Effects of Budesonide on P38 MAPK Activation, Apoptosis and IL-8 Secretion, Induced by TNF-α and Haemophilus Influenzae in Human Bronchial Epithelial Cells

Abstract

Non-typeable Haemophilus influenzae (NTHi) is one of the most frequently involved pathogens in bacterial exacerbations of chronic obstructive pulmonary disease (COPD). In the airways, the main tissue target of NTHi is bronchial epithelium, where this pathogen can further amplify the inflammatory and structural changes induced by proinflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha). Therefore, the aim of this study is to investigate, in primary cultures of human bronchial epithelial cells, the effects of NTHi on signal transduction pathways, apoptotic events and chemokine production activated by TNF-alpha. Moreover, we also evaluated the effects exerted on such cellular and molecular phenomena by a corticosteroid drug. p38 mitogen-activated protein kinase (MAPK) phosphorylation was analyzed by Western blotting, using an anti-phospho-p38 MAPK monoclonal antibody. Apoptosis was assayed by active caspase-3 expression. Interleukin-8 (IL-8/CXCL8) was detected in cell-free culture supernatants by ELISA. TNF-alpha induced a significant increase in p38 MAPK phosphorylation. NTHi was able to potentiate the stimulatory actions of TNF-alpha on caspase-3 expression and, to a lesser extent, on IL-8 secretion. These effects were significantly (P less than 0.01) inhibited by a pharmacological pre-treatment with budesonide. These results suggest that TNF-alpha is able to stimulate, via activation of p38 MAPK signalling pathway, IL-8 release and airway epithelial cell apoptosis; the latter effect can be markedly potentiated by NTHi. Furthermore, budesonide can be very effective in preventing, through inhibition of p38 MAPK phosphorylation, both structural and proinflammatory changes elicited in bronchial epithelium by TNF-alpha and NTHi.

Apoptosis and the Airway Epithelium

“…The TNF pathway was activated, but a direct link to TNF- α in the sputum sol phase was not demonstrated. Another recent study demonstrated that TNF- α stimulated caspase-3 activation and IL-8 expression in primary airway epithelial cells via phosphorylation of p38 mitogen-activated protein kinase (MAPK), an effected potentiated by concurrent exposure to nontypeable Haemophilus influenzae [66]. Activation of NF- κ B pathways and involvement of TRADD were not examined in this study.…”

Liu-He-Tang inhibited plaque formation by human respiratory syncytial virus infection in cell lines of the human respiratory tract

“…LHT could stimulate IFN-␤ and TNF-␣ before viral infection to prevent HRSV infection. However, TNF-␣ can also induce apoptosis of bronchial epithelium to cause pathology (Gallelli et al, 2010). Our results showed LHT would not stimulate TNF-␣ secretion after HRSV inoculation.…”

Sheng-Ma-Ge-Gen-Tang (Shoma-kakkon-to) inhibited cytopathic effect of human respiratory syncytial virus in cell lines of human respiratory tract

“…Although it is a potent antiviral cytokine, TNF-␣ is also potent to activate p38MAPK to induce apoptosis of bronchial epithelia (Gallelli et al, 2010). Therefore, respiratory mucosa can defense HRSV infection with the expense of epithelial apoptosis.…”