Ulusoy Canan, Çavuş Filiz, Yılmaz Vuslat, Tüzün Erdem
a Department of Neuroscience , Aziz Sancar Institute for Experimental Medical Research, Istanbul Faculty of Medicine, Istanbul University , Istanbul , Turkey.
b Department of Genetics, Aziz Sancar Institute for Experimental Medical Research, Istanbul Faculty of Medicine , Istanbul University , Istanbul , Turkey.
Immunol Invest. 2017 Jul;46(5):490-499. doi: 10.1080/08820139.2017.1299754. Epub 2017 Apr 4.
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction (NMJ), characterized with muscle weakness. While MG develops due to acetylcholine receptor (AChR) antibodies in most patients, antibodies to muscle-specific receptor tyrosine kinase (MuSK) or low-density lipoprotein receptor-related protein 4 (LRP4) may also be identified. Experimental autoimmune myasthenia gravis (EAMG) has been previously induced by both LRP4 immunization and passive transfer of LRP4 antibodies.
Our aim was to confirm previous results and to test the pathogenic effects of LRP4 immunization in a commonly used mouse strain C57BL/6 (B6) using a recombinantly expressed human LRP4 protein.
B6 mice were immunized with human LRP4 in CFA, Torpedo Californica AChR in CFA or only CFA. Clinical and pathogenic aspects of EAMG were compared among groups.
LRP4- and AChR-immunized mice showed comparable EAMG clinical severity. LRP4-immunized mice displayed serum antibodies to LRP4 and NMJ IgG and complement factor C3 deposits. IgG2 was the dominant anti-LRP4 isotype. Cultured lymph node cells of LRP4- and AChR-immunized mice gave identical pro-inflammatory cytokine (IL-6, IFN-γ and IL-17) responses to LRP4 and AChR stimulation, respectively.
Our results confirm the EAMG-inducing action of LRP4 immunization and identify B6 as a LRP4-EAMG-susceptible mouse strain. Demonstration of complement fixing anti-LRP4 antibodies in sera and complement/IgG deposits at the NMJ of LRP4-immunized mice indicates complement activation as a putative pathogenic mechanism. We have thus developed a practical LRP4-induced EAMG model using a non-conformational protein and a widely available mouse strain for future investigation of LRP4-related MG.
重症肌无力（MG）是一种神经肌肉接头（NMJ）的自身免疫性疾病，其特征为肌肉无力。虽然大多数患者的MG是由乙酰胆碱受体（AChR）抗体引起的，但也可能检测到肌肉特异性受体酪氨酸激酶（MuSK）或低密度脂蛋白受体相关蛋白4（LRP4）的抗体。实验性自身免疫性重症肌无力（EAMG）此前已通过LRP4免疫和LRP4抗体的被动转移诱导产生。
我们的目的是证实先前的结果，并使用重组表达的人LRP4蛋白在常用的小鼠品系C57BL/6（B6）中测试LRP4免疫的致病作用。
用CFA中的人LRP4、CFA中的加州电鳐AChR或仅用CFA免疫B6小鼠。比较各组EAMG的临床和致病情况。
LRP4免疫组和AChR免疫组小鼠的EAMG临床严重程度相当。LRP4免疫组小鼠出现针对LRP4的血清抗体以及NMJ处IgG和补体因子C3沉积。IgG2是主要的抗LRP4同种型。LRP4免疫组和AChR免疫组小鼠培养的淋巴结细胞分别对LRP4和AChR刺激产生相同的促炎细胞因子（IL-6、IFN-γ和IL-17）反应。
我们的结果证实了LRP4免疫诱导EAMG的作用，并确定B6是一种对LRP4-EAMG易感的小鼠品系。在LRP4免疫组小鼠血清中证实存在补体结合抗LRP4抗体以及在NMJ处存在补体/IgG沉积，表明补体激活是一种可能的致病机制。因此，我们使用一种非构象蛋白和一种广泛可用的小鼠品系开发了一种实用的LRP4诱导的EAMG模型，用于未来对LRP4相关MG的研究。
