title: Silencing cardiomyocyte TLR4 reduces injury following hypoxia.
abstract: Toll-like receptor 4 (TLR4), the receptor for lipopolysaccharide (LPS) of gram-negative pathogens expressed in the heart, is activated by several endogenous ligands associated with tissue injury in response to myocardial infarction (MI). The aim of this study was to investigate the involvement of TLR4 signaling in cardiomyocytes dysfunction following hypoxia (90min) using multiple methodologies such as knocking down TLR4 and small interfering RNA (siTLR4). Cardiomyocytes of C57Bl/6 mice (WT) subjected to hypoxic stress showed increased cardiac release of LDH, HMGB1, IκB, TNF-α and myocardial apoptotic and necrotic markers (BAX, PI) compared to TLR4 knock out mice (TLR4KO). Treating these cardiomyocytes with siRNA against TLR4 decreased the damage markers (LDH, IκB, TNF-α). TLR4 silencing during hypoxic stress resulted in the activation of the p-AKT and p-GSK3β (by ∼25%). The latter is an indicator that there is a reduction of mitochondrial permeability transition pore (mPTP) opening following hypoxic myocardial induced injury leading to preserved mitochondrial membrane potential. Silencing TLR4 in cardiomyocytes improved cell survival following hypoxic injury through activation of the AKT/GSK3β pathway, reduced inflammatory and apoptotic signals. These findings suggest that TLR4 may serve as a potential target in the treatment of ischemic myocardial injury. Moreover, RNA interfering targeting TLR4 expression represents a therapeutic strategy.
authors.affiliation: The Mina & Everard Goodman Faculty of Life Sciences Bar-Ilan University, Ramat Gan, Israel; The Cardiac Research Laboratory of the Department of Cardiothoracic Surgery, Felsenstein Medical Research Center, Rabin Medical Center, Tel Aviv University, Petah Tikva, Israel.
authors.forename: Orna
authors.initials: O
authors.lastname: Avlas
authors.affiliation: The Mina & Everard Goodman Faculty of Life Sciences Bar-Ilan University, Ramat Gan, Israel.
authors.forename: Smadar
authors.initials: S
authors.lastname: Srara
authors.affiliation: The Mina & Everard Goodman Faculty of Life Sciences Bar-Ilan University, Ramat Gan, Israel.
authors.forename: Asher
authors.initials: A
authors.lastname: Shainberg
authors.affiliation: The Cardiac Research Laboratory of the Department of Cardiothoracic Surgery, Felsenstein Medical Research Center, Rabin Medical Center, Tel Aviv University, Petah Tikva, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Aravot
authors.affiliation: The Cardiac Research Laboratory of the Department of Cardiothoracic Surgery, Felsenstein Medical Research Center, Rabin Medical Center, Tel Aviv University, Petah Tikva, Israel. Electronic address: hochhaus@post.tau.ac.il.
authors.forename: Edith
authors.initials: E
authors.lastname: Hochhauser
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D015687:Cell Hypoxia; D020868:Gene Silencing; D000071679:Glycogen Synthase Kinase 3 beta / Q000378:metabolism; D024243:HMGB1 Protein / Q000378:metabolism; D007249:Inflammation / Q000473:pathology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D024243:HMGB1 Protein; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D011494:Protein Kinases; D000071679:Glycogen Synthase Kinase 3 beta
keywords: Cardiomyocyte; HMGB1; TLR4; TNF-α; p-GSK3β; siRNA