Oxidized Phospholipids Research Articles

Abstract 4130641: The Role of Oxidized Phospholipids in Triggering Trained Immunity and Accelerating Atherosclerotic Plaque Inflammation during Cholesterol Cycling

Introduction: Oxidized phospholipids (OxPL) derived from LDL play a crucial role in the development and progression of atherosclerosis by promoting chronic inflammation and formation of foam cells. The natural antibody E06, binding to OxPL, diminishes macrophage uptake of OxLDL in vitro and decreases atherosclerosis progression in vivo. In our prior work using a model of plasma cholesterol cycling (high-low-high), resulting in atherosclerotic plaque Progression (P)-Regression (PR)-re-Progression (PRP), respectively, we observed accelerated plaque inflammation in the PRP group relative to mice with non-cycling high cholesterol. Hypothesis: OxPL promotes plaque inflammation in the cholesterol cycling model via trained immunity and that the E06 antibody will mitigate this process. Methods: We utilized transgenic "E06 mice" that expressed a single-chain variable fragment of E06 (E06-scFv) using the Apoe promoter on the Ldlr−/− background. Both E06 mice and Ldlr-/- mice were subjected to high cholesterol diets (HCD) and categorized into three groups in the cholesterol cycling model: Baseline Progression (P), PR and PRP. Plaque regression was induced by ApoB-ASO injection, which significantly lowered cholesterol levels by inhibiting LDL production. Results: As before, Ldlr-/- mice in the PRP group exhibited accelerated plaque inflammation post-regression shown by CD68 staining on aortic roots. Notably, this acceleration was significantly inhibited in the E06 mice, highlighting the protective effects of E06 against plaque re-progression. Additionally, flow cytometry of peripheral blood exhibited reduced total monocytes and Ly6Chi-monocytes (thought to become inflammatory macrophages in plaques), alongside increased Ly6Clo-monocytes (thought to become inflammation resolving macrophages in plaques) among E06 mice in the PRP group compared to Ldlr-/- mice. Ex-vivo stimulation of bone marrow cells with the inflammatory stimulus LPS demonstrated higher IL-6 levels in supernatant in Ldlr-/- mice versus E06 mice in the PRP group, suggesting OXPL-induced trained immunity in bone marrow precursors of monocytes and macrophages is involved. Conclusion: The acceleration of plaque inflammation in cholesterol cycling model was significantly inhibited in the E06 mice. These results provide insight into the increased risk of cardiovascular disease in individuals with intermittent adherence to statins who undergo cholesterol cycling.

Abstract 4119560: Oxidized Phospholipids and Calcific Aortic Valvular Disease

Introduction: Oxidized phospholipids (OxPL) are carried by apolipoprotein B-100-containing lipoproteins (OxPL-apoB) including lipoprotein(a) [Lp(a)]. Both OxPL-apoB and Lp(a) have been associated with calcific aortic valve disease (CAVD). Aims: We aimed to evaluate the independent associations between OxPL-apoB, Lp(a) and the prevalence, incidence, and progression of CAVD. Methods: OxPL-apoB and Lp(a) were evaluated in the Multi-Ethnic Study of Atherosclerosis (MESA) and a participant-level meta-analysis of four randomized trials of participants with established aortic stenosis (AS). In MESA, the association of OxPL-apoB and Lp(a) with aortic valve calcium (AVC) at baseline and 9.5 years was evaluated using multivariable ordinal regression models. In the meta-analysis, the association between OxPL-apoB and Lp(a) with AS progression (annualized change in peak aortic valve jet velocity (V max )) was evaluated using multivariable linear regression models. Results: In MESA, both OxPL-apoB and Lp(a) were independently associated with prevalent AVC (OR (95% CI) per SD: 1.19 (1.07-1.32) and 1.13 (1.01-1.27), respectively) with a significant interaction between the two (p<0.01). Both OxPL-apoB and Lp(a) were associated with incident AVC at 9.5 years when evaluated independently (interaction p<0.01). The OxPL-apoB*Lp(a) interaction demonstrated higher odds of prevalent and incident AVC for OxPL-apoB with increasing Lp(a) levels. Mediation analyses demonstrated that Lp(a) partially mediated the association between OxPL-apoB and AVC. In a 2x2 analysis, the greatest risk for both prevalent and incident AVC was observed when Lp(a) and OxPL-apoB were both above the 80 th percentile ( Figure ). In the meta-analysis, when analyzed separately, both OxPL-apoB and Lp(a) were independently associated with faster increase in V max , but when evaluated together, only OxPL-apoB remained significant (ß 0.07, 95% CI 0.01-0.12, Figure ). Conclusions: OxPL-apoB is an independent predictor of the presence, incidence and progression of AVC and established AS, particularly in the setting of elevated Lp(a) levels and may represent a novel therapeutic target for CAVD.

