Mishra Shikha, Joshi Shaurya, Ward Jennifer E, Buys Eva P, Mishra Deepak, Mishra Deepa, Morgado Isabel, Fisch Sudeshna, Lavatelli Francesca, Merlini Giampaolo, Dorbala Sharmila, MacRae Calum A, Liao Ronglih
Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts.
Division of Cardiology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts.
Am J Physiol Heart Circ Physiol. 2019 May 1;316(5):H1158-H1166. doi: 10.1152/ajpheart.00788.2018. Epub 2019 Mar 15.
Cardiac dysfunction is the most frequent cause of morbidity and mortality in amyloid light chain (AL) amyloidosis caused by a clonal immunoglobulin light chain (LC). Previously published transgenic animal models of AL amyloidosis have not recapitulated the key phenotype of cardiac dysfunction seen in AL amyloidosis, which has limited our understanding of the disease mechanisms in vivo, as well as the development of targeted AL therapeutics. We have developed a transgenic zebrafish model in which a λ LC derived from a patient with AL amyloidosis is conditionally expressed in the liver under the control of the Gal4 upstream activation sequence enhancer system. Circulating LC levels of 125 µg/ml in these transgenic zebrafish are comparable to median pathological serum LC levels. Functional analysis links abnormal contractile function with evidence of cellular and molecular proteotoxicity in the heart, including increased cell death and autophagy. However, despite pathological and functional phenotypes analogous to human AL, the lifespan of the transgenic fish is comparable to control fish without the expressed AL-LC transgene. Nuclear labeling experiments suggest increased cardiac proliferation in the transgenic fish, which can be counteracted by treatment with a small molecule proliferation inhibitor leading to increased zebrafish mortality because of cardiac apoptosis and functional deterioration. This transgenic zebrafish model provides a platform to study underlying AL disease mechanisms in vivo further. Heart failure is a major cause of mortality in amyloid light (AL) amyloidosis, yet it has been difficult to model in animals. We report the generation of a transgenic zebrafish model for AL amyloidosis with pathological concentration of circulating human light chain protein that results in cardiac dysfunction. The light chain toxicity triggers regeneration in the zebrafish heart resulting in functional compensation early in life, but with age develops into cardiac dysfunction.
心脏功能障碍是由克隆性免疫球蛋白轻链（LC）引起的轻链（AL）淀粉样变性中发病和死亡的最常见原因。先前发表的AL淀粉样变性转基因动物模型并未重现AL淀粉样变性中所见心脏功能障碍的关键表型，这限制了我们对体内疾病机制的理解以及靶向AL疗法的开发。我们开发了一种转基因斑马鱼模型，其中源自一名AL淀粉样变性患者的λ LC在Gal4上游激活序列增强子系统的控制下在肝脏中条件性表达。这些转基因斑马鱼中循环LC水平为125 µg/ml，与病理血清LC水平中位数相当。功能分析将异常收缩功能与心脏中细胞和分子蛋白毒性的证据联系起来，包括细胞死亡和自噬增加。然而，尽管转基因鱼具有与人类AL类似的病理和功能表型，但其寿命与未表达AL-LC转基因的对照鱼相当。核标记实验表明转基因鱼心脏增殖增加，用小分子增殖抑制剂治疗可抵消这种增加，导致斑马鱼因心脏凋亡和功能恶化而死亡率增加。这种转基因斑马鱼模型为进一步研究体内潜在的AL疾病机制提供了一个平台。心力衰竭是轻链（AL）淀粉样变性中死亡的主要原因，但在动物中很难建模。我们报告了一种用于AL淀粉样变性的转基因斑马鱼模型的产生，该模型具有循环人类轻链蛋白的病理浓度，导致心脏功能障碍。轻链毒性触发斑马鱼心脏的再生，导致生命早期功能补偿，但随着年龄增长发展为心脏功能障碍。
