Macrophage KLF15 prevents foam cell formation and atherosclerosis via transcriptional suppression of OLR-1.

BACKGROUND: Macrophage-derived foam cells are a hallmark of atherosclerosis. Scavenger receptors, including lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (OLR-1), are the principal receptors responsible for the uptake and modification of LDL, facilitating macrophage lipid load and the uptake of oxidized LDL by arterial wall cells. Krüppel-like factor 15 (KLF15) is a transcription factor that regulates the expression of genes by binding to the promoter during transcription. Therefore, this study aimed to investigate the precise role of macrophage KLF15 in atherogenesis. METHODS: We used two murine models of atherosclerosis: mice injected with an adeno-associated virus (AAV) encoding the Asp374-to-Tyr mutant version of human PCSK9, followed by 12 weeks on a high-fat diet (HFD), and ApoE-/-- mice on a HFD. We subsequently injected mice with AAV-KLF15 and AAV-LacZ to assess the role of KLF15 in the development of atherosclerosis in vivo. Oil Red O, H&E, and Masson's trichome staining were used to evaluate atherosclerotic lesions. Western blots and RT-qPCR were used to assess protein and mRNA levels, respectively. RESULTS: We determined that KLF15 expression was downregulated during atherosclerosis formation, and KLF15 overexpression prevented atherosclerosis progression. KLF15 expression levels did not affect body weight or serum lipid levels in mice. However, KLF15 overexpression in macrophages prevented foam cell formation by reducing OLR-1-meditated lipid uptake. KLF15 directly targeted and transcriptionally downregulated OLR-1 levels. Restoration of OLR-1 reversed the beneficial effects of KLF15 in atherosclerosis. CONCLUSION: Macrophage KLF15 transcriptionally downregulated OLR-1 expression to reduce lipid uptake, thereby preventing foam cell formation and atherosclerosis. Thus, our results suggest that KLF15 is a potential therapeutic target for atherosclerosis.

Nadir oxygen delivery during cardiopulmonary bypass in acute type A aortic dissection repair.

Background: Acute type A aortic dissection (ATAAD) is associated with high mortality. Previous studies found that maintaining a high level of oxygen delivery (DO2) could decrease the postoperative mortality, but the minimum threshold of DO2 remained unclear. The present study aimed to investigate the relationship between maintaining intraoperative DO2 ≥280 mL/(min·m2) and the 90-day postoperative mortality of ATAAD patients. Methods: The clinical data of 178 ATAAD patients who underwent Sun's procedure in our center from January 2018 to July 2022 were retrospectively analyzed in the present cohort study. The included patients were divided into hypoxic group [DO2 <280 mL/(min·m2)] and normoxic group [DO2 ≥280 mL/(min·m2)]. The primary endpoint was the 90-day all-cause mortality, and the secondary endpoints were postoperative mechanical ventilation time, the application of continuous renal replacement therapy (CRRT), brain complications, and other postoperative complications. Results: Among all the patients, a total of 23 patients died 90 days postoperatively. Compared with the hypoxic group, blood flow, hematocrit (HCT), DO2, and DO2/VO2 ratio during cardiopulmonary bypass (CPB) were significantly higher, while the need for CRRT and the 90-day mortality were significantly lower in the normoxic group. The median follow-up time was 4 months. Kaplan-Meier curve indicated that the survival rate of ATAAD patients in the normoxic group was significantly higher. Univariate cox regression analysis demonstrated that 90-day mortality was reduced by 72.1% in the normoxic group. Conclusions: Maintaining DO2 ≥280 mL/(min·m2) during CPB by increasing CPB flow and HCT level is associated with decreased 90-day mortality of ATAAD patients.

Macrophage polarization states in atherosclerosis.

Atherosclerosis, a chronic inflammatory condition primarily affecting large and medium arteries, is the main cause of cardiovascular diseases. Macrophages are key mediators of inflammatory responses. They are involved in all stages of atherosclerosis development and progression, from plaque formation to transition into vulnerable plaques, and are considered important therapeutic targets. Increasing evidence suggests that the modulation of macrophage polarization can effectively control the progression of atherosclerosis. Herein, we explore the role of macrophage polarization in the progression of atherosclerosis and summarize emerging therapies for the regulation of macrophage polarization. Thus, the aim is to inspire new avenues of research in disease mechanisms and clinical prevention and treatment of atherosclerosis.

The application of del Nido cardioplegia for myocardial protection in adult coronary artery bypass grafting: a cohort study.

