CA 15 - 3 in screening for systemic autoimmune rheumatic disease associated interstitial lung disease: a single center cross-sectional study.

INTRODUCTION: The natural course of interstitial lung disease (ILD) in patients with systemic autoimmune rheumatic diseases (SARD) varies significantly and is linked to considerable morbidity and mortality. Therefore, effective screening is crucial for early detection of SARD-ILD. Biomarkers associated with mucin 1, Krebs von den Lungen-6 (KL-6) and carbohydrate antigen 15-3 (CA 15-3), are increased in various ILD. This study aimed to assess the diagnostic accuracy of the serum biomarker CA 15-3 as a potential screening tool for ILD in patients newly diagnosed with SARD. METHODS: Conducted as a single-center cross-sectional study, the research included newly diagnosed SARD patients consecutively examined for ILD according to the algorithm. All included patients underwent chest high-resolution CT scans (HRCT), and serum levels of CA 15-3, KL-6, and lactate dehydrogenase (LDH) were measured and correlated with other variables associated with possible ILD presence. RESULTS: Serum biomarker levels, specifically CA 15-3 and LDH, are significantly higher in ILD-positive patients (P<0.001 for both). An inverse relationship is observed between higher FVC values and lower CA 15-3 levels (Rho=-0.291, P=0.007). Similarly, higher DLCO values are associated with lower CA 15-3 levels (Rho=-0.317, P=0.003). Our findings revealed that elevated CA 15-3 levels are positively correlated with higher levels of KL-6 (Rho=0.268, P=0.01) and LDH (Rho=0.227, P=0.04). With a cut-off value of 24 U/mL, CA 15-3 showed the highest sensitivity and specificity (AUC=0.807, specificity=95.7%, sensitivity=71.1%). CA 15-3 emerged as the most significant predictor of a positive HRCT finding, accurately classifying 83% of cases. CONCLUSION: These results suggest that CA 15-3 shows promise as a valuable serum biomarker for screening SARD patients for ILD in routine clinical practice.

[Evaluation of Serum KL-6 Levels in Metastatic Gastric Cancer Patients without Interstitial Lung Disease].

Serum KL-6 is elevated in patients with various diseases such as interstitial lung disease(ILD), lung cancer, or breast cancer. However, whether serum KL-6 levels would be increased in patients with gastric cancer remains unclear. In this study, we aimed to reveal the frequency and characteristics of patients with gastric cancer exhibiting high serum KL-6 levels and no ILD. Therefore, we retrospectively reviewed the medical records of patients with gastric cancer and serum KL-6 levels measured prior to nivolumab-containing therapies. No patients had ILD at pretreatment. The median serum KL-6 level at pretreatment was 314 U/mL. Serum KL-6 levels increased above 500 U/mL in 16 of 56 patients at pretreatment. Serum KL-6 levels were higher in smokers and ex-smokers than in never-smokers as well as in patients with multiple metastases than in those with a single metastatic lesion. Moreover, we conducted a representative case presentation. Due to the increasing immune checkpoint inhibitor use in gastric cancer management, awareness concerning potentially increased serum KL-6 levels in patients with gastric cancer without ILD would be useful for physicians due to the more frequent opportunities to measure serum KL-6 levels for early detection and differential diagnosis of ILD.

Prognostic performance of Krebs von den Lungen-6, surfactant protein A, surfactant protein D levels in the serum and bronchoalveolar lavage fluid in chronic fibrosing interstitial pneumonia: a retrospective study.

