A novel lung injury animal model using KL-6-measurable human MUC1-expressing mice

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.

KL-6 levels in the connective tissue disease population: typical values and potential confounders-a retrospective, real-world study

Background

Krebs von den Lungen 6 (KL-6) is a potential biomarker for determining the severity of interstitial lung disease (ILD) in patients with connective tissue disease (CTD). Whether KL-6 levels can be affected by potential confounders such as underlying CTD patterns, patient-associated demographics, and comorbidities needs further investigation.

Methods

From the database created by Xiangya Hospital, 524 patients with CTD, with or without ILD, were recruited for this retrospective analysis. Recorded data included demographic information, comorbidities, inflammatory biomarkers, autoimmune antibodies, and the KL-6 level at admission. Results of CT and pulmonary function tests were collected one week before or after KL-6 measurements. The percent of predicted diffusing capacity of the lung for carbon monoxide (DLCO%) and computed tomography (CT) scans were used to determine the severity of ILD.

Results

Univariate linear regression analysis showed that BMI, lung cancer, TB, lung infections, underlying CTD type, white blood cell (WBC) counts, neutrophil (Neu) counts, and hemoglobin (Hb) were related to KL-6 levels. Multiple linear regression confirmed that Hb and lung infections could affect KL-6 levels independently; the β were 9.64 and 315.93, and the P values were 0.015 and 0.039, respectively. CTD-ILD patients had higher levels of KL-6 (864.9 vs 463.9, P < 0.001) than those without ILD. KL-6 levels were closely correlated to the severity of ILD assessed both by CT and DLCO%. Additionally, we found that KL-6 level was an independent predictive factor for the presence of ILD and further constructed a decision tree model to rapidly determine the risk of developing ILD among CTD patients.

Conclusion

KL-6 is a potential biomarker for gauging the incidence and severity of ILD in CTD patients. To use this typical value of KL-6, however, doctors should take Hb and the presence of lung infections into account.

Mammalian Neuraminidases in Immune-Mediated Diseases: Mucins and Beyond

Mammalian neuraminidases (NEUs), also known as sialidases, are enzymes that cleave off the terminal neuraminic, or sialic, acid resides from the carbohydrate moieties of glycolipids and glycoproteins. A rapidly growing body of literature indicates that in addition to their metabolic functions, NEUs also regulate the activity of their glycoprotein targets. The simple post-translational modification of NEU protein targets-removal of the highly electronegative sialic acid-affects protein folding, alters protein interactions with their ligands, and exposes or covers proteolytic sites. Through such effects, NEUs regulate the downstream processes in which their glycoprotein targets participate. A major target of desialylation by NEUs are mucins (MUCs), and such post-translational modification contributes to regulation of disease processes. In this review, we focus on the regulatory roles of NEU-modified MUCs as coordinators of disease pathogenesis in fibrotic, inflammatory, infectious, and autoimmune diseases. Special attention is placed on the most abundant and best studied NEU1, and its recently discovered important target, mucin-1 (MUC1). The role of the NEU1 - MUC1 axis in disease pathogenesis is discussed, along with regulatory contributions from other MUCs and other pathophysiologically important NEU targets.

Intratracheal administration of polystyrene microplastics induces pulmonary fibrosis by activating oxidative stress and Wnt/β-catenin signaling pathway in mice

Polystyrene microplastics (PS-MPs) are emerging pollutants that are absorbed by organisms. Due to their small volume and strong biological permeability, they affect the biological functions of cells. In recent years, several studies have detected PS-MPs in air samples, which may damage the human respiratory system following inhalation. The Masson trichrome staining, immunofluorescence, and western blotting assays were conducted to analyze the effects of PS-MPs on pulmonary fibrosis. Alveolar epithelial injuries were assessed through confocal microscopy, and the levels of SOD and GSH were used to evaluate oxidative stress. Our analyzes demonstrated that inhalation of the PS-MPs induces pulmonary fibrosis in a dose-dependent manner in mice. In high dose group (6.25 mg/kg), the PS-MPs significantly increased the expression of α-SMA, Vimentin and Col1a (p < 0.05). Immunofluorescence assays showed decreased levels of SP-C and increased levels of KL-6 in the PS-MPs group. The suppression of SOD (1.46 times) and GSH-Px (2.27 times) indicated that inhalation of microplastics triggered intensive oxidative stress in lungs. Moreover, there was activation of the Wnt/β-catenin signaling pathway in the PS-MPs group. In addition, the data showed that antioxidant melatonin (50 mg/kg) alleviated the PS-MPs-induced pulmonary fibrosis. Taken together, our analysis demonstrated that inhalation of polystyrene microplastics induces pulmonary fibrosis via activation of oxidative stress and Wnt/β-catenin signaling pathway in mice.

