Reduced Plasma Low-density Lipoprotein Cholesterol Research Articles

Differences among Lactiplantibacillus plantarum strains isolated from different fermented foods in their potential cholesterol-lowering properties

Elevated levels of plasma low-density lipoprotein (LDL) cholesterol have been associated with incident atherosclerotic cardiovascular disease. Animal studies and clinical trials have demonstrated that several Lactiplantibacillus plantarum strains are effective in reducing plasma LDL cholesterol levels. However, it is unclear whether the habitats from which Lactiplantibacillus plantarum strains are isolated have an impact on their potential cholesterol-lowering properties. In this study, 107 Lactiplantibacillus plantarum strains isolated from three habitats (20 isolated from fermented dairy products, 23 from fermented grape must, and 64 from fermented vegetables) were compared for their potential cholesterol-lowering properties on an origin scale. These properties included acid resistance, bile tolerance, surface hydrophobicity, and bile acid deconjugation. The results showed that the fermented dairy products-derived strains were the most bile-tolerant and hydrophobic, the fermented grape must-derived strains were the most effective at hydrolyzing conjugated bile acids, and the fermented vegetables-derived strains were the most acid-resistant. Bile salt hydrolase (BSH) genes were detected in 97.2% of the total strains and 100% of the fermented dairy products-derived strains by standard PCR with agarose gel electrophoresis detection. In the 104 bsh genes-containing strains, 92.3% had detectable BSH activity (n = 96). These BSH-positive strains exhibited a greater substrate preference for glycine-conjugated bile acids than taurine-conjugated bile acids. Overall, the fermented dairy products-derived strains appeared to have greater cholesterol-lowering potential than those isolated from the other two habitats. This study provided valuable information regarding where to obtain Lactiplantibacillus plantarum strains with greater cholesterol-lowering potential.

PCSK9 regulates myofibroblast transformation through the JAK2/STAT3 pathway to regulate fibrosis after myocardial infarction

Cardiac fibrosis is pivotal in the progression of numerous cardiovascular diseases. This phenomenon is hallmarked by an excessive deposition of ECM protein secreted by myofibroblasts, leading to increased myocardial stiffness. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that belongs to the proprotein-converting enzyme family. It has emerged as a viable therapeutic target for reducing plasma low-density lipoprotein cholesterol. However, the exact mechanism via which PCSK9 impacts cardiac fibrosis remains unclear. In the present research, an increase in circulating PCSK9 protein levels was observed in individuals with myocardial infarction and rat models of myocardial infarction. Moreover, the inhibition of circulating PCSK9 in rats was found to reduce post-infarction fibrosis. In vitro experiments further demonstrated that overexpression of PCSK9 or stimulation by extracellular PCSK9 recombinant protein enhanced the transformation of cardiac fibroblasts to myofibroblasts. This process also elevated collagen Ⅰ, and Ⅲ, as well as α-SMA protein levels. However, these effects were countered when co-incubated with the STAT3 inhibitor S3I-201. This study suggests that PCSK9 may function as a novel regulator of myocardial fibrosis, primarily via the JAK2/STAT3 pathway.

Targeted Degradation of PCSK9 In Vivo by Autophagy-Tethering Compounds.

Proprotein convertase subtilisin/kexin type-9 (PCSK9), a secreted protein that is synthesized and spontaneously cleaved in the endoplasmic reticulum, has become a hot lipid-lowering target chased by pharmaceutical companies in recent years. Autophagosome-tethering compounds (ATTECs) represent a new strategy to degrade targeted biomolecules. Here, we designed and synthesized PCSK9·ATTECs that are capable of lowering PCSK9 levels via autophagy in vivo, providing the first report of the degradation of a secreted protein by ATTECs. OY3, one of the PCSK9·ATTECs synthesized, shows greater potency to reduce plasma low-density lipoprotein cholesterol (LDL-C) levels and improve atherosclerosis symptoms than treatment with the same dose of simvastatin. OY3 also significantly reduces the high expression of PCSK9 caused by simvastatin administration in atherosclerosis model mice and subsequently increases the level of low-density lipoprotein receptor, promoting simvastatin to clear plasma LDL-C and alleviate atherosclerosis symptoms. Thus, we developed a new candidate compound to treat atherosclerosis that could also promote statin therapy.

