Structural studies offer a framework for understanding the role of properdin in the alternative pathway and beyond.

Structures of alternative pathway proteins have offered a comprehensive structural basis for understanding the molecular mechanisms governing activation and regulation of the amplification pathway of the complement cascade. Although properdin (FP) is required in vivo to sustain a functional alternative pathway, structural studies have been lagging behind due to the extended structure and polydisperse nature of FP. We review recent progress with respect to structure determination of FP and its proconvertase/convertase complexes. These structures identify in detail regions in C3b, factor B and FP involved in their mutual interactions. Structures of FP oligomers obtained by integrative studies have shed light on how FP activity depends on its oligomerization state. The accumulated structural knowledge allows us to rationalize the effect of point mutations causing FP deficiency. The structural basis for FP inhibition by the tick CirpA proteins is reviewed and the potential of alphafold2 predictions for understanding the interaction of FP with other tick proteins and the NKp46 receptor on host immune cells is discussed. The accumulated structural knowledge forms a comprehensive basis for understanding molecular interactions involving FP, pathological conditions arising from low levels of FP, and the molecular strategies used by ticks to suppress the alternative pathway.

Convertase-dependent regulation of membrane-tethered and secreted ligands tunes dendrite adhesion.

During neural development, cellular adhesion is crucial for interactions among and between neurons and surrounding tissues. This function is mediated by conserved cell adhesion molecules, which are tightly regulated to allow for coordinated neuronal outgrowth. Here, we show that the proprotein convertase KPC-1 (homolog of mammalian furin) regulates the Menorin adhesion complex during development of PVD dendritic arbors in Caenorhabditis elegans. We found a finely regulated antagonistic balance between PVD-expressed KPC-1 and the epidermally expressed putative cell adhesion molecule MNR-1 (Menorin). Genetically, partial loss of mnr-1 suppressed partial loss of kpc-1, and both loss of kpc-1 and transgenic overexpression of mnr-1 resulted in indistinguishable phenotypes in PVD dendrites. This balance regulated cell-surface localization of the DMA-1 leucine-rich transmembrane receptor in PVD neurons. Lastly, kpc-1 mutants showed increased amounts of MNR-1 and decreased amounts of muscle-derived LECT-2 (Chondromodulin II), which is also part of the Menorin adhesion complex. These observations suggest that KPC-1 in PVD neurons directly or indirectly controls the abundance of proteins of the Menorin adhesion complex from adjacent tissues, thereby providing negative feedback from the dendrite to the instructive cues of surrounding tissues.

Complement component C3: A structural perspective and potential therapeutic implications.

As the most abundant component of the complement system, C3 and its proteolytic derivatives serve essential roles in the function of all three complement pathways. Central to this is a network of protein-protein interactions made possible by the sequential proteolysis and far-reaching structural changes that accompany C3 activation. Beginning with the crystal structures of C3, C3b, and C3c nearly twenty years ago, the physical transformations underlying C3 function that had long been suspected were finally revealed. In the years that followed, a compendium of crystallographic information on C3 derivatives bound to various enzymes, regulators, receptors, and inhibitors generated new levels of insight into the structure and function of the C3 molecule. This Review provides a concise classification, summary, and interpretation of the more than 50 unique crystal structure determinations for human C3. It also highlights other salient features of C3 structure that were made possible through solution-based methods, including Hydrogen/Deuterium Exchange and Small Angle X-ray Scattering. At this pivotal time when the first C3-targeted therapeutics begin to see use in the clinic, some perspectives are also offered on how this continually growing body of structural information might be leveraged for future development of next-generation C3 inhibitors.

Complement C3-targeted therapy in C3 glomerulopathy, a prototype of complement-mediated kidney diseases.

