PCSK9 Inhibitors in Hyperlipidemia: Current Status and Clinical Outlook

Selective modulator of nuclear receptor PPARγ with reduced adipogenic potential ameliorates experimental nephrotic syndrome

Glomerular disease manifests as nephrotic syndrome (NS) with high proteinuria and comorbidities, and is frequently refractory to standard treatments. We hypothesized that a selective modulator of PPARγ, GQ-16, will provide therapeutic advantage over traditional PPARγ agonists for NS treatment. We demonstrate in a pre-clinical NS model that proteinuria is reduced with pioglitazone to 64%, and robustly with GQ-16 to 81% of nephrosis, comparable to controls. Although both GQ-16 and pioglitazone restore glomerular-Nphs1, hepatic-Pcsk9 and serum-cholesterol, only GQ-16 restores glomerular-Nrf2, and reduces hypoalbuminemia and hypercoagulopathy. GQ-16 and pioglitazone restore common and distinct glomerular gene expression analyzed by RNA-seq and induce insulin sensitizing adipokines to various degrees. Pioglitazone but not GQ-16 induces more lipid accumulation and aP2 in adipocytes and white adipose tissue. We conclude that selective modulation of PPARγ by a partial agonist, GQ-16, is more advantageous than pioglitazone in reducing proteinuria, NS associated comorbidities, and adipogenic side effects of full PPARγ agonists.

Based on Network Pharmacology and RNA Sequencing Techniques to Explore the Molecular Mechanism of Huatan Jiangzhuo Decoction for Treating Hyperlipidemia

Background

Hyperlipidemia, due to the practice of unhealthy lifestyles of modern people, has been a disturbance to a large portion of population worldwide. Recently, several scholars have turned their attention to Chinese medicine (CM) to seek out a lipid-lowering approach with high efficiency and low toxicity. This study aimed to explore the mechanism of Huatan Jiangzhuo decoction (HTJZD, a prescription of CM) in the treatment of hyperlipidemia and to determine the major regulation pathways and potential key targets involved in the treatment process.

Methods

Data on the compounds of HTJZD, compound-related targets (C-T), and known disease-related targets (D-T) were collected from databases. The intersection targets (I-T) between C-T and D-T were filtered again to acquire the selected targets (S-T) according to the specific index. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, as well as network construction, were applied to predict the putative mechanisms of HTJZD in treating hyperlipidemia. Thereafter, an animal experiment was conducted to validate the therapeutic effect of HTJZD. In addition, regulated differentially expressed genes (DEGs) were processed from the RNA sequencing analysis results. Common genes found between regulated DEGs and S-T were analyzed by KEGG pathway enrichment to select the key targets. Lastly, key targets were validated by real-time quantitative reverse transcription PCR (qRT-PCR) analysis.

Results

A total of 210 S-T were filtered out for enrichment analysis and network construction. The enrichment results showed that HTJZD may exert an effect on hyperlipidemia through the regulation of lipid metabolism and insulin resistance. The networks predict that the therapeutic effect of HTJZD may be based on the composite pharmacological action of these active compounds. The animal experiment results verify that HTJZD can inhibit dyslipidemia in rats with hyperlipidemia, suppress lipid accumulation in the liver, and reverse the expression of 202 DEGs, which presented an opposite trend in the model and HTJZD groups. Six targets were selected from the common targets between 210 S-T and 202 regulated DEGs, and the qRT-PCR results showed that HTJZD could effectively reverse Srebp-1c, Cyp3a9, and Insr mRNA expression (P < 0.01).

Conclusion

In brief, network pharmacology predicted that HTJZD exerts a therapeutic effect on hyperlipidemia. The animal experimental results confirmed that HTJZD suppressed the pathological process induced by hyperlipidemia by regulating the expression of targets involved in lipid metabolism and insulin resistance.

Successful treatment of cholesterol crystal embolism with anti-proprotein convertase subtilisin/kexin type 9 (PCSK9) antibody: a case report

Background

We report a unique case of renal cholesterol crystal embolism (CCE) induced by carotid artery stenting that was successfully treated with evolocumab, a fully human monoclonal antibody against proprotein convertase subtilisin kexin type 9 (PCSK9).

