Dexamethasone induces apoptosis in pulmonary arterial smooth muscle cells. Issue 1 (December 2015)

• Record Type: Journal Article
• Authors: Price, Laura; Shao, Dongmin; Meng, Chao; Perros, Frederic; Garfield, Benjamin; Zhu, Jie; Montani, David; Dorfmuller, Peter; Humbert, Marc; Adcock, Ian; Wort, Stephen
• Is Part Of: Respiratory research. Volume 16:Issue 1(2015)
• Page Start: 1
• Page End: 16
• Publication Date: 2015-12
• Subjects: Respiratory organs -- Diseases -- Periodicals; 616.2005
• DOI: 10.1186/s12931-015-0262-y
• Languages: English
• ISSNs: 1465-993X

Abstract

Abstract Background Dexamethasone suppressed inflammation and haemodynamic changes in an animal model of pulmonary arterial hypertension (PAH). A major target for dexamethasone actions is NF-κB, which is activated in pulmonary vascular cells and perivascular inflammatory cells in PAH. Reverse remodelling is an important concept in PAH disease therapy, and further to its anti-proliferative effects, we sought to explore whether dexamethasone augments pulmonary arterial smooth muscle cell (PASMC) apoptosis. Methods Analysis of apoptosis markers (caspase 3, in-situ DNA fragmentation) and NF-κB (p65 and phospho-IKK-α/β) activation was performed on lung tissue from rats with monocrotaline (MCT)-induced pulmonary hypertension (PH), before and after day 14–28 treatment with dexamethasone (5 mg/kg/day). PASMC were cultured from this rat PH model and from normal human lung following lung cancer surgery. Following stimulation with TNF-α (10 ng/ml), the effects of dexamethasone (10−8 –10−6 M) and IKK2 (NF-κB) inhibition (AS602868, 0–3 μM (0-3×10−6 M) on IL-6 and CXCL8 release and apoptosis was determined by ELISA and by Hoechst staining. NF-κB activation was measured by TransAm assay. Results Dexamethasone treatment of rats with MCT-induced PHin vivo led to PASMC apoptosis as displayed by increased caspase 3 expression and DNA fragmentation. A similar effect was seen in vitro using TNF-α-simulated human and rat PASMC following both dexamethasone and IKK2 inhibition. Increased apoptosis was associated with a reduction in NF-κB activation and in IL-6 and CXCL8 release from PASMC. Conclusions Dexamethasone exerted reverse-remodelling effects by augmenting apoptosis and reversing inflammation in PASMC possibly via inhibition of NF-κB. Future PAH therapies may involve targeting these important inflammatory pathways.