Impact of providing genetics-based future cardiovascular risk on LDL-C in patients with familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant monogenic disease characterized by high low-density lipoprotein cholesterol (LDL-C) levels. Although carrying causative FH variants is associated with coronary heart disease (CHD), it remains unclear whether disclosing its associated cardiovascular risk affects outcomes in patients with FH. We aimed to evaluate the efficacy of providing future cardiovascular risk based on genetic testing in addition to a standard FH education program. We conducted a randomized, wait-list controlled, open-label, single-center trial. In the intervention group, we reported a future cardiovascular risk based on the genetic testing adding to standard FH education at week 0. In the wait-list control group, we only disseminated standard FH education according to the guidelines at week 0; they later received a genetic testing-based cardiovascular risk assessment at week 24. The primary endpoint of this study was the plasma LDL-C level at week 24. Fifty eligible patients with clinically diagnosed FH, without a history of CHD, were allocated to the intervention group (n=24) or the wait-list control group (n=26). At week 24, the intervention group had a significantly greater reduction in LDL-C levels than the wait-list control group (mean changes, -13.1mg/dL vs. 6.6mg/dL; difference, -19.7mg/dL; 95% confidence interval, -34 to -5.6; p=0.009). This interventional effect was consistent with FH causative variant carriers but not with non-carriers. In addition to standard FH care, providing future cardiovascular risk based on genetic testing can further reduce plasma LDL-C levels, particularly among FH causal variant carriers. Japan Registry of Clinical Trials (jRCTs04218002). URL: https://jrct.niph.go.jp/latest-detail/jRCTs042180027.

Advanced progress of the relationship between PCSK9 monoclonal antibodies and hyperglycemic adverse events.

Long-term use of statins had been confirmed to cause an increase in hyperglycemic adverse events (HAEs), whose mechanism has been well understood. Proprotein convertase subtilisin/kexin type 9 (PCSK9) monoclonal antibodies (PCSK9-mAbs), a kind of new lipid-lowering drug, can effectively reduce plasma low-density lipoprotein cholesterol levels in patients with CHD and have been widely used. However, animal experiments, Mendelian randomization studies, clinical researches and Meta-analyses which focused on the relationship between PCSK9-mAbs and HAEs had reached different conclusions, which has attracted great attention from clinicians. The newest FOURIER-OLE randomized controlled trial followed PCSK9-mAbs users for over 8 years, whose results suggested that long-term use of PCSK9-mAbs did not increase the incidence of HAEs. Newest Meta-analyses also indicated that there was no relationship between PCSK9-mAbs and NOD. Meanwhile, genetic polymorphisms and variants related to PCSK9 might have effects on HAEs. According to the results of current studies, there is no significant relationship between PCSK9-mAbs and HAEs. However, longer-term follow-up studies are still needed to confirm it. Although PCSK9 genetic polymorphisms and variants may affect the possible occurrence of HAEs, there is no need to perform relevant genetic testing before applying PCSK9-mAbs.

PCSK9 Inhibitors as Adjunctive Therapies in Hypercholesterolemia: Benefits, Limitations, and Possible Alternatives

AbstractThe clinical application of statins as anti‐hypercholesterolemia medications, while very beneficial, remains limited by intolerance and side effects. Statins increase the production of proprotein convertase subtilisin/kexin type 9 (PCSK9), which degrades low‐density lipoprotein (LDL) receptor and limits circulating LDL cholesterol (LDLC) uptake. PCSK9 also promotes cardiomyocyte and vascular smooth muscle cell apoptosis and vascular injury. Several PCSK9 inhibitors (evolocumab, alirocumab, and inclisiran) are highly effective at reducing plasma LDLC levels and moderately effective at protecting against cardiovascular disease. However, their long‐term use needs to take the following issues into account: i) PCSK9 deficiency leads to various pathologies like heart failure and liver steatosis, ii) PCSK9 regulates lipid homeostasis, iii) depletion of circulating PCSK9 may itself upregulate PCSK9 expression, and iv) the cost of available inhibitors is beyond the reach of most people. Therefore, the long‐term safety and affordability of PCSK9 inhibitors needs to be revisited and additional therapeutic options need to be explored.

New Loss-of-Function Mutations in PCSK9 Reduce Plasma LDL Cholesterol.