Evaluation of IL 12 gene expression and serum levels of OxPL / apoB in patients with coronary artery disease

Background: Atherosclerotic lesions are formed as a result of low-density lipoprotein (LDL) accumulation, which is produced by oxidizing enzymes and oxidized phospholipids (OxPL). Phospholipid oxide causes inflammation-inducing activation genes and hyper-inflammation in addition to the initiation of inflammation and expression of Th1 cytokines. Interleukin 12 (IL-12) is one of the most significant stimulants of inflammation and immune responses, among the Th1cytokines. Therefore, it may play a significant role in contributing to atherosclerosis. The quantitative expression of IL-12 mRNA, along with serum OxPL levels, has been analyzed in patients with coronary artery disease (CAD). Methods: Coronary angiography patients, aged 45 to 65 years and referred with chest pain, were examined. The patients were classified into normal coronary arteries (N = 38) and severe three-vessel involvement coronary arteries (N = 41). Molecular testing was performed using real-time PCR. Also, an ELISA test was used to check the OxPl level. Results: Expression of IL12 in Individuals with coronary artery disease was increased but was not statistically significant.

Oxidized Phospholipids and CalcificAortic Valvular Disease.

Oxidized phospholipids (OxPLs) are carried by apolipoprotein B-100-containing lipoproteins (OxPL-apoB) including lipoprotein(a) (Lp[a]). Both OxPL-apoB and Lp(a) have been associated with calcific aortic valve disease (CAVD). This study aimed to evaluate the associations between OxPL-apoB, Lp(a) and the prevalence, incidence, and progression of CAVD. OxPL-apoB and Lp(a) were evaluated in MESA (Multi-Ethnic Study of Atherosclerosis) and a participant-level meta-analysis of 4 randomized trials of participants with established aortic stenosis (AS). In MESA, the association of OxPL-apoB and Lp(a) with aortic valve calcium (AVC) at baseline and 9.5 years was evaluated using multivariable ordinal regression models. In the meta-analysis, the association between OxPL-apoB and Lp(a) with AS progression (annualized change in peak aortic valve jet velocity) was evaluated using multivariable linear regression models. In MESA, both OxPL-apoB and Lp(a) were associated with prevalent AVC (OR per SD: 1.19 [95% CI: 1.07-1.32] and 1.13 [95% CI: 1.01-1.27], respectively) with a significant interaction between the two (P< 0.01). Both OxPL-apoB and Lp(a) were associated with incident AVC at 9.5 years when evaluated individually (interaction P< 0.01). The OxPL-apoB∗Lp(a) interaction demonstrated higher odds of prevalent and incident AVC for OxPL-apoB with increasing Lp(a) levels. In the meta-analysis, when analyzed separately, both OxPL-apoB and Lp(a) were associated with faster increase inpeak aortic valve jet velocity, but when evaluated together, only OxPL-apoB remained significant (ß: 0.07; 95%CI: 0.01-0.12). OxPL-apoB is a predictor of the presence, incidence, and progression of AVC and established AS, particularly in the setting of elevated Lp(a) levels, and may represent a novel therapeutic target for CAVD.

Changes and significance of oxidized phospholipids and endothelial nitric oxide synthase in the acute stage of Kawasaki disease

To investigate the changes in the serum levels of oxidized phospholipids (OxPLs) and endothelial nitric oxide synthase (eNOS) and their association with coronary artery disease (CAL) in children in the acute stage of Kawasaki disease (KD), as well as the clinical significance of OxPLs and eNOS. A prospective study was conducted on 95 children in the acute stage of KD (KD group). According to the presence of absence of CAL, the KD group was further divided into a CAL subgroup and a non-CAL (NCAL) subgroup. Thirty children with fever due to lower respiratory tract infection were enrolled as the fever group. Thirty healthy children who underwent physical examination were enrolled as the healthy control group. The above groups were compared in terms of general information and serum levels of OxPLs, eNOS and other laboratory indexes, and the correlation between OxPLs level and eNOS level was analyzed. The KD group had a significantly higher level of OxPLs and a significantly lower level of eNOS compared with the fever group and the healthy control group (P<0.05). After treatment, the children with KD had a significantly decreased OxPLs level and a significantly increased eNOS level (P<0.05). Compared with the NCAL subgroup, the CAL subgroup had a significantly higher level of OxPLs and a significantly lower level of eNOS (P<0.05). Among the children of KD, the level of OxPLs was negatively correlated with that of eNOS (rs=-0.353, P<0.05). Serum OxPLs and eNOS in the acute stage of KD may be involved in the development of CAL in children with KD, and therefore, they may be used as the biomarkers to predict CAL in these children.

