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Lipoprotein(a) integrates monocyte-mediated thrombosis and inflammation in atherosclerotic cardiovascular disease

ABSTRACT: Although therapies for atherosclerotic cardiovascular disease (ASCVD) have advanced, substantial residual risk of cardiovascular (CV) events remains. Lipoprotein (a) [Lp(a)] is a low-density lipoprotein (LDL) particle that is causally linked to both ASCVD and CV events. Lp(a) is thought to drive ASCVD through multiple mechanisms including its effects on cholesterol accumulation, inflammation, and thrombosis. Although the associations between Lp(a) and ASCVD drivers are clear, the mechanisms that integrate Lp(a)-mediated cholesterol accumulation, inflammation, and thrombosis remain largely unknown. In this study, we employed systems biology approaches consisting of proteomics, transcriptomics, and mass cytometry to define the immune cellular and molecular phenotypes in ASCVD subjects with high and low Lp(a) levels and the mechanisms through which Lp(a) mediates monocyte activation. In a cohort of stable ASCVD subjects (n=64 [41 with high Lp(a) and 23 with low Lp(a]), we found that circulating markers of inflammation (CCL28, IL-17D) and vascular dysfunction (BNP), tissue factor [TF]) was elevated in subjects with high Lp(a) levels compared with those with low Lp(a) levels. Additionally, although total monocytes levels and hs-CRP levels were similar between the groups, CD14+ monocytes from ASCVD subjects with an elevated Lp(a) were primed and expressed more TF at baseline and in response to stress. Mechanistically, we found that Lp(a) itself can activate monocytes through Toll-like receptors (TLR) and nuclear factor kappa B (NFκB) signaling, driving both the induction of TF and TF activity. Overall, these studies are the first to link Lp(a) to monocyte-mediated inflammation and thrombosis, demonstrating a novel mechanism through TLR2, NFκB, and monocyte TF which Lp(a) amplifies immunothrombotic risk.

ORGANISM(S): Homo sapiens

PROVIDER: GSE253997 | GEO | 2025/07/16

REPOSITORIES: GEO

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Project description:Background: OxPLs play a key role in the atherogenic potential of Lp(a), however Lp(a) is a complex particle that warrants research into additional pro-inflammatory mediators. We hypothesized that additional Lp(a)-associated lipids contribute to the atherogenicity of Lp(a). Methods: Untargeted lipidomics was performed on plasma and isolated lipoprotein fractions. The atherogenicity of the observed Lp(a)-associated lipids was tested ex vivo in primary human monocytes by RNAseq, ELISA, Western Blot and transendothelial migratory assays. Using immunofluorescence staining and single-cell RNA sequencing, the phenotype of macrophages was investigated in human atherosclerotic lesions. Results: Compared to healthy individuals with low/normal Lp(a) levels [median 7 mg/dL (18 nmol/L); N=13], individuals with elevated Lp(a) levels [median 87 mg/dL (218 nmol/L); N=12] demonstrated an increase in lipid species, particularly diacylglycerols (DGs) and lysophosphatidic acid (LPA). DG and the LPA precursor lysophosphatidylcholine were enriched in the Lp(a) fraction. Ex vivo stimulation with DG(40:6) demonstrated a significant upregulation in pro-inflammatory pathways related to leukocyte migration, chemotaxis, NF-κB signalling and cytokine production. Functional assessment showed a dose-dependent increase in the secretion of IL-6, IL-8 and IL-1β after DG(40:6) and DG(38:4) stimulation, which was in part mediated via the NLRP3-inflammasome. Conversely, LPA-stimulated monocytes did not exhibit an inflammatory phenotype. Furthermore, activation of monocytes by DGs and LPA increased their transendothelial migratory capacity. Human atherosclerotic plaques from patients with high Lp(a) levels demonstrated co-localisation of Lp(a) with M1 macrophages, and an enrichment of CD68+IL18+TLR4+TREM2+ resident macrophages and CD68+CASP1+IL1B+SELL+ inflammatory macrophages compared to patients with low Lp(a). Finally, potent Lp(a) lowering treatment (pelacarsen), resulted in a reduction in specific circulating DG lipid subspecies in cardiovascular disease patients with elevated Lp(a) levels [median 82 mg/dL (205 nmol/L)]. Conclusions: Lp(a)-associated DGs and LPA have a potential role in Lp(a)-induced monocyte inflammation by increasing cytokine secretion and monocyte transendothelial migration. This DG-induced inflammation is in part NLRP3-inflammasome dependent.