Lower plasma levels of LDL (low-density lipoprotein) cholesterol (LDL-C) can reduce the risk of atherosclerotic cardiovascular disease. The loss-of-function mutations in PCSK9 (proprotein convertase subtilisin/kexin type 9) have been known to associate with low LDL-C in many human populations. PCSK9 genetic variants in Chinese Uyghurs who are at high risk of atherosclerotic cardiovascular disease due to their dietary habits have not been reported. The study involved the whole-exome and target sequencing of college students from Uyghur and other ethnic groups in Xinjiang, China, for the association of PCSK9 loss-of-function mutations with low plasma levels of LDL-C. The mechanisms by which the identified mutations affect the function of PCSK9 were investigated in cultured cells using biochemical and cell assays. The causal effects of the identified PCSK9 mutations on LDL-C levels were verified in mice injected with adeno-associated virus expressing different forms of PCSK9 and fed a high-cholesterol diet. We identified 2 PCSK9 mutations-E144K and C378W-in Chinese Uyghurs with low plasma levels of LDL-C. The E144K and C378W mutations impaired the maturation and secretion of the PCSK9 protein, respectively. Adeno-associated virus-mediated expression of E144K and C378W mutants in Pcsk9 KO (knockout) mice fed a high-cholesterol diet also hampered PCSK9 secretion into the serum, resulting in elevated levels of LDL receptor in the liver and reduced levels of LDL-C in the serum. Our study shows that E144K and C378W are PCSK9 loss-of-function mutations causing low LDL-C levels in mice and probably in humans as well.

Real-World Data on Comparison of Lipid-Lowering Effects between Alirocumab and Evolocumab in Patients with Hypercholesterolemia.

Even though the proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, alirocumab and evolocumab, have been approved to reduce plasma low-density lipoprotein cholesterol (LDL-C) and the risk of atherosclerotic cardiovascular disease in high-risk patients, real-world data showing comparisons of the lipid-lowering effects between alirocumab and evolocumab are scarce because of the low prescription rates of PCSK9 inhibitors in clinical practice. Between Feb 2018 and Sep 2021, 22 patients who received alirocumab and 22 patients who received evolocumab at a tertiary medical center were enrolled. The patients' baseline characteristics, prescribed medications, plasma LDL-C levels, and percentages of reduction in LDL-C were compared between alirocumab users and evolocumab users. The alirocumab users more frequently received ezetimibe treatment (72.7% vs. 40.9%, p = 0.03) and had higher baseline LDL-C (165.6 ± 63.2 mg/dL vs. 130.8 ± 56.3 mg/dL, p = 0.04) compared with the evolocumab users. At 6 months of follow-up, the plasma LDL-C levels in the alirocumab users were similar to those in the evolocumab users (79.3 ± 64.0 mg/dL vs. 63.5 ± 44.1 mg/dL, p = 0.48). Additionally, the percentages of LDL-C reduction following treatment were similar between the alirocumab users and evolocumab users (-47.0% ± 45.0% vs. -49.8 ± 24.9%, p = 0.66). The LDL-C lowering effects of alirocumab are similar to those of evolocumab in clinical practice.

New, Novel Lipid-Lowering Agents for Reducing Cardiovascular Risk: Beyond Statins.

Statins are the cornerstone of the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD). However, even under optimal statin therapy, a significant residual ASCVD risk remains. Therefore, there has been an unmet clinical need for novel lipid-lowering agents that can target low-density lipoprotein cholesterol (LDL-C) and other atherogenic particles. During the past decade, several drugs have been developed for the treatment of dyslipidemia. Inclisiran, a small interfering RNA that targets proprotein convertase subtilisin/kexin type 9 (PCSK9), shows comparable effects to that of PCSK9 monoclonal antibodies. Bempedoic acid, an ATP citrate lyase inhibitor, is a valuable treatment option for the patients with statin intolerance. Pemafibrate, the first selective peroxisome proliferator-activated receptor alpha modulator, showed a favorable benefit-risk balance in phase 2 trial, but the large clinical phase 3 trial (PROMINENT) was recently stopped for futility based on a late interim analysis. High dose icosapent ethyl, a modified eicosapentaenoic acid preparation, shows cardiovascular benefits. Evinacumab, an angiopoietin-like 3 (ANGPTL3) monoclonal antibody, reduces plasma LDL-C levels in patients with refractory hypercholesterolemia. Novel antisense oligonucleotides targeting apolipoprotein C3 (apoC3), ANGPTL3, and lipoprotein(a) have significantly attenuated the levels of their target molecules with beneficial effects on associated dyslipidemias. Apolipoprotein A1 (apoA1) is considered as a potential treatment to exploit the athero-protective effects of high-density lipoprotein cholesterol (HDL-C), but solid clinical evidence is necessary. In this review, we discuss the mode of action and clinical outcomes of these novel lipid-lowering agents beyond statins.

