Proprotein Convertase Subtilisin/kexin Type 9 Expression Research Articles

Aerobic exercise alleviates statin-induced PCSK9 upregulation by increasing epoxyeicosatrienoic acid levels through the FoxO3a-Sirt6 axis

BackgroundStatins are the cornerstone of low-density lipoprotein cholesterol (LDL-C)-lowering therapy; however, the therapeutic efficacy of statins in countering atherosclerotic cardiovascular disease (ASCVD) is compromised by the concurrent elevation of proprotein convertase subtilisin/kexin type 9 (PCSK9), a pivotal molecule that increases LDL-C levels. Aerobic exercise lowers PCSK9 levels, but the underlying mechanism remains unclear. Therefore, we investigated how aerobic exercise can ameliorate statin-induced increases in PCSK9 levels. MethodsThree-week-old male American Institute of Cancer Research (ICR) mice were fed a high-fat-cholesterol diet (HFD) for 12 weeks and then administered atorvastatin alone or atorvastatin combined with aerobic exercise (Statin+Ex). Moreover, a total of 165 participants with stable coronary heart disease (CHD) enrolled at the inpatient and outpatient departments of the Second Xiangya Hospital of Central South University from January 2018 to July 2020 were randomized into the Statin group (male/female = 51/33) and Statin+Ex group (male/female = 52/29). Patients in the Statin+Ex group underwent treadmill exercise of 45–60 min/day for 7 days. ResultsAerobic exercise effectively alleviated statin-induced PCSK9 upregulation in human patients with CHD and hypercholesterolemic ICR mice (all p < 0.05). Mechanistically, our findings revealed that aerobic exercise induced elevated epoxyeicosatrienoic acids (EETs) plasma levels while concurrently reducing the activity of soluble epoxide hydrolase (sEH) (all p < 0.05), an enzyme responsible for EETs degradation. Further, EETs significantly suppressed PCSK9 expression, subsequently reducing the LDL-C levels (all p < 0.05); this effect was mediated via the activation of the Forkhead box O3a-Silent mating type information regulation 2 homolog 6 (FoxO3a-Sirt6) axis, with no impact on the Sterol Regulatory Element Binding Protein 2 and 3-hydroxy-3-methylglutaryl-CoA reductase (SREBP2-HMGCR) pathway. ConclusionOur study sheds light on the paradigm of “Exercise is Medicine”, providing evidence to support the use of statins combined with exercise in reducing LDL-C levels, and unveils potential avenues for clinical applications of sEH inhibitors, presenting novel prospects for therapeutic interventions in ASCVD.

Integrated bioinformatics analysis identifies PCSK9 as a prognosticator correlated with lipid metabolism in pancreatic adenocarcinoma

BackgroundPancreatic adenocarcinoma (PAAD) is the most frequent kind of pancreatic cancer (PC). Recent studies suggest that lipid metabolism facilitates tumorigenesis, disease progression, and resistance to therapy by promoting lipid synthesis, accumulation, and breakdown. Thus, exploring the lipid metabolism network could unveil novel therapeutic avenues for early detection, precision medicine, and prognostication in PAAD. This project intends to develop new lipid metabolism-related biomarkers for PAAD diagnosis and investigate the link between important genes and immune cell infiltration (ICI).MethodsTissue samples from 20 PAAD patients and 20 healthy controls were obtained. Analysis were focused on the datasets GSE71729 and GSE16515, which include samples of PAAD (n = 161) and those from healthy human tissue (n = 61), derived from the GEO database. Knockdown of PCSK9 on PC cells were conducted by si-RNA and sh-RNA. Migration and cell functional experiments were performed to assess the role of PCSK9 in cell multiplication. Furthermore, a xenograft mouse model was employed to confirm PCSK9's function in vivo.ResultsThe expression level of Proprotein convertase subtilisin/kexin type 9 (PCSK9) is significantly elevated in tissues affected by PAAD when compared to normal tissues. Survival analyses indicated that increased PCSK9 levels are inversely related to overall and disease-free survival (DFS). PCSK9’s functional annotation associated it with the cell cycle and metabolism, especially energy metabolism. Examination of ICI data determined that PCSK9 expression demonstrated an unambiguous association with the M0 macrophages, T follicular helper cells (Tfh), gamma delta T cells and activated DC, and an inverse relationship with Monocytes, CD8+ T cells, memory B cells, resting CD4+ memory T cells, activated NK cells and resting DC abundance. PCSK9 expression knockdown has the ability to impede PC cells’ migration and proliferation.ConclusionOur study identified PCSK9 as a critical gene in PAAD. Expression levels of PCSK9 varied between PAAD and normal samples. ROC analysis verified PCSK9's strong capacity to differentiate PC from normal samples. Importantly, PCSK9 expression was considerably elevated in PC cell lines and tissues. Furthermore, PCSK9 stimulates the migration and proliferation of tumor cells in vivo and vitro.