Associations between lipoprotein(a), oxidized phospholipids, and extracoronary vascular disease

The roles of lipoprotein(a) [Lp(a)] and related oxidized phospholipids (OxPLs) in the development and progression of coronary disease is known, but their influence on extracoronary vascular disease is not well-established. We sought to evaluate associations between Lp(a), OxPL apolipoprotein B (OxPL-apoB), and apolipoprotein(a) (OxPL-apo(a)) with angiographic extracoronary vascular disease and incident major adverse limb events (MALEs). Four hundred forty-six participants who underwent coronary and/or peripheral angiography were followed up for a median of 3.7 years. Lp(a) and OxPLs were measured before angiography. Elevated Lp(a) was defined as ≥150 nmol/L. Elevated OxPL-apoB and OxPL-apo(a) were defined as greater than or equal to the 75th percentile (OxPL-apoB ≥8.2 nmol/L and OxPL-apo(a) ≥35.8 nmol/L, respectively). Elevated Lp(a) had a stronger association with the presence of extracoronary vascular disease compared to OxPLs and was minimally improved with the addition of OxPLs in multivariable models. Compared to participants with normal Lp(a) and OxPL concentrations, participants with elevated Lp(a) levels were twice as likely to experience a MALE (odds ratio: 2.14, 95% confidence interval: 1.03, 4.44), and the strength of the association as well as the C statistic of 0.82 was largely unchanged with the addition of OxPL-apoB and OxPL-apo(a). Elevated Lp(a) and OxPLs are risk factors for progression and complications of extracoronary vascular disease. However, the addition of OxPLs to Lp(a) does not provide additional information about risk of extracoronary vascular disease. Therefore, Lp(a) alone captures the risk profile of Lp(a), OxPL-apoB, and OxPL-apo(a) in the development and progression of atherosclerotic plaque in peripheral arteries.

Elovanoids Suppress Lipid Peroxidation after Experimental Stroke: An LC-MS-based Untargeted Lipidomics Analysis

At the onset and progression of neurodegenerative diseases, enhanced reactive oxygen species (ROS) and an overall uncompensated oxidative stress environment evolve. Oxidized phospholipids (OxPLs) cause detrimental perturbations to synaptic membranes and other parts of the nervous system. We tested if the lipid mediators Elovanoids (ELVs) that exert neuroprotective signaling also counteract lipid peroxidation using an experimental ischemic stroke model. Male Sprague-Dawley rats after 2 hours of middle cerebral artery occlusion (MCAo) were used. ELV-N34 was administered intranasally at 1 hour, 24 hours and 48 hours after, and rats were sacrificed on day 3; the brains were removed and sampled into the right and left hemispheres and the cortex, subcortex. Untargeted lipidomics were performed using a Waters Xevo G2-XS QTof system under MSE mode, and collected MS/MS spectra for the OxPLs was processed and searched against a reference spectral library by MS-DIAL software. ELV-N34 reduced oxidized phosphatidylcholine (OxPC) and phosphatidylethanolamine (OxPE) molecular species. We suggest that ELVs target lipid peroxidation as part of their neuroprotective bioactivity.

Elovanoid Precursor Inhibits Lipid Peroxidation in Retinal Cells: A Comprehensive Untargeted Lipidomic Approach

Age-related macular degeneration (AMD) accumulates amyloid-beta peptide as in senile plaques of Alzheimer's. Also, as in other neurodegenerative diseases, enhanced reactive oxygen species (ROS) and an overall uncompensated oxidative stress (UOS) environment evolve. Oxidized phospholipids (OxPLs) cause detrimental perturbations to photoreceptor cells (PRC) and to the retinal pigment epithelial cell (RPEC), a nondividing cell derived from the neuroectoderm, essential for PRC integrity. Elovanoids (ELVs) are lipid mediators that support PRC. They are oxygenated derivatives of very long-chain polyunsaturated fatty acids (VLC-PUFAs), specifically C32:6 and C34:6. PUFA-containing phospholipids in the cell membrane are susceptible to non-enzymatic (e.g., free radical and reactive oxygen species) and enzymatic oxidation of the unsaturated components, altering their structure and function. Studies have implicated oxidized phospholipids as relevant to the etiology of aging and neurodegeneration, including age-related macular degeneration and Alzheimer's. Due to high metabolic demands, RPE cells are under constant oxidative stress.