Krebs von den Lungen 6 decreased in the serum and muscle of GNE myopathy patients

UDP‐N‐acetylglucosamine 2‐epimerase/N‐acetylmannosamine kinase (GNE) is necessary for sialic acid biosynthesis. GNE myopathy is caused by a defect in GNE, and hyposialylation is a key factor in the pathomechanism of GNE myopathy. Although candidates for evaluating hyposialylation have been reported, it is difficult to measure them in routine clinical practice. Sialylation is necessary for synthesis of various glycoproteins, including Krebs von den Lungen‐6 (KL‐6)/mucin 1 (MUC1). Here we report that KL‐6/MUC1 is decreased in GNE myopathy. We observed that KL‐6 levels were decreased in the serum of patients with GNE myopathy, and that KL‐6 and MUC1‐C were also decreased in muscle biopsy specimens from these patients. An immunofluorescent study revealed that KL‐6 and MUC1‐C were not present in the sarcolemma but were, instead, localized in rimmed vacuoles in specimens from patients with GNE myopathy. KL‐6 is already used to detect lung diseases in clinical practice, and this glycoprotein may be a novel candidate for evaluating hyposialylation in GNE myopathy.

A High-Content Screen for Mucin-1-Reducing Compounds Identifies Fostamatinib as a Candidate for Rapid Repurposing for Acute Lung Injury

Drug repurposing has the advantage of identifying potential treatments on a shortened timescale. In response to the pandemic spread of SARS-CoV-2, we took advantage of a high-content screen of 3,713 compounds at different stages of clinical development to identify FDA-approved compounds that reduce mucin-1 (MUC1) protein abundance. Elevated MUC1 levels predict the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) and correlate with poor clinical outcomes. Our screen identifies fostamatinib (R788), an inhibitor of spleen tyrosine kinase (SYK) approved for the treatment of chronic immune thrombocytopenia, as a repurposing candidate for the treatment of ALI. In vivo, fostamatinib reduces MUC1 abundance in lung epithelial cells in a mouse model of ALI. In vitro, SYK inhibition by the active metabolite R406 promotes MUC1 removal from the cell surface. Our work suggests fostamatinib as a repurposing drug candidate for ALI.

Serum biomarker CA 15-3 as predictor of response to antifibrotic treatment and survival in idiopathic pulmonary fibrosis

Aim: Cancer antigen 15-3 (CA 15-3) is a baseline biomarker in idiopathic pulmonary fibrosis (IPF), but its value during follow-up is unknown. Materials and methods: Associations between serum CA 15-3 and pulmonary function tests during 1-year follow-up were evaluated by a mixed model in 132 IPF treated with pirfenidone or nintedanib. Results: Increased baseline (median: 56 kU/l) and follow-up CA 15-3 levels were inversely associated with forced vital capacity and diffusing capacity of the lung for carbon monoxide (estimates respectively: -5.21 and -4.69; p < 0.001). Baseline and 6-month CA 15-3 above 58.5 (hazard ratio: 1.67; p = 0.031) and 50.5 kU/l (hazard ratio: 2.99; p < 0.001), respectively, showed impaired survival compared with lower levels. Conclusion: CA 15-3 is associated with pulmonary function test during follow-up in IPF on antifibrotic treatment. Higher (follow-up) values are related with poor survival. Therefore, CA 15-3 is a promising follow-up biomarker in IPF.

A High Content Screen for Mucin-1-Reducing Compounds Identifies Fostamatinib as a Candidate for Rapid Repurposing for Acute Lung Injury during the COVID-19 pandemic

Drug repurposing is the only method capable of delivering treatments on the shortened time-scale required for patients afflicted with lung disease arising from SARS-CoV-2 infection. Mucin-1 (MUC1), a membrane-bound molecule expressed on the apical surfaces of most mucosal epithelial cells, is a biochemical marker whose elevated levels predict the development of acute lung injury (ALI) and respiratory distress syndrome (ARDS), and correlate with poor clinical outcomes. In response to the pandemic spread of SARS-CoV-2, we took advantage of a high content screen of 3,713 compounds at different stages of clinical development to identify FDA-approved compounds that reduce MUC1 protein abundance. Our screen identified Fostamatinib (R788), an inhibitor of spleen tyrosine kinase (SYK) approved for the treatment of chronic immune thrombocytopenia, as a repurposing candidate for the treatment of ALI. In vivo , Fostamatinib reduced MUC1 abundance in lung epithelial cells in a mouse model of ALI. In vitro , SYK inhibition by Fostamatinib promoted MUC1 removal from the cell surface. Our work reveals Fostamatinib as a repurposing drug candidate for ALI and provides the rationale for rapidly standing up clinical trials to test Fostamatinib efficacy in patients with COVID-19 lung injury.

Clinical Significance of Serum Chitotriosidase Level in Anti-MDA5 Antibody–positive Dermatomyositis-associated Interstitial Lung Disease

Objective.

To assess prognostic factors of antimelanoma differentiation-associated gene 5 antibody (anti-MDA5)–positive dermatomyositis/clinically amyopathic DM–associated interstitial lung disease (DM/CADM-ILD) and evaluate the use of serum chitotriosidase, a marker for macrophage activation, as a potential biomarker in anti-MDA5-positive DM/CADM-ILD.

Methods.