O75 INHIBITION OF PCSK9/NFAT AMELIORATES CARDIAC DYSMETABOLISM AND FIBROSIS IN EXPERIMENTAL RAT MODEL OF PCOS BY REDUCING ATHEROGENIC LIPID AND IMPROVING INSULIN SENSITIVITY

Background: Polycystic ovarian syndrome (PCOS) remains an independent risk factor of cardiovascular disease (CVD), particularly in women of child-bearing age, and contributes to global increase in the prevalence/incidence of cardiovascular mortality and morbidity in women. Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a promising therapeutic target to reduce residual CVD risk. Similarly, Nuclear factor of activated T cells (NFAT) is a transcription factor that is implicated in cardiac fibrosis. However, the role of PCSK9/NFAT in PCOS-associated cardiometabolic syndrome is not clear. Short chain fatty acids (SCFAs) play a multifaceted regulatory role in metabolic health. The present study therefore investigated the role of PCSK9/NFAT in cardiometabolic syndrome associated with experimental PCOS, and the therapeutic potential of SCFAs, especially butyrate. Material and Methods: Eight-week-old female Wistar rats were allotted into four groups (n=5). Polycystic ovarian syndrome was induced by administering letrozole (1 mg/kg p.o.) once daily for 21 days, thereafter the animals were treated with 200 mg/kg (oral gavage) of sodium butyrate for six weeks. Gene expression, biochemical parameters and cardiac/ovarian morphology were evaluated with appropriate methods. Results: Rats with PCOS showed androgen excess, multiple ovarian cysts and reduced insulin sensitivity. The rats in addition displayed atherogenic dyslipidemia (triglyceride/HDLc, TC/HDLc and LDLc), hypercorticosteronemia and elevated cardiac triglyceride, inflammatory biomarkers (NF-kappaB and TNF-alpha), caspase-6, 4-hydroxynonenal, inflammasome (NLRP3), fibrosis and depleted antioxidant defense (NrF2 and glutathione) as well as increased expression of PCSK9 and NFAT when compared to the control rats. Nevertheless, these systemic and morphological alterations were ameliorated following treatment with sodium butyrate. Conclusion: The present results collectively demonstrate cardiac dysmetabolism, inflammation, fibrosis as well as apoptosis in experimental PCOS rat model, which are driven by elevated expression of PCSK9/NFAT. The results further suggest that SCFAs, butyrate alleviates cardiometabolic syndrome and its attendant cardiomorbidity by suppression of PCSK9/NFAT. The present data provide a preclinical insight to prevention and management of CVD in PCOS individuals.

Increase of PCSK9 expression in diabetes promotes VEGFR2 ubiquitination to inhibit endothelial function and skin wound healing.

Diabetic foot ulcers (DFUs) are a serious vascular disease. Currently, no effective methods are available for treating DFUs. Pro-protein convertase subtilisin/kexin type 9 (PCSK9) regulates lipid levels to promote atherosclerosis. However, the role of PCSK9 in DFUs remains unclear. In this study, we found that the expression of PCSK9 in endothelial cells (ECs) increased significantly under high glucose (HG) stimulation and in diabetic plasma and vessels. Specifically, PCSK9 promotes the E3 ubiquitin-protein ligase NEDD4 binding to vascular endothelial growth factor receptor 2 (VEGFR2), which led to the ubiquitination of VEGFR2, resulting in its degradation and downregulation in ECs. Furthermore, PCSK9 suppresses the expression and activation of AKT, endothelial nitric oxide synthase (eNOS), and ERK1/2, leading to decreased nitric oxide (NO) production and increased superoxide anion (O2._) generation, which impairs vascular endothelial function and angiogenesis. Importantly, using evolocumab to limit the increase in PCSK9 expression blocked the HG-induced inhibition of NO production and the increase in O2._ production, as well as inhibited the phosphorylation and expression of AKT, eNOS, and ERK1/2. Moreover, evolocumab improved vascular endothelial function and angiogenesis, and promoted wound healing in diabetes. Our findings suggest that targeting PCSK9 is a novel therapeutic approach for treating DFUs.

PCSK9 inhibitor effectively alleviated cognitive dysfunction in a type 2 diabetes mellitus rat model.