Evaluation of the distribution and excretion of [14C]-inclisiran following single subcutaneous administration in cynomolgus monkeys

Inclisiran is a small interfering RNA molecule that was designed to reduce plasma low-density lipoprotein cholesterol (LDL-C) levels by inhibiting proprotein convertase subtilisin/kexin type 9 synthesis in the liver. This study aimed to characterize the tissue distribution and excretion of inclisiran after dosing in monkeys.A single 20 mg/kg subcutaneous injection of [14C]-inclisiran was administered to 12 male cynomolgus monkeys. Plasma concentrations and tissue binding parameters for inclisiran were assessed up to 42 days after injection using liquid scintillation of blood samples and tissue homogenates, as well as quantitative whole-body autoradiography.Radioactivity was highest in the liver at all time points from 24 h onward and remained elevated throughout the entire study period. Radioactivity was also detected in the kidneys and bladder wall, returning to low levels by 24 h. The concentration of radioactivity in the liver (402.97 μg equivalent/g) was 15.7-fold higher than in the kidneys (25.70 μg equivalent/g). Very low amounts of radioactivity were detected in all other tissues examined. The highest radioactivity in tissue homogenates was in the liver and kidney pyramid (327 and 351 μg equivalent/g, respectively).This study confirmed the selective uptake of inclisiran by the liver, indicating that the N-acetylgalactosamine linker allows for selective uptake via the asialoglycoprotein receptors expressed on hepatocytes compared with other tissues that lack asialoglycoprotein receptors. The long tissue retention in the liver supports the infrequent, biannual dosing schedule for inclisiran in the clinic and the temporal disconnect between short-term systemic exposure and sustained lowering of LDL-C.

Acanthaster planci Inhibits PCSK9 Gene Expression via Peroxisome Proliferator Response Element (PPRE) and Activation of MEK and PKC Signaling Pathways in Human Liver Cells.

A constantly elevated level of low-density lipoprotein cholesterol (LDL-C) is mainly associated with the development of atherosclerosis. The use of statins as a treatment for reducing plasma LDL-C levels has led, in some cases, to adverse side effects, including a decrease in hepatic LDL receptor (LDLR), the receptor responsible for the uptake of circulating LDL-C. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is an enzyme responsible for directing the LDLR–LDL-C complex to lysosomal degradation upon transport into cells, preventing the recycling of LDLR to the cell surface. Therefore, PCSK9 may offer a new target for reducing the levels of plasma LDL-C. In this study, we investigated the mechanisms of action of a selected fraction of A. planci on PCSK9 gene expression, as well as the effect of the fraction on the level of LDLR protein and the uptake of LDL-C. Using real-time PCR, it was shown that the selected A. planci fraction reduced the gene expression of PCSK9 in human liver HepG2 cells. Immunocytochemistry analysis demonstrated that the selected A. planci fraction increased the LDLR protein level and LDL-C uptake in HepG2 cells. Promoter mutational and gene expression analyses revealed that PPRE, a binding site for peroxisome proliferator–activated receptor (PPAR), was responsible for mediating the inhibitory effect of the selected fraction on PCSK9 mRNA. In addition, MAP kinase and PKC components of the signal transduction pathway were activated, inducing the action of the selected A. planci fraction in decreasing PCSK9 gene expression. These findings suggest that the selected fraction shows good potential for reducing circulating LDL-C and, thus, may be a good therapeutic intervention to prevent the progression of atherosclerosis.

