Raju Raghavan, Dalakas Marinos C
Neuromuscular Diseases Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10 Room 4N252, 10 Center Drive, Bethesda, MD 20892, USA.
Brain. 2005 Aug;128(Pt 8):1887-96. doi: 10.1093/brain/awh518. Epub 2005 Apr 27.
To explore the biological significance of gene expression in the pathogenesis of inflammatory myopathies, we performed microarray experiments followed by real-time PCR and immunohistochemistry on muscle biopsies obtained before and after therapy from patients with dermatomyositis (DM) who improved and patients with inclusion body myositis (sIBM) who did not improve after controlled trials with three monthly intravenous immunoglobulin (IVIg) infusions. The pretreatment biopsies showed high expression of immunoglobulin, adhesion molecules, chemokines and cytokine genes in both sIBM and DM (sIBM > DM). In the repeated biopsies of DM patients who clinically improved, 2206 genes were downregulated more than 1.5-fold; in contrast, 1700 of the same genes remained unchanged in sIBM patients who did not improve. Genes markedly downregulated in DM, but not sIBM, were interleukin 22, Kallmann syndrome 1 (KAL-1), an adhesion molecule shown for the first time in muscle, ICAM-1, complement C1q, and several structural protein genes. Because mRNA for KAL-1 was selectively upregulated in vitro by transforming growth factor (TGF) beta1, a fibrogenic cytokine immunolocalized in the endomysial connective tissue of pretreatment DM muscles, the downregulation of both TGF-beta and KAL-1 after IVIg only in DM suggests that these molecules have a functional role in connective tissue proliferation and fibrosis. The improved muscles of DM, but not sIBM, showed upregulation of chemokines CXCL9 (Mig) and CXCL11, and several immunoglobulin-related genes, suggesting an effect on muscle remodelling and regeneration. The results suggest that IVIg modulates several immunoregulatory or structural muscle genes, but only a subset of them associated with inflammatory mediators, fibrosis and muscle remodelling are connected with the clinical response. Gene arrays, when combined with clinical assessments, may provide important information in the pathogenesis of inflammatory myopathies.
为了探究基因表达在炎性肌病发病机制中的生物学意义，我们进行了微阵列实验，随后对皮肌炎（DM）患者（经三个月每月一次静脉注射免疫球蛋白（IVIg）对照试验后病情改善）和包涵体肌炎（sIBM）患者（经上述试验后病情未改善）治疗前后获取的肌肉活检样本进行实时PCR和免疫组织化学分析。治疗前的活检样本显示，sIBM和DM中免疫球蛋白、黏附分子、趋化因子和细胞因子基因均高表达（sIBM > DM）。在临床症状改善的DM患者的重复活检样本中，2206个基因下调超过1.5倍；相比之下，在病情未改善的sIBM患者中，相同的1700个基因未发生变化。在DM中显著下调但在sIBM中未下调的基因有白细胞介素22、卡尔曼综合征1（KAL-1）（一种首次在肌肉中发现的黏附分子）、细胞间黏附分子1（ICAM-1）、补体C1q以及几个结构蛋白基因。由于转化生长因子（TGF）β1（一种在治疗前DM肌肉的肌内膜结缔组织中免疫定位的促纤维化细胞因子）在体外可选择性上调KAL-1的mRNA，仅在DM中IVIg治疗后TGF-β和KAL-均下调，这表明这些分子在结缔组织增殖和纤维化中具有功能性作用。DM病情改善的肌肉而非sIBM的肌肉显示趋化因子CXCL9（Mig）和CXCL11以及几个免疫球蛋白相关基因上调，提示其对肌肉重塑和再生有影响。结果表明，IVIg可调节多个免疫调节或肌肉结构基因，但其中只有一部分与炎症介质、纤维化和肌肉重塑相关的基因与临床反应有关。基因阵列与临床评估相结合，可能为炎性肌病的发病机制提供重要信息。
