Holo-lipocalin-2–derived siderophores increase mitochondrial ROS and impair oxidative phosphorylation in rat cardiomyocytes

• Published in: Proceedings of the National Academy of Sciences - PNAS 2018-02, Vol.115 (7), p.1576-1581
• Main Authors: Song, Erfei, Ramos, Sofhia V., Huang, Xiaojing, Liu, Ying, Botta, Amy, Sung, Hye Kyoung, Turnbull, Patrick C., Wheeler, Michael B., Berger, Thorsten, Wilson, Derek J., Perry, Christopher G. R., Mak, Tak W., Sweeney, Gary
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants; Bioenergetics; Biological Sciences; Cardiomyocytes; Critical components; Dihydroxybenzoic acid; Endocytosis; Gentisates - pharmacology; Heart; Heart diseases; Hydroxybenzoates - pharmacology; Immune response; Immune system; Inflammation; Innate immunity; Iron; Iron - metabolism; Ischemia; Lipocalin; Lipocalin-2 - physiology; Male; Mice; Mice, Knockout; Mitochondria; Mitochondria - drug effects; Mitochondria - metabolism; Mitochondria - pathology; Myocytes, Cardiac - drug effects; Myocytes, Cardiac - metabolism; Myocytes, Cardiac - pathology; Oxidative Phosphorylation; Oxygen; Phosphorylation; Rats; Rats, Wistar; Reactive oxygen species; Reactive Oxygen Species - metabolism; Reperfusion; Reperfusion Injury - drug therapy; Reperfusion Injury - metabolism; Reperfusion Injury - pathology; Rodents; Siderophores; Siderophores - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1720570115

Lipocalin-2 (Lcn2), a critical component of the innate immune response which binds siderophores and limits bacterial iron acquisition, can elicit spillover adverse proinflammatory effects. Here we show that holo-Lcn2 (Lcn2–siderophore–iron, 1:3:1) increases mitochondrial reactive oxygen species (ROS) generation and attenuates mitochondrial oxidative phosphorylation in adult rat primary cardiomyocytes in a manner blocked by N-acetyl-cysteine or the mitochondria-specific antioxidant SkQ1. We further demonstrate using siderophores 2,3-DHBA (2,3-dihydroxybenzoic acid) and 2,5-DHBA that increased ROS and reduction in oxidative phosphorylation are direct effects of the siderophore component of holo-Lcn2 and not due to apo-Lcn2 alone. Extracellular apo-Lcn2 enhanced the potency of 2,3-DHBA and 2,5-DHBA to increase ROS production and decrease mitochondrial respiratory capacity, whereas intracellular apo-Lcn2 attenuated these effects. These actions of holo-Lcn2 required an intact plasma membrane and were decreased by inhibition of endocytosis. The hearts, but not serum, of Lcn2 knockout (LKO) mice contained lower levels of 2,5-DHBA compared with wild-type hearts. Furthermore, LKO mice were protected from ischemia/reperfusion-induced cardiac mitochondrial dysfunction. Our study identifies the siderophore moiety of holo-Lcn2 as a regulator of cardiomyocyte mitochondrial bioenergetics.