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Hemoglobin Induced Lipid Peroxidation as an Initiating Factor of Pulmonary Hypertension
Author(s) -
Irwin David,
Loomis Zoe L,
Redinius Katherine,
Eigenberger Paul,
Lisk Christina,
Buehler Paul
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.980.12
Subject(s) - lipid peroxidation , tlr9 , oxidative stress , chemistry , reactive oxygen species , oxidative phosphorylation , inflammation , biochemistry , microbiology and biotechnology , medicine , biology , gene expression , dna methylation , gene
Pulmonary hypertension (PH) is a common etiology of both inherited and acquired forms of hemolytic diseases. It is suspected that cell free hemoglobin (CFH) may initiate vascular remodeling and increased pulmonary pressures, however, the mechanisms behind this pathology remain unclear. It is understood that CFH increases reactive oxygen species and lipid peroxidation through reactions which are exacerbated in pro‐oxidative microenvironments. Recently, oxidative stress has been implicated in NFkB activation through a Toll like receptor 9 (TLR9) mediated pathway; it has been proposed that TLR9 is activated by either nuclear or mitochondrial DNA that has been liberated by stress induced cellular trauma. In this regard, the purpose of this investigation was to test whether hemoglobin induced oxidative stress triggers TLR9 mediated inflammation. We hypothesized that Hb induced lipid peroxidation is linked to TLR9 activation, resulting in IL6 induction and a corresponding activation of the smooth muscle cell proliferation indicative of pulmonary hypertension. Methods Rat pulmonary artery endothelial cells and smooth muscle cells (RPAEC and RPASMC) or HEK TLR9 reporter cells were incubated for 6–24h with HbFe 2+ and HbFe 3+ in the presence or absence of glucose oxidase (GOX). Lipid peroxidation, TLR9 activity, IL6 expression, and SMC activation were determined using CLICK chemistry, NFkB inducible enzymatic assay, qRTPCR and MTT assay, respectively. Results HbFe 2+ and HbFe 3+ (with or without GOX) induced lipid peroxidation in RPAEC and reporter cell TLR9 activation; IL6 expression in RPAEC was increased when incubated with HbFe2+ and HbFe3+; RPASMC demonstrated a more proliferative state when co‐cultured with RPAEC treated with HbFe2+ and HbFe3+. Glucose oxidase augmented the Hb induced phenotypes in all experiments. Conclusions Hb‐induced lipid peroxidation is associated with TLR9 activation, IL6 induction, and SMC activation. As such, CFH may be an initiating factor and mediator of pulmonary hypertension associated with hemolytic diseases, thus providing clinicians with a potential therapeutic target. Support or Funding Information NIH NLBI 1RO1HL125642‐01A1