Salivate glycogen-6 expression and clinical significance in children with interstitial lung disease
Authors: Li Hongwei , Wu Shangzhi , Huang Kaiyin , Lin Yuneng , Tang Sixiang , Xu Jiaxing , Huang Zhanhang , Chen Dehui 
Published: November 2023

Abstract
Objective Aim of this study is to find the correlation of clinical symptom severity score, lung HRCT score and lung function index with serum KL-6 level in children with ILD was analyzed, and the clinical significance of serum KL-6 expression level in children with ILD was discussed. Method In this study, 81 ILD children admitted to the Department of General Pediatrics of the First Affiliated Hospital of Guangzhou Medical University from January 2015 to December 2022 who had not been treated with systemic hormone therapy were selected as ILD group.A total of 85 age-matched children with community-acquired pneumonia who were hospitalized during the same period were selected as the control group. And 20 healthy children were used as normal control group.Analysing the correlation of clinical symptom severity score, lung HRCT score and lung function index with serum KL-6 level in children with ILD was analyzed, and the clinical significance of serum KL-6 expression level in children with ILD. Results Comparison of baseline data of children in the three groups :A total of 81 ILD children from January 2015 to December 2022, including 41 males and 40 females, aged 5.77 ± 3.51 years.The family history of connective tissue disease in ILD group (6.2%) was higher than that in disease control group and control group (0%) (p < 0.05).Compared with disease control group and control group, peripheral blood WBC > 10×109/L, peripheral NEUT% level and blood gas analysis PaCO2 were significantly increased, peripheral Hb level and blood gas analysis PaO2 were significantly decreased in ILD group, and the differences were significant (all p < 0.05). According to the pulmonary HRCT scoring criteria, the 81 children were evaluated with pulmonary HRCT scores. The maximum total HRCT score was 96 points, the median HRCT score of the 81 children was 15 (10,23) points, and the maximum HRCT score was 51 points.The median HRCT score of 85 children in the control group was 1 (0,2), and the maximum score was 10. The HRCT scores of 20 children in the control group were all 0 points.There were 40 children who could complete the pulmonary ventilation function examination, including 20 males and 20 females, aged 8.55 (6.00,9.30) years. The pulmonary ventilation function test results of 40 children were as follows: FVC%pred was 77.40 (57.25, 92.37) %, VC%pred was 83.04 (51.48, 90.20) %, FEV1%pred was 78.42 (59.15, 98.35) %, FEV1/FVCwas104.39 (99.93, 108.72) % .The level of serum KL-6 expression in ILD group was significantly higher than that in disease control group and control group, and the difference was statistically significant (p < 0.05). the best cut-off value for the diagnosis of ILD in children with serum KL-6 was 393.5U/ml, and the sensitivity and specificity were 77.8% and 98.1% respectively.Spearman correlation analysis showed that serum KL-6 concentration was positively correlated with clinical symptom severity score (r = 0.751, p < 0.01), and lung HRCT score was positively correlated (r = 0.405, p < 0.01). Serum KL-6 concentration was significantly higher than that of FVC%pred(r=-0.575, p < 0.01), VC%pred(r=-0.705, p < 0.01), FEV1%pred (r=-0.525, P < 0.01), DLCO% pred(r= -0.467, P < 0.01), respectively. p = 0.016) were negatively correlated with FEV1/FVC (p > 0.05). Conclusion The level of serum KL-6 in ILD children was significantly higher than that in disease control group and control group. Serum KL-6 can be used as a biomarker for the clinical diagnosis of ILD in children.Serum KL-6 expression level in ILD children was positively correlated with clinical symptom severity score and HRCT score, and negatively correlated with lung function indexes FVC%pred, VC%pred, FEV1%pred and DLCO%pred. Serum KL-6 expression level could be used as one of the observation indexes of disease severity.