View Abstract

A5751 - Comparison of the Antifibrotic Efficacy of the Pan-Histone Deacetylase-Inhibitor Panobinostat Versus the IPF-Drug Pirfenidone in Fibroblasts from Patients with Idiopathic Pulmonary Fibrosis
Author Block: M. Korfei1, D. Stelmaszek1, S. Skwarna1, S. Chillappagari1, A. C. Bach1, B. MacKenzie1, C. Ruppert1, S. Saito2, P. Mahavadi1, W. Klepetko3, L. Fink4, W. Seeger5, J. A. Lasky2, S. S. Pullamsetti6, O. Krämer7, A. Guenther1; 1Department of Internal Medicine and Biomedical Research Center Seltersberg (BFS), German Center for Lung Research (DZL), Justus-Liebig-University Giessen, Giessen, Germany, 2Department of Medicine, Section of Pulmonary Diseases, Tulane University Health Science Center, New Orleans, LA, United States, 3Department of Thoracic Surgery, Vienna General Hospital, Vienna, Austria, 4Institute of Pathology and Cytology in Wetzlar, German Center for Lung Research (DZL), Justus-Liebig-University Giessen, Giessen, Germany, 5Department of Internal Medicine and Excellence Cluster Cardio-Pulmonary System (ECCPS), German Center for Lung Research (DZL), Justus-Liebig-University Giessen, Giessen, Germany, 6Max-Planck-Institute for Heart and Lung Research in Bad Nauheim, German Center for Lung Research (DZL), Justus-Liebig-University Giessen, Giessen, Germany, 7Department of Toxicology, University Medical Center, Mainz, Germany.
Rationale: Idiopathic pulmonary fibrosis (IPF) is an incurable lung disease with a poor prognosis. Pirfenidone is the first antifibrotic agent to be approved for IPF-treatment as it is able to slow down disease progression. Because epigenetic alterations are associated with IPF, histone deacetylase (HDAC)-inhibitors have recently been proven to attenuate fibrotic remodeling in vitro and in vivo. This study compared the effects of pirfenidone with the pan-HDAC-inhibitor panobinostat/LBH589, a FDA-approved drug for the treatment of multiple myeloma, head-to-head on survival, fibrotic activity and proliferation of primary IPF-fibroblasts in vitro. Methods: Primary fibroblasts from five IPF-patients were incubated for 24h with vehicle (0.25% DMSO), panobinostat (85nmol) or pirfenidone (2.7 mM), followed by assessment of proliferation and expression analyses for profibrotic and anti-apoptosis genes, as well as for ER-stress and apoptosis-markers. In addition, the expression status of class-I and class-II HDAC enzymes was examined. Results: Treatment of IPF-fibroblasts with pirfenidone or panobinostat resulted in significantly downregulated expression of various extracellular matrix (ECM)-associated genes (COL1A1, COL3A1, ACTA2, FN), in comparison to vehicle-treated cells. In addition, both drugs decreased protein level of phosphorylated (p)-STAT3, a transcription factor mediating profibrotic responses, in treated IPF-fibroblasts. Interestingly, the profibrotic genes CNN1, DES and P4HTM were exclusively downregulated by pirfenidone-, but not by panobinostat-treatment. Of note, an increase in histone acetylation (H3K27ac) was observed in response to both treatments, but was much more pronounced and excessive in panobinostat-treated IPF-fibroblasts. In contrast to some published studies, pirfenidone did not decrease the proliferation of IPF-fibroblasts, but which was significantly suppressed by panobinostat-treatment, as indicated by WST1-assay and markedly diminished level of cyclin-D1 and p-histone H3. Further, panobinostat-treatment decreased markedly the expression of survival-related genes Bcl-XL and BIRC5/survivin, and was associated with induction of ER-stress and apoptosis in IPF-fibroblasts. Importantly, pirfenidone-therapy led also to significant downregulation of the cancer-associated gene BIRC5, but was not associated with induction of pro-apoptotic ER-stress. Pirfenidone led also to increased expression of class-II HDAC5 and -6, and decreased tubulin-acetylation. But, in line with slightly increased chromatin-acetylation, pirfenidone reduced the expression of class-I HDAC1 and -2. Conclusions: We conclude that, beside other antifibrotic mechanisms, pirfenidone reduces profibrotic signaling also through weak epigenetic alterations in IPF-fibroblasts, thereby permitting survival of (altered) fibroblasts. In contrast, the anti-cancer drug panobinostat reduces profibrotic expression while inducing cell death in IPF-fibroblasts. We believe that HDAC-inhibitors such as panobinostat can present a novel therapeutic strategy (in addition to pirfenidone) for IPF.