Proprotein convertase subtilisin/Kexin type-9 (PCSK-9) inhibitors induced liver injury - a retrospective analysis

A promising therapy for fatty liver disease: PCSK9 inhibitors

BACKGROUND

Fatty liver disease (FLD) poses a significant global health concern worldwide, with its classification into nonalcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (AFLD) contingent upon the presence or absence of chronic and excessive alcohol consumption. The absence of specific therapeutic interventions tailored to FLD at various stages of the disease renders its treatment exceptionally arduous. Despite the fact that FLD and hyperlipidemia are intimately associated, there is still debate over how lipid-lowering medications affect FLD. Proprotein Convertase Subtilisin/ Kexin type 9 (PCSK9) is a serine protease predominantly synthesized in the liver, which has a crucial impact on cholesterol homeostasis. Research has confirmed that PCSK9 inhibitors have prominent lipid-lowering properties and substantial clinical effectiveness, thereby justifying the need for additional exploration of their potential role in FLD.

PURPOSE

Through a comprehensive literature search, this review is to identify the relationship and related mechanisms between PCSK9, lipid metabolism and FLD. Additionally, it will assess the pharmacological mechanism and applicability of PCSK9 inhibitors (including naturally occurring PCSK9 inhibitors, such as conventional herbal medicines) for the treatment of FLD and serve as a guide for updating the treatment protocol for such conditions.

METHODS

A comprehensive literature search was conducted using several electronic databases, including Pubmed, Medline, Embase, CNKI, Wanfang database and ClinicalTrials.gov, from the inception of the database to 30 Jan 2024. Key words used in the literature search were "fatty liver", "hepatic steatosis", "PCSK9", "traditional Chinese medicine", "herb medicine", "botanical medicine", "clinical trial", "vivo", "vitro", linked with AND/OR. Most of the included studies were within five years.

RESULTS

PCSK9 participates in the regulation of circulating lipids via both LDLR dependent and independent pathways, and there is a potential association with de novo lipogenesis. Major clinical studies have demonstrated a positive correlation between circulating PCSK9 levels and the severity of NAFLD, with elevated levels of circulating PCSK9 observed in individuals exposed to chronic alcohol. Numerous studies have demonstrated the potential of PCSK9 inhibitors to ameliorate non-alcoholic steatohepatitis (NASH), potentially completely alleviate liver steatosis, and diminish liver impairment. In animal experiments, PCSK9 inhibitors have exhibited efficacy in alleviating alcoholic induced liver lipid accumulation and hepatitis. Traditional Chinese medicine such as berberine, curcumin, resveratrol, piceatannol, sauchinone, lupin, quercetin, salidroside, ginkgolide, tanshinone, lunasin, Capsella bursa-pastoris, gypenosides, and Morus alba leaves are the main natural PCS9 inhibitors. Excitingly, by inhibiting transcription, reducing secretion, direct targeting and other pathways, traditional Chinese medicine exert inhibitory effects on PCSK9, thereby exerting potential FLD therapeutic effects.

CONCLUSION

PCSK9 plays an important role in the development of FLD, and PCSK9 inhibitors have demonstrated beneficial effects on lipid regulation and FLD in both preclinical and clinical studies. In addition, some traditional Chinese medicines have improved the disease progression of FLD by inhibiting PCSK9 and anti-inflammatory and antioxidant effects. Consequently, the inhibition of PCSK9 appears to be a promising therapeutic strategy for FLD.

