Proteomic analysis of bronchoalveolar lavage fluid samples obtained from West Highland White Terriers with idiopathic pulmonary fibrosis, dogs with chronic bronchitis, and healthy dogs.

OBJECTIVE: To evaluate protein expression in bronchoalveolar lavage fluid (BALF) obtained from West Highland White Terriers with idiopathic pulmonary fibrosis (IPF), dogs with chronic bronchitis, and healthy control dogs to identify potential biomarkers for IPF. SAMPLES: BALF samples obtained from 6 West Highland White Terriers with histologically confirmed IPF, 5 dogs with chronic bronchitis, and 4 healthy Beagles. PROCEDURES: Equal amounts of proteins in concentrated BALF samples were separated via 2-D differential gel electrophoresis. Proteins that were differentially expressed relative to results for healthy control dogs were identified with mass spectrometry and further verified via western blotting. RESULTS: Expression of 6 proteins was upregulated and that of 1 protein was downregulated in dogs with IPF or chronic bronchitis, compared with results for healthy dogs. Expression of proteins ß-actin, complement C3, α-1-antitrypsin, apolipoprotein A-1, haptoglobin, and transketolase was upregulated, whereas expression of lysozyme C was downregulated. CONCLUSIONS AND CLINICAL RELEVANCE: Proteomics can be used to search for biomarkers and to reveal disease-specific mechanisms. The quantitative comparison of proteomes for BALF obtained from dogs with IPF and chronic bronchitis and healthy dogs revealed similar changes for the dogs with IPF and chronic bronchitis, which suggested a common response to disease processes in otherwise different lung diseases. Specific biomarkers for IPF were not identified.

Procollagen type III amino terminal propeptide concentrations in dogs with idiopathic pulmonary fibrosis compared with chronic bronchitis and eosinophilic bronchopneumopathy.

Idiopathic pulmonary fibrosis (IPF) is characterised by an abnormal accumulation of collagen type III in the pulmonary interstitium. Procollagen type III amino terminal propeptide (PIIINP) is used as a marker of collagen type III synthesis. In this study, the concentrations of PIIINP were investigated in dogs with IPF (n=15), dogs with chronic bronchitis (CB, n=19), dogs with eosinophilic bronchopneumopathy (EBP, n=13) and healthy dogs (n=25). PIIINP concentrations in serum and bronchoalveolar lavage fluid (BALF) were analysed by radioimmunoassay. Serum PIIINP values did not differ between groups, indicating that serum PIIINP is not useful in evaluating respiratory diseases in dogs. BALF PIIINP was significantly elevated in dogs with IPF compared with healthy dogs (P=0.002) and dogs with CB (P<0.001). BALF PIIINP was significantly higher in dogs with EBP than in dogs with CB (P=0.003) or healthy dogs (P=0.022). There were no differences in BALF PIIINP concentrations between dogs with IPF and dogs with EBP or between dogs with CB and healthy dogs. These results indicate that IPF is associated with elevated BALF PIIINP concentrations. BALF PIIINP concentrations also are elevated in EBP, possibly due to secondary fibrotic changes.