Calgranulin B is a small
calcium-binding protein with several immunological functions mainly involved in chronic
inflammation and
cancer. It can participate in recruitment of neutrophils and leukocytes in inflamed tissue,
oxidant/
antioxidant balance, adhesion of neutrophils to
fibronectin, and regulation of apoptosis. In a previous proteomic study, we found that
calgranulin B was up-regulated in the bronchoalveolar lavage (BAL) of patients with
idiopathic pulmonary fibrosis (IPF) with respect to controls and patients with other
interstitial lung diseases. The aims of this study are to compare
calgranulin B concentrations in BAL of patients with IPF and
sarcoidosis and controls by a quantitative method, to look for correlations with clinical data, and to evaluate
calgranulin B expression in lung tissue of IPF patients by immunohistochemistry. A modification of a commercial ELISA was used to determine
calgranulin B concentrations in BAL of 16 patients with IPF (a group of patients in which we previously performed proteomic analysis), 17 patients with
sarcoidosis, and 7 controls. The immunohistochemistry was done in a subgroup of patients with IPF and a control group of lung transplant donors.
Calgranulin B concentrations were significantly higher in patients with IPF than controls (p < 0.01); they were inversely correlated with FVC and DLCO values and directly correlated with neutrophil and eosinophil percentages in BAL. Immunohistochemistry revealed a patchy distribution of
calgranulin B, predominantly around areas of fibrotic remodeling.
Calgranulin B may be a trigger molecule involved in the evolution and progression of IPF, being overexpressed in BAL of patients with IPF with severe functional deterioration and in the peribronchiolar area bordering zones of honeycombing.