Daily Cardiology Research Analysis
Mechanistic studies uncovered new drivers of atherogenesis and endothelial dysfunction, while a large clinical cohort clarified that residual inflammatory risk—not triglycerides—dominates post-PCI events despite well-controlled LDL cholesterol. Specifically, erythrocyte-derived extracellular vesicles transfer arginase-1 to endothelium in type 2 diabetes, and macrophage HM13/SPP promotes foamy macrophage formation and atherosclerosis by degrading HO-1.
Summary
Mechanistic studies uncovered new drivers of atherogenesis and endothelial dysfunction, while a large clinical cohort clarified that residual inflammatory risk—not triglycerides—dominates post-PCI events despite well-controlled LDL cholesterol. Specifically, erythrocyte-derived extracellular vesicles transfer arginase-1 to endothelium in type 2 diabetes, and macrophage HM13/SPP promotes foamy macrophage formation and atherosclerosis by degrading HO-1.
Research Themes
- Endothelial dysfunction mechanisms in diabetes
- Atherogenesis via ER proteostasis and macrophage biology
- Residual inflammatory risk after PCI despite LDL control
Selected Articles
1. Erythrocyte-derived extracellular vesicles induce endothelial dysfunction through arginase-1 and oxidative stress in type 2 diabetes.
Using RBC-derived extracellular vesicles from T2D patients, the authors show that EV cargoed arginase-1 is transferred to endothelial cells, increasing oxidative stress and impairing endothelium-dependent relaxation. Inhibition of arginase (within EVs or vascular) or oxidative stress mitigated dysfunction, implicating RBC-EVs as key mediators of diabetic endothelial injury.
Impact: This study defines a concrete, targetable mechanism linking erythrocytes to vascular dysfunction in T2D via EV transfer of arginase-1. It opens therapeutic avenues for arginase inhibition or EV uptake modulation to restore endothelial health.
Clinical Implications: Arginase-1 and EV-mediated signaling emerge as therapeutic targets to improve endothelial function in T2D; arginase inhibitors or strategies reducing RBC-EV uptake could complement standard cardiometabolic care.
Key Findings
- T2D RBC-derived EVs are taken up more avidly by endothelial cells despite lower EV production.
- T2D RBC-EVs impair endothelium-dependent relaxation; arginase inhibition (in EVs or vessel) and antioxidant strategies attenuate dysfunction.
- Arginase-1 is present in RBC-EVs and increases in endothelial cells after exposure, even with endothelial Arg1 mRNA silencing and in Arg1-deficient endothelium.
- Mechanism involves EV transfer of arginase-1 leading to oxidative stress and endothelial dysfunction.
Methodological Strengths
- Use of human patient-derived RBC-EVs with functional endothelial assays and vasoreactivity testing.
- Genetic validation using endothelial Arg1-knockout mice to confirm EV-mediated protein transfer effects.
Limitations
- Clinical donor sample size and heterogeneity are not detailed in the abstract; translational dosing and pharmacology require further study.
- Predominantly ex vivo/in vitro mechanistic work; in vivo therapeutic modulation of EV pathways was not reported.
Future Directions: Evaluate arginase inhibition and EV uptake blockade in vivo for vascular endpoints in T2D, and test circulating RBC-EV arginase-1 as a biomarker of endothelial risk.
Red blood cells (RBCs) induce endothelial dysfunction in type 2 diabetes (T2D), but the mechanism by which RBCs communicate with the endothelium is unknown. This study tested the hypothesis that extracellular vesicles (EVs) secreted by RBCs act as mediators of endothelial dysfunction in T2D. Despite a lower production of EVs derived from RBCs of T2D patients (T2D RBC-EVs), their uptake by endothelial cells was greater than that of EVs derived from RBCs of healthy individuals (H RBC-EVs). T2D RBC-EVs impaired endothelium-dependent relaxation, and this effect was attenuated following inhibition of arginase in EVs. Inhibition of vascular arginase or oxidative stress also attenuated endothelial dysfunction induced by T2D RBC-EVs. Arginase-1 was detected in RBC-derived EVs, and arginase-1 and oxidative stress were increased in endothelial cells following coincubation with T2D RBC-EVs. T2D RBC-EVs also increased arginase-1 protein in endothelial cells following mRNA silencing and in the endothelium of aortas from endothelial cell arginase-1-knockout mice. It is concluded that T2D-RBCs induce endothelial dysfunction through increased uptake of EVs that transfer arginase-1 from RBCs to the endothelium to induce oxidative stress and endothelial dysfunction. These results shed important light on the mechanism underlying endothelial dysfunction mediated by RBCs in T2D.
