(3R)-5,6,7-trihydroxy-3-isopropyl-3-methylisochroman-1-one reduces lipoteichoic acid-induced damage in rat cardiomyoblast cells

Abstract

Objective:Infective endocarditis is usually caused by Streptococcus sanguinis and characterized by inflammatory responses in the endocardium. This study aimed to investigate if the new compound (3R)-5,6,7-trihydroxy-3-isopropyl-3-methylisochroman-1-one (TIM) isolated from Alpinia katsumadai Hayata could provide protection against lipoteichoic acid (LTA)-induced cell damage in embryonic rat heart cells (H9c2).Methods:LTA-induced cell damage was established in H9c2, and the protective effects of TIM against the cell damage were examined at different concentrations (0.1–2.5 µM). The inflammatory response and oxidative stress in H9c2 cells were also measured.Results:Treatment with TIM (0.1–2.5 µM) significantly decreased LTA-induced toxicity in H9c2 cells, which was indicated by increase in cell viability, elevation in the mitochondrial membrane potential, decrease in the release of cytochrome-c and DNA damage, inhibition of caspase-3/9 activities, and change in apoptosis-related protein expression in LTA-treated H9c2 cells. TIM treatment also significantly attenuated the redox imbalance in H9c2 cells by decreasing malondialdehyde and intracellular reactive oxygen species levels as well as by enhancing superoxide dismutase activities and glutathione levels by increasing nuclear factor (erythroid-derived 2)-like 2 protein expression. Moreover, TIM treatment decreased interleukin 1 β, interleukin 12, and tumor necrosis factor α levels by inhibiting nuclear factor kappa B protein expression.Conclusion:Our data indicated that TIM protected H9c2 cells against LTA-induced toxicity, at least partially through inhibiting the inflammatory response and oxidative stress, providing scientific rational to develop TIM to treat infective endocarditis.

Lipoteichoic acid reduces antioxidant enzymes in H9c2 cells

“…The present study differs from the previous report [28] in cell viability, GSH content, and Nrf2 evaluation. This difference may be secondary to the DMSO use to dissolve LTA and to the differences in the employed methodologies.…”

“…LTA treatment depleted GPx-1, CAT and SOD levels at 0.1 to 5 and 0.1 to 15 μg/ml concentrations, respectively. LTA treatment decreased SOD-1 and might attenuate conversion of O 2 • ¯ into H 2 O 2 ; our data agree with those obtained by Liu et al, [28]. Besides, the decreased expression of GPx-1 and CAT enzymes may enhance H 2 O 2 levels that may lead to increased OH • production in the presence of free iron or O 2 • ¯.…”

“…LTA treatment induced a significant increase with carboxy-DCF and DHE at 10 μg/ml concentration, indicating that LTA ligand enhances ROS and RNS production in H9c2 cells. Results of this work agree with other studies in which it has been shown that LTA increases ROS production using carboxy-H 2 DCFDA in brain astrocytes (RBA-1), human dermal fibroblasts (HDF), human tracheal smooth muscle cells (HTSMC), rat lung microvessel endothelial cells (RLMVEC), spinal cord microglia [8,[37], [38], [39]] and recently in H9c2 cells [28] or using DHE in RLMVEC cells [8,[37], [38], [39]]. It has described that NADPH oxidase [8,37,39], mitochondrial dysfunction [28] and NOS [24] are responsible for ROS and RNS production, respectively.…”

“…In this study, LTA did not show a cytotoxic effect in H9c2 cells and confirms what was previously found by Gutierrez-Venegas et al [27]. However, Liu et al [28] found a reduction in cell viability, probably due to the usage of DMSO to dissolve LTA [29] and a different LTA source (which was not indicated).…”

“…Probably, ROS production, especially OH • , affected SOD-1, CAT, even GPx-1 enzymatic activity; for that reason, CAT increased their levels to high concentrations of LTA; however, ROS production continued to increase. These ideas are supported by Liu et al, which found SOD activity reduction induced by LTA [28]. Besides, the LTA concentration range employed in this research is biologically relevant; it can be achieved in the dead space of an intravascular catheter with biofilm (10 7 to 10 9 colony-forming units) [38] that can induce IE in an “ in vivo ” model [46].…”