Abstract
The synergy between radiotherapy and immunotherapy in treating thoracic cancers presents a potent therapeutic advantage, yet it also carries potential risks. The extent and nature of cumulative cardiac toxicity remain uncertain, prompting the need to discern its mechanisms and devise effective mitigation strategies. Radiation alone or in combination with an anti- Programmed cell death protein1 (PD-1) antibody significantly reduced cardiac function in C57BL/6J mice, and this pathologic effect was aggravated by anti-PD-1 (anti-PD-1 + radiation). To examine the cellular mechanism that causes the detrimental effect of anti-PD-1 upon cardiac function after radiation, AC16 human cardiomyocytes were used to study cardiac apoptosis and cardiac autophagy. Radiation-induced cardiomyocyte apoptosis was significantly promoted by anti-PD-1 treatment, while anti-PD-1 combined radiation administration blocked the cardiac autophagic flux. Adenosine 5'-triphosphate (ATP) (a molecule that promotes lysosomal acidification) not only improved autophagic flux in AC16 human cardiomyocytes, but also attenuated apoptosis induced by radiation and anti-PD-1 treatment. Finally, ATP administration in vivo significantly reduced radiation-induced and anti-PD-1-exacerbated cardiac dysfunction. We demonstrated for the first time that anti-PD-1 can aggravate radiation-induced cardiac dysfunction via promoting cardiomyocyte apoptosis without affecting radiation-arrested autophagic flux. ATP enhanced cardiomyocyte autophagic flux and inhibited apoptosis, improving cardiac function in anti-PD-1/radiation combination-treated animals.