| [Objective] The idiopathic inflammatory myopathies (ⅡM) are systemic autoimmune diseases characterized by chronic inflammation of skeletal muscle. Polymyositis (PM) and dermatomyositis (DM) are two common subtypes of IIM. Although the cause of PM/DM is incompletely understood, an autoimmune mechanism which is mediated by lymphocyte is thought to be central to the underlying pathogenesis. In order to gain better insight into the pathogenesis of PM/DM, investigation of the lymphocyte and its functions may be important. The aims of this study are to determine the levels of peripheral blood lymphocyte subsets in a relatively larger patient population with PM/DM, and to subsequently investigate their clinical significance. Then we preliminaryly examined autophagy in the peripheral blood T lymphocytes in patients with IIM to determine its role in the pathogenesis of the disease.[Methods] In the first part of this study: peripheral blood lymphocyte subsets were determined by flow cytometry in89patients with PM or DM. The association between clinical features and peripheral blood lymphocyte subsets was analyzed.In the second part of this study:peripheral blood T lymphocytes (PBTLs) were isolated from10active DM patients and9health controls to observe cell autophagy under transmission electron microscopy (TEM) and determine the expression of autophagy related markers by western blot, as well as immunol cytochemistry. Human Jurkat T cells were incubated with TRAIL or TNFa, and the cell autophagy related protein was detected by western blot, the proliferation and apoptosis of cells were observed by CCK-8and AnnexinV-FITC/PI respectively.[Results] The first part of this study indicated that patients with active DM showed significant decreases in counts of CD3+cell, CD3+CD4+cell and CD3+CD8+cell (848.7±446.6,534.8±279.8and257.2±157.9cell/mm3, respectively), compared with those in inactive DM (1632.4±622.5,1041.8±558.2and562.5±376.2cell/mm3, respectively) and healthy control (1376.3±389.7,834.4±278.6and457.9±170.4cell/mm3, respectively)(F=12.901,8.257,7.084; P<0.05).6patients relievd after treatment were followed up to detect peripheral blood lymphocyte subsets. Their CD3+and CD3+CD4+cell counts were514.0±412.1and255.0±127.0cell/mm3before treatment, compared with833.5±470.5and449.2±146.0cell/mm3after treatment (t-5.714and-3.665, P<0.05). Logistic regression analysis indicated that myositis disease activity could influence the counts of peripheral blood CD3+cell, CD3+CD4+cell and CD3+CD8+cell (b=0.211,0.344,0.289; P<0.05). ILD in IIM could influence the counts of CD3+cell and the ratio of CD3+CD4+cell (b=0.928,1.974; P<0.05).7patients died in hospital or in the follow-up. Logistic regression analysis indicated that the counts of CD3+CD8+cell was risk factor for death, and relative risk was0.989(b=-0.011; P<0.05).The second part of this study indicated that autophagosome and autolysosome were present in PBTLs from a DM patient under TEM. No significant difference was found in protein expression of Beclinl between PBTLs from DM patients and healthy controls (P>0.05). There was no marked LC3expressed in PBTLs from DM patients, as well as healthy controls. But PBTLs from DM patients expressed higher LC3protein than healthy controls, after incubated with chloroquine. The expression of LC3protein in human Jurkat T cells did not change significantly with TNFa stimulated, but decreased with TRAIL stimulated. TRAIL and TNFa can equally cause the increase in the proportion of apoptosis in Jurkat T cells and inhibit cell proliferation activity.[Conclusion] Firstly, The identification and quantification of T cell subsets may serve as a reference marker for evaluating PM/DM disease activity. T cell subsets may also be useful in the comprehensive assessment of clinical lung involvement. Low counts of CD8+T lymphocyte significantly increase the risk of patient death, thereby predicting a poor outcome for patients with PM/DM. Secondly, Autophagy occurs in PBTLs from DM patients. Autophagy may be differently present in PBTLs between DM patients and healthy controls. TRAIL and TNFa play different roles in regulating autophagy in human Jurkat T cells. This may provide a new theoretical basis for the research of IIM. |
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