KL-6 as a Biomarker of Interstitial Lung Disease Development in Patients with Sjögren Syndrome: A Retrospective Case–Control Study

Abstract

Objective Krebs von den Lungen-6 (KL-6) is expressed on regenerating type II pneumocytes and has been recognized as biomarkers in interstitial lung disease (ILD). We aim to identify the role of the serum KL-6 level in patients with newly diagnosed Sjögren syndrome (SS), as well as the correlation between the immunoassays. Methods Patients with newly diagnosed SS and receiving HRCT for clinical reason during follow-up were included. Baseline KL-6 level was measured via enzyme-linked immunosorbent assay (ELISA) and latex particle-enhanced turbidimetric immunoassay (LETIA). Results Of the 39 patients, 21 (53.85%) developed interstitial lung disease (ILD) by the conclusion of the follow-up period. The median time to diagnosis of ILD was 2.24 years (IQR 1.15–4.34) in the ILD group. The median serum KL-6 level, measured using ELISA, was 1232 U/mL (IQR 937–2242) and 764.5 U/mL (IQR 503.25–1035.75) in the ILD group and the non-ILD group, respectively (p = 0.001). The median LETIA for serum KL-6 was 329 U/mL (IQR 235–619) and 245 U/mL (IQR 215.25–291) in the ILD group and the non-ILD group, respectively (p = 0.074). Conclusion Serum KL-6 levels were higher in newly diagnosed SS patients with ILD diagnosis during follow-up. Thus, the serum KL-6 level can serve as a valuable biomarker to identify hidden ILD in patients with newly diagnosed SS patients. However, the immunoassay procedure may influence the efficacy of the prediction and its clinical association.

Post-COVID-19 pulmonary fibrosis: An ongoing concern

“…[ 26 ] Other biological markers like KL6 have been heavily investigated as a marker of fibrotic lung disease and an indicator of disease progression and prediction of the risk of exacerbation and prognosis as well. [ 27 28 29 30 ] Xue, and his colleges examined the effect of KL-6 on predicting the development of post COVID-19 pulmonary fibrosis. [ 31 ] This study included 289 patients admitted to the hospital with moderate or severe COVID-19.…”

Serum Osteopontin, KL-6, and Syndecan-4 as Potential Biomarkers in the Diagnosis of Coal Workers’ Pneumoconiosis: A Case–Control Study

“… 15 KL-6 also acts as a chemokine for human fibroblasts, and high concentrations of KL-6 were found in epithelial lining fluid to trigger intra-alveolar fibrosis. 16 KL-6, as a marker, has potential value in the clinical evaluation of ILD. 15 , 17 …”

“…15 KL-6 also acts as a chemokine for human fibroblasts, and high concentrations of KL-6 were found in epithelial lining fluid to trigger intra-alveolar fibrosis. 16 KL-6, as a marker, has potential value in the clinical evaluation of ILD. 15,17 Syndecan-4, a member of the transmembrane heparin sulfate proteoglycan family, binds to extracellular effector molecules and regulates cellular processes such as tissue homeostasis, inflammation, fibrosis, and tumor metastasis.…”

Evaluation of the Clinical Value of KL-6 and Tumor Markers in Primary Sjögren’s Syndrome Complicated with Interstitial Lung Disease

“…KL-6 with predictive value could predict who was more likely to develop progressive fibrosis and reflect some of the adverse consequences of ILD [5]. Serum KL-6 levels can reflect the severity of the alveolar epithelial injury, and the role of KL-6 as a biomarker for ILD has been reported [6]. Our group conducted a multicenter study previously in three leading hospitals of ILD in China and determined the diagnostic and prognostic values of serum KL-6 levels in Chinese patients with ILD.…”