The incidence of diabetes-associated cognitive dysfunction (DACD) is increasing; however, few clinical intervention measures are available for the prevention and treatment of this disease. Research has shown that proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, particularly SBC-115076, have a protective effect against various neurodegenerative diseases. However, their role in DACD remains unknown. In this study, we aimed to explore the impact of PCSK9 inhibitors on DACD. Male Sprague-Dawley (SD) rats were used to establish an animal model of type 2 diabetes mellitus (T2DM). The rats were randomly divided into three groups: the Control group (Control, healthy rats, n = 8), the Model group (Model, rats with T2DM, n = 8), and the PCSK9 inhibitor-treated group (Treat, T2DM rats treated with PCSK9 inhibitors, n = 8). To assess the spatial learning and memory of the rats in each group, the Morris water maze (MWM) test was conducted. Hematoxylin-eosin staining and Nissl staining procedures were performed to assess the structural characteristics and functional status of the neurons of rats from each group. Transmission electron microscopy was used to examine the morphology and structure of the hippocampal neurons. Determine serum PCSK9 and lipid metabolism indicators in each group of rats. Use qRT-PCR to detect the expression levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) in the hippocampal tissues of each group of rats. Western blot was used to detect the expression of PCSK9 and low-density lipoprotein receptor (LDLR) in the hippocampal tissues of rats. In addition, a 4D label-free quantitative proteomics approach was used to analyse protein expression in rat hippocampal tissues. The expression of selected proteins in hippocampal tissues was verified by parallel reaction monitoring (PRM) and immunohistochemistry (IHC). The results showed that the PCSK9 inhibitor alleviated cognitive dysfunction in T2DM rats. PCSK9 inhibitors can reduce PCSK9, total cholesterol (TC), and low-density lipoprotein (LDL) levels in the serum of T2DM rats. Meanwhile, it was found that PCSK9 inhibitors can reduce the expression of PCSK9, IL-1β, IL-6, and TNF-α in the hippocampal tissues of T2DM rats, while increasing the expression of LDLR. Thirteen potential target proteins for the action of PCSK9 inhibitors on DACD rats were identified. PRM and IHC revealed that PCSK9 inhibitors effectively counteracted the downregulation of transthyretin in DACD rats. This study uncovered the target proteins and specific mechanisms of PCSK9 inhibitors in DACD, providing an experimental basis for the clinical application of PCSK9 inhibitors for the potential treatment of DACD.

Proprotein convertase subtilisin/kexin type 9 as a drug target for abdominal aortic aneurysm.

There are no current drug therapies to limit abdominal aortic aneurysm (AAA) growth. This review summarizes evidence suggesting that inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) may be a drug target to limit AAA growth. Mendelian randomization studies suggest that raised LDL and non-HDL-cholesterol are causal in AAA formation. PCSK9 was reported to be upregulated in human AAA samples compared to aortic samples from organ donors. PCSK9 gain of function viral vectors promoted aortic expansion in C57BL/6 mice infused with angiotensin II. The effect of altering PCSK9 expression in the aortic perfusion elastase model was reported to be inconsistent. Mutations in the gene encoding PCSK9, which increase serum cholesterol, were associated with increased risk of human AAA. Patients with AAA also have a high risk of cardiovascular death, myocardial infarction and stroke. Recent research suggests that PCSK9 inhibition would substantially reduce the risk of these events. Past research suggests that drugs that inhibit PCSK9 have potential as a novel therapy for AAA to both limit aneurysm growth and reduce risk of cardiovascular events. A large multinational randomized controlled trial is needed to test if PCSK9 inhibition limits AAA growth and cardiovascular events.

Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Is Associated With Recurrence and Survival of Resectable Non–Small Cell Lung Cancer (NSCLC): A Retrospective Study

IntroductionCurative lung resection remains the key therapeutic strategy for early-stage non–small cell lung cancer (NSCLC). However, a proportion of patients still experience variable outcomes and eventually develop recurrence or die from their disease. Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been identified as a deleterious factor that inhibits tumor cells apoptosis and leads to reduction of lymphocyte infiltration. However, there has been no research on the predicted role of PCSK9 as an immunohistochemical biomarker with survival in resectable NSCLC. MethodsOne hundred sixty-three patients with resectable NSCLC were retrospectively reviewed, and PCSK9 expression of resected NSCLC was analyzed by immunohistochemistry using tissue microarrays. ResultsPCSK9 was associated with recurrence (42.1% relapsed in the PCSK9lo group versus 57.9% relapsed in the PCSK9hi group, P = 0.006) and survival status (39.6% dead in PCSK9lo group versus 60.4% dead in PCSK9hi group, P = 0.004) in patients with resectable NSCLC. Moreover, resectable NSCLC patients with higher PCSK9 expression in tumor tissue experienced poorer disease-free survival (median disease-free survival: 10.5 versus 25.2 mo, hazard ratio = 1.620, 95% confidence interval: 1.124-2.334) and overall suvrival (median overall suvrival: 20.0 versus 54.1 mo, hazard ratio = 1.646, 95% confidence interval: 1.101-2.461) compared to those with lower PCSK9 expression. ConclusionsHigh PCSK9 expression of tumor was correlated with recurrence and worse survival status of resectable NSCLC in our retrospective study, which indicated that PCSK9 in NSCLC may be an immunohistochemical biomarker of poor prognosis for patients with resectable NSCLC. Further large-scale prospective studies are warranted to establish these results.

