Daily Cardiology Research Analysis
Three impactful cardiology studies stood out today: a mechanistic discovery that Sirtuin-1 directly deacetylates hepatic PCSK9 to enhance LDL receptor function and reduce atherosclerosis; a nationwide registry study revealing left-digit bias in creatinine guiding contrast dosing during PCI; and translational evidence that the peptide hormone ELABELA mitigates atherosclerosis by restoring macrophage M1/M2 balance.
Summary
Three impactful cardiology studies stood out today: a mechanistic discovery that Sirtuin-1 directly deacetylates hepatic PCSK9 to enhance LDL receptor function and reduce atherosclerosis; a nationwide registry study revealing left-digit bias in creatinine guiding contrast dosing during PCI; and translational evidence that the peptide hormone ELABELA mitigates atherosclerosis by restoring macrophage M1/M2 balance.
Research Themes
- Mechanistic lipid regulation via SIRT1–PCSK9 deacetylation
- Cognitive bias and quality improvement in PCI contrast management
- Immunomodulatory therapy in atherosclerosis (ELABELA and macrophage polarization)
Selected Articles
1. Sirtuin-1 directly binds and deacetylates hepatic PCSK9 thereby promoting the inhibition of LDL receptor degradation.
In ApoE−/− mice, systemic SIRT1 augmentation reduced LDL-C and plaque burden by directly binding and deacetylating hepatic PCSK9 at Lys243/Lys421/Lys506, thereby preserving LDLR function. In ACS patients, higher plasma SIRT1 correlated with lower PCSK9 and reduced MACE risk, positioning SIRT1–PCSK9 acetylation as a modifiable axis in atherosclerosis.
Impact: This study uncovers a first-in-class mechanism whereby SIRT1 deacetylates PCSK9 to modulate LDLR biology, linking a fundamental epigenetic enzyme to lipoprotein regulation with translational human data.
Clinical Implications: Pharmacologic SIRT1 activation or strategies to modulate PCSK9 acetylation could complement statins/PCSK9 inhibitors to further lower LDL-C and stabilize plaques; plasma SIRT1 may serve as a risk biomarker.
Key Findings
- Recombinant SIRT1 increased hepatic LDLR, lowered plasma LDL-C, and reduced plaque progression in ApoE−/− mice.
- SIRT1 directly bound hepatic PCSK9 and deacetylated Lys243, Lys421, and Lys506, decreasing PCSK9 activity.
- Triple deacetylation-mimetic mutation (3KR) attenuated SIRT1-induced PCSK9 activity and increased 125I-LDL association with LDLR.
- In ACS patients, higher plasma SIRT1 inversely correlated with PCSK9 and associated with reduced MACE risk.
Methodological Strengths
- Randomized in vivo intervention in ApoE−/− mice with prespecified dosing and duration.
- Orthogonal mechanistic validation including direct binding and mass spectrometric site mapping of PCSK9 acetylation.
- Translational linkage with human ACS plasma biomarker correlations.
Limitations
- Human data are observational (baseline biomarkers) without interventional validation.
- Murine sample sizes and dosing generalizability to humans remain uncertain.
- Long-term safety and off-target effects of SIRT1 augmentation were not assessed.
Future Directions: Quantify PCSK9 acetylation states in human liver and plasma, test SIRT1 activators or acetylation modulators in early-phase lipid-lowering trials, and evaluate combination strategies with statins/PCSK9 inhibitors.