C3 glomerulopathy (C3G) is a rare and complex kidney disease that primarily affects young adults. Renal outcomes remain poor in the absence of specific treatment. C3G is driven by uncontrolled overactivation of the alternative complement pathway, which is mainly of acquired origin. Functional characterization of complement abnormalities (i.e., autoantibodies targeting complement components and variants in complement genes) identified in patients and experimental models of the disease improved the understanding of the disease, making C3G a prototype of complement-mediated diseases. The contribution of C3 convertase, as well as C5 convertase, in disease occurrence, phenotype, and severity is now well established, offering various potential therapeutic interventions. However, the lack of sufficient efficiency in anti-C5 therapy highlights the extreme complexity of the disease and the need for new therapeutic approaches based on C3 and C3 convertase axis inhibition. Here, we provide an overview of the complement activation mechanism involved in C3G and discuss therapeutic options based on complement inhibitors, with a specific focus on C3 inhibition.

Established and Emerging Nucleic Acid Therapies for Familial Hypercholesterolemia.

Familial hypercholesterolemia (FH) is a genetic disease that leads to elevated low-density lipoprotein cholesterol levels and risk of coronary heart disease. Current therapeutic options for FH remain relatively limited and only partially effective in both lowering low-density lipoprotein cholesterol and modifying coronary heart disease risk. The unique characteristics of nucleic acid therapies to target the underlying cause of the disease can offer solutions unachievable with conventional medications. DNA- and RNA-based therapeutics have the potential to transform the care of patients with FH. Recent advances are overcoming obstacles to clinical translation of nucleic acid-based medications, including greater stability of the formulations as well as site-specific delivery, making gene-based therapy for FH an alternative approach for treatment of FH.

Ablation of specific insulin-like growth factor I forms reveals the importance of cleavage for regenerative capacity and glycosylation for skeletal muscle storage.

Insulin-like growth factor-I (IGF-I) facilitates mitotic and anabolic actions in all tissues. In skeletal muscle, IGF-I can promote growth and resolution of damage by promoting satellite cell proliferation and differentiation, suppressing inflammation, and enhancing fiber formation. While the most well-characterized form of IGF-I is the mature protein, alternative splicing and post-translational modification complexity lead to several additional forms of IGF-I. Previous studies showed muscle efficiently stores glycosylated pro-IGF-I. However, non-glycosylated forms display more efficient IGF-I receptor activation in vitro, suggesting that the removal of the glycosylated C terminus is a necessary step to enable increased activity. We employed CRISPR-Cas9 gene editing to ablate IGF-I glycosylation sites (2ND) or its cleavage site (3RA) in mice to determine the necessity of glycosylation or cleavage for IGF-I function in postnatal growth and during muscle regeneration. 3RA mice had the highest circulating and muscle IGF-I content, whereas 2ND mice had the lowest levels compared to wild-type mice. After weaning, 4-week-old 2ND mice exhibited higher body and skeletal muscle mass than other strains. However, by 16 weeks of age, muscle and body size differences disappeared. Even though 3RA mice had more IGF-I stored in muscle in homeostatic conditions, regeneration was delayed after cardiotoxin-induced injury, with prolonged necrosis most evident at 5 days post injury (dpi). In contrast, 2ND displayed improved regeneration with reduced necrosis, and greater fiber size and muscle mass at 11 and 21 dpi. Overall, these results demonstrate that while IGF-I glycosylation may be important for storage, cleavage is needed to enable IGF-I to be used for efficient activity in postnatal growth and following acute injury.

PCSK9 dysregulates cholesterol homeostasis and triglyceride metabolism in olanzapine-induced hepatic steatosis via both receptor-dependent and receptor-independent pathways.

