.01) with the mono- and polyunsaturated fat diets than with the saturated fat diet. Interestingly, liver triglycerides were significantly elevated with the monounsaturated fat diet relative to the saturated fat diet, but no other differences in hepatic lipids were noted among diets. Hepatic triglyceride composition was shown to reflect dietary fatty acid composition, with liver triglycerides enriched in myristic and palmitic fatty acids during the saturated fat diet, oleic acid during the monounsaturated fat diet and linoleic acid during the polyunsaturated fat diet. We conclude that dietary monounsaturated fats are comparable to polyunsaturated fats in their effects on hepatic lipid and apo mRNA levels in this species, with both unsaturated fats significantly reducing only hepatic apo C-III mRNA abundance relative to saturated fat.

Leveraging Genetics to Address the Role of GALNT2 on Atherogenic Dyslipidemia.

Several studies have shown that downregulation of GALNT2(PolypeptideN-Acetylgalactosaminyltransferase2), encoding polypeptide N-acetylgalactosaminyltransferase 2, decreases high-density lipoprotein cholesterol (HDL-C) and increases triglycerides levels by glycosylating key enzymes of lipid metabolism, such as angiopoietin like 3, apolipoprotein C-III, and phospholipid transfer protein. GALNT2 is also a positive modulator of insulin signaling and action, associatedwith in vivo insulin sensitivity and during adipogenesis strongly upregulates adiponectin. Thus, the hypothesis that GALNT2 affects HDL-C and triglycerides levels also through insulin sensitivity and/or circulating adiponectin, is tested. In 881 normoglycemic individuals the G allele of rs4846914 SNP at theGALNT2 locus, known to associate with GALNT2 downregulation, is associated with low HDL-C and high values of triglycerides, triglycerides/HDL-C ratio, and theHomeostaticModelAssessmentofinsulin resistance HOMAIR (p-values = 0.01, 0.027, 0.002, and 0.016, respectively). Conversely, no association is observed with serum adiponectin levels (p= 0.091). Importantly, HOMAIR significantly mediates a proportion of the genetic association with HDL-C (21%, 95% CI: 7-35%, p= 0.004) and triglyceride levels (32%, 95% CI: 4-59%, p= 0.023). The results are compatible with the hypothesis that, besides the effect on key lipid metabolism enzymes, GALNT2 alters HDL-C and triglyceride levels also indirectly through a positive effect on insulin sensitivity.

Nutrigenetic Interaction Between Apolipoprotein C3 Polymorphism and Fat Intake in People with Nonalcoholic Fatty Liver Disease

BackgroundRecent genome-wide association studies have revealed that nonalcoholic fatty liver disease (NAFLD) is correlated with genetic polymorphisms. However, the effects of genetic variation on nutritional metabolism and NAFLD are complex and further studies are still needed. ObjectivesThis study aimed to assess the nutritional characteristics interacting with the correlation between genetic predisposition and NAFLD. MethodsWe assessed the 2013–2017 health examination data of 1191 adults aged ≥40 y living in Shika town, Ishikawa Prefecture, Japan. Adults with moderate or heavy alcohol consumption and hepatitis were excluded, and 464 participants who underwent genetic analyses were included in the study. Abdominal echography was performed to diagnose fatty liver condition, and dietary intake and nutritional balance were evaluated using the brief self-administered diet history questionnaire. NAFLD-related gene polymorphisms were identified using Japonica Array v2 (Toshiba). ResultsAmong the 31 single nucleotide polymorphisms, only the polymorphism T-455C in the apolipoprotein C3 (APOC3) gene (rs2854116) was significantly associated with fatty liver condition. The condition was more common in participants with heterozygotes of the APOC3 gene (rs2854116) than in those with the TT and CC genotypes. Significant interactions were observed between NAFLD and the intake of fat, vegetable fat, MUFAs, PUFAs, cholesterol, n-3 FAs, and n-6 FAs. Moreover, participants with NAFLD who presented with the TT genotype had a significantly higher fat intake than those without NAFLD. ConclusionsThe polymorphism T-455C in the APOC3 gene (rs2854116) and fat intake are associated with the NAFLD risk in Japanese adults. Participants with a fatty liver who presented with the TT genotype of rs2854116 had a higher fat intake. Such nutrigenetic interaction can deepen our understanding of the NAFLD pathology. Moreover, in clinical settings, the correlation between genetic factors and nutrition intake should be considered in personalized nutritional interventions against NAFLD. Curr Dev Nutr 2023;xx:xx.The study was registered in the University Hospital Medical Information Network Clinical Trials Registry as UMIN 000024915.