Serum KL-6 Elevation and Possible Pulmonary Involvement in Patients with Rheumatoid Arthritis Treated with Biological Agents

Expression of S100A9 and KL-6 in common interstitial lung diseases

By evaluating S100 calcium binding protein A9 (S100A9) and Klebs von den Lungen-6 (KL-6) expression in patients with 4 common interstitial lung diseases (ILDs), we aimed to investigate whether S100A9 or KL-6 can be of any value in the differential diagnosis of these ILDs and simultaneously signal the disease progression.We collected the data of patients diagnosed with the 4 ILDs and underwent fiber-optic bronchoscopy and BAL in the First Affiliated Hospital, China Medical University from January 2012 to December 2020. The data related to BGA, C-reactive protein, pulmonary function test, total number and fraction of cells, T lymphocyte subsets in bronchoalveolar lavage fluid (BALF), and the expression of S100A9 and KL-6 in BALF and serum were collected. We analyzed, whether S100A9 or KL-6 could serve as a biomarker for differential diagnosis between the 4 common ILDs; whether the levels of S100A9 and KL-6 correlated with each other; whether they were correlated with other clinical parameters and disease severity.This study included 98 patients, 37 patients with idiopathic pulmonary fibrosis (IPF), 12 with hypersensitivity pneumonitis, 13 with connective tissue disease-associated ILD, and 36 with sarcoidosis (SAR): stage I (18), stage II (9), stage III (5), and stage IV (4). The expression of KL-6 in BALF was significantly higher in IPF patients than other 3 groups (all P-value < .05). However, there was no significant difference in the levels of S100A9 in BALF and serum between the 4 groups (P-value > .05). The levels of S100A9 in BALF of IPF patients was positively and significantly correlated with KL-6 expression and the percentage of neutrophils in BALF (P-value < .05). Along with the stage increase of SAR patients, the level of S100A9 in BALF gradually increased, which was negatively and significantly correlated with the forced vital capacity/predicted, carbon monoxide diffusing capacity/predicted%, and PaO2 (all P-value < .05).The expression of KL-6 in BALF can be used as a biomarker to differentiate IPF from the other 3 common ILDs. While, this was not the case with expression of S100A9 in BALF and serum. However, the expression S100A9 in BALF is useful to indicate the progression of SAR. Thus, simultaneous measurement of KL-6 and S100A9 levels in BALF makes more sense in differential diagnosing of the 4 common ILDS.

Krebs von den Lungen-6 levels in untreated idiopathic pulmonary fibrosis

Background

Serum Krebs von den Lungen‐6 (KL‐6) has been reported to be elevated in patients with idiopathic pulmonary fibrosis (IPF).

Objective

The aim of this study was to evaluate the diagnostic value of KL‐6 and whether the expression value of KL‐6 could indicate the severity of the disease in IPF patients. To address this question, it is necessary to see whether the patients' physical characteristics and other clinical conditions could affect the baseline KL‐6 level.

Design

We conducted a study of 100 patients who were diagnosed with IPF. Lung function, computed tomography (CT), and serological lab tests data were analyzed.

Results

The tests showed that there is a significant elevation of KL‐6 in IPF patients compared with other interstitial lung disease (ILD) and healthy controls. It was noted that serum KL‐6 is a stable biomarker not affected by lung infection and smoking, though IPF patients with antinuclear antibody (ANA) showed higher KL‐6 levels. KL‐6, in conjunction with poor pulmonary function and higher radiological fibrosis scores, indicates the severity of the disease but not poor survival.

Conclusions

It is identified that serum KL‐6 is a useful noninvasive biomarker to help improve the certainty of IPF diagnosis from other interstitial lung disease and assist evaluation of disease severity and prognosis.

Serum KL-6, CA19-9, CA125 and CEA are Diagnostic Biomarkers for Rheumatoid Arthritis-Associated Interstitial Lung Disease in the Chinese Population

Introduction

This study aimed to evaluate the role of tumor marker carbohydrate antigen (CA) 125 (CA125), CA19-9, carcinoembryonic antigen (CEA) and Krebs von den Lungen-6 (KL-6) in the diagnosis and determination of the severity of interstitial lung disease (ILD) in rheumatoid arthritis (RA) patients.

