AB1236 KL-6 AS A BIOMARKER FOR SJÖGREN SYNDROME-ASSOCIATED INTERSTITIAL LUNG DISEASE: METHODOLOGY MATTERS

Background:Krebs von den Lungen-6 (KL-6) was recently found to be a serum biomarker for various disease associated interstitial lung disease (ILD) including primary Sjögren syndrome (pSS).1KL-6 is a high-molecular-weight glycoprotein in the Mucin 1 protein group and is majorly expressed by regenerating type II pneumocytes; hence, serum KL-6 levels may reflect the severity of pulmonary damage with regeneration.2Human KL-6 also promotes the proliferation and survival of pulmonary fibroblasts and the differentiation of myofibroblasts, which enhance fibrosis.3, 4Objectives:To evaluate the agreement between the latex particle-enhanced turbidimetric immunoassay with enzyme-linked immunosorbent assay (ELISA) and association with clinical phenotypes.Methods:This retrospective case-control study included 39 patients with pSS, of whom 21 (53.85%) patients developed ILD at the end of follow-up. The serum KL-6 level was compared between latex particle-enhanced turbidimetric immunoassay (Nanopia) and ELISA (MBS2601395; MyBioSource, CA, USA). Electronic medical records were reviewed, including clinical information, images, pulmonary function test, and laboratory results on inclusion, and a chest physician reviewed the results of pulmonary radiography.Results:The two serum KL-6 immunoassays revealed a moderate correlation with a Pearson product-moment correlation coefficient of 0.427. Serum KL-6 levels, measured using ELISA, were 1920.10 ± 1974.26 U/mL and 894.11 ± 788.53 U/mL in the ILD and non-ILD groups, respectively (p = 0.001). The latex particle-enhanced turbidimetric immunoassay for serum KL-6 was 459.62 ± 331.41 U/mL and 265.33 ± 105.37 U/mL in the ILD and non-ILD group, respectively (p = 0.074). The predictive values of serum KL-6 in the area under the receiver-operating characteristic curve were 0.810 and 0.669 in ELISA and latex particle-enhanced turbidimetric immunoassay, respectively.Conclusion:Serum KL-6 is a predicting biomarker in pSS patients who may develop ILD. However, the methodology of immunoassay may influence the efficacy of the prediction and clinical association.References:[1]Chiu Y-H, Lu C-C, Liu F-C, et al. FRI0228 KL-6 AS A BIOMARKER OF DEVELOPING INTERSTITIAL LUNG DISEASE IN PATIENTS WITH SJÖGREN SYNDROME.Ann Rheum Dis. 2019; 78: 793.[2]Yousefi M, Dehghani S, Nosrati R, et al. Aptasensors as a new sensing technology developed for the detection of MUC1 mucin: A review.Biosensors & bioelectronics. 2019; 130: 1-19.[3]Xu L, Yan DR, Zhu SL, et al. KL-6 regulated the expression of HGF, collagen and myofibroblast differentiation.Eur Rev Med Pharmacol Sci. 2013; 17: 3073-7.[4]Ohshimo S, Yokoyama A, Hattori N, Ishikawa N, Hirasawa Y and Kohno N. KL-6, a human MUC1 mucin, promotes proliferation and survival of lung fibroblasts.Biochem Biophys Res Commun. 2005; 338: 1845-52.Acknowledgments:This work was supported by National Defense Medical Center and Tri-Service General Hospital (TSGH-D-109183). The authors thank Kuo’s Yuan In Enterprise co., LTD for supporting Nanopia KL-6 Kit.Disclosure of Interests:None declared