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

Serum YKL-40 and Serum Krebs von den Lungen-6 as Potential Predictive Biomarkers for Rheumatoid Arthritis-Associated Interstitial Lung Disease

BACKGROUND

Interstitial lung disease (ILD) is a common pulmonary manifestation of rheumatoid arthritis (RA) and is associated with a poor prognosis. However, the role of blood biomarkers in RA-associated interstitial lung disease (RA-ILD) is ill-defined. We aim to evaluate the role of YKL-40 and Krebs von den Lungen-6 (KL-6) in the diagnosis and severity evaluation of RA-ILD.

METHODS

45 RA-non-ILD patients and 38 RA-ILD patients were included. The clinical data and the levels of YKL-40 and KL-6 were measured and collected for all patients. The risk factors for RA-ILD were analyzed and their correlation with relevant indicators and predictive value for RA-ILD was explored.

RESULTS

The levels of YKL-40 and KL-6 in RA-ILD patients were higher than RA-non-ILD patients (p < .001). Both YKL-40 and KL-6 were correlated with the incidence of RA-ILD. The predictive power of combined KL-6 and YKL-40 for the presence of ILD was 0.789, with a sensitivity and specificity at 73.7% and 73.3%, respectively. In RA-ILD patients, both YKL-40 and KL-6 were positively correlated with the Scleroderma Lung Study (SLS) I score and negatively correlated with pulmonary function.

CONCLUSIONS

KL-6 and YKL-40 might be a useful biomarker in the diagnosis and severity evaluation of RA-ILD.

Clinical characteristics and outcome of lung cancer in patients with fibrosing interstitial lung disease

BACKGROUND

Lung cancer (LC) is an important comorbidity of interstitial lung disease (ILD) and has a poor prognosis. The clinical characteristics and outcome of each ILD subtype in LC patients have not been sufficiently investigated. Therefore, this study aimed to evaluate the difference between idiopathic pulmonary fibrosis (IPF) and non-IPF ILD as well as prognostic factors in patients with ILD-LC.

METHODS

The medical records of 163 patients diagnosed with ILD-LC at Asan Medical Center from January 2018 to May 2023 were retrospectively reviewed. Baseline characteristics and clinical outcomes were compared between the IPF-LC and non-IPF ILD-LC groups, and prognostic factors were analyzed using the Cox proportional-hazard model.

RESULTS

The median follow-up period was 11 months after the cancer diagnosis. No statistically significant differences were observed in clinical characteristics and mortality rates (median survival: 26 vs. 20 months, p = 0.530) between the groups. The independent prognostic factors in patients with ILD-LC were higher level of Krebs von den Lungen-6 (≥ 1000 U/mL, hazard ratio [HR] 1.970, 95% confidence interval [CI] 1.026-3.783, p = 0.025) and advanced clinical stage of LC (compared with stage I, HR 3.876 for stage II, p = 0.025, HR 5.092 for stage III, p = 0.002, and HR 5.626 for stage IV, p = 0.002). In terms of treatment, surgery was the significant factor for survival (HR 0.235; 95% CI 0.106-0.520; p < 0.001).

CONCLUSIONS

No survival difference was observed between IPF-LC and non-IPF ILD-LC patients. A higher level of Krebs von den Lungen-6 may act as a prognostic marker in ILD-LC patients.

Role of BAL and Serum Krebs von den Lungen-6 (KL-6) in Patients with Pulmonary Fibrosis

Background: Interstitial lung diseases (ILDs) encompass a diverse group of disorders affecting the lung interstitium, leading to inflammation, fibrosis, and impaired respiratory function. Currently, the identification of new diagnostic and prognostic biomarkers for ILDs turns out to be necessary. Several studies show the role of KL-6 in various types of interstitial lung disease and suggest that serum KL-6 levels can be used as a prognostic marker of disease. The aim of this study was to analyze KL-6 expression either in serum or bronchoalveolar lavage samples in order to: (i) make a serum vs. BAL comparison; (ii) better understand the local behavior of fibrosis vs. the systemic one; and (iii) evaluate any differences in patients with progressive fibrosis (PPF) versus patients with non-progressive fibrosis (nPPF). Methods: We used qRT-PCR to detect KL-6 expression both in serum and BAL samples. Mann-Whitney's U test was used to compare the differential expression between groups. Results: In serum, KL-6 is more highly expressed in PPF than in non-progressive fibrosis (p = 0.0295). This difference is even more significant in BAL (p < 0.001). Therefore, it is clear that KL-6 values are related to disease progression. Significant differences were found by making a comparison between BAL and serum. KL-6 was markedly higher in serum than BAL (p = 0.0146). Conclusions: This study identifies KL-6 as a promising biomarker for the severity of the fibrosing process and disease progression in ILDs, with significantly higher levels observed in PPF compared to nPPF. Moreover, the marked difference in KL-6 levels between serum and BAL emphasizes its potential diagnostic and prognostic relevance, providing enlightening insights into both the local and systemic aspects of ILDs.

