Cardoso I, Saraiva M J
Molecular Neurobiology, IBMC, Porto University, Porto, Portugal.
FASEB J. 2006 Feb;20(2):234-9. doi: 10.1096/fj.05-4509com.
Familial amyloidotic polyneuropathy is an autosomal dominant disorder mainly characterized by the extracellular deposition of transthyretin, with special involvement of the peripheral nerve. Several animal models have been generated, including transgenic mice carrying the most prevalent TTR mutation (TTR Val30Met). TTR-Val30Met mice without endogenous TTR (TTR-Val30Met X TTR-KO) were previously analyzed in our laboratory and approximately 60% of the animals over 1 year of age were found to have deposition as amyloid, i.e., with Congo red (CR) -positive material, constituting a good tool to investigate the effect of drugs on TTR deposition and fibrillogenesis. We recently showed that the drug doxycycline acts in vitro as a TTR fibril disrupter. In the present work we assessed the activity of this drug in vivo in the TTR-Met30Val X TTR-KO mice. Doxycycline was administrated in the drinking water to 23- to 28-month-old mice over a period of 3 months. Immunohistochemistry analyses revealed no differences in nonfibrillar TTR deposition between treated (n=11) and untreated mice (n=11). However, CR-positive material was observed only in the control group (untreated) whereas none of the animals treated with doxycycline was CR-positive. Immunohistochemistry for several markers associated with amyloid, such as matrix metalloproteinase-9 (MMP-9) and serum amyloid P component (SAP), was performed. MMP-9 was altered with significantly lower levels in treated animals compared with the control group. Mouse SAP was absent in treated animals, being observed only in untreated animals presenting TTR congophilic deposits. These results indicate that doxycycline is capable of disrupting TTR CR-positive amyloid deposits and decreases standard markers associated with fibrillar deposition, being a potential drug in the treatment of amyloidosis.
家族性淀粉样多神经病是一种常染色体显性疾病，主要特征为转甲状腺素蛋白在细胞外沉积，尤其累及周围神经。已经构建了多种动物模型，包括携带最常见的转甲状腺素蛋白（TTR）突变（TTR Val30Met）的转基因小鼠。我们实验室之前分析了无内源性TTR的TTR-Val30Met小鼠（TTR-Val30Met X TTR-KO），发现约60%的1岁以上动物有淀粉样沉积，即刚果红（CR）阳性物质，这构成了一个研究药物对TTR沉积和纤维形成影响的良好工具。我们最近发现强力霉素在体外可作为TTR纤维破坏剂。在本研究中，我们评估了该药物在TTR-Met30Val X TTR-KO小鼠体内的活性。将强力霉素添加到饮用水中，对23至28月龄的小鼠给药3个月。免疫组织化学分析显示，治疗组（n = 11）和未治疗组（n = 11）小鼠的非纤维状TTR沉积没有差异。然而，仅在对照组（未治疗）中观察到CR阳性物质，而接受强力霉素治疗的动物均无CR阳性。对与淀粉样蛋白相关的几种标志物进行了免疫组织化学检测，如基质金属蛋白酶-9（MMP-9）和血清淀粉样P成分（SAP）。与对照组相比，治疗组动物的MMP-9水平显著降低。在治疗组动物中未检测到小鼠SAP，仅在出现TTR嗜刚果红沉积物的未治疗动物中观察到。这些结果表明，强力霉素能够破坏TTR CR阳性淀粉样沉积物，并降低与纤维状沉积相关的标准标志物水平，是治疗淀粉样变性病的一种潜在药物。
