Secoisolariciresinol diglucoside abrogates oxidative stress-induced damage in cardiac iron overload condition.

Stephanie Puukila,Kailash Prasad,Carli Gurney,Adrian Agostino,Anna Laakso,Jessica Abdel-Malak,Sean Bryan,Adriane Belló-Klein,Neelam Khaper,Dinender K Singla

doi:10.1371/journal.pone.0122852

Abstract

Cardiac iron overload is directly associated with cardiac dysfunction and can ultimately lead to heart failure. This study examined the effect of secoisolariciresinol diglucoside (SDG), a component of flaxseed, on iron overload induced cardiac damage by evaluating oxidative stress, inflammation and apoptosis in H9c2 cardiomyocytes. Cells were incubated with 50 μ5M iron for 24 hours and/or a 24 hour pre-treatment of 500 μ M SDG. Cardiac iron overload resulted in increased oxidative stress and gene expression of the inflammatory mediators tumor necrosis factor-α, interleukin-10 and interferon γ, as well as matrix metalloproteinases-2 and -9. Increased apoptosis was evident by increased active caspase 3/7 activity and increased protein expression of Forkhead box O3a, caspase 3 and Bax. Cardiac iron overload also resulted in increased protein expression of p70S6 Kinase 1 and decreased expression of AMP-activated protein kinase. Pre-treatment with SDG abrogated the iron-induced increases in oxidative stress, inflammation and apoptosis, as well as the increased p70S6 Kinase 1 and decreased AMP-activated protein kinase expression. The decrease in superoxide dismutase activity by iron treatment was prevented by pre-treatment with SDG in the presence of iron. Based on these findings we conclude that SDG was cytoprotective in an in vitro model of iron overload induced redox-inflammatory damage, suggesting a novel potential role for SDG in cardiac iron overload.

Highlights

Iron is essential to biochemical, metabolic, and biological processes in all organisms, where it is the critical component of haemoglobin and is needed for energy production and detoxification [1]
A 24-hour treatment with 50 μM iron caused a significant increase (p < 0.05) in ROS generation (Fig 2A) as indicated by increased mean FL1 fluorescence versus control. These data indicate a pronounced production of ROS resulting from iron treatment of the H9c2 cells. 24-hour pre-treatment with 500 μM secoisolariciresinol diglucoside (SDG) prevented the significant increase in iron-induced ROS generation, reducing it to control levels (Fig 2A and 2B)
We found that pre-treatment with SDG prevented a significant increase in iron-induced apoptosis, suggesting that the observed iron-induced cytotoxicity is largely mediated by oxidative stress and inflammation

Summary

Introduction

Iron is essential to biochemical, metabolic, and biological processes in all organisms, where it is the critical component of haemoglobin and is needed for energy production and detoxification [1]. SDG in Cardiac Iron Overload impaired feedback inhibition of iron uptake, resulting in maximal absorption [5,6]. Chronic iron overload can lead to a variety of cardiac arrhythmias resulting in heart failure [2, 5,6,7,8]. No single mechanism is likely to account for the pathology of iron-overload induced heart failure, recent studies have suggested that altered calcium homeostasis and increased oxidative stress each play a role [5,6,7,8]. The mechanism of cardiac iron uptake is not well defined but recent studies have established that iron is transported by voltagedependent L-type Ca2+ channels in cardiomyocytes [2, 6, 8]

Methods

Results

Conclusion