TGF-β levels are significantly increased in bronchoalveolar lavage fluid and bronchial mucosal biopsies from asthmatic patients. Therefore, because airway epithelium is one of the main TGF-β targets, the aim of the present study was to investigate, in primary cultures of human bronchial epithelial cells (HBEC), the effects on cell viability of this growth factor and its mechanisms of action. HBEC were exposed for 2 h to TGF-β (10 ng/mL), in the presence or absence of a 12 h pretreatment with either budesonide (10-8 M) or specific inhibitors of mitogen-activated protein kinases (MAPK). Six hours after TGF-β removal, HBEC apoptosis was assessed by evaluation of caspase-3 activity and fluorescence-activated cell sorting analysis (FACS), using annexin V/propidium iodide double staining. TGF-β induced an almost 30% increase in HBEC apoptosis, which was completely prevented by both budesonide and MAPK inhibitors, with the p38 selective compound SB 203580 (1 μM) being more effective than SP 600125 (20 μM) and PD 98059 (40 μM). These results indicate that TGF-β is able to exert a biologically relevant, MAPK-mediated apoptotic action in HBEC. Furthermore, given the crucial role played by HBEC apoptosis in asthma pathogenesis, our findings contribute to better elucidate the cellular and molecular mechanisms underlying the anti-asthma effects of inhaled glucocorticoids, thus also unveiling new pharmacological strategies targeted at MAPK modulation.
Protective effect of MAPK inhibitors and budesonide against apoptosis induced by TGF- in primary cultures of human bronchial epithelial cells.
VATRELLA, Alessandro;
2003-01-01
Abstract
TGF-β levels are significantly increased in bronchoalveolar lavage fluid and bronchial mucosal biopsies from asthmatic patients. Therefore, because airway epithelium is one of the main TGF-β targets, the aim of the present study was to investigate, in primary cultures of human bronchial epithelial cells (HBEC), the effects on cell viability of this growth factor and its mechanisms of action. HBEC were exposed for 2 h to TGF-β (10 ng/mL), in the presence or absence of a 12 h pretreatment with either budesonide (10-8 M) or specific inhibitors of mitogen-activated protein kinases (MAPK). Six hours after TGF-β removal, HBEC apoptosis was assessed by evaluation of caspase-3 activity and fluorescence-activated cell sorting analysis (FACS), using annexin V/propidium iodide double staining. TGF-β induced an almost 30% increase in HBEC apoptosis, which was completely prevented by both budesonide and MAPK inhibitors, with the p38 selective compound SB 203580 (1 μM) being more effective than SP 600125 (20 μM) and PD 98059 (40 μM). These results indicate that TGF-β is able to exert a biologically relevant, MAPK-mediated apoptotic action in HBEC. Furthermore, given the crucial role played by HBEC apoptosis in asthma pathogenesis, our findings contribute to better elucidate the cellular and molecular mechanisms underlying the anti-asthma effects of inhaled glucocorticoids, thus also unveiling new pharmacological strategies targeted at MAPK modulation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
