Objective To explore the effects of mechanical stimulation on the expression of autoantigens in myoblasts. Methods According to different processing methods, C2C12 cells were divided into the experimental group and control group; the experimental group was divided into 4 subgroups: 2-, 4-, and 6-day and 1-day stretch groups. In 2-, 4-, and 6-day stretch groups, mechanical loading was added on the C2C12 cells at a stretching frequency of 0.25 Hz and cellular deformation amplitude of 10%, 2 hours a day for 2, 4, and 6 days respectively by Flexercell 5000 strain unit, and at a stretching frequency of 1 Hz and cellular deformation amplitude of 15% for 1 hour in 1-day stretch group. In the control group, the cells were routinely cultured for 1, 2, 4, and 6 days (1-, 2-, 4-, and 6-day control). The cells were observed by inverted phase contrast microscope. The cell proliferation was detected by flow cytometry; the expressions of autoantigens were detected by Western blot method, including the Ku/the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), U1-70 (A part of ATP-dependent DNA helicase II), histidyl tRNA synthetase (HRS), and Mi-2 (reconfigurable components deacetylase complexes of NuRD). Results The exfoliated cells were found in 1-day stretch group, but no exfoliated cell was seen in the control group for 1-day culture. The cells proliferated more obviously in 2-day stretch group than in the control group for 2-day culture; cell differentiation was found in 4-day stretch group, and cell fusion in 6-day stretch group, which were similar to those in the control group for 4- and 6-day culture. After single stretching, cell apoptosis was found in 1-day stretch group, showing no significant difference in the relative DNA proliferation index (DPI) when compared with DPI of control group for 1-day culture (t=0.346, P=0.747). After cyclic stretching, DPIs of 2- and 4- day stretch groups were significantly increased when compared with those of the control group for 2- and 4-day culture (P lt; 0.05), but no significant difference was found between control group for 6-day culture and 6-day stretch group (t=1.191, P=0.303). Compared with the control group for 2-day culture, the relative protein expression of autoantigens (DNA-Pkcs, Mi-2, HRS, and U1-70) in 2-day stretch group decreased significantly (P lt; 0.05), but no significant difference was found between control group for 4-day culture and 4-day stretch group (P gt; 0.05). The relative protein expressions of autoantigens in 4-day stretch group significantly increased when compared with those of 2-day stretch group (P lt; 0.05), but the relative protein expressions of autoantigens in the control group for 4-day culture significantly decreased when compared with those of the control group for 2-day culture (P lt; 0.05). Conclusion Short-term mechanical stimulation can inhibit the expressions of autoantigens in myoblasts, but with the time prolonging, cell differentiation and fusion and adaptation to mechanical stimulation would result in diminished inhibitory effect.
Idiopathic inflammatory myopathies are a group of connective tissue diseases characterized by nonsuppurative inflammation of the striated muscle. At present, the diagnostic criteria for polymyositis/dermatomyositis classification proposed by Bohan and Peter in 1976 is mainly used clinically. In clinical observations, it is found that myopathy involves not only skin and muscle but also affects many systems of the body. Interstitial lung disease occupies an important part, and it is an important cause of death of patients with inflammatory myopathy. Patients with idiopathic myositis should be examined as early as possible by high-resolution CT to improve the detection rate of myositis-associated interstitial lung disease and start treatment as soon as possible. At the same time, the patients with myositis have different clinical manifestations due to specific antibodies in the serum; some specific antibodies may indicate poor prognosis and poor treatment response. Timely screening of patients with positive myositis-specific antibodies in patients with the pulmonary interstitial disease can help the patient’s diagnosis and treatment process.
Interstitial lung disease is the most common pulmonary complication in patients with inflammatory myopathy, with a high case fatality rate, unknown pathogenesis, and complex clinical manifestations, and the treatment is difficult. Early and timely treatment can improve the patient’s clinical symptoms and inhibit the development of the disease. The present treatment protocols can be mainly summarized as the commonly used drugs (corticosteroids, azathioprine, cyclophosphamide, mycophenolate mofetil, and intravenous immunoglobulin) and new drugs (cyclosporin A, tacrolimus, biological agents, and anti-fibrosis drug), etc. In this paper, the treatment progress of inflammatory myopathy-related interstitial lung disease and different myositis antibody-related interstitial lung disease in recent years at home and abroad is reviewed, so as to provide a basis for clinical treatment.
Existing classification methods for myositis ultrasound images have problems of poor classification performance or high computational cost. Motivated by this difficulty, a lightweight neural network based on a soft threshold attention mechanism is proposed to cater for a better IIMs classification. The proposed network was constructed by alternately using depthwise separable convolution (DSC) and conventional convolution (CConv). Moreover, a soft threshold attention mechanism was leveraged to enhance the extraction capabilities of key features. Compared with the current dual-branch feature fusion myositis classification network with the highest classification accuracy, the classification accuracy of the network proposed in this paper increased by 5.9%, reaching 96.1%, and its computational complexity was only 0.25% of the existing method. The obtained results support that the proposed method can provide physicians with more accurate classification results at a lower computational cost, thereby greatly assisting them in their clinical diagnosis.