BACKGROUND: The serum markers Krebs von den Lungen-6 (KL-6), surfactant protein A (SP-A), and surfactant protein D (SP-D) have been used for the diagnosis, differential diagnosis, and prognosis prediction of interstitial pneumonia. However, the significance of measuring the serum and bronchoalveolar lavage fluid (BALF) KL-6, SP-D, and SP-A levels in predicting the prognosis of chronic fibrosing interstitial pneumonia (CFIP), idiopathic pulmonary fibrosis, and idiopathic nonspecific interstitial pneumonia remains unclear. We aimed to clarify the significance of measuring the serum and BALF KL-6, SP-A, and SP-D levels in predicting the prognosis of patients with CFIP. METHODS: Among 173 patients who were diagnosed with CFIP between September 2008 and February 2021, 39 who underwent bronchoalveolar lavage were included in this study. Among these, patients experiencing an annual decrease in forced vital capacity (FVC) of ≥10% or those facing challenges in undergoing follow-up pulmonary function tests owing to significant deterioration in pulmonary function were categorized as the rapidly progress group. Conversely, individuals with an annual decrease in the FVC of <10% were classified into the slowly progress group. The serum and BALF KL-6, SP-D, and SP-A levels, as well as BALF/serum SP-D and SP-A ratios were compared between the two groups. RESULTS: Among the patients with CFIP, the BALF SP-D level (p=0.0111), BALF SP-A level (p<0.0010), BALF/serum SP-D ratio (p=0.0051), and BALF/serum SP-A ratio (p<0.0010) were significantly lower in the rapidly than in the slowly progress group (p<0.0010). The receiver operating characteristics analysis results demonstrated excellent performance for diagnosing patients with CFIP, with the BALF SP-D level (area under the curve [AUC], 0.7424), BALF SP-A level (AUC, 0.8842), BALF/serum SP-D ratio (AUC, 0.7673), and BALF/serum SP-A ratio (AUC, 0.8556). Moreover, the BALF SP-A level showed a notably superior CFIP diagnostic capability. Survival analysis using the Kaplan-Meier method revealed that patients with a BALF SP-A level of <1500 ng/mL and BALF/serum SP-A ratio of <15.0 had poor prognoses. CONCLUSIONS: Our results suggest that BALF SP-A measurement may be useful for predicting the prognosis in patients with CFIP.

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.

The clinical value of KL-6 for predicting the occurrence and severity of connective tissue disease-associated interstitial lung disease is not affected by CTD type or treatment.

Objective: The aim of this study was to explore the potential values of Krebs von den Lungen-6 (KL-6), neutrophil to lymphocyte ratio (NLR), systemic immune inflammation (SII), platelet to lymphocyte ratio (PLR), monocyte to lymphocyte ratio (MLR) and red blood cell distribution width (RDW) in the diagnosis and evaluation of the severity of connective tissue disease-associated interstitial lung disease (CTD-ILD). Methods: A total of 140 connective tissue disease (CTD) patients and 85 CTD-ILD patients were recruited for this study at Shanxi Provincial People's Hospital from May 2022 to May 2023. Patients were divided into subgroups based on medication history and CTD subtypes to compare and analyze the clinical data and laboratory parameters of CTD-ILD patients and CTD patients. The receiver operating characteristic curve (ROC) was used to evaluate the diagnostic efficacy of KL-6, NLR, SII, PLR, MLR, and RDW in identifying CTD-ILD patients from CTD patients. A Spearman correlation analysis was conducted to elucidate the correlations between these markers and the lung function parameters of forced vital capacity (FVC, %), forced expired volume in one second (FEV1, %), and diffusing capacity of carbon monoxide (DLCO, %). Finally, binary logistic regression analysis was applied to discern the independent risk factors for CTD-ILD. Results: NLR, SII, MLR, RDW, and KL-6 displayed significant statistical differences in the experimental groups. In both untreated and treated subgroups, KL-6 displayed higher values for CTD-ILD than CTD among all CTD subtypes. In untreated subgroups, there were significant differences in MLR levels between rheumatoid arthritis (RA) and RA-ILD patients and in NLR levels between Sjögren syndrome (SjS) and SjS-ILD patients. There were also significant differences in RDW-SD between the "other CTD" and "other CTD-ILD" groups. In treated subgroups, there were significant differences in both RDW-SD and RDW-CV between RA and RA-ILD patients and in NLR, SII, MLR, PLR, and RDW-SD between "other CTD" and "other CTD-ILD" groups. ROC revealed that KL-6 emerged as the most effective predictor for CTD-ILD in both treated and untreated groups. The multivariate logistic regression analysis results showed that both KL-6 and age were independent risk factors for CTD-ILD. NLR, SII, and PLR were negatively correlated with DLCO (%) in the untreated CTD-ILD group, and KL-6 was negatively correlated with various lung function parameters in both treated and untreated CTD-ILD groups. Conclusion: KL-6 emerged as the most promising biomarker for diagnosing CTD-ILD and assessing its severity. The diagnostic value of KL-6 was unaffected by medication interference and surpassed the value of other parameters, such as NLR, SII, MLR, and RDW. The diagnostic value of RDW-SD was higher than that of RDW-CV in CTD-ILD patients. NLR, SII, MLR, and PLR have potential value in diagnosing the different types of CTD-ILD.