Schizophrenia, affecting approximately 1% of the global population, is often treated with olanzapine. Despite its efficacy, olanzapine's prolonged use has been associated with an increased risk of cardiovascular diseases and nonalcoholic fatty liver disease (NAFLD); however, the underlying mechanism remains unclear. Proprotein convertase subtilisin kexin type 9 (PCSK9) plays a crucial role in lipid metabolism and is involved in NAFLD pathogenesis via an unknown mechanism. This study aims to investigate the role of PCSK9 in olanzapine-induced NAFLD. C57BL/6J mice and HepG2 and AML12 cell lines were treated with varying concentrations of olanzapine to examine the effects of olanzapine on PCSK9 and lipid metabolism. PCSK9 levels were manipulated using recombinant proteins, plasmids, and small interfering RNAs in vitro, and the effects on hepatic lipid accumulation and gene expression related to lipid metabolism were assessed. Olanzapine treatment significantly increased PCSK9 levels in both animal and cell line models, correlating with elevated lipid accumulation. PCSK9 manipulation demonstrated its central role in mediating hepatic steatosis through both receptor-dependent pathways (impacting NPC1L1) and receptor-independent pathways (affecting lipid synthesis, uptake, and cholesterol biosynthesis). Interestingly, upregulation of SREBP-1c, rather than SREBP-2, was identified as a key driver of PCSK9 increase in olanzapine-induced NAFLD. Our findings establish PCSK9 as a pivotal factor in olanzapine-induced NAFLD, influencing both receptor-related and metabolic pathways. This highlights PCSK9 inhibitors as potential therapeutic agents for managing NAFLD in schizophrenia patients treated with olanzapine.

PCSK9 inhibitors as safer therapeutics for atherosclerotic cardiovascular disease (ASCVD): Pharmacophore design and molecular dynamics analysis.

Cardiovascular disorders are still challenging and are among the deadly diseases. As a major risk factor for atherosclerotic cardiovascular disease, dyslipidemia, and high low-density lipoprotein cholesterol in particular, can be prevented primary and secondary by lipid-lowering medications. Therefore, insights are still needed into designing new drugs with minimal side effects. Proprotein convertase subtilisin/kexin 9 (PCSK9) enzyme catalyses protein-protein interactions with low-density lipoprotein, making it a critical target for designing promising inhibitors compared to statins. Therefore, we screened for potential compounds using a redesigned PCSK9 conformational behaviour to search for a significantly extensive chemical library and investigated the inhibitory mechanisms of the final compounds using integrated computational methods, from ligand essential functional group screening to all-atoms MD simulations and MMGBSA-based binding free energy. The inhibitory mechanisms of the screened compounds compared with the standard inhibitor. K31 and K34 molecules showed stronger interactions for PCSK9, having binding energy (kcal/mol) of -33.39 and -63.51, respectively, against -27.97 of control. The final molecules showed suitable drug-likeness, non-mutagenesis, permeability, and high solubility values. The C-α atoms root mean square deviation and root mean square fluctuation of the bound-PCSK9 complexes showed stable and lower fluctuations compared to apo PCSK9. The findings present a model that unravels the mechanism by which the final molecules proposedly inhibit the PCSK9 function and could further improve the design of novel drugs against cardiovascular diseases.

Granulocyte pro-myeloperoxidase is redundantly processed by proprotein convertase furin and PC7 in HL-60 cells.

Neutrophil myeloperoxidase/H2O2/chloride system is a key mechanism to control pathogen infection. This enzyme, myeloperoxidase, plays a pivotal role in the arsenal of azurophilic granules that are released through degranulation upon neutrophil activation, which trigger local hypochlorous acid production. Myeloperoxidase gene encodes a protein precursor named promyeloperoxidase that arbors a propeptide that gets cleaved later during secretory routing in post-endoplasmic reticulum compartments. Although evidence suggested that this processing event was performed by one or different enzymes from the proprotein convertases family, the identity of this enzyme was never investigated. In this work, the naturally producing myeloperoxidase promyelocytic cell line HL-60 was used to investigate promyeloperoxidase cleavage during granulocytic differentiation in response to proprotein convertase inhibitors decanoyl-RVKR-chloromethylketone and hexa-d-arginine. Stable PC knockdown of endogenously expressed proprotein convertases, furin and PC7, was achieved using lentiviral delivery of shRNAs. None of the knockdown cell line could reproduce the effect of the pan-proprotein convertases inhibitor decanoyl-RVKR-chloromethylketone that accumulated intracellular promyeloperoxidase stores in HL-60 cells, therefore illustrating that both furin and PC7 redundantly process this proprotein.