2. Macrophage HM13/SPP Enhances Foamy Macrophage Formation and Atherogenesis.
Network analysis and mechanistic studies identify HM13/SPP as a macrophage driver of lipid loading and foamy cell formation by promoting ERAD-dependent degradation of HO-1. Myeloid HM13 overexpression accelerates atherosclerosis, whereas knockout is protective; AIP suppresses HM13 via AHR–p38–c-JUN signaling.
Impact: Reveals a previously unrecognized ERAD–HO-1 axis in foamy macrophage biology and atherogenesis, nominating HM13/SPP as a targetable node downstream of AIP/AHR signaling.
Clinical Implications: Therapeutic modulation of HM13/SPP or reinforcement of HO-1 stability may reduce foam cell burden and atherosclerosis; AHR–AIP pathway tuning could offer anti-atherogenic strategies.
Key Findings
- AIP negatively correlates with HM13/SPP in human atherosclerosis (STAGE cohort), oxLDL-treated macrophages, and plaque foam cells.
- AIP via AHR chaperoning inhibits p38–c-JUN-mediated HM13 transactivation, reducing macrophage lipid accumulation.
- Myeloid HM13/SPP overexpression increases foam cell formation and atherogenesis in vivo; knockout has opposite, protective effects.
- HM13/SPP promotes ERAD-dependent proteasomal degradation of HO-1, linking ER proteostasis to foam cell biology.
Methodological Strengths
- Integrates patient transcriptomics (WGCNA) with in vitro and in vivo myeloid-specific gain- and loss-of-function models.
- Mechanistic dissection of signaling (AHR–p38–c-JUN) and ERAD–HO-1 pathway with multi-level validation.
Limitations
- Pharmacologic HM13/SPP inhibition was not tested; off-target or systemic effects remain to be characterized.
- Translational validation in human intervention studies is lacking.
Future Directions: Develop selective HM13/SPP inhibitors or HO-1 stabilizers; assess efficacy in preclinical atherosclerosis models and explore AHR–AIP pathway modulation in humans.
Aryl Hydrocarbon Receptor-Interacting Protein (AIP) reduces macrophage cholesterol-ester accumulation and may prevent atherogenic foamy macrophage formation. Analyzing AIP-associated regulatory gene networks can aid in identifying key regulatory mechanism(s) underlying foamy macrophage formation. A weighted gene co-expression network analysis on the Stockholm Atherosclerosis Gene Expression (STAGE) patient cohort identifies AIP as a negative correlate of Histocompatibility Minor 13 (HM13), which encodes the ER-associated degradation (ERAD) protein Signal Peptide Peptidase (HM13/SPP). The negative correlation between AIP and HM13/SPP on mRNA and protein levels is validated in oxLDL-stimulated macrophages and human plaque foamy macrophages. Mechanistically, AIP, via its chaperone interaction with Aryl Hydrocarbon Receptor (AHR), inhibits p38-c-JUN-mediated HM13 transactivation, thereby suppressing macrophage lipid accumulation. Myeloid HM13/SPP overexpression enhances oxLDL-induced foamy macrophage formation in vitro as well as atherogenesis and plaque foamy macrophage load in vivo, while myeloid HM13/SPP knockout produces the opposite effects. Mechanistically, myeloid HM13/SPP enhances oxLDL-induced foamy macrophage formation in vitro as well as atherogenesis and plaque foamy macrophage load in vivo via promoting ERAD-mediated proteasomal degradation of the metabolic regulator Heme Oxygenase-1 (HO-1). In conclusion, AIP downregulates macrophage HM13/SPP, a driver of oxLDL-induced lipid loading, foamy macrophage generation, and atherogenesis.
3. Prognostic impact of residual inflammatory and triglyceride risk in statin-treated patients with well-controlled LDL cholesterol and atherosclerotic cardiovascular disease.
In 9,446 statin-treated PCI patients with LDL-C <70 mg/dL, elevated hs-CRP (≥2 mg/L) with or without TG elevation predicted higher 1-year MACE, driven largely by all-cause mortality. Isolated residual TG risk did not increase events, underscoring inflammation—not triglycerides—as the dominant residual risk.
