Expression and modulation of ICAM-1, TNF-α and RANTES in human alveolar macrophages from lung-transplant recipients in vitro

Alveolar macrophages (AMs) play a central role in pulmonary inflammation in response to local stimuli. As a model for investigating anti-inflammatory drugs, we studied the effects of the cyclohexadepsipeptide antibiotic, fusafungine, and that of the glucocorticoid dexamethasone on the expression of ICAM-1, TNF-alpha and RANTES, induced in vitro by rIFN-gamma in human AMs freshly isolated from bronchoalveolar lavage fluid (BAL) obtained in lung-transplanted patients. ICAM-1 antigen expression, induced on AMs after 24 h of culture, was significantly inhibited by fusafungine in a concentration-dependent manner, as measured by flow cytometry analysis using an anti-CD54 monoclonal antibody. TNF-alpha production, but not RANTES release (measured by ELISA), was significantly inhibited. mRNA studies, by means of polymerase chain reaction amplification of complementary deoxyribonucleic acids (RT-PCR), showed no significant modification of mRNA levels, suggesting that fusafungine acts mainly at a post-transcriptional level. In the same conditions, dexamethasone significantly inhibited the release both of TNF-alpha and RANTES by AMs, mainly acting at the mRNA level, but had no effect on ICAM-1 expression. Assessment of the cellular and molecular targets of anti-inflammatory drugs in this model of human AM activation should lead to more appropriate treatment of inflammatory process of the respiratory tract. By virtue of its anti-inflammatory effects on alveolar macrophages, combined with its antibacterial properties, fusafungine should prove particularly suitable for local treatment of bacterial infections of the respiratory tract.