AIMS: Low-density lipoprotein (LDL)-cholesterol is causally involved in atherosclerotic cardiovascular disease (ASCVD) pathogenesis. Pharmacological activation of the intracellular NAD + -dependent deacetylase Sirtuin-1 (SIRT1) reduces plasma LDL-cholesterol levels by increasing hepatic LDL-receptor (LDLR) expression, which intriguingly associates with atheroprotective effects. Recent studies have identified the presence of SIRT1 in plasma, however, its effects remain elusive. We found that plasma levels of SIRT1 to be decreased in atherosclerotic mice compared with wild-type controls and aimed to investigate the therapeutic potential of systemic SIRT1 restoration on lipid metabolism and plaque burden in atherosclerotic mice and dissect the underlying molecular mechanisms involved. METHODS AND RESULTS: Twelve-week-old apolipoprotein E-deficient (ApoE-/-) mice fed a high-cholesterol diet (1.25% w/w) were randomized to receive recombinant murine SIRT1(rmSIRT1) (n = 6; 0.3 mg/kg BW i.p.) or vehicle (n = 6; PBS) every third day over 4 weeks. Boosting systemic SIRT1 levels increased hepatic LDLR protein expression, reduced plasma LDL-cholesterol levels and decreased plaque progression in ApoE-/- mice. Yet, rmSIRT1 treatment did not change hepatic proprotein convertase subtilisin/kexin type 9 (PCSK9) expression but notably increased its deacetylated levels. Mechanistically, rmSirt1 directly bound to hepatic PCSK9 thereby promoting PCSK9 deacetylation involving 3 sites, namely Lys243, Lys421, and Lys506, as shown by mass spectrometric analyses. In vitro mutagenesis to triple deacetylation mimetic (3KR) reduced SIRT1-induced PCSK9 activity, as evidenced by increased cellular binding and association of 125I-LDL to hepatic LDLR. Finally, plasma levels of SIRT1 and PCSK9 were assessed at baseline in patients with acute coronary syndromes. In these patients, plasma SIRT1 levels correlated inversely with PCSK9 with high SIRT1 levels conferring a reduced risk of major adverse cardiovascular events (MACE). CONCLUSION: SIRT1 directly binds hepatic PCSK9 and decreases its activity by deacetylation, thereby enhancing LDL-cholesterol clearance by hepatic LDLR upregulation. Boosting circulating SIRT1 exerts atheroprotective effects in mice, with high levels associating with improved prognosis in patients with established ASCVD.
2. Left-Digit Bias in Serum Creatinine Levels and Contrast Administration: A Nationwide Cohort Study Using a Japanese Percutaneous Coronary Intervention Registry.
In 735,696 PCIs, contrast volume dropped abruptly when creatinine crossed integer thresholds (1.0 and 2.0 mg/dL), but did not vary meaningfully across predicted AKI risk levels, indicating left-digit bias in dosing decisions. Implementing formal AKI risk–based protocols could mitigate cognitive bias and better align contrast use with true risk.
Impact: This national analysis exposes a systematic cognitive bias affecting a modifiable procedural factor with direct patient safety implications, providing a concrete target for quality improvement in PCI.
Clinical Implications: Adopt EHR-integrated AKI risk calculators and standardized, risk-based contrast limits; de-biasing checklists and automated prompts can reduce reliance on raw creatinine integers and minimize AKI risk.
Key Findings
- Median contrast volume was 117 mL across 735,696 PCI procedures.
- Contrast volume decreased sharply when creatinine exceeded 1.0 mg/dL (−2.2 mL) and 2.0 mg/dL (−4.7 mL), but not at 3.0 mg/dL.
- Minimal variation in contrast use across predicted AKI risk levels suggests reliance on creatinine integers rather than formal risk stratification.
Methodological Strengths
- Very large, contemporary nationwide registry with standardized data capture.
- Predefined threshold analysis around integer creatinine values to detect left-digit bias.
- Use of a validated AKI risk score for contextual comparison.
Limitations
- Observational design cannot establish causality between bias and outcomes.
- Primary endpoint was contrast volume; AKI clinical outcomes were not directly analyzed in this report.
Future Directions: Test de-biasing interventions (decision support, education, feedback) in pragmatic trials; link contrast dosing patterns to actual AKI outcomes; embed risk-based contrast caps in PCI workflows.