Evidence of Direct Hepatic Secretion of Low density Lipoprotein (LDL) in Mice

<h3>Lead Author's Financial Disclosures</h3> Nothing to disclose. <h3>Study Funding</h3> National Lipid Association Junior Faculty Research Award 2020, NIH P01HL151328 and HL45095 (IJG). <h3>Background/Synopsis</h3> LDL is the major atherogenic lipoprotein causing atherosclerosis, leading to cardiovascular disease (CVD), the primary cause of morbidity and mortality in the United States. Lipoprotein lipase (LpL) is the rate limiting enzyme hydrolyzing triglyceride rich lipoproteins in the circulation. Current understanding is that LpL mediated hydrolysis of very low density lipoprotein (VLDL) generates cholesterol rich LDL particles in the circulation. However, evidence from in vitro studies as well as some human kinetic data suggest that the liver might directly secrete LDL into the circulation. <h3>Objective/Purpose</h3> In this study, we determine whether combined deficiency of lipoprotein lipase and hepatic LDL receptor (LDLR) would lead to decreased circulating LDL cholesterol (LDL-C) levels. <h3>Methods</h3> We used a mouse model of tamoxifen inducible global LpL deficiency (iLpl-/-). To knock down hepatic genes like LDLR and hepatic lipase (HL) we utilized anti sense oligonucleotides (ASOs). <h3>Results</h3> As expected, iLpl-/- mice display reduced plasma LDL-C levels compared to control mice (5 mg/dl vs 30 mg/dl). To determine whether LDL-C would increase with knock down of hepatic LDLRs, we used LDLR ASO in control and iLpl-/- mice. As anticipated, LDL-C levels increased in control mice to 150 mg/dl. Remarkably, plasma LDL-C also increased in iLpl-/- mice to levels similar to that of control mice. We then fed the mice a high cholesterol western diet for two weeks; this increased LDL-C levels equally in both mice to 300 mg/dl. When we overexpressed PCSK9 to inhibit LDLR in iLpl-/- mice, we again observed increases in LDL-C similar to control mice with PCSK9 overexpression. Further, to test if HL, another extracellular triglyceride lipase, is converting VLDL to LDL in iLpl-/- mice, we knocked down HL in control and iLpl-/- mice. HL knockdown did not alter LDL-C levels in control or iLpl-/- mice. <h3>Conclusions</h3> These data suggest the presence of direct LDL secretion from liver. We are investigating why this is apparent only with concomitant loss of LpL and LDLRs. We postulate that LDLRs have an additional gate-keeping function to halt secretion of newly synthesized LDL particles from the liver in addition to their well-established role in clearance of plasma LDL. When LDLRs are limiting or in patients with combined hyperlipidemia, direct LDL production may constitute a major source of circulating LDL. If so, this could uncover a novel approach to treat familial hypercholesterolemia.

Gene-diet interaction in plasma lipid response to plant sterols and stanols: A review of clinical trials

• PS reduce plasma LDL-C levels by 6–12%. • LDL-C response to PS intake modulated by variants in cholesterol metabolism genes. • Only CYP7A1 c. −204C > A variant offered an hypocholesterolemic effect. • Standardization of clinical trials evaluating gene-diet interaction is necessary. Plant sterols and stanols (PS) are well known for their cholesterol-lowering effect by reducing intestinal absorption of cholesterol. However, genetic factors modulate the low-density lipoprotein cholesterol (LDL-C) response to PS therapy. This review examines clinical trials evaluating the impact of the main genes associated with response of plasma lipid concentrations to PS intake: APOE, CYP7A1, ABCG5/G8, NPC1L1, CETP, APOA4/A5, SCARBI, HMGCR, PPARα, LIPC, MTHFR and LPA. Evidence indicates that carriers of mutant allele of the CYP7A1 c. −204 A > C variant experience a greater plasma cholesterol reduction after PS intake, although there is discrepancy for the rest of genetic variants studied. Thus, it is necessary to standardize the design of these studies to validate the use of genetic information as a predictor marker of the response to the intervention with PS, to scientifically validate the use of these data in the personalized dietary advice.

Telemedicine assists in the management of proatherogenic dyslipidemia and postprandial glucose variability in patients with type 2 diabetes mellitus: a cross-sectional study.

