MYOCYTE RESPONSES DURING EXPERIMENTAL MYASTHENIA GRAVIS

乙酰胆碱受体(AChR)表达在肌膜上，负责接收神经发出的刺激肌肉收缩的信号。重症肌无力(MG)是一种神经肌肉疾病，是针对AChR的自身抗体导致肌肉收缩受损的结果。然而，循环血清中抗AChR抗体的滴度与MG患者的疾病严重程度并没有很好的相关性，这种相关性的缺乏导致了寻找其他因素来帮助确定最终的疾病严重程度。因此，我们的假设是肌肉不是MG疾病症状发展的被动参与者，事实上，肌肉通过产生免疫调节因子来发挥非常重要的积极作用，这些免疫调节因子可以影响免疫系统最终对肌肉的免疫病理影响。MG的实验大鼠模型将被用来检验这一假设。因此，用纯化的AChR免疫Lewis大鼠，可产生抗AChR抗体和实验性自身免疫性重症肌无力(EAMG)。研究的重点将是EAMG大鼠肌肉细胞产生细胞因子和对细胞因子的反应。在这方面，在存在或不存在来自Lewis大鼠的抗AChR抗体的情况下，肌肉细胞系将在体外暴露于选定的细胞因子。读数将是具有免疫调节活性的肌细胞产物的诱导(即细胞因子、趋化因子、膜相互作用分子)。同样，来自已知对EAMG(Wistar Furth)诱导具有抵抗力的大鼠品系的肌细胞系将被评估肌细胞反应的差异，这将解释疾病易感性的差异。结论根据体外观察，在免疫应答的诱导阶段，AChR免疫的Lewis大鼠以及接受了已知具有不同诱发疾病症状能力的预先形成的抗AChR抗体的大鼠将得到验证。

Acetylcholine receptors (AChR) are expressed on muscle membranes and are responsible for the reception of signals from nerves that stimulate muscle contraction. Myasthenia gravis (MG) is a neuromuscular disease that is the result of impaired muscle contraction caused by autoantibodies directed at the AChR. However, circulating serum titers of anti-AChR antibodies do not correlate well with disease severity in patients with MG and this lack of correlation has led to the search for other factors which may help determine eventual disease severity. Therefore, it is our hypothesis that muscle is not a passive participant in the development of disease symptoms in MG and, in fact, plays a very important active role by producing immunomodulating factors that can influence the eventual immunopathological impact of the immune system on muscle. The experimental rat model for MG is to be used to test this hypothesis. Accordingly, Lewis rats are to be immunized with purified AChR which results in the production of anti-AChR antibodies and Experimental Autoimmune Myasthenia Gravis (EAMG). Studies will focus on the production of, and responses to, cytokines by muscle cells in rats with EAMG. In this regard, muscle cell lines will be exposed in vitro to selected cytokines in the presence or absence of anti-AChR antibodies derived from Lewis rats. The readout will be the induction of myocyte products with immunomodulating activities (i.e., cytokines, chemokines, membrane interaction molecules). Similarly, myocyte cell lines derived from a rat strain known to be resistant to the induction of EAMG (Wistar Furth) will be evaluated for differences in myocyte responses that would explain differences in disease susceptibility. Conclusions based on in vitro observations will then be verified in AChR-immunized Lewis rats during the induction phase of the immune response, as well as in rats that have received pre-formed anti-AChR antibodies known to possess differing abilities to induce disease symptoms.