Expression and significance of serum KL-6 in patients with acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is a common and serious complication that occurs in the ICU. the determination of early ARDS indicators, along with timely treatment, can potentially diminish medical costs and reduce ARDS-related mortality. In this report, we evaluated the clinical significance of circulating Krebs von den Lungen-6 (KL-6) content among patients with intra- and extrapulmonary ARDS to investigate the clinical significance of serum KL-6.

Methods

Patients who met the ARDS Berlin criteria and were hospitalized in the intensive care unit of the China-Japan Union Hospital of Jilin University between September 2021 and September 2022 were recruited for analysis. ARDS patients were divided into an intrapulmonary ARDS group (n=23) and an extrapulmonary ARDS group (n=27) based on their primary diagnosis. Baseline demographic data, including age and sex, and clinical data, including underlying diseases and mortality, of the two groups were collected and analyzed. Peripheral venous blood was collected on Day 0 (baseline), Day 1, Day 3, and Day 7. The kinetic levels of serum KL-6 were compared between patients who survived and those who died within one week of ARDS diagnosis. The prognosis, survival times, and status of patients within 28 days after diagnosis were evaluated.

Results

In the intrapulmonary ARDS group, patients who died had significantly higher serum KL-6 levels in the seven days following diagnosis than those who survived. In contrast, in the extrapulmonary group, the difference in KL-6 values between patients who survived and died was only significant on the first day after diagnosis. The peak levels of serum KL-6 in the death group were significantly higher than those in the survival group for both intra- and extrapulmonary ARDS (P=0.0253). The optimal cutoff value of the serum KL-6 level was 1,452.3 U/mL in intrapulmonary ARDS patients and 828.2 U/mL in extrapulmonary patients. Serum KL-6 levels higher than the cutoff levels were confirmed to be a significant prognostic predictor of poor survival within 28 days of diagnosis in patients with intra- and extrapulmonary ARDS.

Conclusions

The serum KL-6 level is potentially a good indicator for predicting the prognosis of patients with ARDS.

Exploring the Role of Biomarkers Associated with Alveolar Damage and Dysfunction in Idiopathic Pulmonary Fibrosis-A Systematic Review

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is one of the most aggressive forms of interstitial lung diseases (ILDs), marked by an ongoing, chronic fibrotic process within the lung tissue. IPF leads to an irreversible deterioration of lung function, ultimately resulting in an increased mortality rate. Therefore, the focus has shifted towards the biomarkers that might contribute to the early diagnosis, risk assessment, prognosis, and tracking of the treatment progress, including those associated with epithelial injury.

METHODS

We conducted this review through a systematic search of the relevant literature using established databases such as PubMed, Scopus, and Web of Science. Selected articles were assessed, with data extracted and synthesized to provide an overview of the current understanding of the existing biomarkers for IPF.

RESULTS

Signs of epithelial cell damage hold promise as relevant biomarkers for IPF, consequently offering valuable support in its clinical care. Their global and standardized utilization remains limited due to a lack of comprehensive information of their implications in IPF.

CONCLUSIONS

Recognizing the aggressive nature of IPF among interstitial lung diseases and its profound impact on lung function and mortality, the exploration of biomarkers becomes pivotal for early diagnosis, risk assessment, prognostic evaluation, and therapy monitoring.

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

OBJECTIVE

primary Sjögren's syndrome (pSS) is an autoimmune disease, of which the most common complication is interstitial lung disease (ILD). This study aimed to analyze the clinical value of Krebs von den Lungen-6 (KL-6), carcinoembryonic antigen (CEA), and carbohydrate antigen 153(CA153) in patients with pSS complicated with ILD (pSS-ILD), given that only few studies have evaluated this.

