Association of Serum PCSK9 Levels with Antibiotic Resistance and Severity of Disease in Patients with Bacterial Infections Admitted to Intensive Care Units

The role of natural products as PCSK9 modulators: A review

A variety of mechanisms and drugs have been shown to attenuate cardiovascular disease (CVD) onset and/or progression. Recent researchers have identified a potential role of proprotein convertase subtilisin/kexin type 9 (PCSK9) in modulating lipid metabolism and reducing plasma low density lipoprotein (LDL) levels. PCSK9 is the central protein in the metabolism of LDL cholesterol (LDL-C) owing to its major function in LDL receptor (LDLR) degradation. Due to the close correlation of cardiovascular disease with lipid levels, many in vivo and in vitro investigations are currently underway studying the physiological role of PCSK9. Furthermore, many studies are actively investigating the mechanisms of various compounds that influence lipid associated-disorders and their associated cardiovascular diseases. PCSK9 inhibitors have been shown to have significant impact in the prevention of emerging cardiovascular diseases. Natural products can effectively be used as PCSK9 inhibitors to control lipid levels through various mechanisms. In this review, we evaluate the role of phytochemicals and natural products in the regulation of PCSK9, and their ability to prevent cardiovascular diseases. Moreover, we describe their mechanisms of action, which have not to date been delineated.

Plasma Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) as a Possible Biomarker for Severe COVID-19

Proprotein convertase subtilisin/kexin type 9 (PCSK9) reduces low density lipoprotein (LDL) uptake, leading to increased plasma levels of LDL. In addition, PCSK9 has been implicated in inflammation independently of the effects on cholesterol metabolism. The current analysis showed that our 156 patients with systemic inflammatory response syndrome (SIRS) or sepsis had higher plasma PCSK9 levels in contrast with the 68 healthy controls. COVID-19 sepsis patients had increased plasma PCSK9 levels in comparison to sepsis patients not infected by SARS-CoV-2. For further analysis, patients were divided in two groups based on COVID-19. In both sub-cohorts, plasma PCSK9 levels did not correlate with C-reactive protein, leukocyte count, and procalcitonin. Plasma PCSK9 levels of both patient groups did not significantly differ among SIRS/sepsis patients with and without dialysis and patients with and without ventilation. Furthermore, vasopressor therapy was not significantly associated with altered plasma PCSK9 levels. In the non-COVID-19 SIRS/sepsis group, patients with Gram-negative and Gram-positive infections had similar plasma PCSK9 levels as patients without a detectable pathogen in their blood. In conclusion, the current study suggests PCSK9 as a possible biomarker for COVID-19, but this needs to be validated in larger cohorts.

Preclinical toxicity assessment of a peptide-based antiPCSK9 vaccine in healthy mice

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition is a novel cholesterol-lowering treatment for decreasing the risk of atherosclerosis. We have previously shown that active immunization using the antiPCSK9 vaccine could decrease hypercholesterolemia and impede the development of atherosclerotic lesions in the experimental model of atherosclerosis. Here, we evaluated the toxicity of the vaccine in healthy mice.

METHODS

Forty male and female albino mice were divided into 4 experimental groups, including vaccine female (10 mice) and male (10 mice) groups receiving the antiPCSK9 vaccine as well as the corresponding control female (10 mice) and male (10 mice) groups receiving the phosphate buffer. Vaccination was planned based on 4 subcutaneous injections of the vaccine formulation (10 µg/mouse) in bi-weekly intervals. The toxicity study was performed by the subacute protocol, 28 days after the last vaccine injection. To this end, the plasma levels of lipid indexes, urea, creatinine, AST, ALT, ALP, and fasting plasma glucose (FPG), as well as the CBC test were measured. To evaluate histopathological alterations, various tissues including the heart, liver, kidney, spleen, and brain were studied using hematoxylin & eosin (H&E) staining by an expert pathologist. The severity of damage to the tissue was considered based on the standard classification; grade 1 as light damage, grade 2 as moderate damage, grade 3 as near intense damage, and grade 4 as intense damage.