BACKGROUND: Del Nido cardioplegia is widely used in adult cardiopulmonary bypass surgery and has a satisfying cardioprotective effect for about 90 minutes by single dose, but the effect in patients with coronary heart disease remains confused. The purpose of this study was to examine the cardioprotective effect of del Nido cardioplegia in adult multivessel coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). METHODS: This retrospective comparative analysis included 124 consecutive patients undergoing isolated on-pump CABG performed by a single surgeon between January 2017 and December 2020. The demographic characteristics and medical history of the included patients were collected. The included patients were divided into two groups: a del Nido cardioplegia (DN) group and a conventional multidose blood cardioplegia (BC) group. Perioperative, intraoperative, and postoperative indicators and complications were compared. RESULTS: Compared with the BC group, CPB and aortic cross-clamp time were significantly shorter in the DN group. In the early postoperative period, the hemoglobin concentration in the DN group was significantly higher than that in the BC group (P<0.05). CONCLUSIONS: This study demonstrated that the application of del Nido cardioplegia in adult on-pump CABG could lead to a significantly shorter aortic cross-clamp and CPB time, as well as a higher hemoglobin concentration in the early postoperative period. The myocardial protective effect of del Nido cardioplegia is not inferior to that of conventional blood perfusion in adult on-pump CABG.

A Novel Rat Model of Cardiac Donation After Circulatory Death Combined With Normothermic ex situ Heart Perfusion.

Background: In heart transplantation, the adoption of hearts from donation after circulatory death (DCD) is considered to be a promising approach to expanding the donor pool. Normothermic ex situ heart perfusion (ESHP) is emerging as a novel preservation strategy for DCD hearts. Therefore, pre-clinical animal models of ESHP are essential to address some key issues before efficient clinical translation. We aim to develop a novel, reproducible, and economical rat model of DCD protocol combined with normothermic ESHP. Methods: Circulatory death of the anesthetized rats in the DCD group was declared when systolic blood pressure below 30 mmHg or asystole was observed after asphyxiation. Additional 15 min of standoff period was allowed to elapse. After perfusion of cold cardioplegia, the DCD hearts were excised and perfused with allogenic blood-based perfusate at constant flow for 90 min in the normothermic ESHP system. Functional assessment and blood gas analysis were performed every 30 min during ESHP. The alteration of DCD hearts submitted to different durations of ESHP (30, 60, and 90 min) in oxidative stress, apoptosis, tissue energy state, inflammatory response, histopathology, cell swelling, and myocardial infarction during ESHP was evaluated. Rats in the non-DCD group were treated similarly but not exposed to warm ischemia and preserved by the normothermic ESHP system for 90 min. Results: The DCD hearts showed compromised function at the beginning of ESHP and recovered over time, while non-DCD hearts presented better cardiac function during ESHP. The alteration of DCD hearts in oxidative stress, apoptosis, tissue energy state, histopathological changes, cell swelling, and inflammatory response didn't differ among different durations of ESHP. At the end of 90-min ESHP, DCD, and non-DCD hearts presented similarly in apoptosis, oxidative stress, inflammatory response, myocardial infarction, and histopathological changes. Moreover, the DCD hearts had lower energy storage and more evident cell swelling compared to the non-DCD hearts. Conclusion: We established a reproducible, clinically relevant, and economical rat model of DCD protocol combined with normothermic ESHP, where the DCD hearts can maintain a stable state during 90-min ESHP.

Application of Mesenchymal Stem Cells During Machine Perfusion: An Emerging Novel Strategy for Organ Preservation.

Although solid organ transplantation remains the definitive management for patients with end-stage organ failure, this ultimate treatment has been limited by the number of acceptable donor organs. Therefore, efforts have been made to expand the donor pool by utilizing marginal organs from donation after circulatory death or extended criteria donors. However, marginal organs are susceptible to ischemia-reperfusion injury (IRI) and entail higher requirements for organ preservation. Recently, machine perfusion has emerged as a novel preservation strategy for marginal grafts. This technique continually perfuses the organs to mimic the physiologic condition, allows the evaluation of pretransplant graft function, and more excitingly facilitates organ reconditioning during perfusion with pharmacological, gene, and stem cell therapy. As mesenchymal stem cells (MSCs) have anti-oxidative, immunomodulatory, and regenerative properties, mounting studies have demonstrated the therapeutic effects of MSCs on organ IRI and solid organ transplantation. Therefore, MSCs are promising candidates for organ reconditioning during machine perfusion. This review provides an overview of the application of MSCs combined with machine perfusion for lung, kidney, liver, and heart preservation and reconditioning. Promising preclinical results highlight the potential clinical translation of this innovative strategy to improve the quality of marginal grafts.