Project description:Background. HIV-infected individuals on antiretroviral therapy (HIV/ART) experience higher levels of non-AIDS morbidity than uninfected people, which is believed to be driven by inflammation that persists despite viral suppression. Elevations in plasma cytokines, coagulation markers and both innate and adaptive immune cell activation during untreated infection are often incompletely reversed by ART and associated with these morbidities. Monocytes/macrophages play a central role in many of these complications including neurocognitive and cardiovascular disease. Results. We investigated monocyte surface markers, gene expression and plasma cytokines in 11 HIV-infected older individuals (median age 53 years) who started therapy with low CD4 counts (median 129 cells/ul), with elevated hsCRP (≥2mg/L) despite long-term ART (median 7.4 years), along with age, gender, race and smoking status-matched controls. Major monocyte subsets (based on CD14/CD16/CD163) were not different from controls, but surface levels differed for CD163 (p=0.022), PD1 (p=0.015) and a trend for tissue factor (p=0.098). As a group, HIV/ART subjects had elevated levels of plasma CCL2 (MCP-1; p=0.0001), CXCL9 (MIG; p=0.04) and sIL2R (p=0.015), which were highly correlated, whereas sCD14 and several other markers were not significantly elevated. However, principal component analysis of soluble markers revealed that about half of HIV/ART subjects clustered with controls, whereas the remainder were distinct, driven by IL-10, CCL11, CXCL10, CXCL11 as well as CCL2, CXCL9 and sIL2R. Outlier subjects were significantly older than those who clustered with controls. Gene expression analysis unexpectedly revealed downregulation in HIV/ART monocytes of multiple genes linked to immune functions including inflammation, immune cell development and cell-cell signaling. Conclusions. These results reveal a novel pattern of immune dysregulation involving both aberrant inflammation and monocyte dysfunction, which suggests complex mechanisms linking monocytes and HIV/ART comorbidities.

Project description:Background: Monocytes and macrophages are implicated in inflammation and atherosclerosis, whereas monocytes are involved in psoriasis lesion formation. We previously reported a psoriatic inflammation-associated significant decrease in the membrane protein caveolin-1 (CAV-1) in psoriasis patient monocytes. However, the phenotype of circulating monocytes and their macrophage differentiation in psoriasis patients remain unclear. Objective: We sought to clarify circulating monocyte and monocyte-derived macrophage (MDM) phenotypes in psoriasis patients with and without comorbidities. Method: Thirty-one patients with psoriasis vulgaris and 28 control subjects were included. Surface macrophage markers and inflammatory status were examined in circulating monocytes and MDMs from both groups. Expression of CD36, which mediates macrophage uptake of oxidized low-density lipoprotein (oxLDL), was evaluated in these cells. CAV-1-silenced monocytes were differentiated into macrophages to investigate the effects of CAV-1 downregulation on psoriatic inflammation and atherosclerosis. Results: Macrophage surface markers were detectable in circulating monocytes. A significant M1 shift was detected in monocytes and MDMs in psoriasis patients, including those without cardiovascular disease risk factors, as compared to controls. MDMs of psoriasis patients had more CD36-expressing cells, which are associated with atherosclerosis risk. Additionally, CAV-1-silencing in monocytes increased the likelihood of M1-biased macrophage differentiation and increased pro-inflammatory cytokine production. Conclusions: Monocytes from psoriasis patients were more likely to differentiate into M1-dominant macrophages, correlating with inflammatory status and CAV-1 expression. These aberrant inflammatory monocytes not only contribute to psoriatic inflammation by producing psoriatic cytokines, but also have a phenotype that could increase atherosclerosis risk by uptake of oxLDL and formation of foam cells.

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Lipoprotein(a) integrates monocyte-mediated thrombosis and inflammation in atherosclerotic cardiovascular disease

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