This retrospective study included 30 patients with anti-MDA5–positive DM/CADM-ILD. The clinical characteristics and laboratory findings at the time of diagnosis were analyzed. Serum chitotriosidase levels were measured in the 30 patients, in 21 healthy controls, and in 25 patients with anti-aminoacyl-tRNA synthetase antibody–positive (anti-ARS)-polymyositis (PM)/DM/CADM-ILD, and the potential of serum chitotriosidase as a prognostic biomarker in anti-MDA5–positive DM/CADM-ILD was assessed.

Results.

The median serum chitotriosidase level in patients with anti-MDA5–positive DM/CADM-ILD was 17.3 ng/ml, which was higher than that in healthy controls and anti-ARS–PM/DM/CADM-ILD (2.0 and 8.9 ng/ml, respectively). Of the 30 patients, 10 died of respiratory failure associated with DM/CADM-ILD deterioration. Cox hazard analysis demonstrated that higher serum chitotriosidase level and lower PaO2 value were significant predictors of a poor outcome. Using optimal cutoff levels according to receiver-operating characteristic curve analyses, chitotriosidase ≥ 23.5 ng/ml, ferritin ≥ 800 ng/ml, and Krebs von den Lungen–6 ≥ 720 U/ml were significantly associated with a poor prognosis. Serum chitotriosidase levels were negatively correlated with PaO2 and percentage predicted forced vital capacity. The survival rate was significantly poorer in patients with high chitotriosidase levels (≥ 23.5 ng/ml) than in those with low chitotriosidase levels (< 23.5 ng/ml).

Conclusion.

Serum chitotriosidase may be a potential biomarker for predicting a poor prognosis in patients with anti-MDA5–positive DM/CADM-ILD.

Dissociation between systemic and pulmonary anti-inflammatory effects of dexamethasone in humans

Aims

The local pulmonary inflammatory response has a different temporal and qualitative profile compared with the systemic inflammatory response. Although glucocorticoids substantially downregulate the systemic release of acute‐phase mediators, it is not clear whether they have comparable inhibitory effects in the human lung compartment. Therefore, we compared the anti‐inflammatory effects of a pure glucocorticoid agonist, dexamethasone, on bronchoalveolar lavage and blood cytokine concentrations in response to bronchially instilled endotoxin.

Methods

In this randomized, double‐blind and placebo‐controlled trial, 24 volunteers received dexamethasone or placebo and had endotoxin instilled into a lung segment and saline instilled into a contralateral segment, followed by bronchoalveolar lavage.

Results

Bronchially instilled endotoxin induced a local and systemic inflammatory response. Dexamethasone strongly blunted the systemic interleukin (IL) 6 and C‐reactive protein release. In sharp contrast, dexamethasone left the local release of acute‐phase mediators in the lungs virtually unchanged: bronchoalveolar lavage levels of IL‐6 were only 18% lower and levels of IL‐8 were even higher with dexamethasone compared with placebo, although the differences between treatments were not statistically significant (P = 0.07 and P = 0.08, respectively). However, dexamethasone had inhibitory effects on pulmonary protein extravasation and neutrophil migration.

Conclusions

The present study demonstrated a remarkable dissociation between the systemic anti‐inflammatory effects of glucocorticoids and its protective effects on capillary leak on the one hand and surprisingly low anti‐inflammatory effects in the lungs on the other.

Changes in pulmonary tissue structure and KL-6/MUC1 expression in a newborn rat model of hyperoxia-induced bronchopulmonary dysplasia

Following preterm birth, levels of Krebs von den Lungen-6/mucin 1 (KL-6/MUC1) in serum correlate closely with the development of advanced bronchopulmonary dysplasia (BPD), but the role of KL-6/MUC1 in the development of BPD is unclear. To explore whether a relationship exists between KL-6/MUC1 and pathological changes in BPD and verify such a clinical finding, we established a newborn rat model of 95% oxygen-induced BPD. The development of pulmonary alveoli was evaluated by determining the radial alveolar count (RAC) and examining the location, distribution, and expression of KL-6/MUC1 in pulmonary tissues using a fluorescent immunoassay, Western blot, and reverse transcription polymerase chain reaction. The synchronic expression levels of KL-6/MUC1 in serum, bronchoalveolar lavage fluid (BALF) and pulmonary tissues were examined using an enzyme-linked immunosorbent assay. The mean RAC in the hyperoxia group was significantly lower than in normoxia controls, whereas the expression levels of KL-6/MUC1 were higher. On days 1, 3, 7, and 14, the mean RACs in hyperoxic rats were 15.00, 12.67, 12.00, and 11.33, respectively. The expression levels of KL-6/MUC1 peaked in the experimental group on day 1, and began to decrease slightly after day 3. The expression levels of KL-6/MUC1 in serum and BALF were associated with KL-6/MUC1 expression in pulmonary tissues. We suggest that increased lung KL-6/MUC1 expression appears to be closely associated with impairment of alveolarization in a newborn rat model of hyperoxia-induced BPD. Changes in lung KL-6/MUC1 expression can be evaluated effectively and less invasively by monitoring KL-6/MUC1 in serum and BALF.