Abstract 17748: Lipoprotein(a) and Oxidized Phospholipids on Lipoproteins and Cardiovascular Outcomes in Patients With Chronic Coronary Syndrome Treated With Colchicine

Introduction: Lipoproteins carrying pro-inflammatory oxidized phospholipids (OxPL), exemplified by lipoprotein(a) [Lp(a)], contribute to residual risk for major adverse cardiovascular events (MACE) in patients with chronic coronary syndrome (CCS) despite optimal medical treatment. Hypothesis: Anti-inflammatory colchicine therapy modifies MACE in patients with elevated Lp(a), OxPL on apo(a) [OxPL-apo(a)], and OxPL on apoB containing lipoproteins (OxPL-apoB). Aims To study the relationship of Lp(a), OxPL-apo(a) and OxPL-apoB with MACE in 1777 LoDoCo2 trial participants with CCS randomized to colchicine or placebo. Methods: End of study but not baseline samples were available. Because Lp(a), OxPL-apo(a) and OxPL-apoB levels are strongly genetically determined, we assumed that end of study values would reflect baseline values. The primary endpoint was a composite of MI, ischemic CVA or ischemia driven coronary revascularization. Cox regression was used to compare the incidence of the primary endpoint by Lp(a) dichotomized at 125 nmol/L and OxPL-apo(a) and OxPL-apoB in tertiles. Results: At study end, median (IQR) on-colchicine Lp(a), OxPL-apo(a), and OxPL-apoB levels in nmol/L were 22.4 (7.2-102.7), 7.8 (2.0-34.5) and 3.1 (1.3-6.3), similar to on-placebo levels of 23.9 (9.9-95.7), 8.8 (2.7-34.0), and 3.1 (1.4-5.9), respectively (p = 0.20, 0.98 and 0.18). MACE reduction with colchicine was independent of Lp(a) and OxPL-apo(a) (P interaction = 0.92 and 0.66 respectively). However, the largest MACE reduction was present in the highest vs lowest OxPL-apoB tertile ( Figure , P interaction &lt; 0.05). Conclusions: The benefit of colchicine in reducing MACE was highest in subjects with elevated OxPL-apoB, suggesting colchicine may be most effective in subjects with heightened oxidation-driven inflammation. These findings may be hypothesis-generating and require validation in larger trials with baseline biomarker assessment including CRP and IL-6.

Oxidized phospholipids in cardiovascular disease.

Prolonged or excessive exposure to oxidized phospholipids (OxPLs) generates chronic inflammation. OxPLs are present in atherosclerotic lesions and can be detected in plasma on apolipoprotein B (apoB)-containing lipoproteins. When initially conceptualized, OxPL-apoB measurement in plasma was expected to reflect the concentration of minimally oxidized LDL, but, surprisingly, it correlated more strongly with plasma lipoprotein(a) (Lp(a)) levels. Indeed, experimental and clinical studies show that Lp(a) particles carry the largest fraction of OxPLs among apoB-containing lipoproteins. Plasma OxPL-apoB levels provide diagnostic information on the presence and extent of atherosclerosis and improve the prognostication of peripheral artery disease and first and recurrent myocardial infarction and stroke. The addition of OxPL-apoB measurements to traditional cardiovascular risk factors improves risk reclassification, particularly in patients in intermediate risk categories, for whom improving decision-making is most impactful. Moreover, plasma OxPL-apoB levels predict cardiovascular events with similar or greater accuracy than plasma Lp(a) levels, probably because this measurement reflects both the genetics of elevated Lp(a) levels and the generalized or localized oxidation that modifies apoB-containing lipoproteins and leads to inflammation. Plasma OxPL-apoB levels are reduced by Lp(a)-lowering therapy with antisense oligonucleotides and by lipoprotein apheresis, niacin therapy and bariatric surgery. In this Review, we discuss the role of role OxPLs in the pathophysiology of atherosclerosis and Lp(a) atherogenicity, and the use of OxPL-apoB measurement for improving prognosis, risk reclassification and therapeutic interventions.

