Clinical Analysis Of Anti-MDA5 Antibody-positive Dermatomyositis With Interstitial Lung Disease

BackgroundDermatomyositis(DM)is an idiopathic inflammatory myopathy characterized by skin lesions,and is a heterogeneous group of systemic autoimmune rheumatic diseases.It is usually characterized by muscle and extramuscular manifestations,especially skin and lung diseases of varying severity.According to the clinical manifestations of patients,the degree of skin and muscle involvement,DM is divided into the following two categories:classic DM(CDM)and clinical myopathic DM(CADM).Patients with CDM show obvious rash and skin inflammation,and proximal muscle weakness and myositis,while patients with CADM show typical rash and inflammation,but no obvious muscle weakness.Myositis-specific autoantibodies(MSA)are found in about 50-70%of patients and are important biomarkers.MSA is associated with characteristic clinical manifestations and may be helpful in the diagnosis,treatment and prognosis of DM and related complications.Anti-melanoma differentiation-associated gene 5 antibody(anti-MDA5 Ab),also known as anti-clinical myopathy dermatomyositis(CADM)-140 antibody,is the main MSA ingredient.The antibody was first discovered in Japanese patients by Sato et al.In 2005.MDA5-encoded RNA helicase is the main autoantigen of anti-MDA5 antibodies,can recognize double-stranded RNA viruses,participate in innate immunity,and is positive for anti-MDA5 antibodies in up to 48%of DM patients.Although a link has been identified between anti-MDA5 antibodies and the clinical features described,some controversy remains about this link.Because 46%of anti-MDA5 antibody-positive patients died of rapid progressive interstitial lung disease(RP-ILD)within 6 months of onset,it was initially speculated that anti-MDA5 antibodies were an important factor in disease progression.Objective1.By analyzing the clinical characteristics,laboratory indicators and imaging examination of DM-ILD patients with MDA5 antibody positive and MDA5 antibody negative,further explore the evaluation of the severity of DM-ILD by anti-MDA5 antibody.2.To explore the significance of anti-MDA5 antibody in the prognosis of DM-ILD disease.MethodsA total of 86 patients with DM-ILD who were admitted to the Department of Respiratory and Rheumatological Immunology of the First Affiliated Hospital of Zhengzhou University from March 2018 to September 2019 were collected,and the serum and clinical data of the patients were collected.According to the results of the patients' anti-MDA5 antibodies,they were divided into anti-MDA5 antibody positive group A(39 cases)and anti-MDA5 antibody negative group B(47 cases).Patients in group A were divided into death group(10 cases)and survival group(29 cases)according to their outcome during follow-up.General information between groups,serological markers(anti-MDA5 antibody titer,KL-6,anti-Ro52 antibody,SF),lung function(FVC,DLCO),chest high resolution CT(high resolution CT,HRCT)For analysis.Results1.There are 86 subjects in this study,females are more common,accounting for 71.1%.The average age is 50(43,55.25)years old.The proportion of patients with myopathy-free dermatomyositis(CADM)in group A was greater than that in group B,and the differences were statistically significant(P<0.05).2.The titers of anti-MDA5 antibodies in group A and group A were not statistically.significant(P>0.05).Anti-MDA5 antibody titer level was positively correlated with HRCT score and SF(P<0.05).3.The level of KL-6 in group A was higher than that in group B,and the differences were statistically significant(all P<0.05).KL-6 level was positively correlated with HRCT score and negatively correlated with DLCO and FVC(P<0.05).4.Among anti-MDA5 antibody-positive patients,the severity of ILD is related to anti-Ro52 antibody(P<0.05),the positive rate of anti-Ro52 antibody was 68.57%,of which the anti-Ro52 positive rate was 87.5%in RP-ILD patients,and the anti-Ro52 antibody positive rate in patients with chronic ILD and asymptomatic ILD decreased.5.Both FVC and DLCO decreased more in group A than group B,and the difference was statistically significant(both P<0.05).However,there was no significant difference in FVC and DLCO between the dead group and the surviving group(P>0.05).6.Suffering from RP-ILD,HRCT score and SF are significantly correlated with prognosis,but they are not independent risk factors(P>0.05).7.The cumulative survival rate of group A was lower than that of group B,the difference was statistically significant(P<0.05),and the 90-day survival rate was 78.6%.Conclusion1.DM-ILD occurs mostly in middle-aged women.For patients with CADM,routine investigation should be conducted to check whether ILD is combined,so as not to delay treatment and affect prognosis.2.Serum KL-6 level can be used to predict and evaluate the severity of anti-MDA5 antibody positive DM-ILD disease.3.Anti-MDA5 antibody titer level,SF,HRCT scores are all related to the prognosis of DM-ILD,SF is an independent risk factor,and SF level>1294ng/mL,poor prognosis.4.Anti-MDA5 antibody positive patients have extremely high risk of ILD,poor prognosis and high mortality.