Protein S is protective in pulmonary fibrosis

Essentials Epithelial cell apoptosis is critical in the pathogenesis of idiopathic pulmonary fibrosis. Protein S, a circulating anticoagulant, inhibited apoptosis of lung epithelial cells. Overexpression of protein S in lung cells reduced bleomycin-induced pulmonary fibrosis. Intranasal therapy with exogenous protein S ameliorated bleomycin-induced pulmonary fibrosis.

SUMMARY

Background Pulmonary fibrosis is the terminal stage of interstitial lung diseases, some of them being incurable and of unknown etiology. Apoptosis plays a critical role in lung fibrogenesis. Protein S is a plasma anticoagulant with potent antiapoptotic activity. The role of protein S in pulmonary fibrosis is unknown. Objectives To evaluate the clinical relevance of protein S and its protective role in pulmonary fibrosis. Methods and Results The circulating level of protein S was measured in patients with pulmonary fibrosis and controls by the use of enzyme immunoassays. Pulmonary fibrosis was induced with bleomycin in transgenic mice overexpressing human protein S and wild-type mice, and exogenous protein S or vehicle was administered to wild-type mice; fibrosis was then compared in both models. Patients with pulmonary fibrosis had reduced circulating levels of protein S as compared with controls. Inflammatory changes, the levels of profibrotic cytokines, fibrosis score, hydroxyproline content in the lungs and oxygen desaturation were significantly reduced in protein S-transgenic mice as compared with wild-type mice. Wild-type mice treated with exogenous protein S showed significant decreases in the levels of inflammatory and profibrotic markers and fibrosis in the lungs as compared with untreated control mice. After bleomycin infusion, mice overexpressing human protein S showed significantly low caspase-3 activity, enhanced expression of antiapoptotic molecules and enhanced Akt and Axl kinase phosphorylation as compared with wild-type counterparts. Protein S also inhibited apoptosis of alveolar epithelial cells in vitro. Conclusions These observations suggest clinical relevance and a protective role of protein S in pulmonary fibrosis.

Circulating fibrocytes correlate with the asthma control test score

BACKGROUND

Bronchial asthma is characterised by airway inflammation and remodelling with a decline of lung function. Fibrocytes are bone marrow-derived mesenchymal progenitor cells that play important roles in the pathogenesis of airway remodelling. Several clinical parameters are currently being used in routine clinical practice to assess outcome of therapy in asthma including frequency of rescue with short-acting β2-agonist and the asthma control test. In this study, we hypothesised that asthma control test is associated with circulating levels of fibrocytes in bronchial asthma.

METHODS

There were 20 patients with asthma and seven healthy controls. The number of CD45(+)Collagen I(+) circulating fibrocytes was assessed in the peripheral blood by flow cytometry.

RESULTS

The number of circulating fibrocytes was significantly increased in asthma patients with moderate and severe disease compared to controls, and it was inversely correlated with % forced expiratory volume in one second and % forced vital capacity (%FVC). The frequency of inhalation of short-acting β2 agonist and the asthma control test score was significantly and inversely correlated with the number of circulating fibrocytes.

CONCLUSION

The results of this study showed that the number of circulating fibrocytes is inversely correlated with clinical asthma control parameters, further supporting the relevance of measuring circulating fibrocytes as a marker of clinical control in bronchial asthma.