BACKGROUND: Contemporary quality initiatives emphasize minimizing contrast volume as a key modifiable factor to prevent acute kidney injury (AKI) following percutaneous coronary intervention (PCI). Left-digit bias is a cognitive bias where the leftmost digit of a number disproportionately influences decisions. This bias may unintentionally affect contrast administration when interpreting laboratory values like serum creatinine. Therefore, we aim to assess the impact of left-digit bias in serum creatinine level on contrast volume in PCI. METHODS: We analyzed patients undergoing PCI between January 2018 and December 2022 using the Japanese nationwide prospective multicenter registry. The primary outcome was PCI contrast volume. Left-digit bias was assessed by comparing contrast volume differences at specific creatinine thresholds (eg, 1.0 mg/dL and 2.0 mg/dL). AKI risks were calculated by a validated risk scoring system. RESULTS: Among 735 696 PCI procedures, the median contrast volume was 117 mL (interquartile range 85-157 mL). Analysis of average contrast volume revealed a sharp decrease at baseline creatinine levels above versus less than 1 mg/dL (mean difference, 2.2 mL [95% CI, 1.6-2.8]) and 2 mg/dL (4.7 [95% CI, 1.6-7.8]) but not at 3 mg/dL (-2.0 [95% CI, -10.0 to 6.0]). Despite differences at integer thresholds of creatinine, minimal variation across AKI risk levels suggests operators prioritize creatinine values over predicted AKI risk. CONCLUSIONS: Our study provides valuable insights into contemporary trends in contrast volume for PCI and identifies left-digit bias in creatinine interpretation affecting contrast administration. Formal risk stratification is essential to optimize contrast use for AKI prevention.
3. ELABELA Ameliorates Atherosclerosis Through Restoring the M1/M2 Macrophage Balance in
Plasma ELABELA is reduced in atherosclerosis and inversely correlates with MMP2/MMP9. In high-fat diet models, the ELA-21 peptide reduced plaque burden and stabilized lesions by restoring macrophage M1/M2 balance and modulating ACE/ACE2 and pattern recognition receptor signaling.
Impact: Identifying ELABELA as a biomarker and therapeutic modulator of macrophage polarization addresses a core inflammatory mechanism in atherosclerosis with translational potential.
Clinical Implications: ELABELA measurement could augment risk stratification, and ELA-21 or related agonists may evolve as adjunctive anti-atherosclerotic therapies aimed at immune remodeling and plaque stabilization.
Key Findings
- Plasma ELABELA levels are significantly reduced in atherosclerosis and inversely correlate with MMP2/MMP9.
- ELA-21 administration in high-fat diet atherosclerosis models inhibits plaque formation and promotes a more stable phenotype.
- Mechanistically, benefits align with restoring M1/M2 macrophage balance, increasing macrophage ACE/ACE2 expression, and inhibiting PRR signaling.
Methodological Strengths
- Integrated human biomarker cohort with mechanistic in vivo validation in atherosclerosis models.
- Convergent readouts spanning plaque burden and stability, protease activity (MMP2/9), and immune cell polarization.
- Clear, targetable pathway hypotheses (ACE/ACE2 and PRR modulation).
Limitations
- Cohort size and detailed clinical characteristics are not reported in the abstract.
- Duration and dosing details of ELA-21 treatment are not specified in the abstract.
- Clinical efficacy and safety of ELABELA-based therapy remain to be established in humans.
Future Directions: Define optimal dosing and duration in preclinical models, conduct phase 1 safety/pharmacodynamic studies, and test ELABELA-guided risk stratification and ELA-21 adjunctive therapy in clinical trials.
BACKGROUND: Atherosclerosis is a progressive arterial disease characterized by chronic inflammation and plaque formation in blood vessel walls. ELABELA, an endogenous ligand for the G protein-coupled receptor APJ (apelin peptide jejunum, apelin receptor), has multiple pharmacological activities for protecting the cardiovascular system. This study aimed to determine the potential antiatherosclerotic effect of ELABELA and reveal the underlying mechanisms. METHODS: We enrolled a cohort consisting of patients with and without atherosclerosis to determine the relationship between plasma ELABELA levels and atherosclerosis severity. The potential therapeutic action of ELA-21 (ELABELA-21) on atherosclerosis in high-fat diet-fed RESULTS: Plasma ELABELA levels were significantly reduced and negatively correlated with plasma MMP2 (matrix metallopeptidase 2) and MMP9 (matrix metallopeptidase 9) levels in patients with atherosclerosis and high-fat diet-induced atherosclerotic CONCLUSIONS: Our data highlighted the diagnostic and therapeutic potential of ELABELA on atherosclerosis. ELA-21 protects against atherosclerosis by inhibiting atherosclerotic plaque formation and promoting a more stable plaque phenotype, possibly via restoring the M1/M2 macrophage balance, enhancing macrophage ACE and ACE2 expression, and inhibiting the PRR system. ELABELA may be a novel diagnostic biomarker and candidate therapeutic target for atherosclerosis.