Krebs von den Lungen-6 as biomarker of the new progressive fibrotic phenotype of interstitial lung disease.

BACKGROUND: Novel progressive fibrotic phenotype has recently been proposed characterized by progressive and inexorable worsening of the disease. Krebs von den Lungen-6 (KL-6) has been proposed as fibrotic-ILD biomarker. We aimed to assess the role of KL-6 in fibrotic-ILD and the progressive phenotype in accordance with serial serum KL-6. METHODS: 107 patients were enrolled in the study (median age,IQR, 65(54-71)y/o) followed at respiratory diseases and rheumatology units of University of Siena. Thirty-five had diagnoses of IPF, 18 sarcoidosis, 10 PLCH, 5 LAM, 24 fibrotic HP(fHP), 13 RA (4/13 RA-ILD) and 22 SSc (18/22 SSc-ILD). Serial serum samples were collected before therapy (t0) and 24 months later (t1) from IPF, SSc- and RA-ILD patients. Twenty-two healthy controls (HC) were enrolled. Serum samples were assayed for KL-6 concentrations (Fujirebio Europe, Gent, Belgium). RESULTS: Higher KL-6 concentrations were reported in IPF, fHP and SSc-ILD patients than HC (p<0.0001). KL-6 cut-off value of 885 U/mL identified fibrotic-ILD patients. Logistic regression analysis indicated KL-6 (p=0.004) and smoking-habit (p=0.005) affected the ILD diagnosis. The decision tree model showed KL-6>1145 U/mL, DLco≤60.15 %, FVC≤86 % to classify 86 % IPF patients. Inverse correlation between T0-KL-6 and T1-FVC%(r=-0.314, p=0.046) and T1-DLco%(r=-0.327, p=0.038) in the progressive group. CONCLUSION: KL-6 proved to be a reliable marker for diagnosis and prognosis of fibrotic ILD patients with predictive value in progressive fibrotic patients and a useful marker to identify the new and similar progressive phenotype of IPF and SSc-ILD patients assessing the functional progression in accordance with serial serum KL-6 measurements.

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.

Biomarkers of tissue remodelling are elevated in serum of COVID-19 patients who develop interstitial lung disease - an exploratory biomarker study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is a viral pneumonia that can result in serious respiratory illness. It is associated with extensive systemic inflammation, changes to the lung extracellular matrix, and long-term lung impairment such as interstitial lung disease (ILD). In this study, the aim was to investigate whether tissue remodelling, wound healing, and neutrophil activity is altered in patients with COVID-19 and how these relate to the development of post-COVID ILD. METHOD: Serum samples were collected from 63 patients three months after discharge as part of the Research Evaluation Alongside Clinical Treatment study in COVID-19 (REACT COVID-19), 10 of whom developed ILD, and 16 healthy controls. Samples were quantified using neo-epitope specific biomarkers reflecting tissue stiffness and formation (PC3X, PRO-C3, and PRO-C6), tissue degradation (C1M, C3M, and C6M), wound healing (PRO-FIB and X-FIB), and neutrophil activity (CPa9-HNE and ELP-3). RESULTS: Mean serum levels of PC3X (p < 0.0001), PRO-C3 (p = 0.002), C3M (p = 0.009), PRO-FIB (p < 0.0001), CPa9-HNE (p < 0.0001), and ELP-3 (p < 0.0001) were significantly elevated in patients with COVID-19 compared to healthy controls. Moreover, PC3X (p = 0.023) and PRO-C3 (p = 0.032) were significantly elevated in post-COVID ILD as compared to COVID-19. CONCLUSION: Serological biomarkers reflecting type III collagen remodelling, clot formation, and neutrophil activity were significantly elevated in COVID-19 and type III collagen formation markers were further elevated in post-COVID ILD. The findings suggest an increased type III collagen remodelling in COVID-19 and warrants further investigations to assess the potential of tissue remodelling biomarkers as a tool to identify COVID-19 patients at high risk of developing ILD.