RESULTS

The results showed non-significant changes of total cholesterol, LDL-C, triglyceride, HDL-C, FBS, creatinine, urea, AST, ALP, ALT, and PAB in the vaccinated mice when compared with control mice. The CBS test indicated that there were no significant changes in the levels of WBC, RBC, HGB, HCT, MCH, MCHC, PLT, LYM, NEUT, MCV, RDW-S, PDW, and MPV in the vaccinated mice when compared with control mice. Evaluating histopathological alterations in various tissues indicated no significant adverse effects in vaccinated mice when compared to control mice.

CONCLUSION

The findings of the present study indicate that antiPCSK9 is safe and exerts no adverse effects on the function of different organs and blood levels of cellular and biochemical biomarkers in healthy mice.

The effect of PCSK9 immunization on the hepatic level of microRNAs associated with the PCSK9/LDLR pathway

INTRODUCTION

MicroRNAs (miRNAs) are a class of gene expression epigenetic regulators that play roles in regulating genes involved in cholesterol homeostasis, including low-density lipoprotein receptor (LDLR) and PCSK9; therefore, miRNAs have been suggested as potential therapeutic targets for treating cardiometabolic disorders. Thus, the present study aimed to assess the effect of immunotherapy with the PCSK9 peptide vaccine on the hepatic expression levels of microRNAs associated with the LDLR pathway, including miRNA-27a, miRNA-30c, and miRNA-191, in normal vaccinated mice.

MATERIAL AND METHODS

PCSK9 immunogenic peptide and 0.4% alum adjuvant were mixed at a 1 : 1 ratio and used as a vaccine formulation. Male albino mice were randomly assigned to the vaccine or control group. Mice in the vaccine group were injected four times at two-week intervals with a PCSK9 peptide vaccine, and mice in the control group were injected with phosphate-buffered saline (PBS). Animal livers were sampled 2 weeks after the last injection to assess miRNA expression levels. The hepatic expression levels of miRNA-27a, miRNA-30c, and miRNA-191 were evaluated by SYBR Green real-time PCR, quantified by a comparative (2^{- Δ Δ CT}) method (fold change (FC)) and normalized to U6 small nuclear RNA (U6snRNA) expression as an internal control.

RESULTS

The hepatic expression level of miRNA-27a was significantly lower in mice following immunotherapy with the PCSK9 peptide vaccine compared to the control group (FC: 0.731 ±0.1, p = 0.027). Also, there was a borderline significantly lower hepatic expression level of miRNA-30c in the vaccinated group compared to the control (FC: 0.569 ±0.1, p = 0.078). However, no significant differences were found in the hepatic expression level of miRNA-191 between the two studied groups (FC: 0.852 ±0.1, p = 0.343).

CONCLUSIONS

According to the findings, the PCSK9 peptide vaccine could effectively reduce the hepatic expression level of miRNA-27a and may be helpful in the management of LDL-C level and atherosclerosis, which may be mediated through the LDLR pathway.

Plasma Proprotein Convertase Subtilisin/kexin Type 9 (PCSK9) in the Acute Respiratory Distress Syndrome

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that is a mediator of the immune response to sepsis. PCSK9 is also highly expressed in pneumocytes and pulmonary endothelial cells. We hypothesized that serum PCSK9 levels would be associated with death and ICU outcomes in patients with ARDS.

Methods

Using data and plasma samples from the NIH BioLINCC data repository, we assembled a cohort of 1,577 patients with the acute respiratory distress syndrome (ARDS) enrolled in two previously completed clinical trials, EDEN and SAILS. We measured PCSK9 levels in plasma within 24 h of intubation using commercially available ELISA kits (R&D Systems). We assessed the association of PCSK9 with mortality using Cox proportional hazard models. We also assessed clinical factors associated with PCSK9 level and the association of PCSK9 with the number of days free of mechanical ventilation and days free of ICU care.