Chemical constituents from the roots of Cynanchum wilfordii with PCSK9 secretion inhibitory activities

From the Cynanchum wilfordii roots, 32 compounds, including 5 previously undescribed (1, 4–6, 12) and 27 known (2, 3, 7–11, 13–32) compounds, were isolated, and their structures were elucidated using NMR spectroscopic data and MS data aided by ECD calculations or the modified Mosher's reaction. All isolates were tested for their inhibitory effects on proprotein convertase subtilisin/kexin type 9 (PCSK9) secretion. Among the isolates, compound 4, a methyl cholesterol analog, exhibited the most potent effect in reducing PCSK9 secretion, along with PCSK9 downregulation at the mRNA and protein levels via FOXO1/3 upregulation. Moreover, compound 4 attenuated statin-induced PCSK9 expression and enhanced the uptake of DiI-LDL low-density lipoprotein. Thus, compound 4 is suggested to be a potential candidate for controlling cholesterol levels.

The role of PCSK9 in glomerular lipid accumulation and renal injury in diabetic kidney disease.

Glomerular lipid accumulation is a defining feature of diabetic kidney disease (DKD); however, the precise underlying mechanism requires further elucidation. Recent evidence suggests a role for proprotein convertase subtilisin/kexin type 9 (PCSK9) in intracellular lipid homeostasis. Although PCSK9 is present in kidneys, its role within kidney cells and relevance to renal diseases remain largely unexplored. Therefore, we investigated the role of intracellular PCSK9 in regulating lipid accumulation and homeostasis in the glomeruli and podocytes under diabetic conditions. Furthermore, we aimed to identify the pathophysiological mechanisms responsible for the podocyte injury that is associated with intracellular PCSK9-induced lipid accumulation in DKD. In this study, glomeruli were isolated from human kidney biopsy tissues, and glomerular gene-expression analysis was performed. Also, db/db and db/m mice were used to perform glomerular gene-expression profiling. We generated DKD models using a high-fat diet and low-dose intraperitoneal streptozocin injection in C57BL/6 and Pcsk9 knockout (KO) mice. We analysed cholesterol and triacylglycerol levels within the kidney cortex. Lipid droplets were evaluated using BODIPY staining. We induced upregulation and downregulation of PCSK9 expression in conditionally immortalised mouse podocytes using lentivirus and siRNA transfection techniques, respectively, under diabetic conditions. A significant reduction in transcription level of PCSK9 was observed in glomeruli of individuals with DKD. PCSK9 expression was also reduced in podocytes of animals under diabetic conditions. We observed significantly higher lipid accumulation in kidney tissues of Pcsk9 KO DKD mice compared with wild-type (WT) DKD mice. Additionally, Pcsk9 KO mouse models of DKD exhibited a significant reduction in mitochondria number vs WT models, coupled with a significant increase in mitochondrial size. Moreover, albuminuria and podocyte foot process effacement were observed in WT and Pcsk9 KO DKD mice, with KO DKD mice displaying more pronounced manifestations. Immortalised mouse podocytes exposed to diabetic stimuli exhibited heightened intracellular lipid accumulation, mitochondrial injury and apoptosis, which were ameliorated by Pcsk9 overexpression and aggravated by Pcsk9 knockdown in mouse podocytes. The downregulation of PCSK9 in podocytes is associated with lipid accumulation, which leads to mitochondrial dysfunction, cell apoptosis and renal injury. This study sheds new light on the potential involvement of PCSK9 in the pathophysiology of glomerular lipid accumulation and podocyte injury in DKD.

MiR-181d-5p ameliorates hypercholesterolemia by targeting PCSK9.

Hypercholesterolemia is an independent risk factor for cardiovascular disease and lowering circulating levels of low-density lipoprotein cholesterol (LDL-C) can prevent and reduce cardiovascular events. MicroRNA-181d (miR-181d) can reduce the levels of triglycerides and cholesterol esters in cells. However, it is not known whether miR-181d-5p can lower levels of circulating LDL-C. Here, we generated two animal models of hypercholesterolemia to analyze the potential relationship between miR-181d-5p and LDL-C. In hypercholesterolemia model mice, adeno-associated virus (AAV)-mediated liver-directed overexpression of miR-181d-5p decreased the serum levels of cholesterol and LDL-C and the levels of cholesterol and triglyceride in the liver compared with control mice. Target Scan 8.0 indicated Proprotein convertase subtilisin/kexin type 9 (PCSK9) to be a possible target gene of miR-181d-5p, which was confirmed by in vitro experiments. miR-181d-5p could directly interact with both the PCSK9 3'-UTR and promoter to inhibit PCSK9 translation and transcription. Furthermore, Dil-LDL uptake assays in PCSK9 knockdown Huh7 cells demonstrated that miR-181d-5p promotion of LDL-C absorption was dependent on PCSK9. Collectively, our findings show that miR-181d-5p targets the PCSK9 3'-UTR to inhibit PCSK9 expression and to reduce serum LDL-C. miR-181d-5p is therefore a new therapeutic target for the development of anti-hypercholesterolemia drugs.