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.

Genetic backgrounds and diagnosis of familial hypercholesterolemia.

Lipid disorders play a critical role in the intricate development of atherosclerosis and its clinical consequences, such as coronary heart disease and stroke. These disorders are responsible for a significant number of deaths in many adult populations worldwide. Familial hypercholesterolemia (FH) is a genetic disorder that causes extremely high levels of LDL cholesterol. The most common mutations occur in genes responsible for low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), or proprotein convertase subtilisin/kexin type 9 (PCSK9). While genetic testing is a dependable method for diagnosing the disease, it may not detect primary mutations in 20%-40% of FH cases.

Review of Evolocumab for the Reduction of LDL Cholesterol and Secondary Prevention of Atherosclerotic Cardiovascular Disease.

Elevated low-density lipoprotein cholesterol (LDL-C) is a major causal factor for atherosclerotic cardiovascular disease (ASCVD), the leading cause of mortality worldwide. Statins are the recommended first-line lipid-lowering therapy (LLT) for patients with primary hypercholesterolemia and established ASCVD, with LLT intensification recommended in the substantial proportion of patients who do not achieve levels below guideline-recommended LDL-C thresholds with statin treatment alone. The proprotein convertase subtilisin/kexin type 9 inhibitor monoclonal antibody evolocumab has demonstrated significant LDL-C reductions of > 60% in the clinical trial and open-label extension settings, with LDL-C reductions observed early post-evolocumab initiation and maintained long term, during up to 8.4 years of follow-up. Evolocumab therapy, when added to a statin, also conferred a significant reduction in major cardiovascular (CV) events, including a 20% reduction in the composite of CV death, myocardial infarction (MI), or stroke. The absolute benefits were enhanced among various patient types at high and very high risk for secondary ASCVD (e.g., with recent MI, multiple events or peripheral artery disease). Importantly, evolocumab treatment resulted in incremental CV risk reductions during the extended follow-up, including a 23% reduction in CV mortality and no apparent LDL-C level below which there is no further CV risk reduction. Hence, the evolocumab clinical data support the need for early and significant LDL-C lowering, especially in vulnerable ASCVD patients, in order to derive the greatest benefit in the long term. Importantly, evolocumab had no impact on any treatment emergent adverse events apart from a small increase in local injection site reactions. A growing body of real-world evidence (RWE) for evolocumab in heterogeneous populations is consistent with the trial data, including robust LDL-C reductions below guideline-recommended thresholds, a favourable safety profile even at the lowest levels of LDL-C achieved, and a high treatment persistence rate of > 90%. Altogether, this review highlights findings from 50 clinical trials and RWE studies in > 51,000 patients treated with evolocumab, to demonstrate the potential of evolocumab to address the healthcare gap in LDL-C reduction and secondary prevention of ASCVD in a variety of high- and very high-risk patients.

Association of lipid-lowering drug targets with risk of cutaneous melanoma: a mendelian randomization study.

BACKGROUND: Melanoma proliferation is partly attributed to dysregulated lipid metabolism. The effectiveness of lipid-lowering drugs in combating cutaneous melanoma (CM) is a subject of ongoing debate in both in vitro and clinical studies. METHOD: This study aims to evaluate the causal relationship between various lipid-lowering drug targets, namely 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR, targeted by statins), Proprotein convertase subtilisin/kexin type 9 (PCSK9, targeted by alirocumab and evolocumab), and Niemann-Pick C1-like 1 (NPC1L1, targeted by ezetimibe), and the outcomes of cutaneous melanoma. To mimic the effects of lipid-lowering drugs, we utilized two genetic tools: analysis of polymorphisms affecting the expression levels of drug target genes, and genetic variations linked to low-density lipoprotein cholesterol levels and drug target genes. These variations were sourced from genome-wide association studies (GWAS). We applied Summary-data-based Mendelian Randomization (SMR) and Inverse Variance Weighted Mendelian Randomization (IVW-MR) to gauge the effectiveness of these drugs. RESULTS: Our findings, with SMR results showing an odds ratio (OR) of 1.44 (95% CI: 1.08-1.92; P = 0.011) and IVW-MR results indicating an OR of 1.56 (95% CI: 1.10-2.23; P = 0.013), demonstrate a positive correlation between PCSK9 expression and increased risk of CM. However, no such correlations were observed in other analyses. CONCLUSION: The study concludes that PCSK9 plays a significant role in the development of CM, and its inhibition is linked to a reduced risk of the disease.

PCSK9 causes inflammation and cGAS/STING pathway activation in diabetic nephropathy.

Our previous research revealed that an increase in PCSK9 is linked to aggravated inflammation in the kidneys of mice affected by a high-fat diet and streptozotocin (HFD/STZ) or in HGPA-induced HK-2 cells. Furthermore, the cGAS/STING pathway has been reported to be involved in diabetic nephropathy (DN). Therefore, in this study, we aimed to examine the correlation between the proinflammatory effect of PCSK9 and the cGAS/STING pathway in DN. We used PCSK9 mAbs to inhibit PCSK9 in vivo and PCSK9 siRNA in vitro and measured the inflammatory phenotype in HFD/STZ-treated mice or HGPA-induced HK-2 cells, and observed decreased blood urea nitrogen, creatinine, UACR, and kidney injury in response to the PCSK9 mAb in HFD/STZ-treated mice. Moreover, IL-1 ß, MCP-1, and TNF-α levels were reduced by the PCSK9 mAb in vivo and PCSK9 siRNA in vitro. We observed increased mtDNA damage and activation of the cGAS-STING signaling pathway during DN, as well as the downstream targets p-TBK1, p-NF-κB p65, and IL-1ß. In a further experiment with an HGPA-induced DN model in HK-2 cells, we revealed that mtDNA damage was increased, which led to the activation of the cGAS/STING system and its downstream targets. Notably, the cGAS-STING signaling pathway was inhibited by the PCSK9 mAb in vivo and PCSK9 siRNA in vitro. In addition, inhibition of STING with C-176 in HGPA-induced HK-2 cells markedly blocked inflammation. In conclusion, we report for the first time that PCSK9 triggers mitochondrial DNA damage and activates the cGAS-STING pathway in DN, which leads to a series of inflammation cascades. PCSK9-targeted intervention can effectively reduce DN inflammation and delay its progression. Moreover, the inhibition of STING significantly abrogated the inflammation triggered by HGPA in HK-2 cells.

Ebronucimab in Chinese patients with hypercholesterolemia---A randomized double-blind placebo-controlled phase 3 trial to evaluate the efficacy and safety of ebronucimab.

Randomized clinical trials (RCTs) of PCSK9 monoclonal antibody(mAb) specifically for Chinese patients have been limited. This multi-center RCT is to clarify the efficacy and safety of a novel mAb, Ebronucimab, in Chinese patients. Patients diagnosed with primary hypercholesterolemia, including Heterozygous Familial Hypercholesterolemia, or mixed dyslipidemia, were categorized by ASCVD risk and randomly assigned at a ratio of 2:1:2:1 to receive Ebronucimab 450 mg or matching placebo every 4 weeks (Q4W), or Ebronucimab 150 mg or matching placebo every 2 weeks (Q2W). The primary outcome was the percentage change of LDL-C from baseline to week 12 for all groups. The least squares mean reduction difference (95 %CI) in LDL-C from baseline to week 12 of Ebronucimab 450 mg Q4W and Ebronucimab 150 mg Q2W groups versus the placebo group was -59.13 (-64.103, -54.153) (Adjusted p<0.0001) and -60.43 (-65.450, -55.416) (Adjusted p<0.0001), respectively. Meanwhile, the Ebronucimab group exhibited notably high rates in reaching LDL-C goals of each cardiovascular risk stratification. In addition, Ebronucimab effectively improved other lipid panel. During the double-blind treatment period, relatively frequently reported adverse events (AEs) were injection site reactions (ISR), urinary tract infection, and hyperuricemia (Incidence rate are 6.9 %, 4.8 % and 3.5 %). Among treatment-associated AEs, only injection site reactions (ISR) occurred more in the dose groups. In conclusion, Ebronucimab, with either 450 mg Q4W or 150 mg Q2W doses, demonstrated significant efficacy in lowering serum LDL-C level with a favorable safety and immunogenicity profile among hypercholesterolemic patients.

