Novel germline STAT3 gain-of-function mutation causes autoimmune diseases and severe growth failure.

Background: In recent years, germline gain-of-function (GOF) mutations in signal transducer and activator of transcription 3 (STAT3) have been identified as a cause of early-onset multiorgan autoimmune diseases with the widespread use of next-generation sequencing, and targeted therapies such as tocilizumab have been reported to be effective. Objective: We sought to assess whether a novel STAT3 mutation detected by whole-exome sequencing is pathogenic and examine the efficacy of targeted therapy. Methods: A pediatric patient with idiopathic pulmonary hemosiderosis, autoimmune thyroiditis, inflammatory bowel disease unclassified, leukocytosis, thrombocytosis, and severe growth failure was examined. Results: This 7-year-old boy had idiopathic pulmonary hemosiderosis at the age of 6 months. Despite high-dose steroid therapy, pulmonary fibrosis progressed. Furthermore, he presented with severe growth failure, autoimmune thyroiditis, leukocytosis, thrombocytosis, and inflammation bowel disease unclassified. Given the presence of multiple autoimmune diseases, whole-exome sequencing was performed, which detected germline de novo heterozygous STAT3 mutation (NM_139276.2; c.2144C>A, p.(P715Q)). Dual-luciferase reporter assay revealed this novel STAT3 mutation as GOF. After starting tocilizumab therapy at the age of 6, hospital stays decreased, and the progression of pulmonary fibrosis was decelerated without increasing the steroid dose. New autoimmune diseases did not develop, and no apparent adverse effects on growth have been observed. Conclusions: Tocilizumab may be effective for patients with STAT3 GOF mutation, including those requiring long-term management of idiopathic pulmonary hemosiderosis. Diagnosis of patients with early-onset multiorgan autoimmune diseases in which STAT3 GOF is suspected should be confirmed by genetic testing and functional analysis to consider the introduction of targeted therapies.

A nomogram model combining computed tomography-based radiomics and Krebs von den Lungen-6 for identifying low-risk rheumatoid arthritis-associated interstitial lung disease.

Objectives: Quantitatively assess the severity and predict the mortality of interstitial lung disease (ILD) associated with Rheumatoid arthritis (RA) was a challenge for clinicians. This study aimed to construct a radiomics nomogram based on chest computed tomography (CT) imaging by using the ILD-GAP (gender, age, and pulmonary physiology) index system for clinical management. Methods: Chest CT images of patients with RA-ILD were retrospectively analyzed and staged using the ILD-GAP index system. The balanced dataset was then divided into training and testing cohorts at a 7:3 ratio. A clinical factor model was created using demographic and serum analysis data, and a radiomics signature was developed from radiomics features extracted from the CT images. Combined with the radiomics signature and independent clinical factors, a nomogram model was established based on the Rad-score and clinical factors. The model capabilities were measured by operating characteristic curves, calibration curves and decision curves analyses. Results: A total of 177 patients were divided into two groups (Group I, n = 107; Group II, n = 63). Krebs von den Lungen-6, and nineteen radiomics features were used to build the nomogram, which showed favorable calibration and discrimination in the training cohort [AUC, 0.948 (95% CI: 0.910-0.986)] and the testing validation cohort [AUC, 0.923 (95% CI: 0.853-0.993)]. Decision curve analysis demonstrated that the nomogram performed well in terms of clinical usefulness. Conclusion: The CT-based radiomics nomogram model achieved favorable efficacy in predicting low-risk RA-ILD patients.

Serum Krebs von den Lungen-6 as a potential biomarker for distinguishing combined pulmonary fibrosis and emphysema from chronic obstructive pulmonary disease: A retrospective study.