Far-infrared irradiation increases the uptake of LDL cholesterol by downregulating PCSK9 through the activation of TRPV4 calcium channels in HepG2 cells

This study investigated the effects of far-infrared (FIR) irradiation on low-density lipoprotein cholesterol (LDL-C) uptake by human hepatocellular carcinoma G2 (HepG2) cells via the regulation of proprotein convertase subtilisin/kexin type 9 (PCSK9). FIR irradiation for 30 min significantly decreased PCSK9 expression (p < 0.01) in HepG2 cells. FIR irradiation substantially increased the low-density lipoprotein receptor (p < 0.0001) and LDL-C uptake (p < 0.01). Activation of transient receptor potential vanilloid (TRPV) channels mimicked the effects of FIR irradiation, significantly decreasing the protein expression of PCSK9 (p < 0.05). Conversely, inhibition of TRP channels using ruthenium red reversed the reduction in PCSK9 protein expression following FIR irradiation (p < 0.01). The specific activation of TRPV4 using 4α-PDD mimicked the effect of FIR irradiation (p < 0.01), whereas PCSK9 reduction by FIR irradiation was significantly reversed by the inhibition of TRPV4 using RN1734 (p < 0.05). These findings implied that FIR irradiation emitted from a ceramic lamp specifically increased TRPV4 activity. These findings provide insights into a novel therapeutic approach using FIR irradiation for LDL-C regulation and its implications for cardiovascular health.

Metformin-Induced Proprotein Convertase Subtilisin/Kexin Type 9 Inhibition Further Decreases Low-Density Lipoprotein Cholesterol Following Statin Treatment in Patients With Coronary Artery Disease and Without Diabetes.

In vitro investigations have established metformin's capacity to downregulate proprotein convertase subtilisin/kexin type 9 (PCSK9) expression, suggesting a potential beneficial effect on atherogenic lipoprotein particles when combined with metformin therapy. Our objective was to assess whether metformin could mitigate statin-induced adverse effects on PCSK9, thereby improving lipid profiles in patients with coronary artery disease (CAD) but without diabetes. Employing an open-label, placebo-controlled, randomized trial, we randomized patients with CAD but without diabetes into CLA (cholesterol-lowering agents alone: atorvastatin±ezetimibe, n = 38) and Met + CLA groups (metformin plus CLA, n = 33) in a 1:1 ratio. The primary end point was the therapeutic impact of 1-month metformin combination treatment on low-density lipoprotein cholesterol (LDL-C) and PCSK9 levels. Baseline LDL-C and PCSK9 levels were 76.18 mg·dL -1 and 80.54 ng·mL -1 , respectively. After 1 month, metformin significantly reduced LDL-C (-20.81%, P < 0.001), enabling 72% of patients to attain guideline-recommended LDL-C goals. Noteworthy reductions in PCSK9 levels (-15.03%, P < 0.001) were observed. Moreover, Met + CLA markedly reduced LDL particle number more than CLA alone (-10.65% vs. 1.45%, P = 0.009), primarily due to diminished small-dense LDL particle count. Mechanistically, our study demonstrated metformin's inhibition of statin-induced PCSK9 expression in human hepatocellular cells. In summary, a 1-month metformin combination regimen reduced LDL-C levels in patients with CAD but without diabetes by inhibiting PCSK9 expression. Chinese Clinical Trial Registry identifier: ChiCTR1900026925 (26/10/2019).

Abstract 3071: Ras-related Protein 1a-mediated Regulation Of Proprotein Convertase Subtilisin/kexin Type 9