Impact: Shifts risk stratification focus beyond LDL to inflammation in a large, contemporary PCI cohort, informing prioritization of anti-inflammatory prevention strategies.
Clinical Implications: Consider hs-CRP to identify high-risk patients despite LDL control and evaluate anti-inflammatory interventions; isolated hypertriglyceridemia may warrant individualized decisions rather than broad escalation.
Key Findings
- Among statin-treated PCI patients with LDL-C <70 mg/dL, 31.9% had residual inflammatory risk and 5.7% had combined TG+inflammatory risk.
- Residual inflammatory risk (hs-CRP ≥2 mg/L), alone or combined with elevated TGs, was associated with higher 1-year MACE after multivariable adjustment, mainly driven by all-cause mortality.
- Isolated residual TG risk (TG ≥150 mg/dL with hs-CRP <2 mg/L) did not differ from no residual risk in MACE.
Methodological Strengths
- Large, real-world cohort with contemporary PCI and strict LDL-C threshold (<70 mg/dL).
- Multivariable Cox modeling with clear risk group definitions using hs-CRP and TG.
Limitations
- Observational design with potential residual confounding; single time-point biomarker assessment.
- Generalizability beyond PCI populations and to non-statin therapies requires caution.
Future Directions: Prospective trials testing anti-inflammatory therapies in post-PCI patients with elevated hs-CRP despite LDL control; evaluate dynamic hs-CRP trajectories and multi-marker panels.
AIMS: Identifying alternative contributors to the residual risk of atherosclerotic cardiovascular disease (ASCVD) beyond LDL cholesterol (LDL-C) levels is crucial. We investigated the relative impact of triglycerides (TGs) and high-sensitivity C-reactive protein (hs-CRP) on outcomes in statin-treated patients with well-controlled LDL-C undergoing percutaneous coronary intervention (PCI) for established ASCVD. METHODS AND RESULTS: We included 9446 statin-treated patients with LDL-C < 70 mg/dL undergoing PCI between 2012 and 2022, stratified into four groups: (i) no residual risk (TG <150 mg/dL + hs-CRP <2 mg/L); (ii) residual TG risk (TG ≥150 mg/dL + hs-CRP <2 mg/L); (iii) residual inflammatory risk (TG <150 mg/dL + hs-CRP ≥2 mg/L); and (iv) residual TG and inflammatory risk (TG ≥150 mg/dL + hs-CRP ≥2 mg/L). The primary endpoint was major adverse cardiovascular events (MACE) at 1 year, consisting of all-cause mortality, myocardial infarction, or stroke. Cox regression analysis was performed, using the no residual risk group as a reference. Of the total population, 5339 (56.5%) had no residual risk, 555 (5.9%) presented residual TG risk, 3009 (31.9%) had residual inflammatory risk, and 543 (5.7%) exhibited residual combined risk. After multivariable adjustment, patients with residual inflammatory or combined risk showed a significantly higher hazard of MACE, mainly driven by all-cause mortality. No significant difference was observed between patients with residual TG risk and those with no residual risk. CONCLUSION: In statin-treated patients with well-controlled LDL-C undergoing PCI, residual inflammatory risk-alone or in combination with residual TG risk-was associated with a higher incidence of MACE, highlighting the need for targeted preventive strategies beyond LDL-C lowering. This study examines the relative contribution of residual inflammatory risk, measured by high-sensitivity C-reactive protein (hs-CRP) ≥ 2 mg/L and residual triglyceride (TG) risk, measured by TG ≥150 mg/dL—whether isolated or combined—to predict cardiovascular outcomes in a large, real-world cohort of very high-risk patients, specifically those undergoing percutaneous coronary intervention for established atherosclerotic cardiovascular disease, all receiving statins and achieving well-controlled LDL cholesterol (LDL-C). Residual TG risk alone did not increase the risk of major cardiovascular events.Patients with residual inflammatory risk—whether isolated or combined with elevated TGs—faced a higher risk of major adverse cardiovascular events, primarily due to increased rates of all-cause mortality.These findings suggest that hs-CRP is a more reliable marker than TGs for risk stratification, emphasizing the need for targeted preventive strategies beyond LDL-C lowering.