Background: The presence of fibrotic interstitial lung disease (ILD) is relatively common in patients with emphysema. This has been designated combined pulmonary fibrosis and emphysema (CPFE). CPFE had worse prognosis than emphysema alone. Krebs von den Lungen-6 (KL-6) levels as a biomarker of alveolar type 2 epithelial cell injury, which is widely used to identify the presence of ILD, whether it can differentiate CPFE from COPD remains unknown. Methods: 259 patients from Xiangya Hospital with diagnosis of COPD, with or without ILD, and who had KL-6 tests were recruited for this retrospective analysis. Recorded data included demographic information, comorbidities, inflammatory biomarkers. Results of CT and pulmonary function tests were collected one week before or after KL-6 measurements. Results: Among 259 patients, 52 patients were diagnosed with CPFE. The mean age was 67.39 ± 8.14 yeas. CPFE patients had higher ratio of rheumatic diseases (21.2 % vs 7.2 %, P = 0.003). CPFE patients exhibited higher values of FEV1 (1.97 vs 1.57, P = 0.002) and FEV1/FVC ratio (69.46 vs 57.64, P < 0.001) compared to COPD patients. CPFE patients had higher eosinophil counts, percentage of eosinophils, lactate dehydrogenase, total bilirubin levels and lower platelet counts. Serum KL-6 levels were higher in CPFE group compared to COPD group (574.95 vs 339.30 U/mL, P < 0.001). Multiple logistic regression showed that KL-6 level was an independent predictive factor for the presence of ILD among COPD patients. The AUC of serum KL-6 levels to differentiate CPFE was 0.711, with 95 % CI being 0.635 to 0.787. The cutoff point of KL-6 level was 550.95 U/mL with 57.7 % sensitivity and 79.7 % specificity for the discrimination of CPFE from COPD. Conclusion: CPFE patients show higher KL-6 levels compared to isolated COPD, suggesting the potential of KL-6 as a practical screening tool for interstitial lung disease, specifically CPFE. A KL-6 threshold of 550.95 U/mL in COPD patients may indicate a high need for high-resolution chest computed tomography to detect fibrosis.

Diagnostic Value of Serum KL-6 in Interstitial Lung Diseases.

Objective: To explore serum KL-6 level and investigate its diagnostic value in interstitial lung diseases (ILDs). Methods: Serum KL-6 level was measured using the chemiluminescent enzyme immunoassay. Statistical analysis was performed for determining the KL-6 concentration of each group. Results: KL-6 level (U/mL) in the ILD group was 1388.321 ±1943.116, which was higher than that in the control group, showing a significant statistical difference. ROC curve analysis based on the receiver operating characteristic curve showed the optimal cut-off value of 402.5U/mL, sensitivity of 77.4%, specificity of 93.4%, and accuracy of 89.4%; through Chi-square test with the two groups, the positive rate of KL-6 in patients with ILD was proved to be significantly higher than that in the control group. KL-6 level was 1063.00±504.757 in the idiopathic pulmonary fibrosis (IPF) group, 1346.892 ±1827.252 in the connective tissue disease-associated interstitial lung disease (CTD-ILD) group, 467.889±288.859 in the organizing pneumonia (OP) group, 8252.333±6050.625 in the pulmonary alveolar proteinosis (PAP) group, and 359.200±392.707 in the sarcoidosis group. The rank sum test showed that the differences were statistically significant. KL-6 level was the lowest in the sarcoidosis group, followed by that in the OP group. Conclusion: Serum KL-6 level was confirmed to be highly sensitive, specific, and accurate in the diagnosis of ILD. Subgroup analysis showed that the KL-6 level was the lowest in the sarcoidosis group, followed by that in the OP group.

A non-enhanced CT-based deep learning diagnostic system for COVID-19 infection at high risk among lung cancer patients.

Background: Pneumonia and lung cancer have a mutually reinforcing relationship. Lung cancer patients are prone to contracting COVID-19, with poorer prognoses. Additionally, COVID-19 infection can impact anticancer treatments for lung cancer patients. Developing an early diagnostic system for COVID-19 pneumonia can help improve the prognosis of lung cancer patients with COVID-19 infection. Method: This study proposes a neural network for COVID-19 diagnosis based on non-enhanced CT scans, consisting of two 3D convolutional neural networks (CNN) connected in series to form two diagnostic modules. The first diagnostic module classifies COVID-19 pneumonia patients from other pneumonia patients, while the second diagnostic module distinguishes severe COVID-19 patients from ordinary COVID-19 patients. We also analyzed the correlation between the deep learning features of the two diagnostic modules and various laboratory parameters, including KL-6. Result: The first diagnostic module achieved an accuracy of 0.9669 on the training set and 0.8884 on the test set, while the second diagnostic module achieved an accuracy of 0.9722 on the training set and 0.9184 on the test set. Strong correlation was observed between the deep learning parameters of the second diagnostic module and KL-6. Conclusion: Our neural network can differentiate between COVID-19 pneumonia and other pneumonias on CT images, while also distinguishing between ordinary COVID-19 patients and those with white lung. Patients with white lung in COVID-19 have greater alveolar damage compared to ordinary COVID-19 patients, and our deep learning features can serve as an imaging biomarker.