Background &amp; Aims: Proprotein convertase subtilisin/kexin type 9 (PCSK9) has recently been identified as a therapeutic target to regulate plasma low-density lipoprotein cholesterol (LDL-C) levels. PCSK9 binds to the LDL receptor (LDLR) and targets it for lysosomal degradation, hindering LDL-C uptake from the circulation. Despite the use of anti-PCSK9 therapies, the molecular mechanisms by which PCSK9 gets regulated are not fully understood. In this regard, we recently discovered that activation of hepatic small GTPase, Ras-related protein 1a (Rap1a), decreases PCSK9 levels and subsequently lowers plasma LDL-C. In addition, the most widely used medicine to lower cholesterol, statins, have been shown to increase circulating PCSK9 levels, which limits their efficacy; however, our understanding of the link between statins and plasma PCSK9 is limited. Hypothesis &amp; Aims: As statins block the synthesis of geranylgeranyl isoprenoids (GGPP), which are required for Rap1a activation, we explored the hypothesis that Rap1a is involved in statin-induced expression of PCSK9. We further explored the mechanisms of PCSK9 regulation by Rap1a. Methods: Mice were treated orally with statins and geranylgeraniol, the precursor of GGPP by daily oral gavage. Rap1a activator, 8-pCPT-2’-OMe-cAMP, was administered via i.p. injection. Hepatic PCSK9, plasma PCSK9, and LDL-C levels were assayed. For in vitro experiments, primary hepatocytes were isolated from wild-type mice and treated with vehicle, simvastatin, or simvastatin in combination with GGPP or 8-pCPT-2’-OMe-cAMP. PCSK9 levels were measured. Results: Statin treatment combined with GGOH lowered plasma PCSK9 and LDL-C in mice (174 ± 25 vs 109 ± 16 ng/mL and 24 ± 1.8 vs 19 ± 1.4 mg/dL, respectively, n=4-5, mean ± SEM, p &lt; 0.05). Rap1a activator, 8-pCPT-2’-OMe-cAMP, also lowered statin-induced PCSK9 in vitro. Mechanistically, we found that Rap1a inhibits the downstream RhoA-ROCK pathway and regulates PCSK9 at the post-transcriptional level. Conclusions: In conclusion, our data reveal that Rap1a is a novel regulator of PCSK9 protein and blocking Rap1a prenylation through lowering geranylgeranyl levels contributes to statin-mediated induction of PCSK9.

Exploring the potential of pomegranate (Punica granatum) peel extract and punicalagin as novel anti-hypercholesterolemic agents

Background: Hypercholesterolemia, characterized by elevated low-density lipoprotein (LDL) cholesterol levels, is a significant risk factor for cardiovascular diseases. Familial and behavioral factors contribute to its onset, and while lifestyle changes offer some benefits, medical interventions are essential to manage this condition effectively. Statins, the primary medications used to lower LDL cholesterol, have limitations, including the unintended upregulation of proprotein convertase subtilisin/kexin type 9 (PCSK9). Therefore, exploring alternative approaches to enhance LDL receptor expression while targeting PCSK9 is crucial, with herbal medicine showing promise in this endeavor. Objective: This study investigates the potential of pomegranate peel extract and punicalagin, a key pomegranate component, in lowering LDL cholesterol in HepG2 cells. The research explores their effects on LDL receptor (LDLR) expression, LDL uptake, and proprotein convertase subtilisin/kexin type 9 (PCSK9) gene expression. Methods: HepG2 cells were treated with different concentrations of pomegranate peel extract (37.5, 75, 150, and 300 μg/ml) and punicalagin (12.5, 25, 50, and 100 μg/ml). Next, the viability of HepG2 cells, the protein levels of LDL receptors and LDL uptake, and the expression levels of PCSK9 were measured. Results: Pomegranate peel extract (37.5, 75, 150, and 300 μg/ml) and punicalagin (12.5, 25, 50, and 100 μg/ml) did not exhibit significant cytotoxicity and significantly increased LDLR protein levels (P-value= 0.00, after 24 hours) and LDL cholesterol uptake (P-value= 0.00, after 24 hours). Furthermore, they exhibited a dose-dependent reduction in the expression of PCSK9 (pomegranate: P-value= 0.01; punicalagin: P-value= 0.00). Conclusion: These findings suggest that pomegranate peel extract and punicalagin have the potential to serve as effective agents in managing hypercholesterolemia by enhancing LDL receptor expression and reducing PCSK9 expression in HepG2 cells. Further research is required to explore their effects on transcription factors and PCSK9 function. Keywords: Pomegranate; Punicalagin; HepG2 cell; LDL; Cardiovascular; Punica granatum

PCSK9 inhibition attenuates alcohol-associated neuronal oxidative stress and cellular injury

