Inhibition of Cell Apoptosis and Amelioration of Pulmonary Fibrosis by Thrombomodulin

Abstract

Pulmonary fibrosis is the terminal stage of a group of idiopathic interstitial pneumonias, of which idiopathic pulmonary fibrosis is the most frequent and fatal form. Recent studies have shown that recombinant human thrombomodulin (rhTM) improves exacerbation and clinical outcome of idiopathic pulmonary fibrosis, but the mechanism remains unknown. This study evaluated the mechanistic pathways of the inhibitory activity of rhTM in pulmonary fibrosis. Transgenic mice overexpressing human transforming growth factor-β1 that develop spontaneously pulmonary fibrosis, and wild-type mice treated with bleomycin were used as models of lung fibrosis. rhTM was administered to mice by i.p. injection or by the intranasal route. Therapy with rhTM significantly decreased the concentration of high mobility group box1, interferon-γ, and fibrinolytic markers, the expression of growth factors including transforming growth factor-β1, and the degree of lung fibrosis. rhTM significantly suppressed apoptosis of lung epithelial cells in in vivo and in vitro experiments. The results of the present study demonstrated that rhTM can inhibit bleomycin-induced pulmonary fibrosis and transforming growth factor-β1-driven exacerbation and progression of pulmonary fibrosis, and that apart from its well-recognized anticoagulant and anti-inflammatory properties, rhTM can also suppress apoptosis of lung epithelial cells.

A Staphylococcus pro-apoptotic peptide induces acute exacerbation of pulmonary fibrosis

“…We performed radiological evaluation of the chest using a micro-CT (Latheta LCT-200, Hitachi Aloka Medical, Tokyo, Japan). Mice received isoflurane inhalation as anesthesia and were placed in a prone position for data acquisition 67 . Six specialists in respiratory diseases blinded to the treatment groups scored the chest CT findings based on the following criteria: score 1, normal lung findings; 2, intermediate findings; 3, slight lung fibrosis; 4, intermediate findings; 5, moderate lung fibrosis; 6, intermediate findings; and 7, advanced lung fibrosis ( Supplementary Fig.…”

“…Six specialists in respiratory diseases blinded to the treatment groups scored the chest CT findings based on the following criteria: score 1, normal lung findings; 2, intermediate findings; 3, slight lung fibrosis; 4, intermediate findings; 5, moderate lung fibrosis; 6, intermediate findings; and 7, advanced lung fibrosis ( Supplementary Fig. 1a) 67 . We used the Ashcroft lung fibrosis score and the hydroxyproline content of the lungs to validate the CT findings ( Supplementary Fig.…”

“…We then sacrificed mice by anesthesia overdose, and resected the lungs to fix in formalin, embed in paraffin and prepare for hematoxylin and eosin staining. The severity of lung fibrosis was quantitated based on the Ashcroft criteria 67 . The level of TGFβ1 was measured using commercial enzyme immunoassay kit from BD Biosciences Pharmingen (San Diego, CA).…”

“…Equal amounts of cellular lysate protein were mixed with Laemmli sample buffer and separated by SDS-PAGE. Western blotting was then performed after electrophoretic transfer of proteins from sodium dodecyl sulfate-polyacrylamide gels to nitrocellulose membranes and using anti-phospho-Akt, anti-Akt, anti-cleaved caspase-3 or anti-β-actin antibody (Cell Signaling, Danvers, MA) 67 . The intensity of the bands was quantified by densitometry using the public domain NIH imageJ program (wayne@codon.nih.gov; Wayne Rasband, NIH, Research Service Branch).…”

Therapeutic Potential of Thrombomodulin in Renal Fibrosis of Nephrotoxic Serum Nephritis in Wistar-Kyoto Rats

“…Recombinant human soluble TM (rhTM) was approved in 2008 and has been used for treatment of disseminated intravascular coagulation in Japan. Recently, the antifibrotic efficacy of rhTM has been reported [3,4]. Several studies have shown its therapeutic effects on acute exacerbation of idiopathic pulmonary fibrosis, which is pathophysiologically characterized by extravascular and intra-alveolar thrombin activation and fibrin deposition following epithelial and endothelial injury [5,6].…”