Bioenergetics
Trypanosoma cruzi Induces the Reactive Oxygen Species-PARP-1-RelA Pathway for Up-regulation of Cytokine Expression in Cardiomyocytes*

https://doi.org/10.1074/jbc.M109.076984Get rights and content
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In this study, we demonstrate that human cardiomyocytes (AC16) produce reactive oxygen species (ROS) and inflammatory cytokines in response to Trypanosoma cruzi. ROS were primarily produced by mitochondria, some of which diffused to cytosol of infected cardiomyocytes. These ROS resulted in an increase in 8-hydroxyguanine lesions and DNA fragmentation that signaled PARP-1 activation evidenced by poly(ADP-ribose) (PAR) modification of PARP-1 and other proteins in infected cardiomyocytes. Phenyl-α-tert-butylnitrone blocked the mitochondrial ROS (mtROS) formation, DNA damage, and PARP-1 activation in infected cardiomyocytes. Further inhibition studies demonstrated that ROS and PARP-1 signaled TNF-α and IL-1β expression in infected cardiomyocytes. ROS directly signaled the nuclear translocation of RelA (p65), NF-κB activation, and cytokine gene expression. PARP-1 exhibited no direct interaction with p65 and did not signal its translocation to nuclei in infected cardiomyocytes. Instead, PARP-1 contributed to PAR modification of p65-interacting nuclear proteins and assembly of the NF-κB transcription complex. PJ34 (PARP-1 inhibitor) also prevented mitochondrial poly(ADP-ribosyl)ation (PARylation) and ROS formation. We conclude that T. cruzi-mediated mtROS provide primary stimulus for PARP-1-NF-κB activation and cytokine gene expression in infected cardiomyocytes. PAR modification of mitochondrial membranes then results in a feedback cycle of mtROS formation and DNA damage/PARP-1 activation. ROS, either through direct modulation of cytosolic NF-κB, or via PARP-1-dependent PAR modification of p65-interacting nuclear proteins, contributes to cytokine gene expression. Our results demonstrate a link between ROS and inflammatory responses in cardiomyocytes infected by T. cruzi and provide a clue to the pathomechanism of sustained inflammation in Chagas disease.

Oxygen/Radicals
Cytokines Induction
Mitochondria
NF-κB
Parasite
PARP-1
Trypanosoma cruzi
Cardiomyocytes

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This work was supported, in whole or in part, by National Institutes of Health Grants RO1-HL094802 from NHLBI and RO1-AI054578 from NIAID (to N. J. G.).