METHODS

This is a cross-sectional study. Serum KL-6 levels (U/mL) were measured using chemiluminescence immunoassay, and concentrations of serum tumor markers were determined using the immunofluorescence method in 64 cases of pSS-ILD (pSS-ILD group), 23 cases without ILD (non-ILD group), and 45 healthy controls. The correlation between KL-6 and tumor markers as well as lung function was analyzed, and the factors that were associated with pSS-ILD were screened.

RESULTS

The serum KL-6 was more abnormally increased in patients with pSS-ILD, and the serum KL-6, CEA, carbohydrate antigen 125 (CA125), and CA153 levels were significantly higher in the pSS-ILD group than in the non-ILD and healthy control groups (p < 0.05). KL-6, CEA, and CA153 were negatively correlated with forced vital capacity (FVC%), forced expiratory volume in 1 s (FEV1%), total lung capacity (TLC%), and diffusing capacity for carbon monoxide (DLCO%) (all p < 0.05). Multivariate logistic analysis showed that KL-6 was an independent factor associated with pSS-ILD.

CONCLUSIONS

In conclusion, we evaluated the association between clinical values of KL-6, tumor markers, and pSS-ILD, and found that KL-6 and tumor markers such as CEA, CA153, and CA125 in patients with pSS-ILD were higher than in patients with non-ILD, and KL-6 was more abnormally increased and significantly associated with ILD development in patients with pSS.

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

Background

Coal worker's pneumoconiosis (CWP) is a chronic occupational disease mainly caused by coal dust inhalation in miners. This study aimed to investigate the clinical value of Osteopontin (OPN), KL-6, Syndecan-4 and Gremlin-1 as serum biomarkers in CWP.

Patients and Methods

We integrated reported lung tissues transcriptome data in pneumoconiosis patients with silica-exposed alveolar macrophage microarray data to identify four CWP-associated serum biomarkers. The serum concentrations of Osteopontin, Krebs von den Lungen-6 (KL-6), Syndecan-4 and Gremlin-1 were measured in 100 healthy controls (HCs), 100 dust-exposed workers (DEWs) and 200 patients of CWP. Receiver operating characteristic (ROC) curve analysis was used to determine the sensitivity, specificity, cut-off value and area under the curve (AUC) value of biomarkers.

Results

The pulmonary function parameters decreased sequentially, and the serum OPN, KL-6, Syndecan-4 and Gremlin-1 concentrations were increased sequentially among the HC, DEW and CWP groups. Among all participants, multivariable analysis revealed that these four biomarkers were negatively correlated with the pulmonary function parameters (all p<0.05). Compared with HCs, patients with higher OPN, KL-6, Syndecan-4 and Gremlin-1 had higher risk for CWP. The combination of OPN, KL-6, and Syndecan-4 can improve the diagnostic sensitivity and specificity of CWP patients differentiated from HCs or DEWs.

Conclusion

OPN, KL-6 and Syndecan-4 are novel biomarkers that can be used for CWP auxiliary diagnosis. The combination of three biomarkers can improve the diagnostic values of CWP.

Krebs von den Lungen-6 (KL-6) as a diagnostic marker for pulmonary fibrosis: A systematic review and meta-analysis

BACKGROUND

Pulmonary fibrosis (PF) is a respiratory disease with end-stage pathological changes of interstitial lung disease that severely affects the survival of patients. Among the many biomarkers that have been identified, serum Krebs von den Lungen-6 (KL-6) is by far the most frequent marker for detecting pulmonary fibrosis.

METHODS

We searched Medline (Pubmed), Embase, Web of science, and Cochrane databases for articles published between inception and August 2022 in order to explore the association between KL-6 and pulmonary fibrosis. Characteristics of patients and studies included in the articles were extracted by two independent investigators according to the inclusion and exclusion criteria. We reflected the accuracy of KL-6 in distinguishing between PF and non-PF by calculating sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and area under the curve by SROC curves. The presence of heterogeneity was reflected by I² in the forest plot, and then the source of heterogeneity was investigated by meta-regression.