Case presentation

A 77-year-old man with hypertension, hyperlipidemia, and chronic kidney disease was referred to our department for decreased estimated glomerular filtration rate (eGFR)—from 32.0 to 13.9 mL/min/1.73 m²—5 weeks after carotid artery stenting. Further examination revealed livedo reticularis in the bilateral toes and eosinophilia (723/μL). Skin biopsy from livedo reticularis tissue in the bilateral toes showed cholesterol clefts in the small arteries. The patient was therefore diagnosed with CCE. After 25 weeks’ administration of evolocumab at a dose of 140 mg subcutaneously administered every 2 weeks, his eGFR had improved from 10.7 to 18.1 mL/min/1.73 m².

Conclusion

Evolocumab may have a beneficial effect on renal involvement in patients with CCE.

Progress of research on dyslipidemia accompanied by nephrotic syndrome

Nephrotic syndrome is a relatively common clinical disease. Associated dyslipidemia is a risk factor for the occurrence and development of cardiovascular and renal diseases that might gradually develop into atherosclerosis, glomerulosclerosis or tubulointerstitial injury. It also confers an elevated risk of complications such as thromboembolism. If not properly controlled over the long term, dyslipidemia will become a key factor in a poor prognosis. Furthermore, dyslipidemia correlates with an increase in hepatic compensatory synthetic lipoprotein levels and a decrease in lipoprotein clearance, which can be sourced to the downregulation of hepatic and lipoprotein lipase activities in endothelial cells, muscle, and adipose tissue, and clinically characterized as hypertriglyceridemia or hypercholesterolemia. However, further investigations into the mechanism(s) of dyslipidemia are needed, with the resultant detailed perspectives and analyses substantially aiding the further development of treatment guidelines. Currently, statins represent the most popular type of pharmaceutical intervention because they lower hepatic cholesterol production and promote the absorption of low-density lipoprotein-cholesterol from the bloodstream, followed by second-line and other potential therapies to regulate the expression of specific receptors.

Aloe-emodin exerts cholesterol-lowering effects by inhibiting proprotein convertase subtilisin/kexin type 9 in hyperlipidemic rats

Hyperlipidemia (HPL) characterized by metabolic disorder of lipids and cholesterol is one of the important risk factors for cardiovascular diseases. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent circulating regulator of LDL through its ability to induce degradation of the low-density lipoprotein cholesterol receptor (LDLR) in the lysosome of hepatocytes. Aloe-emodin (AE) is one of potentially bioactive components of Chinese traditional medicine Daming capsule. In this study we evaluated the HPL-lowering efficacy of AE in both in vivo and in vitro HPL models. High-fat diet-induced rats were treated with AE (100 mg/kg per day, ig) for 6 weeks. We found that AE administration significantly decreased the levels of total cholesterol (TC) and LDL in the serum and liver tissues. Moreover, AE administration ameliorated HPL-induced hepatic lipid aggregation. But AE administration did not significantly inhibit HMG-CoA reductase activity in the liver of HPL rats. A cellular model of HPL was established in human hepatoma (HepG2) cells treated with cholesterol (20 μg/mL) and 25-hydroxycholesterol (2 μg/mL), which exhibited markedly elevated cholesterol levels. The increased cholesterol levels could be reversed by subsequent treatment with AE (30 μM). In both the in vivo and in vitro HPL models, we revealed that AE selectively suppressed the sterol-regulatory element-binding protein-2 (SREBP-2) and hepatocyte nuclear factor (HNF)1α-mediated PCSK9 signaling, which in turn upregulated LDL receptor (LDLR) and promoted LDL uptake. This study demonstrates that AE reduces cholesterol content in HPL rats by inhibiting the hepatic PCSK9/LDLR pathway.

Ezetimibe in high-risk, previously treated statin patients: a systematic review and network meta-analysis of lipid efficacy

PURPOSE

While statins are used as first-line treatments for high-risk patients with hypercholesterolemia, statin monotherapy is often insufficient to achieve target low-density lipoprotein cholesterol (LDL-C) levels. Second-line treatment options include up-titration of statin dose, switching to a more potent statin, or combination therapy, e.g., with ezetimibe. The aim of this study was to evaluate the efficacy of adding ezetimibe to simvastatin, atorvastatin, or rosuvastatin monotherapy versus doubling the dosage or switching to a higher-potency statin in a population of patients with hypocholesterolemia at high risk of cardiovascular disease (CVD) and who had been previously treated with a statin.

