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.

The Immunogenic Potential of PCSK9 Peptide Vaccine in Mice.

AIM: To evaluate the immunogenic potential of the carrier-free peptide-based anti-PCSK9 (proprotein convertase subtilisin/kexin 9) vaccine in albino mice. METHODS: The immunogenic pcsk9 peptide and 0.4% alum adjuvant were mixed thoroughly at a 1:1 ratio and used as a vaccine formulation. To assess the humoral immune response, animals' blood was sampled two weeks after the last immunization. The ELISA method was employed to measure serum anti-PCSK9 antibody titers, PCSK9 concentrations, and PCSK9/LDLR interaction. RESULTS: ELISA analysis showed significant induction of IgG antibody titers by PCSK9 peptide vaccine in vaccinated mice sera compared to the control mice (in male and female mice were 12000±586 and 11566±642, respectively, p<0.001). Mechanistic analyses showed a significant reduction in serum PCSK9 concentrations by vaccine-induced antibodies in vaccine groups compared to the control groups (in male mice by 29±5 ng/mL (22.4%), p<0.001 and female mice by 26±5 ng / mL (21.0%), p<0.001). Serum concentrations of PCSK9 in control and vaccine groups were 131±8.6 ng / mL and 102±8.1 ng/ml in male mice and 124±6 ng/ml and 98±10 ng/ml in female mice, respectively. Moreover, vaccine-induced antibodies inhibited the PCSK9-LDLR interaction in male and female groups by 34% and 26%, respectively. No significant difference was detected between the male and female groups in all tests (p>0.05). CONCLUSION: According to our results, the PCSK9 peptide vaccine provoked the humoral immune system in albino mice to produce functional antibodies that inhibit plasma PCSK9. These effects were seen in both genders without any significant difference.

Berberine: Ins and outs of a nature-made PCSK9 inhibitor.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein and a critical regulator of low-density lipoprotein-cholesterol (LDL-C) through inducing degradation of the LDL receptor (LDLR) within the hepatocyte lysosome. PCSK9 deficiency significantly improves the survival rate of cardiovascular disease (CVDs) patients. Up to now, various PCSK9 inhibition approaches have been tested. However, the currently available PCSK9 inhibitors' widespread use is limited due to their inconvenient method of administration and high cost. On the other hand, inhibiting PCSK9 with nutraceuticals is safe and affordable. The plant-derived compound berberine has shown anti-PCSK9 activity in several studies. Berberine is an isoquinoline quaternary alkaloid of phyto origin. Berberine treatment boosts the hepatic expression of LDLRs, while decreasing the expression and secretion of the LDLR modulator PCSK9. The current review presents a collection of in vitro and in vivo studies investigating berberine's effects on PCSK9 mRNA expression, protein level, and function.