Natural history of indolent-anti-synthetase syndrome-associated interstitial lung disease.

BACKGROUND: Anti-synthetase syndrome-associated interstitial lung disease (ASS-ILD) may occur without myositis. Although a recent Japanese guide proposed a watch-and-wait approach for chronic ASS-ILD without obvious progression, the natural history of this subgroup and the appropriateness of the watch-and-wait approach remain unclear. We aimed to describe the natural history of ASS-ILD, that is sufficiently indolent to be a candidate for the watch-and-wait approach. METHODS: Among consecutive patients with ASS-ILD, we retrospectively identified those without myositis, acute/subacute onset, and significant lung function impairment, which qualified them as indolent-ASS-ILD cases, and described their natural course. Additionally, we evaluated the risk factors for fibrosis progression on computed tomography (CT) using the Cox proportional hazards model. RESULTS: Among 80 patients with ASS-ILD, we identified 33 with indolent-ASS-ILD, all of whom were initially followed up with a watch-and-wait approach. Among 30 patients with sufficient follow-up data, 27 (90%) showed a stable course without treatment over 24 months. Subsequently, four patients experienced ≥10% relative forced vital capacity (FVC) decline without treatment during a median follow-up duration of 81 months. Seven patients showed fibrosis progression with >10% increase in the total lung area on CT. Higher levels of Krebs von den Lungen-6 (KL-6) and surfactant protein-D (SP-D) were associated with fibrosis progression on CT. CONCLUSION: Most patients with indolent-ASS-ILD did not experience ≥10% relative FVC decline over five years without treatment. However, fibrosis progression on CT, which seemed to precede significant FVC decline, occurred more frequently, especially in patients with higher KL-6 and SP-D levels.

Seasonal fluctuation of serum Krebs von den Lungen-6 levels in systemic sclerosis-associated interstitial lung disease.

AIM: To evaluate whether seasonal changes influence fluctuations in serum Krebs von den Lungen-6 (KL-6) levels in systemic sclerosis-related interstitial lung disease (SSc-ILD). METHODS: Summer was defined as the period between July and September, and winter as between December and February. The study was conducted between 2015 and 2016, with a focus on these two seasons. A diagnosis of ILD and ILD progression overtime were evaluated using chest computed tomography. Among patients with SSc-ILD, those with data on serum KL-6 and lactate dehydrogenase (LDH) levels in the 2015 winter, 2015 summer, and 2016 winter seasons were included. Patients with comorbidities that could affect serum KL-6 levels were excluded. RESULTS: Of 60 patients with SSc-ILD, 52 (86.7%) had stable ILD, 5 (8.3%) had worsened ILD, and 3 (5.0%) had improved ILD. Serum KL-6 levels were significantly higher during the winter than those during the summer (2015 winter vs. 2015 summer: 649 U/mL vs. 585 U/mL, p < .0001; 2016 winter vs. 2015 summer: 690 U/mL vs. 585 U/mL, p < .0001). No significant differences were observed between the winters of 2015 and 2016 (649 U/mL vs. 690 U/mL, p = .78). However, serum LDH levels did not exhibit seasonal fluctuations (2015 winter vs. 2015 summer: 203 U/L vs. 199 U/L, p = .3; 2016 winter vs. 2015 summer: 201 U/L vs. 199 U/L, p = .6; 2015 winter vs. 2016 winter: 203 U/L vs. 201 U/L, p = .24). CONCLUSION: Seasonal fluctuations in serum KL-6 levels were observed in patients with SSc-ILD.

Corrigendum: Identifying the link between serum VEGF and KL-6 concentrations: a correlation analysis for idiopathic pulmonary fibrosis interstitial lung disease progression.

[This corrects the article DOI: 10.3389/fmed.2023.1282757.].

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.

