We have recently reported that tumour necrosis factor-α (TNF-α) increases oxidative stress and apoptosis in cardiomyocytes by upregulating p38 mitogen-activated protein (MAP) kinase (MAPK) phosphorylation. Interleukin-10 (IL-10) blocked these effects of TNF-α by upregulating extracellular signal-regulated kinase 1/2 (ERK 1/2) MAPK phosphorylation. However, the precise site of this IL-10 action is still unknown, and this is investigated in the present study. Cardiomyocytes isolated from adult Sprague–Dawley rats were exposed to TNF-α (10 ng/mL), IL-10 (10 ng/mL), and IL-10+TNF-α (ratio 1) for 4 h. Hydrogen peroxide and antioxidant trolox were used as positive controls. Exposure to TNF-α 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-α were associated with an increase in the inhibitor of κB kinase (IKK) and nuclear factor kappa-B (NFκB) phosphorylation. IL-10 by itself had no effect, but it prevented the above mentioned TNF-α-induced changes. Trolox also mitigated TNF-α induced changes. Pre-exposure of cells to an IKK inhibitor (PS-1145) prevented TNF-α-induced caspase-3 and PARP cleavage. Inhibition of ERK 1/2 MAPK with PD98059 attenuated the protective role of IL-10 against TNF-α-induced activation of IKK and NFκB as well as cardiomyocyte apoptosis. The present study shows that TNF-α-induced activation of the NFκB pathway plays a critical role in cardiomyocyte apoptosis. IL-10 prevents TNF-α-induced NFκB activation and pro-apoptotic changes in cardiomyocytes by inhibiting IKK phosphorylation through the activation of ERK 1/2 MAPK.

It is known that TNF-α increases the production of ROS and decreases antioxidant enzymes, resulting in an increase in oxidative stress. IL-10 appears to modulate these effects. The present study investigated the role of p38 and ERK1/2 MAPKs in mediating the interplay of TNF-α and IL-10 in regulating oxidative stress and cardiac myocyte apoptosis in Sprague-Dawley male rats. Isolated adult cardiac myocytes were exposed to TNF-α (10 ng/ml), IL-10 (10 ng/ml), and IL-10 + TNF-α ( ratio 1) for 4 h. H₂O₂(100 μM) as a positive control and the antioxidant Trolox (20 μmol/l) were used to confirm the involvement of oxidative stress. H₂O₂treatment increased oxidative stress and apoptosis; TNF-α mimicked these effects. Exposure to TNF-α significantly increased ROS production, caused cell injury, and increased the number of apoptotic cells and Bax-to-Bcl-xl ratio. This change was associated with an increase in the phospho-p38 MAPK-to-total p38 MAPK ratio and a decrease in the phospho-ERK1/2-to-total ERK1/2 ratio. IL-10 treatment by itself had no effect on these parameters, but it prevented the above-listed changes caused by TNF-α. The antioxidant Trolox modulated TNF-α-induced changes in Bax/Bcl-xl, cell injury, and MAPKs. Preexposure of cells to the p38 MAPK inhibitor SB-203580 prevented TNF-α-induced changes. Inhibition of the ERK pathway with PD-98059 attenuated the protective role of IL-10 against TNF-α-induced apoptosis. This study provides evidence in support of the essential role of p38 and ERK1/2 MAPKs in the interactive role of TNF-α and IL-10 in cardiac myocyte apoptosis.

Increase in oxidative/nitrosative stress is one of the mechanisms associated with the development of cardiotoxicity due to doxorubicin (Dox), a potent chemotherapy drug. Previously, we reported mitigation of Dox-induced oxidative/nitrosative stress and apoptosis by vitamin C (Vit C) in isolated cardiomyocytes. In the present in vivo study in rats, we investigated the effect of prophylactic treatment with Vit C on Dox-induced apoptosis, inflammation, oxidative/nitrosative stress, cardiac dysfunction, and Vit C transporter proteins. Dox (cumulative dose: 15 mg/kg) in rats reduced systolic and diastolic cardiac function and caused structural damage. These changes were associated with a myocardial increase in reactive oxygen species, reduction in antioxidant enzyme activities, increased expression of apoptotic proteins, and inflammation. Dox also caused an increase in the expression of proapoptotic proteins Bax, Bnip-3, Bak, and caspase-3. An increase in oxidative/nitrosative stress attributable to Dox was indicated by an increase in superoxide, protein carbonyl formation, lipid peroxidation, nitric oxide (NO), NO synthase (NOS) activity, protein nitrosylation, and inducible NOS protein expression. Dox increased the levels of cardiac proinflammatory cytokines TNF-α, IL-1β, and IL-6, whereas the expression of Vit C transporter proteins (sodium-ascorbate cotransporter 2 and glucose transporter 4) was reduced. Prophylactic and concurrent treatment with Vit C prevented all these changes and improved survival in the Vit C + Dox group. Vit C also improved Dox-mediated systolic and diastolic dysfunctions and structural damage. These results suggest a cardioprotective role of Vit C in Dox-induced cardiomyopathy by reducing oxidative/nitrosative stress, inflammation, and apoptosis, as well as improving Vit C transporter proteins.NEW & NOTEWORTHY This in vivo study provides novel data that vitamin C improves cardiac structure and function in doxorubicin-induced cardiomyopathy by reducing oxidative/nitrosative stress, apoptosis, and inflammation along with upregulation of cardiac vitamin C transporter proteins. The latter may have a crucial role in improving antioxidant status in this cardiomyopathy.

Uncontrolled production of oxygen and nitrogen radicals results in oxidative and nitrosative stresses that impair cellular functions and have been regarded as causative common denominators of many pathological processes. In this review, we report on the beneficial effects of molecular hydrogen in scavenging radicals in an artificial system of ^•OH formation. As a proof of principle, we also demonstrate that in rat hearts in vivo, administration of molecular hydrogen led to a significant increase in superoxide dismutase as well as pAKT, a cell survival signaling molecule. Irradiation of the rats caused a significant increase in lipid peroxidation, which was mitigated by pre-treatment of the animals with molecular hydrogen. The nuclear factor erythroid 2-related factor 2 is regarded as an important regulator of oxyradical homeostasis, as well as it supports the functional integrity of cells, particularly under conditions of oxidative stress. We suggest that the beneficial effects of molecular hydrogen may be through the activation of nuclear factor erythroid 2-related factor 2 pathway that promotes innate antioxidants and reduction of apoptosis, as well as inflammation.