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

INTRODUCTION: Curative 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. METHODS: One hundred sixty-three patients with resectable NSCLC were retrospectively reviewed, and PCSK9 expression of resected NSCLC was analyzed by immunohistochemistry using tissue microarrays. RESULTS: PCSK9 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. CONCLUSIONS: High 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.

Potential use of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition and prevention method in viral infection.

Cellular lipid membranes serve as the primary barrier preventing viral infection of the host cell and provide viruses with a critical initial point of contact. Occasionally, viruses can utilize lipids as viral receptors. Viruses depend significantly on lipid rafts for infection at virtually every stage of their life cycle. The pivotal role that proprotein convertase subtilisin/kexin Type 9 (PCSK9) plays in cholesterol homeostasis and atherosclerosis, primarily by post-transcriptionally regulating hepatic low-density lipoprotein receptor (LDLR) and promoting its lysosomal degradation, has garnered increasing interest. Conversely, using therapeutic, fully humanized antibodies to block PCSK9 leads to a significant reduction in high LDL cholesterol (LDL-C) levels. The Food and Drug Administration (FDA) has approved PCSK9 inhibitors, including inclisiran (Leqvio®), alirocumab (Praluent), and evolocumab (Repatha). At present, active immunization strategies targeting PCSK9 present a compelling substitute for passive immunization through the administration of antibodies. In addition to the current inquiry into the potential therapeutic application of PCSK9 inhibition in human immunodeficiency virus (HIV)-infected patients for hyperlipidemia associated with HIV and antiretroviral therapy (ART), preclinical research suggests that PCSK9 may also play a role in inhibiting hepatitis C virus (HCV) replication. Furthermore, PCSK9 inhibition has been suggested to protect against dengue virus (DENV) potentially and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viruses. Recent evidence regarding the impact of PCSK9 on a variety of viral infections, including HCV, HIV, DENV, and SARS-CoV-2, is examined in this article. As a result, PCSK9 inhibitors and vaccines may serve as viable host therapies for viral infections, as our research indicates that PCSK9 is significantly involved in the pathogenesis of viral infections.

New Loss-of-Function Mutations in PCSK9 Reduce Plasma LDL Cholesterol.

BACKGROUND: Lower plasma levels of LDL (low-density lipoprotein) cholesterol (LDL-C) can reduce the risk of atherosclerotic cardiovascular disease. The loss-of-function mutations in PCSK9 (proprotein convertase subtilisin/kexin type 9) have been known to associate with low LDL-C in many human populations. PCSK9 genetic variants in Chinese Uyghurs who are at high risk of atherosclerotic cardiovascular disease due to their dietary habits have not been reported. METHODS: The study involved the whole-exome and target sequencing of college students from Uyghur and other ethnic groups in Xinjiang, China, for the association of PCSK9 loss-of-function mutations with low plasma levels of LDL-C. The mechanisms by which the identified mutations affect the function of PCSK9 were investigated in cultured cells using biochemical and cell assays. The causal effects of the identified PCSK9 mutations on LDL-C levels were verified in mice injected with adeno-associated virus expressing different forms of PCSK9 and fed a high-cholesterol diet. RESULTS: We identified 2 PCSK9 mutations-E144K and C378W-in Chinese Uyghurs with low plasma levels of LDL-C. The E144K and C378W mutations impaired the maturation and secretion of the PCSK9 protein, respectively. Adeno-associated virus-mediated expression of E144K and C378W mutants in Pcsk9 KO (knockout) mice fed a high-cholesterol diet also hampered PCSK9 secretion into the serum, resulting in elevated levels of LDL receptor in the liver and reduced levels of LDL-C in the serum. CONCLUSIONS: Our study shows that E144K and C378W are PCSK9 loss-of-function mutations causing low LDL-C levels in mice and probably in humans as well.

