Department of Cardiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
J Clin Immunol. 2010 Jul;30(4):520-30. doi: 10.1007/s10875-010-9388-3. Epub 2010 Apr 7.
While the molecular basis of dilated cardiomyopathy (DCM) remains uncertain, concrete evidence is emerging that sarcomeric and cytoskeleton gene expression of myocardium isolated from failing versus non-failing patients differ dramatically. The central aim to this work was to find out the possible role of dystrophin and titin along with the TNF-alpha in the pathogenesis of cardiomyopathy.
mRNA levels and protein expression of a cytoskeletal protein, dystrophin and a sarcomeric protein, titin in endomyocardial biopsies of DCM patients were examined using RT-PCR and immunohistochemistry, respectively. Further, we examined the effect of TNF-alpha on myocardial expression of titin and dystrophin in vitro in rat cardiac myoblast cell line (H9c2).
We observed significantly decreased mRNA and protein levels of dystrophin and titin in endomyocardial biopsy of DCM patients as compared to control group. The decreased levels of these proteins correlated with the severity of the disease. Plasma levels of both TNF-alpha and its soluble receptors TNFR1 and TNFR2 were found to be significantly higher in patients as compared to control group. Treatment of H9c2 cells with TNF-alpha resulted in a dose- and time-dependent decrease in mRNA levels of dystrophin and titin. Pretreatment of these cells with MG132, an inhibitor of nuclear factor kappa B (NF-kappaB) pathway, abolished TNF-alpha-induced reduction in mRNA levels of dystrophin and titin.
Our results suggest that reduced expression of dystrophin and titin is associated with the pathophysiology of DCM, and TNF-alpha may modulate the expression of these proteins via NF-kappaB pathway.
虽然扩张型心肌病（DCM）的分子基础仍不确定，但越来越多的具体证据表明，与非衰竭患者相比，来自衰竭患者的心肌中肌节和细胞骨架基因的表达有显著差异。这项工作的主要目的是确定肌营养不良蛋白和肌联蛋白以及 TNF-α在心肌病发病机制中的可能作用。
使用 RT-PCR 和免疫组织化学分别检查 DCM 患者心肌活检中细胞骨架蛋白肌营养不良蛋白和肌节蛋白肌联蛋白的 mRNA 水平和蛋白表达。此外，我们还在大鼠心肌成肌细胞系（H9c2）中研究了 TNF-α对心肌肌联蛋白和肌营养不良蛋白表达的体外影响。
与对照组相比，我们观察到 DCM 患者心肌活检中肌营养不良蛋白和肌联蛋白的 mRNA 和蛋白水平显著降低。这些蛋白水平的降低与疾病的严重程度相关。与对照组相比，患者的 TNF-α及其可溶性受体 TNFR1 和 TNFR2 的血浆水平均显著升高。用 TNF-α处理 H9c2 细胞会导致肌营养不良蛋白和肌联蛋白的 mRNA 水平呈剂量和时间依赖性降低。用核因子 kappa B（NF-kappaB）途径抑制剂 MG132 预处理这些细胞可消除 TNF-α诱导的肌营养不良蛋白和肌联蛋白 mRNA 水平的降低。
我们的结果表明，肌营养不良蛋白和肌联蛋白的表达降低与 DCM 的病理生理学有关，TNF-α可能通过 NF-kappaB 途径调节这些蛋白的表达。
