Increased KL-6 levels in moderate to severe COVID-19 infection

Increased circulating levels of SP-D and IL-10 are associated with the development of disease severity and pulmonary fibrosis in patients with COVID-19

Background

Patients with severe COVID-19 can rapidly develop acute respiratory distress syndrome (ARDS), which further increases the risk of developing pulmonary fibrosis. The exact role of macrophage polarization and different cytokine production in the pathophysiology associated with COVID-19 induced ARDS or pulmonary fibrosis is unknown. It is necessary to identify potential biomarkers that can predict the progress of pulmonary fibrosis or other adverse consequences.

Methods

We analyze the plasma samples obtained from healthy individuals and COVID-19 patients who were stratified according to the disease severity and fibrotic-like changes on chest computed tomography (CT) scans. Surfactant Protein D (SP-D), Matrix Metalloproteinase 8 (MMP8), Krebs von den lungen-6 (KL-6), Angiotensin-Converting Enzyme 2 (ACE2), and macrophage polarization-related biomarkers were determined by ELISA. Data were collected and evaluated using regression models and receiver operating characteristic (ROC) curves.

Results

The plasma levels of SP-D, MMP8 in patients with ARDS were higher than those of non-ARDS patients. Patients with pulmonary fibrosis had higher plasma levels of SP-D compared to those without fibrotic changes. Among the biomarkers indicative of macrophage polarization, compared to non-ARDS patients, a significant increase in IL-10, Inducible nitric oxide synthase (iNOS), and Arginase-1 (Arg-1) were observed in ARDS patients, while Tumor necrosis factor-α (TNF-α) was decreased. The plasma level of IL-10 was also elevated in patients with fibrotic changes on CT, and was positively correlated with ACE2 and Arg-1. ROC curve results uncovered that SP-D showed higher efficacy in predicting pulmonary fibrosis and ARDS compared to other inflammatory markers. And IL-10 had similar predictive value with traditional inflammatory indicators such as CRP and PCT.

Conclusion

SP-D and IL-10 exhibited certain predictive abilities for the development of ARDS and pulmonary fibrosis in patients with COVID-19. The determination of these cytokines upon admission is crucial for evaluating the prognosis of COVID-19 patients.

Comparative accuracy of CA-153 and KL-6 as diagnostic and prognostic biomarkers for interstitial lung disease

BACKGROUNDS

To discern the potential of KL-6 and CA-153 as diagnostic tools for interstitial lung disease (ILD), understand their relationship with GAP (Gender, Age, and Physiology) stage, and analyze their predictive capacities alongside CT features. This research aims to enhance ILD detection and management in autoimmune patients, emphasizing the diagnostic utility of these biomarkers.

METHODS

From Mar 2017 to Mar 2024, 398 patients from Taichung Veterans General Hospital's Division of Allergy, Immunology, and Rheumatology with autoimmune diseases were prospectively enrolled. ILD diagnoses were confirmed using High-Resolution Computed Tomography (HRCT) or lung biopsy and characterized by radiologists. GAP scores were calculated for IPF prognosis. 583 serum samples were collected and tested for KL-6, CA-153, CA-199, and CA-125 using specific assays. Statistical analyses compared patients, assessed variables, determined missingness, and predicted ILD, with tools like ROC analysis and logistic regressions. Analyses were performed with IBM SPSS and MedCalc.

RESULTS

ILD patients were older, predominantly male, and had more smokers compared to non-ILD. Both KL-6 and CA-153 were higher in ILD and showed a significant, but non-interchangeable correlation. Age, BMI, smoking, and biomarker levels influenced ILD odds, with KL-6 and CA-153 being the strongest predictors. HRCT imaging highlighted these markers' roles, especially in detecting specific features. Both markers also strongly associated with GAP stages. Stratified analyses emphasized KL-6's significance in predicting ILD across both AD and non-AD groups. Complete data sensitivity analysis reinforced KL-6 and CA-153 as key ILD predictors.

CONCLUSIONS

This research emphasizes CA-153 as a feasible, cost-effective alternative to KL-6 in diagnosing and monitoring ILD. Both CA-153 and KL-6 levels were notably elevated in ILD patients, displaying a strong correlation, especially at CA-153 levels of ≤100 U/ml. They both also have significant associations with CT characteristics and GAP stages. The study reinforces the potential of CA-153, particularly in settings where KL-6 testing might be inaccessible or expensive.