METHODS

A systematic literature search was performed and evidence bases were established for populations of atorvastatin-, simvastatin-, and rosuvastatin-experienced patients using eligible randomized controlled trials (RCTs). Based on the available data, we constructed networks of evidence and conducted a Bayesian network meta-analysis (NMA) within each statin population. The primary outcome of interest was percent change from baseline in LDL-C. Changes in total cholesterol were explored as a secondary outcome.

FINDINGS

Across all patient populations, 35 RCTs were identified and included in the evidence base. Among patients on simvastatin therapy, the addition of ezetimibe resulted in a mean difference (MD) in LDL-C of - 13.62% (95% CrI - 19.99, - 6.91; see table below) compared to doubling the starting dose of simvastatin. In the population of patients on atorvastatin therapy, the addition of ezetimibe resulted in an MD in LDL-C of - 14.71% (95% CrI - 16.46, - 12.95) compared to doubling the starting dose of atorvastatin. The addition of ezetimibe to rosuvastatin resulted in an MD in LDL-C of - 14.96% (95% CrI - 17.79, - 12.11), compared to doubling the starting rosuvastatin dose. Similar trends were observed for changes in total cholesterol.

IMPLICATIONS

Given the available data, the addition of ezetimibe to ongoing simvastatin, atorvastatin, or rosuvastatin monotherapy offers greater reduction in LDL-C among patients at high risk of CVD compared to doubling the initial statin dose.

Implications of GLAGOV study

PURPOSE OF REVIEW

Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibition has emerged as a novel approach to lowering levels of low-density lipoprotein cholesterol (LDL-C). The impact of PCSK9 inhibition in statin-treated patients on coronary atherosclerosis had remained unknown.

RECENT FINDINGS

The GLAGOV trial compared the effect of the PCSK9 inhibitor, evolocumab, and placebo on progression of coronary atherosclerosis in patients treated with at least moderate intensity statin therapy. Predictable lowering of LDL-C with evolocumab (36.6 versus 93.0 mg/dl) associated with significant regression of coronary atherosclerosis. A direct relationship was observed between achieved LDL-C levels and disease progression.

SUMMARY

Addition of evolocumab to statin therapy produces incremental regression of plaque regression in patients with established coronary artery disease. This finding provides a biological rationale for the reported beneficial effects of evolocumab on cardiovascular events.

Dyslipidaemia in nephrotic syndrome: mechanisms and treatment

Nephrotic syndrome is a highly prevalent disease that is associated with high morbidity despite notable advances in its treatment. Many of the complications of nephrotic syndrome, including the increased risk of atherosclerosis and thromboembolism, can be linked to dysregulated lipid metabolism and dyslipidaemia. These abnormalities include elevated plasma levels of cholesterol, triglycerides and the apolipoprotein B-containing lipoproteins VLDL and IDL; decreased lipoprotein lipase activity in the endothelium, muscle and adipose tissues; decreased hepatic lipase activity; and increased levels of the enzyme PCSK9. In addition, there is an increase in the plasma levels of immature HDL particles and reduced cholesterol efflux. Studies from the past few years have markedly improved our understanding of the molecular pathogenesis of nephrotic syndrome-associated dyslipidaemia, and also heightened our awareness of the associated exacerbated risks of cardiovascular complications, progressive kidney disease and thromboembolism. Despite the absence of clear guidelines regarding treatment, various strategies are being increasingly utilized, including statins, bile acid sequestrants, fibrates, nicotinic acid and ezetimibe, as well as lipid apheresis, which seem to also induce partial or complete clinical remission of nephrotic syndrome in a substantial percentage of patients. Future potential treatments will likely also include inhibition of PCSK9 using recently-developed anti-PCSK9 monoclonal antibodies and small inhibitory RNAs, as well as targeting newly identified molecular regulators of lipid metabolism that are dysregulated in nephrotic syndrome.