Diagnostic Performance of Plasma SP-D, KL-6, and CC16 in Acutely Hospitalised Patients Suspected of Having Community-Acquired Pneumonia-A Diagnostic Accuracy Study.

Community-acquired pneumonia is a common cause of acute hospitalisation. Identifying patients with community-acquired pneumonia among patients suspected of having the disease can be a challenge, which causes unnecessary antibiotic treatment. We investigated whether the circulatory pulmonary injury markers surfactant protein D (SP-D), Krebs von den Lungen-6 (KL-6), and Club cell protein 16 (CC16) could help identify patients with community-acquired pneumonia upon acute admission. In this multi-centre diagnostic accuracy study, SP-D, KL-6, and CC16 were quantified in plasma samples from acutely hospitalised patients with provisional diagnoses of community-acquired pneumonia. The area under the receiver operator characteristics curve (AUC) was calculated for each marker against the following outcomes: patients' final diagnoses regarding community-acquired pneumonia assigned by an expert panel, and pneumonic findings on chest CTs. Plasma samples from 339 patients were analysed. The prevalence of community-acquired pneumonia was 63%. AUCs for each marker against both final diagnoses and chest CT diagnoses ranged between 0.50 and 0.56. Thus, SP-D, KL-6, and CC16 demonstrated poor diagnostic performance for community-acquired pneumonia in acutely hospitalised patients. Our findings indicate that the markers cannot readily assist physicians in confirming or ruling out community-acquired pneumonia.

Safety of Tocilizumab on Rheumatoid Arthritis in Patients with Interstitial Lung Disease.

Purpose: The prognosis of rheumatoid arthritis (RA) with interstitial lung disease (ILD) is particularly poor. Although drugs that do not contribute to the progression of ILD should be used in RA treatment, none have been established. This study evaluated the safety of tocilizumab in terms of ILD activity. Patients and Methods: This study prospectively enrolled all 55 patients with RA complicated by ILD who were treated with tocilizumab at Dokkyo Medical University Saitama Medical Center from April 2014 to June 2022. The outcome measures were MMP-3 and KL-6 as biomarkers of RA and ILD activity, respectively, and the relationship between them was analyzed. Results: Both MMP-3 and KL-6 were significantly improved at 6 months of treatment (P < 0.001 and P < 0.05, respectively), and a weak correlation between MMP-3 and KL-6 was observed (R2 = 0.086, P = 0.087). The group with increased MMP-3 due to RA progression had significantly higher KL-6 at 6 months compared with the group with RA improvement (P < 0.05). Also, the group with ILD progression on computed tomography had significantly higher MMP-3 compared with the groups with improvement or no change of ILD (P < 0.05 and P < 0.01, respectively). The mortality rate was 0% at 6 months, 2.0% at 1 year, 16.7% at 2 years, and 32.4% at 3 years, and mortality from acute exacerbation of ILD due to respiratory infection increased over time. Conclusion: RA activity and ILD activity were found to be related at 6 months of treatment. Tocilizumab does not seem to affect the mechanism of ILD progression, as most patients showed improvement in both MMP-3 and KL-6 with tocilizumab within 6 months, when this drug would be expected to affect the lungs directly. However, respiratory infection exacerbated ILD from 1 year after the start of treatment. As immunosuppressive drugs, including tocilizumab, have a risk of respiratory infection, it is important to identify early signs of infection.

Research progress of KL-6 in respiratory system diseases.

This article comprehensively elucidates the discovery of Krebs von den Lungen-6 (KL-6), its structural features, functional mechanisms, and the current research status in various respiratory system diseases. Discovered in 1985, KL-6 was initially considered a tumor marker, but its elevated levels in interstitial lung disease (ILD) led to its recognition as a relevant serum marker for ILD. KL-6 is primarily produced by type 2 alveolar epithelial cell regeneration. Over the past 30 years since the discovery of KL-6, the number of related research papers has steadily increased annually. Following the coronavirus disease 2019 (COVID-19) pandemic, there has been a sudden surge in relevant literature. Despite KL-6's potential as a biomarker, its value in the diagnosis, treatment, and prognosis varies across different respiratory diseases, including ILD, idiopathic pulmonary fibrosis (IPF), COVID-19, and lung cancer. Therefore, as an important serum biomarker in respiratory system diseases, the value of KL-6 still requires further investigation.