PCSK9-D374Y Suppresses Hepatocyte Migration through Downregulating Free Cholesterol Efflux Rate and Activity of Extracellular Signal-Regulated Kinase

Proprotein convertase subtilisin/kexin type 9 can mediate the intracellular lysosomal degradation of the low-density lipoprotein receptor protein in hepatocytes and decrease the liver's ability to scavenge low-density lipoprotein cholesterol from circulation, resulting in high levels of cholesterol in the circulatory system. Current studies have primarily focused on the relationship between PCSK9 and blood lipid metabolism; however, the biological function of PCSK9 in hepatocytes is rarely addressed. In this study, we evaluate its effects in the human hepatoma carcinoma cell line HepG2, including proliferation, migration, and free cholesterol transport. PCSK9-D374Y is a gain-of-function mutation that does not affect proliferation but significantly suppresses the migration and cholesterol efflux capacity of these cells. The suppression of the transmembrane outflow of intracellular-free cholesterol regulates small G proteins and the suppression of extracellular signal-regulated kinase. In summary, PCSK9-D374Y affects hepatocyte features, including their migration and free cholesterol transport capabilities.

PCSK9 Inhibitor: Safe Alternative to Fill the Treatment Gap in Statin-Limited Conditions?

Lipid-lowering therapy is of great importance in reducing the burden of atherosclerotic cardiovascular disease. Statins act as first-line therapy in the current lipid management guidelines. However, statin use is limited in (1) statin-induced adverse events, including statin-associated muscle symptoms, new-onset diabetes mellitus, drug-induced liver injuries, acute kidney injuries, cognitive effects, hemorrhagic strokes, and cataracts; (2) special populations, including pregnant and lactating patients, patients with decompensated cirrhosis, and patients on dialysis; (3) coadministration with statin-interactive drugs, such as anti-human immunodeficiency virus drugs, anti-hepatitis C virus drugs, and immunosuppressive drugs. These considerable statin-limited groups are in urgent need of safer alternative lipid-lowering options. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are attracting widespread attention for their documented safety in general populations and superior lipid-lowering properties. Therefore, questions have been raised whether PCSK9 inhibitors could be a safe alternative in patients who are intolerant to statin therapy. In this review, we discuss the safety of PCSK9 inhibitors in statin-limited conditions. We conclude that PCSK9 inhibitors are a safe alternative lipid-lowering therapy in various statin-limited conditions. Furthermore, we identify several limitations in the current literature and suggest future directions, for the refinement of lipid management regimens.

Sex difference in circulating PCSK9 and its clinical implications

Proprotein convertase subtilisin kexin type 9 (PCSK9) is a proprotein convertase that increases plasma low-density lipoprotein cholesterol (LDL-C) levels by triggering the degradation of LDL receptors (LDLRs). Beyond the regulation of circulating LDL-C, PCSK9 also has direct atherosclerotic effects on the vascular wall and is associated with coronary plaque inflammation. Interestingly, emerging data show that women have higher circulating PCSK9 concentrations than men, suggesting that the potential roles of PCSK9 may have different impacts according to sex. In this review, we summarize the studies concerning sex difference in circulating levels of PCSK9. In addition, we report on the sex differences in the relations of elevated circulating PCSK9 levels to the severity and prognosis of coronary artery disease, the incidence of type 2 diabetes mellitus, and neurological damage after cardiac arrest and liver injury, as well as inflammatory biomarkers and high-density lipoprotein cholesterol (HDL-C). Moreover, sex difference in the clinical efficacy of PCSK9 inhibitors application are reviewed. Finally, the underlying mechanisms of sex difference in circulating PCSK9 concentrations and the clinical implications are also discussed.

