Inhibition of sulfur mustard induced cytotoxicity and inflammation by roxithromycin in human airway epithelial cells

Abstract

Objective Inhalation of sulfur mustard (SM) causes airway inflammation and injury. There is increasing evidence of the effectiveness of macrolide antibiotics in treating chronic airway inflammatory diseases. In this study, the anti-cytotoxic and anti-inflammatory effects of roxithromycin (RXM) were tested in vitro using SM-exposed human small airway epithelial cells (SAEC) and normal human bronchial/tracheal epithelial cells (NHBE). Methods Cytotoxicity was assayed by MTS assay or calcein AM/EthD-1 staining. Cytokine expression was analyzed by ELISA at the protein level and real time RT-PCR at the mRNA level. Inducible nitric oxide synthase (iNOS) expression was examined by immunoflourescence staining. Results SM exerted cytotoxicity in a concentration-dependent manner. RXM decreased SM cytotoxicity in SEAC and NHBE. SM stimulated the production of proinflammatory cytokines (IL-1β, IL-6, IL-8 and TNF), and RXM inhibited the overproduction of these cytokines substantially. The mRNA level of these cytokines was consistent with the secretion pattern of the protein. In addition, SM caused increased expression of iNOS and this effect was also inhibited by RXM. Conclusions RXM has anti-cytotoxic and anti-inflammatory activities in human airway epithelial cells, which depend on its ability to downregulate the production of inflammatory mediators. Thus, macrolide antibiotics can exert therapeutic effects independently of their anti-bacterial activity. This work was supported by MCBDRP grant 3.F0003_05_WR_C from the Department of Defense.