Lipoprotein(a)-60 Years Later-What Do We Know?

Lipoprotein(a) (Lp(a)) molecule includes two protein components: apolipoprotein(a) and apoB100. The molecule is the main transporter of oxidized phospholipids (OxPL) in plasma. The concentration of this strongly atherogenic lipoprotein is predominantly regulated by the LPA gene expression. Lp(a) is regarded as a risk factor for several cardiovascular diseases. Numerous epidemiological, clinical and in vitro studies showed a strong association between increased Lp(a) and atherosclerotic cardiovascular disease (ASCVD), calcific aortic valve disease/aortic stenosis (CAVD/AS), stroke, heart failure or peripheral arterial disease (PAD). Although there are acknowledged contributions of Lp(a) to the mentioned diseases, clinicians struggle with many inconveniences such as a lack of well-established treatment lowering Lp(a), and common guidelines for diagnosing or assessing cardiovascular risk among both adult and pediatric patients. Lp(a) levels are different with regard to a particular race or ethnicity and might fluctuate during childhood. Furthermore, the lack of standardization of assays is an additional impediment. The review presents the recent knowledge on Lp(a) based on clinical and scientific research, but also highlights relevant aspects of future study directions that would approach more suitable and effective managing risk associated with increased Lp(a), as well as control the Lp(a) levels.

Oxidized phospholipids facilitate calcific aortic valve disease by elevating ATF4 through the PERK/eIF2α axis.

In this study we sought to analyze the critical role of oxidized phospholipid (OxPL) in the progression of calcific aortic valve disease (CAVD) with the involvement of activating transcription factor 4 (ATF4). Differentially expressed genes related to CAVD were identified using bioinformatics analysis. Expression of ATF4 was examined in mouse models of aortic valve calcification (AVC) induced by the high cholesterol (HC) diet. Valvular interstitial cells (VICs) were then isolated from mouse non-calcified valve tissues, induced by osteogenic induction medium (OIM) and co-cultured with OxPAPC-stimulated macrophages. The effect of OxPLs regulating ATF4 on the macrophage polarization and osteogenic differentiation of VICs was examined with gain- and loss-of-function experiments in VICs and in vivo. In aortic valve tissues and OIM-induced VICs, ATF4 was highly expressed. ATF4 knockdown alleviated the osteogenic differentiation of VICs, as evidenced by reduced expression of bone morphogenetic protein-2 (BMP2), osteopontin (OPN), and osteocalcin. In addition, knockdown of ATF4 arrested the AVC in vivo. Meanwhile, OxPL promoted M1 polarization of macrophages and mediated osteogenic differentiation of VICs. Furthermore, OxPL up-regulated ATF4 expression through protein kinase R-like endoplasmic reticulum kinase (PERK)/eukaryotic translation initiation factor 2 subunit alpha (eIF2α) pathway. In conclusion, OxPL can potentially up-regulate the expression of ATF4, inducing macrophages polarized to M1 phenotype, osteogenic differentiation of VICs and AVC, thus accelerating the progression of CAVD.

Truncated oxidized phospholipids exacerbate endothelial dysfunction and lung injury caused by bacterial pathogens

Oxidized phospholipids (OxPLs) are present at basal levels in circulation of healthy individuals, but a substantial increase and changes in composition of OxPLs may rapidly occur during microbial infections, sepsis, and trauma. Specifically, truncated oxidized phospholipids (Tr-OxPLs) exhibit detrimental effects on pulmonary endothelium, yet their role on modulation of lung injury caused by bacterial pathogens remains to be elucidated. This study investigated the effects of Tr-OxPL species: KOdiA-PC, POV-PC, PON-PC, PAz-PC, PGPC, and Lyso-PC on endothelial permeability and inflammatory responses to gram-positive bacterial particles. Results showed that all six tested Tr-OxPLs augmented endothelial barrier disruption caused by heat-killed Staphylococcus aureus (HKSA) as determined by VE-cadherin immunostaining and monitoring transendothelial electrical resistance. In parallel, even moderate elevation of Tr-OxPLs augmented HKSA-induced activation of NF-κB, secretion of IL-6 and IL-8, and protein expression of ICAM-1 and VCAM-1. In the mouse model of acute lung injury caused by intranasal injection of HKSA, intravenous Tr-OxPLs administration augmented HKSA-induced increase in BAL protein content and cell counts, tissue expression of TNFα, KC, IL1β, and CCL2, and promoted vascular leak monitored by lung infiltration of Evans Blue. These results suggest that elevated Tr-OxPLs act as critical risk factor worsening bacterial pathogen-induced endothelial dysfunction and lung injury.

