Level of Fatty Acid Binding Protein 5 (FABP5) Is Increased in Sputum of Allergic Asthmatics and Links to Airway Remodeling and Inflammation

Abstract

BackgroundThe inflammatory processes in the upper and lower airways in allergic rhinitis and asthma are similar. Induced sputum and nasal lavage fluid provide a non-invasive way to examine proteins involved in airway inflammation in these conditions.ObjectivesWe conducted proteomic analyses of sputum and nasal lavage fluid samples to reveal differences in protein abundances and compositions between the asthma and rhinitis patients and to investigate potential underlying mechanisms.MethodsInduced sputum and nasal lavage fluid samples were collected from 172 subjects with 1) allergic rhinitis, 2) asthma combined with allergic rhinitis, 3) nonallergic rhinitis and 4) healthy controls. Proteome changes in 21 sputum samples were analysed with two-dimensional difference gel electrophoresis (2D-DIGE), and the found differentially regulated proteins identified with mass spectrometry. Immunological validation of identified proteins in the sputum and nasal lavage fluid samples was performed with Western blot and ELISA.ResultsAltogether 31 different proteins were identified in the sputum proteome analysis, most of these were found also in the nasal lavage fluid. Fatty acid binding protein 5 (FABP5) was up-regulated in the sputum of asthmatics. Immunological validation in the whole study population confirmed the higher abundance levels of FABP5 in asthmatic subjects in both the sputum and nasal lavage fluid samples. In addition, the vascular endothelial growth factor (VEGF) level was increased in the nasal lavage fluid of asthmatics and there were positive correlations between FABP5 and VEGF levels (r=0.660, p<0.001) and concentrations of FABP5 and cysteinyl leukotriene (CysLT) (r=0.535, p<0.001) in the nasal lavage fluid.ConclusionsFABP5 may contribute to the airway remodeling and inflammation in asthma by fine-tuning the levels of CysLTs, which induce VEGF production.

Proteomic analysis of serum and sputum analytes distinguishes controlled and poorly controlled asthmatics

“…In addition to serum, we analysed sputum from nine controlled and 8 poorly controlled subjects, and normalized biomarker concentrations to total sputum protein values. Previous studies of sputum proteomics have addressed differences in profile between patients with asthma compared to those with allergic rhinitis or healthy controls, asthma compared to COPD, CF, or bronchiectasis, or neutrophilic compared to eosinophilic asthma . These studies have also explored relationships to severity, treatment response, exercise, and other parameters .…”

Nasal protein profiles in work‐related asthma caused by different exposures

“…For proteomics analysis, 2 mL of NBS supernatant was concentrated. Protein samples were prepared and two‐dimensional differential gel electrophoresis (2D‐DIGE) was performed, as previously described . For protein identification, in‐gel digestion was conducted for the chosen gel spots and the resulting peptides were extracted and dried in a vacuum centrifuge.…”

“…Protein samples were prepared and two‐dimensional differential gel electrophoresis (2D‐DIGE) was performed, as previously described . For protein identification, in‐gel digestion was conducted for the chosen gel spots and the resulting peptides were extracted and dried in a vacuum centrifuge. Each peptide mixture was analysed by an automated EASY nanoLC 1000 (Proxeon; Thermo Fisher Scientific Inc., San Jose, California, USA) coupled to an electrospray ionization quadrupole‐orbitrap mass spectrometer (Q Exactive, Thermo Fisher Scientific Inc.).…”

“…Abundances of glutathione S‐transferase 1 (GSTP1), galectin 10 (LEG10), protein S100‐A9 (S10A9) and calcyphosin (CAYP1) were compared by Western blotting in the whole study population using precast 26‐well 12% Criterion TGX gels (Bio‐Rad), as previously described . The gel lane was loaded with 10 μl of untreated NBS.…”

“…Induced sputum and nasal lavage fluid (NLF) have been applied to characterize proteomic changes in airway diseases . The identified proteins in these samples have been mostly identical, suggesting that also NBS may be useful in the research of upper airway epithelia and as a surrogate of lower airways.…”