title: Oxidized LDL induced extracellular trap formation in human neutrophils via TLR-PKC-IRAK-MAPK and NADPH-oxidase activation.
abstract: Neutrophil extracellular traps (NETs) formation was initially linked with host defence and extracellular killing of pathogens. However, recent studies have highlighted their inflammatory potential. Oxidized low density lipoprotein (oxLDL) has been implicated as an independent risk factor in various acute or chronic inflammatory diseases including systemic inflammatory response syndrome (SIRS). In the present study we investigated effect of oxLDL on NETs formation and elucidated the underlying signalling mechanism. Treatment of oxLDL to adhered PMNs led to a time and concentration dependent ROS generation and NETs formation. OxLDL induced free radical formation and NETs release were significantly prevented in presence of NADPH oxidase (NOX) inhibitors suggesting role of NOX activation in oxLDL induced NETs release. Blocking of both toll like receptor (TLR)-2 and 6 significantly reduced oxLDL induced NETs formation indicating requirement of both the receptors. We further identified Protein kinase C (PKC), Interleukin-1 receptor associated kinase (IRAKs), mitogen-activated protein kinase (MAPK) pathway as downstream intracellular signalling mediators involved in oxLDL induced NETs formation. OxLDL components such as oxidized phospholipids (lysophosphatidylcholine (LPC) and oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (oxPAPC)) were most potent NETs inducers and might be crucial for oxLDL mediating NETs release. Other components like, oxysterols, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) were however less potent as compared to oxidized phospholipids. This study thus demonstrates for the first time that treatment of human PMNs with oxLDL or its various oxidized phopholipid component mediated NETs release, implying their role in the pathogenesis of inflammatory diseases such as SIRS.
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Deepika
authors.initials: D
authors.lastname: Awasthi
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Sheela
authors.initials: S
authors.lastname: Nagarkoti
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Megha
authors.initials: M
authors.lastname: Dubey
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Abhishek Kumar
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Priya
authors.initials: P
authors.lastname: Pathak
authors.affiliation: Department of Transfusion Medicine, King George's Medical University, Lucknow, India.
authors.forename: Tulika
authors.initials: T
authors.lastname: Chandra
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India.
authors.forename: Manoj Kumar
authors.initials: MK
authors.lastname: Barthwal
authors.affiliation: Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow, India. Electronic address: madhu_dikshit@cdri.res.in.
authors.forename: Madhu
authors.initials: M
authors.lastname: Dikshit
mesh_terms: D000447:Aldehydes / Q000494:pharmacology; D065206:Extracellular Traps / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D053592:Interleukin-1 Receptor-Associated Kinases / Q000235:genetics / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism* / Q000494:pharmacology; D008315:Malondialdehyde / Q000494:pharmacology; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism* / Q000473:pathology; D010084:Oxidation-Reduction / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D018746:Systemic Inflammatory Response Syndrome / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism
chemical_list: D000447:Aldehydes; D008077:Lipoproteins, LDL; D017382:Reactive Oxygen Species; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; C099252:oxidized low density lipoprotein; D008315:Malondialdehyde; D019255:NADPH Oxidases; D053592:Interleukin-1 Receptor-Associated Kinases; D011493:Protein Kinase C; C027576:4-hydroxy-2-nonenal
keywords: NADPH oxidase; Neutrophil extracellular traps; Oxidized low density lipoprotein; Oxidized phospholipids; Systemic inflammatory response syndrome