On-treatment platelet reactivity through the thromboxane A2 or P2Y12 platelet receptor pathways is not affected by pelacarsen.

Pelacarsen decreases plasma levels of lipoprotein(a) [Lp(a)] and oxidized phospholipids (OxPL). It was previously reported that pelacarsen does not affect the platelet count. We now report the effect of pelacarsen on on-treatment platelet reactivity. Subjects with established cardiovascular disease and screening Lp(a) levels ≥60mg per deciliter (~ ≥150 nmol/L) were randomized to receive pelacarsen (20, 40, or 60mg every 4 weeks; 20mg every 2 weeks; or 20mg every week), or placebo for 6-12 months. Aspirin Reaction Units (ARU) and P2Y12 Reaction Units (PRU) were measured at baseline and the primary analysis timepoint (PAT) at 6 months. Of the 286 subjects randomized, 275 had either an ARU or PRU test, 159 (57.8%) were on aspirin alone and 94 (34.2%) subjects were on dual anti-platelet therapy. As expected, the baseline ARU and PRU were suppressed in subjects on aspirin or on dual anti-platelet therapy, respectively. There were no significant differences in baseline ARU in the aspirin groups or in PRU in the dual anti-platelet groups. At the PAT there were no statistically significant differences in ARU in subjects on aspirin or PRU in subjects on dual anti-platelet therapy among any of the pelacarsen groups compared to the pooled placebo group (p > 0.05 for all comparisons). Pelacarsen does not modify on-treatment platelet reactivity through the thromboxane A2 or P2Y12 platelet receptor pathways.

High levels of lipoprotein(a) in transgenic mice exacerbate atherosclerosis and promote vulnerable plaque features in a sex-specific manner

Background and aimsDespite increased clinical interest in lipoprotein(a) (Lp(a)), many questions remain about the molecular mechanisms by which it contributes to atherosclerotic cardiovascular disease. Existing murine transgenic (Tg) Lp(a) models are limited by low plasma levels of Lp(a) and have not consistently shown a pro-atherosclerotic effect of Lp(a). MethodsWe generated Tg mice expressing both human apolipoprotein(a) (apo(a)) and human apoB-100, with pathogenic levels of plasma Lp(a) (range 87–250 mg/dL). Female and male Lp(a) Tg mice (Tg(LPA+/0;APOB+/0)) and human apoB-100-only controls (Tg(APOB+/0)) (n = 10–13/group) were fed a high-fat, high-cholesterol diet for 12 weeks, with Ldlr knocked down using an antisense oligonucleotide. FPLC was used to characterize plasma lipoprotein profiles. Plaque area and necrotic core size were quantified and immunohistochemical assessment of lesions using a variety of cellular and protein markers was performed. ResultsMale and female Tg(LPA+/0;APOB+/0) and Tg(APOB+/0) mice exhibited proatherogenic lipoprotein profiles with increased cholesterol-rich VLDL and LDL-sized particles and no difference in plasma total cholesterol between genotypes. Complex lesions developed in the aortic sinus of all mice. Plaque area (+22%), necrotic core size (+25%), and calcified area (+65%) were all significantly increased in female Tg(LPA+/0;APOB+/0) mice compared to female Tg(APOB+/0) mice. Immunohistochemistry of lesions demonstrated that apo(a) deposited in a similar pattern as apoB-100 in Tg(LPA+/0;APOB+/0) mice. Furthermore, female Tg(LPA+/0;APOB+/0) mice exhibited less organized collagen deposition as well as 42% higher staining for oxidized phospholipids (OxPL) compared to female Tg(APOB+/0) mice. Tg(LPA+/0;APOB+/0) mice had dramatically higher levels of plasma OxPL-apo(a) and OxPL-apoB compared to Tg(APOB+/0) mice, and female Tg(LPA+/0;APOB+/0) mice had higher plasma levels of the proinflammatory cytokine MCP-1 (+3.1-fold) compared to female Tg(APOB+/0) mice. ConclusionsThese data suggest a pro-inflammatory phenotype exhibited by female Tg mice expressing Lp(a) that appears to contribute to the development of more severe lesions with greater vulnerable features.