Rapid Progression of Acute Interstitial Pneumonia in a Patient with Low MDA-5 Antibody Titer.

BACKGROUND Melanoma differentiation associated gene-5 antibody (MDA-5 Ab) is one of the diagnostic autoantibodies that appears in idiopathic inflammatory myopathies (IIMs). Unlike when other autoantibodies are positive, when this antibody is positive, there is less characteristic muscle involvement. However, this MDA-5 Ab-positive myopathy presents extremely rapid progression of interstitial lung disease, resulting in a high mortality rate. Previous studies reported that the prognosis of this lung disease will be determined by the titer and suggest that low titers of MDA-5 antibody can indicate a good prognosis in associated interstitial lung disease. CASE REPORT Our case describes a 55-year-old woman who presented with acute respiratory symptoms and dyspnea. After hospitalization, symptoms and chest imaging worsened rapidly, and the radiology image of lung disease featured interstitial changes not seen in typical infections. We treated the patient with a high-flow oxygen nasal cannula, empirical antibiotics, and a systemic steroid. While treatment for a disease of unknown cause was continued, low titer of MDA-5 antibody was identified. CONCLUSIONS This case suggests 2 points to consider about non-infectious interstitial changes with acute respiratory distress syndrome. First, when treating rapidly progressing interstitial pneumonia of an unknown cause, it is recommended to consider lung involvement of MDA-5 Ab dermatomyositis. Second, a low titer of MDA-5 Ab can be associated with better prognosis in this MDA-5 Ab dermatomyositis-related lung disease.

Persistence of lung structural and functional alterations at one year post-COVID-19 is associated with increased serum PD-L2 levels and altered CD4/CD8 ratio.

BACKGROUND: Persistent respiratory symptoms and lung abnormalities post-COVID-19 are public health problems. This study evaluated biomarkers to stratify high-risk patients to the development or persistence of post-COVID-19 interstitial lung disease. METHODS: One hundred eighteen patients discharged with residual lung abnormalities compatible with interstitial lung disease (COVID-ILD patients) after a severe COVID-19 were followed for 1 year (post-COVID-ILD patients). Physical examination, pulmonary function tests, and chest high-resolution computed tomography (HRCT) were performed. Soluble forms (s) of PD-L1, PD-L2, TIM-3, and GAL-9 were evaluated in serum and cell culture supernatant, as well as T-cells subsets and the transmembrane expression of PD-L1 and PD-L2 on the cell surface. RESULTS: Eighty percent of the post-COVID-ILD patients normalized their lung function at 1-year follow-up, 8% presented COVID-independent ILD, and 12% still showed functional and HRCT alterations. PD-L2 levels were heterogeneous during acute COVID-19 (aCOVID); patients who increased (at least 30%) their sPD-L2 levels at 1 year post-COVID-19 and exhibited altered CD4/CD8 ratio showed persistence of chest tomographic and functional alterations. By contrast, patients who decreased sPD-L2 displayed a complete lung recovery. sPD-L1, sTIM-3, and sGAL-9 increased significantly during aCOVID and decreased in all patients after 1-year follow-up. CONCLUSION: Increased sPD-L2 and an altered CD4/CD8 ratio after 12 months of aCOVID are associated with the persistence of lung lesions, suggesting that they may contribute to lung damage post-COVID-19.

