Doxorubicin suppression of lymphatic function and therapeutic reversal

 描述(申请人提供)：在美国有500多万女性在乳腺癌手术和/或放射治疗后患有手臂淋巴水肿，淋巴水肿的发生率和严重程度因阿霉素(DOX)化疗而恶化。DOX导致淋巴水肿的机制尚不清楚，但由于其细胞毒性作用，它被认为涉及多种急性和迟发性淋巴系统损伤的机制。或者，在这个方案中，我们将探索这样一种假设，即DOX强烈而直接地抑制淋巴管收缩功能，并且DOX引起的淋巴流抑制可以被电压门控L型钙通道(CAL)的药物开放剂逆转。使用大鼠肠系膜淋巴系统作为我们的模型，我们将首次展示临床相关浓度的DOX直接抑制淋巴管的自发收缩(“泵送”)，淋巴管将细胞外液体从周围组织推向中心静脉，以防止淋巴水肿。淋巴管的自发收缩依赖于钙离子通过钙通道的内流，而DOX对淋巴管收缩的抑制作用可被钙通道开放剂部分逆转。基于这些发现，我们建议：1)确定DOX对分离淋巴管收缩活动的直接影响，2)使用膜片钳技术确定DOX是否阻断淋巴管平滑肌细胞上的钙通道，3)使用体内流式细胞术和高分辨率活体光学成像来确定DOX化疗对体内淋巴流的急性影响。

 DESCRIPTION (provided by applicant): More than 5 million women in the United States suffer from arm lymphedema after surgery and/or radiation for breast cancer, and the incidence and severity of lymphedema is worsened by doxorubicin (DOX) chemotherapy. The mechanism by which DOX contributes to lymphedema is poorly understood, but it is thought to involve multiple mechanisms of acute and delayed injury to the lymphatic system due to its cytotoxic effects. Alternatively, in this proposal, we will explore the hypothesis that DOX acutely and directly suppresses lymphatic contractile function and DOX-induced suppression of lymphatic flow can be reversed by pharmacological openers of voltage-gated L-type Ca2+ (CaL) channels. Using the rat mesenteric lymphatic system as our model, we will show for the first time that DOX at clinically relevant concentrations directly suppresses the spontaneous contractions ("pumping") of lymph vessels, which propel extracellular fluid from peripheral tissues to the central veins to prevent lymphedema. The spontaneous contractions of lymph vessels rely on Ca2+ influx through CaL channels, and DOX-induced suppression of lymphatic contractions can be partly reversed by CaL channel openers. Based on these findings, we propose to i) define the direct effect of DOX on the contractile activity of isolated lymph vessels, ii) use patch-clamp techniques to determine if DOX blocks CaL channels in lymphatic smooth muscle cells, and iii) use in vivo flow cytometry with high-resolution intravital optical imaging to define the acute effet of DOX chemotherapy on in vivo lymphatic flow.