Lipoprotein(a), Oxidized Phospholipids, and Coronary Artery Disease Severity and Outcomes

BackgroundLipoprotein(a) (Lp[a]) and oxidized phospholipids (OxPLs) are each independent risk factors for atherosclerotic cardiovascular disease. The extent to which Lp(a) and OxPLs predict coronary artery disease (CAD) severity and outcomes in a contemporary, statin-treated cohort is not well established. ObjectivesThis study sought to evaluate the relationships between Lp(a) particle concentration and OxPLs associated with apolipoprotein B (OxPL-apoB) or apolipoprotein(a) (OxPL-apo[a]) with angiographic CAD and cardiovascular outcomes. MethodsAmong 1,098 participants referred for coronary angiography in the CASABLANCA (Catheter Sampled Blood Archive in Cardiovascular Diseases) study, Lp(a), OxPL-apoB, and OxPL-apo(a) were measured. Logistic regression estimated the risk of multivessel coronary stenoses by Lp(a)-related biomarker level. Cox proportional hazards regression estimated the risk of major adverse cardiovascular events (MACEs) (coronary revascularization, nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death) in follow-up. ResultsMedian Lp(a) was 26.45 nmol/L (IQR: 11.39-89.49 nmol/L). Lp(a), OxPL-apoB, and OxPL-apo(a) were highly correlated (Spearman R ≥0.91 for all pairwise combinations). Lp(a) and OxPL-apoB were associated with multivessel CAD. Odds of multivessel CAD per doubling of Lp(a), OxPL-apoB, and OxPL-apo(a) were 1.10 (95% CI: 1.03-1.18; P = 0.006), 1.18 (95% CI: 1.03-1.34; P = 0.01), and 1.07 (95% CI: 0.99-1.16; P = 0.07), respectively. All biomarkers were associated with cardiovascular events. HRs for MACE per doubling of Lp(a), OxPL-apoB, and OxPL-apo(a) were 1.08 (95% CI: 1.03-1.14; P = 0.001), 1.15 (95% CI: 1.05-1.26; P = 0.004), and 1.07 (95% CI: 1.01-1.14; P = 0.02), respectively. ConclusionsIn patients undergoing coronary angiography, Lp(a) and OxPL-apoB are associated with multivessel CAD. Lp(a), OxPL-apoB, and OxPL-apo(a) are associated with incident cardiovascular events. (Catheter Sampled Blood Archive in Cardiovascular Diseases [CASABLANCA]; NCT00842868)

Role of enterocyte Enpp2 and autotaxin in regulating lipopolysaccharide levels, systemic inflammation, and atherosclerosis

Conversion of lysophosphatidylcholine to lysophosphatidic acid (LPA) by autotaxin, a secreted phospholipase D, is a major pathway for producing LPA. We previously reported that feeding Ldlr−/− mice standard mouse chow supplemented with unsaturated LPA or lysophosphatidylcholine qualitatively mimicked the dyslipidemia and atherosclerosis induced by feeding a Western diet (WD). Here, we report that adding unsaturated LPA to standard mouse chow also increased the content of reactive oxygen species and oxidized phospholipids (OxPLs) in jejunum mucus. To determine the role of intestinal autotaxin, enterocyte-specific Ldlr−/−/Enpp2 KO (intestinal KO) mice were generated. In control mice, the WD increased enterocyte Enpp2 expression and raised autotaxin levels. Ex vivo, addition of OxPL to jejunum from Ldlr−/− mice on a chow diet induced expression of Enpp2. In control mice, the WD raised OxPL levels in jejunum mucus and decreased gene expression in enterocytes for a number of peptides and proteins that affect antimicrobial activity. On the WD, the control mice developed elevated levels of lipopolysaccharide in jejunum mucus and plasma, with increased dyslipidemia and increased atherosclerosis. All these changes were reduced in the intestinal KO mice. We conclude that the WD increases the formation of intestinal OxPL, which i) induce enterocyte Enpp2 and autotaxin resulting in higher enterocyte LPA levels; that ii) contribute to the formation of reactive oxygen species that help to maintain the high OxPL levels; iii) decrease intestinal antimicrobial activity; and iv) raise plasma lipopolysaccharide levels that promote systemic inflammation and enhance atherosclerosis.