Real-World Clinical Profile of Patients Prescribed Evolocumab in Japan.

BACKGROUND: Real-world utilization data for evolocumab, the first proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor to be introduced in Japan in 2016, to date are limited. This study aimed to clarify the current real-world patient user profiles of evolocumab based on large-scale health claims data. METHODS AND RESULTS: This retrospective database study examined patients from a health administrative database (MDV database) who initiated evolocumab between April 2016 (baseline) and November 2021. Characteristics and clinical profiles of this patient population are described. In all, 4,022 patients were included in the final analysis. Most evolocumab prescriptions occurred in the outpatient setting (3,170; 78.82%), and 940 patients (23.37%) had a recent diagnosis of familial hypercholesterolemia. Common recent atherosclerotic cardiovascular disease events at baseline included myocardial infarction (1,633; 40.60%), unstable angina (561; 13.95%), and ischemic stroke (408; 10.14%). Comorbidity diseases included hypertension (2,504; 62.26%), heart failure (1,750; 43.51%), diabetes (1,199; 29.81%), and chronic kidney disease (297; 7.38%). Among the lipid-lowering regimens concomitant with evolocumab, ezetimibe+statin was used most frequently (1,281; 31.85%), followed by no concomitant lipid-lowering regimen (1,190; 29.59%), statin (950; 23.62%), and ezetimibe (601; 14.94%). The median evolocumab treatment duration for all patients was 260 days (interquartile range 57-575 days). CONCLUSIONS: This study provides real-world insights into evolocumab utilization in Japan for optimizing patient care and adherence to guideline-based therapies to better address hypercholesterolemia in Japan.

Enhanced Plaque Stabilization Effects of Alirocumab　- Insights From Artificial Intelligence-Aided Optical Coherence Tomography Analysis of the Alirocumab for Thin-Cap Fibroatheroma in Patients With Coronary Artery Disease Estimated by Optical Coherence Tomography (ALTAIR) Study.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 inhibitors stabilize vulnerable plaque, reducing cardiovascular events. However, manual optical coherence tomography (OCT) analysis of drug efficacy is challenging because of signal attenuation within lipid plaques. METHODS AND RESULTS: Twenty-four patients with thin-cap fibroatheroma were prospectively enrolled and randomized to receive alirocumab (75 mg every 2 weeks) plus rosuvastatin (10 mg/day) or rosuvastatin (10 mg/day) alone. OCT images at baseline and 36 weeks were analyzed manually and with artificial intelligence (AI)-aided software. AI-aided OCT analysis showed significantly greater percentage changes in the alirocumab+rosuvastatin vs. rosuvastatin-alone group in fibrous cap thickness (FCT; median [interquartile range] 212.3% [140.5-253.5%] vs. 88.6% [63.0-119.6%]; P=0.006) and lipid volume (median [interquartile range] -30.8% [-51.8%, -16.6%] vs. -2.1% [-21.6%, 4.3%]; P=0.015). Interobserver reproducibility for changes in minimum FCT and lipid index was relatively low for manual analysis (interobserver intraclass correlation coefficient [ICC] 0.780 and 0.499, respectively), but high for AI-aided analysis (interobserver ICC 0.999 and 1.000, respectively). Agreements between manual and AI-aided OCT analyses of FCT and the lipid index were acceptable (concordance correlation coefficients 0.859 and 0.833, respectively). CONCLUSIONS: AI-aided OCT analysis objectively showed greater plaque stabilization of adding alirocumab to rosuvastatin. Our results highlight the benefits of a fully automated AI-assisted approach for assessing drug efficacy, offering greater objectivity in evaluating serial changes in plaque stability vs. conventional OCT assessment.