CSF3 aggravates acute exacerbation of pulmonary fibrosis by disrupting alveolar epithelial barrier integrity

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive respiratory disorder characterized by poor prognosis, often presenting with acute exacerbation. The primary cause of death associated with IPF is acute exacerbation of IPF (AE-IPF). However, the pathophysiology of acute exacerbation has not been clearly elucidated yet. This study aims to investigate the underlying pathophysiological molecular mechanism in a mouse AE-PF model. C57BL/6J mice were intratracheally administered bleomycin (BLM, 5 mg/kg) to induce pulmonary fibrosis. After 14 days, lipopolysaccharide (LPS, 2 mg/kg) was injected via the trachea route. Histological assessments, including H&E and Masson staining, as well as inflammatory indicators, were included to evaluate the induction of AE-PF by BLM and LPS in mice. Transcriptomic profiling of pulmonary tissues identified CSF3 as one of the top 10 upregulated DEGs in AE-PF mice. Indeed, administration of exogenous CSF3 protein exacerbated AE-PF in mice. Mechanistically, CSF3 disrupted alveolar epithelial barrier integrity and permeability by regulating specialized cell adhesion complexes such as tight junctions (TJs) and adherens junctions (AJs) via PI3K/p-Akt/Snail pathway, contributing to the aggravation of AE-PF in mice. Moreover, the discovery of elevated sera CSF3 indicated a notable increase in IPF patients during the exacerbation of the disease. Pearson correlation analysis in IPF patients revealed significant positive associations between CSF3 levels and KL-6 levels, LDH levels, CRP levels, respectively. These results provide mechanistic insights into the role of CSF3 in exacerbating of lung fibrotic disease and indicate monitoring CSF3 levels may aid in early clinical decisions for alternative therapy in the management of rapidly progressing IPF.

Unraveling the enigma: The emerging significance of pulmonary surfactant proteins in predicting, diagnosing, and managing COVID-19

BACKGROUND

Severe cases of COVID-19 often lead to the development of acute respiratory syndrome, a critical condition believed to be caused by the harmful effects of SARS-CoV-2 on type II alveolar cells. These cells play a crucial role in producing pulmonary surfactants, which are essential for proper lung function. Specifically focusing on surfactant proteins, including Surfactant protein A (SP-A), Surfactant protein B, Surfactant protein C, and Surfactant protein D (SP-D), changes in the levels of pulmonary surfactants may be a significant factor in the pathological changes seen in COVID-19 infection.

OBJECTIVE

This study aims to gain insights into surfactants, particularly their impacts and changes during COVID-19 infection, through a comprehensive review of current literature. The study focuses on the function of surfactants as prognostic markers, diagnostic factors, and essential components in the management and treatment of COVID-19.

FINDING

In general, pulmonary surfactants serve to reduce the surface tension at the gas-liquid interface, thereby significantly contributing to the regulation of respiratory mechanics. Additionally, these surfactants play a crucial role in the innate immune system within the pulmonary microenvironment. Within the spectrum of COVID-19 infections, a compelling association is observed, characterized by elevated levels of SP-D and SP-A across a range of manifestations from mild to severe pneumonia. The sudden decline in respiratory function observed in COVID-19 patients may be attributed to the decreased synthesis of surfactants by type II alveolar cells.

CONCLUSION

Collectin proteins such as SP-A and SP-D show promise as biomarkers, offering potential avenues for predicting and monitoring pulmonary alveolar injury in the context of COVID-19. This clarification enhances our understanding of the molecular complexities contributing to respiratory complications in severe COVID-19 cases, providing a foundation for targeted therapeutic approaches using surfactants and refined clinical management strategies.

Association of Serum Krebs von den Lungen-6 (KL-6) Levels and Disease Severity in Patients Hospitalized with COVID-19

Objective

We aimed to evaluate Krebs von den Lungen-6 (KL-6) as a possible biomarker in determining disease severity in patients with moderate and severe COVID-19.

Materials and Methods

This cross-sectional study included moderate or severe COVID-19 patients; critically ill patients who were followed up in the intensive care unit were not included. KL-6 level and routine laboratory test measurements were performed on the first day of admission. The patients were also categorized according to their hyperinflammatory state.

Results

The study included 92 patients, 56 (61%) women. The National Institutes of Health (NIH) score was 2 in 52.2% of the patients and 3 in 47.8%. KL-6 levels did not significantly differ in disease severity (NIH score 2 vs. 3; p=0.15). Median KL-6 values were 52.7 (29.1) in patients with <2 COVID-19 hyperinflammatory syndrome score (cHIS) and 61.7 (32.2) in patients with cHIS ≥ 2 (p= 0.077). KL-6 values tended to be higher among the patients with lower lymphocyte counts, but the difference was not statistically significant (<1000 mm³/L p=0.006 and higher cHIS scores ≥2 p=0.07). KL-6 values were also higher in the patients with diabetes mellitus compared to the remaining patients (p =0.036).

Conclusion

There was no significant association between the serum KL-6 measured at admission and the severity of COVID-19.