Associations of the Serum KL-6 with Severity and Prognosis in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease.

BACKGROUND: As a biomarker of alveolar-capillary basement membrane injury, Krebs von den Lungen-6 (KL-6) is involved in the occurrence and development of pulmonary diseases. However, the role of the KL-6 in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has yet to be elucidated. This prospective study was designed to clarify the associations of the serum KL-6 with the severity and prognosis in patients with AECOPD. METHODS: This study enrolled 199 eligible AECOPD patients. Demographic data and clinical characteristics were recorded. Follow-up was tracked to evaluate acute exacerbation and death. The serum KL-6 concentration was measured via an enzyme-linked immunosorbent assay. RESULTS: Serum KL-6 level at admission was higher in AECOPD patients than in control subjects. The serum KL-6 concentration gradually elevated with increasing severity of AECOPD. Pearson and Spearman analyses revealed that the serum KL-6 concentration was positively correlated with the severity score, monocyte count and concentrations of C-reactive protein, interleukin-6, uric acid, and lactate dehydrogenase in AECOPD patients during hospitalization. A statistical analysis of long-term follow-up data showed that elevated KL-6 level at admission was associated with longer hospital stays, an increased risk of future frequent acute exacerbations, and increased severity of exacerbation in COPD patients. CONCLUSION: Serum KL-6 level at admission is positively correlated with increased disease severity, prolonged hospital stay and increased risk of future acute exacerbations in COPD patients. There are positive dose-response associations of elevated serum KL-6 with severity and poor prognosis in COPD patients. The serum KL-6 concentration could be a novel diagnostic and prognostic biomarker in AECOPD patients.

Diagnostic Value of Krebs von den Lungen (KL-6) for Interstitial Lung Disease: A European Prospective Cohort.

INTRODUCTION: Krebs von den Lungen 6 (KL-6) is a mucin-1 glycoprotein produced by type II pneumocytes. High levels of KL-6 in blood may be found in patients with lung fibrosis. In Asia this biomarker is used for diagnosis and prognosis in interstitial lung diseases (ILD). There is a lack of information regarding KL-6 cut-off point for diagnosis and prognosis in European population. The aim of this study was to establish the cut-off point for serum KL-6 associated with the presence of ILD in the Spanish population. METHODS: Prospective study including subjects who underwent chest HRCT, PFTs and autoimmune blood analysis. Two groups were created: non-ILD subjects and ILD patients. Serum KL-6 concentrations were measured using a Lumipulse KL-6 reagent assay and the optimal cut-off value was evaluated by a ROC analysis. Data on demographics and smoking history was also collected. RESULTS: One hundred seventy-nine patients were included, 102 with ILD. Median serum KL-6 values overall were 762U/mL, 1080 (±787)U/mL for the ILD group vs 340 (±152)U/mL for the non-ILD group (p<0.0001). The main radiological pattern was NSIP (43%). ROC analysis showed greater specificity (86%) and sensitivity (82%) for KL-6 465U/mL for detecting ILD patients. The multivariate logistic regression model pointed to the male sex, higher KL-6 values, lower FVC and low DLCO values as independent factors associated with ILD. CONCLUSION: Serum KL-6 values greater than 465U/mL have excellent sensitivity and specificity for detecting ILD in our Spanish cohort. Multicentre studies are needed to validate our results.

