Data_Sheet_1_Divergent Cardiac Effects of Angiotensin II and Isoproterenol Following Juvenile Exposure to Doxorubicin.XLSX

Hypertension is the most significant risk factor for heart failure in doxorubicin (DOX)-treated childhood cancer survivors. We previously developed a two-hit mouse model of juvenile DOX-induced latent cardiotoxicity that is exacerbated by adult-onset angiotensin II (ANGII)-induced hypertension. It is still not known how juvenile DOX-induced latent cardiotoxicity would predispose the heart to pathologic stimuli that do not cause hypertension. Our main objective is to determine the cardiac effects of ANGII (a hypertensive pathologic stimulus) and isoproterenol (ISO, a non-hypertensive pathologic stimulus) in adult mice pre-exposed to DOX as juveniles. Five-week-old male C57BL/6N mice were administered DOX (4 mg/kg/week) or saline for 3 weeks and then allowed to recover for 5 weeks. Thereafter, mice were administered either ANGII (1.4 mg/kg/day) or ISO (10 mg/kg/day) for 14 days. Juvenile exposure to DOX abrogated the hypertrophic response to both ANGII and ISO, while it failed to correct ANGII- and ISO-induced upregulation in the hypertrophic markers, ANP and BNP. ANGII, but not ISO, worsened cardiac function and exacerbated cardiac fibrosis in DOX-exposed mice as measured by echocardiography and histopathology, respectively. The adverse cardiac remodeling in the DOX/ANGII group was associated with a marked upregulation in several inflammatory and fibrotic markers and altered expression of Ace, a critical enzyme in the RAAS. In conclusion, juvenile exposure to DOX causes latent cardiotoxicity that predisposes the heart to a hypertensive pathologic stimulus (ANGII) more than a non-hypertensive stimulus (ISO), mirroring the clinical scenario of worse cardiovascular outcome in hypertensive childhood cancer survivors.

高血压是接受多柔比星（DOX）治疗的儿童癌症幸存者发生心力衰竭的最重要风险因素。我们先前开发了一种青少年DOX诱导的潜伏性心脏毒性两打击小鼠模型，该模型由成年期血管紧张素II（ANGII）诱导的高血压加剧。目前尚不清楚青少年DOX诱导的潜伏性心脏毒性如何使心脏对不会引起高血压的病理性刺激产生易感性。我们的主要目标是确定ANGII（一种高血压病理性刺激）和异丙肾上腺素（ISO，一种非高血压病理性刺激）在成年小鼠中作为青少年预先暴露于DOX时的心脏效应。五周龄的雄性C57BL/6N小鼠接受了3周的DOX（4 mg/kg/周）或盐水处理，然后允许其恢复5周。此后，小鼠被给予ANGII（1.4 mg/kg/天）或ISO（10 mg/kg/天）处理14天。青少年期对DOX的暴露消除了对ANGII和ISO的肥大反应，但未能纠正ANGII和ISO诱导的肥大标志物ANP和BNP的上调。ANGII但不是ISO，在DOX暴露小鼠中通过超声心动图和病理学分别测量的心脏功能恶化，加剧了心脏纤维化。DOX/ANGII组的恶性心脏重塑与多个炎症和纤维化标志物的显著上调以及RAAS中关键酶Ace的表达改变有关。总之，青少年期对DOX的暴露导致潜伏性心脏毒性，使心脏对高血压病理性刺激（ANGII）比对非高血压刺激（ISO）更具易感性，这与高血压儿童癌症幸存者临床心血管结局恶化的情况相呼应。