Serum stratifin measurement is useful for evaluating disease severity and outcomes in patients with acute exacerbation of interstitial lung disease: a retrospective study.

BACKGROUND: Serum levels of stratifin (SFN), a member of the 14-3-3 protein family, increase in patients with drug-induced lung injury associated with diffuse alveolar damage. Therefore, we hypothesised that SFN levels would be higher in those experiencing acute exacerbation of interstitial lung disease (AE-ILD). A secondary analysis was also planned to determine whether SFN levels could discriminate survival in those with AE. METHODS: Thirty-two patients with clinically stable ILD (CS-ILD) and 22 patients with AE-ILD were examined to assess whether high serum SFN levels were associated with AE-ILD and whether SFN levels reflected disease severity or prognosis in patients with AE-ILD. RESULTS: Serum SFN levels were higher in the AE-ILD group than in the CS-ILD group (8.4 ± 7.6 vs. 1.3 ± 1.2 ng/mL, p < 0.001). The cut-off value of the serum SFN concentration for predicting 90-day and 1-year survival was 6.6 ng/mL. SFN levels were higher in patients who died within 90 days and 1 year than in patients who survived beyond these time points (13.5 ± 8.7 vs. 5.6 ± 5.3 ng/mL; p = 0.011 and 13.1 ± 7.5 vs. 3.1 ± 1.9 ng/mL; p < 0.001, respectively) in the AE-ILD group. When this cut-off value was used, the 90-day and 1-year survival rates were significantly better in the population below the cut-off value than in those above the cut-off value (p = 0.0017 vs. p < 0.0001). CONCLUSIONS: High serum SFN levels are associated with AE-ILD and can discriminate survival in patients with AE-ILD.

Elevated peripheral blood monocyte count is associated with prolonged postoperative hospitalization and functional decline in patients with interstitial lung diseases undergoing surgical lung biopsy.

OBJECTIVE: Monocyte count and red cell distribution width (RDW) have shown prognostic potential in patients with fibrotic lung diseases. Their kinetics and prognostic usefulness of peripheral blood indices in patients with interstitial lung diseases (ILDs) undergoing surgical lung biopsy for diagnostic reasons have not been studied. PATIENTS AND METHODS: We retrospectively included consecutive patients with ILD who underwent surgical lung biopsy for diagnostic purposes Between 07/11/2019 and 11/10/2022. RESULTS: Fifty-five (n=55) patients were included in the study. Median age was 65.0 years (95% CI: 63.0 to 66.0). Postoperative peripheral blood monocyte count on Day 1 was significantly higher compared to preoperative, perioperative, and postoperative values on Day 90 (repeated measures ANOVA, p<0.0001). Patients in the high postoperative monocyte count group had significantly increased length of postoperative hospital stay [Mann-Whitney test, p=0.007] and significantly lower Forced Vital Capacity (FVC)% predicted 3 months after surgery [Mann-Whitney test, p=0.029] compared to patients in the low postoperative monocyte count group. Postoperative RDW on Day 90 was significantly higher compared to preoperative, perioperative and postoperative-Day 1 RDW (repeated measures ANOVA, p=0.008, p=0.006, p<0.0001, respectively). Patients in the high postoperative RDW group did not have increased hospital stay (Mann-Whitney test, p=0.49) or decreased FVC% predicted at 3 months compared to patients in the low postoperative RDW group (Mann-Whitney test, p=0.91). CONCLUSIONS: Peripheral blood monocyte count could be a prognostic biomarker for patients with ILDs undergoing diagnostic surgical lung biopsies. RDW does not seem to represent an acute phase biomarker but seems to increase over time following disease progression. Larger studies are urgently required.

Serum S1P level in interstitial lung disease (ILD) is a potential biomarker reflecting the severity of pulmonary function.