Use of serum KL-6 and chest radiographic severity grade to predict 28-day mortality in COVID-19 patients with pneumonia: a retrospective cohort study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has had a global social and economic impact. An easy assessment procedure to handily identify the mortality risk of inpatients is urgently needed in clinical practice. Therefore, the aim of this study was to develop a simple nomogram model to categorize patients who might have a poor short-term outcome. METHODS: A retrospective cohort study of 189 COVID-19 patients was performed at Shanghai Ren Ji Hospital from December 12, 2022 to February 28, 2023. Chest radiography and biomarkers, including KL-6 were assessed. Risk factors of 28-day mortality were selected by a Cox regression model. A nomogram was developed based on selected variables by SMOTE strategy. The predictive performance of the derived nomogram was evaluated by calibration curve. RESULTS: In total, 173 patients were enrolled in this study. The 28-day mortality event occurred in 41 inpatients (23.7%). Serum KL-6 and radiological severity grade (RSG) were selected as the final risk factors. A nomogram model was developed based on KL-6 and RSG. The calibration curve suggested that the nomogram model might have potential clinical value. The AUCs for serum KL-6, RSG, and the combined score in the development group and validation group were 0.885 (95% CI: 0.804-0.952), 0.818 (95% CI: 0.711-0.899), 0.868 (95% CI: 0.776-0.942) and 0.932 (95% CI: 0.862-0.997), respectively. CONCLUSIONS: Our results suggested that the nomogram based on KL-6 and RSG might be a potential method for evaluating 28-day mortality in COVID-19 patients. A high combined score might indicate a poor outcome in COVID-19 patients with pneumonia.

Multivariate logistic regression analysis of poor prognosis of dermatomyositis and clinical value of ferritin/Kl-6 in predicting prognosis.

BACKGROUND: Dermatomyositis (DM) is a rare inflammatory disease. Our research focuses on predicting poor prognosis in DM patients and evaluating the prognostic significance of ferritin and Salivary Sugar Chain Antigen-6 (KL-6) through multivariate logistic regression analysis. METHODS: Between February 2018 and April 2020, 80 DM patients at our hospital were categorized into MDA5 positive (n = 20) and negative (n = 60) groups. We conducted multivariate logistic regression to determine DM's poor prognosis risk factors and evaluate ferritin/KL-6's predictive value for prognosis. RESULTS: Analysis showed no gender, age, body mass index (BMI), or lifestyle (smoking, drinking) differences, nor in dyspnea, muscle weakness, skin ulcers, and acetylcysteine treatment effects (p > 0.05). Significant differences emerged in arrhythmias, interstitial pneumonia, C-reactive protein, albumin, and lactate dehydrogenase levels (p < 0.05). Before treatment, differences were negligible (p > 0.05), but post-treatment, serum KL-6 and ferritin levels dropped. MDA5 positive patients had elevated serum KL-6 and ferritin levels than survivors (p < 0.05), with a strong correlation to DM. Combined diagnosis using serum KL-6 and ferritin for DM prognosis showed area under curves of 0.716 and 0.634, significantly outperforming single-index diagnoses with an area under curve (AUC) of 0.926 (p < 0.05). CONCLUSION: Serum KL-6 and ferritin show marked abnormalities in DM, useful as indicators for evaluating polymyositis and DM conditions. However, the study's small sample size is a drawback. Expanding the sample size is essential to monitor serum KL-6 and ferritin changes in DM patients under treatment more closely, aiming to improve clinical assessment and facilitate detailed research.

Krebs von den Lungen-6 levels at admission predicts exercise-induced hypoxemia before and after discharge in patients with COVID-19.

BACKGROUND: There are no reports of exercise-induced hypoxemia in patients with coronavirus disease 2019 (COVID-19). Additionally, the predictive factors and prevalence of exercise-induced hypoxemia are unknown. This study investigated the incidence and predictive factors of exercise-induced hypoxemia before and after discharge in patients with COVID-19. METHODS: We enrolled 77 patients diagnosed with COVID-19 who were hospitalized between November 2020 and October 2021 and who underwent a 6-min walk test before and after discharge. Based on the test results, we classified patients into exercise-induced and non-exercise-induced hypoxemia groups and investigated the predictive factors of exercise-induced hypoxemia using logistic regression analysis. RESULTS: The incidences of exercise-induced hypoxemia in patients with COVID-19 were 37.7% and 19.5% before and after discharge, respectively. At admission, the Krebs von den Lungen-6 levels was the associated factor for exercise-induced hypoxemia in patients with COVID-19 before and after discharge, with cut-off values of 314 U/mL and 367 U/mL, respectively. Age and lactate dehydrogenase levels were the associated factors for exercise-induced hypoxemia in patients with COVID-19 before discharge, with cut-off values of 61 years and 492 U/L, respectively. CONCLUSIONS: Some patients with COVID-19 may continue to experience exercise-induced hypoxemia after discharge. Age, lactate dehydrogenase, and Krebs von den Lungen-6 levels at admission could serve as predictive markers of exercise-induced hypoxemia before and after discharge in these patients.