ObjectiveCoronary heart disease (CHD) is a prevalent complication of type 2 diabetes mellitus (T2DM). The proatherogenic low-density lipoprotein (LDL) cholesterol is an established risk factor of cardiovascular disease, and evidence also suggests that postprandial plasma glucose (PPG) levels closely delineate CHD mortality in diabetes. The investigators hypothesized that the addition of telehealth consultation to standard antidiabetic therapy may help to reduce postprandial glucose variability and plasma LDL cholesterol levels in patients with T2DM.MethodsThis cross-sectional study enrolled patients with newly diagnosed T2DM who received standard antidiabetic therapy with or without additional telehealth consultation. Participants received blood tests for plasma lipid profile and glucose levels at the diagnosis of diabetes and after 1 month of therapeutic intervention. Laboratory results were compared between treatment groups to determine the efficacy of complementary telehealth consultation.ResultsIn this study, 375 participants were enrolled. The standard treatment group had considerably greater levels of plasma LDL cholesterol than recipients of telehealth consultation (110 mg/dL vs 93.1 mg/dL, P < 0.001). Moreover, patients receiving standard treatment had greater levels of fasting plasma glucose (104 mg/dL vs 98.5 mg/dL, P = 0.027), 2-h PPG (169 mg/dL vs 111 mg/dL, P < 0.001), and postprandial glucose variability (65.4 mg/dL vs 12.8 mg/dL, P < 0.001) than participants under telehealth consultation.ConclusionsTelemedicine in addition to standard antidiabetic therapy helped to reduce plasma LDL cholesterol levels and postprandial glucose variability in patients with newly diagnosed T2DM. Therefore, telehealth consultation is a suitable complement to pharmacologic therapy for diabetic patients to assist in the management of proatherogenic dyslipidemia and postprandial glucose variability.

Intranasal Oxytocin Improves Lean Muscle Mass and Lowers LDL Cholesterol in Older Adults with Sarcopenic Obesity: A Pilot Randomized Controlled Trial

ObjectivesObesity is associated with sarcopenia in older adults, and weight loss can lead to further muscle mass loss. Oxytocin decreases with age, and animal studies suggest that oxytocin administration has trophic effects on skeletal muscle cells and reduces adiposity. We conducted a clinical trial to examine the safety and preliminary efficacy of intranasal oxytocin for older adults with sarcopenic obesity. DesignA double-blind, placebo-controlled randomized controlled trial of intranasal oxytocin (24 IU 4 times per day) for 8 weeks. Setting and ParticipantsTwenty-one older (67.5 ± 5.4 years), obese (30–43 kg/m2), sedentary (<2 strenuous exercise per week) adults with slow gait speed (<1 m/s, proxy measure of sarcopenia) were recruited. MeasuresGeneralized estimating equations were used to evaluate the effect of oxytocin on safety/tolerability of oxytocin administration and whole body muscle and fat mass. ResultsAt baseline, body mass index (BMI) was 36.8 ± 3.6 kg/m2, fat mass 46.09 ± 6.99 kg, lean mass 50.98 ± 11.77 kg, fasting plasma glucose (FPG) 92.0 ± 8.9 mg/dL, hemoglobin A1c (HbA1c) 5.7% ± 0.4%, low density lipoprotein (LDL) 111.3 ± 41.5 mg/dL, high-density lipoprotein (HDL) 47.85 ± 10.96 mg/dL, and triglycerides 140.55 ± 83.50 mg/dL. Oxytocin administration was well tolerated without any significant adverse events. Oxytocin led to a significant increase of 2.25 kg in whole body lean mass compared with placebo (P < .01) with a trend toward decreasing fat mass, and a significantly reduced plasma LDL cholesterol by −19.3 mg/dL (P = .023) compared against placebo. There were no significant changes in BMI, appetite scores, glycemia, plasma HDL, triglycerides, or depressive symptoms. Conclusions and ImplicationsThis proof-of-concept study indicates that oxytocin may be useful for the treatment of sarcopenic obesity in older adults. Oxytocin administration may also provide additional cardiovascular benefits.