Lipoprotein(a) in Atherosclerotic Diseases: From Pathophysiology to Diagnosis and Treatment.

Lipoprotein(a) (Lp(a)) is a low-density lipoprotein (LDL) cholesterol-like particle bound to apolipoprotein(a). Increased Lp(a) levels are an independent, heritable causal risk factor for atherosclerotic cardiovascular disease (ASCVD) as they are largely determined by variations in the Lp(a) gene (LPA) locus encoding apo(a). Lp(a) is the preferential lipoprotein carrier for oxidized phospholipids (OxPL), and its role adversely affects vascular inflammation, atherosclerotic lesions, endothelial function and thrombogenicity, which pathophysiologically leads to cardiovascular (CV) events. Despite this crucial role of Lp(a), its measurement lacks a globally unified method, and, between different laboratories, results need standardization. Standard antilipidemic therapies, such as statins, fibrates and ezetimibe, have a mediocre effect on Lp(a) levels, although it is not yet clear whether such treatments can affect CV events and prognosis. This narrative review aims to summarize knowledge regarding the mechanisms mediating the effect of Lp(a) on inflammation, atherosclerosis and thrombosis and discuss current diagnostic and therapeutic potentials.

Abstract 9381: Lipoprotein(a), Oxidized Phospholipids, and Coronary Artery Disease Severity and Outcomes

Introduction: Lipoprotein(a) [Lp(a)] and related oxidized phospholipids (OxPLs) are independent risk factors for atherosclerotic cardiovascular disease. The extent to which Lp(a) and OxPLs together predict coronary artery disease (CAD) severity and outcomes is unclear. We measured Lp(a) isoform-independent particle number and OxPLs associated with apolipoprotein(a) [OxPL-apo(a)] and apolipoprotein-B (OxPL-apoB) among participants in CASABLANCA (ClinicalTrials.gov NCT00842868), a contemporary cath-based registry, and assessed angiographic CAD at baseline and CV events in follow-up. Methods: In 1098 participants undergoing baseline coronary angiography, logistic regression estimated odds of any CAD (≥1 severe coronary stenosis) or multi-vessel CAD (≥2 severe coronary stenoses). Cox proportional hazards regression estimated risk of major adverse cardiovascular events (MACE: non-fatal MI, non-fatal stroke, CV death, or coronary revascularization) over median 4.2 years. Models were adjusted for age, sex, medical history, cholesterol, smoking, and statin use. Results: Median [IQR] Lp(a) was 26.45 nmol/L [11.39-89.49]. Lp(a), OxPL-apoB, and OxPL-apo(a) were highly correlated (Spearman R≥0.91 for all pairwise combinations). Biomarkers were not associated with any CAD, but Lp(a) and OxPL-apoB were associated with multi-vessel CAD. All biomarkers were associated with CV events. Odds of multi-vessel CAD per doubling of Lp(a), OxPL-apoB, and OxPL-apo(a) were 1.10 (95% CI 1.03-1.18, P=0.006), 1.18 (95% CI 1.03-1.34, P=0.01), and 1.07 (95% CI 0.99-1.16, P=0.07), respectively ( Figure, A ). Hazard ratios for MACE per doubling of Lp(a), OxPL-apoB, and OxPL-apo(a) were 1.08 (95% CI 1.03-1.14, P=0.001), 1.15 (95% CI 1.05-1.26, P=0.004), and 1.07 (95% CI 1.01-1.14, P=0.02), respectively ( Figure, B ). Conclusions: Lp(a) and OxPL-apoB are associated with multi-vessel CAD. Lp(a), OxPL-apoB, and OxPL-apo(a) are associated with incident CV events.

Oxidized phospholipids are biomarkers, drug targets, and drug leads

Enzymatic oxidation or autooxidation of esterified polyunsaturated fatty acids (PUFA) residues within phospholipids in cell membranes or circulating lipoprotein particles leads to the formation of a broad range of oxidized phospholipid (OxPL) species. Chronically elevated OxPL levels present in circulation and atherosclerotic plaques are thought to induce proinflammatory and injurious effects on blood- and vessel wall cells. However, analysis of the structure-activity relationship also identified specific OxPL products exhibiting prominent anti-inflammatory, pro-survival and barrier protective properties. This minireview will briefly summarize rapidly accumulating evidence pointing to the importance of OxPLs in pathology, where they can play multiple roles of biomarkers, drug targets and drug leads.