Recent Updates on the Use of PCSK9 Inhibitors in Patients with Atherosclerotic Cardiovascular Disease.

PURPOSE OF REVIEW: Atherosclerotic cardiovascular disease (ASCVD) is caused by elevated levels of low-density lipoprotein cholesterol (LDL-C). Although statins significantly reduce ASCVD risk, there remains a high degree of residual risk in statin-treated patients. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition has emerged as a significant therapeutic target for further lowering of LDL-C when used in combination with statins. The purpose of this review is to provide an update on recent evidence supporting the use of PCSK9 inhibitors in patients with ASCVD. RECENT FINDINGS: Alirocumab and evolocumab were approved by the US Food and Drug Administration in 2015. Multiple phase II and III studies have demonstrated that these agents reduce LDL-C levels by up to 60% and are relatively safe, with the exception of injection site reactions. Additionally, two randomized controlled clinical trials have demonstrated that both alirocumab and evolocumab reduce ASCVD events when used in combination with statin therapy compared to statin alone. In light of this evidence, the 2018 Cholesterol Guideline incorporated PCSK9 inhibitors into the treatment algorithm for select secondary prevention patients unable to achieve an LDL-C below 70 mg/dL despite maximally tolerated statin plus ezetimibe. Although PCSK9 inhibitors provide substantial reductions in LDL-C levels and reduce ASCVD events in secondary prevention populations, the cost-effectiveness of alirocumab and evolocumab limit widespread use. Additional research is needed to explore the role of PCSK9 inhibitors in other populations, including primary prevention, patients unable to tolerate statins, and acute myocardial infarction.

Synaptic dysfunction and abnormal behaviors in mice lacking major isoforms of Shank3.

SHANK3 is a synaptic scaffolding protein enriched in the postsynaptic density (PSD) of excitatory synapses. Small microdeletions and point mutations in SHANK3 have been identified in a small subgroup of individuals with autism spectrum disorder (ASD) and intellectual disability. SHANK3 also plays a key role in the chromosome 22q13.3 microdeletion syndrome (Phelan-McDermid syndrome), which includes ASD and cognitive dysfunction as major clinical features. To evaluate the role of Shank3 in vivo, we disrupted major isoforms of the gene in mice by deleting exons 4-9. Isoform-specific Shank3(e4-9) homozygous mutant mice display abnormal social behaviors, communication patterns, repetitive behaviors and learning and memory. Shank3(e4-9) male mice display more severe impairments than females in motor coordination. Shank3(e4-9) mice have reduced levels of Homer1b/c, GKAP and GluA1 at the PSD, and show attenuated activity-dependent redistribution of GluA1-containing AMPA receptors. Subtle morphological alterations in dendritic spines are also observed. Although synaptic transmission is normal in CA1 hippocampus, long-term potentiation is deficient in Shank3(e4-9) mice. We conclude that loss of major Shank3 species produces biochemical, cellular and morphological changes, leading to behavioral abnormalities in mice that bear similarities to human ASD patients with SHANK3 mutations.

Effect of pain management on immunization efficacy in mice.

Immunization with complete Freund adjuvant (CFA) or incomplete Freund adjuvant (IFA) is commonly viewed as painful, yet rodents may not receive analgesics due to concerns that these drugs affect the desired immune responses. Here we tested the hypothesis that pain associated with immunization with CFA or IFA in mice can be relieved without compromising the effectiveness of the immune response. After subcutaneous immunization in the leg with antigen in CFA or IFA, mice were assessed for signs of pain by using behavioral tests, including unrestricted locomotion in an open field, forced running on an automated treadmill, and voluntary wheel running. Effects of the analgesics acetaminophen, meloxicam, and buprenorphine on behavioral and antibody responses were assessed after primary and secondary immunization with the model antigen ovalbumin and after repeated immunization with a limiting dose of recombinant protective antigen from Bacillus anthracis. Open field activity and the distance traveled during forced gait analysis and voluntary wheel running both decreased after immunization. Treatment with each of the analgesics normalized some but not all of these behaviors but did not decrease the mean or maximal antibody titer after primary or repeated immunization with a moderate dose of ovalbumin or after repeated immunization with a limiting dose of protective antigen. In summary, after immunization with CFA or IFA, mice showed behavioral responses suggestive of pain. Acetaminophen, meloxicam, and buprenorphine attenuated these effects without decreasing antibody responses. Therefore, the use of these analgesics for managing rodent pain associated with CFA- or IFA-containing vaccines can be encouraged.