Surf4 Knockdown Protects Against Cardiovascular Disease

Plasma low-density lipoprotein cholesterol (LDL-C) levels are positively correlated with risk of cardiovascular disease. LDL is produced from catabolism of very low-density lipoprotein (VLDL) that is exclusively secreted from hepatocytes. Inhibition of VLDL secretion reduces plasma LDL-C levels. LDL is cleared from circulation via hepatic LDL receptor (LDLR). Proprotein convertase subtilisin/kexin type 9 (PCSK9) is mainly secreted from the liver and promotes LDLR degradation, increasing plasma LDL-C levels. Understanding mechanisms of VLDL and PCSK9 secretion are crucial for identifying novel therapeutic targets. Surfeit 4 (Surf4) is a cargo receptor that resides in the endoplasmic reticulum (ER). Here, we investigated its role in VLDL and PCSK9 secretion. We generated Surf4 liver specific knockout (Surf4LKO) mice and found that knockout of Surf4 did not affect PCSK9 secretion but significantly reduced plasma levels of cholesterol, triglyceride, and apolipoprotein B (apoB). In cultured human hepatocytes, Surf4 co-immunoprecipitated and co-localized with apoB100, and Surf4 silencing reduced secretion of apoB100. VLDL secretion was impaired in Surf4LKO mice, causing the retention of small lipid particles in the hepatic ER lumen. However, liver lipid levels and plasma alanine aminotransferase activity were comparable in Surf4LKO and Surf4FLOXmice. Furthermore, knockdown of Surf4 in LDLR knockout (Ldlr-/-) mice significantly reduced triglyceride secretion and plasma levels of apoB and non-HDL cholesterol but had no effect on plasma HDL cholesterol or apoA-I levels. Surf4 silencing markedly reduced the development of atherosclerosis without causing notable liver damage. Expression of stearoyl-CoA-1 (SCD1) was reduced in the liver of Surf4LKO mice and Surf4 knockdown Ldlr-/- mice. In summary, Surf4 is not required for PCSK9 secretion, instead it interacts with apoB100 and facilitates VLDL secretion. Hepatic deficiency of Surf4 reduces VLDL secretion and the development of atherosclerosis but does not cause hepatic lipid accumulation or liver damage. Thus, hepatic Surf4 can be a novel therapeutic target to reduce LDL production and the risk of cardiovascular disease. Translational perspective. Patients with homozygous familial hypercholesterolemia harboring LDLR null mutations or with autosomal recessive hypercholesterolemia cannot be effectively treated by currently lipid-lowering drugs, statins and PCSK9 inhibitors. Inhibition of VLDL secretion can markedly reduce plasma levels of cholesterol and the development of atherosclerosis. Our findings that Surf4 facilitated VLDL secretion, and inhibition of Surf4 drastically reduced plasma cholesterol levels and the development of atherosclerosis without causing notable liver damage provide critical information for the development of novel LDL production-based therapies through inhibiting hepatic Surf4.

PCSK9 in Myocardial Infarction and Cardioprotection: Importance of Lipid Metabolism and Inflammation.

Extensive evidence from epidemiologic, genetic, and clinical intervention studies has indisputably shown that elevated low-density lipoprotein cholesterol (LDL-C) concentrations play a central role in the pathophysiology of atherosclerotic cardiovascular disease. Apart from LDL-C, also triglycerides independently modulate cardiovascular risk. Reduction of proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a therapeutic target for reducing plasma LDL-C, but it is also associated with a reduction in triglyceride levels potentially through modulation of the expression of free fatty acid transporters. Preclinical data indicate that PCSK9 is up-regulated in the ischaemic heart and decreasing PCSK9 expression impacts on infarct size, post infarct inflammation and remodeling as well as cardiac dysfunction following ischaemia/reperfusion. Clinical data support that notion in that PCSK9 inhibition is associated with reductions in the incidence of myocardial infarction, stroke, and coronary revascularization and an improvement of endothelial function in subjects with increased cardiovascular risk. The aim of the current review is to summarize the current knowledge on the importance of free fatty acid metabolism on myocardial ischaemia/reperfusion injury and to provide an update on recent evidence on the role of hyperlipidemia and PCSK9 in myocardial infarction and cardioprotection.

Piceatannol reduces resistance to statins in hypercholesterolemia by reducing PCSK9 expression through p300 acetyltransferase inhibition