RESULTS

We searched for 939 research papers, of which 16 met the inclusion criteria. Meta-analysis showed a sensitivity of 0.87 (95 % CI: 0.78-0.92), specificity of 0.91 (95 % CI: 0.86-0.95), positive likelihood ratio of 10.2 (95 % CI: 6.1, 17.0) and negative likelihood ratio of 0.14 (95 % CI: 0.08, 0.25) for KL-6 in diagnosing pulmonary fibrosis. The area under the receiver operating characteristic curve was 0.95 (95 % CI: 0.93-0.97). The results showed significant heterogeneity in both sensitivity and specificity (I² = 94.55 and 91.52, respectively). Meta-regression analysis identified race as the cause of sensitivity heterogeneity and assay methodology as the cause of specificity heterogeneity.

CONCLUSIONS

The analysis of this study suggests that serum KL-6 is a better tool for the diagnosis of pulmonary fibrosis when factors such as disease cause and control group category are not specifically considered.

Serum lactate dehydrogenase is associated with impaired lung function: NHANES 2011-2012

BACKGROUND

Serum lactate dehydrogenase levels reflect disease status in a variety of organs, but its role in indicating pulmonary function is not yet clear. Therefore, this study explored the correlation between pulmonary function and serum lactate dehydrogenase, and investigated thresholds for changes in pulmonary function indicators in the total population as well as in different strata of the population.

METHODS

Based on data from the National Health and Nutrition Examination Survey (NHANES) 2011-2012 (n = 3453), univariate and stratified analyses were performed to investigate factors associated with pulmonary function, and multiple regression analysis was used to further investigate the specific relationship with serum lactate dehydrogenase. Smoothed curve fitting, threshold effect and saturation effect analysis were used to explore the threshold level of serum lactate dehydrogenase at the onset of changes in pulmonary function indicators.

RESULTS

Adjusted smoothed curve fit plots showed a linear relationship between serum lactate dehydrogenase levels and forced vital capacity and forced expiratory volume in one second: for each 1 U/L increase in serum lactate dehydrogenase levels, forced vital capacity decreased by 1.24 mL (95% CI = -2.05, -0.42, P = 0.0030) and forced expiratory volume in one second by 1.11 mL (95% CI = -1.82, -0.39, P = 0.0025).

CONCLUSIONS

Serum lactate dehydrogenase was negatively and linearly correlated with pulmonary function indices in the total population analyzed. Based on the total population and different population stratifications, this study determined the threshold values of serum lactate dehydrogenase at the onset of decline of pulmonary function in different populations. This provides a new serological monitoring indicator for patients suffering from respiratory diseases and has implications for patients with possible clinical impairment of pulmonary function. However, our cross-sectional study was not able to determine a causal relationship between these two factors, and further research is needed.

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.

Blood Krebs von den Lungen-6 levels predict treatment response to antifibrotic therapy in patients with idiopathic pulmonary fibrosis

BACKGROUND

Antifibrotic therapy can slow disease progression (DP) in patients with idiopathic pulmonary fibrosis (IPF). However, the prognostic biomarkers for DP in patients with IPF receiving antifibrotic therapy have not been identified. Therefore, we aimed to evaluate the prognostic efficacy of serum Krebs von den Lungen-6 (KL-6) for DP in patients with IPF receiving antifibrotic therapy.

METHODS

The clinical data of 188 patients with IPF who initiated antifibrotic therapy at three tertiary hospitals was retrospectively analyzed. DP was defined as a relative decline in forced vital capacity (FVC) ≥ 10%, diffusing capacity for carbon monoxide ≥ 15%, acute exacerbation, or deaths during 6 months after antifibrotic therapy.

RESULTS

The mean age of patients was 68.9 years, 77.7% were male, and DP occurred in 43 patients (22.9%) during follow-up (median, 7.6 months; interquartile range, 6.2-9.8 months). There was no difference in baseline KL-6 levels between the DP and no-DP groups; however, among patients with high baseline KL-6 levels (≥ 500 U/mL), changes in KL-6 levels over 1 month were higher in the DP group than those in the non-DP group, and higher relative changes in KL-6 over 1 month were independently associated with DP (odds ratio, 1.043; 95% confidence interval 1.005-1.084) in the multivariable logistic analysis adjusted for age and FVC. In the receiver operating characteristic curve analysis, the 1-month change in KL-6 was also useful for predicting DP (area under the curve = 0.707; P < 0.012).

CONCLUSIONS

Our data suggest that the relative change in KL-6 over 1 month might be useful for predicting DP in patients with IPF receiving antifibrotic therapy when baseline KL6 is high.