PAR-2, IL-4R, TGF-β and TNF-α in bronchoalveolar lavage distinguishes extrinsic allergic alveolitis from sarcoidosis

Diagnosis of Fibrotic Hypersensitivity Pneumonitis: Is There a Role for Biomarkers?

Hypersensitivity pneumonitis is a complex interstitial lung syndrome and is associated with significant morbimortality, particularly for fibrotic disease. This condition is characterized by sensitization to a specific antigen, whose early identification is associated with improved outcomes. Biomarkers measure objectively biologic processes and may support clinical decisions. These tools evolved to play a crucial role in the diagnosis and management of a wide range of human diseases. This is not the case, however, with hypersensitivity pneumonitis, where there is still great room for research in the path to find consensual diagnostic biomarkers. Gaps in the current evidence include lack of validation, validation against healthy controls alone, small sampling and heterogeneity in diagnostic and classification criteria. Furthermore, discriminatory accuracy is currently limited by overlapping mechanisms of inflammation, damage and fibrogenesis between ILDs. Still, biomarkers such as BAL lymphocyte counts and specific serum IgGs made their way into clinical guidelines, while others including KL-6, SP-D, YKL-40 and apolipoproteins have shown promising results in leading centers and have potential to translate into daily practice. As research proceeds, it is expected that the emergence of novel categories of biomarkers will offer new and thriving tools that could complement those currently available.

Interstitial Score and Concentrations of IL-4Rα, PAR-2, and MMP-7 in Bronchoalveolar Lavage Fluid Could Be Useful Markers for Distinguishing Idiopathic Interstitial Pneumonias

Idiopathic interstitial pneumonia (IIP) entails a variable group of lung diseases of unknown etiology. Idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, interstitial lung diseases related to connective tissue disease (CTD-ILD), and hypersensitivity pneumonitis (HP) can manifest with similar clinical, radiological, and histopathological features. In a differential diagnosis, biomarkers can play a significant role. We assume that levels of specific cyto- or chemokines or their receptors can signal pathogenetic processes in the lungs. Eighty patients with different types of idiopathic interstitial pneumonia were enrolled in this study. Cell counts and concentrations of tumor necrosis factor (TNF)-α, interleukin-4 receptor α, proteinase-activated receptor (PAR)-2, matrix metalloproteinase (MMP)-7, and B cell-activating factor were measured in bronchoalveolar lavage fluid using commercial ELISA kits. High resolution computer tomography results were evaluated using alveolar and interstitial (IS) score scales. Levels of TNF-α were significantly higher in HP compared to fibrosing IIP (p < 0.0001) and CTD-ILD (p = 0.0381). Concentrations of IL-4Rα, PAR-2, and MMP-7 were positively correlated with IS (p = 0.0009; p = 0.0256; p = 0.0015, respectively). Since TNF-α plays a major role in inflammation, our results suggest that HP is predominantly an inflammatory disease. From the positive correlation with IS we believe that IL-4Rα, PAR-2, and MMP-7 could serve as fibroproliferative biomarkers in differential diagnosis of IIP.

Bronchoalveolar lavage cell profiles and proteins concentrations can be used to phenotype extrinsic allergic alveolitis patients

Background

Extrinsic allergic alveolitis (EAA) patients form heterogenous group with different clinical manifestation and different prognosis. We aimed to determine how to phenotype distinct EAA subgroups. Predictive role of the bronchoalveolar lavage fluid (BALF) IL-4Rα concentration at the time of diagnosis with regard to the clinical behavior in EAA patients was studied.

Methods

Concentrations of MMP-7, IL-4Rα, TNF-α, and PAR-2 were measured in the BALF od 71 EAA patients at the time of diagnosis. Lung functions and outcome data were assessed at 12 months after the diagnosis. Correlations between the BALF protein concentration, cell profile, lung functions and patient outcome were determined.