The purpose of this study was to investigate the role of piceatannol (PT) in statin (rosuvastatin and simvastatin) resistance and tolerance and its association with PCSK9 expression via its p300 inhibitory (p300i) activity. An in vitro study was performed using HepG2 cells that were exposed to statins (rosuvastatin or simvastatin) with or without PT in delipidated serum (DLPS) medium. In the statin exposed conditions, PCSK9 expression was reduced following PT treatment when compared to HepG2 cells w/o PT treatment. Furthermore, no significant difference was observed in the expression of the transcription factors SREBP2 and HNF1α, which regulate PCSK9 expression. This resulted in low density lipoprotein receptor (LDLR) stabilization and reduced cellular cholesterol levels. This indicates that PT epigenetically controls statin-induced PCSK9 expression. Interestingly, PT attenuated p300 histone acetyltransferase (HAT) activity. Moreover, simulation of PT-p300 binding suggested that PT inhibits p300 as PT could be docked in the p300 HAT domain. Furthermore, inhibition of p300 HAT activity using C-646, a selective p300 inhibitor, or through an siRNA system effectively reduced PCSK9 induction upon statin exposure in HepG2 cells. The chromatin immunoprecipitation (ChIP) assays revealed that PT blocked the recruitment of p300 to the PCSK9 promoter region. In summary, PT attenuated statin-induced PCSK9 expression by inhibiting p300 HAT activity. Finally, co-administration of simvastatin and PT for 10 weeks further reduced plasma low-density lipoprotein-cholesterol (LDL-C) levels and stabilized the hepatic LDLR protein level compared with those resulting from single treatment of simvastatin in a high-fat diet-induced hypercholesterolemia mouse model. Our findings indicate that PT is a new nutraceutical candidate to reduce the statin resistance and tolerance that occurs in patients with hypercholesterolemia.

Oral administration of trehangelin-A alleviates metabolic disorders caused by a high-fat diet through improvement of lipid metabolism and restored beneficial microbiota

The present study investigated whether or not the oral administration of trehangelin-A (THG-A) is effective for metabolic disorders caused by a high-fat diet, as we previously showed that the intraperitoneal administration of THG-A improved metabolic disorders caused by a high-fat diet. Mice received a control diet or high-fat diet for eight weeks. Concurrently, mice were orally administered 0.2 ml/mouse phosphate-buffered saline (PBS) or 1 or 10 mg/0.2 ml/mouse of THG-A once daily during the experiment. The weight gain caused by a high-fat diet was significantly suppressed by oral THG-A compared to a high-fat diet without THG-A. In addition, at eight weeks after starting the diet, the increased plasma total-cholesterol (T-CHO) and low-density lipoprotein-cholesterol (LDL-C) levels caused by a high-fat diet were significantly reduced by 10 mg/mouse THG-A and tended to attenuated by 1 mg/mouse THG-A. The LDL receptor and CYP7A1 mRNA expression in liver associated with lipid metabolism for reducing plasma LDL-C levels was significantly enhanced by oral THG-A. In contrast, oral THG-A exerted no marked effects on mice fed the control diet. The dysbiosis of a high-fat diet fed mice, which is in the form of an increased Firmicutes-to-Bacteroidetes ratio, also recovered, and the high-fat diet induced decreased levels of Bacteroides and Akkermansia genera, which are beneficial microbiota against metabolic disorders, were also restored by oral THG-A. These results indicate that oral THG-A administration acts on metabolic disorders by improving the lipid metabolism and restoring beneficial microbiota to resolve high-fat diet induced dysbiosis.

Lifetime risk assessment in cholesterol management among hypertensive patients: observational cross-sectional study based on electronic health record data

BackgroundIn hypertensive patients, reducing plasma low-density lipoprotein cholesterol level (LDL-C) is one of the main interventions for preventing chronic cardiovascular diseases (CVD). However, LDL-C control remains generally insufficient, also in patients with hypertension. We analyzed Electronic Health Record (EHR) data of 7117 hypertensive patients to find the most potential age and sex subgroups in greatest need for improvement in real life dyslipidemia treatment. Taking into account the current discussion on lifetime CVD risk, we focused on the age dependence in LDL-C control.MethodsIn this observational cross-sectional study, based on routine electronic health record (EHR) data, we investigated LDL-C control of hypertensive, non-diabetic patients without renal dysfunction or CVD, aged 30 years or more in Finnish primary care setting.ResultsMore than half (54% of women and 53% of men) of untreated patients did not meet the LDL-C target of < 3 mmol/l and one third (35% of women and 33% of men) of patients did not reach the target even with the lipid-lowering medication (LLM). Furthermore, higher age was strongly associated with better LDL-C control (p < 0.001) and lower LDL-C level (p < 0.001) in individuals with and without LLM. Higher age was also strongly associated with LLM prescription (p < 0.001). In total, about half of the patients were on LLM (53% of women and 51% of men).ConclusionsOur findings indicate that dyslipidemia treatment among Finnish primary care hypertensive patients is generally insufficient, particularly in younger age groups who might benefit the most from CVD risk reduction over time. Clinicians should probably rely more on the lifetime risk of CVD, especially when treating working age hypertensive patients.