Results

In 1,577 ARDS patients, median age was 53 years (IQR 42–65 years) and median APACHE III score 91 (72–111) connoting moderate critical illness. PCSK9 levels were 339.3 ng/mL (IQR 248.0–481.0). In multivariable models, race, cause of ARDS, body mass index, pre-existing liver disease, body temperature, sodium, white blood cell count and platelet count were associated with PCSK9 level. Presence of sepsis, use of vasopressors and ventilator parameters were not associated with PCSK9 level. PCSK9 levels were not associated with in-hospital mortality (HR per IQR 0.96, 95% CI 0.84–1.08, P = 0.47). Higher PCSK9 levels were associated with fewer ICU and ventilator free days.

Conclusions

Plasma PCSK9 is not associated with mortality in ARDS, however higher PCSK9 levels are associated with secondary outcomes of fewer ICU free and ventilator free days. Clinical factors associated with PCSK9 in ARDS are largely unmodifiable. Further research to define the mechanism of this association is warranted.

The role of PCSK9 in infectious diseases

BACKGROUND

In recent years, many aspects of the physiological role of PCSK9 have been elucidated, particularly regarding its role in lipid metabolism, cardiovascular risk, and its role in innate immunity. Increasing evidence is available about the involvement of PCSK9 in the pathogenesis of viral infections, mainly HCV, and the regulation of host response to bacterial infections, primarily sepsis and septic shock. Moreover, the action of PCSK9 has been investigated as a crucial step in the pathogenesis of malaria infection and disease severity.

OBJECTIVE

This paper aims to review the available published literature on the role of PCSK9 in a wide array of infectious diseases.

CONCLUSION

Besides the ongoing investigation on PCSK9 inhibition among HIV-infected patients to treat HIV- and ART-related hyperlipidemia, preclinical studies indicate how PCSK9 is involved in reducing the replication of HCV. Interestingly, high plasmatic PCSK9 levels have been described in patients with sepsis. Moreover, a protective role of PCSK9 inhibition has also been proposed against dengue and SARS-CoV-2 viral infections. Finally, a loss of function in the PCSK9-encoding gene has been reported to reduce malaria infection mortality.

PCSK9: A Potential Therapeutic Target for Sepsis

Sepsis is a life-threatening organ dysfunction syndrome caused by a dysregulated host response to infection. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is often upregulated in the presence of sepsis and infectious diseases. In sepsis, PCSK9 degraded the low-density lipoprotein cholesterol (LDL) receptors (LDL-R) of the hepatocytes and the very low-density lipoprotein cholesterol receptors (VLDL-R) of the adipocytes, which then subsequently reduced pathogenic lipid uptake and clearance/sequestration. Moreover, it might improve cholesterol accumulation and augment toll-like receptor function in macrophages, which supported inflammatory responses. Accordingly, PCSK9 might show detrimental effects on immune host response and survival in sepsis. However, the exact roles of PCSK9 in the pathogenesis of sepsis are still not well defined. In this review, we summarized the literatures focusing on the roles of PCSK9 in sepsis. Our review provided an additional insight in the role of PCSK9 in sepsis, which might serve as a potential target for the treatment of sepsis.

An update on PCSK9 inhibitors- pharmacokinetics, drug interactions, and toxicity

INTRODUCTION

While atherosclerotic cardiovascular disease is affecting growing numbers of patients, lipid-lowering therapies have been continuously improving to achieve prevention of cardiovascular events. Thus, the appearance of a novel therapeutic class, PCSK9 inhibitors, has raised both high expectations as well as concern over possible adverse effects.

AREAS COVERED

This current review aims to analyze adverse events of special interest linked to PCSK9 inhibitors and give recommendations regarding further conduct when dealing with patients on this therapy. The most stringent adverse effect, neurocognitive impairment has been investigated in several studies, concluding that PCSK9 inhibitors neither improved nor worsened cognitive function. While new onset diabetes mellitus has also been a cause of concern due to its possible association with lipid lowering therapies, studies conducted so far have dispelled this possibility by showing that PCSK9 inhibitors do not increase this risk. Also, statin-associated muscle symptoms have not been proven to arise after the use of PCSK9 inhibitors, even in statin-intolerant patients.

EXPERT OPINION

In conclusion, it can be safely stated that so far, no compelling evidence links PCSK9 inhibitors to these adverse events; however, long-term trials are always welcome to further assess potential adverse effects.