Effects of PCSK-9 Inhibition by Alirocumab Treatments on Biliary Cirrhotic Rats

Hyperlipidemia and oxidative stress with elevated oxidized low-density lipoprotein (ox-LDL) exacerbate hepatic inflammation and fibrosis. The plasma level of low-density lipoprotein (LDL) is controlled by proprotein convertase subtilisin/kexin 9 (PCSK9). Alirocumab is a monoclonal antibody that decreases LDL via inhibiting PCSK9 function. Apart from lipid-lowering effects, alirocumab exerts anti-inflammation, anti-angiogenesis and anti-oxidant effects. This study aims to investigate the impact of alirocumab treatment on common bile duct ligation (BDL)-induced biliary cirrhotic rats. After a 4-week treatment of alirocumab, the hemodynamic data, blood biochemistry, ox-LDL level, oxidative stress markers, severity of hepatic encephalopathy and abnormal angiogenesis of BDL rats were measured and compared to the control group. BDL rats presented cirrhotic pictures and elevated ammonia, total cholesterol, LDL and ox-LDL levels compared to the control group. Alirocumab decreased plasma levels of total cholesterol, LDL, and oxidative stress markers; however, it did not affect the hemodynamics, liver and renal biochemistry, and the plasma levels of ammonia and ox-LDL. The motor activities, portal-systemic collaterals and mesenteric vascular density were not significantly different between alirocumab-treated and control groups. In addition, it did not affect hepatic inflammation, intrahepatic angiogenesis, liver fibrosis and free cholesterol accumulation in the liver of BDL rats. In conclusion, PCSK9 inhibition by alirocumab treatment ameliorates hyperlipidemia and systemic oxidative stress in biliary cirrhotic rats. However, it does not affect the plasma level of ox-LDL, intrahepatic inflammation and fibrosis. In addition, PCSK9 inhibition has a neutral effect on abnormal angiogenesis and hepatic encephalopathy in biliary cirrhotic rats.

Effects of proprotein convertase subtilisin/kexin type-9 inhibitors on fatty liver

BACKGROUND

Many studies have investigated the progression of nonalcoholic fatty liver disease (NAFLD) and its predisposing risk factors, but the conclusions from these studies have been conflicting. More challenging is the fact that no effective treatment is currently available for NAFLD.

AIM

To determine the effects of proprotein convertase subtilisin/kexin type-9 (PCSK9) inhibitors on fatty infiltration of the liver.

METHODS

This retrospective, chart review-based study was conducted on patients, 18-year-old and above, who were currently on PCSK9 inhibitor drug therapy. Patients were excluded from the study according to missing pre- or post-treatment imaging or laboratory values, presence of cirrhosis or rhabdomyolysis, or development of acute liver injury during the PCSK9 inhibitor treatment period; the latter being due to false elevation of liver function markers, alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Radiographic improvement was assessed by a single radiologist, who read both the pre- and post-treatment images to minimize reading bias. Fatty infiltration of the liver was also assessed by changes in ALT and AST, with pre- and post-treatment levels compared by paired t-test (alpha criterion: 0.05).

RESULTS

Of the 29 patients included in the study, 8 were male (27.6%) and 21 were female (72.4%). Essential hypertension was present in 25 (86.2%) of the patients, diabetes mellitus in 18 (62.1%) and obesity in 15 (51.7%). In all, patients were on PCSK9 inhibitors for a mean duration of 23.69 ± 11.18 mo until the most recent ALT and AST measures were obtained. Of the 11 patients who received the radiologic diagnosis of hepatic steatosis, 8 (72.73%) achieved complete radiologic resolution upon use of PCSK9 inhibitors (mean duration of 17.6 mo). On average, the ALT level (IU/L) decreased from 21.83 ± 11.89 at pretreatment to 17.69 ± 8.00 at post-treatment (2-tailed P = 0.042) and AST level (IU/L) decreased from 22.48 ± 9.00 pretreatment to 20.59 ± 5.47 post-treatment (2-tailed P = 0.201).

CONCLUSION

PCSK9 inhibitors can slow down or even completely resolve NAFLD.

Pathophysiology and pharmacological management of pulmonary and cardiovascular features of COVID-19

The first confirmed case of novel Coronavirus Disease 2019 (COVID-19) in the United States was reported on January 20, 2020. As of November 24, 2020, close to 12.2 million cases of COVID-19 was confirmed in the US, with over 255,958 deaths. The rapid transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), its unusual and divergent presentation has strengthened the status of COVID-19 as a major public health threat. In this review, we aim to 1- discuss the epidemiological data from various COVID-19 patient cohorts around the world and the USA as well the associated risk factors; 2- summarize the pathophysiology of SARS-CoV-2 infection and the underlying molecular mechanisms for the respiratory and cardiovascular manifestations; 3- highlight the potential treatments and vaccines as well as current clinical trials for COVID-19.