Methods

A retrospective analysis was performed. Fifty RA patients (24 patients with ILD and 26 patients without ILD), 10 healthy subjects and 14 patients with other connective tissue disease-associated interstitial lung disease were included. Serum levels of KL-6 and tumor markers CA19-9, CA125 and CEA were measured. Chest HRCT of patients with ILD was scored quantitatively according to the degree of fibrosis. Data on the C-reactive protein, erythrocyte sedimentation rate, rheumatoid factors and anti-cyclic peptide containing citrulline (anti-CCP) were also collected.

Results

Serum levels of KL-6, CA19-9, CA125 and CEA in the RA-ILD group were significantly higher than those in the RA-no-ILD group. The serum KL-6 level was positively correlated with the HRCT fibrosis score (r = 0.63, p = 0.002). The logistic regression analysis showed that CA19-9 and smoking were associated with RA-ILD [OR = 1.118, 95% CI = (1.038, 1.204), p = 0.003 for CA19-9, OR = 14.969, 95% CI = (1.750, 128.043), p = 0.013 for smoking].

Conclusions

KL-6 level and tumor markers were elevated in RA-ILD, and strongly associated with the severity of ILD, supporting their value as pathogenically relevant biomarkers, which can contribute to noninvasive detection of this extra-articular disease complication.

Interstitial lung disease (ILD) is a common pulmonary manifestation of RA associated with high morbidity and mortality. Our retrospective study was performed to investigate the clinical utility of tumor marker carbohydrate antigen (CA) 125 (CA125), CA19-9, carcinoembryonic antigen (CEA) and Krebs von den Lungen-6 (KL-6) in the diagnosis and determining the severity of RA-ILD. Fifty RA patients (24 patients with ILD and 26 patients without ILD), 10 healthy subjects and 14 patients with other connective tissue disease-associated interstitial lung disease (CTD-ILD) were included. The results showed KL-6 level and tumor markers were elevated in RA-ILD, and strongly associated with the severity of ILD, which meant KL-6 and tumor markers might be useful pathogenically relevant biomarkers and could be predictors for the diagnosis and determination of severity of ILD in RA.

Serum Krebs von den Lungen-6 levels in psoriatic patients under treatment with biologics

During biologic treatments, attention should be paid to adverse reactions, particularly infectious diseases. Furthermore, drug-induced interstitial lung disease is also known to be associated with biologic therapies. We retrospectively reviewed serum Krebs von den Lungen-6 (KL-6) levels in psoriatic patients who underwent treatment with seven different biologics. A total of 67 patients who received 80 biologic treatments were evaluated. The 31 anti-tumor necrosis factor (TNF)-α treatments consisted of 17 infliximab (IFX) and 14 adalimumab. The 23 anti-interleukin (IL)-23 treatments consisted of 14 ustekinumab and nine guselkumab. The 26 anti-IL-17 treatments consisted of nine secukinumab, six ixekizumab and 11 brodalumab. The IFX showed significantly increased mean serum KL-6 (170.9%), but none of the other treatments showed significant increases. Thirteen of the 17 (75.6%) patients in the IFX and 17 of the 31 (54.8%) patients in the total anti-TNF-α group demonstrated at least a 25% increase in serum KL-6. Levels exceeding the cut-off (500 U/mL) were detected in three patients before treatment and in seven patients after treatment. This study showed that anti-IL-17 and anti-IL-23 treatments have no significant impact on serum KL-6 level. In addition to the influence of IFX, a significantly large number of patients in the IFX group had a history of methotrexate administration associated with psoriatic arthritis, which might have influenced the KL-6 level. None of the patients with elevated serum KL-6 showed pulmonary changes by computed tomography and/or X ray.

Treatment of Rheumatoid Arthritis-Associated Interstitial Lung Disease: Lights and Shadows

Rheumatoid arthritis (RA) is a chronic and systemic inflammatory disease affecting 0.5–1% of the population worldwide. Interstitial lung disease (ILD) is a serious pulmonary complication of RA and it is responsible for 10–20% of mortality, with a mean survival of 5–8 years. However, nowadays there are no therapeutic recommendations for the treatment of RA-ILD. Therapeutic options for RA-ILD are complicated by the possible pulmonary toxicity of many disease modifying anti-rheumatic drugs (DMARDs) and by their unclear efficacy on pulmonary disease. Therefore, joint and lung involvement should be evaluated independently of each other for treatment purposes. On the other hand, some similarities between RA-ILD and idiopathic pulmonary fibrosis and the results of the recent INBIULD trial suggest a possible future role for antifibrotic agents. From this perspective, we review the current literature describing the pulmonary effects of drugs (immunosuppressants, conventional, biological and target synthetic DMARDs and antifibrotic agents) in patients with RA and ILD. In addition, we suggest a framework for the management of RA-ILD patients and outline a research agenda to fill the gaps in knowledge about this challenging patient cohort.