BACKGROUND: sphingosine-1-phosphate (S1P), a naturally occurring sphingolipid, has been involved in pulmonary interstitial remodeling signaling. However, no study has examined its clinical merits for interstitial lung disease (ILD). This study aimed to investigate the serum level of S1P in ILD patients and its clinical correlation with the severity of disease in the two main types of ILDs: the IPF and the CTD-ILD patients. METHODS: This retrospective observational pilot study included 67 ILD patients and 26 healthy controls. These patients were stratified into the IPF group (35) and the CTD-ILD group (32). The severity of ILD was evaluated through pulmonary function indicators and the length of hospital stay. RESULTS: Serum S1P level was statistically higher in ILD patients than in health control (p = 0.002), while the Serum S1P levels in CTD-ILD and IPF patients were comparable. Serum S1P level further showed statistically negative correlation with pulmonary function indexes (TLC% pred, FVC% pred and FEV1% pred) and positive correlation with length of hospital stay (r = -0.38, p = 0.04; r = -0.41, p = 0.02, r = -0.37, p = 0.04; r = 0.42, p = 0.02, respectively) in CTD-ILD patients, although serum S1P level was not significantly correlated with inflammatory indexes. The IPF patients failed to exhibit a significant correlation of serum S1P level with pulmonary function and length of hospital stay. CONCLUSIONS: Serum S1P level might be a clinically useful biomarker in evaluating the severity of CTD-ILD patients rather than IPF patients.

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.

Soluble CXCL16 is a prognostic biomarker associated with rapidly progressive interstitial lung disease complicated with dermatomyositis.

OBJECTIVES: Rapidly progressive interstitial lung disease (RPILD) in patients with dermatomyositis (DM) significantly impacts prognosis, leading to high mortality rates. Although several indicators have been demonstrated to strongly correlate with the risk of developing RPILD, their clinical utility still needs to be investigated. The objective of this study was to investigate the clinical significance of soluble CXCL16 (sCXCL16) in DM patients complicated with RPILD. METHODS: Serum sCXCL16 was measured by enzyme-linked immunosorbent assay in 96 patients with DM and 55 matching healthy donors. Correlations between sCXCL16 levels and clinical features, laboratory examinations and the predictive value of baseline sCXCL16 level for RPILD were analysed. RESULTS: The serum sCXCL16 levels were significantly higher in patients with DM (n = 96, 3.264 ± 1.516 ng/mL) compared with healthy donors (n = 55, 1.781 ± 0.318 ng/mL), especially in DM complicated with RPILD (n = 31, 4.441 ± 1.706 ng/mL). The sCXCL16 levels were positively correlated with levels of serum ferritin, C reactive protein, erythrocyte sedimentation rate, lactate dehydrogenase, hydroxybutyrate dehydrogenase, and negatively correlated with peripheral lymphocytes percentage, but showed no correlation with levels of anti-melanoma differentiation-associated gene 5 antibody, Krebs von den Lungen-6 or creatine kinase. Multivariable analysis showed that elevated sCXCL16 was an independent prognostic factor for poor prognosis of RPILD in patients with DM. The 2-year survival rate was significantly lower in patients with high sCXCL16 level than in those with low sCXCL16 level. CONCLUSION: A higher serum sCXCL16 level was identified as a predictive biomarker of RPILD in patients with DM, and closely associated with poor prognosis.

Peripheral Th17/Treg imbalance in Chinese patients with untreated antisynthetase syndrome associated interstitial lung disease.

