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Ondracek AS, Hofbauer TM, Wadowski PP, Mangold A, Gremmel T, Lang IM. P6396LDL cholesterol promotes neutrophil extracellular trap formation. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz746.0992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Pro-protein convertase subtilisin/kexin 9 (PCSK9) is a regulator of low density lipoprotein (LDL) receptor (LDLR) expression and has gained attention in the treatment of hyperlipidemia. Serum levels of LDL are correlated with numbers of activated neutrophils in the circulation of hyperlipidemic patients. Activated neutrophils can form neutrophil extracellular traps (NETs) by expelling their chromatin, and NETs have been recognized as important risk factors for acute myocardial infarction (AMI) and stroke.
Purpose
We analyzed the influence of serum LDL levels on neutrophil activation, their propensity to form NETs, and the correlation of NET surrogate markers with systemic inflammatory responses in AMI.
Methods
We recruited 249 consecutive patients with AMI (mean age 58 years, 20% females) and assessed laboratory parameters, inflammatory markers, and serum lipid profiles 72 h after primary percutaneous coronary intervention. Double-stranded DNA (dsDNA) and citrullinated histone H3 were determined from plasma as markers of in vivo NET formation. In a subset of patients (n=25), ex vivo NET formation in response to PCSK9 and ionomycin was analyzed, neutrophils were stained for CD11b, LDLR, and lectin-like oxidized LDLR (LOX-1) using flow cytometry at baseline and after activation with phorbol myristate acetate. PCSK9 levels were measured by ELISA.
Results
Patients with serum LDL levels above the median [median (IQR) LDL 111 mg/dl (87–141), mean ± SD LDL 115±41 mg/dl] had significantly higher concentrations of circulating dsDNA.
Levels of dsDNA [median 121 ng/ml, IQR 101–156] were linked with levels of the specific NET marker citH3 [median (IQR) 252 ng/ml (655–1600), rs=0.157]. Plasma concentrations of dsDNA and citH3 correlated significantly with CRP (dsDNA rs=0.328; citH3 rs=0.209), proBNP (dsDNA rs=0.286; citH3 rs=0.192), troponin T (dsDNA rs=0.282; citH3 rs=0.197), and IL-6 (dsDNA rs=0.242; citH3 rs=0.216).
In the subset of patients in whom neutrophils were characterized, pre-treatment of neutrophils with PCSK9 could significantly decrease ionomycin induced NET release in a dose-dependent manner. Levels of serum LDL were associated with spontaneous NET formation (r=0.504) ex vivo and activated CD11b on neutrophils (r=0.495).
LOX-1 expression correlated significantly with LDLR expression (rs=0.670) and PCSK9 levels (r=0.520). Patient neutrophil stimulation in whole blood led to a significant decrease of the LDLR positive neutrophil population. This effect was greater when PCSK9 levels were higher.
Conclusion
Our data indicate a role for LDL in boosting neutrophil activation depending on PCSK9.
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Affiliation(s)
| | | | | | - A Mangold
- Medical University of Vienna, Vienna, Austria
| | - T Gremmel
- Medical University of Vienna, Vienna, Austria
| | - I M Lang
- Medical University of Vienna, Vienna, Austria
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