| Background and objectiveKL-6,found in the 1980 s is a kind of glycoprotein with a large molecular weight.Mainly secreted by alveolar type II epithelial cells,early as tumor markers of thymoma,recently there are a lot of researches on interstitial lung disease.It has a very strong chemotaxis on fibroblast,playing an important role in the process of pathological changes in fibrosis.Polymyositis and dermatomyositis(PM/DM)are systemic autoimmune diseases with striated muscle inflammation as the main performance.Interstitial lung disease(ILD)whose main accumulation in organs such as skin,gastrointestinal tract,heart,lung,etc,is the most frequent pulmonary complications,meanwhile,its high incidence,is one of the important factors affecting the prognosis of patients with PM/DM.Early diagnosis and treatment,for lesions changing from early grinding glass to irreversible honeycombing is crucial.At present there are no specific serum markers to judge the occurrence,treatment outcome and prognosis of ILD.Therefore,this study aims to explore diagnostic value and clinical relevance in polymyositis,dermatomyositis associated interstitial lung disease patients through the detection of KL-6 levels,and to explore the value of the course monitoring and prognosis evaluation in serum KL-6 for PM/DM with ILD.Research methods77 cases of PM/DM patients were selected from the First Affiliated Hospital of Zhengzhou University in May 2015 to May 2016,20 the other pulmonary infection patients and 30 cases of healthy person with the age,gender matched.PM/DM conformed to the diagnostic criteria took by Bohan/Peter about IIM in 1975.ILD based on lung function,chest imaging(X ray or HRCT)or lung biopsy.Pulmonary infection was confirmed by the etiology of inspection consistent with clinical manifestations,excluding tuberculosis,whereas,the chest HRCT or x-rays rule out patients with interstitial lung disease.Exclusion criteria:(1)the interstitial pneumonia with pulmonary infection,(2)other autoimmune diseases and lung diseases,(3)merging malignant tumor.According to whether merging ILD or not,PM/DM patients were divided into the PM/DM with ILD group,the PM/DM not merging ILD group.ELISA method was used to detect KL-6 levels in 77 cases of PM/DM patients,20 patients with lung infection and 30 cases of healthy,and PM/DM merging ILD patients with follow-up research.The association with KL-6 and diagnosis,clinical features,treatment,even and prognosis were analyzed.Using SPSS17.0 software analysis,measurement data for(sx ±)or(M,range),making comparison between the two groups,if it was the normal distribution,t test would be used;if the non-normal distribution,Wilcoxon test would be used.When comparisons between multiple sets of samples,LSD-t test would be used,with the counting data by chi-square test,then the receiver operating characteristic(ROC)was used to analyze the diagnostic values of the cut-off,the sensitivity and specificity,while the Spearman rank was used to analyze correlation,that P<0.05 was considered that the difference was statistically significant.Results1.The average of serum KL-6 in the PM/DM combined ILD group,the PM/DM not combined ILD group,the pulmonary infection group,the healthy group,were(1135.33±648.67),(321.58±182.14),(326.72±152.37),(230.14±114.39),respectively;Trough the LSD-t test,the level of serum KL-6 of the PM/DM combined ILD group was significantly higher than those of the PM/DM not combined ILD group,the pulmonary infection group and the healthy group(P<0.05);There were no statistically significance among the PM/DM not merge ILD group,the lung infection group and the healthy group(P>0.05),meanwhile the difference between the lung infection group and the healthy group was not statistically significant(P>0.05).Through the ROC curve analysis,the positive threshold of PM/DM with interstitial lung disease diagnosis was 507 U/ml,the AUC was(0.962±0.018),the 95%CI was(0.926~0.998),the sensitivity was 92.6%,the specificity was 82.0%,the positive predictive value was 73.5%,the negative predictive value was 95.3%.2.In 77 cases of PM/DM patients,the correlation analysis by the Spearman rank suggested that KL-6 levels and the DLco%pred(r=-0.765,P<0.01),the VC%pred(r=-0.584,P<0.01),the TLC%pred(r=-0.635,P<0.01)and the RV%pred(r=-0.615,P<0.01)were significantly negative correlation.With the FEV1%pred and the FEV1/FVC,there were no correlation(P>0.05).3.The normal up limit for the reference value of serum concentration of KL-6 was 500 U/ml,77 cases of PM/DM patients were divided into the KL-6 increased group and the KL-6 normal group.Through the chi-square test,it was found that the differences of positive rates of clinical features,such as dysphagia,muscle weakness,arthritis/pain,fever and Raynaud's phenomenon in the KL-6 increased group and the normal group were not statistically significant(P>0.05).To autoantibodies,such as anti-nuclear antibody,anti-Jo-1 antibody,the positive rate of anti-Jo-1 antibody in the KL-6 serum increased group was significantly higher than that in the normal group(2x=5.431,P=0.023),the difference of the ANA positive rate in the KL-6 increased group and the KL-6 normal group was not statistically significant(2x=0.856,P>0.05).By t test,differences of those laboratory indexes such as CRP,ESR,CK,AST and LDH in the KL-6 increased group and the KL-6 normal group were not statistically significant(P>0.05).4.Tracking 10 cases of PM/DM with ILD patients treatment,the comparison of before and after treatment,using the Wilcoxon test,showed that the serum KL-6 had statistically difference between before and after the treatment(P<0.05).5.Making follow-up of PM/DM patients with ILD for 1 ~ 13 months,found that five patients died,and KL-6 serum levels of the death group was obviously higher than that of the survival(t=7.596,P<0.05).The average values were(2663.60± 348.49),(995.14±459.18),respectively.Conclusions1.KL-6 can be used as a serological indicator for diagnosis of the PM/DM with ILD,while detections of the serum KL-6 can be used to identify PM/DM with lung disease types,ILD or lung infection.2.Serum KL-6 tests can reflect the damage of the PM/DM patients' pulmonary function.3.Detections of KL-6 levels can be used to evaluate therapeutic effect for the PM/DM with ILD patients.4.High levels of serum KL-6 suggest poor prognosises. |
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