Two cases of gastric cancer with elevated serum levels of KL-6.

BACKGROUND: The serum level of Krebs von den Lungen-6 (sKL-6) is a biomarker of interstitial pneumonia and has been reported to be elevated in patients with cancers. However, there have been few cases of gastric cancer (GC) with elevated sKL-6 that were treated by chemotherapy. We herein report two cases of GC with elevated sKL-6 that were treated with oxaliplatin plus S-1 (SOX) chemotherapy and discussed the resulting changes in sKL-6. CASE PRESENTATION: The first patient was a 79-year-old woman complaining of loss of appetite. Esophagogastroduodenoscopy (EGD) showed a type-3 tumor in the gastric antrum and biopsy specimens showed adenocarcinoma. Computed tomography (CT) showed multiple liver metastases. sKL-6 was elevated to 1,292 U/ml, but a CT revealed no obvious lesions of the lungs, including interstitial pneumonia. The tumor was diagnosed as GC with liver metastases and elevated sKL-6. Respiratory function data were normal. SOX therapy using oxaliplatin and S-1 was performed. After 3 courses of SOX therapy, CT showed reductions of the liver metastases as well as the primary tumor, and sKL-6 was decreased to 201 U/ml. After the 44 courses, sKL-6 was slightly elevated. Chest CT showed interstitial pneumonia and chemotherapy was stopped. The patient is still alive without any metastasis 72 months later. The second patient was a 69-year-old woman complaining of upper abdominal pain. EGD revealed a type-3 tumor in the gastric antrum showing adenocarcinoma with HER2-positive pathology. CT showed multiple node metastases around the abdominal aorta. sKL-6 was elevated to 2,239 U/ml, but a respiratory function test showed no abnormalities, and CT of the lungs showed no obvious lesions. The tumor was diagnosed as GC with distant node metastases and elevated sKL-6. The patient received SOX therapy combined with trastuzumab. After 6 courses, the size of the primary tumor and multiple node metastases were reduced, and sKL-6 was decreased to 284 U/ml. CONCLUSIONS: These two cases suggest that sKL-6 may be important not only as an indicator of interstitial pneumonia in chemotherapeutic courses, but also as a tumor marker in GC patients with multiple metastases.

Evaluating the diagnostic and therapeutic significance of KL-6 in patients with interstitial lung diseases.

Background: This study aimed to assess the diagnostic value of Krebs von den Lungen-6 (KL-6), Surfactant protein-A (SP-A), SP-D and molecular matrixmetalloproteinase-7 (MMP-7) in discriminating patients with interstitial lung diseases (ILDs) from disease control subjects. Methods: Serum levels of KL-6, SP-A, SP-D and MMP-7 were measured in both the ILD and non-ILD (NILD) groups. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the diagnostic potential of these markers and laboratory indices. High-resolution computed tomography (HRCT) fibrosis scores were determined, and their correlation with the serum markers was analyzed. Results: Serum levels of KL-6 and MMP-7 were significantly elevated in the ILD group compared to the control group, while no significant differences were observed for SP-A and SP-D. ROC analysis of KL-6 demonstrated superior diagnostic accuracy, with a sensitivity of 76.36%, specificity of 91.07%, and an area under curve (AUC) of 0.902 (95%CI 0.866-0.945). These findings were consistent across an additional cohort. Correlation analysis revealed a link between KL-6 levels at initial diagnosis and HRCT fibrosis scores, indicating disease severity. Moreover, a negative correlation was found between KL-6 and pulmonary function indices, reflecting disease progression. Patients with increased 12-month HRCT fibrosis score showed higher lactate dehydrogenase (LDH) levels, with LDH exhibiting an AUC of 0.767 (95% CI: 0.520-0.927) as a predictor of progression. Conclusions: Serum KL-6 detection proves to be a valuable tool for accurately distinguishing ILDs from control subjects. While KL-6 shows a correlation with HRCT fibrosis scores and a negative association with pulmonary function indices, its predictive value for ILDs prognosis is limited. Trial registration: This study received retrospective approval from the Ethical Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (institutional review board ID: TJ-IRB20210331, date: 2021.03.30).

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.