Interstitial lung disease (ILD) is a common and fatal manifestation of antisynthetase syndrome (ASS). The aim of this study was to provide new insight into investigate peripheral blood lymphocytes, CD4+ T cells, cytokine levels and their relation to the clinical profile of untreated patients with ASS-ILD. The retrospective study population included thirty patients diagnosed with ASS-ILD and 30 healthy controls (HCs). Baseline clinical and laboratory data were collected for all subjects, including peripheral blood lymphocyte, CD4+ T cell subsets measured by flow cytometry, and serum cytokine levels measured by multiple microsphere flow immunofluorescence. Their correlations with clinical and laboratory findings were analyzed by Pearson's or Spearman's correlation analysis. In addition, the Benjamini-Hochberg method was used for multiple correction to adjust the p-values. Patients with ASS-ILD had lower CD8+ T cells, higher proportion of Th17 cells and Th17/Treg ratio than HCs. Serum cytokine levels (IL-1ß, IL-6, IL-12, IL-17, IL-8, IL-2, IL-4, IL-10, TNF-α and IFN-γ) were higher in patients with ASS-ILD than HCs. Moreover, Th17/Treg ratio was negatively correlated with diffusing capacity of carbon monoxide (DLCO)%. Our study demonstrated abnormalities of immune disturbances in patients with ASS-ILD, characterized by decreased CD8+ T cells and an increased Th17/Treg ratio, due to an increase in the Th17 cells. These abnormalities may be the immunological mechanism underlying the development of ILD in ASS.

SFTPB in serum extracellular vesicles as a biomarker of progressive pulmonary fibrosis.

Progressive pulmonary fibrosis (PPF), defined as the worsening of various interstitial lung diseases (ILDs), currently lacks useful biomarkers. To identify novel biomarkers for early detection of patients at risk of PPF, we performed a proteomic analysis of serum extracellular vesicles (EVs). Notably, the identified candidate biomarkers were enriched for lung-derived proteins participating in fibrosis-related pathways. Among them, pulmonary surfactant-associated protein B (SFTPB) in serum EVs could predict ILD progression better than the known biomarkers, serum KL-6 and SP-D, and it was identified as an independent prognostic factor from ILD-gender-age-physiology index. Subsequently, the utility of SFTPB for predicting ILD progression was evaluated further in 2 cohorts using serum EVs and serum, respectively, suggesting that SFTPB in serum EVs but not in serum was helpful. Among SFTPB forms, pro-SFTPB levels were increased in both serum EVs and lungs of patients with PPF compared with those of the control. Consistently, in a mouse model, the levels of pro-SFTPB, primarily originating from alveolar epithelial type 2 cells, were increased similarly in serum EVs and lungs, reflecting pro-fibrotic changes in the lungs, as supported by single-cell RNA sequencing. SFTPB, especially its pro-form, in serum EVs could serve as a biomarker for predicting ILD progression.

Serum KL-6 and the mortality of patients with connective tissue disease-associated interstitial lung disease: A meta-analysis.

Connective tissue disease-associated interstitial lung disease (CTD-ILD) is an important underlying cause of morbidity and mortality in patients with CTD. Serum Krebs von den Lungen-6 (KL-6) is an immune factor which has been related to the severity of ILD. This systematic review and meta-analysis aimed to evaluate the association between serum KL-6 and mortality of patients with CTD-ILD. Longitudinal studies relevant to the aim of the meta-analysis were retrieved by search of electronic databases including PubMed, Web of Science, and Embase. A random-effects model was used to combine the data by incorporating the influence of between-study heterogeneity. Fifteen cohorts involving 1737 patients with CTD-ILD were included. During a mean follow-up of 35.3 months, 430 (24.8%) patients died. Compared to those with a lower KL-6 at admission, patients with a higher KL-6 were associated with a higher mortality risk during follow-up (risk ratio: 2.18, 95% confidence interval: 1.66 to 2.87, P < 0.001; I2 = 20%). Subgroup analysis showed a significant association in studies from Asian countries, but not in those from non-Asian countries; in studies with cutoff of KL-6 derived in receiver operating characteristic (ROC) curve analysis, but not in those derived from other methods; in studies with multivariate analysis, but not in those with univariate analysis (P for subgroup difference all < 0.05). The association was not significantly affected by different CTDs or methods for measuring serum KL-6. In conclusion, a high serum KL-6 may be a risk factor of increased mortality in patients with CTD-ILD.