Am J Physiol Heart Circ Physiol. 2019 Jun 07.
Doxorubicin (Dox) induced cardiac side effects are regulated through increased oxidative stress and apoptosis. However, it remains unknown whether Dox induces the specific inflammatory-mediated form of cell death called pyroptosis. The current study is undertaken to determine whether Dox induces pyroptosis in an in vitro model, and to test the potential of exosomes-derived from embryonic stem cells (ES-Exos) in inhibiting pyroptosis. H9c2 cells were exposed to Dox to generate pyroptosis, and then subsequently treated with exosomes to investigate the protective effects of ES-Exos. Mouse embryonic fibroblast-exosomes (MEF-Exos) were used as a cell line control. We confirmed pyroptosis by analyzing presence of TLR4-NLRP3 inflammasome that initiates pyroptosis which was further confirmed with pyroptotic markers; caspase-1, IL-1β, caspase-11, and gasdermin-D. The presence of inflammation was confirmed for pro-inflammatory cytokines, TNF-α and IL-6. Our data shows that Dox exposure significantly (p<0.05) increases expression of TLR4, NLRP3, pyroptotic markers (caspase-1, IL-1β, caspase-11, and gasdermin-D), and pro-inflammatory cytokines (TNF-α and IL-6) in H9c2 cells. The increased expression of inflammasome, pyroptosis, and inflammation was significantly (p<0.05) inhibited by ES-Exos. Interestingly, our cell line control, MEF-Exos, did not show any protective effects. Furthermore, our cytokine array data suggests increased anti-inflammatory (IL-4, IL-9 and IL-13) and decreased pro-inflammatory cytokines (Fas ligand, IL-12 and TNF-α) in ES-Exos, suggesting that anti-inflammatory cytokines might be mediating the protective effects of ES-Exos. In conclusion, our data shows that Dox induces pyroptotic cell death in the H9c2 cell culture model, and is attenuated via treatment with ES-Exos.
Keywords: Doxorubicin; H9c2 cells; Inflammation; exosomes; pyroptosis