Alcohol Use Disorder (AUD) is a persistent condition linked to neuroinflammation, neuronal oxidative stress, and neurodegenerative processes. While the inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) has demonstrated effectiveness in reducing liver inflammation associated with alcohol, its impact on the brain remains largely unexplored. This study aimed to assess the effects of alirocumab, a monoclonal antibody targeting PCSK9 to lower systemic low-density lipoprotein cholesterol (LDL-C), on central nervous system (CNS) pathology in a rat model of chronic alcohol exposure. Alirocumab (50 mg/kg) or vehicle was administered weekly for six weeks in 32 male rats subjected to a 35 % ethanol liquid diet or a control liquid diet (n = 8 per group). The study evaluated PCSK9 expression, LDL receptor (LDLR) expression, oxidative stress, and neuroinflammatory markers in brain tissues. Chronic ethanol exposure increased PCSK9 expression in the brain, while alirocumab treatment significantly upregulated neuronal LDLR and reduced oxidative stress in neurons and brain vasculature (3-NT, p22phox). Alirocumab also mitigated ethanol-induced microglia recruitment in the cortex and hippocampus (Iba1). Additionally, alirocumab decreased the expression of pro-inflammatory cytokines and chemokines (TNF, CCL2, CXCL3) in whole brain tissue and attenuated the upregulation of adhesion molecules in brain vasculature (ICAM1, VCAM1, eSelectin). This study presents novel evidence that alirocumab diminishes oxidative stress and modifies neuroimmune interactions in the brain elicited by chronic ethanol exposure. Further investigation is needed to elucidate the mechanisms by which PCSK9 signaling influences the brain in the context of chronic ethanol exposure.

Analyzing the causal relationship between lipid-lowering drug target genes and epilepsy: a Mendelian randomization study.

Previous research has yielded conflicting results on the link between epilepsy risk and lipid-lowering medications. The aim of this study is to determine whether the risk of epilepsy outcomes is causally related to lipid-lowering medications predicted by genetics. We used genetic instruments as proxies to the exposure of lipid-lowering drugs, employing variants within or near genes targeted by these drugs and associated with low-density lipoprotein cholesterol (LDL cholesterol) from a genome-wide association study. These variants served as controlling factors. Through drug target Mendelian randomization, we systematically assessed the impact of lipid-lowering medications, including HMG-CoA reductase (HMGCR) inhibitors, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, and Niemann-Pick C1-like 1 (NPC1L1) inhibitors, on epilepsy. The analysis demonstrated that a higher expression of HMGCR was associated with an elevated risk of various types of epilepsy, including all types (OR = 1.17, 95% CI:1.03 to 1.32, p = 0.01), focal epilepsy (OR = 1.24, 95% CI:1.08 to 1.43, p = 0.003), and focal epilepsy documented with lesions other than hippocampal sclerosis (OR = 1.05, 95% CI: 1.01 to 1.10, p = 0.02). The risk of juvenile absence epilepsy (JAE) was also associated with higher expression of PCSK9 (OR = 1.06, 95% CI: 1.02 to 1.09, p = 0.002). For other relationships, there was no reliable supporting data available. The drug target MR investigation suggests a possible link between reduced epilepsy vulnerability and HMGCR and PCSK9 inhibition.

Correlation of potential diagnostic biomarkers (circulating miRNA and protein) of bipolar II disorder

ObjectivesWe previously identified certain peripheral biomarkers of bipolar II disorder (BD-II) including circulating miRNAs (miR-7-5p, miR-142–3p, miR-221–5p, and miR-370–3p) and proteins (Matrix metallopeptidase 9 (MMP9), phenylalanyl-tRNA synthetase subunit beta (FARSB), peroxiredoxin 2 (PRDX2), carbonic anhydrase 1 (CA-1), and proprotein convertase subtilisin/kexin type 9 (PCSK9)). We try to explore the connection between these biomarkers. MethodsWe explored correlations between the peripheral levels of above circulating miRNAs and proteins in our previously collected BD-II (N = 96) patients and control (N = 115) groups. We further searched TargetScan and BioGrid websites to identify direct and indirect interactions between these protein-coding genes and circulating miRNAs. ResultsIn the BD-II group, we identified significant correlations between the miR-221–5p and CA-1 (rho = −0.323, P = 0.001), FARSB (rho = 0.251, P = 0.014), MMP-9 (rho = 0.313, P = 0.002) and PCSK9 (rho = 0.252, P = 0.014). The miR-370–3p also significantly correlated with FARSB expression (rho = 0.330, P = 0.001) and PCSK9 expression (rho = 0.221, P = 0.031) in the BD-II group. Our findings were in line with the modulating axis identified from TargetScan and BioGrid, miR-221–5p/CA-1/MMP9 and miR-370–3p/FARSB/PCSK9, suggesting their association with BD-II. ConclusionOur result supported that peripheral candidate miRNA and protein biomarkers may interact in BD-II. We concluded that miR-221–5p/CA-1/MMP9 and miR-370–3p/FARSB/PCSK9 axes might act a critical role in the pathomechanism of BD-II.

Geranylgeranyl isoprenoids and hepatic Rap1a regulate basal and statin-induced expression of PCSK9

LDL-C lowering is the main goal of atherosclerotic cardiovascular disease prevention, and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition is now a validated therapeutic strategy that lowers serum LDL-C and reduces coronary events. Ironically, the most widely used medicine to lower cholesterol, statins, has been shown to increase circulating PCSK9 levels, which limits their efficacy. Here, we show that geranylgeranyl isoprenoids and hepatic Rap1a regulate both basal and statin-induced expression of PCSK9 and contribute to LDL-C homeostasis. Rap1a prenylation and activity is inhibited upon statin treatment, and statin-mediated PCSK9 induction is dependent on geranylgeranyl synthesis and hepatic Rap1a. Accordingly, treatment of mice with a small-molecule activator of Rap1a lowered PCSK9 protein and plasma cholesterol and inhibited statin-mediated PCSK9 induction in hepatocytes. The mechanism involves inhibition of the downstream RhoA-ROCK pathway and regulation of PCSK9 at the post-transcriptional level. These data further identify Rap1a as a novel regulator of PCSK9 protein and show that blocking Rap1a prenylation through lowering geranylgeranyl levels contributes to statin-mediated induction of PCSK9.

PCSK9 increases vulnerability of carotid plaque by promoting mitochondrial dysfunction and apoptosis of vascular smooth muscle cells.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been recognized as a novel lipid-lowing target. Recent clinical studies suggested the value of inhibiting PCSK9 in decreasing the vulnerability of coronary plaques. However, the evidence of PCSK9-regulated evolution of unstable carotid plaques is unclear, which has limited the use of PCSK9 inhibitor in carotid plaques. This study aimed to determine the effect and molecular mechanisms of PCSK9 on vulnerability of carotid plaques, to provide potential therapeutic targets for stabilizing carotid plaques. The expression of PCSK9 in stable and unstable carotid plaques were examined in tissue and plasma. Human aortic vascular smooth muscle cells (VSMCs) and carotid VSMCs were employed to transfect lentivirus for overexpression and knockdown of PCSK9, respectively. Morphological and functional changes of mitochondria were observed by live-cell imaging. Cell apoptosis was evaluated by propidium iodide staining. RNA-sequencing and biological examinations were performed to explore and validate the underlying mechanisms. Truncated plasmids were employed to identify the functional domain of PCSK9 in regulation of VSMCs' mitochondrial morphology, function and apoptosis. Clinically, PCSK9 was closely related with vulnerability of human carotid plaques. Increased expression of PCSK9 in human VSMCs was accompanied by higher level of apoptosis. At subcellular level of VSMCs, the morphology of mitochondria was shifted toward the fission state, followed by mitochondrial dysfunction. Inhibition of p38 MAPK activation partially rescued the above morphological and behavioral changes caused by PCSK9. Furthermore, inhibiting of dynamin-related protein 1 (DRP1) attenuated PCSK9-related mitochondrial dysfunction and cell apoptosis. The 1-149aa domain of PCSK9 protein was essential to achieve functional regulation to VSMCs. Our findings demonstrated that PCSK9 induced morphology-related mitochondrial dysfunction and apoptosis of VSMCs, which may be related to increased vulnerability of carotid plaque.

Natural phytochemicals as small-molecule proprotein convertase subtilisin/kexin type 9 inhibitors.

A decrease in the levels of low-density lipoprotein receptors (LDLRs) leads to the accumulation of LDL cholesterol (LDL-C) in the bloodstream, resulting in hypercholesterolemia and atherosclerotic cardiovascular diseases. Increasing the expression level or inducing the activity of LDLR in hepatocytes can effectively control hypercholesterolemia. Proprotein convertase subtilisin/kexin type 9 (PCSK9) protein, primarily produced in the liver, promotes the degradation of LDLR. Inhibiting the expression and/or function of PCSK9 can increase the levels of LDLR on the surface of hepatocytes and promote LDL-C clearance from the plasma. Thus, targeting PCSK9 represents a new strategy for developing preventive and therapeutic interventions for hypercholesterolemia. Currently, monoclonal antibodies are used as PCSK9 inhibitors in clinical practice. However, the need for oral and affordable anti-PCSK9 medications limits the perspective of choosing PCSK9 inhibitors for clinical usage. Emerging research reports have demonstrated that natural phytochemicals have efficacy in maintaining cholesterol stability and regulating lipid metabolism. Developing novel natural phytochemical PCSK9 inhibitors can serve as a starting point for developing small-molecule drugs to reduce plasma LDL-C levels in patients. In this review, we summarize the current literature on the critical role of PCSK9 in controlling LDLR degradation and hypercholesterolemia, and we discuss the results of studies attempting to develop PCSK9 inhibitors, with an emphasis on the inhibitory effects of natural phytochemicals on PCSK9. Furthermore, we provide insight into the mechanisms of action by which the reported phytochemicals exert their potential PCSK9 inhibitory effects against hypercholesterolemia.