Cardiovascular Research Advance Access [Accepted Manuscript] published online on January 30, 2009
Cardiovascular Research, doi:10.1093/cvr/cvp040
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IL-10 attenuates TNF-
-induced NF
B pathway activation and cardiomyocyte apoptosis
Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Center and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
Address for correspondence: Dr. Pawan K. Singal Professor and Director Institute of Cardiovascular Sciences St. Boniface General Hospital Research Center 351 Tache Ave, Room R3022 Winnipeg, Manitoba, R2H 2A6, Canada Tel: 204-235-3887 Fax: 204-233-6723 Email: psingal{at}sbrc.ca
Aim: We have recently reported that tumor necrosis factor-
(TNF-) increases oxidative stress and apoptosis in cardiomyocytes by upregulating p38 mitogen-activated protein (MAP) kinase phosphorylation. Interleukin-10 (IL-10) blocked these effects of TNF- by upregulating extracellular signal-regulated kinase 1/2 (ERK1/2) MAP kinase phosphorylation. However, the precise site of this IL-10 action is still unknown, and this was investigated in the present study.
Methods and Results: Cardiomyocytes isolated from adult Sprague Dawley rats were exposed to TNF- (10 ng/ml), IL-10 (10 ng/ml) and IL-10 + TNF- (ratio 1) for 4 hrs. Hydrogen peroxide and antioxidant trolox were used as positive controls. Exposure to TNF- resulted in an increase in the production of reactive oxygen species, the number of apoptotic cells, caspase-3 activation and poly-ADP ribose polymerase (PARP) cleavage. Increased oxidative stress by using hydrogen peroxide also caused apoptosis. The changes due to TNF- were associated with an increase in inhibitor of 
B kinase (IKK) and nuclear factor B (NFB) phosphorylation. IL-10 by itself had no effect, but it prevented the abovementioned TNF--induced changes. Trolox also mitigated TNF- induced changes. Pre-exposure of cells to an IKK inhibitor (PS-1145) prevented TNF--induced caspase-3 and PARP cleavage. Inhibition of ERK 1/2 MAP kinase with PD98059 attenuated the protective role of IL-10 against TNF--induced activation of IKK and NFB as well as cardiomyocyte apoptosis.
Conclusions: The present study shows that TNF--induced activation of the NFB pathway plays a critical role in cardiomyocyte apoptosis. IL-10 prevents TNF-induced NFB activation and proapoptotic changes in cardiomyocytes by inhibiting IKK phosphorylation through the activation of ERK 1/2 MAP kinase.
Time for primary review: 24 Days
* Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic