Expression Levels And Clinical Significance Of KL-6,IL-18,and S100A8/A9 In The Serum Of Patients With Connective Tissue Disease Associated Interstitial Lung Disease

Objectives:To explore the correlation between KL-6,IL-18,S100A8/A9 and the diagnosis and disease severity of connective tissue disease associated interstitial lung disease(CTD-ILD)by detecting the level of serum KL-6,IL-18,S100A8/A9 in patients with CTD-ILD Methods:Data were collected from 30 health examination subjects(HC group),30 patients with connective tissue disease without interstitial lung disease(CTD group)and 33 patients with connective tissue disease associated interstitial lung disease(CTD-ILD group).According to the severity of the disease assessed by lung function examination,the CTD-ILD group was divided into 4 subgroups(normal,mild,moderate and severe).The expression levels of serum KL-6,IL-18 and S100A8/A9 in each group were detected by Enzyme-linked Immunosorbent Assay(ELISA).Pulmonary function examination was used to assess the severity of the disease,and general clinical data and related laboratory test results of the above subjects were collected.SPSS 20.0 statistical software was used for data analysis.Results:Serum levels of KL-6,IL-18,S100A8/A9 in CTD-ILD group were higher than those in CTD group and HC group,and the difference was statistically significant(P< 0.05).The CTD-ILD group was divided into four subgroups(normal,mild,moderate,severe)according to the severity of the disease.The results showed that the more serious the disease was,the higher the serum KL-6 level was.There were no significant differences in serum IL-18 and S100A8/A9 levels among subgroups(P >0.05).Serum KL-6 level was negatively correlated with FVC% and DLCO% of lung function in CTD-ILD group(r =-0.413,P =0.017;r =-0.402,P =0.023),while IL-18,S100A8/A9 had no significant correlation with FVC% and DLCO%(P > 0.05).The optimal cut-off value for KL-6 to diagnose CTD-ILD was 4.73ng/ml(sensitivity: 89%,specificity: 62.3%,P < 0.05),the optimal cut-off value of IL-18 in the diagnosis of CTD-ILD was 294.07pg/ml(sensitivity: 87.9%,specificity: 83.6%,P < 0.05),the optimal cut-off value of S100A8/A9 for the diagnosis of CTD-ILD was303.77ng/ml(sensitivity: 97%,specificity: 70.5%,P < 0.05).The sensitivity and specificity of serum KL-6,IL-18 and S100A8/A9 in the diagnosis of CTD-ILD were87.9% and 95.1%.The combined detection of three markers can improve the diagnostic specificity.Conclusions:The detection of serum KL-6,IL-18,and S100A8/A9 has important value in the diagnosis of CTD-ILD.The combined detection of serum KL-6,IL-18 and S100A8/A9 can improve the specificity of diagnosis.Serum KL-6 is associated with the severity of the disease in CTD-ILD.The more serious the disease,the higher the serum level of KL-6,which may indicate a poor prognosis.