Results

We found positive correlations between BALF IL-4Rα concentration and BALF eosinophils (p = 0,006), negative correlation between IL-4Rα BALF concentration and diffusing capacity (DLco) (p = 0,003), negative correlation between IL-4Rα BALF concentration and forced vital capacity (FVC) (p = 0,004) and negative correlation between IL-4Rα concentration and BALF lymphocytes (p = 0,04). The BALF concentration of IL-4Rα was significantly higher in acute exacerbation patients (p = 0,0032) and in patients progressing despite corticosteroid treatment (p = 0,04). We observed a positive correlation between MMP-7 BALF concentration and the BALF lymphocytes (p = 0.05), negative correlation between the PAR-2 BALF concentration and DLco (p = 0.04) and a negative correlation between the BALF TNF-α concentration and DLco (p = 0.03).

Conclusions

Specific subgroup of EAA patients with more severe functional impact, distinct BALF cell profile and higher IL-4Rα BALF concentration can be differentiated. Correlations between the BALF concentrations of PAR-2, MMP-7 and TNF-α with clinical parameters may reflect the role of inflammation in the pathogenesis of EAA.

Quercetin alleviates cell apoptosis and inflammation via the ER stress pathway in vascular endothelial cells cultured in high concentrations of glucosamine

Glucosamine is a possible cause of vascular endothelial injury in the initial stages of atherosclerosis, through endoplasmic reticulum (ER) stress resulting in fatty streaks in the vascular wall. Quercetin is an anti‑diabetic and cardiovascular protective agent that has previously been demonstrated to reduce ER stress in human umbilical vein endothelial cells (HUVECs). The present study aimed to investigate whether quercetin prevents glucosamine‑induced apoptosis and inflammation via ER stress pathway in HUVECs. The effect of quercetin on cell viability, apoptosis, and protein expression levels of inflammatory cytokines and ER stress markers was investigated in glucosamine‑supplemented HUVECs. Quercetin was demonstrated to protect against glucosamine‑induced apoptosis, improved cell viability, and inhibited expression of pro‑inflammatory factors and endothelin‑1. Quercetin treatment also reduced the expression levels of glucose‑regulated protein 78, phosphorylated protein kinase‑like ER kinase, phosphorylated c‑Jun N‑terminal kinase and C/EBP homologous protein. In conclusion, quercetin may have auxiliary therapeutic potential against glucosamine‑induced cell apoptosis and inflammation, which may be partially due to alleviation of ER stress.

Metabolic hormones, apolipoproteins, adipokines, and cytokines in the alveolar lining fluid of healthy adults: compartmentalization and physiological correlates

Objectives

Our current understanding of hormone regulation in lung parenchyma is quite limited. We aimed to quantify a diverse array of biologically relevant protein mediators in alveolar lining fluid (ALF), compared to serum concentrations, and explore factors associated with protein compartmentalization on either side of the air-blood barrier.

Research Design and Methods

Participants were 24 healthy adult non-smoker volunteers without respiratory symptoms or significant medical conditions, with normal lung exams and office spirometry. Cell-free bronchoalveolar lavage fluid and serum were analyzed for 24 proteins (including enteric and metabolic hormones, apolipoproteins, adipokines, and cytokines) using a highly sensitive multiplex ELISA. Measurements were normalized to ALF concentrations. The ALF:serum concentration ratios were examined in relation to measures of protein size, hydrophobicity, charge, and to participant clinical and spirometric values.

Results

ALF measurements from 24 individuals detected 19 proteins, including adiponectin, adipsin, apoA-I, apoA-II, apoB, apoC-II, apoC-III, apoE, C-reactive protein, ghrelin, glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, resistin, and visfatin. C-peptide and serpin E1 were not detected in ALF for any individual, and IL-6, IL-10, and TNF-alpha were not detected in either ALF or serum for any individual. In general, ALF levels were similar or lower in concentration for most proteins compared to serum. However, ghrelin, resistin, insulin, visfatin and GLP-1 had ALF concentrations significantly higher compared to serum. Importantly, elevated ALF:serum ratios of ghrelin, visfatin and resistin correlated with protein net charge and isoelectric point, but not with molecular weight or hydrophobicity.

Conclusions

Biologically relevant enteric and metabolic hormones, apolipoproteins, adipokines, and cytokines can be detected in the ALF of healthy individuals. For the proteins measured, charge may influence trafficking and compartmentalization to the alveolar airspace more than molecular weight or hydrophobicity. These data may have implications for homeostasis and drug delivery to the lung.