Serum KL-6 elevation in a uveitis patient with Behçet's disease treated with adalimumab

Purpose

To report a case of uveitis with Behçet's disease in which serum levels of Krebs von den Lungen (KL)-6, a marker of interstitial lung disease, were elevated during treatment with adalimumab and returned to baseline after discontinuation of the agent.

Observations

A 67-year-old man complaining of vision disturbance was referred to our hospital. The patient had a history of recurrent episodes of bilateral uveitis and oral ulcers, and had been diagnosed with Behçet's disease. While uveitis activity was not well controlled under administration of oral prednisolone and cyclosporin, cataract of the right eye developed and required surgery. Biweekly administration of adalimumab 40 mg was therefore initiated with prednisolone at 15 mg/day. Uveitis became well controlled and cataract surgery was successfully carried out for the right eye. However, serum KL-6 gradually elevated to 1002 U/ml by 6 months after adalimumab initiation and 1277 U/ml at 9 months. Because serum KL-6 >1000 U/ml has been reported to predict interstitial lung disease, we discontinued adalimumab and started cyclosporine at 100 mg/day. Serum KL-6 gradually decreased and returned to baseline levels, no interstitial lung disease developed and exacerbation of uveitis was avoided.

Conclusions and importance

This case implies the clinical importance of monitoring serum KL-6 in patents with non-infectious uveitis being treated with adalimumab.

A Patient with KL-6 Elevation with Anti-TNFα Who Could Receive Long-Term Use without Interstitial Pneumonia after Class Switch of Anti-TNFα

A 40-year-old man with refractory ulcerative colitis (UC) was treated with tumor necrosis factor α inhibitor (anti-TNFα), infliximab. One month later, the chest computed tomography and laboratory test showed noninfectious interstitial lung disease (ILD) and elevation of serum Krebs von den Lungen-6 (KL-6). Fortunately, ILD disappeared after the discontinuation with anti-TNFα. Two and a half years after his first UC treatment, he was treated again with another anti-TNFα, adalimumab, for relapse and he had a second ILD. This course suggested anti-TNFα induced ILD. The characteristics of anti-TNFα-induced ILD in inflammatory bowel disease (IBD) are not well understood. We summarized and investigated the characteristics of such patients based on a literature review including 15 cases. It suggested that anti-TNFα-induced ILD in IBD might be rare and tends to have a better outcome compared with ILD in rheumatoid arthritis.

Biologics-induced interstitial lung diseases in rheumatic patients: facts and controversies

INTRODUCTION

Interstitial lung disease (ILD) is a common, devastating pulmonary complication. An increased number of reports suggesting that biological disease modifying antirheumatic drugs (DMARDs) induced or exacerbated ILDs in rheumatoid arthritis (RA) patients has garnered increased attention. Areas covered: This article discusses ILDs induced by or exacerbated during biological therapy in RA patients. The article summarizes the efficacy and safety of a variety of licensed and off-label biologics clinically used for rheumatic diseases, focusing on the onset or exacerbation of RA-associated ILDs (RA-ILDs) in RA patients treated with biologics targeting tumor necrosis factor, CD20, interleukin 1 (IL-1) and IL-6 receptors. Additionally, the pathogenesis of RA-ILDs is discussed. Expert opinion: To some extent, the possibility of biologic-induced RA-ILDs increases the difficulty in choosing an optimal regimen for RA treatment with biological agents, as the relationship between biological therapy safety and the induction or exacerbation of RA-ILDs has not been established. A framework to assess baseline disease severity, particularly standardizing the evaluation of the pulmonary condition stage in RA patients and monitoring the outcome during the biological therapy treatment, is highly needed and may substantially help guide treatment decisions and predict the treatment benefits.